氯酚红共振瑞利散射法测定残留氯霉素

建立了测定残留氯霉素的共振瑞利散射法.在pH 9.25的Tris-HCl缓冲溶液中,氯霉素与氯酚红相互作用后,共振瑞利散射显著增强,在407nm处呈现最高散射强度.氯霉素的质量浓度在0.030-0.260μg/mL范围内与ΔⅠRRS成正比,检出限(3Sb/S)为0.0020μg/mL.该法简便、快速、灵敏,可用于虾及奶粉中氯霉素残留测定.     

FAAS法测定硫酸中的铜、铁和锌

采用火焰原子吸收光谱法测定硫酸中铜、铁和锌,确定了最佳仪器工作条件和样品处理方法.在选择好的实验条件下,测定铜的特征浓度为0.005μg/mL/1%;铁的特征浓度为0.014μg/mL/1%吸收;锌的特征浓度为0.002μg/mL/1%吸收.回收率分别为铜97.7%-98.2%,铁98.2%-99.4%,锌96.8%-98.7%.     

RP-HPLC法测定氯霉素固体脂质纳米粒中氯霉素含量

建立RP-HPLC法测定氯霉素固体脂质纳米粒含量.采用Hypersil ODS C18(4.6mm× 200mm,5μm)色谱柱,流动相为甲醇-0.34%磷酸二氢钾水溶液(45∶55,V/V),检测波长273nm,流速1.0mL/min,柱温30℃.结果表明在2-20μg/mL范围内,氯霉素线性良好(n=6,r=0.9...     

流动注射-蒸气发生原子吸收光谱法测定生物样品中的汞

在选择了生物样品最佳消化方法、汞蒸气生成及检测最佳条件等的基础上 ,将流动注射 (FI)与蒸汽发生原子吸收光谱法 (VG- AAS)有机地结合起来 ,建立了生物样品中汞含量的测定方法。该法简便、快速、灵敏度高 ,测定的相对标准偏差 (n=6 )为 2 .8%— 3.3% ,试样加标回收率为 97.2 %— 10 1.4 % ,检出限为 0 .0 5μg· L- 1 ,特征浓度为 0 .5 5μg· L- 1 / 1% ,用于生物样品中汞的测定 ,结果令人满意     

FAAS测定电解镉中的Zn、Cu和Fe

采用火焰原子吸收光谱法测定电解镉中铜、铁和锌的方法,确定了最佳仪器工作条件和样品处理方法.在选择好的实验条件下.测定铜的特征浓度为0.006#g/mL/1%吸收;铁的特征浓度为0.015μg/mL/1%吸收;锌的特征浓度为0.0031μg/mL/1%吸收.回收率分别为铜97.5%-98.0%,铁99.1%-100.2%,锌97.4%-99.1%.     

光泽精化学发光体系的研究与应用

对光泽精化学发光体系的动力学性质、荧光光谱、化学发光光谱及化学发光机理进行研究和探讨。详细研究了光泽精 - H2 O2 - Co( )流动注射化学发光体系的最佳分析条件。结果表明 ,当光泽精 (L c)为 2 .5×10 - 5mol/L、H2 O2 为 0 .5 mol/L、Na OH为 0 .4 mol/L、CTMAB为 2 .0× 10 - 5mol/L时 ,测定 Co( )的校准曲线线性范围为 0 .0 5— 2 0 0μg/m L ,检出限为 0 .0 1μg/m L。对 10μg/m L Co( )连续测定 7次 ,相对标准偏差为 1.7%。     

二甲苯胺蓝褪色光度法测定水中痕量铬

研究了在酸性介质中铬(Ⅵ)催化溴酸钾氧化二甲苯胺蓝褪色的最佳条件.本法λmax=515nm,表观摩尔吸光系数为2.5×104L·mol-1·cm-1,线性范围为0-26μg/25mL.用于水样中痕量铬的测定,结果令人满意.     

微波消解-氢化物发生原子荧光光谱法测定土壤中砷和硒

采用王水(1 1)作消解剂,以微波消解的方法处理土壤样品,氢化物发生-原子荧光光谱法测定土壤中砷、硒,设定了最佳的样品处理条件和仪器测定条件.利用加标回收试验,对分析方法进行了验证.砷、硒的检出限分别为0.94μg/L和0.15μg/L,测定土壤中砷、硒的回收率分别为90%-105%、89%-104%,RSD分别为2.2%-4.0%、1.9%-3.1%.     

用石墨炉原子吸收光谱法测定血清镉

建立一种血清镉的石墨炉原子吸收光谱测定法.将血清和0.44mol/L的优级纯HNO3按1:9充分稀释后,15000r/min高速离心10min,取上清20μL,直接在PE-AA800型原子吸收分光光度计上测定,研究发现最佳灰化温度为700℃,最佳原子化温度为1700℃,最佳净化温度为2000℃和基底改进剂为50μg磷酸二氢铵 3μg硝酸镁;平均回收率可达到102.0%;相对标准偏差(RSD)小于8.0%;特征浓度为1.70992pg/0.0044A,检出限为0.9327pg.本法为一种可信度较高,操作性较强的血镉的实用测定方法.     

茜素蓝S与氯霉素的显色反应及应用

研究了茜素蓝S与氯霉素的显色反应,建立了测定氯霉素的可见分光光度法。在酸性Britton-Robinson缓冲介质中,茜素蓝S与氯霉素反应生成的络合物导致吸光强度(ΔA)显著增大。最大正吸收波长位于638nm,表观摩尔吸光系数(ε)为1.32×104L·mol-1·cm-1;最大负吸收波长为566nm,表观摩尔吸光系数(ε)为8.00×103L·mol-1·cm-1;氯霉素的浓度在0—2.0×10-5mol.L-1范围内遵从比耳定律。探讨了适宜的反应条件、主要分析化学性质及方法的精密度和可靠性。方法用于市售氯霉素药物中氯霉素的测定,结果满意。     

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.