Carbon nanotubes--the route toward applications   总被引：4，自引：0，他引：4  

Baughman RH  Zakhidov AA  de Heer WA 《Science (New York, N.Y.)》2002,297(5582):787-792

Many potential applications have been proposed for carbon nanotubes, including conductive and high-strength composites; energy storage and energy conversion devices; sensors; field emission displays and radiation sources; hydrogen storage media; and nanometer-sized semiconductor devices, probes, and interconnects. Some of these applications are now realized in products. Others are demonstrated in early to advanced devices, and one, hydrogen storage, is clouded by controversy. Nanotube cost, polydispersity in nanotube type, and limitations in processing and assembly methods are important barriers for some applications of single-walled nanotubes.  相似文献   

Spatial extent and consequences of black bass (Micropterus spp.) invasion in a Cape Floristic Region river basin          下载免费PDF全文

Johannes A. Van Der Walt  Olaf L. F. Weyl  Darragh J. Woodford  Frans G. T. Radloff 《水产资源保护:海洋与淡水生态系统》2016,26(4):736-748

The biochemical differentiation between Salmonella and Citrobacter     

M L van der Walt  H C Steyn 《The Onderstepoort journal of veterinary research》1989,56(4):263-269

A number of bacterial isolates which could not be identified as either Salmonella or Citrobacter by conventional biochemical tests and could not be typed as Salmonella with available antisera, were further examined biochemically and by lysis with phage Felix 0.1. Glycerol-positive salmonellae and lysine-positive citrobacters were encountered, which could be confused with the other genus, but when the reactions of such strains were examined in the other tests, accurate identifications could be done. Of the tests examined, glycerol fermentation, the beta-galactosidase test, lysine decarboxylation, sorbose fermentation, galacturonate fermentation and lysis by the phage could be used in the differentiation. These tests in combination, rather than 1 or 2 single tests gave reliable and conclusive differentiation.  相似文献   

An experimental Schistosoma mattheei infection in man     

C T Wolmarans  K N de Kock  M P van der Walt 《The Onderstepoort journal of veterinary research》1990,57(4):211-214

Certain aspects of the immune response of a male experimentally infected with 3-day old cercariae of a pure field strain of Schistosoma matheei were investigated. Among others, aspects such as the reaction of eosinophils, neutrophils and blood platelets after infection, were included in the study. The involvement of IgG and the cross reaction between these antibodies and S. haematobium and S. mansoni were also investigated. The phenomenon that the cercariae were, 3 days after shedding, still capable of penetrating the skin causing an inflammatory response was studied. The results lend some support to the surmise that a pure S. mattheei infection in humans is incapable of any egg production.  相似文献   

Promising chimpanzee     

Burghardt GM 《Science (New York, N.Y.)》1975,189(4208):1042

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The ratio of cardiopulmonary blood volume to stroke volume as an index of cardiac function in horses     

M N van Aarde  A Littlejohn  J J Van der Walt 《Veterinary research communications》1984,8(4):293-302

A method was developed for determining the ratio of cardiopulmonary blood volume to stroke volume, in horses. The radioisotope 99 Tc (technetium 99m pertechnetate) was injected into the jugular vein as a bolus, which was then detected in the right and left ventricles consecutively by a scanning device consisting of a Na I crystal, a collimator, an amplifier and a discriminator. The radiocardiogram (RCG) and the ECG were recorded simultaneously by a two-channel writing device. The ratio of cardiopulmonary blood volume to stroke volume (cardiopulmonary flow index = CPFI) was then determined from the RCG and ECG tracings. Five categories of horses were examined, viz. Thoroughbreds in training, showjumpers in training, horses not in training, horses with cardiovascular disease and horses with chronic lung disease. The mean CPFI of the above categories were respectively 7.0 +/- 0.39, 7.3 +/- 0.45, 6.7 +/- 0.61, 9.8 +/- 1.30 and 6.2 +/- 0.47. The mean CPFI of the subjects with heart disease was significantly greater than the mean values of the other four categories (P less than 0.001). It was concluded that the CPFI was a reproducible physiological parameter in horses and that the value was significantly increased in our series of subjects with heart disease.  相似文献   

