Impacts of water conservancy and soil conservation measures on annual runoff in the Chaohe River Basin during 1961-2005

National Key Technology RD Program [2006BAD03A02]

Macroscopic single-crystal tubes assembled with porous supramolecular architecture of water-soluble calixarene and phenanthroline

Single-crystal tubular products on the millimetre scale have been synthesized from water-soluble calixarene and phenanthroline in the presence of lanthanides by a hydrothermal method, in which the extended structures contain some 1D infinite channels.

Synthesis and properties of water stable poly[bis(benzimidazobenzisoquinolinone)] ionomers for proton exchange membranes fuel cells

A novel sulfonated tetraamine, di(triethylammonium)-4,4'-bis(3,4-diaminophenoxy)biphenyl-3,3'-disulfonate (BAPBDS), was successfully synthesized by nucleophilic aromatic substitution of 4,4'-dihydroxybiphenyl with 5-chloro-2-nitroaniline, followed by sulfonation and reduction. A high-temperature polycondensation of sulfonated tetraamine, non-sulfonated tetraamine (4,4 -bis(3,4-aminophenoxy)biphenyl) and 1,4,5,8-naphthalenetetracarboxylic dianhydride (a) or 4,4'-binaphthyl-1,1',8,8'-tetracarboxylic dianydride (b) gave the poly[bis(benzimidazobenzisoquinolinones)] ionomers SPBIBI-a(x) or SPBIBI-b(x), where x refers to the molar percentage of the sulfonated tetraamine monomer. Flexible and tough membranes of high mechanical strength were obtained by solution casting and the electrolyte properties of the polymers were intensively investigated. The ionomer membranes displayed excellent dimensional and hydrolytic stabilities.

"Dual-Parallel-Channel" Shape-Gradient Surfaces: Toward Oriented and Reversible Movement of Water Droplets

In this paper, we prepared "dual-parallel-channel" shape-gradient surfaces, on which water droplets can reversibly and orientedly move between two adjacent pools under the guidance of an external voltage. Furthermore, it is found that the motion speed is governed by several parameters, including bath condition, gradient angle, and the working voltage. In this self-transportation process of water droplets, the external voltage works like a traffic light, which can give "moving", "stopping", "turning" and "straight-going" signals to the Water droplets.

Cyclization of citronellal to p-menthane-3,8-diols in water and carbon dioxide

A clean process has been developed for the synthesis of p-menthane-3,8-diols from cyclization of citronellal in CO2-H2O medium without any additives. With the addition of CO2, the reaction rate could be enhanced about 6 times for the cyclization of citronellal in H2O, because CO2 dissolved into water and formed carbonic acid inducing an increase of the acidity. Although, the reaction conversion in CO2-H2O is slightly lower compared to that obtained with sulfuric acid as catalyst, CO2-H2O could replace the sulfuric acid at a relative higher reaction temperature. The reaction kinetics studies showed that the hydration of isopulegols to p-menthane-3,8-diols is a reversible reaction. The equilibrium constant and the maximum equilibrium yield obtained in CO2-H2O at a range of CO2 pressures are similar to that with sulfuric acid catalyst.

CNT Templated Regioselective Enzymatic Polymerization of Phenol in Water and Modification of Surface of MWNT Thereby

Carbon nanotubes (CNTs) are used as templates to synthesize regioselective polymers from enzymatic polymerization of phenol in water. About 90% of total polymeric units in the obtained polymers are the highly thermally stable oxyphenylene units. The polymer-yields are dependent on the quantities of CNTs used. On the basis of MWNT-templated enzymatic polymerization of phenol, covalent attachment of polyphenol chains to the surface of MWNT by way of a linking molecule, hydroquinone, is achieved. This approach supplies a novel way for producing high-performance polymers and for functionalization of the surface of CNT.

Synthesis, self-assembly in water, and cytotoxicity of MPEG-block-PLLA/DX conjugates

Docetaxel (DX) is one of the most effective antineoplastic drugs. Its current clinical administration is limited because of its hydrophobicity and Serious side effects. A polymer/DX conjugate is designed and successfully prepared to solve these problems. It is monomethoxy-poly(ethylene glycol)-block-poly(L-lactide)/DX (MPEG-PLLA/DX) It was synthesized by reacting DX with carboxyl-terminated copolymer MPEG-PLLA, which was prepared by reacting succinic anhydride with hydroxyl-terminated copolymer monomethoxy-poly(ethylene glycol)-block-poly (L-lactide) (MPEG-PLLA). Its structure and molecular weight was confirmed by H-1 NMR and GPC. The MPEG-PLLA/DX micelles in aqueous solution were prepared Using a SO]vent displacement method and characterized by dynamic light scattering for size and size distribution, and by transmission electron microscopy for surface morphology. Its antitumor activity against HeLa cancer cells evaluated by MTT assay showed that it had a similar antitumor activity to Pure D at the same drug content.

Photochemical formation of silver and gold nanostructures at the air-water interface and their electrocatalytic properties

In this paper, we report a simple method of fabricating silver and gold nanostructures at the air - water interface, which can be spontaneously assembled through the reduction of AgNO3 and HAuCl4 with ultraviolet (UV) irradiation in the presence of polyacrylic acid (PAA), respectively. It was found that the building blocks in the silver nanostructure are mainly interwoven silver nanofilaments, while those of the gold nanostructure are mainly different sizes of gold nanoparticles and some truncated gold nanoplates, and even coalescence into networks. At the air - water interface, these silver and gold nanostructures can be easily transferred onto the surface of indium tin oxide (ITO) slides and used for electrochemical measurements. After a replacement reaction with H2PdCl4, the silver nanostructure is transformed into a Ag - Pd bimetallic nanostructure, with good electrocatalytic activity for O-2 reduction. The gold nanostructure can also show high electrocatalytic activity to the oxidation of nitric oxide (NO) with a detection limit of about 10 mu M NaNO2 at S/N = 3.