Corrections and clarifications

The Random Samples item "The mosquito and the marigold" (12 May, p. 809) incorrectly suggested that a team of scientists in India first characterized phototoxins in marigolds that kill mosquito larvae. In fact, they were originally discovered in the early 1980s in Canada by investigators at the University of British Columbia [see J. T. Arnason, B. J. R. PhilogAne, P. Morand, K. Imrie, B. Hasspieler, A. E. R. Downe, "Naturally occurring and synthetic thiophenes as insecticides," American Chemical Society Symposium Series 387, 164 (1989)].     

Geologists Get Together to Dissect Earth's Thin Skin

At the annual meeting of the Geological Society of America in Boston during late October, Earth's crust came in for close scrutiny. One surprise was its age: Chemical and isotopic evidence suggested the crust formed soon after the planet did. Participants also discussed features of today's crust, including a horizontal slice beneath San Francisco and the possibility that a particular kind of crustal stretching, long envisioned, may not actually take place.     

Powering the nanoworld

Devens Gust, a chemist at Arizona State University in Tempe, and a handful of colleagues have built tiny refineries that convert the energy in sunlight to chemical fuel to power nanomachines. The fuel in this case is adenosine triphosphate, the same energy-rich molecule that powers chemical reactions inside cells. At last August's meeting of the American Chemical Society in Washington, D.C., Gust reported that he and his colleagues had collaborated with other groups to run their protein-based molecular machines on little more than sunlight.     

Chemistry community swarms into windy city

Two times each year, legions of chemists gather in North America for a massive meeting to discuss the state of the art in their science. The second of this year's get-togethers occurred 2 weeks ago, when the 206th national meeting of the American Chemical Society (ACS) drew about 13,000 chemists, scientists, and onlookers to Chicago. Researchers shared 4800 or so papers and posters on everything from making waste plastic into fuel oil to the chemical basis for the stench of ginkgo fruit to modeling the first instants of photosynthesis.     

化控种衣剂对大豆籽粒灌浆过程及产量形成的影响

以垦农4号为材料,研究了化控种衣剂和常规种衣剂对大豆籽粒灌浆过程和产量形成的调控,探讨了内源激素作用的生理机制。结果表明,大豆应用化控种衣剂可以提高生育后期叶源和根源的生理活性;内源激素含量的变化利于籽粒内容物的充实和产量的形成;应用化控种衣剂平均比常规种衣剂增产13.9%。     

Chemical methylation of inorganic mercury with methylcobalamin, a vitamin B12 analog

Chemical methylation of mercuric chloride with methylcobalamin has been studied. Methylated mercury was detected by gas chromatography; and analysis of the products of the reaction by thin-layer chromatography revealed that the methylation proceeded at a remarkably high rate when methylcobalamin and inorganic mercury were mixed. Dimethylmercury was an initial product of the reaction.     

A glycolipid antigen associated with Burkitt lymphoma defined by a monoclonal antibody

The antigen defined by a rat monoclonal antibody directed to a Burkitt lymphoma cell line was identified as globotriaosylceramide [Gal alpha (1 leads to 4)-Gal beta (1 leads to 4)-Glc beta (1 leads to 1)-ceramide]. The antibody demonstrated a strict steric specificity since it did not react with globoisotriaosylceramide [Gal alpha (1 leads to 3)-Gal beta (1 leads to 4)-Glc beta (1 leads to 1)-ceramide], the positional isomer of the antigen associated with the Burkitt lymphoma. Chemical analysis of various Burkitt lymphoma cell lines revealed that the Burkitt lymphoma cells contained more than 100 times as much of the glycolipid antigen as was found in other human lymphoma and leukemia cell lines.     

混凝法对松香厂废水处理的研究

本文论述了采用无机絮凝剂、有机絮凝剂及合成聚合物对福建南平林化厂松香车间废水进行了处理研究,取得了大量实验数据。结果表明,电解质处理松香厂废水,具有较好的效果。该研究为了我国松香厂废水处理提供了数据和经验。     

3种新型化学杂交剂诱导小麦雄性不育效果比较

以杂种小麦新品种西杂一号和 1 6个小麦常规品种为供试材料 ,应用混合线形模型研究了 3种化学杂交剂 SQ- 1 ,GENESIS和 BAU94 0 3诱导小麦雄性不育的效果及对种子性状的影响。结果表明 ,SQ- 1在 3种化学杂交剂中的杀雄效果最好 ,并对杂交种种子的千粒重有提高作用 ;GENESIS和 BAU94 0 3不同程度对杂交种种子千粒重有降低作用 ,其中 BAU94 0 3影响更大 ;SQ- 1和 GENESIS对杂交种发芽率、发芽势和容重的影响与对照不喷药无显著差异 ,但 BAU94 0 3与对照有显著差异     

Organic matter in a coal ball: peat or coal?

