吡啶离子液体与水混合体系中蒽醌-2-磺酸钠的激光闪光光解机理

利用激光闪光光解技术研究了蒽醌-2-磺酸钠(AQS)在吡啶离子液体N-丁基吡啶四氟硼酸盐([BPy][BF₄])与水(H₂O)混合体系中的光化学反应过程. 实验结果表明,AQS的激发三重态(³AQS^*) 会与H₂O快速反应,不断增加[BPy][BF₄]在混合体系中的体积比(V_IL),瞬态吸收光谱发生了很大变化. 510 nm附近的瞬态吸收带变化最大,在0< V_IL< 0.1时,吸光度会随着[BPy][BF₄]的增加而增加;而在V_IL>0.1时,吸光度则随着比例的增加而减小. 然而380 nm附近吸收带的吸光度却一直在增加. 通过拟合近似地得到了瞬态物种B和³AQS^*的表观动力学参数. 另外还讨论了³AQS^* 与阳离子之间的夺氢反应,通过对350~420 nm处光谱图的分析,推断出这一范围的瞬态吸收光谱是³AQS^*与AQSH^·的叠加谱. 在混合体系中,³AQS^*分别与H₂O和[BPy][BF₄]的反应是一对竞争反应. 还发现在高浓度的离子液体环境下,体系的整体反应速率会减弱.     

New measurements of the water vapor continuum in the region from 0.3 to 2.7 THz

We present a spectroscopic study of the water vapor continuum absorption in the far-IR region from 10 to 90 cm⁻¹ (0.3-2.7 THz). The experimental technique combines a temperature-stabilized multipass absorption cell, a polarizing (Martin-Puplett) interferometric spectrometer, and a liquid-He-cooled bolometer detector. The contributions to the absorbance resulting from the structureless H₂O-H₂O and H₂O-N₂ continua have been measured in the temperature range from 293 to 333 K with spectral resolution of 0.04-0.12 cm⁻¹. The resonant water vapor spectrum was modeled using the HITRAN04 database and a Van Vleck-Weisskopf lineshape function with a 100 cm⁻¹ far-wing cut-off. Within experimental uncertainty, both the H₂O-H₂O and H₂O-N₂ continua demonstrate nearly quadratic dependencies of absorbance on frequency with, however, some deviation near the 2.5 THz window. The absorption coefficients of 3.83 and 0.185 (dB/km)/(kPa THz)² were measured for self- and foreign-gas continuum, respectively. The corresponding temperature exponents were found to be 8.8 and 5.7. The theoretically predicted foreign continuum is presented and a reasonable agreement with experiment is obtained.     

Radionuclide 188Re-Loaded Photothermal Hydrogel for Cancer Theranostics

Herein, an injectable photothermal hydrogel system containing a therapeutic radionuclide ¹⁸⁸Re is studied for combined radioisotope therapy and photothermal therapy (PTT) of cancer. A dopamine-conjugated poly(α,β-aspartic acid) copolymer (PDAEA) is used to trigger a sol–gel phase transition in mixture with Fe³⁺ ions, rapidly forming a gel by simply mixing PDAEA and FeCl₃ phosphate buffer saline solutions. The injectable hydrogel exhibits strong near-infrared light absorbance and can efficiently convert light into a heating effect for local PTT treatment. The obtained hydrogel possesses a porous 3D microstructure, and can be utilized for radionuclide loading. After the Na¹⁸⁸ReO₄ loading, the hydrogel is intratumorally injected into the tumor of mice bearing 4T1 murine breast cancer cells for studying the tumor retention and therapeutic efficiency. In vivo results show that Na¹⁸⁸ReO₄-loaded hydrogel exhibits significantly longer time in the tumor sites than that of free Na¹⁸⁸ReO₄. The tumor growth of mice treated with Na¹⁸⁸ReO₄-loaded hydrogel under near-infrared radiation is significantly inhibited compared with control groups. Therefore, the results show that the developed strategy using an injectable and biocompatible hydrogel may promote the applications of radioisotope therapy and photothermal therapy for cancer.     

Using polyatomic primary ions to probe an amino acid and a nucleic base in water ice

In this study on pure water ice, we show that protonated water species [H₂O]_nH⁺ are more prevalent than (H₂O)_n⁺ ions after bombardment by Au⁺ monoatomic and Au₃⁺ and C₆₀⁺ polyatomic projectiles. This data also reveals significant differences in water cluster yields under bombardment by these three projectiles. The amino acid alanine and the nucleic base adenine in solution have been studied and have been shown to have an effect on the water cluster ion yields observed using an Au₃⁺ ion beam.     

