检索结果-南通市图书馆

Microstructures of Ti-48%ni shape memory melt-spun ribbons

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2006年第B1期16卷 92-95页

作者：邢鸿雁 H.Y.KIM s.MIYAZAKI College of Mechanical Engineering Tianjin University of Science and TechnologyTianjin 300222China Institute of Materials science University of TsukubaTsukuba 305-8573Japan

The effect of wheel speed on microstructures of Ti-48%ni (mole fraction) melt-spun ribbons was investigated by X-ray diffractometry, scanning electron microscopy and transmission electron microscopy. When the wheel speed is 26 and 42 m/s, the as-spun ribbons are completely crystallized to the Ti-ni B2 phase. The Ti-rich plate precipitates lying on {100} planes are observed in the as-spun ribbon fabricated with a wheel speed of 26 m/s. The spherical Ti2ni precipitates are observed at grain boundaries in the as-spun ribbons fabricated with a wheel speed of 42 m/s. Amorphous and B2 phases coexist in the as-spun ribbon fabricated with a wheel speed of 52 m/s. The uniformity of grain size in heat treated ribbons decreases with increasing wheel speed.

关键词：形状记忆合金钛-镍薄膜显微结构快淬

Anthropogenic Pseudokarstic Depressions on Mount Bocskor(Bakony region, Hungary)

在线全文

学校读者我要写书评

暂无评论

Journal of Earth science 2023年第1期34卷 214-231页

作者： Márton Veress Zoltán Unger szilárd Vetési-Foith Department of Geography Savaria University centreEötvös Lóránd UniversitySzombathely9700Hungary Institute of Geography University of PécsPécs7600Hungary

surface forms above the mine(ármin mine) of Mount Bocskor(southern Bakony, Hungary) were examined. We made contour maps, plan maps, morphological maps and atectonic grike(cave) maps of some of the forms and their surroundings. We examined the distribution of the depth, length, elongation ratio in case of some depressions, the relation between the depth and the diameter of some depressions, the relationship between depression group directions and mine cut directions, the standard deviation of the direction differences of depression groups and of their depressions. The forms of the mountain related to surface mining can be separated to open and closed. The former are trenches and stairs, the latter are circular, elongated, and complex depressions. The formation of these forms can be related to the balancing movements of the vault over the mountain’s mine. At thin vault, stairs develop by collapses, while at the atectonic fissures of thicker vault, trenches and depressions are formed at the surface. In areas bordered by sinking(subsidence through) and downwardly cohesive faults, depression groups of diverse features are arranged in the marginal bands. Elongated depressions are formed at atectonic blocks bounded by dispersing faults in non-banded distribution. Where there is a superficial deposit, atectonic fissures can also be inherited directly by collapse to the surface and form depressions. They can also form indirectly over atectonic fissures by compaction, subsequent collapse and/or suffosion of the superficial deposit. The results of the study make it possible to analyse the material loss due to mining on the vault if the atectonic structures of the vault are partly or completely covered by superficial deposit.

关键词： mining pseudokarstic depression atectonic fissure atectonic block collapse suffosion

Formation of Co-implanted silicon Ultra-shallow Junctions for Low Thermal Budget Applications

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2013年第1期30卷 127-129页

作者： rehana Mustafa s.Ahmed E.U.Khan Department of Physics International Islamic UniversityIslamabadPakistan Advanced Electronics Laboratory Faculty of Engineering&TechnologyInternational Islamic University IslamabadPakistan Center for Emerging sciences Engineering and TechnologyIslamabadPakistan Department of Physics Gomal UniversityD.I.KhanPakistan

We present a systematic study to create ultra-shallow junctions in n-type silicon substrates and investigate both pre-and post-annealing processes to create a processing strategy for potential applications in *** wafers were co-implanted with indium and C atoms at energies of 70 keV and 10 keV,respectively.A carefully chosen implantation schedule provides an abrupt ultra-shallow junction between 17 and 43 nm with suppressed sheet resistance and appropriate retained sheet carrier concentration at low thermal budget.A defect doping matrix,primarily the behavior and movement of co-implant generated interstitials at different annealing temperatures,may be engineered to form sufficiently activated ultra-shallow devices.

关键词： shallow annealing implantation

Enhancement of second- and Third-Order nonlinear Optical susceptibilities in Magnetized semiconductors

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2008年第9期25卷 3276-3279页

作者： M. singh P. Aghamkar s. Duhan Department of Applied sciences P.D.M. College of Engineering Bahadurgarh-124507 India Department of Applied Physics G.J. University of Science and Technology Hisar-125001 India Department of Physics Chaudhary Devi Lal University Sirsa-125055 India

Using electromagnetic treatment, an expression of effective nonlinear optical susceptibility χe [= χe^（2）＋ χe^（3） E] is obtained for Ⅲ-Ⅴ semiconducting crystals in an applied transverse dc magnetic fieM under off-resonant transition regime. The origin of nonlinear interaction lies in nonlinear polarization arising from the crystal properties such as piezoelectricity and electrostriction. numerical estimates have been made by a representative n-Insb crystal at 77K duly irradiated by a pulsed 10.6-μm CO2 laser under off-resonant transition regime. Efforts are dedicated to optimizing doping level and externally applied dc magnetic field to achieve maximum χe^（2） and χ3^（3）. The results are found to be in good agreement with the available literature. The analysis shows that χe^（2） and χe^（3） can be significantly enhanced in doped Ⅲ-Ⅴ semiconductors by the proper selection of doping concentration and dc magnetic field, which confirms its potential as a candidate material for the fabrication of nonlinear optical devices.

关键词： the power-law exponents precipitation durative abrupt precipitation change

Effects of calcination temperature and time on the Ca3Co4O9 purity when synthesized using starch-assisted sol-gel combustion method

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2020年第2期9卷 162-172页

作者： M.A.MOHAMMED M.B.UDAY s.IZMAn school of Mechanical Engineering Faculty of EngineeringUniversiti Teknologi Malaysia(UTM)UTM Skudai 81310JohorMalaysia Centre for Advanced Composite Materials(CACM) Institute for Vehicle Systems and EngineeringUniversiti Teknologi MalaysiaUTM Skudai 81310JohorMalaysia Department of Materials Engineering College of EngineeringUniversity of BasrahBasrahIraq

Ca3Co4O9 is a p-type semiconducting material that is well-known for its thermoelectric(TE),magnetic,electronic,and electro-optic *** this study,sol–gel autoignition was used to prepare Ca3Co4O9 at different calcination temperatures(773,873,973,and 1073 K)and time(4,6,8,10,12,and 14 h)using starch as a *** phase and microstructure of the prepared Ca3Co4O9 powder were ***–differential thermal analysis(TGA)confirms that the final weight loss occurred at 1073 K to form Ca3Co4O9 stable *** variable-pressure scanning electron microscopy(VP-sEM)images show that the size of powder particles increases from 1.15 to 1.47μm as calcination time increases from 4 to 12 h,and the size remains almost constant thereafter.A similar pattern is also observed on the increment of the crystallite size and percentage of crystallinity with X-ray diffraction(XrD)*** highest crystallinity is found about 92.9%when the powder was calcinated at 1073 K for 12 and 14 h with 458 and 460Åcrystallite size,*** dispersive X-ray spectroscopy(EDs)analysis demonstrates that the calcinated powder has a high intensity of Ca,Co,and O with uniform ***-resolution transmission electron microscopy(HrTEM)images prove that there is no distinct lattice distortion defect on the crystal structure.

