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Bone marrow-derived mesenchymal stem cell transplantation attenuates overexpression of inflammatory mediators in rat brain after cardiopulmonary resuscitation 预览
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作者 Qing-Ming Lin Xia-Hong Tang +2 位作者 Shi-Rong Lin Ben-Dun Chen Feng Chen 《中国神经再生研究:英文版》 SCIE CAS CSCD 2020年第2期324-331,共8页
Emerging evidence suggests that bone marrow-derived mesenchymal stem cell transplantation improves neurological function after cardiac arrest and cardiopulmonary resuscitation;however, the precise mechanisms remain un... Emerging evidence suggests that bone marrow-derived mesenchymal stem cell transplantation improves neurological function after cardiac arrest and cardiopulmonary resuscitation;however, the precise mechanisms remain unclear. This study aimed to investigate the effect of bone marrow-derived mesenchymal stem cell treatment on expression profiles of multiple cytokines in the brain after cardiac arrest and cardiopulmonary resuscitation. Cardiac arrest was induced in rats by asphyxia and cardiopulmonary resuscitation was initiated 6 minutes after cardiac arrest. One hour after successful cardiopulmonary resuscitation, rats were injected with either phosphate-buffered saline(control) or 1 × 10~6 bone marrow-derived mesenchymal stem cells via the tail vein. Serum S100 B levels were measured by enzyme-linked immunosorbent assay and neurological deficit scores were evaluated to assess brain damage at 3 days after cardiopulmonary resuscitation. Serum S100 B levels were remarkably decreased and neurological deficit scores were obviously improved in the mesenchymal stem cell group compared with the phosphate-buffered saline group. Brains were isolated from the rats and expression levels of 90 proteins were determined using a RayBio Rat Antibody Array, to investigate the cytokine profiles. Brain levels of the inflammatory mediators tumor necrosis factor-α, interferon-γ, macrophage inflammatory protein-1α, macrophage inflammatory protein-2, macrophage inflammatory protein-3α, macrophage-derived chemokine, and matrix metalloproteinase-2 were decreased ≥ 1.5-fold, while levels of the anti-inflammatory factor interleukin-10 were increased ≥ 1.5-fold in the mesenchymal stem cell group compared with the control group. Donor mesenchymal stem cells were detected by immunofluorescence to determine their distribution in the damaged brain, and were primarily observed in the cerebral cortex. These results indicate that bone marrow-derived mesenchymal stem cell transplantation attenuates brain damage induced by cardiac arrest and 展开更多
关键词 antibody array ASPHYXIA brain damage cardiac arrest CARDIOPULMONARY RESUSCITATION global cerebral ischemia inflammatory mediator mesenchymal stem cell NEUROLOGICAL DEFICIT score S100B
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RAID 4SMR:RAID Array with Shingled Magnetic Recording Disk for Mass Storage Systems
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作者 Quoc Le Ahmed Amer JoAnne Holliday 《计算机科学技术学报:英文版》 SCIE EI CSCD 2019年第4期854-868,共15页
One way to increase storage density is using a shingled magnetic recording(SMR)disk.We propose a novel use of SMR disks with RAID(redundant array of independent disks)arrays,specifically building upon and compared wit... One way to increase storage density is using a shingled magnetic recording(SMR)disk.We propose a novel use of SMR disks with RAID(redundant array of independent disks)arrays,specifically building upon and compared with a basic RAID 4 arrangement.The proposed scheme(called RAID 4SMR)has the potential to improve the performance of a traditional RAID 4 array with SMR disks.Our evaluation shows that compared with the standard RAID 4,when using update in-place in RAID arrays,RAID 4SMR with garbage collection not just can allow the adoption of SMR disks with a reduced performance penalty,but offers a performance improvement of up to 56%. 展开更多
