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Effects of leukemia inhibitory factor and basic fibroblast growth factor on free radicals and endogenous stem cell proliferation in a mouse model of cerebral infarction 被引量:2
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作者 Weihui Huang Yadan Li +2 位作者 Yufeng Lin Xue Ye Dawei Zang 《Neural Regeneration Research》 SCIE CAS CSCD 2012年第19期1469-1474,共6页
The present study established a mouse model of cerebral infarction by middle cerebral artery occlusion, and monitored the effect of 25 tJg/kg leukemia inhibitory factor and (or) basic fibroblast growth factor admini... The present study established a mouse model of cerebral infarction by middle cerebral artery occlusion, and monitored the effect of 25 tJg/kg leukemia inhibitory factor and (or) basic fibroblast growth factor administration 2 hours after model establishment. Results showed that following administration, the number of endogenous neural stem cells in the infarct area significantly increased, malondialdehyde content in brain tissue homogenates significantly decreased, nitric oxide content, glutathione peroxidase and superoxide dismutase activity significantly elevated, and mouse motor function significantly improved as confirmed by the rotarod and bar grab tests. In particular, the effect of leukemia inhibitory factor in combination with basic fibroblast growth factor was the most significant. Results indicate that leukemia inhibitory factor and basic fibroblast growth factor can improve the microenvironment after cerebral infarction by altering free radical levels, improving the quantity of endogenous neural stem cells, and promoting neurological function of mice with cerebral infarction. 展开更多
关键词 leukemia inhibitory factor basic fibroblast growth factor endogenous neural stem cells free radical MALONDIALDEHYDE nitric oxide glutathione peroxidase superoxide dismutase NEUROPROTECTION
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Direct Growth of Graphene on Silicon by Metal-Free Chemical Vapor Deposition 被引量:5
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作者 Lixuan Tai Daming Zhu +7 位作者 Xing Liu Tieying Yang Lei Wang Rui Wang Sheng Jiang Zhenhua Chen Zhongmin Xu Xiaolong Li 《Nano-Micro Letters》 SCIE EI CAS 2018年第2期12-20,共9页
The metal-free synthesis of graphene on singlecrystal silicon substrates, the most common commercial semiconductor, is of paramount significance for many technological applications. In this work, we report the growth ... The metal-free synthesis of graphene on singlecrystal silicon substrates, the most common commercial semiconductor, is of paramount significance for many technological applications. In this work, we report the growth of graphene directly on an upside-down placed,single-crystal silicon substrate using metal-free, ambientpressure chemical vapor deposition. By controlling the growth temperature, in-plane propagation, edge-propagation, and core-propagation, the process of graphene growth on silicon can be identified. This process produces atomically flat monolayer or bilayer graphene domains, concave bilayer graphene domains, and bulging few-layer graphene domains. This work would be a significant step toward the synthesis of large-area and layer-controlled, high-quality graphene on single-crystal silicon substrates. 展开更多
关键词 GRAPHENE SILICON Metal-free CVD Domain growth
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Physical Properties and Regulating Mechanism of Fluoride-Free and Harmless B_2O_3-Containing Mould Flux 被引量:9
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作者 LI Gui-rong WANG Hong-ming DAI Qi-xun ZHAO Yu-tao LI Jing-sheng 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2007年第1期25-28,共4页
The flux agents in common mould fluxes were fluoride and sodium oxide, which would do great harm to environments. B2O3 was selected as flux. The physical properties of B2O3-containing mould fluxes were studied. The co... The flux agents in common mould fluxes were fluoride and sodium oxide, which would do great harm to environments. B2O3 was selected as flux. The physical properties of B2O3-containing mould fluxes were studied. The corresponding physical properties of 37. 91% CAO-43.09% SiO2-5% Al2O3-5% MgO-2% Li20-7% B2O3 mould fluxes were as follows: the melting point was 909℃, the flowing temperature was 1 160℃, the viscosity and surface tension at 1300 ℃ were 0. 4 Pa · s and 0.32 N/m respectively, which could meet the demands for certain kinds of steels for mould fluxes in continuous casting. 展开更多
关键词 B2O3 -containing mould flux fluoride-free flux harmless flux physical property
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Physical modeling of behaviors of cast-in-place concrete piled raft compared to free-standing pile group in sand 被引量:1
