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1
Watts, David, Jochen Müller-Dieckmann, Gohar Tsakanova, Victor S. Lamzin e Matthew R. Groves. "Quantitive evaluation of macromolecular crystallization experiments using 1,8-ANS fluorescence". Acta Crystallographica Section D Biological Crystallography 66, n. 8 (10 luglio 2010): 901–8. http://dx.doi.org/10.1107/s0907444910020664.
Testo completoAbstract (sommario):
Modern X-ray structure analysis and advances in high-throughput robotics have allowed a significant increase in the number of conditions screened for a given sample volume. An efficient evaluation of the increased amount of crystallization trials in order to identify successful experiments is now urgently required. A novel approach is presented for the visualization of crystallization experiments using fluorescence from trace amounts of a nonspecific dye. The fluorescence images obtained strongly contrast protein crystals against other phenomena, such as precipitation and phase separation. Novel software has been developed to quantitatively evaluate the crystallization outcome based on a biophysical metric correlated with voxel protein concentration. In >1500 trials, 85.6% of the successful crystallization experiments were correctly identified, yielding a 50% reduction in the number of `missed hits' compared with current automated approaches. The use of the method in the crystallization of three previously uncharacterized proteins from the malarial parasitePlasmodium falciparumis further demonstrated.
2
Mele, Katarina, Rongxin Li, Vincent J. Fazio e Janet Newman. "Quantifying the quality of the experiments used to grow protein crystals: theiQCsuite". Journal of Applied Crystallography 47, n. 3 (29 maggio 2014): 1097–106. http://dx.doi.org/10.1107/s1600576714009728.
Testo completoAbstract (sommario):
Millions of crystallization trials are set up each year, with no clear metrics for determining if the experiments were correctly dispensed. This article reports the development of a software tool (iQC–image Quality Control) that recognizes factors associated with suboptimal experimental control during the setting up of protein crystallization trials. In its simplest form,iQCreturns a report that gives an overall rating to the quality of an experimental setup. TheiQCsoftware is able to identify many common problems observed in setting up crystallization trials – droplets that have associated splatter; droplets with air bubbles; the positional accuracy of droplet placement; elongated or otherwise `non-circular' drops – as well as detecting small and large droplets. An obvious use of this application is to track the status of the instrumentation used to set up crystallization trials in a multi-user laboratory.
3
Wilson, Julie, e Ian Berry. "The use of gradient direction in pre-processing images from crystallization experiments". Journal of Applied Crystallography 38, n. 3 (13 maggio 2005): 493–500. http://dx.doi.org/10.1107/s0021889805007442.
Testo completoAbstract (sommario):
Robots are now used routinely to perform crystallization experiments and many laboratories now have imaging systems to record the results. These images must be evaluated rapidly and the results fed back into optimization procedures. Software to analyse the images is being developed; described here are methods to restrict the area of the image to be analysed in order to speed up processing. Properties of the gradient of greyscale images are used to identify first the well and then the crystallization drop for various crystallization trays and different imaging systems. Methods are discussed to identify artefacts in the images that are not related to the experimental outcome, but can cause problems for the machine-learning algorithms used in classification and waste time during analysis. Gradient angles are exploited to eliminate faults in the crystallization trays, bubbles and splatter droplets prior to analysis.
4
Audic, Stéphane, Fabrice Lopez, Jean-Michel Claverie, Olivier Poirot e Chantal Abergel. "SAmBA: An interactive software for optimizing the design of biological macromolecules crystallization experiments". Proteins: Structure, Function, and Genetics 29, n. 2 (ottobre 1997): 252–57. http://dx.doi.org/10.1002/(sici)1097-0134(199710)29:2<252::aid-prot12>3.0.co;2-n.
Testo completo
5
Yamada, Yusuke, Naohiro Matsugaki, Masahiko Hiraki, Ryuichi Kato e Toshiya Senda. "In-situ diffraction experiments at the Photon Factory MX beamlines". Acta Crystallographica Section A Foundations and Advances 70, a1 (5 agosto 2014): C500. http://dx.doi.org/10.1107/s2053273314094996.
Testo completoAbstract (sommario):
Crystallization trial is one of the most important but time-consuming steps in macromolecular crystallography. Once a crystal appears in a certain crystallization condition, the crystal is typically harvested from the crystallization drop, soaked into a cryoprotection buffer, flash-cooled with a liquid nitrogen or cold gas flow and finally evaluated its diffraction quality by an X-ray beam. During these long process, crystal may be damaged and the result from the diffraction experiment does not necessarily reflect a nature of the crystal. On in-situ diffraction experiment, where a crystal in a crystallization drop is directly irradiated to an X-ray beam, a diffraction image from a crystal without any external factors such as harvesting and cryoprotection and, as a result, a nature of crystal can be evaluated quickly. In the Photon Factory, a new table-top diffractometer for in-situ diffraction experiments has been developed. It consists of XYZ translation stages with a plate handler, on-axis viewing system with a large numeric aperture and a plate rack where ten crystallization plates can be placed. These components sit on a common plate and it is placed on the existing diffractometer table in the beamline endstation. The CCD detector with a large active area and a pixel array detector with a small active area are used for acquiring diffraction images from crystals. Dedicated control software and user interface were also developed. Since 2014, user operation of the new diffractometer was started and in-situ diffraction experiments were mainly performed for evaluations of crystallization plates from a large crystallization screening project in our facility. BL-17A [1], one of micro-focus beamlines at the Photon Factory, is planned to be upgraded in March 2015. With this upgrade, a new diffractometer, which has a capability to handle a crystallization plate, will be installed so that diffraction data sets from crystals in crystallization drop can be collected.
