bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous small-angle/wide-angle X-ray scattering and differential scanning calorimetry study of the effects of glycerol on hydrated monoolein
Authors: Abe Satoru , Takahashi Hiroshi
Published: April 2003

Monoolein is a natural amphiphilic molecule. Many applications of monoolein have been reported in different fields, for example, the crystallization of membrane protein in a bicontinuous cubic phase of monoolein-water systems, drug delivery systems using hydrated monoolein. Glycerol acts as a cryoprotectant. In order to get basic information for the discussion of the cryoprotective mechanism of glycerol, the effects of glycerol on the structure and phase behavior of hydrated monoolein were investigated by means of simultaneous small-angle X-ray scattering, wide-angle X-ray diffraction and differential scanning calorimetry measurements. We found that addition of glycerol increases the lamellar crystal-to-bicontinuous cubic phase transition temperature and reduces the lattice constants of the cubic phase. We discuss the interaction between glycerol and monoolein from the results obtained in this study.
Effect of precipitate size and dispersion on recrystallization behavior in Ti-added ultra low carbon steels
Authors: Shin E. J. , Seong B. S. , Han Y. S. , Hong K. P. , Lee C. H. , Kang H. J.
Published: April 2003

The effect of coiling temperature on precipitates and solid solution was investigated in P-free and P-added Ti-stabilized ultra low carbon steels. The volume fractions of the fine precipitates smaller than 60 nm were evaluated by using small-angle neutron scattering technique. The solute P was quantified from the lattice parameters obtained from neutron diffraction patterns. In the P-free steels, TiC and Ti4C2S2 with various sizes ranging from 5~60 nm were observed. In addition to these precipitates, FeTiP precipitates of a size exceeding 50 nm were also observed in the P-added steel. The amount of fine precipitates smaller than 10 nm and the concentration of solute P was higher in the samples coiled at low temperature. The recrystallization temperature increases if the coiling temperature decreases in both, P-free and P-added steels. The recrystallization temperature of P-free steels is lower than that of P-added steels. In the P-free steels, the pinning effect of fine precipitates played a key role for the retardation of the recrystallization. In the P-added steels, the retardation of recrystallization is due to both, the pinning effect of fine precipitates and the solute drag effect of P in solid solution.
Ultra-small-angle neutron scattering studies of artificial lattices
Authors: Jericha Erwin , Baron Matthias , Hainbuchner Martin , Loidl Rudolf , Villa Mario , Rauch Helmut
Published: April 2003

Ultra-small-angle neutron scattering (USANS) with the use of perfect silicon crystals provides a resolution of the order of 10−5 Å−1 in reciprocal space, which corresponds to μrad in scattering angles and μm structures in real space. From small-angle scattering by artificial lattices follows a unique test procedure for the related devices and techniques. Corresponding measurements were performed at the USANS facilities of the Atominstitut in Vienna and of the S18 instrument at the ILL. We observed diffraction patterns from samples being periodically structured in one and two dimensions. These measurements take advantage of the extended coherence function of the set-up and the high quality of the manufactured silicon sample lattices. Due to these characteristics up to 50 interference orders were obtained at the S18 instrument. Scattering from two-dimensional periodic structures was observed for different orientations of the sample which shows characteristic diffraction maps in reciprocal space.
Diffraction analysis of highly ordered smectic supramolecules of conjugated rodlike polymers
Authors: Knaapila M. , Torkkeli M. , Jokela K. , Kisko K. , Horsburgh L. E. , Pålsson L-O. , Seeck O. H. , Dolbnya I. P. , Bras W. , ten Brinke G. , Monkman A. P. , Ikkala O. , Serimaa R.
Published: April 2003

A small/wide-angle X-ray scattering and grazing incidence diffraction study of comb-shaped supramolecules of conjugated poly(2,5-pyridinediyl), acid dopant and hydrogen bonded amphiphilic side chains is reported. In solution, polymers are dissolved rodlike particles. When the side-chains are introduced, polymers self-assemble in hierarchic liquid crystals (LC). Diffraction patterns of aligned LC show h00, 020, and 004 reflections, and additional small-angle reflections along the polymer axis. A triangular correlation function indicating a very large correlation length is seen along the smectic axis. An aligned solid structure can be formed by cleaving side chains from the aligned LC.
Recent progress in the development of concave Fresnel lenses for neutrons
Authors: Adachi T , Ikeda K , Oku T. , Sakai K. , Suzuki S. , Suzuki J. , Shimizu H.M. , Littrell K.C. , Loong C.-K. , Lin W. , Guo J. , Mitsuishi N. , Morita S. , Ohmori H.
Published: April 2003

The performance of a Fresnel-type compound refractive lens for focusing cold neutrons was evaluated. The lens consists of 44 pieces of compound Fresnel-type refractive lenses made of MgF2 single crystals. The intensity profile of the diffracted neutrons measured over the wavelengths of 9–14 Å was compared with the results of numerical simulations. Good neutron transmission of 0.85 for 9 Å neutrons and a focal length of 3.4 m for 16 Å neutrons were achieved.
Development of a high-resolution scintillator-based area detector for neutrons
Authors: Sakamoto N. , Kiyanagi Y. , Sato S. , Sagehashi H. , Furusaka M. , Suzuki J. , Littrell K.C. , Loong C.K. , Gorin A. , Manuilov I. , Ryazantsev A. , Kuroda K. , Sakai K. , Tokanai F. , Adachi T. , Oku T. , Ikeda K. , Miyasaka H. , Suzuki S. , Morimoto K. , Shimizu H.M.
Published: April 2003

