179 research outputs found
HEiDi: Single crystal diffractometer at hot source
The single crystal diffractometer HEiDi, which is operated by the Institute of Crystallography, RWTH Aachen University and JCNS, Forschungszentrum Jülich, is designed for detailed studies on structural and magnetic properties of single crystals using unpolarised neutrons and Bragg’s Law: 2dhklsinθ = λ (typically 0.55 Å <λ< 1.2 Å)
Breadmaking performance of protein enriched, gluten-free breads
9 pages, 3 figures, 5 tables.-- Published online 19 February 2008.-- The original publication is available at www.springerlink.comSoybean enriched, rice-based gluten-free breads were designed incorporating a structuring agent (hydroxypropylmethylcellulose, HPMC) and a processing aid (transglutaminase, TG). At dough level the effect of increasing amounts of soybean protein isolate (SPI), HPMC and water was studied in the Mixolab. Mixing and thermal characteristics showed the significant effect induced by water, soybean protein isolate, HPMC and TG, allowing the selection of the appropriate amounts for the breadmaking performance of enriched gluten-free breads. The single addition or in combination of 4% HPMC, 13% soybean and 1% TG produced significant changes in the physical properties of the rice-based gluten-free breads. The presence of SPI blended with rice flour produced a significant decrease in the specific volume of the bread, although this detrimental effect was partially counteracted by its combination with HPMC, decreasing also the crumb hardness. The micrographs of the crumb showed the beneficial effect of the HPMC, obtaining a more open aerated structure. Protein enriched, gluten-free breads can be obtained with a combination of SPI, HPMC and TG.This work was financially supported by Comisión Interministerial de Ciencia y Tecnología Project (MCYT, AGL2005-05192-C04-01) and Consejo Superior de Investigaciones Científicas (CSIC). C. Marco gratefully acknowledges the Ministerio de Educación y Ciencia for her grant.Peer reviewe
Ultra-high vacuum compatible induction-heated rod casting furnace
We report the design of a radio-frequency induction-heated rod casting
furnace that permits the preparation of polycrystalline ingots of intermetallic
compounds under ultra-high vacuum compatible conditions. The central part of
the system is a bespoke water-cooled Hukin crucible supporting a casting mold.
Depending on the choice of mold, typical rods have a diameter between 6 mm and
10 mm and a length up to 90 mm, suitable for single-crystal growth by means of
float-zoning. The setup is all-metal sealed and may be baked out. We find that
the resulting ultra-high vacuum represents an important precondition for
processing compounds with high vapor pressures under a high-purity argon
atmosphere up to 3 bar. Using the rod casting furnace, we succeeded to prepare
large high-quality single crystals of two half-Heusler compounds, namely the
itinerant antiferromagnet CuMnSb and the half-metallic ferromagnet NiMnSb.Comment: 5 pages, 4 figure
Neutron diffraction in gemology: Single-crystal diffraction study of brazilianite, NaAl3(PO4)(2)(OH)(4)
The chemical composition and the crystal structure of a gem-quality brazilianite from the Telírio pegmatite, near Linópolis, Minas Gerais, Brazil, [NaAl3(PO4)2(OH)4, a = 11.2448(5) Å, b = 10.1539(6) Å, c = 7.1031(3) Å, β = 97.351(4)°, V = 804.36(7) Å3, space group P21/n, Z = 4], have been reinvestigated by means of electron microprobe analysis in wavelength-dispersive mode, single-crystal X-ray and neutron diffraction. The chemical analysis shows that brazilianite from Telírio Claim approaches almost ideal composition. The neutron anisotropic structural refinement was performed with final agreement index R1 = 0.0290 for 211 refined parameters and 2844 unique reflections with Fo > 4σ(Fo), the X-ray refinement led to R1 = 0.0325 for 169 refined parameters and 2430 unique reflections with Fo > 4σ(Fo). The building-block units of the brazilianite structure consist of chains of edge-sharing AlO4(OH)2 and AlO3(OH)3 octahedra. Chains are connected, via corner-sharing, by P-tetrahedra to form a three-dimensional framework, with Na atoms located in distorted cavities running along [100]. Five independent H sites were located, here labeled as H(1), H(2a), H(2b), H(3), and H(4). The configuration of the OH groups, along with the complex hydrogen-bonding scheme, are now well defined. The O-H distances corrected for "riding motion" range between ~0.992 and ~1.010 Å, the O···O distances between ~2.67 and ~2.93 Å, and the O-H···O angles between ~151° and ~174°. The H(2a) and H(2b) are only ~1.37 Å apart and mutually exclusive (both with site occupancy factor of 50%). The differences between the crystal structure of brazilianite and wardite [ideally NaAl3(PO4)2(OH)4·2H2O] are discussed. This work fulfills the need for accurate crystal-chemical data for this gem mineral
Low-temperature properties of single-crystal CrB
We report the low-temperature properties of B-enriched single-crystal
CrB as prepared from high-purity Cr and B powder by a solid-state
reaction and optical float zoning. The electrical resistivity, ,
Hall effect, , and specific heat, , are characteristic of an
exchange-enhanced Fermi liquid ground state, which develops a slightly
anisotropic spin gap below . This observation is corroborated by the absence of a Curie dependence in
the magnetization for reported in the literature. Comparison of
with , where we infer lattice contributions from
measurements of VB, reveals strong antiferromagnetic spin fluctuations with
a characteristic spin fluctuation temperature
in the paramagnetic state, followed by a pronounced second-order mean-field
transition at , and unusual excitations around . The pronounced anisotropy of above is
characteristic of an easy-plane anisotropy of the spin fluctuations consistent
with the magnetization. The ratio of the Curie-Weiss to the Nel
temperatures, , inferred from the
magnetization, implies strong geometric frustration. All physical properties
are remarkably invariant under applied magnetic fields up to ,
the highest field studied. In contrast to earlier suggestions of local-moment
magnetism our study identifies CrB as a weak itinerant antiferromagnet
par excellence with strong geometric frustration.Comment: 15 pages, 9 figure
Бюджетный и коммерческий учёт оплаты труда, сравнительный анализ
Целью дипломной работы является провести исследования организации и учета заработной платы, изучить действующие системы и формы оплаты труда, документальное оформление оплаты труда, показать основные этапы начисления заработной платы, удержаний из заработной платы и выплат социального характера, провести анализ начисления заработной платы на конкретном предприятии.The purpose of the thesis is to conduct research on the organization and accounting of wages, to study the existing systems and forms of payment, documentation of wages, to show the main stages of payroll, deductions from wages and social benefits, to analyze the payroll at a particular enterprise
Domain redistribution and ferroelectric phase transition in SrTiO 3 under the influence of an electric field and mechanical stress
Low-temperature structural investigations of the frustrated quantum antiferromagnets Cs2CuCl(4-x)Br(x)
Powder X-ray diffraction (PXRD) and single-crystal neutron scattering were
used to study in detail the structural properties of the Cs2CuCl(4-x)Br(x)
series, good realizations of layered triangular antiferromagnets. Detailed
temperature-dependent PXRD reveal a pronounced anisotropy of the thermal
expansion for the three different crystal directions of the orthorhombic
structure without any structural phase transition down to 20 K. Remarkably, the
anisotropy of the thermal expansion varies for different , leading to
distinct changes of the geometry of the local Cu environment as a function of
temperature and composition. The refinement of the atomic positions confirms
that for x=1 and 2, the Br atoms occupy distinct halogen sites in the
[CuX4]-tetrahedra (X = Cl, Br). The precise structure data are used to
calculate the magnetic exchange couplings using density functional methods for
x=0. We observe a pronounced temperature dependence of the calculated magnetic
exchange couplings, reflected in the strong sensitivity of the magnetic
exchange couplings on structural details. These calculations are in good
agreement with the experimentally established values for Cs2CuCl4 if one takes
the low-temperature structure data as a starting point
- …