Experimental studies of the effects of atmospheric pollutants]

Experimental studies in man are an indispensable complement to epidemiological studies and experimental studies on animals. They aim at understanding the mechanisms of action of the main pollutants and at knowing their thresholds of triggering of the acute effects on the respiratory system. The studies made in man involve controlled exposure to different atmospheric pollutants, with measurement of the functional respiratory repercussions, studies of modification of the cells in broncho-alveolar lavage, as well as experimental protocols that combine inhalation of allergen and exposure to atmospheric pollutants by allergic subjects. The main results that are available are reported to distinguish those from normal subjects and those who are allergic. More recent protocols are based on exposure to concentrations that are close to atmospheric concentrations or those that are met in work places. The main data in the literature are reported in this journal and concern SO2 acid aerosols, dioxides of nitrogen, ozone and diesel particles. Pathogenic hypotheses concerning the undesirable effects of atmospheric pollutants on the respiratory system are considered.     

Influence of Alloying and Heat Treatment on the Abrasive and Impact–Abrasive Wear Resistance of High-Manganese Steel

The basic factors that affect the wear resistance of high-manganese steel are considered. The literature on this topic is reviewed. Conclusions are formulated regarding the materials used in existing studies. Research topics of interest to enterprises that manufacture and employ Hadfield steel are identified. Materials used in the machining of liquid steel are considered. Production technology for experimental high-manganese steel parts is discussed. The composition of the alloy employed as the base is analyzed. The procedure and equipment used to determine the cooling rate of alloys in the mold and to study the wear resistance in conditions of abrasive and impact–abrasive wear are outlined, as well as methods of thermal analysis. Results are presented for the alloying of Hadfield steel by nitrided ferroalloys and other alloys. The coefficients of abrasive and impact–abrasive wear resistance are plotted for different alloying conditions. In addition, the influence of the alloying elements on the wear resistance of high-manganese steel in different wear conditions is studied. The concentrations of the alloying elements corresponding to maximum abrasive and impact–abrasive wear resistance are established. In addition, the results of thermal analysis are presented. The heating of Hadfield steel castings prior to quenching is considered. The temperature ranges corresponding to processes such as excess-phase deposition, the solution of cementite in austenite, and complete solution of phosphide eutectic and metal carbides are established. The temperature limits of oxidation and decarburization of the steel are also determined. On the basis of the results, recommendations are made with a view to increasing the wear resistance of castings made from high-manganese steel for different operating conditions and also to selecting the heat-treatment temperature for such castings.     

The urographic signs of acute on chronic obstruction of the kidney

The signs of acute obstruction of the kidney and of chronic obstruction are well recognised and the combination of these signs enables a group of patients with acute-on-chronic obstruction to be recognised. The signs of acute obstruction are entirely nephrographic. They are manifested by an increasingly dense nephrogram, which may become striated, followed by an anatomically normal pyelogram. The signs of chronic obstruction are both pyelographic and nephrographic. The pyelographic signs are a dilated pelvicalyceal system. The nephrographic signs are a normal or low density nephrogram. Crescents may appear; these are due to opacification of the distorted medulla which retains its ability to concentrate the urine. In acute-on-chronic obstruction the signs of both conditions are present. Thus there is an increasingly dense nephrogram with a negative pyelogram. Crescents may appear. There is a slow flow in the dilated pelvicalyceal system.     

Some features of the ultrastructure of the coenecium of Rhabdopleura compacta

The coenecium of Rhabdopleura consists of a series of tubes, some erect and some repent. These tubes are composed of rings, one stacked within another. The rings are smooth on the inside surface and rough outside. Newly laid down rings are thin and smooth on both surfaces, fibrous material is laid down on the external surface during growth in thickness by the cephalic shield of the zooid. The erect tubes remain discrete, but the repent tubes, which are attached to the substratum can become incorporated in a mass of secreted material. The external vertical fibres cross several rings and probably serve to anchor the stack. Besides these fibrils that run for several segments, there are other shorter fibres that run along the length of each cylindrical ring, and are not continuous across the rings. These long and short fibres have features in common with those found in the graptolites.     

铁水包双枪脱硫的理论与实践

从铁水脱硫热力学及动力学出发,结合宝钢铁水脱硫的具体工艺,阐述了采用镁基脱硫剂进行铁水脱硫的方法及铁水脱硫工艺过程中的关键问题,其中喷吹流量、枪位、枪的形式、温度等工艺参数对脱硫效率有重要影响,提出了铁水脱硫过程中经常出现的问题,并给出解决这些问题的具体方法及措施.喷入的金属镁中只有一部分直接用于脱硫,大部分由于溶解于铁水中、氧化和气化等而损失掉,同时被氧化的这部分镁在铁水脱硫后形成MgO,恶化脱硫渣,造成脱硫渣的板结.     

添加剂对阴极铜质量的影响

介绍了铜电解精炼过程中骨胶、硫脲和盐酸三种添加剂的作用机理,研究了工业条件下骨胶、硫脲和盐酸三种添加剂以不同配比添加时对阴极沉积物的影响,从阴极铜的金相结构、韧性和化学成分进行分析,探索添加剂对阴极铜质量的影响。     

Role of the silicate phase of an enclosing rock in the prereduction of disseminated chromium ores

The composition and distribution of the products of solid-phase metal reduction from disseminated chromium ores are studied. Reduction is shown to occur in these ores despite the presence of isolating layers, which are made from the silicate phase of the enclosing ore, between a reducer and an ore grain. The channels of rapid reduction propagation inside ore grains are cracks filled with silicates. The propagation of reduction through the silicate phases is caused by favorable (as compared to chromospinellides) conditions for the motion of charged oxygen vacancies and oxygen, since these phases are in a glass state at the reduction temperature. The absence of boundaries and lattice defects in the glass state decreases the concentration of dislocation barriers. The low concentration of reducible cations in the silicates causes their motion to vacancy sinks, where reduced metals are accumulated.     

Engineering of Architectural Systems

Different aspects of architectural systems are discussed in this study. The definitions of architectural systems and their importance to the building community are presented. The functions of architectural systems are subdivided into primary and integrated functions. The analysis and design of architectural systems for both primary and secondary functions are explained. The applications of the recently popular concepts of performance-based engineering and multihazard considerations to architectural systems are discussed. Finally, the need for design guides for architectural systems is reasoned.     

半干法烧结烟气脱硫灰渣的资源化利用

阐述了半干法烧结烟气脱硫灰渣的成分与特点,分析了影响脱硫灰渣利用的主要因素,介绍了国内外脱硫灰渣的利用现状和资源化利用技术,提出了减少脱硫灰渣生成量的措施。     

On the practice of dichotomization of quantitative variables.

The authors examine the practice of dichotomization of quantitative measures, wherein relationships among variables are examined after 1 or more variables have been converted to dichotomous variables by splitting the sample at some point on the scale(s) of measurement. A common form of dichotomization is the median split, where the independent variable is split at the median to form high and low groups, which are then compared with respect to their means on the dependent variable. The consequences of dichotomization for measurement and statistical analyses are illustrated and discussed. The use of dichotomization in practice is described, and justifications that are offered for such usage are examined. The authors present the case that dichotomization is rarely defensible and often will yield misleading results. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Structural characteristics of the axons of nerve cells of the cat motor cortex

The axons of both pyramid and stellate neurons have a great number of ramifying collaterals which are considered in a comparative aspect. The both types of nerve cells are characterized by almost similar systems of the branching of axons, types of collaterals and end structures. The neurons are distinguished due to progressive development of one features of the axon structure and to a certain reduction of the others. In extreme forms the stellate cells have a well developed pericellular network, not coming outside the limits of the branching of their dendrites, while the pyramid cells are characterized by the mighty development of the main trunk and the absence of recurrent collaterals. Between these forms there are transitional forms.     

Numerical Simulations of Dynamic Instability of Elastic-Plastic Beams

This paper numerically investigates the dynamic instability of different elastic-plastic beams subjected to transverse pulse load. Two types of beam dynamic instability, i.e., symmetrical and asymmetrical instabilities, are studied. The unstable responses of the elastic-plastic beams are illustrated by investigating the modal participation factors of the lowest nine vibration modes, which are determined by inverse derivation of the numerically simulated beam deflection response. The critical pulse loads for the beam symmetrical and asymmetrical instabilities are obtained with respect to different load durations. Characteristic diagrams for beams with different boundary conditions and subjected to different type pulse loads are given. The present study conforms that not only axial compressive load induces instability of slender members, but also transverse pulse load results in instability of elastic-plastic beams.     

A comparison of current measures of the accuracy of feeling-of-knowing predictions.

Discusses 8 quantitative measures of feeling-of-knowing accuracy that have been used in the literature. The 3 measures considered at length are J. T. Hart's (see record 1965-13971-001) difference score, L. A. Goodman and W. H. Kruskal's (1954) gamma correlation, and the phi correlation. Quantitative relations between these measures are reported, as are connections with some basic axioms and a probabilistic conception of feeling-of-knowing accuracy. The currently most popular measure, the Hart difference score, has serious shortcomings. The Goodman-Kruskal gamma seems to be best. The remaining measures are inappropriate for the available feeling-of-knowing data for a variety of reasons. Also discussed are the implications of these results for other situations in which ordered 2?×?2 tables are examined to determine the relationship between predictions and criterion performance. (60 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Antibiotic susceptibilities of mycoplasmas and treatment of mycoplasmal infections

Mycoplasmas are the smallest free-living microorganisms, being about 300 nm in diameter. They are bounded by a triple-layered membrane and, unlike conventional bacteria, do not have a rigid cell wall. Hence, they are not susceptible to penicillins and other antibiotics that act on this structure. They are, however, susceptible to a variety of other broad-spectrum antibiotics, most of which only inhibit their multiplication and do not kill them. The tetracyclines have always been in the forefront of antibiotic usage, particularly for genital tract infections, but macrolides are also widely used for respiratory tract infections. Indeed, in comparison with the tetracyclines, erythromycin, the newer macrolides, the ketolides and the newer quinolones have equal or sometimes greater activity. The two latter antibiotic groups also have some cidal activity. The antibiotic susceptibility profiles of several mycoplasmas of human origin are presented, those of Mycoplasma pneumoniae and Mycoplasma genitalium being similar. Apart from the penicillins, mycoplasmas are innately resistant to some other antibiotics, for example the rifampicins. In addition, some may develop resistance, either by gene mutation or by acquisition of a resistance gene, to antibiotics to which they are usually sensitive. Resistance of mycoplasmas to tetracyclines is common and due to acquisition of the tetM gene. The antibiotic susceptibility pattern may be influenced greatly by the source of the mycoplasma; for example, one recovered from a contaminated eukaryotic cell culture that has been subjected to extensive antibiotic treatment may have an antibiotic profile quite different from the same mycoplasmal species that has been recovered directly from a human or animal source. Mycoplasmas may be difficult to eradicate from human or animal hosts or from cell cultures by antibiotic treatment because of resistance to the antibiotic, or because it lacks cidal activity, or because there is invasion of eukaryotic cells by some mycoplasmas. Eradication may be particularly difficult in immunosuppressed or immunodeficient individuals, particularly those who are hypogammaglobulinaemic. The regimes that are most likely to be effective in the treatment of respiratory or genitourinary mycoplasmal infections are presented.     

露采生产工程岩体裂缝类型与危害控制

归纳总结了紫金山金矿开采方式由地下转为露天开采后工程岩体的裂缝类型,分析了裂缝给露采工程岩体及矿山生产带来的危害,提出了露采工程岩体裂缝危害的控制措施。     

Reliability Analysis of Plank Decks

The objective of this study is to summarize the load and resistance criteria for highway bridge plank decks, and to estimate the reliability of plank decks designed by the AASHTO Code. Both transverse and longitudinal planks for a variety of typical stringer spacings and plank sizes are considered. Truck traffic load data are based on the model used to calibrate the 1994 AASHTO LRFD Code. However, for plank decks, wheel load rather than whole vehicle weight is most important, and these statistics are developed for this study. For wood planks, dead load and dynamic load are not significant. The limit state considered is flexural strength, and resistance statistics are presented for wood planks in terms of modulus of rupture. Special flat-wise use data are presented to account for section aspect ratio as well as edge of load application. The reliability analysis is carried out using the procedure developed for calibration of AASHTO LRFD. Reliability indices for both the AASHTO Standard and AASHTO LRFD Code are presented for plank decks. The results indicate that there are considerable differences in plank reliability indices. Causes of inconsistencies in safety are identified.     

冷却模式对铸坯表面组织的影响

 制作直径10mm的试样以模拟铸坯表面组织,将试样分别在传统冷却模式下和控制冷却模式下进行冷却,通过对试样截面的微观组织形貌进行金相分析,从而研究冷却模式对铸坯表层组织结构的影响。试验得到如下结果：传统冷却条件下,试样边部为块状铁素体和珠光体,晶粒尺寸在10~200μm之间,中心位置为条状、针状铁素体和珠光体,晶粒粗大,组织不均。控制冷却条件下,试样均由块状铁素体和珠光体组成,晶粒尺寸在9.36~12.25μm之间,晶粒细小,组织均匀。控制冷却可以通过细化晶粒来提高铸坯表面的高温塑性从而对避免表面横裂纹的发生产生有利影响。     

Machining of Machine Elements Made of Polymer Composite Materials

The machining of the machine elements that are made of polymer composite materials (PCMs) or are repaired using them is considered. Turning, milling, and drilling are shown to be most widely used among all methods of cutting PCMs. Cutting conditions for the machining of PCMs are presented. The factors that most strongly affect the roughness parameters and the accuracy of cutting PCMs are considered.     

Evaluation of Seismic Performance of Gravity Load Designed Reinforced Concrete Frames

The seismic performance of reinforced concrete frames designed for gravity loads is evaluated experimentally using a shake table. Two 1:3 scale models of one-bay, three-storied space frames, one without infill and the other with a brick masonry infill in the first and second floors, are tested under excitation equivalent to the spectrum given in IS 1893-2002. From the measured response of the models during excitation, the shear force, interstory drift, and stiffness are evaluated. The effect of masonry infill on the seismic performance of reinforced concrete frames is also investigated. Then, the frames are tested to failure. Severe damage is observed in the columns in the ground floor. The damaged columns are strengthened by a reinforced concrete jacket. The frames are again tested under the same earthquake excitations. The test results showed that the retrofitted frames could sustain low to medium seismic forces due to a significant increase in strength and stiffness.