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排序方式: 共有395条查询结果,搜索用时 15 毫秒
1.
Sundaram Vickram Karunakaran Rohini Subramanian Srinivasan David Nancy Veenakumari Kumar Archana Krishnan Anbarasu Palanivelu Jeyanthi Sundaram Thanigaivel Govindarajan Gulothungan Nanmaran Rajendiran Padmalayam Sadanandan Srikumar 《International journal of molecular sciences》2021,22(4)
Zinc (Zn), the second-most necessary trace element, is abundant in the human body. The human body lacks the capacity to store Zn; hence, the dietary intake of Zn is essential for various functions and metabolism. The uptake of Zn during its transport through the body is important for proper development of the three major accessory sex glands: the testis, epididymis, and prostate. It plays key roles in the initial stages of germ cell development and spermatogenesis, sperm cell development and maturation, ejaculation, liquefaction, the binding of spermatozoa and prostasomes, capacitation, and fertilization. The prostate releases more Zn into the seminal plasma during ejaculation, and it plays a significant role in sperm release and motility. During the maternal, labor, perinatal, and neonatal periods, the part of Zn is vital. The average dietary intake of Zn is in the range of 8–12 mg/day in developing countries during the maternal period. Globally, the dietary intake of Zn varies for pregnant and lactating mothers, but the average Zn intake is in the range of 9.6–11.2 mg/day. The absence of Zn and the consequences of this have been discussed using critical evidence. The events and functions of Zn related to successful fertilization have been summarized in detail. Briefly, our current review emphasizes the role of Zn at each stage of human reproduction, from the spermatogenesis process to childbirth. The role of Zn and its supplementation in in vitro fertilization (IVF) opens opportunities for future studies on reproductive biology. 相似文献
2.
Ludmil Drenchev Jerzy Sobczak Rajiv Asthana Savko Malinov 《Journal of Computer-Aided Materials Design》2003,10(1):35-54
Ordered porosity metal materials belong to a relatively new class of porous materials named gasars. This paper presents a mathematical model of the complex physical phenomena in the production of gasars. Analyses for heat transfer, solidification kinetics and gas diffusion were coupled to describe the formation of unique gasar structure. Several criterial functions were introduced to provide significant quantitative information about the relationship between the operating technological parameters and the final structure. The computational outcomes of the numerical simulation were compared with the characteristics of real gasar ingots. The model was applied to determine the boundary conditions that would provide approximately constant physical conditions on the solidification front. The structure sensitiveness of gasars with respect to the different technological parameters is discussed. 相似文献
3.
4.
5.
Jastorff AM Haegler K Maccarrone G Holsboer F Weber F Ziemssen T Turck CW 《Proteomics. Clinical applications》2009,3(11):1273-1287
Multiple sclerosis is characterized by inflammatory demyelination and axonal loss as pathophysiological correlates of relapsing activity and progressive development of clinical disability. The molecular processes involved in this pathogenesis are still unclear as they are quite complex and heterogeneous. In this article we present protein expression analysis of brain and spinal cord tissues from different models of murine experimental autoimmune encephalomyelitis (EAE), the most commonly used animal model for multiple sclerosis. We observed a number of EAE-specific protein expression and PTM differences. Proteome analysis was extended to multiple sclerosis specimens in order to validate the EAE findings. Our findings suggest the regulation of a number of proteins that shed light on the molecular mechanisms of the disease processes taking place in EAE and multiple sclerosis. We found consistent modulation of proteins including serum amyloid P component, sirtuin 2, dihydropyrimidinase-related protein family proteins, stathmin 1, creatine kinase B and chloride intracellular channel protein 1. Functional classification of the proteins by database and the literature mining reveals their association with neuronal development and myelinogenesis, suggesting possible disease processes that mediate neurodegeneration. 相似文献
6.
The purpose of this work was to explore a new feature extraction method for classifying paddy seeds using a feature extraction algorithm to achieve the area ratio, horizontal–slant and front–rear angles and find whether the proposed features have high discriminating power. Another objective was to find the smallest feature set that can ensure highly accurate recognition of seeds. A total of a 100 image features were extracted, and features having significant discriminating power were identified based on the analysis of variance (ANOVA). From the 100 features, 14 features were found to have high discriminating power and from these features, six were selected as the proposed features. Experimental results show that the proposed features and removal of redundant features enhanced the discriminating power of the feature set, and that the proposed features have an excellent discriminating property for seeds. The presented features resulted in the highest classification accuracy (98.8%) when compared to other methods. 相似文献
7.
Novel Ultrahigh-Energy Materials 总被引:3,自引:0,他引:3
M. B. Talawar R. Sivabalan S. N. Asthana H. Singh 《Combustion, Explosion, and Shock Waves》2005,41(3):264-277
This paper reviews the recent work carried out in the field of modern high-energy materials (HEMs) with the emphasis on homoleptic polynitrogen compounds. A large volume of quantum-chemical investigations have predicted the possibility of existence of polynitrogen compounds not only as short-lived transient species but also in the form of isolable discrete molecules. Despite the theoretical speculations, only a few polynitrogen ions are known today in addition to well-entrenched N
1–
3
discovered almost 100 year ago. Extraordinary potential of these green molecules to deliver high amounts of energy in comparison with todays and tomorrows most powerful HEMs, namely, hexanitrohexaazaisowurtzitane (CL-20) and octanitrocubane (ONC), has fuelled the imagination of propellant and explosive engineers and technologists. Research activities are in progress in many quantum-chemical schools to explore the possibility of other promising polynitrogen compounds. After the recent discovery of key synthons/building blocks Mg(N5)2, N
1+
5
SbF
1–
6
, N
1+
5
SbF11, N
1+
5
, N
1+
5
SnF6, and N
1+
5
Sn(CF3)4, the wealth of polynitrogen compounds is just waiting to be harvested by the HEMs community. There are ambitious plans all over the globe to realize N60, which only prove a eco-friendly dense powerhouse of energy.__________Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 3, pp. 29–45, May–June, 2005. 相似文献
8.
As we live in a culture where “everything can be commodified, measured and calculated and can be put in the competitive market for sale, detached from its roots and purpose,” there is need to redefine our humanness in terms of the changing nature of science, technology, and their deeper impact on human life. More than anything else, it is Information Technology that now has tremendous influence on all spheres of our life, and in a sense, IT has become the destiny of our life. And this is where the real trauma lies. On the one hand, our being in the cyberspace opens up new and exciting horizons before us; on the other hand, we ourselves are changed and transformed in the process. The virtual world transforms human users to a problem-solver technocrat. The speed at which Information Technology is changing the way that youth around the world are socializing, playing, and researching, it is the common practice now for a 15-year old to go home and update their MySpace page, followed by playing online games, or looking up the new trendy YouTube video. These forms of technology are often the topic of adolescent conversations as YouTube, blogs, e-magazines, Face book, MySpace, iPhones, and iPods dominate the commercial and social networking market. Some researchers refer to this phenomenon as ubiquitous technology drawing attention to the fact that ubiquitous technology acknowledges the speedy adoption of day-to-day use of technology as a global phenomenon. In this background, this article aims at revisiting the question, “What is to be human in the era of Ubiquitous Technology?” From a feminist perspective, one can still redefine the boundaries between femininity and masculinity in the context of IT and its impact on our lifestyle and thought style. While examining the ways in which our definitions of “woman” and “man” are shifting in this new communication environment, Elizabeth Lane Lawley observes that we cannot fix a single center from which the experiences of women with computer and communication systems can be viewed and that such fixity would only serve to deepen inequities rather than exposing and removing them. She finally submits, “It is possible to use new theoretical perspectives on the shifting boundaries of gender definitions to rethink a previously deterministic view of the effect of new technologies on society, and particularly the effect of those technologies on women. While the gradual absence of the subject from the field of Artificial Intelligence leads to the invisibility of feminine care along with social and relational nature of man, some feminists dismiss the biological sex distinction on such issues and encourage females to ‘imitate man’ and to become more aggressive, assertive and dominating” (Lawley 1993). What are the possible impacts of this new technology on the so-called feminine traits of our human nature? How far our definitions of “woman” and “man” are shifting in this new communication environment? This is what this article seeks to explore. 相似文献
9.
Since the extension of voltage source converter (VSC) based high voltage direct current (HVDC) transmission system to multi-terminal direct current (MTDC) system is easy, the application of MTDC system is more attractive than before. But the VSC based HVDC system is more vulnerable to DC line faults due to the high discharge current from the DC link capacitance. In this aspect, a super conducting fault current limiter (SCFCL) is a better choice to reduce the consequences of DC line faults. The main objective of this paper is to improve the dynamic performance of an offshore wind farm connected multi-terminal VSC-HVDC transmission system by incorporating SCFCL at different locations. Here, the SCFCL integrated MTDC system is modelled in MATLAB/Simulink and the results are presented for various AC/DC fault conditions. 相似文献
10.
Nirupama Mallick Shovon Mandal Amit Kumar Singh Moumita Bishai Archana Dash 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(1):137-145
BACKGROUND: A major bottleneck in microalgal biodiesel production is lipid content, which is often low in microalgal species. The present study examines Chlorella vulgaris as a potential feedstock for biodiesel by identifying and evaluating the relationships between the critical variables that enhance the lipid yield, and characterizes the biodiesel produced for various properties. RESULTS: Factors affecting lipid accumulation in a green microalga, Chlorella vulgaris were examined. Multifactor optimization raised the lipid pool to 55% dry cell weight against 9% control. When C. vulgaris cells pre‐grown in glucose (0.7%)‐supplemented medium were transferred to the optimized condition at the second stage, the lipid yield was boosted to 1974 mg L?1, a value almost 20‐fold higher than for the control. The transesterified C. vulgaris oil showed the presence of ~82% saturated fatty acids, with palmitate and stearate as major components, thus highlighting the oxidative stability of C. vulgaris biodiesel. The fuel properties (density, viscosity, acid value, iodine value, calorific value, cetane index, ash and water contents) are comparable with the international (ASTM and EN) and Indian (IS) biodiesel standards. CONCLUSION: C. vulgaris biomass with 55% lipid content and adequate fuel properties is potentially a renewable feedstock for biodiesel. Copyright © 2011 Society of Chemical Industry 相似文献