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Sample records for liquid crystal point-diffraction

New structural studies of liquid crystal by reflectivity and resonant X-ray diffraction

International Nuclear Information System (INIS)

Fernandes, P.

2007-04-01

This memory presents three structural studies of smectic Liquid Crystals by reflectivity and resonant diffraction of X-rays. It is divided in five chapters. In the first a short introduction to Liquid Crystals is given. In particular, the smectic phases that are the object of this study are presented. The second chapter is consecrated to the X-ray experimental techniques that were used in this work. The three last chapters present the works on which this thesis can be divided. Chapter three demonstrates on free-standing films of MHPOBC (historic liquid crystal that possesses the antiferroelectric sub-phases) the possibility to extend the technique of resonant X-ray diffraction to liquid crystals without resonant element. In the fourth chapter the structure of the B 2 liquid crystal phase of bent-core molecules (or banana molecules) is elucidated by using resonant X-ray diffraction combined with polarization analysis of the diffracted beam. A model of the polarization of the resonant beam diffracted by four different structures proposed for the B 2 phase is developed in this chapter. In the fifth chapter a smectic binary mixture presenting a very original critical point of phase separation is studied by X-ray reflectivity and optical microscopy. A concentration gradient in the direction perpendicular to the plane of the film seems to be induced by the free-standing film geometry. The results of a simplified model of the system are compatible with this interpretation
New structural studies of liquid crystal by reflectivity and resonant X-ray diffraction; Nouvelles etudes structurales de cristaux liquides par reflectivite et diffraction resonante des rayons X

Energy Technology Data Exchange (ETDEWEB)

Fernandes, P

2007-04-15

This memory presents three structural studies of smectic Liquid Crystals by reflectivity and resonant diffraction of X-rays. It is divided in five chapters. In the first a short introduction to Liquid Crystals is given. In particular, the smectic phases that are the object of this study are presented. The second chapter is consecrated to the X-ray experimental techniques that were used in this work. The three last chapters present the works on which this thesis can be divided. Chapter three demonstrates on free-standing films of MHPOBC (historic liquid crystal that possesses the antiferroelectric sub-phases) the possibility to extend the technique of resonant X-ray diffraction to liquid crystals without resonant element. In the fourth chapter the structure of the B{sub 2} liquid crystal phase of bent-core molecules (or banana molecules) is elucidated by using resonant X-ray diffraction combined with polarization analysis of the diffracted beam. A model of the polarization of the resonant beam diffracted by four different structures proposed for the B{sub 2} phase is developed in this chapter. In the fifth chapter a smectic binary mixture presenting a very original critical point of phase separation is studied by X-ray reflectivity and optical microscopy. A concentration gradient in the direction perpendicular to the plane of the film seems to be induced by the free-standing film geometry. The results of a simplified model of the system are compatible with this interpretation.
Diffraction and signal processing experiments with a liquid crystal microdisplay

International Nuclear Information System (INIS)

MartInez, Jose Luis; Moreno, Ignacio; Ahouzi, Esmail

2006-01-01

In this work, we show some diffraction experiments performed with a liquid crystal display (LCD) that shows how useful this device can be to teach and experience diffraction optics and signal processing experiments. The LCD acts as a programmable pixelated diffractive mask. The Fourier spectrum of the image displayed in the LCD is visualized through a simple free propagation diffraction experiment. This optical system allows easy testing of different diffractive elements. As a demonstration we include experimental results with well-known diffractive elements like diffraction gratings or Fresnel lenses, and with more complicated elements like computer-generated holograms
Diffraction and signal processing experiments with a liquid crystal microdisplay

Energy Technology Data Exchange (ETDEWEB)

MartInez, Jose Luis [Departamento de Ciencia y TecnologIa de Materiales, Universidad Miguel Hernandez de Elche, Alicante (Spain); Moreno, Ignacio [Departamento de Ciencia y TecnologIa de Materiales, Universidad Miguel Hernandez de Elche, Alicante (Spain); Ahouzi, Esmail [Institut National des Postes et Telecomunications (INTP), Madinat Al Irfane, Rabat (Morocco)

2006-09-01

In this work, we show some diffraction experiments performed with a liquid crystal display (LCD) that shows how useful this device can be to teach and experience diffraction optics and signal processing experiments. The LCD acts as a programmable pixelated diffractive mask. The Fourier spectrum of the image displayed in the LCD is visualized through a simple free propagation diffraction experiment. This optical system allows easy testing of different diffractive elements. As a demonstration we include experimental results with well-known diffractive elements like diffraction gratings or Fresnel lenses, and with more complicated elements like computer-generated holograms.
Local layer structure of smectic liquid crystals by X-ray micro-diffraction

CERN Document Server

Takanishi, Y

2003-01-01

The local layer structure of smectic liquid crystal has been measured using time-resolved synchrotron X-ray micro-diffraction. Typical layer disorders observed in surface stabilized (anti-) ferroelectric liquid crystals, i.e. a stripe texture, a needed-like defect and a zigzag defect, are directly analyzed. The detailed analysis slows that the surface anchoring force due to the interaction between the liquid crystal molecule and the alignment thin film plays an important role to realize both the static and dynamic local layer structures. The layer structure of the circular domain observed in the liquid crystal of bent-shaped molecules found to depend on the applied electric field though the optical micrograph shows little difference. The frustrated, double and single layer structures of the bent-shaped molecule liquid crystal are determined depending on the terminal alkyl chain length. (author)
Tunable diffraction and self-defocusing in liquid-filled photonic crystal fibers

DEFF Research Database (Denmark)

Rosberg, Christian Romer; Bennet, Francis H.; Neshev, Dragomir N.

2007-01-01

We suggest and demonstrate a novel platform for the study of tunable nonlinear light propagation in two-dimensional discrete systems, based on photonic crystal fibers filled with high index nonlinear liquids. Using the infiltrated cladding region of a photonic crystal fiber as a nonlinear waveguide...... array, we experimentally demonstrate highly tunable beam diffraction and thermal self-defocusing, and realize a compact all-optical power limiter based on a tunable nonlinear response....
Blazed vector gratings fabricated using photosensitive polymer liquid crystals and control of polarization diffraction

Science.gov (United States)

Ono, Hiroshi; Kuzuwata, Mitsuru; Sasaki, Tomoyuki; Noda, Kohei; Kawatsuki, Nobuhiro

2014-03-01

The blazed vector grating possessing antisymmetric distributions of the birefringence were fabricated by exposing the line-focused linearly polarized ultraviolet light on the photosensitive polymer liquid crystals. The polarization states of the diffraction beams can be highly and widely controlled by designing the blazed structures, and the diffraction properties were well-explained by Jones calculus.
Synchrotron x-ray diffraction study of liquid surfaces

DEFF Research Database (Denmark)

Als-Nielsen, Jens Aage; Pershan, P.S.

1983-01-01

A spectrometer for X-ray diffraction and refraction studies of horizontal, free surfaces of liquids is described. As an illustration smetic-A layering at the surface of a liquid crystal is presented.......A spectrometer for X-ray diffraction and refraction studies of horizontal, free surfaces of liquids is described. As an illustration smetic-A layering at the surface of a liquid crystal is presented....
Near-diffraction-limited and low-haze electro-optical tunable liquid crystal lens with floating electrodes.

Science.gov (United States)

Li, Liwei; Bryant, Doug; Van Heugten, Tony; Bos, Philip J

2013-04-08

A near-diffraction-limited, low-haze and tunable liquid crystal (LC) lens is presented. Building on an understanding of the key factors that have limited the performance of lenses based on liquid crystals, we show a simple design whose optical quality is similar to a high quality glass lens. It uses 'floating' electrodes to provide a smooth, controllable applied potential profile across the aperture to manage the phase profile.
Flat liquid crystal diffractive lenses with variable focus and magnification

Science.gov (United States)

Valley, Pouria

Non-mechanical variable lenses are important for creating compact imaging devices. Various methods employing dielectrically actuated lenses, membrane lenses, and liquid crystal lenses were previously proposed [1-4]. In This dissertation the design, fabrication, and characterization of innovative flat tunable-focus liquid crystal diffractive lenses (LCDL) are presented. LCDL employ binary Fresnel zone electrodes fabricated on Indium-Tin-Oxide using conventional micro-photolithography. The light phase can be adjusted by varying the effective refractive index of a nematic liquid crystal sandwiched between the electrodes and a reference substrate. Using a proper voltage distribution across various electrodes the focal length can be changed between several discrete values. Electrodes are shunted such that the correct phase retardation step sequence is achieved. If the number of 2pi zone boundaries is increased by a factor of m the focal length is changed from f to f/m based on the digitized Fresnel zone equation: f = rm2/2mlambda, where r m is mth zone radius, and lambda is the wavelength. The chromatic aberration of the diffractive lens is addressed and corrected by adding a variable fluidic lens. These LCDL operate at very low voltage levels (+/-2.5V ac input), exhibit fast switching times (20-150 ms), can have large apertures (>10 mm), and small form factor, and are robust and insensitive to vibrations, gravity, and capillary effects that limit membrane and dielectrically actuated lenses. Several tests were performed on the LCDL including diffraction efficiency measurement, switching dynamics, and hybrid imaging with a refractive lens. Negative focal lengths are achieved by adjusting the voltages across electrodes. Using these lenses in combination, magnification can be changed and zoom lenses can be formed. These characteristics make LCDL a good candidate for a variety of applications including auto-focus and zoom lenses in compact imaging devices such as camera
Strong dielectric liquid crystal polymer (Part 3)

Energy Technology Data Exchange (ETDEWEB)

Kurata, Hideaki; Shibasaki, Akira

1988-11-01

Influence of change of molecular parameters on liquid crystal condition is studied to get the correlation between molecular structure of liquid crystal and phase structure or visco-elastic properties. Eight kinds of biphenyl type liquid crystals with polyacrilate main chain and triphenyl type liquid crystals were used as samples. Followings were found by a ploarizing microscope and X-ray diffraction: Phases are transferred from isotropic phase S/sub A/ phase S/sup *//sub C/ phase S/sub 1/ phase to solid on temperature desending sequence. Degree of polymerization changes only these transfer point but spacer length affects not only transfer points and layer distance but also liquid crystal structure itself. Visco-elasticity of isotropic phase shows Newtonian viscosity and is affected by the main chain length. Macroscopic and microscopic structures influence on viscoelasticity in S/sub A/ phase and S/sup *//sub C/ phase. Two rapid rises of viscoelasticity are found in low molecular weight liquid crystal when S/sub A/ transfer and S/sub A/ to S/sup *//sub C/ transfer occur by temperature desending from the isotropic phase. Viscoelastic behavior is contributed by the properties of domain itself and interaction between domains, and the interaction is changed by polymerization. 6 references, 13 figures, 1 table.
Liquid gallium cooling of silicon crystals in high intensity photon beam

International Nuclear Information System (INIS)

Smither, R.K.; Forster, G.A.; Bilderback, D.H.

1988-11-01

The high-brilliance, insertion-device-based, photon beams of the next generation of synchrotron sources will deliver large thermal loads (1 kW to 10 kW) to the first optical elements. Considering the problems that present synchrotron users are experiencing with beams from recently installed insertion devices, new and improved methods of cooling these first optical elements, particularly when they are diffraction crystals, are clearly needed. A series of finite element calculations were performed to test the efficiency of new cooling geometries and new cooling fluids. The best results were obtained with liquid Ga metal flowing in channels just below the surface of the crystal. Ga was selected because of its good thermal conductivity and thermal capacity, low melting point, high boiling point, low kinetic viscosity, and very low vapor pressure. Its very low vapor pressure, even at elevated temperatures, makes it especially attractive in uhv conditions. A series of experiments were conducted at CHESS in February of 1988 that compared liquid gallium cooled silicon diffraction crystals with water cooled crystals. 2 refs., 16 figs., 1 tab
Study of self-diffraction phenomenon in hybrid liquid crystal panel

International Nuclear Information System (INIS)

Sznitko, L; Bartkiewicz, S; Anczykowska, A; Mysliwiec, J

2009-01-01

In this paper we present the results of dynamics of hologram generation in hybrid nematic liquid crystal panels with photoconducting layers (made of poly-N-vinyl-carbazole doped with 2,4,7-tri-nitrofluorenone) for different applied voltages. During experiments we have measured the temporal changes in the diffraction efficiency coefficient. To reach the equilibrium between all writing processes we have used the 'long pulse method' to generate holograms. This method exhibited the insufficiency of earlier presented refractive index time dependence and a new model had to be proposed. We assumed the existence of charge traps in photoconducting layers which results in additional erasing functions in particular refractive index time dependence. Comparison of the newly proposed mathematical model and the experimental results has shown very good agreement.
Study of self-diffraction phenomenon in hybrid liquid crystal panel

Energy Technology Data Exchange (ETDEWEB)

Sznitko, L; Bartkiewicz, S; Anczykowska, A; Mysliwiec, J, E-mail: jaroslaw.mysliwiec@pwr.wroc.p [Institute of Physical and Theoretical Chemistry, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland)

2009-10-21

In this paper we present the results of dynamics of hologram generation in hybrid nematic liquid crystal panels with photoconducting layers (made of poly-N-vinyl-carbazole doped with 2,4,7-tri-nitrofluorenone) for different applied voltages. During experiments we have measured the temporal changes in the diffraction efficiency coefficient. To reach the equilibrium between all writing processes we have used the 'long pulse method' to generate holograms. This method exhibited the insufficiency of earlier presented refractive index time dependence and a new model had to be proposed. We assumed the existence of charge traps in photoconducting layers which results in additional erasing functions in particular refractive index time dependence. Comparison of the newly proposed mathematical model and the experimental results has shown very good agreement.
Time-Resolved Soft X-ray Diffraction Reveals Transient Structural Distortions of Ternary Liquid Crystals

Directory of Open Access Journals (Sweden)

Klaus Mann

2009-11-01

Full Text Available Home-based soft X-ray time-resolved scattering experiments with nanosecond time resolution (10 ns and nanometer spatial resolution were carried out at a table top soft X-ray plasma source (2.2–5.2 nm. The investigated system was the lyotropic liquid crystal C16E7/paraffin/glycerol/formamide/IR 5. Usually, major changes in physical, chemical, and/or optical properties of the sample occur as a result of structural changes and shrinking morphology. Here, these effects occur as a consequence of the energy absorption in the sample upon optical laser excitation in the IR regime. The liquid crystal shows changes in the structural response within few hundred nanoseconds showing a time decay of 182 ns. A decrease of the Bragg peak diffracted intensity of 30% and a coherent macroscopic movement of the Bragg reflection are found as a response to the optical pump. The Bragg reflection movement is established to be isotropic and diffusion controlled (1 μs. Structural processes are analyzed in the Patterson analysis framework of the time-varying diffraction peaks revealing that the inter-lamellar distance increases by 2.7 Å resulting in an elongation of the coherently expanding lamella crystallite. The present studies emphasize the possibility of applying TR-SXRD techniques for studying the mechanical dynamics of nanosystems.
Liquid gallium cooling of silicon crystals in high intensity photon beams

International Nuclear Information System (INIS)

Smither, R.K.; Forster, G.A.; Bilderback, D.H.; Bedzyk, M.; Finkelstein, K.; Henderson, C.; White, J.; Berman, L.E.; Stefan, P.; Oversluizen, T.

1989-01-01

The high-brilliance, insertion-device-based photon beams of the next generation of synchrotron sources (Argonne's APS and Grenoble's ESRF) will deliver large thermal loads (1--10 kW) to the first optical elements. Considering the problems that present synchrotron users are experiencing with beams from recently installed insertion devices, new and improved methods of cooling these first optical elements, particularly when they are diffraction crystals, are clearly needed. A series of finite element calculations were performed to test the efficiency of new cooling geometries and various cooling fluids. The best results were obtained with liquid Ga metal flowing in channels just below the surface of the crystal. Ga was selected because of its good thermal conductivity and thermal capacity, low melting point, high boiling point, low kinetic viscosity, and very low vapor pressure. Its very low vapor pressure, even at elevated temperatures, makes it especially attractive in UHV conditions. A series of experiments were conducted at CHESS in February of 1988 that compared liquid gallium-cooled silicon diffraction crystals with water-cooled crystals. A six-pole wiggler beam was used to perform these tests on three different Si crystals, two with new cooling geometries and the one presently in use. A special high-pressure electromagnetic induction pump, recently developed at Argonne, was used to circulate the liquid gallium through the silicon crystals. In all experiments, the specially cooled crystal was used as the first crystal in a two crystal monochromator. An infrared camera was used to monitor the thermal profiles and correlated them with rocking curve measurements. A second set of cooling experiments were conducted in June of 1988 that used the intense, highly collimated beam from the newly installed ANL/CHESS undulator
Ray tracing through the liquid crystal point diffraction interferometer. 1998 summer research program for high school juniors at the University of Rochester's Laboratory for Laser Energetics. Student research reports

International Nuclear Information System (INIS)

Turner, A.

1999-03-01

The Omega laser is a system with many different parts that may cause imperfections. There are a multitude of lenses and mirrors, for example, that may not be polished correctly and can cause the laser wave front to have aberrations. The Liquid Crystal Point Diffraction Interferometer (L.C.P.D.I.) is a device whose main purpose is to read the wave front of the laser and measure any aberrations that may be on it. The way the L.C.P.D.I. reads the laser wave front and measures these aberrations is very complicated and has yet to be perfected. A ray-tracing model of the L.C.P.D.I. has been built, which calculates and models the ray trajectories, the optical paths of the rays, the O.P.D. between the object and reference beams, the absorption of the rays in the liquid crystal, and the intensities of each beam. It can predict an actual experiment by manipulating the different parameters of the program. It will be useful in optimization and further development of the L.C.P.D.I. Evidently, it is necessary to develop a liquid crystal solution with an O.D. greater than 0.3, and possibly as high as 2.0. This new solution would be able to reduce the intensity of the object beam sufficiently to make it comparable with the reference beam intensity. If this were achieved, the contrast, or visibility of the fringes would be better, and the interferogram could be used to diagnose the aberrations in the laser beam front. Then the cause of the aberrations could be fixed. This would result in a near-perfect laser front. If this were achieved, then it is possible that laser fusion could be made more efficient and possibly used as an energy source
Micro-Holograms in a Methyl Red-Doped Polymer-Dispersed Liquid Crystal (E48:PVP

Directory of Open Access Journals (Sweden)

N. P. Hermosa II

2003-06-01

Full Text Available Feasibility of a holographic point-by-point storage in a methyl red-doped Polymer-Dispersed LiquidCrystal (PDLC is determined. Micro-holograms (gratings are recorded next to each other. Smallestgrating diameter obtained is 69.9 mm, with minimum grating distance of 80 mm. Recording of adjacentgrating reduces the diffraction efficiency of existing grating by 17% (average.
Liquid-metal-cooled, curved-crystal monochromator for Advanced Photon Source bending-magnet beamline 1-BM

International Nuclear Information System (INIS)

Brauer, S.; Rodricks, B.; Assoufid, L.; Beno, M.A.; Knapp, G.S.

1996-06-01

The authors describe a horizontally focusing curved-crystal monochromator that invokes a 4-point bending scheme and a liquid-metal cooling bath. The device has been designed for dispersive diffraction and spectroscopy in the 5--20 keV range, with a predicted focal spot size of ≤ 100 microm. To minimize thermal distortions and thermal equilibration time, the 355 x 32 x 0.8 mm crystal will be nearly half submerged in a bath of Ga-In-Sn-Zn alloy. The liquid metal thermally couples the crystal to the water-cooled Cu frame, while permitting the required crystal bending. Calculated thermal profiles and anticipated focusing properties are discussed
Holographic Formation of Diffraction Elements for Transformation of Light Beams in Liquid Crystal - Photopolymer Compositions

Science.gov (United States)

Semkin, A. O.; Sharangovich, S. N.

2018-03-01

A theoretical model of holographic formation of diffractive optical elements for transformation of light beam field into Bessel-like fields in liquid crystal - photopolymer (LC-PPM) composite materials with a dyesensitizer is developed. Results of numerical modeling of kinetics ofvariation of the refractive index of a material in the process of formation with different relationships between the photopolymerization rates and diffusion processes are presented. Based on the results of numerical simulation, it is demonstrated that when the photopolarization process dominates, the diffractive element being formed is distorted. This leads to a change in the light field distribution at its output and consequently, to ineffective transformation of the reading beam. Thus, the necessity of optimizing of the recording conditions and of the prepolymeric composition to increase the transformation efficiency of light beam fields is demonstrated.

Phase-Shifting Liquid Crystal Interferometers for Microgravity Fluid Physics

Science.gov (United States)

Griffin, DeVon W.; Marshall, Keneth L.

2002-01-01

The initial focus of this project was to eliminate both of these problems in the Liquid Crystal Point-Diffraction Interferometer (LCPDI). Progress toward that goal will be described, along with the demonstration of a phase shifting Liquid Crystal Shearing Interferometer (LCSI) that was developed as part of this work. The latest LCPDI, other than a lens to focus the light from a test section onto a diffracting microsphere within the interferometer and a collimated laser for illumination, the pink region contained within the glass plates on the rod-mounted platform is the complete interferometer. The total width is approximately 1.5 inches with 0.25 inches on each side for bonding the electrical leads. It is 1 inch high and there are only four diffracting microspheres within the interferometer. As a result, it is very easy to align, achieving the first goal. The liquid crystal electro-optical response time is a function of layer thickness, with thinner devices switching faster due to a reduction in long-range viscoelastic forces between the LC molecules. The LCPDI has a liquid crystal layer thickness of 10 microns, which is controlled by plastic or glass microspheres embedded in epoxy 'pads' at the corners of the device. The diffracting spheres are composed of polystyrene/divinyl benzene polymer with an initial diameter of 15 microns. The spheres deform slightly when the interferometer is assembled to conform to the spacing produced by the microsphere-filled epoxy spacer pads. While the speed of this interferometer has not yet been tested, previous LCPDIs fabricated at the Laboratory for Laser Energetics switched at a rate of approximately 3.3 Hz, a factor of 10 slower than desired. We anticipate better performance when the speed of these interferometers is tested since they are approximately three times thinner. Phase shifting in these devices is a function of the AC voltage level applied to the liquid crystal. As the voltage increases, the dye in the liquid crystal
Photonics of liquid-crystal structures: A review

Energy Technology Data Exchange (ETDEWEB)

Palto, S. P., E-mail: palto@online.ru; Blinov, L M; Barnik, M I; Lazarev, V V; Umanskii, B A; Shtykov, N M [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

2011-07-15

The original results of studies of the electro-optical and laser effects which have been performed at the Laboratory of Liquid Crystals of the Institute of Crystallography, Russian Academy of Sciences, over the last few years are reviewed. Cholesteric liquid crystals as vivid representatives of photonic structures and their behavior in an electric field are considered in detail. The formation of higher harmonics in the periodic distribution of the director field in a helical liquid crystal structure and, correspondingly, the new (anharmonic) mode of electro-optical effects are discussed. Another group of studies is devoted to bistable light switching by an electric field in chiral nematics. Polarization diffraction gratings controlled by an electric field are also considered. The results of studies devoted to microlasers on various photonic structures with cholesteric and nematic liquid crystals are considered in detail. Particular attention is given to the new regime: leaky-mode lasing. Designs of liquid crystal light amplifiers and their polarization, field, and spectral characteristics are considered in the last section.
A roadmap to uranium ionic liquids: anti-crystal engineering.

Science.gov (United States)

Yaprak, Damla; Spielberg, Eike T; Bäcker, Tobias; Richter, Mark; Mallick, Bert; Klein, Axel; Mudring, Anja-Verena

2014-05-19

In the search for uranium-based ionic liquids, tris(N,N-dialkyldithiocarbamato)uranylates have been synthesized as salts of the 1-butyl-3-methylimidazolium (C4mim) cation. As dithiocarbamate ligands binding to the UO2(2+) unit, tetra-, penta-, hexa-, and heptamethylenedithiocarbamates, N,N-diethyldithiocarbamate, N-methyl-N-propyldithiocarbamate, N-ethyl-N-propyldithiocarbamate, and N-methyl-N-butyldithiocarbamate have been explored. X-ray single-crystal diffraction allowed unambiguous structural characterization of all compounds except N-methyl-N-butyldithiocarbamate, which is obtained as a glassy material only. In addition, powder X-ray diffraction as well as vibrational and UV/Vis spectroscopy, supported by computational methods, were used to characterize the products. Differential scanning calorimetry was employed to investigate the phase-transition behavior depending on the N,N-dialkyldithiocarbamato ligand with the aim to establish structure-property relationships regarding the ionic liquid formation capability. Compounds with the least symmetric N,N-dialkyldithiocarbamato ligand and hence the least symmetric anions, tris(N-methyl-N-propyldithiocarbamato)uranylate, tris(N-ethyl-N-propyldithiocarbamato)uranylate, and tris(N-methyl-N-butyldithiocarbamato)uranylate, lead to the formation of (room-temperature) ionic liquids, which confirms that low-symmetry ions are indeed suitable to suppress crystallization. These materials combine low melting points, stable complex formation, and hydrophobicity and are therefore excellent candidates for nuclear fuel purification and recovery. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Beam-splitter switches based on zenithal bistable liquid-crystal gratings.

Science.gov (United States)

Zografopoulos, Dimitrios C; Beccherelli, Romeo; Kriezis, Emmanouil E

2014-10-01

The tunable optical diffractive properties of zenithal bistable nematic liquid-crystal gratings are theoretically investigated. The liquid-crystal orientation is rigorously solved via a tensorial formulation of the Landau-de Gennes theory and the optical transmission properties of the gratings are investigated via full-wave finite-element frequency-domain simulations. It is demonstrated that by proper design the two stable states of the grating can provide nondiffracting and diffracting operation, the latter with equal power splitting among different diffraction orders. An electro-optic switching mechanism, based on dual-frequency nematic materials, and its temporal dynamics are further discussed. Such gratings provide a solution towards tunable beam-steering and beam-splitting components with extremely low power consumption.
Quantization rules for point singularities in superfluid 3He and liquid crystals

International Nuclear Information System (INIS)

Blaha, S.

1976-01-01

It is shown that pointlike singularities can exist in superfluid 3 He. Integer quantum numbers are associated with these singularities. The quantization rules follow from the single valuedness of the order parameter and quantities derived from it. The results are also easily extended to the quantization of point singularities in nematic liquid crystals. The pointlike singularities in 3 He-A are experimentally accessible analogs of the magnetic monopole
Analyzing algorithms for nonlinear and spatially nonuniform phase shifts in the liquid crystal point diffraction interferometer. 1998 summer research program for high school juniors at the University of Rochester's Laboratory for Laser Energetics. Student research reports

International Nuclear Information System (INIS)

Jain, N.

1999-03-01

Phase-shifting interferometry has many advantages, and the phase shifting nature of the Liquid Crystal Point Diffraction Interferometer (LCPDI) promises to provide significant improvement over other current OMEGA wavefront sensors. However, while phase-shifting capabilities improve its accuracy as an interferometer, phase-shifting itself introduces errors. Phase-shifting algorithms are designed to eliminate certain types of phase-shift errors, and it is important to chose an algorithm that is best suited for use with the LCPDI. Using polarization microscopy, the authors have observed a correlation between LC alignment around the microsphere and fringe behavior. After designing a procedure to compare phase-shifting algorithms, they were able to predict the accuracy of two particular algorithms through computer modeling of device-specific phase shift-errors
Synthesis and analysis of nickel dithiolene dyes in a nematic liquid crystal host. 1998 summer research program for high school juniors at the University of Rochester's Laboratory for Laser Energetics. Student research reports

International Nuclear Information System (INIS)

Lippa, I.

1999-03-01

The Liquid Crystal Point Diffraction Interferometer (LCPDI) can be employed to evaluate the Omega Laser system for optimum firing capabilities. This device utilizes a nickel dithiolene infrared absorbing liquid crystal dye dissolved in a liquid crystal host medium (Merck E7). Three nickel dithiolene dyes were characterized for both their solubility in the E7 host and their infrared spectral absorption
A roadmap to uranium ionic liquids: Anti-crystal engineering

Energy Technology Data Exchange (ETDEWEB)

Yaprak, Damla; Spielberg, Eike T.; Baecker, Tobias; Richter, Mark; Mallick, Bert [Inorganic Chemistry III, Ruhr-University Bochum (Germany); Klein, Axel [Institut fuer Anorganische Chemie, Koeln Univ. (Germany); Mudring, Anja-Verena [Inorganic Chemistry III, Ruhr-University Bochum (Germany); Materials Science and Engineering, Iowa State University and Critical Materials Institute, Ames Laboratory, Ames, IA (United States)

2014-05-19

In the search for uranium-based ionic liquids, tris(N,N-dialkyldithiocarbamato)uranylates have been synthesized as salts of the 1-butyl-3-methylimidazolium (C{sub 4}mim) cation. As dithiocarbamate ligands binding to the UO{sub 2}{sup 2+} unit, tetra-, penta-, hexa-, and heptamethylenedithiocarbamates, N,N-diethyldithiocarbamate, N-methyl-N-propyldithiocarbamate, N-ethyl-N-propyldithiocarbamate, and N-methyl-N-butyldithiocarbamate have been explored. X-ray single-crystal diffraction allowed unambiguous structural characterization of all compounds except N-methyl-N-butyldithiocarbamate, which is obtained as a glassy material only. In addition, powder X-ray diffraction as well as vibrational and UV/Vis spectroscopy, supported by computational methods, were used to characterize the products. Differential scanning calorimetry was employed to investigate the phase-transition behavior depending on the N,N-dialkyldithiocarbamato ligand with the aim to establish structure-property relationships regarding the ionic liquid formation capability. Compounds with the least symmetric N,N-dialkyldithiocarbamato ligand and hence the least symmetric anions, tris(N-methyl-N-propyldithiocarbamato)uranylate, tris(N-ethyl-N-propyldithiocarbamato)uranylate, and tris(N-methyl-N-butyldithiocarbamato)uranylate, lead to the formation of (room-temperature) ionic liquids, which confirms that low-symmetry ions are indeed suitable to suppress crystallization. These materials combine low melting points, stable complex formation, and hydrophobicity and are therefore excellent candidates for nuclear fuel purification and recovery. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
A roadmap to uranium ionic liquids: Anti-crystal engineering

International Nuclear Information System (INIS)

Yaprak, Damla; Spielberg, Eike T.; Baecker, Tobias; Richter, Mark; Mallick, Bert; Klein, Axel; Mudring, Anja-Verena

2014-01-01

In the search for uranium-based ionic liquids, tris(N,N-dialkyldithiocarbamato)uranylates have been synthesized as salts of the 1-butyl-3-methylimidazolium (C_4mim) cation. As dithiocarbamate ligands binding to the UO_2"2"+ unit, tetra-, penta-, hexa-, and heptamethylenedithiocarbamates, N,N-diethyldithiocarbamate, N-methyl-N-propyldithiocarbamate, N-ethyl-N-propyldithiocarbamate, and N-methyl-N-butyldithiocarbamate have been explored. X-ray single-crystal diffraction allowed unambiguous structural characterization of all compounds except N-methyl-N-butyldithiocarbamate, which is obtained as a glassy material only. In addition, powder X-ray diffraction as well as vibrational and UV/Vis spectroscopy, supported by computational methods, were used to characterize the products. Differential scanning calorimetry was employed to investigate the phase-transition behavior depending on the N,N-dialkyldithiocarbamato ligand with the aim to establish structure-property relationships regarding the ionic liquid formation capability. Compounds with the least symmetric N,N-dialkyldithiocarbamato ligand and hence the least symmetric anions, tris(N-methyl-N-propyldithiocarbamato)uranylate, tris(N-ethyl-N-propyldithiocarbamato)uranylate, and tris(N-methyl-N-butyldithiocarbamato)uranylate, lead to the formation of (room-temperature) ionic liquids, which confirms that low-symmetry ions are indeed suitable to suppress crystallization. These materials combine low melting points, stable complex formation, and hydrophobicity and are therefore excellent candidates for nuclear fuel purification and recovery. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Anomalous effect of high-frequency ultrasound on radiation diffraction in deformed single crystals

International Nuclear Information System (INIS)

Iolin, E.M.; Rajtman, Eh.A.; Kuvaldin, B.V.; Zolotoyabko, Eh.V.

1988-01-01

Results are presented of a theoretical and experimental study of neutron and X-ray diffraction in defromed single crystals on high-frequency ultrasonic excitation. It is demonstrated theoretically that at a frequency exceeding a certain threshold value the ultrasound violates the adiabatic conditions for the excitation point motion on the dispersion surface branches. This leads to an anomalous (compared to diffraction for a perfect crystal) dependence of the diffraction intensity on the ultrasonic wave amplitude. The experimental data for Si crystals are in good agreement with the theoretical predictions
Molecular reorientation of dye doped nematic liquid crystals in the laser illumination

International Nuclear Information System (INIS)

San, S. E.; Koeysal, O.; Ecevit, F. N.

2002-01-01

In this study it is investigated how dye doped nematic liquid crystals reorient under the illumination of laser beam whose wavelength is appropriate to absorbance characteristics of the doping dye. Nematic liquid crystal E7 is used with anthraquinone dye 1% wt/wt in the preparation of the sample and this material is filled in homegenously aligned measurement cell having 15 μm thickness. Mechanism of molecular reorientation includes the absorbance effects of the energy of laser by doping dye and this reorientation causes the refractive index of the material to be changed. There are potential application possibilities of such molecular reorientation based effects in nonlinear optics such as real time holography whose basis is grating diffraction that is observed and investigated in the frame of fundamentals of molecule light interaction mechanisms. Experimental analyses allowed finding characteristic values of diffraction signals depending on physical parameters of set up for a dye doped liquid crystal system and this system provided a 20 % diffraction efficiency under the optimum circumstances
Time resolved X-ray micro-diffraction measurements of the dynamic local layer response to electric field in antiferroelectric liquid crystals

Energy Technology Data Exchange (ETDEWEB)

Takahashi, Yumiko; Iida, Atuso E-mail: atsuo.iida@kek.jp; Takanishi, Yoichi; Ogasawara, Toyokazu; Takezoe, Hideo

2001-07-21

The time-resolved synchrotron X-ray microbeam diffraction experiment has been carried out to reveal the local layer response to the electric field in the antiferroelectric liquid crystal. The X-ray microbeam of a few {mu}m spatial resolution was obtained with Kirkpatrick-Baez optics. The time-resolved small angle diffraction experiment was performed with a time resolution ranging from 10 {mu}s to a few ms. The reversible local layer change between the horizontal chevron and the quasi-bookshelf structure was confirmed by the triangular wave form. The transient layer response for the step form electric field was observed. The layer response closely related with an electric field induced antiferroelectric to ferroelectric phase transition.
Time resolved X-ray micro-diffraction measurements of the dynamic local layer response to electric field in antiferroelectric liquid crystals

International Nuclear Information System (INIS)

Takahashi, Yumiko; Iida, Atuso; Takanishi, Yoichi; Ogasawara, Toyokazu; Takezoe, Hideo

2001-01-01

The time-resolved synchrotron X-ray microbeam diffraction experiment has been carried out to reveal the local layer response to the electric field in the antiferroelectric liquid crystal. The X-ray microbeam of a few μm spatial resolution was obtained with Kirkpatrick-Baez optics. The time-resolved small angle diffraction experiment was performed with a time resolution ranging from 10 μs to a few ms. The reversible local layer change between the horizontal chevron and the quasi-bookshelf structure was confirmed by the triangular wave form. The transient layer response for the step form electric field was observed. The layer response closely related with an electric field induced antiferroelectric to ferroelectric phase transition
All-optical image processing with nonlinear liquid crystals

Science.gov (United States)

Hong, Kuan-Lun

Liquid crystals are fascinating materials because of several advantages such as large optical birefringence, dielectric anisotropic, and easily compatible to most kinds of materials. Compared to the electro-optical properties of liquid crystals widely applied in displays and switching application, transparency through most parts of wavelengths also makes liquid crystals a better candidate for all-optical processing. The fast response time of liquid crystals resulting from multiple nonlinear effects, such as thermal and density effect can even make real-time processing realized. In addition, blue phase liquid crystals with spontaneously self-assembled three dimensional cubic structures attracted academic attention. In my dissertation, I will divide the whole contents into six parts. In Chapter 1, a brief introduction of liquid crystals is presented, including the current progress and the classification of liquid crystals. Anisotropy and laser induced director axis reorientation is presented in Chapter 2. In Chapter 3, I will solve the electrostrictive coupled equation and analyze the laser induced thermal and density effect in both static and dynamic ways. Furthermore, a dynamic simulation of laser induced density fluctuation is proposed by applying finite element method. In Chapter 4, two image processing setups are presented. One is the intensity inversion experiment in which intensity dependent phase modulation is the mechanism. The other is the wavelength conversion experiment in which I can read the invisible image with a visible probe beam. Both experiments are accompanied with simulations to realize the matching between the theories and practical experiment results. In Chapter 5, optical properties of blue phase liquid crystals will be introduced and discussed. The results of grating diffractions and thermal refractive index gradient are presented in this chapter. In addition, fiber arrays imaging and switching with BPLCs will be included in this chapter
Nanoparticles in liquid crystals, and liquid crystals in nanoparticles

Science.gov (United States)

de Pablo, Juan

2015-03-01

Liquid crystals are remarkably sensitive to interfacial interactions. Small perturbations at a liquid crystal interface, for example, can be propagated over relatively long length scales, thereby providing the basis for a wide range of applications that rely on amplification of molecular events into macroscopic observables. Our recent research efforts have focused on the reverse phenomenon; that is, we have sought to manipulate the interfacial assembly of nanoparticles or the organization of surface active molecules by controlling the structure of a liquid crystal. This presentation will consist of a review of the basic principles that are responsible for liquid crystal-mediated interactions, followed by demonstrations of those principles in the context of two types of systems. In the first, a liquid crystal is used to direct the assembly of nanoparticles; through a combination of molecular and continuum models, it is found that minute changes in interfacial energy and particle size lead to liquid-crystal induced attractions that can span multiple orders of magnitude. Theoretical predictions are confirmed by experimental observations, which also suggest that LC-mediated assembly provides an effective means for fabrication of plasmonic devices. In the second type of system, the structure of a liquid crystal is controlled by confinement in submicron droplets. The morphology of the liquid crystal in a drop depends on a delicate balance between bulk and interfacial contributions to the free energy; that balance can be easily perturbed by adsorption of analytes or nanoparticles at the interface, thereby providing the basis for development of hierarchical assembly of responsive, anisotropic materials. Theoretical predictions also indicate that the three-dimensional order of a liquid crystal can be projected onto a two-dimensional interface, and give rise to novel nanostructures that are not found in simple isotropic fluids.
Steady distribution structure of point defects near crystal-melt interface under pulling stop of CZ Si crystal

Science.gov (United States)

Abe, T.; Takahashi, T.; Shirai, K.

2017-02-01

In order to reveal a steady distribution structure of point defects of no growing Si on the solid-liquid interface, the crystals were grown at a high pulling rate, which Vs becomes predominant, and the pulling was suddenly stopped. After restoring the variations of the crystal by the pulling-stop, the crystals were then left in prolonged contact with the melt. Finally, the crystals were detached and rapidly cooled to freeze point defects and then a distribution of the point defects of the as-grown crystals was observed. As a result, a dislocation loop (DL) region, which is formed by the aggregation of interstitials (Is), was formed over the solid-liquid interface and was surrounded with a Vs-and-Is-free recombination region (Rc-region), although the entire crystals had been Vs rich in the beginning. It was also revealed that the crystal on the solid-liquid interface after the prolonged contact with the melt can partially have a Rc-region to be directly in contact with the melt, unlike a defect distribution of a solid-liquid interface that has been growing. This experimental result contradicts a hypothesis of Voronkov's diffusion model, which always assumes the equilibrium concentrations of Vs and Is as the boundary condition for distribution of point defects on the growth interface. The results were disscussed from a qualitative point of view of temperature distribution and thermal stress by the pulling-stop.
Cyclic olefin homopolymer-based microfluidics for protein crystallization and in situ X-ray diffraction

International Nuclear Information System (INIS)

Emamzadah, Soheila; Petty, Tom J.; De Almeida, Victor; Nishimura, Taisuke; Joly, Jacques; Ferrer, Jean-Luc; Halazonetis, Thanos D.

2009-01-01

A cyclic olefin homopolymer-based microfluidics system has been established for protein crystallization and in situ X-ray diffraction. Microfluidics is a promising technology for the rapid identification of protein crystallization conditions. However, most of the existing systems utilize silicone elastomers as the chip material which, despite its many benefits, is highly permeable to water vapour. This limits the time available for protein crystallization to less than a week. Here, the use of a cyclic olefin homopolymer-based microfluidics system for protein crystallization and in situ X-ray diffraction is described. Liquid handling in this system is performed in 2 mm thin transparent cards which contain 500 chambers, each with a volume of 320 nl. Microbatch, vapour-diffusion and free-interface diffusion protocols for protein crystallization were implemented and crystals were obtained of a number of proteins, including chicken lysozyme, bovine trypsin, a human p53 protein containing both the DNA-binding and oligomerization domains bound to DNA and a functionally important domain of Arabidopsis Morpheus’ molecule 1 (MOM1). The latter two polypeptides have not been crystallized previously. For X-ray diffraction analysis, either the cards were opened to allow mounting of the crystals on loops or the crystals were exposed to X-rays in situ. For lysozyme, an entire X-ray diffraction data set at 1.5 Å resolution was collected without removing the crystal from the card. Thus, cyclic olefin homopolymer-based microfluidics systems have the potential to further automate protein crystallization and structural genomics efforts
Maximizing Macromolecule Crystal Size for Neutron Diffraction Experiments

Science.gov (United States)

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

2002-01-01

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

Science.gov (United States)

Zakri, Cécile; Blanc, Christophe; Grelet, Eric; Zamora-Ledezma, Camilo; Puech, Nicolas; Anglaret, Eric; Poulin, Philippe

2013-04-13

Liquid crystal ordering is an opportunity to develop novel materials and applications with spontaneously aligned nanotubes or graphene particles. Nevertheless, achieving high orientational order parameter and large monodomains remains a challenge. In addition, our restricted knowledge of the structure of the currently available materials is a limitation for fundamental studies and future applications. This paper presents recent methodologies that have been developed to achieve large monodomains of nematic liquid crystals. These allow quantification and increase of their order parameters. Nematic ordering provides an efficient way to prepare conductive films that exhibit anisotropic properties. In particular, it is shown how the electrical conductivity anisotropy increases with the order parameter of the nematic liquid crystal. The order parameter can be tuned by controlling the length and entanglement of the nanotubes. In the second part of the paper, recent results on graphene liquid crystals are reported. The possibility to obtain water-based liquid crystals stabilized by surfactant molecules is demonstrated. Structural and thermodynamic characterizations provide indirect but statistical information on the dimensions of the graphene flakes. From a general point of view, this work presents experimental approaches to optimize the use of nanocarbons as liquid crystals and provides new methodologies for the still challenging characterization of such materials.
muSR-Investigation of a Liquid Crystal Containing Iron Atoms

CERN Document Server

Mamedov, T N; Galyametdinov, Yu G; Gritsaj, K I; Herlach, D; Kormann, O; Major, J V; Rochev, V Ya; Stoikov, A V; Zimmermann, U

2000-01-01

The work is devoted to the investigation of properties of a liquid crystal whose molecule contains iron atom. The compounds of this type are of interest from the point of view of obtaining liquid crystals with magnetic properties. The temperature dependence of the polarization and relaxation rate of positive muon spin in the liquid crystal was measured in the temperature range 4-300 K. The results obtained do not contradict the suggestion that the iron ions from an antiferromagnetically-ordered structure in this liquid crystal at the temperatures below 80 K.

Soft Elasticity in Main Chain Liquid Crystal Elastomers

Directory of Open Access Journals (Sweden)

Anselm C. Griffin

2013-06-01

Full Text Available Main chain liquid crystal elastomers exhibit several interesting phenomena, such as three different regimes of elastic response, unconventional stress-strain relationship in one of these regimes, and the shape memory effect. Investigations are beginning to reveal relationships between their macroscopic behavior and the nature of domain structure, microscopic smectic phase structure, relaxation mechanism, and sample history. These aspects of liquid crystal elastomers are briefly reviewed followed by a summary of the results of recent elastic and high-resolution X-ray diffraction studies of the shape memory effect and the dynamics of the formation of the smectic-C chevron-like layer structure. A possible route to realizing auxetic effect at molecular level is also discussed.
Electric-field responsive contrast agent based on liquid crystals and magnetic nanoparticles

Science.gov (United States)

Mair, Lamar O.; Martinez-Miranda, Luz J.; Kurihara, Lynn K.; Nacev, Aleksandar; Hilaman, Ryan; Chowdhury, Sagar; Jafari, Sahar; Ijanaten, Said; da Silva, Claudian; Baker-McKee, James; Stepanov, Pavel Y.; Weinberg, Irving N.

2018-05-01

The properties of liquid crystal-magnetic nanoparticle composites have potential for sensing in the body. We study the response of a liquid crystal-magnetic nanoparticle (LC-MNP) composite to applied potentials of hundreds of volts per meter. Measuring samples using X-ray diffraction (XRD) and imaging composites using magnetic resonance imaging (MRI), we demonstrate that electric potentials applied across centimeter scale LC-MNP composite samples can be detected using XRD and MRI techniques.
New scintillating media based on liquid crystals for particle detectors

International Nuclear Information System (INIS)

Barnik, M.I.; Yudin, S.G.; Vasil'chenko, V.G.; Golovkin, S.V.; Medvedkov, A.M.; Solovjev, A.S.

2000-01-01

The study results of optical, photoluminiscent and scintillation properties of a liquid crystal 4-pentyl-4'-cyanobiphenyl are presented. The scintillation light output of this liquid crystal is about 35% of crystal anthracene, its main decay time constants are 4 and 14 ns, and the maximum of light emission spectrum is about 400 nm. The light output of a dissolution of green emitting light scintillation dopant R6 in the liquid crystal is about 120% of crystal anthracene. The light output of the frozen dissolution measured at -112 deg. C is about 2.5 times higher as observed at +20 deg. C. In the uniaxially oriented liquid crystal, the predominant intensity direction of emitted light is pointed perpendicular to the liquid crystal director and an appreciable part of the emitted light is elliptically polarized. The possibility to use scintillation properties of liquid crystals is considered both for the improvement of existing particle detector characteristics and for the creation of new gated particle detectors
New scintillating media based on liquid crystals for particle detectors

CERN Document Server

Barnik, M I; Vasilchenko, V G; Golovkin, S V; Medvedkov, A M; Soloviev, A S

2000-01-01

The study results of optical, photoluminiscent and scintillation properties of a liquid crystal 4-pentyl-4'-cyanobiphenyl are presented. The scintillation light output of this liquid crystal is about 35% of crystal anthracene, its main decay time constants are 4 and 14 ns, and the maximum of light emission spectrum is about 400 nm. The light output of a dissolution of green emitting light scintillation dopant R6 in the liquid crystal is about 120% of crystal anthracene. The light output of the frozen dissolution measured at -112 deg. C is about 2.5 times higher as observed at +20 deg. C. In the uniaxially oriented liquid crystal, the predominant intensity direction of emitted light is pointed perpendicular to the liquid crystal director and an appreciable part of the emitted light is elliptically polarized. The possibility to use scintillation properties of liquid crystals is considered both for the improvement of existing particle detector characteristics and for the creation of new gated particle detectors.
Diffraction. Powder, amorphous, liquid

International Nuclear Information System (INIS)

Sosnowska, I.M.

1999-01-01

Neutron powder diffraction is a unique tool to observe all possible diffraction effects appearing in crystal. High-resolution neutron diffractometers have to be used in this study. Analysis of the magnetic structure of polycrystalline materials requires the use of high-resolution neutron diffraction in the range of large interplanar distances. As distinguished from the double axis diffractometers (DAS), which show high resolution only at small interplanar distances, TOF (time-of-flight) diffractometry offers the best resolution at large interplanar distances. (K.A.)
Microwave modulation characteristics of twisted liquid crystals with chiral dopant

Directory of Open Access Journals (Sweden)

Rui Yuan

2017-01-01

Full Text Available Adding a chiral dopant in twisted nematic (TN liquid crystal cell can stabilize the orientation of liquid crystal molecules, particularly in high TN (HTN or super TN (STN liquid crystal cells. The difference in pitches in liquid crystal is induced by the chiral dopant, and these different pitches affect the orientation of liquid crystal director under an external applied voltage and influence the characteristics of microwave modulation. To illustrate this point, the microwave phase shift per unit length (MPSL versus voltage is calculated on the basis of the elastic theory of liquid crystal and the finite-difference iterative method. Enhancing the pitch induced by the chiral dopant in liquid crystal increases the MPSLs, but the stability of the twisted structures is decreased. Thus, appropriate pitches of 100d, 4d, and 2d can be applied in TN, HTN, and STN cells with cell gap d to enhance the characteristics of microwave modulation and stabilize the structures in twisted cell. This method can improve the characteristics of liquid crystal microwave modulators such that the operating voltage and the size of such phase shifters can be decreased.
Femtosecond X-ray diffraction from two-dimensional protein crystals

Directory of Open Access Journals (Sweden)

Matthias Frank

2014-03-01

Full Text Available X-ray diffraction patterns from two-dimensional (2-D protein crystals obtained using femtosecond X-ray pulses from an X-ray free-electron laser (XFEL are presented. To date, it has not been possible to acquire transmission X-ray diffraction patterns from individual 2-D protein crystals due to radiation damage. However, the intense and ultrafast pulses generated by an XFEL permit a new method of collecting diffraction data before the sample is destroyed. Utilizing a diffract-before-destroy approach at the Linac Coherent Light Source, Bragg diffraction was acquired to better than 8.5 Å resolution for two different 2-D protein crystal samples each less than 10 nm thick and maintained at room temperature. These proof-of-principle results show promise for structural analysis of both soluble and membrane proteins arranged as 2-D crystals without requiring cryogenic conditions or the formation of three-dimensional crystals.
Angular selectivity asymmetry of holograms recorded in near infrared sensitive liquid crystal photopolymerizable materials

Science.gov (United States)

Harbour, Steven; Galstian, Tigran; Akopyan, Rafik; Galstyan, Artur

2004-08-01

We have experimentally observed and theoretically explained the angular selectivity asymmetry in polymer dispersed liquid crystal holograms. Experiments are conducted in compounds with near infrared sensitivity. The coupled-wave theory is used to describe the diffraction properties of obtained anisotropic holographic gratings. Furthermore, the comparison of theory and experiments provides information about the optical axis direction that is defined by the average molecular orientation of the liquid crystal in the polymer matrix.
Influence of the crystal-surface unevenness on the angular spread of an x-ray diffracted beam

International Nuclear Information System (INIS)

Hrda, JaromIra; Potlovskiy, Kirill; Hrdy, JaromIr; Slechtova, Venceslava

2005-01-01

One of the factors influencing the focus size in diffractive-refractive optics is the quality of diffracting surface. If the surface is uneven, as it is when the silicon crystal surface is only etched, then the diffraction at each point of the surface is a combination of an asymmetric and inclined diffraction (general asymmetric diffraction). This somewhat deviates and spreads the diffracted beam. The integration over the surface hit by an incident beam gives the angular spread of the diffracted beam. It is shown theoretically that in some cases (highly asymmetric, highly inclined cut) the etched surface may create the spread of the diffracted beam such that it causes a significant broadening of the focus. In this case a mechanical-chemical polishing is necessary. This has been verified by us earlier in a preliminary experiment with synchrotron radiation. In this work the new experiment with the same crystals is performed using double crystal (+, -) arrangement and a laboratory x-ray source (CuKα radiation). We compared two samples; one of them is mechanically-chemically (MC) polished and thus the diffracting surface is almost perfect; the other is only etched. This experiment allows a better comparison of the result with the theory. The difference between the measured rocking curve widths for the etched and MC polished crystals (10'') roughly agrees with theory (7''), which supports the correctness of the theoretical approach
Metric approach for sound propagation in nematic liquid crystals

Science.gov (United States)

Pereira, E.; Fumeron, S.; Moraes, F.

2013-02-01

In the eikonal approach, we describe sound propagation near topological defects of nematic liquid crystals as geodesics of a non-Euclidian manifold endowed with an effective metric tensor. The relation between the acoustics of the medium and this geometrical description is given by Fermat's principle. We calculate the ray trajectories and propose a diffraction experiment to retrieve information about the elastic constants.
Diffraction. Single crystal, magnetic

International Nuclear Information System (INIS)

Heger, G.

1999-01-01

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.)
HOLOGRAPHIC GRATING RECORDING IN “LYOTROPIC LIQUID CRYSTAL – VIOLOGEN” SYSTEM

Directory of Open Access Journals (Sweden)

Hanna Bordyuh

2013-12-01

Full Text Available This work presents the results of nonlinear optical experiment run on the samples of lyotropic liquid crystal (LLC with viologen admixtures. During the experiment we obtained dynamic grating recording on bilayered LLC-viologen samples and determined main characteristics of recoded gratings. It was found out that the recording takes place in a thin near-cathode coloured viologen layer. The analysis of kinetics of thermal gratings erasing showed that contribution of a thermal nonlinearity into general diffraction efficiency is negligible small. The last fact is connected with a separation of LLC-viologen samples under the action of an electric field and heat sink into the liquid crystal layer
Laser diffraction analysis of colloidal crystals

Energy Technology Data Exchange (ETDEWEB)

Sogami, Ikuo S.; Shinohara, Tadatomi; Yoshiyama, Tsuyoshi [Kyoto Sangyo Univ., Department of Physics, Kyoto (Japan)

2001-10-01

Laser diffraction analysis is made on crystallization in salt-free aqueous suspensions of highly-charged colloidal particles for semi-dilute specimens of concentration 0.1-10.0 vol%. Kossel diffraction patterns which represent faithfully accurate information on lattice symmetries in the suspensions enable us to investigate the time evolution of colloidal crystals. The results show that the crystallization proceeds by way of the following intermediate phase transitions: two-dimensional hcp structure {yields} random layer structure {yields} layer structure with one sliding degree of freedom {yields} stacking disorder structure {yields} stacking structure with multivariant periodicity {yields} fcc twin structure with twin plane (111) {yields} normal fcc structure {yields} bcc twin structure with twin plane (11-bar2) or (1-bar12) {yields} normal bcc structure. For concentrated suspensions (>2 vol %), the phase transition ceases to proceed at the normal fcc structure. (author)
Laser diffraction analysis of colloidal crystals

International Nuclear Information System (INIS)

Sogami, Ikuo S.; Shinohara, Tadatomi; Yoshiyama, Tsuyoshi

2001-01-01

Laser diffraction analysis is made on crystallization in salt-free aqueous suspensions of highly-charged colloidal particles for semi-dilute specimens of concentration 0.1-10.0 vol%. Kossel diffraction patterns which represent faithfully accurate information on lattice symmetries in the suspensions enable us to investigate the time evolution of colloidal crystals. The results show that the crystallization proceeds by way of the following intermediate phase transitions: two-dimensional hcp structure → random layer structure → layer structure with one sliding degree of freedom → stacking disorder structure → stacking structure with multivariant periodicity → fcc twin structure with twin plane (111) → normal fcc structure → bcc twin structure with twin plane (11-bar2) or (1-bar12) → normal bcc structure. For concentrated suspensions (>2 vol %), the phase transition ceases to proceed at the normal fcc structure. (author)
Liquid Crystal Colloids

Science.gov (United States)

Smalyukh, Ivan I.

2018-03-01

Colloids are abundant in nature, science, and technology, with examples ranging from milk to quantum dots and the colloidal atom paradigm. Similarly, liquid crystal ordering is important in contexts ranging from biological membranes to laboratory models of cosmic strings and liquid crystal displays in consumer devices. Some of the most exciting recent developments in both of these soft matter fields emerge at their interface, in the fast-growing research arena of liquid crystal colloids. Mesoscale self-assembly in such systems may lead to artificial materials and to structures with emergent physical behavior arising from patterning of molecular order and nano- or microparticles into precisely controlled configurations. Liquid crystal colloids show exceptional promise for new discovery that may impinge on composite material fabrication, low-dimensional topology, photonics, and so on. Starting from physical underpinnings, I review the state of the art in this fast-growing field, with a focus on its scientific and technological potential.
Diffraction and single-crystal elastic constants of Inconel 625 at room and elevated temperatures determined by neutron diffraction

International Nuclear Information System (INIS)

Wang, Zhuqing; Stoica, Alexandru D.; Ma, Dong; Beese, Allison M.

2016-01-01

In this work, diffraction and single-crystal elastic constants of Inconel 625 have been determined by means of in situ loading at room and elevated temperatures using time-of-flight neutron diffraction. Theoretical models proposed by Voigt, Reuss, and Kroner were used to determine single-crystal elastic constants from measured diffraction elastic constants, with the Kroner model having the best ability to capture experimental data. The magnitude of single-crystal elastic moduli, computed from single-crystal elastic constants, decreases and the single crystal anisotropy increases as temperature increases, indicating the importance of texture in affecting macroscopic stress at elevated temperatures. The experimental data reported here are of great importance in understanding additive manufacturing of metallic components as: diffraction elastic constants are required for computing residual stresses from residual lattice strains measured using neutron diffraction, which can be used to validate thermomechanical models of additive manufacturing, while single-crystal elastic constants can be used in crystal plasticity modeling, for example, to understand mechanical deformation behavior of additively manufactured components.
Diffraction and single-crystal elastic constants of Inconel 625 at room and elevated temperatures determined by neutron diffraction

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhuqing [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Stoica, Alexandru D. [Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Ma, Dong, E-mail: dongma@ornl.gov [Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Beese, Allison M., E-mail: amb961@psu.edu [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States)

2016-09-30

In this work, diffraction and single-crystal elastic constants of Inconel 625 have been determined by means of in situ loading at room and elevated temperatures using time-of-flight neutron diffraction. Theoretical models proposed by Voigt, Reuss, and Kroner were used to determine single-crystal elastic constants from measured diffraction elastic constants, with the Kroner model having the best ability to capture experimental data. The magnitude of single-crystal elastic moduli, computed from single-crystal elastic constants, decreases and the single crystal anisotropy increases as temperature increases, indicating the importance of texture in affecting macroscopic stress at elevated temperatures. The experimental data reported here are of great importance in understanding additive manufacturing of metallic components as: diffraction elastic constants are required for computing residual stresses from residual lattice strains measured using neutron diffraction, which can be used to validate thermomechanical models of additive manufacturing, while single-crystal elastic constants can be used in crystal plasticity modeling, for example, to understand mechanical deformation behavior of additively manufactured components.
Symmetry, stability, and diffraction properties of icosahedral crystals

International Nuclear Information System (INIS)

Bak, P.

1985-01-01

In a remarkable experiment on an Mn-Al alloy, Shechtman et al. observed a diffraction spectrum with icosahedral symmetry. This is inconsistent with discrete translational invariance since the symmetry includes a five-fold axis. In this paper, it is shown that the crystallography and diffraction pattern can be described by a six-dimensional space group. The crystal structure in 3d is obtained as a cut along a 3d hyperplane in a regular 6d crystal. Displacements of the 6d crystal along 6 orthogonal directions define 6 continuous symmetries for the icosahedral crystal, three of which are phase symmetries describing internal rearrangements of the atoms
Dynamical neutron diffraction by curved crystals in the Laue geometry

International Nuclear Information System (INIS)

Albertini, G.; Melone, S.; Lagomarsino, S.; Mazkedian, S.; Puliti, P.; Rustichelli, F.

1977-01-01

The Taupin dynamical theory of X-ray diffraction by deformed crystals which was previously extended to the neutron diffraction by curved crystals in the Bragg geometry, is applied to calculate neutron diffraction patterns in the Laue geometry. The theoretical results are compared with experimental data on curved silicon crystals. The agreement is quite satisfactory. In the second part a simple model recently presented to describe neutron diffraction properties in the Bragg case is extended to the Laue case. The predictions of such a model are in satisfactory agreement with the rigorous theory and the experimental results. (author)
Improving the diffraction of apoA-IV crystals through extreme dehydration

International Nuclear Information System (INIS)

Deng, Xiaodi; Davidson, W. Sean; Thompson, Thomas B.

2011-01-01

Apolipoprotein A-IV crystals consisted of a long unit-cell edge (540 Å) with a high mosaic spread, making them intractable for X-ray diffraction analysis. Extreme dehydration in 60% PEG 3350 was utilized as a post-crystallization treatment as well a screening method to significantly sharpen the mosaic spread and increase the overall resolution of diffraction. Apolipoproteins are the protein component of high-density lipoproteins (HDL), which are necessary for mobilizing lipid-like molecules throughout the body. Apolipoproteins undergo self-association, especially at higher concentrations, making them difficult to crystallize. Here, the crystallization and diffraction of the core fragment of apolipoprotein A-IV (apoA-IV), consisting of residues 64–335, is presented. ApoA-IV 64–335 crystallized readily in a variety of hexagonal (P6) morphologies with similar unit-cell parameters, all containing a long axis of nearly 550 Å in length. Preliminary diffraction experiments with the different crystal morphologies all resulted in limited streaky diffraction to 3.5 Å resolution. Crystal dehydration was applied to the different morphologies with variable success and was also used as a quality indicator of crystal-growth conditions. The results show that the morphologies that withstood the most extreme dehydration conditions showed the greatest improvement in diffraction. One morphology in particular was able to withstand dehydration in 60% PEG 3350 for over 12 h, which resulted in well defined intensities to 2.7 Å resolution. These results suggest that the approach of integrating dehydration with variation in crystal-growth conditions might be a general technique to optimize diffraction

Analysis of the unmodulated diffraction beam of the phase-only liquid crystal spatial light modulator and a method for reducing its influence

International Nuclear Information System (INIS)

Qi, Yue; Li, Dayu; Hu, Lifa; Xuan, Li; Xia, Mingliang

2012-01-01

As a wavefront corrector, the phase-only liquid crystal spatial light modulator has been widely using in adaptive optics systems. However, the unmodulated diffracted beam of the modulator will affect the light spot centroid detection accuracy of a Shack–Hartmann wavefront sensor and decrease the image quality after correction. In this paper, we have diminished the effect by introducing a modified weight algorithm in our closed-loop adaptive optics system. The Strehl ratio of the image is higher than 0.8 after correction, even when the wavefront aberration is larger than 3 μm. The correction precision and image quality are both improved significantly. (paper)
Physical Properties of Liquid Crystals

CERN Document Server

Gray, George W; Spiess, Hans W

1999-01-01

This handbook is a unique compendium of knowledge on all aspects of the physics of liquid crystals. In over 500 pages it provides detailed information on the physical properties of liquid crystals as well as the recent theories and results on phase transitions, defects and textures of different types of liquid crystals. An in-depth understanding of the physical fundamentals is a prerequisite for everyone working in the field of liquid crystal research. With this book the experts as well as graduate students entering the field get all the information they need.
The sweet world of liquid crystals : The synthesis of non-amphiphilic carbohydrate-derived liquid crystals

NARCIS (Netherlands)

Smits, E

1998-01-01

The research in carbohydrate-derived liquid crystals was initiated by a review article by Jeffrey in 1986. This is rather late if one considers that the research on liquid crystals underwent a revival already in the 1960s after the discovery of the liquid crystal display (LCD). Carbohydrates were
Pressure sensor using liquid crystals

Science.gov (United States)

Parmar, Devendra S. (Inventor); Holmes, Harlan K. (Inventor)

1994-01-01

A pressure sensor includes a liquid crystal positioned between transparent, electrically conductive films (18 and 20), that are biased by a voltage (V) which induces an electric field (E) that causes the liquid crystal to assume a first state of orientation. Application of pressure (P) to a flexible, transparent film (24) causes the conductive film (20) to move closer to or farther from the conductive film (18), thereby causing a change in the electric field (E'(P)) which causes the liquid crystal to assume a second state of orientation. Polarized light (P.sub.1) is directed into the liquid crystal and transmitted or reflected to an analyzer (A or 30). Changes in the state of orientation of the liquid crystal induced by applied pressure (P) result in a different light intensity being detected at the analyzer (A or 30) as a function of the applied pressure (P). In particular embodiments, the liquid crystal is present as droplets (10) in a polymer matrix (12) or in cells (14) in a polymeric or dielectric grid (16) material in the form of a layer (13) between the electrically conductive films (18 and 20). The liquid crystal fills the open wells in the polymer matrix (12) or grid (16) only partially.
NMR studies of liquid crystals and molecules dissolved in liquid crystal solvents

Energy Technology Data Exchange (ETDEWEB)

Drobny, Gary Peter [Univ. of California, Berkeley, CA (United States)

1982-11-01

zero at the smectic A - smectic C transition and reaching a maximum at 9° at the smectic C - smectic B_A transition. This finding contradicts the results of X-ray diffraction studies which indicate that the tilt angle is 18° and temperature independent. The smectic B_A - smectic B_C phase transition is observed for the first time, and is found to be first order, a result that contradicts the prediction of a mean theory by McMillian. Chapter 3 is a multiple quantum nmr study of n-hexane oriented in a nematic liquid crystal solvent. The basic three pulse multiple quantum experiment is discussed which enables the observation of transitions for which |Δm|>1, and then the technique of the separation of multiple quantum orders by phase incrementation in the multiple quantum evolution period is reviewed (TPPI). An explicit example of multiple quantum nmr is given by the calculation of the multiple quantum spectrum of an oriented methyl group.
Variable-metric diffraction crystals for x-ray optics

International Nuclear Information System (INIS)

Smither, R.K.; Fernandez, P.B.

