商品混凝土机械的选型与使用(七)──混凝土泵车的选型

1979年我国在上海宝山钢铁总厂一期工程建设时曾从国外引进了19辆混凝土泵车，在使用的五年中累计泵送混凝土达160万m3，对工程的顺利进展起到了重要作用，并积累了经验，为国内推广使用混凝土泵车打下了基础。进入80年代以后，从德国、日本等国继续引进了相当数量的混凝土泵车，并在建筑施工中得到了推广应用。1995年10月上海建工（集团）总公司集中了26辆混凝土泵车，用于上海世界贸易商城基础底板10．7m深坑的一次性浇筑施工，连续浇筑了26h，共浇筑混凝土2．4万m’，表明了混凝土泵车在现代化施工中所起的重要作用，目前，在国家重点建…     

隧道混凝土硫酸盐侵蚀病害分析与防治措施

隧道混凝土结构在长时间经受硫酸盐矿物质地下水的侵蚀作用下，易产生结晶分层、疏松剥离，进而导致结构强度下降，对隧道的正常使用和运营构成威胁。结合隧道硫酸盐侵蚀病害特性展开分析，针对硫酸盐病害侵蚀作用下隧道实施地下水防治加固治理，在借助原有混凝土结构承载作用基础上，根据划区防治、因地制宜的准则，综合分析应用硫酸盐混凝土套拱加固技术，建立系统的硫酸盐病害加固防治措施，制定已渗漏部位处置方案，实现混凝土结构稳定性提升。     

混凝土锯切加工过程的基本特征

通过金刚石单颗粒划伤、金刚石单个节块锯切和金刚石锯片锯切系列试验，对混凝土锯切加工过程中的切屑形态和切削区表面形貌，以及切削力等基本特征进行了详细讨论。结果表明：金刚石锯片锯切混凝土的过程表现为高速锯切过程中金刚石锯片的冲击引起混凝土表层断裂破碎，水泥石子等在切削区内层受到金刚石磨粒的微切削作用形成粉屑，以及钢纤维和钢丝发生金属塑性变形断裂或被拔拉而断裂的过程。在粘性水泥粉屑以及金刚石磨粒的挤压作用下，多种形态的切屑易粘结成团，并粘附到混凝土锯切表面和锯片节块上而导致锯片堵塞。     

高温下钢筋混凝土构件力学性能的研究

用数值计算方法分析了高温下构件的混凝土保护层厚度对主筋力学性能的影响，分析了抗弯刚度与构件经受火灾作用时间的关系，并与实验结果进行了对比。对高温后的构件，研究了构件剩余承载力的计算方法。并从经济和安全角度考虑，对有防火要求的普通混凝土受弯构件，提出了对混凝土保护层厚度取值建议。     

小浪底工程中的工程机械

ＲＯＴＥＣ塔带机美国ＲＯＴＥＣ公司生产的塔带机是兼有塔式起重机和混凝土输送与浇注功能于一身的一种设备。在其他水电大坝工程混凝土作业中曾起到了重要作用，目前在小浪底和三峡大坝工程中也不例外。ＲＯＴＥＣ塔带机的主要特点是：一是单位时间混凝土输送量极大，生...     

南方路机JS系列双卧轴混凝土搅拌机

ＪＳ系列双卧轴搅拌机是福建南方路面机械有限公司自行研究开发的新型搅拌主机。按单循环的混凝土产量可分为ＪＳ１０００、ＪＳ１５００、ＪＳ２０００、ＪＳ３０００、ＪＳ３５００和ＪＳ４０００等几种机型，可配置组成５０～２４０ｍ３／ｈ混凝土搅拌站（楼）或组成多主机的搅拌楼，特别适用于各种管桩、构件和城市商品混凝土搅拌。 搅拌装置 搅拌主机工作时，搅拌轴相向转动，在搅拌臂与叶片的作用下，物料呈环形运动，同时在搅拌臂的剪切作用下，在较短的时间内达到充分拌和的目的。为了适应不同工况和骨料粒径的要求，搅拌臂可在轴上…     

腹筋对混凝土构件力学性能的影响试验研究

依托尼日利亚阿布贾城铁一期工程站房项目，通过试验手段研究了腹筋对轻骨料混凝土受剪力学特性的影响。将不同腹筋配筋率的轻骨料混凝土试件与素混凝土试件进行对比分析，从跨中挠度、裂缝发展和受剪承载力等角度，分析了腹筋在混凝土构件中发挥的作用。研究结果表明：配筋率为1.13%时加筋效果最优，腹筋能对混凝土中荷载的传递路径进行优化，可以有效提高试件的承载力和刚度，减少跨中挠度变形。跨中挠度与截面高度呈负相关。名义抗剪强度由大到小依次为破坏阶段、服役阶段和斜裂阶段。随着截面高度的增加，各工况下的名义极限强度均出现减小，名义极限强度与截面高度呈现负相关关系。     

