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Cytochrome c peroxidase was isolated from Paracoccus denitrificans and purified to homogeneity in three steps prior to crystallization. Two different diffraction-quality crystal forms were obtained by the hanging-drop vapour-diffusion method using a number of screening conditions. The best (needle-shaped) crystal form is suitable for structural studies and was grown from solutions containing 20% PEG 8000, 0.1 M Tris pH 8.5 and 0.2 M MgCl(2). Crystals grew to a maximum length of approximately 0.7 mm and belong to the primitive monoclinic space group P2(1), with unit-cell parameters a = 78.3, b = 51.0, c = 167.2 A, beta = 97.9 degrees. After a dehydration step and extensive optimization of the cryocooling conditions, a complete data set was collected to 2.2 A from a native crystal of the fully oxidized form of the enzyme using synchrotron radiation.
The quality of a crystallization process greatly influences the quality of the final product. Our new white paper introduces you to the fundamentals of crystallization and provides guidance for the design of a high quality crystallization process.
Upon release from the stable complex formed with its antitoxin VapB, the toxin VapC (MvpT) of the Gram-negative pathogen Shigella flexneri is capable of globally down-regulating translation by specifically cleaving initiator tRNA(fMet) in the anticodon region. Recombinant Shigella flexneri VapC(D7A) harbouring an active-site mutation was overexpressed in Escherichia coli, purified to homogeneity and crystallized by the vapour-diffusion technique. A preliminary X-ray crystallographic analysis shows that the crystals diffracted to at least 1.9 Å resolution at a synchrotron X-ray source and belonged to the trigonal space group in the hexagonal setting, H3, with unit-cell parameters a = b = 120.1, c = 52.5 Å, α = β = 90, γ = 120°. The Matthews coefficient is 2.46 Å(3) Da(-1), suggesting two molecules per asymmetric unit and corresponding to a solvent content of 50.0 ...
Purification, circular dichroism analysis, crystallization and preliminary X-ray diffraction analysis of the F plasmid CcdB killer protein ...
The transformation from a fluid to a crystal can be complicated and involve one or more precursors. Such multistep crystallization pathways occur in many chemical and physical systems, and the driving force for the appearance of the precursors has been explained by unique characteristics of the interactions among the systems building blocks. We investigated multistep crystallization pathways in hard particles, where interaction is dictated solely by building-block shape and thus entropy. We categorized multistep crystallization pathways based on the dimension of the prenucleation motifs, and discuss possible comparisons to other crystallization processes.. ...
My research into crystallization processes in magma chambers has involved investigation of both natural and artificial magmatic systems. Artifical magmas, such as those produced by In-Situ Vitrification allow a unique window into the crystallization processes of magma, as does investigation of crystals forming in the active lava lake of Mount Erebus, Antarctica REFERENCES:. DUNBAR, N.W., CASHMAN, K.V., AND DUPRE, R., 1994. Crystallization processes of anorthoclase phenocrysts in the Mt. Erebus magmatic system: Evidence from crystal composition, crystal size distributions and volatile contents of melt inclusions. In: Volcanological Studies of Mount Erebus. Antarctic Research Series, 66, 129-146. ABSTRACT. DUNBAR, N.W., JACOBS, G.K. AND NANEY, M.T., 1995. Crystallization processes in an artificial magma: variations in crystal shape, growth rate and composition with melt cooling history. Contrib. Mineral. Petrol. 120, 412-425. ABSTRACT. JACOBS, G.K., DUNBAR, N.W., NANEY, M.T., and WILLIAMS, R.T., ...
Anni presents a wealth of insight and information on the Crystallization Process and how it can potentially impact us on the journey to becoming fully fledged Crystal Humans. There is also real magic and crystal energy at work through the pages of "The Crystal Human and the Crystallization Part I" and "The Crystal Human and the Crystallization Part II". Reviewing these two books triggered my own crystallisation journey, and fortunately the relevant guidance was to hand as I worked my way through the books".. June McGuire - Management Consultant and Holistic Therapist. ...
TY - JOUR. T1 - Molecular dynamics study on external field induced crystallization of amorphous argon structure. AU - Park, Seungho. AU - Cho, Sung San. AU - Lee, Joon Sik. AU - Choi, Young Ki. AU - Kwon, Ohmyoung. PY - 2004/11. Y1 - 2004/11. N2 - A molecular dynamics study has been conducted on an external-force-field- induced isothermal crystallization process of amorphous structures as a new low-temperature athermal crystallization process. An external cyclic-force field with a dc bias is imposed on molecules selected randomly in an amorphous-phase of argon. Multiple peaks smoothed out in the radial distribution functions for amorphous states appear very clearly during the crystallization process that cannot be achieved otherwise. When the amorphous material is locally exposed to an external force field, crystallization starts and propagates from the interfacial region and crystallization growth rates can be estimated.. AB - A molecular dynamics study has been conducted on an ...
The study of proteins involved in de novo biosynthesis of purine nucleotides is central in the development of antibiotics and anticancer drugs. In view of this, a protein from the hyperthermophile Pyrococcus horikoshii OT3 was isolated, purified and crystallized using the microbatch method. Its primary structure was found to be similar to that of SAICAR synthetase, which catalyses the seventh step of de novo purine biosynthesis. A diffraction-quality crystal was obtained using Hampton Research Crystal Screen II condition No. 34, consisting of 0.05 M cadmium sulfate hydrate, 0.1 M HEPES buffer pH 7.5 and 1.0 M sodium acetate trihydrate, with 40%(v/v) 1,4-butanediol as an additive. The crystal belonged to space group P3(1), with unit-cell parameters a = b = 95.62, c = 149.13 angstrom. Assuming the presence of a hexamer in the asymmetric unit resulted in a Matthews coefficient (V-M) of 2.3 angstrom(3) Da(-1), corresponding to a solvent content of about 46%. A detailed study of this protein will ...
Adherent and pin-hole free amorphous Sb2Te3 thin films have been obtained by vacuum evaporation at substrate temperatures ≤25 °C. The films have been crystallized by thermal and laser annealing, and the crystallization processes monitored as a function of annealing temperature and laser scan speed. A comparative study of topography reveals disk-shaped crystallized areas in thermal crystallization and dendrite growth in the laser induced process. The crystallized films in both cases contain a single Sb2Te3 phase. Activation energy of 2 eV for crystallization, determined using differential scanning calorimetery indicates good room temperature stability of the amorphous states ...
Journal Article: Preliminary X-ray diffraction analysis of CfaA, a molecular chaperone essential for the assembly of CFA/I fimbriae of human enterotoxigenic Escherichia coli ...
Pengju Pan, Jianna Bao, Xiaohua Chang, Ruoxing Chang, Guorong Shan, Yongzhong Bao. State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027, P. R. China.. Supramolecular polymers (SMPs) have different crystallization behavior from conventional polymers. Crystallization of SMPs occurs in a "confined" and "dynamic" manner. Because of the reversible and stimuli-responsive natures of non-covalent bonds in SMPs, crystalline structure and crystallization kinetics of SMPs depend strongly on crystallization conditions (e.g., crystallization temperature, Tc). This offers a feasible way to tune the physical properties and functions of SMPs in processing. We first selected the 2-ureido-4[1H]-pyrimidione (UPy)-bonded poly(L-lactic acid) (PLLA) as a model SMP and investigated the crystallization kinetics, polymorphic crystalline structure, and phase transition of supramolecular PLLAs (SM-PLLAs). Crystallization rate and ...
The laboratory of Chemistry of Biological Processes is equipped with state of the art devices for the crystallization of biological macromolecules. The laboratory houses a Mosquito® Crystal (TTPLabtech) that allows the automated screening of crystallization conditions using low sample volumes and zero cross-contaminations. The robot allows the setup of sitting and hanging drop vapor diffusion trials and can perform microbatch under oil if desired. Our laboratory also owns a 5-head Dragonfly® (TTPLabtech) as a companion for the Mosquito®, which allows the setup of crystallizations screens for crystal optimization. To check the crystallization experiments, two stereomicroscopes are available including a LEICA M205C equipped with a camera IC80 HD. ...
