WorldWideScience

Sample records for crystal growing techniques

  1. Growing Crystals on the Ceiling.

    Science.gov (United States)

    Christman, Robert A.

    1980-01-01

    Described is a method of studying growing crystals in a classroom utilizing a carrousel projector standing vertically. A saturated salt solution is placed on a slide on the lens of the projector and the heat from the projector causes the water to evaporate and salt to crystalize. (Author/DS)

  2. Czochralski method of growing single crystals. State-of-art

    International Nuclear Information System (INIS)

    Bukowski, A.; Zabierowski, P.

    1999-01-01

    Modern Czochralski method of single crystal growing has been described. The example of Czochralski process is given. The advantages that caused the rapid progress of the method have been presented. The method limitations that motivated the further research and new solutions are also presented. As the example two different ways of the technique development has been described: silicon single crystals growth in the magnetic field; continuous liquid feed of silicon crystals growth. (author)

  3. High-purity germanium crystal growing

    International Nuclear Information System (INIS)

    Hansen, W.L.; Haller, E.E.

    1982-10-01

    The germanium crystals used for the fabrication of nuclear radiation detectors are required to have a purity and crystalline perfection which is unsurpassed by any other solid material. These crystals should not have a net electrically active impurity concentration greater than 10 10 cm - 3 and be essentially free of charge trapping defects. Such perfect crystals of germanium can be grown only because of the highly favorable chemical and physical properties of this element. However, ten years of laboratory scale and commercial experience has still not made the production of such crystals routine. The origin and control of many impurities and electrically active defect complexes is now fairly well understood but regular production is often interrupted for long periods due to the difficulty of achieving the required high purity or to charge trapping in detectors made from crystals seemingly grown under the required conditions. The compromises involved in the selection of zone refining and crystal grower parts and ambients is discussed and the difficulty in controlling the purity of key elements in the process is emphasized. The consequences of growing in a hydrogen ambient are discussed in detail and it is shown how complexes of neutral defects produce electrically active centers

  4. Temperature fields in a growing solar silicon crystal

    Directory of Open Access Journals (Sweden)

    Kondrik A. I.

    2012-06-01

    Full Text Available The optimal thermal terms for growing by Czochralski method Si single-crystals, suitable for making photoelectric energy converters, has been defined by the computer simulation method. Dependences of temperature fields character and crystallization front form on the diameter of the crystal, stage and speed of growing, and also on correlation between diameter and height of the crystal has been studied.

  5. Growing Larger Crystals for Neutron Diffraction

    Science.gov (United States)

    Pusey, Marc

    2003-01-01

    Obtaining crystals of suitable size and high quality has been a major bottleneck in macromolecular crystallography. With the advent of advanced X-ray sources and methods the question of size has rapidly dwindled, almost to the point where if one can see the crystal then it was big enough. Quality is another issue, and major national and commercial efforts were established to take advantage of the microgravity environment in an effort to obtain higher quality crystals. Studies of the macromolecule crystallization process were carried out in many labs in an effort to understand what affected the resultant crystal quality on Earth, and how microgravity improved the process. While technological improvements are resulting in a diminishing of the minimum crystal size required, neutron diffraction structural studies still require considerably larger crystals, by several orders of magnitude, than X-ray studies. From a crystal growth physics perspective there is no reason why these 'large' crystals cannot be obtained: the question is generally more one of supply than limitations mechanism. This talk will discuss our laboratory s current model for macromolecule crystal growth, with highlights pertaining to the growth of crystals suitable for neutron diffraction studies.

  6. Apparatus for growing HgI.sub.2 crystals

    Science.gov (United States)

    Schieber, Michael M.; Beinglass, Israel; Dishon, Giora

    1978-01-01

    A method and horizontal furnace for vapor phase growth of HgI.sub.2 crystals which utilizes controlled axial and radial airflow to maintain the desired temperature gradients. The ampoule containing the source material is rotated while axial and radial air tubes are moved in opposite directions during crystal growth to maintain a desired distance and associated temperature gradient with respect to the growing crystal, whereby the crystal interface can advance in all directions, i.e., radial and axial according to the crystallographic structure of the crystal. Crystals grown by this method are particularly applicable for use as room-temperature nuclear radiation detectors.

  7. Crystal-Growing Crucible To Suppress Convection

    Science.gov (United States)

    Richter, R.

    1986-01-01

    Platform under growth region stabilizes melt for more uniform crystal growth. In new crucible, platform just below growth interface so melt is too shallow to support convection. Critical depth for onset of pertinent instability calculated from heat flux through surface of melt, volume coefficient of thermal expansion, thermal conductivity, thermal diffusivity, and kinematic viscosity.

  8. Scanning electron microscope view of iron crystal growing on pyroxene crystal

    Science.gov (United States)

    1972-01-01

    A scanning electron microscope photograph of a four-micron size iron crystal growing on a pyroxene crystal (calcium-magnesium-iron silicate) from the Apollo 15 Hadley-Apennino lunar landing site. The well developed crystal faces indicate that the crystal was formed from a hot vapor as the rock was cooling.

  9. JAXA protein crystallization in space: ongoing improvements for growing high-quality crystals

    International Nuclear Information System (INIS)

    Takahashi, Sachiko; Ohta, Kazunori; Furubayashi, Naoki; Yan, Bin; Koga, Misako; Wada, Yoshio; Yamada, Mitsugu; Inaka, Koji; Tanaka, Hiroaki; Miyoshi, Hiroshi; Kobayashi, Tomoyuki; Kamigaichi, Shigeki

    2013-01-01

    The Japan Aerospace Exploration Agency’s 'high-quality protein crystal growth' project is introduced. If crystallization conditions were carefully fixed in ground-based experiments, high-quality protein crystals grew in microgravity in many experiments on the International Space Station, especially when a highly homogeneous protein sample and a viscous crystallization solution were employed. The Japan Aerospace Exploration Agency (JAXA) started a high-quality protein crystal growth project, now called JAXA PCG, on the International Space Station (ISS) in 2002. Using the counter-diffusion technique, 14 sessions of experiments have been performed as of 2012 with 580 proteins crystallized in total. Over the course of these experiments, a user-friendly interface framework for high accessibility has been constructed and crystallization techniques improved; devices to maximize the use of the microgravity environment have been designed, resulting in some high-resolution crystal growth. If crystallization conditions were carefully fixed in ground-based experiments, high-quality protein crystals grew in microgravity in many experiments on the ISS, especially when a highly homogeneous protein sample and a viscous crystallization solution were employed. In this article, the current status of JAXA PCG is discussed, and a rational approach to high-quality protein crystal growth in microgravity based on numerical analyses is explained

  10. JAXA protein crystallization in space: ongoing improvements for growing high-quality crystals

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Sachiko [Confocal Science Inc., Hayakawa 2nd Building 7F, 2-12-2 Iwamoto-cho, Chiyoda-ku, Tokyo 101-0032 (Japan); Ohta, Kazunori [Japan Aerospace Exploration Agency, 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505 (Japan); Furubayashi, Naoki [Maruwa Foods and Biosciences Inc., 170-1 Tsutsui-cho, Yamatokoriyama, Nara 639-1123 (Japan); Yan, Bin; Koga, Misako [Confocal Science Inc., Hayakawa 2nd Building 7F, 2-12-2 Iwamoto-cho, Chiyoda-ku, Tokyo 101-0032 (Japan); Wada, Yoshio; Yamada, Mitsugu [Japan Aerospace Exploration Agency, 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505 (Japan); Inaka, Koji [Maruwa Foods and Biosciences Inc., 170-1 Tsutsui-cho, Yamatokoriyama, Nara 639-1123 (Japan); Tanaka, Hiroaki, E-mail: tanakah@confsci.co.jp [Confocal Science Inc., Hayakawa 2nd Building 7F, 2-12-2 Iwamoto-cho, Chiyoda-ku, Tokyo 101-0032 (Japan); Miyoshi, Hiroshi; Kobayashi, Tomoyuki; Kamigaichi, Shigeki [Japan Aerospace Exploration Agency, 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505 (Japan)

    2013-11-01

    The Japan Aerospace Exploration Agency’s 'high-quality protein crystal growth' project is introduced. If crystallization conditions were carefully fixed in ground-based experiments, high-quality protein crystals grew in microgravity in many experiments on the International Space Station, especially when a highly homogeneous protein sample and a viscous crystallization solution were employed. The Japan Aerospace Exploration Agency (JAXA) started a high-quality protein crystal growth project, now called JAXA PCG, on the International Space Station (ISS) in 2002. Using the counter-diffusion technique, 14 sessions of experiments have been performed as of 2012 with 580 proteins crystallized in total. Over the course of these experiments, a user-friendly interface framework for high accessibility has been constructed and crystallization techniques improved; devices to maximize the use of the microgravity environment have been designed, resulting in some high-resolution crystal growth. If crystallization conditions were carefully fixed in ground-based experiments, high-quality protein crystals grew in microgravity in many experiments on the ISS, especially when a highly homogeneous protein sample and a viscous crystallization solution were employed. In this article, the current status of JAXA PCG is discussed, and a rational approach to high-quality protein crystal growth in microgravity based on numerical analyses is explained.

  11. Thin film growing by the laser ablation technique: possibilities for growing of dosimetric materials

    International Nuclear Information System (INIS)

    Rojas R, E.M.; Melo M, M.; Enriquez Z, E.; Fernandez G, M.; Haro P, E.; Hernandez P, J.L.

    2005-01-01

    In this talk we will present the basics about the laser ablation technique and how it is used for thin film growing, either as a single film or a stack of thin films, as well as some methods to characterize in real time the film thickness. Finally, we will discuss the possibilities of using laser ablation for growing thin films with applications to dosimetry. (Author)

  12. Celebrating the International Year of Crystallography with a Wisconsin High School Crystal Growing Competition

    Science.gov (United States)

    Guzei, Ilia A.

    2014-01-01

    In honor of the 2014 International Year of Crystallography, the first Wisconsin Crystal Growing Competition was successfully organized and conducted. High school students from 26 schools across the state competed for prizes by growing large crystals of CuSO[subscript4]·5(H[subscript2]O). This paper describes how the event was planned and carried…

  13. A new membrane-based crystallization technique: tests on lysozyme

    Science.gov (United States)

    Curcio, Efrem; Profio, Gianluca Di; Drioli, Enrico

    2003-01-01

    The great importance of protein science both in industrial and scientific fields, in conjunction with the intrinsic difficulty to grow macromolecular crystals, stimulates the development of new observations and ideas that can be useful in initiating more systematic studies using novel approaches. In this regard, an innovative technique, based on the employment of microporous hydrophobic membranes in order to promote the formation of lysozyme crystals from supersaturated solutions, is introduced in this work. Operational principles and possible advantages, both in terms of controlled extraction of solvent by acting on the concentration of the stripping solution and reduced induction times, are outlined. Theoretical developments and experimental results concerning the mass transfer, in vapour phase, through the membrane are presented, as well as the results from X-ray diffraction to 1.7 Å resolution of obtained lysozyme crystals using NaCl as the crystallizing agent and sodium acetate as the buffer. Crystals were found to be tetragonal with unit cell dimensions of a= b=79.1 Å and c=37.9 Å; the overall Rmerge on intensities in the resolution range from 25 to 1.7 Å was, in the best case, 4.4%.

  14. Dynamic light scattering analysis of solutions from which lysozyme crystals grow

    Science.gov (United States)

    Bishop, J. B.; Fredericks, W. J.; Howard, S. B.; Sawada, T.

    1992-08-01

    The variation of the friction factor was measured by photon correlation spectroscopy during isothermal growth of chicken egg white lysozyme crystals. It was observed to initially increase to a maximum as crystals formed, and then to decrease to a constant value. The change in the friction factors was measured as a function of temperature at concentrations of lysozyme varying from one sufficiently low that molecular interactions were undetectable to concentrations near those at which crystals grow in solutions, in all cases the ionic strength was below that required for crystallization.

  15. Dependence of Crystal Quality and β Value on Synthesis Temperature in Growing Gem Diamond Crystals

    International Nuclear Information System (INIS)

    Hong-Yu, Xiao; Xiao-Peng, Jia; Shang-Sheng, Li; Yu, Tian; Ya-Fei, Zhang; Guo-Feng, Huang; Li-Qiu; Hong-An, Ma; Chuan-Yi, Zang

    2008-01-01

    High quality Ib gem diamond single crystals were synthesized in cubic anvil high-pressure apparatus (SPD-6 × 1200) under 5.4 GPa and 1230°C-1280°C. The (100) face of seed crystal was used as growth face, and Ni 70 Mn 25 Co 5 alloy was used as solvent/catalyst. The dependence of crystal quality and β value (the ratio of height to diameter of diamond crystal) on synthesis temperature was studied. When the synthesis temperature is between 1230°C and 1280°C, the β value of the synthetic high-quality gem diamond crystals is between 0.4 and 0.6. The results show that when the β value is between 0.4 and 0.45, the synthetic diamonds are sheet-shape crystals; however, when the β value is between 0.45 and 0.6, the synthetic diamonds are tower-shape crystals. In addition, when the β value is less than 0.4, skeleton crystals will appear. When the β value is more than 0.6, most of the synthetic diamond crystals are inferior crystals

  16. Generic technique to grow III-V semiconductor nanowires in a closed glass vessel

    Directory of Open Access Journals (Sweden)

    Kan Li

    2016-06-01

    Full Text Available Crystalline III-V semiconductor nanowires have great potential in fabrication of nanodevices for applications in nanoelectronics and optoelectronics, and for studies of novel physical phenomena. Sophisticated epitaxy techniques with precisely controlled growth conditions are often used to prepare high quality III-V nanowires. The growth process and cost of these experiments are therefore dedicated and very high. Here, we report a simple but generic method to synthesize III-V nanowires with high crystal quality. The technique employs a closed evacuated tube vessel with a small tube carrier containing a solid source of materials and another small tube carrier containing a growth substrate inside. The growth of nanowires is achieved after heating the closed vessel in a furnace to a preset high temperature and then cooling it down naturally to room temperature. The technique has been employed to grow InAs, GaAs, and GaSb nanowires on Si/SiO2 substrates. The as-grown nanowires are analyzed by SEM, TEM and Raman spectroscopy and the results show that the nanowires are high quality zincblende single crystals. No particular condition needs to be adjusted and controlled in the experiments. This technique provides a convenient way of synthesis of III-V semiconductor nanowires with high material quality for a wide range of applications.

  17. Method of synthesizing and growing copper-indium-diselenide (CuInSe/sub 2/) crystals

    Science.gov (United States)

    Ciszek, T.F.

    1984-11-29

    A process for preparing CuInSe/sub 2/ crystals includes melting a sufficient quantity of B/sub 2/O/sub 2/ along with stochiometric quantities of Cu, In, and Se in a crucible in a high-pressure atmosphere of inert gas to encapsulate the CuInSe/sub 2/ melt and confine the Se to the crucible. Additional Se in the range of 1.8 to 2.2% over the stochiometric quantity is preferred to make up for small amounts of Se lost in the process. The melt can then be cooled slowly to form the crystal as direct solidification, or the crystal can be grown by inserting a seed crystal through the B/sub 2/O/sub 3/ encapsulate into contact with the CuInSe/sub 2/ melt and withdrawing the seed upwardly to grow the crystal thereon from the melt.

  18. Method of synthesizing and growing copper-indium-diselenide (CuInSe.sub.2) crystals

    Science.gov (United States)

    Ciszek, Theodore F.

    1987-01-01

    A process for preparing CuInSe.sub.2 crystals includes melting a sufficient quantity of B.sub.2 O.sub.3 along with stoichiometric quantities of Cu, In, and Se in a crucible in a high pressure atmosphere of inert gas to encapsulate the CuInSe.sub.2 melt and confine the Se to the crucible. Additional Se in the range of 1.8 to 2.2 percent over the stoichiometric quantity is preferred to make up for small amounts of Se lost in the process. The crystal is grown by inserting a seed crystal through the B.sub.2 O.sub.3 encapsulate into contact with the CuInSe.sub.2 melt and withdrawing the seed upwardly to grow the crystal thereon from the melt.

  19. Effect of Different Crystallization Techniques on the Dissolution ...

    African Journals Online (AJOL)

    HP

    Methods: Ketoprofen crystals were prepared by various crystallization technique including spherical .... infrared. (FTIR) spectroscopy. FTIR spectral measurements were taken at ambient temperature (Shimadzu, model 8033,. USA). About 2 mg of the pure drug, as well as ... stored samples and the data compared with.

  20. Addressing techniques of liquid crystal displays

    CERN Document Server

    Ruckmongathan, Temkar N

    2014-01-01

    Unique reference source that can be used from the beginning to end of a design project to aid choosing an appropriate LCD addressing technique for a given application This book will be aimed at design engineers who are likely to embed LCD drivers and controllers in many systems including systems on chip. Such designers face the challenge of making the right choice of an addressing technique that will serve them with best performance at minimal cost and complexity. Readers will be able to learn about various methods available for driving matrix LCDs and the comparisons at the end of each chap

  1. Advanced crystal growth techniques for thallium bromide semiconductor radiation detectors

    Science.gov (United States)

    Datta, Amlan; Becla, Piotr; Guguschev, Christo; Motakef, Shariar

    2018-02-01

    Thallium Bromide (TlBr) is a promising room-temperature radiation detector candidate with excellent charge transport properties. Currently, Travelling Molten Zone (TMZ) technique is widely used for growth of semiconductor-grade TlBr crystals. However, there are several challenges associated with this type of crystal growth process including lower yield, high thermal stress, and low crystal uniformity. To overcome these shortcomings of the current technique, several different crystal growth techniques have been implemented in this study. These include: Vertical Bridgman (VB), Physical Vapor Transport (PVT), Edge-defined Film-fed Growth (EFG), and Czochralski Growth (Cz). Techniques based on melt pulling (EFG and Cz) were demonstrated for the first time for semiconductor grade TlBr material. The viability of each process along with the associated challenges for TlBr growth has been discussed. The purity of the TlBr crystals along with its crystalline and electronic properties were analyzed and correlated with the growth techniques. Uncorrected 662 keV energy resolutions around 2% were obtained from 5 mm x 5 mm x 10 mm TlBr devices with virtual Frisch-grid configuration.

  2. INDUSTRIAL CRYSTALLIZATION AND PRECIPITATION FROM SOLUTIONS: STATE OF THE TECHNIQUE

    Directory of Open Access Journals (Sweden)

    Giulietti M.

    2001-01-01

    Full Text Available Crystallization and precipitation from solutions are responsible for 70% of all solid materials produced by the chemical industry. Competing with distillation as a separation and purification technique, their use is widespread. They operate at low temperatures with low energy consumption and yield with high purifications in one single step. Operational conditions largely determine product quality in terms of purity, filterability, flowability and reactivity. Producing a material with the desired quality often requires a sound knowledge of the elementary steps involved in the process: creation of supersaturation, nucleation, crystal growth, aggregation and other secondary processes. Mathematical models coupling these elementary processes to all particles in a crystallizer have been developed to design and optimize crystallizer operation. For precipitation, the spatial distribution of reactants and particles in the reactor is important; thus the tools of computational fluid dynamics are becoming increasingly important. For crystallization of organic chemicals, where incorporation of impurities and crystal shape are critical, molecular modeling has recently appeared as a useful tool. These theoretical developments must be coupled to experimental data specific to each material. Theories and experimental techniques of industrial crystallization and precipitation from solutions are reviewed, and recent developments are highlighted.

  3. Zinc Oxide Nano crystals Synthesized by Quenching Technique

    International Nuclear Information System (INIS)

    Norhayati Abu Bakar; Akrajas Ali Umar; Muhamad Mat Salleh; Muhammad Yahya

    2011-01-01

    This paper reports an attempt to synthesize non toxic zinc oxide (ZnO) nano crystals using a simple quenching technique. The hot zinc oxide powder was quenched in hexane solution to obtain ZnO nano crystals. As the result, diameter size of the synthesized ZnO is 200 nm. It was also exhibited a good crystalline with wurtzite phase. The nano crystals properties of ZnO were revealed from good absorbance and green luminescence under UV exposure. This may be related with oxygen vacancy ionization during the annealing process. (author)

  4. Development of low-cost silicon crystal growth techniques for terrestrial photovoltaic solar energy conversion

    Science.gov (United States)

    Zoutendyk, J. A.

    1976-01-01

    Because of the growing need for new sources of electrical energy, photovoltaic solar energy conversion is being developed. Photovoltaic devices are now being produced mainly from silicon wafers obtained from the slicing and polishing of cylindrically shaped single crystal ingots. Inherently high-cost processes now being used must either be eliminated or modified to provide low-cost crystalline silicon. Basic to this pursuit is the development of new or modified methods of crystal growth and, if necessary, crystal cutting. If silicon could be grown in a form requiring no cutting, a significant cost saving would potentially be realized. Therefore, several techniques for growth in the form of ribbons or sheets are being explored. In addition, novel techniques for low-cost ingot growth and cutting are under investigation.

  5. Growth kinetics of protein single crystals in the gel acupuncture technique

    Science.gov (United States)

    García-Ruiz, Juan Manuel; Moreno, Abel

    1997-07-01

    The growth of single crystals of tetragonal HEW lysozyme and thaumatin I into glass capillaries was monitored by time lapse video-microscopy. The crystals were obtained by unidirectional transport of the precipitating agent through capillaries of internal diameter ranging from 0.2 to 1.2 mm, using the gel acupuncture technique. For crystals growing from true protein solutions, the measured average growth rates varies with capillary diameter from 1.7 to 3.7 Å/s for thaumatin and from 2.8 to 22 Å/s for lysozyme. The measured average growth rates for crystals growing into gelled protein solutions were 1.8 Å/s for thaumatin and 2.5 Å/s for lysozyme. The trend in the variation of the growth rate with time is similar and suggests that, for capillaries with internal radius lower than 0.8 mm, diffusion dominates the global mass transport control. However, the existence of convection rolls near the crystal-solution interface and close to zones with high density gradient cannot be discarded.

  6. Growth and evaluation of lanthanoids orthoniobates single crystals processed by a miniature pedestal growth technique

    International Nuclear Information System (INIS)

    Octaviano, E.S.; Reyes Ardila, D.; Andrade, L.H.C.; Siu Li, M.; Andreeta, J.P.

    2004-01-01

    Optimized conditions for the growth of lanthanoids orthoniobates (LnNbO 4 , Ln=lanthanide elements) single crystal minirods by a floating zone technique were investigated. Adequate atmospheres and pulling to feeding speed ratios to grow these materials were determined. Emphasis is given to the study of LaNbO 4 because of their more favorable growth conditions and crystalline quality. This material can be efficiently doped with rare earth elements such as erbium. It grows with high crystallinity and its preferential growth direction is [110]. A preliminary evaluation of optical properties of Er 3+ -doped LaNbO 4 single crystal under the Judd-Ofelt formalism indicates spectral parameters Ω t close and even larger than for Er 3+ ions in YVO 4 . (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Procedure for growing Bi4Ge3O12 bismuth germanate single crystals with suppressed growth defects

    International Nuclear Information System (INIS)

    Zikmund, J.; Blazek, K.; Jarolimek, O.; Horak, J.

    1991-01-01

    The method developed allows high-quality scintillator material to be grown reproducibly by the Czochralski method. The crystals attain diameters up to 80 mm and lengths up to 200 mm. The growth is performed on instruments equipped with devices for continuous measurement of weight increments of the growing crystals with a precision better than 10 mg. The growth parameters are controlled with a computer and based on actual data. The crystals are grown using an axial temperature gradient within the range of 25 to 35 degC/cm and a constant drawing rate within the range of 0.5 to 1.2 mm/h. An interface shape suitable for the suppression of defect development is achieved through a combination of the weight increment and rotation of the crystal. (M.D.)

  8. Current developments in CZ Si crystal growing technology; Aktuelle Entwicklungen in der Zuechtungstechnologie von CZ-Si-Kristallen

    Energy Technology Data Exchange (ETDEWEB)

    Altekrueger, Burkhard; Volk, Michael [PVA TePla AG, Wettenberg (Germany)

    2011-02-15

    The industrial growing of increasingly large and perfect silicon (Si) monocrystals for applications in microelectronics and photovoltaics requires continuous improvement of process control and growing technology. Continuous adaptation and optimization of system technology in terms of reliability, process flexibility and dimensioning are also necessary. The basic principles of industrial silicon crystal growing and the resultant requirements for the Si process and system technologies are described in the first part of this series of articles. The constantly increasing requirements for the performance and complexity of the electronic circuits (chips) in accordance with Moore's Law mean that the requirements for the perfection and dimensions of monocrystalline Si wafers and Si crystals are also continuously rising. After the introduction of the 300 mm Si wafer generation in recent years, the next Si wafer generation (450 mm) is therefore being discussed already. The technological and economic effects of these constantly increasing requirements for the necessary system technologies will be set out and discussed in the subsequent articles on the basis of current Si CZ crystal growing systems as well as new system concepts. (orig.)

  9. Influence of gravitational and vibrational convection on the heat- and mass transfer in the melt during crystal growing by Bridgman and floating zone methods

    Science.gov (United States)

    Fedorov, Oleg

    2016-07-01

    Space materials science is one of the priorities of different national and international space programs. The physical processes of heat and mass transfer in microgravity (including effect of g-jitter) is far from complete clarity, especially for important practical technology for producing crystals from the melt. The idea of the impact on crystallizing melt by low frequency vibration includes not only the possibility to suppress unwanted microaccelerations, but also to actively influence the structure of the crystallization front. This approach is one of the most effective ways to influence the quality of materials produced in flight conditions. The subject of this work is the effect of vibrations on the thermal and hydrodynamic processes during crystal growth using Bridgman and floating zone techniques, which have the greatest prospect of practical application in space. In the present approach we consider the gravitational convection, Marangoni convection, as well as the effect of vibration on the melt for some special cases. The results of simulation were compared with some experimental data obtained by the authors using a transparent model substance - succinonitrile (Bridgman method), and silicon (floating zone method). Substances used, process parameters and characteristics of the experimental units correspond the equipment developed for onboard research and serve as a basis for selecting optimum conditions vibration exposure as a factor affecting the solidification pattern. The direction of imposing vibrations coincides with the axis of the crystal, the frequency is presented by the harmonic law, and the force of gravity was varied by changing its absolute value. Mathematical model considered axisymmetric approximation of joint convective-conductive energy transfer in the system crystal - melt. Upon application of low-frequency oscillations of small amplitude along the axis of growing it was found the suppression of the secondary vortex flows near the

  10. New technique of manipulating a protein crystal using adhesive material

    International Nuclear Information System (INIS)

    Kitatani, Tomoya; Sugiyama, Shigeru; Matsumura, Hiroyoshi

    2008-01-01

    We have developed Crystal Catcher, a new device for manipulating protein crystals. Crystal Catcher directly captures a crystal with an adhesive. The easy and stable removal of a protein crystal from a drop has been achieved using the Crystal Catcher. The crystal picked up on the Crystal Catcher is positioned in the cryostream on a goniometer and flash-cooled. Various protein crystals can be captured and mounted without causing significant damage. This new approach will replace nylon loops for picking up protein crystals. (author)

  11. New techniques for growing anaerobic bacteria: experiments with Clostridium butyricum and Clostridium acetobutylicum

    International Nuclear Information System (INIS)

    Adler, H.I.; Crow, W.D.; Hadden, C.T.; Hall, J.; Machanoff, R.

    1983-01-01

    Stable membrane fragments derived from Escherichia coli produce and maintain strict anaerobic conditions when added to liquid or solid bacteriological media. Techniques for growing Clostridium butyricum and Clostridium acetobutylicum in membrane-containing media are described. Liquid cultures initiated by very small inocula can be grown in direct contact with air. In solid media, colonies develop rapidly from individual cells even without incubation in anaerobic jars or similar devices. Observations on growth rates, spontaneous mutations, radiation, and oxygen sensitivity of anaerobic bacteria have been made using these new techniques

  12. Redox process catalysed by growing crystal-strengite, FePO4,2H2O, crystallizing from solution with iron(II) and hydroxylamine

    Science.gov (United States)

    Lundager Madsen, Hans Erik

    2014-09-01

    In an attempt to grow pure crystals of the iron(II) phosphate vivianite, Fe3(PO4)2,8H2O, from a solution of Mohr's salt, Fe(NH4)2(SO4)2,6H2O, added to a solution of ammonium phosphate, hydroxylammonium chloride, NH3OHCl, was added to the iron(II) stock solution to eliminate oxidation of iron(II) by oxygen from the air. However, the effect turned out to be the opposite of the expected: whereas hydroxylamine reduces iron(III) in bulk solution, it acted as a strong oxidant in the presence of growing iron phosphate crystals, causing the crystallization of the iron(III) phosphate strengite, FePO4,2H2O, as the only solid phase. Evidently the crystal surface catalyses oxidation of iron(II) by hydroxylamine. The usual composite kinetics of spiral growth and surface nucleation was found. The surface-nucleation part yielded edge free energy λ in the range 12-45 pJ/m, virtually independent of temperature and in the range typical for phosphates of divalent metals. The scatter of values for λ presumably arises from contributions from different crystal forms to the overall growth rate. The low mean value points to strong adsorption of iron(II), which is subsequently oxidized at the crystal surface, forming strengite. The state of the system did not tend to thermodynamic equilibrium, but to a metastable state, presumably controlled by the iron(II) rich surface layer of the crystal. In addition to crystal growth, it was possible to measure nucleation kinetics by light scattering (turbidimetry). A point of transition from heterogeneous to homogeneous nucleation was found, and from the results for the homogeneous domain a rather precise value of crystal surface free energy γ=55 mJ/m2 was found. This is a relatively low value as well, indicating that the redox process plays a role already at the nucleation stage.

  13. Small-angle neutron scattering technique in liquid crystal studies

    International Nuclear Information System (INIS)

    Shahidan Radiman

    2005-01-01

    The following topics discussed: general principles of SAS (Small-angle Neutron Scattering), liquid crystals, nanoparticle templating on liquid crystals, examples of SAS results, prospects of this studies

  14. Region-growing technique adapted to precise microcalcification characterization in mammography

    Science.gov (United States)

    Darboux, Michel; Dinten, Jean-Marc; Nicolas, Eric

    1996-11-01

    The early detection of breast cancer is essential for increasing the survival rate of the disease. Today, mammography is the only breast screening technique capable of detecting breast cancer at a very early stage. The presence of a breast tumor is indicated by some features on the mammogram. One sign of malignancy is the presence of clusters of fine, granular microcalcifications. We present here a three-step method for detecting and characterizing these microcalcifications. We begin with the detection of potential candidates. The aim of this first step is to detect all the pixels that could be a microcalcification. Then we focus on our specific region growing technique which provides an accurate extraction of the shape of the region corresponding to each detected growing technique which provides an accurate extraction of the shape of the region corresponding to each detected seed. This second step is essential because microcalcifications shape is a very important feature for the diagnosis. It is then possible to determine precise parameters to characterize these microcalcifications. This three-step method has been evaluated on a set of images form the mammographic image analysis society database.

  15. Method of growing yttrium aluminate and/or lanthanide single crystals with perovskite structure

    International Nuclear Information System (INIS)

    Kvapil, Jiri; Perner, B.; Kvapil, Josef; Blazek, K.

    1989-01-01

    Single crystals of yttrium aluminate and/or lanthanide with perovskite structure are grown from melt in a vacuum at a pressure of gas residues of max. 0.01 Pa. The melt contains 1±0.05 gram-ions of aluminium per gram-ion of yttrium and/or lanthanides. The single crystals are then heated in a vacuum (0.01 Pa) at temperatures of 1,450 to 1,800 degC for 2 to 3 hours. (B.S.)

  16. A region growing technique adapted to precise micro calcification characterization in mammography

    Energy Technology Data Exchange (ETDEWEB)

    Darboux, M.; Dinten, J.M.; Nicolas, E.

    1996-12-31

    To-day, mammography is the only breast screening technique capable of detecting breast cancer at a very early stage. The presence of a breast tumor is indicated by some features on the mammogram. One sign of malignancy is the presence of clusters of fine, granular micro-calcifications. We present here a new three-step method for detecting and characterizing these micro-calcifications. We design with the detection of potential candidates (`seeds`). The aim of this first step is to detect all the pixels be a micro-calcification. Then we focus on our specific region growing technique which provides an accurate extraction of the shape of the region corresponding to each detected seed. This second step is essential because micro-calcifications shape is a very important feature for the diagnosis. It is then possible to determine precise parameters to characterize these micro-calcifications. (authors). 4 refs.

  17. Effect of irrigation techniques and strategies on water footprint of growing crops

    Science.gov (United States)

    Chukalla, A. D.; Krol, M. S.; Hoekstra, A. Y. Y.

    2014-12-01

    technique. This rank though changes in non-moisture limiting condition (wet year) drip performing better in reducing the WF of growing crops than sub-surface drip. It was observed that with all range of irrigation techniques, strategies and field management practices there is more room in reducing the WF of growing crops in loam than sandy-loam soil.

  18. Growth and characterization of 4-chloro-3-nitrobenzophenone single crystals using vertical Bridgman technique

    Energy Technology Data Exchange (ETDEWEB)

    Aravinth, K., E-mail: anandcgc@gmail.com; Babu, G. Anandha, E-mail: anandcgc@gmail.com; Ramasamy, P., E-mail: anandcgc@gmail.com [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam -603110, Tamilnadu (India)

    2014-04-24

    4-chloro-3-nitrobenzophenone (4C3N) has been grown by using vertical Bridgman technique. The grown crystal was confirmed by Powder X-ray diffraction analysis. The crystalline perfection of the grown crystal was examined by high-resolution X-ray diffraction study. The fluorescence spectra of grown 4C3N single crystals exhibit emission peak at 575 nm. The micro hardness measurements were used to analyze the mechanical property of the grown crystal.

  19. Effect of Different Crystallization Techniques on the Dissolution ...

    African Journals Online (AJOL)

    HP

    Pure drug and all the prepared crystals In each case, the sample was dispersed in potassium bromide. (KBr) powder and compressed to pellets at a pressure of 6000 kg/cm2. X-ray diffraction analysis. X-ray powder diffraction patterns were obtained to detect possible polymorphic transitions during the crystallization process.

  20. Analysis of water application techniques for growing tomatoes in small pots on different substrates. Note 2

    Directory of Open Access Journals (Sweden)

    Luigi Cavazza

    Full Text Available The response of the tomato plants to the irrigation regimes compared in the previous study, particularly when compared with the response to the peat fraction in the mixture, was modest, often irregular and subject to complex interactions with the former factor. This result could depend partially on the fact that the parameters for the water regime applied during the trials were chosen to prevent exposing the plants to excessive stress through lack of water or excess water. This note analyses the technique used to apply the water. Two main water application parameters were identified parameter a expressing the mean moisture level of the pot during growing, and parameter b expressing the amplitude of the variation in moisture level between the irrigation threshold and the level to which the water was topped up at each watering. The actual mean volume of irrigation during the cultivation period was compared with the theoretically predicted value and the discrepancy explained. The role of parameter a and b are proposed to define the irrigation regime applied and the water regime as such can be defined by these two parameters a and b, as a general composite index. Furthermore the effect on the biological performance of both parameters a and b were studied obtaining a clearer picture of the effect of the water regime. The role of both parameters, a and b were synthesized in a specific composite index for each individual characteristic of the plant after taking in account the principal causes of their variations.

  1. A novel lattice energy calculation technique for simple inorganic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kaya, Cemal [Department of Chemistry, Faculty of Science, Cumhuriyet University, 58140 Sivas (Turkey); Kaya, Savaş, E-mail: savaskaya@cumhuriyet.edu.tr [Department of Chemistry, Faculty of Science, Cumhuriyet University, 58140 Sivas (Turkey); Banerjee, Priyabrata [Surface Engineering and Tribology Group, CSIR-Central Mechanical Engineering Research Institute, Mahatma Gandhi Avenue, Durgapur 713209 (India)

    2017-01-01

    In this pure theoretical study, a hitherto unexplored equation based on Shannon radii of the ions forming that crystal and chemical hardness of any crystal to calculate the lattice energies of simple inorganic ionic crystals has been presented. To prove the credibility of this equation, the results of the equation have been compared with experimental outcome obtained from Born-Fajans-Haber- cycle which is fundamentally enthalpy-based thermochemical cycle and prevalent theoretical approaches proposed for the calculation of lattice energies of ionic compounds. The results obtained and the comparisons made have demonstrated that the new equation is more useful compared to other theoretical approaches and allows to exceptionally accurate calculation of lattice energies of inorganic ionic crystals without doing any complex calculations.

  2. SdsA polymorph isolation and improvement of their crystal quality using nonconventional crystallization techniques

    Energy Technology Data Exchange (ETDEWEB)

    De la Mora, Eugenio; Flores-Hernández, Edith; Jakoncic, Jean; Stojanoff, Vivian; Siliqi, Dritan; Sánchez-Puig, Nuria; Moreno, Abel

    2015-09-20

    SdsA, a sodium dodecyl sulfate hydrolase, from Pseudomonas aeruginosa was crystallized in three different crystal polymorphs and their three-dimensional structure was determined. The different polymorphs present different crystal packing habits. One of the polymorphs suggests the existence of a tetramer, an oligomeric state not observed previously, while the crystal packing of the remaining two polymorphs obstructs the active site entrance but stabilizes flexible regions of the protein. Nonconventional crystallization methods that minimize convection, such as counterdiffusion in polyvinyl alcohol gel coupled with the influence of a 500 MHz (10.2 T) magnetic field, were necessary to isolate the poorest diffracting polymorph and increase its internal order to determine its structure by X-ray diffraction. In conclusion, the results obtained show the effectiveness of nonconventional crystallographic methods to isolate different crystal polymorphs.

  3. Thermal node of the growth vessel of apparatus of large-sized crystals of germanium growing by the immersible pivoted shaper method

    International Nuclear Information System (INIS)

    Bogomaz, A.V.; Krytskaja, T.V.; Karpenko, A.V.

    2013-01-01

    The construction of a thermal knot of the growth vessel of apparatus of large-sized crystals of germanium growing by the immersible pivoted shaper method is developed and tested. In a construction as a bowl material carbon and carbon-carbon composite bodied by pyrolytic carbon are used. Series of advantages of bowls from carbon-carbon composite material in the part of assurance of the given allocation of temperature on a surface of a bowl, heightening of a mechanical strength and fraction soot impurities lowering in a crystal is fixed. In experimental-industrial conditions crystals of germanium in diameter to 420 mm with high optical characteristic are received

  4. Shape of growing crystals of primary phases in autectic alloys of Fe - Fe2B and Ni - Ni3B systems

    International Nuclear Information System (INIS)

    Tavadze, F.N.; Garibashvili, V.I.; Nakaidze, Sh.G.

    1983-01-01

    Shapes of Fe 2 B and Ni 3 B crystal growth in eutectic Fe-B and Ni-B system alloys are considered. Iron hemiboride primary crystals take the form of a plane-face phase boundary and inherit a tetragonal prismatic lattice. After the crystal attains the critical size the dendritic branching occurs resulting in formation of a typical sceleton dendrite. Comparison of data obtained with entropy of melting for Fe 2 B and Ni 3 B borides shows that FeB crystals during the growth should take the spherical form. It is stated that the shape of growing crystals in Fe-Fe 2 B and Ni-Ni 2 B eutectic colonies is determined by the shape of borides

  5. Preparation of HfC single crystals by a floating zone technique

    International Nuclear Information System (INIS)

    Otani, S.; Tanaka, T.

    1981-01-01

    HfC single crystals have been prepared using a floating zone technique by controlling the compositions of the initial molten zone and the feed rod. The obtained crystal rods were 6 cm long and 0.9 cm in diameter. The various parts of the crystal rods have nearly constant compositions (C/Hf(ZR) = 0.956-0.977), and do not contain any free carbon. The impurities in the crystal, evaporation product, and starting material were examined by fluorescence X-ray spectroscopy. The refining effect due to evaporation was discussed. (orig.)

  6. Quartz Crystal Microbalance with Dissipation (QCM-D) studies of the viscoelastic response from a continuously growing grafted polyelectrolyte layer.

    Science.gov (United States)

    Dunér, Gunnar; Thormann, Esben; Dėdinaitė, Andra

    2013-10-15

    Poly(acrylic acid) was grown from substrates by photopolymerization, and the grafting process was monitored in situ by Quartz Crystal Microbalance with Dissipation (QCM-D) measurements in a 1:1 v/v mixture of water/ethanol. The polymerization process was monitored into the thick film region, where the change in frequency and dissipation with increasing film mass changes sign as predicted by the Voigt viscoelastic model. Our experimental data are compared with predictions of this model, and satisfactory agreement is found for low overtone numbers. The Voigt model was applied to analyze the measured changes in frequency, Δf, and dissipation, ΔD, in order to extract information on layer thickness, shear elasticity, μ, and shear viscosity, η, of the growing film. The increasing rate of changes in Δf and ΔD observed after about 150s of polymerization was found to correlate with an increasing growth rate of the film thickness. For longer polymerization times a close to linear increase in thickness with time was observed. The sensitivity, defined as the derivatives of Δf and ΔD with respect to thickness, depends on overtone number and is different for the frequency and dissipation signals - facts that should be considered when investigating small changes in thick films used in e.g. sensor applications. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. Interfacial wave theory for dendritic structure of a growing needle crystal. I - Local instability mechanism. II - Wave-emission mechanism at the turning point

    Science.gov (United States)

    Xu, Jian-Jun

    1989-01-01

    The complicated dendritic structure of a growing needle crystal is studied on the basis of global interfacial wave theory. The local dispersion relation for normal modes is derived in a paraboloidal coordinate system using the multiple-variable-expansion method. It is shown that the global solution in a dendrite growth process incorporates the morphological instability factor and the traveling wave factor.

  8. Shaped single crystal grow and scintillation properties of Bi:GD.sub.3./sub.Ga.sub.5./sub.O.sub.12./sub..

    Czech Academy of Sciences Publication Activity Database

    Novoselov, A.; Yoshikawa, A.; Nikl, Martin; Solovieva, Natalia; Fukuda, T.

    2005-01-01

    Roč. 537, - (2005), s. 247-250 ISSN 0168-9002 R&D Projects: GA AV ČR(CZ) KSK1010104 Institutional research plan: CEZ:AV0Z10100521 Keywords : garnet * shaped single crystal grow * luminescent properties * Bi 3+ Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.224, year: 2005

  9. Application of feedback control and in situ milling to improve particle size and shape in the crystallization of a slow growing needle-like active pharmaceutical ingredient.

    Science.gov (United States)

    Yang, Yang; Pal, Kanjakha; Koswara, Andy; Sun, Qingqing; Zhang, Yuqi; Quon, Justin; McKeown, Rahn; Goss, Charles; Nagy, Zoltan K

    2017-11-25

    Control of crystal size and shape is crucially important for crystallization process development in the pharmaceutical industries. In general crystals of large size and low aspect ratio are desired for improved downstream manufacturability. It can be extremely challenging to design crystallization processes that achieve these targets for active pharmaceutical ingredients (APIs) that have very slow growth kinetics and needle-like morphology. In this work, a batch cooling crystallization process for a GlaxoSmithKline patented API, which is characterized by very slow growth rate and needle morphology, was studied and improved using process analytical technology (PAT) based feedback control techniques and in situ immersion milling. Four specific approaches were investigated: Supersaturation control (SSC), direct nucleation control (DNC), sequential milling-DNC, and simultaneous milling-DNC. This is the first time that immersion wet milling is combined with feedback control in a batch crystallization process. All four approaches were found to improve crystal size and/or shape compared to simple unseeded or seeded linear cooling crystallizations. DNC provided higher quality crystals than SSC, and sequential and simultanesou milling-DNC approaches could reduce particle 2D aspect ratio without generating too much fines. In addition, an ultra-performance liquid chromatography (UPLC) system was used online as a novel PAT tool in the crystallization study. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Growth and characterization of organometallic L-alanine cadmium chloride single crystal by slow evaporation technique

    International Nuclear Information System (INIS)

    Bright, K.C.; Freeda, T.H.

    2010-01-01

    Single crystals of L-alanine cadmium chloride (LACC), an organometallic nonlinear optical material, have been grown by the slow evaporation technique. The grown crystals were subjected to various characterization techniques, such as single crystal and powder XRD, FTIR, UV-vis and TGA-DTA. The mechanical properties of the crystals show that this material belongs to the category of hard materials. Second harmonic generation was confirmed by the Kurtz and Perry powder technique. Electrical parameters, such as dielectric constant, dielectric loss, ac and dc conductivity and their corresponding activation energies have been studied. The low dielectric constant and dielectric loss suggest that this material is a good candidate for micro-electronic applications.

  11. A standardized technique for high-pressure cooling of protein crystals.

    Science.gov (United States)

    Quirnheim Pais, David; Rathmann, Barbara; Koepke, Juergen; Tomova, Cveta; Wurzinger, Paul; Thielmann, Yvonne

    2017-12-01

    Cryogenic temperatures slow down secondary radiation damage during data collection from macromolecular crystals. In 1973, cooling at high pressure was identified as a method for cryopreserving crystals in their mother liquor [Thomanek et al. (1973). Acta Cryst. A29, 263-265]. Results from different groups studying different crystal systems indicated that the approach had merit, although difficulties in making the process work have limited its widespread use. Therefore, a simplified and reliable technique has been developed termed high-pressure cooling (HPC). An essential requirement for HPC is to protect crystals in capillaries. These capillaries form part of new sample holders with SPINE standard dimensions. Crystals are harvested with the capillary, cooled at high pressure (220 MPa) and stored in a cryovial. This system also allows the usage of the standard automation at the synchrotron. Crystals of hen egg-white lysozyme and concanavalin A have been successfully cryopreserved and yielded data sets to resolutions of 1.45 and 1.35 Å, respectively. Extensive work has been performed to define the useful working range of HPC in capillaries with 250 µm inner diameter. Three different 96-well crystallization screens that are most frequently used in our crystallization facility were chosen to study the formation of amorphous ice in this cooling setup. More than 89% of the screening solutions were directly suitable for HPC. This achievement represents a drastic improvement for crystals that suffered from cryoprotection or were not previously eligible for cryoprotection.

  12. Enhancement of heat transfer in Czochralski growth of silicon crystals with a chemical cooling technique

    Science.gov (United States)

    Ding, Junling; Liu, Lijun; Zhao, Wenhan

    2017-06-01

    The cost of producing single-crystalline silicon with the Czochralski method can be reduced by promoting the crystal size and/or crystal pulling rate. However, more latent heat of solidification needs to be released from the melt-crystal (m-c) interface during the crystal growth process. In this study, the C-CO2 chemical endothermic reaction is proposed as a novel and efficient cooling technique to solve this problem. Compared with the conventional gas cooling method, C-CO2 endothermic reaction method can significantly enhance the heat transfer in the crystal at the m-c interface. It was found that the heat transfer is more enhanced with a chemical reaction of smaller activation energy, and the m-c interface becomes flatter. The influence of the carbon concentration in the chemical reactive gas flow on the heat removal in the crystal at the m-c interface is also investigated. The cooling effect is significantly increased with the increase in the carbon concentration when it is small. However, when the carbon concentration in the reactive gas is high, the cooling effect just increases slightly. The research demonstrates that the proposed chemical endothermic reaction is a promising cooling technique to be applied in CZ-Si crystal growth with large size/high pulling rate.

  13. A growing toolbox of techniques for studying β-barrel outer membrane protein folding and biogenesis.

    Science.gov (United States)

    Horne, Jim E; Radford, Sheena E

    2016-06-15

    Great strides into understanding protein folding have been made since the seminal work of Anfinsen over 40 years ago, but progress in the study of membrane protein folding has lagged behind that of their water soluble counterparts. Researchers in these fields continue to turn to more advanced techniques such as NMR, mass spectrometry, molecular dynamics (MD) and single molecule methods to interrogate how proteins fold. Our understanding of β-barrel outer membrane protein (OMP) folding has benefited from these advances in the last decade. This class of proteins must traverse the periplasm and then insert into an asymmetric lipid membrane in the absence of a chemical energy source. In this review we discuss old, new and emerging techniques used to examine the process of OMP folding and biogenesis in vitro and describe some of the insights and new questions these techniques have revealed. © 2016 The Author(s).

  14. A Review of Domain Modelling and Domain Imaging Techniques in Ferroelectric Crystals.

    Science.gov (United States)

    Potnis, Prashant R; Tsou, Nien-Ti; Huber, John E

    2011-02-16

    The present paper reviews models of domain structure in ferroelectric crystals, thin films and bulk materials. Common crystal structures in ferroelectric materials are described and the theory of compatible domain patterns is introduced. Applications to multi-rank laminates are presented. Alternative models employing phase-field and related techniques are reviewed. The paper then presents methods of observing ferroelectric domain structure, including optical, polarized light, scanning electron microscopy, X-ray and neutron diffraction, atomic force microscopy and piezo-force microscopy. Use of more than one technique for unambiguous identification of the domain structure is also described.

  15. A Review of Domain Modelling and Domain Imaging Techniques in Ferroelectric Crystals

    Directory of Open Access Journals (Sweden)

    John E. Huber

    2011-02-01

    Full Text Available The present paper reviews models of domain structure in ferroelectric crystals, thin films and bulk materials. Common crystal structures in ferroelectric materials are described and the theory of compatible domain patterns is introduced. Applications to multi-rank laminates are presented. Alternative models employing phase-field and related techniques are reviewed. The paper then presents methods of observing ferroelectric domain structure, including optical, polarized light, scanning electron microscopy, X-ray and neutron diffraction, atomic force microscopy and piezo-force microscopy. Use of more than one technique for unambiguous identification of the domain structure is also described.

  16. Studies of Phase Transformation in Molecular Crystals Using the Positron Annihilation Technique

    DEFF Research Database (Denmark)

    Eldrup, Morten Mostgaard; Lightbody, David; Sherwood, John N.

    1980-01-01

    An examination has been made of the brittle/plastic phase transformation in the molecular crystals cyclohexane, DL-camphene and succinonitrile using the positron annihilation technique. In each material, the transition is characterized by a distinct increase in ortho-positronium lifetime. The inf......An examination has been made of the brittle/plastic phase transformation in the molecular crystals cyclohexane, DL-camphene and succinonitrile using the positron annihilation technique. In each material, the transition is characterized by a distinct increase in ortho-positronium lifetime...

  17. Effect of rearing technique in outdoor floor cage on slow growing rabbit population performance

    Directory of Open Access Journals (Sweden)

    G. Preziuso

    2010-04-01

    Full Text Available The aim of this research was to test the effect of floor cage in outdoor pen on productive performance and carcass characteristics of a rabbit local population characterized by slow growing rate. A sample of 48 rabbits female 57 days old was divided into two groups: Indoor group, housed in colony cages indoor at the density of 14 animals/m2 and Outdoor group, in wire net floor colony cages in outdoor pen, at the density of 5 animals/ m2. The animals were fed a commercial feed and ad libitum alfa-alfa hay. Individual live weight and cage feed consumption were checked every week and feed conversion ratio was calculated; at 103 ± 2 days old a sample of 24 animals was slaughtered and carcass traits were recorded. The results showed that the Outdoor group had the highest live weight and the best daily weight gain, together with an higher feed intake. Outdoor group showed the lower mortality, the higher slaughtering weight, the higher reference carcass incidence and hind leg percentage. These favourable results encouraged this kind of rearing system characterized also by lower investment costs.

  18. Theoretical study of the impact of stress and interstitial oxygen on the behavior of intrinsic point defects in growing Czochralski Si crystals

    Science.gov (United States)

    Sueoka, K.; Nakamura, K.; Vanhellemont, J.

    2017-09-01

    For the development of crystal pulling processes for 450 mm-diameter defect-free Si crystals, it is important to evaluate the impact of thermal stress on intrinsic point defect behavior during crystal growth. In a crystal growing from a melt, the melt/solid interface can be considered as being stress-free. Due to that the thermal stress in the growing substrate near the interface is internal plane stress. Previously, we evaluated the impact of (001) planar-isotropic stress on the formation enthalpy (Hf) of the vacancy (V) and the self-interstitial (I) using density functional theory (DFT) calculations, and explained quantitatively the published experimental values of the so-called ;Voronkov criterion;. The thermal stress in a growing crystal is indeed planar but is not isotropic in the plane except for the central region of the crystal. The purpose of the present study is to estimate the impact of planar-anisotropic stress on the formation enthalpy Hf of V and I. It is found that the three stress dependencies of σx: σy=1: 1 (planar-isotropic), 2: 1, 5: 1 (planar-anisotropic) are close to each other, independent of the assumption of isotropic or anisotropic planar stress. This is the reason why the experimental results obtained over the whole radial direction of the crystal are well reproduced by the calculated results assuming planar-isotropic stress. A uniaxial stress dependence which is a good assumption for the crystal peripheral region, leads also to results that are close to those for the planar stress dependence. Also the mechanisms behind the experimentally observed impact of interstitial oxygen (Oi), introduced during Czochralski Si growth, on V and I concentrations are clarified. DFT calculations are performed to obtain the formation energies (Ef) of V and I at all sites within a sphere with 5 Å radius around the Oi atom. Formation (vibration) entropy (Sf) calculations for V and I are also performed. It is found that both EfV and SfV of V in the zigzag

  19. Imaging transport phenomena during lysozyme protein crystal growth by the hanging drop technique

    Science.gov (United States)

    Sethia Gupta, Anamika; Gupta, Rajive; Panigrahi, P. K.; Muralidhar, K.

    2013-06-01

    The present study reports the transport process that occurs during the growth of lysozyme protein crystals by the hanging drop technique. A rainbow schlieren technique has been employed for imaging changes in salt concentration. A one dimensional color filter is used to record the deflection of the light beam. An optical microscope and an X-ray crystallography unit are used to characterize the size, tetragonal shape and Bravais lattice constants of the grown crystals. A parametric study on the effect of drop composition, drop size, reservoir height and number of drops on the crystal size and quality is reported. Changes in refractive index are not large enough to create a meaningful schlieren image in the air gap between the drop and the reservoir. However, condensation of fresh water over the reservoir solution creates large changes in the concentration of NaCl, giving rise to clear color patterns in the schlieren images. These have been analyzed to obtain salt concentration profiles near the free surface of the reservoir solution as a function of time. The diffusion of fresh water into the reservoir solution at the early stages of crystal growth followed by the mass flux of salt from the bulk solution towards the free surface has been recorded. The overall crystal growth process can be classified into two regimes, as demarcated by the changes in slope of salt concentration within the reservoir. The salt concentration in the reservoir equilibrates at long times when the crystallization process is complete. Thus, transport processes in the reservoir emerge as the route to monitor protein crystal growth in the hanging drop configuration. Results show that crystal growth rate is faster for a higher lysozyme concentration, smaller drops, and larger reservoir heights.

  20. Long-life tomato cultivars growing under the hydroponic Nutrient Film Technique

    Directory of Open Access Journals (Sweden)

    Gualberto Ronan

    2002-01-01

    Full Text Available Farmers are interested in hydroponic tomato cultivation because of the high demand of high quality products by the consumers. Three trials here carried out under greenhouse conditions in Marília, SP, Brazil, using the hydroponic nutrient film technique, in order to evaluate yield and quality of long-life salad tomato (Lycopersicon esculentum varieties, during 1998 and 1999. Four varieties (Carmen, Diva, Graziela, and Vita were tested using a randomized block design, with six replications. The variety x crop season interaction effect was significant, meaning that varieties have distinct performances during the different cropping seasons. The Vita variety presented commercial valid yield, with mean fruit weights higher than the other varieties.

  1. In Situ Determination of Thermal Profiles during Czochralski Silicon Crystal Growth by an Eddy Current Technique.

    Science.gov (United States)

    Choe, Kwang Su.

    An eddy current testing method was developed to continuously monitor crystal growth process and determine thermal profiles in situ during Czochralski silicon crystal growth. The work was motivated by the need to improve the quality of the crystal by controlling thermal gradients and annealing history over the growth cycle. The experimental concept is to monitor intrinsic electrical conductivities of the growing crystal and deduce temperature values from them. The experiments were performed in a resistance-heated Czochralski puller with a 203 mm (8 inch) diameter crucible containing 6.5 kg melt. The silicon crystals being grown were about 80 mm in diameter and monitored by an encircling sensor operating at three different test frequencies (86, 53 and 19 kHz). A one-dimensional analytical solution was employed to translate the detected signals into electrical conductivities. In terms of experiments, the effects of changes in growth condition, which is defined by crystal and crucible rotation rates, crucible position, pull rate, and hot-zone configuration, were investigated. Under a given steady-state condition, the thermal profile was usually stable over the entire length of crystal growth. The profile shifted significantly, however, when the crucible rotation rate was kept too high. As a direct evidence to the effects of melt flow on heat transfer process, a thermal gradient minimum was observed about the crystal/crucible rotation combination of 20/-10 rpm cw. The thermal gradient reduction was still most pronounced when the pull rate or the radiant heat loss to the environment was decreased: a nearly flat axial thermal gradient was achieved when either the pull rate was halved or the height of the exposed crucible wall was effectively doubled. Under these conditions, the average axial thermal gradient along the surface of the crystal was about 4-5 ^{rm o}C/mm. Regardless of growth condition, the three-frequency data revealed radial thermal gradients much larger

  2. Measuring fission lifetimes with the crystal-blocking technique in mono-crystal, access to nuclear dissipation

    International Nuclear Information System (INIS)

    Basnary, St.

    2002-10-01

    Energy dissipation in nuclear matter may play an important role in the determination of the way through which heavy nuclei des-excite: fission or particle evaporation. An important dissipation should imply longer interval of time during which the nucleus is deformed. In that way the measurement of fission lifetimes may shed light on energy dissipation, but these measurements are very delicate to perform. Most available data on deformation times come from indirect measurements combined with the use of more or less valid models. The crystal-blocking lifetime technique in mono-crystals allows the direct measurement of long fission lifetimes. This technique has been applied to different nuclei situated in the proximity of lead. We have obtained relatively high values: τ > 3.10 -19 s for both lead and uranium which implies a strong dissipation of energy. The computation of dissipation coefficients has led to the following values: β ≅ 2.10 21 /s for lead and β ≥ 6.10 21 /s for uranium (E * > 120 MeV). These results show that dissipation effects have to be taken into account in the determination of the deexcitation way. (A.C.)

  3. Neutron diffraction tomography: a unique, 3D inspection technique for crystals using an intensifier TV system

    International Nuclear Information System (INIS)

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

    1978-01-01

    The application of phosphor-intensifier-TV techniques to neutron topography and tomography of crystals is described. The older, analogous x-ray topography using wavelengths approximately 1.5A is widely used for surface inspection. However, the crystal must actually be cut in order to see diffraction anomalies beneath the surface. Because 1.5-A thermal neutrons are highly penetrating, much larger and thicker specimens can be used. Also, since neutrons have magnetic moments, they are diffracted by magnetic structures within crystals. In neutron volume topography, the entire crystal or a large part of it is irradiated, and the images obtained are superimposed reflections from the total volume. In neutron tomography (or section topography), a collimated beam irradiates a slice (0.5 to 10 mm) of the crystal. The diffracted image is a tomogram from this part only. A series of tomograms covering the crystal can be taken as the specimen is translated in steps across the narrow beam. Grains, voids, twinning, and other defects from regions down to 1 mm in size can be observed and isolated. Although at present poorer in resolution than the original neutron and film methods, the TV techniques are much faster and, in some cases, permit real-time viewing. Two camera systems are described: a counting camera having a 150 mm 6 Li-ZnS screen for low-intensity reflections which are integrated in a digital memory, and a 300-mm system using analog image storage. Topographs and tomograms of several crystals ranging in size from 4 mm to 80 mm are shown

  4. Thin film growing by the laser ablation technique: possibilities for growing of dosimetric materials; Crecimiento de capas delgadas por la tecnica de ablacion laser: posibilidades para crecimiento de materiales dosimetricos

    Energy Technology Data Exchange (ETDEWEB)

    Rojas R, E.M.; Melo M, M.; Enriquez Z, E.; Fernandez G, M.; Haro P, E.; Hernandez P, J.L. [UAM-I, Laboratorio de Optica Cuantica, 09340 Mexico D.F. (Mexico)

    2005-07-01

    In this talk we will present the basics about the laser ablation technique and how it is used for thin film growing, either as a single film or a stack of thin films, as well as some methods to characterize in real time the film thickness. Finally, we will discuss the possibilities of using laser ablation for growing thin films with applications to dosimetry. (Author)

  5. Environmentally friendly method to grow wide-bandgap semiconductor aluminum nitride crystals: Elementary source vapor phase epitaxy.

