检索结果-南通市图书馆

Dielectric confinement on exciton binding energy and nonlinear optical properties in a strained Zn_(1-x_(in))Mg_(x(in))Se/Zn_(1-x(out))Mg_(x(out))Se quantum well

在线全文

学校读者我要写书评

暂无评论

j.urnal of Semiconductors 2012年第9期33卷 1-7页

作者： j.Abraham Hudson Mark A.j.hn peter Department of Physics NPR Arts&Science CollegeNathamDindigul-624401India Department of Physics Government Arts CollegeMelur-625106MaduraiIndia

The band offsets for a Zn1-xin Mgxin Se/Zn1-xout Mgxout Se quantum well heterostructure are determined using the model solid theory. The heavy hole exciton binding energies are investigated with various Mg alloy contents. The effect of mismatch between the dielectric constants between the well and the barrier is taken into account. The dependence of the excitonic transition energies on the geometrical confinement and the Mg alloy is discussed. Non-linear optical properties are determined using the compact density matrix approach. The linear, third order non-linear optical absorption coefficient values and the refractive index changes of the exciton are calculated for different concentrations of magnesium. The results show that the occurred blue shifts of the resonant peak due to the Mg incorporation give the information about the variation of two energy levels in the quantum well width.

关键词： interband emission energy exciton binding energy quantum well

Deletion or underexpression of the Y-chromosome genes CDY2 and HSFY is associated with maturation arrest in American men with nonobstructive azoospermia

在线全文

学校读者我要写书评

暂无评论

Asian j.urnal of Andrology 2012年第5期14卷 676-682页

作者： peter j.Stahl Anna N Mielnik Christopher E Barbieri peter N Schlegel Darius A Paduch Department of Urology Weill Cornell Medical CollegeNew York Presbyterian HospitaI-CornellNew YorkNY 10065USA

Maturation arrest （MA） refers to failure of germ cell development leading to clinical nonobstructive azoospermia. Although the azoospermic factor （AZF） region of the human Y chromosome is clearly implicated in some cases, thus far very little is known about which individual Y-chromosome genes are important for complete male germ cell development. We sought to identify single genes on the Y chromosome that may be implicated in the pathogenesis of nonobstructive azoospermia associated with MA in the American population. Genotype-phenotype analysis of 132 men with Y-chromosome microdeletions was performed. Protein-coding genes associated with MA were identified by visual analysis of a genotype-phenotype map. Genes associated with MA were selected as those genes within a segment of the Y chromosome that, when completely or partially deleted, were always associated with MA and absence of retrievable testicular sperm. Expression of each identified gene transcript was then measured with quantitative RT-PCR in testicular tissue from separate cohorts of patients with idiopathic MA and obstructive azoospermia. Ten candidate genes for association with MA were identified within an 8.4-Mb segment of the Y chromosome overlapping the AZFb region. CDY2and HSFYwere the only identified genes for which differences in expression were observed between the MA and obstructive azoospermia cohorts. Men with obstructive azoospermia had 12-fold higher relative expression of CDY2transcript （1.33__.0.40 vs. 0.11＋_0.04; P=O.O003） and 16-fold higher expression of HSFYtranscript （0.78__.0.32 vs. 0.05_0.02; P=O.O005） compared to men with MA. CDY2 and HSFYwere also underexpressed in patients with Sertoli cell only syndrome. These data indicate that CDY2and HSFYare located within a segment of the Y chromosome that is important for sperm maturation, and are underexpressed in testicular tissue derived from men with MA. These observations suggest that impairments in CDY2 or HSFYexpression could be impli

关键词： CDY1 protein CDY2 protein genetics histology HSFY human make infertility nonobstructive azoospermia spermato-genesis sperm maturation

Distributed Bio-Hydrogen Refueling Stations

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

j.urnal of Earth Science and Engineering 2016年第4期6卷 183-190页

作者： peter j. Schubert Richard G. Lugar Center for Renewable Energy lndiana University-Purdue University Indianapolis Indianapolis 1N 46202 United States

Hydrogen fuel cell cars are now available for lease and for sale. Renewable hydrogen fuel can be produced from water via electrolysis, or from biomass via gasification. Electrolysis is power-hungry with high demand from solar or wind power. Gasification, however, can be energy self-sufficient using a recently-patented thermochemical conversion technology known as I-HPG （indirectly-heated pyrolytic gasification）. I-HPG produces a tar-free syngas from non-food woody biomass. This means the balance of plant can be small, so the overall system is economical at modest sizes. This makes it possible to produce renewable hydrogen from local agricultural residues; sufficient to create distributed refueling stations wherever there is feedstock. This work describes the specifics of a novel bio-hydrogen refueling station whereby the syngas produced has much of the hydrogen extracted with the remainder powering a generator to provide the electric power to the I-HPG system. Thus the system runs continuously. When paired with another new technology, moderate-pressure storage of hydrogen in porous silicon, there is the potential to also power the refueling operation. Such systems can be operated independently. It is even possible to design an energy self-sufficient farm where all electric power, heat, and hydrogen fuel is produced from the non-food residues of agricultural operations. No water is required, and the carbon footprint is negative, or at least neutral.

关键词： Biomass hydrogen distributed generation fuel cell vehicle

Industry Based ＂Hands-On＂ Undergraduate Vibration Course for Engineering and Engineering Technology Students

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

j.urnal of Mechanics Engineering and Automation 2013年第2期3卷 71-77页

作者： Geoffrey j. peter Manufacturing and Mechanical Engineering and Technology Program Oregon Institute of Technology - Wilsonville CampusPortland Oregon 97225 USA

Modem technology and manufacturing methods often require engineers who understand the fundamental principles of vibration theory and who are also skilled in vibration applications. Simply processing, remembering and applying the material learned from lectures and laboratory experiments With artificial criteria are inadequate. Hands-on teaching techniques with real-world problems are needed to complete the engineering students＇ education. This paper demonstrates how hands-on experiments performed in industry support and increase the students＇ understanding of fundamental principles and skill in their applications. Graduates with both knowledge and skill are more competitive in today＇s j.b market. A one-quarter industry-based vibration course was developed and taught with a hands-on segment at the Manufacturing and Mechanical Engineering and Technology （MMET） program at Oregon Institute of Technology （OIT） - Portland Campus. This novel instructional approach provided students with the opportunity to immediately apply material, learned in class and laboratory, in real-world industry situations with real-world problems. This instructional approach is applicable in many engineering fields and the author found the mechanical vibrations class particularly well suited for this instructional design style. The hands-on approach, grounded in the vibration course curriculum, provided a direct link to the fundamentals of vibration in industry. Student comments are included to demonstrate the value perceived by the students. Although this curriculum experiment involved mechanical engineering technology students, it would benefit mechanical engineering students equally well. In addition, the paper provides a brief description of the industries that participated in this proj.ct. Industries were selected because they use vibration based manufacturing, perform extreme testing or design their products to avoid failure due to vibrations.

关键词： Vibrations novel curriculum manufacturing mechanical engineering technology.

RECONSTRUCTING THE ROYAL FAMILY OF RAMESSES Ⅱ AND ITS HIERARCHICAL STRUCTURE

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

j.urnal of Ancient Civilizations 2016年第1期31卷 7-44页

作者： peter j. Brand University of Memphis

Introduction： The Great Family of Ramesses II 2Among his many achievements that have marked Ramesses II as one of Egypt＇s greatest pharaohs, his multiple wives and his stupendous progeny of approximately 100 children stands as one of the most remarkable.3 By comparison with all other pharaohs, he appears unique, from the surviving evidence at least. In fact, we know of more royal sons of Ramesses II than of all the kings of Egypt＇s Eighteenth Dynasty.4 Indeed, the numbers of royal children that appear in the unprecedented monumental processional lists of his sons and daughters on several of his Egyptian and Nubian temples prompted Marj.rie Fisher in her recent study of his sons to suggest that many of these princes may have been his grandchildren instead.5

关键词：层次结构 Fisher 法老王埃及儿子大惯性孩子

The Structure of Low Frequency Phenomena in the Tropics and Its Interaction with the Extratropics

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 1992年第1期9卷 1-16页

作者： peter j.Webster 董敏 Department of Meteorology The Pennsylvania Stale University PA 16802 USA Academy of Meteorological Science State Meteorological Administration Beijing 100081 PRChe structure of planetary scale low freonency phenomena in the tropics is studied and an attempt is made to determine its influence and interactions with phenomena at higher latitudes.In the tropics it is found that the majority of the variance in the zonal wind structure is made up in wave numbers I and 2. During warm events in the Pacific Ocean when the Southern Oscillation Index is negative almost all of the variance resides in the gravest mode which undergoes a 40° eastward phase shift. Meanwhile the second logitudinal mode almost disappears. On the other hand the meridional wind field possesses maximum amplitude at higher wave numbers. However near the equatorthe amplitude is small with extreme values occurring in the subtropics. The difference in scale and the location of cxtrcma of the meridional and zonal wind components indicate that the tropical atmosphere is responding to two different driving mechanisms.Correlation analyses between variations of the zonal wind at reference points along the equator with variations of component elsewhere show that there are strong logitudinal connections. The strongest correlations between the tropics and higher latitudes exist in the region of the equatorial westerlies. In fact stronger correlations occur between variations in U anywhere along the equator and the middle latitudes to the north and south of the equatorial westerlies than to the latitudes immediately to the north and south of the reference points. We interpret this "remote" correlation pattern as indicating a two-stage teleconnection process which emphasizes the importance of the equatorial tropical westerlies of the Pacific Ocean as a "corridor" of communication between the low and high latitudes. The regionality of the correlations confirms to some extent recent theoretical development regarding trapped equatorial modes. Finally

The structure of planetary scale low freonency phenomena in the tropics is studied, and an attempt is made to determine its influence and interactions with phenomena at higher *** the tropics, it is found that the maj.rity of the variance in the zonal wind structure is made up in wave numbers I and 2. During warm events in the Pacific Ocean, when the Southern Oscillation Index is negative, almost all of the variance resides in the gravest mode which undergoes a 40° eastward phase shift. Meanwhile, the second logitudinal mode almost disappears. On the other hand, the meridional wind field possesses maximum amplitude at higher wave numbers. However, near the equator,the amplitude is small with extreme values occurring in the subtropics. The difference in scale and the location of cxtrcma of the meridional and zonal wind components indicate that the tropical atmosphere is responding to two different driving *** analyses between variations of the zonal wind at reference points along the equator with variations of component elsewhere show that there are strong logitudinal connections. The strongest correlations between the tropics and higher latitudes exist in the region of the equatorial westerlies. In fact, stronger correlations occur between variations in U anywhere along the equator and the middle latitudes to the north and south of the equatorial westerlies than to the latitudes immediately to the north and south of the reference points. We interpret this 'remote' correlation pattern as indicating a two-stage teleconnection process which emphasizes the importance of the equatorial tropical westerlies of the Pacific Ocean as a 'corridor' of communication between the low and high latitudes. The regionality of the correlations confirms, to some extent, recent theoretical development regarding trapped equatorial modes. Finally, time lagged correlations from plus and minus six months between variations of U and OLR indicate that the interactio

关键词： In The Structure of Low Frequency Phenomena in the Tropics and Its Interaction with the Extratropics

Claudin-11 and occludin are maj.r contributors to Sertoli cell tight j.nction function, in vitro

在线全文

学校读者我要写书评

暂无评论

Asian j.urnal of Andrology 2016年第4期18卷 620-626页

作者： Mark j.McCabe Caroline FH Foo Marcel E Dinger peter M Smooker peter G Stanton Male Fertility Regulation Laboratory Hudson Institute of Medical Research Monash Medical Centre Clayton Victoria 3168 Australia School of Applied Sciences Royal Melbourne Institute of Technology University Bundoora Victoria 3088 Australia Kinghorn Centre for Clinical Genomics Garvan Institute of Medical Research Darlinghurst New South Wales 2010 Australia St Vincent's Clinical School UNSW Sydney New South Wales 2052 Australia.

