A direct quantitative analysis method for monitoring biogenic volatile organic compounds released from leaves of Pelargonium hortorum in situ

A direct quantitative method is presented that is based upon the use of multiple headspace solid phase microextraction (HS-SPME) to monitor biogenic volatile organic compounds (BVOCs) released from a living leaf of Pelargonium hortorum in situ. Seventeen BVOCs were detected by GC-MS after a single SPME extraction using a CAR/DVB/PDMS fibre. An internal standard was employed to determine the absolute amounts of seven terpenoid compounds released from a P. hortorum leaf. The quantitative analysis was performed over two days, with extraction preformed for 20 min every 3 h. The amount of volatiles extracted varied with the time of day, with two maxima recorded at 14:00 (day 1) and 17:00 (day 2), corresponding to 236 and 277 ng of the seven terpenoids recorded, respectively. These results indicate that multiple HS-SPME in combination with an internal standard is a simple, quick, and quantitative technique for analysising BVOC emissions from a live plant sample.     

Synthesis and characterization of second-order nonlinear optical polyurethane with high thermal stability

A second-order nonlinear optical polyurethane was formed with an X-type multi-dimensional charge-transfer (CT) chromophore (DNPIPDHPI) and 3,3^′-dimethoxy-4,4^′-diphenyl diisocyanate. Simultaneous poling and polymerization and in situ second harmonic generation (SHG) measurement technique was carried on to evaluate the thermal stability of the poling induced orientation. The SHG signal of the poled polymer film was not decay below 150 °C and remains 90% of relative d₃₃ value at 200 °C, which is better than the results reported in literature. Comparison of thermal stability indicates that the X-type chromophores possess better property in controlling the decay of the SHG activity than classic chromophores.     

二水草酸锌脱水的热分解动力学研究

提出一种多升温速率-等温法确定机理函数g(α)的新方法;并用迭代的等转化率法求出较为可靠的活化能Ea;在Ea和g(α)的基础上计算出指前因子A.用该法对二水草酸锌（ZnC2O4•2H2O）脱水反应的热分解动力学三因子进行了求算,得出Ea为87.22 kJ•mol－1, A为4.2120×108～7.2328×108 s－1;以及随机成核和随后生长型机理函数Am（Avrami-Erofeer）,其积分形式g(α)=[－ln(1－α)] 1/m和微分形式f(α)=m(1－α)•[－ln(1－α)](1－1/m),调节因子m=1.85～2.00.     

Initial data truncation for multivariate output of discrete-event simulations using the Kalman filter

Data truncation is a commonly accepted method of dealing with initialization bias in discrete-event simulation. An algorithm for determining the appropriate initial-data truncation point for multivariate output is proposed. The technique entails averaging across independent replications and estimating a steady-state output model in a state-space framework. A Bayesian technique called Multiple Model Adaptive Estimation (MMAE) is applied to compute a time varying estimate of the output's steady-state mean vector. This MMAE implementation features the use, in paralle, of a bank of Kalman filters. Each filter is constructed under a different assumption concerning the output's steady-state mean vector. One of the filters assumes that the steady-state mean vector is accurately reflected by an estimate, called the assumed steady-state mean vector, taken from the last half of the simulation data. As the filters process the output through the effective transient, this particular filter becomes more likely (in a Bayesian sense) to be the best filter to represent the data and the MMAE mean estimator is influenced increasingly towards the assumed steady-state mean vector. The estimated truncation point is selected when a norm of the MMAE mean vector estimate is within a small tolerance of the assumed steady-state mean vector. A Monte Carlo analysis using data from simulations of open and closed queueing models is used to evaluate the technique. The evaluation criteria include the ability to construct accurate and reliable confidence regions for the mean response vector based on the truncated sequences.     

伏安型植物组织生物微电极的研究：混合不同植物组织碳糊微电极的研究

由于香蕉组织中含有的氧化酶能够生物催化氧化多巴胺，去甲肾上腺素，Ｌ－多巴等，大大地提高了植物组织电极的灵敏度；又由于茄子组织中所含有的氧化酶在催化氧化儿茶酚的同时，能有效地抑制抗坏血酸在电极上的反应，将上述两种植物组织混合制成电极，使其更适于神经递质的测定，线性范围：２．４×１０＾－６－－９．８×１０＾－４ｍｏｌ／Ｌ；检出下限３．２×１０＾－７ｍｏｌ／Ｌ。     

The Employ of Multiple Voltammetric Pulses for the Study of the Adsorption of Bipyridilium Pesticides in River Sediment

The multiple square‐wave voltammetry (MSWV) allied to gold microelectrode (Au‐ME) was used to establish an electroanalytical procedure for the determination of the paraquat and diquat pesticides in river sediment samples. For both pesticides, two reduction peaks, at around ?0.70 V (peak 1) and around ?1.00 V vs. Ag/AgCl 3.00 mol L^?1 (peak 2), with profile of the totally reversible redox process, were observed. The experimental and voltammetric conditions showed that the best conditions to reduce paraquat and diquat were a pH of 6.0, a frequency of 250 s^?1, a scan increment 2 mV, a square‐wave amplitude of 50 mV and pulse number of 8 pulses of potential in each step of staircase of potential. Under such conditions, the detection limit of 0.044 μg L^?1 (0.044 ppb) and 0.360 μg L^?1 (0.360 ppb ) for peak 1 and peak 2 of paraquat and 0.159 μg L^?1 (0.159 ppb) and 0.533 μg L^?1 (0.533 ppb) for peak 1 and peak 2 of diquat, respectively, were obtained. These results are an order of magnitude of about two less than those obtained and published in the literature. Also, the electroanalytical procedure proposed was applied for the determination of adsorption isotherms of pesticides on river sediments samples collected from Mogi‐Guaçu River in Sao Paulo State, Brazil. The experimental data were fitted using the Langmuir and Freundlich isotherms models; and the results indicated low intensities of adsorption process of the pesticides in the samples employed with distribution coefficients (K_d) lower 5.0, and paraquat showed slightly higher affinity than diquat in the sediments. The increase in organic matter and organic carbon leads to an increase in the K_d values, and consequently an increase in the organic matter constant (K_OM) organic carbon constant (K_OC) values. All results demonstrated that isotherms “L” type in the Giles classification were obtained, indicating that sediments have a medium affinity for the pesticides, and no strong competition from the solvent used (in this case Na₂SO₄) for adsorption sites occurs.     

双二氮杂萘酮类化合物的电喷雾质谱研究

含新型芳香杂环单元的缩聚高分子材料耐老化热稳定性好,具有独特的加工长度和弹性模量,在宇航、电子、机械、军事和复合材料等方面的应用已引起人们的广泛兴趣和关注。含双二氮杂萘酮单元的缩聚高分子材料就是其中一种,这些新型芳香杂环单元大多数熔点都较高,难于汽化,采用电子轰击质谱或快原子轰击质谱测定其相对分子质量时,通常得不到分子离子峰信号,给质谱表征和结构鉴定带来一定的困难。     

Die Berechnung von Einelektronen-Integralen in der SCF-Xα-SW-Methode: I. Die Normierung

A normalization of the wave functions by means of the theoretical exact Multiple-Scattering-(MS)-formalism is discussed within the framework of the SCF-X-SW-method. For the atomic and extramolecular regions the integrals of normalization can be easily determined and the results can be described by the corresponding electronic charges. The calculation of the integral of the interatomic region is problematic. The needful volume integration is only necessary to theGreen's functions of the wave functions and can be solved by means of the residual theory. The further analytical calculation of the surface integrals leads to a complicated formalism which can be numerically evaluated.