118 research outputs found
An all-ZnO microbolometer for infrared imaging
Cataloged from PDF version of article.Microbolometers are extensively used for uncooled infrared imaging applications. These imaging units generally employ vanadium oxide or amorphous silicon as the active layer and silicon nitride as the absorber layer. However, using different materials for active and absorber layers increases the fabrication and integration complexity of the pixel structure. In order to reduce fabrication steps and therefore increase the yield and reduce the cost of the imaging arrays, a single layer can be employed both as the absorber and the active material. In this paper, we propose an all-ZnO microbolometer, where atomic layer deposition grown zinc oxide is employed both as the absorber and the active material. Optical constants of ZnO are measured and fed into finite-difference-time-domain simulations where absorption performances of microbolometers with different gap size and ZnO film thicknesses are extracted. Using the results of these optical simulations, thermal simulations are conducted using finite-element-method in order to extract the noise equivalent temperature difference (NETD) and thermal time constant values of several bolometer structures with different gap sizes, arm and film thicknesses. It is shown that the maximum performance of 171 mK can be achieved with a body thickness of 1.1 ΞΌm and arm thickness of 50 nm, while the fastest response with a time constant of 0.32 ms can be achieved with a ZnO thickness of 150 nm both in arms and body. Β© 2014 Elsevier B.V. All rights reserved
The metabolic syndrome is not associated with homocysteinemia: The Persian Gulf Healthy Heart Study
Background: It is uncertain whether homocysteine
and the metabolic syndrome or its components are related
in the general population, as studies investigating the
association between homocysteine levels and insulin resistance
have shown conflicting results. Methods: In an ancillary
study to the Persian Gulf Healthy Heart Study, a cohort
study of Iranian men and women aged β₯25 yr, a random sample
of 1754 subjects were evaluated for the association of
plasma homocysteine levels and the metabolic syndrome using
National Cholesterol Education Program (NCEP)-Adult
Treatment Panel (ATP)-III criteria. Total homocysteine levels
and high sensitivity C-reactive protein (CRP) were determined
by enzyme-linked immunosorbent assays. Results: Subjects
with lower HDL-cholesterol and higher blood pressure
showed significantly higher homocysteine levels (p=0.001
and p<0.0001; respectively). There was no significant difference
in serum levels of homocysteine between subjects with
and without the metabolic syndrome. In multiple logistic regression
analysis, the metabolic syndrome did not show a
significant association with serum homocysteine levels after
adjusting for sex, age, smoking, fruit and vegetable intake
pattern, body mass index, and physical inactivity. Concurrent
elevated CRP levels and the metabolic syndrome also did not
show a significant association with serum homocysteine levels
after adjusting for sex, age, and lifestyle cardiovascular
risk factors. Conclusions: There was no association between
the metabolic syndrome using NCEP-ATPIII criteria and homocysteinemia
in this study. These data refute the hypothesis
that homocysteine levels are influenced by the metabolic
syndrome, at least in general healthy population
DOGS: Reaction-Driven de novo Design of Bioactive Compounds
We present a computational method for the reaction-based de novo design of drug-like molecules. The software DOGS (Design of Genuine Structures) features a ligand-based strategy for automated βin silicoβ assembly of potentially novel bioactive compounds. The quality of the designed compounds is assessed by a graph kernel method measuring their similarity to known bioactive reference ligands in terms of structural and pharmacophoric features. We implemented a deterministic compound construction procedure that explicitly considers compound synthesizability, based on a compilation of 25'144 readily available synthetic building blocks and 58 established reaction principles. This enables the software to suggest a synthesis route for each designed compound. Two prospective case studies are presented together with details on the algorithm and its implementation. De novo designed ligand candidates for the human histamine H4 receptor and Ξ³-secretase were synthesized as suggested by the software. The computational approach proved to be suitable for scaffold-hopping from known ligands to novel chemotypes, and for generating bioactive molecules with drug-like properties
Inhibitors of Helicobacter pylori Protease HtrA Found by βVirtual Ligandβ Screening Combat Bacterial Invasion of Epithelia
Background: The human pathogen Helicobacter pylori (H. pylori) is a main cause for gastric inflammation and cancer. Increasing bacterial resistance against antibiotics demands for innovative strategies for therapeutic intervention. Methodology/Principal Findings: We present a method for structure-based virtual screening that is based on the comprehensive prediction of ligand binding sites on a protein model and automated construction of a ligand-receptor interaction map. Pharmacophoric features of the map are clustered and transformed in a correlation vector (βvirtual ligandβ) for rapid virtual screening of compound databases. This computer-based technique was validated for 18 different targets of pharmaceutical interest in a retrospective screening experiment. Prospective screening for inhibitory agents was performed for the protease HtrA from the human pathogen H. pylori using a homology model of the target protein. Among 22 tested compounds six block E-cadherin cleavage by HtrA in vitro and result in reduced scattering and wound healing of gastric epithelial cells, thereby preventing bacterial infiltration of the epithelium. Conclusions/Significance: This study demonstrates that receptor-based virtual screening with a permissive (βfuzzyβ) pharmacophore model can help identify small bioactive agents for combating bacterial infection
Drug Discovery Using Chemical Systems Biology: Identification of the Protein-Ligand Binding Network To Explain the Side Effects of CETP Inhibitors
Systematic identification of protein-drug interaction networks is crucial to correlate complex modes of drug action to clinical indications. We introduce a novel computational strategy to identify protein-ligand binding profiles on a genome-wide scale and apply it to elucidating the molecular mechanisms associated with the adverse drug effects of Cholesteryl Ester Transfer Protein (CETP) inhibitors. CETP inhibitors are a new class of preventive therapies for the treatment of cardiovascular disease. However, clinical studies indicated that one CETP inhibitor, Torcetrapib, has deadly off-target effects as a result of hypertension, and hence it has been withdrawn from phase III clinical trials. We have identified a panel of off-targets for Torcetrapib and other CETP inhibitors from the human structural genome and map those targets to biological pathways via the literature. The predicted protein-ligand network is consistent with experimental results from multiple sources and reveals that the side-effect of CETP inhibitors is modulated through the combinatorial control of multiple interconnected pathways. Given that combinatorial control is a common phenomenon observed in many biological processes, our findings suggest that adverse drug effects might be minimized by fine-tuning multiple off-target interactions using single or multiple therapies. This work extends the scope of chemogenomics approaches and exemplifies the role that systems biology has in the future of drug discovery
Light regulation of metabolic pathways in fungi
Light represents a major carrier of information in nature. The molecular machineries translating its electromagnetic energy (photons) into the chemical language of cells transmit vital signals for adjustment of virtually every living organism to its habitat. Fungi react to illumination in various ways, and we found that they initiate considerable adaptations in their metabolic pathways upon growth in light or after perception of a light pulse. Alterations in response to light have predominantly been observed in carotenoid metabolism, polysaccharide and carbohydrate metabolism, fatty acid metabolism, nucleotide and nucleoside metabolism, and in regulation of production of secondary metabolites. Transcription of genes is initiated within minutes, abundance and activity of metabolic enzymes are adjusted, and subsequently, levels of metabolites are altered to cope with the harmful effects of light or to prepare for reproduction, which is dependent on light in many cases. This review aims to give an overview on metabolic pathways impacted by light and to illustrate the physiological significance of light for fungi. We provide a basis for assessment whether a given metabolic pathway might be subject to regulation by light and how these properties can be exploited for improvement of biotechnological processes
Idiopathic weight loss due to an entero-enteric fistula from a gossypiboma retained for 27 years
Gossypiboma refers to a mass formed around surgical instruments or materials left in the body postoperatively. The occurrence of gossypibomas remains an important problem, despite improvements in surgical procedures and operating room facilities. The clinical presentation of gossypiboma can vary depending on the host response. This report describes a case of abdominal gossypiboma after splenectomy. A 48-year-old man who had undergone splenectomy 27 years ago was admitted to our clinic suffering from non-specific symptoms for 2 weeks. He was cachectic, but laboratory test results were normal. Abdominal ultrasonography and computed tomography revealed a mass in the left hypochondrium. An entero-enteric fistula and an encapsulated foreign body (surgical compress) were detected during an exploratory laparotomy, and the foreign body was removed. Preventing gossypibomas is very important because of their potential to create medico-legal problems and increase mortality and morbidity. Therefore, forgotten surgical material should be considered in all patients with a surgical history, and surgery should be performed carefully. Β© 2018 Turkish Surgical Association
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