We applied a scintillator-based area detector to the neutron time-of-flight method by developing a new electronics system for this detector, which detector consists of a thin plate of ZnS(Ag)+6Li scintillator optically coupled to wavelength shifter. The spatial resolution was about 0.4mm which is consistent with a fiber width of 0.4 mm. The detection efficiency for thermal neutrons was about 6%. A good-resolution radiographic-image as a function of flight time was obtained.
Pressure dependence of thermal fluctuation effects on the order–disorder transition of diblock copolymer solutions
Authors: Miyazawa Masaaki , Takenaka Mikihito , Miyajima Tatsuya , Hashimoto Takeji
Published: April 2003

We have investigated the pressure dependence of the order-disorder transition behavior, which is characterized by the strength of thermal fluctuation effects and the order-disorder transition temperature (TODT), for compositionally nearly symmetric polystyrene-block-polyisoprene diblock copolymer solution and the bulk with the small-angle X-ray scattering method. In the solution, thermal fluctuation effects and TODT increases with pressure. On the other hand, in the bulk, TODT increases with pressure, while thermal fluctuations effects decrease with pressure. Concentration fluctuations between polymers and solvent are considered to cause the difference between these results for the solution and the bulk.
Complex microphase separation and microdomain structures in polyisoprene-block-poly(D8-styrene)-block-poly(vinyl methyl ether) triblock terpolymer
Authors: Yamauchi K. , Hasegawa H. , Hashimoto T. , Nagao M.
Published: April 2003

Microphase separation of a polyisoprene-block-poly(D8-styrene)-block-poly(vinyl methyl ether) triblock terpolymer were investigated by small-angle neutron scattering and small-angle X-ray scattering. At low temperature, poly(D8-styrene) (DPS) and poly(vinyl methyl ether) (PVME) are miscible but polyisoprene (PI) is immiscible with both DPS and PVME so that the terpolymer is separated into two microphases, i.e., the PI phase and the phase of DPS and PVME which are moleculary mixed. In the temperature range covered in this experiment, the segregation power between PI and DPS decreases with increasing temperature but that between DPS and PVME increases, while PVME remains immiscible with PI. The competing short-range interactions with the opposite temperature dependences result in a complex but novel MS behavior and a change of the microdomain-structure with temperature as discussed in the text.
A new high pressure cell with sapphire windows for small-angle neutron scattering
Authors: Pépy G. , Baroni P.
Published: April 2003

The design and the construction of a cell for the study of the conformation and the structure of liquid crystal polymers under pressure is complex because of the high viscosity of these materials and the use of an external magnetic field to achieve a macroscopic alignment. We have developed a system reaching 1500 bar at 420 K, completely amagnetic, including a small leakproof inner cell sample container with a flexible wall and a larger outer cell resistant to high pressure, with sapphire windows allowing a 8 mm diameter neutron beam aperture, with scattering angles up to 14°. This cell is also equipped with a double sample volume, in order to measure sample volume changes by a differential method.
Small- and wide-angle elastic light scattering study of fibrin structure
Authors: De Spirito M. , Arcòvito G. , Papi M. , Rocco M. , Ferri F.
Published: April 2003

We show how small- and wide-angle elastic light scattering (q ~ 0.03-30 μm-1) can be used to quantitatively characterize the structure of polymeric gels made of semi-flexible entangled fibers. We applied the technique to the study of fibrin gels grown from the polymerization of fibrinogen (FG) macromolecular monomers following activation by the enzyme thrombin (TH), at different concentrations and under different physical-chemical conditions of the gelling solution. Our findings show that the gel can be imagined as a random network of fibers of size d and density ρ, entangled together to form densely packed blobs of mass fractal dimension Dm and average size ξ, which may overlap by a factor η and exhibit a long-range order. Provided that d ≥ 50-100 nm, all of the above parameters can be recovered by the use of a global fitting function developed by us on the basis on the proposed gel model. When the fibers are thinner (d < ~50 nm), only the fiber mass/length ratio μ ~ ρ d
 2 can be retrieved instead of d and ρ. Our data confirm and quantify the major changes in the gel structure that can be obtained by varying either the salt concentration of the solution and/or the molar ratio TH/FG. Gels formed in Tris-HCl 50 mM/NaCl 150 mM, pH 7.4 and TH/FG = 0.01 are characterized by relatively small, fairly branched (D
m ~ 1.4-2.0) fibers with a mass/length ratio independent of concentration. On reducing the TH/FG ratio, the fibers become increasingly thicker, with d ~ 90 nm at TH/FG = 10-5. When the salt concentration is reduced to NaCl 100 mM (TH/FG = 0.01) the fibers are less branched (D
m ~ 1.2-1.4), but much thicker, with μ increasing by an order of magnitude. These effects are quantitatively analyzed and discussed.
A combined small-angle neutron and X-ray scattering study of block copolymers micellisation in supercritical carbon dioxide
Authors: Lo Celso Fabrizio , Triolo Alessandro , Triolo Fabio , Thiyagarajan Pappannan , Amenitsch Heinz , Steinhart Milos , Kriechbaum Manfred , DeSimone Joseph M. , Triolo Roberto
Published: April 2003

Small angle neutron and X-ray scattering (SANS and SAXS) are used to investigate the monomer–aggregate transition of fluorocarbon–hydrocarbon diblock copolymers in supercritical carbon dioxide. SANS data are analyzed using a polydisperse sphere core–shell model. Synchrotron SAXS data have been collected by profiling the pressure at different temperatures, and critical micellization densities have been obtained for a series of diblock solutions. Finally pressure jump experiments, combined with synchrotron SAXS, have revealed two steps in the dynamics of the formation of the aggregates.
Time-of-flight implementation of an ultra-small-angle neutron scattering instrument
Authors: Carpenter J.M. , Agamalian M. , Littrell K.C. , Thiyagarajan P. , Rehm Ch.
Published: April 2003

