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2003-04-01 | The Cu(I)-phenolate complexes ^1LCu and ^2LCu and the Cu(I)-phenol complex [H^2LCu(CNC_6H_3Me_2)]BArF_4 were prepared and structurally characterized by X-ray crystallography, where ^1L^− and ^2L^− are ligands comprised of a 2,4-di- tert -butylphenolate linked to 1-isopropyl-1,5-diazacyclooctane or 1,4-diisopropyl-1,4,7-triazacyclononane, respectively. The reduced galactose oxidase (GAO) structural models ^1LCu and ^2LCu were found to be highly reactive with O_2, and through combined stopped-flow kinetic and EPR, UV-vis, and resonance Raman spectroscopic studies of the oxygenation of ^2LCu at low temperature, new intermediates relevant to those postulated for the active site oxidation step of the GAO catalytic cycle were identified. The oxygenation was shown by kinetics experiments to proceed via initial binding of O_2 to yield a green, unusually thermodynamically stable 1:1 adduct, ^2LCu(O_2). Symmetric (η^2) binding of a superoxo ligand was indicated by oxygen-isotope-sensitive features in resonance Raman spectra obtained in batch experiments; peaks at ν(^16O_2)=1120 cm^−1, ν(^18O^16O)=1093 cm^−1, and ν(^18O_2)=1058 cm^−1 were assigned as O-O stretching vibrations. These data represent the first experimental evidence for such superoxide coordination in complexes of tetradentate tripodal ligands and provide new precedent for how O_2 may bind at the reduced GAO active site. The 1:1 Cu/O_2 adduct subsequently evolves into a metastable purple species that is only observable under conditions of substoichiometric O_2. The kinetics of formation of this transient species are second order overall (rate= k′ _2[^2LCu(O_2)][^2LCu]). It exhibits an absorption band with λ_max=565 nm (ε=17,900 M^−1 cm^−1) and multiple oxygen-isotope-sensitive ν(Cu-O) and ν(O-O) features in the respective regions 500–550 cm^−1 and 700–850 cm^−1 in Raman spectra, with excitation-wavelength-dependent intensities that correlate with the 565 nm absorption feature. On the basis of the combined data available, the presence of multiple isomeric peroxodicopper species in the transient purple solution is postulated. | Copper(I)-phenolate complexes as models of the reduced active site of galactose oxidase: synthesis, characterization, and O_2 reactivity | 10.1007/s00775-002-0420-9 |
2003-04-01 | The direct determination of element signatures in polar ice core samples from Greenland by laser ablation with subsequent inductively coupled plasma mass spectrometry analysis has been investigated. A cryogenic sample chamber enables the element determination in ice directly from the solid (frozen) state. A procedure was developed to analyse up to 38 elements (traces: Mg, Al, Fe, Zn, Cd, Pb and rare earth elements; minor constituents: Na) in ice samples from Greenland with a previously unachievable spatial resolution of 4 mm along the core axis. This resolution is helpful to detect seasonal variations of element concentration in thin annual layers of deep ice. We report operating conditions and analytical performance of the experimental set up, the improvement of signal stability by ^17OH internal standardisation and application of a desolvation unit. Calibration of the system was performed with frozen multielement standard solutions along a special preparation procedure. Detection limits for the tracers Na, Mg (sea salt), Al (mineral dust) and Zn (anthropogenic source) are 0.1–1 µg kg^−1. Best detection limits in the range of 0.001–0.01 µg kg^−1 were reached for Co, Pb and all rare earth elements. To validate the method, frozen standard reference materials were measured. The recovery is about ±10%. Greenland ice core samples from different ages were analysed with the new technique. The results obtained by laser ablation were compared with values from solution analysis, available published data and the particle content. Most elements have shown good correlation with the particle content in the Greenland samples; however, differences could be seen between the values obtained by laser ablation and solution bulk analysis after a tri-acid digestion. The influence of particles is discussed. The high spatially resolved 2D mapping of element concentrations shows strong inhomogeneities along the core axis most probably due to seasonal variations of element deposition. | Application of LA–ICP–MS in polar ice core studies | 10.1007/s00216-003-1793-5 |
2003-03-01 | The viability of 250 basidiomycete strains was determined after a 2-d and then after a 2-year storage under liquid nitrogen using two different freezing protocols. Using an original agar plug protocol (OP), 162 strains (65%) of the 250 strains survived a 2-d storage and 158 strains (63 %) survived a 2-year storage in liquid nitrogen. Using a straw protocol (CP), 246 strains (98 %) of the 250 strains survived a 2-d storage and 243 strains (97 %) a 2-year storage in liquid nitrogen. In addition, other 106 strains were newly estimated using the CP protocol; 104 (98 %) of them survived successfully a 2-d storage and 101 (95 %) of them survived a 2-year storage in liquid nitrogen. The results indicate that the protocol used for cryopreservation can significantly influence strain survival. Markedly better results were obtained using the CP protocol. | Viability of basidiomycete strains after cryopreservation: Comparison of two different freezing protocols | 10.1007/BF02930959 |
2003-03-01 | The successful separation of 2- and 3-methyl-substituted positional isomers of butanol, butyl acetate, and butanoic acid and its ethyl ester, is reported. These compounds are of interest in the study of wine flavour, however the separation of the 2- and 3-methyl isomers may present problems, and more so in the presence of the wine matrix components, when single capillary column gas chromatography (GC) is used. The strategy to achieve separation was based on the use of shape-selective cyclodextrin derivative (CDD) capillary columns (commonly referred to as chiral columns). These columns provide simultaneous resolution of the enantiomeric pairs of the 2-methyl isomers, and at the same time the ability to separate the 3-methyl isomer from the 2-methyl is achieved in all but the case of the ( S )-2- and 3-methylbutanol. The advantages of using shape-selective columns to perform this study is demonstrated, with coupling of two CDD columns giving improved separations of these compounds. Although these compounds are relatively volatile, cryogenic modulated comprehensive two-dimensional GC was shown to provide good pulsed peak profiles with chiral separation in the first dimension when a thicker film trapping column segment was employed. The components of interest were well separated from other wine matrix components. | Separation of positional isomers by the use of coupled shape-selective stationary phase columns | 10.1007/s00216-003-1768-6 |
2003-01-01 | Comparative Analysis of Versions of Operation of Units for Obtaining Ultrahigh-Purity Cryogenic Products | 10.1023/A:1023706911407 | |
2003-01-01 | The Jet Propulsion Laboratory (JPL) is developing a continuous hydrogen sorption cryocooler for the ESA Planck mission, which will measure the anisotropy in the cosmic microwave background. The sorption cooler is the only active cooling for one of the instruments and it is the first of a chain of three coolers for the other instrument on Planck. The cooler has been designed to provide a cooling capacity of 1.1 W at a temperature below 20 K with a temperature stability requirement of 100 mK over a compressor cycle (667 s). The performance of these coolers depends on many operating parameters (such as the temperatures of pre-cooling thermals shield and the warm radiator and their fluctuations) and compliance can only be assessed through a detailed testing of the whole cooler and its interfaces. A breadboard sorption cooler (EBB) is undergoing testing to verify the flight cooler design performance in terms of input power, cooling power, cold end temperature and cold end temperature fluctuations, heat load on the pre-cooling stages, and heat flow to the warm radiator. We present initial test data compared to predictions based on previously performed component tests. | Initial Test Performance of a Close-Cycle Cotinuos Hydroge Sorption Cooler, the Planck Sorption Breadboard Cooler | 10.1007/0-306-47919-2_84 |
2003-01-01 | LIRIS is a near-infrared (0.9–2.4 microns) intermediate resolution spectrograph (R = 1000 − 4000) with added capabilities for multi-object, imaging, coronography, and polarimetry. This instrument is now being assembled and integrated at the IAC, and upon verification will be installed on the 4.2 m William Herschel Telescope (WHT) at the Observatorio del Roque de Los Muchachos (ORM, La Palma). First commissioning is expected in February 2002 and scientific operations, as a common user instrument, in semester 2003B. | LIRIS a New Near Infrared Spectrograph for the WHT: Project Status | 10.1007/978-94-017-1778-6_95 |
2003-01-01 | An experimental search for ^5H using a secondary beam of ^6He was performed. The transfer reaction p(^6He,^2He)^5H was studied by detecting two protons emitted from the decay of ^2He. A peak consistent with the ^5H resonance at 1.7±0.3 MeV above the n + n + t threshold was observed, with a width of 1.9±0.4 MeV. The angular distribution of the p(^6He,^2He)^5H reaction was measured as well as the energy correlation of two protons. | Superheavy hydrogen ^5H | 10.1007/978-3-642-55560-2_73 |
2003-01-01 | Modern electro-optic applications often contain a cryogenically cooled infrared imager placed upon a stabilized platform which is further connected to an outer housing by low-friction gimbals. Since the active system of gimbal stabilization is dedicated primarily to maintaining the steady line-of-sight control by eliminating the relatively slow effects of yaw, pitch or roll, it may have insufficient resources to suppress an excessive high-frequency vibration exported from the internal active components such as a cryogenic cooler. The vibration protective and thermally conductive interface developed allows the use of the split Stirling cryocooler, relying on highly efficient, cheap and durable linear single-piston compressor within the infrared imager mounted upon the gimbaled stabilized platform. | A Thermally Conductive and Vibration Protective Interface for Linear Cryogenic Coolers in Applications for Gimbaled Infrared Devices | 10.1007/0-306-47919-2_94 |
2003-01-01 | A continuous improvement of Stirling integral coolers MTTF is necessary to answer the new market requirements. The time spent in the design phase is critical to get the product ready at the right time and to reduce the development costs. In order to reduce the development risks (be sure to get in the new design at a higher MTTF), we have developed a calculation method for prediction of the expected MTTF of our coolers. Early in the design phase, we use the method of predictive calculations on MTTF. For that, we need MTTF data for each critical single part or function in the cooler. In order to fill the lack of data available on failure rates for mechanical parts (tightness, coating...) in our particular application, we built a list of the different functions inside the cooler from the failure point of view. The data collected from the extensive lifetest results already performed allow us to determine the MTTF for each function. These elements are introduced into the predictive calculation of the new design. The expected MTTF of the new cooler is then available. The results obtained by calculation are still only indicative. These results have to be verified as quickly as possible. To reduce the duration of lifetests, we apply an accelerated test procedure developed and verified over 2 years. This method allows us to obtain results on MTTF equivalent to several thousand hours using only a test duration of a few weeks. This method has been validated on previous cooler models. This MTTF calculation is today applied to all designs of our integral coolers, and in particular, to our new design of the RM2 cooler under development at Thales Cryogenics. This method will be discussed and the results of the calculations performed on the new RM2 design will be presented. | MTTF Prediction in Design Phase on Thales Cryogenics Integral Coolers | 10.1007/0-306-47919-2_13 |
