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KaiC Additionally, overexpression of has been shown to strongly repress the "kaiBC" promoter, while "kaiA" overexpression has experimentally enhanced the "kaiBC" promoter. These positive and negative binding elements mirror a feedback mechanism of rhythm generation conserved across many different species. phosphorylation oscillates with a period of approximately 24 hours when placed in vitro with the three recombinant Kai proteins, incubated with ATP. The circadian rhythm of phosphorylation persists in constant darkness, regardless of "Synechococcus" transcription rates. This oscillation rate is thought to be controlled by the ratio of phosphorylated to unphosphorylated protein. phosphorylation ratio is a main factor in the activation of "kaiBC" promoter as well. The "kaiBC" operon is transcribed in a circadian fashion and precedes build up by about 6 hours, a lag thought to play a role in feedback loops. "kaiA", "kaiB", and "kaiC" have been shown to be essential genetic components in "Synechococcus elongatus" for circadian rhythms. Experiments have also shown that enhances the KaiA-KaiB interaction in yeast cells and in vitro. This implies that there may be the formation of a heteromultimeric complex composed of the three Kai proteins with serving as a bridge between KaiA and KaiB. Alternatively, may form a heterodimer with KaiA or KaiB to induce a conformational change | https://en.wikipedia.org/wiki?curid=39103747 |
KaiC Variations in the C-terminal region of each of their proteins suggest functional divergence between the Kai clock proteins, however there are critical interdependencies between the three paralogs. Cyanobacteria are the simplest organisms with a known mechanism for the generation of circadian rhythms. ATPase activity is temperature compensated from 25 to 50 degrees Celsius and has a Q10 of about 1.1 (Q10 values around 1 indicate temperature compensation). Because the period of phosphorylation is temperature compensated and agrees with "in vivo" circadian rhythms, is thought to be the mechanism for basic circadian timing in "Synechococcus". "∆kaiABC" individuals, one of the more common mutants, grow just as well as wild type individuals but they lack rhythmicity. This is evidence that the "kaiABC" gene cluster is not necessary for growth. In addition to the PTO regulating the autokinase and autophosphatase activities of KaiC, there is also evidence for a TTFL, similar to other eukaryotes, that governs the circadian rhythm in outputs of the clock. By studying the structure and the activities of KaiC, several roles of in the TTFL were suggested. The similar structures of to the RecA/DnaB superfamily suggested a possible role for in direct DNA binding and promoting of transcription. knock-out(KO) experiments determined to be a negative regulator of the "kaiBC" promoter sequence but it was found working through a separate, SasA/RpaA pathway, as was found to be not a transcription factor | https://en.wikipedia.org/wiki?curid=39103747 |
KaiC However, elimination of the PTO did not fully eliminate the rhythmicity in "kaiBC" promoter activities, suggesting that the PTO is not necessary in generating rhythms in the TTFL. In truth, the activities of outside of the PTO is still relatively unknown. Recent experiments have found that the oscillations in the cell cycle and circadian rhythms of "Synechococcus" are linked together through a one way mechanism. The circadian clock gates cells division, only allowing it to proceed at certain phases. The cell cycle does not appear to have any effect on the circadian clock though. When binary fission occurs, the daughter cells inherit the mother cell's circadian clock and are in phase with the mother cell. The circadian gating of cell division may be a protective feature to prevent division at a vulnerable phase. Phases in which has high ATPase activity do not allow for cell division to take place. In mutants with constantly elevated ATPase activity, the protein CikA is absent. CikA is a major factor in the input pathway and causes dependent cell elongation. The recreation of a circadian oscillator "in vitro" in the presence of only KaiA, KaiB, KaiC, and ATP has sparked interest in the relationship between cellular biochemical oscillators and their associated transcription-translation feedback loops (TTFLs) | https://en.wikipedia.org/wiki?curid=39103747 |
KaiC TTFLs have long been assumed to be the core of circadian rhythmicity, but that claim is now being tested again due to the possibility that the biochemical oscillators could constitute the central mechanism of the clock system, regulating and operating within TTFLs that control output and restore proteins essential to the oscillators in organisms, such as the KaiABC system in "Synechococcus". Two models have been proposed to describe the relationship between the biochemical and TTFL regulation of circadian rhythms: a master/slave oscillator system with the TTFL oscillator synchronizing to the biochemical oscillator and an equally weighted coupled oscillator system in which both oscillators synchronize and influence the other oscillator. Both are coupled oscillator models that account for the high stability of the timing mechanism within "Synechococcus". The biochemical oscillator relies on redundant molecular interactions based on the law of mass action, whereas the TTFL relies on cellular machinery that mediates translation, transcription, and degradation of mRNA and proteins. The different types of interactions driving the two oscillators allows the circadian clock to be resilient to changes within the cell, such as metabolic fluctuation, temperature changes, and cell division. Though the period of the circadian clock is temperature compensated, the phosphorylation of can be stably entrained to a temperature cycle | https://en.wikipedia.org/wiki?curid=39103747 |
KaiC The phosphorylation of was successfully entrained "in vitro" to temperature cycles with periods between 20 and 28 hours using temperature steps from 30 °C to 45 °C and vice versa. The results reflect a phase-dependent shift in the phase of the phosphorylation rhythms. The period of the circadian clock was not changed, reinforcing the temperature compensation of the clock mechanism. A 2012 study out of Vanderbilt University shows evidence that acts as a phospho-transferase that hands back phosphates to ADP on the T432 (threonine residue at position 432) and S431 (serine residue 431) indicating that effectively serves as an ATP synthase. Various mutants have been identified and their phenotypes studied. Many mutants show a change in the period of their circadian rhythms. | https://en.wikipedia.org/wiki?curid=39103747 |
Critical plane analysis refers to the analysis of stresses or strains as they are experienced by a particular plane in a material, as well as the identification of which plane is likely to experience the most extreme damage. is widely used in engineering to account for the effects of cyclic, multiaxial load histories on the fatigue life of materials and structures. When a structure is under cyclic multiaxial loading, it is necessary to use multiaxial fatigue criteria that account for the multiaxial loading. If the cyclic multiaxial loading is nonproportional it is mandatory to use a proper multiaxial fatigue criteria. The multiaxial criteria based on the Critical Plane Method are the most effective criteria. For the plane stress case, the orientation of the plane may be specified by an angle in the plane, and the stresses and strains acting on this plane may be computed via Mohr's circle. For the general 3D case, the orientation may be specified via a unit normal vector of the plane, and the associated stresses strains may be computed via a tensor coordinate transformation law. The chief advantage of critical plane analysis over earlier approaches like Sines rule, or like correlation against maximum principal stress or strain energy density, is the ability to account for damage on specific material planes. This means that cases involving multiple out-of-phase load inputs, or crack closure can be treated with high accuracy. Additionally, critical plane analysis offers the flexibility to adapt to a wide range of materials | https://en.wikipedia.org/wiki?curid=39112255 |
Critical plane analysis Critical plane models for both metals and polymers are widely used. Modern procedures for critical plane analysis trace back to research published in 1973 in which M. W. Brown and K. J. Miller observed that fatigue life under multiaxial conditions is governed by the experience of the plane receiving the most damage, and that both tension and shear loads on the critical plane must be considered. | https://en.wikipedia.org/wiki?curid=39112255 |
Adaptive fluid-infused porous film Adaptive fluid-infused porous films change states when stretched, allowing for dynamic control over transparency and wettability. They were developed by researchers at Harvard University. The same team previously invented Slippery Liquid Infused Porous Surfaces (SLIPS) which served as the base technology to control wettability in Adaptive fluid-infused porous film. The material is a thin elastic film that contains nano-sized pores. When in a normal relaxed state, if droplets of liquid are applied to the film, they will roll freely along the smooth surface. However, when the film is stretched, any droplets of liquid that are applied to the film will be held in place on the film. If the tension on the film is later released, the film will return to its normal relaxed state, and the droplet will again move along the smooth surface. The film also becomes more transparent when stretched, allowing the material to be dynamically controlled with regards to both the wettability and transparency of the material. | https://en.wikipedia.org/wiki?curid=39116569 |
Partial dislocation Partial dislocations are a decomposed form of dislocations that occur within a material. An extended dislocation is a dislocation that has dissociated into partial dislocations. The vector sum of the Burgers vectors of the partial dislocations is the Burgers vector of the extended dislocation. A dislocation will decompose into partial dislocations if the energy state of the sum of the partials is less than the energy state of the original dislocation. This is summarized by "Frank's Energy Criterion": "Shockley partial dislocations" generally refer to a pair of dislocations which can lead to the presence of stacking faults. This pair of partial dislocations can enable dislocation motion by allowing an alternate path for atomic motion. In FCC systems, an example of Shockley decomposition is: Which is energetically favorable: The components of the "Shockley Partials" must add up to the original vector that is being decomposed: "Frank partial dislocations" are sessile, or immobile, but can move by diffusion of atoms. In FCC systems, Frank partials are given by: Shockley partials and Frank partials can combine to form a "Thompson tetrahedron", or a "stacking fault tetrahedron". The Lomer–Cottrell lock is formed by partial dislocations and is sessile. | https://en.wikipedia.org/wiki?curid=39133628 |
Radiation effects on optical fibers When optical fibers are exposed to ionizing radiation such as energetic electrons, protons, neutrons, X-rays, Ƴ-radiation, etc., they undergo 'damage'. The term 'damage' primarily refers to the additional loss of the propagating optical signal leading to decreased power at the output end which could lead to premature failure of the component and or system. In the professional literature, the effect is often named Radiation Induced Attenuation (RIA). The loss of power or 'darkening' occurs because the chemical bonds forming the optical fiber core are disrupted by the impinging high energy resulting in the appearance of new electronic transition states giving rise to additional absorption in the wavelength regions of interest. Once radiation source is removed, the fiber returns to its original state to some extent (a process called recovery). The extent of damage is governed by the balance between defect generation (excess attenuation) on one hand and defect annihilation (recovery) on the other hand. If the dose rate is low, an equilibrium state (between attenuation and recovery) is reached with some degree of darkening. On the contrary if the dose rate is high, the utility of fiber depends on the overall induced attenuation and the recovery time. Understanding these radiation induced effects is important particularly for space based applications where optical fibers are being considered for use in increasing number of applications | https://en.wikipedia.org/wiki?curid=39138679 |
Radiation effects on optical fibers Intrinsic defects are present in the matrix of a single component glass material like pure silica. These include per-oxy linkages, POL (≡Si-O-O-Si≡) which are oxygen interstitials, and oxygen deficient centers, ODC (≡Si-Si≡) which are oxygen vacancies. When exposed to ionizing radiation, these sites trap holes to form per-oxy radicals, POR (≡Si-O-O.) and E’ centers (≡Si.), respectively. In addition, rapidly cooled silica has strained ≡Si-O-Si≡ bonds, which are cleaved upon radiation to form non-bridging oxygen hole centers (NBOHC) depicted as ≡Si-O. and E’ centers by trapping holes and electrons, respectively. When the glass contains a second network former with the same valence as silicon such as germanium, the difference in the electronegativities favors the dopant as a hole trap. Hence greater radiation damage occurs in doped silica glass. To improve radiation resistance of pure silica core fibers, it is necessary to minimize the number density of these intrinsic defects. Minimization of defects is achieved not only by reducing the incorporation of impurities in glass but also by controlling the input gas composition, optimizing the thermal history of glass at all stages of fiber manufacturing and optimizing the stress in the fiber core. Other strategies include incorporation of dopants (such as fluorine) in the core that minimize formation of defect centers discussed above | https://en.wikipedia.org/wiki?curid=39138679 |
Radiation effects on optical fibers All optical fibers undergo some darkening depending on a number of factors that include: ionization type, optical fiber core glass composition, operating wavelength, dose rate, total accumulated dose, temperature and power propagating through the core. Since attenuation is composition dependent, it is observed that fibers having pure silica cores and fluorine down doped claddings are amongst the most radiation hard fibers. The presence of dopants in the core such as germanium, phosphorus, boron, aluminum, erbium, ytterbium, thulium, holmium etc. compromises the radiation hardness of optical fibers. To minimize damage consequences, it is better to use a pure silica core fiber at higher operating wavelength, lower dose rate, lower total accumulated dose, higher temperature (accelerated recovery) and higher signal power (photo-bleaching). In addition to these intrinsic steps, external engineering may be required to shield the fiber from the effects of radiation. Germanium-doped core fibers can be radiation hard even at high concentrations of germanium. Such fibers reach saturation, anneal well at higher temperatures and are also responsive to photo-bleaching. In case of phosphorus-doped core fibers, attenuation increases linearly with increasing phosphorus content and these fibers do not reach saturation. Recovery is very difficult even at higher temperatures. Boron, aluminum and all the rare-earth dopants significantly affect fiber loss | https://en.wikipedia.org/wiki?curid=39138679 |
Radiation effects on optical fibers Radiation performances of various SM, MM and PM fibers manufactured by different vendors that were tested in wide range of radiation environments have been compiled. | https://en.wikipedia.org/wiki?curid=39138679 |
Thermodynamic operation A thermodynamic operation is an externally imposed manipulation that affects a thermodynamic system. The change can be either in the connection or wall between a thermodynamic system and its surroundings, or in the value of some variable in the surroundings that is in contact with a wall of the system that allows transfer of the extensive quantity belonging that variable. It is assumed in thermodynamics that the operation is conducted in ignorance of any pertinent microscopic information. A thermodynamic operation requires a contribution from an independent external agency, that does not come from the passive properties of the systems. Perhaps the first expression of the distinction between a thermodynamic operation and a thermodynamic process is in Kelvin's statement of the second law of thermodynamics: "It is impossible, by means of inanimate material agency, to derive mechanical effect from any portion of matter by cooling it below the temperature of the surrounding objects." A sequence of events that occurred other than "by means of inanimate material agency" would entail an action by an animate agency, or at least an independent external agency. Such an agency could impose some thermodynamic operations. For example, those operations might create a heat pump, which of course would comply with the second law. A Maxwell's demon conducts an extremely idealized and naturally unrealizable kind of thermodynamic operation. An ordinary language expression for a thermodynamic operation is used by Edward A | https://en.wikipedia.org/wiki?curid=39144241 |
Thermodynamic operation Guggenheim: "tampering" with the bodies. A typical thermodynamic operation is externally imposed change of position of a piston, so as to alter the volume of the system of interest. Another thermodynamic operation is a removal of an initially separating wall, a manipulation that unites two systems into one undivided system. A typical thermodynamic process consists of a redistribution that spreads a conserved quantity between a system and its surroundings across a previously impermeable but newly semi-permeable wall between them. More generally, a process can be considered as a transfer of some quantity that is defined by a change of an extensive state variable of the system, corresponding to a conserved quantity, so that a transfer balance equation can be written. According to Uffink, "... thermodynamic processes only take place after an external intervention on the system (such as: removing a partition, establishing thermal contact with a heat bath, pushing a piston, etc.). They do not correspond to the autonomous behaviour of a free system." For example, for a closed system of interest, a change of internal energy (an extensive state variable of the system) can be occasioned by transfer of energy as heat. In thermodynamics, heat is not an extensive state variable of the system. The quantity of heat transferred, is however, defined by the amount of adiabatic work that would produce the same change of the internal energy as the heat transfer; energy transferred as heat is the conserved quantity | https://en.wikipedia.org/wiki?curid=39144241 |
Thermodynamic operation As a matter of history, the distinction, between a thermodynamic operation and a thermodynamic process, is not found in these terms in nineteenth century accounts. For example, Kelvin spoke of a "thermodynamic operation" when he meant what present-day terminology calls a thermodynamic operation followed by a thermodynamic process. Again, Planck usually spoke of a "process" when our present-day terminology would speak of a thermodynamic operation followed by a thermodynamic process. Planck held that all "natural processes" (meaning, in present-day terminology, a thermodynamic operation followed by a thermodynamic process) are irreversible and proceed in the sense of increase of entropy sum. In these terms, it would be by thermodynamic operations that, if he could exist, Maxwell's demon would conduct unnatural affairs, which include transitions in the sense away from thermodynamic equilibrium. They are physically theoretically conceivable up to a point, but are not natural processes in Planck's sense. The reason is that ordinary thermodynamic operations are conducted in total ignorance of the very kinds of microscopic information that is essential to the efforts of Maxwell's demon. A thermodynamic cycle is constructed as a sequence of stages or steps. Each stage consists of a thermodynamic operation followed by a thermodynamic process | https://en.wikipedia.org/wiki?curid=39144241 |
Thermodynamic operation For example, an initial thermodynamic operation of a cycle of a Carnot heat engine could be taken as the setting of the working body, at a known high temperature, into contact with a thermal reservoir at the same temperature (the hot reservoir), through a wall permeable only to heat, while it remains in mechanical contact with the work reservoir. This thermodynamic operation is followed by a thermodynamic process, in which the expansion of the working body is so slow as to be effectively reversible, while internal energy is transferred as heat from the hot reservoir to the working body and as work from the working body to the work reservoir. Theoretically, the process terminates eventually, and this ends the stage. The engine is then subject to another thermodynamic operation, and the cycle proceeds into another stage. The cycle completes when the thermodynamic variables (the thermodynamic state) of the working body return to their initial values. A refrigeration device passes a working substance through successive stages, overall constituting a cycle. This may be brought about not by moving or changing separating walls around an unmoving body of working substance, but rather by moving a body of working substance to bring about exposure to a cyclic succession of unmoving unchanging walls. The effect is virtually a cycle of thermodynamic operations | https://en.wikipedia.org/wiki?curid=39144241 |
Thermodynamic operation The kinetic energy of bulk motion of the working substance is not a significant feature of the device, and the working substance may be practically considered as nearly at rest. For many chains of reasoning in thermodynamics, it is convenient to think of the combination of two systems into one. It is imagined that the two systems, separated from their surroundings, are juxtaposed and (by a shift of viewpoint) regarded as constituting a new, composite system. The composite system is imagined amid its new overall surroundings. This sets up the possibility of interaction between the two subsystems and between the composite system and its overall surroundings, for example by allowing contact through a wall with a particular kind of permeability. This conceptual device was introduced into thermodynamics mainly in the work of Carathéodory, and has been widely used since then. If the thermodynamic operation is entire removal of walls, then extensive state variables of the composed system are the respective sums of those of the component systems. This is called the additivity of extensive variables. A thermodynamic system consisting of a single phase, in the absence of external forces, in its own state of internal thermodynamic equilibrium, is homogeneous. This means that the material in any region of the system can be interchanged with the material of any congruent and parallel region of the system, and the effect is to leave the system thermodynamically unchanged | https://en.wikipedia.org/wiki?curid=39144241 |
Thermodynamic operation The thermodynamic operation of "scaling" is the creation of a new homogeneous system whose size is a multiple of the old size, and whose intensive variables have the same values. Traditionally the size is stated by the mass of the system, but sometimes it is stated by the entropy, or by the volume. For a given such system , scaled by the real number to yield a new one , a state function, , such that , is said to be extensive. Such a function as is called a homogeneous function of degree 1. There are two different concepts mentioned here, sharing the same name: (a) the mathematical concept of degree-1 homogeneity in the scaling function; and (b) the physical concept of the spatial homogeneity of the system. It happens that the two agree here, but that is not because they are tautologous. It is a contingent fact of thermodynamics. If two systems, and , have identical intensive variables, a thermodynamic operation of wall removal can compose them into a single system, , with the same intensive variables. If, for example, their internal energies are in the ratio , then the composed system, , has internal energy in the ratio of to that of the system . By the inverse thermodynamic operation, the system can be split into two subsystems in the obvious way. As usual, these thermodynamic operations are conducted in total ignorance of the microscopic states of the systems | https://en.wikipedia.org/wiki?curid=39144241 |
Thermodynamic operation More particularly, it is characteristic of macroscopic thermodynamics that the probability vanishes, that the splitting operation occurs at an instant when system is in the kind of extreme transient microscopic state envisaged by the Poincaré recurrence argument. Such splitting and recomposition is in accord with the above defined additivity of extensive variables. Thermodynamic operations appear in the statements of the laws of thermodynamics. For the zeroth law, one considers operations of thermally connecting and disconnecting systems. For the second law, some statements contemplate an operation of connecting two initially unconnected systems. For the third law, one statement is that no finite sequence of thermodynamic operations can bring a system to absolute zero temperature. | https://en.wikipedia.org/wiki?curid=39144241 |
Crack tip opening displacement (CTOD) or formula_1 is the distance between the opposite faces of a crack tip at the 90° intercept position. The position behind the crack tip at which the distance is measured is arbitrary but commonly used is the point where two 45° lines starting at the crack tip intercept the crack faces. The parameter is used in fracture mechanics to characterise the loading on a crack and can be related to other crack tip loading parameters such as the stress intensity factor formula_2 and the elastic-plastic J-integral. Under fatigue loading, the range of movement of the crack tip during a loading cycle formula_3 can be used for determining the rate of fatigue growth using a crack growth equation. The crack extension for a cycle formula_4, is typically of the order of formula_3. Examination of fractured test specimens led to the observation that the crack faces had moved apart prior to fracture, due to the blunting of an initially sharp crack by plastic deformation. The degree of crack blunting increased in proportion to the toughness of the material. This observation led to considering the opening at the crack tip as a measure of fracture toughness. This parameter became known as CTOD. G. R. Irwin later postulated that crack-tip plasticity makes the crack behave as if it were slightly longer. Thus, estimation of CTOD can be done by solving for the displacement at the physical crack tip. CTOD is a single parameter that accommodates crack tip plasticity | https://en.wikipedia.org/wiki?curid=39145558 |
Crack tip opening displacement It is easy to measure when compared with techniques such as J integral. It is a fracture parameter that has more physical meaning than the rest. However, the equivalence of CTOD and J integral is proven only for non-linear materials, but not for plastic materials. It is hard to expand the concept of CTOD for large deformations. It is easier to calculate J-integral in case of a design process using finite element method techniques. CTOD can be expressed in terms of stress intensity factor formula_2 as where formula_8 is the yield strength, formula_9 is Young's modulus and formula_10 for plane stress and formula_11 for plane strain. The relationship between the CTOD and J is given by where the variable formula_13 is typically between 0.3 and 0.8. A CTOD test is usually done on materials that undergo plastic deformation prior to failure. The testing material more or less resembles the original one, although dimensions can be reduced proportionally. Loading is done to resemble the expected load. More than 3 tests are done to minimize any experimental deviations. The dimensions of the testing material must maintain proportionality. The specimen is placed on the work table and a notch is created exactly at the centre. The crack should be generated such that the defect length is about half the depth. The load applied on the specimen is generally a three-point bending load. A strain gauge is used to measure the crack opening | https://en.wikipedia.org/wiki?curid=39145558 |
Crack tip opening displacement Crack tip plastically deforms until a critical point after which a cleavage crack is initiated that may lead to either partial or complete failure. The critical load and strain gauge measurements at the load are noted and a graph is plotted. The crack tip opening can be calculated from the length of the crack and opening at the mouth of the notch. According to the material used, the fracture can be brittle or ductile which can be concluded from the graph. Early experiments used a flat, paddle-shaped gauge that was inserted into the crack; as the crack opens, the paddle gauge rotates and an electronic signal is sent to an x–y plotter. This method was inaccurate, however, because it was difficult to reach the crack tip with the paddle gauge. Today, the displacement V at the crack mouth is measured and the CTOD is inferred by assuming that the specimen halves are rigid and rotate about a hinge point. | https://en.wikipedia.org/wiki?curid=39145558 |
C13H14O3 The molecular formula CHO (molar mass: 218.248 g/mol) may refer to: | https://en.wikipedia.org/wiki?curid=39147681 |
Tunable resistive pulse sensing Tunable Resistive Pulse Sensing (TRPS) is a technique that allows high-throughput single particle measurements as colloids and/or biomolecular analytes driven through a size-tunable nanopore, one at a time. The technique adapts the principle of resistive pulse sensing, which monitors current flow through an aperture, combined with the use of tunable nanopore technology, allowing the passage of ionic current and particles to be regulated by adjusting the pore size. Particles crossing a pore are detected one at a time as a transient change in the ionic current flow, which is denoted as a blockade event with its amplitude denoted as the blockade magnitude. As blockade magnitude is proportional to particle size, accurate particle sizing can be achieved after calibration with a known standard. Nanopore-based detection allows particle-by-particle assessment of complex mixtures. Optimization of pore size to particle size, by adjusting the stretch of the pore, can improve measurement accuracy. Through combination with fine-control of pressure TRPS has been used to determine sample concentration and to accurately derive particle electrophoretic mobility & surface charge in addition to particle size information. TRPS has been applied in product development by nanotechnology instrument manufacturers Izon Science Ltd in the first commercially available nanopore-based particle characterization systems | https://en.wikipedia.org/wiki?curid=39154794 |
Tunable resistive pulse sensing These systems have been applied to measure a wide range of biological and synthetic particle types including viruses and nanoparticles. TRPS has been applied in both academic and industrial research fields, including: | https://en.wikipedia.org/wiki?curid=39154794 |
Mutatochrome (5,8-epoxy-β-carotene) is a carotenoid. It is the predominant carotenoid in the cap of the bolete mushroom "Boletus luridus". | https://en.wikipedia.org/wiki?curid=39158997 |
Rhodopin (1,2-dihydro-ψ,ψ-caroten-1-ol) is a carotenoid. It is a major carotenoid of phototropic bacteria such as "Rhodomicrobium vannielii" and "Rhodopseudomonas acidophila" strain 7050. | https://en.wikipedia.org/wiki?curid=39161330 |