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作者 Mehdi Sharafkhah Issa Shooshpasha 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2018年第4期703-716,共14页
Similar to free-standing pile groups, piled raft foundations are conventionally designed in which the piles carry the total load of structure and the raft bearing capacity is not taken into account. Numerous studies i... Similar to free-standing pile groups, piled raft foundations are conventionally designed in which the piles carry the total load of structure and the raft bearing capacity is not taken into account. Numerous studies indicated that this method is too conservative. Only when the pile cap is elevated from the ground level,the raft bearing contribution can be neglected. In a piled raft foundation, pileesoileraft interaction is complicated. Although several numerical studies have been carried out to analyze the behaviors of piled raft foundations, very few experimental studies are reported in the literature. The available laboratory studies mainly focused on steel piles. The present study aims to compare the behaviors of piled raft foundations with free-standing pile groups in sand, using laboratory physical models. Cast-in-place concrete piles and concrete raft are used for the tests. The tests are conducted on single pile, single pile in pile group, unpiled raft, free-standing pile group and piled raft foundation. We examine the effects of the number of piles, the pile installation method and the interaction between different components of foundation. The results indicate that the ultimate bearing capacity of the piled raft foundation is considerably higher than that of the free-standing pile group with the same number of piles. With installation of the single pile in the group, the pile bearing capacity and stiffness increase. Installation of the piles beneath the raft decreases the bearing capacity of the raft. When the raft bearing capacity is not included in the design process, the allowable bearing capacity of the piled raft is underestimated by more than 200%. This deviation intensifies with increasing spacing of the piles. 展开更多
关键词 free-standing pile group Piled raft Pileesoileraft interaction physical modeling Cast-in-place concrete piles
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Free-Energy and Emittance Growth Caused by Bunched Beam with Nonuniform Distributions in Both Longitudinal and Transverse Directions in Linac
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作者 Huang, Zhibin Chen, Yinbao Fu, Shinian 《Chinese journal of nuclear physics》 EI 1995年第4期345-352,共8页
The nonlinear space charge effect of bunched beam in linac is one of theimportant factors that induces the emittance growth due to the conversion of thefield energy to kinetic energy. Using a cylinder model of space c... The nonlinear space charge effect of bunched beam in linac is one of theimportant factors that induces the emittance growth due to the conversion of thefield energy to kinetic energy. Using a cylinder model of space charge in a linac,we derive the internal energy for a bunched beam with some nonuniform spacecharge distributions, such as Gaussian, waterbag and parabolic distributions inboth the longitudinal and transverse directions. And the emittance growth causedby these nonuniformities is worked out. 展开更多
关键词 free energy EMITTANCE growth Longitudinal NONUNIFORM DISTRIBUTION Transverse NONUNIFORM DISTRIBUTION
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Reliability of Passive Physical Activity Assessment for Inpatients Using Marker⁃Free Motion Tracking System
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作者 Biao Yang Kewei Duan Wanxia Yao 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2021年第2期21-27,共7页
Evidence⁃based practices of public health will benefit from quantification of passive physical activity assessment.This study aims to investigate the reliability of marker⁃free system(MFS)such as Microsoft Kinect in m... Evidence⁃based practices of public health will benefit from quantification of passive physical activity assessment.This study aims to investigate the reliability of marker⁃free system(MFS)such as Microsoft Kinect in measuring upper extremity motion from different angles.Ten healthy participants performed elbow and shoulder extension/flexion along frontal and median anatomical planes for ten pace⁃controlled repetitions,during which the spatiotemporal positions of upper extremity joints were concurrently recorded by two sensors from 0°and 45°viewing angles.Reliability between the two sensors were evaluated using Pearson correlation coefficient,intra⁃class correlation coefficients,and 95%limits of agreement and coefficient of variation.Worse reliability was observed when possibility of occlusion was higher.However,better reliability was found when longer observation interval(10 s)was used as elementary measuring unit than shorter observation interval(2 s).The overall angular reliability of activity as displacement or changes in angle was not satisfactory.The results are expected to inform the industry for the extension of MFS to clinic applications. 展开更多