2003-01-01 | Trans -resveratrol, found in wine, grapes, peanuts, soy and tea, is one constituent of the polyphenol class which is reported to be beneficial to animal health. The analysis of trans -resveratrol may be accomplished by use of solid-phase microextraction (SPME), with on-fibre derivatization in order to improve the subsequent GC analysis (to increase the volatility and recovery) of the extracted solute. An 85 μm polyacrylate SPME fibre was selected for this study, and the SPME method incorporated a modification to the procedure to remove moisture and permit the use of water sensitive derivatizing reagents. Both BSTFA and acetic anhydride reagents were tested. Comprehensive two-dimensional gas chromatography (GC×GC) with a cryogenic modulation system was employed for the final chromatographic separation step. It was found that successful separation of resveratrol derivatives from potential interferences, that cause peak overlap in single column GC analysis of complex red wine samples, could be achieved. This increased separation power allows more accurate quantitative results for extracted trans -resveratrol Reproducible positioning of the trans -resveratrol peak in the 2D separation space was found in the SPME-GC×GC experiment, consistent with other studies on GC×GC retention reproducibility. Calibration curves for peak area were prepared for SPME extracted resveratrol, for both derivatising reagents, and good linearity (R^2 ca. 0.998) was achieved. The trans -resveratrol content of five Australian red wine samples was determined by using the acetic anhydride derivatizing reagents, and optimum conditions for the analysis were established. | Solid-phase microextraction—On-fibre derivatization with comprehensive two dimensional gas chromatography analysis oftrans-resveratrol in wine | 10.1007/BF02492127 |
2003-01-01 | The Air Force Research Laboratory (AFRL) Space Vehicles Directorate is actively pursuing cryocooler and cryogenic integration research to support technology needs for the Air Force, the Missile Defense Agency (MDA, formerly the Ballistic Missile Defense Organization), and the Department of Defense (DoD). This paper presents an overview of the in-house and external applied research efforts on a number of fundamental issues toward the development of long-life strategic cryocoolers and cryogenic integration technology. External activities include Small Business Innovative Research (SBIR) development, AFRL funded activities at the National Institute for Standards and Technology (NIST), and funded research at Oxford University. In house research efforts include work on advanced regenerators for Stirling cycle cryocoolers, and continued in-house research on products from the SBIR program. Additionally, this paper examines future research trends for AF and DoD cryogenic technology. | Air Force Research Laboratory Space Cryogenic Technology Research Initiatives | 10.1007/0-306-47919-2_2 |
2003-01-01 | This study presents a state-of-the-art summary of the applications of low temperatures and cryogenics to clinical situations and underlying principles. The effects of low temperature on mammalian systems in the absence of ice are explained together with the effects of hypothermia. Low-temperature storage of tissues and organs for transplantation in the liquid state is addressed. The additional issues associated with the formation of ice and subsequent freezing of cells and tissues as well as organ cryopreservation are treated. Only engineering aspects are included. | Low Temperature and Cryogenic Applications in Medicine and Surgery | 10.1007/978-94-010-0099-4_17 |
2003-01-01 | Hydrogen sorption cryocoolers are being developed for the European Space Agency Planck mission to provide nominal 19 K cooling to instruments for measuring the temperature anisotropy ofthe cosmic microwave background with extreme sensitivity and resolution. The behavior of the metal hydride sorbent beds used in the compressor dominates both the performance and reliability of these sorption cryocoolers. The compressor elements have been designed to minimize their input power requirements and to enhance durability during extended temperature cycling while in operation. The Lanthanum-Nickel-Tin alloy LaNi_4.78Sn_0.22 in the sorbent beds circulates and compresses the hydrogen refrigerant gas while the ZrNi alloy is used to provide variable pressure in the gas-gap heat switches for each compressor element. Characterization tests have been performed on the compressor elements built for an Engineering Bread Board (EBB) cooler to evaluate the behavior of both the sorbent bed and gas-gap switches under conditions simulating flight operation. These results provide a basis for predicting EBB cooler performance and to identify any design deficiencies prior to fabrication of the flight compressor elements. In addition, experiments were done on compressor elements that had been operated up to several thousand cycles to assess degradation in the sorbent hydride and reduction in the effectiveness of the gas gap switches in reducing parasitic heat losses | Evaluation of Hydride Compressor Elements for the Planck Sorption Cryocooler | 10.1007/0-306-47919-2_83 |
2002-12-01 | SRFQ2 is the second RFQ superconducting (SC) structure of PIAVE, the positive ion injector of the SC LINAC for heavy ions ALPI, in operation at Legnaro. During 2001, SRFQ2 was extensively tested at cryogenic temperature reaching its design performance, i.e., 280 kV inter-electrode voltage (equivalent to 25 MV/m peak surface electrical field) at 7 W dissipated power. This paper describes the treatments, the main difficulties arisen during the tests, the way they were overcome and the measurement sequences that allowed the characterization of SRFQ2 behavior. A brief description of future programs is also given. | Cryogenic, superconducting and rf results of the SRFQ2 of PIAVE | 10.1007/s12043-002-0146-9 |
2002-11-01 | A superconducting linear accelerator (LINAC) to boost the energy of the heavy ion beams from the 14 UD pelletron accelerator at Mumbai is under development. The booster is based on quarter wave resonators (QWR) coated with lead which is superconducting at liquid helium temperature. The operating frequency is 150 MHz. Four resonators each are mounted in a cryostat module built indigenously. A total of seven such modules arranged in two arms with an isochronous and achromatic beam bend in the middle comprises the full LINAC. The transverse focusing of the beam through the LINAC is carried out using periodic quadrupole doublet magnets operating at room temperature. The present status of the project is described. | Development of a superconducting LINAC booster for the pelletron at mumbai | 10.1007/s12043-002-0095-3 |
2002-10-01 | The effect of cryogenic treatments on 7075 aluminum alloy | 10.1361/105994902770343683 | |
2002-09-01 | Cryogenic Engineering for Fast Freezing of Foodstuffs | 10.1023/A:1022076907594 | |
2002-09-01 | Stages of Development of Cryogenic Systems for Space Rocket Technology | 10.1023/A:1022024923524 | |
2002-08-01 | Xinetics is working with NASA to develop a cryogenic deformable mirror technology to meet the specific needs of the Next Generation Space Telescope. One of the critical technical issues is the development of a cryogenic actuator with sufficient displacement and temperature stability. This paper discusses the two year effort to achieve a cofired electroceramic multilayered cryogenic actuator. The development began by testing materials from 300 to 35 K via a cut and bond actuator technology that led to a cryogenic electroceramic material down selection. After selecting a doped SrTiO_3, a cofired actuator process specific to the cryogenic ceramic was developed. The assembled cryogenic actuators achieved the 3 μm displacement (stroke) between 35 and 65 K required by the deformable mirror design. The discrete cryogenic actuators were assembled into an engineering model cryogenic 349-channel deformable mirror that was delivered to NASA in October 2001. | Cryogenic Cofired Multilayer Actuator Development for a Deformable Mirror in the Next Generation Space Telescope | 10.1023/A:1020551812502 |
2002-06-01 | A simple method combining slurry sampling after cryogenic grinding and the use of a permanent modification of the integrated platform inside the transversely heated graphite atomizer (THGA) was proposed for the determination of Cd and Pb in foods. Potentialities of the cryogenic grinding were evaluated for grinding different materials of difficult homogenization such as high fat and high fiber tissues. Animal and vegetal samples were cut into small pieces and ground in liquid nitrogen for 2 min. Slurries were prepared directly in the autosampler cup after cryogenic grinding by transferring an exact amount of homogeneous powdered material (5–20 mg) to the cup, followed by 1.00 mL of 0.2% (v/v) HNO_3 containing 0.04% (v/v) Triton X-100 and sonication for 30 s, before transferring into the platform previously coated with 250 µg W and 200 µg Rh. Use of a tungsten carbide-rhodium permanent modifier combined with NH_4H_2PO_4 conventional modifier improves tube lifetime and increases the pyrolysis temperature for Cd. Homogeneity tests, carried out by comparing the between- and within-batch precision for each kind of sample, showed no significant differences at the 95% confidence level, indicating good homogeneity for 5–20 mg masses. Detection limits were 3.3 ng g^–1 Cd and 75 ng g^–1 Pb for 1% m/v slurries. Results for determination of Cd and Pb in foods slurries were in agreement with those obtained with digested samples, since no statistical differences were found by the paired t -test at the 95% level. | Determination of Cd and Pb in food slurries by GFAAS using cryogenic grinding for sample preparation | 10.1007/s00216-002-1296-9 |
2002-06-01 | Cryogenic X-ray crystallography has heen applied to investigate thehydration structures of proteins. The amount of hydration water moleculesidentified at cryogenic temperature is more than twice those at ambienttemperature, and the structural models of proteins with a lot of hydrationwater molecules have provided much information to elucidate the static anddynamical characteristics of hydration structures of proteins. On proteinsurface, hydration water molecules distribute non-randomly and stillretain the tetrahedral hydrogen-bond geometry as well as in bulk solvent.In addition, water molecules form clathrate-like arrangements to cover thehydrophobic residues exposed to solvent. The standard interaction geometryenables the three-dimensional extension of hydrogen-bond networks aroundprotein molecules and, simultaneously, ensures the concerted reorganizationof hydration structures during the dynamical motion of proteins at work.The hydration structure analyses at cryogenic temperatures may contributeto understanding physical principles governing the dynamics of `molecularmachines' in aqueous environment. | Structural Characteristics in Protein Hydration Investigated by Cryogenic X-ray Crystal Structure Analyses | 10.1023/A:1019982220615 |
2002-05-01 | Cryogenic oven-trapping (COT) with capillary GC has been successfully applied to analysis of chloroform, dichloromethane, trichloroethylene, diethyl ether, the components of solvent thinner (ethyl acetate, benzene, n -butanol, toluene, and others), xylene isomers, cyanide, ethanol, hexanes, general anesthetics, and styrene in human body fluids. This COT–GC technique was compared with headspace solid-phase microextraction (SPME) coupled with GC for some volatile organic compounds (VOC); for all compounds compared the sensitivity achieved using COT–GC was more than ten times higher than for headspace SPME–GC. The COT–GC method is recommended for widespread use in forensic and environmental toxicology, because it is simple, requires no special GC operations, and yet enables high sensitivity and high resolution. | Cryogenic oven-trapping gas chromatography for analysis of volatile organic compounds in body fluids | 10.1007/s00216-002-1240-z |
2002-05-01 | Inspection of the condition of the foundations of buildings and structures erected and occupied in the cryolithic zone (Noril'sk, Dudinka) has exposed laws governing strength reduction and failure of the concretes placed in the foundations. Recommendations are presented for the failsafe service of buildings and for the protection of foundations from frost damage during reconstruction. | Cryogenic Destruction of Construction Materials in Foundations of Buildings Erected in the Permafrost Zone | 10.1023/A:1020372002621 |
2002-04-01 | A revised version of the Griffin & Holland ideal semiconductor bolometer model is presented and its use in determining bolometer properties and parameters from experimental load curve measurements is discussed. We show that degeneracy between some bolometer parameters can only be broken by model fitting a family of load curves over a range of bath temperatures, and that measurements with the bolometer blanked (zero absorbed radiant power) are essential for unambiguous determination of the main parameters. The influence of measurement errors on parameter recovery is analysed using synthetic noisy data sets. | Thermal Modelling and Characterisation of Semiconductor Bolometers | 10.1023/A:1015705826900 |
2002-04-01 | We describe techniques for testing and characterising semiconductor bolometers, using the bolometer model presented in Sudiwala et. al. [1]. The procedures are illustrated with results from a prototype bolometer for the high frequency instrument (HFI) in the Planck Surveyor cosmic microwave background mission. This is a bolometer using spider-web geometry and a neutron transmutation doped (NTD) germanium thermistor, designed for operation at 100 mK. Details are given of the laboratory facility used to take data at temperatures from 70 mK to 350 mK. This employs an adiabatic demagnetisation refrigerator to cool the detector and optics. The spatial and spectral properties of the optical system are controlled using feedhorns and edge filters. To characterise the bolometer, blanked and optically loaded load curves were measured over a range of temperatures, and the response to modulated radiation was measured as a function of modulation frequency, temperature and bias current. Results for the prototype bolometer show that its behaviour is well represented by an ideal thermal detector down to a temperature of approximately 100 mK. Below this, non-thermal effects such as electron-phonon decoupling or electric field dependent resistance appear to lead to departure from ideal behaviour. The performance was in good agreement with the design goals for the bolometer. | High Precision Characterisation of Semiconductor Bolometers | 10.1023/A:1015757810970 |
2002-04-01 | Thermal detectors are introduced and their possible impact on neutrinoless double-beta-decay (2β0ν) search is discussed. The thermal experiment MIBETA is described, reporting the up-to-date limits on ^130Te and ^128Te. A new generation experiment, consisting in a large expansion of MIBETA and known as CUORE, is presented and discussed. | Present and Future Cryogenic Experiments on Double-Beta Decay | 10.1023/A:1015361411086 |
2002-04-01 | The solubilities of solid 1-hexyne in liquid argon at 87.3 and in liquid nitrogen at 77.4 K have been measured by the filtration method. The hydrocarbon contents in solutions were determined using gas chromatography. GC–MS was used to identify impurities in 1-hexyne. The experimental value of the mole fraction solubility of solid 1-hexyne in liquid argon at 87.3 K is (0.85 ± 0.19) × 10^−7 and (1.25 ± 0.08) × 10^−8 in liquid nitrogen at 77.4 K. The Preston–Prausnitz method was used for calculation of the solubilities of solid hydrocarbon in liquid argon in the temperature range 84.0–110.0 K and in liquid nitrogen from 64.0 to 90.0 K. The solvent–solute interaction parameters l _12 were also calculated. At 90.0 K liquid argon is a better solvent for solid 1-hexyne than is liquid nitrogen. | Solubility of Solid 1-Hexyne in Liquid Argon and Nitrogen at the Standard Boiling Points of the Solvents | 10.1023/A:1015825102964 |
2002-03-01 | Headspace solid-phase micro-extraction (HS SPME), comprehensive two-dimensional GC (GC×GC), and flame ionization detection (FID) have been examined for their suitability and compatibility for rapid sampling, separation, and detection of garlic flavour volatiles. This approach (HS-SPME-GC×GC-FID) is distinctly superior to use of one-dimensional GC, i. e., HS-SPME-GC-FID. Direct comparison of the experimental results showed that a 10–50-fold increase in sensitivity is obtained, separating power is substantially enhanced, and the peak capacity is up to ten times higher. As a consequence, much more detailed flavour analysis can be performed; this results in better information about the aroma-active compounds. | Application of solid-phase micro-extraction and comprehensive two-dimensional gas chromatography (GC×GC) for flavour analysis | 10.1007/BF02491673 |
2002-02-01 | Amplification properties of continuous VUV emission of cooled discharge in mixtures of heavy inert gases are studied experimentally. The discharge current is 10–50 mA, the pressure is 100 GPa. Results pointing to amplification near the resonance line of xenon λ=146.96 nm are obtained. The amplification coefficient is measured to be κ=0.1 cm^−1. The problem of radiation outcoupling from the active medium remains to be solved for practical implementation of a VUV laser. | Stimulated emission of inert gas mixtures in the VUV range | 10.1134/1.1454046 |
2002-01-01 | The Air Force Research Laboratory (AFRL), Space Vehicles Directorate has been the lead Department of Defense (DoD) agency for the development of low capacity cryogenic refrigerators and integration technologies for space applications since the late 1980s. High capacity cryocoolers and long term (>20 years) on orbit propellant storage are potentially enabling technology for future High Energy Laser (HEL) space systems, orbital transfer vehicles, and on orbit propellant depots. Cryogenic applications in space based systems requiring long term cryogen storage includes: significant cooling requirements for subcritical cryogens, cryocooler redundancy issues, on orbit cryogen transfer from vehicle to vehicle, large shield cooling, long term gas and liquid cryogen storage, large distributed cooling surfaces, cryogenic system integration issues, and significant spacecraft system penalties due to mass and input power. AFRL has pursued low capacity cryocooler concepts including reverse Brayton cycle, single and multiple stage Stirling cycle, advanced Joule-Thomson cycle, and Pulse Tube (Stirling cycle variant) designs. The cryocooler technology spans a wide range of cooling temperatures (from ∼10 Kelvin to 150 Kelvin) and heat loads (up to 10 Watts at 95 Kelvin). Additionally, AFRL has pursued advanced cryogenic integration technology including cryogenic thermal switches, cryogenic heat transport, thermal storage, and cryogenic integration schemes to reduce system mass and input power penalties. Current cryogenic integration and cryocooler development programs address the negative impacts of the cryogenic system on optical space systems including: induced line of sight vibration, longevity, power consumption, mass, thermal transport, thermal storage, and thermal switching. However, the cryogenic cooling requirements for future Air Force systems may require large capacity cryogenic cooling, extremely mass and power efficient mechanical refrigerators, and significant improvements in long term on orbit cryogen storage. The technical efforts at AFRL concentrate on exploratory and advanced development programs that focus on | Advanced Cryogenic Integration and Cooling Technology for Space-Based Long Term Cryogen Storage | 10.1007/0-306-47112-4_91 |
2002-01-01 | This paper provides an overview of the cryogenic development activities carried out over the past 25 years by the Special Research & Development Bureau for Cryogenic Technologies (SR&DB) in the Ukraine. The SR&DB is a part of the Scientific and Technical Complex and Institute for Low Temperature Physics and Engineering, a unique center for cryogenic technology development within the ex-USSR. | Development of Cryogenic Cooling Systems at the SR&DB in the Ukraine | 10.1007/0-306-47090-X_5 |
2002-01-01 | In order to reduce wheel adhesion and improve the quality of ground surface, the ELID (electrolytic in-process dressing) grinding and cryogenic ELID grinding for grinding TC4 was developed. The various factors affecting the ground surface integrity were studied. The grinding forces were measured, grinding chips and the ground surface were studied under SEM. The grinding temperature was analyzed by using FEM. The results indicated that, by using ELID grinding and cryogenic cooling, the wheel adhesion, the grinding forces and grinding temperature were reduced and the ground surface integrity improved distinctly | Finish Surface Grinding of Titanium Alloys | 10.1007/0-306-47000-4_94 |
2002-01-01 | The present work concentrates on the measurement of the thermal resistance of a copper/Kapton MT/copper junction, in a flat-plate geometry, at cryogenic temperatures. Kapton MT is a polyimide film with alumina filler particles and has a relatively low thermal resistance, but yet a high voltage standoff capability. The thermal resistance consists of two components: thermal contact resistance at the copper/Kapton MT interfaces, and the thermal conduction resistance across the Kapton MT film. The measured thermal resistance indicates that increasing the contact pressure reduces the thermal resistance, to a limit determined by the film conduction resistance. Increasing the contact pressure and the average interface temperature, and decreasing the thickness of the interstitial layer, tends to decrease the thermal resistance. | Thermal Resistance Across the Interstitial Material Kapton MT at Cryogenic Temperatures | 10.1007/0-306-47090-X_88 |
2002-01-01 | A simulation program for viscous compressible flow has been developed to study the details of fluid motion and gas dynamics inside a pulse tube refrigerator. Axisymmetric two-dimensional Navier-Stokes equations are solved numerically. Simulation results inside of a basic-type pulse tube refrigerator have been reported in past research, and showed that secondary mass flow and enthalpy flux, going from the cold end to the hot end along the tube wall, contribute to the heat transfer. They also suggested that the boundary layer on the tube wall might play an important role in transferring enthalpy from the cold end to the hot end of the pulse tube. In order to investigate the heat transfer mechanisms within the entire pulse tube refrigerator, the present research also includes the simulation of the flow and gas dynamics inside of the regenerator and after-cooler. The simulation results are compared with experimental data. The simulation results of the pulse tube temperature profile, when compared to the experiment, are seen to be in good agreement. The simulation results appear to well describe the gas dynamics and refrigeration mechanisms of the pulse tube refrigerator. | Numerical Study of Gas Dynamics Inside of a Pulse Tube Refrigerator | 10.1007/0-306-47112-4_46 |
2002-01-01 | NIST has published at least two references compiling cryogenic material properties. These include the Handbook on Materials for Superconducting Machinery and the LNG Materials & Fluids. Neither has been updated since 1977 and are currently out of print. While there is a great deal of published data on cryogenic material properties, it is often difficult to find and not in a form that is convenient to use. We have begun a new program to collect, compile, and correlate property information for materials used in cryogenics. The initial phase of this program has focused on picking simple models to use for thermal conductivity, thermal expansion, and specific heat. We have broken down the temperature scale into four ranges: a) less than 4 K, b) 4 K to 77 K, c) 77 K to 300 K, and d) 300 K to the melting point. Initial materials that we have compiled include oxygen free copper, 6061-T6 aluminum, G-10 fiberglass epoxy, 718 Inconel, Kevlar, niobium titanium (NbTi), beryllium copper, polyamide (nylon), polyimide, 304 stainless steel, Teflon, and Ti-6Al-4V titanium alloy. Correlations are given for each material and property over some of the temperature range. We will continue to add new materials and increase the temperature range. We hope to offer these material properties as subroutines that can be called from your own code or from within commercial software packages. We will also identify where new measurements need to be made to give complete property prediction from 50 mK to the melting point. | Cryogenic Material Properties Database | 10.1007/0-306-47112-4_84 |
2002-01-01 | The Standard Advanced Dewar Assembly (SADA) is the critical module in the Department of Defense (DOD) standardization effort of second-generation thermal imaging systems. DOD has established a family of SADAs to address high performance (SADA I), mid-to-high performance (SADA II), and compact class (SADA III) systems. SADAs consist of the Infrared Focal Plane Array (IRFPA), Dewar, Command & Control Electronics (C&CE), and the cryogenic coolers. SADAs are used in weapons systems such as Comanche, the M1 Abrams tank, the M2 Bradley fighting vehicle, and the Javelin CLU. The linear drive cryocoolers maintain the Infrared Focal Plane Arrays (IRFPAs) at the desired operating temperature. Stirling linear drive cryocoolers are being used in place of Stirling rotary coolers. DOD has defined a family of tactical linear drive coolers in support of the family of SADAs. These coolers are required to have low input power, a quick cool-down tune, low vibration output, low audible noise, and higher reliability. This paper (1) outlines the characteristics of each cooler, (2) presents the status and results of qualification tests, and (3) presents the status and test results of efforts to increase cryocooler reliability. Flexure-spring designs of the 0.15 watt and 1.0 watt coolers are currently in reliability growth testing. | Status of Programs for the DoD Family of Linear Drive Cryogenic Coolers for Weapon Systems | 10.1007/0-306-47112-4_2 |
2002-01-01 | This paper presents a cryogenic polishing method. The polishing liquid is frozen to ice polishing mold at first and then it is used to polish optical materials under low temperature. It has been shown by experiment that the polishing efficiency can be improved and super-smooth surface can be obtained. This is a new way to polish optical materials. | Cryogenic Polishing Method of Optical Materials | 10.1007/0-306-47000-4_77 |
2002-01-01 | Silicon-on-insulator (SOI) layers showed their perspectives of application in cryogenic electronics [ 1 ]. An aim of the studies presented was to investigate perspectives of their use in the development of mechanical and temperature sensors for operation at cryogenic temperatures. The laser recrystallization represents a technique providing adjustment of the electrical and piezoresistive parameters of polysilicon layers. That is why such a method has been used in the studies presented. | Laser-Recrystallized SOI Layers for Sensor Applications at Cryogenic Temperatures | 10.1007/978-94-010-0339-1_17 |
2002-01-01 | This paper describes BEI’s efforts in producing a one watt pulse tube cooler, the CryoPulse 1000, for commercial applications. The cooler was designed by a computer model which has been validated against various Stirling and pulse tube coolers in the literature.^1–8 The cooler was designed, fabricated and tested. Preliminary testing showed that the CryoPulse 1000 produces good cooling. However, the heat exchanger at the hot end of the regenerator needs to be modified to more efficiently reject the heat energy generated. Detailed test results will be presented in a future paper. | Design and Preliminary Testing of BEI’s CryoPulse 1000, the Commercial One Watt Pulse Tube Cooler | 10.1007/0-306-47090-X_21 |
2002-01-01 | The SR&DB in a joint project with the U.S. Air Force Research Laboratory and Orbita Ltd. (USA) has developed a concept for a periodically-operating long-life (5 to 10 years) refrigeration system for providing periodic cooling at 5-10 K. The design goal for the system cooling capacity is 0.5 W during 20% of the time. Conducted analyses have shown that the task is best met with a combined system using a two-stage Stirling cryocooler upper stage together with a helium Joule-Thomson (J-T) throttle cooler for the lower stage. The system also incorporates cold accumulators at 65-85 K (using the melting of nitrogen or argon) and at 20–26 K (using the melting of deuterium or neon) to precool the helium in the J-T system. The cold accumulators are cooled periodically (or permanently) by a two-stage split-Stirling cryocooler. The periodic 5–10 K load is met by operating the helium Joule-Thomson throttle cooler on demand. The throttle cooler is based on a lubrication-free piston compressor with clearance seals that was developed by the SR&DB. The problem of continuous cooling at 5–10 K was also examined based on the use of an appropriate cold accumulator. Helium is a candidate material for the cold accumulator; or other substances having appropriate physical characteristics (various kinds of phase transitions in the 4–10 K temperature range) could be used. | Long-life 5–10 K Space Cryocooler System with Cold Accumulator | 10.1007/0-306-47090-X_63 |
2002-01-01 | Experimental results on a gaseous hydrogen / liquid oxygen spray flame are compared with a simplified model. The gasification rate, which depends on rates of turbulent mixing and vaporization, has a strong effect on flame structure. The rate-limiting process is vaporization at subcritical pressures and turbulent mixing at supercritical pressures. This is because surface tension and the latent heat of vaporization tend to zero above the critical pressure. | Turbulent Combustion of Sprays under Supercritical Conditions | 10.1007/978-94-017-1998-8_38 |
2002-01-01 | One means of achieving high reliability with cryogenic payloads involving cryocoolers is to incorporate redundancy, either in the form of redundant coolers and/or redundant drive electronics. To access the redundant elements, electrical and/or heat switches must also be incorporated. Although the redundant elements protect against a possible failure, the increased system complexity and increased cryogenic load associated with the incorporation also have a negative effect on reliability that must be taken into account. This paper presents an analysis of the reliability advantages and disadvantages of a variety of cryocooler redundancy options, based on their total reliability, mass, and power impact at the cryogenic system level. The paper begins with developing an approach for quantifying the probability of failure of the key subassemblies, such as coolers, electronics, and heat switches, associated with the redundancy; the analysis considers the subassembly’s state of development, the complexity and testability of its critical failure mechanisms, and the effect of the total cryogenic load on its reliability. Means are also presented for estimating the total cryogenic load as influenced by the addition of the redundant elements. Finally, the overall system performance (reliability, mass, and power) of the various cryocooler redundancy options is computed using the failure probabilities of the individual elements, and the system interrelationships of the elements. | Cryocooler Reliability and Redundancy Considerations for Long-Life Space Missions | 10.1007/0-306-47112-4_79 |
2002-01-01 | An introduction to gases and the gases industry | 10.1007/0-306-47371-2_1 | |
2002-01-01 | The recent developments of carbonaceous material synthesis have resulted in several new forms of carbon such as carbon nanotubes and carbon nanofibers, and super-high surface area activated carbons nano-materials. There are speculations that these materials may have extraordinarily high hydrogen storage capacities. In this work, we examined the hydrogen gas adsorption capacities of these carbonaceous materials at room temperature, as well as at liquid nitrogen temperature, to elucidate the hydrogen storage potential of these materials. Experimental results indicated that none of these materials showed significant hydrogen storage capacities at room temperatures, and only super-high surface area activated carbon showed attractive gravimetric hydrogen storage at cryogenic temperature, of over 5.4% by weight at 77 K and at 300 psi hydrogen gas pressure. However, the nanocarbon materials produced from the activation of fullerene (AC-C60), and vacuum soot (AC-VAS) showed increased hydrogen adsorption capacity compared to the best commercial super-high surface area activated carbons. In addition, nanotubes showed enhanced storage capacity for their surface area. The challenge is to further modify nanotubes materials to achieve high surface area and consequently high hydrogen storage capacity. | Physical Hydrogen Storage on Nanotubes and Nanocarbon Materials | 10.1007/978-94-010-9598-3_30 |
2002-01-01 | Current space cryocooler developments have achieved performance and capability that have made the use of active refrigeration in space missions feasible. Space flight demonstrations such as the Sandia National Laboratory Cobra Brass and Multispectral Thermal Imager missions, the National Aeronautics and Space Administration SABER, Hyperion, and AIRS missions baselined and implemented active refrigeration to achieve mission goals. The NASA retrofit of the NICMOS cooling system on the Hubble Space Telescope, due to be installed during a 2001 servicing mission, will use a reverse Brayton cycle cryocooler to provide cooling for the NICMOS sensor due to a prematurely depleted cryogen dewar. These applications of cryocooler technology validate the improved mission capabilities and reliability and lifetime confidence in active refrigeration in space. Past development efforts have focused primarily on reliability and the achievement of long life. However, looking ahead at 21 st century military space applications, there are improvements needed in several aspects of current cooling technology including higher capacity cooling loads, mass reduction, and improvement in efficiency, low temperature performance, and lifetimes greater than 10 years. In addition, cryogenic integration technology must be developed to allow efficient cryocooler to cooled component integration. Significant improvements in cryocooler technology can easily be overshadowed by gross parasitic heat loads and unacceptable cryogenic system penalties. This paper focuses on mid-term and out-year cooling requirements for the Air Force Space Based Infrared System Low, Space Based Laser, Advanced Space Based Infrared System, and other Department of Defense space missions. | Military Space Cryogenic Cooling Requirements for the 21st Century | 10.1007/0-306-47112-4_1 |
2002-01-01 | Refrigeration | 10.1007/0-306-47061-6_3 | |
2002-01-01 | A design manual titled “Low Temperature Pulse Tube Coolers”” has been developed for use in a university course on the design of cryogenic machines. It allows students to be involved in the entire design process by using simple mathematical solutions of the rather difficult physical processes that exist in cryogenic gas machines with pulse tubes. Using the manual, students fulfill a real design of a pulse tube cooler. The manual consists of two parts. The first part treats a variety of topics including: 1) details of the thermal-physical processes involved and their mathematical modeling, 2) the “method of characteristics” for solution of the equations of gas dynamics, and 3) the definition and discussion of the principal items of cooler losses. For performing calculations, the students use object oriented programming, since examining pulse tube modifications parametrically has group properties. The construction of a model for optimization permits the students to find the optimum solution among all device modifications. The check of a chosen optimum device with appropriate parameters can be conducted with a more complex mathematical model, which is presently under development. Skill at reviewing and understanding the technical literature and, in particular, the patent literature has a large significance in designing. In the second part of the design manual one can find a literal description of the existing patents and tasks for the development of skills for the analysis of such materials. The design process for a given technology can last several semesters and includes elements of scientific research work. To reduce the designing course length, “design teams” can be formed; here a group of students with various participating roles fulfill the work. The group can consist of the students of 3rd-5th years of learning. | Pulse Tube Modeling as a Means of Teaching the Design of Cryogenic Refrigerators | 10.1007/0-306-47090-X_49 |
2002-01-01 | The thermal contact conductance across an epoxied copper junction loaded with Ag (silver) particles was investigated at cryogenic temperatures. Thermal contact conductance, or its inverse, thermal contact resistance, consists of two components: thermal contact resistance at the copper/Ag-particle epoxy interfaces, and the thermal conduction resistance across the Ag-particle epoxy slab. The effects of the Ag-particle volume fraction, and the average interface temperature of the epoxied junction are both evaluated. Increasing the Ag-particle fraction increases the conductance above that for a plain epoxied sample, by as much as one order of magnitude for a Ag particle fraction of 30%. A critical Ag particle volume fraction is observed in the measurements, below which value the thermal conductance of the epoxied junction increases only slightly with increasing particle fraction. | Experimental Results on the Thermal Contact Conductance of Ag-Filled Epoxied Junctions at Cryogenic Temperatures | 10.1007/0-306-47112-4_85 |
2002-01-01 | The SR&DB has adopted the use of cold accumulators in conjunction with a cryocooler as the key means of achieving multi-year life cryogenic cooling systems. The approach involves cyclical operation of the cooler with low duty cycle, while the continuous cryogenic load is supplied by the thermoaccumulator which contains a melting-freezing, evaporation-condensation, or other type of thermal phase transition material. The cryocooler is typically either a Joule-Thomson (J-T) throttle cycle based on mixed gases, or a split-Stirling cryocooler. Such cyclical operation increases system lifetime by up to 20 times. By changing the J-T working fluid and the phase change material it is possible to address a broad range of temperatures (4 – 150 K). Often the system can be upgraded to different operating temperatures without any changes in the cryocooler or accumulator hardware; only a replacement of the operating medium is required. | Cold Accumulators as a Way to Increase Lifetime and Cryosystem Temperature Range | 10.1007/0-306-47090-X_81 |
2002-01-01 | Wear and internal contamination are two of the primary factors that influence reliable, long-life operation of turbo-Brayton cryocoolers. This paper describes tests that have been conducted and methods that have been developed for turbo-Brayton components and systems to assure reliable operation. The turbomachines used in these coolers employ self-acting gas bearings to support the miniature high-speed shafts, thus providing vibration-free operation. Because the bearings are self-acting, rubbing contact occurs during start-up and shutdown of the machines. Bearings and shafts are designed to endure multiple stop/start cycles without producing particles or surface features that would impair the proper operation of the machines. Test results are presented that document extended operating life and start/stop cycling behavior for machines over a range of time and temperature scales. Contaminants such as moisture and other residual gas impurities can be a source of degraded operation if they freeze out in sufficient quantities to block flow passages or if they mechanically affect the operation of the machines. A post-fabrication bakeout procedure has been successfully used to reduce residual internal volatile contamination to acceptable levels in closed-cycle systems. The process was developed during space qualification tests on the Near Infrared Camera/Multi-Object Spectrometer (NICMOS) Cryogenic Cooler (NCC). Moisture levels were sampled over a seven-month time interval following the initial bakeout confirming the effectiveness of the technique. A description of the bakeout procedure is presented. | Life and Reliability Characteristics of Turbo-Brayton Coolers | 10.1007/0-306-47112-4_62 |
2002-01-01 | This paper presents an overview of the cryogenic refrigerator and cryogenic integration programs in development and characterization under the Cryogenic Technology Group, Space Vehicles Directorate of the Air Force Research Laboratory (AFRL). The vision statement for the group is to support the space community as the center of excellence for developing and transitioning space cryogenic thermal management technologies. The primary customers for the AFRL cryogenic technology development programs are Ballistic Missile Defense Organization (BMDO), the Air Force Space Based Infrared System (SBIRS) Low program office, and other DoD space surveillance programs. This paper will describe the range of Stirling, pulse tube, reverse Brayton, Joule-Thomson cycle cryocoolers, and sorption cryocoolers currently under development to meet current and future Air Force and DoD requirements. The AFRL customer single stage cooling requirements at 10 K, 35 K, 60 K, 150 K, and multi-stage cooling requirements at 35/60 K are addressed. In order to meet these various requirements, the AFRL Cryogenic Technology Group is pursuing various strategic cryocooler and cryogenic integration options. The Air Force Research Laboratory is also developing several advanced cryogenic integration technologies that will result in the reduction in current cryogenic system integration penalties and design time. These technologies include the continued development of the Cryogenic Systems Integration Model (CSIM), 60 K and 100 K thermal storage units and heat pipes, cryogenic straps, thermal switches, and development of an Integrated Lightweight Cryogenic Bus (CRYOBUS). | Air Force Research Laboratory Cryocooler Technology Development | 10.1007/0-306-47090-X_2 |
2002-01-01 | Plasma-dust structures at cryogenic temperatures | 10.1134/1.1450655 | |
2002-01-01 | We have integrated a 4 K mechanical cryocooler with a three stage ^ 4 He/ ^ 3 He/ ^ 3 He sorption refrigerator to achieve cooling down to 0.25 K. The cryocooler consists of two Gifford-MacMahon stages which cool ^4He to below its inversion temperature for use in a Joule-Thomson expansion stage. This in turn provides cooling below the critical temperature of ^4He. The sorption refrigerator is specified to achieve a heatlift of 3 microwatts at 0.25 K for 12 hours. This cryogenic system will be used for cooling of the bolometric detectors and optics in the Polatron, a ground-based receiver for measurement of the polarisation of the cosmic microwave background radiation at a frequency of 90 GHz. Cooling of sensitive detectors by mechanical cryocoolers can lead to sensitivity degradation due to a combination of microphonic pickup, electromagnetic interference and thermal dissipative heating. We describe the design features incorporated at system level to mitigate these effects. The Polatron also serves as a testbed for technologies to be used on the High Frequency Instrument on the ESA/NASA Planck satellite to measure the temperature anisotropies and polarisation of the cosmic microwave background radiation. | Closed-Cycle Cooling of Infrared Detectors to 0.25 K for the Polatron | 10.1007/0-306-47112-4_72 |
2001-12-01 | Phenomena such as flame propagation, flame/spray interaction and flame stabilization during the transient ignition process in a cryogenic model rocket combustor are investigated on sub-millisecond time scale. Diagnostic techniques developed to characterize the stationary spray flame are applied to investigate the transient evolution of the LOX-spray and the flame front during the ignition process. Ignition is initiated by focusing a pulsed laser into the combustion chamber. Thus, ignition time as well as the position of ignition is well defined. This and the exact control of the delay between ignition and detection time allowed the observation of the evolution of the flame front. The distribution of the liquid oxygen phase and the velocity of LOX droplets and ligaments are determined by light sheet techniques using a double-pulsed laser system. Simultaneously the position of the flame front is measured by recording the spontaneous emission of the OH-radical. By varying the delay time t between ignition and detection in a series of test runs, the transient ignition phenomena has been investigated in the interval from 0 to 5 ms after ignition. | Simultaneous observation of liquid phase distribution and flame front evolution during the ignition transient of a LOX/GH_2-combustor | 10.1007/BF03183899 |
2001-11-01 | High-Strength Stainless Steels with “Microduplex” Structure for Cryogenic Applications | 10.1023/A:1014848905691 | |
2001-10-01 | A simple and sensitive method is presented for determination of styrene, toluene, ethylbenzene, isopropylbenzene and n -propylbenzene in human body fluids by capillary gas chromatography (GC) with cryogenic oven trapping. After heating a blood or urine sample containing each compound and p -diethylbenzene (internal standard, IS) in a 7.0-mL vial at 60°C for 20 min, 5 mL of headspace vapor was drawn into a glass syringe and injected into a GC. All vapor was introduced into an Rtx-Volatile middle bore capillary column in splitless mode at oven temperature of 20°C to trap entire analytes, and the oven temperature then programmed to 280°C for GC measurements by flame ionization detection. The present conditions gave sharp peaks of each compound and IS, and low background noises for whole blood or urine samples. | Sensitive determination of styrene and related compounds in human body fluids by headspace capillary gas chromatography with cryogenic oven trapping | 10.1007/BF02491208 |
2001-09-01 | The solubilities of solid 1-hexene and 2-methylpentane in liquid argon at a temperature of 87.3 K and in liquid nitrogen at 77.4 K have been measured by the filtration method. The hydrocarbon contents in solutions were determined using gas chromatography. The experimental value of the mole fraction solubility of solid 1-hexene in liquid argon at 87.3 K is (3.87 ± 0.74) × 10^−7 and (7.94 ± 2.47) × 10^−9 in liquid nitrogen at 77.4 K. The experimental value of the mole fraction solubility of solid 2-methylpentane in liquid argon at 87.3 K is (1.45 ± 0.36) × 10^−5 and (6.80 ± 2.16) × 10^−8 in liquid nitrogen at 77.4 K. The Preston–Prausnitz method was used for calculation of the solubilities of solid hydrocarbons in liquid argon in the temperature range 84.0–110.0 K and in liquid nitrogen from 64.0 to 90.0 K. The solvent–solute interaction parameters 1 _12 were also calculated. At 90.0 K, liquid argon is a better solvent for solid 1-hexene and 2-methylpentane than is liquid nitrogen. | Solubility of Solid 1-Hexene and 2-Methylpentane in Liquid Argon and Nitrogen at the Standard Boiling Points of the Solvents | 10.1023/A:1012232131905 |
2001-08-01 | The tensile, impact, and fracture toughness tests from ambient temperature to 77 K were carried out on 32Mn-7Cr-0.6Mo-0.3N austenitic steel. The fracture surfaces and the phase constitution were analyzed using scanning electron microscopy and x-ray diffraction. The results show that the relation between yield strength and temperature is σ_0.2 · 300 + 1392.4 exp (−0.0106 T ). The 77 K yield strength is 883 MPa · m^1/2 and the K _ J 0.05 value is about 236 MPa · m^1/2. The cryogenic intergranular fracture is fully suppressed. The 77 K fracture surfaces exhibit a tough character composed of many dimples and few small quasi-cleavage facets. The results of x-ray analysis show that the austenite phase of the steel is stable even under cryogenic deformation conditions. | Mechanical properties of 32Mn-7Cr-0.6Mo-0.3N austenitic steel for cryogenic applications | 10.1361/105994901770344881 |
2001-08-01 | Thermal singular stress problem for glassfiber reinforced plastics with surface cracks at cryogenic temperatures is considered. For the case of the crack which is normal to and ends at the interface between orthotropic elastic materials, the order of stress singularity around the tip of the crack is obtained. Fourier transforms are used to formulate the problem in terms of a singular integral equation. The singular integral equation is solved by using the Gauss–Jacobi integration formula. Numerical calculations are carried out for the cases of embedded and edge cracks, and the thermal stress intensity factors at different temperatures are shown graphically. | Thermal singular stresses of glassfiber reinforced plastics with surface cracks at cryogenic temperatures | 10.1023/A:1010897419234 |
2001-06-01 | Spurious transient outputs of a piezoelectric accelerometer have been observed when the accelerometer is attached to a surface undergoing rapid cool-down to a cryogenic temperature. Such conditions occur in cryogenic propellant rockets on assemblies such as feedlines and turbopumps. Under exposure to liquid oxygen, surface temperatures can drop to near −300°F in a matter of minutes. The occurrence of spurious output depends on the internal construction of the accelerometer and on the effectiveness of thermal isolation provided by the mounting for a susceptible accelerometer. Specifically, an Endevco Model 2271AM20 charge-mode, compression-type accelerometer (CTA) has been observed to produce intermittent spurious output spikes during flight of a launch vehicle, during ground test firing of a rocket engine and in laboratory experiments. It is suggested that this spiking, also known as the pyroelectric effect, can be attributed to charge buildup due to thermal effects in the piezo-electric crystal stack. In the case studies, sporadic jumping of this charge across a gap at the outer edge of the plating on the crystal stack face is believed to cause momentary saturation of the charge amplifier. A replacement Endevco Model 7722 shear-type accelerometer (STA) using a different type of crystal arrangement as well as a different crystal material proved to eliminate these spurious charge jumps in a series of laboratory tests. This paper presents the results of experiments conducted to evaluate both the CTA and the STA. The effectiveness of different mounting configurations, used to provide thermal isolation sufficient to eliminate the spikes from the CTA, was evaluated. It is also suggested that observations of a particular type of nonzero mean signal in the time domain and broad, elevated, low-frequency content in the frequency spectrum can be useful in detecting the presence of pyroelectric-induced transients, even if the spikes are visually buried within high-amplitude vibration data. | Accelerometer spiking under cryogenic conditions | 10.1007/BF02323194 |
2001-05-01 | Cryopreservation has become anessential tool for operational application offorest tree embryogenic cultures, due to thelong evaluation periods needed for treesregenerated from these cultures. Fiveyellow-poplar ( Liriodendron tulipifera )and seven sweetgum ( Liquidambar spp. )embryogenic culture lines werestored in liquid nitrogen for 48 hours, afterwhich they were thawed and tested for regrowthand ability to produce somatic seedlings.Combinations of two sorbitol pretreatments andthree dimethylsulfoxide (DMSO) cryoprotectantlevels were evaluated for their impact onrecovery following cryogenic storage. The bestresults were obtained with 0.4 M sorbitol and5% DMSO, which provided 100% recovery.Somatic seedlings were regenerated from allculture lines and treatments, except for atransgenic sweetgum line. | Cryopreservation of yellow-poplar and sweetgum embryogenic cultures | 10.1023/A:1012237606373 |
2001-03-01 | Phospholipids and fatty acids in chitin and chitosan samples undergo qualitative and quantitative changes upon cryogenic treatment | Effect of Low Temperature on the Lipid Component of Chitin and Chitosan Structures | 10.1023/A:1012318617263 |
2001-01-01 | Dry etch technology using high density plasma (HDP) sources has become an essential technique for the fabrication of advanced three-dimensional microelectromechanical systems (MEMS), for instance accelerometers and gyroscopes. These devices consist of sensors and micro-actuators integrated with electronic control circuitry. The sensing and actuating parts consist of features with different sizes and shapes from submicron to millimeter scale. The main advantages of plasma etch technology are high aspect ratio (depth to width ratio), high etch rate and superior dimension (width) and profile (anisotropy) control. This leads to sensitive devices that occupy small silicon area. | Limitations and Complementary Value of Cryogenic SF_6-O_2 and Bosch Plasma Etch Process for Silicon Micromachining | 10.1007/978-94-010-0840-2_16 |
2001-01-01 | One of the crucial factors which have influenced the development of cryosurgery is the standard and the technical competency of cryosurgical devices; i.e., the efficiency of cryosurgery in curative practice first of all depends on the technical proficiency of the cryosurgical devices used to perform cryooperations. | Cryosurgery and Cryotechnology — Future Safety in Medicine | 10.1007/978-3-7091-6225-5_2 |
2001-01-01 | Any newcomer to the field of infrared will be surprised at the range of different device technologies covered in the remaining chapters of this book. The reason for the wide choice is that there is no single device technology that satisfies the broad range of applications and operating conditions. For example: HgCdTe detectors can achieve much higher sensitivities than thermal detectors but the present need for cryogenic cooling, slower time to operation and higher power consumption may override the higher sensitivity for many applications. There are a large number of parameters that need consideration when selecting a detector technology. The purpose of this introductory chapter is therefore two-fold. The first is to introduce some of the commonly used parameters and measurement techniques that are referenced in the later chapters. The second is to indicate the strengths and weaknesses of different infraredi technologies. | Assessment of Infrared Materials and Devices | 10.1007/978-1-4615-1607-1_2 |
2001-01-01 | The Membrane-Bound Iron-Sulfur Proteins (FeS-A and FeS-B): Secondary Electron Acceptors of Photosystem I | 10.1007/0-306-48136-7_29 | |
2001-01-01 | Over that past four decades, the trend in the electronic industry has been to increase functional density and system performance, and to decrease cost with time. This has largely been made possible by the down-scaling of device dimensions, increased integration densities and improved fabrication technologies. However, the continued down-scaling of devices and interconnections is expected to meet technological and physical limitations, due to, for example, proper device operation or heat removal considerations. In fact, the continued reduction of the device dimensions (for example field-effect transistors, FETs), will not lead to improvements beyond a certain short channel length because of parasitic effects, saturation velocity effects, and high field effects, and because delays at the system level will be dominated by interconnection time constants (which do not scale with geometries) and problems associated with the increasing interconnection current densities due to their decreasing cross-sectional areas. Rather, improvements in the speed of high performance systems demand greater increases in device density than device speed, but this in turn leads to power density limitations. Thus, unless novel chip architectures, creative device and process designs, and revolutionary devices such as quantum-based devices are used, other means for achieving high speed/high density integrated circuits that are not limited by interconnection delays must be found. One approach to achieving high performance circuits and systems is to operate them at cryogenic temperatures, and it is this approach that is described in this chapter. | Circuits and Applications | 10.1007/978-1-4757-3318-1_7 |
2001-01-01 | Silicon (Si) bipolar transistor technology, despite its desirable features of fast switching speed, high transconductance, and excellent current-drive capability at room temperature (RT = 300 K), is often viewed as unsuitable for the cryogenic environment because its current gain (β = J_c/J_B), frequency response, and circuit speed typically degrade strongly with cooling [1,2]. Recent evidence [3–6] indicates, however, that careful profile design can be used to achieve respectable Si bipolar performance down to liquid-nitrogen temperature (LNT = 77 K). Even with these improvements, however, it is unlikely that conventionally designed Si bipolar technology will offer performance attractive enough to make it a serious contender to CMOS, a proven technology for cryogenic applications. | Silicon-Germanium Heterojunction Bipolar Transistor | 10.1007/978-1-4757-3318-1_4 |
2001-01-01 | Most research to date concerning the cryogenic toughness of austenitic stainless steels has concentrated on the base metal and weld metal in weldments. The most severe problem faced on the conventional austenitic stainless steel is the thermal aging degradation such as sensitization and carbide induced embrittlement. In this paper, we investigate the cryogenic toughness degradation which can be occurred for austenitic stainless in welding. The test materials are austenitic stainless JN1, JJ1 and JK2 steels, which are materials recently developed for use in nuclear fusion apparatus at cryogenic temperature. The small punch (SP) test was conducted to detect similar isothermally aging condition with material degradation occurred in service welding. The single-specimen unloading compliance method was used to determine toughness degradation caused by thermal aging for austenitic stainless steels. In addition, we have investigated size effect on fracture toughness by using 20% side-grooved 0.5TCT specimens. | Cryogenic fracture toughness evaluation for austenitic stainless steels by means of unloading compliance method | 10.1007/BF03184795 |
2001-01-01 | The Edelweiss Dark Matter Experiment is installed in the Modane Underground Laboratory since 1994. In 1997 the first detector of a 70 g heat and ionization Ge low-temperature detector built by the collaboration showed its discrimination capabilities. During the last two years the installation was upgraded, and a new generation of 70 g Ge detectors is operational. The detector environment is drastically controlled to avoid radioactive contamination. A test run with two new 70 g detectors shows a reduction by a factor of ten in the background level before 7-ray rejection which is now around 2 events/kg/keV/day. Three 320 g Ge cryogenic detectors have been constructed and are now being tested and should soon be operational in the present cryostat. A new cryostat is being built and will allow a detection volume of 100 1. It is expected to be installed in Modane next year. In a first step of 21×320 g Ge detectors, the Edelweiss-II experiment should test an important fraction of the MSSM Susy parameter space. | Status of the EDELWEISS Experiment | 10.1007/978-3-662-04587-9_38 |
2001-01-01 | The solubilities of solid hexane and cyclohexane in liquid argon at 87.3 K have been measured by the filtration method. The hexane and cyclohexane content in solution was determined using gas chromatography. The solubilities of the C_6 hydrocarbons in liquid argon at 87.3 K are (0.56 ± 0.11) × 10^-7 mole fraction for hexane and (1.04 ± 0.30) × 10^-7 mole fraction for cyclohexane. The Preston–Prausnitz method was used for calculation of the solubilities of solid hexane and cyclohexane in liquid argon in the temperature range 84–110 K. The values of the solvent–solute interaction constant l_12 were also calculated. | Solubility of Solid Hexane and Cyclohexane in Liquid Argon at 87.3 K | 10.1023/A:1005210127341 |
2001-01-01 | This paper discusses the place and role of cryology in achieving the common goal of Science in the 21-st century – scientific provision for sustainable development. Characteristic features of the period of transition from the social-economic system (SES) to the ecological-social-economic system (ESES) are analyzed. Much attention is given to the necessity of creating and developing mechanisms for the maintenance of ESES homeostasis, increasing the significance of studies and regulating the flows of resources. | Main Results of Earth Cryosphere Studies and Sustainable Development | 10.1007/978-94-010-0684-2_2 |
2001-01-01 | In the 1960s, in Nancy (eastern France), Alain Godard pioneered a programme on the experimental frost shattering of crystalline rocks. Following this, many geomorphologists from the Laboratoire de Geographie Physique in Meudon, near Paris, devoted their careers to the forwarding of our knowledge on mechanical rock weathering in low-temperature environments. This field-based approach, which focused on arctic basement regions as well as the Mittelgebirge of Europe, was reinforced by the experimental work being carried out at the Centre de Geomorphologie in Caen, at the instigation of Jean-Pierre Lautridou and Brigitte Van Vliet-Lanoe, and at the Laboratoire Rhodanien de Geographie in Lyon, under Bernard Etlicher and Pierre Mandier. | Cryogenic Processes and Ice-Related Restructuring of the Regolith in Metamorphic and Igneous Terrains | 10.1007/978-3-642-56821-3_7 |
2001-01-01 | Microwave filter networks represent a critical and substantive portion of any communication systems. Such a system, be it wireless or satellite, requires filters to group the signals received into channels for amplification and processing. The phenomenal growth in telecommunication industry in recent years has brought significant advances in filter technology as new communication systems emerged demanding equipment miniaturization while requiring more stringent filter characteristics. In particular, the growth of satellite communication industry has spurred tremendous activity in the area of microwave filter design and has been responsible for many advances made in this field. | Three-Dimensional Cryogenic Filters | 10.1007/978-94-010-0450-3_7 |
2001-01-01 | We review the main trends observed when cooling III–V High Electron Mobility Transistors (HEMT’s) and Heterojunction Bipolar Transistors (HBT’s) with a special interest for their high frequency (HF) properties. If there are some references dealing with the temperature parameter dependence of GaAs devices, there are few data published on InP transistors and their intrinsic parameters at low temperature (LT) down to liquid nitrogen temperature (LNT) and beyond. There is a large amount of informations available on GaAs MESFET’s, HEMT’s and HBT’s in the temperature range from 125°C to −50°C [1], but there are few ones at lower temperature. In [1] the MESFET was treated in depth, including self-heating but noise was not considered. In this chapter, section 1 is devoted to the LT carrier transport properties of the III–V semiconductors used in state of the art HF transistors. We discuss in section 2 the HEMT static, dynamic and HF noise properties at low temperature with the main emphasis on the InP HEMT. In section 3 we investigate in a similar way the low temperature behaviour of the InP HBT. As often as possible, the data are compared with corresponding performances of cooled GaAs devices and of state of the art transistors at 300K. Basic aspects about HEMT’s and HBT’s can be found in [2] and [5]. | Heterojunction Transistors at Low Temperature | 10.1007/978-1-4757-3318-1_5 |
2000-11-01 | The first research and experimental results obtained in China of high-accuracy radiometric calibration based on cryogenic radiometer are reported. Uncertainties of cryogenic radiometer and trap detectors at 7 wavelengths in the visible spectrum (488–786 nm) were less than 0.023% and 0.035% respectively, which proved the reasonability and possibility of establishing and transferring high-accuracy radiometric standards based on detectors. | High-accuracy primary and transfer standards for radiometric calibration | 10.1007/BF02909698 |
2000-11-01 | We consider the results of testing of PT3V titanium alloy (4.5% Al, 2.1% V, balance Ti) for low-cycle fatigue at temperatures of 293, 77, and 4.2 K, taking into account the influence of the degree (0.05, 1.0, and 3.0%) of plastic prestraining of the material (performed at the same temperatures) on durability. To simplify the procedure of testing and data processing and decrease the costs of testing, we apply the methods of mathematical design of experiments and factor analysis. It is shown that the maximum decrease in the durability of the tested alloy is attained for a degree of prestraining of 3% at a testing temperature of 4.2 K realized in liquid helium. | Influence of Preliminary Plastic Deformation on the Low-Cycle Fatigue of a Titanium Alloy under Conditions of Deep Cooling | 10.1023/A:1005256432723 |
2000-11-01 | Thermodynamic properties of high-pressure minerals that are not recoverable from synthesis experiments by conventional quenching methods (“unquenchable” phases) usually are calculated from equation of state data and phase diagram topologies. The present study shows that, with cryogenic methods of recovery and sample treatment, phases with a suitable decomposition rate can be made accessible to direct thermodynamic measurements. A set of samples of Ca(OH)_2-II has been synthesized in a multianvil device and subsequently recovered by cooling the high-pressure assembly with liquid nitrogen. Upon heating from liquid nitrogen to room temperature, the material transformed back to Ca(OH)_2-I. The heat effect of this backtransformation was measured by differential scanning calorimetry. A commercial differential scanning calorimeter (Netzsch DSC 404), modified to allow sample loading at liquid nitrogen temperature was used to heat the material from −150 to +200 °C at rates varying between 5 and 15 °C min^−1. The transformation started around −50 °C very gradually, and peaked at about 0 °C. To obtain a baseline correction, each sample was scanned under exactly the same conditions after the backtransformation was complete. Because of the relative sluggishness, onset and offset temperatures were not well defined as compared to fast (e.g., melting) reactions. To aid in integration, the resulting signals were successfully fitted using a generic asymmetric peak model. The enthalpy of backtransformation was determined to be Δ H = −10.37 ± 0.50 kJ mol^−1. From previous in situ X-ray diffraction experiments, the location of the direct transformation in P-T space has been constrained to 5.7 ± 0.4 GPa at 500 °C (Kunz et al. 1996). With the reaction volume known from the same study, and assuming that Δ C _ p of the transformation remains negligible between the conditions of our measurements and 500 °C, our result gives an estimate of the entropy of transition and the P-T slope of the reaction curve. To a first approximation, the values Δ S = −16.00 ± 0.65 J(mol · K)^−1 and d P/ d T = 0.0040 ± 0.0002 GPa/K have been determined. These results need to be refined by equation of state data for Ca(OH)_2-II. | The enthalpy of transformation of Ca(OH)_2-I (portlandite) to Ca(OH)_2-II (EuI_2 structure) by low-temperature DSC | 10.1007/s002690000104 |
2000-11-01 | S-Cam is a cryogenic camera for ground-basedastronomy using Superconducting Tunnel Junctions(STJs). It has been designed as a technologydemonstrator, aiming to prove the potential of a newgeneration of single photon counting detectors at aground-based telescope. The camera has a field of viewof about 4.0 × 4.0 arcsec^2 and it is based on a6 × 6 array of Ta-Al Josephson junctions, operating atabout 350 mK and individually read-out. For eachdetected photon, the absorption position, the arrivaltime and the corresponding energy are measured. Inthis paper we provide an overview of the cryogenicdetector performance, a description of the S-Cam system and a summary of the results obtained bothduring testing at ESTEC and during the firstobservations at the William Herschel Telescope in La Palma (Canary Islands, Spain). Initialastronomical results on the Crab pulsar are presentedalong with an outlook on future activities. | S-Cam: An Imaging Spectro-Photometer Based on Superconducting Tunnel Junctions | 10.1023/A:1008129522717 |
2000-09-01 | High-Temperature Superconducting Level Gage for Cryogenic Liquid | 10.1023/A:1002847622803 | |
2000-09-01 | Filling and Storage of Cryogenic Propellant Components Cooled Below Boiling Point in Rocket Tanks at Atmospheric Pressure | 10.1023/A:1002820311417 | |
2000-07-01 | We characterized the time-course, intensity of expression and cellular origin of components of the endothelin (ET) system in the rat brain after a standardized neurotrauma (cryogenic lesion of the parietal cortex). ET mRNAs were expressed at sham level after neurotrauma, whereas immunoreactivity for ET-1 was enhanced in glia and endothelium of the lesioned hemisphere and both hippocampi. The number of ET-3 positive mononuclear cells in the lesion perimeter increased starting at 24h after injury. At 48h after neurotrauma, ET-receptor immunoreactivity was increased in astrocytes. In basilar artery endothelium, ET_B-immunoreactivity was reduced at 48h to 72h recovering at 7 days whereas ET_A-receptor and ET-peptide immunoreactivities were not altered. In summary, neurotrauma leads to a multicellular stimulation of endothelins in the brain along with a delayed selective loss of vascular ET_B-receptors. These changes seem to be posttranscriptional and cell type specific. They favor vasoconstriction increasing the risk of late vasospasm and ischemia. | Differential Glial and Vascular Expression of Endothelins and Their Receptors in Rat Brain after Neurotrauma | 10.1023/A:1007552408463 |
2000-07-01 | Tetraethylammonium perfluorooctyl sulfonate (TEAFOS; critical micelle concentration, 1 mM), which forms a threadlike micelle in its pure solution, was adopted to study the structure of salted-out, solubilized micelles and microemulsions by cryogenic transmission electron microscopy. The concentration of the surfactant was kept constant at 60 mM. The micelle solution salted out with LiNO_3 provided a surfactant phase in the presence of a clear interface. The surfactant phase was studded, being formed of homogeneously dispersed spherical micelles, and had no obvious threadlike forms. The micelles, which solubilized the maximum amount of perfluorinated oil, were spherical and had the same size as isolated spherical micelles in pure TEAFOS solution. The microemulsions were formed in the presence of perfluorinated alcohol as cosurfactant and the particles were rotund even when the concentration of the perfluorinated oil was equivalent to that for solubilization and the sizes increased with increasing oil content. The difference in size between the solubilized micelles and microemulsions with the same amount of oil suggested that the oil molecules had been solubilized between palisades of perfluorinated alkyl chains in the micelles and had dissolved in the cores of the microemulsions. | Structure of salted-out, solubilized micelles and microemulsions on the perfluorinated anionic surfactant tetraethylammonium perfluorooctyl sulfonate studied by cryogenic transmission electron microscopy | 10.1007/s003960000293 |
2000-04-01 | The viability of two strains of Lentinula edodes and two of L. boryana under cryogenic storage during 1 week has been studied from the evaluation of five contact periods (1, 1.5, 2, 3 and 5 h) of the cryoprotector, glycerol 10% (v/v), with the mycelium. On average, 99.25% of samples were recovered, 1.5 h being the best contact period. Afterwards, samples of the strains, before and after the cryogenic process, were cultivated at a pilot plant using a mix of Carpinus carolineana sawdust, rice bran and sorghum grains as substrate. The evaluation parameters were: days of incubation, primordia initiation, number of flushes, fruiting body sizes and biological efficiency (EB). Only L. edodes developed carpophores. On average, 3–4 flushes were obtained, which reached EB of 67.1 ± 30.7 to 74.7 ± 24.5 with no statistical differences detected between the yields. The majority of fructification sizes ranged from 5 to 14.9 cm. Morphological differences between the samples before and after the treatment were not observed. | Viability and mushroom production of Lentinula edodes and L. boryana strains (Fungi: Basidiomycetes) after cryogenic storage of spawn stocks | 10.1023/A:1008979202575 |
2000-04-01 | A gas mixture containing ppbv concentrations of volatile chlorinated and aromatic hydrocarbons was prepared in helium, nitrogen, or argon in a plastic (Nalophan) bag, in which it was found the mixture could be safely stored for several days. Samples of the mixture were subsequently analyzed by gas chromatography after direct cryotrapping in an empty metal U-tube. The cooling medium used was liquid nitrogen, liquid argon, or a dry ice-acetone slurry (197 K). The efficiency of cryotrapping in liquid nitrogen was over 90% when the aromatic hydrocarbon mixture was prepared in the helium matrix, but between 50 and 70% when it was prepared in nitrogen or argon, the recovery from the argon matrix being somewhat higher. The poor recovery in nitrogen at 77 K and argon at 87 K was explained by the reduced rate of diffusion to the wall owing to mist or aerosol formation. At 197 K condensation was negligible if the partial pressures were lower than the saturated vapor pressures. | Matrix effect in the cryotrapping of gas samples in the ppbv range | 10.1007/BF02490485 |
2000-02-01 | High-pressure pumps for cryogenic liquids: Problems and prospects | 10.1007/BF02464737 | |
2000-01-01 | Ti-5Al-2.5Sn extra-low-interstitial (ELI) alloy is widely used as a structural material in cryogenic engineering because of its outstanding mechanical behaviour, especially at low temperatures. ELI Ti-5Al-2.5Sn exhibits unstable plastic flow (load drops) at very low temperatures (below 40K). The influence of temperature and sequential straining on load drops in tensile stress-strain curves are investigated. Multi-necking is detected in the static tensile experiments of ELI Ti-5Al-2.5Sn. Cryogenic temperature is of crucial importance to the occurrence of this phenomenon. Transmission electron microscopy (TEM) results are presented to discuss the possible reason of multi-necking. In additional, an optical method is used to gauge the geometry of multi-necking specimens. | Temperature Dependence of Unstable Plastic Flow and Multi-Necking in ELI Ti-5Al-2.5Sn Alloy | 10.1007/978-1-4615-4293-3_12 |