1992-01-01

A variable-metric (VM) crystal is one in which the spacing between the crystalline planes changes with position in the crystal. This variation can be either parallel to the crystalline planes or perpendicular to the crystalline planes of interest and can be produced by either introducing a thermal gradient in the crystal or by growing a crystal made of two or more elements and changing the relative percentages of the two elements as the crystal is grown. A series of experiments were performed in the laboratory to demonstrate the principle of the variable-metric crystal and its potential use in synchrotron beam lines. One of the most useful applications of the VM crystal is to increase the number of photons per unit bandwidth in a diffracted beam without losing any of the overall intensity. In a normal synchrotron beam line that uses a two-crystal monochromator, the bandwidth of the diffracted photon beam is determined by the vertical opening angle of the beam which is typically 0.10--0.30 mrad or 20--60 arcsec. When the VM crystal approach is applied, the bandwidth of the beam can be made as narrow as the rocking curve of the diffracting crystal, which is typically 0.005--0.050 mrad or 1--10 arcsec. Thus a very large increase of photons per unit bandwidth (or per unit energy) can be achieved through the use of VM crystals. When the VM principle is used with bent crystals, new kinds of x-ray optical elements can be generated that can focus and defocus x-ray beams much like simple lenses where the focal length of the lens can be changed to match its application. Thus both large magnifications and large demagnifications can be achieved as well as parallel beams with narrow bandwidths
A finite element beam propagation method for simulation of liquid crystal devices.

Science.gov (United States)

Vanbrabant, Pieter J M; Beeckman, Jeroen; Neyts, Kristiaan; James, Richard; Fernandez, F Anibal

2009-06-22

An efficient full-vectorial finite element beam propagation method is presented that uses higher order vector elements to calculate the wide angle propagation of an optical field through inhomogeneous, anisotropic optical materials such as liquid crystals. The full dielectric permittivity tensor is considered in solving Maxwell's equations. The wide applicability of the method is illustrated with different examples: the propagation of a laser beam in a uniaxial medium, the tunability of a directional coupler based on liquid crystals and the near-field diffraction of a plane wave in a structure containing micrometer scale variations in the transverse refractive index, similar to the pixels of a spatial light modulator.
Modeling liquid crystal polymeric devices

Science.gov (United States)

Gimenez Pinto, Vianney Karina

The main focus of this work is the theoretical and numerical study of materials that combine liquid crystal and polymer. Liquid crystal elastomers are polymeric materials that exhibit both the ordered properties of the liquid crystals and the elastic properties of rubbers. Changing the order of the liquid crystal molecules within the polymer network can induce shape change. These materials are very valuable for applications such as actuators, sensors, artificial muscles, haptic displays, etc. In this work we apply finite element elastodynamics simulations to study the temperature induced shape deformation in nematic elastomers with complex director microstructure. In another topic, we propose a novel numerical method to model the director dynamics and microstructural evolution of three dimensional nematic and cholesteric liquid crystals. Numerical studies presented in this work are in agreement with experimental observations and provide insight into the design of application devices.
Liquid Crystals in Decorative and Visual Arts

Science.gov (United States)

Makow, David

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

International Nuclear Information System (INIS)

Morisaki, T.; Ono, H.

2005-01-01

A laser-induced liquid-crystal lens is formed by large optical non-linearity and anisotropic complex refractive indices in guest-host liquid crystals. We obtained light wave propagation characteristics of the laser-induced LC lens. Three analytical methods were used to obtain light wave propagation characteristics. Analysis by 3-dimensional heat conduction was applied to determine the refractive index in the liquid-crystal layer. Another method used was to determine light wave propagation characteristics in the laser-induced lens by means of the finite-difference tune domain (FDTD) method and diffraction theory. In this study, we draw a parallel between the experimental results and FDTD. Copyright (2003) AD-TECH - International Foundation for the Advancement of Technology Ltd
Wetting of cholesteric liquid crystals.

Science.gov (United States)

Silvestre, Nuno M; Figueirinhas Pereira, Maria Carolina; Bernardino, Nelson R; Telo da Gama, Margarida M

2016-02-01

We investigate theoretically the wetting properties of cholesteric liquid crystals at a planar substrate. If the properties of substrate and of the interface are such that the cholesteric layers are not distorted, the wetting properties are similar to those of a nematic liquid crystal. If, on the other hand, the anchoring conditions force the distortion of the liquid crystal layers the wetting properties are altered, the free cholesteric-isotropic interface is non-planar and there is a layer of topological defects close to the substrate. These deformations can either promote or hinder the wetting of the substrate by a cholesteric, depending on the properties of the cholesteric liquid crystal.
The bent crystal diffraction spectrometer at the BR2 reactor in Mol

Science.gov (United States)

Kaerts, E.; Jacobs, L.; Vandenput, G.; Van Assche, P. H. M.

1988-05-01

The DuMond-type bent crystal diffraction spectrometer installed at the BR2 reactor in Mol is presented. The spectrometer is mainly designed to study nuclear γ-transitions following thermal neutron capture. It covers the energy interval 25 ≦ Eγ ≦ 1500 keV. Instead of the traditionally used quartz crystals, a highly perfect silicium crystal is chosen as analysing crystal. Diffraction occurs from the (220) plane. The "quasi-mosaic" width, introduced by bending the crystal, is as small as 0.2″. The integrated reflecting power R of the bent crystal stays constant up to 1.5 MeV in first, 680 keV in second and 300 keV in third diffraction order. For higher photon energies, only an E-1 energy dependence is observed in second and third diffraction order. Consequently, besides improving the energy resolution, the use of these silicium crystals substantially increases the spectrometer efficiency and extends the high energy limit of bent crystal diffraction spectrometers. The diffraction angles are measured with a symmetrical interferometer system which covers an angular range of -6° to +6° with a precision of about 0.01″. Minimum diffraction line widths of 0.9″ have been measured, corresponding to an energy resolution ΔE = 1.35 × 10 -6E2n-1 keV -1. The dominant contribution to the observed line widths arises from the finite extent of the source.
Feasibility of one-shot-per-crystal structure determination using Laue diffraction

Energy Technology Data Exchange (ETDEWEB)

Cornaby, Sterling [School of Applied and Engineering Physics, Cornell University, Ithaca, New York (United States); CHESS (Cornell High Energy Synchrotron Source), Cornell University, Ithaca, New York (United States); Szebenyi, Doletha M. E. [MacCHESS (Macromolecular Diffraction Facilities at CHESS), Cornell University, Ithaca, New York (United States); Smilgies, Detlef-M. [CHESS (Cornell High Energy Synchrotron Source), Cornell University, Ithaca, New York (United States); Schuller, David J.; Gillilan, Richard; Hao, Quan [MacCHESS (Macromolecular Diffraction Facilities at CHESS), Cornell University, Ithaca, New York (United States); Bilderback, Donald H., E-mail: dhb2@cornell.edu [School of Applied and Engineering Physics, Cornell University, Ithaca, New York (United States); CHESS (Cornell High Energy Synchrotron Source), Cornell University, Ithaca, New York (United States)

2010-01-01

Structure determination was successfully carried out using single Laue exposures from a group of lysozyme crystals. The Laue method may be a viable option for collection of one-shot-per-crystal data from microcrystals. Crystal size is an important factor in determining the number of diffraction patterns which may be obtained from a protein crystal before severe radiation damage sets in. As crystal dimensions decrease this number is reduced, eventually falling to one, at which point a complete data set must be assembled using data from multiple crystals. When only a single exposure is to be collected from each crystal, the polychromatic Laue technique may be preferable to monochromatic methods owing to its simultaneous recording of a large number of fully recorded reflections per image. To assess the feasibility of solving structures using single Laue images from multiple crystals, data were collected using a ‘pink’ beam at the CHESS D1 station from groups of lysozyme crystals with dimensions of the order of 20–30 µm mounted on MicroMesh grids. Single-shot Laue data were used for structure determination by molecular replacement and correct solutions were obtained even when as few as five crystals were used.
Feasibility of one-shot-per-crystal structure determination using Laue diffraction

International Nuclear Information System (INIS)

Cornaby, Sterling; Szebenyi, Doletha M. E.; Smilgies, Detlef-M.; Schuller, David J.; Gillilan, Richard; Hao, Quan; Bilderback, Donald H.

2010-01-01

Structure determination was successfully carried out using single Laue exposures from a group of lysozyme crystals. The Laue method may be a viable option for collection of one-shot-per-crystal data from microcrystals. Crystal size is an important factor in determining the number of diffraction patterns which may be obtained from a protein crystal before severe radiation damage sets in. As crystal dimensions decrease this number is reduced, eventually falling to one, at which point a complete data set must be assembled using data from multiple crystals. When only a single exposure is to be collected from each crystal, the polychromatic Laue technique may be preferable to monochromatic methods owing to its simultaneous recording of a large number of fully recorded reflections per image. To assess the feasibility of solving structures using single Laue images from multiple crystals, data were collected using a ‘pink’ beam at the CHESS D1 station from groups of lysozyme crystals with dimensions of the order of 20–30 µm mounted on MicroMesh grids. Single-shot Laue data were used for structure determination by molecular replacement and correct solutions were obtained even when as few as five crystals were used
Crystal diffraction lens telescope for focusing nuclear gamma rays

International Nuclear Information System (INIS)

Smither, R.K.; Fernandez, P.B.; Graber, T.; Faiz, M.

1996-08-01

A crystal diffraction lens was constructed at Argonne National Laboratory for use as a telescope to focus nuclear gamma rays. It consisted of 600 single crystals of germanium arranged in 8 concentric rings. The mounted angle of each crystal was adjusted to intercept and diffract the incoming gamma rays with an accuracy of a few arc sec. The performance of the lens was tested in two ways. In one case, the gamma rays were focused on a single medium size germanium detector. In the second case, the gamma rays were focused on the central germanium detector of a 3 x 3 matrix of small germanium detectors. The efficiency, image concentration and image quality, and shape were measured. The tests performed with the 3 x 3 matrix detector system were particularly interesting. The wanted radiation was concentrated in the central detector. The 8 other detectors were used to detect the Compton scattered radiation, and their energy was summed with coincident events in the central detector. This resulted in a detector with the efficiency of a large detector (all 9 elements) and the background of a small detector (only the central element). The use of the 3 x 3 detector matrix makes it possible to tell if the source is off axis and, if so, to tell in which direction. The crystal lens acts very much like a simple convex lens for visible light. Thus if the source is off to the left then the image will focus off to the right illuminating the detector on the right side: telling one in which direction to point the telescope. Possible applications of this type of crystal lens to balloon and satellite experiments will be discussed
Anisotropic Light Diffraction by Ultrasound in Crystals with Strong Acoustic Anisotropy

Science.gov (United States)

Voloshin, Andrey S.; Balakshy, Vladimir I.

In modern acousto-optics, crystalline materials are used predominantly for manufacturing acousto-optic instruments. Among these materials, such crystals as paratellurite, tellurium, calomel, TAS and some others occupy a prominent place, which are distinguished by exceptionally large anisotropy of acoustic properties. In this work, the influence of acoustic beam energy walk-off on characteristics of Bragg diffraction of light is studied by the example of tellurium crystal. It is shown that the walk-off can substantially change angular and frequency ranges, resulting in their narrowing or broadening subject to position of the operating point in the Bragg angle frequency characteristic. Coefficients of broadening are introduced for characterization of this effect.
Structure analysis of liquids and disordered materials using pulsed neutron diffraction and total scattering

International Nuclear Information System (INIS)

Suzuya, Kentaro

2011-01-01

Neutron diffraction·total scattering at pulsed neutron source is a powerful method to analyze the complex structure of disordered materials: liquids, glasses, amorphous materials and disordered crystals. The basic idea of the structure of disordered materials, the fundamental diffraction theory for disordered materials, and structure analysis of disordered materials using pulsed neutron diffraction·total scattering technique (TOF method) are described in detail. In addition, the precise information of the world highest class J-PARC MLF spallation neutron source and typical J-PARC neutron total scattering instrument NOVA are also given. Recent structural modelling methods of disordered materials such like reverse Monte Carlo (RMC) simulation method is briefly described using an example of the analysis of a typical disordered material silica glass. (author)
A quartz crystal microbalance dew point sensor without frequency measurement

Science.gov (United States)

Wang, Guohua; Zhang, Weishuo; Wang, Shuo; Sun, Jinglin

2014-11-01

This work deals with the design of a dew point sensor based on Quartz Crystal Microbalance (QCM) without measuring the frequency. This idea is inspired by the fact that the Colpitts oscillation circuit will stop oscillating when the QCM works in the liquid media. The quartz crystal and the electrode are designed through the finite element simulation and the stop oscillating experiment is conducted to verify the sensibility. Moreover, the measurement result is calibrated to approach the true value. At last a series of dew points at the same temperature is measured with the designed sensor. Results show that the designed dew point sensor is able to detect the dew point with the proper accuracy.
Crystallization and preliminary X-ray diffraction analysis of West Nile virus

International Nuclear Information System (INIS)

Kaufmann, Bärbel; Plevka, Pavel; Kuhn, Richard J.; Rossmann, Michael G.

2010-01-01

Crystals of infectious West Nile virus were obtained and diffracted at best to about 25 Å resolution. Preliminary analysis of the diffraction pattern suggested tight hexagonal packing of the intact virus. West Nile virus, a human pathogen, is closely related to other medically important flaviviruses of global impact such as dengue virus. The infectious virus was purified from cell culture using polyethylene glycol (PEG) precipitation and density-gradient centrifugation. Thin amorphously shaped crystals of the lipid-enveloped virus were grown in quartz capillaries equilibrated by vapor diffusion. Crystal diffraction extended at best to a resolution of about 25 Å using synchrotron radiation. A preliminary analysis of the diffraction images indicated that the crystals had unit-cell parameters a ≃ b ≃ 480 Å, γ = 120°, suggesting a tight hexagonal packing of one virus particle per unit cell
Moessbauer diffraction study of the Neel phase transition in Fe3BO6 crystal

International Nuclear Information System (INIS)

Kovalenko, P.P.; Labushkin, V.G.; Sarkisov, Eh.R.; Tolpekin, I.G.

1987-01-01

Phase transitions in a 57 Fe 3 BO 6 monocrystal in the vicinity of the Neel point, T N =507.5 K were investigated by means of the Moessbauergraphy. For the first time the relaxation type of Moessbauer spectra was observed near the phase transition point. First in the Moessbauer diffraction spectrum of the crystal the simultaneous presence of a component resulted from magnetic ordering and a paramagnetic component was observed

Single-Crystal Diffraction from Two-Dimensional Block Copolymer Arrays

International Nuclear Information System (INIS)

Stein, G. E.; Kramer, E. J.; Li, X.; Wang, J.

2007-01-01

The structure of oriented 2D block copolymer single crystals is characterized by grazing-incidence small-angle x-ray diffraction, demonstrating long-range sixfold orientational order. From line shape analysis of the higher-order Bragg diffraction peaks, we determine that translational order decays algebraically with a decay exponent η=0.2, consistent with the Kosterlitz-Thouless-Halperin-Nelson-Young theory for a 2D crystal with a shear modulus μ=2x10 -4 N/m
Integrated intensities and flipping ratios in neutron diffraction by perfect magnetic crystals

International Nuclear Information System (INIS)

Guigay, J.P.; Schlenker, M.

1979-01-01

A theoretical study of neutron diffraction by perfect magnetic crystals is presented which shows that when the magnetization is perpendicular to the diffraction vector (β- π/2), the dispersion surface is made up of two hyperbolic surfaces corresponding to simple polarization states and the results of the two-beam dynamical theory for non-magnetic crystals can be directly applied. The asymptotic properties of the dispersion surface are of the dispersion surface are also discussed in the more general case (β is not equal to π/2) and an analytical treatment of the kinematical limit is presented. Integrated intensities and flipping ratios outside this limit can only be calculated numerically. It is shown that the wave fields defined by the different points of the dispersion surface are polarized in the (g, B 0 ) plane; this is a generalization of the fact that they are (+-) states with respect to B 0 in the simple case (β=π/2). (UK)
The study of the elasticity of spider dragline silk with liquid crystal model

International Nuclear Information System (INIS)

Cui Linying; Liu Fei; Ouyang Zhongcan

2009-01-01

Spider dragline silk is an optimal biomaterial with a combination of high tensile strength and high elasticity, and it has long been suggested to belong to liquid crystalline materials. However, a satisfactory liquid crystal description for the mechanical properties of the dragline is still missing. To solve the long existing problem, we generalized the Maier-Saupe theory of nematics to construct a liquid crystal model of the deformation mechanism of the dragline silk. We show that the remarkable elasticity of the dragline can be understood as the isotropic-nematic phase transition of the chain network with the beginning of the transition corresponding to the yield point. The calculated curve fits well with the measurements and the yield point is obtained self-consistently within our framework. The present theory can also qualitatively account for the drop of stress in supercontracted spider silk. All these comprehensive agreements between theory and experiments strongly indicate the dragline to belong to liquid crystal materials.
Liquid crystal interfaces: Experiments, simulations and biosensors

Science.gov (United States)

Popov, Piotr

Interfacial phenomena are ubiquitous and extremely important in various aspects of biological and industrial processes. For example, many liquid crystal applications start by alignment with a surface. The underlying mechanisms of the molecular organization of liquid crystals at an interface are still under intensive study and continue to be important to the display industry in order to develop better and/or new display technology. My dissertation research has been devoted to studying how complex liquid crystals can be guided to organize at an interface, and to using my findings to develop practical applications. Specifically, I have been working on developing biosensors using liquid-crystal/surfactant/lipid/protein interactions as well as the alignment of low-symmetry liquid crystals for potential new display and optomechanical applications. The biotechnology industry needs better ways of sensing biomaterials and identifying various nanoscale events at biological interfaces and in aqueous solutions. Sensors in which the recognition material is a liquid crystal naturally connects the existing knowledge and experience of the display and biotechnology industries together with surface and soft matter sciences. This dissertation thus mainly focuses on the delicate phenomena that happen at liquid interfaces. In the introduction, I start by defining the interface and discuss its structure and the relevant interfacial forces. I then introduce the general characteristics of biosensors and, in particular, describe the design of biosensors that employ liquid crystal/aqueous solution interfaces. I further describe the basic properties of liquid crystal materials that are relevant for liquid crystal-based biosensing applications. In CHAPTER 2, I describe the simulation methods and experimental techniques used in this dissertation. In CHAPTER 3 and CHAPTER 4, I present my computer simulation work. CHAPTER 3 presents insight of how liquid crystal molecules are aligned by
Thermotropic Ionic Liquid Crystals

Science.gov (United States)

Axenov, Kirill V.; Laschat, Sabine

2011-01-01

The last five years’ achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed. PMID:28879986
Thermotropic Ionic Liquid Crystals

Directory of Open Access Journals (Sweden)

Sabine Laschat

2011-01-01

Full Text Available The last five years’ achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed.
Thermotropic Ionic Liquid Crystals.

Science.gov (United States)

Axenov, Kirill V; Laschat, Sabine

2011-01-14

The last five years' achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed.
Thermotropic Ionic Liquid Crystals

OpenAIRE

Axenov, Kirill V.; Laschat, Sabine

2011-01-01

The last five years’ achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed.
Optical Study of Liquid Crystal Doped with Multiwalled Carbon Nanotube

Science.gov (United States)

Gharde, Rita A.; Thakare, Sangeeta Y.

2014-11-01

Liquid crystalline materials have been useful for display devices i.e watches, calculators, automobile dashboards, televisions, multi media projectors etc. as well as in electro tunable lasers, optical fibers and lenses. Carbon nanotube is chosen as the main experimental factor in this study as it has been observed that Carbon Nano Tube influence the existing properties of liquid crystal host and with the doping of CNT can enhance1 the properties of LC. The combination of carbon nanotube (CNT) and liquid crystal (LC) materials show considerable interest in the scientific community due to unique physical properties of CNT in liquid crystal. Dispersion of CNTs in LCs can provide us a cheap, simple, versatile and effective means of controlling nanotube orientation on macroscopic scale with no restrictions on nanotube type. LCs have the long range orientational order rendering them to be anisotropic phases. If CNTs can be well dispersed in LC matrix, they will align with their long axes along the LC director to minimize distortions of the LC director field and the free energy. In this paper, we doped liquid crystal (Cholesteryl Nonanoate) by a small amount of multiwall carbon nanotube 0.05% and 0.1% wt. We found that by adding carbon nanotube to liquid crystals the melting point of the mixture is decreased but TNI is increased. It has been also observed that with incereas in concentration of carbon nanotube into liquid crystal shows conciderable effect on LC. The prepared samples were characterized using various techniques to study structural, thermal and optical properties i.e PMS, FPSS, UV-Vis spectroscopy, FT-IR measurements, and DTA.
X-ray diffraction topography observations of the core in Bi12SiO20 crystals doped with Mn

International Nuclear Information System (INIS)

Milenov, T.I.; Botev, P.A.; Rafailov, P.M.; Gospodinov, M.M.

2004-01-01

The core region in a bismuth silicate--Bi 12 SiO 20 (BSO) crystal doped with Mn was examined by X-ray double-crystal diffraction topography. Specific features were observed in the topographies as lines and contrast differences that point to defects occupying the central part of the crystal. We discuss the nature of these defects and propose an explanation in terms of stacking faults arranged in different structures
Phase modulation due to crystal diffraction by ptychographic imaging

Science.gov (United States)

Civita, M.; Diaz, A.; Bean, R. J.; Shabalin, A. G.; Gorobtsov, O. Yu.; Vartanyants, I. A.; Robinson, I. K.

2018-03-01

Solving the phase problem in x-ray crystallography has occupied a considerable scientific effort in the 20th century and led to great advances in structural science. Here we use x-ray ptychography to demonstrate an interference method which measures the phase of the beam transmitted through a crystal, relative to the incoming beam, when diffraction takes place. The observed phase change of the direct beam through a small gold crystal is found to agree with both a quasikinematical model and full dynamical theories of diffraction. Our discovery of a diffraction contrast mechanism will enhance the interpretation of data obtained from crystalline samples using the ptychography method, which provides some of the most accurate x-ray phase-contrast images.
Nonlinear and quantum optics with liquid crystals

International Nuclear Information System (INIS)

Lukishova, Svetlana G

2014-01-01

Thermotropic liquid crystals' usual application is display technology. This paper describes experiments on light interaction with pure and doped liquid crystals under for these materials unconventional incident light powers: (1) under high-power laser irradiation, and (2) at the single-photon level. In (1), I will outline several nonlinear optical effects under high-power, nanosecond laser irradiation which should be taken into account in the design of lasers with liquid crystal components and in fabrication of optical power limiters based on liquid crystals: (1.1) athermal helical pitch dilation and unwinding of cholesteric mirrors (both in free space and inside laser resonators); (1.2) some pitfalls in measurements of refractive nonlinearity using z-scan technique under two-photon or linear absorption of liquids; (1.3) the first observation of thermal lens effects in liquid crystals under several-nanosecond, low-pulse-repetition rate (2-10 Hz) laser irradiation in the presence of two-photon absorption; (1.4) feedback-free kaleidoscope of patterns (hexagons, stripes, etc.) in dye-doped liquid crystals. In (2), at the single-photon level, it will be shown that with a proper selection of liquid crystals and a single-emitter dopant spectral range, liquid crystal structures can be used to control emitted single photons (both polarization and count rate). The application of the latter research is absolutely secure quantum communication with polarization coding of information. In particular, in (2.1), definite handedness, circular polarized cholesteric microcavity resonance in quantum dot fluorescence is reported. In (2.2), definite linear polarization of single (antibunched) photons from single-dye-molecules in planar-aligned nematic host is discussed. In (2.3), some results on photon antibunching from NV-color center in nanodiamond in liquid crystal host and circularly polarized fluorescence of definite handedness from nanocrystals doped with trivalent ions of
Key Developments in Ionic Liquid Crystals

OpenAIRE

Fernandez, A.A.; Kouwer, P.H.J.

2016-01-01

Ionic liquid crystals are materials that combine the classes of liquid crystals and ionic liquids. The first one is based on the multi-billion-dollar flat panel display industry, whilst the latter quickly developed in the past decades into a family of highly-tunable non-volatile solvents. The combination yields materials with a unique set of properties, but also with many challenges ahead. In this review, we provide an overview of the key concepts in ionic liquid crystals, particularly from a...
Lyotropic Liquid Crystal Phases from Anisotropic Nanomaterials

Directory of Open Access Journals (Sweden)

Ingo Dierking

2017-10-01

Full Text Available Liquid crystals are an integral part of a mature display technology, also establishing themselves in other applications, such as spatial light modulators, telecommunication technology, photonics, or sensors, just to name a few of the non-display applications. In recent years, there has been an increasing trend to add various nanomaterials to liquid crystals, which is motivated by several aspects of materials development. (i addition of nanomaterials can change and thus tune the properties of the liquid crystal; (ii novel functionalities can be added to the liquid crystal; and (iii the self-organization of the liquid crystalline state can be exploited to template ordered structures or to transfer order onto dispersed nanomaterials. Much of the research effort has been concentrated on thermotropic systems, which change order as a function of temperature. Here we review the other side of the medal, the formation and properties of ordered, anisotropic fluid phases, liquid crystals, by addition of shape-anisotropic nanomaterials to isotropic liquids. Several classes of materials will be discussed, inorganic and mineral liquid crystals, viruses, nanotubes and nanorods, as well as graphene oxide.
Crystallization and preliminary X-ray diffraction analysis of rat autotaxin

International Nuclear Information System (INIS)

Day, Jacqueline E.; Hall, Troii; Pegg, Lyle E.; Benson, Timothy E.; Hausmann, Jens; Kamtekar, Satwik

2010-01-01

Autotaxin (ATX), a pyrophosphatase/phosphodiesterase enzyme, is a promising drug target for many indications and is only distantly related to enzymes of previously determined structure. Here, the cloning, expression, purification, crystallization and preliminary diffraction analysis of ATX are reported. Rat autotaxin has been cloned, expressed, purified to homogeneity and crystallized via hanging-drop vapour diffusion using PEG 3350 as precipitant and ammonium iodide and sodium thiocyanate as salts. The crystals diffracted to a maximum resolution of 2.05 Å and belonged to space group P1, with unit-cell parameters a = 53.8, b = 63.3, c = 70.5 Å, α = 98.8, β = 106.2, γ = 99.8°. Preliminary X-ray diffraction analysis indicated the presence of one molecule per asymmetric unit, with a solvent content of 47%
Crystal diffraction lens for medical imaging

International Nuclear Information System (INIS)

Smither, R. K.; Roa, D. E.

2000-01-01

A crystal diffraction lens for focusing energetic gamma rays has been developed at Argonne National Laboratory for use in medical imaging of radioactivity in the human body. A common method for locating possible cancerous growths in the body is to inject radioactivity into the blood stream of the patient and then look for any concentration of radioactivity that could be associated with the fast growing cancer cells. Often there are borderline indications of possible cancers that could be due to statistical functions in the measured counting rates. In order to determine if these indications are false or real, one must resort to surgical means and take tissue samples in the suspect area. They are developing a system of crystal diffraction lenses that will be incorporated into a 3-D imaging system with better sensitivity (factors of 10 to 100) and better spatial resolution (a few mm in both vertical and horizontal directions) than most systems presently in use. The use of this new imaging system will allow one to eliminate 90% of the false indications and both locate and determine the size of the cancer with mm precision. The lens consists of 900 single crystals of copper, 4 mm x 4 mm on a side and 2--4 mm thick, mounted in 13 concentric rings
Crystallization and diffraction analysis of thioredoxin reductase from Streptomyces coelicolor

International Nuclear Information System (INIS)

Koháryová, Michaela; Brynda, Jiří; Řezáčová, Pavlína; Kollárová, Marta

2011-01-01

Thioredoxin reductase from S. coelicolor was crystallized and diffraction data were collected to 2.4 Å resolution. Thioredoxin reductases are homodimeric flavoenzymes that catalyze the transfer of electrons from NADPH to oxidized thioredoxin substrate. Bacterial thioredoxin reductases represent a promising target for the development of new antibiotics. Recombinant thioredoxin reductase TrxB from Streptomyces coelicolor was crystallized using the hanging-drop vapour-diffusion method. X-ray diffraction data were collected from cryocooled crystals to 2.4 Å resolution using a synchrotron-radiation source. The crystals belonged to the primitive monoclinic space group P2 1 , with unit-cell parameters a = 82.9, b = 60.6, c = 135.4 Å, α = γ = 90.0, β = 96.5°
Liquid crystal true 3D displays for augmented reality applications

Science.gov (United States)

Li, Yan; Liu, Shuxin; Zhou, Pengcheng; Chen, Quanming; Su, Yikai

2018-02-01

Augmented reality (AR) technology, which integrates virtual computer-generated information into the real world scene, is believed to be the next-generation human-machine interface. However, most AR products adopt stereoscopic 3D display technique, which causes the accommodation-vergence conflict. To solve this problem, we have proposed two approaches. The first is a multi-planar volumetric display using fast switching polymer-stabilized liquid crystal (PSLC) films. By rapidly switching the films between scattering and transparent states while synchronizing with a high-speed projector, the 2D slices of a 3D volume could be displayed in time sequence. We delved into the research on developing high-performance PSLC films in both normal mode and reverse mode; moreover, we also realized the demonstration of four-depth AR images with correct accommodation cues. For the second approach, we realized a holographic AR display using digital blazed gratings and a 4f system to eliminate zero-order and higher-order noise. With a 4k liquid crystal on silicon device, we achieved a field of view (FOV) of 32 deg. Moreover, we designed a compact waveguidebased holographic 3D display. In the design, there are two holographic optical elements (HOEs), each of which functions as a diffractive grating and a Fresnel lens. Because of the grating effect, holographic 3D image light is coupled into and decoupled out of the waveguide by modifying incident angles. Because of the lens effect, the collimated zero order light is focused at a point, and got filtered out. The optical power of the second HOE also helps enlarge FOV.
Electrotransport in ionic crystals: Pt. 1. Application of liquid electrolyte theory

International Nuclear Information System (INIS)

Janek, J.

1994-01-01

Transport of matter and charge in ionic crystals is only possible by the existence of irregular structure elements (defects) which are often charged relative to the crystal lattice. A comparison between the transport behaviour of a crystalline matrix containing such charged defects and a liquid electrolyte containing dissolved ions shows a lot of similarities. As is well known the transport properties of liquid electrolytes are strongly affected by interactions between the dissolved ions. We have applied the well elaborated concept of mixed electrolytes by Onsager and Fuoss which was originally devoted to liquid electrolytes to ionic crystals containing charged point defects. The equations of Onsager and Fuoss allow in principle the calculation of the concentration dependence of the phenomenological transport coefficients L ij of all charge carriers of n-component electrolytes. We will use these equations to predict the transport behaviour of ionic crystals containing differently charged point defects. As examples we have calculated transport coefficients for electrolyte systems which can be regarded as models for the transition metal oxides Co 1-δ O and Cu 2-δ O. One major result concerns the magnitude of the cross effect between the ionic and electronic fluxes in those materials. The implications of these results with respect to experimental observations are discussed. (orig.)
Nanoscopic Manipulation and Imaging of Liquid Crystals

Energy Technology Data Exchange (ETDEWEB)

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

2014-02-04

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

Fast switchable ferroelectric liquid crystal gratings with two electro-optical modes

International Nuclear Information System (INIS)

Ma, Ying; Srivastava, A. K.; Chigrinov, V. G.; Kwok, H.-S.; Wang, Xiaoqian

2016-01-01

In this article, we reveal a theoretical and experimental illustration of the Ferroelectric liquid crystal (FLC) grating fabricated by mean of patterned alignment based on photo-alignment. The complexity related to the mismatching of the predefined alignment domains on the top and bottom substrate has been avoided by incorporating only one side photo aligned substrate while the other substrate does not have any alignment layer. Depending on the easy axis in the said alignment domains and the azimuth plane of the impinging polarized light, the diffracting element can be tuned in two modes i.e. DIFF/OFF switchable and DIFF/TRANS switchable modes, which can be applied to different applications. The diffraction profile has been illustrated theoretically that fits well with the experimental finding and thus the proposed diffraction elements with fast response time and high diffraction efficiency could find application in many modern devices.
Liquid crystals in biotribology synovial joint treatment

CERN Document Server

Ermakov, Sergey; Eismont, Oleg; Nikolaev, Vladimir

2016-01-01

This book summarizes the theoretical and experimental studies confirming the concept of the liquid-crystalline nature of boundary lubrication in synovial joints. It is shown that cholesteric liquid crystals in the synovial liquid play a significant role in the mechanism of intra-articular friction reduction. The results of structural, rheological and tribological research of the creation of artificial synovial liquids - containing cholesteric liquid crystals in natural synovial liquids - are described. These liquid crystals reproduce the lubrication properties of natural synovia and provide a high chondroprotective efficiency. They were tested in osteoarthritis models and in clinical practice.
Structural peculiarities and point defects of bulk-ZnO single crystals

International Nuclear Information System (INIS)

Kaurova, I.A.; Kuz’micheva, G.M.; Rybakov, V.B.; Cousson, A.; Gayvoronsky, V.Ya.

2014-01-01

Highlights: • ZnO single crystals of different color were grown by the hydrothermal method. • Point defects in ZnO have been firstly investigated by neutron diffraction. • Presence of additional reflections caused by kinetic growth effects was revealed. • The relationship between the color and zinc and oxygen vacancies was found. • Photoinduced variation of transmittance versus the CW laser intensity was analyzed. - Abstract: ZnO single crystals are related to promising direct wide band gap semiconductor materials belonging to the A II B VI type of compounds with wurtzite structure. “Unintentional” n-type conductivity in ZnO may be caused by zinc and oxygen vacancies, and interstitial zinc atoms. To date, the comprehensive structural investigation and analysis of point defects in ZnO is absent in literature. Green, light green and almost colorless ZnO single crystals grown by the hydrothermal method in concentrated alkali solutions 4M(KOH) + 1M(LiOH) + 0.1M(NH 4 OH) on monohedral seeds [0 0 0 1] at crystallization temperatures in the range of 330–350 °C and pressures in the range of 30–50 MPa have been firstly investigated by neutron diffraction. It was revealed the presence of additional reflections (∼12–∼16%) for all the crystals caused by kinetic growth effects that give grounds to assign them to the space group P3 rather than to P6 3 mc. Analysis of the refined compositions together with the color of ZnO crystals does not rule out the relationship between the color and vacancies in the zinc and oxygen positions whose concentration decreases with the discoloration of the samples. The analysis of the photoinduced variation of the total and on-axis transmittance versus the CW laser intensity showed that the colored samples have profound deep defects related to oxygen vacancies
Thermalization calorimetry: A simple method for investigating glass transition and crystallization of supercooled liquids

DEFF Research Database (Denmark)

Jakobsen, Bo; Sanz, Alejandro; Niss, Kristine

2016-01-01

and their crystallization, e.g., for locating the glass transition and melting point(s), as well as for investigating the stability against crystallization and estimating the relative change in specific heat between the solid and liquid phases at the glass transition......We present a simple method for fast and cheap thermal analysis on supercooled glass-forming liquids. This “Thermalization Calorimetry” technique is based on monitoring the temperature and its rate of change during heating or cooling of a sample for which the thermal power input comes from heat...
Biaxial nematic liquid crystals theory, simulation and experiment

CERN Document Server

Luckhurst, Geoffrey R

2015-01-01

Liquid Crystals are a state of matter that have properties between those of conventional liquid and those of a solid crystal. Thermotropic liquid crystals react to changes in temperature or, in some cases, pressure. The reaction of lyotropic liquid crystals, which are used in the manufacture of soaps and detergents, depends on the type of solvent they are mixed with. Since the accidental discovery of the chiral nematic (ordered) phase in 1888 many liquid crystal phases have been found, sometimes by chance and sometimes by design. The existence of one such phase was predicted by Freiser in 197
Crystallized solids characterization by X-ray diffraction

International Nuclear Information System (INIS)

Broll, N.

1996-01-01

This work deals with the crystallized solids characterization by X-ray diffraction. The powders diffraction principle is described. Then are given the different powders diffraction experimental methods. An X-ray diffraction device is essentially constituted of three parts: the X-rays source, the sample and the detector. The source is usually constituted by an X-rays tube whereas the sample can be fixed on a photographic chamber or put on a goniometer. The different photographic chambers which can be used (Debye-Scherrer, Seeman-Bohlin and Guinier) are described. The powders diffractometer the most used is a Bragg-Brentano focusing diffractometer because it allows to obtain very sharp spectral lines and an important diffracted intensity. The detectors which are the mainly used are the scintillation counters. The most important use in powders diffractometry is the identification of the different phases of a sample. The phases identification consists to compare the unknown sample spectrum at those of standard materials indexed until now. Two methods exist at present. They are explained and their limits in the phases search are given. Another use of the X-ray diffraction is the quantitative analysis. It consists to determine the concentrations of each crystal phases of a sample. The principles of these quantitative methods are given. The lattice parameters of a polycrystal material can be determined from its X-ray pattern too with a very high precision. The way to index powders patterns is given. The residual stresses of materials can also be estimated. The principle of this measured method is explained. It is at last possible to study from an X-ray pattern, the material grain orientations during the different steps of preparation and working. (O.M.). 13 refs., 19 figs., 1 tab
Crystallization and diffraction analysis of β-N-acetylhexosaminidase from Aspergillus oryzae

International Nuclear Information System (INIS)

Vaněk, Ondřej; Brynda, Jiří; Hofbauerová, Kateřina; Kukačka, Zdeněk; Pachl, Petr; Bezouška, Karel; Řezáčová, Pavlína

2011-01-01

The fungal β-N-acetylhexosaminidase from A. oryzae was crystallized and diffraction data were collected from two crystal forms to 3.2 and 2.4 Å resolution, respectively. Fungal β-N-acetylhexosaminidases are enzymes that are used in the chemoenzymatic synthesis of biologically interesting oligosaccharides. The enzyme from Aspergillus oryzae was produced and purified from its natural source and crystallized using the hanging-drop vapour-diffusion method. Diffraction data from two crystal forms (primitive monoclinic and primitive tetragonal) were collected to resolutions of 3.2 and 2.4 Å, respectively. Electrophoretic and quantitative N-terminal protein-sequencing analyses confirmed that the crystals are formed by a complete biologically active enzyme consisting of a glycosylated catalytic unit and a noncovalently attached propeptide
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.
Ultra-fast solid state electro-optical modulator based on liquid crystal polymer and liquid crystal composites

Energy Technology Data Exchange (ETDEWEB)

Ouskova, Elena; Sio, Luciano De, E-mail: luciano@beamco.com; Vergara, Rafael; Tabiryan, Nelson [Beam Engineering for Advanced Measurements Company, Winter Park, Florida 32789 (United States); White, Timothy J.; Bunning, Timothy J. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433-7707 (United States)

2014-12-08

A different generation of polymer-dispersed liquid crystals (PDLCs) based on a liquid crystalline polymer host is reported wherein the fluid behavior of the reactive mesogenic monomer is an enabler to concentration windows (liquid crystal polymer/liquid crystal) (and subsequent morphologies) not previously explored. These liquid crystal (LC) polymer/LC composites, LCPDLCs, exhibit excellent optical and electro-optical properties with negligible scattering losses in both the ON and OFF states. These systems thus have application in systems where fast phase modulation of optical signal instead of amplitude control is needed. Polarized optical microscopy and high resolution scanning electron microscopy confirm a bicontinuous morphology composed of aligned LC polymer coexisting with a phase separated LC fluid. Operating voltages, switching times, and spectra of LCPDLCs compare favourably to conventional PDLC films. The LCPDLCs exhibit a low switching voltage (4–5 V/μm), symmetric and submillisecond (200 μs) on/off response times, and high transmission in both the as formed and switched state in a phase modulation geometry.
Asymmetric flavone-based liquid crystals: synthesis and properties

Energy Technology Data Exchange (ETDEWEB)

Timmons, Daren J. [Department of Chemistry, Virginia Military Institute, Lexington, VA, USA; Jordan, Abraham J. [Department of Chemistry, Virginia Military Institute, Lexington, VA, USA; Kirchon, Angelo A. [Department of Chemistry, Virginia Military Institute, Lexington, VA, USA; Murthy, N. Sanjeeva [New Jersey Center for Biomaterials, Rutgers, The State University of New Jersey, Piscataway, NJ, USA; Siemers, Troy J. [Department of Applied Mathematics, Virginia Military Institute, Lexington, VA, USA; Harrison, Daniel P. [Department of Chemistry, Virginia Military Institute, Lexington, VA, USA; Slebodnick, Carla [Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA

2017-02-01

A series of flavones (n-F) substituted at the 4', and 6 positions was prepared, characterised by NMR (1H,13C), HRMS, and studied for liquid crystal properties. The 4'-alkoxy,6-methoxyflavones (4-F–16-F) exhibit varying ranges of nematic and smectic A phases as evidenced by polarised optical microscopy and differential scanning calorimetry (DSC). As the tail length is increased, the smectic phase becomes more prevalent. Smectic phases for (8-F–16-F) were further analysed by powder X-ray diffraction (XRD), and the rate of structural transformations was explored by combined DSC/XRD studies. Flavonol 6-F–OH was also prepared but no mesogenic behaviour was observed. The molecular structures of 6-F and 6-F–OH were determined by single-crystal XRD and help to explain the differences in material properties. Additionally, fluorescence and electrochemical studies were conducted on solutions of n-F.
Characterization of a polychromatic neutron beam diffracted by pyrolytic graphite crystals

CERN Document Server

Byun, S H; Choi, H D

2002-01-01

The beam spectrum for polychromatic neutrons diffracted by pyrolytic graphite crystals was characterized. The theoretical beam spectrum was obtained using the diffraction model for a mosaic crystal. The lattice vibration effects were included in the calculation using the reported vibration amplitude of the crystal and the measured time-of-flight spectra in the thermal region. The calculated beam spectrum was compared with the results obtained in the absence of thermal motion. The lattice vibration effects became more important for the higher diffraction orders and a large decrease in the neutron flux induced by the vibrations was identified in the epithermal region. The validity of the beam spectrum was estimated by comparing with the effective quantities determined from prompt gamma-ray measurements and Cd-ratios measured both for 1/nu and non-1/nu nuclides.
NMR spectroscopy using liquid crystal solvents

CERN Document Server

Emsley, JW

2013-01-01

NMR Spectroscopy using Liquid Crystal Solvents covers the importance of using a liquid crystal solvent in NMR to derive nuclear dipolar spin-spin coupling constants. This book is composed of ten chapters, and begins with a brief description of the features and benefits of liquid crystal in NMR spectroscopic analysis. The succeeding chapters deal with the mode of operation of nuclear spin Hamiltonian for partially oriented molecules and the analysis of NMR spectra of partially oriented molecules, as well as the determination of rigid molecule structure. These topics are followed by discussions
Lead(ii) soaps: crystal structures, polymorphism, and solid and liquid mesophases.

Science.gov (United States)

Martínez-Casado, F J; Ramos-Riesco, M; Rodríguez-Cheda, J A; Redondo-Yélamos, M I; Garrido, L; Fernández-Martínez, A; García-Barriocanal, J; da Silva, I; Durán-Olivencia, M; Poulain, A

2017-07-05

The long-chain members of the lead(ii) alkanoate series or soaps, from octanoate to octadecanoate, have been thoroughly characterized by means of XRD, PDF analysis, DSC, FTIR, ssNMR and other techniques, in all their phases and mesophases. The crystal structures at room temperature of all of the members of the series are now solved, showing the existence of two polymorphic forms in the room temperature crystal phase, different to short and long-chain members. Only nonanoate and decanoate present both forms, and this polymorphism is proven to be monotropic. At higher temperature, these compounds present a solid mesophase, defined as rotator, a liquid crystal phase and a liquid phase, all of which have a similar local arrangement. Since some lead(ii) soaps appear as degradation compounds in oil paintings, the solved crystal structures of lead(ii) soaps can now be used as fingerprints for their detection using X-ray diffraction. Pair distribution function analysis on these compounds is very similar in the same phases and mesophases for the different members, showing the same short range order. This observation suggests that this technique could also be used in the detection of these compounds in disordered phases or in the initial stages of formation in paintings.
Computer modeling of liquid crystals

International Nuclear Information System (INIS)

Al-Barwani, M.S.

1999-01-01

In this thesis, we investigate several aspects of the behaviour of liquid crystal molecules near interfaces using computer simulation. We briefly discuss experiment, theoretical and computer simulation studies of some of the liquid crystal interfaces. We then describe three essentially independent research topics. The first of these concerns extensive simulations of a liquid crystal formed by long flexible molecules. We examined the bulk behaviour of the model and its structure. Studies of a film of smectic liquid crystal surrounded by vapour were also carried out. Extensive simulations were also done for a long-molecule/short-molecule mixture, studies were then carried out to investigate the liquid-vapour interface of the mixture. Next, we report the results of large scale simulations of soft-spherocylinders of two different lengths. We examined the bulk coexistence of the nematic and isotropic phases of the model. Once the bulk coexistence behaviour was known, properties of the nematic-isotropic interface were investigated. This was done by fitting order parameter and density profiles to appropriate mathematical functions and calculating the biaxial order parameter. We briefly discuss the ordering at the interfaces and make attempts to calculate the surface tension. Finally, in our third project, we study the effects of different surface topographies on creating bistable nematic liquid crystal devices. This was carried out using a model based on the discretisation of the free energy on a lattice. We use simulation to find the lowest energy states and investigate if they are degenerate in energy. We also test our model by studying the Frederiks transition and comparing with analytical and other simulation results. (author)
Key Developments in Ionic Liquid Crystals.

Science.gov (United States)

Alvarez Fernandez, Alexandra; Kouwer, Paul H J

2016-05-16

Ionic liquid crystals are materials that combine the classes of liquid crystals and ionic liquids. The first one is based on the multi-billion-dollar flat panel display industry, whilst the latter quickly developed in the past decades into a family of highly-tunable non-volatile solvents. The combination yields materials with a unique set of properties, but also with many challenges ahead. In this review, we provide an overview of the key concepts in ionic liquid crystals, particularly from a molecular perspective. What are the important molecular parameters that determine the phase behavior? How should they be introduced into the molecules? Finally, which other tools does one have to realize specific properties in the material?
Key Developments in Ionic Liquid Crystals

Directory of Open Access Journals (Sweden)

Alexandra Alvarez Fernandez

2016-05-01

Full Text Available Ionic liquid crystals are materials that combine the classes of liquid crystals and ionic liquids. The first one is based on the multi-billion-dollar flat panel display industry, whilst the latter quickly developed in the past decades into a family of highly-tunable non-volatile solvents. The combination yields materials with a unique set of properties, but also with many challenges ahead. In this review, we provide an overview of the key concepts in ionic liquid crystals, particularly from a molecular perspective. What are the important molecular parameters that determine the phase behavior? How should they be introduced into the molecules? Finally, which other tools does one have to realize specific properties in the material?
Multiple x-ray diffraction applied to the study of crystal impurities

International Nuclear Information System (INIS)

Cardoso, L.P.

1983-06-01

The x-ray multiple diffraction technique is used in the study of impurities concentration and localization in the crystal lattice, implemented with the fundamental observation that the impurities cannot be distributed with the same spatial group symmetry of the crystal. This fact could introduce scattered intensity in the crystal reciprocal lattice forbidden nodes. This effect was effectively observed in multiple diffraction diagrams, where a reinforcement of the scattered intensity in the pure crystal is produced, when choosing conveniently the involved reflections. The reflectivity theory was developed in the kinematic case, which take into account the scattering by the impurities atoms, and the analysis showed that, in the first approximation, the impurities can influence both in the allowed and forbidden positions for the pure crystal. (L.C.J.A.)
X-ray diffraction from ideal mosaic crystals in external fields of certain types. I. Atomic displacements and the corresponding diffraction patterns

International Nuclear Information System (INIS)

Treushnikov, E.N.

2000-01-01

The problem of the theoretical description of X-ray diffraction from ideal mosaic crystals under the effect of various external fields has been formulated. Electric, magnetic, electromagnetic, and acoustic perturbations are considered. The atomic displacements in crystals under the effect of external fields and the types of the corresponding diffraction patterns are analyzed for various types of perturbations. The crystal classes are determined in which atomic displacements can be recorded experimentally. Diffraction patterns formed under the effect of various external factors are considered on the basis of the derived dependence of the structure factor on the characteristics of an applied force field
New Pyrazolium Salts as a Support for Ionic Liquid Crystals and Ionic Conductors.

Science.gov (United States)

Pastor, María Jesús; Sánchez, Ignacio; Campo, José A; Schmidt, Rainer; Cano, Mercedes

2018-04-03

Ionic liquid crystals (ILCs) are a class of materials that combine the properties of liquid crystals (LCs) and ionic liquids (ILs). This type of materials is directed towards properties such as conductivity in ordered systems at different temperatures. In this work, we synthesize five new families of ILCs containing symmetrical and unsymmetrical substituted pyrazolium cations, with different alkyl long-chains, and anions such as Cl - , BF₄ - , ReO₄ - , p -CH₃-₆H₄SO₃ - (PTS) and CF₃SO₃ - (OTf). We study their thermal behavior by polarized light optical microscopy (POM) and differential scanning calorimetry (DSC). All of them, except those with OTf as counteranion, show thermotropic mesomorphism. The observations by POM reveal textures of lamellar mesophases. Those agree with the arrangement observed in the X-ray crystal structure of [H₂pz R(4),R(4) ][ReO₄]. The nature of the mesophases is also confirmed by variable temperature powder X-ray diffraction. On the other hand, the study of the dielectric properties at variable temperature in mesomorphic (Cl - and BF₄ - ) and non-mesomorphic (OTf) salts indicates that the supramolecular arrangement of the mesophase favors a greater ionic mobility and therefore ionic conductivity.
Alignment structures in ferroelectric liquid crystals

Energy Technology Data Exchange (ETDEWEB)

Islam, N.U

1998-07-01

Although for many years liquid crystals were of purely scientific interest, they have now become ubiquitous in everyday life. The use of the nematic liquid crystal phase in flat panel display applications has been the main factor in this popularity. However, with the advent of the SuperTwist Nematic (STN) device, the limits to which this phase could be exploited for display applications was perhaps reached. With the discovery by Clark et al. of the Surface Stabilised Ferroelectric Liquid Crystal (SSFLC) configuration, the possibility arose of using chiral smectic liquid crystals to create large area, passively addressed, fast switching, flat panel displays. Unfortunately, the structures that form within smectic liquid crystals, and the dynamics of the switching within these, are still not fully understood. In this thesis we address the former of these, making a detailed the study of the structures that form within tilted smectic liquid crystal devices. We present here the first complete theoretical and experimental study of various different ferroelectric liquid crystal materials, where we employed theoretical models based on a simple set of assumptions to understand the behaviour of a set of increasingly complex experimental systems. We started with the simplest of these, Freely Suspended Smectic Films (FSSFs) and then worked with progressively more realistic systems in the form of homeotropically, and later, homogeneously aligned liquid crystal cells. The equilibrium structures that form get particularly complex in the last case, taking the form of tilted and chevron layering structures. In each of these cases, the predictions of the modelling are compared with our experimental results. Further, we present here the first model of the chevron cusp that seeks to include the effects of biaxiality in the S{sub C} phase. We also present a model that seeks to analyse the stability of the chevron layering structure and its relationship with tilted layers. This includes

Alignment structures in ferroelectric liquid crystals

International Nuclear Information System (INIS)

Islam, N.U.

1998-01-01

Although for many years liquid crystals were of purely scientific interest, they have now become ubiquitous in everyday life. The use of the nematic liquid crystal phase in flat panel display applications has been the main factor in this popularity. However, with the advent of the SuperTwist Nematic (STN) device, the limits to which this phase could be exploited for display applications was perhaps reached. With the discovery by Clark et al. of the Surface Stabilised Ferroelectric Liquid Crystal (SSFLC) configuration, the possibility arose of using chiral smectic liquid crystals to create large area, passively addressed, fast switching, flat panel displays. Unfortunately, the structures that form within smectic liquid crystals, and the dynamics of the switching within these, are still not fully understood. In this thesis we address the former of these, making a detailed the study of the structures that form within tilted smectic liquid crystal devices. We present here the first complete theoretical and experimental study of various different ferroelectric liquid crystal materials, where we employed theoretical models based on a simple set of assumptions to understand the behaviour of a set of increasingly complex experimental systems. We started with the simplest of these, Freely Suspended Smectic Films (FSSFs) and then worked with progressively more realistic systems in the form of homeotropically, and later, homogeneously aligned liquid crystal cells. The equilibrium structures that form get particularly complex in the last case, taking the form of tilted and chevron layering structures. In each of these cases, the predictions of the modelling are compared with our experimental results. Further, we present here the first model of the chevron cusp that seeks to include the effects of biaxiality in the S C phase. We also present a model that seeks to analyse the stability of the chevron layering structure and its relationship with tilted layers. This includes an
X-ray and neutron single crystal diffraction on (NH4)3H(SO4)2. II. Refinement of crystal structure of phase II at room temperature

International Nuclear Information System (INIS)

Reehuis, M.; Wozniak, K.; Dominiak, P.; Smirnov, L.S.; Natkaniec, I.; Baranov, A.I.; Dolbinina, V.V.

2006-01-01

The (NH 4 ) 3 H(SO 4 ) 2 is of special interest due to the possible influence of ammonium ions on a series of phase transitions: I => II => III => IV => V => VII. Earlier, the X-ray single crystal diffraction study of phase II of (NH 4 ) 3 H(SO 4 ) 2 showed that the crystal structure of this compound has two crystallographically independent groups of ammonium ions NH 4 (1) and NH 4 (2), but orientational positions of these ammonium ions were not determined exactly. The refinement of NH 4 (1) and NH 4 (2) orientational positions in phase II is carried out with the help of the X-ray and neutron single crystal diffraction study. The analyses of differential Fourier maps of electron charge density and nuclear density point out the possibility of disordering of NH 4 (2) ammonium ions
Purification, crystallization and preliminary X-ray diffraction studies of parakeet (Psittacula krameri) haemoglobin.

Science.gov (United States)

Jaimohan, S M; Naresh, M D; Arumugam, V; Mandal, A B

2009-10-01

Birds often show efficient oxygen management in order to meet the special demands of their metabolism. However, the structural studies of avian haemoglobins (Hbs) are inadequate for complete understanding of the mechanism involved. Towards this end, purification, crystallization and preliminary X-ray diffraction studies have been carried out for parakeet Hb. Parakeet Hb was crystallized as the met form in low-salt buffered conditions after extracting haemoglobin from crude blood by microcentrifugation and purifying the sample by column chromatography. Good-quality crystals were grown from 10% PEG 3350 and a crystal diffracted to about 2.8 A resolution. Preliminary diffraction data showed that the Hb crystal belonged to the monoclinic system (space group C2), with unit-cell parameters a = 110.68, b = 64.27, c = 56.40 A, beta = 109.35 degrees . Matthews volume analysis indicated that the crystals contained a half-tetramer in the asymmetric unit.
Adsorption phenomena and anchoring energy in nematic liquid crystals

CERN Document Server

Barbero, Giovanni

2005-01-01

Despite the large quantity of phenomenological information concerning the bulk properties of nematic phase liquid crystals, little is understood about the origin of the surface energy, particularly the surface, interfacial, and anchoring properties of liquid crystals that affect the performance of liquid crystal devices. Self-contained and unique, Adsorption Phenomena and Anchoring Energy in Nematic Liquid Crystals provides an account of new and established results spanning three decades of research into the problems of anchoring energy and adsorption phenomena in liquid crystals.The book contains a detailed discussion of the origin and possible sources of anchoring energy in nematic liquid crystals, emphasizing the dielectric contribution to the anchoring energy in particular. Beginning with fundamental surface and anchoring properties of liquid crystals and the definition of the nematic phase, the authors explain how selective ion adsorption, dielectric energy density, thickness dependence, and bias voltage...
Liquid crystalline biopolymers: A new arena for liquid crystal research

International Nuclear Information System (INIS)

Rizvi, Tasneem Zahra

2001-07-01

This paper gives a brief introduction to liquid crystals on the basis of biopolymers and reviews literature on liquid crystalline behaviour of biopolymers both in vitro and in vivo in relation to their implications in the fields of biology, medicine and material science. Knowledge in the field of biological liquid crystals is crucial for understanding complex phenomena at supramolecular level which will give information about processes involved in biological organization and function. The understanding of the interaction of theses crystals with electric, magnetic, optical and thermal fields will uncover mechanisms of near quantum-energy detection capabilities of biosystems
Measuring the x-ray resolving power of bent potassium acid phthalate diffraction crystals

International Nuclear Information System (INIS)

Haugh, M. J.; Jacoby, K. D.; Wu, M.; Loisel, G. P.

2014-01-01

This report presents the results from measuring the X-ray resolving power of a curved potassium acid phthalate (KAP(001)) spectrometer crystal using two independent methods. It is part of a continuing effort to measure the fundamental diffraction properties of bent crystals that are used to study various characteristics of high temperature plasmas. Bent crystals like KAP(001) do not usually have the same diffraction properties as corresponding flat crystals. Models that do exist to calculate the effect of bending the crystal on the diffraction properties have simplifying assumptions and their accuracy limits have not been adequately determined. The type of crystals that we measured is being used in a spectrometer on the Z machine at Sandia National Laboratories in Albuquerque, New Mexico. The first technique for measuring the crystal resolving power measures the X-ray spectral line width of the characteristic lines from several metal anodes. The second method uses a diode X-ray source and a double crystal diffractometer arrangement to measure the reflectivity curve of the KAP(001) crystal. The width of that curve is inversely proportional to the crystal resolving power. The measurement results are analyzed and discussed
Measuring the x-ray resolving power of bent potassium acid phthalate diffraction crystals

Energy Technology Data Exchange (ETDEWEB)

Haugh, M. J., E-mail: haughmj@nv.doe.gov; Jacoby, K. D. [National Security Technologies, LLC, Livermore, California 94550 (United States); Wu, M.; Loisel, G. P. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States)

2014-11-15

This report presents the results from measuring the X-ray resolving power of a curved potassium acid phthalate (KAP(001)) spectrometer crystal using two independent methods. It is part of a continuing effort to measure the fundamental diffraction properties of bent crystals that are used to study various characteristics of high temperature plasmas. Bent crystals like KAP(001) do not usually have the same diffraction properties as corresponding flat crystals. Models that do exist to calculate the effect of bending the crystal on the diffraction properties have simplifying assumptions and their accuracy limits have not been adequately determined. The type of crystals that we measured is being used in a spectrometer on the Z machine at Sandia National Laboratories in Albuquerque, New Mexico. The first technique for measuring the crystal resolving power measures the X-ray spectral line width of the characteristic lines from several metal anodes. The second method uses a diode X-ray source and a double crystal diffractometer arrangement to measure the reflectivity curve of the KAP(001) crystal. The width of that curve is inversely proportional to the crystal resolving power. The measurement results are analyzed and discussed.
Chromatic dispersion of liquid crystal infiltrated capillary tubes and photonic crystal fibers

DEFF Research Database (Denmark)

Rasmussen, Per Dalgaard; Lægsgaard, Jesper; Bang, Ole

2006-01-01

We consider chromatic dispersion of capillary tubes and photonic crystal fibers infiltrated with liquid crystals. A perturbative scheme for inclusion of material dispersion of both liquid crystal and the surrounding waveguide material is derived. The method is used to calculate the chromatic...
Liquid crystal-based hydrophone arrays

Science.gov (United States)

Brodzeli, Zourab; Silvestri, Leonardo; Michie, Andrew; Chigrinov, Vladimir G.; Guo, Qi; Pozhidaev, Eugene P.; Kiselev, Alexei D.; Ladouceur, Francois

2012-09-01

We describe a fiber optic hydrophone array system that could be used for underwater acoustic surveillance applications (e.g. military, counter terrorist, and customs authorities in protecting ports and harbors), offshore production facilities or coastal approaches as well as various marine applications. In this paper, we propose a new approach to underwater sonar systems using the voltage-controlled liquid crystals and simple multiplexing method. The proposed method permits measurement of sound under water at multiple points along an optical fiber using the low cost components and standard single mode fiber, without complex interferometric measurement techniques, electronics or demodulation software.
Purification, crystallization and preliminary X-ray diffraction studies of parakeet (Psittacula krameri) haemoglobin

International Nuclear Information System (INIS)

Jaimohan, S. M.; Naresh, M. D.; Arumugam, V.; Mandal, A. B.

2009-01-01

Parakeet (Psittacula krameri) haemoglobin has been purified and crystallized under low salt buffered conditions. Preliminary analysis of the crystal that belonged to monoclinic system (C2) is reported. Birds often show efficient oxygen management in order to meet the special demands of their metabolism. However, the structural studies of avian haemoglobins (Hbs) are inadequate for complete understanding of the mechanism involved. Towards this end, purification, crystallization and preliminary X-ray diffraction studies have been carried out for parakeet Hb. Parakeet Hb was crystallized as the met form in low-salt buffered conditions after extracting haemoglobin from crude blood by microcentrifugation and purifying the sample by column chromatography. Good-quality crystals were grown from 10% PEG 3350 and a crystal diffracted to about 2.8 Å resolution. Preliminary diffraction data showed that the Hb crystal belonged to the monoclinic system (space group C2), with unit-cell parameters a = 110.68, b = 64.27, c = 56.40 Å, β = 109.35°. Matthews volume analysis indicated that the crystals contained a half-tetramer in the asymmetric unit
Liquid crystals for organic transistors (Conference Presentation)

Science.gov (United States)

Hanna, Jun-ichi; Iino, Hiroaki

2016-09-01

Liquid crystals are a new type of organic semiconductors exhibiting molecular orientation in self-organizing manner, and have high potential for device applications. In fact, various device applications have been proposed so far, including photosensors, solar cells, light emitting diodes, field effect transistors, and so on.. However, device performance in those fabricated with liquid crystals is less than those of devices fabricated with conventional materials in spite of unique features of liquid crystals. Here we discuss how we can utilize the liquid crystallinity in organic transistors and how we can overcome conventional non-liquid crystalline organic transistor materials. Then, we demonstrate high performance organic transistors fabricated with a smectic E liquid crystal of Ph-BTBT-10, which show high mobility of over 10cm2/Vs and high thermal durability of over 200oC in OFETs fabricated with its spin-coated polycrystalline thin films.
Chem I Supplement: Liquid Crystals--The Chameleon Chemicals.

Science.gov (United States)

Brown, Glenn H.

1983-01-01

Presents information relevant to everyday life so as to stimulate student interest in the properties of the two basic types of liquid crystals: thermotropic and lyotropic. Describes the applications of liquid crystals to electronics, biomedicine, and polymer science and appraises the future of liquid crystal research. (JM)
Simultaneous X-ray diffraction from multiple single crystals of macromolecules

DEFF Research Database (Denmark)

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

2011-01-01

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

Energy Technology Data Exchange (ETDEWEB)

Palto, S. P. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)], E-mail: palto@online.ru

2006-09-15

A lasing condition is formulated in matrix form for optically anisotropic thin films. Lasing behavior of liquid-crystal slabs is analyzed. In particular, it is shown that if the spatial extent of a liquid crystal slab is much larger than its thickness, then laser emission is feasible not only along the normal to the slab, but also in the entire angular sector. The generated laser light can be observed experimentally as a spot or as concentric rings on a screen. The lowest lasing threshold corresponds to in-plane sliding modes leaking into the substrate. The feedback required for lasing is provided by reflection from the interfaces, rather than edges, of the liquid-crystal slab operating as a planar Fabry-Perot cavity. For cholesteric liquid crystals, it is shown that energy loss to the sliding modes leaking into the substrates and escaping through their edges is a key factor that limits the efficiency of band-edge emission along the normal to the slab.
Dynamic behaviour of the local layer structure of antiferroelectric liquid crystals under a high electric field measured by time-resolved synchrotron x-ray microbeam diffraction

International Nuclear Information System (INIS)

Takahashi, Yumiko; Iida, Atsuo; Takanishi, Yoichi; Ogasawara, Toyokazu; Ishikawa, Ken; Takezoe, Hideo

2001-01-01

The local layer structure response to a triangular electric field in an antiferroelectric liquid crystal cell has been measured using synchrotron X-ray diffraction with 3 ms time resolution and a few μm spatial resolution. The initially coexisting vertical and horizontal chevron structures are irreversibly transformed to the layer structure with a rearranged molecular orientation at the surface (so-called vertical bookshelf structure). After the irreversible transformation, the rearranged layer structure shows a reversible transition between the horizontal chevron (high field, ferroelectric state) and the combination of the modified vertical and horizontal chevron (low field, antiferroelectric state) associated with the field-induced antiferroelectric-ferroelectric transition. The reversible layer structure has a smaller horizontal chevron angle (a few degrees) than that in the initial state (about 17deg). The detailed microbeam diffraction revealed that the layer structure at a low electric field consists of a broad vertical chevron with a small chevron angle and a bent bookshelf in combination with a horizontal chevron, depending on the analyzing position. The stripe texture is related to the modified horizontal chevron structure. (author)
Dynamic behaviour of the local layer structure of antiferroelectric liquid crystals under a high electric field measured by time-resolved synchrotron x-ray microbeam diffraction

Energy Technology Data Exchange (ETDEWEB)

Takahashi, Yumiko [Graduate University for Advanced Studies, Tsukuba, Ibaraki (Japan); Iida, Atsuo [Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan); Takanishi, Yoichi; Ogasawara, Toyokazu; Ishikawa, Ken; Takezoe, Hideo [Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Tokyo (Japan)

2001-05-01

The local layer structure response to a triangular electric field in an antiferroelectric liquid crystal cell has been measured using synchrotron X-ray diffraction with 3 ms time resolution and a few {mu}m spatial resolution. The initially coexisting vertical and horizontal chevron structures are irreversibly transformed to the layer structure with a rearranged molecular orientation at the surface (so-called vertical bookshelf structure). After the irreversible transformation, the rearranged layer structure shows a reversible transition between the horizontal chevron (high field, ferroelectric state) and the combination of the modified vertical and horizontal chevron (low field, antiferroelectric state) associated with the field-induced antiferroelectric-ferroelectric transition. The reversible layer structure has a smaller horizontal chevron angle (a few degrees) than that in the initial state (about 17deg). The detailed microbeam diffraction revealed that the layer structure at a low electric field consists of a broad vertical chevron with a small chevron angle and a bent bookshelf in combination with a horizontal chevron, depending on the analyzing position. The stripe texture is related to the modified horizontal chevron structure. (author)
Higher-order-structure formation in liquid crystal epoxy thermosets investigated by synchrotron radiation-wide-angle X-ray diffraction

International Nuclear Information System (INIS)

Maeda, Rina; Okuhara, Kenta; Nakamura, Akihiro; Hayakawa, Teruaki; Uehara, Yasushi; Motoya, Tsukasa; Nobutoki, Hideharu

2016-01-01

We report the investigation of the mesophase transformations of a liquid crystalline molecule with terminal epoxy groups from the initial stages of curing with a diamine compound. The ordered arrangement of molecules within the smectic layers in the thermoset formed at the end of the curing process was characterized by synchrotron radiation-wide-angle X-ray diffraction (SR-WAXD). Data from this experiment helps us understand the phase transitions from the nematic to smectic phases of curing liquid crystalline epoxies. (author)
Ionic Liquid Crystals: Versatile Materials.

Science.gov (United States)

Goossens, Karel; Lava, Kathleen; Bielawski, Christopher W; Binnemans, Koen

2016-04-27

This Review covers the recent developments (2005-2015) in the design, synthesis, characterization, and application of thermotropic ionic liquid crystals. It was designed to give a comprehensive overview of the "state-of-the-art" in the field. The discussion is focused on low molar mass and dendrimeric thermotropic ionic mesogens, as well as selected metal-containing compounds (metallomesogens), but some references to polymeric and/or lyotropic ionic liquid crystals and particularly to ionic liquids will also be provided. Although zwitterionic and mesoionic mesogens are also treated to some extent, emphasis will be directed toward liquid-crystalline materials consisting of organic cations and organic/inorganic anions that are not covalently bound but interact via electrostatic and other noncovalent interactions.
Electrically Tuned Microwave Devices Using Liquid Crystal Technology

Directory of Open Access Journals (Sweden)

Pouria Yaghmaee

2013-01-01

Full Text Available An overview of liquid crystal technology for microwave and millimeter-wave frequencies is presented. The potential of liquid crystals as reconfigurable materials arises from their ability for continuous tuning with low power consumption, transparency, and possible integration with printed and flexible circuit technologies. This paper describes physical theory and fundamental electrical properties arising from the anisotropy of liquid crystals and overviews selected realized liquid crystal devices, throughout four main categories: resonators and filters, phase shifters and delay lines, antennas, and, finally, frequency-selective surfaces and metamaterials.
Neutron forward diffraction by single crystal prisms

Indian Academy of Sciences (India)

We have derived analytic expressions for the deflection as well as transmitted fraction of monochromatic neutrons forward diffracted by a single crystal prism. In the vicinity of a Bragg reflection, the neutron deflection deviates sharply from that for an amorphous prism, exhibiting three orders of magnitude greater sensitivity to ...

Trapezoidal diffraction grating beam splitters in single crystal diamond

Science.gov (United States)

Kiss, Marcell; Graziosi, Teodoro; Quack, Niels

2018-02-01

Single Crystal Diamond has been recognized as a prime material for optical components in high power applications due to low absorption and high thermal conductivity. However, diamond microstructuring remains challenging. Here, we report on the fabrication and characterization of optical diffraction gratings exhibiting a symmetric trapezoidal profile etched into a single crystal diamond substrate. The optimized grating geometry diffracts the transmitted optical power into precisely defined proportions, performing as an effective beam splitter. We fabricate our gratings in commercially available single crystal CVD diamond plates (2.6mm x 2.6mm x 0.3mm). Using a sputter deposited hard mask and patterning by contact lithography, the diamond is etched in an inductively coupled oxygen plasma with zero platen power. The etch process effectively reveals the characteristic {111} diamond crystal planes, creating a precisely defined angled (54.7°) profile. SEM and AFM measurements of the fabricated gratings evidence the trapezoidal shape with a pitch of 3.82μm, depth of 170 nm and duty cycle of 35.5%. Optical characterization is performed in transmission using a 650nm laser source perpendicular to the sample. The recorded transmitted optical power as function of detector rotation angle shows a distribution of 21.1% in the 0th order and 23.6% in each +/-1st order (16.1% reflected, 16.6% in higher orders). To our knowledge, this is the first demonstration of diffraction gratings with trapezoidal profile in single crystal diamond. The fabrication process will enable beam splitter gratings of custom defined optical power distribution profiles, while antireflection coatings can increase the efficiency.
Twinning processes in Cu-Al-Ni martensite single crystals investigated by neutron single crystal diffraction method

International Nuclear Information System (INIS)

Molnar, P.; Sittner, P.; Novak, V.; Lukas, P.

2008-01-01

A neutron single crystal diffraction method for inspecting the quality of martensite single crystals is introduced. True interface-free martensite single crystals are indispensable for, e.g. measurement of elastic constants of phases by ultrasonic techniques. The neutron diffraction method was used to detect and distinguish the presence of individual lattice correspondence variants of the 2H orthorhombic martensite phase in Cu-Al-Ni as well as to follow the activity of twinning processes during the deformation test on the martensite variant single crystals. When preparing the martensite single variant prism-shaped crystals by compression deformation method, typically a small fraction of second unwanted martensitic variant (compound twin) remains in the prism samples. Due to the very low stress (∼1 MPa) for the compound twinning in many shape memory alloys, it is quite difficult not only to deplete the martensite prisms of all internal interfaces but mainly to keep them in the martensite single variant state for a long time needed for further investigations
Solving crystal structures from neutron diffraction data

International Nuclear Information System (INIS)

Wilson, C.C.

1987-07-01

In order to pursue crystal structure determination using neutron diffraction data, and given the wide experience available of solving structures using X-ray data, the codes used in X-ray structural analysis should be adapted to the different requirements of a neutron experiment. Modifications have been made to a direct methods program MITHRIL and to a Patterson methods program PATMET to incorporate into these the features of neutron rather than X-ray diffraction. While to date these modifications have been fairly straightforward and many sophistications remain to be exploited, results obtained from the neutron versions of both programs are promising. (author)
Diffractive-refractive optics: (+,-,-,+) X-ray crystal monochromator with harmonics separation.

Science.gov (United States)

Hrdý, Jaromír; Mikulík, Petr; Oberta, Peter

2011-03-01

A new kind of two channel-cut crystals X-ray monochromator in dispersive (+,-,-,+) position which spatially separates harmonics is proposed. The diffracting surfaces are oriented so that the diffraction is inclined. Owing to refraction the diffracted beam is sagittally deviated. The deviation depends on wavelength and is much higher for the first harmonics than for higher harmonics. This leads to spatial harmonics separation. The idea is supported by ray-tracing simulation.
Demonstrations with a Liquid Crystal Shutter

Science.gov (United States)

Kraftmakher, Yaakov

2012-01-01

The experiments presented show the response of a liquid crystal shutter to applied electric voltages and the delay of the operations. Both properties are important for liquid crystal displays of computers and television sets. Two characteristics of the shutter are determined: (i) the optical transmittance versus applied voltage of various…
Control of liquid crystal molecular orientation using ultrasound vibration

Energy Technology Data Exchange (ETDEWEB)

Taniguchi, Satoki [Faculty of Life and Medical Sciences, Doshisha University, 1-3 Tataramiyakodani, Kyotanabe, Kyoto 610-0321 (Japan); Wave Electronics Research Center, Doshisha University, 1-3 Tataramiyakodani, Kyotanabe, Kyoto 610-0321 (Japan); Koyama, Daisuke; Matsukawa, Mami [Wave Electronics Research Center, Doshisha University, 1-3 Tataramiyakodani, Kyotanabe, Kyoto 610-0321 (Japan); Faculty of Science and Engineering, Doshisha University, 1-3 Tataramiyakodani, Kyotanabe, Kyoto 610-0321 (Japan); Shimizu, Yuki; Emoto, Akira [Faculty of Science and Engineering, Doshisha University, 1-3 Tataramiyakodani, Kyotanabe, Kyoto 610-0321 (Japan); Nakamura, Kentaro [Precision and Intelligence Laboratory, Tokyo Institute of Technology, 4259-R2-26, Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan)

2016-03-07

We propose a technique to control the orientation of nematic liquid crystals using ultrasound and investigate the optical characteristics of the oriented samples. An ultrasonic liquid crystal cell with a thickness of 5–25 μm and two ultrasonic lead zirconate titanate transducers was fabricated. By exciting the ultrasonic transducers, the flexural vibration modes were generated on the cell. An acoustic radiation force to the liquid crystal layer was generated, changing the molecular orientation and thus the light transmission. By modulating the ultrasonic driving frequency and voltage, the spatial distribution of the molecular orientation of the liquid crystals could be controlled. The distribution of the transmitted light intensity depends on the thickness of the liquid crystal layer because the acoustic field in the liquid crystal layer is changed by the orientational film.
Direct observation of crystal texture by neutron diffraction topography

International Nuclear Information System (INIS)

Tomimitsu, Hiroshi

1982-02-01

This document reports the development and the applications of the neutron diffraction topography (NDT), which have been carried out at JAERI in these 10 years. This describes how the substructure of Cu-5%Ge single crystal of large-scale (3 cm in diameter and 10 cm in length) was revealed by the NDT-observation. It was discovered that the specimen crystal was made up from the layer-substructures parallel to (001) and to the [110] growth direction, and that each (001) layer-substructure mentioned above was further subdivided into the central thin sublayer parallel to (001) and thick plates of [100] and [010] directions, attached symmetrically to both sides of the central (001) sublayer with regular intervals. The model of the substructure described above was supported by the calculation of the diffraction intensities. The model of the layer-substructure described above, on the other hand, suggested a simple mechanism of crystal growth of the specimen. This document also reports the NDT-observation of the three-dimensional distribution of the lattice strains within a hot-pressed Ge single crystal, and the equal thickness fringes and the coherent boundaries of a twinned Si crystal. The powerfulness and the reliability of the NDT-technique were thus demonstrated. (author)
Alignment technology and applications of liquid crystal devices

CERN Document Server

Takatoh, Kohki; Hasegawa, Ray; Koden, Mitsushiro; Itoh, Nobuyuki; Hasegawa, Masaki

2005-01-01

Alignment phenomena are characteristic of liquid crystalline materials, and understanding them is critically important in understanding the essential features and behavior of liquid crystals and the performance of Liquid Crystal Devices (LCDs). Furthermore, in LCD production lines, the alignment process is of practical importance. Alignment Technologies and Applications of Liquid Crystal Devices demonstrates both the fundamental and practical aspects of alignment phenomena in liquid crystals. The physical basis of alignment phenomena is first introduced in order to aid the understanding of the various physical phenomena observed in the interface between liquid crystalline materials and alignment layer surfaces. Methods for the characterization of surfaces, which induce the alignment phenomena, and of the alignment layer itself are introduced. These methods are useful for the research of liquid crystalline materials and devices in academic research as well as in industry. In the practical sections, the alignme...
Crystallization of porcine pancreatic elastase and a preliminary neutron diffraction experiment

Energy Technology Data Exchange (ETDEWEB)

Kinoshita, Takayoshi [Department of Biological Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Tamada, Taro [Molecular Structural Biology Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai, Ibaraki 319-1195 (Japan); Imai, Keisuke [Lead Discovery Research Laboratories, Astellas Pharma Inc., 21 Miyukigaoka, Tsukuba-shi, Ibaraki 305-8585 (Japan); Kurihara, Kazuo; Ohhara, Takashi [Molecular Structural Biology Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai, Ibaraki 319-1195 (Japan); Tada, Toshiji [Department of Biological Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Kuroki, Ryota, E-mail: kuroki.ryota@jaea.go.jp [Molecular Structural Biology Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai, Ibaraki 319-1195 (Japan); Department of Biological Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan)

2007-04-01

To investigate the structural characteristics of a covalent inhibitor bound to porcine pancreatic elastase (PPE), including H atoms and hydration by water, a crystal of porcine pancreatic elastase with its inhibitor was grown to a size of 1.6 mm{sup 3} for neutron diffraction study. The crystal diffracted to 2.3 Å resolution with sufficient quality for further structure determination owing to the similar atomic scattering properties of deuterium and carbon. Porcine pancreatic elastase (PPE) resembles the attractive drug target leukocyte elastase, which has been implicated in a number of inflammatory disorders. In order to investigate the structural characteristics of a covalent inhibitor bound to PPE, including H atoms and the hydration by water, a single crystal of PPE for neutron diffraction study was grown in D{sub 2}O containing 0.2 M sodium sulfate (pD 5.0) using the sitting-drop vapour-diffusion method. The crystal was grown to a size of 1.6 mm{sup 3} by repeated macroseeding. Neutron diffraction data were collected at room temperature using a BIX-3 diffractometer at the JRR-3 research reactor of the Japan Atomic Energy Agency (JAEA). The data set was integrated and scaled to 2.3 Å resolution in space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 51.2, b = 57.8, c = 75.6 Å.
Long wave-length x-ray diffraction crystal and method of manufacturing same

International Nuclear Information System (INIS)

Zingaro, W.P.; Sicignano, A.

1980-01-01

An x-ray diffraction crystal of the Langemuir-Blodgett type capable of detecting radiation having a wavelength greater than 50 Arystroms and a method of making such a crystal are described. The crystal consists of a pair of alternate monolayers, one a heavy metal soap, and one a light metal soap. Selecting cation pairs with a significant difference in atomic number and dispersing power, such as Pb and Be, Mg, or Ca, increases the effective interplanar distance since the Pb planes cause the predominant x-ray diffraction. (LL)
Application of liquid crystals in thermal nondestructive evaluation

International Nuclear Information System (INIS)

Panakal, J.P.; Mukherjee, S.; Ghosh, J.K.

1983-01-01

In recent years, thermal nondestructive evaluation using Cholestric liquid crystals have found wide applications in industry. Thermography using Cholesteric liquid crystals can be used for detection of nonbonds in metallic composites, hot spots in electronic circuits and preliminary examination of welded pressure vessels. This paper presents the results of experiments on thermography of components using encapsulated liquid crystals. (author)
Thermalization calorimetry: A simple method for investigating glass transition and crystallization of supercooled liquids

Directory of Open Access Journals (Sweden)

Bo Jakobsen

2016-05-01

Full Text Available We present a simple method for fast and cheap thermal analysis on supercooled glass-forming liquids. This “Thermalization Calorimetry” technique is based on monitoring the temperature and its rate of change during heating or cooling of a sample for which the thermal power input comes from heat conduction through an insulating material, i.e., is proportional to the temperature difference between sample and surroundings. The monitored signal reflects the sample’s specific heat and is sensitive to exo- and endothermic processes. The technique is useful for studying supercooled liquids and their crystallization, e.g., for locating the glass transition and melting point(s, as well as for investigating the stability against crystallization and estimating the relative change in specific heat between the solid and liquid phases at the glass transition.
Crystallization and preliminary X-ray diffraction analysis of mevalonate kinase from Methanosarcina mazei

International Nuclear Information System (INIS)

Zhuang, Ningning; Seo, Kyung Hye; Chen, Cong; Zhou, Jia; Kim, Seon Won; Lee, Kon Ho

2012-01-01

Recombinant mevalonate kinase from M. mazei has been crystallized. Diffraction data were collected to 2.08 Å resolution. Mevalonate kinase (MVK), which plays an important role in catalysing the biosynthesis of isoprenoid compounds derived from the mevalonate pathway, transforms mevalonate to 5-phosphomevalonate using ATP as a cofactor. Mevalonate kinase from Methanosarcina mazei (MmMVK) was expressed in Escherichia coli, purified and crystallized for structural analysis. Diffraction-quality crystals of MmMVK were obtained by the vapour-diffusion method using 0.32 M MgCl 2 , 0.08 M bis-tris pH 5.5, 16%(w/v) PEG 3350. The crystals belonged to space group P2 1 2 1 2, with unit-cell parameters a = 97.11, b = 135.92, c = 46.03 Å. Diffraction data were collected to 2.08 Å resolution
Quantum Dot/Liquid Crystal Nanocomposites in Photonic Devices

Directory of Open Access Journals (Sweden)

Andrea L. Rodarte

2015-07-01

Full Text Available Quantum dot/liquid crystal nano-composites are promising new materials for a variety of applications in energy harvesting, displays and photonics including the liquid crystal laser. To realize many applications, however, we need to control and stabilize nano-particle dispersion in different liquid crystal host phases and understand how the particles behave in an anisotropic fluid. An ideal system will allow for the controlled assembly of either well-defined nano-particle clusters or a uniform particle distribution. In this paper, we investigate mesogen-functionalized quantum dots for dispersion in cholesteric liquid crystal. These nanoparticles are known to assemble into dense stable packings in the nematic phase, and such structures, when localized in the liquid crystal defects, can potentially enhance the coupling between particles and a cholesteric cavity. Controlling the dispersion and assembly of quantum dots using mesogenic surface ligands, we demonstrate how resonant fluid photonic cavities can result from the co-assembly of luminescent nanoparticles in the presence of cholesteric liquid crystalline ordering.
Time-resolved crystallization of deeply cooled liquid hydrogen isotopes

Energy Technology Data Exchange (ETDEWEB)

Kuehnel, Matthias

2014-02-15

This thesis serves two main purposes: 1. The introduction of a novel experimental method to investigate phase change dynamics of supercooled liquids 2. First-time measurements for the crystallization behaviour for hydrogen isotopes under various conditions (1) The new method is established by the synergy of a liquid microjet of ∼ 5 μm diameter and a scattering technique with high spatial resolution, here linear Raman spectroscopy. Due to the high directional stability and the known velocity of the liquid filament, its traveling axis corresponds to a time axis static in space. Utilizing evaporative cooling in a vacuum environment, the propagating liquid cools down rapidly and eventually experiences a phase transition to the crystalline state. This temporal evolution is probed along the filament axis, ultimately resulting in a time resolution of 10 ns. The feasibility of this approach is proven successfully within the following experiments. (2) A main object of study are para-hydrogen liquid filaments. Raman spectra reveal a temperature gradient of the liquid across the filament. This behaviour can quantitatively be reconstructed by numerical simulations using a layered model and is rooted in the effectiveness of evaporative cooling on the surface and a finite thermal conductivity. The deepest supercoolings achieved are ∼ 30% below the melting point, at which the filament starts to solidify from the surface towards the core. With a crystal growth velocity extracted from the data the appropriate growth mechanism is identified. The crystal structure that initially forms is metastable and probably the result of Ostwald's rule of stages. Indications for a transition within the solid towards the stable equilibrium phase support this interpretation. The analog isotope ortho-deuterium is evidenced to behave qualitatively similar with quantitative differences being mass related. In further measurements, isotopic mixtures of para-hydrogen and ortho-deuterium are
Time-resolved crystallization of deeply cooled liquid hydrogen isotopes

International Nuclear Information System (INIS)

Kuehnel, Matthias

2014-02-01

This thesis serves two main purposes: 1. The introduction of a novel experimental method to investigate phase change dynamics of supercooled liquids 2. First-time measurements for the crystallization behaviour for hydrogen isotopes under various conditions (1) The new method is established by the synergy of a liquid microjet of ∼ 5 μm diameter and a scattering technique with high spatial resolution, here linear Raman spectroscopy. Due to the high directional stability and the known velocity of the liquid filament, its traveling axis corresponds to a time axis static in space. Utilizing evaporative cooling in a vacuum environment, the propagating liquid cools down rapidly and eventually experiences a phase transition to the crystalline state. This temporal evolution is probed along the filament axis, ultimately resulting in a time resolution of 10 ns. The feasibility of this approach is proven successfully within the following experiments. (2) A main object of study are para-hydrogen liquid filaments. Raman spectra reveal a temperature gradient of the liquid across the filament. This behaviour can quantitatively be reconstructed by numerical simulations using a layered model and is rooted in the effectiveness of evaporative cooling on the surface and a finite thermal conductivity. The deepest supercoolings achieved are ∼ 30% below the melting point, at which the filament starts to solidify from the surface towards the core. With a crystal growth velocity extracted from the data the appropriate growth mechanism is identified. The crystal structure that initially forms is metastable and probably the result of Ostwald's rule of stages. Indications for a transition within the solid towards the stable equilibrium phase support this interpretation. The analog isotope ortho-deuterium is evidenced to behave qualitatively similar with quantitative differences being mass related. In further measurements, isotopic mixtures of para-hydrogen and ortho-deuterium are
Time-resolved crystallization of deeply cooled liquid hydrogen isotopes

Energy Technology Data Exchange (ETDEWEB)

Kuehnel, Matthias

2014-02-15

This thesis serves two main purposes: 1. The introduction of a novel experimental method to investigate phase change dynamics of supercooled liquids 2. First-time measurements for the crystallization behaviour for hydrogen isotopes under various conditions (1) The new method is established by the synergy of a liquid microjet of ∼ 5 μm diameter and a scattering technique with high spatial resolution, here linear Raman spectroscopy. Due to the high directional stability and the known velocity of the liquid filament, its traveling axis corresponds to a time axis static in space. Utilizing evaporative cooling in a vacuum environment, the propagating liquid cools down rapidly and eventually experiences a phase transition to the crystalline state. This temporal evolution is probed along the filament axis, ultimately resulting in a time resolution of 10 ns. The feasibility of this approach is proven successfully within the following experiments. (2) A main object of study are para-hydrogen liquid filaments. Raman spectra reveal a temperature gradient of the liquid across the filament. This behaviour can quantitatively be reconstructed by numerical simulations using a layered model and is rooted in the effectiveness of evaporative cooling on the surface and a finite thermal conductivity. The deepest supercoolings achieved are ∼ 30% below the melting point, at which the filament starts to solidify from the surface towards the core. With a crystal growth velocity extracted from the data the appropriate growth mechanism is identified. The crystal structure that initially forms is metastable and probably the result of Ostwald's rule of stages. Indications for a transition within the solid towards the stable equilibrium phase support this interpretation. The analog isotope ortho-deuterium is evidenced to behave qualitatively similar with quantitative differences being mass related. In further measurements, isotopic mixtures of para-hydrogen and ortho-deuterium are
X-ray diffraction studies of NbTe 2 single crystal

Indian Academy of Sciences (India)

The composition of the grown crystals was confirmed on the basis of energy dispersive analysis by X-ray (EDAX) and remaining structural characterization was also accomplished by X-ray diffraction (XRD) studies. Lattice parameters, volume and X-ray density have been carried out for the grown crystals. The particle size ...
Modified dynamical equation for dye doped nematic liquid crystals

Energy Technology Data Exchange (ETDEWEB)

Manohar, Rajiv, E-mail: rajlu1@rediffmail.co [Liquid Crystal Research Lab, Physics Department, University of Lucknow, Lucknow 226007 (India); Misra, Abhishek Kumar; Srivastava, Abhishek Kumar [Liquid Crystal Research Lab, Physics Department, University of Lucknow, Lucknow 226007 (India)

2010-04-15

Dye doped liquid crystals show changed dielectric properties in comparison to pure liquid crystals. These changes are strongly dependent on the concentration of dye. In the present work we have measured dielectric properties of standard nematic liquid crystals E-24 and its two guest host mixtures of different concentrations with Anthraquinone dye D5. The experimental results are fitted using linear response and in the light of this we have proposed some modifications in the dynamical equation for the nematic liquid crystals by introducing two new variables as dye concentration coefficients. The limitations of the proposed equation in high temperature range have also been discussed. With the help of the proposed dynamical equation for the guest-host liquid crystals (GHLCs) it is possible to predict the various parameters like rotational viscosity, dielectric anisotropy and relaxation time for GHLCs at other concentrations of dye in liquid crystals theoretically.
Nanoscience with liquid crystals from self-organized nanostructures to applications

CERN Document Server

Li, Quan

2014-01-01

This book focuses on the exciting topic of nanoscience with liquid crystals: from self-organized nanostructures to applications. The elegant self-organized liquid crystalline nanostructures, the synergetic characteristics of liquid crystals and nanoparticles, liquid crystalline nanomaterials, synthesis of nanomaterials using liquid crystals as templates, nanoconfinement and nanoparticles of liquid crystals are covered and discussed, and the prospect of fabricating functional materials is highlighted. Contributions, collecting the scattered literature of the field from leading and active player

Crystallization and preliminary X-ray diffraction studies of ferredoxin reductase from Leptospira interrogans

International Nuclear Information System (INIS)

Nascimento, Alessandro S.; Ferrarezi, Thiago; Catalano-Dupuy, Daniela L.; Ceccarelli, Eduardo A.; Polikarpov, Igor

2006-01-01

Crystals adequate for X-ray diffraction analysis have been prepared from L. interrogans ferredoxin-NADP + reductase. Ferredoxin-NADP + reductase (FNR) is an FAD-containing enzyme that catalyzes electron transfer between NADP(H) and ferredoxin. Here, results are reported of the recombinant expression, purification and crystallization of FNR from Leptospira interrogans, a parasitic bacterium of animals and humans. The L. interrogans FNR crystals belong to a primitive monoclinic space group and diffract to 2.4 Å resolution at a synchrotron source
Crystallization and preliminary X-ray diffraction studies of ferredoxin reductase from Leptospira interrogans

Energy Technology Data Exchange (ETDEWEB)

Nascimento, Alessandro S.; Ferrarezi, Thiago [Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador Saocarlense 400, São Carlos, SP, 13560-970 (Brazil); Catalano-Dupuy, Daniela L.; Ceccarelli, Eduardo A. [Facultad de Ciencias Bioquímicas y Farmacéuticas, Molecular Biology Division, Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario (Argentina); Polikarpov, Igor, E-mail: ipolikarpov@if.sc.usp.br [Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador Saocarlense 400, São Carlos, SP, 13560-970 (Brazil)

2006-07-01

Crystals adequate for X-ray diffraction analysis have been prepared from L. interrogans ferredoxin-NADP{sup +} reductase. Ferredoxin-NADP{sup +} reductase (FNR) is an FAD-containing enzyme that catalyzes electron transfer between NADP(H) and ferredoxin. Here, results are reported of the recombinant expression, purification and crystallization of FNR from Leptospira interrogans, a parasitic bacterium of animals and humans. The L. interrogans FNR crystals belong to a primitive monoclinic space group and diffract to 2.4 Å resolution at a synchrotron source.
Liquid crystal dimers

CERN Document Server

Kumar Pal, Santanu

2017-01-01

This book covers in-depth discussion of design principles, synthesis and thermal behavior of all types of liquid crystal (LC) dimers. The text presents recent advances in the field of LC dimers consisting of different mesogenic units such as calamitic, discotic and bent-core molecules. It starts with a chapter on the introduction of liquid crystal dimers, including their odd-even behavior, basic classification of dimers and common mesophases in dimers. The text shows how the molecular architectures are being used to develop new materials to study a range of interesting phenomena such as the biaxial nematic phase containing rod-like and disc-like mesogenic units. Finally, the text presents perspectives related to technological relevance of these dimers such as dopants in LC display mixtures exhibiting faster relaxation time, strong flexoelectric coupling and others to effect control over the properties of these materials.
Liquid crystals: high technology materials for potential applications

International Nuclear Information System (INIS)

Saeed, M.A.; Badaruddin; Rizvi, T.Z.

1993-01-01

Liquid crystals have very rapidly emerged as a basis of many high technology fields within the last few decades. These materials because of their intriguing physical properties are regarded as the fourth state of matter. At present the applications of liquid crystals are established in digital display devices, electro-optical switches, optical computing, acousto-optics, thermo-indicators, laser thermo-recording, photo-chemical image recording and optical communication networks. More recently due to the concept of molecularly based electronics (MBE): the logical extreme for miniaturization of electronic device, liquid crystals are foreseen to play a vital role in the future optics based technologies. This paper gives a brief introduction to liquid crystals, the types of meso phases found in these materials together with their applications in research and industry. Some technical details of the construction liquid crystal cells for some typical applications in digital displays and other electro optical devices have also been discussed with special emphasis on relevant physical processes occurring at molecular level. (author)
Insertion of liquid crystal molecules into hydrocarbon monolayers

Energy Technology Data Exchange (ETDEWEB)

Popov, Piotr, E-mail: ppopov@kent.edu; Mann, Elizabeth K. [Department of Physics, Kent State University, Kent, Ohio 44242 (United States); Lacks, Daniel J. [Department of Chemical Engineering, Case Western Reserve University, Cleveland, Ohio 44106 (United States); Jákli, Antal [Liquid Crystal Institute, Kent State University, Kent, Ohio 44242-0001 (United States)

2014-08-07

Atomistic molecular dynamics simulations were carried out to investigate the molecular mechanisms of vertical surface alignment of liquid crystals. We study the insertion of nCB (4-Cyano-4{sup ′}-n-biphenyl) molecules with n = 0,…,6 into a bent-core liquid crystal monolayer that was recently found to provide good vertical alignment for liquid crystals. The results suggest a complex-free energy landscape for the liquid crystal within the layer. The preferred insertion direction of the nCB molecules (core or tail first) varies with n, which can be explained by entropic considerations. The role of the dipole moments was found to be negligible. As vertical alignment is the leading form of present day liquid crystal displays (LCD), these results will help guide improvement of the LCD technology, as well as lend insight into the more general problem of insertion of biological and other molecules into lipid and surfactant layers.
Liquid crystals with novel terminal chains as ferroelectric liquid crystal hosts

International Nuclear Information System (INIS)

Cosquer, G.Y.

2000-02-01

Changes to the molecular structure of liquid crystals can have a significant effect upon their mesomorphism and ferroelectric properties. Most of the research in liquid crystal for display applications concentrates on the design and synthesis of novel mesogenic cores to which straight terminal alkyl or alkoxy chains are attached. However, little is known about the effects upon the mesomorphism and ferroelectric properties of varying the terminal chains. The compounds prepared in this work have a common core - a 2,3-difluoroterphenyl unit with a nine-atom alkyl (nonyl) or alkoxy (octyloxy) chain at the 4-position, but with an unusual chain at the 4''-position. In some cases the terminal chain contains hetero atoms such as silicon, oxygen, chlorine and bromine or has a bulky end group. In total 46 final materials were synthesised in an attempt to understand the effect of an unusual terminal chains on mesomorphism and for some of these compounds the effect upon the switching times when added to a standard ferroelectric mixture were investigated. It was found that most compounds containing a bulky end group only displayed a smectic C phase, compounds with a halogen substituent as an end unit displayed a smectic A phase and that increasing the chain flexibility by introducing an oxygen atom in the chain reduces the melting and clearing points. The electro-optical measurements carried out on ferroelectric mixtures containing a bulky end group compound showed that shorter switching times were produced than for the ferroelectric mixture containing a straight chain compound. It is suggested that a bulky end group diminishes te extent of interlayer mixing in the chiral smectic C phase and therefore the molecules move more easily with ferroelectric switching. (author)
Multiple x-ray diffraction simulation and applications

International Nuclear Information System (INIS)

Costa, C.A.B.S. da.

1989-09-01

A computer program (MULTX) was implemented for simulation X-ray multiple diffraction diagrams in Renninger geometries. The program uses the X-ray multiple diffraction theory for imperfect crystals. The iterative calculation of the intensities is based on the Taylor series general term, and the primary beam power expansion is given as function of the beam x penetration in the crystal surface. This development allows to consider the simultaneous interaction of the beams involved in the multiple diffraction phenomenon. The simulated diagrams are calculated point-to-point and the tests for the Si and GaAs presented good reproduction of the experimental diagrams for different primary reflections. (L.C.J.A.)
In situ high-pressure measurement of crystal solubility by using neutron diffraction

Science.gov (United States)

Chen, Ji; Hu, Qiwei; Fang, Leiming; He, Duanwei; Chen, Xiping; Xie, Lei; Chen, Bo; Li, Xin; Ni, Xiaolin; Fan, Cong; Liang, Akun

2018-05-01

Crystal solubility is one of the most important thermo-physical properties and plays a key role in industrial applications, fundamental science, and geoscientific research. However, high-pressure in situ measurements of crystal solubility remain very challenging. Here, we present a method involving high-pressure neutron diffraction for making high-precision in situ measurements of crystal solubility as a function of pressure over a wide range of pressures. For these experiments, we designed a piston-cylinder cell with a large chamber volume for high-pressure neutron diffraction. The solution pressures are continuously monitored in situ based on the equation of state of the sample crystal. The solubility at a high pressure can be obtained by applying a Rietveld quantitative multiphase analysis. To evaluate the proposed method, we measured the high-pressure solubility of NaCl in water up to 610 MPa. At a low pressure, the results are consistent with the previous results measured ex situ. At a higher pressure, more reliable data could be provided by using an in situ high-pressure neutron diffraction method.
Electrically tunable liquid crystal photonic bandgap fiber laser

DEFF Research Database (Denmark)

Olausson, Christina Bjarnal Thulin; Scolari, Lara; Wei, Lei

2010-01-01

We demonstrate electrical tunability of a fiber laser by using a liquid crystal photonic bandgap fiber. Tuning of the laser is achieved by combining the wavelength filtering effect of a liquid crystal photonic bandgap fiber device with an ytterbium-doped photonic crystal fiber. We fabricate an al...
Liquid crystal parameter analysis for tunable photonic bandgap fiber devices

DEFF Research Database (Denmark)

Weirich, Johannes; Lægsgaard, Jesper; Wei, Lei

2010-01-01

We investigate the tunability of splay-aligned liquid crystals for the use in solid core photonic crystal fibers. Finite element simulations are used to obtain the alignment of the liquid crystals subject to an external electric field. By means of the liquid crystal director field the optical...
Slit and phase grating diffraction with a double crystal diffractometer

International Nuclear Information System (INIS)

Treimer, Wolfgang; Hilger, Andre; Strobl, Markus

2006-01-01

The lateral coherence properties of a neutron beam (λ=0.5248nm) in a double crystal diffractometer (DCD) were studied by means of single slit diffraction and by diffraction by different perfect Silicon phase gratings. Perfect agreements were found for the lateral coherence length measured with the slit and for the one determined by Silicon phase gratings, however, some peculiarities are still present
A diamond-anvil high-pressure cell for X-ray diffraction on a single crystal

International Nuclear Information System (INIS)

Malinowski, M.

1987-01-01

A new diamond-anvil high-pressure cell is described which can be used in single-crystal X-ray diffraction instruments to collect X-ray intensity data from single-crystal samples up to hydrostatic pressures of about 10 GPa. A unique design allows two types of diffraction geometry to be applied in single-crystal high-pressure diffraction experiments. More than 85% of the Ewald sphere is accessible, and a continuous range of 2θ values is available from 0 up to about 160 0 . Pressure may be calibrated by the ruby fluorescence technique or by the use of an internal X-ray-standard single crystal. The design of our diamond-anvil cell would allow, with little or no modification, operation at high and low temperatures, optical studies and powder diffractometer work. (orig.)
Purification, crystallization and preliminary X-ray diffraction experiment of nattokinase from Bacillus subtilis natto

International Nuclear Information System (INIS)

Yanagisawa, Yasuhide; Chatake, Toshiyuki; Chiba-Kamoshida, Kaori; Naito, Sawa; Ohsugi, Tadanori; Sumi, Hiroyuki; Yasuda, Ichiro; Morimoto, Yukio

2010-01-01

Nattokinase, a protein found in high levels in the traditional Japanese food natto, has been reported to have high thrombolytic activity. In the present study, the crystallization of native nattokinase and the collection of X-ray diffraction date from a nattokinase crystal to a resolution of 1.74 Å are reported. Nattokinase is a single polypeptide chain composed of 275 amino acids (molecular weight 27 724) which displays strong fibrinolytic activity. Moreover, it can activate other fibrinolytic enzymes such as pro-urokinase and tissue plasminogen activator. In the present study, native nattokinase from Bacillus subtilis natto was purified using gel-filtration chromatography and crystallized to give needle-like crystals which could be used for X-ray diffraction experiments. The crystals belonged to space group C2, with unit-cell parameters a = 74.3, b = 49.9, c = 56.3 Å, β = 95.2°. Diffraction images were processed to a resolution of 1.74 Å with an R merge of 5.2% (15.3% in the highest resolution shell) and a completeness of 69.8% (30.0% in the highest resolution shell). This study reports the first X-ray diffraction analysis of nattokinase
Purification, crystallization and preliminary X-ray diffraction experiment of nattokinase from Bacillus subtilis natto

Energy Technology Data Exchange (ETDEWEB)

Yanagisawa, Yasuhide [Faculty of Pharmaceutical Sciences, Chiba Institute of Science, 15-8 Shiomi-cho, Choshi, Chiba 288-0025 (Japan); Chatake, Toshiyuki [Research Reactor Institute, Kyoto University, Asashironishi 2, Kumatori, Sennan, Osaka 590-0494 (Japan); Chiba-Kamoshida, Kaori [National Institute of Advanced Industrial Science and Technology (AIST), Umezono 1-1-1, Tsukuba, Ibaraki 305-8568 (Japan); Naito, Sawa; Ohsugi, Tadanori; Sumi, Hiroyuki [Kurashiki University of Science and Arts, Nishinoura 2640, Tsurajima-cho, Kurashiki, Okayama 712-8505 (Japan); Yasuda, Ichiro [Faculty of Pharmaceutical Sciences, Chiba Institute of Science, 15-8 Shiomi-cho, Choshi, Chiba 288-0025 (Japan); Morimoto, Yukio [Research Reactor Institute, Kyoto University, Asashironishi 2, Kumatori, Sennan, Osaka 590-0494 (Japan); Faculty of Pharmaceutical Sciences, Chiba Institute of Science, 15-8 Shiomi-cho, Choshi, Chiba 288-0025 (Japan)

2010-12-01

Nattokinase, a protein found in high levels in the traditional Japanese food natto, has been reported to have high thrombolytic activity. In the present study, the crystallization of native nattokinase and the collection of X-ray diffraction date from a nattokinase crystal to a resolution of 1.74 Å are reported. Nattokinase is a single polypeptide chain composed of 275 amino acids (molecular weight 27 724) which displays strong fibrinolytic activity. Moreover, it can activate other fibrinolytic enzymes such as pro-urokinase and tissue plasminogen activator. In the present study, native nattokinase from Bacillus subtilis natto was purified using gel-filtration chromatography and crystallized to give needle-like crystals which could be used for X-ray diffraction experiments. The crystals belonged to space group C2, with unit-cell parameters a = 74.3, b = 49.9, c = 56.3 Å, β = 95.2°. Diffraction images were processed to a resolution of 1.74 Å with an R{sub merge} of 5.2% (15.3% in the highest resolution shell) and a completeness of 69.8% (30.0% in the highest resolution shell). This study reports the first X-ray diffraction analysis of nattokinase.
Large three-dimensional photonic crystals based on monocrystalline liquid crystal blue phases.

Science.gov (United States)

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

2017-09-28

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

Science.gov (United States)

1978-09-01

polarizers (e.g., where p is the distance of alignment or pitch, X is the Nicol, Rochon, and Wollaston prisms ) are based upon peak wavelength of scattered...RANGE OF so 45" 45 - EVENT SEVENT T(°C) TEMPERATUJRE TC)4"TEMPERATURE 40RANGE OF T(°) 0-RANGE OF 40LIQUID ’ ൫" CRYSTAL S 36 3S. 30 0 IS 90 180 - I...Temperatures TI > T2 > - > TS defects was possible using the liquid crystal. are the Average TemperatursI Thes Resptivegi. Kapfer , Burns, Salvo, and Doyle
Liquid crystals in micron-scale droplets, shells and fibers

Science.gov (United States)

Urbanski, Martin; Reyes, Catherine G.; Noh, JungHyun; Sharma, Anshul; Geng, Yong; Subba Rao Jampani, Venkata; Lagerwall, Jan P. F.

2017-04-01

The extraordinary responsiveness and large diversity of self-assembled structures of liquid crystals are well documented and they have been extensively used in devices like displays. For long, this application route strongly influenced academic research, which frequently focused on the performance of liquid crystals in display-like geometries, typically between flat, rigid substrates of glass or similar solids. Today a new trend is clearly visible, where liquid crystals confined within curved, often soft and flexible, interfaces are in focus. Innovation in microfluidic technology has opened for high-throughput production of liquid crystal droplets or shells with exquisite monodispersity, and modern characterization methods allow detailed analysis of complex director arrangements. The introduction of electrospinning in liquid crystal research has enabled encapsulation in optically transparent polymeric cylinders with very small radius, allowing studies of confinement effects that were not easily accessible before. It also opened the prospect of functionalizing textile fibers with liquid crystals in the core, triggering activities that target wearable devices with true textile form factor for seamless integration in clothing. Together, these developments have brought issues center stage that might previously have been considered esoteric, like the interaction of topological defects on spherical surfaces, saddle-splay curvature-induced spontaneous chiral symmetry breaking, or the non-trivial shape changes of curved liquid crystal elastomers with non-uniform director fields that undergo a phase transition to an isotropic state. The new research thrusts are motivated equally by the intriguing soft matter physics showcased by liquid crystals in these unconventional geometries, and by the many novel application opportunities that arise when we can reproducibly manufacture these systems on a commercial scale. This review attempts to summarize the current understanding of
Liquid crystals in micron-scale droplets, shells and fibers

International Nuclear Information System (INIS)

Urbanski, Martin; Reyes, Catherine G; Noh, JungHyun; Sharma, Anshul; Geng, Yong; Subba Rao Jampani, Venkata; Lagerwall, Jan P F

2017-01-01

The extraordinary responsiveness and large diversity of self-assembled structures of liquid crystals are well documented and they have been extensively used in devices like displays. For long, this application route strongly influenced academic research, which frequently focused on the performance of liquid crystals in display-like geometries, typically between flat, rigid substrates of glass or similar solids. Today a new trend is clearly visible, where liquid crystals confined within curved, often soft and flexible, interfaces are in focus. Innovation in microfluidic technology has opened for high-throughput production of liquid crystal droplets or shells with exquisite monodispersity, and modern characterization methods allow detailed analysis of complex director arrangements. The introduction of electrospinning in liquid crystal research has enabled encapsulation in optically transparent polymeric cylinders with very small radius, allowing studies of confinement effects that were not easily accessible before. It also opened the prospect of functionalizing textile fibers with liquid crystals in the core, triggering activities that target wearable devices with true textile form factor for seamless integration in clothing. Together, these developments have brought issues center stage that might previously have been considered esoteric, like the interaction of topological defects on spherical surfaces, saddle-splay curvature-induced spontaneous chiral symmetry breaking, or the non-trivial shape changes of curved liquid crystal elastomers with non-uniform director fields that undergo a phase transition to an isotropic state. The new research thrusts are motivated equally by the intriguing soft matter physics showcased by liquid crystals in these unconventional geometries, and by the many novel application opportunities that arise when we can reproducibly manufacture these systems on a commercial scale. This review attempts to summarize the current understanding of
High heat load performance of an inclined crystal monochromator with liquid gallium cooling on the CHESS-ANL undulator

International Nuclear Information System (INIS)

Macrander, A.T.; Lee, W.K.; Smither, R.K.; Mills, D.M.

1992-01-01

Recent results for the performance of a novel double crystal monochromator subjected to high heat loads on an APS prototype undulator at the Cornell High Energy Synchrotron Source (CHESS) are presented. The monochromator was designed to achieve symmetric diffraction from asymmetric planes to spread out the beam footprint thereby lowering the incident power density. Both crystals had (111) oriented surfaces and were arranged such that the beam was diffracted from the (11 bar 1) planes at 5 KeV. Rocking curves with minimal distortion were obtained at a ring electron current of 100 mA. This corresponded to 380 Watts total power and an average power density of 40 Watts/mm 2 normal to the incident beam. These results are compared to data obtained from the same crystals in the standard geometry (diffracting planes parallel to surface). The footprint area in the inclined case was three times that of the standard case. We also obtained rocking curve data for the (333) reflection at 15 KeV for both standard and inclined cases, and these data also showed a minimal distortion only for the inclined case. In addition, thermal data were obtained via infrared pyrometry. Liquid gallium flow rates of up to 2 gallons per minute were investigated. The diffraction data revealed a dramatically improved performance for the inclined crystal case
Tunable photoluminescence of porous silicon by liquid crystal infiltration

International Nuclear Information System (INIS)

Ma Qinglan; Xiong Rui; Huang Yuanming

2011-01-01

The photoluminescence (PL) of porous silicon films has been investigated as a function of the amount of liquid crystal molecules that are infiltrated into the constricted geometry of the porous silicon films. A typical nematic liquid crystal 4-pentyl-4'-cyanobiphenyl was employed in our experiment as the filler to modify the PL of porous silicon. It is found that the originally red PL of porous silicon films can be tuned to blue by simply adjusting the amount of liquid crystal molecules in the microchannels of the porous films. The chromaticity coordinates are calculated for the recorded PL spectra. The mechanism of the tunable PL is discussed. Our results have demonstrated that the luminescent properties of porous silicon films can be efficiently tuned by liquid crystal infiltration. - Highlights: → Liquid crystal infiltration can tune the photoluminescence of porous silicon. → Red emission of porous silicon can be switched to blue by the infiltration. → Chromaticity coordinates are calculated for the tuned emissions. → White emission is realized for porous silicon by liquid crystal infiltration.

Polymerization speed and diffractive experiments in polymer network LC test cells

Science.gov (United States)

Braun, Larissa; Gong, Zhen; Habibpourmoghadam, Atefeh; Schafforz, Samuel L.; Wolfram, Lukas; Lorenz, Alexander

2018-02-01

Polymer-network liquid crystals (LCs), where the response properties of a LC can be enhanced by the presence of a porous polymer network, are investigated. In the reported experiments, liquid crystals were doped with a small amount (situ generated polymer network, the electro-optic response properties of photo cured samples were enhanced. For example, their continuous phase modulation properties led to more localized responses in samples with interdigitated electrodes, which caused suppression of selected diffraction orders in the diffraction patterns recorded in polymer network LC samples. Moreover, capacitance changes were investigated during photopolymerization of a blue phase LC.
Liquid Crystals in Tribology

Directory of Open Access Journals (Sweden)

María-Dolores Bermúdez

2009-09-01

Full Text Available Two decades ago, the literature dealing with the possible applications of low molar mass liquid crystals, also called monomer liquid crystals (MLCs, only included about 50 references. Today, thousands of papers, conference reports, books or book chapters and patents refer to the study and applications of MLCs as lubricants and lubricant additives and efforts are made to develop new commercial applications. The development of more efficient lubricants is of paramount technological and economic relevance as it is estimated that half the energy consumption is dissipated as friction. MLCs have shown their ability to form ordered boundary layers with good load-carrying capacity and to lower the friction coefficients, wear rates and contact temperature of sliding surfaces, thus contributing to increase the components service life and to save energy. This review includes the use of MLCs in lubrication, and dispersions of MLCs in conventional polymers (PDMLCs. Finally, new lubricating system composed of MLC blends with surfactants, ionic liquids or nanophases are considered.
Liquid crystals in tribology.

Science.gov (United States)

Carrión, Francisco-José; Martínez-Nicolás, Ginés; Iglesias, Patricia; Sanes, José; Bermúdez, María-Dolores

2009-09-18

Two decades ago, the literature dealing with the possible applications of low molar mass liquid crystals, also called monomer liquid crystals (MLCs), only included about 50 references. Today, thousands of papers, conference reports, books or book chapters and patents refer to the study and applications of MLCs as lubricants and lubricant additives and efforts are made to develop new commercial applications. The development of more efficient lubricants is of paramount technological and economic relevance as it is estimated that half the energy consumption is dissipated as friction. MLCs have shown their ability to form ordered boundary layers with good load-carrying capacity and to lower the friction coefficients, wear rates and contact temperature of sliding surfaces, thus contributing to increase the components service life and to save energy. This review includes the use of MLCs in lubrication, and dispersions of MLCs in conventional polymers (PDMLCs). Finally, new lubricating system composed of MLC blends with surfactants, ionic liquids or nanophases are considered.
Tunable bandpass filter based on photonic crystal fiber filled with multiple liquid crystals

DEFF Research Database (Denmark)

Scolari, Lara; Tartarini, G.; Borelli, E.

2007-01-01

A tunable bandpass filter based on a photonic crystal fiber filled with two different liquid crystals is demonstrated. 130 nm bandwidth tunability is achieved by tuning the temperature from 30degC to 90degC.......A tunable bandpass filter based on a photonic crystal fiber filled with two different liquid crystals is demonstrated. 130 nm bandwidth tunability is achieved by tuning the temperature from 30degC to 90degC....
Simulation of liquid crystals. Disclinations and surface modification

International Nuclear Information System (INIS)

Downton, M.

2001-01-01

In this thesis we investigate the behaviour of molecular models liquid crystals in several different situations. Basic introductory material on liquid crystals and computer simulations is discussed in the first two chapters, we then discuss the research. The third chapter investigates the interaction between a liquid crystal and a modified surface. A confined system of hard spherocylinders in a slab geometry is examined. The surface consists of planar hard walls with elongated molecules grafted perpendicularly onto them. The concentration of grafted molecules is varied to give different surfaces. Several different behaviours are found including planar, homeotropic and tilted anchorings of the liquid crystal. Molecular dynamics simulations of a nematic liquid crystal in slab geometry with twisted boundary conditions are performed. By arranging the initial configuration suitably it is possible to create a simulation cell with two regions of opposite twist separated by a strength half disclination line. The properties of the line are examined both with and without an applied external field. Finally, we again examine the system of grafted molecules on a flat substrate using an atomistic model of both the liquid crystal and the surface molecules. Again the effect of varying the density of grafted molecules is found to change the anchoring characteristics of the surface; both homeotropic and planar anchorings are observed. (author)
Accurate Charge Densities from Powder Diffraction

DEFF Research Database (Denmark)

Bindzus, Niels; Wahlberg, Nanna; Becker, Jacob

Synchrotron powder X-ray diffraction has in recent years advanced to a level, where it has become realistic to probe extremely subtle electronic features. Compared to single-crystal diffraction, it may be superior for simple, high-symmetry crystals owing to negligible extinction effects and minimal...... peak overlap. Additionally, it offers the opportunity for collecting data on a single scale. For charge densities studies, the critical task is to recover accurate and bias-free structure factors from the diffraction pattern. This is the focal point of the present study, scrutinizing the performance...
Liquid crystal based optical platform for the detection of Pb2+ ions using NiFe2O4 nanoparticles

Directory of Open Access Journals (Sweden)

Saman Zehra

2018-06-01

Full Text Available A simple, sensitive, selective and real time detection protocol was developed for Pb2+ ions in water using liquid crystals (LCs. In this method, NiFe2O4 nanoparticles were synthesized using chemical co-precipitation method. Crystallite size, morphological, functional groups and magnetization studies were confirmed using X-ray diffraction, Scanning Electron Microscopy, and Fourier transform infrared spectroscopy techniques, respectively. The nanoparticles were mono dispersed with average particle size of 20 ± 2 nm. The surfactant stabilized magnetic nanoparticles were incubated in liquid crystal based sensor system for the detection of Pb+2 ions. The bright to dark transition of LC was observed through optical microscope. When this system was further immersed with a solution containing Pb2+ ions, it caused homeotropic to planar orientation of LC. This interaction is attributed to the presence of abundant hydroxyl groups in such as M-OH, Fe-OH on the surface of spinel ferrites nanoparticles. These groups interact with metal ions at aqueous interface, causing disruption in LCs orientation giving bright texture. This sensor showed higher selectivity towards Pb2+ ions. The detection limit was estimated to be 100 ppb. The cheap and effective protocol reported here should make promising development of LC based sensor for lead ion detection. Keywords: Chemical co-precipitation method, Fourier transform infrared spectroscopy, Liquid crystals, Nanoparticles, Sensor, X-ray diffraction
Improved X-ray diffraction from Bacillus megaterium penicillin G acylase crystals through long cryosoaking dehydration

International Nuclear Information System (INIS)

Rojviriya, Catleya; Pratumrat, Thunyaluck; Saper, Mark A.; Yuvaniyama, Jirundon

2011-01-01

Penicillin G acylase from the Gram-positive bacterium B. megaterium was crystallized and X-ray diffraction from these crystals could be substantially improved by slight dehydration through a long cryo-soak. Penicillin G acylase from Bacillus megaterium (BmPGA) is currently used in the pharmaceutical industry as an alternative to PGA from Escherichia coli (EcPGA) for the hydrolysis of penicillin G to produce 6-aminopenicillanic acid (6-APA), a penam nucleus for semisynthetic penicillins. Despite the significant differences in amino-acid sequence between PGAs from Gram-positive and Gram-negative bacteria, a representative PGA structure of Gram-positive origin has never been reported. In this study, crystallization and diffraction studies of BmPGA are described. Poor diffraction patterns with blurred spots at higher resolution were typical for BmPGA crystals cryocooled after a brief immersion in cryoprotectant solution. Overnight soaking in the same cryo-solution substantially improved both the mosaicity and resolution limit through the establishment of a new crystal-packing equilibrium. A crystal of BmPGA diffracted X-rays to 2.20 Å resolution and belonged to the monoclinic space group P2 1 with one molecule of BmPGA in the asymmetric unit
Determining the diffraction properties of a cylindrically bent KAP(001) crystal from 1 to 5 keV

Energy Technology Data Exchange (ETDEWEB)

Haugh, Michael [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Lee, Joshua [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Jacoby, Kenneth [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Christensen, C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Loisel, G. [National Security Technologies, LLC. (NSTec), Mercury, NV (United States), Livermore Operations

2015-08-31

Various crystals are used for the dispersive component of X-ray spectrometers. The crystals are usually bent to meet the desired measurement needs, such as focusing. The bending can change the crystal diffraction properties, thus altering the spectrometer throughput and resolving power. This work concerns measuring the diffraction properties of a potassium acid phthalate (001) [KAP(001)] crystal bent into a circular cylinder segment. The measurement methods using a diode source and a synchrotron source are described. The multi-lamellar model for calculating the diffraction properties of a bent crystal is described. The measurement results are compared to the multi-lamellar model and show qualitative agreement. The measurements show how to make the multi-lamellar calculations a useful estimate. A method is given to make useful estimates of the diffraction properties of the KAP(001) crystal bent into a circular cylinder segment.
Diffraction imaging study of the phase coexistence around the triple point in MnP

International Nuclear Information System (INIS)

Medrano, C.; Pernot, E.; Espeso, J.I.; Boller, E.; Lorut, F.; Baruchel, J.

2001-01-01

The coexistence of the helimagnetic, ferromagnetic and fan phases in the neighborhood of the triple point is investigated by real-time Bragg diffraction imaging in a (0 0 1) MnP crystal. When increasing the field while retaining the heli-ferromagnetic coexistence, the nucleation of the fan phase occurs inside the present interface. The shapes and orientations of the heli-ferromagnetic and fan-helimagnetic interfaces can be understood by considering the corresponding elastic and/or magnetostatic energy. The ferromagnetic-fan thick interface, on the contrary, suggests the existence of intermediate states
Liquid Crystal photonic Bandgap Fiber Devices

DEFF Research Database (Denmark)

Wei, Lei

In this Ph.D. thesis, an experimental investigation of liquid crystal photonic bandgap (LCPBG) fiber devices and applications is presented. Photonic crystal fibers (PCFs) consist of a cladding microstructure with periodic index variations and a core defined by a defect of the structure. The prese......In this Ph.D. thesis, an experimental investigation of liquid crystal photonic bandgap (LCPBG) fiber devices and applications is presented. Photonic crystal fibers (PCFs) consist of a cladding microstructure with periodic index variations and a core defined by a defect of the structure...... of each LCPBG fiber. Finally, the applications for LCPBG fiber devices based on the on-chip platform design have been demonstrated in realizing microwave true-time delay and creating an electrically tunable fiber laser. Referatet mailes...
Crystallization and preliminary X-ray diffraction analysis of the middle domain of Paip1

International Nuclear Information System (INIS)

Kanaan, Ahmad Seif; Frank, Filipp; Maedler-Kron, Chelsea; Verma, Karan; Sonenberg, Nahum; Nagar, Bhushan

2009-01-01

The crystallization of the putative MIF4G domain of Paip1 is described. The crystals belonged to the monoclinic space group P2 1 and diffracted X-rays to beyond 2.2 Å resolution. The poly(A)-binding protein (PABP) simultaneously interacts with the poly(A) tail of mRNAs and the scaffolding protein eIF4G to mediate mRNA circularization, resulting in stimulation of protein translation. PABP is regulated by the PABP-interacting protein Paip1. Paip1 is thought to act as a translational activator in 5′ cap-dependent translation by interacting with PABP and the initiation factors eIF4A and eIF3. Here, the crystallization and preliminary diffraction analysis of the middle domain of Paip1 (Paip1M), which produces crystals that diffract to a resolution of 2.2 Å, are presented
Liquid crystal colloids

CERN Document Server

Muševič, Igor

2017-01-01

This book brings together the many concepts and discoveries in liquid crystal colloids contributed over the last twenty years and scattered across numerous articles and book chapters. It provides both a historical overview of the development of the field and a clear perspective on the future applications in photonics. The book covers all phenomena observed in liquid crystal colloids with an emphasis on experimental tools and applications of topology in condensed matter, as well as practical micro-photonics applications. It includes a number of spectacular manifestations of new topological phenomena not found or difficult to observe in other systems. Starting from the early works on nematic colloids, it explains the basics of topological defects in ordered media, charge and winding, and the elastic forces between colloidal particles in nematics. Following a detailed description of experimental methods, such as optical tweezing and particle tracking, the book eases the reader into the theoretical part, which de...
Production, crystallization and preliminary X-ray diffraction analysis of the allergen Can f 2 from Canis familiaris

International Nuclear Information System (INIS)

Madhurantakam, Chaithanya; Nilsson, Ola B.; Jönsson, Klas; Grönlund, Hans; Achour, Adnane

2009-01-01

The recombinant form of the allergen Can f 2 from C. familiaris was produced, isolated and crystallized in two different forms. Preliminary X-ray diffraction analyses are reported for the two crystal forms of Can f 2. The allergen Can f 2 from dog (Canis familiaris) present in saliva, dander and fur is an important cause of allergic sensitization worldwide. Here, the production, isolation, crystallization and preliminary X-ray diffraction analysis of two crystal forms of recombinant Can f 2 are reported. The first crystal form belonged to space group C222, with unit-cell parameters a = 68.7, b = 77.3, c = 65.1 Å, and diffracted to 1.55 Å resolution, while the second crystal form belonged to space group C2, with unit-cell parameters a = 75.7, b = 48.3, c = 68.7 Å, β = 126.5°, and diffracted to 2.1 Å resolution. Preliminary data analysis indicated the presence of a single molecule in the asymmetric unit for both crystal forms
Mesomorphic and structural properties of liquid crystal possessing a chiral lactate unit

Czech Academy of Sciences Publication Activity Database

Das, B.; Pramanik, A.; Das, M.K.; Bubnov, Alexej; Hamplová, Věra; Kašpar, Miroslav

2012-01-01

Roč. 1013, APR (2012), s. 119-125 ISSN 0022-2860 R&D Projects: GA AV ČR IAA100100911; GA AV ČR(CZ) GA202/09/0047; GA ČR(CZ) GAP204/11/0723 Grant - others:RFASI(RU) 02.740.11.5166 Institutional research plan: CEZ:AV0Z10100520 Keywords : liquid crystals * phase transition * N*-TGB A * x-ray diffraction * differential scanning calorimetry Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.404, year: 2012 http://www.sciencedirect.com/science/article/pii/S0022286012000440
Liquid crystals beyond displays chemistry, physics, and applications

CERN Document Server

Li, Quan

2012-01-01

The chemistry, physics, and applications of liquid crystals beyond LCDs Liquid Crystals (LCs) combine order and mobility on a molecular and supramolecular level. But while these remarkable states of matter are most commonly associated with visual display technologies, they have important applications for a variety of other fields as well. Liquid Crystals Beyond Displays: Chemistry, Physics, and Applications considers these, bringing together cutting-edge research from some of the most promising areas of LC science. Featuring contributions from respected researchers from around the globe, th
Liquid nitrogen dewar for protein crystal growth

Science.gov (United States)

2001-01-01

Gaseous Nitrogen Dewar apparatus developed by Dr. Alex McPherson of the University of California, Irvine for use aboard Mir and the International Space Station allows large quantities of protein samples to be crystallized in orbit. The specimens are contained either in plastic tubing (heat-sealed at each end). Biological samples are prepared with a precipitating agent in either a batch or liquid-liquid diffusion configuration. The samples are then flash-frozen in liquid nitrogen before crystallization can start. On orbit, the Dewar is placed in a quiet area of the station and the nitrogen slowly boils off (it is taken up by the environmental control system), allowing the proteins to thaw to begin crystallization. The Dewar is returned to Earth after one to four months on orbit, depending on Shuttle flight opportunities. The tubes then are analyzed for crystal presence and quality
A numerical method for eigenvalue problems in modeling liquid crystals

Energy Technology Data Exchange (ETDEWEB)

Baglama, J.; Farrell, P.A.; Reichel, L.; Ruttan, A. [Kent State Univ., OH (United States); Calvetti, D. [Stevens Inst. of Technology, Hoboken, NJ (United States)

1996-12-31

Equilibrium configurations of liquid crystals in finite containments are minimizers of the thermodynamic free energy of the system. It is important to be able to track the equilibrium configurations as the temperature of the liquid crystals decreases. The path of the minimal energy configuration at bifurcation points can be computed from the null space of a large sparse symmetric matrix. We describe a new variant of the implicitly restarted Lanczos method that is well suited for the computation of extreme eigenvalues of a large sparse symmetric matrix, and we use this method to determine the desired null space. Our implicitly restarted Lanczos method determines adoptively a polynomial filter by using Leja shifts, and does not require factorization of the matrix. The storage requirement of the method is small, and this makes it attractive to use for the present application.
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
Lyotropic liquid crystal based on zinc oxide nanoparticles obtained by microwave solvothermal synthesis

Energy Technology Data Exchange (ETDEWEB)

Omelchenko, M.M., E-mail: momelchenko@chem.uw.edu.pl [Department of Chemistry, Warsaw University, Al. Zwirki i Wigury 101, 02-089, Warsaw (Poland); Wojnarowicz, J. [Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, Warsaw, 01-142 (Poland); Salamonczyk, M. [Department of Chemistry, Warsaw University, Al. Zwirki i Wigury 101, 02-089, Warsaw (Poland); Lojkowski, W. [Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, Warsaw, 01-142 (Poland)

2017-05-01

Abstract: The ZnO nanoparticles, obtained by microwave solvothermal synthesis, were used for the liquid crystal phase preparation. The structure of the material was investigated by X-ray diffraction (XRD), helium pycnometry, specific surface area (SSA), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM). The stability of aqueous suspensions was monitored by Multiple Light Scattering (MLS) technique and the average agglomerate size in suspensions was obtained by dynamic light scattering (DLS) technique. The lyotropic columnar hexagonal phase was formed by doping ZnO nanoparticles into the cetylpiridinium chloride/water/hexanol system. The structure of this phase was confirmed by x-ray diffraction. The luminescent properties of the LC phase were compared with properties of ZnO nanoparticles isolated in solution and analogues lyotropic system without nanoparticles.