6
Kang, Yue, Chao Liu, Yuzhu Zhang e Hongwei Xing. "Influence of Crystallization Behavior of Gas Quenching Blast Furnace Slag on the Preparation of Amorphous Slag Beads". Crystals 10, n. 1 (10 gennaio 2020): 30. http://dx.doi.org/10.3390/cryst10010030.
Testo completoAbstract (sommario):
Slag beads with different crystal content could be obtained through the gas quenching blast furnace slag (BFS) process. In order to increase the additional value of the slag beads as much as possible, it was necessary to restrain the crystallization of the slag beads as much as possible. In this paper, the mineral types and crystallization temperatures of BFS with different basicities and cooling rates were studied by using Factsage thermodynamic software, XRD, and differential scanning calorimeter (DSC) experiments, which obtained the gas quenching temperature and the cooling rate needed to restrain crystallization behavior in the gas quenching process; The crystallization mechanism was studied by calculating crystallization activation energy (Ec) using the DSC experiment, at the same time, the thermodynamic results were verified. The proper basicity and cooling rate of BFS were found to be conducive to the preparation of amorphous slag beads. The results showed that the initial crystallization temperature decreased with decreasing the basicity and increasing the cooling rate, which could increase the amorphous content of slag beads in the gas quenching process. The crystallization activation energy (Ec) increased with decreasing basicity, which increased the crystallization barrier.
7
Junius, Niels, Esko Oksanen, Maxime Terrien, Christophe Berzin, Jean-Luc Ferrer e Monika Budayova-Spano. "A crystallization apparatus for temperature-controlled flow-cell dialysis with real-time visualization". Journal of Applied Crystallography 49, n. 3 (22 aprile 2016): 806–13. http://dx.doi.org/10.1107/s1600576716004635.
Testo completoAbstract (sommario):
Many instrumentation developments in crystallization have concentrated on massive parallelization assays and reduction of sample volume per experiment to find initial crystallization conditions. Yet improving the size and diffraction quality of the crystals for diffraction studies often requires decoupling of crystal nucleation and growth. This in turn requires the control of variables such as precipitant and protein concentration, equilibration rate, and temperature, which are all difficult parameters to control in the existing setups. The success of the temperature-controlled batch method, originally developed to grow very large crystals for neutron crystallography, demonstrated that the rational optimization of crystal growth has potential in structural biology. A temperature-controlled dialysis button has been developed for our previous device, and a prototype of an integrated apparatus for the rational optimization of crystal growth by mapping and manipulating temperature–precipitant concentration phase diagrams has been constructed. The presented approach differs from the current paradigm, since it involves serial instead of parallel experiments, exploring multiple crystallization conditions with the same protein sample. The sample is not consumed in the experiment and the conditions can be changed in a reversible fashion, using dialysis with a flowing precipitant reservoir as well as precise temperature control. The control software allows visualization of the crystals, as well as control of the temperature and composition of the crystallization solution. The rational crystallization optimization strategies presented here allow tailoring of crystal size, morphology and diffraction quality, significantly reducing the time, effort and amount of expensive protein material required for structure determination.
8
Frølich, Simon, e Henrik Birkedal. "MultiRef: software platform for Rietveld refinement of multiple powder diffractograms fromin situ, scanning or diffraction tomography experiments". Journal of Applied Crystallography 48, n. 6 (19 novembre 2015): 2019–25. http://dx.doi.org/10.1107/s1600576715020099.
Testo completoAbstract (sommario):
Modern advanced diffraction experiments such asin situdiffraction, position-resolved diffraction or diffraction tomography generate extremely large data sets with hundreds to many thousands of diffractograms. Analyzing such data sets by Rietveld refinement is hampered by the logistics of running the Rietveld refinement program, extracting and analyzing the results, and possibly re-refining the data set based on an analysis of the preceding cycle of refinements. The complexity of the analysis may prevent some researchers either from performing the experiments or from conducting an exhaustive analysis of collected data. To this end, a MATLAB framework,MultiRef, which facilitates automated refinements, data extraction and intelligent choice of refinement model based on user choices, has been developed The use ofMultiRefis illustrated on data sets from diffraction tomography, position-resolved diffraction andin situpowder diffraction investigations of crystallization.
9
Murthy, Tal, Yongcheng Wang, Colin Reynolds e Titus J. Boggon. "Automated Protein Crystallization Trials Using the Thermo Scientific Matrix Hydra II eDrop". JALA: Journal of the Association for Laboratory Automation 12, n. 4 (agosto 2007): 213–18. http://dx.doi.org/10.1016/j.jala.2007.04.001.
