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71.
Lukas Spree Fupin Liu Volker Neu Marco Rosenkranz Georgios Velkos Yaofeng Wang Sandra Schiemenz Jan Dreiser Pierluigi Gargiani Manuel Valvidares Chia-Hsiang Chen Bernd Büchner Stanislav M. Avdoshenko Alexey A. Popov 《Advanced functional materials》2021,31(48):2105516
The chemical functionalization of fullerene single molecule magnet Tb2@C80(CH2Ph) enables the facile preparation of robust monolayers on graphene and highly oriented pyrolytic graphite from solution without impairing their magnetic properties. Monolayers of endohedral fullerene functionalized with pyrene exhibit magnetic bistability up to a temperature of 28 K. The use of pyrene terminated linker molecules opens the way to devise integration of spin carrying units encapsulated by fullerene cages on graphitic substrates, be it single-molecule magnets or qubit candidates. 相似文献
72.
Rapid and phase pure synthesis of microporous copper silicate (CuSH–1Na) with 12-ring channel system
Phase pure sample of the microporous copper silicate CuSH–1Na has been obtained by simplified hydrothermal method without using additives (H2O2 and Na2HPO4). Ion exchange of Na+ by Cs+, Ca2+ and Sr2+ ions showed that the structure can suffer partial replacement of the charge compensating cations. Ion exchange with Cs+ resulted in distinct dehydration while the ion exchange with Sr2+ increased the total amount of water. Water content in the Ca-exchanged sample is comparable to the as-synthesized sodium phase. Raman spectroscopy revealed that the divalent cations as Ca2+ and Sr2+ induce stronger local structural deformations than the monovalent Cs+. These structural changes have been also followed by the refined lattice distortions. Magnetic analyses showed that CuSH–1Na presents a very weak ferromagnetic interaction along the Cu2+ chains with a nearly vanishing Curie–Weiss temperature. This magnetic coupling is associated with super-super-exchange interactions through Cu–Na–O–Na–Cu paths. Antiferromagnetic coupling, attributed to inter-chains super-super-exchange interactions, competes with the ferromagnetic one and prevails at the lowest temperature. 相似文献
73.
Jianqiu Guo Yu Yang Balaji Raghothamachar Michael Dudley Stanislav Stoupin 《Journal of Electronic Materials》2018,47(2):903-909
The presence of lattice strain in n-doped 4H-SiC substrate crystals grown by a physical vapor transport method can strongly influence the performance of related power devices that are fabricated on them. Information on the level and the variation of lattice strain in these wafer crystals is thus important. In this study, a non-destructive method is developed based on synchrotron double-crystal x-ray topography to map lattice strains in 4H-SiC wafers. Measurements are made on two 4H-SiC substrate crystals—one is an unprocessed commercial wafer while the other was subject to a post-growth high-temperature heat treatment. Maps of different strain components are generated from the equi-misorientation contour maps recorded using synchrotron monochromatic radiation. The technique is demonstrated to be a powerful tool in estimating strain fields in 4H-SiC crystals. Analysis of the strain maps also shows that the normal strain components vary much more significantly than do the shear/rotation components, indicating that lattice dilation/compression rather than lattice tilt is the major type of deformation caused by both the incorporation of nitrogen dopants and the nucleation of basal plane dislocations. 相似文献
74.
Stoupin S Shvyd'ko Y Shu D Khachatryan R Xiao X DeCarlo F Goetze K Roberts T Roehrig C Deriy A 《The Review of scientific instruments》2012,83(2):023105
We report on design and performance of a high-resolution x-ray monochromator with a spectral bandwidth of ΔE(X) ? 1.5 meV, which operates at x-ray energies in the vicinity of the backscattering (Bragg) energy E(H) = 13.903 keV of the (008) reflection in diamond. The monochromator is utilized for high-energy-resolution diffraction characterization of diamond crystals as elements of advanced x-ray crystal optics for synchrotrons and x-ray free-electron lasers. The monochromator and the related controls are made portable such that they can be installed and operated at any appropriate synchrotron beamline equipped with a pre-monochromator. 相似文献
75.
Silicon nanowires (Si NWs), one-dimensional single crystalline, have recently drawn extensive attention, thanks to their robust applications in electrical and optical devices as well as in the strengthening of diamond/SiC superhard composites. Here, we conducted high-pressure synchrotron diffraction experiments in a diamond anvil cell to study phase transitions and compressibility of Si NWs. Our results revealed that the onset pressure for the Si I-II transformation in Si NWs is approximately 2.0 GPa lower than previously determined values for bulk Si, a trend that is consistent with the analysis of misfit in strain energy. The bulk modulus of Si-I NWs derived from the pressure-volume measurements is 123 GPa, which is comparable to that of Si-V NWs but 25% larger than the reported values for bulk silicon. The reduced compressibility in Si NWs indicates that the unique wire-like structure in nanoscale plays vital roles in the elastic behavior of condensed matter. 相似文献
76.
