4000吨/年硫磺回收装置真空带式过滤机技术改造

介绍了陕西延长石油集团延安石油化工厂硫磺回收装置真空带式过滤机从开工运行到实施技术改造前存在的问题,包括:机架和机座腐蚀问题,裙边的老化后产生的开裂、脱落问题,滤布的纠偏问题,控制系统问题,排水系统问题,现场通风问题,轴承座防腐问题,胶带防偏等问题,并进行了改造,改造后过滤机运行良好。     

玻璃幕墙玻璃的选用

玻璃幕墙的大量使用,随之而来的节能问题、光污染问题、安全防火问题等不容忽视,这些问题都与幕墙玻璃的选择有直接关系,换句话说玻璃幕墙问题的关键主要是玻璃的选择。     

书与画浅谈

中国画绵延了千年的安宁和辉煌来到现在,渐渐出现了众多的问题。出现这些问题的起因,或者说是这些问题的主因,其实是中国画的所谓当代化的问题。中国画的前世顺理成章了,中国画的今生呢?似乎谁都觉得出现了问题。那么中国画,或者说中国艺术,是否也是一个当代化的问题呢?作为特立的中国     

浅析煤气化工艺节能减排技术及应用

煤气化工艺节能减排问题是制约其发展的瓶颈,目前虽然取得了一定的发展,但是仍然存在较多的问题,包括能量利用问题、积灰问题、污水问题等等。目前发展了火炬系统伴烧介质的解决技术、煤气化洗涤循环水处理技术、合成气冷却器积灰问题的解决技术,在一定程度上解决了部分煤气化工艺的节能减排问题,但仍有很大的提升空间。     

管件采购“五统一”模式

管件采购工作,是物资供应采购工作中的一个普通采购行为,表面上看非常平常,但实际工作中,标准问题、生产工艺问题、图纸确认问题、母板采购方式和质量控制问题、配送问题、设计变更等问题,始终困扰着采购部门。     

“问题导向”提高本科生化工原理实验训练和工程能力

按照《化工原理实验》教学目的,基于"问题导向"理念,通过建立启发问题库形成"以学生为中心"的启发式教学法,引导学生发现问题、提出问题、分析问题和解决问题,促进学生进行自主实验训练,达到更好理解化工原理课程的原理,提升解决复杂工程问题能力的目的。     

装配式建筑生产施工质量问题与改进举措研究

装配式建筑作为一种高效且可持续的建筑方法,在建筑行业中不断崭露头角。然而,在其生产施工过程中仍然存在着一系列质量问题,这些问题直接影响到建筑项目的质量、性能和安全性。笔者通过探讨装配式建筑生产施工中常见的质量问题,如设计不一致性、设计变更和沟通问题、原材料质量控制问题、制造工艺问题、运输损伤问题、装配不准确问题以及施工标准执行问题,并提出改进举措,以确保装配式建筑项目的质量和可持续性。     

刍议数控机床故障判断与维护

数控技术是用数字信心对机械运动和工作过程控制的技术。数控技术的应用不但给传统制造业带来了革命性的变化,更使制造业成为工业化的象征。数控机床故障产生的原因是多种多样的,有机械问题、数控系统的问题、传感元件的问题、驱动元件的问题、强电部分的问题、线路连接的问题等。在面对数控机床故障和维修问题时,首先要防患于未燃,不能在数控机床出现问题后才去解决问题,要做好日常的维护工作和了解机床本身的结构和工作原理,这样才能做到有的放矢。     

管道安装施工管理常见问题及处理思考

石油天然气管道安装中,涉及到的问题方方面面,主要包括环境限制问题、工程地的状况问题、材料要求及质量问题、施工技术问题等,这些问题要求在工作中要有丰富的工作经验,仅凭书本上的知识及工程中的设计要点是很难解决的。一旦出现问题,而又不能及时解决,那么就很难保障工程质量,严重影响以后工程的质量,为此,我们要严格控制、管理施工过程中的每一个细节,保质保量的完成项目中的每一个环节。本文结合施工中的实际情况,总结出了常见的问题并提出了相应的解决办法。     

SGA与无线传感器网络QoS路由问题具体应用

无线传感器网络QoS路由问题是NP完全问题,遗传算法对求解该类问题比较有效。本文在基本遗传算法基础上,应用于无线传感器网络QoS路由具体问题。通过具体问题的应用,得出最优路由。     

DIMBOA Glucoside, a Wheat Chemical Defense, Affects Host Acceptance and Suitability of Sitobion avenae to the Cereal Aphid Parasitoid Aphidius rhopalosiphi

The influence of hydroxamic acids (Hx), plant secondary metabolites associated with aphid resistance in wheat, on the host acceptance and suitability of the aphid Sitobion avenae to the cereal aphid parasitoid Aphidius rhopalosiphi was evaluated. Aphids showed a reduction in mean relative growth rate and in body size in the wheat cultivar with higher Hx level. Reduction in aphid size was related to a decreased success in avoiding parasitoid oviposition. A minor increase in A. rhopalosiphi developmental time was observed in aphids feeding on the higher Hx cultivar. Experiments with different concentrations of DIMBOA glucoside, the main Hx in wheat, in artificial diets showed an increase in parasitoid developmental time at the highest concentration, with no change in other performance variables. The evidence is discussed in relation to the compatible utilization of host-plant resistance and biological control in integrated pest management.     

Influence of water immersion on the single-lap shear strength of aluminum joints bonded with aluminum-powder-filled epoxy adhesive

Durability of adhesively-bonded aluminum joints was investigated by measuring the joint strength using the single-lap shear test before and after exposure to distilled water and seawater. Fractured specimens were examined by photography and scanning electron microscopy to determine the failure modes. Addition of Al particles as much as 50 wt% did not cause any significant decrease in adhesive joint strength. Moreover, varying the Al filler content in the adhesive did not have a significant effect on adhesive behavior in either of the two environments studied. The unexposed adhesive joints failed almost completely in a cohesive (in the adhesive) failure mode. Some decrease in strength was observed in adhesive joints after exposure to both distilled water and seawater for 6 months. The decrease in adhesive joint strength was more significant for specimens immersed in distilled water than those immersed in seawater, probably due to the higher amount of moisture in the adhesive in distilled water than in seawater, as observed in a related moisture diffusion study. The joints exposed to distilled water or sea water failed in more than one mode. The interior part of the adhesive lap area failed in a cohesive mode while an adhesion failure mode was observed near the edges of the adhesive lap area, which is believed to be a result of moisture diffusion through the edges.     

Theanine,Antistress Amino Acid in Tea Leaves,Causes Hippocampal Metabolic Changes and Antidepressant Effects in Stress-Loaded Mice

By comprehensively measuring changes in metabolites in the hippocampus of stress-loaded mice, we investigated the reasons for stress vulnerability and the effect of theanine, i.e., an abundant amino acid in tea leaves, on the metabolism. Stress sensitivity was higher in senescence-accelerated mouse prone 10 (SAMP10) mice than in normal ddY mice when these mice were loaded with stress on the basis of territorial consciousness in males. Group housing was used as the low-stress condition reference. Among the statistically altered metabolites, depression-related kynurenine and excitability-related histamine were significantly higher in SAMP10 mice than in ddY mice. In contrast, carnosine, which has antidepressant-like activity, and ornithine, which has antistress effects, were significantly lower in SAMP10 mice than in ddY mice. The ingestion of theanine, an excellent antistress amino acid, modulated the levels of kynurenine, histamine, and carnosine only in the stress-loaded SAMP10 mice and not in the group-housing mice. Depression-like behavior was suppressed in mice that had ingested theanine only under stress loading. Taken together, changes in these metabolites, such as kynurenine, histamine, carnosine, and ornithine, were suggested to be associated with the stress vulnerability and depression-like behavior of stressed SAMP10 mice. It was also shown that theanine action appears in the metabolism of mice only under stress loading.     

Secondary Plant Products Causing Photosensitization in Grazing Herbivores: Their Structure,Activity and Regulation

Photosensitivity in animals is defined as a severe dermatitis that results from a heightened reactivity of skin cells and associated dermal tissues upon their exposure to sunlight, following ingestion or contact with UV reactive secondary plant products. Photosensitivity occurs in animal cells as a reaction that is mediated by a light absorbing molecule, specifically in this case a plant-produced metabolite that is heterocyclic or polyphenolic. In sensitive animals, this reaction is most severe in non-pigmented skin which has the least protection from UV or visible light exposure. Photosensitization in a biological system such as the epidermis is an oxidative or other chemical change in a molecule in response to light-induced excitation of endogenous or exogenously-delivered molecules within the tissue. Photo-oxidation can also occur in the plant itself, resulting in the generation of reactive oxygen species, free radical damage and eventual DNA degradation. Similar cellular changes occur in affected herbivores and are associated with an accumulation of photodynamic molecules in the affected dermal tissues or circulatory system of the herbivore. Recent advances in our ability to identify and detect secondary products at trace levels in the plant and surrounding environment, or in organisms that ingest plants, have provided additional evidence for the role of secondary metabolites in photosensitization of grazing herbivores. This review outlines the role of unique secondary products produced by higher plants in the animal photosensitization process, describes their chemistry and localization in the plant as well as impacts of the environment upon their production, discusses their direct and indirect effects on associated animal systems and presents several examples of well-characterized plant photosensitization in animal systems.     

2001年世界化学工业

2 0 0 1年世界经济增长减缓 ,下半年更是陷入困境。全球化工生产总产值为 1 5 650亿欧元 ,比 2 0 0 0年下降 0 4% ,美国、欧盟、日本的化工总产值分别占整个化工产业比重的 30 42 %、31 1 8%、1 5 1 4 %。美国化工及相关产品生产比上年下降0 7% ,加拿大也出现下降 ;日本下降 3 1 % (不包括医药 ) ;而西欧的增长率从 2 0 0 0年的 4 6 %减少为 1 1 % ;俄罗斯增加了 8% ,高于工业总体增长水平 ;东欧的生产与出口都保持增长 ,而亚洲则面临困难。     

GAS MIXING IN SLUGGING AND TURBULENT FLUIDIZED BEDS

The gas phase mixing in a fluidized bed of glass beads (d_p = 0.362 mm) in the slugging and turbulent flow regimes has been studied in a 0.1 m-ID × 3.0 m high Plexiglas column.

The gas dispersion in the downstream of the bed has been described by a diffusion process with the axial and radial dispersion coefficients. The radial dispersion coefficient of the gas phase is nearly constant with the variation of gas velocity in the slugging flow regime, but it increases with an increase in gas velocity in the turbulent flow regime.

Appreciable backmixing of the gas phase is pronounced in the slugging flow regime whereas the lower gas backmixing is produced in the turbulent flow regime. The gas backmixing coefficient increases with an increase in gas velocity in the slugging flow regime, but it decreases slightly with an increase in gas velocity in the turbulent flow regime.

The radial mixing and backmixing coefficients of the gas in terms of Peclet numbers have been correlated with the relevant dimensionless parameters (U_g/U_mf, p_s/p_g, d_p/D_t).

The gas flow pattern in the bed has been well represented by a simplified model based on the two gas phases in the dilute and dense phases which are percolating through the bed in plug flow. The present model can predict the gas exchange coefficient between the phases, the fractions of the dilute phase, the interstitial gas in the dense phase, and the interstitial gas velocity in the bed.     

Possible Role of Crystal-Bearing Cells in Tomato Fertility and Formation of Seedless Fruits

Crystal-bearing cells or idioblasts, which deposit calcium oxalate, are located in various tissues and organs of many plant species. The functional significance of their formation is currently unclear. Idioblasts in the leaf parenchyma and the development of crystal-bearing cells in the anther tissues of transgenic tomato plants (Solanum lycopersicon L.), expressing the heterologous FeSOD gene and which showed a decrease in fertility, were studied by transmission and scanning electron microscopy. The amount of calcium oxalate crystals was found to increase significantly in the transgenic plants compared to the wild type (WT) ones in idioblasts and crystal-bearing cells of the upper part of the anther. At the same time, changes in the size and shape of the crystals and their location in anther organs were noted. It seems that the interruption in the break of the anther stomium in transgenic plants was associated with the formation and cell death regulation of a specialized group of crystal-bearing cells. This disturbance caused an increase in the pool of these cells and their localization in the upper part of the anther, where rupture is initiated. Perturbations were also noted in the lower part of the anther in transgenic plants, where the amount of calcium oxalate crystals in crystal-bearing cells was reduced that was accompanied by disturbances in the morphology of pollen grains. Thus, the induction of the formation of crystal-bearing cells and calcium oxalate crystals can have multidirectional effects, contributing to the regulation of oxalate metabolism in the generative and vegetative organs and preventing fertility when the ROS balance changes, in particular, during oxidative stresses accompanying most abiotic and biotic environmental factors.     

Effects of Tyrosine and Tryptophan Supplements on the Vital Indicators in Mice Differently Prone to Diet-Induced Obesity

We studied the effects of the addition of large neutral amino acids, such as tyrosine (Tyr) and tryptophan (Trp), in mice DBA/2J and tetrahybrid mice DBCB receiving a high-fat, high-carbohydrate diet (HFCD) for 65 days. The locomotor activity, anxiety, muscle tone, mass of internal organs, liver morphology, adipokines, cytokines, and biochemical indices of animals were assessed. The Tyr supplementation potentiated increased anxiety in EPM and contributed to a muscle tone increase, a decrease in the AST/ALT ratio, and an increase in protein anabolism in both mice strains. Tyr contributed to a decrease in liver fatty degeneration and ALT reduction only in DBCB that were sensitive to the development of obesity. The addition of Trp caused an increase in muscle tone and potentiated an increase in anxiety with age in animals of both genotypes. Trp had toxic effects on the livers of mice, which was manifested in increased fatty degeneration in DBCB, edema, and the appearance of micronuclei in DBA/2J. The main identified effects of Tyr on mice are considered in the light of its modulating effect on the dopamine neurotransmitter metabolism, while for the Trp supplement, effects were presumably associated with the synthesis of its toxic metabolites by representatives of the intestinal microflora.     

LXR Agonist Increases the Lymph HDL Transport in Rats by Promoting Reciprocally Intestinal ABCA1 and apo A-I mRNA Levels

Liver and intestine are major sites of apo A-I synthesis in mammals. ABCAI is reported to be involved in the secretion of nascent HDL from cultured intestinal cells. However, whether ABCA1 participates in the secretion of nascent HDL from the intestine has not been assessed directly in vivo. This study examined the effect of a synthetic LXR-agonist “TO” on the lymphatic transport of HDL in thoracic duct-cannulated rats. The feeding of a TO-containing diet resulted in an increased transport of cholesterol and apo A-I in the lymph d > 1.063 g/ml lipoprotein fraction than did the feeding of a control diet without TO. The transport of cholesterol in whole lymph was lower, whereas the transport of apo A-I was higher, in the TO group. The abundance of mRNAs for ABCAI and apo A-I in the intestine was increased in the TO group. Furthermore, although the TO-containing diet reportedly increased the serum HDL concentration in intact mice and rats, no such effect was observed in the cannulated rats. The LXR agonist stimulated in vivo the synthesis of nascent HDL by increasing reciprocally the mRNA for ABCAI and apo A-I in the intestine, thereby contributing to an increase in the circulating HDL.     

Stress Distribution in Single Lap Joints with a Cracked Composite Adherend—Part II: Laminated Adherends

The effect of a crack in the overlap region of an adhesive single lap joint is studied on the shear stress distribution in adhesive layer. Each adherend is considered to be a laminated composite material with unidirectional fibers aligned in the direction of the applied load. Crack location is selected to be in the top adherend laminate, in the form of cut fibers and matrix bays. The crack can occur in any layer. The shear-lag model is used to derive the equilibrium equations which are then solved by means of eigenvector expansion. The effects of adhesive thickness, crack size, and location in the adherend, total number of layers in each adherends, volume fraction of fibers, and type of fibers are investigated on the shear distribution in the adhesive as well as load distribution in the intact fiber at the crack tip located in the top adherend. The effect of dissimilar laminated adherends is also investigated on the adhesive shear stress distribution. According to the results, in the presence of a crack, the peak shear stress in the adhesive layer and load concentration in the fibers are very susceptible to the adhesive thickness and number of layers in laminated adherends.