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Sample records for aluminum-induced crystallization comparison

  1. H-plasma-assisted aluminum induced crystallization of amorphous silicon

    Institute of Scientific and Technical Information of China (English)

    Li Juan; Liu Ning; Luo Chong; Meng Zhiguo; Xiong Shaozhen; Hoi Sing Kwok

    2012-01-01

    A technique to improve and accelerate aluminum induced crystallization (AIC) by using hydrogen plasma is proposed.Raman spectroscopy and secondary ion mass spectrometry of crystallized poly-Si thin films show that hydrogen plasma radicals reduce the crystallization time of AIC.This technique shortens the annealing time from 10 to 4 h and increases the Hall mobility from 22.1 to 42.5 cm2/(V·s).The possible mechanism of AIC assisted by hydrogen radicals is also discussed.

  2. Poly-Si films with low aluminum dopant containing by aluminum-induced crystallization

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Typically, highly p-doped (2×10 18 cm -3 ) poly-Si films fabricated by the aluminum induced layer exchange (ALILE) process are not suitable for solar cell absorber layers. In this paper, the fabrication of high-quality, continuous polycrystalline silicon (poly-Si) films with lower doping concentrations (2×10 16 cm -3 ) using aluminum-induced crystallization (AIC) is reported. Secondary-ion-mass spectroscopy (SIMS) results showed that annealing at different temperature profiles leads to a variety of Al concentrations. Hall Effect measurements revealed that Al dopant concentration depends on the annealing temperature and temperature profile. Raman spectral analysis indicated that samples prepared via AIC contain some regions with small grains.

  3. Fabrication of Poly-Si Thin Film on Glass Substrate by Aluminum-induced Crystallization

    Institute of Scientific and Technical Information of China (English)

    XU Man; XIA Donglin; YANG Sheng; ZHAO Xiujian

    2006-01-01

    Amorphous silicon (a-Si) thin films were deposited on glass substrate by PECVD,and polycrystalline silicon (poly-Si) thin films were prepared by aluminum-induced crystallization (AIC). The effects of annealing temperature on the microstructure and morphology were investigated. The AIC poly-Si thin films were characterized by XRD, Raman and SEM. It is found that a-Si thin film has a amorphous structure after annealing at 400 ℃ for 20 min, a-Si films begin to crystallize after annealing at 450 ℃ for 20 min, and the crystallinity of a-Si thin films is enhanced obviously with the increment of annealing temperature.

  4. Structural properties of a-Si films and their effect on aluminum induced crystallization

    International Nuclear Information System (INIS)

    In this paper, we report the influence of the structural properties of amorphous silicon (a-Si) on its subsequent crystallization behavior via the aluminum induced crystallization (AIC) method. Two distinct a-Si deposition techniques, electron beam evaporation and plasma enhanced chemical vapor deposition (PECVD), are compared for their effect on the overall AIC kinetics as well as the properties of the final poly-crystalline (poly-Si) silicon film. Raman and FTIR spectroscopy results indicate that the PECVD grown a-Si films has higher intermediate-range order, which is enhanced for increased hydrogen dilution during deposition. With increasing intermediate-range order of the a-Si, the rate of AIC is diminished, leading larger poly-Si grain size

  5. Influence of precursor a-Si:H dehydrogenation on the aluminum induced crystallization process

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Weiyuan, E-mail: weiyuan.duan0924@mail.sim.ac.cn [New Energy Technology Center, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 235 Chengbei Road, Jiading, Shanghai 200050 (China); University of the Chinese Academy of Sciences, Beijing 100039 (China); Qiu, Yu, E-mail: yuqiu@mail.sim.ac.cn [New Energy Technology Center, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 235 Chengbei Road, Jiading, Shanghai 200050 (China); Zhang, Liping; Yu, Jian; Bian, Jiantao; Liu, Zhengxin [New Energy Technology Center, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 235 Chengbei Road, Jiading, Shanghai 200050 (China)

    2014-07-01

    Polycrystalline silicon (poly-Si) thin film grown on low cost substrates such as glass at low temperature is an attractive material for cost-effective solar cells. This work studied the influence of dehydrogenation of a-Si:H precursor on the crystallization behavior by aluminum induced crystallization (AIC) process below the eutectic temperature of 577 °C. The a-Si:H films were deposited by PECVD and aluminum was evaporated in a vacuum evaporation equipment, respectively. Some of the a-Si:H thin films were dehydrogenated in nitrogen atmosphere before aluminum evaporation. It was found that hydrogen content in a-Si:H drops to a stable value after annealing at 480 °C for 1 h. Micro-Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy and scanning electron microscopy measurements were used to investigate the structural characteristics of the a-Si:H and the prepared poly-Si thin films. Our results show that although the dehydrogenation increases AIC temperature and reduces AIC rate, it can improve microstructural quality of poly-Si thin films, leading to less tensile stress, higher crystallinity, smoother and more conformal surface morphology. - Highlights: • The influence of a-Si:H precursor dehydrogenation on AIC process was studied. • Dehydrogenation can improve microstructural quality of poly-Si thin films. • Smoother surface morphology can be observed on dehydrogenation samples after AIC. • The dehydrogenation process is necessary for fabricating high quality solar cells.

  6. P-type poly-Si prepared by low-temperature aluminum-induced crystallization and doping for solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Yasuhiro; Yu, Zhenrui; Morales-Acevedo, Arturo [CINVESTAV-IPN, Mexico, D.F. (Mexico)

    2000-07-01

    P-type poly-Si thin films prepared by low temperature aluminum-induced crystallization and doping are reported. The starting material was boron-doped a-Si:H prepared by PECVD on glass substrates. Aluminum layers with different thickness were evaporated on a-Si:H surface and conventional thermal annealing was performed at temperatures ranging from 300 to 550 Celsius degrees. XRD, SIMS, and Hall effect measurements were carried out to characterize the annealed Al could be crystallized at temperature as low as 300 Celsius degrees in 60 minutes. This material has high carrier concentration as well as high Hall mobility and can be used as a p-layer of seed layer for thin film poly-Si solar cells. The technique reported here is compatible with PECVD process. [Spanish] Se informa sobre la preparacion de peliculas delgadas tipo P y Poli-Si mediante la cristalizacion inducida de aluminio a baja temperatura y el dopado. El material inicial era de boro dopado y a-Si:H preparado PECVD sobre substratos de vidrio. Se evaporaron capas de aluminio de diferente espesor sobre una superficie de a-Si:H y se llevo a cabo un destemplado termico convencional a temperaturas que varian entre 300 y 500 grados Celsius. Se llevaron a cabo mediciones de XRB, SIMS y del efecto Hall para caracterizar el aluminio destemplado para que pudiera ser cristalizado a temperaturas tan bajas como 300 grados Celsius en 60 minutos. Este material tiene una alta concentracion portadora asi como una alta movilidad Hall y puede usarse como una capa de semilla para celdas solares de pelicula delgada Poli-Si. La tecnica reportada aqui es compatible con el proceso PECVD.

  7. Quercetin attenuates neuronal death against aluminum-induced neurodegeneration in the rat hippocampus.

    Science.gov (United States)

    Sharma, D R; Wani, W Y; Sunkaria, A; Kandimalla, R J; Sharma, R K; Verma, D; Bal, A; Gill, K D

    2016-06-01

    Aluminum is a light weight and toxic metal present ubiquitously on earth, which has gained considerable attention due to its neurotoxic effects. It also has been linked ecologically and epidemiologically to several neurological disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), Guamanian-Parkinsonian complex and Amyotrophic lateral sclerosis (ALS). The mechanism of aluminum neurotoxicity is poorly understood, but it is well documented that aluminum generates reactive oxygen species (ROS). Enhanced ROS production leads to disruption of cellular antioxidant defense systems and release of cytochrome c (cyt-c) from mitochondria to cytosol resulting in apoptotic cell death. Quercetin (a natural flavonoid) protects it from oxidative damage and has been shown to decrease mitochondrial damage in various animal models of oxidative stress. We hypothesized that if oxidative damage to mitochondria does play a significant role in aluminum-induced neurodegeneration, and then quercetin should ameliorate neuronal apoptosis. Administration of quercetin (10mg/kg body wt/day) reduced aluminum (10mg/kg body wt/day)-induced oxidative stress (decreased ROS production, increased mitochondrial superoxide dismutase (MnSOD) activity). In addition, quercetin also prevents aluminum-induced translocation of cyt-c, and up-regulates Bcl-2, down-regulates Bax, p53, caspase-3 activation and reduces DNA fragmentation. Quercetin also obstructs aluminum-induced neurodegenerative changes in aluminum-treated rats as seen by Hematoxylin and Eosin (H&E) staining. Further electron microscopic studies revealed that quercetin attenuates aluminum-induced mitochondrial swelling, loss of cristae and chromatin condensation. These results indicate that treatment with quercetin may represent a therapeutic strategy to attenuate the neuronal death against aluminum-induced neurodegeneration. PMID:26944603

  8. Improving the Microstructure and Electrical Properties of Aluminum Induced Polysilicon Thin Films Using Silicon Nitride Capping Layer

    Directory of Open Access Journals (Sweden)

    Min-Hang Weng

    2014-01-01

    Full Text Available We investigated the capping layer effect of SiNx (silicon nitride on the microstructure, electrical, and optical properties of poly-Si (polycrystalline silicon prepared by aluminum induced crystallization (AIC. The primary multilayer structure comprised Al (30 nm/SiNx (20 nm/a-Si (amorphous silicon layer (100 nm/ITO coated glass and was then annealed in a low annealing temperature of 350°C with different annealing times, 15, 30, 45, and 60 min. The crystallization properties were analyzed and verified by X-ray diffraction (XRD and Raman spectra. The grain growth was analyzed via optical microscope (OM and scanning electron microscopy (SEM. The improved electrical properties such as Hall mobility, resistivity, and dark conductivity were investigated by using Hall and current-voltage (I-V measurements. The results show that the amorphous silicon film has been effectively induced even at a low temperature of 350°C and a short annealing time of 15 min and indicate that the SiNx capping layer can improve the grain growth and reduce the metal content in the induced poly-Si film. It is found that the large grain size is over 20 μm and the carrier mobility values are over 80 cm2/V-s.

  9. Aluminum-induced pneumoconiosis confirmed by analytical scanning electron microscopy: A case report and review of the literature.

    Science.gov (United States)

    Carney, John; McAdams, Page; McCluskey, James; Roggli, Victor L

    2016-01-01

    Aluminum-induced lung injury is an uncommon, yet recognized pneumoconiosis capable of causing severe interstitial fibrosis. Important attention to the clinical history including occupational exposure is an essential component to making the correct diagnosis, despite which careful examination of the lung specimen is necessary to exclude other more common disease entities. We present a case of aluminum-induced pneumoconiosis in the setting of a bilateral lung transplant patient. Additionally, we review the literature on aluminum-induced pneumoconiosis and demonstrate the use of ancillary techniques including backscattered electron imaging and energy-dispersive spectrometry to aid in diagnosis. PMID:26895029

  10. Role of ethanol on aluminum induced biochemical changes on rat brain

    OpenAIRE

    Nayak, Parsunpriya; Kumar Das, Subir; Vasudevan, D M

    2006-01-01

    Aluminum and alcohol, both are well-accepted neurotoxin. The plausible mechanisms for their neurotoxicity are also common. Therefore, the effect of ethanol on aluminum induced biochemical changes in rat brain is being studied. In the present study, ethanol exposure significantly affected the aluminum and protein content of brain. The activities of acid phosphatase and alkaline phosphatase were also changed. Aluminum exposure, on the other hand, contributed significantly in the alterations of ...

  11. Metal-induced crystallization fundamentals and applications

    CERN Document Server

    Wang, Zumin; Mittemeijer, Eric J

    2014-01-01

    Introduction to Metal-Induced CrystallizationAtomic Mechanisms and Interface Thermodynamics of Metal-Induced Crystallization of Amorphous Semiconductors at Low TemperaturesThermodynamics and Kinetics of Layer Exchange upon Low-Temperature Annealing Amorphous Si/Polycrystalline Al Layered StructuresMetal-Induced Crystallization by Homogeneous Insertion of Metallic Species in Amorphous SemiconductorsAluminum-Induced Crystallization: Applications in Photovoltaic TechnologiesApplications of Metal-Induced Crystallization for Advanced Flat-Panel DisplaysLaser-Assisted Meta

  12. Role of Al2O3 intermediate layer for improving the quality of polycrystalline-silicon film in inverted aluminum-induced layer exchange

    International Nuclear Information System (INIS)

    Highlights: • Al2O3 intermediate layer deposited by ALD was introduced in inverted-ALILE process. • Poly-Si with 93% (1 0 0)-oriented crystals fraction and 28-μm average grain size was achieved at 4-nm Al2O3 intermediate layer. • Smooth surface morphology and lower defects of poly-Si was achieved. • An a-AlOx layer exists at the poly-Si/Al interface after inverted-ALILE process. - Abstract: A thin Al2O3 intermediate layer prepared by atomic layer deposition was introduced into inverted aluminum-induced layer exchange (inverted-ALILE) to form high-quality polycrystalline silicon (poly-Si) thin layer. It was demonstrated that the continuity and quality of poly-Si were obviously improved by the Al2O3 layer. The fraction of (1 0 0)-oriented crystals reached 93%, and the average grain size of 28 μm with uniform surface morphology and low defect density were achieved at the optimal Al2O3 thickness of 4 nm. It was also found that an a-AlOx layer always existed at the poly-Si/Al interface after inverted-ALILE process, which is independent on the original surface states. The results suggested that the thin poly-Si layer would be a promising epitaxial template for Si based thin film solar cells

  13. Comparison of distillation and crystallization refining of some binary systems

    International Nuclear Information System (INIS)

    The analytic view of the yield g (when the efficiency of distillation and normal directional crystallization are equal) from coefficients of distribution have been ascertained: g = α1/(k-1) at α < 1, k > 1 and g = k1/(α-1) at ? > 1, k < 1 (α and k are coefficients of distribution at distillation and crystallization correspondingly). The values of g for line of systems (Ge-Al, Te-Se, Te-Pb, Ge-Be, Ge-Si, Ge-Ga, Ge-As, Ge-B, Zn-Cd) have been calculated (< 0,1; ∼ 0,1; ∼ 0,5; ∼ 0,6;∼ 0,7; ∼ 0,7; ∼ 0,8; ∼ 0,8 and ∼ 0,8 correspondingly)

  14. Focusing characteristics of diamond crystal x-ray monochromators. An experimental and theoretical comparison

    DEFF Research Database (Denmark)

    Rio, M.S. del; Grübel, G.; Als-Nielsen, J.;

    1995-01-01

    Perfect crystals in transmission (Laue) geometry can be used effectively for x-ray monochromators, and moreover, perfect Laue crystals show an interesting focusing effect when the incident beam is white and divergent. This focusing is directly dependent on the incident beam divergence and on the ...... from a diamond crystal in Lane geometry, and we analyze and explain the results by comparison with ray-tracing simulations. (C) 1995 American Institute of Physics.......Perfect crystals in transmission (Laue) geometry can be used effectively for x-ray monochromators, and moreover, perfect Laue crystals show an interesting focusing effect when the incident beam is white and divergent. This focusing is directly dependent on the incident beam divergence and on the...... diffraction profile width of the crystal. The aim of this work is to study whether this property can be used for focusing a synchrotron x-ray beam, and to obtain quantitatively the dimensions of the resulting monochromatic beam. We have experimentally measured the size of an undulator beam after diffraction...

  15. Strength of orthoenstatite single crystals at mantle pressure and temperature and comparison with olivine

    Science.gov (United States)

    Raterron, Paul; Fraysse, Guillaume; Girard, Jennifer; Holyoke, Caleb W.

    2016-09-01

    Oriented single crystals of orthopyroxenes (OPx) were deformed in axisymmetric compression in the D-DIA at pressure and temperature in excess of 3 GPa and 1040 °C. Two crystal orientations were tested with the compression axis parallel to either [101]c crystallographic direction, to investigate [001](100) dislocation slip-system strength, or [011]c direction to investigate [001](010) slip-system strength. These slip systems are the most active in orthopyroxenes. Applied differential stresses and specimen strain rates were measured in situ by synchrotron X-ray diffraction and radiography. We used these data and comparison with previously reported low-pressure flow laws for protoenstatite and orthoenstatite to determine the power law parameters for the deformation of orthoenstatite crystals, which characterize OPx dislocation slip-system strengths. Applying these laws at reasonable mantle stresses along oceanic and continental geotherms indicates that OPx [001](100) slip system is weaker than OPx [001](010) slip system to ∼260 km depth where the strengths converge. It also indicates that both OPx slip systems are significantly stronger than olivine slip systems throughout the upper mantle, except in the upper most mantle, in the lithosphere, were OPx [001](100) slip system may be as weak or even weaker than olivine [100](010) easy slip system.

  16. Solvent phase characterization of lanthanide and americium complexes with malonamide and ter-pyridine ligands. Comparison with single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Den Auwer, C.; Grigoriev, M.S.; Charbonnel, M.C.; Presson, M.T. [CEA/VALRHO - site de Marcoule, Dept. de Recherche en Retraitement et en Vitrification, DRRV, 30 - Marcoule (France); Den Auwer, C. [Laboratoire pour l' Utilisation du Rayonnement Electromagnetique (LURE), Paris-11 Univ., 91 - Orsay (France); Grigoriev, M.S. [Institute of Physical Chemistry, Russian Academy of Sciences, Moscow (Russian Federation)

    2000-07-01

    This work presents our latest results on the coordination polyhedron of the tetranitrate lanthanide complexes with aza and carboxy ligands. Structures in the solid state have been determined by X-ray single crystal diffraction and solution studies have been carried out by X-ray Absorption Spectroscopy at the cation L{sub III} edge. Comparison is made with the Am cation. (authors)

  17. Solvent phase characterization of lanthanide and americium complexes with malonamide and ter-pyridine ligands. Comparison with single crystals

    International Nuclear Information System (INIS)

    This work presents our latest results on the coordination polyhedron of the tetranitrate lanthanide complexes with aza and carboxy ligands. Structures in the solid state have been determined by X-ray single crystal diffraction and solution studies have been carried out by X-ray Absorption Spectroscopy at the cation LIII edge. Comparison is made with the Am cation. (authors)

  18. Optical, thermal, and mechanical characterization of photonic crystal fibers: results and comparisons

    Science.gov (United States)

    Borzycki, Krzysztof; Kobelke, Jens; Schuster, Kay; Wójcik, Jan

    2010-04-01

    Six photonic crystal fibers (PCFs) were characterized at NIT laboratory participating in COST Action 299 "FIDES", allowing for comparisons of properties and their dependence on fiber design. Samples tested included three nonlinear fibers with germanium doped core, two fibers with un-doped core and honeycomb photonic structure, and a "PANDAlike" PCF with a pair of large holes along an un-doped core. Tests included optical time domain reflectometer (OTDR) measurements, spectral loss, polarization mode dispersion (PMD) and its variations with temperature, fiber twist and axial strain. Elastooptic coefficient was measured for 2 fibers. Most samples exhibited high PMD, up to 3 ps/m. PMD was usually reduced by twisting the fiber, but twist sensitivity varied widely. The "PANDA-like" PCF, however, had PMD virtually unaffected by both twist and tensile strain; the latter property made it different from true PANDA fiber tested for comparison. Intensity of backscattering in each PCF was stronger compared to a standard telecom single mode fiber (SMF), by a factor up to 110x.

  19. Investigation of phase explosion in aluminum induced by nanosecond double pulse technique

    International Nuclear Information System (INIS)

    Highlights: • Single and collinear double pulse configurations were used for laser ablation of aluminum target in air. • The 5, 10, 15 and 20 ns delay times between pre pulse and main pulse in double pulse arrangement was investigated. • In comparison between single and double pulse regimes, the phase explosion threshold fluence is decreased in double pulse configuration. • The plasma shielding effect reduces the crater depth in lower laser fluence in double pulse configuration rather that its in single pulse configuration. - Abstract: In this paper, the influence of double pulse technique on phase explosion threshold in laser ablation of an aluminum target is investigated. Single and double pulse laser ablation of aluminum target was performed by a high power Nd:YAG laser beam in ambient air. In the double pulse excitation, the two pulses were from a single laser source which separated by a delay time in the range of 5–20 ns. Measuring ablation depth and rate, the phase explosion threshold was estimated in double pulse configuration as well as in the single pulse regime. The results show that in comparison between single and double pulse regimes, the phase explosion threshold fluence is decreased in double pulse configuration. The lowest phase explosion threshold fluence of 0.9 J/cm2 was obtained at 5 ns delay time. The results also show that plasma shielding effect reduced crater depth at a laser fluence which depended on the laser ablation configuration (single pulse or double pulse). The reduction of crater depth occurs at lower laser fluences for double pulse regime

  20. Protective effects of low-intensity pulsed ultrasound on aluminum-induced cerebral damage in Alzheimer's disease rat model

    Science.gov (United States)

    Lin, Wei-Ting; Chen, Ran-Chou; Lu, Wen-Wei; Liu, Shing-Hwa; Yang, Feng-Yi

    2015-04-01

    The protein expressions of neurotrophic factors can be enhanced by low-intensity pulsed ultrasound (LIPUS) stimulation in the brain. The purpose of this study was to demonstrate the protective effect of LIPUS stimulation against aluminum-induced cerebral damage in Alzheimer's disease rat model. LIPUS was administered 7 days before each aluminum chloride (AlCl3) administration, and concomitantly given with AlCl3 daily for a period of 6 weeks. Neurotrophic factors in hippocampus were measured by western blot analysis. Behavioral changes in the Morris water maze and elevated plus maze were examined in rats after administration of AlCl3. Various biochemical analyses were performed to evaluate the extent of brain damages. LIPUS is capable of prompting levels of brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), and vascular endothelial growth factor (VEGF) in rat brain. AlCl3 administration resulted in a significant increase in the aluminum concentration, acetylcholinesterase activity and beta-amyloid (Aβ) deposition in AlCl3 treated rats. LIPUS stimulation significantly attenuated aluminum concentration, acetylcholinesterase activity, Aβ deposition and karyopyknosis in AlCl3 treated rats. Furthermore, LIPUS significantly improved memory retention in AlCl3-induced memory impairment. These experimental results indicate that LIPUS has neuroprotective effects against AlCl3-induced cerebral damages and cognitive dysfunction.

  1. Luminescence of SiO2 and GeO2 crystals with rutile structure. Comparison with α-quartz crystals and relevant glasses (Review Article)

    Science.gov (United States)

    Trukhin, A. N.

    2016-07-01

    Luminescence properties of SiO2 in different structural states are compared. Similar comparison is made for GeO2. Rutile and α-quartz structures as well as glassy state of these materials are considered. Main results are that for α-quartz crystals the luminescence of self-trapped exciton is the general phenomenon that is absent in the crystal with rutile structure. In rutile structured SiO2 (stishovite) and GeO2 (argutite) the main luminescence is due to a host material defect existing in as-received (as-grown) samples. The defect luminescence possesses specific two bands, one of which has a slow decay (for SiO2 in the blue and for GeO2, in green range) and another, a fast ultraviolet (UV) band (4.75 eV in SiO2 and at 3 eV in GeO2). In silica and germania glasses, the luminescence of self-trapped exciton coexists with defect luminescence. The latter also contains two bands: one in the visible range and another in the UV range. The defect luminescence of glasses was studied in details during last 60-70 years and is ascribed to oxygen deficient defects. Analogous defect luminescence in the corresponding pure nonirradiated crystals with α-quartz structure is absent. Only irradiation of a α-quartz crystal by energetic electron beam, γ-rays and neutrons provides defect luminescence analogous to glasses and crystals with rutile structure. Therefore, in glassy state the structure containing tetrahedron motifs is responsible for existence of self-trapped excitons and defects in octahedral motifs are responsible for oxygen deficient defects.

  2. Crystal growth and comparison of vibrational and thermal properties of semi-organic nonlinear optical materials

    Indian Academy of Sciences (India)

    S Gunasekaran; G Anand; R Arun Balaji; J Dhanalakshmi; S Kumaresan

    2010-10-01

    Single crystals of urea thiourea mercuric sulphate (UTHS) and urea thiourea mercuric chloride (UTHC), semi-organic nonlinear optical materials, were grown by low-temperature solution growth technique by slow evaporation method using water as the solvent. Good quality single crystals were grown within three weeks. The nonlinear nature of the crystals was confirmed by SHG test. The UV–Vis spectrum showed the transmitting ability of the crystals in the entire visible region. FTIR spectrum was recorded and vibrational assignments were made. The degree of dopant inclusion was ascertained by AAS. The TGA–DTA studies showed the thermal properties of the crystals.

  3. A new single crystal diamond dosimeter for small beam: comparison with different commercial active detectors

    International Nuclear Information System (INIS)

    Recent developments of new therapy techniques using small photon beams, such as stereotactic radiotherapy, require suitable detectors to determine the delivered dose with a high accuracy. The dosimeter has to be as close as possible to tissue equivalence and to exhibit a small detection volume compared to the size of the irradiation field, because of the lack of lateral electronic equilibrium in small beam. Characteristics of single crystal diamond (tissue equivalent material Z = 6, high density) make it an ideal candidate to fulfil most of small beam dosimetry requirements. A commercially available Element Six electronic grade synthetic diamond was used to develop a single crystal diamond dosimeter (SCDDo) with a small detection volume (0.165 mm3). Long term stability was studied by irradiating the SCDDo in a 60Co beam over 14 h. A good stability (deviation less than ± 0.1%) was observed. Repeatability, dose linearity, dose rate dependence and energy dependence were studied in a 10 × 10 cm2 beam produced by a Varian Clinac 2100 C linear accelerator. SCDDo lateral dose profile, depth dose curve and output factor (OF) measurements were performed for small photon beams with a micro multileaf collimator m3 (BrainLab) attached to the linac. This study is focused on the comparison of SCDDo measurements to those obtained with different commercially available active detectors: an unshielded silicon diode (PTW 60017), a shielded silicon diode (Sun Nuclear EDGE), a PinPoint ionization chamber (PTW 31014) and two natural diamond detectors (PTW 60003). SCDDo presents an excellent spatial resolution for dose profile measurements, due to its small detection volume. Low energy dependence (variation of 1.2% between 6 and 18 MV photon beam) and low dose rate dependence of the SCDDo (variation of 1% between 0.53 and 2.64 Gy min−1) are obtained, explaining the good agreement between the SCDDo and the efficient unshielded diode (PTW 60017) in depth dose curve measurements. For

  4. Comparison of Lithium Gadolinium Borate Crystal Shards in Scintillating and Nonscintillating Plastic Matrices

    OpenAIRE

    Kazkaz, Kareem; Bowden, Nathaniel S.; Pedretti, Marisa

    2011-01-01

    We present a method for detecting neutrons using scintillating lithium gadolinium borate crystal shards in a plastic matrix while maintaining high gamma rejection. We have procured two cylindrical detectors, 5"\\times5", containing 1% crystal by mass. Crystal shards have a typical dimension of 1 mm. One detector was made with scintillating plastic, and one with nonscintillating plastic. Pulse shape analysis was used to reject gamma ray backgrounds. The scintillating detector was measured to ha...

  5. Control of defects in a novel aluminum-induced heteroepitaxial growth of AlxGal-xP nanocrystals on silicon nanowires

    International Nuclear Information System (INIS)

    Aluminum-induced heteroepitaxial growth of aluminum gallium phosphide nanocrystals (AlxGal-xP NCs) has been achieved on both silicon substrate and the tips of Al-catalyzed silicon nanowires (Si NWs). Al-induced growth is a silicon complementary metal–oxide-semiconductor compatible solution, and a growth mechanism of AlxGal-xP NCs was proposed. The decrease in structural defects in AlxGal-xP NCs grown heteroepitaxially on Si NWs was confirmed by transmission electron microscopy and Raman spectroscopy

  6. Comparison Study of Critical Properties of the Bond-Diluted Blume-Capel Model under the Condition of Two Different Random Crystal Fields

    Institute of Scientific and Technical Information of China (English)

    YAN Shi-Lei; DENG Ling-Ling

    2003-01-01

    Critical properties of the bond diluted Blume-Capel model with random crystal field are considered inthe framework of the effective field theory. Special emphasis is placed on the comparison study of critical propertiesunder the condition of two different random crystal fields on square lattice. Calculated results show that the randomcrystal field plays an important role in the determination of the order of phase transition. The distributions of differentrandom crystal fields, such as symmetrical and dilution crystal field, lead to apparent characteristic behaviors. We notonly give the description of a detailed phase diagram but also compare the difference between the critical properties oftwo different random crystal field distributions. This comparison study has not been revealed in previous reports.

  7. Comparison between different dispersion engineering methods in slow light photonic crystal waveguides

    DEFF Research Database (Denmark)

    Wang, Fengwen; Jensen, Jakob Søndergaard; Sigmund, Ole

    2011-01-01

    This paper compares the performance of different dispersion engineering methods in slow light photonic crystal waveguides, i.e., geometrical parameter optimization and topology optimization. In both methods, the design robustness is enforced by considering the dilated, intermediate and eroded...

  8. Comparison between correlation crystal field calculations using extended basis sets and two-electron operators

    International Nuclear Information System (INIS)

    Full text: Faucher and co-workers have carried out several studies of the effect of electron correlation on the crystal-field splitting of 4fN configurations of lanthanide ions in solids. In their approach the 4fN configuration is supplemented by the 4fN-1 6p configuration. On the other hand, Reid, Burdick, and coworkers have carried out many parameter fits using pure 4fN model spaces, with the one-electron crystal field operators supplemented with two-electron correlation crystal field operators. Both approaches lead to better fits to the experimental data, but since the basis sets are different, it is difficult to compare the resulting parameters. In this work we use the matrices generated by Faucher's calculations to calculate the equivalent two-electron correlation crystal field parametrization in the 4fN model space

  9. Crystal Structures of Precise Functional Copolymers: Atomistic Molecular Dynamics Simulations and Comparisons with Experiments

    Science.gov (United States)

    Trigg, Edward B.; Stevens, Mark J.; Winey, Karen I.

    Layered crystal structures have been observed in linear poly(ethylene-co-acrylic acid) in which the carboxylic acid groups are placed precisely every 21 carbon atoms along the backbone. The alkane segments form structures resembling orthorhombic polyethylene crystals, while the acid groups form continuous domains that may act as pathways for ion conduction. Further details of the crystal structure have been difficult to elucidate experimentally, but could be important for understanding structure-property relationships. Here, two classes of crystal structures are evaluated via atomistic molecular dynamics: extended chain structures, wherein the polymer backbones are highly extended in near-trans conformations, and adjacent reentry structures, wherein the polymer backbones conform in adjacent reentry loops near the site of each covalently-bonded acid group. Energies of relaxed structures and hydrogen bonding states are compared, and X-ray scattering and other experimental data is compared with the simulation results.

  10. Comparison of the mechanism of gap formation for tri- and bi-component phononic crystal

    Institute of Scientific and Technical Information of China (English)

    Zhao Hong-Gang; Wen Ji-Hong; Liu Yao-Zong; Yu Dian-Long; Wang Gang; Wen Xi-Sen

    2008-01-01

    Using an exact Mie scattering solution, this paper investigates the mode conversions during the Mie scattering of a single bi- or one-component sphere in unbounded epoxy. Then the formation mechanism of the first complete gap in the corresponding tri- or bi-component phononic crystal is investigated by the multiple-scattering method. It is shown that the heavy density of the scatterer plays an essential role in the Mie resonance and the formation of the gaps for both types of the phononic crystals. For the tri-component phononic crystal, the gap is mainly induced by the Mie resonance of the single scatterer. For the bi-component phononic crystal, the transverse wave (by mode-conversion during the Mie scattering under a longitudinal wave incidence) is modulated by the periodicity and governed by the Bloch theory,which induces the gap cooperatively.

  11. Defect Density Comparison of Detached versus Attached Bridgman Grown Germanium Crystals

    Science.gov (United States)

    Schweizer, M.; Cobb, S. D.; Volz, M. P.; Szofran, F. R.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Semiconductor Bridgman growth without contact between the growing crystal and the growth ampoule has been observed on Earth in the last few years during several experiments. Previously, this so-called detached or dewetted growth phenomenon occurred preferentially under microgravity conditions due to the absence of the hydrostatic pressure. Many theoretical as well as experimental investigations helped to provide a better understanding of the mechanism and to identify the parameters leading to the detachment. Thus, recent attempts to get stable detached growth under terrestrial conditions by Duffar et al. growing III-V compounds and our own group with germanium and germanium-silicon alloys were frequently successful. At this conference we present the results of several germanium growth experiments performed in pyrolytic boron nitride containers. To exert an influence on the pressure ratio above and below the melt we used closed-bottom and open-bottom containers. This resulted in mainly detached-grown single crystals with the closed-bottom crucibles and attached single crystals with the open-bottom tubes. Evidence of detached growth is obtained from the crystal surface with a combination of axial profilometer scans and optical and electron microscopy. Detailed investigations of the defect structure, which is the main focus of this presentation, have shown an improvement of the crystal quality in the detached-grown samples, with a strong reduction of the etch pit density by about two orders of magnitude.

  12. Performance comparison of nonlinear crystals for frequency doubling of an 894nm Cs vapor laser

    Science.gov (United States)

    Zhdanov, B. V.; Shaffer, M. K.; Lu, Y.; Naumann, B.; Genda, T.; Knize, R. J.

    2010-11-01

    An examination of the efficiencies of three commonly used nonlinear crystals (PPKTP, LBO, and BiBO) when generating second harmonic of a Cesium laser is presented. The experiment investigates both the intracavity and single pass second harmonic generation of 895 nm Cs laser light when operating in quasi-CW and in CW modes and pumped by several watts. A degradation of the conversion efficiencies for each crystal was observed when high fundamental powers or a high duty cycle of the pump were used. For a Cs laser operating at 894nm, PPKTP is found to be the optimal crystal for intracavity SHG in both pulsed and CW modes when operating at SHG powers of several watts. At higher powers, however, the increased absorption coefficient of PPKTP at 447nm, compared to that of BiBO or LBO, may become significant to where another crystal will be more appropriate for this application. Maximum blue light power obtained with PPKTP crystal was about 1.5W in CW mode and 2.5W in QCW.

  13. Comparison of ordered and disordered silicon nanowire arrays: experimental evidence of photonic crystal modes.

    Science.gov (United States)

    Dhindsa, Navneet; Saini, Simarjeet S

    2016-05-01

    We experimentally compared the reflectance between ordered and disordered silicon nanowires to observe the evidence of photonic crystal modes. For similar diameters, the resonance peaks for the ordered nanowires at a spacing of 400 nm was at a shorter wavelength than the disordered nanowires, consistent to the excitation of photonic crystal modes. Furthermore, the resonant wavelength didn't shift while changing the density of the disordered nanowires, whereas there was a significant shift observed in the ordered ones. At an ordered spacing of 800 nm, the resonance wavelength approached that of the disordered structures, indicating that the ordered structures were starting to behave like individual waveguides. To our knowledge, this is the first direct experimental observation of photonic crystal modes in vertical periodic silicon nanowire arrays. PMID:27128070

  14. Comparison of surface and bulk crystallization of the amorphous Fe70Co10B20 alloy

    International Nuclear Information System (INIS)

    The effects of surface and bulk crystallization of the amorphous Fe70Co10B22 alloy are investigated by the aid of optical microscopy, scanning electron microscopy, and Moessbauer spectroscopy after annealings detecting γ-radiation and conversion electrons. The chemical composition of the amorphous matrix and of crystalline particles are determined by energy and wave dispersive analyses of X-rays. Measurements show that eutectic particles of crystallizing phases are observed in the bulk. Besides the non-uniformly distributed eutectic crystallites, an appreciable amount of α-Fe-Co phase is present at the surface of the sample

  15. Comparison of tunable lasers based on diode pumped Tm-doped crystals

    Science.gov (United States)

    Šulc, Jan; Jelínková, Helena; Koranda, Petr; Černý, Pavel; Jabczyński, Jan K.; Żendzian, Waldemar; Kwiatkowski, Jacek; Urata, Yoshiharu; Higuchi, Mikio

    2008-12-01

    We report on continuously tunable operation of a diode pumped lasers based on Tm-doped materials, emitting in the 1.8 - 2.μ1 m spectral band. In our study we compare results obtained with three various single crystals doped by Tm3+ ions: Yttrium Aluminum perovskite YAP (YAlO3), Gadolinium orthovanadate GdVO4, and Yttrium Lithium Fluoride YLF (YLiF4). Following samples were available: the 3mm long a-cut crystal rod of Tm:YAP with 4% at. Tm/Y (diameter 3 mm); the 8mm long b-cut crystal rod of Tm:YLF with 3.5% at. Tm/Y (diameter 3 mm); the 2.7mm long a-cut crystal block of Tm:GdVO4 with 2% at. Tm/Gd (crystal face 5×3 mm). For active medium pumping, the laser diode radiation was used. Because the tested samples differs significantly in absorption spectra, two fibre-coupled (core diameter 400 µm) temperature-tuned laser diodes were used: first operating at wavelength 793nm was used for Tm:YAP and Tm:YLF; the second operating at wavelength 802nm was used for Tm:GdVO4. In both cases, the continuous power up to 20W was available for pumping. The diode radiation was focused into the active crystal by two achromatic doublet lenses with the focal length f = 75 mm. The measured radius of pumping beam focus inside the crystal was 260 µm. The longitudinally diode pumped crystals were tested in linear, 80mm long, hemispherical laser cavity. The curved (radius 150mm) output coupler reflectivity was ~ 97 % in range from 1.8 up to 2.1 μm. The pumping flat mirror had maximal reflectivity in this range and it had high transmission around 0.8 μm. A 1.5mm thick birefringent plate made from quartz (Lyot filter) inserted under a Brewster's angle was used as a tuning element. This plate was placed inside the resonator between the crystal and the output coupler. Using Tm:YAP crystal, the maximal output power of 2.8W in this set-up was obtained. The laser could be tuned from 1865nm up to 2036nm with a maximum at 1985 nm. Laser based on Tm:YLF crystal was tunable from 1835nm up to

  16. Comparison of measured and computed phase functions of individual tropospheric ice crystals

    Science.gov (United States)

    Stegmann, Patrick G.; Tropea, Cameron; Järvinen, Emma; Schnaiter, Martin

    2016-07-01

    Airplanes passing the incuda (lat. anvils) regions of tropical cumulonimbi-clouds are at risk of suffering an engine power-loss event and engine damage due to ice ingestion (Mason et al., 2006 [1]). Research in this field relies on optical measurement methods to characterize ice crystals; however the design and implementation of such methods presently suffer from the lack of reliable and efficient means of predicting the light scattering from ice crystals. The nascent discipline of direct measurement of phase functions of ice crystals in conjunction with particle imaging and forward modelling through geometrical optics derivative- and Transition matrix-codes for the first time allow us to obtain a deeper understanding of the optical properties of real tropospheric ice crystals. In this manuscript, a sample phase function obtained via the Particle Habit Imaging and Polar Scattering (PHIPS) probe during a measurement campaign in flight over Brazil will be compared to three different light scattering codes. This includes a newly developed first order geometrical optics code taking into account the influence of the Gaussian beam illumination used in the PHIPS device, as well as the reference ray tracing code of Macke and the T-matrix code of Kahnert.

  17. Comparison of Modeled and Measured Performance of GSO Crystal as Gamma Detector

    CERN Document Server

    Parno, D S; Mamyan, V; Benmokhtar, F; Camsonne, A; Franklin, G B; Paschke, K; Quinn, B

    2012-01-01

    We have modeled, tested, and installed a large, cerium-activated Gd2SiO5 crystal scintillator for use as a detector of gamma rays up to 600 MeV. We present the measured detector response to two types of incident photons: nearly monochromatic photons up to 40 MeV, and photons from a continuous Compton backscattering spectrum up to 600 MeV. Our GEANT4 simulations reproduce the measured spectra well.

  18. Comparison of Classic Sweat Test and Crystallization Test in Diagnosis of Cystic Fibrosis

    OpenAIRE

    Fatemeh Farahmand; Nooshin Sadjadei; Mohammad-Taghi Haghi-Ashtiani; Vajiheh Modaresi; Nima Rezaei; Bahar Pakseresht

    2012-01-01

    Objective: Sweat chloride measurement is considered a standard diagnostic tool for cystic fibrosis (CF). This study was performed to compare sweat chloride values obtained by quantitative pilocarpine iontophoresis (classic test) with sweat crystallization detected by direct observation of a drop of perspiration under light microscopy in patients with and without CF.Methods: The tests using both techniques were performed simultaneously in patients with and without CF. Cutoff values of ≥60 mmol...

  19. Bandwidth comparison of photonic crystal fibers and conventional single mode fibers

    DEFF Research Database (Denmark)

    Nielsen, Martin Dybendal; Folkenberg, Jacob Riis; Mortensen, Niels Asger;

    2004-01-01

    We experimentally compare the optical bandwidth of a conventional single-mode fiber (SMF) with 3 different photonic crystal fibers (PCF) all optimized for visible applications. The spectral attenuation, single-turn bend loss, and mode-field diameters (MFD) are measured and the PCF is found to have...... a significantly larger bandwidth than the SMF for an identical MFD. It is shown how this advantage can be utilized for realizing a larger MFD for the PCF while maintaining a bending resistant fiber....

  20. Comparison of Cyclooxygenase-1 Crystal Structures: Cross-Talk between Monomers Comprising Cyclooxygenase-1 Homodimers

    Energy Technology Data Exchange (ETDEWEB)

    Sidhu, Ranjinder S.; Lee, Jullia Y.; Yuan, Chong; Smith, William L. (Michigan)

    2010-11-01

    Prostaglandin endoperoxide H synthases (PGHSs)-1 and -2 (also called cyclooxygenases (COXs)-1 and -2) catalyze the committed step in prostaglandin biosynthesis. Both isoforms are targets of nonsteroidal antiinflammatory drugs (NSAIDs). PGHSs are homodimers that exhibit half-of-sites COX activity; moreover, some NSAIDs cause enzyme inhibition by binding only one monomer. To learn more about the cross-talk that must be occurring between the monomers comprising each PGHS-1 dimer, we analyzed structures of PGHS-1 crystallized under five different conditions including in the absence of any tightly binding ligand and in the presence of nonspecific NSAIDs and of a COX-2 inhibitor. When crystallized with substoichiometric amounts of an NSAID, both monomers are often fully occupied with inhibitor; thus, the enzyme prefers to crystallize in a fully occupied form. In comparing the five structures, we only observe changes in the positions of residues 123-129 and residues 510-515. In cases where one monomer is fully occupied with an NSAID and the partner monomer is incompletely occupied, an alternate conformation of the loop involving residues 123-129 is seen in the partially occupied monomer. We propose, on the basis of this observation and previous cross-linking studies, that cross-talk between monomers involves this mobile 123-129 loop, which is located at the dimer interface. In ovine PGHS-1 crystallized in the absence of an NSAID, there is an alternative route for substrate entry into the COX site different than the well-known route through the membrane binding domain.

  1. Comparison of Lithium Gadolinium Borate Crystal Shards in Scintillating and Nonscintillating Plastic Matrices

    CERN Document Server

    Kazkaz, Kareem; Pedretti, Marisa

    2011-01-01

    We present a method for detecting neutrons using scintillating lithium gadolinium borate crystal shards in a plastic matrix while maintaining high gamma rejection. We have procured two cylindrical detectors, 5"\\times5", containing 1% crystal by mass. Crystal shards have a typical dimension of 1 mm. One detector was made with scintillating plastic, and one with nonscintillating plastic. Pulse shape analysis was used to reject gamma ray backgrounds. The scintillating detector was measured to have an intrinsic fast fission neutron efficiency of 0.4% and a gamma sensitivity of less than 2.3 \\times 10-9, while the nonscintillating detector had a neutron efficiency of 0.7% and gamma sensitivity of (4.75\\pm3.94)\\times10-9. We determine that increasing the neutron detection efficiency by a factor of 2 will make the detector competitive with moderated 3He tubes, and we discuss several simple and straightforward methods for obtaining or surpassing such an improvement. We end with a discussion of possible applications, ...

  2. Self-Consistent Theory of Elastic Properties of Strongly Anharmonic Crystals I:. General Treatment and Comparison with Computer Simulations and Experiment for Fcc Crystals

    Science.gov (United States)

    Zubov, V. I.; Sanchez, J. F.; Tretiakov, N. P.; Yusef, A. E.

    Based on the correlative method of an unsymmetrized self-consistent field,16-23 we have derived expressions for elastic constant tensors of strongly anharmonic crystals of cubic symmetry. Each isothermal elastic constant consists of four terms. The first one is the zeroth approximation containing the main anharmonicity (up to the fourth order). The second term is the quantum correction. It is important at temperatures below the De-bye characteristic temperature. Finally, the third and fourth terms are the perturbation theory corrections which take into account the influence of the correlations in atomic displacements from the lattice points and that of the high-order anharmonicity respectively. These corrections appear to be small up to the melting temperatures. It is sufficient for a personal computer to perform all our calculations with just a little computer time. A comparison with certain Monte Carlo simulations and with experimental data for Ar and Kr is made. For the most part, our results are between. The quasi-harmonic approximation fails at high temperatures, confirming once again the crucial role of strong anharmonicity.

  3. The X'tal cube PET detector with a monolithic crystal processed by the 3D sub-surface laser engraving technique: Performance comparison with glued crystal elements

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Eiji, E-mail: rush@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Hirano, Yoshiyuki; Tashima, Hideaki; Inadama, Naoko; Nishikido, Fumihiko [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Moriya, Takahiro; Omura, Tomohide; Watanabe, Mitsuo [Hamamatsu Photonics K.K., 5000 Hirakuchi, Hamakita-ku, Hamamatsu, Shizuoka 434-8601 (Japan); Murayama, Hideo; Yamaya, Taiga [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan)

    2013-09-21

    The X'tal cube is a depth-of-interaction (DOI)-PET detector which is aimed at obtaining isotropic resolution by effective readout of scintillation photons from six sides of the crystal block. The X'tal cube is composed of a 3D crystal block with isotropic segments. Each face of the 3D crystal block is covered with a 4×4 array of multi-pixel photon counters (MPPCs). Previously, in order to fabricate the 3D crystal block efficiently and precisely, we applied a sub-surface laser engraving technique to a monolithic crystal block instead of gluing segmented small crystals. A dense arrangement of multiple micro-cracks carved by the laser beam works efficiently as a scattering wall for the scintillation photons. The X'tal cube with the laser-processed block showed excellent performance with respect to crystal identification and energy resolution. In this work, for characteristics comparison between the laser-processed block and the conventional segmented array block, we made the laser-processed block and two types of segmented array blocks, one with air gaps and the other with glued segmented small crystals. All crystal blocks had 3D grids of 2 mm pitch. The 4×4 MPPC arrays were optically coupled to each surface of the crystal block. When performance was evaluated using a uniform irradiation of 511 keV, we found that the X'tal cubes with the laser-processed block could easily achieve 2 mm{sup 3} uniform crystal identification. Also, the average energy resolution of each 3D grid was 11.1±0.7%. On the other hand, the glued segmented array block had a pinched distribution and crystals could not be separated clearly. The segmented array block with air gaps had satisfactory crystal identification performance; however, the laser-processed block had higher crystal identification performance. Also, the energy resolution of the laser-processed block was better than for the segmented array blocks. In summary, we found the laser-processed X'tal cube had

  4. Comparison of the history effects in magnetization in weakly pinned crystals of high Tc and low Tc superconductors

    International Nuclear Information System (INIS)

    A comparison of the history effects in weakly pinned single crystals of a high Tc YBa2Cu3O7-δ (for H parallel c) and a low Tc Ca3Rh4Sn13, which show anomalous variations in critical current density Jc(H), is presented via the tracings of the minor magnetization hysteresis loops using a vibrating sample magnetometer. The sample histories focussed are: (i) the field cooled (FC), (ii) the zero field cooled (ZFC) and (iii) an isothermal reversal of field from the normal state. An understanding of the results in terms of the modulation in the plastic deformation of the elastic vortex solid and supercooling across the order-disorder transitions is sought. (author)

  5. A Comparison of Early Maladaptive Schemas in Crystal Addicted Individuals and Normal Individuals

    Directory of Open Access Journals (Sweden)

    Zahra Asadi

    2011-02-01

    Full Text Available Objective: The aim of present research was to compare early maladaptive schemas in crystal addicted individuals and normal individuals. Method: In this ex post facto research, two groups of subjects (normal adolescent=30 and addicted adolescent=30 were selected via cluster sampling and convenience sampling respectively. Yang early maladaptive schemas questionnaire were conducted, then data were analyzed using multiple analysis of variance. Results: The results revealed that there was significant difference between both groups in early maladaptive schemas. Conclusion: The findings provided empirical support for the proposition that early maladaptive schemas may influence on tendency of adolescent toward substance abuse.

  6. Numerical comparison between conventional dispersion compensating fibers and photonic crystal fibers as lumped Raman amplifiers.

    Science.gov (United States)

    Castellani, C E S; Cani, S P N; Segatto, M E V; Pontes, M J; Romero, M A

    2009-12-01

    In this paper we discuss the use of photonic crystal fibers (PCFs) as discrete devices for simultaneous wideband dispersion compensation and Raman amplification. The performance of the PCFs in terms of gain, ripple, optical signal-to-noise ratio (OSNR) and required fiber length for complete dispersion compensation is compared with conventional dispersion compensating fibers (DCFs). The main goal is to determine the minimum PCF loss beyond which its performance surpasses a state-of-the-art DCF and justifies practical use in telecommunication systems. PMID:20052245

  7. Comparison of modeled and measured performance of a GSO crystal as gamma detector

    Science.gov (United States)

    Parno, D. S.; Friend, M.; Mamyan, V.; Benmokhtar, F.; Camsonne, A.; Franklin, G. B.; Paschke, K.; Quinn, B.

    2013-11-01

    We have modeled, tested, and installed a large, cerium-activated Gd2SiO5 crystal scintillator for use as a detector of gamma rays. We present the measured detector response to two types of incident photons: nearly monochromatic photons up to 40 MeV, and photons from a continuous Compton backscattering spectrum up to 200 MeV. Our GEANT4 simulations, developed to determine the analyzing power of the Compton polarimeter in Hall A of Jefferson Lab, reproduce the measured spectra well.

  8. Comparison of modeled and measured performance of a GSO crystal as gamma detector

    International Nuclear Information System (INIS)

    We have modeled, tested, and installed a large, cerium-activated Gd2SiO5 crystal scintillator for use as a detector of gamma rays. We present the measured detector response to two types of incident photons: nearly monochromatic photons up to 40 MeV, and photons from a continuous Compton backscattering spectrum up to 200 MeV. Our GEANT4 simulations, developed to determine the analyzing power of the Compton polarimeter in Hall A of Jefferson Lab, reproduce the measured spectra well

  9. Comparison of modeled and measured performance of a GSO crystal as gamma detector

    Energy Technology Data Exchange (ETDEWEB)

    Parno, Diana Syemour [Carnegie Mellon U.; Friend, Megan Lynn [Carnegie Mellon U.; Mamyan, Vahe [Virginia U.; Benmokhtar, Fatiha [Duquesne U.; Camsonne, Alexandre [JLAB; Franklin, Gregg B. [Carnegie Mellon U.; Paschke, Kent D. [Virginia U.; Quinn, Brian Patrick [Carnegie Mellon U.

    2013-11-01

    We have modeled, tested, and installed a large, cerium-activated Gd{sub 2}SiO{sub 5} crystal scintillator for use as a detector of gamma rays. We present the measured detector response to two types of incident photons: nearly monochromatic photons up to 40 MeV, and photons from a continuous Compton backscattering spectrum up to 200 MeV. Our GEANT4 simulations, developed to determine the analyzing power of the Compton polarimeter in Hall A of Jefferson Lab, reproduce the measured spectra well.

  10. Comparison of modeled and measured performance of a GSO crystal as gamma detector

    Energy Technology Data Exchange (ETDEWEB)

    Parno, D.S., E-mail: dparno@uw.edu [Carnegie Mellon University, Department of Physics, Pittsburgh, PA 15213 (United States); University of Washington, Center for Experimental Nuclear Physics and Astrophysics and Department of Physics, Seattle, WA 98195 (United States); Friend, M. [Carnegie Mellon University, Department of Physics, Pittsburgh, PA 15213 (United States); High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki (Japan); Mamyan, V.; Benmokhtar, F. [Carnegie Mellon University, Department of Physics, Pittsburgh, PA 15213 (United States); Camsonne, A. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Franklin, G.B. [Carnegie Mellon University, Department of Physics, Pittsburgh, PA 15213 (United States); Paschke, K. [University of Virginia, Department of Physics, Charlottesville, VA 22904 (United States); Quinn, B. [Carnegie Mellon University, Department of Physics, Pittsburgh, PA 15213 (United States)

    2013-11-11

    We have modeled, tested, and installed a large, cerium-activated Gd{sub 2}SiO{sub 5} crystal scintillator for use as a detector of gamma rays. We present the measured detector response to two types of incident photons: nearly monochromatic photons up to 40 MeV, and photons from a continuous Compton backscattering spectrum up to 200 MeV. Our GEANT4 simulations, developed to determine the analyzing power of the Compton polarimeter in Hall A of Jefferson Lab, reproduce the measured spectra well.

  11. Comparison of crystal and solution hemoglobin binding of selected antigelling agents and allosteric modifiers

    International Nuclear Information System (INIS)

    This paper details comprehensive binding studies (solution and X-ray) of human hemoglobin A with a group of halogenated carboxylic acids that were investigated as potential antisickling agents. It is, to our knowledge, the first study to compare solution and crystal binding for a series of compounds under similar high-salt conditions used for cocrystallization. The compounds include [(3,4-dichlorobenzyl)oxy]acetic acid, [(p-bromobenzyl)oxy]acetic acid, clofibric acid, and bezafibrate. The location and stereochemistry of binding sites have been established by X-ray crystallography, while the number of binding sites and affinity constants were measured by using equilibrium dialysis. The observed crystal structures are consistent with the binding observed in solution and that the number of binding sites is independent of salt concentration, while the binding constant increases with increasing salt concentration. The studies also reveal that relatively small changes in the chemical structure of a drug molecule can result in entirely different binding sites on the protein. Moreover, the X-ray studies provide a possible explanation for the multiplicity in function exhibited by these compounds as allosteric modulators and/or antisickling agents. Finally, the studies indicate that these compounds bind differently to the R and T states of hemoglobin, and observation of special significance to the original design of these agents

  12. Comparison of crystal and solution hemoglobin binding of selected antigelling agents and allosteric modifiers

    Energy Technology Data Exchange (ETDEWEB)

    Mehanna, A.S.; Abraham, D.J. (Virginia Commonwealth Univ., Richmond (USA))

    1990-04-24

    This paper details comprehensive binding studies (solution and X-ray) of human hemoglobin A with a group of halogenated carboxylic acids that were investigated as potential antisickling agents. It is, to our knowledge, the first study to compare solution and crystal binding for a series of compounds under similar high-salt conditions used for cocrystallization. The compounds include ((3,4-dichlorobenzyl)oxy)acetic acid, ((p-bromobenzyl)oxy)acetic acid, clofibric acid, and bezafibrate. The location and stereochemistry of binding sites have been established by X-ray crystallography, while the number of binding sites and affinity constants were measured by using equilibrium dialysis. The observed crystal structures are consistent with the binding observed in solution and that the number of binding sites is independent of salt concentration, while the binding constant increases with increasing salt concentration. The studies also reveal that relatively small changes in the chemical structure of a drug molecule can result in entirely different binding sites on the protein. Moreover, the X-ray studies provide a possible explanation for the multiplicity in function exhibited by these compounds as allosteric modulators and/or antisickling agents. Finally, the studies indicate that these compounds bind differently to the R and T states of hemoglobin, and observation of special significance to the original design of these agents.

