Multilayer Polarizer at the Energy of 50–1000 eV

Accurate evaluation of polarization states of the radiation is necessary for polarization-sensitive studies, which requires polarization optical elements, such as polarizer, analyzer, and phase retarder. In extreme ultraviolet (EUV) and soft X-ray region, the closeness of the real part of the refractive index to unity, coupled with high absorption, makes the realization of polarizers such as birefringence and dichroic polarizers impossible. Periodical multilayers are commonly used in polarization study working at the quasi-Brewster angle. To expand narrow spectral bandwidths of periodic multilayers, aperiodic and lateral gradual multilayer polarizers including reflective analyzers and transmission phase retarders are utilized. In this chapter, we demonstrate a series of periodic, aperiodic, and lateral gradual broadband multilayer polarizers with the material combinations of Mo/Si, Mo/Y, Mo/B4C, Cr/C, Cr/Sc, Cr/Ti, Cr/V, WSi2/Si, W/B4C, etc. Different multilayer polarizers correspond to different energy ranges, covering 50–1000 eV totally, including “water window” and the L absorption edges of Fe, Co, and Ni. Polarization measurements are performed at BESSY II, Diamond Light Source, National Synchrotron Radiation Laboratory in Hefei and Beijing Synchrotron Radiation Facility. Some of the polarizers we have developed are applied to the polarization measurements of BESSY II UE56/1-PGM and Beamline 3W1B of Beijing Synchrotron Radiation Facility

Electronic structure and hybridization of CaS by means of X-ray absorption spectroscopy at Ca and S K-edges.

The cubic calcium sulfide (CaS) is a well known system and an attractive building block material for many luminescence technological applications. However, it is essential to achieve an accurate understanding of its electronic structure in order to engineer its band structure for optimized applications. Here a study of the electronic structure of CaS by means of X-ray absorption spectroscopy performed at both Ca and SK-edges, and calculations performed in the framework of the multiple-scattering theory and of the finite difference method are presented. At the CaK-edge the presence of an anomalousdstates feature is discussed while in the SK-edge spectrum the presence of a pre-edge shoulder owing to the hybridization among Cadstates and Spstates is pointed out. Although thel-projected density of states of CaS is in good agreement with previous first-principles calculations, the standard muffin-tin potential is inadequate to reproduce near-edge structures at both Ca and SK-edges in this system. Indeed, with its highly symmetric and less compact structure, CaS is characterized by a large set of collinear atomic configurations that pose severe constraints on the construction of the atomic potential. On the contrary, the finite-difference method with no muffin-tin approximation is more suitable for X-ray absorption calculations in this system

Cr/C Reflective Multilayer for Wavelength of 44.8 Å

International audienceThe working wavelength of Ni-like, Ta soft X-ray laser is 44.8 Å, just near the "water window." High reflection multilayers are required for this kind of laser in China. In this work, we design and fabricate carbon-based multilayer reflective samples. The Cr/C multilayer was selected from proposed candidates such as Co/C, Ni/C, and CoCr/C material combinations. The period thickness is only 22.6 Å. Cr/C multilayers were deposited by the magnetron sputtering method. Multilayers with bi-layer numbers of 150, 200, 250 and 300 were deposited onto super polished silicon wafers. All multilayers have been characterized by grazing incidence X-ray reflectance (GIXRR). Then, near-normal incidence reflectance measurements were performed at beamline 3W1B, Beijing synchrotron radiation (BSRF). The highest reflectance of 13.2% is achieved with the bi-layer number of 300. Transmission electron microscopy measurements also clearly show the sharp Cr-C interfaces in the multilayer

LPA induces IL-6 secretion from aortic smooth muscle cells via an LPA1-regulated, PKC-dependent, and p38α-mediated pathway

