A series of aromatic copolyimides was successfully synthesized from the commercial pyromellitic dianhydride (PMDA) with a commercial diamine p-phenyldiamine (PDA) and a diamine 4,4´-methylenebis-(2-tert-butylaniline

The synthesis of high-nitrogen energetic material 3,3´-azobis (6-amino-1,2,4,5-tetrazine) (DAAT) from 3,6-bis (3,5-dimethylpyrazol-1-yl)-1,2,4,5-tetrazine by a four-step reaction is described. The thermal properties of DAAT

Electrically conductive composites were prepared via the chemical oxidative polymerization of the pyrrole monomer in polystyrene (PS) and zinc neutralized sulfonated polystyrene (Zn-SPS) films under supercritical carbon dioxide (S

Fibrillar conductive polyaniline/TiO₂ (PANI/TiO₂)nanocomposites with different TiO₂ amount were synthesized with a template-free in situ polymerization method and characterized by transmiss

The title compounds were synthesized via N-benzylmalonamic acid methyl ester (3). As the key intermediate, 3 was prepared from methyl malonyl chloride and benzylamine. Then, compound 3 was reacted with dimethylformamide dimethyl acetal yielding vinylogue amides 4 and 5. Isomers 4 and 5 were respectively treated with amidine and guanidine to afford the title compounds 2-substituted pyrimidinone-5-carboxylic acid benzylamides 6 and 7. All of the new compounds were characterized by ¹H-NMR (nuclear magnetic resonance), ¹³C-NMR, MS and High Resolution Mass Spectrometer (HRMS). The antitumor activities of the compounds were tested in vitro against LoVo cells and Hep3B cells. Both compounds 6 and 7 show activity against these two cell lines.

Bismuth silicate (Bi₄Si₃O₁₂) nanopowders were prepared by the sol-gel method. Tetraethyl orthosilicate (TEOS) and Bi₂O₃ were used as the starting materials. The precursors were heat-treated at 750°C for 2 h. The size distribution of Bi₄Si₃O₁₂ nanopowders is 40?100 nm. The thermogravimetry and differential thermal analysis (TG-DTA) curves, the X-ray diffraction (XRD) patterns and the transmission electron microscopy (TEM) microphotograph of Bi₄Si₃O₁₂ were discussed. Compared with crystal materials, the excitation and emission spectra of Bi₄Si₃O₁₂ nanopowders indicated a blue shift.

Thermo-sensitive poly (N-isopropylacrylamide) (PNIPA) hydrogel with fast response rate was prepared by polymerizing N-isopropylacrylamide (NIPA) in an aqueous hydroxyl-propyl-methyl cellulose solution. The volume phase transition temperature of PNIPA hydrogels was characterized by differential scanning calorimetry (DSC), and the surface morphology was observed by scanning electron microscopy (SEM). The swelling ratios of the hydrogels at different temperatures were measured. Furthermore, the deswelling kine tics of the hydrogels was also studied by measuring their water retention capacity. In comparison with a conventional PNIPA hydrogel prepared in water, the hydrogel synthesized in aqueous hydroxyl-propyl-methyl cellulose solution has higher swelling ratios at temperatures below the lower critical solution temperature and exhibits a much faster response rate to temperature changes. For example, the hydrogel made in aqueous hydroxyl-propyl-methyl cellulose solution lost 89% water within 1 min and about 93% water in 4 min, whereas the conventional hydrogel lost only about 66% water in 15 min from the deswelling measurement in similar conditions.

An evaluation method for the capacity of antioxidants to protect drugs against oxidation is presented. As a new viewpoint, to determine the priority of the competitive oxidations between the antioxidant and the protected drug, and to compare the drug-protection capacity of antioxidants, it is important to determine their oxidation rate constants using chemical kinetics instead of standard oxidation (or reduction) potentials. Sodium sulfite, sodium bisulfite and sodium pyrosulfite were used as models for the determination of oxidation reaction rate constants in aqueous solutions. In the experiments, sufficient air was continually infused into the solution to keep the concentration of dissolved oxygen constant. The residual concentrations of the antioxidants were determined by iodimetry, and the concentration of dissolved oxygen by oxygen electrode. The data were fitted by linear regressions to obtain the reaction rate constants. It was found that the degradation of sodium sulfite, sodium bisulfite or sodium pyrosulfite obeyed pseudo zero-order kinetics in the buffer solutions. Because of the ionization equilibrium, these three antioxidants have the same ion form in solutions at a definite pH value and therefore their apparent rate constants were essentially the same. The average apparent rate constants of the three antioxidants at 25?C are (1.34?0.03)?10^-3 at pH 6.8, (1.20?0.02)?10^-3 at pH 4.0 and (6.58?0.02)?10^-3 mol °L^-1° h^-1 at pH 9.2, respectively.

