162 research outputs found

    Rashba Effect at Magnetic Metal Surfaces

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    We give experimental and theoretical evidence of the Rashba effect at the magnetic rare-earth metal surface Gd(0001). The Rashba effect is substantially enhanced and the Rashba parameter changes its sign when a metal-oxide surface layer is formed. The experimental observations are quantitatively described by ab initio calculations that give a detailed account of the near-surface charge density gradients causing the Rashba effect. Since the sign of the Rashba splitting depends on the magnetization direction, the findings open up new opportunities for the study of surface and interface magnetism.Comment: 4 Fig

    Driving magnetic order in a manganite by ultrafast lattice excitation

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    Optical control of magnetism, of interest for high-speed data processing and storage, has only been demonstrated with near-infrared excitation to date. However, in absorbing materials, such high photon energies can lead to significant dissipation, making switch back times long and miniaturization challenging. In manganites, magnetism is directly coupled to the lattice, as evidenced by the response to external and chemical pressure, or to ferroelectric polarization. Here, femtosecond mid-infrared pulses are used to excite the lattice in La0.5Sr1.5MnO4 and the dynamics of electronic order are measured by femtosecond resonant soft x-ray scattering with an x-ray free electron laser. We observe that magnetic and orbital orders are reduced by excitation of the lattice. This process, which occurs within few picoseconds, is interpreted as relaxation of the complex charge-orbital-spin structure following a displacive exchange quench - a prompt shift in the equilibrium value of the magnetic and orbital order parameters after the lattice has been distorted. A microscopic picture of the underlying unidirectional lattice displacement is proposed, based on nonlinear rectification of the directly-excited vibrational field, as analyzed in the specific lattice symmetry of La0.5Sr1.5MnO4. Control of magnetism through ultrafast lattice excitation has important analogies to the multiferroic effect and may serve as a new paradigm for high-speed optomagnetism.Comment: 10 pages manuscript, 4 figure

    КАЧЕСТВО ЖИЗНИ ПАЦИЕНТОВ С МЫШЕЧНО-ИНВАЗИВНЫМ РАКОМ МОЧЕВОГО ПУЗЫРЯ СТАДИИ Т2B−Т3А ПОСЛЕ ХИРУРГИЧЕСКОГО ЛЕЧЕНИЯ

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    The article represents the study of quality of life in patients with muscle-invasive bladder cancer stages T2b and T3a after surgery, depending on the operation type. The study was conducted using questionnaires EORTC QLQ-30 and FACT-BL. The best levels of quality of life were observed in patients after organ-saving treatment of muscle-invasive bladder cancer.Представлен материал по изучению качества жизни у пациентов с мышечно-инвазивным раком мочевого пузыря (РМП) стадии Т2b и Т3а после хирургического лечения в зависимости от вида оперативного пособия. Исследование проводилось с помощью опросников EORTC QLQ-30 и FACT-BL. Наилучшие показатели качества жизни наблюдаются среди пациентов после органосохраняющего лечения мышечно-инвазивного РМП

    ХАРАКТЕР РЕЦИДИВИРОВАНИЯ ПОСЛЕ ОРГАНОСОХРАНЯЮЩЕГО ОПЕРАТИВНОГО ЛЕЧЕНИЯ МЫШЕЧНО-ИНВАЗИВНОГО РАКА МОЧЕВОГО ПУЗЫРЯ

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    The article represents the study of frequency and nature of the recurrence and survival rate (common, oncology-specific, disease-free) after organ-saving surgery of patients with muscle-invasive bladder cancer stages T2b and T3a. Oncology-speсific and disease-free survival rates were much higher if full diagnosis of bladder mucosa, the adjuvant intravesical chemotherapy had been on pre-operative and intra-operative stages than in the absence of these diagnosis and therapy. Recurrentes of bladder cancer which appeared in the absence of diagnosis and combination therapy, statistically reliably occured at another location other than the zone of operation, stage of recurrentes and degree of differentiation of recurrents were less than the original tumor. This information confirms the existence of foci of cancer in situ which have not been identified on the diagnostic stage.Изучены частота, характер рецидивирования и показатели выживаемости (общей, онкоспецифической, безрецидивной) после органосохраняющего оперативного лечения мышечно-инвазивного рака мочевого пузыря (РМП) в стадии Т2b−Т3а. Выявлено, что онкоспецифическая и безрецидивная выживаемость при наличии полноценной диагностики слизистой мочевого пузыря на до- и интраоперационном этапах и при проведении адъювантной внутрипузырной химиотерапии намного выше, чем при отсутствии данных обследований и комбинированной терапии. Рецидивы РМП, возникающие при отсутствии обследования слизистой мочевого пузыря и адъювантной внутрипузырной химиотерапии, статистически достоверно возникают на другом месте, отличном от зоны операции, стадия рецидива и степень дифференцировки рецидива меньше, чем первоначальной опухоли, что подтверждает наличие очагов рака in situ, не выявленных на этапе диагностики