关键词： calcium cobalt oxide sol-gel starch combustion method crystallite size crystallinity

Enhancement of a foaming formulation with a zwitterionic surfactant for gas mobility control in harsh reservoir conditions

在线全文

学校读者我要写书评

暂无评论

Petroleum science 2021年第5期18卷 1409-1426页

作者： Miguel Angel roncoroni Pedro romero Jesús Montes Guido Bascialla rosario rodríguez ramón rodríguez Pons-Esparver Luis Felipe Mazadiego María Flor García-Mayoral Universidad Politécnica de Madrid MadridSpain CEPsA research Center MadridSpain CEPsA E&P MadridSpain

This work presents the design of a robust foam formulation that tolerates harsh reservoir conditions(high salinity,high divalent ion concentration,high temperature,light oil,and hydrocarbon injection gas)in a sandstone *** this,we selected anionic Alpha Olefin sulfonate(AOs)surfactants and studied their synergistic effects in mixtures with zwitterionic betaines to enhance foam *** laboratory workflow used to define the best formulation followed a de-risking approach in three consecutive ***,(phase 1)the main surfactant(AOs)was selected among a series of commercial candidates in static ***,(phase 2)the betaine booster to be combined with the previously selected AOs was chosen and their ratio optimized in static ***,(phase 3)the surfactant/booster ratio was optimized under dynamic conditions in a porous medium in the absence and the presence of *** a result of this study,a mixture of an AOs C14-C16 and cocamidopropyl hydroxysultaine(CAPHs)was selected as the one having the best *** designed formulation was proven to be robust in a wide range of *** generated a strong and stable foam at reservoir conditions,overcoming variations in salinity and foam quality,and tolerated the presence of oil.

关键词： Gas mobility control Foam enhanced oil recovery(EOr) Foam stability High temperature high salinity reservoir surfactant formulation

基于XeF(C-A)放大器的混合(固态/气态)超高功率飞秒激光系统(英文)

在线全文

学校读者我要写书评

暂无评论

光学精密工程 2011年第2期19卷 252-259页

作者： LOsEV V aleksEEV s IVAnOV n KOVALCHUK B MIKHEEVL MEsYATs G PAnCHEnKO Yu PUCHIKIn A rATAKHIn n YAsTrEMsKY A Institute of High Current Electronics of siberian Branch of russian Academy of sciences aveAkademichesky 2/3Tomsk 634055Russia Lebedev Physical Institute of russian Academy of sciences Leninsky Prospekt53119991 Russia

提出了基于前端发生器和终端放大器,使用光泵浦XeF（C-A）激活介质的太瓦级混合激光器（THL-100）系统。前端发生器由长532 nm的连续激光泵浦的钛宝石飞秒脉冲振荡器,脉冲展宽机构,532 nm的脉冲激光泵浦的再生多通道放大器,衍射光栅压... 详细信息

提出了基于前端发生器和终端放大器,使用光泵浦XeF（C-A）激活介质的太瓦级混合激光器（THL-100）系统。前端发生器由长532 nm的连续激光泵浦的钛宝石飞秒脉冲振荡器,脉冲展宽机构,532 nm的脉冲激光泵浦的再生多通道放大器,衍射光栅压缩器和二次谐波发生器（KDP）组成。其光束输出参数为：脉冲持续时间50 fs,二次谐波（475 nm）辐射能量5 mJ。前端发生器以10 Hz的单脉冲模式工作。XeF（C-A）放大器由双高压脉冲发生器（线性变压器）,爆炸式阴极发射真空二极管,电子束注入系统,充满Xe的气室转换器和激光单元组成。高压发生器包括12个变压器,每个变压器有8个电容（40 nF）和火花隙,电容可以充电至100 kV。真空二极管中的电子束参数为：总电流300 kA,峰值电压550kV,脉冲持续时间约150 ns。穿透金属箔片到达Xe转换器的6个100 cm×12 cm电子束的总能量为67 kJ。激光系统通过泵浦能量的级联处理导致Xe2＊的快速形成,并在（172±5）nm连续辐射。真空紫外辐射通过CaF2窗口辐射到含有XeF2蒸汽和氮气缓冲气体的激光单元中,使XeF2光解,形成XeF＊准分子。由真空紫外辐射泵浦的放大器激活介质长110 cm,直径为24 cm。文中通过数值模拟给出了输出参数和第一实验结果,根据XeF（C-A）放大器参数模型和增益测量结果,得到的输出能量高达23 J,这意味着50 fs脉冲的峰值功率高达4060 TW。

