Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 28
Filtrar
1.
Phys Rev Lett ; 131(25): 256504, 2023 Dec 22.
Artículo en Inglés | MEDLINE | ID: mdl-38181357

RESUMEN

An ultrasharp photoluminescence line intimately related to antiferromagnetic order has been found in NiPS_{3}, a correlated van der Waals material, opening prospects for magneto-optical coupling schemes and spintronic applications. Here we unambiguously clarify the singlet origin of this excitation, confirming its roots in the spin structure. Based on a comprehensive investigation of the electronic structure using angle-resolved photoemission and q-dependent electron energy loss spectroscopy as experimental tools we develop, in a first step, an adequate theoretical understanding using density functional theory (DFT). In a second step the DFT is used as input for a dedicated multiplet theory by which we achieve excellent agreement with available multiplet spectroscopy. Our Letter connects the understanding of the electronic structure and of optical processes in NiPS_{3} and related materials as a prerequisite for further progress of the field.

2.
Inorg Chem ; 52(24): 13974-83, 2013 Dec 16.
Artículo en Inglés | MEDLINE | ID: mdl-24266792

RESUMEN

Crystal structures of three new lithium copper borates, Li3CuB3O7, Li8Cu7B14O32, and Li2Cu9B12O28, and a new Li6CuB4O10 polymorph were solved by single-crystal X-ray diffraction. In all of the structures, the boron cations form BO3 triangles, which are connected with each other and with copper polyhedra only via corners in Li6CuB4O10 and Li3CuB3O7 and via both corners and edges in Li8Cu7B14O32 and Li2Cu9B12O28. The Li3CuB3O7 and Li8Cu7B14O32 compounds were synthesized as pure samples with only trace amounts of impurities; hence, their magnetic properties could be investigated and analyzed in terms of underlying magnetic couplings. Other compositions always represented multiphase mixtures. Li3CuB3O7 features infinite Cu,O chains formed by Cu2O6 units consisting of edge-shared CuO4 squares. Together with two apical oxygen atoms with long interatomic Cu-O distances of 2.7-2.8 Å, the Cu2O6 units form chains extended along the a axis. These pseudochains are responsible for strong anisotropic thermal expansion behavior. The temperature dependence of the magnetization between 4 and 380 K for Li3CuB3O7 could be fit well by a spin-dimer model. The magnetic susceptibility of Li8Cu7B14O32 showed a more complex temperature dependence, with two different Curie-Weiss regimes in the temperature range of 2-380 K.

3.
Chem Soc Rev ; 41(15): 5068-80, 2012 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-22491511

RESUMEN

Nanostructured materials lie at the heart of fundamental advances in efficient energy storage and/or conversion, in which surface processes and transport kinetics play determining roles. This review describes recent developments in the synthesis and characterization of composites which consist of lithium metal phosphates (LiMPO(4), M = Fe, Co, Ni, Mn) coated on nanostructured carbon architectures (unordered and ordered carbon nanotubes, amorphous carbon, carbon foams). The major goal of this review is to highlight new progress in using different three dimensional nanostructured carbon architectures as support for the phosphate based cathode materials (e.g.: LiFePO(4), LiCoPO(4)) of high electronic conductivity to develop lithium batteries with high energy density, high rate capability and excellent cycling stability resulting from their huge surface area and short distance for mass and charge transport.

4.
Anal Bioanal Chem ; 400(3): 691-6, 2011 May.
Artículo en Inglés | MEDLINE | ID: mdl-21225245

RESUMEN

For future Li-ion battery applications the search for both new design concepts and materials is necessary. The electrodes of the batteries are always in contact with electrolytes, which are responsible for the transport of Li ions during the charging and discharging process. A broad range of materials is considered for both electrolytes and electrodes so that very different chemical interactions between them can occur, while good cycling behavior can only be obtained for stable solid-electrolyte interfaces. X-ray photoelectron spectroscopy (XPS) was used to study the most relevant interactions between various electrode materials in contact with different electrolyte solutions. It is shown how XPS can provide useful information on reactivities and thus preselect suitable electrode/electrolyte combinations, prior to electrochemical performance tests.

