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151.
152.
Impact of nozzle operation on mass transfer in jet aerated loop reactors. Characterization and comparison to an aerated stirred tank reactor 下载免费PDF全文
Sebastian Weber Sebastian Schaepe Stephan Freyer Michael‐Helmut Kopf Christian Dietzsch 《Engineering in Life Science》2018,18(8):579-588
The impact of mass transfer on productivity can become a crucial aspect in the fermentative production of bulk chemicals. For highly aerobic bioprocesses the oxygen transfer rate (OTR) and productivity are coupled. The achievable space time yields can often be correlated to the mass transfer performance of the respective bioreactor. The oxygen mass transfer capability of a jet aerated loop reactor is discussed in terms of the volumetric oxygen mass transfer coefficient kLa [h?1] and the energetic oxygen transfer efficiency E [kgO2 kW?1 h?1]. The jet aerated loop reactor (JLR) is compared to the frequently deployed aerated stirred tank reactor. In jet aerated reactors high local power densities in the mixing zone allow higher mass transfer rates, compared to aerated stirred tank reactors. When both reactors are operated at identical volumetric power input and aeration rates, local kLa values up to 1.5 times higher are possible with the JLR. High dispersion efficiencies in the JLR can be maintained even if the nozzle is supplied with pressurized gas. For increased oxygen demands (above 120 mmol L?1 h?1) improved energetic oxygen transfer efficiencies of up to 100 % were found for a JLR compared to an aerated stirred tank reactor operating with Rushton turbines. 相似文献
153.
《Bioscience, biotechnology, and biochemistry》2013,77(12):2800-2802
γ-Glutamylmethylamide synthetase and dried baker’s yeast cells were enclosed together in a dialysis membrane tube to produce theanine repeatedly by coupled fermentation with energy transfer. The membrane-enclosed enzyme preparation (M-EEP) formed approximately 600 mM theanine from glutamic acid and ethylamine at a 100% conversion rate. M-EEP maintained its productivity of theanine during six consecutive reactions in a mixture containing NAD+. 相似文献
154.
155.
M.K. Pratten H.C. Cable H. Ringsdorf J.B. Lloyd 《Biochimica et Biophysica Acta (BBA)/General Subjects》1982,719(3):424-430
Polycationic copolymers of vinylpyrrolidone and vinylamine (10:0.77) were prepared, and 125I-labelled with either Bolton-Hunter reagent or methyl 3,5-di-[125I]iodohydroxybenzimidate. The rate of pinocytic capture of the copolymer was compared with that of 125I-labelled polyvinylpyrrolidone, using rat visceral yolk sacs and rat macrophages cultured in vitro as test systems. Whereas polyvinylpyrrolidone was captured entirely by non-adsorptive pinocytosis, the cationic derivative was captured more efficiently, probably because it adsorbs to the cell surface. Copolymer of Mr 120 000 was internalized by macrophages somewhat more rapidly than copolymer of Mr 46 000, but was excluded from the yolk sac. 相似文献
156.
Masahiro Sato Norihiro Tada Reiko Iwase Egon Amann 《Molecular reproduction and development》1993,34(4):349-356
It is a well-known phenomenon that cultured mammalian cells that have been pricked in the presence of foreign DNA can be transformed. This micromanipulation ‘pricking’ technique was applied to mouse blastocysts to determine whether uptake of exogenous DNA would occur in the embryos. The middle region of the inner cell mass (ICM) was pricked three times in each blastocyst in a medium containing a linearized plasmid DNA. When the 60 treated blastocysts were transferred to the uterine horns of pseudopregnant females, 30 developing fetuses (50%) at the mid-gestation stage were obtained. Twenty-two of the 30 fetuses (73%) had less than 1 copy of the foreign DNA per diploid cell, as revealed by polymerase chain reaction (PCR)-Southern analysis, a sensitive technique combined with Southern blot processing of the PCR products. The 8 other fetuses were negative for the foreign DNA. When blastocysts were pricked in the presence of vector DNA coupling E. coli β-galactosidase (β-gal) gene to a mouse metallothionein-I (MT-I) promoter and assessed for β-gal activity histochemically after 1 and 5 days of culture in the presence of 1 μM CdCI2, at least 65% of the embryos exhibited β-gal activity mainly in the ICM region. These results indicate that mouse blastocysts can be transfected with a relatively high efficiency after pricking, and that the introduced gene expression occurs. This approach provides a means of mapping the regulatory elements of genes that are active in the mouse blastocyst ICM, and may be useful in investigating the fate of the ICM cells in an intact blastocyst by labeling them via pricking technique. © 1993 Wiley-Liss, Inc. 相似文献
157.
