碳酸钙共沉淀-火焰原子吸收光谱法测定卤水中的痕量钴

以碳酸钙共沉淀,用火焰原子吸收光谱法测定卤水中的痕量钴,对试剂的加入量富集时间,酸度等因素进行了实验,选择了最佳的共沉淀条件.方法已用于卤水分析,加标回收率:钴94.6%-98.7%.检出限:钴为1.89μg·L-1.本法测定手续简便、快速、结果满意.     

ICP-AES测定二氯化钯中的杂质元素

PdCl2试样用氨水溶解,加Y作载体共沉淀分离富集杂质元素,富集物转化成盐酸溶液,ICP-AES测定Pb、Sb、Bi、As、Sn、Fe、Zr、Cr、Be、Ti等杂质元素。测定范围为0.0002%-0.01%,加标回收率为84%-114%。相对标准偏差为2.2%-7.4%。方法准确、简便。     

ICP-AES测定葡萄糖酸钙中Pb、As、Cd等9个杂质元素

本文应用ICP-AES直接测定了葡萄糖酸钙中的Pb、As、Cd等9个杂质元素,对样品的消解方法、基体和酸介质的影响等进行了讨论.用基体匹配法消除钙基体的干扰,9个杂质元素测定的测定范围为:Pb 0.0008%-0.08%,Cu、Mg 0.0001%-0.01%,其余元素0.0003%-0.03%.加标回收率为95.8%-100.0%,相对标准偏差为0.16%-3.61%.     

用sension^TM156便携式测量仪测定水中总溶解性固体

用sensiontTM156便携式多参数测量仪测量水中总溶解性固体,仪器校正后即测即得结果.自动储存记录、自动显示,仪器从校正到测量结束整个过程用时不到10min,测定下限为5mg/L,相对标准偏差在1.94%-2.55%范围内,样品的加标回收率97%-102%.     

石墨炉原子吸收光谱法测定尿中镍

用PEAA600石墨炉原子吸收光谱仪测定尿中镍,并探讨相关实验条件.取尿样0.5mlL用0.2%硝酸处理后,用具横向加热石墨炉原子化器(THGA)系统和纵向Zeeman效应背景校正的PEAA600石墨炉原子吸收光谱仪,全自动进样和添加基本改进剂进行测定.检出限为1.5μg/L,相对标准差(RSD)在0.952%-6.329%之间,回收率在87.6%-106.9%之间.结果表明,本法简单实用,稳定性好,有可靠的精密度和准确度,是-种理想的尿中镍测定方法.     

ICP-AES测定钾石盐中钾、钠、钙和镁的含量

在选定的最佳条件下,样品直接溶解后采用ICP-AES测定钾石盐中钾、钠、钙、镁的含量,其最终检测结果与化学法测定结果一致.该方法简便、快速、线性范围宽、测量稳定、可多元素同时测定.回收率为98.3%-100.2%.     

食用植物油中溶剂残留的测定方法

通过质谱法确定了食用植物油溶剂残留中除正己烷以外的3种主要六碳烷烃,并以正己烷为标准物质,采用顶空进样-气相色谱法测定食用植物油中的溶剂残留量.研究了食用植物油中溶剂残留量的定性和定量测定方法;比较了3种六碳烷烃与本检测方法的相对标准偏差进行了比较.结果表明,方法加标回收率为97.98%-98.88%,相对标准偏差在2.5%-3.4%之间,最低检出限为0.001mg/L,方法简单、准确.     

PAN共沉淀分离富集微量注射进样FAAS测定人发中的痕量镉

本文报道了采用PAN共沉淀分离富集微量进样技术-FAAS法对人发中的痕量镉的测定。镉的测定范围在0～25μg/L,回收率在96～107%之间,变异系数为7.2%,得到了满意的结果。     

ICP-AES测定金合金中钆和铍含量

通过ICP-AES测定金合金中Gd和Be量各种相关因素的试验研究,建立了一个准确可靠的测定方法以替代原国标方法,适用于AuAgCuMnGd、AuAgCuGd、AuNiGd、AuBe合金中钆、铍量的测定,测定含量范围为:0.2%-2%.方法加标回收率:Gd为95.58%-99.98%,Be为96.11%-103.33%.方法测定精密度结果:Gd为1.02%.Be为4.05%.     

滤纸固体基质表面荧光法测定痕量蒽、芘

建立了以滤纸为基质的蒽和芘的固体表面荧光分析法(SSF).考察了影响蒽、芘SSF强度的各种因素,包括滤纸的种类、待测样的烘干时间和烘干温度等.实验表明,蒽的线性范围为7×10-7-5×10-5mol/L,检出限为0.36ng/斑,加标回收率在89.5%-113.4%之间,相对标准偏差为4.89%;芘的线性范围为4×10-6-1×10-3mol/L,检出限为0.10ng/斑,加标回收率在83.5%-120.4%之间,相对标准偏差为4.96%.     