We report calculations describing the Bonse-Hart ultra-small-angle neutron scattering (USANS) instrument with triple-bounce Si channel-cut crystals, which show that significant gains in Q-resolution and neutron flux can be achieved using multiple high-order Bragg reflections. These reflections become usable only after combining the Bonse-Hart and time-of-flight (t-o-f) techniques, thus this variant of the USANS camera needs a pulsed neutron source. We demonstrate that t-o-f USANS instruments installed, for example, at the SNS water moderator will improve the current state of the art. Through the use of multiple wavelengths, these will provide means to detect multiple scattering effects.
Analysis of potassium bubble inclusions in sintered tungsten wires
Authors: Len Adél , Harmat Péter , Pépy Gerard , Rosta László , Schade Peter
Published: April 2003

The tungsten wire used as incandescent coils in light sources requires extreme high-temperature creep resistance. After uniaxial thermomechanical treatment it fulfills these requirements. The heat treatment of the wires causes the spheroidisation of the elongated potassium filled bubbles with vanishing anisotropy in the small angle scattering patterns. The tungsten wires from different stages of the heat treatment were measured by small-angle neutron scattering (SANS). We have followed the morphology changes of the potassium bubble inclusions inside the tungsten matrix.
Spin-echo small-angle neutron scattering to study particle aggregates
Authors: Krouglov Timofei , Kraan Wicher H. , Plomp Jeroen , Rekveldt M. Theo , Bouwman Wim G.
Published: April 2003

A new method to measure spin-echo small-angle neutron scattering using π-flipping magnetised foils has been realised. This method makes it possible to measure in real space structural feature up to length scales of 2.5 μm. Measurements on concentrated colloidal systems reveal directly the evidence for short-range ordering.
Small-angle neutron scattering investigation of plastically deformed stainless steel
Authors: Lebedev Vassily , Didenko Vitaly , Lapin Alexander , Konoplev Kir , Orlova Diana , Török Gyula , Rétfalvi Eszter
Published: April 2003

The microstuctural evolution of plastically deformed steels has been studied by small-angle neutron scattering at ambient temperature in the range of momentum transfer q = (4π/λ)sin(θ/2) = 0.01–5 nm−1 where λ is neutron wavelength and θ is the scattering angle. Samples of austenite stainless steels were pulled on a standard bench to cause a plastic deformation, S = 0–60%, up to the fracture of the material. As a result of the deformation an increase of an order of magnitude was observed in the scatterred intensity I(q)~1/[1+(qRC
)2](6-D

s
)/2. The analysis of the I(q) distribution has shown the surface fractal nature of the observed nano-scale structures. The evolution of internal surface via intensive growth of pores (size RC
~20–40 nm) was found and a linear decrease of the surface fractal dimension 2.9≥Ds
(S)≥2.1 was observed. These findings can be used to design the fracture criteria for materials of industrial application.
Recent experiments on a small-angle/wide-angle X-ray scattering beam line at the ESRF
Authors: Bras W. , Dolbnya I.P. , Detollenaere D. , van Tol R. , Malfois M. , Greaves G.N. , Ryan A.J. , Heeley E.
Published: April 2003

Recent results using a new combined small-angle/wide-angle X-ray scattering (SAXS/WAXS) beam line at the European Synchrotron Radiation Source (ESRF) will be presented. This beam line is specifically designed to be able to handle complicated sample environments required to perform time-resolved experiments mimicking processing conditions used in material science. Besides the attention that has been given to the interfacing of these sample environments to the beam line data acquisition system also the developments in detector technology will be discussed. The influence that a high count rate and low noise WAXS detector can have on the accuracy of experimental results in polymer crystallisation will be shown. It is shown that it is feasible to detect crystalline volume fractions as low as 10-3-10-4 in polymeric systems.
Depletion-induced colloidal crystals at a wall characterised by small-angle X-ray diffraction
Authors: Xian X. , Petukhov A.V. , Snel M. M. E. , Dolbnya I.P. , Aarts D.G.A.L. , Vroege G.J. , Lekkerkerker H.N.W.
Published: April 2003

Silica photonic colloidal crystals on a flat glass substrate have been grown using the depletion attraction induced by nonadsorbing polymers. The dried samples have been characterised with high-resolution synchrotron small-angle X-ray diffraction and their surface topography has been studied by atomic force microscopy. The presence of long-range ordered crystals with a thickness as large as 90 planes is demonstrated. However, on some places the films are polycrystalline and contain disordered regions.
Structural characterization of undoped and Sb-doped SnO2 thin films fired at different temperatures
Authors: Rizzato Alessandro P. , Santilli Celso V. , Pulcinelli Sandra H. , Craievich Aldo F.
Published: April 2003

