402 research outputs found

    Vertical thermal structure of the Venus atmosphere from temperature and pressure measurements

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    Accurate temperature and pressure measurements were made on the Vega-2 lander during its entire descent. The temperature and pressure at the surface were 733 K and 89.3 bar, respectively. A strong temperature inversion was found in the upper troposphere. Several layers with differing static stability were visible in the atmospheric structure

    Rapid and inexpensive purification of adenovirus vectors using an optimised aqueous two-phase technology.

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    Adenoviruses (AdVs) are used as gene therapy vectors to treat human diseases and as vaccines against COVID-19. AdVs are produced by transfecting human embryonic kidney 239 (HEK293) or PER.C6 virus producer cells with AdV plasmid vectors or infecting these cells withcell lysates containing replication-defective AdV. Cell lysates can be purified further by caesium chloride or chromatographic protocols to research virus seed stocks (RVSS) for characterisation to high quality master virus seed stocks (MVSS) and working virus seed stocks (WVSS) before downstream production of pure, high titre AdV. Lysates are poorly infectious, block filtration columns and have limited storage capability. Aqueous two-phase systems (ATPS) are an alternative method for AdV purification that rapidly generates cleaner RVSS for characterisation to MVSS. After testing multiple ATPS formulations, an aqueous mixture of 20 % PEG 600 and 20 % (NH4)2SO4 (w/w) was found most effective for AdV partitioning, producing up to 97+3% yield of high-titre virus that was devoid of aggregates both effective in vitro and in vivo with no observable cytotoxicity. Importantly, AdV preparations stored at −20 °C or 4 °C show negligible loss of titre and are suitable for downstream processing to clinical grade to support the need for AdV vaccines

    Separation of Oligosaccharides from Lotus Seeds via Medium-pressure Liquid Chromatography Coupled with ELSD and DAD

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    peer-reviewedLotus seeds were identified by the Ministry of Public Health of China as both food and medicine. One general function of lotus seeds is to improve intestinal health. However, to date, studies evaluating the relationship between bioactive compounds in lotus seeds and the physiological activity of the intestine are limited. In the present study, by using medium pressure liquid chromatography coupled with evaporative light-scattering detector and diode-array detector, five oligosaccharides were isolated and their structures were further characterized by electrospray ionization-mass spectrometry and gas chromatography-mass spectrometry. In vitro testing determined that LOS3-1 and LOS4 elicited relatively good proliferative effects on Lactobacillus delbrueckii subsp. bulgaricus. These results indicated a structure-function relationship between the physiological activity of oligosaccharides in lotus seeds and the number of probiotics applied, thus providing room for improvement of this particular feature. Intestinal probiotics may potentially become a new effective drug target for the regulation of immunity

    Rapid and inexpensive purification of adenovirus vectors using an optimised aqueous two-phase technology

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    Copyright © 2021 The Author(s). Adenoviruses (AdVs) are used as gene therapy vectors to treat human diseases and as vaccines against COVID-19. AdVs are produced by transfecting human embryonic kidney 239 (HEK293) or PER.C6 virus producer cells with AdV plasmid vectors or infecting these cells withcell lysates containing replication-defective AdV. Cell lysates can be purified further by caesium chloride or chromatographic protocols to research virus seed stocks (RVSS) for characterisation to high quality master virus seed stocks (MVSS) and working virus seed stocks (WVSS) before downstream production of pure, high titre AdV. Lysates are poorly infectious, block filtration columns and have limited storage capability. Aqueous two-phase systems (ATPS) are an alternative method for AdV purification that rapidly generates cleaner RVSS for characterisation to MVSS. After testing multiple ATPS formulations, an aqueous mixture of 20 % PEG 600 and 20 % (NH4)2SO4 (w/w) was found most effective for AdV partitioning, producing up to 97+3% yield of high-titre virus that was devoid of aggregates both effective in vitro and in vivo with no observable cytotoxicity. Importantly, AdV preparations stored at −20 °C or 4 °C show negligible loss of titre and are suitable for downstream processing to clinical grade to support the need for AdV vaccines.Brunel University London Brief award

