高效液相色谱测定海虾中呋喃唑酮残留量

样品用二氯甲烷提取,正己烷纯化、外标法定量,高效液相色谱(HPLC)法检测海虾中呋喃唑酮残留量.本方法校准曲线线性范围为0.01-1.00μg/mL,r=0.9991.检测下限为1.0μg/kg,回收率92.0%-100.5%,相对标准偏差(RSD)为2.9%-4.6%.测定方法准确,灵敏,达到了水产品检测的要求.     

快速溶剂萃取气相色谱法测定蔬菜中六六六和滴滴涕的残留量

建立了蔬菜中六六六和滴滴涕残留量快速溶剂萃取气相色谱的分析方法。该法的α-六六六、β-六六六、γ-六六六、δ-六六六、PP’-滴滴伊、OP’-滴滴涕、PP’-滴滴滴、PP’-滴滴涕检出限均≤0.05μg/L。加标回收率为88.6%—101.1%,相对标准偏差(RSD)小于8%。该法步骤简单快速,适用于蔬菜中六六六和滴滴涕农药的快速检测。     

3种铝分析方法在定量测定海参产品的比较

建立了海参产品中铝残留量的3种定量分析方法,即紫外分光光度法、石墨炉原子吸收光谱法和电感耦合等离子体-质谱法.在各自优化的条件下将3种方法用于铝的检测,比较结果表明:ICP-MS除具有线性范围宽(1-200μg/L),灵敏度高的特点外,还具有简单、快速、体系稳定性好等优点.     

ICP-AES同时测定钼矿石中多种元素

采用碱熔酸化和ICP-AES同时测定钼矿石样品中Mo、SiO2、P2O5、CaO、Fe2O3、S、Cu、Pb、Zn、Sn、As等多种元素,检出限分别为0.1μg/g、0.005%、0.03%、0.003%、0.001%、5μg/g、0.5μg/g、0.7μg/g、0.3μg/g、1.5μg/g、1μg/g;RSD为1.2%-3.8%.该法准确,快速,简便,结果令人满意.     

双道原子荧光光谱法同时测定农产品中的砷和硒

研究了AFS-930型双道原子荧光光度计同时测定农产品中砷和硒的方法.该法快速,简便,准确,砷回收率为91.9%-99.6%,硒回收率为93.5%-103.8%,相对标准偏差(RSD)砷小于2%,硒小于1%,检出限分别为0.035μg/L和0.038μg/L.     

方波伏安法测定罗布麻叶中锌含量

使用BAS 100A电化学分析仪,应用方波伏安法测定了罗布麻叶中锌的含量.在NH3-NH4Cl缓冲液(pH=10)中,-860mV峰电位下产生一个灵敏峰,检测罗布麻叶中的锌,以校准曲线法定量.建立了回归方程y(μA)=52.52 1610.79x(μg/mL),相关系数r=0.9582.回收率为97.04%,RSD为0.72%.方法简便快速、灵敏度高.     

标准加入法在能力验证考核酱油铅含量中的应用

采用标准加入法-硝酸钯基体改进剂消除酱油中食盐的机体干扰,建立了标准加入法-硝酸钯基体改进剂GFAAS测定酱油中痕量铅的方法,该方法的检出限为4.2μg/L,精密度为1.52%—4.96%,在5、20μg/L添加水平回收率为91.6%—108.2%,90.5%—101.7%,方法简单、快速、检出限符合标准分析要求。     

高效液相色谱法同时测定饮料中苯甲酸和山梨酸

探讨了同时测定饮品中苯甲酸、山梨酸的分析方法.采用高效液相色谱(HPLC)法分离和检测样品中苯甲酸、山梨酸.将样品除去CO2后,用氨水调节pH=7,滤膜过滤.外标法定量,检测饮料中苯甲酸、山梨酸含量.苯甲酸、山梨酸校准曲线线性范围为0.5-20.0μg/mL,r分别为0.9985和0.9990.检出限分别为0.44μg/mL,和0.32μg/mL,回收率76.3%-105.4%,相对标准偏差(RSD)1.27%-7.67%.使用高效液相色谱法同时测定饮料中苯甲酸山梨酸的方法准确,灵敏,达到了实验方法的要求.     

电感耦合等离子体-质谱法测定岩石和矿物中的钨和钼

采用高氯酸-氢氟酸-硝酸处理样品,电感耦合等离子体质谱法测定岩石矿物中的钨钼,避免了极谱法中汞对人体的伤害,测定的相对标准偏差（RSD,n=8）小于2.0％.方法的检出限Mo为0.065μg/g;W为0.092μg/g.用不同类型国家一级标准物质验证,结果与标准值吻合较好.该方法适用于岩石矿物中钨和钼的检测,重现性好,灵敏度较高,能满足简单、快速、批量分析要求.     

微波消解-电感耦合等离子体-质谱测定蔬菜中的铅和镉

用微波消解-电感耦合等离子体-质谱测定蔬菜中的Pb和Cd,方法简便、快速.Pb和Cd检出限分别为0.14μg/L和0.13μg/L,相对标准偏差(RSD,n=5)＜4.69%,标准加入法回收率Pb为96.0%-104.0%,Cd为95.0%-110.0%.方法经国家一级植物标准物质验证,结果与推荐值相符.     

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].     

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.     

Real-time restoration of rotational blurred image using gradient-loading

The key to the restoration of rotational motion blurred image is how to restore the image under a low cost and to correct the irreversibility of the degradation function matrix.Based on the special qualities of degradation function matrix and precise deduction in space-domain, we present a new approach using gradient-loading for restoration of rotational blurred image.By easily adding a gradient operator, the irreversibility of the original matrix is corrected and can be applied for inverse filtering then.Gradientloading is the optimized approach which combines the advantages of both the approaches using constrained least square filtering and traditional diagonal-loading.Compared with the approach using least square filtering, its peak signal-to-noise ratio (PSNR) is improved from 3.18 to 6.46dB, while the computing time is reduced to 1/2-1/3.Experimental results demonstrate the effectiveness, noise-resistibility, robustness, and low complexity of this approach, which make it more suitable for real-time environment.     

All-Optical Logic Device Using Bent Nonlinear Tapered Y-Junction Waveguide Structure

We propose an all-optical logic device made of a bent tapered Y-junction waveguide with a Kerr-type nonlinear interface. It could provide an AND gate, OR gate, and exclusive-OR (XOR) gate. We could obtain different transmission results by adjusting the bending angle. The numerical simulation results show that the device functions as AND, OR, and XOR gates.     

Real-time, continuous-wave terahertz imaging by a pyroelectric camera

Real-time, continuous-wave terahertz (THz) imaging is demonstrated. A 1.89-THz optically-pumped farinfrared laser is used as the illumination source, and a 124 × 124 element room-temperature pyroelectric camera is adopted as the detector. With this setup, THz images through various wrapping materials are shown. The results show that this imaging system has the potential applications in real-time mail and security inspection.