Ultrasonic absorption and velocity dispersion of binary mixture liquid crystal MBBA/EBBA

International Nuclear Information System (INIS)

Choi, K.

1979-01-01

The effect of phase transitions and the partial magnetic alignment for liquid crystal molecules on the ultrasonic absorption and velocity dispersion has been investigated. The binary mixture of Shiff base liquid crystals MBBA/EBBA (55:45 mole %) showed anomalous ultrasonic absorption and velocity dispersion at eutectic (Tsub(m) = -20 0 C) and clearing point (Tsub(c) = 50 0 C) at the frequency range of 5 MHz, 10MHz, 15MHz and 30 MHz. The experimental data were analyzed in terms of relaxation time and Fixman theory. The anisotropy of the propagation velocity due to the magnetic alignment was about 0.9% (the deviation between velocities propagating parallel and perpendicular to the applied field). (author)
Crystallization and X-ray diffraction analysis of dihydropyrimidinase from Saccharomyces kluyveri

International Nuclear Information System (INIS)

Dobritzsch, Doreen; Andersen, Birgit; Piškur, Jure

2005-01-01

Dihydropyrimidinase from the yeast S. kluyveri was crystallized by vapour diffusion. The crystals belong to space group P2 1 (unit-cell parameters a = 91.0, b = 73.0, c = 161.4 Å, β = 91.4°) and diffracted to 2.6 Å resolution. Dihydropyrimidinase (EC 3.5.2.2) catalyzes the second step in the reductive pathway of pyrimidine degradation, the hydrolysis of 5,6-dihydrouracil and 5,6-dihydrothymine to the corresponding N-carbamylated β-amino acids. Crystals of the recombinant enzyme from the yeast Saccharomyces kluyveri diffracting to 2.6 Å at a synchrotron-radiation source have been obtained by the hanging-drop vapour-diffusion method. They belong to space group P2 1 (unit-cell parameters a = 91.0, b = 73.0, c = 161.4 Å, β = 91.4°), with one homotetramer per asymmetric unit
Moessbauer radiation dynamical diffraction in crystals being subjected to the action of external variable fields

International Nuclear Information System (INIS)

Baryshevskii, V.G.; Skadorov, V.V.

1986-01-01

A dynamical theory is developed of the Moessbauer radiation diffraction by crystals being subjected to an variable external field action. Equations describing the dynamical diffraction by nonstationary crystals are obtained. It is shown that the resonant interaction between Moessbauer radiation and shift field induced in the crystal by a variable external field giving rise to an effective conversion of the incident wave into a wave with changed frequency. (author)
Lyotropic chromonic liquid crystals: From viscoelastic properties to living liquid crystals

Science.gov (United States)

Zhou, Shuang

Lyotropic chromonic liquid crystal (LCLC) represents a broad range of molecules, from organic dyes and drugs to DNA, that self-assemble into linear aggregates in water through face-to-face stacking. These linear aggregates of high aspect ratio are capable of orientational order, forming, for example nematic phase. Since the microscopic properties (such as length) of the chromonic aggregates are results of subtle balance between energy and entropy, the macroscopic viscoelastic properties of the nematic media are sensitive to change of external factors. In the first part of this thesis, by using dynamic light scattering and magnetic Frederiks transition techniques, we study the Frank elastic moduli and viscosity coefficients of LCLC disodium cromoglycate (DSCG) and sunset yellow (SSY) as functions of concentration c , temperature T and ionic contents. The elastic moduli of splay (K1) and bend (K3) are in the order of 10pN, about 10 times larger than the twist modulus (K2). The splay modulus K1 and the ratio K1/K3 both increase substantially as T decreases or c increases, which we attribute to the elongation of linear aggregates at lower T or higher c . The bend viscosity is comparable to that of thermotropic liquid crystals, while the splay and twist viscosities are several orders of magnitude larger, changing exponentially with T . Additional ionic additives into the system influence the viscoelastic properties of these systems in a dramatic and versatile way. For example, monovalent salt NaCl decreases bend modulus K3 and increases twist viscosity, while an elevated pH decreases all the parameters. We attribute these features to the ion-induced changes in length and flexibility of building units of LCLC, the chromonic aggregates, a property not found in conventional thermotropic and lyotropic liquid crystals form by covalently bound units of fixed length. The second part of the thesis studies a new active bio-mechanical hybrid system called living liquid crystal
Advanced x-ray stress analysis method for a single crystal using different diffraction plane families

International Nuclear Information System (INIS)

Imafuku, Muneyuki; Suzuki, Hiroshi; Sueyoshi, Kazuyuki; Akita, Koichi; Ohya, Shin-ichi

2008-01-01

Generalized formula of the x-ray stress analysis for a single crystal with unknown stress-free lattice parameter was proposed. This method enables us to evaluate the plane stress states with any combination of diffraction planes. We can choose and combine the appropriate x-ray sources and diffraction plane families, depending on the sample orientation and the apparatus, whenever diffraction condition is satisfied. The analysis of plane stress distributions in an iron single crystal was demonstrated combining with the diffraction data for Fe{211} and Fe{310} plane families
Molecular dynamics simulations of liquid crystals at interfaces

International Nuclear Information System (INIS)

Shield, Mark

2002-01-01

Molecular dynamics simulations of an atomistic model of 4-n-octyl-4'-cyanobiphenyl (8CB) were performed for thin films of 8CB on solid substrates (a pseudopotential representation of the molecular topography of the (100) crystal surface of polyethylene (PE), a highly ordered atomistic model of a pseudo-crystalline PE surface and an atomistic model of a partially orientated film of PE), free standing thin films of 8CB and 8CB droplets in a hexagonal pit. The systems showed strong homeotropic anchoring at the free volume interface and planar anchoring at the solid interface whose strength was dependent upon the surface present. The free volume interface also demonstrated weak signs of smectic wetting of the bulk. Simulations of thin free standing films of liquid crystals showed the ordered nature of the liquid crystals at the two free volume interfaces can be adopted by the region of liquid crystal molecules between the homeotropic layer at each interface only if there is a certain number of liquid crystal molecules present. The perpendicular anchoring imposed by the free volume interface and the solid interface for the thin films on the solid substrates resulted in some evidence for the liquid crystal director undergoing a continual rotation at low temperatures and a definite discontinuous change at higher temperatures. The liquid crystal alignment imparted by these substrates was found to depend upon the topography of the surface and not the direction of the polymer chains in the substrate. The liquid crystal was found to order via an epitaxy-like mechanism. The perpendicular anchoring results in a drop in the order - disorder transition temperature for the molecules in the region between the homeotropic layer at the free volume interface and the planar layers at the solid interface. An increase in the size of this region does not alter the transition temperature. The shape of the liquid crystal molecules is dependent upon the degree of order and thus the nematic
Liquid crystal display

International Nuclear Information System (INIS)

Takami, K.

1981-01-01

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

International Nuclear Information System (INIS)

Kim Chir Sen; Nitts, V.V.

1985-01-01

The neutron diffraction by the mosaic single crystal with size of crystallites sufficient to achieve the primary extinction saturation is considered. Two cases where the proportionality between the reflection intensity and the structure amplitude is performed are analysed. Such a dependence is convenient for structure investigations. The difficulties connected with the accounting of the extinction are eliminated considerably
Far-field and Fresnel Liquid Crystal Geometric Phase Holograms via Direct-Write Photo-Alignment

Directory of Open Access Journals (Sweden)

Xiao Xiang

2017-12-01

Full Text Available We study computer-generated geometric-phase holograms (GPHs realized by photo-aligned liquid crystals, in both simulation and experiment. We demonstrate both far-field and Fresnel holograms capable of producing far-field and near-field images with preserved fidelity for all wavelengths. The GPHs are fabricated by patterning a photo-alignment layer (PAL using a direct-write laser scanner and coating the surface with a polymerizable liquid crystal (i.e., a reactive mesogen. We study various recording pixel sizes, down to 3 μm, that are easily recorded in the PAL. We characterize the fabricated elements and find good agreement with theory and numerical simulation. Because of the wavelength independent geometric phase, the (phase fidelity of the replay images is preserved for all wavelengths, unlike conventional dynamic phase holograms. However, governed by the diffraction equation, the size and location of a reconstructed image depends on the replay wavelength for far-field and near-field GPHs, respectively. These offer interesting opportunities for white-light holography.
Small-angle neutron scattering technique in liquid crystal studies

International Nuclear Information System (INIS)

Shahidan Radiman

2005-01-01

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

Science.gov (United States)

1994-11-10

materials. In addition to the nonlinear studies, a separate subproject involving linear properties 0 of polymer dispersed liquid crystals in the infrared ...The horizontal axis represents on-axis laser intensity Io, defined as Io = 2P/( ww2 ), where P is the power and u0 is the beam waist. As can be seen in...I * 9 IR Shutter 1 Included in our original contract was a separate project to evaluate the use of liquid crystal composites in infrared shattering
Measurement of the velocity of sound in crystals by pulsed neutron diffraction

International Nuclear Information System (INIS)

Willis, B.T.M.; Carlile, C.J.; Ward, R.C.; David, W.I.F.; Johnson, M.W.

1986-03-01

The diffraction method of observing elementary excitations in crystals has been applied to the study of one-phonon thermal diffuse scattering from pyrolytic graphite on a high resolution pulsed neutron diffractometer. The variation of the phase velocity of sound as a function of direction in the crystal and efficient method of determining sound velocities in crystals under extreme conditions. (author)
Interpretation of the shape of electron diffraction spots from small polyhedral crystals by means of the crystal shape amplitude

International Nuclear Information System (INIS)

Neumann, W.; Hofmeister, H.; Heydenreich, J.; Komrska, J.

1988-01-01

The influence of the crystal shape on the fine structure of transmission electron diffraction (TED) patterns described by the crystal shape amplitude is discussed. A general algebraic expression for the crystal shape amplitude of any crystal polyhedron is used for computing the intensity distribution of TED reflections. The computer simulation method is applied to the analysis of the fine structure of TED patterns of small gold and palladium crystals having octahedral and tetrahedral habits. (orig.)
Electrically modulated transparent liquid crystal-optical grating projection

DEFF Research Database (Denmark)

Buss, Thomas; Smith, Cameron; Kristensen, Anders

2013-01-01

A transparent, fully integrated electrically modulated projection technique is presented based on light guiding through a thin liquid crystal layer covering sub-wavelength gratings. The reported device operates at 10 V with response times of 4.5 ms. Analysis of the liquid crystal alignment shows...
Liquid-crystal intraocular adaptive lens with wireless control

NARCIS (Netherlands)

Simonov, A.N.; Vdovine, G.V.; Loktev, M.

2007-01-01

We present a prototype of an adaptive intraocular lens based on a modal liquid-crystal spatial phase modulator with wireless control. The modal corrector consists of a nematic liquid-crystal layer sandwiched between two glass substrates with transparent low- and high-ohmic electrodes, respectively.
Soap, science, and flat-screen TVs a history of liquid crystals

CERN Document Server

Dunmur, David

2011-01-01

The terms 'liquid crystal' or 'liquid crystal display' (LCD) are well-known in the context of flat-screen televisions, but the properties and history of liquid crystals are little understood. This book tells the story of liquid crystals, from their controversial discovery at the end of the nineteenth century, to their eventual acceptance as another state of matter to rank alongside gases, liquids and solids. As their story unfolds, the scientists involved and their works are put into illuminating broader socio-political contexts. In recent years, liquid crystals have had a major impact on the display industry, culminating in the now widely available flat-screen televisions; this development is described in detail over three chapters, and the basic science behind it is explained in simple terms accessible to a general reader. New applications of liquid crystals in materials, bio-systems, medicine and technology are also explained.
Alkyltributylphosphonium chloride ionic liquids: synthesis, physicochemical properties and crystal structure.

Science.gov (United States)

Adamová, Gabriela; Gardas, Ramesh L; Nieuwenhuyzen, Mark; Puga, Alberto V; Rebelo, Luís Paulo N; Robertson, Allan J; Seddon, Kenneth R

2012-07-21

A series of alkyltributylphosphonium chloride ionic liquids, prepared from tributylphosphine and the respective 1-chloroalkane, C(n)H(2n+1)Cl (where n = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12 or 14), is reported. This work is a continuation of an extended series of tetraalkylphosphonium ionic liquids, where the focus is on the variability of n and its impact on the physical properties, such as melting points/glass transitions, thermal stability, density and viscosity. Experimental density and viscosity data were interpreted using QPSR and group contribution methods and the crystal structure of propyl(tributyl)phosphonium chloride is detailed.
Hybrid silica luminescent materials based on lanthanide-containing lyotropic liquid crystal with polarized emission

Energy Technology Data Exchange (ETDEWEB)

Selivanova, N.M., E-mail: natsel@mail.ru [Kazan National Research Technological University, 68 Karl Marx Str., Kazan 420015 (Russian Federation); Vandyukov, A.E.; Gubaidullin, A.T. [A.E. Arbuzov Institute of Organic and Physical Chemistry of the Kazan Scientific Center of the Russian Academy of Sciences, 8 Acad. Arbuzov Str., Kazan 420088 (Russian Federation); Galyametdinov, Y.G. [Kazan National Research Technological University, 68 Karl Marx Str., Kazan 420015 (Russian Federation)

2014-11-14

This paper represents the template method for synthesis of hybrid silica films based on Ln-containing lyotropic liquid crystal and characterized by efficient luminescence. Luminescence films were prepared in situ by the sol–gel processes. Lyotropic liquid crystal (LLC) mesophases C{sub 12}H{sub 25}O(CH{sub 2}CH{sub 2}O){sub 10}H/Ln(NO{sub 3}){sub 3}·6H{sub 2}O/H{sub 2}O containing Ln (III) ions (Dy, Tb, Eu) were used as template. Polarized optical microscopy, X-ray powder diffraction, and FT-IR-spectroscopy were used for characterization of liquid crystal mesophases and hybrid films. The morphology of composite films was studied by the atomic force microscopy method (AFM). The optical properties of the resulting materials were evaluated. It was found that hybrid silica films demonstrate significant increase of their lifetime in comparison with an LLC system. New effects of linearly polarized emission revealed for Ln-containing hybrid silica films. Polarization in lanthanide-containing hybrid composites indicates that silica precursor causes orientation of emitting ions. - Highlights: • We suggest a new simple approach for creating luminescence hybrid silica films. • Ln-containing hybrid silica films demonstrate yellow, green and red emissions. • Tb(III)-containing hybrid film have a high lifetime. • We report effects of linearly polarized emission in hybrid film.
Crystals of DhaA mutants from Rhodococcus rhodochrous NCIMB 13064 diffracted to ultrahigh resolution: crystallization and preliminary diffraction analysis

International Nuclear Information System (INIS)

Stsiapanava, Alena; Koudelakova, Tana; Lapkouski, Mikalai; Pavlova, Martina; Damborsky, Jiri; Kuta Smatanova, Ivana

2008-01-01

Three mutants of the haloalkane dehalogenase DhaA derived from R. rhodochrous NCIMB 13064 were crystallized and diffracted to ultrahigh resolution. The enzyme DhaA from Rhodococcus rhodochrous NCIMB 13064 belongs to the haloalkane dehalogenases, which catalyze the hydrolysis of haloalkanes to the corresponding alcohols. The haloalkane dehalogenase DhaA and its variants can be used to detoxify the industrial pollutant 1,2,3-trichloropropane (TCP). Three mutants named DhaA04, DhaA14 and DhaA15 were constructed in order to study the importance of tunnels connecting the buried active site with the surrounding solvent to the enzymatic activity. All protein mutants were crystallized using the sitting-drop vapour-diffusion method. The crystals of DhaA04 belonged to the orthorhombic space group P2 1 2 1 2 1 , while the crystals of the other two mutants DhaA14 and DhaA15 belonged to the triclinic space group P1. Native data sets were collected for the DhaA04, DhaA14 and DhaA15 mutants at beamline X11 of EMBL, DESY, Hamburg to the high resolutions of 1.30, 0.95 and 1.15 Å, respectively
Crystallization and preliminary X-ray diffraction analysis of red clover necrotic mosaic virus

International Nuclear Information System (INIS)

Martin, Stanton L.; Guenther, Richard H.; Sit, Tim L.; Swartz, Paul D.; Meilleur, Flora; Lommel, Steven A.; Rose, Robert B.

2010-01-01

Virions of red clover necrotic mosaic virus have been purified and crystallized. The space group was determined to be I23, with unit-cell parameter a = 377.8 Å. The crystals diffracted to 4 Å resolution. Red clover necrotic mosaic virus (RCNMV) is a species that belongs to the Tombusviridae family of plant viruses with a T = 3 icosahedral capsid. RCNMV virions were purified and were crystallized for X-ray analysis using the hanging-drop vapor-diffusion method. Self-rotation functions and systematic absences identified the space group as I23, with two virions in the unit cell. The crystals diffracted to better than 4 Å resolution but were very radiation-sensitive, causing rapid decay of the high-resolution reflections. The data were processed to 6 Å in the analysis presented here

Simulations of X-ray diffraction of shock-compressed single-crystal tantalum with synchrotron undulator sources.

Science.gov (United States)

Tang, M X; Zhang, Y Y; E, J C; Luo, S N

2018-05-01

Polychromatic synchrotron undulator X-ray sources are useful for ultrafast single-crystal diffraction under shock compression. Here, simulations of X-ray diffraction of shock-compressed single-crystal tantalum with realistic undulator sources are reported, based on large-scale molecular dynamics simulations. Purely elastic deformation, elastic-plastic two-wave structure, and severe plastic deformation under different impact velocities are explored, as well as an edge release case. Transmission-mode diffraction simulations consider crystallographic orientation, loading direction, incident beam direction, X-ray spectrum bandwidth and realistic detector size. Diffraction patterns and reciprocal space nodes are obtained from atomic configurations for different loading (elastic and plastic) and detection conditions, and interpretation of the diffraction patterns is discussed.
Simulations of X-ray diffraction of shock-compressed single-crystal tantalum with synchrotron undulator sources

Energy Technology Data Exchange (ETDEWEB)

Tang, M. X.; Zhang, Y. Y.; E, J. C.; Luo, S. N.

2018-04-24

Polychromatic synchrotron undulator X-ray sources are useful for ultrafast single-crystal diffraction under shock compression. Here, simulations of X-ray diffraction of shock-compressed single-crystal tantalum with realistic undulator sources are reported, based on large-scale molecular dynamics simulations. Purely elastic deformation, elastic–plastic two-wave structure, and severe plastic deformation under different impact velocities are explored, as well as an edge release case. Transmission-mode diffraction simulations consider crystallographic orientation, loading direction, incident beam direction, X-ray spectrum bandwidth and realistic detector size. Diffraction patterns and reciprocal space nodes are obtained from atomic configurations for different loading (elastic and plastic) and detection conditions, and interpretation of the diffraction patterns is discussed.
Single-crystal neutron diffraction at the Australian Replacement Research Reactor

International Nuclear Information System (INIS)

Klooster, W.T.

2001-01-01

The purpose of the workshop was to: identify the future needs and opportunities for single-crystal neutron diffraction, and specify instrument requirements. important number of experiments. The conclusion of the workshop deliberation was that Australia has a diverse community of users of single-crystal neutron diffraction. A (quasi)-Laue image-plate diffractometer allows the fastest throughput by far, but would exclude an important number of experiments. Most of these could be covered by the additional possibility to locate the image-plate detector on a monochromatic beam. Therefore it was recommend both a white thermal beam and a monochromatic beam (λ= 1 to 2.4 Angstroms) for an image-plate detector. At little additional cost the existing 2TanA instrument could be located semi-permanently on the same monochromatic beam, thus offering three quite different types of single-crystal instruments. Small improvements could be made to the 2TanA instrument to cater for the remaining experiments not suited to an image-plate diffractometer: exchange of the Eulerian cradle for an automated tilt goniometer for extremely bulky sample environment (cryomagnets, large pressure cells), optional larger area detector, analyser crystal. It was recommended that an Instrument Advisory Team will be assembled, and will help in specifying, designing and commissioning the instrument
Large Electro-Optic Kerr-Effect in Ionic Liquid Crystals: Connecting Features of Liquid Crystals and Polyelectrolytes.

Science.gov (United States)

Schlick, Michael Christian; Kapernaum, Nadia; Neidhardt, Manuel; Wöhrle, Tobias; Stöckl, Yannick; Laschat, Sabine; Gießelmann, Frank

2018-06-06

The electro-optic Kerr effect in the isotropic phase of two ionic liquid crystals (ILCs) is investigated and compared to the Kerr effect in non-ionic liquid crystals (LCs) with same phase sequences, namely direct isotropic to hexagonal columnar transitions and direct isotropic to smectic-A transitions. Up to electric field amplitudes of some 106 V m-1, the optical birefringence induced in the isotropic phases follows Kerr's law and strongly increases when the temperature approaches the transition temperature into the particular liquid crystalline phase. Close to the transition, maximum Kerr constants in the order of 10-11 m V-2 are found, which are more than ten times higher than the Kerr constant of nitrobenzene, a strongly dipolar fluid with a huge Kerr effect applied in optical shutters and phase modulators. In comparison to their non-ionic LC counterparts the Kerr effect in ILCs is found to be enhanced in magnitude, but slowed-down in speed, showing rise times in the order of ten milliseconds. These remarkable differences are attributed to the presence of counterion polarization well-known from complex ionic fluids such as polyelectrolytes or ionic micellar solutions. ILCs thus combine the Kerr effect features of liquid crystals and complex ionic fluids. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Anisotropic light diffraction in crystals with a large acoustic-energy walk-off

Science.gov (United States)

Balakshy, V. I.; Voloshin, A. S.; Molchanov, V. Ya.

2014-11-01

The influence of energy walk-off in an acoustic beam on the characteristic of anisotropic Bragg diffraction of light has been investigated by the example of paratellurite crystal. The angular and frequency characteristics of acousto-optic diffraction have been calculated in wide ranges of ultrasound frequencies and Bragg angles using the modified Raman-Nath equations. It is shown that the walk-off of an acoustic beam may change (either widen or narrow) significantly the frequency and angular ranges. The calculation results have been experimentally checked on an acousto-optic cell made of 10.5°-cut paratellurite crystal.
Crystallization and preliminary X-ray diffraction analysis of diaminopimelate epimerase from Escherichia coli

International Nuclear Information System (INIS)

Hor, Lilian; Dobson, Renwick C. J.; Dogovski, Con; Hutton, Craig A.; Perugini, Matthew A.

2009-01-01

Diaminopimelate (DAP) epimerase, an enzyme in the lysine-biosynthetic pathway, is a promising target for antibiotic development against pathogenic bacteria. Here, the cloning, expression, purification, crystallization and preliminary diffraction analysis of DAP epimerase from E. coli are reported. Diaminopimelate (DAP) epimerase (EC 5.1.1.7) catalyzes the penultimate step of lysine biosynthesis in bacteria and plants, converting l,l-diaminopimelate to meso-diaminopimelate. Here, the cloning, expression, purification, crystallization and preliminary X-ray diffraction analysis of DAP epimerase from Escherichia coli are presented. Crystals were obtained in space group P4 1 2 1 2 and diffracted to 2.0 Å resolution, with unit-cell parameters a = b = 89.4, c = 179.6 Å. Molecular replacement was conducted using Bacillus anthracis DAP epimerase as a search model and showed the presence of two molecules in the asymmetric unit, with an initial R free of 0.456 and R work of 0.416
UV response on dielectric properties of nano nematic liquid crystal

Directory of Open Access Journals (Sweden)

Kamal Kumar Pandey

2018-03-01

Full Text Available In this work, we investigate the effect of UV light irradiation on the dielectric parameters of nematic liquid crystal (5CB and ZnO nanoparticles dispersed liquid crystal. With addition of nanoparticles in nematic LC are promising new materials for a variety of application in energy harvesting, displays and photonics including the liquid crystal laser. To realize many applications, however we optimize the properties of liquid crystal and understand how the UV light irradiation interact the nanoparticles and LC molecules in dispersed/doped LC. The dielectric permittivity and loss factor have discussed the pure nematic LC and dispersed/doped system after, during and before UV light exposure. The dielectric relaxation spectroscopy was carried out in the frequency range 100 Hz–10 MHz in the nematic mesophase range. Keywords: Dielectric permittivity, Relaxation frequency, Nematic liquid crystal, UV light irradiation
Liquid crystals: a new topic in physics for undergraduates

International Nuclear Information System (INIS)

Pavlin, Jerneja; Čepič, Mojca; Vaupotič, Nataša

2013-01-01

This paper presents a teaching module about liquid crystals. Since liquid crystals are linked to everyday student experiences and are also a topic of current scientific research, they are an excellent candidate for a modern topic to be introduced into education. We show that liquid crystals can provide a pathway through several fields of physics such as thermodynamics, optics and electromagnetism. We discuss what students should learn about liquid crystals and what physical concepts they should know before considering them. In the presentation of the teaching module, which consists of a lecture and experimental work in a chemistry and physics laboratory, we focus on experiments on phase transitions, polarization of light, double refraction and colours. A pilot evaluation of the module was performed among pre-service primary school teachers who have no special preference for natural sciences. The evaluation shows that the module is very efficient in transferring knowledge. A prior study showed that the informally obtained pre-knowledge on liquid crystals of the first-year students from several different fields of study was negligible. Since social science students are the least interested in natural sciences, it can be expected that students in any study programme will on average achieve at least as good qualitative knowledge of phenomena related to liquid crystals as the group involved in the pilot study. (paper)
Young-Laplace equation for liquid crystal interfaces

Science.gov (United States)

Rey, Alejandro D.

2000-12-01

This letter uses the classical theories of liquid crystal physics to derive the Young-Laplace equation of capillary hydrostatics for interfaces between viscous isotropic (I) fluids and nematic liquid crystals (NLC's), and establishes the existence of four energy contributions to pressure jumps across these unusual anisotropic interfaces. It is shown that in addition to the usual curvature contribution, bulk and surface gradient elasticity, elastic stress, and anchoring energy contribute to pressure differentials across the interface. The magnitude of the effect is proportional to the elastic moduli of the NLC, and to the bulk and surface orientation gradients that may be present in the nematic phase. In contrast to the planar interface between isotropic fluids, flat liquid crystal interfaces support pressure jumps if elastic stresses, bulk and surface gradient energy, and/or anchoring energies are finite.
Synthesis of disk-rod-disk liquid crystal trimers by using click chemistry

Institute of Scientific and Technical Information of China (English)

无

2010-01-01

A series of disk-rod-disk liquid crystal trimers were synthesized.CuI-NEt3 catalyzed alkyne azide cycloaddition in toluene at room temperature connected two triphenylene discogens to a biphenyl rod-shaped mesogen.The trimers were characterized by using 1H NMR,IR,and high resolution mass spectrometry.The mesomorphic properties were investigated using polarized optical microscopy(POM) ,differential scanning calorimetry(DSC) ,and wide-angle X-ray diffraction.The results showed that the trimers exhibited rectangular columnar mesophase(Colr) .The length of the flexible spacer connecting the three segments has prominent influence on the phase transition temperatures of the trimers.
A high throughput liquid crystal light shutter for unpolarized light using polymer polarization gratings

Science.gov (United States)

Komanduri, Ravi K.; Lawler, Kris F.; Escuti, Michael J.

2011-05-01

We report on a broadband, diffractive, light shutter with the ability to modulate unpolarized light. This polarizer-free approach employs a conventional liquid crystal (LC) switch, combined with broadband Polarization Gratings (PGs) formed with polymer LC materials. The thin-film PGs act as diffractive polarizing beam-splitters, while the LC switch operates on both orthogonal polarization states simultaneously. As an initial experimental proof-of- concept for unpolarized light with +/-7° aperture, we utilize a commercial twisted-nematic LC switch and our own polymer PGs to achieve a peak transmittance of 80% and peak contrast ratio of 230:1. We characterize the optoelectronic performance, discuss the limitations, and evaluate its use in potential nonmechanical shutter applications (imaging and non-imaging).
Crystal structure solution of hydrides containing natEu from neutron powder diffraction data

International Nuclear Information System (INIS)

Kohlmann, H.

1999-01-01

Complete text of publication follows. The location of hydrogen in crystal structures of metal hydrides usually requires neutron diffraction data. Some elements, however, show excessively high absorption cross sections, σ a , for neutrons, thus making this technique seemingly impractical. Therefore no complete, refined crystal structure data of europium hydrides (σ a ( nat Eu) = .4530 barns at λ = 179.8 pm [1]) have been reported so far. It is shown that the absorption can be reduced to a value reasonable for neutron diffraction experiments by taking advantage of the wavelength dependence of σ a combined with the use of annular samples at advanced diffractometers. Neutron powder diffraction data on several nat Eu containing deuterides suitable for the ab initio crystal structure solution and refinement have been taken at D20 and D4 (ILL, Grenoble). The crystal chemistry of these europium hydrides, among them the two new compounds EuMg 2 H 6 and EuMgH 4 [2], is discussed. (author) [1] V.F. Sears, Neutron News 1992, 3, 26-37.; [2] H. Kohlmann, F. Gingl, T. Hansen, K. Yvon, Angew. Chem. Int. Ed. Eng. 1999, 38, accepted
The discovery of X-ray diffraction by crystals and its great impact on science

International Nuclear Information System (INIS)

Mai Zhenhong

2012-01-01

In April 1912, Friedrich, Knipping and Laue discovered X-ray diffraction in a CuSO 4 crystal. Later, Laue derived the famous Laue equations which explain the diffraction phenomenon. For this, Laue was awarded a Nobel Prize for Physics in 1914. In 1912 W. H. Bragg and W. L. Bragg received news of Laue 's discovery, and from X-ray diffraction experiments in a ZnS crystal they derived the famous Bragg equation. For this work, father and son were together awarded the Nobel Prize for Physics in 1915, To commemorate the 100th anniversary of the discovery of X-ray diffraction, this article reviews the important contributions of the early pioneers and their historic impact on science and technology worldwide. (author)
Purification, crystallization and preliminary diffraction studies of an ectromelia virus glutaredoxin

International Nuclear Information System (INIS)

Bacik, John-Paul; Brigley, Angela M.; Channon, Lisa D.; Audette, Gerald F.; Hazes, Bart

2005-01-01

Ectromelia virus glutaredoxin has been crystallized in the presence of the reducing agent DTT. A diffraction data set has been collected and processed to 1.8 Å resolution. Ectromelia, vaccinia, smallpox and other closely related viruses of the orthopoxvirus genus encode a glutaredoxin gene that is not present in poxviruses outside of this genus. The vaccinia glutaredoxin O2L has been implicated as the reducing agent for ribonucleotide reductase and may thus play an important role in viral deoxyribonucleotide synthesis. As part of an effort to understand nucleotide metabolism by poxviruses, EVM053, the O2L ortholog of the ectromelia virus, has been crystallized. EVM053 crystallizes in space group C222 1 , with unit-cell parameters a = 61.98, b = 67.57, c = 108.55 Å. Diffraction data have been processed to 1.8 Å resolution and a self-rotation function indicates that there are two molecules per asymmetric unit
H-Bond stabilized columnar discotic liquid crystals

NARCIS (Netherlands)

Paraschiv, I.

2007-01-01

Since 1977, more than 2300 publications on discotic (disk-like) liquid crystalline materials have appeared. Discotic liquid crystals, which usually consist of polyaromatic molecules surrounded by long peripheral alkyl tails, can form liquid crystalline mesophases in a wide temperature range. Within
Purification, crystallization and preliminary X-ray diffraction analysis of human Gadd45γ

International Nuclear Information System (INIS)

Zhang, Wenzheng; Zhao, Mingzhuo; Li, Jianhui; Li, Xuemei; Zeng, ZongHao; Rao, Zihe

2008-01-01

The human Gadd45γ protein has been crystallized as a prelude towards determination of its three-dimensional structure by X-ray crystallography. Gadd45, MyD118 and CR6 (also termed Gadd45α, Gadd45β and Gadd45γ, respectively) comprise a family of proteins that play important roles in negative growth control, maintenance of genomic stability, DNA repair, cell-cycle control and apoptosis. Recombinant human Gadd45γ and its selenomethionine derivative were expressed in an Escherichia coli expression system and purified; they were then crystallized using the hanging-drop vapour-diffusion method. Diffraction-quality crystals were grown at 291 K using PEG 3350 as precipitant. Using synchrotron radiation, the best diffraction data were collected to 2.3 Å resolution for native crystals at 100 K; selenomethionyl derivative data were collected to 3.3 Å resolution. All the crystals belonged to space group I2 1 3, with approximate unit-cell parameters a = b = c = 126 Å
Hydrothermal decomposition of liquid crystal in subcritical water

International Nuclear Information System (INIS)

Zhuang, Xuning; He, Wenzhi; Li, Guangming; Huang, Juwen; Lu, Shangming; Hou, Lianjiao

2014-01-01

Highlights: • Hydrothermal technology can effectively decompose the liquid crystal of 4-octoxy-4'-cyanobiphenyl. • The decomposition rate reached 97.6% under the optimized condition. • Octoxy-4'-cyanobiphenyl was mainly decomposed into simple and innocuous products. • The mechanism analysis reveals the decomposition reaction process. - Abstract: Treatment of liquid crystal has important significance for the environment protection and human health. This study proposed a hydrothermal process to decompose the liquid crystal of 4-octoxy-4′-cyanobiphenyl. Experiments were conducted with a 5.7 mL stainless tube reactor and heated by a salt-bath. Factors affecting the decomposition rate of 4-octoxy-4′-cyanobiphenyl were evaluated with HPLC. The decomposed liquid products were characterized by GC-MS. Under optimized conditions i.e., 0.2 mL H 2 O 2 supply, pH value 6, temperature 275 °C and reaction time 5 min, 97.6% of 4-octoxy-4′-cyanobiphenyl was decomposed into simple and environment-friendly products. Based on the mechanism analysis and products characterization, a possible hydrothermal decomposition pathway was proposed. The results indicate that hydrothermal technology is a promising choice for liquid crystal treatment
Magnetic, electrical and optical properties of liquid crystals

International Nuclear Information System (INIS)

Florea, S.C.

1980-01-01

This thesis lays stress on the study of thermotrop nematic liquid crystals. But the crystals whose mesomorphism is achieved by an increase and decrease in temperature and the crystal category exhibiting a mesomorphism in a deep freezing phase are also studied. The results of the research carried out in the laboratory of ''active media, lasers and matter-radiation interactions'' of the Institute for Physics and Technology of Radiation Apparata as well as in the laboratories of liquid crystals and nuclear magnetic resonance of the Polytechnical Institute of Bucharest during seven years have had in view two main objectives: to elucidate and prove experimentally a new mechanism of nuclear relaxation in liquid crystals, proposed by the author; to use the current experimental techniques and methods applied in the above-mentioned laboratories to characterize and test some foreign mesomorphic media which are synthesized locally, providing a wide range of applications, such as colour television. (author)
Purification, crystallization and preliminary X-ray diffraction experiment of nattokinase from Bacillus subtilis natto.

Science.gov (United States)

Yanagisawa, Yasuhide; Chatake, Toshiyuki; Chiba-Kamoshida, Kaori; Naito, Sawa; Ohsugi, Tadanori; Sumi, Hiroyuki; Yasuda, Ichiro; Morimoto, Yukio

2010-12-01

Nattokinase is a single polypeptide chain composed of 275 amino acids (molecular weight 27,724) which displays strong fibrinolytic activity. Moreover, it can activate other fibrinolytic enzymes such as pro-urokinase and tissue plasminogen activator. In the present study, native nattokinase from Bacillus subtilis natto was purified using gel-filtration chromatography and crystallized to give needle-like crystals which could be used for X-ray diffraction experiments. The crystals belonged to space group C2, with unit-cell parameters a=74.3, b=49.9, c=56.3 Å, β=95.2°. Diffraction images were processed to a resolution of 1.74 Å with an Rmerge of 5.2% (15.3% in the highest resolution shell) and a completeness of 69.8% (30.0% in the highest resolution shell). This study reports the first X-ray diffraction analysis of nattokinase.
Crystallization and preliminary X-ray diffraction analysis of the fructofuranosidase from Xanthophyllomyces dendrorhous

International Nuclear Information System (INIS)

Polo, Aitana; Linde, Dolores; Estévez, Marta; Fernández-Lobato, María; Sanz-Aparicio, Julia

2010-01-01

The invertase from X. dendrorhous has been purified, deglycosylated and crystallized and diffraction data have been collected to 2.3 Å resolution. Xanthophyllomyces dendrorhous invertase is an extracellular enzyme that releases β-fructose from the nonreducing termini of various β-d-fructofuranoside substrates. Its ability to produce neokestose by transglycosylation makes this enzyme an interesting research target for applications in industrial biotechnology. The native enzyme, which is highly glycosylated, failed to crystallize. Therefore, it was submitted to EndoH deglycosylating treatment and crystals were grown by vapour-diffusion methods. The crystals belonged to space group P2 1 2 1 2, with unit-cell parameters a = 75.29, b = 204.93, c = 146.25 Å. Several diffraction data sets were collected using a synchrotron source. Self-rotation function and gel-filtration experiments suggested that the enzyme is a dimer with twofold symmetry

Crystallization and preliminary X-ray diffraction analysis of the fructofuranosidase from Schwanniomyces occidentalis

International Nuclear Information System (INIS)

Polo, Aitana; Álvaro-Benito, Miguel; Fernández-Lobato, María; Sanz-Aparicio, Julia

2009-01-01

The invertase from Schwanniomyces occidentalis has been expressed in Saccharomyces cerevisiae, purified and crystallized. The wild-type enzyme was also purified and crystallized and diffraction data were collected to 2.9 Å resolution. Schwanniomyces occidentalis invertase is an extracellular enzyme that releases β-fructose from the nonreducing termini of various β-d-fructofuranoside substrates. Its ability to produce 6-kestose by transglycosylation makes this enzyme an interesting research target for applications in industrial biotechnology. The enzyme has been expressed in Saccharomyces cerevisiae. Recombinant and wild-type forms, which showed different glycosylation patterns, were crystallized by vapour-diffusion methods. Although crystallization trials were conducted on both forms of the protein, crystals suitable for X-ray crystallographic analyses were only obtained from the wild-type enzyme. The crystals belonged to space group P2 1 2 1 2 1 , with unit-cell parameters a = 105.78, b = 119.49, c = 137.68 Å. A diffraction data set was collected using a synchrotron source. Self-rotation function and sedimentation-velocity experiments suggested that the enzyme was dimeric with twofold symmetry
Tunable Channel Drop Filter in a Two-Dimensional Photonic Crystal Modulated by a Nematic Liquid Crystal

Directory of Open Access Journals (Sweden)

2006-01-01

Full Text Available Photonic crystals (PCs have many potential applications because of their ability to control light-wave propagation and because PC-based waveguides may be integrated into optical circuits. We propose a novel tunable PC channel drop filter based on nematic liquid crystals and investigate its properties numerically by using the finite-difference time-domain (FDTD method. The refractive indices of liquid crystals can be actively modulated after infiltrating nematic liquid crystals into the microcavity in PC waveguides with square lattices. Then we can control light propagation in a PC waveguide. We analyze the Q -factors and resonance frequencies of a tunable PC channel drop filter by considering various indices modulation of liquid crystals. The novel component can be used as wavelength division multiplexing in photonic integrated circuits.
Synthesis of novel liquid crystal compounds and their blood compatibility as anticoagulative materials

International Nuclear Information System (INIS)

Tu Mei; Cha Zhenhang; Feng Bohua; Zhou Changren

2006-01-01

The objective of this study was to synthesize new types of cholesteric liquid crystal compounds and study the anticoagulative properties of their composite membranes. Three kinds of cholesteric liquid crystal compounds were synthesized and characterized by infrared spectroscopy, differential scanning calorimetry and optical polarizing microscope. The polysiloxane, as a substrate, was blended with three liquid crystal compounds and was then used as membranes. The anticoagulative property of different polysiloxane liquid crystal composite membranes was identified by the blood compatibility tests. Three cholesteryl liquid crystals synthesized in this work contained hydrophilic soft chains and presented iridescent texture owned by cholesteric liquid crystals in the range of their liquid crystal state temperature, but only cholesteryl acryloyl oxytetraethylene glycol carbonate was in the liquid crystal state at body temperature. When liquid crystals were blended with polysiloxane to form polysiloxane/liquid crystal composite membranes, the haemocompatibility of these membranes could be improved to some extent. The blood compatibility of composite membranes whose hydrophilic property was the best was more excellent than that of other composite membranes, fewer platelets adhered and spread, and showed little distortion on the surface of materials
Crystal optimization and preliminary diffraction data analysis of the SCAN domain of Zfp206

International Nuclear Information System (INIS)

Liang, Yu; Choo, Siew Hua; Rossbach, Michael; Baburajendran, Nithya; Palasingam, Paaventhan; Kolatkar, Prasanna R

2012-01-01

Crystals of the SCAN domain of Zfp206 are tetragonal, belonging to space group I422 with unit-cell parameters a = 67.57, c = 87.54 Å and one molecule in the asymmetric unit, and diffract to 1.85 Å resolution. Zfp206 (also named Zscan10) is a transcription factor that plays an important role in maintaining the pluripotent state of embryonic stem cells. Zfp206 is a member of the SCAN-domain family of C 2 H 2 zinc-finger transcription factors. The SCAN domain is a highly conserved motif of 84 residues which mediates the self-association of and heterodimerization between SCAN-domain family transcription factors. The SCAN domain may therefore be the key to the selective oligomerization of and may combinatorially enhance the regulatory versatility of C 2 H 2 zinc fingers. This paper describes crystallization attempts with the SCAN domain of Zfp206 (Zfp206SCAN) and optimization strategies to obtain diffraction-quality crystals. The best diffracting crystal was grown in a solution consisting of 0.3 M ammonium sulfate, 0.1 M Tris–HCl pH 8.6, 25% PEG 3350, 0.1 M ethylenediaminetetraacetic acid disodium salt dehydrate (EDTA) using the hanging-drop vapour-diffusion technique. Optimized crystals diffracted to 1.85 Å resolution and belonged to space group I422, with unit-cell parameters a = 67.57, c = 87.54 Å. A Matthews analysis indicated the presence of one Zfp206SCAN molecule per asymmetric unit
Effect of lateral methoxy substitution on mesomorphic and structural properties of ferroelectric liquid crystals

Czech Academy of Sciences Publication Activity Database

Bubnov, Alexej M.; Kašpar, Miroslav; Novotná, Vladimíra; Hamplová, Věra; Glogarová, Milada; Kapernaum, N.; Giesselmann, F.

2008-01-01

Roč. 35, č. 11 (2008), s. 1329-1337 ISSN 0267-8292 R&D Projects: GA ČR GA202/05/0431; GA AV ČR IAA100100710 Grant - others:DAAD-ASCR(XE) D11-CZ7/06-07; DAAD-ASCR(XE) D7-CZ8/08-09 Institutional research plan: CEZ:AV0Z10100520 Keywords : ferroelectric liquid crystal * chiral materials * x-ray diffraction * dielectric properties * layer shrinkage * spontaneous polarisation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.132, year: 2008
Invited review liquid crystal models of biological materials and silk spinning.

Science.gov (United States)

Rey, Alejandro D; Herrera-Valencia, Edtson E

2012-06-01

A review of thermodynamic, materials science, and rheological liquid crystal models is presented and applied to a wide range of biological liquid crystals, including helicoidal plywoods, biopolymer solutions, and in vivo liquid crystals. The distinguishing characteristics of liquid crystals (self-assembly, packing, defects, functionalities, processability) are discussed in relation to biological materials and the strong correspondence between different synthetic and biological materials is established. Biological polymer processing based on liquid crystalline precursors includes viscoelastic flow to form and shape fibers. Viscoelastic models for nematic and chiral nematics are reviewed and discussed in terms of key parameters that facilitate understanding and quantitative information from optical textures and rheometers. It is shown that viscoelastic modeling the silk spinning process using liquid crystal theories sheds light on textural transitions in the duct of spiders and silk worms as well as on tactoidal drops and interfacial structures. The range and consistency of the predictions demonstrates that the use of mesoscopic liquid crystal models is another tool to develop the science and biomimetic applications of mesogenic biological soft matter. Copyright © 2011 Wiley Periodicals, Inc.
Stability of Disclinations in Nematic Liquid Crystals

International Nuclear Information System (INIS)

Wang Yusheng; Yang Guohong; Tian Lijun; Duan Yishi

2006-01-01

In the light of φ-mapping method and topological current theory, the stability of disclinations around a spherical particle in nematic liquid crystals is studied. We consider two different defect structures around a spherical particle: disclination ring and point defect at the north or south pole of the particle. We calculate the free energy of these different defects in the elastic theory. It is pointed out that the total Frank free energy density can be divided into two parts. One is the distorted energy density of director field around the disclinations. The other is the free energy density of disclinations themselves, which is shown to be concentrated at the defect and to be topologically quantized in the unit of (k-k 24 )π/2. It is shown that in the presence of saddle-splay elasticity a dipole (radial and hyperbolic hedgehog) configuration that accompanies a particle with strong homeotropic anchoring takes the structure of a small disclination ring, not a point defect.
Nanoparticles Doped, Photorefractive Liquid Crystals

National Research Council Canada - National Science Library

Kaczmarek, Malgosia

2005-01-01

...: The main objectives of this exploratory, short project will concern the study of the quality of liquid crystal cells with diluted suspensions of ferroelectric nanoparticles and their photorefractive properties...
Bismuth-ceramic nanocomposites through ball milling and liquid crystal synthetic methods

Science.gov (United States)

Dellinger, Timothy Michael

Three methods were developed for the synthesis of bismuth-ceramic nanocomposites, which are of interest due to possible use as thermoelectric materials. In the first synthetic method, high energy ball milling of bismuth metal with either MgO or SiO2 was found to produce nanostructured bismuth dispersed on a ceramic material. The morphology of the resulting bismuth depended on its wetting behavior with respect to the ceramic: the metal wet the MgO, but did not wet on the SiO2. Differential Scanning Calorimetry measurements on these composites revealed unusual thermal stability, with nanostructure retained after multiple cycles of heating and cooling through the metal's melting point. The second synthesis methodology was based on the use of lyotropic liquid crystals. These mixtures of water and amphiphilic molecules self-assemble to form periodic structures with nanometer-scale hydrophilic and hydrophobic domains. A novel shear mixing methodology was developed for bringing together reactants which were added to the liquid crystals as dissolved salts. The liquid crystals served to mediate synthesis by acting as nanoreactors to confine chemical reactions within the nanoscale domains of the mesophase, and resulted in the production of nanoparticles. By synthesizing lead sulfide (PbS) and bismuth (Bi) particles as proof-of-concept, it was shown that nanoparticle size could be controlled by controlling the dimensionality of the nanoreactors through control of the liquid crystalline phase. Particle size was shown to decrease upon going from three-dimensionally percolating nanoreactors, to two dimensional sheet-like nanoreactors, to one dimensional rod-like nanoreactors. Additionally, particle size could be controlled by varying the precursor salt concentration. Since the nanoparticles did not agglomerate in the liquid crystal immediately after synthesis, bismuth-ceramic nanocomposites could be prepared by synthesizing Bi nanoparticles and mixing in SiO2 particles which
Induced Magnetic Anisotropy in Liquid Crystals Doped with Resonant Semiconductor Nanoparticles

Directory of Open Access Journals (Sweden)

Vicente Marzal

2016-01-01

Full Text Available Currently, there are many efforts to improve the electrooptical properties of liquid crystals by means of doping them with different types of nanoparticles. In addition, liquid crystals may be used as active media to dynamically control other interesting phenomena, such as light scattering resonances. In this sense, mixtures of resonant nanoparticles hosted in a liquid crystal could be a potential metamaterial with interesting properties. In this work, the artificial magnetism induced in a mixture of semiconductor nanoparticles surrounded by a liquid crystal is analyzed. Effective magnetic permeability of mixtures has been obtained using the Maxwell-Garnett effective medium theory. Furthermore, permeability variations with nanoparticles size and their concentration in the liquid crystal, as well as the magnetic anisotropy, have been studied.
Magnetic, electric and optic properties of liquid crystals

International Nuclear Information System (INIS)

Florea, St.C.

1980-01-01

We study the nematic liquid crystals of thermotrop type. We also studied the crystals whose mesomorphism occured both at temperature increasing and decreasing and during the supercooling phase (monotrope). Investigation results performed by us have had in view the following: clearing up and experimental support of a new mechanism of nuclear relaxation in liquid crystals, proposed by author; usage of experimental techniques and methods for to characterize and test some mesomorph media used in very important applications, such as color TV. (author)
Crystallization, X-ray diffraction analysis and SIRAS/molecular-replacenent phasing of three crystal forms of Anabaena sensory rhodopsin transducer

International Nuclear Information System (INIS)

Vogeley, Lutz; Luecke, Hartmut

2006-01-01

Crystals of Anabaena sensory rhodopsin transducer, the transducer for the cyanobacterial photosensor Anabaena sensory rhodopsin, obtained in the space groups P4, C2 and P2 1 2 1 2 1 diffract to 1.8, 2.1 and 2.0 Å, respectively. Phases for these crystal forms were obtained by SIRAS phasing using an iodide quick-soak derivative (P4) and molecular replacement (C2 and P2 1 2 1 2 1 ). Anabaena sensory rhodopsin transducer (ASRT) is a 14.7 kDa soluble signaling protein associated with the membrane-embedded light receptor Anabaena sensory rhodopsin (ASR) from Anabaena sp., a freshwater cyanobacterium. Crystals of ASRT were obtained in three different space groups, P4, C2 and P2 1 2 1 2 1 , which diffract to 1.8, 2.1 and 2.0 Å, respectively. Phases for one of these crystal forms (P4) were obtained by SIRAS phasing using an iodide quick-soak derivative and a partial model was built. Phases for the remaining crystal forms were obtained by molecular replacement using the partial model from the P4 crystal form
Liquid crystals for organic thin-film transistors

Science.gov (United States)

Iino, Hiroaki; Usui, Takayuki; Hanna, Jun-Ichi

2015-04-01

Crystalline thin films of organic semiconductors are a good candidate for field effect transistor (FET) materials in printed electronics. However, there are currently two main problems, which are associated with inhomogeneity and poor thermal durability of these films. Here we report that liquid crystalline materials exhibiting a highly ordered liquid crystal phase of smectic E (SmE) can solve both these problems. We design a SmE liquid crystalline material, 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-10), for FETs and synthesize it. This material provides uniform and molecularly flat polycrystalline thin films reproducibly when SmE precursor thin films are crystallized, and also exhibits high durability of films up to 200 °C. In addition, the mobility of FETs is dramatically enhanced by about one order of magnitude (over 10 cm2 V-1 s-1) after thermal annealing at 120 °C in bottom-gate-bottom-contact FETs. We anticipate the use of SmE liquid crystals in solution-processed FETs may help overcome upcoming difficulties with novel technologies for printed electronics.
Cloning, recombinant production, crystallization and preliminary X-ray diffraction analysis of SDF2-like protein from Arabidopsis thaliana

International Nuclear Information System (INIS)

Radzimanowski, Jens; Ravaud, Stephanie; Schott, Andrea; Strahl, Sabine; Sinning, Irmgard

2009-01-01

Overexpression, purification, crystallization and preliminary X-ray diffraction of the stromal-cell-derived factor 2-like protein of Arabidopsis thaliana are reported. The crystals belonged to the space group P6 1 and diffracted to 1.95 Å resolution. The stromal-cell-derived factor 2-like protein of Arabidopsis thaliana (AtSDL) has been shown to be highly up-regulated in response to unfolded protein response (UPR) inducing reagents, suggesting that it plays a crucial role in the plant UPR pathway. AtSDL has been cloned, overexpressed, purified and crystallized using the vapour-diffusion method. Two crystal forms have been obtained under very similar conditions. The needle-shaped crystals did not diffract X-rays, while the other form diffracted to 1.95 Å resolution using a synchrotron-radiation source and belonged to the hexagonal space group P6 1 , with unit-cell parameters a = b = 96.1, c = 69.3 Å
Ab-initio crystal structure analysis and refinement approaches of oligo p-benzamides based on electron diffraction data

DEFF Research Database (Denmark)

Gorelik, Tatiana E; van de Streek, Jacco; Kilbinger, Andreas F M

2012-01-01

Ab-initio crystal structure analysis of organic materials from electron diffraction data is presented. The data were collected using the automated electron diffraction tomography (ADT) technique. The structure solution and refinement route is first validated on the basis of the known crystal stru...
Influence of rubbing-alignment on microwave modulation induced by liquid crystal

Directory of Open Access Journals (Sweden)

Wenjiang Ye

2015-06-01

Full Text Available The microwave modulation induced by liquid crystal is decided by the liquid crystal director distribution under an external applied voltage. The rubbing-alignment of substrate has an effect on the liquid crystal director, which must result in the change of microwave phase-shift. To illustrate the influence of rubbing-alignment on the microwave phase-shift, the microwave modulation property of twisted nematic liquid crystal is researched adopting the elastic theory of liquid crystal and the finite-difference iterative method. The variations of microwave phase-shift per unit-length for different pre-tilt and pre-twist angles of liquid crystal on the substrate surface and anchoring energy strengths with the applied voltage are numerically simulated. The result indicates that with the increase of pre-tilt angle and with the decrease of anchoring energy strength the weak anchoring twisted cell with pre-twisted angle 90° relative to the strong anchoring non-twisted cell can increase the microwave phase-shift per unit-length. As a result, for achieving the maximum microwave modulation, the weak anchoring twisted cell with pre-tilt angle 5° and anchoring energy strength 1×10−5J/m2 should be selected, which provides a reliably theoretical foundation for the design of liquid crystal microwave modulator.
Characterising laser beams with liquid crystal displays

Science.gov (United States)

Dudley, Angela; Naidoo, Darryl; Forbes, Andrew

2016-02-01

We show how one can determine the various properties of light, from the modal content of laser beams to decoding the information stored in optical fields carrying orbital angular momentum, by performing a modal decomposition. Although the modal decomposition of light has been known for a long time, applied mostly to pattern recognition, we illustrate how this technique can be implemented with the use of liquid-crystal displays. We show experimentally how liquid crystal displays can be used to infer the intensity, phase, wavefront, Poynting vector, and orbital angular momentum density of unknown optical fields. This measurement technique makes use of a single spatial light modulator (liquid crystal display), a Fourier transforming lens and detector (CCD or photo-diode). Such a diagnostic tool is extremely relevant to the real-time analysis of solid-state and fibre laser systems as well as mode division multiplexing as an emerging technology in optical communication.
Polarization-independent nematic liquid crystal waveguides for optofluidic applications

NARCIS (Netherlands)

d'Alessandro, A.; Martini, L.; Gilardi, G.; Beccherelli, R.; Asquini, R.

2015-01-01

We present the fabrication and the characterization of waveguides made of a nematic liquid crystal infiltrated in poly(dimethylsiloxane) channels. They are made by means of cast and molding technique and patterned using soft photolithography. The orientation of the nematic liquid crystal molecules
Automatic control unit for A neutron diffraction crystal spectrometer

Energy Technology Data Exchange (ETDEWEB)

Adib, M.; Abbas, Y.; Mostafa, M.; Hamouda, I.

1982-01-01

An automatic transistorized unit has been designed and constructed to control the operation of the double axis crystal spectrometer installed in front of one of the horizontal channels of the ET-RR-1 reactor. The function of the automatic unit is to store the diffracted neutrons at a certain angle with respect to the direction of the incident neutron beam in a selected channel of a 1024-multichannel analyzer for a certain preadjusted time period. AT the end of this time period the unit rotates the spectrometer's arm to another angle, selects the next channel of the MCA and provides the measurement of the diffracted neutron for the same time period. Such a sequence is repeated automatically over all angles required for the neutron diffraction pattern of the sample under investigation. As a result, the stored information at the MCA provides the neutron diffraction pattern as a function of channel number, where each channel corresponds to a certain scattering angle. The stored distribution at MCA can be obtained through the analyzer read out unit. The designed automatic unit has the possibility of providing the neutron diffraction pattern using a 6-digit scaler and a printer.
Orientational order parameters of a de Vries-type ferroelectric liquid crystal obtained by polarized Raman spectroscopy and x-ray diffraction

Czech Academy of Sciences Publication Activity Database

Sanchez-Castillo, A.; Osipov, M.A.; Jagiella, S.; Nguyen, Z.H.; Kašpar, Miroslav; Hamplová, Věra; Maclennan, J.; Giesselmann, F.

2012-01-01

Roč. 85, č. 6 (2012), "061703-1"-"061703-18" ISSN 1539-3755 Institutional research plan: CEZ:AV0Z10100520 Keywords : molecular and microscopic models * theories of liquid crystal structure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.313, year: 2012

Synthesis of liquid crystals derived from nitroazobenzene: a proposed multistep synthesis applied to organic chemistry laboratory classes

International Nuclear Information System (INIS)

Cristiano, Rodrigo; Cabral, Marilia Gabriela B.; Aquino, Rafael B. de; Cristiano, Claudia M.Z.

2014-01-01

We describe a synthetic route consisting of five steps from aniline to obtain liquid crystal compounds derived from nitroazobenzene. Syntheses were performed during the second half of the semester in organic chemistry laboratory classes. Students characterized the liquid crystal phase by the standard melting point techniques, differential scanning calorimetry and polarized optical microscopy. These experiments allow undergraduate students to explore fundamentally important reactions in Organic Chemistry, as well as modern concepts in Chemistry such as self-assembly and self-organization, nanostructured materials and molecular electronics. (author)
A helical naphthopyran dopant for photoresponsive cholesteric liquid crystals

OpenAIRE

Kim, Yuna; Frigoli, Michel; Vanthuyne, Nicolas; Tamaoki, Nobuyuki

2017-01-01

The first photoresponsive cholesteric liquid crystal comprising a photoisomerizable helical naphthopyran derivative dopant and a nematic liquid crystal is reported. An unprecedented helical twisting power switching ratio of over 90% allowed us to demonstrate multi-cycle rotational motion of micro-objects by UV light irradiation.
Effects of thermo-order-mechanical coupling on band structures in liquid crystal nematic elastomer porous phononic crystals.

Science.gov (United States)

Yang, Shuai; Liu, Ying

2018-08-01

Liquid crystal nematic elastomers are one kind of smart anisotropic and viscoelastic solids simultaneously combing the properties of rubber and liquid crystals, which is thermal sensitivity. In this paper, the wave dispersion in a liquid crystal nematic elastomer porous phononic crystal subjected to an external thermal stimulus is theoretically investigated. Firstly, an energy function is proposed to determine thermo-induced deformation in NE periodic structures. Based on this function, thermo-induced band variation in liquid crystal nematic elastomer porous phononic crystals is investigated in detail. The results show that when liquid crystal elastomer changes from nematic state to isotropic state due to the variation of the temperature, the absolute band gaps at different bands are opened or closed. There exists a threshold temperature above which the absolute band gaps are opened or closed. Larger porosity benefits the opening of the absolute band gaps. The deviation of director from the structural symmetry axis is advantageous for the absolute band gap opening in nematic state whist constrains the absolute band gap opening in isotropic state. The combination effect of temperature and director orientation provides an added degree of freedom in the intelligent tuning of the absolute band gaps in phononic crystals. Copyright © 2018 Elsevier B.V. All rights reserved.
A Medipix quantum area detector allows rotation electron diffraction data collection from submicrometre three-dimensional protein crystals

International Nuclear Information System (INIS)

Nederlof, Igor; Genderen, Eric van; Li, Yao-Wang; Abrahams, Jan Pieter

2013-01-01

An ultrasensitive Medipix2 detector allowed the collection of rotation electron-diffraction data from single three-dimensional protein nanocrystals for the first time. The data could be analysed using the standard X-ray crystallography programs MOSFLM and SCALA. When protein crystals are submicrometre-sized, X-ray radiation damage precludes conventional diffraction data collection. For crystals that are of the order of 100 nm in size, at best only single-shot diffraction patterns can be collected and rotation data collection has not been possible, irrespective of the diffraction technique used. Here, it is shown that at a very low electron dose (at most 0.1 e − Å −2 ), a Medipix2 quantum area detector is sufficiently sensitive to allow the collection of a 30-frame rotation series of 200 keV electron-diffraction data from a single ∼100 nm thick protein crystal. A highly parallel 200 keV electron beam (λ = 0.025 Å) allowed observation of the curvature of the Ewald sphere at low resolution, indicating a combined mosaic spread/beam divergence of at most 0.4°. This result shows that volumes of crystal with low mosaicity can be pinpointed in electron diffraction. It is also shown that strategies and data-analysis software (MOSFLM and SCALA) from X-ray protein crystallography can be used in principle for analysing electron-diffraction data from three-dimensional nanocrystals of proteins
Self-diffusion at the melting point: From H2 and N2 to liquid metals

International Nuclear Information System (INIS)

Armstrong, B.H.

1992-01-01

A nominal lower bound to the mean free diffusion time at the melting point T m was obtained earlier which provided a factor-two type estimate for self-diffusion coefficients of the alkali halides, alkali metals, eight other metals, and Ar. The argument was based on the classical Uncertainty Principle applied to the solid crystal, whereby maximum-frequency phonons lose validity as collective excitations and degenerate into aperiodic, single-particle diffusive motion at the melting point. Because of the short time scale of this motion, the perfect-gas diffusion equation and true mass can be used to obtain the self-diffusion coefficient in the Debye approximation to the phonon spectrum. This result for the self-diffusion coefficient also yields the scale factor that determines the order of magnitude of liquid self-diffusion coefficients, which has long been an open question. The earlier theory is summarized and clarified, and the results extended to the more complex molecular liquids H 2 and N 2 . It is also demonstrated that combining Lindemann's melting law with the perfect-gas diffusion equation estimate yields a well-known empirical expression for liquid-metal self-diffusion at T m . Validity of the self-diffusion estimate over a melting temperature range from 14 to more than 1,300 K and over a wide variety of crystals provides strong confirmation for the existence of the specialized diffusive motion at the melting point, as well as confirmation of a relation between the phonon spectrum of the solid crystal and diffusive motion in the melt. 21 refs., 2 tabs
Thermo-, photo-, and mechano-responsive liquid crystal networks enable tunable photonic crystals.

Science.gov (United States)

Akamatsu, N; Hisano, K; Tatsumi, R; Aizawa, M; Barrett, C J; Shishido, A

2017-10-25

Tunable photonic crystals exhibiting optical properties that respond reversibly to external stimuli have been developed using liquid crystal networks (LCNs) and liquid crystal elastomers (LCEs). These tunable photonic crystals possess an inverse opal structure and are photo-responsive, but circumvent the usual requirement to contain dye molecules in the structure that often limit their applicability and cause optical degradation. Herein, we report tunable photonic crystal films that reversibly tune the reflection peak wavelength under thermo-, photo- and mechano-stimuli, through bilayering a stimuli-responsive LCN including azobenzene units with a colourless inverse opal film composed of non-responsive, flexible durable polymers. By mechanically deforming the azobenzene containing LCN via various stimuli, the reflection peak wavelength from the bilayered film assembly could be shifted on demand. We confirm that the reflection peak shift occurs due to the deformation of the stimuli-responsive layer propagating towards and into the inverse opal layer to change its shape in response, and this shift behaviour is repeatable without optical degradation.
Molecular dynamics of liquid crystals

Science.gov (United States)

Sarman, Sten

1997-02-01

We derive Green-Kubo relations for the viscosities of a nematic liquid crystal. The derivation is based on the application of a Gaussian constraint algorithm that makes the director angular velocity of a liquid crystal a constant of motion. Setting this velocity equal to zero means that a director-based coordinate system becomes an inertial frame and that the constraint torques do not do any work on the system. The system consequently remains in equilibrium. However, one generates a different equilibrium ensemble. The great advantage of this ensemble is that the Green-Kubo relations for the viscosities become linear combinations of time correlation function integrals, whereas they are complicated rational functions in the conventional canonical ensemble. This facilitates the numerical evaluation of the viscosities by molecular dynamics simulations.
Nanoparticle guests in lyotropic liquid crystals

Science.gov (United States)

Dölle, Sarah; Park, Ji Hyun; Schymura, Stefan; Jo, Hyeran; Scalia, Giusy; Lagerwall, Jan P. F.

