HYDROTHERMAL SYNTHESIS AND MAGNETIC PROPERTIES OF NANOSIZED NICKEL ZINC FERRITE POWDER

用水热法分别在200℃和220℃下反应5h制备了纳米级镍锌铁氧体(Ni0.5Zn0.5Fe2O4)粉体。用X射线衍射(X-ray diffraction,XRD)分析合成的纳米Ni0.5Zn0.5Fe2O4的物相,结果表明:200℃水热反应5h得到的纳米Ni0.5Zn0.5Fe2O4粉体中含有γ-Fe2O3,220℃水热反应5h可以得到纯纳米Ni0.5Zn0.5Fe2O4粉体。用透射电镜(transmission electronmicroscope,TEM)、Mssbauer谱(Mssbauer spectroscopy,MS)、Fourier红外分析(Fourier transform infrared spectroscopy,FTIR)、振动样品磁强计(vibrating sample magnetometer,VSM)等方法表征纯纳米Ni0.5Zn0.5Fe2O4粉体。TEM结果表明:纳米Ni0.5Zn0.5Fe2O4粉体粒子为球形,粒径约为20nm。室温MS结果表明:大部分纳米Ni0.5Zn0.5Fe2O4粉体粒子表现出铁磁性,少量的表现出超顺磁性。FTIR分析表明:样品在577cm-1和420cm-1处出现NiZn铁氧体的特征峰。磁滞回线结果表明:纳米Ni0.5Zn0.5Fe2O4粉体粒子的饱和磁化强度为38.14A?m2/kg,剩磁为17.32A?m2/kg,矫顽力为29275.29A/m。Nanosized nickel zinc ferrite(Ni0.5Zn0.5Fe2O4)powder was synthesized by the hydrothermal synthesis method at 200℃ and 220 ℃for 5h,respectively.An X-ray diffraction(XRD)was adopted for the characterization of Ni0.5Zn0.5Fe2O4 powder.It is concluded that the Ni0.5Zn0.5Fe2O4 powder containedγ-Fe2O3 when it is synthesized at 200 ℃for 5h,and pure Ni0.5Zn0.5Fe2O4 powder were prepared by the hydrothermal synthesis at 220 ℃for 5h.The pure powder was characterized by a transmission electron micro-scope(TEM),Mssbauer spectrum(MS),Fourier transform spectroscopy(FTIR),and magnometry using a vibrating sample magne-tometer(VSM).The TEM results show that Ni0.5Zn0.5Fe2O4 nanoparticles are round,and are about 20 nm in diameter.The MS results reveal that most of the Ni0.5Zn0.5Fe2O4 nanoparticles show ferromagnetism and a small quantity of Ni0.5Zn0.5Fe2O4 exhibit superpara-magnetic relaxation.The FTIR results show that the bands at 577 cm-1 and 420 cm-1 are the characteristic bands of NiZn ferrite.The saturated magnetization,remanence and coercivity of Ni0.5Zn0.5Fe2O4 powder are 38.14 A·m2/kg,17.32 A·m2/kg and 29 275.29 A/m,respectively.The powder exhibits good magnetic properties.深圳大学科研(4CHQ)资助项

Co-Ti合金中γ相粗化动力学的实验研究和相场模拟（英文）

本研究结合实验和相场法研究了反相Co-19.7Ti合金中无序γ析出相的组织演变和粗化行为。实验和模拟结果皆表明γ相的形貌随时效时间增加由近球形转变成条状。γ相平均粒径的粗化动力学遵循r~3=kt,可获得如下■texp[-349890RT]。γ相平均粒径随时效时间的变化分为两个阶段,阶段I增长快速而阶段II增长速度减缓。时效温度由700℃增至750℃,γ相粒径分布的峰值变大以及粒径分布的宽度变窄,模拟结果与实验结果取得良好的一致性。National Key R&D Program of China(2017YFB0702901,2016YFB0701401)Ministry of Science and Technology of China(2014DFA53040)Fundamental Research Funds for the Central Universities(20720180072

磷胁迫下豆科作物的基因调控

磷胁迫是全球耕地面临的共性问题。自然资源的局限限制了磷肥的生产,因此植物如何高效利用磷素已经成为研究热点。从基因调控的角度,包括磷胁迫诱导的EST、磷胁迫响应的转录因子、磷胁迫响应的MICRORNA以及植物激素等,综述了植物高效吸收利用磷素的机制

应用于光学系统的压电陶瓷直线电机调焦装置

本发明提供一种应用于光学系统的压电陶瓷直线电机调焦装置。该压电陶瓷直线电机调焦装置，固定部分包括主框架、压电陶瓷电机的定子、以及用于将所述主框架与光学系统的镜筒连接固定的连接板，直线运动部分包括调焦镜组、转接板和压电陶瓷直线电机的动子，调焦镜组安装于主框架内，调焦镜组的镜框的外壁沿透镜轴向固定设置有直线轴承，主框架中固定安装有与所述直线轴承相适配的导轨轴，所述导轨轴与透镜光轴平行；镜框经转接板与压电陶瓷直线电机的动子固定对接，使得调焦镜组能够由动子驱动沿导轨轴移动。该调焦装置具有小型化、重量轻特点，响应快、精度高等动态工作特性优良

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目的:经农杆菌介导将变异链球菌表面蛋白A区与霍乱毒素B亚单位嵌合基因导入黄瓜,获得转基因黄瓜植株,为转基因可食防龋疫苗的研究提供实验基础。方法:利用双元载体pCAMBIA2301构建变异链球菌表面蛋白A区与霍乱毒素B亚单位嵌合质粒(PAcA-ctxB)的植物表达载体p2355-PAcA-CTB;电转化法导入农杆菌EHA105;采用叶盘转化法转化黄瓜,转基因植物经过卡那霉素抗性筛选、GUS基因染色、PCR及Southern blot杂交分析检测目的基因鉴定。结果:成功得到转基因黄瓜植株,卡那霉素抗性筛选、GUS基因染色、PCR及Southern blot杂交分析检测证实目的基因PAcA-ctxB..

Heuristic directional search optimal path algorithm based on the variable raster model(基于变分辨率栅格模型的启发式有向搜索最优路径算法)

针对连续空间中无法直接采用图论方法进行路径分析的问题，提出了基于四叉树思想构建的变分辨栅格模型.该模型不仅兼顾了地形表达精度与数据冗余度，而且避免了地物“边缘效应”的影响.在该模型基础上，设计了一种启发式有向搜索算法，该算法在搜索节点时，首先对相邻节点进行方向性选择，减少搜索空间，提高了算法的效率.实验结果表明，提出的模型及算法不仅能够求得连续空间中的最优路径，而且具有较高的计算效率

MG转轮收集探测系统的检验实验

利用SFC提供的束流对新建的转轮系统进行了检验实验,得到了相关的实验结果.实验证明了该装置的可靠性,为进一步开展超重核的研究完成了预实验

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel