Research at channel level on the effect of LaCl3 on Radish (Raphanus satirus L.) vacuolar membrane

We recorded slow vacuolar (SV-type) channel currents of Radish vacuoles successfully for the first time by using the whole-vacuolar patch-clamp recording mode. SVtrye currents would increase and threshold potentials of activation would shift towards more negative values with the increase of concentrations of cytosolic Ca2+. When 2.5 mmol/L LaCl3 and 4 mmol/L EGTA were added to bath solutions,SV-type currents were suppressed remarkably. Then adding LaCl3 with different concentrations to pipette solutions, we found that LaCl3 with higher concentrations (＞ 4 × 10-7 mol/L)had a strong inhibitory effect on SV-type currents, while LaCl3 with lower concentrations (≤4 × 10-7 mol/L) promoted channel currents. This promoting effect provides an important basis at channel level for researching further the effects of rare earth on physiological activities of plants and the production-increase effects of rare earth fertilizers on crops.``     

Determination of some carbonyl carboxylic acids using chemiluminescent reaction of Ru(bipy)3 2+−Ce(IV)

A coupled chemiluminescence method for the determination of some carboxylic acids was developed, based on their enhancement the chemiluminescence light emission of the reaction of tirs (2,2′-bipyridine) ruthenium(II) and Ce(IV) in sulfuric acid medium. The conditions for their determination were optimized. The following detection limits were obtained: oxalic acid, 2.67×10⁻⁸ mol/L; propandioic acid, 1.20×10⁻⁶ mol/L; pyruvic acid, 1.35×10⁻⁸ mol/L; citric acid, 5.10×10⁻⁸ mol/L; barbituric acid, 2.48×10⁻⁷ mol/L. The proposed method was successfully applied to determination of oxalic acid. The coupled chemiluminescent reaction mechanism and rate equation are proposed. Foundation item: Supported by the National Natural Science Foundation of China and the Natural Science Foundation of Hubei Province Biography: HAN He-you (1962-), male, Associate professor, phD, graduate candidate     

Study of the voltammetric behavior of heme and its direct analysis application

The electroanalytical method of ferriheme was studied by linear sweep voltammetry in medium of 0.05 mol/L Tris+0.05 mol/L NH₃−NH₄Cl buffer at hang mercury drop electrodes (HMDE). Heme exhibits two pair reversible redox peaks and one irreversible peak. The cathodic peak potentials are−;0.236 V, −0.422 V and −1.408 V respectively. The first and the third peaks can be used for directly quantitative determination of heme concentrations. The peak currents are good linear relationship with heme concentration in ranges of 3×10⁻⁶–6×10⁻⁵ mol/L and 3×10⁻⁷–1.5×10⁻⁵ mol/L respectively. Supported by the National Natural Science Foundation of China Lju Huihong: born in 1965, Lecturer. Visiting scholar from Xiangyang Teacher’s College, Hubei, 441053     

Degradation of 2, 4-D acid using Mn2+ as catalyst under UV irradiation

In this paper, the oxidative degradation of 2, 4-dichlorophenoxyacetic acid (2, 4-D) using Mn²⁺/H₂O₂ reagent under UV irradiation was studied. The results show that 2, 4-D was degraded more completely in Mn²⁺/H₂O₂ solution than traditional Fenton solutions. The effects of the concentration of Mn²⁺, H₂O₂ and pH were also investigated. And under the optimal condition of 1.48×10⁻⁴ mol/L, 8.99×10⁻⁵ mol/L and pH 3.38, the formation of ·OH was the most, both the decomposition rate of H₂O₂ and the degradation rate of 2, 4-D were the fastest. In addition, the photoreaction process was monitored using spin-trapping electron paramagnetic resonance (EPR), and the results indicated that the oxidative process was predominated mainly by the hydroxyl radical (·OH) gennerated in the system. Biography: HUANG Yingping (1964–), Professor, Ph. D., research direction: pollution ecology and water pollution control.     

Effect of Cl- on photosynthetic bicarbonate uptake in two cyanobacteria Microcystis aeruginosa and Synechocystis PCC6803

Photosynthetic inorganic carbon utilization was investigated in two cyanobacteria Microcystis aeruginosa and Synechocystis PCC6803 grown in standing culture. Photosynthetic rates for the two algae reached about 10 times the theoretical CO₂ supply rate at low dissolved inorganic carbon (DIC) of 100 μmol/L, and the rates were unaffected by the addition of 20 mmol/L Na⁺, indicating that the two algae possessed Na+-independent HCO^-₃ utilization for photosynthesis under low DIC. Their photo- synthetic rates at low DIC were inhibited by higher Cl^- and the degrees of inhibition were increased with the rise of CI^- concentration, and in the presence of Diphenylamine-2-carboxylate (DPC), a reported Cl^- channel inhibitor, the rates decreased by 74%－82%, implying that putative DPC-sensitive Cl^- channels participate in Na+-independent HCO₃^- uptake for photosynthesis. The experiment of intracellular 14C-DIC accumulation for photosynthesis showed that internal DIC pools decreased by about 80% with 200 μmol/L DPC and by 64%－70% with 100 mmol/L Cl^-. The experiment of chlorophyll a fluorescence quenching showed that initial rates and extents of fluorescence quenching obviously decreased with 200 μmol/L DPC or 100 mmol/L Cl^-. The two experiments gave further evidence that putative DPC-sen- sitive Cl^- channels participate in Na+-independent HCO^-₃ uptake for photosynthesis in the two algae grown in standing culture.     

HPLC determination of ascorbic acid using luminol-Cu (II) chemiluminescence-application to the analysis of Juice beverage

The chemiluminescence (CL) of luminol-Cu (II) was applied to HPLC determination of ascorbic acid, which was separated by a C₁₈ reverse-phase column with a mobile phase of 0.25 mol/L HAc. The eluted ascorbic acid was mixed with 0.3 mmol/L luminol and 0.05 mol/L CuSO₄. The light emission from the reaction of Cu(II) oxidized ascorbic acid and luminol was detected by a modified luminometer. The detection limit was 3.6×10⁻⁶ mol/L for ascorbic acid at aS/N ratio of 3, and the linear calibration range was 2×10⁻⁴–2×10⁻³ mol/L. The relative standard deviation for 5 replicate injections of 1×10⁻³ mol/L ascorbic acid was calculated as 4.3%. The method was successfully applied to determination of ascorbic acid in juice beverage. Foundation item: National Natural Science Foundation of China (29605001) Biography: Wu Feng-wu(1963-), male, research direction: analytical chemistry.     

Electrocatalytic oxidation of H<Subscript>2</Subscript>O<Subscript>2</Subscript> at a carbon paste electrode modified with a nickel (II)-5, 11, 17, 23-tetra-tert-butyl-25, 27-bis(Diethylcarbamoylmethoxy) calix[4] arene complex and its application

Electrochemical behavior of a carbon paste electrode (CPE) modified with nickel(II)-5, 11, 17, 23-tetra-tert-butyl-25, 27-bis(diethylcarbamoylmethoxy) calix[4]arene (Ni (II)-L) complex and its electrocatalytic activity towards the oxidation of hydrogen peroxide were investigated by cyclic voltammetric technique in a 5.0×10⁻² mol/L NaClO₄+1.0×10⁻³ mol/L NaOH solution. It was found that Ni(II)-L acts as an effective catalyst for the oxidation of hydrogen peroxide. The modified electrode exhibited a linear response over a hydrogen peroxide concentrations in the range of 2.0×10⁻⁵−1.0×10⁻⁴ mol/L with a detection limit as low as 1.0×10⁻⁶ mol/L. The relative standard deviation was 3.5% for 5 successive determinations of H₂O₂ at 1.0×10⁻⁵ mol/L. The modified electrode was used successfully in rainwater analysis. Foundation item: Supported by the Natural Science Foundation of Hubei Province (98J040). Biography: Li Chun ya(1972-), Ph. D. candidate, research direction: electroanalysis and electrosynthesis.     

Organic media enhanced spectrofluorimetric determination of L-ascorbic acid

A novel spectrofluorimetric method for the determination of L-ascorbic acid is proposed. It is based on the inhibition of L-ascorbic acid on the formation of 2,3-diaminophenazine, which is an oxidation product ofo-phenylenediamine catalyzed by laccase. The fluorescence (at λ_cx/λ_cm=464 nm /530 nnm) was enhanced strongly in the presence of organic media. The mechanism ofo-phenylenediamine oxidation reaction catalyzed by laccase in the presence of L-ascorbic acid is discussed. L-ascorbic acid is determined in the ethanol, 1,4-dioxane and acetone over the linear range of 4.0×10⁻⁷≈1.2×10⁻⁴ mol/L, 4.0×10⁻⁷≈8.0×10⁻⁵ mol/L and 4.0×10⁻⁷≈1.0×10⁻⁴ mol/L with a detection limit of 1.20×10⁻⁵ mol/L, 1.19×10⁻⁵ mol/L and 1.24×10⁻⁸ mol/L, respectively. The method has been successfully applied to the simple and rapid determination of L-ascorbic acid in pharmaceuticals and milk powder. Supported by National Natural Science Foundation of China and the Special Funds of State Education Committe for Doctorate Research Huang Zuyun: born in Aug. 1963. Ph.D     

Mechanisms of peroxynitrite-induced [Ca2+]i increase in single neuronal cell

The mechanism of peroxynitrite (ONOO⁻)-induced [ca²⁺]_i increase in single MN9D cell (Dopaminergic neuroblastoma cell line) was studied by using Fura-2 microfluorometric technique. The results show that ONOO⁻ caused a rapid increase of [Ca²⁺]_i when ONOO₋ was puffed to the cell. Removing Ca²⁺ from the bath or using calcium channel antagonist (CdCl₂, Nifedipine) greatly inhibited the [Ca²⁺]_i increase induced by ONOO⁻¹, suggesting that the opening of L-Ca²⁺ channel makes a great contribution to the [Ca²⁺]_i increase. The effect of sulfhydryl reductive agent (DTT) on ONOO⁻-induced [Ca²⁺]_i increase suggests that ONOO⁻-activating L-Ca²⁺ channel is partly related to its oxidative speciality.     

Study on state of terbium ion in liposome by one-order derivative fluorescence quenching method

The state of Tb³⁺ is investigated in liposome. When the concentration of PC is below CMC (critical micell concentration), most of Tb³⁺ is associated with PC, the binding constant is about 3.35×10³ L/mol. When the concentration of PC is beyond CMC, most of Tb³⁺ is dimerized, the dimerization constant is about 3.92×10⁴L/mol. In PC−CH−H₂O system, the binding constant of Tb³⁺−CH complex 2.93×10⁴L/mol is obtained. Biography:Mu Xiao-jing (1974-), female, MS.     

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)     

Laser cooling using anti-stokes fluorescence in Yb3+-doped fluorozirconate glasses

The fluorozirconate glasses ZBLANP (ZrF₄−BaF₂−LaF₃−NaF−PbF₂) doped with different Yb³⁺ concentration were prepared. The Raman spectra and absorption spectra are measured to substantiate the existence of phonon-assisted emission. After analyzing the normalized absorption spectra of samples with different Yb³⁺-doped concentration, we calculated the maximum cooling effect in the 3 wt% Yb³⁺-doped sample pumped at 1 012.5 nm. The corresponding cooling capability is about −4.09 °C/W and the cooling efficiency reaches 1.76%. Foundation item: Supported by the Key Science Foundation of Wuhan (9601P0223) Biography: Xu Tian-ming (1978-), female, Master candidate, research direction: information optics and nonlinear optics.     

Determination of isocarbophos by cathodically sweeping oscilliopolarography

Determination of isocarbophos by cathodically sweeping oscilliopolarography is described. In a 1.0×10⁻⁵ mol/L sodium dodecylbenzene sulfonate (SDS)+0.1 mol/L HAC-NaAC (pH=4.0) buffer medium, isocarbophos and its alkaline hydrolysate exhibited sensitive second derivative wave at −0.50 V and −0.48 V respectively. The peak current was linearly proportional to the concentration of isocarbophos in the range of 5.40×10⁻⁶−1.05×10⁻⁴ mol/L by detecting isocarbophos directly. The detection limit was 3.60×10⁻⁶ mol/L with the relative standard derivation (RSD) of 7.3%. By employing an alkaline hydrolysis, the peak current was linearly proportional to the concentration of isocarbophos in the range from 7.70×10⁻⁷ mol/L to 1.24×10⁻⁴ mol/L, and the detection limit was 5.80×10⁻⁷ mol/L with RSD of 3.1%. The hydrolysis procedure and the electrode reaction were studied by voltammetry. Foundation item: Supported by the Foundation of Chinese-France Cooperation Program on Advanced Research Biography: ZHANG Wu-ming (1929-), female, Professor.     

Passivation process of X80 pipeline steel in bicarbonate solutions

The passivation process of X80 pipeline steel in bicarbonate solutions was investigated using potentiodynamic, dynamic electrochemical impedance spectroscopy (DEIS), and Mott-Schottky measurements. The results show that the shape of polarization curves changes with HCO₃⁻ concentration. The critical ‘passive’ concentration is 0.009 mol/L HCO₃⁻ for X80 pipeline steel in bicarbonate solutions. No anodic current peak exists in HCO^3/− solutions when the concentration is lower than 0.009 mol/L, whereas there are one and two anodic current peaks when the HCO^3/− concentration ranges from 0.009 to 0.05 mol/L and is higher than 0.1 mol/L, respectively. DEIS measurements show that there exist active dissolution range, transition range, pre-passive range, passive layer formation range, passive range, and trans-passive range for X80 pipeline steel in the 0.1 mol/L HCO₃⁻ solutions. The results of DEIS measurements are in complete agreement with the potentiodynamic diagram. An equivalent circuit containing three sub-layers is used to explain the Nyquist plots in the passive range. Analyses are well made for explaining the corresponding fitted capacitance and impedance. The Mott-Schottky plots show that the passive film of X80 pipeline steel is an n-type semiconductor, and capacitance measurements are in good accordance with the results of DEIS experiment.     