In this chapter we discuss the benefits, peculiarities and main challenges related to nanoparticle templating in lyotropic liquid crystals. We first give a brief bird's-eye view of the field, discussing different nanoparticles as well as different lyotropic hosts that have been explored, but then quickly focus on the dispersion of carbon nanotubes in surfactant-based lyotropic nematic phases. We discuss in some detail how the transfer of orientational order from liquid crystal host to nanoparticle guest can be verified and which degree of ordering can be expected, as well as the importance of choosing the right surfactant and its concentration for the stability of the nanoparticle suspension. We introduce a method for dispersing nanoparticles with an absolute minimum of stabilizing surfactant, based on dispersion below the Krafft temperature, and we discuss the peculiar phenomenon of filament formation in lyotropic nematic phases with a sufficient concentration of well-dispersed carbon nanotubes. Finally, we describe how the total surfactant concentration in micellar nematics can be greatly reduced by combining cat- and anionic surfactants, and we discuss how nanotubes can help in inducing the liquid crystal phase close to the isotropic-nematic boundary.
The purification, crystallization and preliminary X-ray diffraction analysis of dihydrodipicolinate synthase from Clostridium botulinum

International Nuclear Information System (INIS)

Dobson, Renwick C. J.; Atkinson, Sarah C.; Gorman, Michael A.; Newman, Janet M.; Parker, Michael W.; Perugini, Matthew A.

2008-01-01

Dihydrodipicolinate synthase (DHDPS), an enzyme in the lysine-biosynthetic pathway, is a promising target for antibiotic development against pathogenic bacteria. Here, the expression, purification, crystallization and preliminary diffraction analysis of DHDPS from C. botulinum are reported. In recent years, dihydrodipicolinate synthase (DHDPS; EC 4.2.1.52) has received considerable attention from both mechanistic and structural viewpoints. This enzyme, which is part of the diaminopimelate pathway leading to lysine, couples (S)-aspartate-β-semialdehyde with pyruvate via a Schiff base to a conserved active-site lysine. In this paper, the expression, purification, crystallization and preliminary X-ray diffraction analysis of DHDPS from Clostridium botulinum, an important bacterial pathogen, are presented. The enzyme was crystallized in a number of forms, predominantly using PEG precipitants, with the best crystal diffracting to beyond 1.9 Å resolution and displaying P4 2 2 1 2 symmetry. The unit-cell parameters were a = b = 92.9, c = 60.4 Å. The crystal volume per protein weight (V M ) was 2.07 Å 3 Da −1 , with an estimated solvent content of 41%. The structure of the enzyme will help guide the design of novel therapeutics against the C. botulinum pathogen
Crystallization and diffraction analysis of the serpin IRS-2 from the hard tick Ixodes ricinus

International Nuclear Information System (INIS)

Kovářová, Zuzana; Chmelař, Jindřich; Šanda, Miloslav; Brynda, Jiří; Mareš, Michael; Řezáčová, Pavlína

2010-01-01

Cleavage of the serpin IRS-2 from the hard tick I. ricinus by contaminating proteolytic activity mimicked the specific processing of the serpin by its target protease and resulted in a more stable form of the serpin which produced crystals that diffracted to 1.8 Å resolution. IRS-2 from the hard tick Ixodes ricinus belongs to the serpin family of protease inhibitors. It is produced in the salivary glands of the tick and its anti-inflammatory activity suggests that it plays a role in parasite–host interaction. Recombinant IRS-2 prepared by heterologous expression in a bacterial system was crystallized using the hanging-drop vapour-diffusion method. The crystals belonged to the primitive tetragonal space group P4 3 and diffracted to 1.8 Å resolution. Mass-spectrometric and electrophoretic analyses revealed that IRS-2 was cleaved by contaminating proteases during crystallization. This processing of IRS-2 mimicked the specific cleavage of the serpin by its target protease and resulted in a more stable form (the so-called relaxed conformation), which produced well diffracting crystals. Activity profiling with specific substrates and inhibitors demonstrated traces of serine and cysteine proteases in the protein stock solution
Ophthalmic compensation of visual ametropia based on a programmable diffractive lens

Science.gov (United States)

Millán, Maria S.; Pérez-Cabré, Elisabet; Romero, Lenny A.; Ramírez, Natalia

2013-11-01

Pixelated liquid crystal displays have been widely used as spatial light modulators to implement programmable diffractive optical elements (DOEs), particularly diffractive lenses. Many different applications of such components have been developed in information optics and optical processors that take advantage of their properties of great flexibility, easy and fast refreshment, and multiplexing capability in comparison with equivalent conventional refractive lenses. In this paper, we explore the application of programmable diffractive lenses displayed on the pixelated screen of a liquid crystal on silicon spatial light modulator (LCoS-SLM) to ophthalmic optics. In particular, we consider the use of programmable diffractive lenses for the visual compensation of some refractive errors (myopia, hyperopia). The theoretical principles of compensation are described and sketched using geometrical optics and paraxial ray tracing. A series of experiments with artificial eye in optical bench are conducted to analyze the compensation accuracy in terms of optical power and to compare the results with those obtained by means of conventional ophthalmic lenses. Practical considerations oriented to feasible applications are provided.
Distributed hydrophone array based on liquid crystal cell

Science.gov (United States)

Brodzeli, Zourab; Ladouceur, Francois; Silvestri, Leonardo; Michie, Andrew; Chigrinov, Vladimir; Guo, Grace Qi; Pozhidaev, Eugene P.; Kiselev, Alexei D.

2012-02-01

We describe a fibre optic hydrophone array system that could be used for underwater acoustic surveillance applications e.g. military, counter terrorist and customs authorities in protecting ports and harbors, offshore production facilities or coastal approaches as well as various marine applications. In this paper we propose a new approach to underwater sonar systems using voltage-controlled Liquid Crystals (LC) and simple multiplexing method. The proposed method permits measurements of sound under water at multiple points along an optical fibre using low cost components (LC cells), standard single mode fibre, without complex interferometric measurement techniques, electronics or demodulation software.
High Resolution Displays Using NCAP Liquid Crystals

Science.gov (United States)

Macknick, A. Brian; Jones, Phil; White, Larry

1989-07-01

Nematic curvilinear aligned phase (NCAP) liquid crystals have been found useful for high information content video displays. NCAP materials are liquid crystals which have been encapsulated in a polymer matrix and which have a light transmission which is variable with applied electric fields. Because NCAP materials do not require polarizers, their on-state transmission is substantially better than twisted nematic cells. All dimensional tolerances are locked in during the encapsulation process and hence there are no critical sealing or spacing issues. By controlling the polymer/liquid crystal morphology, switching speeds of NCAP materials have been significantly improved over twisted nematic systems. Recent work has combined active matrix addressing with NCAP materials. Active matrices, such as thin film transistors, have given displays of high resolution. The paper will discuss the advantages of NCAP materials specifically designed for operation at video rates on transistor arrays; applications for both backlit and projection displays will be discussed.
Hard X-ray diffraction enhanced imaging only using two crystals

Institute of Scientific and Technical Information of China (English)

LI Gang; WANG Nan; WU Ziyu

2004-01-01

Different configurations for the monochromator crystals and the analyzer crystals have been used in hard X-ray diffraction enhanced imaging (DEI) methods to overcome the complex task to adjust each of them to the ideal position. Here we present a very compact DEI configuration, and preliminary results of experiments performed at the Beijing Synchrotron Radiation Facility (BSRF) using only two crystals: the first one acting as monochromator and the second one as analyzer in the Bragg geometry. Refraction contrast images characterized by high contrast and spatial resolution are obtained and compared with absorption images. Differences among these images will be outlined and discussed emphasizing the potential capabilities of this very simple layout that guarantees a high transmission efficiency.
Dynamical electron diffraction simulation for non-orthogonal crystal system by a revised real space method.

Science.gov (United States)

Lv, C L; Liu, Q B; Cai, C Y; Huang, J; Zhou, G W; Wang, Y G

2015-01-01

In the transmission electron microscopy, a revised real space (RRS) method has been confirmed to be a more accurate dynamical electron diffraction simulation method for low-energy electron diffraction than the conventional multislice method (CMS). However, the RRS method can be only used to calculate the dynamical electron diffraction of orthogonal crystal system. In this work, the expression of the RRS method for non-orthogonal crystal system is derived. By taking Na2 Ti3 O7 and Si as examples, the correctness of the derived RRS formula for non-orthogonal crystal system is confirmed by testing the coincidence of numerical results of both sides of Schrödinger equation; moreover, the difference between the RRS method and the CMS for non-orthogonal crystal system is compared at the accelerating voltage range from 40 to 10 kV. Our results show that the CMS method is almost the same as the RRS method for the accelerating voltage above 40 kV. However, when the accelerating voltage is further lowered to 20 kV or below, the CMS method introduces significant errors, not only for the higher-order Laue zone diffractions, but also for zero-order Laue zone. These indicate that the RRS method for non-orthogonal crystal system is necessary to be used for more accurate dynamical simulation when the accelerating voltage is low. Furthermore, the reason for the increase of differences between those diffraction patterns calculated by the RRS method and the CMS method with the decrease of the accelerating voltage is discussed. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.
Purification, crystallization and x-ray diffraction data analysis of oxy hemoglobin-I from the catfish-Liposarcus anisitsi (Pisces)

International Nuclear Information System (INIS)

Smarra, A.L.S.; Arni, R.K.; Azevedo Junior, W.F. de; Colombo, M.F.; Bonilla-Rodriguez, G.O.

1997-01-01

Full text. Hemoglobin remains, despite the enormous amount of research involving this molecule, as a prototype of allosteric models and new conformations. The present work describes the purification crystallization and X-ray diffraction data analysis of the first hemoglobin (LHb-I) from the four components which constitutes Lopisarcus anisitsi's hemolysate. The functional behaviour of this hemoglobin has shown that proton and chloride effects are dependent on the presence of phosphates. Under these conditions emerges an alkaline Bohr effect, whereas chloride increases Hb oxygen-affinity. The usual interpretation for those findings involves pKa changes induced by phosphate binding and Cl competition for the phosphate binding site respectively. Alternatively we hypothesize that conformational changes can account for those observations. Accordingly, we have chose to perform Hb crystallization under different conditions to check for alternative conformations induced by these anions. The LHb-I has an isoelectric point of 8.1 being purified by ion-exchange chromatography on DEAE-Sephadex using a pH gradient, subsequent de ionization on amberlite M B 1 resin, concentrated and stored in liquid nitrogen until use. The protein solution was crystallized using the Sparce - matrix method, being obtained two monocrystal forms. First form: space group C 2, and cell parameters: a=185.42 A b=63.04 A c=57.59 A, α=γ= 90 deg β=92.79 deg. Crystallographic data was collected to 2.8 A. Second form: hexagonal system, a=b=63.9 A, c=327.96 A, α=β90 deg, γ=120 deg. Crystallographic data was collected to 2.7 A. The structure determination of first form has been initiated by molecular replacement methods. (author)
Powder X-ray diffraction method for the quantification of cocrystals in the crystallization mixture.

Science.gov (United States)

Padrela, Luis; de Azevedo, Edmundo Gomes; Velaga, Sitaram P

2012-08-01

The solid state purity of cocrystals critically affects their performance. Thus, it is important to accurately quantify the purity of cocrystals in the final crystallization product. The aim of this study was to develop a powder X-ray diffraction (PXRD) quantification method for investigating the purity of cocrystals. The method developed was employed to study the formation of indomethacin-saccharin (IND-SAC) cocrystals by mechanochemical methods. Pure IND-SAC cocrystals were geometrically mixed with 1:1 w/w mixture of indomethacin/saccharin in various proportions. An accurately measured amount (550 mg) of the mixture was used for the PXRD measurements. The most intense, non-overlapping, characteristic diffraction peak of IND-SAC was used to construct the calibration curve in the range 0-100% (w/w). This calibration model was validated and used to monitor the formation of IND-SAC cocrystals by liquid-assisted grinding (LAG). The IND-SAC cocrystal calibration curve showed excellent linearity (R(2) = 0.9996) over the entire concentration range, displaying limit of detection (LOD) and limit of quantification (LOQ) values of 1.23% (w/w) and 3.74% (w/w), respectively. Validation results showed excellent correlations between actual and predicted concentrations of IND-SAC cocrystals (R(2) = 0.9981). The accuracy and reliability of the PXRD quantification method depend on the methods of sample preparation and handling. The crystallinity of the IND-SAC cocrystals was higher when larger amounts of methanol were used in the LAG method. The PXRD quantification method is suitable and reliable for verifying the purity of cocrystals in the final crystallization product.
Electrically tunable zero dispersion wavelengths in photonic crystal fibers filled with a dual frequency addressable liquid crystal

International Nuclear Information System (INIS)

Wahle, Markus; Kitzerow, Heinz-Siegfried

2015-01-01

We present a liquid crystal (LC) infiltrated photonic crystal fiber, which enables the electrical tuning of the position of zero dispersion wavelengths (ZDWs). A dual frequency addressable liquid crystal is aligned perpendicular on the inclusion walls of a photonic crystal fiber, which results in an escaped radial director field. The orientation of the LC is controlled by applying an external electric field. Due to the high index of the liquid crystal the fiber guides light by the photonic band gap effect. Multiple ZDWs exist in the visible and near infrared. The positions of the ZDWs can be either blue or red shifted depending on the frequency of the applied voltage
Recent Advances in Discotic Liquid Crystal-Assisted Nanoparticles

Directory of Open Access Journals (Sweden)

Ashwathanarayana Gowda

2018-03-01

Full Text Available This article primarily summarizes recent advancement in the field of discotic liquid crystal (DLC nanocomposites. Discotic liquid crystals are nanostructured materials, usually 2 to 6 nm size and have been recognized as organic semiconducting materials. Recently, it has been observed that the dispersion of small concentration of various functionalized zero-, one- and two-dimensional nanomaterials in the supramolecular order of mesophases of DLCs imparts negligible impact on liquid crystalline properties but enhances their thermal, supramolecular and electronic properties. Synthesis, characterization and dispersion of various nanoparticles in different discotics are presented.
Liquid crystal alignment in electro-responsive nanostructured thermosetting materials based on block copolymer dispersed liquid crystal

Energy Technology Data Exchange (ETDEWEB)

Tercjak, A; Garcia, I; Mondragon, I [Materials-Technologies Group, Departamento IngenierIa Quimica y M Ambiente, Escuela Politecnica, Universidad PaIs Vasco/Euskal Herriko Unibertsitatea, Plaza Europa 1, E-20018 Donostia-San Sebastian (Spain)], E-mail: scptesza@sc.ehu.es, E-mail: inaki.mondragon@ehu.es

2008-07-09

Novel well-defined nanostructured thermosetting systems were prepared by modification of a diglicydylether of bisphenol-A epoxy resin (DGEBA) with 10 or 15 wt% amphiphilic poly(styrene-b-ethylene oxide) block copolymer (PSEO) and 30 or 40 wt% low molecular weight liquid crystal 4'-(hexyl)-4-biphenyl-carbonitrile (HBC) using m-xylylenediamine (MXDA) as a curing agent. The competition between well-defined nanostructured materials and the ability for alignment of the liquid crystal phase in the materials obtained has been studied by atomic and electrostatic force microscopy, AFM and EFM, respectively. Based on our knowledge, this is the first time that addition of an adequate amount (10 wt%) of a block copolymer to 40 wt% HBC-(DGEBA/MXDA) leads to a well-organized nanostructured thermosetting system (between a hexagonal and worm-like ordered structure), which is also electro-responsive with high rate contrast. This behavior was confirmed using electrostatic force microscopy (EFM), by means of the response of the HBC liquid crystal phase to the voltage applied to the EFM tip. In contrast, though materials containing 15 wt% PSEO and 30 wt% HBC also form a well-defined nanostructured thermosetting system, they do not show such a high contrast between the uncharged and charged surface.

Liquid crystal alignment in electro-responsive nanostructured thermosetting materials based on block copolymer dispersed liquid crystal.

Science.gov (United States)

Tercjak, A; Garcia, I; Mondragon, I

2008-07-09

Novel well-defined nanostructured thermosetting systems were prepared by modification of a diglicydylether of bisphenol-A epoxy resin (DGEBA) with 10 or 15 wt% amphiphilic poly(styrene-b-ethylene oxide) block copolymer (PSEO) and 30 or 40 wt% low molecular weight liquid crystal 4'-(hexyl)-4-biphenyl-carbonitrile (HBC) using m-xylylenediamine (MXDA) as a curing agent. The competition between well-defined nanostructured materials and the ability for alignment of the liquid crystal phase in the materials obtained has been studied by atomic and electrostatic force microscopy, AFM and EFM, respectively. Based on our knowledge, this is the first time that addition of an adequate amount (10 wt%) of a block copolymer to 40 wt% HBC-(DGEBA/MXDA) leads to a well-organized nanostructured thermosetting system (between a hexagonal and worm-like ordered structure), which is also electro-responsive with high rate contrast. This behavior was confirmed using electrostatic force microscopy (EFM), by means of the response of the HBC liquid crystal phase to the voltage applied to the EFM tip. In contrast, though materials containing 15 wt% PSEO and 30 wt% HBC also form a well-defined nanostructured thermosetting system, they do not show such a high contrast between the uncharged and charged surface.
Liquid crystal alignment in electro-responsive nanostructured thermosetting materials based on block copolymer dispersed liquid crystal

International Nuclear Information System (INIS)

Tercjak, A; Garcia, I; Mondragon, I

2008-01-01

Novel well-defined nanostructured thermosetting systems were prepared by modification of a diglicydylether of bisphenol-A epoxy resin (DGEBA) with 10 or 15 wt% amphiphilic poly(styrene-b-ethylene oxide) block copolymer (PSEO) and 30 or 40 wt% low molecular weight liquid crystal 4'-(hexyl)-4-biphenyl-carbonitrile (HBC) using m-xylylenediamine (MXDA) as a curing agent. The competition between well-defined nanostructured materials and the ability for alignment of the liquid crystal phase in the materials obtained has been studied by atomic and electrostatic force microscopy, AFM and EFM, respectively. Based on our knowledge, this is the first time that addition of an adequate amount (10 wt%) of a block copolymer to 40 wt% HBC-(DGEBA/MXDA) leads to a well-organized nanostructured thermosetting system (between a hexagonal and worm-like ordered structure), which is also electro-responsive with high rate contrast. This behavior was confirmed using electrostatic force microscopy (EFM), by means of the response of the HBC liquid crystal phase to the voltage applied to the EFM tip. In contrast, though materials containing 15 wt% PSEO and 30 wt% HBC also form a well-defined nanostructured thermosetting system, they do not show such a high contrast between the uncharged and charged surface
Tracking Traction Force Changes of Single Cells on the Liquid Crystal Surface

Directory of Open Access Journals (Sweden)

Chin Fhong Soon

2015-01-01

Full Text Available Cell migration is a key contributor to wound repair. This study presents findings indicating that the liquid crystal based cell traction force transducer (LCTFT system can be used in conjunction with a bespoke cell traction force mapping (CTFM software to monitor cell/surface traction forces from quiescent state in real time. In this study, time-lapse photo microscopy allowed cell induced deformations in liquid crystal coated substrates to be monitored and analyzed. The results indicated that the system could be used to monitor the generation of cell/surface forces in an initially quiescent cell, as it migrated over the culture substrate, via multiple points of contact between the cell and the surface. Future application of this system is the real-time assaying of the pharmacological effects of cytokines on the mechanics of cell migration.
Single-crystal neutron diffraction study of ammonium nitrate phase III

International Nuclear Information System (INIS)

Choi, C.S.; Prask, H.J.

1982-01-01

The crystal structure of ammonium nitrate phase III has been studied at room temperature by neutron diffraction using a single crystal containing 5% KNO 3 in solid-solution form. The space group is Pnma, with a = 7.6772 (4), b = 5.8208 (4), c = 7.1396 (5) A, Z = 4. The final residual after full-matrix least-squares refinement was R = 0.042 for 348 observed reflections. The ammonium ions are thermally disordered into two orientations, displaced by an angle of approximately 42 0 about an axis parallel to the c axis. (Auth.)
Crystallization and preliminary X-ray diffraction studies of polyketide synthase-1 (PKS-1) from Cannabis sativa

International Nuclear Information System (INIS)

Taguchi, Chiho; Taura, Futoshi; Tamada, Taro; Shoyama, Yoshinari; Shoyama, Yukihiro; Tanaka, Hiroyuki; Kuroki, Ryota; Morimoto, Satoshi

2008-01-01

Polyketide synthase-1 from C. sativa has been crystallized. The crystal diffracted to 1.55 Å resolution with sufficient quality for further structure determination. Polyketide synthase-1 (PKS-1) is a novel type III polyketide synthase that catalyzes the biosynthesis of hexanoyl triacetic acid lactone in Cannabis sativa (Mexican strain). PKS-1 was overproduced in Escherichia coli, purified and finally crystallized in two different space groups. The crystal obtained in 0.1 M HEPES buffer pH 7.5 containing 0.2 M calcium acetate and 20%(w/v) polyethylene glycol 3350 diffracted to 1.65 Å resolution and belonged to space group P1, with unit-cell parameters a = 54.3, b = 59.3, c = 62.6 Å, α = 69, β = 81, γ = 80°. Another crystal obtained in 0.1 M HEPES buffer pH 7.5 containing 0.2 M sodium chloride and 20%(w/v) polyethylene glycol 3350 diffracted to 1.55 Å resolution and belonged to space group P2 1 2 1 2 1 , with unit-cell parameters a = 54.3, b = 110, c = 130 Å. These data will enable us to determine the crystal structure of PKS-1
Crystallization and preliminary X-ray diffraction studies of polyketide synthase-1 (PKS-1) from Cannabis sativa

Energy Technology Data Exchange (ETDEWEB)

Taguchi, Chiho [Faculty of Pharmaceutical Sciences, Kyushu University (Japan); Quantum Beam Science Directorate, Japan Atomic Energy Agency (Japan); Taura, Futoshi [Faculty of Pharmaceutical Sciences, Kyushu University (Japan); Tamada, Taro; Shoyama, Yoshinari [Quantum Beam Science Directorate, Japan Atomic Energy Agency (Japan); Shoyama, Yukihiro; Tanaka, Hiroyuki [Faculty of Pharmaceutical Sciences, Kyushu University (Japan); Kuroki, Ryota [Quantum Beam Science Directorate, Japan Atomic Energy Agency (Japan); Morimoto, Satoshi [Faculty of Pharmaceutical Sciences, Kyushu University (Japan)

2008-03-01

Polyketide synthase-1 from C. sativa has been crystallized. The crystal diffracted to 1.55 Å resolution with sufficient quality for further structure determination. Polyketide synthase-1 (PKS-1) is a novel type III polyketide synthase that catalyzes the biosynthesis of hexanoyl triacetic acid lactone in Cannabis sativa (Mexican strain). PKS-1 was overproduced in Escherichia coli, purified and finally crystallized in two different space groups. The crystal obtained in 0.1 M HEPES buffer pH 7.5 containing 0.2 M calcium acetate and 20%(w/v) polyethylene glycol 3350 diffracted to 1.65 Å resolution and belonged to space group P1, with unit-cell parameters a = 54.3, b = 59.3, c = 62.6 Å, α = 69, β = 81, γ = 80°. Another crystal obtained in 0.1 M HEPES buffer pH 7.5 containing 0.2 M sodium chloride and 20%(w/v) polyethylene glycol 3350 diffracted to 1.55 Å resolution and belonged to space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 54.3, b = 110, c = 130 Å. These data will enable us to determine the crystal structure of PKS-1.
Investigation of the liquid crystal alignment layer: effect on electrical properties

International Nuclear Information System (INIS)

Abderrahmen, Asma; Romdhane, Fayda Fekih; Gharbi, Abdelhafidh; Ouada, Hafedh Ben

2008-01-01

We investigate the electrical behavior of a symmetric liquid crystal (LC) cell: elecrode-silane-LC-silane-electrode. The silane (chlorodimethyloctadecyl-silane) layer induces a homeotropic orientation of the nematic liquid crystal (NLC) molecules. The wettability technique is used to detect the change of the surface energy of the electrode upon cleaning and silane layer deposition. We report on the dynamic impedance measurements of the nematic liquid crystal cell. It is found that the silane alignment layer has a blocking effect on the liquid crystal (LC) cell. We also study the relaxation behavior of the cell which is later assimilated as an electrical equivalent circuit
Investigation of the liquid crystal alignment layer: effect on electrical properties

Energy Technology Data Exchange (ETDEWEB)

Abderrahmen, Asma; Romdhane, Fayda Fekih; Gharbi, Abdelhafidh [Laboratoire de la matiere molle, Faculte des sciences, Tunis (Tunisia); Ouada, Hafedh Ben [Laboratoire de physique et chimie des interfaces, Faculte des sciences, 5000 Monastir (Tunisia)], E-mail: asma_abderrahmen@yahoo.fr

2008-04-01

We investigate the electrical behavior of a symmetric liquid crystal (LC) cell: elecrode-silane-LC-silane-electrode. The silane (chlorodimethyloctadecyl-silane) layer induces a homeotropic orientation of the nematic liquid crystal (NLC) molecules. The wettability technique is used to detect the change of the surface energy of the electrode upon cleaning and silane layer deposition. We report on the dynamic impedance measurements of the nematic liquid crystal cell. It is found that the silane alignment layer has a blocking effect on the liquid crystal (LC) cell. We also study the relaxation behavior of the cell which is later assimilated as an electrical equivalent circuit.
Anomalous transparency in photonic crystals and its application to point-by-point grating inscription in photonic crystal fibers.

Science.gov (United States)

Baghdasaryan, Tigran; Geernaert, Thomas; Chah, Karima; Caucheteur, Christophe; Schuster, Kay; Kobelke, Jens; Thienpont, Hugo; Berghmans, Francis

2018-04-03

It is common belief that photonic crystals behave similarly to isotropic and transparent media only when their feature sizes are much smaller than the wavelength of light. Here, we counter that belief and we report on photonic crystals that are transparent for anomalously high normalized frequencies up to 0.9, where the crystal's feature sizes are comparable with the free space wavelength. Using traditional photonic band theory, we demonstrate that the isofrequency curves can be circular in the region above the first stop band for triangular lattice photonic crystals. In addition, by simulating how efficiently a tightly focused Gaussian beam propagates through the photonic crystal slab, we judge on the photonic crystal's transparency rather than on isotropy only. Using this approach, we identified a wide range of photonic crystal parameters that provide anomalous transparency. Our findings indicate the possibility to scale up the features of photonic crystals and to extend their operational wavelength range for applications including optical cloaking and graded index guiding. We applied our result in the domain of femtosecond laser micromachining, by demonstrating what we believe to be the first point-by-point grating inscribed in a multi-ring photonic crystal fiber.
Study of optical Laue diffraction

International Nuclear Information System (INIS)

Chakravarthy, Giridhar; Allam, Srinivasa Rao; Satyanarayana, S. V. M.; Sharan, Alok

2014-01-01

We present the study of the optical diffraction pattern of one and two-dimensional gratings with defects, designed using desktop pc and printed on OHP sheet using laser printer. Gratings so prepared, using novel low cost technique provides good visual aid in teaching. Diffraction pattern of the monochromatic light (632.8nm) from the grating so designed is similar to that of x-ray diffraction pattern of crystal lattice with point defects in one and two-dimensions. Here both optical and x-ray diffractions are Fraunhofer. The information about the crystalline lattice structure and the defect size can be known
Study of optical Laue diffraction

Energy Technology Data Exchange (ETDEWEB)

Chakravarthy, Giridhar, E-mail: cgiridhar84@gmail.com, E-mail: aloksharan@email.com; Allam, Srinivasa Rao, E-mail: cgiridhar84@gmail.com, E-mail: aloksharan@email.com; Satyanarayana, S. V. M., E-mail: cgiridhar84@gmail.com, E-mail: aloksharan@email.com; Sharan, Alok, E-mail: cgiridhar84@gmail.com, E-mail: aloksharan@email.com [Department of Physics, Pondicherry University, Puducherry-605014 (India)

2014-10-15

We present the study of the optical diffraction pattern of one and two-dimensional gratings with defects, designed using desktop pc and printed on OHP sheet using laser printer. Gratings so prepared, using novel low cost technique provides good visual aid in teaching. Diffraction pattern of the monochromatic light (632.8nm) from the grating so designed is similar to that of x-ray diffraction pattern of crystal lattice with point defects in one and two-dimensions. Here both optical and x-ray diffractions are Fraunhofer. The information about the crystalline lattice structure and the defect size can be known.
Slow-light enhanced optical detection in liquid-infiltrated photonic crystals

DEFF Research Database (Denmark)

Pedersen, Martin Erland Vestergaard; Rishøj, Lars Søgaard; Steffensen, Henrik

2007-01-01

Slow-light enhanced optical detection in liquid-infiltrated photonic crystals is theoretically studied. Using a scattering-matrix approach and the Wigner–Smith delay time concept, we show that optical absorbance benefits both from slow-light phenomena as well as a high filling factor of the energy...... residing in the liquid. Utilizing strongly dispersive photonic crystal structures, we numerically demonstrate how liquid-infiltrated photonic crystals facilitate enhanced light–matter interactions, by potentially up to an order of magnitude. The proposed concept provides strong opportunities for improving...
A Medipix quantum area detector allows rotation electron diffraction data collection from submicrometre three-dimensional protein crystals

Energy Technology Data Exchange (ETDEWEB)

Nederlof, Igor; Genderen, Eric van; Li, Yao-Wang; Abrahams, Jan Pieter, E-mail: abrahams@chem.leidenuniv.nl [Leiden University, Einsteinweg 55, 2333 CC Leiden (Netherlands)

2013-07-01

An ultrasensitive Medipix2 detector allowed the collection of rotation electron-diffraction data from single three-dimensional protein nanocrystals for the first time. The data could be analysed using the standard X-ray crystallography programs MOSFLM and SCALA. When protein crystals are submicrometre-sized, X-ray radiation damage precludes conventional diffraction data collection. For crystals that are of the order of 100 nm in size, at best only single-shot diffraction patterns can be collected and rotation data collection has not been possible, irrespective of the diffraction technique used. Here, it is shown that at a very low electron dose (at most 0.1 e{sup −} Å{sup −2}), a Medipix2 quantum area detector is sufficiently sensitive to allow the collection of a 30-frame rotation series of 200 keV electron-diffraction data from a single ∼100 nm thick protein crystal. A highly parallel 200 keV electron beam (λ = 0.025 Å) allowed observation of the curvature of the Ewald sphere at low resolution, indicating a combined mosaic spread/beam divergence of at most 0.4°. This result shows that volumes of crystal with low mosaicity can be pinpointed in electron diffraction. It is also shown that strategies and data-analysis software (MOSFLM and SCALA) from X-ray protein crystallography can be used in principle for analysing electron-diffraction data from three-dimensional nanocrystals of proteins.
Characterization of monoclinic crystals in tablets by pattern-fitting procedure using X-ray powder diffraction data.

Science.gov (United States)

Yamamura, Shigeo; Momose, Yasunori

2003-06-18

The purpose of this study is to characterize the monoclinic crystals in tablets by using X-ray powder diffraction data and to evaluate the deformation feature of crystals during compression. The monoclinic crystals of acetaminophen and benzoic acid were used as the samples. The observed X-ray diffraction intensities were fitted to the analytic expression, and the fitting parameters, such as the lattice parameters, the peak-width parameters, the preferred orientation parameter and peak asymmetric parameter were optimized by a non-linear least-squares procedure. The Gauss and March distribution functions were used to correct the preferred orientation of crystallites in the tablet. The March function performed better in correcting the modification of diffraction intensity by preferred orientation of crystallites, suggesting that the crystallites in the tablets had fiber texture with axial orientation. Although a broadening of diffraction peaks was observed in acetaminophen tablets with an increase of compression pressure, little broadening was observed in the benzoic tablets. These results suggest that "acetaminophen is a material consolidating by fragmentation of crystalline particles and benzoic acid is a material consolidating by plastic deformation then occurred rearrangement of molecules during compression". A pattern-fitting procedure is the superior method for characterizing the crystalline drugs of monoclinic crystals in the tablets, as well as orthorhombic isoniazid and mannitol crystals reported in the previous paper.
LCP crystallization and X-ray diffraction analysis of VcmN, a MATE transporter from Vibrio cholerae

Energy Technology Data Exchange (ETDEWEB)

Kusakizako, Tsukasa [Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Tanaka, Yoshiki [Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192 (Japan); Hipolito, Christopher J. [Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575 (Japan); Kuroda, Teruo [Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553 (Japan); Ishitani, Ryuichiro [Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Suga, Hiroaki [Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Nureki, Osamu, E-mail: nureki@bs.s.u-tokyo.ac.jp [Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan)

2016-06-22

A V. cholerae MATE transporter was crystallized using the lipidic cubic phase (LCP) method. X-ray diffraction data sets were collected from single crystals obtained in a sandwich plate and a sitting-drop plate to resolutions of 2.5 and 2.2 Å, respectively. Multidrug and toxic compound extrusion (MATE) transporters, one of the multidrug exporter families, efflux xenobiotics towards the extracellular side of the membrane. Since MATE transporters expressed in bacterial pathogens contribute to multidrug resistance, they are important therapeutic targets. Here, a MATE-transporter homologue from Vibrio cholerae, VcmN, was overexpressed in Escherichia coli, purified and crystallized in lipidic cubic phase (LCP). X-ray diffraction data were collected to 2.5 Å resolution from a single crystal obtained in a sandwich plate. The crystal belonged to space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 52.3, b = 93.7, c = 100.2 Å. As a result of further LCP crystallization trials, crystals of larger size were obtained using sitting-drop plates. X-ray diffraction data were collected to 2.2 Å resolution from a single crystal obtained in a sitting-drop plate. The crystal belonged to space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 61.9, b = 91.8, c = 100.9 Å. The present work provides valuable insights into the atomic resolution structure determination of membrane transporters.
Crystallization and preliminary X-ray diffraction analysis of a tRNASer acceptor-stem microhelix

International Nuclear Information System (INIS)

Förster, Charlotte; Krauss, Norbert; Brauer, Arnd B. E.; Szkaradkiewicz, Karol; Brode, Svenja; Hennig, Klaus; Fürste, Jens P.; Perbandt, Markus; Betzel, Christian; Erdmann, Volker A.

2006-01-01

In order to investigate tRNA identity elements, an elongator tRNA Ser acceptor-stem helix was crystallized and a data set was collected to 1.8 Å resolution aiming at a comparison with the corresponding region in suppressor tRNA Sec . In order to understand elongator tRNA Ser and suppressor tRNA Sec identity elements, the respective acceptor-stem helices have been synthesized and crystallized in order to analyse and compare their structures in detail at high resolution. The synthesis, crystallization and preliminary X-ray diffraction results for a seven-base-pair tRNA Ser acceptor-stem helix are presented here. Diffraction data were collected to 1.8 Å, applying synchrotron radiation and cryogenic cooling. The crystals belong to the monoclinic space group C2, with unit-cell parameters a = 36.14, b = 38.96, c = 30.81 Å, β = 110.69°
Secondary extinction in cylindrical and spherical crystals for X-ray and neutron diffraction

International Nuclear Information System (INIS)

Hu Huachen; Li Zhaohuan; Yang Bin; Shen Caiwan

2001-01-01

The distribution of the reflection power ratio for a neutron or x-ray diffracted from a cylindrical crystal immersed in an homogenous incident beam is obtained by the numerical solution of the transfer equations for the first time. The profile well reflects all the physical properties of the absorption and extinction behaviour in the crystals. A systematic investigation of the secondary extinction for cylindrical and spherical crystals was carried out based on these results
Molecular structure and correlations in liquid D-2-propanol through neutron diffraction

International Nuclear Information System (INIS)

Sahoo, A.; Sarkar, S.; Joarder, R.N.; Krishna, P.S.R.

2003-01-01

Like t-butanol, 2-propanol molecules are quite big with substantial amount of asymmetry in the structure and so the analysis of the neutron diffraction data is tricky. A modified method of analysis, similar to one for liquid t-butanol, enables extraction of the detailed molecular conformation and intermolecular correlations through neutron diffraction. The pre-peak in the structure function, a signature of chain molecular association together with partially identified inter-molecular correlations yield some information about the nature of possible H-bonded molecular clusters in the liquid state. (author)
Liquid Crystal Microlenses for Autostereoscopic Displays

Directory of Open Access Journals (Sweden)

José Francisco Algorri

2016-01-01

Full Text Available Three-dimensional vision has acquired great importance in the audiovisual industry in the past ten years. Despite this, the first generation of autostereoscopic displays failed to generate enough consumer excitement. Some reasons are little 3D content and performance issues. For this reason, an exponential increase in three-dimensional vision research has occurred in the last few years. In this review, a study of the historical impact of the most important technologies has been performed. This study is carried out in terms of research manuscripts per year. The results reveal that research on spatial multiplexing technique is increasing considerably and today is the most studied. For this reason, the state of the art of this technique is presented. The use of microlenses seems to be the most successful method to obtain autostereoscopic vision. When they are fabricated with liquid crystal materials, extended capabilities are produced. Among the numerous techniques for manufacturing liquid crystal microlenses, this review covers the most viable designs for its use in autostereoscopic displays. For this reason, some of the most important topologies and their relation with autostereoscopic displays are presented. Finally, the challenges in some recent applications, such as portable devices, and the future of three-dimensional displays based on liquid crystal microlenses are outlined.
Crystallization and preliminary X-ray diffraction analysis of a glutathione S-transferase from Xylella fastidiosa

International Nuclear Information System (INIS)

Garcia, Wanius; Travensolo, Regiane F.; Rodrigues, Nathalia C.; Muniz, João R. C.; Caruso, Célia S.; Lemos, Eliana G. M.; Araujo, Ana Paula U.; Carrilho, Emanuel

2008-01-01

Glutathione S-transferase from X. fastidiosa (xfGST) has been overexpressed in E. coli, purified and crystallized. Diffraction data were collected to 2.23 Å. Glutathione S-transferases (GSTs) form a group of multifunctional isoenzymes that catalyze the glutathione-dependent conjugation and reduction reactions involved in the cellular detoxification of xenobiotic and endobiotic compounds. GST from Xylella fastidiosa (xfGST) was overexpressed in Escherichia coli and purified by conventional affinity chromatography. In this study, the crystallization and preliminary X-ray analysis of xfGST is described. The purified protein was crystallized by the vapour-diffusion method, producing crystals that belonged to the triclinic space group P1. The unit-cell parameters were a = 47.73, b = 87.73, c = 90.74 Å, α = 63.45, β = 80.66, γ = 94.55°. xfGST crystals diffracted to 2.23 Å resolution on a rotating-anode X-ray source

Crystallization and preliminary X-ray diffraction analysis of a glutathione S-transferase from Xylella fastidiosa

Energy Technology Data Exchange (ETDEWEB)

Garcia, Wanius, E-mail: wanius@if.sc.usp.br [Laboratório de Biofísica Molecular ‘Sérgio Mascarenhas’, Instituto de Física de São Carlos, Universidade de São Paulo (USP), São Carlos (Brazil); Travensolo, Regiane F. [Grupo de Bioanalítica, Microfabricação e Separações, Instituto de Química de São Carlos, Universidade de São Paulo (USP), São Carlos (Brazil); Rodrigues, Nathalia C.; Muniz, João R. C. [Laboratório de Biofísica Molecular ‘Sérgio Mascarenhas’, Instituto de Física de São Carlos, Universidade de São Paulo (USP), São Carlos (Brazil); Caruso, Célia S. [Grupo de Bioanalítica, Microfabricação e Separações, Instituto de Química de São Carlos, Universidade de São Paulo (USP), São Carlos (Brazil); Lemos, Eliana G. M. [Laboratório de Bioquímica de Microrganismos e de Plantas, Departamento de Tecnologia, UNESP, Jaboticabal (Brazil); Araujo, Ana Paula U. [Laboratório de Biofísica Molecular ‘Sérgio Mascarenhas’, Instituto de Física de São Carlos, Universidade de São Paulo (USP), São Carlos (Brazil); Carrilho, Emanuel, E-mail: wanius@if.sc.usp.br [Grupo de Bioanalítica, Microfabricação e Separações, Instituto de Química de São Carlos, Universidade de São Paulo (USP), São Carlos (Brazil); Laboratório de Biofísica Molecular ‘Sérgio Mascarenhas’, Instituto de Física de São Carlos, Universidade de São Paulo (USP), São Carlos (Brazil)

2008-02-01

Glutathione S-transferase from X. fastidiosa (xfGST) has been overexpressed in E. coli, purified and crystallized. Diffraction data were collected to 2.23 Å. Glutathione S-transferases (GSTs) form a group of multifunctional isoenzymes that catalyze the glutathione-dependent conjugation and reduction reactions involved in the cellular detoxification of xenobiotic and endobiotic compounds. GST from Xylella fastidiosa (xfGST) was overexpressed in Escherichia coli and purified by conventional affinity chromatography. In this study, the crystallization and preliminary X-ray analysis of xfGST is described. The purified protein was crystallized by the vapour-diffusion method, producing crystals that belonged to the triclinic space group P1. The unit-cell parameters were a = 47.73, b = 87.73, c = 90.74 Å, α = 63.45, β = 80.66, γ = 94.55°. xfGST crystals diffracted to 2.23 Å resolution on a rotating-anode X-ray source.
Crystallization and preliminary diffraction analysis of Wzi, a member of the capsule export and assembly pathway in Escherichia coli

International Nuclear Information System (INIS)

Bushell, Simon R.; Lou, Hubing; Wallat, Gregor D.; Beis, Konstantinos; Whitfield, Chris; Naismith, James H.

2010-01-01

Wzi is a membrane protein from E. coli thought to be involved in the attachment of capsular polysaccharides to the bacterial surface. This reports describes recombinant Wzi’s purification, crystallization and the results of initial diffraction studies. External polysaccharide capsules provide a physical barrier that is employed by many species of bacteria for the purposes of host evasion and persistence. Wzi is a 53 kDa outer membrane β-barrel protein that is thought to play a role in the attachment of group 1 capsular polysaccharides to the cell surface. The purification and crystallization of an Escherichia coli homologue of Wzi is reported and diffraction data from native and selenomethionine-incorporated protein crystals are presented. Crystals of C-terminally His 6 -tagged Wzi diffracted to 2.8 Å resolution. Data processing showed that the crystals belonged to the orthorhombic space group C222, with unit-cell parameters a = 128.8, b = 152.8, c = 94.4 Å, α = β = γ = 90°. A His-tagged selenomethionine-containing variant of Wzi has also been crystallized in the same space group and diffraction data have been recorded to 3.8 Å resolution. Data processing shows that the variant crystal has similar unit-cell parameters to the native crystal
Crystallization and preliminary X-ray diffraction analysis of Nsp15 from SARS coronavirus

International Nuclear Information System (INIS)

Ricagno, Stéfano; Coutard, Bruno; Grisel, Sacha; Brémond, Nicolas; Dalle, Karen; Tocque, Fabienne; Campanacci, Valérie; Lichière, Julie; Lantez, Violaine; Debarnot, Claire; Cambillau, Christian; Canard, Bruno; Egloff, Marie-Pierre

2006-01-01

Crystals of Nsp15 from the aetiological agent of SARS have been grown at room temperature. Crystals have cubic symmetry and diffract to a maximum resolution of 2.7 Å. The non-structural protein Nsp15 from the aetiological agent of SARS (severe acute respiratory syndrome) has recently been characterized as a uridine-specific endoribonuclease. This enzyme plays an essential role in viral replication and transcription since a mutation in the related H229E human coronavirus nsp15 gene can abolish viral RNA synthesis. SARS full-length Nsp15 (346 amino acids) has been cloned and expressed in Escherichia coli with an N-terminal hexahistidine tag and has been purified to homogeneity. The protein was subsequently crystallized using PEG 8000 or 10 000 as precipitants. Small cubic crystals of the apoenzyme were obtained from 100 nl nanodrops. They belong to space group P4 1 32 or P4 3 32, with unit-cell parameters a = b = c = 166.8 Å. Diffraction data were collected to a maximum resolution of 2.7 Å
Crystallization and preliminary diffraction studies of SFC-1, a carbapenemase conferring antibiotic resistance

International Nuclear Information System (INIS)

Hong, Myoung-Ki; Lee, Jae Jin; Wu, Xing; Kim, Jin-Kwang; Jeong, Byeong Chul; Pham, Tan-Viet; Kim, Seung-Hwan; Lee, Sang Hee; Kang, Lin-Woo

2012-01-01

The SFC-1 gene from S. fonticola was cloned and SFC-1 was expressed, purified and crystallized. X-ray diffraction data were collected from an SFC-1 crystal to 1.6 Å resolution. SFC-1, a class A carbapenemase that confers antibiotic resistance, hydrolyzes the β-lactam rings of β-lactam antibiotics (carbapenems, cephalosporins, penicillins and aztreonam). SFC-1 presents an enormous challenge to infection control, particularly in the eradication of Gram-negative pathogens. As SFC-1 exhibits a remarkably broad substrate range, including β-lactams of all classes, the enzyme is a potential target for the development of antimicrobial agents against pathogens producing carbapenemases. In this study, SFC-1 was cloned, overexpressed, purified and crystallized. The SFC-1 crystal diffracted to 1.6 Å resolution and belonged to the orthorhombic space group P2 1 2 1 2 1 , with unit-cell parameters a = 65.8, b = 68.3, c = 88.8 Å. Two molecules are present in the asymmetric unit, with a corresponding V M of 1.99 Å 3 Da −1 and a solvent content of 38.1%
Crystallization and preliminary X-ray diffraction analysis of Nsp15 from SARS coronavirus

Energy Technology Data Exchange (ETDEWEB)

Ricagno, Stéfano; Coutard, Bruno; Grisel, Sacha; Brémond, Nicolas; Dalle, Karen; Tocque, Fabienne; Campanacci, Valérie; Lichière, Julie; Lantez, Violaine; Debarnot, Claire; Cambillau, Christian; Canard, Bruno; Egloff, Marie-Pierre, E-mail: marie-pierre.egloff@afmb.univ-mrs.fr [Centre National de la Recherche Scientifique and Universités d’Aix-Marseille I et II, UMR 6098, Architecture et Fonction des Macromolécules Biologiques, Ecole Supérieure d’Ingénieurs de Luminy-Case 925, 163 Avenue de Luminy, 13288 Marseille CEDEX 9 (France)

2006-04-01

Crystals of Nsp15 from the aetiological agent of SARS have been grown at room temperature. Crystals have cubic symmetry and diffract to a maximum resolution of 2.7 Å. The non-structural protein Nsp15 from the aetiological agent of SARS (severe acute respiratory syndrome) has recently been characterized as a uridine-specific endoribonuclease. This enzyme plays an essential role in viral replication and transcription since a mutation in the related H229E human coronavirus nsp15 gene can abolish viral RNA synthesis. SARS full-length Nsp15 (346 amino acids) has been cloned and expressed in Escherichia coli with an N-terminal hexahistidine tag and has been purified to homogeneity. The protein was subsequently crystallized using PEG 8000 or 10 000 as precipitants. Small cubic crystals of the apoenzyme were obtained from 100 nl nanodrops. They belong to space group P4{sub 1}32 or P4{sub 3}32, with unit-cell parameters a = b = c = 166.8 Å. Diffraction data were collected to a maximum resolution of 2.7 Å.
Crystallization and preliminary X-ray diffraction analysis of the glucuronoyl esterase catalytic domain from Hypocrea jecorina

International Nuclear Information System (INIS)

Wood, S. J.; Li, X.-L.; Cotta, M. A.; Biely, P.; Duke, N. E. C.; Schiffer, M.; Pokkuluri, P. R.

2008-01-01

The catalytic domain of the glucuronoyl esterase from H. jecorina was overexpresssed, purified and crystallized in space group P2 1 2 1 2 1 . X-ray diffraction data were collected to 1.9 Å resolution. The catalytic domain of the glucuronoyl esterase from Hypocrea jecorina (anamorph Trichoderma reesei) was overexpresssed, purified and crystallized by the sitting-drop vapor-diffusion method using 1.4 M sodium/potassium phosphate pH 6.9. The crystals belonged to space group P2 1 2 1 2 1 and X-ray diffraction data were collected to 1.9 Å resolution. This is the first enzyme with glucoronoyl esterase activity to be crystallized; its structure will be valuable in lignocellulose-degradation research
X-CHIP: an integrated platform for high-throughput protein crystallization and on-the-chip X-ray diffraction data collection

International Nuclear Information System (INIS)

Kisselman, Gera; Qiu, Wei; Romanov, Vladimir; Thompson, Christine M.; Lam, Robert; Battaile, Kevin P.; Pai, Emil F.; Chirgadze, Nickolay Y.

2011-01-01

The X-CHIP (X-ray Crystallography High-throughput Integrated Platform) is a novel microchip that has been developed to combine multiple steps of the crystallographic pipeline from crystallization to diffraction data collection on a single device to streamline the entire process. The X-CHIP (X-ray Crystallization High-throughput Integrated Platform) is a novel microchip that has been developed to combine multiple steps of the crystallographic pipeline from crystallization to diffraction data collection on a single device to streamline the entire process. The system has been designed for crystallization condition screening, visual crystal inspection, initial X-ray screening and data collection in a high-throughput fashion. X-ray diffraction data acquisition can be performed directly on-the-chip at room temperature using an in situ approach. The capabilities of the chip eliminate the necessity for manual crystal handling and cryoprotection of crystal samples, while allowing data collection from multiple crystals in the same drop. This technology would be especially beneficial for projects with large volumes of data, such as protein-complex studies and fragment-based screening. The platform employs hydrophilic and hydrophobic concentric ring surfaces on a miniature plate transparent to visible light and X-rays to create a well defined and stable microbatch crystallization environment. The results of crystallization and data-collection experiments demonstrate that high-quality well diffracting crystals can be grown and high-resolution diffraction data sets can be collected using this technology. Furthermore, the quality of a single-wavelength anomalous dispersion data set collected with the X-CHIP at room temperature was sufficient to generate interpretable electron-density maps. This technology is highly resource-efficient owing to the use of nanolitre-scale drop volumes. It does not require any modification for most in-house and synchrotron beamline systems and offers
X-CHIP: an integrated platform for high-throughput protein crystallization and on-the-chip X-ray diffraction data collection

Energy Technology Data Exchange (ETDEWEB)

Kisselman, Gera; Qiu, Wei; Romanov, Vladimir; Thompson, Christine M.; Lam, Robert [Ontario Cancer Institute, Princess Margaret Hospital, University Health Network, Toronto, Ontario M5G 2C4 (Canada); Battaile, Kevin P. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Pai, Emil F.; Chirgadze, Nickolay Y., E-mail: nchirgad@uhnresearch.ca [Ontario Cancer Institute, Princess Margaret Hospital, University Health Network, Toronto, Ontario M5G 2C4 (Canada); University of Toronto, Toronto, Ontario M5S 1A8 (Canada)

2011-06-01

The X-CHIP (X-ray Crystallography High-throughput Integrated Platform) is a novel microchip that has been developed to combine multiple steps of the crystallographic pipeline from crystallization to diffraction data collection on a single device to streamline the entire process. The X-CHIP (X-ray Crystallization High-throughput Integrated Platform) is a novel microchip that has been developed to combine multiple steps of the crystallographic pipeline from crystallization to diffraction data collection on a single device to streamline the entire process. The system has been designed for crystallization condition screening, visual crystal inspection, initial X-ray screening and data collection in a high-throughput fashion. X-ray diffraction data acquisition can be performed directly on-the-chip at room temperature using an in situ approach. The capabilities of the chip eliminate the necessity for manual crystal handling and cryoprotection of crystal samples, while allowing data collection from multiple crystals in the same drop. This technology would be especially beneficial for projects with large volumes of data, such as protein-complex studies and fragment-based screening. The platform employs hydrophilic and hydrophobic concentric ring surfaces on a miniature plate transparent to visible light and X-rays to create a well defined and stable microbatch crystallization environment. The results of crystallization and data-collection experiments demonstrate that high-quality well diffracting crystals can be grown and high-resolution diffraction data sets can be collected using this technology. Furthermore, the quality of a single-wavelength anomalous dispersion data set collected with the X-CHIP at room temperature was sufficient to generate interpretable electron-density maps. This technology is highly resource-efficient owing to the use of nanolitre-scale drop volumes. It does not require any modification for most in-house and synchrotron beamline systems and offers
Electrically and spatially controllable PDLC phase gratings for diffraction and modulation of laser beams

Energy Technology Data Exchange (ETDEWEB)

Hadjichristov, Georgi B., E-mail: georgibh@issp.bas.bg [Laboratory of Optics and Spectroscopy, Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., BG-1784 Sofia (Bulgaria); Marinov, Yordan G.; Petrov, Alexander G. [Laboratory of Biomolecular Layers, Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., BG-1784 Sofia, Bulgaria (Bulgaria)

2016-03-25

We present a study on electrically- and spatially-controllable laser beam diffraction, electrooptic (EO) phase modulation, as well as amplitude-frequency EO modulation by single-layer microscale polymer-dispersed liquid crystal (PDLC) phase gratings (PDLC SLPGs) of interest for device applications. PDLC SLPGs were produced from nematic liquid crystal (LC) E7 in photo-curable NOA65 polymer. The wedge-formed PDLC SLPGs have a continuously variable thickness (2–25 µm). They contain LC droplets of diameters twice as the layer thickness, with a linear-gradient size distribution along the wedge. By applying alternating-current (AC) electric field, the PDLC SLPGs produce efficient: (i) diffraction splitting of transmitted laser beams; (ii) spatial redistribution of diffracted light intensity; (iii) optical phase modulation; (iv) amplitude-frequency modulation, all controllable by the driven AC field and the droplet size gradient.
Crystallization and preliminary X-ray diffraction analysis of a specific VHH domain against mouse prion protein

International Nuclear Information System (INIS)

Abskharon, Romany N. N.; Soror, Sameh H.; Pardon, Els; El Hassan, Hassan; Legname, Giuseppe; Steyaert, Jan; Wohlkonig, Alexandre

2010-01-01

The crystallization of a specific nanobody against mouse PrP C and preliminary diffraction analysis of a crystal that diffracted to 1.23 Å resolution are presented. Prion disorders are infectious diseases that are characterized by the conversion of the cellular prion protein PrP C into the pathogenic isoform PrP Sc . Specific antibodies that interact with the cellular prion protein have been shown to inhibit this transition. Recombinant VHHs (variable domain of dromedary heavy-chain antibodies) or nanobodies are single-domain antibodies, making them the smallest antigen-binding fragments. A specific nanobody (Nb-PrP-01) was raised against mouse PrP C . A crystallization condition for this recombinant nanobody was identified using high-throughput screening. The crystals were optimized using streak-seeding and the hanging-drop method. The crystals belonged to the orthorhombic space group P2 1 2 1 2 1 , with unit-cell parameters a = 30.04, b = 37.15, c = 83.00 Å, and diffracted to 1.23 Å resolution using synchrotron radiation. The crystal structure of this specific nanobody against PrP C together with the known PrP C structure may help in understanding the PrP C /PrP Sc transition mechanism
Crystallization and preliminary X-ray diffraction analysis of the lytic transglycosylase MltE from Escherichia coli

International Nuclear Information System (INIS)

Artola-Recolons, Cecilia; Llarrull, Leticia I.; Lastochkin, Elena; Mobashery, Shahriar; Hermoso, Juan A.

2010-01-01

Crystals of the lytic transglycosylase MltE from E. coli were grown using the microbatch method and diffracted to a resolution of 2.1 Å. MltE from Escherichia coli (193 amino acids, 21 380 Da) is a lytic transglycosylase that initiates the first step of cell-wall recycling. This enzyme is responsible for the cleavage of the cell-wall peptidoglycan at the β-1,4-glycosidic bond between the N-acetylglucosamine and N-acetylmuramic acid units. At the end this reaction generates a disaccharide that is internalized and initiates the recycling process. To obtain insights into the biological functions of MltE, crystallization trials were performed and crystals of MltE protein that were suitable for X-ray diffraction analysis were obtained. The MltE protein of E. coli was crystallized using the hanging-drop vapour-diffusion method at 291 K. Crystals grew from a mixture consisting of 28% polyethylene glycol 4000, 0.1 M Tris pH 8.4 and 0.2 M magnesium chloride. Further optimization was performed using the microbatch technique. Single crystals were obtained that belonged to the orthorhombic space group C222 1 , with unit-cell parameters a = 123.32, b = 183.93, c = 35.29 Å, and diffracted to a resolution of 2.1 Å
Effects of spin orbital coupling on atomic and electronic structures in Al2Cu and Al2Au crystal and liquid phases via ab initio molecular dynamics simulations

International Nuclear Information System (INIS)

Wang, Y.; Lu, Y.H.; Wang, X.D.; Cao, Q.P.; Zhang, D.X.; Jiang, J.Z.

2014-01-01

Highlights: • The SOC effect affects the cohesion energy of crystal phase. • The effect of SOC was reduced due to random local atomic structures in liquids. • The local geometrical structures also affect the melting points. • Both SOC effect and local atomic structures are important for melting point difference. - Abstract: The origin of different melting points between Al 2 Cu and Al 2 Au has been studied using ab initio molecular dynamics simulations. Cohesive energy, electronic structures and structure information of both crystal and liquid phases have been analyzed. It is found that spin orbital coupling (SOC) plays an important role on the cohesive energy of crystal phase, consistent with the different melting points of these two alloys. Whereas, it seems that SOC has no effect on the formation energy and structure of liquid phase. Possible mechanism of reduced SOC effect at liquid phase is proposed. Our results are helpful to understand the glass formation ability difference between Al 2 Cu and Al 2 Au
New developments in flexible cholesteric liquid crystal displays

Science.gov (United States)

Schneider, Tod; Davis, Donald J.; Franklin, Sean; Venkataraman, Nithya; McDaniel, Diaz; Nicholson, Forrest; Montbach, Erica; Khan, Asad; Doane, J. William

2007-02-01

Flexible Cholesteric liquid crystal displays have been rapidly maturing into a strong contender in the flexible display market. Encapsulation of the Cholesteric liquid crystal permits the use of flexible plastic substrates and roll-to-roll production. Recent advances include ultra-thin displays, laser-cut segmented displays of variable geometry, and smart card applications. Exciting technologies such as simultaneous laser-edge sealing and singulation enable high volume production, excellent quality control and non-traditional display geometries and formats.
Crystal structure of core streptavidin determined from multi-wavelength anomalous diffraction of synchrotron radiation

International Nuclear Information System (INIS)

Hendrickson, W.A.; Paehler, A.; Smith, J.L.; Satow, Y.; Merritt, E.A.; Phizackerley, R.P.

1989-01-01

A three-dimensional crystal structure of the biotin-binding core of streptavidin has been determined at 3.1-angstrom resolution. The structure was analyzed from diffraction data measured at three wavelengths from a single crystal of the selenobiotinyl complex with streptavidin. Streptavidin is a tetramer with subunits arrayed in D 2 symmetry. Each protomer is an 8-stranded β-barrel with simple up-down topology. Biotin molecules are bound at one end of each barrel. This study demonstrates the effectiveness of multi-wavelength anomalous diffraction (MAD) procedures for macromolecular crystallography and provides a basis for detailed study of biotin-avidin interactions
Bistable switching in dual-frequency liquid crystals

Energy Technology Data Exchange (ETDEWEB)

Palto, S. P., E-mail: palto@online.ru; Barnik, M I [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

2006-06-15

Various bistable switching modes in nematic liquid crystals with frequency inversion of the sign of dielectric anisotropy are revealed and investigated. Switching between states with different helicoidal distributions of the director field of a liquid crystal, as well as between uniform and helicoidal states, is realized by dual-frequency waveforms of a driving voltage. A distinctive feature of the dual-frequency switching is that the uniform planar distribution of the director field may correspond to a thermodynamically equilibrium state, and the chirality of an LC is not a necessary condition for switching to a helicoidal state.
Crystallization and X-ray diffraction analysis of human CLEC5A (MDL-1), a dengue virus receptor

International Nuclear Information System (INIS)

Watson, Aleksandra A.; O’Callaghan, Christopher A.

2009-01-01

Recombinant human CLEC5A was crystallized in the trigonal space group P3 1 and X-ray diffraction data were collected to 1.56 Å resolution. The human C-type lectin-like protein CLEC5A (also known as MDL-1) is expressed on the surface of myeloid cells and plays a critical role in dengue-virus-induced disease by signalling through the transmembrane adaptor protein DAP12. The C-type lectin-like domain of CLEC5A was expressed in Escherichia coli, refolded and purified. Recombinant CLEC5A crystals were grown by sitting-drop vapour diffusion using polyethylene glycol 6000 as a precipitant. After optimization, crystals were grown which diffracted to 1.56 Å using synchrotron radiation. The results presented in this paper suggest that crystals producing diffraction of this quality will be suitable for structural determination of human CLEC5A
Crystallization and preliminary X-ray diffraction analysis of the haem-binding protein HemS from Yersinia enterocolitica

International Nuclear Information System (INIS)

Schneider, Sabine; Paoli, Massimo

2005-01-01

The haem binding protein HemS from Y. enterocolitica has been crystallized in complex with its ligand. The crystals diffracted X-rays to 2.6 Å in-house. Bacteria have evolved strategies to acquire iron from their environment. Pathogenic microbes rely on specialized proteins to ‘steal’ haem from their host and use it as an iron source. HemS is the ultimate recipient of a molecular-relay system for haem uptake in Gram-negative species, functioning as the cytosolic carrier of haem. Soluble expression and high-quality diffraction crystals were obtained for HemS from Yersinia enterocolitica. Crystals belong to the orthorhombic space group I222, with unit-cell parameters a = 74.86, b = 77.45, c = 114.09 Å, and diffract X-rays to 2.6 Å spacing in-house. Determination of the structure of the haem–HemS complex will reveal the molecular basis of haem binding
Crystallization and preliminary X-ray diffraction analysis of the haem-binding protein HemS from Yersinia enterocolitica

Energy Technology Data Exchange (ETDEWEB)

Schneider, Sabine; Paoli, Massimo, E-mail: max.paoli@nottingham.ac.uk [School of Pharmacy and Centre for Biomolecular Sciences, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)

2005-08-01

The haem binding protein HemS from Y. enterocolitica has been crystallized in complex with its ligand. The crystals diffracted X-rays to 2.6 Å in-house. Bacteria have evolved strategies to acquire iron from their environment. Pathogenic microbes rely on specialized proteins to ‘steal’ haem from their host and use it as an iron source. HemS is the ultimate recipient of a molecular-relay system for haem uptake in Gram-negative species, functioning as the cytosolic carrier of haem. Soluble expression and high-quality diffraction crystals were obtained for HemS from Yersinia enterocolitica. Crystals belong to the orthorhombic space group I222, with unit-cell parameters a = 74.86, b = 77.45, c = 114.09 Å, and diffract X-rays to 2.6 Å spacing in-house. Determination of the structure of the haem–HemS complex will reveal the molecular basis of haem binding.
Passive Temperature Stabilization of Silicon Photonic Devices Using Liquid Crystals

Directory of Open Access Journals (Sweden)

Joanna Ptasinski

2014-03-01

Full Text Available In this work we explore the negative thermo-optic properties of liquid crystal claddings for passive temperature stabilization of silicon photonic integrated circuits. Photonic circuits are playing an increasing role in communications and computing, but they suffer from temperature dependent performance variation. Most existing techniques aimed at compensation of thermal effects rely on power hungry Joule heating. We show that integrating a liquid crystal cladding helps to minimize the effects of a temperature dependent drift. The advantage of liquid crystals lies in their high negative thermo-optic coefficients in addition to low absorption at the infrared wavelengths.
An automatic control unit for A neutron diffraction crystal spectrometer

International Nuclear Information System (INIS)

Adib, M.; Abbas, Y.; Mostafa, M.; Hamouda, I.

