Novel telechelic olefin and hydroxy polymers particularly those of polyisobutylene are prepared according to the process set forth herein. Preparation of a telechelic diolefin polyisobutylene includes the steps of refluxing a solution of telechelic dihalogen polyisobutylene, adding a solution of a strong base such as potassium t-butoxide and stirring to form the telechelic diolefin polyisobutylene. This telechelic diolefin can be converted to the telechelic dihydroxy by refluxing a solution of the former, hydroborating the diolefin to a polymeric borane and oxidizing the polymeric borane to form the telechelic dihydroxy polyisobutylene. The processes are also applicable to the conversion of trihalogenated polyisobutylenes to telechelic triolefin and trihydroxy polyisobutylene tristars.
TY - JOUR. T1 - The wacker process. T2 - Inner- Or outer-sphere nucleophilic addition? New insights from Ab initio molecular dynamics. AU - Comas-Vives, Aleix. AU - Stirling, András. AU - Lledós, Agustí. AU - Ujaque, Gregori. PY - 2010/8/2. Y1 - 2010/8/2. N2 - The Wacker process consists of the oxidation of ethylene catalyzed by a PdII complex. The reaction mechanism has been largely debated in the literature; two modes for the nucleophilic addition of water to a Pd-coordinated alkene have been proposed: syninner- and anti-outer-sphere mechanisms. These reaction steps have been theoretically evaluated by means of ab initio molecular dynamics combined with metadynamics by placing the [Pd-(C2H 4)Cl2(H2O)] complex in a box of water molecules, thereby resembling experimental conditions at low [Cl-]. The nucleophilic addition has also been evaluated for the [Pd(C 2H4)Cl3]- complex, thus revealing that the water by chloride ligand substitution trans to ethene is kinetically favored over the ...
Using density functional theory and Ab Initio Molecular Dynamics with Electronic Friction (AIMDEF), we study the adsorption and dissipative vibrational dynamics of hydrogen atoms chemisorbed on free-standing lead films of increasing thickness. Lead films are known for their oscillatory behaviour of certain properties with increasing thickness, e.g., energy and electron spillout change in discontinuous manner, due to quantum size effects [G. Materzanini, P. Saalfrank, and P. J. D. Lindan, Phys. Rev. B 63, 235405 (2001)]. Here, we demonstrate that oscillatory features arise also for hydrogen when chemisorbed on lead films. Besides stationary properties of the adsorbate, we concentrate on finite vibrational lifetimes of H-surface vibrations. As shown by AIMDEF, the damping via vibration-electron hole pair coupling dominates clearly over the vibration-phonon channel, in particular for high-frequency modes. Vibrational relaxation times are a characteristic function of layer thickness due to the ...
A fundamental quantum mechanical modelling approach is used for calculating liquid diffusion parameters in cemented carbides. Up to now, no detailed description of diffusion for alloying elements in a liquid Co matrix is available. Neither are experimental measurements found in the literature for the self- or impurity diffusion in the liquid Co system. State of the art application is the description of gradient formation in cemented carbide systems using DICTRA. In this work it is assumed that diffusion during sintering of cemented carbides takes place mainly in the liquid Co binder phase. With this assumption one can calculate the diffusion coefficient for different alloying elements like W, Ti, N and C in a liquid Co matrix phase. The mean square displacement (MSD) of the diffusing atoms is used to obtain the diffusion coefficients which could be simulated by Ab initio Molecular Dynamics (AIMD). By fitting the computed temperature dependence with the Arrhenius relation one can determine the ...