SnO2 thin films were obtained by the sol-gel method starting from inorganic precursor solutions. In this work, we compare the structure of undoped and Sb-doped SnO2 films prepared by dip-coating. The films were deposited on quartz substrates and then fired at different temperatures ranging from 383 up to 1173 K. The density and the thickness of the films were determined by X-ray reflectivity (XRR) and their porous nanostructure was characterized by grazing-incidence small angle X-ray scattering (GISAXS). XRR results corresponding to undoped and Sb-doped samples indicate a monotonous decrease in film thickness when they are fired at increasing temperatures. At same time, the apparent density of undoped samples exhibits a progressive increase while for Sb-doped films it remains invariant up to 973 K and then increases for T = 1173 K. Anisotropic GISAXS patterns of both films, Sb-doped and undoped, fired above 573 K indicate the presence of elongated pores with their major axis perpendicular to the film surface. For all firing temperatures the nanopores in doped samples are larger than in undoped ones. This suggests that Sb-doping favours the pore growth hindering the film densification. At the highest firing temperature (1173 K) this effect is reversed.
Small-angle X-ray scattering and neutron reflectivity studies of Langmuir–Blodgett films of copper tetra-tert-butyl-azaporphyrines
Authors: Valkova L. , Menelle A. , Borovkov N. , Erokhin V. , Pisani M. , Ciuchi F. , Carsughi F. , Spinozzi F. , Pergolini M. , Padke R. , Bernstorff S. , Rustichelli F.
Published: April 2003

Langmuir-Blodgett (LB) films of tetra-tert-butyl-substituted copper azaporphyrines, namely phthalocyanine (CuPc'), tetra-3-nitro-phthalocyanine (CuPc*) and porphyrazine (CuPaz'), are studied by small-angle scattering technique. Two kinds of systems are under investigation: first, the CuPc'/Cd-stearate-d
35 superlattices; second, the LB films of CuPc', CuPc* and CuPaz' doped with benzene-d
6. X-ray diffraction patterns of the superlattices exhibit bilayer structural units indicating existence of not only 1D but also 3D nano-aggregates of CuPc'. The neutron reflectivity study on the films heavily doped with benzene-d
6 indicates that π-deficiency and size of the azaporphyrine nuclei favor interactions between the nano-aggregates.
Small-angle X-ray scattering investigations of n-aliphatic alcohol film deposited on porous ZrO2
Authors: Pikus S. , Olszewska E. , Kalinowska S.
Published: April 2003

The small-angle scattering (SAXS) method can be and has already been used to investigate the electron density profile at phase boundaries. It has therefore become more and more frequently employed in the characterization of physical properties of organic films deposited on porous material surfaces. In the following paper, several hydrated and dehydrated porous zirconium oxide (ZrO2) samples covered with different amounts of dodecanol, bromododecanol, hexadecanol, heptadecanol or octadecanol have been examined using the SAXS method. Significant differences in the Porod plots of hydrated and dehydrated samples were observed. These differences suggest considerable differences in the alcohol molecule orientation on the two different kinds of surfaces. The presented results confirm that the SAXS method can be used in the determination of the structure of the organic phase deposited on the porous surface. It can also be observed that for the alcohol/ZrO2 system the Ruland-Vonk formula has limited usefulness with regard to the determination of the thickness of a deposited organic film.
Formation of α-ω(4,7,10,13-pentaoxa-16-azacyclooctadecane) hexadecane micelles in aqueous solution – effect of HCl addition
Authors: Caponetti Eugenio , Chillura-Martino Delia , Pedone Lucia
Published: April 2003

The structure of aggregates of a new bolaform surfactant [α-ω (4,7,10,13-pentaoxa-16-azacyclooctadecane) hexadecane] in neat aqueous solution has been investigated by small-angle neutron scattering. Preliminary data analysis unequivocally indicates that globular micelles are formed. This finding has been confirmed by the analysis of data obtained upon addition of hydrochloric acid. The observed significant reduction of micelle aggregation number has been attributed to the peculiar complexing ability of the two aza-crown ether units in the surfactant molecule; this is in line with information inferred from the complexation of ions into the non alkylated azacrown ethers. As a consequence of hydrogen ion uptake into the aza-crown ether unit, the partial ionization of surfactant causes a decrease in the micelle dimension that follows the increased repulsion among head groups.
Structural effects of macrocyclic compounds and their partition in sodium dodecylsulphate aqueous solutions
Authors: Chillura-Martino Delia , Caponetti Eugenio , Pedone Lucia
Published: April 2003

The partition of 1,4,7,10,13,16-esaoxacyclooctadecane (18C6), 4,7,13,16-tetraoxa-1,10-diazacyclooctadecane (2.2), 2,5,8,11,14,17-esaoxabicyclo[16.4.0]dicosane (B18C6) and 2,5,8,15,18,21-esoxatricyclo[20.4.0.09.14]esacosane (Cy218C6) in sodium dodecyl sulfate (SDS) aqueous solutions and their effect on the structure of surfactant aggregates has been investigated by small-angle neutron scattering. Results from data analysis have shown that by increasing macrocycle concentration the SDS micelles dimensions reduce for all systems investigated. At the same time information on macrocycles partition between the micellar and the continuous phase have been obtained. It was found that an appreciable portion of macrocyclic compounds is located in micellar aggregates; in particular, the amount of B18C6 and Cy218C6 results larger than that of 18C6 and 2.2. It was found that 18C6 and 2.2 molecules interact with charged surface of SDS micelles only via complexes formation between the sodium ions and the macrocycles. B18C6 and Cy218C6 interact either via complexes formation with the charged surface or with hydrophobic region inside the micelle, as a consequence of the presence of hydrophobic substituents. It was concluded that Cy218C6 fraction present inside the micelles is located in the core, while the B18C6 fraction is located in the palisade.
Structure and dispersion of carbon nanotubes
Authors: Schaefer Dale W. , Brown Janis M. , Anderson David P. , Zhao Jian , Chokalingam Kumar , Tomlin David , Ilavsky Jan
Published: April 2003

Small-angle light scattering and ultra small-angle X-ray scattering are used to assess the morphology of single-walled (SWNTs) and multi-walled carbon nanotubes (MWNTs). For MWNTs, a power-law scattered-intensity profile with a slope of –1.08 is consistent with the rod-like morphology. For SWNTs, however, scattering profiles characteristic of rod-like morphology are not observed on any length-scale from 1 nm to 50 μm. Rather, disordered objects are found that we identify as a network of carbon "ropes" enmeshed with polyelectrolyte dispersants. The effectiveness of polyelectrolyte dispersants is assessed using small-angle light scattering in conjunction with exposure to ultrasound. In the presence of an anionic polyelectrolyte, sonication can assist dispersion of both SWNTs and MWNTs. In the presence of a cationic agent, however, sonication can induce aggregation. SWNTs respond differently to ultrasound depending on whether residual synthesis catalyst is present. Four dispersants are studied, of which sodium polystyrene sulfonate is the most effective and polyallylamine hydrochloride is the least effective.
Photoluminescence properties and size distribution in laser synthesized Si nanopowders for optoelectronic devices
Authors: Botti S. , Coppola R. , May R. P. , Valli M.
Published: April 2003

Small-angle neutron scattering (SANS) and transmission electron microscopy (TEM) have been used to investigate the correlation between photoluminescence properties and particle size distributions in laser synthesized Si nanopowders, of interest for application in optoelectronics. The Si nanoparticle volume distributions obtained from the SANS data are in good agreement with the TEM histogram for particle diameters ranging between 30 and 200 Å approximately. Furthermore the SANS data confirm that, as it is known from photoemission spectra, in the case of highly luminescent powders a secondary distribution of particles ranging between 10 and 20 Å approximately (hardly visible by TEM) is present. Finally the SANS data analysis suggests that tiny inhomogeneities (5-10 Å in diameter), possibly micropores which may have relevant consequences on material performance, are also present in all the investigated samples.
Polymer dynamics from large to small scales
Authors: Richter D.
Published: April 2003

This lecture reviews quasielastic small-angle neutron scattering experiments exploring the dynamics of polymer melts. Starting from the entropy driven Rouse dynamics, I address its limitation to larger and smaller scales. On the large scale side neutron spin echo spectroscopy reveals the single chain dynamic structure factor and the self correlation function of a spatially confined chain in accordance with the reptation concept and shows that contour length fluctuations limit the chain confinement on the time scale of local reptation. Towards shorter distances it is shown that intrachain dissipation processes are the leading mechanism limiting Rouse motion.
Fatigue behaviour of industrial polymers – a microbeam small-angle X-ray scattering investigation
Authors: Roth Stephan V. , Burghammer Manfred , Ferrero Claudio , Diethert Alexander , Müller-Buschbaum Peter
Published: April 2003

The results of a microbeam small-angle X-ray scattering investigation performed at ID13/ESRF on the machine fatigue induced by short-term high force bending of an industrial polystyrene sample are presented. A clear indication of craze formation in the deformation zone is seen. For this zone the results suggest a model of cylindrical voids, their radii following a lognormal distribution. Furthermore, the craze's orientation shows a locally varying angular distribution around the axis normal to the force direction.
A swollen gel phase of DPPC aqueous solution with small amount of ethanol observed at moderate pressure and temperature
Authors: Seto Hideki , Nobutou Hidekazu , Yamada Norifumi L. , Takeda Takayoshi , Ihara Daisuke , Nagao Michihiro , Inoue Katsuaki
Published: April 2003

In order to clarify effects of pressure on phospholipids, small-angle neutron scattering and X-ray scattering experiments on an aqueous solution of dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) with small amount of ethanol were carried out. At moderate temperature and pressure (41 ≤ T ≤ 60°C and 10 ≤ P ≤ 80 MPa), among a fluid lamellar (Lα) phase, a ripple gel (Pα′) phase and an interdigitated gel (LβI) phase, we have found a new phase with a single peak at around Q = 0.06 Å−1. This phase was characterized to be a swollen gel phase from the data analysis. The kinetics of the phase transition to the LβI phase was investigated, and the relaxation was much slower than the transition to the other bilayer structures.
Gelation and drying of weakly bonded silica-PPO nanocomposites
Authors: Chaker Juliano Alexandre , Dahmouche Karim , Santilli Celso Valentim , Pulcinelli Sandra Helena , Craievich Aldo
Published: April 2003

Silica-poly(oxypropylene) (PPO) nanocomposites containing PPO with weak physical bonds between the organic (PPO) and inorganic (silica) phases were obtained by the sol-gel procedure. Three precursor sols containing silica and PPO with molecular weights of 1000, 2000 and 4000g/mol were prepared. The structure changes during the whole sol-gel process, i. e. sol formation, sol-gel transition and gel aging and drying were investigated in situ by small angle X-ray scattering (SAXS). The experimental SAXS curves corresponding to sols and wet gels containing PPO of molecular weight 1000g/mol indicate that the aggregates formed during the studied process are fractal objects. Close to the sol-gel transition and during gel aging the fractal dimension is D=2.5. A clearly different structure evolution occurs in samples prepared with PPO with molecular weights 2000 and 4000 g/mol. Our SAXS results indicate the presence of two coexisting and well-defined structure levels, one of them corresponding to small silica clusters and the other to large silica aggregates. These two levels remain along the whole transformation. The SAXS curves of all dry samples are similar to those of the corresponding wet gels suggesting that no significant changes at nanoscopic scale occur during the drying process.
Bilayer structure of ganglioside/cholesterol mixed system in the presence of Ca2+
Authors: Hayakawa Tomohiro , Hirai Mitsuhiro
Published: April 2003

