DIFFERENTIAL PULSE VOLTAMMETRIC DETERMINATION OF 3,3''''5,5''''-TETRAMETHYLBENZIDINE AND ITS ANALOGUES WITH A GLASSY CARBON ELECTRODE

The differential pulse voltammetric (DPV) method-with a glassy carbon electrode was used for the determination of 3,3' 5,5'-tetramethy lbenzidine (TMB), o-tolidine and benzidine in the acidic media. The pulse amplitude, interval time and scan rate of DPV are optimized to be 50 mV, 0. 5 s and 10 mV/s, respectively. The peak current, is proportional to the concentration of TMB and its analogues, the linear range is from 10~(-6)mol/l to 10~(-4)mol/l. The electrochemical behaviour of the compounds is discussed. The chemical poisons can be determined directly, or indirectly by the extraction in the waste water of chemical industry and laboratory.     

Trace determination of zirconium using anodic adsorptive voltammetry at a carbon paste electrode modified with multi-walled carbon nanotubes

A carbon paste electrode modified with multi-walled carbon nanotubes （MWCNT） was prepared and the determination of ultra trace amount of zirconium based on the anodic adsorptive voltammetry of the zirconium-calcium-alizarin red S mix-polynuclear complex is described in this paper for the first time. The results showed that the sensitivity and the selectivity of the method are excellent. The second derivative linear scan voltammograms of the complex were recorded by polarographic analyzer from 200 to 1200 mV （vs. SCE） and it was found that the complex can be adsorbed on the surface of the electrode, yielding a peak at about 840 mV, corresponding to the oxidation of ARS in the complex. The peak current increases linearly with Zr （IV） concentration in the range of 6.0×10^-12--6.0×10^-11 mol. L^-1 （accumulation time 120 s）, 6.0×10^-11--2.0×10^-9 mol. L-1 （accumulation time 90 s） and 2.0×10^-9--1.0×10^-7 mol. L^-1 （accumulation time 60 s） and the detection limit （S/N = 3） is 2.0×10^-12 mol. L^-1 （accumulation time 180 s）. The procedure has been successfully applied to the determination of zirconium in the ore samples.     

The minimization of non-equilibrium plasma source at high pressure

The density of plasma produced by atmospheric non-equilibrium plasma source is the function of energy dissipation rate in ionization electric field and gas particles momentum. The experiment shows that the plasma density highly rises with the increasing of energy dissipation rate and gas particles momentum. When the energy dissipation rate of activation field is 2.18 Wh/m^3 and the average gas particles momentum is 109×10^-22 g· m/s, the air throughput of plasma source whose volume is only 2.5 cm^3 can be up to 12 m^3/h and the density of plasma can be up to 10^10 cm^-3. The research can develop a method of producing minitype plasma source which is low energy consumption but high ion concentration used for chemical industry, environmental engineering and military.     

Research of Inclusion Complexation of 4,4＇-Thiodiphenol Effected by β-Cyclodextrin in Aqueous Solutions and the Effect on Photodegradation

The inclusion behavior of 4, 4＇ -Thiodiphenol （TDP）, a typical bisphenol and endocrine disruptor, reacts with β-cyclodextrin （β-CD） in aqueous solutions has been investigated by means of UV absorption spectrum and quantum-chemical calculation with Gaussian 98 software. The results show that the inclusion behavior of TDP is quite different in acidic solutions （pH 5.9） from that in alkaline solutions （pH 10.0）. This behavior difference is attributed to the different formula structures in aqueous solutions at acidic and alkaline pH values that are demonstrated by quantum- chemical modeling and calculation. TDP forms a 1 ： 1 fl-CD inclusion complex in aqueous solutions. The equiiibrium constant K was calculated to be 553.49 L/mol at pH 5.9 and 1 318.20 L/mol at pH 10.0 respectively for the inclusion complex reaction by using the modified Benesi-Heldbrand equation. After inclusion TDP＇s structure is changed especially at the inclusion part with the bond order becoming larger, which results in inhibitive photodegradation during direct photooxidation and H2O2 assisted photooxidation.     

Electrical bistable characteristics of poly（phenylene sulfide） thin film deposited by thermal evaporation

Poly（phenylene sulfide） （PPS） is a well-known organic insulator. However, the PPS thin film, deposited by thermal evaporation in vacuum, showed electrical bistable characteristics. The structure of the PPS thin-film device was glass/ITOIPPS （300 nm）/Au. The thin film can be converted to a high conductance state by applying a pulse of 80 V （5 s）, and brought back to a low conductance state by applying a pulse of 100 V （5 s）. This kind of thin film is potential for active layer of a memory device. The critical voltage of the device is about 40 V, while the read-out voltage is 5 V. We tentatively ascribe the bistable phenomenon to the charge transfer from S to C atoms in the PPS molecule chains.     