This website uses cookies to deliver some of our products and services as well as for analytics and to provide you a more personalized experience. Click here to learn more. By continuing to use this site, you agree to our use of cookies. Weve also updated our Privacy Notice. Click here to see whats new. Allow All Cookies ...
in Physical Review Letters (2005), 95(26), 2678011-26780142678014. The density anomaly of liquid Ge 0.15Te 0.85 measured between 633 and 733 K is investigated with ab initio molecular dynamics calculations at four temperatures and at the corresponding experimental ... [more ▼]. The density anomaly of liquid Ge 0.15Te 0.85 measured between 633 and 733 K is investigated with ab initio molecular dynamics calculations at four temperatures and at the corresponding experimental densities. For box sizes ranging from 56 to 112 atoms, an 8 k-points sampling of the Brillouin zone is necessary to obtain reliable results. Contrary to other Ge chalcogenides, no sp 3 hybridization of the Ge bonding is observed. As a consequence, the negative thermal expansion of the liquid is not related to a tetrahedral bonding as in the case of water or silica. We show that it results from the symmetry recovery of the local environment of Ge atoms that is distorted at low temperature by a Peierls-like mechanism acting in ...
Close The Infona portal uses cookies, i.e. strings of text saved by a browser on the users device. The portal can access those files and use them to remember the users data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser. ...
Vanadium dioxide (VO2), with a reversible phase transition near ambient temperature, has been found to be a promising candidate for energy-saving smart windows. However, its use is constrained by its low visible transmission (Tlum) and high transition temperature (τc). In this paper, by codoping tungsten (W) and magnesium (Mg) in VO2, a good combination of low τc (~35 °C) and high Tlum (81.3%) was achieved. The τc declines with decreasing Mg doping level in Mg/W-codoped samples, which is the opposite effect of doping with only Mg, suggesting a synergistic effect of the two dopants arising from the e− and h+ carrier neutralization. In addition, the band gap of Mg/W-codoped VO2 was gradually widened; this is attributed to the depressed absorption, which enhanced the Tlum ...
A study was conducted to deter ine the mathematical form of the theory for unsteady diffusion processes in ter s of specifically related physical concepts, mainly those of mechanics and thermodynamics. A mathematical model was developed for unsteady rapid expansion of a nonreacting binary inviscid mixture of perfect gases in which diffusion occurs. The analysis is based on Prigogines method, which utilizes the concept of generalize flow. The derived equations depend on influence coefficients which can be related to a diffusion coefficient. Since the derivation is limited to macroscopic concepts, any diffusion which results in a macroscopically measurable change in gas mixture composition is admissible, whether it be molecular or turbulent. The final form of the model is similar to those of Prigogine, Chapman and Cowling, or DeGroot. However, the diffusion coefficient as discussed is slightly different and chemical reactions are excluded. (Author)*FLUID MECHANICS
Unauthorized use of any materials presented here is prohibited. Copying or reproducing any elements from this page is not permitted. All prices, descriptions and availability subject to change ...
Towards more realistic molecular modeling of catalysis with density functional theory: Combined QM/MM and ab initio molecular dynamics ...
Starting from common monounsaturated fatty acids, a strategy is revealed that provides ultra-long aliphatic α,ω-difunctional building blocks by a sequence of two scalable catalytic steps that virtually double the chain length of the starting materials. The central double bond of the α,ω-dicarboxylic fatty acid self-metathesis products is shifted selectively to the statistically much-disfavored α,β-position in a catalytic dynamic isomerizing crystallization approach. "Chain doubling" by a subsequent catalytic olefin metathesis step, which overcomes the low reactivity of this substrates by using waste internal olefins as recyclable co-reagents, yields ultra-long-chain α,ω-difunctional building blocks of a precise chain length, as demonstrated up to a C,sub,48,/sub, chain. The unique nature of these structures is reflected by unrivaled melting points (T,sub,m,/sub, =120 °C) of aliphatic polyesters generated from these telechelic monomers, and by their self-assembly to polyethylene-like ...
