WorldWideScience

Sample records for macromolecule crystal quality

  1. An Overview of Biological Macromolecule Crystallization

    Directory of Open Access Journals (Sweden)

    Irene Russo Krauss

    2013-05-01

    Full Text Available The elucidation of the three dimensional structure of biological macromolecules has provided an important contribution to our current understanding of many basic mechanisms involved in life processes. This enormous impact largely results from the ability of X-ray crystallography to provide accurate structural details at atomic resolution that are a prerequisite for a deeper insight on the way in which bio-macromolecules interact with each other to build up supramolecular nano-machines capable of performing specialized biological functions. With the advent of high-energy synchrotron sources and the development of sophisticated software to solve X-ray and neutron crystal structures of large molecules, the crystallization step has become even more the bottleneck of a successful structure determination. This review introduces the general aspects of protein crystallization, summarizes conventional and innovative crystallization methods and focuses on the new strategies utilized to improve the success rate of experiments and increase crystal diffraction quality.

  2. Unsolved problems of crystallization and melting of flexible macromolecules

    International Nuclear Information System (INIS)

    Wunderlich, B.

    1992-01-01

    The thermodynamics, kinetics, and computer simulations of crystallization and melting is discussed. The thermodynamics is shown to be well understood, although for many specific crystals not enough details for full description are available. Experiments on the crystallization kinetics of poly(ethylene) and poly(oxyethylene) in the presence of crystal nuclei as a function of molecular mass revealed that with increasing mass, the crystallization behavior deviates increasingly from that of small, rigid molecules. Instead of showing a continuously changing, linear crystallization rate with temperature through the equilibrium melting temperature, T m 0 , these flexible macromolecules show a region of practically zero crystallization rate between T m 0 and about (T m 0 - 15) K, creating a temperature region of metastability in the melt that cannot be broken by nucleation with pregrown crystals. Molecular Nucleation was proposed as a cooperative process to be of overriding importance for the description of polymer crystallization, and to be at the center of segregation of molecules of lower molecular mass by growing crystal fronts. Initial efforts to model sufficiently large crystals using Monte Carlo and molecular dynamics methods are presented. Some of the short-time intermediates in the melting, crystallization, and annealing processes seem to have little similarity to commonly assumed models of crystallization and melting and are presented as discussion topics

  3. Maximizing Macromolecule Crystal Size for Neutron Diffraction Experiments

    Science.gov (United States)

    Judge, R. A.; Kephart, R.; Leardi, R.; Myles, D. A.; Snell, E. H.; vanderWoerd, M.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    A challenge in neutron diffraction experiments is growing large (greater than 1 cu mm) macromolecule crystals. In taking up this challenge we have used statistical experiment design techniques to quickly identify crystallization conditions under which the largest crystals grow. These techniques provide the maximum information for minimal experimental effort, allowing optimal screening of crystallization variables in a simple experimental matrix, using the minimum amount of sample. Analysis of the results quickly tells the investigator what conditions are the most important for the crystallization. These can then be used to maximize the crystallization results in terms of reducing crystal numbers and providing large crystals of suitable habit. We have used these techniques to grow large crystals of Glucose isomerase. Glucose isomerase is an industrial enzyme used extensively in the food industry for the conversion of glucose to fructose. The aim of this study is the elucidation of the enzymatic mechanism at the molecular level. The accurate determination of hydrogen positions, which is critical for this, is a requirement that neutron diffraction is uniquely suited for. Preliminary neutron diffraction experiments with these crystals conducted at the Institute Laue-Langevin (Grenoble, France) reveal diffraction to beyond 2.5 angstrom. Macromolecular crystal growth is a process involving many parameters, and statistical experimental design is naturally suited to this field. These techniques are sample independent and provide an experimental strategy to maximize crystal volume and habit for neutron diffraction studies.

  4. Carboxylic acids in crystallization of macromolecules: learning from successful crystallization experiments.

    Science.gov (United States)

    Offermann, Lesa R; He, John Z; Mank, Nicholas J; Booth, William T; Chruszcz, Maksymilian

    2014-03-01

    The production of macromolecular crystals suitable for structural analysis is one of the most important and limiting steps in the structure determination process. Often, preliminary crystallization trials are performed using hundreds of empirically selected conditions. Carboxylic acids and/or their salts are one of the most popular components of these empirically derived crystallization conditions. Our findings indicate that almost 40 % of entries deposited to the Protein Data Bank (PDB) reporting crystallization conditions contain at least one carboxylic acid. In order to analyze the role of carboxylic acids in macromolecular crystallization, a large-scale analysis of the successful crystallization experiments reported to the PDB was performed. The PDB is currently the largest source of crystallization data, however it is not easily searchable. These complications are due to a combination of a free text format, which is used to capture information on the crystallization experiments, and the inconsistent naming of chemicals used in crystallization experiments. Despite these difficulties, our approach allows for the extraction of over 47,000 crystallization conditions from the PDB. Initially, the selected conditions were investigated to determine which carboxylic acids or their salts are most often present in crystallization solutions. From this group, selected sets of crystallization conditions were analyzed in detail, assessing parameters such as concentration, pH, and precipitant used. Our findings will lead to the design of new crystallization screens focused around carboxylic acids.

  5. A 7 µm mini-beam improves diffraction data from small or imperfect crystals of macromolecules

    International Nuclear Information System (INIS)

    Sanishvili, Ruslan; Nagarajan, Venugopalan; Yoder, Derek; Becker, Michael; Xu, Shenglan; Corcoran, Stephen; Akey, David L.; Smith, Janet L.; Fischetti, Robert F.

    2008-01-01

    An X-ray mini-beam of 8 × 6 µm cross-section was used to collect diffraction data from protein microcrystals with volumes as small as 150–300 µm 3 . The benefits of the mini-beam for experiments with small crystals and with large inhomogeneous crystals are investigated. A simple apparatus for achieving beam sizes in the range 5-10 µm on a synchrotron beamline was implemented in combination with a small 125 × 25 µm focus. The resulting beam had sufficient flux for crystallographic data collection from samples smaller than 10 × 10 × 10 µm. Sample data were collected representing three different scenarios: (i) a complete 2.0 Å data set from a single strongly diffracting microcrystal, (ii) a complete and redundant 1.94 Å data set obtained by merging data from six microcrystals and (iii) a complete 2.24 Å data set from a needle-shaped crystal with less than 12 × 10 µm cross-section and average diffracting power. The resulting data were of high quality, leading to well refined structures with good electron-density maps. The signal-to-noise ratios for data collected from small crystals with the mini-beam were significantly higher than for equivalent data collected from the same crystal with a 125 × 25 µm beam. Relative to this large beam, use of the mini-beam also resulted in lower refined crystal mosaicities. The mini-beam proved to be advantageous for inhomogeneous large crystals, where better ordered regions could be selected by the smaller beam

  6. Simultaneous X-ray diffraction from multiple single crystals of macromolecules

    DEFF Research Database (Denmark)

    Paithankar, Karthik S.; Sørensen, Henning Osholm; Wright, Jonathan P.

    2011-01-01

    The potential in macromolecular crystallography for using multiple crystals to collect X-ray diffraction data simultaneously from assemblies of up to seven crystals is explored. The basic features of the algorithms used to extract data and their practical implementation are described. The procedure...

  7. Fully automatic characterization and data collection from crystals of biological macromolecules

    International Nuclear Information System (INIS)

    Svensson, Olof; Malbet-Monaco, Stéphanie; Popov, Alexander; Nurizzo, Didier; Bowler, Matthew W.

    2015-01-01

    A fully automatic system has been developed that performs X-ray centring and characterization of, and data collection from, large numbers of cryocooled crystals without human intervention. Considerable effort is dedicated to evaluating macromolecular crystals at synchrotron sources, even for well established and robust systems. Much of this work is repetitive, and the time spent could be better invested in the interpretation of the results. In order to decrease the need for manual intervention in the most repetitive steps of structural biology projects, initial screening and data collection, a fully automatic system has been developed to mount, locate, centre to the optimal diffraction volume, characterize and, if possible, collect data from multiple cryocooled crystals. Using the capabilities of pixel-array detectors, the system is as fast as a human operator, taking an average of 6 min per sample depending on the sample size and the level of characterization required. Using a fast X-ray-based routine, samples are located and centred systematically at the position of highest diffraction signal and important parameters for sample characterization, such as flux, beam size and crystal volume, are automatically taken into account, ensuring the calculation of optimal data-collection strategies. The system is now in operation at the new ESRF beamline MASSIF-1 and has been used by both industrial and academic users for many different sample types, including crystals of less than 20 µm in the smallest dimension. To date, over 8000 samples have been evaluated on MASSIF-1 without any human intervention

  8. Fully automatic characterization and data collection from crystals of biological macromolecules

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Olof; Malbet-Monaco, Stéphanie; Popov, Alexander; Nurizzo, Didier, E-mail: nurizzo@esrf.fr [European Synchrotron Radiation Facility, 71 Avenue des Martyrs, CS 40220, 38043 Grenoble (France); Bowler, Matthew W., E-mail: nurizzo@esrf.fr [European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble (France); Université Grenoble Alpes–EMBL–CNRS, Grenoble Outstation, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble (France); European Synchrotron Radiation Facility, 71 Avenue des Martyrs, CS 40220, 38043 Grenoble (France)

    2015-07-31

    A fully automatic system has been developed that performs X-ray centring and characterization of, and data collection from, large numbers of cryocooled crystals without human intervention. Considerable effort is dedicated to evaluating macromolecular crystals at synchrotron sources, even for well established and robust systems. Much of this work is repetitive, and the time spent could be better invested in the interpretation of the results. In order to decrease the need for manual intervention in the most repetitive steps of structural biology projects, initial screening and data collection, a fully automatic system has been developed to mount, locate, centre to the optimal diffraction volume, characterize and, if possible, collect data from multiple cryocooled crystals. Using the capabilities of pixel-array detectors, the system is as fast as a human operator, taking an average of 6 min per sample depending on the sample size and the level of characterization required. Using a fast X-ray-based routine, samples are located and centred systematically at the position of highest diffraction signal and important parameters for sample characterization, such as flux, beam size and crystal volume, are automatically taken into account, ensuring the calculation of optimal data-collection strategies. The system is now in operation at the new ESRF beamline MASSIF-1 and has been used by both industrial and academic users for many different sample types, including crystals of less than 20 µm in the smallest dimension. To date, over 8000 samples have been evaluated on MASSIF-1 without any human intervention.

  9. Fully automatic characterization and data collection from crystals of biological macromolecules.

    Science.gov (United States)

    Svensson, Olof; Malbet-Monaco, Stéphanie; Popov, Alexander; Nurizzo, Didier; Bowler, Matthew W

    2015-08-01

    Considerable effort is dedicated to evaluating macromolecular crystals at synchrotron sources, even for well established and robust systems. Much of this work is repetitive, and the time spent could be better invested in the interpretation of the results. In order to decrease the need for manual intervention in the most repetitive steps of structural biology projects, initial screening and data collection, a fully automatic system has been developed to mount, locate, centre to the optimal diffraction volume, characterize and, if possible, collect data from multiple cryocooled crystals. Using the capabilities of pixel-array detectors, the system is as fast as a human operator, taking an average of 6 min per sample depending on the sample size and the level of characterization required. Using a fast X-ray-based routine, samples are located and centred systematically at the position of highest diffraction signal and important parameters for sample characterization, such as flux, beam size and crystal volume, are automatically taken into account, ensuring the calculation of optimal data-collection strategies. The system is now in operation at the new ESRF beamline MASSIF-1 and has been used by both industrial and academic users for many different sample types, including crystals of less than 20 µm in the smallest dimension. To date, over 8000 samples have been evaluated on MASSIF-1 without any human intervention.

  10. Crystalline Hybrid Polyphenylene Macromolecules from Octaalkynylsilsesquioxanes, Crystal Structures, and a Potential Route to 3-D Graphenes

    Energy Technology Data Exchange (ETDEWEB)

    Roll, Mark F; Kampf, Jeffrey W.; Laine, Richard M

    2011-05-10

    We report here the Diels–Alder reaction of octa(diphenylacetylene)silsesquioxane [DPA₈OS] with tetraphenylcyclopentadienone or tetra(p-tolyl)cyclopentadienone to form octa(hexaphenylbenzene)octasilsesquioxane, (Ph₆C₆)₈OS, or octa(tetratolyldiphenylbenzene)octasilsesquioxane, (p-Tolyl₄Ph₂C₆)₈OS. Likewise, tetra(p-tolyl)cyclopentadienone reacts with octa(p-tolylethynylphenyl)OS to form octa(pentatolylphenylbenzene)octasilsesquioxane (p-Tolyl₅PhC₆)₈OS. These compounds, with molecular weights of 4685–5245 Da, were isolated and characterized using a variety of analytical methods. The crystal structure of DPA₈OS offers a 3 nm³ unit cell with Z = 1. The crystal structure of (Ph₆C₆)₈OS was determined to have a triclinic unit cell of 11 nm³ with Z = 1. The latter structure is believed to be the largest discrete molecular structure reported with 330 carbons. Efforts to dehydrogenatively cyclize (Scholl reaction) the hexaarylbenzene groups to form 3-D octgraphene compounds are described.

  11. Protein crystal growth on board Shenzhou 3: a concerted effort improves crystal diffraction quality and facilitates structure determination

    International Nuclear Information System (INIS)

    Han, Y.; Cang, H.-X.; Zhou, J.-X.; Wang, Y.-P.; Bi, R.-C.; Colelesage, J.; Delbaere, L.T.J.; Nahoum, V.; Shi, R.; Zhou, M.; Zhu, D.-W.; Lin, S.-X.

    2004-01-01

    The crystallization of 16 proteins was carried out using 60 wells on board Shenzhou 3 in 2002. Although the mission was only 7 days, careful and concerted planning at all stages made it possible to obtain crystals of improved quality compared to their ground controls for some of the proteins. Significantly improved resolutions were obtained from diffracted crystals of 4 proteins. A complete data set from a space crystal of the PEP carboxykinase yielded significantly higher resolution (1.46 A vs. 1.87 A), I/sigma (22.4 vs. 15.5), and a lower average temperature factor (29.2 A 2 vs. 42.9 A 2 ) than the best ground-based control crystal. The 3-D structure of the enzyme is well improved with significant ligand density. It has been postulated that the reduced convection and absence of macromolecule sedimentation under microgravity have advantages/benefits for protein crystal growth. Improvements in experimental design for protein crystal growth in microgravity are ongoing

  12. Diagram of state of stiff amphiphilic macromolecules

    NARCIS (Netherlands)

    Markov, Vladimir A.; Vasilevskaya, Valentina V.; Khalatur, Pavel G.; ten Brinke, Gerrit; Khokhlov, Alexei R.

    2007-01-01

    We studied coil-globule transitions in stiff-chain amphiphilic macromolecules via computer modeling and constructed phase diagrams for such molecules in terms of solvent quality and persistence length. We showed that the shape of the phase diagram essentially depends on the macromolecule degree of

  13. Polyacid macromolecule primers

    Science.gov (United States)

    Sugama, Toshifumi.

    1989-12-26

    Hydrophilic polyacids are described, such as macromolecules of polyitaconic acid and polyacrylic acid, where such macromolecules have molecular weights >50,000 as primers between a polymeric top coating, such as polyurethane, and an oxidized aluminum or aluminum alloy. A near monolayer of primer is used in polymeric adhesive/oxidized aluminum adhered joint systems in 0.05% primer concentration to give superior results in standard peel tests. 2 figs.

  14. Organized monolayers of biological macromolecules on Au(111) surfaces

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Chi, Qijin; Nielsen, Jens Ulrik

    2002-01-01

    Single-crystal electrochemistry and scanning tunneling microscopy directly in aqueous electrolyte solution (in situ STM) are established in physical electrochemistry but new in studies of adsorption and interfacial electrochemistry of biological macromolecules. These high-resolution techniques ha...

  15. High-quality bulk hybrid perovskite single crystals within minutes by inverse temperature crystallization

    KAUST Repository

    Saidaminov, Makhsud I.

    2015-07-06

    Single crystals of methylammonium lead trihalide perovskites (MAPbX3; MA=CH3NH3+, X=Br− or I−) have shown remarkably low trap density and charge transport properties; however, growth of such high-quality semiconductors is a time-consuming process. Here we present a rapid crystal growth process to obtain MAPbX3 single crystals, an order of magnitude faster than previous reports. The process is based on our observation of the substantial decrease of MAPbX3 solubility, in certain solvents, at elevated temperatures. The crystals can be both size- and shape-controlled by manipulating the different crystallization parameters. Despite the rapidity of the method, the grown crystals exhibit transport properties and trap densities comparable to the highest quality MAPbX3 reported to date. The phenomenon of inverse or retrograde solubility and its correlated inverse temperature crystallization strategy present a major step forward for advancing the field on perovskite crystallization.

  16. Crystal quality analysis and improvement using x-ray topography

    International Nuclear Information System (INIS)

    Maj, J.; Goetze, K.; Macrander, A.; Zhong, Y.; Huang, X.; Maj, L.

    2008-01-01

    The Topography X-ray Laboratory of the Advanced Photon Source (APS) at Argonne National Laboratory operates as a collaborative effort with APS users to produce high performance crystals for APS X-ray beamline experiments. For many years the topography laboratory has worked closely with an on-site optics shop to help ensure the production of crystals with the highest quality, most stress-free surface finish possible. It has been instrumental in evaluating and refining methods used to produce high quality crystals. Topographical analysis has shown to be an effective method to quantify and determine the distribution of stresses, to help identify methods that would mitigate the stresses and improve the Rocking curve, and to create CCD images of the crystal. This paper describes the topography process and offers methods for reducing crystal stresses in order to substantially improve the crystal optics.

  17. Macromolecules in Flatland

    Science.gov (United States)

    Prasad, Ashok

    This thesis is on statistical mechanics of semiflexible polymers, and diffusion and fluid mechanics in lipid membranes. In chapter two the worm-like chain model of DNA under an applied force in two dimensions is solved analytically in terms of an expansion in Mathieu functions. An analytical expression for the force-extension relation for long polymers is computed in terms of Mathieu characteristic functions. The nematic order parameter and average extension of the polymer stretched by a strong nematic field are also derived. In chapter three the force-extension relations for short semiflexible polymers or long polymers under large forces are calculated analytically using the generating functional formalism of field theory. It is shown that boundary conditions like axis-clamping affect the force extension curves. This formalism is also applied to a charged polymer under the influence of an electric field, and analytical formulae for the force-extension relation are obtained. In chapter four the results of an experiment on the collapse of actin molecule into racquet-like structures due to the depletion interaction are reported, and the strength of the attractive interaction between actin filaments is measured. In chapter five a theoretical model of polymer diffusion in supported membranes is constructed. The velocity fields of inclusions in lipid membranes are analyzed and it is found that inclusions create domains of entrained lipids of a characteristic size. The diffusion constant of a self-avoiding polymer in the membrane is calculated and it is shown that by altering the hydrodynamic length scale which sets the size of the entrained domains, the diffusive properties of the polymer changes in character from uncorrelated Rouse-like behavior to a solid disk-like behavior. The implications for the diffusion of macromolecules in plasma membranes are discussed. In chapter six the drift of a moving object in a lipid membrane is studied. The drift is a measure of the

  18. Quality evaluation of resistivity-controlled silicon crystals

    Science.gov (United States)

    Wang, Jong Hoe

    2006-01-01

    The segregation phenomenon of dopants causes a low production yield of silicon crystal that meets the resistivity tolerance required by device manufacturers. In order to control the macroscopic axial resistivity distribution in bulk crystal growth, numerous studies including continuous Czochralski method and double crucible technique have been studied. The simple B-P codoping method for improving the productivity of p-type silicon single-crystal growth by controlling axial specific resistivity distribution was proposed by Wang [Jpn. J. Appl. Phys. 43 (2004) 4079]. In this work, the quality of Czochralski-grown silicon single crystals with a diameter 200 mm using B-P codoping method was studied from the chemical and structural points of view. It was found that the characteristics of B-P codoped wafers including the oxygen precipitation behavior and the grown-in defects are same as that of conventional B-doped Czochralski crystals.

  19. Measuring Beam Quality of Hollow Core Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Shephard, J.D.; Roberts, John; Jones, J.D.C.

    2006-01-01

    In this paper, the authors measure the quality of the delivered beam from hollow core photonic crystal fibers (HC-PCFs). The$M^2$parameter is determined, and the near- to far-field transition is examined. The influence on these properties due to the presence of a core surround mode is evaluated.......17 for the same output beam. This highlights the need for careful consideration when measuring and describing the beam quality delivered by these novel photonic fibers....

  20. High-quality bulk hybrid perovskite single crystals within minutes by inverse temperature crystallization

    KAUST Repository

    Saidaminov, Makhsud I.; Abdelhady, Ahmed L.; Banavoth, Murali; Alarousu, Erkki; Burlakov, Victor M.; Peng, Wei; Dursun, Ibrahim; Wang, Lingfei; He, Yao; Maculan, Giacomo; Goriely, Alain; Wu, Tao; Mohammed, Omar F.; Bakr, Osman

    2015-01-01

    Single crystals of methylammonium lead trihalide perovskites (MAPbX3; MA=CH3NH3+, X=Br− or I−) have shown remarkably low trap density and charge transport properties; however, growth of such high-quality semiconductors is a time-consuming process

  1. High-quality PWO crystals for the PANDA-EMC

    International Nuclear Information System (INIS)

    Novotny, R W; Bremer, D; Dormenev, V; Drexler, P; Eissner, T; Kuske, T; Moritz, M

    2011-01-01

    The paper provides a status report on the crystal production and quality control of a major part of the PbWO 4 crystals for the PANDA-EMC. The results confirm the excellent performance of the new generation of PWO-II. The mechanism of stimulated recovery provides an additional tool to recover radiation damage at room and low temperatures by applying an external infrared light source. Even on-line recovery can be considered if the photo sensor is insensitive in that particular wavelength region.

  2. Macromolecular crystallization in microgravity

    International Nuclear Information System (INIS)

    Snell, Edward H; Helliwell, John R

    2005-01-01

    Density difference fluid flows and sedimentation of growing crystals are greatly reduced when crystallization takes place in a reduced gravity environment. In the case of macromolecular crystallography a crystal of a biological macromolecule is used for diffraction experiments (x-ray or neutron) so as to determine the three-dimensional structure of the macromolecule. The better the internal order of the crystal then the greater the molecular structure detail that can be extracted. It is this structural information that enables an understanding of how the molecule functions. This knowledge is changing the biological and chemical sciences, with major potential in understanding disease pathologies. In this review, we examine the use of microgravity as an environment to grow macromolecular crystals. We describe the crystallization procedures used on the ground, how the resulting crystals are studied and the knowledge obtained from those crystals. We address the features desired in an ordered crystal and the techniques used to evaluate those features in detail. We then introduce the microgravity environment, the techniques to access that environment and the theory and evidence behind the use of microgravity for crystallization experiments. We describe how ground-based laboratory techniques have been adapted to microgravity flights and look at some of the methods used to analyse the resulting data. Several case studies illustrate the physical crystal quality improvements and the macromolecular structural advances. Finally, limitations and alternatives to microgravity and future directions for this research are covered. Macromolecular structural crystallography in general is a remarkable field where physics, biology, chemistry and mathematics meet to enable insight to the fundamentals of life. As the reader will see, there is a great deal of physics involved when the microgravity environment is applied to crystallization, some of it known, and undoubtedly much yet to

  3. The radiation chemistry of macromolecules

    CERN Document Server

    1973-01-01

    The Radiation Chemistry of Macromolecules, Volume II is a collection of papers that discusses radiation chemistry of specific systems. Part 1 deals with radiation chemistry of substituted vinyl polymers, particularly polypropylene (PP) as its structure is intermediate between polyethylene and polyisobutylene. This part also discusses polypropylene oxide (PPOx) for it can be prepared in the atactic, isotactic, and optically active forms. One paper focuses on the fundamental chemical processes and the changes in physical properties that give rise to many different applications of polystyrene. An

  4. Positron annihilation lifetime spectroscopy of macromolecules

    International Nuclear Information System (INIS)

    Simon, G.

    1996-01-01

    Positron annihilation lifetime spectroscopy (PALS) is a technique which makes use of the anti- particle of the electron, the positron (e + ), first predicted by Dirac in 1931. This talk will concentrate on the use of PALS as a technique in characterising macromolecules. PALS has been used by various groups to evaluate many properties that one associates with free volume such as physical ageing, gas permeability, the glass transition, uptake of a solvent, crystallinity, crosslinking, molecular mobility. One area of much interest has been the use of this technique in looking at miscibility of polymer blends. In miscible blends, the interactions of the different polymers may be expected to lead to a negative free volume of mixing because of the strong attraction between the different chains. This may influence the free volume properties. Conversely, if a material is partially miscible or totally immiscible, this should influence both the size and total content of free volume. This should be related to other properties such as mechanical properties and molecular mobility, such as measured by dielectric relaxation spectroscopy. Variations on this involve copolymerization of crosslinked materials or linear thermoplastics (the ultimate 'molecular' miscibility) and this will also be discussed. Multiphase systems such as water uptake in polymers can vary polymer properties by filling molecular voids, as well as disturbing chain conformations and, in the case of polar polymers, associating with the polymer chains. The effect of polymer molecular structure on free volume - particularly in rigid polymer chains such as substituted poly(phenylenes) and liquid crystalline polymers will also be presented. Indeed, the unusual packing which arises from such anisotropic molecules leads to unusual behaviours both of the homolpolymers and subsequent liquid crystal polymer - liquid crystal polymer blends

  5. Rigidity of Glasses and Macromolecules

    Science.gov (United States)

    Thorpe, M. F.

    1998-03-01

    The simple yet powerful ideas of percolation theory have found their way into many different areas of research. In this talk we show how RIGIDITY PERCOLATION can be studied at a similar level of sophistication, using a powerful new program THE PEBBLE GAME (D. J. Jacobs and M. F. Thorpe, Phys. Rev. E) 53, 3682 (1996). that uses an integer algorithm. This program can analyse the rigidity of two and three dimensional networks containing more than one million bars and joints. We find the total number of floppy modes, and find the critical behavior as the network goes from floppy to rigid as more bars are added. We discuss the relevance of this work to network glasses, and how it relates to experiments that involve the mechanical properties like hardness and elasticity of covalent glassy networks like Ge_xAs_ySe_1-x-y and dicuss recent experiments that suggest that the rigidity transition may be first order (Xingwei Feng, W. J.Bresser and P. Boolchand, Phys. Rev. Lett 78), 4422 (1997).. This approach is also useful in macromolecules and proteins, where detailed information about the rigid domain structure can be obtained.

  6. Controlling Vapor Pressure In Hanging-Drop Crystallization

    Science.gov (United States)

    Carter, Daniel C.; Smith, Robbie

    1988-01-01

    Rate of evaporation adjusted to produce larger crystals. Device helps to control vapor pressure of water and other solvents in vicinity of hanging drop of solution containing dissolved enzyme protein. Well of porous frit (sintered glass) holds solution in proximity to drop of solution containing protein or enzyme. Vapor from solution in frit controls evaporation of solvent from drop to control precipitation of protein or enzyme. With device, rate of nucleation limited to decrease number and increase size (and perhaps quality) of crystals - large crystals of higher quality needed for x-ray diffraction studies of macromolecules.

  7. Improvement in the quality of hematopoietic prostaglandin D synthase crystals in a microgravity environment

    International Nuclear Information System (INIS)

    Tanaka, Hiroaki; Tsurumura, Toshiharu; Aritake, Kosuke; Furubayashi, Naoki; Takahashi, Sachiko; Yamanaka, Mari; Hirota, Erika; Sano, Satoshi; Sato, Masaru; Kobayashi, Tomoyuki; Tanaka, Tetsuo; Inaka, Koji; Urade, Yoshihiro

    2011-01-01

    Crystals of hematopoietic prostaglandin D synthase grown in microgravity show improved quality. Human hematopoietic prostaglandin synthase, one of the better therapeutic target enzymes for allergy and inflammation, was crystallized with 22 inhibitors and in three inhibitor-free conditions in microgravity. Most of the space-grown crystals showed better X-ray diffraction patterns than the terrestrially grown ones, indicating the advantage of a microgravity environment on protein crystallization, especially in the case of this protein

  8. High-quality single crystals for neutron experiments

    Indian Academy of Sciences (India)

    studies and our collaborative research projects with other UK and international groups will be discussed. Keywords. Crystal growth; floating zone method; neutron scattering. ... of single crystals of new materials is a highly competitive business.

  9. Performance of ACCOS, an automatic crystal quality control system for the PWO crystals of the CMS calorimeter

    CERN Document Server

    Auffray, Etiennette; Freire, M; Lecoq, P; Le Goff, J M; Marcos, R; Drobychev, G Yu; Missevitch, O V; Oskine, A; Zouevski, R F; Peigneux, J P; Schneegans, M

    2001-01-01

    Nearly 80000 PWO crystals for the CMS electromagnetic calorimeter will arrive at CERN/Geneva and INFN-ENEA/Rome between now and year 2004. The stringent specifications on their dimensions and optical quality have to be verified prior to their formal acceptation. Automatic systems for measuring the critical parameters of each crystal and recording them in a database have been designed and constructed. The first machine is now in stable operation at CERN. In this note, the performance of each instrument, based on the measurements on ~1000 pre-production crystals, is analysed in terms of stability and compared to the results of conventional benches. (9 refs).

  10. Complex formation ions calcium with macromolecules pectin

    International Nuclear Information System (INIS)

    Khalikova, M.D.; Avloev, Kh.Kh.; Muhiddinov, Z.K.

    2005-01-01

    In clause the mechanism of sorption of ions of calcium by macromolecules of pectin is opened. Is shown, that the linkage of ions of calcium descends on acid bunches of pectin, and process carries cooperative character

  11. Investigation of the influence of crystal quality on Borrmann spectroscopy

    International Nuclear Information System (INIS)

    Kalaydzhyan, Aram

    2012-12-01

    The goal of thesis is to apply the dynamical theory of X-ray diffraction for perfect crystals to mosaic crystals, which are composed of slightly misoriented blocks. For this purpose statistical methods were used for the description of crystal defects. This concept was combined with the diffraction theory and implemented in code. This program was used for numerical simulations of diffraction processes in transmission geometry by plane barium titanate crystals. The computed dependencies on defects for Borrmann spectroscopy satisfy the initial expectations for medium orders of crystal defects qualitatively.

  12. Investigation of the influence of crystal quality on Borrmann spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kalaydzhyan, Aram

    2012-12-15

    The goal of thesis is to apply the dynamical theory of X-ray diffraction for perfect crystals to mosaic crystals, which are composed of slightly misoriented blocks. For this purpose statistical methods were used for the description of crystal defects. This concept was combined with the diffraction theory and implemented in code. This program was used for numerical simulations of diffraction processes in transmission geometry by plane barium titanate crystals. The computed dependencies on defects for Borrmann spectroscopy satisfy the initial expectations for medium orders of crystal defects qualitatively.

  13. Cross-Calibration of Two Automatic Quality Control Systems for the CMS ECAL Crystals

    CERN Document Server

    Auffray, Etiennette; Chevenier, Guy; Lecoq, Paul; Perez-Prado, P; Schneegans, Marc; Sempere-Roldan, P

    2003-01-01

    The barrel part of the CMS electromagnetic calorimeter consists of about 60000 PWO crystals and will be assembled in two Regional Centers, nearby Rome and at CERN. Two automatic machines have been designed to check the crystal quality before assembly. The main crystal characteristics are compared to a set of specifications included in the contract with the crystal producers. The stability and intercalibration between the two is a fundamental issue, which has to be controlled during the whole construction phase. This paper describes the checks that were made in order to cross calibrate the measurements and to guarantee a proper selection of crystals for the detector.

  14. Approach for growth of high-quality and large protein crystals

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, Hiroyoshi, E-mail: matsumura@chem.eng.osaka-u.ac.jp [Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan); JST (Japan); SOSHO Inc., Osaka 541-0053 (Japan); Sugiyama, Shigeru; Hirose, Mika; Kakinouchi, Keisuke; Maruyama, Mihoko; Murai, Ryota [Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan); JST (Japan); Adachi, Hiroaki; Takano, Kazufumi [Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan); JST (Japan); SOSHO Inc., Osaka 541-0053 (Japan); Murakami, Satoshi [JST (Japan); SOSHO Inc., Osaka 541-0053 (Japan); Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 226-8501 (Japan); Mori, Yusuke; Inoue, Tsuyoshi [Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan); JST (Japan); SOSHO Inc., Osaka 541-0053 (Japan)

    2011-01-01

    Three crystallization methods, including crystallization in the presence of a semi-solid agarose gel, top-seeded solution growth (TSSG) and a large-scale hanging-drop method, have previously been presented. In this study, crystallization has been further evaluated in the presence of a semi-solid agarose gel by crystallizing additional proteins. A novel crystallization method combining TSSG and the large-scale hanging-drop method has also been developed. Three crystallization methods for growing large high-quality protein crystals, i.e. crystallization in the presence of a semi-solid agarose gel, top-seeded solution growth (TSSG) and a large-scale hanging-drop method, have previously been presented. In this study the effectiveness of crystallization in the presence of a semi-solid agarose gel has been further evaluated by crystallizing additional proteins in the presence of 2.0% (w/v) agarose gel, resulting in complete gelification with high mechanical strength. In TSSG the seed crystals are hung by a seed holder protruding from the top of the growth vessel to prevent polycrystallization. In the large-scale hanging-drop method, a cut pipette tip was used to maintain large-scale droplets consisting of protein–precipitant solution. Here a novel crystallization method that combines TSSG and the large-scale hanging-drop method is reported. A large and single crystal of lysozyme was obtained by this method.

  15. Molecular Imprinting of Macromolecules for Sensor Applications.

    Science.gov (United States)

    Saylan, Yeşeren; Yilmaz, Fatma; Özgür, Erdoğan; Derazshamshir, Ali; Yavuz, Handan; Denizli, Adil

    2017-04-19

    Molecular recognition has an important role in numerous living systems. One of the most important molecular recognition methods is molecular imprinting, which allows host compounds to recognize and detect several molecules rapidly, sensitively and selectively. Compared to natural systems, molecular imprinting methods have some important features such as low cost, robustness, high recognition ability and long term durability which allows molecularly imprinted polymers to be used in various biotechnological applications, such as chromatography, drug delivery, nanotechnology, and sensor technology. Sensors are important tools because of their ability to figure out a potentially large number of analytical difficulties in various areas with different macromolecular targets. Proteins, enzymes, nucleic acids, antibodies, viruses and cells are defined as macromolecules that have wide range of functions are very important. Thus, macromolecules detection has gained great attention in concerning the improvement in most of the studies. The applications of macromolecule imprinted sensors will have a spacious exploration according to the low cost, high specificity and stability. In this review, macromolecules for molecularly imprinted sensor applications are structured according to the definition of molecular imprinting methods, developments in macromolecular imprinting methods, macromolecular imprinted sensors, and conclusions and future perspectives. This chapter follows the latter strategies and focuses on the applications of macromolecular imprinted sensors. This allows discussion on how sensor strategy is brought to solve the macromolecules imprinting.

  16. Quality inspection of anisotropic scintillating crystals through measurement of interferometric fringe pattern parameters

    CERN Document Server

    Cocozzella, N; Majni, G; Paone, N; Rinaldi, D T

    2001-01-01

    Scintillating crystals are widely used as detectors in radiographic systems, computerized axial tomography devices and in calorimeters employed in high-energy physics. This paper results from a project motivated by the development of the CMS calorimeter at CERN, which will make use of a large number of scintillating crystals. In order to prevent crystals from breaking because of internal residual stress, a quality control system based on optic inspection of interference fringe patterns was developed. The principle of measurement procedures was theoretically modelled, and then a dedicated polariscope was designed and built, in order to observe the crystals under induced stresses or to evaluate the residual internal stresses. The results are innovative and open a new perspective for scintillating crystals quality control: the photoelastic constant normal to the optic axis of the lead tungstate crystals (PbWO sub 4) was measured, and the inspection procedure developed is applicable to mass production, not only t...

  17. System for determining sizes of biological macromolecules

    International Nuclear Information System (INIS)

    Nelson, R.M.; Danby, P.C.

    1987-01-01

    An electrophoresis system for determining the sizes of radiolabelled biological macromolecules is described. It comprises a cell containing an electrophoresis gel and having at least one lane, a voltage source connected across the gel for effecting the movement of macromolecules in the lane, a detector fixed relative to the moving molecules for generating electrical pulses responsive to signals emitted by the radiolabelled molecules; a pulse processor for counting the pulse rate, and a computational device for comparing the pulse rate to a predetermined value. (author)

  18. Effect of leucine-to-methionine substitutions on the diffraction quality of histone chaperone SET/TAF-Ibeta/INHAT crystals.

    Science.gov (United States)

    Senda, Miki; Muto, Shinsuke; Horikoshi, Masami; Senda, Toshiya

    2008-10-01

    One of the most frequent problems in crystallization is poor quality of the crystals. In order to overcome this obstacle several methods have been utilized, including amino-acid substitutions of the target protein. Here, an example is presented of crystal-quality improvement by leucine-to-methionine substitutions. A variant protein with three amino-acid substitutions enabled improvement of the crystal quality of the histone chaperone SET/TAF-Ibeta/INHAT when combined with optimization of the cryoconditions. This procedure improved the resolution of the SET/TAF-Ibeta/INHAT crystals from around 5.5 to 2.3 A without changing the crystallization conditions.

  19. Surface quality inspection of PbWO4 crystals by grazing incidence X-ray diffraction

    International Nuclear Information System (INIS)

    Mengucci, P.; Di Cristoforo, A.; Lebeau, M.; Majni, G.; Paone, N.; Pietroni, P.; Rinaldi, D.

    2005-01-01

    High-quality scintillating crystals are required for applications in radiographic systems and high-energy physics detectors to achieve the specified optical properties. In order to study the state of the single crystals surface we propose the use of the grazing incidence X-ray diffraction (GID) technique. This technique allows performing a depth profiling of the sample by changing the incidence angle of the X-ray beam with respect to the sample surface. In this work, two samples of a large PbWO 4 (PWO) single crystal exhibiting different surface roughness values have been studied. Results have shown that GID is a suitable technique for surface quality inspection

  20. Dramatic improvement of crystal quality for low-temperature-grown rabbit muscle aldolase

    International Nuclear Information System (INIS)

    Park, HaJeung; Rangarajan, Erumbi S.; Sygusch, Jurgen; Izard, Tina

    2010-01-01

    Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA–LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 Å Bragg spacing and structure determination. Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA–LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 Å Bragg spacing and structure determination. It was concluded that the improvement of crystal quality as indicated by the higher resolution of the new RMA–LC4 complex crystals was a consequence of the introduction of new lattice contacts at lower temperature. The lattice contacts corresponded to an increased number of interactions between high-entropy side chains that mitigate the lattice strain incurred upon cryocooling and accompanying mosaic spread increases. The thermodynamically unfavorable immobilization of high-entropy side chains used in lattice formation was compensated by an entropic increase in the bulk-solvent content owing to the greater solvent content of the crystal lattice

  1. Quality Assurance on Undoped CsI Crystals for the Mu2e Experiment

    Science.gov (United States)

    Atanov, N.; Baranov, V.; Budagov, J.; Davydov, Yu. I.; Glagolev, V.; Tereshchenko, V.; Usubov, Z.; Cervelli, F.; Di Falco, S.; Donati, S.; Morescalchi, L.; Pedreschi, E.; Pezzullo, G.; Raffaelli, F.; Spinella, F.; Colao, F.; Cordelli, M.; Corradi, G.; Diociaiuti, E.; Donghia, R.; Giovannella, S.; Happacher, F.; Martini, M.; Miscetti, S.; Ricci, M.; Saputi, A.; Sarra, I.; Echenard, B.; Hitlin, D. G.; Hu, C.; Miyashita, T.; Porter, F.; Zhang, L.; Zhu, R.-Y.; Grancagnolo, F.; Tassielli, G.; Murat, P.

    2018-02-01

    The Mu2e experiment is constructing a calorimeter consisting of 1,348 undoped CsI crystals in two disks. Each crystal has a dimension of 34 x 34 x 200 mm, and is readout by a large area silicon PMT array. A series of technical specifications was defined according to physics requirements. Preproduction CsI crystals were procured from three firms: Amcrys, Saint-Gobain and Shanghai Institute of Ceramics. We report the quality assurance on crystal's scintillation properties and their radiation hardness against ionization dose and neutrons. With a fast decay time of 30 ns and a light output of more than 100 p.e./MeV measured with a bi-alkali PMT, undoped CsI crystals provide a cost-effective solution for the Mu2e experiment.

  2. Modeling the Color Image and Video Quality on Liquid Crystal Displays with Backlight Dimming

    DEFF Research Database (Denmark)

    Korhonen, Jari; Mantel, Claire; Burini, Nino

    2013-01-01

    Objective image and video quality metrics focus mostly on the digital representation of the signal. However, the display characteristics are also essential for the overall Quality of Experience (QoE). In this paper, we use a model of a backlight dimming system for Liquid Crystal Display (LCD......) and show how the modeled image can be used as an input to quality assessment algorithms. For quality assessment, we propose an image quality metric, based on Peak Signal-to-Noise Ratio (PSNR) computation in the CIE L*a*b* color space. The metric takes luminance reduction, color distortion and loss...

  3. Conformational properties of rigid-chain amphiphilic macromolecules : The phase diagram

    NARCIS (Netherlands)

    Markov, V. A.; Vasilevskaya, V. V.; Khalatur, P. G.; ten Brinke, G.; Khokhlov, A. R.

    The coil-globule transition in rigid-chain amphiphilic macromolecules was studied by means of computer simulation, and the phase diagrams for such molecules in the solvent quality-persistence length coordinates were constructed. It was shown that the type of phase diagram depends to a substantial

  4. crystal

    Science.gov (United States)

    Yu, Yi; Huang, Yisheng; Zhang, Lizhen; Lin, Zhoubin; Sun, Shijia; Wang, Guofu

    2014-07-01

    A Nd3+:Na2La4(WO4)7 crystal with dimensions of ϕ 17 × 30 mm3 was grown by the Czochralski method. The thermal expansion coefficients of Nd3+:Na2La4(WO4)7 crystal are 1.32 × 10-5 K-1 along c-axis and 1.23 × 10-5 K-1 along a-axis, respectively. The spectroscopic characteristics of Nd3+:Na2La4(WO4)7 crystal were investigated. The Judd-Ofelt theory was applied to calculate the spectral parameters. The absorption cross sections at 805 nm are 2.17 × 10-20 cm2 with a full width at half maximum (FWHM) of 15 nm for π-polarization, and 2.29 × 10-20 cm2 with a FWHM of 14 nm for σ-polarization. The emission cross sections are 3.19 × 10-20 cm2 for σ-polarization and 2.67 × 10-20 cm2 for π-polarization at 1,064 nm. The fluorescence quantum efficiency is 67 %. The quasi-cw laser of Nd3+:Na2La4(WO4)7 crystal was performed. The maximum output power is 80 mW. The slope efficiency is 7.12 %. The results suggest Nd3+:Na2La4(WO4)7 crystal as a promising laser crystal fit for laser diode pumping.

  5. Angle-resolved reflection spectroscopy of high-quality PMMA opal crystal

    Science.gov (United States)

    Nemtsev, Ivan V.; Tambasov, Igor A.; Ivanenko, Alexander A.; Zyryanov, Victor Ya.

    2018-02-01

    PMMA opal crystal was prepared by a simple hybrid method, which includes sedimentation, meniscus formation and evaporation. We investigated three surfaces of this crystal by angle-resolved reflective light spectroscopy and SEM study. The angle-resolved reflective measurements were carried out in the 400-1100 nm range. We have determined the high-quality ordered surface of the crystal region. Narrow particle size distribution of the surface has been revealed. The average particle diameter obtained with SEM was nearly 361 nm. The most interesting result was that reflectivity of the surface turned out up to 98% at normal light incidence. Using a fit of dependences of the maximum reflectivity wavelength from an angle based on the Bragg-Snell law, the wavelength of maximum 0° reflectivity, the particle diameter and the fill factor have been determined. For the best surface maximum reflectivity wavelength of a 0° angle was estimated to be 869 nm. The particle diameter and fill factor were calculated as 372 nm and 0.8715, respectively. The diameter obtained by fitting is in excellent agreement with the particle diameter obtained with SEM. The reflectivity maximum is assumed to increase significantly when increasing the fill factor. We believe that using our simple approach to manufacture PMMA opal crystals will significantly increase the fabrication of high-quality photonic crystal templates and thin films.

  6. Dramatic improvement of crystal quality for low-­temperature-grown rabbit muscle aldolase

    Science.gov (United States)

    Park, HaJeung; Rangarajan, Erumbi S.; Sygusch, Jurgen; Izard, Tina

    2010-01-01

    Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA–LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 Å Bragg spacing and structure determination. It was concluded that the improvement of crystal quality as indicated by the higher resolution of the new RMA–LC4 complex crystals was a consequence of the introduction of new lattice contacts at lower temperature. The lattice contacts corresponded to an increased number of interactions between high-entropy side chains that mitigate the lattice strain incurred upon cryocooling and accompanying mosaic spread increases. The thermodynamically unfavorable immobilization of high-entropy side chains used in lattice formation was compensated by an entropic increase in the bulk-solvent content owing to the greater solvent content of the crystal lattice. PMID:20445268

  7. Dramatic Improvement of Crystal Quality for Low-temperature-grown Rabbit Muscle Aldolase

    Energy Technology Data Exchange (ETDEWEB)

    Park, H.; Rangarajan, E; Sygusch, J; Izard, T

    2010-01-01

    Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA-LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 {angstrom} Bragg spacing and structure determination. It was concluded that the improvement of crystal quality as indicated by the higher resolution of the new RMA-LC4 complex crystals was a consequence of the introduction of new lattice contacts at lower temperature. The lattice contacts corresponded to an increased number of interactions between high-entropy side chains that mitigate the lattice strain incurred upon cryocooling and accompanying mosaic spread increases. The thermodynamically unfavorable immobilization of high-entropy side chains used in lattice formation was compensated by an entropic increase in the bulk-solvent content owing to the greater solvent content of the crystal lattice.

  8. Dramatic improvement of crystal quality for low-temperature-grown rabbit muscle aldolase.

    Science.gov (United States)

    Park, Hajeung; Rangarajan, Erumbi S; Sygusch, Jurgen; Izard, Tina

    2010-05-01

    Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA-LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 A Bragg spacing and structure determination. It was concluded that the improvement of crystal quality as indicated by the higher resolution of the new RMA-LC4 complex crystals was a consequence of the introduction of new lattice contacts at lower temperature. The lattice contacts corresponded to an increased number of interactions between high-entropy side chains that mitigate the lattice strain incurred upon cryocooling and accompanying mosaic spread increases. The thermodynamically unfavorable immobilization of high-entropy side chains used in lattice formation was compensated by an entropic increase in the bulk-solvent content owing to the greater solvent content of the crystal lattice.

  9. Improvement of seawater salt quality by hydro-extraction and re-crystallization methods

    Science.gov (United States)

    Sumada, K.; Dewati, R.; Suprihatin

    2018-01-01

    Indonesia is one of the salt producing countries that use sea water as a source of raw materials, the quality of salt produced is influenced by the quality of sea water. The resulting average salt quality contains 85-90% NaCl. The Indonesian National Standard (SNI) for human salt’s consumption sodium chloride content is 94.7 % (dry base) and for industrial salt 98,5 %. In this study developed the re-crystallization without chemical and hydro-extraction method. The objective of this research to choose the best methods based on efficiency. The results showed that re-crystallization method can produce salt with NaCl content 99,21%, while hydro-extraction method content 99,34 % NaCl. The salt produced through both methods can be used as a consumption and industrial salt, Hydro-extraction method is more efficient than re-crystallization method because re-crystallization method requires heat energy.

  10. Enhanced magnetoresistance in the binary semimetal NbAs2 due to improved crystal quality

    Science.gov (United States)

    Yokoi, K.; Murakawa, H.; Komada, M.; Kida, T.; Hagiwara, M.; Sakai, H.; Hanasaki, N.

    2018-02-01

    We have observed an extremely large magnetoresistance exceeding 1.9 million at 1.7 K at 40 T for a single crystal of the binary semimetal NbAs2. The magnetoresistive behavior for this compound is quantitatively reproduced by a semiclassical two-carrier model in which the significant enhancement of magnetoresistance is attributed to the almost full compensation of the hole and electron densities (0.994 6 ×105cm2 /V .s ). Our results indicate that binary semimetals with higher carrier densities have a great potential for exhibiting a further divergent increase in magnetoresistance merely through an improvement in crystal quality.

  11. Quality control of dosimetric systems using thermoluminescent crystals

    International Nuclear Information System (INIS)

    Mahecha, L.; Plazas, M. C.; Machado, M.; Perea, M. D.

    2006-01-01

    To achieve an optimal tumoral control to prostate cancer in early and locally advanced stages, it is necessary to increase the dose with a low mobility probability at the vesicle an rectal level. This is achieved through conformal radiotherapy. The Instituto Nacional de Cancerologia uses this technique, but two questions arise from the medical-physicists and medical radio-oncologist: In accordance with clinical protocols, the conformal radiotherapy delivers a low dose to the adjacent healthy tissues. What experimental method exists that can prove with certainly the veracity of this affirmation?. And, Do the dosimetric simulation system calculate suitable the dose for each tissues?. Through thermoluminescent dosimetry and the use of a physical simulator,we measured the absorbed dose at the target volume and the adjacent tissues using conformal and conventional radiotherapy. We proved that organs such as the rectum and bladder, receiver a minor dose in conformal radiotherapy, hence reducing their mobility probability. In addition, the readings from the thermoluminescent dosimeters and the doses calculated by the ECLIPSE dosimetric system were compared, concluding that the patient's prescribed dose is effectively delivered as recommended by the quality control program in radiotherapy. (Author)

  12. High-quality single crystal growth and magnetic property of Mn4Ta2O9

    Science.gov (United States)

    Cao, Yiming; Xu, Kun; Yang, Ya; Yang, Wangfan; Zhang, Yuanlei; Kang, Yanru; He, Xijia; Zheng, Anmin; Liu, Mian; Wei, Shengxian; Li, Zhe; Cao, Shixun

    2018-06-01

    A large-size single crystal of Mn4Ta2O9 with ∼3.5 mm in diameter and ∼65 mm in length was successfully grown for the first time by a newly designed one-step method based on the optical floating zone technique. Both the clear Laue spots and sharp XRD Bragg reflections suggest the high quality of the single crystal. In Mn4Ta2O9 single crystal, an antiferromagnetic phase transition was observed below Néel temperature 102 K along c axis, which is similar to the isostructural compound Mn4Nb2O9, but differs from the isostructural Co4Nb2O9. Relative dielectric constant at 30 kOe suggests that no magnetoelectric coupling exists in Mn4Ta2O9.

  13. Controlled doping by self-assembled dendrimer-like macromolecules

    Science.gov (United States)

    Wu, Haigang; Guan, Bin; Sun, Yingri; Zhu, Yiping; Dan, Yaping

    2017-02-01

    Doping via self-assembled macromolecules might offer a solution for developing single atom electronics by precisely placing individual dopants at arbitrary location to meet the requirement for circuit design. Here we synthesize dendrimer-like polyglycerol macromolecules with each carrying one phosphorus atom in the core. The macromolecules are immobilized by the coupling reagent onto silicon surfaces that are pre-modified with a monolayer of undecylenic acid. Nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) are employed to characterize the synthesized macromolecules and the modified silicon surfaces, respectively. After rapid thermal annealing, the phosphorus atoms carried by the macromolecules diffuse into the silicon substrate, forming dopants at a concentration of 1017 cm-3. Low-temperature Hall effect measurements reveal that the ionization process is rather complicated. Unlike the widely reported simple ionization of phosphorus dopants, nitrogen and carbon are also involved in the electronic activities in the monolayer doped silicon.

  14. Growth of large size lithium niobate single crystals of high quality by tilting-mirror-type floating zone method

    Energy Technology Data Exchange (ETDEWEB)

    Sarker, Abdur Razzaque, E-mail: razzaque_ru2000@yahoo.com [Department of Physics, University of Rajshahi (Bangladesh)

    2016-05-15

    Large size high quality LiNbO{sub 3} single crystals were grown successfully by tilting-mirror-type floating zone (TMFZ) technique. The grown crystals were characterized by X-ray diffraction, etch pits density measurement, Impedance analysis, Vibrating sample magnetometry (VSM) and UV-Visible spectrometry. The effect of mirror tilting during growth on the structural, electrical, optical properties and defect density of the LiNbO{sub 3} crystals were investigated. It was found that the defect density in the crystals reduced for tilting the mirror in the TMFZ method. The chemical analysis revealed that the grown crystals were of high quality with uniform composition. The single crystals grown by TMFZ method contains no low-angle grain boundaries, indicating that they can be used for high efficiency optoelectronic devices. (author)

  15. Crystal quality of two-dimensional gallium telluride and gallium selenide using Raman fingerprint

    Directory of Open Access Journals (Sweden)

    Jannatul Susoma

    2017-01-01

    Full Text Available We have established Raman fingerprint of GaTe and GaSe to investigate their crystal quality. As unencapsulated, they both oxidise in ambient conditions which can be detected in their Raman analysis. X-ray photoelectron spectroscopy (XPS analysis shows a good agreement with Raman analysis. 50-nm-thick Al2O3 encapsulation layer deposited by atomic layer deposition (ALD inhibits degradation in ambient conditions.

  16. High quality self-separated GaN crystal grown on a novel nanoporous template by HVPE.

    Science.gov (United States)

    Huo, Qin; Shao, Yongliang; Wu, Yongzhong; Zhang, Baoguo; Hu, Haixiao; Hao, Xiaopeng

    2018-02-16

    In this study, a novel nanoporous template was obtained by a two-step etching process from MOCVD-GaN/Al 2 O 3 (MGA) with electrochemical etching sequentially followed by chemical wet etching. The twice-etched MOCVD-GaN/Al 2 O 3 (TEMGA) templates were utilized to grow GaN crystals by hydride vapor phase epitaxy (HVPE) method. The GaN crystals were separated spontaneously from the TEMGA template with the assistance of voids formed by the etched nanopores. Several techniques were utilized to characterize the quality of the free-standing GaN crystals obtained from the TEMGA template. Results showed that the quality of the as-obtained GaN crystals was improved obviously compared with those grown on the MGA. This convenient technique can be applied to grow high-quality free-standing GaN crystals.

  17. Noise reduction methods for nucleic acid and macromolecule sequencing

    Science.gov (United States)

    Schuller, Ivan K.; Di Ventra, Massimiliano; Balatsky, Alexander

    2018-05-08

    Methods, systems, and devices are disclosed for processing macromolecule sequencing data with substantial noise reduction. In one aspect, a method for reducing noise in a sequential measurement of a macromolecule comprising serial subunits includes cross-correlating multiple measured signals of a physical property of subunits of interest of the macromolecule, the multiple measured signals including the time data associated with the measurement of the signal, to remove or at least reduce signal noise that is not in the same frequency and in phase with the systematic signal contribution of the measured signals.

  18. Near-equilibrium chemical vapor deposition of high-quality single-crystal graphene directly on various dielectric substrates.

    Science.gov (United States)

    Chen, Jianyi; Guo, Yunlong; Jiang, Lili; Xu, Zhiping; Huang, Liping; Xue, Yunzhou; Geng, Dechao; Wu, Bin; Hu, Wenping; Yu, Gui; Liu, Yunqi

    2014-03-05

    By using near-equilibrium chemical vapor deposition, it is demonstrated that high-quality single-crystal graphene can be grown on dielectric substrates. The maximum size is about 11 μm. The carrier mobility can reach about 5650 cm(2) V(-1) s(-1) , which is comparable to those of some metal-catalyzed graphene crystals, reflecting the good quality of the graphene lattice. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Monolayer-crystal streptavidin support films provide an internal standard of cryo-EM image quality

    Energy Technology Data Exchange (ETDEWEB)

    Han, Bong-Gyoon [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Watson, Zoe [Univ. of California, Berkeley, CA (United States); Cate, Jamie H. D. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Glaeser, Robert M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2017-03-01

    Analysis of images of biotinylated Escherichia coli 70S ribosome particles, bound to streptavidin affinity grids, demonstrates that the image-quality of particles can be predicted by the image-quality of the monolayer crystalline support film. Also, the quality of the Thon rings is a good predictor of the image-quality of particles, but only when images of the streptavidin crystals extend to relatively high resolution. When the estimated resolution of streptavidin was 5 Å or worse, for example, the ribosomal density map obtained from 22,697 particles went to only 9.5 Å, while the resolution of the map reached 4.0 Å for the same number of particles, when the estimated resolution of streptavidin crystal was 4 Å or better. It thus is easy to tell which images in a data set ought to be retained for further work, based on the highest resolution seen for Bragg peaks in the computed Fourier transforms of the streptavidin component. The refined density map obtained from 57,826 particles obtained in this way extended to 3.6 Å, a marked improvement over the value of 3.9 Å obtained previously from a subset of 52,433 particles obtained from the same initial data set of 101,213 particles after 3-D classification. These results are consistent with the hypothesis that interaction with the air-water interface can damage particles when the sample becomes too thin. Finally, streptavidin monolayer crystals appear to provide a good indication of when that is the case.

  20. Effect of leucine-to-methionine substitutions on the diffraction quality of histone chaperone SET/TAF-Iβ/INHAT crystals

    International Nuclear Information System (INIS)

    Senda, Miki; Muto, Shinsuke; Horikoshi, Masami; Senda, Toshiya

    2008-01-01

    The combination of leucine-to-methionine substitutions and optimization of cryoconditions improved the resolution of histone chaperone SET/TAF-Iβ/INHAT crystals from around 5.5 to 2.3 Å without changing the crystallization conditions, allowing successful structure determination of SET/TAF-Iβ/INHAT by the multiwavelength anomalous diffraction method. One of the most frequent problems in crystallization is poor quality of the crystals. In order to overcome this obstacle several methods have been utilized, including amino-acid substitutions of the target protein. Here, an example is presented of crystal-quality improvement by leucine-to-methionine substitutions. A variant protein with three amino-acid substitutions enabled improvement of the crystal quality of the histone chaperone SET/TAF-Iβ/INHAT when combined with optimization of the cryoconditions. This procedure improved the resolution of the SET/TAF-Iβ/INHAT crystals from around 5.5 to 2.3 Å without changing the crystallization conditions

  1. Characterization of biological macromolecules by electrophoresis and neutron activation

    International Nuclear Information System (INIS)

    Stone, S.F.; Hancock, D.; Zeisler, R.

    1987-01-01

    A procedure combining polyacrylamide gel electrophoresis (PAGE) with INAA and autoradiography was developed to study biological macromolecules and their associated trace elements. Results from the application of this method to several metalloproteins are presented. (author)

  2. A general method to study equilibrium partitioning of macromolecules

    DEFF Research Database (Denmark)

    The distribution of macromolecules between a confined microscopic solution and a macroscopic bulk solution plays an important role in understanding separation processes such as Size Exclusion Chromatography (SEC). In this study, we have developed an efficient computational algorithm for obtaining...

  3. Macromolecule simulation and CH4 adsorption mechanism of coal vitrinite

    Science.gov (United States)

    Yu, Song; Yan-ming, Zhu; Wu, Li

    2017-02-01

    The microscopic mechanism of interactions between CH4 and coal macromolecules is of significant practical and theoretical importance in CBM development and methane storage. Under periodic boundary conditions, the optimal energy configuration of coal vitrinite, which has a higher torsion degree and tighter arrangement, can be determined by the calculation of molecular mechanics (MM) and molecular dynamics (MD), and annealing kinetics simulation based on ultimate analysis, 13C NMR, FT IR and HRTEM. Macromolecular stabilization is primarily due to the van der Waals energy and covalent bond energy, mainly consisting of bond torsion energy and bond angle energy. Using the optimal configuration as the adsorbent, GCMC simulation of vitrinite adsorption of CH4 is conducted. A saturated state is reached after absorbing 17 CH4s per coal vitrinite molecule. CH4 is preferentially adsorbed on the edge, and inclined to gathering around the branched chains of the inner vitrinite sites. Finally, the adsorption parameters are calculated through first principle DFT. The adsorbability order is as follows: aromatic structure> heteroatom rings > oxygen functional groups. The adsorption energy order is as follows: Top graphene. However, the energy of the most preferential location is much lower than that of graphite/graphene. CH4 is more easily absorbed on the surface of vitrinite. Adsorbability varies considerably at different adsorption locations and sites on the surface of vitrinite. Crystal parameter of vitrinite is a = b = c = 15.8 Å and majority of its micropores are blow 15.8 Å, indicating that the vitrinite have the optimum adsorption aperture. It can explain its higher observed adsorption capacities for CH4 compared with graphite/graphene.

  4. Fabrication of high-quality single-crystal Cu thin films using radio-frequency sputtering.

    Science.gov (United States)

    Lee, Seunghun; Kim, Ji Young; Lee, Tae-Woo; Kim, Won-Kyung; Kim, Bum-Su; Park, Ji Hun; Bae, Jong-Seong; Cho, Yong Chan; Kim, Jungdae; Oh, Min-Wook; Hwang, Cheol Seong; Jeong, Se-Young

    2014-08-29

    Copper (Cu) thin films have been widely used as electrodes and interconnection wires in integrated electronic circuits, and more recently as substrates for the synthesis of graphene. However, the ultra-high vacuum processes required for high-quality Cu film fabrication, such as molecular beam epitaxy (MBE), restricts mass production with low cost. In this work, we demonstrated high-quality Cu thin films using a single-crystal Cu target and radio-frequency (RF) sputtering technique; the resulting film quality was comparable to that produced using MBE, even under unfavorable conditions for pure Cu film growth. The Cu thin film was epitaxially grown on an Al2O3 (sapphire) (0001) substrate, and had high crystalline orientation along the (111) direction. Despite the 10(-3) Pa vacuum conditions, the resulting thin film was oxygen free due to the high chemical stability of the sputtered specimen from a single-crystal target; moreover, the deposited film had >5× higher adhesion force than that produced using a polycrystalline target. This fabrication method enabled Cu films to be obtained using a simple, manufacturing-friendly process on a large-area substrate, making our findings relevant for industrial applications.

  5. Analysis of phase transitions and crystal structures of novel benzothiophene derivatives

    Science.gov (United States)

    Zhang, Shuo

    Although single crystal X-ray diffraction remains the most important technique for analyzing periodically ordered structures at atomic resolution, single crystal X-ray diffraction of organic macromolecules is challenged by difficulty in growing single crystals of desired size and quality. Electron crystallography of organic macromolecules, on the other hand, is limited by image resolution due to radiation damage and highly dependent on high-resolution instrumentation. Novel alkylated benzothiophene derivatives synthesized previously can be readily fabricated into semiconductor devices for various applications (photodetectors, explosive sensors, field-effect transistors, light-emitting diodes, etc.) via solution process. The object of this research is to identify phase transitions of organic macromolecules of this kind via differential scanning calorimetry and temperature-resolved wide angle X-ray diffraction, and to determine their lattice parameters and space groups by reconstruction of their reciprocal space via transmission electron microscopy/selected area electron diffraction followed by refinement with X-ray diffraction, supplemented by polarized light microscopy. Computer simulation was performed to rationalize the molecular packing schemes, so as to understand the origin of their electronic performance from crystallographic perspective.

  6. Growth of optical-quality anthracene crystals doped with dibenzoterrylene for controlled single photon production

    Energy Technology Data Exchange (ETDEWEB)

    Major, Kyle D., E-mail: kyle.major11@imperial.ac.uk; Lien, Yu-Hung; Polisseni, Claudio; Grandi, Samuele; Kho, Kiang Wei; Clark, Alex S.; Hwang, J.; Hinds, E. A., E-mail: ed.hinds@imperial.ac.uk [Centre for Cold Matter, Department of Physics, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom)

    2015-08-15

    Dibenzoterrylene (DBT) molecules within a crystalline anthracene matrix show promise as quantum emitters for controlled, single photon production. We present the design and construction of a chamber in which we reproducibly grow doped anthracene crystals of optical quality that are several mm across and a few μm thick. We demonstrate control of the DBT concentration over the range 6–300 parts per trillion and show that these DBT molecules are stable single-photon emitters. We interpret our data with a simple model that provides some information on the vapour pressure of DBT.

  7. Low index contrast heterostructure photonic crystal cavities with high quality factors and vertical radiation coupling

    Science.gov (United States)

    Ge, Xiaochen; Minkov, Momchil; Fan, Shanhui; Li, Xiuling; Zhou, Weidong

    2018-04-01

    We report here design and experimental demonstration of heterostructure photonic crystal cavities resonating near the Γ point with simultaneous strong lateral confinement and highly directional vertical radiation patterns. The lateral confinement is provided by a mode gap originating from a gradual modulation of the hole radii. High quality factor resonance is realized with a low index contrast between silicon nitride and quartz. The near surface-normal directional emission is preserved when the size of the core region is scaled down. The influence of the cavity size parameters on the resonant modes is also investigated theoretically and experimentally.

  8. Quality inspection of anisotropic scintillating lead tungstate (PbWO 4) crystals through measurement of interferometric fringe pattern parameters

    Science.gov (United States)

    Cocozzella, N.; Lebeau, M.; Majni, G.; Paone, N.; Rinaldi, D.

    2001-08-01

    Scintillating crystals are widely used as detectors in radiographic systems, computerized axial tomography devices and in calorimeters employed in high-energy physics. This paper results from a project motivated by the development of the CMS calorimeter at CERN, which will make use of a large number of scintillating crystals. In order to prevent crystals from breaking because of internal residual stress, a quality control system based on optic inspection of interference fringe patterns was developed. The principle of measurement procedures was theoretically modelled, and then a dedicated polariscope was designed and built, in order to observe the crystals under induced stresses or to evaluate the residual internal stresses. The results are innovative and open a new perspective for scintillating crystals quality control: the photoelastic constant normal to the optic axis of the lead tungstate crystals (PbWO 4) was measured, and the inspection procedure developed is applicable to mass production, not only to optimize the crystal processing, but also to establish a quality inspection procedure.

  9. Quality inspection of anisotropic scintillating lead tungstate (PbWO4) crystals through measurement of interferometric fringe pattern parameters

    International Nuclear Information System (INIS)

    Cocozzella, N.; Lebeau, M.; Majni, G.; Paone, N.; Rinaldi, D.

