Synthesis of hexagonal monocrystal AlN microtubes and nanowires at low temperature

This paper reports that pure hexagonal aluminium nitride microtubes and nanowires growing along the [0001] direction have been successfully synthesized by directly reacting AlClh-AlN, microtubes, nanowires,h-AlN, microtubes, nanowiresProject supported by the National Natural Science Foundation of China (Grant No 10474078) and the Science Foundation of the Education Office of Shanxi Province, China.2006-11-23This paper reports that pure hexagonal aluminium nitride microtubes and nanowires growing along the [0001] direction have been successfully synthesized by directly reacting AlCl3 with NaN3 at low temperature （450℃） under condition of non-solvent system. The grey-white powder of reacting product was characterized by high-resolution transmission electron microscope （HRTEM）, which shows that the powder is long straight-wire morphology with outer diameter from 40nm to 300 nm and length up to several micrometres. The results of both electron diffraction （ED） and x-ray diffraction （XRD） indicate that the AlN microtubes have a pure hexagonal monocrystal tubular structure with the combination of the curled AlN nanobelts. Room-temperature photoluminescence spectrum of the synthesized sample showed an emission peak, which is closely related to the small size of the microtubes.     

内蒙古草原植被最大光能利用率取值优化研究

针对目前CASA (carnegie-ames-stanford approach)模型等植被生产力模型植被最大光能利用率的取值未对草原进行区分的问题,以内蒙古草甸草原、典型草原和荒漠草原为研究对象,结合野外实测NPP(net primary productivity)数据和CASA模型的建模思路优化了三大草原类型植被最大光能利用率,并以此为基础模拟分析了其植被光能利用率和NPP时空格局。结果表明,基于99个地面采样点所建立的一元二次方程模拟的草甸草原、典型草原和荒漠草原最大光能利用率分别为0.654,0.553和0.511 gC·MJ-1,平均为0.573 gC·MJ-1。与未对草原类型进行区分而统一取值为0.541 gC·MJ-1的结果相比,实测NPP与模拟NPP之间的决定系数和和均方根误差分别提高了0.024和2.62 gC·(m2·month-1)-1。受水热组合和草原类型的空间格局的影响,内蒙古草原植被光能利用率和NPP总体上由东北向西南逐渐下降趋势,呈明显的单峰季节变化特征。但光能利用率和NPP的最大值出现的月份有所不同,分别出现在8月份和7月份,这可能与植被吸收的光合有效辐射和光能利用率的最高值出现的月份不同有关。光能利用率和NPP平均值按草甸草原>典型草原>荒漠草原的顺序依次降低。     

Properties of Dihadron Correlations for p＋p Collisions at √8NN = 200 GeV

The dihadron azimuthal angular correlations for p＋p collisions at √8NN = 200 GeV are simulated by a multiphase transport model. The dispersions of near-side and away-side peaks, indicated by the width of Gaussian fit functions and the rms width, decrease with the transverse momentum of associated particles. This trend is consistent with the experimental results. Conditional-yields are also calculated to obtain distributions of the associated particle transverse momentum for both away-side and near-side. Furthermore, the hadronic rescattering effects make the conditional-yield distributions softer.     

An Optical Labeling Scheme with Novel DPSK/PPM Orthogonal Modulation

A novel differential-phase-shift-keying （DPSK）/pulse-position-modulation （PPM） orthogonal modulation is pro- posed for optical labeling applications, with PPM data as the high-speed payload and DPSK signal as the optical label. The systematic setup for the proposed scheme and research on bit-error rate is presented. The results show that at the bit-error rate of 10-~, the power penalties for 70kin fiber transmission are in the range of 1-3 dB to DPSK label and 5-6 dB to PPM payload in our simulation system. This is under the condition that the large extinction ratio of 18-19 dB is used for the intensity modulators of the PPM payload, with a well received DPSK label. Thus the feasibility of the proposed scheme for all optical transmission networks is clearly verified.     