    Science.gov (United States)

    Wu, PeiTsen; Funato, Mitsuru; Kawakami, Yoichi

    2015-11-30

    Aluminum nitride (AlN) has attracted increasing interest as an optoelectronic material in the deep ultraviolet spectral range due to its wide bandgap of 6.0 eV (207 nm wavelength) at room temperature. Because AlN bulk single crystals are ideal device substrates for such applications, the crystal growth of bulky AlN has been extensively studied. Two growth methods seem especially promising: hydride vapor phase epitaxy (HVPE) and sublimation. However, the former requires hazardous gases such as hydrochloric acid and ammonia, while the latter needs extremely high growth temperatures around 2000 °C. Herein we propose a novel vapor-phase-epitaxy-based growth method for AlN that does not use toxic materials; the source precursors are elementary aluminum and nitrogen gas. To prepare our AlN, we constructed a new growth apparatus, which realizes growth of AlN single crystals at a rate of ~18 μm/h at 1550 °C using argon as the source transfer via the simple reaction Al + 1/2N2 → AlN. This growth rate is comparable to that by HVPE, and the growth temperature is much lower than that in sublimation. Thus, this study opens up a novel route to achieve environmentally friendly growth of AlN.

  6. Environmentally friendly method to grow wide-bandgap semiconductor aluminum nitride crystals: Elementary source vapor phase epitaxy

    Science.gov (United States)

    Wu, Peitsen; Funato, Mitsuru; Kawakami, Yoichi

    2015-11-01

    Aluminum nitride (AlN) has attracted increasing interest as an optoelectronic material in the deep ultraviolet spectral range due to its wide bandgap of 6.0 eV (207 nm wavelength) at room temperature. Because AlN bulk single crystals are ideal device substrates for such applications, the crystal growth of bulky AlN has been extensively studied. Two growth methods seem especially promising: hydride vapor phase epitaxy (HVPE) and sublimation. However, the former requires hazardous gases such as hydrochloric acid and ammonia, while the latter needs extremely high growth temperatures around 2000 °C. Herein we propose a novel vapor-phase-epitaxy-based growth method for AlN that does not use toxic materials; the source precursors are elementary aluminum and nitrogen gas. To prepare our AlN, we constructed a new growth apparatus, which realizes growth of AlN single crystals at a rate of ~18 μm/h at 1550 °C using argon as the source transfer via the simple reaction Al + 1/2N2 → AlN. This growth rate is comparable to that by HVPE, and the growth temperature is much lower than that in sublimation. Thus, this study opens up a novel route to achieve environmentally friendly growth of AlN.

  7. Infrared spectroscopic study on polytypic transformation of growing single crystal of n-hexatriacontane ( n-C 36H 74)

    Science.gov (United States)

    Kubota, Hideki; Kaneko, Fumitoshi; Kawaguchi, Tatsuya; Kawasaki, Masatsugu

    2005-02-01

    There are two polytypic structures, single-layered structure Mon and double-layered structure Orth II for the M 011 modification of n-hexatriacontane ( n-C 36H 74). The solution crystal growth of the two polytypes under controlled supersaturation was investigated by the oblique IR transmission method. As to the supersaturation dependence of growth behavior, there was a significant difference between the two polytypes. While the overgrowth of Orth II took place on the (0 0 1) face of the Mon crystal at moderate supersaturations, the overgrowth of Mon on the Orth II crystals was not confirmed at any supersaturations below 0.30. The growth rate of Mon showed about a second-order dependence on supersaturation, whereas that of Orth II showed a first-order dependence. The growth mechanism of the M 011 modification and the cause for the one-way overgrowth were deduced on the basis of the thermodynamical stabilities and the supersaturation dependence of the growth rates.

  8. Determination of phase transitions in a lyotropic liquid crystal by Positron Annihilation technique

    International Nuclear Information System (INIS)

    Castillo V, V.M.

    1994-01-01

    Positron annihilation technique was used to determine the phase transitions in a lyotropic liquid crystal, as a function of temperature. Seven different concentrations of the surfactant cetyldimethylethylammonium bromide, were studied. The liquid crystal studied consisted of a binary system, formed by the surfactant and water. Positron annihilation technique has a very high sensitivity toward changes in the microestructure, in condensed matter, this is useful in order to detect the temperatures at which phase transitions occur and the number of these, in a liquid crystalline system. Thus, phase transitions are related with changes occurred in the ortho-positronium parameters: lifetime (τ 3 ) and intensity of formation (I 3 ). Six different kinds of phases were detected in the system studied in a temperature range of 35 to 140 Centigrade degrees, those phases were: hexagonal, hexagonal-lamellae, lamellae, lamellae-cubic, nematic and anisotropic. Using optical microscopic the textures of these phases were assigned. (Author)

  9. One-stage posterior osteotomy with short segmental fusion and dual growing rod technique for severe rigid congenital scoliosis: the preliminary clinical outcomes of a hybrid technique.

    Science.gov (United States)

    Wang, Shengru; Zhang, Jianguo; Qiu, Guixing; Wang, Yipeng; Weng, Xisheng; Guo, Jianwei

    2014-02-15

    Retrospective study. To evaluate the clinical outcomes of the hybrid technique of 1-stage posterior osteotomy with short segmental fusion and dual growing rod (GR) technique for severe rigid congenital scoliosis. As some types of congenital scoliosis consist of long curve including sharp deformities producing enormous asymmetric growth at apex, they cannot be well corrected with osteotomy and short segmental fusion. GR technique may be the best option. However, enormous asymmetric growth potential due to the sharp deformities at the apex will increase risk of complications, especially implant failures. Seven patients (2 males, 5 females) undergoing this hybrid technique for severe rigid congenital scoliosis were retrospectively reviewed. The patients' charts were reviewed. The analysis included age at initial surgery and the latest follow-up, number and frequency of lengthening, and complications. Radiographical evaluation included measured changes in scoliosis Cobb angle, thoracic kyphosis, lumbar lordosis, trunk shift, length of T1-S1, and instrumentation. The mean follow-up was 53.3 (30-77) months. The mean age at the initial surgery is 5.9 (2-10) years. The averaged lengthenings were of 5.3 per patient. The mean scoliosis improved from 81.4° to 40.1° after initial surgery and was 41.0° at the latest follow-up. The average T1-S1 length was of 1.23 cm per year. The space available for lung ratio increased from 0.86 to 0.96. Osteotomy with short fusion could help to improve the correction of the GR and eliminate the large asymmetric growth potential around the apex, with little influence to the length of the spine. Dual GR technique could maintain correction achieved at initial surgery while allowing spinal growth to continue. This hybrid technique may be an option for young patients who present sharp deformities with large asymmetric growth potential in a long congenital spinal deformity. 4.

  10. The feasibility of using particle-in-cell technique for modeling liquid crystal devices

    Science.gov (United States)

    Leung, Wing Ching

    1997-12-01

    Liquid crystal materials are used in a variety of electronic devices, but the dynamical behavior of such devices is still not clearly understood. The primary reason for this is that there is a lack of rigorous models for a theoretical treatment for the devices. For the first time we demonstrate here the feasibility of treating such liquid crystal devices using the particle- in-cell (PIC) simulation technique. In a PIC simulation model, the liquid crystal medium is represented by a certain number of particles, each particle representing a fairly large number of real molecules in the medium. The dynamical behavior of the medium is obtained by solving the equations of motions of the particles in self- consistent appropriate fields. The motions may include both translation (flow) and rotation. By neglecting the translational motion and the conductive effects of the materials in this first innovative effort, 1- and 2- dimensional PIC codes, including viscous, electric, and elastic torques affecting the rotation of molecules, are developed for modeling a parallel-plate capacitor cell filled with a nematic liquid crystal material. Using these codes we reproduce the well known phenomenon of Fredericksz transition. Our simulations yield results in excellent agreement with the available analytical results on the threshold voltage for the Fredericksz transition. In addition, we are able to reveal the dynamical behavior of liquid crystal molecules in the device as the material undergoes the Fredericksz transition in response to an applied voltage across the liquid crystal cell. By using the 2-dimensional PIC code to simulate a segmented electrode cell, like those used in liquid crystal devices for optical gratings, the simulation results show the formation and dynamics of the defect walls. The defect wall joins the regions of the material having topologically different orientations. We found that the defect wall is associated with a large gradient in the polarization vector P

  11. 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.

  12. A comparison of the techniques for the study of molecular motion in crystals

    International Nuclear Information System (INIS)

    Powles, J.G.

    1976-01-01

    An informal review is presented of the nature of molecular motion in molecular crystals. Particular attention is paid to the various methods of experimental measurement, especially with regard to the actual information about molecular motion which can be obtained and to the 'selectivity' of the different techniques. The latter include: self-diffusion by tracer and nuclear spin relaxation in a field gradient; dielectric and infra-red absorption; slow-neutron sacttering; Rayleigh and Raman scattering; nuclear magnetic spin relaxation; and computer simulation techniques. (orig.) [de

  13. Development of n- and p-type Doped Perovskite Single Crystals Using Solid-State Single Crystal Growth (SSCG) Technique

    Science.gov (United States)

    2017-10-09

    tried. Among them “n- and p-type doped” BaTiO3 single crystals have been successfully fabricated . And their bi- crystals containing a twin or twist...boundary are also fabricated using diffusion bonding process of two single crystal plates. These results demonstrate that the SSCG (solid-state...or Bridgman method have critical limitations; high production cost and compositional inhomogeneity throughout the crystal. These limitations result

  14. Measurements of processes in ruthenium oxide film electrodes with the quartz-crystal microbalance technique

    International Nuclear Information System (INIS)

    Buttry, D.; Gottesfeld, S.

    1987-01-01

    The authors describe the first application of the quartz-crystal microbalance (QCM) technique for monitoring electrochemical processes in oxide film electrodes. They have investigated a film of ruthenium oxide, applied by the thermal decomposition of ruthenium chloride onto one side of the quartz-crystal. The quartz-crystal was precoated with gold keyhole patterns on both sides for inducing the 5 MHz resonance, followed by a thin Ti layer to ensure good adherence of the ruthenium oxide. Ruthenium oxide films are being investigated at Los Alamos for potential use in electrochemical capacitors. The material exhibits large charge capacity per geometric area and fast charge-discharge rates. Different possible processes can be responsible for charge compensation in such oxide materials, including those associated with simple double-layer charging, with pseudocapacitance, and with ion insertion into the small grains of the high-surface-area oxide material. The dynamics of such processes are determined, for a given oxide film, by the nature of the electrolyte and the resulting mechanism of charge-compensation. The QCM technique provides interesting information on these processes, as well as on film hydration and film dissolution process. The authors' initial results are presented in this paper. The results demonstrate the QCM as a sensitive tool for following not only ionic insertion processes during potential modulation, but also processes of film swelling and film dissolution

  15. Spherical crystallization: A technique use to reform solubility and flow property of active pharmaceutical ingredients.

    Science.gov (United States)

    Chatterjee, Arindam; Gupta, Madan Mohan; Srivastava, Birendra

    2017-01-01

    Tablets have been choice of manufacturers over the years due to their comparatively low cost of manufacturing, packaging, shipping, and ease of administration; also have better stability and can be considered virtually tamper proof. A major challenge in formulation development of the tablets extends from lower solubility of the active agent to the elaborated manufacturing procedures for obtaining a compressible granular material. Moreover, the validation and documentation increases, as the numbers of steps increases for an industrially acceptable granulation process. Spherical crystallization (SC) is a promising technique, which encompass the crystallization, agglomeration, and spheronization phenomenon in a single step. Initially, two methods, spherical agglomeration, and emulsion solvent diffusion, were suggested to get a desired result. Later on, the introduction of modified methods such as crystallo-co-agglomeration, ammonia diffusion system, and neutralization techniques overcame the limitations of the older techniques. Under controlled conditions such as solvent composition, mixing rate and temperature, spherical dense agglomerates cluster from particles. Application of the SC technique includes production of compacted spherical particles of drug having improved uniformity in shape and size of particles, good bulk density, better flow properties as well as better solubility so SC when used on commercial scale will bring down the production costs of pharmaceutical tablet and will increase revenue for the pharmaceutical industries in the competitive market. This review summarizes the technologies available for SC and also suggests the parameters for evaluation of a viable product.

  16. Macromolecular Crystallization in Microgravity

    Science.gov (United States)

    Snell, Edward H.; Helliwell, John R.

    2004-01-01

    The key concepts that attracted crystal growers, macromolecular or solid state, to microgravity research is that density difference fluid flows and sedimentation of the growing crystals are greatly reduced. Thus, defects and flaws in the crystals can be reduced, even eliminated, and crystal volume can be increased. Macromolecular crystallography differs from the field of crystalline semiconductors. For the latter, crystals are harnessed for their electrical behaviors. A crystal of a biological macromolecule is used instead for diffraction experiments (X-ray or neutron) to determine the three-dimensional structure of the macromolecule. The better the internal order of the crystal of a biological macromolecule then the more molecular structure detail that can be extracted. 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. Macromolecular structural crystallography in general is a remarkable field where physics, biology, chemistry, and mathematics meet to enable insight to the basic fundamentals of life. 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 analyze the resulting data. Several case studies illustrate the physical crystal quality improvements and the macromolecular structural

  17. Decrystallization of Crystals Using Gold “Nano-Bullets” and the Metal-Assisted and Microwave-Accelerated Decrystallization Technique

    Science.gov (United States)

    Thompson, Nishone; Boone-Kukoyi, Zainab; Shortt, Raquel; Lansiquot, Carisse; Kioko, Bridgit; Bonyi, Enock; Toker, Salih; Ozturk, Birol; Aslan, Kadir

    2017-01-01

    Gout is caused by the overproduction of uric acid and the inefficient metabolism of dietary purines in humans. Current treatments of gout, which include anti-inflammatory drugs, cyclooxygenase-2 inhibitors, and systemic glucocorticoids, have harmful side-effects. Our research laboratory has recently introduced an innovative approach for the decrystallization of biological and chemical crystals using the Metal-Assisted and Microwave-Accelerated Evaporative Decrystallization (MAMAD) technique. In the MAMAD technique, microwave energy is used to heat and activate gold nanoparticles that behave as “nano-bullets” to rapidly disrupt the crystal structure of biological crystals placed on planar surfaces. In this study, crystals of various sizes and compositions were studied as models for tophaceous gout at different stages (i.e., uric acid as small crystals (~10–100 μm) and L-alanine as medium (~300 μm) and large crystals (~4400 μm). Our results showed that the use of the MAMAD technique resulted in the reduction of the size and number of uric acid and L-alanine crystals up to >40% when exposed to intermittent microwave heating (up to 20 W power at 8 GHz) in the presence of 20 nm gold nanoparticles up to 120 s. This study demonstrates that the MAMAD technique can be potentially used as an alternative therapeutic method for the treatment of gout by effective decrystallization of large crystals, similar in size to those that often occur in gout. PMID:27763557

  18. Decrystallization of Crystals Using Gold "Nano-Bullets" and the Metal-Assisted and Microwave-Accelerated Decrystallization Technique.

    Science.gov (United States)

    Thompson, Nishone; Boone-Kukoyi, Zainab; Shortt, Raquel; Lansiquot, Carisse; Kioko, Bridgit; Bonyi, Enock; Toker, Salih; Ozturk, Birol; Aslan, Kadir

    2016-10-18

    Gout is caused by the overproduction of uric acid and the inefficient metabolism of dietary purines in humans. Current treatments of gout, which include anti-inflammatory drugs, cyclooxygenase-2 inhibitors, and systemic glucocorticoids, have harmful side-effects. Our research laboratory has recently introduced an innovative approach for the decrystallization of biological and chemical crystals using the Metal-Assisted and Microwave-Accelerated Evaporative Decrystallization (MAMAD) technique. In the MAMAD technique, microwave energy is used to heat and activate gold nanoparticles that behave as "nano-bullets" to rapidly disrupt the crystal structure of biological crystals placed on planar surfaces. In this study, crystals of various sizes and compositions were studied as models for tophaceous gout at different stages (i.e., uric acid as small crystals (~10-100 μm) and l-alanine as medium (~300 μm) and large crystals (~4400 μm). Our results showed that the use of the MAMAD technique resulted in the reduction of the size and number of uric acid and l-alanine crystals up to >40% when exposed to intermittent microwave heating (up to 20 W power at 8 GHz) in the presence of 20 nm gold nanoparticles up to 120 s. This study demonstrates that the MAMAD technique can be potentially used as an alternative therapeutic method for the treatment of gout by effective decrystallization of large crystals, similar in size to those that often occur in gout.

  19. Analysis of arbitrary defects in photonic crystals by use of the source-model technique.

    Science.gov (United States)

    Ludwig, Alon; Leviatan, Yehuda

    2004-07-01

    A novel method derived from the source-model technique is presented to solve the problem of scattering of an electromagnetic plane wave by a two-dimensional photonic crystal slab that contains an arbitrary defect (perturbation). In this method, the electromagnetic fields in the perturbed problem are expressed in terms of the field due to the periodic currents obtained from a solution of the corresponding unperturbed problem plus the field due to yet-to-be-determined correction current sources placed in the vicinity of the perturbation. Appropriate error measures are suggested, and a few representative structures are presented and analyzed to demonstrate the versatility of the proposed method and to provide physical insight into waveguiding and defect coupling mechanisms typical of finite-thickness photonic crystal slabs.

  20. Real-time holographic interferometry using photorefractive sillenite crystals with phase-stepping technique

    Science.gov (United States)

    Gesualdi, M. R. R.; Soga, D.; Muramatsu, M.

    2006-01-01

    This work presents a holographic interferometer that uses the photorefractive sillenite crystals in diffusive regimen whose configuration exhibits diffraction anisotropy for real-time holographic interferometry. The writing-reading process of holographic interferogram was done in real-time, connected with an interferogram-analysis method that uses the phase-stepping technique for quantitative measurement of changes on an object. The holographic interferograms from the analyzed surface were captured and they were used to calculate the phase map with four-frame technique. The unwrapping process used was the cellular-automata technique. We obtained quantitative results for some applications: measurements of micro-rotation of surfaces, punctual micro-displacements on an aluminum plate, stress on a dog's jaw, among others; adding new promising applications possibilities for basic research, dentistry and technological areas.

  1. The effect of posterior distraction on vertebral growth in immature pigs: an experimental simulation of growing rod technique.

    Science.gov (United States)

    Yilmaz, Güney; Huri, Gazi; Demirkran, Gökhan; Dağloğlu, Kenan; Ozkan, Cenk; Alanay, Ahmet; Acaroglu, Emre; Yazici, Muharrem

    2010-04-01

    Experimental study. The aim of this study is to evaluate the vertebral body growth under distraction forces in immature pigs treated with growing rod (GR) technique. Distraction forces applied on growth plate of appendicular skeleton stimulate longitudinal growth. However, the effect of distraction forces on axial skeletal growth has not been fully investigated yet. Twelve 10-week-old domestic pigs were used in this experimental model to simulate GR technique. Four of them were lost during postoperative period because of deep wound infection. Cranially T12-L1 and caudally L4-L5 vertebrae were instrumented by pedicle screws bilaterally, while L2 and L3 were skipped. Distraction between pedicle screws was applied at index surgery. The rods were then lengthened twice in a month interval. All subjects were evaluated with anteroposterior and lateral spinal radiograph before surgery, after surgery, and at the final follow-up. The vertebral body heights of distracted segments (HD = L2 and L3) and control segments (HC = T9, T10 and T11) were measured. Average vertebral body heights and the increase percentage in the vertebral body heights were compared among control segments and distracted segments. The preoperative vertebral body height was similar in 2 groups (preHC: 10.81 mm, n = 19, preHD: 11.27 mm, n = 16, P > 0.05). At the final follow-up, the average vertebral body height in distraction group was significantly higher than the control group (postHC: 17.03 mm, postHD: 18.58 mm, P < 0.05). The increase percentage in vertebral body height was higher in distracted segments, but there was no statistically significant difference between the 2 groups. The vertebral growth continues during GR instrumentation. Distraction forces might stimulate also apophyseal growth of axial skeleton.

  2. A study on density functional theory of the effect of pressure on the formation and migration enthalpies of intrinsic point defects in growing single crystal Si

    Science.gov (United States)

    Sueoka, Koji; Kamiyama, Eiji; Kariyazaki, Hiroaki

    2012-05-01

    In 1982, Voronkov presented a model describing point defect behavior during the growth of single crystal Si from a melt and derived an expression to predict if the crystal was vacancy- or self-interstitial-rich. Recently, Vanhellemont claimed that one should take into account the impact of compressive stress introduced by the thermal gradient at the melt/solid interface by considering the hydrostatic pressure dependence of the formation enthalpy of the intrinsic point defects. To evaluate the impact of thermal stress more correctly, the pressure dependence of both the formation enthalpy (Hf) and the migration enthalpy (Hm) of the intrinsic point defects should be taken into account. Furthermore, growing single crystal Si is not under hydrostatic pressure but almost free of external pressure (generally in Ar gas under reduced pressure). In the present paper, the dependence of Hf and Hm on the pressure P, or in other words, the pressure dependence of the formation energy (Ef) and the relaxation volume (vf), is quantified by density functional theory calculations. Although a large number of ab initio calculations of the properties of intrinsic point defects have been published during the last years, calculations for Si crystals under pressure are rather scarce. For vacancies V, the reported pressure dependences of HfV are inconsistent. In the present study, by using 216-atom supercells with a sufficient cut-off energy and mesh of k-points, the neutral I and V are found to have nearly constant formation energies EfI and EfV for pressures up to 1 GPa. For the relaxation volume, vfI is almost constant while vfV decreases linearly with increasing pressure P. In case of the hydrostatic pressure Ph, the calculated formation enthalpy HfI and migration enthalpy HmI at the [110] dumbbell site are given by HfI = 3.425 - 0.057 × Ph (eV) and HmI = 0.981 - 0.039 × Ph (eV), respectively, with Ph given in GPa. The calculated HfV and HmV dependencies on Ph given by HfV = 3.543 - 0

  3. Lectin typing of Campylobacter jejuni using a novel quartz crystal microbalance technique

    Energy Technology Data Exchange (ETDEWEB)

    Yakovleva, Maria E., E-mail: maria.yakovleva@gmail.com [Department of Infectious Diseases and Medical Microbiology, Lund University, 223 62 Lund (Sweden); Moran, Anthony P. [Department of Microbiology, School of Natural Sciences, National University of Ireland, Galway (Ireland); Safina, Gulnara R. [Department of Analytical and Marine Chemistry, University of Gothenburg, 412 96 Gothenburg (Sweden); Wadstroem, Torkel [Department of Infectious Diseases and Medical Microbiology, Lund University, 223 62 Lund (Sweden); Danielsson, Bengt [Acromed Invest AB, Magistratsvaegen 10, 226 43 Lund (Sweden)

    2011-05-23

    Seven Campylobacter jejuni strains were characterised by a lectin typing assay. The typing system was based on a quartz crystal microbalance technique (QCM) with four commercially available lectins (wheat germ agglutinin, Maackia amurensis lectin, Lens culinaris agglutinin, and Concanavalin A), which were chosen for their differing carbohydrate specificities. Initially, the gold surfaces of the quartz crystals were modified with 11-mercaptoundecanoic acid followed by lectin immobilisation using a conventional amine-coupling technique. Bacterial cells were applied for lectin typing without preliminary treatment, and resonant frequency and dissipation responses were recorded. The adhesion of microorganisms on lectin surfaces was confirmed by atomic force microscopy. Scanning was performed in the tapping mode and the presence of bacteria on lectin-coated surfaces was successfully demonstrated. A significant difference in the dissipation response was observed for different C. jejuni strains which made it possible to use this parameter for discriminating between bacterial strains. In summary, the QCM technique proved a powerful tool for the recognition and discrimination of C. jejuni strains. The approach may also prove applicable to strain discrimination of other bacterial species, particularly pathogens.

  4. Lectin typing of Campylobacter jejuni using a novel quartz crystal microbalance technique

    International Nuclear Information System (INIS)

    Yakovleva, Maria E.; Moran, Anthony P.; Safina, Gulnara R.; Wadstroem, Torkel; Danielsson, Bengt

    2011-01-01

    Seven Campylobacter jejuni strains were characterised by a lectin typing assay. The typing system was based on a quartz crystal microbalance technique (QCM) with four commercially available lectins (wheat germ agglutinin, Maackia amurensis lectin, Lens culinaris agglutinin, and Concanavalin A), which were chosen for their differing carbohydrate specificities. Initially, the gold surfaces of the quartz crystals were modified with 11-mercaptoundecanoic acid followed by lectin immobilisation using a conventional amine-coupling technique. Bacterial cells were applied for lectin typing without preliminary treatment, and resonant frequency and dissipation responses were recorded. The adhesion of microorganisms on lectin surfaces was confirmed by atomic force microscopy. Scanning was performed in the tapping mode and the presence of bacteria on lectin-coated surfaces was successfully demonstrated. A significant difference in the dissipation response was observed for different C. jejuni strains which made it possible to use this parameter for discriminating between bacterial strains. In summary, the QCM technique proved a powerful tool for the recognition and discrimination of C. jejuni strains. The approach may also prove applicable to strain discrimination of other bacterial species, particularly pathogens.

  5. 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.

  6. A Phase Field Technique for Modeling and Predicting Flow Induced Crystallization Morphology of Semi-Crystalline Polymers

    Directory of Open Access Journals (Sweden)

    Xiaodong Wang

    2016-06-01

    Full Text Available Flow induced crystallization of semi-crystalline polymers is an important issue in polymer science and engineering because the changes in morphology strongly affect the properties of polymer materials. In this study, a phase field technique considering polymer characteristics was established for modeling and predicting the resulting morphologies. The considered crystallization process can be divided into two stages, which are nucleation upon the flow induced structures and subsequent crystal growth after the cessation of flow. Accordingly, the proposed technique consists of two parts which are a flow induced nucleation model based on the calculated information of molecular orientation and stretch, and a phase field crystal growth model upon the oriented nuclei. Two-dimensional simulations are carried out to predict the crystallization morphology of isotactic polystyrene under an injection molding process. The results of these simulations demonstrate that flow affects crystallization morphology mainly by producing oriented nuclei. Specifically, the typical skin-core structures along the thickness direction can be successfully predicted. More importantly, the results reveal that flow plays a dominant part in generating oriented crystal morphologies compared to other parameters, such as anisotropy strength, crystallization temperature, and physical noise.

  7. Crystallization Behavior of Isotactic Propylene-1-Hexene Random Copolymer Investigated by Time-Resolved SAXS/WAXD Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Y.; Zuo, F; Keum, J; Hsiao, B; Thurman, D; Tsou, A

    2010-01-01

    The crystallization behavior of isotactic propylene-1-hexene (PH) random copolymer having 5.7% mole fraction of hexene content was investigated using simultaneous time-resolved small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) techniques. For this copolymer, the hexene component cannot be incorporated into the unit cell structure of isotactic polypropylene (iPP). Only {alpha}-phase crystal form of iPP was observed when samples were melt crystallized at temperatures of 40 C, 60 C, 80 C, and 100 C. Comprehensive analysis of SAXS and WAXD profiles indicated that the crystalline morphology is correlated with crystallization temperature. At high temperatures (e.g., 100 C) the dominant morphology is the lamellar structure; while at low temperatures (e.g., 40 C) only highly disordered small crystal blocks can be formed. These morphologies are kinetically controlled. Under a small degree of supercooling (the corresponding iPP crystallization rate is slow), a segmental segregation between iPP and hexene components probably takes place, leading to the formation of iPP lamellar crystals with a higher degree of order. In contrast, under a large degree of supercooling (the corresponding iPP crystallization rate is fast), defective small crystal blocks are favored due to the large thermodynamic driving force and low chain mobility.

  8. Growth of high quality bulk size single crystals of inverted solubility lithium sulphate monohydrate

    Energy Technology Data Exchange (ETDEWEB)

    Silambarasan, A.; Rajesh, P., E-mail: rajeshp@ssn.edu.in; Ramasamy, P. [Center for Crystal Growth, SSN College of Engineering, Kalavakkam-603110 (India)

    2015-06-24

    The paper summarizes the processes of growing large lithium sulfate monohydrate (LSMH) single crystals. We have established a procedure to grow high quality bulk size single crystals of inverted solubility LSMH by a newly developed unidirectional crystallization technique called the Sankeranarayenan - Ramasamy (SR) method. The convective flow of crystal growth processes from solution and the conditions of growing crystals of various aspects were discussed. Good quality LSMH single crystal is grown of the size 20 mmX80 mm without cracks, localized-defects and inclusions. The as-grown crystals are suitable for piezoelectric and nonlinear optical applications.

  9. 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

  10. Studying the Crystallization of Various Polymorphic Forms of Nifedipine from Binary Mixtures with the Use of Different Experimental Techniques.

    Science.gov (United States)

    Madejczyk, O; Kaminska, E; Tarnacka, M; Dulski, M; Jurkiewicz, K; Kaminski, K; Paluch, M

    2017-06-05

    In this paper the crystal growth of nifedipine from pure system and from binary mixtures composed of active substance (API) and two acetylated disaccharides, maltose and sucrose (NIF-acMAL, NIF-acSUC, 5:1 weight ratio), was investigated. Optical snapshots supported by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) measurements showed that mainly β and α forms of nifedipine grow up in all investigated samples. They also revealed that the morphology of growing crystals strongly depends on the presence of modified carbohydrates and temperature conditions. Interestingly, it was found that the activation barrier for the crystal growth of the β polymorph is not affected by acetylated saccharides while the one estimated for the α form changes significantly from 48.5 kJ/mol (pure API) up to 122 kJ/mol (NIF-acMAL system). Moreover, the relationship between the crystal growth rate and structural relaxation times for pure NIF and solid dispersions were analyzed. It turned out that there is a clear decoupling between the crystal growth rate and structural dynamics in both NIF-acMAL and NIF-acSUC binary mixtures. This is in line with recent reports indicating the decoupling phenomenon to be a universal feature of soft matter in the close vicinity of the glass transition temperature.

  11. Relation between anchorings of liquid crystals and conformation changes in aligning agents by the Langmuir-Blodgett film technique investigation

    International Nuclear Information System (INIS)

    Zhu, Y.; Lu, Z.; Wei, Y.

    1995-01-01

    The anchoring direction of liquid crystals on a solid substrate surface depends upon many parameters characterizing the liquid-crystal--substrate interface, a variation of which may change this anchoring direction leading to the so-called anchoring transition. Here, based on the Langmuir-Blodgett film technique, we present two model systems to study the relation between anchoring directions and the conformation changes in aligning agents. A double-armed crown ether liquid crystal and a side chain polymer liquid crystal at an air-water interface both show phase transitions, accompanied by conformation changes. However, when the monolayers in different phases were transferred onto solid substrates to orient liquid crystals, we found that for the crown ether material the conformation change can alter the anchoring of liquid crystals between homeotropic and homogeneous alignments, while for the polymer liquid crystal, despite the conformation changes, the liquid crystals can only be aligned homeotropically. The involved mechanisms were briefly discussed in terms of the Landau-type phenomenological theory

  12. Full analysis of feldspar texture and crystal structure by combining X-ray and electron techniques

    DEFF Research Database (Denmark)

    Balic Zunic, Tonci; Piazolo, Sandra; Katerinopoulou, Anna

    2013-01-01

    Feldspar crystals typically show a range of exsolution and polysynthetic twinning textures that can present problems for their full characterization, but at the same time give important information about their genesis. We present an integrated procedure for the micro-texture analysis, twin law......-temperature (HT) feldspars had similar global chemical compositions but underwent significantly different cooling histories, with cooling times probably differing by over an order of magnitude. Powder X-ray diffraction with Rietveld refinement was used for a preliminary identification of the mineral components...... a simultaneous calculation for structurally different components. Combined results of various methods helped improve accuracy and resolve ambiguities that arise from the application of a single technique. The approach is widely applicable to the study of mineral intergrowths and bridges an existing gap...

  13. Fetal bovine serum adsorption onto hydroxyapatite sensor monitoring by quartz crystal microbalance with dissipation technique

    Energy Technology Data Exchange (ETDEWEB)

    Tagaya, Motohiro [Biomaterials Center, National Institute for Materials Science, Sengen 1-2-1, Tsukuba, Ibaraki 305-0047 (Japan); Graduate School of Science and Engineering, Tokyo Institute of Technology, O-okayama 2-12-1, Meguro-ku, Tokyo 152-8550 (Japan); Ikoma, Toshiyuki, E-mail: IKOMA.Toshiyuki@nims.go.jp [Biomaterials Center, National Institute for Materials Science, Sengen 1-2-1, Tsukuba, Ibaraki 305-0047 (Japan); Migita, Satoshi; Okuda, Mitsuhiro; Takemura, Taro; Hanagata, Nobutaka [Biomaterials Center, National Institute for Materials Science, Sengen 1-2-1, Tsukuba, Ibaraki 305-0047 (Japan); Yoshioka, Tomohiko; Tanaka, Junzo [Graduate School of Science and Engineering, Tokyo Institute of Technology, O-okayama 2-12-1, Meguro-ku, Tokyo 152-8550 (Japan)

    2010-10-15

    Adsorption behavior of fetal bovine serum (FBS) onto hydroxyapatite (HAp) was analyzed in situ in phosphate buffer saline (PBS), minimum essential mediums ({alpha}MEM or DMEM), and different carbonate-concentrated buffers by using a quartz crystal microbalance with dissipation (QCM-D) technique. Although the adsorption behaviors of FBS onto gold showed no dependence on the solvents, those onto HAp clearly depended on the adsorbed ions in the solvents (PBS or MEMs). The amount and viscoelasticity of FBS adsorbed onto HAp in PBS were approximately two times larger than those in MEMs. The adsorption amounts of carbonate ions on HAp in the carbonate buffers increased with increasing carbonate concentrations, which inhibited the adsorption of FBS and decreased the viscoelastic property of the adsorption layers.

  14. Electron and Light Microscopy Techniques Suitable for Studying Fatigue Damage in a Crystallized Glass Ceramic

    Science.gov (United States)

    Harrell, Shelley; Zaretsky, Erwin V.

    1961-01-01

    The crystals of Pyroceram are randomly oriented and highly reflective so that standard microscopy techniques are not satisfactory for studying this material. Standard replicating procedures proved difficult to use. New microscopy techniques and procedures have therefore been developed. A method for locating, orienting, and identifying specific areas to be viewed with an electron microscope is described. This method not require any special equipment. Plastic replicas were found to be unsatisfactory because of their tendency to adhere to Pryoceram. This caused them to tear when released or resulted in artifacts. Preshadowed silicon monoxide replicas were satisfactory but required a releasing agent. A method of depositing the releasing agent is described. To polish specimens without evidence of fire-polishing, it was found necessary to use a vibratory polishing technique. Chrome oxide was used as the abrasive and either water or kerosene as the lubricant. Vibratory polishing is extremely slow, but surfaces so polished show no evidence of fire polishing, even when examined by electron microscopy. The most satisfactory etching process used for Pyroceram 9608 consisted of a primary etch of 5 milliliters of hydrochloric acid (concentrated), 5 milliliters of hydrogen fluoride (45 percent), and 45 milliliters of water, and a secondary etch with methyl alcohol replacing the water. Best results were obtained with total etching times from 25 to 30 seconds. Staining of the Pyroceram surface with a Sanford's marker was found to be an expedient way to reduce the glare of reflected light.

  15. Control of interface shape during high melting sesquioxide crystal growth by HEM technique

    Science.gov (United States)

    Hu, Kaiwei; Zheng, Lili; Zhang, Hui

    2018-02-01

    During crystal growth in heat exchanger method (HEM) system, the shape of the growth interface changes with the proceeding of the growth process, which limits the crystal size and reduces the quality of the crystal. In this paper, a modified HEM system is proposed to control the interface shape for growth of sesquioxide crystals. Numerical simulation is performed to predict heat transfer, melt flow and interface shape during growth of high melting sesquioxide crystals by the heat exchanger method. The results show that a flat or slightly convex interface shape is beneficial to reduce the solute pileup in front of the melt/crystal interface and decrease the radial temperature gradient inside the crystal during growth of sesquioxide crystals. The interface shape can be controlled by adjusting the gap size d and lower resistance heater power during growth. The growth rate and the melt/crystal interface position can be obtained by two measured temperatures.

  16. Error analysis of compensation cutting technique for wavefront error of KH2PO4 crystal.

    Science.gov (United States)

    Tie, Guipeng; Dai, Yifan; Guan, Chaoliang; Zhu, Dengchao; Song, Bing

    2013-09-20

    Considering the wavefront error of KH(2)PO(4) (KDP) crystal is difficult to control through face fly cutting process because of surface shape deformation during vacuum suction, an error compensation technique based on a spiral turning method is put forward. An in situ measurement device is applied to measure the deformed surface shape after vacuum suction, and the initial surface figure error, which is obtained off-line, is added to the in situ surface shape to obtain the final surface figure to be compensated. Then a three-axis servo technique is utilized to cut the final surface shape. In traditional cutting processes, in addition to common error sources such as the error in the straightness of guide ways, spindle rotation error, and error caused by ambient environment variance, three other errors, the in situ measurement error, position deviation error, and servo-following error, are the main sources affecting compensation accuracy. This paper discusses the effect of these three errors on compensation accuracy and provides strategies to improve the final surface quality. Experimental verification was carried out on one piece of KDP crystal with the size of Φ270 mm×11 mm. After one compensation process, the peak-to-valley value of the transmitted wavefront error dropped from 1.9λ (λ=632.8 nm) to approximately 1/3λ, and the mid-spatial-frequency error does not become worse when the frequency of the cutting tool trajectory is controlled by use of a low-pass filter.

  17. Johrei, a Japanese healing technique, enhances the growth of sucrose crystals.

    Science.gov (United States)

    Teixeira, Pedro Celso Nogueira; Rocha, Humberto; Coelho Neto, José Aguiar

    2010-01-01

    The effect of Johrei treatment on the crystallization of sucrose from supersaturated solutions was studied in comparison with the crystallization in untreated solutions. This work was performed assuming that Johrei enhances the natural mechanisms of equilibrium restoration in biological and nonbiological systems. The crystallization in Johrei-treated solutions as judged by statistical analysis was found to be faster than the crystallization in untreated solutions. A discussion is presented about the mechanisms possibly involved. Copyright 2010 Elsevier Inc. All rights reserved.

  18. Low temperature three-dimensional thermoluminescence spectra of undoped YVO{sub 4} single crystals grown by different techniques

    Energy Technology Data Exchange (ETDEWEB)

    Erdei, S. [Materials Research Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Kovacs, L. [Research Laboratory for Crystal Physics, Hungarian Academy of Sciences, P.O. Box 132, H-1502 Budapest (Hungary)]|[School of Mathematical and Physical Sciences, University of Sussex, Brighton BN1 9QH (United Kingdom); Peto, A. [Institute of Isotopes, Hungarian Academy of Sciences, P.O. Box 77, H-1525 Budapest (Hungary)]|[School of Mathematical and Physical Sciences, University of Sussex, Brighton BN1 9QH (United Kingdom); Vandlik, J. [Research Institute of Materials Sciences, Hungarian Academy of Sciences, P.O. Box 49, Budapest (Hungary); Townsend, P.D. [School of Mathematical and Physical Sciences, University of Sussex, Brighton BN1 9QH (United Kingdom); Ainger, F.W. [Materials Research Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    1997-09-01

    Three dimensional (3D) thermoluminescence (TL) spectra of two yttrium orthovanadate (YVO{sub 4}) single crystals grown from YVO{sub 4} melt by the Czochralski (CZ) technique and one additional YVO{sub 4} crystal pulled from lithium-metavanadate (LiVO{sub 3}) flux by the top seeded solution growth (TSSG) method were investigated after x-ray irradiation. The TL spectra were recorded in the 200{endash}800 nm wavelength and 20{endash}300 K temperature ranges before and after annealing of the crystals in an oxygen atmosphere. In spite of the different growth conditions the measured 3D TL spectra of the CZ samples show similar TL characteristics. The main TL emission appears around 450 nm, and between 200 and 250 K. Further weak emissions were also detected at 570, 600, 650, and 710 nm wavelengths, which might be attributed to unwanted impurities. The TL spectrum of the TSSG crystal markedly differs from that of the CZ crystals. On one hand the major TL appears at lower temperatures whereas on the other hand the emission spectrum exhibits a broader band around 500 nm, while the weak bands between 500 and 700 nm could not be detected. Based on these observations the different defect structures in YVO{sub 4} crystals are discussed in the article emphasizing that 3D TL measurement is a useful practical tool for the characterization and identification of YVO{sub 4} crystals grown by different methods. {copyright} {ital 1997 American Institute of Physics.}

  19. Creep lifing methodologies applied to a single crystal superalloy by use of small scale test techniques

    Energy Technology Data Exchange (ETDEWEB)

    Jeffs, S.P., E-mail: s.p.jeffs@swansea.ac.uk [Institute of Structural Materials, Swansea University, Singleton Park SA2 8PP (United Kingdom); Lancaster, R.J. [Institute of Structural Materials, Swansea University, Singleton Park SA2 8PP (United Kingdom); Garcia, T.E. [IUTA (University Institute of Industrial Technology of Asturias), University of Oviedo, Edificio Departamental Oeste 7.1.17, Campus Universitario, 33203 Gijón (Spain)

    2015-06-11

    In recent years, advances in creep data interpretation have been achieved either by modified Monkman–Grant relationships or through the more contemporary Wilshire equations, which offer the opportunity of predicting long term behaviour extrapolated from short term results. Long term lifing techniques prove extremely useful in creep dominated applications, such as in the power generation industry and in particular nuclear where large static loads are applied, equally a reduction in lead time for new alloy implementation within the industry is critical. The latter requirement brings about the utilisation of the small punch (SP) creep test, a widely recognised approach for obtaining useful mechanical property information from limited material volumes, as is typically the case with novel alloy development and for any in-situ mechanical testing that may be required. The ability to correlate SP creep results with uniaxial data is vital when considering the benefits of the technique. As such an equation has been developed, known as the k{sub SP} method, which has been proven to be an effective tool across several material systems. The current work now explores the application of the aforementioned empirical approaches to correlate small punch creep data obtained on a single crystal superalloy over a range of elevated temperatures. Finite element modelling through ABAQUS software based on the uniaxial creep data has also been implemented to characterise the SP deformation and help corroborate the experimental results.

  20. The effect of radiation damage on optical and scintillation properties of BGO crystals grown by the LTG Cz technique

    CERN Document Server

    Gusev, V A; Kupriyanov, I N; Kuznecov, G N; Shlegel, V N; Antsygin, V D; Vasiliev, Y V

    2002-01-01

    BGO crystals grown by the low-thermal-gradient Czochralski technique (LTG Cz) exhibit two distinct types of behavior upon radiation damage and recovery. The crystals termed as of L-type remain colorless after gamma-radiation doses as high as 10 Mrad. As the irradiation dose increases the scintillation light output shows a weak monotonous degradation to 15-25%, saturating at around several hundreds krad doses. The crystals termed as of N-type attain yellow coloration after irradiation. The light output drops abruptly for 35-50% as early as after 1 krad and does not change further on. The present work is devoted to the study of radiation damage effects, self-recovery, optically stimulated recovery and thermo-stimulated current in the L- and N-type BGO crystals produced by LTG Cz.

  1. The Feasibility of Bulk Crystallization as an Industrial Purification and Production Technique for Proteins

    Science.gov (United States)

    Judge, Russell A.; Forsythe, Elizabeth L.; Johns, Michael R.; Pusey, Marc L.; White, Edward T.

    1998-01-01

    Bulk crystallization in stirred vessels is used industrially for the recovery and purification of many inorganic and organic materials. Although much has been written on the crystallization of proteins for X-ray diffraction analysis, very little has been reported on the application of bulk crystallization in stirred vessels. In this study, a 1-liter, seeded, stirred, batch crystallizer was used with ovalbumin as a model protein to test the feasibility of this crystallization method as a recovery and purification process for proteins. Results were obtained for ovalbumin solubility, nucleation thresholds, crystal breakage and crystal growth kinetics in bulk solution under a range of operating conditions of pH and ammonium sulphate concentration (Judge et al., 1996). Experiments were also performed to determine the degree of purification that can be achieved by the crystallization of ovalbumin from a mixture of proteins. The effect of the presence of these proteins upon the ovalbumin crystal growth kinetics was also investigated (Judge et al., 1995). All of these aspects are essential for the design of bulk crystallization processes which have not previously been reported for proteins. Results from a second study that investigated the effect of structurally different proteins on the solubility, crystal growth rates and crystal purity of chicken egg white lysozyme are also presented (Judge et al., 1997). In this case face growth rates were measured using lysozyme purified by liquid chromatography and the effect of the addition of specific protein impurities were observed on the (110) and (101) crystal faces. In these two studies the results are presented to show the feasibility and purifying ability of crystallization as a production process for proteins.

  2. Liquid crystal modified photonic crystal fiber (LC-PCF) fabricated with an un-cured SU-8 photoresist sealing technique for electrical flux measurement.

    Science.gov (United States)

    Kuo, Shu-Ming; Huang, Yu-Wen; Yeh, Szu-Ming; Cheng, Wood-Hi; Lin, Che-Hsin

    2011-09-12

    The optical transmission properties of photonic crystal fibers (PCFs) can be manipulated by modifying the pattern arrangement of the air channels within them. This paper presents a novel MEMS-based technique for modifying the optical transmission properties of commercial photonic-crystal fiber (PCF) by selectively filling the voids within the fiber structure with liquid crystals. In the proposed approach, an un-cured SU-8 ring pattern with a thickness of 5 μm is fabricated using a novel stamping method. The PCF is then brought into contact with the SU-8 pattern and an infra-red (IR) laser beam is passed through the fiber in order to soften the SU-8 surface; thereby selectively sealing some of the air channels with molten SU-8. Liquid crystals (LCs) are then infiltrated into the un-sealed holes in the PCF via capillary effects in order to modify the transmission properties of the PCF. Two selectively-filled PCFs are fabricated, namely an inner-ring LC-PCF and a single-line LC-PCF, respectively. It is shown that the two LC-PCFs exhibit significantly different optical behaviors. The practical applicability of the proposed selective-filling approach is demonstrated by fabricating an electric field sensor. The experimental results show that the sensor has the ability to measure electric fields with an intensity of up to 40 kV/cm.

  3. High resolution diffraction imaging of mercuric iodide: Demonstration of the necessity for alternate crystal processing techniques for highly purified material

    International Nuclear Information System (INIS)

    Steiner, B.; Berg, L. van den; Laor, U.

    1995-01-01

    The overall crystalline lattice uniformity in recently available, highly purified mercuric iodide single crystals has been shown to be impacted by crystal handling techniques that were previously satisfactory. High resolution diffraction imaging of the surface regularity of crystals of various levels of purity and growth orientation shows: (1) that the newer materials have a generally lower level of precipitates, (2) that the incidence of these precipitates is now closely correlated with growth direction, and (3) that the deformation resistance and resulting sensitivity to crystal handling procedures are also closely correlated with these factors in this soft material. As a result, gentler cutting and polishing procedures have been developed and are shown to be effective in preserving overall lattice regularity in the new material. The polishing required to remove residual surface scratches affect the lattice orientation of the softer, precipitate-free regions, while not affecting those regions with detectable levels of precipitates. These results correlate closely with the electrical properties of devices made from these crystals. Mercuric iodide single crystals have proved to be particularly useful for x and γ ray detectors because their room temperature operation allow for simple, efficient, and compact instrumentation

  4. The cytospin technique improves the detection of calcium pyrophosphate crystals in synovial fluid samples with a low leukocyte count.

    Science.gov (United States)

    Robier, Christoph; Quehenberger, Franz; Neubauer, Manfred; Stettin, Mariana; Rainer, Franz

    2014-06-01

    In synovial fluids (SF) with low leukocyte or/and crystal counts, important features may be missed, if exclusively smears are examined by polarized microscopy. That may be overcome by cytocentrifuges, which use low-speed centrifugal force to concentrate cells onto a glass slide and thus enhance the number of cells per high power field (HPF). We compared the calcium pyrophosphate (CPP) crystal counts in cytospin preparations with those in common smears of SF. The number of CPP crystals was counted in 50 SF samples by polarized microscopy, and statistical comparisons of the mean values of the cytospin and smear preparations were performed using the Wilcoxon test. The reproducibility within the slides of the cytocentrifuge and smear samples was determined by Spearman's rank correlation. The crystal counts were significantly higher in the cytospin than in the smear preparations (median 96/10 HPF vs. 2.5/10 HPF, p < 0.0001). The correlation in the crystal count between the slides 1 and 2 was significantly higher within the cytocentrifuge than in the smear group (0.97 vs. 0.73, p = 0.0004). CPP-negative cytospin preparations in initially smear-positive slides were not observed. We confirmed that the cytospin technique significantly enhances the number of examinable crystals per HPF, compared to common smears.

  5. Bioengineered magnetic crystals

    International Nuclear Information System (INIS)

    Kasyutich, O; Sarua, A; Schwarzacher, W

    2008-01-01

    In this paper we report on the successful application of a protein crystallization technique to fabricate a three-dimensionally ordered array of magnetic nanoparticles, i.e. a novel type of metamaterial with unique magnetic properties. We utilize ferritin protein cages for the template-constrained growth of superparamagnetic nanoparticles of magnetite/maghemite Fe 3 O 4 -γ-Fe 2 O 3 (magnetoferritin), followed by thorough nanoparticle bioprocessing and purification, and finally by protein crystallization. Protein crystallization is driven by the natural response of proteins to the supersaturation of the electrolyte, which leads to spontaneous nucleation and 3D crystal growth. Within a short period of time (hours to days) we were able to grow functional crystals on the meso-scale, with sizes of the order of tens, up to a few hundred micrometres. We present initial magnetic and Raman spectroscopy characterization results for the obtained 3D arrays of magnetic nanoparticles

  6. Kapitza conductance of metal single crystals by the second sound technique

    International Nuclear Information System (INIS)

    Wagner, F.; Kollarits, F.J.; Wilkes, K.E.; Yaqub, M.

    1975-01-01

    The Kapitza conductance h/sub K/ of high-purity single crystals of gallium, copper, lead, and tin, between 1.2 and 2 0 K, has been determined by an improved version of the second, sound method developed by Challis and Sherlock. By using a special mounting technique, strains in the samples were avoided on cooling. A comparison of the results with those given in the literature shows that our values of h/sub K/ are consistently higher than those obtained by using the steady-state method. By introducing different amounts of strain in a given sample its h/sub K/ was reduced by corresponding amounts. Thus, for a given metal, the entire range of reported steady-state values was covered. In the region of 1--2 0 K, strain not only reduces h/sub K/, but also increases the temperature dependence considerably. Although a reduction of h/sub K / with strain has been reported with the steady-state measurements, it is not accompanied by an increase in the temperature dependence. Possible reasons for this are discussed. Study of the superconductors lead and tin shows that the temperature exponent is nearly the same in the superconducting and normal states. The absolute value of h/sub K/ decreases in lead typically by 6 percent and increases in tin by 5 percent. (auth)

  7. Transient effects during erosion of WN by deuterium ions studied with the quartz crystal microbalance technique

    Energy Technology Data Exchange (ETDEWEB)

    Berger, Bernhard M., E-mail: berger@iap.tuwien.ac.at [Institute of Applied Physics, TU Wien, Fusion@ÖAW, Wiedner Hauptstr. 8-10, 1040 Vienna (Austria); Stadlmayr, Reinhard [Institute of Applied Physics, TU Wien, Fusion@ÖAW, Wiedner Hauptstr. 8-10, 1040 Vienna (Austria); Meisl, Gerd [Max-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching (Germany); Čekada, Miha [Jožef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Eisenmenger-Sittner, Christoph [Institute of Solid State Physics, TU Wien, Wiedner Hauptstr. 8-10, 1040 Vienna (Austria); Schwarz-Selinger, Thomas [Max-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching (Germany); Aumayr, Friedrich, E-mail: aumayr@iap.tuwien.ac.at [Institute of Applied Physics, TU Wien, Fusion@ÖAW, Wiedner Hauptstr. 8-10, 1040 Vienna (Austria)

    2016-09-01

    Transient effects during erosion of polycrystalline tungsten-nitride (WN) films by mono-energetic deuterium projectiles are studied using a quartz crystal microbalance technique. The evolution of the mass removal rate of a 360 nm thin WN film under 500 eV/D and 1000 eV/D bombardment is investigated at a temperature of 465 K in situ and in real-time as a function of the deuterium fluence. The measurements are performed at a typical flux of 10{sup 18} m{sup −2} s{sup −1}. A strong dependency of the observed mass change rate on the deuterium fluence is found. The mass loss is initially higher than for pure tungsten (W) and drops with fluence, finally reaching the same steady state value as for pure W sputtering. Steady state surface conditions are obtained at a fluence of about 0.2 × 10{sup 23} D/m{sup 2} for 500 eV/D and 0.6 × 10{sup 23} D/m{sup 2} for 1000 eV/D. SDTrimSP simulations indicate a preferential removal of N and a corresponding W enrichment of the surface.

  8. Combined ellipsometry and refractometry technique for characterisation of liquid crystal based nanocomposites.

    Science.gov (United States)

    Warenghem, Marc; Henninot, Jean François; Blach, Jean François; Buchnev, Oleksandr; Kaczmarek, Malgosia; Stchakovsky, Michel

    2012-03-01

    Spectroscopic ellipsometry is a technique especially well suited to measure the effective optical properties of a composite material. However, as the sample is optically thick and anisotropic, this technique loses its accuracy for two reasons: anisotropy means that two parameters have to be determined (ordinary and extraordinary indices) and optically thick means a large order of interference. In that case, several dielectric functions can emerge out of the fitting procedure with a similar mean square error and no criterion to discriminate the right solution. In this paper, we develop a methodology to overcome that drawback. It combines ellipsometry with refractometry. The same sample is used in a total internal reflection (TIR) setup and in a spectroscopic ellipsometer. The number of parameters to be determined by the fitting procedure is reduced in analysing two spectra, the correct final solution is found by using the TIR results both as initial values for the parameters and as check for the final dielectric function. A prefitting routine is developed to enter the right initial values in the fitting procedure and so to approach the right solution. As an example, this methodology is used to analyse the optical properties of BaTiO(3) nanoparticles embedded in a nematic liquid crystal. Such a methodology can also be used to analyse experimentally the validity of the mixing laws, since ellipsometry gives the effective dielectric function and thus, can be compared to the dielectric function of the components of the mixture, as it is shown on the example of BaTiO(3)/nematic composite.

  9. [Treatment of juvenile scoliosis: Increasing the lengthening interval with the growing rod technique should not necessarily compromise thoracic growth].

    Science.gov (United States)

    Pizones, J; Rodríguez-López, T; Zúñiga, L; Sánchez-Mariscal, F; Álvarez-González, P; Izquierdo, E

    2014-01-01

    Serial lengthening with growing rods is recommended every six months for the treatment of early onset scoliosis. The objective of this study was to evaluate the longitudinal growth of the thorax and control of the deformity in a series of patients with juvenile scoliosis when time intervals were increased between lengthenings. Retrospective study of eight patients. The following variables were measured: the Cobb angle, the apical vertebral translation, the coronal balance, thoracic T1-L1 length, thoracic T5-T12 kyphosis, the proximal junctional kyphosis (PJK) angle, and the lumbar lordosis. Complications were recorded. Five idiopathic and three syndromic scoliosis cases (mean age 9.4 ± 1.5 years) were evaluated. The initial surgery was followed by with an average of two distractions per patient. The mean time between distractions was 15.7 months. The final coronal main curve correction was 58%. Apical translation and coronal balance were improved and maintained after the surgeries. The thoracic (T1-L1) preoperative length was 20.8 cm, the postoperative length was 24.4 cm, and the final length was 26 cm. At the end of follow-up, the average growth of the thorax was 5.2 cm. The preoperative (T5-T12) kyphosis was 33.5°, and final 32.1°. The change in the PJK angle was 2.5° at the end of follow-up. Most complications were related to instrumentation. Two superficial wound infections were encountered. For less severe juvenile scoliosis patients treated with growing rods, spacing out lengthenings over more than a year can decrease the number of surgeries, while still controlling the deformity and allowing longitudinal thoracic growth. Copyright © 2014 SECOT. Published by Elsevier Espana. All rights reserved.

  10. Crystallization of isoelectrically homogeneous cholera toxin

    Energy Technology Data Exchange (ETDEWEB)

    Spangler, B.D.; Westbrook, E.M. (Argonne National Laboratory, IL (USA))

    1989-02-07

    Past difficulty in growing good crystals of cholera toxin has prevented the study of the crystal structure of this important protein. The authors have determined that failure of cholera toxin to crystallize well has been due to its heterogeneity. They have now succeeded in overcoming the problem by isolating a single isoelectric variant of this oligomeric protein (one A subunit and five B subunits). Cholera toxin purified by their procedure readily forms large single crystals. The crystal form has been described previously. They have recorded data from native crystals of cholera toxin to 3.0-{angstrom} resolution with our electronic area detectors. With these data, they have found the orientation of a 5-fold symmetry axis within these crystals, perpendicular to the screw dyad of the crystal. They are now determining the crystal structure of cholera toxin by a combination of multiple heavy-atom isomorphous replacement and density modification techniques, making use of rotational 5-fold averaging of the B subunits.

  11. Crystallization of isoelectrically homogeneous cholera toxin

    International Nuclear Information System (INIS)

    Spangler, B.D.; Westbrook, E.M.

    1989-01-01

    Past difficulty in growing good crystals of cholera toxin has prevented the study of the crystal structure of this important protein. The authors have determined that failure of cholera toxin to crystallize well has been due to its heterogeneity. They have now succeeded in overcoming the problem by isolating a single isoelectric variant of this oligomeric protein (one A subunit and five B subunits). Cholera toxin purified by their procedure readily forms large single crystals. The crystal form has been described previously. They have recorded data from native crystals of cholera toxin to 3.0-angstrom resolution with our electronic area detectors. With these data, they have found the orientation of a 5-fold symmetry axis within these crystals, perpendicular to the screw dyad of the crystal. They are now determining the crystal structure of cholera toxin by a combination of multiple heavy-atom isomorphous replacement and density modification techniques, making use of rotational 5-fold averaging of the B subunits

  12. 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.

  13. Diode-pumped laser with Yb:YAG single-crystal fiber grown by the micro-pulling down technique

    Science.gov (United States)

    Sangla, D.; Aubry, N.; Didierjean, J.; Perrodin, D.; Balembois, F.; Lebbou, K.; Brenier, A.; Georges, P.; Tillement, O.; Fourmigué, J.-M.

    2009-02-01

    Laser emission obtained from an Yb:YAG single-crystal fiber directly grown by the micro-pulling down technique is demonstrated for the first time. We achieved 11.2 W of continuous wave (CW) output power at 1031 nm for 55 W of incident pump power at 940 nm. In the Q-switched regime, we obtained pulses as short as 17 ns, for an average power of 2.3 W at 2 kHz corresponding to an energy of 1.15 mJ. In both cases, the M 2 factor was 2.5. This single-crystal fiber showed performance similar to a standard rod elaborated by the Czochralski method. The potential of Yb3+-doped single-crystal fibers is presented for scalable high-average and high-peak-power laser systems.