5.
Inorg Chem ; 49(22): 10348-56, 2010 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-20964307

RESUMEN

The phase stability, crystal structure, and magnetic properties of perovskite-like nonstoichiometric Sr(2)CoIrO(6-δ) were studied. Oxygen deficiency can be well controlled and reversibly varied up to δ = 0.33. A single phase exists at least for partial oxygen pressures between 10(-5) and 1 bar at 1273 K, followed by phase decomposition at higher temperature with the elimination of metallic Ir and the formation of a new phase with approximately Sr(3)CoIrO(6) composition crystallizing in K(4)CdCl(6) structure type. The structural features of Sr(2)CoIrO(6-δ) are dependent on both temperature and oxygen content and were determined by synchrotron and neutron powder diffraction. Both the increasing amount of oxygen vacancies at constant temperature and increasing temperature at constant oxygen content result in the same higher crystal symmetry of Sr(2)CoIrO(6-δ): (1) The oxygen-stoichiometric phase Sr(2)CoIrO(6.00) is monoclinic (I2/m or P2(1)/n) at room temperature but cubic (Fm-3m) for Sr(2)CoIrO(5.67). (2) A sequence of phase transitions [Formula: see text] was observed for Sr(2)CoIrO(6.00) in air. All Sr(2)CoIrO(6-δ) compositions show weak ferromagnetism at low temperature with a canted but predominantly antiferromagnetic ground state. The magnetic ordering temperature decreases monotonously with increasing oxygen deficiency, while pronounced extrema are observed for the paramagnetic moment and the Curie-Weiss temperature at an oxygen deficiency δ ≈ 0.10, which corresponds to the P2(1)/n ↔ I2/m phase transformation.

6.
J Phys Chem A ; 114(51): 13362-9, 2010 Dec 30.
Artículo en Inglés | MEDLINE | ID: mdl-21133400

RESUMEN

The peculiarities of oxygen nonstoichiometry (δ) in tetragonal La(2-x)Sr(x)CuO(4-δ) solid solution with x(Sr) = 0.15-1.2 were studied by XRD, NPD, in situ high-temperature XPS, and chemical analysis. Temperature dependences of oxygen nonstoichiometry, δ = δ(T), were obtained for different Sr contents at 1 bar of O(2). Two types of charge compensation during replacement of lanthanum by strontium are discussed: an increase of the average copper oxidation state and a formation of oxygen vacancies. The average copper oxidation state V(Cu) exhibits a maximum of 2.32 at x(Sr) = 0.6, while δ increases with x(Sr). Oxygen vacancies are unambiguously located on the 4c site ({CuO(2)} plane) for compositions with different strontium contents, which electronic state is described by the O 2p core electron peak at about 531 eV. Thermal stability of the solid solution in a vacuum is associated with the extraction of practically the entire oxygen from CuO(2) layers and the formation of Cu(+) at least in the near-surface region. The higher average copper oxidation state after synthesis in the Sr-rich phases in comparison with the Sr-poor compositions prevents oxygen removal and the formation of Cu(+) and, therefore, stabilizes the structure during heating in a vacuum.

7.
Klin Lab Diagn ; (3): 14-8, 2010 Mar.
Artículo en Ruso | MEDLINE | ID: mdl-20734686

RESUMEN

The clinical laboratory study of 75 patients with type 2 diabetes mellitus (T2D) has shown that most of them have elevated immunoglobulin A and G levels, the diminished activity of neutrophiles, and higher C-reactive protein and 30% of the patients show non-physiological adaptation reactions: reactivation and stress. During these reactions, there are the most pronounced changes in the immunological status and in the level of acute phase protein. The rate of nonphysiological reactions increases, immunity deteriorates, and the activity of an inflammatory process is enhanced with the longer duration of T2D, grades 2 and 3 arterial hypertension, micro- and macroangiopathies, as well as with more evident hyperglycemia and triglyceridemia.


Asunto(s)
Adaptación Fisiológica , Diabetes Mellitus Tipo 2/inmunología , Proteínas de Fase Aguda/análisis , Proteína C-Reactiva/análisis , Diabetes Mellitus Tipo 2/complicaciones , Diabetes Mellitus Tipo 2/fisiopatología , Angiopatías Diabéticas/etiología , Angiopatías Diabéticas/inmunología , Femenino , Humanos , Hipertensión/complicaciones , Hipertensión/inmunología , Inmunoglobulina A/sangre , Inmunoglobulina G/sangre , Masculino , Persona de Mediana Edad , Neutrófilos/inmunología , Estrés Fisiológico
8.
Artículo en Ruso | MEDLINE | ID: mdl-18467992

RESUMEN

Data on postmortem examination of five patients deceased during Legionnaires' outbreak in town Verkhnyaya Pyshma are presented in the article. Feature of course of the disease was severe affection of the lungs with development of toxic shock. Pathomorphological picture in lungs was characterized by polymorphism, presence of shock reaction and ventilator-associated pneumonia (atelectases, distelectases, tracheobronchitis). In autopsy material from four fatal cases Legionella pneumophila serogroup 1 was detected. Causative agent of pneumonia was not determined in one fatal case although comparison of clinical and morphological characteristics of this case with other four cases as well as detection of Gram-negative bacillus in alveolar macrophages allowed to consider this case of pneumonia as caused by Legionella. In studied fatal cases postmortem diagnoses were ascertained in which main disease was bilateral pneumonia caused by Legionella pneumophila serogroup 1 complicated by toxic shock.


Asunto(s)
Infecciones Comunitarias Adquiridas/patología , Legionella pneumophila , Enfermedad de los Legionarios/patología , Pulmón/patología , Anciano , Anciano de 80 o más Años , Autopsia , Bronquitis/patología , Infecciones Comunitarias Adquiridas/epidemiología , Brotes de Enfermedades , Femenino , Humanos , Legionella pneumophila/aislamiento & purificación , Enfermedad de los Legionarios/epidemiología , Masculino , Persona de Mediana Edad , Atelectasia Pulmonar/patología , Federación de Rusia/epidemiología , Choque/patología , Traqueítis/patología
9.
Artículo en Ruso | MEDLINE | ID: mdl-18464555

RESUMEN

Chest X-ray is the most common and widely used diagnostic procedure. Chest X-ray is frequently performed not only due to lungs diseases but also in other organs' diseases which indirectly affects lungs. At present computer tomography (CT) which has high resolution becomes to be more and more important. As in other diagnostic method, the main aim of CT is to confirm or reject the presence of disease. During outbreak of pneumonia in town Verkhnyaya Pyshma (Sverdlovsk region), all patients with suspected legionellosis underwent chest X-ray in front and lateral views. In several cases, computer tomography was performed.


Asunto(s)
Brotes de Enfermedades , Legionelosis/diagnóstico por imagen , Neumonía/diagnóstico por imagen , Femenino , Humanos , Legionelosis/epidemiología , Pulmón/diagnóstico por imagen , Masculino , Neumonía/epidemiología , Federación de Rusia/epidemiología , Tomografía Computarizada por Rayos X
10.
Artículo en Ruso | MEDLINE | ID: mdl-18467991

RESUMEN

Data on organization and carrying out of preventive and antiepidemic measures in hospital during hospitalization of more than 197 patients with Pontiac fever and pneumonia caused by Legionella were presented. Directions and formats of work with medical personnel, including those invited from other medical institutions, as well as their information support were determined. Optimal choice of organizational, and educational technologies, as well as ways to control of compliance with implemented measures by the staff allowed to prevent cases of nosocomial infections in patients and medical personnel.


