Spontaneous reductive decomposition behavior of hydrogen permanganate in water for chemical decontamination of nuclear power plants

The spontaneous reductive decomposition behavior of HMnO₄ in water as a function of the initial HMnO₄ concentration and reaction temperature was investigated. The decomposition of HMnO₄ was fast in the early stage of the reaction and thereafter slowed down significantly, regardless of the initial HMnO₄ concentration. The loss of HMnO₄ by spontaneous reductive decomposition increased with increasing reaction temperature. Based on the experimental results and the classical nucleation theory, a mathematical model was developed using a combination of two first-order reactions representing the nucleation and crystal growth of MnO₂ to predict the spontaneous reductive decomposition behavior of HMnO₄.     

Silylation of sodium silicate-based silica aerogel using trimethylethoxysilane as alternative surface modification agent

Trimethylethoxysilane (TMES) has been recognized as a good co-precursor to increase the degree of hydrophobicity during the synthesis of a silica aerogel because of its methyl groups. Therefore, some physical properties of silica aerogels, including the contact angle and porosity, were investigated using TMES as a co-precursor at different molar ratios with the main precursor such as tetramethoxysilane (TMOS) or tetraethoxysilane (TEOS). In contrast to TMES, most silylating agents such as hexamethyldisilazane (HMDZ) and trimethylchlorosilane (TMCS) have been used for surface modification because of their ability to enhance the hydrophobicity of the aerogel surface. This work examines the silylation effect, which includes increasing hydrophobicity by TMES to determine the possibility of using it as an alternative silylating agent during ambient pressure drying in the synthesis of sodium silicate-based silica aerogel. In addition, the physical properties of sodium silicate-based silica aerogels with silylation under different TMES/TMCS volume ratio are investigated. The physical properties of sodium silicate-based aerogels can be changed by the TMES/TMCS volume ratio during the surface modification step. Aerogels with a high specific surface area (458?m²/g), pore volume (3.215?cm³/g), porosity (92.7%), and contact angle (131.8°) can be obtained TMES/TMCS volume ratio of 40/60.

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Coumaraz‐2‐on‐4‐ylidene: Ambiphilic N‐Heterocyclic Carbenes with a Tunable Electronic Structure

Herein, a coumaraz‐2‐on‐4‐ylidene ( 1 ) as a new example of an ambiphilic N‐heterocyclic carbene, having electronic properties that can be fine‐tuned, is reported. The N‐carbamic and aryl groups on the carbene carbon center provide exceptionally high electrophilicity and nucleophilicity simultaneously to the carbene center, as evidenced by the ⁷⁷Se NMR chemical shifts of their selenoketone derivatives and the CO stretching strengths of their rhodium carbonyl complexes. Since the precursors of 1 could be synthesized from various functionalized Schiff bases in a practical and scalable manner, the electronic properties of 1 can be fine‐tuned in a quantitative and predictable way by using the Hammett σ constant of the functional groups on aryl ring. The facile electronic tuning capability of 1 may be applicable to eliciting novel properties in main‐group and transition‐metal chemistry.     

采用金属有机骨架材料M(HBTC)(4,4'-bipy)·3DMF(M=Ni,Co,Zn)催化CO_2与环氧丙烷的环加成反应（英文）

采用溶剂热法合成了三种M(HBTC)(4,4’-bipy)·3DMF(M=Ni,Co,Zn,HBTC=1,3,5-均苯三甲酸,4,4’-bipy=4,4′-联吡啶)结构的支柱层金属有机骨架材料(MOFs).首次采用溶剂热和微波法合成了Zn(HBTC)(4,4’-bipy)·3DMF,并采用多种物理化学方法对其进行了表征.M(HBTC)(4,4’-bipy)·3DMF中包含有M2+离子的蜂窝网格层和BTC单元,BTC单元与4,4’-联吡啶柱进一步交联形成三维多孔骨架材料.在采用烷基铵卤化物作为助催化剂和无溶剂的条件下,所有MOFs材料均对催化固定CO_2与环氧化合物环加成制备环状碳酸酯反应表现出非常好的协同催化性能,其催化活性高低顺序为:ZnCoNi,这可通过酸-碱双功能特性进行解释.采用微波法合成的Zn(HBTC)(4,4’-bipy)·3DMF材料表现出与常规催化剂相似的物理化学性质和催化性能.考察了不同制备参数的影响和材料的重复使用性能,并提出了该反应的可能机理     

Mass Spectral Detection of Forward- and Reverse-Hydrogen/Deuterium Exchange Resulting from Residual Solvent Vapors in Electrospray Sources

