314 research outputs found
Raman and fluorescence contributions to resonant inelastic soft x-ray scattering on LaAlO/SrTiO heterostructures
We present a detailed study of the Ti 3 carriers at the interface of
LaAlO/SrTiO heterostructures by high-resolution resonant inelastic soft
x-ray scattering (RIXS), with special focus on the roles of overlayer thickness
and oxygen vacancies. Our measurements show the existence of interfacial Ti
3 electrons already below the critical thickness for conductivity and an
increase of the total interface charge up to a LaAlO overlayer thickness of
6 unit cells before it levels out. By comparing stoichiometric and oxygen
deficient samples we observe strong Ti 3 charge carrier doping by oxygen
vacancies. The RIXS data combined with photoelectron spectroscopy and transport
measurements indicate the simultaneous presence of localized and itinerant
charge carriers. However, it is demonstrated that the relative amount of
localized and itinerant Ti electrons in the ground state cannot be deduced
from the relative intensities of the Raman and fluorescence peaks in excitation
energy dependent RIXS measurements, in contrast to previous interpretations.
Rather, we attribute the observation of either the Raman or the fluorescence
signal to the spatial extension of the intermediate state reached in the RIXS
excitation process.Comment: 9 pages, 6 figure
Temperature dependent Eu 3d-4f X-ray Absorption and Resonant Photoemission Study of the Valence Transition in
We study the mixed valence transition ( 80 K) in
EuNi(SiGe) using Eu 3 X-ray absorption
spectroscopy (XAS) and resonant photoemission spectroscopy (RESPES). The
Eu and Eu main peaks show a giant resonance and the spectral
features match very well with atomic multiplet calculations. The spectra show
dramatic temperature ()-dependent changes over large energies (10 eV)
in RESPES and XAS. The observed non-integral mean valencies of 2.35
0.03 ( = 120 K) and 2.70 0.03 ( = 40 K) indicate homogeneous
mixed valence above and below . The redistribution between
Eu+ and Eu+ states is attributed to
a hybridization change coupled to a Kondo-like volume collapse.Comment: 4 pages, 3 figure
Совершенствование бизнес-процессов организации
Объектом исследования является ООО "СОФИТ". Предмет исследования-бизнес-процессы компании.
Цель работы: проанализировать бизнес-процессы организации и предложить практические методы их совершенствования.
В процессе исследования проводились сравнительный анализ и анализ по показателям результативности.
В результате исследования были предложены мероприятия по совершенствованию текущих бизнес-процессов.The object of the research is LLC "SOFIT". The subject of the research are company's business processes.
The purpose of the work is to analyse the business processes of the organisation and to offer practical methods to improve it.
In the course of the study, a comparative analysis and an analysis of performance indicators were carried out.
As a result of the study, measures were proposed to improve current business processes
Urinary proteome pattern in children with renal Fanconi syndrome
Background. The renal Fanconi syndrome (FS) is characterized by renal glucosuria, loss of electrolytes, bicarbonate and lactate, generalized hyperaminoaciduria and low-molecular-weight proteinuria. We studied the urinary low-molecular-weight proteome to identify excreted peptides indicative of a pathogenetic mechanism leading to tubular dysfunction. Methods. We established a urinary proteome pattern using capillary electrophoresis mass spectrometry (CE-MS) of 7 paediatric patients with cystinosis and 6 patients with ifosfamide-induced FS as the study group, and 54 healthy volunteers and 45 patients suffering from other renal diseases such as lupus nephritis (n = 8), focal segmental glomerulosclerosis (n = 27), minimal change disease (n = 7) and membranous glomerulonephritis (n = 3) as controls. Consequently, we conducted a blinded study consisting of 11 FS patients and 9 patients with renal disease other than FS. Additionally, we applied this pattern to 294 previously measured samples of patients with different renal diseases. Amino acid sequences of some marker proteins were obtained. Results. Specificity for detecting FS was 89% and sensitivity was 82%. The marker peptides constituting the proteome pattern are fragments derived from osteopontin, uromodulin and collagen alpha-1. Conclusions. CE-MS can be used to diagnose FS in paediatric patients and might be a future tool for the non-invasive diagnosis of FS. The reduced amount of the marker proteins osteopontin and uromodulin indicates loss of function of tubular excretion in all patients suffering from FS regardless of the underlying cause. In addition, the six different fragments of the collagen alpha-1 (I) chain were either elevated or reduced in the urine. This indicates a change of proteases in collagen degradation as observed in interstitial fibrosis. These changes were prominent irrespectively of the stages of FS. This indicates fibrosis as an early starting pathogenetic reason for the development of renal insufficiency in FS patient
Auger transition from orbitally degenerate systems: Effects of screening and multielectron excitations
We calculate Auger spectra given by the two-hole Green's function from
orbitally degenerate Hubbard-like models as a function of correlation strength
and band filling. The resulting spectra are qualitatively different from those
obtained from fully-filled singly degenerate models due to the presence of
screening dynamics and multielectron excitations. Application to a real system
shows remarkable agreement with experimental results leading to
reinterpretation of spectral features.Comment: To appear in Phy. Rev. Let
Evaluation of the zucker diabetic fatty (ZDF) rat as a model for human disease based on urinary peptidomic profiles
Representative animal models for diabetes-associated vascular complications are extremely relevant in assessing potential therapeutic drugs. While several rodent models for type 2 diabetes (T2D) are available, their relevance in recapitulating renal and cardiovascular features of diabetes in man is not entirely clear. Here we evaluate at the molecular level the similarity between Zucker diabetic fatty (ZDF) rats, as a model of T2D-associated vascular complications, and human disease by urinary proteome analysis. Urine analysis of ZDF rats at early and late stages of disease compared to age- matched LEAN rats identified 180 peptides as potentially associated with diabetes complications. Overlaps with human chronic kidney disease (CKD) and cardiovascular disease (CVD) biomarkers were observed, corresponding to proteins marking kidney damage (eg albumin, alpha-1 antitrypsin) or related to disease development (collagen). Concordance in regulation of these peptides in rats versus humans was more pronounced in the CVD compared to the CKD panels. In addition, disease-associated predicted protease activities in ZDF rats showed higher similarities to the predicted activities in human CVD. Based on urinary peptidomic analysis, the ZDF rat model displays similarity to human CVD but might not be the most appropriate model to display human CKD on a molecular level
Numerical study of linear and circular model DNA chains confined in a slit: metric and topological properties
Advanced Monte Carlo simulations are used to study the effect of nano-slit
confinement on metric and topological properties of model DNA chains. We
consider both linear and circularised chains with contour lengths in the
1.2--4.8 m range and slits widths spanning continuously the 50--1250nm
range. The metric scaling predicted by de Gennes' blob model is shown to hold
for both linear and circularised DNA up to the strongest levels of confinement.