  13. The Effect of Single Crystal Elastic and Plastic Anisotropy on Strain Heterogeneity: Comparison of Olivine to Other Common Minerals

    Science.gov (United States)

    Cline, C. J., II; Burnley, P. C.

    2013-12-01

    In order to extrapolate the rheological behavior of polycrystalline earth materials to conditions and timescales that are unachievable in a laboratory setting, some sort of model is required. Numerical models are particularly appealing for this task but for these models to provide a sound platform for extrapolation they must be based on a complete understanding of all deformation mechanics that are operating in the real material. In a simplified description these mechanics can be thought of as having three components 1) the individual grains, 2) the grain boundaries and 3) the macroscopic aggregate response, which can be thought of as the interaction of the other two components within the polycrystal. Traditionally, the aggregate response is thought to represent the summed or average behavior of all individual grains deforming under the influence of the macroscopic stress tensor but; recent work within our lab using finite element models (FEM) has shown that local stress fields within the aggregate are not representative of the macroscopic stress tensor and can vary in both direction and magnitude. These variations in the stress tensor produce a pattern similar to force chains that are observed in deformation experiments on granular materials; and appear to be a direct consequence of stress percolation which is controlled by the anisotropy of the elastic and plastic strengths of the individual grains. To test this hypothesis we will conduct a suite of deformation experiments utilizing multiple monomineralic polycrystals that have a range of single crystal anisotropies. In order to infer the direction of stress acting on each grain and reconstruct the total modulation of stress direction throughout the sample, we have chosen materials that form microstructures that are sensitive to stress direction, such as deformation twins and kink bands. This experimental technique will allow for a direct comparison between the single crystal anisotropy of a material and the

  14. Comparison of CSD-YBCO growth on different single crystal substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kunert, J; Baecker, M; Falter, M; Schroeder-Obst, D [Trithor GmbH, Heisenbergstr. 16, D-53359 Rheinbach (Germany); University of Applied Sciences Bonn-Rhein-Sieg, von Liebig Strasse 20 D-53359 Rheinbach (Germany)], E-mail: Jan.Kunert@Trithor.de

    2008-02-01

    2G HTS Coated Conductors properties can be improved by comparing different raw materials, precursor production routes and coating and annealing conditions. To suppress the influence of varying substrate tapes and buffer layer qualities on the HTS layers, a standard substrate is needed to improve the Jc values. In this work various pure single crystal substrates (SrTiO{sub 3} [STO], (LaAlO{sub 3}){sub 0.3}(Sr{sub 2}AlTaO{sub 6}){sub 0.7} [LSAT], LaAlO{sub 3} [LAO], NdGaO{sub 3} [NdGaO]) are investigated to find the material which is best in terms of price, texture and morphological layout and instantaneous availability. YBCO films deposited onto these substrates via chemical solution deposition (CSD) are analysed using XRD texture analysis, surface morphology analysis (high resolution AFM) and inductive measurement of the critical current density.

  15. Comparison of CSD-YBCO growth on different single crystal substrates

    International Nuclear Information System (INIS)

    2G HTS Coated Conductors properties can be improved by comparing different raw materials, precursor production routes and coating and annealing conditions. To suppress the influence of varying substrate tapes and buffer layer qualities on the HTS layers, a standard substrate is needed to improve the Jc values. In this work various pure single crystal substrates (SrTiO3 [STO], (LaAlO3)0.3(Sr2AlTaO6)0.7 [LSAT], LaAlO3 [LAO], NdGaO3 [NdGaO]) are investigated to find the material which is best in terms of price, texture and morphological layout and instantaneous availability. YBCO films deposited onto these substrates via chemical solution deposition (CSD) are analysed using XRD texture analysis, surface morphology analysis (high resolution AFM) and inductive measurement of the critical current density

  16. Comparison between two types of photonic-crystal cavities for single-photon emitters

    International Nuclear Information System (INIS)

    The properties of photonic-crystal (PhC) cavity modes are investigated for applications in single-photon emitters. Hexagonal-lattice PhC H1 and L3 cavities are fabricated in a GaAs slab containing InAs quantum dots. The cavity modes are characterized by polarization-dependent micro-photoluminescence measurements. Split and nearly degenerate dipole modes in H1 cavities are demonstrated in the same batch of samples, and a single L3 cavity mode with specific polarization is clearly observed. The results reveal that the L3 PhC cavity exhibits fairly excellent performance even with remarkable distortion and is favorable for single-photon emitters. Finite-difference time-domain simulations show that the verticality of the air-hole sidewall has a significant influence on the properties of PhC cavity modes

  17. Comparison of silicon photonic crystal resonator designs for optical trapping of nanomaterials

    International Nuclear Information System (INIS)

    The use of silicon photonic devices for optical manipulation has recently enabled the direct handling of objects like nucleic acids and nanoparticles that are much smaller than could previously be trapped using traditional laser tweezers. The ability to manipulate even smaller matter however requires the development of photonic structures with even stronger trapping potentials. In this work we investigate theoretically several photonic crystal resonator designs and characterize the achievable trapping stiffness and trapping potential depth (sometimes referred to as the trapping stability). Two effects are shown to increase these trapping parameters: field enhancement in the resonator and strong field containment. We find trapping stiffness as high as 22.3 pN nm-1 for 100 nm polystyrene beads as well as potential depth of 51 000 kBT at T = 300 K, for one Watt of power input to the bus waveguide. Under the same conditions for 70 nm polystyrene beads, we find a stiffness of 69 pN nm-1 and a potential depth of 177 000 kBT. Our calculations suggest that with input power of 10 mW we could trap particles as small as 7.7 nm diameter with a trapping depth of 500 kBT. We expect these traps to eventually enable the manipulation of small matter such as single proteins, carbon nanotubes and metallic nanoparticles.

  18. Effect of different struvite crystallization methods on gaseous emission and the comprehensive comparison during the composting.

    Science.gov (United States)

    Jiang, Tao; Ma, Xuguang; Yang, Juan; Tang, Qiong; Yi, Zhigang; Chen, Maoxia; Li, Guoxue

    2016-10-01

    This study compared 4 different struvite crystallization process (SCP) during the composting of pig feces. Four combinations of magnesium and phosphate salts (H3PO4+MgO (PMO), KH2PO4+MgSO4 (KPM), Ca(H2PO4)2+MgSO4 (CaPM), H3PO4+MgSO4 (PMS)) were assessed and were also compared to a control group (CK) without additives. The magnesium and phosphate salts were all supplemented at a level equivalent to 15% of the initial nitrogen content on a molar basis. The SCP significantly reduced NH3 emission by 50.7-81.8%, but not the N2O. Although PMS group had the lowest NH3 emission rate, the PMO treatment had the highest struvite content in the end product. The addition of sulphate decreased CH4 emission by 60.8-74.6%. The CaPM treatment significantly decreased NH3 (59.2%) and CH4 (64.9%) emission and yielded compost that was completely matured. Due to its effective performance and low cost, the CaPM was suggested to be used in practice. PMID:26927235

  19. Comparison of liquid crystal versus cathode ray tube display for the detection of simulated chest lesions

    International Nuclear Information System (INIS)

    The purpose of the study was to compare the detection performance of a cathode ray tube (CRT) monitor versus a liquid crystal display (LCD) monitor for simulated subtle pulmonary lesions. Ten templates containing simulated lung lesions were superimposed on an anthropomorphic chest phantom. Posteroanterior radiographs were obtained using flat panel technology and were displayed on a CRT and an LCD monitor. Image processing and reading conditions were equivalent for both softcopy displays. Five observers assessed lesion detectability using receiver-operating characteristic (ROC) methodology. A multivariate test (Pillai trace) was used to test the significance of differences (P<0.05). The multivariate test revealed significantly different detection rates for the lesion types, but no significant difference between the two display modes. Detection performance for both monitors was higher for nodules and micro-nodules and lower for lines and patchy opacities. Analysis of lesion subgroups according to their location in lucent/obscured lung areas was also not statistically significant. Under ideal reading conditions, CRT and LCD displays perform equivalently for the detection of simulated subtle pulmonary lesions. (orig.)

  20. Superposition of two tRNASer acceptor stem crystal structures: Comparison of structure, ligands and hydration

    International Nuclear Information System (INIS)

    We solved the X-ray structures of two Escherichia coli tRNASer acceptor stem microhelices. As both tRNAs are aminoacylated by the same seryl-tRNA-synthetase, we performed a comparative structure analysis of both duplexes to investigate the helical conformation, the hydration patterns and magnesium binding sites. It is well accepted, that the hydration of RNA plays an important role in RNA-protein interactions and that the extensive solvent content of the minor groove has a special function in RNA. The detailed comparison of both tRNASer microhelices provides insights into the structural arrangement of the isoacceptor tRNA aminoacyl stems with respect to the surrounding water molecules and may eventually help us to understand their biological function at atomic resolution.

  1. A comparison of VRML and animation of rotation for teaching 3-dimensional crystal lattice structures

    Science.gov (United States)

    Sauls, Barbara Lynn

    Chemistry students often have difficulty visualizing abstract concepts of molecules and atoms, which may lead to misconceptions. The three-dimensionality of these structures presents a challenge to educators. Typical methods of teaching include text with two-dimensional graphics and structural models. Improved methods to allow visualization of 3D structures may improve learning of these concepts. This research compared the use of Virtual Reality Modeling Language (VRML) and animation of rotation for teaching three-dimensional structures. VRML allows full control of objects by altering angle, size, rotation, and provides the ability to zoom into and through objects. Animations may only be stopped, restarted and replayed. A web-based lesson teaching basic concepts of crystals, which requires comprehension of their three-dimensional structure was given to 100 freshmen chemistry students. Students were stratified by gender then randomly to one of two lessons, which were identical except for the multimedia method used to show the lattices and unit cells. One method required exploration of the structures using VRML, the other provided animations of the same structures rotating. The students worked through an examination as the lesson progressed. A Welch t' test was used to compare differences between groups. No significant difference in mean achievement was found between the two methods, between genders, or within gender. There was no significant difference in mean total SAT in the animation and VRML group. Total time on task had no significant difference nor did enjoyment of the lesson. Students, however, spent 14% less time maneuvering VRML structures than viewing the animations of rotation. Neither method proved superior for presenting three-dimensional information. The students spent less time maneuvering the VRML structures with no difference in mean score so the use of VRML may be more efficient. The investigator noted some manipulation difficulties using VRML to

  2. Modeling Nucleation, Growth, and Ostwald Ripening in Crystallization Processes: A Comparison between Population Balance and Kinetic Rate Equation

    OpenAIRE

    Vetter, Thomas; Iggland, Martin; Ochsenbein, David R; Haenseler, Flurin S; Mazzotti, Marco

    2013-01-01

    In this work, we investigate a comprehensive model describing nucleation, growth and Ostwald ripening based on the kinetic rate equation and compare it to commonly used population balance equation models that either describe nucleation and crystal growth or crystal growth and Ostwald ripening. The kinetic rate equation gives a microscopic description of crystallization, i.e., the process is seen as an attachment and detachment of crystals of different sizes to and from each other, thereby cha...

  3. The crystal structure analysis of deuterated benzene and deuterated nitromethane by pulsed-neutron powder diffraction: a comparison with single crystal neutron diffraction analysis

    International Nuclear Information System (INIS)

    The results of time-of-flight neutron powder diffraction analyses at 4.2 K are compared with those from steady-state neutron single-crystal analyses at 15 K for deuterated benzene, C6D6, and deuteronitromethane, CD3NO2. (orig.)

  4. Suppression of Raman electron spin relaxation of radicals in crystals. Comparison of Cu2+ and free radical relaxation in triglycine sulfate and Tutton salt single crystals.

    Science.gov (United States)

    Hoffmann, S K; Goslar, J; Lijewski, S

    2011-08-31

    Electron spin-lattice relaxation was measured by the electron spin echo method in a broad temperature range above 4.2 K for Cu(2+) ions and free radicals produced by ionizing radiation in triglycine sulfate (TGS) and Tutton salt (NH4)(2)Zn(SO4)2 ⋅ 6H2O crystals. Localization of the paramagnetic centres in the crystal unit cells was determined from continuous wave electron paramagnetic resonance spectra. Various spin relaxation processes and mechanisms are outlined. Cu(2+) ions relax fast via two-phonon Raman processes in both crystals involving the whole phonon spectrum of the host lattice. This relaxation is slightly slower for TGS where Cu(2+) ions are in the interstitial position. The ordinary Raman processes do not contribute to the radical relaxation which relaxes via the local phonon mode. The local mode lies within the acoustic phonon band for radicals in TGS but within the optical phonon range in (NH4)(2)Zn(SO4)2 ⋅ 6H2O. In the latter the cross-relaxation was considered. A lack of phonons around the radical molecules suggested a local crystal amorphisation produced by x- or γ-rays. PMID:21841228

  5. Comments on: “Crystal growth and comparison of vibrational and thermal properties of semi-organic nonlinear optical materials”

    Indian Academy of Sciences (India)

    Srinivasan Bikshandarkoil R; Fernandes Royle

    2016-03-01

    In {\\it Pramana – J. Phys. } 75, 683 (2010), Gunasekaran et al reported that they have grown the nonlinear optical crystals, urea thiourea mercuric chloride (UTHC) and urea thiourea mercuric sulphate (UTHS).We argue that UTHC and UTHS are dubious crystals and are not what the authors propose.

  6. Comparison and characterization of efficient frequency doubling at 397.5 nm with PPKTP, LBO and BiBO crystals

    OpenAIRE

    WEN, Xin; Han, Yashuai; Wang, Junmin

    2016-01-01

    A continuous-wave Ti:sapphire laser at 795 nm is frequency doubled in a bow-tie type enhancement four-mirror ring cavity with LiB3O5 (LBO), BiB3O6 (BiBO), and periodically polled KTiOPO4 (PPKTP) crystals, respectively. The properties of 397.5 nm ultra-violet (UV) output power, beam quality, stability for these different nonlinear crystals are investigated and compared. For PPKTP crystal, the highest doubling efficiency of 58.1% is achieved from 191 mW of 795 nm mode-matched fundamental power ...

  7. A comparison of the magnetic properties of radiation damaged or Co implanted ZnO single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Werner, Z. [National Centre for Nuclear Research, Otwock (Poland); Gosk, J. [Faculty of Physics, Warsaw University, Warsaw (Poland); Faculty of Physics, Warsaw Technical University, Warsaw (Poland); Twardowski, A. [Faculty of Physics, Warsaw University, Warsaw (Poland); Barlak, M.; Pochrybniak, C. [National Centre for Nuclear Research, Otwock (Poland)

    2015-09-01

    Highlights: • Co implantation in ZnO single crystal introduces paramagnetic and ferromagnetic phases. • Electron and proton irradiations have no effect on crystal magnetic properties. • Co ions seem to stabilize the radiation defects. - Abstract: To elucidate the interaction between defects and transition metal impurities in creating magnetic properties in wide band-gap semiconductors, single crystals of ZnO were irradiated with high-energy electrons, protons and Co ions. Magnetization of samples was measured before and after room temperature irradiation. The measurements reveal that only Co implantation creates measurable magnetization, which is related to the simultaneous introduction of defects. Consequences of the experimental results are discussed.

  8. Comparison and characterization of efficient frequency doubling at 397.5 nm with PPKTP, LBO and BiBO crystals

    CERN Document Server

    Wen, Xin; Wang, Junmin

    2016-01-01

    A continuous-wave Ti:sapphire laser at 795 nm is frequency doubled in a bow-tie type enhancement four-mirror ring cavity with LiB3O5 (LBO), BiB3O6 (BiBO), and periodically polled KTiOPO4 (PPKTP) crystals, respectively. The properties of 397.5 nm ultra-violet (UV) output power, beam quality, stability for these different nonlinear crystals are investigated and compared. For PPKTP crystal, the highest doubling efficiency of 58.1% is achieved from 191 mW of 795 nm mode-matched fundamental power to 111 mW of 397.5 nm UV output. For LBO crystal, with 1.34 W of mode-matched 795 nm power, 770 mW of 397.5 nm UV output is achieved, implying a doubling efficiency of 57.4%. For BiBO crystal, with 323 mW of mode-matched 795 nm power, 116 mW of 397.5 nm UV output is achieved, leading to a doubling efficiency of 35.9%. The generated UV radiation has potential applications in the fields of quantum physics

  9. Comparison in internal strain sensitivity between polariscopy and Raman scattering spectroscopy in a (110)-oriented ZnTe single crystal

    International Nuclear Information System (INIS)

    We present the experimental fact that, in a (110)-oriented ZnTe single crystal, polariscopy is highly sensitive to the internal strain, comparing with Raman scattering spectroscopy. We utilized X-ray topography and X-ray diffraction analysis to thoroughly investigate the crystal structure that is intimately associated with the internal strain. The two X-ray structure analyses clarified that the misalignment from the [110] direction is formed in some regions. We obtained the following main result: The polariscopic analysis detects the internal strain formed by the misalignment, whereas the Raman scattering measurement is insensitive to the internal strain. We, therefore, conclude that polariscopy has the strain-detection sensitivity higher than the Raman scattering spectroscopy. We have confirmed that the polariscopic analysis can detect the internal strain less than 0.5% in the ZnTe crystal. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Asparagine and glutamine side-chain conformation in solution and crystal: A comparison for hen egg-white lysozyme using residual dipolar ouplings

    International Nuclear Information System (INIS)

    Experimental 15N-1H and 1H-1H residual dipolar couplings (RDCs) for the asparagine (Asn) and glutamine (Gln) side chains of hen egg-white lysozyme are measured and analysed in conjunction with 1N relaxation data, information about χ1 torsion angles in solution and molecular dynamics simulations. The RDCs are compared to values predicted from 16 high-resolution crystal structures. Two distinct groups of Asn and Gln side chains are identified. The first contains residues whose side chains show a fixed, relatively rigid, conformation in solution. For these residues there is good agreement between the experimental and predicted RDCs. This agreement improves when the experimental order parameter, S, is included in the calculation of the RDCs from the crystal structures. The comparison of the experimental RDCs with values calculated from the X-ray structures shows that the similarity between the oxygen and nitrogen electron densities is a limitation to the correct assignment of the Asn and Gln side-chain orientation in X-ray structures. In the majority of X-ray structures a 180 deg. rotation about χ2 or χ3, leading to the swapping of Nδε2 and Oδε1, is necessary for at least one Asn or Gln residue in order to achieve good agreement between experimental and predicted RDCs. The second group contains residues whose side chains do not adopt a single, well-defined, conformation in solution. These residues do not show a correlation between the experimental and predicted RDCs. In many cases the family of crystal structures shows a range of orientations for these side chains, but in others the crystal structures show a well-defined side-chain position. In the latter case, this is found to arise from crystallographic contacts and does not represent the behaviour of the side chain in solution

  11. Comparison of the Spectral Characteristics of Chromium-Containing Crystals of the Calcium Gallogermanate Type with Their Structural Features

    International Nuclear Information System (INIS)

    The molecular refractions and characteristics of the circular dichroism spectra of unactivated and chromiumactivated La3Ga5.5Ta0.5O14, La3Ga5.5Nb0.5O14, La3Ga5GeO14, La3Ga5SiO14, Sr3Ga2Ge4O14, and Ca3Ga2Ge4O14crystals are compared with their structural parameters. Correlations between the molecular refractions and the structural distortions responsible for the optical activity of crystals and correlations between the characteristics of circular dichroism bands of defects and chromium ions and the interatomic distances in polyhedra and their distortions are found. The calcium gallogermanate structures exhibit a unique correspondence between the electronic configuration of host ions and the local symmetry.

  12. Single crystal LaB6: a comparison with currently used thermionic cathodes for broad beam applications

    International Nuclear Information System (INIS)

    The use of single crystal LaB6 cathodes in microbeam applications has grown dramatically in the past few years, due to recognition of the high current density/low volatility characteristics of this material. We present here experimental results suggesting that advanced, single crystal LaB6 cathodes should also satisfy the requirements of broad beam applications, such as satellite-borne traveling wave tubes, where high current density, long lifetime and excellent stability and reproducibility are necessary. The most important parameters for cathode characterization are available emitted current density, material vaporization rate, lifetime and power consumption. Other important characteristics are activation procedure, resistance to poisoning by impurities, emission stability and emission uniformity across the cathode emitting surface. The current state of the art cathode type used in commercial devices is the impregnated dispenser cathode (IDC). The construction of such cathodes are outlined briefly, and their operating properties are discussed

  13. Comparison of two approaches to forced convection in crystal growth of II-VI compounds by THM

    OpenAIRE

    Bloedner, R. U.; Presia, M.; Gille, Peter

    1994-01-01

    Hg1 - xCdxTe and Cd1 - xZnxTe single crystals were grown by the tracwelling heater method (THM), applying two different techniques of artificially stirring the solution zone. Accelerated crucible rotation (ACRT) was used in a vertical growth arrangement and compared a technique with constant rotation around the horizontal axis of the ampoule. The dominant hydrodynamic mechanisms of noth methods are discribed by the rotating disc model and are suggested to be almost identical with respect to t...

  14. Effects of preexisting ice crystals on cirrus clouds and comparison between different ice nucleation parameterizations with the Community Atmosphere Model (CAM5

    Directory of Open Access Journals (Sweden)

    X. Shi

    2014-07-01

    Full Text Available In order to improve the treatment of ice nucleation in a more realistic manner in the Community Atmospheric Model version 5.3 (CAM5.3, the effects of preexisting ice crystals on ice nucleation in cirrus clouds are considered. In addition, by considering the in-cloud variability in ice saturation ratio, homogeneous nucleation takes place spatially only in a portion of cirrus cloud rather than in the whole area of cirrus cloud. With these improvements, the two unphysical limiters used in the representation of ice nucleation are removed. Compared to observations, the ice number concentrations and the probability distributions of ice number concentration are both improved with the updated treatment. The preexisting ice crystals significantly reduce ice number concentrations in cirrus clouds, especially at mid- to high latitudes in the upper troposphere (by a factor of ~10. Furthermore, the contribution of heterogeneous ice nucleation to cirrus ice crystal number increases considerably. Besides the default ice nucleation parameterization of Liu and Penner (2005, hereafter LP in CAM5.3, two other ice nucleation parameterizations of Barahona and Nenes (2009, hereafter BN and Kärcher et al. (2006, hereafter KL are implemented in CAM5.3 for the comparison. In-cloud ice crystal number concentration, percentage contribution from heterogeneous ice nucleation to total ice crystal number, and preexisting ice effects simulated by the three ice nucleation parameterizations have similar patterns in the simulations with present-day aerosol emissions. However, the change (present-day minus pre-industrial times in global annual mean column ice number concentration from the KL parameterization (3.24 × 106 m−2 is obviously less than that from the LP (8.46 × 106 m−2 and BN (5.62 × 106 m−2 parameterizations. As a result, experiment using the KL parameterization predicts a much smaller anthropogenic aerosol longwave indirect forcing (0.24 W m−2 than that

  15. A comparison of BCF-12 organic scintillators and Al2O3:C crystals for real-time medical dosimetry

    DEFF Research Database (Denmark)

    Beierholm, Anders Ravnsborg; Andersen, Claus Erik; Lindvold, Lars;

    2008-01-01

    Radioluminescence (RL) from aluminium oxide (Al2O3:C) crystals and organic scintillators such as the blue-emitting BCF-12 can be used for precise real-time dose rate measurements during radiation therapy of cancer patients. Attaching the dosimeters to thin light-guiding fiber cables enables in vivo...... can be circumvented for pulsed beams due to the long life-time of the main luminescence center. In contrast, chromatic removal seems to be the most effective method for organic scintillators, but is found to yield some experimental complexities. In this paper, we report on dose rate measurements using...

  16. Comparison of thermomagnetic history effects in weakly pinned single crystals of 3Rh4Sn13(R=Yb, Ca)

    Indian Academy of Sciences (India)

    S Sarkar; S Ramakrishnan; A K Grover; C V Tomy; G Balakrishnan; D McK Paul

    2002-05-01

    A comparative study of the thermomagnetic memory effects of c in two weakly pinned low c superconductors, Ca3Rh4Sn13 (CaRhSn) and Yb3Rh4Sn13 (YbRhSn), is presented. In both the systems, the peak effect (PE) phenomenon appears as an order–disorder transformation through stepwise amorphization of the flux line lattice (FLL). However, in CaRhSn, we can witness another disorder-driven transition (Bragg glass (BG) to a vortex glass (VG)) in a distinct manner as in a single crystal of high c YBa2Cu3O7- for $H||c$.

  17. Comparison of thermomagnetic history effects in weakly pinned single crystals of R3Rh4Sn13 (R = Yb, Ca)

    International Nuclear Information System (INIS)

    A comparative study of the thermomagnetic memory effects of Jc in two weakly pinned low Tc superconductors. Ca3Rh4Sn13 (CaRhSn) and Yb3Rh4Sn13 (YbRhSn), is presented. in both the systems, the peak effect (PE) phenomenon appears as an order-disorder transformation through stepwise amorphization of the flux line lattice (FLL). However, in CaRhSn, we can witness another disorder-driven transition (Bragg glass (BG) to a vortex glass (VG)) in a distinct manner as in a single crystal of high Tc YBa2Cu3O7-δ for H||c. (author)

  18. Crystal structure of anhydrous tripotassium citrate from laboratory X-ray powder diffraction data and DFT comparison.

    Science.gov (United States)

    Rammohan, Alagappa; Kaduk, James A

    2016-08-01

    The crystal structure of anhydrous tripotassium citrate, [K3(C6H5O7)] n , has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The three unique potassium cations are 6-, 8-, and 6-coordinate (all irregular). The [KO n ] coordination polyhedra share edges and corners to form a three-dimensional framework, with channels running parallel to the c axis. The only hydrogen bond is an intra-molecular one involving the hy-droxy group and the central carboxyl-ate group, with graph-set motif S(5). PMID:27536403

  19. Comparison of total experimental and theoretical absolute γ-ray detection efficiencies of a cylindrical NaI(Tl) crystal

    International Nuclear Information System (INIS)

    A new fit function has been developed to calculate theoretically the absolute gamma ray detection efficiencies (ηTh) of a cylindrical NaI(Tl) crystal, for calculating the absolute efficiency at any interesting gamma energy in the energy range between 10 and 1300 keV and distance between 0 and 8 cm. The total absolute gamma ray detection efficiencies have been calculated for five detectors, four are 2x2 and one is 3x 3 inches NaI(Tl) crystal at different distances. The absolute efficiency of the different detectors was calculated at the specific energy of the standard sources for each measuring distances. In this calculation, experimental (ηExp) and theoretical (ηTh) have been calculated. The uncertainties of efficiency calibration have been calculated also for quality control. Measurements were performed with calibrated point source. Gamma-ray energies under consideration were 0.356, 0.662, 1.17 and 1.33 MeV. The differences between (ηExp) and (ηTh) at these energies are 1.30E-06, 7.99E-05, 2.29E-04 and 2.42E-04 respectively. The results obtained on the basis of (ηExp) and (ηTh) seem to be in very good agreement

  20. Dynamics in liquid crystals

    International Nuclear Information System (INIS)

    Five types of reorientational motions for molecules in liquid crystals are discussed on the basis of a comparison of the neutron scattering and the dielectric relaxation methods. 18 refs., 7 figs., 2 tabs. (author)

  1. Asparagine and glutamine side-chain conformation in solution and crystal: A comparison for hen egg-white lysozyme using residual dipolar ouplings

    Energy Technology Data Exchange (ETDEWEB)

    Higman, Victoria A.; Boyd, Jonathan; Smith, Lorna J.; Redfield, Christina [University of Oxford, Oxford Centre for Molecular Sciences (United Kingdom)], E-mail: christina.redfield@bioch.ox.ac.uk

    2004-11-15

    Experimental {sup 15}N-{sup 1}H and {sup 1}H-{sup 1}H residual dipolar couplings (RDCs) for the asparagine (Asn) and glutamine (Gln) side chains of hen egg-white lysozyme are measured and analysed in conjunction with {sup 1}N relaxation data, information about {chi}{sup 1} torsion angles in solution and molecular dynamics simulations. The RDCs are compared to values predicted from 16 high-resolution crystal structures. Two distinct groups of Asn and Gln side chains are identified. The first contains residues whose side chains show a fixed, relatively rigid, conformation in solution. For these residues there is good agreement between the experimental and predicted RDCs. This agreement improves when the experimental order parameter, S, is included in the calculation of the RDCs from the crystal structures. The comparison of the experimental RDCs with values calculated from the X-ray structures shows that the similarity between the oxygen and nitrogen electron densities is a limitation to the correct assignment of the Asn and Gln side-chain orientation in X-ray structures. In the majority of X-ray structures a 180 deg. rotation about {chi}{sup 2} or {chi}{sup 3}, leading to the swapping of N{sup {delta}}{sup {epsilon}}{sup 2} and O{sup {delta}}{sup {epsilon}}{sup 1}, is necessary for at least one Asn or Gln residue in order to achieve good agreement between experimental and predicted RDCs. The second group contains residues whose side chains do not adopt a single, well-defined, conformation in solution. These residues do not show a correlation between the experimental and predicted RDCs. In many cases the family of crystal structures shows a range of orientations for these side chains, but in others the crystal structures show a well-defined side-chain position. In the latter case, this is found to arise from crystallographic contacts and does not represent the behaviour of the side chain in solution.

  2. A comparison between experiment and theory on few-quantum-dot nanolasing in a photonic-crystal cavity

    DEFF Research Database (Denmark)

    Liu, Jin; Ates, Serkan; Lorke, Michael;

    2013-01-01

    We present an experimental and theoretical study on the gain mechanism in a photonic-crystal-cavity nanolaser with embedded quantum dots. From time-resolved measurements at low excitation power we find that four excitons are coupled to the cavity. At high excitation power we observe a smooth low......-threshold transition from spontaneous emission to lasing. Before lasing emission sets in, however, the excitons are observed to saturate, and the gain required for lasing originates rather from multi-excitonic transitions, which give rise to a broad emission background. We compare the experiment to a model of quantum......-dot microcavity lasers and find that the number of excitons that must be included to fit the data largely exceeds the measured number, which shows that transitions involving the wetting layer can provide a surprisingly large contribution to the gain....

  3. Comparison of laser performance of electro-optic Q-switched Nd:YAG ceramic/single crystal laser

    Institute of Scientific and Technical Information of China (English)

    Jianghua Ji; Xiaolei Zhu; Chunyu Wang; Yongwei Feng; Qihong Lou

    2006-01-01

    @@ An electro-optic Q-switched Nd:YAG ceramic laser operating at kHz repetition rate was demonstrated.Thermal induced lens' focus of ceramic rod was measured and compensated by plano-convex cavity structure. Depolarization loss at different output powers was measured in Nd:YAG single crystal and ceramic lasers. High-energy high-beam-quality laser pulse output was obtained in both laser structures. Pulse energy of about 20 mJ and pulse width of less than 12 ns were achieved, and the average power reached 20 W. The divergence of output laser beam was less than 1.2 mrad, and the beam propagation factor M2was about 1.4.

  4. Comparison of Process of Diffusion of Interstitial Oxygen Atoms and Interstitial Hydrogen Molecules in Silicon and Germanium Crystals: Quantumchemical Simulation

    OpenAIRE

    Gusakov, Vasilii

    2006-01-01

    The theoretical analysis of the process of diffusion of interstitial oxygen atoms and hydrogen molecules in silicon and germanium crystals has been performed. The calculated values of the activation energy and pre-exponential factor for an interstitial oxygen atom Ea(Si) = 2.59 eV, Ea(Ge) = 2.05 eV, D(Si)= 0.28 cm2s-1, D(Ge)= 0.39 cm2s-1 and interstitial hydrogen molecule Ea(Si) = 0.79-0.83 eV, Ea(Ge) = 0.58-0.62 eV, D(Si)= 7.4 10(-4) cm2s-1, D(Ge)= 6.5 10(-4) cm2s-1 are in an excellent agree...

  5. Evaluation of a rapid dipstick (Crystal VC for the diagnosis of cholera in Zanzibar and a comparison with previous studies.

    Directory of Open Access Journals (Sweden)

    Benedikt Ley

    Full Text Available BACKGROUND: The gold standard for the diagnosis of cholera is stool culture, but this requires laboratory facilities and takes at least 24 hours. A rapid diagnostic test (RDT that can be used by minimally trained staff at treatment centers could potentially improve the reporting and management of cholera outbreaks. METHODS: We evaluated the Crystal VC™ RDT under field conditions in Zanzibar in 2009. Patients presenting to treatment centers with watery diarrhea provided a stool sample for rapid diagnostic testing. Results were compared to stool culture performed in a reference laboratory. We assessed the overall performance of the RDT and evaluated whether previous intake of antibiotics, intravenous fluids, location of testing, and skill level of the technician affected the RDT results. RESULTS: We included stool samples from 624 patients. Compared to culture, the overall sensitivity of the RDT was 93.1% (95%CI: 88.7 to 96.2%, specificity was 49.2% (95%CI: 44.3 to 54.1%, the positive predictive value was 47.0% (95%CI: 42.1 to 52.0% and the negative predictive value was 93.6% (95%CI: 89.6 to 96.5%. The overall false positivity rate was 50.8% (213/419; fieldworkers frequently misread very faint test lines as positive. CONCLUSION: The observed sensitivity of the Crystal VC RDT evaluated was similar compared to earlier versions, while specificity was poorer. The current version of the RDT could potentially be used as a screening tool in the field. Because of the high proportion of false positive results when field workers test stool specimens, positive results will need to be confirmed with stool culture.

  6. Nonlinear elastic effects in phase field crystal and amplitude equations: Comparison to ab initio simulations of bcc metals and graphene

    Science.gov (United States)

    Hüter, Claas; Friák, Martin; Weikamp, Marc; Neugebauer, Jörg; Goldenfeld, Nigel; Svendsen, Bob; Spatschek, Robert

    2016-06-01

    We investigate nonlinear elastic deformations in the phase field crystal model and derived amplitude equation formulations. Two sources of nonlinearity are found, one of them is based on geometric nonlinearity expressed through a finite strain tensor. This strain tensor is based on the inverse right Cauchy-Green deformation tensor and correctly describes the strain dependence of the stiffness for anisotropic and isotropic behavior. In isotropic one- and two-dimensional situations, the elastic energy can be expressed equivalently through the left deformation tensor. The predicted isotropic low-temperature nonlinear elastic effects are directly related to the Birch-Murnaghan equation of state with bulk modulus derivative K'=4 for bcc. A two-dimensional generalization suggests K2D '=5 . These predictions are in agreement with ab initio results for large strain bulk deformations of various bcc elements and graphene. Physical nonlinearity arises if the strain dependence of the density wave amplitudes is taken into account and leads to elastic weakening. For anisotropic deformation, the magnitudes of the amplitudes depend on their relative orientation to the applied strain.

  7. Crystal structures of a halophilic archaeal malate synthase from Haloferax volcanii and comparisons with isoforms A and G

    Directory of Open Access Journals (Sweden)

    Thomas Geoffrey C

    2011-05-01

    Full Text Available Abstract Background Malate synthase, one of the two enzymes unique to the glyoxylate cycle, is found in all three domains of life, and is crucial to the utilization of two-carbon compounds for net biosynthetic pathways such as gluconeogenesis. In addition to the main isoforms A and G, so named because of their differential expression in E. coli grown on either acetate or glycolate respectively, a third distinct isoform has been identified. These three isoforms differ considerably in size and sequence conservation. The A isoform (MSA comprises ~530 residues, the G isoform (MSG is ~730 residues, and this third isoform (MSH-halophilic is ~430 residues in length. Both isoforms A and G have been structurally characterized in detail, but no structures have been reported for the H isoform which has been found thus far only in members of the halophilic Archaea. Results We have solved the structure of a malate synthase H (MSH isoform member from Haloferax volcanii in complex with glyoxylate at 2.51 Å resolution, and also as a ternary complex with acetyl-coenzyme A and pyruvate at 1.95 Å. Like the A and G isoforms, MSH is based on a β8/α8 (TIM barrel. Unlike previously solved malate synthase structures which are all monomeric, this enzyme is found in the native state as a trimer/hexamer equilibrium. Compared to isoforms A and G, MSH displays deletion of an N-terminal domain and a smaller deletion at the C-terminus. The MSH active site is closely superimposable with those of MSA and MSG, with the ternary complex indicating a nucleophilic attack on pyruvate by the enolate intermediate of acetyl-coenzyme A. Conclusions The reported structures of MSH from Haloferax volcanii allow a detailed analysis and comparison with previously solved structures of isoforms A and G. These structural comparisons provide insight into evolutionary relationships among these isoforms, and also indicate that despite the size and sequence variation, and the truncated C

  8. Comparison of the electronic structure of anatase and rutile TiO2 single-crystal surfaces using resonant photoemission and x-ray absorption spectroscopy

    Science.gov (United States)

    Thomas, A. G.; Flavell, W. R.; Mallick, A. K.; Kumarasinghe, A. R.; Tsoutsou, D.; Khan, N.; Chatwin, C.; Rayner, S.; Smith, G. C.; Stockbauer, R. L.; Warren, S.; Johal, T. K.; Patel, S.; Holland, D.; Taleb, A.; Wiame, F.

    2007-01-01

    A comparison of the electronic structure of rutile (110), anatase (101), and anatase (001) single-crystal surfaces has been made using resonant photoemission and x-ray absorption spectroscopy. Under identical preparative conditions, the anatase (101) surface shows the lowest Ti3d and 4sp hybridization in the states close to the valence-band maximum of the three surfaces. It also shows the highest concentration of surface-oxygen vacancies. The effect on the electronic structure of modifying the surface preparative route and thus the concentration of surface-oxygen vacancies is examined. The σ -antibonding Ti3deg/O2p hybridization (probed by XAS) is reduced by the removal of surface-oxygen. Photoemission shows that as the number of surface-defects is increased, the O2p-Ti3dt2gπ -bonding interaction is disrupted. For the anatase (101) surface it is found that as the number of surface-oxygen vacancies is increased, the Ti3d and 4sp contributions at the valence-band maximum are reduced. We discuss the correlation between electronic structure and photocatalytic activity of the different polymorphs of TiO2 .

  9. A comparison of 95 MeV oxygen ions and 60Co gamma irradiation effect on nonlinear optical L-alanine cadmium chloride single crystals

    International Nuclear Information System (INIS)

    Single crystal of nonlinear optical (NLO) material L-alanine cadmium chloride (LACC) was grown by slow evaporation method at room temperature. The grown crystals were irradiated with 95 MeV oxygen ions and 60Co gamma radiation at doses of 1 Mrad and 6 Mrad. The structural, chemical, dielectric properties, AC and DC conductivity, refractive index of the crystals were studied before and after irradiation. There is a slight change in the lattice parameters due to compressive strain field generated in the irradiated crystals. The observed increase in dielectric constant was found to be more for 60Co gamma irradiated crystals than 95 MeV oxygen ion irradiated crystal. A considerable change in the values of refractive indices was observed for both gamma and ion irradiated crystals. The AC and DC conductivity was found to increase after irradiation. (author)

  10. Comparison of CALIPSO-Like, LaRC, and MODIS Retrievals of Ice Cloud Properties over SIRTA in France and Florida during CRYSTAL-FACE

    Science.gov (United States)

    Chiriaco, M.; Chepfer, H.; Haeffelin, M.; Minnis, P.; Noel, V.; Platnick, S.; McGill, M.; Baumgardner, D.; Dubuisson, P.; Pelon, J.; Spangenberg, D.; Sun-Mack, S.; Wind, G.

    2007-01-01

    This study compares cirrus particle effective radius retrieved by a CALIPSO-like method with two similar methods using MODIS, MODI Airborne Simulator (MAS), and GOES imagery. The CALIPSO-like method uses lidar measurements coupled with the split-window technique that uses the infrared spectral information contained at the 8.65-micrometer, 11.15-micrometer and 12.05-micrometer bands to infer the microphysical properties of cirrus clouds. The two other methods, sing passive remote sensing at visible and infrared wavelengths, are the operational MODIS cloud products (referred to by its archival product identifier MOD06 for MODIS Terra) and MODIS retrievals performed by the CERES team at LaRC (Langley Research Center) in support of CERES algorithms; the two algorithms will be referred to as MOD06- and LaRC-method, respectively. The three techniques are compared at two different latitudes: (i) the mid-latitude ice clouds study uses 18 days of observations at the Palaiseau ground-based site in France (SIRTA: Site Instrumental de Recherche par Teledetection Atmospherique) including a ground-based 532 nm lidar and the Moderate Resolution Imaging Spectrometer (MODIS) overpasses on the Terra Platform, (ii) the tropical ice clouds study uses 14 different flight legs of observations collected in Florida, during the intensive field experiment CRYSTAL-FACE (Cirrus Regional Study of Tropical Anvils and cirrus Layers-Florida Area Cirrus Experiment), including the airborne Cloud Physics Lidar (CPL) and the MAS. The comparison of the three methods gives consistent results for the particle effective radius and the optical thickness, but discrepancies in cloud detection and altitudes. The study confirms the value of an active remote-sensing method (CALIPSO-like) for the study of sub-visible ice clouds, in both mid-latitudes and tropics. Nevertheless, this method is not reliable in optically very thick tropical ice clouds.

  11. Timing characteristics of Ce doped Gd3Ga3Al2O12 single crystals in comparison with CsI(Tl) scintillators

    International Nuclear Information System (INIS)

    Single crystals of Gd3Ga3Al2O12:Ce with B codopants were successfully grown using the Czochralski technique. The timing characteristics of the crystal was measured by coupling the crystal to photomultiplier tubes (PMT) or silicon photodiodes [Si(PIN)]. The two prompt γ-rays emitted in a cascade from 60Co or 22Na source were detected in coincidence using Gd3Ga3Al2O12:Ce,B crystal detectors and a BaF2 detector. The time resolution of these crystals are observed to be better than that measured for CsI:Tl crystal coupled to PMT or Si(PIN) in an identical measurement setup. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. The medium energy transfer spectrometer; a crystal monochromator design

    International Nuclear Information System (INIS)

    The report is in sections, entitled: introduction; scientific specification; monochromators (single crystal geometry; double crystal geometry; choice of crystals (copper)); an initial mechanical design; the resolution of the MET crystal monochromator (collimation; resolution calculations; comparison with other spectrometers); specifications of the MET (crystal) spectrometer; suppression of high orders; intensity calculations (intensity comparisons between crystal and chopper versions of (MET); neutron momentum transfer resolution. (U.K.)

  13. Crystal Meth

    Science.gov (United States)

    ... for: Navigation Home / Stories of Hope / Crystal meth Crystal meth Story Of Hope By giovanni January 3rd, ... about my drug addiction having to deal with Crystal meth. I am now in recovery and fighting ...

  14. Structural study of vapour phase deposited 3,4,9,10-perylene tetracarboxylicacid diimide: Comparison between single crystal and ultra thin films grown on Pt(100)

    International Nuclear Information System (INIS)

    Structural properties of a single crystal and of a thin film of 3,4,9,10-perylene-tetracarboxylic-acid-diimide are compared. The two samples are both obtained from the vapour phase, the latter being deposited at room temperature, in an ultrahigh vacuum environment, on a clean Pt(100) substrate. In the single crystal we have pointed out interactions between adjacent molecules by overlapping of the π systems in the stacks and by hydrogen bonds between neighbouring stacks. The various surface unit cells of the nanocrystals from the film, identified by means of scanning tunnelling microscopy, are not comparable to those expected from the X-ray diffraction study of the single crystal and to those already published for other substrates. This fact clearly highlights the role played by the type of substrate chosen and/or the substrate-molecule interaction that affects the stacking and crystallinity of the growing crystal on top

  15. Comparison of a mosaic-crystal spectrometer to a high-performance solid-state detector for x-ray microfluorescence analysis

    International Nuclear Information System (INIS)

    The minimum-detectable-limit of a compact double-focusing graphite mosaic-crystal spectrometer is compared to the minimum-detectable-limit from a high-performance Ge solid-state detector. The solid angle and efficiency of the solid-state detector is much greater than for the crystal spectrometer. However, the better signal-to-noise of the spectrometer and its insensitivity to matrix fluorescence and scattering can give it a better minimum-detectable-limit for trace element analysis. The relative advantages of the two detectors are illustrated for some simple test samples. The performance of the crystal spectrometer compared to the solid-state detector increases as the flux in the x-ray probe increases. This makes crystal spectrometers especially interesting for use with new high intensity 3rd generation synchrotron microprobes. An estimate is made of the source and sample conditions favored for each detector

  16. Mode-locking characteristics comparison at 1.34 μm between Nd:Gd x Y1-x VO4 series crystals

    Science.gov (United States)

    Qiao, Wenchao; Chu, Hongwei; Zhao, Shengzhi; Li, Guiqiu; Yang, Kejian; Li, Tao; Zhao, Jia; Zhang, Baitao; He, Jingliang

    2016-04-01

    Passively continuous-wave mode-locking (CWML) characteristics from a class of mixed Nd:Gd x Y1-x VO4 laser crystals at 1.34 μm have been investigated with a semiconductor saturable absorber mirror (SESAM) for the first time. In contrast to the single Nd:YVO4 and Nd:GdVO4 crystals, the mixed vanadate crystals can produce broader emission spectra, shorter pulse width, and higher peak power. Under the same conditions, the mode-locking performances from series mixed vanadate crystals as well as the emitting spectral properties were experimentally investigated. At an incident diode pump power of 7.1 W, a minimum pulse width was as short as 6.3 ps from the mixed vanadate crystal with x  =  0.63, while the highest peak power was 4.5 kW from the mixed crystal with x  =  0.83.

  17. Aluminum induced proteome changes in tomato cotyledons

    Science.gov (United States)

    Cotyledons of tomato seedlings that germinated in a 20 µM AlK(SO4)2 solution remained chlorotic while those germinated in an aluminum free medium were normal (green) in color. Previously, we have reported the effect of aluminum toxicity on root proteome in tomato seedlings (Zhou et al. J Exp Bot, 20...

  18. Comparison of the inhibitory capacity of two groups of pure natural extract on the crystallization of two types of material compound urinary stones in vitro study

    Science.gov (United States)

    Beghalia, Mohamed; Ghalem, Said; Allali, Hocine

    2015-10-01

    Urolithiasis is defined as the result of an abnormal precipitation within the urinary tract. This precipitation is most often from the normal constituents of the urine. This is a fairly common condition in the population. She is happy and recurrent etiology is often unknown if hypothetical. In Algeria, as in many countries, a large number of patients use herbal medicines in the treatment of their diseases including urolithiasis. Thus the aim of this study is the most widely used to evaluate the effectiveness of aqueous extracts of medicinal plants, in the treatment of calcium urolithiasis oxalo-and magnesium-amoniaco in vitro. The study also examines the effect of these extracts on the states of crystallization (nucleation, crystal growth, crystal aggregation), followed by photography on polarized light microscope.In this regard, we are devoted to studying the crystallization steps from oxalo-calcium and phospho-calcic prepared as artificial urine and supersaturated aqueous solutions, maintained at 37 °C to remain close to biological conditions. Extracts of the first group of herbs: Ammodaucus leucotrichus, Ajuga iva, Globularia alypum, Atriplex halimus are studied on the crystallization calcium oxalate, we cite the Ammodaucus leucotrichus which acts on the stages of nucleation, growth and the aggregation with a total inhibition. The second group of extracts plants tested on calcium phosphate crystallization : Acacia raddiana, Citrullus colocynthis, Rhus tripartita, Pistacia lentiscu, Warionia saharae, are able to significantly reduce phosphate crystallization in vitro. It is easily proved by FTIR and optical microscope. In conclusion the results of our work allows us to confirm the use of these plants as an aqueous decoction, in the field of urolithiasis. These activities may help to strengthen the body in depressed situations.

  19. Comparison and characterization of efficient frequency doubling at 397.5 nm with PPKTP, LBO and BiBO crystals

    Science.gov (United States)

    Wen, Xin; Han, Yashuai; Wang, Junmin

    2016-04-01

    A continuous-wave Ti:sapphire laser at 795 nm is frequency doubled in a bow-tie type enhancement four-mirror ring cavity with LiB3O5 (LBO), BiB3O6 (BiBO), and periodically polled KTiOPO4 (PPKTP) crystals, respectively. The properties of 397.5 nm ultra-violet (UV) output power, beam quality, stability for these different nonlinear crystals are investigated and compared. For PPKTP crystal, the highest doubling efficiency of 58.1% is achieved from 191 mW of 795 nm mode-matched fundamental power to 111 mW of 397.5 nm UV output. For LBO crystal, with 1.34 W of mode-matched 795 nm power, 770 mW of 397.5 nm UV output is achieved, implying a doubling efficiency of 57.4%. For BiBO crystal, with 323 mW of mode-matched 795 nm power, 116 mW of 397.5 nm UV output is achieved, leading to a doubling efficiency of 35.9%. The generated UV radiation has potential applications in the fields of quantum physics.

  20. Comparison of staining of mitotic figures by haematoxylin and eosin-and crystal violet stains, in oral epithelial dysplasia and squamous cell carcinoma

    Directory of Open Access Journals (Sweden)

    Ankle Madhuri

    2007-01-01

    Full Text Available Mitosis of cells gives rise to tissue integrity. Defects during mitosis bring about abnormalities. Excessive proliferation of cells due to increased mitosis is one such outcome, which is the hallmark in precancer and cancer. The localization of proliferating cells or their precursors may not be obvious and easy. Establishing an easy way to distinguish these mitotic cells will help in grading and understanding their biological potential. Although immunohistochemistry is an advanced method in use, the cost and time factor makes it less feasible for many laboratories. Selective histochemical stains like toluidine blue, giemsa and crystal violet have been used in tissues including the developing brain, neural tissue and skin. Aim of the study: 1To compare the staining of mitotic cells in haematoxylin and eosin with that in crystal violet. 2To compare the number of mitotic figures present in normal oral mucosa, epithelial dysplasia and oral squamous cell carcinoma in crystal violet-stained sections with that in H and E-stained sections. Materials and Methods: Ten tissues of normal oral mucosa and 15 tissues each of oral epithelial dysplasia seen in tobacco-associated leukoplakia and squamous cell carcinoma were studied to evaluate the selectivity of 1% crystal violet for mitotic figures. The staining was compared with standard H and E staining. Statistical analysis was done using Man-Whitney U test. Results: A statistically significant increase in the mean mitotic count was observed in crystal violet-stained sections of epithelial dysplasia as compared to the H and E-stained sections ( p = 0.0327. A similar increase in the mitotic counts was noted in crystal violet-stained sections of oral squamous cell carcinoma as compared to the H and E-stained sections.( p = 0.0443. No significant difference was found in the mitotic counts determined in dysplasia or carcinoma by either the crystal violet ( p = 0.4429 or the H and E-staining techniques ( p = 0

  1. Crystals in crystals

    DEFF Research Database (Denmark)

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

    2005-01-01

    the outer surface 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........ As representative examples, a metal (Pt), an alloy (PtSn), and a metal carbide (beta-Mo2C) were supported on conventional and mesoporous zeolite carriers, respectively, and the degree of particle dispersion was compared by TEM imaging. On conventional zeolites, the supported material aggregated on...

  2. 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.

  3. In-situ metrology for the optimization of bent crystals used in hard-X-ray monochromators: Comparison between measurement and simulation

    Science.gov (United States)

    Thomasset, Muriel; Moreno, Thierry; Capitanio, Blandine; Idir, Mourad; Bucourt, Samuel

    2010-05-01

    Crystal sagittal focusing is known as one of the most efficient way of focusing synchrotron X-ray radiation from bending magnet sources, thus delivering increases photon flux at the sample position. To optimize the performance of a sagittaly bent crystal inside a monochromator, it is necessary to have knowledge of its radius of curvature. However, this measurement is not very easy to obtain. Even though the use of the X-ray beam is the ultimate source for optimizing the system, it is still necessary to have a prior knowledge of the radius of curvature as a function of the motor bender positions to avoid any catastrophic failure. In this paper, we describe a simple, efficient and accurate method of measuring the radius of curvature of sagitally bent monochromator crystals at several bending magnet beamlines at synchrotron SOLEIL. To optimize the crystal bending inside these monochromators, we used a Shack-Hartmann sensor (HP 26) developed by the Imagine Optic Company (Orsay/France). This high accuracy two-dimensional metrology tool was originally designed to be installed on a Long Trace Profiler translation stage to measure the mirrors profiles. During a period where the SOLEIL synchrotron was in shutdown, this instrument was directly mounted inside the monochromator so that the radius of curvature could be measured in-situ. This method allows us to optimize the curvature and eliminate twist before bending strongly the crystal below radii of curvature of less than 2 m. The second step in the optimization process was to use the X-ray beam for the final adjustments of the bending system, where X-ray images are then used to analyse the residual defaults of the system. Using SpotX, a ray-tracing simulation tool, these errors can be fully analysed and a fully optimized system can then be obtained. Overall, five beamlines at synchrotron SOLEIL have used in this method to optimize their monochromators.