    2001-01-01

    Scintillating crystals are widely used as detectors in radiographic systems, computerized axial tomography devices and in calorimeters employed in high-energy physics. This paper results from a project motivated by the development of the CMS calorimeter at CERN, which will make use of a large number of scintillating crystals. In order to prevent crystals from breaking because of internal residual stress, a quality control system based on optic inspection of interference fringe patterns was developed. The principle of measurement procedures was theoretically modelled, and then a dedicated polariscope was designed and built, in order to observe the crystals under induced stresses or to evaluate the residual internal stresses. The results are innovative and open a new perspective for scintillating crystals quality control: the photoelastic constant normal to the optic axis of the lead tungstate crystals (PbWO 4 ) was measured, and the inspection procedure developed is applicable to mass production, not only to optimize the crystal processing, but also to establish a quality inspection procedure

  10. Introduction of a leucine half-zipper engenders multiple high-quality crystals of a recalcitrant tRNA synthetase

    International Nuclear Information System (INIS)

    Guo, Min; Shapiro, Ryan; Schimmel, Paul; Yang, Xiang-Lei

    2010-01-01

    E. coli alanyl-tRNA synthetase is recalcitrant to crystallization. A group of leucine substitutions has transformed the protein. Although Escherichia coli alanyl-tRNA synthetase was among the first tRNA synthetases to be sequenced and extensively studied by functional analysis, it has proved to be recalcitrant to crystallization. This challenge remained even for crystallization of the catalytic fragment. By mutationally introducing three stacked leucines onto the solvent-exposed side of an α-helix, an engineered catalytic fragment of the synthetase was obtained that yielded multiple high-quality crystals and cocrystals with different ligands. The engineered α-helix did not form a leucine zipper that interlocked with the same α-helix from another molecule. Instead, using the created hydrophobic spine, it interacted with other surfaces of the protein as a leucine half-zipper (LHZ) to enhance the crystal lattice interactions. The LHZ made crystal lattice contacts in all crystals of different space groups. These results illustrate the power of introducing an LHZ into helices to facilitate crystallization. The authors propose that the method can be unified with surface-entropy reduction and can be broadly used for protein-surface optimization in crystallization

  11. Development of a methodology for the analysis of the crystalline quality of single crystals

    International Nuclear Information System (INIS)

    Metairon, Sabrina

    1999-01-01

    This work aims to establish a methodology for the analysis of the crystalline quality of single crystals. It is shown in the work as from neutron diffraction tridimensional rocking curves it is possible to determine the intrinsic widths at half maximum of the crystalline domains of a crystal, as well as the relative intensities of such domains and the angular distances between them. The construction of contour maps, on the bases of the tridimensional curves, make easier the determination of the above characteristics. For the development of the method, tridimensional rocking curves (I x ω x χ) have been obtained with neutrons from a barium lithium fluoride (BaLiF 3 ) and an aluminum crystal. The intensity I was obtained as rocking curves around the ω axis, with the angle % varying in a convenient interval. The individual (I x ω) and (I x χ) curves, which constitute the tridimensional rocking curve, were fitted by Gaussians and, in continuation of the process, the instrumental broadenings in directions ω and χ were deconvoluted from them. The instrumental broadenings were obtained with perfect type lithium fluoride (LiF) single crystals in the form of rocking curves around the ω and χ axes. Due to an enhanced Lorentz factor in direction χ, the scale in this direction was 'shrunk' by a correction factor in order to make the widths at half maximum of domains equivalent to those found in direction co. The contour map constructed with the deconvoluted rocking curves for BaLiF 3 , showed the existence of a 'proximity effect' that occurs when the widths at half maximum of domains have values near the value of the instrumental broadening. The contour map constructed with the deconvoluted rocking curves for aluminum, showed five domains of the mosaic type. Such domains were characterized concerning the width at half maximum, relative intensity and distance between them. (author)

  12. A technique for measuring the quality of an elliptically bent pentaerythritol [PET(002)] crystal

    Energy Technology Data Exchange (ETDEWEB)

    Haugh, M. J., E-mail: haughmj@nv.doe.gov; Jacoby, K. D. [National Security Technologies, LLC, Livermore, California 94550 (United States); Barrios, M. A.; Thorn, D.; Emig, J. A.; Schneider, M. B. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States)

    2016-11-15

    We present a technique for determining the X-ray spectral quality from each region of an elliptically curved PET(002) crystal. The investigative technique utilizes the shape of the crystal rocking curve which changes significantly as the radius of curvature changes. This unique quality information enables the spectroscopist to verify where in the spectral range that the spectrometer performance is satisfactory and where there are regions that would show spectral distortion. A collection of rocking curve measurements for elliptically curved PET(002) has been built up in our X-ray laboratory. The multi-lamellar model from the XOP software has been used as a guide and corrections were applied to the model based upon measurements. But, the measurement of R{sub I} at small radius of curvature shows an anomalous behavior; the multi-lamellar model fails to show this behavior. The effect of this anomalous R{sub I} behavior on an X-ray spectrometer calibration is calculated. It is compared to the multi-lamellar model calculation which is completely inadequate for predicting R{sub I} for this range of curvature and spectral energies.

  13. A technique for measuring the quality of an elliptically bent pentaerythritol [PET(002)] crystal

    International Nuclear Information System (INIS)

    Haugh, M. J.; Jacoby, K. D.; Barrios, M. A.; Thorn, D.; Emig, J. A.; Schneider, M. B.

    2016-01-01

    We present a technique for determining the X-ray spectral quality from each region of an elliptically curved PET(002) crystal. The investigative technique utilizes the shape of the crystal rocking curve which changes significantly as the radius of curvature changes. This unique quality information enables the spectroscopist to verify where in the spectral range that the spectrometer performance is satisfactory and where there are regions that would show spectral distortion. A collection of rocking curve measurements for elliptically curved PET(002) has been built up in our X-ray laboratory. The multi-lamellar model from the XOP software has been used as a guide and corrections were applied to the model based upon measurements. But, the measurement of R I at small radius of curvature shows an anomalous behavior; the multi-lamellar model fails to show this behavior. The effect of this anomalous R I behavior on an X-ray spectrometer calibration is calculated. It is compared to the multi-lamellar model calculation which is completely inadequate for predicting R I for this range of curvature and spectral energies.

  14. Technical and radiological image quality comparison of different liquid crystal displays for radiology

    Directory of Open Access Journals (Sweden)

    Dams FE

    2014-10-01

    Full Text Available Francina EM Dams,2 KY Esther Leung,1 Pieter HM van der Valk,2 Marc CJM Kock,2 Jeroen Bosman,1 Sjoerd P Niehof1 1Medical Physics and Technology, 2Department of Radiology, Albert Schweitzer Hospital, Dordrecht, The Netherlands Background: To inform cost-effective decisions in purchasing new medical liquid crystal displays, we compared the image quality in displays made by three manufacturers. Methods: We recruited 19 radiologists and residents to compare the image quality of four liquid crystal displays, including 3-megapixel Barco®, Eizo®, and NEC® displays and a 6-megapixel Barco display. The evaluators were blinded to the manufacturers' names. Technical assessments were based on acceptance criteria and test patterns proposed by the American Association of Physicists in Medicine. Radiological assessments were performed on images from the American Association of Physicists in Medicine Task Group 18. They included X-ray images of the thorax, knee, and breast, a computed tomographic image of the thorax, and a magnetic resonance image of the brain. Image quality was scored on an analog scale (range 0–10. Statistical analysis was performed with repeated-measures analysis of variance. Results: The Barco 3-megapixel display passed all acceptance criteria. The Eizo and NEC displays passed the acceptance criteria, except for the darkest pixel value in the grayscale display function. The Barco 6-megapixel display failed criteria for the maximum luminance response and the veiling glare. Mean radiological assessment scores were 7.8±1.1 (Barco 3-megapixel, 7.8±1.2 (Eizo, 8.1±1.0 (NEC, and 8.1±1.0 (Barco 6-megapixel. No significant differences were found between displays. Conclusion: According to the tested criteria, all the displays had comparable image quality; however, there was a three-fold difference in price between the most and least expensive displays. Keywords: data display, humans, radiographic image enhancement, user-computer interface

  15. Quality control on pre-serial Bridgman production of PbWO{sub 4} scintillating crystals by means of photoelasticity

    Energy Technology Data Exchange (ETDEWEB)

    Rinaldi, D., E-mail: d.rinaldi@univpm.i [Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio, Universita Politecnica delle Marche, via Brecce Bianche, 60131 Ancona (Italy); INFN section of Perugia (Italy); Ciriaco, A. [Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio, Universita' Politecnica delle Marche, via Brecce Bianche, 60131 Ancona (Italy); Lebeau, M. [CERN PH department, 1211 Geneva 23 (Switzerland); Paone, N. [Dipartimento di Meccanica, Universita' Politecnica delle Marche, via Brecce Bianche, 60131 Ancona (Italy)

    2010-04-11

    Residual internal stresses in PbWO{sub 4} (PWO) scintillating crystals grown by Bridgman method have been systematically studied. Residual stresses induced during growth play an important role in production yield. Cracking probability during mechanical processing as well as stable mechanical properties in finished crystal are closely related to internal stress levels. A regular production of good-quality crystals requires a fast and easy feed-back on growth parameters. Samples from a pre-serial production were analyzed in order to give the producer a quality feed-back for process optimization. By means of photoelasticity, we measured residual stress distribution in several sections along the growth axis and for typical positions in every section. The stress analysis revealed defects occurring during the crystallization process, attributed to dislocations, lattice disorientation and poly-crystallinity. This work had been prompted by the need for quality monitoring of a pre-serial production of PWO for the CMS experiment at CERN's LHC. Mapping stress levels inside the ingot volume and proposing a synthetic parameter to be used as a quality indicator, the resulting analysis should contribute to parameter optimization and improve the growth performance. The proposed method may be useful in conventional crystal production.

  16. Recent developments of high quality synthetic diamond single crystals for synchrotron X-ray monochromators

    CERN Document Server

    Freund, A K; Sellschop, J P Friedel; Burns, R C; Rebak, M

    2001-01-01

    For several years now, the ESRF, the University of the Witwatersrand and Messrs. De Beers Industrial Diamonds (Pty) Ltd. through their Diamond Research Laboratory, have pursued a development programme to assess and improve the quality of synthetic diamonds. Recently, in an effort to study the influence of nitrogen impurities on the defect structure, X-ray excited optical luminescence and spatially resolved double-crystal diffractometry were employed as new techniques. The correlation between nitrogen impurities and the raw defect structure was clearly visible. It was confirmed that concentration variations are related to lattice imperfections, where tilts are much more important than lattice constant variations. High reflectivity was observed and quite large zones of a sample bigger than 1 cm sup 2 showed to be perfect to within better than 0.5 arcsec.

  17. Sharp Absorption Peaks in THz Spectra Valuable for Crystal Quality Evaluation of Middle Molecular Weight Pharmaceuticals

    Science.gov (United States)

    Sasaki, Tetsuo; Sakamoto, Tomoaki; Otsuka, Makoto

    2018-05-01

    Middle molecular weight (MMW) pharmaceuticals (MW 400 4000) are attracting attention for their possible use in new medications. Sharp absorption peaks were observed in MMW pharmaceuticals at low temperatures by measuring with a high-resolution terahertz (THz) spectrometer. As examples, high-resolution THz spectra for amoxicillin trihydrate, atorvastatin calcium trihydrate, probucol, and α,β,γ,δ-tetrakis(1-methylpyridinium-4-yl)porphyrin p-toluenesulfonate (TMPyP) were obtained at 10 K. Typically observed as peaks with full width at half-height (FWHM) values as low as 5.639 GHz at 0.96492 THz in amoxicillin trihydrate and 8.857 GHz at 1.07974 THz for probucol, many sharp peaks of MMW pharmaceuticals could be observed. Such narrow absorption peaks enable evaluation of the crystal quality of MMW pharmaceuticals and afford sensitive detection of impurities.

  18. Development for equipment of the milk macromolecules content detection

    Science.gov (United States)

    Ding, Guochao; Li, Weimin; Shang, Tingyi; Xi, Yang; Gao, Yunli; Zhou, Zhen

    Developed an experimental device for rapid and accurate detection of milk macromolecular content. This device developed based on laser scattered through principle, the principle use of the ingredients of the scattered light and transmitted light ratio characterization of macromolecules. Peristaltic pump to achieve automatic input and output of the milk samples, designing weak signal detection amplifier circuit for detecting the ratio with ICL7650. Real-time operating system μC / OS-II is the core design of the software part of the whole system. The experimental data prove that the device can achieve a fast real-time measurement of milk macromolecules.

  19. Fluid Physics and Macromolecular Crystal Growth in Microgravity

    Science.gov (United States)

    Helliwell, John R.; Snell, Edward H.; Chayen, Naomi E.; Judge, Russell A.; Boggon, Titus J.; Pusey, M. L.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    The first protein crystallization experiment in microgravity was launched in April, 1981 and used Germany's Technologische Experimente unter Schwerelosigkeit (TEXUS 3) sounding rocket. The protein P-galactosidase (molecular weight 465Kda) was chosen as the sample with a liquid-liquid diffusion growth method. A sliding device brought the protein, buffer and salt solution into contact when microgravity was reached. The sounding rocket gave six minutes of microgravity time with a cine camera and schlieren optics used to monitor the experiment, a single growth cell. In microgravity a strictly laminar diffusion process was observed in contrast to the turbulent convection seen on the ground. Several single crystals, approx 100micron in length, were formed in the flight which were of inferior but of comparable visual quality to those grown on the ground over several days. A second experiment using the same protocol but with solutions cooled to -8C (kept liquid with glycerol antifreeze) again showed laminar diffusion. The science of macromolecular structural crystallography involves crystallization of the macromolecule followed by use of the crystal for X-ray diffraction experiments to determine the three dimensional structure of the macromolecule. Neutron protein crystallography is employed for elucidation of H/D exchange and for improved definition of the bound solvent (D20). The structural information enables an understanding of how the molecule functions with important potential for rational drug design, improved efficiency of industrial enzymes and agricultural chemical development. The removal of turbulent convection and sedimentation in microgravity, and the assumption that higher quality crystals will be produced, has given rise to the growing number of crystallization experiments now flown. Many experiments can be flown in a small volume with simple, largely automated, equipment - an ideal combination for a microgravity experiment. The term "protein crystal growth

  20. The CMS Electromagnetic Calorimeter: Results on Crystal Measurements, Quality Control and Data Management in the Rome Regional Center

    CERN Document Server

    Costantini, S

    2004-01-01

    The barrel of the CMS electromagnetic calorimeter is currently under construction and will contain 61200 PbWO4 crystals. Half of them are being fully characterized for dimensions, optical properties and light yield in the INFN-ENEA Regional Center near Rome. We describe the setup of an automatic quality control system for the crystal measurements and the present results on their qualification, as well as the REDACLE project, which has been developed to control and ease the production process. As it will not be possible to precalibrate the whole calorimeter,the crystal measurements and quality checks performed at the Regional Center will be crucial to provide a basis for fast in-situ calibration with particles. REDACLE is at the same time a fast database and a data management system, where the database and the workflow structures are decoupled, in order to obtain the best flexibility.

  1. Antimicrobial resistance challenged with metal-based antimicrobial macromolecules.

    Science.gov (United States)

    Abd-El-Aziz, Alaa S; Agatemor, Christian; Etkin, Nola

    2017-02-01

    Antimicrobial resistance threatens the achievements of science and medicine, as it deactivates conventional antimicrobial therapeutics. Scientists respond to the threat by developing new antimicrobial platforms to prevent and treat infections from these resistant strains. Metal-based antimicrobial macromolecules are emerging as an alternative to conventional platforms because they combine multiple mechanisms of action into one platform due to the distinctive properties of metals. For example, metals interact with intracellular proteins and enzymes, and catalyse various intracellular processes. The macromolecular architecture offers a means to enhance antimicrobial activity since several antimicrobial moieties can be conjugated to the scaffold. Further, these macromolecules can be fabricated into antimicrobial materials for contact-killing medical implants, fabrics, and devices. As volatilization or leaching out of the antimicrobial moieties from the macromolecular scaffold is reduced, these medical implants, fabrics, and devices can retain their antimicrobial activity over an extended period. Recent advances demonstrate the potential of metal-based antimicrobial macromolecules as effective platforms that prevent and treat infections from resistant strains. In this review these advances are thoroughly discussed within the context of examples of metal-based antimicrobial macromolecules, their mechanisms of action and biocompatibility. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Reduced adipose tissue lymphatic drainage of macromolecules in obese subjects

    DEFF Research Database (Denmark)

    Arngrim, Nanna Bjørkbom; Simonsen, L; Holst, J J

    2013-01-01

    The aim of this study was to investigate subcutaneous adipose tissue lymphatic drainage (ATLD) of macromolecules in lean and obese subjects and, furthermore, to evaluate whether ATLD may change in parallel with adipose tissue blood flow. Lean and obese male subjects were studied before and after ...... online publication, 3 July 2012; doi:10.1038/ijo.2012.98....

  3. Interactions between adsorbed macromolecules : measurements on emulsions and liquid films

    NARCIS (Netherlands)

    Vliet, van T.

    1977-01-01

    The aim of this study was to gain more insight into the factors, determining the inter- and intramolecular interactions between adsorbed macromolecules. To that end several experimental and theoretical approaches were followed, using well-defined systems. It was shown that these

  4. Chaperoning Roles of Macromolecules Interacting with Proteins in Vivo

    Directory of Open Access Journals (Sweden)

    Baik L. Seong

    2011-03-01

    Full Text Available The principles obtained from studies on molecular chaperones have provided explanations for the assisted protein folding in vivo. However, the majority of proteins can fold without the assistance of the known molecular chaperones, and little attention has been paid to the potential chaperoning roles of other macromolecules. During protein biogenesis and folding, newly synthesized polypeptide chains interact with a variety of macromolecules, including ribosomes, RNAs, cytoskeleton, lipid bilayer, proteolytic system, etc. In general, the hydrophobic interactions between molecular chaperones and their substrates have been widely believed to be mainly responsible for the substrate stabilization against aggregation. Emerging evidence now indicates that other features of macromolecules such as their surface charges, probably resulting in electrostatic repulsions, and steric hindrance, could play a key role in the stabilization of their linked proteins against aggregation. Such stabilizing mechanisms are expected to give new insights into our understanding of the chaperoning functions for de novo protein folding. In this review, we will discuss the possible chaperoning roles of these macromolecules in de novo folding, based on their charge and steric features.

  5. Adsorption of charged macromolecules at a gold electrode

    NARCIS (Netherlands)

    Kleijn, J.M.; Barten, D.; Cohen Stuart, M.A.

    2004-01-01

    Using an optical reflectometer with impinging-jet system, the adsorption from aqueous solution onto gold of three charged macromolecules has been studied: the strong linear-chain polyelectrolyte polyvinyl pyridine (PVP +), the fifth-generation poly(propylene imine) dendrimer DAB-64, which has a

  6. The influence of magnetic fields on protein crystal growth and quality; Zum Einfluss magnetischer Felder auf das Wachstum und die Qualitaet von Proteinkristallen

    Energy Technology Data Exchange (ETDEWEB)

    Meents, Alke

    2005-08-01

    Magnetic fields can affect protein crystal growth in several ways. In homogeneous magnetic fields molecules and crystallites line up themselves along the magnetic field direction due to their magnetic anisotropy. Inhomogeneous magnetic fields exert a force on diamagnetic and paramagnetic compounds towards regions of lower or higher field strength. This effect can be used to create a microgravity-like environment for diamagnetic proteins and an environment comparable to hypergravity for paramagnetic proteins. Crystallization in homogeneous magnetic fields and a microgravity-like environment are reported to have a positive effect on crystal quality. The aim of this work was to systematically investigate the effect of protein crystallization in magnetic fields on the crystal quality by comparing a large number of crystals grown under identical conditions with- and without magnetic fields. Crystal quality was determined by means of high resolution rocking-curve measurements. Furthermore in certain cases complete diffraction datasets were collected. Any possible influence of magnetic fields on the mosaicity and the quality of the diffraction data was evaluated statistically by applying Wilcoxon-Ranksum tests. To investigate the effect of protein crystallization in homogeneous magnetic fields the diamagnetic proteins Thaumatin, Trypsin, and Lysozyme and paramagnetic Myoglobin were crystallized in magnetic fields of 5 T, 8.8 T, and 15.8 T. The analysis of crystal mosaicity and quality of the diffraction data of the diamagnetic proteins did not reveal a significant influence on the crystal quality. In contrast the crystals of paramagnetic Myoglobin grew up to 14 times larger than the ones in the control experiment. In addition they had a significant lower mosaicity, and diffracted to a higher resolution than ever reported before. Special pole pieces for an existing magnet were designed and build to grow protein crystals in an inhomogeneous magnetic field The experimental

  7. Nanomechanical control of optical field and quality factor in photonic crystal structures

    Science.gov (United States)

    Cotrufo, Michele; Midolo, Leonardo; Zobenica, Žarko; Petruzzella, Maurangelo; van Otten, Frank W. M.; Fiore, Andrea

    2018-03-01

    Actively controlling the properties of localized optical modes is crucial for cavity quantum electrodynamics experiments. While several methods to tune the optical frequency have been demonstrated, the possibility of controlling the shape of the modes has scarcely been investigated. Yet an active manipulation of the mode pattern would allow direct control of the mode volume and the quality factor and therefore of the radiative processes. In this work, we propose and demonstrate a nano-optoelectromechanical device in which a mechanical displacement affects the spatial pattern of the electromagnetic field. The device is based on a double-membrane photonic crystal waveguide which, upon bending, creates a spatial modulation of the effective refractive index, resulting in an effective potential well or antiwell for the optical modes. The change in the field pattern drastically affects the optical losses: large modulations of the quality factors and dissipative coupling rates larger than 1 GHz/nm are predicted by calculations and confirmed by experiments. This concept opens new avenues in solid-state cavity quantum electrodynamics in which the field, instead of the frequency, is coupled to the mechanical motion.

  8. Comparison of the quality of single-crystal diamonds grown on two types of seed substrates by MPCVD

    Science.gov (United States)

    Zhao, Yun; Guo, Yanzhao; Lin, Liangzhen; Zheng, Yuting; Hei, Lifu; Liu, Jinlong; Wei, Junjun; Chen, Liangxian; Li, Chengming

    2018-06-01

    Microwave plasma chemical vapor deposition (MPCVD) was used to grow single-crystal diamonds on two types of single-crystal diamond seed substrates prepared by high-pressure, high-temperature (HPHT) and chemical vapor deposition (CVD) methods. The quality of diamonds grown on the different seed substrates was compared. Fluorescence characteristics showed that the sectors of the HPHT seed substrates were obviously partitioned. Raman and absorption spectra showed that the CVD seed substrate produced higher-quality crystals with fewer nitrogen impurities. X-ray topography showed that the HPHT seed substrate had obvious growth sector boundaries, inclusions, dislocations, and stacking faults. The polarization characteristics of HPHT seed substrate were obvious, and the stress distribution was not uniform. When etching HPHT and CVD seed substrates using the same parameters, the etching morphology and extent of different growth sectors of the two substrates differed. Although extended defects were inevitably formed at the interface and propagated in the CVD layer, the dislocation density of a 1 mm-thick CVD layer grown on a CVD seed substrate was only half that of a 1 mm-thick CVD layer grown on an HPHT seed substrate. Therefore, the use of CVD seed substrate enabled the growth of a relatively higher-quality CVD single-crystal diamond.

  9. Glass-embedded two-dimensional silicon photonic crystal devices with a broad bandwidth waveguide and a high quality nanocavity.

    Science.gov (United States)

    Jeon, Seung-Woo; Han, Jin-Kyu; Song, Bong-Shik; Noda, Susumu

    2010-08-30

    To enhance the mechanical stability of a two-dimensional photonic crystal slab structure and maintain its excellent performance, we designed a glass-embedded silicon photonic crystal device consisting of a broad bandwidth waveguide and a nanocavity with a high quality (Q) factor, and then fabricated the structure using spin-on glass (SOG). Furthermore, we showed that the refractive index of the SOG could be tuned from 1.37 to 1.57 by varying the curing temperature of the SOG. Finally, we demonstrated a glass-embedded heterostructured cavity with an ultrahigh Q factor of 160,000 by adjusting the refractive index of the SOG.

  10. Analysis of an industrial production suspension of Bacillus lentus subtilisin crystals by powder diffraction: a powerful quality-control tool

    DEFF Research Database (Denmark)

    Frankær, Christian Grundahl; Moroz, Olga V.; Turkenburg, Johan P.

    2014-01-01

    . A controlled crystallization experiment with a highly purified Savinase sample allowed the growth of single crystals of the form identified by XRPD; their structure was solved and refined to a resolution of 1.17 Å with an R of 9.2% and an Rfree of 11.8%. Thus, there are at least three polymorphs present...... in the production suspension, albeit with the 1ndq -like microcrystals predominating. It is shown how the two techniques can provide invaluable and complementary information for such a production suspension and it is proposed that XRPD provides an excellent quality-control tool for such suspensions....

  11. Dramatic improvement of crystal quality for low-­temperature-grown rabbit muscle aldolase

    OpenAIRE

    Park, HaJeung; Rangarajan, Erumbi S.; Sygusch, Jurgen; Izard, Tina

    2010-01-01

    Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA–LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 Å Bragg spacing and structure determination.

  12. An automatic device for the quality control of large-scale crystal's production

    CERN Document Server

    Baccaro, S; Castellani, M; Cecilia, A; Dafinei, I; Diemoz, M; Guerra, S; Longo, E; Montecchi, M; Organtini, G; Pellegrini, F

    2001-01-01

    In 1999, the construction of the electromagnetic calorimeter of the Compact Muon Solenoid (CMS) experiment started. Half of the barrel calorimeter made of 61200 lead tungstate (PWO) crystals will be assembled and tested in the Regional Centre of INFN-ENEA in Rome, Italy. Before assembling, all 30600 PWO crystals will be qualified for scintillation and radiation hardness characteristics by a specially built Automatic Crystal Control System. The measuring techniques for crystal qualification and performances of the automatic system will be discussed in this work. (11 refs).

  13. Implications of molecular heterogeneity for the cooperativity of biological macromolecules.

    Science.gov (United States)

    Solomatin, Sergey V; Greenfeld, Max; Herschlag, Daniel

    2011-06-01

    Cooperativity, a universal property of biological macromolecules, is typically characterized by a Hill slope, which can provide fundamental information about binding sites and interactions. We demonstrate, through simulations and single-molecule FRET (smFRET) experiments, that molecular heterogeneity lowers bulk cooperativity from the intrinsic value for the individual molecules. As heterogeneity is common in smFRET experiments, appreciation of its influence on fundamental measures of cooperativity is critical for deriving accurate molecular models.

  14. A structural self-regulation of functioning macromolecules

    International Nuclear Information System (INIS)

    Khristoforov, L.N.

    1998-01-01

    An approach to describing the functional structural changes of macromolecules processing the flows of low-mass agents is formulated. The latter appear as a source of a discrete noise whose defining parameters depend on structural variables. We derive a forward evolution equation and then, by adiabatic elimination, effective Fokker-Planck's equation for the structural modes. Within the dichotomous case, we discuss noise-induced nonequilibrium phase transitions reflecting the regulatory role of the structural subsystem

  15. Controlled synthesis of high-quality crystals of monolayer MoS2 for nanoelectronic device application

    DEFF Research Database (Denmark)

    Yang, Xiaonian; Li, Qiang; Hu, Guofeng

    2016-01-01

    . Monolayer MoS2 so far can be obtained by mechanical exfoliation or chemical vapor deposition (CVD). However, controllable synthesis of large area monolayer MoS2 with high quality needs to be improved and their growth mechanism requires more studies. Here we report a systematical study on controlled...... synthesis of high-quality monolayer MoS2 single crystals using low pressure CVD. Large-size monolayer MoS2 triangles with an edge length up to 405 mu m were successfully synthesized. The Raman and photoluminescence spectroscopy studies indicate high homogenous optical characteristic of the synthesized...... monolayer MoS2 triangles. The transmission electron microscopy results demonstrate that monolayer MoS2 triangles are single crystals. The back-gated field effect transistors (FETs) fabricated using the as-grown monolayer MoS2 show typical n-type semiconductor behaviors with carrier mobility up to 21.8 cm(2...

  16. Some problems of the statistical theory of polymeric lyotropic liquid crystals

    International Nuclear Information System (INIS)

    Grosberg, A.Yu.; Khokhlov, A.R.

    1980-06-01

    In this article we consider some topics of the statistical physics of liquid-crystalline phase in the solutions of stiff chain macromolecules. Among these topics are: the problem of the phase diagram for the liquid-crystalline transition in the solutions of completely stiff macromolecules (rigid rods); conditions of formation of the liquid-crystalline phase in the solutions of semiflexible macromolecules; possibility of the intramolecular liquid-crystalline ordering in semiflexible macromolecules; structure of intramolecular liquid crystals and dependence of the properties of the liquid-crystalline phase on the microstructure of the polymer chain. (author)

  17. Growth of high quality Bi2Sr2CaCu2Oy single crystals by the modified vertical Bridgman method

    International Nuclear Information System (INIS)

    Nagashima, O.; Tanaka, H.; Echizen, Y.; Kishida, S.

    2004-01-01

    We grew Bi 2 Sr 2 CaCu 2 O y (Bi-2212) single crystals by the modified vertical Bridgman (VB) method, and investigated their characteristics in order to clarify the optimum growth conditions for obtaining high-quality Bi-2212 single crystals. The Bi-2212 single crystals were grown changing pulling rates or using starting materials after pre-treatments. We found that the superconducting critical temperature (T c ) of the single crystal prepared at a slow growth rate of 0.25 mm/h was about 88 K and that the single crystals were a Bi-2212 single phase. Moreover, the single crystals grown using the starting materials pre-treated in Ar and O 2 atmospheres, had the T c of about 88 and 86 K, respectively. In addition, both of single crystals were Bi-2212 single phase

  18. Detached phenomenon: Its effect on the crystal quality of Ga{sub (1−x)}In{sub x}Sb bulk crystal grown by the VDS technique

    Energy Technology Data Exchange (ETDEWEB)

    Gadkari, Dattatray, E-mail: db.gadkari@gmail.com [Department of Physics, Mithibai College, Mumbai 400056 (India)

    2013-05-15

    Vertical directional solidification (VDS) technique is used on the combined growth principals of the conventional methods since 1994, which leads to the detached growth. For evaluation of the detached growth, five bulk ingots of indium doped gallium–antimonide GaSb:In (In = 0.5, 0.25, 0.15) have been grown – without the seed, without contact to the ampoule wall, without coating and without external pressure. The gap is attributed to compensate the differential thermal dilatation that is grown with the reduced diameter than the diameter of the ampoule. VDS experiments have been proved that the sum of the contact angle and growth angle is large enough to allow detachment without any additional pressure difference under the melt to offset hydrostatic pressure. A meniscus forms at the bottom of the melt, the capillarity effect establishes due to which spontaneous gap could be created by the melt free surface, thus no thermal shear stress and thermo-mechanical stresses at the interface. Detached grown bulk GaSb:In crystals showed superior crystal quality with the highest physical properties and mobility than the crystals grown ever. The axial and radial composition profile of the grown GaSb:In ingots showed variation ≤10%. From the conical region, dislocation density decreases in the growth direction and reaches less than 10{sup 3} cm{sup −2}. - Highlights: ► Detachment: without seed, without ampoule contact, without coating, without external pressure. ► Detached ingot growth samples showed the highest physical properties and the carrier mobility. ► Initial to final transition: in detached growth, dislocations decreases and less than 10{sup 3} cm{sup −2}. ► Detached samples: Raman spectrum shows only TO phonon (110) direction of single orientation. ► Detached ingot: FTIR shows highest transmissions % but decreases on increase doping in samples.

  19. Growth from the melt of high-quality In2O3 and Ga2O3 single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Fornari, Roberto; Galazka, Zbigniew; Uecker, Reinhard; Irmscher, Klaus [Leibniz Institute for Crystal Growth, Max-Born-Str. 2, 12489 Berlin (Germany)

    2013-07-01

    Because of their interesting properties semiconducting oxides, in particular Ga{sub 2}O{sub 3} In{sub 2}O{sub 3}, have recently received much attention. However, as they were deposited as films on hetero-substrates their quality was quite poor. The growth of high-quality bulk Ga{sub 2}O{sub 3} and In{sub 2}O{sub 3} and manufacture of the corresponding substrates can allow the deposition of high-quality epilayers with lower residual carrier density and fewer extended defects. For this reason IKZ has undertaken an effort to grow large single crystals of these oxide compounds from the melt. Transparent semiconducting Ga{sub 2}O{sub 3} single crystals with diameter of about 20 mm and 50-60 mm long were grown by the Czochralski method along the b-axis, using an Iridium crucible and a dynamic protective atmosphere to minimize the dissociation of Ga{sub 2}O{sub 3} melt and ingot. In the case of In{sub 2}O{sub 3} the Czochralski technique is not applicable and it was necessary to develop a novel melt growth method. This new method indeed supplied crystals from which oriented substrates could be prepared. In this presentation the melt growth of Ga{sub 2}O{sub 3} and In{sub 2}O{sub 3} single crystals will be reviewed. An important feature of both materials is given by their strong sensitivity to thermal processing: the free carrier concentration and the absorption spectra drastically vary as a function of annealing temperature, duration and ambient. The possible causes are discussed.

  20. Optimization of the Critical Parameters of the Spherical Agglomeration Crystallization Method by the Application of the Quality by Design Approach

    Directory of Open Access Journals (Sweden)

    Orsolya Gyulai

    2018-04-01

    Full Text Available This research work presents the use of the Quality by Design (QbD concept for optimization of the spherical agglomeration crystallization method in the case of the active agent, ambroxol hydrochloride (AMB HCl. AMB HCl spherical crystals were formulated by the spherical agglomeration method, which was applied as an antisolvent technique. Spherical crystals have good flowing properties, which makes the direct compression tableting method applicable. This means that the amount of additives used can be reduced and smaller tablets can be formed. For the risk assessment, LeanQbD Software was used. According to its results, four independent variables (mixing type and time, dT (temperature difference between solvent and antisolvent, and composition (solvent/antisolvent volume ratio and three dependent variables (mean particle size, aspect ratio, and roundness were selected. Based on these, a 2–3 mixed-level factorial design was constructed, crystallization was accomplished, and the results were evaluated using Statistica for Windows 13 program. Product assay was performed and it was revealed that improvements in the mean particle size (from ~13 to ~200 µm, roundness (from ~2.4 to ~1.5, aspect ratio (from ~1.7 to ~1.4, and flow properties were observed while polymorphic transitions were avoided.

  1. Optimization of the Critical Parameters of the Spherical Agglomeration Crystallization Method by the Application of the Quality by Design Approach.

    Science.gov (United States)

    Gyulai, Orsolya; Kovács, Anita; Sovány, Tamás; Csóka, Ildikó; Aigner, Zoltán

    2018-04-20

    This research work presents the use of the Quality by Design (QbD) concept for optimization of the spherical agglomeration crystallization method in the case of the active agent, ambroxol hydrochloride (AMB HCl). AMB HCl spherical crystals were formulated by the spherical agglomeration method, which was applied as an antisolvent technique. Spherical crystals have good flowing properties, which makes the direct compression tableting method applicable. This means that the amount of additives used can be reduced and smaller tablets can be formed. For the risk assessment, LeanQbD Software was used. According to its results, four independent variables (mixing type and time, dT (temperature difference between solvent and antisolvent), and composition (solvent/antisolvent volume ratio)) and three dependent variables (mean particle size, aspect ratio, and roundness) were selected. Based on these, a 2⁻3 mixed-level factorial design was constructed, crystallization was accomplished, and the results were evaluated using Statistica for Windows 13 program. Product assay was performed and it was revealed that improvements in the mean particle size (from ~13 to ~200 µm), roundness (from ~2.4 to ~1.5), aspect ratio (from ~1.7 to ~1.4), and flow properties were observed while polymorphic transitions were avoided.

  2. Crystal Growth of High-Quality Protein Crystals under the Presence of an Alternant Electric Field in Pulse-Wave Mode, and a Strong Magnetic Field with Radio Frequency Pulses Characterized by X-ray Diffraction

    Directory of Open Access Journals (Sweden)

    Adela Rodríguez-Romero

    2017-06-01

    Full Text Available The first part of this research was devoted to investigating the effect of alternate current (AC using four different types of wave modes (pulse-wave at 2 Hz on the crystal growth of lysozyme in solution. The best results, in terms of size and crystal quality, were obtained when protein crystals were grown under the influence of electric fields in a very specific wave mode (“breathing” wave, giving the highest resolution up to 1.34 Å in X-ray diffraction analysis compared with controls and with those crystals grown in gel. In the second part, we evaluated the effect of a strong magnetic field of 16.5 Tesla combined with radiofrequency pulses of 0.43 μs on the crystal growth in gels of tetragonal hen egg white (HEW lysozyme. The lysozyme crystals grown, both in solution applying breathing-wave and in gel under the influence of this strong magnetic field with pulses of radio frequencies, produced the larger-in-size crystals and the highest resolution structures. Data processing and refinement statistics are very good in terms of the resolution, mosaicity and Wilson B factor obtained for each crystal. Besides, electron density maps show well-defined and distinctly separated atoms at several selected tryptophan residues for the crystal grown using the “breathing wave pulses”.

  3. Basal-body-associated macromolecules: a continuing debate.

    Science.gov (United States)

    Pierre Mignot, J; Brugerolle, G; Didier, P; Bornens, M

    1993-07-01

    Controversy over the possibility that centrioles/basal bodies contain nucleic acids has overshadowed results demonstrating other macromolecules in the lumen of these organelles. Glycogen particles, which are known to be present within the lumen of the centriole/basal body of sperm cells, have now been found in basal bodies of protists belonging to three different groups. Here, we extend the debate on a role for RNA in basal body/centriole function and speculate on the origin and the function of centriolar glycogen.

  4. Crystal growth of CVD diamond and some of its peculiarities

    CERN Document Server

    Piekarczyk, W

    1999-01-01

    Experiments demonstrate that CVD diamond can form in gas environments that are carbon undersaturated with respect to diamond. This fact is, among others, the most serious violation of principles of chemical thermodynamics. In this $9 paper it is shown that none of the principles is broken when CVD diamond formation is considered not a physical process consisting in growth of crystals but a chemical process consisting in accretion of macro-molecules of polycyclic $9 saturated hydrocarbons belonging to the family of organic compounds the smallest representatives of which are adamantane, diamantane, triamantane and so forth. Since the polymantane macro-molecules are in every respect identical with $9 diamond single crystals with hydrogen-terminated surfaces, the accretion of polymantane macro- molecules is a process completely equivalent to the growth of diamond crystals. However, the accretion of macro-molecules must be $9 described in a way different from that used to describe the growth of crystals because so...

  5. Epitaxial growth of thin single-crystals and their quality study by Rutherford scattering in channeling conditions

    International Nuclear Information System (INIS)

    Kirsch, Robert.

    1975-01-01

    Some aspects of thin crystalline layers are reminded: vacuum deposition, epitaxial growth, annealing and interdiffusion ion channeling and scattering of 1-2MeV helium ions are used to study the crystalline quality, the annealing effects and in some cases the interdiffusion in epitaxial multilayers of silver, copper gold and nickel. Thin single-crystals of gold and nickel oriented (III) plan parallel to the surface were obtained by successive epitaxial growth from muscovite mica clivages. The mounting techniques of single crystalline, self-supporting, 300 to 1200 Angstroems thick, gold and nickel targets of 3mm diameter are described. The gold single-crystals have dislocation densities of 10 8 cm -2 and the various epitaxial layers are obtained without twinning [fr

  6. Development of high quality large laser crystals for a CPA laser system

    International Nuclear Information System (INIS)

    Sugiyama, Akira; Fukuyama, Hiroyasu; Nagai, Shiro; Katsurayama, Masamichi; Anzai, Yutaka

    2000-01-01

    Uniform doped concentration along growth direction of Nd 3+ :YAG crystal with 110 mm length was successfully grown by the Czochralski furnace with a double crucible. The fluctuation of doped concentration was less than 4%, nearly 1/4 of the Nd 3+ :YAG crystal grown by a conventional method. We also demonstrated direct bonding without the use of adhesive materials on Ti:sapphire laser crystals with a bonding surface dimension of 12 mm x 6 mm. The bonding surfaces were treated with chemical processes to clean up and to create a hydrophilic layer for hydrogen bonding in an atmospheric furnace. Successive heat treatment in a vacuum furnace transformed the hydrogen bonding into the direct bonding. From the observation by a transmission electron microscope (Hitachi: HF-2000), atomic level bonding was succeeded in the bonding surface. The performance of the bonded crystal was also tested by laser oscillation with a second harmonics of Q-switched Nd 3+ :YAG at a 20 Hz repetition rate. In comparison with a normal laser crystal, there were no difference in output power or spatial profile in an input condition of 30 mJ. The optical damaged threshold on the bonding surface was estimated over 660 MW/cm 2 . (author)

  7. Copper co-crystallization and divalent metal salts cross-influence effect: A new optimization tool improving crystal morphology and diffraction quality

    Czech Academy of Sciences Publication Activity Database

    Kutá-Smatanová, Ivana

    2007-01-01

    Roč. 306, č. 2 (2007), s. 383-389 ISSN 0022-0248 Institutional research plan: CEZ:AV0Z60870520 Keywords : crystal * crystallization Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.950, year: 2007

  8. A system for the quality inspection of LiNbO3 crystals

    International Nuclear Information System (INIS)

    Smilanski, I.

    1977-12-01

    A prototype system for the characterization of LiNbO 3 crystals by parametric fluorescence was designed and constructed. A specially built metal vapor laser served as a pump and as a calibrator for the system. It was operated both in the He-Cd + mode and in the He-Se + mode. Fluorescence in the 500 nm range, intra-cavity modulation and a correlation detector gave a sensitivity limit of 10 -15 W, and therby enabled the tunning curve and the d 15 of the crystal to be measured. (author)

  9. Quality factor enhancement in photonic crystal slabs by manipulation of the ring of exceptional points

    DEFF Research Database (Denmark)

    Kaminski, Piotr Marek; Taghizadeh, Alireza; Breinbjerg, Olav

    2017-01-01

    Presently, we investigate the influence of the extent of a ring of exceptional points on the Q-factor of three-dimensional photonic crystal slabs. By changing the thickness of the slab, the extent of the ring of exceptional points is varied, allowing us to recover the Dirac cones in open, non......-Hermitian systems. In this case, three bound states in the continuum are exhibited close to the Gamma-point. For an optimized thickness of the slab, the associated Q-factors are found to grow rapidly with the size of the slab. The present results may lead to novel, small area and high Q-factor photonic crystal...

  10. RNA Crystallization

    Science.gov (United States)

    Golden, Barbara L.; Kundrot, Craig E.

    2003-01-01

    RNA molecules may be crystallized using variations of the methods developed for protein crystallography. As the technology has become available to syntheisize and purify RNA molecules in the quantities and with the quality that is required for crystallography, the field of RNA structure has exploded. The first consideration when crystallizing an RNA is the sequence, which may be varied in a rational way to enhance crystallizability or prevent formation of alternate structures. Once a sequence has been designed, the RNA may be synthesized chemically by solid-state synthesis, or it may be produced enzymatically using RNA polymerase and an appropriate DNA template. Purification of milligram quantities of RNA can be accomplished by HPLC or gel electrophoresis. As with proteins, crystallization of RNA is usually accomplished by vapor diffusion techniques. There are several considerations that are either unique to RNA crystallization or more important for RNA crystallization. Techniques for design, synthesis, purification, and crystallization of RNAs will be reviewed here.

  11. Tunable Tensor Voting Improves Grouping of Membrane-Bound Macromolecules

    Energy Technology Data Exchange (ETDEWEB)

    Loss, Leandro A.; Bebis, George; Parvin, Bahram

    2009-04-15

    Membrane-bound macromolecules are responsible for structural support and mediation of cell-cell adhesion in tissues. Quantitative analysis of these macromolecules provides morphological indices for damage or loss of tissue, for example as a result of exogenous stimuli. From an optical point of view, a membrane signal may have nonuniform intensity around the cell boundary, be punctate or diffused, and may even be perceptual at certain locations along the boundary. In this paper, a method for the detection and grouping of punctate, diffuse curvilinear signals is proposed. Our work builds upon the tensor voting and the iterative voting frameworks to propose an efficient method to detect and refine perceptually interesting curvilinear structures in images. The novelty of our method lies on the idea of iteratively tuning the tensor voting fields, which allows the concentration of the votes only over areas of interest. We validate the utility of our system with synthetic and annotated real data. The effectiveness of the tunable tensor voting is demonstrated on complex phenotypic signals that are representative of membrane-bound macromolecular structures.

  12. Physiologically-based PK/PD modelling of therapeutic macromolecules.

    Science.gov (United States)

    Thygesen, Peter; Macheras, Panos; Van Peer, Achiel

    2009-12-01

    Therapeutic proteins are a diverse class of drugs consisting of naturally occurring or modified proteins, and due to their size and physico-chemical properties, they can pose challenges for the pharmacokinetic and pharmacodynamic studies. Physiologically-based pharmacokinetics (PBPK) modelling has been effective for early in silico prediction of pharmacokinetic properties of new drugs. The aim of the present workshop was to discuss the feasibility of PBPK modelling of macromolecules. The classical PBPK approach was discussed with a presentation of the successful example of PBPK modelling of cyclosporine A. PBPK model was performed with transport of the cyclosporine across cell membranes, affinity to plasma proteins and active membrane transporters included to describe drug transport between physiological compartments. For macromolecules, complex PBPK modelling or permeability-limited and/or target-mediated distribution was discussed. It was generally agreed that PBPK modelling was feasible and desirable. The role of the lymphatic system should be considered when absorption after extravascular administration is modelled. Target-mediated drug disposition was regarded as an important feature for generation of PK models. Complex PK-models may not be necessary when a limited number of organs are affected. More mechanistic PK/PD models will be relevant when adverse events/toxicity are included in the PK/PD modelling.

  13. JAIL: a structure-based interface library for macromolecules.

    Science.gov (United States)

    Günther, Stefan; von Eichborn, Joachim; May, Patrick; Preissner, Robert

    2009-01-01

    The increasing number of solved macromolecules provides a solid number of 3D interfaces, if all types of molecular contacts are being considered. JAIL annotates three different kinds of macromolecular interfaces, those between interacting protein domains, interfaces of different protein chains and interfaces between proteins and nucleic acids. This results in a total number of about 184,000 database entries. All the interfaces can easily be identified by a detailed search form or by a hierarchical tree that describes the protein domain architectures classified by the SCOP database. Visual inspection of the interfaces is possible via an interactive protein viewer. Furthermore, large scale analyses are supported by an implemented sequential and by a structural clustering. Similar interfaces as well as non-redundant interfaces can be easily picked out. Additionally, the sequential conservation of binding sites was also included in the database and is retrievable via Jmol. A comprehensive download section allows the composition of representative data sets with user defined parameters. The huge data set in combination with various search options allow a comprehensive view on all interfaces between macromolecules included in the Protein Data Bank (PDB). The download of the data sets supports numerous further investigations in macromolecular recognition. JAIL is publicly available at http://bioinformatics.charite.de/jail.

  14. Structural properties, crystal quality and growth modes of MOCVD-grown AlN with TMAl pretreatment of sapphire substrate

    KAUST Repository

    Sun, Haiding; Wu, Feng; Altahtamouni, Talal Mohammed Ahmad; Alfaraj, Nasir; Li, Kun; Detchprohm, Theeradetch; Dupuis, Russell; Li, Xiaohang

    2017-01-01

    The growth of high quality AlN epitaxial films relies on precise control of the initial growth stages. In this work, we examined the influence of the trimethylaluminum (TMAl) pretreatment of sapphire substrates on the structural properties, crystal quality and growth modes of heteroepitaxial AlN films on (0001) sapphire substrates. Without the pretreatment, the AlN films nucleated on the smooth surface but exhibited mixed crystallographic Al- (N-) polarity, resulting in rough AlN film surfaces. With increasing the pretreatment time from 1 to 5 s, the N-polarity started to be impeded. However, small islands were formed on sapphire surface due to the decompostion of TMAl. As a result, small voids became noticeable at the nucleation layer (NL) because the growth started as quasi three-dimensional (3D) but transformed to 2D mode as the film grew thicker and got coalesced, leading to smoother and Al-polar films. On the other hand, longer pretreatment time of 40 s formed large 3D islands on sapphire, and thus initiated a 3D-growth mode of the AlN film, generating Al-polar AlN nanocolumns with different facets, which resulted into rougher film surfaces. The epitaxial growth modes and their correlation with the AlN film crystal quality under different TMAl pretreatments are also discussed.

  15. Sensitivity of the crystal quality of SiGe layers grown at low temperatures by trisilane and germane

    Energy Technology Data Exchange (ETDEWEB)

    Abedin, A., E-mail: aabedin@kth.se; Moeen, M.; Cappetta, C.; Östling, M.; Radamson, H.H., E-mail: rad@kth.se

    2016-08-31

    This work investigates the crystal quality of SiGe layers grown at low temperatures using trisilane, and germane precursors. The crystal quality sensitivity was monitored for hydrogen chloride and/or minor oxygen amount during SiGe epitaxy or at the interface of SiGe/Si layers. The quality of the epi-layers was examined by quantifying noise parameter, K{sub 1/f} obtained from the power spectral density vs. 1/f curves. The results indicate that while it is difficult to detect small defect densities in SiGe layers by physical material characterization, the noise measurement could reveal the effects of oxygen contamination as low as 0.16 mPa inside and in the interface of the layers. - Highlights: • SiGe layers were grown using trisilane and germane. • Effect of HCl flow on Ge content and growth rate was investigated. • O{sub 2} partial pressures up to 4.3 mPa did not affect x-ray diffraction pattern. • O{sub 2} partial pressures as low as 0.16 mPa increased the noise level. • HCl increased metal contaminations of the layers and the noise level consequently.

  16. Structural properties, crystal quality and growth modes of MOCVD-grown AlN with TMAl pretreatment of sapphire substrate

    KAUST Repository

    Sun, Haiding

    2017-08-08

    The growth of high quality AlN epitaxial films relies on precise control of the initial growth stages. In this work, we examined the influence of the trimethylaluminum (TMAl) pretreatment of sapphire substrates on the structural properties, crystal quality and growth modes of heteroepitaxial AlN films on (0001) sapphire substrates. Without the pretreatment, the AlN films nucleated on the smooth surface but exhibited mixed crystallographic Al- (N-) polarity, resulting in rough AlN film surfaces. With increasing the pretreatment time from 1 to 5 s, the N-polarity started to be impeded. However, small islands were formed on sapphire surface due to the decompostion of TMAl. As a result, small voids became noticeable at the nucleation layer (NL) because the growth started as quasi three-dimensional (3D) but transformed to 2D mode as the film grew thicker and got coalesced, leading to smoother and Al-polar films. On the other hand, longer pretreatment time of 40 s formed large 3D islands on sapphire, and thus initiated a 3D-growth mode of the AlN film, generating Al-polar AlN nanocolumns with different facets, which resulted into rougher film surfaces. The epitaxial growth modes and their correlation with the AlN film crystal quality under different TMAl pretreatments are also discussed.

  17. Terahertz gas sensing based on a simple one-dimensional photonic crystal cavity with high-quality factors

    DEFF Research Database (Denmark)

    Chen, T.; Han, Z. H.; Liu, J. J.

    2014-01-01

    We report in this paper terahertz gas sensing using a simple 1D photonic crystal cavity. The resonant frequencies of the cavity depend linearly on the refractive index of the ambient gas, which can then be measured by monitoring the resonance shift. Although quite easy to manufacture, this cavity...... exhibits high-quality factors, facilitating the realization of high sensitivity in the gas refractive index sensing. In our experiment, 6% of the change of hydrogen concentration in air, which corresponds to a refractive index change of 1.4 x 10(-5), can be steadily detected, and different gas samples can...

  18. Analysis of an industrial production suspension of Bacillus lentus subtilisin crystals by powder diffraction: a powerful quality-control tool.

    Science.gov (United States)

    Frankaer, Christian G; Moroz, Olga V; Turkenburg, Johan P; Aspmo, Stein I; Thymark, Majbritt; Friis, Esben P; Stahl, Kenny; Nielsen, Jens E; Wilson, Keith S; Harris, Pernille

    2014-04-01

    A microcrystalline suspension of Bacillus lentus subtilisin (Savinase) produced during industrial large-scale production was analysed by X-ray powder diffraction (XRPD) and X-ray single-crystal diffraction (MX). XRPD established that the bulk microcrystal sample representative of the entire production suspension corresponded to space group P212121, with unit-cell parameters a = 47.65, b = 62.43, c = 75.74 Å, equivalent to those for a known orthorhombic crystal form (PDB entry 1ndq). MX using synchrotron beamlines at the Diamond Light Source with beam dimensions of 20 × 20 µm was subsequently used to study the largest crystals present in the suspension, with diffraction data being collected from two single crystals (∼20 × 20 × 60 µm) to resolutions of 1.40 and 1.57 Å, respectively. Both structures also belonged to space group P2(1)2(1)2(1), but were quite distinct from the dominant form identified by XRPD, with unit-cell parameters a = 53.04, b = 57.55, c = 71.37 Å and a = 52.72, b = 57.13, c = 65.86 Å, respectively, and refined to R = 10.8% and Rfree = 15.5% and to R = 14.1% and Rfree = 18.0%, respectively. They are also different from any of the forms previously reported in the PDB. A controlled crystallization experiment with a highly purified Savinase sample allowed the growth of single crystals of the form identified by XRPD; their structure was solved and refined to a resolution of 1.17 Å with an R of 9.2% and an Rfree of 11.8%. Thus, there are at least three polymorphs present in the production suspension, albeit with the 1ndq-like microcrystals predominating. It is shown how the two techniques can provide invaluable and complementary information for such a production suspension and it is proposed that XRPD provides an excellent quality-control tool for such suspensions.

  19. Quality of Heusler single crystals examined by depth-dependent positron annihilation techniques

    Science.gov (United States)

    Hugenschmidt, C.; Bauer, A.; Böni, P.; Ceeh, H.; Eijt, S. W. H.; Gigl, T.; Pfleiderer, C.; Piochacz, C.; Neubauer, A.; Reiner, M.; Schut, H.; Weber, J.

    2015-06-01

    Heusler compounds exhibit a wide range of different electronic ground states and are hence expected to be applicable as functional materials in novel electronic and spintronic devices. Since the growth of large and defect-free Heusler crystals is still challenging, single crystals of Fe2TiSn and Cu2MnAl were grown by the optical floating zone technique. Two positron annihilation techniques—angular correlation of annihilation radiation and Doppler broadening spectroscopy (DBS)—were applied in order to study both the electronic structure and lattice defects. Recently, we succeeded to observe clearly the anisotropy of the Fermi surface of Cu2MnAl, whereas the spectra of Fe2TiSn were disturbed by foreign phases. In order to estimate the defect concentration in different samples of Heusler compounds, the positron diffusion length was determined by DBS using a monoenergetic positron beam.

  20. High quality single crystal Ge nano-membranes for opto-electronic integrated circuitry

    International Nuclear Information System (INIS)

    Shah, V. A.; Gammon, P. M.; Rhead, S. D.; Halpin, J. E.; Trushkevych, O.; Wilson, N. R.; Myronov, M.; Edwards, R. S.; Patchett, D. H.; Allred, P. S.; Prest, M. J.; Whall, T. E.; Parker, E. H. C.; Leadley, D. R.; Chávez-Ángel, E.; Shchepetov, A.; Prunnila, M.; Kachkanov, V.; Dolbnya, I. P.; Reparaz, J. S.

    2014-01-01

    A thin, flat, and single crystal germanium membrane would be an ideal platform on which to mount sensors or integrate photonic and electronic devices, using standard silicon processing technology. We present a fabrication technique compatible with integrated-circuit wafer scale processing to produce membranes of thickness between 60 nm and 800 nm, with large areas of up to 3.5 mm 2 . We show how the optical properties change with thickness, including appearance of Fabry-Pérot type interference in thin membranes. The membranes have low Q-factors, which allow the platforms to counteract distortion during agitation and movement. Finally, we report on the physical characteristics showing sub-nm roughness and a homogenous strain profile throughout the freestanding layer, making the single crystal Ge membrane an excellent platform for further epitaxial growth or deposition of materials

  1. High quality single crystal Ge nano-membranes for opto-electronic integrated circuitry

    Energy Technology Data Exchange (ETDEWEB)

    Shah, V. A., E-mail: vishal.shah@warwick.ac.uk; Gammon, P. M. [Department of Engineering, The University of Warwick, Coventry CV4 7AL (United Kingdom); Department of Physics, The University of Warwick, Coventry CV4 7AL (United Kingdom); Rhead, S. D.; Halpin, J. E.; Trushkevych, O.; Wilson, N. R.; Myronov, M.; Edwards, R. S.; Patchett, D. H.; Allred, P. S.; Prest, M. J.; Whall, T. E.; Parker, E. H. C.; Leadley, D. R. [Department of Physics, The University of Warwick, Coventry CV4 7AL (United Kingdom); Chávez-Ángel, E. [ICN2-Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona) (Spain); Department of Physics, UAB, 08193 Bellaterra (Barcelona) (Spain); Shchepetov, A.; Prunnila, M. [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo (Finland); Kachkanov, V.; Dolbnya, I. P. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); Reparaz, J. S. [ICN2-Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona) (Spain); and others

    2014-04-14

    A thin, flat, and single crystal germanium membrane would be an ideal platform on which to mount sensors or integrate photonic and electronic devices, using standard silicon processing technology. We present a fabrication technique compatible with integrated-circuit wafer scale processing to produce membranes of thickness between 60 nm and 800 nm, with large areas of up to 3.5 mm{sup 2}. We show how the optical properties change with thickness, including appearance of Fabry-Pérot type interference in thin membranes. The membranes have low Q-factors, which allow the platforms to counteract distortion during agitation and movement. Finally, we report on the physical characteristics showing sub-nm roughness and a homogenous strain profile throughout the freestanding layer, making the single crystal Ge membrane an excellent platform for further epitaxial growth or deposition of materials.

  2. Quality improvement of CdZnTe single crystal by ultrasound processing

    Science.gov (United States)

    Lisiansky, M.; Berner, A.; Korchnoy, V.

    2017-06-01

    Intrinsic defects and contaminations removal from the undoped p-type Cd0.96Zn0.04Te single crystals has been achieved by the ultrasound vibration processing at the room temperature. Surface analysis based on Auger Electron Spectroscopy, Energy Dispersive Spectroscopy, and Scanning Electron Spectroscopy shows a significant reconstruction of the crystal surface after processing, namely, the appearance of numerous "volcano craters" and triangle-shaped defects with a typical size of 0.2-5.0 μm. Elemental analysis of these defects shows that they are Te inclusions emerged on the surface. The regular crystal surface outside the defects also displays a considerable enrichment by Te. Distinct presence of copper is found in both the thin surface layer and in the defects emerged on the surface. The surface reconstruction is associated with a remarkable change in the bulk material properties, electrical (an increase in the resistivity by a factor of ∼6) and optical (an IR transmittance increase). A post-polishing following the ultrasound processing makes the CdZnTe material more stable and reliable for a wide range of device applications.

  3. Long charged macromolecule in an entropic trap with rough surfaces.

    Science.gov (United States)

    Mamasakhlisov, Yevgeni Sh; Hayryan, Shura; Hu, Chin-Kun

    2012-11-01

    The kinetics of the flux of a charged macromolecular solution through an environment of changing geometry with wide and constricted regions is investigated analytically. A model device consisting of alternating deep and shallow slits known as an "entropic trap" is used to represent the environment. The flux is supported by the external electrostatic field. The "wormlike chain" model is used for the macromolecule (dsDNA in the present study). The chain entropy in both the deep and the shallow slits, the work by the electric field, and the energy of the elastic bending of the chain are taken into account accurately. Based on the calculated free energy, the kinetics and the scaling behavior of the chain escaping from the entropic trap are studied. We find that the escape process occurs in two kinetic stages with different time scales and discuss the possible influence of the surface roughness. The scope of the accuracy of the proposed model is discussed.

  4. Macromolecule exchange in Cuscuta-host plant interactions.

    Science.gov (United States)

    Kim, Gunjune; Westwood, James H

    2015-08-01

    Cuscuta species (dodders) are parasitic plants that are able to grow on many different host plants and can be destructive to crops. The connections between Cuscuta and its hosts allow movement of not only water and small nutrients, but also macromolecules including mRNA, proteins and viruses. Recent studies show that RNAs move bidirectionally between hosts and parasites and involve a large number of different genes. Although the function of mobile mRNAs has not been demonstrated in this system, small RNAs are also transmitted and a silencing construct expressed in hosts is able to affect expression of the target gene in the parasite. High throughput sequencing of host-parasite associations has the potential to greatly accelerate understanding of this remarkable interaction. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Medial frontal GABA is lower in older schizophrenia: a MEGA-PRESS with macromolecule suppression study.

    Science.gov (United States)

    Rowland, L M; Krause, B W; Wijtenburg, S A; McMahon, R P; Chiappelli, J; Nugent, K L; Nisonger, S J; Korenic, S A; Kochunov, P; Hong, L E

    2016-02-01

    Gamma-butyric acid (GABA) dysfunction has been implicated in the pathophysiology of schizophrenia and its cognitive deficits. Proton magnetic resonance spectroscopy (MRS) was used to test the hypothesis that older participants with schizophrenia have lower anterior cingulate GABA levels compared with older control participants. One-hundred forty-five participants completed this study. For detection of GABA, spectra were acquired from the medial frontal/anterior cingulate cortex using a macromolecule-suppressed MEGA-PRESS sequence. Patients were evaluated for psychopathology and all participants completed neuropsychological tests of working memory, processing speed and functional capacity. GABA levels were significantly lower in the older participants with schizophrenia (n=31) compared with the older control (n=37) group (P=0.003) but not between the younger control (n=40) and schizophrenia (n=29) groups (P=0.994). Age strongly predicted GABA levels in the schizophrenia group accounting for 42% of the variance, but the effect of age was less in the control group accounting for 5.7% of the variance. GABA levels were specifically related to working memory but not processing speed performance, functional capacity, or positive or negative symptom severity. This is the largest MRS study of GABA in schizophrenia and the first to examine GABA without macromolecule contamination, a potentially significant issue in previous studies. GABA levels more rapidly declined with advancing age in the schizophrenia compared with the control group. Interventions targeted at halting the decline or increasing GABA levels may improve functional outcomes and quality of life as patients with schizophrenia age.

  6. General crystal in prebiotic context

    International Nuclear Information System (INIS)

    Simon, I.

    1993-09-01

    General crystal is an extension of the crystal concept to any form of matter which exhibit neighbour structure determination. This extension makes many results of solid state physics applicable to heterogeneous matter. Among other it includes the description of phase transition from random to unique structure. The advantage of the general crystal approach is demonstrated on globular protein, on of the most important macromolecules of life, which are capable to adopt unique 3D structure spontaneously, regardless of the heterogeneous character of their chemical structure and conformation. It is suggested that the use of general crystal concept may help to find candidates among heterogeneous matters capable to spontaneous self-organization in the same way as crystallization results in unique structure of homogeneous matter, and to apply some of the results of solid state physics to describe the phase transition and other behaviour of this matter. (author). 10 refs

  7. Highly Resolved Sub-Terahertz Vibrational Spectroscopy of Biological Macromolecules and Bacteria Cells

    Science.gov (United States)

    2016-07-01

    HIGHLY RESOLVED SUB-TERAHERTZ VIBRATIONAL SPECTROSCOPY OF BIOLOGICAL MACROMOLECULES AND BACTERIA CELLS ECBC...SUBTITLE Highly Resolved Sub-Terahertz Vibrational Spectroscopy of Biological Macromolecules and Bacteria Cells 5a. CONTRACT NUMBER W911SR-14-P...22 4.3 Bacteria THz Study

  8. Macromolecule biosynthesis assay and fluorescence spectroscopy methods to explore antimicrobial peptide mode(s) of action

    DEFF Research Database (Denmark)

    Jana, Bimal; Baker, Kristin Renee; Guardabassi, Luca

    2017-01-01

    the biosynthesis rate of macromolecules (e.g., DNA, RNA, protein, and cell wall) and the cytoplasmic membrane proton motive force (PMF) energy can help to unravel the diverse modes of action of AMPs. Here, we present an overview of macromolecule biosynthesis rate measurement and fluorescence spectroscopy methods...

  9. The flavonoid herbacetin diglucoside as a constituent of the lignan macromolecule from flaxseed hulls

    NARCIS (Netherlands)

    Struijs, K.; Vincken, J.P.; Verhoef, R.P.; Oostveen, van W.H.M.; Voragen, A.G.J.; Gruppen, H.

    2007-01-01

    Lignans in flaxseed are known to be part of a macromolecule in which they are connected through the linker-molecule hydroxy-methyl-glutaric acid (HMGA). In this study, the lignan macromolecule was extracted from flaxseed hulls and degraded to its monomeric constituents by complete saponification.

  10. Defined PEG smears as an alternative approach to enhance the search for crystallization conditions and crystal-quality improvement in reduced screens

    Energy Technology Data Exchange (ETDEWEB)

    Chaikuad, Apirat, E-mail: apirat.chaikuad@sgc.ox.ac.uk [University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Headington, Oxford OX3 7DQ (United Kingdom); Knapp, Stefan [University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Headington, Oxford OX3 7DQ (United Kingdom); Johann Wolfgang Goethe-University, Building N240 Room 3.03, Max-von-Laue-Strasse 9, 60438 Frankfurt am Main (Germany); Delft, Frank von, E-mail: apirat.chaikuad@sgc.ox.ac.uk [University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Headington, Oxford OX3 7DQ (United Kingdom)

    2015-07-28

    An alternative strategy for PEG sampling is suggested through the use of four newly defined PEG smears to enhance chemical space in reduced screens with a benefit towards protein crystallization. The quest for an optimal limited set of effective crystallization conditions remains a challenge in macromolecular crystallography, an issue that is complicated by the large number of chemicals which have been deemed to be suitable for promoting crystal growth. The lack of rational approaches towards the selection of successful chemical space and representative combinations has led to significant overlapping conditions, which are currently present in a multitude of commercially available crystallization screens. Here, an alternative approach to the sampling of widely used PEG precipitants is suggested through the use of PEG smears, which are mixtures of different PEGs with a requirement of either neutral or cooperatively positive effects of each component on crystal growth. Four newly defined smears were classified by molecular-weight groups and enabled the preservation of specific properties related to different polymer sizes. These smears not only allowed a wide coverage of properties of these polymers, but also reduced PEG variables, enabling greater sampling of other parameters such as buffers and additives. The efficiency of the smear-based screens was evaluated on more than 220 diverse recombinant human proteins, which overall revealed a good initial crystallization success rate of nearly 50%. In addition, in several cases successful crystallizations were only obtained using PEG smears, while various commercial screens failed to yield crystals. The defined smears therefore offer an alternative approach towards PEG sampling, which will benefit the design of crystallization screens sampling a wide chemical space of this key precipitant.