Self-organization of five species in a cyclic competition game

Cyclic competition game models, particularly the “rock–paper–scissors” model, play important roles in exploring the problem of multi-species coexistence in spatially ecological systems. We propose an extended “rock–paper–scissors” game to model cyclic interactions among five species, and find that two of the five can coexistent when biodiversity disappears, which is different from the “rock–paper–scissors” game. As the number of fingers is five, we named the new model the “fingers” game, where the thumb, forefinger, middle finger, ring finger, and little finger cyclically dominate their subsequent species and are dominated by their former species. We investigate the “fingers” model in two ways: direct simulations and nonlinear partial differential equations. An important finding is that the number of species in a cyclic competition game has an influence on the emergence of biodiversity. To be specific, the “rock–paper–scissors” model is in favor of maintaining biodiversity in comparison with the “fingers” model when the variables (population size, reproduction rate, selection rate, and migration rate) are the same. It is also shown that the mobility and reproduction rate can promote or jeopardize biodiversity.     

Contrastive analysis on tone between Putonghua and Taiwan Mandarin

The differences of the pitch and duration of Chinese syllables between Putonghua （PTH） and Taiwan Mandarin （TM） were studied. The speech materials to be used are not only isolated syllables, but also sentences. The results reveal that： For the isolated syllables, T1 and T2 in TM are influenced by Minnan dialect, therefore their pitch are lower than those in PTH. T3 is fall-rise in PTH, while it is fall in TM. Moreover, the syllable duration sequence for different tone is T3〉T2〉T1〉T4 in PTH, while it is T1〉T2〉T3〉T4 in TM. For the syllables in sentences, T2 is mid-rise in PTH, while it is mid-level in TM. And the T3 is longer than T4 but shorter than T1 or T2 in PTH, while it is the shortest in TM. Furthermore the effects of prosodic phrase boundary on duration for different tones are almost the same in PTH, but the lengthening part of T1 or T2 is longer than that of T3 or T4 in TM.     

Experimental study on downstep in Chinese intonation

Downstep in pitch contour of Chinese Putonghua is examined using subtly designed sentences by controlling tone combinations. The results show both automatic and nonautomatic downstep phenomena exist in Chinese. In non-automatic downstep, low tones compress downwards the pitch range of the following syllables. and the main influence of downstep is on topline. Low tone not only lower the topline behind it, but also raise the high tones before it, the effects are compatible with each other. In automatic downstep, the topline of pitch contour in intonational phrase is presented as a linear downtrend, but it differs among speakers due to the effect of personal stress practice. In comparison with downstep phenomenon in other tone or non-tone languages, the downstep ratio in Chinese is not constant, and the domain of downstep is not limited within the adjacent tones.     

Abelian-Higgs phase of SU(2) QCD and glueball energy

It is shown that SU(2) QCD admits an dual Abelian-Higgs phase, with a Higgs vacuum of a type-Ⅱ superconductor. This is done by using a connection decomposition for the gluon field and the random-direction approximation. Using a bag picture with soft wall, we presented a calculational procedure for the glueball energy based on the recent proof for wall-vortices [Nucl. Phys. B 741(2006)1].     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Signal generation in an isotropic medium in scanning electron acoustic microscope

Based on the research in Ref. [5][Materials Science and Engineering, 1989; A122： 57 63], an improved model of heat source is set up, the different modes of Lamb wave in an isotropic sample generated by a chopped electron beam at frequency f are obtained with integral transform and normal function expansion method, and the output signal of PZT coupled at the back surface of the sample is found out. The generation mechanism of SEAM （Scanning Electron Acoustic Microscopy） signal is discussed. It shows that the SEAM is a near field imaging technique with high spatial resolution and its best lateral spatial resolution is about 2√2α （α is the radius of the focused electron beam）. Some of experimental results of SEAM images are presented in the paper and it shows that the spatial resolution of SEAM is better than 0.5 μm and smaller than the thermal diffusion length of the sample. Therefore the character of near field imaging in SEAM is also proved experimentally.     

High efficiency filtering using two-dimensional photonic crystal coupled cavity structures

Transmission spectra of coupled cavity structures (CCSs) in two-dimensional (2D) photonic crystals (PCs) are investigated using a coupled mode theory, and an optical filter based on CCS is proposed. The performance of the filter is investigated using finite-difference time-domain (FDTD) method, and the results show that within a very short coupling distance of about 3λ, where λ is the wavelength of signal in vacuum, the incident signals with different frequencies are separated into different channels with a contrast ratio of 20 dB. The advantages of this kind of filter are small size and easily tunable operation frequencies.