Testo completoAbstract (sommario):
Obtaining suitable crystals for X-ray diffraction experiments is one of the rate-limiting steps in macromolecular crystallography. Robotic platforms that can increase throughput are highly desirable for crystal screening operations. The Thermo Scientific Matrix Hydra II eDrop is a liquid handling robot capable of dispensing sub-microliter and microliter volumes of solutions. Equipped with single-channel noncontact microdispenser, 96-channel syringe-based contact microdispenser and user-friendly ControlMate software, the Thermo Scientific Matrix Hydra II eDrop is appropriately designed for crystal screening experiments. The microdispensers are used in a single operational process to rapidly dispense sub-microliter volumes of liquids for automated crystallization plate setup. In this report, we discuss the design of the Thermo Scientific Matrix Hydra II eDrop. We also discuss an automated protocol for macromolecular crystallization trials that has successfully been used to produce crystals of a membrane protein, the rhomboid family intramembrane protease, GlpG. (JALA 2007;12:213–8)
10
Tian, Runze, Yu Zhang, Anhua Xu, Xuemei Li, Yunlong Hou e Bowen Tai. "Impact of Cooling on Water and Salt Migration of High-Chlorine Saline Soils". Geofluids 2021 (30 agosto 2021): 1–12. http://dx.doi.org/10.1155/2021/8612762.
Testo completoAbstract (sommario):
Secondary salinization is a common problem in saline soil projects. In order to grasp the mechanism of water and salt migration of high-chlorine saline soil during the cooling process, the saline soils along the Qarhan-Golmud Highway in the Qinghai-Tibet Plateau were selected as test samples. Firstly, the basic physical parameter test and the soluble salt chemical experiment were carried out and obtained liquid and plastic limits, dry density, etc. Secondly, freezing temperature experiments and water-salt migration experiments under one-way cooling conditions were conducted according to the actual environmental conditions, and after the temperature gradient line of the soil sample was stable, water content and labile salt chemistry experiments were conducted to obtain the distribution of water and salt contents of soil samples. Finally, the effect of crystallization-water phase transition on water and salt migration and the effect of chloride salt on the temperature of crystallization-water phase transition were considered, and a mathematical model applicable to the water and salt migration of highly chlorinated saline soils under the effect of unidirectional cooling was established and solved with COMSOL Multiphysics software, and the correctness of the model was verified by comparing the simulation results with the experimental results. The study found that (1) during the one-way cooling process, both water and salt showed a tendency to migrate to the cold end. The MC (saline soil with medium chlorine content) with an initial water content of 16.9% and Cl− content of 3.373% was measured to reach a 17.6% water content and 3.76% Cl− content at the cold (top) end after the experiment. The HC (saline soil with high chlorine content) with an initial water content of 6.6% and Cl− content of 17.928% was measured to reach a 6.83% water content and 18.8% Cl− content after the experiment and (2) after the one-way cooling experiment of the MC, the water content at a distance of 1–2 cm from the cold end has abrupt changes, which may be caused by a small amount of crystallization—water phase transition at this location. At the same time, according to the temperature change graph during the cooling process, the phase change temperature was set to −9°C in the numerical simulation process to match the experimental results.
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Daniel, Ed, Mirko M. Maksimainen, Neil Smith, Ville Ratas, Ekaterina Biterova, Sudarshan N. Murthy, M. Tanvir Rahman et al. "IceBear: an intuitive and versatile web application for research-data tracking from crystallization experiment to PDB deposition". Acta Crystallographica Section D Structural Biology 77, n. 2 (26 gennaio 2021): 151–63. http://dx.doi.org/10.1107/s2059798320015223.
Testo completoAbstract (sommario):
The web-based IceBear software is a versatile tool to monitor the results of crystallization experiments and is designed to facilitate supervisor and student communications. It also records and tracks all relevant information from crystallization setup to PDB deposition in protein crystallography projects. Fully automated data collection is now possible at several synchrotrons, which means that the number of samples tested at the synchrotron is currently increasing rapidly. Therefore, the protein crystallography research communities at the University of Oulu, Weizmann Institute of Science and Diamond Light Source have joined forces to automate the uploading of sample metadata to the synchrotron. In IceBear, each crystal selected for data collection is given a unique sample name and a crystal page is generated. Subsequently, the metadata required for data collection are uploaded directly to the ISPyB synchrotron database by a shipment module, and for each sample a link to the relevant ISPyB page is stored. IceBear allows notes to be made for each sample during cryocooling treatment and during data collection, as well as in later steps of the structure determination. Protocols are also available to aid the recycling of pins, pucks and dewars when the dewar returns from the synchrotron. The IceBear database is organized around projects, and project members can easily access the crystallization and diffraction metadata for each sample, as well as any additional information that has been provided via the notes. The crystal page for each sample connects the crystallization, diffraction and structural information by providing links to the IceBear drop-viewer page and to the ISPyB data-collection page, as well as to the structure deposited in the Protein Data Bank.
12
Grasza, Krzysztof, Emil Tymicki, Katarzyna Racka e Marek Orzyłowski. "Experimental Verification of a Novel System for the Growth of SiC Single Crystals". Materials Science Forum 679-680 (marzo 2011): 16–19. http://dx.doi.org/10.4028/www.scientific.net/msf.679-680.16.
Testo completoAbstract (sommario):
A set of single crystal growth experiments was performed in the new resistively heated two-heater furnace, which plays the role of an induction furnace with a moving coil. In this new experimental setup we are able to control the shape of the crystallization front, from flat to extremely convex. The positive results of the experimental tests differ significantly from prior discouraging interpretation of computational modeling results obtained by a commonly used software, previously presented in the literature. The essence of a new regulation of the temperature field during the crystal growth is a displacement of the maximum of the temperature field, which at the beginning of the growth is located close to the seed and it moves towards the source material as the crystal length increases. In this way, the crystallization front is heated with a similar intensity regardless the increasing crystal length.
13
Hall, David, Pierre Aller, Alun Ashton, Danny Axford, Alice Douangamath, Richard Fearn, Paul Hathaway, Karl Levik, Katherine McAuley e Mark Williams. "Remote Access to Diamond Light Source – Adding Flexibility to MX Experiments". Acta Crystallographica Section A Foundations and Advances 70, a1 (5 agosto 2014): C785. http://dx.doi.org/10.1107/s2053273314092146.
Testo completoAbstract (sommario):
Diamond Light Source (DLS) provides a suite of world-leading beamlines for macromolecular crystallography (MX) experiments which are used by scientists from all over the world. Key to their success is an integrated approach to automating the hardware and software environments such that it is only necessary to enter the beamline hutch to change large batches of samples for the robotic sample changers. Alongside investing in automation, all beamlines are also equipped with Pilatus 6M-F detectors (25 – 100 Hz) resulting in fast data collections and high turnover of samples. Rapid downstream processing of the resulting data has been developed since this is essential to drive experimental decisions. The feedback from these pipelines needs to be made readily available to users in a timely manner and a number of tools are available for both local and remote visualization of results. Remote access to these facilities was a design requirement from the outset. Several tools have been integrated and developed to streamline the process of remote access yet give the same software environment remotely as would be experienced if the experimenter was present at the beamline. The advent of remote access for cryogenically frozen samples has led to the implementation of new shift patterns for the user programme, enabling frequent short shifts for the many groups who use DLS. Remote access to MX beamlines is also a prerequisite of many industrial clients of DLS. For the future we are moving forward with the development of remote access for in-situ data collection from crystallization plates following on from the success of this method for screening and collecting data by users at the beamlines. The implementation and impact of remote access at DLS will be presented here.
14
Biglione, Jordan, Yves Bereaux, J. Y. Charmeau, Renaud G. Rinaldi, Jean Balcaen e Sambor Chhay. "Injection Blow Moulding Single Stage Process – Approach of the Material Behaviour in Process Conditions and Numerical Simulation". Key Engineering Materials 651-653 (luglio 2015): 805–11. http://dx.doi.org/10.4028/www.scientific.net/kem.651-653.805.
Testo completoAbstract (sommario):
Single stage injection blow moulding process, without preform storage and reheat, could be run on a standard injection moulding machine, with the aim of producing short series of specific hollow parts. In this process, the preform is being blow moulded after a short cooling time. Polypropylene (Random copolymer) is a suitable material for this type of process. The preform has to remain sufficiently melted to be blown. This single stage process introduces temperature gradients, molecular orientation, high stretch rates and high cooling rates. These constraints lead to a small processing window, and in practice, the process takes place between the melting temperature and the crystallization temperature. To investigates the mechanical behaviour in conditions as close to the process as possible, we ran a series of experiments: First, Dynamical Mechanical Analysis was performed starting from the solid state at room temperature and ending in the vicinity of the melting temperature. Conversely, oscillatory rheometry was also performed starting this time from the molten state at 200°C and decreasing the temperature down to the vicinity of the crystallization temperature. The influence of the shear rate and of the cooling kinetics on the enhancement of the mechanical properties when starting from the melt is discussed. This enhancement is attributed to the crystallization of the material. The question of the crystallization occurring at such high stretch rates and high cooling rates is open. A viscous Cross model has been proved to be relevant to the problem. Thermal dependence is assumed by an Arrhenius law. The process is simulated through a finite element code (POLYFLOW software) in the Ansys Workbench framework. Thickness measurements using image analysis are performed and comparison with the simulation results is satisfactory.
15
Xu, Hongliang. "Structure determination from X-ray powder diffraction data at low resolution". Acta Crystallographica Section A Foundations and Advances 70, a1 (5 agosto 2014): C143. http://dx.doi.org/10.1107/s2053273314098568.
Testo completoAbstract (sommario):
Knowledge of the structural arrangement of atoms in solids is necessary to facilitate the study of their properties. The best and most detailed structural information is obtained when the diffraction pattern of a single crystal a few tenths of a millimeter in each dimension is analyzed, but growing high-quality crystals of this size is often difficult, sometimes impossible. However, many crystallization experiments that do not yield single crystals do yield showers of randomly oriented micro-crystals that can be exposed to X-rays simultaneously to produce a powder diffraction pattern. Direct Methods routinely solve crystal structures when single-crystal diffraction data are available at atomic resolution (1.0-1.2Å), but fail to determine micro-crystal structures due to reflections overlapping and low-resolution powder diffraction data. By artificially and intelligently extending the measured data to atomic resolution, we have successfully solved structures having low-resolution diffraction data that were hard to solve by other direct-method based computation procedures. The newly developed method, Powder Shake-and-Bake, is implemented in a computer program PowSnB. PowSnB can be incorporated into the state-of-the-art software package EXPO that includes powder data reduction, structure determination and structure refinement. The new combination could have potential to solve structures that have never been solved before by direct-methods approach.
16
Colin, Béatrice, Benoit Deprez e Cyril Couturier. "High-Throughput DNA Plasmid Transfection Using Acoustic Droplet Ejection Technology". SLAS DISCOVERY: Advancing the Science of Drug Discovery 24, n. 4 (5 ottobre 2018): 492–500. http://dx.doi.org/10.1177/2472555218803064.
Testo completoAbstract (sommario):
The Labcyte Echo acoustic liquid handler allows accurate droplet ejection at high speed from a source well plate to a destination plate. It has already been used in various miniaturized biological assays, such as quantitative PCR (q-PCR), quantitative real-time PCR (q-RT-PCR), protein crystallization, drug screening, cell dispensing, and siRNA transfection. However, no plasmid DNA transfection assay has been published so far using this dispensing technology. In this study, we evaluated the ability of the Echo 550 device to perform plasmid DNA transfection in 384-well plates. Due to the high throughput of this device, we simultaneously optimized the three main parameters of a transfection process: dilution of the transfection reagent, DNA amount, and starting DNA concentration. We defined a four-step protocol whose optimal settings allowed us to transfect HeLa cells with up to 90% efficiency and reach a co-expression of nearly 100% within transfected cells in co-transfection experiments. This fast, reliable, and automated protocol opens new ways to easily and rapidly identify optimal transfection settings for a given cell type. Furthermore, it permits easy software-based transfection control and multiplexing of plasmids distributed on wells of a source plate. This new development could lead to new array applications, such as human ORFeome protein expression or CRISPR-Cas9-based gene function validation in nonpooled screening strategies.
17
Adams, J. A., D. Jewell, K. Jorgensen, M. Mickley e J. M. Newman. "Image Capture and Analysis for Macromolecular Crystal Growth Using RoboMicroscope™II". JALA: Journal of the Association for Laboratory Automation 7, n. 6 (dicembre 2002): 36–40. http://dx.doi.org/10.1016/s1535-5535-04-00224-2.
Testo completoAbstract (sommario):
The RoboMicroScope II is an image capture and analysis system, which enables the automated analysis of protein crystallization trials. The RoboMicroscope II couples robust hardware with intuitive software that tracks and assigns an objective score to each instance of a crystallization experiment. This machine can also be used in a manual mode, to increase the reliability, objectivity and efficiency of human scoring of crystallization trials.
18
Chen, Biao, Tie Lin Shi, Guang Lan Liao e Zhi Jing Zhu. "Friction Welding of Zr41Ti14Cu12.5Ni10Be22.5 Bulk Metallic Glass and Temperature Field Simulation". Advanced Materials Research 528 (giugno 2012): 144–51. http://dx.doi.org/10.4028/www.scientific.net/amr.528.144.
Testo completoAbstract (sommario):
In order to enhance the application of bulk metallic glass (BMG) as engineer material, it is necessary to develop appropriate bonding technology to solve the problems of size limitation and weldability. In this work, a friction welding set-up was constructed, and the Zr41Ti14Cu12.5Ni10Be22.5 BMG rods were joined. The joint interface zone was examined by X-ray diffraction, Scanning electron microscope, Vickers Micro-hardness and Transmission electron microscope. The results showed that the BMG rods were successfully joined, where no crystallization and visible defects were observed. The welding joint maintained the amorphous structure except few nanocrystallines occurred. Then the temperature field simulation was executed using ANSYS finite element software to optimize the welding parameters. It indicated that friction time cannot exceed 0.25s under the given experiment conditions, otherwise the crystallization would occurred, which is in good agreement with the experiment. It is concluded that the temperature field simulation can be used to guide the experiment and the friction welding can be used to join the BMG.
19
Tratsiak, Katsiaryna, Tatyana Prudnikova, Ivana Drienovska, Lukas Chrast, Jiri Damborsky, Pavlina Rezacova, Michal Kuty, Radka Chaloupkova e Ivana Kuta Smatanova. "Crystal structure of the novel haloalkane dehalogenases". Acta Crystallographica Section A Foundations and Advances 70, a1 (5 agosto 2014): C1678. http://dx.doi.org/10.1107/s2053273314083211.