We employed small-angle X-ray scattering measurement using synchrotron radiation to study structural properties of monosialoganglioside (GM1)/cholesterol (chol) mixtures in aqueous dispersions, in the presence of 0–50 mM CaCl2. Various molar ratios of GM1/chol were examined from 1:0 to 1:5. Without CaCl2 the radius of gyration (Rg
) of the aggregate increased linearly with increasing cholesterol content up to GM1/chol = 1/1. At cholesterol content above GM1/chol = 1/1, Rg
of the aggregate was almost constant, and a sharp diffraction peak at q = 0.18 Å−1, characteristic of cholesterol monohydrate crystals, was observed, suggesting the solubility limit of cholesterol in GM1 aggregates is about GM1/chol = 1/1. For the samples containing cholesterol of GM1/chol = 1/0.6 and above, the diffraction patterns showed a set of peaks that correspond to ~85 Å periodic lamellar structures in the presence of CaCl2 at concentrations higher than ~10 mM. The observed lamellar peak positions and the intensity ratio of the lamellar peaks (1st–4th) was not changed by the addition of CaCl2 up to 100 mM, demonstrating once formed multilayered structure of GM1/chol was not altered under the present conditions. Electron density profiles for this GM1/chol bilayer were obtained. The Ca2+-induced vesicle-to-lamellar phase separation of this system was found to be highly reversible by the Ca2+ chelation with ethylenediamine-tetraacetic acid.
Evaluation and improvements of the Rigaku imaging plate reader (R-Axis IV++) for the use in synchrotron X-ray solution scattering
Authors: Fujisawa Tetsuro , Nishikawa Yukihiro , Yamazaki Hideto , Inoko Yoji
Published: April 2003

The commercial imaging plate (IP) system, R-AXIS IV++ (RIGAKU Co., Japan) is an IP detector integrated with a read-out system. We evaluated it and made some improvements for R-AXIS IV++ to optimise it for the use of synchrotron X-ray solution scattering measurements. Rigorously controlling self-decay of stored images on the IP, a maximum 5% decrease in sensitivity was observed by changing the end time for IP erasure to the start time of exposure. By replacing standard IP material with another commercial material that gives a slower fading period, the decrease disappeared. It suggested that not only the self-decay of stored intensity, but also the relaxation of the IP was important in a quick measurement cycle (ca. 5 min). After these improvements were made, we compared its suitability for solution scattering with other detectors. We found scattering profiles amenable to quantitative analysis. However, in wide scattering regions with low signal strength, its dynamic range is still very sensitive to measuring conditions.
Grazing incidence small-angle X-ray scattering and diffraction study of the resistance of Mo implanted Si wafer after annealing
Authors: Lee Chih-Hao , Qiu Chui-Zhang , Yu Kuan-Li , Liang Jenq-Horng , Tsai Chun-Tse , Lin Ming-Zhe
Published: April 2003

Grazing-incidence small-angle X-ray scattering and X-ray diffraction were used to probe the particle size and distribution of MoSi2 in a Mo ion implanted Si(100) wafer at 1073 K after different annealing times. The sheet resistance of the sample decreases at the beginning of annealing due to the recovery of defects and then increases due to the growth of larger and separated particles. The particle size of MoSi2 determined by the grazing incidence small angle X-ray scattering is larger than that determined by the in-plane wide angle X-ray diffraction, which might indicate that the MoSi2 particle consists of a larger amount of disordered components or is a cluster of several smaller well-ordered grains.
From Pt molecules to nanoparticles: in-situ (anomalous) small-angle X-ray scattering studies
Authors: Haubold H.-G. , Vad T. , Waldöfner N. , Bönnemann H.
Published: April 2003

Anomalous small-angle X-ray scattering was employed to monitor in situ the formation of colloidal Pt particles by the reaction of Pt(acac)2 and Al(CH3)3 in solution. An intermediate complex molecule was found to decompose to form stable Pt particles of 1.2 nm diameter with a monomodal particle size distribution. A network like correlation in the particle positions tends to build up by organic spacer molecules between stabilizing aluminum–organic shells.
Low-resolution structure of immunoglobulins IgG1, IgM and rheumatoid factor IgM-RF from solution X-ray scattering data
Authors: Volkov Vladimir V. , Lapuk Viktor A. , Kayushina Renata L. , Shtykova Eleonora V. , Varlamova Elena Yu. , Malfois Mark , Svergun Dmitri I.
Published: April 2003

Low-resolution structures of immunoglobulins IgG, IgM and rheumatoid factor IgM-RF in solution were analyzed using synchrotron radiation small-angle X-ray scattering and the macromolecular shapes were restored ab initio from the scattering data. The shape of IgG agrees well with the distorted Y-type crystallographic model but has a swollen appearance reflecting flexibility of the molecule in solution. The structures of pentameric IgM and IgM-RF were reconstructed assuming a five-fold symmetry. The IgM displays a flat star-like shape with observable F(ab)2 regions. The overall shape of the IgM-RF is similar to that of the IgM but with distinctly asymmetric F(ab)2 regions. This result agrees with the earlier observed functional dissimilarity of the Fab fragments in the rheumatoid factor and points to their structural dissimilarity.
Evaluation of three algorithms for ab initio determination of three-dimensional shape from one-dimensional solution scattering profiles
Authors: Takahashi Yoshikazu , Nishikawa Yukihiro , Fujisawa Tetsuro
Published: April 2003