  11. Influence of in-situ deposited SiNx interlayer on crystal quality of GaN epitaxial films

    Science.gov (United States)

    Fan, Teng; Jia, Wei; Tong, Guangyun; Zhai, Guangmei; Li, Tianbao; Dong, Hailiang; Xu, Bingshe

    2018-05-01

    GaN epitaxial films with SiNx interlayers were prepared by metal organic chemical vapor deposition (MOCVD) on c-plane sapphire substrates. The influences of deposition times and locations of SiNx interlayers on crystal quality of GaN epitaxial films were studied. Under the optimal growth time of 120 s for the SiNx interlayer, the dislocation density of GaN film is reduced to 4.05 × 108 cm-2 proved by high resolution X-ray diffraction results. It is found that when the SiNx interlayer deposits on the GaN nucleation islands, the subsequent GaN film has the lowest dislocation density of only 2.89 × 108 cm-2. Moreover, a model is proposed to illustrate the morphological evolution and associated propagation processes of TDs in GaN epi-layers with SiNx interlayers for different deposition times and locations.

  12. Nanostructure-Enabled and Macromolecule-Grafted Surfaces for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Madeline Small

    2018-05-01

    Full Text Available Advances in nanotechnology and nanomaterials have enabled the development of functional biomaterials with surface properties that reduce the rate of the device rejection in injectable and implantable biomaterials. In addition, the surface of biomaterials can be functionalized with macromolecules for stimuli-responsive purposes to improve the efficacy and effectiveness in drug release applications. Furthermore, macromolecule-grafted surfaces exhibit a hierarchical nanostructure that mimics nanotextured surfaces for the promotion of cellular responses in tissue engineering. Owing to these unique properties, this review focuses on the grafting of macromolecules on the surfaces of various biomaterials (e.g., films, fibers, hydrogels, and etc. to create nanostructure-enabled and macromolecule-grafted surfaces for biomedical applications, such as thrombosis prevention and wound healing. The macromolecule-modified surfaces can be treated as a functional device that either passively inhibits adverse effects from injectable and implantable devices or actively delivers biological agents that are locally based on proper stimulation. In this review, several methods are discussed to enable the surface of biomaterials to be used for further grafting of macromolecules. In addition, we review surface-modified films (coatings and fibers with respect to several biomedical applications. Our review provides a scientific update on the current achievements and future trends of nanostructure-enabled and macromolecule-grafted surfaces in biomedical applications.

  13. Improved data visualization techniques for analyzing macromolecule structural changes.

    Science.gov (United States)

    Kim, Jae Hyun; Iyer, Vidyashankara; Joshi, Sangeeta B; Volkin, David B; Middaugh, C Russell

    2012-10-01

    The empirical phase diagram (EPD) is a colored representation of overall structural integrity and conformational stability of macromolecules in response to various environmental perturbations. Numerous proteins and macromolecular complexes have been analyzed by EPDs to summarize results from large data sets from multiple biophysical techniques. The current EPD method suffers from a number of deficiencies including lack of a meaningful relationship between color and actual molecular features, difficulties in identifying contributions from individual techniques, and a limited ability to be interpreted by color-blind individuals. In this work, three improved data visualization approaches are proposed as techniques complementary to the EPD. The secondary, tertiary, and quaternary structural changes of multiple proteins as a function of environmental stress were first measured using circular dichroism, intrinsic fluorescence spectroscopy, and static light scattering, respectively. Data sets were then visualized as (1) RGB colors using three-index EPDs, (2) equiangular polygons using radar charts, and (3) human facial features using Chernoff face diagrams. Data as a function of temperature and pH for bovine serum albumin, aldolase, and chymotrypsin as well as candidate protein vaccine antigens including a serine threonine kinase protein (SP1732) and surface antigen A (SP1650) from S. pneumoniae and hemagglutinin from an H1N1 influenza virus are used to illustrate the advantages and disadvantages of each type of data visualization technique. Copyright © 2012 The Protein Society.

  14. Molecular simulation of methane adsorption characteristics on coal macromolecule

    Science.gov (United States)

    Yang, Zhiyuan; He, Xiaoxiao; Meng, Zhuoyue; Xue, Wenying

    2018-02-01

    In this paper, the molecular model of anthracite named Wender2 was selected to study the adsorption behaviour of single component CH4 and the competitive adsorption of CH4/CO2, CH4/H2O and CH4/N2. The molecular model of anthracite was established by molecular simulation software (Materials Studio 8.0), and Grand Canonical Monte Carlo (GCMC) simulations were carried out to investigate the single and binary component adsorption. The effects of pressure and temperature on the adsorption position, adsorption energy and adsorption capacity were mainly discussed. The results show that for the single component adsorption, the adsorption capacity of CH4 increases rapidly with the pressure ascending, and then tends to be stable after the first step. The low temperature is favourable for the adsorption of CH4, and the high temperature promotes desorption quantity of CH4 from the coal. Adsorbent molecules are preferentially adsorbed on the edge of coal macromolecules. The order of adsorption capacity of CH4/CO2, CH4/H2O and CH4/N2 in the binary component is H2O>CO2>CH4>N2. The change of pressure has little effect on the adsorption capacity of the adsorbent in the competitive adsorption, but it has a great influence on the adsorption capacity of the adsorbent, and there is a positive correlation between them.

  15. N-hydroxysuccinimide-hippuran ester: application for radiolabeling of macromolecules

    International Nuclear Information System (INIS)

    Chervu, L.R.; Chun, S.B.; Bhargava, K.K.

    1987-01-01

    A method for synthesis of N-hydroxysuccinimide ester of radioactive orthoiodohippurric acid (OIH-OSU) is developed in order to label macromolecules including antibodies. The OIH-OSU is prepared in 87% yield by reacting molar equivalents of o-iodohippuric acid, N:N-di-succinimidyl carbonate and pyridine in DMF overnight. The active labeled ester is obtained using high specific activity OIH in a similar synthetic protocol. Conjugation of OIH-OSU to human serum albumin is effected by incubating the reactants for half an hour at room temperature followed by purification of the labeled protein on a Sephadex G-100 column with activity yield of 44.3%. Organ distribution for the labeled albumin preparation and the commercial iodinated human serum albumin (RISA) in mice and rats is similar. As expected urinary excretion of radioactivity for the labeled preparation is greater than that of RISA reflecting the rapid urinary clearance of the OIH moiety released into the bloodstream. Hippuran labeling method offers a mild and rapid protocol for radioiodine labeling of proteins and antibodies for application in diagnostic nuclear medicine procedures

  16. Interaction between manufactured gold nanoparticles and naturally occurring organic macromolecules

    International Nuclear Information System (INIS)

    Diegoli, Sara; Manciulea, Adriana L.; Begum, Shakiela; Jones, Ian P.; Lead, Jamie R.; Preece, Jon A.

    2008-01-01

    The increasing exploitation of nanomaterials into many consumer and other products is raising concerns as these nanomaterials are likely to be released into the environment. Due to our lack of knowledge about the environmental chemistry, transport and ecotoxicology of nanomaterials, it is of paramount importance to study how natural aquatic colloids can interact with manufactured gold nanoparticles as these interactions will determine their environmental fate and behaviour. In this context, our work aims to quantify the effect of naturally occurring riverine macromolecules - International Humic Substances Society (IHSS) Suwannee River Humic Acid Standard (SRHA) - on citrate- and acrylate-stabilized gold nanoparticles. The influence of SRHA on the stability of the gold colloids was studied as a function of pH by UV-visible absorption spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM). At high ionic strengths (0.1 M), extensive and rapid aggregation occurred, while more subtle effects were observed at lower ionic strength values. Evidence was found that SRHA enhances particle stability at extreme pH values (ionic strength < 0.01 M) by substituting and/or over-coating the original stabilizer on the gold nanoparticle surface, thus affecting surface charge and chemistry. These findings have important implications for the fate and behaviour of nanoparticles in the environment and their ecotoxicity

  17. Traceable atomic force microscopy of high-quality solvent-free crystals of [6,6]-phenyl-C61-butyric acid methyl ester

    International Nuclear Information System (INIS)

    Lazzerini, Giovanni Mattia; Yacoot, Andrew; Paternò, Giuseppe Maria; Tregnago, Giulia; Cacialli, Franco; Treat, Neil; Stingelin, Natalie

    2016-01-01

    We report high-resolution, traceable atomic force microscopy measurements of high-quality, solvent-free single crystals of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). These were grown by drop-casting PCBM solutions onto the spectrosil substrates and by removing the residual solvent in a vacuum. A home-built atomic force microscope featuring a plane mirror differential optical interferometer, fiber-fed from a frequency-stabilized laser (emitting at 632.8 nm), was used to measure the crystals' height. The optical interferometer together with the stabilized laser provides traceability (via the laser wavelength) of the vertical measurements made with the atomic force microscope. We find that the crystals can conform to the surface topography, thanks to their height being significantly smaller compared to their lateral dimensions (namely, heights between about 50 nm and 140 nm, for the crystals analysed, vs. several tens of microns lateral dimensions). The vast majority of the crystals are flat, but an isolated, non-flat crystal provides insights into the growth mechanism and allows identification of “molecular terraces” whose height corresponds to one of the lattice constants of the single PCBM crystal (1.4 nm) as measured with X-ray diffraction

  18. Traceable atomic force microscopy of high-quality solvent-free crystals of [6,6]-phenyl-C61-butyric acid methyl ester

    Science.gov (United States)

    Lazzerini, Giovanni Mattia; Paternò, Giuseppe Maria; Tregnago, Giulia; Treat, Neil; Stingelin, Natalie; Yacoot, Andrew; Cacialli, Franco

    2016-02-01

    We report high-resolution, traceable atomic force microscopy measurements of high-quality, solvent-free single crystals of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). These were grown by drop-casting PCBM solutions onto the spectrosil substrates and by removing the residual solvent in a vacuum. A home-built atomic force microscope featuring a plane mirror differential optical interferometer, fiber-fed from a frequency-stabilized laser (emitting at 632.8 nm), was used to measure the crystals' height. The optical interferometer together with the stabilized laser provides traceability (via the laser wavelength) of the vertical measurements made with the atomic force microscope. We find that the crystals can conform to the surface topography, thanks to their height being significantly smaller compared to their lateral dimensions (namely, heights between about 50 nm and 140 nm, for the crystals analysed, vs. several tens of microns lateral dimensions). The vast majority of the crystals are flat, but an isolated, non-flat crystal provides insights into the growth mechanism and allows identification of "molecular terraces" whose height corresponds to one of the lattice constants of the single PCBM crystal (1.4 nm) as measured with X-ray diffraction.

  19. Traceable atomic force microscopy of high-quality solvent-free crystals of [6,6]-phenyl-C{sub 61}-butyric acid methyl ester

    Energy Technology Data Exchange (ETDEWEB)

    Lazzerini, Giovanni Mattia; Yacoot, Andrew [National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW (United Kingdom); Paternò, Giuseppe Maria; Tregnago, Giulia; Cacialli, Franco [Department of Physics and Astronomy and London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT (United Kingdom); Treat, Neil; Stingelin, Natalie [Department of Materials Science, Imperial College London, London SW7 2AZ (United Kingdom)

    2016-02-01

    We report high-resolution, traceable atomic force microscopy measurements of high-quality, solvent-free single crystals of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). These were grown by drop-casting PCBM solutions onto the spectrosil substrates and by removing the residual solvent in a vacuum. A home-built atomic force microscope featuring a plane mirror differential optical interferometer, fiber-fed from a frequency-stabilized laser (emitting at 632.8 nm), was used to measure the crystals' height. The optical interferometer together with the stabilized laser provides traceability (via the laser wavelength) of the vertical measurements made with the atomic force microscope. We find that the crystals can conform to the surface topography, thanks to their height being significantly smaller compared to their lateral dimensions (namely, heights between about 50 nm and 140 nm, for the crystals analysed, vs. several tens of microns lateral dimensions). The vast majority of the crystals are flat, but an isolated, non-flat crystal provides insights into the growth mechanism and allows identification of “molecular terraces” whose height corresponds to one of the lattice constants of the single PCBM crystal (1.4 nm) as measured with X-ray diffraction.

  20. 5,5'-Dithio-bis(2-nitrobenzoic acid) modification of cysteine improves the crystal quality of human chloride intracellular channel protein 2

    International Nuclear Information System (INIS)

    Mi Wei; Li Lanfen; Su Xiaodong

    2008-01-01

    Structural studies of human chloride intracellular channel protein 2 (CLIC2) had been hampered by the problem of generating suitable crystals primarily due to the protein containing exposed cysteines. Several chemical reagents were used to react with the cysteines on CLIC2 in order to modify the redox state of the protein. We have obtained high quality crystals that diffracted to better than 2.5 A at a home X-ray source by treating the protein with 5,5'-dithio-bis(2-nitrobenzoic acid) (DTNB). After solving the crystal structure of CLIC2, we found that the DTNB had reacted with the Cys 114 , and made CLIC2 in a homogenous oxidized state. This study demonstrated that the DTNB modification drastically improved the crystallization of CLIC2, and it implied that this method may be useful for other proteins containing exposed cysteines in general

  1. Intramolecular Charge Transfer of Conjugated Liquid Crystal Ferrocene Macromolecules - Synthesis and Characterization

    Science.gov (United States)

    2016-04-12

    Bello 2800 Santiago, Chile 10. SPONSOR/MONITOR’S ACRONYM(S) AFRL/AFOSR IOS 11. SPONSOR/MONITOR’S REPORT NUMBER(S) AFRL-AFOSR-CL-TR-2016-0012   12...properties are of interest because polarized light emitters or light absorption devices, such as OLEDS, solar cells or wave guides, filters and Faraday...DSC) analyses were carried out on a DuPont 951 instrument under nitrogen at a heating rate of 10 °C/min. Small and wide angle X ray scattering

  2. Anomalous magnetotransport properties of high-quality single crystals of Weyl semimetal WTe2: Sign change of Hall resistivity

    Science.gov (United States)

    Jha, Rajveer; Higashinaka, Ryuji; Matsuda, Tatsuma D.; Ribeiro, Raquel A.; Aoki, Yuji

    2018-05-01

    We report on a systematic study of Hall effect using high quality single crystals of type-II Weyl semimetal WTe2 with the applied magnetic field B//c. The residual resistivity ratio of 1330 and the large magnetoresistance of 1.5 × 106 % in 9 T at 2 K, being in the highest class in the literature, attest to their high quality. Based on a simple two-carrier model, the densities (ne and nh) and mobilities (μe and μh) for electron and hole carriers have been uniquely determined combining both Hall- and electrical-resistivity data. The difference between ne and nh is 1% at 2 K, indicating that the system is in an compensated condition. The negative Hall resistivity growing rapidly below 20 K is due to a rapidly increasing μh/μe approaching one. Below 3 K in a low field region, we found the Hall resistivity becomes positive, reflecting that μh/μe finally exceeds one in this region. These anomalous behaviors of the carrier densities and mobilities might be associated with the existence of a Lifshitz transition and/or the spin texture on the Fermi surface.

  3. Control of Process Operations and Monitoring of Product Qualities through Generic Model-based Framework in Crystallization Processes

    DEFF Research Database (Denmark)

    Abdul Samad, Noor Asma Fazli Bin

    A generic and systematic model-based framework for the design of a process monitoring and control system to achieve the desired crystal size distribution (CSD) and crystal shape for a wide range of crystallization processes has been developed. This framework combines a generic multi-dimensional m...

  4. In vivo skin penetration of macromolecules in irritant contact dermatitis.

    Science.gov (United States)

    Abdel-Mottaleb, Mona M A; Lamprecht, Alf

    2016-12-30

    Recently, a selective preferential accumulation of polymeric nanoparticles (in the size range around 100nm) has been observed in the follicular system of dermatitis skin. The present investigation aimed at clearly investigating the effect of irritant contact dermatitis on the barrier permeability for colloidal systems below this size range, namely quantum dots and hydrophilic macromolecules. Irritant dermatitis was induced in mice and the penetrability of quantum dots (5nm) and hydrophilic dextran molecules has been tracked in both healthy and inflamed skin using confocal laser scanning microscopy. The selective accumulation of the quantum dots was clearly observed in inflamed skin while hydrophilic dextran behaved similarly in both healthy and inflamed skin. The therapeutic potential for the transdermal delivery of peptide drugs through inflamed skin has been also tested in rats. Results revealed that the transdermal permeation of insulin and calcitonin was not significantly enhanced in dermatitis compared to healthy skin. On the other side, permeation through stripped skin was significantly higher. However, the effect was limited and shorter compared to the SC injection where t min was 0.5h and 2h with a 70% and 46% reduction in blood glucose levels for the stripped skin and the SC injection respectively. Similarly, t min was 4h and 8h with area under the curve of 161±65% and 350±97% for the stripped skin and the SC injection respectively. In conclusion, the changes in skin permeability accompanied with skin inflammation did not affect its permeability to peptide drugs. Our findings also underline that experiments with the tape stripped skin model as a surrogate for inflamed skin can risk misleading conclusions due to significant difference of skin permeability between the tape stripped skin and inflamed skin. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Sub-terahertz resonance spectroscopy of biological macromolecules and cells

    Science.gov (United States)

    Globus, Tatiana; Moyer, Aaron; Gelmont, Boris; Khromova, Tatyana; Sizov, Igor; Ferrance, Jerome

    2013-05-01

    Recently we introduced a Sub-THz spectroscopic system for characterizing vibrational resonance features from biological materials. This new, continuous-wave, frequency-domain spectroscopic sensor operates at room temperature between 315 and 480 GHz with spectral resolution of at least 1 GHz and utilizes the source and detector components from Virginia Diode, Inc. In this work we present experimental results and interpretation of spectroscopic signatures from bacterial cells and their biological macromolecule structural components. Transmission and absorption spectra of the bacterial protein thioredoxin, DNA and lyophilized cells of Escherichia coli (E. coli), as well as spores of Bacillus subtillis and B. atrophaeus have been characterized. Experimental results for biomolecules are compared with absorption spectra calculated using molecular dynamics simulation, and confirm the underlying physics for resonance spectroscopy based on interactions between THz radiation and vibrational modes or groups of modes of atomic motions. Such interactions result in multiple intense and narrow specific resonances in transmission/absorption spectra from nano-gram samples with spectral line widths as small as 3 GHz. The results of this study indicate diverse relaxation dynamic mechanisms relevant to sub-THz vibrational spectroscopy, including long-lasting processes. We demonstrate that high sensitivity in resolved specific absorption fingerprints provides conditions for reliable detection, identification and discrimination capability, to the level of strains of the same bacteria, and for monitoring interactions between biomaterials and reagents in near real-time. Additionally, it creates the basis for the development of new types of advanced biological sensors through integrating the developed system with a microfluidic platform for biomaterial samples.

  6. High throughput screening of ligand binding to macromolecules using high resolution powder diffraction

    Science.gov (United States)

    Von Dreele, Robert B.; D'Amico, Kevin

    2006-10-31

    A process is provided for the high throughput screening of binding of ligands to macromolecules using high resolution powder diffraction data including producing a first sample slurry of a selected polycrystalline macromolecule material and a solvent, producing a second sample slurry of a selected polycrystalline macromolecule material, one or more ligands and the solvent, obtaining a high resolution powder diffraction pattern on each of said first sample slurry and the second sample slurry, and, comparing the high resolution powder diffraction pattern of the first sample slurry and the high resolution powder diffraction pattern of the second sample slurry whereby a difference in the high resolution powder diffraction patterns of the first sample slurry and the second sample slurry provides a positive indication for the formation of a complex between the selected polycrystalline macromolecule material and at least one of the one or more ligands.

  7. Modelisation of the concentration of macromolecules moving in a Newtonian fluid

    International Nuclear Information System (INIS)

    Hijazi, A.; Zoaeter, M.; Khater, A.; Aussere, D.

    1998-01-01

    Author.This article presents a modelisation of the distribution of a diluted solution of macromolecules submitted to a simple flow in the neighborhood of a non-absorbing solid surface. These macromolecules (length L, negligible diameter) are submitted to two kinds of forces: rotational and translational with brownian and hydrodynamic origins. The evolution of orientation of these molecules in terms of time has been studied, given Einstein equation =D with D coefficient of translation and rotation. By taking as parameters the orientation θ of the macromolecules with respect to an horizontal axis and Z the distance between these macromolecules and the surface, a statistical study has led to determine the distribution. For that reason, the brownian movement considered is supposed to follow a rule of random probability

  8. Equilibrium partitioning of macromolecules in confining geometries: Improved universality with a new molecular size parameter

    DEFF Research Database (Denmark)

    Wang, Yanwei; Peters, Günther H.J.; Hansen, Flemming Yssing

    2008-01-01

    structures (CABS), allows the computation of equilibrium partition coefficients as a function of confinement size solely based on a single sampling of the configuration space of a macromolecule in bulk. Superior in computational speed to previous computational methods, CABS is capable of handling slits...... parameter for characterization of spatial confinement effects on macromolecules. Results for the equilibrium partition coefficient in the weak confinement regime depend only on the ratio ofR-s to the confinement size regardless of molecular details....

  9. Single molecule optical measurements of orientation and rotations of biological macromolecules

    OpenAIRE

    Shroder, Deborah Y; Lippert, Lisa G; Goldman, Yale E

    2016-01-01

    The subdomains of macromolecules often undergo large orientation changes during their catalytic cycles that are essential for their activity. Tracking these rearrangements in real time opens a powerful window into the link between protein structure and functional output. Site-specific labeling of individual molecules with polarized optical probes and measuring their spatial orientation can give insight into the crucial conformational changes, dynamics, and fluctuations of macromolecules. Here...

  10. Universal aspects of macromolecules in polymer blends, solutions, and supercritical mixtures

    International Nuclear Information System (INIS)

    Melnichenko, Y.B.; Wignall, G.D.; Schwahn, D.

    2002-01-01

    We demonstrate that macromolecules in miscible polymer blends may behave as good, Θ, and poor polymeric solvents for each other. We construct a conceptual phase diagram, delineating the range of validity of the random-phase approximation, outside of which polymers contract or expand beyond their unperturbed dimensions, contrary to common assumptions. Remarkably, the correlation length for polymer blends, solutions, and supercritical mixtures collapses onto a master curve, reflecting universal behavior for macromolecules in polymeric and small-molecule Θ solvents

  11. A simple model for electrical charge in globular macromolecules and linear polyelectrolytes in solution

    Science.gov (United States)

    Krishnan, M.

    2017-05-01

    We present a model for calculating the net and effective electrical charge of globular macromolecules and linear polyelectrolytes such as proteins and DNA, given the concentration of monovalent salt and pH in solution. The calculation is based on a numerical solution of the non-linear Poisson-Boltzmann equation using a finite element discretized continuum approach. The model simultaneously addresses the phenomena of charge regulation and renormalization, both of which underpin the electrostatics of biomolecules in solution. We show that while charge regulation addresses the true electrical charge of a molecule arising from the acid-base equilibria of its ionizable groups, charge renormalization finds relevance in the context of a molecule's interaction with another charged entity. Writing this electrostatic interaction free energy in terms of a local electrical potential, we obtain an "interaction charge" for the molecule which we demonstrate agrees closely with the "effective charge" discussed in charge renormalization and counterion-condensation theories. The predictions of this model agree well with direct high-precision measurements of effective electrical charge of polyelectrolytes such as nucleic acids and disordered proteins in solution, without tunable parameters. Including the effective interior dielectric constant for compactly folded molecules as a tunable parameter, the model captures measurements of effective charge as well as published trends of pKa shifts in globular proteins. Our results suggest a straightforward general framework to model electrostatics in biomolecules in solution. In offering a platform that directly links theory and experiment, these calculations could foster a systematic understanding of the interrelationship between molecular 3D structure and conformation, electrical charge and electrostatic interactions in solution. The model could find particular relevance in situations where molecular crystal structures are not available or

  12. An investigation of the shedding of macromolecules from the Ehrlich mouse ascites tumor cell

    International Nuclear Information System (INIS)

    Edwards, E.H.

    1984-01-01

    The spontaneous release, or shedding, of cell surface components into the extracellular medium may be important in the determination of several features of the cancer cell phenotype. The release of macromolecules from the Erhlich mouse ascites tumor cell was studied under a variety of experimental conditions to elucidate the origin and the underlying mechanisms of release. The extrinsic macromolecules are a diverse group with apparent molecular weights ranging from 13,500 to 400,000 daltons. External labeling of the cell surface with tritiated 4,4'-diisothiocyano-1,2-diphenylethane-2,2-disulfonic acid ([ 3 H]H 2 DIDS) reveals a slow loss of labeled components at 4 degrees C, while at 21 degrees C and 37 degrees C an initial rapid loss is followed by a slower release. In vitro metabolic labeling with [1- 14 C]-D-glucosamine hydrochloride, D-[2- 3 H]-mannose and various [ 3 H]-L-amino acids results in the appearance of labeled macromolecules in the medium suggesting tumor, not mouse, origin. These data suggest that the extrinsic macromolecules originate from the cell surface. Macromolecules are shed by a temperature and pH sensitive process. These results suggest that a limited proteolytic digestion, or sublethal autolysis, of the cell surface may occur in this system. The macromolecules shed by the Ehrlich cell originate from the surface and are probably released by sublethal autolysis, direct secretion and a passive process

  13. Imaging Macromolecules with X-ray laser pulses

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    The short wavelength of X-rays allows us to resolve atoms, but in practise for biological materials the achievable resolution is limited by the destruction of the sample by the radiation that forms the image.  For over 100 years, the workaround to this problem of radiation damage has been to average signals from repeating copies of the object arranged in a large crystal.  It is now possible to overcome damage limits by using intense X-ray pulses that vaporise the sample, but which are short enough in duration to freeze any motion of the sample on the atomic scale.  With the advent of X-ray FELs we have been able to confirm this principle, and are now applying it to overcoming a major bottleneck for protein crystallography, which is the need for large well-diffracting crystals.  The intense pulses also open up opportunities to help solve the crystallographic phase problem.  In particular we have found that commonly-occurring disordered crystals that are usually not ...

  14. The effect of a slight mis-orientation angle of c-plane sapphire substrate on surface and crystal quality of MOCVD grown GaN thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seong-Woo; Suzuki, Toshimasa [Nippon Institute of Technology, 4-1 Gakuendai, Miyashiro, Saitama, 345-8501 (Japan); Aida, Hideo [NAMIKI Precision Jewel Co. Ltd., 3-8-22 Shinden, Adachi-ku, Tokyo, 123-8511 (Japan)

    2004-09-01

    The effect of a slight mis-orientation of c-plane sapphire substrate on the surface morphology and crystal quality of GaN thin films grown by MOCVD has been investigated. The mis-orientation angle of vicinal c-plane sapphire substrate was changed within the range of 0.00(zero)-1.00(one) degree, and the experimental results were compared with those on just angle (zero degree) c-plane sapphire substrate. The surface morphology and crystal quality were found to be very sensitive to mis-orientation angle. Consequently, the mis-orientation angle was optimized to be 0.15 . (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Crystallization and Characterization of Galdieria sulphuraria RUBISCO in Two Crystal Forms: Structural Phase Transition Observed in P21 Crystal Form

    Directory of Open Access Journals (Sweden)

    Boguslaw Stec

    2007-10-01

    Full Text Available We have isolated ribulose-1,5-bisphosphate-carboxylase/oxygenase (RUBISCOfrom the red algae Galdieria Sulphuraria. The protein crystallized in two different crystalforms, the I422 crystal form being obtained from high salt and the P21 crystal form beingobtained from lower concentration of salt and PEG. We report here the crystallization,preliminary stages of structure determination and the detection of the structural phasetransition in the P21 crystal form of G. sulphuraria RUBISCO. This red algae enzymebelongs to the hexadecameric class (L8S8 with an approximate molecular weight 0.6MDa.The phase transition in G. sulphuraria RUBISCO leads from two hexadecamers to a singlehexadecamer per asymmetric unit. The preservation of diffraction power in a phasetransition for such a large macromolecule is rare.

  16. Experimental study of micro-milling mechanism and surface quality of a nickel-based single crystal superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Qi; Gong, Yadong; Zhou, Yun Guang; Wen, Xue Long [School of Mechanical Engineering and Automation, Northeastern University, Shenyang (China)

    2017-01-15

    Micro-milling is widely used as a method for machining of micro-parts with high precision and efficiency. Taking the nickel-based single-crystal superalloy DD98 as the research object, the crystal characteristics of single-crystal materials were analysed, and the removal mechanism of single-crystal micro-milled parts was described. Based on molecular dynamics, a simulation model for nickel-based single-crystal superalloy DD98 micro-milling was established. Based on the response surface method of central composite design, the influences of spindle speed, feed rate, and milling depth on the surface roughness were examined, and a second-order regression model of the DD98 surface roughness was established. Using analysis of variance and the residuals of the model, a significant influence on surface roughness was found in the following order from large to small: Feed rate, spindle speed, and milling depth. Comparisons were conducted between the micro-milling experimental values and the predicted model values for different process parameters. The results show that the model fit is relatively high, and the adaptability is good. Scanning electron microscopy analysis of the micro-milling surfaces was performed to verify the slip and the removal mechanism of single-crystal materials. These results offer a theoretical reference and experimental basis for micro-milling of single-crystal materials.

  17. Synthesis and Characterization of a Chondroitin Sulfate Based Hybrid Bio/Synthetic Biomimetic Aggrecan Macromolecule

    Science.gov (United States)

    Sarkar, Sumona

    Lower back pain resulting from intervertebral disc degeneration is one of the leading musculoskeletal disorders confronting our health system. In order to mechanically stabilize the disc early in the degenerative cascade and prevent the need for spinal fusion surgeries, we have proposed the development of a hybrid-bio/synthetic biomimetic proteoglycan macromolecule for injection into the disc in the early stages of degeneration. The goal of this thesis was to incorporate natural chondroitin sulfate (CS) chains into bottle brush polymer synthesis strategies for the fabrication of CS-macromolecules which mimic the proteoglycan structure and function while resisting enzymatic degradation. Both the "grafting-to" and "grafting-through" techniques of bottle brush synthesis were explored. CS was immobilized via a terminal primary amine onto a model polymeric backbone (polyacrylic acid) for investigation of the "grafting-to" strategy and an epoxy-amine step-growth polymerization technique was utilized for the "grafting-through" synthesis of CS-macromolecules with polyethylene glycol backbone segments. Incorporation of a synthetic polymeric backbone at the terminal amine of CS was confirmed via biochemical assays, 1H-NMR and FTIR spectroscopy, and CS-macromolecule size was demonstrated to be higher than that of natural CS via gel permeation chromatography, transmission electron microscopy and viscosity measurements. Further analysis of CS-macromolecule functionality indicated maintenance of natural CS properties such as high fixed charge density, high osmotic potential and low cytotoxicity with nucleus pulposus cells. These studies are the first attempt at the incorporation of natural CS into biomimetic bottle brush structures. CS-macromolecules synthesized via the methods developed in these studies may be utilized in the treatment and prevention of debilitating back pain as well as act as mimetics for other proteoglycans implicated in cartilage, heart valve, and nervous

  18. Method for selective immobilization of macromolecules on self assembled monolayer surfaces

    Science.gov (United States)

    Laskin, Julia [Richland, WA; Wang, Peng [Billerica, MA

    2011-11-29

    Disclosed is a method for selective chemical binding and immobilization of macromolecules on solid supports in conjunction with self-assembled monolayer (SAM) surfaces. Immobilization involves selective binding of peptides and other macromolecules to SAM surfaces using reactive landing (RL) of mass-selected, gas phase ions. SAM surfaces provide a simple and convenient platform for tailoring chemical properties of a variety of substrates. The invention finds applications in biochemistry ranging from characterization of molecular recognition events at the amino acid level and identification of biologically active motifs in proteins, to development of novel biosensors and substrates for stimulated protein and cell adhesion.

  19. Click chemistry approach to functionalize two-dimensional macromolecules of graphene oxide nanosheets

    Institute of Scientific and Technical Information of China (English)

    Liang Kou; Hongkun He; Chao Gao

    2010-01-01

    A facile 'click chemistry' approach to functionalize 2D macromolecules of graphene oxide nanosheets with poly(ethylene glycol) of different molecular weights,polystyrene,palmitic acid and various amino acids was presented.FTIR,TGA,Raman spectroscopy,XPS,XRD,TEM,AFM and SEM were utilized to characterize the products.High degree of functionalization was achieved on the flat surfaces of graphene oxide,affording polymer-grafted 2D brushes and amino acids-immobilized nanosheets,which show improved solubility in organic solvents.The click chemistry strategy reported herein provides a facile and general method for functionalization of graphene oxide with macromolecules and desired biomolecules.

  20. Single molecule optical measurements of orientation and rotations of biological macromolecules.

    Science.gov (United States)

    Shroder, Deborah Y; Lippert, Lisa G; Goldman, Yale E

    2016-11-22

    Subdomains of macromolecules often undergo large orientation changes during their catalytic cycles that are essential for their activity. Tracking these rearrangements in real time opens a powerful window into the link between protein structure and functional output. Site-specific labeling of individual molecules with polarized optical probes and measurement of their spatial orientation can give insight into the crucial conformational changes, dynamics, and fluctuations of macromolecules. Here we describe the range of single molecule optical technologies that can extract orientation information from these probes, review the relevant types of probes and labeling techniques, and highlight the advantages and disadvantages of these technologies for addressing specific inquiries.

  1. Radiation Damage Mechanism in PbWO4 Crystal and Radiation Hardness Quality Control of PWO Scintillators for CMS

    CERN Document Server

    Baccaro, Stefania; Borgia, Bruno; Cavallari, Francesca; Cecilia, Angelica; Dafinei, Ioan; Diemoz, Marcella; Lecoq, Paul; Longo, Egidio; Montecchi, Marco; Organtini, Giovanni; Salvatori, S

    1997-01-01

    The optical damage induced by UV light in PbWO4 crystals is found to be similar to that induced by g radiation. Due to the peculiarities of optical absorption in PbWO4, the damage induced by UV light is a bulk process. This fact has important consequences for the approach to be adopted both for the use of the crystal as scintillator and for the qualification methods foreseen in the Regional Centres of the ECAL CMS Collaboration.

  2. Large and high-quality single-crystal growth of cuprate superconductor Bi-2223 using the traveling-solvent floating-zone (TSFZ) method

    Science.gov (United States)

    Adachi, Shintaro; Usui, Tomohiro; Kosugi, Kenta; Sasaki, Nae; Sato, Kentaro; Fujita, Masaki; Yamada, Kazuyoshi; Fujii, Takenori; Watanabe, Takao

    In high superconducting transition temperature (high-Tc) cuprates, it is empirically known that Tc increases on increasing the number of CuO2 planes in a unit cell n from 1 to 3. Bi-family cuprates are ideal for investigating the microscopic mechanism involved. However, it is difficult to grow tri-layered Bi-2223, probably owing to its narrow crystallization field. Here, we report improved crystal growth of this compound using the TSFZ method under conditions slightly different from those in an earlier report [J. Cryst. Growth 223, 175 (2001)]. A Bi-rich feed-rod composition of Bi2.2Sr1.9Ca2Cu3Oy and a slightly oxygen-reduced atmosphere (mixed gas flow of O2 (10%) and Ar (90%)) were adopted for the crystal growth. In addition, to increase the supersaturation of the melts, we applied a large temperature gradient along the solid-liquid interface by shielding a high-angle light beam using Al foil around the quartz tube. In this way, we succeeded in preparing large (2 × 2 × 0 . 05 mm3) and high-quality (almost 100% pure) Bi-2223 single crystals. Hirosaki University Grant for Exploratory Research by Young Scientists and Newly-appointed Scientists.

  3. Induced liquid-crystalline ordering in solutions of stiff and flexible amphiphilic macromolecules: Effect of mixture composition

    International Nuclear Information System (INIS)

    Glagolev, Mikhail K.; Vasilevskaya, Valentina V.; Khokhlov, Alexei R.

    2016-01-01

    Impact of mixture composition on self-organization in concentrated solutions of stiff helical and flexible macromolecules was studied by means of molecular dynamics simulation. The macromolecules were composed of identical amphiphilic monomer units but a fraction f of macromolecules had stiff helical backbones and the remaining chains were flexible. In poor solvents the compacted flexible macromolecules coexist with bundles or filament clusters from few intertwined stiff helical macromolecules. The increase of relative content f of helical macromolecules leads to increase of the length of helical clusters, to alignment of clusters with each other, and then to liquid-crystalline-like ordering along a single direction. The formation of filament clusters causes segregation of helical and flexible macromolecules and the alignment of the filaments induces effective liquid-like ordering of flexible macromolecules. A visual analysis and calculation of order parameter relaying the anisotropy of diffraction allow concluding that transition from disordered to liquid-crystalline state proceeds sharply at relatively low content of stiff components.

  4. A screening-corrected additivity rule for the calculation of electron scattering from macro-molecules

    International Nuclear Information System (INIS)

    Blanco, F; Garcia, G

    2009-01-01

    A simplified form of the well-known screening-corrected additivity rule procedure for the calculation of electron-molecule cross sections is proposed for the treatment of some very large macro-molecules. While the comparison of the standard and simplified treatments for a DNA dodecamer reveals very similar results, the new treatment presents some important advantages for large molecules.

  5. Probing nanoparticle-macromolecule interaction and resultant structure by small-angle neutron scattering

    International Nuclear Information System (INIS)

    Aswal, V.K.

    2013-01-01

    Nanoparticles display unique and distinct characteristics from those of their constituent atoms and bulk materials which are being employed in numerous applications in the fields of medicine, electronics, optics, communications, energy, environment etc. Many of these applications require adjoining of nanoparticles with macromolecules such as proteins, polymers and surfactants to obtain functional objects. For example, nanoparticle-protein complexes are of great importance in controlling enzymatic behavior, targeted drug delivery and developing biocompatible materials. The nanoparticles interfaced with polymers are shown to be useful in developing protein sensor arrays. Interaction of surfactants with nanoparticles is utilized extensively for technical and industrial applications associated with colloidal stability, detergency and design of nanostructured functional interfaces. The interaction of two components, nanoparticles and macromolecule, strongly depends on the characteristics of both the nanoparticles (size, shape, surface roughness, charge density etc.) and macromolecules (type, charge, shape and solution conditions etc.) used. The interaction of macromolecule on nanoparticle surface is a cumulative effect of a number of forces such as electrostatic force, covalent bonding, hydrogen bonding, non-polar interaction, hydrophobic interactions etc. These interactions depending on the system conditions can lead to various structures. Small-angle neutron scattering (SANS) with the possibility to vary contrast is an ideal technique to study such multi-component systems. In this talk, some of our results of SANS from the complexes of nanoparticle-protein and nanoparticle surfactant systems will be discussed. (author)

  6. Classification of the ejection mechanisms of charged macromolecules from liquid droplets.

    Science.gov (United States)

    Consta, Styliani; Malevanets, Anatoly

    2013-01-28

    The relation between the charge state of a macromolecule and its ejection mechanism from droplets is one of the important questions in electrospray ionization methods. In this article, effects of solvent-solute interaction on the manifestation of the charge induced instability in a droplet are examined. We studied the instabilities in a prototype system of a droplet comprised of charged poly(ethylene glycol) and methanol, acetonitrile, and water solvents. We observed instances of three, previously only conjectured, [S. Consta, J. Phys. Chem. B 114, 5263 (2010)] mechanisms of macroion ejection. The mechanism of ejection of charged macroion in methanol is reminiscent of "pearl" model in polymer physics. In acetonitrile droplets, the instability manifests through formation of solvent spines around the solvated macroion. In water, we find that the macroion is ejected from the droplet through contiguous extrusion of a part of the chain. The difference in the morphology of the instabilities is attributed to the interplay between forces arising from the macroion solvation energy and the surface energy of the droplet interface. For the contiguous extrusion of a charged macromolecule from a droplet, we demonstrate that the proposed mechanism leads to ejection of the macromolecule from droplets with sizes well below the Rayleigh limit. The ejected macromolecule may hold charge significantly higher than that suggested by prevailing theories. The simulations reveal new mechanisms of macroion evaporation that differ from conventional charge residue model and ion evaporation mechanisms.

  7. Simple and effective procedure for conformational search of macromolecules. Application to Met- and Leu-Enkephalin

    Energy Technology Data Exchange (ETDEWEB)

    Meirovitch, H.; Meirovitch, E. (Florida State Univ., Tallahassee, FL (United States)); Michel, A.G. (Institut de Recherches Serrier, Suresnes (France)); Vasquez, M. (Protein Design Lab., Mountain View, CA (United States))

    1994-06-23

    A simple and efficient method for searching the conformational space of macromolecules is presented. With this method an initial set of relatively low-energy structures is generated, and their energies are further minimized with a procedure that enables escaping from local energy minima. Illustrative calculations are described for Met- and Leu-enkephalin. 37 refs., 1 tab.

  8. The use of anomalous scattering of uranium for the determination of biological macromolecules structures - From hard to soft X-rays

    International Nuclear Information System (INIS)

    Chesne-Seck, M.L.

    2002-01-01

    In order to solve biological macromolecules structures, structure factor phases must be derived from the intensities diffracted by the crystal. The SAD and the MAD methods make use of variations in scattering factors measured at specific absorption edges of heavy atoms, bound to the protein. The phasing power depends on the occupancy of the binding sites and on the variations of the scattering factors at the absorption edge that is used. With uranyl, numerous sites with low occupancies are usually obtained. We used new colored uranyl complexes, which give higher occupancies, to solve de novo the lysozyme structure and an unknown structure. We have developed the use of the My absorption edge of uranium (λ = 3,5 Angstroms), where a variation of 120 electrons is observed in the scattering factors. With a helium atmosphere to limit the X-rays absorption, we have collected three data sets, on a single image. Data were processed both with 'classical' and specific programs. (author) [fr

  9. Traceable atomic force microscopy of high-quality solvent-free crystals of [6,6]-phenyl-C61-butyric acid methyl ester

    OpenAIRE

    Lazzerini, GM; Paterno, GM; Tregnago, G; Treat, N; Stingelin, N; Yacoot, A; Cacialli, F

    2016-01-01

    We report high-resolution, traceable atomic force microscopymeasurements of high-quality, solvent-free single crystals of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). These were grown by drop-casting PCBM solutions onto the spectrosil substrates and by removing the residual solvent in a vacuum. A home-built atomic force microscope featuring a plane mirror differential optical interferometer, fiber-fed from a frequency-stabilized laser (emitting at 632.8???nm), was used to measure the cr...

  10. Traceable atomic force microscopy of high-quality solvent-free crystals of [6,6]-phenyl-C-61-butyric acid methyl ester

    OpenAIRE

    Lazzerini, G. M.; Paterno, G. M.; Tregnago, G.; Treat, N.; Stingelin, N.; Yacoot, A.; Cacialli, F.

    2016-01-01

    We report high-resolution, traceable atomic force microscopymeasurements of high-quality, solvent-free single crystals of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). These were grown by drop-casting PCBM solutions onto the spectrosil substrates and by removing the residual solvent in a vacuum. A home-built atomic force microscope featuring a plane mirror differential optical interferometer, fiber-fed from a frequency-stabilized laser (emitting at 632.8 nm), was used to measure the crys...

  11. An improved strategy for the crystallization of Leishmania mexicana pyruvate kinase

    International Nuclear Information System (INIS)

    Morgan, Hugh P.; McNae, Iain W.; Hsin, Kun-Yi; Michels, Paul A. M.; Fothergill-Gilmore, Linda A.; Walkinshaw, Malcolm D.

    2010-01-01

    The first crystal structure of Leishmania mexicana pyruvate kinase (LmPYK) obtained at a neutral pH. LmPYK was co-crystallized with the small molecule 1,3,6,8-pyrenetetrasulfonic acid, which provides a helpful intermolecular bridge between macromolecules. The inclusion of novel small molecules in crystallization experiments has provided very encouraging results and this method is now emerging as a promising alternative strategy for crystallizing ‘problematic’ biological macromolecules. These small molecules have the ability to promote lattice formation through stabilizing intermolecular interactions in protein crystals. Here, the use of 1,3,6,8-pyrenetetrasulfonic acid (PTS), which provides a helpful intermolecular bridge between Leishmania mexicana PYK (LmPYK) macromolecules in the crystal, is reported, resulting in the rapid formation of a more stable crystal lattice at neutral pH and greatly improved X-ray diffraction results. The refined structure of the LmPYK–PTS complex revealed the negatively charged PTS molecule to be stacked between positively charged (surface-exposed) arginine side chains from neighbouring LmPYK molecules in the crystal lattice

  12. Free diffusion of translation of macromolecules in solution with the rayleigh interferometer; Diffusion libre de translation des macromolecules en solution, par interferometrie de rayleigh

    Energy Technology Data Exchange (ETDEWEB)

    Leger, J J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    The aim of this study is to develop a rapid and accurate measurement, with the Rayleigh interferometer, of the free diffusion coefficient of translation of macromolecules in solution. After having explained the choice of a diffusion cell with laminar lateral flow, and explained the principle of the Rayleigh interferometer, a semi-automatic technique of free diffusion are then introduced. Solutions are proposed for systems composed of two or three components, such as biopolymers. The paper ends by drafting the possible treatment of recorded experimental data by means of electronic computer. (author) [French] Cette etude a ete entreprise pour mettre au point une methode precise et rapide de mesure, par interferometre de Rayleigh, du coefficient de diffusion libre de translation des macromolecules en solution. Apres avoir justifie le choix d'une cellule de diffusion a ecoulement laminaire lateral et explique le principe de l'interferometre de Rayleigh, l'auteur decrit une technique semi-automatique d'enregistrement des cliches d'interference. Il introduit ensuite les equations differentielles de diffusion libre et propose des solutions pour les systemes a deux et trois composants applicables aux biopolymeres. L'article se termine par une esquisse concernant le traitement des donnees experimentales enregistrees au moyen du calcul electronique. (auteur)

  13. Single-crystal SrTiO3 fiber grown by laser heated pedestal growth method: influence of ceramic feed rod preparation in fiber quality

    Directory of Open Access Journals (Sweden)

    D. Reyes Ardila

    1998-10-01

    Full Text Available The rapidly spreading use of optical fiber as a transmission medium has created an interest in fiber-compatible optical devices and methods for growing them, such as the Laser Heated Pedestal Growth (LHPG. This paper reports on the influence of the ceramic feed rod treatment on fiber quality and optimization of ceramic pedestal processing that allows improvements to be made on the final quality in a simple manner. Using the LHPG technique, transparent crack-free colorless single crystal fibers of SrTiO3 (0.50 mm in diameter and 30-40 mm in length were grown directly from green-body feed rods, without using external oxygen atmosphere.

  14. Marine-derived biological macromolecule-based biomaterials for wound healing and skin tissue regeneration.

    Science.gov (United States)

    Chandika, Pathum; Ko, Seok-Chun; Jung, Won-Kyo

    2015-01-01

    Wound healing is a complex biological process that depends on the wound condition, the patient's health, and the physicochemical support given through external materials. The development of bioactive molecules and engineered tissue substitutes to provide physiochemical support to enhance the wound healing process plays a key role in advancing wound-care management. Thus, identification of ideal molecules in wound treatment is still in progress. The discovery of natural products that contain ideal molecules for skin tissue regeneration has been greatly advanced by exploration of the marine bioenvironment. Consequently, tremendously diverse marine organisms have become a great source of numerous biological macromolecules that can be used to develop tissue-engineered substitutes with wound healing properties. This review summarizes the wound healing process, the properties of macromolecules from marine organisms, and the involvement of these molecules in skin tissue regeneration applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Interactions between macromolecule-bound antioxidants and Trolox during liposome autoxidation

    DEFF Research Database (Denmark)

    Celik, Ecem Evrim; Amigo Rubio, Jose Manuel; Andersen, Mogens Larsen

    2017-01-01

    The interactions between free and macromolecule-bound antioxidants were investigated in order to evaluate their combined effects on the antioxidant environment. Dietary fiber (DF), protein and lipid-bound antioxidants, obtained from whole wheat, soybean and olive oil products, respectively and Tr...... of logistic function was successfully used for modelling the oxidation curve of liposomes. Principal component analysis revealed two separate phases of liposome autoxidation.......The interactions between free and macromolecule-bound antioxidants were investigated in order to evaluate their combined effects on the antioxidant environment. Dietary fiber (DF), protein and lipid-bound antioxidants, obtained from whole wheat, soybean and olive oil products, respectively...... of the simple addition effects of Trolox and bound antioxidants with measured values on lipid oxidation revealed synergetic interactions for DF and refined olive oil-bound antioxidants, and antagonistic interactions for protein and extra virgin olive oil-bound antioxidants with Trolox. A generalized version...

  16. Macromolecule simulation and CH{sub 4} adsorption mechanism of coal vitrinite

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Song, E-mail: songyu10094488@126.com [School of Resources and Earth Science, China University of Mining & Technology, Xuzhou 221116 (China); Key Laboratory of Coal bed Methane Resource & Reservoir Formation Process, Ministry of Education, Xuzhou 221008 (China); Yan-ming, Zhu; Wu, Li [School of Resources and Earth Science, China University of Mining & Technology, Xuzhou 221116 (China); Key Laboratory of Coal bed Methane Resource & Reservoir Formation Process, Ministry of Education, Xuzhou 221008 (China)

    2017-02-28

    Highlights: • Molecular model of single maceral vitrinite was obtained by {sup 13}C NMR, FT IR and HRTEM. • An optimal configuration was obtained through calculation of MM and MD. • The adsorption parameters for methane and vitrinite were determined with DFT and GCMC. - Abstract: The microscopic mechanism of interactions between CH{sub 4} and coal macromolecules is of significant practical and theoretical importance in CBM development and methane storage. Under periodic boundary conditions, the optimal energy configuration of coal vitrinite, which has a higher torsion degree and tighter arrangement, can be determined by the calculation of molecular mechanics (MM) and molecular dynamics (MD), and annealing kinetics simulation based on ultimate analysis, {sup 13}C NMR, FT IR and HRTEM. Macromolecular stabilization is primarily due to the van der Waals energy and covalent bond energy, mainly consisting of bond torsion energy and bond angle energy. Using the optimal configuration as the adsorbent, GCMC simulation of vitrinite adsorption of CH{sub 4} is conducted. A saturated state is reached after absorbing 17 CH{sub 4}s per coal vitrinite molecule. CH{sub 4} is preferentially adsorbed on the edge, and inclined to gathering around the branched chains of the inner vitrinite sites. Finally, the adsorption parameters are calculated through first principle DFT. The adsorbability order is as follows: aromatic structure> heteroatom rings > oxygen functional groups. The adsorption energy order is as follows: Top < Bond < Center, Up < Down. The order of average RDF better reflects the adsorption ability and that of [-COOH] is lower than those of [−C=O] and [C−O−C]. CH{sub 4} distributed in the distance of 0.99–16 Å to functional groups in the type of monolayer adsorption and the average distance order manifest as [−C=O] (1.64 Å) < [C−O−C] (1.89 Å) < [−COOH] (3.78 Å) < [-CH{sub 3}] (4.11 Å) according to the average RDF curves. CH{sub 4} enriches

  17. Production of polarizing Heusler crystals

    Energy Technology Data Exchange (ETDEWEB)

    Courtois, P. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1999-11-01

    Heusler crystals simultaneously produce monochromatized and polarized neutrons. However, in the past, it was difficult to produce these crystals. In collaboration with the neutron scattering group of CEA Grenoble and LLB Saclay, the production of high quality Heusler crystals has been established at ILL. (author) 3 refs., 2 figs., 1 tab.

  18. Chemical species of iodine in some seaweeds. Pt. 2. Iodine-bound biological macromolecules

    International Nuclear Information System (INIS)

    Xiaolin Hou; Chifang Chai; Xiaojun Yan

    2000-01-01

    The distribution of iodine in various biological macromolecules in Sargassum kjellmanianum was studied using neutron activation analysis combined with chemical and biochemical separation techniques. The results indicate that iodine is mainly bound with protein, part of iodine with pigment and polyphenol, and little with polysaccharides, such as algin, fucoidan and cellulose. This result is significant for the mechanism of enriching iodine of algae and utilization of alga iodine. (author)

  19. Synthetic mimetics of the endogenous gastrointestinal nanomineral: Silent constructs that trap macromolecules for intracellular delivery.

    Science.gov (United States)

    Pele, Laetitia C; Haas, Carolin T; Hewitt, Rachel E; Robertson, Jack; Skepper, Jeremy; Brown, Andy; Hernandez-Garrido, Juan Carlos; Midgley, Paul A; Faria, Nuno; Chappell, Helen; Powell, Jonathan J

    2017-02-01

    Amorphous magnesium-substituted calcium phosphate (AMCP) nanoparticles (75-150nm) form constitutively in large numbers in the mammalian gut. Collective evidence indicates that they trap and deliver luminal macromolecules to mucosal antigen presenting cells (APCs) and facilitate gut immune homeostasis. Here, we report on a synthetic mimetic of the endogenous AMCP and show that it has marked capacity to trap macromolecules during formation. Macromolecular capture into AMCP involved incorporation as shown by STEM tomography of the synthetic AMCP particle with 5nm ultra-fine iron (III) oxohydroxide. In vitro, organic cargo-loaded synthetic AMCP was taken up by APCs and tracked to lysosomal compartments. The AMCP itself did not regulate any gene, or modify any gene regulation by its cargo, based upon whole genome transcriptomic analyses. We conclude that synthetic AMCP can efficiently trap macromolecules and deliver them to APCs in a silent fashion, and may thus represent a new platform for antigen delivery. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

  20. Prevention of H-Aggregates Formation in Cy5 Labeled Macromolecules

    Directory of Open Access Journals (Sweden)

    Jing Kang

    2010-01-01

    Full Text Available H-aggregates of the cyanine dye Cy5 are formed during covalent linkage to the cationic macromolecule Poly(allylamine (PAH. The nonfluorescent H-aggregates strongly restrict the usage of the dye for analytical purposes and prevent a quantitative determination of the labeled macromolecules. The behavior of the H-aggregates has been studied by investigation of the absorption and fluorescence spectra of the dye polymer in dependence on solvent, label degree and additional sulfonate groups. H-aggregate formation is caused by an inhomogeneous distribution of the Cy5 molecules on the polymer chain. The H-aggregates can be destroyed by conformational changes of the PAH induced by interactions with polyanions or in organic solvents. It has been found that the polymer labeling process in high content of organic solvents can prevent the formation of H-aggregates. The results offer a better understanding and improvement of the use of the Cy5 dye for labeling purposes in fluorescence detection of macromolecules.

  1. Scalable synthesis of sequence-defined, unimolecular macromolecules by Flow-IEG

    Science.gov (United States)

    Leibfarth, Frank A.; Johnson, Jeremiah A.; Jamison, Timothy F.

    2015-01-01

    We report a semiautomated synthesis of sequence and architecturally defined, unimolecular macromolecules through a marriage of multistep flow synthesis and iterative exponential growth (Flow-IEG). The Flow-IEG system performs three reactions and an in-line purification in a total residence time of under 10 min, effectively doubling the molecular weight of an oligomeric species in an uninterrupted reaction sequence. Further iterations using the Flow-IEG system enable an exponential increase in molecular weight. Incorporating a variety of monomer structures and branching units provides control over polymer sequence and architecture. The synthesis of a uniform macromolecule with a molecular weight of 4,023 g/mol is demonstrated. The user-friendly nature, scalability, and modularity of Flow-IEG provide a general strategy for the automated synthesis of sequence-defined, unimolecular macromolecules. Flow-IEG is thus an enabling tool for theory validation, structure–property studies, and advanced applications in biotechnology and materials science. PMID:26269573

  2. Friction of N-bead macromolecules in solution: Effects of the bead-solvent interaction

    International Nuclear Information System (INIS)

    Uvarov, Alexander; Fritzsche, Stephan

    2006-01-01

    The role of the bead-solvent interaction has been studied for its influence on the dynamics of an N-bead macromolecule which is immersed into a solution. Using a Fokker-Planck equation for the phase-space distribution function of the macromolecule, we show that all the effects of the solution can be treated entirely in terms of the friction tensors which are assigned to each pair of interacting beads in the chain. For the high-density as well as for the critical solvent, the properties of these tensors are discussed in detail and are calculated by using several (realistic) choices of the bead-solvent potential. From the friction tensors, moreover, an expression for the center-of-mass friction coefficient of a (N-bead) chain macromolecule is derived. Numerical data for this coefficient for 'truncated' Lennard-Jones bead-solvent potential are compared with results from molecular dynamic simulations and from the phenomenological theoretical data as found in the literature

  3. Application of Symmetry Adapted Function Method for Three-Dimensional Reconstruction of Octahedral Biological Macromolecules

    Directory of Open Access Journals (Sweden)

    Songjun Zeng

    2010-01-01

    Full Text Available A method for three-dimensional (3D reconstruction of macromolecule assembles, that is, octahedral symmetrical adapted functions (OSAFs method, was introduced in this paper and a series of formulations for reconstruction by OSAF method were derived. To verify the feasibility and advantages of the method, two octahedral symmetrical macromolecules, that is, heat shock protein Degp24 and the Red-cell L Ferritin, were utilized as examples to implement reconstruction by the OSAF method. The schedule for simulation was designed as follows: 2000 random orientated projections of single particles with predefined Euler angles and centers of origins were generated, then different levels of noises that is signal-to-noise ratio (S/N =0.1,0.5, and 0.8 were added. The structures reconstructed by the OSAF method were in good agreement with the standard models and the relative errors of the structures reconstructed by the OSAF method to standard structures were very little even for high level noise. The facts mentioned above account for that the OSAF method is feasible and efficient approach to reconstruct structures of macromolecules and have ability to suppress the influence of noise.

  4. Formation and characterization of calcium orthophosphates in the presence of two different acidic macromolecules

    Science.gov (United States)

    Pelin, Irina M.; Maier, Vasilica; Suflet, Dana M.; Popescu, Irina; Darie-Nita, Raluca N.; Aflori, Magdalena; Butnaru, Maria

    2017-10-01

    The synthetic nanocrystalline calcium orthophosphates have a notable bioactivity due to the chemical similarity with biological apatite from calcified tissues. In mineralized tissues, the highly ordered structures come from organized assemblies of biomacromolecules and inorganic nanoparticles. One of the purposes of this work was to study the effect of two types of acidic macromolecules: atelocollagen and phosphorylated curdlan onto calcium orthophosphates formation after 30 days of maturation at 2 ± 2 °C. The resulted samples after a long aging time, either calcium orthophosphates or composites, were first investigated by FT-IR spectroscopy and X-ray diffractometry and the results indicated that precipitated hydroxyapatite with low crystallinity was obtained when the synthesis was performed in the presence of phosphorylated curdlan. The macromolecules influenced the morphology of the particles as shown by scanning and transmission electron microscopy. The presence of macromolecules as demonstrated by thermal investigation also influenced the rheological properties of the samples. The second purpose of the work was to evaluate the cytotoxicity of the samples using the MTT assay, and the results revealed very good cells viability. The preliminary results are encouraging regarding the use of these materials for further tests in order to develop injectable bone substitutes.

  5. Nasal Absorption of Macromolecules from Powder Formulations and Effects of Sodium Carboxymethyl Cellulose on Their Absorption.

    Directory of Open Access Journals (Sweden)

    Akiko Tanaka

    Full Text Available The nasal absorption of macromolecules from powder formulations and the effect of sodium carboxymethyl cellulose (CMC-Na as a pharmaceutical excipient on their absorption were studied. Model macromolecules were fluorescein isothiocyanate-labeled dextran (average molecular weight of 4.4kDa, FD4 and insulin. The plasma concentration of FD4 after application of the powder containing 50% starch (control was higher than that after application of the solution, and the absorption from 50% starch powder was enhanced by the substitution of starch with CMC-Na. The fractional absorption of FD4 after administration of the CMC-Na powder formulation was 30% and 40% higher than that after administration from the solution and the starch powder, respectively. The nasal absorption of insulin from the powder and the effect of CMC-Na were similar with those of FD4. The effective absorption of FD4 and insulin after application of powder with CMC-Na could be due to the increase in the nasal residence of FD4 and insulin. No damage in the nasal mucosa or dysfunction of the mucociliary clearance was observed after application of the drug powder and CMC-Na. The present findings indicate that nasal delivery of powder formulations with the addition of CMC-Na as an excipient is a promising approach for improving the nasal absorption of macromolecules.

  6. Lignin Macromolecule

    Indian Academy of Sciences (India)

    plant or a structural component of a mature plant which is detected by certain colour reactions. An enzymologist has termed lignin as the ... a phenyl-propanoid structure. A soil chemist considers lignin to be the residue of .... refer to the hardness of wood, but to the botanical classifications. They are aptly called gymnosperms ...

  7. Nanometer-scale structure of alkali-soluble bio-macromolecules of maize plant residues explains their recalcitrance in soil.

    Science.gov (United States)

    Adani, Fabrizio; Salati, Silvia; Spagnol, Manuela; Tambone, Fulvia; Genevini, Pierluigi; Pilu, Roberto; Nierop, Klaas G J

    2009-07-01

    The quantity and quality of plant litter in the soil play an important role in the soil organic matter balance. Besides other pedo-climatic aspects, the content of recalcitrant molecules of plant residues and their chemical composition play a major role in the preservation of plant residues. In this study, we report that intrinsically resistant alkali-soluble bio-macromolecules extracted from maize plant (plant-humic acid) (plant-HA) contribute directly to the soil organic matter (OM) by its addition and conservation in the soil. Furthermore, we also observed that a high syringyl/guaiacyl (S/G) ratio in the lignin residues comprising the plant tissue, which modifies the microscopic structure of the alkali-soluble plant biopolymers, enhances their recalcitrance because of lower accessibility of molecules to degrading enzymes. These results are in agreement with a recent study, which showed that the humic substance of soil consists of a mixture of identifiable biopolymers obtained directly from plant tissues that are added annually by maize plant residues.

  8. Automation in biological crystallization.

    Science.gov (United States)

    Stewart, Patrick Shaw; Mueller-Dieckmann, Jochen

    2014-06-01

    Crystallization remains the bottleneck in the crystallographic process leading from a gene to a three-dimensional model of the encoded protein or RNA. Automation of the individual steps of a crystallization experiment, from the preparation of crystallization cocktails for initial or optimization screens to the imaging of the experiments, has been the response to address this issue. Today, large high-throughput crystallization facilities, many of them open to the general user community, are capable of setting up thousands of crystallization trials per day. It is thus possible to test multiple constructs of each target for their ability to form crystals on a production-line basis. This has improved success rates and made crystallization much more convenient. High-throughput crystallization, however, cannot relieve users of the task of producing samples of high quality. Moreover, the time gained from eliminating manual preparations must now be invested in the careful evaluation of the increased number of experiments. The latter requires a sophisticated data and laboratory information-management system. A review of the current state of automation at the individual steps of crystallization with specific attention to the automation of optimization is given.

  9. Investigating the nucleation of protein crystals with hydrostatic pressure

    Energy Technology Data Exchange (ETDEWEB)

    Kadri, A [Departement ' Mecanismes et Macromolecules de la Synthese Proteique et Cristallogenese' UPR 9002, Institut de Biologie Moleculaire et Cellulaire du CNRS, 15 rue Rene Descartes, F-67084 Strasbourg Cedex (France); Damak, M [Laboratoire de Chimie des Substances Naturelles, Faculte des Sciences de Sfax, BP 802, 3018 Sfax (Tunisia); Jenner, G [Laboratoire de Piezochimie Organique, UMR 7123, Faculte de Chimie, Universite Louis Pasteur, 1 rue Blaise Pascal, F-67008 Strasbourg Cedex (France); Lorber, B [Departement ' Mecanismes et Macromolecules de la Synthese Proteique et Cristallogenese' UPR 9002, Institut de Biologie Moleculaire et Cellulaire du CNRS, 15 rue Rene Descartes, F-67084 Strasbourg Cedex (France); Giege, R [Departement ' Mecanismes et Macromolecules de la Synthese Proteique et Cristallogenese' UPR 9002, Institut de Biologie Moleculaire et Cellulaire du CNRS, 15 rue Rene Descartes, F-67084 Strasbourg Cedex (France)

    2003-12-17

    Hydrostatic pressure in the 0.1-75 MPa range has been used as a non-invasive tool to study the crystallization process of the tetragonal crystal form of the protein thaumatin (M{sub r} 22 200). Crystals were prepared within agarose gel and at temperatures in the range from 283 to 303 K. The solubility, i.e. the concentration of soluble macromolecules remaining in equilibrium with the crystals, decreases when the pressure increases and when the temperature decreases. High pressure was used to probe the nucleation behaviour of thaumatin. The pressure dependence of the nucleation rate leads to an activation volume of -46.5cm{sup 3} mol{sup -1}. It is shown that an increase in pressure decreases the enthalpy, the entropy and the free energy of crystallization of thaumatin. The data are discussed in the light of the results of crystallographic analyses and of the structure of the protein.

  10. Investigating the nucleation of protein crystals with hydrostatic pressure

    International Nuclear Information System (INIS)

    Kadri, A; Damak, M; Jenner, G; Lorber, B; Giege, R

    2003-01-01

    Hydrostatic pressure in the 0.1-75 MPa range has been used as a non-invasive tool to study the crystallization process of the tetragonal crystal form of the protein thaumatin (M r 22 200). Crystals were prepared within agarose gel and at temperatures in the range from 283 to 303 K. The solubility, i.e. the concentration of soluble macromolecules remaining in equilibrium with the crystals, decreases when the pressure increases and when the temperature decreases. High pressure was used to probe the nucleation behaviour of thaumatin. The pressure dependence of the nucleation rate leads to an activation volume of -46.5cm 3 mol -1 . It is shown that an increase in pressure decreases the enthalpy, the entropy and the free energy of crystallization of thaumatin. The data are discussed in the light of the results of crystallographic analyses and of the structure of the protein

  11. Organic semiconductor crystals.

    Science.gov (United States)

    Wang, Chengliang; Dong, Huanli; Jiang, Lang; Hu, Wenping

    2018-01-22

    Organic semiconductors have attracted a lot of attention since the discovery of highly doped conductive polymers, due to the potential application in field-effect transistors (OFETs), light-emitting diodes (OLEDs) and photovoltaic cells (OPVs). Single crystals of organic semiconductors are particularly intriguing because they are free of grain boundaries and have long-range periodic order as well as minimal traps and defects. Hence, organic semiconductor crystals provide a powerful tool for revealing the intrinsic properties, examining the structure-property relationships, demonstrating the important factors for high performance devices and uncovering fundamental physics in organic semiconductors. This review provides a comprehensive overview of the molecular packing, morphology and charge transport features of organic semiconductor crystals, the control of crystallization for achieving high quality crystals and the device physics in the three main applications. We hope that this comprehensive summary can give a clear picture of the state-of-art status and guide future work in this area.