Characterizing glycans is analytically challenging since glycans are heterogeneous, branched polymers with different three-dimensional conformations. Hydrogen/deuterium exchange-mass spectrometry (HDX-MS) has been used to analyze native conformations and dynamics of biomolecules by measuring the mass increase of analytes as labile protons are replaced with deuterium following exposure to deuterated solvents. The rate of exchange is dependent on the chemical functional group, the presence of hydrogen bonds, pH, temperature, charge, and solvent accessibility. HDX-MS of carbohydrates is challenging due to the rapid exchange rate of hydroxyls. Here, we describe an observed HDX reaction associated with residual solvent vapors saturating electrospray sources. When undeuterated melezitose was infused after infusing D₂O, samples with up to 73% deuterium exchange were detected. This residual solvent HDX was observed for both carbohydrates and peptides in multiple instruments and dependent on sample infusion rate, infusion time, and deuterium content of the solvent. This residual solvent HDX was observed over several minutes of sample analysis and persisted long enough to alter the measured deuterium labeling and possibly change the interpretation of the results. This work illustrates that residual solvent HDX competes with in-solution HDX for rapidly exchanging functional groups. Thus, we propose conditions to minimize this effect, specifically for top-down, in-electrospray ionization, and quench-flow HDX experiments.

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Synthesis and evaluation of triphenylphosphonium conjugated 18F-labeled silica nanoparticles for PET imaging

Journal of Radioanalytical and Nuclear Chemistry - Accumulation of triphenylphosphonium (TPP) is normally observed in the mitochondria from the extracellular spaces due to the high difference in...     

Uranium recovery with zinc distillation from a liquid zinc cathode for pyroprocessing

Journal of Radioanalytical and Nuclear Chemistry - U recovery test was performed on a Zn-U alloy to confirm the feasibility of Zn as an alternative cathode material. An evaporation test of pure Zn...     

Applicability of in situ detectors for radiological assessment of strontium-90 in rivers and lakes

Journal of Radioanalytical and Nuclear Chemistry - An in situ detector for radiological assessments of strontium-90 (90Sr) in river and lake water is developed, based on a CaF2(Eu) scintillator,...     

Synthesis of water soluble metalloporphyrin-cored amphiphilic star block copolymer photocatalysts for an environmental application

Two series of water-soluble metalloporphyrin-cored amphiphilic star block copolymers were synthesized by controlled radical polymerizations such as atom transfer radical polymerization (ATRP) and reversible addition fragmentation chain transfer (RAFT), which gave eight amphiphilic block copolymer arm chains consisting of poly(n-butyl acrylate-b-poly(ethylene glycol) methyl ether methacylate) (PnBA-b-PEGMEMA, M_n,GPC = 78,000, M_w/M_n = 1.2, 70 wt% of PPEGMEMA) and poly(styrene-b-2-dimethylamino ethyl acrylate) (PS-b-PDMAEA, M_n,GPC = 83,000, M_w/M_n = 1.2, 67 wt% of PDMAEA), yielding porphyrin(Pd)-(PnBA-b-PPEGMEMA)₈ and porphyrin(Pd)-(PS-b-PDMAEA)₈, respectively. Obtained metalloporphyrin polymer photocatalysts were homogeneously solubilized in water to apply to the removal of chlorophenols in water, and was distinguished from conventional water-insoluble small molecular metalloporphyrin photocatalysts. Notably, we found that the water-soluble star block copolymers with hydrophobic–hydrophilic core–shell structures more effectively decomposed the chlorophenol, 2,4,6-trichlorophenol (2,4,6-TCP), in water under visible light irradiation (k = 1.39 h^?1, t_1/2 = 0.5 h) in comparison to the corresponding water-soluble star homopolymer, because the hydrophobic core near the metalloporphyrin effectively captured and decomposed the hydrophobic chlorophenols in water.     

Highly efficient mesoporous WO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>/KIT-6 catalysts for oxidative desulfurization of dibenzothiophene with hydrogen peroxide

Oxidative desulfurization (ODS) of organic compounds containing sulfur element from a model oil was performed using tungsten oxide catalysts supported on mesoporous silica with cubic Ia3d mesostructure, well-defined mesopores (7.2 nm), high surface area (719 m²/g), and three-dimensional pore network (WO _x /KIT-6). The prepared WO _x /KIT-6 catalysts (5–20 wt% WO _x ) were characterized by X-ray diffraction analysis, N₂ sorption measurements, electron microscopy, H₂-temperature programmed reduction, Raman spectroscopy, and thermogravimetric analysis. Among the mesoporous catalysts, 10 wt% WO _x /KIT-6 exhibited the best catalytic performance. Sulfur-containing organic compounds, such as dibenzothiophene, 4,6-dimethyldibenzothiophene, and benzothiophene, were completely (100 %) removed from the model oil over 10 wt% WO _x /KIT-6 catalyst in 2 h. In addition, the catalyst could be reused several times with only slight decrease in catalytic activity.