The nonisothermal crystallization kinetics was investigated by differential scanning calorimetry for the nylon 6/graphene composites prepared by in situ polymerization. The Avrami theory modified by Jeziorny, Ozawa equation, and Mo equation was used to describe the nonisothermal crystallization kinetics. The analysis based on the Avrami theory modified by Jeziorny shows that, at lower cooling rates (at 5, 10, and 20 K/min), the nylon 6/graphene composites have lower crystallization rate than pure nylon 6. However, at higher cooling rates (at 40 K/min), the nylon 6/graphene composites have higher crystallization rate than pure nylon 6. The values of Avrami exponent m and the cooling crystallization function F(T) from Ozawa plots indicate that the mode of the nucleation and growth at initial stage of the nonisothermal crystallization may be as follows: two-dimensional (2D), then one-dimensional (1D) for all samples at 5-10 °C/min; three-dimensional (3D) or complicated than 3D, then 2D and 1D at ...
20Li(2)O-80TeMO(2) glasses were heat annealed at different temperatures between T-g and T-x and studied by using XRD, FTIR spectroscopy and DSC techniques to understand the crystallization kinetics in this glass matrix. The infrared band structure of this glass is similar to what was observed in glassy TeO2. XRD results reveal the presence of three distinct crystalline gamma-TeO2, alpha-TeO2 and Li2Te2O5 phases during the crystallization process. This is a first report of gamma-TeO2 phase crystallization in this glass matrix. DSC results confinn the crystallization of three distinct structures in the glass. In summary, our results suggest a crystallization hierarchy on this glass matrix since the gamma-TeO2 and alpha-TeO2 phases crystallization occurs before the Li2Te2O5 phase crystallization. (c) 2006 Elsevier B.V. All rights reserved.. ...
Vol 70: Purification, crystallization and preliminary X-ray crystallographic studies of Rv3705c from Mycobacterium tuberculosis.. . Biblioteca virtual para leer y descargar libros, documentos, trabajos y tesis universitarias en PDF. Material universiario, documentación y tareas realizadas por universitarios en nuestra biblioteca. Para descargar gratis y para leer online.
The Czochralski (CZ) crystallization process is used to produce monocrystalline silicon. Monocrystalline silicon is used in solar cell wafers and in computers and electronics. The CZ process is a batch process, where multicrystalline silicon is melted in a crucible and later solidi es on a monocrystalline seed crystal. The crucible is heated using a heating element where the power is manipulated using a triode for alternating current (TRIAC). As the electric resistance of the heating element increases by increased temperature, there are signi cant dynamics from the TRIAC input signal (control system output) to the actual (measured) heating element power. The present paper focuses on empirical modeling of these dynamics. The modeling is based on a dataset logged from a real-life CZ process. Initially the dataset is preprocessed by detrending and handling outliers. Next, linear ARX, ARMAX, and output error (OE) models are identi ed. As the linear models do not fully explain the process behavior, ...
If you have a question about this talk, please contact Duncan Johnstone.. The lecture will highlight three experimental strategies that we have developed for exploring crystallization pathways and structural properties of solids: (i) in-situ solid-state NMR techniques for understanding the time-evolution of crystallization processes, (ii) the study of X-ray birefringence for spatially resolved mapping of the distribution of molecular orientations in materials, and (iii) structure determination of organic materials when single crystals cannot be prepared.. Our in-situ solid-state NMR technique [1-3] for studying crystallization pathways exploits the ability of NMR to selectively detect the solid phase in heterogeneous solid/liquid systems of the type that exist during crystallization from solution. We have shown that this technique can establish the sequence of solid phases formed during crystallization processes [1] and can be exploited in the discovery of new polymorphs [2]. Our most recent ...