  4. A comparison of the X-ray performance of TlBr crystals grown by the Bridgeman-Stockbarger and travelling molten zone methods

    Energy Technology Data Exchange (ETDEWEB)

    Gostilo, V. E-mail: bsi@bsi.lv; Owens, A.; Bavdaz, M.; Lisjutin, I.; Peacock, A.; Sipila, H.; Zatoloka, S

    2003-08-21

    We have investigated at optimal temperature the X-ray detection characteristics of two TlBr crystals by the Traveling Molten Zone (TMZ) technique. The resistivities were typically 1.5x10{sup 10} {omega} cm at room temperature, increasing to (1.1-1.7)x10{sup 12} {omega} cm at -15 deg. C. In the temperature range -0 deg. C to -50 deg. C, both crystals exhibited mobility-lifetime products of {approx}8x10{sup -5} cm{sup 2}V{sup -1} and {approx}1.5x10{sup -5} cm{sup 2}V{sup -1}, for electrons and holes respectively. From these crystals, two detectors were packaged and X-ray metrology carried out. For the best detector, the measured energy resolutions at an operating temperature of -15 deg. C and 500 V bias were 1.0 keV at 5.9 keV; 1.1 at 13.9 keV; 2.5 at 59.54 keV; 3.3 keV at 88 keV; 4 keV at 122 keV and 27.7 keV at 662 keV.A comparative analysis of the characteristics of detectors grown by TMZ to those grown by the Bridgeman-Stockbarger method is given.

  5. A comparison of the X-ray performance of TlBr crystals grown by the Bridgeman-Stockbarger and travelling molten zone methods

    International Nuclear Information System (INIS)

    We have investigated at optimal temperature the X-ray detection characteristics of two TlBr crystals by the Traveling Molten Zone (TMZ) technique. The resistivities were typically 1.5x1010 Ω cm at room temperature, increasing to (1.1-1.7)x1012 Ω cm at -15 deg. C. In the temperature range -0 deg. C to -50 deg. C, both crystals exhibited mobility-lifetime products of ∼8x10-5 cm2V-1 and ∼1.5x10-5 cm2V-1, for electrons and holes respectively. From these crystals, two detectors were packaged and X-ray metrology carried out. For the best detector, the measured energy resolutions at an operating temperature of -15 deg. C and 500 V bias were 1.0 keV at 5.9 keV; 1.1 at 13.9 keV; 2.5 at 59.54 keV; 3.3 keV at 88 keV; 4 keV at 122 keV and 27.7 keV at 662 keV.A comparative analysis of the characteristics of detectors grown by TMZ to those grown by the Bridgeman-Stockbarger method is given

  6. Comparison between beryllium and diamond-backing plates in diamond-anvil cells: Application to single-crystal X-ray diffraction high-pressure data

    DEFF Research Database (Denmark)

    Periotto, Benedetta; Nestola, Fabrizio; Balic Zunic, Tonci;

    2011-01-01

    A direct comparison between two complete intensity datasets, collected on the same sample loaded in two identical diamond-anvil pressure cells equipped, respectively, with beryllium and diamond backing plates was performed. The results clearly demonstrate that the use of diamond-backing plates...

  7. Protein Crystal Isocitrate Lyase

    Science.gov (United States)

    1998-01-01

    The comparison of protein crystal, Isocitrate Lyase earth-grown (left) and space-grown (right). This is a target enzyme for fungicides. A better understanding of this enzyme should lead to the discovery of more potent fungicides to treat serious crop diseases such as rice blast; it regulates the flow of metabolic intermediates required for cell growth. Principal Investigator is Larry DeLucas.

  8. TL response of single crystal TLD-100 to 70 eV: 5 keV electrons and comparison with TSEE glow curves

    Energy Technology Data Exchange (ETDEWEB)

    Lasky, J.B.; Moran, P.R.

    1976-01-01

    A ''TL effective'' energy-range relationship was found which agrees with the universal curve above 2 keV but becomes nearly constant at about 300/sup 0/A for energies between 1 keV and 100 eV. The glow curve shape obtained from single crystal TLD-100, after irradiation with 70 eV to 30 keV electrons, is essentially the same as that obtained after irradiation with cesium ..gamma..-rays, (i.e. TL emitted from bulk of sample) as long as (1) the dose is well below saturation and (2) irradiations are performed on freshly cleaved crystals or vacuum annealed crystals. This result shows that there is no intrinsic difference between TL traps near the surface and in the bulk. Irradiation with electron energies less than 1 keV results in the TL signal being emitted from the same region from which TSEE electrons are emitted. The usual TSEE glow curve, found by other investigators, is different from the TL glow curve obtained from vacuum annealed crystals. However, if the TL sample is given the same ''standard annealing'' as is customary in TSEE experiments, the TL glow curve obtained after irradiation with low energy electrons is altered and there is then good agreement between this TL glow curve and the TSEE curve found by others. This altered glow curve is a result of hydroxyl ions which diffuse into the sample during annealing. The TL efficiency was comparable to cesium ..gamma..-rays for 30-5 keV electrons, decreased rapidly between 5 and 1 keV and remained constant at about 20% of the efficiency of cesium ..gamma..-rays below 1 keV. Half of this decrease in efficiency can be attributed to the higher LET of low energy electrons. The cause for the remaining decrease is not known but it may have its origin in the same mechanism proposed to account for the large range of low energy electrons.

  9. Comparison of neutron capture spectra taken by a constellation Xe-110 detector and a 1'x1' NaI(Tl) crystal

    International Nuclear Information System (INIS)

    Constellation Technology Corporation has developed a spectroscopic nuclear detector called the Xe-110 that is well suited for downhole use in oil and gas well logging. The advantages possessed by this detector over traditional technologies such as NaI(Tl) scintillators are summarized. We discuss an analysis of gamma-ray spectra taken by the Xe-110, which suggests that the superior energy resolution and low background level of this detector enables identification of important features in neutron activation spectra of hydrocarbons that might not be identifiable using an NaI(Tl) crystal. (author)

  10. Protein Crystallization

    Science.gov (United States)

    Chernov, Alexander A.

    2005-01-01

    Nucleation, growth and perfection of protein crystals will be overviewed along with crystal mechanical properties. The knowledge is based on experiments using optical and force crystals behave similar to inorganic crystals, though with a difference in orders of magnitude in growing parameters. For example, the low incorporation rate of large biomolecules requires up to 100 times larger supersaturation to grow protein, rather than inorganic crystals. Nucleation is often poorly reproducible, partly because of turbulence accompanying the mixing of precipitant with protein solution. Light scattering reveals fluctuations of molecular cluster size, its growth, surface energies and increased clustering as protein ages. Growth most often occurs layer-by-layer resulting in faceted crystals. New molecular layer on crystal face is terminated by a step where molecular incorporation occurs. Quantitative data on the incorporation rate will be discussed. Rounded crystals with molecularly disordered interfaces will be explained. Defects in crystals compromise the x-ray diffraction resolution crucially needed to find the 3D atomic structure of biomolecules. The defects are immobile so that birth defects stay forever. All lattice defects known for inorganics are revealed in protein crystals. Contribution of molecular conformations to lattice disorder is important, but not studied. This contribution may be enhanced by stress field from other defects. Homologous impurities (e.g., dimers, acetylated molecules) are trapped more willingly by a growing crystal than foreign protein impurities. The trapped impurities induce internal stress eliminated in crystals exceeding a critical size (part of mni for ferritin, lysozyme). Lesser impurities are trapped from stagnant, as compared to the flowing, solution. Freezing may induce much more defects unless quickly amorphysizing intracrystalline water.

  11. Computational crystallization.

    Science.gov (United States)

    Altan, Irem; Charbonneau, Patrick; Snell, Edward H

    2016-07-15

    Crystallization is a key step in macromolecular structure determination by crystallography. While a robust theoretical treatment of the process is available, due to the complexity of the system, the experimental process is still largely one of trial and error. In this article, efforts in the field are discussed together with a theoretical underpinning using a solubility phase diagram. Prior knowledge has been used to develop tools that computationally predict the crystallization outcome and define mutational approaches that enhance the likelihood of crystallization. For the most part these tools are based on binary outcomes (crystal or no crystal), and the full information contained in an assembly of crystallization screening experiments is lost. The potential of this additional information is illustrated by examples where new biological knowledge can be obtained and where a target can be sub-categorized to predict which class of reagents provides the crystallization driving force. Computational analysis of crystallization requires complete and correctly formatted data. While massive crystallization screening efforts are under way, the data available from many of these studies are sparse. The potential for this data and the steps needed to realize this potential are discussed. PMID:26792536

  12. Comparison of the properties of tonpilz transducers fabricated with 001 fiber-textured lead magnesium niobate-lead titanate ceramic and single crystals.

    Science.gov (United States)

    Brosnan, Kristen H; Messing, Gary L; Markley, Douglas C; Meyer, Richard J

    2009-11-01

    Tonpilz transducers are fabricated from 001 fiber-textured 0.72Pb(Mg(1/3)Nb(2/3))O(3)-0.28PbTiO(3) (PMN-28PT) ceramics, obtained by the templated grain growth process, and PMN-28PT ceramic and Bridgman grown single crystals of the same composition. In-water characterization of single element transducers shows higher source levels, higher in-water coupling, and more usable bandwidth for the 81 vol % textured PMN-28PT device than for the ceramic PMN-28PT element. The 81 vol % textured PMN-28PT tonpilz element measured under large signals shows linearity in sound pressure levels up to 0.23 MV/m drive field but undergoes a phase transition due to a lowered transition temperature from the SrTiO(3) template particles. Although the textured ceramic performs well in this application, it could be further improved with compositional tailoring to raise the transition temperature and better processing to improve the texture quality. With these improvements textured piezoelectric ceramics will be viable options for medical ultrasound, actuators, and sonar applications because of their ease of processing, compositional homogeneity, and potentially lower cost than single crystal. PMID:19894807

  13. Protein Crystal Recombinant Human Insulin

    Science.gov (United States)

    1994-01-01

    The comparison of protein crystal, Recombiant Human Insulin; space-grown (left) and earth-grown (right). On STS-60, Spacehab II indicated that space-grown crystals are larger and of greater optical clarity than their earth-grown counterparts. Recombiant Human Insulin facilitates the incorporation of glucose into cells. In diabetics, there is either a decrease in or complete lack of insulin, thereby leading to several harmful complications. Principal Investigator is Larry DeLucas.

  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. Toward the solution structure of human insulin: Sequential 2D 1H NMR assignment of a des-pentapeptide analogue and comparison with crystal structure

    International Nuclear Information System (INIS)

    2D 1H NMR studies are presented of des-pentapeptide-insulin, an analogue of human insulin lacking the C-terminal five residues of the B chain. Removal of these residues, which are not required for function, is shown to reduce conformational broadening previously described in the spectrum of intact insulin. This difference presumably reflects more rapid internal motions in the fragment, which lead to more complete averaging of chemical shifts on the NMR time scale. Sequential 1H NMR assignment and preliminary structural analysis demonstrate retention in solution of the three α-helices observed in the crystal state and the relative orientation of the receptor-binding surfaces. These studies provide a foundation for determining the solution structure of insulin

  16. Toward the solution structure of human insulin: Sequential 2D sup 1 H NMR assignment of a des-pentapeptide analogue and comparison with crystal structure

    Energy Technology Data Exchange (ETDEWEB)

    Hua, Q.; Weiss, M.A. (Harvard Medical School, Boston, MA (USA) Massachusetts Institute of Technology, Cambridge (USA))

    1990-11-01

    2D {sup 1}H NMR studies are presented of des-pentapeptide-insulin, an analogue of human insulin lacking the C-terminal five residues of the B chain. Removal of these residues, which are not required for function, is shown to reduce conformational broadening previously described in the spectrum of intact insulin. This difference presumably reflects more rapid internal motions in the fragment, which lead to more complete averaging of chemical shifts on the NMR time scale. Sequential {sup 1}H NMR assignment and preliminary structural analysis demonstrate retention in solution of the three {alpha}-helices observed in the crystal state and the relative orientation of the receptor-binding surfaces. These studies provide a foundation for determining the solution structure of insulin.

  17. Liquid crystal tunable photonic crystal dye laser

    OpenAIRE

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

    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.

  18. Molecular Crystals

    Science.gov (United States)

    Wright, John D.

    1995-02-01

    This book describes the chemical and physical structure of molecular crystals, their optical and electronic properties, and the reactions between neighboring molecules in crystals. In the second edition, the author has taken into account research that has undergone extremely rapid development since the first edition was published in 1987. For instance, he gives extensive coverage to the applications of molecular materials in high-technology devices (e.g. optical communications, laser printers, photocopiers, liquid crystal displays, solar cells, and more). There is also an entirely new chapter on the recently discovered Buckminsterfullerene carbon molecule (C60) and organic non-linear optic materials.

  19. 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....

  20. Comparison of observer performance on soft-copy reading of digital chest radiographs: High resolution liquid-crystal display monitors versus cathode-ray tube monitors

    International Nuclear Information System (INIS)

    The purpose of this study is to compare observer performance for detection of abnormalities on chest radiographs with 5-megapixel resolution liquid-crystal displays (LCD) and 5-megapixel resolution cathode-ray tube (CRT) monitors under bright and subdued ambient light conditions. Six radiologists reviewed a total of 254 digital chest radiographs under four different conditions with a combination of two types of monitors (a 5-megapixel resolution LCD and a 5-megapixel resolution CRT monitor) and with two types of ambient light (460 and 50 lux). The abnormalities analyzed were nodules, pneumothorax and interstitial lung disease. For each reader, the detection performance using 5-megapixel LCD and 5-megapixel CRT monitors under bright and subdued ambient light conditions were compared using multi-case and multi-modality ROC analysis. For each type of ambient light, the average detection performance with the two types of monitors was also compared. For each reader, the observer performance of 5-megapixel LCD and 5-megapixel CRT monitors, under both bright and subdued ambient light conditions, showed no significant statistical differences for detecting nodules, pneumothorax and interstitial lung disease. In addition, there was no significant statistical difference in the average performance when the two monitor displays, under both bright and subdued ambient light conditions, were compared

  1. The Crystal Structure of Ba 3CuRu 2O 9 and Comparison to Ba 3MRu 2O 9 ( M=In, Co, Ni, and Fe)

    Science.gov (United States)

    Rijssenbeek, J. T.; Huang, Q.; Erwin, R. W.; Zandbergen, H. W.; Cava, R. J.

    1999-08-01

    The crystal structure of Ba3CuRu2O9, determined by powder neutron diffraction, is reported for temperatures of 18-295 K. Structural refinements by powder neutron diffraction for the previously reported compounds Ba3MRu2O9 for M=Fe, Co, Ni, and In are also reported. All structures consist of pairs of face-shared RuO6 octahedra interconnected by corner-sharing MO6 octahedra. For Ba3CuRu2O9, Jahn-Teller distortion of the CuO6 octahedra leads to an orthorhombic symmetry structure of space group Cmcm with a=5.6723(1), b=10.1722(3), and c=14.1575(3) Å at 295 K. For Ba3FeRu2O9, site occupancy disorder is found. Magnetic ordering is observed below 100, 105, and 110 K for M=Cu, Ni, and Co, respectively. The magnetic structures at low temperatures for M=Co and Ni are described and compared to previous reports.

  2. Holographic Interferometry based on photorefractive crystal to measure 3D thermo-elastic distortion of composite structures and comparison with finite element models

    Science.gov (United States)

    Thizy, C.; Eliot, F.; Ballhause, D.; Olympio, K. R.; Kluge, R.; Shannon, A.; Laduree, G.; Logut, D.; Georges, M. P.

    2013-04-01

    Thermo-elastic distortions of composite structures have been measured by a holographic camera using a BSO photorefractive crystal as the recording medium. The first test campaign (Phase 1) was performed on CFRP struts with titanium end-fittings glued to the tips of the strut. The samples were placed in a vacuum chamber. The holographic camera was located outside the chamber and configured with two illuminations to measure the relative out-of-plane and in-plane (in one direction) displacements. The second test campaign (Phase 2) was performed on a structure composed of a large Silicon Carbide base plate supported by 3 GFRP struts with glued Titanium end-fittings. Thermo-elastic distortions have been measured with the same holographic camera used in phase 1, but four illuminations, instead of two, have been used to provide the three components of displacement. This technique was specially developed and validated during the phase 2 in CSL laboratory. The system has been designed to measure an object size of typically 250x250 mm2; the measurement range is such that the sum of the largest relative displacements in the three measurement directions is maximum 20 μm. The validation of the four-illuminations technique led to measurement uncertainties of 120 nm for the relative in-plane and out-of-plane displacements, 230 nm for the absolute in-plane displacement and 400 nm for the absolute out-of-plane displacement. For both campaigns, the test results have been compared to the predictions obtained by finite element analyses and the correlation of these results was good.

  3. Influence of microgravity on protein crystal structures

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Structural determination and comparison of microgravity and ground grown protein crystals have been carried out in order to investigate the effect of microgravity on the structure of protein crystals. Following the structural studies on the hen egg-white lysozyme cystals grown in space and on the ground, the same kind of comparative studies was performed with acidic phospholipase A2 crystals grown in different gravities. Based on the results obtained so far, a conclusion could be made that microgravity might not be strong enough to change the conformation of polypeptide chain of proteins, but it may improve the bound waters' structure, and this might be an important factor for microgravity to improve the protein crystal quality. In addition, the difference in the improvement between the two kinds of protein crystals may imply that the degree of improvement of a protein crystal in microgravity may be related to the solvent content in the protein crystal.

  4. Liquid Crystals

    Science.gov (United States)

    1990-01-01

    Thermochromic liquid crystals, or TLCs, are a type of liquid crystals that react to changes in temperature by changing color. The Hallcrest/NASA collaboration involved development of a new way to visualize boundary layer transition in flight and in wind tunnel testing of aircraft wing and body surfaces. TLCs offered a new and potentially better method of visualizing the boundary layer transition in flight. Hallcrest provided a liquid crystal formulation technique that afforded great control over the sensitivity of the liquid crystals to varying conditions. Method is of great use to industry, government and universities for aerodynamic and hydrodynamic testing. Company's principal line is temperature indicating devices for industrial use, such as non-destructive testing and flaw detection in electric/electronic systems, medical application, such as diagnostic systems, for retail sale, such as room, refrigerator, baby bath and aquarium thermometers, and for advertising and promotion specials. Additionally, Hallcrest manufactures TLC mixtures for cosmetic applications, and liquid crystal battery tester for Duracell batteries.

  5. Size effects in crystal plasticity

    DEFF Research Database (Denmark)

    Borg, Ulrik

    2007-01-01

    growth and interaction between neighboring voids, and on a comparison between the developed strain gradient crystal plasticity theory and a discrete dislocation plasticity theory. Furthermore, voids and rigid inclusions in isotropic materials have been studied using a strain gradient plasticity theory......Numerical analyses of plasticity size effects have been carried out for different problems using a developed strain gradient crystal plasticiy theory. The theory employs higher order stresses as work conjugates to slip gradients and uses higher order boundary conditions. Problems on localization...... of plastic flow in a single crystal, grain boundary effects in a bicrystal, and grain size effects in a polycrystal are studied. Single crystals containing micro-scale voids have also been analyzed at different loading conditions with focus on the stress and deformation fields around the voids, on void...

  6. Photonic crystals

    CERN Document Server

    Busch, Kurt; Wehrspohn, Ralf B; Föll, Helmut

    2006-01-01

    The majority of the contributions in this topically edited book stems from the priority program SPP 1113 ""Photonische Kristalle"" run by the Deutsche Forschungsgemeinschaft (DFG), resulting in a survey of the current state of photonic crystal research in Germany. The first part of the book describes methods for the theoretical analysis of their optical properties as well as the results. The main part is dedicated to the fabrication, characterization and modeling of two- and three-dimensional photonic crystals, while the final section presents a wide spectrum of applications: gas sensors, micr

  7. Photonic crystals principles and applications

    CERN Document Server

    Gong, Qihuang

    2013-01-01

    IntroductionPrimary Properties of Photonic CrystalsFabrication of Photonic CrystalsPhotonic Crystal All-Optical SwitchingTunable Photonic Crystal FilterPhotonic Crystal LaserPhotonic Crystal Logic DevicesPhotonic Crystal Sensors

  8. Timing characteristics of Ce doped Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12} single crystals in comparison with CsI(Tl) scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Tyagi, M.; Singh, A.K.; Singh, S.G.; Sen, S.; Gadkari, S.C. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai, 400085 (India); Desai, V.V.; Nayak, B.K. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai, 400085 (India)

    2015-10-15

    Single crystals of Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12}:Ce with B codopants were successfully grown using the Czochralski technique. The timing characteristics of the crystal was measured by coupling the crystal to photomultiplier tubes (PMT) or silicon photodiodes [Si(PIN)]. The two prompt γ-rays emitted in a cascade from {sup 60}Co or {sup 22}Na source were detected in coincidence using Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12}:Ce,B crystal detectors and a BaF{sub 2} detector. The time resolution of these crystals are observed to be better than that measured for CsI:Tl crystal coupled to PMT or Si(PIN) in an identical measurement setup. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Hydrothermal crystal growth of the potassium niobate and potassium tantalate family of crystals

    International Nuclear Information System (INIS)

    Single crystals of KNbO3 (KN), KTaO3 (KT), and KTa1-xNbxO3 (x=0.44, KTN) have been prepared by hydrothermal synthesis in highly concentrated KOH mineralizer solutions. The traditional problems of inhomogeneity, non-stoichiometry, crystal striations and crystal cracking resulting from phase transitions associated with this family compounds are minimized by the hydrothermal crystal growth technique. Crystals of good optical quality with only minor amounts of metal ion reduction can be grown this way. Reactions were also designed to provide homogeneous distribution of tantalum and niobium metal centers throughout the KTN crystal lattice to maximize its electro-optic properties. Synthesis was performed at relatively low (500-660 oC) temperatures in comparison to the flux and Czochralski techniques. This work represents the largest crystals of this family of compounds grown by hydrothermal methods to date. -- Graphical Abstract:

  10. 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...... using planar triangles and cylindrical arcs, and the ribbon structure is shown to arise from a maximization of the end-to-end length of the ribbon, i.e. from an optimal use of ribbon length. The phenomenon is discussed in the perspectives of incompatible intrinsic geometries and of the emergence of long...

  11. Process Modeling for Batch Cooling Crystallization

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The general mathematical model for batch cooling crystallization was established based on the popula tion balance equation considering the change of slurry volume, and simulated with crystallization thermodynamics, kinetics and mass balance employing bed voidage. In the system of vitamin C-water-ethanol, reliability of this model was verified by comparison between simulation results and experimental data. The effects of operation parameters on product quality can be systematically investigated by modeling simulation.

  12. Process Modeling for Batch Cooling Crystallization

    Institute of Scientific and Technical Information of China (English)

    陈慧萍; 王静康

    2001-01-01

    The general mathematical model for batch cooling crystallization was established based on the population balance equation considering the change of slurry volume, and simulated with crystallization thermodynamics,kinetics and mass balance employing bed voidage. In the system of vitamin C-water-ethanol, reliability of this model was verified by comparison between simulation results and experimental data. The effects of operation parameters on product quality can be systematically investigated by modeling simulation.

  13. F 3 - molecular ions in fluoride crystals

    Science.gov (United States)

    Radzhabov, E. A.

    2016-02-01

    The UV absorption spectra of F 3 - molecular ions in LaF3, SrF2, CaF2, and BaF2 crystals doped with rare-earth elements are studied. Comparison of radiation-colored and additively colored crystals reveals the absorption bands of F 3 - hole centers in the region near 6 eV. Nonempirical calculations of optical transitions agree well with experimental results.

  14. Biological Macromolecule Crystallization Database

    Science.gov (United States)

    SRD 21 Biological Macromolecule Crystallization Database (Web, free access)   The Biological Macromolecule Crystallization Database and NASA Archive for Protein Crystal Growth Data (BMCD) contains the conditions reported for the crystallization of proteins and nucleic acids used in X-ray structure determinations and archives the results of microgravity macromolecule crystallization studies.

  15. Single crystal U-Pb zircon age and Sr-Nd isotopic composition of impactites from the Bosumtwi impact structure, Ghana: Comparison with country rocks and Ivory Coast tektites.

    Science.gov (United States)

    Ferrière, Ludovic; Koeberl, Christian; Thöni, Martin; Liang, Chen

    2010-08-01

    The 1.07 Myr old Bosumtwi impact structure (Ghana), excavated in 2.1-2.2 Gyr old supracrustal rocks of the Birimian Supergroup, was drilled in 2004. Here, we present single crystal U-Pb zircon ages from a suevite and two meta-graywacke samples recovered from the central uplift (drill core LB-08A), which yield an upper Concordia intercept age of ca. 2145 ± 82 Ma, in very good agreement with previous geochronological data for the West African Craton rocks in Ghana. Whole rock Rb-Sr and Sm-Nd isotope data of six suevites (five from inside the crater and one from outside the northern crater rim), three meta-graywacke, and two phyllite samples from core LB-08A are also presented, providing further insights into the timing of the metamorphism and a possibly related isotopic redistribution of the Bosumtwi crater rocks. Our Rb-Sr and Sm-Nd data show also that the suevites are mixtures of meta-greywacke and phyllite (and possibly a very low amount of granite). A comparison of our new isotopic data with literature data for the Ivory Coast tektites allows to better constrain the parent material of the Ivory Coast tektites (i.e., distal impactites), which is thought to consist of a mixture of metasedimentary rocks (and possibly granite), but with a higher proportion of phyllite (and shale) than the suevites (i.e., proximal impactites). When plotted in a Rb/Sr isochron diagram, the sample data points (n = 29, including literature data) scatter along a regression line, whose slope corresponds to an age of 1846 ± 160 Ma, with an initial Sr isotope ratio of 0.703 ± 0.002. However, due to the extensive alteration of some of the investigated samples and the lithological diversity of the source material, this age, which is in close agreement with a possible "metamorphic age" of ∼ 1.8-1.9 Ga tentatively derived from our U-Pb dating of zircons, is difficult to consider as a reliable metamorphic age. It may perhaps reflect a common ancient source whose Rb-Sr isotope

  16. Protein Crystallization by Anodic Porous Alumina (APA) Template: The Example of Hen Egg White Lysozyme (HEWL)

    OpenAIRE

    Eugenia Pechkova; Nicola Luigi Bragazzi; Claudio Nicolini

    2015-01-01

    In this communication, we report anodic porous alumina (APA) template induced crystallization. The APA nanotemplate was prepared on the glass substrate for the hen egg white lysozyme (HEWL) crystal growth. The changes in the lysozyme crystals morphology, namely in the a/c axis ratio, were observed in the crystal grown by APA nanotemplate, but not in the crystal obtained with classical hanging drop vapor diffusion method, under the same experimental conditions. The comparison of the diffractio...

  17. Non-isothermal Crystallization Kinetics of Poly(L-lactide)

    OpenAIRE

    Li, Suming

    2010-01-01

    International audience The non-isothermal crystallization kinetics of poly(L-lactide) (PLLA) in comparison with a polylactide stereocopolymer (PLA98) containing 98% L-lactyl and 2% D-lactyl units were investigated using differential scanning calorimetry to examine the effect of the configurational structure. Avrami, Ozawa and Liu models were applied to describe the crystallization process. The Avrami analysis exhibited two stages in non-isothermal crystallization, while the Ozawa and Liu m...

  18. Structure and physical properties of single crystal PrCr2Al20 and CeM2Al20 (M=V, Cr): A comparison of compounds adopting the CeCr2Al20 structure type

    International Nuclear Information System (INIS)

    Crystal growth and full structure determination of compounds adopting the CeCr2Al20 structure type, LnTi2Al20 (Ln=La–Pr, Sm, and Yb), LnV2Al20 (Ln=La–Pr, and Sm), and LnCr2Al20 (Ln=La–Pr, Sm, and Yb), are reported. Resistivity, magnetic susceptibility, and heat capacity of flux grown single crystals of the nonmagnetic CeM2Al20 (Ln=Ce, Yb; M=Ti, V) compounds are compared to PrCr2Al20. Of particular interest is PrCr2Al20 which does not show any phase transition down to the lowest temperature of the measurement (400 mK in resistivity measurement and 1.8 K for magnetic susceptibility measurements) and exhibits Kondo behavior at low temperatures. - Graphical abstract: Crystal structure of SmV2Al20 showing the interpenetrating diamond-like samarium network and pyrochlore-like vanadium network. Highlights: ► Single crystals of LnM2Al20 were grown from a molten aluminum flux. ► Magnetic, electrical, and specific heat of single crystal LnM2Al20 are presented. ► PrCr2Al20 exhibits evidence of Kondo effect.

  19. (PCG) Protein Crystal Growth Isocitrate Lysase

    Science.gov (United States)

    1993-01-01

    Comparison of Earth grown and Space grown Isocitrate Lysase crystals. Target enzyme for fungicides. A better understanding of this enzyme should lead to the discovery of more potent fungicides to treat serious crop diseases such as rice blast. It regulates the flow of metabolic intermediates required for cell growth. Principal Investigator was Charles Bugg.

  20. A theory of the nematic liquid crystals

    International Nuclear Information System (INIS)

    A theory of the nematic phase of liquid crystals is presented, taking explicit account of the geometry of the molecule. The three broad peaks of the neutron scattering structure factor are explained. Expressions of the order parameters (average value of Psub(2L)) are given and they can be extracted by comparison with scattering experiments. (author)

  1. Investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium gallium crystals by the Czochralski method

    International Nuclear Information System (INIS)

    Numerical investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium gallium garnet crystals in the same thermal zone and comparison of the obtained results with the experimental data have been performed. It is shown that the difference in the behavior of the crystallization front during growth of the crystals is related to their different transparency in the IR region. In gadolinium gallium garnet crystals, which are transparent to thermal radiation, a crystallization front, strongly convex toward the melt, is formed in the growth stage, which extremely rapidly melts under forced convection. Numerical analysis of this process has been performed within the quasistationary and nonstationary models. At the same time, in terbium gallium garnet crystals, which are characterized by strong absorption of thermal radiation, the phase boundary shape changes fairly smoothly and with a small amplitude. In this case, as the crystal is pulled, the crystallization front tends to become convex toward the crystal bulk.

  2. Pressure cryocooling protein crystals

    Science.gov (United States)

    Kim, Chae Un; Gruner, Sol M.

    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.

  3. Terahertz generation by optical rectification in uniaxial birefringent crystals

    CERN Document Server

    Rowley, J D; Zawilski, K T; Schunemann, P G; Giles, N C; Bristow, A D

    2012-01-01

    The angular dependence of terahertz (THz) emission from birefringent crystals can differ significantly from that of cubic crystals. Here we consider optical rectification in uniaxial birefringent materials, such as chalcopyrite crystals. The analysis is verified in a (110)-cut ZnGeP2 and compared to (zincblende) GaP. Although the structures share the same nonzero second-order tensor elements, birefringence causes the pump pulse polarization to evolve as it propagates through the crystal, resulting in a drastically different angular dependence in chalcopyrite crystals. The analysis is extended to predict the response from {012}- and (114)-cut chalcopyrite crystals, revealing an increase in the maximum emission in comparison to (110)-cut crystals.

  4. Fractional crystallization models for calculating distribution coefficients of chemical elements between magmas and their crystallization products

    International Nuclear Information System (INIS)

    Igneous rock successions can be investigated with respect to their genetic coherence or to the role in fractional crystallization during their generation, respectively, by evaluating element concentration correlations. It is shown that the existence of a linear relation between element concentrations or their logarithms is only a necessary, but not a sufficient condition for fractional crystallization as the dominating factor of graduating element concentrations. The comparison of the slope of such correlation lines with the slope calculated on the basis of the distribution coefficients evaluated by using Schuetze's 18O index reveals whether fractional crystallization is dominant in graduating element concentrations in igneous rocks. Several applications are given. (author)

  5. {sup 1}H and {sup 15}N NMR assignment and solution structure of the SH3 domain of spectrin: Comparison of unrefined and refined structure sets with the crystal structure

    Energy Technology Data Exchange (ETDEWEB)

    Blanco, Francisco J.; Ortiz, Angel R.; Serrano, Luis [European Molecular Biology Laboratory (Germany)

    1997-06-15

    The assignment of the {sup 1}H and {sup 15}Nnuclear magnetic resonance spectra of the Src-homology region 3 domain of chicken brain {alpha}-spectrin has been obtained. A set of solution structures has been determined from distance and dihedral angle restraints,which provide a reasonable representation of the protein structure in solution, as evaluated by a principal component analysis of the global pairwise root-mean-square deviation (rmsd) in a large set of structures consisting of the refined and unrefined solution structures and the crystal structure. The solution structure is well defined, with a lower degree of convergence between the structures in the loop regions than in the secondary structure elements. The average pairwise rmsd between the 15 refined solution structures is 0.71 {+-} 0.13 A for the backbone atoms and 1.43 {+-} 0.14 A for all heavy atoms. The solution structure is basically the same as the crystal structure. The average rmsd between the 15 refined solution structures and the crystal structure is 0.76 A for the backbone atoms and 1.45 {+-} 0.09 A for all heavy atoms. There are, however, small differences probably caused by intermolecular contacts in the crystal structure.

  6. 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.

  7. Aluminum induces cross-resistance of potato to Phytophthora infestans.

    Science.gov (United States)

    Arasimowicz-Jelonek, Magdalena; Floryszak-Wieczorek, Jolanta; Drzewiecka, Kinga; Chmielowska-Bąk, Jagna; Abramowski, Dariusz; Izbiańska, Karolina

    2014-03-01

    The phenomenon of cross-resistance allows plants to acquire resistance to a broad range of stresses after previous exposure to one specific factor. Although this stress-response relationship has been known for decades, the sequence of events that underpin cross-resistance remains unknown. Our experiments revealed that susceptible potato (Solanum tuberosum L. cv. Bintje) undergoing aluminum (Al) stress at the root level showed enhanced defense responses correlated with reduced disease symptoms after leaf inoculation with Phytophthora infestans. The protection capacity of Al to subsequent stress was associated with the local accumulation of H2O2 in roots and systemic activation of salicylic acid (SA) and nitric oxide (NO) dependent pathways. The most crucial Al-mediated changes involved coding of NO message in an enhanced S-nitrosothiol formation in leaves tuned with an abundant SNOs accumulation in the main vein of leaves. Al-induced distal NO generation was correlated with the overexpression of PR-2 and PR-3 at both mRNA and protein activity levels. In turn, after contact with a pathogen we observed early up-regulation of SA-mediated defense genes, e.g. PR1, PR-2, PR-3 and PAL, and subsequent disease limitation. Taken together Al exposure induced distal changes in the biochemical stress imprint, facilitating more effective responses to a subsequent pathogen attack. PMID:24346311

  8. Aluminum induces lipid peroxidation and aggregation of human blood platelets

    Directory of Open Access Journals (Sweden)

    Neiva T.J.C.

    1997-01-01

    Full Text Available Aluminum (Al3+ intoxication is thought to play a major role in the development of Alzheimer's disease and in certain pathologic manifestations arising from long-term hemodialysis. Although the metal does not present redox capacity, it can stimulate tissue lipid peroxidation in animal models. Furthermore, in vitro studies have revealed that the fluoroaluminate complex induces diacylglycerol formation, 43-kDa protein phosphorylation and aggregation. Based on these observations, we postulated that Al3+-induced blood platelet aggregation was mediated by lipid peroxidation. Using chemiluminescence (CL of luminol as an index of total lipid peroxidation capacity, we established a correlation between lipid peroxidation capacity and platelet aggregation. Al3+ (20-100 µM stimulated CL production by human blood platelets as well as their aggregation. Incubation of the platelets with the antioxidants nor-dihydroguaiaretic acid (NDGA (100 µM and n-propyl gallate (NPG (100 µM, inhibitors of the lipoxygenase pathway, completely prevented CL and platelet aggregation. Acetyl salicylic acid (ASA (100 µM, an inhibitor of the cyclooxygenase pathway, was a weaker inhibitor of both events. These findings suggest that Al3+ stimulates lipid peroxidation and the lipoxygenase pathway in human blood platelets thereby causing their aggregation

  9. Aluminum induces lipid peroxidation and aggregation of human blood platelets

    OpenAIRE

    T.J.C. Neiva; D.M. Fries; Monteiro, H. P.; E.A. D'Amico; D.A.F. Chamone

    1997-01-01

    Aluminum (Al3+) intoxication is thought to play a major role in the development of Alzheimer's disease and in certain pathologic manifestations arising from long-term hemodialysis. Although the metal does not present redox capacity, it can stimulate tissue lipid peroxidation in animal models. Furthermore, in vitro studies have revealed that the fluoroaluminate complex induces diacylglycerol formation, 43-kDa protein phosphorylation and aggregation. Based on these observations, we postulated t...

  10. Growth of KH2PO4 crystals at constant temperature and supersaturation. Final report, October 20, 1980-October 20, 1981

    International Nuclear Information System (INIS)

    A large three-zone crystallizer system was constructed and successfully operated for growing KH2PO4 single crystals. Under conditions of constant crystallization temperature and supersaturation, growth rates exceding 5 mm per day were demonstrated for KH2PO4 crystals of 5 x 5 cm cross section. The optical quality of these crystals was equivalent to that of crystals grown at rates presently considered as state-of-the-art (approx. 1 mm/day). Sample crystals were supplied for comparison testing. The three-zone system appears to be ideally suitable for growth of large-diameter KH2PO4 crystals for the Laser Fusion Program

  11. Crystallization and crystal properties of squid rhodopsin

    OpenAIRE

    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.

  12. Comparison between Double Crystals X-ray Diffraction and Micro-Raman Measurement on Composition Determination of High Ge Content Si1-xGex Layer Epitaxied on Si Substrate

    Institute of Scientific and Technical Information of China (English)

    Lei ZHAO; Yuhua ZUO; Buwen CHENG; Jinzhong YU; Qiming WANG

    2006-01-01

    It is important to acquire the composition of Si1-xGex layer, especially that with high Ge content, epitaxied on Si substrate. Two nondestructive examination methods, double crystals X-ray diffraction(DCXRD)and micro-Raman measurement, were introduced comparatively to determine x value in Si1-xGex layer, which show that while the two methods are consistent with each other when x is low, the results obtained from double crystals X-ray diffraction are not credible due to the large strain relaxation occurring in Si1-xGex layers when Ge content is higher than about 20%. Micro-Raman measurement is more appropriate for determining high Ge content than DCXRD.

  13. Imatinib (Gleevec@) conformations observed in single crystals, protein-Imatinib co-crystals and molecular dynamics: Implications for drug selectivity

    Science.gov (United States)

    Golzarroshan, B.; Siddegowda, M. S.; Li, Hong qi; Yathirajan, H. S.; Narayana, B.; Rathore, R. S.

    2012-06-01

    Structure and dynamics of the Leukemia drug, Imatinib, were examined using X-ray crystallography and molecular dynamics studies. Comparison of conformations observed in single crystals with several reported co-crystals of protein-drug complexes suggests existence of two conserved conformations of Imatinib, extended and compact (or folded), corresponding to two binding modes of interaction with the receptor. Furthermore, these conformations are conserved throughout a dynamics simulation. The present study attempts to draw a parallel on conformations and binding patterns of interactions, obtained from small-molecule single-crystal and macromolecule co-crystal studies, and provides structural insights for understanding the high selectivity of this drug molecule.

  14. 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.

  15. Crystallization from Gels

    Science.gov (United States)

    Narayana Kalkura, S.; Natarajan, Subramanian

    Among the various crystallization techniques, crystallization in gels has found wide applications in the fields of biomineralization and macromolecular crystallization in addition to crystallizing materials having nonlinear optical, ferroelectric, ferromagnetic, and other properties. Furthermore, by using this method it is possible to grow single crystals with very high perfection that are difficult to grow by other techniques. The gel method of crystallization provides an ideal technique to study crystal deposition diseases, which could lead to better understanding of their etiology. This chapter focuses on crystallization in gels of compounds that are responsible for crystal deposition diseases. The introduction is followed by a description of the various gels used, the mechanism of gelling, and the fascinating phenomenon of Liesegang ring formation, along with various gel growth techniques. The importance and scope of study on crystal deposition diseases and the need for crystal growth experiments using gel media are stressed. The various crystal deposition diseases, viz. (1) urolithiasis, (2) gout or arthritis, (3) cholelithiasis and atherosclerosis, and (4) pancreatitis and details regarding the constituents of the crystal deposits responsible for the pathological mineralization are discussed. Brief accounts of the theories of the formation of urinary stones and gallstones and the role of trace elements in urinary stone formation are also given. The crystallization in gels of (1) the urinary stone constituents, viz. calcium oxalate, calcium phosphates, uric acid, cystine, etc., (2) the constituents of the gallstones, viz. cholesterol, calcium carbonate, etc., (3) the major constituent of the pancreatic calculi, viz., calcium carbonate, and (4) cholic acid, a steroidal hormone are presented. The effect of various organic and inorganic ions, trace elements, and extracts from cereals, herbs, and fruits on the crystallization of major urinary stone and gallstone

  16. 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.

  17. Kinetics of barium sulphate reaction crystallization in crystallizers with internal circulation

    Directory of Open Access Journals (Sweden)

    J. Koralewska

    2008-06-01

    Full Text Available Kinetic calculation results describing the observed nucleation and growth rates of barium sulphate crystals precipitated in an integrated reaction-crystallization process in a barium sulphate-ammonium chloride-water system are presented and analyzed. The scope of experiments included two continuous model DTM-type crystallizers (Draft Tube Magma with internal circulation of the suspension forced by a liquid jet-pump device responsible for stable and intensive enough ascending/descending flow of BaSO4 crystal magma in a mixing chamber. For comparison purposes the experimental data corresponding to a continuous DT (Draft Tube crystallizer with propeller agitator are presented and discussed. The various types of laboratory crystallizers used were fed with concentrated water solution of barium chloride (of 10 or 24 mass % and - in a stoichiometric proportion - crystalline ammonium sulphate, assuming isothermal (348 K and hydrodynamic (average residence time of suspension in a crystallizer: 900 s process conditions. The observed nucleation and growth rates of barium sulphate crystals were estimated on the basis of crystal size distributions (CSDs using convenient calculation scheme derived for an MSMPR (Mixed Suspension Mixed Product Removal model approach. Considering the experimental population density distribution courses, a size-dependent growth (SDG phenomenon was taken into account in the kinetic calculations. Five SDG kinetic models recommended in the accessible literature were used for kinetic parameter values estimation. It was proved statistically, that Rojkowski’s two SDG models (hyperbolic and exponential best suit for our own experimental data description. The experimental data presented can be practically applied for improving the constructions of liquid jet-pump DTM crystallizers recommended for reaction crystallization of sparingly soluble inorganic salts (especially for high concentrations of reaction substrates in the modern

  18. Protein Crystal Based Nanomaterials

    Science.gov (United States)

    Bell, Jeffrey A.; VanRoey, Patrick

    2001-01-01

    This is the final report on a NASA Grant. It concerns a description of work done, which includes: (1) Protein crystals cross-linked to form fibers; (2) Engineering of protein to favor crystallization; (3) Better knowledge-based potentials for protein-protein contacts; (4) Simulation of protein crystallization.

  19. Artistic Crystal Creations

    Science.gov (United States)

    Lange, Catherine

    2008-01-01

    In this inquiry-based, integrative art and science activity, Grade 5-8 students use multicolored Epsom salt (magnesium sulfate) crystallizing solutions to reveal beautiful, cylindrical, 3-dimensional, needle-shaped structures. Through observations of the crystal art, students analyze factors that contribute to crystal size and formation, compare…

  20. Protein crystallization with paper

    Science.gov (United States)

    Matsuoka, Miki; Kakinouchi, Keisuke; Adachi, Hiroaki; Maruyama, Mihoko; Sugiyama, Shigeru; Sano, Satoshi; Yoshikawa, Hiroshi Y.; Takahashi, Yoshinori; Yoshimura, Masashi; Matsumura, Hiroyoshi; Murakami, Satoshi; Inoue, Tsuyoshi; Mori, Yusuke; Takano, Kazufumi

    2016-05-01

    We developed a new protein crystallization method that incorporates paper. A small piece of paper, such as facial tissue or KimWipes, was added to a drop of protein solution in the traditional sitting drop vapor diffusion technique, and protein crystals grew by incorporating paper. By this method, we achieved the growth of protein crystals with reducing osmotic shock. Because the technique is very simple and the materials are easy to obtain, this method will come into wide use for protein crystallization. In the future, it could be applied to nanoliter-scale crystallization screening on a paper sheet such as in inkjet printing.

  1. Suitability of linear quadrupole ion traps for large Coulomb crystals

    CERN Document Server

    Tabor, D A; Odom, B

    2011-01-01

    Growing and studying large Coulomb crystals, composed of tens to hundreds of thousands of ions, in linear quadrupole ion traps presents new challenges for trap implementation. We consider several trap designs, first comparing the total driven micromotion amplitude as a function of location within the trapping volume; total micromotion is an important point of comparison since it can limit crystal size by transfer of radiofrequency drive energy into thermal energy. We also compare the axial component of micromotion, which leads to first-order Doppler shifts along the preferred spectroscopy axis in precision measurements on large Coulomb crystals. Finally, we compare trapping potential anharmonicity, which can induce nonlinear resonance heating by shifting normal mode frequencies onto resonance as a crystal grows. We apply a non-deforming crystal approximation for simple calculation of these anharmonicity-induced shifts, allowing a straightforward estimation of when crystal growth can lead to excitation of diff...

  2. Single crystal U–Pb zircon age and Sr–Nd isotopic composition of impactites from the Bosumtwi impact structure, Ghana: Comparison with country rocks and Ivory Coast tektites

    OpenAIRE

    Ferrière, Ludovic; Koeberl, Christian; Thöni, Martin; Liang, Chen

    2010-01-01

    The 1.07 Myr old Bosumtwi impact structure (Ghana), excavated in 2.1–2.2 Gyr old supracrustal rocks of the Birimian Supergroup, was drilled in 2004. Here, we present single crystal U–Pb zircon ages from a suevite and two meta-graywacke samples recovered from the central uplift (drill core LB-08A), which yield an upper Concordia intercept age of ca. 2145 ± 82 Ma, in very good agreement with previous geochronological data for the West African Craton rocks in Ghana. Whole rock Rb–Sr and Sm–Nd is...

  3. Protein Crystal Growth

    Science.gov (United States)

    2003-01-01

    In order to rapidly and efficiently grow crystals, tools were needed to automatically identify and analyze the growing process of protein crystals. To meet this need, Diversified Scientific, Inc. (DSI), with the support of a Small Business Innovation Research (SBIR) contract from NASA s Marshall Space Flight Center, developed CrystalScore(trademark), the first automated image acquisition, analysis, and archiving system designed specifically for the macromolecular crystal growing community. It offers automated hardware control, image and data archiving, image processing, a searchable database, and surface plotting of experimental data. CrystalScore is currently being used by numerous pharmaceutical companies and academic and nonprofit research centers. DSI, located in Birmingham, Alabama, was awarded the patent Method for acquiring, storing, and analyzing crystal images on March 4, 2003. Another DSI product made possible by Marshall SBIR funding is VaporPro(trademark), a unique, comprehensive system that allows for the automated control of vapor diffusion for crystallization experiments.

  4. Welding Molecular Crystals.

    Science.gov (United States)

    Adolf, Cyril R R; Ferlay, Sylvie; Kyritsakas, Nathalie; Hosseini, Mir Wais

    2015-12-16

    Both for fundamental and applied sciences, the design of complex molecular systems in the crystalline phase with strict control of order and periodicity at both microscopic and macroscopic levels is of prime importance for development of new solid-state materials and devices. The design and fabrication of complex crystalline systems as networks of crystals displaying task-specific properties is a step toward smart materials. Here we report on isostructural and almost isometric molecular crystals of different colors, their use for fabrication of core-shell crystals, and their welding by 3D epitaxial growth into networks of crystals as single-crystalline entities. Welding of crystals by self-assembly processes into macroscopic networks of crystals is a powerful strategy for the design of hierarchically organized periodic complex architectures composed of different subdomains displaying targeted characteristics. Crystal welding may be regarded as a first step toward the design of new hierarchically organized complex crystalline systems. PMID:26581391

  5. Crystal structure of cesium salt of Fe(3) thiosemicarbazonate complex at 298 and 103 K. Comparison of geometrical parameters of Fe3S2O2N2 octahedral coordination fragment in high- and low-spin complexes

    International Nuclear Information System (INIS)

    The crystal structure of a high spin cesium salt of the Fe(3), thiosemicarbazonate complex, Cs[Fe(tsa)2], (tsa-salicyl aldehyde thiosemicarbazone) at room temperature and 103 K, is determined. The parameters of the rhombic cell are: a=15, 285(3), b=13.402(4), c=9.449(8)A at 298 K and a=15.161(3), b=13.340(3), c=9.394(7)A at 103 K. The space group is Pna21, Z=4, the final values of R-factors are 0.054 (298 K, 1232 reflections) and 0.041 (103 K, 1597 reflections) taking into account the absorption of X-rays using the method of calculating corrections according to the crystal form and the anomalous scattering of Cs, Fe, S atoms. The structure is built of Cs+ cations and complex anions [Fe(tsa)2]-. The specific intermolecular interactions are absent. Fe-S and Fe-N bond lengths and the values of some inner angles of the coordination polyhedron of iron atom are taken as structural characteristics during the diagnostics of the Fe(3) ion spin state in thiosemicarbazonate complexes

  6. The contribution of polystyrene nanospheres towards the crystallization of proteins.

    Directory of Open Access Journals (Sweden)

    Johanna M Kallio

    Full Text Available BACKGROUND: Protein crystallization is a slow process of trial and error and limits the amount of solved protein structures. Search of a universal heterogeneous nucleant is an effort to facilitate crystallizability of proteins. METHODOLOGY: The effect of polystyrene nanospheres on protein crystallization were tested with three commercial proteins: lysozyme, xylanase, xylose isomerase, and with five research target proteins: hydrophobins HFBI and HFBII, laccase, sarcosine dimethylglycine N-methyltransferase (SDMT, and anti-testosterone Fab fragment 5F2. The use of nanospheres both in screening and as an additive for known crystallization conditions was studied. In screening, the addition of an aqueous solution of nanosphere to the crystallization drop had a significant positive effect on crystallization success in comparison to the control screen. As an additive in hydrophobin crystallization, the nanospheres altered the crystal packing, most likely due to the amphiphilic nature of hydrophobins. In the case of laccase, nanospheres could be used as an alternative for streak-seeding, which insofar had remained the only technique to produce high-diffracting crystals. With methyltransferase SDMT the nanospheres, used also as an additive, produced fewer, larger crystals in less time. Nanospheres, combined with the streak-seeding method, produced single 5F2 Fab crystals in shorter equilibration times. CONCLUSIONS: All in all, the use of nanospheres in protein crystallization proved to be beneficial, both when screening new crystallization conditions to promote nucleation and when used as an additive to produce better quality crystals, faster. The polystyrene nanospheres are easy to use, commercially available and close to being inert, as even with amphiphilic proteins only the crystal packing is altered and the nanospheres do not interfere with the structure and function of the protein.

  7. Revisiting the blind tests in crystal structure prediction: accurate energy ranking of molecular crystals.

    Science.gov (United States)

    Asmadi, Aldi; Neumann, Marcus A; Kendrick, John; Girard, Pascale; Perrin, Marc-Antoine; Leusen, Frank J J

    2009-12-24

    In the 2007 blind test of crystal structure prediction hosted by the Cambridge Crystallographic Data Centre (CCDC), a hybrid DFT/MM method correctly ranked each of the four experimental structures as having the lowest lattice energy of all the crystal structures predicted for each molecule. The work presented here further validates this hybrid method by optimizing the crystal structures (experimental and submitted) of the first three CCDC blind tests held in 1999, 2001, and 2004. Except for the crystal structures of compound IX, all structures were reminimized and ranked according to their lattice energies. The hybrid method computes the lattice energy of a crystal structure as the sum of the DFT total energy and a van der Waals (dispersion) energy correction. Considering all four blind tests, the crystal structure with the lowest lattice energy corresponds to the experimentally observed structure for 12 out of 14 molecules. Moreover, good geometrical agreement is observed between the structures determined by the hybrid method and those measured experimentally. In comparison with the correct submissions made by the blind test participants, all hybrid optimized crystal structures (apart from compound II) have the smallest calculated root mean squared deviations from the experimentally observed structures. It is predicted that a new polymorph of compound V exists under pressure. PMID:19950907

  8. Polymer semiconductor crystals

    Directory of Open Access Journals (Sweden)

    Jung Ah Lim

    2010-05-01

    Full Text Available One of the long-standing challenges in the field of polymer semiconductors is to figure out how long interpenetrating and entangled polymer chains self-assemble into single crystals from the solution phase or melt. The ability to produce these crystalline solids has fascinated scientists from a broad range of backgrounds including physicists, chemists, and engineers. Scientists are still on the hunt for determining the mechanism of crystallization in these information-rich materials. Understanding the theory and concept of crystallization of polymer semiconductors will undoubtedly transform this area from an art to an area that will host a bandwagon of scientists and engineers. In this article we describe the basic concept of crystallization and highlight some of the advances in polymer crystallization from crystals to nanocrystalline fibers.

  9. Macromolecular crystallization in microgravity

    Energy Technology Data Exchange (ETDEWEB)

    Snell, Edward H [Biophysics Group, NASA Marshall Space Flight Center, Code XD42, Huntsville, AL 35812 (United States); Helliwell, John R [Department of Chemistry, The University of Manchester, Manchester, M13 9PL (United Kingdom)

    2005-04-01

    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. Holographic liquid crystal devices

    OpenAIRE

    Pavani, Kotakonda, (Thesis)

    2009-01-01

    Liquid crystals have become natural candidates for use in electro-optic devices for their ability to change the orientation of the director with the application of an electric field, and exhibiting large range of refractive index. The aim of the work presented in this thesis is to fabricate liquid crystal optoelectronic devices such as electrically switchable liquid crystal diffraction gratings and polarization rotators by exploiting the holographic surface relief effect in photopolymer and b...

  11. Ion Coulomb Crystals

    CERN Document Server

    Thompson, Richard C

    2014-01-01

    Ion Coulomb crystals (ICC), formed by atomic ions at low temperatures in radiofrequency and Penning ion traps, are structures that have remarkable properties and many applications. Images of Coulomb crystals are striking and reveal the crystal structure, which arises from a balance between the trapping forces acting on the ions and their mutual Coulomb repulsion. Applications of these structures range from frequency standards and quantum simulation through to measurement of the cross sections of chemical reactions of ions.

  12. Mercury iodide crystal growth

    Science.gov (United States)

    Cadoret, R.

    1982-01-01

    The purpose of the Mercury Iodide Crystal Growth (MICG) experiment is the growth of near-perfect single crystals of mercury Iodide (HgI2) in a microgravity environment which will decrease the convection effects on crystal growth. Evaporation and condensation are the only transformations involved in this experiment. To accomplish these objectives, a two-zone furnace will be used in which two sensors collect the temperature data (one in each zone).

  13. Photonic Crystal Waveguide Fabrication

    OpenAIRE

    Høvik, Jens

    2012-01-01

    This research is entirely devoted to the study and fabrication of structures with periodic dielectric constants, also known as photonic crystals (PhCs). These structures show interesting dispersion characteristics which give them a range of prohibited frequencies that are not allowed to propagate within the crystal. This property makes them suited for a wide array of photonic-based components. One-dimensional photonic crystals are already commercialized and are of widespread use in for exampl...

  14. CMS lead tungstate crystals

    CERN Multimedia

    Laurent Guiraud

    2000-01-01

    These crystals are made from lead tungstate, a crystal that is as clear as glass yet with nearly four times the density. They have been produced in Russia to be used as scintillators in the electromagnetic calorimeter on the CMS experiment, part of the LHC project at CERN. When an electron, positron or photon passes through the calorimeter it will cause a cascade of particles that will then be absorbed by these scintillating crystals, allowing the particle's energy to be measured.

  15. Crystallization 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...

  16. 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...

  17. Phononic crystal devices

    Science.gov (United States)

    El-Kady, Ihab F.; Olsson, Roy H.

    2012-01-10

    Phononic crystals that have the ability to modify and control the thermal black body phonon distribution and the phonon component of heat transport in a solid. In particular, the thermal conductivity and heat capacity can be modified by altering the phonon density of states in a phononic crystal. The present invention is directed to phononic crystal devices and materials such as radio frequency (RF) tags powered from ambient heat, dielectrics with extremely low thermal conductivity, thermoelectric materials with a higher ratio of electrical-to-thermal conductivity, materials with phononically engineered heat capacity, phononic crystal waveguides that enable accelerated cooling, and a variety of low temperature application devices.

  18. Tunable plasmonic crystal

    Science.gov (United States)

    Dyer, Gregory Conrad; Shaner, Eric A.; Reno, John L.; Aizin, Gregory

    2015-08-11

    A tunable plasmonic crystal comprises several periods in a two-dimensional electron or hole gas plasmonic medium that is both extremely subwavelength (.about..lamda./100) and tunable through the application of voltages to metal electrodes. Tuning of the plasmonic crystal band edges can be realized in materials such as semiconductors and graphene to actively control the plasmonic crystal dispersion in the terahertz and infrared spectral regions. The tunable plasmonic crystal provides a useful degree of freedom for applications in slow light devices, voltage-tunable waveguides, filters, ultra-sensitive direct and heterodyne THz detectors, and THz oscillators.

  19. Suitability of linear quadrupole ion traps for large Coulomb crystals

    OpenAIRE

    Tabor, D. A.; Rajagopal, V.; Lin, Y-W.; Odom, B.

    2011-01-01

    Growing and studying large Coulomb crystals, composed of tens to hundreds of thousands of ions, in linear quadrupole ion traps presents new challenges for trap implementation. We consider several trap designs, first comparing the total driven micromotion amplitude as a function of location within the trapping volume; total micromotion is an important point of comparison since it can limit crystal size by transfer of radiofrequency drive energy into thermal energy. We also compare the axial co...

  20. Some results of simulation on radiation effects in crystals

    International Nuclear Information System (INIS)

    Simulations concerning radiation in oriented silicon and tungsten crystals of different thicknesses are developed. Conditions are those of experiments done at Kharkov (Ukraine) and Tomsk (Russia) with electron beams in the 1 GeV range. Systematic comparisons between experimental and simulated spectra associated to real spectrum, radiation energy and angular distribution of the photons are developed. The ability of the simulation program to describe crystal effects in the considered energy range is analysed. (author) 11 refs.; 8 figs

  1. INTERFACIAL MASS TRANSPORT IN OXIDE CRYSTAL GROWTH

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ A space high temperature in situobservation instrument (SHITISOI) is dedicated to visualize and record the whole growth process of oxide crystal in high temperature melts and solutions. Model experiments using transparent liquids such as KNbO3,Li2B4O7+KNbO3 were chosen to investigate effects of interracial mass transport in oxide crystal growth. For the scaling of the coupled velocity, heat and concentration fields in KNbO3 crystal growth, a rotating crystal growth process was performed and the widths of interfacial concentration, heat and momentum transition zones (The "boundary layers") are obtained, which are 7.5×10-a, 8.6×10-2 and 4.4×10-1 cm,respectively. Hence one can expect that interfacial concentration gradient will be confined to a narrow layer and in region of major concentration change at the in terface. In order to study a mechanism based on the interfacial mass transport resulting from hydrodynamics, the growth of KNbO3 grain in high temperature Li2B4O7 and KNbO3 solutin was studied. The result shows that the pivotal feature in the KNbO3 crystal growth is the initiated by KNbO3 solute surface tension gra dient which is caused by the slow diffusion of KNbO3 solutes. Direct comparison of the model predictions and experimental observed phenomena demonstrate the predictive capability of this model.

  2. Recent results from Crystal Barrel

    CERN Document Server

    Doser, Michael

    2000-01-01

    The Crystal Barrel detector has collected data on antiproton annihilation on Hydrogen and Deuterium at rest and at momenta up to 1940 MeV/c, accumulating a total of 600 M events with the goal of studying meson spectroscopy and searching for non-qbarq states. This large amount of data has allowed high statistics studies of exclusive final states produced under various initial conditions. Comparisons between different initial and final states greatly constrain the interpretation of these data sets. In particular, the requirement of consistency between fits of 3-body final state Dalitz plots is a powerful tool in the search for non-standard model resonances [1]. More recently, the study of the same Dalitz plot produced from antiproton annihilation on liquid and gaseous hydrogen, on deuterium or on liquid hydrogen at different center-of-mass energies has extended this approach to higher mass resonances.

  3. Crystal structure of levomepromazine maleate

    Directory of Open Access Journals (Sweden)

    Gyula Tamás Gál

    2016-05-01

    Full Text Available The asymmetric unit of the title salt, C19H25N2OS+·C4H3O4− [systematic name: (S-3-(2-methoxyphenothiazin-10-yl-N,N,2-trimethylpropanaminium hydrogen maleate], comprises two (S-levomepromazine cations and two hydrogen maleate anions. The conformations of the two cations are similar. The major difference relates to the orientation of the methoxy substituent at the phenothiazine ring system. The crystal components form a three-dimensional supramolecular network via N—H...O, C—H...O and C—H...π interactions. A comparison of the conformations of the levomepromazine cations with those of the neutral molecule and similar protonated molecules reveals significant conformational flexibility of the phenothiazine ring system and the substituent at the phenothiazine N atom.

  4. 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.

  5. Thermotropic Ionic Liquid Crystals

    OpenAIRE

    Sabine Laschat; Axenov, Kirill V

    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.

  6. Crystals in the LHC

    CERN Multimedia

    Antonella Del Rosso

    2012-01-01

    Bent crystals can be used to deflect charged particle beams. Their use in high-energy accelerators has been investigated for almost 40 years. Recently, a bent crystal was irradiated for the first time in the HiRadMat facility with an extreme particle flux, which crystals would have to withstand in the LHC. The results were very encouraging and confirmed that this technology could play a major role in increasing the beam collimation performance in future upgrades of the machine.   UA9 bent crystal tested with a laser. Charged particles interacting with a bent crystal can be trapped in channelling states and deflected by the atomic planes of the crystal lattice (see box). The use of bent crystals for beam manipulation in particle accelerators is a concept that has been well-assessed. Over the last three decades, a large number of experimental findings have contributed to furthering our knowledge and improving our ability to control crystal-particle interactions. In modern hadron colliders, su...

  7. Photonic Crystal Fiber Attenuator

    Institute of Scientific and Technical Information of China (English)

    Joo Beom Eom; Hokyung Kim; Jinchae Kim; Un-Chul Paek; Byeong Ha Lee

    2003-01-01

    We propose a novel fiber attenuator based on photonic crystal fibers. The difference in the modal field diameters of a conventional single mode fiber and a photonic crystal fiber was used. A variable optical attenuator was also achieved by applying macro-bending on the PCF part of the proposed attenuator

  8. Silicon crystal under bending

    International Nuclear Information System (INIS)

    The mechanical behavior of a silicon crystal under bending is investigated. For a crystal of length 30 mm and thickness 3 mm, to achieve the specified bend angle of 0.64 mrad, the appropriate angle of the aluminum punches is 0.96 mrad

  9. 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....

  10. 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…

  11. Superconducting photonic crystals

    OpenAIRE

    Berman, Oleg L.; Lozovik, Yurii E.; Eiderman, Sergey L.; Coalson, Rob D.

    2006-01-01

    The band structure of a novel type of photonic crystal with superconducting constituent elements is calculated numerically via a plane wave expansion. The density of states and the dependence of the width of the photonic gap on the filling factor is analyzed for a two-dimensional photonic crystal consisting of an infinite array of parallel superconducting cylinders.

  12. Limiting pump intensity for sulfur-doped gallium selenide crystals

    International Nuclear Information System (INIS)

    High optical quality undoped and sulfur-doped gallium selenide crystals were grown from melts by the modified vertical Bridgman method. Detailed study of the damage produced under femtosecond pulse exposure has shown that evaluation of the damage threshold by visual control is unfounded. Black matter spots produced on crystal surfaces do not noticeably decrease either its transparency or its frequency conversion efficiency as opposed to real damage identified as caked well-cohesive gallium structures. For the first time it was demonstrated that optimally sulfur-doped gallium selenide crystal possesses the highest resistivity to optical emission (about four times higher in comparison with undoped gallium selenide)

  13. Functional substitution of coordination polyhedron in crystal structure of silicates

    Institute of Scientific and Technical Information of China (English)

    叶大年; 马哲生; 赫伟; 李哲; 施倪承; D.Pushcharovsky

    2002-01-01

    On the bases of the study of comparative crystal chemistry of silicates it has been concluded that the octahedra and square pyramids of Ti-0 and Zr-O play functional role of tetrahedra of Si-O in the construction of crystal structures. Therefore, those silicates may be named titano-and zircono-silicates. Because of the functional similarity of coordination polyhedra, the structures of cristobalite and feldspar have been compared with those of perovskite and garnet, respectively. As a new concept, the functional replacement of tetrahedra by octahedra and/or pyramids is defined by the authors of this paper for favorable comparison of relative crystal structures.

  14. Active Photonic Crystal Waveguides

    DEFF Research Database (Denmark)

    Ek, Sara

    This thesis deals with the fabrication and characterization of active photonic crystal waveguides, realized in III-V semiconductor material with embedded active layers. The platform offering active photonic crystal waveguides has many potential applications. One of these is a compact photonic...... crystal semiconductor optical amplier. As a step towards such a component, photonic crystal waveguides with a single quantum well, 10 quantum wells and three layers of quantum dots are fabricated and characterized. An experimental study of the amplied spontaneous emission and a implied transmission are...... presented in this thesis. A variation of photonic crystal design parameters are used leading to a spectral shift of the dispersion, it is veried that the observed effects shift accordingly. An enhancement of the amplified spontaneous emission was observed close to the band edge, where light is slowed down...

  15. Optically Anomalous Crystals

    CERN Document Server

    Shtukenberg, Alexander; Kahr, Bart

    2007-01-01

    Optical anomalies in crystals are puzzles that collectively constituted the greatest unsolved problems in crystallography in the 19th Century. The most common anomaly is a discrepancy between a crystal’s symmetry as determined by its shape or by X-ray analysis, and that determined by monitoring the polarization state of traversing light. These discrepancies were perceived as a great impediment to the development of the sciences of crystals on the basis of Curie’s Symmetry Principle, the grand organizing idea in the physical sciences to emerge in the latter half of the 19th Century. Optically Anomalous Crystals begins with an historical introduction covering the contributions of Brewster, Biot, Mallard, Brauns, Tamman, and many other distinguished crystallographers. From this follows a tutorial in crystal optics. Further chapters discuss the two main mechanisms of optical dissymmetry: 1. the piezo-optic effect, and 2. the kinetic ordering of atoms. The text then tackles complex, inhomogeneous crystals, and...

  16. Crystallization phenomena of isotactic polystyrene

    NARCIS (Netherlands)

    Lemstra, Peter Jan

    1975-01-01

    In this thesis the crystallization behavior of isotactic polystyrene has been described. The kinetics of the crystallization process and the crystalline structure were studied both for crystallization in the bulk and from dilute solutions. ... Zie Summary

  17. Compact and broadband waveguide taper based on partial bandgap photonic crystals

    Institute of Scientific and Technical Information of China (English)

    Jin Hou; Dingshan Gao; Huaming Wu; Zhiping Zhou

    2009-01-01

    Partial bandgap characteristics of parallelogram lattice photonic crystals are proposed to suppress the radiation modes in a compact dielectric waveguide taper so as to obtain high transmittance in a large wavelength range. Band structure of the photonic crystals shows that there exists a partial bandgap. The photonic crystals with partial bandgap are then used as the cladding of a waveguide taper to reduce the radiation loss efficiently. In comparison with the conventional dielectric taper and the complete bandgap photonic crystal taper, the partial bandgap photonic crystal taper has a high transmittance of above 85% with a wide band of 170 nm.

  18. Measurements of coherent interactions of 400 GeV protons in silicon bent crystals

    International Nuclear Information System (INIS)

    Within UA9 Collaboration bent silicon crystals has been irradiated by 400 GeV proton beams at the H8 line of the CERN SPS North Area. Proton–crystal interactions were investigated by analyzing the particle trajectories hitting the crystal. 26 crystals were tested and 10 of them used to extract key crystal properties, such as bending angle, channeling efficiency and so on. A statistical analysis of the results is presented. The results provide experimental data to be used for an exhaustive comparison with simulation routines

  19. Computation of LACBED images from bi-crystals using reciprocity. Part 1 Rigid-body displacements between parallel crystals

    International Nuclear Information System (INIS)

    A new method for the rapid generation of high resolution bicrystal LACBED images is described, which uses reciprocity to generate the second-crystal transmission function for a specific doubly-transmitted beam. As a result, sets of bright-field or specific dark-field LACBED images can readily be generated for sets inter-crystal displacements, to allow comparison with experimental results. In Part I we describe results obtained for pure translations between bi-crystals pairs, while in Part II we describe the method for bi-crystals incorporating relative rotations as well as translations. It is envisaged that this technique will be useful for the body semi-conductor crystal pair interfaces, and metal-alloy grain boundaries, in particular. (authors). 16 refs., 6 figs

  20. Photonic Crystal Laser Accelerator Structures

    OpenAIRE

    Cowan, Benjamin; Javanmard, Mehdi; Siemann, Robert H.

    2003-01-01

    Photonic crystals have great potential for use as laser-driven accelerator structures. A photonic crystal is a dielectric structure arranged in a periodic geometry. Like a crystalline solid with its electronic band structure, the modes of a photonic crystal lie in a set of allowed photonic bands. Similarly, it is possible for a photonic crystal to exhibit one or more photonic band gaps, with frequencies in the gap unable to propagate in the crystal. Thus photonic crystals can confine an optic...

  1. Origin of platy calcite crystals in hot-spring deposits in the Kenya Rift Valley

    Energy Technology Data Exchange (ETDEWEB)

    Jones, B. [Univ. of Alberta, Edmonton, Alberta (Canada). Dept. of Earth and Atmospheric Sciences; Renault, R.W. [Univ. of Saskatchewan, Saskatoon, Saskatchewan (Canada). Dept. of Geological Sciences

    1998-09-01

    Platy calcite crystals, which have their c axis parallel to their shortest length axis, are common components of travertine deposits found around some hot springs in the Kenya Rift Valley. They are composite crystals formed of numerous paper-thin subcrystals. Individual plates allowed to grow without obstruction develop a hexagonal motif. The Kenyan crystals typically form in hot (>75 C) waters that have a low Ca content (<10 mg/l), a high CO{sub 2} content, and a high rate of CO{sub 2} degassing. At Chemurkeu, aggregates of numerous small platy crystals collectively form lattice crystals that superficially resemble ray crystals. The walls of the lattice crystals are formed of large platy crystals that have their long and intermediate length axes aligned parallel to the plane of the long axis of the lattice crystal. Internally, the lattice crystals are formed of small platy calcite crystals arranged in a boxlike pattern that creates the appearance of a lattice when viewed in thin section. Lattice crystals are highly porous, with each pore being enclosed by platy crystals. At Lorusio, travertines are mainly formed of pseudodentrites that are constructed by numerous small platy crystals attached to a main stem which is a large platy crystal that commonly curves along its long axis. The pseudodentrites are the main construction blocks in ledges and lilypads that form in the vent pool and spring outflow channels, where the water is too hot for microbes other than hyperthermophiles. The platy calcite crystals in the Kenyan travertines are morphologically similar to platy calcite crystals that form as scale in pipes in the geothermal fields of New Zealand and hydrothermal angel wing calcite from the La Fe mine in Mexico. Comparison of the Kenyan and New Zealand crystals indicates that platy calcite crystals form from waters with a low Ca{sup 2+} content and a high CO{sub 3}/Ca ratio due to rapid rates of CO{sub 2} degassing.

  2. An approach to engineer paracetamol crystals by antisolvent crystallization technique in presence of various additives for direct compression.

    Science.gov (United States)

    Kaialy, Waseem; Larhrib, Hassan; Chikwanha, Brian; Shojaee, Saeed; Nokhodchi, Ali

    2014-04-10

    Paracetamol is a popular over-the-counter analgesic and a challenging model drug due to its poor technological and biopharmaceutical properties such as flowability, compressibility, compactibility and wettability. This work was aimed to alter the crystal habit of paracetamol from elongated to polyhedral-angular via particle engineering whilst maintaining the stable polymorphic form (form I: monoclinic form). The engineered paracetamol crystals obtained in the present investigation showed better technological and biopharmaceutical properties in comparison to the commercial paracetamol. Engineered paracetamol crystals were obtained using antisolvent crystallization technique in the presence of various concentrations (0.1, 0.5 and 1%, w/w) of additives, namely, polyvinyl alcohol (PVA), Avicel PH 102 (microcrystalline cellulose), Brij 58, methylcellulose (MC) and polyethylene glycol having different molecular weights (PEGs 1500, 6000 and 8000). Paracetamols crystallized in the presence of Avicel (or physically mixed with Avicel), Brij 58 and PEG 6000 demonstrated the best compactibility over a range of compaction pressures. Brij-crystallized paracetamol provided the fastest dissolution rate among all the paracetamol batches. Paracetamols crystallized in the presence of PVA or Avicel, or physically mixed with Avicel demonstrated a reduced degree of crystallinity in comparison to the other paracetamols. This study showed that the type, the grade and the concentration of additives could influence the physical stability such as flow, crystallinity and polymorphic transformation of paracetamol, the technological and biopharmaceutical properties of paracetamol. Stable polymorphic form of paracetamol with optimal tableting characteristics can be achieved through particle engineering. PMID:24480534

  3. Raman scattering in crystals

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, D.F.

    1988-09-30

    A tutorial presentation is given of Raman scattering in crystals. The physical concepts are emphasized rather than the detailed mathematical formalism. Starting with an introduction to the concepts of phonons and conservation laws, the effects of photon-phonon interactions are presented. This interaction concept is shown for a simple cubic crystal and is extended to a uniaxial crystal. The correlation table method is used for determining the number and symmetry of the Raman active modes. Finally, examples are given to illustrate the relative ease of using this group theoretical method and the predictions are compared with measured Raman spectra. 37 refs., 17 figs., 6 tabs.

  4. Magnetic ions in crystals

    CERN Document Server

    Stevens, K W

    2014-01-01

    There have been many demonstrations, particularly for magnetic impurity ions in crystals, that spin-Hamiltonians are able to account for a wide range of experimental results in terms of much smaller numbers of parameters. Yet they were originally derived from crystal field theory, which contains a logical flaw; electrons on the magnetic ions are distinguished from those on the ligands. Thus there is a challenge: to replace crystal field theory with one of equal or greater predictive power that is based on a surer footing. The theory developed in this book begins with a generic Hamiltonian, on

  5. Friction between incommensurate crystals

    OpenAIRE

    Friedel, Jacques; De Gennes, Pierre-Gilles

    2006-01-01

    Abstract We present an overview of friction processes expected between two ideal crystals of strong layers (graphite, MoS?u...) when one crystal is rotated with respect to the other by a certain angle Ye. We assume perfect conditions: no impurities; no preexisting dislocations in the bulk of the crystals; slow gliding velocities. Two regimes show up: a) weak coupling when Ye>U?u/U_{L}, where U?u (U_{L}) are typical intra (inter) layer interactions. Here we expect weak friction, con...

  6. Raman scattering in crystals

    International Nuclear Information System (INIS)

    A tutorial presentation is given of Raman scattering in crystals. The physical concepts are emphasized rather than the detailed mathematical formalism. Starting with an introduction to the concepts of phonons and conservation laws, the effects of photon-phonon interactions are presented. This interaction concept is shown for a simple cubic crystal and is extended to a uniaxial crystal. The correlation table method is used for determining the number and symmetry of the Raman active modes. Finally, examples are given to illustrate the relative ease of using this group theoretical method and the predictions are compared with measured Raman spectra. 37 refs., 17 figs., 6 tabs

  7. The Crystal Hotel: A Microfluidic Approach to Biomimetic Crystallization.

    Science.gov (United States)

    Gong, Xiuqing; Wang, Yun-Wei; Ihli, Johannes; Kim, Yi-Yeoun; Li, Shunbo; Walshaw, Richard; Chen, Li; Meldrum, Fiona C

    2015-12-01

    A "crystal hotel" microfluidic device that allows crystal growth in confined volumes to be studied in situ is used to produce large calcite single crystals with predefined crystallographic orientation, microstructure, and shape by control of the detailed physical environment, flow, and surface chemistry. This general approach can be extended to form technologically important, nanopatterned single crystals. PMID:26479157

  8. Crystal Electrostatic Energy

    CERN Document Server

    Ivanchin, Alexander

    2010-01-01

    It has been shown that to calculate the parameters of the electrostatic field of the ion crystal lattice it sufficient to take into account ions located at a distance of 1-2 lattice spacings. More distant ions make insignificant contribution. As a result, the electrostatic energy of the ion lattice in the alkaline halide crystal produced by both positive and negative ions is in good agreement with experiment when the melting temperature and the shear modulus are calculated. For fcc and bcc metals the ion lattice electrostatic energy is not sufficient to obtain the observed values of these parameters. It is possible to resolve the contradiction if one assumes that the electron density is strongly localized and has a crystal structure described by the lattice delta - function. As a result, positive charges alternate with negative ones as in the alkaline halide crystal. Such delta-like localization of the electron density is known as a model of nearly free electrons.

  9. Inclusions in DKDP crystal

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The shape and the size of inclusions in DKDP crystal have been observed and measured microscopically.Three kinds of inclusions were found and the components of the inclusions were measured. The formation mechanisms were proposed and discussed.``

  10. Intercompany comparison

    OpenAIRE

    Vančura, Jiří

    2014-01-01

    The aim of this thesis is to perform the comparison between the largest drugstores and parfumeries in the Czech Republic and evaluation of financial situation by using ratio analysis from 2009 to 2013. For comparison were chosen dm drogerie markt s.r.o., Rossmann, spol. s.r.o, Family drogerie s.r.o, Sephora s.r.o. and Yves Rocher s.r.o. Intercompany comparison was done using univariate and multivariate methods. Among multivariate methods were included method of simple sum of the sequence, met...

  11. Photonic density of states maps for design of photonic crystal devices

    OpenAIRE

    Sukhoivanov, I. A.; Guryev, I. V.; Lucio, J. A. Andrade; Mendez, E. Alvarado; Trejo-Duran, M.; Torres-Cisneros, M.

    2010-01-01

    In this work, it has been investigated whether photonic density of states maps can be applied to the design of photonic crystal-based devices. For this reason, comparison between photonic density of states maps and transmittance maps was carried out. Results of comparison show full correspondence between these characteristics. Photonic density of states maps appear to be preferable for the design of photonic crystal devices, than photonic band gap maps presented earlier and than transmittance...

  12. Characterizing protein crystal nucleation

    Science.gov (United States)

    Akella, Sathish V.

    We developed an experimental microfluidic based technique to measure the nucleation rates and successfully applied the technique to measure nucleation rates of lysozyme crystals. The technique involves counting the number of samples which do not have crystals as a function of time. Under the assumption that nucleation is a Poisson process, the fraction of samples with no crystals decays exponentially with the decay constant proportional to nucleation rate and volume of the sample. Since nucleation is a random and rare event, one needs to perform measurements on large number of samples to obtain good statistics. Microfluidics offers the solution of producing large number of samples at minimal material consumption. Hence, we developed a microfluidic method and measured nucleation rates of lysozyme crystals in supersaturated protein drops, each with volume of ˜ 1 nL. Classical Nucleation Theory (CNT) describes the kinetics of nucleation and predicts the functional form of nucleation rate in terms of the thermodynamic quantities involved, such as supersaturation, temperature, etc. We analyzed the measured nucleation rates in the context of CNT and obtained the activation energy and the kinetic pre-factor characterizing the nucleation process. One conclusion is that heterogeneous nucleation dominates crystallization. We report preliminary studies on selective enhancement of nucleation in one of the crystal polymorprhs of lysozyme (spherulite) using amorphous mesoporous bioactive gel-glass te{naomi06, naomi08}, CaO.P 2O5.SiO2 (known as bio-glass) with 2-10 nm pore-size diameter distribution. The pores act as heterogeneous nucleation centers and claimed to enhance the nucleation rates by molecular confinement. The measured kinetic profiles of crystal fraction of spherulites indicate that the crystallization of spherulites may be proceeding via secondary nucleation pathways.

  13. Luminescence of laminated crystals

    International Nuclear Information System (INIS)

    The photoluminescence and reflection spectra of single crystals PbI2, SnI2, CdI2 and their solid mixed solutions were investigated. It has been established that the n-1 of the exciton spectrum of luminescence of PrI2 crystals is a doublet, whose origin is associated with a longitudinal-transverse splitting of excitons due to the effects of strong light-exciton mixing

  14. Polymer semiconductor crystals

    OpenAIRE

    Jung Ah Lim; Feng Liu; Sunzida Ferdous; Murugappan Muthukumar; Briseno, Alejandro L.

    2010-01-01

    One of the long-standing challenges in the field of polymer semiconductors is to figure out how long interpenetrating and entangled polymer chains self-assemble into single crystals from the solution phase or melt. The ability to produce these crystalline solids has fascinated scientists from a broad range of backgrounds including physicists, chemists, and engineers. Scientists are still on the hunt for determining the mechanism of crystallization in these information-rich materials. Understa...

  15. Fractal Photonic Crystal Waveguides

    OpenAIRE

    Monsoriu, Juan A.; Zapata-Rodriguez, Carlos J.; Silvestre, Enrique; Furlan, Walter D.

    2004-01-01

    We propose a new class of one-dimensional (1D) photonic waveguides: the fractal photonic crystal waveguides (FPCWs). These structures are photonic crystal waveguides (PCWs) etched with fratal distribution of grooves such as Cantor bars. The transmission properties of the FPCWs are investigated and compared with those of the conventional 1D PCWs. It is shown that the FPCW transmission spectrum has self-similarity properties associated with the fractal distribution of grooves. Furthermore, FPCW...

  16. Macromolecular Crystal Quality

    Science.gov (United States)

    Snell, Edward H.; Borgstahl, Gloria E. O.; Bellamy, Henry D.; Curreri, Peter A. (Technical Monitor)

    2001-01-01

    There are many ways of judging a good crystal. Which we use depends on the qualities we seek. For gemstones size, clarity and impurity levels (color) are paramount. For the semiconductor industry purity is probably the most important quality. For the structural crystallographer the primary desideratum is the somewhat more subtle concept of internal order. In this chapter we discuss the effect of internal order (or the lack of it) on the crystal's diffraction properties.

  17. Living liquid crystals

    OpenAIRE

    Zhou, Shuang; Sokolov, Andrey; Lavrentovich, Oleg D.; Aranson, Igor S.

    2014-01-01

    Collective motion of self-propelled organisms or synthetic particles often termed active fluid has attracted enormous attention in broad scientific community because of it fundamentally non-equilibrium nature. Energy input and interactions among the moving units and the medium lead to complex dynamics. Here we introduce a new class of active matter, living liquid crystals (LLCs) that combine living swimming bacteria with a lyotropic liquid crystal. The physical properties of LLCs can be contr...

  18. Planar photonic crystal

    OpenAIRE

    Nedeljkovic, Dusan; Pearsall, T. P.; Kuchinsky, S. A.; Mikhailov, M. D.; Lončar, Marko; Scherer, Axel

    2001-01-01

    We present results of guiding light in a single-line-defect planar photonic crystal (PPC) waveguide with 90° and 60° bends. The wave guiding is obtained by total internal reflection perpendicular to the plane of propagation and by the photonic band gap for the 2D photonic crystal in the plane. The results for photonic waveguiding are shown and demonstrated at 1.5 µm wavelength.

  19. Building a crystal palace

    CERN Multimedia

    2007-01-01

    The end-caps of the CMS electromagnetic calorimeter (ECAL) take shape as the first quadrant was completed on Wednesday 3 October. 1831 crystals, organised into five by five blocks named ‘supercrystals’, make up the first quadrant of Dee 1.With the 61,200-crystal barrel of its electromagnetic calorimeter (ECAL) complete, CMS is now building the endcaps, on the tenth anniversary of their initial design. Crystals for the endcaps were the last to be made, so the race is now on to have them all in place and ready for the turn-on of the LHC next year. Assembly of the first of eight quadrants began in June and crystal mounting was completed on Wednesday 3 October. Each crystal is transparent, has a volume just larger than a CERN coffee cup yet weighs a huge 1.5kg. 1831 of these lead tungstate crystals went into the first quadrant from a total 14,648 in the endcaps. The lead and tungsten account for 86% of each crystal’s weight, but as project leader Dave Cockerill expl...

  20. Engineering of recombinant crystallization chaperones

    OpenAIRE

    Koide, Shohei

    2009-01-01

    The preparation of diffraction quality crystals remains the major bottleneck in macromolecular x-ray crystallography. A crystallization chaperone is an auxiliary protein, such as fragments of monoclonal antibodies, that binds to and increases the crystallization probability of a target molecule of interest. Such chaperones reduce conformational heterogeneity, mask counterproductive surfaces while extending surfaces predisposed to forming crystal contacts, and provide phasing information. Crys...

  1. The crystallization of monosodium urate.

    Science.gov (United States)

    Martillo, Miguel A; Nazzal, Lama; Crittenden, Daria B

    2014-02-01

    Gout is a common crystal-induced arthritis, in which monosodium urate (MSU) crystals precipitate within joints and soft tissues and elicit an inflammatory response. The causes of elevated serum urate and the inflammatory pathways activated by MSU crystals have been well studied, but less is known about the processes leading to crystal formation and growth. Uric acid, the final product of purine metabolism, is a weak acid that circulates as the deprotonated urate anion under physiologic conditions, and combines with sodium ions to form MSU. MSU crystals are known to have a triclinic structure, in which stacked sheets of purine rings form the needle-shaped crystals that are observed microscopically. Exposed, charged crystal surfaces are thought to allow for interaction with phospholipid membranes and serum factors, playing a role in the crystal-mediated inflammatory response. While hyperuricemia is a clear risk factor for gout, local factors have been hypothesized to play a role in crystal formation, such as temperature, pH, mechanical stress, cartilage components, and other synovial and serum factors. Interestingly, several studies suggest that MSU crystals may drive the generation of crystal-specific antibodies that facilitate future MSU crystallization. Here, we review MSU crystal biology, including a discussion of crystal structure, effector function, and factors thought to play a role in crystal formation. We also briefly compare MSU biology to that of uric acid stones causing nephrolithasis, and consider the potential treatment implications of MSU crystal biology. PMID:24357445

  2. Growth of KH2PO4 crystals at constant temperature and supersaturation. Final report, 20 October 1980-20 October 1981

    International Nuclear Information System (INIS)

    A large three-zone cyrstallizer system was constructed and successfully operated for growing KH2PO4 single crystals. Under conditions of constant crystallization temperature and supersaturation, growth rates exceeding 5 mm per day were demonstrated for KH2PO4 crystals of 5 x 5 cm cross section. The optical quality of these crystals was equivalent to that of crystals grown at rates presently considered as state-of-the-art (approx. 1 mm/day). Sample crystals were supplied for comparison testing. The three-zone system appears to be ideally suitable for growth of large-diameter KH2PO4 crystals for the Laser Fusion Program

  3. Photonic Crystal Sensors Based on Porous Silicon

    Directory of Open Access Journals (Sweden)

    Claudia Pacholski

    2013-04-01

    Full Text Available Porous silicon has been established as an excellent sensing platform for the optical detection of hazardous chemicals and biomolecular interactions such as DNA hybridization, antigen/antibody binding, and enzymatic reactions. Its porous nature provides a high surface area within a small volume, which can be easily controlled by changing the pore sizes. As the porosity and consequently the refractive index of an etched porous silicon layer depends on the electrochemial etching conditions photonic crystals composed of multilayered porous silicon films with well-resolved and narrow optical reflectivity features can easily be obtained. The prominent optical response of the photonic crystal decreases the detection limit and therefore increases the sensitivity of porous silicon sensors in comparison to sensors utilizing Fabry-Pérot based optical transduction. Development of porous silicon photonic crystal sensors which allow for the detection of analytes by the naked eye using a simple color change or the fabrication of stacked porous silicon photonic crystals showing two distinct optical features which can be utilized for the discrimination of analytes emphasize its high application potential.

  4. The Fresnel coefficients of a two-dimensional atomic crystal

    CERN Document Server

    Merano, Michele

    2016-01-01

    I deduce the Fresnel coefficients valid for a generic two dimensional crystal. In general the optical properties of an atomically thin monolayer are interpreted by modelling it as a homogeneous medium with an effective thickness. The comparison with experimental results, published in literature, shows that the Fresnel coefficients are better suited to this end than the above mentioned model.

  5. Design of Agglomerated Crystals of Ibuprofen During Crystallization: Influence of Surfactant

    Directory of Open Access Journals (Sweden)

    Maryam Maghsoodi

    2011-01-01

    Full Text Available Objective(sIbuprofen is a problematic drug in tableting, and dissolution due to its poor solubility, hydrophobicity, and tendency to stick to surface. Because of the bad compaction behavior ibuprofen has to be granulated usually before tableting. However, it would be more satisfactory to obtain directly during the crystallization step crystalline particles that can be directly compressed and quickly dissolved. Materials and Methods Crystallization of ibuprofen was carried out using the quasi emulsion solvent diffusion method in presence of surfactant (sodium lauryl sulfate (SLS, Tween 80. The particles were characterized by differential scanning calorimetry (DSC, powder X-ray diffraction (XRPD and were evaluated for particle size, flowability, drug release and tableting behavior. ResultsIbuprofen particles obtained in the presence of surfactants consisted of numerous plate- shaped crystals which had agglomerated together as near spherical shape. The obtained agglomerates exhibited significantly improved micromeritic properties as well as tableting behavior than untreated drug crystals. The agglomerates size and size distribution was largely controlled by surfactant concentration, but there was no significant influence found on the tableting properties. The dissolution tests showed that the agglomerates obtained in presence of SLS exhibited enhanced dissolution rate while the agglomerates made in the presence of Tween 80 had no significant impact on dissolution rate of ibuprofen in comparison to untreated sample. The XRPD and DSC results showed that during the agglomeration process, ibuprofen did not undergo any polymorphic changes.Conclusion The study highlights the influence of surfactants on crystallization process leading to modified performance.

  6. Crystal Growth Models of Dexamethasone Sodium Phosphate in a MSMPR Reactive Crystallizer

    Institute of Scientific and Technical Information of China (English)

    郝红勋; 王静康; 王永莉; 侯宝红

    2005-01-01

    The reactive crystallization process of dexamethasone sodium phosphate was investigated in a continuous mixed-suspension, mixed-product-removal(MSMPR) crystallizer. Analyzing experimental data, it was found that the growth of product crystal was size-dependent. The Bransom, CR, ASL, M J2 and M J3 size-dependent growth models were discussed in details. Using experimental steady state population density data of dexamethasone sodium phosphate, parameters of five size-dependent growth models were determined by the method of non-linear least-squares. By comparison of experimental population density and linear growth rate data with those obtained from the five size-dependent growth models, it was found that the MJ3 model predicts the growth more accurately than do the other four models. Based on the theory of population balance, the crystal nucleation and growth rate equations of dexamethasone sodium phosphate were determined by non-linear regression method. The effects of different operation parameters such as supersaturation, magma density and temperature on the quality of product crystal were also discussed, and the optimal operation conditions were derived.

  7. [In vitro effect of Hordeum vulgare on the crystallization of calcium oxalate monohydrate (whewellite)].

    Science.gov (United States)

    Djaroud, Samira; Harrache, Djamila; Amar, Amina

    2012-01-01

    The recommended conservative treatment of hyperoxaluria is mainly based on hyperhydration and ingestion of inhibitors of crystallization. In accordance with this context, the aim of this study was to determine the in vitro effect of Hordeum vulgare on calcium oxalate crystallization oxalo-dependent. The crystallization of calcium oxalate monohydrate in supersaturated aqueous solution at 37 °C, was followed in a model turbidimetric continuous in a closed system. The proposed model is very good reproducibility (CV < 10%), crystallization was monitored continuously in the presence of Hordeum vulgare at different concentrations (0.0625 to 1 g/L). The comparison of turbidimetric parameters, that characterize the growth stage of monohydrated oxalate calcium crystals and observation of the crystals obtained at the end of crystallization into scanning electron microscopy, have been able to demonstrate the inducing effect of Hordeum vulgare to 0.0625 g/L and a slight inhibitory effect at the others concentrations. PMID:23207820

  8. 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

  9. Characteristics of a stilbene scintillation crystal in a neutron spectrometer

    International Nuclear Information System (INIS)

    Various organic scintillators are commonly used as the detecting material for neutrons, but these detectors are less sensitive to gamma rays. In particular, stilbene crystals and BC501A (NE213, EJ301) have good pulse-shape discrimination (PSD) between neutron and gamma-ray events, and have been selected as the media for fast-neutron detection among the organic, inorganic and plastic materials in a mixed radiation field. Although some of the scintillation characteristics of stilbene crystals have been studied, the detailed scintillation characteristics of the crystal are not completely understood. In this study, the light yield, decay time and pulse shape discrimination capability of a stilbene crystal were measured because this crystal is an optimized detector in a large flux of neutrons such as those might be found in cyclotron and charged particle accelerator facilities. The pulse-shape discrimination of neutrons and gamma rays with a stilbene crystal was measured using a 252Cf neutron source at room temperature. A neutron tagger module was used for the neutron and gamma separation using the charge comparison method in real time. The total pulse width for the charge integration and the delay from the peak-to tail start time were optimized for a better neutron and gamma separation. The relative light yield and decay time of the stilbene crystal scintillator were also measured. - Highlights: ► Decay time of Stilbene crystal was measured using pulse shape discrimination method. ► The characteristic of Stilbene crystal is compared with that of BC501A scintillator. ► Energy resolution of Stilbene crystal was estimated using MCNPX simulation

  10. Instabilities in liquid crystals

    International Nuclear Information System (INIS)

    This thesis contains theoretical work dealing with the effects of magnetic and electric fields on samples of nematic, smectic A and smectic C liquid crystals. Some background material along with the continuum theory is introduced in Chapter 2. In Chapter 3 we consider the effect on the director within an infinite sample of nematic liquid crystal which is subjected to crossed electric and magnetic fields. In particular we examine the stability of the travelling waves which describe the director motion by considering the behaviour of the stable perturbations as time increases. The work of Chapter 4 examines a bounded sample of smectic A liquid crystal in two dimensions which is subjected to a magnetic field. It can be shown that layer undulations may occur after a critical threshold is reached. The effects of various forms of pressure are also studied and in the case when pressure is included it is shown that layer undulations will always occur regardless of the field strength. Chapter 5 extends the work of Chapter 4 to three dimensions. We consider the effect of adding a dynamical term and study the stability of these solutions. Also we examine how the layers undulate when the sample of smectic A liquid crystal is confined to various cylindrical geometries and subjected to a magnetic field and a uniform pressure. In Chapter 6 we consider a sample of smectic C liquid crystal which is subjected to an oscillatory electric field. The motion of the c-director is complicated and we examine the differences which occur for differing dielectric anisotropies. Finally, in Chapter 7 we study how a sample of smectic C liquid crystal behaves when it is subjected to a uniform shear flow within the smectic plane. We find travelling wave solutions for the behaviour of the c-director and adapt these solutions to incorporate the effects of an applied field. (author)

  11. Growth and properties of InP single crystals

    Science.gov (United States)

    Dun-fu, Fang; Xiang-xi, Wang; Yong-quan, Xu; Li-tong, Tan

    1984-04-01

    InP single crystals with various dopants including S, Sn, Zn and Fe have been grown successfully by the Czochralski method under high pressure with liquid encapsulation. It is found that by carefully adjusting the thermal symmetry of the heating field and by further improving the quality of the polycrystals and by dehydrating B 2O 3, twin-free InP crystals can be obtained even with a shoulder angle of up to 54°, and defects caused by thermal decomposition appear on the surface of the crystals during pulling. Furthermore, a comparison of the crystal perfection and uniformity between S-doped and Sn-doped InP crystals shows that the quality of the former is better than that of the latter. Dislocation-free Zn-doped p-InP single crystals without precipitates have also been easily obtained when the carrier concentration is greater than 2×10 18 cm -3 and the diameter less than 30 mm. By controlling the iron content, semi-insulating thermally stable single crystals of InP doped with ⩽0.03 wt% of Fe without precipitates and with a homogeneous resistivity can be produced.

  12. Analysis of crystallization risk in double effect absorption refrigeration systems

    International Nuclear Information System (INIS)

    Absorption refrigeration systems are an alternative to vapor compression ones in cooling and refrigeration applications. In comparison with single effect absorption units, double effect systems have improved performance. Also, they are more available commercially than the other multi effect absorption cycles. An important challenge in the operation of such systems is the possibility of crystallization within them. This is especially true in developing air-cooled absorption systems, which are attractive because cooling tower and associated installation and maintenance issues can be avoided. Therefore, distinguishing the working conditions that may cause crystallization can be useful in the design and control of these systems. In this paper a computational model has been developed to study and compare the effects of operating parameters on crystallization phenomena in three classes of double effect lithium bromide-water absorption refrigeration systems (series, parallel and reverse parallel) with identical refrigeration capacities. It is shown that the range of operating conditions without crystallization risks in the parallel and the reverse parallel configurations is wider than those of the series flow system. - Highlights: → We study crystallization of double effect absorption refrigeration systems. → We consider series, parallel and reverse parallel cycles. → We study the effect of operating conditions on crystallization. → We choose optimum distribution ratio for parallel and reverse parallel systems. → Crystallization possibility is low in parallel and reverse parallel cycles.

  13. Crystal Structures of Furazanes

    Directory of Open Access Journals (Sweden)

    Thomas M. Klapötke

    2015-09-01

    Full Text Available Several nitrogen-rich salts of 3-nitramino-4-nitrofurazane and dinitraminoazoxyfurazane were synthesized and characterized by various spectroscopic methods. The crystal structures were determined by low temperature single crystal X-ray diffraction. Moreover the sensitivities toward thermal and mechanical stimuli were determined by differential thermal analysis (DTA and BAM (Bundesanstalt für Materialforschung und -prüfung methods. The standard enthalpies of formation were calculated for all compounds at the CBS-4M level of theory, and the energetic performance was predicted with the EXPLO5 V6.02 computer code.

  14. FRACTIONAL CRYSTALLIZATION FEED ENVELOPE

    International Nuclear Information System (INIS)

    Laboratory work was completed on a set of evaporation tests designed to establish a feed envelope for the fractional crystallization process. The feed envelope defines chemical concentration limits within which the process can be operated successfully. All 38 runs in the half-factorial design matrix were completed successfully, based on the qualitative definition of success. There is no feed composition likely to be derived from saltcake dissolution that would cause the fractional crystallization process to not meet acceptable performance requirements. However, some compositions clearly would provide more successful operation than other compositions

  15. Functionalizing Designer DNA Crystals

    Science.gov (United States)

    Chandrasekaran, Arun Richard

    Three-dimensional crystals have been self-assembled from a DNA tensegrity triangle via sticky end interaction. The tensegrity triangle is a rigid DNA motif containing three double helical edges connected pair-wise by three four-arm junctions. The symmetric triangle contains 3 unique strands combined in a 3:3:1 ratio: 3 crossover, 3 helical and 1 central. The length of the sticky end reported previously was two nucleotides (nt) (GA:TC) and the motif with 2-helical turns of DNA per edge diffracted to 4.9 A at beam line NSLS-X25 and to 4 A at beam line ID19 at APS. The purpose of these self-assembled DNA crystals is that they can be used as a framework for hosting external guests for use in crystallographic structure solving or the periodic positioning of molecules for nanoelectronics. This thesis describes strategies to improve the resolution and to incorporate guests into the 3D lattice. The first chapter describes the effect of varying sticky end lengths and the influence of 5'-phosphate addition on crystal formation and resolution. X-ray diffraction data from beam line NSLS-X25 revealed that the crystal resolution for 1-nt (G:C) sticky end was 3.4 A. Motifs with every possible combination of 1-nt and 2-nt sticky-ended phosphorylated strands were crystallized and X-ray data were collected. The position of the 5'-phosphate on either the crossover (strand 1), helical (strand 2), or central strand (3) had an impact on the resolution of the self-assembled crystals with the 1-nt 1P-2-3 system diffracting to 2.62 A at APS and 3.1 A at NSLS-X25. The second chapter describes the sequence-specific recognition of DNA motifs with triplex-forming oligonucleotides (TFOs). This study examined the feasibility of using TFOs to bind to specific locations within a 3-turn DNA tensegrity triangle motif. The TFO 5'-TTCTTTCTTCTCT was used to target the tensegrity motif containing an appropriately embedded oligopurine.oligopyrimidine binding site. As triplex formation involving cytidine

  16. Crystal growth, crystal field evaluation and spectroscopy for thulium in monoclinic KGd(WO{sub 4}){sub 2} and KLu(WO{sub 4}){sub 2} laser crystals

    Energy Technology Data Exchange (ETDEWEB)

    Pujol, M C; Aguilo, M; Diaz, F [Fisica i Cristallografia de Materials (FiCMA), Universitat Rovira i Virgili (URV), Campus Sescelades c/ Marcel.lIDomingo, s/n, E-43007 Tarragona (Spain); Cascales, C [Instituto de Ciencia de Materiales de Madrid ICMM, Consejo Superior de Investigaciones CientIficas CSIC, E-28049 Cantoblanco, Madrid (Spain)], E-mail: ccascales@icmm.csic.es

    2008-08-27

    A comparison of the suitability of two Tm{sup 3+}-doped monoclinic double tungstate KRE(WO{sub 4}){sub 2} (RE = Gd{sup 3+} or Lu{sup 3+}) laser crystals was carried out based on crystal growth conditions and the strength of crystal field interactions provided by the corresponding host at the Tm{sup 3+} site. For the same 3% Tm{sup 3+} substitution level, macrodefect-free single crystals can be grown, with higher cooling rates and lower temperatures for the KLu(WO{sub 4}){sub 2} host. Furthermore, the information provided by the phenomenological crystal field analysis of low temperature polarized spectroscopic data for both hosts indicates that KLu(WO{sub 4}){sub 2} exhibits the stronger crystal field and thus an enhanced {sup 3}H{sub 6} splitting compared to KGd(WO{sub 4}){sub 2}. Considering these factors as well as its calculated higher emission cross sections, it is concluded that KLu(WO{sub 4}){sub 2} is the most suitable of the two hosts for Tm{sup 3+} doping.

  17. A Comparison between TGT and Cz Grown Nd:YAG

    Institute of Scientific and Technical Information of China (English)

    Benxue JIANG; Jun XU; Hong jun LI; Jingya WANG; Guangjun ZHAO

    2006-01-01

    Large sized neodymium-doped Y3Al5O12(Nd:YAG)laser crystals have been grown by temperature gradient technique(TGT)method and compared with Czochralski(Cz)method. The comparison of these two crystal growth methods has been listed. The results showed that the TGT method has many advantages over the Cz method. The concentration distribution of Nd ions in the crystals was determined and the absorption spectra of these crystals have been investigated and compared. The TGT grown highly doped Nd:YAG crystal has a larger absorption FWHM than that of Cz grown Nd:YAG crysral. Highly doped Nd:YAG(~2.8 at. pct)crystals could be obtained by TGT.

  18. Chemistry of microporous crystals

    International Nuclear Information System (INIS)

    This volume contains three papers which are in INIS scope, entitled respectively: 129Xe-NMR study of the crystallization of SAPO-37, NMR studies of cation localization in zeolites, developments in x-ray and neutron diffraction methods for zeolites. (H.W.). refs.; figs.; tabs

  19. Laser schlieren crystal monitor

    Science.gov (United States)

    Owen, Robert B. (Inventor); Johnston, Mary H. (Inventor)

    1987-01-01

    A system and method for monitoring the state of a crystal which is suspended in a solution is described which includes providing a light source for emitting a beam of light along an optical axis. A collimating lens is arranged along the optical axis for collimating the emitted beam to provide a first collimated light beam consisting of parallel light rays. By passing the first collimated light beam through a transparent container, a number of the parallel light rays are deflected off the surfaces of said crystal being monitored according to the refractive index gradient to provide a deflected beam of deflected light rays. A focusing lens is arranged along optical axis for focusing the deflected rays towards a desired focal point. A knife edge is arranged in a predetermined orientation at the focal point; and a screen is provided. A portion of the deflected beam is blocked with the knife edge to project only a portion of the deflected beam. A band is created at one edge of the image of the crystal which indicates the state of change of the surface of the crystal being monitored.

  20. Thermoelectricity in liquid crystals

    Science.gov (United States)

    Mohd Said, Suhana; Nordin, Abdul Rahman; Abdullah, Norbani; Balamurugan, S.

    2015-09-01

    The thermoelectric effect, also known as the Seebeck effect, describes the conversion of a temperature gradient into electricity. A Figure of Merit (ZT) is used to describe the thermoelectric ability of a material. It is directly dependent on its Seebeck coefficient and electrical conductivity, and inversely dependent on its thermal conductivity. There is usually a compromise between these parameters, which limit the performance of thermoelectric materials. The current achievement for ZT~2.2 falls short of the expected threshold of ZT=3 to allow its viability in commercial applications. In recent times, advances in organic thermoelectrics been significant, improving by over 3 orders of magnitude over a period of about 10 years. Liquid crystals are newly investigated as candidate thermoelectric materials, given their low thermal conductivity, inherent ordering, and in some cases, reasonable electrical conductivity. In this work the thermoelectric behaviour of a discotic liquid crystal, is discussed. The DLC was filled into cells coated with a charge injector, and an alignment of the columnar axis perpendicular to the substrate was allowed to form. This thermoelectric behavior can be correlated to the order-disorder transition. A reasonable thermoelectric power in the liquid crystal temperature regime was noted. In summary, thermoelectric liquid crystals may have the potential to be utilised in flexible devices, as a standalone power source.

  1. Nonlinear Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Hansen, Kim Per

    2004-01-01

    applications based on four-wave mixing. In addition, the broad supercontinua have a range of applications within biomedicine, telecommunication and metrology. The special structure of photonic crystal fibers opens up the possibility, in a simple way, to create polarization-maintaining fibers without the use of...

  2. Photonic Crystal Fibers

    Institute of Scientific and Technical Information of China (English)

    William J. Wadsworth; Jonathan C. Knight; William H. Reeves; Philip St.J. Russell

    2003-01-01

    By offering greatly enhanced control of light compared to conventional step-index structures, photonic crystal fibres are radically improving the performance of linear and nonlinear fibre devices, including gas-Raman cells, super-continuum generators, soliton systems and cladding-pumped lasers.

  3. Photonic Crystal VCSELs

    Institute of Scientific and Technical Information of China (English)

    D.; S.; Song; J.; W.; Paek; K.; H.; Lee; Y.; H.; Lee

    2003-01-01

    Photonic crystal vertical cavity surface emitting lasers (PC VCSELs) are reviewed. The PC VCSEL shows single-transverse-mode continuous wave operation in the entire current range with side mode suppression ratio 35-40 dB. A simple 3-D plane wave expansion method is found to be very effective in analyzing the modal properties of the PC VCSELs.

  4. Photonic Crystal VCSELs

    Institute of Scientific and Technical Information of China (English)

    D. S. Song; J. W. Paek; K. H. Lee; Y. H. Lee

    2003-01-01

    Photonic crystal vertical cavity surface emitting lasers (PC VCSELs) are reviewed. The PC VCSEL shows single-transverse-mode continuous wave operation in the entire current range with side mode suppression ratio 35-40dB. A simple 3-D plane wave expansion method is found to be very effective in analyzing the modal properties of the PC VCSELs.

  5. Liquid crystal display

    International Nuclear Information System (INIS)

    An improved liquid crystal display device is described which can display letters, numerals and other necessary patterns in the night time using a minimized amount of radioactive material. To achieve this a self-luminous light source is placed in a limited region corresponding to a specific display area. (U.K.)

  6. Incommensurability in crystal structures

    International Nuclear Information System (INIS)

    Incommensurate or modulated crystal structures (TaS2, Srsub(1-p)Cr2Sesub(4-p), etc.) are examined and compared with superstructures (TaSe2, Basub(1-p)Cr2Sesub(4-p)). Observed and calculated structure factors are given for Eusub(1-p)Cr2Sesub(4-p). (C.F.)

  7. Photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Sanchez Bjarklev, Araceli

    bandgap structures and thoughts of inspiration from microstructures in nature, as well as classification of the various photonic crystal fibres, theoretical tools for analysing the fibres and methods of their production. Finally, the book points toward some of the many future applications, where photonic...

  8. The Crystal Set

    Science.gov (United States)

    Greenslade, Thomas B., Jr.

    2014-01-01

    In past issues of this journal, the late H. R. Crane wrote a long series of articles under the running title of "How Things Work." In them, Dick dealt with many questions that physics teachers asked themselves, but did not have the time to answer. This article is my attempt to work through the physics of the crystal set, which I thought…

  9. Crystal clustering and non-Newtonian rheology of low-viscosity crystal-poor magmas

    Science.gov (United States)

    Campagnola, Silvia; Vona, Alessandro; Romano, Claudia; Giordano, Guido

    2016-04-01

    We have investigated the rheology of liquid and crystal-bearing tephriphonolite magmas from the Colli Albani volcanic district. High (1124 - 1569 ° C) and low (690 - 800 ° C) temperature anhydrous liquid viscosities were determined by a combination of concentric cylinder (101.0 to 103.6 Pa s) and micropenetration (109.2 to 1012.1 Pa s) viscometry. Comparison with literature data reveals that at high temperatures, viscosity seems to be related to the melts degree of polymerization (NBO/T), while at low temperatures the dependency is not linear with values of viscosity higher than expected. Subliquidus isothermal crystallization experiments and viscosity determinations were carried out at high temperature (1150 - 1240 ° C) in air using a concentric cylinder apparatus at constant shear strain rate (γ' = 0.1 s‑1). The overall crystal fraction varies between φ = 0.06 at 1240 ° C (leucite) and φ = 0.34 at 1150 ° C (leucite φ = 0.32 + plagioclase φ = 0.02), with a direct linear increase of crystal content with decreasing temperature which parallels the viscosity increase. The inspection of products quenched at the end of the crystallization stage, defined when viscosity reaches a constant value, reveals strong evidence of leucite clustering. After the first segment of the experiment, performed at a constant shear rate, a second stage of experiments at variable shear rate was performed, comprised of an up-ramp (γ' = 0.1 - 0.9 s‑1) and a down-ramp (γ'= 0.9 - 0.1 s‑1) segment. At the end of the down-ramp, leucite crystals appear sub-spherical and unclustered. For the same applied shear rate, the viscosity values of the up-ramp are not recovered within the experimental time-scale, indicating strain and strain-rate dependent rheology for these suspensions. While the down-ramp viscosity data are shown to be in perfect agreement with literature models, discrepancies between the up-ramp data and pre-existing predicting models have been observed. We suggest that

  10. High-resolution X-ray study of the effects of deuteration on crystal growth and the crystal structure of proteinase K

    International Nuclear Information System (INIS)

    A high-resolution X-ray crystallographic study of the effects of solvent deuteration on the crystallization of proteinase K shows negligibly small degradations of the crystals owing to solvent deuteration and small structural differences between nondeuterated and deuterated crystals of proteinase K. Deuteration of macromolecules is an important technique in neutron protein crystallography. Solvent deuteration of protein crystals is carried out by replacing water (H2O) with heavy water (D2O) prior to neutron diffraction experiments in order to diminish background noise. The effects of solvent deuteration on the crystallization of proteinase K (PK) with polyethylene glycol as a precipitant were investigated using high-resolution X-ray crystallography. In previous studies, eight NO3− anions were included in the PK crystal unit cell grown in NaNO3 solution. In this study, however, the PK crystal structure did not contain NO3− anions; consequently, distortions of amino acids arising from the presence of NO3− anions were avoided in the present crystal structures. High-resolution (1.1 Å) X-ray diffraction studies showed that the degradation of PK crystals induced by solvent deuteration was so small that this degradation would be negligible for the purpose of neutron protein crystallography experiments at medium resolution. Comparison of the nonhydrogen structures of nondeuterated and deuterated crystal structures demonstrated very small structural differences. Moreover, a positive correlation between the root-mean-squared differences and B factors indicated that no systematic difference existed

  11. Protein Crystals of Raf Kinase

    Science.gov (United States)

    1995-01-01

    This image shows crystals of the protein raf kinase grown on Earth (photo a) and on USML-2 (photo b). The space-grown crystals are an order of magnitude larger. Principal Investigator: Dan Carter of New Century Pharmaceuticals

  12. FTIR spectroscopy of borate crystals

    Science.gov (United States)

    Kovacs, Laszlo; Beregi, E.; Polgar, K.; Peter, A.

    1999-03-01

    Infrared absorption spectroscopy has been used to study the vibrational modes in various borate crystals, the electronic transitions of Nd3+ ions in NYAB, and the stretching vibration of hydroxyl ions in CLBO crystals.

  13. Results of the TTF-TCNQ and the calcium carbonate crystallization on the Long Duration Exposure Facility

    Science.gov (United States)

    Nielsen, Kjeld Flemming; Lind, M. David

    1992-01-01

    Experiment A0139A on the Long Duration Exposure Facility (LDEF) carried four large containers into orbit five years with crystal growth solutions for lead sulfide, calcium carbonate, and TTF-TCNQ. Although temperature data was lost, the experimental program had been working since the valves in all containers had been opened. All four experiments produced crystals of varying quality. The calcium carbonate crystals had the best appearance. The TTF-TCNQ crystals were packed together near the valve openings of the container. When taken apart, the single crystals showed some unusual morphological properties. X ray investigations as well as conductivity measurements on long duration space grown TTF-TCNQ crystals will be presented. Comparisons will be made with our previous space solution growth experiments. The TTF-TCNQ crystals are no longer of the highest interest, so this activity has been terminated in favor of calcium carbonate and calcium phosphate crystallizations.

  14. A comparative study of pure and potassium doped cadmium mercury thiocyanate single crystals grown in silica gel

    Energy Technology Data Exchange (ETDEWEB)

    Kumari, P.N.S. [Department of Physics, Auxilium College, Vellore (India); Margaret, M.B. [Department of Physics, Arignar Anna Govt. College for Women, Walajapet (India); Kalainathan, S. [School of Science and Humanities, VIT University, Vellore (India)

    2009-02-15

    Pure and potassium doped cadmium mercury thiocyanate single crystals have been obtained from silica gel by the process of diffusion. The X-ray diffraction studies reveal the crystal lattice of both pure and doped crystals to be tetragonal. The crystalline perfection of the grown crystals were investigated by high resolution X-ray diffraction analysis and the quality of the crystals are found to be extremely good. Transmission and Fourier transform infrared spectra were recorded for the grown crystals. The TG/DTA analyses show that the crystals are highly thermally stable. The mechanical strength of the crystals were studied by Vickers microhardness test and a study of their second harmonic generation efficiency in comparison with urea has been made by performing Kurtz powder test. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Electrical properties of molecular crystals

    International Nuclear Information System (INIS)

    This literature survey summarizes the electrical properties of molecular crystals: molecular crystal structure, transport and excitation mechanisms of charge-carriers, and differences compared to inorganic semi-conductors. The main results concerning the electrical conductivity of the most-studied molecular crystals are presented, together with the optical and photo-electrical properties of these crystals. Finally the different types of electrical measurements used are reviewed, as well as the limits of each method. (author)

  16. Ultrafast photonic crystal optical switching

    Institute of Scientific and Technical Information of China (English)

    GONG Qi-huang; HU Xiao-yong

    2006-01-01

    Photonic crystal,a novel and artificial photonic material with periodic dielectric distribution,possesses photonic bandgap and can control the propagation states of photons.Photonic crystal has been considered to be a promising candidate for the future integrated photonic devices.The properties and the fabrication method of photonic crystal are expounded.The progresses of the study of ultrafast photonic crystal optical switching are discussed in detail.

  17. The Crystallization of Monosodium Urate

    OpenAIRE

    Martillo, Miguel A.; Nazzal, Lama; Crittenden, Daria B.

    2014-01-01

    Gout is a common crystal-induced arthritis, in which monosodium urate (MSU) crystals precipitate within joints and soft tissues and elicit an inflammatory response. The causes of elevated serum urate and the inflammatory pathways activated by MSU crystals have been well studied, but less is known about the processes leading to crystal formation and growth. Uric acid, the final product of purine metabolism, is a weak acid that circulates as the deprotonated urate anion under physiologic condit...

  18. Thermally and optically stimulated processes in additively colored beryllium oxide crystals

    International Nuclear Information System (INIS)

    Thermally and optically stimulated processes in additively colored beryllium oxide (BeO) single crystals have been investigated. Thermally (TL) and optically stimulated luminescence (OSL) curves were measured. The comparison of TL and OSL properties of the initial and anion-defective BeO monocrystals was made. Additive coloration changes the properties of BeO monocrystals fundamentally. After additive coloration of initial BeO crystal the shape of its glow curves were simplified. The glow curve shape of anion-defective BeO crystals consist practically of monopeak with a satellite peak on its low-temperature branch, in contrast to the glow curve shape of initial crystals, which consist of several peaks. The above mentioned feature of the additively colored BeO simplifies the process of information reading from such crystals. The satellite peak on glow curve of the anion-defective BeO crystals can be bleached. Furthermore, main dosimetric peak during the satellite bleaching does not change. We suggest that further researches in this field could be interesting for the cases of using detectors, based on BeO monocrystals. Comparisons of some radiation-optical properties of anion-defective crystals of BeO with α-Al2O3 crystals were made. The similar characteristic of TL processes in these crystals was found: reduction of the main peak's TL output and the shifting of the main peak temperature by the increase of heating rate

  19. Antisolvent precipitation of novel xylitol-additive crystals to engineer tablets with improved pharmaceutical performance.

    Science.gov (United States)

    Kaialy, Waseem; Maniruzzaman, Mohammad; Shojaee, Saeed; Nokhodchi, Ali

    2014-12-30

    The purpose of this work was to develop stable xylitol particles with modified physical properties, improved compactibility and enhanced pharmaceutical performance without altering polymorphic form of xylitol. Xylitol was crystallized using antisolvent crystallization technique in the presence of various hydrophilic polymer additives, i.e., polyethylene glycol (PEG), polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA) at a range of concentrations. The crystallization process did not influence the stable polymorphic form or true density of xylitol. However, botryoidal-shaped crystallized xylitols demonstrated different particle morphologies and lower powder bulk and tap densities in comparison to subangular-shaped commercial xylitol. Xylitol crystallized without additive and xylitol crystallized in the presence of PVP or PVA demonstrated significant improvement in hardness of directly compressed tablets; however, such improvement was observed to lesser extent for xylitol crystallized in the presence of PEG. Crystallized xylitols produced enhanced dissolution profiles for indomethacin in comparison to original xylitol. The influence of additive concentration on tablet hardness was dependent on the type of additive, whereas an increased concentration of all additives provided an improvement in the dissolution behavior of indomethacin. Antisolvent crystallization using judiciously selected type and concentration of additive can be a potential approach to prepare xylitol powders with promising physicomechanical and pharmaceutical properties. PMID:25447824

  20. Transmission electron microscopy for the evaluation and optimization of crystal growth

    Energy Technology Data Exchange (ETDEWEB)

    Stevenson, Hilary P.; Lin, Guowu; Barnes, Christopher O.; Sutkeviciute, Ieva; Krzysiak, Troy; Weiss, Simon C.; Reynolds, Shelley; Wu, Ying; Nagarajan, Veeranagu; Makhov, Alexander M.; Lawrence, Robert; Lamm, Emily; Clark, Lisa; Gardella, Timothy J.; Hogue, Brenda G.; Ogata, Craig M.; Ahn, Jinwoo; Gronenborn, Angela M.; Conway, James F.; Vilardaga, Jean-Pierre; Cohen, Aina E.; Calero, Guillermo

    2016-04-26

    The crystallization of protein samples remains the most significant challenge in structure determination by X-ray crystallography. Here, the effectiveness of transmission electron microscopy (TEM) analysis to aid in the crystallization of biological macromolecules is demonstrated. It was found that the presence of well ordered lattices with higher order Bragg spots, revealed by Fourier analysis of TEM images, is a good predictor of diffraction-quality crystals. Moreover, the use of TEM allowed (i) comparison of lattice quality among crystals from different conditions in crystallization screens; (ii) the detection of crystal pathologies that could contribute to poor X-ray diffraction, including crystal lattice defects, anisotropic diffraction and crystal contamination by heavy protein aggregates and nanocrystal nuclei; (iii) the qualitative estimation of crystal solvent content to explore the effect of lattice dehydration on diffraction and (iv) the selection of high-quality crystal fragments for microseeding experiments to generate reproducibly larger sized crystals. Applications to X-ray free-electron laser (XFEL) and micro-electron diffraction (microED) experiments are also discussed.

  1. Transmission electron microscopy for the evaluation and optimization of crystal growth.

    Science.gov (United States)

    Stevenson, Hilary P; Lin, Guowu; Barnes, Christopher O; Sutkeviciute, Ieva; Krzysiak, Troy; Weiss, Simon C; Reynolds, Shelley; Wu, Ying; Nagarajan, Veeranagu; Makhov, Alexander M; Lawrence, Robert; Lamm, Emily; Clark, Lisa; Gardella, Timothy J; Hogue, Brenda G; Ogata, Craig M; Ahn, Jinwoo; Gronenborn, Angela M; Conway, James F; Vilardaga, Jean Pierre; Cohen, Aina E; Calero, Guillermo

    2016-05-01

    The crystallization of protein samples remains the most significant challenge in structure determination by X-ray crystallography. Here, the effectiveness of transmission electron microscopy (TEM) analysis to aid in the crystallization of biological macromolecules is demonstrated. It was found that the presence of well ordered lattices with higher order Bragg spots, revealed by Fourier analysis of TEM images, is a good predictor of diffraction-quality crystals. Moreover, the use of TEM allowed (i) comparison of lattice quality among crystals from different conditions in crystallization screens; (ii) the detection of crystal pathologies that could contribute to poor X-ray diffraction, including crystal lattice defects, anisotropic diffraction and crystal contamination by heavy protein aggregates and nanocrystal nuclei; (iii) the qualitative estimation of crystal solvent content to explore the effect of lattice dehydration on diffraction and (iv) the selection of high-quality crystal fragments for microseeding experiments to generate reproducibly larger sized crystals. Applications to X-ray free-electron laser (XFEL) and micro-electron diffraction (microED) experiments are also discussed. PMID:27139624

  2. Towards protein-crystal centering using second-harmonic generation (SHG) microscopy

    International Nuclear Information System (INIS)

    The potential of second-harmonic generation (SHG) microscopy for automated crystal centering to guide synchrotron X-ray diffraction of protein crystals has been explored. The potential of second-harmonic generation (SHG) microscopy for automated crystal centering to guide synchrotron X-ray diffraction of protein crystals was explored. These studies included (i) comparison of microcrystal positions in cryoloops as determined by SHG imaging and by X-ray diffraction rastering and (ii) X-ray structure determinations of selected proteins to investigate the potential for laser-induced damage from SHG imaging. In studies using β2 adrenergic receptor membrane-protein crystals prepared in lipidic mesophase, the crystal locations identified by SHG images obtained in transmission mode were found to correlate well with the crystal locations identified by raster scanning using an X-ray minibeam. SHG imaging was found to provide about 2 µm spatial resolution and shorter image-acquisition times. The general insensitivity of SHG images to optical scatter enabled the reliable identification of microcrystals within opaque cryocooled lipidic mesophases that were not identified by conventional bright-field imaging. The potential impact of extended exposure of protein crystals to five times a typical imaging dose from an ultrafast laser source was also assessed. Measurements of myoglobin and thaumatin crystals resulted in no statistically significant differences between structures obtained from diffraction data acquired from exposed and unexposed regions of single crystals. Practical constraints for integrating SHG imaging into an active beamline for routine automated crystal centering are discussed

  3. Image analysis study of crystallization in two glass compositions of nuclear interest

    International Nuclear Information System (INIS)

    Few prior studies of the crystallization properties of nuclear glass compositions have focused on the quantification of crystallization rates and the kinetics associated with heat treatments. We have quantified the crystallization of both apatite and powellite in two glass compositions containing simulated fission products using an image analysis technique based on SEM images. Samples are first heat treated at different temperatures (from 600 to 900 C) and for different durations (from 1 h to 388 h). SEM images are then acquired and the image analysis technique is applied to quantify crystallization by extracting a few relevant crystal morphological parameters. These results permit a quantitative comparison of crystallization in the two glass compositions: nature of crystals, morphologies, thermal domains of crystallization, crystallization rates and kinetics are compared. Results show that image analysis is a suitable method when crystals are homogeneously distributed in the glass matrix. However, this technique should be used carefully in the case of a heterogeneous distribution of crystals in the material. (authors)

  4. HIGH-FIELD CRYSTAL GROWTH

    OpenAIRE

    Okuyama, F.

    1986-01-01

    The high-field crystal growth, which refers to crystal growth events occurring on metallic substrates placed in an intense electric field, differs essentially from conventional crystal growths, in that its particle supply process is governed by electrostatic forces. This paper reviews related topics including a recent finding by an industrial research group. The underlying physical processes are also discussed briefly.

  5. Small Business Innovations (Crystal Components)

    Science.gov (United States)

    1991-01-01

    Scientific Materials Corporation, Bozeman, MT developed the SciMax line of improved Nd:Yag crystals under an Small Business Innovation Research (SBIR) contract with Langley Research Center. They reduced the amount of water trapped in the crystals during growth to improve the optical quality and efficiency. Applications of the crystals include fiber optics, telecommunications, welding, drilling, eye surgery and medical instrumentation.

  6. Photo crystallization of lithium iodate

    International Nuclear Information System (INIS)

    It is shown that the processes of crystallization and dissolution of lithium iodate crystals are susceptible to the influence of light. The character of influence of light depends on the solution acidity. A possible mechanism explaining these phenomena is discussed. A technique of growing of lithium iodate crystals at constant temperature, pressure, and volume of the solution is proposed and realized

  7. Quantum dot photonic crystal lasers

    OpenAIRE

    Yoshie, T.; Shchekin, O. B.; Chen, H.; Deppe, D. G.; Scherer, A.

    2002-01-01

    Coupled cavity designs on two-dimensional square lattice photonic crystal slabs were used to demonstrate optically pumped indium arsenide quantum dot photonic crystal lasers at room temperature. Threshold pump powers of 120 and 370 μW were observed for coupled cavities including two and four defect cavities defined in optimised photonic crystals.

  8. Computer simulation of liquid crystals

    International Nuclear Information System (INIS)

    In this thesis computer simulations of liquid crystal systems were performed focusing on the isotropic-nematic interface and on the effects of confinement. A range of idealised and atomistic models were employed using both Monte-Carlo and Molecular Dynamics techniques. The structure of the planar isotropic - nematic (I-N) interface was investigated using constant volume Monte-Carlo simulation of systems of hard-ellipsoids confined between parallel hard walls. The nematic phase is observed to wet the hard walls, establishing two planar I-N interfaces per simulation box. The microscopic pressure tensor in the vicinity of the interface was calculated for both planar and normal alignment of the nematic. The surface tension, calculated directly from the pressure tensor, is lowest in the case of planar alignment indicating that this is the preferred alignment at the interface. The form of the transverse pressure across the interface is dramatically different for the two orientations. For the case of planar alignment we observe a large tension (low transverse pressure) on the nematic side and a small compressive region (high transverse pressure) on the isotropic side. For the case of normal alignment we see a large compression on the nematic side followed by tension on the isotropic side. Comparisons are made with the results of Onsager theory, showing excellent agreement. Gay-Berne particles confined to very thin films are investigated using constant pressure Monte-Carlo simulation. Orientational wetting is again observed at the liquid-wall interface. For homeotropic alignment at the wall we observe strong layering of particles into planes parallel to the walls and long-range orientational order which persists well beyond the range of the fluid-wall interaction. The average system order parameter is strongly dependent on the film thickness, the order being highest when the film thickness is commensurate with the formation of an integral number of molecular layers. An

  9. Generation of Absolute Controlled Crystal Chirality by the Removal of Crystal Water from Achiral Crystal of Nucleobase Cytosine

    OpenAIRE

    Kawasaki, Tsuneomi; Hakoda, Yuko; Mineki, Hiroko; Suzuki, Kenta; Soai, Kenso

    2010-01-01

    The enantioselective formation of chiral crystal of achiral nucleobase cytosine was achieved mediated by the crystal direction selective dehydration of crystal water in the achiral crystal of cytosine monohydrate (P21/c). Heat transfer from the enantiotopic face of the single crystal of cytosine monohydrate afforded the enantiomorphous crystal of anhydrous cytosine.

  10. Co-crystallization of cholesterol and calcium phosphate as related to atherosclerosis

    Science.gov (United States)

    Hirsch, Danielle; Azoury, Reuven; Sarig, Sara

    1990-09-01

    Calcification of atherosclerotic plaques occurs very frequently and aggravates the disease. In biological systems, epitaxial relationships between crystal structures may be important in nucleating the deposit of a solid phase. The biologically preferred calcium phosphate species, apatite, and cholesterol crystal have structurally compatible crystallographic faces which allow epitaxial growth of one crystal upon another. The present study describes a new approach to explore, in vitro, the crystallization processes of calcium phosphate (CaP) with cholesterol (CS) and cholestanol (CN) which are related to atherosclerosis. Aqueous solutions containing calcium and phosphate ions or CaP crystals as hydroxyapatite were added into saturated ethanolic solutions of CS or CS and 10% CN. After precipitation, crystals were collected and analyzed by nuclear magnetic resonance (NMR), infra-red (IR), X-ray, scanning electron microscope (SEM-LINK), differential scanning calorimeter (DSC) and atomic absorption. The principal result is the well-formed crystals precipitation when an aqueous solution and CaP seed crystals were added to saturated solutions of CS and 10% CN. Cholesterol-cholestanol dihydrate (CC2W) crystals precipitated in the presence of CaP seeds were compared to the CC2W crystals obtained without the mineral compound. The results of this comparison indicate a special link between crystals of CaP and CC2W, and support the epitaxial relationship between the two kinds of crystals. The potential of CC2W crystals to be precipitated by CaP seed crystals prove likewise the possible significant role of the cholestanol metabolite in the process of cholesterol crystallization and calcification in the arteries.

  11. Timescales of storage and recycling of crystal mush at Krafla Volcano, Iceland

    Science.gov (United States)

    Cooper, Kari M.; Sims, Kenneth W. W.; Eiler, John M.; Banerjee, Neil

    2016-06-01

    Processes in upper-crustal magma reservoirs such as recharge, magma mixing, recycling of previously crystallized material, and eruption affect both the physical state and the chemical composition of magmas. A growing body of evidence shows that crystals in intermediate or silicic volcanic rocks preserve records of these processes that may be obscured due to mixing in the liquid fraction of magmas. Fewer studies have focused on crystals in basaltic lavas, but these show evidence for a more subtle, but still rich record of magmatic processes. We present new 238U-230Th-226Ra data for plagioclase, combined with δ18O and trace-element measurements of the same crystal populations, from basalts erupted at Krafla Volcanic Center, Iceland. These data document the presence of multiple crystal populations within each sample, with chemical and oxygen isotope heterogeneity at a variety of scales: within individual crystals, between crystals in a given population, between crystal populations within the same sample, and between crystals in lavas erupted from different vents during the same eruption. Comparison to whole-rock or groundmass data shows that the majority of macroscopic crystals are not in trace-element or oxygen isotope equilibrium with their host liquids. The most likely explanation for these data is that the macroscopic crystals originated within a highly heterogeneous crystal mush in the shallow magma reservoir system. U-series and diffusion data indicate that the crystals (and therefore the mush) formed recently (likely within a few thousand years of eruption, and with a maximum age of 8-9 ka), and that the crystals resided in their host magma prior to eruption for decades to a few centuries at most. These data, in conjunction with other recent studies, suggest a model where erupted Icelandic magmas are the result of diverse magmas entering the crust, followed by complex interactions between melts and previously crystallized material at all crustal levels.

  12. Liquid crystal orientation control in photonic liquid crystal fibers

    Science.gov (United States)

    Chychlowski, M. S.; Nowinowski-Kruszelnicki, E.; Woliński, T. R.

    2011-05-01

    Similarly to liquid crystal displays technology in photonic liquid crystal fibers (PLCFs) a molecular orientation control is a crucial issue that influences proper operation of PLCF-based devices. The paper presents two distinct configurations: planar and radial escaped orientation of the LC molecules inside capillaries as well as methods of their application to photonic liquid crystal fibers. Possibilities of LC orientation control influence both: attenuation and transmitting spectra of the PLCF The orienting method is based on creation of an additional orienting layer on the inner surface of the capillary or air hole of the photonic liquid crystal fiber. Aligning materials used in the experiment are commercially available polyimides SE1211 and SE130 which induce liquid crystal homeotropic and planar anchoring conditions. The orienting layer increase an order parameter of the liquid crystal improving propagation properties and stability of photonic liquid crystal fiber-based devices.

  13. Modelisation and numerical simulation for bulk crystal growth processes

    Energy Technology Data Exchange (ETDEWEB)

    Duffar, F.; Dusserre, P.; Barat, C.; Nabot, J.P.

    1993-12-31

    The aim of this work is to study the relevance of numerical simulation for improving the process control in the field of crystal growth. This investigation focused on the growth of semiconductor and halide crystals by the Bridgman solidification technique, the principle of which is to cool a seeded feed material contained in a crucible, either by pulling the crucible or by decreasing the temperature in the furnace. Calculations are performed with the finite element method, and for comparison, experiments are carried out on Bridgman pulling machines operating either in a laboratory or in industrial plants. Calculations and experimental data have shown a good agreement and a satisfactory reliability.

  14. Mechanism of Germanium-Induced Perimeter Crystallization of Amorphous Silicon

    OpenAIRE

    Hakim, M. M. A.; Ashburn, P.

    2007-01-01

    We report a study aimed at highlighting the mechanism of a new amorphous silicon crystallization phenomenon that originates from the perimeter of a germanium layer during low-temperature annealing (500°C). Results are reported on doped and undoped amorphous silicon films, with thicknesses in the range 40–200 nm, annealed at a temperature of 500 or 550°C. A comparison is made of crystallization arising from Ge and SiGe layers and the role of damage from a high-dose fluorine implant is investig...

  15. Band structures and localization properties of aperiodic layered phononic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Yan Zhizhong, E-mail: zzyan@bit.edu.cn [Department of Applied Mathematics, Beijing Institute of Technology, Beijing 100081 (China); Zhang Chuanzeng [Department of Civil Engineering, University of Siegen, D-57078 Siegen (Germany)

    2012-03-15

    The band structures and localization properties of in-plane elastic waves with coupling of longitudinal and transverse modes oblique propagating in aperiodic phononic crystals based on Thue-Morse and Rudin-Shapiro sequences are studied. Using transfer matrix method, the concept of the localization factor is introduced and the correctness is testified through the Rytov dispersion relation. For comparison, the perfect periodic structure and the quasi-periodic Fibonacci system are also considered. In addition, the influences of the random disorder, local resonance, translational and/or mirror symmetries on the band structures of the aperiodic phononic crystals are analyzed in this paper.

  16. Modelisation and numerical simulation for bulk crystal growth processes

    International Nuclear Information System (INIS)

    The aim of this work is to study the relevance of numerical simulation for improving the process control in the field of crystal growth. This investigation focused on the growth of semiconductor and halide crystals by the Bridgman solidification technique, the principle of which is to cool a seeded feed material contained in a crucible, either by pulling the crucible or by decreasing the temperature in the furnace. Calculations are performed with the finite element method, and for comparison, experiments are carried out on Bridgman pulling machines operating either in a laboratory or in industrial plants. Calculations and experimental data have shown a good agreement and a satisfactory reliability

  17. Social Comparison Seeking: Providing General Comparison Curtails Local Comparison

    Science.gov (United States)

    Buckingham, Justin T.; Zell, Ethan; Schurtz, David R.

    2012-01-01

    Past research shows that people use local social comparison information more than general social comparison information when both are given (Zell & Alicke, 2010). The present studies examined the extent to which people seek local comparisons when they have already received general comparison information. In Study 1, students received their exam…

  18. Optimization of crystal extraction experiment

    OpenAIRE

    Biryukov, Valery

    2001-01-01

    Using a computer model for the crystal extraction, we investigate the bent-crystal parameters optimal for the extraction experiment. The optimal crystal curvature is found to be near 1 GeV/cm (for pv/R), i.e. a factor of 2--3 higher than for the crystal application in beam lines. An influence of the accelerator optics on extraction is discussed. A possibility of using the high-Z crystals for extraction is considered. The simulations for the ongoing experiments at the CERN-SPS and the Fermilab...

  19. Crystal morphology of simonkolleite (Zn5(OH)8Cl2.H2O): a SEM study

    International Nuclear Information System (INIS)

    In this paper the morphology of natural and synthetic simonkolleite crystals is investigated. We use an approach of determining the Miller indices of the faces of crystals with electron-microscopic dimensions by comparing their SEM photographs with model images generated by the computer program VESTA. The morphological importance of the crystallographic forms of simonkolleite was estimated on the basis of Bravais–Friedel–Donnay–Harker law and the theory of PBC-vectors. Model images of the crystals were obtained by the introduction of lattice parameters, space groups and the indices of the morphologically important forms. The program VESTA allows for the obtention of projections of the model image in stochastic orientations and for a very precise comparison with the image of the real crystal. It was found that the studied simonkolleite crystals are formed from basal pinacoid {001} and rhombohedrons {101} and {012}. Key words: simonkolleite, crystal morphology, Miller indices

  20. Phase transitions in KDP crystals with the complex organic and inorganic impurities

    Directory of Open Access Journals (Sweden)

    B.Strukov

    2007-01-01

    Full Text Available In this paper we present the results of the study of dielectric and thermal properties of KDP crystals doped with different complex organic and inorganic molecules which decorate different (pyramidal or prismatic crystal growth sectors. It is shown that the properties of stained and transparent parts of the crystal in comparison with the corresponding parts of the nominally pure crystal are different for KDP crystals grown by means of traditional (slow and rapid growth technique. The difference of the domain contribution into dielectric constant of the polar phase and its characteristic hysteresis in pure and dyed crystals, transition temperature position, form of the specific heat anomaly are presented and analyzed. The most probable model of incorporation of the complex impurity molecules into KDP structure is proposed.

  1. The influence of microgravity on the growth of Ga Sb crystals

    International Nuclear Information System (INIS)

    Bridgman method was applied, for growing a GaSb crystal under Micro-gravity condition (MG), on the cosmic orbital station ''Mir'' during the cosmic Syrian-Soviet flight. The mentioned experiment was called ''Aphamia'' and was carried out using furnace ''Crystall''. The same experiment was simultaneously carried out at laboratory condition in order to compare obtained crystals and to determine the influence of MG on the growth of GaSb crystal. During this experiment the growth of GaSb crystal with a given conductivity under Earth and MG conditions was performed. The crystal structure, impurity distribution and electro-physical properties of GaSb, were investigated. A comparison with available data in literature is also provided. (author)

  2. The Dark Crystal

    OpenAIRE

    Kurelić, Zoran

    1997-01-01

    Hannah Arendt presented her understanding of totalitarianism in the book The Origins of Totalitarianism, but she realized that the word origin does not really fit into her narrative and started talking about the elements of totalitarianism; the elements which crystallized into totalitarian regimes. Unfortunately that does not solve the problem because Nazism and Stalinism do not share a set of elements. The author presents and discusses the logic of Arendt’s narrative which wants to connect t...

  3. Modelling of crystallizer wear

    OpenAIRE

    J. David; P. Švec; R. Frischer

    2012-01-01

    Purpose: In this paper will be described an analysis of control problems and technical lifetime modeling of continuous casting device crystallizers. A full exploitation of continuous casting equipment (CCE) advantages can only be achieved through a control system that minimizes all undesirable effects on the technological process. Some of the undesirable effects influencing the CCE process effectiveness are the failures and service interruptions. The failures and service interruptions are cau...

  4. Photonic Crystal Optical Tweezers

    OpenAIRE

    Wilson, Benjamin K.; Mentele, Tim; Bachar, Stephanie; Knouf, Emily; Bendoraite, Ausra; Tewari, Muneesh; Pun, Suzie H.; Lin, Lih Y.

    2009-01-01

    Non-invasive optical manipulation of particles has emerged as a powerful and versatile tool for biological study and nanotechnology. In particular, trapping and rotation of cells, cell nuclei and sub-micron particles enables unique functionality for various applications such as tissue engineering, cancer research and nanofabrication. We propose and demonstrate a purely optical approach to rotate and align particles using the interaction of polarized light with photonic crystal nanostructures ...

  5. Hydrophobic photonic crystal fibers.

    Science.gov (United States)

    Xiao, Limin; Birks, T A; Loh, W H

    2011-12-01

    We propose and demonstrate hydrophobic photonic crystal fibers (PCFs). A chemical surface treatment for making PCFs hydrophobic is introduced. This repels water from the holes of PCFs, so that their optical properties remain unchanged even when they are immersed in water. The combination of a hollow core and a water-repellent inner surface of the hydrophobic PCF provides an ultracompact dissolved-gas sensor element, which is demonstrated for the sensing of dissolved ammonia gas. PMID:22139276

  6. Crystals against cancer

    CERN Multimedia

    2009-01-01

    This is a remarkable example of direct technology transfer from particle physics to medicine. Clinical trials have begun in Portugal on a new medical imaging system for the diagnosis of breast cancer, which uses positron emission tomography (PET). The system, developed by a Portuguese consortium in collaboration with CERN and laboratories participating in the Crystal Clear collaboration, will detect even the smallest tumours and thus help avoid unnecessary biopsies.

  7. Variable frequency photonic crystals

    CERN Document Server

    Wu, Xiang-Yao; Liu, Xiao-Jing; Yang, Jing-Hai; Li, Hong; Chen, Wan-Jin

    2015-01-01

    In this paper, we have firstly proposed a new one-dimensional variable frequency photonic crystals (VFPCs), and calculated the transmissivity and the electronic field distribution of VFPCs with and without defect layer, and considered the effect of defect layer and variable frequency function on the transmissivity and the electronic field distribution. We have obtained some new characteristics for the VFPCs, which should be help to design a new type optical devices.

  8. Nematic liquid crystal bridges

    Science.gov (United States)

    Doss, Susannah; Ellis, Perry; Vallamkondu, Jayalakshmi; Danemiller, Edward; Vernon, Mark; Fernandez-Nieves, Alberto

    We study the effects of confining a nematic liquid crystal between two parallel glass plates with homeotropic boundary conditions for the director at all bounding surfaces. We find that the free surface of the nematic bridge is a surface of constant mean curvature. In addition, by changing the distance between the plates and the contact angle with the glass plates, we transition between loops and hedgehogs that can be either radial or hyperbolic.

  9. Textures of liquid crystals

    CERN Document Server

    Dierking, Ingo

    2006-01-01

    A unique compendium of knowledge on all aspects of the texture of liquid crystals, providing not just detailed information on texture formation and determination, but also an in-depth discussion of different characterization methods. Experts as well as graduates entering the field will find all the information they need in this handbook, while the magnitude of the color images make it valuable hands-on-reference.

  10. Crystal structure of benzobicyclon

    Directory of Open Access Journals (Sweden)

    Gihaeng Kang

    2015-12-01

    Full Text Available In the title compound, C22H19ClO4S2 [systematic name: 3-(2-chloro-4-mesylbenzoyl-4-(phenylsulfanylbicyclo[3.2.1]oct-3-en-2-one], which is an unclassified herbicide, the dihedral angle between the plane of the phenyl and chlorobenzene rings is 19.9 (2°. In the crystal, C—H...O hydrogen bonds link adjacent molecules, generating two-dimensional networks extending parellel to (011.

  11. Sonic Crystal Noise Barriers

    OpenAIRE

    Chong, Yung

    2012-01-01

    An alternative road traffic noise barrier using an array of periodically arranged vertical cylinders known as a Sonic Crystal (SC) is investigated. As a result of multiple (Bragg) scattering, SCs exhibit a selective sound attenuation in frequency bands called band gaps or stop bands related to the spacing and size of the cylinders. Theoretical studies using Plane Wave Expansion (PWE), Multiple Scattering Theory (MST) and Finite Element Method (FEM) have enabled study of the performance of SC ...

  12. Liquid Crystal Motion Picture Projector①

    Institute of Scientific and Technical Information of China (English)

    SHIYongji

    1997-01-01

    A liquid crystal moving picture projector and method are described.Light incident on a liquid crystal display-type device is selectively scattered or transmitted by respective portions of liquid crystal display,and a projection mechanism projects an image formed by either such scattered light or such transmitted light.A liquid cystal moving picture projector includes a liquid crystal display for creating characteristics of an image,and projecttion optics for projecting images sequentially created by the display.The display includes a liquid crystal material capable of temporary storing information at respective areas.The temporary storage may be a function of charge storing directly on liquid crystal material.A method of projecting plural images in sequence includes:creating an image or characteristics of an image in a liquid crystal material,storing such image in such liquid crystal material,directing light at such liquid crystal material,projecting such image as a function of light transmitted through or scattered by such liquid crystal material,and creating a further image in such liquid crystal material for subsequent projection.

  13. High density protein crystal growth

    Science.gov (United States)

    Rouleau, Robyn (Inventor); Delucas, Lawrence (Inventor); Hedden, Douglas Keith (Inventor)

    2004-01-01

    A protein crystal growth assembly including a crystal growth cell and further including a cell body having a top side and a bottom side and a first aperture defined therethrough, the cell body having opposing first and second sides and a second aperture defined therethrough. A cell barrel is disposed within the cell body, the cell barrel defining a cavity alignable with the first aperture of the cell body, the cell barrel being rotatable within the second aperture. A reservoir is coupled to the bottom side of the cell body and a cap having a top side is disposed on the top side of the cell body. The protein crystal growth assembly may be employed in methods including vapor diffusion crystallization, liquid to liquid crystallization, batch crystallization, and temperature induction batch mode crystallization.

  14. 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.

  15. Slotted Photonic Crystal Sensors

    Directory of Open Access Journals (Sweden)

    Andrea Di Falco

    2013-03-01

    Full Text Available Optical biosensors are increasingly being considered for lab-on-a-chip applications due to their benefits such as small size, biocompatibility, passive behaviour and lack of the need for fluorescent labels. The light guiding mechanisms used by many of them results in poor overlap of the optical field with the target molecules, reducing the maximum sensitivity achievable. This review article presents a new platform for optical biosensors, namely slotted photonic crystals, which provide higher sensitivities due to their ability to confine, spatially and temporally, the optical mode peak within the analyte itself. Loss measurements showed values comparable to standard photonic crystals, confirming their ability to be used in real devices. A novel resonant coupler was designed, simulated, and experimentally tested, and was found to perform better than other solutions within the literature. Combining with cavities, microfluidics and biological functionalization allowed proof-of-principle demonstrations of protein binding to be carried out. Higher sensitivities were observed in smaller structures than possible with most competing devices reported in the literature. This body of work presents slotted photonic crystals as a realistic platform for complete on-chip biosensing; addressing key design, performance and application issues, whilst also opening up exciting new ideas for future study.

  16. Quartz crystal fabrication facility

    Science.gov (United States)

    Ney, R. J.

    1980-05-01

    The report describes the design and operation of a five chamber, interconnected vacuum system, which is capable of cleaning, plating, and sealing precision quartz crystal units in ceramic flatpack enclosures continuously in a high vacuum environment. The production rate design goal was 200 units per eight hour day. A unique nozzle beam gold deposition source was developed to operate for extended periods of time without reloading. The source puts out a narrow beam of gold typically in the order of 2 1/2 deg included cone angle. Maximum deposition rates are in the order of 400 a/min at 5.5 in. 'throw' distance used. Entrance and exit air lock chambers expedite the material throughput, so that the processing chambers are at high vacuum for extended periods of time. A stainless steel conveyor belt, in conjunction with three vacuum manipulators, transport the resonator components to the various work stations. Individual chambers are normally separated from each other by gate valves. The crystal resonators, mounted in flatpack frames but unplated, are loaded into transport trays in a lid-frame-lid sequency for insertion into the system and exit as completed crystal units. The system utilizes molybdenum coated ball bearings at essentially all friction surfaces. The gold sources and plating mask heads are equipped with elevators and gate valves, so that they can be removed from the system for maintenance without exposing the chambers to atmosphere.

  17. Living liquid crystals.

    Science.gov (United States)

    Zhou, Shuang; Sokolov, Andrey; Lavrentovich, Oleg D; Aranson, Igor S

    2014-01-28

    Collective motion of self-propelled organisms or synthetic particles, often termed "active fluid," has attracted enormous attention in the broad scientific community because of its fundamentally nonequilibrium nature. Energy input and interactions among the moving units and the medium lead to complex dynamics. Here, we introduce a class of active matter--living liquid crystals (LLCs)--that combines living swimming bacteria with a lyotropic liquid crystal. The physical properties of LLCs can be controlled by the amount of oxygen available to bacteria, by concentration of ingredients, or by temperature. Our studies reveal a wealth of intriguing dynamic phenomena, caused by the coupling between the activity-triggered flow and long-range orientational order of the medium. Among these are (i) nonlinear trajectories of bacterial motion guided by nonuniform director, (ii) local melting of the liquid crystal caused by the bacteria-produced shear flows, (iii) activity-triggered transition from a nonflowing uniform state into a flowing one-dimensional periodic pattern and its evolution into a turbulent array of topological defects, and (iv) birefringence-enabled visualization of microflow generated by the nanometers-thick bacterial flagella. Unlike their isotropic counterpart, the LLCs show collective dynamic effects at very low volume fraction of bacteria, on the order of 0.2%. Our work suggests an unorthodox design concept to control and manipulate the dynamic behavior of soft active matter and opens the door for potential biosensing and biomedical applications. PMID:24474746

  18. On dewetting of thin films due to crystallization (crystallization dewetting).

    Science.gov (United States)

    Habibi, Mehran; Rahimzadeh, Amin; Eslamian, Morteza

    2016-03-01

    Drying and crystallization of a thin liquid film of an ionic or a similar solution can cause dewetting in the resulting thin solid film. This paper aims at investigating this type of dewetting, herein termed "crystallization dewetting", using PbI2 dissolved in organic solvents as the model solution. PbI2 solid films are usually used in X-ray detection and lead halide perovskite solar cells. In this work, PbI2 films are fabricated using spin coating and the effect of major parameters influencing the crystallization dewetting, including the type of the solvent, solution concentration, drying temperature, spin speed, as well as imposed vibration on the substrate are studied on dewetting, surface profile and coverage, using confocal scanning laser microscopy. Simplified hydrodynamic governing equations of crystallization in thin films are presented and using a mathematical representation of the process, it is phenomenologically demonstrated that crystallization dewetting occurs due to the absorption and consumption of the solution surrounding a growing crystal. Among the results, it is found that a low spin speed (high thickness), a high solution concentration and a low drying temperature promote crystal growth, and therefore crystallization dewetting. It is also shown that imposed vibration on the substrate can affect the crystal size and crystallization dewetting. PMID:26993991

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

    Institute of Scientific and Technical Information of China (English)

    Duan Li; Kang Qi

    2008-01-01

    This paper reports that an optical diagnostic system consisting of Maeh-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 theoutcome 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.

  20. High-heat-load synchrotron tests of room-temperature, silicon crystal monochromators at the CHESS F-2 wiggler station

    International Nuclear Information System (INIS)

    This note summarizes the results of the single crystal monochromator high-heat-load tests performed at the CHESS F-2 wiggler station. The results from two different cooling geometries are presented: (1) the ''pin-post'' crystal and (2) the ''criss-cross'' crystal. The data presented were taken in August 1993 (water-cooled pin-post) and in April 1995 (water- and gallium-cooled pin-post crystal and gallium-cooled criss-cross crystal). The motivation for trying these cooling (or heat exchanger) geometries is to improve the heat transfer efficiency over that of the conventional slotted crystals. Calculations suggest that the pin-post or the microchannel design can significantly improve the thermal performance of the crystal. The pin-post crystal used here was fabricated by Rocketdyne Albuquerque Operations. From the performance of the conventional slotted crystals, it was thought that increased turbulence in the flow pattern may also enhance the heat transfer. The criss-cross crystal was a simple attempt to achieve the increased flow turbulence. The criss-cross crystal was partly fabricated in-house (cutting, etching and polishing) and bonded by RAO. Finally, a performance comparison among all the different room temperature silicon monochromators that have been tested by the APS is presented. The data includes measurements with the slotted crystal and the core-drilled crystals. Altogether, the data presented here were taken at the CHESS F-2 wiggler station between 1991 and 1995

  1. Discrete breathers in crystals

    Science.gov (United States)

    Dmitriev, S. V.; Korznikova, E. A.; Baimova, Yu A.; Velarde, M. G.

    2016-05-01

    It is well known that periodic discrete defect-containing systems, in addition to traveling waves, support vibrational defect-localized modes. It turned out that if a periodic discrete system is nonlinear, it can support spatially localized vibrational modes as exact solutions even in the absence of defects. Since the nodes of the system are all on equal footing, it is only through the special choice of initial conditions that a group of nodes can be found on which such a mode, called a discrete breather (DB), will be excited. The DB frequency must be outside the frequency range of the small-amplitude traveling waves. Not resonating with and expending no energy on the excitation of traveling waves, a DB can theoretically conserve its vibrational energy forever provided no thermal vibrations or other perturbations are present. Crystals are nonlinear discrete systems, and the discovery in them of DBs was only a matter of time. It is well known that periodic discrete defect-containing systems support both traveling waves and vibrational defect-localized modes. It turns out that if a periodic discrete system is nonlinear, it can support spatially localized vibrational modes as exact solutions even in the absence of defects. Because the nodes of the system are all on equal footing, only a special choice of the initial conditions allows selecting a group of nodes on which such a mode, called a discrete breather (DB), can be excited. The DB frequency must be outside the frequency range of small-amplitude traveling waves. Not resonating with and expending no energy on the excitation of traveling waves, a DB can theoretically preserve its vibrational energy forever if no thermal vibrations or other perturbations are present. Crystals are nonlinear discrete systems, and the discovery of DBs in them was only a matter of time. Experimental studies of DBs encounter major technical difficulties, leaving atomistic computer simulations as the primary investigation tool. Despite

  2. Functionalizing Designer DNA Crystals

    Science.gov (United States)

    Chandrasekaran, Arun Richard

    Three-dimensional crystals have been self-assembled from a DNA tensegrity triangle via sticky end interaction. The tensegrity triangle is a rigid DNA motif containing three double helical edges connected pair-wise by three four-arm junctions. The symmetric triangle contains 3 unique strands combined in a 3:3:1 ratio: 3 crossover, 3 helical and 1 central. The length of the sticky end reported previously was two nucleotides (nt) (GA:TC) and the motif with 2-helical turns of DNA per edge diffracted to 4.9 A at beam line NSLS-X25 and to 4 A at beam line ID19 at APS. The purpose of these self-assembled DNA crystals is that they can be used as a framework for hosting external guests for use in crystallographic structure solving or the periodic positioning of molecules for nanoelectronics. This thesis describes strategies to improve the resolution and to incorporate guests into the 3D lattice. The first chapter describes the effect of varying sticky end lengths and the influence of 5'-phosphate addition on crystal formation and resolution. X-ray diffraction data from beam line NSLS-X25 revealed that the crystal resolution for 1-nt (G:C) sticky end was 3.4 A. Motifs with every possible combination of 1-nt and 2-nt sticky-ended phosphorylated strands were crystallized and X-ray data were collected. The position of the 5'-phosphate on either the crossover (strand 1), helical (strand 2), or central strand (3) had an impact on the resolution of the self-assembled crystals with the 1-nt 1P-2-3 system diffracting to 2.62 A at APS and 3.1 A at NSLS-X25. The second chapter describes the sequence-specific recognition of DNA motifs with triplex-forming oligonucleotides (TFOs). This study examined the feasibility of using TFOs to bind to specific locations within a 3-turn DNA tensegrity triangle motif. The TFO 5'-TTCTTTCTTCTCT was used to target the tensegrity motif containing an appropriately embedded oligopurine.oligopyrimidine binding site. As triplex formation involving cytidine

  3. Investigations on the growth, optical, thermal, dielectric, and laser damage threshold properties of crystal violet dye-doped potassium acid phthalate single crystal

    Science.gov (United States)

    Rao, G. Babu; Rajesh, P.; Ramasamy, P.

    2016-03-01

    Influence of crystal violet dye with different concentration on potassium acid phthalate single crystal grown by conventional method has been studied. No change has been observed in the structure, whereas changes have been observed in the external morphology of the crystal when the dyes are incorporated in the crystal lattice. Thermogravimetric and differential thermal analyses show the onset decomposition temperatures to be at 302, 285, 284, and 285 °C for pure, 0.1, 0.3, and 0.5 mol% crystal violet-doped potassium acid phthalate crystals, respectively. The dielectric measurement was carried out on the grown crystals as a function of frequency at various temperatures. In addition, strong luminescent emission bands at 638, 648, and 640 nm were observed in which the relative intensity was found to be reversed as a result of doping concentration. The laser damage threshold value significantly increased for dye-doped crystal in comparison with pure crystal which may make it suitable for the solid-state dye laser applications.

  4. Unifying the crystallization behavior of hexagonal and square crystals with the phase-field-crystal model

    Science.gov (United States)

    Tao, Yang; Zheng, Chen; Jing, Zhang; Yongxin, Wang; Yanli, Lu

    2016-03-01

    By employing the phase-field-crystal models, the atomic crystallization process of hexagonal and square crystals is investigated with the emphasis on the growth mechanism and morphological change. A unified regime describing the crystallization behavior of both crystals is obtained with the thermodynamic driving force varying. By increasing the driving force, both crystals (in the steady-state) transform from a faceted polygon to an apex-bulged polygon, and then into a symmetric dendrite. For the faceted polygon, the interface advances by a layer-by-layer (LL) mode while for the apex-bulged polygonal and the dendritic crystals, it first adopts the LL mode and then transits into the multi-layer (ML) mode in the later stage. In particular, a shift of the nucleation sites from the face center to the area around the crystal tips is detected in the early growth stage of both crystals and is rationalized in terms of the relation between the crystal size and the driving force distribution. Finally, a parameter characterizing the complex shape change of square crystal is introduced. Project supported by the National Natural Science Foundation of China (Grant Nos. 54175378, 51474176, and 51274167), the Natural Science Foundation of Shaanxi Province, China (Grant No. 2014JM7261), and the Doctoral Foundation Program of Ministry of China (Grant No. 20136102120021).

  5. Third harmonic frequency generation by type-I critically phase-matched LiB3O5 crystal by means of optically active quartz crystal.

    Science.gov (United States)

    Gapontsev, Valentin P; Tyrtyshnyy, Valentin A; Vershinin, Oleg I; Davydov, Boris L; Oulianov, Dmitri A

    2013-02-11

    We present a method of third harmonic generation at 355 nm by frequency mixing of fundamental and second harmonic radiation of an ytterbium nanosecond pulsed all-fiber laser in a type-I phase-matched LiB(3)O(5) (LBO) crystal where originally orthogonal polarization planes of the fundamental and second harmonic beams are aligned by an optically active quartz crystal. 8 W of ultraviolet light at 355 nm were achieved with 40% conversion efficiency from 1064 nm radiation. The conversion efficiency obtained in a type-I phase-matched LBO THG crystal was 1.6 times higher than the one achieved in a type-II LBO crystal at similar experimental conditions. In comparison to half-wave plates traditionally used for polarization alignment the optically active quartz crystal has much lower temperature dependence and requires simpler optical alignment. PMID:23481827

  6. Principles of crystallization, and methods of single crystal growth

    International Nuclear Information System (INIS)

    Most of single crystals (monocrystals), have distinguished optical, electrical, or magnetic properties, which make from single crystals, key elements in most of technical modern devices, as they may be used as lenses, Prisms, or grating sin optical devises, or Filters in X-Ray and spectrographic devices, or conductors and semiconductors in electronic, and computer industries. Furthermore, Single crystals are used in transducer devices. Moreover, they are indispensable elements in Laser and Maser emission technology.Crystal Growth Technology (CGT), has started, and developed in the international Universities and scientific institutions, aiming at some of single crystals, which may have significant properties and industrial applications, that can attract the attention of international crystal growth centers, to adopt the industrial production and marketing of such crystals. Unfortunately, Arab universities generally, and Syrian universities specifically, do not give even the minimum interest, to this field of Science.The purpose of this work is to attract the attention of Crystallographers, Physicists and Chemists in the Arab universities and research centers to the importance of crystal growth, and to work on, in the first stage to establish simple, uncomplicated laboratories for the growth of single crystal. Such laboratories can be supplied with equipment, which are partly available or can be manufactured in the local market. Many references (Articles, Papers, Diagrams, etc..) has been studied, to conclude the most important theoretical principles of Phase transitions,especially of crystallization. The conclusions of this study, are summarized in three Principles; Thermodynamic-, Morphologic-, and Kinetic-Principles. The study is completed by a brief description of the main single crystal growth methods with sketches, of equipment used in each method, which can be considered as primary designs for the equipment, of a new crystal growth laboratory. (author)

  7. Peculiarities of electron excitations decay in ion-molecular crystals

    International Nuclear Information System (INIS)

    Ionic-molecular crystals (IMC) have wide application in various optical devices. Its are using in capacity of solid state dosimetric materials and isolators. Peculiarities of chemical and energetic states of IMC lead to following number of features of electron excitation decay in comparison with alkaline-halogen crystals: - both an electrons and a holes simultaneously could be captured and localized either on anion or on cation complexes; - in-molecular forces arising in result of charge capture could conduct to decay of anion or cation complex; - decay products od anion or cation complex could participate in following reaction of new products formation. All these processes and new products of electron excitation decay exert strong effect on optical, magnetic and electrical characteristics of IMC. Knowledge of way and mechanisms of electron excitation decay in IMC could allow to control of radiation stability of crystals with help of impurities participating in different channels of solid state reactions

  8. Sedimentation analysis of small ice crystals by Lattice Boltzmann Method

    CERN Document Server

    Giovacchini, Juan P

    2016-01-01

    Lattice Boltzmann Method (LBM) is used to simulate and analyze the sedimentation of small ($16-80 \\,\\mu m$) ice particles in the atmosphere. We are specially interested in evaluating the terminal falling velocity for two ice particle shapes: columnar ice crystals and six bullet-rosettes ice policrystal. The main objective in this paper is to investigate the LBM suitability to solve ice crystal sedimentation problems, as well as to evaluate these numerical methods as a powerful numerical tool to solve these problems for arbitrary ice crystal shapes and sizes. LBM results are presented in comparison with laboratory experimental results and theoretical proposals well known in the literature. The numerical results show good agreement with experimental and theoretical results for both geometrical configurations.

  9. Crystal growth and structural analysis of zirconium sulphoselenide single crystals

    Indian Academy of Sciences (India)

    K R Patel; R D Vaidya; M S Dave; S G Patel

    2008-08-01

    A series of zirconium sulphoselenide (ZrSSe3–, where = 0, 0.5, 1, 1.5, 2, 2.5, 3) single crystals have been grown by chemical vapour transport technique using iodine as a transporting agent. The optimum condition for the growth of these crystals is given. The stoichiometry of the grown crystals were confirmed on the basis of energy dispersive analysis by X-ray (EDAX) and the structural characterization was accomplished by X-ray diffraction (XRD) studies. The crystals are found to possess monoclinic structure. The lattice parameters, volume, particle size and X-ray density have been carried out for these crystals. The effect of sulphur proportion on the lattice parameter, unit cell volume and X-ray density in the series of ZrSSe3– single crystals have been studied and found to decrease in all these parameters with rise in sulphur proportion. The grown crystals were examined under optical zoom microscope for their surface topography study. Hall effect measurements were carried out on grown crystals at room temperature. The negative value of Hall coefficient implies that these crystals are -type in nature. The conductivity is found to decrease with increase of sulphur content in the ZrSSe3– series. The electrical resistivity parallel to c-axis as well as perpendicular to -axis have been carried out in the temperature range 303–423 K. The results obtained are discussed in detail.

  10. Hardness of metallic crystals

    Indian Academy of Sciences (India)

    Wuhui Li; Fengzhang Ren; Juanhua Su; Zhanhong Ma; Ke Cao; Baohong Tian

    2011-07-01

    This paper presents a new formula for calculating the hardness of metallic crystals, resulted from the research on the critical grain size with stable dislocations. The formula is = 6 /[(1 – )], where is the hardness, the coefficient, the shear modulus, the Poisson’s ratio, a function of the radius of an atom () and the electron density at the atom interface (). The formula will not only be used to testify the critical grain size with stable dislocations, but also play an important role in the understanding of mechanical properties of nanocrystalline metals.

  11. Dual crystal scintillation probe

    International Nuclear Information System (INIS)

    A scintillation probe is described which employs two scintillation detectors having partially overlapping fields of view. The overlapping fields of view allow radioactive events from a particular spatial region to be identified and tabulated separately. Preferably, one crystal is annularly positioned with respect to the other and is collimated so that radioactive events from the left ventricle of the human heart can be isolated to a large extent from simultaneous background. Useful cardiac information is obtained in a non-invasive technique of medical examination of living patients requiring only a single injection of a radioisotope

  12. Crystal structure of triclopyr

    OpenAIRE

    Seonghwa Cho; Jineun Kim; Youngeun Jeon; Tae Ho Kim

    2014-01-01

    In the title compound {systematic name: 2-[(3,5,6-trichloropyridin-2-yl)oxy]acetic acid}, the herbicide triclopyr, C7H4Cl3NO3, the asymmetric unit comprises two independent molecules in which the dihedral angles between the mean plane of the carboxylic acid group and the pyridyl ring plane are 79.3 (6) and 83.8 (5)°. In the crystal, pairs of intermolecular O—H...O hydrogen bonds form dimers through an R22(8) ring motif and are extended into chains along [100] by weak π–π interactions [ring ce...

  13. Crystal structure of cafenstrole

    Directory of Open Access Journals (Sweden)

    Gihaeng Kang

    2015-08-01

    Full Text Available The title compound (systematic name: N,N-diethyl-3-mesitylsulfonyl-1H-1,2,4-triazole-1-carboxamide, C16H22N4O3S, is a triazole herbicide. The dihedral angle between the planes of the triazole and benzene ring planes is 88.14 (10°. In the crystal, C—H...O hydrogen bonds and weak C—H...π interactions link adjacent molecules, forming one-dimensional chains along the a axis.

  14. Antiferroelectric liquid crystals

    OpenAIRE

    Benguigui, L.; Hardouin, F.

    1981-01-01

    Dielectric investigations have been undertaken in two thermotropic liquid crystal systems exhibiting a smectic A2 phase (i.e. with the layer spacing equal to twice the molecular length). The postulated antiferroelectric ordering has been supported by these measurements. There are anomalies in the dielectric constants ε∥ and ε〉 at the N-S A2 transition and an unusual low frequency relaxation, with a slight temperature dependence, appears around this transition and in the S A phases of these sy...

  15. Crystal structure of pencycuron

    OpenAIRE

    Gihaeng Kang; Jineun Kim; Eunjin Kwon; Tae Ho Kim

    2015-01-01

    In the title compound [systematic name: 1-(4-chlorobenzyl)-1-cyclopentyl-3-phenylurea], C19H21ClN2O, which is a urea fungicide, the cyclopentyl ring adopts an envelope conformation, with one of the methylene C atoms adjacent to the C atom bonding to the N atom as the flap. The dihedral angles between the mean planes of the central cyclopentyl ring (all atoms) and the chlorobenzyl and phenyl rings are 77.96 (6) and 57.77 (7)°, respectively. In the crystal, N—H...O hydrogen bonds link adjacent ...

  16. Crystal structure of fenclorim

    OpenAIRE

    Eunjin Kwon; Jineun Kim; Gihaeng Kang; Tae Ho Kim

    2015-01-01

    In the title compound, C10H6Cl2N2 (systematic name: 4,6-dichloro-2-phenylpyrimidine), which is used commercially as the herbicide safener, fenclorim, the dihedral angle between the dichloropyrimidyl and phenyl rings is 9.45 (10)°. In the crystal, C—H...N hydrogen bonds link adjacent molecules, forming chains along the c-axis direction. In addition, weak intermolecular C—Cl...π [3.6185 (10) Å] and π–π [3.8796 (11) Å] interactions are present, forming a three-dimensional network....

  17. Crystal structure of fenclorim

    Directory of Open Access Journals (Sweden)

    Eunjin Kwon

    2015-10-01

    Full Text Available In the title compound, C10H6Cl2N2 (systematic name: 4,6-dichloro-2-phenylpyrimidine, which is used commercially as the herbicide safener, fenclorim, the dihedral angle between the dichloropyrimidyl and phenyl rings is 9.45 (10°. In the crystal, C—H...N hydrogen bonds link adjacent molecules, forming chains along the c-axis direction. In addition, weak intermolecular C—Cl...π [3.6185 (10 Å] and π–π [3.8796 (11 Å] interactions are present, forming a three-dimensional network.

  18. Crystal structure of metobromuron

    OpenAIRE

    Gihaeng Kang; Jineun Kim; Eunjin Kwon; Tae Ho Kim

    2015-01-01

    The title compound [systematic name: 3-(4-bromophenyl)-1-methoxy-1-methylurea], C9H11BrN2O2, is a phenylurea herbicide. The dihedral angle between the plane of the urea group and that of the bromophenyl ring is 39.13 (10)°. In the crystal, N—H...O and C—H...O hydrogen bonds and weak C—H...π interactions link adjacent molecules, forming chains along the a-axis direction. In addition, short intermolecular Br...Br contacts [3.648 (4) Å] are present, resulting in a two-dimensional network extendi...

  19. Crystal structure of azimsulfuron

    OpenAIRE

    Youngeun Jeon; Jineun Kim; Eunjin Kwon; Tae Ho Kim

    2015-01-01

    The title compound {systematic name: 1-(4,6-dimethoxypyrimidin-2-yl)-3-[1-methyl-4-(2-methyl-2H-tetrazol-5-yl)pyrazol-5-ylsulfonyl]urea}, C13H16N10O5S, is a sulfonylurea herbicide. In this compound, the dihedral angles between the planes of the central pyrazole and the terminal dimethoxypyrimidine and tetrazole rings are 79.10 (8) and 17.21 (16)°, respectively. In the crystal, N—H...O hydrogen bonds link adjacent molecules, forming R22(8) inversion dimers. In addition, weak C—H...O and C—H......

  20. Crystal structure of dimethomorph

    OpenAIRE

    Gihaeng Kang; Jineun Kim; Eunjin Kwon; Tae Ho Kim

    2015-01-01

    In the title compound, C21H22ClNO4 [systematic name: (E)-3-(4-chlorophenyl)-3-(3,4-dimethoxyphenyl)-1-(morpholin-4-yl)prop-2-en-1-one], which is the morpholine fungicide dimethomorph, the dihedral angles between the mean planes of the central chlorophenyl and the terminal benzene and morpholine (r.m.s. deviation = 0.2233 Å) rings are 71.74 (6) and 63.65 (7)°, respectively. In the crystal, molecules are linked via C—H...O hydrogen bonds and weak Cl...π interactions [3.8539 (11) Å], forming a t...

  1. Invisible defects in complex crystals

    International Nuclear Information System (INIS)

    We show that invisible localized defects, i.e. defects that cannot be detected by an outside observer, can be realized in a crystal with an engineered imaginary potential at the defect site. The invisible defects are synthesized by means of supersymmetric (Darboux) transformations of an ordinary crystal using band-edge wavefunctions to construct the superpotential. The complex crystal has an entire real-valued energy spectrum and Bragg scattering is not influenced by the defects. An example of complex crystal synthesis is presented for the Mathieu potential. -- Highlights: •We show the existence of invisible localized defects in complex crystals. •They turn out to be fully invisible to Bloch waves belonging to any lattice band. •An example of invisible defect is presented for a PT-symmetric Mathieu crystal

  2. Evaluation of CZT crystals from the former Soviet Union

    International Nuclear Information System (INIS)

    Vertical high pressure Bridgman (VHPB) Cd1-xZnxTe (0.04 241Am radioactive source was found. Electron lifetimes below 1 (micro)s were measured in crystals having significant numbers of micro-defects, compared to lifetimes of 5--15 (micro)s found in spectrometer grade materials produced in the US. Furthermore, the zinc composition along the growth axis showed better homogeneity in comparison with the US material

  3. Magnetic Field Applications in Semiconductor Crystal Growth and Metallurgy

    Science.gov (United States)

    Mazuruk, Konstantin; Ramachandran, Narayanan; Grugel, Richard; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    The Traveling Magnetic Field (TMF) technique, recently proposed to control meridional flow in electrically conducting melts, is reviewed. In particular, the natural convection damping capability of this technique has been numerically demonstrated with the implication of significantly improving crystal quality. Advantages of the traveling magnetic field, in comparison to the more mature rotating magnetic field method, are discussed. Finally, results of experiments with mixing metallic alloys in long ampoules using TMF is presented

  4. Lensing effects in a nematic liquid crystal with topological defects.

    Science.gov (United States)

    Sátiro, C; Moraes, F

    2006-06-01

    Light traveling through a liquid crystal with disclinations perceives a geometrical background which causes lensing effects similar to the ones predicted for cosmic objects like global monopoles and cosmic strings. In this paper we explore the effective geometry as perceived by light in such media. The comparison between both systems suggests that experiments can be done in the laboratory to simulate optical properties, like gravitational lensing, of cosmic objects. PMID:16775663

  5. Optical tornadoes in photonic crystals

    OpenAIRE

    Onoda, Masaru; Ochiai, Tetsuyuki

    2008-01-01

    Based on an optical analogy of spintronics, the generation of optical tornadoes is theoretically investigated in two-dimensional photonic crystals without space-inversion symmetry. We address its close relation to the Berry curvature in crystal momentum space, which represents the non-trivial geometric property of a Bloch state. It is shown that the Berry curvature is easily controlled by tuning two types of dielectric rods in a honeycomb photonic crystal. Then, Bloch states with large Berry ...

  6. Quasimetallic silicon micromachined photonic crystals

    International Nuclear Information System (INIS)

    We report on fabrication of a layer-by-layer photonic crystal using highly doped silicon wafers processed by semiconductor micromachining techniques. The crystals, built using (100) silicon wafers, resulted in an upper stop band edge at 100 GHz. The transmission and defect characteristics of these structures were found to be analogous to metallic photonic crystals. We also investigated the effect of doping concentration on the defect characteristics. The experimental results agree well with predictions of the transfer matrix method simulations

  7. Inorganic Crystal Structure Database (ICSD)

    Science.gov (United States)

    SRD 84 FIZ/NIST Inorganic Crystal Structure Database (ICSD) (PC database for purchase)   The Inorganic Crystal Structure Database (ICSD) is produced cooperatively by the Fachinformationszentrum Karlsruhe(FIZ) and the National Institute of Standards and Technology (NIST). The ICSD is a comprehensive collection of crystal structure data of inorganic compounds containing more than 140,000 entries and covering the literature from 1915 to the present.

  8. Crystallization modifiers in lipid systems.

    Science.gov (United States)

    Ribeiro, Ana Paula Badan; Masuchi, Monise Helen; Miyasaki, Eriksen Koji; Domingues, Maria Aliciane Fontenele; Stroppa, Valter Luís Zuliani; de Oliveira, Glazieli Marangoni; Kieckbusch, Theo Guenter

    2015-07-01

    Crystallization of fats is a determinant physical event affecting the structure and properties of fat-based products. The stability of these processed foods is regulated by changes in the physical state of fats and alterations in their crystallization behavior. Problems like polymorphic transitions, oil migration, fat bloom development, slow crystallization and formation of crystalline aggregates stand out. The change of the crystallization behavior of lipid systems has been a strategic issue for the processing of foods, aiming at taylor made products, reducing costs, improving quality, and increasing the applicability and stability of different industrial fats. In this connection, advances in understanding the complex mechanisms that govern fat crystallization led to the development of strategies in order to modulate the conventional processes of fat structuration, based on the use of crystallization modifiers. Different components have been evaluated, such as specific triacyglycerols, partial glycerides (monoacylglycerols and diacylglycerols), free fatty acids, phospholipids and emulsifiers. The knowledge and expertise on the influence of these specific additives or minor lipids on the crystallization behavior of fat systems represents a focus of current interest for the industrial processing of oils and fats. This article presents a comprehensive review on the use of crystallization modifiers in lipid systems, especially for palm oil, cocoa butter and general purpose fats, highlighting: i) the removal, addition or fractionation of minor lipids in fat bases; ii) the use of nucleating agents to modify the crystallization process; iii) control of crystallization in lipid bases by using emulsifiers. The addition of these components into lipid systems is discussed in relation to the phenomena of nucleation, crystal growth, morphology, thermal behavior and polymorphism, with the intention of providing the reader with a complete panorama of the associated mechanisms

  9. Graphene-based photonic crystal

    OpenAIRE

    Berman, Oleg L.; Boyko, Vladimir S.; Kezerashvili, Roman Ya.; Kolesnikov, Anton A.; Lozovik, Yurii E.

    2010-01-01

    A novel type of photonic crystal formed by embedding a periodic array of constituent stacks of alternating graphene and dielectric discs into a background dielectric medium is proposed. The photonic band structure and transmittance of such photonic crystal are calculated. The graphene-based photonic crystals can be used effectively as the frequency filters and waveguides for the far infrared region of electromagnetic spectrum. Due to substantial suppression of absorption of low-frequency radi...

  10. Cost comparisons

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    How much does the LHC cost? And how much does this represent in other currencies? Below we present a table showing some comparisons with the cost of other projects. Looking at the figures, you will see that the cost of the LHC can be likened to that of three skyscrapers, or two seasons of Formula 1 racing! One year's budget of a single large F1 team is comparable to the entire materials cost of the ATLAS or CMS experiments.   Please note that all the figures are rounded for ease of reading.    CHF € $   LHC 4.6 billions 3 billions  4 billions   Space Shuttle Endeavour (NASA) 1.9 billion 1.3 billion 1.7 billion   Hubble Space Telescope (cost at launch – NASA/...

  11. Optical measurement of Verdet constants of two electrooptic crystals and their applications to optical sensors

    Science.gov (United States)

    Li, Changsheng

    2013-12-01

    Verdet constants of beta-barium borate (BBO) and lead molybdate (PMO) crystals are measured experimentally by the method of comparison with a block of terbium-doped glass with a known Verdet constant. Experimental setups mainly include two prism polarizers, a solenoid and ac current supply, and signal processing circuits. The influences of light intensity fluctuation, applied magnetic field and signal processing circuits on measurement result of Verdet constant can be removed by using the method of comparison. For light wavelength of 635nm, the measured Verdet constants respectively are 5.80+/-0.06 rad/(T.m) for the BBO crystal and 54.6+/-1.1 rad/(T.m) for the PMO crystal. A novel optical current sensor based on electrooptic compensation is designed in principle using the BBO crystal.

  12. Crystallization of glycine with ultrasound

    DEFF Research Database (Denmark)

    Louhi-Kultanen, Marjatta; Karjalainen, Milja; Rantanen, Jukka;

    2006-01-01

    Sonocrystallization has proved to be an efficient tool to influence the external appearance and structure of a crystalline product obtained by various crystallization methods. The present work focuses on high intensity sonocrystallization of glycine by varying amplitude of ultrasound with an...... ultrasound frequency of 20kHz at two temperature ranges 40-50 and 20-30 degrees C in a jacketed 250-ml cooling crystallizer equipped with a stirrer. The polymorph composition of the obtained crystals was analyzed with a temperature variable X-ray powder diffractometer (XRPD). XRPD results showed that...... ultrasound power. This study also showed, the higher the ultrasound amplitude the smaller the crystals obtained....

  13. Active and driven hydrodynamic crystals.

    Science.gov (United States)

    Desreumaux, N; Florent, N; Lauga, E; Bartolo, D

    2012-08-01

    Motivated by the experimental ability to produce monodisperse particles in microfluidic devices, we study theoretically the hydrodynamic stability of driven and active crystals. We first recall the theoretical tools allowing to quantify the dynamics of elongated particles in a confined fluid. In this regime hydrodynamic interactions between particles arise from a superposition of potential dipolar singularities. We exploit this feature to derive the equations of motion for the particle positions and orientations. After showing that all five planar Bravais lattices are stationary solutions of the equations of motion, we consider separately the case where the particles are passively driven by an external force, and the situation where they are self-propelling. We first demonstrate that phonon modes propagate in driven crystals, which are always marginally stable. The spatial structures of the eigenmodes depend solely on the symmetries of the lattices, and on the orientation of the driving force. For active crystals, the stability of the particle positions and orientations depends not only on the symmetry of the crystals but also on the perturbation wavelengths and on the crystal density. Unlike unconfined fluids, the stability of active crystals is independent of the nature of the propulsion mechanism at the single-particle level. The square and rectangular lattices are found to be linearly unstable at short wavelengths provided the volume fraction of the crystals is high enough. Differently, hexagonal, oblique, and face-centered crystals are always unstable. Our work provides a theoretical basis for future experimental work on flowing microfluidic crystals. PMID:22864543

  14. Crystal engineering: A brief overview

    Indian Academy of Sciences (India)

    Gautam R Desiraju

    2010-09-01

    Crystal structures of organic and metal-organic compounds have been determined in enormous numbers over the past century, and at the time of writing this review, the Cambridge Structural Database has just crossed the half million mark. The possibility of designing a particular crystal packing is, however, of more recent origin and the subject of crystal engineering has addressed this possibility, more or less systematically, during the past 30 years. Crystal engineering demands a detailed and thorough knowledge of intermolecular interactions, which act as the supramolecular glue that binds molecules into crystals. It also requires systematic strategies for the design of a crystal, the architectural blueprint as it were. Finally, this enterprise needs to be geared towards a useful property in that the crystal that is being designed is a functional one. All these features of the subject are directly or indirectly connected with the fact that there is a very large database of known crystal structures that is available to the crystal engineer. This review attempts to briefly survey the current scenario in this expanding subject.

  15. Pendellosung effect in photonic crystals

    CERN Document Server

    Savo, S; Miletto, C; Andreone, A; Dardano, P; Moretti, L; Mocella, V

    2008-01-01

    At the exit surface of a photonic crystal, the intensity of the diffracted wave can be periodically modulated, showing a maximum in the "positive" (forward diffracted) or in the "negative" (diffracted) direction, depending on the slab thickness. This thickness dependence is a direct result of the so-called Pendellosung phenomenon, consisting of the periodic exchange inside the crystal of the energy between direct and diffracted beams. We report the experimental observation of this effect in the microwave region at about 14 GHz by irradiating 2D photonic crystal slabs of different thickness and detecting the intensity distribution of the electromagnetic field at the exit surface and inside the crystal itself.

  16. Understanding quartz crystals and oscillators

    CERN Document Server

    Cerda, Ramon M

    2014-01-01

    Quartz, unique in its chemical, electrical, mechanical, and thermal properties, is used as a frequency control element in applications where stability of frequency is an absolute necessity. Without crystal controlled transmission, radio and television would not be possible in their present form. The quartz crystals allow the individual channels in communication systems to be spaced closer together to make better use of one of most precious resources -- wireless bandwidth.This book describes the characteristics of the art of crystal oscillator design, including how to specify and select crystal

  17. Scintillation crystals required for PET

    International Nuclear Information System (INIS)

    In PET, inorganic scintillator crystals are used to record γ rays produced by the annihilation of positrons emitted by injected tracers. The ultimate performance of the camera is strongly tied to both the physical and scintillation properties of the crystals. For this reason, researchers have investigated virtually all known scintillator crystals for possible use in PET. Despite this massive research effort, only a few different scintillators have been found that have a suitable use. Two recently developed scintillator crystals (LSO and GSO), appears to surpass all previously used materials in most respects and promises to be the basis for the next generation of PET cameras. (authors)

  18. Modelling of crystallizer wear

    Directory of Open Access Journals (Sweden)

    J. David

    2012-12-01

    Full Text Available Purpose: In this paper will be described an analysis of control problems and technical lifetime modeling of continuous casting device crystallizers. A full exploitation of continuous casting equipment (CCE advantages can only be achieved through a control system that minimizes all undesirable effects on the technological process. Some of the undesirable effects influencing the CCE process effectiveness are the failures and service interruptions. The failures and service interruptions are caused by a number of factors, impacts and processes that effect and run directly on the equipment in its individual parts during its operation.Design/methodology/approach: This problem was solved by connection of dependability theory and artificial neural networks.Findings: A prediction of crystallizer’s desk’s wear model was created on the basis of artificial neural networks and analytics diagnostics.Research limitations/implications: The limitations are given by operational data quantity. These limitations are for learning process and model adaptability.Practical implications: These problems are solved with cooperation with regional metallurgical companies. Gained results will be applied into the operational conditions.Originality/value: Signification consists of dependability theory and artificial neural networks, when solving a prediction model of crystallizers wear.

  19. Photonic Crystal Optical Tweezers

    CERN Document Server

    Wilson, Benjamin K; Bachar, Stephanie; Knouf, Emily; Bendoraite, Ausra; Tewari, Muneesh; Pun, Suzie H; Lin, Lih Y

    2009-01-01

    Non-invasive optical manipulation of particles has emerged as a powerful and versatile tool for biological study and nanotechnology. In particular, trapping and rotation of cells, cell nuclei and sub-micron particles enables unique functionality for various applications such as tissue engineering, cancer research and nanofabrication. We propose and demonstrate a purely optical approach to rotate and align particles using the interaction of polarized light with photonic crystal nanostructures to generate enhanced trapping force. With a weakly focused laser beam we observed efficient trapping and transportation of polystyrene beads with sizes ranging from 10 um down to 190 nm as well as cancer cell nuclei. In addition, we demonstrated alignment of non-spherical particles using a 1-D photonic crystal structure. Bacterial cells were trapped, rotated and aligned with optical intensity as low as 17 uW/um^2. Finite-difference time domain (FDTD) simulations of the optical near-field and far-field above the photonic c...

  20. Crystal structure of triclopyr

    Directory of Open Access Journals (Sweden)

    Seonghwa Cho

    2014-09-01

    Full Text Available In the title compound {systematic name: 2-[(3,5,6-trichloropyridin-2-yloxy]acetic acid}, the herbicide triclopyr, C7H4Cl3NO3, the asymmetric unit comprises two independent molecules in which the dihedral angles between the mean plane of the carboxylic acid group and the pyridyl ring plane are 79.3 (6 and 83.8 (5°. In the crystal, pairs of intermolecular O—H...O hydrogen bonds form dimers through an R22(8 ring motif and are extended into chains along [100] by weak π–π interactions [ring centroid separations = 3.799 (4 and 3.810 (4 Å]. In addition, short intermolecular Cl...Cl contacts [3.458 (2 Å] connect the chains, yielding a two-dimensional architecture extending parallel to (020. The crystal studied was found to be non-merohedrally twinned with the minor component being 0.175 (4.

  1. Crystal structure of triclopyr.

    Science.gov (United States)

    Cho, Seonghwa; Kim, Jineun; Jeon, Youngeun; Kim, Tae Ho

    2014-09-01

    In the title compound {systematic name: 2-[(3,5,6-tri-chloro-pyridin-2-yl)-oxy]acetic acid}, the herbicide triclopyr, C7H4Cl3NO3, the asymmetric unit comprises two independent mol-ecules in which the dihedral angles between the mean plane of the carb-oxy-lic acid group and the pyridyl ring plane are 79.3 (6) and 83.8 (5)°. In the crystal, pairs of inter-molecular O-H⋯O hydrogen bonds form dimers through an R 2 (2)(8) ring motif and are extended into chains along [100] by weak π-π inter-actions [ring centroid separations = 3.799 (4) and 3.810 (4) Å]. In addition, short inter-molecular Cl⋯Cl contacts [3.458 (2) Å] connect the chains, yielding a two-dimensional architecture extending parallel to (020). The crystal studied was found to be non-merohedrally twinned with the minor component being 0.175 (4). PMID:25309266

  2. Tunable Topological Phononic Crystals

    KAUST Repository

    Chen, Ze-Guo

    2016-05-27

    Topological insulators first observed in electronic systems have inspired many analogues in photonic and phononic crystals in which remarkable one-way propagation edge states are supported by topologically nontrivial band gaps. Such band gaps can be achieved by breaking the time-reversal symmetry to lift the degeneracy associated with Dirac cones at the corners of the Brillouin zone. Here, we report on our construction of a phononic crystal exhibiting a Dirac-like cone in the Brillouin zone center. We demonstrate that simultaneously breaking the time-reversal symmetry and altering the geometric size of the unit cell result in a topological transition that we verify by the Chern number calculation and edge-mode analysis. We develop a complete model based on the tight binding to uncover the physical mechanisms of the topological transition. Both the model and numerical simulations show that the topology of the band gap is tunable by varying both the velocity field and the geometric size; such tunability may dramatically enrich the design and use of acoustic topological insulators.

  3. Preparation and thermal decomposition mechanism of Mg,Al-hydrotalcite nano-crystals with titania doping

    Institute of Scientific and Technical Information of China (English)

    REN Qing-li; LUO Qiang

    2006-01-01

    The highly pure nano-crystal Mg,Al-hydrotalcite with titania doping was synthesized by one-step liquid reaction method at atmospheric pressure. The preparation of the Mg,Al-hydrotalcite nano-crystal after doping titania was investigated according to the results of XRD,TEM,IR and DSC. Moreover,based on the DSC test results,the thermal mechanism functions of the Mg,Al-hydrotalcite with titania doping were studied after calculation and comparison.

  4. Micrometer-Thin Crystalline-Silicon Solar Cells Integrating Numerically Optimized 2-D Photonic Crystals

    OpenAIRE

    Depauw, V; Meng, X.; Daif, O. El; Gomard, G.; Lalouat, L; Drouard, E; Trompoukis, C.; Fave, A.; SEASSAL, C; Gordon, I.

    2013-01-01

    A 2-D photonic crystal was integrated experimentally into a thin-film crystalline-silicon solar cell of 1-{\\mu}m thickness, after numerical optimization maximizing light absorption in the active material. The photonic crystal boosted the short-circuit current of the cell, but it also damaged its open-circuit voltage and fill factor, which led to an overall decrease in performances. Comparisons between modeled and actual optical behaviors of the cell, and between ideal and actual morphologies,...

  5. Phase-matched third harmonic generation in ABN crystals at λ=1.064µm

    OpenAIRE

    Moog, L.; Block, D.

    1994-01-01

    A type II phase-matched third harmonic generation in an organic single crystal of 4-aminobenzonitrile has been studied. A Q-switched, mode-locked Nd-Yag laser at 1.064 µm has been used in the experiments. Direct comparison with a phase-matched type II THG from a BBO crystal shows that the UV signal in ABN is 50 times larger than in BBO.

  6. Crystallization and crystal manipulation of the Pterocarpus angolensis seed lectin.

    Science.gov (United States)

    Loris, Remy; Garcia-Pino, Abel; Buts, Lieven; Bouckaert, Julie; Beeckmans, Sonia; De Greve, Henri; Wyns, Lode

    2005-06-01

    The Man/Glc-specific legume lectin from the seeds of the African bloodwood tree (Pterocarpus angolensis) was crystallized in the presence of the disaccharide ligand Man(alpha1-3)ManMe. Small crystals initially appeared from a preliminary screen, but proved difficult to reproduce. The initial crystals were used to prepare microseeds, leading to a reproducible crystallization protocol. All attempts to obtain crystals directly of the ligand-free protein or of other carbohydrate complexes failed. However, the Man(alpha1-3)ManMe co-crystals withstand soaking with ten other carbohydrates known to bind to the lectin. Soaking for 15 min in 100 mM carbohydrate typically resulted in complete replacement of Man(alpha1-3)ManMe by the desired carbohydrate despite the involvement of lattice contacts at the binding site. Transferring the crystals for two weeks in carbohydrate-free artificial mother liquor resulted in the complete removal of the sugar from one of the two monomers in the asymmetric unit. Additional treatment of these crystals with 100 mM EDTA for two weeks resulted in removal of the structural calcium and manganese ions, which is accompanied by significant structural rearrangements of the loops that constitute the carbohydrate-binding site. PMID:15930620

  7. Engineering calcium oxalate crystal formation in Arabidopsis

    Science.gov (United States)

    Many plants accumulate crystals of calcium oxalate. Just how these crystals form remains unknown. To gain insight into the mechanisms regulating calcium oxalate crystal formation, a crystal engineering approach was initiated utilizing the non-crystal accumulating plant, Arabidopsis. The success of t...

  8. Evaluation of CZT crystals from the former Soviet Union

    CERN Document Server

    Hermon, H; James, R B; Antolak, A J; Morse, D H; Brunett, B A; Hackett, C; Tarver, E; Komar, V; Goorsky, M S; Yoon, H; Kolesnikov, N N; Toney, J; Schlesinger, T E

    1999-01-01

    Vertical high-pressure Bridgman (VHPB) Cd sub 1 sub - sub x Zn sub x Te (0.04crystals grown in the Ukraine and Russia have been evaluated and compared to US-grown materials. Various analytical techniques were used to study the materials for trace impurities, precipitates, crystallinity, and electrical transport properties. Relatively, high concentrations of carbon and trace impurities such as Se, Nd and Si have been detected in the crystals. In most cases, the crystals showed lower resistivity than US-grown CZT. However, recent crystals grown in Russia exhibited better detector performance than those grown previously, and a good response to an sup 2 sup 4 sup 1 Am radioactive source was found. Electron lifetimes below 1 mu s were measured in crystals having significant numbers of micro-defects, compared to lifetimes of 5-15 mu s found in spectrometer grade materials produced in the US. Furthermore, the zinc composition along the growth axis showed better homogeneity in comparison with ...

  9. Lattice location of gold in natural pyrite crystals

    International Nuclear Information System (INIS)

    The lattice location of gold atoms in naturally occurring Au-doped pyrite crystals has been investigated with a nuclear microprobe using ion channeling. The specimens consisted of 300-μm diameter pyrite crystals in veins embedded in a quartz matrix from the Emperor mine in Fiji. The specimens were prepared by standard geological specimen preparation techniques and the pyrite crystals were analysed in situ in the quartz matrix. Significant trace elements in the crystals, determined by Proton Induced X-ray Emission with a 3 MeV H+ microprobe, were Cu, As, Mo, Zn, Te, Au and Pb. The Au concentration was about 0.2 wt%. By the use of 2 MeV He+ ion channeling, the Miller indices of the lowest order crystal axes nearest to the normal were determined from backscattering yield maps from two-dimensional angular scanning and comparison of the resulting patterns with published gnomonic projections. Channeling angular yield curves were obtained from Fe, S, As and Au signals. The results indicate that at least 35% of the Au is substituted onto lattice sites

  10. Hydrogen Annealing Of Single-Crystal Superalloys

    Science.gov (United States)

    Smialek, James L.; Schaeffer, John C.; Murphy, Wendy

    1995-01-01

    Annealing at temperature equal to or greater than 2,200 degrees F in atmosphere of hydrogen found to increase ability of single-crystal superalloys to resist oxidation when subsequently exposed to oxidizing atmospheres at temperatures almost as high. Supperalloys in question are principal constituents of hot-stage airfoils (blades) in aircraft and ground-based turbine engines; also used in other high-temperature applications like chemical-processing plants, coal-gasification plants, petrochemical refineries, and boilers. Hydrogen anneal provides resistance to oxidation without decreasing fatigue strength and without need for coating or reactive sulfur-gettering constituents. In comparison with coating, hydrogen annealing costs less. Benefits extend to stainless steels, nickel/chromium, and nickel-base alloys, subject to same scale-adhesion and oxidation-resistance considerations, except that scale is chromia instead of alumina.

  11. Modification of Hydroxyapatite Crystal Using IR Laser

    CERN Document Server

    Satoh, Saburoh; Goto, M; Guan, W; Hayashi, N; Ihara, S; Yamabe, C; Yamaguchi, Y

    2004-01-01

    The first application of laser technology to dentistry was for the removal of caries. However, reports of laser application on improvement of dental surface were emerged, much attention has been focused on the laser’s potential to enhance enamel’s hardness and resistance to acid. Most of the previous reports concentrated on the photo issue interaction. Few research has pursued the photochemical phenomenon occurred during laser irradiation on biological tissues. In order to find a creative method to remineralize the dissociating enamel and exposed coronal of dentine, the authors developed a novel procedure during laser irradiation. Slice of sound molar and artificial HAp pellet were irradiated separately, with CO2 laser under different laser parameters. Tow series of samples covered with saturation calcium ion solution were irradiated separately. To investigate the crystal morphology, XRD pattern were surveyed. The comparison of each cases show that the chemical coating affected the ablation process evidentl...

  12. Crystal growth of an organic non-linear optical material from the vapour phase

    Energy Technology Data Exchange (ETDEWEB)

    Hou, W

    1999-07-01

    Due to the potential applications of organic non-linear optical materials in the areas of optical processing and communication, the investigation of the crystal growth of new organic NLO materials has been an active field for the last 20 years. For such uses it is necessary to produce single crystals of high quality and perfection, free of strain and defects. When crystals are grown from the solution and the melt, solvent and the decomposition component in the melt can introduce impurities and imperfection to the as-grown crystals. For crystals grown from vapour phase, in the absence of the solvent, this cannot occur and the method promises to yield single crystals of higher quality. Despite this attraction, little attention has been paid to the vapour phase growth of organic NLO crystals. It was with this in mind that the following investigation was carried out. Using Methyl p-hydroxybenzoate (p-MHB), a potential organic NLO material, a comparison investigation was made of its crystal growth from both the vapour phase and solution; this included an examination of morphological assessment, structural perfection, surface morphology and growth kinetics of the as-grown crystals and the mass transport properties in the growth ampoule. Collation of this data allows the definition of the best conditions for vapour phase growth to produce specimens of high quality and purity. (author)

  13. Crystal growth of an organic non-linear optical material from the vapour phase

    International Nuclear Information System (INIS)

    Due to the potential applications of organic non-linear optical materials in the areas of optical processing and communication, the investigation of the crystal growth of new organic NLO materials has been an active field for the last 20 years. For such uses it is necessary to produce single crystals of high quality and perfection, free of strain and defects. When crystals are grown from the solution and the melt, solvent and the decomposition component in the melt can introduce impurities and imperfection to the as-grown crystals. For crystals grown from vapour phase, in the absence of the solvent, this cannot occur and the method promises to yield single crystals of higher quality. Despite this attraction, little attention has been paid to the vapour phase growth of organic NLO crystals. It was with this in mind that the following investigation was carried out. Using Methyl p-hydroxybenzoate (p-MHB), a potential organic NLO material, a comparison investigation was made of its crystal growth from both the vapour phase and solution; this included an examination of morphological assessment, structural perfection, surface morphology and growth kinetics of the as-grown crystals and the mass transport properties in the growth ampoule. Collation of this data allows the definition of the best conditions for vapour phase growth to produce specimens of high quality and purity. (author)

  14. Secondary Crystallization of Isotactic Polystyrene

    NARCIS (Netherlands)

    LEMSTRA, PJ; SCHOUTEN, AJ; CHALLA, G

    1974-01-01

    When isotactic polystyrene (i-PS) is crystallized from the melt or from the glassy state at rather large supercooling an additional melting peak appears on the curve during scanning in a differential calorimeter. The overall rate of crystallization deduced from the total peak areas as a function of

  15. Dynamically controlled crystal growth system

    Science.gov (United States)

    Bray, Terry L. (Inventor); Kim, Larry J. (Inventor); Harrington, Michael (Inventor); DeLucas, Lawrence J. (Inventor)

    2002-01-01

    Crystal growth can be initiated and controlled by dynamically controlled vapor diffusion or temperature change. In one aspect, the present invention uses a precisely controlled vapor diffusion approach to monitor and control protein crystal growth. The system utilizes a humidity sensor and various interfaces under computer control to effect virtually any evaporation rate from a number of different growth solutions simultaneously by means of an evaporative gas flow. A static laser light scattering sensor can be used to detect aggregation events and trigger a change in the evaporation rate for a growth solution. A control/follower configuration can be used to actively monitor one chamber and accurately control replicate chambers relative to the control chamber. In a second aspect, the invention exploits the varying solubility of proteins versus temperature to control the growth of protein crystals. This system contains miniature thermoelectric devices under microcomputer control that change temperature as needed to grow crystals of a given protein. Complex temperature ramps are possible using this approach. A static laser light scattering probe also can be used in this system as a non-invasive probe for detection of aggregation events. The automated dynamic control system provides systematic and predictable responses with regard to crystal size. These systems can be used for microgravity crystallization projects, for example in a space shuttle, and for crystallization work under terrestial conditions. The present invention is particularly useful for macromolecular crystallization, e.g. for proteins, polypeptides, nucleic acids, viruses and virus particles.

  16. 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.

  17. Positioning Vise for Crystal Cleavage

    Science.gov (United States)

    Hallberg, F. C.; Morgan, C. J.

    1984-01-01

    Vise manipulates brittle crystals, such as lithium fluoride, so they are in proper position for cleaving. Vise allows crystals as thin as 2 millimeters or less positioned so that cleaved without breakage. Vise holds workpiece firmly but gently. Bushings, shafts and adjusting screw designed to move jaws smoothly and uniformly with great tactile sensitivity.

  18. Pharmaceutical crystallization with nanocellulose organogels.

    Science.gov (United States)

    Ruiz-Palomero, Celia; Kennedy, Stuart R; Soriano, M Laura; Jones, Christopher D; Valcárcel, Miguel; Steed, Jonathan W

    2016-06-14

    Carboxylated nanocellulose forms organogels at 0.3 wt% in the presence of a cationic surfactant. The resulting gels can be used as novel crystallization media for pharmaceutical solid form control, resulting in isolation a new sulfapyridine solvate, morphology modification and crystallization of an octadecylammonium salt of sulfamethoxazole. PMID:27168091

  19. Pharmaceutical crystallization with nanocellulose organogels.

    OpenAIRE

    Ruiz-Palomero, Celia; Kennedy, Stuart R.; Soriano, M. Laura; Jones, Christopher D.; Valcárcel, Miguel; Steed, Jonathan W

    2016-01-01

    Carboxylated nanocellulose forms organogels at 0.3 wt% in the presence of a cationic surfactant. The resulting gels can be used as novel crystallization media for pharmaceutical solid form control, resulting in isolation a new sulfapyridine solvate, morphology modification and crystallization of an octadecylammonium salt of sulfamethoxazole.

  20. Photonic-crystal fibers gyroscope

    Directory of Open Access Journals (Sweden)

    Ali Muse Haider

    2015-01-01

    Full Text Available In this paper we proposed to use of a photonic crystal fiber with an inner hollow defect. The use of such fibers is not affected by a material medium on the propagation of optical radiation. Photonic crystal fibers present special properties and capabilities that lead to an outstanding potential for sensing applications

  1. Acoustic Metamaterials and Phononic Crystals

    CERN Document Server

    2013-01-01

    This comprehensive book presents all aspects of acoustic metamaterials and phononic crystals. The emphasis is on acoustic wave propagation phenomena at interfaces such as refraction, especially unusual refractive properties and negative refraction. A thorough discussion of the mechanisms leading to such refractive phenomena includes local resonances in metamaterials and scattering in phononic crystals.

  2. 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.

  3. Voxelated liquid crystal elastomers

    Science.gov (United States)

    Ware, Taylor H.; McConney, Michael E.; Wie, Jeong Jae; Tondiglia, Vincent P.; White, Timothy J.

    2015-02-01

    Dynamic control of shape can bring multifunctionality to devices. Soft materials capable of programmable shape change require localized control of the magnitude and directionality of a mechanical response. We report the preparation of soft, ordered materials referred to as liquid crystal elastomers. The direction of molecular order, known as the director, is written within local volume elements (voxels) as small as 0.0005 cubic millimeters. Locally, the director controls the inherent mechanical response (55% strain) within the material. In monoliths with spatially patterned director, thermal or chemical stimuli transform flat sheets into three-dimensional objects through controlled bending and stretching. The programmable mechanical response of these materials could yield monolithic multifunctional devices or serve as reconfigurable substrates for flexible devices in aerospace, medicine, or consumer goods.

  4. Natural photonic crystals

    Science.gov (United States)

    Vigneron, Jean Pol; Simonis, Priscilla

    2012-10-01

    Photonic structures appeared in nature several hundred millions years ago. In the living world, color is used for communication and this important function strongly impacts the individual chances of survival as well as the chances to reproduce. This has a statistical influence on species populations. Therefore, because they are involved in evolution, natural color-generating structures are - from some point of view - highly optimized. In this short review, a survey is presented of the development of natural photonic crystal-type structures occurring in insects, spiders, birds, fishes and other marine animals, in plants and more, from the standpoint of light-waves propagation. One-, two-, and three-dimensional structures will be reviewed with selected examples.

  5. Natural photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Vigneron, Jean Pol, E-mail: jean-pol.vigneron@fundp.ac.be [Research Center in Physics of Matter and Radiation (PMR), University of Namur (FUNDP), rue de Bruxelles, 61, B-5000 Namur (Belgium); Simonis, Priscilla [Research Center in Physics of Matter and Radiation (PMR), University of Namur (FUNDP), rue de Bruxelles, 61, B-5000 Namur (Belgium)

    2012-10-15

    Photonic structures appeared in nature several hundred millions years ago. In the living world, color is used for communication and this important function strongly impacts the individual chances of survival as well as the chances to reproduce. This has a statistical influence on species populations. Therefore, because they are involved in evolution, natural color-generating structures are - from some point of view - highly optimized. In this short review, a survey is presented of the development of natural photonic crystal-type structures occurring in insects, spiders, birds, fishes and other marine animals, in plants and more, from the standpoint of light-waves propagation. One-, two-, and three-dimensional structures will be reviewed with selected examples.

  6. Natural photonic crystals

    International Nuclear Information System (INIS)

    Photonic structures appeared in nature several hundred millions years ago. In the living world, color is used for communication and this important function strongly impacts the individual chances of survival as well as the chances to reproduce. This has a statistical influence on species populations. Therefore, because they are involved in evolution, natural color-generating structures are - from some point of view - highly optimized. In this short review, a survey is presented of the development of natural photonic crystal-type structures occurring in insects, spiders, birds, fishes and other marine animals, in plants and more, from the standpoint of light-waves propagation. One-, two-, and three-dimensional structures will be reviewed with selected examples.

  7. Bioengineering single crystal growth.

    Science.gov (United States)

    Wu, Ching-Hsuan; Park, Alexander; Joester, Derk

    2011-02-16

    Biomineralization is a "bottom-up" synthesis process that results in the formation of inorganic/organic nanocomposites with unrivaled control over structure, superior mechanical properties, adaptive response, and the capability of self-repair. While de novo design of such highly optimized materials may still be out of reach, engineering of the biosynthetic machinery may offer an alternative route to design advanced materials. Herein, we present an approach using micro-contact-printed lectins for patterning sea urchin embryo primary mesenchyme cells (PMCs) in vitro. We demonstrate not only that PMCs cultured on these substrates show attachment to wheat germ agglutinin and concanavalin A patterns but, more importantly, that the deposition and elongation of calcite spicules occurs cooperatively by multiple cells and in alignment with the printed pattern. This allows us to control the placement and orientation of smooth, cylindrical calcite single crystals where the crystallographic c-direction is parallel to the cylinder axis and the underlying line pattern. PMID:21265521

  8. Crystal structure of triclopyr

    OpenAIRE

    Cho, Seonghwa; Kim, Jineun; Jeon, Youngeun; Kim, Tae Ho

    2014-01-01

    In the title compound {systematic name: 2-[(3,5,6-tri­chloro­pyridin-2-yl)­oxy]acetic acid}, the herbicide triclopyr, C7H4Cl3NO3, the asymmetric unit comprises two independent mol­ecules in which the dihedral angles between the mean plane of the carb­oxy­lic acid group and the pyridyl ring plane are 79.3 (6) and 83.8 (5)°. In the crystal, pairs of inter­molecular O—H⋯O hydrogen bonds form dimers through an R 2 2(8) ring motif and are extended into chains along [100] by weak π–π inter­actions ...

  9. Crystal structure of propaquizafop

    Directory of Open Access Journals (Sweden)

    Youngeun Jeon

    2014-12-01

    Full Text Available The title compound, C22H22ClN3O5 {systematic name: 2-(propan-2-ylideneaminooxyethyl (R-2-[4-(6-chloroquinoxalin-2-yloxyphenoxy]propionate}, is a herbicide. The asymmetric unit comprises two independent molecules in which the dihedral angles between the phenyl ring and the quinoxaline ring plane are 75.93 (7 and 82.77 (8°. The crystal structure features C—H...O, C—H...N, and C—H...Cl hydrogen bonds, as well as weak π–π interactions [ring-centroid separation = 3.782 (2 and 3.5952 (19 Å], resulting in a three-dimensional architecture.

  10. Diffraction. Single crystal, magnetic

    International Nuclear Information System (INIS)

    The analysis of crystal structure and magnetic ordering is usually based on diffraction phenomena caused by the interaction of matter with X-rays, neutrons, or electrons. Complementary information is achieved due to the different character of X-rays, neutrons and electrons, and hence their different interactions with matter and further practical aspects. X-ray diffraction using conventional laboratory equipment and/or synchrotron installations is the most important method for structure analyses. The purpose of this paper is to discuss special cases, for which, in addition to this indispensable part, neutrons are required to solve structural problems. Even though the huge intensity of modern synchrotron sources allows in principle the study of magnetic X-ray scattering the investigation of magnetic structures is still one of the most important applications of neutron diffraction. (K.A.)

  11. Crystal structure of flumioxazin

    OpenAIRE

    Hyunjin Park; Jineun Kim; Eunjin Kwon; Tae Ho Kim

    2015-01-01

    The title compound {systematic name: 2-[7-fluoro-3,4-dihydro-3-oxo-4-(prop-2-yn-1-yl)-2H-1,4-benzoxazin-6-yl]-4,5,6,7-tetrahydro-1H-isoindole-1,3(2H)-dione}, C19H15FN2O4, is a dicarboximide herbicide. The dihedral angle between the maleimide and benzene ring planes is 66.13 (5)°. In the crystal, C—H...O and C—H...F hydrogen bonds and weak C—H...π interactions [3.5601 (19) Å] link adjacent molecules, forming two-dimensional networks extending parallel to the (110) plane.

  12. Crystal structure of dimethomorph

    Directory of Open Access Journals (Sweden)

    Gihaeng Kang

    2015-09-01

    Full Text Available In the title compound, C21H22ClNO4 [systematic name: (E-3-(4-chlorophenyl-3-(3,4-dimethoxyphenyl-1-(morpholin-4-ylprop-2-en-1-one], which is the morpholine fungicide dimethomorph, the dihedral angles between the mean planes of the central chlorophenyl and the terminal benzene and morpholine (r.m.s. deviation = 0.2233 Å rings are 71.74 (6 and 63.65 (7°, respectively. In the crystal, molecules are linked via C—H...O hydrogen bonds and weak Cl...π interactions [3.8539 (11 Å], forming a three-dimensional structure.

  13. Crystal structure of pyrazoxyfen

    OpenAIRE

    Kwon, Eunjin; Kim, Jineun; Kang, Gihaeng; Kim, Tae Ho

    2015-01-01

    The title compound, C20H16Cl2N2O3 (systematic name: 2-{[4-(2,4-di­chloro­benzo­yl)-1,3-di­methyl­pyrazol-5-yl}­oxy}-1-phenyl­ethan-1-one), is the benzoyl­pyrazole herbicide pyrazoxyfen. The asymmetric unit comprises two independent mol­ecules, A and B, in which the pyrazole ring makes dihedral angles of 80.29 (10) and 61.70 (10)° and 87.60 (10) and 63.92 (8)°, respectively, with the di­chloro­phenyl and phenyl rings. In the crystal, C—H⋯O and C—H⋯N hydrogen bonds, and C—H⋯π and π–π [3.646 (2)...

  14. Crystal structure of flumioxazin

    Directory of Open Access Journals (Sweden)

    Hyunjin Park

    2015-10-01

    Full Text Available The title compound {systematic name: 2-[7-fluoro-3,4-dihydro-3-oxo-4-(prop-2-yn-1-yl-2H-1,4-benzoxazin-6-yl]-4,5,6,7-tetrahydro-1H-isoindole-1,3(2H-dione}, C19H15FN2O4, is a dicarboximide herbicide. The dihedral angle between the maleimide and benzene ring planes is 66.13 (5°. In the crystal, C—H...O and C—H...F hydrogen bonds and weak C—H...π interactions [3.5601 (19 Å] link adjacent molecules, forming two-dimensional networks extending parallel to the (110 plane.

  15. Crystal structure of fenclorim

    OpenAIRE

    Kwon, Eunjin; Kim, Jineun; Kang, Gihaeng; Kim, Tae Ho

    2015-01-01

    In the title compound, C10H6Cl2N2 (systematic name: 4,6-di­chloro-2-phenyl­pyrimidine), which is used commercially as the herbicide safener, fenclorim, the dihedral angle between the di­chloro­pyrimidyl and phenyl rings is 9.45 (10)°. In the crystal, C—H⋯N hydrogen bonds link adjacent mol­ecules, forming chains along the c-axis direction. In addition, weak inter­molecular C—Cl⋯π [3.6185 (10) Å] and π–π [3.8796 (11) Å] inter­actions are present, forming a three-dimensional network....

  16. Crystal structure of cyproconazole

    OpenAIRE

    Gihaeng Kang; Jineun Kim; Eunjin Kwon; Tae Ho Kim

    2015-01-01

    The title compound [systematic name: 2-(4-chlorophenyl)-3-cyclopropyl-1-(1H-1,2,4-triazol-1-yl)butan-2-ol], C15H18ClN3O, is a conazole fungicide. The asymmetric unit comprises two enantiomeric pairs (molecules A and B) in which the dihedral angles between the chlorophenyl and triazole rings are 46.54 (9) (molecule A) and 67.03 (8)° (molecule B). In the crystal, C—H...O, O—H...N and C—H...Cl hydrogen bonds and weak C—H...π interactions [3.473 (2) Å] link adjacent molecules, forming columns alo...

  17. Crystal structure of pencycuron

    Directory of Open Access Journals (Sweden)

    Gihaeng Kang

    2015-08-01

    Full Text Available In the title compound [systematic name: 1-(4-chlorobenzyl-1-cyclopentyl-3-phenylurea], C19H21ClN2O, which is a urea fungicide, the cyclopentyl ring adopts an envelope conformation, with one of the methylene C atoms adjacent to the C atom bonding to the N atom as the flap. The dihedral angles between the mean planes of the central cyclopentyl ring (all atoms and the chlorobenzyl and phenyl rings are 77.96 (6 and 57.77 (7°, respectively. In the crystal, N—H...O hydrogen bonds link adjacent molecules, forming C(4 chains propagating along the b-axis direction. The chains are linked by weak π–π interactions between the chlorobenzene rings [centroid–centroid separation = 3.9942 (9 Å], resulting in two-dimensional networks extending parellel to the (110 plane.

  18. Crystal structure of pyrazoxyfen

    OpenAIRE

    Eunjin Kwon; Jineun Kim; Gihaeng Kang; Tae Ho Kim

    2015-01-01

    The title compound, C20H16Cl2N2O3 (systematic name: 2-{[4-(2,4-dichlorobenzoyl)-1,3-dimethylpyrazol-5-yl}oxy}-1-phenylethan-1-one), is the benzoylpyrazole herbicide pyrazoxyfen. The asymmetric unit comprises two independent molecules, A and B, in which the pyrazole ring makes dihedral angles of 80.29 (10) and 61.70 (10)° and 87.60 (10) and 63.92 (8)°, respectively, with the dichlorophenyl and phenyl rings. In the crystal, C—H...O and C—H...N hydrogen bonds, and C—H...π and π–π [3.646 (2) Å] i...

  19. Crystal structure of metobromuron

    OpenAIRE

    Kang, Gihaeng; Kim, Jineun; Kwon, Eunjin; Kim, Tae Ho

    2015-01-01

    The title compound [systematic name: 3-(4-bromo­phen­yl)-1-meth­oxy-1-methyl­urea], C9H11BrN2O2, is a phenyl­urea herbicide. The dihedral angle between the plane of the urea group and that of the bromo­phenyl ring is 39.13 (10)°. In the crystal, N—H⋯O and C—H⋯O hydrogen bonds and weak C—H⋯π inter­actions link adjacent mol­ecules, forming chains along the a-axis direction. In addition, short inter­molecular Br⋯Br contacts [3.648 (4) Å] are present, resulting in a two-dimensional network extend...

  20. Crystal structure of cyproconazole

    OpenAIRE

    Kang, Gihaeng; Kim, Jineun; Kwon, Eunjin; Kim, Tae Ho

    2015-01-01

    The title compound [systematic name: 2-(4-chloro­phen­yl)-3-cyclo­propyl-1-(1H-1,2,4-triazol-1-yl)butan-2-ol], C15H18ClN3O, is a conazole fungicide. The asymmetric unit comprises two enanti­omeric pairs (mol­ecules A and B) in which the dihedral angles between the chloro­phenyl and triazole rings are 46.54 (9) (mol­ecule A) and 67.03 (8)° (mol­ecule B). In the crystal, C—H⋯O, O—H⋯N and C—H⋯Cl hydrogen bonds and weak C—H⋯π inter­actions [3.473 (2) Å] link adjacent mol­ecules, forming columns a...

  1. Crystal structure of pencycuron

    OpenAIRE

    Kang, Gihaeng; Kim, Jineun; Kwon, Eunjin; Kim, Tae Ho

    2015-01-01

    In the title compound [systematic name: 1-(4-chloro­benz­yl)-1-cyclo­pentyl-3-phenyl­urea], C19H21ClN2O, which is a urea fungicide, the cyclo­pentyl ring adopts an envelope conformation, with one of the methyl­ene C atoms adjacent to the C atom bonding to the N atom as the flap. The dihedral angles between the mean planes of the central cyclo­pentyl ring (all atoms) and the chloro­benzyl and phenyl rings are 77.96 (6) and 57.77 (7)°, respectively. In the crystal, N—H⋯O hydrogen bonds link adj...

  2. Crystal structure of metobromuron

    Directory of Open Access Journals (Sweden)

    Gihaeng Kang

    2015-08-01

    Full Text Available The title compound [systematic name: 3-(4-bromophenyl-1-methoxy-1-methylurea], C9H11BrN2O2, is a phenylurea herbicide. The dihedral angle between the plane of the urea group and that of the bromophenyl ring is 39.13 (10°. In the crystal, N—H...O and C—H...O hydrogen bonds and weak C—H...π interactions link adjacent molecules, forming chains along the a-axis direction. In addition, short intermolecular Br...Br contacts [3.648 (4 Å] are present, resulting in a two-dimensional network extending parallel to (101.

  3. Crystal structure of cyproconazole

    Directory of Open Access Journals (Sweden)

    Gihaeng Kang

    2015-12-01

    Full Text Available The title compound [systematic name: 2-(4-chlorophenyl-3-cyclopropyl-1-(1H-1,2,4-triazol-1-ylbutan-2-ol], C15H18ClN3O, is a conazole fungicide. The asymmetric unit comprises two enantiomeric pairs (molecules A and B in which the dihedral angles between the chlorophenyl and triazole rings are 46.54 (9 (molecule A and 67.03 (8° (molecule B. In the crystal, C—H...O, O—H...N and C—H...Cl hydrogen bonds and weak C—H...π interactions [3.473 (2 Å] link adjacent molecules, forming columns along the a axis.

  4. Crystal structure of flumioxazin

    OpenAIRE

    Park, Hyunjin; Kim, Jineun; Kwon, Eunjin; Kim, Tae Ho

    2015-01-01

    The title compound {systematic name: 2-[7-fluoro-3,4-di­hydro-3-oxo-4-(prop-2-yn-1-yl)-2H-1,4-benzoxazin-6-yl]-4,5,6,7-tetra­hydro-1H-iso­indole-1,3(2H)-dione}, C19H15FN2O4, is a dicarboximide herbicide. The dihedral angle between the male­imide and benzene ring planes is 66.13 (5)°. In the crystal, C—H⋯O and C—H⋯F hydrogen bonds and weak C—H⋯π inter­actions [3.5601 (19) Å] link adjacent mol­ecules, forming two-dimensional networks extending parallel to the (110) plane....

  5. Crystal structure of azimsulfuron

    OpenAIRE

    Jeon, Youngeun; Kim, Jineun; Kwon, Eunjin; Kim, Tae Ho

    2015-01-01

    The title compound {systematic name: 1-(4,6-di­meth­oxy­pyrimidin-2-yl)-3-[1-methyl-4-(2-methyl-2H-tetra­zol-5-yl)pyrazol-5-ylsulfon­yl]urea}, C13H16N10O5S, is a sulfonyl­urea herbicide. In this compound, the dihedral angles between the planes of the central pyrazole and the terminal di­meth­oxy­pyrimidine and tetra­zole rings are 79.10 (8) and 17.21 (16)°, respectively. In the crystal, N—H⋯O hydrogen bonds link adjacent mol­ecules, forming R 2 2(8) inversion dimers. In addition, weak C—H⋯O a...

  6. Crystal structure of azimsulfuron

    Directory of Open Access Journals (Sweden)

    Youngeun Jeon

    2015-07-01

    Full Text Available The title compound {systematic name: 1-(4,6-dimethoxypyrimidin-2-yl-3-[1-methyl-4-(2-methyl-2H-tetrazol-5-ylpyrazol-5-ylsulfonyl]urea}, C13H16N10O5S, is a sulfonylurea herbicide. In this compound, the dihedral angles between the planes of the central pyrazole and the terminal dimethoxypyrimidine and tetrazole rings are 79.10 (8 and 17.21 (16°, respectively. In the crystal, N—H...O hydrogen bonds link adjacent molecules, forming R22(8 inversion dimers. In addition, weak C—H...O and C—H...N hydrogen bonds and weak π–π interactions [ring centroid separation = 3.8255 (12 Å] are present, resulting in a three-dimensional architecture.

  7. Crystal structure of dimethomorph

    OpenAIRE

    Kang, Gihaeng; Kim, Jineun; Kwon, Eunjin; Kim, Tae Ho

    2015-01-01

    In the title compound, C21H22ClNO4 [systematic name: (E)-3-(4-chloro­phen­yl)-3-(3,4-di­meth­oxy­phen­yl)-1-(morpholin-4-yl)prop-2-en-1-one], which is the morpholine fungicide dimethomorph, the dihedral angles between the mean planes of the central chloro­phenyl and the terminal benzene and morpholine (r.m.s. deviation = 0.2233 Å) rings are 71.74 (6) and 63.65 (7)°, respectively. In the crystal, molecules are linked via C—H⋯O hydrogen bonds and weak Cl⋯π interactions [3.8539 (11) Å], forming ...

  8. Characterization of pure and copper-doped iron tartrate crystals grown in silica gel

    Indian Academy of Sciences (India)

    V Mathivanan; M Haris

    2013-07-01

    Single crystal growth of pure and copper-doped iron tartrate crystals bearing composition Cu Fe(1−) C4H4O6 · H2O, where = 0, 0.07, 0.06, 0.05, 0.04, 0.03, is achieved using gel technique. The elemental analysis has been done using energy-dispersive X-ray analysis (EDAX) spectrum. The characterization studies such as Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), magnetic analysis and thermal analysis have been done for crystals with = 0 for pure iron tartrate and with = 0.05 for copper-mixed iron tartrate crystals. A detailed comparison has been made between pure and doped crystals.

  9. Structure of crystallized layers by laser annealing of (100) and (111) self-implanted silicon samples

    International Nuclear Information System (INIS)

    Channeling effect techniques with a 2.0 MeV He+ Rutherford backscattering and transmission electron microscopy were used to characterize the crystallized layers after Q-switched ruby laser irradiation of 4,000 Angstroem thick amorphous layer on (100) and (111) underlined crystal substrates. At a laser energy density of 2.5 J/cm2 the crystal layer on the (111) specimen contains a large density of stacking-faults, that on (100) specimen contains a very small amount of screw dislocation lines. High quality single-crystal layers have been obtained after irradiation at 3.5 J/cm2. From a comparison with the growth rate and defect structure observed in thermally annealed implanted-amorphous layers, we propose that crystal growth by 50 ns pulse laser annealing occurs by melting the amorphous layer. (orig.)

  10. Crystallization behavior of Fe78Si13B9 metallic glass under high magnetic field

    Institute of Scientific and Technical Information of China (English)

    Yuanfei Yu; Baozhu Liu; Min Qi

    2008-01-01

    The effects of high magnetic field on the crystallization behavior of the Fe78Si13B9 metallic glass ribbon were studied. The samples were isothermal annealed for 30 min under high magnetic field and no field, respectively. Mierostructure transformation during crystallization was identified by X-ray diffraction and transmission electron microscopy. It was found that the crystallizations of Fe78Si13B9 metallic glass processed under different conditions were that the precipitation of dendrite α-Fe(Si) and spherulite (Fe,Si)3B phases forms amorphous matrix and then the metastable (Fe, Si)3B phase transforms into the stable Fe2B phase. The grain size of the crystals is smaller and more homogeneous for the isothermal annealed samples under high magnetic field in comparison with that under no field indicating that the crystallization behavior of Fe78Si13B9 metallic glass is suppressed by high magnetic field.

  11. CW frequency doubling of 1029 nm radiation Using single pass bulk and waveguide PPLN crystals

    CERN Document Server

    Chiodo, Nicola; Hrabina, Jan; Candela, Yves; Wallerand, Jean-Pierre; Acef, Ouali

    2013-01-01

    Following various works on second harmonic process using periodically poled Lithium Niobate crystals (PPLN), we report on the performances comparison between commercial bulk and waveguide crystals at 1029 nm. We use a continuous wave (CW) amplified Yb doped single fibre laser delivering up to 500mW in single mode regime. In case of bulk crystal we generate 4 mW using 400 mW IR power. The use of waveguide crystal leads to an increase of the harmonic power up to 33mW with input IR power limited to 200mW. Nevertheless, this impressive efficiency was affected by the long term degradation of the non-linear waveguide crystal.

  12. Crystal growth and luminescence properties of In[sub 6]WO[sub 12

    Energy Technology Data Exchange (ETDEWEB)

    Gaewdang, T.; Chaminade, J.P.; Garcia, A.; Fouassier, C.; Pouchard, M.; Hagenmuller, P. (Laboratoire de Chimie du Solide du CNRS, Univ. Bordeaux, Talence, (France)); Jacquier, B. (Laboratoire de Physico-Chimie des Materiaux Luminiscents, Univ. Lyon, Villeurbanne (France))

    1993-11-15

    Single crystals of indium tungstate In[sub 6]WO[sub 12] have been grown by chemical vapor deposition using TeCl[sub 4] as a transport agent. Isometric as well as octahedral-shaped transparent crystals are obtained with a size attaining 2 mm. The luminescence of both single crystals and powder samples has been investigated. On the basis of a comparison with Y[sub 6]WO[sub 12], the green emission is ascribed to charge transfer transitions within isolated octahedral tungstate groups

  13. General crystal in prebiotic context

    International Nuclear Information System (INIS)

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

  14. Growth habit of polar crystals

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Using coordination polyhedron rule, growth habit of polar crystals such as ZnO, ZnS and SiO2 is investigated. It shows that the growth rates in the positive and negative polar axis directions are different. The theoretical growth habit of ZnO crystal is hexagonal prism and the growth rates of its various faces are:V{0001}>V{0111}-->V{0110}->V{0111}->V{0001}-. The growth habit of ZnS crystal is tetrahedron and its growth rates of different crystal faces are: V{111}>V{001}>V{001} =V{100} =. The growth rate relationship between positive and negative polar axis directions of SiO2 crystal V[1120]-->V[1120]-.is These results are in agreement with the growth habits observed under hydrothermal conditions. The different growth rates between positive and negative polar axis directions cannot be explained by PBC theory.

  15. Computational strain gradient crystal plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2014-01-01

    A numerical method for viscous strain gradient crystal plasticity theory is presented, which incorporates both energetic and dissipative gradient effects. The underlying minimum principles are discussed as well as convergence properties of the proposed finite element procedure. Three problems...... of plane crystal plasticity are studied: pure shear of a single crystal between rigid platens as well as plastic deformation around cylindrical voids in hexagonal close packed and face centered cubic crystals. Effective in-plane constitutive slip parameters for plane strain deformation of specifically...... oriented face centered cubic crystals are developed in terms of the crystallographic slip parameters. The effect on geometrically necessary dislocation structures introduced by plastic deformation is investigated as a function of the ratio of void radius to plasticity length scale....

  16. 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...

  17. Photonic crystals in epitaxial semiconductors

    CERN Document Server

    La Rue, R M de

    1998-01-01

    The title of the paper uses the expression "photonic crystals". By photonic crystals, we mean regular periodic structures with a substantial refractive index variation in one-, two- or three- dimensional space. Such crystals can $9 exist naturally, for example natural opal, but are more typically fabricated by people. Under sufficiently strong conditions, i.e., sufficiently large refractive index modulation, correct size of structural components, and $9 appropriate rotational and translational symmetry, these crystals exhibit the characteristics of a photonic bandgap (PBG) structure. In a full photonic bandgap structure there is a spectral stop band for electromagnetic waves $9 propagating in any direction through the structure and with an arbitrary state of polarization. This behavior is of interest both from a fundamental viewpoint and from the point of view of novel applications in photonic devices. The $9 paper gives an outline review of work on photonic crystals carried out by the Optoelectronics Researc...

  18. Prediction of molecular crystal structures

    CERN Document Server

    Beyer, T

    2001-01-01

    The ab initio prediction of molecular crystal structures is a scientific challenge. Reliability of first-principle prediction calculations would show a fundamental understanding of crystallisation. Crystal structure prediction is also of considerable practical importance as different crystalline arrangements of the same molecule in the solid state (polymorphs)are likely to have different physical properties. A method of crystal structure prediction based on lattice energy minimisation has been developed in this work. The choice of the intermolecular potential and of the molecular model is crucial for the results of such studies and both of these criteria have been investigated. An empirical atom-atom repulsion-dispersion potential for carboxylic acids has been derived and applied in a crystal structure prediction study of formic, benzoic and the polymorphic system of tetrolic acid. As many experimental crystal structure determinations at different temperatures are available for the polymorphic system of parac...

  19. MyCrystals - a simple visual data management program for laboratory-scale crystallization experiments

    DEFF Research Database (Denmark)

    Løvgreen, Monika Nøhr; Løvgreen, Mikkel; Christensen, Hans Erik Mølager;

    2009-01-01

    MyCrystals is designed as a user-friendly program to display crystal images and list crystallization conditions. The crystallization conditions entry fields can be customized to suit the experiments. MyCrystals is also able to sort the images by the entered crystallization conditions, which...

  20. Growing single crystals in silica gel

    Science.gov (United States)

    Rubin, B.

    1970-01-01

    Two types of chemical reactions for crystal growing are discussed. The first is a metathetical reaction to produce calcium tartrate tetrahydrate crystals, the second is a decomplexation reaction to produce cuprous chloride crystals.

  1. Effects of impurities on crystal growth in fructose crystallization

    Science.gov (United States)

    Chu, Y. D.; Shiau, L. D.; Berglund, K. A.

    1989-10-01

    The influence of impurities on the crystallization of anhydrous fructose from aqueous solution was studied. The growth kinetics of fructose crystals in the fructose-water-glucose and fructose-water-difructose dianhydrides systems were investigated using photomicroscopic contact nucleation techniques. Glucose is the major impurity likely to be present in fructose syrup formed during corn wet milling, while several difructose dianhydrides are formed in situ under crystallization conditions and have been proposed as a cause in the decrease of overall yields. Both sets of impurities were found to cause inhibition of crystal growth, but the mechanisms responsible in each case are different. It was found that the presence of glucose increases the solubility of fructose in water and thus lowers the supersaturation of the solution. This is probably the main effect responsible for the decrease of crystal growth. Since the molecular structures of difructose dianhydrides are similar to that of fructose, they are probably "tailor-made" impurities. The decrease of crystal growth is probably caused by the incorporation of these impurities into or adsorption to the crystal surface which would accept fructose molecules in the orientation that existed in the difructose dianhydride.

  2. Effects of increasing size and changing europium activator concentration in KCaI3 scintillator crystals

    Science.gov (United States)

    Lindsey, Adam C.; Zhuravleva, Mariya; Wu, Yuntao; Stand, Luis; Loyd, Matthew; Gokhale, Sasmit; Koschan, Merry; Melcher, Charles L.

    2016-09-01

    KCaI3:Eu crystals have been identified as very promising for use in spectroscopic detector applications related to nuclear nonproliferation and domestic security efforts. Initial studies have shown for small crystals a few mm3 in size with 3% europium dopant concentration, a high light yield of >70,000 ph/MeV and energy resolution of ≈3% at 662 keV is attainable which is comparable with the highest performance scintillators discovered. In this work, single crystals of KCaI3 with a range of Eu2+ doping between 0 and 5 at% substituting for Ca2+ were grown at 22 mm diameter and their performance for gamma-ray spectroscopy studied. Comparisons among crystals approximately Ø22 mm×22 mm (8.4 cm3 or ≈0.5 in3) provide a more accurate understanding of how scintillation performance changes with Eu doping and increased crystal size. KCaI3 in the undoped form is shown to be a highly efficient intrinsic scintillator with a defect-related emission at 404 nm which coexists with the Eu2+ 5d-4f emission in low dopant concentrations and is completely re-absorbed in more heavily doped crystals. For larger crystals, effects from self-absorption due to Eu activation become more evident by a near doubling of decay time for 0.5 in3 crystals as the activator is increased from 0.5 to 5.0 at% Eu. Comparisons of pulse-height spectra obtained for Ø22 mm×22 mm cylinders with varying Eu concentration suggests best performance is achieved using lower Eu additions closer to 0.5-1.0 at%. Using a modified crystal packaging featuring an offset reflector geometry, 0.5 in3 crystals of KCaI3:Eu can attain under 4% energy resolution at 662 keV.

  3. Systematic replacement of lysine with glutamine and alanine in Escherichia coli malate synthase G: effect on crystallization

    International Nuclear Information System (INIS)

    Alanine and glutamine mutations were made to the same 15 lysine positions on the surface of E. coli malate synthase G and the impact on crystallization observed. The results support lysine replacement for improvement of crystallization and provide insight into site selection and type of amino-acid replacement. Two proposals recommend substitution of surface lysine residues as a means to improve the quality of protein crystals. In proposal I, substitution of lysine by alanine has been suggested to improve crystallization by reducing the entropic cost of ordering flexible side chains at crystal contacts. In proposal II, substitution of lysine by residues more commonly found in crystal contacts, such as glutamine, has been proposed to improve crystallization. 15 lysine residues on the surface of Escherichia coli malate synthase G, distributed over a variety of secondary structures, were individually mutated to both alanine and glutamine. For 28 variants, detailed studies of the effect on enzymatic activity and crystallization were conducted. This has permitted direct comparison of the relative effects of the two types of mutations. While none of the variants produced crystals suitable for X-ray structural determination, small crystals were obtained in a wide variety of conditions, in support of the general approach. Glutamine substitutions were found to be more effective than alanine in producing crystals, in support of proposal II. Secondary structure at the site of mutation does not appear to play a major role in determining the rate of success

  4. Predicting crystal structure and habit of organic micro-crystals by experimentally assisted molecular modelling (EAMM). The case of n-octylamino-NBD

    Science.gov (United States)

    Pèpe, Gérard; Fery-Forgues, Suzanne; Jouanna, Paul

    2011-10-01

    Experimentally Assisted Molecular Modelling (EAMM) is an original approach for predicting the structure of organic micro-crystals and deducing their habit in the presence of various solvents and additives. It is applied here in the case of n-octylamino-nitrobenzoxadiazole ( nOA-NBD), a fluorescent compound. This general approach is first of all described and validated by its blind application to three known and closely-related crystals. Then, the whole process is applied to predict the molecular crystal generated by n-octylamino-NBD, including the molecule conformation, its structure (cell parameters, molecular packing, X-ray powder diagrams) and its theoretical plus actual habits in the presence of a solvent ( p-xylene) and two additives (acetic acid and n-dodecane). The conformation of the predicted molecule is validated by comparison with two similar molecules embedded in observable crystals. Then, the choice between two proposed structures (with the same energy and two equiprobable packings) is based on the comparison between experimental and re-computed X-ray powder diffraction diagrams, and also on the interpretation of an actual TEM image in the light of the proposed cell parameters. This choice is confirmed by the comparison between the vapour-grown face development (proposed by the BFDH or the attachment energy models) and the actual face development in a pure solvent. Finally, the actual habit deduced from comparing the crystal attachment energy with the adsorption energy of solvent or additive molecules is validated by SEM images of NBD micro-crystals in presence of the solvent alone or in presence of both additives. In conclusion, the EAMM approach appears to be a decisive tool for quickly simulating structural and habit properties of the molecular crystals, accessible or not by experimentation. Thus, a numerical selection of molecules becomes possible in view of deriving organic materials with predetermined properties, such as the fluorescence

  5. Towards improved CZT crystals

    International Nuclear Information System (INIS)

    Past experimental efforts to improve CZT crystals for gamma spectrometer applications have been focused on reducing micron-scale defects such as tellurium inclusions and precipitates. While these micron-scale defects are important, experiments have shown that the micron-scale variations in transport can be caused by the formation and aggregation of atomic-scale defects such as dislocations and point defect clusters. Moreover, dislocation cells have been found to act as nucleation sites that cause the formation of large precipitates. To better solve the uniformity problem of CZT, atomic-scale defects must be understood and controlled. To this end, we have begun to develop an atomistic model that can be used to reveal the effects of small-scale defects and to guide experiments for reducing both atomic- and micron-scale (tellurium inclusions and precipitates) defects. Our model will be based upon a bond order potential (BOP) to enable large-scale molecular dynamics simulations of material structures at a high-fidelity level that was not possible with alternative methods. To establish how BOP improves over existing approaches, we report here our recent work on the assessment of two representative literature CdTe interatomic potentials that are currently widely used: the Stillinger-Weber (SW) potential and the Tersoff-Rockett (TR) potential. Careful examinations of phases, defects, and surfaces of the CdTe system were performed. We began our study by using both potentials to evaluate the lattice constants and cohesive energies of various Cd, Te, and CdTe phases including dimer, trimer, chain, square, rhomboid, tetrahedron, diamond-cubic (dc), simple-cubic (sc), body-centered-cubic (bcc), face-centered cubic (fcc), hexagonal-close-packed (hcp), graphite-sheet, A8, zinc-blende (zb), wurtzite (wz), NaCl, CsCl, etc. We then compared the results with our calculations using the density functional theory (DFT) quantum mechanical method. We also evaluated the suitability of the

  6. Magnetic dipole interactions in crystals

    Science.gov (United States)

    Johnston, David C.

    2016-01-01

    The influence of magnetic dipole interactions (MDIs) on the magnetic properties of local-moment Heisenberg spin systems is investigated. A general formulation is presented for calculating the eigenvalues λ and eigenvectors μ ̂ of the MDI tensor of the magnetic dipoles in a line (one dimension, 1D), within a circle (2D) or a sphere (3D) of radius r surrounding a given moment μ⃗i for given magnetic propagation vectors k for collinear and coplanar noncollinear magnetic structures on both Bravais and non-Bravais spin lattices. Results are calculated for collinear ordering on 1D chains, 2D square and simple-hexagonal (triangular) Bravais lattices, 2D honeycomb and kagomé non-Bravais lattices, and 3D cubic Bravais lattices. The λ and μ ̂ values are compared with previously reported results. Calculations for collinear ordering on 3D simple tetragonal, body-centered tetragonal, and stacked triangular and honeycomb lattices are presented for c /a ratios from 0.5 to 3 in both graphical and tabular form to facilitate comparison of experimentally determined easy axes of ordering on these Bravais lattices with the predictions for MDIs. Comparisons with the easy axes measured for several illustrative collinear antiferromagnets (AFMs) are given. The calculations are extended to the cycloidal noncollinear 120∘ AFM ordering on the triangular lattice where λ is found to be the same as for collinear AFM ordering with the same k. The angular orientation of the ordered moments in the noncollinear coplanar AFM structure of GdB4 with a distorted stacked 3D Shastry-Sutherland spin-lattice geometry is calculated and found to be in disagreement with experimental observations, indicating the presence of another source of anisotropy. Similar calculations for the undistorted 2D and stacked 3D Shastry-Sutherland lattices are reported. The thermodynamics of dipolar magnets are calculated using the Weiss molecular field theory for quantum spins, including the magnetic transition

  7. Crystal structure of human GDF11.

    Science.gov (United States)

    Padyana, Anil K; Vaidialingam, Bhamini; Hayes, David B; Gupta, Priyanka; Franti, Michael; Farrow, Neil A

    2016-03-01

    Members of the TGF-β family of proteins are believed to play critical roles in cellular signaling processes such as those involved in muscle differentiation. The extent to which individual family members have been characterized and linked to biological function varies greatly. The role of myostatin, also known as growth differentiation factor 8 (GDF8), as an inhibitor of muscle differentiation is well understood through genetic linkages. In contrast, the role of growth differentiation factor 11 (GDF11) is much less well understood. In humans, the mature forms of GDF11 and myostatin are over 94% identical. In order to understand the role that the small differences in sequence may play in the differential signaling of these molecules, the crystal structure of GDF11 was determined to a resolution of 1.50 Å. A comparison of the GDF11 structure with those of other family members reveals that the canonical TGF-β domain fold is conserved. A detailed structural comparison of GDF11 and myostatin shows that several of the differences between these proteins are likely to be localized at interfaces that are critical for the interaction with downstream receptors and inhibitors. PMID:26919518

  8. Multicolor photonic crystal laser array

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Jeremy B; Brener, Igal; Subramania, Ganapathi S; Wang, George T; Li, Qiming

    2015-04-28

    A multicolor photonic crystal laser array comprises pixels of monolithically grown gain sections each with a different emission center wavelength. As an example, two-dimensional surface-emitting photonic crystal lasers comprising broad gain-bandwidth III-nitride multiple quantum well axial heterostructures were fabricated using a novel top-down nanowire fabrication method. Single-mode lasing was obtained in the blue-violet spectral region with 60 nm of tuning (or 16% of the nominal center wavelength) that was determined purely by the photonic crystal geometry. This approach can be extended to cover the entire visible spectrum.

  9. Configurable silicon photonic crystal waveguides

    International Nuclear Information System (INIS)

    In this Letter, we demonstrate that the mode cut off of a photonic crystal waveguide can be trimmed with high accuracy by electron beam bleaching of a chromophore doped polymer cladding. Using this method, configurable waveguides are realized, which allow for spatially resolved changes of the photonic crystal's effective lattice constant as small as 7.6 pm. We show three different examples how to take advantage of configurable photonic crystal waveguides: Shifting of the complete transmission spectrum, definition of cavities with high quality factor, and tuning of existing cavities

  10. Crystal plasticity study of single crystal tungsten by indentation tests

    International Nuclear Information System (INIS)

    Owing to its favorable material properties, tungsten (W) has been studied as a plasma-facing material in fusion reactors. Experiments on W heating in plasma sources and electron beam facilities have shown an intense micro-crack formation at the heated surface and sub-surface. The cracks go deep inside the irradiated sample, and often large distorted areas caused by local plastic deformation are present around the cracks. To interpret the crack-induced microscopic damage evolution process in W, one needs firstly to understand its plasticity on a single grain level, which is referred to as crystal plasticity. In this thesis, the crystal plasticity of single crystal tungsten (SCW) has been studied by spherical and Berkovich indentation tests and the finite element method with a crystal plasticity model. Appropriate values of the material parameters included in the crystal plasticity model are determined by fitting measured load-displacement curves and pile-up profiles with simulated counterparts for spherical indentation. The numerical simulations reveal excellent agreement with experiment. While the load-displacement curves and the deduced indentation hardness exhibit little sensitivity to the indented plane at small indentation depths, the orientation of slip directions within the crystals governs the development of deformation hillocks at the surface. It is found that several factors like friction, indentation depth, active slip systems, misoriented crystal orientation, misoriented sample surface and azimuthal orientation of the indenter can affect the indentation behavior of SCW. The Berkovich indentation test was also used to study the crystal plasticity of SCW after deuterium irradiation. The critical load (pop-in load) for triggering plastic deformation under the indenter is found to depend on the crystallographic orientation. The pop-in loads decrease dramatically after deuterium plasma irradiation for all three investigated crystallographic planes.

  11. Crystal structure of pymetrozine

    Directory of Open Access Journals (Sweden)

    Youngeun Jeon

    2015-07-01

    Full Text Available The title compound, C10H11N5O {systematic name: 6-methyl-4-[(E-(pyridin-3-ylmethylideneamino]-4,5-dihydro-1,2,4-triazin-3(2H-one}, C10H11N5O, is used as an antifeedant in pest control. The asymmetric unit comprises two independent molecules, A and B, in which the dihedral angles between the pyridinyl and triazinyl ring planes [r.m.s. deviations = 0.0132 and 0.0255 ] are 11.60 (6 and 18.06 (4°, respectively. In the crystal, N—H...O, N—H...N, C—H...N and C—H...O hydrogen bonds, together with weak π–π interactions [ring-centroid separations = 3.5456 (9 and 3.9142 (9 Å], link the pyridinyl and triazinyl rings of A molecules, generating a three-dimensional network.

  12. Crystal structure of cyclosulfamuron

    Directory of Open Access Journals (Sweden)

    Gihaeng Kang

    2015-08-01

    Full Text Available The title compound (systematic name: 1-{[2-(cyclopropylcarbonylanilino]sulfonyl}-3-(4,6-dimethoxypyrimidin-2-ylurea, C17H19N5O6S, is a pyrimidinylsulfonylurea herbicide. The dihedral angles between the mean planes of the central benzene ring and the cyclopropyl and pyrimidinyl rings are 75.32 (9 and 88.79 (4°, respectively. The C atoms of the methoxy groups lie almost in the plane of the pyrimidine ring [deviations = 0.043 (2 and 0.028 (2 Å] and intramolecular N—H...N, N—H...O and C—H...O hydrogen bonds all close S(6 rings. In the crystal, N—H...O and C—H...O hydrogen bonds and weak π–π interactions [centroid–centroid distances = 3.6175 (9 and 3.7068 (9 Å] link adjacent molecules, forming a three-dimensional network.

  13. Crystal structure of pyrazoxyfen

    Directory of Open Access Journals (Sweden)

    Eunjin Kwon

    2015-12-01

    Full Text Available The title compound, C20H16Cl2N2O3 (systematic name: 2-{[4-(2,4-dichlorobenzoyl-1,3-dimethylpyrazol-5-yl}oxy}-1-phenylethan-1-one, is the benzoylpyrazole herbicide pyrazoxyfen. The asymmetric unit comprises two independent molecules, A and B, in which the pyrazole ring makes dihedral angles of 80.29 (10 and 61.70 (10° and 87.60 (10 and 63.92 (8°, respectively, with the dichlorophenyl and phenyl rings. In the crystal, C—H...O and C—H...N hydrogen bonds, and C—H...π and π–π [3.646 (2 Å] interactions link adjacent molecules, forming a two-dimensional network parellel to (011. In addition, the networks are linked by weak intermolecular C—Cl...π [3.356 (2, 3.950 (2, 3.250 (2 and 3.575 (2 Å] interactions, resulting in a three-dimensional architecture.

  14. A new era of crystallization: advances in polysilicon crystallization and crystal engineering

    International Nuclear Information System (INIS)

    High-quality poly-Si microstructure is needed for the fabrication of high-quality poly-Si TFTs. The crystallization process is a very critical step of the thin film transistor (TFT) fabrication process, as it needs to satisfy conflicting requirements on material quality and cost and, at the same time, comply with the thermal-budget constraints imposed by the display substrate. Historically, solid-phase-crystallization (SPC) was the first technology to produce poly-Si films for display applications, followed by the development of laser-annealing crystallization (LAC). Both of the technologies evolved significantly over the past 20 years with a variety of spin-offs that aimed at improving different features of the poly-Si crystallization process and/or the poly-Si microstructure. This paper discusses the motivation behind the evolution process in the crystallization technology. We discuss in detail the different aspects of various crystallization techniques and provide the rationale behind our belief that lateral-crystallization technology possesses the best collection of features to enable the formation of very high-quality poly-Si films compatible with the fabrication of state-of-the-art, ultra-high performance poly-Si TFT devices

  15. Heat transport through ion crystals

    Science.gov (United States)

    Freitas, Nahuel; Martinez, Esteban A.; Paz, Juan Pablo

    2016-01-01

    We study the thermodynamical properties of crystals of trapped ions which are laser cooled to two different temperatures in two separate regions. We show that these properties strongly depend on the structure of the ion crystal. Such structure can be changed by varying the trap parameters and undergoes a series of phase transitions from linear to zig-zag or helicoidal configurations. Thus, we show that these systems are ideal candidates to observe and control the transition from anomalous to normal heat transport. All structures behave as ‘heat superconductors’, with a thermal conductivity increasing linearly with system size and a vanishing thermal gradient inside the system. However, zig-zag and helicoidal crystals turn out to be hyper sensitive to disorder having a linear temperature profile and a length independent conductivity. Interestingly, disordered 2D ion crystals are heat insulators. Sensitivity to disorder is much smaller in the 1D case.

  16. Plasma model of superconducting crystals

    Science.gov (United States)

    Netesova, Nadezhda P.

    2016-04-01

    Within inharmonious plasma oscillation model the superconducting crystal AB is considered consisting of two subsystems 2AB=A2+B2. In high-temperature superconductors spontaneous division into two phases: superconducting and isolating was revealed. Phase separation was caused by plasma instability. It is obtained the transition superconducting phase temperature dependence Tc = F (q12, q1, q2, V12, V1, V2) on the isotopic substitution physical parameters: q - initial and component interaction parameters, V - volume in initial and component crystal lattices. The isotopic transition superconducting phase temperature displacement ΔTc is associated with the change of the initial and component interaction and crystal lattice parameters. From the plasma mechanism of superconductivity follows superconducting crystals exist at room temperature.

  17. Growth Defects in Biomacromolecular Crystals

    Science.gov (United States)

    2003-01-01

    NASA's ground based program confirmed close similarity between protein and small molecules crystal growth, but also revealed essential differences. No understanding exists as to why and when crystals grown in space are, in approx. 20 percent of cases, of higher quality. More rationale is needed in flight experiments. Ferritin crystals grown in space are 2.5 times cleaner than their terrestrial counterparts. This may occur because of the existence of a zone depleted with respect to impurities around a crystal growing in stagnant solution. This zone should appear since the distribution coefficient for homologous impurities exceeds unity. This impurity depletion zone hypothesis requires verification and development. Thorough purification from homologous impurities brought about resolution improvement from 2.6 to 1.8 angstroms for ferritin and from 2.6 to 2.0 angstroms for canavalin.

  18. Resonant phenomena in colloidal crystals

    OpenAIRE

    Palberg, Thomas; Würth, Mathias; König, Peter; Simnacher, Erwin; Leiderer, Paul

    1992-01-01

    Colloidal crystals of completely deionized suspensions of latex speres are subjected to oscillatory and steady shear, as well as to homogeneous and inhomogeneous electric fields. Various resonant phenomena observed in such experiments are reported.

  19. Crystal growth of an organic non-linear optical material from the vapour phase

    CERN Document Server

    Hou, W

    1999-01-01

    Due to the potential applications of organic non-linear optical materials in the areas of optical processing and communication, the investigation of the crystal growth of new organic NLO materials has been an active field for the last 20 years. For such uses it is necessary to produce single crystals of high quality and perfection, free of strain and defects. When crystals are grown from the solution and the melt, solvent and the decomposition component in the melt can introduce impurities and imperfection to the as-grown crystals. For crystals grown from vapour phase, in the absence of the solvent, this cannot occur and the method promises to yield single crystals of higher quality. Despite this attraction, little attention has been paid to the vapour phase growth of organic NLO crystals. It was with this in mind that the following investigation was carried out. Using Methyl p-hydroxybenzoate (p-MHB), a potential organic NLO material, a comparison investigation was made of its crystal growth from both the va...

  20. Large size CdWO4 crystal for energetic x- and γ-ray detection

    International Nuclear Information System (INIS)

    A Large size of Φ70 mm x 71 mm (2.1 kg) CdWO4 crystal with excellent quality was studied for the energy response of the crystal to the γ-rays. The large crystal was coupled with a green-extended Photomultiplier tube (PMT) and tested at room temperature. We measured light yield and energy resolution of the crystal using various radioactive sources. The energy resolutions of the CdWO4 crystal were obtained to be 9.5% and 5.3% for 662 keV and 2614 keV, respectively. Linearity of the crystal in different γ-ray energy was also measured. In the environmental background spectrum, well defined peaks of 1461 keV by 40K decay and 2614 keV by 208Tl decay were identified. A simulation study with GEANT4 package was performed for the efficiency comparison with commonly used NaI(Tl) crystal scintillators. The study showed that the CdWo4 crystal is the promising candidate for the boarder control and energetic X- and γ-ray detection equipment. (author)

  1. The biaxial nonlinear crystal BiB3O6 as a polarization entangled photon source using non-collinear type-II parametric down-conversion

    OpenAIRE

    Halevy, A.; Megidish, E.; Dovrat, L.; Eisenberg, H. S.; De Becker, P; Bohatý, L.

    2011-01-01

    We describe the full characterization of the biaxial nonlinear crystal BiB3O6 (BiBO) as a polarization entangled photon source using non-collinear type-II parametric down-conversion. We consider the relevant parameters for crystal design, such as cutting angles, polarization of the photons, effective nonlinearity, spatial and temporal walk-offs, crystal thickness and the effect of the pump laser bandwidth. Experimental results showing entanglement generation with high rates and a comparison t...

  2. Chiral Crystal Growth under Grinding

    OpenAIRE

    Saito, Yukio; Hyuga, Hiroyuki

    2008-01-01

    To study the establishment of homochirality observed in the crystal growth experiment of chiral molecules from a solution under grinding, we extend the lattice gas model of crystal growth as follows. A lattice site can be occupied by a chiral molecule in R or S form, or can be empty. Molecules form homoclusters by nearest neighbor bonds. They change their chirality if they are isolated monomers in the solution. Grinding is incorporated by cutting and shafling the system randomly. It is shown ...

  3. Future ISIS single crystal instruments

    International Nuclear Information System (INIS)

    The designs of two proposed new single crystal instruments for ISIS are described. The biological structures instrument DIBS will allow the study of large unit cell materials in reasonable counting times. HRED, the high resolution elastic diffractometer, will provide a single crystal instrument of resolution ΔQ/Q ∼ 10-3, increasing the available resolution for reciprocal space surveying by some 10-fold over that currently obtainable on SXD. (author)

  4. Crystal Growth Inside an Octant

    OpenAIRE

    Olejarz, Jason; Krapivsky, P. L.

    2013-01-01

    We study crystal growth inside an infinite octant on a cubic lattice. The growth proceeds through the deposition of elementary cubes into inner corners. After re-scaling by the characteristic size, the interface becomes progressively more deterministic in the long-time limit. Utilizing known results for the crystal growth inside a two-dimensional corner, we propose a hyperbolic partial differential equation for the evolution of the limiting shape. This equation is interpreted as a Hamilton-Ja...

  5. Polariton effects in naphthalene crystals

    Energy Technology Data Exchange (ETDEWEB)

    Robinette, S. L.

    1977-10-01

    The experimental verification of the two-step nature of energy dissipation of photon energy by a crystal is the subject of this dissertation. The ..cap alpha..(O,O) Davydov component of the lowest energy singlet transition in pure strain-free napthalene single crystals is shown to exhibit an increase in absorption with increasing temperature, due to an increase in polariton damping via polariton-phonon scattering processes. (GHT)

  6. Charge transport in organic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ortmann, Frank

    2009-07-01

    The understanding of charge transport is one of the central goals in the research on semiconducting crystals. For organic crystals this is particularly complicated due to the strength of the electron-phonon interaction which requires the description of a seamless transition between the limiting cases of a coherent band-transport mechanism and incoherent hopping. In this thesis, charge transport phenomena in organic crystals are studied by theoretical means. A theory for charge transport in organic crystals is developed which covers the whole temperature range from low T, where it reproduces an expression from the Boltzmann equation for band transport, via elevated T, where it generalizes Holstein's small-polaron theory to finite bandwidths, up to high T, for which a temperature dependence equal to Marcus' electron-transfer theory is obtained. Thereby, coherent band transport and thermally induced hopping are treated on equal footing while simultaneously treating the electron-phonon interaction non-perturbatively. By avoiding the approximation of narrow polaron bands the theory allows for the description of large and small polarons and serves as a starting point for computational studies. The theoretical description is completed by using ab initio material parameters for the selected crystals under study. These material parameters are taken from density functional theory calculations for durene, naphthalene, and guanine crystals. Besides the analysis of the transport mechanism, special focus is put on the study of the relationship between mobility anisotropy and structure of the crystals. This study is supported by a 3D-visualization method for the transport channels in such crystals which has been derived in this thesis. (orig.)

  7. Modeling of photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Barkou, Stig Eigil

    1999-01-01

    Diferent theoretical models for analysis of photonic crystal fibres are reviewed and compaired. The methods span from simple scalar approaches to full-vectorial models using different mode-field decompositions. The specific advantages of the methods are evaluated.......Diferent theoretical models for analysis of photonic crystal fibres are reviewed and compaired. The methods span from simple scalar approaches to full-vectorial models using different mode-field decompositions. The specific advantages of the methods are evaluated....

  8. Phononic crystals and acoustic metamaterials

    OpenAIRE

    Ming-Hui Lu; Liang Feng; Yan-Feng Chen

    2009-01-01

    Phononic crystals have been proposed about two decades ago and some important characteristics such as acoustic band structure and negative refraction have stimulated fundamental and practical studies in acoustic materials and devices since then. To carefully engineer a phononic crystal in an acoustic “atom” scale, acoustic metamaterials with their inherent deep subwavelength nature have triggered more exciting investigations on negative bulk modulus and/or negative mass density. Acoustic surf...

  9. Adaptive Liquid Crystal Windows

    Energy Technology Data Exchange (ETDEWEB)

    Taheri, Bahman; Bodnar, Volodymyr

    2011-12-31

    Energy consumption by private and commercial sectors in the U.S. has steadily grown over the last decade. The uncertainty in future availability of imported oil, on which the energy consumption relies strongly, resulted in a dramatic increase in the cost of energy. About 20% of this consumption are used to heat and cool houses and commercial buildings. To reduce dependence on the foreign oil and cut down emission of greenhouse gases, it is necessary to eliminate losses and reduce total energy consumption by buildings. To achieve this goal it is necessary to redefine the role of the conventional windows. At a minimum, windows should stop being a source for energy loss. Ideally, windows should become a source of energy, providing net gain to reduce energy used to heat and cool homes. It is possible to have a net energy gain from a window if its light transmission can be dynamically altered, ideally electronically without the need of operator assistance, providing optimal control of the solar gain that varies with season and climate in the U.S. In addition, the window must not require power from the building for operation. Resolution of this problem is a societal challenge and of national interest and will have a broad global impact. For this purpose, the year-round, allclimate window solution to provide an electronically variable solar heat gain coefficient (SHGC) with a wide dynamic range is needed. AlphaMicron, Inc. (AMI) developed and manufactured 1ft × 1ft prototype panels for the world’s first auto-adjusting Adaptive Liquid Crystal Windows (ALCWs) that can operate from sunlight without the need for external power source and demonstrate an electronically adjustable SHGC. This novel windows are based on AlphaMicron’s patented e-Tint® technology, a guesthost liquid crystal system implemented on flexible, optically clear plastic films. This technology is suitable both for OEM and aftermarket (retro-fitting) lamination to new and existing windows. Low level of

  10. 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.

  11. Bulk Crystal Growth of Piezoelectric PMN-PT Crystals Using Gradient Freeze Technique for Improved SHM Sensors

    Science.gov (United States)

    Aggarwal, Mohan D.; Kochary, F.; Penn, Benjamin G.; Miller, Jim

    2007-01-01

    There has been a growing interest in recent years in lead based perovskite ferroelectric and relaxor ferroelectric solid solutions because of their excellent dielectric, piezoelectric and electrostrictive properties that make them very attractive for various sensing, actuating and structural health monitoring (SHM) applications. We are interested in the development of highly sensitive and efficient PMN-PT sensors based on large single crystals for the structural health monitoring of composite materials that may be used in future spacecrafts. Highly sensitive sensors are needed for detection of defects in these materials because they often tend to fail by distributed and interacting damage modes and much of the damage occurs beneath the top surface of the laminate and not detectable by visual inspection. Research is being carried out for various combinations of solid solutions for PMN-PT piezoelectric materials and bigger size crystals are being sought for improved sensor applications. Single crystals of this material are of interest for sensor applications because of their high piezoelectric coefficient (d33 greater than 1700 pC/N) and electromechanical coefficients (k33 greater than 0.90). For comparison, the commonly used piezoelectric ceramic lead zirconate titanate (PZT) has a d33 of about 600 pC/N and electromechanical coefficients k33 of about 0.75. At the present time, these piezoelectric relaxor crystals are grown by high temperature flux growth method and the size of these crystals are rather small (3x4x5 mm(exp 3). In the present paper, we have attempted to grow bulk single crystals of PMN-PT in a 2 inch diameter platinum crucible and successfully grown a large size crystal of 67%PMN-33%PT using the vertical gradient freeze technique with no flux. Piezoelectric properties of the grown crystals are investigated. PMN-PT plates show excellent piezoelectric properties. Samples were poled under an applied electric field of 5 kV/cm. Dielectric properties at a

  12. Laser Schlieren Crystal-Growth Imager

    Science.gov (United States)

    Owen, R. B.; Johnston, M. H.

    1986-01-01

    Crystal observed as it grows from melt with aid of laser schlieren imaging. Observation method allows entire perimeter of growing crystal to be inspected. Isolated crystal facets examined, convection flows and temperature and concentration gradients revealed. Method does not require contact with, or proximity to, crystal.

  13. Holographic data storage crystals for the LDEF

    Science.gov (United States)

    Callen, W. Russell; Gaylord, Thomas K.

    1993-01-01

    Crystals of lithium niobate were passively exposed to the space environment of the Long Duration Exposure Facility (LDEF). Three of the four crystals contained volume holograms. Although the crystals suffered the surface damage characteristic of that suffered by other components on the Georgia Tech tray, the crystals remained suitable for the formation of volume holograms.

  14. Exploring Carbon Nanomaterial Diversity for Nucleation of Protein Crystals

    Science.gov (United States)

    Govada, Lata; Leese, Hannah S.; Saridakis, Emmanuel; Kassen, Sean; Chain, Benny; Khurshid, Sahir; Menzel, Robert; Hu, Sheng; Shaffer, Milo S. P.; Chayen, Naomi E.

    2016-02-01

    Controlling crystal nucleation is a crucial step in obtaining high quality protein crystals for structure determination by X-ray crystallography. Carbon nanomaterials (CNMs) including carbon nanotubes, graphene oxide, and carbon black provide a range of surface topographies, porosities and length scales; functionalisation with two different approaches, gas phase radical grafting and liquid phase reductive grafting, provide routes to a range of oligomer functionalised products. These grafted materials, combined with a range of controls, were used in a large-scale assessment of the effectiveness for protein crystal nucleation of 20 different carbon nanomaterials on five proteins. This study has allowed a direct comparison of the key characteristics of carbon-based nucleants: appropriate surface chemistry, porosity and/or roughness are required. The most effective solid system tested in this study, carbon black nanoparticles functionalised with poly(ethylene glycol) methyl ether of mean molecular weight 5000, provides a novel highly effective nucleant, that was able to induce crystal nucleation of four out of the five proteins tested at metastable conditions.

  15. Orientational bistability in ferronematic liquid crystals with negative diamagnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Zakhlevnykh, A.N., E-mail: anz@psu.ru; Petrov, D.A.

    2015-11-01

    In the framework of continuum theory we study magnetic field induced orientational transitions in a ferronematic, i.e. suspension of single-domain magnetic particles in a nematic liquid crystal. We consider the case of negative diamagnetic susceptibility anisotropy of a liquid crystal and soft planar coupling of impurity particles with a liquid crystal matrix. We found tricritical behavior of the threshold transition in a magnetic field from perturbed state into uniform planar state. This transition can be the first or second order, depending on the parameter of the magnetic phase segregation. We analytically derive the expression for the tricritical segregation parameter that determines the character of a transition. We show that ferronematic has a large magneto-optical non-linearity which is the result of the director reorientation under external field. Comparison of results of numerical calculations with experimental data has been carried out. - Highlights: • We study orientational and magnetooptical properties of ferronematics. • We obtain the phase diagram for soft coupling of nanoparticles and liquid crystal. • We examine the character of magnetic field induced orientational transitions. • We found tricritical behavior of the transition from perturbed to uniform state. • We study the optical phase lag and the capacity of ferronematic cell.

  16. A statistical approach for measuring dislocations in 2D photonic crystals

    DEFF Research Database (Denmark)

    Malureanu, Radu; Frandsen, Lars Hagedorn

    2008-01-01

    In this paper, a comparison between the placement accuracy of lattice atoms in photonic crystal structures fabricated with different lithographic techniques is made. Using atomic force microscopy measurements and self-developed algorithms for calculating the holes position within less than 0.01nm...

  17. Photoaligning and Photopatterning — A New Challenge in Liquid Crystal Photonics

    Directory of Open Access Journals (Sweden)

    Vladimir G. Chigrinov

    2013-03-01

    Full Text Available Photoalignment possesses obvious advantages in comparison with the usually “rubbing” treatment of the substrates of liquid crystal display (LCD cells. The application of the photoalignment and photopatterning nanotechnology for the new generation of photonic and display devices will be reviewed.

  18. Stacking fault energy in some single crystals

    Institute of Scientific and Technical Information of China (English)

    Aditya M.Vora

    2012-01-01

    The stacking fault energy of single crystals has been reported using the peak shift method.Presently studied all single crystals are grown by using a direct vapor transport (DVT) technique in the laboratory.The structural characterizations of these crystals are made by XRD.Considerable variations are shown in deformation (α) and growth (β) probabilities in single crystals due to off-stoichiometry,which possesses the stacking fault in the single crystal.

  19. Axial coherent bremsstrahlung of type A in a diamond crystal

    International Nuclear Information System (INIS)

    Axial coherent bremsstrahlung of type A (ACBA) has not been intensively investigated either theoretically or experimentally. Making use of the many-beam (two-dimensional quantum treatment) formalism for transversely bound electrons moving through crystal lattices, we have computed ACBA spectra for 17 MeV electrons passing through a 10 μm thick diamond (C) crystal. We found that the momentum transfer occurs in the plane perpendicular to the axis of interest. Only momentum transfers along the scan direction (electron transverse momentum direction) result in a photon emission in the forward direction. Two different scans have shown that the energies of the coherent bremsstrahlung peaks depend strongly on the direction of the electron transverse momentum. We also present a comparison of the first order Born approximation and the many-beam formalism

  20. Nanofluidics of Single-crystal Diamond Nanomechanical Resonators

    CERN Document Server

    Kara, V; Atikian, H; Yakhot, V; Loncar, M; Ekinci, K L

    2015-01-01

    Single-crystal diamond nanomechanical resonators are being developed for countless applications. A number of these applications require that the resonator be operated in a fluid, i.e., a gas or a liquid. Here, we investigate the fluid dynamics of single-crystal diamond nanomechanical resonators in the form of nanocantilevers. First, we measure the pressure-dependent dissipation of diamond nanocantilevers with different linear dimensions and frequencies in three gases, He, N$_2$, and Ar. We observe that a subtle interplay between the length scale and the frequency governs the scaling of the fluidic dissipation. Second, we obtain a comparison of the surface accommodation of different gases on the diamond surface by analyzing the dissipation in the molecular flow regime. Finally, we measure the thermal fluctuations of the nanocantilevers in water, and compare the observed dissipation and frequency shifts with theoretical predictions. These findings set the stage for developing diamond nanomechanical resonators o...

  1. Resonant coherent excitation of fast heavy ions in crystals

    Energy Technology Data Exchange (ETDEWEB)

    Moak, C.D.; Biggerstaff, J.A.; Crawford, O.H.

    1981-01-01

    Hydrogen-like ions of B, C, N, O and F and helium-like ions of N, O and F have been shown to exhibit resonant coherent excitation from their n = 1 to their n = 2 states, caused by periodic electric potential oscillations which occur as the ion moves through axial or planar chanels of a thin crystal of Au. The resonance velocities of the ions exhibit shifts and splittings which are the result of the crystal fields acting upon the one-, or two-electron ions. Comparisons with theory show fairly good agreement except for certain weak resonance components which do not appear or appear at unexpected values of the resonance velocity.

  2. Resonant coherent excitation of fast heavy ions in crystals

    International Nuclear Information System (INIS)

    Hydrogen-like ions of B, C, N, O and F and helium-like ions of N, O and F have been shown to exhibit resonant coherent excitation from their n = 1 to their n = 2 states, caused by periodic electric potential oscillations which occur as the ion moves through axial or planar chanels of a thin crystal of Au. The resonance velocities of the ions exhibit shifts and splittings which are the result of the crystal fields acting upon the one-, or two-electron ions. Comparisons with theory show fairly good agreement except for certain weak resonance components which do not appear or appear at unexpected values of the resonance velocity

  3. Chirped photonic crystals: a natural strategy for broadband reflectance

    CERN Document Server

    Cook, Caleb Q

    2016-01-01

    One-dimensional photonic crystals with slowly varying, i.e. "chirped", lattice period are responsible for broadband light reflectance in many diverse biological contexts, ranging from the shiny coatings of various beetles to the eyes of certain butterflies. We present a quantum scattering analogy for light reflection from these adiabatically chirped photonic crystals (ACPCs) and apply a WKB-type approximation to obtain a closed-form expression for the reflectance. From this expression we infer several design principles, including a differential equation for the chirp pattern required to elicit a given reflectance spectrum and the minimal number of bilayers required to exceed a desired reflectance threshold. Comparison of the number of bilayers found in ACPCs throughout nature and our predicted minimal required number also gives a quantitative measure of the optimality of chirped biological reflectors. Together these results elucidate the design principles of chirped reflectors in nature and their possible app...

  4. Axial coherent bremsstrahlung of type A in a diamond crystal

    Energy Technology Data Exchange (ETDEWEB)

    Chouffani, K. E-mail: khalid@athena.physics.isu.edu; Endo, I.; Ueberall, H

    2003-01-01

    Axial coherent bremsstrahlung of type A (ACBA) has not been intensively investigated either theoretically or experimentally. Making use of the many-beam (two-dimensional quantum treatment) formalism for transversely bound electrons moving through crystal lattices, we have computed ACBA spectra for 17 MeV electrons passing through a 10 {mu}m thick diamond (C) crystal. We found that the momentum transfer occurs in the plane perpendicular to the axis of interest. Only momentum transfers along the scan direction (electron transverse momentum direction) result in a photon emission in the forward direction. Two different scans have shown that the energies of the coherent bremsstrahlung peaks depend strongly on the direction of the electron transverse momentum. We also present a comparison of the first order Born approximation and the many-beam formalism.

  5. Loss of halogens from crystallized and glassy silicic volcanic rocks

    Science.gov (United States)

    Noble, D.C.; Smith, V.C.; Peck, L.C.

    1967-01-01

    One hundred and sixty-four F and Cl analyses of silicic welded tuffs and lavas and glass separates are presented. Comparison of the F and Cl contents of crystallized rocks with those of nonhydrated glass and hydrated glassy rocks from the same rock units shows that most of the halogens originally present were lost on crystallization. An average of about half of the F and four-fifths of the Cl originally present was lost. Analyses of hydrated natural glasses and of glassy rocks indicate that in some cases significant amounts of halogens may be removed from or added to hydrated glass through prolonged contact with ground water. The data show that the original halogen contents of the groundmass of a silicic volcanic rock can be reliably determined only from nonhydrated glass. ?? 1967.