关键词 DISK ARRAY REDUNDANT ARRAY of independent disks(RAID) shingled magnetic recording(SMR) shingled write
Dot-shaped beamforming analysis of subarray-based sin-FDA
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作者 Bo WANG Jun-wei XIE +1 位作者 Jing ZHANG Jia-ang GE 《信息与电子工程前沿:英文版》 SCIE EI CSCD 2019年第10期1429-1444,共16页
Phased array (PA) radar is one of the most popular types of radar. In contrast to PA, the frequency diverse array (FDA) is a potential solution to suppress range-related interference because of its time-range-angle-de... Phased array (PA) radar is one of the most popular types of radar. In contrast to PA, the frequency diverse array (FDA) is a potential solution to suppress range-related interference because of its time-range-angle-dependent beampattern. However, the range-angle coupling inherent in the FDA transmit beampattern may degrade the output signal-to-interference-plus-noise ratio (SINR). We propose a dot-shaped beamforming method based on the analyzed four subarray-based FDAs and subarray-based planar FDAs using a sinusoidally increasing frequency offset with elements transmitting at multiple frequencies. The numerical results show that the proposed approach outperforms the existing log-FDA with logarithmical frequency offset in transmit energy focus, sidelobe suppression, and array resolution. Comparative simulation results validate the effectiveness of the proposed method. 展开更多
关键词 Frequency diverse array Subarray-based frequency diverse array Decoupling Dot-shaped beamforming
Estimation of Shear Wave Structure and Horizontal to Vertical Spectral Ratio at Different Sites in Kathmandu Valley 预览
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作者 Srijana Poudel Subesh Ghimire 《地球科学和环境保护期刊(英文)》 2019年第5期300-308,共9页
The present study was carried out to evaluate resonant frequency of the ground and to characterize subsurface ground based on shear wave velocity structure. For this, five sites were selected such as Pulchowk, Chhauni... The present study was carried out to evaluate resonant frequency of the ground and to characterize subsurface ground based on shear wave velocity structure. For this, five sites were selected such as Pulchowk, Chhauni, Gaushala, Buddhanagar and Bhainsepati. About 20 data were recorded in each site and then shear wave velocity structure and graph of amplification ratio with their spatial distribution has been established with the help of software i.e. Seisimager/Seismodule Controller. The results of both analysis methods were then compared to the amplitude of the Gorkha Earthquake and borehole data. All these data and study indicates that the Kathmandu Valley sediments are dependent on the frequency of the seismic waves and the wave velocity is greater in the peripheral region than in the central part of the Valley. The result had also shown that the presence of silty-sand, clay and loose gravel soil with low bearing capacity and elastic modulus in most of the sites are responsible for devastation. It was also noted that apart from few limitations, a non-intrusive microtremor analysis can be adopted for earthquake site characterization in the Kathmandu Valley which can be readily applied and expanded upon in future seismic hazard and microzonation efforts for Kathmandu. 展开更多
关键词 MICROTREMOR PASSIVE Source Array BOREHOLE MICROZONATION
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MEMS矢量水听器阵列的仿真与实验研究 预览
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作者 冯飞 《指挥控制与仿真》 2019年第5期108-110,共3页
针对6阵元的MEMS矢量水听器阵增益和波束指向性图性能进行了理论分析与仿真,给出仿真所采用的理论、公式、各项参数与结论。并进行了相应实验验证,结果表明在阵列总长度较小的情况下其阵增益和波束宽度具有较好的一致性。
关键词 MEMS矢量水听器 阵列 阵增益 波束宽度
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Dynamically Tunable Perfect Absorbers Utilizing Hexagonal Aluminum Nano-Disk Array Cooperated with Vanadium Dioxide
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作者 周鹏 郑改革 +2 位作者 陈云云 咸冯林 徐林华 《中国物理快报:英文版》 SCIE CAS CSCD 2019年第1期19-23,共5页
