Synthesis and characterization of UV-curable polydimethylsiloxane epoxy acrylate

UV-curable polydimethylsiloxane epoxy acrylate (PSEA) was synthesized by hydrosilylation of allyl glycidyl ether with hydrogen-containing polydimethylsiloxane to give polydimethylsiloxane-type epoxy resin which modified with acrylic acid. The curing speed and the double bond conversion in the UV cured film were influenced by the purity of PSEA with Fourier transform infrared spectroscopy (FT-IR) measurements. The influences of the synthetic process, such as, the reaction temperature, the concentration of reactants and the catalyst which determined the purity and activity of resins were discussed in detail. The structures of this resin were characterized by ¹H-NMR and FT-IR spectra. The molecular weight was checked by gel permeation chromatography, and M_n is 45,000. The properties of the cured film were also investigated by thermogravimetric analyzer, dynamical thermal mechanical analysis, and etc. For example, tensile strength (6.9 Mpa), elongation (20%), hardness (A; 18), water absorption (24 h; 2%), weight loss (40 min, 300 °C; 5%) and etc.     

Determination of adrenaline by using inhibited Ru(bpy)3 electrochemiluminescence

Adrenaline was found to inhibit strongly the electrochemiluminescence (ECL) from the Ru(bpy)₃²⁺/tripropylamine system when a working Pt electrode was maintained at 1.05 V (versus Ag/AgCl) in pH 8.0 phosphate buffer. On this basis, a flow injection (FI) procedure with inhibited electrochemiluminescence detection has been developed for determination of adrenaline. The method exhibited a good reproducibility, sensitivity, and stability with a detection limit (signal-to-noise ratio = 3) of 7.0×10⁻⁹ mol l⁻¹ and dynamic concentration range of 2×10⁻⁸ to 1×10⁻⁴ mol l⁻¹. The relative standard deviation was 2.2% for 1.0×10⁻⁶ mol l⁻¹ adrenaline (n=11). The method was successfully applied to the determination of adrenaline in pharmaceutical samples. Moreover, ECL emission spectra, UV-Vis absorption spectra and cyclic voltammograms of Ru(bpy)₃²⁺/tripropylamine/adrenaline were studied. The inhibition mechanism has been proposed as the interaction of electrogenerated Ru(bpy)₃^2+* and the o-benzoquinone derivatives, adrenochrome and adrenalinequinone, at the electrode surface.     

On the interaction of solitons for a class of integrable systems in the spacetime R n+1

A class of integrable systems of nonlinear partial differential equations in the spacetime R ⁿ⁺¹ is introduced. Single and multi-soliton solutions are constructed by using the Darboux matrix method. It is proved that as t±, a k multi-soluton solution splits asymptotically into k single solitons. Moreover, the interaction between solitons is elastic if we consider their magnitudes only.The work is C. H. Gu supported by the Chinese National Program for fundamental research nonlinear science.     

Growth of Sb(2)E(3) (E = S, Se) polygonal tubular crystals via a novel solvent-relief-self-seeding process

A novel solvent-relief-self-seeding (SRSS) process was applied to grow bulk polygonal tubular single crystals of Sb(2)E(3) (E = S, Se), using SbCl(3) and chalcogen elements E (E = S, Se) as the raw materials at 180 degrees C for 7 days in ethanol solution. The products were characterized by various techniques, including X-ray powder diffraction (XRD), scanning electronic microscope (SEM), transmission electronic microscope (TEM), electronic diffraction (ED), and X-ray photoelectron spectra (XPS). The calculated electrical resistivities of the tubular single crystals in the range 20-320 K were of the order of 10(5)-10(6) Omega cm for Sb(2)S(3) and 10(3)-10(4) Omega cm for Sb(2)Se(3), respectively. The studies of the optical properties revealed that the materials formed had a band gap of 1.72 eV for Sb(2)S(3) and 1.82 eV for Sb(2)Se(3), respectively. The optimal reaction conditions for the growth of bulk tubular single crystals were that the temperature was not lower than 180 degrees C and the reaction time was not shorter than 7 days. The possible growth mechanism of tubular crystals was also discussed.     

Regioselective synthesis of 1,2,3-triazole derivatives via 1,3-dipolar cycloaddition reactions in water

Reaction of an arylacetylene with an azide in hot water gave 1,4-disubstituted 1,2,3-triazoles in high yields, while similar reaction between a terminal aliphatic alkyne and an azide (except m-nitroazidobenzene) afforded a mixture of regioisomers with the ratio of 1,4- to 1,5-isomers ranging from 3:1 to 28.6:1. Reactions of m-nitroazidobenzene with either arylalkynes or aliphatic alkynes formed only 1,4-disubstituted derivatives in excellent yields.     

Amperometric Biosensor for Hydrogen Peroxide Based on Electrodeposited Sub-micrometer Gold Modified Glassy Carbon Electrode

IntroductionAmperometricbiosensorofhydrogenperoxideisofpracticalimportancebecauseofitswideapplicationsinchemical,biological,clinical,environmentalandmanyotherfields.Forimprovementofsensor抯quality,vari-ouskindsofchemicalmodificationmethodshavebeendevelopedforreducingredoxoverpotentialsofH2O2atelectrodesurfaces,increasingthedetectionsensitivity,linearrange,stabilityandlivetime.Ithasbeenshownthattheuseofsub-micrometersizedmetalparticlessuchasPt-blackcansignificantlyimprovethequalityofthebiosens…     

Determination of chlorogenic acid and rutin in cigarettes by an improved capillary electrophoresis indirect chemiluminescence system

An improved capillary electrophoresis indirect chemiluminescence system was employed for the determination of chlorogenic acid and rutin in cigarette samples. After being separated by capillary electrophoresis, the analyte zones were determined by indirect chemiluminescence of luminol-potassium hexacyanoferrate. In this system, luminol was added into running buffer solution and introduced at the head of separation capillary, and potassium hexacyanoferrate was introduced at the end of the capillary. A high potential buffer reservoir was constructed from a running buffer cell and an electrode buffer one, which were jointed with a frit, in order to avoid luminol electrolysis in high potential reservoir and the excursion of chemiluminescence baseline. A low potential flow reservoir was used to prevent electrode buffer solution from the contamination of chemiluminescence waste. Therefore, the proposed capillary electrophoresis-chemiluminescence system can avoid the electrolysis of chemiluminescence reagent, retain the stability of chemiluminescence baseline and prolong the working time of running and electrode buffer solutions. In addition, the matrix of cigarette sample solutions has also an inhibitory effect on the chemiluminescence intensity in the indirect detection, whereas the influence was not observed in the separation of standard solutions. After the correction of matrix inhibition and the calibration with standard addition method, chlorogenic acid and rutin were determined in four cigarette samples by the improved capillary electrophoresis-chemiluminescence system.     

Modelling study of electron-beam polycyclic and nitro-polycyclic aromatic hydrocarbons treatment

The efficiency of the electron-beam removal of harmful impurities from industrial flue gases was studied as applied to polycyclic and nitro-polycyclic aromatic hydrocarbons. The mathematical model of radiation-induced processes was proposed. The model includes aromatic molecules decomposition in gas-phase reactions, and their liquid-phase conversion in the aerosol droplets produced upon the binary volume condensation of water and sulfuric acid vapors. The presence of active species (atoms and radicals) in radiation zone and their reactions with aliphatic and aromatic hydrocarbons can result in an opposite effect: the formation of aromatic molecules and growth of their structure. Modelling study of such processes allows evaluating the efficiency of this purification technology at various initial conditions. Results of calculations are compared with available experimental data.     

Preparation and thermal properties of a novel flame-retardant coating

A novel silicone and phosphate modified acrylate (DGTH) was synthesized and characterized by ¹H NMR and FTIR. It was found that DGTH could be cured both by UV radiation and moisture mode with FTIR. The flammability and thermal behavior of the cured film were studied by the limited oxygen index (LOI), thermogravimetric analysis (TG) and real time Fourier transform infrared (RT-FTIR). The LOI value of the cured film is 48 and the TG data shows that the cured film has three characteristic degradation temperature regions, attributing to the decomposition of phosphate and polyurethane to alcohols and isocyanates, thermal pyrolysis of alkyl chains, and decomposition of unstable structures in char, respectively. The RT-FTIR data implies that the degraded products of phosphate form poly(phosphoric acid) further catalyse the breakage of carbonyl groups to form an intumescent char, preventing the samples from further burning.     

Preparation of selective micro glucose sensor without permselective membrane by electrochemical deposition of ruthenium and glucose oxidase

A carbon fiber microelectrode, surface of which ruthenium and glucose oxidase (GOx) were electrochemically codeposited, has been investigated. The Ru deposition onto the microelectrode increased current response to H₂O₂ oxidation, while decreased oxidation currents due to interfering substances, such as ascorbic acid, uric acid, p-acetamidophenol, l-cysteine and dopamine. The codeposition of Ru and GOx gave further suppression of the interfering signals with keeping the current response to H₂O₂. When amperometric glucose sensing was conducted by using the GOx and Ru modified microelectrode, an increase in GOx concentration in the deposition bath enlarged oxidation current of H₂O₂ generated from glucose oxidation by GOx. The presence of ascorbic acid in analyte gave no error in detection of glucose and errors caused by uric acid was +3% at the most for measuring 5 mM glucose, which is the normal physiological level in blood.