1982-01-01

An automatic transistorized unit has been designed and constructed to control the operation of the double axis crystal spectrometer installed in front of one of the horizontal channels of the ET-RR-1 reactor. The function of the automatic unit is to store the diffracted neutrons at a certain angle with respect to the direction of the incident neutron beam in a selected channel of a 1024-multichannel analyzer for a certain preadjusted time period. AT the end of this time period the unit rotates the spectrometer's arm to another angle, selects the next channel of the MCA and provides the measurement of the diffracted neutron for the same time period. Such a sequence is repeated automatically over all angles required for the neutron diffraction pattern of the sample under investigation. As a result, the stored information at the MCA provides the neutron diffraction pattern as a function of channel number, where each channel corresponds to a certain scattering angle. The stored distribution at MCA can be obtained through the analyzer read out unit. The designed automatic unit has the possibility of providing the neutron diffraction pattern using a 6-digit scaler and a printer

Neutron diffraction studies of a double-crystal ( plus n,-m) setting containing a fully asymmetric diffraction geometry (FAD) of a bent perfect crystal (BPC)

Czech Academy of Sciences Publication Activity Database

Mikula, Pavol; Vrána, Miroslav; Šaroun, Jan; Em, V.

2017-01-01

Roč. 32, Supl-1 (2017), s. 13-18 ISSN 0885-7156 R&D Projects: GA ČR GC16-08803J; GA MŠk LM2015048 Institutional support: RVO:61389005 Keywords : neutron diffraction * monochromator * bent perfect crystal Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 0.674, year: 2016
Diffuse scattering from crystals with point defects

International Nuclear Information System (INIS)

Andrushevsky, N.M.; Shchedrin, B.M.; Simonov, V.I.; Malakhova, L.F.

2002-01-01

The analytical expressions for calculating the intensities of X-ray diffuse scattering from a crystal of finite dimensions and monatomic substitutional, interstitial, or vacancy-type point defects have been derived. The method for the determination of the three-dimensional structure by experimental diffuse-scattering data from crystals with point defects having various concentrations is discussed and corresponding numerical algorithms are suggested
Crystallization and preliminary X-ray diffraction analysis of alanine racemase from Pseudomonas putida YZ-26

International Nuclear Information System (INIS)

Liu, Junlin; Feng, Lei; Shi, Yawei; Feng, Wei

2012-01-01

A recombinant alanine racemase from the Pseudomonas putida YZ-26, has been crystallized by the sitting-drop vapor-diffusion method and X-ray diffraction data were collected to 2.4 Å. A recombinant form of alanine racemase (Alr) from Pseudomonas putida YZ-26 has been crystallized by the sitting-drop vapour diffusion method. X-ray diffraction data were collected to 2.4 Å resolution. The crystals belong to the space group C222 1 , with unit-cell parameters a = 118.08, b = 141.86, c = 113.83 Å, and contain an Alr dimer in the asymmetric unit. The Matthews coefficient and the solvent content were calculated to be 2.8 Å 3 Da −1 and approximately 50%, respectively
A 7 µm mini-beam improves diffraction data from small or imperfect crystals of macromolecules

International Nuclear Information System (INIS)

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

2008-01-01

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

International Nuclear Information System (INIS)

Leaw, W.L.; Mamat, C.R.; Triwahyono, S.; Jalil, A.A.; Bidin, N.

2016-01-01

Liquid crystal physical gels were (thermally) prepared with cholesteryl stearate as a gelator in nematic liquid crystal, 4-cyano-4′-pentylbiphenyl. The electro-optical performance of liquid crystal physical gels is almost entirely dependent on the gels' inherent morphology. This study involved an empirical investigation of the relationships among all of the gelation temperature, morphology, and electro-optical properties. Besides continuous cooling at room temperature, isothermal cooling was also performed at both 18 and 0 °C, corresponding to near-solid and solid phases of 4-cyano-4′-pentylbiphenyl respectively. Nevertheless, the liquid crystal physical gel was also isothermally rapidly cooled using liquid nitrogen. Polarizing optical microscopy showed that the gel structure became thinner when isothermal cooling was carried out. These thinner gel aggregates then interconnected to form larger liquid crystal domains. Moreover, it was also revealed that the gel networks were randomized. Electron spin resonance results showed that the liquid crystal director orientation was severely randomized in the presence of gel networks. Conversely, isothermal cooling using liquid nitrogen generated a higher liquid crystal director orientation order. The 6.0 wt% cholesteryl stearate/4-cyano-4′-pentylbiphenyl physical gel that was isothermally cooled using liquid nitrogen showed the lowest response time in a twisted nematic mode optical cell. - Graphical abstract: Liquid crystal physical gel was prepared using nematic liquid crystal, 4-cyano-4′-pentylbiphenyl and cholesteryl stearate as gelator. Isothermal cooling at lower temperature produced thinner gel network and larger liquid crystal domain. - Highlights: • 5CB nematic liquid crystal was successfully gelled by cholesteryl stearate gelator. • The morphology of gel network was controlled by different cooling conditions. • Thinner gel network was formed by the rapid cooling using liquid nitrogen. • Enhanced
Effect of temperature on the morphology and electro-optical properties of liquid crystal physical gel

Energy Technology Data Exchange (ETDEWEB)

Leaw, W.L. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Mamat, C.R., E-mail: che@kimia.fs.utm.my [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Triwahyono, S. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Jalil, A.A. [Department of Chemical Engineering, Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Centre of Hydrogen Energy, Institute of Future Energy, Univerisiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia); Bidin, N. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor (Malaysia)

2016-12-01

Liquid crystal physical gels were (thermally) prepared with cholesteryl stearate as a gelator in nematic liquid crystal, 4-cyano-4′-pentylbiphenyl. The electro-optical performance of liquid crystal physical gels is almost entirely dependent on the gels' inherent morphology. This study involved an empirical investigation of the relationships among all of the gelation temperature, morphology, and electro-optical properties. Besides continuous cooling at room temperature, isothermal cooling was also performed at both 18 and 0 °C, corresponding to near-solid and solid phases of 4-cyano-4′-pentylbiphenyl respectively. Nevertheless, the liquid crystal physical gel was also isothermally rapidly cooled using liquid nitrogen. Polarizing optical microscopy showed that the gel structure became thinner when isothermal cooling was carried out. These thinner gel aggregates then interconnected to form larger liquid crystal domains. Moreover, it was also revealed that the gel networks were randomized. Electron spin resonance results showed that the liquid crystal director orientation was severely randomized in the presence of gel networks. Conversely, isothermal cooling using liquid nitrogen generated a higher liquid crystal director orientation order. The 6.0 wt% cholesteryl stearate/4-cyano-4′-pentylbiphenyl physical gel that was isothermally cooled using liquid nitrogen showed the lowest response time in a twisted nematic mode optical cell. - Graphical abstract: Liquid crystal physical gel was prepared using nematic liquid crystal, 4-cyano-4′-pentylbiphenyl and cholesteryl stearate as gelator. Isothermal cooling at lower temperature produced thinner gel network and larger liquid crystal domain. - Highlights: • 5CB nematic liquid crystal was successfully gelled by cholesteryl stearate gelator. • The morphology of gel network was controlled by different cooling conditions. • Thinner gel network was formed by the rapid cooling using liquid nitrogen. �
Diffractive-refractive optics: (+,-,-,+) X-ray crystal monochromator with harmonics separation

Czech Academy of Sciences Publication Activity Database

Hrdý, Jaromír; Mikulík, P.; Oberta, Peter

2011-01-01

Roč. 18, č. 2 (2011), s. 299-301 ISSN 0909-0495 R&D Projects: GA MPO FR-TI1/412 Institutional research plan: CEZ:AV0Z10100522 Keywords : diffractive-refractive optics * x-ray synchrotron radiation monochromator * x-ray crystal monochromator * harmonics separation Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.726, year: 2011
QbD based approach for optimization of Tenofovir disoproxil fumarate loaded liquid crystal precursor with improved permeability

Directory of Open Access Journals (Sweden)

Sharvil Patil

2017-11-01

Full Text Available BCS class III drugs suffer from a drawback of low permeability even though they have high aqueous solubility. The objective of current work was to screen the suitability of glyceryl monooleate (GMO/Pluronic F127 cubic phase liquid crystals precursors for permeation enhancement and in turn the bioavailability of tenofovir disoproxil fumarate (TDF, a BCS class III drug. Spray-drying method was used for preparation of TDF loaded liquid crystal precursors (LCP consisting of GMO/Pluronic F127 and lactose monohydrate with an ability to in situ transform into stable cubic phases upon hydration. The quality by design (QbD approach (Factorial design was used for batch optimization. Spherical TDF loaded LCP as revealed by scanning electron microscopy photographs when hydrated and analyzed by small angle X-ray scattering confirmed formation of cubic phase. Differential scanning calorimetry and X-ray diffraction studies confirmed the molecular dispersion of TDF in polymer matrix and also suggested the conversion of TDF from crystalline to amorphous form. In vitro TDF release from prepared LCP showed controlled drug release over a period of 10 h. Further ex vivo studies revealed permeation enhancing activity of prepared LCP, which was highest when tested in presence of digestive enzyme extract. Thus, formulation of stable liquid crystal powder precursor can serve as an alternative for designing oral delivery system for drugs with low permeability.
Liquid crystal television spatial light modulators

Science.gov (United States)

Liu, Hua-Kuang; Chao, Tien-Hsin

1989-01-01

The spatial light modulation characteristics and capabilities of the liquid crystal television (LCTV) spatial light modulators (SLMs) are discussed. A comparison of Radio Shack, Epson, and Citizen LCTV SLMs is made.
Determination of the solid-liquid-vapor triple point pressure of carbon

International Nuclear Information System (INIS)

Haaland, D.M.

1976-01-01

A detailed experimental study of the triple point pressure of carbon using laser heating techniques has been completed. Uncertainties and conflict in previous investigations have been addressed and substantial data presented which places the solid-liquid-vapor carbon triple point at 107 +- 2 atmospheres. This is in agreement with most investigations which have located the triple point pressure between 100 and 120 atmospheres, but is in disagreement with recent low pressure carbon experiments. The absence of any significant polymorphs of carbon other than graphite suggests that the graphite-liquid-vapor triple point has been measured. Graphite samples were melted in a pressure vessel using a 400 W Nd:YAG continuous-wave laser focused to a maximum power density of approximately 80 kW/cm 2 . Melt was confirmed by detailed microstructure analysis and x-ray diffraction of the recrystallized graphite. Experiments to determine the minimum melt pressure of carbon were completed as a function of sample size, type of inert gas, and laser power density to asure that laser power densities were sufficient to produce melt at the triple point pressure of carbon, and the pressure of carbon at the surface of the sample was identical to the measured pressure of the inert gas in the pressure vessel. High-speed color cinematography of the carbon heating revealed the presence of a laser-generated vapor or particle plume in front of the sample. The existence of this bright plume pevented the measurement of the carbon triple point temperature
Crystallization and preliminary X-ray diffraction study of recombinant ribokinase from Thermus Species 2.9

Energy Technology Data Exchange (ETDEWEB)

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

2016-11-15

Ribokinase from a thermophilic strain of Thermus species 2.9 belonging to the carbohydrate ribokinase family (EC 2.7.1.15) was isolated, purified, and crystallized. The crystallization conditions were found by the vapor-diffusion technique and were then optimized to apply the capillary counter-diffusion technique. The X-ray diffraction data set was collected from the crystals, which were grown by the counter-diffusion technique, at the SPring-8 synchrotron radiation facility to 2.87 Å resolution. The crystals belong to sp. gr. P12{sub 1}1 and have the following unit-cell parameters: a = 81.613 Å, b = 156.132 Å, c = 87.714 Å, α = γ = 90°, β = 103.819°. The X-ray diffraction data set is suitable for determining the three-dimensional structure of the protein by the molecular-replacement method.
Crystal structure of aspartame anhydrate from powder diffraction data. Structural aspects of the dehydration process of aspartame

NARCIS (Netherlands)

Guguta, C.; Meekes, H.L.M.; Gelder, R. de

2006-01-01

Aspartame has three pseudo-polymorphic forms, two hydrates and a hemi-hydrate, for which crystal structures were determined from single-crystal diffraction data. This paper presents the crystal structure of the anhydrate, which was obtained by dehydrating the hemi-hydrate. The crystal structure of
Exact solution of the Takagi-Taupin equation for dynamical X-ray Bragg diffraction by a crystal with a transition layer

International Nuclear Information System (INIS)

Chukhovskii, F.N.; Khapachev, Yu. P.

1985-01-01

The general problem of dynamical diffraction on a crystal with a transition layer is theoretically considered. It is shown that the problem of dynamical diffraction on such a crystal can be solved analytically. Special attention is paid to the dependence of the curves of diffractional reflection on the parameters of the transition layer. (author)
Crystallization and preliminary diffraction studies of CBM3b of cellobiohydrolase 9A from Clostridium thermocellum

Energy Technology Data Exchange (ETDEWEB)

Jindou, Sadanari [Department of Molecular Microbiology and Biotechnology, Tel Aviv University 69978 (Israel); Petkun, Svetlana [Department of Molecular Microbiology and Biotechnology, Tel Aviv University 69978 (Israel); The Daniella Rich Institute for Structural Biology, Tel Aviv University 69978 (Israel); Shimon, Linda [Department of Chemical Research Support, The Weizmann Institute of Science, Rehovot 76100 (Israel); Bayer, Edward A. [Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100 (Israel); Lamed, Raphael; Frolow, Felix, E-mail: mbfrolow@post.tau.ac.il [Department of Molecular Microbiology and Biotechnology, Tel Aviv University 69978 (Israel); The Daniella Rich Institute for Structural Biology, Tel Aviv University 69978 (Israel)

2007-12-01

The cloning, expression, purification and crystallization of the CBM3b module of cellobiohydrolase 9A from C. thermocellum is described. The crystals diffract to 2.68 Å. Family 3 carbohydrate-binding modules (CBM3s) are associated with the scaffoldin subunit of the multi-enzyme cellulosome complex and with the family 9 glycoside hydrolases, which are multimodular enzymes that act on plant cell-wall polysaccharides, notably cellulose. Here, the crystallization of CBM3b from cellobiohydrolase 9A is reported. The crystals are tetragonal and belong to space group P4{sub 1} or P4{sub 3}. X-ray diffraction data for CBM3b have been collected to 2.68 Å resolution on beamline ID14-4 at the ESRF.
Crystallization and preliminary X-ray diffraction analysis of the glucuronoyl esterase catalytic domain from Hypocrea jecorina

Energy Technology Data Exchange (ETDEWEB)

Wood, S. J. [Biosciences Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Li, X.-L.; Cotta, M. A. [Fermentation Biotechnology Research Unit, National Center for Agricultural Utilization Research, USDA-ARS, Peoria, Illinois 61604 (United States); Biely, P. [Institute of Chemistry, Slovak Academy of Sciences, 845 38 Bratislava (Slovakia); Duke, N. E. C.; Schiffer, M.; Pokkuluri, P. R., E-mail: rajp@anl.gov [Biosciences Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

2008-04-01

The catalytic domain of the glucuronoyl esterase from H. jecorina was overexpresssed, purified and crystallized in space group P2{sub 1}2{sub 1}2{sub 1}. X-ray diffraction data were collected to 1.9 Å resolution. The catalytic domain of the glucuronoyl esterase from Hypocrea jecorina (anamorph Trichoderma reesei) was overexpresssed, purified and crystallized by the sitting-drop vapor-diffusion method using 1.4 M sodium/potassium phosphate pH 6.9. The crystals belonged to space group P2{sub 1}2{sub 1}2{sub 1} and X-ray diffraction data were collected to 1.9 Å resolution. This is the first enzyme with glucoronoyl esterase activity to be crystallized; its structure will be valuable in lignocellulose-degradation research.
Confinement effects on strongly polar alkylcyanobiphenyl liquid crystals probed by dielectric spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Leys, Jan; Glorieux, Christ; Thoen, Jan [Laboratorium voor Akoestiek en Thermische Fysica, Departement Natuurkunde en Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200D-bus 2416, B-3001 Leuven (Belgium)], E-mail: jan.leys@fys.kuleuven.be, E-mail: jan.thoen@fys.kuleuven.be

2008-06-18

Dielectric spectroscopy has often been used to study confinement effects in alkylcyanobiphenyl liquid crystals. In this paper, we highlight some of the effects that have been discovered previously and add new data and interpretation. Aerosil nanoparticles form a hydrogen bonded random porous network. In dispersions of alkylcyanobiphenyls with aerosils, an additional slow process arises, that we ascribe to the relaxation of liquid crystal molecules in close interaction with these nanoparticles. Their relaxation is retarded by a hydrogen bond interaction between the cyano group of the liquid crystals and an aerosil surface hydroxyl group. A similar surface process is also observed in Vycor porous glass, a random rigid structure with small pores. A comparison of the temperature dependence of the relaxation times of the surface processes in decylcyanobiphenyl and isopentylcyanobiphenyl is made, both for Vycor and aerosil confinement. In decylcyanobiphenyl, the temperature dependence for the bulk and surface processes is Arrhenius (in a limited temperature range above the melting point), except in Vycor, where it is a Vogel-Fulcher-Tamman dependence (over a much broader temperature range). In bulk and confined isopentylcyanobiphenyl, the molecular processes have a Vogel-Fulcher-Tamman dependence, whereas the surface processes have an Arrhenius one. Another effect is the acceleration of the rotation around the short molecular axis in confinement, and particularly in aerosil dispersions. This is a consequence of the disorder introduced in the liquid crystalline phase. The disorder drives the relaxation time towards a more isotropic value, resulting in an acceleration for the short axis rotation.
Metastable liquid-liquid transition in a molecular model of water

Science.gov (United States)

Palmer, Jeremy C.; Martelli, Fausto; Liu, Yang; Car, Roberto; Panagiotopoulos, Athanassios Z.; Debenedetti, Pablo G.

2014-06-01

Liquid water's isothermal compressibility and isobaric heat capacity, and the magnitude of its thermal expansion coefficient, increase sharply on cooling below the equilibrium freezing point. Many experimental, theoretical and computational studies have sought to understand the molecular origin and implications of this anomalous behaviour. Of the different theoretical scenarios put forward, one posits the existence of a first-order phase transition that involves two forms of liquid water and terminates at a critical point located at deeply supercooled conditions. Some experimental evidence is consistent with this hypothesis, but no definitive proof of a liquid-liquid transition in water has been obtained to date: rapid ice crystallization has so far prevented decisive measurements on deeply supercooled water, although this challenge has been overcome recently. Computer simulations are therefore crucial for exploring water's structure and behaviour in this regime, and have shown that some water models exhibit liquid-liquid transitions and others do not. However, recent work has argued that the liquid-liquid transition has been mistakenly interpreted, and is in fact a liquid-crystal transition in all atomistic models of water. Here we show, by studying the liquid-liquid transition in the ST2 model of water with the use of six advanced sampling methods to compute the free-energy surface, that two metastable liquid phases and a stable crystal phase exist at the same deeply supercooled thermodynamic condition, and that the transition between the two liquids satisfies the thermodynamic criteria of a first-order transition. We follow the rearrangement of water's coordination shell and topological ring structure along a thermodynamically reversible path from the low-density liquid to cubic ice. We also show that the system fluctuates freely between the two liquid phases rather than crystallizing. These findings provide unambiguous evidence for a liquid-liquid transition in
Twinning processes in Cu-Al-Ni martensite single crystals investigated by neutron single crystal diffraction method

Czech Academy of Sciences Publication Activity Database

Molnar, P.; Šittner, P.; Novák, V.; Lukáš, Petr

2008-01-01

Roč. 481, Sp.Iss.SI (2008), s. 513-517 ISSN 0921-5093 R&D Projects: GA AV ČR IAA100480704 Institutional research plan: CEZ:AV0Z10480505 Keywords : Cu-Al-Ni * single crystals * neutron diffraction Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.806, year: 2008
Blazed vector grating liquid crystal cells with photocrosslinkable polymeric alignment films fabricated by one-step polarizer rotation method

Science.gov (United States)

Kawai, Kotaro; Kuzuwata, Mitsuru; Sasaki, Tomoyuki; Noda, Kohei; Kawatsuki, Nobuhiro; Ono, Hiroshi

2014-12-01

Blazed vector grating liquid crystal (LC) cells, in which the directors of low-molar-mass LCs are antisymmetrically distributed, were fabricated by one-step exposure of an empty glass cell inner-coated with a photocrosslinkable polymer LC (PCLC) to UV light. By adopting a LC cell structure, twisted nematic (TN) and homogeneous (HOMO) alignments were obtained in the blazed vector grating LC cells. Moreover, the diffraction efficiency of the blazed vector grating LC cells was greatly improved by increasing the thickness of the device in comparison with that of a blazed vector grating with a thin film structure obtained in our previous study. In addition, the diffraction efficiency and polarization states of ±1st-order diffracted beams from the resultant blazed vector grating LC cells were controlled by designing a blazed pattern in the alignment films, and these diffraction properties were well explained on the basis of Jones calculus and the elastic continuum theory of nematic LCs.
Production, purification, crystallization and preliminary X-ray diffraction studies of the nucleoside diphosphate kinase b from Leishmania major

International Nuclear Information System (INIS)

Tonoli, Celisa Caldana Costa; Vieira, Plinio Salmazo; Ward, Richard John; Arni, Raghuvir Krishnaswamy; Oliveira, Arthur Henrique Cavalcante de; Murakami, Mario Tyago

2009-01-01

Overexpression, purification, crystallization and preliminary X-ray diffraction analysis of the nucleoside diphosphate kinase b from Leishmania major are reported. The crystals belonged to the trigonal space group P3 2 21 and diffracted to 2.18 Å resolution. Nucleoside diphosphate kinases (NDKs; EC 2.7.4.6) play an essential role in the synthesis of nucleotides from intermediates in the salvage pathway in all parasitic trypanosomatids and their structural studies will be instrumental in shedding light on the biochemical machinery involved in the parasite life cycle and host–parasite interactions. In this work, NDKb from Leishmania major was overexpressed in Escherichia coli, purified to homogeneity and crystallized using the sitting-drop vapour-diffusion method. The NDK crystal diffracted to 2.2 Å resolution and belonged to the trigonal crystal system, with unit-cell parameters a = 114.2, c = 93.9 Å. Translation-function calculations yielded an unambiguous solution in the enantiomorphic space group P3 2 21

Vitrification and Crystallization of Phase-Separated Metallic Liquid

Directory of Open Access Journals (Sweden)

Yun Cheng

2017-02-01

Full Text Available The liquid–liquid phase separation (LLPS behavior of Fe50Cu50 melt from 3500 K to 300 K with different rapid quenching is investigated by molecular dynamics (MD simulation based on the embedded atom method (EAM. The liquid undergoes metastable phase separation by spinodal decomposition in the undercooled regime and subsequently solidifies into three different Fe-rich microstructures: the interconnected-type structure is kept in the glass and crystal at a higher cooling rate, while the Fe-rich droplets are found to crystalize at a lower cooling rate. During the crystallization process, only Fe-rich clusters can act as the solid nuclei. The twinning planes can be observed in the crystal and only the homogeneous atomic stacking shows mirror symmetry along the twinning boundary. Our present work provides atomic-scale understanding of LLPS melt during the cooling process.
Evanescent Properties of Optical Diffraction from 2-Dimensional Hexagonal Photonic Crystals and Their Sensor Applications.

Science.gov (United States)

Liao, Yu-Yang; Chen, Yung-Tsan; Chen, Chien-Chun; Huang, Jian-Jang

2018-04-03

The sensitivity of traditional diffraction grating sensors is limited by the spatial resolution of the measurement setup. Thus, a large space is required to improve sensor performance. Here, we demonstrate a compact hexagonal photonic crystal (PhC) optical sensor with high sensitivity. PhCs are able to diffract optical beams to various angles in azimuthal space. The critical wavelength that satisfies the phase matching or becomes evanescent was used to benchmark the refractive index of a target analyte applied on a PhC sensor. Using a glucose solution as an example, our sensor demonstrated very high sensitivity and a low limit of detection. This shows that the diffraction mechanism of hexagonal photonic crystals can be used for sensors when compact size is a concern.
Crystallization of Mitochondrial Respiratory Complex II fromChicken Heart: A Membrane-Protein Complex Diffracting to 2.0Angstrom

Energy Technology Data Exchange (ETDEWEB)

Huang, Li-shar; Borders, Toni M.; Shen, John T.; Wang, Chung-Jen; Berry, Edward A.

2004-12-17

Procedure is presented for preparation of diffraction-quality crystals of a vertebrate mitochondrial respiratory Complex II. The crystals have the potential to diffract to at least 2.0 Angstrom with optimization of post-crystal-growth treatment and cryoprotection. This should allow determination of the structure of this important and medically relevant membrane protein complex at near-atomic resolution and provide great detail of the mode of binding of substrates and inhibitors at the two substrate-binding sites.
Variational Approach in the Theory of Liquid-Crystal State

Science.gov (United States)

Gevorkyan, E. V.

2018-03-01

The variational calculus by Leonhard Euler is the basis for modern mathematics and theoretical physics. The efficiency of variational approach in statistical theory of liquid-crystal state and in general case in condensed state theory is shown. The developed approach in particular allows us to introduce correctly effective pair interactions and optimize the simple models of liquid crystals with help of realistic intermolecular potentials.
Smectic liquid crystals in anisotropic colloidal silica gels

Energy Technology Data Exchange (ETDEWEB)

Liang, Dennis [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Borthwick, Matthew A [Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Leheny, Robert L [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States)

2004-05-19

We report x-ray scattering studies of the smectic liquid crystal octylcyano-biphenol (8CB) confined by strained colloidal silica gels. The gels, comprised of aerosil particles, possess an anisotropic structure that stabilizes long-range nematic order in the liquid crystal while introducing random field effects that disrupt the smectic transition. The short-range smectic correlations that form within this environment are inconsistent with the presence of a topologically ordered state predicted for 3D random field XY systems and are quantitatively like the correlations of smectics confined by isotropic gels. Detailed analysis reveals that the quenched disorder suppresses the anisotropic scaling of the smectic correlation lengths observed in the pure liquid crystal. These results and additional measurements of the smectic-A to smectic-C transition in 4-n-pentylphenylthiol-4'-n-octyloxybenzoate (8barS5) indicate that the observed smectic behaviour is dictated by random fields coupling directly to the smectic order while fields coupling to the nematic director play a subordinate role.
Guided mode studies of smectic liquid crystals

International Nuclear Information System (INIS)

Hodder, B.

2000-03-01

Recently there has been considerable interest in the use of ferroelectric liquid crystals in low power, fast switching display devices. At present the voltage switching process in surface stabilised ferroelectric liquid crystal (SSFLC) devices is not fully understood and a convenient theory for such cells has yet to be found. It is the primary aim of this work to characterise the optic tensor configuration (director profile) in thin cells (∼ 3.5 μm) containing ferroelectric liquid crystal (FLC) material. These results form a benchmark by which continuum theories may be tested. Polarised microscopy is, perhaps, the most common optical probe of liquid crystal cells. It should be appreciated that this technique is fundamentally limited, as the results are deduced from an integrated optical response of any given cell, and cannot be used to spatially resolve details of the director profile through the cell. The guided mode techniques used in this study are the primary non-integral probe and enable detailed spatial resolution of the director profile within liquid crystal cells. Analysis of guided mode data from cells containing homeotropically aligned FLC reveals the temperature dependence of the optical biaxiality and cone angle for a 40% chiral mixture of the commercially available FLC SCE8*. From these optical biaxiality measurements the temperature dependence of the biaxial order parameter C is determined. Guided mode studies of cells containing homogeneously aligned SCE8* (the conventional alignment for SSFLC devices) reveal the 0V equilibrium director profile from which a cone and chevron model is constructed. Subsequent studies of voltage induced elastic deformations of the director profile are presented and compared with a single elastic constant continuum theory which is shown to be inadequate. Optical guided mode techniques are not directly sensitive to the smectic layer configuration but X-ray scattering is. Here, for the first time, results are presented
Liquid filling of photonic crystal fibres for grating writing

DEFF Research Database (Denmark)

Sørensen, Henrik Rokkjær; Canning, John; Lægsgaard, Jesper

2007-01-01

liquid filling of photonic crystal fibres reduces the scattering from air–glass interfaces during Bragg grating writing in many layered photonic crystal fibres. Within experimental uncertainty, the grating index modulation of a grating written in germanium-doped photonic crystal fibre with 10 rings...
Purification, crystallization and preliminary X-ray diffraction experiments on the breakage-reunion domain of the DNA gyrase from Mycobacterium tuberculosis

International Nuclear Information System (INIS)

Piton, Jérémie; Matrat, Stéphanie; Petrella, Stéphanie; Jarlier, Vincent; Aubry, Alexandra; Mayer, Claudine

2009-01-01

The breakage-reunion domain of M. tuberculosis DNA gyrase was crystallized using the hanging-drop vapour-diffusion method. One of the four crystal forms obtained belonged to space group C2 and diffraction data were collected to a resolution of 2.7 Å. Mycobacterium tuberculosis DNA gyrase, a nanomachine that is involved in the regulation of DNA topology, is the only type II topoisomerase present in this organism and hence is the sole target for fluoroquinolone action. The breakage-reunion domain of the A subunit plays an essential role in DNA binding during the catalytic cycle. Two constructs of 53 and 57 kDa (termed GA53BK and GA57BK) corresponding to this domain have been overproduced, purified and crystallized. Diffraction data were collected from four crystal forms. The resolution limits ranged from 4.6 to 2.7 Å depending on the crystal form. The best diffracting crystals belonged to space group C2, with a biological dimer in the asymmetric unit. This is the first report of the crystallization and preliminary X-ray diffraction analysis of the breakage-reunion domain of DNA gyrase from a species containing one unique type II topoisomerase
2D director calculation for liquid crystal optical phased array

International Nuclear Information System (INIS)

Xu, L; Zhang, J; Wu, L Y

2005-01-01

A practical numerical model for a liquid crystal cell is set up based on the geometrical structure of liquid crystal optical phased arrays. Model parameters include width and space of electrodes, thickness of liquid crystal layer, alignment layers and glass substrates, pre-tilted angles, dielectric constants, elastic constants and so on. According to electrostatic field theory and Frank-Oseen elastic continuum theory, 2D electric potential distribution and 2D director distribution are calculated by means of the finite difference method on non-uniform grids. The influence of cell sizes on director distribution is analyzed. The fringe field effect between electrodes is also discussed
Holographic storage of three-dimensional image and data using photopolymer and polymer dispersed liquid crystal films

International Nuclear Information System (INIS)

Gao Hong-Yue; Liu Pan; Zeng Chao; Yao Qiu-Xiang; Zheng Zhiqiang; Liu Jicheng; Zheng Huadong; Yu Ying-Jie; Zeng Zhen-Xiang; Sun Tao

2016-01-01

We present holographic storage of three-dimensional (3D) images and data in a photopolymer film without any applied electric field. Its absorption and diffraction efficiency are measured, and reflective analog hologram of real object and image of digital information are recorded in the films. The photopolymer is compared with polymer dispersed liquid crystals as holographic materials. Besides holographic diffraction efficiency of the former is little lower than that of the latter, this work demonstrates that the photopolymer is more suitable for analog hologram and big data permanent storage because of its high definition and no need of high voltage electric field. Therefore, our study proposes a potential holographic storage material to apply in large size static 3D holographic displays, including analog hologram displays, digital hologram prints, and holographic disks. (special topic)
Crystallization and preliminary X-ray diffraction analysis of the peptidylprolyl isomerase Par27 of Bordetella pertussis

International Nuclear Information System (INIS)

Wohlkönig, Alexandre; Hodak, Hélène; Clantin, Bernard; Sénéchal, Magalie; Bompard, Coralie; Jacob-Dubuisson, Françoise; Villeret, Vincent

2008-01-01

Par27 from B. pertussis, the prototype of a new group of parvulins has been crystallized in two different crystal forms. Proteins with both peptidylprolyl isomerase (PPIase) and chaperone activities play a crucial role in protein folding in the periplasm of Gram-negative bacteria. Few such proteins have been structurally characterized and to date only the crystal structure of SurA from Escherichia coli has been reported. Par27, the prototype of a new group of parvulins, has recently been identified. Par27 exhibits both chaperone and PPIase activities in vitro and is the first identified parvulin protein that forms dimers in solution. Par27 has been expressed in E. coli. The protein was purified using affinity and gel-filtration chromatographic techniques and crystallized in two different crystal forms. Form A, which belongs to space group P2 (unit-cell parameters a = 42.2, b = 142.8, c = 56.0 Å, β = 95.1°), diffracts to 2.8 Å resolution, while form B, which belongs to space group C222 (unit-cell parameters a = 54.6, b = 214.1, c = 57.8 Å), diffracts to 2.2 Å resolution. Preliminary diffraction data analysis agreed with the presence of one monomer in the asymmetric unit of the orthorhombic crystal form and two in the monoclinic form
Liquid Crystal Gel Reduces Age Spots by Promoting Skin Turnover

OpenAIRE

Mina Musashi; Ariella Coler-Reilly; Teruaki Nagasawa; Yoshiki Kubota; Satomi Kato; Yoko Yamaguchi

2014-01-01

Studies have shown that liquid crystals structurally resembling the intercellular lipids in the stratum corneum can beneficially affect the skin when applied topically by stimulating the skin’s natural regenerative functions and accelerating epidermal turnover. In the present study, the effects of applying low concentrations of a liquid crystal gel of our own creation were evaluated using epidermal thickening in mouse skin as an assay for effective stimulation of epidermal turnover. A liquid ...
Creation of tunable absolute bandgaps in a two-dimensional anisotropic photonic crystal modulated by a nematic liquid crystal

International Nuclear Information System (INIS)

Liu Chenyang

2008-01-01

Photonic crystals (PCs) have many potential applications because of their ability to control light-wave propagation. We have investigated the tunable absolute bandgap in a two-dimensional anisotropic photonic crystal structures modulated by a nematic liquid crystal. The PC structure composed of an anisotropic-dielectric cylinder in the liquid crystal medium is studied by solving Maxwell's equations using the plane wave expansion method. The photonic band structures are found to exhibit absolute bandgaps for the square and triangular lattices. Numerical simulations show that the absolute bandgaps can be continuously tuned in the square and triangular lattices consisting of anisotropic-dielectric cylinders by infiltrating nematic liquid crystals. Such a mechanism of bandgap adjustment should open up a new application for designing components in photonic integrated circuits
Thermal Conductivity and Liquid Crystal Thermometers.

Science.gov (United States)

Edge, R. D., Ed.

1993-01-01

Describes using stock liquid crystal postcards as inexpensive classroom thermometers. Also suggests using these postcards as a good visual temperature indicator for classroom demonstrations such as temperature gradients. One such activity is provided. (MVL)
Single-crystal neutron diffraction studies of hydrogen-bonded systems: Two recent examples from IPNS

Energy Technology Data Exchange (ETDEWEB)

Koetzle, Thomas F. [IPNS Division, Argonne National Laboratory, Argonne, IL 60439 (United States)], E-mail: tkoetzle@anl.gov; Piccoli, Paula M.B.; Schultz, Arthur J. [IPNS Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

2009-02-21

Beginning with work in the 1950s at the first generation of research reactors, studies of hydrogen-bonded systems have been a prime application for single-crystal neutron diffraction. The range of systems studied was extended in the 1960s and 1970s, with the advent of high flux reactor sources, and beginning around 1980 studies at pulsed neutron sources have made increasingly important contributions. Recently at the Argonne Intense Pulsed Neutron Source (IPNS), working with collaborators, we completed two studies of hydrogen-bonded systems that will serve to illustrate topics of current interest. In the first study, on andrographolide, an active diterpenoid natural product, our neutron diffraction results definitively characterize the hydrogen-bonding interactions. The second IPNS study is on tetraacetylethane (TAE), a {beta}-diketone enol system with a very short, strong intramolecular O-H...O hydrogen bond. At IPNS, we have determined the neutron crystal structure of TAE at five temperatures between 20 and 298 K to investigate changes in the structure with temperature and to probe for disorder. Despite the successes illustrated by the two examples presented here and by many other studies, at present applications of single-crystal neutron diffraction continue to be extremely flux limited and constrained by the requirement for mm-size crystals for many problems. These limitations are being addressed through the realization of powerful instruments at a new generation of pulsed neutron sources, including in the USA the TOPAZ and MaNDi single-crystal diffractometers that are under development at the Spallation Neutron Source (SNS)
Single-crystal neutron diffraction studies of hydrogen-bonded systems: Two recent examples from IPNS

Science.gov (United States)

Koetzle, Thomas F.; Piccoli, Paula M. B.; Schultz, Arthur J.

2009-02-01

Beginning with work in the 1950s at the first generation of research reactors, studies of hydrogen-bonded systems have been a prime application for single-crystal neutron diffraction. The range of systems studied was extended in the 1960s and 1970s, with the advent of high flux reactor sources, and beginning around 1980 studies at pulsed neutron sources have made increasingly important contributions. Recently at the Argonne Intense Pulsed Neutron Source (IPNS), working with collaborators, we completed two studies of hydrogen-bonded systems that will serve to illustrate topics of current interest. In the first study, on andrographolide, an active diterpenoid natural product, our neutron diffraction results definitively characterize the hydrogen-bonding interactions. The second IPNS study is on tetraacetylethane (TAE), a β-diketone enol system with a very short, strong intramolecular O-H⋯O hydrogen bond. At IPNS, we have determined the neutron crystal structure of TAE at five temperatures between 20 and 298 K to investigate changes in the structure with temperature and to probe for disorder. Despite the successes illustrated by the two examples presented here and by many other studies, at present applications of single-crystal neutron diffraction continue to be extremely flux limited and constrained by the requirement for mm-size crystals for many problems. These limitations are being addressed through the realization of powerful instruments at a new generation of pulsed neutron sources, including in the USA the TOPAZ and MaNDi single-crystal diffractometers that are under development at the Spallation Neutron Source (SNS).
Single-crystal neutron diffraction studies of hydrogen-bonded systems: Two recent examples from IPNS

International Nuclear Information System (INIS)

Koetzle, Thomas F.; Piccoli, Paula M.B.; Schultz, Arthur J.

2009-01-01

Beginning with work in the 1950s at the first generation of research reactors, studies of hydrogen-bonded systems have been a prime application for single-crystal neutron diffraction. The range of systems studied was extended in the 1960s and 1970s, with the advent of high flux reactor sources, and beginning around 1980 studies at pulsed neutron sources have made increasingly important contributions. Recently at the Argonne Intense Pulsed Neutron Source (IPNS), working with collaborators, we completed two studies of hydrogen-bonded systems that will serve to illustrate topics of current interest. In the first study, on andrographolide, an active diterpenoid natural product, our neutron diffraction results definitively characterize the hydrogen-bonding interactions. The second IPNS study is on tetraacetylethane (TAE), a β-diketone enol system with a very short, strong intramolecular O-H...O hydrogen bond. At IPNS, we have determined the neutron crystal structure of TAE at five temperatures between 20 and 298 K to investigate changes in the structure with temperature and to probe for disorder. Despite the successes illustrated by the two examples presented here and by many other studies, at present applications of single-crystal neutron diffraction continue to be extremely flux limited and constrained by the requirement for mm-size crystals for many problems. These limitations are being addressed through the realization of powerful instruments at a new generation of pulsed neutron sources, including in the USA the TOPAZ and MaNDi single-crystal diffractometers that are under development at the Spallation Neutron Source (SNS).
Determination of surface tension coefficient of liquids by diffraction of light on capillary waves

International Nuclear Information System (INIS)

Nikolić, D; Nešić, Lj

2012-01-01

This paper describes a simple technique for determining the coefficient of the surface tension of liquids, based on laser light diffraction on capillary waves. Capillary waves of given frequency are created by an exciter needle acting on the surface of liquid and represent a reflective diffraction grating, the constant of which (the wavelength of capillary waves) can be determined based on a known incidence angle of light (grazing angle). We obtain the coefficient of the surface tension of liquids by applying the dispersion relation for capillary waves and analyze the difficulties that arise when setting up and conducting the experiment in detail. (paper)
X-ray diffraction studies on merohedrally twinned Δ1-62NtNBCe1-A crystals of the sodium/bicarbonate cotransporter.

Science.gov (United States)

Gill, Harindarpal S; Dutcher, Lauren; Boron, Walter F; Patel, Samir; Guay-Woodford, Lisa M

2013-07-01

NBCe1-A membrane-embedded macromolecules that cotransport sodium and bicarbonate ions across the bilayer serve to maintain acid-base homeostasis throughout the body. Defects result in a number of renal and eye disorders, including type-II renal tubular acidosis and cataracts. Here, crystals of a human truncated mutant of the cytoplasmic N-terminal domain of NBCe1 (Δ1-62NtNBCe1-A) are reported that diffract X-rays to 2.4 Å resolution. The crystal symmetry of Δ1-62NtNBCe1-A is of space group P31 with pseudo-P3121 symmetry and it has a hemihedral twin fraction of 33.0%. The crystals may provide insight into the pathogenic processes observed in a subset of patients with truncating and point mutations in the gene encoding NBCe1.
Powder diffraction from a continuous microjet of submicrometer protein crystals.

Science.gov (United States)

Shapiro, D A; Chapman, H N; Deponte, D; Doak, R B; Fromme, P; Hembree, G; Hunter, M; Marchesini, S; Schmidt, K; Spence, J; Starodub, D; Weierstall, U

2008-11-01

Atomic-resolution structures from small proteins have recently been determined from high-quality powder diffraction patterns using a combination of stereochemical restraints and Rietveld refinement [Von Dreele (2007), J. Appl. Cryst. 40, 133-143; Margiolaki et al. (2007), J. Am. Chem. Soc. 129, 11865-11871]. While powder diffraction data have been obtained from batch samples of small crystal-suspensions, which are exposed to X-rays for long periods of time and undergo significant radiation damage, the proof-of-concept that protein powder diffraction data from nanocrystals of a membrane protein can be obtained using a continuous microjet is shown. This flow-focusing aerojet has been developed to deliver a solution of hydrated protein nanocrystals to an X-ray beam for diffraction analysis. This method requires neither the crushing of larger polycrystalline samples nor any techniques to avoid radiation damage such as cryocooling. Apparatus to record protein powder diffraction in this manner has been commissioned, and in this paper the first powder diffraction patterns from a membrane protein, photosystem I, with crystallite sizes of less than 500 nm are presented. These preliminary patterns show the lowest-order reflections, which agree quantitatively with theoretical calculations of the powder profile. The results also serve to test our aerojet injector system, with future application to femtosecond diffraction in free-electron X-ray laser schemes, and for serial crystallography using a single-file beam of aligned hydrated molecules.

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

International Nuclear Information System (INIS)

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

2004-01-01

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

OpenAIRE

Yanagisawa, Yasuhide; Chatake, Toshiyuki; Chiba-Kamoshida, Kaori; Naito, Sawa; Ohsugi, Tadanori; Sumi, Hiroyuki; Yasuda, Ichiro; Morimoto, Yukio

2010-01-01

Nattokinase, a protein found in high levels in the traditional Japanese food natto, has been reported to have high thrombolytic activity. In the present study, the crystallization of native nattokinase and the collection of X-ray diffraction date from a nattokinase crystal to a resolution of 1.74 Å are reported.
Study of Inverse Ni-based Photonic Crystal using the Microradian X-ray Diffraction

Science.gov (United States)

Vasilieva, A. V.; Grigoryeva, N. A.; Mistonov, A. A.; Sapoletova, N. A.; Napolskii, K. S.; Eliseev, A. A.; Lukashin, A. V.; Tretyakov, Yu D.; Petukhov, A. V.; Byelov, D.; Chernyshov, D.; Okorokov, A. I.; Bouwman, W. G.; Grigoriev, S. V.

2010-10-01

Inverse photonic nickel-based crystal films formed by electrocrystallization of metal inside the voids of polymer artificial opal have been studied using the microradian X-ray diffraction. Analysis of the diffraction images agrees with an face-centred cubic (FCC) structure with the lattice constant a0 = 650 ± 10 nm and indicates two types of stacking sequences coexisting in the crystal (twins of ABCABC... and ACBACB... ordering motifs), the ratio between them being 4:5 The transverse structural correlation length Ltran is 2.4 ± 0.1 μm, which corresponds to a sample thickness of 6 layers. The in-plane structural correlation length Llong is 3.4 ± 0.2 μm, and the structure mosaic is of order of 10°.
Study of Inverse Ni-based Photonic Crystal using the Microradian X-ray Diffraction

International Nuclear Information System (INIS)

Vasilieva, A V; Okorokov, A I; Grigoriev, S V; Grigoryeva, N A; Mistonov, A A; Sapoletova, N A; Napolskii, K S; Eliseev, A A; Lukashin, A V; Tretyakov, Yu D; Petukhov, A V; Byelov, D; Chernyshov, D; Bouwman, W G

2010-01-01

Inverse photonic nickel-based crystal films formed by electrocrystallization of metal inside the voids of polymer artificial opal have been studied using the microradian X-ray diffraction. Analysis of the diffraction images agrees with an face-centred cubic (FCC) structure with the lattice constant a 0 = 650 ± 10 nm and indicates two types of stacking sequences coexisting in the crystal (twins of ABCABC... and ACBACB... ordering motifs), the ratio between them being 4:5 The transverse structural correlation length L tran is 2.4 ± 0.1 μm, which corresponds to a sample thickness of 6 layers. The in-plane structural correlation length L long is 3.4 ± 0.2 μm, and the structure mosaic is of order of 10 0 .
Study of Inverse Ni-based Photonic Crystal using the Microradian X-ray Diffraction

Energy Technology Data Exchange (ETDEWEB)

Vasilieva, A V; Okorokov, A I; Grigoriev, S V [Petersburg Nuclear Physics Institute, Gatchina, 188350, St. Petersburg (Russian Federation); Grigoryeva, N A; Mistonov, A A [Department of Physics, St. Petersburg State University, 198504, St. Petersburg (Russian Federation); Sapoletova, N A; Napolskii, K S; Eliseev, A A; Lukashin, A V; Tretyakov, Yu D [Department of Materials Science, Moscow State University, 119899, Moscow (Russian Federation); Petukhov, A V; Byelov, D [Debye Institute, Utrecht University, 3584 CH Utrecht (Netherlands); Chernyshov, D [SNBL European Synchrotron Radiation Facility (ESRF), 38043 Grenoble (France); Bouwman, W G, E-mail: vasilieva@lns.pnpi.spb.r [Delft Technical University, 2629 JB Delft (Netherlands)

2010-10-01

Inverse photonic nickel-based crystal films formed by electrocrystallization of metal inside the voids of polymer artificial opal have been studied using the microradian X-ray diffraction. Analysis of the diffraction images agrees with an face-centred cubic (FCC) structure with the lattice constant a{sub 0} = 650 {+-} 10 nm and indicates two types of stacking sequences coexisting in the crystal (twins of ABCABC... and ACBACB... ordering motifs), the ratio between them being 4:5 The transverse structural correlation length L{sub tran} is 2.4 {+-} 0.1 {mu}m, which corresponds to a sample thickness of 6 layers. The in-plane structural correlation length L{sub long} is 3.4 {+-} 0.2 {mu}m, and the structure mosaic is of order of 10{sup 0}.
Precipitation of thin-film organic single crystals by a novel crystal growth method using electrospray and ionic liquid film

Science.gov (United States)

Ueda, Hiroyuki; Takeuchi, Keita; Kikuchi, Akihiko

2018-04-01

We report an organic single crystal growth technique, which uses a nonvolatile liquid thin film as a crystal growth field and supplies fine droplets containing solute from the surface of the liquid thin film uniformly and continuously by electrospray deposition. Here, we investigated the relationships between the solute concentration of the supplied solution and the morphology and size of precipitated crystals for four types of fluorescent organic low molecule material [tris(8-hydroxyquinoline)aluminum (Alq3), 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), N,N‧-bis(3-methylphenyl)-N,N‧-diphenylbenzidine (TPD), and N,N-bis(naphthalene-1-yl)-N,N-diphenyl-benzidine (NPB)] using an ionic liquid as the nonvolatile liquid. As the concentration of the supplied solution decreased, the morphology of precipitated crystals changed from dendritic or leaf shape to platelike one. At the solution concentration of 0.1 mg/ml, relatively large platelike single crystals with a diagonal length of over 100 µm were obtained for all types of material. In the experiment using ionic liquid and dioctyl sebacate as nonvolatile liquids, it was confirmed that there is a clear positive correlation between the maximum volume of the precipitated single crystal and the solubility of solute under the same solution supply conditions.
Crystal-liquid-gas phase transitions and thermodynamic similarity

CERN Document Server

Skripov, Vladimir P; Schmelzer, Jurn W P

2006-01-01

Professor Skripov obtained worldwide recognition with his monograph ""Metastable liquids"", published in English by Wiley & Sons. Based upon this work and another monograph published only in Russia, this book investigates the behavior of melting line and the properties of the coexisting crystal and liquid phase of simple substances across a wide range of pressures, including metastable states of the coexisting phases. The authors derive new relations for the thermodynamic similarity for liquid-vapour phase transition, as well as describing solid-liquid, liquid-vapor and liquid-liquid phase tra
Dichroic dye-dependent studies in guest-host polymer-dispersed liquid crystal films

Energy Technology Data Exchange (ETDEWEB)

Malik, Praveen, E-mail: pmalik100@yahoo.co [Department of Physics, Dr. B.R. Ambedkar National Institute of Technology, Jalandhar 144011, Punjab (India); Raina, K.K. [Liquid Crystal Group, Materials Research Laboratory, School of Physics and Materials Science, Thapar University, Patiala 147004, Punjab (India)

2010-01-01

Guest-host polymer-dispersed liquid crystal (GHPDLC) films were prepared using a nematic liquid crystal, photo-curable polymer and dichroic dye (anthraquinone blue) by polymerization-induced phase separation (PIPS) technique. Non-ionic dichroic dye (1%, 2% and 4% wt./wt. ratio) was taken as guest in PDLC host. Polarizing microscopy shows that in the absence of electric field, liquid crystal (LC) droplets in polymer matrix mainly exhibit bipolar configuration, however, relatively at higher field, maltese-type crosses were observed. Our results show that approx1% dye-doped PDLC film shows better transmission and faster response times over pure polymer-dispersed nematic liquid crystal (PDNLC) and higher concentrated (2% and 4%) GHPDLC films.
Dichroic dye-dependent studies in guest-host polymer-dispersed liquid crystal films

International Nuclear Information System (INIS)

Malik, Praveen; Raina, K.K.

2010-01-01

Guest-host polymer-dispersed liquid crystal (GHPDLC) films were prepared using a nematic liquid crystal, photo-curable polymer and dichroic dye (anthraquinone blue) by polymerization-induced phase separation (PIPS) technique. Non-ionic dichroic dye (1%, 2% and 4% wt./wt. ratio) was taken as guest in PDLC host. Polarizing microscopy shows that in the absence of electric field, liquid crystal (LC) droplets in polymer matrix mainly exhibit bipolar configuration, however, relatively at higher field, maltese-type crosses were observed. Our results show that ∼1% dye-doped PDLC film shows better transmission and faster response times over pure polymer-dispersed nematic liquid crystal (PDNLC) and higher concentrated (2% and 4%) GHPDLC films.
IR Sensor Synchronizing Active Shutter Glasses for 3D HDTV with Flexible Liquid Crystal Lenses

Directory of Open Access Journals (Sweden)

Jeong In Han

2013-12-01

Full Text Available IR sensor synchronizing active shutter glasses for three-dimensional high definition television (3D HDTV were developed using a flexible liquid crystal (FLC lens. The FLC lens was made on a polycarbonate (PC substrate using conventional liquid crystal display (LCD processes. The flexible liquid crystal lens displayed a maximum transmission of 32% and total response time of 2.56 ms. The transmittance, the contrast ratio and the response time of the flexible liquid crystal lens were superior to those of glass liquid crystal lenses. Microcontroller unit and drivers were developed as part of a reception module with power supply for the IR sensor synchronizing active shutter glasses with the flexible liquid crystal lens prototypes. IR sensor synchronizing active shutter glasses for 3D HDTV with flexible liquid crystal lenses produced excellent 3D images viewing characteristics.
Purification, crystallization and preliminary X-ray diffraction study of human ribosomal protein L10 core domain

International Nuclear Information System (INIS)

Nishimura, Mitsuhiro; Kaminishi, Tatsuya; Kawazoe, Masahito; Shirouzu, Mikako; Takemoto, Chie; Yokoyama, Shigeyuki; Tanaka, Akiko; Sugano, Sumio; Yoshida, Takuya; Ohkubo, Tadayasu; Kobayashi, Yuji

2007-01-01

A truncated variant of human ribosomal protien L10 was prepared and crystallized. Diffraction data were collected to 2.5 Å resolution. Eukaryotic ribosomal protein L10 is an essential component of the large ribosomal subunit, which organizes the architecture of the aminoacyl-tRNA binding site. The human L10 protein is also called the QM protein and consists of 214 amino-acid residues. For crystallization, the L10 core domain (L10CD, Phe34–Glu182) was recombinantly expressed in Escherichia coli and purified to homogeneity. A hexagonal crystal of L10CD was obtained by the sitting-drop vapour-diffusion method. The L10CD crystal diffracted to 2.5 Å resolution and belongs to space group P3 1 21 or P3 2 21
The liquid protein phase in crystallization: a case study—intact immunoglobulins

Science.gov (United States)

Kuznetsov, Yurii G.; Malkin, Alexander J.; McPherson, Alexander

2001-11-01

A common observation by protein chemists has been the appearance, for many proteins in aqueous solutions, of oil like droplets, or in more extreme cases the formation of a second oil like phase. These may accompany the formation of precipitate in "salting out" or "salting in' procedures, but more commonly appear in place of any precipitate. Such phase separations also occur, with even greater frequency, in the presence of polymeric precipitants such as polyethyleneglycol (PEG). In general the appearance of a second liquid phase has been taken as indicative of protein aggregation, though an aggregate state distinctly different from that characteristic of amorphous precipitate. While the latter is thought to be composed of linear and branched assemblies, polymers of a sort, the oil phase suggests a more compact, three-dimensional, but fluid state. An important property of an alternate, fluid phase is that it can mediate transitions between other states, for example, between protein molecules free in solution and protein molecules immobilized in amorphous precipitate or crystals. The "liquid protein" phase can be readily observed in many crystallization experiments either prior to the appearance of visible crystals, or directly participating in the crystal growth process. In some cases the relationship between the liquid phase and developing crystals is intimate. Crystals grow directly from the liquid phase, or appear only after the visible formation of the liquid phase. We describe here our experience with a class of macromolecules, immunoglobulins, and particularly IDEC-151, an IgG specific for CD4 on human lymphocytes. This protein has been crystallized from a Jeffamine-LiSO 4 mother liquor and, its crystallization illustrates many of the features associated with the liquid protein, or protein rich phase.
First observation of new effects at the set-up for searching for a neutron electric dipole moment by a crystal-diffraction method

CERN Document Server

Fedorov, V V; Semenikhin, S Y; Voronin, V V

2002-01-01

First observation of new effects was carried out using the set-up created for searching for a neutron electric dipole moment (EDM) by a crystal-diffraction method. For the first time the neutron dynamical Laue diffraction for the Bragg angles close to a right angle (up to 87 ) was studied, using the direct diffraction beam and a thick (propor to 3.5-cm) crystal. The effect of an essential time delay of diffracting neutrons inside the crystal for Bragg angles close to 90 was experimentally observed, using a time-of-flight method. The phenomenon of neutron-beam depolarization was first experimentally observed for the case of Laue diffraction in a noncentrosymmetric alpha-quartz crystal. It is experimentally proved that the interplanar electric field, affecting a neutron in a crystal, maintains its value up to Bragg angles equal to 87 . These results confirm the opportunity to increase by more than an order of magnitude the sensitivity of the method to the neutron EDM, using the diffraction angles close to 90 , ...
Crystal structure analysis of LaMnO_3 with x-ray diffraction technique using the Rietveld method

International Nuclear Information System (INIS)

Engkir Sukirman; Wisnu Ari Adi; Yustinus Purwamargapratala

2010-01-01

Crystal structure analysis of LaMnO_3 using the Rietveld method has been carried out. The LaMnO_3 sample was synthesized with high energy mechanical milling from the raw materials of La_2O_3 and MnO_2 with the appropriate mol ratio. Milling were performed for 10 hours, pelletized and hereinafter sintered at 1350 °C for 6 hours. The sample characterizations covered the crystal structure and electric-magnetic properties of the materials by X-ray diffraction technique using the Rietveld method and the four point probe, respectively. The Rietveld refinement results based on the X-rays diffraction data indicate that the sample of LaMnO_3 is single phase with the crystal system: orthorhombic, the space group: Pnma No. 62 and the lattice parameters: a = 55.4405(9) Å; b = 7.717(1) Å dan c = 5.537(1) Å. The material owns Magnetic Resonance (MR) respond of 7 %, the mean value of crystallite size, D = 17 nm and lattice strain, e = - 0.5 %. So, the material go through a compressive strain, and according to the Nanda's strain model, it becomes a type G antiferromagnetic insulator. Because the insulator properties of the material does not change although being hit by the external magnetic field, hence the MR respond is only caused by the order of electron spin. Therefore at room temperature, LaMnO_3_._0 just exhibits a small MR respond. (author)
40-Tesla pulsed-field cryomagnet for single crystal neutron diffraction

Science.gov (United States)

Duc, F.; Tonon, X.; Billette, J.; Rollet, B.; Knafo, W.; Bourdarot, F.; Béard, J.; Mantegazza, F.; Longuet, B.; Lorenzo, J. E.; Lelièvre-Berna, E.; Frings, P.; Regnault, L.-P.

2018-05-01

We present the first long-duration and high duty cycle 40-T pulsed-field cryomagnet addressed to single crystal neutron diffraction experiments at temperatures down to 2 K. The magnet produces a horizontal field in a bi-conical geometry, ±15° and ±30° upstream and downstream of the sample, respectively. Using a 1.15 MJ mobile generator, magnetic field pulses of 100 ms length are generated in the magnet, with a rise time of 23 ms and a repetition rate of 6-7 pulses per hour at 40 T. The setup was validated for neutron diffraction on the CEA-CRG three-axis spectrometer IN22 at the Institut Laue Langevin.
OPTIMIZATION OF ELECTROMAGNETIC WAVE PROPAGATION THROUGH A HETEROGENEOUS LIQUID CRYSTAL LAYER

OpenAIRE

Winslow, Michael A.

2013-01-01

Advances in technology have given way to concepts in warfare that were once constrained to the world of science fiction. In an effort to stay ahead of any potential adversarys weapons development, we must look down the path of countermeasures to high-energy electromagnetic weapons. In the attempt to engineer a material that can reduce transmitted beam intensity by the greatest factor, we look to liquid crystals. They have great potential to provide a starting point to engineer a material in o...
Purification, crystallization and preliminary X-ray diffraction of human S100A15

Energy Technology Data Exchange (ETDEWEB)

Boeshans, Karen M. [X-ray Crystallography Facility, NIAMS, National Institutes of Health, Bethesda, MD 20892 (United States); Wolf, Ronald; Voscopoulos, Christopher [Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 (United States); Gillette, William; Esposito, Dominic [Protein Expression Laboratory, Research Technology Program, National Cancer Institute, SAIC-Frederick Inc., Frederick, MD 21702 (United States); Mueser, Timothy C. [Department of Chemistry, University of Toledo, Toledo, OH 43606 (United States); Yuspa, Stuart H. [Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 (United States); Ahvazi, Bijan, E-mail: ahvazib@mail.nih.gov [X-ray Crystallography Facility, NIAMS, National Institutes of Health, Bethesda, MD 20892 (United States)

2006-05-01

S100 proteins are differentially expressed during epithelial cell maturation, tumorigenesis and inflammation. The novel human S100A15 protein has been cloned, expressed, purified and crystallized in two crystal forms, a triclinic and a monoclinic form, which diffract to 1.7 and 2.0 Å, respectively. Human S100A15 is a novel member of the S100 family of EF-hand calcium-binding proteins and was recently identified in psoriasis, where it is significantly upregulated in lesional skin. The protein is implicated as an effector in calcium-mediated signal transduction pathways. Although its biological function is unclear, the association of the 11.2 kDa S100A15 with psoriasis suggests that it contributes to the pathogenesis of the disease and could provide a molecular target for therapy. To provide insight into the function of S100A15, the protein was crystallized to visualize its structure and to further the understanding of how the many similar calcium-binding mediator proteins in the cell distinguish their cognate target molecules. The S100A15 protein has been cloned, expressed and purified to homogeneity and produced two crystal forms. Crystals of form I are triclinic, with unit-cell parameters a = 33.5, b = 44.3, c = 44.8 Å, α = 71.2, β = 68.1, γ = 67.8° and an estimated two molecules in the asymmetric unit, and diffract to 1.7 Å resolution. Crystals of form II are monoclinic, with unit-cell parameters a = 82.1, b = 33.6, c = 52.2 Å, β = 128.2° and an estimated one molecule in the asymmetric unit, and diffract to 2.0 Å resolution. This structural analysis of the human S100A15 will further aid in the phylogenic comparison between the other members of the S100 protein family, especially the highly homologous paralog S100A7.
Optimized Wavelength-Tuned Nonlinear Frequency Conversion Using a Liquid Crystal Clad Waveguide

Science.gov (United States)

Stephen, Mark A. (Inventor)

2018-01-01

An optimized wavelength-tuned nonlinear frequency conversion process using a liquid crystal clad waveguide. The process includes implanting ions on a top surface of a lithium niobate crystal to form an ion implanted lithium niobate layer. The process also includes utilizing a tunable refractive index of a liquid crystal to rapidly change an effective index of the lithium niobate crystal.
Dependence of partial molecules surface area on the third component in lyotropic liquid crystals

International Nuclear Information System (INIS)

Badalyan, H.G.; Ghazaryan, Kh.M.; Yayloyan, S.M.

2015-01-01

Free surface of one amphiphilic molecule head of a lyotropic liquid crystal has been investigated by X-Ray diffraction method, at small and large angles, in the presence of the third component. The pentadecilsulphonat-water system in the presence of cholesterol as well as the lecithin-water system in the presence of decanol were investigated. It is shown that the above mentioned free surface decreases if the cholesterol concentration increases, while this surface increases in the case of water concentration increase. However, it increases slower than in the case of the two-component system. The same is observed for the lecithin-water-decanol system
A dark hollow beam from a selectively liquid-filled photonic crystal fibre

International Nuclear Information System (INIS)

Mei-Yan, Zhang; Shu-Guang, Li; Yan-Yan, Yao; Bo, Fu; Lei, Zhang

2010-01-01

This paper reports that, based on the electromagnetic scattering theory of the multipole method, a high-quality hollow beam is produced through a selectively liquid-filled photonic crystal fibre. Instead of a doughnut shape, a typical hollow beam is produced by other methods; the mode-field images of the hollow-beam photonic crystal fibre satisfy sixth-order rotation symmetry, according to the symmetry of the photonic crystal fibre (PCF) structure. A dark spot size of the liquid-filled photonic crystal fibre-generated hollow beam can be tuned by inserting liquid into the cladding region and varying the photonic crystal fibre structure parameters. The liquid-filled PCF makes a convenient and flexible tool for the guiding and trapping of atoms and the creation of all-fibre optical tweezers. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Liquid Crystal Gel Reduces Age Spots by Promoting Skin Turnover

Directory of Open Access Journals (Sweden)

Mina Musashi

2014-07-01

Full Text Available Studies have shown that liquid crystals structurally resembling the intercellular lipids in the stratum corneum can beneficially affect the skin when applied topically by stimulating the skin’s natural regenerative functions and accelerating epidermal turnover. In the present study, the effects of applying low concentrations of a liquid crystal gel of our own creation were evaluated using epidermal thickening in mouse skin as an assay for effective stimulation of epidermal turnover. A liquid crystal gel was also applied topically to human facial skin, and analysis was conducted using before-and-after photographs of age spots, measurements of L* values that reflect degree of skin pigmentation, single-layer samples of the stratum corneum obtained via tape-stripping, and measurements of trans-epidermal water loss that reflect the status of the skin’s barrier function. The results suggested that cost-effective creams containing as low as 5% liquid crystal gel might be effective and safely sold as skin care products targeting age spots and other problems relating to uneven skin pigmentation.
Preliminary neutron diffraction analysis of challenging human manganese superoxide dismutase crystals.

