Ecological impacts of water resources utilization in the tarim river basin of China

Water resources and ecosystem stability are the most conspicuous and sensitive issues in arid areas of China. In this paper, exploitation of water resourcesand the corresponding environmental problems in the Tarim River during the past five decades are evaluated. An increasing use of water in the source area caused problems withsecondary salinization of the soil; whilst an increasing consumption of water inthe upper- and middle-reach areas caused droughts in the lower-reach area. Serious water pollution intensifies scarcity of water resources. Groundwater levels have dropped substantially and ecosystems have been seriously damaged. The purposes of our studywere to reveal the relationship between exploitation of water resources and ecosystemsuccession, to put forward the measures for rationally utilizing the water resources and effectively protect the ecosystem integrity in the Tarim River watershed, and to provide the scientific basis for overall harnessing of the Tarim River. Copyright © 2007 IAHS Press. (7 refs.

R&D of comprehensive evaluation system of ecological environment in Tarim River basin

Comprehensive ecological environment evaluation system is an essential professional analysis system in Tarim River basin water regulation management. Research and development of the system consists of ecological environment quality evaluation module, ecological risk assessment module and ecological water demand module. The paper carries out environment quality evaluation by calculating bio-abundance index, vegetation coverage index, density index of network of rivers, land degradation index and pollution load index, and adopts "plant phreatic evaporation quota method" to calculate demand for ecological water in maintaining current situations of natural vegetation. By ecological risk evaluation thought and landscape ecology method, the paper makes calculation of ecological degradation index, risk index and restoration index respectively, and builds an ecological risk intensity index for corresponding ecological risk analysis and evaluation. It further explores the overall plan for system building, system function and structure and integration with other subsystems. Results show that it is very practical and operable to develop environmental information system with the theoretical study results and through ArcGIS +Oracle9 i + ArcSDE technology, and the development helps to make scientific evaluation on environment in arid area, and can offer certain reference for development of other relevant systems. © 2010 IEEE. (8 refs.

Co-doped ZnO dilute magnetic semiconductor thin films by pulsed laser deposition: Excellent transmittance, low resistivity and high mobility

Co-doped ZnO ceramic samples sintered at four different temperatures were prepared by solid-state reaction method and implanted by Al ions subsequently. The microstructural, defect, magnetic and electrical properties of the samples were systematically investigated by x-ray diffraction, micro-Raman spectroscope, vibrating sample magnetometer and Hall measurement, respectively. The results show that all the samples exhibit room-temperature ferromagnetism with a saturation magnetization of 0.02–0.03 emu g−1, the value of which is affected by the sintering temperature. The origin of room-temperature ferromagnetism is considered as the formation of Co2+– V O–Co2+ bound magnetic polarons. Even though the implantation of Al3+ slightly reduces the saturation magnetization because of the lattice damage, less V O and larger lattice spacing, however, an appropriate amount of Al3+ implantation and a proper sintering temperature can remarkably improve the electrical properties with the mobility of 200 ∼300 cm2 Vs−1 and the resistivity of 20 ∼40 Ω cm. In general, samples sintered at 1200∘C present more excellent comprehensive performances

Preparation and properties of perfluorosilane modified nano-silica / silicone rubber based triboelectric nanogenerator

"Silicone rubber (SR) is one of the most important polymer materials with unique viscoelasticity and toughness. In this work, the surface of nano-silica was modified by 1 H, 1 H, 2 H, 2 H-perfluorodecyltriethoxysilane to improve the dispersion of nano-silica in SR. Finally, the 1 H, 1 H, 2 H, 2 H-perfluorodecyltriethoxysilane modified nano-silica (F-SiO2) / SR composites were used to fabricate a serials F-SiO2 / SR based triboelectric nanogenerators (FR-TENG). 　The effect of F-SiO2 contents on the electric out-put performance of FR-TENG was studied. As shown in Table 1, at 1.0% (mass fraction, the same below) F-SiO2 content, the FR-TENG exhibited the best output performance. The short circuit current (Isc), open circuit voltage (Voc) and hort circuit transfer charge (Qsc) of FR-TENG at 1.0% F-SiO2 content were 5.5 μA, 244.1 V and 76.9 nC, compared with those of pure SR increased about 71%, 26% and 16%, respectively.The FR-TENG can be used to light up about 33 LED lamps, which working circuit diagram was shown in Fig 1. Therefore, the FR-TENG has a great potential application in the wind, ocean, and mechanical energy harvesting and convert this green energy into AC electricity. The AC electricity can be rectified to DC electricity through the rectifier bridge and stored in commercially available capacitors, which can be used to power electronic devices. In addition, a 22 μF commercially available capacitor was charged by the FR-TENG to 2.5 V and discharging by driving a small calculator (Fig 2).

Research advance in low-temperature resistant rubber: Molecular structure design and chemical modification

"Research progress in low-temperature resistant rubber materials was reviewed with 77 references, the molecular structures, low temperature resistance and influencing factors of natural rubber, general synthetic rubber and special synthetic rubber were compared, and the modification methods of low-temperature resistant rubber were summarized. Finally, the future development direction of low-temperature resistant rubber was prospected.

"Research progress in preparation of thermoplastic elastomers by living controlled polymerization"

Starting with polymerization methods such as anionic polymerization, cationic polymerization, ring-opening polymerization, and controlled free radical polymerization, the research progress of different types of thermoplastic elastomer synthesis technology was summarized with 55 references, as well as other new fields and new directions of thermoplastic elastomer research progress such as the combination of supramolecular chemistry and polymer synthesis

Design of Bipolar Mass Analyzer in Miniaturized Single Particle Aerosol Mass Spectrometry

Biological aerosols are a special type of aerosols in the atmosphere, which have carcinogenic and teratogenic properties. Real-time detection and identification of biological aerosols is the prerequisite for biological warning and forecasting. The design of bipolar time-of-flight (TOF) mass analyzer is required to realize miniaturized vehicle bioaerosol mass spectrometer, with the mass range above 300 and mass spectrometry resolution at least 500. In this study, the exponential pulse delay elicitation technique was applied to the design of miniaturized TOF. Combined with SIMION 2020 software, the particle flight trajectory under the condition that the velocity dispersion was a Gaussian distribution with a peak value of 800 m/s and a spatial dispersion of 0.3 mm were simulated. The particle swarm optimization algorithm (PSO) was used to automatically optimize the voltage and delay time of the TOF. Under the optimized delay time of 130 ns, the resolution of more than 500 could be achieved in the full mass range even if the spatial dispersion and energy dispersion were in extreme cases, and mass deviation between different particles could be controlled within 0.4 u. The impact of normal square wave pulse delay extraction and exponential pulse delay extraction on the resolution of ions formed by a single particle was compared and analyzed. The results showed that exponential pulse delay extraction improves the resolution in the full mass range significantly better than square wave pulse. The effect of particle ionization position on mass spectrometry resolution was simulated when the particle was in the center of the spot and at the limit of 0.15 mm to left and right of the spot. The result showed that the resolution was different, but still better than 500. The detection of black carbon particles showed that the miniaturized TOF could obtain a resolution of more than 500 in the full mass range, which met the resolution requirements of the vehicle bioaerosol mass spectrometer. Although the flight length of the small TOF is 67% of that of SPAMS 0525, the resolution could reach more than 1.2-1.7 times due to the use of exponential pulse delay extraction technology. This study provides a design for a small time-of-flight mass analyzer, and indicates that there is still room for further reduction the size of time-of-flight mass analyzer for the miniaturized bioaerosol mass spectrometry. This study lays a research foundation for further reduction the volume of the subsequent bioaerosol mass spectrometer