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MICROSTRUCTURAL EVOLUTION OF AS-CAST ZA27 ALLOY DURING COMPRESSIVE CREEP

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Acta Metallurgica Sinica(English Letters) 2003年第5期16卷 335-341页

作者： X.W.Wei b.L.Shen DepartmentofMaterialsScienceandEngineering SichuanInstituteofTechnologyChengdu610039China DepartmentofMetalScience SichuanUniversityChengdu610065China

Phase transformation and micro structural change of an as-cast ZA27 alloy were investigated during compressive creep by X-ray diffraction technique, SEM and TEM. Compressive creep induced decomposition of α metastable η' phase and a four-phase transformation, α + ε → T' + η and T' → θ, occurred during the compressive creep testing. The occurrence of negative creep in the alloy resulted from the volume expansion caused by the four-phase transformation. A micro structural change was also observed from a lamellar structure into a spheroidized structure in higher creep strain of tested specimens. It provided evidence of compressive creep induced phase transformation which occurred in ageing process.

关键词： microstructure change compressive creep ZA27 alloy

FERONIA Is a key Modulator of brassinosteroid and Ethylene Responsiveness in Arabidopsis Hypocotyls

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Molecular Plant 2010年第3期3卷 626-640页

作者： Stephen D. Deslauriers Paul b. Larsen Department of biochemistry University of California-Riverside Riverside CA 92521 USA

Ethylene signaling is a complex pathway that has been intensively analyzed partly due to its importance to the manifestation of horticultural phenomena, including fruit ripening and tissue senescence. In order to further our un- derstanding of how this pathway is regulated, a screen for Arabidopsis mutants with increased ethylene response was conducted. From this, a mutant was identified as having a dark-grown hypocotyl that is indistinguishable from Col-0 wt in the presence of the ethylene perception inhibitor AgNO3, yet has extreme responsiveness to even low levels of ethylene. Map-based cloning of the mutation revealed a T-DNA insertion in the coding sequence of the receptor-like kinase FERONIA, which is required for normal pollen tube reception and cell elongation in a currently unknown capacity. In contrast to a previous report, analysis of our feronia knockout mutant shows it also has altered responsiveness to brassinosteroids, with etiolated fer-2 seedlings being partially brassinosteroid insensitive with regard to promotion of hypocotyl elonga- tion. Our results indicate that FERONIA-dependent brassinosteroid response serves to antagonize the effect of ethylene on hypocotyl growth of etiolated seedlings, with loss of proper brassinosteroid signaling disrupting this balance and leading to a greater impact of ethylene on hypocotyl shortening.

关键词： FERONIA ethylene brassinosteroid triple response hypocotyl Arabidopsis.

Evolution of aggregate surface texture due to tyre-polishing

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Journal of Central South University 2011年第1期18卷 259-265页

作者：陈先华 b.STEINAUER 王大为 Transportation College Southeast University Institute of Road and Traffic Engineering RWTH-Aachen UniversityD52074Germany

Three kinds of aggregates were polished by genuine pneumatic rubber *** initial states of surface texture and dynamic friction coefficient were measured and their developments in polishing process were *** characterizations of height distribution and power spectral density of aggregate surface texture were *** changes of micro-texture were also investigated based on a fractal filtering method with sound theoretical backgrounds of rubber friction on rough *** height reduction and differential removal of mineral component are observed in polishing *** is concluded that the tyre-polishing action plays the critical roles in the micro-scale texture,and the evolution of friction of aggregate is governed by the micro-texture changes due to the differential removal of mineral component.

关键词： tyre polishing dynamic friction coefficient aggregate surface texture micro-texture

Ab-Initio Study of Cobalt Impurity Effects on Phonon Spectra, Mechanical and Thermal Properties of Single Wall Carbon Nanotube （5,0）

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Chinese Physics Letters 2014年第4期31卷 110-113页

作者： H. Tashakori b. khoshnevisan F. kanjouri Faculty of Physics University of Kashan Kashan Iran Faculty of Physics Kharazmi University Karaj Iran

We use density functional perturbation theory based on the pseudo-potential to calculate the phonon spectrum, phonon density of states, specific heat capacity and mechanical properties of pristine and cobalt doped （5,0） single wall carbon nanotube （CNT）. In the calculations, we consider one Co atom in the center of the unit cell of the tube and it is shown that the pristine （5~0） CNT is nonmagnetic while the Co-doped tube becomes magnetic. Young＇s modulus for both systems is about 1 TPa （＇after Co-doping it goes slightly higher） and the Poisson ratio for the pristine tube becomes quite a bit larger than the doped one. On the other hand, the calculated value of radial breath mode for the pristine CNT is in good agreement with the experimental reports while after Co-doping it is increased. In addition, heat capacity of the doped CNT is reduced, which leads to some important empirical applications.