关键词 physical activity passive assessment marker⁃free motion tracking system intra⁃class correlation coefficients limits of agreement
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A Physical Insight into the Origin of the Corrections to the Magnetic Moment of Free and Bound Electron
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作者 Nicolae Bogdan Mandache 《Journal of Modern Physics》 2020年第9期1301-1311,共11页
The main goal of the present work is a unitary approach of the physical origin of the corrections to the magnetic moment of free and bound electron. Based on this approach, estimations of lowest order corrections were... The main goal of the present work is a unitary approach of the physical origin of the corrections to the magnetic moment of free and bound electron. Based on this approach, estimations of lowest order corrections were easily obtained. In the non-relativistic limit, the Dirac electron appears as a distribution of charge and current extended over a region of linear dimension of the order of Compton wavelength, which generates its magnetic moment. The e.m. mass (self-energy) of electron outside this region does not participate to this internal dynamics, and consequently does not contribute to the mass term in the formula of the magnetic moment. This is the physical origin of the small increase of the magnetic moment of free electron compared to the value given by Dirac equation. We give arguments that this physical interpretation is self-consistent with the QED approach. The bound electron being localized, it has kinetic energy which means a mass increase from a relativistic point of view, which determines a magnetic moment decrease (relativistic Breit correction). On the other hand, the e.m. mass of electron decreases at the formation of the bound state due to coulomb interaction with the nucleus. We estimated this e.m. mass decrease of bound electron only in its internal dynamics region, and from it the corresponding increase of the magnetic moment (QED correction). The corrections to the mass value are at the origin of the lowest order corrections to the magnetic moment of free and bound electron. 展开更多
关键词 Magnetic Moment of Dirac Electron Electromagnetic Self-Energy physical Origin of the Corrections to the Magnetic Moment of free and Bound Electron
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Dispersion relation and growth rate for a corrugated channel free-electron laser with a helical wiggler pump
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作者 A.Hasanbeigi H. Mehdian 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第7期364-368,共5页
The effects of corrugated ion channels on electron trajectories and spatial growth rate for a free-electron laser with a one-dimensional helical wiggler have been investigated. Analysis of the steady-state electron tr... The effects of corrugated ion channels on electron trajectories and spatial growth rate for a free-electron laser with a one-dimensional helical wiggler have been investigated. Analysis of the steady-state electron trajectories is performed by solving the equations of motion. Our results show that the presence of a corrugated channel shifts the resonance frequency to smaller values of ion channel frequency. The sixth-order dispersion equation describing the coupling between the electrostatic beam mode and the electromagnetic mode has also been derived. The dispersion relation characteristic is analyzed in detail by numerical solution. Results show that the growth rate of instability in the presence of corrugated ion channels can be greatly enhanced relative to the case of an uniform ion channel. 展开更多
关键词 corrugated ion-channel free-electron laser growth rate helical wiggler
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C_4作物FACE(free-air CO_2 enrichment)研究进展 被引量:17
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作者 王云霞 杨连新 +1 位作者 Remy Manderscheid 王余龙 《生态学报》 CAS CSCD 北大核心 2011年第5期1450-1459,共10页
持续迅速上升的大气二氧化碳浓度([CO2])是全球变暖最大的驱动因子,但其作为光合作用底物直接增加了作物的生产力。相比C3作物,人们对未来高浓度CO2情形下C4作物的响应规律认识较少。与封闭或半封闭气室研究相比,FACE(free-airCO2 enric... 持续迅速上升的大气二氧化碳浓度([CO2])是全球变暖最大的驱动因子,但其作为光合作用底物直接增加了作物的生产力。相比C3作物,人们对未来高浓度CO2情形下C4作物的响应规律认识较少。与封闭或半封闭气室研究相比,FACE(free-airCO2 enrichment)试验在空气自由流动的大田条件下对作物表现进行研究,它提供了对未来作物生长环境的真实模拟,因此提供了评估CO2肥料效应以及揭示植物响应机制的最好机会。作为人类重要的粮食和饲料来源,高粱和玉米是最重要的C4作物。在简介美国玉米和高粱FACE系统的基础上,综述了FACE情形下高浓度CO2(模拟本世纪中叶大气CO2浓度,即550μmol/mol)对两大作物生理、生长和产量以及土壤特性等方面的影响,同时比较了与气室研究结果的异同点。(1)FACE使干旱条件下两作物光合作用显著增强,但湿润条件下没有影响;FACE条件下高粱出现光合适应现象,而玉米没有;(2)FACE使两作物气孔导度大幅下降,导致叶温升高、蒸腾速率下降、蒸发蒸腾总量减少或没有变化、叶片总水势和水分利用效率增加或没有变化;(3)FACE对两作物物候期和化学组分影响很少;(4)FACE使干旱条件下两作物生长和产量略有增加,但湿润条件下没有影响;(5)FACE使高粱田土壤丛枝状菌根真菌的长度和易提取胶状物质浓度显著增加,导致水稳性土壤团聚体增加;FACE对高粱田N2O或含氮气体(N2O+N2)的排放没有影响;(6)高浓度CO2对两作物气孔导度的影响FACE试验明显大于气室试验,而对生长和产量的影响呈相反趋势。阐明CO2与基因型、土壤湿度和大气温度间的互作效应及其机制是下一轮C4作物FACE研究优先考虑的方向,技术的不断进步已为利用大型FACE系统来研究这些互作效应提供了可能。 展开更多
