大型进口工程设备维修探讨

进口大型工程设备使用率和寿命很大程度上取决于维修质量的好坏。文章分析了我国进口大型设备仪器使用维修现状,有针对性地提出了一些维修办法,并立足国产化技术,对维修备件的国产化进行了有益的实践。     

Influence of Temperature on Glucose Utilization by Pseudomonas fluorescens

The influence of temperature on the conversion of glucose into cell material and into energy for maintenance was determined for Pseudomonas fluorescens by a steady-state turbidity method and by a substrate utilization method. Conversion of glucose into cell material was measured as yield; conversion of glucose into energy for maintenance was measured as specific maintenance, the minimum dilution rate in continuous culture below which a steady state is not possible. The values obtained by the two methods were nearly identical; with both, the yield and specific maintenance decreased with decreasing temperature. The specific maintenance consumption rate (milligrams of glucose taken up per milligram of cell dry weight per hour at zero growth) was also calculated by the substrate utilization method and found to decrease with decreasing temperature. However, the amount of glucose consumed per generation for maintenance increased with decreasing temperature. This increased glucose consumption for maintenance may provide a partial explanation for the decrease in yield at low temperatures. Small amounts of glucose were also converted into pigment at all temperatures tested, with the greatest amount formed at 20 C.     

The maintenance of linoleum and PVC floor coverings in sweden the significance of the usage phase in an LCA

Goal, Scope and Background  An extensive life cycle inventory of the maintenance of floor coverings has been carried out for the professional cleaning sector in Sweden. Different maintenance methods for linoleum and PVC were inventoried. The objective has been to develop a model for estimating the resource use in the Swedish professional floor cleaning and maintenance sector. Several important actors involved in the Swedish professional cleaning sector participated in the inventory. An agreement could be reached for a limited number of methods and products. The result can be regarded as representative for the maintenance of linoleum and PVC in respect to professional maintenance in Sweden. Methods, Results and Discussion  The maintenance was divided into two different types: periodical and frequent maintenance. It showed that 36 maintenance systems were relevant (each system is a combination of periodical and frequent maintenance) and that the expected impacts from maintenance could be found through an inventory of these 36 systems. The resource use for each system was inventoried and pertaining LCI data was collected. However, it showed that the resource use for the maintenance systems could not be quantified without estimating three so called ‘application-specific context parameters’, which were not depending on the maintenance system but related to the specific type of premises. The three parameters were: the frequency of the periodical maintenance (P); the frequency of the frequent maintenance (P), and; the estimated service life (L) of the floor covering. The prediction of a specific resource use for maintenance of a specific floor covering could thereby not be carried out without the knowledge of the three application-specific parameters. However, all collected data were supplied to a specifically developed calculation program, which made it possible to estimate the impact from the 36 maintenance systems for different choices of estimated service life and maintenance intervals for the periodical and frequent maintenance. Approximately 1300 different scenarios were provided, using different values for F, P and L, respectively, and compared in order to answer several questions of concern to the professional cleaning sector in Sweden. Conclusions  Some of the most important conclusions generated from the scenarios were: The impacts from maintenance proved to be significant compared to the impacts from the floor. In several cases, wax-based systems turned out to be preferable to polish systems. However, the result is sensitive to the chosen cleaning method. When polish systems are chosen, the choice of floor covering may influence the usage phase in a significant way. Recommendation and Outlook  A framework has been provided as a base for further development. Possibly, the data could be improved and supplied with data of other products and materials. Even other types of floor coverings may be considered. The focus has primarily been on energy use and emission of chemicals recorded as dry substance. It is desirable with a development of a method for quantitative assessment of the actual chemicals.     

数字减影血管造影设备的维护与维修

数字减影血管造影设备是大型医学影像仪器,在临床诊断及治疗发挥着重要的作用。因此,及时的维护和规范的保养是降低设备故障,减少维修成本,提高工作效率的关键。本文对我院数字减影血管造影设备的保养工作展开回顾,分析临床工作中常见的设备故障,并总结实用的维护、保养方法,为有效利用设备资源提供参考。     

Maximum likelihood estimation of growth yields

This work is concerned with statistical methods to estimate yield and maintenance parameters associated with microbial growth. For a given dilution rate, an experimenter typically measures substrate concentration, oxygen utilization rate, the rate of carbon dioxide evolution, and biomass concentration. These correlated response variables each contain information about the maintenance and yield parameters of interest. A maximum likelihood estimator which combines this correlated information for the yield and maintenance parameters is proposed, evaluated, and tested on literature data. Both point and interval estimators are considered.     