关键词： Wall Carbon Nanotube Ab-Initio pseudo-potential

黄土高原黄土－古土壤的矿物组成及其环境意义

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地球化学 1994年第C期23卷 113-123页

作者：郑洪汉 b．k．G．Theng J.S.Whitton 中国科学院广州地质新技术研究所，广州510640 DSIRLandResources LowerHuttNewZealand

采自洛川和西峰剖面的３４个黄土－古土壤样品分为砂、粉砂、粘土三个粒级进行了矿物成分分析。结果表明，黄土高原黄土和古土壤的矿物组成基本一致，除了方解石和褐铁矿、磁铁矿因在样品处理时已被剔除未予计算外，其主要矿物是石英、... 详细信息

采自洛川和西峰剖面的３４个黄土－古土壤样品分为砂、粉砂、粘土三个粒级进行了矿物成分分析。结果表明，黄土高原黄土和古土壤的矿物组成基本一致，除了方解石和褐铁矿、磁铁矿因在样品处理时已被剔除未予计算外，其主要矿物是石英、云母、长石和绿泥石。这４种矿物占总量的８８％－９１％，其他矿物有高岭石、蒙脱石、蛭石和少量重矿物。不同地质剖面和不同地层层位的矿物差异主要表现为组成矿物在含量和粒度上的变化。洛川与西峰剖面、古土壤与黄土以及相同古土壤层的上部与下部相比，它们的矿物组成主要表现为前者含有较少长石和较多云母和蛭石，而且颗粒较细，表明在土壤发育过程中使矿物转变的生物化学风化过程和使矿物颗粒由粗变细的物理风化过程并存。这一结果有利于这样一种土壤发育机制解释，即古土壤发育与黄土堆积过程同时进行，只是在古土壤发育时期黄土的堆积过程缓慢，成土作用大于黄土堆积作用而发育土壤。

关键词：黄土高原矿物组成环境意义黄土-古土壤成矿机制矿物变化

美国加利福尼亚州弗朗西斯杂岩和蒙特雷群中燧石的稀土元素、主元素和微量元素:海相细粒沉积物中稀土元素来源的确定

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地质地球化学 1993年第3期21卷 45-56,5页

作者： k.W.Murray R.b.brink 董维全张倩

加利福尼亚州中生代弗朗西斯杂岩和中新世蒙特雷群77个样品的稀土元素(REE)、主元素和微量元素的分析表明,这些样品中Ce异常(Ce/Ce^(++))的程度和总稀土丰度(ΣREE)主要受下述因素控制:1)含金属物质的量;2)陆源物质的直接输入量;3)总埋... 详细信息

加利福尼亚州中生代弗朗西斯杂岩和中新世蒙特雷群77个样品的稀土元素(REE)、主元素和微量元素的分析表明,这些样品中Ce异常(Ce/Ce^(++))的程度和总稀土丰度(ΣREE)主要受下述因素控制:1)含金属物质的量;2)陆源物质的直接输入量;3)总埋藏速率。这些独立过程的相对重要性是以这样的方式变化的,即在大洋盆地横剖面上是以REE相对分馏和ΣREE与大洋盆地沉积环境相对应的方式发生变化的。我们的推断已得到了对已发表的有关REE资料(即河流、滨海、开阔大洋和受洋中脊影响的水体,以及陆源、深海沉积物和含金属沉积物的REE资料)进行的广泛评述的支持。燧石层中记录了扩张洋脊、开放洋盆和大陆边缘环境中的沉积过程。来自含金属物质和陆源物质的影响的相对重要性及海水中清除作用所起的作用,可以根据采样点距扩张洋脊的推测沉积距离(km)以及主元素化学特征和地层关系来估计。Ce/Ce~*值在扩张洋脊的附近很低(～0.29),但随着含金属物质影响的减少和陆源物质影响的增加而趋于逐渐增高(～1)。其它稀土指标(ΣERE,Lu_n/La_n,Eu/Eu~*)也与含金属物质和陆源物质的影响相对应。在扩张洋脊的附近,燧石的ΣREE看来似乎取决于埋藏速率,而页岩的ΣREE则与含金属物质的丰度相对应。在开阔大洋和大陆边缘环境,ΣREE受沉积物暴?

关键词：杂岩燧石稀土族微量元素沉积物

Does white-tailed deer density affect tree stocking in forests of the Eastern United States?