  6. Prediction of molecular crystal structures

    International Nuclear Information System (INIS)

    The ab initio prediction of molecular crystal structures is a scientific challenge. Reliability of first-principle prediction calculations would show a fundamental understanding of crystallisation. Crystal structure prediction is also of considerable practical importance as different crystalline arrangements of the same molecule in the solid state (polymorphs)are likely to have different physical properties. A method of crystal structure prediction based on lattice energy minimisation has been developed in this work. The choice of the intermolecular potential and of the molecular model is crucial for the results of such studies and both of these criteria have been investigated. An empirical atom-atom repulsion-dispersion potential for carboxylic acids has been derived and applied in a crystal structure prediction study of formic, benzoic and the polymorphic system of tetrolic acid. As many experimental crystal structure determinations at different temperatures are available for the polymorphic system of paracetamol (acetaminophen), the influence of the variations of the molecular model on the crystal structure lattice energy minima, has also been studied. The general problem of prediction methods based on the assumption that the experimental thermodynamically stable polymorph corresponds to the global lattice energy minimum, is that more hypothetical low lattice energy structures are found within a few kJ mol-1 of the global minimum than are likely to be experimentally observed polymorphs. This is illustrated by the results for molecule I, 3-oxabicyclo(3.2.0)hepta-1,4-diene, studied for the first international blindtest for small organic crystal structures organised by the Cambridge Crystallographic Data Centre (CCDC) in May 1999. To reduce the number of predicted polymorphs, additional factors to thermodynamic criteria have to be considered. Therefore the elastic constants and vapour growth morphologies have been calculated for the lowest lattice energy structures

  7. Prediction of molecular crystal structures

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, Theresa

    2001-07-01

    The ab initio prediction of molecular crystal structures is a scientific challenge. Reliability of first-principle prediction calculations would show a fundamental understanding of crystallisation. Crystal structure prediction is also of considerable practical importance as different crystalline arrangements of the same molecule in the solid state (polymorphs)are likely to have different physical properties. A method of crystal structure prediction based on lattice energy minimisation has been developed in this work. The choice of the intermolecular potential and of the molecular model is crucial for the results of such studies and both of these criteria have been investigated. An empirical atom-atom repulsion-dispersion potential for carboxylic acids has been derived and applied in a crystal structure prediction study of formic, benzoic and the polymorphic system of tetrolic acid. As many experimental crystal structure determinations at different temperatures are available for the polymorphic system of paracetamol (acetaminophen), the influence of the variations of the molecular model on the crystal structure lattice energy minima, has also been studied. The general problem of prediction methods based on the assumption that the experimental thermodynamically stable polymorph corresponds to the global lattice energy minimum, is that more hypothetical low lattice energy structures are found within a few kJ mol{sup -1} of the global minimum than are likely to be experimentally observed polymorphs. This is illustrated by the results for molecule I, 3-oxabicyclo(3.2.0)hepta-1,4-diene, studied for the first international blindtest for small organic crystal structures organised by the Cambridge Crystallographic Data Centre (CCDC) in May 1999. To reduce the number of predicted polymorphs, additional factors to thermodynamic criteria have to be considered. Therefore the elastic constants and vapour growth morphologies have been calculated for the lowest lattice energy

  8. 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.

  9. Effects of Annealing Treatments on Luminescence and Scintillation Properties of Ce:Lu3Al5O12 Crystal Grown by Czochralski Method

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Ce:Lu3Al5O12 single crystals grown in pure N2 atmosphere by Czochralski method were annealed in oxidizing atmosphere (air) and reducing atmosphere (H2+N2), respectively. Effects of annealing treatments on luminescence and scintillation properties of the crystals were investigated. The crystal annealed in air showed the highest luminescence intensity under blue light or vacuum ultraviolet excitation in comparison with that annealed in reducing flux or the as-grown crystal. Under X-ray excitation, crystal annealed in reducing atmosphere had the lowest light yield, and crystal annealed in air had the fastest decay time under 137Cs 662 keV γ-ray excitation. Different annealing treatments resulted in different luminescence and scintillation properties, which might related with oxygen vacancies or defect existing in the crystals.

  10. Hot Views on Cold Crystals: The Application of Thermal Imaging in Cryo-crystallography

    Science.gov (United States)

    Snell, E. H.; vanderWoerd, M. J.; Deacon, A.

    2003-01-01

    In the past we have used thermal imaging techniques to visualize the cryocooling processes of macromolecular crystals. From these images it was clear that a cold wave progresses through a crystal starting at the face closest to the origin of the cold stream and ending at the point furthest away. During these studies we used large volume crystals, which were clearly distinguished from the loop holding them. These large crystals, originally grown for neutron diffraction studies, were chosen deliberately to enhance the imaging. As an extension to this work, we present used thermal imaging to study small crystals, held in a cryo-loop, in the presence of vitrified mother liquor. The different infrared transmission and reflectance properties of the crystal in comparison to the mother liquor surrounding it are thought to be the parameter that produces the contrast that makes the crystal visible. An application of this technology may be the determination of the exact location of small crystals in a cryo-loop. Data from initial tests in support of application development was recorded for lysozyme crystals and for bFGF/dna complex crystals, which were cryo-cooled and imaged in large loops, both with visible light and with infrared radiation. The crystals were clearly distinguished from the vitrified solution in the infrared spectrum, while in the case of the bFGF/dna complex the illumination had to be carefully manipulated to make the crystal visible in the visible spectrum. These results suggest that the thermal imaging may be more sensitive than visual imaging for automated location of small crystals. However, further work on small crystals robotically mounted at SSRL did not clearly visualize those crystals. The depth of field of the camera proved to be limiting and a different cooling geometry was used, compared to the previous, successful experiments. Analysis to exploit multiple images to improve depth of field and experimental work to understand cooling geometry

  11. Crystal structure of natural orthorhombic Ag.sub.0.71./sub.Pb.sub.1.52./sub.Bi.sub.1.32./sub.Sb.sub.1.45./sub.S.sub.6./sub., a lillianite homologue with N=4; comparison with gustavite

    Czech Academy of Sciences Publication Activity Database

    Pažout, R.; Dušek, Michal

    2010-01-01

    Roč. 22, č. 5 (2010), s. 741-750. ISSN 0935-1221 R&D Projects: GA ČR GA205/07/0302 Institutional research plan: CEZ:AV0Z10100521 Keywords : crystal structure * orthorhombic lillianite homologue with N= 4 * Bi-Sb sulphosalt * Kutná Hora ore district Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.469, year: 2010

  12. The effect of seed crystals of hydroxyapatite and brushite on the crystallization of calcium oxalate in undiluted human urine in vitro: implications for urinary stone pathogenesis.

    Science.gov (United States)

    Grover, Phulwinder K.; Kim, Dong-Sun; Ryall, Rosemary Lyons

    2002-01-01

    BACKGROUND: The aim of this study was to determine whether crystals of hydroxyapatite (HA) or brushite (BR) formed in urine promote the epitaxial deposition of calcium oxalate (CaOx) from undiluted human urine in vitro and thereby explain the occurrence of phosphate in the core of urinary stones consisting predominantly of CaOx. MATERIALS AND METHODS: Crystals of HA, BR, and CaOx were generated from human urine and their identity confirmed by X-ray analysis. Standard quantities of each crystal were then added to separate aliquots of pooled undiluted human urine and CaOx crystallization was induced by the addition of identical loads of sodium oxalate. Crystallization was monitored by Coulter Counter and (14) C-oxalate analysis and the precipitated crystals were examined by scanning electron microscopy. RESULTS: In comparison with the control to which no seeds were added, addition of CaOx crystals increased the deposition of (14) C-oxalate by 23%. On the other hand, seeds of HA and BR had no effect. These findings were supported by Coulter Counter analysis, which showed that the average modal sizes of crystal particles precipitated in the presence of HA and BR seeds were indistinguishable from those in the control, whereas those deposited in the presence of CaOx were significantly larger. Scanning electron microscopy confirmed these results, demonstrating that large aggregates of CaOx dihydrates were formed in the presence of CaOx seeds, whereas BR and to a lesser extent HA seeds were scattered free on the filtration membrane and attached like barnacles on the surface of the freshly precipitated CaOx crystals. CONCLUSION: Seed crystals of HA or BR do not promote CaOx deposition in urine in vitro and are therefore unlikely to influence CaOx crystal formation under physiologic conditions. However, binding of HA and BR crystals to, and their subsequent enclosure within, actively growing CaOx crystals might occur in vivo, thereby explaining the occurrence of mixed

  13. Supramolecular chemistry and crystal engineering

    Indian Academy of Sciences (India)

    Ashwini Nangia

    2010-05-01

    Advances in supramolecular chemistry and crystal engineering reported from India within the last decade are highlighted in the categories of new intermolecular interactions, designed supramolecular architectures, network structures, multi-component host-guest systems, cocrystals, and polymorphs. Understanding self-assembly and crystallization through X-ray crystal structures is illustrated by two important prototypes - the large unit cell of elusive saccharin hydrate, Na16(sac)16 . 30H2O, which contains regular and irregular domains in the same structure, and by the Aufbau build up of zinc phosphate framework structures, e.g. ladder motif in [C3N2H12][Zn(HPO4)2] to layer structure in [C3N2H12][Zn2(HPO4)3] upon prolonged hydrothermal conditions. The pivotal role of accurate X-ray diffraction in supramolecular and structural studies is evident in many examples. Application of the bottomup approach to make powerful NLO and magnetic materials, design of efficient organogelators, and crystallization of novel pharmaceutical polymorphs and cocrystals show possible future directions for interdisciplinary research in chemistry with materials and pharmaceutical scientists. This article traces the evolution of supramolecular chemistry and crystal engineering starting from the early nineties and projects a center stage for chemistry in the natural sciences.

  14. Role of Solvents in Improvement of Dissolution Rate of Drugs: Crystal Habit and Crystal Agglomeration

    Directory of Open Access Journals (Sweden)

    Maryam Maghsoodi

    2015-03-01

    Full Text Available Crystallization is often used for manufacturing drug substances. Advances of crystallization have achieved control over drug identity and purity, but control over the physical form remains poor. This review discusses the influence of solvents used in crystallization process on crystal habit and agglomeration of crystals with potential implication for dissolution. According to literature it has been known that habit modification of crystals by use of proper solvents may enhance the dissolution properties by changing the size, number and the nature of crystal faces exposed to the dissolution medium. Also, the faster dissolution rate of drug from the agglomerates of crystals compared with the single crystals may be related to porous structure of the agglomerates and consequently their better wettability. It is concluded from this review that in-depth understanding of role of the solvents in crystallization process can be applied to engineering of crystal habit or crystal agglomeration, and predictably dissolution improvement in poorly soluble drugs.

  15. Tunable Photonic Band Gaps In Photonic Crystal Fibers Filled With a Cholesteric Liquid Crystal

    Institute of Scientific and Technical Information of China (English)

    Thomas; Tanggaard; Larsen; David; Sparre; Hermann; Anders; Bjarklev

    2003-01-01

    A photonic crystal fiber has been filled with a cholesteric liquid crystal. A temperature sensitive photonic band gap effect was observed, which was especially pronounced around the liquid crystal phase transition temperature.

  16. Studies of relativistic electron scattering at planar alignment in a thin Si crystal

    Energy Technology Data Exchange (ETDEWEB)

    Takabayashi, Y. [SAGA Light Source, 8-7 Yayoigaoka, Tosu, Saga 841-0005 (Japan); Pivovarov, Yu.L.; Tukhfatullin, T.A. [National Research Tomsk Polytechnic University, Tomsk (Russian Federation)

    2014-04-01

    Experiments on 255-MeV electron scattering under (220) planar channeling conditions in a Si crystal were carried out at the linac of the SAGA Light Source. The spatial and angular distributions of electrons penetrating through a 20-μm thick Si crystal at different incident angles with respect to the (220) plane were measured, and features characteristic of the planar alignment were identified. The experimental results were compared with computer simulations, and showed a reasonable agreement. A comparison with doughnut scattering at axial channeling in the same crystal was also performed. It was confirmed that the planar alignment effect is weaker than the axial alignment effect. These studies are important for understanding the basic mechanism of electron scattering and radiation processes in a crystal.

  17. Mean-field solution of the Blume–Capel model under a random crystal field

    Energy Technology Data Exchange (ETDEWEB)

    Santos, P.V., E-mail: priscilavs65@yahoo.com.br; Costa, F.A. da, E-mail: fcosta@dfte.ufrn.br; Araújo, J.M. de, E-mail: joaomedeiros@dfte.ufrn.br

    2015-07-17

    In this work we investigate the Blume–Capel model with infinite-range ferromagnetic interactions and under the influence of a quenched disorder – a random crystal field. For a suitable choice of the random crystal field the model displays a wealth of multicritical behavior, continuous and first-order transition lines, as well as re-entrant behavior. The resulting phase diagrams show a variety of topologies as a function of the disorder parameter p. A comparison with recent results on the Blume–Capel model in random crystal field is discussed. - Highlights: • We introduce a disordered exactly soluble version of the Blume–Capel model with infinite-range interactions. • The disorder is represented by quenched random crystal field anisotropy. • A classification of phase diagrams in terms of their topology is presented. • The effects of randomness on critical and multicritical phenomena are investigated.

  18. Sublimation rate of molecular crystals - role of internal degrees of freedom

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, A; Zepeda-Ruiz, L A; Gee, R H; Burnham, A

    2007-01-19

    It is a common practice to estimate site desorption rate from crystal surfaces with an Arrhenius expression of the form v{sub eff} exp(-{Delta}E/k{sub B}T), where {Delta}E is an activation barrier to desorb and v{sub eff} is an effective vibrational frequency {approx} 10{sup 12} sec{sup -1}. However, such a formula can lead to several to many orders of magnitude underestimation of sublimation rates in molecular crystals due to internal degrees of freedom. We carry out a quantitative comparison of two energetic molecular crystals with crystals of smaller entities like ice and Argon (solid) and uncover the errors involved as a function of molecule size. In the process, we also develop a formal definition of v{sub eff} and an accurate working expression for equilibrium vapor pressure.

  19. Statistical description of response to flood-field irradiation in scintillation crystal arrays

    International Nuclear Information System (INIS)

    Images obtained by flood-field Co57 irradiation of CsI(Tl) crystal arrays detectors, coupled to a metal-channel dynode PSPMT, were statistically analyzed by means of a bivariate normal distribution. For each crystal position, the planar distribution charge was described by a confidence ellipse chosen to maximize the 1-to-1 relationship between the photons incoming at each crystal and the centroid obtained from electric charge distribution. The flood-field irradiation response of a 22 mmx22 mm CsI(Tl) array, with different pixel dimensions, were studied, and the comparison between the charge distribution of a limited number of crystals following the flood-field irradiation was made

  20. Mean-field solution of the Blume–Capel model under a random crystal field

    International Nuclear Information System (INIS)

    In this work we investigate the Blume–Capel model with infinite-range ferromagnetic interactions and under the influence of a quenched disorder – a random crystal field. For a suitable choice of the random crystal field the model displays a wealth of multicritical behavior, continuous and first-order transition lines, as well as re-entrant behavior. The resulting phase diagrams show a variety of topologies as a function of the disorder parameter p. A comparison with recent results on the Blume–Capel model in random crystal field is discussed. - Highlights: • We introduce a disordered exactly soluble version of the Blume–Capel model with infinite-range interactions. • The disorder is represented by quenched random crystal field anisotropy. • A classification of phase diagrams in terms of their topology is presented. • The effects of randomness on critical and multicritical phenomena are investigated

  1. Last crystals for the CMS chandelier

    CERN Multimedia

    2008-01-01

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

  2. Titania single crystals with a curved surface

    Science.gov (United States)

    Yang, Shuang; Yang, Bing Xing; Wu, Long; Li, Yu Hang; Liu, Porun; Zhao, Huijun; Yu, Yan Yan; Gong, Xue Qing; Yang, Hua Gui

    2014-11-01

    Owing to its scientific and technological importance, crystallization as a ubiquitous phenomenon has been widely studied over centuries. Well-developed single crystals are generally enclosed by regular flat facets spontaneously to form polyhedral morphologies because of the well-known self-confinement principle for crystal growth. However, in nature, complex single crystalline calcitic skeleton of biological organisms generally has a curved external surface formed by specific interactions between organic moieties and biocompatible minerals. Here we show a new class of crystal surface of TiO2, which is enclosed by quasi continuous high-index microfacets and thus has a unique truncated biconic morphology. Such single crystals may open a new direction for crystal growth study since, in principle, crystal growth rates of all facets between two normal {101} and {011} crystal surfaces are almost identical. In other words, the facet with continuous Miller index can exist because of the continuous curvature on the crystal surface.

  3. Reconstruction of the concentration field around a growing KDP crystal with schlieren tomography

    International Nuclear Information System (INIS)

    Salt concentration distribution around a potassium dihydrogen phosphate (KDP) crystal growing from its aqueous solution has been experimentally determined using a laser schlieren technique. The growth process is initiated by inserting a KDP seed into its supersaturated solution, followed by slow cooling of the solution. Fluid convection leads to a distribution of concentration around the growing crystal. The pattern and strength of convection are important factors for the determination of the crystal growth rate and quality. Experiments have been conducted in a beaker with a diameter of 16.5 cm and a height of 23 cm. A monochrome schlieren technique has been employed to image the concentration field from four view angles, namely, 0 deg., 45 deg., 90 deg., and 135 deg. By interpreting the schlieren images as projection data of the solute concentration, the three-dimensional concentration field around the crystal has been determined using the convolution backprojection algorithm. The suitability of the overall approach has been validated using a simulated convective field in a circular differentially heated fluid layer, where full as well as partial data are available. Experiments have been conducted in the convection-dominated regime of crystal growth. The noncircular shape of the crystal is seen to affect axisymmetry of the concentration field close to the crystal surface. The reconstructed concentration fields reveal symmetry of the flow field away from the growing crystal. The solute concentration contours show large growth rates of the side faces of the crystal in comparison with the horizontal faces. In this respect, the concentration profiles are seen to correlate with the crystal geometry

  4. Coherent thermal conductance of 1-D photonic crystals

    Science.gov (United States)

    Tschikin, Maria; Ben-Abdallah, Philippe; Biehs, Svend-Age

    2012-10-01

    We present an exact calculation of coherent thermal conductance in 1-D multilayer photonic crystals using the S-matrix method. In particular, we study the thermal conductance in a bilayer structure of Si/vacuum or Al2O3/vacuum slabs by means of the exact radiative heat flux expression. Based on the results obtained for the Al2O3/vacuum structure we show by comparison with previous works that the material losses and (localized) surface modes supported by the inner layers play a fundamental role and cannot be omitted in the definition of thermal conductance. Our results could have significant implications in the conception of efficient thermal barriers.

  5. Lateral shift in one-dimensional quasiperiodic chiral photonic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Da, Jian, E-mail: dajian521@sina.com [Department of Information Engineering, Huaian Senior Vocational and Technical School, Feiyao road, Huaian 223005, Jiangsu Province (China); Mo, Qi, E-mail: moqiyueyang@163.com [School of Software, Yunnan University, Cuihu Bai Road, Kunming City, Yunnan Province 650091 (China); Cheng, Yaokun [Department of Information Engineering, Huaian Senior Vocational and Technical School, Feiyao road, Huaian 223005, Jiangsu Province (China); Liu, Taixiang [Taishan Vocational College of Nursing, Shandong Province 271000 (China)

    2015-02-01

    We investigate the lateral shift of a one-dimensional quasiperiodic photonic crystal consisting of chiral and conventional dielectric materials. The effect of structural irregularity on lateral shift is evaluated by stationary-phase approach. Our results show that the lateral shift can be modulated by varying the structural irregularity in quasiperiodic structure. Besides, the position of peak in lateral shift spectrum stays sensitive to the chiral factor of chiral materials. In comparison with that of periodic structure, quasiperiodic structure provides an extra degree of freedom to manipulate the lateral shift.

  6. Luneburg and flat lens based on graded photonic crystal

    Science.gov (United States)

    Liu, Wei; Sun, Xiaohong; Gao, Minglei; Wang, Shuai

    2016-04-01

    Square-lattice graded photonic crystals employed for designing Luneburg and Flat Lens is presented. Comparable simulation of the Luneburg lens with TE and TM polarizations predicts that TM lens possesses of enlarged transmission bandwidth and strengthened focusing ability, in comparison with TE lens. As a typical simplified counterpart, the evolution of focusing intensity and numerical aperture of the flat lens is achieved. What is more, those Luneburg and Flat Lens can withstand imperfect gradients in structure design. This will provide a guidance to produce a high quality focusing lens with small size, short focal length and large numerical aperture applied in the integrated photonic devices.

  7. Coherent thermal conductance of 1-D photonic crystals

    International Nuclear Information System (INIS)

    We present an exact calculation of coherent thermal conductance in 1-D multilayer photonic crystals using the S-matrix method. In particular, we study the thermal conductance in a bilayer structure of Si/vacuum or Al2O3/vacuum slabs by means of the exact radiative heat flux expression. Based on the results obtained for the Al2O3/vacuum structure we show by comparison with previous works that the material losses and (localized) surface modes supported by the inner layers play a fundamental role and cannot be omitted in the definition of thermal conductance. Our results could have significant implications in the conception of efficient thermal barriers.

  8. Crystal Structure of Three Compounds Related to Triphenylene and Tetracyanoquinodimethane

    DEFF Research Database (Denmark)

    Andresen, T.L.; Krebs, Frederik C; Larsen, M.; Thorup, Niels

    1999-01-01

    The crystal structures of a charge-transfer complex of triphenylene with 1,3,5-tris(2,2-dicyanovinyl) benzene (1), a complex of 2,3,6,7,10,11-hexamethoxytriphenylene with 2,5-dichlorotetracyanoquinodimethane (2) and also 2,5-dichlorotetracyanoquinodimethane itself (3) have been determined. Compou......,2-dichlorobenzene solvent molecules. Weak hydrogen bonds are present in the structures of 1 and 2. Based on comparisons of bond lengths the electronic charge-transfer in 2 has been estimated to be about 0.3 e. The synthesis of 1,3,5-tris(2,2-dicyanovinyl) benzene is also reported....

  9. Growth of bulk gadolinium pyrosilicate single crystals for scintillators

    Science.gov (United States)

    Gerasymov, I.; Sidletskiy, O.; Neicheva, S.; Grinyov, B.; Baumer, V.; Galenin, E.; Katrunov, K.; Tkachenko, S.; Voloshina, O.; Zhukov, A.

    2011-03-01

    Ce, Pr, and La-doped gadolinium pyrosilicate Gd2Si2O7 (GPS) single crystals were grown by the Czochralski and Top Seeded Solution Growth (TSSG) techniques for the first time. Formation conditions of different pyrosilicate phases were determined. X-ray luminescence integral intensity of Ce-doped GPS is about one order of magnitude higher in comparison with gadolinium oxyorthosilicate Gd2SiO5:Ce (GSO:Ce). All samples demonstrate temperature stability of luminescence yield up to 400 K.

  10. Phoxonic crystals and cavity optomechanics

    Science.gov (United States)

    Djafari-Rouhani, Bahram; El-Jallal, Said; Pennec, Yan

    2016-05-01

    Phoxonic crystals are dual phononic/photonic crystals exhibiting simultaneously band gaps for both types of excitations. Therefore, they have the ability to confine phonons and photons in the same cavity and in turn allow the enhancement of their interaction. In this paper, we review some of our theoretical works on cavity optomechanical interactions in different types of phoxonic crystals, including two-dimensional, slab, and nanobeam structures. Two mechanisms are behind the phonon-photon interaction, namely the photoelastic and the moving interface effects. Coupling rates of a few MHz are obtained with high-frequency phonons of a few GHz. Finally, we give some preliminary results about the optomechanical interaction when a metallic nanoparticle is introduced into the cavity, giving rise to coupled photon-plasmon modes or, in the case of very small particles, to an enhancement of the electric field at the position of the particle. xml:lang="fr"

  11. Diamond based photonic crystal microcavities.

    Science.gov (United States)

    Tomljenovic-Hanic, S; Steel, M J; de Sterke, C Martijn; Salzman, J

    2006-04-17

    Diamond based technologies offer a material platform for the implementation of qubits for quantum computing. The photonic crystal architecture provides the route for a scalable and controllable implementation of high quality factor (Q) nanocavities, operating in the strong coupling regime for cavity quantum electrodynamics. Here we compute the photonic band structures and quality factors of microcavities in photonic crystal slabs in diamond, and compare the results with those of the more commonly-used silicon platform. We find that, in spite of the lower index contrast, diamond based photonic crystal microcavities can exhibit quality factors of Q=3.0x10(4), sufficient for proof of principle demonstrations in the quantum regime. PMID:19516502

  12. Crystal structure determination of Efavirenz

    Energy Technology Data Exchange (ETDEWEB)

    Popeneciu, Horea, E-mail: horea.popeneciu@itim-cj.ro; Dumitru, Ristoiu [College of Environmental Science on Engineering Babes Bolyai University, 30 Fantanele, 400294 Cluj Napoca (Romania); Tripon, Carmen, E-mail: horea.popeneciu@itim-cj.ro; Borodi, Gheorghe, E-mail: horea.popeneciu@itim-cj.ro; Pop, Mihaela Maria, E-mail: mihaelapop@teracrystal.com

    2015-12-23

    Needle-shaped single crystals of the title compound, C{sub 14}H{sub 9}ClF{sub 3}NO{sub 2}, were obtained from a co-crystallization experiment of Efavirenz with maleic acid in a (1:1) ratio, using methanol as solvent. Crystal structure determination at room temperature revealed a significant anisotropy of the lattice expansion compared to the previously reported low-temperature structure. In both low- and room temperature structures the cyclopropylethynyl fragment in one of the asymmetric unit molecules is disordered. While at low-temperature only one C atom exhibits positional disorder, at room temperature the disorder is present for two C atoms of the cyclopropane ring.

  13. Plasmonic crystal demultiplexer and multiports

    CERN Document Server

    Drezet, Aurelien; Hohenau, Andreas; Leitner, Alfred; Aussenegg, Franz R; Krenn, Joachim R

    2010-01-01

    Artificially built periodic optical structures in dielectric and metallic media have generated considerable interest due to their potential for optical device miniaturization. In this context plasmonics, i.e., optics based on surface plasmon polaritons (SPPs) offers new exciting prospects. SPPs are hybrid light/electron surface waves at the interface between a dielectric and a metal and as such hold the potential for 2D optical functionality. Indeed, SPP elements as mirrors, splitters and interferometers have been recently demonstrated. However, for plasmonics to qualify at the information technology level requires necessarily the realization of wavelength division (demultiplexing) which constitutes a fundamental ingredient of optical communication. In the following we experimentally demonstrate 2D SPP demultiplexing in the visible spectral range by using photonic crystals for SPPs (plasmonic crystals). In addition, we demonstrate that plasmonic crystal are capable of realizing integrated linear multiports wh...

  14. Effect of crystal habit on the dissolution behaviour of simvastatin crystals and its relationship to crystallization solvent properties.

    Science.gov (United States)

    Bukovec, P; Benkic, P; Smrkolj, M; Vrecer, F

    2016-05-01

    Simvastatin crystals, having same crystal structure but different types of habits and hence different intrinsic dissolution rate, were prepared by recrystallization from solvents selected according to their polarity index. Scanning electron microscopy, laser diffraction, image analysis, X-ray powder diffractometry, Fourier transform infrared spectroscopy and differential scanning calorimetry were used to investigate the physicochemical characteristics of the prepared crystals. The isolated crystals exhibited different crystal habits but possessed the same internal crystal structure. In this study the comparative intrinsic dissolution behaviour of the simvastatin crystals with different types of habits was studied and explained by surface energy and correlated to different solvent systems that were used for crystallization. In our work we diminished the influence of all other physical parameters that could influence the dissolution rate, e.g. particle size, specific surface area and polymorphism in order to focus the study onto the impact of crystal shape itself on the dissolution rate of simvastatin crystals. Rod shaped crystals isolated from more hydrophilic solvent mixture dissolved faster than plate-like crystals obtained from solvent mixture with lower polarity index. We correlated this fact to the different growth rate of the individual faces which resulted in different relative size of the individual crystal faces exposed to the dissolution medium as well as the chemical nature of those faces which in turn influenced the wettability and subsequent dissolution of the active pharmaceutical ingredient. PMID:27348970

  15. Benchmark of the FLUKA model of crystal channeling against the UA9-H8 experiment

    International Nuclear Information System (INIS)

    Channeling in bent crystals is increasingly considered as an option for the collimation of high-energy particle beams. The installation of crystals in the LHC has taken place during this past year and aims at demonstrating the feasibility of crystal collimation and a possible cleaning efficiency improvement. The performance of CERN collimation insertions is evaluated with the Monte Carlo code FLUKA, which is capable to simulate energy deposition in collimators as well as beam loss monitor signals. A new model of crystal channeling was developed specifically so that similar simulations can be conducted in the case of crystal-assisted collimation. In this paper, most recent results of this model are brought forward in the framework of a joint activity inside the UA9 collaboration to benchmark the different simulation tools available. The performance of crystal STF 45, produced at INFN Ferrara, was measured at the H8 beamline at CERN in 2010 and serves as the basis to the comparison. Distributions of deflected particles are shown to be in very good agreement with experimental data. Calculated dechanneling lengths and crystal performance in the transition region between amorphous regime and volume reflection are also close to the measured ones

  16. Presentation and investigation of a new two dimensional heterostructure phononic crystal to obtain extended band gap

    Science.gov (United States)

    Bagheri Nouri, Mohammad; Moradi, Mehran

    2016-05-01

    In this paper, a new heterostructure phononic crystal is introduced. The new heterostructure is composed of square and rhombus phononic crystals. Using finite difference method, a displacement-based algorithm is presented to study elastic wave propagation in the phononic crystal. In contrast with conventional finite difference time domain method, at first by using constitutive equations and strain-displacement relations, elastic wave equations are derived based on displacement. Then, these forms are discretized using finite difference method. By this technique, components of stress tensor can be removed from the updating equations. Since the proposed method needs less elementary arithmetical operations, its computational cost is less than that of the conventional FDTD method. Using the presented displacement-based finite difference time domain algorithm, square phononic crystal, rhombus phononic crystal and the new heterostructure phononic crystal were analyzed. Comparison of transmission spectra of the new heterostructure phononic crystal with those creating lattices, showed that band gap can be extended by using the new structure. Also it was observed that by changing the angular constant of rhombus lattice, a new extended band gap can be achieved.

  17. Characterization of a newly synthesized organic nonlinear optical crystal: benzoyl valine

    Science.gov (United States)

    Kumar, T. K.; Selvaraj, R. S.; Janarthanan, S.; Rajan, Y. C.; Selvakumar, S.; Pandi, S.; Selvakumar, M. S.; Anand, D. P.

    2010-05-01

    Herein the synthesis and the crystal growth of benzoyl valine (BV), an organic nonlinear optical (NLO) material for frequency conversion was grown by slow evaporation solution growth technique at room temperature has been reported. The compound was prepared by Stockman method of benzoylation. The solubility curve shows linear nature up to a temperature of 313 K. XRD study reveals that the crystal belongs to monoclinic system with P21 non-centrosymmetric space group. The fundamental vibrational frequency of various functional groups (400-4000 cm-1) in the crystal was determined from FTIR analysis. 1H and 13C NMR spectral studies reveal the presence of proton and carbon network in the grown crystalline sample. The optical behaviour of the crystal was ascertained by optical UV absorption spectral studies. The UV cut off region (λmax) lies around 200 nm and the crystal is absolutely transparent from 220-800 nm suggesting its application as NLO material. The thermal stability of the crystal was determined by thermogravimetric and differential thermal analyses. Laser damage threshold of BV was found to be 0.34 GW/cm2 and hence BV can be used in frequency doubler system. Photoconductivity study of BV revealed negative photoconductiviting nature of the sample. The microhardness studies confirm that BV has a moderate Vickers hardness number (VHN) value in comparison to the other organic NLO crystals.

  18. Multiple solvent crystal structures of ribonuclease A: An assessment of the method

    Energy Technology Data Exchange (ETDEWEB)

    Dechene, Michelle; Wink, Glenna; Smith, Mychal; Swartz, Paul; Mattos, Carla; (NCSU)

    2010-11-12

    The multiple solvent crystal structures (MSCS) method uses organic solvents to map the surfaces of proteins. It identifies binding sites and allows for a more thorough examination of protein plasticity and hydration than could be achieved by a single structure. The crystal structures of bovine pancreatic ribonuclease A (RNAse A) soaked in the following organic solvents are presented: 50% dioxane, 50% dimethylformamide, 70% dimethylsulfoxide, 70% 1,6-hexanediol, 70% isopropanol, 50% R,S,R-bisfuran alcohol, 70% t-butanol, 50% trifluoroethanol, or 1.0M trimethylamine-N-oxide. This set of structures is compared with four sets of crystal structures of RNAse A from the protein data bank (PDB) and with the solution NMR structure to assess the validity of previously untested assumptions associated with MSCS analysis. Plasticity from MSCS is the same as from PDB structures obtained in the same crystal form and deviates only at crystal contacts when compared to structures from a diverse set of crystal environments. Furthermore, there is a good correlation between plasticity as observed by MSCS and the dynamic regions seen by NMR. Conserved water binding sites are identified by MSCS to be those that are conserved in the sets of structures taken from the PDB. Comparison of the MSCS structures with inhibitor-bound crystal structures of RNAse A reveals that the organic solvent molecules identify key interactions made by inhibitor molecules, highlighting ligand binding hot-spots in the active site. The present work firmly establishes the relevance of information obtained by MSCS.

  19. Liquid crystal alignment on excimer laser irradiated polyimide

    International Nuclear Information System (INIS)

    Grating and photoinduced anisotropic modifications are made to polyimide layers to promote homogeneous and pretilted nematic liquid crystal alignment. Gratings are etched into the polyimide by irradiating a phase mask of period 1.1 μm with the output from a KrF excimer laser of wavelength 248 nm with fluences above the threshold required for ablation. Grating depths from 10 to 190 nm have been achieved using a simple pulse from the laser, and the liquid crystal azimuthal anchoring energy is determined as a function of the grating depth. Values up to 1.3 x 10-5 Jm-2 are found. Discrepancies are found when comparisons are made between experimental data and a theory based upon elastic strain energy minimisation. A modified theory taking finite polar anchoring into account shows better agreement. Polarised excimer laser radiation at normal incidence is used to induce an anisotropy which gives rise to homogeneous liquid crystal alignment. The strength of the azimuthal anchoring energy is similar to that produced by grating alignment. Spectroscopic analysis reveals that the alignment originates from the stronger depletion of polyimide chains parallel to the exposure polarisation direction. The dependence of beam fluence and exposure time on the anchoring energy is measured, and the degradation mechanism of the polyimide is investigated as a function of the exposure. We find that oxidative degradation takes place. We also use these techniques to identify the chemical composition of the polyimide material. Pretilted liquid crystal alignment has also been achieved, with pretilt angles up to 3.7 deg. A tilted polymer distribution is generated by oblique exposure of the polyimide to an elliptically polarised beam. We measure the liquid crystal pretilt angle as a function of the angle of incidence, and exposure time and present a theoretical analysis of the polyimide chain azimuthal distribution which agrees with the experimental results. Finally, a simple and novel technique

  20. Fundamentals of liquid crystal devices

    CERN Document Server

    Yang, Deng-Ke

    2014-01-01

    Revised throughout to cover the latest developments in the fast moving area of display technology, this 2nd edition of Fundamentals of Liquid Crystal Devices, will continue to be a valuable resource for those wishing to understand the operation of liquid crystal displays. Significant updates include new material on display components, 3D LCDs and blue-phase displays which is one of the most promising new technologies within the field of displays and it is expected that this new LC-technology will reduce the response time and the number of optical components of LC-modules. Prof. Yang is a pion

  1. Quantum crystals and spin chains

    Energy Technology Data Exchange (ETDEWEB)

    Dijkgraaf, Robbert [KdV Institute for Mathematics, University of Amsterdam, Plantage Muidergracht 24, 1018 TV Amsterdam (Netherlands); Institute for Theoretical Physics, University of Amsterdam, Valckenierstraat 65, 1018 XE Amsterdam (Netherlands); Orlando, Domenico [Institut de Physique, Universite de Neuchatel, Rue Breguet 1, CH-2000 Neuchatel (Switzerland); Reffert, Susanne [Institute for Theoretical Physics, University of Amsterdam, Valckenierstraat 65, 1018 XE Amsterdam (Netherlands)], E-mail: sreffert@gmail.com

    2009-04-21

    In this article, we discuss the quantum version of the melting crystal corner in one, two, and three dimensions, generalizing the treatment for the quantum dimer model. Using a mapping to spin chains we find that the two-dimensional case (growth of random partitions) is integrable and leads directly to the Hamiltonian of the Heisenberg XXZ ferromagnet. The three-dimensional case of the melting crystal corner is described in terms of a system of coupled XXZ spin chains. We give a conjecture for its mass gap and analyze the system numerically.

  2. Neutron Transmission through Sapphire Crystals

    DEFF Research Database (Denmark)

    Sapphire crystals are excellent filters of fast neutrons, while at the same time exhibit moderate to very little absorption at smaller energies. We have performed an extensive series of measurements in order to quantify the above effect. Alongside our experiments, we have performed a series of...... simulations, in order to reproduce the transmission of cold neutrons through sapphire crystals. Those simulations were part of the effort of validating and improving the newly developed interface between the Monte-Carlo neutron transport code MCNP and the Monte Carlo ray-tracing code McStas....

  3. Phononic crystals and acoustic metamaterials

    Directory of Open Access Journals (Sweden)

    Ming-Hui Lu

    2009-12-01

    Full Text Available Phononic crystals have been proposed about two decades ago and some important characteristics such as acoustic band structure and negative refraction have stimulated fundamental and practical studies in acoustic materials and devices since then. To carefully engineer a phononic crystal in an acoustic “atom” scale, acoustic metamaterials with their inherent deep subwavelength nature have triggered more exciting investigations on negative bulk modulus and/or negative mass density. Acoustic surface evanescent waves have also been recognized to play key roles to reach acoustic subwavelength imaging and enhanced transmission.

  4. Quantum computation in photonic crystals

    CERN Document Server

    Angelakis, D G; Yannopapas, V; Ekert, A; Angelakis, Dimitris G.; Santos, Marcelo Franca; Yannopapas, Vassilis; Ekert, Artur

    2004-01-01

    Quantum computers require technologies that offer both sufficient control over coherent quantum phenomena and minimal spurious interactions with the environment. We show, that photons confined to photonic crystals, and in particular to highly efficient waveguides formed from linear chains of defects doped with atoms can generate strong non-linear interactions which allow to implement both single and two qubit quantum gates. The simplicity of the gate switching mechanism, the experimental feasibility of fabricating two dimensional photonic crystal structures and integrability of this device with optoelectronics offers new interesting possibilities for optical quantum information processing networks.

  5. Acoustooptic Diffraction in Borate Crystals

    CERN Document Server

    Martynyuk-Lototska, I; Krupych, O; Adamiv, V; Smirnov, Ye; Vlokh, R

    2004-01-01

    The efficiency of acoustooptic (AO) diffraction in a-BaB2O4 and Li2B4O7 crystals is studied experimentally. The crystals are shown to be quite good AO materials. The efficiency of AO diffraction in a-BaB2O4 reaches h=30% at the electric signal power of P=0.7W for the transverse acoustic wave and 15% at the power of P=0.56W for the longitudinal wave. The same parameter for Li2B4O7 reaches h=21% at P=0,81W for the longitudinal acoustic wave.

  6. Nanoscale characterisation of crystal zoning

    OpenAIRE

    Saunders, Kate; Buse, Ben; Kilburn, Matt; Kearns, Stuart; Blundy, Jon

    2014-01-01

    Advances in analytical techniques are fundamental to the enhanced understandings of many geological processes. Zoned volcanic crystals have been analysed by low (5) kV field emission gun electron probe micro-analyser (FEG-EPMA) and NanoSIMS to obtain sub-micrometre chemical profiles and compared to time-of-flight SIMS (TOF-SIMS) and high (15–20) kV EPMA profiles. Plagioclase and orthopyroxene crystals have been analysed by FEG-EPMA, at accelerating voltages of 5 kV providing a spatial resolut...

  7. X-ray crystal interferometers

    International Nuclear Information System (INIS)

    Various configurations of the X-ray crystal interferometer are reviewed. The interferometer applications considered include metrology, the measurement of fundamental physical constants, the study of weakly absorbing phase objects, time-resolved diagnostics, the determination of hard X-ray beam parameters, and the characterization of structural defects in the context of developing an X-ray Michelson interferometer. The three-crystal Laue interferometer (LLL-interferometer), its design, and the experimental opportunities it offers are given particular attention. (instruments and methods of investigation)

  8. Manufacturing method of photonic crystal

    Science.gov (United States)

    Park, In Sung; Lee, Tae Ho; Ahn, Jin Ho; Biswas, Rana; Constant, Kristen P.; Ho, Kai-Ming; Lee, Jae-Hwang

    2013-01-29

    A manufacturing method of a photonic crystal is provided. In the method, a high-refractive-index material is conformally deposited on an exposed portion of a periodic template composed of a low-refractive-index material by an atomic layer deposition process so that a difference in refractive indices or dielectric constants between the template and adjacent air becomes greater, which makes it possible to form a three-dimensional photonic crystal having a superior photonic bandgap. Herein, the three-dimensional structure may be prepared by a layer-by-layer method.

  9. Crystal Bases and Young Tableaux

    OpenAIRE

    Cliff, Gerald

    1997-01-01

    Let B be the crystal basis of the minus part of the quantized enveloping algebra of a semi-simple Lie algebra. Kashiwara has shown that B has a combinatorial description in terms of an embedding of B into the tensor product of B and k abstract crystals B_{i_j}, j=1,2,...,k, where the longest word in the Weyl group is s_{i_1}...s_{i_k}. We give an explicit description of the image of this embedding for classical Lie algebras of types A, B, C, D. This description is in terms of semi-standard Yo...

  10. Crystal structures of cristobalite-type and coesite-type PON redetermined on the basis of single-crystal X-ray diffraction data.

    Science.gov (United States)

    Bykov, Maxim; Bykova, Elena; Dyadkin, Vadim; Baumann, Dominik; Schnick, Wolfgang; Dubrovinsky, Leonid; Dubrovinskaia, Natalia

    2015-11-01

    Hitherto, phospho-rus oxonitride (PON) could not be obtained in the form of single crystals and only powder diffraction experiments were feasible for structure studies. In the present work we have synthesized two polymorphs of phospho-rus oxonitride, cristobalite-type (cri-PON) and coesite-type (coe-PON), in the form of single crystals and reinvestigated their crystal structures by means of in house and synchrotron single-crystal X-ray diffraction. The crystal structures of cri-PON and coe-PON are built from PO2N2 tetra-hedral units, each with a statistical distribution of oxygen and nitro-gen atoms. The crystal structure of the coe-PON phase has the space group C2/c with seven atomic sites in the asymmetric unit [two P and three (N,O) sites on general positions, one (N,O) site on an inversion centre and one (N,O) site on a twofold rotation axis], while the cri-PON phase possesses tetra-gonal I-42d symmetry with two independent atoms in the asymmetric unit [the P atom on a fourfold inversion axis and the (N,O) site on a twofold rotation axis]. In comparison with previous structure determinations from powder data, all atoms were refined with anisotropic displacement parameters, leading to higher precision in terms of bond lengths and angles. PMID:26594502

  11. Introduction to crystal growth and characterization

    CERN Document Server

    Benz, Klaus-Werner

    2014-01-01

    This new textbook provides for the first time a comprehensive treatment of the basics of contemporary crystallography and crystal growth in a single volume. The reader will be familiarized with the concepts for the description of morphological and structural symmetry of crystals. The architecture of crystal structures of selected inorganic and molecular crystals is illustrated. The main crystallographic databases as data sources of crystal structures are described. Nucleation processes, their kinetics and main growth mechanism will be introduced in fundamentals of crystal growth. Some phase d

  12. Research on colored lyotropic liquid crystals

    Institute of Scientific and Technical Information of China (English)

    WEI Xilian; YIN Baolin; SUN Dezhi; LIU Jie; WANG Zhongni; LI Ganzuo

    2005-01-01

    Splendidly colored lyotropic liquid crystals formed in the ternary system of a novel cationic surfactant, 3-p-nonylphenoxy-2-hydroxypropyl trimethyl ammonium bromide (NPTAB)-n-butanol-water system, had been observed under polarized light microscope. Small-angle X-ray scattering (SAXS), 2H (deuterium) quadrupolar splitting (2H NMR) were employed to confirm the structures of these liquid crystals. The structural transformation of these special lyotropic liquid crystals had been confirmed by differential scanning calorimetry (DSC). The influences of liquid crystal film thickness, temperature and conserving time on the color of liquid crystals have been investigated. It is also theoretically discussed for forming and changing of liquid crystal color.

  13. Field measurements and identification of crystal plasticity models

    International Nuclear Information System (INIS)

    The study deals with experimental aspects and model development for crystal plasticity. The constitutive equations introduce a new interaction matrix, stopping colinear slip, that is validated by means of tests on OFHC copper involving complex loading paths. The strain localisation is analysed thanks to field measurements obtained under scanning electron microscope during complex loading path experiment. A 3D synthetic representative microstructure is developed from EBSD map for a comparison between experimental fields and FE computations. Finally, several mean fields models are numerically evaluated by a comparison with periodic FE computations at a mesoscopic scale and on the level of the phases. The representative volume element is defined at macro and micro scales. (author)

  14. Crystal structure of inactive form of Rab3B

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei [Hubei Key Laboratory of Genetic Regulation and Integrative Biology, College of Life Science, Huazhong Normal University, Wuhan 430079 (China); Shen, Yang [Structural Genomics Consortium, University of Toronto, 101 College St., Toronto, Ontario, Canada M5G 1L7 (Canada); Jiao, Ronghong [Department of Function Inspection, Hebei Provincial People' s Hospital, Shijiazhuang 050051 (China); Liu, Yanli; Deng, Lingfu [Hubei Key Laboratory of Genetic Regulation and Integrative Biology, College of Life Science, Huazhong Normal University, Wuhan 430079 (China); Qi, Chao, E-mail: qichao@mail.ccnu.edu.cn [Hubei Key Laboratory of Genetic Regulation and Integrative Biology, College of Life Science, Huazhong Normal University, Wuhan 430079 (China)

    2012-02-24

    Highlights: Black-Right-Pointing-Pointer This is the first structural information of human Rab3B. Black-Right-Pointing-Pointer To provides a structural basis for the GDP/GTP switch in controlling the activity of Rab3. Black-Right-Pointing-Pointer The charge distribution of Rab3B indicates its unique roles in vesicular trafficking. -- Abstract: Rab proteins are the largest family of ras-related GTPases in eukaryotic cells. They act as directional molecular switches at membrane trafficking, including vesicle budding, cargo sorting, transport, tethering, and fusion. Here, we generated and crystallized the Rab3B:GDP complex. The structure of the complex was solved to 1.9 A resolution and the structural base comparison with other Rab3 members provides a structural basis for the GDP/GTP switch in controlling the activity of small GTPase. The comparison of charge distribution among the members of Rab3 also indicates their different roles in vesicular trafficking.

  15. Crystal structure of inactive form of Rab3B

    International Nuclear Information System (INIS)

    Highlights: ► This is the first structural information of human Rab3B. ► To provides a structural basis for the GDP/GTP switch in controlling the activity of Rab3. ► The charge distribution of Rab3B indicates its unique roles in vesicular trafficking. -- Abstract: Rab proteins are the largest family of ras-related GTPases in eukaryotic cells. They act as directional molecular switches at membrane trafficking, including vesicle budding, cargo sorting, transport, tethering, and fusion. Here, we generated and crystallized the Rab3B:GDP complex. The structure of the complex was solved to 1.9 Å resolution and the structural base comparison with other Rab3 members provides a structural basis for the GDP/GTP switch in controlling the activity of small GTPase. The comparison of charge distribution among the members of Rab3 also indicates their different roles in vesicular trafficking.

  16. Fast response liquid crystal devices

    Science.gov (United States)

    Wu, Yung-Hsun

    Liquid crystal (LC) has been widely used for displays, spatial light modulators, variable optical attenuators (VOAs) and other tunable photonic devices. The response time of these devices is mainly determined by the employed liquid crystal material. The response time of a LC device depends on the visco-elastic coefficient (gamma1/K11), LC cell gap (d), and applied voltage. Hence, low visco-elastic coefficient LC materials and thinner cell gap are favorable for reducing the response time. However, low visco-elastic coefficient LCs are usually associated with a low birefringence because of shorter molecular conjugation. For display applications, such as LCD TVs, low birefringence (Deltanthick cell gap which, in turn, increases the response time. How to obtain fast response for the LC devices is a fundamentally important and technically challenging task. In this dissertation, we investigate several methods to improve liquid crystal response time, for examples, using dual-frequency liquid crystals, polymer stabilized liquid crystals, and sheared polymer network liquid crystals. We discover a new class of material, denoted as sheared polymer network liquid crystal (SPNLC) which exhibits a submillisecond response time. Moreover, this response time is insensitive to the LC cell gap. This is the first LC device exhibiting such an interesting property. Chapters 1 and 2 describe the motivation and background of this dissertation. From chapter 3 to chapter 6, dual-frequency liquid crystals and polymer network methods are demonstrated as examples for the variable optical attenuators. Variable optical attenuator (VOA) is a key component in optical communications. Especially, the sheared PNLC VOA shows the best result; its dynamic range reaches 43 dB while the response time is in the submillisecond range at 1550 nm wavelength, which is 50 times faster than the commercial LC-based VOA. In Chapter 7, we report a new device called axially-symmetric sheared polymer network liquid

  17. Aluminum-induced oxidative stress and neurotoxicity in grass carp (Cyprinidae--Ctenopharingodon idella).

    Science.gov (United States)

    Fernández-Dávila, María Lourdes; Razo-Estrada, Amparo Celene; García-Medina, Sandra; Gómez-Oliván, Leobardo Manuel; Piñón-López, Manuel Jesús; Ibarra, Rocio Guzmán; Galar-Martínez, Marcela

    2012-02-01

    Aluminum is used in a large number of anthropogenic processes, leading to aquatic ecosystems pollution. Diverse studies show that in mammals this metal may produce oxidative stress, is neurotoxic, and is involved in the development of neurodegenerative disorders, such as Alzhaimer's and Parkinson's diseases. Nevertheless, there are only few studies with respect to Al-induced neurotoxicity on aquatic fauna, particularly on fishes of economical interest, such as the grass carp (Ctenopharingodon idella). This study evaluates Al-induced toxicity on the grass carp C. idella. Specimens were exposed to the maximum concentration allowed in order to protect aquatic life (0.1 mg L⁻¹), for 12, 24, 48, 72 and 96 h. After the exposure time, lipid peroxidation degree, superoxide dismutase and catalase activity, as well as dopamine, adrenaline and noradrenaline levels were evaluated. Al concentration in organisms and water was also measured, in order to determine the bioconcentration factor. Results show that Al bioconcentrates in grass carp inducing oxidative stress (increment of 300 and 455 percent on lipid peroxidation degree and SOD activity, and decrement of 49 percent on CAT activity) and neurotoxicity (increment of 55 and 155 percent on dopamine and adrenaline levels and decrement of 93 percent on noradrenaline level). PMID:21993346

  18. An Aluminum-Inducible IREG Gene is Required for Internal Detoxification of Aluminum in Buckwheat.

    Science.gov (United States)

    Yokosho, Kengo; Yamaji, Naoki; Mitani-Ueno, Namiki; Shen, Ren Fang; Ma, Jian Feng

    2016-06-01

    Buckwheat (Fagopyrum esculentum Moench) is able to detoxify aluminum (Al) both externally and internally, but the molecular mechanisms underlying its high Al tolerance are not understood. We functionally characterized a gene (FeIREG1) belonging to IRON REGULATED/ferroportin in buckwheat, which showed high expression in our previous genome-wide transcriptome analysis. FeIREG1 was mainly expressed in the roots, and its expression was up-regulated by Al, but not by other metals and low pH. Furthermore, in contrast to AtIREG1 and AtIREG2 in Arabidopsis, the expression of FeIREG1 was not induced by Fe deficiency. Spatial expression analysis showed that the Al-induced expression of FeIREG1 was found in the root tips and higher expression was detected in the outer layers of this part. Immunostaining also showed that FeIREG1 was localized at the outer cell layers in the root tip. A FeIREG1-green fluorescent protein (GFP) fusion protein was localized to the tonoplast when transiently expressed in onion epidermal cells. Overexpression of FeIREG1 in Arabidopsis resulted in increased Al tolerance, but did not alter the tolerance to Cd, Co and Fe. The tolerance to Ni was slightly enhanced in the overexpression lines. Mineral analysis showed that the accumulation of total root Al and other essential mineral elements was hardly altered in the overexpression lines. Taken together, our results suggest that FeIREG1 localized at the tonoplast plays an important role in internal Al detoxification by sequestering Al into the root vacuoles in buckwheat. PMID:27053033

  19. Aluminum-Induced Entropy in Biological Systems: Implications for Neurological Disease

    Directory of Open Access Journals (Sweden)

    Christopher A. Shaw

    2014-01-01

    Full Text Available Over the last 200 years, mining, smelting, and refining of aluminum (Al in various forms have increasingly exposed living species to this naturally abundant metal. Because of its prevalence in the earth’s crust, prior to its recent uses it was regarded as inert and therefore harmless. However, Al is invariably toxic to living systems and has no known beneficial role in any biological systems. Humans are increasingly exposed to Al from food, water, medicinals, vaccines, and cosmetics, as well as from industrial occupational exposure. Al disrupts biological self-ordering, energy transduction, and signaling systems, thus increasing biosemiotic entropy. Beginning with the biophysics of water, disruption progresses through the macromolecules that are crucial to living processes (DNAs, RNAs, proteoglycans, and proteins. It injures cells, circuits, and subsystems and can cause catastrophic failures ending in death. Al forms toxic complexes with other elements, such as fluorine, and interacts negatively with mercury, lead, and glyphosate. Al negatively impacts the central nervous system in all species that have been studied, including humans. Because of the global impacts of Al on water dynamics and biosemiotic systems, CNS disorders in humans are sensitive indicators of the Al toxicants to which we are being exposed.

  20. Investigation of the pitting of aluminum induced by chloride ions by holographic microphotography

    Directory of Open Access Journals (Sweden)

    LIANG LI

    2008-05-01

    Full Text Available Holographic microphotography was used to investigate the dynamic processes of pitting during anodic dissolution of aluminum in a solution containing chloride ions. The induction and the follow-up propagation processes of the pitting were observed in real-time. A simple model of the propagating process of the pitting was deduced from the result of the holograms of the Al/electrolyte interface. The results prove that holographic microphotography is a useful tool to study the dynamic processes of pitting.