Photonic crystal sensor for organophosphate nerve agents utilizing the organophosphorus hydrolase enzyme

We developed an intelligent polymerized crystalline colloidal array (IPCCA) photonic crystal sensing material which reversibly senses the organophosphate compound methyl paraoxon at micromolar concentrations in aqueous solutions. A periodic array of colloidal particles is embedded in a poly-2-hydroxyethylacrylate hydrogel. The particle lattice spacing is such that the array Bragg-diffracts visible light. We utilize a bimodular sensing approach in which the enzyme organophosphorus hydrolase (OPH) catalyzes the hydrolysis of methyl paraoxon at basic pH, producing p-nitrophenolate, dimethylphosphate, and two protons. The protons lower the pH and create a steady-state pH gradient. Protonation of the phenolates attached to the hydrogel makes the free energy of mixing of the hydrogel less favorable, which causes the hydrogel to shrink. The IPCCA’s lattice constant decreases, which blueshifts the diffracted light. The magnitude of the steady-state diffraction blueshift is proportional to the concentration of methyl paraoxon. The current detection limit is 0.2 μmol methyl paraoxon per liter.     

Sensitive and Selective Spectrophotometric Determination of Para- and Ortho- Aminophenol with Hypochlorite-Alkaline Phenol (Berthelot) Reagents

Abstract

A highly selective and sensitive method is described for the determination of para- as well as ortho-isomers of aminophenol. The method involves oxidative coupling of aminophenol with Berthelot hypochlorite-alkaline phenol reagents. The reaction yielded a blue chromophose with p-aminophenol (∑=10,000 at 633 nm) and a dark green chromophore with o-aminophenol (∑=1436 at 845 nm). The reaction mechanisms involved in the chromophore formation are discussed.     

Die Ammonolyse von (NH4)2GeF6. Darstellung und Struktur von NH4[Ge(NH3)F5]

Ammonolysis Reaction of (NH₄)₂GeF₆. Synthesis and Structure of NH₄[Ge(NH₃)F₅] (NH₄)₂GeF₆ reacts with ammonia to yield NH₄[Ge(NH₃)F₅] at 280°C. The reaction path was elucidated by in situ time and temperature resolved X-ray powder diffraction. NH₄[Ge(NH₃)F₅] crystallizes isostructurally to NH₄[Si(NH₃)F₅] in the tetragonal space group P4/n (No. 85) with lattice constants a = 619.41(1) pm and c = 724.70(1) pm. The germanium atom is coordinated by five fluorine atoms and the nitrogen atom of the ammonia molecule. The ammonium cation is located on the Wyckoff position (2 a) in P4/n. The crystal structure is stabilized by extensive hydrogen bonding.     

Modeling of stimulated hydrogel volume changes in photonic crystal Pb2+ sensing materials

We modeled the stimulated hydrogel volume transitions of a material which binds Pb2+ and is used as a photonic crystal chemical sensing material. This material consists of a polymerized crystalline colloidal array (PCCA) hydrogel which contains a crown ether molecular recognition group. The PCCA is a polyacrylamide hydrogel which embeds a crystalline colloidal array (CCA) of monodisperse polystyrene spheres of approximately 100 nm. The array spacing is set to diffract light in the visible spectral region. Changes in the hydrogel volume induced by Pb2+ binding alter the array spacing and shift the diffracted wavelength. This system allows us to sensitively follow the hydrogel swelling behavior which results from the immobilization of the Pb2+ by the crown ether chelating groups. Binding of the Pb2+ immobilizes its counterions. This results in a Donnan potential, which results in an osmotic pressure which swells the hydrogel. We continue here our development of a predictive model for hydrogel swelling based on Flory's theory of gel swelling. We are qualitatively able to model the PCCA swelling but cannot correctly model the large responsivity observed at the lowest Pb2+ concentrations which give rise to the experimentally observed low detection limits for Pb2+. These PCCA materials enable stimulated hydrogel volume transitions to be studied.     

Reactivity of ytterbium in liquid ammonia

A solution of metallic ytterbium in liquid ammonia reacts readily with various carbonyl complexes of metals to form the corresponding lanthanide carbonylmetallates. The reaction of an excess of Yb in liquid NH₃ with [CpFe(CO)₂]₂ gave (THF)₄Yb[Fe(CO)₂Cp]₂ in 42% yield. It was suggested that the resulting complex contains two equivalent Yb−Fe bonds. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1883–1885, October, 1997.     