公路桥梁大体积混凝土常见裂缝成因分析及控制方法

对于大体积混凝土使用来说，施工前后容易发生裂缝问题，影响公路桥梁的施工质量，为此需要对大体积混凝土施工工艺进行改进优化。在施工过程中，要注意增强混凝土自身的拉伸强度，做好对混凝土的保温工作。在对混凝土进行浇筑以前，要防止混凝土出现过热的问题，同时也要做好对混凝土的保温，防止大体积混凝土因为热胀冷缩发生裂缝的问题。     

钢管混凝土构件在爆炸冲击荷载作用下的动力仿真分析

采用有限元分析软件ANSYS/LS-DYNA对圆钢管混凝土结构构件在爆炸冲击荷载作用下的动力响应特性进行了数值模拟.通过分析钢管混凝土构件在不同折合距离下的侧向位移和核心混凝土的失效破坏情况,得到在爆炸冲击荷载作用下随着折合距离的增大,钢管混凝土构件的整体变形逐渐减小,钢管和核心混凝土的破坏程度也逐渐减小,特别是当折合...     

建筑工程施工中大体积混凝土裂缝控制技术

为解决大体积混凝土裂缝问题，以某地区建筑项目为例，设计针对大体积混凝土在施工中的裂缝控制技术。为确保混凝土强度等级达到C40标准，按照规范选择混凝土制备原材料，设计建筑工程施工中大体积混凝土配合比。用φ25mm的钢管作为冷却水输送装置，将冷却水排入管道中，调节冷却水温度，控制混凝土内外温差过大。从湿度控制与温度控制两个方面，设计大体积混凝土养护施工，以实现对混凝土裂缝的控制。设计实例应用实验，通过实践证明：该方法可以有效控制混凝土在完成浇筑养护阶段的内外温差，以此种方式，降低作业面裂缝数量，提高混凝土浇筑施工质量。     

Effects of polydatin on the proliferation,migration, and invasion of ovarian cancer

To investigate the effects of polydatin on the proliferation, migration, and invasion of ovarian cancer, the change of proliferative ability, migration ability, and invasive ability of human ovarian cancer cell OVCAR-3, A2780, and HO-8910 was detected by using polydatin and up-regulating PI3K. The anticancer activity and mechanism of polydatin in ovarian cancer were analyzed. Polydatin could effectively inhibit the proliferation, migration, and invasion of OVCAR-3, A2780, and HO-8910, and inhibit the expression of PI3K protein. After the expression level of PI3K protein was up-regulated, the inhibitory effect of polydatin on the proliferative ability, migration ability, and invasive ability of OVCAR-3, A2780, and HO-8910 significantly decreased, suggesting that PI3K was the target of polydatin. Therefore, we concluded that polydatin could inhibit the proliferation, migration, and invasion of ovarian cancer cells by inhibiting the expression of PI3K protein, which provides an experimental basis for polydatin in the treatment of ovarian cancer.     

微波消解-电感耦合等离子体质谱法同时测定茶叶中42种元素

建立了电感耦合等离子体质谱法（IcP—Ms）标准模式和优化的碰撞池模式（CCT）结合同时测定茶叶中Li、Be、Mg、Al、V、Cr、Mn、Fe、Co、Ni、Cu、Zn、Ga、As、Se、Sr、Mo、Ag、Cd、Sn、Sb、Cs、Ba、Tl、Pb、Bi和16种稀土元素共42种元素的方法。样品经过微波消解,以Ge、In、Re为内标消除基体干扰,通过碰撞池技术消除多原子质谱干扰测定上述元素。对于所测元素校准曲线的相关系数均大于0．9990,回收率范围为90％-110％,相对标准偏差为0．22％-3．97％,大部分元素检出限均小于0．5μg·kg^-1。该方法简便、省时、准确、灵敏度高,适用于实际样品的检测。     

