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1.
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 HCO3/− solutions when the concentration is lower than 0.009 mol/L, whereas there are one and two anodic current peaks when the HCO3/− 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. 相似文献
2.
Zhenrong Sun Shenyi Wang Yanping Huang Jiyun Lin Liangen Ding Zugeng Wang 《科学通报(英文版)》1998,43(5):399-402
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. 相似文献
3.
Photodynamic therapy (PDT) is a very effective treatment for port wine stains (PWS). To guide and assess PDT treatment, a handheld optical coherence tomography (OCT) probe was designed for real-time imaging of the PWS patient. The system uses a light source with a center wavelength of 1310 nm, -3 dB bandwidth of 90 nm and an optical power of 9 mW. The system also has a spatial resolution of 8 μm (lateral) × 7 μm (axial), an imaging rate of 4 frames per second, and a 102 dB sensitivity. We then demonstrate that the OCT imaging system can clearly distinguish between normal and PWS tissues. Therefore, the system can provide valuable guidance for PDT treatment. 相似文献
4.
Ta-doped In2O3 transparent conductive oxide films were deposited on glass substrates using radio-frequency (RF) sputtering at 300°C. The
influence of post-annealing on the structural, morphologic, electrical and optical properties of the films was investigated
using X-ray diffraction, field emission scanning electron microscopy, Hall measurements and optical transmission spectroscopy.
The obtained films were polycrystalline with a cubic structure and were preferentially oriented in the (222) crystallographic
direction. The lowest resistivity, 5.1×10−4 Ω cm, was obtained in the film annealed at 500°C, which is half of that of the un-annealed film (9.9×10−4 Ω cm). The average optical transmittance of the films was over 90%. The optical bandgap was found to decrease with increasing
annealing temperature. 相似文献
5.
Zhinong Gao Shuxin Tai Qi Zhang Yu Zhao Bo Lü Yushu Ge Li Huang Xiaoyan Tang 《武汉大学学报:自然科学英文版》2008,13(2):227-231
The synthesis and surface activity of gemini surfactants with ester bond as spacer are described. Their critical micelle concentrations (CMC) are much lower than that of conventional surfactants, i.e., 1.62×10^-5, 1.38×10^-5, 1.28×10^-5 mol·L^-1 for gemini Ⅰ, Ⅱ and Ⅲ respectively. Surface tension at the CMC of gemini Ⅰ, Ⅱ and Ⅲ were 36.4, 38.5, 41.2 mN · m^-1. The physico-chemical properties such as Krafft points, foaming abilities and emulsifying power were also investigated. It is found that the title compounds have low Krafft points and show good solubility in water. The gemini surfactants synthesized also exhibit good foaming properties and excellent emulsifying power toward toluene. The foaming abilities and emulsifying power increase with the increase in carbon number of hydrophobic chain, and this might be caused by the sheer viscosity of different gemini surfactant solution. 相似文献
6.
ZHAN Haigang SHI Ping CHEN Chuqun 《科学通报(英文版)》2005,50(23):2770-2777
The recently developed quasi-analytical algorithm (QAA) is a promising algorithm for deriving inherent optical properties from ocean color. Unlike the conventional semi-analytical algorithm, QAA does not need a priori knowledge of the spectral shape of chlorophyll absorption. However, several empirical relations, which may not be universally applicable and can result in low noise tolerance, are involved in QAA. In this study, the Bayesian inversion theory is introduced to improve the performance of QAA. In the estimation of total absorption coefficient at the reference wavelength, instead of empirical algorithms used in the QAA, the Bayesian approach is employed in combination with an optical model that uses separate parameters to account explicitly for the contribution of molecular and particle scatterings to remote sensing reflectance, a priori knowledge produced by the QAA, the Akaike's Bayesian information criterion (ABIC) for choosing the optimal regularization parameter, and genetic algorithms for global optimization. Coefficients at other wavelengths are then derived using an empirical estimate of particle backscattering spectral shape. When applied to a simulated dataset synthesized by IOCCG, the Bayesian algorithm outperforms QAA algorithm, especially in higher chlorophyll concentration waters. The root mean square errors (RMSEs) between the true and the derived α(440) and bb(440) are reduced from 0.918 and 0.039 m^-1 for QAA-555 to 0.367 and 0.023 m^-1 for Bayes-555, 0.205 and 0.007 m^-1 for QAA-640 to 0.092 and 0.005 m^-1 for Bayes-640, and 0.207 and 0.007 m^-1 for QAA-blending to 0.096 and 0.005 m^-1 for Bayes-blending. Results of noise sensitivity analysis show that the Bayesian algorithm is more robust than QAA. 相似文献
7.
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) 相似文献
8.
Peng Lin Zhang HuiMin Ren ZhaoFang Mu Ling Shi RuiLiang Chang LiPing Li Fan 《科学通报(英文版)》2009,54(8):1422-1425
Carbon isotopic compositions of atmospheric Non-methane Hydrocarbons(NMHCs) in the urban areas of Taiyuan and Lanzhou in summer were reported and the sources of NMHCs are discussed.Carbon isotopic ratios(δ 13C) of vehicle exhaust,coal-combustion exhaust,fuel volatiles and cooking exhaust were also measured with thermal desorption-gas chromatography-isotope ratio-mass spectrometry(TD-GC-IR-MS).δ 13C values of NMHCs in the urban areas of Lanzhou and Taiyuan range from-32.3‰ to-22.3‰ and from-32.8‰ to-18.1‰.δ ... 相似文献
9.
QIN Yimin PAN Nina ZOU GuolinCollege of Life Sciences Wuhan University Wuhan Hubei China 《武汉大学学报:自然科学英文版》2006,11(2):432-436
0Introduction Porphyrinderivativeshavebeenusedasphotosensitizersinphotodynamictherapy(PDT),anewapproachdevel opedforthetreatmentofcancer[1].Cationwater solublepor phyrinsareofconsiderableinterestowingtotheirpossiblebio medicalapplications[2].Inwhich,theinhibiteffectonthe growthmetabolismofE.coliandcancercellHL60ofmeso tetra(4N ethylacetatepyridyl)porphyrin(H2NEAE pp)and itsZn(Ⅱ)complexform(ZnNEAE pp)havebeenrecentlyin vestigated[3,4].Toenhancetumor locationandanticancerac tivitiesofdr… 相似文献
10.
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. 相似文献
11.
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. 相似文献
12.
A rapid and sensitive on-line preconcentration method for spectrophotometric determination of chromium (VI) in nature water
is described. Preconcentration and determination are based on (i) the quantitative and fast adsorption of chromium (VI) on
the high surface area nanometer-size TiO2 (anatase) powders, which prepared by a sol-gel method from hydrolysis of TiCl4 and (ii) the quantitative and reproducible elution of Cr (VI) by 2.0 mol·L−1 HCl. A mini-column system for preconcentration is developed, Cr(VI) on the mini-column is eluted and merged with a stream
water and DPCB (1,5-diphenylcarbazide) as the chromogenic reagent. The proposed system permits throughputs of 6 sample h−1 (0.001 μg·mL−1 Cr(VI)) or 20 sample h−1 (0.1 μg·mL−1 Cr(VI)). The preconcentration factor is 55. The detection limit is 0.8 ng · mL−1 Cr(VI). The reproducibility is satisfactory with a relative standard deviation of less than 3.35% (0.01 μg·mL−1 Cr(VI),n=5).
Supported by the National Natural Science Foundation of China
Ma Wanhong: born in 1961, Ph. D. Graduate student, Associate professor 相似文献
13.
An electrochemical method for the simultaneous determination of lead(II) and Cadmium(II) with a calix[6]arene modified carbon
paste electrode (CPE) has been developed. Pb2+ and Cd2+ were accumulated at the surface of the modified electrode via formation of chemical complexes with calix[6]arene, and reduced
at 1.40 V. During the following anodic potential sweep, reduced lead and cadmium were oxidized, and two well-defined striping
peaks appeared at about −0.60 V and −0.84 V. Compared with a bare carbon paste electrode, the calix[6]arene modified CPE greatly
improves the sensitivity of determining lead and cadmium. The stripping peak currents change linearly with the concentration
of Pb2+ 3.0×10−8–8.0×10−6 mol·L−1 and with that of Cd2+ 6.0×10−8–1.0×10−5 mol ·L−1. The detection limits of Pb2+ and Cd2+ are found to be 8.0×10−9 mol·L−1 and 2.0×10−8 mol·L−1, respectively. The modified carbon paste electrode was applied to determine trace levels of lead and cadmium in water samples.
Comparing with that of atomic absorption spectrometry, the results suggests that the calix[6]arene modified CPE has great
potential for the practical sample analysis.
Foundation item: Supported by the National Natural Science Foundation of China (60171023)
Biography: JI Xiao-bo (1980-), male, Master, research direction: electroanalytical chemistry. 相似文献
14.
Wu Yun-hua Fei Jun-jie Dang Xue-ping Hu Sheng-shui College of Chemistry Molecular Sciences Wuhan University Wuhan Hubei China 《武汉大学学报:自然科学英文版》2004,9(3):366-370
0 IntroductionDetectionofammoniumionisveryimportantinmanyfields,suchashealthcare,agriculture ,cultivationandenviron mentalpollutioncontrol.Severalanalyticalmethodshavebeende velopedforammoniumdeterminationincludingionchromatography ,spectrophotometry,fluorimetryandchemiluminescence .MostofthemarebasedonspectrophotometryusingtheBerthelot reactionbetweenammonium ,phenol,andhypochloriteleadingtothefor mationofanindophenoldye[1 ] .Thereactiontimeisaboutanhour,andsomedissolvedorganicnitrogencompo… 相似文献
15.