TY - JOUR. T1 - Crystallization and preliminary X-ray analysis of an Escherichia coli purine repressor-hypoxanthine-DNA complex. AU - Schumacher, Maria A.. AU - Choi, Kang Yell. AU - Zalkin, Howard. AU - Brennan, Richard G.. PY - 1994/9/22. Y1 - 1994/9/22. N2 - The purine repressor (PurR) is a DNA-binding protein, which together with a purine corepressor serves to regulate de novo purine and pyrimidine biosynthesis in Escherichia coli. PurR belongs to the structurally homologous lac repressor family of transcription regulators. A PurR-hypoxanthine-DNA complex has been crystallized, with DNA encompassing the high affinity purF operator site and which is 16 base-pairs long with 5-deoxynucleoside overhangs on each complementary strand. The crystals diffract to better than 2.6 AÅ and take the orthorhombic space group C2221, with unit cell dimensions a = 175.9 AÅ, b = 94.8 AÅ and c = 81.8 AÅ. The structure determination of this PurR-hypoxanthine-DNA complex will provide the first high resolution ...
View Notes - GEOL101 - Slideshow 101.10 Magma from GEOL 101 at Central Washington University. Magma Magma Melting Crystallization Processes that impact composition Magma Creation of
Crystallization processes are used across the chemical, petrochemical and pharmaceutical industries. In the chemical industry, the potash and caustic...
An initial tranche of results from day-to-day use of a robotic system for setting up 100 nl-scale vapour-diffusion sitting-drop protein crystallizations has been surveyed. The database of over 50 unrelated samples represents a snapshot of projects currently at the stage of crystallization trials in Oxford research groups and as such encompasses a broad range of proteins. The results indicate that the nanolitre-scale methodology consistently identifies more crystallization conditions than traditional hand-pipetting-style methods; however, in a number of cases successful scale-up is then problematic. Crystals grown in the initial 100 nl-scale drops have in the majority of cases allowed useful characterization of X-ray diffraction, either in-house or at synchrotron beamlines. For a significant number of projects, full X-ray diffraction data sets have been collected to 3 Šresolution or better (either in-house or at the synchrotron) from crystals grown at the 100 nl scale. To date, five structures ...
The protozoan parasites of the Apicomplexa phylum are devastating global pathogens. Their success is largely due to phylum-specific proteins found in specialized organelles and cellular structures. The inner membrane complex (IMC) is a unique apicomplexan structure that is essential for motility, invasion and replication. The IMC subcompartment proteins (ISP) have recently been identified in Toxoplasma gondii and shown to be critical for replication, although their specific mechanisms are unknown. Structural characterization of TgISP1 was pursued in order to identify the fold adopted by the ISPs and to generate detailed insight into how this family of proteins functions during replication. An N-terminally truncated form of TgISP1 was purified from Escherichia coli, crystallized and subjected to X-ray diffraction analysis. Two crystal forms of TgISP1 belonging to space groups P4(1)32 or P4(3)32 and P2(1)2(1)2(1) diffracted to 2.05 and 2.1 Å resolution, respectively ...
TY - JOUR. T1 - Crystallization kinetics of sol-gel-derived (1-x)SrBi2Ta2O9-xBi3 TiTaO9 ferroelectric thin films. AU - Kwak, Woo Chul. AU - Sung, Yun Mo. PY - 2002/6. Y1 - 2002/6. N2 - The crystallization kinetics of Sr0.7Bi2.3Ta2O9 (SBT) and 0.7SrBi2Ta2O9-0.3Bi3 TiTaO9 (SBT-BTT) thin films formed by the sol-gel and spin coating techniques were studied. Phase formation and crystal growth are greatly affected by the film composition and crystallization temperature. Isothermal kinetic analysis was performed on the x-ray diffraction results of the thin films heated in the range of 730 to 760 °C at 10 °C intervals. Activation energy and Avrami exponent values were determined for the fluorite-to-Aurivillus phase transformation. A reduction of approximately 51 kJ/mol in activation energy was observed for the SBT-BTT thin films, and an Avrami exponent value of approximately 1.0 was obtained for both the SBT and SBT-BTT. A comparison is made, and the possible crystallization mechanism is ...