A tunable perfect absorber composed of hexagonal-arranged aluminum nano-disk array embedded in the vanadium dioxide (VO2)film is proposed.The aim is to achieve the tunability of resonance absorption peak in the visibl... A tunable perfect absorber composed of hexagonal-arranged aluminum nano-disk array embedded in the vanadium dioxide (VO2)film is proposed.The aim is to achieve the tunability of resonance absorption peak in the visible and near-infrared regimes.Numerical results reveal that the absorption peak achieves a large tunability of 76.6% while VO2 undergoes a structural transition from insulator phase to metallic phase.By optimizing the structural parameters,an average absorption of 95% is achieved from 1242 to 1815nm at the metallic phase state.In addition,the near unity absorption can be fulfilled in a wide range of incident angle (0°-60°)and under all polarization conditions.The method and results presented here would be beneficial for the design of active optoelectronic devices. 展开更多
关键词 VANADIUM Dioxide HEXAGONAL ALUMINUM nanodisc array ABSORBENT
用于经颅磁刺激预测量的三维磁场传感器阵列设计
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作者 熊慧 罗小慧 刘近贞 《航天医学与医学工程》 CAS CSCD 北大核心 2019年第4期351-357,共7页
目的基于电磁感应原理,提出一种三维磁场传感器阵列,用于评估经颅磁刺激(TMS)线圈产生的磁场分布。方法将大脑简化为4层的长方体结构,每层放置24、24、20、20个传感器,以此设计三维磁场传感器阵列的结构,并根据法拉第电磁感应定律标定... 目的基于电磁感应原理,提出一种三维磁场传感器阵列,用于评估经颅磁刺激(TMS)线圈产生的磁场分布。方法将大脑简化为4层的长方体结构,每层放置24、24、20、20个传感器,以此设计三维磁场传感器阵列的结构,并根据法拉第电磁感应定律标定传感器系数。验证三维磁场传感器的精确度和稳定性,并对由88个三维传感器组成的阵列结构实施测试。结果三维磁场传感器测量精度为0.99%;间隔10个月进行4次测量,后3次测量结果与第一次测量结果的相对误差均在0.5%以下,且三维磁场传感器阵列能够准确测出空间磁场的分布情况。88个点的测量结果与有限元分析结果的相对误差平均值约为1%。结论本文设计的三维磁场传感器阵列为评估TMS线圈磁场分布提供了一种切实可行的新方法,有助于提高TMS的安全性。 展开更多
关键词 三维磁场传感器 标定 阵列 TMS预测量
Optically controlled phase array antenna [Invited]
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作者 石暖暖 李伟 +1 位作者 祝宁华 李明 《中国光学快报:英文版》 SCIE EI CAS CSCD 2019年第5期72-77,共6页
To overcome the beam squint in wide instantaneous frequency, we review a number of system-level optical controlled phase array antennas for beam forming. The optical delay net work based on a fiber device in terms of ... To overcome the beam squint in wide instantaneous frequency, we review a number of system-level optical controlled phase array antennas for beam forming. The optical delay net work based on a fiber device in terms of topological structure of an Mbit optical switch, fiber grating, high-dispersion fiber, and vector-sum technology is discussed, respectively. Lastly, an integrated circuit is simply summarized. 展开更多
关键词 Optically CONTROLLED PHASE ARRAY ANTENNA WIDE instantaneous FREQUENCY
Visual Basic处理多财务数据Excel表格 预览
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作者 胡敏 李梅 郑增国 《现代计算机》 2019年第5期97-100,共4页
在我校财务报销Excel表格中存在一些不规范格式和姓名,人工手动的方法会造成时间以及资源的浪费并影响数据提取的准确。为了避免这种现象,根据实际工作阐述使用Visual Basic的特性,运用数组对多个Excel进行同时处理的过程,充分发挥VB编... 在我校财务报销Excel表格中存在一些不规范格式和姓名,人工手动的方法会造成时间以及资源的浪费并影响数据提取的准确。为了避免这种现象,根据实际工作阐述使用Visual Basic的特性,运用数组对多个Excel进行同时处理的过程,充分发挥VB编程的快捷和计算机处理的准确以提高效率。 展开更多
关键词 VISUAL Basic EXCEL 数组
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Efficient Signal Separation Method Based on Antenna Arrays for GNSS Meaconing
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作者 Jiaqi Zhang Xiaowei Cui +2 位作者 Hailong Xu Sihao Zhao Mingquan Lu 《清华大学学报自然科学版(英文版)》 EI CAS CSCD 2019年第2期216-225,共10页
As an effective deceptive interference technique for military navigation signals,meaconing can be divided into two main types:those that replay directly and those that replay after signal separation.The latter can add... As an effective deceptive interference technique for military navigation signals,meaconing can be divided into two main types:those that replay directly and those that replay after signal separation.The latter can add different delays to each satellite signal and mislead the victim receiver with respect to any designated position, thus has better controllability and concealment capability.A previous study showed there to be two main spatial processing techniques for separating military signals,whereby either multiple large-caliber antennas or antenna arrays are used to form multiple beams that align with all visible satellites.To ensure sufficient spatial resolution, the main lobe width of the antenna or beam must be sufficiently narrow,which requires the use of a large antenna aperture or a large number of array elements.In this paper,we propose a convenient and effective signal separation method,which is based on an antenna array with fewer elements.While the beam of the array is pointing to a specified satellite,the other satellite signals are regarded as interference and their power is suppressed to a level below the receiver's sensitivity.With this method,the number of array elements depends only on the number of visible satellites,thus greatly reducing the hardware cost and required processing capacity. 展开更多
关键词 GNSS meaconing ANTENNA ARRAY BEAMFORMING SIGNAL SEPARATION
A Novel Method for PIT Effects Based on Plasmonic Decoupling
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作者 孙斌 谢飞凤 +2 位作者 康帅 杨友昌 刘坚强 《中国物理快报:英文版》 SCIE CAS CSCD 2019年第1期75-79,共5页
A tunable dual-band stop-band THz spectrum can be realized in a hybrid structure,which consists of metal nanoribbon arrays clad by graphene nanoribbons.Dual-band spectra can be controlled separately by the nanoribbon ... A tunable dual-band stop-band THz spectrum can be realized in a hybrid structure,which consists of metal nanoribbon arrays clad by graphene nanoribbons.Dual-band spectra can be controlled separately by the nanoribbon width w and graphene chemical potential μc.We explain that two local plasmonic modes excited at graphene ribbons belong to different gratings,which uncouple with each other by electro-magnetic shielding of the metal ribbons.Furthermore,plasmonic induced transparent (PIT)effects can also be realized by making the two transmission notches close to each other,with better performance than the PIT system based on plasmonic coupling, such as with a larger extinction radio and a tunable transparency window. 展开更多
关键词 Plasma DECOUPLING Nuclear effect analysis method Metal NANORIBBON ARRAY
压缩感知波束形成算法性能分析 预览
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作者 魏娟 孙健 +2 位作者 邵丁 闫豪 李争光 《噪声与振动控制》 CSCD 2019年第4期81-84,124共5页
波束形成声源识别技术具有测量速度快、计算效率高等优点,被广泛应用。因为其“主瓣”过宽造成空间定位精度低,“旁瓣”既高又多导致出现许多“鬼影”声源,从而限制其得到进一步应用。为解决以上问题,利用压缩感知理论中贪婪算法对信号... 波束形成声源识别技术具有测量速度快、计算效率高等优点,被广泛应用。因为其“主瓣”过宽造成空间定位精度低,“旁瓣”既高又多导致出现许多“鬼影”声源,从而限制其得到进一步应用。为解决以上问题,利用压缩感知理论中贪婪算法对信号的重建方法,改进常规波束形成算法,提出一种压缩感知波束形成方法。对单极子声源和相干声源进行声源识别数值模拟仿真,结果表明:与函数波束形成方法相比,压缩感知波束形成方法在识别单极子声源和相干声源时,定位精度更高,更能使旁瓣得到有效衰减,分辨率提升更大,并能够大幅缩短识别时间,具有一定的研究意义。 展开更多
关键词 振动与波 波束形成 压缩感知 贪婪算法 阵列 分辨率
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Study on volt-ampere characteristics of solar array arcs in LEO spacecraft
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作者 朱立颖 刘治钢 +3 位作者 张晓峰 王超 李小飞 赵冰欣 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第2期39-46,共8页
The primary and secondary arcs volt-ampere characteristics of low earth orbit solar arrays are studied in this research. Using three gallium-arsenide solar cell samples, the gap lengths of the solar cell are set to 1,... The primary and secondary arcs volt-ampere characteristics of low earth orbit solar arrays are studied in this research. Using three gallium-arsenide solar cell samples, the gap lengths of the solar cell are set to 1, 2, and 3 mm. First, the primary arc voltage characteristics of a solar array are analyzed. It is found that two steps are involved in the primary arc voltages, which are 116 and 22 V according to our experiment and are independent of the electrostatic discharge current and the gap lengths. By comparing with the arc pattern, we determined that current chopping may be the reason for the stepped arc voltage. Then, the characteristics of the secondary arc of the solar array are demonstrated. The study shows that the secondary arc voltage values increase with the gap length. In the case of the same cell with a fixed gap length, the voltage of the secondary arc increases with the string current. Finally, the relationship between the secondary arc voltage and the gap length is obtained which helps the string voltage and the gap length selection for system design. 展开更多