  14. Analysis of strictly bound modes in photonic crystal fibers by use of a source-model technique.

    Science.gov (United States)

    Hochman, Amit; Leviatan, Yehuda

    2004-06-01

    We describe a source-model technique for the analysis of the strictly bound modes propagating in photonic crystal fibers that have a finite photonic bandgap crystal cladding and are surrounded by an air jacket. In this model the field is simulated by a superposition of fields of fictitious electric and magnetic current filaments, suitably placed near the media interfaces of the fiber. A simple point-matching procedure is subsequently used to enforce the continuity conditions across the interfaces, leading to a homogeneous matrix equation. Nontrivial solutions to this equation yield the mode field patterns and propagation constants. As an example, we analyze a hollow-core photonic crystal fiber. Symmetry characteristics of the modes are discussed and exploited to reduce the computational burden.

  15. Comparison of surgical Limberg flap technique and crystallized phenol application in the treatment of pilonidal sinus disease: a retrospective study

    Science.gov (United States)

    Akan, Kaan; Tihan, Deniz; Duman, Uğur; Özgün, Yiğit; Erol, Fatih; Polat, Murat

    2013-01-01

    Objective: This study was designed to compare the efficacy of crystallized phenol method with Limberg flap in pilonidal sinus treatment. Material and Methods: Patients with a diagnosis of pilonidal sinus disease treated with surgical excision + Limberg rhomboid flap technique and crystallized phenol method between 2010–2011 in the Şevket Yılmaz Training and Research Hospital, Department of General Surgery were evaluated retrospectively. Patients’ age, sex, length of hospital stay, complications and recurrence rates were evaluated. Results: Eighty eight percent of patients were male and mean age was 26.84±6.41 in the Limberg group, and 24.72±5.00 in the crystallized phenol group. Sinus orifice locations and nature, and duration of symptoms before surgery were similar in the two groups. Length of hospital stay in the Limberg group was 1.46±0.61 days; whereas all patients in the crystallized phenol group were discharged on the same day. Infection, hematoma, wound dehiscence, and cosmetic problems were significantly higher in the Limberg group. There was no difference between the two groups in terms of recurrence and seroma formation. Conclusion: The less invasive method of crystallized phenol application may be an alternative approach to rhomboid excision and Limberg flap in patients with non-complicated pilonidal sinus disease, yielding acceptable recurrence rates. PMID:25931870

  16. Study on growth techniques and macro defects of large-size Nd:YAG laser crystal

    Science.gov (United States)

    Quan, Jiliang; Yang, Xin; Yang, Mingming; Ma, Decai; Huang, Jinqiang; Zhu, Yunzhong; Wang, Biao

    2018-02-01

    Large-size neodymium-doped yttrium aluminum garnet (Nd:YAG) single crystals were grown by the Czochralski method. The extinction ratio and wavefront distortion of the crystal were tested to determine the optical homogeneity. Moreover, under different growth conditions, the macro defects of inclusion, striations, and cracking in the as-grown Nd:YAG crystals were analyzed. Specifically, the inclusion defects were characterized using scanning electron microscopy and energy dispersive spectroscopy. The stresses of growth striations and cracking were studied via a parallel plane polariscope. These results demonstrate that improper growth parameters and temperature fields can enhance defects significantly. Thus, by adjusting the growth parameters and optimizing the thermal environment, high-optical-quality Nd:YAG crystals with a diameter of 80 mm and a total length of 400 mm have been obtained successfully.

  17. A technique for high-throughput protein crystallization in ionically cross-linked polysaccharide gel beads for X-ray diffraction experiments.

    Directory of Open Access Journals (Sweden)

    Michihiro Sugahara

    Full Text Available A simple technique for high-throughput protein crystallization in ionically cross-linked polysaccharide gel beads has been developed for contactless handling of crystals in X-ray crystallography. The method is designed to reduce mechanical damage to crystals caused by physical contact between crystal and mount tool and by osmotic shock during various manipulations including cryoprotection, heavy-atom derivatization, ligand soaking, and diffraction experiments. For this study, protein crystallization in alginate and κ-carrageenan gel beads was performed using six test proteins, demonstrating that proteins could be successfully crystallized in gel beads. Two complete diffraction data sets from lysozyme and ID70067 protein crystals in gel beads were collected at 100 K without removing the crystals; the results showed that the crystals had low mosaicities. In addition, crystallization of glucose isomerase was carried out in alginate gel beads in the presence of synthetic zeolite molecular sieves (MS, a hetero-epitaxic nucleant; the results demonstrated that MS can reduce excess nucleation of this protein in beads. To demonstrate heavy-atom derivatization, lysozyme crystals were successfully derivatized with K2PtBr6 within alginate gel beads. These results suggest that gel beads prevent serious damage to protein crystals during such experiments.

  18. Growth, mechanical, and magnetic study of SmFeO{sub 3} single crystal grown by optical floating zone technique

    Energy Technology Data Exchange (ETDEWEB)

    Babu, P. Ramesh [Centre for Crystal Growth, VIT University, Vellore, Tamil Nadu (India); Bhaumik, Indranil [Crystal Growth Laboratory, Laser Materials Development and Devices Division, RRCAT, Indore (India); Ganesamoorthy, S. [Material Science Group, IGCAR, Kalpakkam, Tamil Nadu (India); Kalainathan, S., E-mail: kalainathan@yahoo.com [Centre for Crystal Growth, VIT University, Vellore, Tamil Nadu (India); Bhatt, R.; Karnal, A.K.; Gupta, P.K. [Crystal Growth Laboratory, Laser Materials Development and Devices Division, RRCAT, Indore (India)

    2016-08-15

    Single crystals of Samarium orthoferrite (SmFeO{sub 3}) have been grown by the optical floating zone technique. The growth parameters to yield good quality crystals are 5 mm/h for pulling and 30–40 rpm for rotation. The mechanical behavior of the grown crystal has been investigated. Rosette pattern has been observed around the indentation and the microhardness has been found to decreases non-linearly with the applied load. For load higher than 1.96 N there is a transition from palmqvist to median crack due to plastic deformation of the crystal. The hardness parameters like fracture toughness, brittleness index, and yield strength have also been calculated for palmqvist and median cracks occurring on the crystal surface. The magnetic investigations revealed that a magnetic transition in the range of 300–180 K. Above 180 K, the magnetization decreases as Sm and Fe sublattices have opposite spins. At high temperature, two anomalies are observed, one due to near spin reorientation (T{sub SR} = 480 K) and the other is AFM to paramagnetic transitions (T{sub N} = 670 K). The M–H curves exhibit a shape change with temperature due to the emergence and enlargement of multi-domain state of the SmFeO{sub 3} crystals. Bloch parameter (3.28 × 10{sup −5} K{sup −3/2}) has also been evaluated. - Highlights: • SmFeO{sub 3} single crystals have been grown by OFZ technique in air. • The microhardness has been found to decreases non-linearly with the applied load. • At 472 K, spin reorientation occurs in Fe sublattice. • The M–H curves exhibit a shape change with temperature due to the emergence and enlargement of multi-domain state. • Bloch 3/2-law holds good for SmFeO{sub 3} (B-parameter as 3.28 × 10{sup −5} K{sup −3/2}).

  19. Synthesis, structural, optical and thermal properties of N-methyl-N-aryl benzamide organic single crystals grown by a slow evaporation technique

    Science.gov (United States)

    Prabukanthan, P.; Lakshmi, R.; Harichandran, G.; Kumar, C. Sudarsana

    2018-03-01

    The organic materials, N-methyl-N-aryl benzamides were synthesized from benzoylation of N-methyl-4-nitrobenzenamine (MNBA) using suitably substituted benzoyl chlorides. The products were purified by recrystallization and their single crystal were grown by a slow evaporation technique. The crystals were characterized by FTIR, UV-Vis-NIR, 1H &13C NMR, and single & powder X-ray diffraction. Thermal stability of the crystals was studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Dielectric and NLO properties of MNPB, FMNPB and MMNPB crystals were studied. The second harmonic generation (SHG) has been confirmed by the Kurtz powder test for all these crystals and the SHG efficiency of MMNPB crystal was found to be 2.25 times higher than that of KDP crystal.

  20. Development of a dual-ended readout detector with segmented crystal bars made using a subsurface laser engraving technique

    Science.gov (United States)

    Mohammadi, Akram; Yoshida, Eiji; Nishikido, Fumihiko; Nitta, Munetaka; Shimizu, Keiji; Sakai, Toshiaki; Yamaya, Taiga

    2018-01-01

    Depth of interaction (DOI) information is indispensable to improving the sensitivity and spatial resolution of positron emission tomography (PET) systems, especially for small field-of-view PET such as small animal PET and human brain PET. We have already developed a series of X’tal cube detectors for isotropic spatial resolution and we obtained the best isotropic resolution of 0.77 mm for detectors with six-sided readout. However, it is still challenging to apply the detector for PET systems due to the high cost of six-sided readout electronics and carrying out segmentation of a monolithic cubic scintillator in three dimensions using the subsurface laser engraving (SSLE) technique. In this work, we propose a more practical X’tal cube with a two-sided readout detector, which is made of crystal bars segmented in the height direction only by using the SSLE technique. We developed two types of prototype detectors with a 3 mm cubic segment and a 1.5 mm cubic segment by using 3  ×  3  ×  20 mm3 and 1.5  ×  1.5  ×  20 mm3 crystal bars segmented into 7 and 13 DOI segments, respectively, using the SSLE technique. First, the performance of the detector, composed of one crystal bar with different DOI segments and two thorough silicon via (TSV) multi-pixel photon counters (MPPCs) as readout at both ends of the crystal bar, were evaluated in order to demonstrate the capability of the segmented crystal bars as a DOI detector. Then, performance evaluation was carried out for a 4  ×  4 crystal array of 3  ×  3  ×  20 mm3 with 7 DOI segments and an 8  ×  8 crystal array of 1.5  ×  1.5  ×  20 mm3 with 13 DOI segments. Each readout included a 4  ×  4 channel of the 3  ×  3 mm2 active area of the TSV MPPCs. The three-dimensional position maps of the detectors were obtained by the Anger-type calculation. All the segments in the 4  ×  4 array were

  1. Development of non-destructive Young's modulus measurement techniques in non-oriented CeF$_{3}$ crystals

    CERN Document Server

    Pietroni, P; Lebeau, M; Majni, G; Rinaldi, D

    2005-01-01

    For a reliable mechanical assembly of scintillating crystals for the application to radiographic systems such as Positron Emission Tomographer (PET) and high-energy physics calorimeters (e.g. in CMS at CERN LHC), the evaluation of the monocrystal elastic constant (Young's modulus) is needed. Its knowledge is also essential in the photoelastic analysis for the determination of residual stresses. In this work non-destructive techniques based on elastic wave propagation are tested. They differ in the mechanical excitation device: instrumented hammer, traditional ultrasonic probes and laser- generated ultrasound. We have analysed three non-oriented cerium fluoride crystal samples produced for scintillation applications. Finally, we have validated the experimental results comparing them with the elastic constant calculated by using the stiffness matrix.

  2. A novel way to grow hemozoin-like crystals in vitro and its use to screen for hemozoin inhibiting antimalarial compounds.

    Directory of Open Access Journals (Sweden)

    Vincent Thomas

    Full Text Available BACKGROUND: Hemozoin crystals are normally formed in vivo by Plasmodium parasites to detoxify free heme released after hemoglobin digestion during its intraerythrocytic stage. Inhibition of hemozoin formation by various drugs results in free heme concentration toxic for the parasites. As a consequence, in vitro assays have been developed to screen and select candidate antimalarial drugs based on their capacity to inhibit hemozoin formation. In this report we describe new ways to form hemozoin-like crystals that were incidentally discovered during research in the field of prion inactivation. METHODS: We investigated the use of a new assay based on naturally occurring "self-replicating" particles and previously described as presenting resistance to decontamination comparable to prions. The nature of these particles was determined using electron microscopy, Maldi-Tof analysis and X-ray diffraction. They were compared to synthetic hemozoin and to hemozoin obtained from Plasmodium falciparum. We then used the assay to evaluate the capacity of various antimalarial and anti-prion compounds to inhibit "self-replication" (crystallisation of these particles. RESULTS: We identified these particles as being similar to ferriprotoporphyrin IX crystal and confirmed the ability of these particles to serve as nuclei for growth of new hemozoin-like crystals (HLC. HLC are morphologically similar to natural and synthetic hemozoin. Growth of HLC in a simple assay format confirmed inhibition by quinolines antimalarials at potencies described in the literature. Interestingly, artemisinins and tetracyclines also seemed to inhibit HLC growth. CONCLUSIONS: The described HLC assay is simple and easy to perform and may have the potential to be used as an additional tool to screen antimalarial drugs for their hemozoin inhibiting activity. As already described by others, drugs that inhibit hemozoin crystal formation have also the potential to inhibit misfolded proteins

  3. 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.

  4. Faceting, composition and crystal phase evolution in III-V antimonide nanowire heterostructures revealed by combining microscopy techniques

    Science.gov (United States)

    Xu, Tao; Dick, Kimberly A.; Plissard, Sébastien; Hai Nguyen, Thanh; Makoudi, Younes; Berthe, Maxime; Nys, Jean-Philippe; Wallart, Xavier; Grandidier, Bruno; Caroff, Philippe

    2012-03-01

    III-V antimonide nanowires are among the most interesting semiconductors for transport physics, nanoelectronics and long-wavelength optoelectronic devices due to their optimal material properties. In order to investigate their complex crystal structure evolution, faceting and composition, we report a combined scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning tunneling microscopy (STM) study of gold-nucleated ternary InAs/InAs1-xSbx nanowire heterostructures grown by molecular beam epitaxy. SEM showed the general morphology and faceting, TEM revealed the internal crystal structure and ternary compositions, while STM was successfully applied to characterize the oxide-free nanowire sidewalls, in terms of nanofaceting morphology, atomic structure and surface composition. The complementary use of these techniques allows for correlation of the morphological and structural properties of the nanowires with the amount of Sb incorporated during growth. The addition of even a minute amount of Sb to InAs changes the crystal structure from perfect wurtzite to perfect zinc blende, via intermediate stacking fault and pseudo-periodic twinning regimes. Moreover, the addition of Sb during the axial growth of InAs/InAs1-xSbx heterostructure nanowires causes a significant conformal lateral overgrowth on both segments, leading to the spontaneous formation of a core-shell structure, with an Sb-rich shell.

  5. Trace phase formation, crystallization kinetics and crystallographic evolution of a lithium disilicate glass probed by synchrotron XRD technique

    Science.gov (United States)

    Huang, Saifang; Huang, Zhaohui; Gao, Wei; Cao, Peng

    2015-03-01

    X-ray diffraction technique using a laboratory radiation has generally shown limitation in detectability. In this work, we investigated the in situ high-temperature crystallization of a lithium disilicate glass-ceramic in the SiO2-Li2O-CaO-P2O5-ZrO2 system with the aid of synchrotron radiation. The formation of lithium metasilicate and other intermediate phases in trace amount was successfully observed by synchrotron X-ray diffraction (SXRD). The crystallization mechanism in this glass was thus intrinsically revised to be the co-nucleation of lithium metasilicate and disilicate, instead of the nucleation of lithium disilicate only. The phase content, crystallite size and crystallographic evolutions of Li2Si2O5 in the glass-ceramic as a function of annealing temperature were studied by performing Rietveld refinements. It is found that the growth of Li2Si2O5 is constrained by Li2SiO3 phase at 580-700°C. The relationship between the crystallographic evolution and phase transition was discussed, suggesting a common phenomenon of structural response of Li2Si2O5 along its c axis to other silicon-related phases during glass crystallization.

  6. In Situ Mechanical Behavior of Mineral Crystals in Human Cortical Bone under Compressive Load Using Synchrotron X-Ray Scattering Techniques

    Science.gov (United States)

    Giri, Bijay; Almer, Jon D.; Dong, X. Neil; Wang, Xiaodu

    2012-01-01

    Mineral crystals, the major strength-bearing component of bone, are aligned in longitudinal bone with (00l) axes preferentially along the longitudinal axis, which in concert with crystal anisotropy leads to macroscopic anisotropy in mechanical behavior. Thus, it is of great interest to delineate the contributions of different subsets of mineral crystals as a function of orientation, on the bulk mechanical behavior of bone. Using a unique synergistic approach combining a progressive loading scheme and synchrotron X-ray scattering techniques, human cortical bone specimens were loaded in compression to examine the in situ mechanical behavior of mineral crystals as the function of orientation. The orientation distribution of mineral crystals was quantitatively estimated by measuring the X-ray diffraction intensity from the crystallographic (002) plane in different orientations. In addition, the average longitudinal (c-axis), transverse (a-axis), and shear strains of the subset of mineral crystals aligned in each orientation were determined by measuring the lattice deformation in the crystals normal to three distinct crystallographic planes (i.e. 002, 310, and 213). The experimental results indicated that the in situ strain and stress of mineral crystals varied with orientation. The normal strain and stress exerted on the longitudinally aligned mineral crystals were markedly greater than those on the transversely oriented crystals, whereas the shear stress reached a maximum for the crystals aligned in ±30° with respect to the loading direction, which coincided with the long axis of bone. The maximum principal strain and stress were observed in the mineral crystals oriented along the loading axis, with a similar trend observed in the maximum shear strain and stress. By examining their in situ behavior, the contribution of mineral crystals to load bearing and the bulk behavior of bone are discussed. PMID:22982959

  7. Electrospun PEDOT:PSS/PVP Nanofibers for CO Gas Sensing with Quartz Crystal Microbalance Technique

    OpenAIRE

    Hong-Di Zhang; Xu Yan; Zhi-Hua Zhang; Gu-Feng Yu; Wen-Peng Han; Jun-Cheng Zhang; Yun-Ze Long

    2016-01-01

    Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/polyvinylpyrrolidone (PEDOT:PSS/PVP) composite nanofibers were successfully fabricated via electrospinning and used as a quartz crystal microbalance (QCM) sensor for detecting CO gas. The electrical property of individual PEDOT:PSS/PVP nanofibers was characterized and the room temperature resistivity was at the magnitude of 105 Ω·m. The QCM sensor based on PEDOT:PSS/PVP nanofibers was sensitive to low concentration (5–50 ppm) CO. In the ...

  8. Growth and Characteristics of Bulk Single Crystals Grown from Solution on Earth and in Microgravity

    Science.gov (United States)

    Aggarwal, M. D.; Batra, A. K.; Lal, R. B.; Penn, Benjamin G.; Frazier, Donald O.

    2011-01-01

    The growth of crystals has been of interest to physicists and engineers for a long time because of their unique properties. Single crystals are utilized in such diverse applications as pharmaceuticals, computers, infrared detectors, frequency measurements, piezoelectric devices, a variety of high technology devices and sensors. Solution crystal growth is one of the important techniques to grow a variety of crystals when the material decomposes at the melting point and a suitable solvent is available to make a saturated solution at a desired temperature. In this chapter an attempt is made to give some fundamentals of growing crystals from solution including improved designs of various crystallizers. Since the same solution crystal growth technique could not be used in microgravity, authors had proposed a new cooled sting technique to grow crystals in space. Authors? experiences of conducting two space shuttle experiments relating to solution crystal growth are also detailed in this work. The complexity of these solution growth experiments to grow crystals in space are discussed. These happen to be some of the early experiments performed in space, and various lessons learned are described. A brief discussion of protein crystal growth that also shares basic principles of solution growth technique is given along with some flight hardware information for its growth in microgravity.

  9. Influence of the ytterbium doping technique on the luminescent properties of ZnSe single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Radevici, Ivan, E-mail: ivarad@utu.fi [Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Faculty of Physics and Engineering, Moldova State University, 60 A. Mateevici str., MD-2009 Chisinau, Republic of Moldova (Moldova, Republic of); Sushkevich, Konstantin [Faculty of Physics and Engineering, Moldova State University, 60 A. Mateevici str., MD-2009 Chisinau, Republic of Moldova (Moldova, Republic of); Huhtinen, Hannu [Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Nedeoglo, Dmitrii [Faculty of Physics and Engineering, Moldova State University, 60 A. Mateevici str., MD-2009 Chisinau, Republic of Moldova (Moldova, Republic of); Paturi, Petriina [Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland)

    2015-02-15

    Luminescent properties of the ytterbium doped zinc selenide crystals with 0.00–8.00 at % concentrations of the Yb impurity within the temperature interval from 6 K to 300 K were studied. Ytterbium doping was performed within three technological processes: during the growth by chemical vapor transport method and by thermal diffusion from the Bi+Yb or Zn+Yb melt. The influence of ytterbium impurity concentration on spectral position and intensity of the various photoluminescent bands in ZnSe emission spectra in visible and infrared range is analyzed. A tendency of ytterbium ions to form associates with background defects was demonstrated. A strong dependence between ytterbium influence on the zinc selenide emission spectra and concentration of selenium vacancies was shown. - Highlights: • Co-doping of ZnSe crystals with Yb and Bi or I impurities was studied. • Influence of Yb concentration on ZnSe emission spectra in visible and infrared range was analyzed. • Tendency of Yb to form associates with background defects was discussed. • Impact of V{sub Se} on formation of Yb-based emission centers was demonstrated.

  10. Determination of intrinsic polarization for K{sub 2}ZnCl{sub 4} single crystal grown by Czochralski technique for ferroelectric applications

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sonu [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi-7 (India); Ray, Geeta [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi-7 (India); Physics Department, Miranda House, University of Delhi, Delhi-7 (India); Sinha, Nidhi [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi-7 (India); Department of Electronics, SGTB Khalsa College, University of Delhi, Delhi-7 (India); Kumar, Binay, E-mail: b3kumar69@yahoo.co.in [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi-7 (India)

    2017-04-01

    Large sized single crystal of K{sub 2}ZnCl{sub 4} (KZC) was grown by Czochralski (Cz) technique. Structural parameters of KZC were determined by Single crystal X-ray diffraction (SCXRD). From DSC analysis and temperature dependent dielectric measurement, KZC crystal was found to show Curie phase transition at 151 °C. TG/DTA confirmed the melting point that was found to be 443 °C. The value of piezoelectric charge coefficient (d{sub 33}) for KZC crystal was found to be 32 pC/N demonstrating their applicability in transducers and piezoelectric devices. Ferroelectric P-E loop for the grown crystal was traced at room temperature and the intrinsic polarization obtained by PUND measurement was found to be 0.1398 μC/cm{sup 2} indicating its applicability in switching devices. The energy band gap for KZC single crystal was found to be 6.13 eV. Vickers micro-hardness test revealed soft nature of KZC single crystals. - Highlights: • Large sized K{sub 2}ZnCl{sub 4} (KZC) single crystal was grown by Czochralski technique. • It possesses high Curie temperature as 151 °C. • d{sub 33} coefficient was found to be 32 pC/N. • Intrinsic polarization measured by PUND. • Its direct band gap energy was calculated to be 6.13 eV.

  11. Ice Multiplication by Crystal Growth?Ice growing from the vapor along with tiny amounts of salt solution sheds free ice crystals, at -5C and saturation with respect to liquid water, in quiescent conditions. This is a more appealing explanation for the Hallett-Mossop effect than rime splintering, if it occurs primarily at temperatures near -5C.

    Science.gov (United States)

    Knight, C. A.

    2015-12-01

    Ice growing from the vapor, at -5C and liquid water supersaturation, often sheds crystals when it grows along with a small amount of salt solution. The experiments are done with single crystals growing in a temperature-controlled chamber with 5 ml of water in the bottom to maintain and control supersaturation, and the new crystals are detected when they fall into and nucleate the water in the bottom. Crystal growth is initiated by inserting into the growth chamber a pipet tip that contained a few microliters of very dilute salt solution that had been supercooled to -5C and nucleated at the tip. Growth from the vapor ensues, with condensation directly onto ice and onto whatever salt solution is exposed. The results are not completely reproducible, no doubt because the starting details of the exposure of ice and solution is not controllable. However, the shedding of crystals often occurs with starting NaCl concentrations of the order of 0.01 wt. percent, and almost never occurs with "pure" water. The shedding events themselves have not been identified, and an attractive hypothesis for how the shedding of ice occurs has not been found at the time of writing this abstract. By the time of the AGU meeting it is hoped that enough experiments will have been performed in order to say whether this effect is found only near -5C. If it requires a temperature near -5C then it seems to be an attractive explanation of the Hallett-Mossop process. It also, of course, is hoped that an attractive hypothesis for the mechanism of the shedding will have been found.

  12. Large-volume protein crystal growth for neutron macromolecular crystallography.

    Science.gov (United States)

    Ng, Joseph D; Baird, James K; Coates, Leighton; Garcia-Ruiz, Juan M; Hodge, Teresa A; Huang, Sijay

    2015-04-01

    Neutron macromolecular crystallography (NMC) is the prevailing method for the accurate determination of the positions of H atoms in macromolecules. As neutron sources are becoming more available to general users, finding means to optimize the growth of protein crystals to sizes suitable for NMC is extremely important. Historically, much has been learned about growing crystals for X-ray diffraction. However, owing to new-generation synchrotron X-ray facilities and sensitive detectors, protein crystal sizes as small as in the nano-range have become adequate for structure determination, lessening the necessity to grow large crystals. Here, some of the approaches, techniques and considerations for the growth of crystals to significant dimensions that are now relevant to NMC are revisited. These include experimental strategies utilizing solubility diagrams, ripening effects, classical crystallization techniques, microgravity and theoretical considerations.

  13. Study of In distribution on GaInSb:Al crystals by ion beam techniques

    Energy Technology Data Exchange (ETDEWEB)

    Streicher, M., E-mail: smorgana@gmail.com [Pontifícia Universidade Católica do Rio Grande do Sul, Av. Ipiranga, 6681, Porto Alegre, RS (Brazil); Instituto de Plasmas e Fusão Nuclear (IPFN), Instituto Superior Técnico, Universidade de Lisboa, E.N. 10, 2695-066 Bobadela LRS (Portugal); Corregidor, V.; Catarino, N. [Instituto de Plasmas e Fusão Nuclear (IPFN), Instituto Superior Técnico, Universidade de Lisboa, E.N. 10, 2695-066 Bobadela LRS (Portugal); Alves, L.C. [Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, E.N. 10, 2695-066 Bobadela LRS (Portugal); Franco, N. [Instituto de Plasmas e Fusão Nuclear (IPFN), Instituto Superior Técnico, Universidade de Lisboa, E.N. 10, 2695-066 Bobadela LRS (Portugal); Fonseca, M. [Universidade Europeia, Laureate International Universities, 1500-210 Lisboa (Portugal); Laboratório de Instrumentação, Engenharia Biomédica e Física da Radiação (LIBPhys-UNL), Departamento de Física, FCT-UNL, 2829-516 Monte da Caparica (Portugal); and others

    2016-03-15

    III–V ternary alloys semiconductor materials, in particular Ga{sub 1−x}In{sub x}Sb, are ideal candidates for device substrates because of the possibility to define the lattice constant as a function of the third element, indium. Aluminum, an isoelectric dopant for Ga and In, increases the carrier mobility in GaSb crystals and has influence over the concentration of native defects by passivating and/or compensating them. To understand the influence of Al on the distribution of indium in ternary alloys of Ga{sub 0.8}In{sub 0.2}Sb, pure and doped ingots were obtained with approximately 10{sup 20} atoms/cm{sup 3} of Al using a vertical Bridgman system. Analysis by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD), particle induced X-ray emission (PIXE) and particle induced gamma ray emission (PIGE) were used to obtain information on the structure defects and chemical composition of the crystals. The doped ingots showed good structural homogeneity when compared with the undoped alloy, and they were free from cracks and micro cracks. All of the obtained ingots present precipitates, twins and grains with different concentrations of In. The small compositional variation observed in the doped ingots along the radial direction (measured by PIXE), may be related to the solid–liquid interface’s quasi-equilibrium behavior. Regarding to the growth direction, it was observed that the undoped ingots exhibit a higher segregation phenomenon of the third element than the doped ingots. The obtained results indicate that aluminum influences the indium distribution in the ingots, thus ternary ingots with more homogeneous composition can be obtained and consequently electrical properties improved.

  14. Oscillating-Crucible Technique for Silicon Growth

    Science.gov (United States)

    Daud, T.; Dumas, K. A.; Kim, K. M.; Schwuttke, G. H.; Smetana, P.

    1984-01-01

    Technique yields better mixing of impurities and superior qualiity crystals. Accellerated motion stirs melt which reduces temperature gradients and decreases boundary layer for diffusion of impurities near growing surface. Results better mixing of impurities into melt, decrease in tendency for dendritic growth or cellular growth and crystals with low dislocation density. Applied with success to solution growth and Czochralski growth, resulting in large crystals of superior quality.

  15. Crystal structure analysis of LaMnO3 with x-ray diffraction technique using the Rietveld method

    International Nuclear Information System (INIS)

    Engkir Sukirman; Wisnu Ari Adi; Yustinus Purwamargapratala

    2010-01-01

    Crystal structure analysis of LaMnO 3 using the Rietveld method has been carried out. The LaMnO 3 sample was synthesized with high energy mechanical milling from the raw materials of La 2 O 3 and MnO 2 with the appropriate mol ratio. Milling were performed for 10 hours, pelletized and hereinafter sintered at 1350 °C for 6 hours. The sample characterizations covered the crystal structure and electric-magnetic properties of the materials by X-ray diffraction technique using the Rietveld method and the four point probe, respectively. The Rietveld refinement results based on the X-rays diffraction data indicate that the sample of LaMnO 3 is single phase with the crystal system: orthorhombic, the space group: Pnma No. 62 and the lattice parameters: a = 55.4405(9) Å; b = 7.717(1) Å dan c = 5.537(1) Å. The material owns Magnetic Resonance (MR) respond of 7 %, the mean value of crystallite size, D = 17 nm and lattice strain, e = - 0.5 %. So, the material go through a compressive strain, and according to the Nanda's strain model, it becomes a type G antiferromagnetic insulator. Because the insulator properties of the material does not change although being hit by the external magnetic field, hence the MR respond is only caused by the order of electron spin. Therefore at room temperature, LaMnO 3.0 just exhibits a small MR respond. (author)

  16. Growth of multiferroic Gd1-xYxMnO3 single crystals by optical floating zone technique

    International Nuclear Information System (INIS)

    Sarguna, R.M.; Ganesamoorthy, S.; Sridharan, V.; Subramanian, N.

    2014-01-01

    Rare earth manganites RMnO 3 with distorted perovskite structure are excellent multiferroic materials. The discovery of magnetic spin driven ferroelectricity in orthorhombic manganites (TbMnO 3 ) has sparked a surge in research into understanding the fundamental mechanism of multiferroic behavior. These systems fall under the category of type-2 multiferroics, the change of spatially modulated magnetic moment from sinusoidal to cycloidal gives rise to electric polarization. The magnetic structure depends upon the Mn-O-Mn bond angle. GdMnO 3 shows multiferroic properties only in the presence of applied magnetic field. When a magnetic field is applied along the b-axis, GdMnO 3 enters a ferroelectric state with an electric polarisation along the c-axis. By altering the Mn-O-Mn angle it is expected that GdMnO 3 will show multiferroic property even in the absence of magnetic field like TbMnO 3 . To alter the Mn-O-Mn bond angle GdMnO 3 was substituted with Y having lower ionic radius at Gd site. The effect of Y doping at the rare-earth site in GdMnO 3 investigated on polycrystalline samples of Gd 1-x Y x MnO 3 demonstrated a magneto-electric coupling in x=0.1-0.4. Single crystals are expected to give much amplified signal in respect of ferroelectric and magnetic properties. In this work we have grown Y substituted Gd 1-x Y x MnO 3 (x = 0.2, 0.3 and 0.4) by optical floating zone technique under different gas atmosphere. Growth rate of 1-2 mm/h yielded crack free crystals. Quality of the crystals was checked using Laue diffraction. Effect of growth rate and atmosphere pressure will be presented in this talk. (author)

  17. Study and identification of paramagnetic centers by EPR technique in K3Cu(CN)4 crystals irradiated with X-rays

    International Nuclear Information System (INIS)

    Tancredo, A.

    1984-01-01

    Paramagnetic centers created in K 3 Cu(CN) 4 crystals by X-ray irradiation, using EPR technique are studied. The crystals are irradiated in following conditions: a) liquid nitrogen temperatures, b) room temperatures. Crystals field models of the paramagnetic centers which determine the following local symmetric in order to satisfy experimental results: a) Cu ++ in C sub(3v) symmetric and b) K 0 in distorted octahedral symmetry are proposed. The decay of these centers and the observation that Cu ++ ions are very much instable and disappear at T = 148K are studied. The K 0 atom remain up to T approximatelly 300K. (E.G.) [pt

  18. The transport phenomena during the growth of ZnTe crystal by the temperature gradient solution growth technique

    Science.gov (United States)

    Yin, Liying; Jie, Wanqi; Wang, Tao; Zhou, Boru; Yang, Fan

    2017-03-01

    A numerical model is developed to simulate the temperature field, the thermosolutal convection, the solute segregation and the growth interface morphology during the growth of ZnTe crystal from Te rich solution by the temperature gradient solution growth (TGSG) technique. Effects of the temperature gradient on the transport phenomena, the growth interface morphology and the growth rate are examined. The influences of the latent heat and the thermal conductivity of ZnTe crystal on the transport phenomena and the growth interface are also discussed. We find that the mass transfer of ZnTe in the solution is very slow because of the low diffusion coefficient and the lack of mixing in the lower part of the solution. During the growth, dilute solution with high density and low growth temperature accumulates in the central region of the growth interface, making the growth interface change into two distinct parts. The inner part is very concave, while the outer part is relatively flat. Growth conditions in front of the two parts of the growth interface are different. The crystalline quality of the inner part of the ingot is predicted to be worse than that of the outer part. High temperature gradient can significantly increase the growth rate, and avoid the diffusion controlled growth to some extent.

  19. Diffusion of impurities in ionic crystals as studied by nuclear magnetic resonance techniques

    International Nuclear Information System (INIS)

    Richtering, H.; Becker, K.D.; Hamann, H.

    1976-01-01

    The method to investigate the diffusion of atomic defects in cubic ionic crystals by measurements of nmr relaxation rates is described very briefly. Examples are given for longitudinal and transversal relaxation of 81 Br- and 35 Cl-nuclei in LiBr, TlBr, AgCl, AgBr and CuBr. Selfdiffusion coefficients obtained for Cu + and Ag + in LiBr at temperatures above 350 0 C are D(Cu + ) = 8 exp(-1.0 eV/kT); D(Ag + ) = 1 exp(-1.0 eV/kT) cm 2 s -1 . In TlBr at 400 0 C the foreign ions K + , Rb + and Cs + have the same mean jump frequency. This frequency is about 3 times larger than that of Tl + and 3 times smaller than that of Br - . Ag + diffuses at 300 0 C 10 times faster than even Br - . In AgCl doped with CuCl the frequency of formation of a defect pair is observed. The jump processes connected with formation and recombination of this pair do not contribute considerably to Cu tracer diffusion. In AgBr doped with CuBr and treated with bromine the relaxation measurements show that Cu 2+ -ions are formed. The jump frequency of Cu 2+ can be determined besides that of Cu + at temperatures about 200 0 C. (orig.) [de

  20. Removal of Crystal Violet Dye from Aqueous Solutions onto Date Palm Fiber by Adsorption Technique

    Directory of Open Access Journals (Sweden)

    Mashael Alshabanat

    2013-01-01

    Full Text Available The adsorption of crystal violet (CV onto date palm fibers (DPFs was examined in aqueous solution at 25°C. The experimental maximum adsorption capacity value was 0.66×10−6. Langmuir, Freundlich, Elovich and Temkin models were applied to describe the equilibrium isotherms. The influence of pH and temperature on dye removal was evaluated. The percentage removal of CV dye by adsorption onto DPF at different pH and temperatures showed that these factors play a role in the adsorption process. Thermodynamic analysis was performed, and the Gibbs free energy ΔGο, enthalpy change ΔHο, and entropy ΔSο were calculated. The negative values of ΔGο indicate spontaneous adsorption. The negative value of ΔHο indicates that the interaction between CV and DPF is exothermic, and the positive value of ΔSο indicates good affinity between DPF and CV. The kinetic data were fitted to a pseudo-second-order model.

  1. 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.

  2. Metal-assisted and microwave accelerated-evaporative crystallization: Application to lysozyme protein

    Science.gov (United States)

    Mauge-Lewis, Kevin

    In response to the growing need for new crystallization techniques that afford for rapid processing times along with control over crystal size and distribution, the Aslan Research Group has recently demonstrated the use of Metal-Assisted and Microwave-Accelerated Evaporative Crystallization MA-MAEC technique in conjunction with metal nanoparticles and nanostructures for the crystallization of amino acids and organic small molecules. In this study, we have employed the newly developed MA-MAEC technique to the accelerated crystallization of chicken egg-white lysozyme on circular crystallization platforms in order to demonstrate the proof-of-principle application of the method for protein crystallization. The circular crystallization platforms are constructed in-house from poly (methyl methacrylate) (PMMA) and silver nanoparticle films (SNFs), indium tin oxide (ITO) and iron nano-columns. In this study, we prove the MA-MAEC method to be a more effective technique in the rapid crystallization of macromolecules in comparison to other conventional methods. Furthermore, we demonstrate the use of the novel iCrystal system, which incorporates the use of continuous, low wattage heating to facilitate the rapid crystallization of the lysozyme while still retaining excellent crystal quality. With the incorporation of the iCrystal system, we observe crystallization times that are even shorter than those produced by the MA-MAEC technique using a conventional microwave oven in addition to significantly improved crystal quality.

  3. Simulation of stray grain formation in Ni-base single crystal turbine blades fabricated by HRS and LMC techniques

    Directory of Open Access Journals (Sweden)

    Ya-feng Li

    2017-03-01

    Full Text Available The simulation models of the thermal and macrostructural evolutions during directional solidification of Ni-base single crystal (SX turbine blades under high rate solidification (HRS and liquid metal cooling (LMC have been constructed using ProCAST software, coupled with a 3D Cellular Automaton Finite Element (CAFE model. The models were used to investigate the tendencies of stray grain (SG formation in the platform region of turbine blades fabricated by HRS and LMC techniques. The results reveal that the LMC technique can prohibit SG formation by smoothing the concaved isotherm and in turn alleviating the undercooling in the platform ends to let the dendrites fill up the undercooled zone before SG nucleation. The simulation results agreed well with the experimental results, indicating that these models could be used to analyze the macrostructural evolution or to optimize process parameters to suppress SG formation. Using these models, the critical withdrawal rate for casting SX turbine blades without SG formation were determined to be around 75 μm·s-1 and 100 μm·s-1 for HRS and LMC respectively, suggesting that LMC can be used as an efficient technique in fabricating SX turbine blades without any SG defect formation.

  4. The effectiveness of pendulum, K-loop, and distal jet distalization techniques in growing children and its effects on anchor unit: A comparative study.

    Science.gov (United States)

    Marure, Pravinkumar S; Patil, Raju Umaji; Reddy, Sumitra; Prakash, Amit; Kshetrimayum, Nillachandra; Shukla, Rajeevkumar

    2016-01-01

    A common strategy to correct Class II malocclusions using a nonextraction protocol in children is to move the maxillary molars distally using molar distalization appliances, which usually derive their anchorage from maxillary premolars, causing mesialization of premolars and protrusion of incisors. To evaluate the skeletal, dental and soft tissue changes produced by three different distalizing appliances, namely, pendulum, K-loop, and distal jet appliances. Sixty-six children of mean age 14.13 years requiring molar distalization were divided into three groups: Group I (pendulum appliance), Group II (K-loop), and Group III (distal jet). Lateral cephalometric films were taken before and after 5 months of molar distalization and following cephalometric parameters were used to assess the effects of maxillary molar distalization, namely, anteroposterior skeletal (SNA/SNB/ANB), vertical skeletal (face height ratio/Frankfort-mandibular plane [FMA]/angle formed between Maxillary plane & Mandibular plane (MM)), interdental (overjet/overbite), maxillary dentoalveolar, and soft tissue parameters. There was no significant age difference between the three groups. In overall treatment changes among the three groups, the Anteroposterior skeletal changes were not statistically significant, vertically FMA angle increased by 1.79° ± 2.25° and overbite reduced by 2.38 ± 1.83 mm. The maxillary first molars were distalized by an average of 4.70 ± 3.01 mm (Upper 6 [U6] to pterygoid vertical [PTV]). The maxillary central incisor labial tipping increased to an average of 1.61 ± 2.73 mm and cant of upper lip increased by 3.40° ± 5.88° are statistically significant (P < 0.05). All three distalization techniques in growing children produced significant effects on anchor unit. There was an increase in FMA angle, significant bite opening, proclination of the maxillary incisors and increase in the cant of the upper lip.

  5. Crucible Grows Wide Silicon Ribbon

    Science.gov (United States)

    Seidensticker, R.

    1982-01-01

    Inexpensive manufacture of solar cells may require quality silicon ribbon crystals. One way to produce them is by growing wide dendritic webs, which can be very long and have high structural perfection. Dendrites grow from supercooled melt, so width of ribbon depends on how wide a region of supercooled molten silicon can be maintained in crucible. Elongated geometry of suscepter/crucible/lid assembly allows molten silicon to supercool over a wider region -- a necessary condition for the growth of wide dendritic crystal ribbon.

  6. ACRT technique for the single crystal growth of the heavy fermion compound YbRh{sub 2}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Witt, Sebastian; Kliemt, Kristin; Butzke, Constantin; Krellner, Cornelius [Goethe University Frankfurt, 60438 Frankfurt am Main (Germany)

    2016-07-01

    In the heavy fermion compound YbRh{sub 2}Si{sub 2} the antiferromagnetic ordering below 70 mK close to a quantum critical point is well-studied. Beneath the magnetic ordering a new phase transition was found recently at 2 mK. It is necessary to prepare large and high-quality single crystals for studying the nature of this new phase transition. Besides the optimization of the single crystal growth it is important to investigate single crystals with different isotopes at this phase transition. Here, we report the crystal growth of YbRh{sub 2}Si{sub 2} with the accelerated crucible rotation technique (ACRT). ACRT shows for other compounds, e.g. YAG (yttrium aluminum garnet, Y{sub 3}Al{sub 5}O{sub 12}), that this technique can reduce flux impurities and enhance the yield of larger crystals. We also report the attempt to receive metallic isotopes of ytterbium with metallothermic reduction. Crystals with different isotopes of silicon and ytterbium can be used for NMR measurements to investigate the underlying phenomena of quantum criticality in more detail.

  7. The growth of benzophenone crystals by Sankaranarayanan–Ramasamy (SR) method and slow evaporation solution technique (SEST): A comparative investigation

    International Nuclear Information System (INIS)

    Senthil Pandian, M.; Boopathi, K.; Ramasamy, P.; Bhagavannarayana, G.

    2012-01-01

    Highlights: ► Benzophenone single crystal was grown by Sankaranarayanan–Ramasamy method which has the sizes of 1060 mm length and 55 mm diameter for the first time. ► The conventional and SR-grown benzophenone crystals were characterized and compared using HRXRD, etching, laser damage threshold, microhardness, UV-transmittance, birefringence and dielectric analysis. ► The SR-grown benzophenone crystal has higher LDT, microhardness, transparency, dielectric permittivity, birefringence and lower FWHM, EPD, dielectric loss than the crystal grown by conventional method. ► The probable reason for higher crystalline perfection in SR-grown crystal was discussed. -- Abstract: Longest unidirectional〈1 0 0〉 benzophenone (BP) crystal having dimension of 1060 mm length and 55 mm diameter was grown by Sankaranarayanan–Ramasamy method. The growth rate was measured by monitoring the elevation of the crystal–solution interface at different temperatures. The high resolution X-ray diffraction and etching measurements indicate that the unidirectional grown benzophenone crystal has good crystalline perfection and less density of defects. The optical damage threshold of SEST and SR grown BP crystals has been investigated and found that the SR grown benzophenone crystal has higher laser damage threshold value than the conventional method grown crystal. Microhardness measurement shows that crystals grown by SR method have a higher mechanical stability than the crystals grown by SEST method. Dielectric permittivity and birefringence are high in SR grown crystal compared to SEST grown BP crystal. The UV–vis-NIR results show that SR method grown crystal exhibits 7% higher transmittance as against crystals grown by conventional method.

  8. 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.

  9. Growth rate anisotropy and absorption studies on β-BaB 2O 4 single crystals grown by the top-seeded solution growth technique

    Science.gov (United States)

    Bhatt, Rajeev; Ganesamoorthy, S.; Bhaumik, Indranil; Karnal, A. K.; Wadhawan, V. K.

    2007-03-01

    Beta barium borate (β-BaB2O4; BBO) single crystals have been grown from Na2O flux by the TSSG technique and the observed growth rate anisotropy is reported. The symmetrical conoscopic interference pattern on the c-cut plate confirmed strain-free and optical homogeneity of the crystals. The observed growth habits of as-grown crystals are explained using crystal growth theories. The relative growth rate along different crystallographic directions of BBO can be described by R[100] = R[010] > R[001]. The absorption measurements show a nearly 9 nm shift in fundamental absorption edges in X and Z cut samples. Band gap energies measured were 6.45 and 6.2 eV along the X and Z directions, respectively. The absorption spectra near the fundamental absorption edges (AE) follow Urbach's rule.

  10. Crystal growth of YVO[sub 4] using the LHPG technique

    Energy Technology Data Exchange (ETDEWEB)

    Erdei, S. (Materials Research Lab., Pennsylvania State Univ., University Park (United States)); Ainger, F.W. (Materials Research Lab., Pennsylvania State Univ., University Park (United States))

    1993-03-01

    A laser heated pedestal growth (LHPG) technique utilizing a 50 W CO[sub 2] laser source was employed for the growth of YVO[sub 4]. A growth method where only a small volume of the substance is melted was selected, since vanadium oxides vaporize readily at the melting point of YVO[sub 4] (1810 C). The feed and seed rods were prepared from ceramics made from different Y[sub 2]O[sub 3]-V[sub 2]O[sub 5] compositions synthesized by both solid state and wet chemical methods. The congruent melting composition (CMC) was determined to be 49.3 mol% V[sub 2]O[sub 5]-50.7 mol% Y[sub 2]O[sub 3]. Two phases in addition to YVO[sub 4] were observed and found to be Y[sub 8]V[sub 2]O[sub 17] and a black crystalline YVO[sub 4-x] (0 < x < 1) which can be deduced from the Y[sub 2]O[sub 3]-V[sub 2]O[sub 5]-V[sub 2]O[sub 3] ternary phase diagram. The occurrence of these phases can be minimized by reducing the length of the float zone and using ceramic rods rich in V[sub 2]O[sub 5]. (orig.)

  11. Unidirectional seeded single crystal growth from solution of benzophenone

    Science.gov (United States)

    Sankaranarayanan, K.; Ramasamy, P.

    2005-07-01

    A novel crystal growth method has been established for the growth of single crystal with selective orientation at room temperature. Using volatile solvent, the saturated solution containing the material to be crystallized was taken in an ampoule and allowed to crystallize by slow solvent evaporation assisted with a ring heater. The orientation of the growing crystal was imposed by means of a seed fixed at the bottom of the ampoule. By selecting a suitable ring heater voltage and by controlling the ring heater voltage, nucleation and the growth rate of the crystal were controlled more effectively. By employing this novel method, benzophenone single crystal ingots of diameters 10 and 20 mm and length more than 50 mm were successfully grown using xylene as solvent. The ease in scaling up of diameter from 10 to 20 mm shows the vital advantage of this technique. It was possible to achieve solute-crystal conversion efficiency of 100 percent. The grown benzophenone crystal was characterized by FTIR, TG and DTA, powder X-ray diffraction, X-ray rocking curve, optical transmission study and powder SHG measurement. The results show that the crystal quality is at least as good as the quality of the crystal grown by other known methods. Also, microbial growth was naturally avoided in this method, as the fresh solution is constantly made available for the growing crystal.

  12. Growing Pains

    CERN Multimedia

    Katarina Anthony

    2013-01-01

    Heat expands and cold contracts: it’s a simple thermodynamic rule. But when temperatures swing from 300 K to near-absolute zero, this rule can mean a contraction of more than 80 metres across the LHC’s 27-km-long cryogenic system. Keeping this growth in check are compensators (a.k.a. bellows), which shrink and stretch in response to thermodynamic changes. Leak tests and X-rays now underway in the tunnel have revealed that these “joints” might be suffering from growing pains…   This 25-μm weld crack is thought to be the cause of the helium leaks. Prior to the LS1 warm-up, CERN’s cryogenic experts knew of two points in the machine’s cryogenic distribution system that were leaking helium. Fortunately, these leaks were sufficiently small, confined to known sub-sectors of the cryogenic line and – with help from the vacuum team (TE-VSC) – could easily be compensated for. But as the machine warmed up f...

  13. Crystal and electronic structure study of AgAu and AgCu bimetallic alloy thin films by X-ray techniques

    Energy Technology Data Exchange (ETDEWEB)

    Ozkendir, O. Murat, E-mail: ozkendir@gmail.com [Mersin University, Faculty of Technology, Energy Systems Engineering, Tarsus (Turkey); Mersin University, Institute of Natural Science, Department of Nanotechnology and Advanced Materials, Mersin (Turkey); Cengiz, E. [Karadeniz Technical University, Faculty of Science, Department of Physics, Trabzon (Turkey); Yalaz, E. [Mersin University, Institute of Natural Science, Department of Nanotechnology and Advanced Materials, Mersin (Turkey); Söğüt, Ö.; Ayas, D.H. [Kahramanmaraş Sütçü İmam Üniversitesi, Faculty of Science and Letters, Department of Physics, Kahramanmaraş (Turkey); Thammajak, B. Nirawat [Synchrotron Light Research Institute (Public Organisation), 111 University Avenue, T. Suranaree, A. Muang, Nakhon Ratchasima 30000 (Thailand)

    2016-05-15

    Highlights: • Crystal and electronic properties of bimetallic AgCu and AgAu alloy thin films were studied. • Both AgCu and AgAu bimetallic samples were determined to have cubic crystal geometry. • Strong influence of Cu and Au atoms on the electronic structure of the Ag atoms were determined. - Abstract: Crystal and electronic structure properties of bimetallic AgAu and AgCu alloy thin films were investigated by X-ray spectroscopic techniques. The aim of this study is to probe the influence of Au or Cu atoms on the electronic behaviors of Ag ions in bimetallic alloy materials that yields different crystal properties. To identify the mechanisms causing crystal phase transitions, study were supported by the collected EXAFS (Extended X-ray Absorption Fine Structure) data. Crystal structures of both Cu and Au doped bimetallic Ag samples were determined mainly in cubic geometry with “Fm3m” space group. Through the Ag–Au and Ag–Cu molecular interactions during bimetallic alloy formations, highly overlapped electronic levels that supports large molecular band formations were observed with different ionization states. Besides, traces of the d–d interactions in Au rich samples were determined as the main interplay in the broad molecular bond formations. The exact atomic locations and types in the samples were determined by EXAFS studies and supported by the performed calculations with FEFF scientific code.

  14. Compact Liquid Crystal Based Tunable Band-Stop Filter with an Ultra-Wide Stopband by Using Wave Interference Technique

    Directory of Open Access Journals (Sweden)

    Longzhu Cai

    2017-01-01

    Full Text Available A wave interference filtering section that consists of three stubs of different lengths, each with an individual stopband of its own central frequency, is reported here for the design of band-stop filters (BSFs with ultra-wide and sharp stopbands as well as large attenuation characteristics. The superposition of the individual stopbands provides the coverage over an ultra-wide frequency range. Equations and guidelines are presented for the application of a new wave interference technique to adjust the rejection level and width of its stopband. Based on that, an electrically tunable ultra-wide stopband BSF using a liquid crystal (LC material for ultra-wideband (UWB applications is designed. Careful treatment of the bent stubs, including impedance matching of the main microstrip line and bent stubs together with that of the SMA connectors and impedance adaptors, was carried out for the compactness and minimum insertion and reflection losses. The experimental results of the fabricated device agree very well with that of the simulation. The centre rejection frequency as measured can be tuned between 4.434 and 4.814 GHz when a biased voltage of 0–20 Vrms is used. The 3 dB and 25 dB stopband bandwidths were 4.86 GHz and 2.51 GHz, respectively, which are larger than that of other recently reported LC based tunable BSFs.

  15. Thermomechanical and Photophysical Properties of Crystal-Violet-Dye/H2O Based Dissolutions via the Pulsed Laser Photoacoustic Technique

    Directory of Open Access Journals (Sweden)

    Vicente Torres-Zúñiga

    2014-01-01

    Full Text Available Different thermoelastic parameters, for example, the acoustic attenuation and the speed of sound, are fundamental for instrumental calibration and quantitative characterization of organic-based dissolutions. In this work, these parameters as functions of the concentration of an organic dye (crystal-violet: CV in distillated water (H2O based dissolutions are investigated. The speed of sound was measured by the pulsed-laser photoacoustic technique (PLPA, which consists in the generation of acoustic-waves by the optical absorption of pulsed light in a given material (in this case a liquid sample. The thermally generated sound-waves traveling through a fluid are detected with two piezoelectric sensors separated by a known distance. An appropriate processing of the photoacoustic signals allows an adequate data analysis of the generated waves within the system, providing an accurate determination of the speed of sound as function of the dye-concentration. The acoustic attenuation was calculated based on the distance of the two PZT-microphones to an acoustic-source point and performing linear-fitting of the experimental data (RMS-amplitudes as function of the dye-concentration. An important advantage of the PLPA-method is that it can be implemented with poor or null optical transmitting materials permitting the characterization of the mechanical and concentration/aggregate properties of dissolved organic compounds.

  16. Microscopy and Chemical Inversing Techniques to Determine the Photonic Crystal Structure of Iridescent Beetle Scales in the Cerambycidae Family

    Science.gov (United States)

    Richey, Lauren; Gardner, John; Standing, Michael; Jorgensen, Matthew; Bartl, Michael

    2010-10-01

    Photonic crystals (PCs) are periodic structures that manipulate electromagnetic waves by defining allowed and forbidden frequency bands known as photonic band gaps. Despite production of PC structures operating at infrared wavelengths, visible counterparts are difficult to fabricate because periodicities must satisfy the diffraction criteria. As part of an ongoing search for naturally occurring PCs [1], a three-dimensional array of nanoscopic spheres in the iridescent scales of the Cerambycidae insects A. elegans and G. celestis has been found. Such arrays are similar to opal gemstones and self-assembled colloidal spheres which can be chemically inverted to create a lattice-like PC. Through a chemical replication process [2], scanning electron microscopy analysis, sequential focused ion beam slicing and three-dimensional modeling, we analyzed the structural arrangement of the nanoscopic spheres. The study of naturally occurring structures and their inversing techniques into PCs allows for diversity in optical PC fabrication. [1] J.W. Galusha et al., Phys. Rev. E 77 (2008) 050904. [2] J.W. Galusha et al., J. Mater. Chem. 20 (2010) 1277.

  17. A simple technique to reduce evaporation of crystallization droplets by using plate lids with apertures for adding liquids

    Science.gov (United States)

    Zipper, Lauren E.; Aristide, Xavier; Bishop, Dylan P.; Joshi, Ishita; Kharzeev, Julia; Patel, Krishna B.; Santiago, Brianna M.; Joshi, Karan; Dorsinvil, Kahille; Sweet, Robert M.; Soares, Alexei S.

    2014-01-01

    A method is described for using plate lids to reduce evaporation in low-volume vapor-diffusion crystallization experiments. The plate lids contain apertures through which the protein and precipitants were added to different crystallization microplates (the reservoir was filled before fitting the lids). Plate lids were designed for each of these commonly used crystallization microplates. This system minimizes the dehydration of crystallization droplets containing just a few nanolitres of protein and precipitant, and results in more reproducible diffraction from the crystals. For each lid design, changes in the weight of the plates were used to deduce the rate of evaporation under different conditions of temperature, air movement, droplet size and precipitant. For comparison, the state of dehydration was also visually assessed throughout the experiment. Finally, X-ray diffraction methods were used to compare the diffraction of protein crystals that were conventionally prepared against those that were prepared on plates with plate lids. The measurements revealed that the plate lids reduced the rate of evaporation by 63–82%. Crystals grown in 5 nl drops that were set up with plate lids diffracted to higher resolution than similar crystals from drops that were set up without plate lids. The results demonstrate that plate lids can be instrumental for improving few-nanolitre crystallizations. PMID:25484231

  18. Single crystal time-of-flight neutron diffraction of Cr3Si and MnF2: Comparison with monochromatic beam techniques

    International Nuclear Information System (INIS)

    Jauch, W.; Schultz, A.J.

    1987-01-01

    Single-crystal time-of-flight (TOF) neutron diffraction data have been collected for Cr 3 Si and MnF 2 with the Argonne Intense Pulsed Neutron Source. The purpose of this study was to test the accuracy of the TOF technique by a comparison with results from recent γ-ray, X-ray and neutron diffraction experiments. The results show that for simple crystal structures the positional and thermal parameters obtained from TOF data approach those obtained by other diffraction methods. (orig.)

  19. 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.

  20. 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.

  1. A quality comparison of protein crystals grown under containerless conditions generated by diamagnetic levitation, silicone oil and agarose gel.

    Science.gov (United States)

    Cao, Hui-Ling; Sun, Li-Hua; Li, Jian; Tang, Lin; Lu, Hui-Meng; Guo, Yun-Zhu; He, Jin; Liu, Yong-Ming; Xie, Xu-Zhuo; Shen, He-Fang; Zhang, Chen-Yan; Guo, Wei-Hong; Huang, Lin-Jun; Shang, Peng; He, Jian-Hua; Yin, Da-Chuan

    2013-10-01

    High-quality crystals are key to obtaining accurate three-dimensional structures of proteins using X-ray diffraction techniques. However, obtaining such protein crystals is often a challenge. Several containerless crystallization techniques have been reported to have the ability to improve crystal quality, but it is unknown which is the most favourable way to grow high-quality protein crystals. In this paper, a quality comparison of protein crystals which were grown under three containerless conditions provided by diamagnetic levitation, silicone oil and agarose gel was conducted. A control experiment on a vessel wall was also simultaneously carried out. Seven different proteins were crystallized under the four conditions, and the crystal quality was assessed in terms of the resolution limit, the mosaicity and the Rmerge. It was found that the crystals grown under the three containerless conditions demonstrated better morphology than those of the control. X-ray diffraction data indicated that the quality of the crystals grown under the three containerless conditions was better than that of the control. Of the three containerless crystallization techniques, the diamagnetic levitation technique exhibited the best performance in enhancing crystal quality. This paper is to our knowledge the first report of improvement of crystal quality using a diamagnetic levitation technique. Crystals obtained from agarose gel demonstrated the second best improvement in crystal quality. The study indicated that the diamagnetic levitation technique is indeed a favourable method for growing high-quality protein crystals, and its utilization is thus potentially useful in practical efforts to obtain well diffracting protein crystals.

  2. Development of the mercury iodide semiconductor crystal for application as a radiation detector

    International Nuclear Information System (INIS)

    Martins, Joao Francisco Trencher

    2011-01-01

    In this work, the establishment of a technique for HgI growth and preparation of crystals, for use as room temperature radiation semiconductor detectors is described. Three methods of crystal growth were studied while developing this work: physical vapor transport (PVT); saturated solution of HgI 2 , using two different solvents; (a) dimethyl sulfoxide (DMSO) and (b) acetone, and the Bridgman method. In order to evaluate the obtained crystals by the three methods, systematic measurements were carried out for determining the stoichiometry, structure, orientation, surface morphology and impurity of the crystal. The influence of these physical chemical properties on the crystals development was studied, evaluating their performance as radiation detectors. The X-ray diffractograms indicated that the crystals were, preferentially, oriented in the (001) e (101) directions with tetragonal structure for all crystals. Nevertheless, morphology with a smaller deformation level was observed for the crystal obtained by the PVT technique, comparing to other methods. Uniformity on the surface layer of the PVT crystal was detected, while clear incrustations of elements distinct from the crystal could be viewed on the DMSO crystal surface. The best results as to radiation response were found for the crystal grown by physical vapor transport. Significant improvement in the HgI z2 radiation detector performance was achieved for purer crystals, growing the crystal twice by PVT technique. (author)

  3. Protein crystal growth - Growth kinetics for tetragonal lysozyme crystals

    Science.gov (United States)

    Pusey, M. L.; Snyder, R. S.; Naumann, R.

