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.     

Rate constants for the reaction of ozone with <Emphasis Type="Italic">n</Emphasis>-butyl, <Emphasis Type="Italic">s</Emphasis>-butyl and <Emphasis Type="Italic">t</Emphasis>-butyl methyl sulfides

The rate constants for the ozone reactions with n-butyl methyl sulfide （n-BMS, CHaCH2CH2CH2SCH3）, sec-butyl methyl sulfide （s-BMS, CH3CH2（CH3）CHSCHa） and tert-butyl methyl sulfide （t-BMS, （CH3）3CSCH3） were measured using our smog chamber under supposedly pseudo-first-order conditions at 30002 K and 760 Torr. The experimental determined rate constants for n-butyl, s-butyl and t-butyl methyl sulfide are （1.23 ± 0.06）×10-19, （5.08 ± 0.19）×10-20 and （2.26 ± 0.14）×10-20 cm3 molecule-1· s-1, respectively. The reactivity-structure relationship of the reactions was discussed and used to illustrate the mechanism of the ozone reaction with thioethers. The results enrich the kinetics data of atmospheric chemistry.     

Effect of Dy3+on osteogenic and adipogenic differentiation of mouse primary bone marrow stromal cells and adipocytic trans-differentiation of mouse primary osteoblasts

A series of experimental methods including 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) test, alkaline phosphatase (ALP) activity measurement, mineralized function, Oil Red O stain and measurement were employed to assess the effect of Dy³⁺ on the osteogenic and adipogenic differentiation of mouse primary bone marrow stromal cells (BMSCs) and the adipogenic trans-differentiation of mouse primary osteoblasts (OBs). The results showed that Dy³⁺ had no effect on BMSC proliferation at concentrations of 1×10⁻⁸ and 1×10⁻⁵ mol/L, but inhibited BMSC proliferation at other concentrations. Dy³⁺ had no effect on OB proliferation at concentrations of 1×10⁻¹⁰ and 1×10⁻⁹ mol/L, but inhibited OB proliferation at other concentrations. Dy³⁺ had no effect on the osteogenic differentiation of BMSCs at concentrations of 1×10⁻⁹ and 1×10⁻⁷ mol/L, and promoted osteogenic differentiation of BMSCs at other concentrations at the 7th day. The osteogenic differentiation of BMSCs was inhibited by Dy³⁺ at concentration of 1×10⁻⁵ mol/L at the 14th day, but promoted osteogenic differentiation of BMSCs at concentrations of 1×10⁻⁹, 1×10⁻⁸, 1×10⁻⁷ and 1×10⁻⁶ mol/L with the maximal effect at concentration of 10⁻⁶ mol/L. Dy³⁺ promoted mineralized function of BMSCs at any concentration. Dy³⁺ had no effect on adipogenic differentiation of BMSCs at concentration of 1×10⁻⁷ mol/L, but inhibited adipogenic differentiation of BMSCs at other concentrations. Dy³⁺ inhibited adipocytic trans-differentiation of OBs at any concentration, suggesting that Dy³⁺ had protective effect on bone and the protective effect on bone may be mediated by modulating differentiation of BMSCs away from the adipocyte and inhibiting adipocytic trans-differentiation of OBs which may promote differentiation and mineralization of OBs. These results may be valuable for better understanding the mechanism of the effect of Dy³⁺ on pathogenesis of osteoporosis. Supported by the Foundation for Key Program of Ministry of Education of China (Grant No. 208018)     

Spectrofluorimetric method for the determination of triamcinolone acetonide

0　IntroductionTriamcinoloneAcetonide,9 fluoro 11β,2 1 dihydroxy 16α,17[(1 methylethylidene)bis (oxy) ] pregn 1,4 diene 3,2 0 dione,Mris 4 34.4 8(abr.TA ) .Itbelongstoaclassofadrenalcortexhormonedrug ,whosefunctionsareaffectionofsugarmetabolism ,anti inflammationandresistancehypersusceptibilityetc.TAcanbesuitabletorheumatoidarthritisanddermatosissuchashypersusceptibilityandneuropathicdermatitis .ThefunctionsofTAisstrongerandlongerthantriamcinolone[1 ,2 ] .ThecommonmethodsofdetectingTAm…     

