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Lilian Samaniego Lilian Graciela Samaniego González (born 25 February 1965) is a Paraguayan pharmaceutical chemist and politician of the National Republican Association-Colorado Party (ANR-PC). She has been a member of the Senate of Paraguay since 2004. was born on 25 February 1965, in San Vicente, a neighborhood of Asunción, to parents Ignacio E. Samaniego and Elisa González de Samaniego, recognized leaders of the ANR. She has two brothers – , who was mayor of Asunción from 2010 to 2015, and Gustavo. She completed her primary and secondary studies at the Cristo Rey de Asunción School, from which she graduated as a Bachelor of Science and Letters in 1983. She entered the Universidad Nacional de Asunción, and in 1987 she graduated from the Faculty of Chemical Sciences with the degree of pharmaceutical chemist. She completed postgraduate studies in the United States, Europe, and the Mercosur countries. On 14 July 1998, while Samaniego was working as head of the healthcare campus of the (IPS), police arrested several people in connection with a cache of prescription medications seized in Asunción. These were marked "exclusive use of IPS" and valued at approximately 800 million guaraní (US$290,000). Samaniego was investigated as a possible conspirator, and lost her position, but charges against her were later dropped. About one year later, she was re-appointed as head of the pharmaceutical unit by IPS chief Darío Filártiga, who was also a political advisor to Horacio Cartes | https://en.wikipedia.org/wiki?curid=62161815 |
Lilian Samaniego joined the Colorado Party on 24 March 1982, where she was very active, holding various positions as a delegate, proxy, political secretary of the governing board, and president of the women's central commission. She has been part of some of the party's internal movements, such as the United Colorado Movement, the Republican Participation Movement, and the Colorado Vanguard Movement. She was expelled from the latter in 2008 due to dissatisfaction with a deal she had reached with former President Nicanor Duarte. Samaniego was elected first vice president of the ANR by more than two thirds of the governing board, and immediately assumed the interim presidency of the party on 16 September 2008. She took over in the midst of an internal crisis, after a major loss in that year's general election, where opposition candidate Fernando Lugo triumphed and ended more than 60 years of Colorado governments. She led her party to a resurgence in the 2010 municipal elections, leaving it well positioned to return to power in 2013 with the election of Horacio Cartes. She was ratified in her position as president in the internal elections of 13 March 2011, becoming the first woman to be elected to the position in the party's 124-year history. Samaniego was elected as alternate senator for Asunción in 2003, and took over as titular senator in 2004. She was reelected in 2008, 2013, and 2018. She is president of the body's Equity and Gender Commission. | https://en.wikipedia.org/wiki?curid=62161815 |
Lynda Soderholm is a physical chemist at the U.S. Department of Energy’s (DOE) Argonne National Laboratory with a specialty in f-block elements. She is a senior scientist and the lead of the Actinide, Geochemistry & Separation Sciences Theme within Argonne's Chemical Sciences and Engineering Division. Her specific role is the Separation Science group leader within Heavy Element Chemistry and Separation Science (HESS), directing basic research focused on low-energy methods for isolating lanthanide and actinide elements from complex mixtures. She has made fundamental contributions to understanding f-block chemistry and characterizing f-block elements. Soderholm became a Fellow of the American Association for the Advancement of Science (AAAS) in 2013, and is also an Argonne Distinguished Fellow. Soderholm was awarded her PhD in 1982 by McMaster University. Her dissertation focused on characterizing the structural and magnetic properties of a series of ternary f-ion oxides. After graduating, she became a NATO postdoctoral fellow at the Centre national de la recherche scientifique in France from 1982 until 1985. She then began her career at Argonne as a postdoctoral fellow in 1985, and was promoted to staff scientist the same year. Over several years, she moved up the ranks, becoming a senior chemist in 2001. She was also an adjunct professor at the University of Notre Dame from 2003 until 2007 | https://en.wikipedia.org/wiki?curid=62162151 |
Lynda Soderholm Early in her career, Soderholm focused on the characterizing the magnetic and electronic behavior of compounds containing f-ions (lanthanides and actinides) with a focus on high-T materials, compounds that are superconducting under usually high temperatures. She was part of the research group that first determined the structure of YBaCuO. Their discovery formed the foundation for the further developments in the broad field of superconductivity. Continuing her interest in the f-elements, Soderholm shifted her focus from solid-state materials to nanoparticles and solutions, taking advantage of advances in X-ray structural probes made available by synchrotron facilities. Building on her earlier work using neutron scattering, her team became the first to discover that plutonium exists in solution as tiny, well-defined nanoparticles. This work solved a longstanding problem in understanding transport of plutonium in the environment and resulted in the development of a new, patented approach to separating plutonium during nuclear reprocessing. Soderholm’s more recent projects use machine learning to understand the influence of complex molecular structuring in solutions, in connection with low-energy processes for separation of f-block elements from complex mixtures. | https://en.wikipedia.org/wiki?curid=62162151 |
Bimetallic nanoparticle A bimetallic nanoparticle is a combination of two different metals that exhibit several new and improved properties. Bimetallic nano materials can be in the form of alloys, core-shell, or contact aggregate. Due to their novel properties, they have gained a lot of attention among the scientific and industrial communities. When used as catalysts, they show improved activity as compared to their monometallic counterparts. They are cost-effective, stable alternatives that exhibit high activity and selectivity. Hence a lot of effort has been put into the advancement of these catalysts. The combination or the type of metals present, how they are combined, and their size determines their properties. Since two distinct metals are combined, optimizing their properties through manipulation is possible. There is a lot of flexibility in designing the bimetallic nanoparticle for specific applications. There are several techniques developed for their synthesis and accurate characterization. Improved electronic properties that arise due to bi-metallization is the most important among the novel properties. Electronic effects involve charge transfer or orbital hybridization between the constituent metals. Structural changes can result from alloy formation. The chemical and environmental parameters during their synthesis play a role in determining their structural properties.The difference in the reduction rates of the different metal precursors decides the end structural properties of the nanomaterial | https://en.wikipedia.org/wiki?curid=62173649 |
Bimetallic nanoparticle The synthesis of bimetallic nanoparticles can be done using co-reduction, successive reduction, reduction of complexes containing both the metals and electrochemical methods. Co-reduction and successive reduction methods are the most popular preparative techniques. The co-reduction method is similar to that of the reduction method used in the synthesis of monometallic nanoparticles. The difference is that for bimetallic nanoparticle synthesis two metal precursors will be used instead of one. The two precursors along with the stabilizing agent are completely dissolved in a suitable solvent. The metals will be present in their ionic states. To convert them into their zerovalent states a reducing agent is added. The light transition metals have lower reduction potential which means that they are rarer to undergo reduction. These light transition metals when present in their zerovalent states tend to undergo oxidation very quickly and therefore are unstable. Since these metals are very important in the field of catalysis, several methods to stabilize them are sought after. In the successive reduction method, the two precursors are added one after the other. This method generally leads to the formation of core-shell bimetallic nanoparticles. The precursor of the metal that has to form the core is added along with the stabilizing agent first. This is followed by the reducing agent. Once the complete reduction of the first metal is ensured, the second metal precursor is added | https://en.wikipedia.org/wiki?curid=62173649 |
Bimetallic nanoparticle The second metal ion gets adsorbed on the nanoparticle surface and gets reduced. This results in the core-shell structure of the bimetallic nanoparticle. Reduction of bimetallic complexes A complex containing both the metals to be present in the bimetallic nanoparticle is taken as the precursor. The aqueous solution of these complexes in different concentrations is taken in a quartz vessel and reduced using a photoreactor. Polyvinylpyrrolidone can be used as a stabilizer. The size and composition of the nanoparticles vary with the concentration of the aqueous solution. The composition of the nanoparticles can be analyzed using EDX studies. In chemical methods, the metal ions are reduced to their zerovalent states using a reducing agent. In the electrochemical process, bulk metal is converted into metal atoms. The size of the particle synthesized using this method can be controlled by manipulating the current density. There are two anodes made up of the constituent bulk metal and a platinum metal plate is used as the cathode. The stabilizing agent is mixed with the electrolyte. When current is passed ions of the metals are formed at the anode and are reduced by the electrons generated in the platinum electrode. The major attractions of this method are its cost-effectiveness, high yield, ease of isolation, and the ability to control the composition of metal simply through variation of current density | https://en.wikipedia.org/wiki?curid=62173649 |
Bimetallic nanoparticle In this type of arrangement, the more expensive or catalytically important metal atom is individually arranged over the comparatively cheaper metal which is catalytically less active. The precious metal atom will be surrounded by the less expensive metal atoms. As they are present on the surface they are highly accessible for catalytic reactions. Being surrounded by the less expensive metal also alters its electronic properties, this, in turn, improves its catalytic property. As the metal atoms are fixed on the surface individually, the synthesis of crown jewel structure is difficult. It can be achieved through chemical vapor deposition (CVD). The metal is atomized using an electron beam evaporator and the whole process was carried out in an ultra-high vacuum. The metal gets diffused and deposits at different points on the less expensive metal surface. Their distribution can be determined by controlling the metal flux in a reproducible manner. Another alternative is the solution state method. Control of size and distribution is more complicated when using this method as opposed to CVD. The structures have a very high surface to volume ratios and porosity. This material is multifunctional owing to its unique structure. The void can be used to encapsulate various multifunctional nanomaterial or even as a nanoreactor. Their shells can also be functionalized. These materials are better catalysts as they are cheaper, less dense and the material is also saved | https://en.wikipedia.org/wiki?curid=62173649 |
Bimetallic nanoparticle They can be synthesized by using already prepared metal nanoparticles as sacrificial templates. This takes place through a galvanic replacement reaction in which a metal nanoparticle comes in contact with a different metal of higher reduction potential gets replaced. The diffusion process and direction of the reaction can be controlled by changing the chemical environment. As catalysis is carried out on the nanoparticle surface, the atoms at the center are wasted. This becomes more important when expensive metals are used as catalysts. To reduce the cost of the catalysts an inexpensive metal is made the core and the catalytically active metal is taken as the shell. This is achieved by first reducing the core metal followed by nucleation of the shell metal around it. The core metal also electronically modifies the shell and thereby improves catalytic activity. They can be synthesized by using a one-pot co-reduction method. Two metal precursors are added simultaneously. One of them will reduce first due to the difference in the reduction potentials of the different metal ions. This metal will form the core. The pre-formed nanoparticle acts as the seed required for the nucleation of the second metal around it. These structures can be characterized using TEM imaging. The shape and size can be manipulated by varying the different parameters. It is possible to synthesize a more complex multiwalled nanostructure, but it will require better control over the parameters | https://en.wikipedia.org/wiki?curid=62173649 |
Bimetallic nanoparticle The two different metals present are homogeneously arranged. Due to the variation in their standard reduction potentials the metals tend to nucleate separately and form heterostructures or core-shell. Synthesizing alloyed bimetallic nanoparticles require control over reaction kinetics. Using a reducing agent strong enough to reduce both the metal ions is one option. Sodium borohydride is one such reducing agent. Another option is the selection of appropriate counter ion or surfactant. The redox potentials of the metals are adjusted in such a way as to obtain simultaneous reduction through specific coordination or adsorption. The addition of a metal ion that facilitates alloy formation is the third method. A gas-phase synthesis technique is also possible in which the atoms are first brought to their atomic states. But this method will require complicated instrumentation. | https://en.wikipedia.org/wiki?curid=62173649 |
Hanoch Senderowitz (born 1963) () is an Israeli chemist specializing in the fields of Computational Chemistry, Molecular modelling, Computer-Aided Drug Design, and Chemoinformatics. received his Ph.D. in 1993 from Tel Aviv University under the supervision of Prof. Benzion Fuchs. He then spent four years as a Post Doctorate Fulbright fellow at Columbia University, working with Prof. W. Clark Still. After returning to Israel in 1997, he joined the pharmaceutical industry, working first at Peptor Ltd. for six years and then at Epix Pharmaceuticals until 2008. In 2009, he joined Bar Ilan University as an associate professor at the Department of Chemistry leading the molecular modeling, computer-aided drug design and chemoinformatics lab, where he currently holds the position of the Head of the Department. Senderowitz's research focuses on the developing and application of new computational methods to design compounds (i.e., drugs, materials) with improved properties. This design strategy is multi-disciplinary in nature and consists of various levels of theory, different computational techniques, and different machine learning algorithms. Senderowitz is known for the following areas of research: (1) Research on CFTR (Cystic fibrosis transmembrane conductance regulator), the main protein implicated in the genetic disease Cystic fibrosis, both at the level of the full-length protein and of its domains | https://en.wikipedia.org/wiki?curid=62175747 |