The ,-stabilized carbanion complexes [PhSO2CHCNNa·THF], 3, [t-BuSO2CHCNNa], 4, [PhSO2CHCNK], 5, [t-BuSO2CHCNK], 6, and [MeSO2CHCNLi·TMEDA], 7, have been synthesized via the metalation of the parent (organo)sulfonylacetonitriles by BuLi, BuNa, or BnK in THF solution (or THF/TMEDA in the case of 7). In addition, complexes 3 and 7 have been characterized by single-crystal X-ray analyses and have been found to adopt related structures in the solid state. Complex 7 is a molecular dimer containing a central 12-membered (OSCCNLi)2 ring core, with each metal rendered tetracoordinate by binding to a chelating TMEDA molecule. As found in related complexes, no direct carbanion to lithium contacts are present in the structure of 7. Complex 3 forms a polymeric cage structure composed of associated dimeric (OSCCNNa)2 rings, similar to those found in 7. The larger sodium cations, and the presence of only one THF molecule/metal, allow additional contacts with the anions, leading to hexacoordination at the ...
SYDNEY: The worlds thinnest material can shed light on the exact measurement of one of the universes fundamental physical constants, a new study reveals.. Researchers led by physicist Andre Geim from the University of Manchester in the U.K., used graphene - a sheet of carbon just one atom thick - to gauge the exact measurement of the fine structure constant, a fundamental physical constant defining the interaction between fast moving electric charges and light.. Their results were published online in the current edition of the journal Science Express, ahead of publication in the U.S. journal Science. The fine structure constant was first introduced by physicists in attempts to understand atomic structure and has long mystified scientists because there seemed to be no natural mathematical relationship that described the constant, like a circles circumference divided by its diameter describes the universal constant pi.. Foundations of life. In this new study, the U.K. and Portuguese researchers ...
Scientific American is the essential guide to the most awe-inspiring advances in science and technology, explaining how they change our understanding of the world and shape our lives.
184] Zheshuai Lin, L. F. Xu, R. K. Li, Zhizhong Wang, Chuangtian Chen, Ming-Hsien Lee, E. G. Wang? and Ding-sheng Wang?Phys. Rev. B 70, 233104 (2004), "Ab initio study of the hygroscopic properties of borate crystals" PDF. [183] S. Meng, E.G. Wang, and S.W. Gao, J. Phys. Conden. Mett. 16, 8851(2004), "The pressure induced phase transition of confined water from ab initio molecular dynamics simulation". PDF. [182] Y. Guo, Y.F. Zhang, X.Y. Bao, T.Z. Han, Z. Tang, L.X. Zhang, W.G. Zhu, E.G. Wang, Q. Niu, Z.Q. Qiu, J.F. Jia, Z.X Zhao, and Q.K. Xue, Science 306, 1915(2004), "Superconductivity modulated by quantum size effects". (Highlighted as Perspectives in Science 306, 1900 (2004) and This Week in Science (2004) PDF. [181] C.Y. Zhi, X.D. Bai, and E.G. Wang, Appl. Phys. Lett. 85, 1802(2004) "Synthesis of semiconductor nanowires by annealing".(Selected in Virtual J. Nanoscale Science & Technology, Sept. 27, 2004 issue) PDF. [180] N. Y. Huang, J. C. She, Jun Chen, S. Z. Deng, N. S. Xu, H. Bishop, S. ...
Amorphous alloys of aluminum nitride and gallium nitride deposited at 100 K at compositions ranging from pure AlN to pure GaN with optical band gaps which vary linearly with composition from 3.27 eV (a-GaN) to 5.95 eV (a-AlN) have been synthesized. Ab initio molecular dynamics calculations for these alloys reproduce the band gap versus composition data and give specific information on the electronic localization of the band tail states. There are no midgap states in amorphous Al[sub x]Ga[sub 1-x]N alloys. The calculated models have mixed four-fold and three-fold coordination and have no wrong (homopolar nuclear) bonds, demonstrating the strong ionicity in amorphous Al[sub x]Ga[sub 1-x]N alloys. It has been found that the valence band tail states are mostly localized on the three-fold coordinated N sites while the conduction band tail states are mostly localized on the three-fold coordinated Ga or Al sites. © 2000 American Institute of Physics ...