    1986-01-01

    Results are reported from theoretical and experimental studies of the growth rate of lysozyme as a function of diffusion in earth-gravity conditions. The investigations were carried out to form a comparison database for future studies of protein crystal growth in the microgravity environment of space. A diffusion-convection model is presented for predicting crystal growth rates in the presence of solutal concentration gradients. Techniques used to grow and monitor the growth of hen egg white lysozyme are detailed. The model calculations and experiment data are employed to discuss the effects of transport and interfacial kinetics in the growth of the crystals, which gradually diminished the free energy in the growth solution. Density gradient-driven convection, caused by presence of the gravity field, was a limiting factor in the growth rate.

  4. Effects of long-term exposure to elevated CO(2) conditions in slow-growing plants using a (12)C-enriched CO(2)-labelling technique.

    Science.gov (United States)

    Pardo, Antoni; Aranjuelo, Iker; Biel, Carmen; Savé, Robert; Azcón-Bieto, Joaquim; Nogués, Salvador

    2009-01-01

    Despite their relevancy, long-term studies analyzing elevated CO(2) effect in plant production and carbon (C) management on slow-growing plants are scarce. A special chamber was designed to perform whole-plant above-ground gas-exchange measurements in two slow-growing plants (Chamaerops humilis and Cycas revoluta) exposed to ambient (ca. 400 micromol mol(-1)) and elevated (ca. 800 micromol mol(-1)) CO(2) conditions over a long-term period (20 months). The ambient isotopic (13)C/(12)C composition (delta(13)C) of plants exposed to elevated CO(2) conditions was modified (from ca. -12.8 per thousand to ca. -19.2 per thousand) in order to study carbon allocation in leaf, shoot and root tissues. Elevated CO(2) increased plant growth by ca. 45% and 60% in Chamaerops and Cycas, respectively. The whole-plant above-ground gas-exchange determinations revealed that, in the case of Chamaerops, elevated CO(2) decreased the photosynthetic activity (determined on leaf area basis) as a consequence of the limited ability to increase C sink strength. On the other hand, the larger C sink strength (reflected by their larger CO(2) stimulatory effect on dry mass) in Cycas plants exposed to elevated CO(2) enabled the enhancement of their photosynthetic capacity. The delta(13)C values determined in the different plant tissues (leaf, shoot and root) suggest that Cycas plants grown under elevated CO(2) had a larger ability to export the excess leaf C, probably to the main root. The results obtained highlighted the different C management strategies of both plants and offered relevant information about the potential response of two slow-growing plants under global climate change conditions. Copyright (c) 2008 John Wiley & Sons, Ltd.

  5. Evaluation of bent-crystal x-ray backlighting and microscopy techniques for the Sandia Z machine.

    Science.gov (United States)

    Sinars, Daniel B; Bennett, Guy R; Wenger, David F; Cuneo, Michael E; Porter, John L

    2003-07-01

    X-ray backlighting and microscopy systems for the 1-10-keV range based on spherically or toroidally bent crystals are discussed. These systems are ideal for use on the Sandia Z machine, a megajoule-class x-ray facility. Near-normal-incidence crystal microscopy systems have been shown to be more efficient than pinhole cameras with the same spatial resolution and magnification [Appl. Opt. 37, 1784 (1998)]. We show that high-resolution (< or = 10 microm) x-ray backlighting systems using bent crystals can be more efficient than analogous point-projection imaging systems. Examples of bent-crystal-backlighting results that demonstrate 10-microm resolution over a 20-mm field of view are presented.

  6. New Programs Utilizing Light Scattering and Flow Imaging Techniques for Macromolecular Crystal Growth and Fluid Dynamics Studies

    Science.gov (United States)

    2003-01-01

    Dr. Phil Segre, a physicist by training, is a recent addition to the Biotech group, SD46, having joined NASA in August of 2000. Over the past two years he has been developing a laboratory for the study of macromolecular and protein crystal growth. The main apparatus for this work is a Dynamic Light Scattering apparatus, DLS, which is capable of making highly precise measurements of size distributions of both protein solutions and protein crystals. With Drs. Chernov and Thomas (USRA), he has begun a collaboration studying the affects of protein impurities on protein crystal growth and subsequent crystal quality. One of the hypotheses behind the differences between Earth and space grown protein crystals is that the absorption of harmful impurities is reduced in space due to the absence of convective flows. Using DLS measurements we are examining crystal growth with varying amounts of impurities and testing whether there is a strong physical basis behind this hypothesis. With Dr. Joe Ng of UAH he has been collaborating on a project to examine the folding/unfolding dynamics of large RNA complexes. A detailed understanding of this process is necessary for the handling of RNA in biotech applications, and the DLS instrument gives details and results beyond that of other instruments. With Prof. Jim McClymer of the University of Maine (summer faculty visitor to NASA in 2001, 2002), we have been studying the crystallization process in model colloidal suspensions whose behavior in some cases can mimic that of much smaller protein solutions. An understanding of the self-assembly of colloids is the first step in the process of engineering novel materials for photonic and light switching applications. Finally, he has begun an investigation into the physics of particle sedimentation. In addition to the DLS instrument he also has an instrument (called PIV) that can measure flow fields of fluids. The applications are to the dynamics of protein crystal motions both on earth and in

  7. Transretroperitoneal CT-guided Embolization of Growing Internal Iliac Artery Aneurysm after Repair of Abdominal Aortic Aneurysm: A Transretroperitoneal Approach with Intramuscular Lidocaine Injection Technique

    Energy Technology Data Exchange (ETDEWEB)

    Park, Joon Young, E-mail: pjy1331@hanmail.net; Kim, Shin Jung, E-mail: witdd2@hanmail.net; Kim, Hyoung Ook, E-mail: chaos821209@hanmail.net [Chonnam National University Hospital, Department of Radiology (Korea, Republic of); Kim, Yong Tae, E-mail: mono-111@hanmail.net [Chonnam National University Hwasun Hospital, Department of Radiology (Korea, Republic of); Lim, Nam Yeol, E-mail: apleseed@hanmail.net; Kim, Jae Kyu, E-mail: kjkrad@jnu.ac.kr [Chonnam National University Hospital, Department of Radiology (Korea, Republic of); Chung, Sang Young, E-mail: sycpvts@jnu.ac.kr; Choi, Soo Jin Na, E-mail: choisjn@jnu.ac.kr; Lee, Ho Kyun, E-mail: mhaha@hanmail.net [Chonnam National University Hospital, Department of Surgery (Korea, Republic of)

    2015-02-15

    This study was designed to evaluate the efficacy and safety of CT-guided embolization of internal iliac artery aneurysm (IIAA) after repair of abdominal aortic aneurysm by transretroperitoneal approach using the lidocaine injection technique to iliacus muscle, making window for safe needle path for three patients for whom CT-guided embolization of IIAA was performed by transretroperitoneal approach with intramuscular lidocaine injection technique. Transretroperitoneal access to the IIAA was successful in all three patients. In all three patients, the IIAA was first embolized using microcoils. The aneurysmal sac was then embolized with glue and coils without complication. With a mean follow-up of 7 months, the volume of the IIAAs remained stable without residual endoleaks. Transretroperitoneal CT-guided embolization of IIAA using intramuscular lidocaine injection technique is effective, safe, and results in good outcome.

  8. Direct costs associated with the management of progressive early onset scoliosis: estimations based on gold standard technique or with magnetically controlled growing rods.

    Science.gov (United States)

    Charroin, C; Abelin-Genevois, K; Cunin, V; Berthiller, J; Constant, H; Kohler, R; Aulagner, G; Serrier, H; Armoiry, X

    2014-09-01

    The main disadvantage of the surgical management of early onset scoliosis (EOS) using conventional growing rods is the need for iterative surgical procedures during childhood. The emergence of an innovative device using distraction-based magnetically controlled growing rods (MCGR) provides the opportunity to avoid such surgeries and therefore to improve the patient's quality of life. Despite the high cost of MCGR and considering its potential impact in reducing hospital stays, the use of MCGR could reduce medical resource consumption in a long-term view in comparison to traditional growing rod (TGR). A cost-simulation model was constructed to assess the incremental cost between the two strategies. The cost for each strategy was estimated based on probability of medical resource consumption determined from literature search as well as data from EOS patients treated in our centre. Some medical expenses were also estimated from expert interviews. The time horizon chosen was 4 years as from first surgical implantation. Costs were calculated in the perspective of the French sickness fund (using rates from year 2013) and were discounted by an annual rate of 4%. Sensitivity analyses were conducted to test model strength to various parameters. With a time horizon of 4 years, the estimated direct costs of TGR and MCGR strategies were 49,067 € and 42,752 €, respectively leading to an incremental costs of 6135 € in favour of MCGR strategy. In the first case, costs were mainly represented by hospital stays expenses (83.9%) whereas in the other the cost of MCGR contributed to 59.5% of the total amount. In the univariate sensitivity analysis, the tariffs of hospital stays, the tariffs of the MCG, and the frequency of distraction surgeries were the parameters with the most important impact on incremental cost. MCGR is a recent and promising innovation in the management of severe EOS. Besides improving the quality of life, its use in the treatment of severe EOS is likely to

  9. 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.

  10. 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.

  11. Neutron beam applications - Development of single crystal structure analysis technique using the HANARO neutron four circle diffractometer

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Il Hwan; Kim, Moon Jib; Kim, Jin Gyu [Chungnam National University, Taejon (Korea)

    2000-04-01

    As the four circle diffractometer (FCD) has been set up in HANARO, it has become possible to study the single crystal structures by means of the neutron diffraction. Taking account of the geometry of the FCD, a program for the control of te FCD and neutron data acquisition operating under Windows' circumstance has been accomplished. Also, a computer program which can automatically measure the diffraction intensity data has been developed. All data obtained from the FCD are processed automatically for further work and a software for the single crystal structure analyses has been prepared. A KC1 single crystal was selected as first test sample for a structure analysis had been successfully performed on the FCD using in-house developed program and accordingly their functionings with precision were confirmed. For regular single crystal diffraction experiments, the structure analyses of chrysoberyl and Zr(Y)0{sub 1.87} single crystals were performed using both neutron and X-ray diffraction methods, and the result showed that the neutron diffraction work is superior to the X-ray one from the viewpoint of certain crystallographic information obtainable only from the former one. 24 refs., 15 figs., 15 tabs. (Author)

  12. Control and homogenization of oxygen distribution in Si crystals by the novel technique: electromagnetic Czochralski method (EMCZ)

    Science.gov (United States)

    Watanabe, Masahito; Eguchi, Minoru; Hibiya, Taketoshi

    1999-07-01

    A novel method for control and homogenization oxygen distribution in silicon crystals by using electromagnetic force (EMF) to rotate the melt without crucible rotation has been developed. We call it electromagnetic Czochralski method. An EMF in the azimuthal direction is generated in the melt by the interaction between an electric current through the melt in the radial direction and a vertical magnetic field. (B). The rotation rate (ωm) of the silicon melt is continuously changed from 0 to over 105 rpm under I equals 0 to 8 A and B equals 0 to 0.1 T. Thirty-mm-diameter silicon single crystals free of dislocations could be grown under several conditions. The oxygen concentration in the crystals was continuously changed from 1 X 1017 to 1 X 1018 atoms/cm3 with increase of melt rotation by electromagnetic force. The homogeneous oxygen distributions in the radial directions were achieved. The continuous change of oxygen concentration and the homogenization of oxygen distribution along the radial direction are attributed to the control of the diffusion-boundary-layer at both the melt/crucible and crystal/melt by forced flow due to the EMF. This new method would be useful for growth of the large-diameter silicon crystals with a homogeneous distribution of oxygen.

  13. Effects of La{sup 3+}–Nd{sup 3+} ions and pre-calcination on the growth of hexaferrite nanoparticles prepared by gel to crystallization technique: Non-isothermal crystallization kinetics analysis

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Ankush [Department of Physics, Jaipur Engineering College and Research Centre, Jaipur (India); Barman, P.B. [Department of Physics and Materials Science, Jaypee University of Information Technology, Waknaghat (India); Singh, R.R., E-mail: raginirajsingh@gmail.com [Department of Physics and Materials Science, Jaypee University of Information Technology, Waknaghat (India)

    2015-04-15

    This is the first report ever on La{sup 3+}–Nd{sup 3+} doped M-type hexaferrite nanoparticles: SrNd{sub x}La{sub y}Fe{sub 12−x−y}O{sub 19} (0 ≤ x ≤ 1) prepared by citrate precursor using the sol–gel technique followed by gel to crystallization. The substitution effects of ions and molar ratio of Fe{sup 3+}/Sr{sup 2+} on the formation of ferrite phase were examined using powder differential thermal analysis (DTA) technique, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (Mid-IR) and vibrating sample magnetometer (VSM). The present work aim to study the crystallization of binary La{sup 3+}- Nd{sup 3+} doped hexaferrite nanoparticles. DTA technique was employed to investigate the formation of nanocrystalline SrNd{sub 0.4}La{sub 0.4}Fe{sub 11.2}O{sub 19} and revealed that the formation of ferrite phase was occurred in steps and crystallization take place by the means of endothermic reactions. The value of activation energy and crystallization temperature has been obtained from DTA data using different non-isothermal methods. XRD and Mid-IR studies have confirmed the formation of ferrite phase. Through this work an optimum calcination condition was established for the synthesis of single phase hexaferrite nanoparticles even after the substitution of binary rare earth elements. Magnetic properties were determined by using a vibrating sample magnetometer. The magnetic results revealed that the synthesized nanoparticles are suitable for perpendicular recording media due to their high coercivity value. - Highlights: • First report of studies on Nd{sup 3+}–La{sup 3+} doped M-type strontium hexaferrite nanoparticles. • Studied the crystallization of binary (Nd{sup 3+}–La{sup 3+}) doped hexaferrite nanoparticles. • Studied the effects of La{sup 3+}–Nd{sup 3+} & molar ratio of Fe{sup 3+}/Sr{sup 2+} on the formation of ferrite phase. • Established an optimum condition to obtain single phase hexaferrite nanoparticles. • Magnetic

  14. A study of PbTiO sub 3 crystallization in pure and composite nanopowders prepared by the sol-gel technique

    CERN Document Server

    Cernansky, M; Kral, K; Krupkova, R

    2002-01-01

    In this investigation the crystallization of PbTiO sub 3 upon annealing of pure nanopowders and PbTiO sub 3 -SiO sub 2 (1:1 v/v) nanocomposite powders prepared by the sol-gel technique was studied. Using x-ray diffraction phase analysis, the start of PbTiO sub 3 crystallization in pure PbTiO sub 3 powders was detected at 400 sup o C. Distinct crystallization of PbTiO sub 3 in PbTiO sub 3 -SiO sub 2 nanocomposites starts at 700 sup o C, whereas SiO sub 2 remains amorphous. There are indications that an interface interaction between the PbTiO sub 3 and the SiO sub 2 phase plays an important role in hindering the crystallization of PbTiO sub 3. The particle size (size of coherently scattering regions) was estimated from the broadening of the x-ray diffraction line profiles. The average size of PbTiO sub 3 nanocrystallites increases with temperature and time of annealing, the influence of temperature being more significant than that of the annealing time. Differential scanning calorimetry confirmed the results of...

  15. Growth and Characterization of Detector-Grade Cd0.9Zn0.1Te Crystals by the Traveling Heater Method with the Accelerated Crucible Rotation Technique

    Science.gov (United States)

    Zhou, Boru; Jie, Wanqi; Wang, Tao; Xu, Yadong; Yang, Fan; Yin, Liying; Zhang, Binbin; Nan, Ruihua

    2018-02-01

    The accelerated crucible rotation technique has been applied in the traveling heater method process for the growth of CdZnTe:In (CZT:In) ingots. Full single crystalline wafers with a diameter of 53 mm were obtained under optimized growth conditions. The crystalline quality and the photoelectric properties of the CZT crystals were characterized using infrared transmission microscopy, infrared transmittance spectra, current-voltage (I-V) analysis and gamma ray radiation response measurements. The CZT crystals show no Te inclusions over 3 μm in size and those smaller than 3 μm have a density of 105 cm-3. The resistivity of the crystals reaches 3.92 × 1010 Ω/cm-1 by fitting the I-V curve. The mobility-lifetime ( μτ) product of the electrons is 4.12 × 10-3 cm2/V. Based on the CZT crystals, planar configuration and quasi-hemispherical configuration detectors were fabricated and show a resolution of 3.67% at 241Am@59.5 keV and 1.95% at 137Cs@662 keV, respectively, which indicates a superior detection performance.

  16. Development of technique for high-pressure single-crystal neutron scattering and its application to studies of magnetic materials

    International Nuclear Information System (INIS)

    Osakabe, Toyotake

    2012-01-01

    In this article, a new high-pressure apparatus for single-crystal magnetic neutron diffraction under 10 GPa is described. First, new hybrid-anvil, which is composed of an opposed pair of a supported SiC anvil and a tungsten carbide (WC) anvil with a center-dimpled culet, is introduced. Next, results of an investigation of pressure-transmitting media are shown. The hydrostaticity of the media is essential for the single-crystal diffraction experiments. Finally, a thermal neutron focusing device with a lot of curved supermirrors is shown. The device can compensate weak magnetic signals from tiny samples in high-pressure cells. As examples of the studies using the apparatus, the high-pressure single-crystal magnetic neutron diffraction experiments on 4f-electron systems PrFe 4 P 12 and HoB 2 C 2 are taken up. (author)

  17. The Langmuir-Blodgett Technique as a Tool for Homeotropic Alignment of Fluorinated Liquid Crystals Mixed with Arachidic Acid

    Directory of Open Access Journals (Sweden)

    Anna Modlińska

    2011-08-01

    Full Text Available Some fluoro-substituted liquid crystals mixed with arachidic acid in monolayers formed at air-liquid (Langmuir films and air-solid substrate (Langmuir-Blodgett films interfaces were investigated. Molecular organization in Langmuir films was determined on the basis of the analysis of the shape of the surface pressure-mean molecular area isotherm and observations made by means of a Brewster angle microscope. It was found that in the compression process the liquid crystal molecules are pushed out towards the top of the first monolayer being in direct contact with the subphase. Langmuir films were transferred onto the quartz substrates at various surface pressures and mono- and multilayered Langmuir-Blodgett films were obtained. The films were characterized using electronic absorption measurements. The conditions for obtaining the homeotropic orientation of the liquid crystal molecules were determined.

  18. ASM Inaugural Lecture 2010: Single crystal X-ray structural determination: A powerful technique for natural products research and drug discovery

    International Nuclear Information System (INIS)

    Fun Hoong Kun; Chantrapromma, S.; Boonnak, N.; Lee, V.S.

    2010-01-01

    Drug discovery from natural products resources have been extensively studied worldwide because natural products with their great structural diversity have traditionally provided most of the drugs in use. They offer major opportunities for finding novel low molecular weight leading-structures that are active against a wide range of assay targets. The most important step in the discovery process is the identification of compounds with interesting biological activity. Single crystal X-ray structure determination is a powerful technique for natural products research and drug discovery. The detailed three-dimensional structures that emerge can be co-related to the activities to these structures. In this article the following is presented: (i) co-crystal and disorder structures; (ii) determination of absolute configuration and (iii) the ability to distinguish between whether a natural product compound is a natural product or a natural product artifact. All these three properties are unique to the technique of single crystal X-ray structure determination. Case (iii) was demonstrated with a compound containing a chromene ring, namely macluraxanthone (which was isolated from Cratoxylum formosum subsp. pruniflorum, a Thai medicinal plant). (author)

  19. Benchmarking state-of-the-art numerical simulation techniques for analyzing large photonic crystal membrane line defect cavities

    DEFF Research Database (Denmark)

    Gregersen, Niels; de Lasson, Jakob Rosenkrantz; Frandsen, Lars Hagedorn

    2018-01-01

    In this work, we perform numerical studies of two photonic crystal membrane microcavities, a short line-defect L5 cavity with relatively low quality (Q) factor and a longer L9 cavity with high Q. We compute the cavity Q factor and the resonance wavelength λ of the fundamental M1 mode in the two...

  20. The growth of sapphire single crystals

    Directory of Open Access Journals (Sweden)

    STEVAN DJURIC

    2001-06-01

    Full Text Available Sapphire (Al2O3 single crystals were grown by the Czochralski technique both in air and argon atmospheres. The conditions for growing sapphire single crystals were calculated by using a combination of Reynolds and Grashof numbers. Acritical crystal diameter dc = 20 mm and the critical rate of rotation wc = 20 rpm were calculated from the hydrodynamics of the melt. The value of the rate of crystal growth was experimentally found to be 3.5 mm/h. According to our previous experiments, it was confirmed that three hours exposures to conc. H3PO4 at 593 K was suitable for chemical polishing. Also, three hours exposure to conc.H3PO4 at 523 K was found to be a suitable etching solution. The lattice parameters a = 0.47573 nm and c = 1.29893 nm were determined by X-ray powder diffraction. The obtained results are discussed and compared with published data.

  1. 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.

  2. Protein crystal growth in low gravity

    Science.gov (United States)

    Feigelson, Robert S.

    1993-01-01

    This Final Technical Report for NASA Grant NAG8-774 covers the period from April 27, 1989 through December 31, 1992. It covers five main topics: fluid flow studies, the influence of growth conditions on the morphology of isocitrate lyase crystals, control of nucleation, the growth of lysozyme by the temperature gradient method and graphoepitaxy of protein crystals. The section on fluid flow discusses the limits of detectability in the Schlieren imaging of fluid flows around protein crystals. The isocitrate lyase study compares crystals grown terrestrially under a variety of conditions with those grown in space. The controlling factor governing the morphology of the crystals is the supersaturation. The lack of flow in the interface between the drop and the atmosphere in microgravity causes protein precipitation in the boundary layer and a lowering of the supersaturation in the drop. This lowered supersaturation leads to improved crystal morphology. Preliminary experiments with lysozyme indicated that localized temperature gradients could be used to nucleate crystals in a controlled manner. An apparatus (thermonucleator) was designed to study the controlled nucleation of protein crystals. This apparatus has been used to nucleate crystals of materials with both normal (ice-water, Rochelle salt and lysozyme) and retrograde (horse serum albumin and alpha chymotrypsinogen A) solubility. These studies have lead to the design of an new apparatus that small and more compatible with use in microgravity. Lysozyme crystals were grown by transporting nutrient from a source (lysozyme powder) to the crystal in a temperature gradient. The influence of path length and cross section on the growth rate was demonstrated. This technique can be combined with the thermonucleator to control both nucleation and growth. Graphoepitaxy utilizes a patterned substrate to orient growing crystals. In this study, silicon substrates with 10 micron grooves were used to grow crystals of catalase

  3. Contribution to the study of water stress on olive growing under the effect of climate change behind the soil and water conservation techniques in South East of Tunisia

    Science.gov (United States)

    Hachani, Amal; Ouessar, Mohamed; Zerrim, Ammar

    2015-04-01

    Climate change (CC) is a main issue of interest at the international as well as the national levels. It is important at this stage to guide the research to the analysis of impacts and adaptation strategies. The objective of this study is to evaluate the water stress of the olive within the context of CC behind the soil and water conservation techniques in the South East of Tunisia (watershed of Oum Zessar, Medenine) using hydrological modeling (HidroMORE model). Data on rainfall and temperature were collected from available stations, while those for future scenarios (Horizons 2030 and 2090) were obtained using the Coupled Model Intercomparison Project Phase 5 CMIP5 (GFDL HIRAM C360). Model parameterization was based from already conducted studies in the region while estimations have been made for the other case. In comparison with the reference period (1996-2005) and following the increase in temperature (1°C) and (5°C) and rainfall decrease of (5.4%) and (20%), ET0 recorded an increase of (3%) (9%) and ETCadj was reduced by (13%) and (30%), respectively for the 2030 and 2090 horizons. Thus, it is expected that the land suitable for olive cultivation will experience shrinkage and this cropping system would become increasingly problematic.

  4. Application of extended-crystal diffraction techniques to the symmetry and structure analysis of 221-PbBiSrCaCuO

    International Nuclear Information System (INIS)

    Goodman, P.; Miller, P.

    1993-01-01

    The discovery of a series of layer-perovskite superconducting compounds by Maeda et al. (1988) presented a challenge for present day electron diffraction techniques, due to their common occurrence as mixed phases, and the existence of complex structural modulations of more than one type. Cowley's (1976) theory developed specifically for describing diffraction effects from layered crystals having a micro-domainal sub-structure seems particularly well suited to the task of solving these structures, while the technique of extended-crystal diffraction is shown here to be capable of providing data of sufficient precision for this analysis. The present study is made on the 221 compound of PbBiSrCaCuO. Using the above diffraction techniques it is shown that the true symmetry of the whole structure is orthorhombic, Amaa, and not monoclinic as previously assumed, and that the superlattice reflections arise as a result of a basic microdomainal constitution, rather than from a uniform and incommensurate modulation. 8 figs

  5. Nonlinear optical refraction of Al2O3 single crystal doping with nickel nanoparticles measured by the Kerr-lens autocorrelation technique

    International Nuclear Information System (INIS)

    Yu, Xiangxiang; Wang, Yuhua; Wang, Yumei

    2014-01-01

    The nonlinear refraction of a nickel doped α-Al 2 O 3 single crystal was measured with a 800 nm pulse using the Kerr-lens autocorrelation technique. The sample was fabricated by ion implantation using a metal vapor vacuum arc ion source. The value of the nonlinear refractive index, n 2 , of the sample was determined to be 7.9 × 10 −16 cm 2 W −1 . The mechanisms of nonlinear refraction of the bulk material and the nanoparticles have been discussed through the UV–vis spectrum and supercontinuum spectra. (paper)

  6. Large Silver Halide Single Crystals as Charged Particle Track Detectors

    Science.gov (United States)

    Kusmiss, J. H.

    1972-01-01

    The trajectory of the particle is made visible under a microscope by the accumulation of metallic silver at regions of the lattice damaged by the particle. This decoration of the particle track is accomplished by exposure of the crystal to light. The decoration of normally present lattice imperfections such as dislocations can be suppressed by the addition to the crystal of less than ten parts per million of a suitable polyvalent metal impurity. An account of some preliminary attempts to grow thin single crystals of AgCl is given also, and suggestions for a more refined technique are offered.

  7. Crystal Structure, Optical, and Electrical Properties of SnSe and SnS Semiconductor Thin Films Prepared by Vacuum Evaporation Techniques for Solar Cell Applications

    Science.gov (United States)

    Ariswan; Sutrisno, H.; Prasetyawati, R.

    2017-05-01

    Thin films of SnSe and SnS semiconductors had been prepared by vacuum evaporation techniques. All prepared samples were characterized on their structure, optical, and electrical properties in order to know their application in technology. The crystal structure of SnSe and SnS was determined by X-Ray Diffraction (XRD) instrument. The morphology and chemical composition were obtained by Scanning Electron Microscopy (SEM) coupled with Energy Dispersive of X-Ray Analysis (EDAX). The optical property such as band gap was determined by DR-UV-Vis (Diffuse Reflectance-Ultra Violet-Visible) spectroscopy, while the electrical properties were determined by measuring the conductivity by four probes method. The characterization results indicated that both SnSe and SnS thin films were polycrystalline. SnSe crystallized in an orthorhombic crystal system with the lattice parameters of a = 11.47 Å, b = 4.152 Å and c = 4.439 Å, while SnS had an orthorhombic crystal system with lattice parameters of a = 4.317 Å, b = 11.647 Å and c = 3.981 Å. Band gaps (Eg) of SnSe and SnS were 1.63 eV and 1.35 eV, respectively. Chemical compositions of both thin films were non-stoichiometric. Molar ratio of Sn : S was close to ideal which was 1 : 0.96, while molar ratio of Sn : S was 1 : 0.84. The surface morphology described the arrangement of the grains on the surface of the thin film with sizes ranging from 0.2 to 0.5 microns. Color similarity on the surface of the SEM images proved a homogenous thin layer.

  8. Domain wall motion and magnetization reversal processes in a FeSi picture frame single crystal studied by the time-dependent neutron depolarization technique

    International Nuclear Information System (INIS)

    Schaik, F.J. van.

    1979-01-01

    The three dimensional neutron depolarization technique, which gives detailed information about the static properties of ferromagnetic materials, has been extended to a method by means of which the time dependence of magnetic phenomena can be studied. The measurement of the neutron depolarization against time is made possible by applying a periodical magnetic field on the investigated specimen and by continuous sampling of the transmitted neutron intensity in time channels, which are started synchronously with the applied field. The technique has been used in the study of the magnetic domain structure at room temperature of a (010) [001] picture frame FeSi single crystal (3.5 wt.% Si) with outer dimensions of (15 x 10 x 0.26) mm and a frame width of 2.78 mm. (Auth.)

  9. Crystal growth, structural, thermal and mechanical behavior of L-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) single crystals

    Science.gov (United States)

    Mahadevan, M.; Ramachandran, K.; Anandan, P.; Arivanandhan, M.; Bhagavannarayana, G.; Hayakawa, Y.

    2014-12-01

    Single crystals of L-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) have been grown successfully from the solution of L-arginine and 4-nitrophenol. Slow evaporation of solvent technique was adopted to grow the bulk single crystals. Single crystal X-ray diffraction analysis confirms the grown crystal has monoclinic crystal system with space group of P21. Powder X-ray diffraction analysis shows the good crystalline nature. The crystalline perfection of the grown single crystals was analyzed by HRXRD by employing a multicrystal X-ray diffractometer. The functional groups were identified from proton NMR spectroscopic analysis. Linear and nonlinear optical properties were determined by UV-Vis spectrophotometer and Kurtz powder technique respectively. It is found that the grown crystal has no absorption in the green wavelength region and the SHG efficiency was found to be 2.66 times that of the standard KDP. The Thermal stability of the crystal was found by obtaining TG/DTA curve. The mechanical behavior of the grown crystal has been studied by Vicker's microhardness method.

  10. Large three-dimensional photonic crystals based on monocrystalline liquid crystal blue phases.

    Science.gov (United States)

    Chen, Chun-Wei; Hou, Chien-Tsung; Li, Cheng-Chang; Jau, Hung-Chang; Wang, Chun-Ta; Hong, Ching-Lang; Guo, Duan-Yi; Wang, Cheng-Yu; Chiang, Sheng-Ping; Bunning, Timothy J; Khoo, Iam-Choon; Lin, Tsung-Hsien

    2017-09-28

    Although there have been intense efforts to fabricate large three-dimensional photonic crystals in order to realize their full potential, the technologies developed so far are still beset with various material processing and cost issues. Conventional top-down fabrications are costly and time-consuming, whereas natural self-assembly and bottom-up fabrications often result in high defect density and limited dimensions. Here we report the fabrication of extraordinarily large monocrystalline photonic crystals by controlling the self-assembly processes which occur in unique phases of liquid crystals that exhibit three-dimensional photonic-crystalline properties called liquid-crystal blue phases. In particular, we have developed a gradient-temperature technique that enables three-dimensional photonic crystals to grow to lateral dimensions of ~1 cm (~30,000 of unit cells) and thickness of ~100 μm (~ 300 unit cells). These giant single crystals exhibit extraordinarily sharp photonic bandgaps with high reflectivity, long-range periodicity in all dimensions and well-defined lattice orientation.Conventional fabrication approaches for large-size three-dimensional photonic crystals are problematic. By properly controlling the self-assembly processes, the authors report the fabrication of monocrystalline blue phase liquid crystals that exhibit three-dimensional photonic-crystalline properties.

  11. Growing media [Chapter 5

    Science.gov (United States)

    Douglass F. Jacobs; Thomas D. Landis; Tara Luna

    2009-01-01

    Selecting the proper growing medium is one of the most important considerations in nursery plant production. A growing medium can be defined as a substance through which roots grow and extract water and nutrients. In native plant nurseries, a growing medium can consist of native soil but is more commonly an "artificial soil" composed of materials such as peat...

  12. The Ice Selective Inlet: a novel technique for exclusive extraction of pristine ice crystals in mixed-phase clouds

    Directory of Open Access Journals (Sweden)

    P. Kupiszewski

    2015-08-01

    Full Text Available Climate predictions are affected by high uncertainties partially due to an insufficient knowledge of aerosol–cloud interactions. One of the poorly understood processes is formation of mixed-phase clouds (MPCs via heterogeneous ice nucleation. Field measurements of the atmospheric ice phase in MPCs are challenging due to the presence of much more numerous liquid droplets. The Ice Selective Inlet (ISI, presented in this paper, is a novel inlet designed to selectively sample pristine ice crystals in mixed-phase clouds and extract the ice residual particles contained within the crystals for physical and chemical characterization. Using a modular setup composed of a cyclone impactor, droplet evaporation unit and pumped counterflow virtual impactor (PCVI, the ISI segregates particles based on their inertia and phase, exclusively extracting small ice particles between 5 and 20 μm in diameter. The setup also includes optical particle spectrometers for analysis of the number size distribution and shape of the sampled hydrometeors. The novelty of the ISI is a droplet evaporation unit, which separates liquid droplets and ice crystals in the airborne state, thus avoiding physical impaction of the hydrometeors and limiting potential artefacts. The design and validation of the droplet evaporation unit is based on modelling studies of droplet evaporation rates and computational fluid dynamics simulations of gas and particle flows through the unit. Prior to deployment in the field, an inter-comparison of the optical particle size spectrometers and a characterization of the transmission efficiency of the PCVI was conducted in the laboratory. The ISI was subsequently deployed during the Cloud and Aerosol Characterization Experiment (CLACE 2013 and 2014 – two extensive international field campaigns encompassing comprehensive measurements of cloud microphysics, as well as bulk aerosol, ice residual and ice nuclei properties. The campaigns provided an important

  13. The Ice Selective Inlet: a novel technique for exclusive extraction of pristine ice crystals in mixed-phase clouds

    Science.gov (United States)

    Kupiszewski, P.; Weingartner, E.; Vochezer, P.; Schnaiter, M.; Bigi, A.; Gysel, M.; Rosati, B.; Toprak, E.; Mertes, S.; Baltensperger, U.

    2015-08-01

    Climate predictions are affected by high uncertainties partially due to an insufficient knowledge of aerosol-cloud interactions. One of the poorly understood processes is formation of mixed-phase clouds (MPCs) via heterogeneous ice nucleation. Field measurements of the atmospheric ice phase in MPCs are challenging due to the presence of much more numerous liquid droplets. The Ice Selective Inlet (ISI), presented in this paper, is a novel inlet designed to selectively sample pristine ice crystals in mixed-phase clouds and extract the ice residual particles contained within the crystals for physical and chemical characterization. Using a modular setup composed of a cyclone impactor, droplet evaporation unit and pumped counterflow virtual impactor (PCVI), the ISI segregates particles based on their inertia and phase, exclusively extracting small ice particles between 5 and 20 μm in diameter. The setup also includes optical particle spectrometers for analysis of the number size distribution and shape of the sampled hydrometeors. The novelty of the ISI is a droplet evaporation unit, which separates liquid droplets and ice crystals in the airborne state, thus avoiding physical impaction of the hydrometeors and limiting potential artefacts. The design and validation of the droplet evaporation unit is based on modelling studies of droplet evaporation rates and computational fluid dynamics simulations of gas and particle flows through the unit. Prior to deployment in the field, an inter-comparison of the optical particle size spectrometers and a characterization of the transmission efficiency of the PCVI was conducted in the laboratory. The ISI was subsequently deployed during the Cloud and Aerosol Characterization Experiment (CLACE) 2013 and 2014 - two extensive international field campaigns encompassing comprehensive measurements of cloud microphysics, as well as bulk aerosol, ice residual and ice nuclei properties. The campaigns provided an important opportunity for a

  14. Thermal conductivity prediction of nanoscale phononic crystal slabs using a hybrid lattice dynamics-continuum mechanics technique

    Directory of Open Access Journals (Sweden)

    Charles M. Reinke

    2011-12-01

    Full Text Available Recent work has demonstrated that nanostructuring of a semiconductor material to form a phononic crystal (PnC can significantly reduce its thermal conductivity. In this paper, we present a classical method that combines atomic-level information with the application of Bloch theory at the continuum level for the prediction of the thermal conductivity of finite-thickness PnCs with unit cells sized in the micron scale. Lattice dynamics calculations are done at the bulk material level, and the plane-wave expansion method is implemented at the macrosale PnC unit cell level. The combination of the lattice dynamics-based and continuum mechanics-based dispersion information is then used in the Callaway-Holland model to calculate the thermal transport properties of the PnC. We demonstrate that this hybrid approach provides both accurate and efficient predictions of the thermal conductivity.

  15. Inferences from growing trees backwards

    Science.gov (United States)

    David W. Green; Kent A. McDonald

    1997-01-01

    The objective of this paper is to illustrate how longitudinal stress wave techniques can be useful in tracking the future quality of a growing tree. Monitoring the quality of selected trees in a plantation forest could provide early input to decisions on the effectiveness of management practices, or future utilization options, for trees in a plantation. There will...

  16. Crystal growth and crystallography

    Science.gov (United States)

    Chernov, A. A.

    1998-01-01

    Selected topics that may be of interest for both crystal-structure and crystal-growth communities are overviewed. The growth of protein crystals, along with that of some other compounds, is one of the topics, and recent insights into related phenomena are considered as examples of applications of general principles. The relationship between crystal growth shape and structure is reviewed and an attempt to introduce semiquantitative characterization of binding for proteins is made. The concept of kinks for complex structures is briefly discussed. Even at sufficiently low supersaturations, the fluctuation of steps may not be sufficient to implement the Gibbs-Thomson law if the kink density is low enough. Subsurface ordering of liquids and growth of rough interfaces from melts is discussed. Crystals growing in microgravity from solution should be more perfect if they preferentially trap stress-inducing impurities, thus creating an impurity-depleted zone around themselves. Evidently, such a zone is developed only around the crystals growing in the absence of convection. Under terrestrial conditions, the self-purified depleted zone is destroyed by convection, the crystal traps more impurity and grows stressed. The stress relief causes mosaicity. In systems containing stress-inducing but poorly trapped impurities, the crystals grown in the absence of convection should be worse than those of their terrestrial counterparts.

  17. Fabrication of Y128- and Y36-cut lithium niobate single-crystalline thin films by crystal-ion-slicing technique

    Science.gov (United States)

    Shuai, Yao; Gong, Chaoguan; Bai, Xiaoyuan; Wu, Chuangui; Luo, Wenbo; Böttger, Roman; Zhou, Shengqiang; Tian, Benlang; Zhang, Wanli

    2018-04-01

    Y128- and Y36-cut single-crystalline lithium niobate (LN) thin films are fabricated by the crystal-ion-slicing (CIS) technique onto LN substrates. The conditions for the successful exfoliation of submicron-thick LN thin films are independent of the wafer orientation used in the present work. Wafer bonding using benzocyclobutene (BCB) is adopted to transfer LN thin films onto substrates, instead of the generally used hydrophilic bonding, which does not need a strict surface polishing process before the bonding. A noncontact polishing method involving low-energy Ar+ irradiation is adopted to treat the sliced LN thin films. The atomic force microscopy result shows that the surface roughness of the LN thin film is reduced from 10.6 to 6.4 nm.

  18. Modification of RDX and HMX crystals in procedure of solvent/anti-solvent by statistical methods of Taguchi analysis design and MLR technique

    Directory of Open Access Journals (Sweden)

    Hamid Reza Pouretedal

    2018-02-01

    Full Text Available Many of the physical and functional properties of RDX and HMX explosives are related to the crystalline structure of these materials. Crystalline defects affect the quality of the explosives. Therefore, in order to enhance the quality of these materials, it is necessary to form crystals with the lowest defects. In this research, we report the optimization of recrystallization process of RDX and HMX by statistical techniques. The solvent/anti-solvent procedure was used for recrystallization of HMX and RDX particles. The four parameters of i ratio of anti-solvent to solvent, ii ratio of solute to solvent, iii aging time, and iv cooling rate of mixture, were optimized by Taguchi analysis design. Taguchi L16 orthogonal array was used with sixteen rows corresponding to the number of tests in four columns at four levels. The apparent density of recrystallized of RDX and HMX particles was considered as the quality characteristic with the concept of “the larger-the-better”. The obtained graphs showed that the studied parameters were optimized in ratio 1:1 for anti-solvent to solvent, ratio 0.1 g⋅mL-1 for solute to solvent, aging time of 2 h and cooling rate of 1 °C⋅min-1. Also, the correlation between the investigated parameters and apparent density of crystals were studied by multiple linear regressions (MLR method for obtaining a model of prediction of apparent density. The P-values were indicated that in confidence level of 95%, the null hypothesis is rejected and a meaningful addition is observed in the proposed model.

  19. Experimental observation of the influence of furnace temperature profile on convection and segregation in the vertical Bridgman crystal growth technique

    Science.gov (United States)

    Neugebauer, G. T.; Wilcox, William R.

    1992-01-01

    Azulene-doped naphthalene was directionally solidified during the vertical Bridgman-Stockbarger technique. Doping homogeneity and convection were determined as a function of the temperature profile in the furnace and the freezing rate. Convection velocities were two orders of magnitude lower when the temperature increased with height. Rarely was the convection pattern axisymmetric, even though the temperature varied less than 0.1 K around the circumference of the growth ampoule. Correspondingly the cross sectional variation in azulene concentration tended to be asymmetric, especially when the temperature increased with height. This cross sectional variation changed dramatically along the ingot, reflecting changes in convection presumably due to the decreasing height of the melt. Although there was large scatter and irreproducibility in the cross sectional variation in doping, this variation tended to be least when the growth rate was low and the convection was vigorous. It is expected that compositional variations would also be small at high growth rates with weak convection and flat interfaces, although this was not investigated in the present experiments. Neither rotation of the ampoule nor deliberate introduction of thermal asymmetries during solidification had a significant influence on cross sectional variations in doping. It is predicted that slow directional solidification under microgravity conditions could produce greater inhomogeneities than on Earth. Combined use of microgravity and magnetic fields would be required to achieve homogeneity when it is necessary to freeze slowly in order to avoid constitutional supercooling.

  20. Preparation of TiC single crystals

    International Nuclear Information System (INIS)

    Scheerer, B.; Fink, J.; Reichardt, W.

    1975-07-01

    TiC single crystals were prepared by vertical zone melting for measurements of the phonon dispersion by inelastic neutron scattering. The influence of the starting material and of the growing conditions on the growth of the crystal were studied. The crystals were characterized by chemical methods, EMX and neutron diffraction. It was possible to grow single crystals with a volume of up to 0.6 cm 3 and mosaic spread of less then 0.4 0 . (orig.) [de

  1. Controlling single and few-layer graphene crystals growth in a solid carbon source based chemical vapor deposition

    International Nuclear Information System (INIS)

    Papon, Remi; Sharma, Subash; Shinde, Sachin M.; Vishwakarma, Riteshkumar; Tanemura, Masaki; Kalita, Golap

    2014-01-01

    Here, we reveal the growth process of single and few-layer graphene crystals in the solid carbon source based chemical vapor deposition (CVD) technique. Nucleation and growth of graphene crystals on a polycrystalline Cu foil are significantly affected by the injection of carbon atoms with pyrolysis rate of the carbon source. We observe micron length ribbons like growth front as well as saturated growth edges of graphene crystals depending on growth conditions. Controlling the pyrolysis rate of carbon source, monolayer and few-layer crystals and corresponding continuous films are obtained. In a controlled process, we observed growth of large monolayer graphene crystals, which interconnect and merge together to form a continuous film. On the other hand, adlayer growth is observed with an increased pyrolysis rate, resulting few-layer graphene crystal structure and merged continuous film. The understanding of monolayer and few-layer crystals growth in the developed CVD process can be significant to grow graphene with controlled layer numbers.

  2. Modeling techniques for analysis and interpretation of electron magnetic resonance (EMR) data for transition ions at low symmetry sites in crystals-A primer for experimentalists

    International Nuclear Information System (INIS)

    Rudowicz, Czeslaw; Gnutek, Pawel

    2009-01-01

    Electron magnetic resonance (EMR) studies of paramagnetic centers exhibiting monoclinic and triclinic local site symmetry have gained renewed importance, since such centers occur often in various technologically important materials and biological systems. The intricate low symmetry aspects, which arise for such centers, bear on meaningful interpretation of EMR data and their correlation with structural data. This review provides a primer for experimentalists who wish to utilize efficiently the modeling techniques for analysis and interpretation of EMR data for transition ions, especially ions located at low symmetry sites in crystals. This requires proper understanding of the low symmetry effects observable in EMR spectra as well as related theoretical questions concerning, e.g., (i) existence of physically equivalent zero-field splitting (ZFS) parameter sets, (ii) clear definitions of the axis systems, (iii) proper forms of spin Hamiltonians, and (iv) distinction between apparent and actual low symmetry cases. The question (i) involves consideration of the orthorhombic standardization, which provides basis for standardization of monoclinic and triclinic ZFS parameters. Thus, the aspects pertaining to orthorhombic site symmetry are also outlined. To solve other questions several modeling techniques have been utilized and related computer packages have recently been developed in our group: (1) the superposition model calculations of the zero-field splitting parameters (ZFSPs) in arbitrary symmetry, (2) the procedure for diagonalization of the 2nd-rank ZFSPs and transformation of respective 4th- and 6th-rank ZFSPs, (3) the pseudosymmetry axes method for approximation of the 4th- and 6th-rank ZFSPs to higher symmetry, and (4) the closeness factors and norm ratios for quantitative comparisons of various ZFSP sets. These modeling techniques enable deeper analysis and interpretation of the low symmetry aspects involved in the fitted and theoretical ZFSPs. The computer

  3. Crystal face temperature determination means

    Science.gov (United States)

    Nason, D.O.; Burger, A.

    1994-11-22

    An optically transparent furnace having a detection apparatus with a pedestal enclosed in an evacuated ampule for growing a crystal thereon is disclosed. Temperature differential is provided by a source heater, a base heater and a cold finger such that material migrates from a polycrystalline source material to grow the crystal. A quartz halogen lamp projects a collimated beam onto the crystal and a reflected beam is analyzed by a double monochromator and photomultiplier detection spectrometer and the detected peak position in the reflected energy spectrum of the reflected beam is interpreted to determine surface temperature of the crystal. 3 figs.

  4. Crystal structure analysis in solution-processed uniaxially oriented polycrystalline thin film of non-peripheral octahexyl phthalocyanine by grazing incidence wide-angle x-ray scattering techniques

    Science.gov (United States)

    Ohmori, Masashi; Uno, Takashi; Nakatani, Mitsuhiro; Nakano, Chika; Fujii, Akihiko; Ozaki, Masanori

    2016-10-01

    Uniaxially oriented thin films of metal-free non-peripherally octahexyl-substituted phthalocyanine (C6PcH2), which exhibits high carrier mobility, have been fabricated by the bar-coating technique, which is a simple solution process. The molecular orientation and molecular steps in the thin film were observed by the polarized spectroscopy and the atomic force microscopy, respectively. The three-dimensional molecular packing structure in the thin film was investigated by the grazing incidence wide-angle X-ray scattering technique with an in-plane sample rotation. The crystal orientation was clarified, and the three-dimensional molecular packing structure of the thin film was found to match the single crystal structure. Moreover, the X-ray diffraction patterns of the oriented thin films were simulated by using the lattice parameters of C6PcH2 single crystal to reproduce the observed X-ray diffraction patterns.

  5. Ultraslow growth rates of giant gypsum crystals

    Science.gov (United States)

    Van Driessche, A. E. S.; García-Ruíz, J. M.; Tsukamoto, K.; Patiño-Lopez, L. D.; Satoh, H.

    2011-01-01

    Mineralogical processes taking place close to equilibrium, or with very slow kinetics, are difficult to quantify precisely. The determination of ultraslow dissolution/precipitation rates would reveal characteristic timing associated with these processes that are important at geological scale. We have designed an advanced high-resolution white-beam phase-shift interferometry microscope to measure growth rates of crystals at very low supersaturation values. To test this technique, we have selected the giant gypsum crystals of Naica ore mines in Chihuahua, Mexico, a challenging subject in mineral formation. They are thought to form by a self-feeding mechanism driven by solution-mediated anhydrite-gypsum phase transition, and therefore they must be the result of an extremely slow crystallization process close to equilibrium. To calculate the formation time of these crystals we have measured the growth rates of the {010} face of gypsum growing from current Naica waters at different temperatures. The slowest measurable growth rate was found at 55 °C, 1.4 ± 0.2 × 10-5 nm/s, the slowest directly measured normal growth rate for any crystal growth process. At higher temperatures, growth rates increase exponentially because of decreasing gypsum solubility and higher kinetic coefficient. At 50 °C neither growth nor dissolution was observed indicating that growth of giant crystals of gypsum occurred at Naica between 58 °C (gypsum/anhydrite transition temperature) and the current temperature of Naica waters, confirming formation temperatures determined from fluid inclusion studies. Our results demonstrate the usefulness of applying advanced optical techniques in laboratory experiments to gain a better understanding of crystal growth processes occurring at a geological timescale. PMID:21911400

  6. Crystal-growth Underground Breeding Extra-sensitive Detectors

    Science.gov (United States)

    Mei, Dongming

    2012-02-01

    CUBED (Center for Ultra-Low Background Experiments at DUSEL) collaborators from USD, SDSMT, SDSU, Sanford Lab, and Lawrence Berkeley National Laboratory are working on the development of techniques to manufacture crystals with unprecedented purity levels in an underground environment that may be used by experiments proposed for DUSEL. The collaboration continues to make significant progress toward its goal of producing high purity germanium crystals. High quality crystals are being pulled on a weekly basis at the temporary surface growth facility located on the USD campus. The characterization of the grown crystals demonstrates that the impurity levels are nearly in the range of the needed impurity level for detector-grade crystals. Currently, the crystals are being grown in high-purity hydrogen atmosphere. With an increase in purity due to the zone refining, the group expects to grow high-purity crystals by the end of 2011. The one third of the grown crystals will be manufactured to be detectors; the remaining will be fabricated in to wafers that have large applications in electro and optical devices as well as solar panels. This would allow the research to be connected to market and create more than 30 jobs and multi millions revenues in a few years.

  7. Growing Vertical in the Flatland.

    Science.gov (United States)

    Robinson, Joshua A

    2016-01-26

    The world of two-dimensional (2D) heterostructures continues to expand at a rate much greater than anyone could have predicted 10 years ago, but if we are to make the leap from science to technology, many materials challenges must still be overcome. Recent advances, such as those by Liu et al. in this issue of ACS Nano, demonstrate that it is possible to grow rotationally commensurate 2D heterostructures, which could pave the way toward single crystal van der Waals solids. In this Perspective, I provide some insight into a few of the challenges associated with growth of heterostructures, and discuss some of the recent works that help us better understand synthetic realization of 2D heterostructures.

  8. Crystal growth and physical properties of Ferro-pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Aswartham, Saicharan

    2012-11-08

    The thesis work presented here emphasizes important aspects of crystal growth and the influence of chemical substitution in Fe-As superconductors. High temperature solution growth technique is one of most powerful and widely used technique to grow single crystals of various materials. The biggest advantage of high temperature solution growth technique is the, possibility of growing single crystals from both congruently and incongruently melting materials. Solution growth technique has the potential to control high vapour pressures, given the fact that, in Fe-based superconductors elements with high vapour pressure like As, K, Li and Na have to be handled during the crystal growth procedure. In this scenario high temperature solution growth is the best suitable growth technique to synthesize sizable homogeneous single crystals. Using self-flux high temperature solution growth technique, large centimeter-sized high quality single crystals of BaFe{sub 2}As{sub 2} were grown. This pristine compound BaFe{sub 2}As{sub 2} undergoes structural and magnetic transition at T{sub S/N} = 137 K. By suppressing this magnetic transition and stabilizing tetragonal phase with chemical substitution, like Co-doping and Na-doping, bulk superconductivity is achieved. Superconducting transitions of as high as T{sub c} = 34 K with Na substitution and T{sub c} = 25 K with Co-doping were obtained. A combined electronic phase diagram has been achieved for both electron doping with Co and hole doping with Na in BaFe{sub 2}As{sub 2}. Single crystals of LiFe{sub 1-x}Co{sub x}As with x = 0, 0.025, 0.05 and 0.075 were grown by a self-flux high temperature solution growth technique. The charge doping in LiFeAs is achieved with the Co-doping in Fe atoms. The superconducting properties investigated by means of temperature dependent magnetization and resistivity revealed that superconductivity is shifted to lower temperatures and with higher amount of charge carriers superconductivity is killed

  9. Lysozyme crystal growth, as observed by small angle X-ray scattering, proceeds without crystallization intermediates

    International Nuclear Information System (INIS)

    Finet, S.; Bonnete, F.; Frouin, J.; Provost, K.; Tardieu, A.

    1998-01-01

    A combination of small angle X-ray scattering and gel techniques was used to follow the kinetics of protein crystal growth as a function of time. Hen egg white lysozyme, at different protein concentrations, was used as a model system. A new sample holder was designed, in which supersaturation is induced in the presence of salt by decreasing the temperature. It had been shown previously that a decrease in temperature and/or an increase in crystallizing agent induces an increase in the attractive interactions present in the lysozyme solutions, the lysozyme remaining monomeric. In the present paper we show that similar behaviour is observed in NaCl when agarose gels are used. During crystal growth, special attention was paid to determine whether oligomers were formed as the protein in solution was incorporated in the newly formed crystals. From these first series of experiments, we did not find any indication of oligomer formation between monomer in solution and crystal. The results obtained are in agreement with the hypothesis that lysozyme crystals in NaCl grow by addition of monomeric particles. (orig.)

  10. On-Line Measurement of The Shape and Growth Rates of Organic Crystals in Reactors: Advances and Perspectives for Control

    International Nuclear Information System (INIS)

    Wang, Xue Z.

    2007-01-01

    Organic crystals grown from solution are known to exhibit multiple morphology and habits which are of great importance to the end use property of the product such as the bioavailability and down stream processing such as in filtration and drying. The crystal morphology can also dictate other quality measures such as the size. This paper reviews recent developments in on-line crystal morphology measurement and control using various techniques including on-line imaging and image analysis, and XRD. On-line imaging was found to be the most promising technique in capturing with high fidelity crystal shape and polymorphic transitions in real-time. Process in imaging and image analysis techniques will also be reviewed for extracting the crystals from the image background especially for images with uneven background intensity, of needle-like crystals and of high concentration slurries. Discussion will be given to shape descriptors and automatic shape recognition. Preliminary results and challenges for estimating crystal growth rates and kinetics parameters for different crystal facets will also be discussed. Future research directions for obtaining 3D instead of 2D dimensional information using imaging and image analysis techniques will be explored. Finally a framework integrating morphology modeling, multi-dimensional population balance and computational fluid dynamics, with 3D imaging and image analysis will be presented which provides the basis for model predictive automatic control of the morphology of growing crystals

  11. 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...... of the zeolite particles, particularly after thermal treatment. When using mesoporous zeolites, the particles were evenly distributed throughout the mesopore system of the zeolitic support, even after calcination, leading to nanocrystals within mesoporous zeolite single crystals....

  12. Evaluating the Effect of Surface Roughness on Titanium Dioxide Nanoparticle Deposition using a Combined Quartz Crystal Microbalance with Dissipation (QCM-D) and Generalized Ellipsometry (GE) Technique

    Science.gov (United States)

    Kananizadeh, N.; Lee, J.; Rodenhausen, K. B.; Sekora, D.; Schubert, M.; Schubert, E.; Bartelt-Hunt, S.; Li, Y.

    2016-12-01

    Quantification and characterization of nanoparticles in soils and sediments are very challenging because they will interact not only with soil-water chemistry but also with highly heterogeneous soil and sediment surfaces. In this work, we measured the interaction of Titanium dioxide nanoparticles (nTiO2), the most extensively manufactured engineered materials, with engineered rough surfaces under varied ionic strength conditions. Innovative three-dimensional Silicon nanostructured surfaces, referred to here as slanted columnar thin films (SCTFs), were used to generate surface roughness with controlled heights of 50nm, 100nm, and 200nm. Using atomic layer deposition technique (ALD), surfaces of SCTF were coated with either silicon dioxide or aluminum oxides to represent the most abundant silica aquifer materials and metal oxide impurities, respectively. The interaction between nTiO2 and model rough surfaces was measured using quartz crystal microbalance with dissipation monitoring (QCM-D). The data were analyzed using a model that couples the viscoelastic effect with the surface roughness effect. No nTiO2 deposition was observed on neither flat nor rough silicon dioxide surfaces under ionic strength ranged from 0 to 100 mM NaCl. On the other hand, the deposition of nTiO2 on the aluminum oxides coated surfaces increased as the height of roughness increased. In parallel with QCM-D, a Generalized Ellipsometry (GE) was used to measure the mass of deposited nTiO2. The combination of QCM-D and GE revealed that the properties (i.e. porosity and rigidness) of attached nTiO2 layer on the QCM-D surfaces were dependent on ionic strength and surface roughness.

  13. Growth patterns of monosodium urate monohydrate (gouty and urinary) crystals in gel: An in vitro study.

    Science.gov (United States)

    Ahmed, Salman; Hasan, Muhammad Mohtasheemul; Mahmood, Zafar Alam

    2017-11-01

    Monosodium urate monohydrate crystals are deposited in peripheral joints causing gout and elicit an intense localized inflammatory attack whereas in collecting ducts and medullary interstitium as a urinary calculi which causes dysuria, nausea and hematuria. The purpose of present study is to observe possible growth patterns of monosodium urate monohydrate crystals. The crystals were grown in test tubes by single diffusion gel technique and were observed at 7th, 14th, 21st, 28th and 40th day. Needle and spherulite type crystals were observed at 14th day, while arboresque, crystal sheaves, densely branched, dumbbell, mushroom type spherulites, plumose and hexagonal prismatic crystals were observed for the first time. After 40th day complete spherulites were observed with their aggregates. The crystals were characterized by Scanning Electron Microscopy, Energy-Dispersive X-ray and Fourier Transform infra Red spectroscopies. The pattern of MSUM will be helpful to determine the role of different natural products in the modulation, inhibition or promotion of these crystals by affecting the shape, size, transparency, approximate number and total mass of growing crystals. In case of inhibition or modulation it will be helpful for evaluation the prophylactic management whereas the promotion of the crystal will give an idea about the risk factors of gout and kidney stones.

  14. The fluid phenomena in the crystallization of the protein crystal

    International Nuclear Information System (INIS)

    Duan Li; Kang Qi

    2008-01-01

    This paper reports that an optical diagnostic system consisting of Mach–Zehnder interferometer with a phase shift device and image processor has been used for study of the kinetics of protein crystal growing process. The crystallization process of protein crystal by vapour diffusion is investigated. The interference fringes are observed in real time. The present experiment demonstrates that the diffusion and the sedimentation influence the crystallization of protein crystal which grows in solution, and the concentration capillary convection associated with surface tension occurs at the vicinity of free surface of the protein mother liquor, and directly affects on the outcome of protein crystallization. So far the detailed analysis and the important role of the fluid phenomena in protein crystallization have been discussed a little in both space- and ground-based crystal growth experiments. It is also found that these fluid phenomena affect the outcome of protein crystallization, regular growth, and crystal quality. This may explain the fact that many results of space-based investigation do not show overall improvement. (cross-disciplinary physics and related areas of science and technology)

  15. Preparation of fine single crystals of magnetic superconductor RuSr2GdCu2O8‑δ by partial melting

    Science.gov (United States)

    Yamaki, Kazuhiro; Bamba, Yoshihiro; Irie, Akinobu

    2018-03-01

    In this study, fine uniform RuSr2GdCu2O8‑δ (RuGd-1212) single crystals have been successfully prepared by partial melting. Synthesis temperature could be lowered to a value not exceeding the decomposition temperature of RuGd-1212 using the Sr–Gd–Cu–O flux. The crystals grown by alumina boats are cubic, which coincides with the result of a previous study of RuGd-1212 single crystals using platinum crucibles. The single crystals were up to 15 × 15 × 15 µm3 in size and their lattice constants were consistent with those of polycrystalline samples reported previously. Although the present size of single crystals is not sufficient for measurements, the partial melting technique will be beneficial for future progress of research using RuGd-1212 single crystals. Appropriate nominal composition, sintering atmosphere, and temperature are essential factors for growing RuGd-1212 single crystals.