关键词 primary ARC SECONDARY ARC solar ARRAY
A Novel Multi-Points Laser Monitoring of Building Settlement and Its Risk Evaluation
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作者 CHAI Caiping WU Zejian +5 位作者 WANG Huifeng GUAN Limin HUANG He MU Kenan CUI Wenfen HAO Ting 《武汉大学学报:自然科学英文版》 CAS CSCD 2019年第5期442-454,共13页
Aiming at the defects of routine settlement measurement methods, such as complicated procedures, time-consuming and labor-intensive, high cost and low measurement accuracy, based on the analysis of existing engineerin... Aiming at the defects of routine settlement measurement methods, such as complicated procedures, time-consuming and labor-intensive, high cost and low measurement accuracy, based on the analysis of existing engineering measurement technical requirements and specifications, a multi-point high precision and high efficiency based on laser reference is proposed. The automatic building settlement real-time monitoring system program gives the principle and system model of single-point settlement observation. The model of multi-point scanning settlement monitoring system and the model of multi-point network settlement monitoring system are designed, and their advantages and disadvantages are analyzed. We focus on the networked multi-point settlement monitoring system for network cumulative error analysis, and propose related evaluation and correction methods. The hardware schematic and software block diagram of the laser reference measurement and measurement system of the single point settlement acquisition system are given. Finally, the risk of subsidence state is quantitatively evaluated based on multi-point settlement monitoring data. The measurement error of this method is less than 300 μm, which can realize the monitoring and evaluation of the overall settlement. 展开更多
关键词 measurement technology LASER REFERENCE SETTLEMENT CHAIN linear ARRAY Charge-Coupled Device(CCD)
Thermal resistance matrix representation of thermal effects and thermal design of microwave power HBTs with two-dimensional array layout
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作者 陈蕊 金冬月 +5 位作者 张万荣 王利凡 郭斌 陈虎 殷凌寒 贾晓雪 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第9期373-380,共8页
Based on the thermal network of the two-dimensional heterojunction bipolar transistors(HBTs) array, the thermal resistance matrix is presented, including the self-heating thermal resistance and thermal coupling resist... Based on the thermal network of the two-dimensional heterojunction bipolar transistors(HBTs) array, the thermal resistance matrix is presented, including the self-heating thermal resistance and thermal coupling resistance to describe the self-heating and thermal coupling effects, respectively.For HBT cells along the emitter length direction, the thermal coupling resistance is far smaller than the self-heating thermal resistance, and the peak junction temperature is mainly determined by the self-heating thermal resistance.However, the thermal coupling resistance is in the same order with the self-heating thermal resistance for HBT cells along the emitter width direction.Furthermore, the dependence of the thermal resistance matrix on cell spacing along the emitter length direction and cell spacing along the emitter width direction is also investigated, respectively.It is shown that the moderate increase of cell spacings along the emitter length direction and the emitter width direction could effectively lower the self-heating thermal resistance and thermal coupling resistance,and hence the peak junction temperature is decreased, which sheds light on adopting a two-dimensional non-uniform cell spacing layout to improve the uneven temperature distribution.By taking a 2 × 6 HBTs array for example, a twodimensional non-uniform cell spacing layout is designed, which can effectively lower the peak junction temperature and reduce the non-uniformity of the dissipated power.For the HBTs array with optimized layout, the high power-handling capability and thermal dissipation capability are kept when the bias voltage increases. 展开更多
关键词 HETEROJUNCTION BIPOLAR transistors(HBTs) ARRAY THERMAL effects THERMAL resistance matrix THERMAL design
Investigation of the Vibration Behavior of Fluidelastic Instability in Closely Packed Square Tube Arrays 预览
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作者 WeiTan HaoWu Guorui Zhu 《天津大学学报:英文版》 EI CAS 2019年第2期124-142,共19页
Flow-induced vibrations in heat exchanger tubes have led to numerous accidents and economic losses in the past. Fluidelastic instability is the most critical flow-induced vibration mechanism in heat exchangers. Both e... Flow-induced vibrations in heat exchanger tubes have led to numerous accidents and economic losses in the past. Fluidelastic instability is the most critical flow-induced vibration mechanism in heat exchangers. Both experimental and computational studies conducted to determine fluidelastic instability were presented in this paper. In the experiment, a water channel was built, and aclosely packed normal square tube array with a pitch-to-diameter ratio of 1.28 was tested, and signifi cant fluidelastic instability was observed. A numerical model adopting large-eddy simulation and moving mesh was established using ANSYS CFX, and results showed good agreement with the experimental findings. The vibration behaviors of fluidelastic instability were discussed, and results showed that the dominant vibration direction of the tubes changed from streamwise to transverse beyond a critical velocity. A 180° phaselag between adjacent tubes was observed in both the experiment and simulations. Normal and rotated square array cases with pitch-to-diameter ratios of 1.28 and 1.5 were also simulated. The results of this study provide better insights into the vibration characteristics of a square tube array and will help improve the fundamental research and safety design of heat exchangers. 展开更多
关键词 Fluidelastic INSTABILITY DOMINANT vibration direction Phase LAG SQUARE tube ARRAY Heat EXCHANGER
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Dislocation neutralizing in a self-organized array of dislocation and anti-dislocation
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作者 邓凤麟 胡湘生 王少峰 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第11期251-257,共7页
A one-dimensional(1 D) self-organized array composed of dislocation and anti-dislocation is analytically investigated in the frame of Peierls theory. From the exact solution of the Peierls equation, it is found that t... A one-dimensional(1 D) self-organized array composed of dislocation and anti-dislocation is analytically investigated in the frame of Peierls theory. From the exact solution of the Peierls equation, it is found that there exists strong neutralizing effect that makes the Burgers vector of each individual dislocation in the equilibrium array smaller than that of an isolated dislocation. This neutralizing effect is not negligible even though dislocations are well separated. For example, when the distance between the dislocation and the anti-dislocation is as large as ten times of the dislocation width, the actual Burgers vector is only about 80% of an isolated dislocation. The neutralizing effect originates physically from the power-law asymptotic behavior that enables two dislocations interfere even though they are well separated. 展开更多
关键词 dislocation array NEUTRALIZING exact solution
Co-location of QTL for Sclerotinia stem rot resistance and flowering time in Brassica napus 预览
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作者 Jian Wu Peipei Chen +6 位作者 Qing Zhao Guangqin Cai Yue Hu Yang Xiang Qingyong Yang Youping Wang Yongming Zhou 《作物学报:英文版》 CAS CSCD 2019年第2期227-237,共11页
Sclerotinia stem rot (SSR) caused by Sclerotinia sclerotiorum (Lib.) de Bary is one of the most devastating diseases of Brassica napus worldwide.Both SSR resistance and flowering time (FT) adaptation are major breedin... Sclerotinia stem rot (SSR) caused by Sclerotinia sclerotiorum (Lib.) de Bary is one of the most devastating diseases of Brassica napus worldwide.Both SSR resistance and flowering time (FT) adaptation are major breeding goals in B.napus.However,early maturing rapeseed varieties,which are important for rice-rapeseed rotation in China,are often highly susceptible to SSR.Here,we found that SSR resistance was significantly negatively correlated with FT in a natural population containing 521 rapeseed inbred lines and a double haploid (DH) population with 150 individual lines,both of which had great variation in FT.Four chromosomal regions on A2,A6,C2,and C8 affecting both SSR resistance and FT were identified using quantitative trait loci (QTL) mapping after constructing a high-density genetic map based on single nucleotide polymorphism markers in the DH population.Furthermore,we aligned QTL for the two traits identified in the present and previous studies to the B.napus reference genome,and identified four colocalized QTL hotspots of SSR resistance and FT on A2 (0–7.7 Mb),A3 (0.8–7.5 Mb),C2 (0–15.2 Mb),and C6 (20.2–36.6 Mb).Our results revealed a genetic link between SSR resistance and FT in B.napus,which should facilitate the development of effective strategies in both early maturing and SSR resistance breeding and in map-based cloning of SSR resistance QTL. 展开更多
关键词 SCLEROTINIA stem ROT Brassica NAPUS QTL mapping FLOWERING time SNP array
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一维ZnO纳米材料的制备技术研究 预览
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作者 夏世钦 王静 +4 位作者 刘新儒 马凯 赵晨媚 吴丽冰 张正国 《生物化工》 2019年第2期99-101,104共4页
ZnO是一种良好的半导体材料,可以很容易通过形貌的控制以及金属和非金属离子掺杂而获得更佳的光电性质。ZnO的导电性比TiO2高几个数量级,有利于电子的快速传输,在低温下易于溶解处理,具有较稳定的结构,而且可以应用不同的技术制备成各... ZnO是一种良好的半导体材料,可以很容易通过形貌的控制以及金属和非金属离子掺杂而获得更佳的光电性质。ZnO的导电性比TiO2高几个数量级,有利于电子的快速传输,在低温下易于溶解处理,具有较稳定的结构,而且可以应用不同的技术制备成各种形貌,如纳米棒、纳米片等。与传统ZnO粉体相比,一维的ZnO纳米材料具有较高的长径比、更高的电子密度和较低的功函数,在太阳能电池、光催化领域有着重要应用前景。为研究易于制备、成本较低的ZnO纳米材料制备技术,详细列举和对比了较成熟的7种ZnO纳米材料的制备技术,为以上研究领域学者提供参考。 展开更多
关键词 ZNO 纳米棒 阵列 制备
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Mechanism of brittle fracture in diamond turning of microlens array on polymethyl methacrylate
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作者 Tian-Feng Zhou Ben-Shuai Ruan +3 位作者 Jia Zhou Xiao-Bin Dong Zhi-Qiang Liang Xi-Bin Wang 《先进制造进展:英文版》 CAS CSCD 2019年第2期228-237,共10页
Diamond cutting is a popular method to fabricate microlens array (MLA) on polymethyl methacrylate (PMMA);however, it is limited by brittle fracture, which is formed easily on the surface of MLA during the cutting proc... Diamond cutting is a popular method to fabricate microlens array (MLA) on polymethyl methacrylate (PMMA);however, it is limited by brittle fracture, which is formed easily on the surface of MLA during the cutting process. In this paper, the formation mechanism of the brittle fracture is studied via a series of experiments including the slow tool servo (STS) cutting experiment of MLA, surface scratching experiment and suddenstop cutting experiment. The effects of undeformed chip thickness, feed rate, and machining track on brittle fracture formation are investigated in detail. In addition, based on the fracture formation mechanism, a bi-directional cutting approach is proposed to eliminate the regional brittle fracture of the microlens during diamond cutting. An experiment was then conducted to verify the method;the results demonstrated that bi-directional cutting could eliminate brittle fracture entirely. Finally, a spherical MLA with the form error (vPV) of 60 nm and the surface roughness (Ra) of 8 nm was successfully fabricated. 展开更多
关键词 MICROLENS ARRAY (MLA) Polymethyl METHACRYLATE (PMMA) BRITTLE FRACTURE Bi-directional CUTTING
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