Formation of titanate nanostructures under different NaOH concentration and their application in wastewater treatment

The effects of the concentration of NaOH on the formation and transformation of various titanate nanostructures were studied. With increasing NaOH concentration, three different formation mechanisms were proposed. Nanotubes can only be obtained under moderate NaOH conditions, and should transform into nanowires with prolonged hydrothermal treatment, and their formation rate is accelerated by increasing NaOH concentration. Low concentration of NaOH results in the direct formation of nanowires, while extra high concentration of NaOH leads to the formation of amorphous nanoparticles. Adsorption and photocatalysis studies show that titanate nanowires and nanotubes might be potential adsorbents for the removal of both heavy metal ions and dyes and photocatalysts for the removal of dyes from wastewater.     

Differential pulse anodic stripping voltammetric determination of Cd and Pb at a bismuth glassy carbon electrode modified with Nafion, poly(2,5-dimercapto-1,3,4-thiadiazole) and multiwalled carbon nanotubes

A simple, cheap, and nonpolluting method was developed for the cloud point extraction of gold (Au) and palladium (Pd). It is based on the complexation reaction of Au and Pd with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) and micelle mediated extraction of the complex using the non-ionic surfactant poly(ethylene glycol) mono-p-nonylphenyl ether (PONPE 7.5). Under the optimized experimental conditions, the enrichment factors are 16 and 17 for Au and Pd, respectively, for 15?mL of preconcentrated solution. The limits of detection are 3.8???g?L^?1 and 1.8???g?L^?1 for Au and Pd, respectively. The relative standard deviations are 1.4% for Au and 0.6% for Pd (n?=?11). The method was successfully applied to the determination of Au and Pd in certified reference materials and mine samples.

Preparation and characterization of attapulgite-silver nanocomposites,and their application to the electrochemical determination of nitrobenzene

Microchimica Acta - The surface of attapulgite was cleaned, modified with 3-aminpropyltriethoxysilane, and then covered with silver nanoparticles. The structure and morphology of the modified...     

Native biofilm cultured under controllable condition and used in mediated method for BOD measurement

In this article, we developed a native biofilm (NBF) bioreactor used for biochemical oxygen demand mediated method (BOD_Med). There were two innovations differed from previous BOD_Med assay. Firstly, the immobilization of microorganisms was adopted in BOD_Med. Secondly, the NBF was introduced for BOD measurement. The NBF bioreactor has been characterized by optical microscopy. A culture condition of NBF with 24 h, 35 °C and pH 7 was optimized. Furthermore, a measuring condition with 35 °C, pH 7 and 55 mM ferricyanide in 1 h incubation were optimized. Based on the optimized condition, the real wastewater samples from local sewage treatment plant had been measured. Performances of the NBFs proposed at different culture conditions were recorded for 110 d, and the results indicated that long-term storage stability was obtained. With the proposed method, an uncontaminated native microbial source solution can be obtained from a wastewater treatment plant. In this way, we can ensure that the microbial species of all in the NBF are same as that in the target to be measured.     

N-{4-{N-甲基-N-[2-羟基-3-(2,4-二氧代-1,2,3,4-四氢嘧啶-5-基)氨基]丙基}氨基-3-溴}苯甲酰基-L-谷氨酸二乙酯及其衍生物的合成

报道了N-{4-{N-甲基-N-[2-羟基-3-(2,4-二氧代-1,2,3,4-四氢嘧啶-5-基)氨基]丙基}氨基-3-溴}苯甲酰基-L-谷氨酸二乙酯及其衍生物的简便合成方法. 分别以4-氨基苯甲酸乙酯和4-氨基苯甲酰基-L-谷氨酸二乙酯为起始物, 经甲基化、烯丙基化、溴羟基化、环氧化、开环、脱保护等反应首次合成了6个新型5-取代氨基嘧啶类化合物, 并通过¹H NMR, ¹³C NMR 和MS对其化学结构进行了表征. 初步生物活性结果表明, 苯环侧链的L-谷氨酸酯部分是此类化合物抑制人重组二氢叶酸还原酶的必需结构.     

High speed injection molding of high density polyethylene �� Effects of injection speed on structure and properties

Thin wall samples of high density polyethylene (HDPE) were prepared via injection molding with different injection speeds ranging from 100 mm/s to 1200 mm/s. A significant decrease in the tensile strength and Young??s modulus was observed with increasing injection speed. In order to investigate the mechanism behind this decrease, the orientation, molecular weight, molecular weight distribution, melt flow rate, crystallinity and crystal morphology of HDPE were characterized using two-dimensional wide-angle X-ray diffraction (2D-WAXD), gel permeation chromatography (GPC), capillary rheometry and differential scanning calorimetry (DSC), respectively. It is demonstrated that the orientation, molecular weight, molecular weight distribution, melt flow rate and crystallinity have no obvious change with increasing injection speed. Nevertheless, the content of extended chain crystals or large folded chain crystals was found to decrease with increasing injection speed. Therefore, it is concluded that the decrease in tensile properties is mainly contributed by the reduced content of extended chain crystals or large folded chain crystals. This study provides industry with valuable information for the application of high speed injection molding.     

A new phosphine oxide host based on ortho-disubstituted dibenzofuran for efficient electrophosphorescence: towards high triplet state excited levels and excellent thermal, morphological and efficiency stability

An efficient host for blue and green electrophosphorescence, 4,6‐bis(diphenylphosphoryl)dibenzofuran ( o‐ DBFDPO ), with the structure of a short‐axis‐substituted dibenzofuran was designed and synthesised. It appears that the greater density of the diphenylphosphine oxide (DPPO) moieties in the short‐axis substitution configuration effectively restrains the intermolecular interactions, because only very weak π–π stacking interactions could be observed, with a centroid‐to‐centroid distance of 3.960 Å. The improved thermal stability of o‐ DBFDPO was corroborated by its very high glass transition temperature (T_g) of 191 °C, which is the result of the symmetric disubstitution structure. Photophysical investigation showed o‐ DBFDPO to be superior to the monosubstituted derivative, with a longer lifetime (1.95 ns) and a higher photoluminescent quantum efficiency (61 %). The lower first singlet state excited level (3.63 eV) of o‐ DBFDPO demonstrates the stronger polarisation effect attributable to the greater number of DPPO moieties. Simultaneously, an extremely high first triplet state excited level (T₁) of 3.16 eV is observed, demonstrating the tiny influence of short‐axis substitution on T₁. The improved carrier injection ability, which contributed to low driving voltages of blue‐ and green‐emitting phosphorescent organic light‐emitting diodes (PHOLEDs), was further confirmed by Gaussian calculation. Furthermore, the better thermal and morphological properties of o ‐DBFDPO and the matched frontier molecular orbital (FMO) levels in the devices significantly reduced efficiency roll‐offs. Efficient blue and green electrophosphorescence based on the o ‐DBFDPO host was demonstrated.     

Hybrid gold-nanoparticle-cored conjugated thiophene dendrimers: synthesis, characterization, and energy-transfer studies

A series of hybrid Au-nanoparticle-dendrimer materials: nanoparticle-cored thiophene dendrimers (NCTDs) were synthesized, characterized, and investigated for their energy-transfer properties. These hybrid nanoparticles were obtained by the simultaneous and in situ reduction of gold(III) chloride and self-assembly of the thiol-containing thiophene dendritic ligands. The dendron ligands were radially attached to the gold nanoparticles and were analyzed by TEM, UV/Vis, (1)H NMR, and FTIR spectroscopies. The solution fluorescence of the attached thiophene dendrons are quenched progressively. Both alkyl-chain length and dendron size have significant influence on the energy-transfer efficiency, as well as on core sizes and size distribution of the Au nanoparticles. In spite of the phenomenon's dependence on nanoparticle size, the energy transfer generally follows the 1/d(2) distance dependence. Single NCTD nanoparticles were also adsorbed on highly ordered pyrolytic graphite (HOPG) and uniform aggregates were observed on mica flat substrates.