Activated coagulation times of normal cows

The Activated Coagulation Time (ACT) was determined on 10 normal cows. Duplicate samples were taken from each cow. The mean ACT was 145 seconds with a range of 120-180 seconds. Standard deviations were 18 and 13 for the first and second sampling, respectively. Repeatability of the ACT was acceptable.     

小麦丛矮病研究之三:灰飞虱同发病的关系

1976—1977年河北晋县贺家寨大队小麦春季灰飞虱的传带病毒率为31—52%,不同地块同代灰飞虱的带毒率异差较大:而秋苗期则为12—35.4%,其中不同地块上同代(四代成虫)灰飞虱的带毒率的差异从33.3%至35.4%则不太大。灰飞虱的有效传毒指数(即虫口数×自然带毒率)同田间小麦发病率的相关性是非常显著的,其r=0.9769。1975—1976两年调查及计算分析结果,其直线回归公式如y=4.12x-2.577。在有效传毒指数0.7—20.9之间用于予测发病率有效。人工分期侵染试验证明小麦在生长发育过程中受侵愈早,病情愈重,其中死株率也愈大。秋季侵染的死株率达95.6%,病指为99.6;夏季侵染的死株率为0,病指为57.6。秋季小麦出苗前后的大量虫口形成小麦10月中下旬的一个发病高峰,第二年春季4月中旬的虫口高峰形成5月上旬的一个发病高峰。3月下旬的一个发病高峰是越冬前受侵的。病毒在小麦植株中的潜育期的长短随小麦的生长速度而异。温度不过其中因素之一,最短5—8天,最长30—40天。侵染后如小麦进入越冬期,即不表现症状,一直要到返青以后。介体灰飞虱在河北晋县以第五代3—4龄若虫在冬麦地及草荒中越冬。夏季在玉米上可以产卵并孵化,但不能长期存活,主要在地头沟边及夏作物荫蔽下的禾草上越夏。冬麦治虫防病的重点应在秋季麦苗出土前,春季则应在3月中旬左右。冬麦适当推迟播种有利于减少发病率。棉间作麦比平作的病情重六倍而粮麦间作的病情比平作的重九倍。     

利用磷肥厂副产氟硅酸防治小麦锈病的研究

作者于1966半报告了氟硅酸对小麦条锈病具有良好药效,氰硅酸是磷肥厂副产,资源丰富、成本低廉。1971年又用氟硅酸与尿素制成便于运输和贮存的晶态的氟硅脲,其分子式为[(NH_2)_2CO]_4·H_2SiF_6。十多年来经过15个省市的田间试验,肯定了氟硅酸和氟硅脲对小麦三种锈病均有效。在山东烟台地区和四川内江地区的大面积推广试用均取得良好效果。防治有效浓度按H_2SiF_6计为0.05～0.10%,药液中须加入湿润剂。除扬花期不可喷药外,其它生育期均可喷药。对小麦的增产效果显著。小麦种子中未发现氟的反常残留。经卫生部门测定,十个样本中有6个氟残留量为0.71～1.98ppm,有1个样本中为3.47ppm,系过量喷药所致。其余3个样本中未检出氟。本文讨论了使用无机氟剂的环境保护问题。根据地球化学和环境化学的最近研究成果,在本文所建议采取的使用浓度下,用氟硅酸防治小麦锈病并无引起环境污染之虞。     

棉铃虫田间分布型及在实践中的应用——2.棉铃虫田间卵量调查及序贯抽样检定防治标准的方法

在调查分析了解棉铃虫卵在田间呈核心理论分布型的基础上,研究了卵量调查方法的改进,应用序贯抽样检定防治标准,及统计资料的代换方法。根据棉铃虫卵在田间呈核心分布型,为了提高田间调查准确度,改进我国已经应用的田间取样方式,提出田间卵量调查方法是:以200株为取样量,采用平行线式,40个样点,每点单行五株。因为这样增多了样点和卵分布核心相遇的机会,经与原采用的单对角线式,双对角线式,棋盘式,分行式取样比较,平行线式取样准确度最高,降低了样本平均数代表性误差。为了节省田间卵量检查时间,可采用调查着卵株率计算百株卵量的办法,或对不同卵量密度的田块区别对待,百株卵量10粒以上检查100株,10粒以下检查200株。以田间百株卵量15粒或着卵株率11.77%为达到防治标准;卵量10粒或着卵株率8.36%为未达到防治标准,制定了序贯抽样检定防治标准的方法。检查卵量序贯抽样确定防治标准的方程:d_o=0.1127n-8.5353d_1=0.1127n 8.5353检查着卵株序贯抽样确定防治标准的方程:d_o=0.0998n-6.4228d_1=0.0998n 6.4228为了使用方便,制定了每次检查五株为单位的序贯抽样确定防治标准的田间实用检定表。实例计算表明,对棉铃虫卵和田间调查资料,进行变量分析,用对数和平方根代换均可。根据卵呈核心或嵌纹分布的特点,对数代换更为合理些。     