Synthesis of nanoparticles by fungi Throughout human history, fungi have been utilized as a source of food and harnessed to ferment and preserve foods and beverages. In the 20th century, humans have learned to harness fungi to protect human health (antibiotics, anti-cholesterol statins, and immunosuppressive agents), while industry has utilized fungi for large scale production of enzymes, acids, and biosurfactants. With the advent of modern nanotechnology in the 1980s, fungi have remained important by providing a greener alternative to chemically synthesized nanoparticle. A nanoparticle is defined as having one dimension 100 nm or less in size. Environmentally toxic or biologically hazardous reducing agents are typically involved in the chemical synthesis of nanoparticles so there has been a search for greener production alternatives. Current research has shown that microorganisms, plant extracts, and fungi can produce nanoparticles through biological pathways. The most common nanoparticles synthesized by fungi are silver and gold, however fungi have been utilized in the synthesis other types of nanoparticles including zinc oxide, platinum, magnetite, zirconia, silica, titanium, and cadmium sulfide and cadmium selenide quantum dots. Synthesis of silver nanoparticles has been investigated utilizing many ubiquitous fungal species including "Trichoderma", "Fusarium", "Penicillium", "Rhizoctonia", "Pleurotus" and "Aspergillus". Extracellular systhesis has been demonstrated by "Trichoderma virde", "T. reesei", "Fusarium oxysporm", "F. semitectum", "F | https://en.wikipedia.org/wiki?curid=39169481 |
Synthesis of nanoparticles by fungi solani", "Aspergillus niger", "A. flavus", "A. fumigatus", "A. clavatus", "Pleurotus ostreatus", "Cladosporium cladosporioides", "Penicillium brevicompactum", "P. fellutanum", an endophytic "Rhizoctonia" sp., "Epicoccum nigrum", "Chrysosporium tropicum", and "Phoma glomerata", while intracellular synthesis was shown to occur in a "Verticillium" species, and in "Neurospora crassa". Synthesis of gold nanoparticles has been investigated utilizing "Fusarium", "Neurospora", "Verticillium", yeasts, and "Aspergillus". Extracellular gold nanoparticle synthesis was demonstrated by "Fusarium oxysporum", "Aspergillus niger", and cytosolic extracts from "Candida albican". Intracellular gold nanoparticle synthesis has been demonstrated by a "Verticillum" species, "V. luteoalbum", In addition to gold and silver, "Fusarium oxysporum" has been used to synthesize zirconia, titanium, cadmium sulfide and cadmium selenide nanosize particles. Cadmium sulfide nanoparticles have also been synthesized by "Trametes versicolor", "Schizosaccharomyces pombe", and "Candida glabrata". The white-rot fungus "Phanerochaete chrysosporium" has also been demonstrated to be able to synthesize elemental selenium nanoparticles. Culture techniques and media vary depending upon the requirements of the fungal isolate involved, however the general procedure consist of the following: fungal hyphae are typically placed in liquid growth media and placed in shake culture until the fungal culture has increased in biomass | https://en.wikipedia.org/wiki?curid=39169481 |
Synthesis of nanoparticles by fungi The fungal hyphae are removed from the growth media, washed with distilled water to remove the growth media, placed in distilled water and incubated on shake culture for 24 to 48 hours. The fungal hyphae are separated from the supernatant, and an aliquot of the supernatant is added to 1.0 mM ion solution. The ion solution is then monitored for 2 to 3 days for the formation of nanoparticles. Another common culture technique is to add washed fungal hyphae directly into 1.0 mM ion solution instead of utilizing the fungal filtrate. Silver nitrate is the most widely used source of silver ions, but silver sulfate has also been utilized. Choloroauric acid is generally used as the source of gold ions at various concentrations (1.0 mM and 250 mg to 500 mg of Au per liter). Cadmium sulfide nanoparticle synthesis for "F. oxysporum" was conducted using a 1:1 ratio of Cd and SO at a 1 mM concentration. Gold nanoparticles can vary in shape and size depending on the pH of the ion solution. Gericke and Pinches (2006) reported that for "V. luteoalbum" small (cc.10 nm) spherical gold nanoparticles are formed at pH 3, larger (spherical, triangular, hexagon and rods) gold nanoparticles are formed at pH 5, and at pH 7 to pH 9 the large nanoparticles tend to lack a defined shape. Temperature interactions for both silver and gold nanoparticles were similar; a lower temperature resulted in larger nanoparticles while higher temperatures produced smaller nanoparticles | https://en.wikipedia.org/wiki?curid=39169481 |
Synthesis of nanoparticles by fungi For externally synthesized silver nanoparticles the silver ion solution generally becomes brownish in color, but this browning reaction may be absent. For fungi that synthesize intracellular silver nanoparticles, the hyphae darken to a brownish color while the solution remains clear. In both cases the browning reaction is attributed to the surface plasmon resonance of the metallic nanoparticles. For external gold nanoparticle production, the solution color can vary depending on the size of the gold nanoparticles; smaller particles appear pink while large particles appear purple. Intracellular gold nanoparticle synthesis typically turns the hyphae purple while the solution remains clear. Externally synthesized cadmium sulfide nanoparticles were reported to make the solution color appear bright yellow. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive analysis of X-ray (EDX), UV-vis spectroscopy, and X-ray diffraction are used to characterize different aspects of nanoparticles. Both SEM and TEM can be used to visualize the location, size, and morphology of the nanoparticles, while UV-vis spectroscopy can be used to confirm the metallic nature, size and aggregation level. Energy dispersive analysis of X-ray is used to determine elemental composition, and X-ray diffraction is used to determine chemical composition and crystallographic structure | https://en.wikipedia.org/wiki?curid=39169481 |
Synthesis of nanoparticles by fungi UV-Vis absorption peaks for silver, gold, and cadmium sulfide nanoparticles can vary depending on particle size: 25-50 nm silver particles peak ca. 415 nm, gold nanoparticles 30-40 nm peak ca. 450 nm, while a cadmium sulfide absorption edge ca. 450 is indicative of quantum size particles. Larger nanoparticle of each type will have UV-Vis absorption peaks or edges that shift to longer wavelengths while smaller nanoparticles will have UV-Vis absorption peaks or edges that shift to shorter wavelengths. Nitrate reductase was suggested to initiate nanoparticle formation by many fungi including "Penicillium" species, while several enzymes, α-NADPH-dependent reductases, nitrate-dependent reductases and an extracellular shuttle quinone, were implicated in silver nanoparticle synthesis for "Fusarium oxysporum". Jain et al. (2011) indicated that silver nanoparticle synthesis for "A. flavus" occurs initially by a "33kDa" protein followed by a protein (cystein and free amine groups) electrostatic attraction which stabilizes the nanoparticle by forming a capping agent. Intracellular silver and gold nanoparticle synthesis is not fully understood but similar fungal cell wall surface electrostatic attraction, reduction, and accumulation has been proposed. External gold nanoparticle synthesis by "P. chrysosporium" was attributed to laccase, while intracellular gold nanoparticle synthesis was attributed to ligninase | https://en.wikipedia.org/wiki?curid=39169481 |
Synthesis of nanoparticles by fungi Cadmium sulfide nanoparticle synthesis by yeast involves sequestration of Cd by glutathione-related peptides followed by reduction within the cell. Ahmad et al. (2002) reported that cadmium sulfide nanoparticle synthesis by "Fusarium oxysporum" was based on a sulfate reductase (enzyme) process. | https://en.wikipedia.org/wiki?curid=39169481 |
Salvador Imperatore Marcone (born 11 March 1950) is a Chilean former football referee. He officiated the opening match at the 1991 FIFA Women's World Cup, as well as the semi final between the United States and Germany. He was later on call as a reserve official for the 1994 FIFA World Cup. Imperatore also refereed at the 1993 FIFA U-17 World Championship, the 1995 Copa América and the 1995 King Fahd Cup. A chemical engineer by trade, Imperatore suffered a stroke in 2008. | https://en.wikipedia.org/wiki?curid=39178279 |
Magnetic spin vortex disc Magnetic material synthesis and characterization technology continue to improve, allowing for the production of various shapes, sizes, and compositions of magnetic material to be studied and tuned for improved properties. One of the places which has seen great advancement is in the synthesis of magnetic materials at nanometer length scales. Pedro Alexandre Lino Silva made 'experimental proof of magnetic vortex'. Nanoparticle research has seen a great deal of interest in a number of fields as many phenomena can be explained by what is occurring on the nanoscale, which can be probed more effectively using nanometer sized materials. One unique type of materials which have seen a recent surge in research interest have been known as "nanoflakes" where they resemble flakes or discs of nanometer thickness and micrometer dimensions. Nanomaterials of this shape have seen use in a number of fields including energy storage, as [electrodes] of electrochemical cells, and in cancer therapy to kill cancer cells. | https://en.wikipedia.org/wiki?curid=39179456 |
Early Japanese iron-working techniques Blast furnaces are thought by many scholars to have developed independently in Western Europe and China, albeit many centuries earlier in the latter. The blast furnace was essential to the development of steel and cast iron, as it allowed much higher temperatures to be reached than its predecessor, the bloomery. Since the blast furnace temperatures were able to exceed 1,536 C, the melting point of iron, the resulting product had significantly less slag (higher purity) than the iron produced by the bloomery. Furthermore, because the temperatures were so low in the bloomeries, only low-carbon steel was able to be produced (wrought iron). As the bloomery began to gradually evolve into the blast furnace during the Middle Ages, many variations on the basic concept began to emerge globally. The traditional Japanese furnace, known as a “tatara”, was a hybrid type of furnace. It incorporated bellows, like the European blast furnace, but was constructed of clay; these furnaces would eventually be destroyed after the first use. According to existing archeological records, the first tataras were built during the middle part of the sixth century A.D. Due to the large scale of the tatara, as compared to its European, Indian and Chinese counterparts, the temperature at a given point would vary based on the height in the furnace | https://en.wikipedia.org/wiki?curid=39181486 |
Early Japanese iron-working techniques Therefore, different types of iron could be found at different heights inside the furnace, ranging from wrought iron at the top of the tatara (furthest from the heat, lowest temperature), to cast iron towards the middle, and finally steel towards the bottom (with varying degrees of carbon content.) Importantly, tataras did not exceed 1500 C, so they did not completely melt the iron. The metal-workers clearly had an understanding of the differences between the various types of iron found in the tatara, and they separated out and selected different portions of the “bloom” accordingly. In katana forging, for example, only the high- and low- carbon blooms were selected for use. The swordsmiths would then forge the two types of blooms into larger sheets, pound the sheets, fold them on themselves, then repeat this process a minimum of 10 times. Although the chemical process was unknown to them, they were effectively distributing the carbon content of the steel evenly throughout the product, and also distributing the impurities more evenly. This resulted in a product of excellent strength, which had a carbon content higher than that of contemporary European works, but not as high as those found in Indian artifacts. The tatara bloomery method is considered by historians and archeologists to be unique, and more specifically “an exotic outlier of mainstream metallurgical development.” It has been suggested by scholars that this technology was initially imported from Korea, but the evidence for this is not overwhelming | https://en.wikipedia.org/wiki?curid=39181486 |
Early Japanese iron-working techniques We can, however, conclude that the Japanese bloomery with its linear design, (in contrast to circular European blast furnaces) certainly resembles many contemporary South Asian designs. The etymology of “tatara” is not Japanese in its origin, which supports the theory that this technology was not locally synthesized. However, after its adoption, this technology was indeed adapted for local use. While the tatara has commonalities with other South Asian furnace designs, including those of Sri Lanka and Cambodia, the local materials for use in the blast furnace were remarkably different. The main source of ores for Japanese steel was iron sand, a sand-like substance which accumulated as an end product of the erosion of granite and andesite in mountainous regions of Japan. Importantly, it was less labor-intensive to extract the ore from the sand than from hard rock. Furthermore, this sand could be obtained by surface mining, rather than more laborious mining process. However, these sands had a much lower percentage of iron than that typically found in rock-ores, only 2-5% Ferrous Oxide, as compared to 79-87% Ferrous Oxide in certain Sri Lankan ores, for example. Since this smaller percentage of iron would inevitably lead to smaller blooms, Japanese metal workers would have been very familiar with the process of combining blooms | https://en.wikipedia.org/wiki?curid=39181486 |
Early Japanese iron-working techniques Given these environmental constraints, the most effective solution was to combine certain types of blooms, and through trial-and-error, early sword smiths were able to determine that the most effective combinations of blooms (for swords) were those at the bottom of the tatara. Grazzi, F., Civita, F., Williams, A., Scherillo, A., Barzagli, E., Bartoli, L., Edge, D., & Zoppi, M. (2011). Ancient and historic steel in Japan, India and Europe, a non-invasive comparative study using thermal neutron diffraction. Analytical and Bioanalytical Chemistry, 400(5), 1493-1500. doi: 10.1007/s00216-011-4854-1 Inoue, T. (2009). Tatara and the Japanese sword: the science and technology. Acta Mechanica, 214(N1-2), 17-30. doi: 10.1007/s00707-010-0308-7 Juleff, G. (2009). Technology and evolution: a root and branch view of Asian iron from first-millennium bc Sri Lanka to Japanese steel. World Archeology, 41(4), 557-577. doi: 10.1080/00438240903345688 Wittner, D. (2007). Technology and the culture of progress in meiji Japan. (pp. 24–26). New York, NY: Routledge. | https://en.wikipedia.org/wiki?curid=39181486 |
Soluble adenylyl cyclase (sAC) is a regulatory cytosolic enzyme present in almost every cell. sAC is a source of cyclic adenosine 3’,5’ monophosphate (cAMP) – a second messenger that mediates cell growth and differentiation in organisms from bacteria to higher eukaryotes. sAC differentiates from the transmembrane adenylyl cyclase (tmACs) – an important source of cAMP; in that sAC is regulated by bicarbonate anions and it is dispersed throughout the cell cytoplasm. sAC has been found to have various functions in physiological systems different from that of the tmACs. sAC is encoded in a single Homo sapiens gene identified as ADCY10 or Adenylate cyclase 10 (soluble). This gene packed down 33 exons that comprise greater than 100kb; though, it seems to utilize multiple promoters, and its mRNA undergoes extensive alternative splicing. The functional mammalian sAC consist of two heterologous catalytic domains (C1 and C2), forming the 50 kDa amino terminus of the protein. The additional ~140 kDa C terminus of the enzyme includes an autoinhibitory region, canonical P-loop, potential heme-binding domain, and leucine zipper-like sequence, which are a form of putative regulatory domains. A truncated form of the enzyme only includes the C1 and C2 domains and it is refers to as the minimal functional sAC variant. This sAC-truncated form has cAMP-forming activity much higher than its full-length type. These sAC variants are stimulated by HCO3- and respond to all known selective sAC inhibitors | https://en.wikipedia.org/wiki?curid=39192470 |
