Simultaneous speciation of inorganic arsenic and antimony in water samples by hydride generation-double channel atomic fluorescence spectrometry with on-line solid-phase extraction using single-walled carbon nanotubes micro-column

A new method was developed for the simultaneous speciation of inorganic arsenic and antimony in water by on-line solid-phase extraction coupled with hydride generation-double channel atomic fluorescence spectrometry (HG-DC-AFS). The speciation scheme involved the on-line formation and retention of the ammonium pyrrolidine dithiocarbamate complexes of As(III) and Sb(III) on a single-walled carbon nanotubes packed micro-column, followed by on-line elution and simultaneous detection of As(III) and Sb(III) by HG-DC-AFS; the total As and total Sb were determined by the same protocol after As(V) and Sb(V) were reduced by thiourea, with As(V) and Sb(V) concentrations obtained by subtraction. Various experimental parameters affecting the on-line solid-phase extraction and determination of the analytes species have been investigated in detail. With 180 s preconcentration time, the enrichment factors were found to be 25.4 for As(III) and 24.6 for Sb(III), with the limits of detection (LODs) of 3.8 ng L^− 1 for As(III) and 2.1 ng L^− 1 for Sb(III). The precisions (RSD) for five replicate measurements of 0.5 μg L⁻¹ of As(III) and 0.2 μg L⁻¹ of Sb(III) were 4.2 and 4.8%, respectively. The developed method was validated by the analysis of standard reference materials (NIST SRM 1640a), and was applied to the speciation of inorganic As and Sb in natural water samples.     

Well-posedness of SDEs with drifts in mixed-norm spaces and driven by mixed-noises

We prove the strong well-posedness for stochastic differential equations driven by partial α-stable noise and partial Brownian noise. The drift coefficients belong to certain mixed-norm spaces, which generalize the known results even for stochastic differential equations with single noise cases.     

A Refined Well-Posedness for the Fourth-Order Nonlinear Schrödinger Equation Related to the Vortex Filament

The Cauchy problem of one dimensional fourth-order nonlinear Schrödinger equation related to the vortex filament is studied. Local well-posedness for initial data in H ^s (?) (s > 1/2) is obtained without conditions ν < 0 and μ ? ν/2 = 0 by the Fourier restriction norm method. The result is a refinement of our previous paper (Huo and Jia, 2005 Huo , Z. , Jia , Y. ( 2005 ). The Cauchy problem for the fourth-order nonlinear Schrödinger equation related to the vortex filament . J. Diff. Eq. 214 : 1 – 35 . [Google Scholar]).     

Starburst substituted hexaazatriphenylene compounds: synthesis, photophysical and electrochemical properties

Starburst-substituted hexaazatriphenylene compounds have been designed and synthesized by introducing various peripheral aryl substituents to the central heterocyclic core. The effects of various substituent groups on the photophysical and electrochemical properties of the substituted hexaazatriphenylene have been investigated. Significant red-shifts of the absorption peak (from 413 nm to 530 nm) and emission peak (from 432 nm to 700 nm) were observed when the electron-donating ability of the aryl substituents was increased, corresponding to a decrease in the band gap from 2.90 eV to 2.05 eV. Introducing bulky substituents with weak electron-donating ability enhances the fluorescence quantum yield from 23% to 87%. In contrast, incorporating aryl substituents with strong electron-donating ability decreases the fluorescence quantum yield. Also, due to the extended conjugation between the aryl substituents and the hexaazatriphenylene core, the reduction potentials of the compounds were reduced and the LUMO levels were thus increased.     

Preparation of bupleurum nasal spray and evaluation on its safety and efficacy

Radix Bupleuri is widely used in traditional medicine for the treatment of fever, pain, and inflammation associated with influenza or the common cold. The essential oil extracted from the herb is generally claimed to play the major role in the efficacious treatment of fever. The purpose of the present study was to formulate an intranasal delivery system for the essential oil in an aqueous solution used in the form of nasal spray. From 450 g Radix Bupleuri was extracted the essential oil in the amount of about 0.2 ml, which was slightly water-soluble and viscous with low-fluidity. In order to dissolve the essential oil evenly in the aqueous solution, tween-80 (TW-80, used in 10% (w/v) solution), propylene glycol (PG) and diethylene glycol monoethyl ether (TC) were selected as the favorable solubilizing agents, whose amount was respectively determined by L16(4(5)) orthogonal design. An aqueous solution with clarity and no ciliotoxicity was prepared when TW-80 8% (v/v), PG 14.4% (v/v) and TC 14.4% (v/v) were added. Employed to evaluate the acute toxicity, the rats grew well and were kept active and healthy within 14 d after an intranasal administration of this preparation at the dose of oil from 10 g Bupleuri/kg (50-fold higher than the clinical dose), indicating that there would be no serious toxicity at the normal dose. Intranasal administration of this preparation to 2 kg rabbits with fever induced by subcutaneous injection of turpentine decreased body temperature markedly (0.5, 0.8 and 1.0 degrees C respectively at the dose of oil from 1, 2 and 4 g Bupleuri/body). In addition, the administration significantly reduced fever in 200 g rats induced by intramuscular injection of colicine suspension (0.6 degrees C at the dose of oil from 0.8 g Bupleuri/body). The results suggest that the formulation of nasal spray for the essential oil from Radix Bupleuri can be potentially effective in the treatment of fever.     

Quantum Euler-Poisson System: Local Existence of Solutions

The one-dimensional transient quantum Euler-Poisson system for semiconductors is studied in a bounded interval. The quantum correction can be interpreted as a dispersive regularization of the classical hydrodynamic equations and mechanical effects. The existence and uniqueness of local-in-time solutions are proved with lower regularity and without the restriction on the smallness of velocity, where the pressure-density is general (can be non-convex or non-monotone).     

The Cauchy Problem for the Generalized Korteweg-de Vries-Burgers Equation in _H

The Cauchy problem for the generalized Korteweg-de Vries-Burgers equation is considered and the local existence and uniqueness of solutions in L^q(0, T;L^p) ∩ L^∞(0, T; \dot{H}^{-s})(0 ≤ s < 1) are obtained for initial data in \dot{H}^{-s}. Moreover, the local solutions are global if the initial data are sufficiently small in critical case. Particularly, for s = 0, the generalized Korteweg-de Vries-Burgers equation satisfies the energy equality, so the initial data can be arbitrarily large to obtain the global solution.     

High-Level Expression and Novel Antifungal Activity of Mouse Beta Defensin-1 Mature Peptide in <Emphasis Type="Italic">Escherichia coli</Emphasis>

Mouse beta defensin-1 (mBD-1) is a cationic 37-amino acid antimicrobial peptide with three conserved cysterine disulfied bonds. It exhibits a broad antimicrobial spectrum, but mBD-1 against Candida albicans (C. albicans) and Cryptococcus neoformans (C. neoformans) is poorly understood. This study describes the mBD-1 gene, the heterologous fusion expression of the peptide in Escherichia coli, and the bioactive assay of released mature mBD-1. By constructing the expression plasmid (pET32a-mBD1), high yields of soluble mBD-1 fusion protein (0.67 g/L) could be obtained in E. coli and cleaved by enterokinase. The digested product was further purified and desalted with the final amount of pure mature mBD-1 being 0.14 g/L. Classical fungi growth inhibition assay showed clear antifungal activity against C. albicans and C. neoformans with IC₅₀ of 5 and 2 μM, respectively. The results show that the mBD-1 control fungal colonization through hyphal induction, direct fungicidal activity, and the activity is suppressed by increasing NaCl concentration. Successful expression of the mBD-1 peptide in E. coli offers a basis for further studying its antifungal mechanisms and may provide significance in developing this peptide to an antifungal drug.     

基于证据意识的物理科学素养的培养--以“力的作用是相互的”教学为例

义务教育物理课程标准指出,物理课程不仅应注重科学知识的传授和技能的训练,而且应注重对学生学习兴趣、探究能力、创新意识以及科学态度、科学精神等方面的培养.基于证据意识的培养,就是培养学生实事求是的科学态度、逻辑严谨的科学思维、勇于创新的科学态度,是培养学生物理科学素养的核心环节.本文以苏科版物理8年级下册第8章第4节“力的作用是相互的”的教学为例,谈谈在物理教学中如何在证据意识下培养学生的科学素养.     

ψ(4040) and ψ(4160) Decays into the Dd± Ds∓$ D_{d}^{\pm } D_{s}^{\mp }$ Pair and the S- D Mixing Effects

The ψ(4040) and ψ(4160) →\(D_{d}^{\pm }D_{s}^{\mp }\) decays are studied with the perturbative QCD approach phenomenologically. It is found that branching ratios for these decays are insensitive to the S-D mixing angle ?? ∈ [?30^°,30^°], and too tiny to be measured in the near future experiments.