Ab initio Molecular Dynamics simulations and static Density Functional Theory calculations have been performed to investigate the reaction mechanism of CO oxidation on Au/CeO 2 catalyst. It is found that under reaction condition CO adsorption significantly labializes the surface atoms of the Au cluster and leads to the formation of isolated Au+-CO species that resides on the support in the vicinity of the Au particle. In this context, we identified a dynamic single-atom catalytic mechanism at the interfacial area for CO oxidation on Au/CeO 2 catalyst, which is a lower energy pathway than that of CO oxidation at the interface with the metal particle. This results from the ability of the single atom site to strongly couple with the redox properties of the support in a synergistic manner thereby lowering the barrier for redox reactions. We find that the single Au+ ion, which only exists under reaction conditions, breaks away from the Au cluster to catalyze CO oxidation and returns to the Au cluster ...
Microscopic processes leading to ultrafast laser-induced melting of silicon are investigated by large-scale ab initio molecular dynamics simulations. Before becoming a liquid, the atoms are shown to be fractionally diffusive, which is a property that has so far been observed in crowded fluids consisting of large molecules. Here, it is found to occur in an elemental semiconductor. ...
Innovative services for materials design. SIMUNE is a company expert in atomistic simulations that helps leading R&D groups save cost and time, and accelerate the whole materials design process in a variety of applications such as semiconductors, energy storage, catalysis and other technological applications. SIESTA is both a method and its computer program implementation, to perform efficient electronic structure calculations and ab initio molecular dynamics simulations of molecules and solids. SIESTA is under continuous development since it was first published and is currently used by thousands of scientists worldwide. ...
Innovative services for materials design. SIMUNE is a company expert in atomistic simulations that helps leading R&D groups save cost and time, and accelerate the whole materials design process in a variety of applications such as semiconductors, energy storage, catalysis and other technological applications. SIESTA is both a method and its computer program implementation, to perform efficient electronic structure calculations and ab initio molecular dynamics simulations of molecules and solids. SIESTA is under continuous development since it was first published and is currently used by thousands of scientists worldwide. ...
... Roger G. Lentle, Patrick W.M. Janssen Publisher: 2011 | 288 Pages | ISBN: 1441994483 | PDF | 12 MB This book is aimed at physiologists, pharmacologists, nutritionists and food technologists whose work requires an understanding of the physical processes of digestion.
Motivation: Template-based prediction of DNA binding proteins requires not only structural similarity between target and template structures but also prediction of binding affinity between the target and DNA to ensure binding. Here, we propose to predict protein- DNA binding affinity by introducing a new volume-fraction correction to a statistical energy function based on a distance-scaled, finite, ideal-gas reference (DFIRE) state. Results: We showed that this energy function together with the structural alignment program TM-align achieves the Matthews correlation coefficient (MCC) of 0.76 with an accuracy of 98%, a precision of 93% and a sensitivity of 64%, for predicting DNA binding proteins in a benchmark of 179 DNA binding proteins and 3797 nonbinding proteins. The MCC value is substantially higher than the best MCC value of 0.69 given by previous methods. Application of this method to 2235 structural genomics targets uncovered 37 as DNA binding proteins, 27 (73%) of which are putatively ...
PubMed comprises more than 30 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.
For this purpose the air of the reference atmosphere is conveyed with a constant volume flow rate through a combined mesh-filter probe. The fraction of the short-lived radon-222 progenies, which are attached to aerosols, are deposited to the filter. The free (unattached) fraction is adsorbed to the wire mesh.. The activity collected at the filter and the mesh, respectively, decays according to the radioactive decay law. The activities of the alpha-emitting nuclides are measured in periodic time intervals. The associated graphic representation is denominated as decay curve.. Immediately after sampling the decay curves of the filter and mesh alpha activity are measured, respectively. An algorithm is used to deduce the potential alpha-energy concentration and unattached part of the short-lived radon-222 progenies. ...
For this purpose the air of the reference atmosphere is conveyed with a constant volume flow rate through a combined mesh-filter probe. The fraction of the short-lived radon-222 progenies, which are attached to aerosols, are deposited to the filter. The free (unattached) fraction is adsorbed to the wire mesh.. The activity collected at the filter and the mesh, respectively, decays according to the radioactive decay law. The activities of the alpha-emitting nuclides are measured in periodic time intervals. The associated graphic representation is denominated as decay curve.. Immediately after sampling the decay curves of the filter and mesh alpha activity are measured, respectively. An algorithm is used to deduce the potential alpha-energy concentration and unattached part of the short-lived radon-222 progenies. ...
Three science-oriented U.S. philanthropies have come together to award grants to six teams comprised of 15 individual investigators -- $963,750 in all -- probing fundamental physical processes at the cellular level essential to living organisms. The research teams were formed in April during Scialog: Molecules Come to Life, a cross-disciplinary conference with a unique format focused on science dialog, sponsored by the Gordon and Betty Moore Foundation and Research Corporation for Science Advancement. Additional funding is being provided by the Simons Foundation. "Scialog aims to encourage collaborations between theorists and experimentalists," said RCSA Senior Program Director Richard Wiener. "And, we want to catalyze the development of a community in which theory informs experiment, with both working together to achieve understanding of fundamental cellular processes.". In the process, Scialog Fellows work toward the goals of identifying bottlenecks and finding avenues for breakthroughs, added ...
Solved Problems on Thermodynamics:-Problem 1:-A container holds a mixture of three nonreacting gases: n 1 moles of the first gas with molar specific heat at constant volume C 1, and so on.Find the molar specific heat at constant volume of the mixture, in terms of the molar specific heats and quantitites of the three separate gases.. ...
Solvent cement the 1" diameter short pipe and ring into the bored hole in the large pressure chamber endcap. NOTE - after 9/15/05 this short pipe is supplied using the stronger schedule 80 material. It is dark grey rather than the usual white PVC. It is installed using the same procedure and cement as before. (Depending on your parts it might be a slightly different length. It should fill the coupler ring, the endcap and have enough left sticking out to fully fill the valve socket - 3/4". See the cut schedule above for details). This joint holds full pressure for extended periods so it is imortant that it be a good joint. Prepare the endcap, masking it on the inside to protect the inside vertical glueing surfaces to be used later for the pressure chamber pipe. Position the 1" pipe so it extends into the endcap about 1/3 of an inch. There should be 0.75" of the pipe sticking out of the endcap to fit the socket in the sprinkler valve. (This may need to be adjusted depending on your particular ...
After a recent hospital stay for a complex infection I developed 2 large pressure sores mStage 3 and other one possibly Stage 4 we have been unsuccessful in the last 2 weeks since my discharge to set up any kind of regular home health care The best scenario for home health in my area is a r.andom hour maybe twice a week no regular times etc. essentially no help and insurance wouldn?t cover it anyway. There are no. Pca type services offered so Basically it?s either my wife or the nursing My
In the reaction $\ce{N2 (g) + O2(g) -, 2NO (g)}$ my textbook[1] says $q_v$ and $q_p$ are not the same, without any explanation.. I know that \begin{align} \Delta U &= q_p + w\\ \Delta U &= q_p - P\Delta V\\ \Delta U &= q_p - Δn_\mathrm{gases}RT \end{align}. I also know that $$\Delta U = q_v.$$. because under constant volume, work done ($-P\Delta V$) is zero, since theres no change in volume. In the reaction mentioned, $$n_\mathrm{gases} = 0,$$ so ...