金刚石/硅(001)异质界面的分子动力学模拟研究

采用分子动力学方法模拟研究了未重构的金刚石/硅(001)面相接触时界面层原子的弛豫过程及所形成的异质界面的结构特征.硅碳二元系统中原子间的相互作用采用Tersoff多体经验势描述.弛豫前沿[110]与[110]方向界面碳硅原子数之比均为3∶2.界面碳硅原子总数之比为9∶4.弛豫后金刚石与硅界面处晶格匹配方式改变为[110]方向基本上以3∶2关系对准,而[110]方向大致以1∶1关系对准.相应地,界面碳硅原子总数之比接近3∶2.界面下方部分第二层硅原子在弛豫过程中向上迁移至界面是引起这种变化的原因,同时该层其他原子及其底下一到两个原子层厚度的区域在[001]方向上出现一定程度的无序化转变倾向.金刚石/硅异质界面处的硅碳原子发生强烈键合,形成平均键长为0.189nm的硅碳键.研究证实,晶格匹配主要呈现界面及其附近硅原子迎合界面碳原子排列的特点. 关键词： 金刚石 硅 异质界面 分子动力学     

Broadband Convergence of 40 GHz-ROF and 10-Gb/s WDM-PON Systems in the Duplex Access Network

A broadly converged 40G-ROF and 10-Gb/s WDM-PON multi-service access system is proposed and exper- imentally demonstrated. This scheme consists of an integrated system of 40G-ROF and 10-Gb/s WDM-PON simultaneously transmitting independent 2.5-Gb/s wireless and 10-Gb/s wire signal. At the base station, it employs a remodulation scheme, which is achieved by remodulating the upstream OOK signal on the DPSK downstream signal, to reduce the cost of the base station. The transmission experiment is carried out over a 25-km-long single mode fiber （SMF-28）. The results show that the sensitivities of downstream PON and ROF signal are -14.5 dBm and -21.5 dBm, respectively, and the sensitivity of upstream signal is -25.3 dBm.     

紫外光谱估测贵州天麻中的天麻素

采用高效液相色谱法和紫外光谱法测定名贵中药材贵州天麻样品中天麻素的含量,选择在最大吸收波长223nm处,分析天麻素含量与紫外光谱的吸光度数值之间的相关性.采用先聚类后回归的分析法进一步估测天麻中天麻素的含量.结果表明:在223nm处,天麻素含量与紫外光谱的吸光度数值呈显著相关,其相关系数均达到0.98以上.对回归模型进行检验,预测值与实测值吻合.这表明紫外光谱法可为系统评价贵州天麻等级提供理论依据和相关技术手段.     

Synchronization and Pattern Dynamics of Coupled Chaotic Maps on Complex Networks

The synchronization and pattern dynamics of coupled logistic maps on a certain type of complex network, constructed by adding random shortcuts to a regular ring, is investigated. For parameters where an isolated map is fully chaotic, the defect turbulence, which is dominant in the regular network, can be tamed into ordered periodic patterns or synchronized chaotic states when random shortcuts are added, and the patterns formed on the complex network can be grouped into two or three branches depending on the coupling strength.     

Hybrid Optoelectronic Bistability in Frequency-Domain and Its Potential Application in FBG Sensors

We propose a novel optical bistable device （OBD） in frequency-domain with which we can perform optical bistable operations in a number of fibre Bragg gratings （FBGs） which are included in the same OBD. Such an OBD may bring more opportunities in applications and, as an example, we show the possibility of using it in an FBG sensor demodulating system. By use of a tunable light source, consisting of a broad band source and a scanning fibre F-P （FFP）, we demonstrate the above-mentioned operations experimentally.     

基于双膦配体、氮配体的两个铜(Ⅰ)配合物的合成、光谱学性质和太赫兹时域光谱

在甲醇和二氯甲烷的混合溶剂中合成了2个新的铜??配合物:[Cu(dppp)(Bphen)]Cl·1.8CH3OH(1)和[Cu2(CN)2(dppp)(dmp)2]·2.5CH3OH(2)(dppp=1,3-双(二苯基膦基)丙烷,Bphen=4,7-二苯基-1,10-菲咯啉,dmp=2,9-二甲基-1,10-菲咯啉),...