A novel amperometric choline biosensor has been fabricated with choline oxidase (ChOx) immobilized by the sol-gel method on the surface of multi-walled carbon nanotubes (MWCNT) modified platinum electrode to improve the sensitivity and the anti-interferential property of the sensor. By analyzing the electrocatalytic activity of the modified electrode by MWCNT, it was found that MWCNT could not only improve the current response to H₂O₂ but also decrease the electrocatalytic potential. The effects of experimental variables such as the buffer solutions, pH and the amount of loading enzyme were investigated for the optimum analytical performance. This sensor shows sensitive determination of choline with a linear range from 5.0×10^-6 to 1.0×10^-4 mol/L when the operating pH and potential are 7.2 and 0.15 V, respectively. The detection limit of choline was 5.0×10^-7 mol/L. Selectivity for choline was 9.48 μA · (mmol/L)^-1. The biosensor exhibits excellent anti-interferential property and good stability, retaining 85% of its original current value even after a month. It has been applied to the determination of choline in human serum.

A new kind of ultraviolet (UV) curable waterborne polyurethane acrylate dispersion was synthesized based on hydroxyl-terminated polybutadiene (HTPB), poly-(propylene glycol) (PPG), isophorene diisocyanate (IPDI), 2-hydroxy ethyl acrylate (HEA) and dimethylol propionic acid (DMPA) after neutralizing by triethylamine (TEA). 2-Hydroxy-1-[4-(2-hydroxyethoxy) phenyl]-2-methyl-lpropanone (Irgacure 2959) was used as a photoinitiator and deionized water as a diluent. Fourier transform infrared (FTIR) analysis was used to identify the chain structure of the UV-curable polyurethane prepolymer based on HTPB and the curing process. Effects of relative content of HTPB and PPG on emulsion stability, resistance to water and ethanol, thermal stability, compatibility of soft and hard segment, as well as the mechanical property of the cured film were investigated.

The water behavior on (001) and (100) crystal faces of hydroxyapatite (HAP) were studied using molecular dynamics (MD) simulations. The study showed that the water molecules between the HAP faces were under conditions of strong electrical field and high pressure, and hence formed 2 3 well-organized water layers on the crystal surfaces. These structured water layers had ice-like features. Compared with the crystallographic [100] direction of HAP, the polarity along the [001] direction was stronger, which resulted in more structured water layers on the surface. The interaction of water molecules with the calcium and phosphate sites at the HAP-water interface was also studied. The results indicated the multiple pathways of water adsorption onto the HAP surfaces. This study revealed the formation and the detailed structure of water layers on HAP surfaces and suggested that the interfacial water played an important role in stabilizing the HAP particles in aqueous solutions.

Triazinone is a kind of heterocyclic compound with potential biological activity. The molecular design, synthesis and optimization of lead compounds are important to the development of insecticides. Six new triazinone derivatives were synthesized and characterized by IR, ¹H-NMR and MS spectra. The mechanism of synthesis of aminotriazinone was discussed.

Three new cobalt complexes were synthesized by solid-state reaction at room temperature and the resultant Co complexes reacted with two equivalent oxygen molecules at room temperature to produce the oxygenated complexes [Co° (L₁)₂ °(O₂)₂](NO₃)₂ °2H₂O (L₁ = N, N´-bis(4-hydroxyl-3-methoxy-benzyl)-diethylenetriamine), [Co ° (L₂)₂° (O₂)₂] (NO₃)₂ ° 2H₂O (L₂ = N, N´-bis(4-hydroxyl-3-methoxybenzyl)-triethylenetetramine), and [Co ° (L₃)₂ ° (O₂)₂](NO₃)₂ °2H₂O (L₃ = N, N´-bis(4-hydroxyl-3-methoxy-benzyltetraethylenepentamine). The oxygenated complexes were characterized by elemental analysis, IR (Infrared), ¹H-NMR (Nuclear Magnetic Resonance), and UV-Vis (Ultraviolet Visual) spectrometry, and TG/DTA (Thermogravimetry/Differential Thermal Analysis) analysis, and molar conductance. The coordinated oxygen contents in the oxygenated com plexes were also determined by weight method. It was supposed that only one O₂ molecule coordinated to the Co ion forming a superoxo type oxygenated complex.

