黄铁矿对二水物法制湿法磷酸的影响

针对湖南洗溪磷矿重介质选精矿含黄铁矿较多这一情况，研究了黄铁矿对该矿采用二水物法制湿法磷酸的影响，阐明了用重介质选精矿制湿法磷酸能获得较好经济技术指标的原因，提出了合理评价重介质选精矿质量的建议。     

有机附聚剂用于砂金矿选别的研究

文章介绍了用有机附聚剂选别砂金矿的实验研究，详细叙述了附聚剂的选别原理及各组份的性能和作用。实验结果，人工配料选金的回收率可达９０％。稳定性和重现性都较好。附聚剂无毒，无害，配制容易，价廉，为工业型实验提供了依据。     

软化水用于铁矿石浮选的研究

详尺的论述了几种脂肪酸类捕收剂在软，硬水质中的选别效果，提出了选厂技术改造的方向。     

黄铁矿对二水物法制湿法磷酸的影响

针对湖南洗溪磷矿重介质选精矿含黄铁矿较多这一情况，研究了黄铁矿对该矿采用二水物法制湿法磷酸的影响，阐明了用重介质选精矿制湿法磷酸能获得较好经济技术指标的原因，提出了合理评价重介质选精矿质量的建议。     

几种选粉机的技术性能和经济效益分析

水泥工业常用的三种空气动态选粉设备，选粉机理一样，而效果相差很大，离心式选粉效率最低，涡流式选粉效率最高，经济效益显著，投资虽多，但资金回收快。本文将其技术性能及经济效益，有重点地加以分析比较，说明涡流选粉机是具有高效率、高效益的选粉设备。     

高效选粉机的构造及工作原理（一）

高效选粉机的构造及工作原理（一）江旭昌天津水泥工业设计院为了克服第一、二代选粉机存在的缺点，提高选粉效率和选粉精度，进而提高粉磨效率，日本小野田（ＯＮＯＤＡ）公司率先研制开发了Ｏ－Ｓｅｐａ型高效选粉机，在选粉原理上是个重大突破。由于Ｏ－Ｓｅｐａ高效选...     

国内选净最新技术——干式选净理论和实践初探

选净与选别不同，选净主要要求物料颗粒表面的洁净。本文旨在探索干式选净设备的设计、制造的理论和实践问题。尽管设计已在实践中获得成功，理论依据已得到工业试验的印证，但是由于干式选净技术目前在国内尚属新技术，还有待于进一步开展研究工作。     

选教制之我见

本文叙述了选教制产生的背景、现状及对提高教学质量的现实意义，分析了实施选教制面临的困难和问题，并据此提出了一系列改革措施。     

选粉机的改造

我公司以前用的是早期的旋风式选粉机，选粉效率低，最好仅能达到65%，限制了粉磨系统的生产能力，为此，我们根据新一代选粉分级理论，结合我公司的具体情况，对旋风式选粉机进行了改造。     

预富集技术研究进展

预富集技术主要是根据矿石矿物与脉石矿物在某种特性上的差异，利用光电选、重选、磁选、浮选及化学选等工艺提高矿石矿物入选品位，预先抛弃部分脉石矿物，从而为后续分选作业创造有利条件。概述了预富集技术的研究现状，从光电选、重选、磁选、浮选、化学选以及联合工艺等方面介绍了预富集技术在选矿领域的研究及应用，分析了各种预富集技术的优缺点，并指出采用联合工艺进行预富集是实现低贫矿石和废石资源综合利用的重要技术手段。     

Olfactory-based behavioral interactions among five species in the southern pine bark beetle group

Olfactory-mediated behavioral interactions were investigated among the five scolytid species comprising the southern pine bark beetle group. Behavioral response, as determined from field trap catch data, showed that each species was attracted in greatest numbers to the pheromonal blend produced by conspecifies. Interspecifically,D. frontalis displayed no cross-attractancy toIps pheromonal blends, but was weakly attracted to the pheromonal blend of femaleD. terebrans. ThreeIps species displayed varying degrees of cross-attraction as well as to theDendroctonus pheromonal blends. More specifically,I. calligraphus was attracted toI. avulsus and, to a very limited extent, also to the maleD. terebrans pheromonal blend.I. avulsus was somewhat more cross-attractive thanI. calligraphus and showed attraction to the pheromonal blends of femaleD. frontalis, male and femaleD. terebrans, maleI. calligraphus, and maleI. grandicollis. I. grandicollis showed the greatest degree of cross-attraction, particularly in response to theDendroctonus pheromonal blends.Research support in part by CSRS grant 86-CRCR-1-2270, NATO grant CRG.0710/86 and Texas Agricultural Experiment Station project MS1525 (while M.T.S. and T.L.P. were with Texas A&M University). The findings, opinions, and recommendations expressed herein are those of the authors and not necessarily those of the U.S. Department of Agriculture.     

Density-Dependent Reduction and Induction of Milkweed Cardenolides by a Sucking Insect Herbivore

The effect of aphid population size on host-plant chemical defense expression and the effect of plant defense on aphid population dynamics were investigated in a milkweed-specialist herbivore system. Density effects of the aposematic oleander aphid, Aphis nerii, on cardenolide expression were measured in two milkweed species, Asclepias curassavica and A. incarnata. These plants vary in constitutive chemical investment with high mean cardenolide concentration in A. curassavica and low to zero in A. incarnata. The second objective was to determine whether cardenolide expression in these two host plants impacts mean A. nerii colony biomass (mg) and density. Cardenolide concentration (microgram/g) of A. curassavica in both aphid-treated leaves and opposite, herbivore-free leaves decreased initially in comparison with aphid-free controls, and then increased significantly with A. nerii density. Thus, A. curassavica responds to aphid herbivory initially with density-dependent phytochemical reduction, followed by induction of cardenolides to concentrations above aphid-free controls. In addition, mean cardenolide concentration of aphid-treated leaves was significantly higher than that of opposite, herbivore-free leaves. Therefore, A. curassavica induction is strongest in herbivore-damage tissue. Conversely, A. incarnata exhibited no such chemical response to aphid herbivory. Furthermore, neither host plant responded chemically to herbivore feeding duration time (days) or to the interaction between herbivore initial density and feeding duration time. There were also no significant differences in mean colony biomass or population density of A. nerii reared on high cardenolide (A. curassavica) and low cardenolide (A. incarnata) hosts.     

Ancestral semiochemical attraction persists for adjoining populations of siblingIps bark beetles (Coleoptera: Scolytidae)

Three species ofIps pine bark beetles in Hopping's group IX (S.L. Wood'sgrandicollis group),Ips confusus, I. lecontei, andI. paraconfusus, are parapatrically distributed in the American Southwest. They share post-Pleistocene altitudinal ecotones with their host pines. Adjacent to these areas of host overlap, we tested the hypothesis that aggregation pheromones produced by male beetles and/or host volatiles are sufficient to elicit the speciesspecific colonization behaviors typical of these threeIps species in nature. A more distantly related species,I. pini (Hopping's group IV, S.L. Wood'spini group) was used for outgroup comparison. Under the influence of pheromone, males ofI. confusus andI. paraconfusus do not discern among unin-fested log bolts of host and nonhost pine prior to bark contact. Males responding to pheromones emanating from infested bolts are similarly undiscriminating. Females ofI. confusus andI. lecontei olfactorily discern the combination of conspecific males in host pine from other possible beetlepine combinations; females ofI. paraconfusus do not. FemaleI. pini discerned conspecific pheromone from that ofI. lecontei. The bark beetle predator,Enoclerus lecontei, is attracted by, but does not discriminate among, the male-produced volatiles of these Group IXIps species. These results support a hypothesis that divergence in pheromonal responses by these group IXIps species has evolved following their speciation, having been manifested first in the female sex. Evolutionarily, the derived pheromonal messages have preceded their behavioral discrimination by these beetles. Additional speciesspecific cues may operate between the sexes in the field that may preclude heterospecific pairings.     

Interspecific response to sex pheromones,and calling behavior of severalAttagenus species (Coleoptera: Dermestidae)

Females of severalAttagenus species demonstrated calling behaviors similar to those previously reported forA. elongatulus. Attagenus rufipennis females did not call until they were 12–14 days old. OtherAttagenus species called at approx. 4 days of age. All species exhibited diurnal periods of calling activity. Interspecific pheromone responses were tested, withA. megatoma megatoma, A. megatoma canadensis, A. megatoma japonicus, andA. schaefferi spurcus showing equal cross-responses. Male response to females was demonstrated inA. rufipennis andA. bicolor. Attagenus rufipennis, bicolor, andelongatulus males responded only to female extracts of their own species.Mention of a proprietary product does not constitute an endorsement by the USDA.     

Allelopathic interactions among algae

Five species of green algae isolated from the Cleveland County, Oklahoma, area and a commercially obtained yellow-green alga were tested for allelopathic interactions. Axenic cultures ofPandorina morum Bory were stimulated in three sterile filtrates from nonaxenic cultures ofScenedesmus incrassatulus var.mononae G.M. Smith, with the oldest filtrate showing the least stimulation. By measuring the growth of axenic cultures inoculated into sterile filtrates of old cultures, instances of inhibition and stimulation were recorded in three screening experiments.Cosmarium vexatum West filtrate was inhibitory to the five other species, a characteristic probably important in its role of producing waterblooms in ponds and swamps. The allelopathic effects of filtrates of the five other species onBolrydium becherianum Vischer could be a key to its restriction to terrestrial sites. Instances of heat lability of the active substances were noted. These interactions, both allelopathic and stimulatory, probably play a significant role in the succession of algal blooms in nature.     

