Self-oriented regular arrays of carbon nanotubes and their field emission properties

The synthesis of massive arrays of monodispersed carbon nanotubes that are self-oriented on patterned porous silicon and plain silicon substrates is reported. The approach involves chemical vapor deposition, catalytic particle size control by substrate design, nanotube positioning by patterning, and nanotube self-assembly for orientation. The mechanisms of nanotube growth and self-orientation are elucidated. The well-ordered nanotubes can be used as electron field emission arrays. Scaling up of the synthesis process should be entirely compatible with the existing semiconductor processes, and should allow the development of nanotube devices integrated into silicon technology.     

Seeking Mathematical Strategies in Sperm Function Analysis: Between Scylla and Charybdis?

During the last decades, essential progresses in reproductive biotechnology were achieved, implying development of special spermatological techniques. The major problem was to set up simple, rapid, precise and adequate evaluation methods. The key aspect to be considered in all assays of sperm fertilizing function is capacitation. As not all spermatozoa respond to fertilizing conditions in a similar manner, it seems to be logical to assess samples via their response to these specific conditions. For the spermatological practice, the sensitivity of methodology for assessment and analysis of data with respect to differences in individual response, in heterogeneity of the population, and proper temporal characterization of the response is crucial for the improvement of evaluation procedures. Currently, most used statistical analytical tools in spermatology do not always fulfil these essential sensitivity requirements. We structured our paper concerning different fields of mathematical science (distribution analysis, fractal geometry, functional approximation and differentiation) related to the modern insights in sperm function analysis. The spectrum of methods we are going to review in this paper is restricted to basic ideas to illustrate how the accuracy and sensitivity of sperm evaluation assays may be improved by applying adequate elementary tools of the mathematical analysis.     

Efficacy of a cold-adapted, intranasal, equine influenza vaccine: challenge trials.

A randomised, controlled, double-blind, influenza virus, aerosol challenge of horses was undertaken to determine the efficacy of a cold-adapted, temperature sensitive, modified-live virus, intranasal, equine influenza vaccine. Ninety 11-month-old influenza-na?ve foals were assigned randomly to 3 groups (20 vaccinates and 10 controls per group) and challenged 5 weeks, 6 and 12 months after a single vaccination. Challenges were performed on Day 0 in a plastic-lined chamber. Between Days 1 and 10, animals were examined daily for evidence of clinical signs of influenza. Nasal swabs for virus isolation were obtained on Day 1 and Days 1 to 8 and blood samples for serology were collected on Days 1, 7 and 14. There was no adverse response to vaccination in any animal. Following challenge at 5 weeks and 6 months, vaccinates had significantly lower clinical scores (P = 0.0001 and 0.005, respectively), experienced smaller increases in rectal temperature (P = 0.0008 and 0.0007, respectively) and shed less virus (P<0.0001 and P = 0.03, respectively) over fewer days (P<0.0001 and P = 0.002, respectively) than did the controls. After the 12 month challenge, rectal temperatures (P = 0.006) as well as the duration (P = 0.03) and concentration of virus shed (P = 0.04) were significantly reduced among vaccinated animals. The results of this study showed that 6 months after a single dose of vaccine the duration and severity of clinical signs were markedly reduced amongst vaccinated animals exposed to a severe live-virus challenge. Appropriate use of this vaccine should lead to a marked reduction in the frequency, severity and duration of outbreaks of equine influenza in North America.     

玉米花粉寿命及有效控制花粉飘逸的隔离距离研究

花粉是玉米基因飘逸的重要载体。研究了花粉活力的持续时间和有效控制基因飘逸的隔离距离。在花药刚开裂时采集花粉,置于薄膜层上,放在室外自然条件下保存,每隔一定时间对采集的花粉进行目测和授粉．通过对花粉的目测评判和计算结实率评估花粉活力。试验花粉源区域4000m^2,在其周围不同距离的地方种植若干玉米小区,每个小区面积为12．8m^2,以测定隔离距离的有效性。作为花粉源的玉米材料包含可用于测定花粉飘逸的叶色标记或种子标记。由于大气压不同,花粉可在花药开裂后1～2小时内保持活力。假定花粉以当地下午平均最大风速直线传播,并可在2小时内保持花粉活力,且忽略花粉沉降率因素,理论上讲,具有活力的花粉可以传播的最大距离为32km。试验结果是在离花粉源100m发生了一定数量的异花授粉,离花粉源200m处有个别异花授粉发生。离花粉源300m处没有异花授粉发生。试验结果与玉米花粉不耐干燥并具高沉降速率的结论一致。试验结果表明距离隔离是控制玉米因授粉而发生基因飘逸的有效方法。     