Hanoch Senderowitz His basic research focuses on understanding the dynamics of the protein and on the mechanism of action of deleterious, rescuing and stabilizing perturbations to its domains, while his translation research focuses on CFTR as a target for drug discovery. (2) Research on chemoinformatics and materials informatics, focusing on the development of new machine learning algorithms as well as on their application in various areas, for example, for the analysis and development of solar cells with improved photovoltaic properties. (3) Research on computational agriculture including plant disease biocontrol studying anti-bacterial peptides expressed on virus nanoparticles, design of new pesticides in the form of small molecules that inhibits the bacterial quorum sensing machinery, and the design of new sustainable pesticides in the form of peptide aptamers and small molecules that would interfere with cell building enzymes of bacteria. (4) Research on different drug discovery projects, in particular in the field of neurodegenerative diseases such as ALS, Alzheimer, familial dysautonomia and the vanishing white material disease as well as diabetes, and calcification-related diseases and autoimmune disease. He has over 90 peer-reviewed articles, and has contributed to various book chapters. | https://en.wikipedia.org/wiki?curid=62175747 |
Spin echo small angle neutron scattering (SESANS) measures structures from around 20 to 2000nm in size. The information is presented as a real-space (similar to g(r)) as opposed to a reciprocal space (q(r)) mapping. The this can simplify the interpretation for some systems. SESANS is useful for studying processes that occur over relatively long time scales, as data collection is often slow, but large length scales. Aggregation of colloids, block copolymer micelles, Stöber silica particles being a prime examples. The technique offers some advantages over SANS, but there are fewer SESANS instruments available than SANS instruments. Facilities for SESANS exist at TUDelft (Netherlands) and Rutherford Appleton Laboratory (UK). | https://en.wikipedia.org/wiki?curid=62181250 |
Robert C. Armstrong Robert Calvin Armstrong is director of the Massachusetts Institute of Technology Energy Initiative. He has been a member of the MIT faculty since 1973, and served as head of the Department of Chemical Engineering from 1996 to 2007. He was elected a member of the National Academy of Engineering in 2008. | https://en.wikipedia.org/wiki?curid=62181814 |
Jürgen Rödel (born September 17, 1958 in Hof) is a German materials scientist and professor of non-metallic inorganic materials at the Technische Universität Darmstadt. He is particularly well known for his fundamental and pioneering work on the mechanical and functional properties of ceramics. This includes his research work on the sintering behaviour of ceramics and the development of lead-free piezoceramics. Until then, lead-free piezo materials were considered impossible. Through meticulous research, he found the first lead-free systems with "Giant" elongation. In 2008, he received the Gottfried Wilhelm Leibniz Prize, the highest award for German researchers, for his contributions to the development of ferroelectric functional ceramics, new lead-free piezoelectric ceramics and novel gradient materials. From 1977 to 1983, Rödel studied materials science at the University of Erlangen and ceramics at the University of Leeds. Rödel received his diploma in materials science from the University of Erlangen. In 1988, he received his Ph.D. in materials science from the University of California, Berkeley. In 1992, he habilitated in materials science at the TU Hamburg-Harburg. Since 1994 he has been professor of non-metallic inorganic materials at the Technische Universität Darmstadt. In 2019, has acquired the research grant Reinhart-Koselleck project funded by the German Research Foundation (DFG). It was the first time for the Technische Universität Darmstadt that the grant was brought to the university | https://en.wikipedia.org/wiki?curid=62189156 |
Jürgen Rödel With the support he is currently working on improving ceramics by disrupting their atomic structure. His team is concentrating on a type of crystal defect that, although trivial for metals, has so far seemed unthinkable for hard ceramics. The mechanical deformation of ceramics takes place under controlled pressure and temperature. | https://en.wikipedia.org/wiki?curid=62189156 |
Robert Kennedy (chemist) Robert (Bob) Kennedy (born 1962) is an American chemist specializing in bioanalytical chemistry including liquid chromatography, capillary electrophoresis, and microfluidics. He is currently the Hobart H. Willard Distinguished University Professor of Chemistry and the Chair of the Department of Chemistry at the University of Michigan. He holds joint appointments with the Department of Pharmacology and Department Macromolecular Science and Engineering. Kennedy is an Associate Editor of Analytical Chemistry. Kennedy was born on November 11, 1962, in Sault Ste. Marie, Michigan. He earned a Bachelor of Science degree in Chemistry at the University of Florida in 1984 and a Ph.D. from the University of North Carolina-Chapel Hill (UNC) in 1988 while working under James Jorgenson. He was an NSF post-doctoral fellow at UNC from 1989-1991 with R. Mark Wightman. Kennedy became a professor of chemistry at the University of Florida in 1991. After 11 years, he moved to the University of Michigan. He has graduated approximately 70 graduate students. Kennedy’s research focuses on developing analytical instrumentation and methods that can help solve biological problems. He is considered a leader in the field of analytical chemistry, and an expert in endocrinology, neurochemistry, and high-throughput analysis. Major contributions to analytical chemistry include affinity probe capillary electrophoresis, in vivo neurochemical measurements, and ultra-high pressure liquid chromatography | https://en.wikipedia.org/wiki?curid=62194268 |
Robert Kennedy (chemist) He has been an Lilly Analytical Research Fellow, Alfred P. Sloan Fellow, NSF Presidential Faculty Fellow, and AAAS Fellow. | https://en.wikipedia.org/wiki?curid=62194268 |
Sachdev-Ye-Kitaev model In condensed matter physics and black hole physics, the Sachdev-Ye-Kitaev (SYK) model commonly known as SYK model is an exactly solvable model initially proposed by Subir Sachdev and his graduate student Jinwu Ye and later modified by Alexei Kitaev to the present commonly used form. The model is believed to bring insights into the understanding of strongly correlated materials and it also has a close relation with the discrete model of AdS/CFT, and Fermionic code. Let formula_1 be an integer and formula_2 and even integer such that formula_3, consider a set of Majorana Fermions formula_4which are Fermion operators satisfy conditions: (1) Hermitian formula_5; (2) Clifford relation formula_6. Choosing a random variable formula_7 such that the expectation satisfy: (1) formula_8; and (2) formula_9, Then the SYK model is defined as formula_10. Note that sometimes, an extra normalization factor will be added. The more famous model is when formula_11, then the model becomes formula_12, notice that here the factor formula_13 is added for coincidence with the usually used form. | https://en.wikipedia.org/wiki?curid=62223541 |
Desnitro-imidacloprid is a metabolite of the insecticide imidacloprid, a very common insecticide and the most important member of the class of insecticides called neonicotinoids, the only significant new class of insecticides to be developed between 1970 and 2000. While imidacloprid has proved highly selective against insects, the desnitro- version is highly toxic to mammals, due to its agonist action at the alpha4beta2 nicotinic acetylcholine receptor (nAChR) in the mammalian brain, at least as demonstrated in experiments involving mice. | https://en.wikipedia.org/wiki?curid=62226149 |
Organic Reactions is a peer-reviewed book series that was established in 1942. It publishes detailed descriptions of useful organic reactions. Each article (called a chapter) is an invited review of the primary source material for the given reaction, and is written under tight editorial control, making it a secondary to tertiarylevel source. Each chapter explores the practical and theoretical aspects of the reaction, including its selectivity and reproducibility. The longest chapter runs to 1,303 pages. While individual articles are not open access, the journal's wiki maintains a repository of summaries of reactions. The series is abstracted and indexed in Scopus. Prior to World War II, the center of organic chemistry research and industrial production was Germany. Students interested in pursuing a career in organic chemistry needed to learn German to read articles and textbooks, and often went to graduate school in Germany. When the war broke out, an effort to jumpstart a native US organic chemical industry and academic network was initiated. As part of this effort, the journal was launched. The first volume was published in 1942, with Roger Adams as editor-in-chief. In the early years a volume would come out every two years or so, but the pace of publishing has accelerated, with volume 100 due out in 2019 or 2020. | https://en.wikipedia.org/wiki?curid=62229444 |
List of crimes involving a silicone mask Realistic silicone masks have been used in crimes throughout the world. In China, criminals can obtain silicone masks cheaply from the internet and have used them for criminal activities. Silicone masks have been used as a disguise to conceal identity to perpetrate crimes. | https://en.wikipedia.org/wiki?curid=62230071 |
C7H9N2O The molecular formula CHNO may refer to: | https://en.wikipedia.org/wiki?curid=62237589 |
Methylnicotinamide may refer to: | https://en.wikipedia.org/wiki?curid=62237624 |
Phosphinous acids are usually organophosphorus compounds with the formula RPOH. They are pyramidal in structure. Phosphorus is in the oxidation state III. Most phosphinous acids rapidly convert to the corresponding phosphine oxide, which are tetrahedral and are assigned oxidation state V. Phosphorous acid OP(OH)H is an example of an phosphinous acid lacking organic substituents. Only one example is known, bis(trifluoromethyl)phosphinous acid, (CF)POH. It is prepared in several steps from phosphorus trichloride (Et = ethyl): With the lone exception of the bis(trifluoromethyl) derivative, the dominant reaction of phosphinous acids is tautomerization: Even the pentafluorophenyl compound P(CF)OH is unstable with respect to the phosphine oxide. Although phosphinous acids are rare, their P-bonded coordination complexes are well established, e.g. Mo(CO)P(OH). Tertiary phosphine oxides, compounds with the formula RPO cannot tautomerize. The situation is different for the secondary and primary phosphine oxides, with the respective formulae R(H)PO and R(H)PO. | https://en.wikipedia.org/wiki?curid=62252965 |
Hughes–Ingold symbol A describes various details of the reaction mechanism and overall result of a chemical reaction. For example, an S2 reaction is a substitution reaction ("S") by a nucleophilic process ("N") that is bimolecular ("2" molecular entities involved) in its rate-determining step. By contrast, an E2 reaction is an elimination reaction, an S2 reaction involves electrophilic substitution, and an S1 reaction is unimolecular. The system is named for British chemists Edward D. Hughes and Christopher Kelk Ingold. | https://en.wikipedia.org/wiki?curid=62256831 |
Zinc azide (Zn(N)) is an inorganic compound composed of zinc and azide. It is a white, explosive solid. It is a coordination polymer, which crystallizes in three polymorphs, all of which feature tetrahedral Zinc centers and bridging azide ligands. They are prepared by the protonolysis of diethyl zinc with hydrazoic acid: | https://en.wikipedia.org/wiki?curid=62257007 |
Jack D. Keene (born June 22, 1947, Jacksonville, Florida) is a James B. Duke Professor of Molecular Genetics and Microbiology at Duke University. Keene studies the regulation of RNA and the mechanisms of RNA-protein interactions. He identified RNA recognition motif (RRM) proteins, which are the largest family of RNA-binding proteins. He isolated the first human autoimmune antigen. He formalized the posttranscriptional operon and regulon (PTRO) model to describe global gene regulation, and proposed the RNA regulon hypothesis to better understand post-transcriptional regulation of mRNAs encoding proteins. Keene introduced the RIP (ribonucleoprotein immunoprecipitation) protocol for isolating specific mRNPs, which has become a tool for the mapping of mRNA targets of specific RBPs. Jack Donald Keene was born in Jacksonville, Florida on June 22, 1947. His father worked for the RAND Corporation. Keene attended Redlands High School in Redlands, California, graduating in 1965. Initially a student at University of California, Los Angeles (UCLA), he transferred to the University of California, Riverside, where he majored in biology, working with Carlton Bovell. He received his A.B. degree in 1969. Next, Keene studied with Helen Riaboff Whiteley at the University of Washington in Seattle, Washington, graduating in 1975 with a doctorate in microbiology and Immunology. He did postdoctoral work in molecular virology with Robert A | https://en.wikipedia.org/wiki?curid=62262255 |
Jack D. Keene Lazzarini in the Laboratory for Molecular Genetics at the National Institutes of Health in Bethesda, Maryland from 1974-1978. In 1979, Keene was recruited by Wolfgang Joklik to the Department of Microbiology and Immunology at Duke University Medical Center. At that time the department was ranked one of the top three in the United States by the National Research Council. Keene was the chairman of the Department of Microbiology from 1992-2002, and Director of Basic Sciences for the Duke Comprehensive Cancer Center from 1995-2003. As of 1997 he became the James B. Duke Professor of Molecular Genetics and Microbiology at Duke University. In 1999 Keene founded the Duke Center for RNA Biology. Keene studies the regulation of RNA and the mechanisms of RNA-protein interactions. In his work on molecular genetics, he and his coworkers have examined the role of DNA and RNA-binding proteins (RBPs) in the pathogenesis of autoimmunity. In the late 1970s and early 1980s he identified genomic sequences for vesicular stomatitis virus (VSV) and rabies virus (RABV), members of the Rhabdoviridae family of viruses, and for Ebola virus and Marburg virus from the broader group of negative-strand RNA viruses (NSRV). He identified the origins of defective interfering particles of negative-strand RNA viruses. Through combinatorial studies of viral and bacterial systems, he has identified targets for novel pharmacological studies. Later in the 1980s, Keene identified RNA recognition motif (RRM) proteins | https://en.wikipedia.org/wiki?curid=62262255 |