Design of an optical sensor array for hydrocarbon monitoring

Evanescent field optical sensors are accurately designed for hydrocarbon monitoring in water. Various kinds of waveguide sensors are optimized by considering a polydimethylsiloxane polymeric overlay as sensor region. The simulation results suggest that the selection of a suitable waveguide cross section can enhance the sensor performance. In particular, the hollow waveguide sensor exhibits very intriguing performance, the absorbance being quite linear with respect to the contaminant concentration. For the toluene pollution the absorbance exhibits a slope S_TE^A = 2.52 ×10^-2 ppm^-1{S_{\rm TE}^{A} =2.52 \times 10^{-2}\,{\rm ppm}^{-1}} for a waveguide reference length L = 1.18 mm. In order to simultaneously detect different pollutants in water such as toluene, benzene, chlorobenzene and ethilbenzene, an array of four miniaturized hollow waveguide sensors is designed.     

Quantitative O imaging towards oxygen consumption study in tumor bearing mice at 7 T

¹⁷O magnetic resonance imaging (MRI) using a conventional pulse sequence was explored as a method of quantitative imaging towards regional oxygen consumption rate measurement for tumor evaluation in mice. At 7 T, fast imaging with steady state (FISP) was the best among gradient echo, fast spin echo and FISP for the purpose. The distribution of natural abundance H₂¹⁷O in mice was visualized under spatial resolution of 2.5 × 2.5 mm² by FISP in 10 min. The signal intensity by FISP showed a linear relationship with ¹⁷O quantity both in phantom and mice. Following the injection of 5% ¹⁷O enriched saline, ¹⁷O re-distribution was monitored in temporal resolution down to 5 sec with an image quality sufficient to distinguish each organ. The image of labeled water produced from inhaled ¹⁷O₂ gas was also obtained. The present method provides quantitative ¹⁷O images under sufficient temporal and spatial resolution for the evaluation of oxygen consumption rate in each organ. Experiments using various model compounds of R-OH type clarified that the signal contribution of body constituents other than water in the present in vivo¹⁷O FISP image was negligible.     

An isotopic labeling study of the diffusion mechanism during oxidation of Si(100) in water vapor by successive oxidation

The diffusion mechanism during the wet oxidation of Si(100) at 1373 K was investigated by successive oxidations finally containing isotopic water. SiO₂ was first thermally grown on Si in non-labeled oxidizing ambient (dry O₂ or H₂O) followed by isotopic water (H₂¹⁸O) to trace ¹⁸O species in SiO₂. The distributions of ¹⁶O and ¹⁸O in the oxide film were analyzed by means of secondary ion mass spectroscopy (SIMS). SIMS depth profiles show that there was a wide overlap of both isotopes (¹⁸O and ¹⁶O) throughout the SiO₂ layer, no matter whether the first oxidation step was carried out in dry O₂ or H₂O, and the concentration gradient of ¹⁸O decreased with increasing oxidation time at the second oxidation step by H₂¹⁸O. The results suggest that the diffusion mechanism in SiO₂ during water vapor oxidation is exchange diffusion; H₂O related oxidizing species diffuse through the network with significant exchange with the pre-existing oxygen in it.     

On Line Dissolution of ZnS For Sulfide Determination in Stabilized Water Samples with Zinc Acetate,Using Spectrophotometry by Methylene Blue Method

Abstract

Stabilization of sulfide as zinc sulfide is a strategy widely used in batch analysis of this ion in water. A FIA/spectrophotometry system to determine sulfide in stabilized water samples is proposed in this paper. The methodology is based on the formation of methylene blue by the reaction of H₂S with a mixture of Fe³⁺ solution and N,N-dimethyl-p-phenylenediamine (DMPD) in acidic medium. In the system, the sample (480 μL) containing stabilized sulfide (as ZnS slurry) is injected in a carrier stream formed by mixing acidic Fe³⁺ and DMPD. In the reactor coil of 1280 μL, the sulfide is drifted by acid used in the preparation of solutions, releasing H₂S that reacts with Fe³⁺ and DMPD forming methylene blue. The absorbance is measured at 662 nm. The performance of the FIA system was optimized in relation to chemical and flow parameters. The stability of the solutions were studied throughout the period of the experiment. The results did not show any loss of sulfide over a 7 day period. However, in complex matrices an analysis by using the standard addition method is recommended. The analysis of effluent sample through the time showed good agreement between the results obtained each day. The developed system presented the following figures of merit: detection limit of 50 μg L^?1; RSD of 6% at 0.5 μg mL^?1 (using ultrasonic homogenization) and analytical throughput of 60 samples per hour.     