More notably, the topological properties of the circularised DNA molecules have
two major differences compared to three-dimensional confinement. First, the
overall knotting probability is non-monotonic for increasing confinement and
can be largely enhanced or suppressed compared to the bulk case by simply
varying the slit width. Secondly, the knot population consists of knots that
are far simpler than for three-dimensional confinement. The results suggest
that nano-slits could be used in nano-fluidic setups to produce DNA rings
having simple topologies (including the unknot) or to separate heterogeneous
ensembles of DNA rings by knot type.Comment: 12 pages, 10 figure
Structure and dynamics of ring polymers: entanglement effects because of solution density and ring topology
The effects of entanglement in solutions and melts of unknotted ring polymers
have been addressed by several theoretical and numerical studies. The system
properties have been typically profiled as a function of ring contour length at
fixed solution density. Here, we use a different approach to investigate
numerically the equilibrium and kinetic properties of solutions of model ring
polymers. Specifically, the ring contour length is maintained fixed, while the
interplay of inter- and intra-chain entanglement is modulated by varying both
solution density (from infinite dilution up to \approx 40 % volume occupancy)
and ring topology (by considering unknotted and trefoil-knotted chains). The
equilibrium metric properties of rings with either topology are found to be
only weakly affected by the increase of solution density. Even at the highest
density, the average ring size, shape anisotropy and length of the knotted
region differ at most by 40% from those of isolated rings. Conversely, kinetics
are strongly affected by the degree of inter-chain entanglement: for both
unknots and trefoils the characteristic times of ring size relaxation,
reorientation and diffusion change by one order of magnitude across the
considered range of concentrations. Yet, significant topology-dependent
differences in kinetics are observed only for very dilute solutions (much below
the ring overlap threshold). For knotted rings, the slowest kinetic process is
found to correspond to the diffusion of the knotted region along the ring
backbone.Comment: 17 pages, 11 figure
X-ray absorption spectroscopy systematics at the tungsten L-edge
A series of mononuclear six-coordinate tungsten compounds spanning formal oxidation states from 0 to +VI, largely in a ligand environment of inert chloride and/or phosphine, has been interrogated by tungsten L-edge X-ray absorption spectroscopy. The L-edge spectra of this compound set, comprised of [W<sup>0</sup>(PMe<sub>3</sub>)<sub>6</sub>], [W<sup>II</sup>Cl<sub>2</sub>(PMePh<sub>2</sub>)<sub>4</sub>], [W<sup>III</sup>Cl<sub>2</sub>(dppe)<sub>2</sub>][PF<sub>6</sub>] (dppe = 1,2-bis(diphenylphosphino)ethane), [W<sup>IV</sup>Cl<sub>4</sub>(PMePh<sub>2</sub>)<sub>2</sub>], [W<sup>V</sup>(NPh)Cl<sub>3</sub>(PMe<sub>3</sub>)<sub>2</sub>], and [W<sup>VI</sup>Cl<sub>6</sub>] correlate with formal oxidation state and have usefulness as references for the interpretation of the L-edge spectra of tungsten compounds with redox-active ligands and ambiguous electronic structure descriptions. The utility of these spectra arises from the combined correlation of the estimated branching ratio (EBR) of the L<sub>3,2</sub>-edges and the L<sub>1</sub> rising-edge energy with metal Z<sub>eff</sub>, thereby permitting an assessment of effective metal oxidation state. An application of these reference spectra is illustrated by their use as backdrop for the L-edge X-ray absorption spectra of [W<sup>IV</sup>(mdt)<sub>2</sub>(CO)<sub>2</sub>] and [W<sup>IV</sup>(mdt)<sub>2</sub>(CN)<sub>2</sub>]<sup>2–</sup> (mdt<sup>2–</sup> = 1,2-dimethylethene-1,2-dithiolate), which shows that both compounds are effectively W<sup>IV</sup> species. Use of metal L-edge XAS to assess a compound of uncertain formulation requires: 1) Placement of that data within the context of spectra offered by unambiguous calibrant compounds, preferably with the same coordination number and similar metal ligand distances. Such spectra assist in defining upper and/or lower limits for metal Z<sub>eff</sub> in the species of interest; 2) Evaluation of that data in conjunction with information from other physical methods, especially ligand K-edge XAS; 3) Increased care in interpretation if strong π-acceptor ligands, particularly CO, or π-donor ligands are present. The electron-withdrawing/donating nature of these ligand types, combined with relatively short metal-ligand distances, exaggerate the difference between formal oxidation state and metal Z<sub>eff</sub> or, as in the case of [W<sup>IV</sup>(mdt)<sub>2</sub>(CO)<sub>2</sub>], add other subtlety by modulating the redox level of other ligands in the coordination sphere
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