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In producing power, humans move the nutrients nitrogen (N) and phosphorus (P) from their long‐term geological and biological stocks and release or emit them in soil, water, and the atmosphere. In Finland, peat combustion is an important driver of N and P fluxes from the environment to human economy. The flows of N and P in the Finnish energy system were quantified with partial substance flow analysis, and the driving forces of emissions of nitrogen oxides (NOx) were analyzed using the ImPACT model. In the year 2000 in Finland, 140,000 tonnes of nitrogen entered the energy system, mainly in peat and hard coal. Combustion released an estimated 66,000 tonnes of N as nitrogen oxides (NOx) and nitrous oxides (N2O) and another 74,000 tonnes as elemental N2. Most of the emissions were borne in traffic. At the same time, 6,000 tonnes of P was estimated to enter the Finnish energy system, mostly in peat and wood. Ash was mainly used in earth construction and disposed in landfills; thus negligible levels of P were recycled back to nature. During the twentieth century, fuel‐borne input of N increased 20‐fold, and of P 8‐fold. In 1900–1950, the increasing use of hard coal slowly boosted N input, whereas wood fuels were the main carrier of P. Since 1970, the fluxes have been on the rise. NOx emissions leveled off in the 1980s, though, and then declined in conjunction with improvements in combustion technologies such as NOx removal (de‐NOx) technologies in energy production and catalytic converters in cars. 相似文献
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Streptococcus faecium mutants that are temperature sensitive for cell growth and show alterations in penicillin-binding proteins. 总被引:9,自引:2,他引:7 下载免费PDF全文
The penicillin-binding proteins (PBPs) of 209 cell division (or growth) temperature-sensitive mutants of Streptococcus faecium were analyzed in this study. A total of nine strains showed either constitutive or temperature-sensitive conditional damage in the PBPs. Analysis of these nine strains yielded the following results: one carried a PBP 1 constitutively showing a lower molecular weight; one constitutively lacked PBP 2; two lacked PBP 3 at 42 degrees C, but not at 30 degrees C; one was normal at 30 degrees C but at 42 degrees C lacked PBP 3 and overproduced PBP 5; two were normal at 42 degrees C and lacked PBP 5 at 30 degrees C; one constitutively lacked PBP 5; and one carried a PBP 6 constitutively split in two bands. The mutant lacking PBP 3 and overproducing PBP 5 continued to grow at 42 degrees C for 150 min and then lysed. Revertants selected for growth capability at 42 degrees C from the mutants altered in PBPs 5 and 6 maintained the same PBP alterations, while those isolated from the strains with altered PBP 1 or lacking PBP 2 or PBP 3 showed a normal PBP pattern. Penicillin-resistant derivatives were isolated at 30 degrees C from the mutants lacking PBP 2 and from that lacking PBP 3. All these derivatives continued to show the same PBP damage as the parents, but overproduced PBP 5 and grew at 42 degrees C. These findings indicate that high-molecular-weight, but not low-molecular-weight, PBPs are essential for cell growth in S. faecium. This is in complete agreement with previous findings obtained with a different experimental system. On the basis of both previous and present data it is suggested that PBPs 1, 2, and 3 appear necessary for cell growth at optimal temperature (and at maximal rate), but not for cell growth at a submaximal one (or at a reduced rate), and an overproduced PBP 5 is capable of taking over the function of PBPs 1, 2, and 3. 相似文献
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Gianfranco Canti Laura Ricci Ornella Marelli Paola Franco Angelo Nicolin 《Cancer immunology, immunotherapy : CII》1987,24(1):64-67
Summary New antigenic specificities, not detectable on parental cells, have been induced by many investigators in mouse lymphomas by treatment with the antitumor agent 5(3,3-dimethyl-1-triazeno)imidazole-4-carboxamide (DTIC). The antigens are transmissible, after withdrawal of the drug treatment, as an inheritable character. The mechanism of induction, the molecular nature, and the number of the new antigenic specificities have not been completely elucidated. Four clones from murine leukemia L1210 isolated and expanded in vitro were treated in vivo with DTIC and the new sublines were studied in detail. The four drug-treated sublines studied exhibited strong immunogenicity since they were rejected by syngeneic animals. Immunosuppressed animals challenged with 107 A/DTIC or P/DTIC cells were reciprocally protected by the adoptive transfer of spleen cells from donors that had rejected a lethal challenge of A/DTIC or P/DTIC clones. In a similar fashion, the adoptive transfer of spleen cells obtained from animals that had rejected the Q/DTIC or the R/DTIC clones protected immunosuppressed mice challenged with Q/DTIC or R/DTIC cells. No antitumor activity was observed in cross-protective schedules other than those indicated. It was been concluded that (a) the L1210 leukemia line does not have antigenic cells, (b) four DTIC-treated clone sublines were rejected by compatible hosts, and (c) two mutually exclusive sets of antigens were expressed in four antigenic clone sublines.Research supported in part by P.F.O. Contract Grant from C. N. R., Rome, Italy 相似文献
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Purdy LM 《Bioethics》1989,3(1):18-34
The morality of surrogate mothering is analyzed from a "consequentialist" framework which attempts to separate those consequences that invariably accompany a given act from those that accompany it only in particular circumstances. Critics of surrogacy argue that it transfers the burden and risk of pregnancy onto another woman, separates sex and reproduction, and separates reproduction and childrearing; none of these acts is necessarily wrong, either morally or for women's or society's basic interests. While surrogate mothering can be rendered immoral if women are coerced into the practice or become victims of subordinating or penalizing contracts, it has the potential to empower women and increase their status in society by providing a job that is less risky and more enjoyable than other jobs women are forced to take and by achieving greater social recognition for reproductive labor. 相似文献
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Summary The epidermal Merkel cells and their sensory innervation serve tactile sensation in vertebrates. In this study the fluorescent cationic mitochondrial dye, 4-(4-diethylaminostyryl)-N-methylpyridinium iodide (4-Di-2-ASP), which has recently been used as a vital stain for motor and autonomic nerve terminals, was tested for its ability to stain Merkel cells and sensory fibers in the snout of the rat. Brightly-fluorescent structures resembling Merkel cells as well as nerve fibers and their terminations were evident in whole mounts of the vibrissal follicle. Unilateral denervation of the vibrissal follicles soon after birth resulted in a staining pattern remarkably similar to that obtained after labelling of the Merkel cells selectively with the fluorescent marker quinacrine, but all fiber staining was abolished. Likewise, in the separated epidermis of other skin regions, including the hairy and glabrous skin of the nose, the staining pattern revealed by 4-Di-2-ASP was indistinguishable from that obtained by quinacrine fluorescence. These results indicate that certain styryl pyridinium dyes may be used as vital stains for epidermal Merkel cells as well as cutaneous mechanosensory axons. 相似文献