  12. Increased Plasma Colloid Osmotic Pressure Facilitates the Uptake of Therapeutic Macromolecules in a Xenograft Tumor Model

    Directory of Open Access Journals (Sweden)

    Matthias Hofmann

    2009-08-01

    Full Text Available Elevated tumor interstitial fluid pressure (TIFP is a characteristic of most solid tumors. Clinically, TIFP may hamper the uptake of chemotherapeutic drugs into the tumor tissue reducing their therapeutic efficacy. In this study, a means of modulating TIFP to increase the flux of macromolecules into tumor tissue is presented, which is based on the rationale that elevated plasma colloid osmotic pressure (COP pulls water from tumor interstitium lowering the TIFP. Concentrated human serum albumin: (20% HSA, used as an agent to enhance COP, reduced the TIFP time-dependently from 8 to 2 mm Hg in human tumor xenograft models bearing A431 epidermoid vulva carcinomas. To evaluate whether this reduction facilitates the uptake of macromolecules, the intratumoral distribution of fluorescently conjugated dextrans (2.5 mg/ml and cetuximab (2.0 mg/ml was probed using novel time domain nearinfrared fluorescence imaging. This method permitted discrimination and semiquantification of tumor-accumulated conjugate from background and unspecific probe fluorescence. The coadministration of 20% HSA together with either dextrans or cetuximab was found to lower the TIFP significantly and increase the concentration of the substances within the tumor tissue in comparison to control tumors. Furthermore, combined administration of 20%HSA plus cetuximab reduced the tumor growth significantly in comparison to standard cetuximab treatment. These data demonstrate that increased COP lowers the TIFP within hours and increases the uptake of therapeutic macromolecules into the tumor interstitium leading to reduced tumor growth. This model represents a novel approach to facilitate the delivery of therapeutics into tumor tissue, particularly monoclonal antibodies.

  13. Visualization of three pathways for macromolecule transport across cultured endothelium and their modification by flow.

    Science.gov (United States)

    Ghim, Mean; Alpresa, Paola; Yang, Sung-Wook; Braakman, Sietse T; Gray, Stephen G; Sherwin, Spencer J; van Reeuwijk, Maarten; Weinberg, Peter D

    2017-11-01

    Transport of macromolecules across vascular endothelium and its modification by fluid mechanical forces are important for normal tissue function and in the development of atherosclerosis. However, the routes by which macromolecules cross endothelium, the hemodynamic stresses that maintain endothelial physiology or trigger disease, and the dependence of transendothelial transport on hemodynamic stresses are controversial. We visualized pathways for macromolecule transport and determined the effect on these pathways of different types of flow. Endothelial monolayers were cultured under static conditions or on an orbital shaker producing different flow profiles in different parts of the wells. Fluorescent tracers that bound to the substrate after crossing the endothelium were used to identify transport pathways. Maps of tracer distribution were compared with numerical simulations of flow to determine effects of different shear stress metrics on permeability. Albumin-sized tracers dominantly crossed the cultured endothelium via junctions between neighboring cells, high-density lipoprotein-sized tracers crossed at tricellular junctions, and low-density lipoprotein-sized tracers crossed through cells. Cells aligned close to the angle that minimized shear stresses across their long axis. The rate of paracellular transport under flow correlated with the magnitude of these minimized transverse stresses, whereas transport across cells was uniformly reduced by all types of flow. These results contradict the long-standing two-pore theory of solute transport across microvessel walls and the consensus view that endothelial cells align with the mean shear vector. They suggest that endothelial cells minimize transverse shear, supporting its postulated proatherogenic role. Preliminary data show that similar tracer techniques are practicable in vivo. NEW & NOTEWORTHY Solutes of increasing size crossed cultured endothelium through intercellular junctions, through tricellular

  14. Free diffusion of translation of macromolecules in solution with the rayleigh interferometer

    International Nuclear Information System (INIS)

    Leger, J.J.

    1969-01-01

    The aim of this study is to develop a rapid and accurate measurement, with the Rayleigh interferometer, of the free diffusion coefficient of translation of macromolecules in solution. After having explained the choice of a diffusion cell with laminar lateral flow, and explained the principle of the Rayleigh interferometer, a semi-automatic technique of free diffusion are then introduced. Solutions are proposed for systems composed of two or three components, such as biopolymers. The paper ends by drafting the possible treatment of recorded experimental data by means of electronic computer. (author) [fr

  15. Isolation of cell nuclei using inert macromolecules to mimic the crowded cytoplasm.

    Directory of Open Access Journals (Sweden)

    Ronald Hancock

    Full Text Available Cell nuclei are commonly isolated and studied in media which include millimolar concentrations of cations, which conserve the nuclear volume by screening the negative charges on chromatin and maintaining its compaction. However, two factors question if these ionic conditions correctly reproduce the environment of nuclei in vivo: the small-scale motion and conformation of chromatin in vivo are not reproduced in isolated nuclei, and experiments and theory suggest that small ions in the cytoplasm are not free in the soluble phase but are predominantly bound to macromolecules. We studied the possible role in maintaining the structure and functions of nuclei in vivo of a further but frequently overlooked property of the cytoplasm, the crowding or osmotic effects caused by diffusible macromolecules whose concentration, measured in several studies, is in the range of 130 mg/ml. Nuclei which conserved their volume in the cell and their ultrastructure seen by electron microscopy were released from K562 cells in media containing the inert polymer 70 kDa Ficoll (50% w/v or 70 kDa dextran (35% w/v to replace the diffusible cytoplasmic molecules which were dispersed on cell lysis with digitonin, with 100 microM K-Hepes buffer as the only source of ions. Immunofluorescence labelling and experiments using cells expressing GFP-fusion proteins showed that internal compartments (nucleoli, PML and coiled bodies, foci of RNA polymerase II were conserved in these nuclei, and nascent RNA transcripts could be elongated. Our observations are consistent with the hypothesis that crowding by diffusible cytoplasmic macromolecules is a crucial but overlooked factor which supports the nucleus in vivo by equilibrating the opposing osmotic pressure cause by the high concentration of macromolecules in the nucleus, and suggest that crowded media provide more physiological conditions to study nuclear structure and functions. They may also help to resolve the long-standing paradox

  16. Hypersonic phononic crystals.

    Science.gov (United States)

    Gorishnyy, T; Ullal, C K; Maldovan, M; Fytas, G; Thomas, E L

    2005-03-25

    In this Letter we propose the use of hypersonic phononic crystals to control the emission and propagation of high frequency phonons. We report the fabrication of high quality, single crystalline hypersonic crystals using interference lithography and show that direct measurement of their phononic band structure is possible with Brillouin light scattering. Numerical calculations are employed to explain the nature of the observed propagation modes. This work lays the foundation for experimental studies of hypersonic crystals and, more generally, phonon-dependent processes in nanostructures.

  17. Ductile polyelectrolyte macromolecule-complexed zinc phosphate conversion crystal pre-coatings and topcoatings embodying a laminate

    Science.gov (United States)

    Sugama, Toshifumi; Kukacka, Lawrence E.; Carciello, Neal R.

    1987-01-01

    This invention relates to a precoat, laminate, and method for ductile coatings on steel and non-ferrous metals which comprises applying a zinc phosphating coating solution modified by a solid polyelectrolyte selected from polyacrylic acid (PAA), polymethacrylic acid (PMA), polyitaconic acid (PIA), and poly-L-glutamic acid. The contacting of the resin with the phosphating solution is made for a period of up to 20 hours at about 80.degree. C. The polyelectrolyte or the precoat is present in about 0.5-5.0% by weight of the total precoat composition and after application, the precoat base is dried for up to 5 hours at about 150.degree. C. to desiccate. Also, a laminate may be formed where polyurethane (PU) is applied as an elastomeric topcoating or polyfuran resin is applied as a glassy topcoating. It has been found that the use of PAA at a molecular weight of about 2.times.10.sup.5 gave improved ductility modulus effect.

  18. Crystals in crystals

    DEFF Research Database (Denmark)

    Christensen, Claus H.; Schmidt, I.; Carlsson, A.

    2005-01-01

    A major factor governing the performance of catalytically active particles supported on a zeolite carrier is the degree of dispersion. It is shown that the introduction of noncrystallographic mesopores into zeolite single crystals (silicalite-1, ZSM-5) may increase the degree of particle dispersion....... As representative examples, a metal (Pt), an alloy (PtSn), and a metal carbide (beta-Mo2C) were supported on conventional and mesoporous zeolite carriers, respectively, and the degree of particle dispersion was compared by TEM imaging. On conventional zeolites, the supported material aggregated on the outer surface...

  19. Virtual Crystallizer

    Energy Technology Data Exchange (ETDEWEB)

    Land, T A; Dylla-Spears, R; Thorsness, C B

    2006-08-29

    Large dihydrogen phosphate (KDP) crystals are grown in large crystallizers to provide raw material for the manufacture of optical components for large laser systems. It is a challenge to grow crystal with sufficient mass and geometric properties to allow large optical plates to be cut from them. In addition, KDP has long been the canonical solution crystal for study of growth processes. To assist in the production of the crystals and the understanding of crystal growth phenomena, analysis of growth habits of large KDP crystals has been studied, small scale kinetic experiments have been performed, mass transfer rates in model systems have been measured, and computational-fluid-mechanics tools have been used to develop an engineering model of the crystal growth process. The model has been tested by looking at its ability to simulate the growth of nine KDP boules that all weighed more than 200 kg.

  20. single crystals

    Indian Academy of Sciences (India)

    2018-05-18

    May 18, 2018 ... Abstract. 4-Nitrobenzoic acid (4-NBA) single crystals were studied for their linear and nonlinear optical ... studies on the proper growth, linear and nonlinear optical ..... between the optic axes and optic sign of the biaxial crystal.

  1. Crystal Systems.

    Science.gov (United States)

    Schomaker, Verner; Lingafelter, E. C.

    1985-01-01

    Discusses characteristics of crystal systems, comparing (in table format) crystal systems with lattice types, number of restrictions, nature of the restrictions, and other lattices that can accidently show the same metrical symmetry. (JN)

  2. Food macromolecule based nanodelivery systems for enhancing the bioavailability of polyphenols

    Directory of Open Access Journals (Sweden)

    Bing Hu

    2017-01-01

    Full Text Available Diet polyphenols—primarily categorized into flavonoids (e.g., flavonols, flavones, flavan-3-ols, anthocyanidins, flavanones, and isoflavones and nonflavonoids (with major subclasses of stilbenes and phenolic acids—are reported to have health-promoting effects, such as antioxidant, antiinflammatory, anticarcinoma, antimicrobial, antiviral, and cardioprotective properties. However, their applications in functional foods or medicine are limited because of their inefficient systemic delivery and poor oral bioavailability. Epigallocatechin-3-gallate, curcumin, and resveratrol are the well-known representatives of the bioactive diet polyphenols but with poor bioavailability. Food macromolecule based nanoparticles have been fabricated using reassembled proteins, crosslinked polysaccharides, protein–polysaccharide conjugates (complexes, as well as emulsified lipid via safe procedures that could be applied in food. The human gastrointestinal digestion tract is the first place where the food grade macromolecule nanoparticles exert their effects on improving the bioavailability of diet polyphenols, via enhancing their solubility, preventing their degradation in the intestinal environment, elevating the permeation in small intestine, and even increasing their contents in the bloodstream. We contend that the stability and structure behaviors of nanocarriers in the gastrointestinal tract environment and the effects of nanoencapsulation on the metabolism of polyphenols warrant more focused attention in further studies.

  3. Ordered mesoporous polymer-silica hybrid nanoparticles as vehicles for the intracellular controlled release of macromolecules.

    Science.gov (United States)

    Kim, Tae-Wan; Slowing, Igor I; Chung, Po-Wen; Lin, Victor Shang-Yi

    2011-01-25

    A two-dimensional hexagonal ordered mesoporous polymer-silica hybrid nanoparticle (PSN) material was synthesized by polymerization of acrylate monomers on the surface of SBA-15 mesoporous silica nanoparticles. The structure of the PSN material was analyzed using a series of different techniques, including transmission electron microscopy, powder X-ray diffraction, and N(2) sorption analysis. These structurally ordered mesoporous polymer-silica hybrid nanoparticles were used for the controlled release of membrane-impermeable macromolecules inside eukaryotic cells. The cellular uptake efficiency and biocompatibility of PSN with human cervical cancer cells (HeLa) were investigated. Our results show that the inhibitory concentration (IC(50)) of PSN is very high (>100 μg/mL per million cells), while the median effective concentration for the uptake (EC(50)) of PSN is low (EC(50) = 4.4 μg/mL), indicating that PSNs are fairly biocompatible and easily up-taken in vitro. A membrane-impermeable macromolecule, 40 kDa FITC-Dextran, was loaded into the mesopores of PSNs at low pH. We demonstrated that the PSN material could indeed serve as a transmembrane carrier for the controlled release of FITC-Dextran at the pH level inside live HeLa cells. We believe that further developments of this PSN material will lead to a new generation of nanodevices for intracellular controlled delivery applications.

  4. Properties of nonvolatile and antibacterial bioboard produced from bamboo macromolecules by hot pressing

    Directory of Open Access Journals (Sweden)

    Shengbo Ge

    2018-03-01

    Full Text Available Employing the antibacterial property of industrial bamboo vinegar (IBV and the photocatalytic degradation of TiO2, bamboo macromolecules were pretreated and processed into nonvolatile and antibacterial bio board (NVABB. The NVABB was then analyzed by conducting Fourier-transform infrared spectroscopy, thermogravimetric analysis and differential thermal analysis. Results show that NVABB samples had average density of 0.96 g/cm3, which is appropriate for application. In terms of physical and mechanical properties, the best NVABB sample obtained from IBV, TiO2 and bamboo had an IBV pretreatment time of 10 min, 2% TiO2 and 1% bamboo charcoal. Fourier-transform infrared spectroscopy demonstrated that optimum conditions for hot pressing were a temperature of 170 °C, duration of 15 min and the addition of IBV and TiO2. Thermogravimetric analysis/differential thermal analysis curves suggest that the thermal degradation of NVABB was less than that of bamboo and that hot pressing obviously increased the thermal stability of HDBB samples. Analysis of the antimicrobial effect revealed that IBV pretreatment improves the antibacterial property of NVABB. Keywords: Industrial bamboo vinegar, Nonvolatile and antibacterial bio board, Bamboo macromolecules, Fourier-transform infrared spectroscopy, Thermogravimetric analysis/differential thermal analysis

  5. Distribution volumes of macromolecules in human ovarian and endometrial cancers--effects of extracellular matrix structure.

    Science.gov (United States)

    Haslene-Hox, Hanne; Oveland, Eystein; Woie, Kathrine; Salvesen, Helga B; Tenstad, Olav; Wiig, Helge

    2015-01-01

    Elements of the extracellular matrix (ECM), notably collagen and glucosaminoglycans, will restrict part of the space available for soluble macromolecules simply because the molecules cannot occupy the same space. This phenomenon may influence macromolecular drug uptake. To study the influence of steric and charge effects of the ECM on the distribution volumes of macromolecules in human healthy and malignant gynecologic tissues we used as probes 15 abundant plasma proteins quantified by high-resolution mass spectrometry. The available distribution volume (VA) of albumin was increased in ovarian carcinoma compared with healthy ovarian tissue. Furthermore, VA of plasma proteins between 40 and 190 kDa decreased with size for endometrial carcinoma and healthy ovarian tissue, but was independent of molecular weight for the ovarian carcinomas. An effect of charge on distribution volume was only found in healthy ovaries, which had lower hydration and high collagen content, indicating that a condensed interstitium increases the influence of negative charges. A number of earlier suggested biomarker candidates were detected in increased amounts in malignant tissue, e.g., stathmin and spindlin-1, showing that interstitial fluid, even when unfractionated, can be a valuable source for tissue-specific proteins. We demonstrate that the distribution of abundant plasma proteins in the interstitium can be elucidated by mass spectrometry methods and depends markedly on hydration and ECM structure. Our data can be used in modeling of drug uptake, and give indications on ECM components to be targeted to increase the uptake of macromolecular substances. Copyright © 2015 the American Physiological Society.

  6. A stochastic finite element model for the dynamics of globular macromolecules

    Science.gov (United States)

    Oliver, Robin C.; Read, Daniel J.; Harlen, Oliver G.; Harris, Sarah A.

    2013-04-01

    We describe a novel coarse-grained simulation method for modelling the dynamics of globular macromolecules, such as proteins. The macromolecule is treated as a continuum that is subject to thermal fluctuations. The model includes a non-linear treatment of elasticity and viscosity with thermal noise that is solved using finite element analysis. We have validated the method by demonstrating that the model provides average kinetic and potential energies that are in agreement with the classical equipartition theorem and that the nodal velocities have the correct Gaussian distribution. In addition, we have performed Fourier analysis on the simulation trajectories obtained for a series of linear beams to confirm that the correct average energies are present in the first two Fourier bending modes and that the probability distribution of the amplitudes of the first two Fourier modes match the theoretical results. We demonstrate spatial convergence of the model by showing that the anisotropy of the inertia tensor for a cubic mesh converges as a function of the mesh resolution. We have then used the new modelling method to simulate the thermal fluctuations of a representative protein over 500 ns timescales. Using reasonable parameters for the material properties, we have demonstrated that the overall deformation of the biomolecule is consistent with the results obtained for proteins in general from atomistic molecular dynamics simulations.

  7. Two modified versions of the speciation code PHREEQE for modelling macromolecule-proton/cation interaction

    International Nuclear Information System (INIS)

    Falck, W.E.

    1991-01-01

    There is a growing need to consider the influence of organic macromolecules on the speciation of ions in natural waters. It is recognized that a simple discrete ligand approach to the binding of protons/cations to organic macromolecules is not appropriate to represent heterogeneities of binding site distributions. A more realistic approach has been incorporated into the speciation code PHREEQE which retains the discrete ligand approach but modifies the binding intensities using an electrostatic (surface complexation) model. To allow for different conformations of natural organic material two alternative concepts have been incorporated: it is assumed that (a) the organic molecules form rigid, impenetrable spheres, and (b) the organic molecules form flat surfaces. The former concept will be more appropriate for molecules in the smaller size range, while the latter will be more representative for larger size molecules or organic surface coatings. The theoretical concept is discussed and the relevant changes to the standard PHREEQE code are explained. The modified codes are called PHREEQEO-RS and PHREEQEO-FS for the rigid-sphere and flat-surface models respectively. Improved output facilities for data transfer to other computers, e.g. the Macintosh, are introduced. Examples where the model is tested against literature data are shown and practical problems are discussed. Appendices contain listings of the modified subroutines GAMMA and PTOT, an example input file and an example command procedure to run the codes on VAX computers

  8. Exciton Scattering approach for conjugated macromolecules: from electronic spectra to electron-phonon coupling

    Science.gov (United States)

    Tretiak, Sergei

    2014-03-01

    The exciton scattering (ES) technique is a multiscale approach developed for efficient calculations of excited-state electronic structure and optical spectra in low-dimensional conjugated macromolecules. Within the ES method, the electronic excitations in the molecular structure are attributed to standing waves representing quantum quasi-particles (excitons), which reside on the graph. The exciton propagation on the linear segments is characterized by the exciton dispersion, whereas the exciton scattering on the branching centers is determined by the energy-dependent scattering matrices. Using these ES energetic parameters, the excitation energies are then found by solving a set of generalized ``particle in a box'' problems on the graph that represents the molecule. All parameters can be extracted from quantum-chemical computations of small molecular fragments and tabulated in the ES library for further applications. Subsequently, spectroscopic modeling for any macrostructure within considered molecular family could be performed with negligible numerical effort. The exciton scattering properties of molecular vertices can be further described by tight-binding or equivalently lattice models. The on-site energies and hopping constants are obtained from the exciton dispersion and scattering matrices. Such tight-binding model approach is particularly useful to describe the exciton-phonon coupling, energetic disorder and incoherent energy transfer in large branched conjugated molecules. Overall the ES applications accurately reproduce the optical spectra compared to the reference quantum chemistry results, and make possible to predict spectra of complex macromolecules, where conventional electronic structure calculations are unfeasible.

  9. A dural lymphatic vascular system that drains brain interstitial fluid and macromolecules.

    Science.gov (United States)

    Aspelund, Aleksanteri; Antila, Salli; Proulx, Steven T; Karlsen, Tine Veronica; Karaman, Sinem; Detmar, Michael; Wiig, Helge; Alitalo, Kari

    2015-06-29

    The central nervous system (CNS) is considered an organ devoid of lymphatic vasculature. Yet, part of the cerebrospinal fluid (CSF) drains into the cervical lymph nodes (LNs). The mechanism of CSF entry into the LNs has been unclear. Here we report the surprising finding of a lymphatic vessel network in the dura mater of the mouse brain. We show that dural lymphatic vessels absorb CSF from the adjacent subarachnoid space and brain interstitial fluid (ISF) via the glymphatic system. Dural lymphatic vessels transport fluid into deep cervical LNs (dcLNs) via foramina at the base of the skull. In a transgenic mouse model expressing a VEGF-C/D trap and displaying complete aplasia of the dural lymphatic vessels, macromolecule clearance from the brain was attenuated and transport from the subarachnoid space into dcLNs was abrogated. Surprisingly, brain ISF pressure and water content were unaffected. Overall, these findings indicate that the mechanism of CSF flow into the dcLNs is directly via an adjacent dural lymphatic network, which may be important for the clearance of macromolecules from the brain. Importantly, these results call for a reexamination of the role of the lymphatic system in CNS physiology and disease. © 2015 Aspelund et al.

  10. Flocculation of colloidal clay by bacterial polysaccharides: effect of macromolecule charge and structure.

    Science.gov (United States)

    Labille, J; Thomas, F; Milas, M; Vanhaverbeke, C

    2005-04-01

    The molecular mechanism of montmorillonite flocculation by bacterial polysaccharides was investigated, with special emphasis on the effect of carboxylic charges in the macromolecules on the mechanisms of interaction with the clay surface. An indirect way to quantify the energy of interaction was used, by comparing the flocculation ability of variously acidic polysaccharides. Data on tensile strength of aggregates in diluted suspension were collected by timed size measurements in the domain 0.1-600 microm, using laser diffraction. The flow behavior of settled aggregates was studied by rheology measurements. Flocculation of colloidal clay suspension by polysaccharides requires cancelling of the electrostatic repulsions by salts, which allows approach of clay surfaces close enough to be bridged by adsorbing macromolecules. The amount of acidic charges of the polysaccharides, and especially their location in the molecular structure, governs the bridging mechanism and the resulting tensile strength of the aggregates. The exposure of carboxylate groups located on side chains strongly promotes flocculation. In turn, charges located on the backbone of the polysaccharide are less accessible to interaction, and the flocculation ability of such polysaccharides is lowered. Measurements at different pH indicate that adsorption of acidic polysaccharides occurs via electrostatic interactions on the amphoteric edge surface of clay platelets, whereas neutral polysaccharides rather adsorb via weak interactions. Increased tensile strength in diluted aggregates due to strong surface interactions results in proportionally increased viscosity of the concentrated aggregates.

  11. Multifunctional gadolinium-based dendritic macromolecules as liver targeting imaging probes.

    Science.gov (United States)

    Luo, Kui; Liu, Gang; He, Bin; Wu, Yao; Gong, Qingyong; Song, Bin; Ai, Hua; Gu, Zhongwei

    2011-04-01

    The quest for highly efficient and safe contrast agents has become the key factor for successful application of magnetic resonance imaging (MRI). The gadolinium (Gd) based dendritic macromolecules, with precise and tunable nanoscopic sizes, are excellent candidates as multivalent MRI probes. In this paper, a novel series of Gd-based multifunctional peptide dendritic probes (generation 2, 3, and 4) possessing highly controlled structures and single molecular weight were designed and prepared as liver MRI probes. These macromolecular Gd-ligand agents exhibited up to 3-fold increase in T(1) relaxivity comparing to Gd-DTPA complexes. No obvious in vitro cytotoxicity was observed from the measured concentrations. These dendritic probes were further functionalized with multiple galactosyl moieties and led to much higher cell uptake in vitro as demonstrated in T(1)-weighted scans. During in vivo animal studies, the probes provided better signal intensity (SI) enhancement in mouse liver, especially at 60 min post-injection, with the most efficient enhancement from the galactosyl moiety decorated third generation dendrimer. The imaging results were verified with analysis of Gd content in liver tissues. The design strategy of multifunctional Gd-ligand peptide dendritic macromolecules in this study may be used for developing other sensitive MRI probes with targeting capability. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Multiband superconductivity in heavy fermion compound CePt3Si without inversion symmetry. An NMR study on a high-quality single crystal

    International Nuclear Information System (INIS)

    Mukuda, Hidekazu; Nishide, Sachihiro; Harada, Atsushi

    2009-01-01

    We report on novel superconducting characteristics of the heavy fermion (HF) superconductor CePt 3 Si without inversion symmetry through 195 Pt-NMR study on a single crystal with T c =0.46 K that is lower than T c - 0.75 K for polycrystals. We show that the intrinsic superconducting characteristics inherent to CePt 3 Si can be understood in terms of the unconventional strong-coupling state with a line-node gap below T c =0.46 K. The mystery about the sample dependence of T c is explained by the fact that more or less polycrystals and single crystals inevitably contain some disordered domains, which exhibit a conventional BCS s-wave superconductivity (SC) below 0.8 K. In contrast, the Neel temperature T N - 2.2 K is present regardless of the quality of samples, revealing that the Fermi surface responsible for SC differ from that for the antiferromagnetic order. These unusual characteristics of CePt 3 Si can be also described by a multiband model; in the homogeneous domains, the coherent HF bands are responsible for the unconventional SC, whereas in the disordered domains the conduction bands existing commonly in LaPt 3 Si may be responsible for the conventional s-wave SC. We remark that some impurity scatterings in the disordered domains break up the 4f-electrons-derived coherent bands but not others. In this context, the small peak in 1/T 1 just below T c reported before [Yogi et al. (2004)] is not due to a two-component order parameter composed of spin-singlet and spin-triplet Cooper pairing states, but due to the contamination of the disorder domains which are in the s-wave SC state. (author)

  13. Self-Organized Crystallization Patterns from Evaporating Droplets of Common Wheat Grain Leakages as a Potential Tool for Quality Analysis

    Directory of Open Access Journals (Sweden)

    Maria Olga Kokornaczyk

    2011-01-01

    Full Text Available We studied the evaporation-induced pattern formation in droplets of common wheat kernel leakages prepared out of ancient and modern wheat cultivars as a possible tool for wheat quality analysis. The experiments showed that the substances which passed into the water during the soaking of the kernels created crystalline structures with different degrees of complexity while the droplets were evaporating. The forms ranged from spots and simple structures with single ramifications, through dendrites, up to highly organized hexagonal shapes and fractal-like structures. The patterns were observed and photographed using dark field microscopy in small magnifications. The evaluation of the patterns was performed both visually and by means of the fractal dimension analysis. From the results, it can be inferred that the wheat cultivars differed in their pattern-forming capacities. Two of the analyzed wheat cultivars showed poor pattern formation, whereas another two created well-formed and complex patterns. Additionally, the wheat cultivars were analyzed for their vigor by means of the germination test and measurement of the electrical conductivity of the grain leakages. The results showed that the more vigorous cultivars also created more complex patterns, whereas the weaker cultivars created predominantly poor forms. This observation suggests a correlation between the wheat seed quality and droplet evaporation patterns.

  14. Quality

    International Nuclear Information System (INIS)

    Burnett, N.; Jeffries, J.; Mach, J.; Robson, M.; Pajot, D.; Harrigan, J.; Lebsack, T.; Mullen, D.; Rat, F.; Theys, P.

    1993-01-01

    What is quality? How do you achieve it? How do you keep it once you have got it. The answer for industry at large is the three-step hierarchy of quality control, quality assurance and Total quality Management. An overview is given of the history of quality movement, illustrated with examples from Schlumberger operations, as well as the oil industry's approach to quality. An introduction of the Schlumberger's quality-associated ClientLink program is presented. 15 figs., 4 ills., 16 refs

  15. The utility of comparative models and the local model quality for protein crystal structure determination by Molecular Replacement

    Directory of Open Access Journals (Sweden)

    Pawlowski Marcin

    2012-11-01

    Full Text Available Abstract Background Computational models of protein structures were proved to be useful as search models in Molecular Replacement (MR, a common method to solve the phase problem faced by macromolecular crystallography. The success of MR depends on the accuracy of a search model. Unfortunately, this parameter remains unknown until the final structure of the target protein is determined. During the last few years, several Model Quality Assessment Programs (MQAPs that predict the local accuracy of theoretical models have been developed. In this article, we analyze whether the application of MQAPs improves the utility of theoretical models in MR. Results For our dataset of 615 search models, the real local accuracy of a model increases the MR success ratio by 101% compared to corresponding polyalanine templates. On the contrary, when local model quality is not utilized in MR, the computational models solved only 4.5% more MR searches than polyalanine templates. For the same dataset of the 615 models, a workflow combining MR with predicted local accuracy of a model found 45% more correct solution than polyalanine templates. To predict such accuracy MetaMQAPclust, a “clustering MQAP” was used. Conclusions Using comparative models only marginally increases the MR success ratio in comparison to polyalanine structures of templates. However, the situation changes dramatically once comparative models are used together with their predicted local accuracy. A new functionality was added to the GeneSilico Fold Prediction Metaserver in order to build models that are more useful for MR searches. Additionally, we have developed a simple method, AmIgoMR (Am I good for MR?, to predict if an MR search with a template-based model for a given template is likely to find the correct solution.

  16. Monomial Crystals and Partition Crystals

    Science.gov (United States)

    Tingley, Peter

    2010-04-01

    Recently Fayers introduced a large family of combinatorial realizations of the fundamental crystal B(Λ0) for ^sln, where the vertices are indexed by certain partitions. He showed that special cases of this construction agree with the Misra-Miwa realization and with Berg's ladder crystal. Here we show that another special case is naturally isomorphic to a realization using Nakajima's monomial crystal.

  17. High quality Y-type hexaferrite thick films for microwave applications by an economical and environmentally benign crystal growth technique

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Bolin; Chen, Yajie, E-mail: y.chen@neu.edu; Gillette, Scott; Su, Zhijuan; Harris, Vincent G. [Center for Microwave Magnetic Materials and Integrated Circuits and Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts 02115 (United States); Wolf, Jason; McHenry, Michael E. [Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)

    2014-02-17

    Thick barium hexaferrite Ba{sub 2}Zn{sub 2}Fe{sub 12}O{sub 22} (i.e., Zn{sub 2}Y) films having thicknesses of ∼100 μm were epitaxially grown on MgO (111) substrates using an environmentally benign ferrite-salt mixture by vaporizing the salt. X-ray diffraction pole figure analyses showed (00l) crystallographic alignment with little in plane dispersion confirming epitaxial growth. Saturation magnetization, 4πM{sub s}, was measured for as-grown films to be 2.51 ± 0.1 kG with an out of plane magnetic anisotropy field H{sub A} of 8.9 ± 0.1 kOe. Ferromagnetic resonance linewidth, as the peak-to-peak power absorption derivative at 9.6 GHz, was measured to be 62 Oe. These properties demonstrate a rapid, convenient, cost-effective, and nontoxic method of growing high quality thick crystalline ferrite films which could be used widely for microwave device applications.

  18. Tension-controlled single-crystallization of copper foils for roll-to-roll synthesis of high-quality graphene films

    Science.gov (United States)

    Jo, Insu; Park, Subeom; Kim, Dongjin; San Moon, Jin; Park, Won Bae; Kim, Tae Hyeong; Hyoun Kang, Jin; Lee, Wonbae; Kim, Youngsoo; Lee, Dong Nyung; Cho, Sung-Pyo; Choi, Hyunchul; Kang, Inbyeong; Park, Jong Hyun; Lee, Jeong Soo; Hong, Byung Hee

    2018-04-01

    It has been known that the crystalline orientation of Cu substrates plays a crucial role in chemical vapor deposition (CVD) synthesis of high-quality graphene. In particular, Cu (1 1 1) surface showing the minimum lattice mismatch with graphene is expected to provide an ideal catalytic reactivity that can minimize the formation of defects, which also induces larger single-crystalline domain sizes of graphene. Usually, the Cu (1 1 1) substrates can be epitaxially grown on single-crystalline inorganic substrates or can be recrystallized by annealing for more than 12 h, which limits the cost and time-effective synthesis of graphene. Here, we demonstrate a new method to optimize the crystalline orientations of vertically suspended Cu foils by tension control during graphene growth, resulting in large-area recrystallization into Cu (1 1 1) surface as the applied tension activates the grain boundary energy of Cu and promotes its abnormal grain growth to single crystals. In addition, we found a clue that the formation of graphene cooperatively assists the recrystallization into Cu (1 1 1) by minimizing the surface energy of Cu. The domain sizes and charge carrier mobility of graphene grown on the single-crystalline Cu (1 1 1) are 5 times and ~50% increased, respectively, in comparison with those of graphene from Cu (1 0 0), indicating that the less lattice mismatch and the lower interaction energy between Cu (1 1 1) and graphene allows the growth of larger single-crystalline graphene with higher charge carrier mobility. Thus, we believe that our finding provides a crucial idea to design a roll-to-roll (R2R) graphene synthesis system where the tension control is inevitably involved, which would be of great importance for the continuous production of high-quality graphene in the future.

  19. Estimating absolute configurational entropies of macromolecules: the minimally coupled subspace approach.

    Directory of Open Access Journals (Sweden)

    Ulf Hensen

    Full Text Available We develop a general minimally coupled subspace approach (MCSA to compute absolute entropies of macromolecules, such as proteins, from computer generated canonical ensembles. Our approach overcomes limitations of current estimates such as the quasi-harmonic approximation which neglects non-linear and higher-order correlations as well as multi-minima characteristics of protein energy landscapes. Here, Full Correlation Analysis, adaptive kernel density estimation, and mutual information expansions are combined and high accuracy is demonstrated for a number of test systems ranging from alkanes to a 14 residue peptide. We further computed the configurational entropy for the full 67-residue cofactor of the TATA box binding protein illustrating that MCSA yields improved results also for large macromolecular systems.

  20. A Biology Laboratory Exercise Using Macromolecule Assays to Distinguish Four Types of Milk

    Directory of Open Access Journals (Sweden)

    Charlotte W. Pratt

    2011-03-01

    Full Text Available One of the drawbacks of cookbook-style laboratory exercises for General Biology courses is that students are not challenged to develop skills in scientific reasoning, such as formulating hypotheses and designing and carrying out experiments. Several traditional laboratory curricula include exercises involving semi-quantitative colorimetric assays to detect proteins (biuret test, reducing sugars (Benedict’s test, starch (Lugol’s test, and lipids (Sudan red test in a variety of easily prepared solutions (glucose, albumin, glycine, etc. and familiar food items (lemon juice, cornstarch, egg white, etc.. An extension of this lab exercise was developed to allow students to use their knowledge of the macromolecule assays to design an experiment to distinguish four types of “milk”: whole milk, skim milk, cream, and soy milk (rice milk or almond milk could also be included.

  1. NATO Advanced Research Workshop on Nuclear Magnetic Resonance of Paramagnetic Macromolecules

    CERN Document Server

    1995-01-01

    Since A. Kowalsky's first report of the spectrum of cytochrome c in 1965, interest in the detection, assignment and interpretation of paramagnetic molecules has surged, especially in the last decade. Two classes of systems have played a key role in the development of the field: heme proteins and iron-sulfur proteins. These two systems are unique in many respects, one of which is that they contain well-defined chromophores, each of which can be studied in detail outside the protein matrix. They are the most successfully studied macromolecules, and the first eight and last six of the seventeen contributions to this book deal with heme and/or iron-sulfur proteins. The middle three chapters survey the progress on, and significant promise of, more difficult systems which do not possess a chromophore, but which have nevertheless yielded remarkable insights into their structure.

  2. Synthesis of macromolecules by the epithelial surfaces of Schistosoma mansoni: an autoradiographic study

    International Nuclear Information System (INIS)

    Wilson, R.A.; Barnes, P.E.

    1979-01-01

    The use of tritiated leucine as a marker for protein synthesis and of tritiated glucosamine as a marker for polysaccharide/glycoprotein synthesis, is described. Adult worms were pulse-labelled by incubation in medium containing the substrate. Labelled worms were then incubated in chase medium, without labelled substrate, for varying lengths of time before fixation. The distribution of label which had been incorporated into macromolecules in the worm tissues, was examined by light and electron microscope autoradiography. The results suggest that the bulk of worm secretions have a rapid turnover with a half-life of a few hours. Against this background of rapid mass secretion, a slower process of membrane turnover would be difficult to detect and quantitatively small. (author)

  3. Conformations of polyelectrolyte macromolecules with different charge density in solutions of different ionic strengths

    International Nuclear Information System (INIS)

    Dommes, O A; Okatova, O V; Pavlov, G M

    2016-01-01

    Studies of charged polymer chains are interesting in both fundamental and applied aspects. Especially, polyelectrolytes attract huge attention of researchers due to their ability to form interpolymer complexes with synthetic and biopolymers. The study was carried out on the fractions of hydrophilic copolymers of N-methyl-N-vinyl acetamide and N-methyl-N-vinyl amine hydrochloride of different degrees of polymerization and of different charge density using methods of molecular hydrodynamics. Hydrodynamic and conformational characteristics as well as molar masses of isolated molecules were estimated. In addition, the intrinsic viscosity of fractions was studied at the extreme ionic strengths - in distilled water (∼10 -6 M) and in 6M NaCl. Scaling relations for intrinsic viscosity, sedimentation and translational diffusion coefficients with molar mass were obtained. Conformational behavior of macromolecules with different linear charge density was compared. (paper)

  4. Load-release of small and macromolecules from elastomers with reversible gyroid mesoporosity

    DEFF Research Database (Denmark)

    Guo, Fengxiao; Schulte, Lars; Ndoni, Sokol

    2012-01-01

    . However, in the gel state in the presence of a good solvent the swollen matrix did show a nanoporous structure originated from the gyroid block copolymer precursor. Nanopores can be opened or closed depending on the presence or absence of a solvent. Macromolecules like PEG of different molecular weights......A collapsed elastomeric matrix of lightly cross-linked 1,2-polybutadiene (1,2-PB) was prepared from a self-assembled 1,2-polybutadiene-b- polydimethylsiloxane (1,2-PB-b-PDMS) of gyroid morphology after the removal of the PDMS block. No mesoporosity could be observed in the material in the dry state...... or small molecules like the surfactant SDS were loaded into the opened nanoporous matrix in the presence of a solvent and remained trapped. The loaded molecules could be released again in the presence of a solvent. The load and release of the molecules in deuterated form were monitored by in situ time...

  5. Synthesis and biological incorporatin of icons into macromolecules for NMR study

    International Nuclear Information System (INIS)

    Grant, D.M.

    1976-02-01

    Work has proceeded successfully to synthesize novel 13 C-labeled materials for incorporation into macromolecules. Gram quantities of C-4 labeled uracil have been synthesized and incorporated, by means of a mutant bacterial strain into t-RNA. The t-RNA has been isolated, purified, and carbon-13 T 1 studies have begun. A modern, well equipped biochemistry laboratory has become functional during the present contract period. Good progress has been made on nonenzymatic reactions of pyridoxal-5'-phosphate with selected amino actions. This effort has successfully elucidated many reaction intermediates and products. In addition, 13 C containing haptens have been synthesized and screening tests have now begun on rabbits to verify the specificity of antibodies for two haptens

  6. Sensitivity enhancement in NMR of macromolecules by application of optimal control theory

    International Nuclear Information System (INIS)

    Frueh, Dominique P.; Ito, Takuhiro; Li, J.-S.; Wagner, Gerhard; Glaser, Steffen J.; Khaneja, Navin

    2005-01-01

    NMR of macromolecules is limited by large transverse relaxation rates. In practice, this results in low efficiency of coherence transfer steps in multidimensional NMR experiments, leading to poor sensitivity and long acquisition times. The efficiency of coherence transfer can be maximized by design of relaxation optimized pulse sequences using tools from optimal control theory. In this paper, we demonstrate that this approach can be adopted for studies of large biological systems, such as the 800 kDa chaperone GroEL. For this system, the 1 H- 15 N coherence transfer module presented here yields an average sensitivity enhancement of 20-25% for cross-correlated relaxation induced polarization transfer (CRIPT) experiments

  7. Permeation enhancing polymers in oral delivery of hydrophilic macromolecules: thiomer/GSH systems.

    Science.gov (United States)

    Bernkop-Schnürch, A; Kast, C E; Guggi, D

    2003-12-05

    Thiolated polymers (= thiomers) in combination with reduced glutathione (GSH) were shown to improve the uptake of hydrophilic macromolecules from the GI tract. The mechanism responsible for this permeation enhancing effect seems to be based on the thiol groups of the polymer. These groups inhibit protein tyrosine phosphatase, being involved in the closing process of tight junctions, via a GSH-mediated mechanism. The strong permeation enhancing effect of various thiomer/GSH systems such as poly(acrylic acid)-cysteine/GSH or chitosan-4-thio-butylamidine (chitosan-TBA)/GSH could be shown via permeation studies on freshly excised intestinal mucosa in Ussing-type chambers. Furthermore, the efficacy of the system was also shown in vivo. By utilizing poly(acrylic acid)-cysteine/GSH as carrier matrix, an absolute oral bioavailability for low molecular weight heparin of 19.9 +/- 9.3% and a pharmacological efficacy--calculated on the basis of the areas under the reduction in serum glucose levels of the oral formulation versus subcutaneous (s.c.) injection-for orally given insulin of 7% could be achieved. The incorporation of salmon calcitonin in chitosan-TBA/GSH led on the other hand to a pharmacological efficacy based on the areas under the reduction in plasma calcium levels of the oral thiomer formulation versus intravenous (i.v.) injection of 1.3%. Because of this high efficacy (i), the possibility to combine thiomer/GSH systems with additional low molecular weight permeation enhancers acting in other ways (ii) and minimal toxicological risks as these polymers are not absorbed from the GI tract (iii), thiolated polymers represent a promising novel tool for the oral administration of hydrophilic macromolecules.

  8. A mathematical model for filtration and macromolecule transport across capillary walls.

    Science.gov (United States)

    Facchini, L; Bellin, A; Toro, E F

    2014-07-01

    Metabolic substrates, such as oxygen and glucose, are rapidly delivered to the cells of large organisms through filtration across microvessels walls. Modelling this important process is complicated by the strong coupling between flow and transport equations, which are linked through the osmotic pressure induced by the colloidal plasma proteins. The microvessel wall is a composite media with the internal glycocalyx layer exerting a strong sieving effect on macromolecules, with respect to the external layer composed by the endothelial cells. The physiological structure of the microvessel is represented as the superimposition of two membranes with different properties; the inner membrane represents the glycocalyx, while the outer membrane represents the surrounding endothelial cells. Application of the mass conservation principle and thermodynamic considerations lead to a model composed of two coupled second-order ordinary differential equations for the hydrostatic and osmotic pressures, one, expressing volumetric mass conservation and the other, which is non-linear in the unknown osmotic pressure, expressing macromolecules mass conservation. Despite the complexity of the system, the assumption that the properties of the layers are piece-wise constant allows us to obtain analytical solutions for the two pressures. This solution is in agreement with experimental observations, which contrary to common belief, show that flow reversal cannot occur in steady-state conditions unless the hydrostatic pressure in the lumen drops below physiologically plausible values. The observed variations of the volumetric flux and the solute mass flux in case of a significant reduction of the hydrostatic pressure at the lumen are in qualitative agreement with observed variations during detailed experiments reported in the literature. On the other hand, homogenising the microvessel wall into a single-layer membrane with equivalent properties leads to a very different distribution of

  9. Exciton scattering approach for optical spectra calculations in branched conjugated macromolecules

    International Nuclear Information System (INIS)

    Li, Hao; Wu, Chao; Malinin, Sergey V.; Tretiak, Sergei; Chernyak, Vladimir Y.

    2016-01-01

    The exciton scattering (ES) technique is a multiscale approach based on the concept of a particle in a box and developed for efficient calculations of excited-state electronic structure and optical spectra in low-dimensional conjugated macromolecules. Within the ES method, electronic excitations in molecular structure are attributed to standing waves representing quantum quasi-particles (excitons), which reside on the graph whose edges and nodes stand for the molecular linear segments and vertices, respectively. Exciton propagation on the linear segments is characterized by the exciton dispersion, whereas exciton scattering at the branching centers is determined by the energy-dependent scattering matrices. Using these ES energetic parameters, the excitation energies are then found by solving a set of generalized “particle in a box” problems on the graph that represents the molecule. Similarly, unique energy-dependent ES dipolar parameters permit calculations of the corresponding oscillator strengths, thus, completing optical spectra modeling. Both the energetic and dipolar parameters can be extracted from quantum-chemical computations in small molecular fragments and tabulated in the ES library for further applications. Subsequently, spectroscopic modeling for any macrostructure within a considered molecular family could be performed with negligible numerical effort. We demonstrate the ES method application to molecular families of branched conjugated phenylacetylenes and ladder poly-para-phenylenes, as well as structures with electron donor and acceptor chemical substituents. Time-dependent density functional theory (TD-DFT) is used as a reference model for electronic structure. The ES calculations accurately reproduce the optical spectra compared to the reference quantum chemistry results, and make possible to predict spectra of complex macromolecules, where conventional electronic structure calculations are unfeasible.

  10. Exciton scattering approach for optical spectra calculations in branched conjugated macromolecules

    Science.gov (United States)

    Li, Hao; Wu, Chao; Malinin, Sergey V.; Tretiak, Sergei; Chernyak, Vladimir Y.

    2016-12-01

    The exciton scattering (ES) technique is a multiscale approach based on the concept of a particle in a box and developed for efficient calculations of excited-state electronic structure and optical spectra in low-dimensional conjugated macromolecules. Within the ES method, electronic excitations in molecular structure are attributed to standing waves representing quantum quasi-particles (excitons), which reside on the graph whose edges and nodes stand for the molecular linear segments and vertices, respectively. Exciton propagation on the linear segments is characterized by the exciton dispersion, whereas exciton scattering at the branching centers is determined by the energy-dependent scattering matrices. Using these ES energetic parameters, the excitation energies are then found by solving a set of generalized "particle in a box" problems on the graph that represents the molecule. Similarly, unique energy-dependent ES dipolar parameters permit calculations of the corresponding oscillator strengths, thus, completing optical spectra modeling. Both the energetic and dipolar parameters can be extracted from quantum-chemical computations in small molecular fragments and tabulated in the ES library for further applications. Subsequently, spectroscopic modeling for any macrostructure within a considered molecular family could be performed with negligible numerical effort. We demonstrate the ES method application to molecular families of branched conjugated phenylacetylenes and ladder poly-para-phenylenes, as well as structures with electron donor and acceptor chemical substituents. Time-dependent density functional theory (TD-DFT) is used as a reference model for electronic structure. The ES calculations accurately reproduce the optical spectra compared to the reference quantum chemistry results, and make possible to predict spectra of complex macromolecules, where conventional electronic structure calculations are unfeasible.

  11. Exciton scattering approach for optical spectra calculations in branched conjugated macromolecules

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hao [Department of Chemistry, University of Houston, Houston, TX 77204 (United States); Wu, Chao [Electronic Structure Lab, Center of Microscopic Theory and Simulation, Frontier Institute of Science and Technology, Xian Jiaotong University, Xian 710054 (China); Malinin, Sergey V. [Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI 48202 (United States); Tretiak, Sergei, E-mail: serg@lanl.gov [Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Chernyak, Vladimir Y., E-mail: chernyak@chem.wayne.edu [Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI 48202 (United States)

    2016-12-20

    The exciton scattering (ES) technique is a multiscale approach based on the concept of a particle in a box and developed for efficient calculations of excited-state electronic structure and optical spectra in low-dimensional conjugated macromolecules. Within the ES method, electronic excitations in molecular structure are attributed to standing waves representing quantum quasi-particles (excitons), which reside on the graph whose edges and nodes stand for the molecular linear segments and vertices, respectively. Exciton propagation on the linear segments is characterized by the exciton dispersion, whereas exciton scattering at the branching centers is determined by the energy-dependent scattering matrices. Using these ES energetic parameters, the excitation energies are then found by solving a set of generalized “particle in a box” problems on the graph that represents the molecule. Similarly, unique energy-dependent ES dipolar parameters permit calculations of the corresponding oscillator strengths, thus, completing optical spectra modeling. Both the energetic and dipolar parameters can be extracted from quantum-chemical computations in small molecular fragments and tabulated in the ES library for further applications. Subsequently, spectroscopic modeling for any macrostructure within a considered molecular family could be performed with negligible numerical effort. We demonstrate the ES method application to molecular families of branched conjugated phenylacetylenes and ladder poly-para-phenylenes, as well as structures with electron donor and acceptor chemical substituents. Time-dependent density functional theory (TD-DFT) is used as a reference model for electronic structure. The ES calculations accurately reproduce the optical spectra compared to the reference quantum chemistry results, and make possible to predict spectra of complex macromolecules, where conventional electronic structure calculations are unfeasible.

  12. A Mo-anode-based in-house source for small-angle X-ray scattering measurements of biological macromolecules

    Energy Technology Data Exchange (ETDEWEB)

    Bruetzel, Linda K.; Fischer, Stefan; Salditt, Annalena; Sedlak, Steffen M.; Nickel, Bert; Lipfert, Jan, E-mail: Jan.Lipfert@lmu.de [Department of Physics, Nanosystems Initiative Munich, and Center for Nanoscience, Ludwig-Maximilians-University Munich, Amalienstr. 54, 80799 Munich, Germany and Geschwister-Scholl Platz 1, 80539 Munich (Germany)

    2016-02-15

    We demonstrate the use of a molybdenum-anode-based in-house small-angle X-ray scattering (SAXS) setup to study biological macromolecules in solution. Our system consists of a microfocus X-ray tube delivering a highly collimated flux of 2.5 × 10{sup 6} photons/s at a beam size of 1.2 × 1.2 mm{sup 2} at the collimation path exit and a maximum beam divergence of 0.16 mrad. The resulting observable scattering vectors q are in the range of 0.38 Å{sup −1} down to 0.009 Å{sup −1} in SAXS configuration and of 0.26 Å{sup −1} up to 5.7 Å{sup −1} in wide-angle X-ray scattering (WAXS) mode. To determine the capabilities of the instrument, we collected SAXS data on weakly scattering biological macromolecules including proteins and a nucleic acid sample with molecular weights varying from ∼12 to 69 kDa and concentrations of 1.5–24 mg/ml. The measured scattering data display a high signal-to-noise ratio up to q-values of ∼0.2 Å{sup −1} allowing for an accurate structural characterization of the samples. Moreover, the in-house source data are of sufficient quality to perform ab initio 3D structure reconstructions that are in excellent agreement with the available crystallographic structures. In addition, measurements for the detergent decyl-maltoside show that the setup can be used to determine the size, shape, and interactions (as characterized by the second virial coefficient) of detergent micelles. This demonstrates that the use of a Mo-anode based in-house source is sufficient to determine basic geometric parameters and 3D shapes of biomolecules and presents a viable alternative to valuable beam time at third generation synchrotron sources.

  13. Crystallization mechanisms of acicular crystals

    Science.gov (United States)

    Puel, François; Verdurand, Elodie; Taulelle, Pascal; Bebon, Christine; Colson, Didier; Klein, Jean-Paul; Veesler, Stéphane

    2008-01-01

    In this contribution, we present an experimental investigation of the growth of four different organic molecules produced at industrial scale with a view to understand the crystallization mechanism of acicular or needle-like crystals. For all organic crystals studied in this article, layer-by-layer growth of the lateral faces is very slow and clear, as soon as the supersaturation is high enough, there is competition between growth and surface-activated secondary nucleation. This gives rise to pseudo-twinned crystals composed of several needle individuals aligned along a crystallographic axis; this is explained by regular over- and inter-growths as in the case of twinning. And when supersaturation is even higher, nucleation is fast and random. In an industrial continuous crystallization, the rapid growth of needle-like crystals is to be avoided as it leads to fragile crystals or needles, which can be partly broken or totally detached from the parent crystals especially along structural anisotropic axis corresponding to weaker chemical bonds, thus leading to slower growing faces. When an activated mechanism is involved such as a secondary surface nucleation, it is no longer possible to obtain a steady state. Therefore, the crystal number, size and habit vary significantly with time, leading to troubles in the downstream processing operations and to modifications of the final solid-specific properties. These results provide valuable information on the unique crystallization mechanisms of acicular crystals, and show that it is important to know these threshold and critical values when running a crystallizer in order to obtain easy-to-handle crystals.

  14. Macrodefect-free, large, and thick GaN bulk crystals for high-quality 2–6 in. GaN substrates by hydride vapor phase epitaxy with hardness control

    Science.gov (United States)

    Fujikura, Hajime; Konno, Taichiro; Suzuki, Takayuki; Kitamura, Toshio; Fujimoto, Tetsuji; Yoshida, Takehiro

    2018-06-01

    On the basis of a novel crystal hardness control, we successfully realized macrodefect-free, large (2–6 in.) and thick +c-oriented GaN bulk crystals by hydride vapor phase epitaxy. Without the hardness control, the introduction of macrodefects including inversion domains and/or basal-plane dislocations seemed to be indispensable to avoid crystal fracture in GaN growth with millimeter thickness. However, the presence of these macrodefects tended to limit the applicability of the GaN substrate to practical devices. The present technology markedly increased the GaN crystal hardness from below 20 to 22 GPa, thus increasing the available growth thickness from below 1 mm to over 6 mm even without macrodefect introduction. The 2 and 4 in. GaN wafers fabricated from these crystals had extremely low dislocation densities in the low- to mid-105 cm‑2 range and low off-angle variations (2 in.: <0.1° 4 in.: ∼0.2°). The realization of such high-quality 6 in. wafers is also expected.

  15. 3D DNA Origami Crystals.

    Science.gov (United States)

    Zhang, Tao; Hartl, Caroline; Frank, Kilian; Heuer-Jungemann, Amelie; Fischer, Stefan; Nickels, Philipp C; Nickel, Bert; Liedl, Tim

    2018-05-18

    3D crystals assembled entirely from DNA provide a route to design materials on a molecular level and to arrange guest particles in predefined lattices. This requires design schemes that provide high rigidity and sufficiently large open guest space. A DNA-origami-based "tensegrity triangle" structure that assembles into a 3D rhombohedral crystalline lattice with an open structure in which 90% of the volume is empty space is presented here. Site-specific placement of gold nanoparticles within the lattice demonstrates that these crystals are spacious enough to efficiently host 20 nm particles in a cavity size of 1.83 × 10 5 nm 3 , which would also suffice to accommodate ribosome-sized macromolecules. The accurate assembly of the DNA origami lattice itself, as well as the precise incorporation of gold particles, is validated by electron microscopy and small-angle X-ray scattering experiments. The results show that it is possible to create DNA building blocks that assemble into lattices with customized geometry. Site-specific hosting of nano objects in the optically transparent DNA lattice sets the stage for metamaterial and structural biology applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Spatial and temporal variations in bacterial macromolecule labeling with [methyl-3H]thymidine in a hypertrophic lake

    International Nuclear Information System (INIS)

    Robarts, R.D.; Wicks, R.J.; Sephton, L.M.

    1986-01-01

    The incorporation of [methyl- 3 H]thymidine into three macromolecular fractions, designated as DNA, RNA, and protein, by bacteria from Hartbeespoort Dam, South Africa, was measured over 1 year by acid-base hydrolysis procedures. Samples were collected at 10 m, which was at least 5 m beneath the euphotic zone. On four occasions, samples were concurrently collected at the surface. Approximately 80% of the label was incorporated into bacterial DNA in surface samples. At 10 m, total incorporation of label into bacterial macromolecules was correlated to bacterial utilization of glucose. The labeling of DNA, which ranged between 0 and 78% of total macromolecule incorporation, was inversely related to glucose uptake, total thymidine incorporation, and euphotic zone algal production. With decreased DNA labeling, increasing proportions of label were found in the RNA fraction and proteins. Enzymatic digestion followed by chromatographic separation of macromolecule fragments indicated that DNA and proteins were labeled while RNA was not. The RNA fraction may represent labeled lipids or other macromolecules or both. The data demonstrated a close coupling between phytoplankton production and heterotrophic bacterial activity in this hypertrophic lake but also confirmed the need for the routine extraction and purification of DNA during [methyl- 3 H]thymidine studies of aquatic bacterial production

  17. Novel tendencies in developing small-angle neutron scattering methods for studying the structure of biological macromolecules

    International Nuclear Information System (INIS)

    Serdyuk, I.

    1995-01-01

    In recent 20 years thermal neutron scattering has been acknowledged an important instrument for structural studies in molecular biology. The methods of neutron diffraction of high resolution, which are not discussed in this paper, have already permitted to obtain a detailed representation of the course of proteolytic reactions and have arisen a number of new problems connected with the localization of water molecules and the H-D exchange. The methods of low resolution widely used due to a relative simplicity of the experiment have been successfully applied for both solving structural problems per se and investigating the changes in the structure when macromolecules perform their biological functions. The most promising are novel experimental approaches: the triple isotopic substitution method and the method of spin dynamic polarization. These methods ensure solving structural problems at a higher resolution than the dimensions of the macromolecules studied. Installation of new experimental instruments makes neutron measurements more accessible, and development of direct methods for interpretation of experimental data using the apparatus of spherical harmonics opens new possibilities for small-angle neutron scattering making it a necessary element for interpretation of diffraction data of monocrystals of intricate biological macromolecules. The paper presents a brief account of the tendencies in theoretical development and practical use of small-angle scattering for studying biological macromolecules. Special attention is given to the studies carried out in the Laboratory of Neutron Physics on a unique pulse IBR-2 reactor. (author) 14 refs

  18. Hydroxycinnamic acids are ester-linked directly to glucosyl moieties within the lignan macromolecule from flaxseed hulls

    NARCIS (Netherlands)

    Struijs, K.; Vincken, J.P.; Verhoef, R.P.; Voragen, A.G.J.; Gruppen, H.

    2008-01-01

    In flaxseed hulls, lignans are present in an oligomeric structure. Secoisolariciresinol diglucoside (SDG), ester-linked to hydroxy-methyl-glutaric acid (HMGA), forms the backbone of this lignan macromolecule. The hydroxycinnamic acids p-coumaric acid glucoside (CouAG) and ferulic acid glucoside

  19. Conference on chemical evolution and the origin of life: Self-organization of the macromolecules of life

    International Nuclear Information System (INIS)

    1993-10-01

    The formation of biomolecules was a necessary step in the evolution of life on earth. This interdisciplinary conference emphasized the role of replication in processes of self-organization of biological macromolecules. The present document contains abstracts of the 26 contributions to the conference on chemical evolution. The individual contributions have been indexed separately for the database

  20. Nanoparticles Doped, Photorefractive Liquid Crystals

    National Research Council Canada - National Science Library

    Kaczmarek, Malgosia

    2005-01-01

    ...: The main objectives of this exploratory, short project will concern the study of the quality of liquid crystal cells with diluted suspensions of ferroelectric nanoparticles and their photorefractive properties...

  1. Macromolecular competition titration method accessing thermodynamics of the unmodified macromolecule-ligand interactions through spectroscopic titrations of fluorescent analogs.

    Science.gov (United States)

    Bujalowski, Wlodzimierz; Jezewska, Maria J

    2011-01-01

    Analysis of thermodynamically rigorous binding isotherms provides fundamental information about the energetics of the ligand-macromolecule interactions and often an invaluable insight about the structure of the formed complexes. The Macromolecular Competition Titration (MCT) method enables one to quantitatively obtain interaction parameters of protein-nucleic acid interactions, which may not be available by other methods, particularly for the unmodified long polymer lattices and specific nucleic acid substrates, if the binding is not accompanied by adequate spectroscopic signal changes. The method can be applied using different fluorescent nucleic acids or fluorophores, although the etheno-derivatives of nucleic acid are especially suitable as they are relatively easy to prepare, have significant blue fluorescence, their excitation band lies far from the protein absorption spectrum, and the modification eliminates the possibility of base pairing with other nucleic acids. The MCT method is not limited to the specific size of the reference nucleic acid. Particularly, a simple analysis of the competition titration experiments is described in which the fluorescent, short fragment of nucleic acid, spanning the exact site-size of the protein-nucleic acid complex, and binding with only a 1:1 stoichiometry to the protein, is used as a reference macromolecule. Although the MCT method is predominantly discussed as applied to studying protein-nucleic acid interactions, it can generally be applied to any ligand-macromolecule system by monitoring the association reaction using the spectroscopic signal originating from the reference macromolecule in the presence of the competing macromolecule, whose interaction parameters with the ligand are to be determined. Copyright © 2011 Elsevier Inc. All rights reserved.

  2. A statistical model of macromolecules dynamics for Fluorescence Correlation Spectroscopy data analysis

    Directory of Open Access Journals (Sweden)

    Dmitri Koroliouk

    2016-08-01

    Full Text Available In this paper, we propose a new mathematical model to describe the mechanisms of biological macromolecules interactions. Our model consists of a discrete stationary random sequence given by a solution of difference stochastic equation, characterized by a drift predictive component and by a diffusion term. The relative statistical estimations are very simple and effective, promising to be a good tool for the mathematical description of collective biological reactions. This paper presents the mathematical model and its verification on a simulated data set, obtained on the basis of the well-known Stokes-Einsteinmodel. In particular, we considered several mix of particles of different diffusion coefficient, respectively: D1=10 mm2/sec and D2=100 mm2/sec. The parameters evaluated by this new mathematical model on simulated data show good estimation accuracy, in comparison with the prior parameters used in the simulations. Furthermore, when analyzing the data for the mix of particles with different diffusion coefficient, the proposed model parameters  (regression and  (square variance of the stochastic component have a good discriminative ability for the molar fraction determination.  In this paper, we propose a new mathematical model to describe the mechanisms of biological macromolecules interactions. Our model consists of a discrete stationary random sequence given by a solution of difference stochastic equation, characterized by a drift predictive component and by a diffusion term. The relative statistical estimations are very simple and effective, promising to be a good tool for mathematical description of collective biological reactions. This paper presents the mathematical model and its verification on simulated data set, obtained on the basis of the well-known Stokes-Einsteinmodel. In particular we considered several mix of particles of different diffusion coefficient, respectively: D1=10 mm2/sec and D2=100 mm2/sec. The parameters

  3. Equilibrium Kinetics Studies and Crystallization Aboard the International Space Station (ISS) Using the Protein Crystallization Apparatus for Microgravity (PCAM)

    Science.gov (United States)

    Achari, Aniruddha; Roeber, Dana F.; Barnes, Cindy L.; Kundrot, Craig E.; Stinson, Thomas N. (Technical Monitor)

    2002-01-01

    Protein Crystallization Apparatus in Microgravity (PCAM) trays have been used in Shuttle missions to crystallize proteins in a microgravity environment. The crystallization experiments are 'sitting drops' similar to that in Cryschem trays, but the reservoir solution is soaked in a wick. From early 2001, crystallization experiments are conducted on the International Space Station using mission durations of months rather than two weeks on previous shuttle missions. Experiments were set up in April 2001 on Flight 6A to characterize the time crystallization experiments will take to reach equilibrium in a microgravity environment using salts, polyethylene glycols and an organic solvent as precipitants. The experiments were set up to gather data for a series of days of activation with different droplet volumes and precipitants. The experimental set up on ISS and results of this study will be presented. These results will help future users of PCAM to choose precipitants to optimize crystallization conditions for their target macromolecules for a particular mission with known mission duration. Changes in crystal morphology and size between the ground and space grown crystals of a protein and a protein -DNA complex flown on the same mission will also be presented.

  4. Last crystals for the CMS chandelier

    CERN Multimedia

    2008-01-01

    In March, the last crystals for CMS’s electromagnetic calorimeter arrived from Russia and China. Like dedicated jewellers crafting an immense chandelier, the CMS ECAL collaborators are working extremely hard to install all the crystals before the start-up of the LHC. One of the last CMS end-cap crystals, complete with identification bar code. Lead tungstate crystals mounted onto one section of the CMS ECAL end caps. Nearly 10 years after the first production crystal arrived at CERN in September 1998, the very last shipment has arrived. These final crystals will be used to complete the end-caps of the electromagnetic calorimeter (ECAL) at CMS. All in all, there are more than 75,000 crystals in the ECAL. The huge quantity of CMS lead tungstate crystals used in the ECAL corresponds to the highest volume ever produced for a single experiment. The excellent quality of the crystals, both in ter...

  5. Is the macromolecule signal tissue-specific in healthy human brain? A (1)H MRS study at 7 Tesla in the occipital lobe.

    Science.gov (United States)

    Schaller, Benoît; Xin, Lijing; Gruetter, Rolf

    2014-10-01

    The macromolecule signal plays a key role in the precision and the accuracy of the metabolite quantification in short-TE (1) H MR spectroscopy. Macromolecules have been reported at 1.5 Tesla (T) to depend on the cerebral studied region and to be age specific. As metabolite concentrations vary locally, information about the profile of the macromolecule signal in different tissues may be of crucial importance. The aim of this study was to investigate, at 7T for healthy subjects, the neurochemical profile differences provided by macromolecule signal measured in two different tissues in the occipital lobe, predominantly composed of white matter tissue or of grey matter tissue. White matter-rich macromolecule signal was relatively lower than the gray matter-rich macromolecule signal from 1.5 to 1.8 ppm and from 2.3 to 2.5 ppm with mean difference over these regions of 7% and 12% (relative to the reference peak at 0.9 ppm), respectively. The neurochemical profiles, when using either of the two macromolecule signals, were similar for 11 reliably quantified metabolites (CRLB occipital lobe at 7T in healthy human brain. Copyright © 2013 Wiley Periodicals, Inc.

  6. Extracting trends from two decades of microgravity macromolecular crystallization history.

    Science.gov (United States)

    Judge, Russell A; Snell, Edward H; van der Woerd, Mark J

    2005-06-01

    Since the 1980s hundreds of macromolecular crystal growth experiments have been performed in the reduced acceleration environment of an orbiting spacecraft. Significant enhancements in structural knowledge have resulted from X-ray diffraction of the crystals grown. Similarly, many samples have shown no improvement or degradation in comparison to those grown on the ground. A complex series of interrelated factors affect these experiments and by building a comprehensive archive of the results it was aimed to identify factors that result in success and those that result in failure. Specifically, it was found that dedicated microgravity missions increase the chance of success when compared with those where crystallization took place as a parasitic aspect of the mission. It was also found that the chance of success could not be predicted based on any discernible property of the macromolecule available to us.

