Diatom/copepod interactions in plankton: the indirect chemical defense of unicellular algae

Numerous coexisting species can be observed in the open oceans. This includes the complex community of the plankton, which comprises all free floating organisms in the sea. Traditionally, nutrient limitation, competition, predation, and abiotic factors have been assumed to shape the community structure in this environment. Only in recent years has the idea arisen that chemical signals and chemical defense can influence species interactions in the plankton as well. Key players at the base of the marine food web are diatoms (unicellular algae with silicified cell walls) and their main predators, the herbivorous copepods. It was assumed that diatoms represent a generally good food source for the grazers but recent work indicates that some species use chemical defenses. Secondary metabolites, released by these algae immediately after wounding, are targeted not against the predators themselves but rather at interfering with their reproductive success. This strategy allows diatoms to reduce the grazer population, thereby influencing the marine food web. This review addresses the chemical ecology of the defensive oxylipins formed by diatoms and the question of how these metabolites can act in such a dilute environment. Aspects of biosynthesis, bioassays, and the possible implications of such a chemical defense for the plankton community structure are also discussed.     

调整工艺条件降低脲醛胶生产的操作成本

根据生成脲醛树脂的反应机理和反应特性,对生产周期的控制步骤——缩聚阶段的工艺条件进行调整,采用在不同反应阶段调整不同工艺条件的方法,使整个反应周期由原来的6．0h缩短到5．0h,从而提高设备利用率、降低生产的操作成本,同时因充分利用反应自身放出的热量,可降低生产能耗。     

降低生物柴油生产成本的研究进展

综述了除政策因素外,降低生物柴油生产成本的5种方法:选择含油率高、再生周期短、适应贫瘠土地及不同气候条件的新型植物原料;研究新型固体催化剂;引入新工艺(超临界法和超声波法);使用比较简便的方法将废弃的甘油转化为高附加值的产品(环氧氯丙烷、1,3–丙二醇、丙酮醇等)以及适度生产规模等。     

Methane production from citrus wastes: process development and cost estimation

BACKGROUND: Because of its extreme toxicity for microorganisms, the limonene content of citrus wastes (CWs) has been a major obstacle to the conversion of CWs to biofuels. The main objective of this study was to develop a new process for the utilization of CWs that can be economically feasible when the supply of CW is low. RESULTS: Steam explosion pre‐treatment was applied to improve the anaerobic digestibility of CWs, resulting in a decrease of initial limonene concentration by 94.3%. A methane potential of 0.537 ± 0.001 m³ kg^?1 VS (volatile solids) was obtained during the following batch digestion of treated CWs, corresponding to an increase of 426% compared with that of the untreated samples. Long‐term effects of the treatment were further investigated by a semi‐continuous co‐digestion process. A methane production of 0.555 ± 0.0159 m³ CH₄ kg^?1 VS day^?1 was achieved when treated CWs (corresponding to 30% of the VS load) were co‐digested with municipal solid waste. CONCLUSION: The process developed can easily be applied to an existing biogas plant. The equipment cost for this process is estimated to be one million USD when utilizing 10 000 tons CWs year^?1. 8.4 L limonene and 107.4 m³ methane can be produced per ton of fresh citrus wastes in this manner. Copyright © 2011 Society of Chemical Industry     

Genetic component of variation in chemical defense ofOreina gloriosa (Coleoptera: Chrysomelidae)

Defensive secretions of adultOreina gloriosa, liberated at the surface of the pronotum and elytra, contain a complex mixture of cardenolides, and ethanolamine. Proportions and concentrations of constituents determined by reverse-phase HPLC show considerable variation among individual beetles. Heritabilities of proportions of five main components were estimated by mother-offspring regression providing a validation of the less reliable full-sib correlation estimates. Average heritabilities based on the two methods were 0.51 and 0.58, respectively, estimated by using offspring of two age groups. Regression estimates of 2- and 10-week-old offspring differed significantly for one secretion constituent (RT16). Heritability estimates of concentrations of 16 secretion components were calculated by full-sib correlation analysis. Average heritability was 0.45, indicating a significant genetic component. Estimates did not differ significantly between the two age groups. We also estimated heritabilities of concentrations by a two-way model including data from offspring of both age groups. Heritability estimates based on this model are thought to correspond approximately to estimates based on samples from natural populations. The average of these estimates was lower (h ² =0.31) than the average heritability of each age group separately (h ² =0.45), suggesting a developmental effect on variation in chemical defense ofO. gloriosa.     

Physiological sources of variation in chemical defense ofOreina gloriosa (Coleoptera: Chrysomelidae)

The defensive secretion of the alpine chrysomelidOreina gloriosa is a complex mixture of mainly cardenolides and tyrosine betaine. Individually sampled secretions of adult laboratory-reared and field-collected beetles were analyzed by reverse-phase HPLC; 16 secretion components were quantified. Quantities and concentrations of different components were significantly affected by the age, sex, and reproductive status of individual beetles. Aging was correlated with marked increases (up to 4.4-fold) and decreases (up to 2.7-fold) of quantities and concentrations of several components. Differences between the sexes were smaller, but quantities of all components and concentrations of several components were larger in laboratory-reared females than in males. There was less of one component of the secretion in mated than unmated females, but the concentrations of four secretion components were higher (up to 1.6-fold) in mated females.     

化学混凝法在糊树脂废水处理中的应用

介绍了应用化学混凝法处理糊树脂废水的原理和工艺流程，并从运行成本、处理效果及效益等方面进行实例分析。     

用化学分析法研究三聚氰胺甲醛树脂的结构

三聚氰胺甲醛树脂的结构随反应条件的变化会有较大的差异,深入了解三聚氰胺甲醛树脂的化学结构对树脂的反应终点判断、稳定性以及充分发挥其使用性能具有重要的指导意义.采用了化学方法对3种典型工艺条件下合成的三聚氰胺甲醛树脂中甲醛的结合形式进行了化学基团含量测定,根据合成工艺和实验结果进行了结构分析.     

Energy requirements and production cost of the spray drying process of cheese whey

The influence of spray drying conditions on the energy required, production cost, and physicochemical characteristics of cheese whey was researched. The factors investigated were the inlet air temperature (180–220°C), outlet air temperature (80–100°C), and silica and maltodextrin (DE-10) as additives at 2 and 5% (w/w), respectively. Analysis of variance revealed that the inlet and outlet air temperatures, and the addition of additives had significant effects (p?T_inlet of 180°C, T_outlet of 80°C, and the addition of 5% additive material. Under these conditions, 0.2165?kg/h of dried product was obtained, with a moisture content of 2.08% and water activity of 0.125, and the product cost was $17.06?kg with an energy consumption of 2.0490?kW?·?h/kg of dry product.     

电石法生产PVC树脂的成本分析

介绍了目前国内电石法生产PVC树脂的成本分布情况。我国 1999年PVC的产量为 195万t/a(电石法为 111万t) ,2 0 0 0年PVC产量为 2 45万t/a(电石法为 12 4万t,比 1999年提高了 11.7% ,占总产量的 5 1% )。在用电石为原料生产PVC过程中 ,电石和氯化氢占总成本的 74.8% ,是影响生产成本的主要因素。进一步降低生产成本的措施是 :(1)回收合成气中未反应的氯化氢 ;(2 )改进生产配方 ,使用国产助剂 ;(3)提高电石水解温度 ;(4 )滤液、离心母液复用 ,将塔液密闭集中后用作电石水解 ;(5 )改变干燥的操作条件。改进措施后可节省费用 30 0元 / (t·PVC) ;连同 (6 )把电石消耗定额由 1.6t/ (t·PVC)降至 1.4t/ (t·PVC) ,将使总生产成本下降 70 0元 / (t·PVC)。文中还简述了电石泥综合利用的几种方法     

Evidence for chemical defense in tropical green algaCaulerpa ashmeadii (Caulerpaceae: Chlorophyta): Isolation of new bioactive sesquiterpenoids

Results of field feeding preference studies with 12 species of tropical green algae of the genusCaulerpa showed thatC. ashmeadii was preferred least by herbivorous fishes. Chemical investigations ofC. ashmeadii demonstrated the presence of high concentrations of sesquiterpenoid metabolites. The chemical isolation and structural elucidation of five majorC. ashmeadii metabolites, as well as the results of field feeding preference, antimicrobial, and ichthyotoxicity assays demonstrating the biological activities of these metabolites are reported here.     

Evaluation of capital cost data: Part 9: Liquid waste disposal with emphasis on chemical treatment

Capital cost correlations are given for chemical feed systems, chlorination, ozone disinfection, ultraviolet light disinfection, ion exchange, flocculation, and carbon adsorption. Most of the correlations are accurate to ± 30%, expressed in Canadian dollars and adjusted to a Marshall and Swift value of 1000. Details as to what components are included in the cost are given. Data are given for the labour and material costs to create a working process module. To put the current data into perspective, several hundred sources of cost data were analyzed. The major correlations are compared, on a consistent basis, with current data.     