The work presented in this thesis represents the study of the polymorphism exhibited by several molecular, organic solid-state systems. In-situ techniques are used to explore aspects of the polymorphism and crystallization behaviour displayed by these systems. The crystal structures of new polymorphs and other solid phases are determined directly from powder X-ray diffraction data. Chapter 1 provides background information on the phenomenon of polymorphism and the importance of its study. In addition, the range of in-situ techniques that have been used to study crystallization and solid-state systems is described. Chapter 2 gives details on the experimental techniques used in the work presented in this thesis. These include powder X-ray diffraction (including the methodology behind structure determination from powder X-ray diffraction data), solid-state nuclear magnetic resonance (NMR) spectroscopy, X-ray photoelectron spectroscopy, thermal analysis techniques and dynamic vapour sorption. ...
A metal induced crystallization process is provided which employs an amorphous silicon film precursor deposited by physical vapor deposition, wherein the precursor film does not readily undergo crystallization by partial solid phase crystallization. Using this physical vapor deposition amorphous silicon precursor film, the amorphous silicon film is transformed to polysilicon by metal induced crystallization wherein the crystalline growth occurs fastest at regions that have been augmented with a metal catalyst and proceeds extremely slowly, practically zero, at regions which bear no metal catalyst. Accordingly, by use of the physical vapor deposition amorphous silicon precursor film in the process of the present invention, the metal induced crystallization process may take place at higher annealing temperatures and shorter annealing times without solid phase crystallization taking place. The process has a faster throughput than previous metal induced crystallization processes, results in a polysilicon
Crystallization from lipidic mesophase matrices is a promising route to diffraction-quality crystals and structures of membrane proteins. The microfluidic approach reported here eliminates two bottlenecks of the standard mesophase-based crystallization protocols: (i) manual preparation of viscous mesophases and (ii) manual harvesting of often small and fragile protein crystals. In the approach reported here, protein-loaded mesophases are formulated in an X-ray transparent microfluidic chip using only 60 nL of the protein solution per crystallization trial. The X-ray transparency of the chip enables diffraction data collection from multiple crystals residing in microfluidic wells, eliminating the normally required manual harvesting and mounting of individual crystals. In addition, we validated our approach by on-chip crystallization of photosynthetic reaction center, a membrane protein from Rhodobacter sphaeroides, followed by solving its structure to a resolution of 2.5 Å using X-ray ...
Glutathione synthetases catalyze the ATP-dependent synthesis of glutathione from L-γ-glutamyl-L-cysteine and glycine. Although these enzymes have been sequenced and characterized from a variety of biological sources, their exact catalytic mechanism is not fully understood and nothing is known about their adaptation at extremophilic environments. Glutathione synthetase from the Antarctic eubacterium Pseudoalteromonas haloplanktis (PhGshB) has been expressed, purified and successfully crystallized. An overall improvement of the crystal quality has been obtained by adapting the crystal growth conditions found with vapor diffusion experiments to the without-oil microbatch method. The best crystals of PhGshB diffract to 2.34 Å resolution and belong to space group P212121, with unit-cell parameters a = 83.28 Å, b = 119.88 Å, c = 159.82 Å. Refinement of the model, obtained using phases derived from the structure of the same enzyme from Escherichia coli by molecular replacement, is in progress. The
Direct tabletting technique has been widely used successfully for various drugs. But it strongly depends upon the quality of the crystals used. Crystals could be generated employing any of the available techniques like sublimation, solvent evaporation, vapor diffusion, thermal treatment and crystallization from melt precipitation by change in pH, growth in presence of additives or the grinding. Thus the novel agglomeration technique that transforms crystals themselves directly into a compacted spherical form during crystallization process has been desired. The use of spherical crystallization as a technique appears to be efficient alternative for obtaining suitable particles for direct compression. Spherical crystallization is a particle design technique, by which crystallization and agglomeration can be carried out simultaneously in one step and which has been successfully utilized for improvement of flowability and compactability of crystalline drugs.