Soluble adenylyl cyclase Crystal structures of this sAC variant comprising only the catalytic core, in apo form and in as complex with various substrate analogs, products, and regulators, reveal a generic Class III AC architecture with sAC-specific features. The structurally related domains C1 and C2 form the typical pseudo-heterodimer, with one active site. The pseudo-symmetric site accommodates the sAC-specific activator HCO3−, which activates by triggering a rearrangement of Arg176, a residue connecting both sites. The anionic sAC inhibitor 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS) acts as a blocker for the entrance to active site and bicarbonate binding pocket. The binding and cyclizing of adenosine 5’ triphosphate (ATP) to the catalytic active site of the enzyme is coordinated by two metal cations. The catalytic activity of sAC is increase by the presence of manganese [Mn]. sAC magnesium [Mg] activity is regulated by calcium [Ca] which increases the affinity for ATP of mammalian sAC. In addition, bicarbonate [HCO] releases ATP-Mg substrate inhibition and increases V of the enzyme. The open conformation state of sAC is reached when ATP, with Ca bound to its γ-phosphate binds with specific residues in the catalytic center of the enzyme. When the second metal – a Mg ion – binds to the α-phosphate of ATP leads to a conformational change of the enzyme: "the close state" | https://en.wikipedia.org/wiki?curid=39192470 |
Soluble adenylyl cyclase The change in conformation from open to close state induces esterification of the α-phosphate with the ribose in adenosine and the release of the β- and γ-phosphates, this leads to cyclizing. Hydrogencarbonate stimulates the enzyme’s V by promoting the allosteric change that leads to active site closure, recruitment of the catalytic Mg ion, and readjustment of the phosphates in the bound ATP. The activator bicarbonate binds to a site pseudo-symmetric to the active site and triggers conformational changes by recruiting Arg176 from the active site (see above - "structure"). Calcium increases substrate affinity by replacing the magnesium in the ion B site, which provides an anchoring point for the beta- and gamma-phosphates of the ATP substrate. Astrocytes express several sAC splice variants, which are involved in metabolic coupling between neurons and astrocytes. Increase of potassium [K] in the extracellular space caused by neuronal activity depolarizes the cell membrane of nearby astrocytes and facilitates the entry of hydrogencarbonate through Na/HCO- cotransporters. The increase in cytosolic hydrogencarbonate activates sAC; the result of this activation is the release of lactate for use as energy source by the neurons. Numerous sAC splice variants are present in osteoclast and osteoblasts, and mutation in the human sAC gene is associated with low spinal density. Calcification by osteoblasts is intrinsically related with bicarbonate and calcium | https://en.wikipedia.org/wiki?curid=39192470 |
Soluble adenylyl cyclase Bone density experiments in mouse calvaria cultured indicates that HCO-sensing sAC is a physiological appropriate regulator of bone formation and/or reabsorption. sAC activation by bicarbonate necessary for motility and other aspects of capacitation in the spermatozoa of mammals. | https://en.wikipedia.org/wiki?curid=39192470 |
Non-ferrous extractive metallurgy is one of the two branches of extractive metallurgy which pertains to the processes of reducing valuable, non-iron metals from ores or raw material. Metals like zinc, copper, lead, aluminium as well as rare and noble metals are of particular interest in this field, while the more common metal, iron, is considered a major impurity. Like ferrous extraction, non-ferrous extraction primarily focuses on the economic optimization of extraction processes in separating qualitatively and quantitatively marketable metals from its impurities (gangue). Any extraction process will include a sequence of steps or unit processes for separating highly pure metals from undesirables in an economically efficient system. Unit processes are usually broken down into three categories: pyrometallurgy, hydrometallurgy, and electrometallurgy. In pyrometallurgy, the metal ore is first oxidized through roasting or smelting. The target metal is further refined at high temperatures and reduced to its pure form. In hydrometallurgy, the object metal is first dissociated from other materials using a chemical reaction, which is then extracted in pure form using electrolysis or precipitation. Finally, electrometallurgy generally involves electrolytic or electrothermal processing. The metal ore is either distilled in an electrolyte or acid solution, then magnetically deposited onto a cathode plate (electrowinning); or smelted then melted using an electric arc or plasma arc furnace (electrothermic reactor) | https://en.wikipedia.org/wiki?curid=39197996 |
Non-ferrous extractive metallurgy Another major difference in non-ferrous extraction is the greater emphasis on minimizing metal losses in slag. This is widely due to the exceptional scarcity and economic value of certain non-ferrous metals which are, inevitably, discarded during the extraction process to some extent. Thus, material resource scarcity and shortages are of great concern to the non-ferrous industry. Recent developments in non-ferrous extractive metallurgy now emphasize the reprocessing and recycling of rare and non-ferrous metals from secondary raw materials (scrap) found in landfills. In general, prehistoric extraction of metals, particularly copper, involved two fundamental stages: first, the smelting of copper ore at temperatures exceeding 700 °C is needed to separate the gangue from the copper; second, melting the copper, which requires temperatures exceeding its melting point of 1080 °C. Given the available technology at the time, accomplishing these extreme temperatures posed a significant challenge. Early smelters developed ways to effectively increase smelting temperatures by feeding the fire with forced flows of oxygen. Copper extraction in particular is of great interest in archeometallurgical studies since it dominated other metals in Mesopotamia from the early Chalcolithic until the mid-to-late sixth century BC. There is a lack of consensus among archaeometallurgists on the origin of non-ferrous extractive metallurgy | https://en.wikipedia.org/wiki?curid=39197996 |
Non-ferrous extractive metallurgy Some scholars believe that extractive metallurgy may have been simultaneously or independently discovered in several parts of the world. The earliest known use of pyrometallurgical extraction of copper occurred in Belovode, eastern Serbia, from the late sixth to early fifth millennium BC. However, there is also evidence of copper smelting in Tal-i-Iblis, southeastern Iran, which dates back to around the same period. During this period, copper smelters used large in-grown pits filled with coal, or crucibles to extract copper, but by the fourth millennium BC this practice had begun to phase out in favor of the smelting furnace, which had a larger production capacity. From the third millennium onward, the invention of the reusable smelting furnace was crucial to the success of large-scale copper production and the robust expansion of the copper trade through the Bronze Age. The earliest silver objects began appearing in the late fourth millennium BC in Anatolia, Turkey. Prehistoric silver extraction is strongly associated with the extraction of the less valuable metal, lead; although evidence of lead extraction technology predates silver by at least 3 millennia. Silver and lead extractions are also associated because the argentiferous (silver-bearing) ores used in the process often contains both elements. In general, prehistoric silver recovery was broken down into three phases: First, the silver-lead ore is roasted to separate the silver and lead from the gangue | https://en.wikipedia.org/wiki?curid=39197996 |
Non-ferrous extractive metallurgy The metals are then melted at high temperature ( greater than 1100 °C) in the crucible while air is blown over the molten metal (cupellation). Finally, lead is oxidized to form lead monoxide (PbO) or is absorbed into the walls of the crucible, leaving the refined silver behind. The silver-lead cupellation method was first used in Mesopotamia between 4000 and 3500 BC. Silver artifacts, dating around 3600 BC, were discovered in Naqada, Egypt. Some of these cast silver artifacts contained less than 0.5% lead, which strongly indicates cupellation. Cupellation was also being used in parts of Europe to extract gold, silver, zinc, and tin by the late ninth to tenth century AD. Here, one of the earliest examples of an integrated unit process for extracting more than one precious metal was first introduced by Theophilus around the twelfth century. First, the gold-silver ore is melted down in the crucible, but with an excess amount of lead. The intense heat then oxidizes the lead which reacts quickly and binds with the impurities in the gold-silver ore. Since both gold and silver have low reactivity with the impurities, they remain behind once the slag is removed. The last stage involves parting, in which the silver is separated from the gold. First the gold-silver alloy is hammered into thin sheets and placed into a vessel. The sheets were then covered in urine, which contains sodium chloride (NaCl) | https://en.wikipedia.org/wiki?curid=39197996 |
Non-ferrous extractive metallurgy The vessel is then capped and heated for several hours until the chlorides bind with the silver, creating silver chloride (AgCl). Finally, the silver chloride powder is then removed and smelted to recover the silver, while the pure gold remains intact. During the Song Dynasty, Chinese copper output from domestic mining was in decline and the resulting shortages caused miners to seek alternative methods for extracting copper. The discovery of a new “wet process” for extracting copper from mine water was introduced between the eleventh and twelfth century, which helped to mitigate their loss of supply. Similar to the Anglo-Saxon method for cupellation, the Chinese employed the use of a base metal to extract the target metal from its impurities. First, the base metal, iron, is hammered into thin sheets. The sheets are then placed into a trough filled with “vitriol water” i.e., copper mining water which is then left to steep for several day. The mining water contains copper salts in the form of copper sulfate . The iron then reacts with the copper, displacing it from the sulfate ions, causing the copper to precipitate onto the iron sheets, forming a "wet" powder. Finally, the precipitated copper is collected and refined further through the traditional smelting process. This is the first large-scale use of a hydrometallurgical process. | https://en.wikipedia.org/wiki?curid=39197996 |
Timir Datta is an Indian-American physicist specializing in high transition temperature superconductors and a professor of physics in the department of Physics and Astronomy at the University of South Carolina, in Columbia, South Carolina. Datta grew up in India along with elder brother Jyotirmoy Datta a noted journalist; his father B.N. Dutt a scion of two land owning families from Khulna and Jessore in south central Bengal (British India) was an eminent sugar-refining engineer and on his mother's side a relative of Michael Madhushudan Dutt the famed poet. He received a master's degree in theoretical plasma physics from Boston College in 1974 under the direction of Gabor Kalman. Datta also worked at the Jet Propulsion laboratory (JPL) in Pasadena, California, as a pre-doctoral NASA research associate of Robert Somoano. He also collaborated with Carl H. Brans at Loyola University New Orleans on a gravitational problem of frame dragging and worked with John Perdew on the behavior of charge density waves in jellium. Datta was a NSF post-doctoral fellow with Marvin Silver and studied charge propagation in non-crystalline systems at the University of North Carolina in Chapel Hill. At UNC-CH he continued his theoretical interests and worked on retarded Vander Waals potential with L. H. Ford. Since 1982, he has been on the faculty of the University of South Carolina in Columbia | https://en.wikipedia.org/wiki?curid=39198217 |
Timir Datta He collaborated with several laboratories involved with the early discoveries of high temperature superconductivity, especially the team at NRL, led by Donald U Gubser and Stuart Wolf. This research group at USC was the also first to observe (i) bulk Meissner effect in Tl-copper oxides and thus confirm the discovery by Allen Herman's team at the University of Arkansas of high temperature superconductivity in these compounds. He coined the term "triple digit superconductivity", and his group was the first to observe (ii) fractional quantum hall effect in 3-dimensional carbon. In a paper with Raphael Tsu he derived the first quantum mechanical wave impedance formula for Schrödinger wave functions. He was also the first to show that Bragg's law of X-ray scattering from crystals is a direct consequence of Euclidean length invariance of the incident wave vector; in fact Max von Laue's three diffraction equations are not independent but related by length conservation. Datta is an active researcher, with over 100 papers listed in the SAO/NASA Astrophysics Data System (ADS) as of 2014. Datta was issued one US patent in 1995: "Flux-trapped superconducting magnets and method of manufacture", with two co-inventors. Datta was involved in the university-funded development of a "Gravity Generator" in 1996 and 1997, with then-fellow university researcher Douglas Torr | https://en.wikipedia.org/wiki?curid=39198217 |
Timir Datta According to a leaked document from the Office of Technology Transfer at the University of South Carolina and confirmed to "Wired" reporter Charles Platt in 1998, the device would create a "force beam" in any desired direction and the university planned to patent and license this device. Neither information about this university research project nor any "Gravity Generator" device was ever made public. Despite the apparent less than successful outcome of the "Gravity Generator" development effort with Torr, Datta became interested in the effects of electric fields on gravitation, expanding on Torr's theoretical work on the subject. | https://en.wikipedia.org/wiki?curid=39198217 |
Zircotec is a high temperature coating and heat barrier manufacturer, based in Abingdon near Oxford, England. It uses plasma-sprayed ceramic materials to provide thermal and abrasive resistance to components - with a focus on automotive exhaust systems. Its best-known products include coloured thermal barrier coatings and Zircoflex - a flexible ceramic heatshield. began life as part of the United Kingdom Atomic Energy Authority, where its high temperature coatings and heat barrier processes were originally developed for the nuclear industry. It was based at the Atomic Energy Research Establishment near Harwell, Oxfordshire. At the time, this was the main centre for atomic energy research and development in the United Kingdom. In 1994, Zircotec's thermal barrier coatings were first used in a motorsport application. These coatings were applied to the exhaust systems of Subaru rally cars to lower in-cabin temperatures. After initial success, these high temperature coatings were then used on a variety of other vehicles, including Formula One cars and trucks. was bought by a venture capital fund in 2003. Subsequently, shifted its focus from the nuclear industry, towards general industry and automotive applications. As a result, developed Thermohold coatings for high performance automotive and classic car applications. Their main Thermohold coating was called Performance White, a white dual-layer plasma-sprayed ceramic. In July 2007, Terry Graham was appointed as the new managing director | https://en.wikipedia.org/wiki?curid=39200647 |
Zircotec Later that year, high performance sportscar manufacturer Koenigsegg announced it would be using coatings on its CCX supercar. Additionally, in October, became involved in the world land speed steam-car record attempt, supplying its coatings for thermal protection of sensitive components - this attempt was successful a year later. In June 2008, developed a plasma-sprayed ceramic coating specifically for composite materials. Predominantly aimed at motorsport and high-performance car applications, coated composites could now function at temperatures above their melting points. In September 2008, launched its Performance Colours range. This range is based on Zircotec's Performance White coating, but has an additional coloured finish - offering a more robust and maintainable finish. initially released thirteen different colours, with plans to increase this variety over the next few years. Zircotec's directors completed a management buyout early in 2009. In 2010, the company's headquarters were relocated to the nearby town of Abingdon, Oxfordshire. The move was completed to provide increased production capacity and to accommodate future business growth. In 2011, developed the world's first flexible ceramic heatshield, named Zircoflex. Zircotec's Performance Range is based on its Thermohold coating. Each coating consists of a ceramic based material, plasma-sprayed in two layers onto the component. This coating is predominantly used for thermal insulation, thermal protection and its anti-wear properties | https://en.wikipedia.org/wiki?curid=39200647 |
Zircotec When used on an automotive exhaust system, exhaust skin temperature and under-bonnet temperature have been reduced by 33% and 50 °C, respectively. The range contains fifteen individual coatings - one white coating (Performance White), and fourteen coloured coatings (Performance Colours). The Performance Colours coatings are identical to the Performance White coating, but consist of an additional coloured top layer - offering a more robust and maintainable finish. The Performance White coating is suitable for temperatures of up to 1400 °C, whilst Performance Colours can be used up to 900 °C. The current colours on offer are as follows: Graphite, Solid Black, Metallic Black, Alaskan Blue, Warm Grey, Antique Silver, Sterling Silver, Chilled Red, Yellow Gold, Copper, Aqua Green, Fern Green, Aged Brown and Ultra Blue. Zircotec's primary range was developed as a lower cost derivative of its Thermohold coatings. Suitable up to 900 °C, it offers less thermal performance to the Performance Range with a 25% reduction in exhaust system temperatures. Currently only offers a black finish, but there are plans to make more colours available. Zircoflex is a flexible aluminium-backed ceramic heat-shield, claimed to be the first-ever such product. Based on a derivative of Zircotec's Thermohold coating, close-packed ceramic platelets are plasma-sprayed onto an aluminium foil. This allows tight folding of the heat-shield through 180°, whilst still maintaining thermal protection. Zircoflex is 0.25mm thick and lightweight at 460g/m | https://en.wikipedia.org/wiki?curid=39200647 |
Zircotec The heat-shield is useful at temperatures up to 500 °C. offers a plasma-sprayed ceramic coating specifically for composite materials. Commonly used on CFRP, this coating protects against heat, fire and abrasion. manufactures a number of different industrial ceramic components. Some examples are as follows: | https://en.wikipedia.org/wiki?curid=39200647 |
American Brass Superfund site The is a former industrial site, located in Henry County, Alabama. American Brass Inc. (ABI) operated a brass smelter and foundry facility on the site between 1978-1992. Prior to its closure in December 1992, the company had been cited by the United States Environmental Protection Agency (EPA), and the Alabama Department of Environmental Management, (ADEM), on several occasions for Resource Conservation and Recovery Act (RCRA) violations, arising from its waste and hazardous waste disposal processes. Site surveys, conducted by ADEM after ABI ceased operations, revealed stockpiles of 150,000 tons of contaminated waste, and extensive soil and groundwater contamination. After assessment by the EPA, it was added to the National Priorities List, in May 1999, for long-term remedial action. | https://en.wikipedia.org/wiki?curid=39207332 |
C15H20O5 The molecular formula CHO (molar mass: 280.316 g/mol) may refer to: | https://en.wikipedia.org/wiki?curid=39207575 |
Contactin Contactins are a subgroup of molecules belonging to the immunoglobulin superfamily that are expressed exclusively in the nervous system. These proteins are attached to the neuronal membrane by a GPI-anchor. The subgroup consists of six members now referred to as contactin 1-6, but historically they had different names as shown in the table below: | https://en.wikipedia.org/wiki?curid=39208322 |
Freeze-casting Freeze-casting, also frequently referred to as "ice-templating", is a technique that exploits the highly anisotropic solidification behavior of a solvent (generally water) in a well-dispersed slurry to template controllably a directionally porous ceramic. By subjecting an aqueous slurry to a directional temperature gradient, ice crystals will nucleate on one side of the slurry and grow along the temperature gradient. The ice crystals will redistribute the suspended ceramic particles as they grow within the slurry, effectively templating the ceramic. Once solidification has ended, the frozen, templated ceramic is placed into a freeze-dryer to remove the ice crystals. The resulting green body contains anisotropic macropores in a replica of the sublimated ice crystals and micropores found between the ceramic particles in the walls. This structure is often sintered to consolidate the particulate walls and provide strength to the porous material. The porosity left by the sublimation of solvent crystals is typically between 2–200 μm. The first observation of cellular structures resulting from the freezing of water goes back over a century, but the first reported instance of freeze-casting, in the modern sense, was in 1954 when Maxwell et al. attempted to fabricate turbosupercharger blades out of refractory powders. They froze extremely thick slips of titanium carbide, producing near-net-shape castings that were easy to sinter and machine. The goal of this work, however, was to make dense ceramics | https://en.wikipedia.org/wiki?curid=39211211 |
Freeze-casting It was not until 2001, when Fukasawa et al. created directionally porous alumina castings, that the idea of using freeze-casting as a means of creating novel porous structures really took hold. Since that time, research has grown considerably with hundreds of papers coming out within the last decade. Because freeze-casting is a physical process, the techniques developed for one material system can be applied to a wide range of materials. Additionally, due to the inordinate amount of control and broad range of possible porous microstructures that freeze-casting can produce, the technique has found its niche in a number of disparate fields such as tissue scaffolds, photonics, metal-matrix composites, dentistry, materials science, and even food science There are three possible end results to uni-directionally freezing a suspension of particles. First, the ice-growth proceeds as a planar front, pushing particles in front like a bulldozer pushes a pile of rocks. This scenario usually occurs at very low solidification velocities (< 1 μm s) or with extremely fine particles because they can move by Brownian motion away from the front. The resultant structure contains no macroporosity. If one were to increase the solidification speed, the size of the particles or solid loading moderately, the particles begin to interact in a meaningful way with the approaching ice front. The result is typically a lamellar or cellular templated structure whose exact morphology depends on the particular conditions of the system | https://en.wikipedia.org/wiki?curid=39211211 |
Freeze-casting It is this type of solidification that is targeted for porous materials made by freeze-casting. The third possibility for a freeze-cast structure occurs when particles are given insufficient time to segregate from the suspension, resulting in complete encapsulation of the particles within the ice front. This occurs when the freezing rates are rapid, particle size becomes sufficiently large, or when the solids loading is high enough to hinder particle motion. To ensure templating, the particles must be ejected from the oncoming front. Energetically speaking, this will occur if there is an overall increase in free energy if the particle were to be engulfed "(Δσ > 0)". formula_1 where "Δσ" is the change in free energy of the particle, σ is the surface potential between the particle and interface, "σ" is the potential between the particle and the liquid phase and "σ" is the surface potential between the solid and liquid phases. This expression is valid at low solidification velocities, when the system is shifted only slightly from equilibrium. At high solidification velocities, kinetics must also be taken into consideration. There will be a liquid film between the front and particle to maintain constant transport of the molecules which are incorporated into the growing crystal. When the front velocity increases, this film thickness "(d)" will decrease due to increasing drag forces. A critical velocity "(v)" occurs when the film is no longer thick enough to supply the needed molecular supply | https://en.wikipedia.org/wiki?curid=39211211 |
Freeze-casting At this speed the particle will be engulfed. Most authors express v as a function of particle size where formula_2. The transition from a porous R (lamellar) morphology to one where the majority of particles are entrapped occurs at "v", which was defined by Deville et al. to be: formula_3 where "a" is the average intermolecular distance of the molecule that is freezing within the liquid, "d" is the overall thickness of the liquid film, "η" is the solution viscosity, "R" is the particle radius and "z" is an exponent that can vary from 1 to 5. As expected, we see that "v" decreases as particle radius "R" goes up. Waschkies et al. studied the structure of dilute to concentrated freeze-casts from low (< 1 μm s) to extremely high (> 700 μm s) solidification velocities. From this study, they were able to generate morphological maps for freeze-cast structures made under various conditions. Maps such as these are excellent for showing general trends, but they are quite specific to the materials system from which they were derived. For most applications where freeze-casts will be used after freezing, binders are needed to supply strength in the green state. The addition of binder can significantly alter the chemistry within the frozen environment, depressing the freezing point and hampering particle motion leading to particle entrapment at speeds far below the predicted "v" | https://en.wikipedia.org/wiki?curid=39211211 |
Freeze-casting Assuming, however, that we are operating at speeds below v and above those which produce a planar front, we will achieve some cellular structure with both ice-crystals and walls composed of packed ceramic particles. The morphology of this structure is tied to some variables, but the most influential is the temperature gradient as a function of time and distance along the freezing direction. Freeze-casts have at least three apparent morphological regions. At the side where freezing initiates is a nearly isotropic region with no visible macropores dubbed the Initial Zone (IZ). Directly after the IZ is the Transition Zone (TZ), where macropores begin to form and align with one another. The pores in this region may appear randomly oriented. The third zone is called the Steady-State Zone (SSZ), macropores in this region are aligned with one another and grow in a regular fashion. Within the SSZ, the structure is defined by a value λ that is the average thickness of a ceramic wall and its adjacent macropore. Although the ability of ice to exclude suspended particles has long been known, the mechanism is still being debated. It was believed initially that during the moments immediately following the nucleation of the ice crystals, particles were ejected from the growing planar ice front, leading to the formation of a constitutionally super-cooled zone directly ahead of the growing ice | https://en.wikipedia.org/wiki?curid=39211211 |
Freeze-casting This unstable region eventually resulted in perturbations, breaking the planar front into a columnar ice front, a phenomenon better known as a Mullins-Serkerka instability. After the breakdown, the ice crystals grow along the temperature gradient, pushing ceramic particles from the liquid phase aside so that they accumulate between the growing ice crystals. However, recent in-situ X-ray radiography of directionally frozen alumina suspensions reveal a different mechanism. In-situ testing reveals that freeze-casting is an aggressive growth process. In the moments immediately before nucleation, the suspension is in an unstable super-cooled state. Homogeneous (spatially speaking) nucleation of ice crystals occurs followed by explosive crystal growth in every spatial and crystallographic direction. The initial nucleation and growth steps are so rapid (approaching 800 mm s) that all suspended particles are completely engulfed by the oncoming ice front because not enough time is given for particle redistribution, resulting in a structure with anisotropic particle distribution. This step is what provides the initial zone structure. As solidification slows and growth kinetics become rate-limiting, the ice crystals begin to exclude the particles, redistributing them within the suspension. A competitive growth process develops between two crystal populations, those with their basal planes aligned with the thermal gradient (z-crystals) and those that are randomly oriented (r-crystals) giving rise to the start of the TZ | https://en.wikipedia.org/wiki?curid=39211211 |
Freeze-casting There are colonies of similarly aligned ice crystals growing throughout the suspension. There are fine lamellae of aligned z-crystals growing with their basal planes aligned with the thermal gradient. The r-crystals appear in this cross-section as platelets but in actuality, they are most similar to columnar dendritic crystals cut along a bias. Within the transition zone, the r-crystals either stop growing or turn into z-crystals that eventually become the predominant orientation, and lead to steady-state growth. There are some reasons why this occurs. For one, during freezing, the growing crystals tend to align with the temperature gradient, as this is the lowest energy configuration and thermodynamically preferential. Aligned growth, however, can mean two different things. Assuming the temperature gradient is vertical, the growing crystal will either be parallel (z-crystal) or perpendicular (r-crystal) to this gradient. A crystal that lays horizontally can still grow in line with the temperature gradient, but it will mean growing on its face rather than its edge. Since the thermal conductivity of ice is so small (1.6 - 2.4 W mK) compared with most every other ceramic (ex. AlO= 40 W mK), the growing ice will have a significant insulative effect on the localized thermal conditions within the slurry. This can be illustrated using simple resistor elements. When ice crystals are aligned with their basal planes parallel to the temperature gradient (z-crystals), they can be represented as two resistors in parallel | https://en.wikipedia.org/wiki?curid=39211211 |
Freeze-casting The thermal resistance of the ceramic is significantly smaller than that of the ice however, so the apparent resistance can be expressed as the lower R. If the ice crystals are aligned perpendicular to the temperature gradient (r-crystals), they can be approximated as two resistor elements in series. For this case, the R is limiting and will dictate the localized thermal conditions. The lower thermal resistance for the z-crystal case leads to lower temperatures and greater heat flux at the growing crystals tips, driving further growth in this direction while, at the same time, the large R value hinders the growth of the r-crystals. Each ice crystal growing within the slurry will be some combination of these two scenarios. Thermodynamics dictate that all crystals will tend to align with the preferential temperature gradient causing r-crystals to eventually give way to z-crystals, which can be seen from the following radiographs taken within the TZ. When z-crystals become the only significant crystal orientation present, the ice-front grows in a steady-state manner except there are no significant changes to the system conditions. It was observed in 2012 that, in the initial moments of freezing, there are dendritic r-crystals that grow 5 - 15 times faster than the solidifying front. These shoot up into the suspension ahead of the main ice front and partially melt back. These crystals stop growing at the point where the TZ will eventually fully transition to the SSZ | https://en.wikipedia.org/wiki?curid=39211211 |