医疗设备软件维修与调整

介绍了医疗设备软件维修必须具备的知识,DSA机与培养仪软件维修实例。同时还介绍了医疗设备的调整的方法,用于排除故障的经验。     

On maintenance models in severely and long-term limited membrane bioreactor cultivations

Membrane bioreactors (MBRs) are combinations of common bioreactors and membrane separation units for biomass retention. Through increased biomass concentration, they allow increased productivity (or smaller reactor volume, respectively). Besides high biomass concentrations, operation at very low growth rates is typical for MBRs. In this regime, maintenance metabolism where substrate uptake only yields energy for cell survival becomes of higher importance than in processes run at higher growth rates. While thermodynamically based correlations for the prediction of maintenance coefficients are available for chemostat or other medium growth rate processes, some authors have mentioned a change in energy demand in MBRs and a dependence of maintenance parameters on operating conditions. Due to the fact that often mixed cultures are used and resulting from the different evaluation methods used by different authors, views on the possible influences on maintenance parameters differ. However, it is accepted that common models describing microbial growth and production of metabolites or degradation of pollutants do not consider the effects caused by severe limitations and therefore cannot sufficiently be applied to MBRs. In this study, maintenance parameters were determined for a model organism (Ustilago maydis) and results from different evaluation methods were compared. A continuous fit of respiration data gave more consistent results than the traditional method of plotting specific uptake versus growth rate. They suggest that below micro = 10% micro(max) the maintenance coefficient drops to a third of the value in short-term limited cultures.     

一种基于本体集成的生物医学数据库中语义映射维护方法研究

生物医学数据库到生物医学本体的语义映射是基于本体集成生物医学数据库系统的一个重要环节。而生物医学本体随着学科的发展不断演化,造成了集成系统不稳定。针对这个问题,本文在本体演化条件下,分析并发现了语义映射的变化规律,设计了对应的维护流程和维护方法,并通过计算维护收益率证明了该方法对映射的维护是有效性的,从而增强了集成系统在本体演化条件下的稳定性。     

Establishment and Management of Native Functional Groups in Restoration

The limiting similarity hypothesis predicts that communities should be more resistant to invasion by non‐natives when they include natives with a diversity of traits from more than one functional group. In restoration, planting natives with a diversity of traits may result in competition between natives of different functional groups and may influence the efficacy of different seeding and maintenance methods, potentially impacting native establishment. We compare initial establishment and first‐year performance of natives and the effectiveness of maintenance techniques in uniform versus mixed functional group plantings. We seeded ruderal herbaceous natives, longer‐lived shrubby natives, or a mixture of the two functional groups using drill‐ and hand‐seeding methods. Non‐natives were left undisturbed, removed by hand‐weeding and mowing, or treated with herbicide to test maintenance methods in a factorial design. Native functional groups had highest establishment, growth, and reproduction when planted alone, and hand‐seeding resulted in more natives as well as more of the most common invasive, Brassica nigra. Wick herbicide removed more non‐natives and resulted in greater reproduction of natives, while hand‐weeding and mowing increased native density. Our results point to the importance of considering competition among native functional groups as well as between natives and invasives in restoration. Interactions among functional groups, seeding methods, and maintenance techniques indicate restoration will be easier to implement when natives with different traits are planted separately.     

Toxoplasma gondii maintenance in tissue culture: a new efficient method for culturing RH tachyzoites

We describe here a new tissue culture method for prolonged laboratory maintenance of tachyzoites of the highly virulent RH strain of Toxoplasma gondii. Using a rapidly proliferating murine tumor cell line (YAC-1), the method described is easy to perform and is as or more efficient (both in terms of yield and cost) than other traditional methods for maintenance of the parasite. Furthermore, upon prolonged maintenance (greater than 160 days) in YAC-1 tissue culture, the pathogenicity of the parasite, as well as its capacity to elicit an immune response, are comparable to that of organisms maintained in mice. We conclude therefore, that the method described herein is a suitable alternative to the traditional method of maintenance of virulent RH strain T. gondii tachyzoites.     

Reproductive Potential of Patients Treated by Maintenance Haemodialysis

Three of the wives of 25 men undergoing maintenance haemodialysis for terminal renal failure became pregnant. This suggests that fertility is not necessarily impaired in these patients and that contraceptive methods should be used by women patients at risk.     

Estimation of survival distributions of treatment policies in two-stage randomization designs in clinical trials

Some clinical trials follow a design where patients are randomized to a primary therapy at entry followed by another randomization to maintenance therapy contingent upon disease remission. Ideally, analysis would allow different treatment policies, i.e., combinations of primary and maintenance therapy if specified up-front, to be compared. Standard practice is to conduct separate analyses for the primary and follow-up treatments, which does not address this issue directly. We propose consistent estimators for the survival distribution and mean restricted survival time for each treatment policy in such two-stage studies and derive large-sample properties. The methods are demonstrated on a leukemia clinical trial data set and through simulation.     

Strategies for prevention and control of nosocomial aspergillosis

Measures for prevention and control of nosocomial aspergillosis include the proper maintenance of air conditioning installations, cleaning of surfaces, adherence of personnel to recommendations on circulation, use of barrier methods and the proper isolation of selected areas, specially during construction work.     

一种基于本体集成的生物医学数据库中语义映射维护方法研究

生物医学数据库到生物医学本体的语义映射是基于本体集成生物医学数据库系统的一个重要环节.而生物医学本体随着学科的发展不断演化,造成了集成系统不稳定.针对这个问题,本文在本体演化条件下,分析并发现了语义映射的变化规律,设计了对应的维护流程和维护方法,并通过计算维护收益率证明了该方法对映射的维护是有效性的,从而增强了集成系统在本体演化条件下的稳定性.     