关键词 FACE(freeair CO2 enrichment) 二氧化碳 高粱 玉米 生理 生长 土壤
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Evaluation of the Characteristics of Virus-free Sweetpotato and Its Use in Hybridization 被引量:5
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作者 MA Dai-fu, LI Xiu-ying, LI Hong-min, XIE Yi-ping WANG Yi, ZHANG Li-ming, LIU Zhang-xiong and LI Qiang(Xuzhou Sweetpotato Research Center, Jiangsu 221121 CIP-Beijing Liaison Office, Beijing 100081 Shandong Academy ofAgricultural Sciences, Jinan 250100) 《Agricultural Sciences in China》 CAS CSCD 2002年第3期251-255,共5页
Application of virus-free sweetpotato is a breakthrough of sweetpotato production. Several popular varieties were adopted to study their yield increase potential and their use in breeding in this research. The results... Application of virus-free sweetpotato is a breakthrough of sweetpotato production. Several popular varieties were adopted to study their yield increase potential and their use in breeding in this research. The results showed that after virus-elimination, all varieties had a yield increase ranging from 14.95% - 91. 61% and marketable quality improvement, despite the changes in location and season. The changes of dry matter content and disease resistance were not significant. Virus-free sweetpotato performed vigorous vine growth and strong dry matter assimilation ability. Virus-free parents had a slightly high seed setting percentage, but its flowering ability and performance of off-springs were similar to that of its check plants. 展开更多
关键词 SWEETPOTATO VIRUS-free growth habit Dry matter content Disease resistance
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From free chromatin analysis to high resolution fiberFISH
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作者 HENGHENRYHQ XIAOMEISHI 《Cell Research》 SCIE CAS CSCD 1997年第1期119-124,共6页
关键词 free chromatin fiber-FISH physical mapping chromosome and genome
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Mobile user forecast and power-law acceleration invariance of scale-free networks 被引量:1
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作者 郭进利 郭曌华 刘雪娇 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第11期548-555,共8页
This paper studies and predicts the number growth of China's mobile users by using the power-law regression. We find that the number growth of the mobile users follows a power law. Motivated by the data on the evolut... This paper studies and predicts the number growth of China's mobile users by using the power-law regression. We find that the number growth of the mobile users follows a power law. Motivated by the data on the evolution of the mobile users, we consider scenarios of self-organization of accelerating growth networks into scale-free structures and propose a directed network model, in which the nodes grow following a power-law acceleration. The expressions for the transient and the stationary average degree distributions are obtained by using the Poisson process. This result shows that the model generates appropriate power-law connectivity distributions. Therefore, we find a power-law acceleration invariance of the scale-free networks. The numerical simulations of the models agree with the analytical results well. 展开更多
关键词 mobile user forecast power-law accelerating growth complex networks scale-free net-works
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Model Free Adaptive Predictive Control of Desulfurization Slurry pH Based on CPS Framework
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作者 Jian Liu Xiaoli Li +2 位作者 Kang Wang Fuqiang Wang Guimei Cui 《Journal of Beijing Institute of Technology》 EI CAS 2020年第4期544-555,共12页
In order to improve the slurry pH control accuracy of the absorption tower in the wet flue gas desulfurization process,a model free adaptive predictive control algorithm for the desulfurization slurry pH which is base... In order to improve the slurry pH control accuracy of the absorption tower in the wet flue gas desulfurization process,a model free adaptive predictive control algorithm for the desulfurization slurry pH which is based on a cyber physical systems framework is proposed.First,aiming to address system characteristics of non-linearity and pure hysteresis in slurry pH change process,a model free adaptive predictive control algorithm based on compact form dynamic linearization is proposed by combining model free adaptive control algorithm with model predictive control algorithm.Then,by integrating information resources with the physical resources in the absorption tower slurry pH control process,an absorption tower slurry pH optimization control system based on cyber physical systems is constructed.It is turned out that the model free adaptive predictive control algorithm under the framework of the cyber physical systems can effectively realize the high-precision tracking control of the slurry pH of the absorption tower,and it has strong robustness. 展开更多
关键词 wet flue gas desulfurization slurry pH cyber physical systems model free adaptive predictive control tracking control
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Dispersion and Polar Component of Specific Surface Free Energy of NaCl(100), KCl(100), and KBr(100) Single Crystal Surfaces
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作者 Takaomi Suzuk Yuya Yamada 《Journal of Crystallization Process and Technology》 2015年第3期43-47,共5页
Contact angle of ethylene glycol and formamide on (100) faces of NaCl, KCl, and KBr single crystal was measured, and the specific surface free energy (SSFE) was calculated. Dispersion component of the SSFE was 90.57, ... Contact angle of ethylene glycol and formamide on (100) faces of NaCl, KCl, and KBr single crystal was measured, and the specific surface free energy (SSFE) was calculated. Dispersion component of the SSFE was 90.57, 93.78, and 99.52 mN&#183m-1 for NaCl, KCl, and KBr, respectively. Polar component of the SSFE was 1.05, 0.65, and 0.45 mN&#183m-1 for NaCl, KCl, and KBr. Such a large ratio of dispersion component of SSFE results from the neutrality of the crystal surface of alkali halide. Lattice component of alkali halide is 780, 717 and 689 kJ&#183mol-1 for NaCl, KCl, and KBr. The larger lattice enthalpy decreases dispersion component, and increases polar component of the SSFE. The larger lattice enthalpy is considered to enhance the rumpling of the crystal surface more strongly, and such rumpling is considered to decrease the neutrality of the crystal surface. 展开更多
关键词 COMPONENT Specific Surface free Energy Crystal growth MINERAL Salt Morphology
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Why Free Will Is Logically Not Possible within Naturalism
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作者 Michael Prost 《Journal of Philosophy Study》 2017年第2期100-109,共10页
One of the most intriguing problems of philosophy and of mankind is the question whether humans have a free will. This question is heavily disputed between natural scientists and especially neuroscientists, who deny f... One of the most intriguing problems of philosophy and of mankind is the question whether humans have a free will. This question is heavily disputed between natural scientists and especially neuroscientists, who deny free will, and philosophers and other groups, who insist on free will. It is perplexing that both sides base their premise on the same precondition, namely naturalism. We will prove that naturalism automatically leads to physicalism, to materialism, and to reductionism. We will also prove here that it is logically not possible to have a free will if naturalism is true. Free will definitely requires an additional substance, a non-material soul, which cannot be part of our universe. This must not be in contradiction to our current knowledge of natural sciences. 展开更多
关键词 free will NATURALISM physical realization of will decisions determinism/indeterminism compatibilism libertarianism
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Notions of Free Market and Social Welfare in Islamic Economics
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作者 Sajid Puthenpeedikayil 《Journal of Modern Accounting and Auditing》 2015年第9期476-486,共11页
Trading and business in Islam has been identified as the second best profession after agriculture and Prophet Muhammad (PBUH) himself has been engaged in trading. The Islamic theory of market aims to provide optimiz... Trading and business in Islam has been identified as the second best profession after agriculture and Prophet Muhammad (PBUH) himself has been engaged in trading. The Islamic theory of market aims to provide optimization of returns and satisfaction for all stakeholders. It also seeks to make "free market" an instrument of promoting equity and social justice for the welfare of society. It combines tenants from the free market model as well as those in command market economy. Islamic economics identifies certain functional parameters for the efficient functioning of the market to achieve the optimization of returns and social welfare like absence of middle men, prohibition of hoarding, mode of finance free from interest and usury, taxation and other wealth redistribution instruments like Zakat and Khums, asset-based and risk-sharing partnerships and stakes, etc.. It essentially creates conditions for proper functioning of a competitive market as an instrument of economic progress and social equity. In Islamic economics, the role accorded to the state is to ensure that institutions are set up and vigilance officers are appointed which create the specified condition for the proper and fair functioning of the market and hence preventing what is identified as "market failure". The role of the state is to improve the functioning of the market as opposed to that of systematic intervention. This paper tries to examine the Islamic notions of "free market" in the traditional sources like Qur'an, Hadees, the early texts of Islamic Jurisprudence, and contemporary writings on Islamic economic system and to make a comparative analysis with theories of market in capitalist and socialist frameworks. The paper will examine the extent to which Islamic notions of free market offer an alternative model to resolve the problems of growth, inequity, and risk management. 展开更多
关键词 optimization of returns free market and social welfare inclusive growth
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Milk Replacer Acidification for Free-Access Feeding: Effects on the Performance and Health of Veal Calves 被引量:1
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作者 Cynthia G. Todd Ken E. Leslie +5 位作者 Suzanne T. Millman Jan M. Sargeant Heather Migdal Kathleen Shore Neil G. Anderson Trevor J. DeVries 《Open Journal of Animal Sciences》 2016年第3期234-246,共13页
Objectives of this study were to investigate the effects of milk replacer (MR) acidification for free- access feeding on pre- and post-weaning performance, morbidity and mortality of calves. Calves were randomly assig... Objectives of this study were to investigate the effects of milk replacer (MR) acidification for free- access feeding on pre- and post-weaning performance, morbidity and mortality of calves. Calves were randomly assigned to free-access feeding of acidified (ACID, n = 31) or non-acidified (NON, n = 31) MR, and weaned at 42 days. ACIDMR was prepared to pH 4.0 - 4.5 using formic acid. Intakes were measured daily and weights weekly. Samples of ACID and NON MR were analyzed for coliform and aerobic bacterial growth. After weaning, calves transitioned to a grain-fed veal diet, weighed every 2 weeks. At slaughter (approximately 6 months of age), lungs were evaluated for gross pathological changes and dressed carcass weights were obtained. Generalized linear mixed models were constructed to examine the effects of MR acidification. Differences by treatment group for pre- and post-weaning morbidity and mortality were tested using Pearson’s χ2 and Fisher’s exact tests. ACID calves consumed less MR than NON (10.6 vs. 11.7 L/d, P = 0.02). Acidification tended to promote earlier onset of starter ration consumption (32.0 vs. 39.5 d, hazard ratio = 1.5, P = 0.07), but did not affect average daily starter ration or water intakes across the pre-weaning period. ACID and NON calves did not differ for BW at weaning, pre- or post-weaning ADG or dressed carcass weight. ACID MR had less coliform (P < 0.001) and aerobic bacterial growth (P < 0.001) than NON MR, but odds of disease treatment and mortality did not differ. ACID calves tended to have lower odds of pulmonary lesions during post-mortem inspection than NON calves (OR = 0.3, P = 0.07). These results indicate that under free-access feeding conditions, acidification limited bacterial growth and MR intake, but there were no long-term impacts of acidification on calf performance or health. In conclusion, acidification to pH 4.0 - 4.5 will significantly reduce bacterial growth in milk fed to calves. 展开更多
关键词 Acidified Milk Feeding free-Access Milk Feeding HEALTH growth Veal Calves
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Characteristics of Laser Reflow Bumping of Sn3.5Ag and Sn3.5Ag0.5Cu Lead-Free Solder Balls
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作者 Yanhong TIAN Chunqing WANG Yarong CHEN 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2008年第2期220-226,共7页
ead-free Sn3.5Ag and Sn3.5Ag0.5Cu solder balls were reflowed by laser to form solder bumps. Shear test was performed on the solder bumps, and SEM/EDX (scanning electron microscopy/energy dispersive X-ray spectrometer... ead-free Sn3.5Ag and Sn3.5Ag0.5Cu solder balls were reflowed by laser to form solder bumps. Shear test was performed on the solder bumps, and SEM/EDX (scanning electron microscopy/energy dispersive X-ray spectrometer) was used to analyze the formation of intermetallic compounds (IMCs) at interface region. A finite element modeling on the temperature gradient and distribution at the interface of solder bump during laser reflow process was conducted to elucidate the mechanism of the IMCs growth direction. The results show that the parameters window for laser reflow bumping of Sn3.5Ag0.5Cu was wider than that of Sn3.5Ag. The shear strength of Sn3.5Ag0.5Cu solder bump was comparable to that of Sn3.5Ag solder bump, and was not affected obviously by laser power and irradiation time when appropriate parameters were used. Both laser power and heating time had a significant effect on the formation of IMCs. A continuous AuSn4 intermetallic compound layer and some needle-like AuSn4 were observed at the interface of solder and Au/Ni/Cu metallization layer when the laser power is small. The formation of needle-like AuSn4 was due to temperature gradient at the interface, and the direction of temperature gradient was the preferred growth direction of AuSn4. With increasing the laser power and heating time, the needle-like AuSn4 IMCs dissolved into the bulk solder, and precipitated out once again during solidification along the grain boundary of the solder bump. 展开更多
关键词 Lead-free bumping Laser reflow Intermetallic compound growth
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Effects of aligning pulse duration on the degree and the slope of nitrogen field-free alignment
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作者 王翡 蒋红兵 龚旗煌 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第5期288-293,共6页
Through theoretical analysis,we show how aligning pulse durations affect the degree and the time-rate slope of nitrogen field-free alignment at a fixed pulse intensity.It is found that both the degree and the slope fi... Through theoretical analysis,we show how aligning pulse durations affect the degree and the time-rate slope of nitrogen field-free alignment at a fixed pulse intensity.It is found that both the degree and the slope first increase,then saturate,and finally decrease with the increasing pump duration.The optimal durations for the maximum degree and the maximum slope of the alignment are found to be different.Additionally,they are found to mainly depend on the molecular rotational period,and are affected by the temperature and the aligning pump intensities.The mechanism of molecular alignment is also discussed. 展开更多
关键词 field-free molecular alignment femtosecond phenomenon strong filed physics
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Developments in the Turkish Economy During the Period Between 2000-2010 in the Light of the Free-market Economy Policies of the 1980s and 1990s
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作者 SıtkıSelim Dolanay 《Economics World》 2024年第4期165-179,共15页
The structural changes that took place in the Turkish Economy following the January 24,1980 decisions and their aftermath.With the policies of opening up to the outside world and transition to a free market economy in... The structural changes that took place in the Turkish Economy following the January 24,1980 decisions and their aftermath.With the policies of opening up to the outside world and transition to a free market economy in the 1980s in the Turkish Economy,there were radical changes in the structure of the economy and the prices of all goods and services began to be determined by the market under market conditions.In the 1980s,which can be called the transition period to the Free Market Economy and open economy,efforts were made to privatize state institutions and determine the prices of goods and services under free market conditions in order to withdraw the state from economic life,while on the other hand,efforts were made to grant freedom to foreign trade.While these two main issues were being realized,the import substitution industrialization strategy was abandoned and the export-oriented growth model was started to be implemented.The last step of this opening up and liberalization process was realized with the decision number 32 in 1989.We can say that with the liberalization of capital movements in the 1990s,economic growth and development were tried to be achieved through hot money inflows rather than direct foreign investments.This trend made the economy more open to crises,and for the first time,a crisis occurred in the form of the 1994 economic crisis,which was understood to be caused by hot money.The 1994 economic crisis was tried to be overcome by providing state guarantees to bank deposits and applying high interest rates.Thus,it is noteworthy that high inflation was experienced in the period until the 2001 economic crisis.We can say that the financial crisis that occurred in 2001 as a result of the environment that occurred in the 1990s deepened and turned into an economic crisis,and the economic and political effects of this crisis were experienced.Although there have been many economic crises in the history of the Republic,this crisis is considered to be the most deeply effective.While the crisis was overcome with the stand by agreement made with the IMF and the announced Transition to a Strong Economy program,the economy started to grow rapidly with the ease of using foreign resources,and political stability seems to have enabled this economic growth process to continue uninterruptedly except 2009.There was also a decrease in inflation rates. 展开更多
关键词 Turkish economy free market economy import export investments economic growth inflation
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