Testo completoAbstract (sommario):
Haloalkane dehalogenases (EC 3.8.1.5; HLDs) are microbial enzymes with catalytic activity for the hydrolytic conversion of xenobiotic and highly toxic halogenated aliphatic compounds to the corresponding alcohols. Biodegradation, biosensing, biocatalysis and cellular imaging are potentially practical applications for the HLDs. Two newly isolated and purified psychrophilic haloalkane dehalogenases, exhibiting interesting catalytic properties, DpcA from Psychrobacter cryohalolentis K5 and DmxA from Marinobacter sp. ELB17, were used for the crystallization experiments and structure determination. Diffracted crystals of DpcA(left) and DmxA(right) (see figure, the scale bar -100μm) were refined up to the 1.05 Å and 1.45 Å resolutions, respectively. Diffraction data for DpcA were collected on beamline 14.2 at the BESSY II electron-storage ring (Helmholtz-Zentrum Berlin (HZB), Germany) and equipped with a Rayonics MX-225 CCD detector at the wavelengths of 0.978 Å, and for DmxA were collected using Pilatus 6M-F detector at the wavelengths of 0.972 Å on the beamline ID29, at the European Synchrotron Radiation Facility (ESRF) in Grenoble (France). Crystals of DpcA belonged to P21 space group with unit-cell parameters: a = 41.3, b = 79.4, c = 43.5 A °, α = β = 90.0, γ = 95.0 and contained 1 molecule in the asymmetric unit. Crystals of DmxA belonged to P212121 space group, with unit-cell parameters: a = 43.371, b = 78.343, c = 150.51; α = γ = β = 90.0 and contained 2 molecules in the asymmetric unit. The structures were solved by molecular replacement with MOLREP from the CCP4 software suite. The coordinates of Xanthobacter autotrophicus (PDB code: 1B6G; 40% sequence identities for 121 residues and 53% sequence similarity was used as search model for DpcA structure and for DmxA from Rhodococcus rhodochrous (PDB entry 4E46; 48% sequence identity for 142 residues and 63% sequence similarity). Belonging to the superfamily of α/β - hydrolases, according to the catalytic pentad, HLDs are subdivided onto the three subfamilies. DpcA belongs to the HLD - I: Asp- His - Asp + Trp - Trp and DmxA to the HLD – II: Asp - His - Glu + Asn - Trp. We thank M. Weiss and S. Pühringer (BESSY). This work is supported by the Grant Agency of the Czech Republic (P207/12/0775).Also by the Ministry of Education of the Czech Republic (CZ.1.05/2.1.00/01.0024 and CZ.1.05/2.1.00/01.0001). The support of the Academy of Sciences of the Czech Republic is acknowledged as well.
20
Fasevich, Yu N., e F. I. Rudnitsky. "Structure for interaction software process modules in the development of technological processes of cast". Litiyo i Metallurgiya (FOUNDRY PRODUCTION AND METALLURGY), n. 1 (10 aprile 2019): 28–33. http://dx.doi.org/10.21122/1683-6065-2019-1-28-33.
Testo completoAbstract (sommario):
On the basis of the General criterion of quality the problem-oriented program technological algorithm for adjustment of technological parameters at the expense of reception of the characteristics investigated thermophysical properties of the profits providing the steady mode of imposing of hydrodynamic pressure before the beginning of crystallization of casting as a result of heating of profitable part of the interconnected elements «Gating system–casting» is developed. The software algorithm uses the means of computational experiment to determine the optimal values of the parameters in the development of cast processes. Optimization of the thermal regime is reduced to the analysis of the results of the studied thermophysical properties of top ingot due to the heating of the profitable part of the Gating-feeding system. The tested parameters are: temperature in top ingot in crystallized metal; wall thickness of top ingot; thermophysical reaction; the speed of the die casting liquid steel; the height of the heel of metal in top ingot.
21
Bartocha, D., T. Wróbel, J. Szajnar, W. Adamczyk, W. Jamrozik e M. Dojka. "The Influence of Casting Velocity on Structure of Al Continuous Ingots". Archives of Metallurgy and Materials 62, n. 3 (26 settembre 2017): 1609–13. http://dx.doi.org/10.1515/amm-2017-0246.
Testo completoAbstract (sommario):
AbstractThe aim of paper was determination of influence of the casting velocity in horizontal continuous casting process on solidification phenomenon and next primary structure of aluminum ingots. In the range of studies was conducted the experiment concerning continuous casting of Al ingots with diameter 30 mm at velocity from 30 to 80 mm/min. Moreover was developed adequate to the real the virtual model of cooled water continuous casting mould, which was used in simulation of solidification process of Al continuous ingot, made in ANSYS Fluent software. In result was determined the influence of casting velocity and temperature of cooling water on position of crystallization front inside the continuous casting mould. While the shape and size of grains in primary structure of Al continuous ingots were determined on the basis of metallographic macroscopic studies. On the basis of the results analysis was affirmed that increase of casting velocity strongly influences on position of crystallization front and causes increase of temperature of ingot leaving the continuous casting mould. In result the increase of casting velocity supposedly leads to decrease of temperature gradient on crystallization front what creates coarse grains in primary structure of aluminum continuous ingots and caused low usable properties i.e. suitability to plastic deformation.
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Nawrocki, Jacek, Dariusz Szeliga, Krzysztof Kubiak, Hubert Matysiak, Maciej Motyka e Waldemar Ziaja. "Influence of Process Parameters on Cooling Conditions in Nickel Base Superalloy Investment Casting". Key Engineering Materials 641 (aprile 2015): 124–31. http://dx.doi.org/10.4028/www.scientific.net/kem.641.124.