The Sertoli cell tight j.nction （T j. is the key component of the blood-testis barrier, where it sequesters developing germ cells undergoing spermatogenesis within the seminiferous tubules. Hormonally regulated claudin-11 is a critical transmembrane protein involved in barrier function and its murine knockout results in infertility. We aimed to assess quantitatively the significance of the contribution of claudin-11 to Tj.function, in vitro, using siRNA-mediated gene silencing. We also conducted an analysis of the contribution of occludin, another intrinsic transmembrane protein of the Tj. Silencing of claudin-11 and/or occludin was conducted using siRNA in an immature rat Sertoli cell culture model. Transepithelial electrical resistance was used to assess quantitatively Tj.function throughout the culture. Two days after siRNA treatment, cells were fixed for immunocytochemical localization of j.nction proteins or lyzed for RT-PCR assessment of mRNA expression. Silencing of claudin-11, occludin, or both resulted in significant decreases in Tj.function of 55% （P 〈 0.01）, 51% （P 〈 0.01）, and 62% （P 〈 0.01）, respectively. Data were concomitant with significant decreases in mRNA expression and marked reductions in the localization of targeted proteins to the Sertoli cell Tj. We provide quantitative evidence that claudin-11 contributes significantly （P 〈 0.01） to Sertoli cell Tj.function in vitro. Interestingly, occludin, which is hormonally regulated but not implicated in infertility until late adulthood, is also a significant （P 〈 0.01） contributor to barrier function. Our data are consistent with in vivo studies that clearly demonstrate a role for these proteins in maintaining normal Tj.barrier structure and function.

关键词： blood-testis barrier claudin-11 occludin Sertoli cell tight j.nction siRNA

Inhibition of kinesin-5 improves regeneration of inj.red axons by a novel microtubule-based mechanism

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2015年第6期10卷 845-849页

作者： peter W.Baas Andrew j.Matamoros Department of Neurobiology and Anatomy Drexel University College of Medicine

Microtubules have been identified as a powerful target for augmenting regeneration of inj.red adult axons in the central nervous system. Drugs that stabilize microtubules have shown some promise, but there are concerns that abnormally stabilizing microtubules may have only limited benefits for regeneration, while at the same time may be detrimental to the normal work that microtubules perform for the axon. Kinesin-5 （also called kifl I or EgS）, a molecular motor protein best known for its crucial role in mitosis, acts as a brake on microtubule movements by other motor proteins in the axon. Drugs that inhibit kinesin-5, originally developed to treat cancer, result in greater mobility of microtubules in the axon and an overall shift in the forces on the microtubule array. As a result, the axon grows faster, retracts less, and more readily enters environments that are inhibitory to axonal regeneration. Thus, drugs that inhibit kinesin-5 offer a novel microtubule-based means to boost axonal regeneration without the concerns that accompany abnormal stabilization of the microtubule array. Even so, inhibiting kinesin-5 is not without its own caveats, such as potential problems with navigation of the regenerating axon to its target, as well as morphological effects on dendrites that could affect learning and memory if the drugs reach the brain.

关键词： microtubule axon kinesin-5 Eg5 regeneration monastrol molecular motor protein

Guest Editorial:Special Section on Active Distribution Networks:Markets,Operations,Planning,and Regulation

在线全文

学校读者我要写书评

暂无评论

j.urnal of Modern Power Systems and Clean Energy 2023年第1期11卷 1-2页

作者： peter Palensky Qixin Chen Marcos j.Rider Delft University of Technology DelftNetherlands Tsinghua University BeijingChina University of Campinas Sao PauloBrazil

THE power system is in change,and the most fundamental changes are happening in the distribution *** passive consumers get active and smart,energy storage and distributed generation appears,and the“grid edge”is upgraded with Intenet of Things(IoT).Gone are the days where distribution infrastructure consisted of passive assets,dimensioned for the worst case of load.

关键词： passive IoT distribution