2000-01-01 | We have tackled with the improvement of the superconducting magnetic bearings and manufactured the newly developed facility which has possessed the cooling device with cryogenic refrigerator and the driving device for the completely floating rotational elements, and can be utilized to research and development for various type of the bearings. We have confirmed the small loss of 0.26W about the axial gap thrust bearing of 238mm diameter at speed of 3000 min^2212;1 and load of 281N. We introduce the test facility and report the test results. | Investigation of Characteristics of Axial Gap Type Superconducting Magnetic Bearing for 1kWh Flywheel | 10.1007/978-4-431-66877-0_235 |
2000-01-01 | High strength polymer fiber reinforced plastics (ZFRPs) have a remarkable characteristic of a negative thermal expansion coefficient, that is, ZFRPs expand during cooling down from room temperature to cryogenic temperature. Hence, it is expected that ZFRPs are suitable for bobbins of superconducting magnets from a view point of stability against mechanical disturbance due to abrupt conductor motions. A frictional property of contacting surfaces between magnet bobbins and superconductors is one of important parameters for characterizing the stability of the superconducting magnets. We have systematically analyzed the frictional properties on surfaces of ZFRPs. A contacting material of ZFRP is CuNi assuming AC superconducting magnets. Contacting forces between CuNi and ZFRP are 10 and 26 N. The frictional tests were performed at liquid helium temperature, liquid nitrogen temperature, and room temperature. It was experimentally obtained that the frictional coefficients on the surfaces of ZFRPs were much lower than those of GFRPs (glass fiber reinforced plastics). We also observed the surfaces of ZFRPs after the tests by scanning electron microscopy. The microscopically analyzed results were consistent with the measured data of the frictional coefficients. | Frictional Properties on Surfaces of High Strength Polymer Fiber Reinforced Plastics | 10.1007/978-1-4615-4293-3_16 |
2000-01-01 | In the Accelerator Production of Tritium (APT) project, a one-kilometer-long linear accelerator (linac) is used as part of a plant that will provide tritium for national defense purposes. The accelerator consists of a low-energy (LE) normally conductive, radiofrequency (rf) linac and a high-energy (HE) superconducting rf linac. The APT cryogenic system will supply cryogenic helium fluids to maintain the HE linac superconducting rf cavities at the required operating temperatures and pressures. Presently under continuing development, the cryogenic system was originally intended to provide 27 kW of refrigeration at 2.15 K and 0.046 mbar to cool the superconducting niobium rf cavities, and 82 kW of 4.5 K refrigeration for thermal shielding. Program redirection has led to a system design that supports 15 kW at 2.15 K and 66 kW at 4 K to 50 K, with the potential for upgrading to higher linac energies and refrigeration capacity. The cryogenic system will consist of multiple interconnected 2.15 K refrigerators (split into 4 K and 2 K coldboxes) with required compressors, gas and liquid storage, and a vacuum-jacketed cryogen distribution system. Each 2 K cold box will employ 4 stages of cold compressors in series. This will be the first industrial application of large, multiple cold compressor systems operated in parallel. System requirements, current design direction, and potential design options are presented. | APT Cryogenic System | 10.1007/978-1-4615-4215-5_46 |
2000-01-01 | A high-T_c SQUID-based magnetometer system for measuring fetal heart activity in standard clinical environments is the goal of the so-called FHARMON project. To lower the threshold for the application of this fetal heart monitor, it should be low-cost and, moreover, simple to operate. It is, therefore, advantageous to replace the liquid cryogen bath by a closed-cycle refrigerator. In this paper the requirements with respect to the cryogenic system are discussed for this specific application. These include operating temperature (55–80 K), temperature stability (<0.5 K drift in 10 hours), cooling power (<0.5 W), mechanical vibrations, electromagnetic interference and costs (<$US 5000). Next to the requirements, the paper also reviews the most relevant options for the realization of the cryogenic system. In this respect two categories are distinguished: systems incorporating coolers with ‘noisy’ cold heads (e.g. GM and Stirling) versus those using coolers with a low-noise cold head (e.g. pulse tube and JT) requiring respectively long and short thermal interfaces. | Cryogenic Aspects of a Fetal Heart Monitor Based on High-Tc Squids | 10.1007/978-1-4615-4215-5_85 |
2000-01-01 | It may happen, sometime, that the reader spends his or her well deserved holidays in the beautiful country of Greece and, sitting on a typically unstable chair in one of the nice taverns, one may ask for “kryo nero”. It may take a while, but you will get a nice jug filled to the top with icy cold water. Indeed, “cryo” means “cold”, and cooling was already known as a means to improve the quality of life in the early times The Egyptians put wet cloths over their foods, and placed them in the sun, so that the heat associated with the evaporation of the water cooled their food and drinks The Romans cooled their foods with ice blocks that were taken from Alpine regions and were stored underground in vaults insulated with straw. Our forefathers in Europe cut ice blocks out of rivers or shipped ice from Norway or Canada. In special ice factories rods of ice were made to be used for instance in butcheries and breweries. | Cryogenic Systems for Superconducting Devices | 10.1007/978-94-017-0752-7_13 |
2000-01-01 | The aim of this study was to investigate fatigue crack growth resistance of a new superlight high-strength Al-Cu-Li alloy at 293 and 77K and to assess the possibility of its application in cryogenic aerospace structures. It is found that at temperatures lowering to 77K fatigue crack growth resistance is essentially dependent on the sample orientation with respect to the sheet rolling direction and on the amplitude of the stress intensity factor. The correlation of the kinetic fatigue failure diagrams, fracture macromorphology and the specific structure-phase alloy state has been analyzed. | Super Light Alloy Al-Cu-Li-Fatigue Crack Growth Resistance at Temperatures 293 and 77K | 10.1007/978-1-4615-4293-3_14 |
2000-01-01 | A long lifetime, low cost, vapor-shielded liquid neon and liquid helium cryostat and an adiabatic demagnetization refrigerator have been developed for cooling a bolometric radiometer to 0.1 K for mm and sub-mm observations of the cosmic microwave background. This is the first phase of a development effort for a very long hold time system for use in NASA’s 100 Day Ultra Long Duration Balloon Project. This type of system has additional applications in sub-orbital and ground-based research in millimeter, sub-millimeter, infrared, and x-ray astrophysics. A detailed description of the design, analysis, and performance of the system is presented and plans for follow-up design improvements are discussed. | A Long Lifetime Balloon-Borne Cryostat and Magnetic Refrigerator | 10.1007/978-1-4615-4215-5_87 |
2000-01-01 | The strong magnetic field of the interventional magnetic resonance imaging (IMRI) challenges the designer of surgical and particularly of cryosurgical devices. It strongly interferes with electronic, electromechanical and magnetic media. The proposed solution incorporates an argon based Joule-Thomson cryosurgical machine. The entire main frame, including control, monitoring and pressure vessels, is installed outside the MRI affected chamber, remaining totally out of the influence of the magnetic field. Gas supply tubing provides argon to a panel close to the site of surgery or on the magnet frame itself. It includes ports for five cryoprobes and their control enabling autonomous operation, sufficiently handy and close to the surgical site. In addition, the view of the outer main frame monitor that displays the parameters of cryosurgical treatment is transmitted to the MRI display monitor. So far, successful experience is accumulated on about ten IMRI medical center stations. | MRI Compatible Cryosurgical Machine | 10.1007/978-1-4615-4215-5_121 |
2000-01-01 | The linear viscoelastic parameters — storage shear modulus and loss factor — have been studied between 4.2K and 293K by a torsion pendulum on various fibres (carbon, fibreglass and Kevlar) with different polymeric matrices (epoxies and PEEK) in the unidirectional (UD) composites. The off-axis properties in UD carbon AS4/PEEK and fibreglass/epoxy have been investigated at 0, 30, 45, 60 and 90 degrees on the fibre directions. The influence of low-temperature (the second and the third) glass transitions on loss factors is considered in comparison with the matrix results. The contribution of fibre-matrix interface on loss factor is also discussed at very low temperatures, below 100K. | Viscoelastic Behaviour of Unidirectional Fibre Composites at Low Temperatures | 10.1007/978-1-4615-4293-3_24 |
2000-01-01 | The cooling capacity for the superconducting magnets in the Large Hadron Collider (LHC) at the European Laboratory for Particle Physics, CERN will be provided by eight helium refrigerators serving the eight 3.3 km long machine sectors. Of these eight refrigerators, four are already existing and are currently used for the Large Electron Positron Collider (LEP) project. These existing refrigerators have to be modified to fulfil the requirements for the LHC. Four new refrigerators providing cooling capacity down to 4.5 K will be added. All eight 4.5 K refrigerators will be connected to 1.8 K cooling stages. This presentation recalls the cryogenic architecture of the LHC, the constraints in process design resulting from it and from the desired capacity for steady state and transient operation. It then describes how these requirements were expressed in the technical specification for the four new 4.5 K refrigerators to be delivered between the years 2000 and 2002. | Specification of Four New Large 4.5 K Helium Refrigerators for the LHC | 10.1007/978-1-4615-4215-5_40 |
2000-01-01 | In large cryogenic storage systems, the level of cryogenic fluids such as liquid nitrogen, liquid oxygen, etc., are usually monitored using capacitance type indicators. They are both heavy and inaccurate. We report here the development of discrete array type liquid level indicators. A special class of analog multiplexer IC, which operates at cryogenic temperatures, is used in the unit. Operating it at liquid helium temperature and switching the channels one million times without any failure tested the reliable operation of the IC at cryogenic temperature. The system is capable of detecting the liquid level of any cryogen. Only a software tuning is required for operation with each fluid. The developed unit has an active length of 400 mm and six regions with sensitivities ranging from ± 5 mm to ± 0.5 mm. Redundancy of level measurement is achieved through software. The interaction of the system that has 138 sensors to ambient electronics is through only 15 wires. The integrated unit has been cycled several times between room temperature and 77 K. | Development of Discrete Array Type Liquid Level Indicator for Cryogenic Fluids | 10.1007/978-1-4615-4215-5_108 |
2000-01-01 | We have studied the microstructures and mechanical properties of 14.5, 15.5 and 16.5 mol%CeO_2-ZrO_2 ceramics which were aimed to obtain toughening at low temperatures. The results indicated that there were over 50% increases in fracture toughness and strength at 4.2K. The enhancements of both parameters are due to the stress-induced tetragonal to monoclinic transformation at low temperatures. TEM observation revealed such a process covering the crack formation due to dislocation piling up at a grain boundary and a frontal zone shape ahead of a crack tip at the very beginning of transformation. According to observed transformation zone shape, associating the considerations of variable critical mean stress and variable volume fraction of the monoclinic phase that transformed from tetragonal phase in the zone near the crack tip, a new stress-induced toughening formulae was deduced by using the method of energy balance integral, and the calculated results on fracture toughness show to be quantitatively consistent to the experiments. In addition to stressinduced transformation toughening, other toughening contributions have also been discussed in this paper. | Microstructure and Toughening of Ce-TZP Ceramics at Low Temperatures | 10.1007/978-1-4615-4293-3_33 |
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