    Prediction of huge X-ray Faraday rotation at the Gd N_4,5 threshold

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    X-ray absorption spectra in a wide energy range around the 4d-4f excitation threshold of Gd were recorded by total electron yield from in-plane magnetized Gd metal films. Matching the experimental spectra to tabulated absorption data reveals unprecedented short light absorption lengths down to 3 nm. The associated real parts of the refractive index for circularly polarized light propagating parallel or antiparallel to the Gd magnetization, determined through the Kramers-Kronig transformation, correspond to a magneto-optical Faraday rotation of 0.7 degrees per atomic layer. This finding shall allow the study of magnetic structure and magnetization dynamics of lanthanide elements in nanosize systems and dilute alloys.Comment: 4 pages, 2 figures, final version resubmitted to Phys. Rev. B, Brief Reports. Minor change

    Manufacturing of Hybridomas-Producers of Monoclonal Anti-Bodies to Tularemia Agent Antigens

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    Carried out have been two experimental studies on hybridization of mouse myeloma cells and lymphocytes of BALB/c mice immunized with inactivated microbe Francisella tularensis cultures. As a result obtained have been hybridomas-producers of monoclonal antibodies (MAb) specific to the antigens of tularemia agent. Evaluated have been the prospects of its application for the detection of the agent under discussion using enzyme-linked immunoassay. Established is the fact that monoclonal antibodies produced by 31G1F10, 32E5D3, 35B11C8, 36C2F11 hybridomas make it possible to identify microbe cells of various tularemia agent strains when concentrated up to 0.5·106 mc/sm3, and do not interact with cultures of heterologous microorganisms when concentrated to 1.0·108 mc/sm3, which testifies to their specificity. These MAb are planned to be used for the construction of immune-enzyme and immune-chromatographic test-systems designed for tularemia agent detection

    Development of a technology for the preparation of a dry nutrient medium for anthrax vaccine production

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    Currently, submerged cultivation of the Bacillus anthracis STI-1 strain for live anthrax vaccine production requires liquid nutrient media, which have disadvantages of a short shelf life (no more than one month) and a narrow range of storage temperatures (2–8 °С). Dry media, in contrast, have a number of indisputable advantages: such media are transportable and easy to use, have a standard capability to retain properties, and can be stored without preservatives at 2–30 °С for 2–5 years. The aim of this work was to develop a technology for the preparation of a dry nutrient medium for anthrax vaccine production. Materials and methods: The study used the Bacillus anthracis STI-1 vaccine strain and a nutrient medium for its cultivation, containing a 70:30 mixture of an enzymatic digest of casein and a pre-processed corn extract solution. Drying of the nutrient medium was carried out on a spray-drying unit. The authors evaluated physicochemical parameters of experimental medium batches. The shelf life was determined by an accelerated stability study. The dry nutrient medium was used to produce a live anthrax vaccine. Quality attributes of the vaccine were assessed for compliance with regulatory requirements. Results: The authors developed the dry media production technology. According to it, the liquid nutrient medium is fed to the drying unit at a rate of 20–25 dm3/h. The spray air pressure is 0.02 MPa. Temperatures at the drying chamber inlet and outlet are 118–122 °С and 85–90 °С, respectively. The technology was used to obtain 3 experimental batches of the dry medium. The study results demonstrate that the technology is reproducible, and the tested quality attributes of experimental medium batches are consistent with the requirements. According to the accelerated stability study, the shelf life of the dry nutrient medium at 2–30 °С is at least 3 years. Experiments demonstrated the possibility of using the dry nutrient medium for live anthrax vaccine production. Critical quality attributes of the vaccine obtained with the medium met regulatory requirements. Conclusions: The developed technology allows for the production of a standard dry nutrient medium with a prolonged shelf life, which is convenient for live anthrax vaccine production

    Evolution of three-dimensional correlations during the photoinduced melting of antiferromagnetic order in La

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    Using time-resolved resonant soft x-ray diffraction, we measure the evolution of the full three-dimensional scattering volume of the antiferromagnetic superlattice reflection in the single-layer manganite La<sub>0.5</sub>Sr<sub>1.5</sub>MnO<sub>4</sub> on femtosecond time scales following photoexcitation. We find that the in-plane correlations are unchanged as a metastable state is entered, however there are subtle changes in the c-axis correlations. We observe a transient shift of the scattering ellipsoid along (00L) at very short times, and at longer time scales the short-range c-axis correlations are more robust than they are in equilibrium. Such results are not obtainable with any other techniques and hint at previously unresolved processes in the dynamics of photomelting in strongly correlated systems
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