  16. WHEN COMPASSION GROWS WINGS

    African Journals Online (AJOL)

    Nicky

    antiretroviral roll-out in full swing, the. WHEN COMPASSION GROWS WINGS. The free time and expertise given by its deeply committed core of professional volunteers. (including pilots) is the lifeblood of the operation. Red Cross Air Mercy Service volunteer, German national Dr Florian Funk, at the AMS Durban base.

  17. Growing Plants and Minds

    Science.gov (United States)

    Presser, Ashley Lewis; Kamdar, Danae; Vidiksis, Regan; Goldstein, Marion; Dominguez, Ximena; Orr, Jillian

    2017-01-01

    Many preschool classrooms explore plant growth. However, because many plants take a long time to grow, it is often hard to facilitate engagement in some practices (i.e., since change is typically not observable from one day to another, children often forget their prior predictions or cannot recall what plants looked like days or weeks earlier).…

  18. Crystallography, magnetic susceptibility, heat capacity, and electrical resistivity of heavy-fermion LiV2O4 single crystals grown using a self-flux technique

    Science.gov (United States)

    Das, S.; Zong, X.; Niazi, A.; Ellern, A.; Yan, J. Q.; Johnston, D. C.

    2007-08-01

    Magnetically pure spinel compound LiV2O4 is a rare d -electron heavy fermion. Measurements on single crystals are needed to clarify the mechanism for the heavy-fermion behavior in the pure material. In addition, it is known that small concentrations (<1mol%) of magnetic defects in the structure strongly affect the properties, and measurements on single crystals containing magnetic defects would help to understand the latter behaviors. Herein, we report flux growth of LiV2O4 and preliminary measurements to help resolve these questions. The magnetic susceptibility of some as-grown crystals show a Curie-like upturn at low temperatures, showing the presence of magnetic defects within the spinel structure. The magnetic defects could be removed in some of the crystals by annealing them at 700°C . A very high specific heat coefficient γ=450mJ/molK2 was obtained at a temperature of 1.8K for a crystal containing a magnetic defect concentration ndefect=0.5mol% . A crystal with ndefect=0.01mol% showed a residual resistivity ratio of 50.

  19. Imaging of domains in single crystals of BiFeO3-PbTiO3 using various microscopy techniques

    Science.gov (United States)

    Burnett, T. L.; Comyn, T. P.; Bell, A. J.; Condliffe, E.; Lloyd, G.

    2006-02-01

    Single crystals of BiFeO3-PbTiO3 have been grown from a PbO:Bi2O3 flux by cooling at a rate of 2°C/hour from the melt. Faceted crystals of various morphologies were produced and the size of the crystals ranged from less than 0.5mm to 5mm. Initial measurements were made using the scanning electron microscope (SEM) with energy dispersive X-ray analysis (EDX) semi-quantifying the composition of the crystals as well as electron probe microanalysis (EPMA). Powder X-ray diffraction (XRD) of the crushed and sieved crystals established that the structure was rhombohedral perovskite for the (BiFeO3)0.75-(PbTiO3)0.25 composition and tetragonal perovskite for the (BiFeO3)0.50-(PbTiO3)0.50 composition and mixed phase for the (BiFeO3)0.65-(PbTiO3)0.35 and (BiFeO3)0.70- (PbTiO3)0.30. X-ray pole figures verified that the (BiFeO3)0.75-(PbTiO3)0.25 crystal had grown with a single orientation, the [100] direction. Structures that are believed to be domains have been observed through optical and electron microscopy in backscattered mode. This interim report of on going investigations seeks to eventually confirm the domain structure in the crystals with electron back-scattered diffraction (EBSD).

  20. Growing up with Retinoblastoma

    Science.gov (United States)

    Maley, Tom

    2005-01-01

    An account is given of growing up as a child blinded as a result of a cancer of the eye known as retinoblastoma. The role of his mother is brought out, variously as a source of objective knowledge, of one's personal worth, and of the worth of other people in one's community. The strengths and weaknesses of his first school in his home area and…

  1. Quartz crystal growth

    Science.gov (United States)

    Baughman, Richard J.

    1992-01-01

    A process for growing single crystals from an amorphous substance that can undergo phase transformation to the crystalline state in an appropriate solvent. The process is carried out in an autoclave having a lower dissolution zone and an upper crystallization zone between which a temperature differential (.DELTA.T) is maintained at all times. The apparatus loaded with the substance, solvent, and seed crystals is heated slowly maintaining a very low .DELTA.T between the warmer lower zone and cooler upper zone until the amorphous substance is transformed to the crystalline state in the lower zone. The heating rate is then increased to maintain a large .DELTA.T sufficient to increase material transport between the zones and rapid crystallization. .alpha.-Quartz single crystal can thus be made from fused quartz in caustic solvent by heating to 350.degree. C. stepwise with a .DELTA.T of 0.25.degree.-3.degree. C., increasing the .DELTA.T to about 50.degree. C. after the fused quartz has crystallized, and maintaining these conditions until crystal growth in the upper zone is completed.

  2. 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.

  3. The Effect of Solution Conditions on the Nucleation Kinetics of Tetragonal Lysozyme Crystals

    Science.gov (United States)

    Judge, Russell A.; Baird, James K.; Pusey, Marc L.

    1998-01-01

    An understanding of protein crystal nucleation rates and the effect of solution conditions upon them, is fundamental to the preparation of protein crystals of the desired size and shape for X-ray diffraction analysis. The ability to predict the effect of supersaturation, temperature, pH and precipitant concentration on the number and size of crystals formed is of great benefit in the pursuit of protein structure analysis. In this study we experimentally examine the effect of supersaturation, temperature, pH and sodium chloride concentration on the nucleation rate of tetragonal chicken egg white lysozyme crystals. In order to do this batch crystallization plates were prepared at given solution concentrations and incubated at three different temperatures over the period of one week. The number of crystals per well with their size and dimensions were recorded and correlated against solution conditions. Duplicate experiments indicate the reproducibility of the technique. Although it is well known that crystal numbers increase with increasing supersaturation, large changes in crystal number were also correlated against solution conditions of temperature, pH and salt concentration over the same supersaturation ranges. Analysis of these results enhance our understanding of the effect of solution conditions such as the dramatic effect that small changes in charge and ionic strength can have on the number of tetragonal lysozyme crystals that form and grow in solution.

  4. Raman, AFM and SNOM high resolution imaging of carotene crystals in a model carrot cell system.

    Science.gov (United States)

    Rygula, Anna; Oleszkiewicz, Tomasz; Grzebelus, Ewa; Pacia, Marta Z; Baranska, Malgorzata; Baranski, Rafal

    2018-05-15

    Three non-destructive and complementary techniques, Raman imaging, Atomic Force Microscopy and Scanning Near-field Optical Microscopy were used simultaneously to show for the first time chemical and structural differences of carotenoid crystals. Spectroscopic and microscopic scanning probe measurements were applied to the released crystals or to crystals accumulated in a unique, carotenoids rich callus tissue growing in vitro that is considered as a new model system for plant carotenoid research. Three distinct morphological crystal types of various carotenoid composition were identified, a needle-like, rhomboidal and helical. Raman imaging using 532 and 488 nm excitation lines provided evidence that the needle-like and rhomboidal crystals had similar carotenoid composition and that they were composed mainly of β-carotene accompanied by α-carotene. However, the presence of α-carotene was not identified in the helical crystals, which had the characteristic spatial structure. AFM measurements of crystals identified by Raman imaging revealed the crystal topography and showed the needle-like and rhomboidal crystals were planar but they differed in all three dimensions. Combining SNOM and Raman imaging enabled indication of carotenoid rich structures and visualised their distribution in the cell. The morphology of identified subcellular structures was characteristic for crystalline, membraneous and tubular chromoplasts that are plant organelles responsible for carotenoid accumulation in cells. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Scanning electron microscope view of iron crystal

    Science.gov (United States)

    1972-01-01

    A scanning electron microscope photograph of iron crystals which grow in a small vug or cavity in a recrystallized breccia (fragmented rock) from the Apollo 15 Hadley-Apennino lunar landing site. The largest crystal is three microns across. Perfectly developed crystals such as these indicate slow formation from a hot vapor as the rock was cooling. The crystals are resting on an interlocking lattice of pyroxene (calsium-magnesium-iron silicate).

  6. Further progress in lead tungstate crystals

    International Nuclear Information System (INIS)

    Fyodorov, A.; Korzhik, M.; Missevitch, O.; Pavlenko, V.; Kachanov, V.; Singovsky, A.; Annenkov, A.N.; Ligun, V.A.; Peigneux, J.P.; Vialle, J.P.

    1994-12-01

    Lead tungstate (PbWO 4 ) called PWO crystal is considered as a promising material for precise electromagnetic calorimetry. It is shown that the tuning of the growing conditions improved the uniformity of the stoichiometric PWO crystal. Crystals grown with Nb doping show improved transmission below 400 nm and, by controlling the occurrence of the defect in the crystal based on Pb 3+ ions, their radiation hardness is increased significantly. (K.A.). 10 refs., 10 figs., 2 tabs

  7. A Few Good Crystals Please

    Science.gov (United States)

    Judge, Russell A.; Snell, Edward H.

    1999-01-01

    Part of the challenge of macromolecular crystal growth for structure determination is obtaining an appropriate number of crystals with a crystal volume suitable for X-ray analysis. In this respect an understanding of the effect of solution conditions on macromolecule nucleation rates is advantageous. This study investigated the effects of solution conditions on the nucleation rate and final crystal size of two crystal systems; tetragonal lysozyme and glucose isomerase. Batch crystallization plates were prepared at given solution concentration and incubated at set temperatures over one week. The number of crystals per well with their size and axial ratios were recorded and correlated with solution conditions. Duplicate experiments indicate the reproducibility of the technique. Results for each system showing the effect of supersaturation, incubation temperature and solution pH on nucleation rates will be presented and discussed. In the case of lysozyme, having optimized solution conditions to produce an appropriate number of crystals of a suitable size, a batch of crystals were prepared under exactly the same conditions. Fifty of these crystals were analyzed by x-ray techniques. The results indicate that even under the same crystallization conditions, a marked variation in crystal properties exists.

  8. Hydrothermal crystal growth of oxides for optical applications

    Science.gov (United States)

    McMillen, Colin David

    2007-12-01

    The manipulation of light has proven to be an integral part of today's technology-based society. In particular, there is great interest in obtaining coherent radiation in all regions of the optical spectrum to advance technology in military, medical, industrial, scientific and consumer fields. Exploring new crystal growth techniques as well as the growth of new optical materials is critical in the advancement of solid state optics. Surprisingly, the academic world devotes little attention to the growth of large crystals. This shortcoming has left gaps in the optical spectrum inaccessible by solid state devices. This dissertation explores the hydrothermal crystal growth of materials that could fill two such gaps. The first gap exists in the deep-UV region, particularly below 200 nm. Some materials such as LiB3O5 and beta-BaB2O4 can generate coherent light at wavelengths as low as 205 nm. The growth of these materials was explored to investigate the feasibility of the hydrothermal method as a new technique for growing these crystals. Particular attention was paid to the descriptive chemistry surrounding these systems, and several novel structures were elucidated. The study was also extended to the growth of materials that could be used for the generation of coherent light as low as 155 nm. Novel synthetic schemes for Sr2Be2B2O7 and KBe2BO 3F2 were developed and the growth of large crystals was explored. An extensive study of the structures, properties and crystal growth of related compounds, RbBe2BO3F2 and CsBe2BO 3F2, was also undertaken. Optimization of a number of parameters within this family of compounds led to the hydrothermal growth of large, high quality single crystal at rates suitable for large-scale growth. The second gap in technology is in the area of high average power solid state lasers emitting in the 1 mum and eye-safe (>1.5 mum) regions. A hydrothermal technique was developed to grow high quality crystals of Sc 2O3 and Sc2O3 doped with suitable

  9. Analysis of spin-Hamiltonian and molecular orbital coefficients of Cu2+ doped C8H11KO8 single crystal through EPR technique

    Science.gov (United States)

    Juliet sheela, K.; Krishnan, S. Radha; Shanmugam, V. M.; Subramanian, P.

    2018-04-01

    Electron paramagnetic resonance (EPR) studies have been investigated at X-band microwave frequency on Cu2+ ion incorporated into the single crystal of potassium succinate-succinic acid (KSSA) at room temperature. The angular variation of the EPR spectra has shown two magnetically in-equivalent Cu2+ sites in the KSSA single crystal system. The spin Hamiltonian parameters g and A are determined which reveals that the site I and site II occupied in rhombic and axial local field symmetry around the impurity ion. Among the two paramagnetic impurity ions, sites one occupies at substituitional position in the place of monovalent cation (K+) in the crystal whereas the other enters in its lattice interstitially by the correlation of EPR and crystal structure data. From the calculated principle values gxx, gyy, gzz and Axx, Ayy, Azz of both the sites, the admixture coefficients and molecular orbital coefficients were evaluated which gives the information of ground state wave function and types of bonding of impurity ions with the ligands.

  10. Beam tests of proton-irradiated PbWO$_4$ crystals and evaluation of double-sided read-out technique for mitigation of radiation damage effects

    CERN Document Server

    Lucchini, Marco Toliman

    2016-01-01

    The harsh radiation environment in which detectors will have to operate during the High Luminosity phase of the LHC (HL-LHC) represents a crucial challenge for many calorimeter technologies. In the CMS forward calorimeters, ionizing doses and hadron fluences will reach up to 300 kGy (at a dose rate of 30 Gy/h) and $2\\times10^{14}$ cm$^{-2}$, respectively, at the pseudorapidity region of $\\lvert \\eta\\rvert=2.6$. To evaluate the evolution of the CMS ECAL performance in such conditions, a set of PbWO$_4$ crystals, exposed to 24 GeV protons up to integrated fluences between $2.1\\times10^{13}$ cm$^{-2}$ and $1.3\\times10^{14}$ cm$^{-2}$, has been studied in beam tests. A degradation of the energy resolution and a non-linear response to electron showers are observed in damaged crystals. Direct measurements of the light output from the crystals show the amplitude decreasing and pulse becoming faster as the fluence increases. The evolution of the performance of the PbWO$_4$ crystals has been well understood and parame...

  11. Czochralski growth of gallium indium antimonide alloy crystals

    Energy Technology Data Exchange (ETDEWEB)

    Tsaur, S.C.

    1998-02-01

    Attempts were made to grow alloy crystals of Ga{sub 1{minus}x}In{sub x}Sb by the conventional Czochralski process. A transparent furnace was used, with hydrogen purging through the chamber during crystal growth. Single crystal seeds up to about 2 to 5 mole% InSb were grown from seeds of 1 to 2 mole% InSb, which were grown from essentially pure GaSb seeds of the [111] direction. Single crystals were grown with InSb rising from about 2 to 6 mole% at the seed ends to about 14 to 23 mole% InSb at the finish ends. A floating-crucible technique that had been effective in reducing segregation in doped crystals, was used to reduce segregation in Czochralski growth of alloy crystals of Ga{sub 1{minus}x}In{sub x}Sb. Crystals close to the targeted composition of 1 mole% InSb were grown. However, difficulties were encountered in reaching higher targeted InSb concentrations. Crystals about 2 mole% were grown when 4 mole% was targeted. It was observed that mixing occurred between the melts rendering the compositions of the melts; and, hence, the resultant crystal unpredictable. The higher density of the growth melt than that of the replenishing melt could have triggered thermosolutal convection to cause such mixing. It was also observed that the floating crucible stuck to the outer crucible when the liquidus temperature of the replenishing melt was significantly higher than that of the growth melt. The homogeneous Ga{sub 1{minus}x}In{sub x}Sb single crystals were grown successfully by a pressure-differential technique. By separating a quartz tube into an upper chamber for crystal growth and a lower chamber for replenishing. The melts were connected by a capillary tube to suppress mixing between them. A constant pressure differential was maintained between the chambers to keep the growth melt up in the growth chamber. The method was first tested with a low temperature alloy Bi{sub 1{minus}x}Sb{sub x}. Single crystals of Ga{sub 1{minus}x}In{sub x}Sb were grown with uniform

  12. 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)

  13. Crystal Engineering

    Indian Academy of Sciences (India)

    Nangia (2002). “Today, research areas under the wide umbrella of crystal engineering include: supramolecular synthesis; nanotechnology; separation science and catalysis; supramolecular materials and devices; polymorphism; cocrystals, crystal structure prediction; drug design and ligand–protein binding.”

  14. Growth and characterization of nonlinear optical single crystals: bis ...

    Indian Academy of Sciences (India)

    methoxy benzoate (C4MB) single crystals were successfully grown by the slow evaporation solution growth technique. The harvested crystals were subjected to single-crystal X-ray diffraction, spectral, optical, thermal and mechanical studies in ...

  15. Growing Data User Communities

    Science.gov (United States)

    Wiggin, B.

    2017-12-01

    Preserving data is not only a technical challenge. Perhaps the best way to protect data is to use it. Grassroots efforts to make research-quality copies of federal data continue to energize communities of data users who often did not previously recognize themselves as open earth data users. Beyond "data rescue" events, the Data Refuge project researches how federal climate and environmental data are used downstream in a variety of local communities and municipal governments to address everyday issues: public health, municipal safety, and even the preservation of cultural heritage assets. Documenting the diverse uses made of open earth data beyond the earth sciences research community grows the community who, in making use of data, also helps to preserve it.

  16. Growing a market economy

    Energy Technology Data Exchange (ETDEWEB)

    Basu, N.; Pryor, R.J.

    1997-09-01

    This report presents a microsimulation model of a transition economy. Transition is defined as the process of moving from a state-enterprise economy to a market economy. The emphasis is on growing a market economy starting from basic microprinciples. The model described in this report extends and modifies the capabilities of Aspen, a new agent-based model that is being developed at Sandia National Laboratories on a massively parallel Paragon computer. Aspen is significantly different from traditional models of the economy. Aspen`s emphasis on disequilibrium growth paths, its analysis based on evolution and emergent behavior rather than on a mechanistic view of society, and its use of learning algorithms to simulate the behavior of some agents rather than an assumption of perfect rationality make this model well-suited for analyzing economic variables of interest from transition economies. Preliminary results from several runs of the model are included.

  17. Growing Old in Exile

    DEFF Research Database (Denmark)

    Liversage, Anika; Mirdal, Gretty Mizrahi

    2017-01-01

    Some studies on immigrants and ageing focus on the question of return; others focus on how immigrants, who grow old in their countries of destination, ‘age in place’, including whether they turn to their children or to public host country provisions for care and support. However, the issues...... of return and of ageing in place may both hold significance in individual immigrants’ lives. To investigate the changing expectations of old age throughout the life course, this paper draws on longitudinal interviews with immigrant women from Turkey who live in Denmark. We focus on the function of proximity...... to children. Using two women who were interviewed three times over three decades as case studies, the analysis shows that in the middle of life, the women share expectations of returning to Turkey, but these plans are perpetually postponed. As the women age, they must face their inability to leave...

  18. The growing fibroadenoma

    International Nuclear Information System (INIS)

    Sanders, Linda M; Sara, Rana

    2015-01-01

    Fibroadenomas (FAs) are the most common tumors of the breast clinically and pathologically in adolescent and young women but may be discovered at any age. With increasing use of core biopsy rather than excision for diagnosis, it is now commonplace to follow these lesions with imaging. To assess the incidence of epithelial abnormalities (atypia, in situ or invasive, ductal or lobular malignancies) in FAs diagnosed by core biopsy and to re-evaluate the management paradigm for any growing FA. A retrospective review of the senior author’s pathology results over 19 years identified 2062 nodular FAs (biopsied by ultrasound or stereotactic guidance). Eighty-three core biopsied FAs were identified which subsequently enlarged. Twelve of 2062 of core biopsied nodules demonstrated atypia, in situ, or invasive malignancy (ductal or lobular) within or adjacent to the FA (0.58%). Eighty-three FAs enlarged and underwent either surgical excision (n = 65), repeat core biopsy (n = 9), or imaging follow-up (n = 9). The incidence of atypia, in situ or invasive malignancy was 0/83 (0%). Two enlarging FAs were subsequently surgically diagnosed as benign phyllodes tumors (PT). Malignancy in or adjacent to a core biopsied FA is rare. The risk of cancer in a growing FA is even rarer; none were present in our series. FAs with abnormal epithelial abnormalities require excision. Otherwise, FAs without epithelial abnormality diagnosed by core biopsy need no specific follow-up considering the negligible incidence of conversion to malignancy. The breast interventionalist must know how to manage discordant pathology results

  19. Growth of single crystals of BaFe12O19 by solid state crystal growth

    International Nuclear Information System (INIS)

    Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

    2016-01-01

    Single crystals of BaFe 12 O 19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe 12 O 19 are buried in BaFe 12 O 19 +1 wt% BaCO 3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe 12 O 19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe 12 O 19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth. - Highlights: • Single crystals of BaFe 12 O 19 are grown by solid state crystal growth. • A single crystal up to ∼130 μm thick (c-axis direction) grows on the seed crystal. • The single crystal and surrounding ceramic matrix have similar composition. • Micro-Raman scattering shows the single crystal has the BaFe 12 O 19 structure.

  20. Expression, purification, crystallization and preliminary X-ray analysis of Escherichia coli 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase.

    Science.gov (United States)

    Lee, J E; Cornell, K A; Riscoe, M K; Howell, P L

    2001-01-01

    A recombinant form of Escherichia coli 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase (E.C. 3.2.2.9) has been purified to homogeneity and crystallized using the hanging-drop vapour-diffusion technique. While several different crystallization conditions were obtained, only one set of conditions yielded crystals suitable for X-ray diffraction analysis. These crystals grow as diamond-shaped wedges, with unit-cell parameters a = 50.92, b = 133.99, c = 70.88 A, alpha = beta = gamma = 90 degrees. The crystals belong to space group P2(1)2(1)2 and diffract to a minimum d spacing of 2.3 A on a MAR345 image plate with a Rigaku RU-200 rotating-anode X-ray generator. On the basis of density calculations, two monomers are predicted per asymmetric unit (Matthews coefficient, V(M) = 2.37 A(3) Da(-1)), with a solvent content of 48%.

  1. Co-crystallization as a separation technology: controlling product concentrations by co-crystals

    NARCIS (Netherlands)

    Urbanus, J.; Roelands, C.P.M.; Verdoes, D.; Jansens, P.J.; Horst, J.H. ter

    2010-01-01

    Co-crystallization is known as a product formulation technology, but it can also be used as a tool to solve crystallization problems. Product removal by co-crystallization in fermentations is used as a showcase to demonstrate the potential of co-crystallization as a separation technique. In

  2. Czochralski growth and topographic study of tetragonal (La,Sr)(Al,Ta)O 3 single crystals

    Science.gov (United States)

    Xiao, Jingzhong; Shao, Manjun; Tian, Yulian; Huang, Wanxia; Wang, Aihua; Yin, Shaotang

    2002-03-01

    Large tetragonal phase (La,Sr)(Al,Ta)O 3 (LSAT) crystals used as substrates for growing functional thin-film materials were successfully grown by the Czochralski method using [0 0 1] LaAlO 3 rod as seed. The crystal phase was determined by the method of powder X-ray diffraction analysis and the transmission spectrum indicates that the absorption edge of the crystal is at 270 nm while no apparent absorption peaks were found. Through the technique of environmental scanning electron microscopy and synchrotron radiation white-beam topography, the surface topography and defects were characterized, and clear and stable images of twins, micro-cracks, inclusions, grain boundaries, dislocation etch pits, and growth striations in the as-grown LSAT crystals were obtained.

  3. Rapid crystallization and morphological adjustment of zeolite ZSM-5 in nonionic emulsions

    Science.gov (United States)

    Zhang, Ying; Jin, Chao

    2011-01-01

    Zeolite ZSM-5 was synthesized for the first time in a nonionic emulsion composed of polyoxyethylated alkylphenol, butanol, cyclohexane and tetraethylammonium hydroxide (TEAOH)-containing zeolite synthesis mixture. The crystallization kinetics in the emulsion was investigated and the ZSM-5 product was characterized in detail by XRD, SEM, FT-IR, TG, N 2 adsorption and CHN analysis techniques. Compared with the conventionally hydrothermal synthesis with the same structure directing agent TEAOH, the emulsion system allows rapid crystallization of ZSM-5. The ZSM-5 product exhibits unusual agglomerated structure and possesses larger specific surface area. The FT-IR, TG results plus CHN analysis show the encapsulation of a trace of emulsion components in the emulsion ZSM-5. Control experiments show the emulsion system exerts the crystallization induction and morphological adjustment effects mainly during the aging period. The effects are tentatively attributed to the confined space domains, surfactant-water interaction as well as surfactant-growing crystals interaction existing in the emulsion.

  4. Melting ice, growing trade?

    Directory of Open Access Journals (Sweden)

    Sami Bensassi

    2016-05-01

    Full Text Available Abstract Large reductions in Arctic sea ice, most notably in summer, coupled with growing interest in Arctic shipping and resource exploitation have renewed interest in the economic potential of the Northern Sea Route (NSR. Two key constraints on the future viability of the NSR pertain to bathymetry and the future evolution of the sea ice cover. Climate model projections of future sea ice conditions throughout the rest of the century suggest that even under the most “aggressive” emission scenario, increases in international trade between Europe and Asia will be very low. The large inter-annual variability of weather and sea ice conditions in the route, the Russian toll imposed for transiting the NSR, together with high insurance costs and scarce loading/unloading opportunities, limit the use of the NSR. We show that even if these obstacles are removed, the duration of the opening of the NSR over the course of the century is not long enough to offer a consequent boost to international trade at the macroeconomic level.

  5. Can Solution Supersaturation Affect Protein Crystal Quality?

    Science.gov (United States)

    Gorti, Sridhar

    2013-01-01

    The formation of large protein crystals of "high quality" is considered a characteristic manifestation of microgravity. The physical processes that predict the formation of large, high quality protein crystals in the microgravity environment of space are considered rooted in the existence of a "depletion zone" in the vicinity of crystal. Namely, it is considered reasonable that crystal quality suffers in earth-grown crystals as a result of the incorporation of large aggregates, micro-crystals and/or large molecular weight "impurities", processes which are aided by density driven convective flow or mixing at the crystal-liquid interface. Sedimentation and density driven convection produce unfavorable solution conditions in the vicinity of the crystal surface, which promotes rapid crystal growth to the detriment of crystal size and quality. In this effort, we shall further present the hypothesis that the solution supersaturatoin at the crystal surface determines the growth mechanism, or mode, by which protein crystals grow. It is further hypothesized that protein crystal quality is affected by the mechanism or mode of crystal growth. Hence the formation of a depletion zone in microgravity environment is beneficial due to inhibition of impurity incorporatoin as well as preventing a kinetic roughening transition. It should be noted that for many proteins the magnitude of neither protein crystal growth rates nor solution supersaturation are predictors of a kinetic roughening transition. That is, the kinetic roughening transition supersaturation must be dtermined for each individual protein.

  6. BIOTECHNOLOGY IN FRUIT GROWING

    Directory of Open Access Journals (Sweden)

    Z. Jurković

    2008-09-01

    Full Text Available Research studies in the area of biotechnologies in fruit growing started at the Agricultural Institute Osijek in 2006 with the establishment of the first experimental in vitro laboratory for micropropagation. The laboratory started an active research related to the Project "Biotechnological methods in fruit tree identification, selection and propagation" Project is part of program "Preservation and revitalization of grape and fruit autochthonous cultivars". The goal of this research is to determine genetic differences between autochthonous and introduced cultivars of cherry as well as cultivars and types of sour cherry, to find and optimize a method for fast recovery of clonal material. A great number of cherry cultivars and types within the population of cv. Oblacinska sour cherry exists in Croatia. A survey with the purpose of selecting autochthonous cultivars for further selection has been done in previous research. Differences have been found in a number of important agronomic traits within the populations of cv. Oblačinska sour cherry. Autochthonous cherry cultivars are suspected to be synonyms of known old cultivars which were introduced randomly and have been naturalized under a local name. Identification and description of cultivars and types of fruits is based on special visible properties which were measurable or notable. In this approach difficulties arise from the effect of non-genetic factors on expression of certain traits. Genetic-physiological problem of S allele autoincompatibility exists within cherry cultivars. Therefore it is necessary to put different cultivars in the plantation to pollinate each other. Apart form the fast and certain sort identification independent of environmental factors, biotechnological methods based on PCR enable faster virus detection compared with classical serologic methods and indexing and cover a wider range of plant pathogens including those undetectable by other methods. Thermotherapy and

  7. Growing Galaxies Gently

    Science.gov (United States)

    2010-10-01

    New observations from ESO's Very Large Telescope have, for the first time, provided direct evidence that young galaxies can grow by sucking in the cool gas around them and using it as fuel for the formation of many new stars. In the first few billion years after the Big Bang the mass of a typical galaxy increased dramatically and understanding why this happened is one of the hottest problems in modern astrophysics. The results appear in the 14 October issue of the journal Nature. The first galaxies formed well before the Universe was one billion years old and were much smaller than the giant systems - including the Milky Way - that we see today. So somehow the average galaxy size has increased as the Universe has evolved. Galaxies often collide and then merge to form larger systems and this process is certainly an important growth mechanism. However, an additional, gentler way has been proposed. A European team of astronomers has used ESO's Very Large Telescope to test this very different idea - that young galaxies can also grow by sucking in cool streams of the hydrogen and helium gas that filled the early Universe and forming new stars from this primitive material. Just as a commercial company can expand either by merging with other companies, or by hiring more staff, young galaxies could perhaps also grow in two different ways - by merging with other galaxies or by accreting material. The team leader, Giovanni Cresci (Osservatorio Astrofisico di Arcetri) says: "The new results from the VLT are the first direct evidence that the accretion of pristine gas really happened and was enough to fuel vigorous star formation and the growth of massive galaxies in the young Universe." The discovery will have a major impact on our understanding of the evolution of the Universe from the Big Bang to the present day. Theories of galaxy formation and evolution may have to be re-written. The group began by selecting three very distant galaxies to see if they could find evidence

  8. Neutron inelastic scattering studies of crystal hydrates. Part of a coordinated programme on the application of research reactor neutron scattering techniques in the study of solids

    International Nuclear Information System (INIS)

    Amilius, Z.

    1977-12-01

    Using an inverted berillium filter spectrometer, neutrons inelastically scattered from the samples of hydrated and deuterated crystals of Cu Cl 2 .2H 2 O, Cu Cl 2 .2H 2 O and K 2 Cu Cl 2 .2D 2 O were measured, with the objective of determining the librational frequencies of the water molecule. The experiments were performed at room temperature only, permitting to draw only limited conclusions on the assignment of specific librational modes to the peak in the observed neutron spectra

  9. Preventing Crystal Agglomeration of Pharmaceutical Crystals Using Temperature Cycling and a Novel Membrane Crystallization Procedure for Seed Crystal Generation

    Directory of Open Access Journals (Sweden)

    Elena Simone

    2018-01-01

    Full Text Available In this work, a novel membrane crystallization system was used to crystallize micro-sized seeds of piroxicam monohydrate by reverse antisolvent addition. Membrane crystallization seeds were compared with seeds produced by conventional antisolvent addition and polymorphic transformation of a fine powdered sample of piroxicam form I in water. The membrane crystallization process allowed for a consistent production of pure monohydrate crystals with narrow size distribution and without significant agglomeration. The seeds were grown in 350 g of 20:80 w/w acetone-water mixture. Different seeding loads were tested and temperature cycling was applied in order to avoid agglomeration of the growing crystals during the process. Focused beam reflectance measurement (FBRM; and particle vision and measurement (PVM were used to monitor crystal growth; nucleation and agglomeration during the seeded experiments. Furthermore; Raman spectroscopy was used to monitor solute concentration and estimate the overall yield of the process. Membrane crystallization was proved to be the most convenient and consistent method to produce seeds of highly agglomerating compounds; which can be grown via cooling crystallization and temperature cycling.

  10. Enhancing the mechanical properties of single-crystal CVD diamond.

    Science.gov (United States)

    Liang, Qi; Yan, Chih-Shiue; Meng, Yufei; Lai, Joseph; Krasnicki, Szczesny; Mao, Ho-Kwang; Hemley, Russell J

    2009-09-09

    Approaches for enhancing the strength and toughness of single-crystal diamond produced by chemical vapor deposition (CVD) at high growth rates are described. CVD processes used to grow single-crystal diamond in high density plasmas were modified to incorporate boron and nitrogen. Semi-quantitative studies of mechanical properties were carried out using Vickers indentation techniques. The introduction of boron in single-crystal CVD diamond can significantly enhance the fracture toughness of this material without sacrificing its high hardness (∼78 GPa). Growth conditions were varied to investigate its effect on boron incorporation and optical properties by means of photoluminescence, infrared, and ultraviolet-visible absorption spectroscopy. Boron can be readily incorporated into single-crystal diamond by the methods used, but with nitrogen addition, the incorporation of boron was hindered. The spectroscopic measurements indicate that nitrogen and boron coexist in the diamond structure, which helps explain the origin of the enhanced fracture toughness of this material. Further, low pressure/high temperature annealing can enhance the intrinsic hardness of single-crystal CVD diamond by a factor of two without appreciable loss in fracture toughness. This doping and post-growth treatment of diamond may lead to new technological applications that require enhanced mechanical properties of diamond.

  11. Scattering of light by crystals

    CERN Document Server

    Hayes, William

    2012-01-01

    This authoritative graduate-level text describes inelastic light scattering by crystals and its use in the investigation of solid-state excitation, with experimental techniques common to all types of excitation. 1978 edition.

  12. Protein nutrition of growing cattle

    International Nuclear Information System (INIS)

    Chalupa, W.; Scott, G.C.

    1976-01-01

    In vitro studies on apparent degradation of amino acids by mixed and pure cultures of rumen bacteria demonstrated that (a) amino acids are degraded at differing rates (Arg, Thr>Lys, Phe, Leu, Ile>Val, Met); (b) certain amino acids (Met, Val, Try, Orn) are degraded to greater extents when fermented alone than in conjunction with other amino acids; (c) individual strains of rumen bacteria do not utilize all amino acids; and (d) total ruminal degradation of amino acids is the result of extensive bacterial interaction, and may vary greatly depending on the predominant types of micro-organisms present. Abomasal infusion of a mixture of 10 essential amino acids consistently increased nitrogen retention, but attempts to elucidate primary limiting amino acids were not conclusive. Our data suggested that supplementary methionine alone may not significantly increase nitrogen retention, but methionine must be present in order to obtain responses from other amino acids. Methionine plus lysine plus threonine usually increased nitrogen retention, but the magnitude of responses varied. The classical nitrogen balance technique may lack the sensitivity needed to detect small responses resulting from supplements of single amino acids, or growing cattle, unlike sheep used for wool growth, may not be suffering from specific amino acid deficiencies. Chemical suppression of ruminal degradation of amino acids produced significant increases in nitrogen retention and growth, and improved feed efficiencies. Productivity responses to rumen bypass techniques would seem to depend primarily upon (a) the degree to which dietary protein is degraded in the rumen, and (b) the quantity of absorbable amino acids supplied by the diet in relation to quantities required by the animal. (author)

  13. Growth of single crystals of BaFe12O19 by solid state crystal growth

    Science.gov (United States)

    Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

    2016-10-01

    Single crystals of BaFe12O19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe12O19 are buried in BaFe12O19+1 wt% BaCO3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe12O19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe12O19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth.

  14. Crystal Data

    Science.gov (United States)

    SRD 3 NIST Crystal Data (PC database for purchase)   NIST Crystal Data contains chemical, physical, and crystallographic information useful to characterize more than 237,671 inorganic and organic crystalline materials. The data include the standard cell parameters, cell volume, space group number and symbol, calculated density, chemical formula, chemical name, and classification by chemical type.

  15. A high compression crystal growth system

    International Nuclear Information System (INIS)

    Nieman, H.F.; Walton, A.A.; Powell, B.M.; Dolling, G.

    1980-01-01

    This report describes the construction and operating procedure for a high compression crystal growth system, capable of growing single crystals from the fluid phase over the temperature range of 4.2 K to 300 K, at pressures up to 900 MPa. Some experimental results obtained with the system are given for solid β-nitrogen. (auth)

  16. Crystallization phenomena in slags

    Science.gov (United States)

    Orrling, Carl Folke

    2000-09-01

    The crystallization of the mold slag affects both the heat transfer and the lubrication between the mold and the strand in continuous casting of steel. In order for mold slag design to become an engineering science rather than an empirical exercise, a fundamental understanding of the melting and solidification behavior of a slag must be developed. Thus it is necessary to be able to quantify the phenomena that occur under the thermal conditions that are found in the mold of a continuous caster. The double hot thermocouple technique (DHTT) and the Confocal Laser Scanning Microscope used in this study are two novel techniques for investigating melting and solidification phenomena of transparent slags. Results from these techniques are useful in defining the phenomena that occur when the slag film infiltrates between the mold and the shell of the casting. TTT diagrams were obtained for various slags and indicated that the onset of crystallization is a function of cooling rate and slag chemistry. Crystal morphology was found to be dependent upon the experimental temperature and four different morphologies were classified based upon the degree of melt undercooling. Continuous cooling experiments were carried out to develop CCT diagrams and it was found that the amount and appearance of the crystalline fraction greatly depends on the cooling conditions. The DHTT can also be used to mimic the cooling profile encountered by the slag in the mold of a continuous caster. In this differential cooling mode (DCT), it was found that the details of the cooling rate determine the actual response of the slag to a thermal gradient and small changes can lead to significantly different results. Crystal growth rates were measured and found to be in the range between 0.11 mum/s to 11.73 mum/s depending on temperature and slag chemistry. Alumina particles were found to be effective innoculants in oxide melts reducing the incubation time for the onset of crystallization and also extending

  17. Methodology of growing gigantic sapphire for GSLW project

    Science.gov (United States)

    Abgaryan, Artoush A.; Hartounian, Gomidas

    2005-09-01

    In our present world the Crystal Growth Technology does not have the necessary and sufficient conditions to manufacture large sizes; especially in the Sapphire Crystal world. We have a theoretical and methodological development for growing gigantic Sapphire Crystal Lenses. Our gigantic Sapphire Crystal Lenses have a unique optical characteristic which will be used in the Global System of Laser Weapons (GSLW); hence solving one of the crucial problems in the Relay Mirror System; where it captures the Laser beam from the earth surface, cleaning the beam in the Satellite and redirecting the laser energy to the precise desired target. Developed and solution for the temperature and heat-elasticity fields in growth systems are considered theoretical, in order to assess their effects on the optical symmetry of the growing crystal. The process is modeled using three-dimensional curvilinear coordinates to describe a closed, low-strain heat-elasticity system, with allowance made for the temperature variations of the thermal properties of the multilayer growth system, and nonlinear and unsteady-state process with arbitrary boundary conditions. The results presented as plots of the strain, stress, displacement, and temperature fields; demonstrate the potential of the method for designing new growth units and improving the existing ones and suggesting that crystals, in general, without frustration of optical symmetry can, in principle, be grown. In order to solve generalized problem for large optics. It is required to have super and correct mathematical computing calculations, and using basic fundamental laws of nature regarding optical symmetry in the crystal, and discovering the radical "new wave method" for crystal growth technology.

  18. Novel Transrotational Solid State Order Discovered by TEM in Crystallizing Amorphous Films

    Science.gov (United States)

    Kolosov, Vladimir

    Exotic thin crystals with unexpected transrotational microstructures have been discovered by transmission electron microscopy (TEM) for crystal growth in thin (10-100 nm) amorphous films of different chemical nature (oxides, chalcogenides, metals and alloys) prepared by various methods. Primarily we use our TEM bend contour technique. The unusual phenomenon can be traced in situ in TEM column: dislocation independent regular internal bending of crystal lattice planes in a growing crystal. Such transrotation (unit cell trans lation is complicated by small rotationrealized round an axis lying in the film plane) can result in strong regular lattice orientation gradients (up to 300 degrees per micrometer) of different geometries: cylindrical, ellipsoidal, toroidal, saddle, etc. Transrotation is increasing as the film gets thinner. Transrotational crystal resembles ideal single crystal enclosed in a curved space. Transrotational micro crystals have been eventually recognized by other authors in some vital thin film materials, i.e. PCMs for memory, silicides, SrTiO3. Atomic model and possible mechanisms of the phenomenon are discussed. New transrotational nanocrystalline model of amorphous state is also proposed Support of RF Ministry of Education and Science is acknowledged.

  19. Liquid Crystals in Decorative and Visual Arts

    Science.gov (United States)

    Makow, David

    The following sections are included: * INTRODUCTION * PIGMENT AND STRUCTURAL COLOURS AND THEIR RELEVANCE TO LIQUID CRYSTALS * LIQUID CRYSTAL MATERIALS AND TECHNIQUES FOR DECORATIVE AND VISUAL ARTS * Free cholesteric liquid crystals (FCLC's) * Encapsulated liquid crystals (ECLC's) * Nonsteroid Chiral nematics * Polymers with liquid crystalline properties (PLCs) * COLOUR PROPERTIES OF CHOLESTERIC LIQUID CRYSTALS (CLC's) * Molecular structure and the mechanism of colour production * Dependence of perceived colours on the angle of illumination and viewing * Dependence of perceived colours on temperature * Additive colour properties * Methods of doubling the peak reflectance of cholesteric liquid crystals * Colour gamut * Colours of superimposed and pigmented coatings * Colours in transmission * ACKNOWLEDGEMENTS * REFERENCES

  20. Precise Crystallization Age of the Bushveld Complex, South Africa: Direct Dating of the Platiniferous Merensky Reef Using the Zircon U-Pb Chemical Abrasion ID-TIMS Technique

    Science.gov (United States)

    Scoates, J. S.; Friedman, R. M.

    2006-12-01

    Determining the age of the Bushveld Complex, the world's largest layered intrusion and host to the majority of the known resources of platinum group elements, chromium and vanadium, has been difficult given the very low abundance of U-bearing minerals in the ultramafic-mafic cumulate rocks that comprise the body. This study provides a precise crystallization age for this giant layered intrusion and associated PGE mineralization, and allows for a re-evaluation of the duration and areal extent of Bushveld-related magmatic activity. Abundant, clear and colorless, anhedral zircon grains were separated from a sample of pegmatoidal feldspathic orthopyroxenite collected from the Merensky Reef in the West Mine (Townlands Shaft), Rustenburg Section. Low-U (21-105 ppm) zircon occurs with interstitial biotite and is locally directly in contact with sulfide. The zircon grains were subjected to different pre-treatment methods (no pre-treatment, air abrasion, and chemical abrasion [CA]) and isotope ratios for individual grains were analyzed by ID-TIMS. U-Pb data for the unabraded and air-abraded grains, and leachates from the CA procedure, are slightly discordant (0.1-1.6%) and yield overlapping 207Pb/206Pb dates ranging from 2052.5 to 2058.9 Ma. For the CA zircon grains (n=6), all data are concordant and give a Concordia age of 2054.3 ± 2.5 Ma (2sd, decay-constant errors included), which is interpreted as the age of crystallization of the Merensky Reef. This age is within error of published ages for the overlying, and locally cross-cutting, Bushveld or Lebowa granite suite, which implies that the entire Bushveld Complex was emplaced within a 2-3 myr interval. Comparison with ages from satellite intrusions (e.g. Moshaneng, Botswana; Uitkomst, South Africa) indicates that the Bushveld magmatic event at ca. 2054 Ma was regionally extensive across the northern Kaapvaal Craton and is consistent with relatively rapid emplacement of mantle-derived magmas along the Thabazimbi

  1. Lithium nanoparticles in lithium fluorite crystals

    Science.gov (United States)

    Ibragimova, E. M.; Mussaeva, M. A.; Kalanov, M. U.; Mukhamedshina, N. M.; Sandalov, V. N.

    2012-12-01

    Using intensive optical absorption techniques we studied formation of lithium nanoparticles in LiF crystals under 60Co-γ-irradiation in the dose range of 105-109 R at 300 K. At 106 R the F-center absorption band 4.95 eV grows up D>3 and splits into a symmetric doublet of narrow resonances similar to s1-metal nanoparticles surface plasmons. The maximal concentration 3.3·1017 cm-3 corresponds to ~14 nm distance between F-centers when they form F-F-pair and then M-center. Absorption band of divacancies 2.75 eV splits into triplet at > 107 R, when Lin nanoparticles 3.26 eV are formed. Twinned LiF lattice provides the defects ordering and assembling of Lin nanorods with the size of 8 nm related with the peak electric conductivity at 240-280 K.

  2. Liquid crystal tunable photonic crystal dye laser

    DEFF Research Database (Denmark)

    Buss, Thomas; Christiansen, Mads Brøkner; Smith, Cameron

    2010-01-01

    We present a dye-doped liquid crystal laser using a photonic crystal cavity. An applied electric field to the liquid crystal provides wavelength tunability. The photonic crystal enhances resonant interaction with the gain medium.......We present a dye-doped liquid crystal laser using a photonic crystal cavity. An applied electric field to the liquid crystal provides wavelength tunability. The photonic crystal enhances resonant interaction with the gain medium....

  3. Reporting with Visual Studio and Crystal Reports

    CERN Document Server

    Elkoush, Mahmoud

    2013-01-01

    A fast-paced, example-based guide to learn how to create a reporting application using Visual Studio and Crystal Reports.""Reporting with Visual Studio and Crystal Reports"" is for developers new to Crystal Reports. It will also prove useful to intermediate users who wish to explore some new techniques in Crystal Reports using Microsoft Visual Studio. Readers are expected to have basic knowledge of C#, Microsoft Visual Studio, and Structured Query Language (SQL).

  4. Growing container seedlings: Three considerations

    Science.gov (United States)

    Kas Dumroese; Thomas D. Landis

    2015-01-01

    The science of growing reforestation and conservation plants in containers has continually evolved, and three simple observations may greatly improve seedling quality. First, retaining stock in its original container for more than one growing season should be avoided. Second, strongly taprooted species now being grown as bareroot stock may be good candidates...

  5. Growth of strontium oxalate crystals in agar–agar gel

    Indian Academy of Sciences (India)

    Crystal growth; strontium oxalate; X-ray spectroscopy; FT–IR. 1. Introduction. The growth of single crystals of various substances has gained considerable attention of several investigators. Sophisticated and strenuous equipments have been devel- oped and employed for growing a wide variety of crystals; either may be due ...

  6. In situ investigation of dye adsorption on TiO2 films using a quartz crystal microbalance with a dissipation technique

    KAUST Repository

    Harms, Hauke A.

    2012-01-01

    Dye adsorption plays a crucial role in dye-sensitized solar cells. Herein, we demonstrate an in situ liquid-phase analytical technique to quantify in real time adsorption of dye and coadsorbates on flat and mesoporous TiO 2 films. For the first time, a molar ratio of co-adsorbed Y123 and chenodeoxycholic acid has been measured. © 2012 the Owner Societies.

  7. Solid state single crystal growth of three-dimensional faceted LaFeAsO crystals

    Science.gov (United States)

    Kappenberger, Rhea; Aswartham, Saicharan; Scaravaggi, Francesco; Blum, Christian G. F.; Sturza, Mihai I.; Wolter, Anja U. B.; Wurmehl, Sabine; Büchner, Bernd

    2018-02-01

    Solid state single crystal growth (SSCG) is a crystal growth technique where crystals are grown from a polycrystalline matrix. Here, we present single crystals of the iron pnictide LaFeAsO grown via SSCG using NaAs as a liquid phase to aid crystallization. The size of the as-grown crystals are up to 2 × 3 × 0.4 mm3. Typical for this method, but very uncommon for crystals of the pnictide superconductors and especially for the oxypnictides, the crystals show pronounced facets caused by considerable growth in c direction. The crystals were characterized regarding their composition, structure, magnetic, and thermodynamic properties. This sets the stage for further measurements for which single crystals are crucial such as any c axis and reciprocal space dependent measurements.

  8. Contributions to the crystal growth and characterization of the ferroelectric tetragonal tungsten bronze potassium-lithium niobate (K3Li2Nb5O15-KLN)

    International Nuclear Information System (INIS)

    Podlojenov, S.

    2003-01-01

    Undoped and Mg-doped KLN single crystals of optical quality were grown by the Czochralski technique. For decreasing temperature gradients in a growing single crystal an inductive afterheater was applied. The applicability for the frequency doubling of the KLN crystals was examined by using of powder SHG-tests. There was a clear correlation between the crystal composition (Nb-content) and the intensity of the second harmonic radiation. The niobium concentration of 49 mole % in the liquid phase can be appropriated as the boundary between the crystallization of paraelectric and ferroelectric KLN phase. All the grown KLTN crystals were paraelectric. The composition of the grown crystals was determined by X-ray fluorescence analysis and the atomic absorption analysis. The axial and radial concentration profiles of K and Nb over single crystals were determined by means of electron microprobe analysis. The segregation of elements is negligibly small in the investigated KLN single crystals. But in the KLTN single crystals the segregation of Ta was estimated to be in the order of 1 mole % / 1 cm crystal length. The ferroelectric phase transition in KLN was investigated with several techniques. The ferroelectric phase transition was estimated to lie within the range of 470-480 C. The second-order phase transition was detected by temperature-dependent measurements of the dielectric constant and the birefringence. But the DTA measurements indicated small thermal effect at the same temperature region, what refers to a first-order phase transition. The refractive indices of the paraelectric and the ferroelectric KLN phase were measured with an accuracy of 4 x 10 -5 over the wavelength region of 404-1083 nm. The data indicate that second harmonic generation in ferroelectric KLN crystals is possible at the primary wavelength 910 nm with non-critical phase matching (type I). (orig.)

  9. Growth and characterization of an organic single crystal: 2-[2-(4-Diethylamino-phenyl)-vinyl]-1-methyl-pyridinium iodide

    Science.gov (United States)

    Senthil, K.; Kalainathan, S.; Ruban Kumar, A.

    Optically transparent crystal of the organic salt DEASI (2-[2-(4-Diethylamino-phenyl)-vinyl]-1-methyl-pyridinium iodide) has been synthesized by using knoevenagel condensation reaction method. The synthesized material has been purified by successfully recrystallization process. Single crystals of DEASI have been grown by slow evaporation technique at room temperature. The solubility of the title material has been determined at different temperature in acetonitrile/methanol mixture. The cell parameters and crystallinity of the title crystal were determined by single crystal XRD. The powder diffraction was carried out to study the reflection plane of the grown crystal and diffraction peaks were indexed. The presence of different functional groups in the crystal was confirmed by Fourier transform infrared (FTIR) analysis. 1H NMR spectrum was recorded to confirm the presence of hydrogen nuclei in the synthesized material. The optical property of the title crystal was studied by UV-Vis-NIR spectroscopic analysis. The melting point and thermal property of DEASI were studied using TGA/DSC technique. The Vicker’s hardness (Hv) was carried out to know the category. The dielectric constant and dielectric loss of the compound decreases with an increase in frequencies. Chemical etching studies showed that the DEASI grows in the two dimensional growth mechanisms. The Kurtz-Perry powder second harmonic generation (SHG) test has done for title crystal.

  10. Growth and characterization of an organic single crystal: 2-[2-(4-diethylamino-phenyl)-vinyl]-1-methyl-pyridinium iodide.

    Science.gov (United States)

    Senthil, K; Kalainathan, S; Ruban Kumar, A

    2014-05-05

    Optically transparent crystal of the organic salt DEASI (2-[2-(4-Diethylamino-phenyl)-vinyl]-1-methyl-pyridinium iodide) has been synthesized by using knoevenagel condensation reaction method. The synthesized material has been purified by successfully recrystallization process. Single crystals of DEASI have been grown by slow evaporation technique at room temperature. The solubility of the title material has been determined at different temperature in acetonitrile/methanol mixture. The cell parameters and crystallinity of the title crystal were determined by single crystal XRD. The powder diffraction was carried out to study the reflection plane of the grown crystal and diffraction peaks were indexed. The presence of different functional groups in the crystal was confirmed by Fourier transform infrared (FTIR) analysis. (1)H NMR spectrum was recorded to confirm the presence of hydrogen nuclei in the synthesized material. The optical property of the title crystal was studied by UV-Vis-NIR spectroscopic analysis. The melting point and thermal property of DEASI were studied using TGA/DSC technique. The Vicker's hardness (Hv) was carried out to know the category. The dielectric constant and dielectric loss of the compound decreases with an increase in frequencies. Chemical etching studies showed that the DEASI grows in the two dimensional growth mechanisms. The Kurtz-Perry powder second harmonic generation (SHG) test has done for title crystal. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Crystal growth and structural analysis of zirconium sulphoselenide ...

    Indian Academy of Sciences (India)

    Wintec

    tion for the growth of these crystals is given. The stoichiometry of the grown crystals ... 646. Table 1. Growth parameters of zirconium sulphoselenide single crystal grown using chemical vapour transport technique. Physical .... The needle shaped, black or radish shining layered single crystals of zirconium sulphoselenide ...

  12. How Your Fetus Grows During Pregnancy

    Science.gov (United States)

    ... ACOG Pregnancy Book How Your Fetus Grows During Pregnancy Patient Education FAQs How Your Fetus Grows During Pregnancy Patient Education Pamphlets - Spanish How Your Fetus Grows During Pregnancy ...

  13. Formation of star-shaped calcite crystals with Mg 2+ inorganic mineralizer without organic template

    Science.gov (United States)

    Zhu, Liying; Zhao, Qingrui; Zheng, Xiuwen; Xie, Yi

    2006-04-01

    Star-shaped calcite crystals with 3¯m symmetry were obtained in the mixed solvent of ethanol and H 2O (4:1 vol%) using Mg 2+ as grow mineralizer without any organic template under the solvothermal condition. The crystals branched to the six directions perpendicular to the c-axis. In the process, Mg 2+ takes an important influence on such novel morphology via entering the crystal lattice of calcite to absorb the special plane and change the general growth habit. The aqueous solvent is favorable to form aragonite, while the presence of alcohol promotes the formation of calcite, the thermodynamically stable phase. The products were characterized by the techniques of XRD, SEM, SAED, IR and ICP. The formation process was also primarily studied.

  14. In situ inward epitaxial growth of bulk macroporous single crystals.

    Science.gov (United States)

    Chen, Chenlong; Sun, Shujing; Chou, Mitch M C; Xie, Kui

    2017-12-19

    The functionalities of porous materials could be significantly enhanced if the materials themselves were in single-crystal form, which, owing to structural coherence, would reduce electronic and optical scattering effects. However, growing macroporous single crystals remains a fundamental challenge, let alone manufacturing crystals large enough to be of practical use. Here we demonstrate a straightforward, inexpensive, versatile method for creating macroporous gallium nitride single crystals on a centimetre scale. The synthetic strategy is built upon a disruptive crystal growth mechanism that utilises direct nitridation of a parent LiGaO 2 single crystal rendering an inward epitaxial growth process. Strikingly, the resulting single crystals exhibit electron mobility comparable to that for bulk crystals grown by the conventional sodium flux method. This approach not only affords control of both crystal and pore size through synthetic modification, but proves generic, thus opening up the possibility of designing macroporous crystals in a wealth of other materials.

  15. Springer Handbook of Crystal Growth

    CERN Document Server

    Dhanaraj, Govindhan; Prasad, Vishwanath; Dudley, Michael

    2010-01-01

    Over the years, many successful attempts have been made to describe the art and science of crystal growth. Most modern advances in semiconductor and optical devices would not have been possible without the development of many elemental, binary, ternary, and other compound crystals of varying properties and large sizes. The objective of the Springer Handbook of Crystal Growth is to present state-of-the-art knowledge of both bulk and thin-film crystal growth. The goal is to make readers understand the basics of the commonly employed growth processes, materials produced, and defects generated. Almost 100 leading scientists, researchers, and engineers from 22 different countries from academia and industry have been selected to write chapters on the topics of their expertise. They have written 52 chapters on the fundamentals of bulk crystal growth from the melt, solution, and vapor, epitaxial growth, modeling of growth processes and defects, techniques of defect characterization as well as some contemporary specia...

  16. Growth of emerald single crystals

    International Nuclear Information System (INIS)

    Bukin, G.V.; Godovikov, A.A.; Klyakin, V.A.; Sobolev, V.S.

    1986-01-01

    In addition to its use for jewelry, emerald can also be used in low-noise microwave amplifiers. The authors discuss flux crystallization of emerald and note that when emerald is grown by this method, it is desirable to use solvents which dissolve emerald with minimum deviations from congruence but at the same time with sufficient high efficiency. Emerald synthesis and crystal growth from slowly cooled solutions is discussed as another possibility. The techniques are examined. Vapor synthesis and growht of beryl crystals re reviewed and the authors experimentally study the seeded CVD crystallization of beryl from BeO, Al 2 O 3 and SiO 2 oxides, by using complex compounds as carrier agents. The color of crystals of emerald and other varieties of beryl is detemined by slelective light absorption in teh visible part of the spectrum and depends on the density and structural positions of chromphore ions: chromium, iron, vanadium, nickel, manganese and cobalt

  17. A versatile Czochralski crystal growth system with automatic diameter control

    Science.gov (United States)

    Aggarwal, M. D.; Metzl, R.; Wang, W. S.; Choi, J.

    1995-07-01

    A versatile Czochralski crystal pulling system with automatic diameter control for the growth of nonlinear optical oxide crystals is discussed. Pure and doped bulk single crystals of bismuth silicon oxide (Bi12SiO20) have been successfully grown using this system. The system consists of a regular Czochralski type pulling system with provision for continuous weighing of the growing crystal to provide feedback for power control.

  18. Nucleation and crystal growth in batch crystallizers

    NARCIS (Netherlands)

    Janse, A.H.

    1977-01-01

    The aim of the present work is to gain knowledge of the mechanism of formation of the crystal size distribution in batch crystallizers in order to give directives for design and operation of batch crystallizers. The crystal size distribution is important for the separation of crystals and mother

  19. 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)

  20. Crystal study and econometric model

    Science.gov (United States)

    1975-01-01

    An econometric model was developed that can be used to predict demand and supply figures for crystals over a time horizon roughly concurrent with that of NASA's Space Shuttle Program - that is, 1975 through 1990. The model includes an equation to predict the impact on investment in the crystal-growing industry. Actually, two models are presented. The first is a theoretical model which follows rather strictly the standard theoretical economic concepts involved in supply and demand analysis, and a modified version of the model was developed which, though not quite as theoretically sound, was testable utilizing existing data sources.

  1. Investigation on the bulk growth of α-LiIO 3 single crystals and the ...

    Indian Academy of Sciences (India)

    2017-07-26

    Jul 26, 2017 ... Herein, we investigate to grow bulk size good quality crystals of α-LiIO3 based on the observed problems during its crystallization process. A systematic investigation was carried out to find the effect of pH on solubility, crystal growth, structural, surface and laser damage properties of α-LiIO3 single crystals.

  2. Photoelastic sphenoscopic analysis of crystals

    Science.gov (United States)

    Montalto, L.; Rinaldi, D.; Scalise, L.; Paone, N.; Davı, F.

    2016-01-01

    Birefringent crystals are at the basis of various devices used in many fields, from high energy physics to biomedical imaging for cancer detection. Since crystals are the main elements of those devices, a great attention is paid on their quality and properties. Here, we present a methodology for the photoelastic analysis of birefringent crystals, based on a modified polariscope. Polariscopes using conoscopic observation are used to evaluate crystals residual stresses in a precise but time consuming way; in our methodology, the light beam shape, which impinges on the crystal surface, has been changed from a solid cone (conoscopy) to a wedge (sphenoscopy). Since the polarized and coherent light is focused on a line rather than on a spot, this allows a faster analysis which leads to the observation, at a glance, of a spatial distribution of stress along a line. Three samples of lead tungstate crystals have been observed using this technique, and the obtained results are compared with the conoscopic observation. The samples have been tested both in unloaded condition and in a loaded configuration induced by means of a four points bending device, which allows to induce a known stress distribution in the crystal. The obtained results confirm, in a reliable manner, the sensitivity of the methodology to the crystal structure and stress.

  3. Photoelastic sphenoscopic analysis of crystals

    Energy Technology Data Exchange (ETDEWEB)

    Montalto, L. [DIISM, Dip. Di Ingegneria Industriale e Scienze Matematiche—Università Politecnica delle Marche, Ancona (Italy); SIMAU, Dip. Di Scienze e Ingegneria della Materia, dell’ambiente ed Urbanistica—Università Politecnica delle Marche, Ancona (Italy); Rinaldi, D. [SIMAU, Dip. Di Scienze e Ingegneria della Materia, dell’ambiente ed Urbanistica—Università Politecnica delle Marche, Ancona (Italy); Scalise, L.; Paone, N. [DIISM, Dip. Di Ingegneria Industriale e Scienze Matematiche—Università Politecnica delle Marche, Ancona (Italy); Davì, F. [DICEA, Dip. Di Ingegneria Civile, Edile e Architettura—Università Politecnica delle Marche, Ancona (Italy)

    2016-01-15

    Birefringent crystals are at the basis of various devices used in many fields, from high energy physics to biomedical imaging for cancer detection. Since crystals are the main elements of those devices, a great attention is paid on their quality and properties. Here, we present a methodology for the photoelastic analysis of birefringent crystals, based on a modified polariscope. Polariscopes using conoscopic observation are used to evaluate crystals residual stresses in a precise but time consuming way; in our methodology, the light beam shape, which impinges on the crystal surface, has been changed from a solid cone (conoscopy) to a wedge (sphenoscopy). Since the polarized and coherent light is focused on a line rather than on a spot, this allows a faster analysis which leads to the observation, at a glance, of a spatial distribution of stress along a line. Three samples of lead tungstate crystals have been observed using this technique, and the obtained results are compared with the conoscopic observation. The samples have been tested both in unloaded condition and in a loaded configuration induced by means of a four points bending device, which allows to induce a known stress distribution in the crystal. The obtained results confirm, in a reliable manner, the sensitivity of the methodology to the crystal structure and stress.

  4. Growing Oppression, Growing Resistance : LGBT Activism and Europeanisation in Macedonia

    NARCIS (Netherlands)

    Miškovska Kajevska, A.; Bilić, B.

    2016-01-01

    This chapter provides one of the first socio-historical overviews of the LGBT groups in Macedonia and argues that an important impetus for the proliferation of LGBT activities has been the growing state-endorsed homophobia starting from 2008. The homophobic rhetoric of the ruling parties was clearly

  5. Therapeutic Crystals

    Science.gov (United States)

    Bond, Charles S.

    2014-01-01

    Some readers might not fully know what the difference is between crystallography, and the "new age" practice of dangling crystals around the body to capitalise on their healing energy. The latter is often considered to be superstition, while ironically, the former has actually resulted in real rationally-based healing of human diseases…

  6. Ribbon Crystals

    DEFF Research Database (Denmark)

    Bohr, Jakob; Markvorsen, Steen

    2013-01-01

    A repetitive crystal-like pattern is spontaneously formed upon the twisting of straight ribbons. The pattern is akin to a tessellation with isosceles triangles, and it can easily be demonstrated with ribbons cut from an overhead transparency. We give a general description of developable ribbons...

  7. Nanoscopic Manipulation and Imaging of Liquid Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Rosenblatt, Charles S. [Case Western Reserve Univ., Cleveland, OH (United States)

    2014-02-04

    This is the final project report. The project’s goals centered on nanoscopic imaging and control of liquid crystals and surfaces. We developed and refined techniques to control liquid crystal orientation at surfaces with resolution as small as 25 nm, we developed an optical imaging technique that we call Optical Nanotomography that allows us to obtain images inside liquid crystal films with resolution of 60 x 60 x 1 nm, and we opened new thrust areas related to chirality and to liquid crystal/colloid composites.

  8. Crystal Growth of New Radiation Detector Materials in Microgravity, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — RMD proposes to conduct a series of crystal growth experiments on the International Space Station in the SUBSA furnace inside the MSG glovebox to grow crystals of...

  9. Solution-grown crystals for neutron radiation detectors, and methods of solution growth

    Science.gov (United States)

    Zaitseva, Natalia P; Hull, Giulia; Cherepy, Nerine J; Payne, Stephen A; Stoeffl, Wolfgang

    2012-06-26

    A method according to one embodiment includes growing an organic crystal from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source. A system according to one embodiment includes an organic crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source; and a photodetector for detecting the signal response of the organic crystal. A method according to another embodiment includes growing an organic crystal from solution, the organic crystal being large enough to exhibit a detectable signal response signature for neutrons from a radioactive source. An organic crystal according to another embodiment includes an organic crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source, wherein the organic crystal has a length of greater than about 1 mm in one dimension.

  10. Cheap heat grows in fields

    International Nuclear Information System (INIS)

    Haluza, I.

    2006-01-01

    Slovak farmers resemble the peasants from the film T he Magnificent Seven . They keep complaining about their fate but consider any innovation as an interference. And that is why they still have not started growing fast-growing wood although the number of heating plants processing bio-mass from forests and fields is growing. Natural gas is expensive and coal creates pollution. Energy from biomass is becoming a good business and also creates new business opportunities - growing the raw material it needs. Such heating plants usually use waste from wood processing companies and Slovak Forests (Lesy SR) has also started deliveries of chip wood from old forests. There are plantations of fast growing wood suitable for heat production of over 500-thousand hectares throughout the EU. This is about 10% of Slovakian's area where the first plantations are also already being set up. The first promising plantation project was launched this spring. And this is not a project launched and backed by a big company but a starting up businessman, Miroslav Forgac from Kosice. He founded his company, Forgim, last winter. Without big money involved and thank to a new business idea he managed to persuade farmers to set up the first plantations. He supplied the seedlings and the business has started with 75 ha of plantations around Trnava, Sala, Komarno, Lucenec, Poprad and Kosice. He is gradually signing contracts with other landowners and next year the area of plantations is set to grow by 1500 ha. Plantations of fast growing trees such as willow, poplar and acacia regenerate by new trees growing out of the roots of the old and from cut trees so from one seedling and one investment there can be several harvests. Swedish willows from Forgim regenerate 20 to 25 years after the first planting. And only then new seedlings have to be purchased. Using special machines that even cut the wood to wood chips the plantations can be 'harvested' every three years. Unlike crops, the fields do not

  11. Fourier Analysis and Structure Determination--Part III: X-ray Crystal Structure Analysis.

    Science.gov (United States)

    Chesick, John P.

    1989-01-01

    Discussed is single crystal X-ray crystal structure analysis. A common link between the NMR imaging and the traditional X-ray crystal structure analysis is reported. Claims that comparisons aid in the understanding of both techniques. (MVL)

  12. Growing Gallium Arsenide On Silicon

    Science.gov (United States)

    Radhakrishnan, Gouri

    1989-01-01

    Epitaxial layers of high quality formed on crystal plane. Present work reports successful growth of 1- and 2-micrometer thick layers of n-type, 7-ohms per cm, 2-inch diameter, Si substrate. Growth conducted in Riber-2300(R) MBE system. Both doped and undoped layers of GaAs grown. Chamber equipped with electron gun and camera for in-situ reflection high-energy-electron diffraction measurements. RHEED patterns of surface monitored continuously during slow growth stage.

  13. Epitaxial crystal growth by sputter deposition: Applications to semiconductors. Part 2

    International Nuclear Information System (INIS)

    Greene, J.E.

    1984-01-01

    The understanding of the physics of ion-surface interactions has progressed sufficiently to allow sputter depositinn to be used as a crystal growth technique for depositing a wide variety of single crystal elemental, compound, alloy, and superlattice semiconductors. In many cases, films with essentially bulk values of carrier concentrations and mobilities have been obtained. The controlled use of low energy particle bombardment of the growing film during sputter deposition has been shown to affect all stages of crystal growth ranging from adatom mobilities and nucleation kinetics to elemental incorporation probabilities. Such effects provide inherent advantages for sputter deposition over other vapor phase techniques for the low temperature growth of compound and alloy semiconductors and are essential in allowing the growth of new and unique single crystal metastable semiconductors. Part 1 of this review includes sections on experimental techniques, the physics of ion-surface interactions, and ion bombardment effects on film nucleation and growth, while Part 2 presents a discussion of recent results in the growth of elemental, III-V, II-VI, IV-VI, metastable, and other compound semiconductors

  14. Coaxial Electrospinning of Microfibres With Liquid Crystal in the Core

    OpenAIRE

    Lagerwall, Jan; McCann, J. T.; Formo, Eric; Scalia, Giusy; Xia, Younan

    2008-01-01

    Liquid crystal containing composite fibres were produced via coaxial electrospinning, demonstrating that this technique can be used for producing new functional fibres and/or to study the impact of extreme confinement on liquid crystal phases.

  15. Growing an Emerging Research University

    Science.gov (United States)

    Birx, Donald L.; Anderson-Fletcher, Elizabeth; Whitney, Elizabeth

    2013-01-01

    The emerging research college or university is one of the most formidable resources a region has to reinvent and grow its economy. This paper is the first of two that outlines a process of building research universities that enhance regional technology development and facilitate flexible networks of collaboration and resource sharing. Although the…

  16. Thallium toxicity: A growing concern

    OpenAIRE

    Saha A

    2005-01-01

    This review article deals with the growing concern of the toxicity of thallium. This article describes the characteristics of thallium, its potential sources of exposure, kinetics, and toxicity on human being and diagnosis of thallium poisoning. This article also describes some episodes of thallium poisoning arising from both occupational and nonoccupational exposure.

  17. Organization of growing random networks

    Energy Technology Data Exchange (ETDEWEB)

    Krapivsky, P. L.; Redner, S.

    2001-06-01

    The organizational development of growing random networks is investigated. These growing networks are built by adding nodes successively, and linking each to an earlier node of degree k with an attachment probability A{sub k}. When A{sub k} grows more slowly than linearly with k, the number of nodes with k links, N{sub k}(t), decays faster than a power law in k, while for A{sub k} growing faster than linearly in k, a single node emerges which connects to nearly all other nodes. When A{sub k} is asymptotically linear, N{sub k}(t){similar_to}tk{sup {minus}{nu}}, with {nu} dependent on details of the attachment probability, but in the range 2{lt}{nu}{lt}{infinity}. The combined age and degree distribution of nodes shows that old nodes typically have a large degree. There is also a significant correlation in the degrees of neighboring nodes, so that nodes of similar degree are more likely to be connected. The size distributions of the in and out components of the network with respect to a given node{emdash}namely, its {open_quotes}descendants{close_quotes} and {open_quotes}ancestors{close_quotes}{emdash}are also determined. The in component exhibits a robust s{sup {minus}2} power-law tail, where s is the component size. The out component has a typical size of order lnt, and it provides basic insights into the genealogy of the network.

  18. Heat stress in growing pigs

    NARCIS (Netherlands)

    Huynh Thi Thanh Thuy,

    2005-01-01

    Compared to other species of farm animals, pigs are more sensitive to high environmental temperatures, because they cannot sweat and do not pant so well. Furthermore, fast-growing lean pigs generate more heat than their congeners living in the wild. This, in combination with confined housing, makes

  19. Exploring Classroom Hydroponics. Growing Ideas.

    Science.gov (United States)

    National Gardening Association, Burlington, VT.

    Growing Ideas, the National Gardening Association's series for elementary, middle, and junior high school educators, helps teachers engage students in using plants and gardens as contexts for developing a deeper, richer understanding of the world around them. This volume's focus is on hydroponics. It presents basic hydroponics information along…

  20. Radionuclide techniques

    International Nuclear Information System (INIS)

    Alazraki, N.

    1988-01-01

    During approximately 25 years of experience with bone scanning, broad expansions in the clinical impact of radionuclide imaging on disorders of bones, joints, and soft tissues have occurred. This increased impact had its groundwork laid by advances in radiopharmaceuticals and instruments that are used for bone imaging. The progression from /sup 85/Sr- to /sup 99m/Tc-labeled phosphate and phosphonate compounds, coupled with the advance from crude rectilinear scanning techniques to whole body scintillation imaging with large crystal cameras and sophisticated electronics, has encourage use of radionuclide techniques in the evaluation of muscoloskeletal diseases. Many clinical studies have documented the high degree of sensitivity of the bone scan compared with that of the radiograph in detecting osseous and articular abnormalities

  1. Crystallization of MoO2 from gaseous phase

    International Nuclear Information System (INIS)

    Klinkova, L.A.; Skrebkova, E.D.

    1977-01-01

    The effect of the conditions of growing MoO 2 crystals from a gaseous phase in the presence of iodine on morphology and quality of the crystals has been studied. MoO 2 and Mo+MoO 3 have been used as an initial charge; iodine concentration has been changed from 0.5 to 10 mg/cm 3 . The quality of the crystals has been evaluated by the ratio between the resistance at room and helium temperatures. Optimum temperature of the crystallization zone on growing MoO 2 crystals is 850 deg since at that temperature the value of the residual resistance of the crystals is maximum. Iodine concentration must not exceed 0.5-2 mg/cm 3 . The obtained MoO 2 crystals possess good surface area; dislocation density does not exceed 10 -3 cm -2

  2. Biogenic Crystal and New Materials

    International Nuclear Information System (INIS)

    Bigi, A.; Falini, G.; Gazzano, M.; Roveri, N.; Ripamonti, A.; CNR, Bologna

    1998-01-01

    Organism use inorganic compounds to form inorganic-organic structured composites, with remarkable properties and functions. The target of many laboratory experiments is the natural processes simulation, in order to understand the molecular recognition process between the nucleation sites on the macromolecular matrix and the ions on the growing crystal nuclei. The understanding of biological phenomena opens new routes to the design of new materials or to the improvement of ceramics, polymers, semiconductors and composites [it

  3. Metadynamics studies of crystal nucleation

    Science.gov (United States)

    Giberti, Federico; Salvalaglio, Matteo; Parrinello, Michele

    2015-01-01

    Crystallization processes are characterized by activated events and long timescales. These characteristics prevent standard molecular dynamics techniques from being efficiently used for the direct investigation of processes such as nucleation. This short review provides an overview on the use of metadynamics, a state-of-the-art enhanced sampling technique, for the simulation of phase transitions involving the production of a crystalline solid. In particular the principles of metadynamics are outlined, several order parameters are described that have been or could be used in conjunction with metadynamics to sample nucleation events and then an overview is given of recent metadynamics results in the field of crystal nucleation. PMID:25866662

  4. Metadynamics studies of crystal nucleation

    Directory of Open Access Journals (Sweden)

    Federico Giberti

    2015-03-01

    Full Text Available Crystallization processes are characterized by activated events and long timescales. These characteristics prevent standard molecular dynamics techniques from being efficiently used for the direct investigation of processes such as nucleation. This short review provides an overview on the use of metadynamics, a state-of-the-art enhanced sampling technique, for the simulation of phase transitions involving the production of a crystalline solid. In particular the principles of metadynamics are outlined, several order parameters are described that have been or could be used in conjunction with metadynamics to sample nucleation events and then an overview is given of recent metadynamics results in the field of crystal nucleation.

  5. Hydrothermal Synthesis and Growth of Ti:Sapphire(Ti3+:Al2O3) Laser Crystals

    National Research Council Canada - National Science Library

    Bliss, David; Callahan, Michael; Wang, Buguo

    2007-01-01

    .... However, it is difficult to grow homogeneous crystals from the melt with uniform doping concentration because of the impurity segregation effect and more importantly, trivalent titanium instability...

  6. 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.

  7. Impact of Supramolecular Aggregation on the Crystallization Kinetics of Organic Compounds from the Supercooled Liquid State.

    Science.gov (United States)

    Kalra, Arjun; Tishmack, Patrick; Lubach, Joseph W; Munson, Eric J; Taylor, Lynne S; Byrn, Stephen R; Li, Tonglei

    2017-06-05

    Despite numerous challenges in their theoretical description and practical implementation, amorphous drugs are of growing importance to the pharmaceutical industry. One such challenge is to gain molecular level understanding of the propensity of a molecule to form and remain as a glassy solid. In this study, a series of structurally similar diarylamine compounds was examined to elucidate the role of supramolecular aggregation on crystallization kinetics from supercooled liquid state. The structural similarity of the compounds makes it easier to isolate the molecular features that affect crystallization kinetics and glass forming ability of these compounds. To examine the role of hydrogen-bonded aggregation and motifs on crystallization kinetics, a combination of thermal and spectroscopic techniques was employed. Using variable temperature FTIR, Raman, and solid-state NMR spectroscopies, the presence of hydrogen bonding in the melt and glassy state was examined and correlated with observed phase transition behaviors. Spectroscopic results revealed that the formation of hydrogen-bonded aggregates involving carboxylic acid and pyridine nitrogen (acid-pyridine aggregates) between neighboring molecules in the melt state impedes crystallization, while the presence of carboxylic acid dimers (acid-acid dimers) in the melt favors crystallization. This study suggests that glass formation of small molecules is influenced by the type of intermolecular interactions present in the melt state and the kinetics associated with the molecules to assemble into a crystalline lattice. For the compounds that form acid-pyridine aggregates, the formation of energy degenerate chains, produced due to conformational flexibility of the molecules, presents a kinetic barrier to crystallization. The poor crystallization tendency of these aggregates stems from the highly directional hydrogen-bonding interactions needed to form the acid-pyridine chains. Conversely, for the compounds that form acid

  8. Optimizing Crystal Volume for Neutron Diffraction Studies

    Science.gov (United States)

    Snell, E. H.

    2003-01-01

    For structural studies with neutron diffraction more intense neutron sources, improved sensitivity detector and larger volume crystals are all means by which the science is being advanced to enable studies on a wider range of samples. We have chosen a simplistic approach using a well understood crystallization method, with minimal amounts of sample and using design of experiment techniques to maximize the crystal volume all for minimum effort. Examples of the application are given.

  9. Studying Microstructure in Molecular Crystals With Nanoindentation

    DEFF Research Database (Denmark)

    Mishra, Manish Kumar; Desiraju, Gautam R; Ramamurty, Upadrasta

    2014-01-01

    Intergrowth polymorphism refers to the existence of distinct structural domains within a single crystal of a compound. The phenomenon is exhibited by form II of the active pharmaceutical ingredient felodipine, and the associated microstructure is a significant feature of the compound's structural...... identity. Employing the technique of nanoindentation on form II reveals a bimodal mechanical response on specific single-crystal faces, demonstrating distinct properties for two polymorphic forms within the same crystal....

  10. Heat stress in growing pigs

    OpenAIRE

    Huynh Thi Thanh Thuy

    2005-01-01

    Compared to other species of farm animals, pigs are more sensitive to high environmental temperatures, because they cannot sweat and do not pant so well. Furthermore, fast-growing lean pigs generate more heat than their congeners living in the wild. This, in combination with confined housing, makes it difficult for these pigs to regulate their heat balance. Heat stressed pigs have low performance, poor welfare, and, by pen fouling, they give higher emissions of odour and ammonia.Above certain...

  11. Carbonaceous Matter in Growing Nanoparticles

    Science.gov (United States)

    Johnston, M. V.; Stangl, C. M.; Horan, A. J.

    2015-12-01

    Atmospheric nanoparticles constitute the greatest portion of ambient aerosol loading by number. A major source of atmospheric nanoparticles is new particle formation (NPF), a gas to particle conversion process whereby clusters nucleate from gas phase precursors to form clusters on the order of one or a few nanometers and then grow rapidly to climatically relevant sizes. A substantial fraction of cloud condensation nuclei (CCN) are thought to arise from NPF. In order to better predict the frequency, growth rates, and climatic impacts of NPF, knowledge of the chemical mechanisms by which nucleated nanoparticles grow is needed. The two main contributors to particle growth are (neutralized) sulfate and carbonaceous matter. Particle growth by sulfuric acid condensation is generally well understood, though uncertainty remains about the extent of base neutralization and the relative roles of ammonia and amines. Much less is known about carbonaceous matter, and field measurements suggest that nitrogen-containing species are important. In this presentation, recent work by our group will be described that uses a combination of ambient measurements, laboratory experiments and computational work to study carbonaceous matter in growing nanoparticles. These studies span a range of particle sizes from the initial adsorption of molecules onto a nanometer-size ammonium bisulfate seed cluster to reactions in particles that are large enough to support condensed-phase chemistry.

  12. Phase-field crystal simulation facet and branch crystal growth

    Science.gov (United States)

    Chen, Zhi; Wang, Zhaoyang; Gu, Xinrui; Chen, Yufei; Hao, Limei; de Wit, Jos; Jin, Kexin

    2018-05-01

    Phase-field crystal model with one mode is introduced to describe morphological transition. The relationship between growth morphology and smooth density distribution was investigated. The results indicate that the pattern selection of dendrite growth is caused by the competition between interface energy anisotropy and interface kinetic anisotropy based on the 2D phase diagram. When the calculation time increases, the crystal grows to secondary dendrite at the dimensionless undercooling equal to - 0.4. Moreover, when noise is introduced in the growth progress, the symmetry is broken in the growth mode, and there becomes irregular fractal-like growth morphology. Furthermore, the single crystal shape develops into polycrystalline when the noise amplitude is large enough. When the dimensionless undercooling is less than - 0.3, the noise has a significant effect on the growth shape. In addition, the growth velocity of crystal near to liquid phase line is slow, while the shape far away from the liquid adapts to fast growth. Based on the simulation results, the method was proved to be effective, and it can easily obtain different crystal shapes by choosing the different points in 2D phase diagram.

  13. Peculiarities of linear thermal expansion of CuInS2 single crystal

    International Nuclear Information System (INIS)

    Akira, Nagaoka; Kenji, Yoshino; Hideto, Miyake

    2010-01-01

    Full text : I-III-VI 2 chalcopyrire semiconductors have made rapid progress in recent years. In addition chalcopyrite semiconductors show unique thermal properties. Usually, liner thermal expansion in semiconductors increases with increasing temperature. However, liner thermal expansion of most chalcopyrite semiconductors decreases at low temperature. For example, AgGaSe 2 shows decreasing the liner thermal expansion below 100 K 1 , 2). It is well known that high-quality single crystals of the I-III-VI 2 compounds are difficult to grow because most of the compounds grow through a peritectic reaction or a solid state transition during the cooling process. CuInS 2 single crystal can be grown by traveling heater method (THM), which is one of the solution growth techniques. Advantages of the THM growth are following that growth temperature is low compared with that of the other melt growth and larger crystals can be grown compared with a conventional solution growth. In a previous study, CuGaS 2 , CuGaSe 2 , CuGaTe 2 , CuInSe 2 ternary compounds have been obtained by the THM technique. In this work, it is investigated a liner thermal expansion of single crystal CuInS 2 by using X-ray diffraction. Measurement temperature was changed from 10 K to 300 K. From results of XRD measurement, it is calculated lattice constants of a and c axes and the liner thermal expansion. As a result, lattice constants of a axis increase with increasing temperature, that of c axis decreases with increasing temperature. The liner thermal expansion decreases for T 2 single crystal at low temperature

  14. Second harmonic chalcone crystal: Synthesis, growth and characterization

    Energy Technology Data Exchange (ETDEWEB)

    D' Silva, E.D., E-mail: deepak.dsilva@gmail.co [Department of studies in Physics, Mangalore University, Mangalagangotri, Mangalore 574199 (India); Narayan Rao, D. [School of Physics, University of Hyderabad, Hyderabad 500046 (India); Philip, Reji [Light and Matter Physics Group, Raman Research Institute, Bangalore 560080 (India); Butcher, Ray J. [Department of Chemistry, Howard University, Washington, DC 20059 (United States); Rajnikant [Department of Physics and Electronics, University of Jammu, Jammu Tawi 180006 (India); Dharmaprakash, S.M. [Department of studies in Physics, Mangalore University, Mangalagangotri, Mangalore 574199 (India)

    2011-05-15

    The novel nonlinear optical chalcone derivative (2E)-3-[4-(methylsulfanyl)phenyl]-1-(3-bromophenyl)prop-2-en-1-one (3Br4MSP) crystals have been grown by slow evaporation technique at ambient temperature. The crystal was subjected to different types of characterization method in order to study its possible application in nonlinear optics. The structure determination of the grown crystal was done by single crystal X-ray diffraction study. The morphology of the crystal is studied. The crystal was subjected to thermal analysis to find its thermal stability. The grown crystals were characterized for their optical transmission and mechanical hardness. The second harmonic generation (SHG) efficiency of the crystal is obtained by classical powdered technique. The laser damage threshold for 3Br4MSP crystal was determined using Q-switched Nd:YAG laser.

  15. Viscoelastic modes in chiral liquid crystals

    Indian Academy of Sciences (India)

    Viscoelastic properties of liquid crystals are very important for applications like display technology. However, there are not many direct techniques to study them. In this review, we describe our studies on the viscoelastic modes of some chiral liquid crystals using dynamic light scattering. We discuss viscoelastic modes ...

  16. Viscoelastic modes in chiral liquid crystals

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... Viscoelastic properties of liquid crystals are very important for applications like display technology. However, there are not many direct techniques to study them. In this review, we describe our studies on the viscoelastic modes of some chiral liquid crystals using dynamic light scattering. We discuss ...

  17. Crystal nucleation of colloidal hard dumbbells

    NARCIS (Netherlands)

    Ni, R.; Dijkstra, M.

    2011-01-01

    Using computer simulations, we investigate the homogeneous crystal nucleation in suspensions of colloidal hard dumbbells. The free energy barriers are determined by Monte Carlo simulations using the umbrella sampling technique. We calculate the nucleation rates for the plastic crystal and the

  18. Crystal growth and properties of novel organic nonlinear optical crystals of 4-Nitrophenol urea

    Energy Technology Data Exchange (ETDEWEB)

    Mohan, M. Krishna, E-mail: krishnamohan.m@ktr.srmuniv.ac.in; Ponnusamy, S.; Muthamizhchelvan, C.

    2017-07-01

    Single crystals of 4-Nitrophenol urea have been grown from water using slow evaporation technique at constant temperature, with the vision to improve the properties of the crystals. The unit cell parameters of the grown crystals were determined by single crystal and powder X-Ray diffraction. FTIR studies reveals the presence of different vibrational bands. The Optical studies confirmed that the crystal is transparent up to 360 nm .TGA and DSC studies were carried out to understand the thermal behavior of crystals. The SHG studies show the suitability of the crystals for NLO applications. The etching studies were carried out to study the behavior of the crystals under different conditions.These studies reveal that the crystals of 4-Nitrophenol urea are suitable for device applications. - Highlights: • 4-Nitrophenol urea crystals of dimensions 14 mm × 1 mm were grown. • UV–Visible studies indicate the crystal is transparent in the region of 370–800 nm. • Thermal studies show the crystal starts decomposing at 170 °C. • SHG studies indicate that the crystals have NLO efficiency 3.5 times that of KDP.

  19. Current trends in protein crystallization.

    Science.gov (United States)

    Gavira, José A

    2016-07-15

    Proteins belong to the most complex colloidal system in terms of their physicochemical properties, size and conformational-flexibility. This complexity contributes to their great sensitivity to any external change and dictate the uncertainty of crystallization. The need of 3D models to understand their functionality and interaction mechanisms with other neighbouring (macro)molecules has driven the tremendous effort put into the field of crystallography that has also permeated other fields trying to shed some light into reluctant-to-crystallize proteins. This review is aimed at revising protein crystallization from a regular-laboratory point of view. It is also devoted to highlight the latest developments and achievements to produce, identify and deliver high-quality protein crystals for XFEL, Micro-ED or neutron diffraction. The low likelihood of protein crystallization is rationalized by considering the intrinsic polypeptide nature (folded state, surface charge, etc) followed by a description of the standard crystallization methods (batch, vapour diffusion and counter-diffusion), including high throughput advances. Other methodologies aimed at determining protein features in solution (NMR, SAS, DLS) or to gather structural information from single particles such as Cryo-EM are also discussed. Finally, current approaches showing the convergence of different structural biology techniques and the cross-methodologies adaptation to tackle the most difficult problems, are presented. Current advances in biomacromolecules crystallization, from nano crystals for XFEL and Micro-ED to large crystals for neutron diffraction, are covered with special emphasis in methodologies applicable at laboratory scale. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Single Crystals Grown Under Unconstrained Conditions

    Science.gov (United States)

    Sunagawa, Ichiro

    Based on detailed investigations on morphology (evolution and variation in external forms), surface microtopography of crystal faces (spirals and etch figures), internal morphology (growth sectors, growth banding and associated impurity partitioning) and perfection (dislocations and other lattice defects) in single crystals, we can deduce how and by what mechanism the crystal grew and experienced fluctuation in growth parameters through its growth and post-growth history under unconstrained condition. The information is useful not only in finding appropriate way to growing highly perfect and homogeneous single crystals, but also in deciphering letters sent from the depth of the Earth and the Space. It is also useful in discriminating synthetic from natural gemstones. In this chapter, available methods to obtain molecular information are briefly summarized, and actual examples to demonstrate the importance of this type of investigations are selected from both natural minerals (diamond, quartz, hematite, corundum, beryl, phlogopite) and synthetic crystals (SiC, diamond, corundum, beryl).

  1. Crystal shapes on striped surface domains

    International Nuclear Information System (INIS)

    Valencia, Antoni

    2004-01-01

    The equilibrium shapes of a simple cubic crystal in contact with a planar chemically patterned substrate are studied theoretically using an effective interface model. The substrate is primarily made of lyophobic material and is patterned with a lyophilic (easily wettable) stripe domain. Three regimes can be distinguished for the equilibrium shapes of the crystal. The transitions between these regimes as the volume of the crystal is changed are continuous or discontinuous depending on the strength of the couplings between the crystal and the lyophilic and lyophobic surface domains. If the crystal grows through a series of states close to equilibrium, the discontinuous transitions correspond to growth instabilities. These transitions are compared with similar results that have been obtained for a volume of liquid wetting a lyophilic stripe domain

  2. DNA Brick Crystals with Prescribed Depth

    Science.gov (United States)

    Ke, Yonggang; Ong, Luvena L.; Sun, Wei; Song, Jie; Dong, Mingdong; Shih, William M.; Yin, Peng

    2014-01-01

    We describe a general framework for constructing two-dimensional crystals with prescribed depth and sophisticated three-dimensional features. These crystals may serve as scaffolds for the precise spatial arrangements of functional materials for diverse applications. The crystals are self-assembled from single-stranded DNA components called DNA bricks. We demonstrate the experimental construction of DNA brick crystals that can grow to micron-size in the lateral dimensions with precisely controlled depth up to 80 nanometers. They can be designed to display user-specified sophisticated three-dimensional nanoscale features, such as continuous or discontinuous cavities and channels, and to pack DNA helices at parallel and perpendicular angles relative to the plane of the crystals. PMID:25343605

  3. The Effect of Protein Impurities on Lysozyme Crystal Growth

    Science.gov (United States)

    Judge, Russell A.; Forsythe, Elizabeth L.; Pusey, Marc L.

    1998-01-01

    While bulk crystallization from impure solutions is used industrially as a purification step for a wide variety of materials, it is a technique that has rarely been used for proteins. Proteins have a reputation for being difficult to crystallize and high purity of the initial crystallization solution is considered paramount for success in the crystallization. Although little is written on the purifying capability of protein crystallization or of the effect of impurities on the various aspects of the crystallization process, recent published reports show that crystallization shows promise and feasibility as a purification technique for proteins. In order to further examine the issue of purity in macromolecule crystallization this study investigates the effect of the protein impurities, avidin, ovalbumin and conalbumin, at concentrations up to 50%, on the solubility, crystal face growth rates and crystal purity, of the protein lysozyme. Solubility was measured in batch experiments while a computer controlled video microscope system was used to measure the f {101} and {101} lysozyme crystal face growth rates. While little effect was observed on solubility and high crystal purity was obtained (>99.99%), the effect of the impurities on the face growth rates varied from no effect to a significant face specific effect leading to growth cessation, a phenomenon that is frequently observed in protein crystal growth. The results shed interesting light on the effect of protein impurities on protein crystal growth and strengthen the feasibility of using crystallization as a unit operation for protein purification.

  4. Growing Hemorrhagic Choroidal Fissure Cyst.

    Science.gov (United States)

    Karatas, Ayse; Gelal, Fazıl; Gurkan, Gokhan; Feran, Hamit

    2016-03-01

    Choroidal fissure cysts are often incidentally discovered. They are usually asymptomatic. The authors report a case of growing and hemorrhagic choroidal fissure cyst which was treated surgically. A 22-year-old female presented with headache. Cranial MRI showed a left-sided choroidal fissure cyst. Follow-up MRI showed that the size of the cyst had increased gradually. Twenty months later, the patient was admitted to our emergency department with severe headache. MRI and CT showed an intracystic hematoma. Although such cysts usually have a benign course without symptoms and progression, they may rarely present with intracystic hemorrhage, enlargement of the cyst and increasing symptomatology.

  5. Growing energy demand - environmental impact

    International Nuclear Information System (INIS)

    Rama Rao, G.A.

    2012-01-01

    Scientists can bring information, insights, and analytical skills to bear on matters of public concern. Often they can help the public and its representatives to understand the likely causes of events (such as natural and technological disasters) and to estimate the possible effects of projected policies. Often they can testify to what is not possible. Even so, scientists can seldom bring definitive answers to matters of public debate. Some issues are too complex to fit within the current scope of science, or there may be little reliable information available, or the values involved may lie outside of science. Scientists and technologists strive to find an answer to the growing energy demand

  6. Lysine requirements of growing emus.

    Science.gov (United States)

    Mannion, P F; Kent, P B; Barram, K M; Trappett, P C; Blight, G W; Sales, J

    1999-05-01

    1. The lysine requirement of growing emus between 23 and 65 d of age was determined according to growth response variables. 2. The optimal lysine requirement of emus was found to be 0.83 and 0.90 g/MJ ME for growth rate and gain:food ratio respectively. These findings are in accordance with the recommended value of 0.80 g/MJ ME, but is lower than the recommended value for ostriches (1.02 g/MJ ME) and higher than determined values for broilers (0.75 g/MJ ME) of the same age range.

  7. Thermotropic liquid crystals recent advances

    CERN Document Server

    Ramamoorthy, Ayyalusamy

    2007-01-01

    This book covers developments in the field of thermotropic liquid crystals and their functional importance. It also presents advances related to different sub-areas pertinent to this interdisciplinary area of research. This text brings together research from synthetic scientists and spectroscopists and attempts to bridge the gaps between these areas. New physical techniques that are powerful in characterizing these materials are discussed.

  8. 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.

  9. Acoustic Methods to Monitor Protein Crystallization and to Detect Protein Crystals in Suspensions of Agarose and Lipidic Cubic Phase

    Energy Technology Data Exchange (ETDEWEB)

    Ericson, Daniel L.; Yin, Xingyu; Scalia, Alexander; Samara, Yasmin N.; Stearns, Richard; Vlahos, Harry; Ellson, Richard; Sweet, Robert M.; Soares, Alexei S.

    2016-02-01

    Improvements needed for automated crystallography include crystal detection and crystal harvesting. A technique that uses acoustic droplet ejection to harvest crystals was previously reported. Here a method is described for using the same acoustic instrument to detect protein crystals and to monitor crystal growth. Acoustic pulses were used to monitor the progress of crystallization trials and to detect the presence and location of protein crystals. Crystals were detected, and crystallization was monitored in aqueous solutions and in lipidic cubic phase. Using a commercially available acoustic instrument, crystals measuring ~150 µm or larger were readily detected. Simple laboratory techniques were used to increase the sensitivity to 50 µm by suspending the crystals away from the plastic surface of the crystallization plate. This increased the sensitivity by separating the strong signal generated by the plate bottom that can mask the signal from small protein crystals. It is possible to further boost the acoustic reflection from small crystals by reducing the wavelength of the incident sound pulse, but our current instrumentation does not allow this option. In the future, commercially available sound-emitting transducers with a characteristic frequency near 300 MHz should detect and monitor the growth of individual 3 µm crystals.

  10. Acoustic Methods to Monitor Protein Crystallization and to Detect Protein Crystals in Suspensions of Agarose and Lipidic Cubic Phase.

    Science.gov (United States)

    Ericson, Daniel L; Yin, Xingyu; Scalia, Alexander; Samara, Yasmin N; Stearns, Richard; Vlahos, Harry; Ellson, Richard; Sweet, Robert M; Soares, Alexei S

    2016-02-01

    Improvements needed for automated crystallography include crystal detection and crystal harvesting. A technique that uses acoustic droplet ejection to harvest crystals was previously reported. Here a method is described for using the same acoustic instrument to detect protein crystals and to monitor crystal growth. Acoustic pulses were used to monitor the progress of crystallization trials and to detect the presence and location of protein crystals. Crystals were detected, and crystallization was monitored in aqueous solutions and in lipidic cubic phase. Using a commercially available acoustic instrument, crystals measuring ~150 µm or larger were readily detected. Simple laboratory techniques were used to increase the sensitivity to 50 µm by suspending the crystals away from the plastic surface of the crystallization plate. This increased the sensitivity by separating the strong signal generated by the plate bottom that can mask the signal from small protein crystals. It is possible to further boost the acoustic reflection from small crystals by reducing the wavelength of the incident sound pulse, but our current instrumentation does not allow this option. In the future, commercially available sound-emitting transducers with a characteristic frequency near 300 MHz should detect and monitor the growth of individual 3 µm crystals. © 2015 Society for Laboratory Automation and Screening.

  11. Characterising laser beams with liquid crystal displays

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2016-09-01

    Full Text Available the intensity, phase, wavefront, Poynting vector, and orbital angular momentum density of unknown optical fields. This measurement technique makes use of a single spatial light modulator (liquid crystal display), a Fourier transforming lens and detector (CCD...

  12. Rapid leak detection with liquid crystals

    Science.gov (United States)

    Heisman, R. M.; Iceland, W. F.; Ruppe, E. P.

    1978-01-01

    Small leaks in vacuum lines are detected by applying liquid-crystal coating, warming suspected area, and observing color change due to differential cooling by leak jet. Technique is used on inside or outside walls of vacuum-jacketed lines.

  13. Mechanical Properties Of Single Crystal Ceramics

    Science.gov (United States)

    Rowcliffe, D. J.; Johnson, S. M.

    1987-03-01

    Approaches to characterizing the mechanical behavior of single crystal ceramics are reviewed. Consideration is given to techniques applicable to large crystals and to indentation techniques that can be used on crystals of 1 mm or less. The importance of flaws in controlling the mechanical behavior of brittle ceramics is discussed, leading to an emphasis on fracture mechanics methods. These techniques are applicable to the determination of fracture toughness and to the measurement of slow crack growth in aggresive environments. Indentation processes have been analyzed extensively and the good understanding of stress fields and micro-mechanics of indentation has led to techniques to measure hardness, toughness and elastic modulus. Measurements of hardness anistropy can be used to determine slip planes and also provide considerable information on local plastic flow in brittle crystals.

  14. How fast do eels grow

    International Nuclear Information System (INIS)

    Hansen, H.J.M.

    1988-01-01

    Not so very much about the growth pattern of the eel is known yet. Eels move about nearly all the time. They are thus very difficult to follow and we do not, for examble, yet know how long it actually takes for them to grow to maturity in the wild. So far, a macroscopic analysis of the number of bright and dark areas (growth rings) in the 'earstones' has been used to determine eel age, but this method was recently challenged. Use of radioisotopes has been suggested previously for this purpose. For this present study the rare earth elements, europium-152 and europium-155 are used. When incubated in artificial sea water, a satisfactory final radioactive label was achieved. Two experiments were planned in collaboration with the Swedish Environmental Protection Agency. 2000 Elvers were set out in 1982, in the cooling water outlet of the Oskarshamn nuclear power plant, each marked with europium-155. In 1984 another 10 000 elvers labelled with europium-152 were set out under similar conditions. The idea was mainly to see how fast the eels would grow, and to compare their known age with that determined by examining the earstones. Results showed that there was no clear-cut correlation between actual eel age and the biological age determination used so far. During four years, only 10 of the original 1300 eels were recaptured. It is thus hard to say anything definite from our results on the viability of setting out elvers in the environment

  15. Development of novel growth methods for halide single crystals

    Science.gov (United States)

    Yokota, Yuui; Kurosawa, Shunsuke; Shoji, Yasuhiro; Ohashi, Yuji; Kamada, Kei; Yoshikawa, Akira

    2017-03-01

    We developed novel growth methods for halide scintillator single crystals with hygroscopic nature, Halide micro-pulling-down [H-μ-PD] method and Halide Vertical Bridgman [H-VB] method. The H-μ-PD method with a removable chamber system can grow a single crystal of halide scintillator material with hygroscopicity at faster growth rate than the conventional methods. On the other hand, the H-VB method can grow a large bulk single crystal of halide scintillator without a quartz ampule. CeCl3, LaBr3, Ce:LaBr3 and Eu:SrI2 fiber single crystals could be grown by the H-μ-PD method and Eu:SrI2 bulk single crystals of 1 and 1.5 inch in diameter could be grown by the H-VB method. The grown fiber and bulk single crystals showed comparable scintillation properties to the previous reports using the conventional methods.

  16. Research on crystal growth by using pressure as a control parameter; Atsuryoku seigyo ni yoru kessho seicho ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-10-31

    This research project aims to establish a technique for crystal growth using pressure as a principal control parameter, and combining it with a microgravity condition, to develop a novel process material fabrication. Since the solubility of materials depends on pressure, it is possible to control a supersaturated condition for crystal growth by changing pressure. The growth condition can be controlled precisely, which is not possible by conventional methods that vary temperature and other factors. On the other hand, because a concentration diffusing field is formed autonomically around crystals in association with their growth, density convection is generated under gravity as a result of difference in the concentrations, making the growth conditions severely complex and uncontrollable. Ideal crystal growth condition control may be possible if the pressure control is performed under micro-gravity by which generation of the density convection can be suppressed. Realization has been achieved on in-situ observation by using high-magnification microscope which uses a diamond anvil cell, development of a hydraulic type optic pressure cell, and a high- speed crystal growing technology by means of pressure control utilizing the cell. New findings were also obtained on effects of pressure on crystal forms, and the pressure induced solid phase transfer mechanism. 67 refs., 49 figs., 3 tabs.

  17. Scientific/Technical Report: Improvement in compensation and crystal growth of cadmium zinc telluride radiation detectors

    International Nuclear Information System (INIS)

    Kelvin G. Lynn; Kelly A. Jones

    2007-01-01

    Comparison of actual accomplishments with goals and objectives: (1) Growth of 12 ingots--Washington State University (WSU) more than met this goal for the project by growing 12 final ingots for the year. Nine of the twelve crystal growth ingots resolved gamma radiation at room temperature. The other three ingots where resistivity of ∼ 3 x 10 8 Ohm*cm for CG32a, CG36, and CG42 lower than expected, however none of these were tried with blocking contacts. All ingots were evaluated from tip to heel. In these three cases, the group III, dopant Aluminum (Al) was not detected to a level to compensate the Cd vacancies in the cadmium zinc telluride (CZT) thus the ingots were lower resistivity. The nine ingots that were successful radiation detectors averaged a bulk resistivity of 1.25 x 10 10 Ohm*cm and with a average μτ product for electrons of ∼ 2 x 10 -4 cm 2 /V with a 1/4 microsecond shaping time with samples ∼2 mm in thickness. (2) Attempt new compensations techniques--WSU also met this goal. Several doping schemes were attempted and investigated with various amounts of excess Tellurium added to the growth. The combination of Al and Erbium (Er) were first attempted for these ingots and subsequently CG34 was grown with Al, Er and Holmium. These compensation techniques produced radiation detectors and are currently under investigation. These growths were made with significant different doping levels to determine the affect of the dopants. CG43 was doped with Indium and Er. Indium was introduced instead of Al to determine if Indium is more soluble than Al for CZT and was less oxidized. This may decrease the amount of low resistivity ingots grown by doping with Indium instead of Al. (3) Grow large single crystals--Several changes in approach occurred in the crystal growth furnace. Steps were taken to maximize the crystal growth interface during growth by modifying liners, quartz, heat sinks, crucibles and various growth steps and temperature profiles. CG39 ingot

  18. Crystal growth, electrical and photophysical properties of Tl2S ...

    Indian Academy of Sciences (India)

    The Tl2S compound was prepared in a single crystal form using a special local technique, and the obtained crystals were analysed by X-ray diffraction. For the resultant crystals, the electrical properties (electrical conductivity and Hall effect) and steady-state photoconductivity were elucidated in this work. The electrical ...

  19. Growth of strontium oxalate crystals in agar–agar gel

    Indian Academy of Sciences (India)

    single diffusion technique in which the gel medium does. Figure 4. a. Transparent prismatic bi-pyramidal platy shaped crystals at interstitial and spherulite crystals well inside test-tube using NH4Cl additive in single diffusion and b. some good quality crystals obtained using NH4Cl as addictive in single diffusion.

  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. Liquid Crystal Devices.

    Science.gov (United States)

    Bradshaw, Madeline J.

    1983-01-01

    The nature of liquid crystals and several important liquid crystal devices are described. Ideas for practical experiments to illustrate the properties of liquid crystals and their operation in devices are also described. (Author/JN)

  2. Liquid Crystal Inquiries.

    Science.gov (United States)

    Marroum, Renata-Maria

    1996-01-01

    Discusses the properties and classification of liquid crystals. Presents a simple experiment that illustrates the structure of liquid crystals and the differences between the various phases liquid crystals can assume. (JRH)

  3. Supplies should match growing demand

    International Nuclear Information System (INIS)

    Rasmusen, H.J.

    1997-01-01

    The natural gas industry is currently enjoying healthy growth prospects. Not only is the demand for natural gas steadily growing; the outlook for increasing gas reserves is promising as well. The success of natural gas in the marketplace reflects, on one hand, continuous attention paid to public and customer requirements and, on the other hand, the ability of the gas industry to direct technological developments toward the increasing public demand for gas at competitive market prices supplied in a reliable, safe and environmentally friendly manner. In the past, the gas industry has been involved in the development of technologies for everything from gas production to the end user and from borehole to burner tip, and the author believes that the industry must continue or even increase its emphasis on technology in the future in order to capture new market opportunities. He explains this by looking at the supply side, the demand side and the structural side of the business

  4. Growing the Blockchain information infrastructure

    DEFF Research Database (Denmark)

    Jabbar, Karim; Bjørn, Pernille

    2017-01-01

    In this paper, we present ethnographic data that unpacks the everyday work of some of the many infrastructuring agents who contribute to creating, sustaining and growing the Blockchain information infrastructure. We argue that this infrastructuring work takes the form of entrepreneurial actions......, which are self-initiated and primarily directed at sustaining or increasing the initiator’s stake in the emerging information infrastructure. These entrepreneurial actions wrestle against the affordances of the installed base of the Blockchain infrastructure, and take the shape of engaging...... or circumventing activities. These activities purposefully aim at either influencing or working around the enablers and constraints afforded by the Blockchain information infrastructure, as its installed base is gaining inertia. This study contributes to our understanding of the purpose of infrastructuring, seen...

  5. Growing bubbles rising in line

    Directory of Open Access Journals (Sweden)

    John F. Harper

    2001-01-01

    Full Text Available Over many years the author and others have given theories for bubbles rising in line in a liquid. Theory has usually suggested that the bubbles will tend towards a stable distance apart, but experiments have often showed them pairing off and sometimes coalescing. However, existing theory seems not to deal adequately with the case of bubbles growing as they rise, which they do if the liquid is boiling, or is a supersaturated solution of a gas, or simply because the pressure decreases with height. That omission is now addressed, for spherical bubbles rising at high Reynolds numbers. As the flow is then nearly irrotational, Lagrange's equations can be used with Rayleigh's dissipation function. The theory also works for bubbles shrinking as they rise because they dissolve.

  6. Investigation on the crystal growth, molecular structure and nonlinear optical susceptibilities of 2-[2-(4-Ethoxy-phenyl)-vinyl]-1-ethyl-stilbazolium iodide (EESI) by Z-scan technique using He-Ne laser for third-order nonlinear optical applications

    Science.gov (United States)

    Senthil, K.; Kalainathan, S.; Kondo, Y.; Hamada, F.; Yamada, M.

    2017-05-01

    Organic 2-[2-(4-Ethoxy-phenyl)-vinyl]-1-ethyl-stilbazolium iodide (EESI), a derivative of the stilbazolium family single crystal was synthesized by condensation method. Nearly perfect as-gown single crystals of EESI structure was confirmed by single-crystal X-ray diffraction studies. The crystal has a triclinic system with the space group P-1, the molecule consists of one pyridinium cation, one iodide anion, and 0·5H2O molecules. The nature of charge transfer, molecular properties, electrostatic potential map, and HOMO-LUMO energy gap of EESI have been theoretically investigated by Sparton'10 V1.0.1 program. The optical transparency of EESI was studied by Uv-Visible spectral analysis. The growth features were observed during the etching studies using a Carl Zeiss optical microscope (50X magnification). The mechanical behavior of the crystal was estimated by Vickers microhardness test, which shows reverse indentation size effect (RISE) with good mechanical stability. Both the dielectric constant and dielectric loss increases with the increasing temperature and attain almost constant at higher frequencies, which justify the crystal quality and essential parameter for electro-optic device applications. The complex impedance analysis explains the electrical property of EESI. TGA and DTA measurements determined the thermal stability of the grown crystal. Laser-induced damage threshold energy measurements exhibit that the excellent resistance with good threshold energy up to 2.08 GW/cm2 that was found to be more than that of some known organic and inorganic NLO crystals. Photoconductivity of EESI crystal confirms that the positive photoconductivity nature. Also, the third-order nonlinear optical (NLO) properties of EESI were investigated by using the single beam Z-scan technique under the Visible light (632.8 nm) region. The results show that EESI has effective third-order nonlinear optical property with the nonlinear refractive index n2 =1.787×10-11m2/W, third

  7. A Cannibalistic Approach to Grand Canonical Crystal Growth.

    Science.gov (United States)

    Karmakar, Tarak; Piaggi, Pablo M; Perego, Claudio; Parrinello, Michele

    2018-04-04

    Canonical molecular dynamics simulations of crystal growth from solution suffer from severe finite-size effects. As the crystal grows, the solute molecules are drawn from the solution to the crystal, leading to a continuous drop in the solution concentration. This is in contrast to experiments in which the crystal grows at an approximately constant supersaturation of a bulk solution. Recently, Perego et al. [ J. Chem. Phys. 2015, 142, 144113] showed that in a periodic setup in which the crystal is represented as a slab, the concentration in the vicinity of the two surfaces can be kept constant while the molecules are drawn from a part of the solution that acts as a molecular reservoir. This method is quite effective in studying crystallization under controlled supersaturation conditions. However, once the reservoir is depleted, the constant supersaturation conditions cannot be maintained. We propose a variant of this method to tackle this depletion problem by simultaneously dissolving one side of the crystal while letting the other side grow. A continuous supply of particles to the solution due to the crystal dissolution maintains a steady solution concentration and avoids reservoir depletion. In this way, a constant supersaturation condition can be maintained for as long as necessary. We have applied this method to study the growth and dissolution of urea crystal from water solution under constant supersaturation and undersaturation conditions, respectively. The computed growth and dissolution rates are in good agreement with those obtained in previous studies.

  8. Meniscus Imaging for Crystal-Growth Control

    Science.gov (United States)

    Sachs, E. M.

    1983-01-01

    Silicon crystal growth monitored by new video system reduces operator stress and improves conditions for observation and control of growing process. System optics produce greater magnification vertically than horizontally, so entire meniscus and melt is viewed with high resolution in both width and height dimensions.

  9. 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

  10. The growing importance of cold storage; Koudeopslag wordt standaard

    Energy Technology Data Exchange (ETDEWEB)

    Philippens, M. [Videm Communicatie, Utrecht (Netherlands)

    1998-06-01

    Underground long-term storage of cold and heat has become a mature technique. The number of applications in the utility construction sector is growing rapidly and new areas of application come into sight. A brief overview is given of the results of some of the more than 50 projects that are carried out in different building types in the Netherlands

  11. NATO Advanced Research Workshop on Physics and Chemistry of Finite Systems : from Clusters to Crystals

    CERN Document Server

    Khanna, S; Rao, B

    1992-01-01

    Recent innovations in experimental techniques such as molecular and cluster beam epitaxy, supersonic jet expansion, matrix isolation and chemical synthesis are increasingly enabling researchers to produce materials by design and with atomic dimension. These materials constrained by sire, shape, and symmetry range from clusters containing as few as two atoms to nanoscale materials consisting of thousands of atoms. They possess unique structuraI, electronic, magnetic and optical properties that depend strongly on their size and geometry. The availability of these materials raises many fundamental questions as weIl as technological possibilities. From the academic viewpoint, the most pertinent question concerns the evolution of the atomic and electronic structure of the system as it grows from micro clusters to crystals. At what stage, for example, does the cluster look as if it is a fragment of the corresponding crystal. How do electrons forming bonds in micro-clusters transform to bands in solids? How do the s...

  12. Growing hairs in shorn cattle

    Directory of Open Access Journals (Sweden)

    Cecília José Veríssimo

    2013-12-01

    Full Text Available The shearing operation can provide double benefits to the cattle: they can become more heat tolerant and the tick infestation decreases. The cattle tick Rhipicephalus (Boophilus microplus causes great losses to dairy cattle, especially to the Holstein cattle because they are very susceptible to this tick. Its control is becoming each day more difficult, owing to the increasing resistance to acaricides they are acquiring. The objective of this work was to study the growing of haircoat following shearing. We made our experiment with 17 animals, 7 females and 10 males. They were shaved on the anterior third (head, neck, dewlap, scapula and arm of one side, at random. The work was performed in two steps: they were shorn for the first time on August 2nd 2012, with a size 10 blade in a clipper Oster model GoldenA5, which left the fur coat 2 mm long. Then we evaluated the hair length growing by collecting fortnightly three sample of hairs in the middle of the scapula, with  electric pliers, modified for this purpose, in both sides of the animals, sheared and non-sheared, until 30 days after this shearing. The three hair samples were put inside a little plastic bag per animal. Meanwhile, as we thought that the animals shearing had to be done closer to the skin, we decided to shear them again (in the same side shorn before, on October 2nd 2012. We changed our procedure using the same machine, but now with a blade size 30, which left the fur coat 1mm thick. After that, we collected again, fortnightly, samples of hairs on both sides during 2 months. The 10 longest hairs in the plastig bag were measured using a graph paper and the average per animal was calculated in each data and blade. A random design was applied for statistical analysis, the hair length of both sides, sheared and non sheared were compared by a two related samples tests – Wilcoxon, in a non parametric test, using the SPSSP 12.0 program, in each data within each blade. Using blade size

  13. Growth of single-crystal YAG fiber optics.

    Science.gov (United States)

    Nie, Craig D; Bera, Subhabrata; Harrington, James A

    2016-07-11

    Single-crystal YAG (Y3Al5O12) fibers have been grown by the laser heated pedestal growth technique with losses as low as 0.3 dB/m at 1.06 μm. These YAG fibers are as long as about 60 cm with diameters around 330 μm. The early fibers were grown from unoriented YAG seed fibers and these fibers exhibited facet steps or ridges on the surface of the fiber. However, recently we have grown fibers using an oriented seed to grow step-free fibers. Scattering losses made on the fibers indicate that the scattering losses are equal to about 30% of the total loss.

  14. Electrically Anisotropic Layered Perovskite Single Crystal

    KAUST Repository

    Li, Ting-You

    2016-04-01

    Organic-inorganic hybrid perovskites (OIHPs), which are promising materials for electronic and optoelectronic applications (1-10), have made into layered organic-inorganic hybrid perovskites (LOIHPs). These LOIHPs have been applied to thin-film transistors, solar cells and tunable wavelength phosphors (11-18). It is known that devices fabricated with single crystal exhibit the superior performance, which makes the growth of large-sized single crystals critical for future device applications (19-23). However, the difficulty in growing large-sized LOIHPs single crystal with superior electrical properties limits their practical applications. Here, we report a method to grow the centimeter-scaled LOIHP single crystal of [(HOC2H4NH3)2PbI4], demonstrating the potentials in mass production. After that, we reveal anisotropic electrical and optoelectronic properties which proved the carrier propagating along inorganic framework. The carrier mobility of in-inorganic-plane (in-plane) devices shows the average value of 45 cm2 V–1 s–1 which is about 100 times greater than the record of LOIHP devices (15), showing the importance of single crystal in device application. Moreover, the LOIHP single crystals show its ultra-short carrier lifetime of 42.7 ps and photoluminescence quantum efficiency (PLQE) of 25.4 %. We expect this report to be a start of LOIHPs for advanced applications in which the anisotropic properties are needed (24-25), and meets the demand of high-speed applications and fast-response applications.

  15. Polytypism of Pb-doped single crystals of cadmium iodide

    International Nuclear Information System (INIS)

    Tyagi, U.P.; Trigunayat, G.C.

    1986-01-01

    The zone refining technique has been used both for the purification of cadmium iodide and for the growth of lead-doped single crystals of cadmium iodide. The as-grown crystals when studied by X-ray diffraction show exclusive presence of the most common polytype 4H. The hexagonal plate-shaped crystals of the doped material, grown from aqueous solution, shown polytypism, but of a different nature than the crystals of pure cadmium iodide. The results have been discussed. (author)

  16. Macromolecule Crystal Quality Improvement in Microgravity: The Role of Impurities

    Science.gov (United States)

    Judge, Russell A.; Snell, Edward H.; Pusey, Marc L.; Sportiello, Michael G.; Todd, Paul; Bellamy, Henry; Borgstahl, Gloria E.; Pokros, Matt; Cassanto, John M.

    2000-01-01

    While macromolecule impurities may affect crystal size and morphology the over-riding question is; "How do macromolecule impurities effect crystal X-ray quality and diffraction resolution?" In the case of chicken egg white lysozyme, crystals can be grown in the presence of a number of impurities without affecting diffraction resolution. One impurity however, the lysozyme dimer, does negatively impact the X-ray crystal properties. Crystal quality improvement as a result of better partitioning of this impurity during crystallization in microgravity has been reported'. In our recent experimental work dimer partitioning was found to be not significantly different between the two environments. Mosaicity analysis of pure crystals showed a reduced mosaicity and increased signal to noise for the microgravity grown crystals. Dimer incorporation however, did greatly reduce the resolution limit in both ground and microgravity grown crystals. These results indicate that impurity effects in microgravity are complex and may rely on the conditions or techniques employed.

  17. Bridgman growth of large-aperture yttrium calcium oxyborate crystal

    International Nuclear Information System (INIS)

    Wu, Anhua; Jiang, Linwen; Qian, Guoxing; Zheng, Yanqing; Xu, Jun; Shi, Erwei

    2012-01-01

    Highlights: ► YCOB is a novel non-linear optical crystal possessing good thermal, mechanical and nonlinear optical properties. ► Large size crystal growth is key technology question for YCOB crystal. ► YCOB crystals 3 in. in diameter were grown with modified vertical Bridgman method. ► It is a more effective growth method to obtain large size and high quality YCOB crystal. -- Abstract: Large-aperture yttrium calcium oxyborate YCa 4 O(BO 3 ) 3 (YCOB) crystals with 3 in. in diameter were grown with modified vertical Bridgman method, and the large crystal plate (63 mm × 68 mm × 20 mm) was harvested for high-average power frequency conversion system. The crack, facet growth and spiral growth can be effectively controlled in the as-grown crystal, and Bridgman method displays more effective in obtain large size and high quality YCOB crystal plate than Czochralski technique.

  18. Large pyramid shaped single crystals of BiFeO{sub 3} by solvothermal synthesis method

    Energy Technology Data Exchange (ETDEWEB)

    Sornadurai, D.; Ravindran, T. R.; Paul, V. Thomas; Sastry, V. Sankara [Condensed Matter Physics Division, Materials Science Group, Physical Metallurgy Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu (India); Condensed Matter Physics Division, Materials Science Group (India)

    2012-06-05

    Synthesis parameters are optimized in order to grow single crystals of multiferroic BiFeO{sub 3}. 2 to 3 mm size pyramid (tetrahedron) shaped single crystals were successfully obtained by solvothermal method. Scanning electron microscopy with EDAX confirmed the phase formation. Raman scattering spectra of bulk BiFeO3 single crystals have been measured which match well with reported spectra.