Experimental investigation of incremental reactivity of di-tert-butyl peroxide

Large quantities of di-tert-butyl peroxide (DTBP) have been emitted into the troposphere due to human activities. Its role in the atmospheric photochemical reaction has not been understood. This study presents the results of the photochemical reactions of DTBP and NOx, which have been simulated in a self-made smog chamber under the temperature of (29±1)℃. Both the wall decays of ozone and NO2 could be neglected, compared to the results in simulative experiments. The effective intensity of UV light used in the experiments was 1.28×10-3 s-1, which was expressed by the rate constant of NO2 photolysis in purified air. The reaction mechanism was proposed according to our results and reports of other researchers. The maximum values of incremental reactivity (IR) in the three simulative ex- periments were 9.53×10-2, 5.23×10-2 and 3.78×10-2, respectively. The incremental reactivity decreased with the increase of initial concentrations of DTBP. The IR value of DTBP obtained in this study was comparable to that of acetylene reported in our previous research.     

Compression behavior and equation of state of Ni77P23 amorphous alloy

The compression behavior of Ni77P23 amorphous alloy is investigated at room temperature in a diamond-anvil cell instrument using insitu high pressure energy dispersive X-ray diffraction with a syn- chrotron radiation source. The equation of state is determined by fitting the experimental data accord- ing to Birch-Murnaghan equation: -ΔV/V0=0.08606P-3.2×10-4P2 5.7×10-6P3. It is found that the structure of Ni77P23 amorphous alloy is stable under pressures up to 30.5 GPa.     

Vp of muscovite-biotite gneiss up to 950℃ at 400 MPa: Constraints on the origin of abnormal seismic layers in continental crust

Here we present experimental results of compressional wave velocity (Vp) of muscovite-biotite gneiss from Higher Himalayan Crystallines (HHC) at the temperature up to 950℃ and the pressure of 0.1―400 MPa. At 400 MPa, when the temperature is lower than 600℃, Vp decreases linearly with increasing temperature at the rate of (Vp/T)p -4.43×10-4 km/s ℃. In the temperature range of 600―800℃, Vp drops significantly and the signal is degraded gradually due to the dehydration of muscovite and α-quartz softening. When the temperature rises from 800℃ to 875℃, Vp increases and the signals become clear again as a result of the temperature going through the β-quartz range. The experiments indicate that the duration has great influence on the experimental results when temperature is above the dehydration point of biotite. During the first 30 h at 950℃, the Vp decreases substantially from 5.9 to 5.4 km/s and the signal amplitude is attenuated by more than 80%. After the 30-h transition, the Vp and the amplitude of ultrasonic wave signals become steady. The decrease of Vp and attenuation of the signals at 950℃ are associated with the breakdown reactions of biotite. The experiments suggest that the breakdown of muscovite and/or quartz softening can contribute to the low seismic wave velocity in thickened quartz-rich felsic-crust such as what is beneath southern Tibet. Additionally, α-β quartz transition generates a measurable high seismic velocity zone, which provides a possibility of precisely constraining the temperature in the upper-middle continental crust. Our study also demonstrates that duration is a key factor to obtain credible experimental results.     

Piezoelectric immunoassay of thyroidal triiodothyronine

A re-utilizable piezoelectric crystal (PC) immunosensor for thyroidal triiodothyronine (T3) has been developed. The crystal was coated with protein A and then reacted with T3 antibody. T3 could be detected in the range of 0.5×10⁻⁶ g/L to 10.0×10⁻⁶g/L by the, system. Crystal was regenerated by saturating with T3 and subsequent binding of a new anti-T3 antibody layer. The T3 assay could be repeated up to 5 times using each crystal. Supported by the National Natural Science Foundation of China Zha Hongying: born May, 1969, Ph. D.     

Temperature dependence of densities of Sb and Bi melts

The densities of Sb and Bi melts were investigated by an improved Archimedean method. The results show that the density of the Sb melt decreases linearly with increasing temperature,but the density of the Bi melt firstly increases and then decreases as the temperature increases. There is a maximum density value of 10.002 g/cm3 at 310 ℃ ,about 39℃ above the melting point. The temperature depend-ence of the Sb melt is well fitted with the expression ρ =6.8590-5.8105×10-4T,and that of the Bi melt is fitted with ρ =10.3312-1.18×10-3T. The results were discussed from a microstructure viewpoint.     