  7. Electrospun ECM macromolecules as biomimetic scaffold for regenerative medicine: challenges for preserving conformation and bioactivity

    Directory of Open Access Journals (Sweden)

    Chiara Emma Campiglio

    2017-05-01

    Full Text Available The extracellular matrix (ECM, the physiological scaffold for cells in vivo, provides structural support to cells and guaranties tissue integrity. At the same time, however, it represents an extremely complex and finely tuned signaling environment that contributes in regulating tissue homeostasis and repair. ECM can bind, release and activate signaling molecules and also modulate cell reaction to soluble factors. Cell-ECM interactions, as a result, are recognized to be critical for physiological wound healing, and consequently in guiding regeneration. Due to its complexity, mimicking ECM chemistry and architecture appears a straightforward strategy to exploit the benefits of a biologically recognizable and cell-instructive environment. As ECM consists primarily of sub-micrometric fibers, electrospinning, a simple and versatile technique, has attracted the majority efforts aimed at reprocessing of biologically occurring molecules. However, the ability to trigger specific cellular behavior is likely to depend on both the chemical and conformational properties of biological molecules. As a consequence, when ECM macromolecules are electrospun, investigating the effect of processing on their structure, and the extent to which their potential in directing cellular behavior is preserved, appears crucial. In this perspective, this review explores the electrospinning of ECM molecules specifically focusing on the effect of processing on polymer structure and on in vitro or in vivo experiments designed to confirm the maintenance of their instructive role.

  8. Needle-free delivery of macromolecules through the skin using controllable jet injectors.

    Science.gov (United States)

    Hogan, Nora C; Taberner, Andrew J; Jones, Lynette A; Hunter, Ian W

    2015-01-01

    Transdermal delivery of drugs has a number of advantages in comparison to other routes of administration. The mechanical properties of skin, however, impose a barrier to administration and so most compounds are administered using hypodermic needles and syringes. In order to overcome some of the issues associated with the use of needles, a variety of non-needle devices based on jet injection technology has been developed. Jet injection has been used primarily for vaccine administration but has also been used to deliver macromolecules such as hormones, monoclonal antibodies and nucleic acids. A critical component in the more recent success of jet injection technology has been the active control of pressure applied to the drug during the time course of injection. Jet injection systems that are electronically controllable and reversible offer significant advantages over conventional injection systems. These devices can consistently create the high pressures and jet speeds necessary to penetrate tissue and then transition smoothly to a lower jet speed for delivery of the remainder of the desired dose. It seems likely that in the future this work will result in smart drug delivery systems incorporated into personal medical devices and medical robots for in-home disease management and healthcare.

  9. Development of a Prototype System for Archiving Integrative/Hybrid Structure Models of Biological Macromolecules.

    Science.gov (United States)

    Vallat, Brinda; Webb, Benjamin; Westbrook, John D; Sali, Andrej; Berman, Helen M

    2018-04-09

    Essential processes in biology are carried out by large macromolecular assemblies, whose structures are often difficult to determine by traditional methods. Increasingly, researchers combine measured data and computed information from several complementary methods to obtain "hybrid" or "integrative" structural models of macromolecules and their assemblies. These integrative/hybrid (I/H) models are not archived in the PDB because of the absence of standard data representations and processing mechanisms. Here we present the development of data standards and a prototype system for archiving I/H models. The data standards provide the definitions required for representing I/H models that span multiple spatiotemporal scales and conformational states, as well as spatial restraints derived from different experimental techniques. Based on these data definitions, we have built a prototype system called PDB-Dev, which provides the infrastructure necessary to archive I/H structural models. PDB-Dev is now accepting structures and is open to the community for new submissions. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Perspective: On the importance of hydrodynamic interactions in the subcellular dynamics of macromolecules

    Science.gov (United States)

    Skolnick, Jeffrey

    2016-09-01

    An outstanding challenge in computational biophysics is the simulation of a living cell at molecular detail. Over the past several years, using Stokesian dynamics, progress has been made in simulating coarse grained molecular models of the cytoplasm. Since macromolecules comprise 20%-40% of the volume of a cell, one would expect that steric interactions dominate macromolecular diffusion. However, the reduction in cellular diffusion rates relative to infinite dilution is due, roughly equally, to steric and hydrodynamic interactions, HI, with nonspecific attractive interactions likely playing rather a minor role. HI not only serve to slow down long time diffusion rates but also cause a considerable reduction in the magnitude of the short time diffusion coefficient relative to that at infinite dilution. More importantly, the long range contribution of the Rotne-Prager-Yamakawa diffusion tensor results in temporal and spatial correlations that persist up to microseconds and for intermolecular distances on the order of protein radii. While HI slow down the bimolecular association rate in the early stages of lipid bilayer formation, they accelerate the rate of large scale assembly of lipid aggregates. This is suggestive of an important role for HI in the self-assembly kinetics of large macromolecular complexes such as tubulin. Since HI are important, questions as to whether continuum models of HI are adequate as well as improved simulation methodologies that will make simulations of more complex cellular processes practical need to be addressed. Nevertheless, the stage is set for the molecular simulations of ever more complex subcellular processes.

  11. Insights into the key roles of epigenetics in matrix macromolecules-associated wound healing.

    Science.gov (United States)

    Piperigkou, Zoi; Götte, Martin; Theocharis, Achilleas D; Karamanos, Nikos K

    2017-10-24

    Extracellular matrix (ECM) is a dynamic network of macromolecules, playing a regulatory role in cell functions, tissue regeneration and remodeling. Wound healing is a tissue repair process necessary for the maintenance of the functionality of tissues and organs. This highly orchestrated process is divided into four temporally overlapping phases, including hemostasis, inflammation, proliferation and tissue remodeling. The dynamic interplay between ECM and resident cells exerts its critical role in many aspects of wound healing, including cell proliferation, migration, differentiation, survival, matrix degradation and biosynthesis. Several epigenetic regulatory factors, such as the endogenous non-coding microRNAs (miRNAs), are the drivers of the wound healing response. microRNAs have pivotal roles in regulating ECM composition during wound healing and dermal regeneration. Their expression is associated with the distinct phases of wound healing and they serve as target biomarkers and targets for systematic regulation of wound repair. In this article we critically present the importance of epigenetics with particular emphasis on miRNAs regulating ECM components (i.e. glycoproteins, proteoglycans and matrix proteases) that are key players in wound healing. The clinical relevance of miRNA targeting as well as the delivery strategies designed for clinical applications are also presented and discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Electric double layer and electrokinetic potential of pectic macromolecules in sugar beet

    Directory of Open Access Journals (Sweden)

    Kuljanin Tatjana A.

    2008-01-01

    Full Text Available Electrokinetic potential is an important property of colloidal particles and, regarding the fact that it is a well defined and easily measurable property, it is considered to be a permanent characteristic of a particular colloidal system. In fact, it is a measure of electrokinetic charge that surrounds the colloidal particle in a solution and is in direct proportion with the mobility of particles in an electric field. Gouy-Chapman-Stern-Graham's model of electric double layer was adopted and it was proven experimentally that the addition of Cu++ ions to sugar beet pectin caused a reduction in the negative electrokinetic potential proportional to the increase of Cu++ concentration. Higher Cu++ concentrations increased the proportion of cation specific adsorption (Cu++ and H+ with regard to electrostatic Coulombic forces. Consequently, there is a shift in the shear plane between the fixed and diffuse layers directed towards the diffuse layer, i.e. towards its compression and decrease in the electrokinetic potential or even charge inversion of pectin macromolecules.

  13. Synthesis of naturally-derived macromolecules through simplified electrochemically mediated ATRP

    Directory of Open Access Journals (Sweden)

    Paweł Chmielarz

    2017-11-01

    Full Text Available The flavonoid-based macroinitiator was received for the first time by the transesterification reaction of quercetin with 2-bromoisobutyryl bromide. In accordance with the “grafting from” strategy, a naturally-occurring star-like polymer with a polar 3,3',4',5,6-pentahydroxyflavone core and hydrophobic poly(tert-butyl acrylate (PtBA side arms was synthesized via a simplified electrochemically mediated ATRP (seATRP, utilizing only 78 ppm by weight (wt of a catalytic CuII complex. To demonstrate the possibility of temporal control, seATRP was carried out utilizing a multiple-step potential electrolysis. The rate of the polymerizations was well-controlled by applying optimal potential values during preparative electrolysis to prevent the possibility of intermolecular coupling of the growing polymer arms. This appears to be the first report using on-demand seATRP for the synthesis of QC-(PtBA-Br5 pseudo-star polymers. The naturally-derived macromolecules showed narrow MWDs (Đ = 1.08–1.11. 1H NMR spectral results confirm the formation of quercetin-based polymers. These new flavonoid-based polymer materials may find applications as antifouling coatings and drug delivery systems.

  14. Electronic method for autofluorography of macromolecules on two-d matrices

    International Nuclear Information System (INIS)

    Case, A.L.; Davidson, J.B.

    1983-01-01

    A method for detecting, localizing, and quantifying macromolecules contained in a two-dimensional matrix is provided which employs a television-based position sensitive detection system. A molecule-containing matrix may be produced by conventional means to produce spots of light at the molecule locations which are detected by the television system. The matrix , such as a gel matrix, is exposed to an electronic camera system including an image-intensifier and secondary electron conduction camera capable of light integrating times of many minutes. A light image stored in the form of a charge image on the camera tube target is scanned by conventional television techniques, digitized, and stored in a digital memory. Intensity of any point on the image may be determined from the number at the memory address of the point. The entire image may be displayed on a television monitor for inspection and photographing or individual spots may be analyzed through selected readout of the memory locations. Compared to conventional film exposure methods, the exposure time may be reduced 100-1000 times

  15. Identification of Characteristic Macromolecules of Escherichia coli Genotypes by Atomic Force Microscope Nanoscale Mechanical Mapping

    Science.gov (United States)

    Chang, Alice Chinghsuan; Liu, Bernard Haochih

    2018-02-01

    The categorization of microbial strains is conventionally based on the molecular method, and seldom are the morphological characteristics in the bacterial strains studied. In this research, we revealed the macromolecular structures of the bacterial surface via AFM mechanical mapping, whose resolution was not only determined by the nanoscale tip size but also the mechanical properties of the specimen. This technique enabled the nanoscale study of membranous structures of microbial strains with simple specimen preparation and flexible working environments, which overcame the multiple restrictions in electron microscopy and label-enable biochemical analytical methods. The characteristic macromolecules located among cellular surface were considered as surface layer proteins and were found to be specific to the Escherichia coli genotypes, from which the averaged molecular sizes were characterized with diameters ranging from 38 to 66 nm, and the molecular shapes were kidney-like or round. In conclusion, the surface macromolecular structures have unique characteristics that link to the E. coli genotype, which suggests that the genomic effects on cellular morphologies can be rapidly identified using AFM mechanical mapping. [Figure not available: see fulltext.

  16. New beamline dedicated to solution scattering from biological macromolecules at the ESRF

    International Nuclear Information System (INIS)

    Pernot, P; Theveneau, P; Giraud, T; Fernandes, R Nogueira; Nurizzo, D; Spruce, D; Surr, J; McSweeney, S; Round, A; Felisaz, F; Foedinger, L; Gobbo, A; Huet, J; Villard, C; Cipriani, F

    2010-01-01

    The new bio-SAXS beamline (ID14-3 at the ESRF, Grenoble, France) is dedicated exclusively to small-angle scattering experiments of biological macromolecules in solution and has been in user operation since November 2008. Originally a protein crystallography beamline, ID14-3 was refurbished, still as a part of the ESRF Structural Biology group, with the main aim to provide a facility with 'quick and easy' access to satisfy rapidly growing demands from crystallographers, biochemists and structural biologists. The beamline allows manual and automatic sample loading/unloading, data collection, processing (conversion of a 2D image to a normalized 1D X-ray scattering profile) and analysis. The users obtain on-line standard data concerning the size (radius of gyration, maximum dimension and volume) and molecular weight of samples which allow on-the fly ab-inito shape reconstruction in order to provide feedback enabling the data collection strategies to be optimized. Automation of sample loading is incorporated on the beamline using a device constructed in collaboration between the EMBL (Grenoble and Hamburg outstations) and the ESRF. Semi/automated data analysis is implemented following the model of the SAXS facility at X33, EMBL Hamburg. This paper describes the bio-SAXS beamline and set-up characteristics together with the examples of user data obtained.

  17. Antioxidant, antimicrobial, cell viability and enzymatic inhibitory of antioxidant polymers as biological macromolecules.

    Science.gov (United States)

    Hashemi Gahruie, Hadi; Niakousari, Mehrdad

    2017-11-01

    Polymeric antioxidants such as Catechinaldehyde Polycondensates, Catechin-acelaldehydepolycondensates, Flavonoid-grafted chitosan fibers, Ferulate hydrogel, Dextran ferulate hydrogel, Starch-quercetin conjugate, Gallic acid- and Caffeic acid-functionalized chitosan, Gallic acid - chitosan conjugate, Poly(rutin), Gallic acid grafted chitosan, Dextran-Catechin Conjugate belong to biological macromolecules. These kinds of compounds have stronger antioxidant potential and pharmacokinetic activities, as compared to similar low molecular weight preservatives. Most of these compounds sources are either antioxidants with low molecules polymerization, or polymers conjugation such as synthetic or natural preservatives. Additives are well known as being an important ingredient of food products due to their strong preservative potential. Many researchers and industries attempt to find synthesize materials with the same antioxidant potential and higher stability than the similar compounds with low molecular weight. Recently, macromolecular antioxidants have received wide attention as food additives and dietary supplements in functional foods. It seems that the main usage of these compounds is in the food packaging industry. Most of these compounds have strong antioxidant, antimicrobial, cell viability and enzymatic inhibitory properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Film Self-Assembly of Oppositely Charged Macromolecules Triggered by Electrochemistry through a Morphogenic Approach.

    Science.gov (United States)

    Dochter, Alexandre; Garnier, Tony; Pardieu, Elodie; Chau, Nguyet Trang Thanh; Maerten, Clément; Senger, Bernard; Schaaf, Pierre; Jierry, Loïc; Boulmedais, Fouzia

    2015-09-22

    The development of new surface functionalization methods that are easy to use, versatile, and allow local deposition represents a real scientific challenge. Overcoming this challenge, we present here a one-pot process that consists in self-assembling, by electrochemistry on an electrode, films made of oppositely charged macromolecules. This method relies on a charge-shifting polyanion, dimethylmaleic-modified poly(allylamine) (PAHd), that undergoes hydrolysis at acidic pH, leading to an overall switching of its charge. When a mixture of the two polyanions, PAHd and poly(styrenesulfonate) (PSS), is placed in contact with an electrode, where the pH is decreased locally by electrochemistry, the transformation of PAHd into a polycation (PAH) leads to the continuous self-assembly of a nanometric PAH/PSS film by electrostatic interactions. The pH decrease is obtained by the electrochemical oxidation of hydroquinone, which produces protons locally over nanometric distances. Using a negatively charged enzyme, alkaline phosphatase (AP), instead of PSS, this one-pot process allows the creation of enzymatically active films. Under mild conditions, self-assembled PAH/AP films have an enzymatic activity which is adjustable simply by controlling the self-assembly time. The selective functionalization of microelectrode arrays by PAH/AP was achieved, opening the route toward miniaturized biosensors.

  19. Measurements of Protein Crystal Face Growth Rates

    Science.gov (United States)

    Gorti, S.

    2014-01-01

    Protein crystal growth rates will be determined for several hyperthermophile proteins.; The growth rates will be assessed using available theoretical models, including kinetic roughening.; If/when kinetic roughening supersaturations are established, determinations of protein crystal quality over a range of supersaturations will also be assessed.; The results of our ground based effort may well address the existence of a correlation between fundamental growth mechanisms and protein crystal quality.

  20. Applications of the quasi-elastic light scattering to the study of dynamic properties of charged macro-molecules

    International Nuclear Information System (INIS)

    Gouesin-Menez, Renee

    1979-01-01

    The object of this research thesis is to study the modifications of dynamic properties of a macromolecule under the influence of variations of its medium, by using a frequency analysis of the spectrum of light scattered by a solution of particles. Thus, an important part of this thesis addresses the study and development of the scattering method and of its analysis by 'photon pulses', and the development and adjustment of an electrophoretic device to study light scattering by molecules submitted to an electric field. Then, hydrodynamic characteristics of some macromolecules have been measured with or without electric field. The studied molecular systems have been: calibrated spheres of latex polystyrene, a globular protein (bovine serum albumin), a polysaccharide (under the form of a rigid short stick), a flexible linear polyelectrolyte (polymethacrylate), and two DNA samples

  1. Steady-State Linear and Non-linear Optical Spectroscopy of Organic Chromophores and Bio-macromolecules.

    Science.gov (United States)

    Marazzi, Marco; Gattuso, Hugo; Monari, Antonio; Assfeld, Xavier

    2018-01-01

    Bio-macromolecules as DNA, lipid membranes and (poly)peptides are essential compounds at the core of biological systems. The development of techniques and methodologies for their characterization is therefore necessary and of utmost interest, even though difficulties can be experienced due to their intrinsic complex nature. Among these methods, spectroscopies, relying on optical properties are especially important to determine their macromolecular structures and behaviors, as well as the possible interactions and reactivity with external dyes-often drugs or pollutants-that can (photo)sensitize the bio-macromolecule leading to eventual chemical modifications, thus damages. In this review, we will focus on the theoretical simulation of electronic spectroscopies of bio-macromolecules, considering their secondary structure and including their interaction with different kind of (photo)sensitizers. Namely, absorption, emission and electronic circular dichroism (CD) spectra are calculated and compared with the available experimental data. Non-linear properties will be also taken into account by two-photon absorption, a highly promising technique (i) to enhance absorption in the red and infra-red windows and (ii) to enhance spatial resolution. Methodologically, the implications of using implicit and explicit solvent, coupled to quantum and thermal samplings of the phase space, will be addressed. Especially, hybrid quantum mechanics/molecular mechanics (QM/MM) methods are explored for a comparison with solely QM methods, in order to address the necessity to consider an accurate description of environmental effects on spectroscopic properties of biological systems.

  2. Rotational Diffusion of Macromolecules and Nanoparticles Modeled as Non-Overlapping Bead Arrays in an Effective Medium

    Directory of Open Access Journals (Sweden)

    Umar Twahir

    2011-05-01

    Full Text Available In this work, the retarding influence of a gel on the rotational motion of a macromolecule is investigated within the framework of the Effective Medium (EM model. This is an extension of an earlier study that considered the effect of a gel on the translational motion of a macromolecule [Allison, S. et al. J. Phys. Chem. B 2008, 112, 5858-5866]. The macromolecule is modeled as an array of non-overlapping spherical beads with no restriction placed on their size or configuration. Specific applications include the rotational motion of right circular cylinders and wormlike chains modeled as strings of identical touching beads. The procedure is then used to examine the electric birefringence decay of a 622 base pair DNA fragment in an agarose gel. At low gel concentration (M £ 0.010 gm/mL, good agreement between theory and experiment is achieved if the persistence length of DNA is taken to be 65 nm and the gel fiber radius of agarose is taken to be 2.5 nm. At higher gel concentrations, the EM model substantially underestimates the rotational relaxation time of DNA and this can be attributed to the onset of direct interactions that become significant when the effective particle size becomes comparable to the mean gel fiber spacing.

  3. Supramolecular Assembly of Comb-like Macromolecules Induced by Chemical Reactions that Modulate the Macromolecular Interactions In Situ.

    Science.gov (United States)

    Xia, Hongwei; Fu, Hailin; Zhang, Yanfeng; Shih, Kuo-Chih; Ren, Yuan; Anuganti, Murali; Nieh, Mu-Ping; Cheng, Jianjun; Lin, Yao

    2017-08-16

    Supramolecular polymerization or assembly of proteins or large macromolecular units by a homogeneous nucleation mechanism can be quite slow and require specific solution conditions. In nature, protein assembly is often regulated by molecules that modulate the electrostatic interactions of the protein subunits for various association strengths. The key to this regulation is the coupling of the assembly process with a reversible or irreversible chemical reaction that occurs within the constituent subunits. However, realizing this complex process by the rational design of synthetic molecules or macromolecules remains a challenge. Herein, we use a synthetic polypeptide-grafted comb macromolecule to demonstrate how the in situ modulation of interactions between the charged macromolecules affects their resulting supramolecular structures. The kinetics of structural formation was studied and can be described by a generalized model of nucleated polymerization containing secondary pathways. Basic thermodynamic analysis indicated the delicate role of the electrostatic interactions between the charged subunits in the reaction-induced assembly process. This approach may be applicable for assembling a variety of ionic soft matters that are amenable to chemical reactions in situ.

  4. Steady-State Linear and Non-linear Optical Spectroscopy of Organic Chromophores and Bio-macromolecules

    Directory of Open Access Journals (Sweden)

    Marco Marazzi

    2018-04-01

    Full Text Available Bio-macromolecules as DNA, lipid membranes and (polypeptides are essential compounds at the core of biological systems. The development of techniques and methodologies for their characterization is therefore necessary and of utmost interest, even though difficulties can be experienced due to their intrinsic complex nature. Among these methods, spectroscopies, relying on optical properties are especially important to determine their macromolecular structures and behaviors, as well as the possible interactions and reactivity with external dyes—often drugs or pollutants—that can (photosensitize the bio-macromolecule leading to eventual chemical modifications, thus damages. In this review, we will focus on the theoretical simulation of electronic spectroscopies of bio-macromolecules, considering their secondary structure and including their interaction with different kind of (photosensitizers. Namely, absorption, emission and electronic circular dichroism (CD spectra are calculated and compared with the available experimental data. Non-linear properties will be also taken into account by two-photon absorption, a highly promising technique (i to enhance absorption in the red and infra-red windows and (ii to enhance spatial resolution. Methodologically, the implications of using implicit and explicit solvent, coupled to quantum and thermal samplings of the phase space, will be addressed. Especially, hybrid quantum mechanics/molecular mechanics (QM/MM methods are explored for a comparison with solely QM methods, in order to address the necessity to consider an accurate description of environmental effects on spectroscopic properties of biological systems.

  5. Steady-State Linear and Non-linear Optical Spectroscopy of Organic Chromophores and Bio-macromolecules

    Science.gov (United States)

    Marazzi, Marco; Gattuso, Hugo; Monari, Antonio; Assfeld, Xavier

    2018-04-01

    Bio-macromolecules as DNA, lipid membranes and (poly)peptides are essential compounds at the core of biological systems. The development of techniques and methodologies for their characterization is therefore necessary and of utmost interest, even though difficulties can be experienced due to their intrinsic complex nature. Among these methods, spectroscopies, relying on optical properties are especially important to determine their macromolecular structures and behaviors, as well as the possible interactions and reactivity with external dyes – often drugs or pollutants – that can (photo)sensitize the bio-macromolecule leading to eventual chemical modifications, thus damages. In this review, we will focus on the theoretical simulation of electronic spectroscopies of bio-macromolecules, considering their secondary structure and including their interaction with different kind of (photo)sensitizers. Namely, absorption, emission and electronic circular dichroism (CD) spectra are calculated and compared with the available experimental data. Non-linear properties will be also taken into account by two-photon absorption, a highly promising technique (i) to enhance absorption in the red and infra-red windows and (ii) to enhance spatial resolution. Methodologically, the implications of using implicit and explicit solvent, coupled to quantum and thermal samplings of the phase space, will be addressed. Especially, hybrid quantum mechanics/ molecular mechanics (QM/MM) methods are explored for a comparison with solely QM methods, in order to address the necessity to consider an accurate description of environmental effects on spectroscopic properties of biological systems.

  6. A thermally tunable inverse opal photonic crystal for monitoring glass transition.

    Science.gov (United States)

    Sun, Liguo; Xie, Zhuoying; Xu, Hua; Xu, Ming; Han, Guozhi; Wang, Cheng; Bai, Xuduo; Gu, ZhongZe

    2012-03-01

    An optical method was developed to monitor the glass transition of the polymer by taking advantage of reflection spectrum change of the thermally tunable inverse opal photonic crystal. The thermally tunable photonic bands of the polymer inverse opal photonic crystal were traceable to the segmental motion of macromolecules, and the segmental motion was temperature dependent. By observing the reflection spectrum change of the polystyrene inverse opal photonic crystal during thermal treatment, the glass transition temperature of polystyrene was gotten. Both changes of the position and intensity of the reflection peak were observed during the glass transition process of the polystyrene inverse opal photonic crystal. The optical change of inverse opal photonic crystal was so large that the glass transition temperature could even be estimated by naked eyes. The glass transition temperature derived from this method was consistent with the values measured by differential scanning calorimeter.

  7. Systematic Procedure for Generating Operational Policies to Achieve Target Crystal Size Distribution (CSD) in Batch Cooling Crystallization

    DEFF Research Database (Denmark)

    Abdul Samad, Noor Asma Fazli; Singh, Ravendra; Sin, Gürkan

    2011-01-01

    Batch cooling crystallization is one of the important unit operations involving separation of solid-liquid phases. Usually the most common crystal product qualities are directly related to the crystal size distribution (CSD). However the main difficulty in batch crystallization is to obtain a uni...

  8. The interstitial distribution of macromolecules in rat tumours is influenced by the negatively charged matrix components.

    Science.gov (United States)

    Wiig, Helge; Gyenge, Christina C; Tenstad, Olav

    2005-09-01

    Knowledge of macromolecular distribution volumes is essential in understanding fluid transport within normal and pathological tissues. In this study in vivo we determined the distribution volumes of several macromolecules, including one monoclonal antibody, in tumours and tested whether charges associated with the tumour extracellular matrix influence their available volumes. Steady state levels of the monoclonal antibody trastuzumab (Herceptin) (pI = 9.2), IgG (pI = 7.6) as well as native (pI = 5.0) and cationized albumin (pI = 7.6) were established in rats bearing dimethylbenzanthracene (DMBA)-induced mammary tumours by continuous infusion using osmotic minipumps. After a 5-7 day infusion period, the rats were nephrectomized and the extracellular volume was determined with 51Cr-labelled EDTA. Plasma volumes were measured with 125I-labelled human serum albumin or rat IgM in a separate series. Steady state concentrations of probes were determined in the interstitial fluid that was isolated by centrifugation from tumours or by post mortem wick implantation in the back skin. Calculations were made for interstitial fluid volume (Vi), along with the available (Va/Vi) and excluded (Ve/Vi) relative interstitial volume fractions. The Ve/Vi for the positively charged trastuzumab in tumours averaged 0.29 +/- 0.03 (n = 16), a value which was significantly lower than the corresponding one for IgG of 0.36 +/- 0.02 (n = 16). Native albumin was excluded from 38% of the tumour interstitial fluid, whereas cationization of albumin reduced the excluded volume by approximately 50%. Our experiments suggest that the tumour interstitium acts as a negatively charged matrix and is an important factor in determining the macromolecular distribution volume.

  9. Permeation of macromolecules into the renal glomerular basement membrane and capture by the tubules

    Science.gov (United States)

    Lawrence, Marlon G.; Altenburg, Michael K.; Sanford, Ryan; Willett, Julian D.; Bleasdale, Benjamin; Ballou, Byron; Wilder, Jennifer; Li, Feng; Miner, Jeffrey H.; Berg, Ulla B.; Smithies, Oliver

    2017-01-01

    How the kidney prevents urinary excretion of plasma proteins continues to be debated. Here, using unfixed whole-mount mouse kidneys, we show that fluorescent-tagged proteins and neutral dextrans permeate into the glomerular basement membrane (GBM), in general agreement with Ogston's 1958 equation describing how permeation into gels is related to molecular size. Electron-microscopic analyses of kidneys fixed seconds to hours after injecting gold-tagged albumin, negatively charged gold nanoparticles, and stable oligoclusters of gold nanoparticles show that permeation into the lamina densa of the GBM is size-sensitive. Nanoparticles comparable in size with IgG dimers do not permeate into it. IgG monomer-sized particles permeate to some extent. Albumin-sized particles permeate extensively into the lamina densa. Particles traversing the lamina densa tend to accumulate upstream of the podocyte glycocalyx that spans the slit, but none are observed upstream of the slit diaphragm. At low concentrations, ovalbumin-sized nanoparticles reach the primary filtrate, are captured by proximal tubule cells, and are endocytosed. At higher concentrations, tubular capture is saturated, and they reach the urine. In mouse models of Pierson’s or Alport’s proteinuric syndromes resulting from defects in GBM structural proteins (laminin β2 or collagen α3 IV), the GBM is irregularly swollen, the lamina densa is absent, and permeation is increased. Our observations indicate that size-dependent permeation into the lamina densa of the GBM and the podocyte glycocalyx, together with saturable tubular capture, determines which macromolecules reach the urine without the need to invoke direct size selection by the slit diaphragm. PMID:28246329

  10. Conformation-independent structural comparison of macromolecules with ProSMART

    International Nuclear Information System (INIS)

    Nicholls, Robert A.; Fischer, Marcus; McNicholas, Stuart; Murshudov, Garib N.

    2014-01-01

    The Procrustes Structural Matching Alignment and Restraints Tool (ProSMART) has been developed to allow local comparative structural analyses independent of the global conformations and sequence homology of the compared macromolecules. This allows quick and intuitive visualization of the conservation of backbone and side-chain conformations, providing complementary information to existing methods. The identification and exploration of (dis)similarities between macromolecular structures can help to gain biological insight, for instance when visualizing or quantifying the response of a protein to ligand binding. Obtaining a residue alignment between compared structures is often a prerequisite for such comparative analysis. If the conformational change of the protein is dramatic, conventional alignment methods may struggle to provide an intuitive solution for straightforward analysis. To make such analyses more accessible, the Procrustes Structural Matching Alignment and Restraints Tool (ProSMART) has been developed, which achieves a conformation-independent structural alignment, as well as providing such additional functionalities as the generation of restraints for use in the refinement of macromolecular models. Sensible comparison of protein (or DNA/RNA) structures in the presence of conformational changes is achieved by enforcing neither chain nor domain rigidity. The visualization of results is facilitated by popular molecular-graphics software such as CCP4mg and PyMOL, providing intuitive feedback regarding structural conservation and subtle dissimilarities between close homologues that can otherwise be hard to identify. Automatically generated colour schemes corresponding to various residue-based scores are provided, which allow the assessment of the conservation of backbone and side-chain conformations relative to the local coordinate frame. Structural comparison tools such as ProSMART can help to break the complexity that accompanies the constantly growing

  11. Transport of macromolecules and particles at target sites for deposition of air pollutants

    International Nuclear Information System (INIS)

    Crocker, T.T.; Bhalla, D.K.

    1986-01-01

    This study analyzed rats' nasal, tracheal and bronchoalveolar epithelial permeability to macromolecules after they were exposed, in 2- or 4-hour periods of rest or exercise, to ozone (O3) (0.6, 0.8 or 2 ppm), nitrogen dioxide (NO2) (2.5, 6 or 12 ppm) or formaldehyde (10 ppm). Exercise was performed on a treadmill operated at a speed that led to a 2-fold increase in oxygen consumption. Histopathologic and electron microscopic cytochemical and autoradiographic studies were performed to identify the structural aspects of mucosal response. In rats not exposed to pollutants, the quantity of macromolecular tracers (99mTc-DTPA, 125I-BSA) in blood sampled 6, 7, 8, 9 and 10 minutes after a slow 5-minute instillation of comparable quantities of tracer molecules in the lumen of each zone, was lowest in nasal, highest in tracheal, and intermediate in the bronchoalveolar region. Exposure of resting rats to O3 did not affect nasal permeability, but tracheal and bronchoalveolar permeabilities increased by 2-fold 1 hour after the exposure. In rats exposed at rest to O3, tracheal permeability was no longer elevated 24 hours after exposure, but bronchoalveolar permeability remained elevated at 24 hours after exposure and was normal at 48 hours. Exposure during exercise increased the effect of O3 in the trachea and in the bronchoalveolar zone. However, exercise also prolonged the duration of the O3 effect on the tracheal zone from 1 hour to 24 hours and, in the bronchoalveolar zone, from 24 hours to 48 hours. Histologically, focal inflammatory lesions in the alveolar zone were maximal at 48 hours after a 4-hour resting exposure to O3. After exposure during exercise, the area of lung involved by lesions increased 4- to 7-fold above the lesion-bearing area in rats exposed while resting

  12. Conformation-independent structural comparison of macromolecules with ProSMART

    Energy Technology Data Exchange (ETDEWEB)

    Nicholls, Robert A., E-mail: nicholls@mrc-lmb.cam.ac.uk [MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH (United Kingdom); Fischer, Marcus [University of California San Francisco, San Francisco, CA 94158 (United States); McNicholas, Stuart [University of York, Heslington, York YO10 5DD (United Kingdom); Murshudov, Garib N. [MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH (United Kingdom)

    2014-09-01

    The Procrustes Structural Matching Alignment and Restraints Tool (ProSMART) has been developed to allow local comparative structural analyses independent of the global conformations and sequence homology of the compared macromolecules. This allows quick and intuitive visualization of the conservation of backbone and side-chain conformations, providing complementary information to existing methods. The identification and exploration of (dis)similarities between macromolecular structures can help to gain biological insight, for instance when visualizing or quantifying the response of a protein to ligand binding. Obtaining a residue alignment between compared structures is often a prerequisite for such comparative analysis. If the conformational change of the protein is dramatic, conventional alignment methods may struggle to provide an intuitive solution for straightforward analysis. To make such analyses more accessible, the Procrustes Structural Matching Alignment and Restraints Tool (ProSMART) has been developed, which achieves a conformation-independent structural alignment, as well as providing such additional functionalities as the generation of restraints for use in the refinement of macromolecular models. Sensible comparison of protein (or DNA/RNA) structures in the presence of conformational changes is achieved by enforcing neither chain nor domain rigidity. The visualization of results is facilitated by popular molecular-graphics software such as CCP4mg and PyMOL, providing intuitive feedback regarding structural conservation and subtle dissimilarities between close homologues that can otherwise be hard to identify. Automatically generated colour schemes corresponding to various residue-based scores are provided, which allow the assessment of the conservation of backbone and side-chain conformations relative to the local coordinate frame. Structural comparison tools such as ProSMART can help to break the complexity that accompanies the constantly growing

  13. Calculation of X-ray scattering curves and electron distance distribution functions of biological macromolecules in solution using the PROTEIN DATA BANK

    International Nuclear Information System (INIS)

    Mueller, J.J.; Friedrichowicz, E.; Nothnagel, A.; Wunderlich, T.; Ziehlsdorf, E.; Damaschun, G.

    1983-01-01

    The wide angle X-ray scattering curve, the electron distance distribution function and the solvent excluded volume of a macromolecule in solution are calculated from the atomic coordinates contained in the PROTEIN DATA BANK. The structures and the projections of the excluded volumes are depicted using molecule graphic routines. The described computer programs are used to determine the three-dimensional structure of macromolecules in solution from wide angle X-ray scattering data. (author)

  14. Helium crystals

    International Nuclear Information System (INIS)

    Lipson, S.G.

    1987-01-01

    Hexagonal close-packed helium crystals in equilibrium with superfluid have been found to be one of the few systems in which an anisotropic solid comes into true thermodynamic equilibrium with its melt. The discovery of roughening transitions at the liquid-solid interface have shown this system to be ideal for the study of the statistical mechanics of interface structures. We describe the effect of roughening on the shape and growth of macroscopic crystals from both the theoretical and experimental points of view. (author)

  15. High-quality photonic crystals with a nearly complete band gap obtained by direct inversion of woodpile templates with titanium dioxide.

    Science.gov (United States)

    Marichy, Catherine; Muller, Nicolas; Froufe-Pérez, Luis S; Scheffold, Frank

    2016-02-25

    Photonic crystal materials are based on a periodic modulation of the dielectric constant on length scales comparable to the wavelength of light. These materials can exhibit photonic band gaps; frequency regions for which the propagation of electromagnetic radiation is forbidden due to the depletion of the density of states. In order to exhibit a full band gap, 3D PCs must present a threshold refractive index contrast that depends on the crystal structure. In the case of the so-called woodpile photonic crystals this threshold is comparably low, approximately 1.9 for the direct structure. Therefore direct or inverted woodpiles made of high refractive index materials like silicon, germanium or titanium dioxide are sought after. Here we show that, by combining multiphoton lithography and atomic layer deposition, we can achieve a direct inversion of polymer templates into TiO2 based photonic crystals. The obtained structures show remarkable optical properties in the near-infrared region with almost perfect specular reflectance, a transmission dip close to the detection limit and a Bragg length comparable to the lattice constant.

  16. A Test of Macromolecular Crystallization in Microgravity: Large, Well-Ordered Insulin Crystals

    Science.gov (United States)

    Borgstahl, Gloria E. O.; Vahedi-Faridi, Ardeschir; Lovelace, Jeff; Bellamy, Henry D.; Snell, Edward H.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Crystals of insulin grown in microgravity on space shuttle mission STS-95 were extremely well-ordered and unusually large (many > 2 mm). The physical characteristics of six microgravity and six earth-grown crystals were examined by X-ray analysis employing superfine f slicing and unfocused synchrotron radiation. This experimental setup allowed hundreds of reflections to be precisely examined for each crystal in a short period of time. The microgravity crystals were on average 34 times larger, had 7 times lower mosaicity, had 54 times higher reflection peak heights and diffracted to significantly higher resolution than their earth grown counterparts. A single mosaic domain model could account for reflections in microgravity crystals whereas reflections from earth crystals required a model with multiple mosaic domains. This statistically significant and unbiased characterization indicates that the microgravity environment was useful for the improvement of crystal growth and resultant diffraction quality in insulin crystals and may be similarly useful for macromolecular crystals in general.

  17. FUNCTION OF PHLOEM-BORNE INFORMATION MACROMOLECULES IN INTEGRATING PLANT GROWTH & DEVELOPMENT

    Energy Technology Data Exchange (ETDEWEB)

    William J. Lucas

    2012-11-12

    Studies on higher plants have revealed the operation of cell-to-cell and long-distance communication networks that mediate the transport of information macromolecules, such as proteins and RNA. Based on the findings from this DOE-funded project and results from other groups, it is now well established that the enucleate sieve tube system of the angiosperms contains a complex set of proteins including RNA binding proteins as well as a unique population of RNA molecules, comprised of both mRNA and small RNA species. Hetero-grafting experiments demonstrated that delivery of such RNA molecules, into the scion, is highly correlated with changes in developmental phenotypes. Furthermore, over the course of this project, our studies showed that plasmodesmata and the phloem are intimately involved in the local and systemic spread of sequence-specific signals that underlie gene silencing in plants. Major advances were also made in elucidating the underlying mechanisms that operate to mediate the selective entry and exit of proteins and RNA into and out of the phloem translocation stream. Our pioneering studies identified the first plant protein with the capacity to both bind specifically to small RNA molecules (si-RNA) and mediate in the cell-to-cell movement of such siRNA. Importantly, studies conducted with support from this DOE program also yielded a detailed characterization of the first phloem-mobile RNP complex isolated from pumpkin, namely the CmRBP50-RNP complex. This RNP complex was shown to bind, in a sequence-specific manner, to a set of transcripts encoding for transcription factors. The remarkable stability of this CmRBP50-RNP complex allows for long-distance delivery of bound transcripts from mature leaves into developing tissues and organs. Knowledge gained from this project can be used to exert control over the long-distance signaling networks used by plants to integrate their physiological and developmental programs at a whole plant level. Eventually, this

  18. Investigation of the optical properties of novel organic macromolecules for solar cell applications

    Science.gov (United States)

    Adegoke, Oluwasegun Oluwasina

    The search for renewable energy sources to replace fossil fuel has been a major research focus in the energy sector. The sun, with its vast amount of energy, remains the most abundant and ubiquitous energy source that far exceeds the world energy demand. The ability to effectively capture and convert energy from the sun in the form of photons will be the key to its effective utilization. Organic macromolecules have tremendous potentials to replace and out-perform existing materials, due to their low-cost, ease of tunability, high absorption coefficient and "green" nature. In this dissertation, spectroscopic techniques of steady state absorption and time-resolved fluorescence spectroscopy were used to show the improved absorption of the oligothiophene-functionalized ZnPc through ultrafast energy transfer. ZnPc is known for its chemical and thermal stability. The power conversion efficiency (PCE) in ZnPc-based solar devices is however, very low because of the poor absorption of ZnPc in the 300 - 550 nm region of the solar spectrum. Oligothiophenes have good absorption in the spectral region where the absorption of ZnPc is poor. Other groups of organic compounds that have gained prominence in the study for the design of efficient active materials for photovoltaic cells are the polymers. In the dissertation, different factors which can affect the performance of organic polymers in photovoltaics systems were investigated and analyzed. The effects of the alteration of conjugation, donor-acceptor groups, heteroatoms and alkyl side chains on the photophysical properties and ultimately the performance of organic polymers in organic photovoltaics were investigated. The different effects were investigated using ultrafast spectroscopic techniques which are capable of providing insight of fluorescence decay dynamics at very short times in a time scale of femtosecond. The electronic structure calculations of the polymers were carried out to provide further evidence to the

  19. Stellate macroporous silica nanospheres in bio-macromolecules encapsulation and delivery

    Science.gov (United States)

    Chi, Hao-Hsin

    This project focused on using mesoporous silica as a solid support to encapsulate enzymes for operating a highly economic, and recyclable biomass processing system. The main objective is to turn non-food biomass sources into food products. Enzymes are macromolecules with the structural backbone of proteins or ribonucleic acid sequences (RNAs) which work as catalysts in living organisms. Enzymes have the advantage of being the least contaminating catalyst due to normal catalyst might generate toxic by-product, and preferable to organic and inorganic catalysts, especially when used for product related to human used, which require biocompatibility of final product. However, there are several disadvantages in enzyme utilization. Their fabrication is time-consuming and requires elaborated molecular biology processes. Most of the enzymes need well-defined reaction conditions to be functional and operate at high yield. Unfortunately, although they are reusable as normal catalysts, it proves difficult to extract or reuse the enzymes from a reaction. Also, enzyme molecules are easily degradable and demand proper storage. To overcome some of the disadvantages, especially regarding stability to degradation, recovery, and reusability, immobilization of enzyme on solid support has become a thriving methodology. In recent years, mesoporous silica nanomaterials(MSN) have been at the forefront of enzyme immobilization given their extensive surface area, which provides capability to increase enzyme loading and for their demonstrate ability to protect enzyme from degradation, thus enabling high recyclability. Mesoporous silica is biocompatible and has already been used for several applications included. Catalysis, drug delivery, and Bio-imaging. Previously published research utilized mesoporous silica to deliver drugs, DNAs, RNAs or encapsulate single enzyme. The objective of this research is completed to develop a new porous silica platform that is unique in its porosity structure

  20. Effects of Purification on the Crystallization of Lysozyme

    Science.gov (United States)

    Ewing, Felecia L.; Forsythe, Elizabeth L.; Van Der Woerd, Mark; Pusey, Marc L.

    1996-01-01

    We have additionally purified a commercial lysozyme preparation by cation exchange chromatography, followed by recrystallization. This material is 99.96% pure with respect to macromolecular impurities. At basic pH, the purified lysozyme gave only tetragonal crystals at 20 C. Protein used directly from the bottle, prepared by dialysis against distilled water, or which did not bind to the cation exchange column had considerably altered crystallization behavior. Lysozyme which did not bind to the cation exchange column was subsequently purified by size exclusion chromatography. This material gave predominately bundles of rod-shaped crystals with some small tetragonal crystals at lower pHs. The origin of the bundled rod habit was postulated to be a thermally dependent tetragonal- orthorhombic change in the protein structure. This was subsequently ruled out on the basis of crystallization behavior and growth rate experiments. This suggests that heterogeneous forms of lysozyme may be responsible. These results demonstrate three classes of impurities: (1) small molecules, which may be removed by dialysis; (2) macromolecules, which are removable by chromatographic techniques; and (3) heterogeneous forms of the protein, which can be removed in this case by cation exchange chromatography. Of these, heterogeneous forms of the lysozyme apparently have the greatest affect on its crystallization behavior.

  1. Improved crystal quality of a-plane GaN with high- temperature 3-dimensional GaN buffer layers deposited by using metal-organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Park, Sung Hyun; Moon, Dae Young; Kim, Bum Ho; Kim, Dong Uk; Chang, Ho Jun; Jeon, Heon Su; Yoon, Eui Joon; Joo, Ki Su; You, Duck Jae; Nanishi, Yasushi

    2012-01-01

    a-plane GaN on r-plane sapphire substrates suffers from high density defects and rough surfaces. To obtain pit-free a-plane GaN by metal-organic chemical vapor deposition, we intentionally grew high-temperature (HT) 3-dimensional (3D) GaN buffer layers on a GaN nucleation layer. The effects of the HT 3D GaN buffer layers on crystal quality and the surface morphology of a-plane GaN were studied. The insertion of a 3D GaN buffer layer with an optimum thickness was found to be an effective method to obtain pit-free a-plane GaN with improved crystalline quality on r-plane sapphire substrates. An a-plane GaN light emitting diode (LED) at an emission wavelength around 480 nm with negligible peak shift was successfully fabricated.

  2. Magnetophotonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, M [Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Fujikawa, R [Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Baryshev, A [Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Khanikaev, A [Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Lim, P B [CREST, Japan Science and Technology Agency, Saitama 332-0012, Japan (Japan); Uchida, H [Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Aktsipetrov, O [Lomonosov Moscow State University, Leninskie Gory, Moscow, 119992 (Russian Federation); Fedyanin, A [Lomonosov Moscow State University, Leninskie Gory, Moscow, 119992 (Russian Federation); Murzina, T [Lomonosov Moscow State University, Leninskie Gory, Moscow, 119992 (Russian Federation); Granovsky, A [Lomonosov Moscow State University, Leninskie Gory, Moscow, 119992 (Russian Federation)

    2006-04-21

    When the constitutive materials of photonic crystals (PCs) are magnetic, or even only a defect introduced in PCs is magnetic, the resultant PCs exhibit very unique optical and magneto-optical properties. The strong photon confinement in the vicinity of magnetic defects results in large enhancement in linear and nonlinear magneto-optical responses of the media. Novel functions, such as band Faraday effect, magnetic super-prism effect and non-reciprocal or magnetically controllable photonic band structure, are predicted to occur theoretically. All the unique features of the media arise from the existence of magnetization in media, and hence they are called magnetophotonic crystals providing the spin-dependent nature in PCs. (topical review)

  3. Magnetophotonic crystals

    International Nuclear Information System (INIS)

    Inoue, M; Fujikawa, R; Baryshev, A; Khanikaev, A; Lim, P B; Uchida, H; Aktsipetrov, O; Fedyanin, A; Murzina, T; Granovsky, A

    2006-01-01

    When the constitutive materials of photonic crystals (PCs) are magnetic, or even only a defect introduced in PCs is magnetic, the resultant PCs exhibit very unique optical and magneto-optical properties. The strong photon confinement in the vicinity of magnetic defects results in large enhancement in linear and nonlinear magneto-optical responses of the media. Novel functions, such as band Faraday effect, magnetic super-prism effect and non-reciprocal or magnetically controllable photonic band structure, are predicted to occur theoretically. All the unique features of the media arise from the existence of magnetization in media, and hence they are called magnetophotonic crystals providing the spin-dependent nature in PCs. (topical review)

  4. Effect of vitamin A deficiency on permeability of the small intestinal mucosa for macromolecules in adult rats

    International Nuclear Information System (INIS)

    Gmoshinskii, I.V.; Khvylya, S.I.; Kon', I.Ya.

    1987-01-01

    The authors study the effect of experimental vitamin A deficiency on absorption of macromolecules of hen's ovalbumin in the intestine. An electron-microscopic study of permeability of small intestine enterocytes for particles of colloidal lanthanum hydroxide La(OH) 3 was carried out at the same time. The concentration of unsplit hen's ovalbumin in the blood of the rats used in the experiment was determined by competitive radioimmunoassay. Samples of serum were incubated with indicator doses of 125 I-OA. Radioactivity of the precipitates was measured

  5. Image processing of small protein-crystals in electron microscopy

    International Nuclear Information System (INIS)

    Feinberg, D.A.

    1978-11-01

    This electron microscope study was undertaken to determine whether high resolution reconstructed images could be obtained from statistically noisy micrographs by the super-position of several small areas of images of well-ordered crystals of biological macromolecules. Methods of rotational and translational alignment which use Fourier space data were demonstrated to be superior to methods which use Real space image data. After alignment, the addition of the diffraction patterns of four small areas did not produce higher resolution because of unexpected image distortion effects. A method was developed to determine the location of the distortion origin and the coefficients of spiral distortion and pincushion/barrel distortion in order to make future correction of distortions in electron microscope images of large area crystals

  6. Growth and Characterization of ZnTe Crystal

    International Nuclear Information System (INIS)

    Nann Thazin

    2011-12-01

    High quality ZnTe crystals have been synthesized by vapor Transport method. The grown crystals were p-type. The concentration and mobility were 2.5 x 10 16 cm-3 and 23 cm2/Vs at 300K, according to Hall effect measurements. Surface morphology of the crystal was investigated by scanning electron microscope (SEM). Crystal orientation and lattice parameters of the crystals were also analysed by XRD. From X-ray diffraction studies the structure of the grown crystals were found to be zinc-blende. The crystal emitted light in the visible range at room temperature.

  7. The MORPHEUS II protein crystallization screen

    International Nuclear Information System (INIS)

    Gorrec, Fabrice

    2015-01-01

    MORPHEUS II is a 96-condition initial crystallization screen formulated de novo. The screen incorporates reagents selected from the Protein Data Bank to yield crystals that are not observed in traditional conditions. In addition, the formulation facilitates the optimization and cryoprotection of crystals. High-quality macromolecular crystals are a prerequisite for the process of protein structure determination by X-ray diffraction. Unfortunately, the relative yield of diffraction-quality crystals from crystallization experiments is often very low. In this context, innovative crystallization screen formulations are continuously being developed. In the past, MORPHEUS, a screen in which each condition integrates a mix of additives selected from the Protein Data Bank, a cryoprotectant and a buffer system, was developed. Here, MORPHEUS II, a follow-up to the original 96-condition initial screen, is described. Reagents were selected to yield crystals when none might be observed in traditional initial screens. Besides, the screen includes heavy atoms for experimental phasing and small polyols to ensure the cryoprotection of crystals. The suitability of the resulting novel conditions is shown by the crystallization of a broad variety of protein samples and their efficiency is compared with commercially available conditions

  8. The MORPHEUS II protein crystallization screen

    Energy Technology Data Exchange (ETDEWEB)

    Gorrec, Fabrice, E-mail: fgorrec@mrc-lmb.cam.ac.uk [MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH (United Kingdom)

    2015-06-27

    MORPHEUS II is a 96-condition initial crystallization screen formulated de novo. The screen incorporates reagents selected from the Protein Data Bank to yield crystals that are not observed in traditional conditions. In addition, the formulation facilitates the optimization and cryoprotection of crystals. High-quality macromolecular crystals are a prerequisite for the process of protein structure determination by X-ray diffraction. Unfortunately, the relative yield of diffraction-quality crystals from crystallization experiments is often very low. In this context, innovative crystallization screen formulations are continuously being developed. In the past, MORPHEUS, a screen in which each condition integrates a mix of additives selected from the Protein Data Bank, a cryoprotectant and a buffer system, was developed. Here, MORPHEUS II, a follow-up to the original 96-condition initial screen, is described. Reagents were selected to yield crystals when none might be observed in traditional initial screens. Besides, the screen includes heavy atoms for experimental phasing and small polyols to ensure the cryoprotection of crystals. The suitability of the resulting novel conditions is shown by the crystallization of a broad variety of protein samples and their efficiency is compared with commercially available conditions.

  9. Detection of site-specific binding and co-binding of ligands to macromolecules using 19F NMR

    International Nuclear Information System (INIS)

    Jenkins, B.G.

    1991-01-01

    Study of ligand-macromolecular interactions by 19 F nuclear magnetic resonance (NMR) spectroscopy affords many opportunities for obtaining molecular biochemical and pharmaceutical information. This is due to the absence of a background fluorine signal, as well as the relatively high sensitivity of 19 F NMR. Use of fluorine-labeled ligands enables one to probe not only binding and co-binding phenomena to macromolecules, but also can provide data on binding constants, stoichiometries, kinetics, and conformational properties of these complexes. Under conditions of slow exchange and macromolecule-induced chemical shifts, multiple 19 F NMR resonances can be observed for free and bound ligands. These shifted resonances are a direct correlate of the concentration of ligand bound in a specific state rather than the global concentrations of bound or free ligand which are usually determined using other techniques such as absorption spectroscopy or equilibrium dialysis. Examples of these interactions are demonstrated both from the literature and from interactions of 5-fluorotryptophan, 5-fluorosalicylic acid, flurbiprofen, and sulindac sulfide with human serum albumin. Other applications of 19 F NMR to study of these interactions in vivo, as well for receptor binding and metabolic tracing of fluorinated drugs and proteins are discussed

  10. Synthesis and evaluation of macromolecule-bound derivatives of a peptidyl-1-beta-D-arabinofuranosylcytosine prodrug.

    Science.gov (United States)

    Balajthy, Zoltan

    2008-04-01

    Macromolecule-bound Val-Leu-Lys-ara-C (1) prodrugs were synthesized with spacers (-HN-(CH(2))(x)-CO-; x =1,3,5) between the dextran carrier (T-70) and 1, in order to achieve a sustained-release drug delivery system dextran-NH-(CH(2))(x:1,3,5)-CO-Val-Leu-Lys-ara-C (5, 6 and 7). The conjugation increased the stability of 1 in aqueous buffer solutions by three times (t((1/2)) 53.0 h, pH 7.4). The length of spacer also regulated the rate of hydrolysis of the prodrugs in serum. The shortest spacer (-HN-(CH(2))-CO-, (2)) in 5 provided the best protection of 1 against the hydrolyzing ability of proteinase- alpha(2)-macroglobulin complexes, increasing its half-life approximately 30-fold. The conjugation procedure resulted in a growth arrest ability for macromolecular-bound prodrugs 5, 6 and 7 against L1210 with IC(50) of 0.01 microM in vitro, which is significantly lower than that of other ara-C-macromolecule conjugates. 5 and 6 arrested cell growth in a broader range of concentration, between 1 x 10(-5)-1.0 microM, than ara-C could.

  11. Microvillus-Specific Protein Tyrosine Phosphatase SAP-1 Plays a Role in Regulating the Intestinal Paracellular Transport of Macromolecules.

    Science.gov (United States)

    Mori, Shingo; Kamei, Noriyasu; Murata, Yoji; Takayama, Kozo; Matozaki, Takashi; Takeda-Morishita, Mariko

    2017-09-01

    The stomach cancer-associated protein tyrosine phosphatase 1 (SAP-1) is a receptor-type protein tyrosine phosphatase that is specifically expressed on the apical membrane of the intestinal epithelium. SAP-1 is known to maintain the balance of phosphorylation of proteins together with protein kinases; however, its biological function and impact on pharmacokinetics in the intestine remain unclear. The present study, therefore, aimed at clarifying the relationship between SAP-1 and the intestinal absorption behaviors of typical transporter substrates and macromolecules. The endogenous levels of glucose and total cholesterol in the blood were similar between wild-type and SAP-1-deficient mice (Sap1 -/- ), suggesting no contribution of SAP-1 to biogenic influx. Moreover, in vitro transport study with everted ileal sacs demonstrated that there was no difference in the absorption of breast cancer resistance protein, P-glycoprotein, and peptide transporter substrates between both mice. However, absorptive clearance of macromolecular model dextrans (FD-4 and FD-10) in Sap1 -/- mice was significantly higher than that in wild-type mice, and this was confirmed by the trend of increased FD-4 absorption from colonic loops of Sap1 -/- mice. Therefore, the results of this study suggest the partial contribution of SAP-1 to the regulated transport of hydrophilic macromolecules through paracellular tight junctions. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  12. Elevated uptake of plasma macromolecules by regions of arterial wall predisposed to plaque instability in a mouse model.

    Directory of Open Access Journals (Sweden)

    Zahra Mohri

    Full Text Available Atherosclerosis may be triggered by an elevated net transport of lipid-carrying macromolecules from plasma into the arterial wall. We hypothesised that whether lesions are of the thin-cap fibroatheroma (TCFA type or are less fatty and more fibrous depends on the degree of elevation of transport, with greater uptake leading to the former. We further hypothesised that the degree of elevation can depend on haemodynamic wall shear stress characteristics and nitric oxide synthesis. Placing a tapered cuff around the carotid artery of apolipoprotein E -/- mice modifies patterns of shear stress and eNOS expression, and triggers lesion development at the upstream and downstream cuff margins; upstream but not downstream lesions resemble the TCFA. We measured wall uptake of a macromolecular tracer in the carotid artery of C57bl/6 mice after cuff placement. Uptake was elevated in the regions that develop lesions in hyperlipidaemic mice and was significantly more elevated where plaques of the TCFA type develop. Computational simulations and effects of reversing the cuff orientation indicated a role for solid as well as fluid mechanical stresses. Inhibiting NO synthesis abolished the difference in uptake between the upstream and downstream sites. The data support the hypothesis that excessively elevated wall uptake of plasma macromolecules initiates the development of the TCFA, suggest that such uptake can result from solid and fluid mechanical stresses, and are consistent with a role for NO synthesis. Modification of wall transport properties might form the basis of novel methods for reducing plaque rupture.

  13. Photonic time crystals.

    Science.gov (United States)

    Zeng, Lunwu; Xu, Jin; Wang, Chengen; Zhang, Jianhua; Zhao, Yuting; Zeng, Jing; Song, Runxia

    2017-12-07

    When space (time) translation symmetry is spontaneously broken, the space crystal (time crystal) forms; when permittivity and permeability periodically vary with space (time), the photonic crystal (photonic time crystal) forms. We proposed the concept of photonic time crystal and rewritten the Maxwell's equations. Utilizing Finite Difference Time Domain (FDTD) method, we simulated electromagnetic wave propagation in photonic time crystal and photonic space-time crystal, the simulation results show that more intensive scatter fields can obtained in photonic time crystal and photonic space-time crystal.

  14. Electron transfer behaviour of biological macromolecules towards the single-molecule level

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Grubb, Mikala; Hansen, Allan Glargaard

    2003-01-01

    is combined with state-of-the-art physical electrochemistry with emphasis on single-crystal, atomically planar electrode surfaces, in situ scanning tunnelling microscopy (STM) and other surface techniques. These approaches have brought bioelectrochemistry important steps forward towards the nanoscale...... and single-molecule levels.We discuss here these advances with reference to two specific redox metalloproteins, the blue single-copper protein Pseudomonas aeruginosa azurin and the single-haem protein Saccharomyces cerevisiae yeast cytochrome c, and a short oligonucleotide. Both proteins can be immobilized...... electron transfer (ET) function retained. In situ STM can also address the microscopic mechanisms for electron tunnelling through the biomolecules and offers novel notions such as coherent multi-ET between the substrate and tip via the molecular redox levels. This differs in important respects from...

  15. Pressure-induced melting of micellar crystal

    DEFF Research Database (Denmark)

    Mortensen, K.; Schwahn, D.; Janssen, S.

    1993-01-01

    that pressure improves the solvent quality of water, thus resulting in decomposition of the micelles and consequent melting of the micellar crystal. The combined pressure and temperature dependence reveals that in spite of the apparent increase of order on the 100 angstrom length scale upon increasing......Aqueous solutions of triblock copolymers of poly(ethylene oxide) and poly(propylene oxide) aggregate at elevated temperatures into micelles which for polymer concentrations greater-than-or-equal-to 20% make a hard sphere crystallization to a cubic micellar crystal. Structural studies show...... temperature (decreasing pressure) the overall entropy increases through the inverted micellar crystallization characteristic....

  16. Preparation of high magneto-optical performance and crystalline quality Ce{sub 1}Gd{sub 2}Fe{sub 5−x}Ga{sub x}O{sub 12} films on CLNGG substrate crystal

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Qiu-ping; Zheng, Ze-yuan; Lin, Nan-xi; Liu, Xiao-feng; Hong, Can-huang; Hu, Xiao-lin, E-mail: linamethyst@fzu.edu.cn; Zhuang, Nai-feng; Chen, Jian-zhong, E-mail: j.z.chen@fzu.edu.cn

    2016-11-01

    Thin films of Ce{sub 1}Gd{sub 2}Fe{sub 5−x}Ga{sub x}O{sub 12} (Ce,Ga:GIG) were prepared on Gd{sub 3}Ga{sub 5}O{sub 12} (GGG) and Ca{sub 2.90}Li{sub 0.30}Nb{sub 1.93}Ga{sub 2.76}O{sub 12} (CLNGG) substrates by using radio frequency magnetron sputtering technique. The phase, grain orientation, surface morphology, transmittance, magnetism and magnetic circular dichroism (MCD) properties of films were analyzed. And the effects of lattice mismatch and non-magnetic Ga{sup 3+}-doping were discussed. The results show that the films with higher crystallized quality and lower stress can be obtained by growing on CLNGG than on GGG. Moreover, the coercive force, magnetization, magneto-optical effect intensity and orientation of film can be effectively regulated by adjusting Ga{sup 3+}-doped concentration. - Highlights: • With excellent magneto-optical performance, Ce,Ga:GIG film has a good application prospect. • Ce,Ga:GIG film with high quality were prepared on CLNGG by RF magnetron sputtering. • Crystalline quality and morphology of films are intently related to the substrate. • Ga{sup 3+} doping obviously affect on magnetism and magneto-optical property of Ce:GIG film.

  17. Correlation Between Two-Dimensional Electron Gas Mobility and Crystal Quality in AlGaN/GaN High-Electron-Mobility Transistor Structure Grown on 4H-SiC.

    Science.gov (United States)

    Heo, Cheon; Jang, Jongjin; Lee, Kyngjae; So, Byungchan; Lee, Kyungbae; Ko, Kwangse; Nam, Okhyun

    2017-01-01

    We investigated the correlation between the crystal quality and two-dimensional electron gas (2DEG) mobility of an AlGaN/GaN high-electron-mobility transistor (HEMT) structure grown by metal-organic chemical vapor deposition. For the structure with an AlN nucleation layer grown at 1100 °C, the 2DEG mobility and sheet carrier density were 1627 cm²/V·s and 3.23 × 10¹³ cm⁻², respectively, at room temperature. Further, it was confirmed that the edge dislocation density of the GaN buffer layer was related to the 2DEG mobility and sheet carrier density in the AlGaN/GaN HEMT.

  18. Protein crystal nucleation in pores.

    Science.gov (United States)

    Nanev, Christo N; Saridakis, Emmanuel; Chayen, Naomi E

    2017-01-16

    The most powerful method for protein structure determination is X-ray crystallography which relies on the availability of high quality crystals. Obtaining protein crystals is a major bottleneck, and inducing their nucleation is of crucial importance in this field. An effective method to form crystals is to introduce nucleation-inducing heterologous materials into the crystallization solution. Porous materials are exceptionally effective at inducing nucleation. It is shown here that a combined diffusion-adsorption effect can increase protein concentration inside pores, which enables crystal nucleation even under conditions where heterogeneous nucleation on flat surfaces is absent. Provided the pore is sufficiently narrow, protein molecules approach its walls and adsorb more frequently than they can escape. The decrease in the nucleation energy barrier is calculated, exhibiting its quantitative dependence on the confinement space and the energy of interaction with the pore walls. These results provide a detailed explanation of the effectiveness of porous materials for nucleation of protein crystals, and will be useful for optimal design of such materials.

  19. Hydrothermal Growth of Polyscale Crystals

    Science.gov (United States)

    Byrappa, Kullaiah

    In this chapter, the importance of the hydrothermal technique for growth of polyscale crystals is discussed with reference to its efficiency in synthesizing high-quality crystals of various sizes for modern technological applications. The historical development of the hydrothermal technique is briefly discussed, to show its evolution over time. Also some of the important types of apparatus used in routine hydrothermal research, including the continuous production of nanosize crystals, are discussed. The latest trends in the hydrothermal growth of crystals, such as thermodynamic modeling and understanding of the solution chemistry, are elucidated with appropriate examples. The growth of some selected bulk, fine, and nanosized crystals of current technological significance, such as quartz, aluminum and gallium berlinites, calcite, gemstones, rare-earth vanadates, electroceramic titanates, and carbon polymorphs, is discussed in detail. Future trends in the hydrothermal technique, required to meet the challenges of fast-growing demand for materials in various technological fields, are described. At the end of this chapter, an Appendix 18.A containing a more or less complete list of the characteristic families of crystals synthesized by the hydrothermal technique is given with the solvent and pressure-temperature (PT) conditions used in their synthesis.

  20. Photonic Crystal Fibers

    National Research Council Canada - National Science Library

    Kristiansen, Rene E

    2005-01-01

    This report results from a contract tasking Crystal Fibre A/S as follows: Crystal Fibre will conduct research and development of large mode area, dual clad multi-core Yb-doped photonic crystal fiber...

  1. DKDP crystal growth controlled by cooling rate

    Science.gov (United States)

    Xie, Xiaoyi; Qi, Hongji; Shao, Jianda

    2017-08-01

    The performance of deuterated potassium dihydrogen phosphate (DKDP) crystal directly affects beam quality, energy and conversion efficiency in the Inertial Confinement Fusion(ICF)facility, which is related with the initial saturation temperature of solution and the real-time supersaturation during the crystal growth. However, traditional method to measure the saturation temperature is neither efficient nor accurate enough. Besides, the supersaturation is often controlled by experience, which yields the higher error and leads to the instability during the crystal growth. In this paper, DKDP solution with 78% deuteration concentration is crystallized in different temperatures. We study the relation between solubility and temperature of DKDP and fit a theoretical curve with a parabola model. With the model, the measurement of saturation temperature is simplified and the control precision of the cooling rate is improved during the crystal growth, which is beneficial for optimizing the crystal growth process.