杂化钙钛矿(NH3C6H12NH3)CuCl4的制备与表征

采用低温溶液法合成了含有二铵阳离子结构的新型二维层状结构的有机/无机杂化钙钛矿材料（NH₃C₆H₁₂NH₃） CuCl₄。采用元素分析、红外光谱、X射线衍射和紫外-可见光吸收光谱等手段对其结构与性能进行了表征。结果表明该材料的紫外-可见吸收光谱吸收峰位于285 nm和387 nm,层间距为1.18 nm。二铵阳离子的引入,使有机层⁺NH₃C₆H₁₂NH₃+与2个相邻的无机框架CuCl₄^2-分别通过较强的氢键结合在一起,排列更为规整,热稳定性更高。与单铵阳离子结构的杂化钙钛矿材料相比,由于不存在两层有机分子层间较弱的范德华力,（NH₃C₆H₁₂NH₃） CuCl₄材料的电阻率为1.36×10⁵ Ω·cm,比单胺结构的杂化钙钛矿材料的电阻率低3个数量级。     

Colloidal Synthesis of CH3NH3PbBr3 Nanoplatelets with Polarized Emission through Self‐Organization

We report a combined experimental and theoretical study of the synthesis of CH₃NH₃PbBr₃ nanoplatelets through self‐organization. Shape transformation from spherical nanodots to square or rectangular nanoplatelets can be achieved by keeping the preformed colloidal nanocrystals at a high concentration (3.5 mg mL⁻¹) for 3 days, or combining the synthesis of nanodots with self‐organization. The average thickness of the resulting CH₃NH₃PbBr₃ nanoplatelets is similar to the size of the original nanoparticles, and we also noticed several nanoplatelets with circular or square holes, suggesting that the shape transformation experienced a self‐organization process through dipole–dipole interactions along with a realignment of dipolar vectors. Additionally, the CH₃NH₃PbBr₃ nanoplatelets exhibit excellent polarized emissions for stretched CH₃NH₃PbBr₃ nanoplatelets embedded in a polymer composite film, showing advantageous photoluminescence properties for display backlights.     

Reactivity of some sulphur- and non-sulphur-containing amino acids towards water soluble colloidal MnO<Subscript>2</Subscript>. A kinetic study

Kinetic data for the oxidation of glutathione (reduced, GSH), cysteine, glycine and glutamic acid by colloidal manganese dioxide, (MnO₂) _n are reported. Colloidal MnO₂, oxidized glutathione to disulphide (glutathione, oxidized), was reduced to manganese (II). Glycine and glutamic acid (structural units of glutathione) are not oxidized by colloidal MnO₂, but the other structural unit, cysteine, is also oxidized by the same oxidant under similar experimental conditions. This is interpreted in terms of the rate-determining colloidal MnO₂-S bonded intermediate. The reactivity of GSH towards colloidal MnO₂ is very much higher than cysteine. Kinetics of oxidation of GSH and cysteine by colloidal MnO₂ were performed spectrophotometrically as a function of [GSH], [cysteine], colloidal [(MnO₂) _n ], [HClO₄], temperature and trapping agents sodium fluoride and manganese (II) (reduction product of colloidal MnO₂). The purpose of this work was to study the role of –NH₂, –COOH, –SH groups present in the carbon chain of the above amino acids. It was found that the reactivity of –SH group is higher than –NH₂ and –COOH groups. The mechanisms, involving a colloidal MnO₂ complex with GSH and cysteine, are proposed. The complexes decompose in a rate-determining step, leading to the formation of free radical and manganese (III), which is also an intermediate. The dimerization of radicals takes place in a subsequent fast step to yield the products.     

Crystal Structure and EPR Spectra of cis—Dioxo—molybdenum（V） Complex with o—Aminophenol

ＩｎｔｒｏｄｕｃｔｉｏｎＭｏｌｙｂｄｅｎｕｍｉｓｗｉｄｅｌｙｕｓｅｄｉｎｂｉｏｌｏｇｉｃａｌｓｙｓｔｅｍｓｄｕｅｔｏｔｈｅｔｗｏｂａｓｉｃｆｏｒｍｓ :ｎｉｔｒｏｇｅｎａｓｅｓａｎｄｏｘｏｔｒａｎｓｆｅｒａｓｅｓｏｒｏｘｏｍｏｌｙｂｄｏｅｎｚｙｍｅｓ .Ｔｈｅｌａｔｔｅｒａｓｔｈｅｍｏｎｏｎｕｃｌｅａｒａｃｔｉｖｅｓｉｔｅｓｏｆａｍｕｃｈｍｏｒｅｄｉｖｅｒｓｅｇｒｏｕｐｏｆｅｎｚｙｍｅｓｉｎｇｅｎｅｒａｌｆｕｎｃｔｉｏｎｃａｔａｌｙｔｉｃａｌｌｙｔｒａｎｓｆｅｒａｎｏｘｙｇｅｎａｔｏｍｅｉｔｈｅｒｔ…     