国外生物降解聚合物的种类及主要组分

据１９９６～１９９８年国外有关文献的汇集,由美,日,德等国主要研制,生产的生物降解聚合物种类为：１,单一型生物降解聚合物;（１）合成酯（酸）类;（２）淀粉基材料;（３）天然高分子材料;２、复合型生物降解聚合物;（１）不同种类的烃基互聚物;（２）烃酯（酸）／聚酯（３）脂肪族聚酯／芳香族聚酯共聚物;（３）淀粉基复合型,（５）光／生物降解聚合物;３、可生物降解水溶性聚合物。     

Plant-determined variation in the cardenolide content,thin-layer chromatography profiles,and emetic potency of monarch butterflies,Danaus plexippus L. Reared on milkweed plants in California: 2.Asclepias speciosa

The pattern of variation in gross cardenolide concentration of 111Asclepias speciosa plants collected in six different areas of California is a positively skewed distribution which ranges from 19 to 344 g of cardenolide per 0.1 g dry weight with a mean of 90 g per 0.1 g. Butterflies reared individually on these plants in their native habitats ranged from 41 to 547 g of cardenolide per 0.1 g dry weight with a mean of 179 g. Total cardenolide per butterfly ranged from 54 to 1279 g with a mean of 319 g. Differences in concentrations and total cardenolide contents in the butterflies from the six geographic areas appeared minor, and there were no differences between the males and the females, although the males did weigh significantly more than females. The uptake of cardenolide by the butterflies was found to be a logarithmic function of the plant concentration. This results in regulation: larvae which feed on low-concentration plants produce butterflies with increased cardenolide concentrations relative to those of the plants, and those which feed on high-concentration plants produce butterflies with decreased concentrations. No evidence was adduced that high concentrations of cardenolides in the plants affected the fitness of the butterflies. The mean emetic potencies of the powdered plant and butterfly material were 5.62 and 5.25 blue jay emetic dose fifty units per milligram of cardenolide and the number of ED₅₀ units per butterfly ranged from 0.28 to 6.7 with a mean of 1.67. Monarchs reared onA. speciosa, on average, are only about one tenth as emetic as those reared onA. eriocarpa. UnlikeA. eriocarpa which is limited to California,A. speciosa ranges from California to the Great Plains and is replaced eastwards byA. syriaca L. These two latter milkweed species appear to have a similar array of chemically identical cardenolides, and therefore both must produce butterflies of relatively low emetic potency to birds, with important ecological implications. About 80% of the lower emetic potency of monarchs reared on A. speciosa compared to those reared onA. eriocarpa appears attributable to the higher polarity of the cardenolides inA. speciosa. Thin-layer Chromatographie separation of the cardenolides in two different solvent systems showed that there are 23 cardenolides in theA. speciosa plants of which 20 are stored by the butterflies. There were no differences in the cardenolide spot patterns due either to geographic origin or the sex of the butterflies. As when reared onA. eriocarpa, the butterflies did not store the plant cardenolides withR _f values greater than digitoxigenin. However, metabolic transformation of the cardenolides by the larvae appeared minor in comparison to when they were reared onA. eriocarpa. AlthoughA. eriocarpa andA. speciosa contain similar numbers of cardenolides and both contain desglucosyrioside, the cardenolides ofA. speciosa overall are more polar. ThusA. speciosa has no or only small amounts of the nonpolar labriformin and labriformidin, whereas both occur in high concentrations inA. eriocarpa. A. speciosa plants and butterflies also contain uzarigen, syriogenin, and possibly other polar cardenolides withR _f values lower than digitoxin. The cardenolide concentration in the leaves is not only considerably less than inA. eriocarpa, but the latex has little to immeasurable cardenolide, whereas that ofA. eriocarpa has very high concentrations of several cardenolides. Quantitative analysis ofR _f values of the cardenolide spots, their intensities, and their probabilities of occurrence in the chloroform-methanol-formamide TLC system produced a cardenolide fingerprint pattern very different from that previously established for monarchs reared onA. eriocarpa. This dispels recently published skepticism about the predictibility of chemical fingerprints based upon ingested secondary plant chemicals.Lepidoptera: Danaidae.Apocynales: Asclepiadaceae.This study was supported by U.S. National Science Foundation grants DEB 75-14265 and 78-10658 to Amherst College and BSR-8119382 to the University of Florida with L.P. Brower as Principal Investigator and DEB75-14266, DEB78-15419, and DEB-81-19391 to the University of California at Davis with J.N. Seiber as Principal Investigator.     