Aniline was polymerized in dilute aqueous squaric acid and the polyaniline (PAn) was doped with 10−1–10−3 mol/L of squaric acid. The corresponding electrical conductivity of the PAn is 10−1–10−2 S ⊙ cm−1. The solubility of the doped PAn has been improved in common polar organic solvents. The FTIR and UV—Vis spectra show that
the PAn has the structure of both quinone and imine.
Supported by the National Natural Sciences Foundation of China
Zhan Caimao: born in 1948, Associate professor 相似文献
16.
The fluorescence intensity of the europium (III)-tetracycline (TC) complex can be greatly increased by TOPO, TBP, TTA and
surfactans, among which TOPO showed the greatest enhancement. The formation of ternary complex was proposed to be responsible
for the fluorescence enhancement. The Eu (III)-TOPO-TC system can be applied to the determination of trace amounts of tetracycline
in urinous sample; the maximum fluorescence intensity was obtained in the pH range of 8.2∼9.5 with excitation and emission
wave-lengths at 396 nm and 616 nm, respectively. The linear range for tetracycline is 6.0×10−9−5.0×10−7 mol·L−1. The detection limit is 2.0×10−9 mol·L−1(SNR=3). Experimental conditions and the mechanism of the enhancement effect are discussed.
Supported by National Natural Science Foundation of China
Huang Chunbao: born in 1958, Associate professor 相似文献
17.
Fibrates are widely used for the treatment of dyslipidemia.However,the contributions of the phase I and phase II metabolic pathways to the clearance of fibrates are unclear.In this study,we investigated the metabolism of gemfibrozil(Gem) ,clofibric acid(CA) ,fenofibric acid(FA) and bezafibrate(Beza) by cytochrome P450s(P450s) and UDP-glycosyltransferases(UGTs) using a substrate depletion approach.We also compared the metabolic characteristics of rat liver microsomes(RLM) and human liver microsomes(HLM) .The intrinsic clearance rates mediated by P450s,UGTs and both were 172 ± 22,643 ± 26,798 ± 103 μL min-1 mg-1,respectively,for Gem and 43 ± 11,88 ± 12,119 ± 15 μL min-1 mg-1,respectively,for CA in RLM.The fractions metabolized by P450s and UGTs in RLM were 22% and 81% for Gem,36% and 74% for CA.The P450-and UGT-mediated depletion rates for Gem were 303 and 1607 nmol min-1 mg-1 in RLM versus 86 and 243 nmol min-1 mg-1 in HLM.The corre-sponding rates for CA were 1.1 and 1.7 nmol min-1 mg-1 in RLM versus 0.025 and 0.038 nmol min-1 mg-1 in HLM.Accordingly,both P450s and UGTs substantially contribute to the clearance of Gem and CA,with UGTs playing a greater role.To avoid un-der-estimating the impact of these pathways,it is necessary to measure NADPH-and UDPGA-dependent metabolism.Although the fractions of these two pathways in RLM and HLM were similar,the depletion rate of Gem and CA in RLM was higher than that in HLM.The metabolism of FA and Beza by P450s and UGTs was too low to calculate intrinsic clearance in both RLM and HLM.These results indicate that fibrates are metabolized via similar pathways in rats and humans,and it is applicable to use RLM to predict the clearance of fibrates in human. 相似文献
18.
Determination of omethoate by cathodically sweeping oscillopolarography is described. The product of the alkaline hydrolysis
exhibited a sensitive second derivative wave at −0.50 V (vs. SCE) in a 1.0 ×10−5mol/L sodium dodecylbenzene sulfonate (SDBS)+0.1 mol/L HAc-NaAc (pH 4.0) buffer. The peak current was linearly proportional
to the concentration of omethoate in the range from 6.4×10−7 to 5.1×10−5 mol/L. The detection limit is 2.0×10−7 mol/L with the relative standard derivation (RSD) of 3.5%. The hydrolysis procedure and the electrode reaction were studied
by voltammetry.
Supported by the Foundation of Chinese-Franch Cooperation Programme on the Advanced Research
Wang Yu: born in 1964. Lecturer. Cangzhou Teacher’s College, Cangzhou, Hebei, 061001 相似文献
19.
Mo isotopes along with Nd isotopes and other geochemical characteristics of the Phanerozoic clastic sediments from the northern margin of the Yangtze block were analyzed by MC-ICP-MS and some other techniques, spanning the period from Cambrian to Jurassic. The δ 98Mo values and εNd(t ) in these sedimets were observed to exhibit a large range of variation (?0.65‰―+1.87‰, ?1.46―?10.90, respec-tively). Specifically, the sample from Late Permian Maokou Formation has relatively positive values in both δ 98Mo and... 相似文献
20.
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 λcx/λcm=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 相似文献