Sees global standards as solution to microchip frustration     

Ingwersen W 《Journal of the American Veterinary Medical Association》2002,220(11):1610

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Phage types of Salmonella enterica serovar Enteritidis isolated in South Africa from 1991-1995     

Maré L  Van Der Walt ML  Dicks LM 《The Onderstepoort journal of veterinary research》2000,67(2):129-133

A total of 615 strains of Salmonella enterica serovar Enteritidis (SE), received from 1991-1995 at the Onderstepoort Veterinary Institute (OVI), were phage typed. Most SE isolates (54,7%) originated from poultry followed by humans (28,5 %) and poultry eggs (9,6 %). Phage type 34 was the most prevalent (40,5 %) of all isolates, followed by phage type 4 (33,8 %). Other phage types identified were 1, lb, 4a, 7, 7a, 9a, 14, 24, 24var and 35 (in total 2,4% of isolates). Most isolates of SE were received from the Western Cape Province (47,4%) and Gauteng (22,3%). In poultry phage type 4 was dominant, but in humans, eggs, goats, ducks, sheep, pigs and rabbits, phage type 34 was the dominant type. It appeared as if the poultry-associated epidemic of SE in South Africa that occurred from 1991-1995 originated in the Western Cape Province during 1991 amongst poultry and then spread from there to humans and eggs and then to the rest of the country, where it emerged during 1993. Results indicate that phage type 34 was the dominant phage type from 1991-1993, but during 1994-1995 its presence declined. During this latter period the presence of phage type 4 increased. This may suggest that two smaller epidemics consisting of the two different phage types might have been responsible for the epidemic that occurred from 1991-1995.  相似文献   

Personality and academic performance of three cohorts of veterinary students in South Africa     

van der Walt HS  Pickworth G 《Journal of veterinary medical education》2007,34(3):356-365

To aid in selecting students for admission to undergraduate veterinary training, admissions procedures often take into account students' previous academic performance as well as the results of an interview. The study reported here investigated the relationship between personality and academic success. Students from three entry cohorts to the second year of study of a six-year BVSc program at the University of Pretoria completed the 16 Personality Factor Questionnaire. A meta-analytic approach was used to estimate the relationship between academic performance in two major final-year subjects and academic performance on entry, an interview score, and the personality factors. The study confirmed the value of previous academic performance and the interview in selecting students for the veterinary degree program. The findings also indicate that the inclusion of a measure of intellectual ability could be of value. The value of various personality characteristics in predicting good study habits and examination performance is highlighted by the study results: students were more successful if they were conscientious, emotionally stable, socially adept, self-disciplined, practical rather than imaginative, and relaxed rather than anxious. It appears worthwhile to consider including an appropriate personality questionnaire in the selection process to improve the accuracy of predictions of students' success. A sound personality make-up will not only increase the likelihood of academic success but should also be beneficial in the successful management of a veterinary practice and in enjoying veterinary science as a career.  相似文献   

Dry forests in the Southern Interior of British Columbia: Historic disturbances and implications for restoration and management     

Walt Klenner  Russ Walton  André Arsenault  Laurie Kremsater 《Forest Ecology and Management》2008

We critically examine the hypothesis that dry forests in southern British Columbia evolved in the context of a low-severity fire-dominated disturbance regime, that fire suppression has led to ecological conditions which are radically different from the past, and that “restoration” initiatives are required to re-establish former ecological conditions. Four sources of information were used to infer historic disturbance regimes and forest condition and to quantify the nature of disturbance since the early 1900s: (1) patterns of annual and seasonal weather and lightning strikes, (2) topographic variability, (3) records of wildfire, insect attack, and timber harvesting practices, and (4) early systematic forest surveys.  相似文献