Freeze-casting Researchers determined that this particular point marks the position where the suspension is in an equilibrium state (i.e. freezing temperature and suspension temperature are equal). We can say then that the size of the initial and transition zones are controlled by the extent of supercooling beyond the already low freezing temperature. If the freeze-casting setup is controlled so that nucleation is favored at only small supercooling, then the TZ will give way to the SSZ sooner. The structure in this final region contains long, aligned lamellae that alternate between ice crystals and ceramic walls. The faster a sample is frozen, the finer its solvent crystals (and its eventual macroporosity) will be. Within the SSZ, the normal speeds which are usable for colloidal templating are 10 – 100 mm s leading to solvent crystals typically between 2 mm and 200 mm. Subsequent sublimation of the ice within the SSZ yields a green ceramic preform with porosity in a nearly exact replica of these ice crystals. The microstructure of a freeze-cast within the SSZ is defined by its wavelength "(λ)" which is the average thickness of a single ceramic wall plus its adjacent macropore. Several publications have reported the effects of solidification kinetics on the microstructures of freeze-cast materials. It has been shown that "λ" follows an empirical power-law relationship with solidification velocity "(υ)" (Eq. 2 | https://en.wikipedia.org/wiki?curid=39211211 |
Freeze-casting 14): formula_4 Both "A" and "υ" are used as fitting parameters as currently there is no way of calculating them from first principles, although it is generally believed that "A" is related to slurry parameters like viscosity and solid loading while "n" is influenced by particle characteristics. There are two general categories of tools for architecture a freeze-cast: Initially, the materials system is chosen based on what sort of final structure is needed. This review has focused on water as the vehicle for freezing, but there are some other solvents that may be used. Notably, camphene, which is an organic solvent that is waxy at room temperature. Freezing of this solution produces highly branched dendritic crystals. Once the materials system is settled on however, the majority of microstructural control comes from external operational conditions such as mold material and temperature gradient. The microstructural wavelength (average pore + wall thickness) can be described as a function of the solidification velocity v (λ= Av) where "A" is dependent on solids loading. There are two ways then that the pore size can be controlled. The first is to change the solidification speed that then alters the microstructural wavelength, or the solids loading can be changed. In doing so, the ratio of pore size to wall size is changed. It is often more prudent to alter the solidification velocity seeing as a minimum solid loading is usually desired | https://en.wikipedia.org/wiki?curid=39211211 |
Freeze-casting Since microstructural size "(λ)" is inversely related to the velocity of the freezing front, faster speeds lead to finer structures, while slower speeds produce a coarse microstructure. Controlling the solidification velocity is, therefore, crucial to being able to control the microstructure. Additives can prove highly useful and versatile in changing the morphology of pores. These work by affecting the growth kinetics and microstructure of the ice in addition to the topology of the ice-water interface. Some additives work by altering the phase diagram of the solvent. For example, water and NaCl have a eutectic phase diagram. When NaCl is added into a freeze-casting suspension, the solid ice phase and liquid regions are separated by a zone where both solids and liquids can coexist. This briny region is removed during sublimation, but its existence has a strong effect on the microstructure of the porous ceramic. Other additives work by either altering the interfacial surface energies between the solid/liquid and particle/liquid, changing the viscosity of the suspension, or the degree of undercooling in the system. Studies have been done with glycerol, sucrose, ethanol, Coca-Cola, acetic acid and more. If a freeze casting setup with a constant temperature on either side of the freezing system is used, (static freeze-casting) the front solidification velocity in the SSZ will decrease over time due to the increasing thermal buffer caused by the growing ice front | https://en.wikipedia.org/wiki?curid=39211211 |
Freeze-casting When this occurs, more time is given for the anisotropic ice crystals to grow perpendicularly to the freezing direction (c-axis) resulting in a structure with ice lamellae that increase in thickness along the length of the sample. To ensure highly anisotropic, yet predictable solidification behavior within the SSZ, dynamic freezing patterns are preferred. Using dynamic freezing, the velocity of the solidification front, and, therefore, the ice crystal size, can be controlled with a changing temperature gradient. The increasing thermal gradient counters the effect of the growing thermal buffer imposed by the growing ice front. It has been shown that a linearly decreasing temperature on one side of a freeze-cast will result in near-constant solidification velocity, yielding ice crystals with an almost constant thickness along the SSZ of an entire sample. However, as pointed out by Waschkies et al. even with constant solidification velocity, the thickness of the ice crystals does increase slightly over the course of freezing. In contrast to that, Flauder et al. demonstrated that an exponential change of the temperature at the cooling plate leads to a constant ice crystal thickness within the complete SSZ, which was attributed to a measurably constant ice-front velocity in a distinct study. This approach enables a prediction of the ice-front velocity from the thermal parameters of the suspension | https://en.wikipedia.org/wiki?curid=39211211 |
Freeze-casting Consequently, if the exact relationship between the pore diameter and ice-front velocity is known, an exact control over the pore diameter can be achieved. Even if the temperature gradient within the slurry is perfectly vertical, it is common to see tilting or curvature of the lamellae as they grow through the suspension. To explain this, it is possible to define two distinct growth directions for each ice crystal. There is the direction determined by the temperature gradient, and the one defined by the preferred growth direction crystallographically speaking. These angles are often at odds with one another, and their balance will describe the tilt of the crystal. The non-overlapping growth directions also help to explain why dendritic textures are often seen in freeze-casts. This texturing is usually found only on the side of each lamella; the direction of the imposed temperature gradient. The ceramic structure left behind shows the negative image of these dendrites. In 2013, Deville et al. made the observation that the periodicity of these dendrites (tip-to-tip distance) actually seems to be related to the primary crystal thickness. Up until now, the focus has been mostly on the structure of the ice itself; the particles are almost an afterthought to the templating process but in fact, the particles can and do play a significant role during freeze-casting. It turns out that particle arrangement also changes as a function of the freezing conditions | https://en.wikipedia.org/wiki?curid=39211211 |
Freeze-casting For example, researchers have shown that freezing velocity has a marked effect on wall roughness. Faster freezing rates produce rougher walls since particles are given insufficient time to rearrange. This could be of use when developing permeable gas transfer membranes where tortuosity and roughness could impede gas flow. It also turns out that z- and r-crystals do not interact with ceramic particles in the same way. The z-crystals pack particles in the x-y plane while r-crystals pack particles primarily in the z-direction. R-crystals actually pack particles more efficiently than z-crystals and because of this, the area fraction of the particle-rich phase (1 - area fraction of ice crystals) changes as the crystal population shifts from a mixture of z- and r-crystals to only z-crystals. Starting from where ice crystals first begin to exclude particles, marking the beginning of the transition zone, we have a majority of r-crystals and a high value for the particle-rich phase fraction. We can assume that because the solidification speed is still rapid that the particles will not be packed efficiently. As the solidification rate slows down, however, the area fraction of the particle-rich phase drops indicating an increase in packing efficiency. At the same time, the competitive growth process is taking place, replacing r-crystals with z-crystals | https://en.wikipedia.org/wiki?curid=39211211 |
Freeze-casting At a certain point nearing the end of the transition zone, the particle-rich phase fraction rises sharply since z-crystals are less efficient at packing particles than r-crystals. The apex of this curve marks the point where only z-crystals are present (SSZ). During steady-state growth, after the maximum particle-rich phase fraction is reached, the efficiency of packing increases as steady-state is achieved. In 2011, researchers at Yale University set out to probe the actual spatial packing of particles within the walls. Using small-angle X-ray scattering (SAXS) they characterized the particle size, shape and interparticle spacing of nominally 32 nm silica suspensions that had been freeze-cast at different speeds. Computer simulations indicated that for this system, the particles within the walls should not be touching but rather separated from one another by thin films of ice. Testing, however, revealed that the particles were, in fact, touching and more than that, they attained a packed morphology that cannot be explained by typical equilibrium densification processes. In an ideal world, the spatial concentration of particles within the SSZ would remain constant throughout solidification. As it happens, though, the concentration of particles does change during compression, and this process is highly sensitive to solidification speed. At low freezing rates, Brownian motion takes place, allowing particles to move easily away from the solid-liquid interface and maintain a homogeneous suspension | https://en.wikipedia.org/wiki?curid=39211211 |
Freeze-casting In this situation, the suspension is always warmer than the solidified portion. At fast solidification speeds, approaching VC, the concentration, and concentration gradient at the solid-liquid interface increases because particles cannot redistribute soon enough. When it has built up enough, the freezing point of the suspension is below the temperature gradient in the solution and morphological instabilities can occur. For situations where the particle concentration bleeds into the diffusion layer, both the actual and freezing temperature dip below the equilibrium freezing temperature creating an unstable system. Often, these situations lead to the formation of what are known as ice lenses. These morphological instabilities can trap particles, preventing full redistribution and resulting in inhomogeneous distribution of solids along the freezing direction as well as discontinuities in the ceramic walls, creating voids larger than intrinsic pores within the walls of the porous ceramic. can be applied to numerous materials systems including ceramics, polymers, and metals. As long as there are particles that may be excluded when the solvent changes phase, a templated structure is possible. Using various novel processing techniques, some authors have demonstrated even greater levels of control made available with freeze-casting. Munch et al. showed that it is possible to control the long-range arrangement and orientation of crystals normal to the growth direction by templating the nucleation surface | https://en.wikipedia.org/wiki?curid=39211211 |
Freeze-casting This technique works by providing lower energy nucleation sites to control the initial crystal growth and arrangement. The orientation of ice crystals can also be affected by applied electromagnetic fields as was demonstrated in 2010 by Tang et al. Using specialized setups, researchers have been able to create radially aligned freeze-casts tailored for filtration or gas separation applications. Inspired by Nature, scientists have also been able to use coordinating chemicals and cryopreserved to create remarkably distinctive microstructural architectures | https://en.wikipedia.org/wiki?curid=39211211 |
ISASMELT The process is an energy-efficient smelting process that was jointly developed from the 1970s to the 1990s by Mount Isa Mines Limited (a subsidiary of MIM Holdings Limited and now part of Glencore plc) and the Australian government’s Commonwealth Scientific and Industrial Research Organisation ("CSIRO"). It has relatively low capital and operating costs for a smelting process. technology has been applied to lead, copper, and nickel smelting, and by 2013 fifteen plants were in operation in ten countries, with another five in various stages of development. The installed capacity of the operating plants in 2013 was over 8 million tonnes per year (t/y) of feed materials, with additional capacity to come on line in 2013 and 2014. Smelters based on the copper process are among the lowest-cost copper smelters in the world. An furnace is an upright-cylindrical shaped steel vessel that is lined with refractory bricks. There is a molten bath of slag, matte or metal (depending on the application) at the bottom of the furnace. A steel lance is lowered into the bath through a hole in the roof of the furnace, and air or oxygen-enriched air that is injected through the lance into the bath causes vigorous agitation of the bath. Mineral concentrates or materials for recycling are dropped into the bath through another hole in the furnace roof or, in some cases, injected down the lance | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT These feed materials react with the oxygen in the injected gas, resulting in an intensive reaction in a small volume (relative to other smelting technologies). lances contain one or more devices called "swirlers" that cause the injected gas to spin within the lance, forcing it against the lance wall, cooling it. The swirler consists of curved vanes around a central pipe forming an annular flow. They are designed to minimize pressure losses changing the angle from axial to tangential thus creating a strong vortex . The vortex helps mix liquids and solids with oxygen in the bath. The cooling effect results in a layer of slag "freezing" on the outside of the lance. This layer of solid slag protects the lance from the high temperatures inside the furnace. The tip of the lance that is submerged in the bath eventually wears out, and the worn lance is easily replaced with a new one when necessary. The worn tips are subsequently cut off and a new tip welded onto the lance body before it is returned to the furnace. furnaces typically operate in the range of 1000–1200 °C, depending on the application. The refractory bricks that form the internal lining of the furnace protect the steel shell from the heat inside the furnace. The products are removed from the furnace through one or more "tap holes" in a process called "tapping" | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT This can be either continuous removal or in batches, with the tap holes being blocked with clay at the end of a tap, and then reopened by drilling or with a thermic lance when it is time for the next tap. The products are allowed to separate in a settling vessel, such as a rotary holding furnace or an electric furnace. While smelting sulfide concentrates, most of the energy needed to heat and melt the feed materials is derived from the reaction of oxygen with the sulfur and iron in the concentrate. However, a small amount of supplemental energy is required. furnaces can use a variety of fuels, including coal, coke, petroleum coke, oil and natural gas. The solid fuel can be added through the top of the furnace with the other feed materials, or it can be injected down the lance. Liquid and gaseous fuels are injected down the lance. The advantages of the process include: The history of the process began with the invention in 1973 of the Sirosmelt lance by Drs Bill Denholm and John Floyd at the CSIRO. The lance was developed as a result of investigations into improved tin-smelting processes, in which it was found that the use of a top-entry submerged lance would result in greater heat transfer and mass transfer efficiencies. The idea of top-entry submerged lances goes back to at least 1902, when such a system was attempted in Clichy, France. However, early attempts failed because of the short lives of the lances on submersion in the bath | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT The Mitsubishi copper smelting process is one alternative approach, wherein lances are used in a furnace, but they are not submerged into the bath. Instead, they blow oxygen-enriched air onto the surface of the slag (top jetting). Similarly, a water-cooled, top-jetting lance was the basis of the LD (Linz-Donawitz) steelmaking process. This does not produce the same intensity of mixing in the bath as a submerged lance. The CSIRO scientists first tried developing a submerged lance system using a water-cooled lance system, but moved to an air-cooled system because "scale up of the water-cooled lance would have been problematic". Introducing any water to a system involving molten metals and slags can result in catastrophic explosions, such as that in the Scunthorpe Steelworks in November 1975 in which 11 men lost their lives. The inclusion of the swirlers in the Sirosmelt lance and forming a splash coating of slag on the lance were the major innovations that led to the successful development of submerged lance smelting | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT From 1973, the CSIRO scientists began a series of trials using the Sirosmelt lance to recover metals from industrial slags in Australia, including lead softener slag at the Broken Hill Associated Smelters in Port Pirie (1973), tin slag from Associated Tin Smelters in Sydney (1974), copper converter slag at the Electrolytic Refining and Smelting ("ER&S") Port Kembla plant (1975) and copper anode furnace slag at Copper Refineries Limited (another subsidiary of MIM Holdings) in Townsville (1976) and of copper converter slag in Mount Isa (1977). The work then proceeded to smelting tin concentrates (1975) and then sulfidic tin concentrates (1977). MIM and ER&S jointly funded the 1975 Port Kembla converter slag treatment trials and MIM’s involvement continued with the slag treatment work in Townsville and Mount Isa. In parallel with the copper slag treatment work, the CSIRO was continuing to work in tin smelting. Projects included a five tonne ("t") plant for recovering tin from slag being installed at Associated Tin Smelters in 1978, and the first sulfidic smelting test work being done in collaboration with Aberfoyle Limited, in which tin was fumed from pyritic tin ore and from mixed tin and copper concentrates. Aberfoyle was investigating the possibility of using the Sirosmelt lance approach to improve the recovery of tin from complex ores, such as its mine at Cleveland, Tasmania, and the Queen Hill ore zone near Zeehan in Tasmania | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT The Aberfoyle work led to the construction and operation in late 1980 of a four t/h tin matte fuming pilot plant at the Western Mining Corporation’s Kalgoorlie Nickel Smelter, located to the south of Kalgoorlie, Western Australia. In the early 1970s, the traditional blast furnace and sinter plant technology that was the mainstay of the lead smelting industry was coming under sustained pressure from more stringent environmental requirements, increased energy costs, decreasing metal prices and rising capital and operating costs. Many smelting companies were seeking new processes to replace sinter plants and blast furnaces. Possibilities included the QSL lead smelting process, the Kivcet process, the Kaldo top-blown rotary converter, and adapting Outokumpu’s successful copper and nickel flash furnace to lead smelting. MIM was seeking ways to safeguard the future of its Mount Isa lead smelting operations. It did this in two ways: MIM investigated new technologies by arranging plant testing of large parcels of Mount Isa lead concentrates for all the then process options except for the Kivcet process. At the same time, it had been aware of the use of top-jetting lances in the Mitsubishi and Kaldo processes, and of top-entry submerged combustion lance investigations undertaken by ASARCO Limited (which had a long association with MIM, including being a shareholder in MIM Holdings) in the 1960s. This stimulated MIM’s interest in the Sirosmelt lance, which was seen as a way to produce a robust submerged lance | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT Following the copper slag trials of 1976–1978, MIM initiated a joint project with the CSIRO in 1978 to investigate the possibility of applying Sirosmelt lances to lead smelting. The work began with computer modelling the equilibrium thermodynamics (1978) and was followed by laboratory bench-scale test work using large alumina silicate crucibles (1978–1979). The results were sufficiently encouraging that MIM built a 120 kg/h test rig in Mount Isa. It began operation in September 1980. This was used to develop a two-stage process to produce lead bullion from Mount Isa lead concentrate. The first stage was an oxidation step that removed virtually all the sulfur from the feed, oxidising the contained lead to lead oxide (PbO) that was largely collected in the slag (some was carried out of the furnace as lead oxide fume that was returned for lead recovery). The second stage was a reduction step in which the oxygen was removed from the lead to form lead metal. Following the 120 kg/h test work, MIM decided to proceed to install a 5 t/h lead pilot plant in its Mount Isa lead smelter. It bought Aberfoyle’s matte fuming furnace and transported it from Kalgoorlie to Mount Isa, where it was rebuilt and commissioned in 1983 to demonstrate the first stage of the process in continuous operation and for testing the reduction step using batches of high-lead slag. One of the key features of the pilot plant was that it was run by operations’ personnel in the lead smelter as though it was an operations’ plant | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT The high lead slag produced by the continuous smelting of the lead concentrate was subsequently treated in the sinter plant, thus increasing the production of the lead smelter by up to 17%. This gave the operations’ people ownership of the plant and an incentive to make it work, thus ensuring management and maintenance priority. It also gave MIM assurance that the process simple enough to be operable in a production environment, with normal staff and supervision, and that it was robust enough to withstand normal control excursions. In addition to the continuous operation of lead concentrate to produce high-lead slag, the pilot plant was used to produce lead metal from batches of the slag, investigate the wear rates of the furnace’s refractory lining and lances, and initial work aimed at developing a low-pressure version of the Sirosmelt lance. The result was a lance design that allowed operation at significantly lower pressure than the initial values of about 250 kilopascal (gauge) ("kPag"), thus reducing operating costs. MIM built a second, identical furnace next to the first, and commissioned it in August 1985. This combination of furnaces was used to demonstrate the two-stage process in continuous operation in mid-1987. However, for most of the time the two furnaces were not able to operate simultaneously due to a constraint in the capacity of the baghouse used to filter the lead dust from the waste gas | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT A series of process improvements, particularly in the waste gas handling system, resulted in increasing the throughput of the plant from the initial design of 5 t/h to 10 t/h. The pilot plant had treated more than 125,000 t of lead concentrate by April 1989. The two furnaces were also used to develop a process to recover lead from the Mount Isa lead smelter’s drossing operations. Based on the results of the pilot plant work, the MIM Holdings Board of Directors approved the construction of an A$65 million demonstration plant, capable of producing 60,000 t/y of lead bullion. This plant operated from early 1991 until 1995. It was initially designed to treat 20 t/h of lead concentrate using lance air enriched to 27%. However, the oxygen originally designated for its use was diverted to the more profitable copper smelting operations, and the feed rate to the lead demonstration plant was severely restricted. When there was sufficient oxygen available in 1993 to increase the enrichment level to 33–35%, treatment rates of up to 36 t/h of concentrate were achieved, with residual lead in the final reduction furnace slag being in the range of 2–5%. The two-stage approach to lead smelting was partly driven by the relatively low lead content of Mount Isa lead concentrates (typically in the range of 47–52% lead during the lead development period) | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT Trying to produce lead bullion in a single furnace with such low concentrate grades would result in excessive fuming of lead oxide with a huge amount of material that would have to be returned to the furnace to recover the lead and, consequently, a higher energy demand as that material had to be reheated to the furnace temperatures. Concentrates with higher lead contents can be smelted directly into lead metal in a single furnace without excess fuming. This was demonstrated on the large scale in 1994, when 4000 t of concentrate containing 67% lead were treated at rates up to 32 t/h with lance air enriched to 27%. During these trials, 50% of the lead in the concentrate was converted to lead bullion in the smelting furnace, while most of the rest ended up as lead oxide in the smelting furnace slag. Like the lead pilot plant, the lead demonstration plant suffered from constraints imposed by the waste gas handling system. In the case of the demonstration plant, the problem was caused by sticky fume that formed an insulating layer on the convection tube bundles of the waste heat boilers, significantly reducing the heat transfer rates and thus the ability of the boilers to reduce the waste gas temperature. As the plant used baghouses to filter lead fume from the waste gas, it was necessary to reduce the temperature of the gas below the point at which the bags would be damaged by high temperatures | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT The problem was solved by allowing cool air to mix with the hot waste gas to lower the temperature to a level at which the baghouse could operate. This reduced the plant’s capacity because it was again limited by the volume of gas that could be filtered by the baghouse. The lead demonstration plant was mothballed in 1995 because there was insufficient concentrate to keep both it and the rest of the lead smelter operating. It was too small to treat all the Mount Isa lead concentrate by itself. The first commercial primary-lead furnace was installed at the Yunnan Chihong Zinc and Germanium Company Limited (YCZG) greenfield zinc and lead smelting complex at Qujing in Yunnan Province in China. This furnace was part of a plant consisting of the furnace and a blast furnace specially designed to treat high-lead slag. The furnace was designed to produce both the slag and lead bullion, with about 40% of the lead in the concentrate being converted to lead bullion in the furnace. The ISASMELT–blast furnace combination was designed to treat 160,000 t/y of lead concentrate. The second commercial primary-lead furnace was commissioned at Kazzinc’s smelting complex at Ust-Kamenogorsk in Kazakhstan in 2012. It is designed to treat 300,000 t/y of lead concentrate, again using an ISASMELT–blast furnace combination. YCZG is constructing another lead at a new greenfield smelter in Huize in China, and this is due to be commissioned in 2013 | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT In June 2017, Glencore announced that Nyrstar NV had acquired an Isasmelt licence for its new Ausmelt furnace in Port Pirie. As part of the agreement, Nyrstar engaged training and ramp-up support services for the Ausmelt furnace and blast furnace by personnel from Glencore's Kazzinc operations in Kazakhstan. This involved training Nyrstar personnel at Ust-Kamenogorsk operations and site support by Kazzinc personnel during the commissioning and ramp-up stages of the Ausmelt plant. While the lead 5 t/h pilot plant was being designed in 1982–1983, MIM continued to use the 120 kg/h test rig to develop other processes, including the dross treatment process previously mentioned, and the treatment of lead-acid battery paste for lead recycling. The MIM Holdings Board of Directors approved the construction of an plant at Britannia Refined Metals, the company’s lead refinery at Northfleet in the United Kingdom, for commercial recovery of lead from battery paste to supplement the existing plant, which used a short rotary furnace to produce 10,000 t/y of lead. The new plant increased annual production to 30,000 t/y of recycled lead, and was commissioned in 1991. The furnace was used to produce low-antimony lead bullion from the battery paste and an antimony-rich slag that contained 55–65% lead oxide | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT While it was possible to recover the lead from the slag in the furnace by a reduction step, the total throughput of the plant was increased by treating the slag in the short rotary furnace when sufficient quantities of the slag had been generated. The plant was designed to treat 7.7 t/h of battery paste, but routinely treated 12 t/h. The plant was shut down in 2004 when Xstrata Zinc, which took over the MIM Holdings lead operations, decided to leave the lead recycling business. A second lead plant for recovering lead from recycled batteries was commissioned in 2000 in Malaysia at Metal Reclamation Industries’ Pulau Indah plant. This plant has a design capacity of 40,000 t/y of lead bullion. Scientists at the CSIRO conducted small-scale test work on copper sulfide concentrate in 1979, using the CSIRO’s 50 kg Sirosmelt test rig. These trials included producing copper matte containing 40–52% copper and, in some cases, converting the matte to produce blister copper. The results of this work were sufficiently encouraging that MIM in 1983 undertook its own copper smelting test work program using its 120 kg/h test rig, which had by then been rerated to 250 kg/h. It was found that the process was easy to control and that copper loss to slag was low. It was also learned that the process could easily recover copper from copper converter slag concentrate, of which there was a large stockpile at Mount Isa. Construction of a 15 t/h demonstration copper plant began in 1986 | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT The design was based on MIM’s 250 kg/h test work and operating experience with the lead pilot plant. It cost A$11 million and was commissioned in April 1987. The initial capital cost was recovered in the first 14 months of operation. As with the lead pilot plant, the copper demonstration plant was integrated into copper smelter operations and justified by the 20% (30,000 t/y) increase in copper production that it provided. It quickly treated the entire backlog of converter slag concentrate, which could not be treated at high rates in the