Science.gov (United States)

Azadmanesh, Jahaun; Trickel, Scott R; Weiss, Kevin L; Coates, Leighton; Borgstahl, Gloria E O

2017-04-01

Superoxide dismutases (SODs) are enzymes that protect against oxidative stress by dismutation of superoxide into oxygen and hydrogen peroxide through cyclic reduction and oxidation of the active-site metal. The complete enzymatic mechanisms of SODs are unknown since data on the positions of hydrogen are limited. Here, methods are presented for large crystal growth and neutron data collection of human manganese SOD (MnSOD) using perdeuteration and the MaNDi beamline at Oak Ridge National Laboratory. The crystal from which the human MnSOD data set was obtained is the crystal with the largest unit-cell edge (240 Å) from which data have been collected via neutron diffraction to sufficient resolution (2.30 Å) where hydrogen positions can be observed.
Study of solid/liquid and solid/gas interfaces in Cu–isoleucine complex by surface X-ray diffraction

International Nuclear Information System (INIS)

Ferrer, Pilar; Rubio-Zuazo, Juan; Castro, German R.

2013-01-01

The enzymes could be understood like structures formed by amino acids bonded with metals, which act as active sites. The research on the coordination of metal–amino acid complexes will bring light on the behavior of metal enzymes, due to the close relation existing between the atomic structure and the functionality. The Cu–isoleucine bond is considered as a good model system to attain a better insight into the characteristics of naturally occurring copper metalloproteins. The surface structure of metal–amino acid complex could be considered as a more realistic model for real systems under biologic working conditions, since the molecular packing is decreased. In the surface, the structural constrains are reduced, keeping the structural capability of surface complex to change as a function of the surrounding environment. In this work, we present a surface X-ray diffraction study on Cu–isoleucine complex under different ambient conditions. Cu(Ile) 2 crystals of about 5 mm × 5 mm × 1 mm have been growth, by seeding method in a supersaturated solution, presenting a surface of high quality. The sample for the surface diffraction study was mounted on a cell specially designed for solid/liquid or solid/gas interface analysis. The Cu–isoleucine crystal was measured under a protective dry N 2 gas flow and in contact with a saturated metal amino acid solution. The bulk and the surface signals were compared, showing different atomic structures. In both cases, from surface diffraction data, it is observed that the atomic structure of the top layer undergoes a clear structural deformation. A non-uniform surface relaxation is observed producing an inhomogeneous displacement of the surface atoms towards the surface normal.
Liquid-Crystal Thermosets, a New Generation of High-Performance Liquid-Crystal Polymers

Science.gov (United States)

Dingemans, Theo; Weiser, Erik; Hou, Tan; Jensen, Brian; St. Clair, Terry

2004-01-01

One of the major challenges for NASA's next-generation reusable-launch-vehicle (RLV) program is the design of a cryogenic lightweight composite fuel tank. Potential matrix resin systems need to exhibit a low coefficient of thermal expansion (CTE), good mechanical strength, and excellent barrier properties at cryogenic temperatures under load. In addition, the resin system needs to be processable by a variety of non-autoclavable techniques, such as vacuum-bag curing, resin-transfer molding (RTM), vacuum-assisted resin-transfer molding (VaRTM), resin-film infusion (RFI), pultrusion, and advanced tow placement (ATP). To meet these requirements, the Advanced Materials and Processing Branch (AMPB) at NASA Langley Research Center developed a new family of wholly aromatic liquid-crystal oligomers that can be processed and thermally cross-linked while maintaining their liquid-crystal order. All the monomers were polymerized in the presence of a cross-linkable unit by use of an environmentally benign melt-condensation technique. This method does not require hazardous solvents, and the only side product is acetic acid. The final product can be obtained as a powder or granulate and has an infinite shelf life. The obtained oligomers melt into a nematic phase and do not exhibit isotropization temperatures greater than the temperatures of decomposition (Ti > T(sub dec)). Three aromatic formulations were designed and tested and included esters, ester-amides, and ester-imides. One of the major advantages of this invention, named LaRC-LCR or Langley Research Center-Liquid Crystal Resin, is the ability to control a variety of resin characteristics, such as melting temperature, viscosity, and the cross-link density of the final part. Depending on the formulation, oligomers can be prepared with melt viscosities in the range of 10-10,000 poise (100 rad/s), which can easily be melt-processed using a variety of composite-processing techniques. This capability provides NASA with custom
Expression, purification, crystallization and preliminary X-ray diffraction analysis of Thermotoga neapolitana β-glucosidase B

Energy Technology Data Exchange (ETDEWEB)

Turner, Pernilla [Department of Biotechnology, Centre for Chemistry and Chemical Engineering, Lund University, Box 124, S-221 00 Lund (Sweden); Pramhed, Anna [Department of Molecular Biophysics, Centre for Chemistry and Chemical Engineering, Lund University, Box 124, S-221 00 Lund (Sweden); Kanders, Erik; Hedström, Martin; Karlsson, Eva Nordberg, E-mail: eva.nordberg-karlsson@biotek.lu.se [Department of Biotechnology, Centre for Chemistry and Chemical Engineering, Lund University, Box 124, S-221 00 Lund (Sweden); Logan, Derek T., E-mail: eva.nordberg-karlsson@biotek.lu.se [Department of Molecular Biophysics, Centre for Chemistry and Chemical Engineering, Lund University, Box 124, S-221 00 Lund (Sweden); Department of Biotechnology, Centre for Chemistry and Chemical Engineering, Lund University, Box 124, S-221 00 Lund (Sweden)

2007-09-01

Here, the expression, purification, crystallization and X-ray diffraction data of a family 3 β-glucosidase from the hyperthermophilic bacterium Thermotoga neapolitana are reported. β-Glucosidases belong to families 1, 3 and 9 of the glycoside hydrolases and act on cello-oligosaccharides. Family 1 and 3 enzymes are retaining and are reported to have transglycosylation activity, which can be used to produce oligosaccharides and glycoconjugates. Family 3 enzymes are less well characterized than their family 1 homologues and to date only two crystal structures have been solved. Here, the expression, purification, crystallization and X-ray diffraction data of a family 3 β-glucosidase from the hyperthermophilic bacterium Thermotoga neapolitana are reported. Crystals of selenomethionine-substituted protein have also been grown. The crystals belong to space group C222{sub 1}, with unit-cell parameters a = 74.9, b = 127.0, c = 175.2 Å. Native data have been collected to 2.4 Å resolution and the structure has been solved to 2.7 Å using the selenomethionine MAD method. Model building and refinement of the structure are under way.
Liquid contrabands classification based on energy dispersive X-ray diffraction and hybrid discriminant analysis

International Nuclear Information System (INIS)

YangDai, Tianyi; Zhang, Li

2016-01-01

Energy dispersive X-ray diffraction (EDXRD) combined with hybrid discriminant analysis (HDA) has been utilized for classifying the liquid materials for the first time. The XRD spectra of 37 kinds of liquid contrabands and daily supplies were obtained using an EDXRD test bed facility. The unique spectra of different samples reveal XRD's capability to distinguish liquid contrabands from daily supplies. In order to create a system to detect liquid contrabands, the diffraction spectra were subjected to HDA which is the combination of principal components analysis (PCA) and linear discriminant analysis (LDA). Experiments based on the leave-one-out method demonstrate that HDA is a practical method with higher classification accuracy and lower noise sensitivity than the other methods in this application. The study shows the great capability and potential of the combination of XRD and HDA for liquid contrabands classification.
Liquid contrabands classification based on energy dispersive X-ray diffraction and hybrid discriminant analysis

Energy Technology Data Exchange (ETDEWEB)

YangDai, Tianyi [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education (China); Zhang, Li, E-mail: zhangli@nuctech.com [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education (China)

2016-02-01

Energy dispersive X-ray diffraction (EDXRD) combined with hybrid discriminant analysis (HDA) has been utilized for classifying the liquid materials for the first time. The XRD spectra of 37 kinds of liquid contrabands and daily supplies were obtained using an EDXRD test bed facility. The unique spectra of different samples reveal XRD's capability to distinguish liquid contrabands from daily supplies. In order to create a system to detect liquid contrabands, the diffraction spectra were subjected to HDA which is the combination of principal components analysis (PCA) and linear discriminant analysis (LDA). Experiments based on the leave-one-out method demonstrate that HDA is a practical method with higher classification accuracy and lower noise sensitivity than the other methods in this application. The study shows the great capability and potential of the combination of XRD and HDA for liquid contrabands classification.
Liquid contrabands classification based on energy dispersive X-ray diffraction and hybrid discriminant analysis

Science.gov (United States)

YangDai, Tianyi; Zhang, Li

2016-02-01

Energy dispersive X-ray diffraction (EDXRD) combined with hybrid discriminant analysis (HDA) has been utilized for classifying the liquid materials for the first time. The XRD spectra of 37 kinds of liquid contrabands and daily supplies were obtained using an EDXRD test bed facility. The unique spectra of different samples reveal XRD's capability to distinguish liquid contrabands from daily supplies. In order to create a system to detect liquid contrabands, the diffraction spectra were subjected to HDA which is the combination of principal components analysis (PCA) and linear discriminant analysis (LDA). Experiments based on the leave-one-out method demonstrate that HDA is a practical method with higher classification accuracy and lower noise sensitivity than the other methods in this application. The study shows the great capability and potential of the combination of XRD and HDA for liquid contrabands classification.
X-ray diffraction study of stacking faults in a single crystal of 2H SiC

International Nuclear Information System (INIS)

Pandey, D.; Krishna, P.

1977-01-01

The nature of random stacking faults in a heavily disordered single crystal of 2H SiC has been investigated by studying the broadening of x-ray diffraction maxima. The intensity distribution along the 10.1 reciprocal lattice row was recorded on a four-circle, computer-controlled single crystal diffractometer. The 10.1 reflections with 1 even were found to be considerably broadened showing that the stacking faults present are predominantly intrinsic faults ( both growth and deformation faults). A careful study of the half-width values of different 10.1 reflections revealed that the fault probabilities are large. Exact expressions for the diffracted intensity and the observable diffraction effects were obtained and these were then used to calculate the deformation and growth fault probabilities which were found to be 0.20 and 0.11 respectively. It is suggested that several deformation fault configurations result from a clustering of growth faults. The results obtained are compared with those obtained for 2H ZnS crystals. (author)
Neutral-helium-atom diffraction from a micron-scale periodic structure: Photonic-crystal-membrane characterization

Science.gov (United States)

Nesse, Torstein; Eder, Sabrina D.; Kaltenbacher, Thomas; Grepstad, Jon Olav; Simonsen, Ingve; Holst, Bodil

2017-06-01

Surface scattering of neutral helium beams created by supersonic expansion is an established technique for measuring structural and dynamical properties of surfaces on the atomic scale. Helium beams have also been used in Fraunhofer and Fresnel diffraction experiments. Due to the short wavelength of the atom beams of typically 0.1 nm or less, Fraunhofer diffraction experiments in transmission have so far been limited to grating structures with a period (pitch) of up to 200 nm. However, larger periods are of interest for several applications, for example, for the characterization of photonic-crystal-membrane structures, where the period is typically in the micron to high submicron range. Here we present helium atom diffraction measurements of a photonic-crystal-membrane structure with a two-dimensional square lattice of 100 ×100 circular holes. The nominal period and the hole radius were 490 and 100 nm, respectively. To our knowledge this is the largest period that has been measured with helium diffraction. The helium diffraction measurements are interpreted using a model based on the helium beam characteristics. It is demonstrated how to successfully extract values from the experimental data for the average period of the grating, the hole diameter, and the width of the virtual source used to model the helium beam.
Crystallization and X-ray diffraction studies of crustacean proliferating cell nuclear antigen

International Nuclear Information System (INIS)

Carrasco-Miranda, Jesus S.; Cardona-Felix, Cesar S.; Lopez-Zavala, Alonso A.; Re Vega, Enrique de la; De la Mora, Eugenio; Rudiño-Piñera, Enrique; Sotelo-Mundo, Rogerio R.; Brieba, Luis G.

2012-01-01

Proliferating cell nuclear antigen from Litopenaeus vannamei was recombinantly expressed, purified and crystallized. Diffraction data were obtained and processed to 3 Å. Proliferating cell nuclear antigen (PCNA), a member of the sliding clamp family of proteins, interacts specifically with DNA replication and repair proteins through a small peptide motif called the PCNA-interacting protein or PIP box. PCNA is recognized as one of the key proteins involved in DNA metabolism. In the present study, the recombinant PCNA from Litopenaeus vannamei (LvPCNA) was heterologously overexpressed and purified using metal ion-affinity chromatography. Crystals suitable for diffraction grew overnight using the hanging-drop vapour-diffusion method. LvPCNA crystals belong to space group C2 with unit-cell parameters a = 144.6, b = 83.4, c = 74.3 Å, β = 117.6°. One data set was processed to 3 Å resolution, with an overall R meas of 0.09 and a completeness of 93.3%. Initial phases were obtained by molecular replacement using a homology model of LvPCNA as the search model. Refinement and structural analysis are underway. This report is the first successful crystallographic analysis of a marine crustacean decapod shrimp (L. vannamei) proliferating cell nuclear antigen
Thin aligned organic polymer films for liquid crystal devices

International Nuclear Information System (INIS)

Foster, Kathryn Ellen

1997-01-01

This project was designed to investigate the possibility of producing alignment layers for liquid crystal devices by cross-linking thin films containing anisotropic polymer bound chromophores via irradiation with polarised ultraviolet light. Photocross-linkable polymers find use in microelectronics, liquid crystal displays, printing and UV curable lacquers and inks; so there is an increasing incentive for the development of new varieties of photopolymers in general. The synthesis and characterisation of two new photopolymers that are suitable as potential alignment layers for liquid crystal devices are reported in this thesis. The first polymer contains the anthracene chromophore attached via a spacer unit to a methacrylate backbone and the second used a similarly attached aryl azide group. Copolymers of the new monomers with methyl methacrylate were investigated to establish reactivity ratios in order to understand composition drift during polymerisation. (author)
Perdeuteration, purification, crystallization and preliminary neutron diffraction of an ocean pout type III antifreeze protein

International Nuclear Information System (INIS)

Petit-Haertlein, Isabelle; Blakeley, Matthew P.; Howard, Eduardo; Hazemann, Isabelle; Mitschler, Andre; Haertlein, Michael; Podjarny, Alberto

2009-01-01

Perdeuterated type III antifreeze protein has been expressed, purified and crystallized. Preliminary neutron data collection showed diffraction to 1.85 Å resolution from a 0.13 mm 3 crystal. The highly homologous type III antifreeze protein (AFP) subfamily share the capability to inhibit ice growth at subzero temperatures. Extensive studies by X-ray crystallography have been conducted, mostly on AFPs from polar fishes. Although interactions between a defined flat ice-binding surface and a particular lattice plane of an ice crystal have now been identified, the fine structural features underlying the antifreeze mechanism still remain unclear owing to the intrinsic difficulty in identifying H atoms using X-ray diffraction data alone. Here, successful perdeuteration (i.e. complete deuteration) for neutron crystallographic studies of the North Atlantic ocean pout (Macrozoarces americanus) AFP in Escherichia coli high-density cell cultures is reported. The perdeuterated protein (AFP D) was expressed in inclusion bodies, refolded in deuterated buffer and purified by cation-exchange chromatography. Well shaped perdeuterated AFP D crystals have been grown in D 2 O by the sitting-drop method. Preliminary neutron Laue diffraction at 293 K using LADI-III at ILL showed that with a few exposures of 24 h a very low background and clear small spots up to a resolution of 1.85 Å were obtained using a ‘radically small’ perdeuterated AFP D crystal of dimensions 0.70 × 0.55 × 0.35 mm, corresponding to a volume of 0.13 mm 3
Crystallization and preliminary X-ray diffraction studies of l-rhamnose isomerase from Pseudomonas stutzeri

International Nuclear Information System (INIS)

Yoshida, Hiromi; Wayoon, Poonperm; Takada, Goro; Izumori, Ken; Kamitori, Shigehiro

2006-01-01

Recombinant l-rhamnose isomerase from P. stutzeri has been crystallized. Diffraction data have been collected to 2.0 Å resolution. l-Rhamnose isomerase from Pseudomonas stutzeri (P. stutzeril-RhI) catalyzes not only the reversible isomerization of l-rhamnose to l-rhamnulose, but also isomerization between various rare aldoses and ketoses. Purified His-tagged P. stutzeril-RhI was crystallized by the hanging-drop vapour-diffusion method. The crystals belong to the monoclinic space group P2 1 , with unit-cell parameters a = 74.3, b = 104.0, c = 107.0 Å, β = 106.8°. Diffraction data have been collected to 2.0 Å resolution. The molecular weight of the purified P. stutzeril-RhI with a His tag at the C-terminus was confirmed to be 47.7 kDa by MALDI–TOF mass-spectrometric analysis and the asymmetric unit is expected to contain four molecules
Spectroscopic investigation of the far-infrared properties of liquid crystals

DEFF Research Database (Denmark)

Reuter, M.; Vieweg, N.; Fischer, B. M.

2013-01-01

Liquid crystals are one of the most promising base materials for switchable devices at THz frequencies. Therefore, a precise understanding of the optical parameters is crucial. Here, we present the refractive indices and absorption coefficients for 5 CB and an isothiocyanate terminated liquid...... crystal over a broad frequency range from 0.3 THz to 15 THz....
Neutron diffraction tomography: a unique, 3D inspection technique for crystals using an intensifier TV system

International Nuclear Information System (INIS)

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

1978-01-01

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

International Nuclear Information System (INIS)

Aoi, Y; Tominaga, T

2013-01-01

Titanium dioxide (TiO 2 ) inverse opals in spherical shape were prepared by liquid phase deposition (LPD) using spherical colloidal crystals as templates. Spherical colloidal crystals were produced by ink-jet drying technique. Aqueous emulsion droplets that contain polystyrene latex particles were ejected into air and dried. Closely packed colloidal crystals with spherical shape were obtained. The obtained spherical colloidal crystals were used as templates for the LPD. The templates were dispersed in the deposition solution of the LPD, i.e. a mixed solution of ammonium hexafluorotitanate and boric acid and reacted for 4 h at 30 °C. After the LPD process, the interstitial spaces of the spherical colloidal crystals were completely filled with titanium oxide. Subsequent heat treatment resulted in removal of templates and spherical titanium dioxide inverse opals. The spherical shape of the template was retained. SEM observations indicated that the periodic ordered voids were surrounded by titanium dioxide. The optical reflectance spectra indicated that the optical properties of the spherical titanium dioxide inverse opals were due to Bragg diffractions from the ordered structure. Filling in the voids of the inverse opals with different solvents caused remarkable changes in the reflectance peak.
Crystallization and diffraction properties of the Fab fragment of 3B5H10, an antibody specific for disease-causing polyglutamine stretches

International Nuclear Information System (INIS)

Peters-Libeu, Clare; Newhouse, Yvonne; Krishnan, Preethi; Cheung, Kenneth; Brooks, Elizabeth; Weisgraber, Karl; Finkbeiner, Steven

2005-01-01

Optimization of crystallization conditions and cryoprotectants decreased the anisotropy of the diffraction obtained from 3B5H10 Fab crystals. Dehydration improved the resolution of cryoprotected 3B5H10 crystals from 2.6 to 1.9 Å, but changed the space group of the crystals from P2 1 2 1 2 to P2 1 . Because it binds soluble forms of proteins with disease-associated polyglutamine expansions, the antibody 3B5H10 is a powerful tool for studying polyglutamine-related diseases. Crystals of the 3B5H10 Fab (47 kDa) were obtained by vapor diffusion at room temperature from PEG 3350. However, the initial crystals gave highly anisotropic diffraction patterns. After optimization of the crystallization conditions and cryoprotectants, a nearly isotropic diffraction pattern at 2.6 Å resolution was achieved for crystals with unit-cell parameters a = 133.26, b = 79.52, c = 41.49 Å and space group P2 1 2 1 2. Dehydrated crystals diffracted isotropically to 1.9 Å with unit-cell parameters a = 123.65, b = 78.25, c = 42.26 Å, β = 90.3° and space group P2 1
Purification, crystallization and preliminary X-ray diffraction studies of d-tagatose 3-epimerase from Pseudomonas cichorii

Energy Technology Data Exchange (ETDEWEB)

Yoshida, Hiromi; Yamada, Mitsugu [Molecular Structure Research Group, Information Technology Center and Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793 (Japan); Nishitani, Takeyori; Takada, Goro; Izumori, Ken [Department of Biochemistry and Food Science, Faculty of Agriculture and Rare Sugar Research Center, Kagawa University, Miki-cho, Kagawa 761-0795 (Japan); Kamitori, Shigehiro, E-mail: kamitori@med.kagawa-u.ac.jp [Molecular Structure Research Group, Information Technology Center and Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793 (Japan)

2007-02-01

Recombinant d-tagatose 3-epimerase from P. cichorii was purified and crystallized. Diffraction data were collected to 2.5 Å resolution. d-Tagatose 3-epimerase (D-TE) from Pseudomonas cichorii catalyzes the epimerization of various ketohexoses at the C3 position. The epimerization of d-psicose has not been reported with epimerases other than P. cichorii D-TE and d-psicose 3-epimerase from Agrobacterium tumefaciens. Recombinant P. cichorii D-TE has been purified and crystallized. Crystals of P. cichorii D-TE were obtained by the sitting-drop method at room temperature. The crystal belongs to the monoclinic space group P2{sub 1}, with unit-cell parameters a = 76.80, b = 94.92, c = 91.73 Å, β = 102.82°. Diffraction data were collected to 2.5 Å resolution. The asymmetric unit is expected to contain four molecules.
Purification, crystallization and preliminary X-ray diffraction studies of d-tagatose 3-epimerase from Pseudomonas cichorii

International Nuclear Information System (INIS)

Yoshida, Hiromi; Yamada, Mitsugu; Nishitani, Takeyori; Takada, Goro; Izumori, Ken; Kamitori, Shigehiro

2007-01-01

Recombinant d-tagatose 3-epimerase from P. cichorii was purified and crystallized. Diffraction data were collected to 2.5 Å resolution. d-Tagatose 3-epimerase (D-TE) from Pseudomonas cichorii catalyzes the epimerization of various ketohexoses at the C3 position. The epimerization of d-psicose has not been reported with epimerases other than P. cichorii D-TE and d-psicose 3-epimerase from Agrobacterium tumefaciens. Recombinant P. cichorii D-TE has been purified and crystallized. Crystals of P. cichorii D-TE were obtained by the sitting-drop method at room temperature. The crystal belongs to the monoclinic space group P2 1 , with unit-cell parameters a = 76.80, b = 94.92, c = 91.73 Å, β = 102.82°. Diffraction data were collected to 2.5 Å resolution. The asymmetric unit is expected to contain four molecules

Cloning, expression, purification, crystallization and preliminary X-ray diffraction analysis of glyoxalase I from Leishmania infantum

International Nuclear Information System (INIS)

Barata, Lídia; Sousa Silva, Marta; Schuldt, Linda; Costa, Gonçalo da; Tomás, Ana M.; Ferreira, António E. N.; Weiss, Manfred S.; Ponces Freire, Ana; Cordeiro, Carlos

2010-01-01

Glyoxalase I from L. infantum was cloned, overexpressed in E. coli, purified and crystallized. Glyoxalase I (GLO1) is the first of the two glyoxalase-pathway enzymes. It catalyzes the formation of S-d-lactoyltrypanothione from the non-enzymatically formed hemithioacetal of methylglyoxal and reduced trypanothione. In order to understand its substrate binding and catalytic mechanism, GLO1 from Leishmania infantum was cloned, overexpressed in Escherichia coli, purified and crystallized. Two crystal forms were obtained: a cube-shaped form and a rod-shaped form. While the cube-shaped form did not diffract X-rays at all, the rod-shaped form exhibited diffraction to about 2.0 Å resolution. The crystals belonged to space group P2 1 2 1 2, with unit-cell parameters a = 130.03, b = 148.51, c = 50.63 Å and three dimers of the enzyme per asymmetric unit
Induced Smectic X Phase Through Intermolecular Hydrogen-Bonded Liquid Crystals Formed Between Citric Acid and p- n-(Octyloxy)Benzoic Acid

Science.gov (United States)

Sundaram, S.; Subhasri, P.; Rajasekaran, T. R.; Jayaprakasam, R.; Senthil, T. S.; Vijayakumar, V. N.

2017-08-01

Hydrogen-bonded liquid crystal (HBLC) is synthesized from citric acid (CA) and 4-(octyloxy)benzoic acid (8OBA) with different mole ratios. Fourier transform infrared spectroscopy (FT-IR) confirms the presence of hydrogen bond between CA and 8OBA. Nuclear magnetic resonance (NMR) spectroscopic studies validate the intermolecular complementary, cyclic type of hydrogen bond, and molecular environment in the designed HBLC complex. Powder X-ray diffraction analysis reveals the monoclinic nature of liquid crystal complex in solid phase. Liquid crystal parameters such as phase transition temperature and enthalpy values for the corresponding mesogenic phases are investigated using a polarizing optical microscope (POM) and differential scanning calorimetry (DSC). It is observed that the change in chain length and steric hindrance while increasing the mole ratio in HBLC complex induces a new smectic X (Sm X) along with higher-order smectic G (Sm G) phases by quenching of smectic C (Sm C). From the experimental observations, induced Sm X phase has been identified as a finger print texture. Also, Sm G is a multi-colored mosaic texture in 1:1, 1:2, and 1:3 mol ratios. The optical tilt angle, thermal stability factor, and enhanced thermal span width of CA + 8OBA complex are discussed.
Do protein crystals nucleate within dense liquid clusters?

International Nuclear Information System (INIS)

Maes, Dominique; Vorontsova, Maria A.; Potenza, Marco A. C.; Sanvito, Tiziano; Sleutel, Mike; Giglio, Marzio; Vekilov, Peter G.

2015-01-01

The evolution of protein-rich clusters and nucleating crystals were characterized by dynamic light scattering (DLS), confocal depolarized dynamic light scattering (cDDLS) and depolarized oblique illumination dark-field microscopy. Newly nucleated crystals within protein-rich clusters were detected directly. These observations indicate that the protein-rich clusters are locations for crystal nucleation. Protein-dense liquid clusters are regions of high protein concentration that have been observed in solutions of several proteins. The typical cluster size varies from several tens to several hundreds of nanometres and their volume fraction remains below 10 −3 of the solution. According to the two-step mechanism of nucleation, the protein-rich clusters serve as locations for and precursors to the nucleation of protein crystals. While the two-step mechanism explained several unusual features of protein crystal nucleation kinetics, a direct observation of its validity for protein crystals has been lacking. Here, two independent observations of crystal nucleation with the proteins lysozyme and glucose isomerase are discussed. Firstly, the evolutions of the protein-rich clusters and nucleating crystals were characterized simultaneously by dynamic light scattering (DLS) and confocal depolarized dynamic light scattering (cDDLS), respectively. It is demonstrated that protein crystals appear following a significant delay after cluster formation. The cDDLS correlation functions follow a Gaussian decay, indicative of nondiffusive motion. A possible explanation is that the crystals are contained inside large clusters and are driven by the elasticity of the cluster surface. Secondly, depolarized oblique illumination dark-field microscopy reveals the evolution from liquid clusters without crystals to newly nucleated crystals contained in the clusters to grown crystals freely diffusing in the solution. Collectively, the observations indicate that the protein-rich clusters in
AC electric field assisted orientational photorefractive effect in C60-doped nematic liquid crystal

International Nuclear Information System (INIS)

Sun Xiudong; Pei Yanbo; Yao Fengfeng; Zhang Jianlong; Hou Chunfeng

2007-01-01

Photorefractive gratings were produced in a C 60 -doped nematic liquid crystal cell under the application of two coherent beams and a nonbiased sinusoidal ac electric field. The beam coupling and diffraction of the ac electric field assisted gratings were studied systematically. A stable asymmetric energy transference was obtained. Diffraction was observed when the angle (between the normal of the cell and the bisector of the writing beams) was 0 0 , and the dependence of diffraction efficiency on the peak-to-peak value of the ac voltage was similar to that at an incidence angle of 45 0 , suggesting that the role of the ac field was to facilitate the charge separation, and the space-charge field (SCF) originated predominantly from the diffusion of the ac electric field assisted photo-induced carriers under the application of nonuniform illumination and an applied ac field. The grating was produced by director reorientation induced by the cooperation of the SCF and the applied ac electric field. A self-erasing phenomenon was observed in this cell. An explanation in terms of the movement of two kinds of carriers with opposite signs was proposed
Cloning, expression, purification, crystallization and preliminary X-ray diffraction analysis of the regulator AcrR from Escherichia coli

International Nuclear Information System (INIS)

Li, Ming; Qiu, Xi; Su, Chih-Chia; Long, Feng; Gu, Ruoyu; McDermott, Gerry; Yu, Edward W.

2006-01-01

The transcriptional regulator AcrR from Escherichia coli has been cloned, overexpressed, purified and crystallized and X-ray diffraction data have been collected to a resolution of 2.5 Å. This paper describes the cloning, expression, purification and preliminary X-ray data analysis of the AcrR regulatory protein. The Escherichia coli AcrR is a member of the TetR family of transcriptional regulators. It regulates the expression of the AcrAB multidrug transporter. Recombinant AcrR with a 6×His tag at the C-terminus was expressed in E. coli and purified by metal-affinity chromatography. The protein was crystallized using hanging-drop vapor diffusion. X-ray diffraction data were collected from cryocooled crystals at a synchrotron light source. The best crystal diffracted to 2.5 Å. The space group was determined to be P3 2 , with unit-cell parameters a = b = 46.61, c = 166.16 Å
Old and new ideas in ferroelectric liquid crystal technology

Science.gov (United States)

Lagerwall, Sven T.; Matuszczyk, M.; Matuszczyk, T.

1998-02-01

Ferroelectric liquid crystals (FLC) are to conventional liquid crystal what Gallium Arsenide is to Silicon in the semiconductor area. The first generation of FLC displays in now present on the market and has some outstanding features based on the symmetric bistability which may be achieved in these materials. One of the greatest challenges for the next generation is to achieve an analog grey scale out of an essentially digital principle. We will analyze in some detail which major problems had to be solved to reach the present state and show how the final steps could be taken toward a new state-of-the-art level in liquid crystal devices. In the last decade university research and industrial R and D have almost equally contributed to treat the very serious complications caused by the so-called chevron structures We will review this important topic in particular detail.
Multiplexing schemes for an achromatic programmable diffractive lens

Energy Technology Data Exchange (ETDEWEB)

Millan, M S; Perez-Cabre, E; Oton, J [Technical University of Catalonia, Dep. Optics and Optometry, Terrassa-Barcelona, 08222 (Spain)], E-mail: millan@oo.upc.edu

2008-11-01

A multiplexed programmable diffractive lens, displayed on a pixelated liquid crystal device under broadband illumination, is proposed to compensate for the severe chromatic aberration that affects diffractive elements. The proposed lens is based on multiplexing a set of sublenses with a common focal length for different wavelengths. We consider different types of integration of the optical information (spatial only, temporal only and hybrid spatial-temporal) combined with a proper selection of the spectral bandwidth. The properties and limits of the achromatic programmable multiplexed lens are described. Experimental results are presented and discussed.
Multiplexing schemes for an achromatic programmable diffractive lens

International Nuclear Information System (INIS)

Millan, M S; Perez-Cabre, E; Oton, J

2008-01-01

A multiplexed programmable diffractive lens, displayed on a pixelated liquid crystal device under broadband illumination, is proposed to compensate for the severe chromatic aberration that affects diffractive elements. The proposed lens is based on multiplexing a set of sublenses with a common focal length for different wavelengths. We consider different types of integration of the optical information (spatial only, temporal only and hybrid spatial-temporal) combined with a proper selection of the spectral bandwidth. The properties and limits of the achromatic programmable multiplexed lens are described. Experimental results are presented and discussed.
Ion Density Analysis of Single-Stranded DNA in Liquid Crystal

Science.gov (United States)

Iwabata, Kazuki; Seki, Yasutaka; Toizumi, Ryota; Shimada, Yuki; Furue, Hirokazu; Sakaguchi, Kengo

2013-09-01

With the widespread use of liquid crystals (LCs) in liquid crystal displays, we have looked into the application of liquid crystals in biotechnology. The purpose of the study described here is to investigate the physical properties of DNA using LCs. Synthetic oligonucleotide molecules were dispersed in MLC6884, the sample injected into antiparallel cells, and the amount of mobile ions was measured. The LC cell doped with oligonucleotide molecules showed a sequence-dependent, specific correlation between oligonucleotide concentration and the amount of mobile ions in the LC cells. In the framework of the Stokes model and polyacrylamide gel electrophoresis (PAGE) analysis, we speculate that this result arises from the difference in ion mobility, which is caused by the shape of the oligonucleotide molecule in the LC.
Expression, purification, crystallization and preliminary X-ray diffraction analysis of Arabidopsis thaliana cyclophilin 38 (AtCyp38)

International Nuclear Information System (INIS)

Vasudevan, Dileep; Gopalan, Gayathri; He, Zengyong; Luan, Sheng; Swaminathan, Kunchithapadam

2005-01-01

Crystallization of Arabidopsis thaliana cyclophilin 38. The crystal diffracts X-rays to 2.5 Å resolution. AtCyp38 is one of the highly divergent multidomain cyclophilins from Arabidopsis thaliana. A recombinant form of AtCyp38 (residues 83–437) was expressed in Escherichia coli and purified to homogeneity. The protein was crystallized using the vapour-batch technique with PEG 6000 and t-butanol as precipitants. Crystals of recombinant AtCyp38 diffracted X-rays to better than 2.5 Å resolution at 95 K using a synchrotron-radiation source. The crystal belongs to the C-centred orthorhombic space group C222 1 , with unit-cell parameters a = 58.2, b = 95.9, c = 167.5 Å, and contains one molecule in the asymmetric unit. The selenomethionine derivative of the AtCyp38 protein was overexpressed, purified and crystallized in the same space group and data were collected to 3.5 Å at the NSLS synchrotron. The structure is being solved by the MAD method
Crystallization and preliminary X-ray diffraction studies of Murraya koenigii trypsin inhibitor

Energy Technology Data Exchange (ETDEWEB)

Shee, Chandan [Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247 667 (India); Singh, Tej P. [Department of Biophysics, All India Institute of Medical Sciences, New Delhi 100 029 (India); Kumar, Pravindra, E-mail: kumarfbs@iitr.ernet.in; Sharma, Ashwani K., E-mail: kumarfbs@iitr.ernet.in [Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247 667 (India)

2007-04-01

A Kunitz-type trypsin inhibitor purified from the seeds of Murraya koenigii has been crystallized by the sitting-drop vapour-diffusion method using PEG 8000 as the precipitating agent. A Kunitz-type trypsin inhibitor purified from the seeds of Murraya koenigii has been crystallized by the sitting-drop vapour-diffusion method using PEG 8000 as the precipitating agent. The crystals belong to the tetragonal space group P4{sub 3}2{sub 1}2, with unit-cell parameters a = b = 75.8, c = 150.9 Å. The crystals contain two molecules in the asymmetric unit with a V{sub M} value of 2.5 Å{sup 3} Da{sup −1}. Diffraction was observed to 2.65 Å resolution and a complete data set was collected to 2.9 Å resolution.
Characterization of an Yb:LuVO{sub 4} single crystal using X-ray topography, high-resolution X-ray diffraction, and X-ray photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Paszkowicz, W., E-mail: paszk@ifpan.edu.pl [Institute of Physics, Polish Academy of Sciences, al. Lotnikow 32/46, PL-02668 Warsaw (Poland); Romanowski, P.; Bak-Misiuk, J. [Institute of Physics, Polish Academy of Sciences, al. Lotnikow 32/46, PL-02668 Warsaw (Poland); Wierzchowski, W. [Institute of Electronic Materials Technology, Wolczynska 133, PL-01919 Warsaw (Poland); Wieteska, K. [Institute of Atomic Energy POLATOM, PL-05400 Otwock-Swierk (Poland); Graeff, W. [HASYLAB at DESY, Notkestr. 85, D-22603 Hamburg (Germany); Iwanowski, R.J. [Institute of Physics, Polish Academy of Sciences, al. Lotnikow 32/46, PL-02668 Warsaw (Poland); Heinonen, M.H. [Laboratory of Materials Science, Department of Physics, University of Turku, Vesilinnantie 5, FI-20014, Turku (Finland); Ermakova, O. [Institute of Physics, Polish Academy of Sciences, al. Lotnikow 32/46, PL-02668 Warsaw (Poland); Dabkowska, H. [Department of Physics, McMaster University, Hamilton, Ontario, L8S 4M1 (Canada)

2011-10-15

Knowledge on the defect and electronic structure allows for improved modeling of material properties. A short literature review has shown that the information on defect structure of rare earth orthovanadate single crystals is limited. In this paper, defect and electronic structure of a needle-shaped Yb:LuVO{sub 4} single crystal grown by the slow cooling method have been studied by means of X-ray diffraction topography employing white synchrotron beam, high-resolution diffraction (HRD) and photoelectron spectroscopy (XPS) techniques. Topographic investigations show that the crystal is composed of two blocks disoriented by about 1.5{sup o} and separated by a narrow deformed region. Some contrasts observed within the crystal volume may be attributed to glide bands and sector boundaries. The contrasts appearing in the vicinity of the surface may be interpreted as due to the presence of small inclusions. The HRD study indicates, in particular, that among point defects, the vacancy type defects dominate and that the density of other defects is small in comparison. The XPS measurements enabled, despite highly insulating properties of the studied crystal, an analysis of its bulk electronic structure, including the main core-levels (O 1s, V 2p, Lu 4f) as well as the valence band range.
Small-angle light scattering symmetry breaking in polymer-dispersed liquid crystal films with inhomogeneous electrically controlled interface anchoring

Energy Technology Data Exchange (ETDEWEB)

Loiko, V. A., E-mail: loiko@ifanbel.bas-net.by; Konkolovich, A. V. [National Academy of Sciences of Belarus, Stepanov Institute of Physics (Belarus); Zyryanov, V. Ya. [Russian Academy of Sciences, Kirensky Institute of Physics, Federal Research Center “Krasnoyarsk Scientific Center,” Siberian Branch (Russian Federation); Miskevich, A. A. [National Academy of Sciences of Belarus, Stepanov Institute of Physics (Belarus)

2017-03-15

We have described the method of analyzing and reporting on the results of calculation of the small-angle structure of radiation scattered by a polymer-dispersed liquid crystal film with electrically controlled interfacial anchoring. The method is based on the interference approximation of the wave scattering theory and the hard disk model. Scattering from an individual liquid crystal droplet has been described using the anomalous diffraction approximation extended to the case of droplets with uniform and nonuniform interface anchoring at the droplet–polymer boundary. The director field structure in an individual droplet is determined from the solution of the problem of minimizing the volume density of the free energy. The electrooptical effect of symmetry breaking in the angular distribution of scattered radiation has been analyzed. This effect means that the intensities of radiation scattered within angles +θ{sub s} and–θ{sub s} relative to the direction of illumination in the scattering plane can be different. The effect is of the interference origin and is associated with asymmetry of the phase shift of the wavefront of an incident wave from individual parts of the droplet, which appears due to asymmetry of the director field structure in the droplet, caused by nonuniform anchoring of liquid crystal molecules with the polymer on its surface. This effect is analyzed in the case of normal illumination of the film depending on the interfacial anchoring at the liquid crystal–polymer interface, the orientation of the optical axes of droplets, their concentration, sizes, anisometry, and polydispersity.
Crystallization and preliminary X-ray diffraction analysis of the peripheral light-harvesting complex LH2 from Marichromatium purpuratum.

Science.gov (United States)

Cranston, Laura J; Roszak, Aleksander W; Cogdell, Richard J

2014-06-01

LH2 from the purple photosynthetic bacterium Marichromatium (formerly known as Chromatium) purpuratum is an integral membrane pigment-protein complex that is involved in harvesting light energy and transferring it to the LH1-RC `core' complex. The purified LH2 complex was crystallized using the sitting-drop vapour-diffusion method at 294 K. The crystals diffracted to a resolution of 6 Å using synchrotron radiation and belonged to the tetragonal space group I4, with unit-cell parameters a=b=109.36, c=80.45 Å. The data appeared to be twinned, producing apparent diffraction symmetry I422. The tetragonal symmetry of the unit cell and diffraction for the crystals of the LH2 complex from this species reveal that this complex is an octamer.
Escherichia coli tRNAArg acceptor-stem isoacceptors: comparative crystallization and preliminary X-ray diffraction analysis

International Nuclear Information System (INIS)

Eichert, André; Schreiber, Angela; Fürste, Jens P.; Perbandt, Markus; Betzel, Christian; Erdmann, Volker A.; Förster, Charlotte

2009-01-01

Various E. coli tRNA Arg acceptor-stem microhelix isoacceptors have been crystallized and investigated by high-resolution X-ray diffraction analysis. The aminoacylation of tRNA is a crucial step in cellular protein biosynthesis. Recognition of the cognate tRNA by the correct aminoacyl-tRNA synthetase is ensured by tRNA identity elements. In tRNA Arg , the identity elements consist of the anticodon, parts of the D-loop and the discriminator base. The minor groove of the aminoacyl stem interacts with the arginyl-tRNA synthetase. As a consequence of the redundancy of the genetic code, six tRNA Arg isoacceptors exist. In the present work, three different Escherichia coli tRNA Arg acceptor-stem helices were crystallized. Two of them, the tRNA Arg microhelices RR-1660 and RR-1662, were examined by X-ray diffraction analysis and diffracted to 1.7 and 1.8 Å resolution, respectively. The tRNA Arg RR-1660 helix crystallized in space group P1, with unit-cell parameters a = 26.28, b = 28.92, c = 29.00 Å, α = 105.74, β = 99.01, γ = 97.44°, whereas the tRNA Arg RR-1662 helix crystallized in space group C2, with unit-cell parameters a = 33.18, b = 46.16, c = 26.04 Å, β = 101.50°
Thermal diffuse scattering in time-of-flight neutron diffraction studied on SBN single crystals

International Nuclear Information System (INIS)

Prokert, F.; Savenko, B.N.; Balagurov, A.M.

1994-01-01

At time-of-flight (TOF) diffractometer D N-2, installed at the pulsed reactor IBR-2 in Dubna, Sr x Ba 1-x Nb 2 O 6 mixed single crystals (SBN-x) of different compositions (0.50 < x< 0.75) were investigated between 15 and 773 K. The diffraction patterns were found to be strongly influenced by the thermal diffuse scattering (TDS). The appearance of the TDS from the long wavelength acoustic models of vibration in single crystals is characterized by the ratio of the velocity of sound to the velocity of neutron. Due to the nature of the TOF Laue diffraction technique used on D N-2, the TDS around Bragg peaks has rather a complex profile. An understanding of the TDS close to Bragg peaks is essential in allowing the extraction of the diffuse scattering occurring at the diffuse ferroelectric phase transition in SBN crystals. 11 refs.; 9 figs.; 1 tab. (author)
Low temperature and high pressure crystals of room temperature ionic liquid: N, N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate

International Nuclear Information System (INIS)

Abe, Hiroshi; Imai, Yusuke; Takekiyo, Takahiro; Yoshimura, Yukihiro; Hamaya, Nozomu

2014-01-01

Crystals of room temperature ionic liquid (RTIL) are obtained separately at low temperature or under high pressure. The RTIL is N, N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate, [DEME][BF 4 ]. At ambient pressure, low-temperature (LT) crystals appeared on slow cooling. By simultaneous X-ray diffraction and differential scanning calorimetry (DSC) measurements, metastable monoclinic and stable orthorhombic phases coexist in pure [DEME][BF 4 ]. Furthermore, the DSC thermal trace indicates that the metastable monoclinic phase was stabilized by adding water. In contrast, on compression process up to 7.6 GPa, crystallization is completely suppressed even upon slow compression. Direct observations using optical microscopy also support no crystal domain growth on compression process. High-pressure (HP) crystals at room temperature were seen only on decompression process, where two different kinds of crystals appeared subsequently. By crystal structure analysis, the LT crystal structures have no relation with the HP ones. Moreover, both metastable monoclinic phase at low temperature and higher pressure crystal has a folding molecular conformation and anti-parallel pairing of the [DEME] cation as the instability factors
ATLAS - analysis of time-of-flight diffraction data from liquid and amorphous samples

International Nuclear Information System (INIS)

Soper, A.K.; Howells, W.S.; Hannon, A.C.

1989-05-01

The purpose of this manual is to describe a package of data analysis routines which have been developed at the Rutherford Appleton Laboratory for the analysis of time-of-flight diffraction data from liquids, gases, and amorphous materials. There is no fundamental barrier to diffraction data being accurately analysed to structure factor or even pair correlation function within a very short time of the completion of the experiment. Section 1 describes the time-of-flight neutron diffraction experiment and looks at diffraction theory. Section 2 indicates the steps in data analysis of time-of-flight diffraction data and Section 3 gives details of how to run the procedures. (author)
Ultraviolet-pumped liquid-crystal dye-laser

International Nuclear Information System (INIS)

Bertolotti, M.; Sbrolli, L.; Scudieri, F.; Papa, T.

1981-01-01

The possibility offered by the orientation properties of liquid crystals as a matrix for dye lasers is shown. In particular, the linear polarization of emitted light can be changed by acting with an external magnetic field on the molecular nematic director. (author)
Dielectric relaxation spectra of liquid crystals in relation to molecular structure

International Nuclear Information System (INIS)

Wrobel, S.

1986-07-01

The dielectric spectra obtained for some members of two homologous series, i.e. for di-alkoxyazoxybenzenes and penthyl-alkoxythiobenzoates, are discussed qualitatively on the basis of the Nordio-Rigatti-Segre diffusion model. It is additionally assumed that the molecular reorientations take place about the principal axes of the inertia tensor. The distribution of correlation times, which is strongly temperature dependent in the vicinity of the clearing point, is interpreted as being caused by fluctuations of the principal axes frame which are due to conformation changes inside the end chains. The Bauer equation is used to describe both principal molecular reorientations, i.e. the reorientations about the long and short axis, observed in liquid crystalline structure by means of dielectric relaxation methods. The energies and entropies of activation have been computed for both principal reorientations. The differences between the high frequency limit of the dielectric permittivity and the refractive index squared of liquid crystals are explained in terms of two librational motions of the molecules observed by other experimental techniques, viz. far infra-red, Raman and inelastic neutron scattering spectroscopies, and found in this work on the basis of dielectrically measured energy barriers. It has been shown qualitatively that intramolecular libratory motions greatly effect the high frequency dielectric spectrum. Finally, molecular motions in liquid crystals are divided into two types: coherent and incoherent. 127 refs., 56 figs., 17 tabs. (author)

Crystallization and preliminary X-ray diffraction analysis of the MIF4G domain of DAP5

International Nuclear Information System (INIS)

Frank, Filipp; Virgili, Geneviève; Sonenberg, Nahum; Nagar, Bhushan

2009-01-01

The MIF4G domain of DAP5 was crystallized in two distinct crystal forms. Diffraction patterns have been analyzed and preliminary analysis, including molecular replacement, is presented here. Death-associated protein 5 (DAP5) is a member of the eIF4G family of scaffolding proteins that mediate cap-independent translation initiation by recruiting the translational machinery to internal ribosomal entry sites (IRESs) on mRNA. The MIF4G domain of DAP5 directly interacts with the eukaryotic initiation factors eIF4A and eIF3 and enhances the translation of several viral and cellular IRESs. Here, the crystallization and preliminary X-ray diffraction analysis of the MIF4G domain of DAP5 is presented
On the neutron diffraction in a crystal in the field of a standing laser wave

International Nuclear Information System (INIS)

Grigoryan, K.K.; Hayrapetyan, A.G.; Petrosyan, R.G.

2010-01-01

The possibility of high-energy neutron diffraction in a crystal is shown by applying the solution of time-dependent Schroedinger equation for a neutron in the field of a standing laser wave. The scattering picture is examined within the framework of non-stationary S-matrix theory, where the neutron-laser field interaction is considered exactly and the neutron-crystal interaction is considered as a perturbation described by Fermi pseudopotential (Farri representation). The neutron-crystal interaction is elastic, and the neutron-laser field interaction has both inelastic and elastic behaviors which results in the observation of an analogous to the Kapitza-Dirac effect for neutrons. The neutron scattering probability is calculated and the analysis of the results are adduced. Both inelastic and elastic diffraction conditions are obtained and the formation of a 'sublattice' is illustrated in the process of neutron-photon-phonon elastic interaction.
Preliminary morphological and X-ray diffraction studies of the crystals of the DNA cetyltrimethylammonium salt.

Science.gov (United States)

Osica, V D; Pyatigorskaya, T L; Polyvtsev, O F; Dembo, A T; Kliya, M O; Vasilchenko, V N; Verkin, B I; Sukharevskya, B Y

1977-04-01

Double-stranded DNA molecules (molecular weight 2.5 X 10(5) - 5 X 10(5) daltons) have been crystallized from water-salt solutions as cetyltrimethylammonium salts (CTA-DNA). Variation of crystallization conditions results in a production of different types of CTA-DNA crystals: spherulits, dendrites, needle-shaped and faceted rhombic crystals, the latter beeing up to 0.3 mm on a side. X-ray diffraction data indicate that DNA molecules in the crystals form a hexagonal lattice which parameters vary slightly with the morphological type of the crystal. Comparison of the melting curves of the DNA preparation before and after crystallization suggests that DNA molecules are partially fractionated in the course of crystallization. Crystals of the CTA-DNA-proflavine complex have also been obtained.
Calculation of Optical Parameters of Liquid Crystals

Science.gov (United States)

Kumar, A.

2007-12-01

Validation of a modified four-parameter model describing temperature effect on liquid crystal refractive indices is being reported in the present article. This model is based upon the Vuks equation. Experimental data of ordinary and extraordinary refractive indices for two liquid crystal samples MLC-9200-000 and MLC-6608 are used to validate the above-mentioned theoretical model. Using these experimental data, birefringence, order parameter, normalized polarizabilities, and the temperature gradient of refractive indices are determined. Two methods: directly using birefringence measurements and using Haller's extrapolation procedure are adopted for the determination of order parameter. Both approches of order parameter calculation are compared. The temperature dependences of all these parameters are discussed. A close agreement between theory and experiment is obtained.
NMR studies of macroscopic and microscopic properties of liquid crystals

International Nuclear Information System (INIS)

Hughes, J.R.

1998-03-01

The work presented is concerned with studies of orientational order in liquid crystals and the behaviour of certain mesophases. The experimental technique used in common with all the work is deuterium NMR spectroscopy. Much of the work involves studies of the orientational order of deuteriated solute molecules dissolved in liquid crystal solvents. Chapter 1 gives an introduction to liquid crystals followed by a quantitative description of orientational order. Deuterium NMR in liquid crystals is described and an outline of the molecular field theory behind the orientational order of a rigid, biaxial solute in a uniaxial mesophase is given. In Chapter 2 a novel type of mesophase induction is studied using NMR, where a solute induces up to two extra phases in a discotic mesogen depending on its concentration. The purpose of this work is to try to gain an understanding into the mechanism of the phase induction involved. Chapter 3 is concerned primarily with the macroscopic behaviour of the nematic phase formed by a semi-rigid main-chain polymer in solution. Of particular interest is the study of the reorientation of the monodomain, once the director has been rotated with respect to the magnetic field of the NMR spectrometer. A mesogen which has been claimed to exhibit a biaxial nematic phase is studied in Chapter 4, in order to determine the symmetry of the phase using NMR. Finally, Chapter 5 deals with the differing behaviour of a liquid crystal monomer and its dimer dissolved in common nematic solvents in order to determine whether this agrees with molecular field theory. (author)
Chemistry of Discotic Liquid Crystals From Monomers to Polymers

CERN Document Server

Kumar, Sandeep

2010-01-01

Compiling the scattered literature into a single seminal work, this book describes the basic design principles, synthesis, and mesomorphic properties of discotic liquid crystals. Of fundamental importance as models for the study of energy and charge migration in self-organized systems, discotic liquid crystals find functional application as one-dimensional conductors, photoconductors, light emitting diodes, photovoltaic solar cells, field-effect transistors, and gas sensors. This book highlights the scientific concepts behind the hierarchical self-assembly of these disc-shaped molecules alongs
Purification, crystallization and preliminary X-ray diffraction studies of UDP-N-acetylglucosamine pyrophosphorylase from Candida albicans

Energy Technology Data Exchange (ETDEWEB)

Maruyama, Daisuke; Nishitani, Yuichi; Nonaka, Tsuyoshi; Kita, Akiko [Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Fukami, Takaaki A.; Mio, Toshiyuki; Yamada-Okabe, Hisafumi [Kamakura Research Laboratory, Chugai Pharmaceutical Co. Ltd, 200 Kajiwara, Kamakura, Kanagawa 247-8530 (Japan); Yamada-Okabe, Toshiko [Department of Hygiene, School of Medicine, Yokohama City University, 3-9 Fukuura, Kanazawa, Yokohama 236-0004 (Japan); Miki, Kunio, E-mail: miki@kuchem.kyoto-u.ac.jp [Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); RIKEN SPring-8 Center at Harima Institute, Koto 1-1-1, Sayocho, Sayo-gun, Hyogo 679-5148 (Japan)

2006-12-01

UDP-N-acetylglucosamine pyrophosphorylase was purified and crystallized and X-ray diffraction data were collected to 2.3 Å resolution. UDP-N-acetylglucosamine pyrophosphorylase (UAP) is an essential enzyme in the synthesis of UDP-N-acetylglucosamine. UAP from Candida albicans was purified and crystallized by the sitting-drop vapour-diffusion method. The crystals of the substrate and product complexes both diffract X-rays to beyond 2.3 Å resolution using synchrotron radiation. The crystals of the substrate complex belong to the triclinic space group P1, with unit-cell parameters a = 47.77, b = 62.89, c = 90.60 Å, α = 90.01, β = 97.72, γ = 92.88°, whereas those of the product complex belong to the orthorhombic space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 61.95, b = 90.87, c = 94.88 Å.
Linear diffraction of light waves on periodically poled domain structures in lithium niobate crystals: collinear, isotropic, and anisotropic geometries

International Nuclear Information System (INIS)

Shandarov, S M; Mandel, A E; Akylbaev, T M; Borodin, M V; Savchenkov, E N; Smirnov, S V; Akhmatkhanov, A R; Shur, V Ya

2017-01-01

The possible variants of experimental observation of light diffraction on periodically poled domain structures (PPDS) in the lithium niobate crystal with 180-degree domain Y-walls are considered. We experimentally investigated isotropic and anisotropic diffraction of coherent light (λ = 655nm) on the PPDS with spatial period Λ = 8.79 μm produced by poling method in a LiNbO 3 : 5% MgO crystal. The central wavelength of irradiation experiencing a collinear diffraction on these PPDS is estimated as λ c = 455 nm. (paper)
Preliminary study of a phase transformation in insulin crystals using synchrotron-radiation Laue diffraction

Energy Technology Data Exchange (ETDEWEB)

Reynolds, C D; Stowell, B; Joshi, K K; Harding, M M; Maginn, S J; Dodson, G G

1988-10-01

Synchrotron-radiation Laue diffraction photographs have been recorded showing the transformation of single 4Zn insulin crystals (a=80.7 (1), c=37.6 (1) A, space group R3) to 2Zn insulin (a=82.5 (1), c=34.0 (1) A, space group R3). The transformation was brought about by changing the mother liquor in the capillary in which the crystal was mounted. Photographs were taken at 10 min intervals (exposure time 3 s) from 0.5 h after mounting. They showed initially a well ordered 4Zn insulin crystal (d/sub min/ ca 2.3 A), then a poorly ordered, sometimes multiple, crystal, and finally a 2Zn insulin crystal, about as well ordered as the initial crystal.
Crystal Structure, Vibrational Spectroscopy and ab Initio Density Functional Theory Calculations on the Ionic Liquid forming 1,1,3,3-Tetramethylguanidinium bis{(trifluoromethyl)sulfonyl}amide

DEFF Research Database (Denmark)

Berg, Rolf W.; Riisager, Anders; Nguyen van Buu, Olivier

2009-01-01

The salt 1,1,3,3-tetramethylguanidinium bis{(trifluoromethyl)sulfonyl}amide, [((CH3)(2)N)(2)C=NH2](+)[N(SO2-CF3)(2)](-) or [tmgH][NTf2], easily forms an ionic liquid with high SO2 absorbing capacity. The crystal structure of the salt was determined at 120(2) K by X-ray diffraction. The structure...
Crystallization and preliminary X-ray diffraction studies of the precursor protein of a thermostable variant of papain

International Nuclear Information System (INIS)

Roy, Sumana; Choudhury, Debi; Chakrabarti, Chandana; Biswas, Sampa; Dattagupta, J. K.

2011-01-01

The crystallization of the precursor of a thermostable variant of papain and the collection of diffraction data to 2.6 Å resolution are reported. The crystallization of a recombinant thermostable variant of pro-papain has been carried out. The mutant pro-enzyme was expressed in Escherichia coli as inclusion bodies, refolded, purified and crystallized. The crystals belonged to space group P2 1 , with unit-cell parameters a = 42.9, b = 74.8, c = 116.5 Å, β = 93.0°, and diffracted to 2.6 Å resolution using synchrotron radiation. Assuming the presence of two molecules in the asymmetric unit, the calculated Matthews coefficient is 2.28 Å 3 Da −1 , corresponding to a solvent content of 46%. Initial attempts to solve the structure using molecular-replacement techniques were successful
Crystallization and diffraction properties of the Fab fragment of 3B5H10, an antibody specific for disease-causing polyglutamine stretches

Energy Technology Data Exchange (ETDEWEB)

Peters-Libeu, Clare; Newhouse, Yvonne; Krishnan, Preethi; Cheung, Kenneth; Brooks, Elizabeth [Gladstone Institute of Neurological Disease, 1650 Owens Street, San Francisco, CA 94158 (United States); Weisgraber, Karl [Gladstone Institute of Neurological Disease, 1650 Owens Street, San Francisco, CA 94158 (United States); Department of Pathology, University of California, San Francisco, CA 94143 (United States); Finkbeiner, Steven, E-mail: sfinkbeiner@gladstone.ucsf.edu [Gladstone Institute of Neurological Disease, 1650 Owens Street, San Francisco, CA 94158 (United States); Departments of Neurology, Physiology and Neuroscience and Biomedical Sciences Program, University of California, San Francisco, CA 94143 (United States)

2005-12-01

Optimization of crystallization conditions and cryoprotectants decreased the anisotropy of the diffraction obtained from 3B5H10 Fab crystals. Dehydration improved the resolution of cryoprotected 3B5H10 crystals from 2.6 to 1.9 Å, but changed the space group of the crystals from P2{sub 1}2{sub 1}2 to P2{sub 1}. Because it binds soluble forms of proteins with disease-associated polyglutamine expansions, the antibody 3B5H10 is a powerful tool for studying polyglutamine-related diseases. Crystals of the 3B5H10 Fab (47 kDa) were obtained by vapor diffusion at room temperature from PEG 3350. However, the initial crystals gave highly anisotropic diffraction patterns. After optimization of the crystallization conditions and cryoprotectants, a nearly isotropic diffraction pattern at 2.6 Å resolution was achieved for crystals with unit-cell parameters a = 133.26, b = 79.52, c = 41.49 Å and space group P2{sub 1}2{sub 1}2. Dehydrated crystals diffracted isotropically to 1.9 Å with unit-cell parameters a = 123.65, b = 78.25, c = 42.26 Å, β = 90.3° and space group P2{sub 1}.
Diffractive optics and nanophotonics resolution below the diffraction limit

CERN Document Server

Minin, Igor

2016-01-01

In this book the authors present several examples of techniques used to overcome the Abby diffraction limit using flat and 3D diffractive optical elements, photonic crystal lenses, photonic jets, and surface plasmon diffractive optics. The structures discussed can be used in the microwave and THz range and also as scaled models for optical frequencies. Such nano-optical microlenses can be integrated, for example, into existing semiconductor heterostructure platforms for next-generation optoelectronic applications. Chapter 1 considers flat diffractive lenses and innovative 3D radiating structures including a conical millimeter-wave Fresnel zone plate (FZP) lens proposed for subwavelength focusing. In chapter 2 the subwavelength focusing properties of diffractive photonic crystal lenses are considered and it is shown that at least three different types of photonic crystal lens are possible. With the aim of achieving subwavelength focusing, in chapter 3 an alternative mechanism to produce photonic jets at Tera...
Bond orientational ordering in a metastable supercooled liquid: a shadow of crystallization and liquid–liquid transition

International Nuclear Information System (INIS)

Tanaka, Hajime

2010-01-01

It is widely believed that a liquid state can be characterized by a single order parameter, density, and that a transition from a liquid to solid can be described by density ordering (translational ordering). For example, this type of theory has had great success in describing the phase behaviour of hard spheres. However, there are some features that cannot be captured by such theories. For example, hard spheres crystallize into either hcp or fcc structures, without a tendency of bcc ordering which is expected by the Alexander–McTague theory based on the Landau-type free energy of the density order parameter. We also found hcp-like bond orientational ordering in a metastable supercooled liquid, which promotes nucleation of hcp crystals. Furthermore, theories based on the single order parameter cannot explain water-like thermodynamic and kinetic anomalies of a liquid and liquid–liquid transition in a single-component liquid. Based on these facts, we argue that we need an additional order parameter to describe a liquid state. It is bond orientational order, which is induced by dense packing in hard spheres or by directional bonding in molecular and atomic liquids. Bond orientational order is intrinsically of local nature, unlike translational order which is of global nature. This feature plays a unique role in crystallization and quasicrystal formation. We also reveal that bond orientational ordering is a cause of dynamic heterogeneity near a glass transition and is linked to slow dynamics. In relation to this, we note that, for describing the structuring of a highly disordered liquid, we need a structural signature of low configurational entropy, which is more general than bond orientational order. Finally, the water-like anomaly and liquid–liquid transition can be explained by bond orientational ordering due to hydrogen or covalent bonding and its cooperativity, respectively. So we argue that bond orientational ordering is a key to the physical understanding
FDTD modelling of gold nanoparticle pairs in a nematic liquid crystal cell

Energy Technology Data Exchange (ETDEWEB)

Dridi, Montacer; Vial, Alexandre, E-mail: montacer.dridi@utt.f, E-mail: alexandre.vial@utt.f [Laboratoire de Nanotechnologie et d' Instrumentation Optique, Institut Charles Delaunay, UMR CNRS 6279, Universite de Technologie de Troyes, 12, rue Marie Curie, BP 2060, 10010 Troyes Cedex (France)

2010-10-20

In this paper, we numerically investigate a grating of gold dimer in a nematic liquid crystal (LC) media. We show that the plasmon resonance exhibits a high sensitivity to the distance between nanoparticles for all orientations of molecules of LCs. The behaviour of plasmon resonance can be described by a simple function called compressed hyperbola that overcomes the limitation of describing this behaviour by the well-known exponential function. Also we show that the orientation of the optical axis leads to an important spectral tunability. We demonstrate then that for certain orientations of the optical axis, we can induce a diffraction coupling featuring an additional narrow resonance peak. Finally near-field properties of the structure are investigated, and we demonstrate that by rotating the director we can control the local field enhancement.
The opto-thermal effect on encapsulated cholesteric liquid crystals

Science.gov (United States)

Liu, Yu-Sung; Lin, Hui-Chi; Yang, Kin-Min

2017-12-01

In this study, we implemented a micro-encapsulated CLC electronic paper that is optically addressed and electrically erasable. The mechanism that forms spot diameters on the CLC films is discussed and verified through various experimental parameters, including the thickness of CLCs and Poly(2,3-dihydrothieno-1,4-dioxin)-poly(styrenesulfonate) (PEDOT:PSS), pump intensity, and pumping time. The opto-thermal effect, brought on by the PEDOT:PSS absorbing layer, causes the spot diameters on the cholesteric liquid crystal thin films to vary. According to our results, the spot diameter is larger for a sample with a thinner cholesteric liquid crystal layer with the same excitation conditions and same thickness of the PEDOT layer. The spot diameter is also larger for a sample with a thicker PEDOT under the same excitation conditions and same thickness of the cholesteric liquid crystal layer. We proposed a simple heat-conducting model to explain the experimental results, which qualitatively agree with this theoretical model.
Crystal structure determination from powder diffraction data of the coumarin vanillin chalcone

Czech Academy of Sciences Publication Activity Database

Ghouili, A.; Rohlíček, Jan; Ayed, T.B.; Hassen, R.B.