The AFM-tip-induced crystallization of poly(ethylene oxide) (PEO) melt droplets was studied. The melt droplets with a height of 50 100 nm and a lateral size of 2 3 ?m were obtained by melting the PEO ultra-thin films on a mica surface. For the PEO samples with average molecular weights (M_n) ranging from 1.0?10³ g/mol to 1.0?10⁴ g/mol, the lateral perturbation from the AFM tip in the hard-tapping or nanoscratch modes could not induce the growth of the flaton lamellae. In contrast, under AFM nanoindentation mode, the tip-induced crystallization occurred when a sufficiently high vertical tip force was applied to the melt droplets of PEO with M_n"e1.0?10⁴ g/mol. Moreover, the experimental results indicated that the AFM-tip-induced crystallization of PEO in the nanoindentation process had molecular weight dependence.

A kind of biodegradable material, poly(ε-caprolactone-co-lactic acid) [P(CL-co-LA)] was synthesized via the direct melting polycondensation of lactic acid (LA) and ?-caprolactone (CL). The influences of the polycondensation time, and the catalyst type on the intrinsic viscosity of P(CL-co-LA) were also investigated. The results indicate that P(CL-co-dl-LA), with an intrinsic viscosity of 0.4733 dL/g, can be prepared by direct melting polycondensation with the molar ratio LA/CL = 3:7 at 180?C and 70 Pa for 12 h, using 0.5% (mass fraction) of SnCl₂ as the catalyst. Compared with lactide ring-opening polycondensation (ROP), the direct melting polycondensation of LA and CL is more practicable and simple.

In this paper, we call 3-N^ε-benzyloxycarbonyl-L-lysyl-morpholine-2,5-dione Compound A . The starting material used abroad is expensive and the yield is low (16% 28%); furthermore, to our best knowledge, no characterization of Compound A is available in the open literature. We now use low-cost L-lysine as starting material, succeed in raising the yield of Compound A to about 66%, and characterize it. In the synthesis of Compound A, the reactive processes used by us included the protection of amino group of lysine, acetylation, and intramolecular cyclizative condensation reaction. Benzoxycarbonyl chloride was selected as amino group protection agent, and the yield was elevated by replacing sodium bicarbonate with triethyl amide as the acid s neutralizer. The resulting material or Compound A was cyclizative; its structure and properties were characterized by infrared (IR), Differential Scanning Calorimetry (DSC), Nuclear Magnetic Resonance (NMR) and elemental analysis. The results of characterization show that: (1) Compound A has a chiral carbon next to the carbonyl group, so the formation of the ring structure is not stereospecific; (2) the melting point is about 254.5?C. The homopolymer and copolymers of Compound A with lactide or caprolactone have reaction-active groups and excellent biocompatibility and biodegradability; so they can be used in tissue engineering and as controlled-drug-release carriers.

A poly(vinyl alcohol) hydrogel was prepared by coupling poly(vinyl alcohol) with epichlorohydrin as the cross-linking agent. The structure of the hydrogel was characterized by FTIR and GPC techniques. Various amounts of water were

Densities have been measured for Glucose+HCl+Water at 10-degree intervals from 278.15 to 318.15 K. The apparent molar volumes (V_ε,G) and standard partial molar volumes (V_ε,G⁰ ) for Glucose in aqueous solution of 0.2, 0.4, 0.7, 1.1, 1.6, 2.1 mol° kg^-1 HCl have been calculated as well as volumetric interaction parameters (VEG) for Glucose-HCl in water and standard partial molar expansion coefficients (aV_ε,G0/aT)_p. Results show that (1) the apparent molar volume for Glucose in aqueous HCl solutions increases lineally with increasing molality of Glucose and HCl; (2) V_ε,G⁰ for Glucose in aqueous HCl solutions increases lineally with increasing molality of HCl; (3) the volumetric interaction parameters for Glucose-HCl pair in water are small positive and vary slightly with temperature; (4) the relation between V_ε,G⁰ and temperature exists as V_ε,G⁰ = ?0+?1(T-273.15 K)^2/3; (5) values of (aV_ε,G⁰/aT)_p are positive and increase as temperatures rise, and at given temperatures decrease slightly with increasing molalities of HCl, indicating that the hydration of glucose decreases with increasing temperature and molality of HCl. These phenomena are interpreted successfully by the structure interaction model.

