基于损伤理论的硅藻土混凝土冻融损伤研究

通过快速冻融试验,对不同强度等级的掺硅藻土混凝土的抗冻性进行了分析.在损伤理论的基础上构建了多次冻融后混凝土劣化失效的数学模型,使用Matlab程序模拟了混凝土内部各单元点的损伤失效与时间的函数关系,并生成了混凝土的截面损伤概率图.在冻融循环时间相同的条件下对不同硅藻土掺量的混凝土进行了对比分析.结果表明:硅藻土的加入...     

Insecticidal effect of three diatomaceous earth formulations, applied alone or in combination, against three stored-product beetle species on wheat and maize

Laboratory tests were carried out to examine the insecticidal effect of three commercially available diatomaceous earth (DE) formulations on wheat and maize against three major stored-grain beetle species: Rhyzopertha dominica, Sitophilus oryzae, and Tribolium confusum. The three DEs tested were Insecto^®, PyriSec^®, and Protect-It^®. These DEs were applied alone or in all possible combinations (Insecto^®+PyriSec^®, Insecto^®+Protect-It^®, PyriSec^®+Protect-It^®, and all three DEs together), at three (total) dose rates: 0.25, 0.5, and 0.75 g/kg of each commodity. Adults of the above species were exposed to the treated commodities for 7 d at 26 °C, and 65% r.h., and after this interval the mortality was measured. For each species, adult mortality was significantly affected by the type of DE, the commodity, and the dose rate. All DEs were less effective against T. confusum, where mortality did not exceed 67%, in comparison with the other two species, where 100% mortality was achieved in some combinations. For all species tested, all DEs were more effective on wheat than on maize. Generally, the mix of two or three DEs was more effective than the application of one DE, for all species and commodities. The results of the present work clearly indicate that a blending of several DEs together may produce a new DE formulation that is highly effective at low dose rates.     

Comparison of the desiccation effects of marine and freshwater diatomaceous earths on insects

The desiccating effects of two different types of diatomaceous earths (DEs), of freshwater and marine origin, applied by two different methods, were compared on four species of insects, Cryptolestes ferrugineus, Rhyzopertha dominica, Sitophilus oryzae and Sitophilus granarius. The purpose was to investigate the performance of DEs, including their abrasive and absorptive effects through the accumulation of silica dusts on the insect cuticle, resulting in death of the insects by desiccation. The data obtained showed that similar insects treated with the same type of diatom, but applied either by spraying or dusting, did not have the same initial mortality rate.

After examining and comparing the data obtained, it appeared that weight loss at death of insects subjected to the action of sprayed DEs was slightly less than for insects subjected to dust application, while mortality was slightly more rapid during the observation period. The extra weight of dusted insects was ascribed to greater adherence of dust particles to the treated insects.     

异丙醇生产技术进展

概述了子异丙醇的用途，产量，消费，生产方法及技术进展，着重介绍了以丙烯为原料的直接水合法生产工艺路线，并对我国异丙醇的生产提出了一些建议。     

Technical report on the compression,structure, and creep behaviors of lacustrine soil deposits in Bogotá, Colombia

This technical report on the compression behavior of soft soils in the Colombian capital, Bogotá, was conducted because the city’s recent construction history has led to excessive settlement of soils in the city over the last forty years. Several studies have shown the city’s soil to contain unusually high concentrations of diatoms. The stationary piston method was used to obtain samples from depths of between five and 100 m. Samples were subsequently examined in the laboratory, being subjected to triaxial and oedometer compression tests, and tested also for Atterberg limits and grain size distributions. Test results for undisturbed soil returned very high liquid limit values, compressibility indices C_C, secondary compression coefficients C_α, and soil structure effects. Some samples showed particle mixtures of different sizes, mineralogy, and diatom concentrations. Although high C_C and C_α indices explain the excessive settling of the city’s buildings, most construction projects do not currently take settlement caused by secondary compression into account. This report shows that secondary compression is an important parameter in the total settlement of buildings in Bogotá and that, furthermore, settlement is also affected by geological history. Finally, useful correlations such as the relationship between the liquid limit, C_α and geological history are presented.     

Laboratory evaluation of diatomaceous earths, when applied as dry dust and slurries to wooden surfaces, against stored-product insect and mite pests