Jack D. Keene RRM proteins are the largest family of RNA-binding proteins and the seventh largest protein family of the human genome. RRM is a prevalent RNA-binding fold involving proteins implicated in RNA biogenesis, processing, transport, and degradation. In 1987, Query and Keene first identified a B-cell epitope within the U1-70K protein. Keene isolated the first human autoimmune antigen and elucidated its autoimmune epitopes, the parts of an antigen to which antibodies in the immune system can bind. He cloned rheumatological autoimmune protein genes. He developed a diagnostic test for systemic lupus erythematosus using recombinant antigens. Keene's lab has identified functions of the ELAV/Hu posttranscriptional regulators HuB, HuC and HuD and their roles and that of HuR in processes of growth, proliferation, differentiation, and immune response. The study of RNA-binding proteins such as HuR and the determination of the binding of specific sequences have informed Keene's later post-transcription theory and his coordination theory of RNA operons. RNA-binding proteins appear to be implicated in the functioning of many posttranscriptional processes. As of 1994, Keene suggested that RNA-binding proteins could be involved in the regulation of messenger RNA that encode cytokines. In 2000, he was able to apply this approach to demonstrate neuronal differentiation | https://en.wikipedia.org/wiki?curid=62262255 |
Jack D. Keene He also introduced the first use of the RIP (ribonucleoprotein immunoprecipitation) protocol, isolating specific mRNPs using immunoprecipitation, and identifying the mRNA component with microarray or deep sequencing. This method has become a tool for the mapping of mRNA targets of specific RBPs. In 2001-2002, Keene formalized the posttranscriptional operon and regulon (PTRO) model for global gene regulation. By 2007, Keene proposed the RNA regulon hypothesis, "that mRNAs encoded by functionally related genes may be coordinately regulated as posttranscriptional RNA regulons by specific mRNP processing machineries". The purpose of the RNA regulon model was to better understand post-transcriptional regulation, to answer the question "How does the cell coordinate metabolism and regulation of mRNAs encoding proteins in the same biological process so that the proteins can be coordinately produced?" | https://en.wikipedia.org/wiki?curid=62262255 |
Pierre Sinaÿ Pierre Sinaÿ, born on April 11, 1938 in Aulnay-sous-Bois (Seine-et-Oise), is a French organic chemist. After studying at the École nationale supérieure des industries chimiques de Nancy from 1958 to 1961, he obtained a doctorate under the supervision of Professor Serge David in 1966 and continued for two years at Harvard University in Massachusetts (United States) as a post-doctoral researcher with Professor Roger W. Jeanloz. He then entered the University of Orléans in 1969 as a professor, where he was Director of the Institute of Organic and Analytical Chemistry from 1978 to 1987. He then became Professor of Chemistry in 1986 at the Université Pierre-et-Marie-Curie, where he then headed the Laboratory of Selective Processes in Organic and Bioorganic Chemistry in the Department of Chemistry at the École normale supérieure. He then became Professor Emeritus at Sorbonne University in 2006 and joined the Paris Institute of Molecular Chemistry. Pierre Sinaÿ's scientific work focuses on the chemistry of carbohydrates and the understanding of the role of oligosaccharides in the living world. In the mid-1970s, discovered and developed an effective method for oligosaccharide synthesis known as imidate glycosylation. This, by now allowing access to increasingly complex carbohydrate structures, is not unrelated to the development of glycobiology, the aim of which is to decode the meaning of this third alphabet of saccharides, which is in addition to that of proteins and nucleic acids | https://en.wikipedia.org/wiki?curid=62285853 |
Pierre Sinaÿ He synthesized the antigenic determinants of substances in human blood groups and then synthesized a complexly structured pentasaccharide representing the active site of heparin responsible for its antithrombotic effect. This last achievement demonstrates for the first time, without any ambiguity, the molecular basis of such an activity, commonly used in hospital medicine. This breakthrough in glyco-chemistry has led to the concept of conformational flexibility, which is crucial in heparinology. First materialized by the use of nuclear magnetic resonance, this concept was studied in detail using the chemical synthesis of constrained sugars adopting unconventional conformations. has also discovered and developed a whole series of conceptually new reactions. Selective examples include the synthesis of spiroorthoesters by using selenium chemistry, the development of organometallic chemistry of anomeric carbon, the pioneering synthesis of C-disaccharides, electrochemical glycosylation and, more recently, a novel functionalization of cyclodextrins through a kind of molecular microsurgery in which aluminium derivatives are said to be the scalpel. For the first time, the existence of the glycosyl cation, an intermediate conventionally postulated during glycosylation reactions, could be formally demonstrated through chemistry in a superacid environment. A 4-volume book covers many aspects of carbohydrate chemistry and biology. | https://en.wikipedia.org/wiki?curid=62285853 |
Nano-interfaces in bone bones are the skeleton of our bodies. They allow us the ability to move and lift our body up against gravity. bones are attachment points for muscles that help us to do many activities such as walking, jumping, kneeling, grasping, etc. Bones also protect organs from injury. Moreover, bone is responsible for blood cell production in a humans body. The mechanical properties of bone greatly influence the functionality of bone. For instance, deterioration in bone ductility due to diseases such as osteoporosis can adversely affect individuals’ life. Bone ductility can show how much energy bone absorbs before fracture. In bone, the origin ductility is at the nanoscale. The nano interfaces in Bone are the interface between individual collagen fibrils. The interface is filled with non-collagenous proteins, mainly osteopontin (OPN) and osteocalcin (OC). The osteopontin and osteocalcin form a sandwich structure with HAP minerals at nano-scale. The nano Interfaces are less than 2 – 3 % of bone content by weight, while they add more than 30% of the fracture toughness . The current knowledge of the structure and deformation mechanisms in nano-interfaces is limited. For the first time, a study unravel the complex synergic deformation mechanism in the nano-interfaces in bone. A synergistic deformation mechanism of the proteins through strong anchoring and formation of dynamic binding sites on mineral nano-platelets were seen | https://en.wikipedia.org/wiki?curid=62307595 |
Nano-interfaces in bone The nano-interface can sustain a ductility approaching 5000% and outstanding specific energy to failure that is several times larger than the most known tough natural materials such as spider silk. | https://en.wikipedia.org/wiki?curid=62307595 |
S-Methylcysteine "S"-Methylcysteine is the amino acid with the nominal formula CHSCHCH(NH)COH. It is the S-methylated derivative of cysteine. This amino acid occurs widely in plants, including many edible vegetables. The amino acid is not genetically coded, but it arises by post-translational methylation of cysteine. One pathway involves methyl transfer from alkylated DNA by zinc-cysteinate-containing repair enzymes. Beyond its biological context, it has been examined as a chelating agent. | https://en.wikipedia.org/wiki?curid=62309271 |
James L. Skinner (born August 17, 1953) is an American theoretical chemist. He is the Joseph O. and Elizabeth S. Hirschfelder Professor Emeritus at the University Wisconsin-Madison. He is also a member of the Scientific Advisory Board of the Welch Foundation. Most recently, Skinner was the Crown Family Professor of Molecular Engineering, Professor of Chemistry, Director of the Water Research Initiative and Deputy Dean for Faculty Affairs of the Pritzker School of Molecular Engineering at the University of Chicago. Skinner is recognized for his contributions to the fields of theoretical chemistry, nonequilibrium statistical mechanics, linear and nonlinear spectroscopy of liquids, amorphous and crystalline solids, surfaces, proteins, and supercritical fluids. Skinner is the co-author of over 230 peer-reviewed research articles. Skinner received his A. B. in Chemistry and Physics, both with highest honors, from the University of California, Santa Cruz in 1975. He received a Ph.D. in Chemical Physics from Harvard University in 1979 where he was a recipient of an NSF Graduate Fellowship and studied under the guidance of Peter G. Wolynes. The following year Skinner spent as an NSF Postdoctoral Fellow at Stanford University where he worked with Hans Andersen and Michael Fayer. Skinner joined the Department of Chemistry at Columbia University as an Assistant Professor of Chemistry in 1981. He was promoted to Associate Professor in 1985 and became a Professor of Chemistry in 1986 | https://en.wikipedia.org/wiki?curid=62324970 |
James L. Skinner In 1990 Skinner was appointed as the Director of the Theoretical Chemistry Institute and became the Joseph O. and Elizabeth S. Hirschfelder Professor of Chemistry at the University of Wisconsin-Madison. From 2004 to 2007 Skinner served as the chair of the Department of Chemistry at the University of Wisconsin-Madison. In 2015-2016 he served on the University of Wisconsin Campus Planning Committee and the Academic Planning Council. Skinner resigned his position as the Director of the Theoretical Chemistry Institute and retired from the University of Wisconsin-Madison in December 2016, where he currently holds the title of Joseph O. and Elizabeth S. Hirschfelder Professor Emeritus. In January 2017 Skinner joined the Institute for Molecular Engineering (now Pritzker School of Molecular Engineering) at the University of Chicago as the Crown Family Professor of Molecular Engineering. He also served as the Director of the Water Research Initiative and Deputy Dean for Faculty Affairs at the Pritzker School of Molecular Engineering. In 2020 he moved back to his position at the University of Wisconsin. During his career Professor Skinner has held multiple professional appointments. From 1993 to 1996 he was, consequently, the Vice-Chair, Chair-Elect, and Chair of the Theoretical subdivision of the Physical Division of the American Chemical Society and from 2000 to 2004 he was the Vice-Chair-Elect, Vice-Chair, Chair-Elect, and the Chair of the Physical Division of the American Chemical Society | https://en.wikipedia.org/wiki?curid=62324970 |
James L. Skinner From 2000 to 2003 Skinner was a Vice-Chair and then Chair of the Gordon Conference on Molecular Electronic Spectroscopy. In 2007 he was a member of the Committee of Visitors of the NSF Chemistry Division. From 2007 to 2010 Skinner was a member-at-large of the Chemical Physics Division of the American Physical Society. From 2011 to 2014 he was the Vice-Chair, Chair-Elect, and the Chair of Chemical Physics Division of the American Physical Society. Since 2008 Skinner was a vice-chair and in 2014 he was the chair of American Conference on Theoretical Chemistry. While at the University of Chicago, Skinner actively participated in the University of Chicago-Argonne National Laboratory partnership by serving on the advisory board of the Midwest Integrated Center for Computational Materials in 2016. Since 2015 he is an active member of the Scientific Advisory Board of the Welch Foundation. Since 2017 Skinner has been actively involved in the governance of the Telluride Science and Research Center (TSRC). From 2017 to 2019 he was a member of the Board of Directors of TSRC, becoming President of TSRC in 2018. Skinner has served on editorial boards of several scientific journals including Single Molecules (2000-2003), Journal of Physical Chemistry (2004-2006), Chemical Physics (2005-2009), and Molecular Physics (2008-2014). Skinner had a long-standing relationship with the Journal of Chemical Physics. In 1999 he joined the editorial board, and became an Associate Editor in 2009 | https://en.wikipedia.org/wiki?curid=62324970 |
James L. Skinner Since 2015 Skinner served as a Deputy Editor of the Journal of Chemical Physics, retiring from his editorial service in 2019. Throughout his career Skinner has received numerous awards including the ACS Irving Langmuir Award in Chemical Physics (2012), ACS Division of Physical Chemistry Award in Theoretical Chemistry (2011), Hilldale Award in the Physical Sciences, University of Wisconsin-Madison (2015), Wisconsin Alumni Research Foundation (WARF) named professorship, University of Wisconsin Chancellor’s Distinguished Teaching Award (2003), Pharmacia Teaching Award, Department of Chemistry, University of Wisconsin-Madison (2000), Phi Lambda Upsilon Fresenius Award (1989), Camille and Henry Dreyfus Teacher-Scholar Award (1984–89), National Science Foundation Presidential Young Investigator (1984-1989), National Science Foundation Postdoctoral Fellowship (1980-1981), and National Science Foundation Graduate Fellowship (1975-1978). Skinner is a member of the National Academy of Sciences (2012), American Academy of Arts and Sciences (2006), American Association for the Advancement of Science (2003). He is an Alfred P. Sloan Fellow (1984–88), Guggenheim Fellow (1993-94), Humboldt Foundation Senior Scientist (1993–97), Fellow of the American Chemical Society (2012) and American Physical Society (1997). James Skinner has been married to Wendy Skinner since 1986. They have two sons, Colin and Duncan. | https://en.wikipedia.org/wiki?curid=62324970 |
Nikolai Ivanovich Ivanov (entrepreneur) Nikolai Ivanovich Ivanov (; April 8, 1836 – February 13, 1906) was a Russian businessman operating out of Tashkent, Russian Turkestan. He was known as the largest and most successful entrepreneur and commerce advisor in Tashkent, owning multiple distilleries and breweries in Tashkent and other Central Asian cities. Born the son of a small merchant from Orenburg, Ivanov began his career in business at the age of fifteen as an errand boy. Thanks to his abilities, Ivanov rose up the ranks without graduating from school. He worked at the Yenisei gold mines, and was working independently by 1865, performing government contracts in Turkestan. Ivanov was interested in chemical enterprises. He owned plants in Tashkent that produced artificial ice and mineral water, as well as distilleries of vodka. In 1874, Ivanov was the first person in Tashkent to set up production of beer. The reputation of his "sixth brewery" was high until the end of the 20th century owing to the high quality of his products. Having bought the Degress estate near Tashkent, Ivanov organized winemaking events there and began to produce vintage wines. Pre-Russian Revolution wine tasters enjoyed Ivanov's wines, particularly the brand of Semilion, Sultani, Muscat and Siabchashma. Ivanov's various factories operated out of many cities in Turkestan. Ivanov owned a company that mined "Dragomirovsky Coal", and between the years of 1882 and 1895, before the construction of the Tashkent Railway, he controlled the Tashkent postal station, Terekli Station (1 | https://en.wikipedia.org/wiki?curid=62331996 |
Nikolai Ivanovich Ivanov (entrepreneur) 4 thousand kilometers long), the only transport station connecting Turkestan with the Russian heartland. Ivanov was known as the largest producer of high-quality vodka in Turkestan. His factories carried out full production cycles. In 1882, Ivanov was approached by German chemist Wilhelm Pfaff with a proposal to organize santonin production in Shymkent, as the city was near the Arys river valley, where santonin could be extracted naturally from plants. Ivanov built the Savinkov-Ivanov Chemical-Pharmaceutical Plant, and heavy equipment was carried from Altona, Hamburg to Shymkent through Orenburg on camel-drawn wagons with specially designed wheels and axels. The plant started production in 1882. It is now known as Chimfarm JSC, a prominent pharmaceutical company in Kazakhstan. As the santonin was shipped to Japan, India, Germany and England, the plant became known around the world. In Ivanov's Turkestan enterprises, owned by his firm, 2700 workers were employed. In 1881, Ivanov established the Central Asian Commercial Bank. For many decades, Ivanov was looked up to as an elder by businesspeople in Tashkent, receiving the honorary title of "Commerce Advisor". He was given several awards for his success. Ivanov was also known for the fact that he donated much money to the Russian Orthodox Church for the construction and arrangement of churches, charity houses, shelters and other structures. Ivanov was married to Alexandra Petrovna Ivanova (December 14th, 1845 - August 13th, 1913, Tashkent) | https://en.wikipedia.org/wiki?curid=62331996 |
Nikolai Ivanovich Ivanov (entrepreneur) He had 3 sons - Ivan, Vasily, and Alexander, as well as a daughter, Olga Nikolaevna Ivanova. These children were the owners of the firm "Heirs of Commerce Advisor N. I. Ivanov", having inherited their father's enterprises. Olga (later married to Orenburg merchant Nikifor Prokofievich Savinkov) (died October 27, 1915) was the co-owner of the santonin factory in Shymkent and the first female chemical engineer and pharmacist in Russian Turkestan. Ivanov's summer residence near Tashkent was transformed into a Russian Orthodox cemetery after his death. The cemetery is now known as the Botkin Cemetery for the street it is located on. It is the largest memorial, cultural and historical complex in Tashkent. Near the Temple to Alexander Nevsky on the territory of the Botkin Cemetery is Ivanov's grave. | https://en.wikipedia.org/wiki?curid=62331996 |
Paul Dauenhauer (born 1980), a chemical engineer, is the Lanny Schmidt Honorary Professor at the University of Minnesota (UMN). He is recognized for his research in catalysis science and engineering, especiall, his contributions to the understanding of the catalytic breakdown of cellulose to renewable chemicals, the invention of oleo-furan surfactants, and the development of catalytic resonance theory. was born in 1980 in Texas, USA, and was raised in Wisconsin Rapids, WI, attending Lincoln High School. He received his bachelor's degree in chemical engineering and chemistry at the University of Wisconsin, Madison in 2004. Working under the supervision of Lanny Schmidt at the University of Minnesota, Dauenhauer received his Ph.D. in chemical engineering in 2008 from the Department of Chemical Engineering & Materials Science. His dissertation described the development of reactive flash volatilization and was titled "Millisecond autothermal catalytic reforming of carbohydrates for synthetic fuels by reactive flash volatilization". Following graduation from Minnesota, Dauenhauer served as a Senior Research Engineer at the Dow Chemical Company in Midland, MI, and Freeport, TX. He started as an Assistant Professor at the University of Massachusetts, Amherst in 2009 before promotion to Associate Professor in 2014. In 2014, he moved to the Department of Chemical Engineering & Materials Science (CEMS) at the University of Minnesota, where he was promoted to Professor, and then and Lanny Schmidt Honorary Professor in 2019 | https://en.wikipedia.org/wiki?curid=62335808 |
Paul Dauenhauer During this time, he co-founded or contributed to the founding of startup companies Activated Research Company, Sironix Renewables, and enVerde, LLC. Dauenhauer's focus on renewable chemicals produced from glucose has targeted both drop-in replacement chemicals and new chemicals with novel characteristics. In 2012, he discovered a high yield pathway to synthesize p-xylene from glucose; this molecule is the key ingredient in polyethylene terephthalate plastic. This process technology utilized a new class of weak acid zeolites that permits the manufacture of biorenewable polyester. In 2015, Dauenhauer and his team developed a new class of surfactants, detergents, and soaps that are derived from biomass (furans from sugars and fatty acids from triglycerides, oleo-furan sulfonates (OFS). These molecules were shown to have high hard water stability (>1000 ppm Ca++) and are being commercialized by Sironix Renewables, Inc. In 2016, Dauenhauer and Abdelrahman developed the acid-catalyzed dehydra-decyclization mechanism that simultaneously opens cyclic ether rings and dehydrates to synthesize diene products. This technology was subsequently used to optimize the catalytic production of isoprene, the key chemical in the production of car tires. Subsequent research identified pathways to similarly convert biomass-derived tetrahydrofuran to butadiene and 2-methyl-tetrahydrofuran to piperylene | https://en.wikipedia.org/wiki?curid=62335808 |
Paul Dauenhauer Key publications include: Dauenhauer's study of cellulose in 2008 led to the discovery of an intermediate liquid state of short-chain cellulose oligomers of sub-second duration at temperatures around 500 deg C. He further outlined the challenges in understanding high temperature cellulose chemistry by publishing his "Top Ten Challenges" of biomass pyrolysis in 2012, one of which was based on his discovery of the mechanism of aerosol formation through liquid intermediate cellulose. Dauenhauer further developed a new reactor technique called 'PHASR' (Pulse-Heated Analysis of Solid Reactions) which led to the first isothermal kinetics of cellulose conversion and product formation. This technique permitted a molecular analysis of cellulose activation and the discovery that cellulose has a unique reaction transition at 467 deg C. The high temperature kinetic transition was attributed to the catalytic role of chain-to-chain cellulose hydroxyl groups in stabilizing the chain fragmentation of inter-monomer bonds. Key publications include: Catalytic resonance theory was proposed by Dauenhauer based on the Sabatier principle of catalysis developed by French chemist Paul Sabatier. Optimal catalyst performance is depicted as a 'volcano' peak using a descriptor of the chemical reaction defining different catalytic materials. Experimental evidence of the Sabatier principle was first demonstrated by Balandin in 1960 | https://en.wikipedia.org/wiki?curid=62335808 |
Paul Dauenhauer In his initial discovery of the behavior of oscillating chemical reactions on metal surfaces, Dauenhauer showed that steady state reaction rates could achieve chemical reaction speeds as much as 1000 times greater than previously achievable rates, even with optimized catalytic systems. This work broke down surface chemical reactions into its component parts and associated natural frequencies, which could be matched to resonate with the catalytic surface frequencies. Follow-up work on "catalytic resonance theory" by Dauenhauer and his team broadened to understand the relationship between surface chemistry with its linear scaling relationships and the surface binding energy oscillation waveform. He introduced the concept of "superVolcanoes" as a superposition of all possible Sabatier volcanoes for varying linear scaling parameters, before further connecting the behavior of oscillating catalytic surfaces to molecular machines and pumps. Key publications include: Professor Dauenhauer has supervised 12 Ph.D. students and advised six post-doctoral scholars. He has published over 90 peer-reviewed papers and 10 patents. He has given over 50 invited seminars and lectures including the Notre Dame Thiele lecture in 2017 and the Purdue Mellichamp lecture in 2016. He has received numerous awards for his work including: | https://en.wikipedia.org/wiki?curid=62335808 |
Ove Christiansen (born November 13, 1969 in Holstebro, Denmark) is professor of chemistry at the Department of Chemistry, Aarhus University (AU), Denmark. He is contributor to the DALTON program package and initiated the MidasCpp (Molecular Interactions Dynamics and Simulations in C++) program for the accurate description of nuclear dynamics with means of Coupled Cluster Theory. made important contributions to electronic structure theory by introducing the CC2 and CC3 method and by establishing a hierarchy of Coupled cluster electronic structure models: CCS, CC2, CCSD, CC3, etc.. He introduced contributions to response theory for the purpose of describing electronic excited states . Later he changed the emphasis of his main research interest towards vibrational structure theory and defined a variant of vibrational Coupled cluster (VCC) and developed the theoretical machinery for automatic derivation and implementation of VCC. Moreover, he defined vibrational response theory for various wave function types. All these progress is assembled in the publicly available MidasCpp program suite . received his PhD in Theoretical Chemistry under the supervision of Prof. Poul Jørgensen at Aarhus University Denmark in 1997. Afterwards he joined from 1997 to 1999 as Alexander von Humboldt fellow the group of Prof. Jürgen Gauß in Mainz Germany and later went to the University of Lund in Sweden, where he became a Docent in 2000 | https://en.wikipedia.org/wiki?curid=62343336 |
Ove Christiansen In 2002 he returned to Aarhus University as Associate Professor, became Professor MSO (Professor with special obligations) in 2013 and was promoted to a full Professor in 2018. | https://en.wikipedia.org/wiki?curid=62343336 |
Uri Banin (Hebrew: אורי בנין) is an Israeli chemist and a professor at the Hebrew University of Jerusalem, currently holding the Alfred & Erica Larisch Memorial Chair at the Institute of Chemistry. He is recognized as one of the pioneers of nanoscience in Israel. Banin is an associate editor of Nano Letters. Banin served in the Israeli Defense Forces as a captain of a Dabur-class boat. Following his military service, in 1986 Banin proceeded on to his academic career, receiving his Bachelor of Science degree in chemistry and physics from the Hebrew University of Jerusalem in 1989. He later received PhD from the Hebrew University, under the supervision of Sanford Ruhman in the field of femtosecond spectroscopy, studying the ultrafast dynamics of triiodide in solution. In 1994 Banin joined the group of Paul Alivisatos in UC Berkeley as a postdoctoral researcher, studying the physical chemistry of semiconductor nanocrystals. In 1997 he joined the Institute of Chemistry at the Hebrew University of Jerusalem as a senior lecturer, becoming a full professor in 2004. In the early days of his independent career at the Hebrew University, Banin used tunneling spectroscopy techniques in order to study the electronic properties of semiconductor nanocrystals, ultimately reporting the identification of atomic-like electronic states in 1999 in Nature | https://en.wikipedia.org/wiki?curid=62357093 |
Uri Banin His later work has diverged in the directions of both synthesis of novel semiconductor-based nanomaterials, the physical characterization of such nanostructures, as well as various applications. In 2003 his group has reported the first successful growth of colloidal zinc-blende lattice III-V semiconductor nanorods. Continuing the work on III-V semiconductor nanocrystals, the group has published the synthesis of bright near-infrared-emitting core/shell nanocrystals, later employing them in a novel nanocrystal-polymer near-infrared light-emitting diode. In 2011 the group reported a simple procedure for the doping on nanocrystals, allowing the synthesis of heavily-doped p-type and n-type semiconductor nanocrystals. Some of his earlier works include the study of cadmium chalcogenide molecular clusters as a step between complexes and nanocrystals with semiconducting properties. Setting this work aside since 2002, his next paper on the subject was only in 2017 reporting magic sized InP and InAs clusters. Subsequent work on related clusters with the groups of Richard D. Robinson and Tobias Hanrath has finally lead to the discovery of the reversible isomerization of inorganic clusters – a discovery made by chance during the shipping of the samples. This work was called "the final bridge" between molecules and nanocrystals | https://en.wikipedia.org/wiki?curid=62357093 |
Uri Banin One of the most recognized contribution of Banin to the field of colloidal nanostrucutres is the first demonstration of selective metal growth on semiconductor nanocrystals, resembling well-known bulk systems such as the Schottky diode, and the subsequent refinement of related synthesis procedures and the discovery of similar structures, as well as the physical characterization of such systems. To this day, hybrid metal-semiconductor nanostructures are state-of-the-art systems in the field of photocatalysis. One of the breakthroughs made by Banin's lab, employing hybrid metal-semiconductor nanocrystals in water-based 3D printing and photopolymerization of common acrylates. It was also later shown that such approach can also be used for solvent-free photopolymerization and microprinting. Banin is widely recognized as a pioneer of nanoscience in Israel, founding the Harvey M. Kreuger Family Center for Nanoscience and Nanotechnology in 2001 and serving as its first director for nearly a decade until 2010. He was the chairman of the scientific committee and a co-chairperson of the first international nanoscience conference in Israel in 2009, now an internationally-recognized biennial conference. In 2009, Banin became the scientific founder of Qlight Nanotech, which was later fully acquired by Merck KGaA for an undisclosed price and is currently located in the campus of the Hebrew University in Givat Ram | https://en.wikipedia.org/wiki?curid=62357093 |
Uri Banin In 2019 Nanosys signed an exclusive agreement on quantum dot patents developed in Banin's lab and held by Yissum. Banin has been an associate editor of the American Chemical Society journal Nano Letters since 2013. As of 2019, Banin has authored more than 350 papers that have been cited more that 23,500 times, granting him an h-index of 78. In addition, he has invented more than 35 different patents. Numerous former students and postdoctoral researchers of Banin are faculty members of Israeli and other universities. | https://en.wikipedia.org/wiki?curid=62357093 |
Solvent vapour annealing (SVA) is a widely used technique for controlling the morphology and ordering of block copolymer (BCP) films. By controlling the block ratio ("f" = "N"/"N"), spheres, cylinders, gyroids and lamellae structures can be readily generated by swelling of the BCP thin film using solvent vapor to facilitate the self-assembly of the polymer blocks. It is a more mild alternative to thermal annealing. | https://en.wikipedia.org/wiki?curid=62377568 |
Induced cell cycle arrest is the use of a chemicals or genetic manipulation to artificially halt progression through the cell cycle. Cellular processes like genome duplication and cell division stop. It can be temporary or permanent. It is an artificial activation of naturally occurring cell cycle checkpoints, induced by exogenous stimuli controlled by an experimenter. In an academic research context, cell cycle arrest is typically performed in model organisms and cell extracts, such as "Saccharomyces cervisiae" (yeast) or "Xenopus" oocytes (frog eggs). Frog egg cell extracts have been used extensively in cell cycle research because they are relatively large, reaching a diameter of 1mm, and so contain large amounts of protein, making protein levels more easily measurable. There are a variety of reasons a researcher may want to temporarily or permanently prevent progress through the cell cycle. In some experiments, a researcher may want to control and synchronize the time when a group of cells progress to the next phase of the cell cycle. The cells can be induced to arrest as they arrive (at different time points) at a certain phase, so that when the arrest is lifted (for instance, rescuing cell cycle progression by introducing another chemical) all the cells resume cell cycle progression at the same time. In addition to this method acting as a scientific control for when the cells resume the cell cycle, this can be used to investigate necessity and sufficiency | https://en.wikipedia.org/wiki?curid=62380746 |
Induced cell cycle arrest Another reason synchrony is important is the control for amount of DNA content, which varies at different parts of the cell cycle based on whether DNA replication has occurred since the last round of completed mitosis and cytokinesis. Furthermore, synchronization of large numbers of cells into the same phase allows for the collection of large enough groups of cells in the same cycle for the use in other assays, such as western blot and RNA sequencing. Researchers may be investigating mechanisms of DNA damage repair. Given that some of the mechanisms below of inducing cell cycle arrest involve damaging the DNA, this allows investigation into how the cell responds to damage of its genetic material. Genetic engineering of cells with specific gene knockouts can also result in cells that arrest at different phases of the cell cycle. Examples include: G phase is the first of the four phases of the cell cycle, and is part of interphase. While in G the cell synthesizes messenger RNA (mRNA) and proteins in preparation for subsequent steps of interphase leading to mitosis. In human somatic cells, the cell cycle lasts about 18 hours, and the G phase makes up about / of that time. On the other hand, in frog, sea urchin, and fruit fly embryos, the G phase is extremely brief and instead is a slight gap between cytokinesis and S phase. α-factor is a pheromone secreted by "Saccharomyces cervisiae" that arrests the yeast cells in G phase. It does so by inhibiting the enzyme adenylate cyclase | https://en.wikipedia.org/wiki?curid=62380746 |
Induced cell cycle arrest The enzyme catalyzes the conversion of adenosine triphosphate (ATP) to 3',5'-cyclic AMP (cAMP) and pyrophosphate. Contact inhibition is a method of arresting cells when neighboring cells come into contact with each other. It results in a single layer of arrested cells of arrested cells, and is a process that is notably missing in cancer cells. The suspected mechanism is dependent on p27, a cyclin-dependent kinase inhibitor. p27 protein levels are elevated in arresting cells. This natural process can be mimicked in a lab through the overexpression of p27, which results in induced cell cycle arrest in G phase. Mimosine is a plant amino acid that has been shown to reversibly inhibit progression beyond G phase in some human cells, including lymphoblastoid cells. Its proposed mechanism of action is an iron/zinc chelator that depletes iron within the cell. This induces double-strand breaks in the DNA, inhibiting DNA replication. This may involve blocking the action of an iron-dependent ribonucleotide reductase. It may also inhibit transcription of serine hydroxymethyltransferase, which has zinc dependence. In cell culture, serum is the growth medium in which the cells are grown and contains viral nutrients. The use of serum deprivation - partially or completely removing the serum and its nutrients - has been shown to arrest and synchronize cell cycle progression in G phase, for example in neonatal mammalian astrocytes and human foreskin fibroblasts. Amino acid starvation is a similar approach | https://en.wikipedia.org/wiki?curid=62380746 |
Induced cell cycle arrest When grown in a media without some essential amino acids, such as methionine, some cells arrest in early G phase. S phase follows G phase via the G/S transition and precedes G phase in interphase and is the part of the cell cycle in which DNA is replicated. Since accurate duplication of the genome is critical to successful cell division, the processes that occur during S-phase are tightly regulated and widely conserved. Pre-replication complexes assembled before S phase are converted into active replication forks. Driving this conversion is Cdc7 and S-phase cyclin-dependent kinases, which are both upregulated after the G/S transition. Aphidicolin is an antibiotic isolated from the fungus "Cephalosporum aphidicola". It is a reversible inhibitor of eukaryotic nuclear DNA replication that blocks progression past the S phase. Its mechanism is the inhibition of DNA polymerase A and D. A structural study found that this is thought to occur through binding the alpha active site of the polymerase and "rotating the template guanine," which prevents deoxycytidine triphosphate (dCTP) from binding. This S phase block induces apoptosis in HeLa cells. 2[[3-(2,3-dichlorophenoxy)propyl] amino]ethanol (2,3-DCPE) is a [[Small molecule|small-molecule]] that induces S phase arrest. This was demonstrated in cancer cell lines and downregulates expression of B-cell lymphoma-extra large ([[Bcl-xL|Bcl-XL]]), an anti-apoptotic protein that prevents the release of mitochondrial contents like [[cytochrome c]] | https://en.wikipedia.org/wiki?curid=62380746 |
Induced cell cycle arrest [[G2 phase|G phase]] is the final part of interphase and directly precedes mitosis. It will only be entered in regular cells if the DNA replication in S phase is completed successfully. It is a period of rapid cell growth and protein synthesis during which the cell prepares itself for mitosis. [[Cyclin|Cyclins]] are proteins that control progression through the cell cycle by activating cyclin-dependent kinases. Destruction of a cell's [[endogenous]] cyclin messenger RNA can arrest frog egg extracts in [[interphase]] and prevent them from entering mitosis. Introduction of exogenous cyclin mRNA is also sufficient to rescue cell cycle progression. One method of this destruction is through the use of [[Antisense oligonucleotide|antisense oligonucleotides]], pieces of RNA that bind to the cyclin mRNA and prevent the mRNA from being translated into cyclin protein. This can actually be used to destroy phase-specific cyclins beyond just G - for instance, destruction of [[cyclin D1]] mRNA by antisense oligonucleotides prevents progression from G phase to S phase. [[File:Mitosis Stages.svg|thumb|Mitosis is the non-interphase part of the [[cell cycle]] and generates two daughter cells|alt=]] [[Mitosis]] is the final part of the cell cycle and follows interphase | https://en.wikipedia.org/wiki?curid=62380746 |
Induced cell cycle arrest It is composed of four phases - [[prophase]], [[metaphase]], [[anaphase]], and [[telophase]] - and involves the condensation of the [[Chromosome|chromosomes]] in the [[Cell nucleus|nucleus]], the dissolution of the [[nuclear envelope]], and the separation of [[sister chromatids]] by [[spindle fibers]]. As mitosis concludes, the spindle fibers disappear and the nuclear membrane reforms around each of the two sets of chromosomes. After successful mitosis, the cell physically splits into two identical [[daughter cells]] in a process called [[cytokinesis]], and this concludes a full round of the cell cycle. Each of these new cells could then potentially re-enter G phase and begin the cell cycle again. [[Hydroxyurea]] (HU) is a [[Small-molecule drug|small molecule drug]] that inhibits the enzyme [[ribonucleotide reductase]] (RNR), preventing the catalysis of converting [[Deoxyribonucleotide|deoxyribonucleotides]] (DNTs) to [[Ribonucleotide|ribonucleotides]]. It is hypothesized that there is tyrosyl [[free radical]] within RNR that is disabled by HU. The free radicals are necessary for the reduction of the DNTs and are scavenged by HU instead. HU has been show to arrest cells in both S phase (healthy cells) and immediately before cytokinesis (mutant cells). [[Nocodazole]] is a chemical agent that interferes with the polymerization of microtubules. Cells treated with nocodazole arrest with a G or M phase DNA content, which can be verified with flow cytometry | https://en.wikipedia.org/wiki?curid=62380746 |
Induced cell cycle arrest From microscopy it has been determined they do enter mitosis but they cannot form the spindles necessary for metaphase because the microtubules cannot polymerize. Research into the mechanism has hinted at it potentially preventing tubulin from forming its alpha/beta heterodimer. [[Paclitaxel|Taxol]] works in the opposite way of nocodazole, instead stabilizing the microtubule polymer and preventing it from disassembly. It also causes M phase arrest, as the spindle that is supposed to pull apart sister chromatids is unable to disassemble. It acts through a specific binding site on the microtubule polymer, and as such does not require GTP or other cofactors to induce tubulin polymerization. Temperature has been shown to regulate HeLa cell cycle progression. Mitosis was found to be the most temperature-sensitive part of the cell cycle. Pre-cytokinesis mitotic arrest was visible through accumulation of cells in mitosis in below-normal temperatures between 24-31ºC (75.2-87.8ºF). There are several methods that can be used to verify that cells have been arrested in the proper phase. [[Flow cytometry]] is a technique of measuring physical and chemical characteristics of a population of cells using lasers and [[fluorophore]] dyes covalently linked to protein markers. The stronger the signal, the more of a particular protein is present | https://en.wikipedia.org/wiki?curid=62380746 |
Induced cell cycle arrest [[Staining]] with DNA dyes [[propidium iodide]] or [[4',6-diamidino-2-phenylindole|4',6'-diamidino-2-phenylindole]] (DAPI) allows delineation or sorting of cells between G S, or G/M phases. [[Immunoblotting]] is the detection of specific proteins in a tissue sample or extract. Primary antibodies recognize and bind the protein in question, and secondary antibodies are added that recognize the primary antibodies. The secondary antibody is then visualized through staining or [[immunofluorescence]], allowing indirect detection of the original target protein. Immunoblotting can be performed to detect the presence of [[Cyclin|cyclins]], proteins that regulate the cell cycle. Different classes of cyclins are up- and down-regulated at different parts of the cell cycle. Measurement of the cyclins from an extract of an arrested cell can determine what phase the cell is in. For example, a peak of [[cyclin E]] protein would indicate the [[G1/S transition|G/S transition]], a [[cyclin A]] peak would indicate late G phase, and a [[cyclin B]] peak would indicate mitosis. FUCCI is a system that takes advantage of cell cycle phase-specific expression of proteins and their [[Protein degradation|degradation]] by the [[Ubiquitin proteasome pathway|ubiquitin-proteasome pathway]]. Two [[fluorescent probes]] - [[Cdt1]] and [[Geminin]] conjugated to fluorescent proteins - allow for real-time visualization of the cell cycle phase a cell is in. [[Category:Cell cycle]] [[Category:Cell biology]] [[Category:Laboratory techniques]] | https://en.wikipedia.org/wiki?curid=62380746 |
Centre for Radiation, Chemical and Environmental Hazards The (CRCE) is a British government environmental research site, run by Public Health England (PHE) in Chilton, Oxfordshire that monitors levels of toxic chemicals and background radiation in the British environment; it is largely a continuation of the former National Radiological Protection Board (NRPB). The Radiation Protection Division of the Health Protection Agency was formed on 1 April 2005, due to the Health Protection Agency Act 2004, directly superseding the NRPB. This became the CRCE due to the Health and Social Care Act 2012, when Public Health England was formed. It is part of PHE's Radiation Protection Adviser Services. PHE was the UK's first Radiation Protection Adviser Body, under the Ionising Radiations Regulations (IRR) 17 (which came from the International Commission on Radiological Protection). It monitors background radiation in the UK. Workers exposed to radiation include workers in dental radiography and nuclear power stations; exposure to radiation for workers in the UK must be ALARP. It offers 3-day training courses around twice a month, at a national level, for workers exposed to radiation. It produces reports on environmental background radiation in England. It works with the ICRP, the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), and the International Atomic Energy Agency (IAEA). Inside the UK, it works with the Scottish Environment Protection Agency (SEPA) and the Environment Agency (EA). | https://en.wikipedia.org/wiki?curid=62383595 |
Marguerite S. Chang Marguerite Shue-wen Chang (張葉學文; June 21, 1923 – May 5, 2012) was a Chinese-born American research chemist and inventor, awarded the Federal Woman's Award in 1973 for her work in the United States Naval Ordnance Laboratory, based in Maryland. Marguerite Shue-wen Ye was born in Nanjing in 1923. She earned a bachelor's degree in chemistry at Wuhan University. She earned a master's degree and a Ph.D. in organic chemistry at Tulane University, where she was an associate member of the Sigma Xi honor society. Her dissertation advisor was Joseph H. Boyer. Chang moved to the United States in 1946. From 1959 she worked at the United States Naval Ordnance Laboratory in Maryland, developing propellants for missiles and rockets, working on safety procedures for the manufacture and use of propellants. She was named as an inventor on several patents, assigned to the United States government between 1976 and 1986, for processes, production methods and chemical compositions. Chang's scientific publications included "The Identification of CHNO, a Product from Acetophenone and Nitric Acid" ("Journal of the American Chemical Society" 1960, with Joseph H. Boyer), and "Bis(cyclopropanecarbonyl)furoxan" ("Journal of Organic Chemistry" 1968, with James U. Lowe Jr.). Chang is included in Conversations 760-009 and 871-009 of the White House Tapes, in the Oval Office for a photo sessions with President Richard Nixon and others in August 1972 and March 1973. She was one of the six women to receive the Federal Woman's Award in 1973 | https://en.wikipedia.org/wiki?curid=62388669 |
Marguerite S. Chang was married to George K. Chang. The couple moved to the United States together in 1946, and had two sons while Marguerite Chang was a graduate student at Tulane University. The Changs decided to stay in the United States after 1949. died in 2012, aged 88 years, in Palo Alto, California. | https://en.wikipedia.org/wiki?curid=62388669 |
Indentation size effect The indentation size effect (ISE) is the observation that hardness tends to increase as the indent size decreases at small scales. When an indent (any small mark, but usually made with a special tool) is created during material testing, the hardness of the material is not constant. At the small scale, materials will actually be harder than at the macro-scale. For the conventional indentation size effect, the smaller the indentation, the larger the difference in hardness. The effect has been seen through nanoindentation and microindentation measurements at varying depths. Dislocations increase material hardness by increasing flow stress through dislocation blocking mechanisms. Materials contain statistically stored dislocations (SSD) which are created by homogeneous strain and are dependent upon the material and processing conditions. Geometrically necessary dislocations (GND) on the other hand are formed, in addition to the dislocations statistically present, to maintain continuity within the material. These additional geometrically necessary dislocations (GND) further increase the flow stress in the material and therefore the measured hardness. Theory suggests that plastic flow is impacted by both strain and the size of the strain gradient experienced in the material. Smaller indents have higher strain gradients and therefore have a higher measured hardness in some materials | https://en.wikipedia.org/wiki?curid=62389592 |
Indentation size effect For practical purposes this effect means that hardness in the low micro and nano regimes cannot be directly compared if measured using different loads. However, the benefit of this effect is that it can be used to measure the effects of strain gradients on plasticity. Several new plasticity models have been developed using data from indentation size effect studies, which can be applied to high strain gradient situations such as thin films. | https://en.wikipedia.org/wiki?curid=62389592 |
Yangite (PbMnSiO•HO) is a chain-silicate mineral, first discovered within the Kombat mine in Namibia. The mineral is named after Hexiong Yang, a researcher within University of Arizona's Department of Geosciences. was approved as a valid mineral species by the International Mineralogical Association in 2012. was initially found within a specimen taken from the Kombat mine, located in the Otavi Valley, Namibia. The specimen was obtained from John Innes, a senior mineralogist of the Tsumeb Corporation. occurs in an ore defined as an epithermal association. This ore type forms with narrow veins composed of galena, rhodochrosite, helvite, and barite. is colorless, ranging to pale brown when exposed to transmitted light. The mineral has a vitreous luster and streaks white. maintains a Mohs hardness of five, and demonstrates perfect cleavage along {101}. There is no evidence of twinning or parting within the available specimens. is sectile, commonly found with bladed or platy habit. The mineral is biaxial, elongated up to 12 mm in length along the [010] axis. is insoluble in several fluids, including water, acetone, and hydrochloric acid. has a consistent chemical composition, determined using a CAMECA SX100 electron microprobe. Additionally, the presence of HO was confirmed using structural determination and Raman spectroscopic measurements. Elemental Weight Percent: was analyzed by both powder and single-crystal X-ray diffraction. Data was collected using the Bruker X8 APEX2 CCD diffractometer | https://en.wikipedia.org/wiki?curid=62394509 |
Yangite The diffraction data was influenced by severe peak overlap, leading to uncertainty in the resulting index. Powder Diffraction Data: The chain silicate structure is formed by double wollastonite chains. These tetrahedral formations run parallel with the [010] axis and connect with Mn-polyhedra and Pb-polyhedra at the corners. The chains are also defined by four-membered and six-membered alternating tetrahedral rings. has three Si tetrahedral sites, defined as Si1, Si2, and Si3. Respectively, the average bond lengths are 1.622 Å, 1.622 Å, and 1.624 Å. is composed of an octahedrally coordinated Mn cation. Within the crystal structure, Pb has a coordination number of five, bonded with O molecules. | https://en.wikipedia.org/wiki?curid=62394509 |
Cell cycle regulated Methyltransferase CcrM is an orphan DNA methyltransferase, that is involved in controlling gene expression in most Alphaproteobacteria. This enzyme modifies DNA by catalyzing the transference of a methyl group from the S-adenosyl-L methionine substrate to the N6 position of an adenine base in the sequence 5'-GANTC-3' with high specificity. In "Caulobacter crescentus" Ccrm is produced at the end of the replication cycle when Ccrm recognition sites are hemimethylated, rapidly methylating the DNA. CcrM is essential in other Alphaproteobacteria but is role is not yet determined. CcrM is a highly specific methyltransferase with a novel DNA recognition mechanism. Methylations are epigenetic modification that, in eukaryotes, regulates processes as cell differentiation, and embryogenesis, while in prokaryotes can have a role in self recognition, protecting the DNA from being cleaved by the restriction endonuclease system, or for gene regulation. The first function is controlled by the restriction methylation system while the second by Orphan MTases as Dam and CcrM. CcrM role have been characterized in the marine model organism "Caulobacter crescentus," which is suitable for the study of cell cycle and epigenetics as it asymmetrically divides generating different progeny, a stalked and a swarmer cell, with different phenotypes and gene regulation. The swarmer cell has a single flagellum and polar pili and is characterized by its mobility, while the stacked cell has a stalk and is fixed to the substrate | https://en.wikipedia.org/wiki?curid=62401003 |
Cell cycle regulated Methyltransferase The stacked cell enters immediately in S-phase, while the swarmer cell stays in G1-phase and will differentiate to a stacked cell before entering the S-phase again. The stacked cell in S phase will replicate its DNA in a semiconservative manner producing two hemimethylated DNA double strands that will be rapidly methylated by the Methyltransferase CcrM, which is only produced at the end of the S phase. The enzyme will methylate more than 4 thousand 5'-GANTC-3' sites in around 20 minutes, and then it will be degraded by the LON protease. This fast methylation plays an important role in the transcriptional control of several genes and controls the cell differentiation. CcrM expression is regulated by the CtrA master regulator, and in addition various 5'-GANTC-3' sites methylation sites regulate CcrM expression, which will only occur at the end of the S phase when this sites are hemimethylated. In this process CtrA regulates the expression of CcrM and more than 1000 genes in the pre-divisional state, and SciP prevents the activation of CcrM transcription in non replicative cells. Orphan MTases are common in bacteria and archea "." CcrM is found in almost every group of "Alphaproteobacteria", excepting in "Rickettsiales" and "Magnetococcales," and homologs can be found in"Epsilonproteobacteria" and "Gammaproteobacteria" " | https://en.wikipedia.org/wiki?curid=62401003 |
Cell cycle regulated Methyltransferase "Alphaproteobacteria are organisms with different life stages from free living to substrate associated, some of them are intracellular pathogens of plants, animal and even human, in those groups the CcrMs must have an important role in cell cycle progression. CcrM miss regulation have shown to produce severe miss control of cell cycle regulation and differentiation in various Alphaproteobacteria; "C. crescentus" , the plant symbiont "Sinorhizobium meliloti" and in the human pathogen "Brucella abortus". Also CcrM gene has proven to be essential for the viability of various Alphaproteobacteria. CcrM is a type II DNA Methyltransferase, that transfer a methyl group from the methyl donor SAM to the N6 of an adenine in a 5'-GANTC-3' recognition sites of hemimethylated DNA. Based on the order of the conserved motifs that form the SAM binding, the active site and the target recognition domain (TRD) in the sequence of CcrM it can be classified as a β-class adenine N6 Methyltransferase. CcrM homologs in Alphaproteobacteria have an 80 residues C terminal domain, with non well characterized function. CcrM is characterized by a high degree of sequence discrimination, showing a very high specificity for GANTC sites over AANTC sites , being able to recognize and methylate this sequence in both double and single strand DNA | https://en.wikipedia.org/wiki?curid=62401003 |
Cell cycle regulated Methyltransferase CcrM in complex with a dsDNA structure was resolved, showing that the enzyme presents a novel DNA interaction mechanism, opening a bubble in the DNA recognition site (The concerted mechanism of Methyltransferases relies in the flip of the target base), the enzyme interacts with DNA forming an homodimer with differential monomer interactions. CcrM is a highly efficient enzyme capable of methylating a high number of 5'-GANTC-3' sites in low time, however if the enzyme is processive (the enzyme binds to the DNA and methylate several methylation sites before dissociation) or distributive (the enzyme dissociates from DNA after each methylation) it is still in discussion. First reports indicated the second case, however more recent characterisation of CcrM indicate that it is a processive enzyme. | https://en.wikipedia.org/wiki?curid=62401003 |
Jena glass (German: "Jenaer Glas") is a shock- and heat-resistant glass used in scientific and technological applications, especially in chemistry. The glass was invented by Otto Schott in 1884 in Jena, Germany, where he had established Schott AG with Ernst Abbe and Carl Zeiss. is a borosilicate which, in early manufacture, contained added aluminum, magnesium, sodium, and zinc. It was a predecessor to other borosilicate glasses which came into wide use in the twentieth century, such as Pyrex. | https://en.wikipedia.org/wiki?curid=62408275 |
Trivalent group 14 radicals A trivalent group 14 radical (also known as a "trivalent tetrel radical") is a molecule that contains a group 14 element (E = C, Si, Ge, Sn, Pb) with three bonds and a free radical, having the general formula of RE•. Such compounds can be categorized into three different types, depending on the structure (or equivalently the orbital in which the unpaired electron resides) and the energetic barrier to inversion. A molecule that remains rigidly in a pyramidal structure has an electron in a sp orbital is denoted as "Type A". A structure that is pyramidal, but flexible, is denoted as "Type B". And a planar structure with an electron that typically would reside in a pure p orbital is denoted as "Type C". The structure of such molecules has been determined by probing the nature of the orbital that the unpaired electron resides in using spectroscopy, as well as directly with X-ray methods. Trivalent tetrel radicals tend to be synthesized from their tetravalent counterparts (i.e. REY where Y is a species that will dissociate). While the trivalent triphenylmethyl radical, which was the first organic radical described, has been known for over 100 years, characterization of transient, persistent, or stable radicals of heavier tetrel compounds have been only accessible in recent years (from the 1960s to the present). The most recent large advance has been the characterization of the first stable trivalent lead radical, as described in 2007 | https://en.wikipedia.org/wiki?curid=62409950 |
Trivalent group 14 radicals Such developments have only been made in recent years because these compounds tend to be highly reactive (with respect to reactions such as dimerization and radical chain reactions). There have been two main approaches for stabilization. Firstly "electronic stabilization", the tetrel is connected to an electron-rich atom such as oxygen, nitrogen, or fluorine. Secondly "steric stabilization", the tetrel is surrounded by bulky ligands (such as -Y(SiMe) (Y = N, CH), -Si(SiMe)Et (-Ebt), or -Si(SiMe) (-Hyp)). It has become convention to describe a radical that can persist long enough for spectroscopic or chemical analysis as "persistent" and a radical that can persist indefinitely as "stable". Trivalent tetrels can also synthesized in a cyclic structure (e.g. ArGe•). This class of molecules tends to be slightly more stable than the acyclic analogues as there is a stabilization through the delocalization of the unpaired electrons within the π-system. Trivalent radicals can be prepared from the tetrel hydride (for arbitrary radical species Z). They can also be formed by oxidation of the salt (typically with GeCl•dioxane in EtO). They can be formed via photolysis. Or they can be formed via thermal disproportionation (thermolysis) of the related dimeric species. These can also be formed via gamma-irradiation of an ER complex. As well as by a reduction pathway | https://en.wikipedia.org/wiki?curid=62409950 |
Trivalent group 14 radicals Information about the structure of these trivalent tetrels has been determined by mainly EPR spectroscopy and X-ray crystallography, however the geometry of transient small molecules has been determined via resonance-enhanced multiphoton ionization, transient UV absorption spectroscopy, and microwave spectroscopy by determining vibrational and rotational resonance frequencies. Electron paramagnetic resonance has been paramount for the study of trivalent tetrels as the hyperfine coupling to the tetrel reveals the orbital in which the unpaired electron resides, and the orbital composition directly correlates to the structure of the molecule. The isotropic component of the hyperfine coupling to the central tetrel scales proportionally with the spin density in the valence s orbital on that atom (see the Figure on the right). By comparing this isotropic hyperfine coupling constant to the theoretical hyperfine splitting of an electron in a pure valence s orbital, one can calculate the percent of the unpaired spin density in the valence s orbital. Similarly, the ratio of the anisotropic hyperfine coupling constant to the anisotropic hyperfine coupling of a single electron in a pure atomic p orbital reveals the percent of spin occupation in a valence p orbital. However, measurement of the anisotropic component of the hyperfine tensor are more difficult and not as frequent in literature. The percent of spin occupation in the valence s orbital can be used to directly probe the structure of these molecules | https://en.wikipedia.org/wiki?curid=62409950 |
