Color characteristics of Cu-Zn-Al alloys

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Olfactory Responses of Banana Weevil Predators to Volatiles from Banana Pseudostem Tissue and Synthetic Pheromone

As a response to attack by herbivores, plants can emit a variety of volatile substances that attract natural enemies of these insect pests. Predators of the banana weevil, Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae) such as Dactylosternum abdominale (Coleoptera: Hydrophilidae) and Pheidole megacephala (Hymenoptera: Formicidae), are normally found in association with weevil-infested rotten pseudostems and harvested stumps. We investigated whether these predators are attracted to such environments in response to volatiles produced by the host plant, by the weevil, or by the weevil–plant complex. We evaluated predator responses towards volatiles from banana pseudostem tissue (synomones) and the synthetic banana weevil aggregation pheromone Cosmolure+ in a two-choice olfactometer. The beetle D. abdominale was attracted to fermenting banana pseudostem tissue and Cosmolure+, whereas the ant P. megacephala was attracted only to fermented pseudostem tissue. Both predators were attracted to banana pseudostem tissue that had been damaged by weevil larvae irrespective of weevil presence. Adding pheromone did not enhance predator response to volatiles from pseudostem tissue fed on by weevils. The numbers of both predators recovered with pseudostem traps in the field from banana mats with a pheromone trap were similar to those in pseudostem traps at different distance ranges from the pheromone. Our study shows that the generalist predators D. abdominale and P. megacephala use volatiles from fermented banana pseudostem tissue as the major chemical cue when searching for prey.     

连续铸造时铝合金的结晶方式和显微组织

由于枝晶网尺寸或枝晶间距同局部凝固时间之间有确定的关系,所以则有可能根据铸态显微组织计算凝固热参数。在不同类型的铝锭(各种直径的直接水冷铸锭,普通模和电磁模铸造的铸锭,辊式、带式及板式铸造机铸出的带板以及Properzi法铸造的棒,横断面上测量枝晶间距,以此作为计算的基础。根据测量结果,本文定性地讨论了铝锭凝固过程中的结晶热参数以及铸造条件对结晶热参数的影响。     

手机短信也骗人

某日,我在教室里坐着,我一同学把他手机放到我面前,让我看一个短信,我看了一下内容,大惊,说有个人通过代理商给他充了1000元活费,我当时就无语了,我说“谁充错了吧？”随即看到了他阴险的笑容,有假,于是我问他怎么弄的,他不说,于是在我紧急采购来的零食的诱惑下,他招了,是一个叫短信骗子的软件做的,告诉我用来骗人不错。     

从外到里教你快速辨别翻新笔记本电脑

对于国人而言,购买一款自己喜爱的笔记本电脑（注：以下简称本本）不容易．往往需要存上一两个月的工资才能搞定。因此,谁都不希望买到质量差,甚至是别人用过的二手货或者翻新机。别不信,电脑城里的伙计最喜欢把用来给顾客展示的本本样机高价兜售给用户,很多用户就这样糊里糊涂地把二手本本抱回了家。     

Work routinization and implications for ergonomic exposure assessment

Jobs in many modern settings, including manufacturing, service, agriculture and construction, are variable in their content and timing. This prompts the need for exposure assessment methods that do not assume regular work cycles. A scheme is presented for classifying levels of routinization to inform development of an appropriate exposure assessment strategy for a given occupational setting. Five levels of routinization have been defined based on the tasks of which the job is composed: 1) a single scheduled task with a regular work cycle; 2) multiple cyclical tasks; 3) a mix of cyclical and non-cyclical tasks; 4) one non-cyclical task; 5) multiple non-cyclical tasks. This classification, based primarily on job observation, is illustrated through data from a study of automobile manufacturing workers (n = 1200), from which self-assessed exposures to physical and psychosocial stressors were also obtained. In this cohort, decision latitude was greater with higher routinization level (p < 0.0001), and the least routinized jobs showed the lowest self-reported exposure to physical ergonomic stressors. The job analysis checklist developed for non-routinized jobs is presented, and limitations of the task analysis method utilized in the study are discussed. A work sampling approach to job analysis is recommended as the most efficient way to obtain a comparable unbiased exposure estimate across all routinization levels.     

Characterization of posture and comfort in laptop users in non-desk settings

Laptop computers may be used in a variety of postures not coupled to the office workstation. Using passive motion analysis, this study examined mean joint angles during a short typing/editing task in college students (n=20), in up to seven positions. Comfort was assessed after task execution through a body map. For three required postures, joint angles in a prone posture were different than those while seated at a couch with feet either on floor or on ottoman. Specifically, the prone posture was characterized by comparatively non-neutral shoulders, elbows and wrists, and pronounced neck extension. Significantly greater intensity and more regions of discomfort were marked for the prone posture than for the seated postures. It is recommended that the prone posture only be assumed briefly during laptop use. Exposure to laptops outside of the office setting should be assessed in future epidemiologic studies of musculoskeletal complaints and computer use.     

DELIBERATlON TO THE DEFINITION OF TOOTH THICKNESS FOR INVOLUTE HELICAL GEAR IN INTERNATIONAL STANDARD ISO1122／1

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刻就刻出“特别精彩”—刻录光盘玩花样

想刻录一张能够启动系统、分区、格式化,让重装系统变得简单的自启动光盘吗?想刻录“自动还原系统光盘”,让系统恢复完全自动化、傻瓜化、一条龙吗?想让制作的光盘放入光驱后会自动打开Winamp播放音乐吗?……使用它们,可以给使用电脑带来无穷的便利与乐趣。实话告诉你,不难的！