二维圆柱坐标系中五角形共形网格算法

 时域有限差分（FDTD）算法求解电磁问题时，如果目标结构不能和传统网格体系共形，往往采用局部共形网格或非正交网格算法。详细讨论了二维圆柱坐标系中五角形共形网格算法，该算法能方便地对倾斜薄层媒质或电导率不均匀的倾斜媒质等复杂结构建模,并以锥形电磁脉冲天线为例，验证了该算法的有效性。     

CsI(Tl)晶体中反冲Cs和I核Quenching?Factor的测量

许多实验对用CsI(Tl)闪烁晶体作为探测器来寻找和探测暗物质的可行性进行了研究.本工作利用8MeV单能中子轰击CsI(Tl)晶体探测器来研究Cs核和I核的QuenchingFactor.在数据处理中,运用脉冲形状甄别(PSD)方法来分辨反冲核信号和本底信号.实验结果表明,在7keV到132keV的能区中,Quench ingFactor随着反冲核能量的减少而增加.在探测暗物质的实验中,这一性质对于CsI(Tl)晶体探测器获得较低的能量阈值是很有利的.     

Long pulse generation technology of solid-state laser adopting a new real time multi-discharge method

In this study, a solid-state laser system adopting a new real time multi-discharge method in which three flashlamps are turned on consecutively was designed and fabricated to examine the pulse width and the pulse shape of the laser beams depending upon the changes in the lamp turn-on time. That is, this study shows a technology that makes it possible to make various pulse shapes by turning on three flashlamps consecutively on a real-time basis with the aid of a program integrated circuit one-chip microprocessor. With this technique, the lamp turn-on delay time can be varied more diversely from 0 to 10 ms and the real-time control is possible with an external keyboard, enabling various pulse shapes. In addition, longer pulses can be more widely used for industrial processing and many medical purposes.     

Fe3O4纳米晶的粒径控制合成、表征及其吸波性能

采用十二烷基磺酸钠和聚乙二醇作为保护剂, 成功地制备出Fe3O4纳米晶. 通过改变实验条件, 可在10~200 nm范围内有效调控Fe3O4纳米晶的粒径. 采用X射线衍射仪、透射电子显微镜和扫描电子显微镜等对样品的微观结构、粒径和形貌进行了分析. 结果表明, 所得尖晶石型Fe3O4纳米晶粒径均匀, 形貌均为球形. 利用振动样品磁场计测量了不同粒径样品的磁性能. 结果显示, 粒径小时, 随着粒径的增加, Fe3O4的饱和磁化强度Ms逐渐增加, 但当粒径增加到80 nm时, Ms达到最大值; 随着粒径的减小, 矫顽力也随之减小. 利用矢量网络分析仪对不同粒径样品的电磁性能和吸波性能进行了研究, 结果表明, 当Fe3O4纳米晶的粒径小于100 nm时, 吸波性能良好, 其中, 粒径为20 nm的样品吸收峰的峰值在8 GHz附近达到了-32 dB.     

电沉积方式对Ni-nanoAl2O3复合镀层组织结构和耐蚀性能的影响

双脉冲;Ni-nanoAl2O3复合镀层;耐蚀性     

Ultra‐Trace Silver Determination in Biological and Water Samples by Electrothermal Atomic Absorption Spectrometry after Electrodeposition on a Graphite Probe

A rapid and simple procedure was developed for selective and sensitive determination of ultra‐trace silver in biological and environmental samples using the electrodeposition on a graphite probe modified with palladium followed by electrothermal atomic absorption spectrometry. Several experimental parameters for the electrodeposition, such as deposition potential, electrolyte concentration, pH of solution and deposition time were optimized. The calibration graph after preconcentration was linear in the range of 10‐250 ngL^?1 with correlation coefficient of 0.9989 under the optimum conditions for procedure. The limits of detection (LOD) and quantification (LOQ) base on (3σ) and (10σ) were 2.8 ngL^?1 and 9.4 ngL^?1 respectively. Related standard deviation (RSD) for eight replicate measurements of 100 ngL^?1 silver was 4.3%. Samples were digested completely in a closed microwave digestion system using only perchloric acid, and interference owing to various cations was also investigated. The proposed procedure was successfully applied to determine silver in blood, urine and some environmental samples with satisfactory analytical results.     

One‐Step Synthesis of Aromatic Terminal Alkynes from Their Corresponding Ketones under Microwave Irradiation

One‐step microwave‐assisted synthesis of phenylacetylenes 2a–j from the corresponding ketones 1a–j in the presence of a new reagent, PCl₅–pyridine, is described. The reaction is carried out under a simple operational and experimental procedure, avoiding the use of the complicated and harsh multistep reaction.     

Microwave Assisted Radical Grafting of Maleic Anhydride onto Polyethylene in Solution

The reaction of maleic anhydride (MAH) grafted onto low density polyethylene (LDPE) in nylene solvents in the presence of benzoyl peroxide (BPO) as an initiator by microwave irradiation has been investigated. The influence of reaction conditions such as initiator content, monomer content and irradiation time have been examined. In the weight composition of xylene/LDPE/MAH/BPO=10/1/1/0.07, the grafting degree reaches 56.5 mmol MAH/100 g PE within only 8 min of microwave irradiation. The grafting reaction time of microwave irradiation shortens over 40 times than in the conventional grafting reaction.     

Macrocyclic ZnII and CuII complexes as guests of the hybrid composites based on the layered MnPS3 phase. Comparison of spectroscopic properties

A family of macrocyclic complexes [M₂LⁿCl₂] have been synthesized and characterized (M: Cu^II or Zn^II; Lⁿ: macrocyclic ligand derived from 2-hydroxy-5-methyl-1,3-benzenedicarbaldehyde and different aliphatic diamines and o-phenylenediamine). The influence of the aromaticity of the ligand and the metal center on the spectroscopic properties of the complexes (absorption and emission) has been studied. Making use of the weak interactions between hydrated potassium ions and the layers of the K_0.4Mn_0.8PS₃ precursor, the obtained macrocyclic complexes have been intercalated in the interlamellar space by a microwave assisted cationic exchange reaction. The optical properties of the obtained hybrid materials are reported. The absorption edge, recorded by solid state reflectance spectroscopy for Cu^II and the Zn^II macrocycle-based composites, is 1.67–1.76 eV, both shifted to lower energy compared with that of the pristine MnPS₃.     

Microwave-assisted synthesis of α-hydroxy aromatic ketones from α-bromo aromatic ketones in water

A reaction ofα-bromo aromatic ketones in water with microwave irradiation gave the correspondingα-hydroxy aromatic ketones in good yields.The use of microwaves was found to significantly improve yields and shorten the reaction time.This reaction afforded a very clean,convenient method for the synthesis ofα-hydroxy aromatic ketones.