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Liquid/liquid extraction: Applications and choice of solvent . The significance of liquid/liquid extraction has been steadily increasing in recent years as more and more stringent demands are made on the purity, availability, and environmental safety of chemical products. The use and success of this separation process are critically dependent upon the choice of the right extraction agent. Whereas solvent choice was previously mainly empirical, it is now possible to establish the suitability of a given solvent with the aid of molecular-thermodynamic data. This is demonstrated for the extraction of aromatic compounds. The article closes with an account of the formation and stability of emulsions.  相似文献   
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The septate gregarine parasites of flour beetles (Tribolium spp.) include Gregarina minuta Ishii, 1914, a relatively small species in which both primite and satellite possess an obvious protomerite, and a larger species that lacks the satellite protomerite. The latter species has been placed in the genera Didymophyes and Hirmocystis by various authors, but studies reported here demonstrate that this species, herein described as Gregarina triboliorum, exhibits early pairing and produces oocyst chains, both characteristics of the genus Gregarina. The oocysts of this new species are described for the first time. In addition, experimental infections using oocyst from single gametocysts reveal that oocyst chain number is variable but is typically 1, 2, or 4. Prior experiments involving a related beetle, Tenebrio molitor, demonstrated extreme host specificity within the 4 Gregarina species parasitizing larval and adult hosts. However, G. triboliorum is not limited either stadially or specially, infecting both adults and larvae of Tribolium confusum and Tribolium castaneum.  相似文献   
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In this paper, the impact of lumped elements connected to the power-bus of high-speed printed circuit boards is investigated and a computationally efficient expression of the resulting input impedance is derived. This result builds the theoretical basis of a novel technique suppressing cavity-mode resonances within the power-bus using discrete capacitors. Guidelines for an optimized selection and placement of these capacitors are specified. The theoretical results are well confirmed by measurements.  相似文献   
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Nonhomologous DNA end joining (NHEJ) is the major pathway for repairing double-strand DNA breaks. V(D)J recombination is a double-strand DNA breakage and rejoining process that relies on NHEJ for the joining steps. Here we show that the targeted disruption of both DNA ligase IV alleles in a human pre-B cell line renders the cells sensitive to ionizing radiation and ablates V(D)J recombination. This phenotype can only be reversed by complementation with DNA ligase IV but not by expression of either of the remaining two ligases, DNA ligase I or III. Hence, DNA ligase IV is the activity responsible for the ligation step in NHEJ and in V(D)J recombination.  相似文献   
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Randomly assigned 67 phobic 6-15 yr. olds to a 2 * 3 factorial, repeated-measures, covariate design which included 2 male therapists and 3 time-limited treatments: reciprocal inhibition, psychotherapy, and waiting list control. Following 24 sessions or 3-mo wait and at 6-wk follow-up, Ss were reassessed by an independent evaluator and by parents. Results indicate a significant effect due to time and S's age. Clinical evaluation, using initial scores as the covariate, showed no effects of treatment or therapist. Parents reported treatment effects for both target fear and general fear behavior. Therapies were equally efficient, and all treatment effects were achieved with Ss aged 6-10. (48 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
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The protein encoded by the pancreatic colipase (CLPS) gene is an essential cofactor needed by pancreatic triglyceride lipase (PNLIP) for efficient dietary lipid hydrolysis. Since the inhibition of lipase activity was shown to reduce the incidence of type 2 diabetes mellitus, we tested the hypothesis that genetic variations in the CLPS and PNLIP genes are associated with type 2 diabetes; 47 unrelated subjects were screened for polymorphisms of the CLPS and PNLIP genes. A nested-case control study of 192 incident type 2 diabetes subjects and 384 sex- and age-matched controls taken from the European Prospective Investigation into Cancer and Nutrition Potsdam Cohort (EPIC) was employed for association studies. The Metabolic Intervention Cohort Kiel (MICK) consisting of 716 males was used for verification. A novel putative functional polymorphism (Arg109Cys) was identified in the CLPS gene. The frequencies of the Arg/Cys genotype were 2.6% in EPIC and 2.2% in MICK study subjects. No homozygotes for the Cys/Cys genotype were found in either study population. Logistic regression analysis showed a statistically significant association of the Arg/Cys genotype with an increased risk of type 2 diabetes. The odds ratios estimated by the model were 3.75 (95%CI = 1.13-12.49, p = 0.03) in EPIC and 4.86 (95%CI = 1.13-20.95, p = 0.03) in MICK. No comparable associations were found with other traits of the insulin-resistance syndrome (e. g.; body mass index, waist to hip ratio). In conclusion, we obtained evidence in two German Caucasian study populations that the variant of the rare CLPS Arg109Cys polymorphism might contribute to increased susceptibility of type 2 diabetes.  相似文献   
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