关键词：混合激光器 XeF(C—A)放大器飞秒脉冲宽度电子束紫外转换器

spatial variability of soil organic carbon stock in an olive orchard at catchment scale in southern spain

在线全文

学校读者我要写书评

暂无评论

International soil and Water Conservation research 2023年第2期11卷 311-326页

作者： Jose A.Gòmez Gema Guzmán Tom Vanwalleghem Karl Vanderlinden Institute for sustainable Agriculture.spanish national research Council(IAs-CsIC) Alameda del Obispo S/N14004CordobaSpain Department of Agronomy University of CordobaCampus de Rabanales14071CordobaSpain Centro IFAPA Alameda del Obispo 14004CordobaSpain

Orchards have a high potential for carbon ***,little research is available on the spatial variability at catchment scale and on the difference between the tree area and the *** analyzed theik spatial variability of soil organic carbon stock,sOCstock at 90 cm depth in an 8-ha catchment in southern spain with olives on a vertic *** showed higher soil organic carbon concentration,sOC,in the tree area as compared to the lane up to 60 cm depth,but its impact on sOCstock was negligible since it was compensated by the higher soil bulk density in the *** at different depths was correlated with that in the top 0-5 *** overall sOCstock of the orchard was 4.14 kg m^(-2),ranging between 1.8 and 6.0 kg m^(-2).This sOCstock is in the mid-lower range of values reported for olive orchards,measured at smaller scale,and similar to those other intensive field crops and agroforestry under comparable rainfall *** spatial variability in sOCstock was correlated to several geomorphological variables:elevation,cumulative upstream area,topographic wetness index,sediment transport index,and tillage *** in sOC and sOCstock are driven by the sediment redis-tribution downslope,mainly by tillage erosion,and higher soil water availability in lower areas allowing higher biomass *** topographic indexes and the correlation between sOC in the topsoil and sOCstock up to 90 cm should be further explored in other typology of olive orchards for facilitating the mapping of sOC_(stock).

关键词： Carbon sequestration Mediterraneancrops Catchment spatial variability Vertic soils

Promise of metformin for preventing age-related cognitive dysfunction

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 2022年第3期17卷 503-507页

作者： Leelavathi n.Madhu Maheedhar Kodali Ashok K.shetty Institute for regenerative Medicine Department of Molecular and Cellular MedicineTexas A&M University College of MedicineCollege StationTXUSA

The expanded lifespan of people,while a positive advance,has also amplified the prevalence of age-related disorders,which include mild cognitive impairment,dementia,and Alzheimer's ***,competent therapies that could improve the healthspan of people have great *** of the dietary and pharmacological approaches that augment the lifespan could also preserve improved cognitive function in old ***,a drug widely used for treating diabetes,is one such candidate that could alleviate age-related cognitive ***,the possible use of metformin to alleviate age-related cognitive dysfunction has met with conflicting results in human and animal *** most clinical studies have suggested the promise of metformin to maintain better cognitive function and reduce the risk for developing dementia and Alzheimer's disease in aged diabetic people,its efficacy in the nondiabetic population is still ***,a previous animal model study implied that metformin could adversely affect cognitive function in the ***,a recent animal study using multiple behavioral tests has reported that metformin treatment in late middle age improved cognitive function in old *** study also revealed that cognitionenhancing effects of metformin in aged animals were associated with the activation of the energy regulator adenosine monophosphate-activated protein kinase,diminished neuroinflammation,inhibition of the mammalian target of rapamycin signaling,and augmented autophagy in the *** proficiency of metformin to facilitate these favorable modifications in the aged hippocampus likely underlies its positive effect on cognitive ***,additional studies probing the outcomes of different doses and durations of metformin treatment at specific windows in the middle and old age across sex in nondiabetic and non-obese prototypes are required to substantiate the promise of metformin to maintain better cognitive fun

关键词： activated microglia aging autophagy cognitive dysfunction memory metformin mTOr signaling neuroinflammation