Design of reserve networks and the persistence of biodiversity

Sophisticated computational methods have been developed to help us to identify sets of nature reserves that maximize the representation of regional diversity, but, until recently, the methods have not dealt explicitly and directly with the main goal of reserve networks, that of the long-term maintenance of biodiversity. Furthermore, the successful application of current methods requires reliable information about species distributions, which is not always available. Recent results show that data quality, as well as the choice of surrogates for biodiversity, could be critical for successful reserve design. Because of these problems and a lack of communication between scientists and managers, the impact of computational site-selection tools in applied conservation planning has been minimal.     

Preservation of live cultures of basidiomycetes – Recent methods

Basidiomycetes are used in industrial processes, in basic or applied research, teaching, systematic and biodiversity studies. Efficient work with basidiomycete cultures requires their reliable source, which is ensured by their safe long-term storage. Repeated subculturing, frequently used for the preservation, is time-consuming, prone to contamination, and does not prevent genetic and physiological changes during long-term maintenance. Various storage methods have been developed in order to eliminate these disadvantages. Besides lyophilization (unsuitable for the majority of basidiomycetes), cryopreservation at low temperatures seems to be a very efficient way to attain this goal. Besides survival, another requirement for successful maintenance of fungal strains is the ability to preserve their features unchanged. An ideal method has not been created so far. Therefore it is highly desirable to develop new or improve the current preservation methods, combining advantages and eliminate disadvantages of individual techniques. Many reviews on preservation of microorganisms including basidiomycetes have been published, but the progress in the field requires an update. Although herbaria specimens of fungi (and of basidiomycetes in particular) are very important for taxonomic and especially typological studies, this review is limited to live fungal cultures.     

Intestinal subepithelial myofibroblasts support in vitro and in vivo growth of human small intestinal epithelium

The intestinal crypt-niche interaction is thought to be essential to the function, maintenance, and proliferation of progenitor stem cells found at the bases of intestinal crypts. These stem cells are constantly renewing the intestinal epithelium by sending differentiated cells from the base of the crypts of Lieberkühn to the villus tips where they slough off into the intestinal lumen. The intestinal niche consists of various cell types, extracellular matrix, and growth factors and surrounds the intestinal progenitor cells. There have recently been advances in the understanding of the interactions that regulate the behavior of the intestinal epithelium and there is great interest in methods for isolating and expanding viable intestinal epithelium. However, there is no method to maintain primary human small intestinal epithelium in culture over a prolonged period of time. Similarly no method has been published that describes isolation and support of human intestinal epithelium in an in vivo model. We describe a technique to isolate and maintain human small intestinal epithelium in vitro from surgical specimens. We also describe a novel method to maintain human intestinal epithelium subcutaneously in a mouse model for a prolonged period of time. Our methods require various growth factors and the intimate interaction between intestinal sub-epithelial myofibroblasts (ISEMFs) and the intestinal epithelial cells to support the epithelial in vitro and in vivo growth. Absence of these myofibroblasts precluded successful maintenance of epithelial cell formation and proliferation beyond just a few days, even in the presence of supportive growth factors. We believe that the methods described here can be used to explore the molecular basis of human intestinal stem cell support, maintenance, and growth.     

The treatment of Wilson's disease with zinc. IV. Efficacy monitoring using urine and plasma copper

Progress has been made in establishing the efficacy and safety of oral zinc as a maintenance therapy for Wilson's disease. It is important to develop simple, noninvasive monitoring methods to assure the adequacy of zinc therapy in individual patients. In this paper we report the use of 24-hr urine copper and plasma copper measurements to monitor efficacy of zinc maintenance therapy in 30 Wilson's disease patients. In examples of therapeutic inadequacy such as noncompliance, these values increase. With continued long-term adequate therapy, they remain stable or decrease. These two simple monitoring tools appear to be very useful in monitoring Wilson's disease patients receiving zinc therapy.     

The maintenance nitrogen requirement of the zebra finch Taeniopygia guttata

A procedure is described for the accurate determination of the maintenance nitrogen requirement (MNR) of small granivorous birds. When used with the zebra finch (Taeniopygia guttata), it yielded a MNR of 403 mg kgW(-0.75) d(-1). This is lower than most other passerines so far measured and more similar to some nonpasserine species. Similarly, the value for endogenous nitrogen loss estimated for the zebra finch (153 mg kgW(-0.75) d(-1)) is less than that for passerines in general but higher than the nonpasserine value. We suggest that the low MNR of the strictly granivorous zebra finch is primarily an adaptation to seed diets in which high-quality protein is a limiting factor. Comparison with a wider range of species reported in the literature was restricted because inappropriate methods have been used to estimate MNR in many cases, including the use of growing or reproducing birds and the assumption that maintenance of body mass necessarily coincides with maintenance of zero nitrogen balance.