Consideration of microbiology in modelling the near field of a L/ILW repository

Summary The long-term safety of proposed repositories for nuclear waste is demonstrated by the use of chains of mathematical models describing the performance of the various barriers to radionuclide mobilisation, transport, release into the biosphere and eventual uptake by man. Microbial contamination of such repositories is to be expected, and hence the extent and consequences of microbial activity must also be quantified. This paper describes a modelling approach to determine the maximum microbial activity in the near field of a repository, which can thus be related to maximum possible degradation of performance. The approach is illustrated by application to a proposed Swiss repository for low- and intermediate-level waste (L/ILW), which is immobilised in concrete and emplaced in a marl host rock.     

The Swedish final repository and the possible risk of interactions by microbial activities

Summary The final Swedish repository for low- and intermediate-level nuclear waste is described, and some of the possible problems caused by microbial activity during storage are discussed. Microbial degradation of bitumen constitutes one of the greatest risks in the silo part of a repository. The production of carbon dioxide due to both aerobic and anaerobic processes might lead to a decrease in the pH of the water, inducing corrosion of the metal construction and storage containers, with large amounts of hydrogen gas being produced. A risk assessment for the repository must thus take into account the various activities of microbes.     

Microbial degradation of bitumen

Summary A blown bitumen Mexphalte R 90/40 with a high content of saturated hydrocarbons was degraded by several microorganisms to the same extent. In batch cultures ofSaccharomycopsis lipolytica, maximal biodegradation was estimated to be about 9% w/w, 3.2·10^–3 g/cm² and 3.1·10^–3 cm of degraded bitumen. The Mexphalte R 90/40 degradation rate was closely coupled to biofilm formation. The microbial activity concerned predominantly the oxidation of saturated hydrocarbons. A direct distillation bitumen 80/100 with a low content of saturated hydrocarbons and a high content of aromatic hydrocarbons and resins was more resistant to biodegradation.     

The importance of microbiology in waste management

Until a hundred years ago, the waste products from human activities were returned into the environment and underwent the biosphere's natural elimination processes without there being any long-term charge on the environment. During the last century, the increase in the amount of refuse has been accompanied by a decrease in its quality, mainly due to the production and dispersal of heavy metals and xenobiotic compounds. Both useful and noxious microbial processes have been underestimated in applied research in the field of waste management which, until now, has dealt mainly with artificial technologies. This paper presents some examples of microbiological processes occurring in waste treatment, particularly dumping, waste incineration, composting and biomethanization.     

Modelling of microbial degradation processes: The behaviour ofmicroorganisms in a waste repository

Summary In a repository for radioactive disposal the waste material is kept in place by several shells and boundaries to prevent a long term recycling of the material into the environment. Present investigations on various chemical and biological processes can be extrapolated into future centuries only with great uncertainty. Models may therefore be a good tool to forecast processes which may occur within the repository and to estimate whether the barriers present will prevent the leaching of waste material within a given time span. A mathematical model is described based on an experimental laboratory setup, a microcosm described by West et al.^19–22 simulating in a laboratory system repository conditions for a Swiss L/ILW repository. It includes microbial as well as physico-chemical processes. These simulations indicate that biological processes such as gas formation or proton release should also be included into the safety assessment of the repositories.     

Biodegradation of bitumen used for nuclear waste disposal

Summary Studies have been carried out to test microbial degradation of bitumen used for encapsulating radioactive waste in Sweden. Microorganisms have been isolated that degrade bitumen. In ong-term tests under conditions simulating those in the silo part of the final repository for low-and intermediate-level radioactive waste, both aerobic and anaerobic degradation of bitumen has been found, equivalent to 0.6–1.5 moles CO₂/month·mg bitumen and 1.1–1.5 moles CO₂/month·mg bitumen, respectively.     

The importance of radioactivity in geoscience and mining

Almost simultaneously with Roentgen rays, natural radioactivity was discovered. Its investigation led to important fundamentals of the geosciences: petrophysics, terrestrial heat flow, isotope geology, and absolute geological chronology. In applied geophysics and geology, exploration of radioactive ores and of tectonic faults, and radiometric well loggings, are used. Production of radioactive water and mining for uranium ores are discussed, including their development (especially in the Saxon ore mountains) and the consequences on health (radon in underground air and houses). Disposal of radioactive waste is touched on briefly.     

Microbial influence on the sorption of137Cs onto materials relevant to the geological disposal of radioactive waste

Summary A major concern in the geological containment of radioactive wastes is the speed of movement of radionuclides from the repository, after their eventual leaching and release, into the geosphere and finally into the biosphere. Radionuclide sorption onto the host rock is an important retarding mechanism. Experimental evidence shows that the presence of microbes in this environment influences the sorption capabilities of the host rock. Their presence can decrease the amount of retardation of¹³⁷Cs, a common radionuclide in radioactive waste, by the solid phase. Sorption methods and data analysis procedures are presented and the implications for radioactive waste disposal assessments are discussed.     

三种方法测定碱性磷酸酶对肝疾病的诊断价值

目的研究血清碱性磷酸酶检测临床肝疾病时的方法学,提高临床诊断价值。方法收集临床不同肝疾病病人的血清,分别用3种方法测定其碱性磷酸酶的活性,并与健康对照组比较作诊断性能分析。结果各肝疾病组血清碱性磷酸酶的活性与对照组相比有极显著差异（P〈0．001）;3种方法分别测定各组之闻的血清碱性磷酸酶活性无显著性差异（P〉0．05）。2．乙基氨基乙醇、2-氨基-2-甲基-1-丙醇、二乙醇胺3种缓冲液测定试剂盒方法测定的灵敏度分别为55．20％、47．96％、51．13％,特异度分别为100％、100％、93．75％。结论血清碱性磷酸酶可以作为各类肝病的临床诊断指标;对肝疾病血清碱性磷酸酶测定用2,乙基氨基乙醇缓冲液的试剂方法测定效果较好。     

环境微生物的分子生物学研究方法

本文介绍了在环境微生物生态研究中的分子生物学方法如分子杂交,聚合链式扩增技术PC震,rRNA基因同源分析法,新型凝胶电泳技术,生物醌谱图法等和应用。这些技术的使用将大大扩展微生物生态学研究的空间,并使得在分子水平研究生态问题的机制成为可能。     

循环农业模式下的农业废弃物资源化利用

循环农业是以生态学、生态经济学与生态工程学原理及基本规律作为指导的农业经济形态,物质循环再生和资源减量是其重要特征之一。遵从循环农业中的生物多样性、生物与环境相互作用趋同趋异进化、食物链加、减环和种间竞争等生态学原理,是改善农村生态环境,提高农民生存质量,减少资源浪费,实现农业废物资源化利用和农业可持续发展的有效途径。     

我国工业固体废弃物的高技术研究进展

本文根据作者多年在工业废弃物方面的研究开发工作,论述了工业废弃物的现状,开发基础和高技术研究进展。     

The role of forecasting in corporate strategy: The xerox experience

This paper presents the system of analysis used by the Xerox Corporation to relate the external environment to company decisions. The system is sophisticated and elaborate, comes to grips with such issues as product forecasting, market monitoring, activity monitoring, materials and labour cost analysis, and product price analysis. In addition, the system examines the longer-term issues associated with corporate strategy, with the more recent initiatives directed toward the strategic focus The Xerox case illustrates very well how externally provided forecasts of economic environments, both at home and abroad, can be used as inputs to a variety of econometric products to serve the individual corporation. The challenge in this work is to build the bridges from the external forces to the critical company decisions. That is a task which requires sophisticated tools and skilled professionals to accomplish. This case study shows what can be done.     

The structure and function of platelet-activating factor acetylhydrolases

Platelet-activating factor acetylhydrolases (PAF-AHs, EC 3.1.1.47) constitute a unique and biologically important family of phospholipase A₂s. They are related to neither the well-characterized secretory nor cytosolic PLA₂s, and unlike them do not require Ca²⁺ for catalytic activity. The distinguishing property of PAF-AHs is their unique substrate specificity they act on the phospholipid platelet-activating factor (PAF), and in some cases on proinflammatory polar phospholipids, from which they remove a short acyl moiety – acetyl in the case of PAF – located at the sn-2 position. Because PAF is found both in the plasma and in the cytosol of many tissues, PAF-acetylhydrolases are equally widely distributed in an animal organism. Recent crystallographic studies shed new light on the complex structure-function relationships in PAF-AHs. Received 15 September 1997; received after revision 23 February 1998; accepted 25 February 1998     

The Duhem-Quine problem for equiprobable conjuncts

In this paper, we distinguish Quine’s thesis of holism from the related Duhem-Quine problem. We discuss the construal of holism which claims that the effect of falsification is felt on a conjunction of hypotheses. The Duhem-Quine problem claims that there is no principled way of knowing how falsification affects individual conjuncts. This latter claim relies on holism and an additional commitment to the hypothetico-deductive model of theory confirmation such that it need not arise in non-deductive accounts. While existing personalist Bayesian treatments of the problem make this point by assuming values of priors for the conjuncts, we arrive at the same conclusion without invoking such assumptions. Our discussion focuses on the falsification of equiprobable conjuncts and highlights the role played by their alternatives in ascertaining their relative disconfirmation. The equiprobability of conjuncts is discussed alongside a historical case study     

The utility F-box for protein destruction

A signature feature of all living organisms is their utilization of proteins to construct molecular machineries that undertake the complex network of cellular activities. The abundance of a protein element is temporally and spatially regulated in two opposing aspects: de novo synthesis to manufacture the required amount of the protein, and destruction of the protein when it is in excess or no longer needed. One major route of protein destruction is coordinated by a set of conserved molecules, the F-box proteins, which promote ubiquitination in the ubiquitin-proteasome pathway. Here we discuss the functions of F-box proteins in several cellular scenarios including cell cycle progression, synapse formation, plant hormone responses, and the circadian clock. We particularly emphasize the mechanisms whereby F-box proteins recruit specific substrates and regulate their abundance in the context of SCF E3 ligases. For some exceptions, we also review how F-box proteins function through non-SCF mechanisms.     

The enteric neural receptor for 5-hydroxytryptamine

Summary An enteric neural receptor for serotonin (5-HT) has been characterized. This receptor was assayed, using³H-5-HT as a radiologand, by rapid filtration of isolated enteric membranes and by radioautography. In addition, intracellular recordings were made from ganglion cells of the myenteric plexus. High affinity, saturable, reversible, and specific binding of³H-5-HT was demonstrated both to membranes of the dissected longitudinal muscle with adherent myenteric plexus and the mucosa-submucosa. Radioautographs showed these³H-5-HT binding sites to be in myenteric ganglia and in a broad unresolved band at the mucosal-submucosal interface. Antagonists active at receptors for other neurotransmitters than 5-HT, at either of the two known types of CNS 5-HT receptor, and at 5-HT uptake sites on serotonergic neurons failed to inhibit binding of³H-5-HT. The structural requirements of analogues for binding to the enteric 5-HT receptor matched the known pharmacology of M or neural 5-HT receptors. A novel 5-HT antagonist was found. This compound, N-acetyl-5-hydroxytryptophyl-5-hydroxytryptophan amide (5-HTP-DP), antagonized the action of 5-HT on type II/AH cells of the myenteric plexus but did not affect the release or actions of acetylcholine (nicotinic or muscarinic) or substance P. 5-HTP-DP was also an equally potent displacer of³H-5-HT from its binding sites on enteric membranes. It is concluded that the sites responsible for specific binding of³H-5-HT are enteric M or neural 5-HT receptors. These receptors differ from those now known to be present in the CNS.