THE TRANSFER BEHAVIOUR OF SOME CATIONS AT WATER／NITROBENZENE INTERFACE BY SEMIDIFFERENTIAL CYCLIC VOLTAMMETRY

The transfer of Sr~(2+) and Ba~(2+) ion, facilitated by 18-Crown-6 present in the aqueous phase, and of succinylcholine ion at w/nb interface were investigated by semi-differential cyclic voltammetry. A good polarographic curve of succinylcholine ion dissolved in water was obtained in the system of 0.01 mol/l LiCl (w)——0.01 mol/l TBATPB (nb). The peak current is directly proportional to the concentration of SC~(2+) ion. It can be used for the determination of SC and the detection limit is 1.05×10~(-5) mol/l.The apparent D~w and D~(nb) have been estimated. The transfer of Sr~(2+) and of Ba~(2+) at the interface are facilitated by 18-Crown-6 present in the aqueous phase and the peak current is directly proportional to the concentration of 18-Crown-6 in water. This method can be used for the determination of the complexing agent and for the stability constant of the complex formed in the aqueous phase.All the experimental results are in keeping with the theoretical.     

Permeation of vanadium（Ⅲ, Ⅳ, Ⅴ）-dipicolinate complexes across MDCK cell monolayer and comparison with Caco-2 cells

The permeation and eytotoxicity of three insulin-mimetic vanadium（Ⅲ, Ⅳ, Ⅴ）-dipicolinate complexes were studied using the MDCK cell monolayer in comparison with the Caeo-2 cells. On MDCK cell monolayer, the apparent permeation coefficients （Papp） were estimated to be （7.5±1.0）×10^-6, （1.0±0.2）×10^-6, （1.7±0.4）× 10^-6cm/s for V（Ⅴ）, V（Ⅵ）, and V（Ⅲ）-dipie complexes, respectively. The permeability of V（Ⅴ）-dipie complexes is much better than the others, which is in agreement with its better hypoglycemie effect in animal tests. On Caeo-2 cell monolayer, Papp were found to be in the range of 1-3×10^-6 ends and not to be affected by excessive amounts of dipieolinate ligand. By contrast, the permeability in the AP→BL direction across the MDCK monolayer increased greatly in the presence of free ligands, suggesting existence of active transport mechanism of vanadium complex anions on the MDCK cells. The eytotoxieity of the three complexes was found similar and the IC50 were measured in the range of 0.6-0.9 mmol/L for MDCK cells and 1.6--2 mmol/L for Caco-2 cells. The cytotoxicity of three vanadium complexes was conceivably in consistence with their permeability, suggesting that the toxicity, permeation and cellular metabolism of vanadium complexes are closely related.     

Radiation properties of high-order harmonic generation for the measurements of femto- and attosecond X-ray pulses

Radiation properties of high-order harmonic generation （HHG） are calculated for atoms in a strong laser field. The laser-duration dependence and the carrier-envelope-phase （CEP） dependence of HHG radiation properties are presented. The CEP dependence of the pure single distribution pulse of HHG radiation properties shows interesting 180° periodic structures. The quantum enhancement of the laser-assisted photo-ionization by femtosecond （1 fs=10^-15 s） and attosecond （1 as=10^-18 s） X-ray pulses and the interference patterns of photo-electron energy spectra are theoretically investigated. Transfer equations are presented for pulse reconstructions. The theoretical root-mean-square time （energy） differences of attosecond pulse reconstructions with different durations are less than 2 as （0,8 eV）. These methods may be developed as basic techniques to access ultra-fast measurements and molecular movie.     