Chemical analyses of morphologically preserved organic matter in a Carboniferous coal ball reveal that the material is coalified to a rank approximately equal to that of the surrounding coal. Hence, the plant tissues in the coal ball were chemically altered by coalification processes and were not preserved as peat.     

Short-lived chemical heterogeneities in the archean mantle with implications for mantle convection

The neodymium isotope and samarium-neodymium systematics of 2.7-billion-year-old mantle-derived magmas indicate that the lifetime of chemical heterogeneities was much shorter in the Archean mantle than in the modern mantle. Isotopic evidence is compatible with a Rayleigh number 100 times larger and convection 10 times faster in the Late Archean compared with the present-day mantle. Modern plate tectonics thus may be an improbable analog for the Archean. Chemical heterogeneities in the mantle may originate upon magma migration and mineralogical phase changes rather than by recycling of oceanic and continental crust.     

诱导剂对杨树细菌溃疡病寄主体内过氧化物酶活性的影响

选用５种化学诱导剂和４种生物诱导剂分别试验分析了其对杨树苗木体内过氧化物酶活性的影响。试验结果表明：ＳＡ、ＬＭＳ、ＰＭＡ化学试剂和Ａ、Ｂ、Ｃ、Ｄ生物试剂都能有效地提高杨苗体内所氧化物酶活性。ＹＱ、ＹＬ提高过氧化物酶活性的能力较弱。     

芒萁乙醇提取物中化学成分的薄层层析分析

研究芒萁乙醇提取液中的化学成分。采用超声辅助溶剂提取和分步萃取法对新鲜芒萁的化学成分进行提取和初步分离,采用薄层层析法对各个组分进行分析。提取物萃取分离以后,水相和水饱和正丁醇相的组分较多,石油醚相次之,乙酸乙酯相为最少;薄层层析检测中,展开剂氯仿∶甲醇为7∶3（V/V）的展开效果较好。     

国内农化上市公司盈利能力不强成长能力较弱——2009年农药、化肥上市公司主营业务利润率、主营业务收入增长率排行

目前12家农药上市公司主营业务利润率超过20%的只有3家,分别为:诺普信、利尔化学、扬农化工,仅占25%;主营业务增长率超过10%的仅有诺普信一家,占8%。22家化肥上市公司主营业务利润率超过20%的仅有5家,分别为:盐湖钾肥、赤天化、辽通化工、兴化股份、湖南海利,占23%;主营业务增长率超过10%的也只有5家,分别为:建峰化工、天润发展、湖北宜化、华鲁恒升、盐湖钾肥。     

不同栽培密度下玉米化学调控效果的研究

[目的]研究不同栽培密度下玉米化学调控的效果。[方法]以玉米杂交种浚单20和中农大4号为材料,分别研究了在华北、东北地区不同栽培密度下化学调控对玉米产量及产量构成因子和玉米株型的影响。[结果]＂玉黄金＂可调控玉米株型,使玉米个体的株高、穗位降低,使穗下部节间粗壮,使玉米的抗倒伏能力增强。化控处理辅助栽培可提高玉米的最适栽培密度,较传统栽培条件下提高了0.75万株/hm2左右。[结论]为玉米的高产栽培提供了理论依据。     

Scientific Meetings

In the issue of 16 Sept., page 526, the American Mathematical Society which will hold its 62nd annual meeting in Houston, Tex., on 27-29 Dec. was incorrectly listed as the American Meteorological Society.     

Microbiology. Fighting bacterial fire with bacterial fire

Work presented last week at the annual meeting of the American Society for Cell Biology in San Francisco suggests that applying a harmless bacterium or its products to surgical wounds may thwart infections by the dangerous pathogen Staphylococcus aureus, a major cause of hospital-acquired infections. Although physicians have previously pitted one bacterium against another to prevent infections of the intestinal and genitourinary tracts, this is the first attempt to use a friendly microbe to prevent infection of surgical wounds, say experts. The findings also point to a possible mechanism for this "bacterial interference." They suggest that a protein secreted by the harmless bacterium prevents the pathogen from getting a foothold in injured tissue.     

Chemical species in fly ash from coal-burning power plants

Fly ash specimens from four power plants in the Tennessee Valley Authority system have been separated into three matrices: glass, mullite-quartz, and magnetic spinel. Chemical species of trace elements are defined to a large extent by the matrices that contain them. The magnetic component of fly ash is ferrite. The mullite-quartz phase is relatively pure and can be recovered as a resource.