Given by Dr Fabric Gorrec, LMB, Cambridge, UK. Advances in macromolecular X-ray crystallography depends upon solving structures from samples containing purified and concentrated protein, DNA, RNA, and their complexes. Novel samples are however increasingly challenging to produce and crystallize hence innovations which enhance the process of structure determination are urgently required, especially to increase the yield of quality diffraction crystals.. Experienced researchers from related fields, students and non-experts alike will find this webinar essential as it provides both theoretical and experimental evidence-based aspects of macromolecular X-ray crystallography. Delegates will leave with a better understanding about the underlying reasons why it is necessary to formulate novel crystallization screens with relatively complex conditions, such as the ones found in the MORPHEUS screens.. ...
PLA (Poly Lactic Acid) is a bio-sourced and biodegradable polymer. It represents an alternative for polymers issued from petrochemical synthesis. Unfortunately, the crystallization kinetics of PLA is very slow and limits the possibility to extend its application in several industrials domains. The enhancement of the PLA crystallization kinetic can be obtained by addition of nucleating agents of by ordering the molecular chains during flow, as in processing conditions. During processing of thermoplastic polymer experiences several thermomechanical conditions influencing drastically its final properties and mechanical behavior. During injection molding process, macromolecules are oriented and ordered due to the shear and elongation imposed by the melt flow in the mold during the filling step. As a consequence, supplementary nucleation is created in the polymer, leading to the acceleration of the crystallization kinetics. In this work, we propose to analyze and to quantify the role of the flow, the ...
The main objective of this work is to propose a mechanism for the transfer of impurities into the sucrose crystal. To this end the transfer of impurities into the sucrose crystal was investigated, under crystallisation conditions similar to those found industrially. Most of the impurities, namely, colour bodies, potassium, calcium and starch, were selected on the basis of their industrial importance, but some exotic species, namely lithium and nickel, were chosen to represent other mono- and di-valent ions respectively, and dyes, such as methylene blue, which have been used in work with single crystal sucrose crystallisation, were included to make the results more general. A parameter to measure the rate at which impurities are transferred into the sucrose crystal was proposed. Experiments, carried out in a pilot plant evaporative crystalliser, were performed to establish the effect of selected factors on both the concentrations of impurities found in the sucrose crystal, and on the rate at ...
The facility provides low volume crystallisation services and screen making. Our customers can also order custom built premixed crystallisation solutions. Full crystallisation service includes composition of the crystallisation setup and scheduled imaging of the experiment for up to four months. The crystallisation droplets are set up using our Mosquito LCP or Oryx nanodrop robots, which can use as little as 100 nl protein per experiment and are suitable for membrane proteins and for air-sensitive samples. Scientists can examine the maturation of the project over time and can pick up the crystallisation plate for an X-ray experiment. The facility is equipped with a dedicated imaging station for combined visible/UV epifluorescence imaging of very small protein crystals (2μm ...
Nonisothermal crystallization, melting behavior, and morphology of polypropylene (PP)/Easy processing polyethylene (EPPE) blends were studied by differential scanning alorimetry (DSC) and scanning electron microscope (SEM). The results showed that PP and EPPE are miscible, and there is no obvious phase separation in microphotographs of the blends. The modified Avrami analysis, Ozawa equation, and also Mo Z.S. method were used to analyze the nonisothermal crystallization kinetics of the blends. Values of Avrami exponent indicated the crystallization nucleation of the blends is homogeneous, the growth of spherulites is tridimensional, and crystallization mechanism of PP is not affected much by EPPE. The crystallization activation energy was estimated by Kissinger method. The result obtained from modified Avrami analysis, Mo Z.S. method, and Kissinger methods were well agreed. The addition of minor EPPE phase favored to decrease the overall crystallization rate of PP, showing some dilution effect ...