Asunto(s)
Infección Hospitalaria/prevención & control , Hospitales Urbanos/organización & administración , Control de Infecciones , Legionelosis/prevención & control , Personal de Enfermería/organización & administración , Humanos , Personal de Enfermería/educación , Federación de Rusia
11.
Artículo en Ruso | MEDLINE | ID: mdl-18464542

RESUMEN

Bacteriologic, serologic, and PCR tests of blood, sputum, serum and autopsy samples from 91 patients were performed during outbreak of pneumonia in town Verkhnyaya Pyshma in July-August 2007. Streptococcus pneumoniae was isolated from 20% of diagnostically meaningful samples of sputum and from 50% of autopsy samples. Diagnosis of Legionnaires' disease was confirmed in 48% of cases. It was shown that association of Streptococcus pneumoniae and Legionella pneumophila determined the affect during such pneumonia. Need for establishment of diagnostic procedure for patients with pneumonia including those caused by atypical agents was revealed.


Asunto(s)
Infecciones Comunitarias Adquiridas/diagnóstico , Enfermedad de los Legionarios/diagnóstico , Neumonía Neumocócica/diagnóstico , Streptococcus pneumoniae , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Infecciones Comunitarias Adquiridas/epidemiología , Comorbilidad , Brotes de Enfermedades , Humanos , Legionella pneumophila/genética , Legionella pneumophila/inmunología , Legionella pneumophila/aislamiento & purificación , Enfermedad de los Legionarios/epidemiología , Persona de Mediana Edad , Neumonía Neumocócica/epidemiología , Federación de Rusia/epidemiología , Streptococcus pneumoniae/genética , Streptococcus pneumoniae/inmunología , Streptococcus pneumoniae/aislamiento & purificación
12.
Artículo en Ruso | MEDLINE | ID: mdl-18464552

RESUMEN

Data on organization and carrying out of preventive and antiepidemic measures in hospital during mass hospitalization (> 190 cases) of patients with community-acquired pneumonia caused by Legionella pneumophila are presented. Experience of physicians-epidemiologists in determination of directions of work in hospital, procedures of interaction, extent and description of biosafety measures in order to prevent nosocomial spread of infection to patients and staff are described.


Asunto(s)
Control de Enfermedades Transmisibles , Infecciones Comunitarias Adquiridas/prevención & control , Brotes de Enfermedades , Hospitales Urbanos/organización & administración , Enfermedad de los Legionarios/prevención & control , Desinfección , Humanos , Profesionales para Control de Infecciones , Médicos , Federación de Rusia
13.
Artículo en Ruso | MEDLINE | ID: mdl-18464540

RESUMEN

The aim of the study was a comparative analysis of diagnostic value of different laboratoty methods conducted on the basis of results of examination of patients during Legionnaires' disease outbreak in town Verkhnyaya Pyshma. Retrospective analysis of laboratory data from 74 patients with diagnosis of Legionnaires' disease was performed. Complex of laboratory methods was used (polymerase chain reaction (PCR), enzyme immunoassay (EIA), immunochromatography). In group of patients with Legionnaires' disease, the highest proportion of positive results (73%) was obtained by the EIA determining total specific antibodies in urine. Determination of antigen in urine by immunochromatographic express-test yielded 52% of positive results. PCR testing of blood specimens yielded positive results in 65% of samples but was low specific, due to that in 19% of patients from control group false-positive results were obtained. Testing of 3 autopsy samples showed that all specimens contained DNA of the causative agent. Performed analysis allowed to recommend complex use of immunochromatographic express-test of antigen detection and identification of total specific antibodies by EIA during mass people examination.


Asunto(s)
Cromatografía de Afinidad , Técnicas para Inmunoenzimas , Legionella , Legionelosis/diagnóstico , Reacción en Cadena de la Polimerasa , Anticuerpos Antibacterianos/sangre , Anticuerpos Antibacterianos/orina , Antígenos Bacterianos/orina , ADN Bacteriano/análisis , ADN Bacteriano/genética , Reacciones Falso Positivas , Humanos , Legionella/genética , Legionella/inmunología , Legionelosis/sangre , Legionelosis/orina , Estudios Retrospectivos , Federación de Rusia , Sensibilidad y Especificidad
14.
Artículo en Ruso | MEDLINE | ID: mdl-18467993

RESUMEN

One of the key elements in epidemiologic control for infectious diseases is timely and active identification of contacts, which results in in-time hospitalization of patients that are needed it and allows to conduct educational work with the public. Measures for outpatient medical and preventive help in Legionella infection which were developed on the experience of termination of outbreak of pneumonia caused by Legionella in town Verkhnyaya Pyshma in July-August, 2007 are presented.