The impacts of “05.6” extreme flood event on riverine carbon fluxes in Xijiang River

An extreme flood event with a frequency of nearly 200 year occurred in June of 2005 in the Xijiang River, the main trunk stream of the Zhujlang River. Samples were systematically collected during the flood event, and water quality parameters, including total suspended sediment （TSS）, dissolved inorganic carbon （DIC）, dissolved organic carbon （DOC）, and particulate organic carbon （POC） were analyzed, and riverine carbon concentrations associated with its changing pattern through the flood process were discussed. These parameters reflect the changes in basin surface flow and subsurface flow during the flood. This flood event influenced annual flux estimations of POC, DOC, and DIC to great extents. Based on carbon flux estimations for the year 2005 and the flood event （June 21-28） in the Xijiang River, it was found that DIC, DOC, and POC fluxes during ＇05.6＇ flood event are 1.52×10^6g.km^-2.a^-1, 0.24×10^6 g.km^-2.a^-1, and 0.54×10^6 g.km^-2.a^-1, and account for 14.87%, 24.75% and 44.89% of the annual fluxes in 2005, respectively. The results suggested that carbon exports during extreme flood events had great contributions to the total carbon fluxes and composition of various carbon components, being important for accurate estimates of annual carbon fluxes in rivers with frequent floods.     

Preparation of monolayer-assembled fluorescent film and its sensing performances to hidden nitroaromatic explosives

Pyrene was chemically assembled on a glass plate surface in a monolayer manner via spacers containing triethylenetetramine （TETA） subunits. It has been demonstrated that the fluorescence emission of the film is sensitive to the presence of trace amount of nitroaromatic compound （NAC） vapors. As discovered in the present work, the response selectivity of the pyrene-functionalized film depends on the length of the spacer, the vapor pressure of a given NAC, and the quencher size. The film shows faster response to those quenchers which have higher vapor pressure and smaller size. Compared to the film with shorter spacers, the present film with longer flexible spacers shows a slower response to the NACs, but higher selectivity to the quencher size. Additionally, the detection limits to common ex- plosives in vapor phase, 2,4,6-trinitrotoluene （TNT） and 2,4-dinitrotoluene （DNT）, are 7.14×10^-12 and 5.49×10^-11 g·mL^-1, respectively. Further examinations indicated that the sensing process is fully reversible, and the vapors of those common interference such as benzene, toluene, ethanol, and perfume have little effect upon the sensing performances of the film.     

Third-order optical nonlinearities for lanthanum (III) complexes with 1, 10-phenanthroline components

The nonlinear refractive indexesn ₂ for the ethanol solutions of 1, 10-phenanthroline (2.0 × 10⁻³ mol · L⁻¹), [bis(l, 10-phenanthroline) lanthanum (III)] nitrate (1.0 × 10⁻³ mol · L⁻¹), and [nitrato-fluoracil-bis (1, 10_{-phenanthroline}) lanthanum (III) ] nitrate (1.0 × 10⁻³ mol · L⁻¹) are first measured, the third-order nonlinear optical susceptibilities χ(³) and 〈γ〉 are calculated, and the mechanisms of the third-order optical nonlinearities enhanced by lanthanum (III) are discussed preliminarily.     

Investigation of Ru （ phen ）3^2＋-Hydrazine-Ce（Ⅳ） Chemiluminescence System and Its Analytical Application

0 IntroductionThbiep ycroidmipnlee)xru ctahteinoinu mof(Ⅱ r)u t(he Rniuu(mbip,y m)3ai2n +ly) atrnids- t(r2is -,(21’ -,10-phenanthroline)ruthenium(Ⅱ) (Ru(phen)32 +) ,is a kindof sensitive analytical reagent for electrogenerated chemilumi-nescence(ECL) and chemiluminescence(CL) ,on which a par-ticular review has been presented[1]. The earliest publicationon the synthesis of Ru(bipy)32 +appeared in 1936[2], andduringthefollowing30 years ,theinvestigations relatedtothissubstance were only in…     

Helium isotope investigation on magnetic reversal boundaries of loess-paleosol sequence at Luochuan, central Chinese Loess Plateau