Minimization of organic chemical load in direct dyes effluent using low cost adsorbents

The work is carried out to minimize the organic chemical load (unexhausted dye contents) in direct dyes effluent using low cost adsorbents. The studies are made with different direct dyes, i.e. Direct Red 28, Direct Yellow 12, Direct Orange 26 and Direct Blue 1 with various adsorbents. Three different bio/natural materials have been selected as adsorbents. These includes, Sugarcane bagasse pith (SB), Saw dust (SD)—the plant origin products, and Brick powder (BP)—a silica based material obtained from earth's crust on thermal heating. These substances are almost discarded waste products with the possibility of use as adsorbents. Experimental work for the dye removal from the effluent by activated charcoal (AC) has also been carried out and the results are compared with other adsorbents. The amount of unexhausted organic dye present in the effluent is measured as chemical oxygen demand (COD) before and after the treatment. Adsorbent Sugarcane bagasse pith shows good performance as compared to Saw dust and Brick powder. For understanding the behaviour of adsorbents Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) has also been carried out.     

电石法PVC企业的成本分析和发展思路

分析了国内电石法PVC企业的生产成本情况,指出了影响成本的主要因素,并提出了发展思路。     

优化配煤结构降低成本的经验

为适应高炉大型化对焦炭质量提出的更高要求,通过开展煤岩分析、优化配煤结构、加大省内主焦煤用量、应用低质低价煤资源、开发利用非炼焦煤资源等措施,稳定了焦炭质量,降低了配煤成本,实现了资源的充分利用。     

Soldier frontal glands of the termiteMacrotermes subhyalinus: Morphology,chemical composition,and use in defense

Soldiers of the East African fungus-growing termiteMacrotermes subhyalinus (Rambur) (Termitidae: Macrotermitinae) employ both mechanical and chemical defenses. Soldiers release a chemical secretion composed of long-chain saturated and monounsaturated hydrocarbons into wounds inflicted by their powerful mandibles. Chemical analysis of the secretion shows the paraffin fraction to consist primarily ofn-tricosane,n-pentacosane, 3- and 5-methylpentacosane, and 5-methylheptacosane. The major oleflns were identified as (Z)-9-heptacosene and (Z)-9-nonacosene. The secretion originates from the frontal glands of both major and minor soldiers; however, the hypertrophied gland of the major soldiers contains 500-fold more secretion than that of the minor soldiers. This secretion appears to impair the healing of wounds in test ants, and thus could represent a valuable supplement to the mechanical defense mechanism.     

电石法生产PVC树脂的成本分析与控制

介绍了石河子中发公司采用电石法生产PVC树脂的成本分析及采取的措施：（1）加强电石采购管理,次品电石使用量降至20%以下,使电石单耗降低;（2）氯化氢纯度控制应大于93%;（3）适当扩大生产能力（由8kgt/a增至2.5万t/a）。改进后生产成本由5419元/t下降至3955元/t。     

高铁酸盐制备影响因素研究和中试生产装置的开发

为了开发和优化高铁酸盐中试生产装置,通过小试试验对隔膜材料和生产工艺等进行了研究,结果表明,孔径小于5μm的聚偏氟乙烯膜使用寿命较长;母液循环利用提高了药剂利用率、降低制备成本;电解液NaOH不宜饱和,浓度应降低到14～ 16 mol/L; BaFeO4提取率显著高于K2FeO4,低温（5℃）、隔绝空气密封下,保存30 d以上纯度仍在50％左右.根据小试结果,开发了高铁酸盐中试生产装置,产量可达20 g/h以上,生产总成本约为6万元/t.     

清洁技术是推动化学工业清洁生产的关键

清洁生产是实现经济环境协调发展的战略。本文从化工原料、化学反应、反应介质和化工产品等几个方面,介绍了实现清洁生产的途径,指出清洁技术或绿色工艺是促进化工清洁生产的关键,也是化学工业今后的发展方向。     

Interactions betweenAlloxysta brevis (Hymenoptera,Cynipoidea, Alloxystidae) and honeydew-collecting ants: How an aphid hyperparasitoid overcomes ant aggression by chemical defense

Foraging females of the aphid hyperparasitoidAlloxysta brevis were attacked by honeydew-collecting workers of the antLasius niger at the first encounter. However, ants abandoned their attacks quickly, and foragingA. brevis remained unmolested for a subsequent time interval of approximately 5 min, which is long enough for the hyperparasitoid to oviposit successfully. Furthermore, freshly killed intactA. brevis were disregarded by ants, while decapitated specimens were readily removed. We present evidence thatA. brevis females release a mandibular gland secretion, which contains 6-methyl-5-hepten-2-one, actinidin, and unidentified iridoids, in response to an ant attack. This secretion functions both as a measure of self-defense if the female is seized by an ant worker and as a repellent, which prevents ant attacks during subsequent encounters. This is the first evidence for chemical defense in a hymenopterous parasitoid. It enablesA. brevis females to hyperparasitize ant-attended aphids that constitute a major proportion of their hosts and significantly reduces mortality by ectohyperparasitoids.