A non-destructive single plate method for measurement of thermal resistance of polymer sheets and fabrics

Measurement of thermal resistance of polymer sheets and fibrous layers is important in various applications including those within the engineering, ergonomics, clothing design and personal protective equipment fields. Standard methods for measurement of thermal resistance of plain materials are generally time consuming, expensive and often require the sample to be cut. Moreover, the temperature difference between the surfaces of both plates surrounding the sample must be known, as well as the sample thickness. This article describes a new measuring device named the Thermoscope. The Thermoscope is not limited by the aforementioned requirements and is able to evaluate the thermal resistance of polymer sheets and textiles by touching the sample on one surface alone. Simultaneously, the other surface is kept in thermal contact with the supporting base. The accuracy of this device was compared with the Alambeta thermal insulation tester. Effects of various base materials on measurement precision were also studied.     

生物技术在欧美遇到的抵制及教训

回顾了欧美公众对生物技术的种种疑虑和生物技术的研究开发所遇到的阻力，分析了产生这种现象的原因，并提出了我国应从中吸取的教训。     

Clogging of Filtering Material Systems Used for Disposable Respirators

The article shows the problem of clogging in connection with the parameters of filtering materials used in respiratory protective equipment. The results of investigations of airflow resistance changes during the depositing of dust inside the filtering material are presented. The configuration of layers differing in mass per unit area and the number of layers, were taken into consideration. For each configuration, the clogging abilities and the changes of airflow resistance as a reason of loading with dust were assessed. The analysis of tested materials confirms the hypothesis that there is an important coincidence between the properties of the material used in filtering equipment and the clogging coefficient. The results show that the filter should have a layered structure and that the outer layer should be made of a nonwoven of relatively high surface density.     

A Contribution to the Study of the Antidust Respirators’ Real Performance

In most industrial enterprises, hazardous factors are present in quantities exceeding permissible levels. Such a situation requires using antidust respiratory protection. It has been suggested, however, that filters for respirators are not assessed properly and that lab results might not be related to real filtering efficiency in industry. This article contains test results of some commercially available filtering half-masks, including the effect of loading with real dust, high humidity, high temperature, and a combination of loading with dust and high humidity on the half-masks’ performance. The results show that the effect of these factors is considerable and that a combination of loading with silica dust and exposing to high humidity can cause a complete loss of performance.     

湿度显示卡在防水试验中的应用

文章介绍了采用湿度显示卡在产品防水试验中的应用。结合IP等级中的防水试验,通过分析产品的防水结构与内部主要安全部件,科学使用与排布湿度显示卡,准确判定进水路径,以此达到对防水试验结果的准确判定与分析。     

常用过滤材料对微细颗粒过滤性能的研究

通过实验手段对几种过滤材料的阻力、过滤效率进行了研究。结果表明,目前常用的过滤材料对超细颗粒物的除尘效果并不理想,尚有很大的提升空间。     

Transepithelial transport and cellular accumulation of steroid hormones and polychlorobiphenyl in porcine kidney cells expressed with human P-glycoprotein

Endocrine disrupters such as sex hormone-like chemicals and the non-physiological ligands for aryl hydrocarbon receptor (AhR) exert many adverse biological effects. The ligands for AhR disturb gene expression downstream of the gene induced by estrogen receptor at a very low concentration. Thus, transepithelial transport and cellular accumulation of cortisol (COR) and estrogen as congeners of sex hormone-like chemicals, and 3,3^′,4,4^′-tetrachlorobiphenyl (TeCB) as one of the ligands for AhR were examined in a monolayer of porcine kidney cells transfected with human P-glycoprotein (LLC-COL). The net basal-to-apical transport of COR increased in LLC-COL compared to that in the wild type cells (LLC-PK1) the same as in vinblastine, whereas the net transport of estradiol (EST) was not detected in either cell group. Though the diffusion transports of EST for both directions, basal-to-apical and apical-to-basal, were higher than that of COR, cellular accumulation of EST was higher than that of COR. Transepithelial transport of TeCB was very low and the net basal-to-apical transport was not detected, while it was highly accumulated in the epithelial cells. The accumulation was slightly higher in LLC-COL than in LLC-PK1 at high dose.     

New findings regarding the significance of pavement skid resistance for road safety on Swiss freeways

INTRODUCTION: The significance of the influence of poor pavement skid resistance values on accident frequency in wet pavement conditions has been the object of many studies over several years. The various investigations have produced very diverse findings. Only seldom, however, has detailed consideration been given to the central question of whether pavement skid resistance is a decisive parameter in the occurrence of local accident "black spots." Until now, the focus has been more on describing a relationship between pavement skid resistance and accident frequency. METHOD AND RESULTS: In the course of the network-wide survey of the states of pavements and of accident occurrence on Switzerland's freeways from 1999 to 2003, it emerged that a relationship with inadequate pavement skid resistance was provable for only a small proportion of accident black spots. These findings were used to frame a guideline for authorities and highway operators about how to treat skid resistance when assessing pavements and accident occurrence on freeways.     

Induced responses to herbivory in the Neotropical ant-plant association between Azteca ants and Cecropia trees: response of ants to potential inducing cues

Plant defense against herbivores often involves constitutive and inducible mechanisms of resistance. Obligate ant-plants, which provide food and housing for ants, are thought to primarily rely on ants for defense against herbivores. This form of plant defense has largely been viewed as static. We have been investigating the dynamic nature of Azteca ants as an inducible defense of Cecropia trees. Ants rapidly recruit to and patrol sites of foliar damage. We propose that Azteca ants can be viewed as an inducible defense for Cecropia trees because of their sensitivity to cues associated with herbivory, their rapid and aggressive recruiting ability, and their reclaimable and redeployable nature as a plant defense. In this study, we examine ant behavior following plant damage, and the potential cues that indude ant recruitment. We found that ants present on leaves when the plant is damaged leave the damaged leaf and recruit other ants to it, presumably by laying recruitment trails. Volatile leaf cues associated with herbivory were important in eliciting an induced response in two experiments. However, we found that cues associated with a congeneric plant elicited a much stronger ant response than conspecific cues. Although the type of leaf damage (gaping wounds versus leaf edge wounds) did not affect the level of ant recruitment, the extent of damage did. Leaves with one hole punched showed a 50% increase in ants, while leaves with five holes punched in them elicited a 100% increase in ant numbers. In sum, it appears that multiple plant-related cues associated with herbivory are involved in induction of ant recruitment in the Cecropia-Azteca system. We discuss the generality of ant responses to herbivory in obligate ant-plant systems, and in facultative ant-plant associations, which may be more common. Received: 23 March 1998 / Accepted after revision: 5 July 1998