  19. Inferring the effects of compositional boundary layers on crystal nucleation, growth textures, and mineral chemistry in natural volcanic tephras through submicron-resolution imaging

    Directory of Open Access Journals (Sweden)

    Georg F. Zellmer

    2016-09-01

    Full Text Available Crystal nucleation and growth are first order processes captured in volcanic rocks and record important information about the rates of magmatic processes and chemical evolution of magmas during their ascent and eruption. We have studied glass-rich andesitic tephras from the Central Plateau of the Southern Taupo Volcanic Zone by electron- and ion-microbeam imaging techniques to investigate down to sub-micrometre scale the potential effects of compositional boundary layers (CBLs of melt around crystals on the nucleation and growth of mineral phases and the chemistry of crystal growth zones. We find that CBLs may influence the types of mineral phases nucleating and growing, and growth textures such as the development of swallowtails. The chemistry of the CBLs also has the capacity to trigger intermittent overgrowths of nanometre-scale bands of different phases in rapidly growing crystals, resulting in what we refer to as cryptic phase zoning. The existence of cryptic phase zoning has implications for the interpretation of microprobe compositional data, and the resulting inferences made on the conditions of magmatic evolution. Identification of cryptic phase zoning may in future lead to more accurate thermobarometric estimates and thus geospeedometric constraints. In future, a more quantitative characterization of CBL formation and its effects on crystal nucleation and growth may contribute to a better understanding of melt rheology and magma ascent processes at the onset of explosive volcanic eruptions, and will likely be of benefit to hazard mitigation efforts.

  20. Bariatric amputee: A growing problem?

    Science.gov (United States)

    Kulkarni, Jai; Hannett, Dominic P; Purcell, Steven

    2015-06-01

    This study reviewed prevalence of patients with lower limb amputations with above normal weight profile, with body mass index over 25, in seven disablement services centres managing their amputee rehabilitation in the United Kingdom. To review two clinical standards of practice in amputee rehabilitation. Ambulant lower limb amputees should have their body weight recorded on an electronic information system, with identification of cohort with body weight >100 kg. Lower limb amputees to be provided with suitable weight-rated prosthesis. Observational study of clinical practice. Data were collected from the Clinical Information Management Systems. Inclusion criteria--subjects were ambulant prosthetic users with some prosthetic intervention in the last 5 years and had at least one lower limb amputation. In 96% of patients, the weight record profile was maintained. In addition, 86% were under 100 kg, which is the most common weight limit of prosthetic componentry. Of 15,204 amputation levels, there were 1830 transfemoral and transtibial sites in users with body weight over 100 kg. In 60 cases, the prosthetic limb build was rated to be below the user body weight. In 96% of our patients, body weight was documented, and in 97%, the prosthetic limb builds were within stated body weight limits, but this may not be the case in all the other disablement services centres in the United Kingdom. Also, the incidence of obesity in the United Kingdom is a growing problem, and the health issues associated with obesity are further compounded in the amputee population. Prosthetic componentry has distinct weight limits which must be considered during prescription. As people with amputation approach the limits of specific components, clinicians are faced with the challenge of continued provision in a safe and suitable manner. This article reviews the amputee population and the current national profile to consider trends in provision and the incidence of these challenges. © The

  1. Growing population causes of unemployment.

    Science.gov (United States)

    1995-01-01

    At the March, 1995, International Meeting on Population and Social Development in Copenhagen, during the session on unemployment, underemployment, and population it was stated that the problem of employment was the extent to which a nation's labor supply was not matched by labor demand or job opportunities. Population was thus a supply factor, and the country's economic situation was a demand factor. The demographic variables that were considered important in the supply of labor were: a) the size and rate of growth of the population, which was a function of the birth rate, the death rate, and migration; and b) the age structure of the population, which was also a product of the rate of growth of the population and its distribution. An imbalance between the supply of labor and the demand for it gave rise to unemployment and underemployment. The vicious cycle generated by a high dependency burden associated with a young age-structure led to low savings and investments, which in turn led to low economic growth and a low standard of living. This produced high fertility rates, which in turn heightened the dependency burden perpetuating the cycle. This vicious cycle could be broken at only two points: at the high fertility stage, primarily by introducing family planning programs; and at the stage of low economic growth, by adopting policies to accelerate economic growth. To be successful, however, both actions had to be pursued simultaneously. Numerous participants emphasized the global nature of the issue of unemployment and underemployment; the effects of international competition and restrictive trade policies on employment opportunities. The growing disparity between North and South had created a social injustice between countries. Several participants called for more humane policies that favored democracy and promoted human development, and asked for assistance to help create an enabling environment for social and economic development.

  2. Menopausal women's positive experience of growing older

    DEFF Research Database (Denmark)

    Hvas, Lotte

    2006-01-01

    This paper aims to describe menopausal women's positive experience of growing older and becoming middle-aged.......This paper aims to describe menopausal women's positive experience of growing older and becoming middle-aged....

  3. 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

  4. Binary colloidal crystals

    NARCIS (Netherlands)

    Christova-Zdravkova, C.G.

    2005-01-01

    Binary crystals are crystals composed of two types of particles having different properties like size, mass density, charge etc. In this thesis several new approaches to make binary crystals of colloidal particles that differ in size, material and charge are reported We found a variety of crystal

  5. 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

  6. Synchrotron/crystal sample preparation

    Science.gov (United States)

    Johnson, R. Barry

    1993-01-01

    The Center for Applied Optics (CAO) of the University of Alabama in Huntsville (UAH) prepared this final report entitled 'Synchrotron/Crystal Sample Preparation' in completion of contract NAS8-38609, Delivery Order No. 53. Hughes Danbury Optical Systems (HDOS) is manufacturing the Advanced X-ray Astrophysics Facility (AXAF) mirrors. These thin-walled, grazing incidence, Wolter Type-1 mirrors, varying in diameter from 1.2 to 0.68 meters, must be ground and polished using state-of-the-art techniques in order to prevent undue stress due to damage or the presence of crystals and inclusions. The effect of crystals on the polishing and grinding process must also be understood. This involves coating special samples of Zerodur and measuring the reflectivity of the coatings in a synchrotron system. In order to gain the understanding needed on the effect of the Zerodur crystals by the grinding and polishing process, UAH prepared glass samples by cutting, grinding, etching, and polishing as required to meet specifications for witness bars for synchrotron measurements and for investigations of crystals embedded in Zerodur. UAH then characterized these samples for subsurface damage and surface roughness and figure.

  7. Crystal growth and reflectivity studies of Zn1–xMnxTe crystals

    Indian Academy of Sciences (India)

    Unknown

    –2000 nm wavelength range. 3. Chemical analysis. Compositional analysis of the crystals is carried out using. EDAX technique. The average composition of the end compounds is within ± 5 % variation with respect to the target composition.

  8. Crystal modifications and dissolution rate of piroxicam.

    Science.gov (United States)

    Lyn, Lim Yee; Sze, Huan Wen; Rajendran, Adhiyaman; Adinarayana, Gorajana; Dua, Kamal; Garg, Sanjay

    2011-12-01

    Piroxicam is a nonsteroidal anti-inflammatory drug with low aqueous solubility which exhibits polymorphism. The present study was carried out to develop polymorphs of piroxicam with enhanced solubility and dissolution rate by the crystal modification technique using different solvent mixtures prepared with PEG 4000 and PVP K30. Physicochemical characteristics of the modified crystal forms of piroxicam were investigated by X-ray powder diffractometry, FT-IR spectrophotometry and differential scanning calorimetry. Dissolution and solubility profiles of each modified crystal form were studied and compared with pure piroxicam. Solvent evaporation method (method I) produced both needle and cubic shaped crystals. Slow crystallization from ethanol with addition of PEG 4000 or PVP K30 at room temperature (method II) produced cubic crystal forms. Needle forms produced by method I improved dissolution but not solubility. Cubic crystals produced by method I had a dissolution profile similar to that of untreated piroxicam but showed better solubility than untreated piroxicam. Cubic shaped crystals produced by method II showed improved dissolution, without a significant change in solubility. Based on the XRPD results, modified piroxicam crystals obtained by method I from acetone/benzene were cube shaped, which correlates well with the FTIR spectrum; modified needle forms obtained from ethanol/methanol and ethanol/acetone showed a slight shift of FTIR peak that may be attributed to differences in the internal structure or conformation.

  9. Identifying anterior segment crystals.

    OpenAIRE

    Hurley, I W; Brooks, A M; Reinehr, D P; Grant, G B; Gillies, W E

    1991-01-01

    A series of 22 patients with crystals in the anterior segment of the eye was examined by specular microscopy. Of 10 patients with hypermature cataract and hyperrefringent bodies in the anterior chamber cholesterol crystals were identified in four patients and in six of the 10 in whom aspirate was obtained cholesterol crystals were demonstrated in three, two of these having shown crystals on specular microscopy. In 10 patients with intracorneal crystalline deposits, cholesterol crystals were f...

  10. 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.

  11. Nutritional studies on growing rabbits

    International Nuclear Information System (INIS)

    Hassan, A.M.E.A.M.

    2013-01-01

    This work was carried out to study the effect of adding drinking water with either, copper sulfate, ascorbic acid or drinking cooled water on growth performance (live body weight,body weight gain, feed intake, feed conversion and water consumption), digestibility coefficients of nutrients, carcass traits, some physiological parameters and economical efficiency of growing NZW rabbits under Egyptian summer conditions. Ninety six weanling New Zealand White (NZW) male rabbits at five weeks of age and nearly similar average body weight (650.3 ±3.7 g) were randomly divided into eight treatment groups (twelve rabbits in each group), and then each group was subdivided into four replicates, each of three rabbits. The rabbits were assigned to drinking water as follow: the 1 st group was given fresh tap water without any additives as a control. The 2 n d, 3 r d and 4 t h groups were given tap fresh water supplemented with copper sulfate at levels of 40, 80 and 120 mg/L drinking water, respectively. The 5 t h, 6 t h and 7 t h groups were given tap fresh water supplemented with ascorbic acid at levels of 250, 500 and 750 mg/L drinking water, respectively. The 8 t h group was given cooled drinking water (CW) at 10-15 degree C. Results showed that supplementation of 40 or 80 mg copper sulfate/L or 500 mg ascorbic acid/L to heat-stressed rabbits drinking water improved final live body weight, body weight gain, daily water consumption, feed conversion ratio, performance index and economical efficiency. Hot carcass percentage was significantly (P<0.01) decreased with 80 mg/L copper sulfate and increased significantly (P<0.01) due to supplementation the drinking water with 250 mg ascorbic acid/L. Cooled water (10-15 degree C) improved significantly (P<0.01) each of final body weight, body weight gain, feed conversion ratio, performance index, economical efficiency and decreased significantly (P<0.01) each of hot carcass %, dressed weight %, heart %, total giblets %, rectal

  12. Synthesis, crystal growth and characterization of nonlinear optical organic crystal: p-Toluidinium p-toluenesulphonate

    International Nuclear Information System (INIS)

    Vijayakumar, P.; Anandha Babu, G.; Ramasamy, P.

    2012-01-01

    Graphical abstract: p-Toluidinium p-toluenesulphonate (p-TTS) an organic nonlinear optical crystal has been grown from the aqueous solution by slow evaporation solution growth technique. Single crystal X-ray diffraction analysis reveals that p-TTS crystallizes in monoclinic crystal system. p-TTS single crystal belongs to negative birefringence crystal. Second harmonic conversion efficiency of p-TTS has been found to be 1.3 times higher than that of KDP. Multiple shot surface laser damage threshold is determined to be 0.30 GW/cm 2 at 1064 nm laser radiation. Highlights: ► It deals with the synthesis, growth and characterization of p-TTS an organic NLO crystal. ► Wide optical transparency window between 280 nm and 1100 nm. ► Negative birefringence crystal and dispersion of birefringence is negligibly small. ► Thermal study reveals that the grown crystal is stable up to 210 °C. ► Multiple shot surface laser damage threshold is 0.30 GW/cm 2 at 1064 nm laser radiation. -- Abstract: p-Toluidinium p-toluenesulphonate (p-TTS) an organic nonlinear optical crystal has been grown from the aqueous solution by slow evaporation solution growth technique. Single crystal X-ray diffraction analysis reveals that p-TTS crystallizes in monoclinic crystal system. The structural perfection of the grown p-TTS single crystal has been analyzed by high-resolution X-ray diffraction rocking curve measurements. Fourier transform infrared spectral studies have been performed to identify the functional groups. The optical transmittance window and the lower cutoff wavelength of the grown crystals have been identified by UV–vis–IR studies. Birefringence of p-TTS crystal has been studied using channel spectrum measurement. The laser damage threshold value was measured using Nd:YAG laser. The second harmonic conversion efficiency of p-TTS has been determined using Kurtz powder technique. Thermo gravimetric and differential thermal analyses were used to study its thermal properties

  13. Crystallization and preliminary X-ray crystallographic studies of the alkanesulfonate FMN reductase from Escherichia coli

    International Nuclear Information System (INIS)

    Gao, Benlian; Bertrand, Adam; Boles, William H.; Ellis, Holly R.; Mallett, T. Conn

    2005-01-01

    Crystallization of the native and SeMet FMN reductase protein of the E. coli alkanesulfonate monooxygenase two-component enzyme system is reported. The alkanesulfonate FMN reductase (SsuE) from Escherichia coli catalyzes the reduction of FMN by NADPH to provide reduced flavin for the monooxygenase (SsuD) enzyme. The vapor-diffusion technique yielded single crystals that grow as hexagonal rods and diffract to 2.9 Å resolution using synchrotron X-ray radiation. The protein crystallizes in the primitive hexagonal space group P622. The SsuE protein lacks any cysteine or methionine residues owing to the role of the SsuE enzyme in the acquisition of sulfur during sulfate starvation. Therefore, substitution of two leucine residues (Leu114 and Leu165) to methionine was performed to obtain selenomethionine-containing SsuE for MAD phasing. The selenomethionine derivative of SsuE has been expressed and purified and crystals of the protein have been obtained with and without bound FMN. These preliminary studies should lead to the structure solution of SsuE. It is anticipated that this new protein structure will provide detailed structural information on specific active-site regions of the protein and insight into the mechanism of flavin reduction and transfer of reduced flavin

  14. Crystallization of TiO2 Nanotubes by In Situ Heating TEM

    Directory of Open Access Journals (Sweden)

    Alberto Casu

    2018-01-01

    Full Text Available The thermally-induced crystallization of anodically grown TiO2 amorphous nanotubes has been studied so far under ambient pressure conditions by techniques such as differential scanning calorimetry and in situ X-ray diffraction, then looking at the overall response of several thousands of nanotubes in a carpet arrangement. Here we report a study of this phenomenon based on an in situ transmission electron microscopy approach that uses a twofold strategy. First, a group of some tens of TiO2 amorphous nanotubes was heated looking at their electron diffraction pattern change versus temperature, in order to determine both the initial temperature of crystallization and the corresponding crystalline phases. Second, the experiment was repeated on groups of few nanotubes, imaging their structural evolution in the direct space by spherical aberration-corrected high resolution transmission electron microscopy. These studies showed that, differently from what happens under ambient pressure conditions, under the microscope’s high vacuum (p < 10−5 Pa the crystallization of TiO2 amorphous nanotubes starts from local small seeds of rutile and brookite, which then grow up with the increasing temperature. Besides, the crystallization started at different temperatures, namely 450 and 380 °C, when the in situ heating was performed irradiating the sample with electron beam energy of 120 or 300 keV, respectively. This difference is due to atomic knock-on effects induced by the electron beam with diverse energy.

  15. Crystallization of TiO2 Nanotubes by In Situ Heating TEM

    KAUST Repository

    Casu, Alberto

    2018-01-15

    The thermally-induced crystallization of anodically grown TiO2 amorphous nanotubes has been studied so far under ambient pressure conditions by techniques such as differential scanning calorimetry and in situ X-ray diffraction, then looking at the overall response of several thousands of nanotubes in a carpet arrangement. Here we report a study of this phenomenon based on an in situ transmission electron microscopy approach that uses a twofold strategy. First, a group of some tens of TiO2 amorphous nanotubes was heated looking at their electron diffraction pattern change versus temperature, in order to determine both the initial temperature of crystallization and the corresponding crystalline phases. Second, the experiment was repeated on groups of few nanotubes, imaging their structural evolution in the direct space by spherical aberration-corrected high resolution transmission electron microscopy. These studies showed that, differently from what happens under ambient pressure conditions, under the microscope’s high vacuum (p < 10−5 Pa) the crystallization of TiO2 amorphous nanotubes starts from local small seeds of rutile and brookite, which then grow up with the increasing temperature. Besides, the crystallization started at different temperatures, namely 450 and 380 °C, when the in situ heating was performed irradiating the sample with electron beam energy of 120 or 300 keV, respectively. This difference is due to atomic knock-on effects induced by the electron beam with diverse energy.

  16. Growth of K/sub 3/Li/sub 2/Nb/sub 5/O/sub 15/ and KNbO/sub 3/ ferroelectric fiber crystals by pulling-down technique

    CERN Document Server

    Chani, V I; Fukuda, T

    1998-01-01

    Growth of K/sub 3/Li/sub 2/Nb/sub 5/O/sub 15/ (KLN) and KNbO/sub 3/ (KN) crystals by the micro-pulling-down method is reported. We have systematically studied the growth conditions allowing fabrication of relatively large, macro $9 defects free, and colorless fiber crystals with pulling rate of 0.1-1.0 mm/min. The K/sub 2/O-Nb/sub 2/O/sub 5/- Li/sub 2/O ternary has been studied in the vicinity of stoichiometric compositions of K/sub 3/Li/sub 2/Nb/sub 5/O/sub $9 15/ and KNbO/sub 3/. KLN and KN phase fields have been identified by direct growth experiments. It was found that addition of 1-6 mol.554330f Li/sub 2/O into the KNbO/sub 3/ melt avoids K/sub 4/Nb/sub 6/O/sub 17/ second phase $9 formation and decreases blue coloration of the KN crystals. Growth of Ta-substituted KLN and KN crystals is also reported. (14 refs).

  17. Multifunctional Bi{sub 2}ZnOB{sub 2}O{sub 6} single crystals for second and third order nonlinear optical applications

    Energy Technology Data Exchange (ETDEWEB)

    Iliopoulos, K. [LUNAM Université, Université d' Angers, CNRS UMR 6200, Laboratoire MOLTECH-Anjou, 2 Bd Lavoisier, 49045 Angers Cedex (France); Institute of Chemical Engineering Sciences, Foundation for Research and Technology Hellas (FORTH/ICE-HT), 26504 Patras (Greece); Kasprowicz, D. [Faculty of Technical Physics, Poznan University of Technology, Nieszawska 13 A, 60-965 Poznan (Poland); Majchrowski, A. [Institute of Applied Physics, Military University of Technology, Kaliskiego 2, 00-908 Warszawa (Poland); Michalski, E. [Institute of Optoelectronics, Military University of Technology, Kaliskiego 2, 00-908 Warszawa (Poland); Gindre, D.; Sahraoui, B., E-mail: bouchta.sahraoui@univ-angers.fr [LUNAM Université, Université d' Angers, CNRS UMR 6200, Laboratoire MOLTECH-Anjou, 2 Bd Lavoisier, 49045 Angers Cedex (France)

    2013-12-02

    Bi{sub 2}ZnOB{sub 2}O{sub 6} nonlinear optical single crystals were grown by means of the Kyropoulos method from stoichiometric melt. The second and third harmonic generation (SHG/THG) of Bi{sub 2}ZnOB{sub 2}O{sub 6} crystals were investigated by the SHG/THG Maker fringes technique. Moreover, SHG microscopy studies were carried out providing two-dimensional SHG images as a function of the incident laser polarization. The high nonlinear optical efficiency combined with the possibility to grow high quality crystals make Bi{sub 2}ZnOB{sub 2}O{sub 6} an excellent candidate for photonic applications.

  18. Crystallization and preliminary X-ray diffraction analysis of recombinant phosphoribosylpyrophosphate synthetase from the Thermophilic thermus thermophilus strain HB27

    Energy Technology Data Exchange (ETDEWEB)

    Abramchik, Yu. A. [Russian Academy of Sciences, Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry (Russian Federation); Timofeev, V. I., E-mail: tostars@mail.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography of Federal Scientific Research Centre “Crystallography and Photonics” (Russian Federation); Muravieva, T. I.; Sinitsyna, E. V.; Esipov, R. S., E-mail: esipov@mx.ibch.ru [Russian Academy of Sciences, Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry (Russian Federation); Kuranova, I. P., E-mail: inna@ns.crys.ras.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography of Federal Scientific Research Centre “Crystallography and Photonics” (Russian Federation)

    2017-01-15

    Phosphoribosylpyrophosphate synthetases (PRPP synthetases) are among the key enzymes essential for vital functions of organisms and are involved in the biosynthesis of purine and pyrimidine nucleotides, coenzymes, and the amino acids histidine and tryptophan. These enzymes are used in biotechnology for the combined chemoenzymatic synthesis of natural nucleotide analogs. Recombinant phosphoribosylpyrophosphate synthetase I from the thermophilic strain HB27 of the bacterium Thermus thermophilus (T. th HB27) has high thermal stability and shows maximum activity at 75°Ð¡, due to which this enzyme holds promise for biotechnological applications. In order to grow crystals and study them by X-ray crystallography, an enzyme sample, which was produced using a highly efficient producer strain, was purified by affinity and gel-filtration chromatography. The screening of crystallization conditions was performed by the vapor-diffusion technique. The crystals of the enzyme suitable for X-ray diffraction were grown by the counter-diffusion method through a gel layer. These crystals were used to collect the X-ray diffraction data set at the SPring-8 synchrotron radiation facility (Japan) to 3-Å resolution. The crystals belong to sp. gr. P2{sub 1} and have the following unitcell parameters: a = 107.7 Å, b = 112.6 Å, c = 110.2 Å, α = γ = 90°, β = 116.6°. The X-ray diffraction data set is suitable for determining the three-dimensional structure of the enzyme at 3.0-Å resolution.

  19. Growing your green chemistry mindset

    Science.gov (United States)

    Kosmas, Steven

    2017-08-01

    The purpose of this article is not to delineate the steps to move across the continuum to being a greener chemist, but to analyse the cognitive processes involved in fostering a green chemistry growth mindset (GCGM) [Dweck C. (2006) Mindset: The New Psychology of Success. New York, NY: Ballatine]. The focus is on changing the mindset, which inevitably will lead to a more mindful approach to chemistry practices before the laboratory begins. A green chemistry fixed mindset (GCFM) is closed to making improvements, since the attitude is that the techniques and processes in the laboratory are already employing a green chemistry mindset [Dweck C. (2006) Mindset: The New Psychology of Success. New York, NY: Ballatine]. The problem with the GCFM is that it precludes the possibility of making improvements. However, the GCGM employs a continuous, intentional focus on the attitude towards green chemistry, with the ultimate goal being a change in chemistry practices that is greener. The focus of this article will be on the GCGM.

  20. 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...

  1. 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.

  2. Photonic crystals physics, fabrication and applications

    CERN Document Server

    Ohtaka, Kazuo

    2004-01-01

    "Photonic Crystals" details recent progress in the study of photonic crystals, ranging from fundamental aspects to up-to-date applications, in one unified treatment It covers most of the worldwide frontier fields in photonic crystals, including up-to-date fabrication techniques, recent and future technological applications, and our basic understanding of the various optical properties of photonic crystals Brand-new theoretical and experimental data are also presented The book is intended for graduate course students and specialists actively working in this field, but it will also be useful for newcomers, especially the extensive chapter dealing with fundamental aspects of photonic crystals, which paves the way to a full appreciation of the other topics addressed

  3. Crystal nucleation of colloidal hard dumbbells.

    Science.gov (United States)

    Ni, Ran; Dijkstra, Marjolein

    2011-01-21

    Using computer simulations, we investigate the homogeneous crystal nucleation in suspensions of colloidal hard dumbbells. The free energy barriers are determined by Monte Carlo simulations using the umbrella sampling technique. We calculate the nucleation rates for the plastic crystal and the aperiodic crystal phase using the kinetic prefactor as determined from event driven molecular dynamics simulations. We find good agreement with the nucleation rates determined from spontaneous nucleation events observed in event driven molecular dynamics simulations within error bars of one order of magnitude. We study the effect of aspect ratio of the dumbbells on the nucleation of plastic and aperiodic crystal phases, and we also determine the structure of the critical nuclei. Moreover, we find that the nucleation of the aligned close-packed crystal structure is strongly suppressed by a high free energy barrier at low supersaturations and slow dynamics at high supersaturations.

  4. Cultivation of fast-growing hardwoods

    Energy Technology Data Exchange (ETDEWEB)

    White, E.H.; Abrahamson, L.P. (State Univ. of New York, Syracuse, NY (United States). Coll. of Environmental Science and Forestry)

    1991-10-01

    The intensive culture of hybrid poplar has received in-depth study as part of the Fast-Growing Hardwood Program. Research has concentrated on short-rotation intensive culture systems. Specific studies and operations included establishing and maintaining a nursery/cutting orchard, installing clone-site trials in central and southern New York State and initiating studies of no-till site preparation, nutrient utilization efficiency, wood quality and soil solution chemistry. The nursery/cutting orchard was used to provide material for various research plantings and as a genotype repository. Clone- site trials results showed that hybrid poplar growth potential was affected by clone type and was related to inherent soil-site conditions. No-till techniques were shown to be successful in establishing hybrid poplar in terms of survival and growth when compared to conventional clean tillage and/or no competition control, and can be considered for use on sites that are particularly prone to erosion. Nutrient use efficiency was significantly affected by clone type, and should be a consideration when selecting clones for operational planting if fertilization is to be effectively and efficiently used. Wood quality differed among clones with site condition and tree age inferred as important factors. Soil solution chemistry was minimally affected by intensive cultural practices with no measured adverse effect on soil water quality. Generally, results of these studies showed that appropriate hybrid poplar clones grown in short-rotation intensively cultured systems can be used successfully in New York State if proper site conditions exist and appropriate establishment and maintenance techniques are used. 37 refs., 4 figs., 22 tabs.

  5. Single-crystal growth of ceria-based materials

    International Nuclear Information System (INIS)

    Ulbrich, Gregor

    2015-01-01

    In this work it could be shown that Skull-Melting is a suitable method for growing ceria single crystals. Twenty different ceria-based single crystals could be manufactured. It was possible to dope ceria single crystals with Gd, Sm, Y, Zr, Ti, Ta, and Pr in different concentrations. Also co-doping with the named metals was realized. However, there remain some problems for growing ceria-based single crystals by Skull-Melting. As ignition metal zirconium was used because no ceria-based material works well. For that reason all single crystals show small zirconium contamination. Another problem is the formation of oxygen by the heat-induced reduction of ceria during the melting process. Because of that the skull of sintered material is often destroyed by gas pressure. This problem had to be solved individually for every single crystal. The obtained single crystals were characterized using different methods. To ensure the single crystal character the y were examined by Laue diffraction. All manufactured crystals are single crystals. Also powder diffraction patterns of the milled and oxidized samples were measured. For the determination of symmetry and metric the structural parameters were analyzed by the Rietveld method. All synthesized materials crystallize in space group Fm-3m known from calcium fluoride. The cubic lattice parameter a was determined for all crystals. In the case of series with different cerium and zirconium concentrations a linear correlation between cerium content and cubic lattice parameter was detected. The elemental composition was determined by WDX. All crystals show a homogeneous elemental distribution. The oxygen content was calculated because the WDX method isn't useful for determination.

  6. Critical size for the grow of phases under irradiation: an example

    International Nuclear Information System (INIS)

    Sarce, Alicia

    1999-01-01

    The critical sizes d * a,c in the a and c-crystal directions for the grow of bcc β-85 wt % Nb precipitates in the hcp α-Zr (1 wt % Nb) matrix are calculated. The atomic interactions in the hcp α-Zr are represented with a many-body potential EAM2 based on the embedded atom method. The anisotropy of the diffusion of vacancies and interstitials in the lattice is explicitly included in calculations. The results are obtained at 560 K and at a displacement rate of about 1.4x10 -7 dpa/s. It is predicted that all particles will be able to grow in the plane perpendicular to c-crystal direction. Also, the particles could grow in this direction if the size d c > d * c . Then, the precipitates will have only a slightly anisotropic shape, with the smaller size parallel to c. (author)

  7. Ecogeomorphic Feedbacks that Grow Deltas

    Science.gov (United States)

    Ma, H.; Larsen, L.; Wagner, W.

    2017-12-01

    Coastal river deltas are complex and dynamic ecosystems where vegetation plays an essential role in influencing (as well as being influenced by) physical processes, creating a strong potential for ecogeomorphic feedbacks. However, understanding of the relative strenghts of feedback between vegetation species and topography along different portions of the marsh elevation/zonation gradient is poorly developed, particularly for freshwater, deltaic marshes. In part, this knowledge gap is due to difficulties associated with adequate sampling within heterogeneous vegetation communities to delineate bi-directional feedback applicable at the delta scale.. Emerging technology (high resolution remote sensing and high resolution LiDAR) and data analysis techniques like transfer entropy have made it possible to overcome these difficulties. Here, results of the transfer entropy analysis were consistent with widespread understanding of marsh zonation, yet produced additional insight into which vegetation communities specifically had a dominant impact on topographic change. Ecogeomorphic feedback that has a substantial short-term impact on evolving topography was resolvable only within native vegetation communities (Nelumbo lutea and Polygonum spp.) that occur over low to moderate elevations within the Wax Lake Delta tidal prism. In contrast, nonnative vegetation communities (Colocasia esculenta and Eichhonia crasspies) are not as functional at accreting sediment as native communities. The transfer entropy analysis suggests that different vegetation communities play functionally different roles in landscape evolution that should be differentiated in a model. Within such a model, it would be most critical to resolve detailed flow characteristics at low to low-middle island elevations, where submerged aquatic vegetation and Nelumbo are abundant, as these communities exert the strongest influence on topographic change. Furthermore, within elevation zones, it is likely important to

  8. Studies on crystal growth and physical properties of 4-(dimethylamino)benzaldehyde-2,4-dinitroaniline single crystal

    Science.gov (United States)

    Jebin, R. P.; Suthan, T.; Rajesh, N. P.; Vinitha, G.; Dhas, S. A. Britto

    2016-07-01

    The organic material 4-(dimethylamino)benzaldehyde-2,4-dinitroaniline has been grown by slow evaporation technique. Single crystal and Powder X-ray diffraction studies have been carried out to conform the grown crystal. FTIR and FT-Raman spectra were recorded to identify the functional groups present in the crystal. The optical property of the grown crystal was analysed by UV-Vis-NIR measurement. The thermal property of the grown crystal was analysed by thermogravimetric (TG) and differential thermal analyses (DTA). Thermal diffusivity of the grown crystal was analysed by Photo acoustic spectroscopic (PAS) studies. The third order nonlinear optical properties of 4-(dimethylamino)benzaldehyde-2,4-dinitroaniline was measured by the Z-scan technique using 532 nm diode pumped continuous wave (CW) Nd:YAG laser. The mechanical property of the grown crystal was analysed by using microhardness studies.

  9. Advances in crystal growth, device fabrication and characterization of thallium bromide detectors for room temperature applications

    Science.gov (United States)

    Datta, Amlan; Moed, Demi; Becla, Piotr; Overholt, Matthew; Motakef, Shariar

    2016-10-01

    Thallium bromide (TlBr) is a promising room-temperature radiation detector candidate with excellent charge transport properties. However, several critical issues need to be addressed before deployment of this material for long-term field applications can be realized. In this paper, progress made towards solving some of these challenges is discussed. The most significant factors for achieving long-term performance stability for TlBr devices include residual stress as generated during crystal growth and fabrication processes, surface conditions, and the choice of contact metal. Modifications to the commonly used traveling molten zone growth technique for TlBr crystals can significantly minimize the stresses generated by large temperature gradients near the melt-solid interface of the growing crystal. Plasma processing techniques were introduced for the first time to modify the Br-etched TlBr surfaces, which resulted in improvements to the surface conditions, and consequently the spectroscopic response of the detectors. Palladium electrodes resulted a 20-fold improvement in the room-temperature device lifetime when compared to its Br-etched Pt counterpart.

  10. Implementation of Temperature-Controlled Method of Protein Crystallization in Microgravity

    Science.gov (United States)

    Strelov, V. I.; Zakharov, B. G.; Bezbakh, I. Zh.; Safronov, V. V.; Chernyshev, B. V.; Dutyshev, I. N.

    2018-01-01

    An experimental scientific equipment for implementing temperature-controlled protein crystallization in capillaries under microgravity has been developed, fabricated, and tested. This crystallization method, providing on-line separate control of crystal growth both in the stage of nucleation of crystals and during their further growth, requires small amounts of protein solution. The equipment has been tested on board of Foton-M4 spacecraft (growth of lysozyme protein crystals of high structural quality in microgravity) using a cyclogram developed in ground-based experiments. The results obtained have demonstrated efficiency and importance of the developed equipment and method for growing biomacromolecular crystals of high-structural quality.

  11. 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.

  12. Solution-Phase Processes of Macromolecular Crystallization

    Science.gov (United States)

    Pusey, Marc L.; Minamitani, Elizabeth Forsythe

    2004-01-01

    We have proposed, for the tetragonal form of chicken egg lysozyme, that solution phase assembly processes are needed to form the growth units for crystal nucleation and growth. The starting point for the self-association process is the monomeric protein, and the final crystallographic symmetry is defined by the initial dimerization interactions of the monomers and subsequent n-mers formed, which in turn are a function of the crystallization conditions. It has been suggested that multimeric proteins generally incorporate the underlying multimers symmetry into the final crystallographic symmetry. We posed the question of what happens to a protein that is known to grow as an n-mer when it is placed in solution conditions where it is monomeric. The trypsin-treated, or cut, form of the protein canavalin (CCAN) has been shown to nucleate and grow crystals as a trimer from neutral to slightly acidic solutions. Under these conditions the solution is composed almost wholly of trimers. The insoluble protein can be readily dissolved by weakly basic solution, which results in a solution that is monomeric. There are three possible outcomes to an attempt at crystallization of the protein under monomeric (high pH) conditions: 1) we will obtain the same crystals as under trimer conditions, but at different protein concentrations governed by the self association equilibria; 2) we will obtain crystals having a different symmetry, based upon a monomeric growth unit; 3) we will not obtain crystals. Obtaining the first result would be indicative that the solution-phase self-association process is critical to the crystal nucleation and growth process. The second result would be less clear, as it may also reflect a pH-dependent shift in the trimer-trimer molecular interactions. The third result, particularly for experiments in the transition pH's between trimeric and monomeric CCAN, would indicate that the monomer does not crystallize, and that solution phase self association is not part

  13. Discovery Mondays: crystals and particles for medicine

    CERN Document Server

    2003-01-01

    Question: what are as heavy as lead, as clear as glass, and appear as tiny specks in a doctor's scanner but large as life in a physicist's detector? Answer: the crystals you will be able to observe in all their facets on 1 September at the start of a new season of Discovery Mondays at Microcosm. Come along and meet the CERN physicists who use crystals not only in their detectors but also in the latest generation of scanners. Four workshops will be organised, each devoted to a different medical imaging technique. The first workshop will be run by a physicist from the Crystal Clear collaboration, who will present her collaboration's special breed of crystals, which emit light when they are traversed by high-energy particles, and explain to you these crystals' role in Positron Emission Tomographs. The second workshop will focus on an imaging technique known as the Compton Camera, also based on scintillating crystals. Crystals worth looking at and admiring. Come to the next Discovery Monday to find out how they ...

  14. Hanging drop crystal growth apparatus

    Science.gov (United States)

    Naumann, Robert J. (Inventor); Witherow, William K. (Inventor); Carter, Daniel C. (Inventor); Bugg, Charles E. (Inventor); Suddath, Fred L. (Inventor)

    1990-01-01

    This invention relates generally to control systems for controlling crystal growth, and more particularly to such a system which uses a beam of light refracted by the fluid in which crystals are growing to detect concentration of solutes in the liquid. In a hanging drop apparatus, a laser beam is directed onto drop which refracts the laser light into primary and secondary bows, respectively, which in turn fall upon linear diode detector arrays. As concentration of solutes in drop increases due to solvent removal, these bows move farther apart on the arrays, with the relative separation being detected by arrays and used by a computer to adjust solvent vapor transport from the drop. A forward scattering detector is used to detect crystal nucleation in drop, and a humidity detector is used, in one embodiment, to detect relative humidity in the enclosure wherein drop is suspended. The novelty of this invention lies in utilizing angular variance of light refracted from drop to infer, by a computer algorithm, concentration of solutes therein. Additional novelty is believed to lie in using a forward scattering detector to detect nucleating crystallites in drop.

  15. The effect of lumbosacral manipulation on growing pains

    Directory of Open Access Journals (Sweden)

    Dawid de Beer

    2015-10-01

    Objective: The aim of this study was to determine whether lumbosacral manipulations have an effect on growing pain symptoms. Methods: Thirty participants with growing pains between the ages of 4 and 12 years were recruited. The participants were placed into two groups of 15 participants each. Group 1 received lumbosacral manipulations to restricted joints as determined by motion palpation, while Group 2 never received any professional intervention. Often parent(s/guardian(s of children who suffer from growing pains will rub the child's legs and offer verbal reassurance in an attempt to console their children. Parent(s/guardian(s of both groups were encouraged to continue to do this throughout the duration of the trial. Instructions were given to the parents so that the same rubbing technique and rubbing cream (aqueous cream were used. Subjective changes were tracked using a pain diary that the parent(s/guardian(s were asked to complete, a six-week post-study follow-up question regarding children's growing pains and the Oucher self-report pain scale. Objective measures consisted of pressure algometer readings of the tibialis anterior muscle belly. Results: The statistical data was analysed using the Friedman test, Manne—Whitney test and the Wilcoxon Signed-Rank test. The results demonstrated that both groups responded favourably to their specific treatment over time. However, the group that received lumbosacral manipulations proved to show a quicker response to treatment; and the post study follow-up of this same group showed markedly more positive feedback than the group that did not receive the treatment. These results highlighted the positive effects of chiropractic manipulation on growing pain symptoms. Conclusion: The results from this study, specifically the feedback from parent(s/guardians(s and the pain diaries, indicated that spinal manipulation is beneficial in the treatment of growing pains. The results also showed that other methods of treating growing

  16. Investigation of calcium crystals in OA knees.

    Science.gov (United States)

    Fuerst, Martin; Lammers, L; Schäfer, F; Niggemeyer, O; Steinhagen, J; Lohmann, C H; Rüther, W

    2010-03-01

    For studies on matrix mineralization in osteoarthritis (OA), a clear analytical approach is necessary to identify and to quantify mineralization in the articular cartilage. The aim of this study is to develop an effective algorithm to quantify and to identify cartilage mineralization in the experimental setting. Four patients with OA of the knee undergoing total knee replacement and four control patients were included. Cartilage calcification was studied by digital contact radiography (DCR), field emission scanning electron microscopy (FE-SEM) X-ray element analysis and Raman spectroscopy (RS). DCR revealed mineralization in all OA cartilage specimens. No mineralization was observed in the control cartilage. Patient I showed rhomboid shaped crystals with a mean Ca:P molar ratio of 1.04 indicated the presence of calcium pyrophosphate dihydrate (CPPD) crystals, while Patients II, III and IV presented carbonate-substituted hydroxyapatite (HA). RS also showed the presence of CPPD crystals in Patient I while Patients II, III and IV revealed spectra confirming the presence of HA crystals. In the corresponding chondrocyte cell culture analyzed with SEM, the presence of CPPD crystals in the culture of Patient I and HA crystals in the culture of Patient II, III and IV was confirmed. No mineralization was found in the cell culture of the controls. The differentiation between BCP and CPPD crystals plays an important role, and the techniques presented here provide an accurate differentiation of these two types of crystals. For quantification of articular cartilage mineralization, DCR is a simple and accurate method.

  17. SAR Imagery Segmentation by Statistical Region Growing and Hierarchical Merging

    Energy Technology Data Exchange (ETDEWEB)

    Ushizima, Daniela Mayumi; Carvalho, E.A.; Medeiros, F.N.S.; Martins, C.I.O.; Marques, R.C.P.; Oliveira, I.N.S.

    2010-05-22

    This paper presents an approach to accomplish synthetic aperture radar (SAR) image segmentation, which are corrupted by speckle noise. Some ordinary segmentation techniques may require speckle filtering previously. Our approach performs radar image segmentation using the original noisy pixels as input data, eliminating preprocessing steps, an advantage over most of the current methods. The algorithm comprises a statistical region growing procedure combined with hierarchical region merging to extract regions of interest from SAR images. The region growing step over-segments the input image to enable region aggregation by employing a combination of the Kolmogorov-Smirnov (KS) test with a hierarchical stepwise optimization (HSWO) algorithm for the process coordination. We have tested and assessed the proposed technique on artificially speckled image and real SAR data containing different types of targets.

  18. Rotary forcespun styrofoam fibers as a soilless growing medium

    Science.gov (United States)

    Fauzi, Ahmad; Edikresnha, Dhewa; Munir, Muhammad Miftahul; Khairurrijal

    2016-04-01

    To make styrofoam fibers from used styrofoam, rotary forcespinning technique was used because it offers high production rate and affordable production cost. The used styrofoam was dissolved in acetone to obtain styrofoam solution as a precursor of syrofoam fibers. Since the technique utilizes centrifugal force, the precursor was thrown out and its phase changed to be solid following acetone solvent evaporation. Long, clean and light styrofoam fibers were then produced. To determine if the styrofoam fibers is a good soilless growing medium, physico-chemical properties including pH and electrical conductivity, bulk density, water retention and wettability were measured. Rockwool, which is the most popular soilless growing medium and easily obtained from local farm suppliers, was selected as a benchmark to evaluate the styrofoam fibers.

  19. 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...

  20. Crystal structure and prediction.

    Science.gov (United States)

    Thakur, Tejender S; Dubey, Ritesh; Desiraju, Gautam R

    2015-04-01

    The notion of structure is central to the subject of chemistry. This review traces the development of the idea of crystal structure since the time when a crystal structure could be determined from a three-dimensional diffraction pattern and assesses the feasibility of computationally predicting an unknown crystal structure of a given molecule. Crystal structure prediction is of considerable fundamental and applied importance, and its successful execution is by no means a solved problem. The ease of crystal structure determination today has resulted in the availability of large numbers of crystal structures of higher-energy polymorphs and pseudopolymorphs. These structural libraries lead to the concept of a crystal structure landscape. A crystal structure of a compound may accordingly be taken as a data point in such a landscape.

  1. 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.

  2. SCIENTIFIC SUPPORT OF VEGETABLE, MELON, AND POTATO GROWING IN RUSSIA

    Directory of Open Access Journals (Sweden)

    I. V. Savchenko

    2013-01-01

    Full Text Available The summary report of research investigations of the institutes of the Russian Academy of Agricultural Science, the Russian Academy of Science, and the Institutions of Higher Education in 2013 on the project «Development of new varieties and high-precision sustainable zonal technologies of vegetable and cucurbits crops growing with the use of new varieties and hybrids, high'quality seeds, advanced approaches of agro-techniques, plant protection, and mechanical equipments» is represented.

  3. Preparing polished crystal slices with high precision orientation

    DEFF Research Database (Denmark)

    Mathiesen, S. Ipsen; Gerward, Leif; Pedersen, O.

    1974-01-01

    A polishing procedure is described which utilizes a high precision Laue technique for crystal orientation. Crystal slices with their final polished surfaces parallel to a crystallographic plane within 0.02° can be prepared. ©1974 The American Institute of Physics......A polishing procedure is described which utilizes a high precision Laue technique for crystal orientation. Crystal slices with their final polished surfaces parallel to a crystallographic plane within 0.02° can be prepared. ©1974 The American Institute of Physics...

  4. General approach to Monte Carlo simulation of crystal growth

    International Nuclear Information System (INIS)

    Cherepanova, T.A.

    1986-01-01

    This paper presents a statistical-mechanic description of the techniques valid for simulating crystal growth both in single-component and in multi-component crystals, the work being based on the ideas previously developed. A lattice model of a two-phase crystal-melt system is considered. The authors consider general features of crystallization in metal type bindary systems (growth on atomically rough (001) faces) by using simulation techniques and by solving kinetic equations. They choose as a model those systems with primitive cubic lattice symmetry

  5. Pulse holographic measurement techniques

    International Nuclear Information System (INIS)

    Kim, Cheol Jung; Baik, Seong Hoon; Hong, Seok Kyung; Kim, Jeong Moog; Kim, Duk Hyun

    1992-01-01

    With the development of laser, remote inspection techniques using laser have been growing on. The inspection and measurement techniques by pulse holography are well-established technique for precise measurement, and widely used in various fields of industry now. In nuclear industry, this technology is practically used because holographic inspection is remote, noncontact, and precise measurement technique. In relation to remote inspection technology in nuclear industry, state-of-the art of pulse HNDT (Holographic non-destructive testing) and holographic measurement techniques are examined. First of all, the fundamental principles as well as practical problems for applications are briefly described. The fields of pulse holography have been divided into the HNDT, flow visualization and distribution study, and other application techniques. Additionally holographic particle study, bubble chamber holography, and applications to other visualization techniques are described. Lastly, the current status for the researches and applications of pulse holography to nuclear industry which are carried out actively in Europe and USA, is described. (Author)

  6. 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.

  7. 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

  8. Analysis of liquid crystal properties for photonic crystal fiber devices

    DEFF Research Database (Denmark)

    Weirich, Johannes; Lægsgaard, Jesper; Wei, Lei

    2009-01-01

    We analyze the bandgap structure of Liquid Crystal infiltrated Photonic Crystal Fibers depending on the parameters of the Liquid Crystals by means of finite element simulations. For a biased Liquid Crystal Photonic Crystal Fiber, we show how the tunability of the bandgap position depends...... on the Liquid Crystal parameters....

  9. Model-Based Control of Industrial Batch Crystallizers : Experiments on Enhanced Controllability by Seeding Actuation

    NARCIS (Netherlands)

    Kalbasenka, A.N.

    2009-01-01

    Crystallization is one of the oldest separation and purification techniques. Batch crystallizers are widely used in production of fine chemicals, food ingredients, specialty chemicals, and active pharmaceutical ingredients. Control of the crystalline material properties is a challenging task due to

  10. Response of growing bones to irradiation

    International Nuclear Information System (INIS)

    Gonzalez Gonzalez, D.

    1980-01-01

    This thesis describes the effects of ionizing radiations on growing bones. The epiphyseal disc of growing mouse tibia was selected as a model for the experiments. An attempt has been made to obtain clinical data from irradiated bones during the childhood and to quantitate this information. Within the range of possibilities correlations have been established between the experimental and clinical data. (Auth.)

  11. Geometric Growing Patterns: What's the Rule?

    Science.gov (United States)

    Hourigan, Mairéad; Leavy, Aisling

    2015-01-01

    While within a geometric repeating pattern, there is an identifiable core which is made up of objects that repeat in a predictable manner, a geometric growing pattern (also called visual or pictorial growing patterns in other curricula) "is a pattern that is made from a sequence of figures [or objects] that change from one term to the next in…

  12. Locating and Visualizing Crystals for X-Ray Diffraction Experiments.

    Science.gov (United States)

    Becker, Michael; Kissick, David J; Ogata, Craig M

    2017-01-01

    Macromolecular crystallography has advanced from using macroscopic crystals, which might be >1 mm on a side, to crystals that are essentially invisible to the naked eye, or even under a standard laboratory microscope. As crystallography requires recognizing crystals when they are produced, and then placing them in an X-ray, electron, or neutron beam, this provides challenges, particularly in the case of advanced X-ray sources, where beams have very small cross sections and crystals may be vanishingly small. Methods for visualizing crystals are reviewed here, and examples of different types of cases are presented, including: standard crystals, crystals grown in mesophase, in situ crystallography, and crystals grown for X-ray Free Electron Laser or Micro Electron Diffraction experiments. As most techniques have limitations, it is desirable to have a range of complementary techniques available to identify and locate crystals. Ideally, a given technique should not cause sample damage, but sometimes it is necessary to use techniques where damage can only be minimized. For extreme circumstances, the act of probing location may be coincident with collecting X-ray diffraction data. Future challenges and directions are also discussed.

  13. A Novel Approach to Solving the Problem of Needle Microcrystals (A Case Study of Ribosome Crystals)

    Science.gov (United States)

    Karpova, Elizaveta A.; Tarahovsky, Yuri S.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Different morphology crystals (needle, rod-tetragonal and wedge-shaped) were grown from the same solution of ribosome; furthermore, in the same drop using 10- 15% 2-methyl-2,4pentanediol as a precipitant. The crystals appeared in 5-48 hours. Observations of the kinetics of crystals appearance lead to the conclusion that higher supersaturation of ribosome solution produces needle-shaped crystals, while the tetragonal-rod and the wedge-shaped crystals grow at lower supersaturation. The ribosome packing in the crystals was characterized by electron microscopy (EM). An analysis of EM ultrathin sections indicates that the unit cells, with a high degree of probability, are the same in the crystals of different morphology. The data obtained suggests how to shift the process of crystal formation from the needles to the crystals with comparative size in all three dimensions.

  14. Protein synthesis in the growing rat lung

    International Nuclear Information System (INIS)

    Kelley, J.; Chrin, L.

    1986-01-01

    Developmental control of protein synthesis in the postnatal growth of the lung has not been systematically studied. In male Fischer 344 rats, lung growth continues linearly as a function of body weight (from 75 to 450 g body weight). To study total protein synthesis in lungs of growing rats, we used the technique of constant intravenous infusion of tritiated leucine, an essential amino acid. Lungs of sacrificed animals were used to determine the leucine incorporation rate into newly synthesized protein. The specific radioactivity of the leucine associated with tRNA extracted from the same lungs served as an absolute index of the precursor leucine pool used for lung protein synthesis. On the basis of these measurements, we were able to calculate the fractional synthesis rate (the proportion of total protein destroyed and replaced each day) of pulmonary proteins for each rat. Under the conditions of isotope infusion, leucyl-tRNA very rapidly equilibrates with free leucine of the plasma and of the extracellular space of the lung. Infusions lasting 30 minutes or less yielded linear rates of protein synthesis without evidence of contamination of lung proteins by newly labeled intravascular albumin. The fractional synthesis rate is considerably higher in juvenile animals (55% per day) than in adult rats (20% per day). After approximately 12 weeks of age, the fractional synthesis rate remains extremely constant in spite of continued slow growth of the lung. It is apparent from these data that in both young and adult rats the bulk of total protein synthesis is devoted to rapidly turning over proteins and that less than 4 percent of newly made protein is committed to tissue growth

  15. 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.

  16. Reductive methylation to improve crystallization of the putative oxidoreductase Rv0765c from Mycobacterium tuberculosis

    International Nuclear Information System (INIS)

    Rauert, Wilko; Eddine, Ali Nasser; Kaufmann, Stefan H. E.; Weiss, Manfred S.; Janowski, Robert

    2007-01-01

    The M. tuberculosis protein Rv0765c was cloned, expressed, purified and crystallized. In an attempt to improve the quality of the crystals of Rv0765c, the protein was modified by reductive methylation. The methylated protein crystallized in a new crystal form with profoundly improved diffraction properties. Rv0765c from Mycobacterium tuberculosis was cloned and heterologously expressed in Escherichia coli. It was purified using affinity and size-exclusion chromatographic techniques and crystallized. The native protein crystallized in a hexagonal crystal form which diffracted to 7 Å resolution. In an attempt to improve the quality of the Rv0765c crystals, the protein was modified by reductive methylation using dimethylaminoborane and formaldehyde. The modified protein crystallized under different conditions in a tetragonal crystal form, from which diffraction data could be collected to a resolution of 3.2 Å. In both crystal forms of Rv0765c, the asymmetric unit contained two copies of the protein molecule

  17. Absorción de nutrientes en Zantedeschia elliottiana variedad Cristal Blush y su relación con la producción de biomasa en condiciones de la zona cafetera de Colombia Absorption of nutrients in Zantedeschia elliottiana Crystal Blush and its relationship with biomass production in the Colombian coffee-growing conditions

    Directory of Open Access Journals (Sweden)

    Susana Gómez

    2010-10-01

    Full Text Available En un cultivo comercial del municipio de Pereira, Risaralda, se evaluó la extracción de nutrientes de Zantedeschia elliottiana variedad Cristal Blush y su relación con la acumulación de materia seca y la producción de tallos florales y bulbos durante el primer ciclo de producción. Se utilizó un diseño bloques completos al azar con cuatro tratamientos correspondientes a diferentes niveles de fertilización y tres repeticiones. Se caracterizaron los cambios en la concentración de nutrientes en bulbos y parte aérea de la planta en cada etapa de desarrollo mediante muestreo destructivo de tejidos a 28, 49, 63, 77, 98 y 140 días después de la siembra. Las concentraciones de N, Ca, Mg y B en bulbo y las concentraciones foliares de N, Mg y Cu en la época de floración inciden directamente sobre el número de tallos comerciales, mientras que los contenidos a nivel foliar de Ca, Mg y S durante las semanas 7 a 10 inciden directamente sobre el porcentaje de tuberización. Para obtener una producción de 160 tallos comerciales/m² y 21.7 t/ha de bulbos, es necesario aplicar (kg/ha: 248(N, 42(P, 305(K, 103(Ca, 21(Mg y 33(S.In a commercial crop in the municipality of Pereira, Risaralda, Colombia, it was assessed the nutrient extraction of Zantedeschia elliottiana 'Crystal Blush' and its relation to dry matter accumulation and production of flower stalks and bulbs during the first production cycle. We used a randomized complete block design (RCBD with 4 treatments corresponding to different levels of fertilization and three replications, characterizing changes in the concentration of nutrients in bulbs and aereal part of the plant at each stage of development, through destructive sampling of tissue at 28, 49, 63, 77, 98 and 140 days after sowing. Concentrations of N, Ca, Mg and B in the bulb and foliar concentrations of N, Mg and Cu in the flowering season, directly influence the number of commercial shoots while the leaf-level contents of Ca, Mg

  18. Synthesis, crystal growth, optical, thermal, and mechanical properties of a nonlinear optical single crystal: ammonium sulfate hydrogen sulphamate (ASHS)

    Science.gov (United States)

    Sudhakar, K.; Nandhini, S.; Muniyappan, S.; Arumanayagam, T.; Vivek, P.; Murugakoothan, P.

    2018-04-01

    Ammonium sulfate hydrogen sulphamate (ASHS), an inorganic nonlinear optical crystal, was grown from the aqueous solution by slow evaporation solution growth technique. The single-crystal XRD confirms that the grown single crystal belongs to the orthorhombic system with the space group of Pna21. Powder XRD confirms the crystalline nature and the diffraction planes were indexed. Crystalline perfection of grown crystal was analysed by high-resolution X-ray diffraction rocking curve technique. UV-Vis-NIR studies revealed that ASHS crystal has optical transparency 65% and lower cut-off wavelength at 218 nm. The violet light emission of the crystal was identified by photoluminescence studies. The particle size-dependent second-harmonic generation efficiency for ASHS crystal was evaluated by Kurtz-Perry powder technique using Nd:YAG laser which established the existence of phase matching. Surface laser damage threshold value was evaluated using Nd:YAG laser. Optical homogeneity of the crystal was evaluated using modified channel spectrum method through birefringence study. Thermal analysis reveals that ASHS crystal is stable up to 213 °C. The mechanical behaviour of the ASHS crystal was analysed using Vickers microhardness study.

  19. Crystal growth and property characterization for PIN–PMN–PT ternary piezoelectric crystals

    Directory of Open Access Journals (Sweden)

    Jian Tian

    2014-01-01

    Full Text Available Binary piezoelectric crystal Pb(Mg1/3Nb2/3O3–PbTiO3 (PMN–PT has excellent dielectric and piezoelectric properties, which has led to the commercialization for medical ultrasound imaging. Recently, there is a growing demand for piezoelectric crystals with improved thermal and electrical properties. Ternary piezoelectric crystals Pb(In1/2Nb1/2O3–Pb(Mg1/3Nb2/3O3–PbTiO3 (PIN–PMN–PT have increased depoling temperature and coercive field than binary PMN–PT. To better understand the ternary crystal system and improve crystal properties, we systematically investigated crystal growth of PIN–PMN–PT with modified Bridgman method. Like PMN–PT, PIN–PMN–PT crystals have excellent piezoelectric properties (e.g., k33 ~ 0.87–0.92, d33 ~ 1000–2200 pm/V. Higher PIN content leads to ~40°C increase in depoling temperature and more than doubling of coercive field(~7.0 kV/cm. Such improvements are advantageous for applications where high temperature and/or high-drive are needed.

  20. Mesoscopic surface roughness of ice crystals pervasive across a wide range of ice crystal conditions

    Science.gov (United States)

    Magee, N. B.; Miller, A.; Amaral, M.; Cumiskey, A.

    2014-11-01

    Here we show high-magnification images of hexagonal ice crystals acquired by environmental scanning electron microscopy (ESEM). Most ice crystals were grown and sublimated in the water vapor environment of an FEI-Quanta-200 ESEM, but crystals grown in a laboratory diffusion chamber were also transferred intact and imaged via ESEM. All of these images display prominent mesoscopic topography including linear striations, ridges, islands, steps, peaks, pits, and crevasses; the roughness is not observed to be confined to prism facets. The observations represent the most highly magnified images of ice surfaces yet reported and expand the range of conditions in which rough surface features are known to be conspicuous. Microscale surface topography is seen to be ubiquitously present at temperatures ranging from -10 °C to -40 °C, in supersaturated and subsaturated conditions, on all crystal facets, and irrespective of substrate. Despite the constant presence of surface roughness, the patterns of roughness are observed to be dramatically different between growing and sublimating crystals, and transferred crystals also display qualitatively different patterns of roughness. Crystals are also demonstrated to sometimes exhibit inhibited growth in moderately supersaturated conditions following exposure to near-equilibrium conditions, a phenomenon interpreted as evidence of 2-D nucleation. New knowledge about the characteristics of these features could affect the fundamental understanding of ice surfaces and their physical parameterization in the context of satellite retrievals and cloud modeling. Links to supplemental videos of ice growth and sublimation are provided.

  1. Nonlinear and quantum optics with liquid crystals

    International Nuclear Information System (INIS)

    Lukishova, Svetlana G

    2014-01-01

    Thermotropic liquid crystals' usual application is display technology. This paper describes experiments on light interaction with pure and doped liquid crystals under for these materials unconventional incident light powers: (1) under high-power laser irradiation, and (2) at the single-photon level. In (1), I will outline several nonlinear optical effects under high-power, nanosecond laser irradiation which should be taken into account in the design of lasers with liquid crystal components and in fabrication of optical power limiters based on liquid crystals: (1.1) athermal helical pitch dilation and unwinding of cholesteric mirrors (both in free space and inside laser resonators); (1.2) some pitfalls in measurements of refractive nonlinearity using z-scan technique under two-photon or linear absorption of liquids; (1.3) the first observation of thermal lens effects in liquid crystals under several-nanosecond, low-pulse-repetition rate (2-10 Hz) laser irradiation in the presence of two-photon absorption; (1.4) feedback-free kaleidoscope of patterns (hexagons, stripes, etc.) in dye-doped liquid crystals. In (2), at the single-photon level, it will be shown that with a proper selection of liquid crystals and a single-emitter dopant spectral range, liquid crystal structures can be used to control emitted single photons (both polarization and count rate). The application of the latter research is absolutely secure quantum communication with polarization coding of information. In particular, in (2.1), definite handedness, circular polarized cholesteric microcavity resonance in quantum dot fluorescence is reported. In (2.2), definite linear polarization of single (antibunched) photons from single-dye-molecules in planar-aligned nematic host is discussed. In (2.3), some results on photon antibunching from NV-color center in nanodiamond in liquid crystal host and circularly polarized fluorescence of definite handedness from nanocrystals doped with trivalent ions of

  2. Growth and characterization of 2-methylquinolinium L-malate single crystal

    Science.gov (United States)

    Bharathi, M. Divya; Ahila, G.; Mohana, J.; Anbalagan, G.