Complex Nonlinear Behavior in the Bromate–2‐Aminophenol Reaction

The bromate–2‐aminophenol reaction in a batch reactor was investigated in this research, in which both simple and sequential oscillations were observed. The occurrence of sequential oscillations were found to be very sensitive to changes of the initial concentrations, where decreasing the concentration of sulfuric acid or sodium bromate or increasing the 2‐aminophenol concentration caused the two oscillation windows to coalesce. Lowering the reaction temperature from 30 to 5°C also caused the two oscillation windows to merge into one. A phase diagram in the bromate–sulfuric acid concentration plane demonstrates that sequential oscillations only occur within a narrow band of conditions. Mechanistic studies of the system through employing ¹H NMR and mass spectrometry suggest that a dibrominated ortho‐benzoquinone is a major product. The oxidation of 2‐aminophenol, on the other hand, can lead to the formation of pyrocatechol, which may be the substrate responsible for the second set of oscillations.     

PO43-掺杂和AlF3包覆协同增强Li1.2Ni0.13Co0.13Mn0.54O2正极材料电化学性能

本研究采用PO₄^3-掺杂和AlF₃包覆的协同改性策略制备了P-LNCM@AlF₃正极材料(P=PO₄^3-,LNCM=Li_1.2Ni_0.13Co_0.13Mn_0.54O₂),提高了LNCM的结构稳定性以及抑制了界面副反应。其中,大四面体的PO₄^3-聚阴离子掺杂在晶格中抑制了过渡金属离子的迁移,降低体积变化,从而稳定了晶体结构,而且PO₄^3-掺杂能够扩大锂层间距,促进Li⁺的扩散,从而提升材料的倍率性能。此外,AlF₃包覆层能抑制材料与电解液的副反应从而提升界面稳定性。基于以上优势,P-LNCM@AlF₃正极表现出了优异的电化学性能。在1C电流密度下表现出了179.2 mAh·g^-1     

Novel amphoteric pH-sensitive hydrogels derived from ethylenediaminetetraacetic dianhydride, butanediamine and amino-terminated poly(ethylene glycol): Design, synthesis and swelling behavior

Novel amphoteric pH-sensitive hydrogels with pendant carboxyl and backbone tertiary amine groups were designed and synthesized. First, ethylenediaminetetraacetic dianhydride (EDTAD) reacted with butanediamine (BDA) via N-acylation reaction to give a polyamide prepolymer with pendant carboxyl groups (PEB–COOH); then amino-terminated poly(ethylene glycol) 500 (ATPEG500) was added as a cross-linking agent to produce the desired network polymer (PEB–ATPEG500–COOH). The obtained hydrogels are potentially degradable and non-toxic since its backbone and cross-linking sections are both linked by amide bonds and all monomers have been proved as safe. FTIR, ¹H NMR, ¹³C NMR and ninhydrin reaction method were employed to qualitatively and quantitatively characterize the obtained polymers. The effect of cross-linking agent amount, characterized by the molar ratios (R_m) of NH₂ groups in ATPEG500 to pendant COOH groups in PEB–COOH, on the swelling behavior of the proposed hydrogel was examined. The results indicate that the equilibrium swelling ratio decreases and the pH-sensitivity becomes retarded with the increase of R_m. For PEB–ATPEG500–COOH hydrogels with R_m no more than 0.42, they exhibited three SR_e variation zones at pH 2–4, pH 6–7 and pH 9–11, respectively, suggesting obvious and interesting amphoteric pH-sensitivity. In addition, the swelling kinetics tests on PEB–ATPEG500–COOH with R_m = 0.32 reveal that the swelling kinetics of proposed hydrogel follows a Fickian diffusion process in media of pH 7, and an anomalous diffusion process in media of pH 2 and 11. The above obtained results will facilitate the application of this proposed hydrogel in biomedical fields, particularly in the drug controlled release.     

