N.m.r. line shape-relaxation correlation analysis of bitumen and oil sands

The first results of the analysis of bitumen and oil sands using the recently developed n.m.r. spingrouping technique are presented. The n.m.r. relaxation experiments were carried out on bitumen, and on natural and dried oil sands samples. The results indicate that the spin-grouping can resolve and quantify several components of the samples studied. The bitumen and bitumen fraction of the oil sands are resolved according to their spin-spin relaxation times into three major groups: solid-like (rigid), solid-like (mobile) and semi-liquid. The water in the oil sands exists in two different environments. Tentatively one environment is assigned to be the bridges between the sand grains, while the other is assigned to be the clay surface. One can conclude that with spin grouping of complex mixtures the decomposition (in which components are resolved according to their dynamic state) is possible. The accuracy of such resolution is of the order of a few per cent.     

Comparing word fragment completion and cued recall with letter cues.

Cued recall with word stems as cues and fragment completion rely on different types of letter cues and also differ in the explicit–implicit nature of the retrieval orientation. Despite these differences, variables effective in one task may be effective in the other because both rely on letter cues. Two variables known to affect cued recall were manipulated: Lexical set size (number of words that fit the letter cue) and meaning set size (number of associates generated to the studied words). Across four experiments, subjects in each task were less likely to recover targets from larger lexical sets. However, meaning set size affected cued recall but not fragment completion. These results indicate that fragment completion and letter-cued recall are based on lexical search but that cued recall also involves a semantic search component. Furthermore, type of retrieval cue had a greater effect than type of retrieval orientation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Performance comparison of space-time block coded and cyclic delay diversity MC-CDMA systems

Spatial diversity is a widely applied technique for enhancing wireless system performance since it greatly reduces the detrimental effects of multipath fading. Space-time block codes have been considered the best choice for transmit diversity in narrowband environments, but their use in broadband channels is questionable due to their inability to pick up multipath diversity. However, when used in conjunction with an MC-CDMA system, they achieve not only full spatial but also variable multipath diversity depending on the employed spreading. In comparison, cyclic delay diversity is an attractive approach to achieve spatial and multipath diversity. Its simplicity and conformability with current standards makes it desirable for multicarrier systems. Previous studies suggest that CDD is only advantageous with an outer channel code for OFDM systems. In this article, we compare STBCs and CDD applied to an MC-CDMA system in terms of complexity and performance. It is shown that for an MC-CDMA system, CDD benefits from spreading and channel coding that makes it very competitive with STBCs, particularly since it is applicable to any number of transmit antennas with no loss in rate.     

Biodegradable hollow microfibres to produce bioactive scaffolds

Biodegradable hollow microfibres containing particles loaded with specific active agents can be potentially employed to produce a special kind of substrate for tissue engineering, able to function as a scaffold and at the same time to act as a drug‐releasing system. Biodegradable hollow microfibres based on poly(lactic acid) were produced by a dry–wet spinning procedure. Drug‐loaded microparticles were prepared by a simple oil‐in‐water emulsion and entrapped inside the fibres. The morphology of both fibres and particles was investigated by scanning electron microscopy. The mechanical and thermal properties of the fibres were investigated by tensile tests and differential scanning calorimetry. In vitro tests were performed to evaluate the release of the drug from the fibres loaded with the particles Copyright © 2004 Society of Chemical Industry     

Retaining maximum antioxidative potency of wheat germ oil refined by molecular distillation

A process of physical refining wheat germ oil using the technique of molecular distillation (MD) is presented in this work. Wheat germ oil was obtained from the germ by solvent extraction using hexane and also by cold pressing. The oil extracted with hexane was degummed and bleached before deacidification in order to modify the parameters of phosphorus and color. The goal in carrying out the stage of physical refining by MD was to preserve the maximum amount of original antioxidative potential obtained from extraction of the crude oil. The effect of evaporation temperature of one‐stage MD on the efficiency of free fatty acid elimination was studied. The antioxidant portion was followed by means of analytic determination of tocopherols by high‐performance liquid chromatography. Tocopherol retention up to 98% was achieved in the oil extracted by pressing, and yields of up to 96% were achieved in the oil extracted with hexane. Copyright © 2007 Society of Chemical Industry     

Co- and Ni-exchanged ferrierite: The contribution of synchrotron X-ray diffraction data to siting of TMIs

High-silica zeolites exchanged with transition metal ions (TMIs) are the subject of great interest for their unusual catalytic activity and selectivity. Structural information like coordination and accessibility of TMIs in zeolites are important factors for understanding their catalytic activity. Siting of TMIs in zeolites is typically obtained by spectroscopic (EXAFS, EPR, UV–vis and IR) and computational methods, as in the case of Co-ferrierite. However, some controversy exists in the literature concerning the model for incorporation of bare Co ions in ferrierite. We show here that the results of our synchrotron X-ray powder diffraction studies on Co- and Ni-exchanged ferrierite (Si/Al = 8.5) are in a good agreement with the model of Co siting based on an indirect spectroscopic approach and help to validate this model. By direct structural evidences, a possible explanation for the larger catalytic activity of Co sites in the main channels of ferrierite can be inferred. A combination of data from in situ XRD continuous monitoring of the Co ion migration during calcination and crystal-chemical considerations allows to device a strategy for the design of optimised co-cations containing Co-ferrierite catalysts.     

Immunoelectron localization of mitochondrial F1 factor in cryosections of heart muscle cells

Immunocytochemistry was used to investigate the localization of F1 ATPase in mitochondria of cryosections of adult mouse heart muscle cells. The initial aldehyde fixation was the only denaturation step for antigens. The fine structure was preserved with contrast enhancement as the sections were maintained hydrated, with the advantage that the entire procedure is completed in one working day. The reaction was highly specific, and entire mitochondria were labeled with the Protein A-gold complex. A new analytical technique, electron spectroscopic imaging (ESI), contributed to a better visualization of the localization of the F1 factor.     

Structural Response of Nuclear Containment Shield Buildings with Construction Openings

Steam generator replacement at nuclear power plants requires large construction openings in nuclear containment structures. This study examines the effects of such openings placed in a 61?cm (2?ft) thick dome of a shield building. The dome is cast in two layers, and the limiting cases of the two layers acting as one and the lower layer carrying the entire load are considered. Without openings, the stresses due to dead load in the structure are very low when compared to the material strength. With openings, the loads are easily redistributed around the opening, and the maximum stresses for the conservative case are between three and four and one-half times larger than in the original structure with no openings. The extent of the affected area around the holes is relatively small. Smooth corners in the openings are necessary to avoid high local stress concentrations.     

Pervasive 2007: It's about the User

Pervasive computing is as much about the user as it is about the technology. So, the Fifth International Conference on Pervasive Computing emphasized desirability rather than just feasibility. Featured themes included user benefits, human-computer interaction, group and social interactions, context awareness, finding and positioning people and objects, and personal privacy.