E-mail address: [email protected] (Received November 1, 2011; Accepted March 11, 2012) Abstract. Aggregation patterns in the volume-filling Keller-Segel model are studied numerically. Three-dimensional specific patterns, such as P-surface, perforated lamellar, are appeared. These patterns never exist in lower dimensions. The relative stability analysis of these patterns is also performed numerically on the basis of the derived free energy and of the robustness against perturbation. Keywords: Chemotaxis, Keller-Segel Model, Pattern Selection, Stability Analysis ...
molar gas constant: (symbol R), fundamental physical constant arising in the formulation of the general gas law. For an ideal gas (approximated by most real gases that are not highly compressed or...
This is a conceptual General Education lecture/activity course with much opportunity for discussion. The course provides an overview of modern physical theory, emphasizing the approach of science in understanding our place in the universe. The student discovers how simple, fundamental physical principles enable us to understand key features in diverse physical systems: from the radiometric dating of early hominid ancestors to the measurement of the expansion rate of the Universe. The course emphasizes our current understanding of solar system formation, stellar evolution, and cosmic evolution. This in turns leads us to investigate the physical conditions salient to life on Earth, and ways in which these conditions are rare. 2 hours discussion, 2 hours activity. This is an approved General Education course. (021079) ...
With current limitations and trends in computing, it will be decades before researchers will be able to run even primitive simulations of the universe. But the UW team has suggested tests that can be performed now, or in the near future, that are sensitive to constraints imposed on future simulations by limited resources.. Currently, supercomputers using a technique called lattice quantum chromodynamics and starting from the fundamental physical laws that govern the universe can simulate only a very small portion of the universe, on the scale of one 100-trillionth of a meter, a little larger than the nucleus of an atom, said Martin Savage, a UW physics professor.. …. However, Savage said, there are signatures of resource constraints in present-day simulations that are likely to exist as well in simulations in the distant future, including the imprint of an underlying lattice if one is used to model the space-time continuum.. The supercomputers performing lattice quantum chromodynamics ...
We have recently derived new results for dispersion, induction, and hyperpolarization forces, using nonlocal polarizability densities to characterize the changes in electronic charge density induced by molecular interactions. In this work, we prove that the fundamental physical requirement of force balance for two interacting molecules A and B is satisfied within the nonlocal response theory, order by order. An explicit proof is needed because of differences in the molecular properties that determine the forces on A and B. For example, at first order the force on A depends on the polarizability density of A, αA(r,r’;ω=0), while the first-order force on B depends on its polarizability density; and for distinct species A and B, there is no relation between αA(r,r’;ω=0) and αB(r,r’;ω=0). We show that force balance is derivable from a condition that we term ‘‘force relay.’’ Epstein has previously derived this condition for molecules ...
Each of these changes was made because the precision with which we could make the measurements became greater than the precision with which we could realize, or make use of, the previous definition. Today, we choose definitions based on fundamental physical constants and atomic properties because they provide more stable and universally available standards. They may also generally be measured relatively easily and with high precision. Each change of definition is chosen to maintain unchanged the previous value of the standard, to the accuracy with which it had previously been known.. It is important to note that the effect of each new definition is to set a fixed value for some relevant constant. Thus, the present definition of the second sets the value of the frequency of the caesium transition to be exactly 9,192,631,770 Hertz, and the present definition of the metre sets the speed of light to be exactly 299,792,458 metres per second. The 1793 definition of the metre set the distance from the ...
Advanced spectroscopic studies of quantum and novel behaviour in electronic materials and devices. The aim of my work is elucidate the fundamental physical mechanisms which underlie the operation of electronic devices, leading to improvements in device operation. This is achieved through innovative, state of the art materials characterisation and optical spectroscopy facilities.. At present the main areas of my work are:. ...