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Ecological Processes 2019年第1期8卷 371-382页

作者： brice b.Hanberry Marc D.Abrams USDA Forest Service Rocky Mountain Research StationRapid CitySD 57702USA Department of Ecosystem Science and Management Pennsylvania State University307 Forest Resources BldgUniversity ParkPA16802USA

background:White-tailed deer(Odocoileus virginianus)have increased during the past century in the *** deer densities may reduce tree regeneration,leading to forests that are understocked,where growing space is not filled completely by *** deer pressure,a major transition in eastern forests has resulted in increased tree ***:To reconcile conflicting trends,we applied generalized linear mixed models to compare deer densities during 1982 and then 1996 to tree stocking after about 30 years and 15 years of potential reductions of small trees by deer,for the entire eastern US and 11 ecological *** also compiled deer browse preferences and compared preferred browse with trends in tree species composition from historical(1620–1900)and current tree ***:The forested area of the eastern US,including a prairie ecological province,was equally well-stocked(52%)and understocked(48%)during 2011–2017 tree *** 1982 deer densities,38%of area had deer densities>5.8 deer/km2 and for 1996,66%of area had deer densities>5.8 deer/*** densities and tree stocking were not related significantly for the entire eastern *** may reduce tree stocking in the Laurentian Mixed Forest;however,this province had both lower deer densities and greater tree stocking than other ***,major tree species trends did not match tree browse ***:Rather than too few trees,too many trees is an ecological problem where historical open oak and pine forests had herbaceous understories,and currently,trees have captured growing *** attribute other drivers than deer to explain this transition.

关键词： Driver Fire Herbivory Open forests Transition Tree density

bioprospection of marine actinomycetes: recent advances,challenges and future perspectives

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Acta Oceanologica Sinica 2019年第6期38卷 1-17页

作者： Swati Sharma Abhay b. Fulke Asha Chaubey CSIR-Indian Institute of Integrative Medicine (CSIR-IIIM) CSIR-Innovation CentreMumbai 400053India Regional Centre CSIR-National Institute of Oceanography (CSIR-NIO)Mumbai 400053India CSIR-Indian Institute of Integrative Medicine Jammu180001India

In exploring new sources for economically important products, marine environment draws particular attention because of its remarkable diversity and extreme conditions;it is known to produce metabolic products of great value. It represents untapped source for the discovery of novel secondary metabolites with varying potential such as antibiotic, anti-tumor, antifouling and cytotoxic properties. Marine actinomycetes distributed throughout the marine environment from shallow to deep sea sediments have proved to be a finest source for this discovery. Secondary metabolites derived from marine actinomycetes have proved their worth in industries based on the research on their properties and wide range applications. Spotlight of the review is range of marine based actinomycetes products and significant research in this field. This shows the capability of marine actinomycetes as bioactive metabolite producers. Additionally, the present review addresses some effective and novel approaches of procuring marine microbial compounds utilizing the latest screening strategies of drug discovery from which traditional resources such as marine actinobacteria has decreased due to declining yields. The aim is in the context of promoting fruitful and profitable results in the near future. The recent surfacing of new technologies for bioprospection of marine actinomycetes are very promising, resulting in high quality value added products, and will be de?ning a new era for bioactive compounds with medical and biotechnological applications.

关键词： marine actinomycetes bioprospection commercial use bioactive compounds genome mining

Stabilization of a high-order harmonic generation seeded extreme ultraviolet free electron laser by time-synchronization control with electro-optic sampling

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High Power Laser Science and Engineering 2015年第2期3卷 1-10页

作者： H.Tomizawa T.Sato k.Ogawa k.Togawa T.Tanaka T.Hara M.Yabashi H.Tanaka T.Ishikawa T.Togashi S.Matsubara Y.Okayasu T.Watanabe E.J.Takahashi k.Midorikawa M.Aoyama k.Yamakawa S.Owada A.Iwasaki k.Yamanouchi RIkEN SPring-8 Center Japan Synchrotron Radiation Research Institute RIkEN Center for Advanced Photonics Japan Atomic Energy Agency The University of Tokyo

A fully coherent free electron laser(FEL) seeded with a higher-order harmonic(HH) pulse from high-order harmonic generation(HHG) is successfully operated for a sufficiently prolonged time in pilot user experiments by using a timing drift feedback. For HHG-seeded FELs, the seeding laser pulses have to be synchronized with electron bunches. Despite seeded FELs being non-chaotic light sources in principle, external laser-seeded FELs are often unstable in practice because of a timing jitter and a drift between the seeding laser pulses and the accelerated electron bunches. Accordingly,we constructed a relative arrival-timing monitor based on non-invasive electro-optic sampling(EOS). The EOS monitor made uninterrupted shot-to-shot monitoring possible even during the seeded FEL operation. The EOS system was then used for arrival-timing feedback with an adjustability of 100 fs for continual operation of the HHG-seeded FEL. Using the EOS-based beam drift controlling system, the HHG-seeded FEL was operated over half a day with an effective hit rate of 20%–30%. The output pulse energy was 20 μJ at the 61.2 nm wavelength. Towards seeded FELs in the water window region, we investigated our upgrade plan to seed high-power FELs with HH photon energy of 30–100 e V and lase at shorter wavelengths of up to 2 nm through high-gain harmonic generation(HGHG) at the energy-upgraded SPring-8Compact SASE Source(SCSS) accelerator. We studied a benefit as well as the feasibility of the next HHG-seeded FEL machine with single-stage HGHG with tunability of a lasing wavelength.

关键词： arrival-timing monitor electro-optic sampling(EOS)