Chemiluminescence determination of tetracycline and oxytetracycline in pharmaceutical preparations using Ru (bipy)3 2+-cerium (IV) system

A new chemiluminescence (CL) method for the determination of tetracycline and oxytetracycline is developed, based on the CL reaction of tetracycline and oxytetracycline with Ru (bipy)₃ ²⁺ and Ce (IV). In sulfuric acid medium, the CL emission is generated upon continuous oxidtion of Ru(bipy)₃ ²⁺ by cerium (IV). The emission intensity is greatly enhanced when tetracycline and oxytetracycline are introduced into the reaction system after acid degradation. Under the optimum conditions, the calibration curves are linear over the range of 8.0×10⁻⁸∼4.0×10⁻⁶ mol/L for tetracycline and of 2.0×10⁻⁷∼4.0×10⁻⁵ mol/L for oxytetracycline, with the detection limits are 4.2×10⁻⁸ mol/L for tetracycline and 1.5×10⁻⁷ mol/L for oxytetracycline, respectively. The proposed method was used for the determination of tetracycline and oxytetracycline in pharmaceutical formulations with good results. Foundation item: Supported by the National Natural Science Foundation of China and the Natural Science Foundation of Hubei Province. Biography: HAH He-you (1962), male, Associate profeddor, Ph.D graduate candidate. Present address, Department of Chemistry, Huainan Teacher's College, Huainan.     

Chemiluminescence determination of thiourea using tris (1,10-phenanthroline)-ruthenium (II) KMnO4 system

The light emission produced by thiourea in oxidation process by permanganate in acidic solution in the presence of Ru(phen) ₂ ^{3 +} is used to determine 1.0×10⁻⁵ −1.0×10⁻⁵ mol/L thiourea. The limit of detection is 9.8×10⁻⁹ mol/L and the relative standard deviation is 1.1% for a 1.0×10⁻⁵ mol/L thiourea solution (n=10). The method was applied satisfactorily to the determination of thiourea. Foundation item, Support by Ministry of Education, Wuhan University and Alumni Association of it Biography: Wu Feng-wu(1963-), Male, Ph. D, research direction: analytical chemistry.     

Ca2+ signals induced from calcium stores in pancreatic islet β cells

In single rat pancreatic β cells, using fura-2 microfluorometry to measure [Ca²⁺]i response upon different stimuli, the ways of calcium regulation have been studied. When the extracellular calcium concentration was 2.5 mmol/L, either 60 mmol/L KCl, 20 mmol/L D-glucose or 0.1 mmol/L tolbutamide induced increase in [Ca²⁺]i. Such increase in [Ca²⁺]i was absent when the same stimuli were applied under zero extracellular calcium. These results indicate that the increase of [Ca²⁺]i is induced by the activation of voltage-dependent calcium channels in β cells. The manifold forms of [Ca²⁺]i change induced by glucose imply that the effects of glucose are complex. 5 mmol/L caffeine or 5 mmol/L MCh increase the [Ca²⁺]i, which is independent of the external calcium, suggesting that [Ca²⁺]i can be regulated by Ca²⁺ release from not only the IP₃-sensitive but also the ryanodine sensitive calcium stores in β cells. The latency of Ca responses for IP₃ pathway (5 s) is faster than that for ryanodine pathway (30 s). It is concluded that there are multiple calcium stores in rat pancreatic β cells.     

Determination of epinephrine using poly (neurtral red) modified carbon fibre microelectrodes by anodic stripping voltammetry

Poly(neutral red) film modified carbon fibre microelectrodes offer substantial improvement in voltammetric sensitivity and selectivity towards epinephrine (EP). The poly (neutral red) film was electropolymerized by cycling the potential between −0.8 V and +0.8 V. The anodic stripping voltammetric response for EP was found to be dependent on accumulation time and potential. By using a poly(neutral red) film modified carbon fibre microelectrode with a 1 min preconcentration at −1.2 V in biological phosphate buffer solution (pH=7.4). a good linear relationship between the anodic stripping peak currents and EP concentrations was obtained in the range of 2.0×10⁻⁷⊂2.0×10⁻⁵ mol/L. The detection limit was up to 9.0 ×10⁻⁸ mol/L. Moreover, 400 times higher concentrations of vitamin C did not interfere with the measurement of EP. This method was used for determining EP concentrations in epinephrine hydrochloride injection solution with satisfactory results. Supported by the National Natural Science Foundation of China Tang Xiaorong: born in 1974, Master     

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…     

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.