Trivalent group 14 radicals If the spin occupation 100% in a p orbital, then the molecule will have a Type C planar structure. However, if there is 25% s orbital and 75% p orbital occupation, then the molecule will have a pyramidal Type A structure. Any intermediate value is possible and would correspond to a Type B structure. Values of greater than 25% s orbital contribution can also be found upon coordination of a tetrel to electronegative ligands (-OR, -F, -NR, -Cl). There is also a correlation between the g-shift (∆g = g - g) and the geometry for series of compounds with ligands of similar electronegativities. More electronegative ligands correspond to more tetrahedral geometries. Lower g values correlate more with pyramidal structures, while higher g values correlate with planar structures. It has also been demonstrated using tris(trialkylsilyl)silyl radicals that the more bulky the ligands are, the more a planar structure will be favored, and the lower the hyperfine coupling constant will be. It has been shown that there are two main factors that dictate whether a complex will be a Type A, B, or C structure. The lighter the tetrel, the more it will have a tendency to remain planar. This has been ascribed due to the pseudo Jahn–Teller effect, as the E-R anti-bonding orbitals (of RE•) can more significantly mix with the non-bonding SOMO (singly occupied molecular orbital) due to a more electropositive and diffuse central atom | https://en.wikipedia.org/wiki?curid=62409950 |
Trivalent group 14 radicals The barrier for inversion has been calculated at the NL-SCF/TZ2P level to be increasing for EH• C, Si, Ge, Sn at 0.0, 3.7, 3.8, 7.0 kcal/mol (the barrier for inversion of methyl radical is zero as it is most stable in a planar Type C structure). | https://en.wikipedia.org/wiki?curid=62409950 |
Herman T. Briscoe Herman Thompson Briscoe (November 6, 1893- October 8, 1960) was an American chemist and professor of chemistry. The Professorship in Chemistry at Indiana University was established in 1961, and the Quadrangle Dormitory was dedicated in 1966. was born on November 6, 1893, in Shoals, Indiana. Briscoe received his teaching certificate in 1912 from Indiana University in Bloomington, Indiana and began teaching at his home high school in Shoals for three academic years before becoming principal of Shoals high school and later superintendent of Shoals school district. He returned to Indiana University, earning his A.B. degree in chemistry with high distinction in 1917. Briscoe would then enlist in the U.S. army as a private in May of 1918, transferring to the Hercules Powder Company as a research chemist until his discharge in 1919. Between 1919 and 1922, Briscoe held successful teaching positions at Stark’s Military Academy, as an Austin Teaching Fellow at Harvard University, and at Colby College. Returning to Indiana University for a third time, received his A.M. and Ph.D. degrees in chemistry in 1924 under the guidance of Professor Frank C. Mathers. Married to Orah Elberta Briscoe in 1928, whose maiden name was Cole. Orah was born in 1907 in Liberty Center, IN. When they marries Herman was 14 years her senior. In 1929, their first child Catherine was born.They would have a total of 4 children. Orah was able to receive a BA in Latin in 1929 and a MA in English in 1934. After receiving his Ph.D | https://en.wikipedia.org/wiki?curid=62411787 |
Herman T. Briscoe , was appointed assistant professor of chemistry at Indiana University, working his way to professor of chemistry in 1928. Throughout his career, Briscoe authored or coauthored 23 publications on conductivity, physical properties, and the reactions of organic and inorganic molecules, supervised the graduate studies of 25 students, and published several general chemistry textbooks. In 1938, President of Indiana University Herman B. Wells appointed Briscoe as the secretary of the newly established self-survey committee, which sought the feedback of faculty and proposed administrative changes accordingly. In the same year, Briscoe was appointed Chairman of the Department of Chemistry of Indiana University following the recommendation of retiring Chairman Robert E. Lyons. Herman Briscoe would continue on to become Indiana University's first Dean of Faculties in 1939 and Vice President of Indiana University in 1940. Briscoe gave up his appointment as Chairman of the Department of Chemistry in order to focus on his administrative roles as Vice President and Dean of Faculties, in which he served until his retirement in 1959. | https://en.wikipedia.org/wiki?curid=62411787 |
Sven Gustaf Hedin (1859–1933) was a Swedish chemist and physiologist credited with the discovery of histidine. | https://en.wikipedia.org/wiki?curid=62419778 |
Perturbed angular correlation The perturbed γ-γ angular correlation, PAC for short or PAC-Spectroscopy, is a method of nuclear solid-state physics with which magnetic and electric fields in crystal structures can be measured. In doing so, electrical field gradients and the Larmor frequency in magnetic fields as well as dynamic effects are determined. With this very sensitive method, which requires only about 10-1000 billion atoms of a radioactive isotope per measurement, material properties in the local structure, phase transitions, magnetism and diffusion can be investigated. The PAC method is related to nuclear magnetic resonance and the Mössbauer effect, but shows no signal attenuation at very high temperatures. Today only the time-differential perturbed angular correlation (TDPAC) is used. PAC goes back to a theoretical work by Donald R. Hamilton from 1940. The first successful experiment was carried out by Brady and Deutsch in 1947. Essentially spin and parity of nuclear spins were investigated in these first PAC experiments. However, it was recognized early on that electric and magnetic fields interact with the nuclear moment, providing the basis for a new form of material investigation: nuclear solid-state spectroscopy. Step by step the theory was developed. After Abragam and Pound published their work on the theory of PAC in 1953 including extra nuclear fields, many studies with PAC were carried out afterwards | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation In the 1960s and 1970s, interest in PAC experiments sharply increased, focusing mainly on magnetic and electric fields in crystals into which the probe nuclei were introduced. In the mid-1960s, ion implantation was discovered, providing new opportunities for sample preparation. The rapid electronic development of the 1970s brought significant improvements in signal processing. From the 1980s to the present, PAC has emerged as an important method for the study and characterization of materials. B. for the study of semiconductor materials, intermetallic compounds, surfaces and interfaces. Lars Hemmingsen et al. Recently, PAC also applied in biological systems. While until about 2008 PAC instruments used conventional high-frequency electronics of the 1970s, in 2008 Christian Herden and Jens Röder et al. developed the first fully digitized PAC instrument that enables extensive data analysis and parallel use of multiple probes. Replicas and further developments followed. PAC uses radioactive probes, which have an intermediate state with decay times of 2 ns to approx. 10 μs, see example In in the picture on the right. After electron capture (EC), indium transmutates to cadmium. Immediately thereafter, the cadmium nucleus is predominantly in the excited 7/2+ nuclear spin and only to a very small extent in the 11/2- nuclear spin, the latter should not be considered further. The 7/2+ excited state transitions to the 5/2+ intermediate state by emitting a 171 keV γ-quantum. The intermediate state has a lifetime of 84 | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation 5 ns and is the sensitive state for the PAC. This state in turn decays into the 1/2+ ground state by emitting a γ-quantum with 245 keV. PAC now detects both γ-quanta and evaluates the first as a start signal, the second as a stop signal. Now one measures the time between start and stop for each event. This is called coincidence when a start and stop pair has been found. Since the intermediate state decays according to the laws of radioactive decay, one obtains an exponential curve with the lifetime of this intermediate state after plotting the frequency over time. Due to the non-spherically symmetric radiation of the second γ-quantum, the so-called anisotropy, which is an intrinsic property of the nucleus in this transition, it comes with the surrounding electrical and/or magnetic fields to a periodic disorder (hyperfine interaction). The illustration of the individual spectra on the right shows the effect of this disturbance as a wave pattern on the exponential decay of two detectors, one pair at 90° and one at 180° to each other. The waveforms to both detector pairs are shifted from each other. Very simply, one can imagine a fixed observer looking at a lighthouse whose light intensity periodically becomes lighter and darker. Correspondingly, a detector arrangement, usually four detectors in a planar 90 ° arrangement or six detectors in an octahedral arrangement, "sees" the rotation of the core on the order of magnitude of MHz to GHz | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation According to the number n of detectors, the number of individual spectra (z) results after z=n²-n, for n=4 therefore 12 and for n=6 thus 30. In order to obtain a PAC spectrum, the 90° and 180° single spectra are calculated in such a way that the exponential functions cancel each other out and, in addition, the different detector properties shorten themselves. The pure perturbation function remains, as shown in the example of a complex PAC spectrum. Its Fourier transform gives the transition frequencies as peaks. formula_1, the count rate ratio, is obtained from the single spectra by using: Depending on the spin of the intermediate state, a different number of transition frequencies show up. For 5/2 spin, 3 transition frequencies can be observed with the ratio ω+ω=ω. As a rule, a different combination of 3 frequencies can be observed for each associated site in the unit cell. PAC is a statistical method: Each radioactive probe atom sits in its own environment. In crystals, due to the high regularity of the arrangement of the atoms or ions, the environments are identical or very similar, so that probes on identical lattice sites experience the same hyperfine field or magnetic field, which then becomes measurable in a PAC spectrum. On the other hand, for probes in very different environments, such as in amorphous materials, a broad frequency distribution or no is usually observed and the PAC spectrum appears flat, without frequency response | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation With single crystals, depending on the orientation of the crystal to the detectors, certain transition frequencies can be reduced or extinct, as can be seen in the example of the PAC spectrum of zinc oxide (ZnO). In the typical PAC spectrometer, a setup of four 90° and 180° planar arrayed detectors or six octahedral arrayed detectors are placed around the radioactive source sample. The detectors used are scintillation crystals of BaF or NaI. For modern instruments today mainly LaBr:Ce or CeBr are used. Photomultipliers convert the weak flashes of light into electrical signals generated in the scintillator by gamma radiation. In classical instruments these signals are amplified and processed in logical AND/OR circuits in combination with time windows the different detector combinations (for 4 detectors: 12, 13, 14, 21, 23, 24, 31, 32, 34, 41, 42, 43) assigned and counted. Modern digital spectrometers use digitizer cards that directly use the signal and convert it into energy and time values and store them on hard drives. These are then searched by software for coincidences. Whereas in classical instruments, "windows" limiting the respective γ-energies must be set before processing, this is not necessary for the digital PAC during the recording of the measurement. The analysis only takes place in the second step | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation In the case of probes with complex cascades, this makes it makes it possible to perform a data optimization or to evaluate several cascades in parallel, as well as measuríng different probes simultaneously. The resulting data volumes can be between 60 and 300 GB per measurement. As materials for the investigation (samples) are in principle all materials that can be solid and liquid. Depending on the question and the purpose of the investigation, certain framework conditions arise. For the observation of clear perturbation frequencies it is necessary, due to the statistical method, that a certain proportion of the probe atoms are in a similar environment and e.g. experiences the same electric field gradient. Furthermore, during the time window between the start and stop, or approximately 5 half-lives of the intermediate state, the direction of the electric field gradient must not change. In liquids, therefore, no interference frequency can be measured as a result of the frequent collisions, unless the probe is complexed in large molecules, such as in proteins. The samples with proteins or peptides are usually frozen to improve the measurement. The most studied materials with PAC are solids such as semiconductors, metals, insulators, and various types of functional materials. For the investigations, these are usually crystalline. Amorphous materials do not have highly ordered structures. However, they have close proximity, which can be seen in PAC spectroscopy as a broad distribution of frequencies | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation Nano-materials have a crystalline core and a shell that has a rather amorphous structure. This is called core-shell model. The smaller the nanoparticle becomes, the larger the volume fraction of this amorphous portion becomes. In PAC measurements, this is shown by the decrease of the crystalline frequency component in a reduction of the amplitude (attenuation). The amount of suitable PAC isotopes required for a measurement is between about 10 to 1000 billion atoms (10-10). The right amount depends on the particular properties of the isotope. 10 billion atoms are a very small amount of substance. For comparison, one mol contains about 6.22x10 particles. 10 atoms in one cubic centimeter of beryllium give a concentration of about 8 nmol/L (nanomol=10 mol). The radioactive samples each have an activity of 0.1-5 MBq, which is in the order of the exemption limit for the respective isotope. How the PAC isotopes are brought into the sample to be examined is up to the experimenter and the technical possibilities. The following methods are usual: During implantation, a radioactive ion beam is generated, which is directed onto the sample material. Due to the kinetic energy of the ions (1-500 keV) these fly into the crystal lattice and are slowed down by impacts. They either come to a stop at interstitial sites or push a lattice-atom out of its place and replace it. This leads to a disruption of the crystal structure. These disorders can be investigated with PAC. By tempering these disturbances can be healed | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation If, on the other hand, radiation defects in the crystal and their healing are to be examined, unperseived samples are measured, which are then annealed step by step. The implantation is usually the method of choice, because it can be used to produce very well-defined samples. In a vacuum, the PAC probe can be evaporated onto the sample. The radioactive probe is applied to a hot plate or filament, where it is brought to the evaporation temperature and condensed on the opposite sample material. With this method, e.g. surfaces are examined. Furthermore, by vapor deposition of other materials, interfaces can be produced. They can be studied during tempering with PAC and their changes can be observed. Similarly, the PAC probe can be transferred to sputtering using a plasma. In the diffusion method, the radioactive probe is usually diluted in a solvent applied to the sample, dried and it is diffused into the material by tempering it. The solution with the radioactive probe should be as pure as possible, since all other substances can diffuse into the sample and affect thereby the measurement results. The sample should be sufficiently diluted in the sample. Therefore, the diffusion process should be planned so that a uniform distribution or sufficient penetration depth is achieved. PAC probes may also be added during the synthesis of sample materials to achieve the most uniform distribution in the sample | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation This method is particularly well suited if, for example, the PAC probe diffuses only poorly in the material and a higher concentration in grain boundaries is to be expected. Since only very small samples are necessary with PAC (about 5 mm), micro-reactors can be used. Ideally, the probe is added to the liquid phase of the sol-gel process or one of the later precursor phases. In neutron activation, the probe is prepared directly from the sample material by converting very small part of one of the elements of the sample material into the desired PAC probe or its parent isotope by neutron capture. As with implantation, radiation damage must be healed. This method is limited to sample materials containing elements from which neutron capture PAC probes can be made. Furthermore, samples can be intentionally contaminated with those elements that are to be activated. For example, hafnium is excellently suited for activation because of its large capture cross section for neutrons. Rarely used are direct nuclear reactions in which nuclei are converted into PAC probes by bombardment by high-energy elementary particles or protons. This causes major radiation damage, which must be healed. This method is used with PAD, which belongs to the PAC methods. The currently largest PAC laboratory in the world is located at ISOLDE in CERN with about 10 PAC instruments, that receives its major funding form BMBF | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation Radioactive ion beams are produced at the ISOLDE by bombarding protons from the booster onto target materials (uranium carbide, liquid tin, etc.) and evaporating the spallation products at high temperatures (up to 2000 °C), then ionizing them and then accelerating them. With the subsequent mass separation usually very pure isotope beams can be produced, which can be implanted in PAC samples. Of particular interest to the PAC are short-lived isomeric probes such as: Cd, Hg, Pb, and various rare earth probes. The first formula_3-quantum (formula_4) will be emitted isotopically. Detecting this quantum in a detector selects a subset with an orientation of the many possible directions that has a given. The second formula_3-quantum (formula_6) has an anisotropic emission and shows the effect of the angle correlation. The goal is to measure the relative probability formula_7 with the detection of formula_8 at the fixed angle formula_9 in relation to formula_10. The probability is given with the angle correlation (perturbation theory): For a formula_3-formula_3-cascade, formula_14 is due to the preservation of parity: Where formula_16 is the spin of the intermediate state and formula_17 with formula_18 the multipolarity of the two transitions. For pure multipole transitions, is formula_19. formula_20 is the anisotropy coefficient that depends on the angular momentum of the intermediate state and the multipolarities of the transition | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation The radioactive nucleus is built into the sample material and emits two formula_3-quanta upon decay. During the lifetime of the intermediate state, i.e. the time between formula_10 and formula_8, the core experiences a disturbance due to the hyperfine interaction through its electrical and magnetic environment. This disturbance changes the angular correlation to: formula_25 is the perturbation factor. Due to the electrical and magnetic interaction, the angular momentum of the intermediate state formula_17 experiences a torque about its axis of symmetry. Quantum-mechanically, this means that the interaction leads to transitions between the M states. The second formula_3-quantum (formula_8) is then sent from the intermediate level. This population change is the reason for the attenuation of the correlation. The interaction occurs between the magnetic core dipole moment formula_29 and the intermediate state formula_16 or/and an external magnetic field formula_31. The interaction also takes place between nuclear quadrupole moment and the off-core electric field gradient formula_32. For the magnetic dipole interaction, the frequency of the precession of the nuclear spin around the axis of the magnetic field formula_31 is given by: formula_36 is the Landé g-factor und formula_37 is the nuclear magneton | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation With formula_38 follows: From the general theory we get: For the magnetic interaction follows: The energy of the hyperfine electrical interaction between the charge distribution of the core and the extranuclear static electric field can be extended to multipoles. The monopole term only causes an energy shift and the dipole term disappears, so that the first relevant expansion term is the quadrupole term: This can be written as a product of the quadrupole moment formula_43 and the electric field gradient formula_44. Both [tensor]s are of second order. Higher orders have too small effect to be measured with PAC. The electric field gradient is the second derivative of the electric potential formula_45 at the core: formula_44 becomes diagonalized, that: The matrix is free of traces in the main axis system (Laplace equation) Typically, the electric field gradient is defined with the largest proportion formula_32 and formula_51: In cubic crystals, the axis parameters of the unit cell x, y, z are of the same length. Therefore: In axisymmetric systems is formula_55. For axially symmetric electric field gradients, the energy of the substates has the values: The energy difference between two substates, formula_58 and formula_59, is given by: The quadrupole frequency formula_61 is introduced. The formulas in the colored frames are important for the evaluation: The publications mostly list formula_64. formula_65 as elementary charge and formula_66 as Planck constant are well known or well defined | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation The nuclear quadrupole moment formula_67 is often determined only very inaccurately (often only with 2-3 digits). Because formula_64 can be determined much more accurately than formula_67, it is not useful to specify only formula_32 because of the error propagation. In addition, formula_64 is independent of spin! This means that measurements of two different isotopes of the same element can be compared, such as Hg(5/2−), Hg(5/2−) and Hg(9/2−). Further, formula_64 can be used as finger print method. For the energy difference then follows: If formula_55, then: with: For integer spins applies: For half integer spins applies: The perturbation factor is given by: With the factor for the probabilities of the observed frequencies: As far as the magnetic dipole interaction is concerned, the electrical quadrupole interaction also induces a precision of the angular correlation in time and this modulates the quadrupole interaction frequency. This frequency is an overlap of the different transition frequencies formula_83. The relative amplitudes of the various components depend on the orientation of the electric field gradient relative to the detectors (symmetry axis) and the asymmetry parameter formula_51. For a probe with different probe nuclei, one needs a parameter that allows a direct comparison: Therefore, the quadrupole coupling constant formula_64 independent of the nuclear spin formula_86 is introduced | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation If there is a magnetic and electrical interaction at the same time on the radioactive nucleus as described above, combined interactions result. This leads to the splitting of the respectively observed frequencies. The analysis may not be trivial due to the higher number of frequencies that must be allocated. These then depend in each case on the direction of the electric and magnetic field to each other in the crystal. PAC is one of the few ways in which these directions can be determined. If the hyperfine field fluctuates during the lifetime formula_87 of the intermediate level due to jumps of the probe into another lattice position or from jumps of a near atom into another lattice position, the correlation is lost. For the simple case with an undistorted lattice of cubic symmetry, for a jump rate of formula_88 for equivalent places formula_89, an exponential damping of the static formula_90-terms is observed: Here formula_93 is a constant to be determined, which should not be confused with the decay constant formula_94. For large values of formula_95, only pure exponential decay can be observed: The boundary case after Abragam-Pound is formula_93, if formula_98, then: Cores that transmute beforehand of the formula_3-formula_3-cascade usually cause a charge change in ionic crystals (In) to Cd). As a result, the lattice must respond to these changes. Defects or neighboring ions can also migrate | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation Likewise, the high-energy transition process may cause the Auger effect, that can bring the core into higher ionization states. The normalization of the state of charge then depends on the conductivity of the material. In metals, the process takes place very quickly. This takes considerably longer in semiconductors and insulators. In all these processes, the hyperfine field changes. If this change falls within the formula_3-formula_3-cascade, it may be observed as an after effect. The number of nuclei in state (a) in the image on the right is depopulated both by the decay after state (b) and after state (c): mit: formula_105 From this one obtains the exponential case: For the total number of nuclei in the static state (c) follows: The initial occupation probabilities formula_108 are for static and dynamic environments: In the general theory for a transition formula_111 is given: with: | https://en.wikipedia.org/wiki?curid=62421802 |
Fluorescence-activating and absorption-shifting tag FAST ("Fluorescence-Activating and absorption-Shifting Tag") is a small, genetically-encoded, protein tag which allows for fluorescence reporting of proteins of interest. Unlike natural fluorescent proteins and derivates such as GFP or mCherry, FAST is not fluorescent by itself. It can bind selectively a fluorogenic chromophore derived from 4-hydroxybenzylidene rhodanine (HBR), which is itself non fluorescent unless bound. Once bound, the pair of molecules goes through a unique fluorogen activation mechanism based on two spectroscopic changes, increase of fluorescence quantum yield and absorption red shift, hence providing high labeling selectivity. The FAST-fluorogen reporting system can be used in fluorescence microscopy, flow cytometry and any other fluorometric method to explore the living world: biosensors, protein trafficking. FAST, a small 14 kDa protein, was engineered from the photoactive yellow protein (PYP) by directed evolution. It was reported for the first time in 2016 by researchers from Ecole normale supérieure de Paris. FAST pertains to a chemical-genetic strategy for specific labeling of proteins. A peptide domain, called "tag", is genetically encoded to be bound to a protein of interest (by combination of their respective genes by means of transfection or infection). This tag is the anchor for a synthetic fluorescent probe to be further added | https://en.wikipedia.org/wiki?curid=62423839 |
Fluorescence-activating and absorption-shifting tag Such chemical-genetic approach was already implemented besides natural fluorescent proteins such as GFP or their derivatives such as mCherry in several systems already widely used: Several versions of FAST have been described differing by a small number of mutations, "e.g.", FAST1 (a.k.a. Y-FAST), FAST2 (a.k.a. iFAST), or a dimer, td-FAST. Also, a complementation split version for monitoring protein-protein interactions was developed, splitFAST. A number of plasmids displaying FAST or splitFAST genes are available at Addgene. The FAST-fluorogen reporting system is used in fluorescence microscopy, flow cytometry and any other fluorometric methods to explore the living world: biosensors, protein trafficking. FAST has been reported for dynamic imaging of biofilms thanks to its unique capacity of fluoresceing in low-oxygen conditions. For the same reason it allows for imaging and FACSing anaerobes, such as "Clostridium", used for biomass fermentation like the ABE fermentation. FAST has also been reported for super-resolution microscopy of living cells. A number of fluorogens were developed for FAST and its derivates by The Twinkle Factory, varying by their emission wavelength, their brightness and their tag affinity. Some are non permeant, "i.e.", they can't go through cell membranes, hence specifically labeling membrane proteins or extracellular proteins, allowing for, "e.g.", monitoring trafficking from synthesis until excretion. | https://en.wikipedia.org/wiki?curid=62423839 |
Sandrine Heutz is a Professor of Functional Molecular Materials at Imperial College London. She works on organic and magnetically coupled molecular materials for spintronic applications. In 2008 Heutz was awarded the Institute of Materials, Minerals and Mining Silver Medal. Heutz studied chemistry at the University of Liège. She moved to Imperial College London for her doctoral studies, where she worked on thin film heterostructures. During her doctoral research Heutz worked with Dietrich Zahn at Chemnitz University of Technology. After earning her postgraduate degree Heutz worked as a postdoctoral fellow on solar cells at Imperial College London. She moved to University College London in 2004, where she started work on magnetic biosensors. Heutz joined Imperial College London in 2007 as a Royal Society Dorothy Hodgkin Research Fellow. She was awarded the 2008 Institute of Materials, Minerals and Mining Silver Medal for her research on organic thin films. In particular she had developed new electron - donor morphologies for efficient solar cells. Heutz specialises in the use of electron paramagnetic resonance (EPR) to monitor unpaired electrons within materials. She used EPR to monitor spins within copper phthalocyanine solar cells. Whilst working on new materials for photovoltaics, Heutz showed that electrons in copper phthalocyanine (a blue pigment found in a Bank of England £5 note) exist in a superposition of two different spin states | https://en.wikipedia.org/wiki?curid=62431193 |
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