Peroxisomes of the firefly lantern

For the estimation and correction of errors in the measurement of the respiratory flow with viscosity-affected respiratory flow receptors the viscosity of natural respiratory gases (N2, O2, CO2, H2O) and of the ternary system helium-oxygen-nitrogen, which is of importance in pulmonary function diagnosis, was determined. Corresponding density values were calculated. Allowance was made for such special features of spirometry as exchange of O2 for CO2 and water vapour saturation at 37 degrees C. The viscosity of the ternary system is shown in a graph. The formulae indicated have been simplified as far as this was compatible with the demands of accuracy. The fluctuations in density and viscosity of natural respiratory gases can be read directly from a table.     

Fracture characteristics of acrylic bone cements. I. Fracture toughness

The vital first phase of the overall materials study to protract the life of the total joint replacements is the identification of the fracture toughness and fatigue properties of bone cements. Information gained from fatigue testing, performed in a manner which simmulates in vivo conditions, and fracture toughness, which is a measure of the propensity of a crack to propagate, is the first step towards the prediction of the life of the total joint replacement. This study is concerned with the fracture toughness of Zimmer and Simplex-P cold-curing bone cements. Following cement fabrication conditions which closely approximate clinical procedures, fracture toughness testing was conducted on cement specimens which were immersed in bovine serum at 37 degrees C in order to simulate in vivo conditions. In addition, a similar study was completed on specimens, tested in air at ambient temperature for purposes of comparison. Results of this procedure, when analyzed by a Student's t-test at the 95% confidence level with eight degrees of freedom, indicate that both Zimmer and Simplex-P exhibit a higher fracture toughness in the simulated physiological environment. In order to determine whether the addition of barium sulfate to these cements compromises the fracture toughness, the above described testing rationale was repeated, indicating the existence of a complicated relationship between the different testing environments and barium sulfate. The importance of these results lies in the fact that an increased fracture toughness indicates that a cement will inherently exhibit a greater degree of resistance to the propagation of cracks, which could contribute to the ultimate failure of the total joint replacement.     

Morphological changes of the corpus callosum in schizophrenia

Asthma and allergic disorders have been on the increase in recent decades, especially among children living in affluent countries; some aspects of the "Western" way of life may explain this trend. We evaluated the relation of aeroallergen skin test reactivity with socioeconomic status, number of siblings, and respiratory infections in early life. We examined a total of 2,226 schoolchildren, ages 7-11 years, in three areas of Lazio, Italy. Skin prick tests were performed to assess atopic status, and self-administered questionnaires were completed by the parents. The prevalence of prick test positivity was greater among children whose fathers were in the highest educational level than among those in the lowest [prevalence ratio (PR) = 1.58; 95% confidence interval (CI) = 1.21-2.06]. There was also a lower prevalence of atopy among larger sibships (PR = 0.38 for subjects with four or more siblings vs those without siblings; 95% CI = 0.14-0.99). A history of bronchitis or bronchiolitis before age 2 years was weakly associated with an increased risk of atopy, whereas a history of pertussis or pneumonia was not. Both the effect of father's education and the influence of larger sibship size remained when we adjusted for several potential confounding factors, including respiratory infections in early life. We infer that higher socioeconomic status and lower sibling number are determinants of atopy in this Italian population. Protection arising from early severe respiratory infections does not explain this association, although we cannot exclude a role for other viral infections.     

The synthesis and evaluation of benzannelated-azatoxins: the benzazatoxins

The synthesis and evaluation of azatoxin congeners possessing annealed aromatic frameworks are described. The compounds were evaluated for their abilities to affect topoisomerase II inhibition through the stabilization of "cleavable complex" and for the inhibition of tubulin polymerization using purified bovine brain tubulin.     

Tendon force measurements and movement control: a review

Knowledge of the mechanical and electrical output from skeletal muscle is of interest to investigators from several disciplines including physiology, biomechanics, neuroscience, orthopedics, and physical rehabilitation. Estimates of muscle output (i.e., force) have generally been made using indirect calculations. Forward solution (e.g., EMG) and optimization models have recently been developed using a wide variety of input parameters to estimate force output of individual muscles. These estimates, however, have lacked comparison values necessary for validation. In vivo measurements of muscle force have been made in both animals and humans using a "buckle" type tendon transducer surgically implanted on the tendons of the muscles under study. Investigations utilizing these transducers have addressed a wide range of questions regarding muscle function. This review examines the use of this technology and discusses the significance of the future use of "buckle" transducers in studies exploring load sharing among muscles and in the validation of existing models that estimate muscle force.     

油田套管阴极保护技术的应用

油田套管腐蚀是油气开采过程中普遍存在的问题.套管一般深埋于地下,所处的地下环境较为复杂,阴极保护技术可使钢质套管得到保护,从而延长套管的使用寿命.通过一套完整的阴极保护系统技术设计,给出了完整的阴极保护施工方法.通过Beasy软件利用数值模拟技术计算不同阳极埋深对阴极保护电位分布的影响,评价了外加电流阴极保护对井底的保护效果.仿真结果表明:阳极安装在井组中间距离井组横向距离12 m,埋深为100 m,井组可得到良好保护.该技术防腐蚀效果明显,套管腐蚀现象得到显著改善,能满足不同条件下的防腐蚀需求,可在油田开展进一步推广应用.     

基于学科服务的高校智慧图书馆创建的策略

在智能技术不断发展的今天,人类社会已经步入智慧时代,高校图书馆也需要将智慧图书馆创建作为发展目标。首先阐述了高校智慧图书馆的发展现状与优势,然后就如何从学科服务出发创建高校智慧图书馆提出策略,包括整合信息资源、优化平台结构、加强挖掘力度、重视安全维护等。     

Biochemistry of coenzyme B12-dependent glycerol and diol dehydratases and organization of the encoding genes

Glycerol and diol dehydratases exhibit a subunit composition of alpha 2 beta 2 gamma 2 and contain coenzyme B12 in the base-on form. The dehydratase reaction proceeds via a radical mechanism. The dehydratases are subject to reaction inactivation by the substrate glycerol which is caused by a cessation of the catalytic cycle because coenzyme B12 is not regenerated, instead 5'-deoxyadenosine and a catalytically inactive cobalamin are formed. The genetic organization of the dehydratase genes is quite similar in all organisms. Downstream of the dehydratase genes an open reading frame encoding a polypeptide of approximately 600 amino acids was identified which is apparently involved in the reactivation of suicide-inactivated enzyme.