Lysophosphatidic acid (LPA) is a potent bioactive lysophospholipid. Accumulated evidence supports a role for LPA in inflammation. To profile LPA-induced cytokine production in vascular smooth muscle cells (SMCs), we used a cytokine antibody array system and found that LPA prominently induces the secretion of IL-6 and monocyte chemoattractant protein (MCP)-1 from human aortic SMCs (HASMCs). The mechanism by which LPA induces MCP-1 expression in SMCs has been previously reported. However, LPA induction of IL-6 secretion from vascular SMCs and its regulatory mechanism are unknown. The present study reveals that LPA induces the expression of IL-6 mRNA and protein in HASMCs as well as the secretion of IL-6 protein in a time-dependent manner. Our results demonstrate that LPA-specific receptor 1 (LPA1) mediates LPA-induced IL-6 secretion and that LPA induction of IL-6 is independent of the EGF receptor pathway. Our data further show that PKC-mediated p38 MAPK is responsible for the IL-6 secretion. Finally, small interfering RNA depletion experiments revealed that p38α is specifically responsible for the LPA-induced IL-6 secretion. The present study profiles the regulatory relationship between LPA and multiple cytokines in vascular SMCs for the first time, provides the first evidence that LPA upregulates IL-6 in vascular SMCs, and reveals the regulatory mechanism of LPA-induced IL-6 production in HASMCs. In light of the emerging roles of LPA and IL-6 in vascular inflammation, the understanding of the regulatory mechanism may contribute to the treatment and prevention of cardiovascular disorders

X-ray reflectivity and scanning-tunneling-microscopy study of surface roughness scaling of molybdenum films

An X-ray reflectivity (XR) study of the dynamic evolution of the film surface was carried out for molybdenum (Mo) sputter-deposited onto silicon substrates. The Mo-air interface width grows with time, and exhibits a power law behavior. The growth exponent β is found to be 0.42. The time-invariant self-affine behavior on the short-range scale has also been observed, and is consistent with the dynamic scaling theory. The roughness exponent α is found to be $0.89\pm 0.05$. Scanning tunneling microscopy (STM) was also used to characterize the surface and showed good agreement with the XR measurements

Structural and component characterization of the B4C neutron conversion layer deposited by magnetron sputtering

Neutron conversion detectors that use 10B-enriched boron carbide are feasible alternatives to 3He-based detectors. We prepared boron carbide films at micron-scale thickness using direct-current magnetron sputtering. The structural characteristics of natural B4C films, including density, roughness, crystallization, and purity, were analyzed using grazing incidence X-ray reflectivity, X-ray diffraction, X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and scanning electron microscopy. A beam profile test was conducted to verify the practicality of the 10B-enriched B4C neutron conversion layer. A clear profile indicated the high quality of the neutron conversion of the boron carbide layer

Histamine Induces Egr-1 Expression in Human Aortic Endothelial Cells via the H1 Receptor-mediated Protein Kinase Cδ-dependent ERK Activation Pathway*

Histamine, a potent inflammatory mediator, has multiple effects on the pathogenesis of atherosclerosis. This study investigates the effect of histamine on the expression of early growth response factor 1 (Egr-1), a master transcription factor that regulates the expression of an array of atherogenic genes in atherosclerotic lesions. Histamine markedly and rapidly induces Egr-1 mRNA and protein expression in primary human aortic endothelial cells (HAECs). Histamine-induced Egr-1 expression is dependent on the activation of the H1 receptor. Histamine also rapidly and transiently activates protein kinase C-δ (PKCδ), extracellular signal-regulated kinase (ERK)1/2, p38 kinase, and c-Jun N-terminal kinase (JNK) prior to Egr-1 induction. Using specific pharmacological inhibitors and small interfering RNA technology, we determined that PKCδ and ERK, but not p38 and JNK, mediate histamine-induced Egr-1 expression. Our data provide the first evidence that histamine regulates expression of Egr-1 in mammalian cells and demonstrate a novel role of PKCδ in up-regulation of Egr-1 expression. The present study reveals the following regulatory mechanism: histamine up-regulates Egr-1 expression in primary HAECs via the H1 receptor and the PKCδ-dependent ERK activation pathway. Our data also imply that CREB, a downstream component of the ERK pathway, regulates Egr-1 expression in HAECs. Importantly, these results suggest a central role of Egr-1 in histamine-induced gene expression and in histamine-induced vascular disease