A method to test wheat leaves for their reactions to inoculation with Septoria species

The construction and application is described of a polystyrol humidity box in which wheat leaves, while continuing to function as parts of living plants, can be tested for their reactions toSeptoria spp. in an atmosphere nearly saturated with water, as is required for successful infection. The method is simple, accurate ans inexpensive.Samenvatting Voor dit doel is een z.g. vochtdoos geconstrueerd (Fig. 1A). Het te toetsen blad wordt daar doorheen geleid en in de doos geïnoculeerd met een druppel conidiën-suspensie van de schimmel. Onder het blad staat wat water in de doos (Fig. 1B). Na afsluiting ontstaat in de doos de hoge luchtvochtigheid van bijna 100% die nodig is voor de infectie. Dit wordt op deze wijze eenvoudig en goedkoop gerealiseerd. De bladeren die zo worden getoetst blijven onbeschadigd functioneren aan de plant. Na enkele dagen kan de doos worden geopend en kan de symptoom-ontwikkeling worden afgewacht en gevolgd (Fig. 3A, 3B en 4). De methode leent zich voor nauwkeurig werk en vereist zeer weinig infectiemateriaal. De Technische en Fysische Dienst voor de Landbouw (TFDL), Wageningen, ontwierp en construeerde een statief voor het gebruik van de vochtdozen in serie (Fig. 2).     

Sources of parathion exposures for Israeli aerial spray workers, 1977

Exposure of Israeli agricultural spray pilots and ground crews to parathion was studied. Measurements were made with personal samplers contianing wet midget impingers; samples were analyzed by gas chromatography. Cockpit air exposure levels during 11-21-minute sampling periods for 12 flights ranged from nearly 0 to 430 microgram/m3. During sampling periods of 30 minutes to 4 hours the threshold limit value (TLV) of 100 microgram/m3 was exceeded in 2 of 19 instances. In seven measurements of ground crew exposures, TLV was not exceeded. Air washing with parathion resulted in airborne contamination of the ground level area at more than three times the TLV. Skin exposure data suggested that this route of exposure was significant for ground crew workers but not for pilots. Calculations based on the present data and standard absorption formula suggested that total daily intake for ground crew, but not for pilots, exceeded the Accepted Daily Intake (ADI) of 5 microgram/kg body weight. Sources of exposure and contamination for ground crew and pilots were identified. Recommended environmental control measures for parathion exposure should include cockpit air filtration, modification in flight patterns, paving landing areas, installation of hosing and drainage, NaOH neutralization point, and separate loading and unloading sites. Personal control measures were suggested as a supplement.     

苹毒蛾核多角体病毒观察初报

苹毒蛾病毒是典型的核型多角体病毒结构,对苹毒蛾幼虫有较强的致死能力,对于开展苹毒蛾的生物防治有一定意义;在病毒分类上根据形态鉴别,可能属于杆状病毒属(Baculovirus)亚组(A)的一个种。     

Semiconductor alternating-current motor drives and energy conservation

The concentration of electrical energy usage in alternating-current motor drives presents an opportunity for substantial conservation. Emerging advances in power semiconductor transistor systems will support a major commerical effort to this end. An alternating-current synthesizer for this purpose may soon be available. The synthesizer produces electricial power of variable and programmable frequency, voltage, and wave form so that performance can be optimized. This technology provides the additional opportunity for fundamental improvements in electrical distribution and usage systems in the longer term. Power processing with semiconductor a-c motor controls is expected to become widespread in the near future.     

Nitrogen-fixing anabaena: physiological adaptations instrumental in maintaining surface blooms

Both laboratory and in situ studies indicate that the nitrogen-fixing blue-green nuisance algae Anabaena spp. have developed adaptive means of dominating surface lake waters. During the dramatic diurnal shifts in surface light intensity and oxygen saturation accompanying blooms, Anabaena can overcome oxygen toxicity by sequential optimization of carbon dioxide and nitrogen fixation and by pigment alteration. These mechanisms allow optimal utilization of the radiant energy while minimizing competition for photoreductant between two main energy-demanding processes.