桑车20MnCr5钢主动轴螺旋齿断裂分析

某大众试验车行驶8．6万公里后其主动轴螺旋齿断裂。采用宏观检验、金相分析、化学成分分析、应力测试等手段对失效件取样分析，结果表明，螺旋齿断裂是由于轴向定位松动，造成齿轮局部受力集中，在疲劳源基础上发展成裂纹，裂纹进一步扩展导致断裂。     

GH4169缺口件多轴加载下应力应变场的有限元分析

采用GH4169缺口试件在650 ℃下进行了高温拉扭疲劳断裂试验,利用ANSYS 6 1 有限元分析软件计算试件缺口周围的应力应变场,确定出试件在各种载荷状况下的应力集中系数。计算结果表明,该有限元建模方式是合理的,为以后缺口件的寿命预测过程奠定了基础。     

Tasting green leaf volatiles by larvae and adults of Colorado potato beetle,Leptinotarsa decemlineata

Larvae and adults of the Colorado potato beetle,Leptinotarsa decemlineata (Say), are shown to have galeal gustatory cells that are highly sensitive to distillate of potato leaf extracts, (E)-2-hexen-1-ol, (E)-2-hexenal, and other saturated and unsaturated six-carbon alcohols. In larvae and adults, the sensory response patterns elicited by leaf homogenate, leaf distillate and a mixture of these two extracts differ in subtle ways. Beetle larvae feed most readily on Millipore disks treated with leaf homogenate and the mixture, but they did not feed on disks treated with leaf distillate. The differences in behavioral response and sensory input are used to derive a potential gustatory code that may stimulate different levels of feeding. This code may be disrupted by compounds present in nonhost leaves, thus leading to reduced feeding. Possible interactions of sapid leaf volatiles, amino acids, sugars, and potentially deterrent plant compounds are discussed.     

Isolation of feeding deterrents against argentine stem weevil from ryegrass infected with the endophyteAcremonium loliae

Infection of ryegrass (Lolium perenne) by an endophytic fungus (Acremonium loliae) confers resistance against the Argentine stem weevil (Listronotus bonariensis). Extracts from ryegrass clones, infected and uninfected withA. loliae, were compared in a feeding choice bioassay, and several fractions were identified which affected stem weevil feeding behavior. One stem weevil feeding deterrent, peramine C₁₂H₁₇N₅O, has been isolated from infected ryegrass and partially characterized as a basic indole derivative. Extracts from culturedA. loliae had no effect on stem weevil feeding behavior nor was peramine detected in the fungal cultures examined. Peramine and the other active substances are hydrophilic in contrast to the lipophilic properties reported for the neurotoxic lolitrems also isolated from ryegrass infected withA. loliae and associated with causing ryegrass staggers disorder in livestock. It is suggested that ryegrass staggers and stem weevil feeding deterrency may arise by different biochemical mechanisms.     

AXIAL PHASES DISTRIBUTION AND HOMOGENIZATION IN THREE-PHASE FLUIDIZED BEDS

We have investigated the axial distribution of the liquid phase in a three-phase fluidized bed in which the particles were glass beads of two different diameters, 710-850 μm and 2 mm. Two methods were used to reduce the axial heterogeneity and homogenize the bed: the use of packing elements and the addition of a small quantity of a high molecular weight polymer. The use of packing elements was shown to be very efficient in controlling phases distribution in the bed. The packing consisted of 1 mm thick steel horizontal plates punched and stretched to obtain parallelogram-shaped openings. The addition of a high molecular weight polyisobutylene (BASF Oppanol B246, M_u, =6.15 Lo⁶) on the phase distribution was also studied. Low polymer concentrations up to 397 ppm (based on the liquid phase) were investigated. The addition of the polymer reduced bubble coalescence and allowed for a better distribution of the phases.     

Different feeding and gustatory responses to ecdysone and 20-hydroxyecdysone by larvae of the silkworm,Bombyx mori

The feeding and gustatory responses to ecdysone and 20-hydroxyecdysone were investigated in the silkworm,Bombyx mori. 20-Hydroxyecdysone reduced feeding response strongly in fourth- and fifth-instar larvae, whereas ecdysone had no effect on feeding response. 20-Hydroxyecdysone stimulated the R receptor, the receptor to feeding deterrents, to a great degree. By contrast, ecdysone was much less effective for stimulating the R receptor. These results indicate that ecdysone and 20-hydroxyecdysone have different effects on feeding response due to different interactions with mouthpart chemoreceptors.     