  2. Macromolecular crystallization in microgravity generated by a superconducting magnet.

    Science.gov (United States)

    Wakayama, N I; Yin, D C; Harata, K; Kiyoshi, T; Fujiwara, M; Tanimoto, Y

    2006-09-01

    About 30% of the protein crystals grown in space yield better X-ray diffraction data than the best crystals grown on the earth. The microgravity environments provided by the application of an upward magnetic force constitute excellent candidates for simulating the microgravity conditions in space. Here, we describe a method to control effective gravity and formation of protein crystals in various levels of effective gravity. Since 2002, the stable and long-time durable microgravity generated by a convenient type of superconducting magnet has been available for protein crystal growth. For the first time, protein crystals, orthorhombic lysozyme, were grown at microgravity on the earth, and it was proved that this microgravity improved the crystal quality effectively and reproducibly. The present method always accompanies a strong magnetic field, and the magnetic field itself seems to improve crystal quality. Microgravity is not always effective for improving crystal quality. When we applied this microgravity to the formation of cubic porcine insulin and tetragonal lysozyme crystals, we observed no dependence of effective gravity on crystal quality. Thus, this kind of test will be useful for selecting promising proteins prior to the space experiments. Finally, the microgravity generated by the magnet is compared with that in space, considering the cost, the quality of microgravity, experimental convenience, etc., and the future use of this microgravity for macromolecular crystal growth is discussed.

  3. Exploring the structure of biological macromolecules in solution using Quokka, the small angle neutron scattering instrument, at ANSTO

    International Nuclear Information System (INIS)

    Wood, Kathleen; Jeffries, Cy M.; Knott, Robert B.; Sokolova, Anna; Jacques, David A.; Duff, Anthony P.

    2015-01-01

    Small angle neutron scattering (SANS) is widely used to extract structural parameters, shape and other types of information from a vast array of materials. The technique is applied to biological macromolecules and their complexes in solution to reveal information often not accessible by other techniques. SANS measurements on biomolecules present some particular challenges however, one of which is suitable instrumentation. This review details SANS experiments performed on two well-characterised globular proteins (lysozyme and glucose isomerase) using Quokka, the recently commissioned SANS instrument at the Australian Nuclear Science and Technology Organisation (ANSTO). The instrument configuration as well as data collection and reduction strategies for biological investigations are discussed and act as a general reference for structural biologists who use the instrument. Both model independent analysis of the two proteins and ab initio modelling illustrate that Quokka-SANS data can be used to successfully model the overall shapes of proteins in solution, providing a benchmark for users

  4. From the Cover: Microfabricated needles for transdermal delivery of macromolecules and nanoparticles: Fabrication methods and transport studies

    Science.gov (United States)

    McAllister, Devin V.; Wang, Ping M.; Davis, Shawn P.; Park, Jung-Hwan; Canatella, Paul J.; Allen, Mark G.; Prausnitz, Mark R.

    2003-11-01

    Arrays of micrometer-scale needles could be used to deliver drugs, proteins, and particles across skin in a minimally invasive manner. We therefore developed microfabrication techniques for silicon, metal, and biodegradable polymer microneedle arrays having solid and hollow bores with tapered and beveled tips and feature sizes from 1 to 1,000 μm. When solid microneedles were used, skin permeability was increased in vitro by orders of magnitude for macromolecules and particles up to 50 nm in radius. Intracellular delivery of molecules into viable cells was also achieved with high efficiency. Hollow microneedles permitted flow of microliter quantities into skin in vivo, including microinjection of insulin to reduce blood glucose levels in diabetic rats. transdermal drug delivery | skin | microelectromechanical systems | solid microneedle | hollow needle injection

  5. Crystallization of carbohydrate oxidase from Microdochium nivale

    International Nuclear Information System (INIS)

    Dušková, Jarmila; Dohnálek, Jan; Skálová, Tereza; Østergaard, Lars Henrik; Fuglsang, Claus Crone; Kolenko, Petr; Štěpánková, Andrea; Hašek, Jindřich

    2009-01-01

    Industrially used carbohydrate oxidase was successfully crystallized in several forms, diffraction data suitable for structural analysis were collected. Microdochium nivale carbohydrate oxidase was produced by heterologous recombinant expression in Aspergillus oryzae, purified and crystallized. The enzyme crystallizes with varying crystal morphologies depending on the crystallization conditions. Several different crystal forms were obtained using the hanging-drop vapour-diffusion method, two of which were used for diffraction measurements. Hexagon-shaped crystals (form I) diffracted to 2.66 Å resolution, with unit-cell parameters a = b = 55.7, c = 610.4 Å and apparent space group P6 2 22. Analysis of the data quality showed almost perfect twinning of the crystals. Attempts to solve the structure by molecular replacement did not give satisfactory results. Recently, clusters of rod-shaped crystals (form II) were grown in a solution containing PEG MME 550. These crystals belonged to the monoclinic system C2, with unit-cell parameters a = 132.9, b = 56.6, c = 86.5 Å, β = 95.7°. Data sets were collected to a resolution of 2.4 Å. The structure was solved by the molecular-replacement method. Model refinement is currently in progress

  6. Micropore surface area of alkali-soluble plant macromolecules (humic acids) drives their decomposition rates in soil.

    Science.gov (United States)

    Papa, Gabriella; Spagnol, Manuela; Tambone, Fulvia; Pilu, Roberto; Scaglia, Barbara; Adani, Fabrizio

    2010-02-01

    Previous studies suggested that micropore surface area (MSA) of alkali-soluble bio-macromolecules of aerial plant residues of maize constitutes an important factor that explains their humification in soil, that is, preservation against biological degradation. On the other hand, root plant residue contributes to the soil humus balance, as well. Following the experimental design used in a previous paper published in this journal, this study shows that the biochemical recalcitrance of the alkali-soluble acid-insoluble fraction of the root plant material, contributed to the root maize humification of both Wild-type maize plants and its corresponding mutant brown midrib (bm3), this latter characterized by reduced lignin content. Humic acids (HAs) existed in root (root-HAs) were less degraded in soil than corresponding HAs existed in shoot (shoot-HAs): shoot-HAs bm3 (48%)>shoot-HAs Wild-type (37%)>root-HAs Wild-type (33%)>root-HAs bm3 (22%) (degradability shown in parenthesis). These differences were related to the MSA of HAs, that is, root-HAs having a higher MSA than shoot-HAs: shoot-HAs bm3 (41.43+/-1.2m(2)g(-1))macromolecules recalcitrance in soil.

  7. Preparation, definition and stabilisation of an inorganic sol by an organic macromolecule: case of an aluminium hydroxide colloid

    International Nuclear Information System (INIS)

    Hurbin-Faucon, A.

    1966-01-01

    An attempt has been made in this work to define an aluminium colloid which is resistant as a high ionic force and to analyse, in the case of this system, the possibilities. and the limits of certain techniques used in the physical chemistry of colloids. The aluminium colloid is obtained by peptization of an aluminium hydroxide precipitate. The physical characterisation of the micelle is effected using the light scattering method which makes it possible to define the colloid from the point of view of size and shape. An interesting characteristic, arising from the low refractive index of the colloid studied, has led us to use not only the general MIE methods but also the methods normally used in macro-molecular chemistry; these latter involve fewer hypotheses and thus make it possible to carry out a more complete analysis of the sol. Since the aluminium hydroxide colloid is sensitive to a high ionic force, we have begun to study the possibility of making it more stable by means of a macromolecule: gelatin. After characterizing this macromolecule by means of potentiometric and light scattering measurements, we have shown the existence of a chemical interaction which occurs when aluminium hydroxide is brought into contact with gelatin; this interaction leads to the production of an inorganic-organic entity which is stable when the ionic force increases. We have established some of the characteristics of the complex thus formed, in particular the pH range of the solution necessary for its formation, its stability. in the presence of electrolytes and some hypotheses concerning its size and shape, Finally we have tried to define the influence of. the molecular weight and the respective dimensions of each constituent on the formation of the complex and thus on the stabilization. (author) [fr

  8. Facile synthesis of CuSe nanoparticles and high-quality single-crystal two-dimensional hexagonal nanoplatelets with tunable near-infrared optical absorption

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yimin [State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Korolkov, Ilia [Laboratory of Glasses and Ceramics, Institute of Chemistry, CNRS-Université de Rennes I, Campus de Beaulieu, 35042 Rennes Cedex (France); Qiao, Xvsheng [State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Zhang, Xianghua [Laboratory of Glasses and Ceramics, Institute of Chemistry, CNRS-Université de Rennes I, Campus de Beaulieu, 35042 Rennes Cedex (France); Wan, Jun; Fan, Xianping [State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2016-06-15

    A rapid injection approach is used to synthesize the copper selenide nanoparticles and two-dimensional single crystal nanoplates. This technique excludes the use of toxic or expensive materials, increasing the availability of two-dimensional binary chalcogenide semiconductors. The structure of the nanocrystals has been studied and the possible formation mechanism of the nanoplates has been proposed. The optical absorption showed that the nanoplates demonstrated wide and tuneable absorption band in the visible and near infrared region. These nanoplates could be interesting for converting solar energy and for nanophotonic devices operating in the near infrared. - Graphical abstract: TEM images of the copper selenides nanoparticles and nanoplates synthesized at 180 °C for 0 min, 10 min, 60 min. And the growth mechanism of the copper selenide nanoplates via the “oriented attachment”. Display Omitted - Highlights: • CuSe nanoparticles and nanoplates are synthesized by a rapid injection approach. • CuSe band gap can be widely tuned simply by modifying the synthesized time. • Al{sup 3+} ions have a significant impact on the growth rate of the nanoplates. • Growth mechanism of the CuSe nanoplates is based on the “oriented attachment”.

  9. Properties of lead tungstate crystals for high-energy physics

    CERN Document Server

    Ippolitov, M S; Burachas, S; Ikonnikov, V; Kuriakin, A; Lebedev, V; Makov, I; Man'ko, V; Nikulin, S P; Nyanin, A; Saveliev, Yu; Tamulaitis, G; Tsvetkov, A A; Vasilev, A; Vinogradov, Yu I

    2004-01-01

    Technology for the mass production of high-quality PbWO//4 (PWO) scintillating crystals is described. Scintillators produced from PWO crystals are intented for the ALICE CERN heavy ion experiment. Light yield, emission and decay time spectra as well as optical transmission of about 3600 crystals (dimensions 22 multiplied by 22 multiplied by 180 mm**3) were measured. Beam-test results of the ALICE PHOS prototype obtained with such PWO crystals are presented.

  10. The chain length of lignan macromolecule from flaxseed hulls is determined by the incorporation of coumaric acid glucosides and ferulic acid glucosides

    NARCIS (Netherlands)

    Struijs, K.; Vincken, J.P.; Doeswijk, T.G.; Voragen, A.G.J.; Gruppen, H.

    2009-01-01

    Lignan macromolecule from flaxseed hulls is composed of secoisolariciresinol diglucoside (SDG) and herbacetin diglucoside (HDG) moieties ester-linked by 3-hydroxy-3-methylglutaric acid (HMGA), and of p-coumaric acid glucoside (CouAG) and ferulic acid glucoside (FeAG) moieties ester-linked directly

  11. Enhancement of crystal homogeneity of protein crystals under application of an external alternating current electric field

    Energy Technology Data Exchange (ETDEWEB)

    Koizumi, H.; Uda, S.; Fujiwara, K.; Nozawa, J. [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577 (Japan); Tachibana, M. [Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, 236-0027 (Japan); Kojima, K. [Department of Education, Yokohama Soei University, 1 Miho-tyou, Midori-ku, Yokohama, 226-0015 (Japan)

    2014-10-06

    X-ray diffraction rocking-curve measurements were performed on tetragonal hen egg white (HEW) lysozyme crystals grown with and without the application of an external alternating current (AC) electric field. The crystal quality was assessed by the full width at half maximum (FWHM) value for each rocking curve. For two-dimensional maps of the FWHMs measured on the 440 and the 12 12 0 reflection, the crystal homogeneity was improved under application of an external electric field at 1 MHz, compared with that without. In particular, the significant improvement of the crystal homogeneity was observed for the 12 12 0 reflection.

  12. Pressure cryocooling protein crystals

    Science.gov (United States)

    Kim, Chae Un [Ithaca, NY; Gruner, Sol M [Ithaca, NY

    2011-10-04

    Preparation of cryocooled protein crystal is provided by use of helium pressurizing and cryocooling to obtain cryocooled protein crystal allowing collection of high resolution data and by heavier noble gas (krypton or xenon) binding followed by helium pressurizing and cryocooling to obtain cryocooled protein crystal for collection of high resolution data and SAD phasing simultaneously. The helium pressurizing is carried out on crystal coated to prevent dehydration or on crystal grown in aqueous solution in a capillary.

  13. Structure of single-chain single crystals of isotactic polystyrene and their radiation resistance

    International Nuclear Information System (INIS)

    Bu Haishan; Cao Jie; Xu Shengyong; Zhang Ze

    1997-01-01

    The structure of the single-chain single crystals of isotactic polystyrene (i-PS) was investigated by electron diffraction (ED) and high resolution electron microscopy (HREM). The nano-scale single-chain single crystals were found to be very stable to electron irradiation. According to the unit cell of i-PS crystals, the reflection rings in ED pattern and the lattice fringes in HREM images could be indexed, but the lower-index diffractions were not found. It is proposed that the single-chain single crystals are very small, thus secondary electrons may be allowed to escape and radiation damage is highly reduced, and that there are less lower-index lattice planes in the single-chain single crystals to provide sufficient diffraction intensity for recording. HREM images can be achieved at room temperature in the case of single-chain single crystals because of its stability to electron irradiation, therefore, this might be a novel experimental approach to the study of crystal structure of macromolecules

  14. Creatine, Glutamine plus Glutamate, and Macromolecules Are Decreased in the Central White Matter of Premature Neonates around Term.

    Directory of Open Access Journals (Sweden)

    Meriam Koob

    Full Text Available Preterm birth represents a high risk of neurodevelopmental disabilities when associated with white-matter damage. Recent studies have reported cognitive deficits in children born preterm without brain injury on MRI at term-equivalent age. Understanding the microstructural and metabolic underpinnings of these deficits is essential for their early detection. Here, we used diffusion-weighted imaging and single-voxel 1H magnetic resonance spectroscopy (MRS to compare brain maturation at term-equivalent age in premature neonates with no evidence of white matter injury on conventional MRI except diffuse excessive high-signal intensity, and normal term neonates. Thirty-two infants, 16 term neonates (mean post-conceptional age at scan: 39.8±1 weeks and 16 premature neonates (mean gestational age at birth: 29.1±2 weeks, mean post-conceptional age at scan: 39.2±1 weeks were investigated. The MRI/MRS protocol performed at 1.5T involved diffusion-weighted MRI and localized 1H-MRS with the Point RESolved Spectroscopy (PRESS sequence. Preterm neonates showed significantly higher ADC values in the temporal white matter (P<0.05, the occipital white matter (P<0.005 and the thalamus (P<0.05. The proton spectrum of the centrum semiovale was characterized by significantly lower taurine/H2O and macromolecules/H2O ratios (P<0.05 at a TE of 30 ms, and reduced (creatine+phosphocreatine/H2O and (glutamine+glutamate/H2O ratios (P<0.05 at a TE of 135 ms in the preterm neonates than in full-term neonates. Our findings indicate that premature neonates with normal conventional MRI present a delay in brain maturation affecting the white matter and the thalamus. Their brain metabolic profile is characterized by lower levels of creatine, glutamine plus glutamate, and macromolecules in the centrum semiovale, a finding suggesting altered energy metabolism and protein synthesis.

  15. Modeling steady-state dynamics of macromolecules in exponential-stretching flow using multiscale molecular-dynamics-multiparticle-collision simulations.

    Science.gov (United States)

    Ghatage, Dhairyasheel; Chatterji, Apratim

    2013-10-01

    We introduce a method to obtain steady-state uniaxial exponential-stretching flow of a fluid (akin to extensional flow) in the incompressible limit, which enables us to study the response of suspended macromolecules to the flow by computer simulations. The flow field in this flow is defined by v(x) = εx, where v(x) is the velocity of the fluid and ε is the stretch flow gradient. To eliminate the effect of confining boundaries, we produce the flow in a channel of uniform square cross section with periodic boundary conditions in directions perpendicular to the flow, but simultaneously maintain uniform density of fluid along the length of the tube. In experiments a perfect elongational flow is obtained only along the axis of symmetry in a four-roll geometry or a filament-stretching rheometer. We can reproduce flow conditions very similar to extensional flow near the axis of symmetry by exponential-stretching flow; we do this by adding the right amounts of fluid along the length of the flow in our simulations. The fluid particles added along the length of the tube are the same fluid particles which exit the channel due to the flow; thus mass conservation is maintained in our model by default. We also suggest a scheme for possible realization of exponential-stretching flow in experiments. To establish our method as a useful tool to study various soft matter systems in extensional flow, we embed (i) spherical colloids with excluded volume interactions (modeled by the Weeks-Chandler potential) as well as (ii) a bead-spring model of star polymers in the fluid to study their responses to the exponential-stretched flow and show that the responses of macromolecules in the two flows are very similar. We demonstrate that the variation of number density of the suspended colloids along the direction of flow is in tune with our expectations. We also conclude from our study of the deformation of star polymers with different numbers of arms f that the critical flow gradient ε

  16. Coupled Photonic Crystal Cavity Array Laser

    DEFF Research Database (Denmark)

    Schubert, Martin

    in the quadratic lattice. Processing techniques are developed and optimized in order fabricate photonic crystals membranes in gallium arsenide with quantum dots as gain medium and in indium gallium arsenide phosphide with quantum wells as gain medium. Several key issues in process to ensure good quality....... The results are in good agreement with standard coupled mode theory. Also a novel type of photonic crystal structure is proposed called lambda shifted cavity which is a twodimensional photonic crystal laser analog of a VCSEL laser. Detailed measurements of the coupled modes in the photonic crystals...... with quantum dots are carried out. In agreement with a simple gain model the structures do not show stimulated emission. The spectral splitting due to the coupling between single cavities as well as arrays of cavities is studied theoretically and experimentally. Lasing is observed for photonic crystal cavity...

  17. Crystal growth, optical properties, and laser operation of Yb3+-doped NYW single crystal

    Science.gov (United States)

    Cheng, Y.; Xu, X. D.; Yang, X. B.; Xin, Z.; Cao, D. H.; Xu, J.

    2009-11-01

    Laser crystal Yb3+-doped NaY(WO4)2 (Yb:NYW) with excellent quality has been grown by Czochralski technique. The rocking curves from (400) plane of as-grown Yb:NYW crystal was measured and the full-width value at half-maximum was 19.92″. The effective segregation coefficients were measured by the X-ray fluorescence method. The polarized absorption spectra and the fluorescence spectra of Yb:NYW crystal were measured at room temperature. The fluorescence decay lifetime of Yb3+ ion in NYW crystal has been investigated. The spectroscopic parameters of Yb:NYW crystal are calculated and compared with those of Yb:YAG crystal. A continuous wave output power of 3.06 W at 1031 nm was obtained with a slope efficiency of 42% by use of diode pumping.

  18. A Study of Biomolecules as Growth Modifiers of Calcium Oxalate Crystals

    Science.gov (United States)

    Kwak, Junha John

    Crystallization processes are ubiquitous in nature, science, and technology. Controlling crystal growth is pivotal in many industries as material properties and functions can be tailored by tuning crystal habits (e.g. size, shape, phase). In biomineralization, organisms exert excellent control over bottom-up synthesis and assembly of inorganic-organic structures (e.g. bones, teeth, exoskeletons). This is made possible by growth modifiers that range from small molecules to macromolecules, such as proteins. Molecular recognition of the mineral phase allows proteins to function as nucleation templates, matrices, and growth inhibitors or promoters. We are interested in taking a biomimetic approach to control crystallization via biomolecular growth modifiers. We investigated calcium oxalate monohydrate (COM), found in plants and kidney stones, as a model system of crystallization. We studied the effects of four common proteins on COM crystallization: bovine serum albumin (BSA), transferrin, lactoferrin, and lysozyme. Through kinetic studies of COM crystallization, we classified BSA and lysozyme as COM growth inhibitor and promoter respectively. Their inhibition and promotion effects were also evident in the macroscopic crystal habit. Through adsorption and microscopy experiments, we showed that BSA exhibits binding specificity for the apical surfaces of macroscopic COM crystals. Lysozyme, on the other, functions via a non-binding mechanism at the surface to accelerate the growth of the apical surfaces. We also synthesized and studied peptides derived from the protein primary sequences to identify putative domains responsible for these inhibition and promotion effects. Collectively, our study of physiologically relevant biomolecules suggests potential roles of COM modifiers in pathological crystallization and helps to develop guidelines for rational design of biomolecular growth modifiers for applications in crystal engineering.

  19. A RP-HPLC method for quantification of diclofenac sodium released from biological macromolecules.

    Science.gov (United States)

    Bhattacharya, Shiv Sankar; Banerjee, Subham; Ghosh, Ashoke Kumar; Chattopadhyay, Pronobesh; Verma, Anurag; Ghosh, Amitava

    2013-07-01

    Interpenetrating network (IPN) microbeads of sodium carboxymethyl locust bean gum (SCMLBG) and sodium carboxymethyl cellulose (SCMC) containing diclofenac sodium (DS), a nonsteroidal anti-inflammatory drug, were prepared by single water-in-water (w/w) emulsion gelation process using AlCl3 as cross-linking agent in a complete aqueous environment. Pharmacokinetic study of these IPN microbeads was then carried out by a simple and feasible high-performance liquid chromatographic method with UV detection which was developed and validated for the quantification of diclofenac sodium in rabbit plasma. The chromatographic separation was carried out in a Hypersil BDS, C18 column (250 mm × 4.6 mm; 5 m). The mobile phase was a mixture of acetonitrile and methanol (70:30, v/v) at a flow rate of 1.0 ml/min. The UV detection was set at 276 nm. The extraction recovery of diclofenac sodium in plasma of three quality control (QC) samples was ranged from 81.52% to 95.29%. The calibration curve was linear in the concentration range of 20-1000 ng/ml with the correlation coefficient (r(2)) above 0.9951. The method was specific and sensitive with the limit of quantification of 20 ng/ml. In stability tests, diclofenac sodium in rabbit plasma was stable during storage and assay procedure. Copyright © 2013. Published by Elsevier B.V.

  20. Enhanced Crystallization by Methanol Additive in Anti-solvent for Achieving High-quality MAPbI3 Perovskite Films in Humid Atmosphere.

    Science.gov (United States)

    Yang, Fu; Kamarudin, Muhammad Akmal; Zhang, PuTao; Kapil, Gaurav; Ma, Tingli; Hayase, Shuzi

    2018-05-04

    Perovskite solar cells have attracted considerable attention owing to easy and low-cost solution manufacturing process with high power conversion efficiency. However, the fabrication process is usually performed inside glovebox to avoid the moisture, as organometallic halide perovskite is easily dissolved in water. In this study, we propose one-step fabrication of high-quality MAPbI3 perovskite films in 50 % RH humid ambient air by using diethyl ether as an anti-solvent and methanol as an additive into this anti-solvent. Because of the existence of methanol, the water molecules can be efficiently removed from the gaps of perovskite precursors and the perovskite film formation can be slightly controlled leading to pinhole-free and low roughness film. Concurrently, methanol can modify a proper DMSO ratio in the intermediate perovskite phase to regulate perovskite formation. Planar solar cells fabricated by using this method exhibited the best efficiency of 16.4 % with a reduced current density-voltage hysteresis. This efficiency value is approximately 160 % higher than the devices fabrication by using only diethyl ether treatment. From the impedance measurement, it is also found that the recombination reaction has been suppressed when the device prepared with additive anti-solvent way. This method presents a new path for controlling the growth and morphology of perovskite films in the humid climates and uncontrolled laboratories. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Method for solid state crystal growth

    Science.gov (United States)

    Nolas, George S.; Beekman, Matthew K.

    2013-04-09

    A novel method for high quality crystal growth of intermetallic clathrates is presented. The synthesis of high quality pure phase crystals has been complicated by the simultaneous formation of both clathrate type-I and clathrate type-II structures. It was found that selective, phase pure, single-crystal growth of type-I and type-II clathrates can be achieved by maintaining sufficient partial pressure of a chemical constituent during slow, controlled deprivation of the chemical constituent from the primary reactant. The chemical constituent is slowly removed from the primary reactant by the reaction of the chemical constituent vapor with a secondary reactant, spatially separated from the primary reactant, in a closed volume under uniaxial pressure and heat to form the single phase pure crystals.

  2. CRYSTALLIZATION IN MULTICOMPONENT GLASSES

    Energy Technology Data Exchange (ETDEWEB)

    KRUGER AA; HRMA PR

    2009-10-08

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  3. Crystallization In Multicomponent Glasses

    International Nuclear Information System (INIS)

    Kruger, A.A.; Hrma, P.R.

    2009-01-01

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  4. The role of the extracellular matrix in tissue distribution of macromolecules in normal and pathological tissues: potential therapeutic consequences.

    Science.gov (United States)

    Wiig, Helge; Gyenge, Christina; Iversen, Per Ole; Gullberg, Donald; Tenstad, Olav

    2008-05-01

    The interstitial space is a dynamic microenvironment that consists of interstitial fluid and structural molecules of the extracellular matrix, such as glycosaminoglycans (hyaluronan and proteoglycans) and collagen. Macromolecules can distribute in the interstitium only in those spaces unoccupied by structural components, a phenomenon called interstitial exclusion. The exclusion phenomenon has direct consequences for plasma volume regulation. Early studies have assigned a major role to collagen as an excluding agent that accounts for the sterical (geometrical) exclusion. More recently, it has been shown that the contribution of negatively charged glycosaminoglycans might also be significant, resulting in an additional electrostatical exclusion effect. This charge effect may be of importance for drug uptake and suggests that either the glycosaminoglycans or the net charge of macromolecular substances to be delivered may be targeted to increase the available volume and uptake of macromolecular therapeutic agents in tumor tissue. Here, we provide an overview of the structural components of the interstitium and discuss the importance the sterical and electrostatical components have on the dynamics of transcapillary fluid exchange.

  5. Analysis of Mammalian Cell Proliferation and Macromolecule Synthesis Using Deuterated Water and Gas Chromatography-Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Victoria C. Foletta

    2016-10-01

    Full Text Available Deuterated water (2H2O, a stable isotopic tracer, provides a convenient and reliable way to label multiple cellular biomass components (macromolecules, thus permitting the calculation of their synthesis rates. Here, we have combined 2H2O labelling, GC-MS analysis and a novel cell fractionation method to extract multiple biomass components (DNA, protein and lipids from the one biological sample, thus permitting the simultaneous measurement of DNA (cell proliferation, protein and lipid synthesis rates. We have used this approach to characterize the turnover rates and metabolism of a panel of mammalian cells in vitro (muscle C2C12 and colon cancer cell lines. Our data show that in actively-proliferating cells, biomass synthesis rates are strongly linked to the rate of cell division. Furthermore, in both proliferating and non-proliferating cells, it is the lipid pool that undergoes the most rapid turnover when compared to DNA and protein. Finally, our data in human colon cancer cell lines reveal a marked heterogeneity in the reliance on the de novo lipogenic pathway, with the cells being dependent on both ‘self-made’ and exogenously-derived fatty acid.

  6. Evanescent wave cavity ring-down spectroscopy (EW-CRDS) as a probe of macromolecule adsorption kinetics at functionalized interfaces.

    Science.gov (United States)

    O'Connell, Michael A; de Cuendias, Anne; Gayet, Florence; Shirley, Ian M; Mackenzie, Stuart R; Haddleton, David M; Unwin, Patrick R

    2012-05-01

    Evanescent wave cavity ring-down spectroscopy (EW-CRDS) has been employed to study the interfacial adsorption kinetics of coumarin-tagged macromolecules onto a range of functionalized planar surfaces. Such studies are valuable in designing polymers for complex systems where the degree of interaction between the polymer and surface needs to be tailored. Three tagged synthetic polymers with different functionalities are examined: poly(acrylic acid) (PAA), poly(3-sulfopropyl methacrylate, potassium salt) (PSPMA), and a mannose-modified glycopolymer. Adsorption transients at the silica/water interface are found to be characteristic for each polymer, and kinetics are deduced from the initial rates. The chemistry of the adsorption interfaces has been varied by, first, manipulation of silica surface chemistry via the bulk pH, followed by surfaces modified by poly(L-glutamic acid) (PGA) and cellulose, giving five chemically different surfaces. Complementary atomic force microscopy (AFM) imaging has been used for additional surface characterization of adsorbed layers and functionalized interfaces to allow adsorption rates to be interpreted more fully. Adsorption rates for PSPMA and the glycopolymer are seen to be highly surface sensitive, with significantly higher rates on cellulose-modified surfaces, whereas PAA shows a much smaller rate dependence on the nature of the adsorption surface.

  7. Structural properties of the intrinsically disordered, multiple calcium ion-binding otolith matrix macromolecule-64 (OMM-64).

    Science.gov (United States)

    Poznar, Monika; Hołubowicz, Rafał; Wojtas, Magdalena; Gapiński, Jacek; Banachowicz, Ewa; Patkowski, Adam; Ożyhar, Andrzej; Dobryszycki, Piotr

    2017-11-01

    Fish otoliths are calcium carbonate biominerals that are involved in hearing and balance sensing. An organic matrix plays a crucial role in their formation. Otolith matrix macromolecule-64 (OMM-64) is a highly acidic, calcium-binding protein (CBP) found in rainbow trout otoliths. It is a component of high-molecular-weight aggregates, which influence the size, shape and polymorph of calcium carbonate in vitro. In this study, a protocol for the efficient expression and purification of OMM-64 was developed. For the first time, the complete structural characteristics of OMM-64 were described. Various biophysical methods were combined to show that OMM-64 occurs as an intrinsically disordered monomer. Under denaturing conditions (pH, temperature) OMM-64 exhibits folding propensity. It was determined that OMM-64 binds approximately 61 calcium ions with millimolar affinity. The folding-unfolding experiments showed that calcium ions induced the collapse of OMM-64. The effect of other counter ions present in trout endolymph on OMM-64 conformational changes was studied. The significance of disordered properties of OMM-64 and the possible function of this protein is discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. QM/MM hybrid calculation of biological macromolecules using a new interface program connecting QM and MM engines

    Energy Technology Data Exchange (ETDEWEB)

    Hagiwara, Yohsuke; Tateno, Masaru [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba Science City, Ibaraki 305-8571 (Japan); Ohta, Takehiro [Center for Computational Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba Science City, Ibaraki 305-8577 (Japan)], E-mail: tateno@ccs.tsukuba.ac.jp

    2009-02-11

    An interface program connecting a quantum mechanics (QM) calculation engine, GAMESS, and a molecular mechanics (MM) calculation engine, AMBER, has been developed for QM/MM hybrid calculations. A protein-DNA complex is used as a test system to investigate the following two types of QM/MM schemes. In a 'subtractive' scheme, electrostatic interactions between QM/MM regions are truncated in QM calculations; in an 'additive' scheme, long-range electrostatic interactions within a cut-off distance from QM regions are introduced into one-electron integration terms of a QM Hamiltonian. In these calculations, 338 atoms are assigned as QM atoms using Hartree-Fock (HF)/density functional theory (DFT) hybrid all-electron calculations. By comparing the results of the additive and subtractive schemes, it is found that electronic structures are perturbed significantly by the introduction of MM partial charges surrounding QM regions, suggesting that biological processes occurring in functional sites are modulated by the surrounding structures. This also indicates that the effects of long-range electrostatic interactions involved in the QM Hamiltonian are crucial for accurate descriptions of electronic structures of biological macromolecules.

  9. Magnetization transfer from macromolecules to water protons in murine dental tissues as revealed by 500 MHz 1H-NMR

    International Nuclear Information System (INIS)

    Nakamura, Koji; Era, Seiichi; Nagai, Naoki; Sogami, Masaru; Takasaki, Akihiko; Kato, Kazuo.

    1997-01-01

    Although much is known about magnetization transfer phenomena in biological soft tissues, little is known about those in hard tissues. Using a 500 MHz 1 H-NMR spectrometer, we studied the spin-lattice relaxation time (T 1 (H 2 O)) and the intermolecular cross-relaxation times (T IS (H 2 O)) from irradiated macromolecular protons to observed water protons in murine lower incisors (hard tissue) and compared with those in murine lens tissue (soft tissue). Mean values for the water content (%) of murine lower incisors and lens tissue were 16.02±2.39 (n=14) and 67.20±4.60 (n=15), respectively. These findings were consistent with the large different in water content between soft tissues and hard tissues. T IS (H 2 O) values obtained by f 2 -irradiation at 7.13 or -4.00 ppm showed no significant difference between lower incisors and lens tissue. Plots of 1/T IS (H 2 O) values vs. tissue dry weight (W(%)) for lower incisor tissue approximated a straight line with slope approximately equal for that obtained for lens tissue. These results suggest that the state of water in hard tissue may be similar to that in soft tissues, in spite of the significant difference in water content. Thus, saturation transfer NMR techniques such as measurement of T IS (H 2 O) values may be applicable to the study of water-macromolecule interactions in both biological soft and hard tissues. (author)

  10. A new highly adaptable design of shear-flow device for orientation of macromolecules for Linear Dichroism (LD) measurement

    KAUST Repository

    Lundahl, P. Johan; Kitts, Catherine C.; Nordé n, Bengt

    2011-01-01

    This article presents a new design of flow-orientation device for the study of bio-macromolecules, including DNA and protein complexes, as well as aggregates such as amyloid fibrils and liposome membranes, using Linear Dichroism (LD) spectroscopy. The design provides a number of technical advantages that should make the device inexpensive to manufacture, easier to use and more reliable than existing techniques. The degree of orientation achieved is of the same order of magnitude as that of the commonly used concentric cylinders Couette flow cell, however, since the device exploits a set of flat strain-free quartz plates, a number of problems associated with refraction and birefringence of light are eliminated, increasing the sensitivity and accuracy of measurement. The device provides similar shear rates to those of the Couette cell but is superior in that the shear rate is constant across the gap. Other major advantages of the design is the possibility to change parts and vary sample volume and path length easily and at a low cost. © 2011 The Royal Society of Chemistry.

  11. Oxidative damage to biological macromolecules in Prague bus drivers and garagemen: impact of air pollution and genetic polymorphisms.

    Science.gov (United States)

    Bagryantseva, Yana; Novotna, Bozena; Rossner, Pavel; Chvatalova, Irena; Milcova, Alena; Svecova, Vlasta; Lnenickova, Zdena; Solansky, Ivo; Sram, Radim J

    2010-11-10

    DNA integrity was investigated in the lymphocytes of 50 bus drivers, 20 garagemen and 50 controls using the comet assay with excision repair enzymes. In parallel, 8-oxo-7,8-dihydro-2'-deoxyguanosine and 15-F(2t)-isoprostane levels in the urine and protein carbonyl levels in the plasma were assessed as markers of oxidative damage to DNA, lipids and proteins. Exposure to carcinogenic polycyclic aromatic hydrocarbons (cPAHs) and volatile compounds was measured by personal samplers for 48 and 24h, respectively, before the collection of biological specimens. Both exposed groups exhibited a higher levels of DNA instability and oxidative damage to biological macromolecules than the controls. The incidence of oxidized lesions in lymphocyte DNA, but not the urinary levels of 8-oxodG, correlated with exposure to benzene and triglycerides increased this damage. Oxidative damage to lipids and proteins was associated with exposure to cPAHs and the lipid peroxidation levels positively correlated with age and LDL cholesterol, and negatively with vitamin C. The carriers of at least one variant hOGG1 (Cys) allele tended to higher oxidative damage to lymphocyte DNA than those with the wild genotype, while XPD23 (Gln/Gln) homozygotes were more susceptible to the induction of DNA strand breaks. In contrast, GSTM1 null variant seemed to protect DNA integrity. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  12. Automating the application of smart materials for protein crystallization.

    Science.gov (United States)

    Khurshid, Sahir; Govada, Lata; El-Sharif, Hazim F; Reddy, Subrayal M; Chayen, Naomi E

    2015-03-01

    The fabrication and validation of the first semi-liquid nonprotein nucleating agent to be administered automatically to crystallization trials is reported. This research builds upon prior demonstration of the suitability of molecularly imprinted polymers (MIPs; known as `smart materials') for inducing protein crystal growth. Modified MIPs of altered texture suitable for high-throughput trials are demonstrated to improve crystal quality and to increase the probability of success when screening for suitable crystallization conditions. The application of these materials is simple, time-efficient and will provide a potent tool for structural biologists embarking on crystallization trials.

  13. SAXS measurements of crystallization in Me PEEK

    International Nuclear Information System (INIS)

    Barberato, C.; Kellerman, G.; Craievich, A.F.; Torriani, I.L.

    1997-01-01

    Full text. Preliminary small-angle x-ray scattering (SAXS) measurements on a variety of methyl-substituted poly(aryl ether ether ketone) (Me PEEK) samples have been performed at the D11AA-SAXS beam line of the Brazilian National Synchrotron Light Laboratory (LNLS).Me PEEK is an industrially important thermoplastic material exhibiting crystallization upon annealing at temperatures between 175 and 200 deg C. Differential Scanning Calorimetry (DSC) measurements (Handa Y.P., Roovers, J., Wang, F., Macromolecules 27(19), 551-5516 (1994)) indicate that the presence of supercritical fluids during thermal treatment can have dramatic effects on the melting behavior of Me PEEK when compared to similar data for materials annealed in air. These observations have been made for samples demonstrating no significant differences in the extent of crystallinity suggesting that it is the nature of the crystallites that is affected by the presence of additives during the thermal treatment. In this preliminary study, scattering profiles for three Me PEEK samples (as received, thermally treated in air and thermally treated with supercritical 0.85 CO 2 +C H 3 O H gas) are obtained. The data are analyzed to provide some measure of the variation in crystallite structure between the thermally treated samples. Scattering data obtained in the very small-angle region on the same samples at the High Brilliance Beamline (ID2/BM4) experiments performed by Olivier Diat and M.A. Singh, Dec. 11996) of the European Synchrotron Radiation Facility (ESRF) is combined with the Brazilian National Laboratory on Synchrotron Light (LNLS) data to provide information over 3 decades of scattering angle. This work is part of a larger study of the use of supercritical fluids to control the level and morphology of crystallization in these materials. (author)

  14. Thermochemolysis: A New Sample Preparation Approach for the Detection of Organic Components of Complex Macromolecules in Mars Rocks via Gas Chromatography Mass Spectrometry in SAM on MSL

    Science.gov (United States)

    Eugenbrode, J.; Glavin, D.; Dworkin, J.; Conrad, P.; Mahaffy, P.

    2011-01-01

    Organic chemicals, when present in extraterrestrial samples, afford precious insight into past and modern conditions elsewhere in the Solar System . No single technology identifies all molecular components because naturally occurring molecules have different chemistries (e.g., polar vs. non-polar, low to high molecular weight) and interface with the ambient sample chemistry in a variety of modes (i.e., organics may be bonded, absorbed or trapped by minerals, liquids, gases, or other organics). More than 90% of organic matter in most natural samples on Earth and in meteorites is composed of complex macromolecules (e.g. biopolymers, complex biomolecules, humic substances, kerogen) because the processes that tend to break down organic molecules also tend towards complexation of the more recalcitrant components. Thus, methodologies that tap the molecular information contained within macromolecules may be critical to detecting extraterrestrial organic matter and assessing the sources and processes influencing its nature.

  15. Rate Measurements of the Hydrolysis of Complex Organic Macromolecules in Cold Aqueous Solutions: Implications for Prebiotic Chemistry on the Early Earth and Titan

    Science.gov (United States)

    Neish, C. D.; Somogyi, Á.; Imanaka, H .; Lunine, J. I.; Smith, M. A.

    2008-04-01

    Organic macromolecules (``complex tholins'') were synthesized from a 0.95 N2 / 0.05 CH4 atmosphere in a high-voltage AC flow discharge reactor. When placed in liquid water, specific water soluble compounds in the macromolecules demonstrated Arrhenius type first order kinetics between 273 and 313 K and produced oxygenated organic species with activation energies in the range of ~60 +/- 10 kJ mol-1. These reactions displayed half lives between 0.3 and 17 days at 273 K. Oxygen incorporation into such materials-a necessary step toward the formation of biological molecules-is therefore fast compared to processes that occur on geologic timescales, which include the freezing of impact melt pools and possible cryovolcanic sites on Saturn's organic-rich moon Titan.

  16. Photonic crystal pioneer

    Science.gov (United States)

    Anscombe, Nadya

    2011-08-01

    Over the past ten years, Crystal Fiber, now part of NKT Photonics, has been busy commercializing photonic crystal fibre. Nadya Anscombe finds out about the evolution of the technology and its applications.

  17. Crystallization Pathways in Biomineralization

    Science.gov (United States)

    Weiner, Steve; Addadi, Lia

    2011-08-01

    A crystallization pathway describes the movement of ions from their source to the final product. Cells are intimately involved in biological crystallization pathways. In many pathways the cells utilize a unique strategy: They temporarily concentrate ions in intracellular membrane-bound vesicles in the form of a highly disordered solid phase. This phase is then transported to the final mineralization site, where it is destabilized and crystallizes. We present four case studies, each of which demonstrates specific aspects of biological crystallization pathways: seawater uptake by foraminifera, calcite spicule formation by sea urchin larvae, goethite formation in the teeth of limpets, and guanine crystal formation in fish skin and spider cuticles. Three representative crystallization pathways are described, and aspects of the different stages of crystallization are discussed. An in-depth understanding of these complex processes can lead to new ideas for synthetic crystallization processes of interest to materials science.

  18. Photonic Crystal Nanocavity Arrays

    National Research Council Canada - National Science Library

    Altug, Hatice; Vuckovic, Jelena

    2006-01-01

    We recently proposed two-dimensional coupled photonic crystal nanocavity arrays as a route to achieve a slow-group velocity of light in all crystal directions, thereby enabling numerous applications...

  19. Growth of dopamine crystals

    Energy Technology Data Exchange (ETDEWEB)

    Patil, Vidya, E-mail: vidya.patil@ruparel.edu; Patki, Mugdha, E-mail: mugdha.patki@ruparel.edu [D. G. Ruparel College, Senapati Bapat Marg, Mahim, Mumbai – 400 016 (India)

    2016-05-06

    Many nonlinear optical (NLO) crystals have been identified as potential candidates in optical and electro-optical devices. Use of NLO organic crystals is expected in photonic applications. Hence organic nonlinear optical materials have been intensely investigated due to their potentially high nonlinearities, and rapid response in electro-optic effect compared to inorganic NLO materials. There are many methods to grow organic crystals such as vapor growth method, melt growth method and solution growth method. Out of these methods, solution growth method is useful in providing constraint free crystal. Single crystals of Dopamine have been grown by evaporating the solvents from aqueous solution. Crystals obtained were of the size of orders of mm. The crystal structure of dopamine was determined using XRD technique. Images of crystals were obtained using FEG SEM Quanta Series under high vacuum and low KV.

  20. Apparatus for mounting crystal

    Science.gov (United States)

    Longeway, Paul A.

    1985-01-01

    A thickness monitor useful in deposition or etching reactor systems comprising a crystal-controlled oscillator in which the crystal is deposited or etched to change the frequency of the oscillator. The crystal rests within a thermally conductive metallic housing and arranged to be temperature controlled. Electrode contacts are made to the surface primarily by gravity force such that the crystal is substantially free of stress otherwise induced by high temperature.

  1. ALICE photon spectrometer crystals

    CERN Multimedia

    Maximilien Brice

    2006-01-01

    Members of the mechanical assembly team insert the last few crystals into the first module of ALICE's photon spectrometer. These crystals are made from lead-tungstate, a crystal as clear as glass but with nearly four times the density. When a high-energy particle passes through one of these crystals it will scintillate, emitting a flash of light allowing the energy of photons, electrons and positrons to be measured.

  2. Role of endothelial permeability hotspots and endothelial mitosis in determining age-related patterns of macromolecule uptake by the rabbit aortic wall near branch points.

    Science.gov (United States)

    Chooi, K Yean; Comerford, Andrew; Cremers, Stephanie J; Weinberg, Peter D

    2016-07-01

    Transport of macromolecules between plasma and the arterial wall plays a key role in atherogenesis. Scattered hotspots of elevated endothelial permeability to macromolecules occur in the aorta; a fraction of them are associated with dividing cells. Hotspots occur particularly frequently downstream of branch points, where lesions develop in young rabbits and children. However, the pattern of lesions varies with age, and can be explained by similar variation in the pattern of macromolecule uptake. We investigated whether patterns of hotspots and mitosis also change with age. Evans' Blue dye-labeled albumin was injected intravenously into immature or mature rabbits and its subsequent distribution in the aortic wall around intercostal branch ostia examined by confocal microscopy and automated image analysis. Mitosis was detected by immunofluorescence after adding 5-bromo-2-deoxiuridine to drinking water. Hotspots were most frequent downstream of branches in immature rabbits, but a novel distribution was observed in mature rabbits. Neither pattern was explained by mitosis. Hotspot uptake correlated spatially with the much greater non-hotspot uptake (p hotspots were considered. The pattern of hotspots changes with age. The data are consistent with there being a continuum of local permeabilities rather than two distinct mechanisms. The distribution of the dye, which binds to elastin and collagen, was similar to that of non-binding tracers and to lesions apart from a paucity at the lateral margins of branches that can be explained by lower levels of fibrous proteins in those regions. Copyright © 2016. Published by Elsevier Ireland Ltd.

  3. Optical microcavities based on surface modes in two-dimensional photonic crystals and silicon-on-insulator photonic crystals

    DEFF Research Database (Denmark)

    Xiao, Sanshui; Qiu, M.

    2007-01-01

    Surface-mode optical microcavities based on two-dimensional photonic crystals and silicon-on-insulator photonic crystals are studied. We demonstrate that a high-quality-factor microcavity can be easily realized in these structures. With an increasing of the cavity length, the quality factor is gr...... is gradually enhanced and the resonant frequency converges to that of the corresponding surface mode in the photonic crystals. These structures have potential applications such as sensing.......Surface-mode optical microcavities based on two-dimensional photonic crystals and silicon-on-insulator photonic crystals are studied. We demonstrate that a high-quality-factor microcavity can be easily realized in these structures. With an increasing of the cavity length, the quality factor...

  4. Crystal Growth Technology

    Science.gov (United States)

    Scheel, Hans J.; Fukuda, Tsuguo

    2004-06-01

    This volume deals with the technologies of crystal fabrication, of crystal machining, and of epilayer production and is the first book on industrial and scientific aspects of crystal and layer production. The major industrial crystals are treated: Si, GaAs, GaP, InP, CdTe, sapphire, oxide and halide scintillator crystals, crystals for optical, piezoelectric and microwave applications and more. Contains 29 contributions from leading crystal technologists covering the following topics: General aspects of crystal growth technology Silicon Compound semiconductors Oxides and halides Crystal machining Epitaxy and layer deposition Scientific and technological problems of production and machining of industrial crystals are discussed by top experts, most of them from the major growth industries and crystal growth centers. In addition, it will be useful for the users of crystals, for teachers and graduate students in materials sciences, in electronic and other functional materials, chemical and metallurgical engineering, micro-and optoelectronics including nanotechnology, mechanical engineering and precision-machining, microtechnology, and in solid-state sciences.

  5. Food crystallization and eggs.

    Science.gov (United States)

    Egg products can be utilized to control crystallization in a diverse realm of food products. Albumen and egg yolk can aid in the control of sugar crystal formation in candies. Egg yolk can enhance the textural properties and aid in the control of large ice crystal formation in frozen desserts. In...

  6. An Integrated Approach to III-Nitride Crystal Growth and Wafering

    National Research Council Canada - National Science Library

    Sitar, Z

    2001-01-01

    Centimeter size, transparent AlN crystals were grown at NCSU. TEM and XRT examination performed at ASU and SUNYSB revealed that the crystals are of highest quality and do not contain any visible extended defects...

  7. The Growth of Protein Crystals Using McDUCK

    Science.gov (United States)

    Ewing, Felicia; Wilson, Lori; Nadarajah, Arunan; Pusey, Marc

    1998-01-01

    grown we are currently proposing McDUCK for the growth of macromolecule crystals for use in neutron diffraction studies.

  8. Studies on growth, crystal structure and characterization of novel organic nicotinium trifluoroacetate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Dhanaraj, P.V. [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam 603 110 (India); Rajesh, N.P., E-mail: rajeshnp@hotmail.com [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam 603 110 (India); Sundar, J. Kalyana; Natarajan, S. [Department of Physics, Madurai Kamaraj University, Madurai 625 021 (India); Vinitha, G. [Department of Physics, Crescent Engineering College, Chennai 600 048 (India)

    2011-09-15

    Highlights: {yields} Good quality crystals of nicotinium trifluoroacetate in monoclinic system were grown for first time. {yields} Nicotinium trifluoroacetate crystal exhibits third order nonlinear optical properties. {yields} The optical spectrum of nicotinium trifluoroacetate crystal reveals the wide transmission in the entire range with cutoff wavelength at 286 nm. {yields} Nicotinium trifluoroacetate is a low dielectric constant material. - Abstract: An organic material, nicotinium trifluoroacetate (NTF) was synthesized and single crystals in monoclinic system were grown from aqueous solution for the first time. Its solubility and metastable zone width were estimated. The crystal structure of NTF was analyzed to reveal the molecular arrangements and the formation of hydrogen bonds in the crystal. High-resolution X-ray diffraction rocking curve measurements were performed to analyze the structural perfection of the grown crystals. Functional groups in NTF were identified by Fourier transform infrared spectral analysis. Thermal behaviour and stability of NTF were studied by thermogravimetric and differential thermal analysis and differential scanning calorimetry. Mechanical and dielectric properties of NTF crystals were analyzed. Optical studies reveal that NTF crystals are transparent in the wavelength range 286-1100 nm. The third order nonlinear optical parameters of NTF were derived by the Z-scan technique.

  9. One-pot synthesis of star-shaped macromolecules containing polyglycidol and poly(ethylene oxide) arms.

    Science.gov (United States)

    Lapienis, Grzegorz; Penczek, Stanislaw

    2005-01-01

    Synthesis of fully hydrophilic star-shaped macromolecules with different kinds of arms (A(x)B(y)C(z)) based on polyglycidol (PGL, A(x)) and poly(ethylene oxide) (PEO, C(z)) arms and diepoxy compounds (diglycidyl ethers of ethylene glycol (DGEG) or neopentyl glycol (DGNG) in the core, B(y)) forming the core is described. Precursors of arms were prepared by polymerization of glycidol with protected -OH groups. The first-generation stars were formed in the series of consecutive-parallel reactions of arms A(x) with diepoxy compounds (B). These first-generation stars (A(x)B(y)), having approximately O-, Mt+ groups on the cores, were used as multianionic initiators for the second generation of arms (C(z)) built by polymerization of ethylene oxide. The products with M(n) up to 10(5) and having up to approximately 40 arms were obtained. The number of arms (f) was determined by direct measurements of M(n) of the first-generation stars (M(n) of arms A(x) is known), compared with f calculated from the branching index g, determined from R(g) measured with size-exclusion chromatography (SEC) triple detection with TriSEC software. The progress of the star formation was monitored by 1H NMR and SEC. These novel water-soluble stars, having a large number of hydroxyl groups, both at the ends of PEO arms as well as within the PGL arms, can be functionalized and further used for attaching compounds of interest. This approach opens, therefore, a new way of "multiPEGylation".

  10. S-protected thiolated chitosan for oral delivery of hydrophilic macromolecules: evaluation of permeation enhancing and efflux pump inhibitory properties.

    Science.gov (United States)

    Dünnhaupt, Sarah; Barthelmes, Jan; Rahmat, Deni; Leithner, Katharina; Thurner, Clemens C; Friedl, Heike; Bernkop-Schnürch, Andreas

    2012-05-07

    The objective of this study was the investigation of permeation enhancing and P-glycoprotein (P-gp) inhibition effects of a novel thiolated chitosan, the so-named S-protected thiolated chitosan. Mediated by a carbodiimide, increasing amounts of thioglycolic acid (TGA) were covalently bound to chitosan (CS) in the first step of modification. In the second step, these thiol groups of thiolated chitosan were protected by disulfide bond formation with the thiolated aromatic residue 6-mercaptonicotinamide (6-MNA). Mucoadhesive properties of all conjugates were evaluated in vitro on porcine intestinal mucosa based on tensile strength investigations. Permeation enhancing effects were evaluated ex vivo using rat intestinal mucosa and in vitro via Caco-2 cells using the hydrophilic macromolecule FD(4) as the model drug. Caco-2 cells were further used to show P-gp inhibition effects by using Rho-123 as P-gp substrate. Apparent permeability coefficients (P(app)) were calculated and compared to values obtained from each buffer control. Three different thiolated chitosans were generated in the first step of modification, which displayed increasing amounts of covalently attached free thiol groups on the polymer backbone. In the second modification step, more than 50% of these free thiol groups were covalently linked with 6-MNA. Within 3 h of permeation studies on excised rat intestine, P(app) values of all S-protected chitosans were at least 1.3-fold higher compared to those of corresponding thiomers and more than twice as high as that of unmodified chitosan. Additional permeation studies on Caco-2 cells confirmed these results. Because of the chemical modification and higher amount of reactive thiol groups, all S-protected thiolated chitosans exhibit at least 1.4-fold pronounced P-gp inhibition effects in contrast to their corresponding thiomers. These features approve S-protected thiolated chitosan as a promising excipient for various drug delivery systems providing improved

  11. Physiochemical and spectroscopic behavior of actinides and lanthanides in solution, their sorption on minerals and their compounds formed with macromolecules

    International Nuclear Information System (INIS)

    Jimenez R, M.

    2010-01-01

    From the chemical view point, the light actinides has been those most studied; particularly the uranium, because is the primordial component of the nuclear reactors. The chemical behavior of these elements is not completely defined, since they can behave as transition metals or metals of internal transition, as they are the lanthanides. The actinides are radioactive; between them they are emitters of radiation alpha, highly toxic, of live half long and some very long, and artificial elements. For all this, to know them sometimes is preferable to use their chemical similarity with the lanthanides and to study these. In particular, the migration of emitters of radiation alpha to the environment has been studied taking as model the uranium. It is necessary to mention that actinides and lanthanides elements are in the radioactive wastes of the nuclear reactors. In the Chemistry Department of the Instituto Nacional de Investigaciones Nucleares (ININ) the researches about the actinides and lanthanides began in 1983 and, between that year and 1995 several works were published in this field. In 1993 the topic was proposed as a Department project and from then around of 13 institutional projects and managerial activity have been developed, besides 4 projects approved by the National Council of Science and Technology. The objective of the projects already developed and of the current they have been contributing knowledge for the understanding of the chemical behavior of the lanthanides and actinides, as much in solution as in the solid state, their behavior in the environment and the chemistry of their complexes with recurrent and lineal macromolecules. (Author)

  12. Zinc ions regulate opening of tight junction favouring efflux of macromolecules via the GSK3β/snail-mediated pathway.

    Science.gov (United States)

    Xiao, Ruyue; Yuan, Lan; He, Weijiang; Yang, Xiaoda

    2018-01-24

    Zinc is an essential trace element presenting in particularly high concentration in the brain. In some regions, e.g. lateral amygdala, subiculum and hippocampus, rapidly-exchangeable zinc may transiently reach even up to 600 μM. To explore the possible roles of high-concentration Zn 2+ in regulating the blood-brain barrier (BBB), we investigated the effects of Zn 2+ on the functions and structures of the tight junction (TJ) with an in vitro model of a Madin-Darby canine kidney (MDCK) cell monolayer. The experimental results indicated that high concentrations (>200 μM) of Zn 2+ can affect the TJ integrity in a polarized manner. Basolateral addition of Zn 2+ led to reversible TJ opening with pore paths of r ∼ 2 nm or more depending on Zn 2+ concentration. The efflux/influx ratios of different sized probes were found to be ∼4.6 for FD4 (M W 4000) and ∼1.8 for Eu-DTPA (M W 560), suggesting that the Zn 2+ -induced paracelluar channels favour efflux especially for macromolecules. Further mechanistic studies revealed that the elevated intracellular Zn 2+ taken from the basolateral side can increase phosphorylation of glycogen synthase kinase (GSK) 3β, primarily due to the inhibition of calcineurin (CaN), thus resulting in the elevation of the snail transcriptional repressors. Subsequently, Zn 2+ can cause the down-regulation of claudin-1, breakage of occludin and ZO-1 rings, and collapse of basolateral F-actin structures. These overall factors result in the formation of a trumpet-like paracellular channel, which allows asymmetric solute permeation. The ERK1/2 and JNK1/2 pathways may also be involved in the Zn 2+ -induced TJ opening process, while the activation of matrix metalloproteinase was not observed. Our results may suggest a potential role of zinc in regulation of BBB permeability associated with brain clearance of metabolites through the glymphatic system.

  13. Physico-mechanical and dissolution behaviours of ibuprofen crystals crystallized in the presence of various additives

    Directory of Open Access Journals (Sweden)

    A Nokhodchi

    2010-06-01

    Full Text Available "n  "n Background and the purpose of the study: The success of any direct-tableting procedure is strongly affected by the quality of the crystals used in the process. Ibuprofen is a poorly compactible drug with a high tendency for capping. In order to use ibuprofen in direct compression formulations, physico-mechanical properties of ibuprofen should be improved considerably. The aim of the present investigation was to employ crystallization techniques in order to improve the physico-mechanical properties of ibuprofen for direct compression. "nMethods:The experimental methods involved the preparation of ibuprofen crystals by solvent change technique. Ibuprofen was dissolved in ethanol and crystallized out with water in the absence or presence of various hydrophilic additives (PEG 6000, 8000, Brij 98P and polyvinyl alcohol 22000, PVA 22000 with different concentrations. The physico-mechanical properties of the ibuprofen crystals were studied in terms of flow, density, tensile strength and dissolution behaviour. Morphology of ibuprofen crystals was studied by scanning electron microscopic (SEM. Solid state of the recrystallized particles was also investigated using differential scanning calorimeter (DSC and FT-IR. "nResults:Ibuprofen samples crystallized in the presence of PEG 6000 and 8000 and PVA showed remarkable increase in the tensile strengths of the directly compressed tablets, while some other additives, i.e. Brij 98P did not produce improved ibuprofen crystals. Ibuprofen powders made from particles obtained in the presence of PVA and Brij 98P showed similar dissolution profiles to the commercial ibuprofen particles. DSC and FT-IR results ruled out any significant interaction between ibuprofen and additives except for the samples crystallized in the presence of PEG 8000. Conclusion:The crystal habit of ibuprofen can be altered successfully by the crystallization technique which was developed in this study. The crystals developed in the

  14. Multi-crystal native SAD analysis at 6 keV.

    Science.gov (United States)

    Liu, Qun; Guo, Youzhong; Chang, Yanqi; Cai, Zheng; Assur, Zahra; Mancia, Filippo; Greene, Mark I; Hendrickson, Wayne A

    2014-10-01

    Anomalous diffraction signals from typical native macromolecules are very weak, frustrating their use in de novo structure determination. Here, native SAD procedures are described to enhance signal to noise in anomalous diffraction by using multiple crystals in combination with synchrotron X-rays at 6 keV. Increased anomalous signals were obtained at 6 keV compared with 7 keV X-ray energy, which was used for previous native SAD analyses. A feasibility test of multi-crystal-based native SAD phasing was performed at 3.2 Å resolution for a known tyrosine protein kinase domain, and real-life applications were made to two novel membrane proteins at about 3.0 Å resolution. The three applications collectively serve to validate the robust feasibility of native SAD phasing at lower energy.

  15. Identification of a macromolecular crystal growth inhibitor in human urine as osteopontin

    DEFF Research Database (Denmark)

    Sørensen, Steen; Justesen, S J; Johnsen, A H

    1995-01-01

    , an unidentified protein rich in uronic acid, and uropontin have all been described as possessing such activity. We have recently isolated an unknown inhibitor of calcium oxalate crystal growth that co-eluted with trypsin inhibitor in several separation steps, which suggested its identity. The aim of the present......Macromolecules occurring in human urine inhibit the growth and/or aggregation of calcium oxalate crystals and may prevent the formation of kidney stones. Attention has focused particularly on proteins, as these seem to be most responsible for the inhibitory activity; three proteins, nephrocalcin...... study was to outline a simple procedure for isolating and identifying this inhibitor. Purification was done as follows: precipitation of the major proteins (albumin and uromucoid) with trichloroacetic acid, followed by anion exchange chromatography, hydroxyapatite chromatography, anion exchange...

  16. Implication of Crystal Water Molecules in Inhibitor Binding at ALR2 Active Site

    Directory of Open Access Journals (Sweden)

    Hymavati

    2012-01-01

    Full Text Available Water molecules play a crucial role in mediating the interaction between a ligand and a macromolecule. The solvent environment around such biomolecule controls their structure and plays important role in protein-ligand interactions. An understanding of the nature and role of these water molecules in the active site of a protein could greatly increase the efficiency of rational drug design approaches. We have performed the comparative crystal structure analysis of aldose reductase to understand the role of crystal water in protein-ligand interaction. Molecular dynamics simulation has shown the versatile nature of water molecules in bridge H bonding during interaction. Occupancy and life time of water molecules depend on the type of cocrystallized ligand present in the structure. The information may be useful in rational approach to customize the ligand, and thereby longer occupancy and life time for bridge H-bonding.

  17. Protein Crystal Growth

    Science.gov (United States)

    2003-01-01

    In order to rapidly and efficiently grow crystals, tools were needed to automatically identify and analyze the growing process of protein crystals. To meet this need, Diversified Scientific, Inc. (DSI), with the support of a Small Business Innovation Research (SBIR) contract from NASA s Marshall Space Flight Center, developed CrystalScore(trademark), the first automated image acquisition, analysis, and archiving system designed specifically for the macromolecular crystal growing community. It offers automated hardware control, image and data archiving, image processing, a searchable database, and surface plotting of experimental data. CrystalScore is currently being used by numerous pharmaceutical companies and academic and nonprofit research centers. DSI, located in Birmingham, Alabama, was awarded the patent Method for acquiring, storing, and analyzing crystal images on March 4, 2003. Another DSI product made possible by Marshall SBIR funding is VaporPro(trademark), a unique, comprehensive system that allows for the automated control of vapor diffusion for crystallization experiments.

  18. Photonic crystal light source

    Science.gov (United States)

    Fleming, James G [Albuquerque, NM; Lin, Shawn-Yu [Albuquerque, NM; Bur, James A [Corrales, NM

    2004-07-27

    A light source is provided by a photonic crystal having an enhanced photonic density-of-states over a band of frequencies and wherein at least one of the dielectric materials of the photonic crystal has a complex dielectric constant, thereby producing enhanced light emission at the band of frequencies when the photonic crystal is heated. The dielectric material can be a metal, such as tungsten. The spectral properties of the light source can be easily tuned by modification of the photonic crystal structure and materials. The photonic crystal light source can be heated electrically or other heating means. The light source can further include additional photonic crystals that exhibit enhanced light emission at a different band of frequencies to provide for color mixing. The photonic crystal light source may have applications in optical telecommunications, information displays, energy conversion, sensors, and other optical applications.

  19. Beginner’s guide to flux crystal growth

    CERN Document Server

    Tachibana, Makoto

    2017-01-01

    This book introduces the principles and techniques of crystal growth by the flux method, which is arguably the most useful way to obtain millimeter- to centimeter-sized single crystals for physical research. As it is possible to find an appropriate solvent (“flux”) for nearly all inorganic materials, the flux method can be applied to the growth of many crystals ranging from transition metal oxides to intermetallic compounds. Both important principles and experimental procedures are described in a clear and accessible manner. Practical advice on various aspects of the experiment, which is not readily available in the literature, will assist the beginning graduate students in setting up the lab and conducting successful crystal growth. The mechanisms of crystal growth at an elementary level are also provided to better understand the techniques and to help in assessing the quality of the crystals. The book also contains many photographs of beautiful crystals with important physical properties of current inte...

  20. Automating the application of smart materials for protein crystallization

    International Nuclear Information System (INIS)

    Khurshid, Sahir; Govada, Lata; EL-Sharif, Hazim F.; Reddy, Subrayal M.; Chayen, Naomi E.

    2015-01-01

    The first semi-liquid, non-protein nucleating agent for automated protein crystallization trials is described. This ‘smart material’ is demonstrated to induce crystal growth and will provide a simple, cost-effective tool for scientists in academia and industry. The fabrication and validation of the first semi-liquid nonprotein nucleating agent to be administered automatically to crystallization trials is reported. This research builds upon prior demonstration of the suitability of molecularly imprinted polymers (MIPs; known as ‘smart materials’) for inducing protein crystal growth. Modified MIPs of altered texture suitable for high-throughput trials are demonstrated to improve crystal quality and to increase the probability of success when screening for suitable crystallization conditions. The application of these materials is simple, time-efficient and will provide a potent tool for structural biologists embarking on crystallization trials

  1. Ultrastructure, macromolecules, and evolution

    CERN Document Server

    Dillon, Lawrence S

    1981-01-01

    Thus far in the history of biology, two, and only two, fundamental principles have come to light that pervade and unify the entire science-the cell theory and the concept of evolution. While it is true that recently opened fields of inves­ tigation have given rise to several generalizations of wide impact, such as the universality of DNA and the energetic dynamics of ecology, closer inspection reveals them to be part and parcel of either of the first two mentioned. Because in the final analysis energy can act upon an organism solely at the cellular level, its effects may be perceived basically to represent one facet of cell me­ tabolism. Similarly, because the DNA theory centers upon the means by which cells build proteins and reproduce themselves, it too proves to be only one more, even though an exciting, aspect of the cell theory. In fact, if the matter is given closer scrutiny, evolution itself can be viewed as being a fundamental portion of the cell concept, for its effects arise only as a consequence ...

  2. CH3NH3PbCl3 Single Crystals: Inverse Temperature Crystallization and Visible-Blind UV-Photodetector

    KAUST Repository

    Maculan, Giacomo

    2015-09-02

    Single crystals of hybrid perovskites have shown remarkably improved physical properties compared to their polycrystalline film counterparts, underscoring their importance in the further development of advanced semiconductor devices. Here we present a new method of sizeable CH3NH3PbCl3 single crystal growth based on retrograde solubility behavior of hybrid perovskites. We show, for the first time, the energy band structure, charge-carrier recombination and transport properties of single crystal CH3NH3PbCl3. The chloride-based perovskite crystals exhibit trap-state density, charge carriers concentration, mobility and diffusion length comparable with the best quality crystals of methylammonium lead iodide or bromide perovskites reported so far. The high quality of the crystal along with its suitable optical bandgap enabled us to design and build an efficient visible-blind UV-photodetector, demonstrating the potential of this material to be employed in optoelectronic applications.

  3. Macromolecular Crystal Growth by Means of Microfluidics

    Science.gov (United States)

    vanderWoerd, Mark; Ferree, Darren; Spearing, Scott; Monaco, Lisa; Molho, Josh; Spaid, Michael; Brasseur, Mike; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    We have performed a feasibility study in which we show that chip-based, microfluidic (LabChip(TM)) technology is suitable for protein crystal growth. This technology allows for accurate and reliable dispensing and mixing of very small volumes while minimizing bubble formation in the crystallization mixture. The amount of (protein) solution remaining after completion of an experiment is minimal, which makes this technique efficient and attractive for use with proteins, which are difficult or expensive to obtain. The nature of LabChip(TM) technology renders it highly amenable to automation. Protein crystals obtained in our initial feasibility studies were of excellent quality as determined by X-ray diffraction. Subsequent to the feasibility study, we designed and produced the first LabChip(TM) device specifically for protein crystallization in batch mode. It can reliably dispense and mix from a range of solution constituents into two independent growth wells. We are currently testing this design to prove its efficacy for protein crystallization optimization experiments. In the near future we will expand our design to incorporate up to 10 growth wells per LabChip(TM) device. Upon completion, additional crystallization techniques such as vapor diffusion and liquid-liquid diffusion will be accommodated. Macromolecular crystallization using microfluidic technology is envisioned as a fully automated system, which will use the 'tele-science' concept of remote operation and will be developed into a research facility for the International Space Station as well as on the ground.

  4. Design of Double PG Crystal Neutron Diffractometer

    International Nuclear Information System (INIS)

    Adib, M.; Habib, N.; El-Mesiry, M.S.; Fathallah, M.

    2011-01-01

    The design of a diffractometer containing two pyrolytic graphite (PG) crystals to select monochromatic neutrons in the range of wavelengths longer than 0.26 nm is given. The first crystal is high oriented pyrolytic graphite (HOPG) set at glancing angle to reflect monochromatic neutrons with a selected wavelength. The second is a low quality PG crystal filter, set at take-off-angle such that, it transmits the selected monochromatic neutrons and rejects the higher order contaminations accompanying the first order reflection. It was shown that, 2 mm thick of PG crystal having 0.30 FWHM on mosaic spread are the optimum parameters of monochromator PG crystal. While the optimum thickness and mosaic spread of the PG crystal filter were selected to have low contamination factor of higher order reflections. The optimum parameters of the PG filter crystal were calculated using the computer package Graphite recently developed in our laboratory. Calculation shows that, 3 cm thick PG filter (20 on mosaic spread) is sufficient to almost eliminate the higher order contaminations accompanying the main monochromatic neutrons with

  5. Matrix metalloproteinase-20 mediates dental enamel biomineralization by preventing protein occlusion inside apatite crystals.

    Science.gov (United States)

    Prajapati, Saumya; Tao, Jinhui; Ruan, Qichao; De Yoreo, James J; Moradian-Oldak, Janet

    2016-01-01

    Reconstruction of enamel-like materials is a central topic of research in dentistry and material sciences. The importance of precise proteolytic mechanisms in amelogenesis to form a hard tissue with more than 95% mineral content has already been reported. A mutation in the Matrix Metalloproteinase-20 (MMP-20) gene results in hypomineralized enamel that is thin, disorganized and breaks from the underlying dentin. We hypothesized that the absence of MMP-20 during amelogenesis results in the occlusion of amelogenin in the enamel hydroxyapatite crystals. We used spectroscopy and electron microscopy techniques to qualitatively and quantitatively analyze occluded proteins within the isolated enamel crystals from MMP-20 null and Wild type (WT) mice. Our results showed that the isolated enamel crystals of MMP-20 null mice had more organic macromolecules occluded inside them than enamel crystals from the WT. The crystal lattice arrangements of MMP-20 null enamel crystals analyzed by High Resolution Transmission Electron Microscopy (HRTEM) were found to be significantly different from those of the WT. Raman studies indicated that the crystallinity of the MMP-20 null enamel crystals was lower than that of the WT. In conclusion, we present a novel functional mechanism of MMP-20, specifically prevention of unwanted organic material entrapped in the forming enamel crystals, which occurs as the result of precise amelogenin cleavage. MMP-20 action guides the growth morphology of the forming hydroxyapatite crystals and enhances their crystallinity. Elucidating such molecular mechanisms can be applied in the design of novel biomaterials for future clinical applications in dental restoration or repair. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Crystallization of protein–ligand complexes

    International Nuclear Information System (INIS)

    Hassell, Anne M.; An, Gang; Bledsoe, Randy K.; Bynum, Jane M.; Carter, H. Luke III; Deng, Su-Jun J.; Gampe, Robert T.; Grisard, Tamara E.; Madauss, Kevin P.; Nolte, Robert T.; Rocque, Warren J.; Wang, Liping; Weaver, Kurt L.; Williams, Shawn P.; Wisely, G. Bruce; Xu, Robert; Shewchuk, Lisa M.

    2007-01-01

    Methods presented for growing protein–ligand complexes fall into the categories of co-expression of the protein with the ligands of interest, use of the ligands during protein purification, cocrystallization and soaking the ligands into existing crystals. Obtaining diffraction-quality crystals has long been a bottleneck in solving the three-dimensional structures of proteins. Often proteins may be stabilized when they are complexed with a substrate, nucleic acid, cofactor or small molecule. These ligands, on the other hand, have the potential to induce significant conformational changes to the protein and ab initio screening may be required to find a new crystal form. This paper presents an overview of strategies in the following areas for obtaining crystals of protein–ligand complexes: (i) co-expression of the protein with the ligands of interest, (ii) use of the ligands during protein purification, (iii) cocrystallization and (iv) soaks

  7. Liquid nitrogen dewar for protein crystal growth

    Science.gov (United States)

    2001-01-01

    Gaseous Nitrogen Dewar apparatus developed by Dr. Alex McPherson of the University of California, Irvine for use aboard Mir and the International Space Station allows large quantities of protein samples to be crystallized in orbit. The specimens are contained either in plastic tubing (heat-sealed at each end). Biological samples are prepared with a precipitating agent in either a batch or liquid-liquid diffusion configuration. The samples are then flash-frozen in liquid nitrogen before crystallization can start. On orbit, the Dewar is placed in a quiet area of the station and the nitrogen slowly boils off (it is taken up by the environmental control system), allowing the proteins to thaw to begin crystallization. The Dewar is returned to Earth after one to four months on orbit, depending on Shuttle flight opportunities. The tubes then are analyzed for crystal presence and quality

  8. Achievement report for fiscal 1997. Technological development for practical application of a solar energy power generation system /development of technology to manufacture solar cells/development of technology to manufacture thin film solar cells (development of technology to manufacture materials and substrates (development of technology to manufacture silicon crystal based high-quality materials and substrates)); 1997 nendo taiyoko hatsuden system jitsuyoka gijutsu kaihatsu seika hokokusho. Taiyo denchi seizo gijutsu kaihatsu, usumaku taiyo denchi seizo gijutsu kaihatsu, zairyo kiban seizo gijutsu kaihatsu (silicon kesshokei kohinshitsu zairyo kiban no seizo gujutsu kaihatsu)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    It is intended to develop thin film solar cells capable of mass production with high photo-stability and at low cost. Thus, the objective of the present research is to analyze the growth process of micro crystal silicon based thin films, the crystal being a high quality silicon crystal based material, and develop technology to manufacture high-quality micro crystal silicon thin films based on the findings therefrom. It was found that, when silicon source is available in cathode, pure hydrogen plasma forms micro crystal silicon films by using the plasma as a result of the chemical transportation effect from the silicon source. It was revealed that the crystal formation due to hydrogen plasma exposure is performed substantially by the crystals forming the films due to the chemical transportation effect, rather than crystallization in the vicinity of the surface. The crystal formation under this experiment was concluded that the formation takes place during film growth accompanied by diffusion of film forming precursors on the surface on which the film grows. According to the result obtained so far, the most important issue in the future is particularly the control of crystal growing azimuth by reducing the initially formed amorphous layer by controlling the stress in the initial phase for film formation, and by controlling the film forming precursors. (NEDO)

  9. Lab-on-a-Chip Based Protein Crystallization

    Science.gov (United States)

    vanderWoerd, Mark J.; Brasseur, Michael M.; Spearing, Scott F.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    We are developing a novel technique with which we will grow protein crystals in very small volumes, utilizing chip-based, microfluidic ("LabChip") technology. This development, which is a collaborative effort between NASA's Marshall Space Flight Center and Caliper Technologies Corporation, promises a breakthrough in the field of protein crystal growth. Our initial results obtained from two model proteins, Lysozyme and Thaumatin, show that it is feasible to dispense and adequately mix protein and precipitant solutions on a nano-liter scale. The mixtures have shown crystal growth in volumes in the range of 10 nanoliters to 5 microliters. In addition, large diffraction quality crystals were obtained by this method. X-ray data from these crystals were shown to be of excellent quality. Our future efforts will include the further development of protein crystal growth with LabChip(trademark) technology for more complex systems. We will initially address the batch growth method, followed by the vapor diffusion method and the liquid-liquid diffusion method. The culmination of these chip developments is to lead to an on orbit protein crystallization facility on the International Space Station. Structural biologists will be invited to utilize the on orbit Iterative Biological Crystallization facility to grow high quality macromolecular crystals in microgravity.

  10. Crystallization and evaluation of hen egg-white lysozyme crystals for protein pH titration in the crystalline state.

    Science.gov (United States)

    Iwai, Wakari; Yagi, Daichi; Ishikawa, Takuya; Ohnishi, Yuki; Tanaka, Ichiro; Niimura, Nobuo

    2008-05-01

    To observe the ionized status of the amino acid residues in proteins at different pH (protein pH titration in the crystalline state) by neutron diffraction, hen egg-white lysozyme was crystallized over a wide pH range (2.5-8.0). Crystallization phase diagrams at pH 2.5, 6.0 and 7.5 were determined. At pH diagram, and at pH > 4.5 the border shifted to the right (higher precipitant concentration). The qualities of these crystals were characterized using the Wilson plot method. The qualities of all crystals at different pH were more or less equivalent (B-factor values within 25-40). It is expected that neutron diffraction analysis of these crystals of different pH provides equivalent data in quality for discussions of protein pH titration in the crystalline state of hen egg-white lysozyme.

  11. CCDC 1408042: Experimental Crystal Structure Determination : 6,13-dimesitylpentacene

    KAUST Repository

    Shi, Xueliang

    2015-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  12. CCDC 1416891: Experimental Crystal Structure Determination : Methyl-triphenyl-germanium

    KAUST Repository

    Bernatowicz, Piotr

    2015-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  13. Scintillation crystal mounting apparatus

    International Nuclear Information System (INIS)

    Engdahl, L.W.; Deans, A.J.

    1982-01-01

    An improved detector head for a gamma camera is disclosed. The detector head includes a housing and a detector assembly mounted within the housing. Components of the detector assembly include a crystal sub-assembly, a phototube array, and a light pipe between the phototube array and crystal sub-assembly. The invention provides a unique structure for maintaining the phototubes in optical relationship with the light pipe and preventing the application of forces that would cause the camera's crystal to crack

  14. CMS lead tungstate crystals

    CERN Multimedia

    Laurent Guiraud

    2000-01-01

    These crystals are made from lead tungstate, a crystal that is as clear as glass yet with nearly four times the density. They have been produced in Russia to be used as scintillators in the electromagnetic calorimeter on the CMS experiment, part of the LHC project at CERN. When an electron, positron or photon passes through the calorimeter it will cause a cascade of particles that will then be absorbed by these scintillating crystals, allowing the particle's energy to be measured.

  15. Crystallization and evaluation of hen egg-white lysozyme crystals for protein pH titration in the crystalline state

    International Nuclear Information System (INIS)

    Iwai, Wakari; Yagi, Daichi; Ishikawa, Takuya; Ohnishi, Yuki; Tanaka, Ichiro; Niimura, Nobuo

    2008-01-01

    Hen egg-white lysozyme was crystallized over a wide pH range (2.5–8.0) and the quality of the crystals was characterized. Crystallization phase diagrams at pH 2.5, 6.0 and 7.5 were determined To observe the ionized status of the amino acid residues in proteins at different pH (protein pH titration in the crystalline state) by neutron diffraction, hen egg-white lysozyme was crystallized over a wide pH range (2.5–8.0). Crystallization phase diagrams at pH 2.5, 6.0 and 7.5 were determined. At pH < 4.5 the border between the metastable region and the nucleation region shifted to the left (lower precipitant concentration) in the phase diagram, and at pH > 4.5 the border shifted to the right (higher precipitant concentration). The qualities of these crystals were characterized using the Wilson plot method. The qualities of all crystals at different pH were more or less equivalent (B-factor values within 25–40). It is expected that neutron diffraction analysis of these crystals of different pH provides equivalent data in quality for discussions of protein pH titration in the crystalline state of hen egg-white lysozyme

  16. Active Photonic Crystal Waveguides

    DEFF Research Database (Denmark)

    Ek, Sara

    This thesis deals with the fabrication and characterization of active photonic crystal waveguides, realized in III-V semiconductor material with embedded active layers. The platform offering active photonic crystal waveguides has many potential applications. One of these is a compact photonic...... due to photonic crystal dispersion. The observations are explained by the enhancement of net gain by light slow down. Another application based on active photonic crystal waveguides is micro lasers. Measurements on quantum dot micro laser cavities with different mirror configurations and photonic...

  17. A crystal barrel

    CERN Multimedia

    2007-01-01

    The production of crystals for the barrel of the CMS electromagnetic calorimeter has been completed. This is an important milestone for the experiment, which received the last of its 62,960 crystals on 9 March. The members of the team responsible for the crystal acceptance testing at CERN display the last crystal for the CMS electromagnetic calorimeter barrel. From left to right: Igor Tarasov, Etiennette Auffray and Hervé Cornet.One of the six machines specially developed to measure 67 different parameters on each crystal. Igor Tarasov is seen inserting the last batch of crystals into the machine. The last of the 62,960 CMS barrel crystals arrived at CERN on 9 March. Once removed from its polystyrene protection, this delicate crystal, like thousands of its predecessors, will be inserted into the last of the 36 supermodules of the barrel electromagnetic calorimeter in a few days' time. This marks the end of an important chapter in an almost 15-year-long journey by the CMS crystals team, some of whose member...

  18. Crystallization Formulation Lab

    Data.gov (United States)

    Federal Laboratory Consortium — The Crystallization Formulation Lab fills a critical need in the process development and optimization of current and new explosives and energetic formulations. The...

  19. Future application of Czochralski crystal pulling for silicon

    Science.gov (United States)

    Matlcok, J. H.

    1985-08-01

    Czochralski (Cz) crystal pulling has been the predominant method used for preparing silicon single crystal for the past twenty years. The fundamental technology used has changed little. However, great strides have been made in learning how to make the crystals bigger and of better quality at ever increasing productivity rates. Currently charge sizes of 50 kg of polycrystal silicon are being used for production and crystals up to ten inches in diameter have been grown without major difficulty. The largest material actually being processed in silicon wafer form is 150 mm (6 inches) in diameter. Growing of crystals in a magnetic field has proved to be particularly useful for microscopic impurity control. Major developments in past years on equipment for Cz crystal pulling have included the automatic growth control of the diameter as well as the starting core of the crystal, the use of magnetic fields and around the crystal puller to supress convection, various recharging schemes for dopant control and the use of continuous liquid feed in the crystal puller. The latter, while far from being a reliable production process, is ideal in concept for major improvement in Cz crystal pulling. The Czochralski process will maintain its dominance of silicon crystal production for many years.

  20. Fabrication of Nanoimprint stamps for photonic crystals

    International Nuclear Information System (INIS)

    Kouba, J; Kubenz, M; Mai, A; Ropers, G; Eberhardt, W; Loechel, B

    2006-01-01

    We report on fabrication of nanoimprint stamps for fabrication of two dimensional photonic crystals in visible range of spectra. Nanoimprint stamps made of silicon and/or nickel were successfully fabricated using electron beam lithography and advanced dry etching techniques. The quality of the stamps was evaluated using scanning electron microscopy. The fabricated stamps were also evaluated by imprinting them into suitable polymer materials

  1. Vectorial analysis of dielectric photonic crystal VCSEL

    DEFF Research Database (Denmark)

    Chung, Il-Sug; Mørk, Jesper

    2009-01-01

    A new vertical-cavity surface-emitting laser structure employing a dielectric photonic crystal mirror has been suggested and been numerically investigated. The new structure has a smaller threshold gain, a moderate strength of single-transverse-mode operation, a high quality of emission beam free...

  2. Crystallization Process of Protein Rv0731c from Mycobacterium Tuberculosis for a Successful Atomic Resolution Crystal Structure at 1.2 Angstrom

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Liang Cong

    2009-06-08

    Proteins are bio-macromolecules consisting of basic 20 amino acids and have distinct three-dimensional folds. They are essential parts of organisms and participate in every process within cells. Proteins are crucial for human life, and each protein within the body has a specific function, such as antibodies, contractile proteins, enzymes, hormonal proteins, structural proteins, storage proteins and transport proteins. Determining three-dimensional structure of a protein can help researchers discover the remarkable protein folding, binding site, conformation and etc, in order to understand well of protein interaction and aid for possible drug design. The research on protein structure by X-ray protein crystallography carried by Li-Wei Hung's research group in the Physical Bioscience Division at Lawrence Berkeley National Laboratory (LBNL) is focusing on protein crystallography. The research in this lab is in the process of from crystallizing the proteins to determining the three dimensional crystal structures of proteins. Most protein targets are selected from Mycobacterium Tuberculosis. TB (Tuberculosis) is a possible fatal infectious disease. By studying TB target protein can help discover antituberculer drugs, and find treatment for TB. The high-throughput mode of crystallization, crystal harvesting, crystal screening and data collection are applied to the research pipeline (Figure 1). The X-ray diffraction data by protein crystals can be processed and analyzed to result in a three dimensional representation of electron density, producing a detailed model of protein structure. Rv0731c is a conserved hypothetical protein with unknown function from Mycobacterium Tuberculosis. This paper is going to report the crystallization process and brief structure information of Rv0731c.

  3. Time-resolved Laue diffraction from protein crystals: Instrumental considerations

    International Nuclear Information System (INIS)

    Bilderback, D.H.; Cornell Univ., Ithaca, NY; Moffat, K.; Szebenyi, D.M.E.

    1984-01-01

    A serious limitation of macromolecular crystallography has been its inability to determine changes in structure on a biochemical time scale of milliseconds or less. Recently, we have shown that X-ray exposures on single crystals of macromolecules may be obtained in the millisecond time range through the use of intense, polychromatic radiation with Δlambda/lambda approx.= 0.2 derived from the Cornell High Energy Synchrotron Source, CHESS. Such radiation falling on a stationary crystal yields a Laue diffraction pattern, in which almost all Laue reflections arise from a unique set of Miller indices and where their intensities are automatically integrated over wavelength. This Laue technique requires wide band pass optics, which may be obtained by a combination of reflection and transmission mirrors, filters or layered synthetic microstructures. Time-resolved macromolecular crystallography may be achieved by several data collection schemes: 'one-shot' recording coupled to a simple streak camera, repetitive sample perturbation coupled to a detector with temporal resolution and repetitive perturbation which uses the synchrotron pulses for stroboscopic triggering and detection. These schemes are appropriate for different time scales, roughly the milli-, micro- and nanosecond regimes. It appears that time-resolved crystallography is entirely feasible, with an ultimate time resolution limited only by the length of a synchrotron light pulse, some 150 ps at CHESS. (orig.)

  4. Crystal growth of various ruthenates

    Energy Technology Data Exchange (ETDEWEB)

    Kunkemoeller, Stefan; Braden, Markus [II. Physikalisches Institut, Universitaet zu Koeln (Germany); Nugroho, Agung [Institut Teknologi Bandung (Indonesia)

    2013-07-01

    Ruthenates of the Ruddlesdon-Popper series exhibit a variety of interesting phenomena ranging from unconventional superconductivity to orbitally polarized Mott insulators. Unfortunately the crystal growth of most of these ruthenates is extremely difficult partially due to the high evaporation of ruthenium; this strongly limits the research on these fascinating materials. We have started to grow single crystals of layered and perovskite ruthenates by the travelling floating-zone method using a Canon SC1-MDH mirror furnace. For the layered Ca{sub 2-x}Sr{sub x}RuO{sub 4} series we focused first on the range of concentration where recent My-SR experiments reveal spin-density wave ordering to occur at relatively high temperature and with a sizeable ordered moment. Good quality crystals of Ca{sub 1.5}Sr{sub 0.5}RuO{sub 4} can be obtained, when an excess of 15 percent of ruthenium is added to the initial preparation of the rod and when a high growth speed up to 40mm/h is used. Even slight modifications of the growing conditions result in large amounts of (Sr/Ca)RuO{sub 3} and (Sr/Ca){sub 3}Ru{sub 2}O{sub 7} intergrowth phases. First attempts to grow perovskite and double-layered ruthenates are discussed as well.

  5. The liquid protein phase in crystallization: a case study—intact immunoglobulins

    Science.gov (United States)

    Kuznetsov, Yurii G.; Malkin, Alexander J.; McPherson, Alexander

    2001-11-01

    A common observation by protein chemists has been the appearance, for many proteins in aqueous solutions, of oil like droplets, or in more extreme cases the formation of a second oil like phase. These may accompany the formation of precipitate in "salting out" or "salting in' procedures, but more commonly appear in place of any precipitate. Such phase separations also occur, with even greater frequency, in the presence of polymeric precipitants such as polyethyleneglycol (PEG). In general the appearance of a second liquid phase has been taken as indicative of protein aggregation, though an aggregate state distinctly different from that characteristic of amorphous precipitate. While the latter is thought to be composed of linear and branched assemblies, polymers of a sort, the oil phase suggests a more compact, three-dimensional, but fluid state. An important property of an alternate, fluid phase is that it can mediate transitions between other states, for example, between protein molecules free in solution and protein molecules immobilized in amorphous precipitate or crystals. The "liquid protein" phase can be readily observed in many crystallization experiments either prior to the appearance of visible crystals, or directly participating in the crystal growth process. In some cases the relationship between the liquid phase and developing crystals is intimate. Crystals grow directly from the liquid phase, or appear only after the visible formation of the liquid phase. We describe here our experience with a class of macromolecules, immunoglobulins, and particularly IDEC-151, an IgG specific for CD4 on human lymphocytes. This protein has been crystallized from a Jeffamine-LiSO 4 mother liquor and, its crystallization illustrates many of the features associated with the liquid protein, or protein rich phase.

  6. Monolayer atomic crystal molecular superlattices

    Science.gov (United States)

    Wang, Chen; He, Qiyuan; Halim, Udayabagya; Liu, Yuanyue; Zhu, Enbo; Lin, Zhaoyang; Xiao, Hai; Duan, Xidong; Feng, Ziying; Cheng, Rui; Weiss, Nathan O.; Ye, Guojun; Huang, Yun-Chiao; Wu, Hao; Cheng, Hung-Chieh; Shakir, Imran; Liao, Lei; Chen, Xianhui; Goddard, William A., III; Huang, Yu; Duan, Xiangfeng

    2018-03-01

    Artificial superlattices, based on van der Waals heterostructures of two-dimensional atomic crystals such as graphene or molybdenum disulfide, offer technological opportunities beyond the reach of existing materials. Typical strategies for creating such artificial superlattices rely on arduous layer-by-layer exfoliation and restacking, with limited yield and reproducibility. The bottom-up approach of using chemical-vapour deposition produces high-quality heterostructures but becomes increasingly difficult for high-order superlattices. The intercalation of selected two-dimensional atomic crystals with alkali metal ions offers an alternative way to superlattice structures, but these usually have poor stability and seriously altered electronic properties. Here we report an electrochemical molecular intercalation approach to a new class of stable superlattices in which monolayer atomic crystals alternate with molecular layers. Using black phosphorus as a model system, we show that intercalation with cetyl-trimethylammonium bromide produces monolayer phosphorene molecular superlattices in which the interlayer distance is more than double that in black phosphorus, effectively isolating the phosphorene monolayers. Electrical transport studies of transistors fabricated from the monolayer phosphorene molecular superlattice show an on/off current ratio exceeding 107, along with excellent mobility and superior stability. We further show that several different two-dimensional atomic crystals, such as molybdenum disulfide and tungsten diselenide, can be intercalated with quaternary ammonium molecules of varying sizes and symmetries to produce a broad class of superlattices with tailored molecular structures, interlayer distances, phase compositions, electronic and optical properties. These studies define a versatile material platform for fundamental studies and potential technological applications.

  7. Thermotropic Ionic Liquid Crystals

    Science.gov (United States)

    Axenov, Kirill V.; Laschat, Sabine

    2011-01-01

    The last five years’ achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed. PMID:28879986

  8. Thermotropic Ionic Liquid Crystals.

    Science.gov (United States)

    Axenov, Kirill V; Laschat, Sabine

    2011-01-14

    The last five years' achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed.

  9. Thermotropic Ionic Liquid Crystals

    OpenAIRE

    Axenov, Kirill V.; Laschat, Sabine

    2011-01-01

    The last five years’ achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed.

  10. Photonic crystal fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Hansen, K P; Nielsen, M D

    2003-01-01

    Photonic crystal fibers having a complex microstructure in the transverse plane constitute a new and promising class of optical fibers. Such fibers can either guide light through total internal reflection or the photonic bandgap effect, In this paper, we review the different types and applications...... of photonic crystal fibers with particular emphasis on recent advances in the field....

  11. Tactical Miniature Crystal Oscillator.

    Science.gov (United States)

    1980-08-01

    manufactured by this process are expected to require 30 days to achieve minimum aging rates. (4) FUNDEMENTAL CRYSTAL RETRACE MEASUREMENT. An important crystal...considerable measurement time to detect differences and characterize components. Before investing considerable time in a candidate reactive element, a

  12. Crystals in the LHC

    CERN Multimedia

    Antonella Del Rosso

    2012-01-01

    Bent crystals can be used to deflect charged particle beams. Their use in high-energy accelerators has been investigated for almost 40 years. Recently, a bent crystal was irradiated for the first time in the HiRadMat facility with an extreme particle flux, which crystals would have to withstand in the LHC. The results were very encouraging and confirmed that this technology could play a major role in increasing the beam collimation performance in future upgrades of the machine.   UA9 bent crystal tested with a laser. Charged particles interacting with a bent crystal can be trapped in channelling states and deflected by the atomic planes of the crystal lattice (see box). The use of bent crystals for beam manipulation in particle accelerators is a concept that has been well-assessed. Over the last three decades, a large number of experimental findings have contributed to furthering our knowledge and improving our ability to control crystal-particle interactions. In modern hadron colliders, su...

  13. Protein surface shielding agents in protein crystallization

    International Nuclear Information System (INIS)

    Hašek, J.

    2011-01-01

    The crystallization process can be controlled by protein surface shielding agents blocking undesirable competitive adhesion modes during non-equilibrium processes of deposition of protein molecules on the surface of growing crystalline blocks. The hypothesis is based on a number of experimental proofs from diffraction experiments and also retrieved from the Protein Data Bank. The molecules adhering temporarily on the surface of protein molecules change the propensity of protein molecules to deposit on the crystal surface in a definite position and orientation. The concepts of competitive adhesion modes and protein surface shielding agents acting on the surface of molecules in a non-equilibrium process of protein crystallization provide a useful platform for the control of crystallization. The desirable goal, i.e. a transient preference of a single dominating adhesion mode between protein molecules during crystallization, leads to uniform deposition of proteins in a crystal. This condition is the most important factor for diffraction quality and thus also for the accuracy of protein structure determination. The presented hypothesis is a generalization of the experimentally well proven behaviour of hydrophilic polymers on the surface of protein molecules of other compounds

  14. Influence of magnetic field on the morphology of the andrographolide crystal from supercritical carbon dioxide extraction crystallization

    Science.gov (United States)

    Chen, Kexun; Zhang, Xingyuan; Pan, Jian; Zhang, Wencheng; Yong, Ji; Yin, Wenhong

    2003-10-01

    In this paper, a supercritical fluid extraction-crystallization of andrographolide, a kind of Chinese traditional medicine, was investigated. We have studied the extraction-crystallization process with or without magnet in the extractor, respectively. It was found that the presence of magnetic field is an important factor influencing the quality of the products. SEM images showed that the crystal was slice-like in shape, and many slices reunited together in the absence of magnet. Further research showed that pressure had a certain effect on the morphology of the crystal.

  15. Optically Anomalous Crystals

    CERN Document Server

    Shtukenberg, Alexander; Kahr, Bart

    2007-01-01

    Optical anomalies in crystals are puzzles that collectively constituted the greatest unsolved problems in crystallography in the 19th Century. The most common anomaly is a discrepancy between a crystal’s symmetry as determined by its shape or by X-ray analysis, and that determined by monitoring the polarization state of traversing light. These discrepancies were perceived as a great impediment to the development of the sciences of crystals on the basis of Curie’s Symmetry Principle, the grand organizing idea in the physical sciences to emerge in the latter half of the 19th Century. Optically Anomalous Crystals begins with an historical introduction covering the contributions of Brewster, Biot, Mallard, Brauns, Tamman, and many other distinguished crystallographers. From this follows a tutorial in crystal optics. Further chapters discuss the two main mechanisms of optical dissymmetry: 1. the piezo-optic effect, and 2. the kinetic ordering of atoms. The text then tackles complex, inhomogeneous crystals, and...

  16. Progress on photonic crystals

    CERN Document Server

    Lecoq, P; Gundacker, S; Hillemanns, H; Jarron, P; Knapitsch, A; Leclercq, J L; Letartre, X; Meyer, T; Pauwels, K; Powolny, F; Seassal, C

    2010-01-01

    The renewal of interest for Time of Flight Positron Emission Tomography (TOF PET) has highlighted the need for increasing the light output of scintillating crystals and in particular for improving the light extraction from materials with a high index of refraction. One possible solution to overcome the problem of total internal reflection and light losses resulting from multiple bouncing within the crystal is to improve the light extraction efficiency at the crystal/photodetector interface by means of photonic crystals, i.e. media with a periodic modulation of the dielectric constant at the wavelength scale. After a short reminder of the underlying principles this contribution proposes to present the very encouraging results we have recently obtained on LYSO pixels and the perspectives on other crystals such as BGO, LuYAP and LuAG. These results confirm the impressive predictions from our previously published Monte Carlo simulations. A detailed description of the sample preparation procedure is given as well ...

  17. Patterning of Perovskite Single Crystals

    KAUST Repository

    Corzo, Daniel

    2017-06-12

    As the internet-of-things hardware integration continues to develop and the requirements for electronics keep diversifying and expanding, the necessity for specialized properties other than the classical semiconductor performance becomes apparent. The success of emerging semiconductor materials depends on the manufacturability and cost as much as on the properties and performance they offer. Solution-based semiconductors are an emerging concept that offers the advantage of being compatible with large-scale manufacturing techniques and have the potential to yield high-quality electronic devices at a lower cost than currently available solutions. In this work, patterns of high-quality MAPbBr3 perovskite single crystals in specific locations are achieved through the modification of the substrate properties and solvent engineering. The fabrication of the substrates involved modifying the surface adhesion forces through functionalization with self-assembled monolayers and patterning them by photolithography processes. Spin coating and blade coating were used to deposit the perovskite solution on the modified silicon substrates. While single crystal perovskites were obtained with the modification of substrates alone, solvent engineering helped with improving the Marangoni flows in the deposited droplets by increasing the contact angle and lowering the evaporation rate, therefore controlling and improving the shape of the grown perovskite crystals. The methodology is extended to other types of perovskites such as the transparent MAPbCl3 and the lead-free MABi2I9, demonstrating the adaptability of the process. Adapting the process to electrode arrays opened up the path towards the fabrication of optoelectronic devices including photodetectors and field-effect transistors, for which the first iterations are demonstrated. Overall, manufacturing and integration techniques permitting the fabrication of single crystalline devices, such as the method in this thesis work, are

  18. The contribution of polystyrene nanospheres towards the crystallization of proteins.

    Directory of Open Access Journals (Sweden)

    Johanna M Kallio

    Full Text Available BACKGROUND: Protein crystallization is a slow process of trial and error and limits the amount of solved protein structures. Search of a universal heterogeneous nucleant is an effort to facilitate crystallizability of proteins. METHODOLOGY: The effect of polystyrene nanospheres on protein crystallization were tested with three commercial proteins: lysozyme, xylanase, xylose isomerase, and with five research target proteins: hydrophobins HFBI and HFBII, laccase, sarcosine dimethylglycine N-methyltransferase (SDMT, and anti-testosterone Fab fragment 5F2. The use of nanospheres both in screening and as an additive for known crystallization conditions was studied. In screening, the addition of an aqueous solution of nanosphere to the crystallization drop had a significant positive effect on crystallization success in comparison to the control screen. As an additive in hydrophobin crystallization, the nanospheres altered the crystal packing, most likely due to the amphiphilic nature of hydrophobins. In the case of laccase, nanospheres could be used as an alternative for streak-seeding, which insofar had remained the only technique to produce high-diffracting crystals. With methyltransferase SDMT the nanospheres, used also as an additive, produced fewer, larger crystals in less time. Nanospheres, combined with the streak-seeding method, produced single 5F2 Fab crystals in shorter equilibration times. CONCLUSIONS: All in all, the use of nanospheres in protein crystallization proved to be beneficial, both when screening new crystallization conditions to promote nucleation and when used as an additive to produce better quality crystals, faster. The polystyrene nanospheres are easy to use, commercially available and close to being inert, as even with amphiphilic proteins only the crystal packing is altered and the nanospheres do not interfere with the structure and function of the protein.

  19. Effect of α-tocopherol, butylated-hydroxytoluene and hydroxy-anisole on the activation and binding of aflatoxin B1 to macromolecules

    International Nuclear Information System (INIS)

    Ch'ih, J.J.; Biedrzycka, D.; Devlin, T.M.

    1987-01-01

    The anti-oxidants, α-tocopherol(TPA), butylated-hydroxy-toluene(BHT) and hydroxyanisole(BHA) inhibit the carcinogenic and toxic effects of a variety of chemical compounds, their effect on aflatoxin B 1 (AFB 1 ) activation and binding was examined utilizing rat liver microsomes and cells. With a NADPH generating system, oxygen, microsomes, [ 3 H]-AFB 1 , 2.2 pmoles/h/mg protein was activated and bound to macromolecules. In hepatocytes, 3.4 and 1.4 pmoles of AFB 1 per 10 6 cells were taken up and bound to macromolecules, whereas the nucleic acid fraction contained 0.19 pmoles of bound AFB 1 . Moderate decreases of AFB 1 activation and binding were observed when TPA was present in both cell-free and hepatocytes systems. Only in hepatocytes, BHT inhibited the AFB 1 uptake and binding to nucleic acids. BHA, however, inhibited microsomal activation of AFB 1 by 73%; maximum inhibition was reached at 1 mM. AFB 1 uptake, and binding to nucleic acids were inhibited by 65% and 79% by BHA. GSH-transferase activity of cells treated with these agents was not altered. The effect of BHA at various concentrations on AFB activation was compared with cytochrome P-450 inhibitors; the ED 50 of SKF 525A, BHA and metyrapone was 9 uM, 80 uM and 380 uM respectively. The data suggest that TPA, BHA and BHT exert their effect by different mechanisms

  20. Surface engineering of nanoparticles with macromolecules for epoxy curing: Development of super-reactive nitrogen-rich nanosilica through surface chemistry manipulation

    Science.gov (United States)

    Jouyandeh, Maryam; Jazani, Omid Moini; Navarchian, Amir H.; Shabanian, Meisam; Vahabi, Henri; Saeb, Mohammad Reza

    2018-07-01

    Curing behavior of epoxy-based nanocomposites depends on dispersion state of nanofillers and their physical and chemical interactions with the curing moieties. In this work, a systematic approach was introduced for chemical functionalization of nanoparticles with macromolecules in order to enrich crosslinking potential of epoxy/amine systems, particularly at late stages of cure where the curing is diffusion-controlled. Super-reactive hyperbranched polyethylenimine (PEI)-attached nanosilica was materialized in this work to facilitate epoxy-amine curing. Starting from coupling [3-(2,3-epoxypropoxy) propyl] trimethoxysilane (EPPTMS) with hyperbranched PEI, a super-reactive macromolecule was obtained and subsequently grafted onto the nanosilica surface. Eventually, a thermally-stable highly-curable nanocomposite was attained by replacement of amine and imine groups of the PEI with imide and amide groups through the reaction with pyromellitic acid dianhydride. Fourier-transform infrared spectrophotometry, X-ray diffractometry, X-ray photoelectron spectroscopy and transmission electron microscopy approved successful grafting of polymer chains onto the nanosilica surface. Thermogravimetric analyses approved a relatively high grafting ratio of ca. 21%. Curing potential of the developed super-reactive nanoparticle was uncovered through nonisothermal differential scanning calorimetry signifying an enthalpy rise of ca. 120 J/g by addition of 2 wt.% to epoxy at 5 °C/min heating rate. Even at low concentration of 0.5 wt.%, the glass transition temperature of epoxy increased from 128 to 156 °C, demonstrating prolonged crosslinking.

  1. A polymeric micelle magnetic resonance imaging (MRI) contrast agent reveals blood-brain barrier (BBB) permeability for macromolecules in cerebral ischemia-reperfusion injury.

    Science.gov (United States)

    Shiraishi, Kouichi; Wang, Zuojun; Kokuryo, Daisuke; Aoki, Ichio; Yokoyama, Masayuki

    2017-05-10

    Blood-brain barrier (BBB) opening is a key phenomenon for understanding ischemia-reperfusion injuries that are directly linked to hemorrhagic transformation. The recombinant human tissue-type plasminogen activator (rtPA) increases the risk of symptomatic intracranial hemorrhages. Recent imaging technologies have advanced our understanding of pathological BBB disorders; however, an ongoing challenge in the pre-"rtPA treatment" stage is the task of developing a rigorous method for hemorrhage-risk assessments. Therefore, we examined a novel method for assessment of rtPA-extravasation through a hyper-permeable BBB. To examine the image diagnosis of rtPA-extravasation for a rat transient occlusion-reperfusion model, in this study we used a polymeric micelle MRI contrast-agent (Gd-micelles). Specifically, we used two MRI contrast agents at 1h after reperfusion. Gd-micelles provided very clear contrast images in 15.5±10.3% of the ischemic hemisphere at 30min after i.v. injection, whereas a classic gadolinium chelate MRI contrast agent provided no satisfactorily clear images. The obtained images indicate both the hyper-permeable BBB area for macromolecules and the distribution area of macromolecules in the ischemic hemisphere. Owing to their large molecular weight, Gd-micelles remained in the ischemic hemisphere through the hyper-permeable BBB. Our results indicate the feasibility of a novel clinical diagnosis for evaluating rtPA-related hemorrhage risks. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Molar mass, radius of gyration and second virial coefficient from new static light scattering equations for dilute solutions: application to 21 (macro)molecules.

    Science.gov (United States)

    Illien, Bertrand; Ying, Ruifeng

    2009-05-11

    New static light scattering (SLS) equations for dilute binary solutions are derived. Contrarily to the usual SLS equations [Carr-Zimm (CZ)], the new equations have no need for the experimental absolute Rayleigh ratio of a reference liquid and solely rely on the ratio of scattered intensities of solutions and solvent. The new equations, which are based on polarizability equations, take into account the usual refractive index increment partial differential n/partial differential rho(2) complemented by the solvent specific polarizability and a term proportional to the slope of the solution density rho versus the solute mass concentration rho(2) (density increment). Then all the equations are applied to 21 (macro)molecules with a wide range of molar mass (0.2equations clearly achieve a better agreement with supplier M values. For macromolecules (M>500 kg mol(-1)), for which the scattered intensity is no longer independent of the scattering angle, the new equations give the same value of the radius of gyration as the CZ equation and consistent values of the second virial coefficient.

  3. The anchorless adhesin Eap (extracellular adherence protein) from Staphylococcus aureus selectively recognizes extracellular matrix aggregates but binds promiscuously to monomeric matrix macromolecules.

    Science.gov (United States)

    Hansen, Uwe; Hussain, Muzaffar; Villone, Daniela; Herrmann, Mathias; Robenek, Horst; Peters, Georg; Sinha, Bhanu; Bruckner, Peter

    2006-05-01

    Besides a number of cell wall-anchored adhesins, the majority of Staphylococcus aureus strains produce anchorless, cell wall-associated proteins, such as Eap (extracellular adherence protein). Eap contains four to six tandem repeat (EAP)-domains. Eap mediates diverse biological functions, including adherence and immunomodulation, thus contributing to S. aureus pathogenesis. Eap binding to host macromolecules is unusually promiscuous and includes matrix or matricellular proteins as well as plasma proteins. The structural basis of this promiscuity is poorly understood. Here, we show that in spite of the preferential location of the binding epitopes within triple helical regions in some collagens there is a striking specificity of Eap binding to different collagen types. Collagen I, but not collagen II, is a binding substrate in monomolecular form. However, collagen I is virtually unrecognized by Eap when incorporated into banded fibrils. By contrast, microfibrils containing collagen VI as well as basement membrane-associated networks containing collagen IV, or aggregates containing fibronectin bound Eap as effectively as the monomeric proteins. Therefore, Eap-binding to extracellular matrix ligands is promiscuous at the molecular level but not indiscriminate with respect to supramolecular structures containing the same macromolecules. In addition, Eap bound to banded fibrils after their partial disintegration by matrix-degrading proteinases, including matrix metalloproteinase 1. Therefore, adherence to matrix suprastructures by S. aureus can be supported by inflammatory reactions.

  4. Crystallization and preliminary X-ray crystallographic analysis of β-galactosidase from Kluyveromyces lactis

    International Nuclear Information System (INIS)

    Pereira-Rodríguez, Ángel; Fernández-Leiro, Rafael; González Siso, M. Isabel; Cerdán, M. Esperanza; Becerra, Manuel; Sanz-Aparicio, Julia

    2010-01-01

    β-Galactosidase from K. lactis has been expressed in S. cerevisiae, purified by affinity chromatography and crystallized in its native form. β-Galactosidase from Kluyveromyces lactis catalyses the hydrolysis of the β-galactosidic linkage in lactose. Owing to its many industrial applications, the biotechnological potential of this enzyme is substantial. This protein has been expressed in yeast and purified for crystallization trials. However, optimization of the best crystallization conditions yielded crystals with poor diffraction quality that precluded further structural studies. Finally, the crystal quality was improved using the streak-seeding technique and a complete diffraction data set was collected at 2.8 Å resolution

  5. Influence of impurities on the surface morphology of the TIBr crystal semiconductor

    International Nuclear Information System (INIS)

    Santos, Robinson A. dos; Silva, Julio B. Rodrigues da; Martins, Joao F.T.; Ferraz, Caue de M.; Costa, Fabio E. da; Mesquita, Carlos H. de; Hamada, Margarida M.; Gennari, Roseli F.

    2013-01-01

    The impurity effect in the surface morphology quality of TlBr crystals was evaluated, aiming a future application of these crystals as room temperature radiation semiconductor detectors. The crystals were purified and grown by the Repeated Bridgman technique. Systematic measurements were carried out for determining the stoichiometry, structure orientation, surface morphology and impurity of the crystal. A significant difference in the crystals impurity concentration was observed for almost all impurities, compared to those found in the raw material. The crystals wafer grown twice showed a surface roughness and grains which may be due to the presence of impurities on the surface, while those obtained with crystals grown three times presented a more uniform surface: even though, a smaller roughness was still observed. It was demonstrated that the impurities affect strongly the surface morphology quality of crystals. (author)

  6. Synchrotron White Beam X-Ray Topography Characterization of LGX and SXGS Bulk Single Crystals, Thin Films and Piezoelectric Devices

    National Research Council Canada - National Science Library

    Dudley, Michael

    2007-01-01

    ...), to the determination of defect and general distortion distributions in novel LGX piezoelectric crystals with a view to enabling improvement in crystal quality and consequently in piezoelectric device performance...

  7. From Atomic Resolution to Molecular Giants: an Overview of Crystallographic Studies of Biological Macromolecules with Synchrotron Radiation

    International Nuclear Information System (INIS)

    Jaskolski, M.

    2010-01-01

    Protein crystals have huge unit cells ( ≅100 A) filled not only with ordered protein molecules but also in about 50% with liquid water. The phase problem in protein crystallography can be solved by molecular replacement (using a suitable model molecule), by isomorphous replacement (using heavy atom derivatives), or by multiwavelength anomalous diffraction (using resonant scattering of synchrotron-generated X-rays by anomalous atoms, such as Se). X-ray diffraction by protein crystals produces thousands of reflections but since the models are very complex (many thousands of atoms), paucity of data is a serious problem and stereochemical restraints are necessary. In consequence, the highest possible resolution (minimum d-spacing in Bragg's Equation) should always be the experimental goal. Protein structures determined by crystallography are deposited in protein data bank, which currently holds more than 62000 entries. Recent methodological advancements, stimulated by a wide-spread use of powerful synchrotron sources and by structural genomics, have resulted in rapid acceleration of the structure elucidation process, and in addition help to obtain a better data. Protein crystallography has produced atomic models of gigantic macromolecular assemblies, including the ribosome. It is also providing accurate targets for structure-guided development of drugs. (author)

  8. From atomic resolution to molecular giants: an overview of crystallographic studies of biological macromolecules with synchrotron radiation

    International Nuclear Information System (INIS)

    Jaskolski, M.

    2010-01-01

    Protein crystals have huge unit cells (∼ 100 A) filled not only with ordered protein molecules but also in about 50% with liquid water. The phase problem in protein crystallography can be solved by molecular replacement (using a suitable model molecule), by isomorphous replacement (using heavy atom derivatives), or by multiwavelength anomalous diffraction (using resonant scattering of synchrotron-generated X-rays by anomalous atoms, such as Se). X-ray diffraction by protein crystals produces thousands of reflections but since the models are very complex (many thousands of atoms), paucity of data is a serious problem and stereochemical restraints are necessary. In consequence, the highest possible resolution (minimum d-spacing in Bragg's Equation) should always be the experimental goal. Protein structures determined by crystallography are deposited in Protein Data Bank, which currently holds more than 65 000 entries. Recent methodological advancements, stimulated by a wide-spread use of powerful synchrotron sources and by structural genomics, have resulted in rapid acceleration of the structure elucidation process, and in addition help to obtain better data. Protein crystallography has produced atomic models of gigantic macromolecular assemblies, including the ribosome. It is also providing accurate targets for structure-guided development of drugs. (author)

  9. Disorder in Protein Crystals.

    Science.gov (United States)

    Clarage, James Braun, II

    1990-01-01

    Methods have been developed for analyzing the diffuse x-ray scattering in the halos about a crystal's Bragg reflections as a means of determining correlations in atomic displacements in protein crystals. The diffuse intensity distribution for rhombohedral insulin, tetragonal lysozyme, and triclinic lysozyme crystals was best simulated in terms of exponential displacement correlation functions. About 90% of the disorder can be accounted for by internal movements correlated with a decay distance of about 6A; the remaining 10% corresponds to intermolecular movements that decay in a distance the order of size of the protein molecule. The results demonstrate that protein crystals fit into neither the Einstein nor the Debye paradigms for thermally fluctuating crystalline solids. Unlike the Einstein model, there are correlations in the atomic displacements, but these correlations decay more steeply with distance than predicted by the Debye-Waller model for an elastic solid. The observed displacement correlations are liquid -like in the sense that they decay exponentially with the distance between atoms, just as positional correlations in a liquid. This liquid-like disorder is similar to the disorder observed in 2-D crystals of polystyrene latex spheres, and similar systems where repulsive interactions dominate; hence, these colloidal crystals appear to provide a better analogy for the dynamics of protein crystals than perfectly elastic lattices.

  10. Fabrication of photonic crystals on several kinds of semiconductor materials by using focused-ion beam method

    International Nuclear Information System (INIS)

    Xu Xingsheng; Chen Hongda; Xiong Zhigang; Jin Aizi; Gu Changzhi; Cheng Bingying; Zhang Daozhong

    2007-01-01

    In this paper, we introduced the fabrication of photonic crystals on several kinds of semiconductor materials by using focused-ion beam machine, it shows that the method of focused-ion beam can fabricate two-dimensional photonic crystal and photonic crystal device efficiently, and the quality of the fabricated photonic crystal is high. Using the focused-ion beam method, we fabricate photonic crystal wavelength division multiplexer, and its characteristics are analyzed

  11. A Proposed Model for Protein Crystal Nucleation and Growth

    Science.gov (United States)

    Pusey, Marc; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    How does one take a molecule, strongly asymmetric in both shape and charge distribution, and assemble it into a crystal? We propose a model for the nucleation and crystal growth process for tetragonal lysozyme, based upon fluorescence, light, neutron, and X-ray scattering data, size exclusion chromatography experiments, dialysis kinetics, AFM, and modeling of growth rate data, from this and other laboratories. The first species formed is postulated to be a 'head to side' dimer. Through repeating associations involving the same intermolecular interactions this grows to a 4(sub 3) helix structure, that in turn serves as the basic unit for nucleation and subsequent crystal growth. High salt attenuates surface charges while promoting hydrophobic interactions. Symmetry facilitates subsequent helix-helix self-association. Assembly stability is enhanced when a four helix structure is obtained, with each bound to two neighbors. Only two unique interactions are required. The first are those for helix formation, where the dominant interaction is the intermolecular bridging anion. The second is the anti-parallel side-by-side helix-helix interaction, guided by alternating pairs of symmetry related salt bridges along each side. At this stage all eight unique positions of the P4(sub3)2(sub 1),2(sub 1) unit cell are filled. The process is one of a) attenuating the most strongly interacting groups, such that b) the molecules begin to self-associate in defined patterns, so that c) symmetry is obtained, which d) propagates as a growing crystal. Simple and conceptually obvious in hindsight, this tells much about what we are empirically doing when we crystallize macromolecules. By adjusting the growth parameters we are empirically balancing the intermolecular interactions, preferentially attenuating the dominant strong (for lysozyme the charged groups) while strengthening the lesser strong (hydrophobic) interactions. In the general case for proteins the lack of a singularly defined

  12. Crystals in light.

    Science.gov (United States)

    Kahr, Bart; Freudenthal, John; Gunn, Erica

    2010-05-18

    We have made images of crystals illuminated with polarized light for almost two decades. Early on, we abandoned photosensitive chemicals in favor of digital electrophotometry with all of the attendant advantages of quantitative intensity data. Accurate intensities are a boon because they can be used to analytically discriminate small effects in the presence of larger ones. The change in the form of our data followed camera technology that transformed picture taking the world over. Ironically, exposures in early photographs were presumed to correlate simply with light intensity, raising the hope that photography would replace sensorial interpretation with mechanical objectivity and supplant the art of visual photometry. This was only true in part. Quantitative imaging accurate enough to render the separation of crystalloptical quantities had to await the invention of the solid-state camera. Many pioneers in crystal optics were also major figures in the early history of photography. We draw out the union of optical crystallography and photography because the tree that connects the inventors of photography is a structure unmatched for organizing our work during the past 20 years, not to mention that silver halide crystallites used in chemical photography are among the most consequential "crystals in light", underscoring our title. We emphasize crystals that have acquired optical properties such as linear birefringence, linear dichroism, circular birefringence, and circular dichroism, during growth from solution. Other crystalloptical effects were discovered that are unique to curiously dissymmetric crystals containing embedded oscillators. In the aggregate, dyed crystals constitute a generalization of single crystal matrix isolation. Simple crystals provided kinetic stability to include guests such as proteins or molecules in excited states. Molecular lifetimes were extended for the preparation of laser gain media and for the study of the photodynamics of single

  13. Magnetic ions in crystals

    CERN Document Server

    Stevens, K W

    2014-01-01

    There have been many demonstrations, particularly for magnetic impurity ions in crystals, that spin-Hamiltonians are able to account for a wide range of experimental results in terms of much smaller numbers of parameters. Yet they were originally derived from crystal field theory, which contains a logical flaw; electrons on the magnetic ions are distinguished from those on the ligands. Thus there is a challenge: to replace crystal field theory with one of equal or greater predictive power that is based on a surer footing. The theory developed in this book begins with a generic Hamiltonian, on

  14. Silumins alloy crystallization

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2009-07-01

    Full Text Available This paper presents the results of research, by ATD method, of hypo-, near- and hyperutectic silumins crystallization containing the following alloying additives: Mg, Ni, Cu, Cr, Mo, W, V. It has been shown that, depending on their concentration may crystallize pre-eutectic or eutectic multicomponent phases containing these alloy additives. It has been revealed that any subsequent crystallizable phase nucleate and grows near the liquid/former crystallized phase interface. In multiphases compound also falls the silicon, resulting in a reduction in its quantity and the fragmentation in the eutectic mixture. As a result, it gets a high hardness of silumins in terms of 110-220HB.

  15. Crystal Structure of the 30S Ribosomal Subunit from Thermus Thermophilus: Purification, Crystallization and Structure Determination

    International Nuclear Information System (INIS)

    Clemons, William M. Jr.; Brodersen, Ditlev E.; McCutcheonn, John P.; May, Joanna L.C.; Carter, Andrew P.; Morgan-Warren, Robert J.; Wimberly, Brian T.; Ramakrishnan, Venki

    2001-01-01

    We describe the crystallization and structure determination of the 30 S ribosomal subunit from Thermus thermophilus. Previous reports of crystals that diffracted to 10 (angstrom) resolution were used as a starting point to improve the quality of the diffraction. Eventually, ideas such as the addition of substrates or factors to eliminate conformational heterogeneity proved less important than attention to detail in yielding crystals that diffracted beyond 3 (angstrom) resolution. Despite improvements in technology and methodology in the last decade, the structure determination of the 30 S subunit presented some very challenging technical problems because of the size of the asymmetric unit, crystal variability and sensitivity to radiation damage. Some steps that were useful for determination of the atomic structure were: the use of anomalous scattering from the LIII edges of osmium and lutetium to obtain the necessary phasing signal; the use of tunable, third-generation synchrotron sources to obtain data of reasonable quality at high resolution; collection of derivative data precisely about a mirror plane to preserve small anomalous differences between Bijvoet mates despite extensive radiation damage and multi-crystal scaling; the pre-screening of crystals to ensure quality, isomorphism and the efficient use of scarce third-generation synchrotron time; pre-incubation of crystals in cobalt hexaammine to ensure isomorphism with other derivatives; and finally, the placement of proteins whose structures had been previously solved in isolation, in conjunction with biochemical data on protein-RNA interactions, to map out the architecture of the 30 S subunit prior to the construction of a detailed atomic-resolution model.

  16. Molecular nucleation mechanisms and control strategies for crystal polymorph selection

    Science.gov (United States)

    van Driessche, Alexander E. S.; van Gerven, Nani; Bomans, Paul H. H.; Joosten, Rick R. M.; Friedrich, Heiner; Gil-Carton, David; Sommerdijk, Nico A. J. M.; Sleutel, Mike

    2018-04-01

    The formation of condensed (compacted) protein phases is associated with a wide range of human disorders, such as eye cataracts, amyotrophic lateral sclerosis, sickle cell anaemia and Alzheimer’s disease. However, condensed protein phases have their uses: as crystals, they are harnessed by structural biologists to elucidate protein structures, or are used as delivery vehicles for pharmaceutical applications. The physiochemical properties of crystals can vary substantially between different forms or structures (‘polymorphs’) of the same macromolecule, and dictate their usability in a scientific or industrial context. To gain control over an emerging polymorph, one needs a molecular-level understanding of the pathways that lead to the various macroscopic states and of the mechanisms that govern pathway selection. However, it is still not clear how the embryonic seeds of a macromolecular phase are formed, or how these nuclei affect polymorph selection. Here we use time-resolved cryo-transmission electron microscopy to image the nucleation of crystals of the protein glucose isomerase, and to uncover at molecular resolution the nucleation pathways that lead to two crystalline states and one gelled state. We show that polymorph selection takes place at the earliest stages of structure formation and is based on specific building blocks for each space group. Moreover, we demonstrate control over the system by selectively forming desired polymorphs through site-directed mutagenesis, specifically tuning intermolecular bonding or gel seeding. Our results differ from the present picture of protein nucleation, in that we do not identify a metastable dense liquid as the precursor to the crystalline state. Rather, we observe nucleation events that are driven by oriented attachments between subcritical clusters that already exhibit a degree of crystallinity. These insights suggest ways of controlling macromolecular phase transitions, aiding the development of protein

  17. X-ray diffraction studies on merohedrally twinned Δ1-62NtNBCe1-A crystals of the sodium/bicarbonate cotransporter.

    Science.gov (United States)

    Gill, Harindarpal S; Dutcher, Lauren; Boron, Walter F; Patel, Samir; Guay-Woodford, Lisa M

    2013-07-01

    NBCe1-A membrane-embedded macromolecules that cotransport sodium and bicarbonate ions across the bilayer serve to maintain acid-base homeostasis throughout the body. Defects result in a number of renal and eye disorders, including type-II renal tubular acidosis and cataracts. Here, crystals of a human truncated mutant of the cytoplasmic N-terminal domain of NBCe1 (Δ1-62NtNBCe1-A) are reported that diffract X-rays to 2.4 Å resolution. The crystal symmetry of Δ1-62NtNBCe1-A is of space group P31 with pseudo-P3121 symmetry and it has a hemihedral twin fraction of 33.0%. The crystals may provide insight into the pathogenic processes observed in a subset of patients with truncating and point mutations in the gene encoding NBCe1.

  18. Design and Development of a Robot-Based Automation System for Cryogenic Crystal Sample Mounting at the Advanced Photon Source

    International Nuclear Information System (INIS)

    Shu, D.; Preissner, C.; Nocher, D.; Han, Y.; Barraza, J.; Lee, P.; Lee, W.-K.; Cai, Z.; Ginell, S.; Alkire, R.; Lazarski, K.; Schuessler, R.; Joachimiak, A.

    2004-01-01

    X-ray crystallography is the primary method to determine the 3D structures of complex macromolecules at high resolution. In the years to come, the Advanced Photon Source (APS) and similar 3rd-generation synchrotron sources elsewhere will become the most powerful tools for studying atomic structures of biological molecules. One of the major bottlenecks in the x-ray data collection process is the constant need to change and realign the crystal sample. This is a very time- and manpower-consuming task. An automated sample mounting system will help to solve this bottleneck problem. We have developed a novel robot-based automation system for cryogenic crystal sample mounting at the APS. Design of the robot-based automation system, as well as its on-line test results at the Argonne Structural Biology Center (SBC) 19-BM experimental station, are presented in this paper

  19. EFFECT OF CONTINUOUS CRYSTALLIZER PERFORMANCE ON STRUVITE CRYSTALS PRODUCED IN REACTION CRYSTALLIZATION FROM SOLUTIONS CONTAINING PHOSPHATE(V AND ZINC(II IONS

    Directory of Open Access Journals (Sweden)

    N. Hutnik

    Full Text Available Abstract Continuous reaction crystallization of struvite from aqueous solutions containing phosphate(V (1.0 mass % and zinc(II ions (from 0.1 to 2.0 mg kg-1 in a continuous DT MSMPR crystallizer was investigated. The influence of pH (9 - 11 and mean residence time (900 - 3600 s on the product characteristics and its chemical composition was tested. Struvite crystals of mean size 22-41 µm were produced. An increase in Zn2+ concentration decreased the mean crystal size and homogeneity. An elevation of the pH also decreased the struvite crystal size. Augmenting the mean residence time influenced product quality advantageously. Coexistence of struvite and Zn(OH2 in the product was confirmed analytically.

  20. Crystal Genetics, Inc.

    Science.gov (United States)

    Kermani, Bahram G

    2016-07-01

    Crystal Genetics, Inc. is an early-stage genetic test company, focused on achieving the highest possible clinical-grade accuracy and comprehensiveness for detecting germline (e.g., in hereditary cancer) and somatic (e.g., in early cancer detection) mutations. Crystal's mission is to significantly improve the health status of the population, by providing high accuracy, comprehensive, flexible and affordable genetic tests, primarily in cancer. Crystal's philosophy is that when it comes to detecting mutations that are strongly correlated with life-threatening diseases, the detection accuracy of every single mutation counts: a single false-positive error could cause severe anxiety for the patient. And, more importantly, a single false-negative error could potentially cost the patient's life. Crystal's objective is to eliminate both of these error types.

  1. Diffusion in Coulomb crystals.

    Science.gov (United States)

    Hughto, J; Schneider, A S; Horowitz, C J; Berry, D K

    2011-07-01

    Diffusion in Coulomb crystals can be important for the structure of neutron star crusts. We determine diffusion constants D from molecular dynamics simulations. We find that D for Coulomb crystals with relatively soft-core 1/r interactions may be larger than D for Lennard-Jones or other solids with harder-core interactions. Diffusion, for simulations of nearly perfect body-centered-cubic lattices, involves the exchange of ions in ringlike configurations. Here ions "hop" in unison without the formation of long lived vacancies. Diffusion, for imperfect crystals, involves the motion of defects. Finally, we find that diffusion, for an amorphous system rapidly quenched from Coulomb parameter Γ=175 to Coulomb parameters up to Γ=1750, is fast enough that the system starts to crystalize during long simulation runs. These results strongly suggest that Coulomb solids in cold white dwarf stars, and the crust of neutron stars, will be crystalline and not amorphous.

  2. Bipolarons in nonmetallic crystals

    International Nuclear Information System (INIS)

    Vinetskii, V.L.; Pashitskii, E.A.; Yanchuk, V.A.

    1987-01-01

    The binding energy of a bipolaron in an ionic crystal increases substantially in the case of strong anisotropy of the effective masses of the free carriers of the easy plane type or easy axis type. In the second case the polaron is cigar-like in shape and the coaxial configuration of bipolarons is energetically favorable. In this case a significant gain in the binding energy and in the width of the region of existence of the bipolaron, with respect to the dielectric constant and the magnitude of the electron-phonon interaction constant, compared with an isotropic crystal, is obtained only for quasi-two-dimensional, or layered, and quasi-one-dimensional, or chainlike, crystals. This work shows that a significant gain in the binding energy can be obtained by taking into account the anisotropy of the dielectric constant of the crystal and localization of the electron wave functions in directions perpendicular to the layers and chains of atoms

  3. Liquid Crystal Colloids

    Science.gov (United States)

    Smalyukh, Ivan I.

    2018-03-01

    Colloids are abundant in nature, science, and technology, with examples ranging from milk to quantum dots and the colloidal atom paradigm. Similarly, liquid crystal ordering is important in contexts ranging from biological membranes to laboratory models of cosmic strings and liquid crystal displays in consumer devices. Some of the most exciting recent developments in both of these soft matter fields emerge at their interface, in the fast-growing research arena of liquid crystal colloids. Mesoscale self-assembly in such systems may lead to artificial materials and to structures with emergent physical behavior arising from patterning of molecular order and nano- or microparticles into precisely controlled configurations. Liquid crystal colloids show exceptional promise for new discovery that may impinge on composite material fabrication, low-dimensional topology, photonics, and so on. Starting from physical underpinnings, I review the state of the art in this fast-growing field, with a focus on its scientific and technological potential.

  4. Creep of crystals

    International Nuclear Information System (INIS)

    Poirier, J.-P.

    1988-01-01

    Creep mechanisms for metals, ceramics and rocks, effect of pressure and temperature on deformation processes are considered. The role of crystal defects is analysed, different models of creep are described. Deformation mechanisms maps for different materials are presented

  5. Thermotropic Ionic Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Sabine Laschat

    2011-01-01

    Full Text Available The last five years’ achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed.

  6. Building a crystal palace

    CERN Multimedia

    2007-01-01

    The end-caps of the CMS electromagnetic calorimeter (ECAL) take shape as the first quadrant was completed on Wednesday 3 October. 1831 crystals, organised into five by five blocks named ‘supercrystals’, make up the first quadrant of Dee 1.With the 61,200-crystal barrel of its electromagnetic calorimeter (ECAL) complete, CMS is now building the endcaps, on the tenth anniversary of their initial design. Crystals for the endcaps were the last to be made, so the race is now on to have them all in place and ready for the turn-on of the LHC next year. Assembly of the first of eight quadrants began in June and crystal mounting was completed on Wednesday 3 October. Each crystal is transparent, has a volume just larger than a CERN coffee cup yet weighs a huge 1.5kg. 1831 of these lead tungstate crystals went into the first quadrant from a total 14,648 in the endcaps. The lead and tungsten account for 86% of each crystal’s weight, but as project leader Dave Cockerill expl...

  7. Paleovegetation changes recorded by n-alkyl lipids bound in macromolecules of plant fossils and kerogens from the Cretaceous sediments in Japan

    Science.gov (United States)

    Miyata, Y.; Sawada, K.; Nakamura, H.; Takashima, R.; Takahashi, M.