Control for Modified University of Cape Town Process Using Oxidation-Reduction Potential in the Second Anoxic Zone

The aim of this work is to evaluate the feasibility of applying the technology of oxidation-reduction potential(ORP)control on the municipal wastewater treatment system for nitrogen and phosphorus removal.Meanwhile the relation between the optimal ORP(ORP opt)and influent C/N ratio was evaluated,in which the influent chemical oxygen demand(COD)concentration was stabilized at(290±10)mg/L,the influent total phosphorus(TP)concentration was stabilized at(7.0±0.5)mg/L.The results indicated that:(1)the ORP in the second anoxic zone had effect on nitrogen and phosphorus removal capability,and the average percentages of phosphorus uptake in ANO2zone(ηa)increased with increasing ORP,i.e.,increasing from 12.0%at-143 mV to22.0%,30.0%,37.0%,and 45.0%at-123,-111,-105 and-95 mV,respectively;(2)the ORP opt as function of influent C/N ratio could be calculated by the equation:y=252.73e(-x/3.39)-131.01;the maximum percentage of phosphorus uptake in ANO2as function of the ORP opt could be calculated by the equation:y=-0.49 e(x/15.58)+1.51.The ORP opt was the important process control parameter that must be optimized for operation of enhanced biological phosphorus removal(EBPR)system.Moreover,ORP sensor is very simple,and the industrial applications of this strategy is practical.     

Analysis on the change of water potential of <Emphasis Type="Italic">Populus euphratica</Emphasis> Oliv. and <Emphasis Type="Italic">P. Russkii Jabl</Emphasis> under different irrigation volumes in temperate desert zone

The measurement of plant water potential is considered to be a direct approach to confirming the irrigation time in present irrigation systems.In this current study,two shelter forests species in the Junggar Basin (Central Asia),Populus euphratica and P.Russkii Jabl,were studied.We monitored leaf water potential (ψl),stem water potential (ψs) and soil water potential (ψsoil) under different irrigation conditions.The characteristics of the variation in leaf and stem water potential (ψl and ψs) of P.euphratic...     

Slow light between two absorbing resonance in asymmetry double quantum dots

We demonstrate the slow light in double quantum dots (QDs) resonance dispersion material in theory. The slow factor, absorption, and bandwidth are greatly influenced by the energy difference of the two resonance energy. The bandwidth of this system is up to 60 GHz. The 20 ps input signal pulse is delayed by 180 ps (group index of approximately 55) relative to free-space propagation with little broadening in 1 mm dispersion material for the optical communication wavelength. The signal pulse delay can be tuned by the pump pulse.     

RTP-Packets＇ Loss Recovery Scheme Based on Layered Buffer-Routers

This paper introduces an RTP-packets‘ loss recovery scheme in MPEG-4 playback type multicast application model, which is based on retransmission scheme. Through the auxiliary and coordinated buffer playing scheme of layered “buffer-routers”, the RTP-packets‘ loss recovery in limited time is made possible. We consider in the scheme to handle retransmission request with buffer waiting when network congestion occurs. Thus, neither the degree of congestion will be worsened nor the retransmission request will be lost when sending the request to higherlevel buffer router. The RTP-packets‘ loss recovery scheme suggested by us is not only applied to MPEG-4 muhieast application in LAN, but also can be extended to more spacious WAN (wide area network) when user groups comparatively centralize in certain number of local areas.     

An Anti—multipath Frequency Hopped Communication Technique in Shallow—water Acoustic Channels

This paper introduces a frequency-hopped (FH) communication system to anti-intersymbol interferences (ISI) caused by the multipath propagation in shallow-water acoustic channels, and uses high-speed digital signal processor (DSP) and serial ADC (MAX121) chip to demodulate re-ceived signal efficiently based Fast Fourier Transform (FFT) algorithm. The field experimental results show: a data rate of 1Kbit/s with the bit error rates on the order of 10^-4 is denmnstrated at 2000 m in the shallow-water acoustic channel of Xiamen harbor, and the key techniques of the system is analyzed in the paper.     

Speciation of iron in atmospheric particulate matter by EXAFS

In the atmospheric particulate matter (PM), fractions with a particle size of less than 10 μm (PM10) or evenless than 2.5 μm (PM2.5) in aerodynamic diameter can be inhaled into human body and cause serious health problems[1,2]. The influence of the PM on health is not only related to elemental concentrations, but also to its chemical speciation. The study on elemental speciation in atmospheric PM is significant for evaluating toxicity of PM and providing information about the formation a…     

Experimental earth tidal models in considering nearly diurnal free wobble of the Earth＇s liquid core

Based on the 28 series of the high precision and high minute sampling tidal gravity observations at 20 stations in Global Geodynamics Project (GGP) network, the resonant parameters of the Earth‘s nearly diurnal free wobble (including the eigenperiods, resonant strengths and quality factots) are precisely determined. The discrepancy of the eigenperiod between observed and theoretical values is studied, the important conclusion that the real dynamic ellipticity of the liquid core is about 5% larger than the one under the static equilibrium assumption is approved by using our gravity technique. The experimental Earth‘s tidal gravity models with considering the nearly diurnal free wobble of the Earth‘s liquid core are constructed in this study. The numerical results show that the difference among three experimental models is less than 0.1%, and the largest discrepancy compared to those widely used nowdays given by Dehant (1999) and Mathews (2001) is only about 0.4%. It can provide with the most recent real experimental tidal gravity models for the global study of the Earth‘s tides, geodesy and space techniques and so on.     

