Activation of the hydrogen evolution reaction (HER) in close to pH-neutral electrolytes can be achieved by addition of trivalent cations. This activation has been investigated using steady state polarization, electrochemical impedance spectroscopy (EIS) and chemical analysis of cathode films for yttrium. Several multivalent cations were included in this study, such as Al(III), Mg(II), Y(III), Sm(III), La(III) and Sc(III). In general the more acidic the metal ions the larger is the activation. Metal hydroxide films formed in the alkaline diffusion layer at the cathode surface can have a negative impact on the magnitude of this activation, and therefore complicate the interpretation of the results. The activation corresponds to a transport of metal ion complexes to the electrode surface and the reduction of bound ligand water to form hydrogen. 相似文献
The methodology of three-dimensional quantitative structure-activity relationships (3D-QSAR) has been employed to develop a quantitative model for the relationship between single-cell activities for a large set of analogs of (Z)-5-decenyl acetate, a pheromone component of the turnip moth, Agrotis segetum, and the structural characteristics of the analogs. The method of partial least squares (PLS) projections to latent structures has been used to delineate the relationships between measured activities and chemical structures. The training set includes 42 compounds, and a test set of seven molecules has been employed to assess the predictivity of the model. The model derived is able to calculate the activities of the seven test compounds with an average unsigned error of 0.3, close to the experimental error. Contour maps of regression-like coefficients from transformed PLS components display electronic and nonbonded features of high importance for the observed variation in the activities of compounds in the training set. The contours for the nonbonded (van der Waals) field support previous conclusions that the interaction between the pheromone component and its receptor is characterized by a high steric complementarity. 相似文献
Fusion proteins composed of a cellulose-binding domain fromNeocallimastix patriciarum cellulase A and Candida antarcticalipase B were constructed using different linker peptides. Theaim was to create proteolytically stable linkers that were ableto join the functional modules without disrupting their function.Six fusion variants containing linkers of 444 residueswere expressed in Pichia pastoris and analysed. Three variantswere found to be stable throughout 7-day cultivations. The cellulose-bindingcapacities of fusion proteins containing short linkers wereslightly lower compared with those containing long linkers.The lipase-specific activities of all variants, in solutionor immobilized on to cellulose, were equal to that of the wild-typelipase. 相似文献
The pineal hormone melatonin has been used in clinical trials in patients suffering from AIDS and also as an adjuvant for cancer therapy. Although melatonin has been reported to have beneficial effects in some animal models of immune dysfunction, it remains unknown whether this hormone has any salutary effects on immunity following soft-tissue trauma and/or major blood loss. To study this, soft-tissue trauma (2.5-cm midline laparotomy) and hemorrhagic shock (arterial BP 35 +/- 5 mm Hg) were induced in C3H/HeN mice. The mice were resuscitated after 90 min of hypotension with the shed blood and lactated Ringer's solution. Treatment with saline, vehicle, or melatonin (10 mg/kg BW) subcutaneously was administered in the evening of the day of surgery and again on the following evening. All animals were sacrificed at 48 hr following trauma-hemorrhage and resuscitation to obtain plasma, splenocytes, as well as splenic and peritoneal macrophages (Mphi). The results indicate that melatonin administration after trauma-hemorrhage significantly improved the depressed immune functions, as evidenced by the restoration of Mphi IL-1 and IL-6 release, as well as significantly improved splenocyte IL-2 and IL-3 release and splenocyte proliferative capacity. No differences in circulating corticosterone levels between vehicle- and melatonin-treated animals were observed. This is the first study to show that melatonin, which is reported to be free of adverse side effects, can be considered a safe and effective therapeutic agent for restoring the depressed immunological function after soft-tissue trauma and hemorrhagic shock. 相似文献
The effects of liver dearterialization on the rate of amino acid incorporation into liver and tumor proteins were studied with an in vitro method in seven patients with liver metastases. Before liver dearterialization the incorporation rate was 0.074 +/- 0.020 nmol leucine x mg prot-1 x h-1 in liver tissue and 0.234 +/- 0.049 nmol leucine x mg prot-1 x h-1 in tumor tissue. After dearterialization for 1 h the incorporation rate was reduced to about half of the initial values in both liver and tumor tissue. The vascularity of the tumors was evaluated from preoperative hepatic angiograms. The reduction of the incorporation rate was more pronounced in highly vascularized tumors than in poorly vascularized tumors and liver tissue. The clinical implications of a more pronounced metabolic effect of the dearterialization in high vascularized tumors are discussed. 相似文献
The dependence of the gas response on the gate metal morphology of field-effect gas sensors has been investigated in a new systematic way by using a scanning light pulse technique (SLPT) together with fabrication of metal gates where the metal morphology is continuously varied over the gate area. With the SLPT the local gas response at different points of the gate area can be measured. Furthermore, a mass spectrometric local gas sampling technique has been applied in combination with the local gas response measurements, which gives complementary information about the surface chemistry and how it changes with the morphology of the metal gate.
Three different gate metals, Pd, Pt and Ir, have been studied by analysing the morphology and the gas response to five different gases, H2, NH3, C2H5OH, C2H4 and CH3CHO. Morphological aspects such as crack coverage, concentration of cracks and the length of the crack boundary, have been calculated from acquired scanning electron microscopy (SEM) images. Different possible response mechanisms are discussed in order to explain the observed responses and to understand the role of the morphology and the choice of the catalytic metal.
Only in the case of ammonia a direct correlation between the morphological aspects, e.g. crack coverage, and the response was found. For Pd large changes in the local water pressure close to the metal gate surface have been measured at different parts of the metal gate by using the local gas sampling technique and a correlation is observed with the simultaneously measured gas response. Of the response mechanisms discussed in this contribution only a dissociative mechanism, where hydrogen atoms trapped at the interface between the metal gate and the insulator gives the response of the device, is consistent with all obtained results. 相似文献
This special issue of the International Journal of Computer Vision highlights research on computer vision at the NEC Research Institute. The purpose of this preface is to provide some context to how this work reflects our broader goals and themes of computer vision research at NECI. 相似文献
Disruption to endothelial cell homeostasis results in an extensive variety of human pathologies that are particularly relevant to major trauma. Circulating catecholamines, such as adrenaline and noradrenaline, activate endothelial adrenergic receptors triggering a potent response in endothelial function. The regulation of the endothelial cell metabolism is distinct and profoundly important to endothelium homeostasis. However, a precise catalogue of the metabolic alterations caused by sustained high catecholamine levels that results in endothelial dysfunction is still underexplored. Here, we uncover a set of up to 46 metabolites that exhibit a dose–response relationship to adrenaline-noradrenaline equimolar treatment. The identified metabolites align with the glutathione-ascorbate cycle and the nitric oxide biosynthesis pathway. Certain key metabolites, such as arginine and reduced glutathione, displayed a differential response to treatment in early (4 h) compared to late (24 h) stages of sustained stimulation, indicative of homeostatic metabolic feedback loops. Furthermore, we quantified an increase in the glucose consumption and aerobic respiration in endothelial cells upon catecholamine stimulation. Our results indicate that oxidative stress and nitric oxide metabolic pathways are downstream consequences of endothelial cell stimulation with sustained high levels of catecholamines. A precise understanding of the metabolic response in endothelial cells to pathological levels of catecholamines will facilitate the identification of more efficient clinical interventions in trauma patients. 相似文献
This paper presents an in-depth view of how architects work with maintaining product line architectures at two internationally well-known automotive companies. 相似文献