Template‐free synthesis of novel hollow carbon nanospheres with dual active sites as catalyst for fuel cell cathode to improve oxygen reduction reaction performances

A new template‐free controlled method is reported herein to prepare the novel hollow carbon nanospheres with dual active sites of FeN₄ and FeC₃ by in situ growth reaction on graphene nanosheets, labeled as HCN‐FNFCG. As‐prepared HCN‐FNFCG nanomaterials possess hierarchically porous FeN₄/FeC₃ shells with structures of microporous, mesoporous, and macroporous properties. Moreover, the hierarchically porous HCN‐FNFCG nanomaterials with dual active sites of FeN₄ and FeC₃ have not been reported before. The HCN‐FNFCG nanomaterials, as oxygen reduction reaction (ORR) catalysts, are first studied systematically toward cathodic ORR of fuel cell. The measurements have illustrated that HCN‐FNFCG‐650 has the best ORR performances among these HCN‐FNFCG nanomaterials studied. The onset potential of HCN‐FNFCG‐650 has reached 1.095 V in alkaline electrolyte, and its maximum current density is 6.48 mA cm^?2. Additionally, the HCN‐FNFCG‐650 has also displayed small electrochemical impedance, its Tafel‐slope value is 44.25 mV dec^?1, much lower than that of the 20% Pt/C (69.57 mV dec^?1). And its value of current density is still maintained 92.83% of the initial value after 9000‐second continuous tests. High tolerance against methanol crossover is also exhibited for HCN‐FNFCG‐650. This novel method of template‐free synthesis can provide a promising strategy for preparing hollow nanospheres with hierarchically porous shells. And it can be used to design ORR electrocatalysts, electrode materials, or other applications.     

Effect of ripening with Penicillium roqueforti on texture,microstructure, water distribution and volatiles of chicken breast meat

In this study, the influence of ripening with Penicillium roqueforti on texture, microstructure, protein structure, water mobility and volatile flavour compounds of chicken breast meat was investigated. Scanning electron microscopy (SEM) and transmission electron microscope (TEM) images showed that the granule formed and chicken myofibril fractured after ripening. Reduction in α-helix and increases in β-sheet structure content accompanied by decrease in hardness and springiness and increase in gumminess were found in ripened chicken breast meat. Low field nuclear magnetic resonance (LF-NMR) revealed that increasing intra-myofibrillar water and decreasing extra-myofibrillar water resulted in the higher water-holding capacity after ripening with P. roqueforti. In addition, chicken breast meat ripened with P. roqueforti contained more volatile flavour compounds, in particular aldehydes.     

中国原子能科学研究院回旋加速器束流动力学与多物理场模拟技术发展与应用

经过60年的发展，中国原子能科学研究院（CIAE）独立自主地开展了基于PIC技术的强流回旋加速器束流动力学的大规模并行计算的核心算法研究，开发了CYCPIC2D、CYCPIC3D和OPAL-CYCL等强流回旋加速器束流动力学模拟程序，搭建了专用的高性能并行化计算机群PANDA。本文以CIAE已建成及在研的不同类型的回旋加速器为例，总结了回旋加速器基本束流动力学的分析方法和主要计算结果，并介绍了CIAE在回旋加速器束流动力学与多物理场模拟技术方面的发展与应用。     

Improved artificial bee colony algorithm based on escaped foraging strategy

This paper presents an improved artificial bee colony algorithm. Under the framework of the basic artificial bee colony algorithm, this paper redefines the artificial bee colony and introduces search strategies for group escape and foraging based on Levy flight. The proposed algorithm is named artificial bee colony algorithm based on escaped foraging strategy (EFSABC).There are different strategies for scout bees, onlookers, and free bees searching for honey sources in the EFSABC: all working bees relinquish old honey sources due to disturbance, and select different routines to seek new honey sources. Sixteen typical high-dimensional standard functions are used to verify the effectiveness of the proposed algorithm. The EFSABC algorithm outperforms the traditional artificial bee colony algorithm in all aspects.     

高温工作InAlSb的MBE生长及器件性能研究

接近室温的更高工作温度是第三代红外探测器发展的重要方向。本文论述了用MBE在InSb(100)衬底上外延生长制备P-i-N型三元In1-xAlxSb薄膜合金材料,并通过制备单元器件进行了验证。采用RHEED振荡和X射线双晶衍射对In1-xAlxSb薄膜的Al组分进行了调控和检测。5.3 μm厚薄膜的FWHM≈50 arcsec,Al组分约1.9%。10 μm×10 μm原子力表面粗糙度RMS≈0.6 nm。制备的单元器件获得了预期的理想效果,为下一步面阵焦平面的制备奠定了基础。     

采用信道估计法的基站VSWR实时检测

为解决无线基站宽带工作频带内电压驻波比(Voltage Standing Wave Ratio,VSWR)的实时测量，提出了一种采用信道估计法的测量方案。该方案实现简单，在基带处理单元高速率位置发送数据，依次抓取射频通道反馈和反射数据，分别求取信道响应序列，结合工厂装备测试数据，计算驻波反射系数和反射点位置。发送信号采用宽带正交频分复用信号，能检测到工作频段内任何频点处的驻波异常。有用信号前加循环前缀，并引入峰值抵消核，能正确检测到多个反射点驻波。仿真结果表明，该方案驻波测量精度和单回波点位置精度达到预期，多回波点测量能抓准外部主要故障点，在基站VSWR实时测量中具有良好的应用前景。     

薄窗型多阳极气体探测器研究进展

薄窗型气体探测器是最近发展并用于低能量加速器质谱探测技术。该探测器的入射窗采用氮化硅膜，薄而均匀，分辨率高，目前已在低能量粒子探测技术中得到初步应用，显示出广泛的应用前景。本文主要从薄窗型气体探测器基本原理、薄氮化硅膜与Mylar膜的对比、不同质子数Z的低能量粒子脉冲高度对比、薄窗型气体探测器与硅探测器的对比，以及应用等方面进行阐述。     

类铀矿岩材料制备及氡扩散系数测定的实验研究

扩散过程是主导氡在铀矿岩中运移与析出的主要方式。铀矿原岩辐射较大且取样困难,不利于开展有关室内实验。为了解决以上问题,依据相似理论,以某花岗岩为原型,选取石英砂、铀尾砂、水泥、精铁粉和微硅粉等为原材料,制备了3种不同材料配比的圆柱形类铀矿岩试样,并测定了原型和试样的物理力学参数;然后采用密闭腔体法测量了原型和试样在不同包裹方式下的累积氡浓度,推导氡的扩散性能参数的计算公式,通过计算获得了原型和试样的氡扩散长度和扩散系数。实验结果表明:花岗岩原型与所制备的类铀矿岩的颗粒密度、抗压强度、抗拉强度、内聚力和内摩擦角相似比的均值分别为1.09∶1、3.93∶1、4.28∶1、3.47∶1和1.00∶1;花岗岩原型的扩散系数为0.146×10^-6m²·s^-1,类铀矿岩的扩散系数介于0.114×10^-6～0.594×10^-6m²·s^-1之间,两者的相似比介于0.25∶1～1.28∶1之间。研究认为所制备的试样3在一定程度上可用来模拟花岗岩型铀矿岩,以满足室内实验的需求。