reverberatory furnaces without generating magnetite ("FeO") accretions that would necessitate shutting down the reverberatory furnaces for their removal. The demonstration copper plant was used to further develop the copper process. Refractory life was initially shorter than expected and considerable effort was devoted to understanding the reasons and attempting to extend the life of the refractories. At the end of the life of the demonstration plant, the longest refractory life achieved was 90 weeks. Lance life was also low initially. Inexperienced operators could destroy a lance in as little as 10 minutes. However, as a result of modifications to the lance design, the development of techniques to determine the position of the lance in the bath, and a rise in the operating experience, the typically lance life was extended to a week. The demonstration plant was commissioned with high-pressure (700 kPag) air injected down the lance | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT Later, after extensive testing of low-pressure lance designs and trials using oxygen enrichment of the lance air, a 70 t/d oxygen plant and a 5 Nm3/s blower with a discharge pressure of 146 kPag were purchased. The new lance design was capable of operating at pressures below 100 kPag. Using enrichment of the oxygen in the lance air to 35%, the demonstration plant throughput was lifted to 48 t/h of concentrate, and the gross energy used during smelting was reduced from 25.6 GJ/t of contained copper to 4.1 GJ/t. The successful operation and development of the demonstration copper ISASMELT, and the degree of interest shown in the new process by the global smelting community, gave MIM Holdings sufficient confidence to license the technology to external companies, so an agreement under which MIM could incorporate the Sirosmelt lance into technology was signed with the CSIRO in 1989. MIM signed the first licence agreement with Agip Australia Proprietary Limited ("Agip") in July 1990. Agip, a subsidiary of the Italian oil company ENI, was developing the Radio Hill nickel-copper deposit near Karratha in Western Australia. MIM and representatives of Agip conducted a series of trials in which 4 tonnes of Radio Hill concentrate was smelted in the 250 kg/h test rig at Mount Isa. The Agip plant was designed to treat 7.5 t/h of the Radio Hill concentrate and produce 1.5 t/h of granulated matte with a combined nickel and copper content of 45% for sale., It was the same size as the copper demonstration plant (2 | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT 3 m internal diameter) and had a 5.5 Nm3/s blower to provide the lance air. Commissioning of the plant began in September 1991; however, the Radio Hill mine and smelter complex were forced to close by low nickel prices after less than six months, before commissioning was completed. The furnace achieved its design capacity within three months. Subsequent owners of the mine focussed on mining and mineral processing only, and the plant has been dismantled. In 1973, the Freeport-McMoRan Copper and Gold Inc. ("Freeport") smelter at Miami, Arizona, installed a 51 MW electric furnace at its Miami smelter. The decision was based on a long-term electrical power contract with the Salt River Project that provided the company with a very low rate for electricity. This contract expired in 1990 and the resulting increase in electricity prices prompted the then owners of the smelter, Cyprus Miami Mining Corporation ("Cyprus"), to seek alternative smelting technologies to provide lower operating costs. The technologies evaluated included the: The Contop, Inco, Mitsubishi and Outokumpu processes "were all eliminated primarily because of their high dust levels, high capital costs and poor adaptability to the existing facility". The Teniente converter was ruled out because it required the use of the electric furnace for partial smelting. The Noranda reactor was not selected "because of its high refractory wear and its poor adaptability to the existing plant due to the handling of the reactor slag" | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT was chosen as the preferred technology and a licence agreement was signed with MIM in October 1990. The major factor in the decision to select the technology was the ability to fit it into the existing plant and to maximise the use of existing equipment and infrastructure, while the major disadvantage was seen to be the risks associated with scaling up the technology from the Mount Isa demonstration plant. The Miami copper furnace was designed to treat 590,000 t/y (650,000 short tons per year) of copper concentrate, a treatment rate that was constrained by the capacity of the sulfuric acid plant used to capture the sulfur dioxide from the smelter’s waste gases. The existing electric furnace was converted from smelting duties to a slag cleaning furnace and providing matte surge capacity for the converters. The furnace was commissioned on 11 June 1992 and in 2002 treated over 700,000 t/y of concentrate. The modernisation of the Miami smelter cost an estimated US$95 million. In 1993, the Cyprus Minerals Company merged with AMAX to form the Cyprus Amax Minerals company, which was in turn taken over by the Phelps Dodge Corporation in late 1999. Phelps Dodge was acquired by Freeport in 2006. The Miami smelter is one of only three remaining operating copper smelters in the United States, where there were 16 in 1979. The third commercial copper plant was installed in MIM’s Mount Isa copper smelter at a cost of approximately A$100 million | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT It was designed to treat 104 t/h of copper concentrate, containing 180,000 t/y of copper, and it began operation in August 1992. A significant difference between the Mount Isa copper plant and all the others is that it uses an Ahlstrom Fluxflow waste heat boiler to recover heat from the furnace waste gas. This boiler uses a recirculating fluid bed of particles to rapidly quench the gas as it leaves the furnace, and then uses the enhanced heat transfer properties of solid–solid contact to cool the particles as they are carried past boiler tubes that are suspended in a shaft above the bed. The high heat transfer rate means that the Fluxflow boiler is relatively compact compared with conventional waste heat boilers and the rapid cooling of the waste gas limits the formation of sulfur trioxide ("SO"), which in the presence of water forms sulfuric acid that can cause corrosion of cool surfaces. In the early years of operation, the Fluxflow boiler was the cause of significant down time, because the rate of wear of the boiler tubes was much higher than expected. The problems were solved by understanding the gas flows within the boiler redesigning the boiler tubes to minimise the effects of erosion. The life of the refractory bricks in the furnace was initially shorter than expected and a water cooling system was briefly considered to extend them; however, this was not installed and operational improvements have resulted in a significant extension of the life of the lining without this capital and operating expense | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT Since 1998, the refractory lining lives have exceeded the two-year design life, with lives of the 8th and 9th linings almost reaching three years. The most recent lining lasted for 50 months, with the one before that lasting for 44 months. In the first years of operation at Mount Isa, the throughput of the furnace was constrained by problems with some of the ancillary equipment in the plant, including the boiler, slag granulation system and concentrate filters. The ultimate constraint was the decision during its construction to keep one of the two reverberatory furnaces on line to increase the copper smelter production to 265,000 t/y of anode copper. The smelter’s Peirce-Smith converters became a bottleneck and the feed rate of the furnace had to be restrained to allow sufficient matte to be drawn from the reverberatory furnace to prevent it freezing solid. The 12-month rolling average of the feed rate fell just short of 100 t/h for much of this period, not quite reaching the design annual average of 104 t/h. MIM decided to shut down the reverberatory furnace in 1997, and the plant 12-month rolling mean feed rate quickly exceeded the 104 t/h design when this constraint was lifted. The performance of the plant was sufficiently encouraging that MIM decided to expand the treatment rate to 166 t/h by adding a second oxygen plant to allow higher enrichment of the lance air | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT As a result, by late 2001 it had achieve a peak rate of 190 t/h of concentrate, and the smelter produced a peak annual total of 240,000 t of anode copper. At that time, the Mount Isa copper smelter, together with its copper refinery in Townsville, was among the lowest cost copper smelters in the world. Lance life is typically two weeks, with lance changes taking 30 to 40 minutes, and repairs usually being limited to replacement of the lance tips. In 2006, MIM commissioned a second rotary holding furnace that operates in parallel with the existing holding furnace. Sterlite Industries ("Sterlite"), now a subsidiary of Vedanta Resources plc ("Vedanta"), built a copper smelter in Tuticorin using an furnace and Peirce-Smith converters. The smelter was commissioned in 1996 and was designed to produce 60,000 t/y of copper (450,000 t/y of copper concentrate), but by increasing the oxygen content of the lance air and making modifications to other equipment, the furnace feed rate was increased to the point where the smelter was producing 180,000 t/y of copper. Sterlite commissioned a new furnace in May 2005 that was designed to treat 1.3 million t/y of copper concentrate, and the smelter’s production capacity was expanded to 300,000 t/y of copper. The new plant reached its design capacity, measured over a three-month period, six months after it started treating its first feed. Vedanta’s website states that the new furnace was successfully ramped up "in a record period of 45 days" | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT Since then Sterlite has decided to further expand its copper production by installing a third smelter and new refinery using IsaKidd technology. The new smelter will have a design capacity of 1.36 million t/y of copper concentrate (containing 400,000 t/y of copper), processed through a single furnace. In the 1990s, the Chinese government decided to increase the efficiency of the Chinese economy and reduce the environmental effects of heavy industry by modernising plants. As a response, the Yunnan Copper Corporation Limited ("YCC") upgraded its existing plant, which was based on a sinter plant and an electric furnace, with a copper furnace. As with the Miami smelter, the electric furnace was converted from smelting duty to separation of matte and slag and providing matte surge capacity for the converters, and again, the small footprint of the furnace was very important in retrofitting it to the existing smelter. The YCC plant had a design capacity of 600,000 dry t/y of copper concentrate and started smelting concentrate on 15 May 2002. YCC placed a lot of emphasis on training its operators, sending people to Mount Isa for training over a seven-month period during 2001 ahead of the commissioning. The total cost of the smelter modernisation program, including the furnace, was 640 million yuan (approximately US$80 million) and the smelter’s concentrate treatment rate increased from 470,000 t/y to 800,000 t/y as a result | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT The transfer of operating knowledge from MIM to YCC was sufficient for the first furnace refractory lining to last for two years, a marked improvement on the life of the initial lining of other plants. YCC described the modernisation project as "a great success, achieving all that was expected." Energy consumption per tonne of blister copper produced decreased by 34% as a result of installing the furnace, and YCC estimated that during the first 38 months of operation, it saved approximately US$31.4 million through reduced energy costs alone, giving the modernisation a very short payback by industry standards. In 2004, YCC’s management was presented with awards for Innovation in Project Management and the National Medal for High Quality Projects by the Chinese government to mark the success of the smelter modernisation project. Xstrata subsequently licensed YCC to build three more plants, one in Chuxiong in Yunnan Province, China to treat 500,000 t/y of copper concentrate, one in Liangshan in Sichuan Province, China and the other in Chambishi in Zambia to treat 350,000 t/y of concentrate. Chuxiong and Chambishi were commissioned in 2009. Liangshan was commissioned in 2012. Mopani Copper Mines ("Mopani") was part of Zambia Consolidated Copper Mines Limited until it was privatised in 2000. It owns the Mufulira smelter, which operated with an electric furnace with a nominal capacity of 420,000 t/y of copper concentrate (180,000 t/y of new copper) | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT Mopani decided to install a copper plant that could treat 850,000 t/y of copper concentrate, including a purpose-designed electric matte settling furnace to separate the matte and slag and also return slag from the smelter’s Peirce-Smith converters. Before committing to the technology, Mopani considered the following process options: Mopani considered electric furnaces unproven at the proposed concentrate feed rates, and the low sulfur dioxide concentration in the waste gas would make its capture very expensive. Flash furnaces and the Mitsubishi process were excluded because: Mopani excluded the Teniente converter and Noranda reactor because of the poor performance of the Teniente converter at the other Zambian smelter operating at the time and because of "the relatively inexperienced technical resources available at the time". Mopani selected technology over Ausmelt technology after visits to operating plants in Australia, the United States of America, and China. The total cost of the project was US$213 million. The first feed was smelted in September 2006. The Southern Peru Copper Corporation ("SPCC") is a subsidiary of the Southern Copper Corporation ("SCC"), one of the world’s largest copper companies and currently 75.1% owned by Grupo México. Grupo México acquired the shares in SPCC when it bought ASARCO in November 1999 In the 1990s, SPCC was seeking to modernise its smelter at Ilo in southern Peru as part of 1997 commitment to the Peruvian government to capture at least 91 | https://en.wikipedia.org/wiki?curid=39223191 |
ISASMELT 7% of the sulfur dioxide generated in its smelting operations by January 2007. It initially selected flash smelting technology to replace its reverberatory furnaces, at a cost of almost US$1 billion; however, one of the first actions following Grupo México’s acquisition of ASARCO was to review the proposed Ilo smelter modernisation plans. Six different technologies were evaluated during the review. These were: The technology was selected as a result of the review, resulting in a reduction in the capital cost of almost 50% and was also the alternative with the lowest operating costs. The plant was commissioned in February 2007. In June 2009, the plant had an average feed rate of 165.2 t/h of concentrate and 6.3 t/h of reverts (cold copper-bearing materials that arise from spillage and accretions in the pots used to transport matte or other molten materials). SPCC has reported a cost of approximately $600 million for the smelter modernization. Kazzinc selected the copper process for its Ust-Kamenogorsk metallurgical complex. It is designed to treat 290,000 t/y of copper concentrate and was commissioned in 2011. A projected capital cost for the smelter and refinery in 2006 was US$178 million. In the fourth quarter of 2011, the First Quantum Minerals board approved the construction of an ISASMELT-based smelter at Kansanshi in Zambia. The smelter is to process 1.2 million t/y of copper concentrate to produce over 300,000 t/y of copper and 1.1 million t/y of sulfuric acid as a by-product | https://en.wikipedia.org/wiki?curid=39223191 |
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