Low Angle Region Research Articles

In-house characterization of protein powder

X-ray powder diffraction patterns of lysozyme and insulin were recorded on a standard in-house powder diffractometer. The experimental powder diffraction patterns were compared with patterns calculated from Protein Data Bank coordinate data. Good agreement was obtained by including straightforward corrections for background, unit-cell parameters, disordered bulk solvent and geometric factors. In particular the solvent correction was found crucial for a good agreement. A revised Lorentz factor was derived, which gave a minor, but significant, improvement to the fit in the low-angle region. An attempt to include calculated H-atom positions did not improve the overall fit and was abandoned. The method devised was shown to be a quick and convenient tool for distinguishing precipitates and polymorphs of proteins.

507 透過法を用いた高分子材料のX線応力測定(OS5-2 回折法による材料評価)

The residual stresses in high-density polyethylene (HDPE) were measured using an x-ray stress measurement technique. There are two problems associated with this measurement Firstly, the diffraction peaks of the polymer appear in the low 2θ angle region and therefore the measurement accuracy for strains reduces. Secondly, the low 2θ angle region makes it extremely difficult to use the sin^2ψ method. In the present study we tried to use a transmission method for measuring the residual stress in HDPE samples to resolve these problems. The HDPE sample is shaped into thin sheets which have the three kinds of crystallinity degrees. The measured data is fitted with a good linear regression line in a 2θ-sin^2ψ diagram and the gradient of the regression line corresponded to the applied stress. On the other hand, the results of the residual stress measurement are deeply associated with degrees of the crystallinity in the HDPE material. The quantitative estimation of crystallinity degrees in the HDPE material was accomplished by a sink-float method. The residual stress distributions were discussed between micro-residual stresses in the crystal phase of HDPE with the amorphous phase of it. Finally, x-ray elastic constant (XEC) of FIDPE was estimated in these cases.

X-ray Residual Stress Measurement of Fiber Reinforced Plastic Composite

In this study, the residual stresses in high-density polyethylene (HDPE) and a fiber reinforced polyethylene was measured using an x-ray stress measurement technique. There have been few reports published of residual stress investigations in polymeric materials by x-ray stress measurements based on conventional x-ray reflection methods. There are two problems associated with this measurement. Firstly, the diffraction peaks of the polymer appear in the low 2θ angle region and therefore the measurement accuracy for strains reduces. Secondly, the low 2θ angle region makes it extremely difficult to use the sin2ψ method. In the present study we tried to use a transmission method for measuring the residual stress in HDPE samples to resolve these problems. The HDPE sample is shaped into thin sheets which have the three kinds of crystallinity degrees. The measured data is fitted with a good linear regression line in a 2θ-sin2ψ diagram and the gradient of the regression line corresponded to the applied stress. On the other hand, the results of the residual stress measurement are deeply associated with degrees of the crystallinity in the HDPE material. The quantitative estimation of crystallinity degrees in the HDPE material was accomplished by a sink-float method. The residual stress distributions were discussed between micro-residual stresses in the crystal phase of HDPE with the amorphous phase of it. Finally, x-ray elastic constant (XEC) of HDPE was estimated and the residual stresses in the fiber reinforced polyethylene was also measured by use of this XEC parameter.

Measuring DNA Condensation Driven by Cobalt Hexamine

We investigate the mechanism of DNA condensation mediated by trivalent cobalt hexammine (cohex) in solution, using 3 established experimental techniques. The amount of DNA precipitated out of the solution can be calculated by directly measuring the change of the UV absorption of the supernatant. Inter-DNA attraction is monitored by changes in the low angle region of small angle X-ray scattering (SAXS) profiles. Wide angle X-ray scattering (WAXS) is also applied to explore shorter length scales. Comparison with simulations reveals details of cohex association to DNA.

Tile and crystal calorimeters for the KLOE 2 experiment

The upgrade of the DA$\Phi$NE machine layout requires a modification of the size and position of the inner focusing quadrupoles of KLOE$^2$ thus asking for the realization of two new calorimeters covering the quadrupoles area. To improve the reconstruction of $K_L\to 2\pi^0$ events with photons hitting the quadrupoles, a tile calorimeter, QCALT, with high efficiency to low energy photons (20-300 MeV), time resolution of less than 1 ns and space resolution of few cm, is needed. We propose a tile calorimeter with a high granularity readout corresponding to about 2500 silicon photomultipliers (SiPM) of $1\times 1$ mm$^2$ area. Moreover, the low polar angle regions need the realization of a dense crystal calorimeter with very high time resolution performances to extend the acceptance for multiphotons events. Best candidates for this calorimeter are LYSO crystals with APD readout or PbWO$_4$ crystals with large area SIPM readout.

Structure studies of the nematic phase formed by bent-core molecules

In recent years there are several reports showing that bent-core mesogenic molecules are able to form biaxial nematic phase in which molecular rotation around the long molecular axis is strongly hindered. The x-ray pattern with azimuthally split signals at low angle region of diffraction is usually given as evidence for the biaxial nematic phase. We show experimentally and theoretically that such x-ray pattern is due to the local smectic- C fluctuations ("cybotactic" groups) in the uniaxial nematic phase.

Effect of cholesterol on structural and mechanical properties of membranes depends on lipid chain saturation.

The effects of cholesterol on membrane bending modulus K(C), membrane thickness D(HH), the partial and apparent areas of cholesterol and lipid, and the order parameter S(xray) are shown to depend upon the number of saturated hydrocarbon chains in the lipid molecules. Particularly striking is the result that up to 40% cholesterol does not increase the bending modulus K(C) of membranes composed of phosphatidylcholine lipids with two cis monounsaturated chains, although it does have the expected stiffening effect on membranes composed of lipids with two saturated chains. The B fluctuational modulus in the smectic liquid crystal theory is obtained and used to discuss the interactions between bilayers. Our K(C) results motivate a theory of elastic moduli in the high cholesterol limit and they challenge the relevance of universality concepts. Although most of our results were obtained at 30 degrees C , additional data at other temperatures to allow consideration of a reduced temperature variable do not support universality for the effect of cholesterol on all lipid bilayers. If the concept of universality is to be valid, different numbers of saturated chains must be considered to create different universality classes. The above experimental results were obtained from analysis of x-ray scattering in the low angle and wide angle regions.

Self-Assembled Cylindrical and Vesicular Molecular Templates for Polyaniline Nanofibers and Nanotapes

We report a soft template approach based on a custom-designed novel surfactant-cum-dopant for size and shape tuning of polyaniline nanomaterials such as nanofibers and nanotapes via emulsion and dispersion polymerization routes. A new amphiphilic 4-(3-dodecyl-8-enylphenyloxy) butane sulfonic acid was synthesized by ring-opening of butanesultone with renewable resource cardanol. The new amphiphilic dopant forms spherical micelles in water and its critical micelle concentration was determined by dye encapsulation and surface tension methods. In the emulsion route, the amphiphilic dopant complexed with aniline to produce cylindrical micellar aggregates that template exclusively for polyaniline nanofibers. The dispersion of aniline+dopant in water/toluene solvent mixture produces vesicles that selectively template for polyaniline nanotapes. The mechanism of the polyaniline nanomaterials formation was investigated by dynamic light scattering (DLS) and high-resolution transmission electron microscopy (HR-TEM). DLS of the polymerization templates in water proved the presence of micrometer range aggregates, and TEM images confirmed the shape of the cylindrical and vesicular templates. The polyaniline nanomaterials were found soluble in water and polar organic solvents for structural characterization and composition analysis by 1H NMR spectroscopy. Absorbance spectra of the nanomaterials showed free carrier tail above 900 nm in the near IR region for the delocalization of electrons in the polaron band corresponding to expanded conformation of polyaniline chains. Wide angle X-ray diffraction showed two new peaks at low angle region with d-spacing of 26.5 and 13.6 A corresponding to lamellar ordering of polyaniline chains followed by interdigitations of the amphiphilic dopant in the nanomaterials.

Synthesis of Thick Mesoporous γ-Alumina Films, Loading of Pt Nanoparticles, and Use of the Composite Film as a Reusable Catalyst

Nanocrystalline mesoporous gamma-Al2O3 film of high thickness has been developed and characterized. The films were prepared on ordinary glass substrates by a single dip-coating method using boehmite (AlOOH) sols derived from aluminum tri-sec-butoxide in presence of cetyltrimethylammonium bromide (CTAB) as structure-directing agent. The dried films were heat-treated at 500 degrees C in air to remove the organics and strengthen the network. The GIXRD of the heat-treated (500 degrees C) film shows a broad peak in the low-angle region supporting the formation of worm-hole-like disordered mesostructures. The high-angle GIXRD, FTIR, and TEM of the films confirm the formation of gamma-Al2O3. N2 adsorption-desorption analyses showed that the heat-treated (500 degrees C) film has a BET surface area of 171 m(2) g(-1) with a pore volume of 0.188 cm(3) g(-1) and mean pore diameter 4.3 nm. Pt nanoparticles (NPs) (approximately 2.7 mol % with respect to the equivalent AlO(1.5)) were generated inside the mesopores of the heat-treated films simply by soaking H2PtCl6 solutions into it, and followed by thermal decomposition at 500 degrees C. The surface area and pore volume of the Pt-incorporated film have been reduced to 101 m(2) g(-1) and 0.119 cm(3) g(-1) respectively, confirming the inclusion of Pt NPs inside the pores. FESEM and TEM studies revealed uniform distribution of Pt NPs (2-8.5 nm; average diameter 4.9 nm) in the films. Catalytic properties of the Pt-incorporated films were investigated in two model (one inorganic and other organic) systems: reduction of hexacyanoferrate(III) ions by thiosulfate to ferrocyanide, and p-nitrophenol to p-aminophenol. In both the cases, the catalyst showed excellent activities, and the reduction reactions followed smoothly, showing isosbestic points in the UV-visible spectra. The catalyst films can be separated easily after the reactions and reused several times.

すべり摩擦を受けた(001)銅単結晶における大角粒界の発達

A sliding wear test was conducted on a copper single crystal having (001) surface. In the vicinity of worn surface, equiaxed fine grains that were separated by high-angle boundaries were generated. On the other hand, formations of low-angle boundaries were predominant at the area distant from the worn surface. In the present study, the formation of low-angle boundaries that were perpendicular to the worn surface and evolution of the high-angle boundaries were investigated by the electron backscatter diffraction (EBSD) method. In the region where the low-angle boundaries were formed predominantly, lattice rotation occurred almost around the axis which is normal to the wear direction. However, from a detailed orientation analysis, local rotation axes were slightly different even in the same grain. The perpendicular low-angle boundaries could be introduced by a misorientation between adjoining areas that had such different rotation axes. Amount of the high-angle boundaries increased with decreasing depth from the worn surface. At the vicinity of the worn surface, many coincidence-site lattice (CSL) boundaries with various Σ-values were recognized. On the other hand, near the low-angle boundary region, the CSL boundaries were limited to Σ13a and Σ25a. This characteristic distribution of Σ-value could be understood from a model that the high-angle boundaries were generated by accumulated lattice rotation induced by the sliding wear.

Alkoxysilylation of Ti-MWW lamellar precursors into interlayer pore-expanded titanosilicates

Silylation of Ti-MWW lamellar precursor and subsequent calcination constructed an interlayer expanded structure, leading to novel titanosilicates with large pores. The silylating agents suitable for pore expansion were diethoxydimethylsilane, trimethylethoxysilane and triethoxymethylsilane containing methyl groups, which inhibited the intermolecular condensation of silanes effectively. In contrast to well-known 3D Ti-MWW with only medium pores of 10-membered rings, the silylation led to new crystalline structures with more open pores by ca. 2.5 A, as evidenced by the shift of layer-related diffractions to the lower-angle region in XRD patterns and the enlarged interlayer pores in HRTEM images. The interlayer expanded Ti-MWW was prepared readily from the corresponding hydrothermally synthesized precursors with a wide range of Ti contents (Si/Ti = 20–100). In addition, the pore expansion by silylation was realized under mild acid conditions with 0.1 M HNO3. The interlayer expanded Ti-MWW exhibited 3–7 times higher turnover number than 3D Ti-MWW in the oxidation of cyclohexene with H2O2.