Testo completoAbstract (sommario):
The published results of the research on crystallization process of nickel base superalloy castings rarely take into account the effect of the wall thickness of the casting. Current study presents a comprehensive assessment of the impact of molten alloy temperature, mould temperature, mould thermal insulation and casting diameter on crystallization process of polycrystalline nickel base superalloy. Research was designed and conducted as an factorial experiment at two levels. Different diameter samples were designed and optimised by the numerical simulation of solidification process using ProCAST software. Inconel 713C nickel based superalloy was cast into alumina-silicate moulds produced by lost wax technique. Casting temperature during solidification was measured using thermocouples installed in sections having a diameter of 10 and 20 mm. Statistical analysis of the influence of the main process parameters and casting diameter on cooling rate, total freezing temperature range and critical temperature range was performed. Cooling rates in the range from 0.21 to 1.24°C/s were obtained. It was found that diameter of the casting, mould temperature and the thermal insulation of the mould had significant effect on the cooling rate.
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Jin, Hai Peng, e Jia Rong Li. "Grain Competitive Growth Prediction during Solidification in Single Crystal Superalloy DD6 Castings". Materials Science Forum 783-786 (maggio 2014): 2148–53. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.2148.
Testo completoAbstract (sommario):
Competitive growth and grain selection were simulated and analyzed during the directional solidification with the conditions for single crystal superalloy DD6 castings using Commercial software, ProCAST. A three dimensional cellular automaton (CA) model coupled with finite-element (FE) heat flow calculation was applied. Measurements at the grain scale were made using the EBSD method at the cross sections in the starter block and grain selector at an interval of 4 mm from the chill surface. The grain characteristics and the rules of competition growth were obtained. The validity of the simulation results were compared with those of the experiment. It concluded that the model-predicted tendency shows satisfactory agreement with the experiment. Increasing the distance from the chill decreases the number of grains, increases the radius of grains and drives the crystallization orientation of grains to principal stress orientation.
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Yan, Yuhong, Yong Liang, Abhijeet Roy e Xinge Du. "Web Service Enabled Online Laboratory". International Journal of Web Services Research 6, n. 4 (ottobre 2009): 75–93. http://dx.doi.org/10.4018/jwsr.2009071304.
Testo completoAbstract (sommario):
Online experimentation allows students from anywhere to operate remote instruments at any time. The current techniques constrain users to bind to products from one company and install client side software. We use Web services and Service Oriented Architecture to improve the interoperability and usability of the remote instruments. Under a service oriented architecture for online experiment system, a generic methodology to wrap commercial instruments using IVI and VISA standard as Web services is developed. We enhance the instrument Web services into stateful services so that they can manage user booking and persist experiment results. We also benchmark the performance of this system when SOAP is used as the wire format for communication and propose solutions to optimize performance. In order to avoid any installation at the client side, the authors develop Web 2.0 based techniques to display the virtual instrument panel and real time signals with just a standard Web browser. The technique developed in this article can be widely used for different real laboratories, such as microelectronics, chemical engineering, polymer crystallization, structural engineering, and signal processing.
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Hantke, Max F., Tomas Ekeberg e Filipe R. N. C. Maia. "Condor: a simulation tool for flash X-ray imaging". Journal of Applied Crystallography 49, n. 4 (14 luglio 2016): 1356–62. http://dx.doi.org/10.1107/s1600576716009213.
Testo completoAbstract (sommario):
Flash X-ray imaging has the potential to determine structures down to molecular resolution without the need for crystallization. The ability to accurately predict the diffraction signal and to identify the optimal experimental configuration within the limits of the instrument is important for successful data collection. This article introducesCondor, an open-source simulation tool to predict X-ray far-field scattering amplitudes of isolated particles for customized experimental designs and samples, which the user defines by an atomic or a refractive index model. The software enables researchers to test whether their envisaged imaging experiment is feasible, and to optimize critical parameters for reaching the best possible result. It also aims to support researchers who intend to create or advance reconstruction algorithms by simulating realistic test data.Condoris designed to be easy to use and can be either installed as a Python package or used from its web interface (http://lmb.icm.uu.se/condor). X-ray free-electron lasers have high running costs and beam time at these facilities is precious. Data quality can be substantially improved by using simulations to guide the experimental design and simplify data analysis.
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Yu, Jia, Xuan Chen, Xiaoliang Ma, Qingfei Song, Yukun Zhao e Jiahao Cao. "Influence of Nanoparticles and Graphite Foam on the Supercooling of Acetamide". Journal of Nanomaterials 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/313674.
Testo completoAbstract (sommario):
Acetamide is a promising phase change materials (PCMs) for thermal storage,but the large supercooling during the freezing process has limited its application. In this study, we prepared acetamide-SiO2composites by adding nano-SiO2into acetamide. This modified PCM was then impregnated into the porous graphite foam forming acetamide-SiO2-graphite foam form-stable composites. These composites were subjected to melting-solidification cycles 50 times; the time-temperature curves were tracked and recorded during these cycles. The time-temperature curves showed that, for the acetamide containing 2 wt. % SiO2, the supercooling phenomenon was eliminated and the material’s performance was stable for 50 cycles. The solidification temperature of the acetamide-SiO2-graphite foam samples was 65°C and the melting temperature was lowered to 65°C. The samples exhibited almost no supercooling and the presence of SiO2had no significant effect on the melting-solidification temperature. The microscopic supercooling of the acetamide-SiO2composite was measured using differential scanning calorimetry (DSC). The results indicated that when the content of SiO2was 1 wt. to 2 wt. %, the supercooling could be reduced to less than 10°C and heat was sufficiently released during solidification. Finally, a set of algorithms was derived using MATLAB software for simulating the crystallization of samples based on the classical nucleation theory. The results of the simulation agreed with the experiment results.