2014-01-01

Roč. 29, č. 4 (2014), s. 361-365 ISSN 0885-7156 Grant - others:AV ČR(CZ) Praemium Academiae Institutional support: RVO:68378271 Keywords : chalcone * absorption spectra * powder diffraction * crystal structure determination * coumarin derivatives Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.636, year: 2014
Ionic diffusion and salt dissociation conditions of lithium liquid crystal electrolytes.

Science.gov (United States)

Saito, Yuria; Hirai, Kenichi; Murata, Shuuhei; Kishii, Yutaka; Kii, Keisuke; Yoshio, Masafumi; Kato, Takashi

2005-06-16

Salt dissociation conditions and dynamic properties of ionic species in liquid crystal electrolytes of lithium were investigated by a combination of NMR spectra and diffusion coefficient estimations using the pulsed gradient spin-echo NMR techniques. Activation energies of diffusion (Ea) of ionic species changed with the phase transition of the electrolyte. That is, Ea of the nematic phase was lower than that of the isotropic phase. This indicates that the aligned liquid crystal molecules prepared efficient conduction pathways for migration of ionic species. The dissociation degree of the salt was lower compared with those of the conventional electrolyte solutions and polymer gel electrolytes. This is attributed to the low concentration of polar sites, which attract the dissolved salt and promote salt dissociation, on the liquid crystal molecules. Furthermore, motional restriction of the molecules due to high viscosity and molecular oriented configuration in the nematic phase caused inefficient attraction of the sites for the salt. With a decreased dissolved salt concentration of the liquid crystal electrolyte, salt dissociation proceeded, and two diffusion components attributed to the ion and ion pair were detected independently. This means that the exchange rate between the ion and the ion pair is fairly slow once the salt is dissociated in the liquid crystal electrolytes due to the low motility of the medium molecules that initiate salt dissociation.
Light Diffraction by Large Amplitude Ultrasonic Waves in Liquids

Science.gov (United States)

Adler, Laszlo; Cantrell, John H.; Yost, William T.

2016-01-01

Light diffraction from ultrasound, which can be used to investigate nonlinear acoustic phenomena in liquids, is reported for wave amplitudes larger than that typically reported in the literature. Large amplitude waves result in waveform distortion due to the nonlinearity of the medium that generates harmonics and produces asymmetries in the light diffraction pattern. For standing waves with amplitudes above a threshold value, subharmonics are generated in addition to the harmonics and produce additional diffraction orders of the incident light. With increasing drive amplitude above the threshold a cascade of period-doubling subharmonics are generated, terminating in a region characterized by a random, incoherent (chaotic) diffraction pattern. To explain the experimental results a toy model is introduced, which is derived from traveling wave solutions of the nonlinear wave equation corresponding to the fundamental and second harmonic standing waves. The toy model reduces the nonlinear partial differential equation to a mathematically more tractable nonlinear ordinary differential equation. The model predicts the experimentally observed cascade of period-doubling subharmonics terminating in chaos that occurs with increasing drive amplitudes above the threshold value. The calculated threshold amplitude is consistent with the value estimated from the experimental data.
Effects of spin orbital coupling on atomic and electronic structures in Al{sub 2}Cu and Al{sub 2}Au crystal and liquid phases via ab initio molecular dynamics simulations

Energy Technology Data Exchange (ETDEWEB)

Wang, Y. [International Center for New-Structured Materials (ICNSM), Laboratory of New-Structured Materials, State Key Laboratory of Silicon Materials, and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Lu, Y.H., E-mail: luyh@zju.edu.cn [International Center for New-Structured Materials (ICNSM), Laboratory of New-Structured Materials, State Key Laboratory of Silicon Materials, and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Wang, X.D.; Cao, Q.P. [International Center for New-Structured Materials (ICNSM), Laboratory of New-Structured Materials, State Key Laboratory of Silicon Materials, and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Zhang, D.X. [State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027 (China); Jiang, J.Z., E-mail: jiangjz@zju.edu.cn [International Center for New-Structured Materials (ICNSM), Laboratory of New-Structured Materials, State Key Laboratory of Silicon Materials, and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

2014-11-15

Highlights: • The SOC effect affects the cohesion energy of crystal phase. • The effect of SOC was reduced due to random local atomic structures in liquids. • The local geometrical structures also affect the melting points. • Both SOC effect and local atomic structures are important for melting point difference. - Abstract: The origin of different melting points between Al{sub 2}Cu and Al{sub 2}Au has been studied using ab initio molecular dynamics simulations. Cohesive energy, electronic structures and structure information of both crystal and liquid phases have been analyzed. It is found that spin orbital coupling (SOC) plays an important role on the cohesive energy of crystal phase, consistent with the different melting points of these two alloys. Whereas, it seems that SOC has no effect on the formation energy and structure of liquid phase. Possible mechanism of reduced SOC effect at liquid phase is proposed. Our results are helpful to understand the glass formation ability difference between Al{sub 2}Cu and Al{sub 2}Au.

Functional Smart Dispersed Liquid Crystals for Nano- and Biophotonic Applications: Nanoparticles-Assisted Optical Bioimaging

Directory of Open Access Journals (Sweden)

N. V. Kamanina

2016-01-01

Full Text Available Functional nematic liquid crystal structures doped with nano- and bioobjects have been investigated. The self-assembling features and the photorefractive parameters of the structured liquid crystals have been comparatively studied via microscopy and laser techniques. Fullerene, quantum dots, carbon nanotubes, DNA, and erythrocytes have been considered as the effective nano- and biosensitizers of the LC mesophase. The holographic recording technique based on four-wave mixing of the laser beams has been used to investigate the laser-induced change of the refractive index in the nano- and bioobjects-doped liquid crystal cells. The special accent has been given to novel nanostructured relief with vertically aligned carbon nanotubes at the interface: solid substrate-liquid crystal mesophase. It has been shown that this nanostructured relief influences the orienting ability of the liquid crystal molecules with good advantage. As a result, it provokes the orientation of the DNA. The modified functional liquid crystal materials have been proposed as the perspective systems for both the photonics and biology as well as the medical applications.
Evanescent Field Enhancement in Liquid Crystal Optical Fibers: A Field Characteristics Based Analysis

Directory of Open Access Journals (Sweden)

P. K. Choudhury

2013-01-01

Full Text Available The paper presents the analysis of the electromagnetic wave propagation through liquid crystal optical fibers (LCOFs of two different types—conventional guides loaded with liquid crystals (addressed as LCOFs and those with additional twists due to conducting helical windings (addressed as HCLCOFs. More precisely, the three-layer optical waveguide structures are considered along with its outermost region being loaded with radially anisotropic liquid crystal material and the inner regions being made of usual silica, as used in conventional optical fibers. In addition to that, LCOF with twists introduced in the form of conducting helical windings at the interface of the silica core and the liquid crystal clad is also taken into account. Emphasis has been put on the power confinements by the lower-order TE modes sustained in the different sections of the LCOF structure. The results demonstrate useful applications of these guides in integrated optics as the power sustained in the liquid crystal section by the excited TE modes remains very high. In the case of twisted clad liquid crystal guides, descriptions are limited to the nature of dispersion relation only under the TE mode excitation, and corresponding to the cases of helix orientations being parallel and perpendicular to the optical axis.
Programmable liquid crystal waveplate polarization gratings as elements for polarimetric and interference applications

Science.gov (United States)

Moreno, I.; Davis, J. A.

2010-06-01

We review the use of a parallel aligned nematic liquid crystal spatial light modulator as a very useful and flexible device for polarimetric and interferometric applications. The device acts as a programmable pixelated waveplate, and the encoding of a linear grating permits its use as a polarization beam splitter. When a grating with a reduced period is encoded, the diffracted beams are spatially separated and the device can be used for polarimetric analysis. On the contrary when a large period grating is displayed, the beams are not spatially separated, and they are useful to realize a common path interferometric system with polarization sensitivity. The flexibility offered by the programmability of the display allows non-conventional uses, including the analysis of light beams with structured spatial polarizations.
How to distinguish perfect quasi-crystals from twins and other structures using diffraction experiments?

International Nuclear Information System (INIS)

Wolny, J.

1992-01-01

Performing diffraction experiments for various lengths of coherent scattering and using the scaling of peak intensities on a number of atoms one can experimentally distinguish quasi-crystals from the other structures (e.g. twins or random). For perfect quasi-crystals peak intensities scale as N 2 , for other structures this scaling depends on concentration of atoms, behaving critical for Penrose concentration. 3 figs., 8 refs. (author)
Thermotropic liquid crystals recent advances

CERN Document Server

Ramamoorthy, Ayyalusamy

2007-01-01

This book covers developments in the field of thermotropic liquid crystals and their functional importance. It also presents advances related to different sub-areas pertinent to this interdisciplinary area of research. This text brings together research from synthetic scientists and spectroscopists and attempts to bridge the gaps between these areas. New physical techniques that are powerful in characterizing these materials are discussed.
Purification, crystallization and preliminary X-ray diffraction analysis of the HMG domain of Sox17 in complex with DNA

International Nuclear Information System (INIS)

Ng, Calista Keow Leng; Palasingam, Paaventhan; Venkatachalam, Rajakannan; Baburajendran, Nithya; Cheng, Jason; Jauch, Ralf; Kolatkar, Prasanna R.

2008-01-01

Crystals of the Sox17 HMG domain bound to LAMA1 enhancer DNA-element crystals that diffracted to 2.75 Å resolution were obtained. Sox17 is a member of the SRY-related high-mobility group (HMG) of transcription factors that have been shown to direct endodermal differentiation in early mammalian development. The LAMA1 gene encoding the α-chain of laminin-1 has been reported to be directly bound and regulated by Sox17. This paper describes the details of initial crystallization attempts with the HMG domain of mouse Sox17 (mSox17-HMG) with a 16-mer DNA element derived from the LAMA1 enhancer and optimization strategies to obtain a better diffracting crystal. The best diffracting crystal was obtained in a condition containing 0.1 M Tris–HCl pH 7.4, 0.2 M MgCl 2 , 30% PEG 3350 using the hanging-drop vapour-diffusion method. A highly redundant in-house data set was collected to 2.75 Å resolution with 99% completeness. The presence of the mSox17-HMG–DNA complex within the crystals was confirmed and Matthews analysis indicated the presence of one complex per asymmetric unit
Crystallization and preliminary X-ray diffraction analysis of protein 14 from Sulfolobus islandicus filamentous virus (SIFV)

International Nuclear Information System (INIS)

Goulet, Adeline; Spinelli, Silvia; Campanacci, Valérie; Porciero, Sophie; Blangy, Stéphanie; Garrett, Roger A.; Tilbeurgh, Herman van; Leulliot, Nicolas; Basta, Tamara; Prangishvili, David; Cambillau, Christian

2006-01-01

Crystals of S. islandicus filamentous virus (SIFV) protein 14 have been grown at 293 K. Crystals belong to space group P6 2 22 or P6 4 22 and diffract to a resolution of 2.95 Å. A large-scale programme has been embarked upon aiming towards the structural determination of conserved proteins from viruses infecting hyperthermophilic archaea. Here, the crystallization of protein 14 from the archaeal virus SIFV is reported. This protein, which contains 111 residues (MW 13 465 Da), was cloned and expressed in Escherichia coli with an N-terminal His 6 tag and purified to homogeneity. The tag was subsequently cleaved and the protein was crystallized using PEG 1000 or PEG 4000 as a precipitant. Large crystals were obtained of the native and the selenomethionine-labelled protein using sitting drops of 100–300 nl. Crystals belong to space group P6 2 22 or P6 4 22, with unit-cell parameters a = b = 68.1, c = 132.4 Å. Diffraction data were collected to a maximum acceptable resolution of 2.95 and 3.20 Å for the SeMet-labelled and native protein, respectively
Interpretation of small-angle diffraction experiments on opal-like photonic crystals

Science.gov (United States)

Marlow, F.; Muldarisnur, M.; Sharifi, P.; Zabel, H.

2011-08-01

Comprehensive structural information on artificial opals involving the deviations from the strongly dominating face-centered cubic structure is still missing. Recent structure investigations with neutrons and synchrotron sources have shown a high degree of order but also a number of unexpected scattering features. Here, we point out that the exclusion of the allowed 002-type diffraction peaks by a small atomic form factor is not obvious and that surface scattering has to be included as a possible source for the diffraction peaks. Our neutron diffraction data indicate that surface scattering is the main reason for the smallest-angle peaks in the diffraction patterns.
Ibuprofen-Amino Acids Co-Crystal Screening Via Co-Grinding Methods

Directory of Open Access Journals (Sweden)

Othman Muhamad Fitri

2016-01-01

Full Text Available The importance of pharmaceutical co-crystals now has been recognized in order to improve the research and development in pharmaceutical industries. Low solubility of active pharmaceutical ingredient (API has led to the growth of new pharmaceutical co-crystals formation as it enhances the physicochemical properties of the API. In this works, preparation of new co-crystal formation between ibuprofen (IBP with selected amino acid compounds were performed by using dry grinding and liquid assisted grinding (LAG techniques. Ibuprofen (IBP was selected as the API meanwhile glycine (GLY, L-alanine (ALA and L-proline (PRO were selected as co-crystal former (CCF agents. The products of IBP-co-former from grinding experiments for the formation of co-crystals were characterized and verified using X-Ray Powder Diffraction (XRPD, Differential Scanning Calorimetry (DSC and Fourier Transform Infra-Red Spectroscopy (FTIR. The finding reveals that the IBP-PRO co-crystals have successfully formed. For IBP-PRO system, new crystalline peaks from XRPD were recorded at 2θ values of 4.374°, 5.436° and 10.944° from dry grinding technique and 4.41°, 5.436° and 10.962° for liquid assisted grinding (LAG technique. A new melting point of 257.49 °C was discovered for IBP-ALA indicates the possibility of co-crystals formation. On the other hand, the analysis for IBP-GLY shows that no co-crystals formed in the system.
The application of X-ray, γ-ray and neutron diffraction to the characterization of single crystal perfection

International Nuclear Information System (INIS)

Freund, A.; Schneider, J.R.

1976-01-01

The work is divided into the following three chapters: 1) diffraction by perfect and imperfect crystals, 2) experimental apparatus (describing gamma ray, X-ray and neutron diffractometers), 3) application of diffraction methods to the development of neutron monochromators. (WBU) [de
Synthesis of carbonated hydroxyapatite nanorods in liquid crystals

Directory of Open Access Journals (Sweden)

Daniella Dias Palombino de Campos

2009-09-01

Full Text Available Syntheses of calcium phosphate nanoparticles, carried out in systems formed from surfactant, oil and water, have resulted in materials with promising possibilities for application. The calcium phosphate particles were synthesized using two different liquid crystals, formed from RenexTM, cyclohexane and a salts solution. The morphology of the nanoparticles synthesized in the liquid crystals is similar to that of hydroxyapatite particles that form bone mineral, where collagen fibers connect these particles so as to form a composite. Therefore, the synthesis of calcium phosphate nanoparticles in the systems used in this work can advance current understanding of mineralization processes that result in the formation of bone mineral.
Phasor analysis of binary diffraction gratings with different fill factors

International Nuclear Information System (INIS)

MartInez, Antonio; Sanchez-Lopez, Ma del Mar; Moreno, Ignacio

2007-01-01

In this work, we present a simple analysis of binary diffraction gratings with different slit widths relative to the grating period. The analysis is based on a simple phasor technique directly derived from the Huygens principle. By introducing a slit phasor and a grating phasor, the intensity of the diffracted orders and the grating's resolving power can be easily obtained without applying the usual Fourier transform operations required for these calculations. The proposed phasor technique is mathematically equivalent to the Fourier transform calculation of the diffraction order amplitude, and it can be useful to explain binary diffraction gratings in a simple manner in introductory physics courses. This theoretical analysis is illustrated with experimental results using a liquid crystal device to display diffraction gratings with different fill factors
Liquid Crystal Airborne Display

Science.gov (United States)

1977-08-01

Cum.nings, J. P., et al., Properties and Limitations oe Liquid Crystals for Aircraft Displays, Honeywell Corporate Researc ."I Center, Final Report HR-72...basic module could be used to build displays for both the commercial and military! 157- marhecs, and so would establi sh a broad and sizable market ... market for the display becomes a reality; therein lies, f TABLE 16 THE COURSE OF FUTURE DISPLAY DEVELOPMENT Today 1976-77 1980 1985 Display Size 2" 1 3.2
Crystallization and preliminary X-ray diffraction analysis of PAT, an acetyltransferase from Sulfolobus solfataricus

International Nuclear Information System (INIS)

Cho, Ching-Chang; Luo, Ching-Wei; Hsu, Chun-Hua

2008-01-01

PAT, an acetyltransferase from the archaeon S. solfataricus that specifically acetylates the chromatin protein Alba, was expressed, purified and crystallized. PAT is an acetyltransferase from the archaeon Sulfolobus solfataricus that specifically acetylates the chromatin protein Alba. The enzyme was expressed, purified and subsequently crystallized using the sitting-drop vapour-diffusion technique. Native diffraction data were collected to 1.70 Å resolution on the BL13C1 beamline of NSRRC from a flash-frozen crystal at 100 K. The crystals belonged to space group P2 1 2 1 2 1 , with unit-cell parameters a = 44.30, b = 46.59, c = 68.39 Å
The finite-size effect in thin liquid crystal systems

Science.gov (United States)

Śliwa, I.

2018-05-01

Effects of surface ordering in liquid crystal systems confined between cell plates are of great theoretical and experimental interest. Liquid crystals introduced in thin cells are known to be strongly stabilized and ordered by cell plates. We introduce a new theoretical method for analyzing the effect of surfaces on local molecular ordering in thin liquid crystal systems with planar geometry of the smectic layers. Our results show that, due to the interplay between pair long-range intermolecular forces and nonlocal, relatively short-range, surface interactions, both orientational and translational orders of liquid crystal molecules across confining cells are very complex. In particular, it is demonstrated that the SmA, nematic, and isotropic phases can coexist. The phase transitions from SmA to nematic, as well as from nematic to isotropic phases, occur not simultaneously in the whole volume of the system but begin to appear locally in some regions of the LC sample. Phase transition temperatures are demonstrated to be strongly affected by the thickness of the LC system. The dependence of the corresponding shifts of phase transition temperatures on the layer number is shown to exhibit a power law character. This new type of scaling behavior is concerned with the coexistence of local phases in finite systems. The influence of a specific character of interactions of molecules with surfaces and other molecules on values of the resulting critical exponents is also analyzed.
Chiral-nematic liquid crystals as one dimensional photonic materials in optical sensors

NARCIS (Netherlands)

Mulder, D.J.; Schenning, A.P.H.J.; Bastiaansen, C.W.M.

2014-01-01

Current developments in the field of thermotropic chiral-nematic liquid crystals as sensors are discussed. These one dimensional photonic materials are based on low molecular weight liquid crystals and chiral-nematic polymeric networks. For both low molecular weight LCs and polymer networks,
Crystallization and preliminary X-ray diffraction analysis of human endoplasmic reticulum aminopeptidase 2

International Nuclear Information System (INIS)

Ascher, David B.; Polekhina, Galina; Parker, Michael W.

2012-01-01

The luminal domain of human endoplasmic reticulum aminopeptidase 2 has been expressed, purified and crystallized. The crystals belonged to the orthorhombic space group P2 1 2 1 2 and diffracted anisotropically to 3.3 Å resolution in the best direction on an in-house source. Endoplasmic reticulum aminopeptidase 2 (ERAP2) is a critical enzyme involved in the final processing of MHC class I antigens. Peptide trimming by ERAP2 and the other members of the oxytocinase subfamily is essential to customize longer precursor peptides in order to fit them to the correct length required for presentation on major histocompatibility complex class I molecules. While recent structures of ERAP1 have provided an understanding of the ‘molecular-ruler’ mechanism of substrate selection, little is known about the complementary activities of its homologue ERAP2 despite their sharing 49% sequence identity. In order to gain insights into the structure–function relationship of the oxytocinase subfamily, and in particular ERAP2, the luminal region of human ERAP2 has been crystallized in the presence of the inhibitor bestatin. The crystals belonged to an orthorhombic space group and diffracted anisotropically to 3.3 Å resolution in the best direction on an in-house X-ray source. A molecular-replacement solution suggested that the enzyme has adopted the closed state as has been observed in other inhibitor-bound aminopeptidase structures
Thermal tunability of photonic bandgaps in liquid crystal infiltrated microstructured polymer optical fibers

DEFF Research Database (Denmark)

Yuan, Scott Wu; Wei, Lei; Alkeskjold, Thomas Tanggaard

2009-01-01

We demonstrate the photonic bandgap effect and the thermal tunability of bandgaps in microstructured polymer optical fibers infiltrated with liquid crystal. Two liquid crystals with opposite sign of the temperature gradient of the ordinary refractive index (E7 and MDA-00- 1444) are used to demons......We demonstrate the photonic bandgap effect and the thermal tunability of bandgaps in microstructured polymer optical fibers infiltrated with liquid crystal. Two liquid crystals with opposite sign of the temperature gradient of the ordinary refractive index (E7 and MDA-00- 1444) are used...... to demonstrate that both signs of the thermal tunability of the bandgaps are possible. The useful bandgaps are ultimately bounded to the visible range by the transparency window of the polymer....
Thermal Analysis, Mechanical and Rheological Behaviour of Melt Manufactured Polyethylene/Liquid Crystal Polymer Blends

Directory of Open Access Journals (Sweden)

Ilze ELKSNITE

2011-07-01

Full Text Available Modification of properties of conventional thermoplastics with thermotropic liquid crystal polymers, from one hand, allows decrease their viscosities, substantially facilitating processing conditions, and, from another hand, allows increase their exploitation properties. Orientation of the labile structure of liquid crystal polymer in extrusion or injection moulding causes specific reinforcement (so-called self-reinforcement to occur in the blends containing liquid crystal polymer. Up to now the effect of self-reinforcement is mostly investigated in the blends, containing considerable amount of liquid crystal polymer. In this research the effect of minor amounts of liquid crystalline co-polyester modifier on the properties of polyethylene is investigated. Various compositions of laboratory synthesized hydroxybenzoic acid /polyethylene terephtalate copolymer containing polyethylene composites have been manufactured by thermoplastic blending. It has been observed that 1 modulus of elasticity, yield strength and ultimate strength increase with raising the content of liquid crystalline modifier; 2 void content in the investigated polyethylene/liquid crystal copolymer composites is not greater that 1 %; 3 addition of liquid crystalline co-polyester modifier improves arrangement of PE crystalline phase.http://dx.doi.org/10.5755/j01.ms.17.2.483
Fluorinert as a pressure-transmitting medium for high-pressure diffraction studies

International Nuclear Information System (INIS)

Varga, Tamas; Wilkinson, Angus P.; Angel, Ross J.

2003-01-01

Fluorinert is a liquid pressure-transmitting medium that is widely used in high-pressure diffraction work. A systematic study of five different fluorinerts was carried out using single-crystal x-ray diffraction in a diamond-anvil cell in order to determine the pressure range over which they provide a hydrostatic stress state to the sample. It was found that none of the fluorinerts studied can be considered hydrostatic above 1.2 GPa, a lower pressure than reported previously

Shrink, twist, ripple and melt: Studies of frustrated liquid crystals

Science.gov (United States)

Fernsler, Jonathan G.

Complex structures can arise out of a simple system with more than one competing influence on its behavior. The protypical example of this is the two-dimensional triangular lattice Ising model. The ferromagnetic model has two simple degenerate ground states of all spins up or down, but the antiferromagnetic model is a frustrated system. Its geometry does not allow satisfaction of the antiferro condition everywhere, which produces complex ordered structures with dimerization of the spins [1]. Without frustration, the complex structures and phase behavior are lost. All of the topics discussed in this thesis concern smectic liquid crystals. Liquid crystals are perhaps uniquely adept at manifesting frustrated phases. Their combination of periodicity in one or more dimensions allows ordered structures, yet their fluid nature in remaining dimensions allows creation of defects and extraordinarily complex structures in ways that a normal crystal could not tolerate. Liquid crystals contain a huge menagerie of frustrated phases and effects including the polarization modulated [2], vortex lattice [3], twist grain boundary [4], and blue [5] phases, as well as frustrated structures such as cholesteric or SmC* helix unwinding [6], defect lattices in thin films [7], and bend melted grain boundary defects [8], arising from boundary conditions and field effects. In this thesis, we study four liquid crystal systems that show unusual phase behavior or complex structures, deriving from the effects of frustration. Frustration, despite some human prejudices against the word, leaves nature all the more interesting and beautiful.
The CCP14 for single crystal and powder diffraction

International Nuclear Information System (INIS)

Cranswick, L.M.D.

1999-01-01

Full text: The Collaborative Computation Project Number 14 for Single Crystal and Powder Diffraction (CCP14) is continuing in its objective to provide freely available software and resources for the powder diffraction and crystallographic community. Using the Internet and World Wide Web, we are presently compiling software and web resources, creating tutorials and help files. It also endeavours to encourage and provide resources to assist program authors with developing their software. The CCP14 presently has its web-site at and a mirror at (at CSIRO, Melbourne, Australia). Auto web-mirroring is being implemented to allow users to obtain software and access to resources in a more time effective manner. For people in countries isolated from the Internet, the CCP14 on CD-ROM can be snail mailed on request. This is in the form of a Virtual World Wide Web/Virtual Internet; in the same vein as the existing Crystallographic Nexus CD-ROM. Copyright (1999) Australian X-ray Analytical Association Inc
Neutron magnetic multiple diffraction in a natural magnetite crystal

International Nuclear Information System (INIS)

Mazzocchi, V.L.; Parente, C.B.R.

1988-09-01

Neutron multiple diffraction has been employed in the study of the magnetism in magnetite (Fe 3 O 4 ). Magnetite has a crystallographic structure of an inverted spinel with tetrahedral A sites occupied solely by trivalent Fe 3+ ions and octahedral B sites occupied both by divalent Fe 2+ ions and the remaining Fe 3+ ions in random distribution. At room temperature magnetite is a Neel A-B ferrimagnet where the ions on the A, B sites are coupled antiferromagneticaly. This coupling disappears at T sup c approx. or approx.= 580 0 C. Employing a natural single crystal of magnetite experimental neutron multiple diffraction patterns were obtained for the primary reflection 111 at room temperature and 703 0 C. This reflection is almost entirely magnetic in origin resulting in 'Aufhellung' patterns below T c and mixed 'Aufhellung-Umweganregung' patterns above T c . Theoretical patterns were calculated employing the iterative method for the approximation of intensities by a Taylor series and compared to the experimental results. (author) [pt
A Microwave Tunable Bandpass Filter for Liquid Crystal Applications

Science.gov (United States)

Cao, Weiping; Jiang, Di; Liu, Yupeng; Yang, Yuanwang; Gan, Baichuan

2017-07-01

In this paper, a novel microwave continuously tunable band-pass filter, based on nematic liquid crystals (LCs), is proposed. It uses liquid crystal (LC) as the electro-optic material to mainly realize frequency shift at microwave band by changing the dielectric anisotropy, when applying the bias voltage. According to simulation results, it achieves 840 MHz offset. Comparing to the existing tunable filter, it has many advantages, such as continuously tunable, miniaturization, low processing costs, low tuning voltage, etc. Thus, it has shown great potentials in frequency domain and practical applications in modern communication.
Flexoelectricity in an oxadiazole bent-core nematic liquid crystal

OpenAIRE

Kaur, Sarabjot; Panov, V. P.; Greco, C.; Ferrarini, A.; Görtz, Verena; Goodby, John W.; Gleeson, Helen F.

2014-01-01

We have determined experimentally the magnitude of the difference in the splay and bend flexoelectric coefficients, |e 1 − e 3|, of an oxadiazole bent-core liquid crystal by measuring the critical voltage for the formation of flexodomains together with their wave number. The coefficient |e 1 − e 3| is found to be a factor of 2–3 times higher than in most conventional calamitic nematic liquid crystals, varying from 8 pCm−1 to 20 pCm−1 across the ∼60 K—wide nematic regime. We have also calculat...
Beamline electrostatic levitator for in situ high energy x-ray diffraction studies of levitated solids and liquids

Energy Technology Data Exchange (ETDEWEB)

Gangopadhyay, A.K.; Lee, G.W.; Kelto, K.F.; Rogers, J.R.; Goldman, A.I.; Robinson, D.S.; Rathz, T.J.; Hyers, R.W. (WU); (UAB); (NASA); (UMASS, Amherst)

2010-07-19

Determinations of the phase formation sequence, crystal structures and the thermo-physical properties of materials at high temperatures are hampered by contamination from the sample container and environment. Containerless processing techniques, such as electrostatic (ESL), electromagnetic, aerodynamic, and acoustic levitation, are most suitable for these studies. An adaptation of ESL for in situ structural studies of a wide range of materials using high energy (30-130 keV) x rays at a synchrotron source is described here. This beamline ESL (BESL) allows the in situ determination of the atomic structures of equilibrium solid and liquid phases, undercooled liquids and time-resolved studies of solid-solid and liquid-solid phase transformations. The use of area detectors enables the rapid acquisition of complete diffraction patterns over a wide range (0.5-14 {angstrom}{sup -1}) of reciprocal space. The wide temperature range (300-2500 K), containerless processing environment under high vacuum (10{sup -7}-10{sup -8} Torr), and fast data acquisition capability, make BESL particularly well suited for phase stability studies of high temperature solids and liquids. An additional, but important, feature of BESL is the capability for simultaneous measurements of a host of thermo-physical properties including the specific heat, enthalpy of transformation, solidus and liquidus temperatures, density, viscosity, and surface tension, all on the same sample during the structural measurements.
I19, the small-molecule single-crystal diffraction beamline at Diamond Light Source.

Science.gov (United States)

Nowell, Harriott; Barnett, Sarah A; Christensen, Kirsten E; Teat, Simon J; Allan, David R

2012-05-01

The dedicated small-molecule single-crystal X-ray diffraction beamline (I19) at Diamond Light Source has been operational and supporting users for over three years. I19 is a high-flux tunable-wavelength beamline and its key details are described in this article. Much of the work performed on the beamline involves structure determination from small and weakly diffracting crystals. Other experiments that have been supported to date include structural studies at high pressure, studies of metastable species, variable-temperature crystallography, studies involving gas exchange in porous materials and structural characterizations that require analysis of the diffuse scattering between Bragg reflections. A range of sample environments to facilitate crystallographic studies under non-ambient conditions are available as well as a number of options for automation. An indication of the scope of the science carried out on the beamline is provided by the range of highlights selected for this paper.
The determination of the crystal structures of some uranium compounds by means of x-ray and neutron diffraction

International Nuclear Information System (INIS)

Adrian, H.W.W.

1977-10-01

In industrial uranium processing or reprocessing procedures, aqueous uranyl nitrate solutions are an intermediate product. The compounds, whose structures are reported, might prove valuable as alternative crystallization products to existing methods of extracting the uranium from solution. The compounds are obtained by the addition of hydroxylammonium to the uranyl nitrate solution and are of the general formula UO 2 (NH 2 0) 2 .xH 2 0, where x can take the values zero, two, three and four. In addition a compound of the formula UO 2 (NH 2 0) 2 .2(NH 2 CH).2H 2 0 was obtained. The UO 2 (NH 2 0) compound crystallized in a monoclinic crystal form. Crystals large enough for neutron diffraction were not obtained. The structure of the UO 2 (NH 2 0) 2 .2H 2 0 could not be solved because only disordered crystalline material was available. The structure of UO 2 (NH 2 0) 2 .3H 2 0 was solved by means of room- and low-temperature neutron diffraction. The unit cell is orthorhombic. The structure of α-UO 2 (NH 2 0) 2 .4H 2 0 was investigated by means of room-temperature x-ray and room- and low-temperature neutron diffraction. The unit cell is triclinic. This compound strongly resembles the trihydrate. The UO 2 (NH 2 0) 2 .2(NH 2 0H).2H 2 0 compound gave crystals large enough for single crystal x-ray but not neutron diffraction. The unit cell is orthorhombic. The characteristic powder patterns (indexed except for the dihydrate compound) of the above compounds are reported [af
Cholesteric colloidal liquid crystals from phytosterol rod-like particles

NARCIS (Netherlands)

Rossi, L.; Sacanna, S.; Velikov, K.P.

2011-01-01

We report the first observation of chiral colloidal liquid crystals of rod-like particles from a low molecular weight organic compound— phytosterols. Based on the particles shape and crystal structure, we attribute this phenomenon to chiral distribution of surface charge on the surface of
Reorientation of single-wall carbon nanotubes in negative anisotropy liquid crystals by an electric field

Directory of Open Access Journals (Sweden)

Amanda García-García

2016-06-01

Full Text Available Single-wall carbon nanotubes (SWCNT are anisotropic nanoparticles that can cause modifications in the electrical and electro-optical properties of liquid crystals. The control of the SWCNT concentration, distribution and reorientation in such self-organized fluids allows for the possibility of tuning the liquid crystal properties. The alignment and reorientation of CNTs are studied in a system where the liquid crystal orientation effect has been isolated. Complementary studies including Raman spectroscopy, microscopic inspection and impedance studies were carried out. The results reveal an ordered reorientation of the CNTs induced by an electric field, which does not alter the orientation of the liquid crystal molecules. Moreover, impedance spectroscopy suggests a nonnegligible anchoring force between the CNTs and the liquid crystal molecules.
Transflective multiplexing of holographic polymer dispersed liquid crystal using Si additives

Directory of Open Access Journals (Sweden)

2011-01-01

Full Text Available Morphology, grating formation dynamics and electro-optical performance of transflective multiplexing with holographic polymer dispersed liquid crystal (HPDLC were investigated in the presence of silica nanoparticles (Aerosil R812 (RS and modified Aerosil 200 (MS and silicon monomer (vinyltrimethoxy silane (VTMS by using three coherent laser beams. The addition of Si additive significantly augmented the diffraction efficiencies of transmission and reflection gratings due to the enhanced phase separation with large LC channels. The film was driven only with Si additives which are enriched at the polymer-LC interfaces. As the additive content increased, driving voltage decreased to a minimum of 30 V at 2.0 wt% VTMS. It was found that the interface modification and large droplet size are crucial to operate the film. Among the three types of Si additive, VTMS showed the highest electro-optical performance due to its low viscosity and high reactivity.
An electrically tunable plenoptic camera using a liquid crystal microlens array

International Nuclear Information System (INIS)

Lei, Yu; Tong, Qing; Zhang, Xinyu; Sang, Hongshi; Ji, An; Xie, Changsheng

2015-01-01

Plenoptic cameras generally employ a microlens array positioned between the main lens and the image sensor to capture the three-dimensional target radiation in the visible range. Because the focal length of common refractive or diffractive microlenses is fixed, the depth of field (DOF) is limited so as to restrict their imaging capability. In this paper, we propose a new plenoptic camera using a liquid crystal microlens array (LCMLA) with electrically tunable focal length. The developed LCMLA is fabricated by traditional photolithography and standard microelectronic techniques, and then, its focusing performance is experimentally presented. The fabricated LCMLA is directly integrated with an image sensor to construct a prototyped LCMLA-based plenoptic camera for acquiring raw radiation of targets. Our experiments demonstrate that the focused region of the LCMLA-based plenoptic camera can be shifted efficiently through electrically tuning the LCMLA used, which is equivalent to the extension of the DOF
Expression, purification, crystallization and preliminary diffraction studies of the mammalian DAG kinase homologue YegS from Escherichia coli

International Nuclear Information System (INIS)

Bakali H, M. Amin; Nordlund, Pär; Hallberg, B. Martin

2006-01-01

The overexpression, crystallization and preliminary diffraction analysis of E. coli YegS are reported. yegS is a gene encoding a 32 kDa cytosolic protein with unknown function but with strong sequence homology to a family of structurally uncharacterized eukaryotic non-protein kinases: diacylglycerol kinases, sphingosine kinases and ceramide kinases. Here, the overexpression, crystallization and preliminary diffraction analysis of Escherichia coli YegS are reported. The crystals belong to space group P2 1 , with unit-cell parameters a = 42.4, b = 166.1, c = 48.5 Å, β = 96.97°. The presence of a dimer in the asymmetric unit was estimated to give a Matthews coefficient (V M ) of 2.5 Å 3 Da −1 and a solvent content of 50.8%(v/v). Single-wavelength diffraction data were collected to a resolution of 1.9 Å using synchrotron radiation
Sharp Morphological Transitions from Nanoscale Mixed-Anchoring Patterns in Confined Nematic Liquid Crystals

Energy Technology Data Exchange (ETDEWEB)

Armas-Pérez, Julio C. [Institute; División; Li, Xiao [Institute; Martínez-González, José A. [Institute; Smith, Coleman [Institute; Hernández-Ortiz, J. P. [Departamento; Nealey, Paul F. [Institute; Materials; de Pablo, Juan J. [Institute; Materials

2017-08-17

Liquid crystals are known to be particularly sensitive to orientational cues provided at surfaces or interfaces. In this work, we explore theoretically, computationally, and experimentally the behavior of liquid crystals on isolated nanoscale patterns with controlled anchoring characteristics at small length scales. The orientation of the liquid crystal is controlled through the use of chemically patterned polymer brushes that are tethered to a surface. This system can be engineered with remarkable precision, and the central question addressed here is whether a characteristic length scale exists at which information encoded on a surface is no longer registered by a liquid crystal. To do so, we adopt a tensorial description of the free energy of the hybrid liquidcrystal surface system, and we investigate its morphology in a systematic manner. For long and narrow surface stripes, it is found that the liquid crystal follows the instructions provided by the pattern down to 100 nm widths. This is accomplished through the creation of line defects that travel along the sides of the stripes. We show that a "sharp" morphological transition occurs from a uniform undistorted alignment to a dual uniform/splay-bend morphology. The theoretical and numerical predictions advanced here are confirmed by experimental observations. Our combined analysis suggests that nanoscale patterns can be used to manipulate the orientation of liquid crystals at a fraction of the energetic cost that is involved in traditional liquid crystal-based devices. The insights presented in this work have the potential to provide a new fabrication platform to assemble low power bistable devices, which could be reconfigured upon application of small external fields.
Out-of-equilibrium processes in suspensions of oppositely charged colloids: liquid-to-crystal nucleation and gel formation

Science.gov (United States)

Sanz, Eduardo

2009-03-01

We study the kinetics of the liquid-to-crystal transformation and of gel formation in colloidal suspensions of oppositely charged particles. We analyse, by means of both computer simulations and experiments, the evolution of a fluid quenched to a state point of the phase diagram where the most stable state is either a homogeneous crystalline solid or a solid phase in contact with a dilute gas. On the one hand, at high temperatures and high packing fractions, close to an ordered-solid/disordered-solid coexistence line, we find that the fluid-to-crystal pathway does not follow the minimum free energy route. On the other hand, a quench to a state point far from the ordered-crystal/disordered-crystal coexistence border is followed by a fluid-to-solid transition through the minimum free energy pathway. At low temperatures and packing fractions we observe that the system undergoes a gas-liquid spinodal decomposition that, at some point, arrests giving rise to a gel-like structure. Both our simulations and experiments suggest that increasing the interaction range favors crystallization over vitrification in gel-like structures. [4pt] In collaboration with Chantal Valeriani, Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands and SUPA, School of Physics, University of Edinburgh, JCMB King's Buildings, Mayfield Road, Edinburgh EH9 3JZ, UK; Teun Vissers, Andrea Fortini, Mirjam E. Leunissen, and Alfons van Blaaderen, Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University; Daan Frenke, FOM Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ Amsterdam, The Netherlands and Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW, Cambridge, UK; and Marjolein Dijkstra, Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University.
Increasing the X-ray Diffraction Power of Protein Crystals by Dehydration: The Case of Bovine Serum Albumin and a Survey of Literature Data

Directory of Open Access Journals (Sweden)

Irene Russo Krauss

2012-03-01

Full Text Available Serum albumin is one of the most widely studied proteins. It is the most abundant protein in plasma with a typical concentration of 5 g/100 mL and the principal transporter of fatty acids in plasma. While the crystal structures of human serum albumin (HSA free and in complex with fatty acids, hemin, and local anesthetics have been characterized, no crystallographic models are available on bovine serum albumin (BSA, presumably because of the poor diffraction power of existing hexagonal BSA crystals. Here, the crystallization and diffraction data of a new BSA crystal form, obtained by the hanging drop method using MPEG 5K as precipitating agent, are presented. The crystals belong to space group C2, with unit-cell parameters a = 216.45 Å, b = 44.72 Å, c = 140.18 Å, β = 114.5°. Dehydration was found to increase the diffraction limit of BSA crystals from ~8 Å to 3.2 Å, probably by improving the packing of protein molecules in the crystal lattice. These results, together with a survey of more than 60 successful cases of protein crystal dehydration, confirm that it can be a useful procedure to be used in initial screening as a method of improving the diffraction limits of existing crystals.
Crystallization and preliminary X-ray diffraction analysis of recombinant hepatitis E virus-like particle

International Nuclear Information System (INIS)

Wang, Che-Yen; Miyazaki, Naoyuki; Yamashita, Tetsuo; Higashiura, Akifumi; Nakagawa, Atsushi; Li, Tian-Cheng; Takeda, Naokazu; Xing, Li; Hjalmarsson, Erik; Friberg, Claes; Liou, Der-Ming; Sung, Yen-Jen; Tsukihara, Tomitake; Matsuura, Yoshiharu; Miyamura, Tatsuo; Cheng, R. Holland

2008-01-01

A recombinant virus-like particle that is a potential oral hepatitis E vaccine was crystallized. Diffraction data were collected to 8.3 Å resolution and the X-ray structure was phased with the aid of a low-resolution density map determined using cryo-electron microscopy data. Hepatitis E virus (HEV) accounts for the majority of enterically transmitted hepatitis infections worldwide. Currently, there is no specific treatment for or vaccine against HEV. The major structural protein is derived from open reading frame (ORF) 2 of the viral genome. A potential oral vaccine is provided by the virus-like particles formed by a protein construct of partial ORF3 protein (residue 70–123) fused to the N-terminus of the ORF2 protein (residues 112–608). Single crystals obtained by the hanging-drop vapour-diffusion method at 293 K diffract X-rays to 8.3 Å resolution. The crystals belong to space group P2 1 2 1 2 1 , with unit-cell parameters a = 337, b = 343, c = 346 Å, α = β = γ = 90°, and contain one particle per asymmetric unit
Mixing effects in the crystallization of supercooled quantum binary liquids

International Nuclear Information System (INIS)

Kühnel, M.; Kalinin, A.; Fernández, J. M.; Tejeda, G.; Moreno, E.; Montero, S.; Tramonto, F.; Galli, D. E.; Nava, M.; Grisenti, R. E.

2015-01-01

By means of Raman spectroscopy of liquid microjets, we have investigated the crystallization process of supercooled quantum liquid mixtures composed of parahydrogen (pH 2 ) or orthodeuterium (oD 2 ) diluted with small amounts of neon. We show that the introduction of the Ne impurities affects the crystallization kinetics in terms of a significant reduction of the measured pH 2 and oD 2 crystal growth rates, similarly to what found in our previous work on supercooled pH 2 -oD 2 liquid mixtures [Kühnel et al., Phys. Rev. B 89, 180201(R) (2014)]. Our experimental results, in combination with path-integral simulations of the supercooled liquid mixtures, suggest in particular a correlation between the measured growth rates and the ratio of the effective particle sizes originating from quantum delocalization effects. We further show that the crystalline structure of the mixtures is also affected to a large extent by the presence of the Ne impurities, which likely initiate the freezing process through the formation of Ne-rich crystallites
Mixing effects in the crystallization of supercooled quantum binary liquids

Energy Technology Data Exchange (ETDEWEB)

Kühnel, M.; Kalinin, A. [Institut für Kernphysik, J. W. Goethe-Universität, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany); Fernández, J. M.; Tejeda, G.; Moreno, E.; Montero, S. [Laboratory of Molecular Fluid Dynamics, Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid (Spain); Tramonto, F.; Galli, D. E. [Laboratorio di Calcolo Parallelo e di Simulazioni di Materia Condensata, Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); Nava, M. [Laboratorio di Calcolo Parallelo e di Simulazioni di Materia Condensata, Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); Computational Science, Department of Chemistry and Applied Biosciences, ETH Zurich, USI Campus, Via Giuseppe Buffi 13, CH-6900 Lugano (Switzerland); Grisenti, R. E. [Institut für Kernphysik, J. W. Goethe-Universität, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany); GSI - Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany)

2015-08-14

By means of Raman spectroscopy of liquid microjets, we have investigated the crystallization process of supercooled quantum liquid mixtures composed of parahydrogen (pH{sub 2}) or orthodeuterium (oD{sub 2}) diluted with small amounts of neon. We show that the introduction of the Ne impurities affects the crystallization kinetics in terms of a significant reduction of the measured pH{sub 2} and oD{sub 2} crystal growth rates, similarly to what found in our previous work on supercooled pH{sub 2}-oD{sub 2} liquid mixtures [Kühnel et al., Phys. Rev. B 89, 180201(R) (2014)]. Our experimental results, in combination with path-integral simulations of the supercooled liquid mixtures, suggest in particular a correlation between the measured growth rates and the ratio of the effective particle sizes originating from quantum delocalization effects. We further show that the crystalline structure of the mixtures is also affected to a large extent by the presence of the Ne impurities, which likely initiate the freezing process through the formation of Ne-rich crystallites.
Characterization of calcium crystals in Abelia using x-ray diffraction and electron microscopes

Science.gov (United States)

Localization, chemical composition, and morphology of calcium crystals in leaves and stems of Abelia mosanensis and A. ×grandiflora were analyzed with a variable pressure scanning electron microscope (VP-SEM) equipped with an X-ray diffraction system, low temperature SEM (LT-SEM) and a transmission ...

Liquid Crystal Phases of Colloidal Platelets and their Use as Nanocomposite Templates

NARCIS (Netherlands)

Mourad, M.C.D.|info:eu-repo/dai/nl/304837563

2009-01-01

This thesis explores the gelation and liquid crystal phase behavior of colloidal dispersions of platelike particles as well as the use of such dispersions for the generation of nanocomposites. We report on the sol-gel, sol-glass and liquid crystal phase transitions of positively charged colloidal
Synchrotron Bragg diffraction imaging characterization of synthetic diamond crystals for optical and electronic power device applications.

Science.gov (United States)

Tran Thi, Thu Nhi; Morse, J; Caliste, D; Fernandez, B; Eon, D; Härtwig, J; Barbay, C; Mer-Calfati, C; Tranchant, N; Arnault, J C; Lafford, T A; Baruchel, J

2017-04-01

Bragg diffraction imaging enables the quality of synthetic single-crystal diamond substrates and their overgrown, mostly doped, diamond layers to be characterized. This is very important for improving diamond-based devices produced for X-ray optics and power electronics applications. The usual first step for this characterization is white-beam X-ray diffraction topography, which is a simple and fast method to identify the extended defects (dislocations, growth sectors, boundaries, stacking faults, overall curvature etc. ) within the crystal. This allows easy and quick comparison of the crystal quality of diamond plates available from various commercial suppliers. When needed, rocking curve imaging (RCI) is also employed, which is the quantitative counterpart of monochromatic Bragg diffraction imaging. RCI enables the local determination of both the effective misorientation, which results from lattice parameter variation and the local lattice tilt, and the local Bragg position. Maps derived from these parameters are used to measure the magnitude of the distortions associated with polishing damage and the depth of this damage within the volume of the crystal. For overgrown layers, these maps also reveal the distortion induced by the incorporation of impurities such as boron, or the lattice parameter variations associated with the presence of growth-incorporated nitrogen. These techniques are described, and their capabilities for studying the quality of diamond substrates and overgrown layers, and the surface damage caused by mechanical polishing, are illustrated by examples.
Dynamic Diffraction Studies on the Crystallization, Phase Transformation, and Activation Energies in Anodized Titania Nanotubes

OpenAIRE

Hani Albetran; Victor Vega; Victor M. Prida; It-Meng Low

2018-01-01

The influence of calcination time on the phase transformation and crystallization kinetics of anodized titania nanotube arrays was studied using in-situ isothermal and non-isothermal synchrotron radiation diffraction from room temperature to 900 °C. Anatase first crystallized at 400 °C, while rutile crystallized at 550 °C. Isothermal heating of the anodized titania nanotubes by an increase in the calcination time at 400, 450, 500, 550, 600, and 650 °C resulted in a slight reduction in anatase...
Synchrotron X-ray diffraction using triple-axis spectrometry

International Nuclear Information System (INIS)

Als-Nielsen, J.

1980-12-01

High resolution X-ray diffraction studies of (i) monolayers of the noble gases Kr and Ar physiosorbed on graphite (ii) smectic A fluctuations in the nematic and the smectic A phases of liquid crystals are described. The apparatus used is a triple axis spectrometer situated at the storage ring DORIS at Hasylab, DESY, Hamburg. A monochromatic, well collimated beam is extracted from the synchrotron radiation spectrum by Bragg reflection from perfect Si or Ge crystals. The direction of the beam scattered from the sample is determined by Bragg reflection from a perfect Si or Ge crystal. High intensities even with resolution extending beyond the wavelength of visible light can be obtained. (Auth.)
Hydrogen bonding discotic liquid crystals: Synthesis, self-assembly, and molecular recognition

Science.gov (United States)

Bushey, Mark Lawrence

The triamides shown below form discotic liquid crystalline phases with intermolecular hydrogen bonding stabilizing the columnar structure, A and B. The mesomorphic orientations of the columns are dependent on the amide side chain. Three mesophasic orientations are described: columns aligned perpendicular to the surface, columns aligned parallel to the surface in a radial pattern, and columns aligned parallel to the surface in a parallel or aligned pattern. The aggregation of the tridodecyloxy-triamides show N-H shifting in the IR at elevated temperatures, an indication that hydrogen bonding is important in the association of liquid crystalline mesophases. Powder X-ray diffraction studies indicate packing of the columns into a hexagonal lattice.* Studies on triamides with chiral side chains result in molecules stacking into columns displaying a helical pitch. In concentrated solutions of dodecane, molecules with chiral side chains display behavior consistent with chiral nematic liquid crystals; a super helical packing of the chiral columns. These superhelical packed systems show temperature dependent selective reflection of visible light and fingerprint textures. Atomic force microscopy (AFM) confirms in sub-monolayer films, that molecules preferring an edge-on orientation form long columns on highly ordered pyrolytic graphite (HOPG), those that prefer a face-on orientation form large amorphous domains. Electrostatic force microscopy (EFM) images of the domains of molecules in the edge-on orientation provides no discernible polarity, imaging of the domains of molecules in the face-on orientation indicates a negative polar orientation. Scanning probe measurements (SPM) of the tridodecynyl-triamide have shown similar edge-on orientations of other tridodecyloxy-triamides. Powder X-ray diffraction of these liquid crystalline phases shows a hexagonal packing of the columnar assembly. Electro-optic switching studies indicate a piezoelectric switching mechanism, possibly
Magneto-optic dynamics in a ferromagnetic nematic liquid crystal

Science.gov (United States)

Potisk, Tilen; Mertelj, Alenka; Sebastián, Nerea; Osterman, Natan; Lisjak, Darja; Brand, Helmut R.; Pleiner, Harald; Svenšek, Daniel

2018-01-01

We investigate dynamic magneto-optic effects in a ferromagnetic nematic liquid crystal experimentally and theoretically. Experimentally we measure the magnetization and the phase difference of the transmitted light when an external magnetic field is applied. As a model we study the coupled dynamics of the magnetization, M , and the director field, n , associated with the liquid crystalline orientational order. We demonstrate that the experimentally studied macroscopic dynamic behavior reveals the importance of a dynamic cross-coupling between M and n . The experimental data are used to extract the value of the dissipative cross-coupling coefficient. We also make concrete predictions about how reversible cross-coupling terms between the magnetization and the director could be detected experimentally by measurements of the transmitted light intensity as well as by analyzing the azimuthal angle of the magnetization and the director out of the plane spanned by the anchoring axis and the external magnetic field. We derive the eigenmodes of the coupled system and study their relaxation rates. We show that in the usual experimental setup used for measuring the relaxation rates of the splay-bend or twist-bend eigenmodes of a nematic liquid crystal one expects for a ferromagnetic nematic liquid crystal a mixture of at least two eigenmodes.
Room-temperature serial crystallography using a kinetically optimized microfluidic device for protein crystallization and on-chip X-ray diffraction

Directory of Open Access Journals (Sweden)

Michael Heymann

2014-09-01

Full Text Available An emulsion-based serial crystallographic technology has been developed, in which nanolitre-sized droplets of protein solution are encapsulated in oil and stabilized by surfactant. Once the first crystal in a drop is nucleated, the small volume generates a negative feedback mechanism that lowers the supersaturation. This mechanism is exploited to produce one crystal per drop. Diffraction data are measured, one crystal at a time, from a series of room-temperature crystals stored on an X-ray semi-transparent microfluidic chip, and a 93% complete data set is obtained by merging single diffraction frames taken from different unoriented crystals. As proof of concept, the structure of glucose isomerase was solved to 2.1 Å, demonstrating the feasibility of high-throughput serial X-ray crystallography using synchrotron radiation.
NATO Advanced Research Workshop on Incommensurate Crystals, Liquid Crystals, and Quasi-Crystals

CERN Document Server

Clark, N

1988-01-01

In this NATO-sponsored Advanced Research Workshop we succeeded in bringing together approximately forty scientists working in the three main areas of structurally incommensurate materials: incommensurate crystals (primarily ferroelectric insulators), incommensurate liquid crystals, and metallic quasi-crystals. Although these three classes of materials are quite distinct, the commonality of the physics of the origin and descrip tion of these incommensurate structures is striking and evident in these proceedings. A measure of the success of this conference was the degree to which interaction among the three subgroups occurred; this was facili tated by approximately equal amounts of theory and experiment in the papers presented. We thank the University of Colorado for providing pleasant housing and conference facilities at a modest cost, and we are especially grate ful to Ann Underwood, who retyped all the manuscripts into camera-ready form. J. F. Scott Boulder, Colorado N. A. Clark v CONTENTS PART I: INCO...
Isolation, crystallization and preliminary X-ray diffraction analysis of l-amino-acid oxidase from Vipera ammodytes ammodytes venom

International Nuclear Information System (INIS)

Georgieva, Dessislava; Kardas, Anna; Buck, Friedrich; Perbandt, Markus; Betzel, Christian

2008-01-01

A novel l-amino-acid oxidase was isolated from V. ammodytes ammodytes venom and crystallized. The solution conditions under which the protein sample was monodisperse were optimized using dynamic light scattering prior to crystallization. Preliminary diffraction data were collected to 2.6 Å resolution. l-Amino-acid oxidase from the venom of Vipera ammodytes ammodytes, the most venomous snake in Europe, was isolated and crystallized using the sitting-drop vapour-diffusion method. The solution conditions under which the protein sample was monodisperse were optimized using dynamic light scattering prior to crystallization. The crystals belonged to space group C2, with unit-cell parameters a = 198.37, b = 96.38, c = 109.11 Å, β = 92.56°. Initial diffraction data were collected to 2.6 Å resolution. The calculated Matthews coefficient is approximately 2.6 Å 3 Da −1 assuming the presence of four molecules in the asymmetric unit
Retinal axial focusing and multi-layer imaging with a liquid crystal adaptive optics camera

International Nuclear Information System (INIS)

Liu Rui-Xue; Zheng Xian-Liang; Li Da-Yu; Hu Li-Fa; Cao Zhao-Liang; Mu Quan-Quan; Xuan Li; Xia Ming-Liang

2014-01-01

With the help of adaptive optics (AO) technology, cellular level imaging of living human retina can be achieved. Aiming to reduce distressing feelings and to avoid potential drug induced diseases, we attempted to image retina with dilated pupil and froze accommodation without drugs. An optimized liquid crystal adaptive optics camera was adopted for retinal imaging. A novel eye stared system was used for stimulating accommodation and fixating imaging area. Illumination sources and imaging camera kept linkage for focusing and imaging different layers. Four subjects with diverse degree of myopia were imaged. Based on the optical properties of the human eye, the eye stared system reduced the defocus to less than the typical ocular depth of focus. In this way, the illumination light can be projected on certain retina layer precisely. Since that the defocus had been compensated by the eye stared system, the adopted 512 × 512 liquid crystal spatial light modulator (LC-SLM) corrector provided the crucial spatial fidelity to fully compensate high-order aberrations. The Strehl ratio of a subject with −8 diopter myopia was improved to 0.78, which was nearly close to diffraction-limited imaging. By finely adjusting the axial displacement of illumination sources and imaging camera, cone photoreceptors, blood vessels and nerve fiber layer were clearly imaged successfully. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
High-speed imaging polarimetry using liquid crystal modulators

Directory of Open Access Journals (Sweden)

Ambs P.

2010-06-01

Full Text Available This paper deals with dynamic polarimetric imaging techniques. The basics of modern polarimetry have been known for one and a half century, but no practical high-speed implementation providing the full polarization information is currently available. Various methods are reviewed which prove to be a trade-off between the complexity of the optical set-up and the amount of polarimetric information they provide (ie the number of components of the Stokes vector. Techniques using liquid crystal devices, incepted in the late 1990's, are emphasized. Optical set-ups we implemented are presented. We particularly focus on high-speed techniques (i.e. faster than 200 Hz using ferroelectric liquid crystal devices.
Validation of molecular crystal structures from powder diffraction data with dispersion-corrected density functional theory (DFT-D)

DEFF Research Database (Denmark)

van de Streek, Jacco; Neumann, Marcus A

2014-01-01

In 2010 we energy-minimized 225 high-quality single-crystal (SX) structures with dispersion-corrected density functional theory (DFT-D) to establish a quantitative benchmark. For the current paper, 215 organic crystal structures determined from X-ray powder diffraction (XRPD) data and published...
Dye-Induced Enhancement of Optical Nonlinearity in Liquids and Liquid Crystals

International Nuclear Information System (INIS)

Muenster, R.; Jarasch, M.; Zhuang, X.; Shen, Y.

1997-01-01

Optical nonlinearity of liquid crystals (LC) in the isotropic phase can be enhanced by 1 order of magnitude by dissolving 0.1% of anthraquinone dye in the LC. The enhancement decreases by ∼30% when the LC transforms into the nematic phase. The same guest-host effect also exists in non-LC liquids. It can be explained by a model based on the change of guest-host interaction induced by optical excitations of the dye. copyright 1996 The American Physical Society
Crystallization and preliminary X-ray diffraction analysis of salutaridine reductase from the opium poppy Papaver somniferum

International Nuclear Information System (INIS)

Higashi, Yasuhiro; Smith, Thomas J.; Jez, Joseph M.; Kutchan, Toni M.

2010-01-01

Recombinant P. somniferum salutaridine reductase (SalR) was purified and crystallized with NADPH using the hanging-drop vapor-diffusion method. Crystals of the SalR–NADPH complex diffracted X-rays to a resolution of 1.9 Å. The opium poppy Papaver somniferum is the source of the narcotic analgesics morphine and codeine. Salutaridine reductase (SalR; EC 1.1.1.248) reduces the C-7 keto group of salutaridine to the C-7 (S)-hydroxyl group of salutaridinol in the biosynthetic pathway that leads to morphine in the opium poppy plant. P. somniferum SalR was overproduced in Escherichia coli and purified using cobalt-affinity and size-exclusion chromatography. Hexagonal crystals belonging to space group P6 4 22 or P6 2 22 were obtained using ammonium sulfate as precipitant and diffracted to a resolution of 1.9 Å
Liquid Crystals of Lithium Dodecylbenzenesulfonate for Electric Double Layer Capacitors

International Nuclear Information System (INIS)

Kuzmin, Andrey Vasil’evich; Yurtov, Evgeny V.

2016-01-01

Ionic lyotropic liquid crystals based on lithium dodecylbenzenesulfonate were used as electrolytes for electric double layer capacitors with carbon fibrous electrodes. The capacitors were tasted by cyclic voltammetry, galvanostatic charge and discharge, and impedance spectroscopy. The highest specific capacitance was achieved for electrical double layer capacitor equipped with ionic lyotropic liquid crystal of lithium dodecylbenzenesulfonate 35 wt% in water. The specific capacitance of capacitor was calculated from galvanostatic discharge curves – 15 F/g of carbon fibrous material
Electro-optical properties of low viscosity driven holographic polymer dispersed liquid crystals

Science.gov (United States)

Moon, K. R.; Bae, S. Y.; Kim, B. K.

2015-04-01

Relative diffraction efficiency (RDE), operating voltage, and response times are most important performance characteristics of holographic polymer dispersed liquid crystals (HPDLC). Two types of triallyl isocyanurate (TI) having different structures were incorporated into the conventional transmission grating of HPDLC. Premix viscosity decreased by 13-18% with up to 3% TI, beyond which it increased. TI eliminated induction period and augmented initial grating formation rate at all contents. Saturation RDE increased over 200% while threshold voltage and rise time decreased to about half and 2/3, respectively up to 3% TI, beyond which the tendencies were reversed. Among the two TIs, low viscosity monomer (TA) showed high RDE, while high miscibility monomer (TE) low characteristic voltages and short response times. It is concluded that grating formation is largely favored by low viscosity, while interface tensions and electro-optical performances by miscibility at similar viscosities.
Crystallization and preliminary X-ray diffraction studies of FAD synthetase from Corynebacterium ammoniagenes

International Nuclear Information System (INIS)

Herguedas, Beatriz; Martínez-Júlvez, Marta; Frago, Susana; Medina, Milagros; Hermoso, Juan A.

2009-01-01

Native and selenomethionine-labelled FAD synthetase from C. ammoniagenes have been crystallized by the hanging-drop vapour-diffusion method. A MAD data set for SeMet-labelled FAD synthetase was collected to 2.42 Å resolution, while data sets were collected to 1.95 Å resolution for the native crystals. FAD synthetase from Corynebacterium ammoniagenes (CaFADS), a prokaryotic bifunctional enzyme that catalyses the phosphorylation of riboflavin as well as the adenylylation of FMN, has been crystallized using the hanging-drop vapour-diffusion method at 277 K. Diffraction-quality cubic crystals of native and selenomethionine-labelled (SeMet-CaFADS) protein belonged to the cubic space group P2 1 3, with unit-cell parameters a = b = c = 133.47 Å and a = b = c = 133.40 Å, respectively. Data sets for native and SeMet-containing crystals were collected to 1.95 and 2.42 Å resolution, respectively
About some practical aspects of X-ray diffraction : From single crystal to powders

Energy Technology Data Exchange (ETDEWEB)

Giacovazzo, C [Bari Univ. (Italy). Dip. Geomineralogico

1996-09-01

An ideal polycrystalline material or power is an ensemble of a very large number of randomly oriented crystallites. It is shown the effect that this random orientation has on the diffraction of a specimen assumed to contain only one reciprocal lattice node. The most remarkable difference with the single-crystal case is that now must think of scattering vectors not as lying on discrete nodes of reciprocal lattice vectors, the distances from the single-crystal reciprocal lattice nodes to the origin of reciprocal space.
About some practical aspects of X-ray diffraction : From single crystal to powders

International Nuclear Information System (INIS)

Giacovazzo, C.

1996-01-01

An ideal polycrystalline material or power is an ensemble of a very large number of randomly oriented crystallites. It is shown the effect that this random orientation has on the diffraction of a specimen assumed to contain only one reciprocal lattice node. The most remarkable difference with the single-crystal case is that now must think of scattering vectors not as lying on discrete nodes of reciprocal lattice vectors, the distances from the single-crystal reciprocal lattice nodes to the origin of reciprocal space
Smart lighting using a liquid crystal modulator

Science.gov (United States)

Baril, Alexandre; Thibault, Simon; Galstian, Tigran

2017-08-01

Now that LEDs have massively invaded the illumination market, a clear trend has emerged for more efficient and targeted lighting. The project described here is at the leading edge of the trend and aims at developing an evaluation board to test smart lighting applications. This is made possible thanks to a new liquid crystal light modulator recently developed for broadening LED light beams. The modulator is controlled by electrical signals and is characterized by a linear working zone. This feature allows the implementation of a closed loop control with a sensor feedback. This project shows that the use of computer vision is a promising opportunity for cheap closed loop control. The developed evaluation board integrates the liquid crystal modulator, a webcam, a LED light source and all the required electronics to implement a closed loop control with a computer vision algorithm.

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