Histochemical and ultrahistochemical localization of heavy metals in calf organs

Cadmium, zinc, selenium, and copper were administered, singly or in combination, orally or subcutaneously. Experiment I included 32 calves of both sexes; six received Cd (two groups), Zn, Cd, and Zn, and Cd and Se (two groups) and one group was a control. In Experiment II (21 bulls), three were given Cd, Cd, and Cu, and Cd and Zn, respectively, and one group was a control. For light microscopy, in Experiment I the highest amounts of silver granules were present in the samples of liver, small intestine, and vesicular gland of all the exposed groups; in Experiment II the most affected organs were liver, kidney, and small intestine. For electron microscopy, in Experiment I, after administration of Cd and Zn, the highest amounts of granules were seen in the cytoplasm of hepatocytes and cells of the proximal and distal renal tubules and the lowest amounts were found in glandular cells of the pancreas. Administration of Cd and Se resulted in the presence of large numbers of granules in the nuclei and nucleoli of spermatogonies. In Experiment II, ingestion of Cd and Zn in feed led to the appearance of highest amounts of granules in the nucleoli, nuclei, and cytoplasm of cells in testes, kidneys, and pancreas. Following Cd intake, the highest accumulation of granules was observed in the nucleoli of hepatocytes and cells of the proximal and distal renal tubules. Combined Cd and Cu produced the highest number of granules in cells of the proximal and distal renal tubules and in the nucleoli and nuclei of germinal epithelium.     

Two distinct events, section compression and loss of particles ("lost caps"), contribute to z-axis distortion and bias in optical disector counting

Deformation of tissue sections in the z-axis can bias optical disector counting. When samples of particle densities are not representative for the entire tissue section, significant bias of estimated numbers can result. To assess the occurrence, prevalence, extent, sequence of events, and causes of z-axis distortion, the distribution of neuronal nucleoli in thick paraffin and vibratome sections was determined in chicken, rodent, and human brain tissues. When positions of neuronal nucleoli were measured in the z-axis, nucleoli were more frequent at the surfaces (bottom and top) of tissue sections than in the core. This nonlinear z-axis distribution was not lab-, equipment-, or investigator-specific, and was independent of age, fixation quality, coverslipping medium, or paraffin melting temperature, but in paraffin sections, was highly correlated with the tilt of the knife (cutting) angle. Manipulation of subsequent tissue processing steps revealed that two events contribute to z-axis distortion. Initially, a higher density of particles results at surfaces after sectioning, apparently due to section compression. Subsequently, particles can be lost to varying degrees from surfaces during floating or staining and dehydration, resulting in "lost caps." These results may explain different degrees of z-axis distortion between different types of sections and different labs, and reinforce the importance of checking z-axis distributions as a "quality control" prior to selection of guard zones in optical disector counting. Indirect approaches to assess section quality, such as resectioning in a perpendicular plane, yield additional artifacts, and should be replaced by a direct quantitative measurement of z-axis distribution of particles.     

Immunohistochemical distribution of enkephalin, substance P, and somatostatin in the brainstem of the leopard frog, Rana pipiens

The brainstems of frogs contain many of the neurochemicals that are found in mammals. However, the clustering of nuclei near the ventricles makes it difficult to distinguish individual cell groups. We addressed this problem by combining immunohistochemistry with tract tracing and an analysis of cell morphology to localize neuropeptides within the brainstem of Rana pipiens. We injected a retrograde tracer, Fluoro-Gold, into the spinal cord, and, in the same frog, processed adjacent sections for immunohistochemical location of antibodies to the neuropeptides enkephalin (ENK), substance P (SP), and somatostatin (SOM). SOM+ cells were more widespread than cells containing immunoreactivity (ir) to the other substances. Most reticular nuclei in frog brainstem contained ir to at least one of these chemicals. Cells with SOM ir were found in nucleus (n.) reticularis pontis oralis, n. reticularis magnocellularis, n. reticularis paragigantocellularis, n. reticularis dorsalis, the optic tectum, n. interpeduncularis, and n. solitarius. ENK-containing cell bodies were found in n. reticularis pontis oralis, n. reticularis dorsalis, the nucleus of the solitary tract, and the tectum. The midbrain contained most of the SP+ cells. Six nonreticular nuclei (griseum centrale rhombencephali, n. isthmi, n. profundus mesencephali, n. interpeduncularis, torus semicircularis laminaris, and the tectum) contained ir to one or more of the substances but did not project to the spinal cord. The descending tract of V, and the rubrospinal, reticulospinal, and solitary tracts contained all three peptides as did the n. profundus mesencephali, n. isthmi, and specific tectal layers. Because the distribution of neurochemicals within the frog brainstem is similar to that of amniotes, our results emphasize the large amount of conservation of structure, biochemistry, and possibly function that has occurred in the brainstem, and especially in the phylogenetically old reticular formation.     

面向产品变异设计的零件可拓物元模型研究

为满足产品变异设计的要求,提出了零件可拓物元模型结构.通过融合零件及其子结构的几何、结构关联关系、功能和语义等信息,建立了零件变异物元模型.结合可拓理论,研究了零件变异物元模型的可拓性,分析了零件变异物元模型对产品变异设计的支持情况.最后,基于零件变异物元模型,开发了产品变异设计原型系统,并以发动机曲轴零件为例,建立了零件可拓物元模型.实例证明,零件变异物元模型解决了产品变异设计引起的零件结构干涉和拓扑更新问题,为产品变异设计提供了条件.     

GC/MS法同时分析液体制剂及口服液型保健品中31种防腐剂和抗氧化剂

为满足药品监管需要,建立了气相色谱-质谱（GC/MS）联用方法测定以水、醇等液体为基质的药品及保健品中的防腐剂和抗氧化剂。采用选择离子监测（SIM）技术,同时检测滴眼液、注射液、滴剂、涂剂、口服液型保健品中的三氯叔丁胺、苯酚、苯甲醇、山梨酸、苯甲酸、2-甲基异噻唑啉酮、脱氢乙酸、乙氧基喹啉、己基间苯二酚、对羟基苯甲酸酯等28种防腐剂及TBHQ、BHA、BHT等3种抗氧化剂。结果显示,31种物质在0.005~1 mg/L范围内具有较好的线性关系,线性相关系数为0.998 5~0.999 9;在0.02～0.30 mg/L加标范围内,回收率为73.6%～109.9%,相对标准偏差（RSDs）为1.2%～13.6%;检出限（LODs,S/N ≥3）为0.001～0.008 mg/L,定量下限（LOQs,S/N ≥10）为0.003～0.020 mg/L。应用该方法进行了多个批次的实际样品分析,结果表明,此方法灵敏、准确、稳定、可靠,且应用范围广泛。     

铁碳合金相图的绘制

在分析铁碳合金相图特征的基础上,及说明相图中的特征点、线的含义的前提下,介绍了铁碳合金相图的画法,填写各区域的组织,从而完成整个铁碳合金相图的绘制.通过这种方式,能够较快地掌握铁碳合金相图的画法,理解相图中特征点、线及各区域组织的含义,对钢铁材料的选用和加工工艺的制订具有重要的理论和实践意义.     

The structure and function of auditory chordotonal organs in insects

Insects are capable of detecting a broad range of acoustic signals transmitted through air, water, or solids. Auditory sensory organs are morphologically diverse with respect to their body location, accessory structures, and number of sensilla, but remarkably uniform in that most are innervated by chordotonal organs. Chordotonal organs are structurally complex Type I mechanoreceptors that are distributed throughout the insect body and function to detect a wide range of mechanical stimuli, from gross motor movements to air-borne sounds. At present, little is known about how chordotonal organs in general function to convert mechanical stimuli to nerve impulses, and our limited understanding of this process represents one of the major challenges to the study of insect auditory systems today. This report reviews the literature on chordotonal organs innervating insect ears, with the broad intention of uncovering some common structural specializations of peripheral auditory systems, and identifying new avenues for research. A general overview of chordotonal organ ultrastructure is presented, followed by a summary of the current theories on mechanical coupling and transduction in monodynal, mononematic, Type 1 scolopidia, which characteristically innervate insect ears. Auditory organs of different insect taxa are reviewed, focusing primarily on tympanal organs, and with some consideration to Johnston's and subgenual organs. It is widely accepted that insect hearing organs evolved from pre-existing proprioceptive chordotonal organs. In addition to certain non-neural adaptations for hearing, such as tracheal expansion and cuticular thinning, the chordotonal organs themselves may have intrinsic specializations for sound reception and transduction, and these are discussed. In the future, an integrated approach, using traditional anatomical and physiological techniques in combination with new methodologies in immunohistochemistry, genetics, and biophysics, will assist in refining hypotheses on how chordotonal organs function, and, ultimately, lead to new insights into the peripheral mechanisms underlying hearing in insects.     

Future directions of fundamental research in additive tribochemistry

This paper reviews briefly the present state of fundamental research, in tribochemistry of load-carrying additives, including oiliness agents, organolsulphur, organochlorine, organophosphorus, organic borates and organometallic compounds. The emphasis is on the weak areas of investigation. It is revealed that the least understood mechanisms, such as the effect of additives on fretting wear, additive-material compatibility, the efficacy of antifatigue additives and the action of water-based fluid additives in metalworking, are the concern of overlapping spheres of learning. A cooperative effort by chemists, metallurgists and mechanical engineers would help overcome the difficulties posed by problems in areas beyond individual expertises. Some research projects for the future are also suggested.