Administration of corticosterone after the first downshift trial enhances consummatory successive negative contrast.

Rats given access to a 32% sucrose solution and then downshifted to a 4% solution exhibit less contact with the sipper tube than unshifted controls always given access to 4% solution. This phenomenon, called consummatory successive negative contrast, was facilitated in Experiment 1 by a posttrial injection of corticosterone (3 mg/kg) administered immediately after the first downshift trial. Experiment 2 demonstrated that this facilitatory effect of posttrial corticosterone does not occur when administered 3 hr after the first downshift trial. These results support the hypothesis that corticosterone strengthens an aversive emotional component elicited by the surprising downshift in reward magnitude during the initial downshift trial. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Calibration of multiplexed fiber-optic spectroscopy

Large-scale commercial bioprocesses that manufacture biopharmaceutical products such as monoclonal antibodies generally involve multiple bioreactors operated in parallel. Spectra recorded during in situ monitoring of multiple bioreactors by multiplexed fiber-optic spectroscopies contain not only spectral information of the chemical constituents but also contributions resulting from differences in the optical properties of the probes. Spectra with variations induced by probe differences cannot be efficiently modeled by the commonly used multivariate linear calibration models or effectively removed by popular empirical preprocessing methods. In this study, for the first time, a calibration model is proposed for the analysis of complex spectral data sets arising from multiplexed probes. In the proposed calibration model, the spectral variations introduced by probe differences are explicitly modeled by introducing a multiplicative parameter for each optical probe, and then their detrimental effects are effectively mitigated through a "dual calibration" strategy. The performance of the proposed multiplex calibration model has been tested on two multiplexed spectral data sets (i.e., MIR data of ternary mixtures and NIR data of bioprocesses). Experimental results suggest that the proposed calibration model can effectively mitigate the detrimental effects of probe differences and hence provide much more accurate predictions than commonly used multivariate linear calibration models (such as PLS) with and without empirical data preprocessing methods such as orthogonal signal correction, standard normal variate, or multiplicative signal correction.     

Analyzing the interactions and miscibility of silk fibroin/mucin blends

Mucin, a glycoprotein with viscoelastic properties, and silk fibroin, a protein excreted from silkworms with properties of thermal and mechanical resistance, have been probed as building blocks in the design of biomaterials. Aiming to evaluate the interaction and miscibility between mucin and fibroin, we synthesized silk fibroin and mucin (SF/MU) blends for biomedical applications. The morphological analysis of the SF/MU blends showed the presence of two phases, suggesting a partial miscibility between the polymers. The degradation temperature of the SF/MU blends increased with an increase in the silk fibroin content, indicating that silk fibroin contributed to the thermal stability of the blends. The glass transition temperature of the SF/MU blends lay between the values of the pure polymers. The Fourier-transform infrared spectroscopy results pointed out that the interaction between fibroin and mucin occurred between the amine group of silk fibroin and mucin carboxyl and hydroxyl groups. The outcomes of this work provided essential information on the miscibility of the SF/MU blends. These findings will be critical for further studies with fibroin and mucin-based biomaterials, especially in mucoadhesive systems and wound healing applications.     

Gabexate for the prevention of pancreatic damage related to endoscopic retrograde cholangiopancreatography. Gabexate in digestive endoscopy--Italian Group

BACKGROUND: Endoscopic retrograde cholangiopancreatography (ERCP) is associated with elevated levels of pancreatic enzymes and pancreatitis. Gabexate, a protease inhibitor, has been used to prevent pancreatic damage related to ERCP. METHODS: We conducted a multicenter, double-blind comparison of gabexate (1 g given by intravenous infusion starting 30 to 90 minutes before endoscopy and continuing for 12 hours afterward) with placebo (mannitol and sodium chloride, administered in the same fashion). A total of 435 adults scheduled to undergo ERCP and, when indicated, endoscopic sphincterotomy underwent randomization; 17 were excluded from the final analysis for various reasons. The remaining 418 patients (mean age, 60.4 years)--208 in the gabexate group and 210 in the placebo group--were analyzed. Acute pancreatitis was considered to be present if serum amylase or lipase levels (or both) were five times greater than the upper limits of normal in association with the onset of pancreatic pain. RESULTS: After the procedures, 276 patients (66 percent) had elevated pancreatic-enzyme levels; the frequency was similar in the two groups. Mean serum amylase values were higher in the placebo group than in the gabexate group through 24 hours of observation (P=0.03). Twelve patients in the gabexate group and 29 in the placebo group had abdominal pain (6 percent vs. 14 percent, P=0.009). Sixteen patients in the placebo group and five in the gabexate group had acute pancreatitis (8 percent vs. 2 percent, P=0.03). Two patients treated with gabexate and six given placebo had adverse events, all of which resolved. Two patients given placebo died of acute pancreatitis; one was excluded from the evaluation because pancreatitis was present before endoscopy. One patient in the gabexate group died, from a myocardial infarction. CONCLUSION: Prophylactic treatment with gabexate reduced pancreatic damage related to ERCP, as reflected by reductions in the extent but not the frequency of elevated enzyme levels and in the frequency of pancreatic pain and acute pancreatitis.     

Scientific group cohesiveness at the National University of México

Summary We present the results on the relationship between the bonding number (the number of links among the authors of an article) and a measure of group cohesiveness on a Likert-type scale in three research areas, Biotechnology, Mathematics and Physics, at the National University of Mexico (UNAM). We found a difference between disciplines with regard to group size, and although there is little difference between disciplines in cohesiveness, results suggest that there is a direct relationship between the level of cohesiveness and the bonding number in Physics and Biotechnology, but not in Mathematics where the groups are much smaller.     

Deficient Strategic Control of Verbal Encoding and Retrieval in Individuals With Methamphetamine Dependence.

Methamphetamine (MA) dependence is associated with deficits in episodic verbal memory, but the cognitive mechanisms underlying such impairments are not known. The authors evaluated a component process model of episodic verbal memory in 87 persons with MA dependence (MA+) and 71 demographically similar non-MA-using controls (MA-). Compared with MA- controls, MA+ participants demonstrated deficient overall learning, free recall, and utilization of semantic clustering, as well as higher rates of repetitions and intrusions. No between-groups differences were evident on measures of serial clustering, retention, or recognition discrimination. Taken together, these findings indicate that MA dependence is associated with deficient strategic (i.e., executive) control of verbal encoding and retrieval, which is consistent with the sequelae of MA-related prefronto-striatal circuit neurotoxicity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Monitoring pH-dependent conformational changes in aqueous solutions of poly(methacrylic acid)-b-polydimethylsiloxane copolymer based on fluorescence spectra of pyrene and 1,3-bis(1-pyrenyl)propane

Aqueous solutions of poly(methacrylic acid)-b-polydimethylsiloxane copolymer (PMA-b-PDMS), and reference solutions of PMA homopolymer, were studied as a function of pH using fluorescent probes: pyrene (P) and 1,3-bis(1-pyrenyl)propane (P3P). In both polymers the conformational transition of PMA chains at pH>5 was reflected in the sharp increase of the intensity ratio of the first to the third vibronic band in emission spectra of P; an excimer emission appeared for P3P, as well as for P if the probe concentration was higher than its solubility limit in water. The excimer to monomer intensity ratio of both probes is a sensitive indicator of the conformational transitions of polymer chains, but P3P is significantly more sensitive compared to pyrene. The data clearly indicated that the presence of PDMS blocks markedly facilitated the transition, even though the ratio of dimethylsiloxane to methacrylic acid units in the copolymer was low, 1:34. The absence of the P3P excimer emission at pH≈3 was rationalized by assuming that clustering of sections of PMA chains around pyrene moieties imposes an extended conformation of the probe molecule.     

Concave utility, transaction costs, and risk in measuring discounting of delayed rewards.

Research has consistently found that the decline in the present values of delayed rewards as delay increases is better fit by hyperbolic than by exponential delay-discounting functions. However, concave utility, transaction costs, and risk each could produce hyperbolic-looking data, even when the underlying discounting function is exponential. In Experiments 1 (N=45) and 2 (N=103), participants placed bids indicating their present values of real future monetary rewards in computer-based 2nd-price auctions. Both experiments suggest that utility is not sufficiently concave to account for the superior fit of hyperbolic functions. Experiment 2 provided no evidence that the effects of transaction costs and risk are large enough to account for the superior fit of hyperbolic functions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Emulgierf?higkeit von ?thylestern des Sonnenblumenpektins

Zusammenfassung Es wurde nachgewiesen, daß die untersuchten Äthylester (Äthylpektine) wesentlich bessere Emulgiereigenschaften als das Ausgangs-Sonnenblumenpektin haben. Die Dispersität und die Viscosität der Emulsionen erhöht sich mit der Konzentration der Äthylpektine und der Ölphase. Die Stabilität der Emulsionen wird bei steigender Konzentration von Äthylpektin und Ölphase verbessert. Es wurde festgestellt, daß die Emulgierfähigkeiten von Äthylestern des Sonnenblumenpektins auch vom Veresterungsgrad abhängen. Die besten Ergebnisse erzielt man mit Derivaten, die einen Veresterungsgrad von etwa 65% haben.

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Emulsifying properties of ethylesters of sunflower pectin

Summary It has been shown that the studied ethylesters (ethylpectins) have far better emulsifying properties than the initial sunflower pectin.The dispersity, viscosity and stability of the emulsions increase with increasing concentration of the ethylpectins and the oily phase. It has been found that the emulsifying properties of ethylesters of the sunflower pectin depend also on the degree of esterification. Best results are achieved with derivatives which have a degree of esterification of about 65%.

     

Thermal and electrical properties of nitrile‐containing polyimide/BaTiO3 composite films

Polyimide composite films were prepared by mixing the BaTiO₃ particles into poly(amic acid) solution followed by film casting and thermal imidization under controlled temperature conditions. The poly(amic acid) was synthesized by solution polycondensation reaction of 4,4′‐oxydiphthalic anhydride with 2,6‐bis(4‐aminophenoxy)benzonitrile, using N‐methyl‐2‐pyrrolidone as solvent. The surface of BaTiO₃ particles was modified by treating with an aminosilane coupling agent, 3‐aminopropyltriethoxysilane. Fourier transform infrared spectroscopy, X‐ray diffraction and scanning electron microscopy were used to characterize the structure and properties of the composites. The influence of BaTiO₃ content on the composite film properties was evidenced. The films exhibited good thermal stability having the initial decomposition temperature above 520°C. They had stable dielectric properties over large intervals of temperature and frequency. The dielectric constant and the dielectric loss increased with the increase of BaTiO₃ content. The dynamic mechanical analysis and dielectric spectroscopy revealed subglass transitions γ and β. At higher temperature an α‐relaxation that corresponds to the glass transition and a conductivity process were evidenced. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers