203 research outputs found

    Development and modeling of a low temperature thin-film CMOS on glass

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    The push to develop integrated systems using thin-film transistors (TFT) on insulating substrates (i.e. glass) has always been limited due to low-mobility semiconducting films such as amorphous and polycrystalline silicon. Corning Incorporated is developing a new substrate material known as silicon-on-glass (SiOG). It is intrinsically better than amorphous and polycrystalline silicon materials due to its single crystal nature of the silicon film. This however does not mitigate the challenges associated with low temperature CMOS process and fabrication. The first generation of TFTs fabricated at RIT showed the potential of SiOG as a viable substrate material, but were plagued by considerable short comings such as high leakage and low transconductance. As part of this study, refinements to TFT processing on SiOG have demonstrated significant improvement to TFT performance and uniformity, showing increase transconductanace/mobility, lower subthreshold swing, tighter VT distributions, and near symmetrical NFET and PFET operation about 0 V. With these improvements minimal steps have been added to the manufacturing process, keeping simple and adoptable by the flat panel display (FPD) industry. Device modeling clearly demonstrates the key areas important to electrical operation, such as dopant activation, interface charge/trap reduction, and workfunction engineering. It addition, modeling and simulation have helped to explain the governing physics of device operation explaining non-ideal effects such as gate induced drain leakage (GIDL) and various mobility degradation mechanism. An overview of device design, process refinements and device operation is presented. Process modifications and resulting benefits are discussed along with CMOS integration on SiOG

    Specific inhibition of binding of antistasin and [A103,106,108] antistasin 93–119 to sulfatide (Gal(3-SO4)β1-1Cer) by glycosaminoglycans

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    AbstractLeech-derived antistasin is a potent anticoagulant and antimetastatic protein that binds sulfatide (Gal(3-SO4)β1-1Cer)and sulfated polysaccharides. In this study, the synthetic fragment [A103,106,108] antistasin 93–119, which corresponds to the carboxyl terminus, showed specific and saturable binding to sulfatide. Binding was competitively blocked by glycosaminoglycans (GAGs) in the order: dextran sulfate 5000 ≅ dextran sulfate 500 0OO > heparin > dermatan sulfate ⪢ chondroitin sulfates A and C. This rank order of inhibitory potency was identical to that observed with whole antistasin. We suggest that residues 93–119 of antistasin represent a critical domain for binding GAGs and sulfated glycolipids

    Optimising intraperitoneal gentamicin dosing in peritoneal dialysis patients with peritonitis (GIPD) study

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    Background: Antibiotics are preferentially delivered via the peritoneal route to treat peritonitis, a major complication of peritoneal dialysis (PD), so that maximal concentrations are delivered at the site of infection. However, drugs administered intraperitoneally can be absorbed into the systemic circulation. Drugs excreted by the kidneys accumulate in PD patients, increasing the risk of toxicity. The aim of this study is to examine a model of gentamicin pharmacokinetics and to develop an intraperitoneal drug dosing regime that maximises bacterial killing and minimises toxicity

    Cluster K Mycobacteriophages: Insights into the Evolutionary Origins of Mycobacteriophage TM4

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    Five newly isolated mycobacteriophages –Angelica, CrimD, Adephagia, Anaya, and Pixie – have similar genomic architectures to mycobacteriophage TM4, a previously characterized phage that is widely used in mycobacterial genetics. The nucleotide sequence similarities warrant grouping these into Cluster K, with subdivision into three subclusters: K1, K2, and K3. Although the overall genome architectures of these phages are similar, TM4 appears to have lost at least two segments of its genome, a central region containing the integration apparatus, and a segment at the right end. This suggests that TM4 is a recent derivative of a temperate parent, resolving a long-standing conundrum about its biology, in that it was reportedly recovered from a lysogenic strain of Mycobacterium avium, but it is not capable of forming lysogens in any mycobacterial host. Like TM4, all of the Cluster K phages infect both fast- and slow-growing mycobacteria, and all of them – with the exception of TM4 – form stable lysogens in both Mycobacterium smegmatis and Mycobacterium tuberculosis; immunity assays show that all five of these phages share the same immune specificity. TM4 infects these lysogens suggesting that it was either derived from a heteroimmune temperate parent or that it has acquired a virulent phenotype. We have also characterized a widely-used conditionally replicating derivative of TM4 and identified mutations conferring the temperature-sensitive phenotype. All of the Cluster K phages contain a series of well conserved 13 bp repeats associated with the translation initiation sites of a subset of the genes; approximately one half of these contain an additional sequence feature composed of imperfectly conserved 17 bp inverted repeats separated by a variable spacer. The K1 phages integrate into the host tmRNA and the Cluster K phages represent potential new tools for the genetics of M. tuberculosis and related species

    Acute-Phase-HDL Remodeling by Heparan Sulfate Generates a Novel Lipoprotein with Exceptional Cholesterol Efflux Activity from Macrophages

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    During episodes of acute-inflammation high-density lipoproteins (HDL), the carrier of so-called good cholesterol, experiences a major change in apolipoprotein composition and becomes acute-phase HDL (AP-HDL). This altered, but physiologically important, HDL has an increased binding affinity for macrophages that is dependent on cell surface heparan sulfate (HS). While exploring the properties of AP-HDL∶HS interactions we discovered that HS caused significant remodeling of AP-HDL. The physical nature of this change in structure and its potential importance for cholesterol efflux from cholesterol-loaded macrophages was therefore investigated. In the presence of heparin, or HS, AP-HDL solutions at pH 5.2 became turbid within minutes. Analysis by centrifugation and gel electrophoresis indicated that AP-HDL was remodeled generating novel lipid poor particles composed only of apolipoprotein AI, which we designate β2. This remodeling is dependent on pH, glycosaminoglycan type, is promoted by Ca2+ and is independent of protease or lipase activity. Compared to HDL and AP-HDL, remodeled AP-HDL (S-HDL-SAA), containing β2 particles, demonstrated a 3-fold greater cholesterol efflux activity from cholesterol-loaded macrophage. Because the identified conditions causing this change in AP-HDL structure and function can exist physiologically at the surface of the macrophage, or in its endosomes, we postulate that AP-HDL contains latent functionalities that become apparent and active when it associates with macrophage cell surface/endosomal HS. In this way initial steps in the reverse cholesterol transport pathway are focused at sites of injury to mobilize cholesterol from macrophages that are actively participating in the phagocytosis of damaged membranes rich in cholesterol. The mechanism may also be of relevance to aspects of atherogenesis
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