    2017-05-01

    An organic nonlinear optical single crystal, 2-methylquinolinium L-malate (MLM) was grown from ethanol solvent using slow evaporation solution growth technique. The single crystal X-ray diffraction studies confirmed that the crystal belongs to the monoclinic system with the non-centrosymmetric space group P21. The crystal is transparent in the entire visible region. The second harmonic generation efficiency of the grown crystal has been obtained by the Kurtz-Perry powder technique. The laser damage threshold value 5.58 GW/cm2 indicates that this crystal can be used for high-power laser applications.

  3. Graded photonic crystals by optical interference holography

    Science.gov (United States)

    Han, Chunrui; Tam, Wing Yim

    2012-08-01

    We report on the fabrication of graded photonic crystals in dye doped dichromate gelatin emulsions using an optical interference holographic technique. The gradedness is achieved by imposing a gradient form factor in the interference intensity resulting from the absorption of the dye in the dichromate gelatin. Wider and deeper photonic bandgaps are observed for the dyed samples as compared to the un-dyed samples. Our method could open up a new direction in fabricating graded photonic crystals which cannot be achieved easily using other techniques.

  4. Imaging of protein crystals with two–photon microscopy†

    Science.gov (United States)

    Padayatti, Pius; Palczewska, Grazyna; Sun, Wenyu; Palczewski, Krzysztof; Salom, David

    2012-01-01

    Second–order non–linear optical imaging of chiral crystals (SONICC), that portrays second harmonic generation (SHG) by non–centrosymmetric crystals, is emerging as a powerful imaging technique for protein crystals in media opaque to visible light because of its high signal–to–noise ratio. Here we report the incorporation of both SONICC and two–photon excited fluorescence (TPEF) into one imaging system that allows visualization of crystals as small as ~10 μm in their longest dimension. Using this system, we then documented an inverse correlation between the level of symmetry in examined crystals and the intensity of their SHG. Moreover, because of blue-green TPEF exhibited by most tested protein crystals, we also could identify and image SHG–silent protein crystals. Our experimental data suggests that the TPEF in protein crystals is mainly caused by the oxidation of tryptophan residues. Additionally, we found that unspecific fluorescent dyes are able to bind to lysozyme crystals and enhance their detection by TPFE. We finally confirmed that the observed fluorescence was generated by a two-photon rather than a three-photon process. The capability for imaging small protein crystals in turbid or opaque media with non–damaging infrared light in a single system, makes the combination of SHG and intrinsic visible TPEF a powerful tool for non–destructive protein crystal identification and characterization during crystallization trials. PMID:22324807

  5. 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.

  6. Defect reduction in seeded aluminum nitride crystal growth

    Energy Technology Data Exchange (ETDEWEB)

    Bondokov, Robert T.; Morgan, Kenneth E.; Schowalter, Leo J.; Stack, Glen A.

    2017-04-18

    Bulk single crystal of aluminum nitride (AlN) having an areal planar defect density.ltoreq.100 cm.sup.-2. Methods for growing single crystal aluminum nitride include melting an aluminum foil to uniformly wet a foundation with a layer of aluminum, the foundation forming a portion of an AlN seed holder, for an AlN seed to be used for the AlN growth. The holder may consist essentially of a substantially impervious backing plate.

  7. Defect reduction in seeded aluminum nitride crystal growth

    Energy Technology Data Exchange (ETDEWEB)

    Bondokov, Robert T.; Morgan, Kenneth E.; Schowalter, Leo J.; Slack, Glen A.

    2017-06-06

    Bulk single crystal of aluminum nitride (AlN) having an areal planar defect density .ltoreq.100 cm.sup.-2. Methods for growing single crystal aluminum nitride include melting an aluminum foil to uniformly wet a foundation with a layer of aluminum, the foundation forming a portion of an AlN seed holder, for an AlN seed to be used for the AlN growth. The holder may consist essentially of a substantially impervious backing plate.

  8. Defect reduction in seeded aluminum nitride crystal growth

    Science.gov (United States)

    Bondokov, Robert T.; Schowalter, Leo J.; Morgan, Kenneth; Slack, Glen A; Rao, Shailaja P.; Gibb, Shawn Robert

    2017-09-26

    Bulk single crystal of aluminum nitride (AlN) having an areal planar defect density.ltoreq.100 cm.sup.-2. Methods for growing single crystal aluminum nitride include melting an aluminum foil to uniformly wet a foundation with a layer of aluminum, the foundation forming a portion of an AlN seed holder, for an AlN seed to be used for the AlN growth. The holder may consist essentially of a substantially impervious backing plate.

  9. Crystal growth and comparison of vibrational and thermal properties

    Indian Academy of Sciences (India)

    with the spectrum of urea thiourea mercury chloride (UTHC) (red) isolated by grow- ing a crystal using urea (u), thiourea (tu) and HgCl2, in 1 : 1 : 1 mole ratio showing that both are one and the same. is no mention of growth of any doped crystals other than the UTHC and UTHS. Fur- ther, it is unfortunate that the exact nature ...

  10. Studies of laser crystal growth. 1. Production of crystal growth furnaces and operating results

    International Nuclear Information System (INIS)

    Sugiyama, Akira; Sasuga, Tsuneo; Arisawa, Takashi; Takuma, Hiroshi; Anzai, Yutaka; Katsurayama, Masamichi; Yamazaki, Takafumi; Yamagishi, Kiyoshi.

    1997-10-01

    Table top short pulse Peta-watt laser system is the most promising light source to drive studying high energy field physics in advance photon research. To achieve high efficiency laser oscillation in stable condition, it is required to pull out the best performance from laser crystals as the gain medium. Therefore, we have conducted cooperative investigation with Mitsui Mining and Smelting Co., LTD. to create large ideal laser crystals by improved growth methods which solve several problems in usual growth techniques. This report describes specifications, results of operation, and improvements in two different types of growth furnaces which make homogeneous doped concentration along growth direction of Nd:YAG laser crystal and large fluoride laser crystals with a wide band gap, respectively. It also describes the first four results of crystals such as YAG, Nd:YAG, YLF, and LBO grown by these furnaces. (author)

  11. Fast response liquid crystal devices

    Science.gov (United States)

    Wu, Yung-Hsun

    called axially-symmetric sheared polymer network liquid crystals (AS-SPNLC) and use it as LC devices. Through analyzing the structure of this axially-symmetric SPNLC, we construct a 3-D model to explain the observed phenomena. An axially-symmetric sheared polymer network liquid crystal has several attractive features: (1) it is polarization independent, (2) it has gradient phase change, and (3) its response time is fast. It can be used for polarization converter and divergent LC lens. In addition, a new method for simultaneously measuring the phase retardation and optic axis of a compensation film is demonstrated using an axially-symmetric sheared polymer network liquid crystal. By overlaying a tested compensation film with a calibrated SPNLC cell between crossed polarizers, the optic axis and phase retardation value of the compensation film can be determined. This simple technique can be used for simultaneously measuring the optic axis and phase retardations of both A- and C-plates. These compensation films have been used extensively in wide-view LCD industry. Therefore, this method will make an important impact to the LCD industry.

  12. New Crystal-Growth Methods for Producing Lattice-Matched Substrates for High-Temperature Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Boatner, L.A.

    2008-06-24

    This effort addressed the technical problem of identifying and growing, on a commercial scale, suitable single-crystal substrates for the subsequent deposition of epitaxial thin films of high temperature semiconductors such as GaN/AlN. The lack of suitable lattice-matched substrate materials was one of the major problem areas in the development of semiconducting devices for use at elevated temperatures as well as practical opto-electronic devices based on Al- and GaN technology. Such lattice-matched substrates are necessary in order to reduce or eliminate high concentrations of defects and dislocations in GaN/AlN and related epitaxial thin films. This effort concentrated, in particular, on the growth of single crystals of ZnO for substrate applications and it built on previous ORNL experience in the chemical vapor transport growth of large single crystals of zinc oxide. This combined expertise in the substrate growth area was further complemented by the ability of G. Eres and his collaborators to deposit thin films of GaN on the subject substrates and the overall ORNL capability for characterizing the quality of such films. The research effort consisted of research on the growth of two candidate substrate materials in conjunction with concurrent research on the growth and characterization of GaN films, i.e. the effort combined bulk crystal growth capabilities in the area of substrate production at both ORNL and the industrial partner, Commercial Crystal Growth Laboratories (CCL), Naples, Florida, with the novel thin-film deposition techniques previously developed in the ORNL SSD.

  13. Microsatellite Primers for Fungus-Growing Ants

    DEFF Research Database (Denmark)

    Villesen Fredsted, Palle; Gertsch, Pia J.; Boomsma, Jacobus Jan (Koos)

    2002-01-01

    We isolated five polymorphic microsatellite loci from a library of two thousand recombinant clones of two fungus-growing ant species, Cyphomyrmex longiscapus and Trachymyrmex cf. zeteki. Amplification and heterozygosity were tested in five species of higher attine ants using both the newly...... developed primers and earlier published primers that were developed for fungus-growing ants. A total of 20 variable microsatellite loci, developed for six different species of fungus-growing ants, are now available for studying the population genetics and colony kin-structure of these ants....

  14. Microsatellite primers for fungus-growing ants

    DEFF Research Database (Denmark)

    Villesen, Palle; Gertsch, P J; Boomsma, JJ

    2002-01-01

    We isolated five polymorphic microsatellite loci from a library of two thousand recombinant clones of two fungus-growing ant species, Cyphomyrmex longiscapus and Trachymyrmex cf. zeteki. Amplification and heterozygosity were tested in five species of higher attine ants using both the newly...... developed primers and earlier published primers that were developed for fungus-growing ants. A total of 20 variable microsatellite loci, developed for six different species of fungus-growing ants, are now available for studying the population genetics and colony kin-structure of these ants....

  15. Magnetic, electric and optic properties of liquid crystals

    International Nuclear Information System (INIS)

    Florea, St.C.

    1980-01-01

    We study the nematic liquid crystals of thermotrop type. We also studied the crystals whose mesomorphism occured both at temperature increasing and decreasing and during the supercooling phase (monotrope). Investigation results performed by us have had in view the following: clearing up and experimental support of a new mechanism of nuclear relaxation in liquid crystals, proposed by author; usage of experimental techniques and methods for to characterize and test some mesomorph media used in very important applications, such as color TV. (author)

  16. Crystallization and crystal properties of squid rhodopsin

    International Nuclear Information System (INIS)

    Murakami, Midori; Kitahara, Rei; Gotoh, Toshiaki; Kouyama, Tsutomu

    2007-01-01

    Truncated rhodopsin from the retina of the squid Todarodes pacificus was extracted and crystallized by the sitting-drop vapour-diffusion method. Hexagonal crystals grown in the presence of octylglucoside and ammonium sulfate diffracted to 2.8 Å resolution. Rhodopsin, a photoreceptor membrane protein in the retina, is a prototypical member of the G-protein-coupled receptor family. In this study, rhodopsin from the retina of the squid Todarodes pacificus was treated with V8 protease to remove the C-terminal extension. Truncated rhodopsin was selectively extracted from the microvillar membranes using alkyl glucoside in the presence of zinc ions and was then crystallized by the sitting-drop vapour-diffusion method. Of the various crystals obtained, hexagonal crystals grown in the presence of octylglucoside and ammonium sulfate diffracted to 2.8 Å resolution. The diffraction data suggested that the crystal belongs to space group P6 2 , with unit-cell parameters a = b = 122.1, c = 158.6 Å. Preliminary crystallographic analysis, together with linear dichroism results, suggested that the rhodopsin dimers are packed in such a manner that their transmembrane helices are aligned nearly parallel to the c axis

  17. Adaptive and Parallel Computational Techniques in Materials Science

    National Research Council Canada - National Science Library

    Flaherty, Joseph

    1998-01-01

    This Augmentation Award for Science and Engineering Research Training (AASERT) supported research students to work 0 adaptive and parallel computational techniques associated with crystal growth processing...

  18. Solid microparticles in nematic liquid crystals

    Science.gov (United States)

    Muševič, Igor

    A brief historic overview of colloidal experiments in the 1990's is given in the introduction. These experiments have later inspired research on nematic colloids, after the technique of laser tweezers manipulation of particles was introduced to this field. Basic topological properties of colloidal inclusions in the nematic liquid crystals are discussed and the nematic-mediated forces between dipolar and quadrupolar colloidal particles in bulk nematic are explained. Structural and topological properties of 2D and 3D colloidal crystals and superstructures made of colloidal particles of different size and symmetry in bulk nematic liquid crystal are described. Laser-tweezer manipulation and rewiring of topological defect loops around colloidal particles is introduced. This results in the colloidal entanglement, as well as knotting and linking of defect loops of the order parameter field. Shape and size-dependent colloidal interactions in the nematic liquid crystals are reviewed. The chapter concludes with the discussion of bulk chiral nematic and blue phase colloids.

  19. Trace element distribution in geological crystals

    Energy Technology Data Exchange (ETDEWEB)

    Den Besten, J.L.; Jamieson, D.N.; Weiser, P.S. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1996-12-31

    Channelling is a useful microprobe technique for determining the structure of crystals, but until now has not been performed on geological crystals. The composition has been investigated rather than the structure, which can further explain the origin of the crystal and provide useful information on the substitutionality of trace elements. This may then lead to applications of extraction of valuable metals and semiconductor electronics. Natural crystals of pyrite, FeS{sub 2}, which contains a substantial concentration of gold were channeled and examined to identify the channel axis orientation. Rutherford Backscattering (RBS) and Particle Induced X-Ray Emission (PIXE) spectra using MeV ions were obtained in the experiment to provide a comparison of lattice and non-lattice trace elements. 3 figs.

  20. Mobility improvement by detached solidification of CZT crystals

    Science.gov (United States)

    Gamal, G. A.; Abou Zied, M.; Ebnalwaled, A. A.

    2007-06-01

    The mobility of undoped CdZnTe (CZT) crystals grown by vertical Bridgman method is improved by growing crystals without wall contact. Among the different factors playing an important role for appearance of detached growth, we have chosen the freezing rate as an effective factor for investigation with other factors were held constant. After growing a set of samples we have measured the dislocation densities for the grown samples by Warren-Averbach method. Unique results were obtained when we compared the dislocation densities and mobility, together with the freezing rate. This work and the included relations are published for the first time.

  1. Mobility improvement by detached solidification of CZT crystals

    Energy Technology Data Exchange (ETDEWEB)

    Gamal, G.A. [Physics Department, Faculty of Science, South Valley University, Qena 83523 (Egypt); Abou Zied, M. [Physics Department, Faculty of Science, South Valley University, Qena 83523 (Egypt); Ebnalwaled, A.A. [Physics Department, Faculty of Science, South Valley University, Qena 83523 (Egypt)]. E-mail: Kh_ebnalwaled@yahoo.com

    2007-06-15

    The mobility of undoped CdZnTe (CZT) crystals grown by vertical Bridgman method is improved by growing crystals without wall contact. Among the different factors playing an important role for appearance of detached growth, we have chosen the freezing rate as an effective factor for investigation with other factors were held constant. After growing a set of samples we have measured the dislocation densities for the grown samples by Warren-Averbach method. Unique results were obtained when we compared the dislocation densities and mobility, together with the freezing rate. This work and the included relations are published for the first time.

  2. Morphological identification of not growing bacteria for neutron radiography

    International Nuclear Information System (INIS)

    Lopes, J.D.R.; Crispim, V.R.; Pessolani, M.C.V.

    2008-01-01

    The technological development associate the new discoveries in the genetic field, has contributed for an improvement in the diagnosis of determined illnesses, however the laboratories analysis nor always are carried through in desired the minimum time and precision, beyond not being optimized the financial resources. The result of these controversies can lead the loss of possibilities of overlife of the patients, taking them, also to the death. At present time, exist an expensive equipment capable to identify fastly a commons bacteria. However, to achieve reliable diagnostics, microorganisms have to grow in appropriate culture media before identification, what sometimes can take a great amount of time, making it difficult the diagnosis. Some of them, also, are not growing in artificial nutrients, being possible only its diagnosis after an inoculation carried through in laboratory guinea pigs, as in the case of the Mycobacterium leprae. Neutron radiography has been used for several years as a non-destructive technique with several applications. Giving credit itself the potentiality of this technique for the faster identification of bacteria in comparison with the conventional microbiological techniques, because there's no need for the overnight cultures. In this work was decided to proceed to the evaluation of the technique and the determination of the involved parameters. The work had demonstrated that the method can come to be promising, as a method auxiliary to already the existing ones, it is intended to give to continuity the research concentrating itself in the evaluation of the method for application in hemocultures and administer it in the diagnosis of bacteria that not growing in artificial ways, such as the Mycobacterium leprae. (author)

  3. Growing Languages with Metamorphic Syntax Macros

    DEFF Research Database (Denmark)

    Brabrand, Claus; Schwartzbach, Michael Ignatieff

    2002-01-01

    "From now on, a main goal in designing a language should be to plan for growth." Guy Steele: Growing a Language, OOPSLA '98 invited talk.We present our experiences with a syntax macro language which we claim forms a general abstraction mechanism for growing (domain-specific) extensions of program......"From now on, a main goal in designing a language should be to plan for growth." Guy Steele: Growing a Language, OOPSLA '98 invited talk.We present our experiences with a syntax macro language which we claim forms a general abstraction mechanism for growing (domain-specific) extensions...... of programming languages. Our syntax macro language is designed to guarantee type safety and termination.A concept of metamorphisms allows the arguments of a macro to be inductively defined in a meta level grammar and morphed into the host language. We also show how the metamorphisms can be made to operate...

  4. Investigation on crystalline perfection, mechanical, piezoelectric and ferroelectric properties of L-tartaric acid single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Murugan, G. Senthil, E-mail: nanosen@gmail.com; Ramasamy, P., E-mail: nanosen@gmail.com [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam, Tamilnadu - 603110 (India)

    2014-04-24

    Polar organic nonlinear optical material, L-tartaric acid single crystals have been grown from slow evaporation solution growth technique. Single crystal X-ray diffraction study indicates that the grown crystal crystallized in monoclinic system with space group P2{sub 1}. Crystalline perfection of the crystal has been evaluated by high resolution X-ray diffraction technique and it reveals that the crystal quality is good and free from structural grain boundaries. Mechanical stability of the crystal has been analyzed by Vickers microhardness measurement and it exhibits reverse indentation size effect. Piezoelectric d{sub 33} co-efficient for the crystal has been examined and its value is 47 pC/N. The ferroelectric behaviour of the crystal was analyzed by polarization-electric field hysteresis loop measurement.

  5. Growing America's Energy Future

    Energy Technology Data Exchange (ETDEWEB)

    None

    2016-06-01

    The emerging U.S. bioenergy industry provides a secure and growing supply of transportation fuels, biopower, and bioproducts produced from a range of abundant, renewable biomass resources. Bioenergy can help ensure a secure, sustainable, and economically sound future by reducing U.S. dependence on foreign oil, developing domestic clean energy sources, and generating domestic green jobs. Bioenergy can also help address growing concerns about climate change by reducing greenhouse gas emissions to create a healthier environment for current and future generations.

  6. Crystal growth and characterization of a semiorganic nonlinear optical single crystal of gamma glycine

    International Nuclear Information System (INIS)

    Prakash, J. Thomas Joseph; Kumararaman, S.

    2008-01-01

    Gamma glycine has been successfully synthesized by taking glycine and potassium chloride and single crystals have been grown by solvent evaporation method for the first time. The grown single crystals have been analyzed with XRD, Fourier transform infrared (FTIR), and thermo gravimetric and differential thermal analyses (TG/DTA) measurements. Its mechanical behavior has been assessed by Vickers microhardness measurements. Its nonlinear optical property has been tested by Kurtz powder technique. Its optical behavior was examined by UV-vis., and found that the crystal is transparent in the region between 240 and 1200 nm. Hence, it may be very much useful for the second harmonic generation (SHG) applications

  7. Effect of crucible and crystal rotations on the convexity and the thermal stress in large size sapphire crystals during Czochralski growth

    Science.gov (United States)

    Nguyen, Tran Phu; Hsieh, Yao-Te; Chen, Jyh-Chen; Hu, Chieh; Nguyen, Huy Bich

    2017-06-01

    In this study, the effect of the temperature and flow fields generated by the rotation of the crucible and the crystal on the convexity of a c-axis, large-diameter sapphire crystal during the Czochralski growth process is investigated numerically. The thermal stress distributions in different sizes of crystal are also considered. The computational results show that the convexity and the thermal stress of the crystal are strongly dependent on the crucible and crystal rotation rates. The counter rotation between the crucible and the crystal results in a flatter crystal-melt interface, compared to the case of no crucible rotation or crystal rotation. Maximum thermal stress occurs at the highest curvature of the crystal-melt interface which appears near the center of the growing crystal, and the value is directly proportional to the crystal's size. Moreover, there is a significant decrease in the von Mises stress for the crystal-melt interface with lower convexity due to a reduction in the temperature gradient in the radial direction along the interface. As the crystal length gets larger, the maximum von Mises stress rapidly reduces.

  8. Adaptive temperature profile control of a multizone crystal growth furnace

    Science.gov (United States)

    Batur, C.; Sharpless, R. B.; Duval, W. M. B.; Rosenthal, B. N.

    1991-01-01

    An intelligent measurement system is described which is used to assess the shape of a crystal while it is growing inside a multizone transparent furnace. A color video imaging system observes the crystal in real time, and determines the position and the shape of the interface. This information is used to evaluate the crystal growth rate, and to analyze the effects of translational velocity and temperature profiles on the shape of the interface. Creation of this knowledge base is the first step to incorporate image processing into furnace control.

  9. Pixel size and pitch measurements of liquid crystal spatial light ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 65; Issue 2. Pixel size and pitch ... Liquid crystal displays; spatial light modulator; optical diffraction. Abstract. We present a simple technique for the determination of pixel size and pitch of liquid crystal (LC) based spatial light modulator (SLM). The proposed method is ...

  10. Understanding Nickel Thin Film crystallization using X-Ray ...

    African Journals Online (AJOL)

    MICHAEL

    Being a novel technique of thin film deposition, demonstrated applications are increasingly developed. Some already feasible usages include magnetic media high density information storage. (Hsieh et al., 1997), liquid crystal display technology. (Robbie et al., 1999), photonic crystal (Kennedy et al., 2003), optical rotators, ...

  11. Zinc (tris) thiourea sulphate (ZTS): A single crystal neutron diffraction ...

    Indian Academy of Sciences (India)

    near IR laser radiations. In this study, the crystal structure of ZTS has been ob- tained in detail by single crystal neutron diffraction technique. Using the structural parameters and an existing formalism [1] based on the theory of bond polarizability, the contributions from each of the structural groups in the unit cell to the total.

  12. Detection of anomalies in NLO sulphamic acid single crystals by ...

    Indian Academy of Sciences (India)

    The ultrasonic pulse echo overlap technique (PEO) has been used to measure the velocities of 10 MHz acoustic waves in sulphamic acid single crystals in the range of 300–400 K. This study evaluated all the elastic stiffnessconstants, compliance constants and Poisson's ratios of the crystal. The temperature variations of the ...

  13. On the growth of calcium tartrate tetrahydrate single crystals

    Indian Academy of Sciences (India)

    Unknown

    menon, especially those involved in the gel technique. With an aim of controlling nucleation and improving the size, in the present study, we have grown pure calcium tartrate tetrahydrate single crystals using calcium formate mixed with formic acid as the supernatant solution. The grown crystals have been characterized by ...

  14. Single crystal growth of europium and ytterbium based intermetallic ...

    Indian Academy of Sciences (India)

    Abstract. This article covers the use of indium as a potential metal solvent for the crystal growth of europium and ytterbium-based intermetallic compounds. A brief view about the advantage of metal flux technique and the use of indium as reactive and non-reactive flux are outlined. Large single crystals of EuGe2, EuCoGe3.

  15. Mathematical aspects of Rietveld refinement and crystal structure ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. The core mathematics, goodness-of-fit parameters of Rietveld refinement technique is introduced for structural analysis of crystalline materials not available as single crystals. X-ray diffraction (XRD) pat- terns of PbTiO3 compound prepared by following solid-state route, suggests it to be in single crystal form. All.

  16. Electrically modulated transparent liquid crystal-optical grating projection

    DEFF Research Database (Denmark)

    Buss, Thomas; Smith, Cameron; Kristensen, Anders

    2013-01-01

    A transparent, fully integrated electrically modulated projection technique is presented based on light guiding through a thin liquid crystal layer covering sub-wavelength gratings. The reported device operates at 10 V with response times of 4.5 ms. Analysis of the liquid crystal alignment shows...

  17. Vertical gradient freeze of 4 inch Ge crystals in a heater-magnet module

    Science.gov (United States)

    Frank-Rotsch, Ch.; Rudolph, P.

    2009-04-01

    For the first time 4-in. Ge single crystals were grown using the vertical gradient freeze technique (VGF) in a traveling magnetic field (TMF) generated in a heater-magnet module (HMM). The HMM was placed closely around the growth container inside the chamber of the industrial Bridgman equipment "Kronos". The HMM generates heat and a TMF together. It has a coil-shaped design and replaces the standard meander-type heater. Direct current (DC) for heat production and out-of-phase-accelerated currents (AC) for TMF generation were simultaneously delivered to three equally spaced coil segments connected by star-type wiring. In order to achieve a nearly flat and slightly convex growing interface the AC amplitude, frequency and phase shift have been optimized numerically by using the 3D CrysMAS code and validated by striation analysis on as-grown crystals. Low-field frequencies in the range f=20-50 Hz proved to be of most suitable condition. TMF programming is required to obtain constant interface morphology over the whole growth run. First Ge single crystals grown under nearly optimal conditions show reduced macro- and micro-inhomogeneities, relatively low dislocation density of (3-10)×10 2 cm -2, and high carrier mobility of μp=2800 cm 2 V -1 s -1.

  18. 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.

  19. Temperature-mediated polymorphism in molecular crystals: The impact on crystal packing and charge transport

    KAUST Repository

    Stevens, Loah A.

    2015-01-13

    We report a novel synthesis to ultra high purity 7,14-bis((trimethylsilyl)ethynyl)dibenzo[b,def]-chrysene (TMS-DBC) and the use of this material in the growth of single crystals by solution and vapor deposition techniques. We observe that the substrate temperature has a dramatic impact on the crystal growth, producing two distinct polymorphs of TMS-DBC; low temperature (LT) fine red needles and high temperature (HT) large yellow platelets. Single crystal X-ray crystallography confirms packing structures where the LT crystals form a 1D slipped-stack structure, while the HT crystals adopt a 2D brickwork motif. These polymorphs also represent a rare example where both are extremely stable and do not interconvert to the other crystal structure upon solvent or thermal annealing. Single crystal organic field-effect transistors of the LT and HT crystals show that the HT 2D brickwork motif produces hole mobilities as high as 2.1 cm2 V-1 s-1, while the mobility of the 1D structure is significantly lower, at 0.028 cm2 V-1 s-1. Electronic-structure calculations indicate that the superior charge transport in the brickwork polymorph in comparison to the slipped-stack polymorph is due to the presence of an increased dimensionality of the charge migration pathways.

  20. Synthesis, crystal structure, physicochemical properties of hydrogen bonded supramolecular assembly of N,N-diethylanilinium-3, 5-dinitrosalicylate crystal

    Science.gov (United States)

    Rajkumar, M.; Chandramohan, A.

    2017-12-01

    An organic salt, N,N-diethylanilinium 3,5-dinitrosalicylate was synthesized and single crystals grown by employing the slow solvent evaporation solution growth technique in methanol-acetone (1:1) mixture. The electronic transitions of the salt crystal were studied by UV-Visible spectrum. The optical transmittance window and lower wavelength cut-off of grown crystal have been identified by UV-Vis-NIR studies. The FT-IR spectrum was recorded to confirm the presence of various functional groups in the grown crystal. 1H and 13C NMR spectrum were recorded to establish the molecular structure of the title crystal. Single crystal X-ray diffraction data indicated that the crystal belongs to monoclinic crystal system with P21/n space group. The thermal stability of the crystal was established by TG/DTA studies. The mechanical properties of the grown crystal were studied by Vickers' microhardness technique. The dielectric studies indicated that the dielectric constant and dielectric loss decrease exponentially with frequency at different temperatures.

  1. Image segmentation by iterative parallel region growing and splitting

    Science.gov (United States)

    Tilton, James C.

    1989-01-01

    The spatially constrained clustering (SCC) iterative parallel region-growing technique is applied to image analysis. The SCC algorithm is implemented on the massively parallel processor at NASA Goddard. Most previous region-growing approaches have the drawback that the segmentation produced depends on the order in which portions of the image are processed. The ideal solution to this problem (merging only the single most similar pair of spatially adjacent regions in the image in each iteration) becomes impractical except for very small images, even on a massively parallel computer. The SCC algorithm overcomes these problems by performing, in parallel, the best merge within each of a set of local, possibly overlapping, subimages. A region-splitting stage is also incorporated into the algorithm, but experiments show that region splitting generally does not improve segmentation results. The SCC algorithm has been tested on various imagery data, and test results for a Landsat TM image are summarized.

  2. Characterising laser beams with liquid crystal displays

    Science.gov (United States)

    Dudley, Angela; Naidoo, Darryl; Forbes, Andrew

    2016-02-01

    We show how one can determine the various properties of light, from the modal content of laser beams to decoding the information stored in optical fields carrying orbital angular momentum, by performing a modal decomposition. Although the modal decomposition of light has been known for a long time, applied mostly to pattern recognition, we illustrate how this technique can be implemented with the use of liquid-crystal displays. We show experimentally how liquid crystal displays can be used to infer the intensity, phase, wavefront, Poynting vector, and orbital angular momentum density of unknown optical fields. This measurement technique makes use of a single spatial light modulator (liquid crystal display), a Fourier transforming lens and detector (CCD or photo-diode). Such a diagnostic tool is extremely relevant to the real-time analysis of solid-state and fibre laser systems as well as mode division multiplexing as an emerging technology in optical communication.

  3. Domains in Ferroic Crystals and Thin Films

    CERN Document Server

    Tagantsev, Alexander K; Fousek, Jan

    2010-01-01

    Domains in Ferroic Crystals and Thin Films presents experimental findings and theoretical understanding of ferroic (non-magnetic) domains developed during the past 60 years. It addresses the situation by looking specifically at bulk crystals and thin films, with a particular focus on recently-developed microelectronic applications and methods for observation of domains with techniques such as scanning force microscopy, polarized light microscopy, scanning optical microscopy, electron microscopy, and surface decorating techniques. Domains in Ferroic Crystals and Thin Films covers a large area of material properties and effects connected with static and dynamic properties of domains, which are extremely relevant to materials referred to as ferroics. In most solid state physics books, one large group of ferroics is customarily covered: those in which magnetic properties play a dominant role. Numerous books are specifically devoted to magnetic ferroics and cover a wide spectrum of magnetic domain phenomena. In co...

  4. Prospects for the synthesis of large single-crystal diamonds

    International Nuclear Information System (INIS)

    Khmelnitskiy, R A

    2015-01-01

    The unique properties of diamond have stimulated the study of and search for its applications in many fields, including optics, optoelectronics, electronics, biology, and electrochemistry. Whereas chemical vapor deposition allows the growth of polycrystalline diamond plates more than 200 mm in diameter, most current diamond application technologies require large-size (25 mm and more) single-crystal diamond substrates or films suitable for the photolithography process. This is quite a challenge, because the largest diamond crystals currently available are 10 mm or less in size. This review examines three promising approaches to fabricating large-size diamond single crystals: growing large-size single crystals, the deposition of heteroepitaxial diamond films on single-crystal substrates, and the preparation of composite diamond substrates. (reviews of topical problems)

  5. 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.

  6. Homogeneous SiGe crystal growth in microgravity by the travelling liquidus-zone method

    International Nuclear Information System (INIS)

    Kinoshita, K; Arai, Y; Inatomi, Y; Sakata, K; Takayanagi, M; Yoda, S; Miyata, H; Tanaka, R; Sone, T; Yoshikawa, J; Kihara, T; Shibayama, H; Kubota, Y; Shimaoka, T; Warashina, Y

    2011-01-01

    Homogeneous SiGe crystal growth experiments will be performed on board the ISS 'Kibo' using a gradient heating furnace (GHF). A new crystal growth method invented for growing homogeneous mixed crystals named 'travelling liquidus-zone (TLZ) method' is evaluated by the growth of Si 0.5 Ge 0.5 crystals in space. We have already succeeded in growing homogeneous 2mm diameter Si 0.5 Ge 0.5 crystals on the ground but large diameter homogeneous crystals are difficult to be grown due to convection in a melt. In microgravity, larger diameter crystals can be grown with suppressing convection. Radial concentration profiles as well as axial profiles in microgravity grown crystals will be measured and will be compared with our two-dimensional TLZ growth model equation and compositional variation is analyzed. Results are beneficial for growing large diameter mixed crystals by the TLZ method on the ground. Here, we report on the principle of the TLZ method for homogeneous crystal growth, results of preparatory experiments on the ground and plan for microgravity experiments.

  7. Identifying, studying and making good use of macromolecular crystals

    Energy Technology Data Exchange (ETDEWEB)

    Calero, Guillermo [University of Pittsburgh Medical School, Pittsburgh, PA 15261 (United States); Cohen, Aina E. [SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025 (United States); Luft, Joseph R. [Hauptman–Woodward Medical Research Institute, 700 Ellicott Street, Buffalo, NY 14203 (United States); State University of New York at Buffalo, 700 Ellicott Street, Buffalo, NY 14203 (United States); Newman, Janet [CSIRO Collaborative Crystallisation Centre, 343 Royal Parade, Parkville, Victoria 3052 (Australia); Snell, Edward H., E-mail: esnell@hwi.buffalo.edu [Hauptman–Woodward Medical Research Institute, 700 Ellicott Street, Buffalo, NY 14203 (United States); State University of New York at Buffalo, 700 Ellicott Street, Buffalo, NY 14203 (United States); University of Pittsburgh Medical School, Pittsburgh, PA 15261 (United States)

    2014-07-25

    As technology advances, the crystal volume that can be used to collect useful X-ray diffraction data decreases. The technologies available to detect and study growing crystals beyond the optical resolution limit and methods to successfully place the crystal into the X-ray beam are discussed. Structural biology has contributed tremendous knowledge to the understanding of life on the molecular scale. The Protein Data Bank, a depository of this structural knowledge, currently contains over 100 000 protein structures, with the majority stemming from X-ray crystallography. As the name might suggest, crystallography requires crystals. As detectors become more sensitive and X-ray sources more intense, the notion of a crystal is gradually changing from one large enough to embellish expensive jewellery to objects that have external dimensions of the order of the wavelength of visible light. Identifying these crystals is a prerequisite to their study. This paper discusses developments in identifying these crystals during crystallization screening and distinguishing them from other potential outcomes. The practical aspects of ensuring that once a crystal is identified it can then be positioned in the X-ray beam for data collection are also addressed.

  8. Raphide crystal structure in agave tequilana determined by x-ray originating from synchrotron radiation

    International Nuclear Information System (INIS)

    Tadokoro, Makoto; Ozawa, Yoshiki; Mitsumi, Minoru; Toriumi, Kohshiro; Ogura, Tetsuya

    2005-01-01

    The first single crystal structure of small natural raphides in an agave plant is completely determined using an intense X-ray originating from a synchrotron radiation. The SEM image shows that the tip of the crystal is approximately hundreds of nanometer in width sharply grow to stick to the tissue of herbivorous vermin. Furthermore, the crystal develops cracks that propagate at an inclination of approximately 45deg towards the direction of crystal growth such that the crystal easily splits into small pieces in the tissue. (author)

  9. 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.

  10. Single Crystal Surfaces

    Science.gov (United States)

    Aguilar-Santillan, Joaquin

    2014-06-01

    The present work studies (0001) Al2O3 and (111) Al2MgO4 wetting with pure molten Al by the sessile drop technique from 1073 K to 1473 K (800 °C to 1200 °C) under Ar at PO2 10-15 Pa. Al pure liquid wets a smooth and chemically homogeneous surface of an inert solid, the wetting driving force ( t, T) can be readily studied when surface solid roughness increases in the system. Both crystals planes (0001) Al2O3 and (111) Al2MgO4 have crystallographic surfaces with identical O-2 crystalline positions however considering Mg2+ content in Al2MgO4 structure may influence a reactive mode. Kinetic models results under similar experimental conditions show that Al wetting on (0001) Al2O3 is less reactive than (111) Al2MgO4, however at >1273 K (1000 °C) (0001) Al2O3 transformation occurs and a transition of wetting improves. The (111) Al2MgO4 and Al system promotes interface formations that slow its wetting process.

  11. Silicon Crystal Growth by the Electromagnetic Czochralski (EMCZ) Method

    Science.gov (United States)

    Watanabe, Masahito; Eguchi, Minoru; Hibiya, Taketoshi

    1999-01-01

    A new method for growing silicon crystals by using electromagnetic force to rotate the melt without crucible rotation has been developed. We call it electromagnetic Czochralski (EMCZ) growth. An electromagnetic force in the azimuthal direction is generated in the melt by the interaction between an electric current (I) through the melt in the radial direction and a vertical magnetic field (B). The rotation rate (ωm) of the silicon melt is continuously changed from 0 to over 105 rpm under I = 0 to 8 A and B = 0 to 0.1 T. Thirty-mm-diameter silicon single crystals free of dislocations could be grown under two conditions: I = 2.0 A and B = 0.05 T (ωm = 105 rpm); and I =0.2 A and B = 0.1 T (ωm = 15 rpm). The oxygen concentration in the crystals was 8 ×1017 atoms/cm3 for the high rotation rate and 1×1017 atoms/cm3 for the low rotation rate. The oxygen-concentration distributions in the radial direction in both crystals were more homogeneous than those in the crystals grown by conventional CZ and/or MCZ growth. This new crystal-growth method can be easily adopted for growing large-diameter silicon crystals.

  12. Ultra-large single crystals by abnormal grain growth.

    Science.gov (United States)

    Kusama, Tomoe; Omori, Toshihiro; Saito, Takashi; Kise, Sumio; Tanaka, Toyonobu; Araki, Yoshikazu; Kainuma, Ryosuke

    2017-08-25

    Producing a single crystal is expensive because of low mass productivity. Therefore, many metallic materials are being used in polycrystalline form, even though material properties are superior in a single crystal. Here we show that an extraordinarily large Cu-Al-Mn single crystal can be obtained by abnormal grain growth (AGG) induced by simple heat treatment with high mass productivity. In AGG, the sub-boundary energy introduced by cyclic heat treatment (CHT) is dominant in the driving pressure, and the grain boundary migration rate is accelerated by repeating the low-temperature CHT due to the increase of the sub-boundary energy. With such treatment, fabrication of single crystal bars 70 cm in length is achieved. This result ensures that the range of applications of shape memory alloys will spread beyond small-sized devices to large-scale components and may enable new applications of single crystals in other metallic and ceramics materials having similar microstructural features.Growing large single crystals cheaply and reliably for structural applications remains challenging. Here, the authors combine accelerated abnormal grain growth and cyclic heat treatments to grow a superelastic shape memory alloy single crystal to 70 cm.

  13. Growth and Characterization on PMN-PT-Based Single Crystals

    Directory of Open Access Journals (Sweden)

    Jian Tian

    2014-07-01

    Full Text Available Lead magnesium niobate—lead titanate (PMN-PT single crystals have been successfully commercialized in medical ultrasound imaging. The superior properties of PMN-PT crystals over the legacy piezoelectric ceramics lead zirconate titanate (PZT enabled ultrasound transducers with enhanced imaging (broad bandwidth and improved sensitivity. To obtain high quality and relatively low cost single crystals for commercial production, PMN-PT single crystals were grown with modified Bridgman method, by which crystals were grown directly from stoichiometric melt without flux. For ultrasound imaging application, [001] crystal growth is essential to provide uniform composition and property within a crystal plate, which is critical for transducer performance. In addition, improvement in crystal growth technique is under development with the goals of improving the composition homogeneity along crystal growth direction and reducing unit cost of crystals. In recent years, PIN-PMN-PT single crystals have been developed with higher de-poling temperature and coercive field to provide improved thermal and electrical stability for transducer application.

  14. Thermodynamics, molecular mobility and crystallization kinetics of amorphous griseofulvin.

    Science.gov (United States)

    Zhou, Deliang; Zhang, Geoff G Z; Law, Devalina; Grant, David J W; Schmitt, Eric A

    2008-01-01

    Griseofulvin is a small rigid molecule that shows relatively high molecular mobility and small configurational entropy in the amorphous phase and tends to readily crystallize from both rubbery and glassy states. This work examines the crystallization kinetics and mechanism of amorphous griseofulvin and the quantitative correlation between the rate of crystallization and molecular mobility above and below Tg. Amorphous griseofulvin was prepared by rapidly quenching the melt in liquid N2. The thermodynamics and dynamics of amorphous phase were then characterized using a combination of thermal analysis techniques. After characterization of the amorphous phase, crystallization kinetics above Tg were monitored by isothermal differential scanning calorimetry (DSC). Transformation curves for crystallization fit a second-order John-Mehl-Avrami (JMA) model. Crystallization kinetics below Tg were monitored by powder X-ray diffraction and fit to the second-order JMA model. Activation energies for crystallization were markedly different above and below Tg suggesting a change in mechanism. In both cases molecular mobility appeared to be partially involved in the rate-limiting step for crystallization, but the extent of correlation between the rate of crystallization and molecular mobility was different above and below Tg. A lower extent of correlation below Tg was observed which does not appear to be explained by the molecular mobility alone and the diminishing activation energy for crystallization suggests a change in the mechanism of crystallization.

  15. 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...

  16. 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.

  17. 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...

  18. Carbon nanotubes as liquid crystals.

    Science.gov (United States)

    Zhang, Shanju; Kumar, Satish

    2008-09-01

    Carbon nanotubes are the best of known materials with a combination of excellent mechanical, electronic, and thermal properties. To fully exploit individual nanotube properties for various applications, the grand challenge is to fabricate macroscopic ordered nanotube assemblies. Liquid-crystalline behavior of the nanotubes provides a unique opportunity toward reaching this challenge. In this Review, the recent developments in this area are critically reviewed by discussing the strategies for fabricating liquid-crystalline phases, addressing the solution properties of liquid-crystalline suspensions, and exploiting the practical techniques of liquid-crystal routes to prepare macroscopic nanotube fibers and films.

  19. Crystallization of ornithine acetyltransferase from yeast by counter-diffusion and preliminary X-ray study

    International Nuclear Information System (INIS)

    Maes, Dominique; Crabeel, Marjolaine; Van de Weerdt, Cécile; Martial, Joseph; Peeters, Eveline; Charlier, Daniël; Decanniere, Klaas; Vanhee, Celine; Wyns, Lode; Zegers, Ingrid

    2006-01-01

    A study on the crystallization of ornithine acetyltransferase from yeast, catalysing the fifth step in microbial arginine synthesis, is presented. The use of the counter-diffusion technique removes the disorder present in one dimension in crystals grown by either batch or hanging-drop techniques. A study is presented on the crystallization of ornithine acetyltransferase from yeast, which catalyzes the fifth step in microbial arginine synthesis. The use of the counter-diffusion technique removes the disorder present in one dimension in crystals grown by either the batch or hanging-drop techniques. This makes the difference between useless crystals and crystals that allow successful determination of the structure of the protein. The crystals belong to space group P4, with unit-cell parameters a = b = 66.98, c = 427.09 Å, and a data set was collected to 2.76 Å

  20. Crystallization of ornithine acetyltransferase from yeast by counter-diffusion and preliminary X-ray study

    Energy Technology Data Exchange (ETDEWEB)

    Maes, Dominique, E-mail: dominique.maes@vub.ac.be; Crabeel, Marjolaine [Laboratorium voor Ultrastructuur, Vrije Universiteit Brussel (VUB) and Vlaams Interuniversitair Instituut voor Biotechnologie (VIB), Pleinlaan 2, B-1050 Brussels (Belgium); Van de Weerdt, Cécile; Martial, Joseph [Laboratoire de Biologie Moléculaire et de Génie Génétique, Université de Liège, Allée de la Chimie 3, B-4000 Liège (Belgium); Peeters, Eveline; Charlier, Daniël [Erfelijkheidsleer en Microbiologie, Vrije Universiteit Brussel (VUB), Pleinlaan 2, B-1050 Brussels (Belgium); Decanniere, Klaas; Vanhee, Celine; Wyns, Lode; Zegers, Ingrid [Laboratorium voor Ultrastructuur, Vrije Universiteit Brussel (VUB) and Vlaams Interuniversitair Instituut voor Biotechnologie (VIB), Pleinlaan 2, B-1050 Brussels (Belgium)

    2006-12-01

    A study on the crystallization of ornithine acetyltransferase from yeast, catalysing the fifth step in microbial arginine synthesis, is presented. The use of the counter-diffusion technique removes the disorder present in one dimension in crystals grown by either batch or hanging-drop techniques. A study is presented on the crystallization of ornithine acetyltransferase from yeast, which catalyzes the fifth step in microbial arginine synthesis. The use of the counter-diffusion technique removes the disorder present in one dimension in crystals grown by either the batch or hanging-drop techniques. This makes the difference between useless crystals and crystals that allow successful determination of the structure of the protein. The crystals belong to space group P4, with unit-cell parameters a = b = 66.98, c = 427.09 Å, and a data set was collected to 2.76 Å.

  1. Experimental techniques; Techniques experimentales

    Energy Technology Data Exchange (ETDEWEB)

    Roussel-Chomaz, P. [GANIL CNRS/IN2P3, CEA/DSM, 14 - Caen (France)

    2007-07-01

    This lecture presents the experimental techniques, developed in the last 10 or 15 years, in order to perform a new class of experiments with exotic nuclei, where the reactions induced by these nuclei allow to get information on their structure. A brief review of the secondary beams production methods will be given, with some examples of facilities in operation or under project. The important developments performed recently on cryogenic targets will be presented. The different detection systems will be reviewed, both the beam detectors before the targets, and the many kind of detectors necessary to detect all outgoing particles after the reaction: magnetic spectrometer for the heavy fragment, detection systems for the target recoil nucleus, {gamma} detectors. Finally, several typical examples of experiments will be detailed, in order to illustrate the use of each detector either alone, or in coincidence with others. (author)

  2. Atomic crystals resistive switching memory

    International Nuclear Information System (INIS)

    Liu Chunsen; Zhang David Wei; Zhou Peng

    2017-01-01

    Facing the growing data storage and computing demands, a high accessing speed memory with low power and non-volatile character is urgently needed. Resistive access random memory with 4F 2 cell size, switching in sub-nanosecond, cycling endurances of over 10 12 cycles, and information retention exceeding 10 years, is considered as promising next-generation non-volatile memory. However, the energy per bit is still too high to compete against static random access memory and dynamic random access memory. The sneak leakage path and metal film sheet resistance issues hinder the further scaling down. The variation of resistance between different devices and even various cycles in the same device, hold resistive access random memory back from commercialization. The emerging of atomic crystals, possessing fine interface without dangling bonds in low dimension, can provide atomic level solutions for the obsessional issues. Moreover, the unique properties of atomic crystals also enable new type resistive switching memories, which provide a brand-new direction for the resistive access random memory. (topical reviews)

  3. 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

  4. Semiconductor monolayer assemblies with oriented crystal faces

    KAUST Repository

    Ma, Guijun

    2012-01-01

    Fabrication of two-dimensional monolayers of crystalline oxide and oxynitride particles was attempted on glass plate substrates. X-Ray diffraction patterns of the assemblies show only specific crystal facets, indicative of the uniform orientation of the particles on the substrate. The selectivity afforded by this immobilization technique enables the organization of randomly distributed polycrystalline powders in a controlled manner.

  5. Screening for templates that promote crystallization

    NARCIS (Netherlands)

    Urbanus, J.; Roelands, C.P.M.; Horst, J.H. ter; Verdoes, D.; Jansens, P.J.

    2008-01-01

    In Situ Product Recovery (ISPR) applied in fermentation processes leads to improved yield and productivity of these processes. In principle, ISPR can be achieved using Template Induced Crystallization (TIC), which is one possible ISPR technique. With TIC, templates are added to the solution as a

  6. Supramolecular liquid crystal displays : construction and applications

    NARCIS (Netherlands)

    Hoogboom, Joannes Theodorus Valentinus

    2004-01-01

    This thesis describes chemical methodologies, which can be ued to construct alignment layers for liquid crystal display purposes in a non-clean room environment, by making use of supramolecular chemistry. These techniques are subsequently used to attain control over LCD-properties, both pre- and

  7. Synthetic thermoelectric materials comprising phononic crystals

    Science.gov (United States)

    El-Kady, Ihab F; Olsson, Roy H; Hopkins, Patrick; Reinke, Charles; Kim, Bongsang

    2013-08-13

    Synthetic thermoelectric materials comprising phononic crystals can simultaneously have a large Seebeck coefficient, high electrical conductivity, and low thermal conductivity. Such synthetic thermoelectric materials can enable improved thermoelectric devices, such as thermoelectric generators and coolers, with improved performance. Such synthetic thermoelectric materials and devices can be fabricated using techniques that are compatible with standard microelectronics.

  8. Improved procedures for separating crystals from the melt

    NARCIS (Netherlands)

    Verdoes, D.; Arkenbout, G.J.; Bruinsma, O.S.L.; Koutsoukos, P.G.; Ulrich, J.

    1997-01-01

    Innovative separation techniques like melt crystallization have the potential to fulfil two important demands, namely: a significant reduction of energy consumption by the chemical industry, and the production of high quality products required by industry. Several industrial applications of melt

  9. A new technique for infrared scintillation measurements

    OpenAIRE

    Chiossi, F.; Brylew, K.; Borghesani, A. F.; Braggio, C.; Carugno, G.; Drozdowski, W.; Guarise, M.

    2016-01-01

    We propose a new technique to measure the infrared scintillation light yield of rare earth (RE) doped crystals by comparing it to near UV-visible scintillation of a calibrated Pr:(Lu$_{0.75}$Y$_{0.25}$)$_{3}$Al$_5$O$_{12}$ sample. As an example, we apply this technique to provide the light yield in visible and infrared range up to \\SI{1700}{nm} of this crystal.

  10. A new technique for infrared scintillation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Chiossi, F., E-mail: federico.chiossi@studenti.unipd.it [Dip. di Fisica e Astronomia and INFN, University of Padua, Via F. Marzolo 8, I-35131 Padova (Italy); Brylew, K. [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland); Borghesani, A.F. [CNISM Unit and Dip. di Fisica e Astronomia, University of Padua, Via F. Marzolo 8, I-35131 Padova (Italy); Braggio, C.; Carugno, G. [Dip. di Fisica e Astronomia and INFN, University of Padua, Via F. Marzolo 8, I-35131 Padova (Italy); Drozdowski, W. [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland); Guarise, M. [Dip. di Fisica e Astronomia and INFN, University of Padua, Via F. Marzolo 8, I-35131 Padova (Italy)

    2017-05-21

    We propose a new technique to measure the infrared scintillation light yield of rare earth doped crystals by comparing it to near UV–visible scintillation of a calibrated Pr:(Lu{sub 0.75}Y{sub 0.25}){sub 3}Al{sub 5}O{sub 12} sample. As an example, we apply this technique to provide the light yield in visible and infrared range up to 1700 nm of this crystal.

  11. Channeling through Bent Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Mack, Stephanie; /Ottawa U. /SLAC

    2012-09-07

    Bent crystals have demonstrated potential for use in beam collimation. A process called channeling is when accelerated particle beams are trapped by the nuclear potentials in the atomic planes within a crystal lattice. If the crystal is bent then the particles can follow the bending angle of the crystal. There are several different effects that are observed when particles travel through a bent crystal including dechanneling, volume capture, volume reflection and channeling. With a crystal placed at the edge of a particle beam, part of the fringe of the beam can be deflected away towards a detector or beam dump, thus helping collimate the beam. There is currently FORTRAN code by Igor Yazynin that has been used to model the passage of particles through a bent crystal. Using this code, the effects mentioned were explored for beam energy that would be seen at the Facility for Advanced Accelerator Experimental Tests (FACET) at a range of crystal orientations with respect to the incoming beam. After propagating 5 meters in vacuum space past the crystal the channeled particles were observed to separate from most of the beam with some noise due to dechanneled particles. Progressively smaller bending radii, with corresponding shorter crystal lengths, were compared and it was seen that multiple scattering decreases with the length of the crystal therefore allowing for cleaner detection of the channeled particles. The input beam was then modified and only a portion of the beam sent through the crystal. With the majority of the beam not affected by the crystal, most particles were not deflected and after propagation the channeled particles were seen to be deflected approximately 5mm. After a portion of the beam travels through the crystal, the entire beam was then sent through a quadrupole magnet, which increased the separation of the channeled particles from the remainder of the beam to a distance of around 20mm. A different code, which was developed at SLAC, was used to

  12. Growth and PhysioChemical Properties of Second-Order Nonlinear Optical L-Threonine Single Crystals

    Directory of Open Access Journals (Sweden)

    G. Ramesh Kumar

    2009-01-01

    Full Text Available The present aim of the paper is to grow and to study the various properties of L-threonine amino acid single crystal in various aspects. Crystal growth of L-threonine single crystals has been carried out with the help of crystallization kinetics. pH and deuteration effects on the properties of the grown crystals have been studied and the results presented in a lucid manner. The various second-order NLO parameters were evaluated using anharmonic oscillator model. Particle and ion irradiation effects on structural, optical, and surface properties of the crystals have also been studied in detail.

  13. Dissolution enhancement of Deflazacort using hollow crystals prepared by antisolvent crystallization process.

    Science.gov (United States)

    Paulino, A S; Rauber, G; Campos, C E M; Maurício, M H P; de Avillez, R R; Capobianco, G; Cardoso, S G; Cuffini, S L

    2013-05-13

    Deflazacort (DFZ), a derivate of prednisolone, is a poorly soluble drug which has been proposed to have major advantages over other corticosteroids. Poorly soluble drugs present limited bioavailability due to their low solubility and dissolution rate and several strategies have been developed in order to find ways to improve them. In general, pharmaceutical laboratories use a micronized process to reduce the particle size in order to increase the dissolution of the drugs. However, this process causes changes such as polymorphic transitions, particle agglomeration and a reduction in fluidity and wettability. These solid-state properties affect the dissolution behavior and stability performance of drugs. Crystallization techniques are widely used in the pharmaceutical industry and antisolvent crystallization has been used to obtain ultrafine particles. In this study, DFZ was investigated in terms of its antisolvent crystallization in different solvents and under various preparation conditions (methanol/water ratio, stirring and evaporation rate, etc.), in order to compare the physicochemical properties between crystallized samples and raw materials available on the Brazilian market with and without micronization. Crystalline structure, morphology, and particle size, and their correlation with the Intrinsic Dissolution Rate (IDR) and dissolution profile as relevant biopharmaceutical properties were studied. Crystallization conditions were achieved which provided crystalline samples of hollow-shaped crystals with internal channels, which increased the dissolution rate of DFZ. The antisolvent crystallization process allowed the formation of hollow crystals, which demonstrated a better dissolution profile than the raw material (crystalline and micronized), making this a promising technique as a crystallization strategy for improving the dissolution and thus the bioavailability of poorly soluble drugs. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Variable-metric diffraction crystals for x-ray optics

    International Nuclear Information System (INIS)

    Smither, R.K.; Fernandez, P.B.

    1992-01-01

    A variable-metric (VM) crystal is one in which the spacing between the crystalline planes changes with position in the crystal. This variation can be either parallel to the crystalline planes or perpendicular to the crystalline planes of interest and can be produced by either introducing a thermal gradient in the crystal or by growing a crystal made of two or more elements and changing the relative percentages of the two elements as the crystal is grown. A series of experiments were performed in the laboratory to demonstrate the principle of the variable-metric crystal and its potential use in synchrotron beam lines. One of the most useful applications of the VM crystal is to increase the number of photons per unit bandwidth in a diffracted beam without losing any of the overall intensity. In a normal synchrotron beam line that uses a two-crystal monochromator, the bandwidth of the diffracted photon beam is determined by the vertical opening angle of the beam which is typically 0.10--0.30 mrad or 20--60 arcsec. When the VM crystal approach is applied, the bandwidth of the beam can be made as narrow as the rocking curve of the diffracting crystal, which is typically 0.005--0.050 mrad or 1--10 arcsec. Thus a very large increase of photons per unit bandwidth (or per unit energy) can be achieved through the use of VM crystals. When the VM principle is used with bent crystals, new kinds of x-ray optical elements can be generated that can focus and defocus x-ray beams much like simple lenses where the focal length of the lens can be changed to match its application. Thus both large magnifications and large demagnifications can be achieved as well as parallel beams with narrow bandwidths

  15. HYDROPONICS TECHNOLOGY TO GROW PLANTS WITHOUT SOIL

    Directory of Open Access Journals (Sweden)

    P. V. Shishkin

    2017-01-01

    Full Text Available The method of hydroponics for growing plants without soil has been developed, where the many advantages are: the high technological performance; reduce of expenses; economy in watering and fertilizers due to lack of drainage system and extra engineering needed for solution circulation; reduce of exploitations expenses due to lack of soil tilling. There is also no problem concerning the root rots that are typical for all methods of growing plants without soil. This allows growing the plants with large root volume and prolonged period of vegetation. Efficiency of this system  has been proven by multi-year experiments. It was shown  that  vegetable crop  such as cucumber,  the root system of which is very sensible to oxygen deficiency, well grew, developed and gave fruits on the vegetation tray.

  16. Projected changes in Malawi's growing season

    Science.gov (United States)

    Vizy, Edward K.; Cook, Kerry H.; Chimphamba, James; McCusker, Brent

    2015-09-01

    Regional climate model projections at 30-km resolution are used to predict future mid-century and late-century growing season changes over Malawi due to global warming under the Representative Concentration Pathway 8.5 business-as-usual emissions forcing scenario. Three different methods for estimating growing season characteristics are applied and evaluated. All three methods yield reasonable growing season length, onset, and demise date estimates over Malawi given the wide range of uncertainty of the observations. The projections indicate the likelihood for a shorter growing season in the future over Malawi south of 13.5°S. At mid-century the growing season length is predicted to be 20-40 % (20-55 days) shorter over the southernmost districts and 5-20 % (5-30 days) shorter over the central districts. By late-century the length is predicted to be 25-55 % (20-70 days) shorter with significant differences extending into northern Malawi. The shorter growing season is primarily associated with an earlier demise date, as no significant change in the onset date is predicted. Analysis of the regional circulation and horizontal moisture flux transport indicates that the earlier demise is associated with an intensification of the thermal low over the Kalahari Desert to the south and west of Malawi and an expansion of the mid-tropospheric Kalahari anticyclone over southern Africa. The stronger thermal low/anticyclone enhances the moisture flux divergence over Malawi suppressing the convective activity at the end of the wet season.

  17. 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

  18. Walkout in Crystal City

    Science.gov (United States)

    Barrios, Greg

    2009-01-01

    When students take action, they create change that extends far beyond the classroom. In this article, the author, who was a former teacher from Crystal City, Texas, remembers the student walkout that helped launch the Latino civil rights movement 40 years ago. The Crystal City student walkout remains a high point in the history of student activism…

  19. Demonstration of Crystal Structure.

    Science.gov (United States)

    Neville, Joseph P.

    1985-01-01

    Describes an experiment where equal parts of copper and aluminum are heated then cooled to show extremely large crystals. Suggestions are given for changing the orientation of crystals by varying cooling rates. Students are more receptive to concepts of microstructure after seeing this experiment. (DH)

  20. 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....