660 research outputs found

    Modeling of RTS noise in MOSFETs under steady-state and large-signal excitation

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    The behavior of RTS noise in MOSFETs under large-signal excitation is experimentally studied. Our measurements show a significant transient effect, in line with earlier reports. We present a new physical model to describe this transient behavior and to predict RTS noise in MOSFETs under large-signal excitation. With only three model parameters the behavior is well described, contrary to existing models

    An Alternate Method for Fourier Transform Infrared (FTIR) Spectroscopic Determination of Soil Nitrate Using Derivative Analysis and Sample Treatments

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    This study aimed at examining effective sample treatments and spectral processing for an alternate method of soil nitrate determination using the attenuated total reflectance (ATR) of Fourier transform infrared (FTIR) spectroscopy. Prior to FTIR measurements, soil samples were prepared as paste to enhance adhesion between the ATR crystal and sample. The similar nitrate peak heights of soil pastes and their supernatants indicated that the nitrate in the liquid portion of the soil paste mainly responded to the FTIR signal. Using a 0.01-M CaSO4 solution for the soil paste, which has no interference bands in the characteristic spectra of the analyte, increased the concentration of the nitrates to be measured. Second-order derivatives were used in the prediction model to minimize the interference effects and enhance the performance. The second-order derivative spectra contained a unique nitrate peak in a range of 1,400-1,200 cm(-1) without interference of carbonate. A partial least square regression model using second-order derivative spectra performed well (R (2) = 0.995, root mean square error (RMSE) = 23.5, ratio of prediction to deviation (RPD) = 13.8) on laboratory samples. Prediction results were also good for a test set of agricultural field soils with a CaCO3 concentration of 6% to 8% (R (2) = 0.97, RMSE = 18.6, RPD = 3.5). Application of the prediction model based on soil paste samples to nitrate stock solution resulted in an increased RMSE (62.3); however, validation measures were still satisfactory (R (2) = 0.99, RPD = 3.0

    Modelling of industrial biopharmaceutical multicomponent chromatography

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    The development and validation of a chromatography rate model for an industrial multicomponent chromatographicbioseparation is presented. The model is intended for use in a process scenario to allow specific variables critical toproduct quality to be studied. The chromatography provides impurity clearance whilst producing a complex productcomposed of six closely related variants of a dimer protein therapeutic (∼30 kDa), with their monomer subunits in aspecific ratio. Impurity removal is well understood, however, achieving the correct monomer subunit ratio can posea purification challenge. We utilise a stepwise approach to develop a model for studying the effect of feed materialvariability on product quality. Scale down experiments are completed to quickly generate data for estimating modelparameters, before an iterative procedure is employed where the industrial process is used to refine parameters ina sequential manner, until model predictions exhibit satisfactory agreement with experimental data. Final modelpredictions were in good agreement with experimental product quality (within 3%). The results demonstrate howgood understanding of an industrial process can help facilitate model development when an exhaustive descrip-tion is not required, despite considering a chromatographic bioseparation with crude feed material and challengingpurification objectives

    Plasma charging damage reduction in IC processing by a self-balancing interconnect

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    A small TPC has been read out by means of a Medipix2 chip as direct anode. A Micromegas foil was placed Click to view the MathML source above the chip, and electron multiplication occurred in the gap. With a He/isobutane 80/20 mixture, gas multiplication factors up to tens of thousands were achieved, resulting in an efficiency for detecting single electrons of better than 90%. With this new readout technology for gas-filled detectors we recorded many image frames containing 2D images with tracks from cosmic muons. Along these tracks, electron clusters were observed, as well as ?-rays. With a gas layer thickness of only 1 mm, the device could be applied as vertex detector, outperforming all Si-based detectors

    Cross-site collaboration on infection prevention and control research—room for improvement? A 7-year comparative study in five European countries

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    Background: The spread of SARS-CoV-2, multidrug-resistant organisms and other healthcare-associated pathogens represents supra-regional challenges for infection prevention and control (IPC) specialists in every European country. To tackle these problems, cross-site research collaboration of IPC specialists is very important. This study assesses the extent and quality of national research collaborations of IPC departments of university hospitals located in Austria, England, France, Germany, and the Netherlands, identifies network gaps, and provides potential solutions. Methods: Joint publications of IPC heads of all university hospitals of the included countries between 1st of June 2013 until 31st of May 2020 were collected by Pubmed/Medline search. Further, two factors, the journal impact factor and the type/position of authorship, were used to calculate the Scientific Collaboration Impact (SCI) for all included sites; nationwide network analysis was performed. Results: In five European countries, 95 sites and 125 responsible leaders for IPC who had been in charge during the study period were identified. Some countries such as Austria have only limited national research cooperations, while the Netherlands has established a gapless network. Most effective collaborating university site of each country were Lille with an SCI of 1146, Rotterdam (408), Berlin (268), Sussex (204), and Vienna/Innsbruck (18). Discussion: The present study indicates major differences and room for improvement in IPC research collaborations within each country and underlines the potential and importance of collaborating in IPC.Projekt DEA

    Cross-site collaboration on infection prevention and control research—room for improvement? A 7-year comparative study in five European countries