Konorov SO Glover CH Piret JM Bryan J Schulze HG Blades MW Turner RF 《Analytical chemistry》2007,79(18):7221-7225
Embryonic stem cells (ESC), derived from preimplantation embryos, are defined by their ability to both self-renew and differentiate into all of the cells and tissues of a mature animal. Efforts to develop methods for in vitro culture of ESC for research or eventual therapeutic applications are hampered by the lack of rapid, nondestructive assays for distinguishing ESC from other (differentiated) cells within a growing culture. Coherent anti-Stokes Raman scattering (CARS) microscopy is shown here to be a sensitive and nondestructive method for identifying mouse ESC based on selective observation of specific molecular vibrations believed to be spectroscopic markers indicating the differentiated vs undifferentiated states of such cells. The nonlinear nature of CARS also permits imaging with subcellular resolution, potentially offering a means by which chemical changes accompanying the early stages of differentiation may be associated with certain intracellular compartments (e.g., nucleus, cytoplasm, membranes). A novel exposure/collection configuration is described, which yields high collection efficiency and low interference from nonresonant background components. 相似文献
77.
Efficient time-resolved coherent anti-Stokes Raman scattering (CARS) of atmospheric nitrogen and ethanol trapped in a nanoporous silica aerogel matrix is demonstrated. Silica aerogel hosts are attractive for analytical CARS spectroscopy due to their high porosity/low density, low refractive index, and low scattering cross-section. Differences between the resonant and nonresonant parts of the nonlinear optical susceptibilities lead to much longer relaxation times for analytes compared to the matrix. Time-resolved CARS can then be used to obtain a nearly background-free measurement at characteristic vibrations of the analyte. These results demonstrate the potential of this approach for rapid, sensitive, background-free analyses of analytes entrapped in the aerogel pores, which may be advantageous for some environmental, chemical, and biological sensing applications. 相似文献
78.
Investigation on the thermal‐hygral behaniour of bricks with canity filling by recycling meterials. In the investigation project was examined whether bricks with simple cavity structure have a higher heat resistance by use of a heat insulation material filling in the cavities. The insulation material is a recycled product made of polystyrene and wood covered and bonded with cement. The influence of the configuration and thickness of the perforated bricks with vertical perforations and the geometry of the cavities of the brick on the thermal moisture states was evaluated. For investigation of the thermal resistance and the heat transmission coefficients were used the simulation program THERM, that considered the heat transportation through conduction in the brick fragments and the transport mechanisms conduction, convection and radiation in the airfilled cavities. The software package WUFI 2D was employed for the investigation of moisture transfer in the bricks. The investigations showed that the composite brick insulation stone has a thermal resistance twice as high as the initial brick. The moisture states can be partially in the brick more than 80 % humidity. This load is estimated as uncritical because the wooden particles are covered with cement slime. 相似文献
79.
Martin Klein Mria Csbnyeiov Stanislav
iaran
ubo Daniovi
Ivan Varga 《International journal of molecular sciences》2021,22(20)
The regeneration of a diseased heart is one of the principal challenges of modern cardiovascular medicine. There has been ongoing research on stem-cell-based therapeutic approaches. A cell population called telocytes (TCs) described only 16 years ago largely contributed to the research area of cardiovascular regeneration. TCs are cells with small bodies and extremely long cytoplasmic projections called telopodes, described in all layers of the heart wall. Their functions include cell-to-cell signaling, stem-cell nursing, mechanical support, and immunoregulation, to name but a few. The functional derangement or quantitative loss of TCs has been implicated in the pathogenesis of myocardial infarction, heart failure, arrhythmias, and many other conditions. The exact pathomechanisms are still unknown, but the loss of regulative, integrative, and nursing functions of TCs may provide important clues. Therefore, a viable avenue in the future modern management of these conditions is TC-based cell therapy. TCs have been previously transplanted into a mouse model of myocardial infarction with promising results. Tandem transplantation with stem cells may provide additional benefit; however, many underresearched areas need to be addressed in future research before routine application of TC-based cell therapy in human subjects. These include the standardization of protocols for isolation, cultivation, and transplantation, quantitative optimization of TC transplants, cost-effectivity analysis, and many others. 相似文献
80.
Atherosclerosis is one of the most important problems in modern medicine. Its high prevalence and social significance determine the need for a better understanding of the mechanisms of the disease’s development and progression. Lipid metabolism and its disorders are one of the key links in the pathogenesis of atherosclerosis. Lipids are involved in many processes, including those related to the mechanoreception of endothelial cells. The multifaceted role of lipids in endothelial mechanobiology and mechanisms of atherogenesis are discussed in this review. Endothelium is involved in ensuring adequate vascular hemodynamics, and changes in blood flow characteristics are detected by endothelial cells and affect their structure and function. 相似文献