In recent years, several methods for determining ab initio three-dimensional shape from solution scattering have been reported. In order to clarify the common and unique features of these programs, we verified the stability and convergence of three major programs, 'dammin', 'saxs3d' and 'dalai_ga', for experimental data. Two different types of samples were prepared: troponin-C and denatured apomyoglobin. With all of the three programs, the stability of the models and fitting among different runs increased as the diameters of the packing spheres were reduced in the region larger than 4Å. In the case of troponin-C, the models obtained always bore a striking resemblance irrespective of different runs of three algorithms. The averaged model coincided with the averaged structure of multiple nuclear magnetic reasonance models. In the case of denatured apomyoglobin, the best models from different algorithms also have similar features. These results suggest that if the molecule contains highly mobile portions, the resulting model corresponds to the averaged structure.
Effect of pH on the nanostructure of an amphiphilic carbosilane/methacrylic acid block copolymer at air/water interface
Authors: Mouri Emiko , Matsumoto Kozo , Matsuoka Hideki
Published: April 2003

The nanostructure of a monolayer of the ionic amphiphilic diblock copolymer, poly(1,1-diethylsilacyclobutane)-block-poly(methacrylic acid) (poly(Et2SB-b-MAA)) with different MAA chain lengths on water, was investigated at various pH by in-situ X-ray reflectometry. The monolayer nanostructure was similar in acidic and neutral conditions, but significantly different on the subphase of pH10. With the long MAA polymer a dense carpet layer was detectable, but the carpet/brush structure in the monolayer was not observed. The short MAA chain sample on the subphase of pH10 had an Et2SB layer in monolayer explicitly thicker than that in an acidic or neutral condition at the same surface pressure. The differences in monolayer nanostructure can be attributed to the difference in ionization condition of carboxylic groups in the MAA chain.
Grazing-incidence small-angle X-ray scattering and X-ray diffraction from magnetic clusters obtained by Co + Ni sequential ion implantation in silica
Authors: Maurizio C. , Longo A. , Martorana A. , Cattaruzza E. , D'Acapito F. , Gonella F. , de Julian C. , Mattei G. , Mazzoldi P. , Padovani S. , Boesecke P.
Published: April 2003

We present a structural investigation on Co-Ni alloy nanoclusters obtained by sequential ion implantation in silica slides. The study is based on small angle X-ray scattering for obtaining the cluster size distribution and volume fraction and on X-ray diffraction for nanocrystalline structures, both performed in grazing incidence mode to enhance the cluster signal. A systematic comparison with cluster size distribution obtained from transmission electron microscopy points out the potential of the technique for investigating these composite glasses. The nanocrystal structure turns out to depend on the relative Co/Ni dose: the ccp structure is preferred at low Ni content, while the hcp structure predominates when increasing the Co content.
Viscoelastic effects in dynamics of concentration fluctuations in dynamically asymmetric polymer blends
Authors: Takenaka Mikihito , Takeno Hiroyuki , Hashimoto Takeji , Nagao Michihiro
Published: April 2003

Relaxation processes of the concentration fluctuations induced by a rapid pressure change were investigated for a dynamically asymmetric polymer blend (deuterated polybutadiene (DPB) / polyisoprene (PI)) with a composition of 50/50 by weight in one phase region by using time-resolved small-angle neutron scattering. The theoretical analysis yielded the wave-number q-dependence of Onsager kinetic coefficient which is characterized by a q
-2-dependence at qξ
ve >1 with the characteristic length ξ
ve being much larger than radius of gyration of DPB or PI. The estimated ξ
ve agrees well with that calculated using the theory by Doi & Onuki, which takes into account viscoelastic effects.
Effect of added organic solvent on interaction parameters of poly(N-isopropylacrylamide) in aqueous solution
Authors: Shimizu Shigeru , Seyama Takahiro , Sekine Ryohei , Kurita Kimio
Published: April 2003

Semi-dilute solutions of poly(N-isopropylacrylamide) in aqueous solution of tetrahydrofuran and n-butyl alcohol were measured by small-angle X-ray scattering method just below the lower critical solution temperature. From anglular dependence of the scattered intensity we determined the correlation length. The binary and ternary interaction parameters were evaluated from concentration dependence of the correlation length. The contribution of the segment-segment interactions to the entropy and the enthalpy were calculated from the temperature dependence of the cluster integrals. It has been found that both values are positive and the enthalpy increases with increasing amount of added organic solvent and reaches a maximum for each system. After the maximum those values decrease with increasing amount of added solvent e.g. in the case of 1-propanol-water mixed solvent system.
Small-angle neutron scattering study of droplet density dependence of the water-in-oil droplet structure in a ternary microemulsion
Authors: Nagao Michihiro , Seto Hideki , Shibayama Mitsuhiro , Yamada Norifumi L.
Published: April 2003