Asunto(s)
Brotes de Enfermedades , Legionelosis/prevención & control , Atención a la Salud/organización & administración , Conocimientos, Actitudes y Práctica en Salud , Hospitalización , Humanos , Control de Infecciones , Legionella , Federación de Rusia/epidemiología , Población Urbana
15.
Artículo en Ruso | MEDLINE | ID: mdl-18464556

RESUMEN

Data on organization of medical care during outbreak of Legionnaires' disease in July-August, 2007 in town Verkhnyaya Pyshma in Sverdlovsk region are presented. Special feature of this outbreak was spreading of infection in boundaries of the town with total population of 70,600 people. Results of organizational work of health authorities in order to provide timely and adequate medical care for patients with Legionnaires' disease on both outpatient and inpatient levels of care, conduction of preventive measures in foci of infection, coordination of interaction between different medical organizations and services are summarized in the article.


Asunto(s)
Infecciones Comunitarias Adquiridas/epidemiología , Brotes de Enfermedades , Hospitales Urbanos/organización & administración , Enfermedad de los Legionarios/epidemiología , Adulto , Niño , Preescolar , Infecciones Comunitarias Adquiridas/diagnóstico , Infecciones Comunitarias Adquiridas/microbiología , Notificación de Enfermedades , Desinfección , Humanos , Legionella pneumophila/clasificación , Legionella pneumophila/aislamiento & purificación , Enfermedad de los Legionarios/diagnóstico , Cuarentena , Federación de Rusia/epidemiología
16.
Dalton Trans ; 46(47): 16711, 2017 Dec 21.
Artículo en Inglés | MEDLINE | ID: mdl-29168859

RESUMEN

Correction for 'Composition-dependent charge transfer and phase separation in the V1-xRexO2 solid solution' by D. Mikhailova, et al., Dalton Trans., 2017, 46, 1606-1617.

17.
Dalton Trans ; 46(5): 1606-1617, 2017 Jan 31.
Artículo en Inglés | MEDLINE | ID: mdl-28091651

RESUMEN

The substitution of vanadium in vanadium dioxide VO2 influences the critical temperatures of structural and metal-to-insulator transitions in different ways depending on the valence of the dopant. Rhenium adopts valence states between +4 and +7 in an octahedral oxygen surrounding and is particularly interesting in this context. Structural investigation of V1-xRexO2 solid solutions (0.01 ≤ x ≤ 0.30) between 80 and 1200 K using synchrotron X-ray powder diffraction revealed only two polymorphs that resemble VO2: the low-temperature monoclinic MoO2-type form (space group P21/c), and the tetragonal rutile-like form (space group P42/mnm). However, for compositions with 0.03 < x ≤ 0.15 a phase separation in the solid solution was observed below 1000 K upon cooling down from 1200 K, giving rise to two isostructural phases with slightly different lattice parameters. This is reflected in the appearance of two metal-to-insulator transition temperatures detected by magnetization and specific heat measurements. Comprehensive X-ray photoelectron spectroscopy studies showed that an increased amount of Re leads to a change in the Re valence state from solely Re6+ at a low doping level (≤3 at% Re) via mixed-valence states Re4+/Re6+ for at least 0.03 < x ≤ 0.10, up to nearly pure Re4+ in V0.70Re0.30O2. Thus, compositions V1-xRexO2 with only one valence state of Re in the material (Re6+ or Re4+) can be obtained as a single phase, while intermediate compositions are subjected to a phase separation, presumably due to different valence states of Re.