V+注入锐钛矿TiO2第一性原理研究

用金属离子注入方法在锐钛矿TiO₂薄膜中掺杂了V⁺，采用全势线性缀加平面波方法计算了锐钛矿TiO₂及V⁺掺杂TiO₂超原胞的电子结构，通过紫外-可见吸收光谱测试方法检测了注入不同剂量的V⁺对TiO₂薄膜吸收光谱的影响.理论计算和实验结果表明，锐钛矿TiO₂薄注入V⁺后，带隙宽度变小，吸收光谱发生红移，并且TiO 关键词： +注入')" href="#">V⁺注入 2')" href="#">TiO₂ 全势线性缀加平面波方法 能带结构     

Framework and extra-framework aluminium in wet ion exchanged Fe-ZSM5 and the effect of steam during the decomposition of N2O

The role of extra-framework and framework aluminium in wet-ion exchanged Fe-ZSM5 has been studied using ²⁹Si NMR and ²⁷Al triple quantum magic angle spinning (3QMAS) NMR. A series of samples were studied, the parent material, the wet ion exchanged Fe-ZSM5 and Fe-ZSM5 that has been used in the decomposition of N₂O with varying reaction conditions. Various framework and extra-framework aluminium species have been identified. It was found that cationic Fe species prefer to replace the Brønsted acid protons in their charge balancing role at those aluminium sites associated with the largest quadrupolar product. The framework aluminium atoms that pertain to the smaller quadrupolar product, which are either charge balanced by extra-framework aluminium or a proton, are much less prone to exchange. In the catalytic decomposition of N₂O it seemed that water present in small amounts enhances the catalytic activity. However, water also decreases the long term stability and performance by dealuminating the zeolite framework. With a high amount of water present, Fe-ZSM5 was destabilised and catalytically inferior.     

A sonochemical synthesis of cyclodextrin functionalized Au-FeNPs for colorimetric detection of Cr6+ in different industrial waste water

This paper describes a simple, selective and sensitive colorimetric sensing of Cr⁶⁺ ions using β-Cyclodextrin (β-CD) functionalized gold-iron nanoparticles (β-CD/Au-FeNPs). The sonochemically synthesized nanoparticles are winered in colour due to the SPR band of β-CD functionalized bimetalic nanoparticles Au-FeNPs. The capping and stabilizing of Au-FeNPs by redox β-CD is confirmed by FT-IR. The particles are spherical in shape and it posses the effective diameter of 18–20 nm. Under optimized conditions, in the presence of Cr⁶⁺ the wine red Au-FeNPs solution was turned to colourless, accompanying the broadening and red shifting of SPR band. The ratio between the absorbance wavelength at 573 nm to 535 nm (A₅₇₃/A₅₃₅) is linearly correlated with the Cr⁶⁺ concentrations ranging from 50 nM to 500 nM, with a detection limit of Cr⁶⁺ of 2.5 nM was achieved for the first time using β-CD/Au-FeNPs by spectrophotometry. The selectivity of the β-CD/Au-FeNPs towards other interfering metal ions. Finally the proposed method has been successfully employed for the determination of Cr⁶⁺ ion in various industrial waste water with good recoveries.     

Measurement of regional cerebral glucose uptake by magnetic resonance spin-lock imaging

Purpose

The regional uptake of glucose in rat brain in vivo was measured at high resolution using spin-lock magnetic resonance imaging after infusion of the glucose analogue 2-deoxy-d-glucose (2DG). Previous studies of glucose metabolism have used ¹³C-labeled 2DG and NMR spectroscopy, ¹⁸F-labeled fluorodeoxyglucose (FDG) and PET, or chemical exchange saturation transfer (CEST) MRI, all of which have practical limitations. Our goal was to explore the ability of spin-lock sequences to detect specific chemically-exchanging species in vivo and to compare the effects of 2DG in brain tissue on CEST images.