    Thermal structure in the Venus middle cloud layer

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    Thermal structure measurements obtained by the two Vega balloons show the Venus atmosphere in the middle cloud layer to be near-adiabatic, on the whole; but discrete air masses are present that differ slightly from one another in potential temperature and entropy. The Vega 1 temperatures are 6.5 K warmer than measured by Vega 2 at given pressures. Measurements taken by the Vega 2 lander on descent through these levels agree with the Vega 2 balloon data

    1 &#956;m gate length, In<sub>0.75</sub>Ga<sub>0.25</sub>As channel, thin body n-MOSFET on InP substrate with transconductance of 737&#956;S/&#956;m

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    The first demonstration of implant-free, flatband-mode In&lt;sub&gt;0.75&lt;/sub&gt;Ga&lt;sub&gt;0.25&lt;/sub&gt;As channel n-MOSFETs is reported. These 1 &#956;m gate length MOSFETs, fabricated on a structure with average mobility of 7720 cm&lt;sup&gt;2&lt;/sup&gt;/Vs and sheet carrier concentration of 3.3&#215;10&lt;sup&gt;12&lt;/sup&gt; cm&lt;sup&gt;-22&lt;/sup&gt;, utilise a Pt gate, a high-k dielectric (k&#8776;20), and a &#948;-doped InAlAs/InGaAs/InAlAs heterostructure. The devices have a typical maximum drive current (I&lt;sub&gt;d,sat&lt;/sub&gt;) of 933 &#956;A/&#956;m, extrinsic transconductance (g&lt;sub&gt;m&lt;/sub&gt;) of 737 &#956;S/&#956;m, gate leakage (I&lt;sub&gt;g&lt;/sub&gt;) of 40 pA, and on-resistance (R&lt;sub&gt;on&lt;/sub&gt;) of 555 &#937;&#956;m. The g&lt;sub&gt;m&lt;/sub&gt; and R&lt;sub&gt;on&lt;/sub&gt; figures of merit are the best reported to date for any III-V MOSFET

    The Inviscid Limit and Boundary Layers for Navier-Stokes Flows

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    The validity of the vanishing viscosity limit, that is, whether solutions of the Navier-Stokes equations modeling viscous incompressible flows converge to solutions of the Euler equations modeling inviscid incompressible flows as viscosity approaches zero, is one of the most fundamental issues in mathematical fluid mechanics. The problem is classified into two categories: the case when the physical boundary is absent, and the case when the physical boundary is present and the effect of the boundary layer becomes significant. The aim of this article is to review recent progress on the mathematical analysis of this problem in each category.Comment: To appear in "Handbook of Mathematical Analysis in Mechanics of Viscous Fluids", Y. Giga and A. Novotn\'y Ed., Springer. The final publication is available at http://www.springerlink.co

    Long-term results of antiviral therapy in patients with chronic hepatitis C with sustained virologic response

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    Aim of investigation. To estimate frequency of late relapses and clinical outcomes in patients with chronic hepatitis C (CHC) with sustained virologic response (SVO) achievement at antiviral therapy (AVT).Material and methods. Overall 208 patients with CHC, including 12 at the stage of liver cirrhosis (LC), who achieved SVO were investigated. Mean duration of the follow-up was 56,1±35,4 months. Standard clinical and laboratory investigation and evaluation of RNA HCV was carried out. In 114 patients RNA HCV and DNA HBV in blood serum and peripheral mononuclear blood cells were studied by polymerase chain reaction (PCR) with fluorescent hybridization detection in «real time» mode (sensitivity of 10 IU/ml for HCV and 5 IU/ml for HBV).Results. In 3 (1,5%) patients late (i.e. over 6 months after AVT) relapses of HCV-infection were observed. Application of ultraresponsive PCR method allowed to reveal relapse half a year prior to its clinical and laboratory manifestation in 2 cases. No data on latent HCVinfection was obtained not in a single case, including patients with relapse of cryoglobulinemia syndrome. A principal cause of elevation of alanine transaminase activity was non-alcoholic steatohepatitis. In one LC patient development of esophageal varicose veins was detected. There were no cases of decompensation of LC, hepatocellular carcinoma and death due to liver disease.Conclusion. At patients who have achieved SVO as a result of AVT, late relapses of HCV-infection are rare and in the majority no disease progression was found. Relapses of cryoglobulinemia syndrome were observed, but data on presence of latent HCV-infection were not received. Highly sensitive PCR methods are rational for assessment of SVO
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