A convenient method for the synthesis of tris-(2,2´-bipyridyl) dichlororuthenium(II) hexahydrate-doped amino-modified double-layer silica nanoparticles is presented in this paper. The synthesized nanoparticles are uniform and photostable, and can be well dispersed in a water solution. Proteins could be directly immobilized onto these nanoparticles by a simple coupling process without losing their biological activities. These nanoparticles were further used as fluorescent probes in protein microarray assay for the quantitative detection of protein. The results obtained by these nanoparticles, with the detection limit of as low as 3.5 μg/mL, were much better than those involving the use of conven tional FITC probe.

Nanometer MgO samples with high surface area, small crystal size and mesoporous texture were synthesized by thermal decomposition of MgC₂O₄·2H₂O prepared from solid-state chemical reaction between H₂C₂O₄·2H₂O and Mg (CH₃COO)₂·H₂O. Steam produced during the decomposition process accelerated the sintering of MgO, and MgO with surface area as high as 412 m²·g^-1 was obtained through calcining its precursor in flowing dry nitrogen at 520°C for 4 h. The samples were characterized by X-ray diffraction, N₂ adsorption, transmission electron microscopy, thermogravimetry, and differential thermal analysis. The as-prepared MgO was composed of nanocrystals with a size of about 4-5 nm and formed a wormhole-like porous structure. The MgO also had good thermal stability, and its surface areas remained at 357 and 153 m²·g^-1 after calcination at 600 and 800°C for 2 h, respectively. Compared with the MgO sample prepared by the precipitation method, MgO prepared by solid-state chemical reaction has uniform pore size distribution, surface area, and crystal size. The solid-state chemical method has the advantages of low cost, low pollution, and high yield, therefore it appears to be a promising method in the industrial manufacture of nanometer MgO.

In this paper, the electro-analysis and spectrophotometric analysis methods were used to study the antibacterial ability of copper and stainless steel materials. When Escherichia coli (E. coli) and photo-bacteria were used as samples, the antibacterial effect of stainless steel was very weak, while the percentage of bacteria dying from exposure to metallic copper for 30 min was over 90%. The antibacterial ability of copper has a potential application in the field of disinfection, food packaging and piping of drinking water.

A Waugh type polyoxometalate H₁₂[Mn-Mo₉O₃₂(KO)₆] has been synthesized and characterized by single crystal X-ray diffraction, IR, XRD and TG. The compound was crystallized in the trigonal system, space group R3 with a = 15.5380(6) nm, b = 15.5380(6) nm, c = 12.3777(5) nm, α = 90°, β = 90°, γ = 120°, V = 2587.98(18) nm³, Z = 3, R₁ = 0.0134, ωR₂ = 0.0308. The catalytic activity of the title compound for the dehydration of cyclohexanol was determined. The conversion of C₆H₁₁OH reached 69.56% and the selectivity of C₆H₁₀ was 96% when the amount of catalyst, temperature range and reaction time were 6.59%, 170°C?180°C, 30 min, respectively.

A new method for the preparation of 9-β-D-2´-deoxyribofuranosyl-6-methylpurine from inosine (1) is described. Inosine was converted to 6-chloropurinenucleoside (4) via acetylation, chlorination, and deacetylation. Compound 4 was transformed to the key intermediate 6-methylpurinenucleoside (7) via protection of the 2´,3´,5´-hydroxy groups of 4 with 3,4-dihydropyran to give compound 5, then methylation at the 6-position of 5 with dimethyl copper lithium gave compound 6; depyranylation of 6 led to the subsequent selective protection of the 3´,5´-hydroxy groups of 7 with O[Si(I-Pr)2Cl]2 followed by reaction with phenyl chlorothionoformate to give compound 9. Compound 9 was then converted to the target compound 11 via 2´-deoxidation and 3´, 5´-desilylation. The structures of these products were identified by Mass Spectrum (MS), ¹H-NMR (Nuclear Magnetic Resonance) spectra and elemental analysis.

The effect of self-seeding nucleation on the crystallization behavior of poly(trimethylene terephthalate) (PTT) was studied. Differential scanning calorimetry (DSC) indicated that the crystallization temperature of PTT notably increased after self-seeding nucleation. Avrami equation was applied in the analysis of the isothermal crystallization process of PTT. The resulting average value of the Avrami exponent at n = 3.34 suggests that primary crystallization may correspond to a three-dimensional spherulitic growth. Selfseeding nucleation, leading to a decrease in active energy for crystallization and chain folding work, promotes the overall crystallization process of PTT.