Puppo, C., Martini, S., Cerdeira, M., Hartel, R.W., and Herrera, M.L. 2002. Effect of Processing Conditions on Crystallization Kinetics and Rheology of Milk Fat/Sunflower Oil Blends Formulated with and without the Addition of Emulsifiers. 93rd AOCS Annual Meeting & Expo, Montreal, Quebec, Canada (oral presentation). ...
Malonyl-CoA:acyl-carrier protein transacylase (MCAT), encoded by the fabd gene, is a key enzyme in type II fatty-acid biosynthesis. It is responsible for transferring the malonyl group from malonyl-CoA to the holo acyl-carrier protein (ACP). Since the type II system differs from the type I system that mammals use, it has received enormous attention as a possible antibiotic target. In particular, only a single isoform of MCAT has been reported and a continuous coupled enzyme assay has been developed. MCAT from Staphylococcus aureus was overexpressed in Escherichia coli and the protein was purified and crystallized. Diffraction data were collected to 1.2 A ° resolution. The crystals belonged to space group P21, with unit-cell parameters a = 41.608, b = 86.717, c = 43.163 A ° , α = γ = 90, β = 106.330 °. The asymmetric unit contains one SaMCAT molecule ...
MyCrystals is designed as a user-friendly program to display crystal images and list crystallization conditions. The crystallization conditions entry fields can be customized to suit the experiments. MyCrystals is also able to sort the images by the entered crystallization conditions, which presents a unique opportunity to easily assess the effect of, for example, changing pH or concentration and thus establish the best conditions to be used for optimization ...
Our most popular line of protein crystallography screens - the Wizard Crystallization Screen Series. Shop now www.emeraldbiosystems.com.
2004. Cölfen, Helmut. The investigation of crystallization processes is a long established field of science. Crystals have a smallest unit called the unit cell and all crystal forms can be related to it with the consequence that crystals always exhibit planar surfaces. Crystals are built from ions or molecules. Recently, the investigation of so-called biominerals has revealed that not all crystals fit the classical textbook picture. For example biominerals, which are minerals deposited by living organisms like skeletons of algae, exhibit crystal morphologies with complex form, which even show untypical curvature. Thus they deviate significantly from the classical planar crystal surfaces. Furthermore, biominerals are often highly optimised composite materials like bones, teeth or mussle shells. This is achieved by a control of the crystallization process by structure directing molecules. Furthermore, recent investigations have revealed that these crystals are not always formed according to the ...
Methods are described wherein crystallization conditions determined in a microfluidic device are translated into crystallization conditions in alternati...
Disclosed is a method for the recovery of crystalline therephthalic acid containing less than 150 ppmw p-toluic acid by subjecting a solution of therephthalic acid containing minor amounts of p-toluic acid to crystallization in a crystallization zone comprising a plurality of series-connected crystallizers wherein the solution is subjected to rate-controlled evaporative cooling by sequential reduction in pressure and temperature to cause crystallization of therephthalic acid, wherein the pressure of the solution at the end of the crystallization zone is ambient pressure or less. Solvent which is evaporated from the crystallizers is collected and condensed and the condensed solvent is returned to the crystallization zone at a point subsequent to the crystallizer from which it was obtained.
Escherichia coli ribosomal RNA (rRNA) is post-transcriptionally modified by site-specific enzymes. The role of most modifications is not known and little is known about how these enzymes recognize their target substrates. In this thesis, we have structurally and functionally characterized two S-adenosyl-methionine (SAM) dependent 23S rRNA methyltransferases (MTases) that act during the early stages of ribosome assembly in E. coli.. RlmM methylates the 2O-ribose of C2498 in 23S rRNA. We have solved crystal structures of apo RlmM at 1.9Å resolution and of an RlmM-SAM complex at 2.6Å resolution. The RlmM structure revealed an N-terminal THUMP domain and a C-terminal catalytic Rossmann-fold MTase domain. A continuous patch of conserved positive charge on the RlmM surface is likely used for RNA substrate recognition. The SAM-binding site is open and shallow, suggesting that the RNA substrate may be required for tight cofactor binding. Further, we have shown RlmM MTase activity on in vitro ...
Model-based scale-up and optimisation is a powerful technique for achieving the desired product quality and reducing the cost of experimentation and the time to market. For complex crystallization processes, population balance modelling is capable of predicting the effect of the batch recipe on the particle size distribution (PSD) of the final product. However, this technique is mathematically complex and has traditionally required deep knowledge of specialist areas. New tools allow engineers to apply population balance modelling without highly-specialised numerical skills.. This webinar will present a case study illustrating the application of mechanistic model-based crystallization process analysis, scale-up and optimisation.. ...
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Two different crystal forms of human thioredoxin peroxidase-B have been grown by vapour diffusion using polyethylene glycol 400 as a precipitant. Monoclinic P21 crystals were grown from freshly purified protein, whilst orthorhombic P212121 crystals were grown from purified protein that had been stored in ammonium sulfate, but otherwise under the same conditions. The diffraction from both crystal forms was observed to extend to beyond 2.0 A resolution using synchrotron radiation. Complete native data sets to 1.8 and 3. 7 A have been collected from the monoclinic and orthorhombic crystals, respectively.
This year the course focused on micro and nano crystals and high throughput methods for synchrotrons and XFELs. Forty-three participants and 20 lecturers and tutors from the US and abroad discussed, and experienced hands-on, the complexity of the crystallization process. Nine lectures introducing basic concepts ranging from standard manual and automated crystallization methods to high density crystallization formats and injectors for XFELs preceded the practical and tutorial demonstration sessions. Nine different crystallization robotic systems were utilized and presented to the participants who could probe them during the tutorials to set their own crystallization trials. Twenty-three participants brought their own proteins and took advantage of the different methods being taught during the hands-on sessions. Crystals obtained were tested during the RapiData 2016 course that immediately followed this workshop. Several participants took home new crystallization conditions and even a few ...
Zn²⁺ is an essential nutrient for all known forms of life. In the major human pathogen Streptococcus pneumoniae, the acquisition of Zn²⁺ is facilitated by two Zn²⁺-specific solute-binding proteins: AdcA and AdcAII. To date, there has been a paucity of structural information on AdcA, which has hindered a deeper understanding of the mechanism underlying pneumococcal Zn²⁺ acquisition. Native AdcA consists of two domains: an N-terminal ZnuA domain and a C-terminal ZinT domain. In this study, the ZnuA domain of AdcA was crystallized. The initial crystals of the ZnuA-domain protein were obtained using dried seaweed as a heterogeneous nucleating agent. No crystals were obtained in the absence of the heterogeneous nucleating agent. These initial crystals were subsequently used as seeds to produce diffraction-quality crystals. The crystals diffracted to 2.03 Å resolution and had the symmetry of space group P1. This study demonstrates the utility of heterogeneous nucleation. The solution of ...
Seeded batch crystallizations of monohydrate citric acid were performed under isothermal conditions (15 degrees C). Continuous monitoring of the overall solid concentration during the crystallization process was developed using in situ Raman spectroscopy. Quantitative estimation of the crystal size distribution (CSD) was made possible thanks to in situ image acquisition: off-line CSD measurements were further computed from the recorded pictures. The growth rate of monohydrate citric acid was estimated from solid concentration. Through in situ particle size visualization and quantitative analysis of the pictures, activated surface secondary nucleation was also shown to significantly impact the final CSD. It is underlined that, in addition to continuous Raman in situ spectroscopic concentration measurements, image acquisition yields highly valuable data on the dispersed phase. Advantages and drawbacks of the technique for the monitoring of solution crystallization are discussed.