382 research outputs found

    Homogeneous bubble nucleation limit of mercury under the normal working conditions of the planned European Spallation Source

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    In spallation neutron sources, liquid mercury is the subject of big thermal and pressure shocks, upon adsorbing the proton beam. These changes can cause unstable bubbles in the liquid, which can damage the structural material. While there are methods to deal with the pressure shock, the local temperature shock cannot be avoided. In our paper we calculated the work of the critical cluster formation (i.e. for mercury micro-bubbles) together with the rate of their formation (nucleation rate). It is shown that the homogeneous nucleation rates are very low even after adsorbing several proton pulses, therefore the probability of temperature induced homogeneous bubble nucleation is negligible.Comment: 22 Pages, 11 figures, one of them is colour, we plan to publish it in Eur. Phys. J.

    Surgical treatment for pulmonary metastases from esophageal carcinoma after definitive chemoradiotherapy: Experience from a single institution

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    <p>Abstract</p> <p>Background</p> <p>Surgical treatment for pulmonary metastases is known to be a safe and potentially curative procedure for various primary malignancies. However, there are few reports regarding the prognostic role of surgical treatment for pulmonary metastases from esophageal carcinoma, especially after definitive chemoradiotherapy (CRT).</p> <p>Methods</p> <p>We retrospectively reviewed 5 patients who underwent surgical treatment for pulmonary metastases from esophageal carcinoma at our institution. The primary treatment for esophageal carcinoma was definitive CRT, and a complete response (CR) was achieved in all patients.</p> <p>Results</p> <p>The surgical procedure for pulmonary metastases was wedge resection, and pathological complete resection was achieved in all 5 patients. The disease free interval after definitive CRT varied from 7 to 36 months, with a median of 19 months. There were no perioperative complications, but postoperative respiratory failure occurred in 1 patient. The postoperative hospital stay varied from 4 to 7 days, with a median of 6 days. Three patients are now alive with a good performance status (PS) and are disease free. The other 2 patients died of primary disease. The overall survival after surgical treatment varied from 20 to 90 months, with a median of 29 months.</p> <p>Conclusions</p> <p>Surgical treatment should be considered for patients with pulmonary metastases from esophageal carcinoma who previously received CRT and achieved a CR, because it provides not only a longer survival, but also a good postoperative PS for some patients.</p

    Regulation of Epithelial Cell Morphology and Functions Approaching To More In Vivo-Like by Modifying Polyethylene Glycol on Polysulfone Membranes

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    Cytocompatibility is critically important in design of biomaterials for application in tissue engineering. However, the currently well-accepted β€œcytocompatible" biomaterials are those which promote cells to sustain good attachment/spreading. The cells on such materials usually lack the self-assembled cell morphology and high cell functions as in vivo. In our view, biomaterials that can promote the ability of cells to self-assemble and demonstrate cell-specific functions would be cytocompatible. This paper examined the interaction of polyethylene glycol (PEG) modified polysulfone (PSf) membranes with four epithelial cell types (primary liver cells, a liver tumor cell line, and two renal tubular cell lines). Our results show that PSf membranes modified with proper PEG promoted the aggregation of both liver and renal cells, but the liver cells more easily formed aggregates than the renal tubular cells. The culture on PEG-modified PSf membranes also enhanced cell-specific functions. In particular, the cells cultured on F127 membranes with the proper PEG content mimicked the in vivo ultrastructure of liver cells or renal tubules cells and displayed the highest cell functions. Gene expression data for adhesion proteins suggest that the PEG modification impaired cell-membrane interactions and increased cell-cell interactions, thus facilitating cell self-assembly. In conclusion, PEG-modified membrane could be a cytocompatible material which regulates the morphology and functions of epithelial cells in mimicking cell performance in vivo

    A Quaternary ZnCdSeTe Nanotip Photodetector

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    The authors report the growth of needle-like high density quaternary Zn0.87Cd0.13Se0.98Te0.02nanotips on oxidized Si(100) substrate. It was found that average length and average diameter of the nanotips were 1.3 ΞΌm and 91 nm, respectively. It was also found that the as-grown ZnCdSeTe nanotips exhibit mixture of cubic zinc-blende and hexagonal wurtzite structures. Furthermore, it was found that the operation speeds of the fabricated ZnCdSeTe nanotip photodetector were fast with turn-on and turn-off time constants both less than 2 s

    Modeling allosteric signal propagation using protein structure networks

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    Allosteric communication in proteins can be induced by the binding of effective ligands, mutations or covalent modifications that regulate a site distant from the perturbed region. To understand allosteric regulation, it is important to identify the remote sites that are affected by the perturbation-induced signals and how these allosteric perturbations are transmitted within the protein structure. In this study, by constructing a protein structure network and modeling signal transmission with a Markov random walk, we developed a method to estimate the signal propagation and the resulting effects. In our model, the global perturbation effects from a particular signal initiation site were estimated by calculating the expected visiting time (EVT), which describes the signal-induced effects caused by signal transmission through all possible routes. We hypothesized that the residues with high EVT values play important roles in allosteric signaling. We applied our model to two protein structures as examples, and verified the validity of our model using various types of experimental data. We also found that the hot spots in protein binding interfaces have significantly high EVT values, which suggests that they play roles in mediating signal communication between protein domains

    hnRNP I Inhibits Notch Signaling and Regulates Intestinal Epithelial Homeostasis in the Zebrafish

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    Regulated intestinal stem cell proliferation and differentiation are required for normal intestinal homeostasis and repair after injury. The Notch signaling pathway plays fundamental roles in the intestinal epithelium. Despite the fact that Notch signaling maintains intestinal stem cells in a proliferative state and promotes absorptive cell differentiation in most species, it remains largely unclear how Notch signaling itself is precisely controlled during intestinal homeostasis. We characterized the intestinal phenotypes of brom bones, a zebrafish mutant carrying a nonsense mutation in hnRNP I. We found that the brom bones mutant displays a number of intestinal defects, including compromised secretory goblet cell differentiation, hyperproliferation, and enhanced apoptosis. These phenotypes are accompanied by a markedly elevated Notch signaling activity in the intestinal epithelium. When overexpressed, hnRNP I destabilizes the Notch intracellular domain (NICD) and inhibits Notch signaling. This activity of hnRNP I is conserved from zebrafish to human. In addition, our biochemistry experiments demonstrate that the effect of hnRNP I on NICD turnover requires the C-terminal portion of the RAM domain of NICD. Our results demonstrate that hnRNP I is an evolutionarily conserved Notch inhibitor and plays an essential role in intestinal homeostasis
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