158.
Krebs M Held K Binder A Hashimoto K Den Herder G Parniske M Kudla J Schumacher K 《The Plant journal : for cell and molecular biology》2012,69(1):181-192
Temporally and spatially defined calcium signatures are integral parts of numerous signalling pathways. Monitoring calcium dynamics with high spatial and temporal resolution is therefore critically important to understand how this ubiquitous second messenger can control diverse cellular responses. Yellow cameleons (YCs) are fluorescence resonance energy transfer (FRET)-based genetically encoded Ca(2+) -sensors that provide a powerful tool to monitor the spatio-temporal dynamics of Ca(2+) fluxes. Here we present an advanced set of vectors and transgenic lines for live cell Ca(2+) imaging in plants. Transgene silencing mediated by the cauliflower mosaic virus (CaMV) 35S promoter has severely limited the application of nanosensors for ions and metabolites and we have thus used the UBQ10 promoter from Arabidopsis and show here that this results in constitutive and stable expression of YCs in transgenic plants. To improve the spatial resolution, our vector repertoire includes versions of YCs that can be targeted to defined locations. Using this toolkit, we identified temporally distinct responses to external ATP at the plasma membrane, in the cytosol and in the nucleus of neighbouring root cells. Moreover analysis of Ca(2+) dynamics in Lotus japonicus revealed distinct Nod factor induced Ca(2+) spiking patterns in the nucleus and the cytosol. Consequently, the constructs and transgenic lines introduced here enable a detailed analysis of Ca(2+) dynamics in different cellular compartments and in different plant species and will foster novel approaches to decipher the temporal and spatial characteristics of calcium signatures. 相似文献
159.
A. K. Pavlov V. N. Shelegedin V. T. Kogan A. A. Pavlov M. A. Vdovina A. V. Tret’yakov 《Biophysics》2007,52(6):640-644
The question about the tolerance of microorganisms to high-temperature heating at the moments when fragments are launched from the surface rocks of cosmic objects and enter an atmosphere is among the major aspects of the problem of life transfer through cosmic space. The heating process in the course of such events was modeled here, and the survival of microorganisms was revealed by the example of two E.coli K12 mutant strains. Samples of these cultures in desiccated state were exposed to short heating pulses. Heating took place under extremely low pressure. It was experimentally showed that bacteria survive at a temperature up to 250°C with duration ~10 s under vacuum conditions, meanwhile the same heating under atmospheric pressure leads to complete sterilization. 相似文献
160.
目的:通过检测IVF-ET患者取卵后血清雌激素水平的变化模式,探讨其在预测妊娠中的意义。方法:纳入因榆卵管因素或男性因素行IVF-ET的患者62例(75个周期)。对行IVF-ET的患者,在取卵后隔日监测血清雌二醇(E_2)水平,并比较其在妊娠组与未孕组的差异。结果:取卵后,血E_2水平在妊娠组与未孕组均迅速降低,在取卵后2,4,6,8 d,两组间无统计学差异。在妊娠周期,血E_2平均水平在取卵后10d降至最低,之后逐渐上升。妊娠组与未孕组之间E_2水平的差异从取卵后10d开始可以检测出(分别为816.4±537.6pg/ml和189.5±69.3pg/ml)(P<0.05)。在未孕周期,10d的E_2水平(189.5±69.3pg/ml)显著低于8d(989.2±581.5pg/ml)(P<0.05)。结论:在取卵后8d和10d连续测2次血E_2水平,有助于早期发现妊娠:妊娠患者的E_2水平在10d出现上升预示妊娠,而10d出现剧陡降时,往往预示妊娠失败。 相似文献