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Diamond/aluminum composites have the advantages of high thermal conductivity and low density, making them ideal cooling materials for aerospace electronic devices. However, there is a lack of comprehensive research on the factors influencing the thermal conductivity of diamond/aluminum composites, as well as their reliability. In view of the above problems, spark plasma sintering method was utilized to prepare diamond/aluminum composites with a thermal conductivity of 462 W/(m·K). It considered the effects of sintering temperature, holding time, and diamond particle size combination. Additionally, the heat spreader reliability of this diamond/aluminum composite in high and low temperature and vibration environment was studied. The results demonstrated that the diamond/aluminum composite effectively reduced the heat source temperature by 13 °C compared to aluminum alloy when subjected to a heat flux of 70 W/cm². Furthermore, diamond/aluminum composites can maintain stable physical properties and structural reliability in the high and low temperature and vibration environment, effectively exerting their heat dissipation capacity. Overall, diamond/aluminum composites can be presented as a reliable solution for heat dissipation in aerospace electronic devices. [ABSTRACT FROM AUTHOR]

Quantification of seepage in disconnected river-aquifer systems is significant for local water management and groundwater pollution control, especially in areas with water shortage or contamination. The vadose zone under riverbeds usually exhibits a multi-layered structure, particularly when paved with low permeability liners. To evaluate the impact of engineering solutions to seepage under such conditions, we proposed an approach by combining GIS and the minimum flux in saturation layer (MFSL) method. MFSL can calculate the stable seepage rate by assessing the dominant low permeability layers (including but not limited to the liners) in multi-layered disconnected river-aquifer systems. We used MFSL to calculate local seepage rate, and used GIS to extend the results to a regional scale. The reliability of MFSL is discussed by comparing the results with the double ring infiltration test, the numerical simulation by HYDRUS, and the methods of stream package in MODFLOW, including its improved form. A case study was conducted in the Yongding River with river-aquifer seepage calculated under various conditions, including different river water levels (i.e., under the designated water level, drought stage level, flood stage level and flood inundation level) and with/without low permeability liners (i.e., ecological membranes or geomembrane). Results showed that low permeability liners could greatly reduce the seepage rate. However, if an unlined inundation area exists, the seepage rate may increase greatly. The results indicated that the proposed method was reliable and convenient for calculating long-term, large area seepage in disconnected river-aquifer systems especially those paved with liners.

A versatile method is described to synthesize a new family of solvent-responsive membranes whose response states can be not only tunable but also fixable via ultraviolet ( UV) irradiation induced crosslinking. The atom transfer radical polymerization ( ATRP) initiator 2-bromoisobutyryl bromide was first immobilized on the poly(ethylene terephthalate) ( PET) track-etched membrane followed by room-temperature ATRP grafting of poly(2-hydroxyethyl methacrylate) ( PHEMA) and poly(2-hydroxyethyl methacrylate- co-2-(dimethylamino)ethyl methacrylate) (P( HEMA- co- DMAEMA)) respectively. The hydroxyl groups of PHEMA were further reacted with cinnamoyl chloride (a photosensitive monomer) to obtain photo-crosslinkable PET- g- PHEMA/ CA membrane and PET- g-P( HEMA/ CA- co- DMAEMA) membrane. The length of grafted polymer chains was controllable by varying the polymerization time. X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy in attenuated total reflection and thermogravimetric analysis were employed to characterize the resulting membranes. The various membrane surface morphologies resulting from different states of the grafted chains in water and dimethylformamide were characterized by scanning electron microscopy. It was demonstrated that the grafted P( HEMA/ CA- co- DMAEMA) chains had more pronounced solvent responsivity than the grafted PHEMA/ CA chains. The surface morphologies of the grafted membranes could be adjusted using different solvents and fixed by UV irradiation crosslinking. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

A dual stimuli-responsive (pH and thermo) polyethylene terephthalate (PET) track-etched membrane has been prepared using atom transfer radical polymerization (ATRP). First, ATRP initiator 2-bromoisobutyryl bromide was anchored onto the membrane surface. Then, 2-hydroxyethyl-methacrylate (HEMA) and N-isopropylacrylamide (NIPAAm) were grafted onto the membrane surface using ATRP. X-ray photoelectron spectroscopy, ATR-Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis were used to characterize the membrane structure and thermal properties; water flux measurement was used to investigate the double stimuli-responsive property of the obtained membrane. The results indicate that the PHEMA and PNIPAAm binary grafted PET track-etched membrane has double environmental responsiveness. This method provides a potential modification method for preparing functional membranes. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A novel Ag3AsO4 photocatalyst has been prepared via a facile precipitation method. It exhibited higher activity than Ag3PO4 or AgI in degradation of rhodamine B or methyl orange. The excellent activity of Ag3AsO4 is attributed to its more separated photogenerated carriers and high absorption capacity of visible light. [ABSTRACT FROM AUTHOR]