Droplet density, ϕ, dependence of the water-in-oil droplet structure of microemulsion was investigated by means of small-angle neutron scattering (SANS) at room temperature in a ternary system consisting of AOT (Aerosol-OT; dioctyl sulfosuccinate sodium salt), water, and n-decane. SANS profiles from 2 different contrast samples of the bulk contrast (AOT/D2O/C10H22) and of the film contrast (AOT/D2O/C10D22) were collected. By introducing a relative form factor as the ratio of scattering functions of the bulk and film contrast samples, we evaluated the ϕ dependence of the shape and size of droplets without the influence of the structure factor, S(Q). The mean radii of droplet core and shell were constant, while the polydispersity index decreased for ϕ ≤ ϕ
* ≃ 0.62. The evaluated structure factors S(Q) from the bulk-contrast samples were in good agreement with those from the film contrast. From the ϕ dependence of S(Q), we confirmed that the droplet density fluctuations were dominant at low-ϕ regime and the inter-droplet correlations at high-ϕ regime. The crossover concentration of these two regimes was estimated to be about 0.25. It is demonstrated that this relative form factor method is quite useful for SANS experiments.
Complementarity of small-angle neutron and X-ray scattering methods for the quantitative structural and dynamical specification of dendritic macromolecules
Authors: Kuklin Alexander I. , Ozerin Alexander N. , Islamov Akhmed Kh. , Muzafarov Aziz M. , Gordeliy Valentin I. , Rebrov Eugeniy A. , Ignat'eva Galina M. , Tatarinova Elena A. , Mukhamedzyanov Ruslan I. , Ozerina Lyudmila A. , Sharipov Eugeniy Yu.
Published: April 2003

The structural characteristics of polycarbosilane dendrimers with different molecular architecture were determined in solutions by small angle neutron and X-ray scattering. The same linear dimensions were sized up for the dendrimers both in benzene and chloroform. A solvent molecules penetration inside dendrimer structure in amount up to 30 vol.% was found from the comparison of the partial and effective scattering volume for the dendrimers in solution.
Small-angle X-ray scattering reveals hollow nanostructures in ι- and κ-carrageenan/surfactant complexes
Authors: Shtykova Eleonora V. , Shtykova Jr Evgenia V. , Volkov Vladimir V. , Konarev Petr V. , Dembo Alexander T. , Makhaeva Elena E. , Ronova Inga A. , Khokhlov Alexej R. , Reynaers Harry , Svergun Dmitri I.
Published: April 2003

Complexes of polyelectrolyte gels with oppositely charged surfactants form ordered polymer matrices with unique structure properties, which can be used in a wide range of medical, chemical and physical applications. Ordered matrices made of natural components are of special interest for medical and biological purposes. In the present study, self-organised complexes of native ι- and κ-carrageenans formed with oppositely charged cetylpyridinium chloride (CPC) are prepared and structurally characterised using small-angle X-ray scattering (SAXS). Starting from the molar ratio CPC/(charge of carrrageenan) of 0.2, the carrageenan gel shrinks and ordered motifs in its internal structure are formed. The internal order in the sample is reflected by the Bragg peaks in the scattering patterns which permit to compute periodicity and characteristic sizes of the ordered regions. Moreover, strong central scattering appears and the calculated fractal dimensions indicate that these regions are organised in well defined clusters. The periodicity of the ordered motifs computed from the Bragg peaks in the scattering patterns corresponds to the width of the surfactant bilayer (about 4.0 nm) for all the complexes. The crystallite size ranges from 25 nm to 40 nm depending on the type of carrageenan and on the amount of CPC. A model of the ordered fragments is proposed whereby the carrageenan/surfactant bilayers are regularly packed at the walls of hollow cylindric clusters with the outer radius of about 8 nm and height 40 nm. More detailed ab initio models indicate that these particles are formed by bent worm-like substructures with the cross-section coinciding to the thickness of the carrageenan/CPC bilayer. Thanks to a higher charge density per monomer, ι-carrageenans form more regular structures than κ-carrageenans.
Nanochannels in track-etched membranes
Authors: Pépy Gérard , Balanzat Emmanuel , Jean Bruno , Kuklin Aleksandr , Sertova Nadejda , Toulemonde Marcel
Published: April 2003

Track membranes are prepared by irradiation by energetic heavy ions. They are then etched by a suitable chemical solution, which creates uniform, nearly monodisperse channels. Small-angle X-ray scattering by the nanochannels gives typical patterns. New experimental protocol and data treatment allow one to obtain information about the channel diameter and dispersion, wall thickness and roughness.
Small-angle scattering on soft matter with dynamical asymmetry
Authors: Koizumi Satoshi
Published: April 2003

By employing small-angle neutron scattering, we investigated the mixing behavior in a quiescent state or under a shear flow on a miscible polymer mixture of deuterated polystyrene and poly(vinylmethylether). This polymer mixture uniquely shows the following behaviors in the intermediate temperature range between the two glass transition temperatures; (i) due to a large difference in glass transition temperatures, dynamical asymmetry or a difference of mobilities is enhanced upon temperature decrease, and (ii) the rheological relaxation becomes much slower than the concentration fluctuations determined by thermodynamics (gel-like limit). These two factors play an important role in the generation of a stress field and suppress small-angle scattering in a quiescent state. Under a shear flow, the stress imbalance enhanced by the dynamical asymmetry causes a butterfly pattern or shear-induced phase separation in the q-range of small-angle neutron scattering.
Small-angle X-ray scattering study of poly(ethylene-oxide) and styrene based ionomers blends
Authors: Ślusarczyk Cz. , Suchocka-Gałaś K. , Fabia J. , Włochowicz A.
Published: April 2003

Small-angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) were used to determine the miscibility and the morphology of blends of poly(ethylene-oxide) (PEO) and styrene-acrylic acid (S-AA) copolymers neutralized with alkali metals (Na+, Li+). In this study, we investigated the effects of blend composition and the content of ionic groups in amorphous ionomers on the segregation of amorphous component. It was found that PEO is partially miscible with styrene based ionomers due to the ion-dipole interactions. These interactions reduce mobility of PEO chains and hence, they are responsible for the decrease of crystallinity and the thickness of PEO lamellar crystals. SAXS revealed that ionomers segregated interfibrillarly during the crystallization process of PEO.