傅立叶变换红外光谱法快速鉴别非金属矿物中重烧镁

重烧镁外观与高岭土、白云石及硅灰石等矿物的外观极为相似,常被混入这些矿石中向境外走私。为了快速鉴别这些矿物中的重烧镁,实验采用傅里叶变换红外光谱技术分别研究了具有不同重烧镁含量的三种矿物其光谱特征,并与重烧镁及不含重烧镁的矿物谱图进行比对。结果表明,当这些矿物中混入一定量的重烧镁时,重烧镁的红外特征吸收峰依然明显存在。当只含有10%的重烧镁,根据谱图的特征变化,依然能够鉴别出这些矿物中混入的重烧镁,即鉴定这些矿物中重烧镁的检出限为10%。方法对实际样品进行了分析,分析结果与化学法相符。     

Resistance of eels (Gymnothorax) to the venom of sea kraits (Laticauda colubrina): a test of coevolution

This study calculated yearly estimated national hospital discharge (1985 to 1994) and age-adjusted death rates (1980 to 1992) due to bacterial, viral, protozoal, and ill-defined enteric pathogens. Infant and young child hospitalization (but not death) rates in each category increased more than 50% during 1990 to 1994. Age-adjusted death and hospitalization rates due to enteric bacterial infections and hospitalizations due to enteric viral infections have increased since 1988. The increases in hospitalization and death rates from enteric bacterial infections were due to a more than eightfold increase in rates for specified enteric bacterial infections that were uncoded during this period (ICD9 00849). To identify bacterial agents responsible for most of these infections, hospital discharges and outpatient claims (coded with more detail after 1992) were examined for New Mexico's Lovelace Health Systems for 1993 to 1996. Of diseases due to uncoded enteric pathogens, 73% were due to Clostridium difficile infection. Also, 88% of Washington State death certificates (1985 to 1996) coded to unspecified enteric pathogen infections (ICD0084) listed C. difficile infection.     

Myocardial involvement in diphtheria patients (a review)

The authors analyze emotional features in workers with occupational exposure to hydrazines, hydrocarbons and nitroglycols. Chronic occupational poisoning with those chemicals induce numerous emotional symptoms that are specific and varying in severity. The materials presented by authors could be interesting for occupational therapist, internist and psychiatrist for early diagnosis of chronic occupational intoxications, treatment of emotional disorders in workers and better occupational safety.     

Composites for contacts and electrodes (a review)

The research done on composites of the type of W(Mo)- and Ag(Cu)-based pseudoalloys for electric switchgear contacts (make and break contacts) is reviewed. The ideas of I. N. Frantsevich on composites for electrical uses are shown to have had a great influence on the development of this field in materials sciences and on the work of his pupils and followers. The distinctive features of composites and parts made to satisfy specific requirements for increased adhesiveness and service life and lower consumption of expensive materials are described.Institute of Materials Science, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 7/8(380), pp. 32–53, July–August, 1995.     

Cloning and sequencing of a full-length sea bream (Sparus aurata) beta-actin cDNA

The pathogenesis of human African trypanosomiasis (HAT) has been the object of considerable research interest but has remained incompletely understood. The importance of cytokines in the pathophysiology of this protozoan infection is now widely recognized, but the full spectrum of cytokines involved has yet to be determined. In the present investigation we compared the plasma concentrations of TNF-alpha and IL-10 in normal African controls and patients suffering from advanced meningocephalic (late-stage) Trypanosomiasis brucei (T.b.) gambiense infections, before and after treatment with the arsenical trypanocide melarsoprol. We found that patients with late-stage T. b. gambiense exhibit chronically elevated circulating levels of both of these cytokines, and that these levels quickly decline following melarsoprol treatment. These findings confirm that TNF-alpha is involved in the immunopathogenesis of late-stage African trypanosomiasis and suggest that IL-10 may also play an important regulatory role in this disease.     

