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181.
The recycling of metals is widely viewed as a fruitful sustainability strategy, but little information is available on the degree to which recycling is actually taking place. This article provides an overview on the current knowledge of recycling rates for 60 metals. We propose various recycling metrics, discuss relevant aspects of recycling processes, and present current estimates on global end‐of‐life recycling rates (EOL‐RR; i.e., the percentage of a metal in discards that is actually recycled), recycled content (RC), and old scrap ratios (OSRs; i.e., the share of old scrap in the total scrap flow). Because of increases in metal use over time and long metal in‐use lifetimes, many RC values are low and will remain so for the foreseeable future. Because of relatively low efficiencies in the collection and processing of most discarded products, inherent limitations in recycling processes, and the fact that primary material is often relatively abundant and low‐cost (which thereby keeps down the price of scrap), many EOL‐RRs are very low: Only for 18 metals (silver, aluminum, gold, cobalt, chromium, copper, iron, manganese, niobium, nickel, lead, palladium, platinum, rhenium, rhodium, tin, titanium, and zinc) is the EOL‐RR above 50% at present. Only for niobium, lead, and ruthenium is the RC above 50%, although 16 metals are in the 25% to 50% range. Thirteen metals have an OSR greater than 50%. These estimates may be used in considerations of whether recycling efficiencies can be improved; which metric could best encourage improved effectiveness in recycling; and an improved understanding of the dependence of recycling on economics, technology, and other factors.  相似文献   
182.
Globozoocephaly was first described in 1971, and 35 years were necessary to identify the first genetic origin (SPATA16 mutation), despite the development of many mice models and the certainty of a genetic origin for this syndrome taking into account observations in many siblings. Despite the recent identification of the new genes PICK1 and DPY19L2, globozoocephaly is still a mystery. This syndrome is probably polymorphic, as suggested by electronic microscopic details, and it is associated with a poor success rate in assisted reproductive tehnology (ART). Further studies are needed to understand the mechanism leading to the globozoocephalia and to define new therapeutic approaches to turn around major spermatic defects associated with this syndrome.  相似文献   
183.
Genetic control of insect pests: growth industry or lead balloon?   总被引:1,自引:0,他引:1  
Genetic control is a form of biological control of pest species which exploits the insect's mate-seeking expertise to introduce genetic abnormalities (typically, but not necessarily, dominant lethal mutations) into the eggs of the wild population. The effectiveness of radiation-sterilized males depends on the mating competitiveness of released males being adequate in relation to the recovery potential of and rate of immigration into the target population. This technique is now being applied on a very large scale against agricultural pests especially in Mexico, Egypt and Japan. Variants on this technique, which may have advantages, include novel means of generating genetic loads in populations of Lepidioptera and sheep blowflies and the introduction into mosquito populations of genes making them unable to transmit malaria.  相似文献   
184.
A polyclonal antibody to ubiquitin has been prepared and shown to react with both ubiquitin and ubiquitinated histone 2A (uH2A). Applying this antibody in Western blotting experiments, we have observed that the salivary glands of Chironomus tentans contain an unusually low amount of uH2A (1% of histone 2A), while the amount of free ubiquitin is as abundant as in other animal cells, e.g. HeLa cells. The same low content of uH2A was also found in diploid epidermal cells of Chironomus origin suggesting that the low amount is not a characteristic of the polytene state of chromatin in salivary gland cells but rather a property of C. tentans as a species. The significance of the low degree of ubiquitination is discussed in relation to the information available on the organization of Chironomus chromatin into unusually large chromomeric entities.  相似文献   
185.
In this paper the recent population changes of the Wild Boar in different European countries is analysed through the study of hunting statistics. A simultaneous increase in numbers is observed throughout the whole area during the period 1965–1975. From 1975 onwards the population stabilizes itself apart from in peripheral areas like Finland. Potentially favourable factors which play a part in this process are discussed and certain reproductive and dispersive characteristics which favour its invasive behaviour are discussed.  相似文献   
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Administration of purified pertussis toxin to rats induced persistent tachycardia, (observed in conscious rats but not after pithing); as little as 0.05 microgram/100 g produced a significant effect. Pertussis toxin-treatment did not affected the pressor response produced in the pithed rats by the alpha 2-adrenergic agonist methoxamine but markedly diminished the pressor effect of the alpha 2-adrenergic agonists clonidine and azepexole. A role of adenylate cyclase inhibition in the action of postsynaptic vascular alpha 2-adrenergic receptors is suggested.  相似文献   
188.
Recombinant human insulin.   总被引:1,自引:0,他引:1  
Insulin is a well-characterized peptide that can be produced by recombinant DNA technology for human therapeutic use. A brief overview of insulin production from both traditional mammalian pancreatic extraction and recombinant bacterial and yeast systems is presented, and detection techniques, including electrophoresis, are reviewed. Analytical systems for insulin separation are principally based on reversed-phase chromatography, which resolves the deamidation product(s) (desamido insulin) of insulin, proinsulin, and insulin. Process-scale separation is a multistep process and includes ion exchange, reversed-phase, and size exclusion chromatography. Advantages and/or disadvantages of various separation approaches, as described by the numerous literature references on insulin purification, are presented.  相似文献   
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