Scientific uncertainty and the assessment of risks posed by non-native freshwater fishes

The introduction of non‐indigenous plants, animals and pathogens is a pressing global environmental challenge. Although not all introduced species become established and the fraction of those that do often have little appreciable effect on their new ecosystems, many others exert significant ecological, evolutionary and economic impacts. Stimulating further debate, Gozlan [Fish and Fisheries (2008) Vol. 9, pp. 106–115] argued that the majority of intentional freshwater fish introductions associated with aquaculture (fish species providing societal benefits) have not been reported as having an ecological impact. We find little to argue with his suggestion that low risk of ecological impact coupled with high market value encourages further introductions. But do we have an adequate understanding of the ecological risks associated with fish introductions to support such decisions? Indeed, resource managers and decision makers require some scientific knowledge to support their management actions; without this information, a precautionary approach is the only sensible course of action. The precautionary approach implies that the lack of scientific certainty is reason enough for postponing intentional introduction of non‐native species to avoid potentially serious or irreversible harm to the environment. Here, we suggest that we actually know very little about ecological impacts associated with fish introductions and that it would be therefore wholly inappropriate to equate a lack of data with a conclusion of ‘no impact’. We discuss four major challenges for enhancing the assessment of risks posed by non‐native freshwater fishes in the face of scientific uncertainty and highlight research opportunities and some alternative approaches for confronting these challenges in the future.     

PCR detection and analysis of Pasteurella multocida from the tonsils of slaughtered pigs in Vietnam

A total of 36 tonsil swab samples were collected from healthy swine prior to slaughter at the abattoirs in Can tho and Tien giang provinces of Southern Vietnam. The presence of Pasteurella multocida in these samples was detected by the combination of direct cultivation and isolation, mouse inoculation and the polymerase chain reaction (PM-PCR). P. multocida was detected in 16 samples by PCR, with 17 strains ultimately isolated. All samples were negative for serogroup B by HSB-PCR and conventional serotyping, with isolates identified as A:3, D:1 or D:3. In addition, all samples were determined to be negative for the P. multocida toxin (PMT). Characterisation of isolated P. multocida by REP-PCR and biotyping revealed nine distinct REP profiles and seven biotypes among the 17 isolates. Some correlation was seen with P. multocida isolated from a previous Australian outbreak of acute swine pasteurellosis, and those isolated from fowl cholera outbreaks in Vietnamese poultry.     

Protein Composition of Seminal Plasma in Fractionated Stallion Ejaculates

Seminal plasma (SP) contains several types of compounds derived from the epididymides and accessory glands. The aim of this study was to examine the protein composition of different ejaculate fractions. Trial I: fractionated ejaculates were collected from two normal and two subfertile stallions. Samples containing pre‐sperm fluid and the first sperm‐rich jets (HIGH‐1), the main sperm‐rich portion (HIGH‐2), the jets with low sperm concentrations (LOW), and a combined whole‐ejaculate (WE) sample was centrifuged, and the SP was filtered and frozen. A part of each SP sample was stored (5°C, 24 h) with spermatozoa from HIGH‐2 and skim milk extender. Sperm motility was evaluated after storage in extender mixed with the stallion’s own SP or SP from one of the other stallions (sperm from a normal stallion stored in SP from a subfertile stallion and vice versa). Protein composition was analysed using reverse‐phase liquid chromatography (RP‐HPLC), N‐terminal sequencing and mass spectrometry. The area‐under‐the‐curve (AUC) was used for quantitative comparison of proteins within fractions. Trial II: semen samples were collected from seven stallions. Fractions with the highest (HIGH) and lowest (LOW) sperm concentrations and WE samples were examined using SDS‐PAGE and densitometry. No significant differences emerged between fractions in the AUC‐values of the Horse Seminal Protein‐1 (HSP‐1) and HSP‐2 peaks, or the peak containing HSP‐3 and HSP‐4 (HSP‐3/4). Levels of HSP‐1, HSP‐2 and HSP‐3/4 were not significantly correlated with total sperm motility, progressive sperm motility or average path velocity after storage. Significant differences between ejaculate fractions in the amount of different protein groups present in SP were not found in Trial I; but in Trial II, the proteins in the 60–70 kDa range were more abundant in LOW than in HIGH and WE, indicating that this band contained proteins derived mainly from the seminal vesicles, which produce most of the SP in LOW.