The efficacy of Silico-sec^® and Diasecticide^™ applied as dry dust and slurry applications to wooden surfaces was assessed in the laboratory against adult Sitophilus granarius, and Lepidoglyphus destructor and against larvae of Ephestia kuehniella. Wood was used as the test substrate as it was considered to present a realistic challenge to efficacy due to its 3-dimensional structure. Against the insects, doses of 10 g/m² Silico-sec^® and 20 g/m² Diasecticide^™ were evaluated. Against the mite 1 and 3 g/m² of the respective Silico-sec^® and Diasecticide^™ dry dusts and 20 g/m² of the slurries were assessed. The effects on the insects and mites were assessed one day, 4 weeks and 12 weeks after treatment of the wood. Mortalities were evaluated after exposure times of 24 h and 7 days for the mite and insects, respectively, at conditions of 15 °C and 80% r.h., chosen to represent typical UK conditions after harvest. Of the four treatments, the Silico-sec^® dry dust was the most effective against all the pest species, producing 80-95, 100 and 93-100% mean mortalities of S. granarius, E. kuehniella and L. destructor, respectively, over the 12-week experimental period. The Diasecticide^™ dry dust produced <11, >99 and 68-93% mortalities of the respective species. The slurry treatments were less effective than the dry dusts with the Silico-sec^® slurry producing 29-46, 83-97 and <8% mortalities of the respective species and the Diasecticide^™ slurry being ineffective against S. granarius and L. destructor and producing 34-61% mortality of E. kuehniella. This study built on information gained from preliminary work and assessed DEs against tolerant pests on a surface where control was expected to be difficult, in order to provide dose recommendations which would encompass a range of infestation situations in the field.     

Toxic and behavioural effects of different modified diatomaceous earths on the German cockroach, Blattella germanica (L.) (Orthoptera: Blattellidae) under simulated field conditions

Defined populations of German cockroaches were observed after exposure to deposits (25 g/m²) of various modified and un-modified diatomaceous earth (DE) formulations by using a computer-aided device measuring motility, circadian rhythm, and mortality under defined environmental and climatic field-simulating conditions. In a humid climate (85% r.h.) with water and food offered ad libitum, complete population eradication could be achieved within 10 days with three out of seven DE formulations tested. Results revealed two basic factors affecting mortality: (a) formulations containing freshwater diatoms from Spain were significantly more effective than those originating from marine diatoms purchased from Fur Island, Denmark (P<0.0001), and (b) the higher the degree of coating with a silica-aerogel to increase oil-carrying capacity, the greater the efficacy (P<0.0001 to 0.07). Exposure to DEs resulted in complete disruption of the species-specific circadian rhythm of German cockroach populations with six out of seven DE formulations investigated. A remaining rudimentary circadian rhythm was found after exposure to one formulation. It is concluded that strongly hydrophobic formulations of DE can be used for effective cockroach control even in tropical environments, especially as part of a least-toxic Integrated Pest Management control strategy. Nevertheless, it remains unclear to what extent newly developed DEs, coated or formulated with different chemical compounds resulting in modified surface characteristics, could potentially produce adverse health effects to humans.     

Mortality and progeny production of four stored-product insect species on three grain commodities treated with Beauveria bassiana and diatomaceous earths

Laboratory bioassays were conducted to estimate the effectiveness of the entomopathogenic fungus Beauveria bassiana (Bals.-Criv.) Vuill. (Hypocreales: Cordycipitaceae) at 1.5 × 10⁸ and 1.5 × 10¹⁰ conidia/kg grain alone or mixed with the diatomaceous earths (DEs) Protect-It at 150 ppm and DEBBM at 50 ppm against adults of the rusty grain beetle, Cryptolestes ferrugineus Stephens (Coleoptera: Laemophloeidae), the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae), the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and the psocid, Liposcelis paeta Pearman (Psocoptera: Liposcelididae). The adult insects were exposed to treated grains for 7, 14 and 21 days. For progeny emergence data, the treated units were remained under the same conditions for 62 days for all beetles and 30 days for psocids. The results revealed significant differences in mortalities of insect species among treatments and grains. The combined use of B. bassiana, at the highest dose, and DE increased adult mortalities of all species. In general, the treatments were least effective against T. castaneum and most effective against L. paeta. More numbers of dead insects were found on wheat than on rice or maize. The emergence of progeny was considerably reduced on grains treated with B. bassiana, at the highest dose, plus DE. The results of the present study suggest that the effectiveness of B. bassiana is fortified by the addition of DEs, but it varies among exposed insect species and commodities.     

煤矸石和硅藻土对熔模石膏型性能的影响

向石膏中加入不同的耐火填料,在同一水膏比下,分别测试分析石膏浆料的流动性、凝结时间,石膏铸粉的湿强度、焙烧后的强度、线收缩率和显微组织。结果表明,煤矸石和硅藻土同时加入石膏粉中,焙烧后的石膏晶粒间搭接良好、紧密度高、铸型强度高。在煤矸石加入量为20%且硅藻土加入量为10%时,石膏浆料的流动直径为90mm,初凝时间为7min,终凝时间为17min,湿抗折强度为2.02MPa,抗压强度为2.3MPa,焙烧后的抗折强度为0.458MPa,抗压强度为1.07MPa,线收缩率为0.320%。     

新型高效精细过滤技术——硅藻土过滤

综术字新型高效精细过滤技术－－硅藻土过滤的工作原理、技术特点及设备类型,介绍硅藻土过滤技术在国内外的工业应用进展。