Methodology for Synthesizing Crystalline Metallosilicates with Expanded Pore Windows Through Molecular Alkoxysilylation of Zeolitic Lamellar Precursors

Postalkoxysilylation with diethoxydimethylsilane has been carried out on the zeolitic lamellar precursors of various topologies such as MWW, FER, CDO and MCM-47 aiming to construct new crystalline structures with expanded pore apertures between the layers. The silylation process and the crystalline and pore structures of the resulting materials have been investigated with the techniques of XRD, IR, (13)C and (29)Si MAS NMR, ICP, SEM, HRTEM, elemental analyses, and N 2 adsorption. In contrast to forming known three-dimensional zeolite structures after direct calcination of the lamellar precursors, the silylation led to new crystalline structures with opener pores, as evidenced by the shift of layer-related diffractions to the lower-angle region in XRD patterns and the enlarged interlayer pores found by HRTEM images. After optimizing the treatment conditions, particularly the amount of silane agent, a maximum and homogeneous silylation was realized, which guaranteed the phase purity in interlayer expanded zeolites. The expanded structures were well preserved after calcination at 823 K or reflux in water for 1 to 2 weeks, indicating a high thermal stability and also a hydrothermal stability. The interlayer expanded zeolites prepared from the metallosilicate precursors of MWW topology exhibited higher catalytic activities in the redox and solid acid-catalyzed reactions of bulky molecules than that of their counterparts with conventional MWW topology.

Preparation and Properties of Metallocene-catalyzed PE/Starch Nanocomposites: Role of Nanocompatibilizer

Abstract The properties of metallocene catalyzed polyethylene (mPE)/starch blends and nanocomposites containing mPE-g-maleic anhydride (mPE-g-MA) compatibilizer, reinforced with 1 phr commercial organoclay (20A) at various amounts of pristine starch are discussed. The results from X-ray diffraction (XRD) and transmission electron microscope (TEM) experiments revealed that nanocomposites were achieved in all cases. No observable diffraction peaks in the low angle region were detected. Clay was preferentially located within the mPE and starch interface and the mPE matrix. The crystallization temperatures of nanocomposites increased with the addition of clay acting as a nucleating agent. However, the melting temperatures and the glass transition temperatures remained largely unchanged. Clay incorporation provided a heat barrier that profoundly increased the blend thermal stability. A maximum increase in tensile strength and Young's modulus was obtained, up to 60% and 105%, respectively, using nanoclay reinforced compatibilizer (termed nanocompatibilizer) in comparison with neat compatibilizer for pristine starch filled cases. Slightly lower water absorption capability was observed for nanocompatibilizer reinforced cases through the sheet-like structure of clay compared with neat compatibilizer cases.

Front-End electronics development for the new Resistive Plate Chamber detector of HADES

In this paper we present the new RPC wall, which is being installed in the HADES detector at Darmstadt GSI. It consists of time-of-flight (TOF) detectors used for both particle identification and triggering. Resistive Plate Chamber (RPC) detectors are becoming widely used because of their excellent TOF capabilities and reduced cost. The wall will contain 1024 RPC modules, covering an active area of around 7 m2, replacing the old TOFino detector at the low polar angle region. The excellent TOF and good charge resolutions of the new detector will improve the time resolution to values better than 100 ps. The Front-End electronics for the readout of the RPC signals is implemented with two types of boards to satisfy the space constraints: the Daughterboards are small boards that amplify the low level signals from the detector and provide fast discriminators for time of flight measurements, as well as an integrator for charge measurements. The Motherboard provides stable DC voltages and a stable ground, threshold DACs for the discriminators, multiplicity trigger and impedance matched paths for transfer of time window signals that contain information about time and charge. These signals are sent to a custom TDC board that label each event and send data through Ethernet to be conveniently stored.

Impact essential work of fracture of polypropylene/montmorillonite nanocomposites toughened with SEBS-g-MA elastomer

Poly(propylene) (PP)/organo-montmorillonite (Org-MMT) nanocomposites toughened with maleated styrene–ethylene–butylene–styrene (SEBS-g-MA) were prepared via melt compounding. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to evaluate the effects of the Org-MMT and SEBS-g-MA additions on the structure of nanocomposites. XRD traces showed that the characteristic (0 0 1) peak of the nanocomposites shifted to the lower angle region. Multi-layered stacks of clay platelets and independent exfoliated platelets were observed in TEM image. This implied that mixed intercalated and exfoliated structure were developed in the nanocomposites. The impact essential work of fracture (EWF) tests were used to evaluate the impact fracture toughness of the nanocomposites toughened with elastomer. The results showed that the SEBS-g-MA additions were beneficial in enhancing the essential and non-essential work of fracture of the nanocomposites.

Preparation and photocatalytic activity of titania particulate film with mesostructured silica as binder

TiO 2 (titania) particulate films with mesostructured silica (SiO 2) as binder were prepared by drying glass substrate coated with an aqueous mixture of titania particles, tetramethoxysilane (TMOS) and cetyltrimetylammonium bromide (CTAB) at appropriate temperature. X-ray diffraction (XRD) and IR absorption measurements on the obtained films revealed the formation of titania particles/silica composite thin film. XRD patterns at low angle region on these films indicated silica binder has well-ordered lamellar type mesostructure. These films show characteristic properties on both high absorption ability and photocatalytic activity to oxidative degradation of gaseous 2-propanol.

X-ray Diffraction and DOSY NMR Characterization of Self-Assembled Supramolecular Metallocyclic Species in Solution

Wide-angle X-ray scattering and diffusion NMR techniques have been used to obtain structural information on three self-assembled metallacyclic supramolecular complexes in solution: a rectangle, a triangle, and a three-diminsional cage. The low-angle region of the measured diffraction patterns and hydrodynamic radii calculations, determined from DOSY NMR experiments, suggest that the supramolecular assemblies retain their shape when dissolved in nitromethane. The experimental structure functions for the large-angle region have been analyzed, and the intramolecular contributions of the platinum-platinum interactions are discussed. These scattering measurements provide evidence that the supramolecular assemblies are not as rigid in solution as they are in the single crystal. Finally, by analysis of the radial distribution functions of the solutions, direct structural information (e.g., platinum-platinum intramolecular distances and coordination number) about the supramolecular assemblies has been obtained.

RAMAN, FTIR and PXRD studies of water in cinchoninum tetrachlorocadmate(II) hemipentahydrate and tetrachlorozincate(II) dihydrate compounds

Two transition metal (Cd(II) and Zn(II)) compounds with cinchonine, i.e. [(cinH 2)CdCl 4]·2.5H 2O and [(cinH 2)ZnCl 4]·2H 2O were studied, to explain the role of water molecules contained in their structure. FT-Raman and FTIR spectroscopy along with powder X-ray diffraction (PXRD) methods were applied to analyse structural changes induced in Zn(II) and Cd(II) derivatives by: (i) loosing crystallisation water as well as (ii) lowering temperature to 10 K. The PXRD patterns point to stronger changes in Cd(II)-cin structure framework on heating, confirmed by appearance of new reflections at low angle region. This fact may suggest differences in water bonding in Zn(II)-cin and Cd(II)-cin compounds. FT-Raman spectroscopy allow to indicate bands which characterise vibrations in which water molecules are involved, i.e. 1606 cm −1 and also to those which are disturbed by disappearance of the water, i.e. 3120, 3100 and 3077 cm −1. Redistribution of relative intensities in 1350–1400 cm −1 region, was a confirmation that Cd(II)-cin structure with doubly protonated cinchonine at N1 and N13 is a stable form. The observed changes in MIR spectra seem to be connected with the rearrangement of the hydrogen bond network and with the reorganisation of the cinchonine constituent moieties as a function of temperature.

Effects of non-standard neutrino interactions on MSW-LMA solution to the solar neutrino problem

Abstract We show that the non-standard neutrino interactions can play a role as subleading effect on the solar neutrino oscillations. We observe that very small flavor universality violations of order of 0.1–0.2 G F is sufficient to induce two phenomena: suppression of the ν e -Earth regeneration and a shift of the resonance layer in the Sun. We obtain these phenomena even in the absence of any flavor changing interactions. We discuss their consequences and confront with a global analysis of solar+KamLAND results. We conclude that a new compatibility region in the Δ m 2 ×tan 2 θ ⊙ , which we call very low large mixing angle region is found for Δ m 2 ∼10 −5 eV 2 and tan 2 θ ⊙ =0.45.

Effects of non-standard neutrino interactions on MSW-LMA solution to the solar neutrino problem

We show that the non-standard neutrino interactions can play a role as subleading effect on the solar neutrino oscillations. We observe that very small flavor universality violations of order of 0.1–0.2 GF is sufficient to induce two phenomena: suppression of the νe-Earth regeneration and a shift of the resonance layer in the Sun. We obtain these phenomena even in the absence of any flavor changing interactions. We discuss their consequences and confront with a global analysis of solar+KamLAND results. We conclude that a new compatibility region in the Δm2×tan2θ⊙, which we call very low large mixing angle region is found for Δm2∼10−5 eV2 and tan2θ⊙=0.45.