Dopamine and intestinal mucosal tissue oxygenation in a porcine model of haemorrhage

Haemorrhage is associated with intestinal mucosal hypoxia and impaired gut barrier function. Dopamine increases oxygen delivery to the intestinal mucosa and may thus counteract haemorrhage-induced mucosal hypoxia. Jejunal mucosal tissue oxygen tension (mucosal PO2) and jejunal oxygen saturation of mucosal microvascular haemoglobin (mucosal HbO2) were measured in 14 anaesthetized pigs. Seven animals served as controls (group C) and seven received continuous infusion of dopamine 16 micrograms kg-1 min-1 (group D) while 45% of blood volume was removed in three equal increments. Resuscitation was performed using shed blood and fluid. Mean arterial pressure and systemic oxygen delivery decreasing significantly during haemorrhage and returned to baseline after resuscitation in both groups. Mucosal PO2 decreased from 4.4 to 1.7 kPa after haemorrhage (P < 0.01) and further to 1.5 kPa after resuscitation (P < 0.01) in group C whereas group D showed an increase from 3.9 to 5.9 kPa after the start of the dopamine infusion (P < 0.05), but no significant difference from baseline after haemorrhage (2.3 kPa) (ns) or resuscitation (3.1 kPa) (ns). Mucosal HbO2 decreased from 52 to 32% after haemorrhage (P < 0.05) and increased to near baseline (37%) (ns) after resuscitation in group C whereas group D showed no significant changes from baseline (54%) throughout the experiment. Comparison between groups showed higher mucosal PO2 and HbO2 values for group D animals after the start of the dopamine infusion (P < 0.05 each), after the first two steps of haemorrhage (P < 0.01 each) and after resuscitation (P < 0.05 each). We conclude that i.v. dopamine 16 micrograms kg-1 min-1 improved tissue oxygenation of the small intestinal mucosa during moderate haemorrhage and subsequent resuscitation.     

美欧清洗工艺之比较

清洗技术受到全球和地区相关行业上下游技术的影响,并随其不断发展.清洗技术因地而异,不同国家和地区之间的清洗工艺存在一定差别,而这些差别主要是由地方市场因素和法律因素决定的. 　　……     

Low Temperature Elastic Constants of Polycrystalline MgB2

We have used a resonant ultrasound spectroscopy technique to measure the bulk and shear modulus of fully dense, polycrystalline MgB₂ between 4 and 300 K. Both moduli show good agreement with published first principle calculations. The internal friction shows a broad maximum around 40 K.     

The adsorption/impregnation of catalytic precursors on pure and composite oxides

Three intrinsically connected phenomena occur during adsorption/impregnation of aqueous electrolytes onto oxide carriers. They are: pH-dependent development of surface charge carriers on the oxide; pH-dependent aqueous speciation of catalytic precursors; surface adsorption by complexation and coordination. Modeling of these processes yields basic thermodynamic properties of the adsorbed phase, which could provide useful information of the catalytic properties of the metal, support, and reveal metal-support interactions, thus contributing to design criteria for supported-metal catalysts.

The spectrum of catalytic systems that can be studied using the above approach is greatly extended when both pure and composite oxide carriers are considered. This presentation will focus on three metal/support systems, each of which provides results of both practical and fundamental importance.     

A New Method for Comparing Orthonasal and Retronasal Olfaction.

Odors seem to be perceived differently when presented ortho- or retronasally. In this study, stimuli of controlled concentration and duration were applied in either the anterior nasal cavity or epipharynx by means of air-dilution olfactometry. Stimulus concentration was monitored in the olfactory cleft. In Experiment 1, odor thresholds to a food (chocolate) and a nonfood (lavender) odor were lower for orthonasal, compared with retronasal, stimulation. In Experiment 2, intensity ratings to suprathreshold odor concentrations were significantly higher for orthonasal than for retronasal stimulation with hydro- hydrogen sulfide, but not phenyl ethyl alcohol. Accordingly, amplitudes and latencies of olfactory event-related gen potentials to retronasal stimuli were found to be smaller and prolonged, respectively. This indicates differential processing of olfactory stimuli presented through the retronasal or orthonasal routes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Credibility and applicability of virtual reality models in design and construction

In this paper, we present the findings from an extensive study of the use of virtual reality (VR) models in large construction projects. The study includes two parts: The first part presents a quantitative questionnaire designed to investigate how VR models are experienced and assessed by the workforce at a building site. The second part includes a qualitative field survey of how VR models can be applied and accepted by professionals in the design and planning process of a large pelletizing plant. Through mainly studying persons who had little or no experience with advanced information technology (IT), we hoped to reveal the attitudes of the average person working at a construction site rather than of an IT expert. In summary, the study shows that the VR models in both projects have been very useful and well accepted by the users. Today’s information flow is, from a general point of view, considered to be insufficient and the hypothesis is that using VR models in the construction process have the potential to minimize waste of resources and improve the final result.     

Near-wall porosity characteristics of fixed beds packed with wood chips

Packed beds of fuel wood chips are commonly found in thermal conversion processes such as combustion or gasification. Wood chips in particular are mostly used as fuel for small-scale domestic heating boilers but also for commercial-scale combustion units. The characterization of spatial voidage distribution inside the wood chip beds is of great importance for flow and reactor modelling. This study focuses on the radial porosity variations of cylindrical beds of three different types of commercially available wood chips including chips classified as G30 size class. The conventional technique of consolidating packed beds with a resin was chosen as the experimental procedure. The radial voidage distribution in different cylindrical beds is determined by image analysis of sections of the solidified packings. Additionally, a packing of monosized spheres was investigated in order to assess the selected procedure in comparison with widely available literature data for spheres. The results are discussed and summarized in a mathematical expression correlating the radial voidage distribution depending on average wood chip size, packing core porosity and dimensionless distance from the tube wall.     

On the Locus of Speed-Accuracy Trade-Off in Reaction Time: Inferences From the Lateralized Readiness Potential.

Lateralized readiness potentials (LRPs) were used to determine the stage(s) of reaction time (RT) responsible for speed-accuracy trade-offs (SATs). Speeded decisions based on several types of information were examined in 3 experiments, involving, respectively, a line discrimination task, lexical decisions, and an Erikson flanker task. Three levels of SAT were obtained in each experiment by adjusting response deadlines with an adaptive tracking algorithm. Speed stress affected the duration of RT stages both before and after the start of the LRP in all experiments. The latter effect cannot be explained by guessing strategies, by variations in response force, or as an indirect consequence of the pre-LRP effect. Contrary to most models, it suggests that SAT can occur at a late postdecisional stage. (PsycINFO Database Record (c) 2010 APA, all rights reserved)