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121.
Summary A mathematical model is proposed to explain the influence of the volume fraction of inoculum on the fermentation time and ethanol productivity in semicontinuous ethanol fermentation of sugar cane blackstrap molasses by pressed yeast.Nomenclature a, b, c, d constants, see equation (5) - Eo initial ethanol concentration - Ef final ethanol concentration - K1, K2, K3 constants, see equation (1) - P ethanol productivity - Pc calculated values of P - Pe experimental values of P - r correlation coefficient - So initial TRS concentration - Sm TRS concentration of the feeding mash - T fermentation time (average of the experimental values) - Tc calculated value of T - Te experimental value of T - TRS total reducing sugars calculated as glucose - Uo initial urea concentration - Um urea concentration of the feeding mash - V reactor working volume - Vi volume of the inoculum - volume fraction of inoculum=Vi/V  相似文献   
122.
Data on 31 genetic systems were obtained for 421 individuals belonging to the Arara, Araweté, Mundurucu, and Jamamadi tribes of northern Brazil. The Jamamadi depart farthest, and the Mundurucu least, from South American Indian averages. These data are analyzed together with those of 24 other Amazonian groups. Genetic distances and corresponding dendrograms indicate a cluster of 14 related tribes living north of the Amazon river. These genetic results show only a modest correlation with linguistic and geographic relationships among these groups.  相似文献   
123.
APGWamide (L-Ala-L-Pro-Gly-L-Trp-NH2) was purified from the ganglia of an African giant snail (Achatina fulica Ferussac). This peptide inhibited (hyperpolarized) more than half of the Achatina neurone types tested. This produced an outward current with the membrane conductance increase of RAPN (right anterior pallial neurone) under voltage clamp. The ED50 of the peptide was 6.2 x 10(-6) M (95% confidence limit: 5.0-7.8 x 10(-6) M) and the Emax was 3.9 +/- 0.2 nA. The effects were due to a membrane permeability increase to K+. The peptide is proposed as an inhibitory neurotransmitter of the Achatina neurones.  相似文献   
124.
This work describes the recovery of an extracellular alkaline protease from fermentation broths of a Bacillus sp ATCC 21536, at pH=10.0 using ultrafiltration (MWCO 100,000) and microfiltration (0.1 m) membranes in hollow fiber devices. The influence of membrane pore size and polymeric material and membrane filtration performance was studied. High protein recoveries and high average flux rates were obtained with polysulfone membranes. A decrease of concentration polarization was obtained, simultaneously with enhancement of filtration flux rate and enzyme recovery by using submicron sized charged particles. These polymers lead to flocculation and adsorption of whole cells and soluble factors from the fermentation broth. The best results were obtaiend by combination of cationic (0.1%) and anionic (0.04%) polymers.  相似文献   
125.
In open-chest rats, alveolar pressure was measured with alveolar capsules connected via pliable tubing to inductive pressure transducers. By means of the interrupter technique during constant-flow inflation, it was possible to determine pulmonary static elastance (Est,L) and tissue and airway resistances (Rdiff,L and Rinit,L, respectively). In eight anesthetized paralyzed mechanically ventilated rats, 118 measurements of Rdiff,L and Est,L were performed over a wide range of flows and tidal volumes. There was excellent agreement between the data calculated using transpulmonary pressures and those computed using capsule pressures, the latter being measured at different points of the lung. In another group of rats studied under the same experimental conditions, two capsules were simultaneously placed on different pulmonary lobes. No regional differences in pulmonary mechanics could be detected in either experiment. In addition, alveolar pressure could also be measured accurately by a catheter inserted into lung parenchyma.  相似文献   
126.
The present investigation was undertaken to evaluate the vagal function of trained (T) and sedentary (S) rats by use of different approaches in the same animal. After 13 wk of exercise training (treadmill for 1 h 5 times/wk at 26.8 m/min and 15% grade), T rats had a resting heart rate (HR) slightly but significantly lower than S rats (299 +/- 3 vs. 308 +/- 3 beats/min). T rats had marked reduction of the intrinsic HR (329 +/- 4 vs. 369 +/- 5 beats/min) after blockade by methylatropine and propranolol. They also exhibited depressed vagal and sympathetic tonus. Baroreflex bradycardia (phenylephrine injections) was reduced, bradycardic responses produced by electrical stimulation of the vagus were depressed, and responses to methacholine injection were decreased in T rats. Therefore several evidences of vagal function impairment were observed in T rats. The resting bradycardia after exercise training is more likely to be dependent on alterations of the pacemaker cells, inasmuch as the intrinsic HR was markedly reduced.  相似文献   
127.
In situ pancreatic DNaseI digestions were used as probes to study the structural organization of facultative and constitutive heterochromatin during both mitotic and meiotic divisions. Three different types of heterochromatic regions from three insect species were chosen for this study. These regions had been previously characterized by in situ treatments with restriction endonucleases (AT and GC rich DNA sequences). Progressive increase in DNaseI concentration (from 10 to 200 ng/ml) or in incubation time (from 5 to 30 min) revealed a specific pattern of sequential digestion of the constitutive heterochromatic regions, the centromeric ones (AT-rich DNA) being the most resistant to DNaseI action. The interstitial C-bands (with AT or GC-rich DNA) were more sensitive to DNaseI, and the band 4.4 from Baetica ustalata was the most resistant of the non-centromeric bands. Similar results were obtained during meiosis, but increased accessibility to DNAseI was observed compared to mitosis. DNA methylation in the non-centromeric band 4.4 of B. ustulata could be responsible for its differential digestion with respect to the remaining intercalar heterochromatin. Facultatively heterochromatic regions (X chromosomes) were found to exhibit a differential response to DNaseI attack from mitosis to meiosis. While they behaved as cuchromatin during mitosis, they were the most resistant together with centromeric heterochromatin regions, during metaphase I and II. The different responses to digestion of the X chromosome and X-derived regions between somatic and meiotic divisions are probably a consequence of the changes in the organization of this chromosome during the facultative heterochromatinization process.  相似文献   
128.
A quantitative in situ assay of yeast α-glucosidase involving permeabilization of the cells by freezing and thawing is described. The assay was applied to different strains in different physiological states and was shown to give results comparable to those obtained with total cell homogenates. The primary advantage of the in situ assay was the possibility of analyzing a large number of samples from the same culture during a growth curve using a very reduced cell mass.  相似文献   
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