Extraterrestrial particles have higher 3He/4He ratios than those of terrestrial sediments ( > 100 Ra versus < 0.03 Ra, where Ra is the 3He/4He ratio normalized to the atmospheric value of 1.4×10?6). The inter- planetary dust particles (IDPs), which are very rich in 3He, continuously bombard the Earth and can accumulate in deposits. IDPs sedimentation rate changes can significantly influence 3He concentration in the Earth surface sediments. Since IDPs are not easy to detect in terrestrial deposits, measuring helium isotopes is a helpful approach to examine changes in IDPs. Helium concentration and helium isotopic composition magnetic substances and the quartz particles were examined for helium concen- tration and helium isotopic ratio. Results show that the 3He/4He ratio and the 3He concentrations of the magnetic substances are clearly higher than those of the bulk samples and the quartz particles, and, the 3He/4He ratio of the extracted magnetic substances is also higher than that of the average level of the Earth’s crust. The higher helium content in the magnetic fractions can be explained by an influx of IDPs.     

Export and remineralization of POM in the Southern Ocean and the South China Sea estimated from 210Po/210Pb disequilibria

Disequilibria between ^210Po and ^210Pb in the upper water and their potential applications as a proxy of particle export and remineralization were examined in the Southern Ocean （station IV3） and the South China Sea （NS44）. ^210po was deficit in surface waters but excessive relative to ^210Pb in subsurface waters. Good positive correlation between ^210Po and particulate organic carbon （POC） indicated deficits and excess of ^210Po resulted from particulate organic matter （POM） export and remJneralization respectively, which was also supported by the decreased δ^13C and increased δ^15N downwards as a result of particle remineralization. On the basis of ^210Po/^210Pb box-model, POC export flux out of the surface waters were 1.2 mmol C. m^-2. d^-1 and 2.3 mmol C. m^-2. d^-1 for station NS44 and IV3, respectively. In the subsurface waters, remineralization fluxes of ^210Po were 0.062 Bq. m^-2.d^-1 and 0.566 Bq.m^-2.d^-1 for station NS44 and IV3 along with the recycle efficiency of 52±26% and 119±52%, respectively. Remineralized fluxes of POM derived from ^210Po and exported POC were 0.6 mmol C.m^-2.d^-1 and 2.7 mmol C. m^-2. d^-1 for NS44 and IV3. This study suggested that ^210Po was a powerful tracer of particle export and remineralization.     

A novel Pd/silicalite-1 composite membrane for hydrogen separation

A novel Pd/silicalite-1 composite membrane supported on the macroporous tubular stainless steel substrate was successfully fabricated by electroless plating at 303 K. The structure, morphology and gaseous permeability of the membrane were detected by X-ray diffractiometry （XRD）, scanning electron microscopy （SEM） and single-gas permeation test, respectively. Results confirm the formation of a thin, smooth, and continuous Pd/silicalite-1 composite membrane. The obtained composite membrane shows a high H2 permeance of 1.15×10^-6 mol. m^-2. s^-1. Pa^-1 with moderate H2 selectivity of 250 for H2/N2 at 773 K, at 0.1 MPa pressure drop, suggesting the potential application for H2 separation.     

Crystal structure and negative thermal expansion of solid solution Lu<Subscript>2</Subscript>W<Subscript>3−<Emphasis Type="Italic">x</Emphasis></Subscript>Mo<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>12</Subscript>

A new series of solid solutions Lu₂W_3−x Mo _x O₁₂ (0.5≤x≤2.5) were successfully synthesized by the solid-state method. Their crystal structure and negative thermal expansion properties were studied using high-temperature X-ray powder diffraction and the Rietveld method. All samples of rare-earth tungstates and molybdates are found to crystallize in the same orthorhombic structure with space group Pnca and show the negative thermal expansion phenomena related to transverse vibration of bridging oxygen atoms in the structure. Thermal expansion coefficients (TEC) of Lu₂W_3−x Mo _x O₁₂ are determined as −20.0×10⁻⁶ K⁻¹ for x=0.5 and −16.1×10⁻⁶ K⁻¹ for x=2.5 but -18.6×10⁻⁶ and −16.9×10⁻⁶ K⁻¹ for unsubstituted Lu₂W₃O₁₂ and Lu₂Mo₃O₁₂ in the identical temperature range of 200 to 800°C. High-temperature X-ray diffraction (XRD) data and bond length analysis suggest that the difference between W-O and Mo-O bond is responsible for the change of TECs after the element substitution in this series of solid solutions.     