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    Background: The spread of SARS-CoV-2, multidrug-resistant organisms and other healthcare-associated pathogens represents supra-regional challenges for infection prevention and control (IPC) specialists in every European country. To tackle these problems, cross-site research collaboration of IPC specialists is very important. This study assesses the extent and quality of national research collaborations of IPC departments of university hospitals located in Austria, England, France, Germany, and the Netherlands, identifies network gaps, and provides potential solutions. Methods: Joint publications of IPC heads of all university hospitals of the included countries between 1st of June 2013 until 31st of May 2020 were collected by Pubmed/Medline search. Further, two factors, the journal impact factor and the type/position of authorship, were used to calculate the Scientific Collaboration Impact (SCI) for all included sites; nationwide network analysis was performed. Results: In five European countries, 95 sites and 125 responsible leaders for IPC who had been in charge during the study period were identified. Some countries such as Austria have only limited national research cooperations, while the Netherlands has established a gapless network. Most effective collaborating university site of each country were Lille with an SCI of 1146, Rotterdam (408), Berlin (268), Sussex (204), and Vienna/Innsbruck (18). Discussion: The present study indicates major differences and room for improvement in IPC research collaborations within each country and underlines the potential and importance of collaborating in IPC

    TGF-β maintains dormancy of prostatic stem cells in the proximal region of ducts

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    We have previously shown that prostatic stem cells are located in the proximal region of mouse prostatic ducts. Here, we show that this region responds differently to transforming growth factor (TGF)-β than the distal ductal region and that under physiological conditions androgens and TGF-β are crucial overall regulators of prostatic tissue homeostasis. This conclusion is supported by the observations showing that high levels of TGF-β signaling are present in the quiescent proximal region of ducts in an androgen-replete animal and that cells in this region overexpress Bcl-2, which protects them from apoptosis. Moreover, androgen ablation reverses the proximal-distal TGF-β signaling gradient, leading to an increase in TGF-β signaling in the unprotected distal region (low Bcl-2 expression). This reversal of TGF-β–mediated signaling accompanies apoptosis of cells in the distal region and gland involution after androgen withdrawal. A physiological TGF-β signaling gradient (high proximally and low distally) and its functional correlates are restored after androgen replenishment. In addition to highlighting the regulatory role of androgens and TGF-β, these findings may have important implications for the deregulation of the stem cell compartment in the etiology of proliferative prostatic diseases

    Patterns of seasonal phytoplankton distribution in prairie saline lakes of the northern Great Plains (U.S.A.)

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    Seasonal changes in freshwater phytoplankton communities have been extensively studied, but key drivers of phytoplankton in saline lakes are currently not well understood. Comparative lake studies of 19 prairie saline lakes in the northern Great Plains (USA) were conducted in spring and summer of 2004, with data gathered for a suite of limnological parameters. Nutrient enrichment assays for natural phytoplankton assemblages were also performed in spring and summer of 2006. Canonical correspondence analysis of 2004 data showed salinity (logCl), nitrogen, and phosphorus (N:P ratios) to be the main drivers of phytoplankton distribution in the spring, and phosphorus (C:P ratios), iron (logTFe), and nitrogen (logTN) as important factors in the summer. Despite major differences in nutrient limitation patterns (P-limitation in freshwater systems, N-limitation in saline systems), seasonal patterns of phytoplankton phyla changes in these saline lakes were similar to those of freshwater systems. Dominance shifted from diatoms in the spring to cyanobacteria in the summer. Nutrient enrichment assays (control, +Fe, +N, +P, +N+P) in 2006 indicated that nutrient limitation is generally more consistent within lakes than for individual taxa across systems, with widespread nitrogen and secondary phosphorus limitation. Understanding phytoplankton community structure provides insight into the overall ecology of saline lakes, and will assist in the future conservation and management of these valuable and climatically-sensitive systems

    Nanotextured Superhydrophobic Electrodes Enable Detection of Attomolar-Scale DNA Concentration within a Droplet by Non-Faradaic Impedance Spectroscopy

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    Label-free, rapid detection of biomolecules in microliter volumes of highly diluted solutions (subfemtomolar) is of essential importance for numerous applications in medical diagnostics, food safety, and chem-bio sensing for homeland security. At ultra-low concentrations, regardless of the sensitivity of the detection approach, the sensor response time is limited by physical diffusion of molecules towards the sensor surface.We have developed a fast, low cost, non-faradaic impedance sensing method for detection of synthetic DNA molecules in DI water at attomolar levels by beating the diffusion limit through evaporation of a micro-liter droplet of DNA on a nanotextured superhydrophobic electrode array. Continuous monitoring of the impedance of individual droplets as a function of evaporation time is exploited to dramatically improve the sensitivity and robustness of detection. Formation of the nanostructures on the electrode surface not only increases the surface hydrophobicity, but also allows robust pinning of the droplet contact area to the sensor surface. These two features are critical for performing highly stable impedance measurements as the droplet evaporates. Using this scheme, the detection limit of conventional non-faradaic methods is improved by five orders of magnitude. The proposed platform represents a step-forward towards realization of ultra-sensitive lab-on-chip biomolecule detectors for real time point-of-care application. Further works are however needed to ultimately realize the full potential of the proposed approach to appraise biological samples in complex buffer solutions rather than in DI water
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