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Zhao W.J.,Lanzhou University of Technology | Wang L.R.,Lanzhou University of Technology | Zhan G.L.,Gansu Dayu Water saving Group Co. | Li N.,Lanzhou University of Technology | Wang F.,Lanzhou University of Technology
Advanced Materials Research | Year: 2013

Gravel-mulched field is a unique mode of conservation tillage created by the working people with gravel as cover material and dependent on natural rainfall. However, with the growth of the planting years of the gravel-mulched field, the ecological effects gradually reduce. Thus, on the basis of the analysis to summarize the type and the thickness of gravel-mulched field, the insulation effect of gravel-mulched field to farmland, the water retention properties, the suppressing salinity function, anti-wind and water erosion capacity and increase production and income etc., we must attach importance to increase the replenishment fertilization to gravel-mulched field, improve the planting patterns of gravel-mulched field, select new varieties of drought-resistant crops, establish modern water-saving supporting system of the gravel-mulched field and other management measures and recommendations of ecosystem to provide a theoretical basis for sustainable development of gravel-mulched field agriculture. © (2013) Trans Tech Publications, Switzerland.


Jia X.,Shihezi University | Zhang G.,Shihezi University | Zhang G.,Gansu Dayu Water saving Group Co. | Li W.,Shihezi University | And 2 more authors.
Journal of Polymer Science, Part A: Polymer Chemistry | Year: 2014

A nondestructive method was developed for grafting and retrieving polymer brushes from single-walled carbon nanotubes (SWCNT)s based on mussel-inspired chemistry. Thermo-responsive polymer brushes were grafted on SWCNTs by coating the tubes with polydopamine as a reactive underlayer and sequential surface-initiated atom transfer radical polymerization of oligo(ethylene glycol) methacrylate (OEGMA, Mn = 475) and 2-(2'-methoxyethoxy)ethyl methacrylate (MEO2MA). Copolymer brushes were retrieved from the SWCNTs using 1 M NaOH to destroy the crosslinked polydopamine coating, and after that, the pristine properties of the SWCNTs were preserved. The low critical solution temperature (LCST) and molecular weight of the copolymer were measured using a nephelometer and gel permeation chromatograph, respectively. The loading and release behavior of Rhodamine 6G on responsive polymer-grafted SWCNTs demonstrates that the copolymer brushes confer the SWCNTs an LCST dependence. This method can accurately confirm the molecular weights and polydispersity of stimuli-responsive polymers grafted on any other nanoparticles and predict their controlled release behavior. Copyright © 2014 Wiley Periodicals, Inc.


Hu J.,Shihezi University | Jia X.,Shihezi University | Li C.,Shihezi University | Ma Z.,Shihezi University | And 4 more authors.
Journal of Materials Science | Year: 2014

In this work, graphene oxide (GO) and poly(methyl methacrylate) (PMMA) grafted GO reduced by dopamine (rGO@PDA-g-PMMA) were employed to determine the key factor responsible for the improved mechanical properties of poly(vinyl chloride) (PVC). Dopamine was utilized to reduce GO and simultaneous coating of polydopamine (PDA) on the GO surface. rGO@PDA-g-PMMA was prepared by a combination of mussel-inspired chemistry and surface-initiated atom transfer radical polymerization techniques. The resulting derivatives were characterized by thermogravimetric analysis, Fourier transforms infrared spectroscopy, X-ray diffraction, and Raman spectroscopy. PVC nanocomposites containing GO derivatives were prepared by solution blend and the nanocomposite films were obtained using a casting method. The mechanical properties of the nanocomposites were studied using both dynamic mechanical thermal analysis and tensile testing. The results revealed that the vital components responsible for the improved mechanical properties and thermal stability of rGO@PDA-g-PMMA/PVC nanocomposites compared to pure PVC are the interfacial interactions between the GO derivatives and the PVC matrix. © 2014 Springer Science+Business Media New York.


Sheng W.-B.,Shihezi University | Li W.,Shihezi University | Zhang G.-X.,Shihezi University | Zhang G.-X.,Gansu Dayu Water saving Group Co. | And 3 more authors.
New Journal of Chemistry | Year: 2015

Avermectin is susceptible to oxidation and photolysis, resulting in instability under UV irradiation and a short half-life. To solve this problem, many materials have been used to prevent the photodegradation of avermectin, but the complexity of the preparation process, the difficultly in biodegradation and the residual organic solvents, hinder their practical application. Fortunately, PDA emerged with negligible toxicity, environmental friendliness, extraordinary biocompatibility, and good adhesion, and it is widely used, especially as an UV-shielding material, which implies its huge potential in pesticides as a preferred candidate to melanin but this has never been reported. Herein, a gentle and flexible approach to the preparation of PDA coated avermectin was developed, to protect avermectin from photodegradation, through the oxidation self-polymerization of dopamine. The thickness of the polymer coating was controlled using a multistep deposition technique. The as-prepared products were used to study the effects of the coating thickness on the controlled-release and the UV-shielding property for avermectin. The results showed that the release rate of avermectin could be tailored using the thickness of the PDA layer. Most importantly, the PDA coating exhibited remarkable UV-shielding properties for avermectin, and the UV protection of the PDA layer for avermectin was improved with the coating getting thicker. Therefore, the system has a promising future in practical applications, so as to achieve sustained release and prevent the photodegradation of pesticides. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015.


Zhang X.,Shihezi University | Jia X.,Shihezi University | Zhang G.,Gansu Dayu Water saving Group Co. | Hu J.,Shihezi University | And 4 more authors.
Applied Surface Science | Year: 2014

This study reported a new method for efficient removal of Hg2+ from contaminated water using highly selective adsorptive polydopamine (PDA) nanospheres, which were uniform and had a small diameter (150-200 nm). The adsorption isotherms, kinetics, thermodynamics were investigated. Also, the effects of ionic strength, co-existing ions on removing ability of PDA nanospheres for Hg2+ were studied. Adsorption of Hg2+ was very fast and efficient as adsorption equilibrium was completed within 4 h and the maximum adsorption capacities were 1861.72 mg/g, 2037.22 mg/g, and 2076.81 mg/g at 298 K, 313 K, and 328 K respectively, increasing with increasing of temperature. The PDA nanospheres exhibited highly selective adsorption of Hg2+ and had a total desorption capacity of 100% in hydrochloric acid solution, pH 1. The results showed that the structure of PDA nanospheres remained almost unchanged after recycling five times. Furthermore, X-ray photoelectron spectroscopy (XPS) was employed to determine the elements of PDA nanospheres before and after Hg2+ adsorption. Considering their efficient and highly Hg2+ selective adsorption, total recycle capacity, and high stability, PDA nanospheres will be feasible in a number of practical applications. © 2014 Elsevier B.V.

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