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Impact of phonons and spin-orbit coupling on Auger recombination in InAs
Fermentation study for the production of hepatitis B virus pre-S2 antigen by the methylotrophic yeast Hansenula polymorpha.
Various physico-chemical parameters have been studied in order to improve the production of hepatitis B virus pre-S2 antigen (middle surface antigen) by the methylotrophic yeast Hansenula polymorpha. Antigen production was done in two steps: first, production of cells on glycerol (Phase 1), followed by induction of antigen expression with methanol (Phase 2). Dense cultures of H. polymorpha, equivalent to 35-40 g/l (dry weight), were readily obtained in small fermenters using minimal medium containing glycerol as carbon source. Antigen expression in this minimal medium, after induction with methanol, was however, low and never exceeded 1.6 mg/l of culture. Antigen production was greatly enhanced by adding complex organic nitrogen sources along with methanol at induction time; yeast extract was the best of all the sources tested. In shake flasks, antigen production was proportional to yeast extract concentration up to 7% (w/v) yeast extract, it became clear the the nutritional conditions for good antigen expression were different from those for good biomass production. The effects of yeast extract were reproduced in small fermenters: antigen levels reached 8-9 mg/l in medium containing 6% (w/v) yeast extract during induction with methanol. The mechanisms of yeast extract's effects are still unknown but are probably nutritional. The recombinant H. polymorpha strain produced both periplasmic and intracellular antigen. The periplasmic antigen was shown to be present as 20-22-nm particles and was therefore immunogenic. Immunoblotting indicated that part of the pre-S2 antigen was present as a 24-kDa degradation product. These studies have led to a 140-fold increase in volumetric productivity of antigen and to a 4.6-fold increase in specific production
Ethyl 7-(4-bromophenyl)-5-trifluoromethyl-4,7-dihydrotetrazolo[1,5-a]pyrimidine-6-carboxylate
In the title compound, C14H11BrF3N5O2, the pyrimidine ring adopts a flattened envelope conformation with sp
3-hybridized carbon as the flap [deviation = 0.177 (3) Å]. The dihedral angle between tetrazole and bromophenyl rings is 84.3 (1)°. In the crystal, molecules are linked into centrosymmetric dimers by pairs of N—H⋯N hydrogen bonds
Some factors influencing the proportion of periplasmic hepatitis B virus pre-S2 antigen in the recombinant yeast Hansenula polymorpha.
A central composite design (CCD) was used to evaluate, for the purpose of future process optimization, the influence of pH, yeast extract and ammonium chloride concentrations on the proportion of periplasmic hepatitis B pre-S2 antigen in the recombinant yeast Hansenula polymorpha. Each factor was tested at five levels, and a second order polynomial model for the proportion of periplasmic antigen was fitted to the treatment combinations. pH showed the greatest effect: the proportion of periplasmic antigen was greatly increased at the higher pH levels. At the higher pH levels used, the proportion of periplasmic antigen was enhanced by a high concentration of ammonium chloride. Additional experiments have confirmed both the validity of the selected model and the optimal conditions found. A significant correlation was found between the proportion of periplasmic antigen and the total yield of antigen. These results indicated that it should be possible to modulate the distribution of the pre-S2 antigen between the periplasm and the cytoplasm of the yeast
5′-Amino-2-oxo-2′,3′-dihydrospiro[indoline-3,7′-thieno[3,2-b]pyran]-6′-carbonitrile 1′,1′-dioxide
In the title compound, C15H11N3O4S, the dihedral angle between the mean planes of the dihydroindol-2-one (r.m.s. deviation = 0.015 Å) and dihydrothieno[3,2-b]pyran (r.m.s. deviation = 0.011 Å) ring systems is 89.53 (3)°. The crytal packing is consolidated by intermolecular N—H⋯O and N—H⋯N hydrogen bonds, which link the molecules into a two-dimensional network into sheets lying parallel to (100)
Seasonal distribution of active systemic lupus erythematosus and its correlation with meteorological factors
OBJECTIVE: To explore the characteristics of seasonal distribution of active systemic lupus erythematosus (SLE) and the influences of meteorological factors including temperature and humidity on active systemic lupus erythematosus. METHODS: The characteristics of seasonal distribution of active SLE and its correlation with meteorological factors were retrospectively analyzed in 640 patients living in the city of Zhanjiang, China and had active SLE between January 1997 and December 2006. RESULTS: In winter, when there are weaker ultraviolet (UV) rays, the ratio of patients with active SLE to total inpatients was 3.89 %o, which is significantly higher than in other seasons with stronger UV rays, including 2.17 %o in spring, 1.87 0 in summer and 2.12 0 in autumn. The number of patients with active SLE had significant negative correlation with mean temperature and was not significantly related to mean humidity. CONCLUSION: Active SLE has the characteristics of seasonal distribution and is associated with temperature. The mechanism remains to be further studied
Characteristics of the impact pressure of debris flows
Debris flows are common geological hazards in mountainous regions worldwide. Predicting the impact pressure of debris flows is of major importance for hazard mitigation. Here, we experimentally investigate the impact characteristics of debris flows by varying the concentrations of debris grains and slurry. The measured impact pressure signal is decomposed into a stationary mean pressure (SMP) and a fluctuating pressure (FP) through empirical mode decomposition. The SMP of low frequency is caused by the thrusting of bulk flow while the FP of high frequency is induced by the collision of coarse debris grains, revealed by comparing the features of impact pressure spectra of pure slurries and debris flows. The peak SMP and the peak FP first increase and then decrease with the slurry density. The basal frictional resistance is reduced by the nonequilibrium pore-fluid pressure for debris flows with low-density slurry, which can increase the flow velocity and impact pressures. In contrast, the viscous flow of high-density slurry tends to reduce the flow velocity. The peak SMPs are well predicted by the Bernoulli equation and are related to the hydrostatic pressure and Froude number of the incident flow. The peak FPs depend on the kinetic energy and degree of segregation of coarse grains. The maximum degree of segregation occurs at an intermediate value of slurry density due to the transition of flow regime and fluid drag stresses. Our results facilitate predicting the impact pressures of debris flows based on their physical properties
5-Amino-7-(3-chlorophenyl)-3,7-dihydro-2H-thieno[3,2-b]pyran-6-carbonitrile 1,1-dioxide
The title compound, C14H11ClN2O3S, with fused thiophene and pyran rings, was synthesized via the condensation of dihydrothiophen-3(2H)-one 1,1-dioxide and 2-(3-chlorobenzylidene)malononitrile catalysed by triethylamine in ethanol. The thiophene ring adopts an envelope conformation and the pyran ring is planar (r.m.s. deviation = 0.0067 Å). The dihedral angle between the pyran and phenyl rings is 80.8 (1)°. The crystal packing is stabilized by intermolecular N—H⋯N and N—H⋯O hydrogen bonds in which the cyano N and sulphone O atoms, respectively, acting as acceptors
The color gradients of spiral disks in the Sloan Digital Sky Survey
We investigate the radial color gradients of galactic disks using a sample of
about 20,000 face-on spiral galaxies selected from the fourth data release of
the Sloan Digital Sky Survey (SDSS-DR4). We combine galaxies with similar
concentration, size and luminosity to construct composite galaxies, and then
measure their color profiles by stacking the azimuthally averaged radial color
profiles of all the member galaxies. Except for the smallest galaxies (R_{50}<3
kpc), almost all galaxies show negative disk color gradients with mean g-r
gradient G_{gr}=-0.006 mag kpc^{-1} and r-z gradient G_{rz}=-0.018 mag
kpc^{-1}. The disk color gradients are independent of the morphological types
of galaxies and strongly dependent on the disk surface brightness \mu_{d}, with
lower surface brightness galactic disks having steeper color gradients. We
quantify the intrinsic correlation between color gradients and surface
brightness as G_{gr}=-0.011\mu_{d}+0.233 and G_{rz}=-0.015\mu_{d}+0.324. These
quantified correlations provide tight observational constraints on the
formation and evolution models of spiral galaxies.Comment: 20 pages, 5 figures, Accepted for publication in RAA (Research in
Astronomy and Astrophysics
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