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Zhao, Q. L., e J. Ding. "Nutrient removal and recovery from nitrogen- and phosphorus-laden waste streams in the form of struvite". Water Practice and Technology 6, n. 4 (1 dicembre 2011). http://dx.doi.org/10.2166/wpt.2011.0072.
Testo completoAbstract (sommario):
For the purpose of waste conversion into resources, removal and recovery of nutrients from different scenarios of nitrogen- and phosphorus-laden waste streams in the form of struvite (MgNH4PO4 6H2O, MAP) were presented in this paper. Nutrients-laden waste streams included urine, landfill leachate, industrial wastewater and the side streams in wastewater treatment plants etc. Batch experiments and software model were applied to obtain the optimal operational conditions. Several kinds of struvite reactors were introduced and compared. Under the optimal conditions, the recovery efficiency of NH4+-N and PO43–-P from urine separation could reach above 95% and 85%, respectively, while highly efficient recovery of nutrients was also realized for other kinds of wastewater. Some engineering examples on struvite crystallization were also discussed, indicating a feasible process for engineering application. Furthermore, the struvite recovered could not only be reused as a fertilizer, but also significantly reduce the organic load of wastewater treatment plants and improve effluent quality.
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Lwanyaga, Joseph Ddumba, Hillary Kasedde e John Baptist Kirabira. "Effect of Temperature on Mineral Precipitation Sequence of Lake Katwe Brine during Evaporation". Current Journal of Applied Science and Technology, 19 marzo 2019, 1–12. http://dx.doi.org/10.9734/cjast/2019/v33i630104.
Testo completoAbstract (sommario):
The effect of temperature on the mineral precipitation sequence during evaporation of the natural brine from lake Katwe was studied. Laboratory isothermal evaporation experiments at temperatures (30, 40, 50, 60 and 70 ) using the original Katwe surface brine were undertaken. PHREEQC, a solubility software was used to predict the crystallization paths at the different study temperatures. The mineralogy and morphology of the precipitates were determined by the XRD and SEM techniques, respectively. The precipitation sequence majorly started with sulphates followed by chlorides and lastly carbonates at all temperatures after precipitation of the calcium-magnesium carbonates. Halite emerged the most dominant mineral, with thernadite, trona and glaserite following respectively. Thenardite, glaserite and burkeite precipitation flourished at lower temperatures (30 and 40 ) whereas soda ash precipitation flourished at higher temperatures (60 and 70 . Halite equally precipitated at all temperatures thus not showing a temperature preference in this study. Temperature variation is a key design parameter in the extraction of mineral salts from the Brines of Lake Katwe.
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Chumanov, I. V., A. N. Anikeev e D. A. Zherebtsov. "Influence of dispersed particles of tungsten carbide on the microstructure of 12Kh18N10T steel obtained by centrifugal casting". Chernye Metally, 28 dicembre 2020, 68–73. http://dx.doi.org/10.17580/chm.2020.12.10.
Testo completoAbstract (sommario):
The development of new technologies in various industries, such as fast neuron reactors, require a new level of operational properties from steels and raise the issues of resistance to neutron radiation, radiation swelling, embrittlement and creep, and the level of residual activation. The principal way to increase these properties is to adjust the chemical composition, and rearrange the crystal structure of the metal. The authors propose to achieve this by introducing finely dispersed particles into the melt and controlled by them to “reinforce” the crystal lattice, grinding the metal structure. During the work, using the FactSage software package, thermodynamic modeling of the interaction of dispersed particles with a 18Х18Н10T steel melt was carried out, showing that the particles will interact with the metal melt, which can lead to their complete dissociation, and at the next stage of crystallization, regardless of the degree of dissolution of tungsten carbide, the formation of carbide phases based on titanium carbide with an FSS structure, as well as a carbide phase based on chromium carbide with the formula M23C3, will become. According to the simulation parameters, experiments were conducted, experimental blanks with different contents of the introduced tungsten carbide were obtained, and heat treatment was carried out. The study of microstructures showed that the introduced particles of tungsten carbide completely dissociate when interacting with a metal melt and contribute to an increase in ferrite in the microstructure of the workpiece. Studies of microhardness confi rmed the significant effect of the introduced carbide on the properties of the material: the maximum values of microhardness are achieved at a high concentration of refractory particles in the areas of their maximum concentration (outer edge of the workpieces). Carrying out heat treatment reduces microhardness, while aligning the gradient of properties with the volume of castings. This work was financially supported by the Ministry of Science and Higher Education of the Russian Federation within the framework of the federal target program under Agreement No. 075-15-2019-1711 (internal number 05.608.21.0276) dated December 04, 2019 (unique project identifier RFMEFI60819X0276).