Synthesis, characterization and thermal decomposition of thiourea complexes of antimony and bismuth triiodide

The thiourea complexes of antimony and bismuth triiodide were synthesized by a direct reaction of antimony and bismuth triiodide with thiourea powder at room temperature. The formula of the complex is MI₃[SC(NH₂)₂]₃(M=Sb, Bi). The crystal structure of the complexes belongs to monoclinic system and the lattice parameters are a=1.4772 nm, b=1.6582 nm, c=2.0674 nm and β=90.81° for SbI₃(SC(NH₂)₂)₃ and a=1.4009 nm, b=2.0170 nm, c=2.0397 nm and β=90.84° for BiI₃[SC(NH₂)₂]₃. The infrared spectra reveal that the trivalent antimony or bismuth ion is coordinated by the nitrogen atom, not the sulfur atom of the thiourea. Thermal analysis shows that there are two times structure rearrangements or phase transformation in the complexes from 100 to 170°C.     

Determination of the dissociation kinetics of a transient intermediate

Tandem mass spectrometry provides information on the dissociation pathways of gas-phase ions by providing a link between product ions and parent ions. However, there exists a distinct possibility that a parent ion does not dissociate directly to the observed product ion, but that the reaction proceeds through unobserved reaction intermediates. This work describes the discovery and kinetic analysis of an unobserved reaction intermediate with a quadrupole ion trap. [a ₄−NH₃] ions formed from [YGβFL+H] ions dissociate to [(F*YG−NH₃)−CO] ions. It is expected, however, from previous results, that [F*YG−NH₃] ions should form prior to [(F*YG−NH₃)−CO] ions. Double-resonance experiments are used to demonstrate the existence of intermediate [F*YG − NH₃] ions. Various kinetic analyses are then performed using traditional collision-induced dissociation kinetics and double-resonance experiments. The phenomenological rates of formation and decay of peptide rearrangement ion dissociation products are determined by curve fitting decay and formation data generated with the kinetics experiments. The data generated predict an observable level of the intermediate in a time frame accessible but previously not monitored. By examining early product-ion formation, the intermediate ions, [F*YG−NH₃]⁺, are observed.     

Diffuse reflectance infrared Fourier transform spectral study of the interaction of 3-aminopropyltriethoxysilane on silica gel. Behavior of amino groups on the surface

 Three silica gel sample systems, modified with 3-amino-propyltriethoxysilane (APTS), were prepared by sequentially sampling the reaction mixture at various time intervals, and the diffuse reflectance infrared Fourier transform (DRIFT) spectra of these samples were measured in the regions 2700–3500 and 1300–2000 cm^-1. The IR bands observed at 1597 and 1629–1633 cm^-1 were assigned to the deformation modes of NH₂ and NH⁺ ₃ groups, respectively. The intensities of these two bands are dependent on both the APTS concentration used in the preparation and the reaction time. The results are summarized as fol-lows. For the sample systems in which smaller APTS concentration were used, most of the NH₂ groups of the aminopropyl segments are converted into the NH⁺ ₃ groups on the surface, showing that the SiO^-…H⁺NH₂-type structure is predominantly stabilized on the surface of the silica gel. As the APTS concentration in the reaction mixture increases, the population of NH₂ groups in the silane layer coated onto the surface increases. Interpretation of the CH stretch region further suggests that cyclic structures may be formed on the surface as a consequence of the formation of NH⁺ ₃ groups. Received: 18 November 1996 Accepted: 14 February 1997     

Kinetic study of Berthelot reaction steps in the absence and presence of coupling reagents

Several reaction steps in the Berthelot reaction for the determination of ammonia have been separately studied. A reaction order of two has been confirmed for the reaction between HOCl and NH(3). The rate constant for this reaction has been determined to be 3.2 x 10(6)l.mole(-1).sec(-1). The first evidence for the formation of benzoquinonechlorimine is presented. Pentacyanoferrate coupling reagents which accelerate the production of indophenol have been found to operate on the reaction between NH(2)Cl and phenol. The rate constant for the final step of the reaction sequence has been determined to be 5.3 x 10(-3)l.mole(-1).sec(-1). A reaction between chlorimine and pentacyanoferrate compounds has been found to be responsible for the formation of a green product in the presence of excess of coupling reagent.     

Rapid preparation of uniform colloidal indium hydroxide by the controlled double-jet precipitation

The synthesis of uniform colloidal rod-like In(OH)₃ particles from relatively concentrated solutions of InCl₃ (0.1 mol dm^-3) in short reaction time (<15 min) by the controlled double-jet precipitation (CDJP) technique is described. The effects of the molar ratio of [NH₄OH]/[InCl₃], temperature, concentration of the reactants, and reaction time on the size and shape of the final products are investigated. It is found that such In(OH)₃ particles are formed by aggregation of nanosize subunits. Received: 14 April 1998 Accepted: 15 April 1998     

PO43-掺杂和AlF3包覆协同增强Li1.2Ni0.13Co0.13Mn0.54O2正极材料电化学性能

本研究采用PO₄^3-掺杂和AlF₃包覆的协同改性策略制备了P-LNCM@AlF₃正极材料(P=PO₄^3- ,LNCM=Li_1.2Ni_0.13Co_0.13Mn_0.54O₂),提高了LNCM的结构稳定性以及抑制了界面副反应。其中,大四面体的PO₄^3-聚阴离子掺杂在晶格中抑制了过渡金属离子的迁移,降低体积变化,从而稳定了晶体结构,而且PO₄^3-掺杂能够扩大锂层间距,促进Li⁺的扩散,从而提升材料的倍率性能。此外,AlF₃包覆层能抑制材料与电解液的副反应从而提升界面稳定性。基于以上优势,P-LNCM@AlF₃正极表现出了优异的电化学性能。在1C电流密度下表现出了179.2 mAh·g^-1的放电比容量,循环200圈后仍有161.5 mAh·g^-1的放电比容量,容量保持率可达90.12%。即使在5C的高电流密度下仍可提供128.8 mAh·g^-1的放电比容量。     

Thermogravimetric Investigations During the Synthesis of Silica-based MCM-41

MCM-41 material was synthesized starting from hydrogel containing colloidal fumed silica, sodium silicate, cetyltetramethylammonium bromide(CTMABr) as surfactant, and distilled water as solvent. These reactants were mixed to obtain a gel with the following composition: 4SiO₂:1Na₂O:1CTMABr:200H₂O. The hydrogel with pH=14 was hydrothermally treated at100°C, for 4 days. Each day, the pH was measured, and then adjusted to 9.5–10 by using 30%acetic acid solution. Thermogravimetry was the main technique, which was used to monitor the participation of the surfactant on the MCM-41 nanophase, being possible to determine the temperature ranges relative to water desorption as well as the surfactant decomposition and silanol condensation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Heteronukleare Komplexverbindungen mit Metall—Metall-Bindungen. IX [1]. Amin-kupfer(I)-carbonylmetallate mit Cobalt,Eisen oder Mangan

Heteronuclear Coordination Compounds with Metal—Metal Bonds. IX. Amine Copper(I) Carbonyl Metalates with Cobalt, Iron, or Manganese Colourless crystals of the carbonyl copper complex [(NH₃)₃(CO)Cu][Co(CO)₄] ( 1 a ) are formed in the reaction of [Cu(NH₃)₄]Cl and Na[Co(CO)₄] (T < ? 8°C, p_CO = 1 bar); above ?5°C and under N₂-atmosphere 1 a converts to [(NH₃)₂CuCo(CO)₄] ( C ), which serves as a starting material for the synthesis of new copper cobaltates: the amines N-amino piperidine, N,N-dimethyl ethylenediamine (dmed) and N-benzyl N,N′-dimethyl ethylenediamine (bn-dmed) replace NH₃ to form [(C₅H₁₀N? NH₂)₃CuCo(CO)₄] ( 1 b ), [(dmed)CuCo(CO)₄] ( 1 c ), [(bn-dmed)CuCo(CO)₄] ( 1 d ) the Cu? Co-bond remaining intact. [(NH₃)₂CuFe(CO)₃NO] ( 2 a ) is isosteric with C ; it is synthesized from [Cu(NH₃)₄]Cl and Na[Fe(CO)₃NO] in aqueous solution; 2 a reacts with N,N,N′,N′-tetramethyl ethylenediamine (tmed) to form [(tmed)(NH₃)CuFe(CO)₃NO] ( 2b ). The [Mn(CO)₅]^? ion reacts with ammine copper ions to form the tetranuclear cluster [{(NH₃)CuMn(CO)₅}₂] ( 3 ). All new compounds have been investigated by X-ray structure analysis.