Hydrodynamics and liquid phase axial mixing in orifice pipe reactor

Two phase flow in a horizontal pipe, with orifice plates placed at regular intervals as obstructions, was studied for the effect of phase velocities on flow patterns, fractional phase hold-ups, pressure drop and liquid phase axial dispersion. Radioactive technetium-99m (as an aqueous solution of sodium pertechnatate) was used as tracer. A pulse injection technique with two point measurements was employed. Three different orifice diameters were used (8 mm, 16 mm, and 20 mm) in a pipe diameter of 32 mm. The orifice spacing was 500 mm in all cases. Superficial gas (air) velocity was varied over a range from 0.02 m/s to 1.0 m/s and superficial liquid (water) velocity from 0.03 m/s to 0.85 m/s. Different flow patterns under different flow conditions were identified and a generalised flow map is presented. Variations in hold-ups and pressure drop with flow patterns have been explained. Rational correlations have been developed for fractional phase hold-ups and pressure drop. A preliminary comparison of two phase gas-liquid flow in a horizontal pipe with orifice obstructions (to be called orifice pipe reactor), as a gas-liquid contacting device, is made with a conventional bubble column reactor. Recommendations have been made for future work.     

Developmental, Gustatory, and Behavioral Responses of Leafroller Larvae, Choristoneura rosaceana, to Tannic Acid and Glucose

Soluble sugars are essential nutrients generally perceived as phagostimulants to most insects studied. However, tannins are known as digestibility reducers, hence deleterious to caterpillar development, and as deterrents as well. Previous work demonstrated that larvae of the polyphagous oblique-banded leafroller, Choristoneura rosaceana, performed better when reared on a control + 0.5% tannic acid diet than on the standard control diet and that larvae reared on a control + 5% glucose diet had slower development and reduced survival. This study was designed to elucidate the behavioral and neurophysiological components of the larval responses to tannic acid and glucose. C. rosaceana larvae were reared individually from the first to the sixth instar on one of four different artificial diets: (1) control; (2) control + 5% glucose; (3) control + 0.5% tannic acid; (4) control + 5% glucose + 0.5% tannic acid. After 14 days, larvae reared on the control + 5% glucose diet had not developed past the fourth instar, whereas a considerable proportion of larvae reared on the control + 0.5% tannic acid diet had already attained the pupal stage. Insects reared on the control or the control + 5% glucose + 0.5% tannic acid diet had intermediate development, with most larvae in the fifth instar. In addition, once the mid-sixth instar was reached, the feeding preferences to 25 and 300 mM glucose, 25 mM tannic acid, and 25 mM glucose + 25 mM tannic acid over water were assessed in two-choice tests. Feeding affected preference. Control-reared insects preferred feeding on treatments containing glucose and were not deterred by tannic acid. However, larvae that had been exposed to tannic acid during their development were deterred by tannic acid and their glucose discrimination was impaired. The sensitivity to glucose was also examined from neurophysiological recordings by stimulating the sugar-sensitive cell (cell 1) on the lateral styloconic sensillum of the maxillary galea with increasing concentrations of glucose (1, 10, 25, 50, 100, 200, 300, and 500 mM). We also determined whether tannic acid was phagostimulatory, since insects develop relatively quickly on a diet containing this compound, by testing 1 mM tannic acid, 1 mM tannic acid + 300 mM glucose, and 300 mM glucose on the lateral styloconic sensilla. The traces indicated that 1 mM tannic acid was not detected by any of the four chemosensory cells in these sensilla. The combination of tannic acid and glucose produced no spikes from the sugar-sensitive cell, whereas a prominent spike activity resulted with 300 mM glucose. We concluded that, although C. rosaceana larvae develop faster on a tannic acid diet, this compound is not a phagostimulant. The converse is true for glucose; i.e., it stimulates the sugar-sensitive cell in the lateral styloconica in a concentration-dependent fashion. Previous dietary experience changes the sensory and behavioral responses of C. rosaceana to glucose. Our findings imply that not all compounds that are phagostimulatory are necessarily beneficial to an insect's fitness. Therefore, developmental studies should be interpreted in conjunction with behavioral and physiological data.     

Insect antifeedant activity associated with compounds isolated from species ofLonchocarpus andTephrosia

The antifeedant activity of a series of 21 chalcones, flavanes, and flavanones isolated from the generaLonchocarpus andTephrosia (Leguminosae) was assessed by behavioral and electrophysiological bioassays against larvae ofSpodoptera littoralis andS. exempta. The antifeedant activity is related to the molecular structure of the compounds, and possible modes of interaction with the insect taste receptors are discussed.     

GRIP管混凝土组合结构压弯构件非线性全过程分析

本文应用细观力学、经典层板理论、平截面假定、FRP约束混凝土本构模型及数值积分对GFRP管混凝土组合结构压弯构件进行了非线性全过程分析。通过理论计算发现GFRP管混凝土组合结构能有效地提高构件的承载力，且构件具有良好的变形能力。FRP壳体参与承载且有效地约束混凝土的变形，显著提高核心混凝土强度和变形能力。文中讨论了轴压比、长细比、径厚比、混凝土强度等级、纵筋配筋率、铺层角变化对极限水平荷载和极限水平位移的影响，从而得到了一些有益的结论。