    2014-12-01

    Resistant macromolecules composing living plant tissues tend to be preserved through degradation and diagenesis, hence constituate major parts of sedimentary plant-derived organic matter (kerogen), and their monomer compositions vary widely among different plant taxa, organs and growth stages. Thus, analysis of such macromolecule may serve as new technique for paleobotanical evaluation distinctive from classical paleobotnical studies depends on morphological preservation of fossils. In the present study, we analyzed plant fossils and kerogens in sediments from the Cretaceous strata in Japan to examine chemotaxonomic characteristics of fossil macromolecules and to reconstruct paleovegetation change by kerogen analysis. The kerogens were separated from the powdered sediments of Cretaceous Yezo Group, Hokkaido, Japan. All kerogens have been confirmed to be mostly originated from land plant tissues by microscopic observation. Mummified angiosperm and gymnosperm fossil leaves were separated from carbonaceous sandstone of the Cretaceous Ashizawa Formation, Futaba Group. The kerogens and plant fossils were extracted with methanol and dichloromethane, and were subsequently refluxed under 110°C to remove free compounds completely. The residues are hydrolyzed by KOH/methanol under 110°C. These released compounds are analyzed by GC-MS. As main hydrolyzed products (ester-bound molecular units) from all kerogens, C10-C28 n-alkanoic acids and C10-C30 n-alkanols were detected. Recent studies on the hydrolysis products of plant tissues suggested the long chain (>C20) n-alkanols were predominantly abundant in deciduous broadleaved angiosperms. Correspondingly, the stratigraphic variation of the ratios of long chain (>C20) n-alkanols to fatty acids was concordant with the variation of angiosperm/gymnosperm ratios recorded by land plant-derived terpenoid biomarkers. In addition, we found that the long chain n-alkanols/fatty acids ratio in the angiosperm fossil leaf was

  8. Coenzyme- and His-tag-induced crystallization of octopine dehydrogenase

    International Nuclear Information System (INIS)

    Smits, Sander H. J.; Mueller, Andre; Grieshaber, Manfred K.; Schmitt, Lutz

    2008-01-01

    The crystal structure of octopine dehydrogenase revealed a specific role of the His 5 tag in inducing the crystal contacts required for successful crystallization. Over the last decade, protein purification has become more efficient and standardized through the introduction of affinity tags. The choice and position of the tag, however, can directly influence the process of protein crystallization. Octopine dehydrogenase (OcDH) without a His tag and tagged protein constructs such as OcDH-His 5 and OcDH-LEHis 6 have been investigated for their crystallizability. Only OcDH-His 5 yielded crystals; however, they were multiple. To improve crystal quality, the cofactor NADH was added, resulting in single crystals that were suitable for structure determination. As shown by the structure, the His 5 tag protrudes into the cleft between the NADH and l-arginine-binding domains and is mainly fixed in place by water molecules. The protein is thereby stabilized to such an extent that the formation of crystal contacts can proceed. Together with NADH, the His 5 tag obviously locks the enzyme into a specific conformation which induces crystal growth

  9. Oxidative damage to biological macromolecules in Prague bus drivers and garagemen: Impact of air pollution and genetic polymorphisms

    Czech Academy of Sciences Publication Activity Database

    Bagryantseva, Yana; Novotná, Božena; Rössner ml., Pavel; Chvátalová, Irena; Milcová, Alena; Švecová, Vlasta; Lněničková, Zdena; Solanský, I.; Šrám, Radim

    2010-01-01

    Roč. 199, č. 1 (2010), s. 60-68 ISSN 0378-4274 R&D Projects: GA MŽP(CZ) SP/1B3/8/08 Institutional research plan: CEZ:AV0Z50390512 Keywords : air pollution * bud drivers * oxidative stress Subject RIV: DN - Health Impact of the Environment Quality Impact factor: 3.581, year: 2010

  10. Water-resistance of macromolecules adsorbed on CH3NH3PbI3 surfaces: A first-principles study

    Science.gov (United States)

    Chen, Po-Tuan; Yung, Tung-Yuan; Liu, Ting-Yu; Sher, Chin-Wei; Hayashi, Michitoshi

    2017-10-01

    Encapsulation within resin films is a promising approach for isolating perovskite materials from water. To gain fundamental insight into these systems, we performed first-principles calculations of macromolecule (polymerized siloxane; epoxy cured by phthalic anhydride; graphene sheet) coatings for the waterproofing of methylammonium lead iodide perovskite (MAPbI3) surfaces. Our calculations reveal that alternating attractive/resistant functional groups on the siloxane- or epoxy-modified MAPbI3 surfaces hinder the water diffusion process. Moreover, we examined a no-defect graphene sheet for its ability to isolate MAPbI3 from water molecules. The hydrophobicity of the graphene resulted in water molecules forming clusters, rather than dispersing, upon the sheet.

  11. Increased intestinal permeability to macromolecules and endotoxemia in patients with chronic alcohol abuse in different stages of alcohol-induced liver disease

    DEFF Research Database (Denmark)

    Parlesak, Alexandr; Schäfer, C.; Schütz, Tanja

    2000-01-01

    BACKGROUND/AIMS: No information is yet available about the influence of alcohol abuse on the translocation of larger molecules (Mr>1200) through the intestinal mucosa in man. The present study aimed to determine the intestinal permeability to macromolecules in patients with chronic alcohol abuse...... and mild to more advanced stages of liver disease, and to measure the concentration of endotoxins in the plasma, as these compounds derive from the intestinal flora and are suspected to contribute to the development of alcoholic liver disease (ALD). METHODS: The permeability to polyethylene glycol Mr 400......, Mr 1500, Mr 4000, and Mr 10,000 and endotoxin plasma concentrations were measured in 54 patients with alcoholic liver disease, 19 of them with cirrhosis, and in 30 non-alcoholic healthy controls. RESULTS: Permeability to polyethylene glycol Mr 400 was found to be unchanged in patients with ALD...

  12. Direct analysis of intact biological macromolecules by low-energy, fiber-based femtosecond laser vaporization at 1042 nm wavelength with nanospray postionization mass spectrometry.

    Science.gov (United States)

    Shi, Fengjian; Flanigan, Paul M; Archer, Jieutonne J; Levis, Robert J

    2015-03-17

    A fiber-based laser with a pulse duration of 435 fs and a wavelength of 1042 nm was used to vaporize biological macromolecules intact from the condensed phase into the gas phase for nanospray postionization and mass analysis. Laser vaporization of dried standard protein samples from a glass substrate by 10 Hz bursts of 20 pulses having 10 μs pulse separation and energy resulted in signal comparable to a metal substrate. The protein signal observed from an aqueous droplet on a glass substrate was negligible compared to either a droplet on metal or a thin film on glass. The mass spectra generated from dried and aqueous protein samples by the low-energy, fiber laser were similar to the results from high-energy (500 μJ), 45-fs, 800-nm Ti:sapphire-based femtosecond laser electrospray mass spectrometry (LEMS) experiments, suggesting that the fiber-based femtosecond laser desorption mechanism involves a nonresonant, multiphoton process, rather than thermal- or photoacoustic-induced desorption. Direct analysis of whole blood performed without any pretreatment resulted in features corresponding to hemoglobin subunit-heme complex ions. The observation of intact molecular ions with low charge states from protein, and the tentatively assigned hemoglobin α subunit-heme complex from blood suggests that fiber-based femtosecond laser vaporization is a "soft" desorption source at a laser intensity of 2.39 × 10(12) W/cm(2). The low-energy, turnkey fiber laser demonstrates the potential of a more robust and affordable laser for femtosecond laser vaporization to deliver biological macromolecules into the gas phase for mass analysis.

  13. Protein crystallization with microseed matrix screening: application to human germline antibody Fabs

    International Nuclear Information System (INIS)

    Obmolova, Galina; Malia, Thomas J.; Teplyakov, Alexey; Sweet, Raymond W.; Gilliland, Gary L.

    2014-01-01

    The power of microseed matrix screening is demonstrated in the crystallization of a panel of antibody Fab fragments. The crystallization of 16 human antibody Fab fragments constructed from all pairs of four different heavy chains and four different light chains was enabled by employing microseed matrix screening (MMS). In initial screening, diffraction-quality crystals were obtained for only three Fabs, while many Fabs produced hits that required optimization. Application of MMS, using the initial screens and/or refinement screens, resulted in diffraction-quality crystals of these Fabs. Five Fabs that failed to give hits in the initial screen were crystallized by cross-seeding MMS followed by MMS optimization. The crystallization protocols and strategies that resulted in structure determination of all 16 Fabs are presented. These results illustrate the power of MMS and provide a basis for developing future strategies for macromolecular crystallization

  14. Human serum albumin crystals and method of preparation

    Science.gov (United States)

    Carter, Daniel C. (Inventor)

    1989-01-01

    Human serum albumin (HSA) crystals are provided in the form of tetragonal plates having the space groups P42(sub 1)2, the crystals being grown to sizes in excess of 0.5 mm in two dimensions and a thickness of 0.1 mm. Growth of the crystals is carried out by a hanging drop method wherein a precipitant solution containing polyethylene glycol (PEG) and a phosphate buffer is mixed with an HSA solution, and a droplet of mixed solution is suspended over a well of precipitant solution. Crystals grow to the desired size in 3 to 7 days. Concentration of reagents, pH and other parameters are controlled within prescribed limits. The resulting crystals exhibit a size and quality such as to allow performance of x ray diffraction studies and enable the conduct of drug binding studies as well as genetic engineering studies.

  15. Thermal neutron detectors based on complex oxide crystals

    CERN Document Server

    Ryzhikov, V; Volkov, V; Chernikov, V; Zelenskaya, O

    2002-01-01

    The ways of improvement of spectrometric quality of CWO and GSO crystals have been investigated with the aim of their application in thermal neutron detectors based on radiation capture reactions. The efficiency of the neutron detection by these crystals was measured, and the obtained data were compared with the results for sup 6 LiI(Tl) crystals. It is shown that the use of complex oxide crystals and neutron-absorption filters for spectrometry of thermal and resonance neutrons could be a promising method in combination with computer data processing. Numerical calculations are reported for spectra of gamma-quanta due to radiation capture of the neutrons. To compensate for the gamma-background lines, we used a crystal pair of heavy complex oxides with different sensitivity to neutrons.

  16. Role of crystal orientation on chemical mechanical polishing of single crystal copper

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Aibin, E-mail: abzhu@mail.xjtu.edu.cn; He, Dayong; Luo, Wencheng; Liu, Yangyang

    2016-11-15

    Highlights: • The role of crystal orientation in cooper CMP by quasi-continuum was studied. • The atom displacement diagrams were obtained and analyzed. • The stress distribution diagrams and load-displacement curves were analyzed. • This research is helpful to revealing the material removal mechanism of CMP. - Abstract: The material removal mechanism of single crystal copper in chemical mechanical polishing (CMP) has not been intensively investigated. And the role of crystal orientation in CMP of single crystal cooper is not quite clear yet. Quasi-continuum method was adopted in this paper to simulate the process of nano-particles grinding on single crystal copper in CMP process. Three different crystal orientations, i.e. x[100]y[001], x[001]y[110] and x[–211]y[111], were chosen for analysis. The atom displacement diagrams, stress distribution diagrams and load-displacement curves were obtained. After analyzing the deformation mechanism, residual stress of the work piece material and cutting force, results showed that, the crystal orientation of work piece has great influence on the deformation characteristics and surface quality of work piece during polishing. In the A(001)[100] orientation, the residual stress distribution after polishing is deeper, and the stress is larger than that in the B(110)[001] and C(111)[–211] orientations. And the average tangential cutting force in the A(001)[100] orientation is much larger than those in the other two crystal orientation. This research is helpful to revealing the material removal mechanism of CMP process.

  17. Salvage and storage of infectious disease protein targets in the SSGCID high-throughput crystallization pathway using microfluidics

    International Nuclear Information System (INIS)

    Christensen, Jeff; Gerdts, Cory J.; Clifton, Mathew C.; Stewart, Lance

    2011-01-01

    SSGCID protein crystals were salvaged and stored using the MPCS Plug Maker and CrystalCards when high-throughput traditional sitting-drop vapor diffusion initially failed. The MPCS Plug Maker is a microcapillary-based protein-crystallization system for generating diffraction-ready crystals from nanovolumes of protein. Crystallization screening using the Plug Maker was used as a salvage pathway for proteins that failed to crystallize during the initial observation period using the traditional sitting-drop vapor-diffusion method. Furthermore, the CrystalCards used to store the crystallization experiments set up by the Plug Maker are shown be a viable container for long-term storage of protein crystals without a discernable loss of diffraction quality with time. Use of the Plug Maker with SSGCID proteins is demonstrated to be an effective crystal-salvage and storage method

  18. Applications of thin-film sandwich crystallization platforms

    Energy Technology Data Exchange (ETDEWEB)

    Axford, Danny, E-mail: danny.axford@diamond.ac.uk; Aller, Pierre; Sanchez-Weatherby, Juan; Sandy, James [Diamond Light Source, Harwell Oxford, Didcot OX11 0DE (United Kingdom)

    2016-03-24

    Crystallization via sandwiches of thin polymer films is presented and discussed. Examples are shown of protein crystallization in, and data collection from, solutions sandwiched between thin polymer films using vapour-diffusion and batch methods. The crystallization platform is optimal for both visualization and in situ data collection, with the need for traditional harvesting being eliminated. In wells constructed from the thinnest plastic and with a minimum of aqueous liquid, flash-cooling to 100 K is possible without significant ice formation and without any degradation in crystal quality. The approach is simple; it utilizes low-cost consumables but yields high-quality data with minimal sample intervention and, with the very low levels of background X-ray scatter that are observed, is optimal for microcrystals.

  19. A decade of crystallization drops: crystallization of the cbb3 cytochrome c oxidase from Pseudomonas stutzeri.

    Science.gov (United States)

    Buschmann, Sabine; Richers, Sebastian; Ermler, Ulrich; Michel, Hartmut

    2014-04-01

    The cbb3 cytochrome c oxidases are distant members of the superfamily of heme copper oxidases. These terminal oxidases couple O2 reduction with proton transport across the plasma membrane and, as a part of the respiratory chain, contribute to the generation of an electrochemical proton gradient. Compared with other structurally characterized members of the heme copper oxidases, the recently determined cbb3 oxidase structure at 3.2 Å resolution revealed significant differences in the electron supply system, the proton conducting pathways and the coupling of O2 reduction to proton translocation. In this paper, we present a detailed report on the key steps for structure determination. Improvement of the protein quality was achieved by optimization of the number of lipids attached to the protein as well as the separation of two cbb3 oxidase isoenzymes. The exchange of n-dodecyl-β-D-maltoside for a precisely defined mixture of two α-maltosides and decanoylsucrose as well as the choice of the crystallization method had a most profound impact on crystal quality. This report highlights problems frequently encountered in membrane protein crystallization and offers meaningful approaches to improve crystal quality. © 2014 The Protein Society.

  20. Direct imaging electron microscopy (EM) methods in modern structural biology: overview and comparison with X-ray crystallography and single-particle cryo-EM reconstruction in the studies of large macromolecules.

    Science.gov (United States)

    Miyaguchi, Katsuyuki

    2014-10-01

    Determining the structure of macromolecules is important for understanding their function. The fine structure of large macromolecules is currently studied primarily by X-ray crystallography and single-particle cryo-electron microscopy (EM) reconstruction. Before the development of these techniques, macromolecular structure was often examined by negative-staining, rotary-shadowing and freeze-etching EM, which are categorised here as 'direct imaging EM methods'. In this review, the results are summarised by each of the above techniques and compared with respect to four macromolecules: the ryanodine receptor, cadherin, rhodopsin and the ribosome-translocon complex (RTC). The results of structural analysis of the ryanodine receptor and cadherin are consistent between each technique. The results obtained for rhodopsin vary to some extent within each technique and between the different techniques. Finally, the results for RTC are inconsistent between direct imaging EM and other analytical techniques, especially with respect to the space within RTC, the reasons for which are discussed. Then, the role of direct imaging EM methods in modern structural biology is discussed. Direct imaging methods should support and verify the results obtained by other analytical methods capable of solving three-dimensional molecular architecture, and they should still be used as a primary tool for studying macromolecule structure in vivo. © 2014 Société Française des Microscopies and Société de Biologie Cellulaire de France. Published by John Wiley & Sons Ltd.

  1. The performance studies of DKDP crystals grown by a rapid horizontal growth method

    Science.gov (United States)

    Xie, Xiaoyi; Qi, Hongji; Wang, Bin; Wang, Hu; Chen, Duanyang; Shao, Jianda

    2018-04-01

    A deuterated potassium dihydrogen phosphate (DKDP) crystal with about 70% deuterium level was grown by a rapid horizontal growth method with independent design equipment, which includes a continuous filtration system. The cooling program during crystal growth was designed according to a self-developed software to catch the size of growing crystal in real time. The crystal structure, optical performance and laser induced damage threshold (LIDT) of this DKDP crystal were investigated in this paper. The deuterium concentration of the crystal was confirmed by the neutron diffraction technique, which was effective and available in determining a complete range of deuteration level. The dielectric property was measured to evaluate the perfection of the lattice. The transmittance and LIDT were carried out further to evaluate the optical and functional properties of this DKDP crystal grown in the rapid horizontal growth technique. All of the detailed characterization for DKDP figured out that the 70% deuterated KDP crystal grown in this way had relatively good qualities.

  2. Crystal growth of new charge-transfer salts based on π-conjugated donor molecules

    Energy Technology Data Exchange (ETDEWEB)

    Morherr, Antonia, E-mail: morherr@stud.uni-frankfurt.de [Physikalisches Institut, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany); Witt, Sebastian [Physikalisches Institut, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany); Chernenkaya, Alisa [Graduate School Materials Science in Mainz, 55128 Mainz (Germany); Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz (Germany); Bäcker, Jan-Peter [Physikalisches Institut, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany); Schönhense, Gerd [Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz (Germany); Bolte, Michael [Institut für anorganische Chemie, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany); Krellner, Cornelius [Physikalisches Institut, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany)

    2016-09-01

    New charge transfer crystals of π-conjugated, aromatic molecules (phenanthrene and picene) as donors were obtained by physical vapor transport. The melting behavior, optimization of crystal growth and the crystal structure are reported for charge transfer salts with (fluorinated) tetracyanoquinodimethane (TCNQ-F{sub x}, x=0, 2, 4), which was used as acceptor material. The crystal structures were determined by single-crystal X-ray diffraction. Growth conditions for different vapor pressures in closed ampules were applied and the effect of these starting conditions for crystal size and quality is reported. The process of charge transfer was investigated by geometrical analysis of the crystal structure and by infrared spectroscopy on single crystals. With these three different acceptor strengths and the two sets of donor materials, it is possible to investigate the distribution of the charge transfer systematically. This helps to understand the charge transfer process in this class of materials with π-conjugated donor molecules.

  3. Time crystals: a review

    Science.gov (United States)

    Sacha, Krzysztof; Zakrzewski, Jakub

    2018-01-01

    Time crystals are time-periodic self-organized structures postulated by Frank Wilczek in 2012. While the original concept was strongly criticized, it stimulated at the same time an intensive research leading to propositions and experimental verifications of discrete (or Floquet) time crystals—the structures that appear in the time domain due to spontaneous breaking of discrete time translation symmetry. The struggle to observe discrete time crystals is reviewed here together with propositions that generalize this concept introducing condensed matter like physics in the time domain. We shall also revisit the original Wilczek’s idea and review strategies aimed at spontaneous breaking of continuous time translation symmetry.

  4. Thermodynamics of Crystals

    Science.gov (United States)

    Navrotsky, Alexandra

    Thermodynamics of Crystals is a gold mine of a references bargain with more derivations of useful equations per dollar, or per page, than almost any other book I know. Useful to whom? To the solid state physicist, the solid state chemist working the geophysicist, the rock mechanic, the mineral physicist. Useful for what? For lattice dynamics, crystal potentials, band structure. For elegant, rigorous, and concise derivations of fundamental equations. For comparison of levels of approximation. For some data and physical insights, especially for metals and simple halides. This book is a reissue, with some changes and additions, of a 1970 treatise. It ages well, since the fundamentals do not change.

  5. Photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Sanchez Bjarklev, Araceli

    Photonic crystal fibres represent one of the most active research areas today in the field of optics. The diversity of applications that may be addressed by these fibres and their fundamental appeal, by opening up the possibility of guiding light in a radically new way compared to conventional...... optical fibres, have spun an interest from almost all areas of optics and photonics. The aim of this book is to provide an understanding of the different types of photonic crystal fibres and to outline some of the many new and exciting applications that these fibres offer. The book is intended for both...

  6. New developments in flexible cholesteric liquid crystal displays

    Science.gov (United States)

    Schneider, Tod; Davis, Donald J.; Franklin, Sean; Venkataraman, Nithya; McDaniel, Diaz; Nicholson, Forrest; Montbach, Erica; Khan, Asad; Doane, J. William

    2007-02-01

    Flexible Cholesteric liquid crystal displays have been rapidly maturing into a strong contender in the flexible display market. Encapsulation of the Cholesteric liquid crystal permits the use of flexible plastic substrates and roll-to-roll production. Recent advances include ultra-thin displays, laser-cut segmented displays of variable geometry, and smart card applications. Exciting technologies such as simultaneous laser-edge sealing and singulation enable high volume production, excellent quality control and non-traditional display geometries and formats.

  7. Crystal and molecular simulation of high-performance polymers.

    Science.gov (United States)

    Colquhoun, H M; Williams, D J

    2000-03-01

    Single-crystal X-ray analyses of oligomeric models for high-performance aromatic polymers, interfaced to computer-based molecular modeling and diffraction simulation, have enabled the determination of a range of previously unknown polymer crystal structures from X-ray powder data. Materials which have been successfully analyzed using this approach include aromatic polyesters, polyetherketones, polythioetherketones, polyphenylenes, and polycarboranes. Pure macrocyclic homologues of noncrystalline polyethersulfones afford high-quality single crystals-even at very large ring sizes-and have provided the first examples of a "protein crystallographic" approach to the structures of conventionally amorphous synthetic polymers.

  8. Heteroplasmon hybridization in stacked complementary plasmo-photonic crystals.

    Science.gov (United States)

    Iwanaga, Masanobu; Choi, Bongseok

    2015-03-11

    We constructed plasmo-photonic crystals in which efficient light-trapping, plasmonic resonances couple with photonic guided resonances of large density of states and high-quality factor. We have numerically and experimentally shown that heteroplasmon hybrid modes emerge in stacked complementary (SC) plasmo-photonic crystals. The resonant electromagnetic-field distributions evidence that the two hybrid modes originate from two different heteroplasmons, exhibiting a large energy splitting of 300 meV. We further revealed a series of plasmo-photonic modes in the SC crystals.

  9. Filtering of elastic waves by opal-based hypersonic crystal.

    Science.gov (United States)

    Salasyuk, Alexey S; Scherbakov, Alexey V; Yakovlev, Dmitri R; Akimov, Andrey V; Kaplyanskii, Alexander A; Kaplan, Saveliy F; Grudinkin, Sergey A; Nashchekin, Alexey V; Pevtsov, Alexander B; Golubev, Valery G; Berstermann, Thorsten; Brüggemann, Christian; Bombeck, Michael; Bayer, Manfred

    2010-04-14

    We report experiments in which high quality silica opal films are used as three-dimensional hypersonic crystals in the 10 GHz range. Controlled sintering of these structures leads to well-defined elastic bonding between the submicrometer-sized silica spheres, due to which a band structure for elastic waves is formed. The sonic crystal properties are studied by injection of a broadband elastic wave packet with a femtosecond laser. Depending on the elastic bonding strength, the band structure separates long-living surface acoustic waves with frequencies in the complete band gap from bulk waves with band frequencies that propagate into the crystal leading to a fast decay.

  10. Iron single crystal growth from a lithium-rich melt

    Science.gov (United States)

    Fix, M.; Schumann, H.; Jantz, S. G.; Breitner, F. A.; Leineweber, A.; Jesche, A.

    2018-03-01

    α -Fe single crystals of rhombic dodecahedral habit were grown from a Li84N12Fe∼3 melt. Crystals of several millimeter along a side form at temperatures around T ≈ 800 ° C. Upon further cooling the growth competes with the formation of Fe-doped Li3N. The b.c.c. structure and good sample quality of α -Fe single crystals were confirmed by X-ray and electron diffraction as well as magnetization measurements and chemical analysis. A nitrogen concentration of 90 ppm was detected by means of carrier gas hot extraction. Scanning electron microscopy did not reveal any sign of iron nitride precipitates.

  11. Acoustic transfer of protein crystals from agarose pedestals to micromeshes for high-throughput screening

    International Nuclear Information System (INIS)

    Cuttitta, Christina M.; Ericson, Daniel L.; Scalia, Alexander; Roessler, Christian G.; Teplitsky, Ella; Joshi, Karan; Campos, Olven; Agarwal, Rakhi; Allaire, Marc; Orville, Allen M.; Sweet, Robert M.; Soares, Alexei S.

    2015-01-01

    An acoustic high-throughput screening method is described for harvesting protein crystals and combining the protein crystals with chemicals such as a fragment library. Acoustic droplet ejection (ADE) is an emerging technology with broad applications in serial crystallography such as growing, improving and manipulating protein crystals. One application of this technology is to gently transfer crystals onto MiTeGen micromeshes with minimal solvent. Once mounted on a micromesh, each crystal can be combined with different chemicals such as crystal-improving additives or a fragment library. Acoustic crystal mounting is fast (2.33 transfers s −1 ) and all transfers occur in a sealed environment that is in vapor equilibrium with the mother liquor. Here, a system is presented to retain crystals near the ejection point and away from the inaccessible dead volume at the bottom of the well by placing the crystals on a concave agarose pedestal (CAP) with the same chemical composition as the crystal mother liquor. The bowl-shaped CAP is impenetrable to crystals. Consequently, gravity will gently move the crystals into the optimal location for acoustic ejection. It is demonstrated that an agarose pedestal of this type is compatible with most commercially available crystallization conditions and that protein crystals are readily transferred from the agarose pedestal onto micromeshes with no loss in diffraction quality. It is also shown that crystals can be grown directly on CAPs, which avoids the need to transfer the crystals from the hanging drop to a CAP. This technology has been used to combine thermolysin and lysozyme crystals with an assortment of anomalously scattering heavy atoms. The results point towards a fast nanolitre method for crystal mounting and high-throughput screening

  12. Acoustic transfer of protein crystals from agarose pedestals to micromeshes for high-throughput screening

    Energy Technology Data Exchange (ETDEWEB)

    Cuttitta, Christina M. [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); The City University of New York, 2800 Victory Boulevard, Staten Island, NY 10314 (United States); Ericson, Daniel L. [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); University at Buffalo, SUNY, 12 Capen Hall, Buffalo, NY 14260 (United States); Scalia, Alexander [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Binghamton University, 4400 Vestal Parkway East, Binghamton, NY 11973-5000 (United States); Roessler, Christian G. [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Teplitsky, Ella [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Stony Brook University, Stony Brook, NY 11794-5215 (United States); Joshi, Karan [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); PEC University of Technology, Chandigarh (India); Campos, Olven [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33414 (United States); Agarwal, Rakhi; Allaire, Marc [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Orville, Allen M. [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Sweet, Robert M.; Soares, Alexei S., E-mail: soares@bnl.gov [Brookhaven National Laboratory, Upton, NY 11973-5000 (United States)

    2015-01-01

    An acoustic high-throughput screening method is described for harvesting protein crystals and combining the protein crystals with chemicals such as a fragment library. Acoustic droplet ejection (ADE) is an emerging technology with broad applications in serial crystallography such as growing, improving and manipulating protein crystals. One application of this technology is to gently transfer crystals onto MiTeGen micromeshes with minimal solvent. Once mounted on a micromesh, each crystal can be combined with different chemicals such as crystal-improving additives or a fragment library. Acoustic crystal mounting is fast (2.33 transfers s{sup −1}) and all transfers occur in a sealed environment that is in vapor equilibrium with the mother liquor. Here, a system is presented to retain crystals near the ejection point and away from the inaccessible dead volume at the bottom of the well by placing the crystals on a concave agarose pedestal (CAP) with the same chemical composition as the crystal mother liquor. The bowl-shaped CAP is impenetrable to crystals. Consequently, gravity will gently move the crystals into the optimal location for acoustic ejection. It is demonstrated that an agarose pedestal of this type is compatible with most commercially available crystallization conditions and that protein crystals are readily transferred from the agarose pedestal onto micromeshes with no loss in diffraction quality. It is also shown that crystals can be grown directly on CAPs, which avoids the need to transfer the crystals from the hanging drop to a CAP. This technology has been used to combine thermolysin and lysozyme crystals with an assortment of anomalously scattering heavy atoms. The results point towards a fast nanolitre method for crystal mounting and high-throughput screening.

  13. The Crystal Hotel: A Microfluidic Approach to Biomimetic Crystallization.

    Science.gov (United States)

    Gong, Xiuqing; Wang, Yun-Wei; Ihli, Johannes; Kim, Yi-Yeoun; Li, Shunbo; Walshaw, Richard; Chen, Li; Meldrum, Fiona C

    2015-12-02

    A "crystal hotel" microfluidic device that allows crystal growth in confined volumes to be studied in situ is used to produce large calcite single crystals with predefined crystallographic orientation, microstructure, and shape by control of the detailed physical environment, flow, and surface chemistry. This general approach can be extended to form technologically important, nanopatterned single crystals. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Oscillations of the crystal-melt interface caused by harmonic oscillations of the pulling rate for the cylindrical phase of crystal growth

    Science.gov (United States)

    Vasil'ev, M. G.

    2017-02-01

    A technique for measuring the crystal cross-sectional area with a weight sensor based on the difference between its readings at the extreme rod positions in the stepwise and continuous modes of modulation of the pulling rate is proposed for the low-thermal gradient Czochralski method. A change in the crystallization rate at harmonic oscillations of the pulling rate is estimated with the aim of conserving the quality of the growing crystal for this measurement method.

  15. Space growth studies of Ce-doped Bi12SiO20 single crystal

    International Nuclear Information System (INIS)

    Zhou, Y.F.; Wang, J.C.; Tang, L.A.; Pan, Z.L.; Chen, N.F.; Chen, W.C.; Huang, Y.Y.; He, W.

    2004-01-01

    Ce-doped Bi 12 SiO 20 (BSO) single crystal was grown on board of the Chinese Spacecraft-Shenzhou No. 3. A cylindrical crystal, 10 mm in diameter and 40 mm in length, was obtained. The morphology of crystals is significantly different for ground- and space-grown portions. The space- and ground-grown crystals have been characterized by Ce concentration distribution, X-ray rocking curve absorption spectrum and micro-Raman spectrum. The results show that the quality of Ce-doped BSO crystal grown in space is more homogeneous and more perfect than that of ground grown one

  16. Light-Induced Tellurium Enrichment on CdZnTe Crystal Surfaces Detected by Raman Spectroscopy

    International Nuclear Information System (INIS)

    Hawkins, Samantha A.; Villa-Aleman, Eliel; Duff, Martine C.; Hunter, Doug B.; Burger, Arnold; Groza, Michael; Buliga, Vladimir; Black, David R.

    2008-01-01

    CdZnTe (CZT) crystals can be grown under controlled conditions to produce high-quality crystals to be used as room-temperature radiation detectors. Even the best crystal growth methods result in defects, such as tellurium secondary phases, that affect the crystal's performance. In this study, CZT crystals were analyzed by micro-Raman spectroscopy. The growth of Te rich areas on the surface was induced by low-power lasers. The growth was observed versus time with low-power Raman scattering and was observed immediately under higher-power conditions. The detector response was also measured after induced Te enrichment.

  17. LIGHT INDUCED TELLURIUM ENRICHMENT ON CDZNTE CRYSTAL SURFACES DETECTED BY RAMAN SPECTROSCOPY

    International Nuclear Information System (INIS)

    Hawkins, S; Eliel Villa-Aleman, E; Martine Duff, M; Douglas Hunter, D

    2007-01-01

    Synthetic CdZnTe or 'CZT' crystals can be grown under controlled conditions to produce high quality crystals to be used as room temperature radiation detectors. Even the best crystal growth methods result in defects, such as tellurium secondary phases, that affect the crystal's performance. In this study, CZT crystals were analyzed by micro Raman spectroscopy. The growth of Te rich areas on the surface was induced by low powered lasers. The growth was observed versus time with low power Raman scattering and was observed immediately under higher power conditions. The detector response was also measured after induced Te enrichment

  18. Hydrothermally grown zeolite crystals

    International Nuclear Information System (INIS)

    Durrani, S.K.; Qureshi, A.H.; Hussain, M.A.; Qazi, N.K.

    2009-01-01

    The aluminium-deficient and ferrosilicate zeolite-type materials were synthesized by hydrothermal process at 150-170 degree C for various periods of time from the mixtures containing colloidal reactive silica, sodium aluminate, sodium hydroxide, iron nitrate and organic templates. Organic polycation templates were used as zeolite crystal shape modifiers to enhance relative growth rates. The template was almost completely removed from the zeolite specimens by calcination at 550 degree C for 8h in air. Simultaneous thermogravimetric (TG) and differential thermal analysis (DTA) was performed to study the removal of water molecules and the amount of organic template cations occluded inside the crystal pore of zeolite framework. The 12-13% weight loss in the range of (140-560 degree C) was associated with removal of the (C/sub 3/H/sub 7/)/sub 4/ N+ cation and water molecules. X-ray diffraction (XRD) analysis and scanning electron microscope (SEM) techniques were employed to study the structure, morphology and surface features of hydrothermally grown aluminium-deficient and ferrosilicate zeolite-type crystals. In order to elucidate the mode of zeolite crystallization the crystallinity and unit cell parameters of the materials were determined by XRD, which are the function of Al and Fe contents of zeolites. (author)

  19. Poet Lake Crystal Approval

    Science.gov (United States)

    This September 19, 2016 letter from EPA approves the petition from Poet Biorefining-Lake Crystal, regarding non-grandfathered ethanol produced through a dry mill process, qualifying under the Clean Air Act for renewable fuel (D-code 6) RINs under the RFS

  20. Liquid crystal display

    International Nuclear Information System (INIS)

    Takami, K.

    1981-01-01

    An improved liquid crystal display device is described which can display letters, numerals and other necessary patterns in the night time using a minimized amount of radioactive material. To achieve this a self-luminous light source is placed in a limited region corresponding to a specific display area. (U.K.)

  1. Soap Bubbles and Crystals

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 6. Soap Bubbles and Crystals. Jean E Taylor. General Article Volume 11 Issue 6 June 2006 pp 26-30. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/011/06/0026-0030. Keywords. Soap bubble ...

  2. Agile Photonic Crystals

    Science.gov (United States)

    2011-01-03

    75, pp. 3253-3256, Oct. 1995. [24] F. Benabid, J. C. Knight, and P. S. J. Russell, “Particle levitation and guidance in hollow-core photonic crystal...B. Mizaikoff, “Midinfrared sensors meet nanotechnology: Trace gas sensing with quantum cascade lasers inside photonic band-gap hollow waveguides

  3. The Crystal Set

    Science.gov (United States)

    Greenslade, Thomas B., Jr.

    2014-01-01

    In past issues of this journal, the late H. R. Crane wrote a long series of articles under the running title of "How Things Work." In them, Dick dealt with many questions that physics teachers asked themselves, but did not have the time to answer. This article is my attempt to work through the physics of the crystal set, which I thought…

  4. WORKSHOP: Scintillating crystals

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1992-12-15

    Scintillating crystals are one of the big spinoff success stories of particle physics, and from 22-26 September an international workshop in Chamonix in the French Alps looked at the increasing role of these materials in pure and applied science and in industry.

  5. The CMS crystal calorimeter

    CERN Document Server

    Lustermann, W

    2004-01-01

    The measurement of the energy of electrons and photons with very high accuracy is of primary importance far the study of many physics processes at the Large Hadron Collider (LHC), in particular for the search of the Higgs Boson. The CMS experiment will use a crystal calorimeter with pointing geometry, almost covering 4p, as it offers a very good energy resolution. It is divided into a barrel composed of 61200 lead tungstate crystals, two end-caps with 14648 crystals and a pre-shower detector in front of the end-cap. The challenges of the calorimeter design arise from the high radiation environment, the 4 Tesla magnetic eld, the high bunch crossing rate of 40 MHz and the large dynamic range, requiring the development of fast, radiation hard crystals, photo-detectors and readout electronics. An overview of the construction and design of the calorimeter will be presented, with emphasis on some of the details required to meet the demanding performance goals. 19 Refs.

  6. Positrons in ionic crystals

    International Nuclear Information System (INIS)

    Pareja, R.

    1988-01-01

    Positron annihilation experiments in ionic crystals are reviewed and their results are arranged. A discussion about the positron states in these materials is made in the light of these results and the different proposed models. The positronium in alkali halides is specially considered. (Author)

  7. WORKSHOP: Scintillating crystals

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    Scintillating crystals are one of the big spinoff success stories of particle physics, and from 22-26 September an international workshop in Chamonix in the French Alps looked at the increasing role of these materials in pure and applied science and in industry

  8. Thermoelectricity in liquid crystals

    Science.gov (United States)

    Mohd Said, Suhana; Nordin, Abdul Rahman; Abdullah, Norbani; Balamurugan, S.

    2015-09-01

    The thermoelectric effect, also known as the Seebeck effect, describes the conversion of a temperature gradient into electricity. A Figure of Merit (ZT) is used to describe the thermoelectric ability of a material. It is directly dependent on its Seebeck coefficient and electrical conductivity, and inversely dependent on its thermal conductivity. There is usually a compromise between these parameters, which limit the performance of thermoelectric materials. The current achievement for ZT~2.2 falls short of the expected threshold of ZT=3 to allow its viability in commercial applications. In recent times, advances in organic thermoelectrics been significant, improving by over 3 orders of magnitude over a period of about 10 years. Liquid crystals are newly investigated as candidate thermoelectric materials, given their low thermal conductivity, inherent ordering, and in some cases, reasonable electrical conductivity. In this work the thermoelectric behaviour of a discotic liquid crystal, is discussed. The DLC was filled into cells coated with a charge injector, and an alignment of the columnar axis perpendicular to the substrate was allowed to form. This thermoelectric behavior can be correlated to the order-disorder transition. A reasonable thermoelectric power in the liquid crystal temperature regime was noted. In summary, thermoelectric liquid crystals may have the potential to be utilised in flexible devices, as a standalone power source.

  9. Chemistry of microporous crystals

    International Nuclear Information System (INIS)

    Inui, Tomoyuki; Namba, Seitaro; Tatsumi, Takashi

    1991-01-01

    This volume contains three papers which are in INIS scope, entitled respectively: 129 Xe-NMR study of the crystallization of SAPO-37, NMR studies of cation localization in zeolites, developments in x-ray and neutron diffraction methods for zeolites. (H.W.). refs.; figs.; tabs

  10. Electrical properties of molecular crystals

    International Nuclear Information System (INIS)

    Barraud, A.

    1968-01-01

    This literature survey summarizes the electrical properties of molecular crystals: molecular crystal structure, transport and excitation mechanisms of charge-carriers, and differences compared to inorganic semi-conductors. The main results concerning the electrical conductivity of the most-studied molecular crystals are presented, together with the optical and photo-electrical properties of these crystals. Finally the different types of electrical measurements used are reviewed, as well as the limits of each method. (author) [fr

  11. Surface Restructuring of Hybrid Perovskite Crystals

    KAUST Repository

    Banavoth, Murali

    2016-11-07

    Hybrid perovskite crystals have emerged as an important class of semiconductors because of their remarkable performance in optoelectronics devices. The interface structure and chemistry of these crystals are key determinants of the device\\'s performance. Unfortunately, little is known about the intrinsic properties of the surfaces of perovskite materials because extrinsic effects, such as complex microstructures, processing conditions, and hydration under ambient conditions, are thought to cause resistive losses and high leakage current in solar cells. We reveal the intrinsic structural and optoelectronic properties of both pristinely cleaved and aged surfaces of single crystals. We identify surface restructuring on the aged surfaces (visualized on the atomic-scale by scanning tunneling microscopy) that lead to compositional and optical bandgap changes as well as degradation of carrier dynamics, photocurrent, and solar cell device performance. The insights reported herein clarify the key variables involved in the performance of perovskite-based solar cells and fabrication of high-quality surface single crystals, thus paving the way toward their future exploitation in highly efficient solar cells.

  12. Optimization of photonic crystal cavities

    DEFF Research Database (Denmark)

    Wang, Fengwen; Sigmund, Ole

    2017-01-01

    We present optimization of photonic crystal cavities. The optimization problem is formulated to maximize the Purcell factor of a photonic crystal cavity. Both topology optimization and air-hole-based shape optimization are utilized for the design process. Numerical results demonstrate...... that the Purcell factor of the photonic crystal cavity can be significantly improved through optimization....

  13. UV detectors based on epitaxial diamond films grown on single-crystal diamond substrates by vapor-phase synthesis

    International Nuclear Information System (INIS)

    Sharonov, G.V.; Petrov, S.A.; Bol'shakov, A.P.; Ral'chenko, V.G.; Kazyuchits, N.M.

    2010-01-01

    The prospects for use of CVD-technology for epitaxial growth of single-crystal diamond films of instrumental quality in UHF plasma for the production of optoelectronic devices are discussed. A technology for processing diamond single crystals that provides a perfect surface crystal structure with roughness less than 0,5 nm was developed. It was demonstrated that selective UV detectors based on synthetic single-crystal diamond substrates coated with single-crystal films can be produced. A criterion for selecting clean and structurally perfect single crystals of synthetic diamond was developed for the epitaxial growth technology. (authors)

  14. Calculation of site affinity constants and cooperativity coefficients for binding of ligands and/or protons to macromolecules. II. Relationships between chemical model and partition function algorithm.

    Science.gov (United States)

    Fisicaro, E; Braibanti, A; Lamb, J D; Oscarson, J L

    1990-05-01

    macromolecule or receptor M with four classes of sites; and (4) the binding to a macromolecule M of ligand A which is in turn a receptor for proton H. With reference to a specific example, it is shown how a computer program for least-squares refinement of variables kappa j and bj can be organized. The chemical model from the free components M, A, and H to the saturated macrospecies MpAQHR, with possible complex macrospecies MpAq and AHR, is defined first.(ABSTRACT TRUNCATED AT 250 WORDS)

  15. Graphene-based photonic crystal

    International Nuclear Information System (INIS)

    Berman, Oleg L.; Boyko, Vladimir S.; Kezerashvili, Roman Ya.; Kolesnikov, Anton A.; Lozovik, Yurii E.

    2010-01-01

    A novel type of photonic crystal formed by embedding a periodic array of constituent stacks of alternating graphene and dielectric discs into a background dielectric medium is proposed. The photonic band structure and transmittance of such photonic crystal are calculated. The graphene-based photonic crystals can be used effectively as the frequency filters and waveguides for the far infrared region of electromagnetic spectrum. Due to substantial suppression of absorption of low-frequency radiation in doped graphene the damping and skin effect in the photonic crystal are also suppressed. The advantages of the graphene-based photonic crystal are discussed.

  16. Automation and remote access of EMBL small angle X-ray scattering beamline X33 dedicated to biological macromolecules

    International Nuclear Information System (INIS)

    Weifeng Shang; Roessle, M.; Blanchet, C.; Zozulya, A.; Franke, D.; Petoukhov, M.; Kikhney, A.; Svergun, D.

    2009-01-01

    Full text: The small-angle X-ray scattering beamline X33 of the European Molecular Biology Laboratory (EMBL) at the DORIS III storage ring (HASYLAB/DESY) has been dedicated to structural studies of non-crystalline biological systems for more than two decades. In the last several years, the introduction of new optical systems (monochromator, mirror, slits etc) and detector systems (large area image plate Mar345 and PILATUS 1M) leads to an improvement of photon flux by a factor of 3 and a reduction of the exposure time by a factor of 7. Moreover, an automated sample changer has been constructed and in operation since August 2007. The data analysis pipeline consisting of the program suite yields the radius of gyration and forward scattering intensity using Guinier analysis (AutoRg), pair distance distribution function p(r) using indirect Fourier transform method (AutoGNOM), and bead models using ab initio shape determination (DAMMIN and DAMMIF). The results of these analysis which are immediately available after each measurement provides an invaluable tool for data quality control during the data collection. Furthermore, works on remote control of the integrated data collection and analysis software is ongoing and expected to be operated in late 2009 where users can send their samples and control the measurements at home institutes. (author)

  17. Liquid crystals in tribology.

    Science.gov (United States)

    Carrión, Francisco-José; Martínez-Nicolás, Ginés; Iglesias, Patricia; Sanes, José; Bermúdez, María-Dolores

    2009-09-18

    Two decades ago, the literature dealing with the possible applications of low molar mass liquid crystals, also called monomer liquid crystals (MLCs), only included about 50 references. Today, thousands of papers, conference reports, books or book chapters and patents refer to the study and applications of MLCs as lubricants and lubricant additives and efforts are made to develop new commercial applications. The development of more efficient lubricants is of paramount technological and economic relevance as it is estimated that half the energy consumption is dissipated as friction. MLCs have shown their ability to form ordered boundary layers with good load-carrying capacity and to lower the friction coefficients, wear rates and contact temperature of sliding surfaces, thus contributing to increase the components service life and to save energy. This review includes the use of MLCs in lubrication, and dispersions of MLCs in conventional polymers (PDMLCs). Finally, new lubricating system composed of MLC blends with surfactants, ionic liquids or nanophases are considered.

  18. Liquid crystal dimers

    CERN Document Server

    Kumar Pal, Santanu

    2017-01-01

    This book covers in-depth discussion of design principles, synthesis and thermal behavior of all types of liquid crystal (LC) dimers. The text presents recent advances in the field of LC dimers consisting of different mesogenic units such as calamitic, discotic and bent-core molecules. It starts with a chapter on the introduction of liquid crystal dimers, including their odd-even behavior, basic classification of dimers and common mesophases in dimers. The text shows how the molecular architectures are being used to develop new materials to study a range of interesting phenomena such as the biaxial nematic phase containing rod-like and disc-like mesogenic units. Finally, the text presents perspectives related to technological relevance of these dimers such as dopants in LC display mixtures exhibiting faster relaxation time, strong flexoelectric coupling and others to effect control over the properties of these materials.

  19. Nonlinear Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Hansen, Kim Per

    2004-01-01

    Despite the general recession in the global economy and the collapse of the optical telecommunication market, research within specialty fibers is thriving. This is, more than anything else, due to the technology transition from standard all-glass fibers to photonic crystal fibers, which, instead....... The freedom to design the dispersion profile of the fibers is much larger and it is possible to create fibers, which support only a single spatial mode, regardless of wavelength. In comparison, the standard dispersion-shifted fibers are limited by a much lower index-contrast between the core and the cladding...... in 1996, and are today on their way to become the dominating technology within the specialty fiber field. Whether they will replace the standard fiber in the more traditional areas like telecommunication transmission, is not yet clear, but the nonlinear photonic crystal fibers are here to stay....

  20. Liquid crystal colloids

    CERN Document Server

    Muševič, Igor

    2017-01-01

    This book brings together the many concepts and discoveries in liquid crystal colloids contributed over the last twenty years and scattered across numerous articles and book chapters. It provides both a historical overview of the development of the field and a clear perspective on the future applications in photonics. The book covers all phenomena observed in liquid crystal colloids with an emphasis on experimental tools and applications of topology in condensed matter, as well as practical micro-photonics applications. It includes a number of spectacular manifestations of new topological phenomena not found or difficult to observe in other systems. Starting from the early works on nematic colloids, it explains the basics of topological defects in ordered media, charge and winding, and the elastic forces between colloidal particles in nematics. Following a detailed description of experimental methods, such as optical tweezing and particle tracking, the book eases the reader into the theoretical part, which de...

  1. Dosimetry for Crystals Irradiation

    CERN Document Server

    Lecomte, Pierre

    2005-01-01

    Before shipment to CMS, all PbWO4 crystals produced in China are irradiated there with 60 Co , in order to insure that the induced absorption coefficient is within specifications. Acceptance tests at CERNand at ENEA also include irradiation with gamma rays from 60 Co sources. There were initially discrepancies in quoted doses and doserates as well as in induced absorption coefficients. The present work resolves the discrepancies in irradiation measurements and defines common dosimetry methods for consistency checks between irradiation facilities.

  2. Crystals against cancer

    CERN Multimedia

    2009-01-01

    This is a remarkable example of direct technology transfer from particle physics to medicine. Clinical trials have begun in Portugal on a new medical imaging system for the diagnosis of breast cancer, which uses positron emission tomography (PET). The system, developed by a Portuguese consortium in collaboration with CERN and laboratories participating in the Crystal Clear collaboration, will detect even the smallest tumours and thus help avoid unnecessary biopsies.

  3. On crystallization of law

    Directory of Open Access Journals (Sweden)

    Szmodis Jenő

    2014-01-01

    Full Text Available The article introduces the problem of autonomy of law. The paper examines the medieval origins of legal positivism from a historical approach, sketching the main theories concerning the emergence of law, and phrasing some preliminary consideration for a historical and philosophical view of the problem of the birth of law. As a result of reasoning the article suggests some legal historical and human ethological ideas relating to the phenomena of crystallization of the law.

  4. Phononic crystals fundamentals and applications

    CERN Document Server

    Adibi, Ali

    2016-01-01

    This book provides an in-depth analysis as well as an overview of phononic crystals. This book discusses numerous techniques for the analysis of phononic crystals and covers, among other material, sonic and ultrasonic structures, hypersonic planar structures and their characterization, and novel applications of phononic crystals. This is an ideal book for those working with micro and nanotechnology, MEMS (microelectromechanical systems), and acoustic devices. This book also: Presents an introduction to the fundamentals and properties of phononic crystals Covers simulation techniques for the analysis of phononic crystals Discusses sonic and ultrasonic, hypersonic and planar, and three-dimensional phononic crystal structures Illustrates how phononic crystal structures are being deployed in communication systems and sensing systems.

  5. Quartz crystal fabrication facility

    Science.gov (United States)

    Ney, R. J.

    1980-05-01

    The report describes the design and operation of a five chamber, interconnected vacuum system, which is capable of cleaning, plating, and sealing precision quartz crystal units in ceramic flatpack enclosures continuously in a high vacuum environment. The production rate design goal was 200 units per eight hour day. A unique nozzle beam gold deposition source was developed to operate for extended periods of time without reloading. The source puts out a narrow beam of gold typically in the order of 2 1/2 deg included cone angle. Maximum deposition rates are in the order of 400 a/min at 5.5 in. 'throw' distance used. Entrance and exit air lock chambers expedite the material throughput, so that the processing chambers are at high vacuum for extended periods of time. A stainless steel conveyor belt, in conjunction with three vacuum manipulators, transport the resonator components to the various work stations. Individual chambers are normally separated from each other by gate valves. The crystal resonators, mounted in flatpack frames but unplated, are loaded into transport trays in a lid-frame-lid sequency for insertion into the system and exit as completed crystal units. The system utilizes molybdenum coated ball bearings at essentially all friction surfaces. The gold sources and plating mask heads are equipped with elevators and gate valves, so that they can be removed from the system for maintenance without exposing the chambers to atmosphere.

  6. Slotted Photonic Crystal Sensors

    Science.gov (United States)

    Scullion, Mark G.; Krauss, Thomas F.; Di Falco, Andrea

    2013-01-01

    Optical biosensors are increasingly being considered for lab-on-a-chip applications due to their benefits such as small size, biocompatibility, passive behaviour and lack of the need for fluorescent labels. The light guiding mechanisms used by many of them results in poor overlap of the optical field with the target molecules, reducing the maximum sensitivity achievable. This review article presents a new platform for optical biosensors, namely slotted photonic crystals, which provide higher sensitivities due to their ability to confine, spatially and temporally, the optical mode peak within the analyte itself. Loss measurements showed values comparable to standard photonic crystals, confirming their ability to be used in real devices. A novel resonant coupler was designed, simulated, and experimentally tested, and was found to perform better than other solutions within the literature. Combining with cavities, microfluidics and biological functionalization allowed proof-of-principle demonstrations of protein binding to be carried out. Higher sensitivities were observed in smaller structures than possible with most competing devices reported in the literature. This body of work presents slotted photonic crystals as a realistic platform for complete on-chip biosensing; addressing key design, performance and application issues, whilst also opening up exciting new ideas for future study. PMID:23503295

  7. Slotted Photonic Crystal Sensors

    Directory of Open Access Journals (Sweden)

    Andrea Di Falco

    2013-03-01

    Full Text Available Optical biosensors are increasingly being considered for lab-on-a-chip applications due to their benefits such as small size, biocompatibility, passive behaviour and lack of the need for fluorescent labels. The light guiding mechanisms used by many of them results in poor overlap of the optical field with the target molecules, reducing the maximum sensitivity achievable. This review article presents a new platform for optical biosensors, namely slotted photonic crystals, which provide higher sensitivities due to their ability to confine, spatially and temporally, the optical mode peak within the analyte itself. Loss measurements showed values comparable to standard photonic crystals, confirming their ability to be used in real devices. A novel resonant coupler was designed, simulated, and experimentally tested, and was found to perform better than other solutions within the literature. Combining with cavities, microfluidics and biological functionalization allowed proof-of-principle demonstrations of protein binding to be carried out. Higher sensitivities were observed in smaller structures than possible with most competing devices reported in the literature. This body of work presents slotted photonic crystals as a realistic platform for complete on-chip biosensing; addressing key design, performance and application issues, whilst also opening up exciting new ideas for future study.

  8. Single-Crystal Diamond Nanobeam Waveguide Optomechanics

    Science.gov (United States)

    Khanaliloo, Behzad; Jayakumar, Harishankar; Hryciw, Aaron C.; Lake, David P.; Kaviani, Hamidreza; Barclay, Paul E.

    2015-10-01

    Single-crystal diamond optomechanical devices have the potential to enable fundamental studies and technologies coupling mechanical vibrations to both light and electronic quantum systems. Here, we demonstrate a single-crystal diamond optomechanical system and show that it allows excitation of diamond mechanical resonances into self-oscillations with amplitude >200 nm . The resulting internal stress field is predicted to allow driving of electron spin transitions of diamond nitrogen-vacancy centers. The mechanical resonances have a quality factor >7 ×105 and can be tuned via nonlinear frequency renormalization, while the optomechanical interface has a 150 nm bandwidth and 9.5 fm /√{Hz } sensitivity. In combination, these features make this system a promising platform for interfacing light, nanomechanics, and electron spins.

  9. Single-Crystal Diamond Nanobeam Waveguide Optomechanics

    Directory of Open Access Journals (Sweden)

    Behzad Khanaliloo

    2015-12-01

    Full Text Available Single-crystal diamond optomechanical devices have the potential to enable fundamental studies and technologies coupling mechanical vibrations to both light and electronic quantum systems. Here, we demonstrate a single-crystal diamond optomechanical system and show that it allows excitation of diamond mechanical resonances into self-oscillations with amplitude >200  nm. The resulting internal stress field is predicted to allow driving of electron spin transitions of diamond nitrogen-vacancy centers. The mechanical resonances have a quality factor >7×10^{5} and can be tuned via nonlinear frequency renormalization, while the optomechanical interface has a 150 nm bandwidth and 9.5  fm/sqrt[Hz] sensitivity. In combination, these features make this system a promising platform for interfacing light, nanomechanics, and electron spins.

  10. On dewetting of thin films due to crystallization (crystallization dewetting).

    Science.gov (United States)

    Habibi, Mehran; Rahimzadeh, Amin; Eslamian, Morteza

    2016-03-01

    Drying and crystallization of a thin liquid film of an ionic or a similar solution can cause dewetting in the resulting thin solid film. This paper aims at investigating this type of dewetting, herein termed "crystallization dewetting", using PbI2 dissolved in organic solvents as the model solution. PbI2 solid films are usually used in X-ray detection and lead halide perovskite solar cells. In this work, PbI2 films are fabricated using spin coating and the effect of major parameters influencing the crystallization dewetting, including the type of the solvent, solution concentration, drying temperature, spin speed, as well as imposed vibration on the substrate are studied on dewetting, surface profile and coverage, using confocal scanning laser microscopy. Simplified hydrodynamic governing equations of crystallization in thin films are presented and using a mathematical representation of the process, it is phenomenologically demonstrated that crystallization dewetting occurs due to the absorption and consumption of the solution surrounding a growing crystal. Among the results, it is found that a low spin speed (high thickness), a high solution concentration and a low drying temperature promote crystal growth, and therefore crystallization dewetting. It is also shown that imposed vibration on the substrate can affect the crystal size and crystallization dewetting.

  11. Simulation Studies of LCST-like Phase Transitions in Elastin-like Polypeptides (ELPs) and Conjugates of ELP with Rigid Macromolecules

    Science.gov (United States)

    Condon, Joshua; Martin, Tyler; Jayaraman, Arthi

    We use atomistic (AA) and coarse-grained (CG) molecular dynamics simulations to elucidate the thermodynamic driving forces governing lower critical solution temperature (LCST)-like phase transition exhibited by elastin-like peptides (ELPs) and conjugates of ELP with other macromolecules. In the AA simulations, we study ELP oligomers in explicit water, and mark the transition as the temperature at which they undergo a change in ``hydration'' state. While AA simulations are restricted to small systems of short ELPs and do not capture the chain aggregation observed in experiments of ELPs, they guide the phenomenological CG model development by highlighting the solvent induced polymer-polymer effective interactions with changing temperature. In the CG simulations, we capture the LCST polymer aggregation by increasing polymer-polymer effective attractive interactions in an implicit solvent. We examine the impact of conjugating a block of LCST polymer to another rigid unresponsive macromolecular block on the LCST-like transition. We find that when multiple LCST polymers are conjugated to a rigid polymer block, increased crowding of the LCST polymers shifts the onset of chain aggregation to smaller effective polymer-polymer attraction compared to the free LCST polymers. These simulation results provide guidance on the design of conjugated bio-mimetic thermoresponsive materials, and shape the fundamental understanding of the impact of polymer crowding on phase behavior in thermoresponsive LCST polymer systems.

  12. 18FFPyKYNE, a fluoro-pyridine-based alkyne reagent designed for the fluorine-18 labelling of macromolecules using click chemistry

    International Nuclear Information System (INIS)

    Kuhnast, B.; Hinnen, F.; Tavitian, B.; Dolle, F.; Tavitian, B.

    2008-01-01

    [ 18 F]FPyKYNE (2-fluoro-3-pent-4-yn-1-yloxy-pyridine) is a novel fluoro-pyridine-based structure, designed for the fluorine-18 labelling of macromolecules using copper-catalysed Huisgen 1,3-dipolar cycloaddition (click chemistry). FPyKYNE (non-labelled as reference), as well as the 2-bromo, 2-nitro and 2-trimethylammonium analogues (as precursors for labelling with fluorine-18), was synthesized in 44, 95, 60 and 41%, respectively, from commercially available 5-chloro-pent-1-yne and the appropriate 2-substituted-3-hydroxypyridines. [ 18 F]FPyKYNE was synthesized in one single radiochemical step by reaction of no-carrier-added K[ 18 F]F-Kryptofix 222 (DMSO, 165 degrees C, 3-5 min) followed by C-18 SepPak cartridge pre-purification and finally semi-preparative HPLC purification on a Hewlett Packard SiO 2 Zorbax (R) Rx-SIL. Using the 2-nitropyridine or the pyridin-2-yl-trimethylammonium trifluoro-methanesulphonate precursor for labelling (30 and 10 μ mol, respectively), incorporation yields up to 90% were observed and 7.0-8.9 GBq (190-240 mCi) of [F-18]FPyKYNE ([ 18 F]-1) could be isolated within 60-70 min (HPLC purification included), starting from a 37.0 GBq (1.0 Ci) [ 18 F]fluoride batch (overall decay-corrected and isolated yields: 30-35%). (authors)

  13. Spectrum of hydrodynamic volumes and sizes of macromolecules of linear polyelectrolytes versus their charge density in salt-free aqueous solutions.

    Science.gov (United States)

    Pavlov, Georges M; Dommes, Olga A; Okatova, Olga V; Gavrilova, Irina I; Panarin, Evgenii F

    2018-04-18

    Molecular characteristics of statistical copolymers based on hydrophilic poly(N-methyl-N-vinylacetamide) have been monitored throughout the entire possible range of charge density from 1.5 to 39 mol%. Different trends in the dependence of intrinsic viscosity on the average charge density of polymer chains at minimal ionic strength were revealed. A new parameter, lqq/Abare, describing this behavior was proposed (lqq is the average distance between the neighboring charges along the chain, and Abare is the statistical segment length of a non-charged homologue). For polyelectrolyte chains, this parameter allows the regions of charge density values where electrostatic long-range or short-range interactions dominate to be indicated. Two homologous series of copolymers were characterized by methods of molecular hydrodynamics under conditions of suppressed charge effects. Intrinsic viscosity in salt-free solutions characterizing an individual macromolecule was estimated by a method proposed earlier [Pavlov et al., Russ. J. Appl. Chem., 2006, 79, 1407-1412].

  14. Is the Fractional Laser Still Effective in Assisting Cutaneous Macromolecule Delivery in Barrier-Deficient Skin? Psoriasis and Atopic Dermatitis as the Disease Models.

    Science.gov (United States)

    Lee, Woan-Ruoh; Shen, Shing-Chuan; Sung, Calvin T; Liu, Pei-Ying; Fang, Jia-You

    2018-04-26

    Most of the investigations into laser-assisted skin permeation have used the intact skin as the permeation barrier. Whether the laser is effective in improving cutaneous delivery via barrier-defective skin is still unclear. In this study, ablative (Er:YAG) and non-ablative (Er:glass) lasers were examined for the penetration of peptide and siRNA upon topical application on in vitro skin with a healthy or disrupted barrier. An enhanced peptide flux (6.9 fold) was detected after tape stripping of the pig stratum corneum (SC). A further increase of flux to 11.7 fold was obtained after Er:YAG laser irradiation of the SC-stripped skin. However, the application of Er:glass modality did not further raise the flux via the SC-stripped skin. A similar trend was observed in the case of psoriasiform skin. Conversely, the flux was enhanced 3.7 and 2.6 fold after treatment with the Er:YAG and the Er:glass laser on the atopic dermatitis (AD)-like skin. The 3-D skin structure captured by confocal microscopy proved the distribution of peptide and siRNA through the microchannels and into the surrounding tissue. The fractional laser was valid for ameliorating macromolecule permeation into barrier-disrupted skin although the enhancement level was lower than that of normal skin.

  15. Development and characterisation of chitosan films impregnated with insulin loaded PEG-b-PLA nanoparticles (NPs): a potential approach for buccal delivery of macromolecules.

    Science.gov (United States)

    Giovino, Concetta; Ayensu, Isaac; Tetteh, John; Boateng, Joshua S

    2012-05-30

    Mucoadhesive chitosan based films, incorporated with insulin loaded nanoparticles (NPs) made of poly(ethylene glycol)methyl ether-block-polylactide (PEG-b-PLA) have been developed and characterised. Blank-NPs were prepared by double emulsion solvent evaporation technique with varying concentrations of the copolymer (5 and 10%, w/v). The optimised formulation was loaded with insulin (model protein) at initial loadings of 2, 5 and 10% with respect to copolymer weight. The developed NPs were analysed for size, size distribution, surface charge, morphology, encapsulation efficiency and drug release. NPs showing negative (ζ)-potential ( 300 nm and a polydispersity index (P.I.) of ≈ 0.2, irrespective of formulation process, were achieved. Insulin encapsulation efficiencies of 70% and 30% for NPs-Insulin-2 and NPs-Insulin-5 were obtained, respectively. The in vitro release behaviour of both formulations showed a classic biphasic sustained release of protein over 5 weeks which was influenced by pH of the release medium. Optimised chitosan films embedded with 3mg of insulin loaded NPs were produced by solvent casting with homogeneous distribution of NPs in the mucoadhesive matrix, which displayed excellent physico-mechanical properties. The drug delivery system has been designed as a novel platform for potential buccal delivery of macromolecules. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Semiconducting icosahedral boron arsenide crystal growth for neutron detection

    Science.gov (United States)

    Whiteley, C. E.; Zhang, Y.; Gong, Y.; Bakalova, S.; Mayo, A.; Edgar, J. H.; Kuball, M.

    2011-03-01

    Semiconducting icosahedral boron arsenide, B12As2, is an excellent candidate for neutron detectors, thermoelectric converters, and radioisotope batteries, for which high quality single crystals are required. Thus, the present study was undertaken to grow B12As2 crystals by precipitation from metal solutions (nickel) saturated with elemental boron (or B12As2 powder) and arsenic in a sealed quartz ampoule. B12As2 crystals of 10-15 mm were produced when a homogeneous mixture of the three elements was held at 1150 °C for 48-72 h and slowly cooled (3.5 °C/h). The crystals varied in color and transparency from black and opaque to clear and transparent. X-ray topography (XRT), and elemental analysis by energy dispersive X-ray spectroscopy (EDS) confirmed that the crystals had the expected rhombohedral structure and chemical stoichiometry. The concentrations of residual impurities (nickel, carbon, etc.) were low, as measured by Raman spectroscopy and secondary ion mass spectrometry (SIMS). Additionally, low etch-pit densities (4.4×107 cm-2) were observed after etching in molten KOH at 500 °C. Thus, the flux growth method is viable for growing large, high-quality B12As2 crystals.

  17. Crystal nucleation initiated by transient ion-surface interactions at aerosol interfaces.

    Science.gov (United States)

    Davis, Ryan D; Tolbert, Margaret A

    2017-07-01

    Particle collisions are a common occurrence in the atmosphere, but no empirical observations exist to fully predict the potential effects of these collisions on air quality and climate projections. The current consensus of heterogeneous crystal nucleation pathways relevant to the atmosphere dictates that collisions with amorphous particles have no effect on the crystallization relative humidity (RH) of aqueous inorganic aerosols because there is no stabilizing ion-surface interaction to facilitate the formation of crystal nuclei. In contrast to this view of heterogeneous nucleation, we report laboratory observations demonstrating that collisions with hydrophobic amorphous organic aerosols induced crystallization of aqueous inorganic microdroplets at high RH, the effect of which was correlated with destabilizing water-mediated ion-specific surface interactions. These same organic aerosols did not induce crystallization once internally mixed in the droplet, pointing toward a previously unconsidered transient ion-specific crystal nucleation pathway that can promote aerosol crystallization via particle collisions.

  18. Microseed matrix screening for optimization in protein crystallization: what have we learned?

    Science.gov (United States)

    D'Arcy, Allan; Bergfors, Terese; Cowan-Jacob, Sandra W; Marsh, May

    2014-09-01

    Protein crystals obtained in initial screens typically require optimization before they are of X-ray diffraction quality. Seeding is one such optimization method. In classical seeding experiments, the seed crystals are put into new, albeit similar, conditions. The past decade has seen the emergence of an alternative seeding strategy: microseed matrix screening (MMS). In this strategy, the seed crystals are transferred into conditions unrelated to the seed source. Examples of MMS applications from in-house projects and the literature include the generation of multiple crystal forms and different space groups, better diffracting crystals and crystallization of previously uncrystallizable targets. MMS can be implemented robotically, making it a viable option for drug-discovery programs. In conclusion, MMS is a simple, time- and cost-efficient optimization method that is applicable to many recalcitrant crystallization problems.

  19. Controlled in meso phase crystallization--a method for the structural investigation of membrane proteins.

    Directory of Open Access Journals (Sweden)

    Jan Kubicek

    Full Text Available We investigated in meso crystallization of membrane proteins to develop a fast screening technology which combines features of the well established classical vapor diffusion experiment with the batch meso phase crystallization, but without premixing of protein and monoolein. It inherits the advantages of both methods, namely (i the stabilization of membrane proteins in the meso phase, (ii the control of hydration level and additive concentration by vapor diffusion. The new technology (iii significantly simplifies in meso crystallization experiments and allows the use of standard liquid handling robots suitable for 96 well formats. CIMP crystallization furthermore allows (iv direct monitoring of phase transformation and crystallization events. Bacteriorhodopsin (BR crystals of high quality and diffraction up to 1.3 Å resolution have been obtained in this approach. CIMP and the developed consumables and protocols have been successfully applied to obtain crystals of sensory rhodopsin II (SRII from Halobacterium salinarum for the first time.

  20. Growth, structural, optical and surface analysis of piperazinium tartrate: A NLO single crystal

    Science.gov (United States)

    Gupta, Apurva; Raseel Rahman M., K.; Nair, Lekha

    2018-05-01

    Single crystal of piperazinium tartrate (PPZT) was grown by the slow evaporation solution growth technique at room temperature. Crystallinity of grown crystal was examined by powder X-ray diffraction. High transparency and wide band gap were observed in the UV-Visible spectroscopic studies. Intense and broad emissions were observed in the blue region, as that is indicated by photoluminescence spectroscopy. The quality of the grown PPZT single crystals were analyzed by the etching studies using the water as the etchant.