Стан збереження та проблеми охорони культурної спадщини на Путивльщині

In a 2010 paper Aziz, Chergui and colleagues observe fluorescence yield (FY) detected X-ray absorption spectra that are concentration-dependent and show both dips and peaks. In this comment I will show that all observed spectral features are a consequence of the relative ratio of background and edge emission, combined with energy-dependent X-ray emission decay channels

Особенности социальной ответственности малых и средних предприятий

Рассмотрены особенности деятельности малых и средних предприятий, их отличия от крупных предприятий, особенности и проблемы развития социальной ответственности малого и среднего бизнеса в Украине.Розглянуто особливості діяльності малих і середніх підприємств, їх відмінності від великих підприємств, особливості та проблеми розвитку соціальної відповідальності малого і середнього бізнесу в Україні.The paper examines features of small and middle enterprises activities and their distinction from big enterprises. The problems concerning development of social responsibility of small and middle business in Ukraine are also considered in the article

Determination of total x-ray absorption coefficient using non-resonant x-ray emission

An alternative measure of x-ray absorption spectroscopy (XAS) called inverse partial fluorescence yield (IPFY) has recently been developed that is both bulk sensitive and free of saturation effects. Here we show that the angle dependence of IPFY can provide a measure directly proportional to the total x-ray absorption coefficient, µ(E). In contrast, fluorescence yield (FY) and electron yield (EY) spectra are offset and/or distorted from µ(E) by an unknown and difficult to measure amount. Moreover, our measurement can determine µ(E) in absolute units with no free parameters by scaling to µ(E) at the non-resonant emission energy. We demonstrate this technique with measurements on NiO and NdGaO3. Determining µ(E) across edge-steps enables the use of XAS as a non-destructive measure of material composition. In NdGaO3, we also demonstrate the utility of IPFY for insulating samples, where neither EY or FY provide reliable spectra due to sample charging and self-absorption effects, respectively

A PKC-Dependent Recruitment of MMP-2 Controls Semaphorin-3A Growth-Promoting Effect in Cortical Dendrites

There is increasing evidence for a crucial role of proteases and metalloproteinases during axon growth and guidance. In this context, we recently described a functional link between the chemoattractive Sema3C and Matrix metalloproteinase 3 (MMP3). Here, we provide data demonstrating the involvement of MMP-2 to trigger the growth-promoting effect of Sema3A in cortical dendrites. The in situ analysis of MMP-2 expression and activity is consistent with a functional growth assay demonstrating in vitro that the pharmacological inhibition of MMP-2 reduces the growth of cortical dendrites in response to Sema3A. Hence, our results suggest that the selective recruitment and activation of MMP-2 in response to Sema3A requires a PKC alpha dependent mechanism. Altogether, we provide a second set of data supporting MMPs as effectors of the growth-promoting effects of semaphorins, and we identify the potential signalling pathway involved

Site-selective XAFS : a new tool for catalysis research

Site-selective X-ray absorption fine structure (XAFS) experiments will become an important tool in the study of active sites and metal-support interactions in catalysis. Site-selective XAFS is possible with the detection of specific X-ray emission channels. Selectivity can be obtained for the valence or for the nature of the neighbouring atoms. This opens a wide range of new experiments, for example with valence-selective XAFS the difference in local structure of an element present with two valences can be studied. With site-selective XAFS the local surroundings of a metal in contact with oxygen or carbon can be differentiated from the local surroundings of all the other metal atoms

Site-selective XAFS : a new tool for catalysis research

Site-selective X-ray absorption fine structure (XAFS) experiments will become an important tool in the study of active sites and metal-support interactions in catalysis. Site-selective XAFS is possible with the detection of specific X-ray emission channels. Selectivity can be obtained for the valence or for the nature of the neighbouring atoms. This opens a wide range of new experiments, for example with valence-selective XAFS the difference in local structure of an element present with two valences can be studied. With site-selective XAFS the local surroundings of a metal in contact with oxygen or carbon can be differentiated from the local surroundings of all the other metal atoms

Spectral sharpening of the Pt L edges by high-resolution x-ray emission

The platinum 2p(3/2), 2p(1/2), and 2s x-ray absorption spectra, recorded by monitoring the fluorescence intensity with eV energy resolution, show a spectral broadening that is significantly less than the 2p and 2s core hole lifetime broadening. The background of such spectral sharpening is discussed. It is shown, experimentally as well as theoretically, that the lifetime broadening of the 2p and 2s core holes is replaced by a new lifetime broadening. It is demonstrated that from the combination of normal x-ray absorption, selective x-ray absorption, and x-ray emission, the individual lifetimes of all participating core states can be determined. The difference between the 5d(5/2) and 5d(3/2) densities of states can be obtained from a combination of the 2p(1/2) and 2p(3/2) x-ray absorption spectra. The present spectra are limited by the experimental resolution. With the prospect of an improved experimental resolution for x-ray excitation and decay, the Pt edge absorption spectra could be obtained with even better resolution, thus providing a high-resolution hard x-ray probe of the empty density of states with important advantages for in-situ and high-pressure studies