The origin and evolution of viruses (a review)

Viroids and prions might have existed early at the border of inanimate and living worlds. Most extant viruses can be characterized as derivatives of ancestors originating from episomal elements of prokaryotes (DNA phages) and later from eukaryotes. Retroviruses very likely originated from cellular retrotransposons. Retrograde evolution of some large viruses from obligatory intracellular bacteria is possible but the ontogenesis of extant bacteria does not include a viral form of existence (the filterable L forms are not viruses) and well-defined viruses do not regenerate back into vegetative bacterial forms. Biologists experimenting with the evolution of prokaryotic and eukaryotic ancient cells cannot ignore the earliest appearance of viruses within or outside the living matter. Viruses participated in and gave direction to the evolution and natural selection by coexisting with uni- and multicellular organisms for billions of years. The coevolution of viruses and their host cells is characterized by incessant attacks and counterattacks through gene rearrangements and mutations (induced in the virus by an immunological counterattack of the host or by transgression of species barriers by the virus) and recombinations. Recombinations occurred between viral and viral or viral and host genes. Acts of "molecular piracy" as practiced by ancient viruses endowed the virus with the expression of several host genes for the advantage of the virus in its replicative cycle and host-to-host spread. Probably the first immortalized and malignantly transformed cells were induced by viruses as viruses evolved anti-apoptotic measures. While infected cells resort to apoptotic death before the assembly of a new viral progeny, prominent are the anti-apoptotic measures viruses evolved in order to assure the completion of their full replicative cycle. Further, viruses may escape neutralization by host antibodies and may survive a counterattack by the host's T cells directed at virally infected cells of its own. Viruses may induce a form of tolerance and coexist with their host without inducing disease. Persistent and apparently or deceivingly apathogenic or even attenuated viral "quasi-species" populations may contain individual particles that regain virulence due to recombinations and/or gene rearrangements, especially when transgressing species barriers. Xenotropic viruses of animals may replicate in human cells and vice versa confounding experiments with xenotransplants or with use of veterinary viral vaccines for the treatment of human diseases.     

Fractographic features of the fractures of W-Ni-Fe alloy (90:7:3) (a review)

Conclusions The fractographic features of the fractures of W-Ni-Fe (9073) powder composite material depend upon the character of fracture of the basic structural constituents.The refractory constituent may fracture in the grain boundaries (W-Ni, W-W) and transgranularly with the formation of a fan-shaped, river, or herringbone pattern. Fracture of the -solid solution may also be inter- and transgranular by brittle rupture without traces of plastic deformation (in the boundaries of the grain colonies and the basic structural constituents), by the formation and merging of voids, and by shear leading to pulling out "at the tooth" and failure of the cross-links (in the volume of the grain and in the boundary zones).The change in the forms of fracture, including at the boundaries of the basic structural constituents, in accordance with the conditions of the metallurgical process reflects the concurrent influence of segregation phenomena on the boundaries and of the processes of decomposition of the -solid solution on the geometry, degree of deformation, ratio of the properties, and mechanisms of fracture of the body of the grain and the boundary volumes in these constituents.The combination of different forms of fracture of the structural constituents in relation to the production prehistory influences the position of the ductile-to-brittle transition temperature range and, consequently, the properties of the alloy at a specified temperature. The alloy with increased strength and plasticity characteristics at room temperature is characterized by primarily transgranular fracture of the grains of the refractory constituent and of the -solid solution in which these grains are dispersed.Further investigations of the alloy must be directed to studying by transmission electron microscopy the fine crystalline structure of the basic constituents (nickel-base aging solid solutions and tungsten) and revealing the conditions of formation of the optimum structure of these constituents and the adhesion-strong boundaries providing occurrence of the effect of composition hardening.Obtaining the required level and stability of the properties of W-Ni-Fe alloy is related to establishment of the allowable interstitial element impurity content, revealing of the "dangerous" substitutional impurities, and optimization of the conditions of heating, cooling, and heat treatment providing a reduction in the influence of segregation phenomena in the boundary volumes on the geometry of deformation and on fracture.Translated from Poroshkovaya Metallurgiya, No. 2(266), pp. 81–92, February, 1985.     

Reagents types in flotation of iron oxide minerals: A review

Recently, beneficiation of iron from low-grade ores with high impurities has been a matter of discussion. Flotation is one of the most effective technologies for the upgrading of low-grade, finely grained iron ores. This method can also be applied to reduce the impurities content in magnetite concentrates obtained using wet low- and high-intensity magnetic separations. In this paper, several studies describing the processing of iron ores via direct and reverse cationic and anionic flotation are reviewed. The objective of this review was to present and identify the effects of different flotation conditions on removal of specific impurities in iron ore such as quartz, alumina, phosphorous, and sulfur. Novel and common used collectors, depressants, auxiliary reagents, and their mixtures in the flotation are tabulated. This paper attempts to provide an explanation for the current state and use of iron ore flotation methods, as well as to present some ideas on future initiatives and potential developments within the area.