402 research outputs found
Vertical thermal structure of the Venus atmosphere from temperature and pressure measurements
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.
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
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Laguncularia racemosa phenolics profiling by three-phase solvent system step-gradient using high-performance countercurrent chromatography with off-line electrospray mass-spectrometry detection
Copyright: © 2021 by the authors. The detailed metabolite profiling of Laguncularia racemosa was accomplished by high-performance countercurrent chromatography (HPCCC) using the three-phase system n-hexane– tert-butyl methyl ether–acetonitrile–water 2:3:3:2 (v/v/v/v) in step-gradient elution mode. The gradient elution was adjusted to the chemical complexity of the L. racemosa ethyl acetate partition and strongly improved the polarity range of chromatography. The three-phase solvent system was chosen for the gradient to avoid equilibrium problems when changing mobile phase compositions encountered between the gradient steps. The tentative recognition of metabolites including the identification of novel ones was possible due to the off-line injection of fractions to electrospray ionization mass spectrometry (ESI-MS/MS) in the sequence of recovery. The off-line hyphenation profiling experiment of HPCCC and ESI-MS projected the preparative elution by selected single ion traces in the negative ionization mode. Co-elution effects were monitored and MS/MS fragmentation data of more than 100 substances were used for structural characterization and identification. The metabolite profile in the L. racemosa extract comprised flavonoids, hydrolysable tannins, condensed tannins and low molecular weight polyphenols.Newton Advanced Fellowship project financed by the Royal Society of the United Kingdom
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New Insight into Organomineral Interactions in Soils. The Impact of Clay-Size Peat-Derived Organic Species on the Structure and the Strength of Soil Silt Aggregates
Data Availability Statement:
The data presented in this study are available on request from the corresponding author. The data are not publicly available due to requiring specific software to view the data files. Most of the data are presented within this publication in the figures.Knowledge of the effects of different organic species on soil structure and strength is gained mostly from experiments on natural soils amended with organic substances of various particle sizes, pH, ionic composition, and inorganic impurities. It greatly diversifies the experimental results and shadows individual effects of organic amendments. Therefore, to look for a clearer view, we examined the impact of HCl-washed clay-size organic species: peat, humic acids, residue after humic acid extraction, and two biochars, all derived from the same peat and having similar particles, on the structure and strength of artificial soil silt aggregates using mercury intrusion porosimetry, bulk density measurements, SEM, and uniaxial compression. Bulk density increased due to humic acid addition and decreased for the other amendments. The total pore volumes behaved oppositely. All organic substances except humic acid decreased the pore surface fractal dimension, indicating a smoothening of the pore surface. Humic acid appeared to occupy mostly the spaces between the silt grains skeleton, while the other species were also located upon silt grains. The latter effect was most evident for 600 °C heated biochar. Humic acid, peat, and the residue after humic acid extraction improved mechanical stability, whereas both biochars weakened the aggregates, which means that bulk density plays a smaller role in the mechanical stability of granular materials, as it is usually considered. A new equation relating maximum stress and the amount of the organic additives was proposed.Funded in part by the National Science Centre, Poland within an Opus 15 Project 2018/29/B/ST10/01592 Effect of minerals and different forms of organic carbon on structure, porosity and mechanical and water stability of soil aggregates—model studies. The full APC waiver for this paper was granted and approved by the editorial office of “Agriculture” MDPI Journal
Separation of Oligosaccharides from Lotus Seeds via Medium-pressure Liquid Chromatography Coupled with ELSD and DAD
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
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
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 μm gate length, In<sub>0.75</sub>Ga<sub>0.25</sub>As channel, thin body n-MOSFET on InP substrate with transconductance of 737μS/μm
The first demonstration of implant-free, flatband-mode In<sub>0.75</sub>Ga<sub>0.25</sub>As
channel n-MOSFETs is reported. These 1 μm gate length
MOSFETs, fabricated on a structure with average mobility of
7720 cm<sup>2</sup>/Vs and sheet carrier concentration of 3.3×10<sup>12</sup> cm<sup>-22</sup>,
utilise a Pt gate, a high-k dielectric (k≈20), and a δ-doped
InAlAs/InGaAs/InAlAs heterostructure. The devices have a typical
maximum drive current (I<sub>d,sat</sub>) of 933 μA/μm, extrinsic transconductance
(g<sub>m</sub>) of 737 μS/μm, gate leakage (I<sub>g</sub>) of 40 pA, and on-resistance
(R<sub>on</sub>) of 555 Ωμm. The g<sub>m</sub> and R<sub>on</sub> figures of merit are the
best reported to date for any III-V MOSFET
The Inviscid Limit and Boundary Layers for Navier-Stokes Flows
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
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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