Methods

Numerical simulations of R_1p and CEST contrasts for a variety of sample parameters were performed to evaluate the potential specificity of each method for detecting the exchange contributions of 2DG. Experimental measurements were made in tissue phantoms and in rat brain in vivo which demonstrated the ability of spin-lock sequences for detecting 2DG.

Results

R_1p contrast acquired with appropriate spin-lock sequences can isolate the contribution of exchanging protons in 2DG in vivo and appears to have better sensitivity and more specificity to 2DG–water exchange effects than CEST.

Conclusion

Spin-lock imaging provides a novel approach to the detection and measurement of glucose uptake in brain in vivo.     

Synthesis,vibrational and UV–visible studies of sodium cadmium orthophosphate

In this paper, NaCdPO₄ orthophosphate was prepared by solid-state reaction technique at high temperature. Structural, vibrational and optical properties have been investigated. X-ray powder diffraction analysis revealed that the titled compound crystallizes in the orthorhombic system with Pmnb space group. Vibrational study by means of Raman and FTIR spectroscopies confirms the existence of the (PO₄)^3? functional group. Optical properties were recorded at room temperature using UV–visible spectroscopy in the spectral range (200–800) nm. The UV–Vis absorption bands are attributed to the charge transfer from the oxygen ligands to the central phosphate atom inside the PO₄ ^3? groups. The optical absorbance was measured also to determinate the optical band gap using Kubelka–Munk function. The dispersion parameters (E₀ and E_d) of this compound were estimated using the Wemple Di-Domenico model.     

Preparation and photovoltaic property of a new hybrid nanocrystalline SnO2/Polypyrrole p–n heterojunction

Hybrid photovoltaic structures based on transparent conductive SnO₂ and electrically conductive polypyrrole (PPy) were prepared. Nanocrystalline SnO₂ is considered an n-type barrier and window layer on p-type PPy layer in cell structures. The surface morphology and thickness of the layers were studied using scanning electron microscopy. The optical absorbance data showed an increase of absorbance in contrast with PPy and SnO₂. There was a red shift in absorbance wavelengths and a decrease in band gaps for the prepared PV structures. To investigate the electrical properties of the obtained structures, current-voltage characteristic was measured. The best structure showed an open-circuit voltage of 0.170?V, a short-circuit current density of 0.017?mA/cm², a fill factor of 0.36 and power conversion efficiency of 0.076.     

The adoption and mechanism of KIO4 for redox-equilibrated stabilization of FeO4 2− as an equalizer in water

The inherent thermodynamic instability of FeO₄ ²⁻ in water restricts its applications in water treatment, battery, and organic synthesis. The objective of this paper was to research and develop an additive for stabilization and mechanism of aqueous FeO₄ ²⁻ solution on the basis of a choice of the redox equilibration. In this study, it was found that FeO₄ ²⁻ in water was stabilized by the right match and adoption of KIO₄ called an equalizer. The redox thermodynamic analysis and dynamic experimental results show that the adoption of KIO₄ equalizer greatly increased lifetime of FeO₄ ²⁻ in water by orders of magnitude. The stabilization mechanism is attributed to occur via the effect of redox equilibrium of the FeO₄ ²⁻ and the IO₄ ⁻ species, as well as the formation of an oxidizing chemical environment. This study opens up possibilities for stabilization of solid ferrate compounds, for example, for use in the water treatment and super-iron battery.

     

AgF desalination procedure for the routine determination of oxygen and hydrogen isotopic composition of saline waters and brines

The routine methods for stable oxygen and hydrogen isotope analysis of water involve water–CO₂ gas equilibration and water reduction on hot metal (e.g. Zn, Cr, U) and subsequent mass spectrometric analysis of the evolved gases of CO₂ and H₂ for ¹⁸O/¹⁶O and ²H/¹H ratios, respectively. Precise determination of the isotopic composition of water in brines with application of these standard methods is still problematic and technically often impossible due to detrimental influence of dissolved salts. The new method of brine desalination presented in this study overcomes the problem of the isotope salt effects encountered during the application of the routine techniques for the determination of the isotopic composition of high saline waters. The procedure combines two technical steps: (i) the chemical precipitation of Mg and Ca ions as insoluble non-hydroscopic fluorides, and (ii) the vacuum distillation of water from solution–precipitate mixture. The application of simple vacuum distillation allows full extraction of water and dehydration of remaining salts in a temperature range from 300 to 350?°C without hydrogen and oxygen isotope fractionation. The precision and accuracy of δ¹⁸O and δ²H determination of saline waters and brines with prior application of AgF desalination procedure is comparable with that usually obtained for fresh waters.     

Photophysical studies of xanthene dye in alkanols and in presence of inorganic ions

Eosin Y belongs to a xanthene group. It is an anionic fluorescent dye. The absorbance and fluorescence of Eosin Y have been investigated in a series of alkanols (methanol to propanol). When the solvents are added to the aqueous solution of Eosin Y (EY) the absorbance and fluorescence intensity are enhanced. The alkanols are found to affect the absorption and fluorescence spectra of the dye. On the basis of solvent adsorption model the binding constants of the dye with alkanols have been estimated. The interaction of solvent molecule with dye in aqueous solution is specific in nature. The fluorescence quenching of Eosin Y by the inorganic ions [Fe(CN)₆]⁻³, [Fe(CN)₆]⁻⁴ and Cl⁻ was also observed. The ions influenced the quenching process to different extents. The rate constants of quenching were calculated using the Stern-Volmer equation. The equilibrium constant of dye in presence of inorganic ions are determined by Scott equation.     

The effect of internal Co2 conductance on leaf carbon isotope ratio

We estimated internal CO₂ conductance (g_i ) for C₃ plant species of different life forms (annual herbs, deciduous trees and evergreen trees) grown in a variety of environments to examine the effect of g i on their leaf carbon isotope ratio (i¹³C). The purpose of this study was to test the validity of using i¹³C as an index of photosynthetic water use efficiency (WUE). When comparing deciduous tree species grown in contrasting light environments, there was a strong positive relationship between i¹³C and WUE. Similarly, i¹³C was positively correlated to WUE when comparing the different species of evergreen trees. However, the difference in WUE between evergreen and deciduous tree species did not relate to that in leaf i¹³C. In addition, WUE was similar between highland and lowland herbaceous plants, although the former had a much higher i¹³C. The positive relationship between i¹³C and WUE did not hold across different life forms and different altitudes when differences in g_i did not relate to those in stomatal conductance, resulting in independence of chloroplast CO₂ partial pressure from intercellular CO₂ partial pressure.     

LiFePO<Subscript>4</Subscript>/C with high capacity synthesized by carbothermal reduction method

The olivine-type LiFePO₄/C cathode materials were prepared via carbothermal reduction method using cheap Fe₂O₃ as raw material and different contents of glucose as the reducing agent and carbon source. Their structural and morphological properties were investigated by X-ray diffraction, scanning electron microscope, transmission electron microscope, and particle size distribution analysis. The results demonstrated that when the content of the carbon precursor of glucose was 16 wt.%, the synthesized powder had good crystalline and exhibited homogeneous and narrow particle size distribution. Even and thin coating carbon film was formed on the surface of LiFePO₄ particles during the pyrolysis of glucose, resulting in the enhancement of the electronic conductivity. Electrochemical tests showed that the discharge capacity first increased and then decreased with the increase of glucose content. The optimal sample synthesized using 16 wt.% glucose as carbon source exhibited the highest discharge capacity of 142 mAh g⁻¹ at 0.1C rate with the capacity retention rate of 90.4% and 118 mAh g⁻¹ at 0.5C rate.     

Behaviour of the resonant absorption area of a57Fe-doped Ni/C catalyst during sulfidation

In-situ Mössbauer spectroscopy measurements down to 4.2 K were performed on a⁵⁷Fe:Ni(0.5)/C catalyst after various successive sulfidation treatments. After exposure of the catalysts to the H₂S/H₂ gas mixture at room temperature, part of the⁵⁷Fe becomes sulfidic. The rest is present as a sulfate-like intermediate species. The interaction between this intermediate species and the carbon support material is influenced by water. At temperatures below 180 K the water is rigid, at higher temperatures the water becomes mobile. This weakens the interaction with the support material, resulting in a decrease of the RAA. The interaction between the sulfidic species and the support material is not influenced by water. However, this species is not yet very well ordered; therefore, the⁵⁷Fe is loosely bound. The ordering becomes better by sulfidation at higher temperatures, leading to an increase of the RAA.