Praise for the previous edition:. "...well-developed...clear and detailed...useful at the secondary level in health and anatomy classes and for research...Recommended."-Library Media Connection. Breathing is essential to human survival, as it gives us the necessary oxygen we need to live. Yet the act of respiration is an involuntary process, something many people dont think about on a day-to-day basis. The Respiratory System, Second Edition explains how we get air into our lungs, how our bodies use that air, and the fundamental physical and biological principles underlying respiratory function. In addition, this essential title examines several respiratory diseases and how they affect the body as a whole. Packed with full-color photographs and illustrations, this absorbing book provides students with sufficient background information through references, websites, and suggested reading for further study.. ...
Increase your science IQ with a cool science fact sent to your email each workday. From cloning to nanotechnology and from global warming to fundamental physical principles: interesting, relevant and comprehensive science facts for curious minds 5 to 105 years old.
Increase your science IQ with a cool science fact sent to your email each workday. From cloning to nanotechnology and from global warming to fundamental physical principles: interesting, relevant and comprehensive science facts for curious minds 5 to 105 years old.
Hot air rises. By working with this fundamental physical principle, there are several ways to ensure that your roof is well ventilated all year round. In the su
Ballard, Glenn and Koskela, Lauri (2009) Design is a physical process too. In: DS 58-2: Proceedings of ICED 09. IECD, pp. 251-262. ISBN 978-1-904670-06-3 Metadata only available from this repository ...
RTX proteins are composed of a repeating nonamer calcium binding sequence. Often times for repeating protein scaffolds, consensus design is used to create synthetic peptides based on the amino acid frequency at each position. This can lead to higher levels of stability and recombinant expression. The genetic information can also be optimized for easier cloning and concatenation strategies. In exploring consensus design for the RTX protein, we discovered a synthetic sequence that undergoes a reversible phase change in response to calcium binding. We have used this sequence as a non-chromatographic protein purification tag, similar to the elastin like peptide (ELP) tags. By appending the β-roll tag (BRT) to a protein of interest, we can rapidly and efficiently separate the fusion from cell lysate (~ 10 minutes). We have added a protease site between the BRT and protein of interest allowing for the purification of untagged target by precipitation cycling. The image below shows the calcium ...
RTX proteins are composed of a repeating nonamer calcium binding sequence. Often times for repeating protein scaffolds, consensus design is used to create synthetic peptides based on the amino acid frequency at each position. This can lead to higher levels of stability and recombinant expression. The genetic information can also be optimized for easier cloning and concatenation strategies. In exploring consensus design for the RTX protein, we discovered a synthetic sequence that undergoes a reversible phase change in response to calcium binding. We have used this sequence as a non-chromatographic protein purification tag, similar to the elastin like peptide (ELP) tags. By appending the β-roll tag (BRT) to a protein of interest, we can rapidly and efficiently separate the fusion from cell lysate (~ 10 minutes). We have added a protease site between the BRT and protein of interest allowing for the purification of untagged target by precipitation cycling. The image below shows the calcium ...
An ideal gas at 300 K and 1.5x10^5 Pa is contained in a piston cylinder device. The piston is 0.1m above the base of the cylinder, has a diameter of 0.15 m and is allowed to move freely. Heat is transferred to the cylinder causing the piston to move a distance of 0.05 m. The gas specific heat at constant volume is 718 J/kg·K and the gas constant is 287 J/kg·K ...
A lance having an outer tube (10) and a second tube (20) slidingly mounted inside the outer tube (10) and enabling the oxygen enrichment of a flow of fuel in the form of solid particles entrained by a carrier gas through one or more over ...
Sulfur (3.26 g) is burned in a constant volume calorimeter with excess O2(g). The temperature increases from 21.25°C to 28.22°C. The bomb has a heat capacity of 923 J/K, and the calorimeter contains 815 g of water. Calculate ΔU ...
Most of the models involving microscopic physical processes in electrical ageing and degradation and breakdown have very little experimental background and
Basically, this is the idea is that a lot of the physical processes and relationships that happened in Earths past are generally the SAME as they are today. So, we look for critters that appear SIMILAR today... Because its possible the same physical forces may have influenced their appearance and body shape (and giving us insight into Sphaeraster ...