Precipitation behaviors of X70 acicular ferrite pipeline steel

The morphology, structure, and chemical composition of precipitates in the final microstructure of Nb-V-Ti microalloyed X70 acicular ferrite pipeline steel were investigated using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). Precipitates observed by TEM can be classified into two groups. The large precipitates are complex compounds that comprise square-shaped TiN precipitate as core with fine Nb-containing precipitate nucleated on pre-existing TiN precipitate as caps on one or more faces at high temperature. In contrast, the fine and spherical Nb carbides and/or carbonitrides precipitate heterogene-ously on dislocations and sub-boundaries at low temperature. From the analysis in terms of thermodynamics, EDS and chemical composition of the steel, NbC precipitation is considered to be the predominant precipitation behavior in the tested steel under the processing conditions of this research.     

Luminescence chronology of ＂Old Red Sand＂ in Jinjiang and its implications for optical dating of sediments in South China

A weathered deposit in South China is widespread on the coastal areas of Fujian and Guangdong provinces, China. This deposit consists of slightly cemented, medium- to fine-grained sands, and is characterized by its colors of red, brown red, light reddish brown or dark yellowish orange, and is usually called ＂Old Red Sand＂. The uncertainty in its formation age has been a major obstacle to the study of this type of deposit. In this paper, optically stimulated luminescence （OSL） techniques were used to date the ＂Old Red Sand＂ sediments from Jinjiang, Fujian Province, China. The effect of the geochemical behavior of uranium and thorium in sediment during chemical weathering on estimation of annual dose was investigated. The results show that the change in annual dose due to weathering poses a major problem for the optical dating of such weathered sediments. The optical dating of these weathered deposits will produce erroneous ages if average annual dose during burial cannot be correctly estimated. For the profiles studied, the OSL dates obtained on samples from the upper part do not represent the burial age of the samples. It is highly likely that they are underestimated due mainly to the accumulated radioactive elements as a result of chemical weathering. It is concluded that changes in annual dose due to chemical weathering must be considered when dating similar sediments in South China. With a detailed analysis of the OSL dating results, the chronology of the marine terraces in this area was suggested. The lowest terrace was formed at -3.5 ka and the second terrace was dated to -74 ka. The age of the highest terrace may not be established accurately, but is inferred to be older than the apparent OSL date of -77 ka and so is the Paleolithic artifacts from it.     

Experimental investigation of integrated air purifying technology for bioaerosol removal and inactivation in central air-conditioning system

In this research, high voltage static electricity and ultraviolet technologies were integrated to an air purifying device which can be used to trap and kill airborne bacteria and viruses in central air-conditioning systems. An experimental platform was built to mimic the central air system, in which the efficacy of the newly built device was examined. In addition to the standard physical and chemical tests, bacteriophages were used to simulate airborne viruses in the experimental system. The bacteriophage suspension was aerosolized into the air with ultrasonic wave atomization. The result showed that more than 86% removal efficiency of micro-particles (<10 micron in diameter) were removed after the device was in operation in a building and more than 95% of bacteriophages in the experimental system. It is concluded that the integrated air purifier is suitable for controlling air quality and preventing virus transmission through the central air system.     

Evaluation on Gambiered Guangdong Silk＇s Ecological Properties

To evaluate gambiered Guangdong silk＇s ecology properties, the raw materials ecology, production ecology and use ecology are analyzed; and the safety to human is tested according to GB/T18885 - 2002. Gambiered Guangdong silk is a kind of natural product. All its raw materials are reproducible and degradable natural resources, and it can decompose completely when being discarded. R is comfortable to wear, and easy to clean and dry. It is mainly manufactured by dip-dyeing in dye yam solution, and insolating under the burning sun. The production energy is solar, a kind of clean and reproducible energy. The production process is clean and environmental friendly. There is neither the utilization of synthetic dyestuff and chemical auxiliary, nor the discharge of environment pollutant, and even the dreg of dye yam is used as fuel. The safety test results show that pH value of water extract, heavy metal content （except for Pb content）, color fastness and odor meet the requirements of GB/T18885 - 2002 and Okeo-tex standard 100.