The comparative investigation on redox property and second-order nonlinear response of Keggin-type α-[PM12O39NPh]3− (M = W and Mo) and Mo6NPh

Keggin-type phenylimido-polyoxometalates α-[PM₁₂O₃₉NPh]³⁻ (M = W and Mo) have been systematically investigated on the electronic structures, redox as well as nonlinear optical (NLO) properties by density functional theory (DFT). The strong M≡N bond confirmed by natural bond orbital (NBO) analysis comprises one s bond and two π bonds, the same as Mo≡N in [Mo₆O₁₈NPh]²⁻. Furthermore, phenylimido segment effectively modifies the electronic properties of α-[PM₁₂O₃₉NPh]³⁻. On one hand, when enlarging the inorganic cluster from {Mo₆O₁₈} to {PMo₁₂O₃₉}, the energy gap between HOMO and LUMO in α-[PMo₁₂O₃₉NPh]³⁻ decreased, resulting in enormously anodic shift for the reduction potential, while the excitation energy is less and the total second-order polarizability β ₀ is up to 438-3×10⁻³⁰ esu, which is nearly 10 times larger than that of [Mo₆O₁₈NPh]²⁻. On the other hand, when metal W in α-[PM₁₂O₃₉NPh]³⁻ is substituted by Mo, the interaction between Mo and N is enhanced and the redox ability becomes stronger. The β ₀ value for α-[PMo₁₂O₃₉NPh]³⁻ is more than 5 times higher than that of α-[PW₁₂O₃₉NPh]³⁻. It indicates that changing appropriate metal or enlarging the inorganic cluster will improve the redox properties and second-order nonlinear response. Moreover, the electron transition for three compounds mentioned above occurred mainly from organoimido segment (as the electron donor) to polyanion cluster (as the acceptor). As a result, α-[PMo₁₂O₃₉NPh]³⁻ may be a promising candidate for oxidant and nonlinear optical material. Electronic Supplementary Material  Supplementary material is available for this article at and is accessible for authorized users. Supported by National Natural Science Foundation of China (Grant No. 20573016), Training Fund of NENU’s Scientific Innovation Project (Grant No. NENUSTC07017), Science Foundation for Young Teachers of Northeast Normal University (Grant No. 20070304) and Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT)     

Structural dependences of the <Emphasis Type="Italic">η</Emphasis><Superscript>6</Superscript> complexes of 3-amino-9-ethylcarbazole with chromium tricarbonyl fragment on third-order optical nonlinearities

Degenerate four-wave mixing measurements, using the 35 ps pulses at 532 nm, have been employed to investigate the third-order nonlinear optical parameters of two chromium tricarbonyl complexes η6-bonded to 3-amino-9-ethylcarbazole at either the NH2-substituted aryl ring （1） or the unsubstituted ring （2） and their precursor 3-amino-9-ethylcarbazole （AECz）. The second-order hyperpolarizability y of the compounds 1 and 2 were found to be 42.9×10^-31 and 35.9×10^-31 esu, respectively, approximately one order of magnitude greater than AECz. The relation between the molecular structure and second-order hyperpolarizability of the compounds I and 2 was explored in detail based on the three-level model and the density functional theory （DFT） calculation. The theoretical results indicate that the spatial distribution of electron density has the profound role in the third-order nonlinear optical properties.     

Studies on the inclusion complex reaction and fluorescent analytical application of β-cyclodextrin with hymecromone

The inclusion complex reaction condition and the mechanism of β-cyclodextrin with hymecromone have been studied by fluorescent spectrum. The fluorescent intensity and the stability of the system can be qreatly increased in qiven condition, and the formation constant of the inclusion complex reaction has been determined too. The system can be applied to the determination of trace amounts of hymecromone, the maximum fluorescent intensity is obtained with excitation and emission wavelength at 362 nm and 452 nm, respectively. The linear range for hymecromone is 8.0×10⁻⁹ mol·L⁻¹ to 1.0×10⁻⁵ mol·L⁻¹. The detection limit is 1.8×10⁻⁹ mol·L⁻¹. A simple, rapid and highly sensitive fluorimetric method is proposed for the determination of hymecromone. The results obtained are in agreement with those given by an official method. Foundation item: Supported by the National Natural Science Foundation of China (G1999046703) Biography: Luo Zhao-fu(1947-), female, Associate professor.