Influence of life history differences of two tachinid parasitoids ofHelicoverpa zea (Boddie) (Lepidoptera: Noctuidae) on their interactions with glandular trichome/methyl ketone-based insect resistance in tomato

The effects of glandular trichome/methyl ketone (2-tridecanone and 2-undecanone) -based insect resistance in the wild tomato,Lycopersicon hirsutum f.glabratum C.H. Mull, accession PI 134417, onArchytas marmoratus (Townsend) andEucelatoria bryani (Sabrosky) (Diptera: Tachinidae), both parasitoids ofHelicoverpa (=Heliothis)zea (Boddie) (Lepidoptera: Noctuidae), were investigated in the laboratory.A. marmoratus deposits larvae (planidia) on the foliage of its host's food plant; planidia attach to passing hosts, penetrate the cuticle, and develop in the host pupae.E. bryani larviposits directly into its host; its larvae develop in the host larva.A. marmoratus planidia are killed by glandular trichomes of PI 134417 and also by trichomes of hybrid lines with no methyl ketones. The methyl ketones are toxic to planidia, but at least part of the effect is due to other factors, possibly physical entanglement. Both species can be affected indirectly by methyl ketones in the diet of the host. 2-Undecanone reduces the percentage ofA. marmoratus larvae that reach pupation. This effect is evidently due to premature death and desiccation of the host pupa caused by 2-undecanone. 2-Tridecanone in host diets had no effect onA. marmoratus. InE. bryani, 2-tridecanone in the diet of the host reduced the number of parasitoids yielded by each parasitized host, although not the overall percentage of hosts parasitized. 2-Undecanone in the diet of the host had no effect onE. bryani.We thank M. Woodall for typing; V.B. Covington, D. Bumgarner, and B. O'Brien for technical assistance; L.A. Jones for assistance with gas chromatography; P.H. Adler for supplyingE. bryani puparia to initiate colony; and Drs. F. Gould, G.C. Rock, and M. Barbercheck for comments.     

Modified dynamic matrix control

DMC (Dynamic Matrix Control) has been used successfully in industry for the last decade. It can deal with constraints and unusual dynamic behavior directly. It also shows a good control performance for the servo problem. Relatively, it can’t reject disturbances systematically. We propose a modified DMC method to control the regulatory process more efficiently. The proposed DMC method makes the control output by subtracting the estimated disturbance from the control output of the original DMC. Here, the disturbance is estimated by a new disturbance estimator. It shows better control performances than the original DMC.     

Soil nutrient depletion by agricultural production in Southern Mali

The degree of soil mining by agricultural production in Southern Mali is assessed by calculating nutrient balances: differences between the amount of plant nutrients exported from the cultivated fields, and those added to the fields. Export processes include extraction by crops, losses due to leaching, to erosion, and to volatilization and denitrification. Inputs include applications of fertilizer and manure, restitution of crop residues, nitrogen fixation, atmospheric deposition of nutrients in rain and dust, and enrichment by weathering of soil minerals. Nutrient balances are calculated for N, P, K, Ca, and Mg. Both pessimistic and optimistic estimates are given.The resulting figures indicate, even when the most optimistic estimates are used, large deficits for nitrogen, potassium and magnesium. For the region as a whole, the calculated deficits are -25 kg N/ha,-20 kg K/ha, and -5 kg Mg/ha. Further, acidification is to be expected, in particular in areas where cotton is grown. The deficits are caused by traditional cereal crops, but also by cotton and especially by groundnut. The latter two crops are fertilized, but insufficiently. It is important to note, that the negative figures are not automatic recommendations for application of a specific amount of additional fertilizer. For phosphorus and calcium the balance of the region as a whole appears to be about in equilibrium, but locally large variations may occur.Erosion and denitrification are important causes of nutrient loss, accounting respectively for 17 and 22% of total nitrogen exports. Atmospheric deposition and weathering of minerals in the soil are still important nutrient inputs that contribute as much as nutrients as organic and mineral fertilizer combined. Nutrient depletion is very large in comparison to the amount of fertilizer applied. Drastic options, such as doubling the application of fertilizer or manure, or halving erosion losses, even if feasible, would still not be enough to make up for the calculated deficits.The annual value of withdrawn nutrients, if related to prices of fertilizers, varies between 10,000 and 15,000 FCFA/ha (40-60 US $/ha). Since the estimated average gross margin from farming in this area is 34,000 FCFA/ha (123 US $/ha), soil mining appears to provide an amount equal to 40% of farmers' total income from agricultural activities.