18.
Eksp Med Morfol ; 18(1): 5-12, 1979.
Artículo en Búlgaro | MEDLINE | ID: mdl-436713

RESUMEN

The authors carried out a pharmacokynetic study on the Bulgarian preparation Tempidone in rats. They examined resorption, distribution and excretion of the preparation in urine, bile and feces of rat after venous and oral administration. The experiments were carried out on 207 white male rats of the Wistar strain, weighting from 160 to 180 gm. Blood samples were obtained at various intervals from the onset of venous administration of the preparation in a dose of 100 mg/kg of body weight. After oral administration of the dose of 125 mg/kg of body weight in addition to blood samples other samples from brain, liver, stomach and intestines (small and large) were obtained as well. Excretion of Tempidone through the bile was examined after intraperitoneal administration of 250 mg/kg of body weight. They proposed pharmakynetic models after venous and oral administration of Tempidone. The obtained results gave evaluation for the rate, with which the distribution processes in the organism of rats occurred. Pharmacologic action of Tempidone coinceded in time with the creation and support of effective plasma concentrations. The wide distribution and preservation of Tempidone in the tissues suggested that it underwent the so called tissue binding.


Asunto(s)
Piperidinas/farmacología , Piperidonas/farmacología , Absorción , Administración Oral , Animales , Relación Dosis-Respuesta a Droga , Inyecciones Intravenosas , Cinética , Masculino , Ratas , Factores de Tiempo , Distribución Tisular , Compuestos de Tosilo/farmacología , Triacetonamina-N-Oxil/análogos & derivados
19.
Eksp Med Morfol ; 17(1): 18-27, 1978.
Artículo en Búlgaro | MEDLINE | ID: mdl-639743

RESUMEN

The purpose of the present work is to describe the pharmacokynetic characteristics of the preparation Ehinopsine, which represents N-methyl-gamma-chinoline and is synthetised in NIHFI during 1965. The experiments were carried out on male rats of the strain Wistar with weight of 170 to 190. The authors examine in dynamics plasma and tissues after single intraperitonenal administration of a dose of 30 mg/kg of body weight, plasma after venous administration of 25 mg/kg of body weight and 100 mg/kg of body weight and plasma and tissues-after oral administration of 100 mg/kg of body weight. The excretion of the preparation was examined also in bile, urine and feces after oral administration and there were metabolites in urine. On the basis of the experimental data after oral and venous treatment the respective mathematical models of distribution were determined as well as the basic pharmacokynetic parameters, characterizing the behaviour of Ehinopsine in the organism of rats. The obtained results gave a picture for good resorption of the preparation, quick distribution, weak excretion and wide biotransformation in the organism of the experimental animals.


Asunto(s)
Quinolinas/farmacología , Administración Oral , Animales , Biofarmacia , Biotransformación , Bulgaria , Inyecciones Intraperitoneales , Inyecciones Intravenosas , Cinética , Masculino , Matemática , Plantas Medicinales , Quinolinas/sangre , Ratas , Factores de Tiempo
20.
Eksp Med Morfol ; 18(4): 229-34, 1979.
Artículo en Búlgaro | MEDLINE | ID: mdl-520273

RESUMEN

The authors investigated the pharmacokinetics of the pressor substance 5,8-dimetoxy-trans-2-/2-hydroxyethyl/-amino-3-hydroxy-1,2,3,4-tetrahydronaphthaline hydrochloride (1b), which possessed strong pressor action. Blood concentrations after venous administration in a dose of 1 mg/kg of body weight were determined by means of exctration spectrofluorometric method. The data complied with the biexponential equation, meeting the requirements of an open two-compartment model. There was a quick elimination of the substance from the central compartment, which correlated also with the data for quick disappearances of the effect on the arterial pressure.


Asunto(s)
Naftalenos/sangre , Tetrahidronaftalenos/sangre , Vasoconstrictores , Animales , Presión Sanguínea/efectos de los fármacos , Evaluación Preclínica de Medicamentos , Inyecciones Intravenosas , Cinética , Masculino , Conejos , Factores de Tiempo
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA