Effect of preoperative supplementation with alpha-tocopherol and ascorbic acid on myocardial injury in patients undergoing cardiac operations

Augmentation of antioxidant defenses may help protect tissues against ischemia-reperfusion injury associated with operations involving cardiopulmonary bypass. In this study we examined the effect of pretreating patients with alpha-tocopherol (vitamin E) and ascorbic acid (vitamin C) or placebo on injury to the myocardium. Seventy-six subjects undergoing elective coronary artery bypass grafting participated in a prospective, double-blind, placebo-controlled randomized trial, receiving either placebo or both 750 IU dl-alpha-tocopherol per day for 7 to 10 days and 1 gm ascorbic acid 12 hours before the operation. Plasma alpha-tocopherol concentrations, raised fourfold by supplementation, fell by 70% after the operation in the supplemented group and to negligible levels in the placebo group. There were no significant differences between the groups with respect to release of creatine kinase MB isoenzyme over 72 hours, nor in the reduction of the myocardial perfusion defect determined by thallium 201 uptake. Electrocardiography provided no evidence of a benefit from antioxidant supplementation. Thus the supplementation regimen prevented the depletion of the primary lipid soluble antioxidant in plasma, but provided no measurable reduction in myocardial injury after the operation.     

A study of self poisoning with oral salbutamol--laboratory and clinical features

A review of 35 patients > 60 years of age with odontoid fractures showed that a type II injury (Anderson and D'Alonso) was the most common fracture pattern (82% of cases). On the basis of mechanism of injury and sex incidence, we deduced that osteopenia is a contributory factor in the occurrence of odontoid fractures. A fall in a domestic setting was the cause in 53%. The peg was posteriorly displaced in 88% of type II fractures, and primary union occurred in 23%. The incidence of concomitant spinal cord injury with type II fractures was higher in older patients than it was in those < 60 years of age. The outcome for these patients was largely determined by their neurological status at presentation. Myelopathy as a late complication of nonunion was not observed in nine patients with an average follow-up of 21 months. The data suggest that vigorous attempts to secure both primary union and a sound arthrodesis for non-union are questionable in the elderly except in unusual circumstances.     

Overview of underground coal gasification operations at Chinchilla,Australia

Underground coal gasification (UCG) is a process which converts deep, un-mineable or difficult to mine coal resources into syngas which can then be converted into valuable end products such as electric power, liquid fuels, synthetic natural gas and chemicals. This paper provides a summary of the UCG operations conducted at the Chinchilla Demonstration Facility in Australia, focusing on gasifiers constructed using directional drilling. A number of the experiences and key lessons learned from operating multiple underground gasifiers over several years at the facility are described. Implications for the implementation in commercial projects using UCG are also discussed. Finally, the potential of UCG as a method for producing syngas from deep coal is discussed and some of the challenges and opportunities are summarized.     

Mass-transport processes at the steel-enamel interface

Mass-transport processes at the enamel-steel interface were investigated by studying the rheological properties of the enamel and the microstructure of the enamel-steel interface. The thermophysical properties, e.g., the viscosity and spreading behavior of enamel were measured using the rotating bob and the sessile drop techniques, respectively. The results show that the viscosity of the enamel decreases sharply as the FeO concentration increases from 0 to 25 wt pct, while the contact angle changes with the increasing thickness of the NiO precoat. Microstructural characterization also revealed evidence for the presence of an interfacial gradient force (more specifically referred to as the Marangoni convection) confined within the 0- to 80-μm thickness at the enamel-steel interface. This force is responsible for a convective flow, which determines the formation of flow striae at the interface. The striae act as a sink for evolved gases and provide transport away from the enamel-steel interface. In addition, experimental simulation of Marangoni convection (interfacial-gradient force) was carried out by selectively doping the steel surface with excess Fe₂O₃ powder. The presence of convection flow was confirmed by analyzing the pattern of iron oxide particles dispersed across the surrounding enamel layers. Based on the microstructural characterization and the thermophysical data, we propose a mechanism for mass transport at the glass-steel interface.     

Growth velocity-undercooling relationships and microstructural evolution in undercooled Ge and dilute Ge-Fe alloys

A melt encasement (fluxing) technique has been used to systematically study the velocity-undercooling relationship in samples of pure Ge and Ge doped with 0.01 at % Fe at undercoolings up to 300 K. The apparatus was designed such that it was possible to view the sample throughout the experiment, allowing solidification velocity measurements to be made. These velocity measurements were subsequently correlated with the as-solidified microstructure. From a combination of growth velocity measurements and microstructural characterisation it was possible to identify a change in growth morphology from faceted to non-faceted growth in both the pure metal and the dilute alloy. This transition occurred at a lower undercooling in the dilute alloy (T > 150 K) than in the pure metal (T > 170 K). Spontaneous grain refinement was also observed at T > 210 K in Ge-Fe and at T > 270 K in pure Ge. These transitions are discussed and a mechanisms for the change in growth morphology with small amounts of impurity is suggested.     

Opening the 1.5 mu m window in 1.3 mu m regenerated systems

The authors introduce a novel upgrade technique for currently installed 1.3 mu m regenerated optical transmission systems that can be implemented with minimal disturbance to existing plant. The method uses erbium fibre amplifiers to bypass regenerators thus opening the 1.5 mu m window. The concept is discussed and an experiment reported to illustrate the scheme.<>     

Neuropsychological outcomes in randomized controlled trials of antiepileptic drugs: a systematic review of methodology and reporting standards

PURPOSE: To systematically review the methodology and use of neuropsychological tests in randomized controlled trials (RCTs) of antiepileptic drugs (AEDs) in patients with epilepsy. METHODS: Trial reports were found by searching Medline 1966-1996 and searching through journals by hand. Inclusion and exclusion criteria were applied, and methodological and neuropsychological test data was extracted by using a proforma. RESULTS: 43 reports met our inclusion criteria, representing 40 RCTs. as three RCTs had generated two reports. Twenty-two were actively controlled, and 18 were placebo-controlled studies. Reporting of basic methods such as randomization method was poor. There has been no uniform approach to the use of neuropsychological tests, and a total of 87 has been used. The Stroop Colour Word Test and the Finger Tapping Test were most commonly used, at 13 times each, but were not used or reported in a uniform manner. CONCLUSIONS: Poor reporting of methods and the use of a plethora of neuropsychological tests create great difficulties for anyone wishing to make sense of currently available data. If we are better to understand the neuropsychological effects of AEDs, a more rational approach is needed, for which recommendations are made.     

Using vegetation reflectance variability for species level classification of hyperspectral data

A study was conducted to investigate whether reflectance data from vegetation in a tropical forest canopy could be used for species level discrimination. Reflectance spectra of 11 species were analysed at the scale of the leaf, branch, tree and species. To enhance separation of species-of-interest spectra from the other spectra in the data, the variation in reflectance values for the species-of-interest were used to create a characteristic spectral shape. With a simple algorithm, the resultant shape-space was used as a data filter that correctly discriminated against 94% of the non-species-of-interest trees.     

Structure-property relationships in bainitic steels

Bainitic microstructures can be produced in a variety of steels either as a result of a deliberate attempt to achieve a particular combination of strength and toughness or in response to welding during fabrication. In addition, such microstructures can offer advantages in terms of their resistance to creep or fatigue deformation or susceptibility to hydrogen embrittlement. The relationships among chemical composition, processing, microstructure, and the mechanical properties will be reviewed. Particular emphasis will be placed on recent advances in alloy design. These developments rely on an improved understanding of the mechanisms of bainitic transformation, and the relevance of recent research in this area to the design of new alloy systems will be discussed. Bainitic structures which arise during welding can have a significant and sometimes detrimental effect on the fracture toughness of the welded joint. The fracture toughness of bainitic microstructures in so-called “local brittle zones” in the heat-affected zone and in weld metals and the importance of controlling the bainitic morphology will be considered and the transformation mechanisms discussed. In summary, the aim of this review will be to indicate the prospects for improved microstructural control of structure-property relationships in steels containing a significant proportion of bainite. This paper is based on a presentation made in the symposium “International Conference on Bainite” presented at the 1988 World Materials Congress in Chicago, IL, on September 26 and 27, 1988, under the auspices of the ASM INTERNATIONAL Phase Transformations Committee and the TMS Ferrous Metallurgy Committee.