In this work, based on the ReaxFF-lg reactive force field, the effects of temperature and wax binder on RDX thermal conductivity were studied by using molecular dynamics simulation (MD). The non-equilibrium molecular dynamics (NEMD) method was used to calculate the heat transfer process of RDX crystals with different sizes and at different temperatures and for RDX/wax mixtures with different ratios. The contribution of acoustic and optical phonons to the thermal conductivity was calculated using a thermal conductivity decomposition procedure. The heat transfer process of the RDX supercell and the RDX/wax mixtures were analyzed via calculation of the vibrational density of states. The thermal conductivity of the RDX increased with increasing temperature while the temperature was below 298 K, and decreased slightly with increasing temperature while the temperature was above 323 K. The interfacial thermal resistance between RDX and wax was the main factor that led to a decrease in the thermal conductivity of the RDX/wax mixed explosives. Acoustic phonons played a major role for heat transfer in RDX and mixed RDX explosives. An increased temperature resulted in more frequent expansion or torsion of the bonds in the optical modes, resulting in a slight reduction in the thermal conductivity.

The photopolymer materials are good media to record thick hologram gratings, because photopolymer materials have high resolution, low cost, simple process technology and so on. According to coupled wave theory for thick hologram gratings, we know that the same object beam can be reconstructed if the same reference beam is used to retrieve a thick hologram grating. However, the shrinkage always occurs in the photopolymer materials because of environment temperature, humidity, vibration etc. For instance, the same object beam cannot be reconstructed even the same reference beam to be used. In this paper, we will analysis the shrinkage influence of photopolymer materials for thick hologram gratings. We divide the photopolymer materials into several geometry layers, and analysis the reconstructed characteristics separately basing on coupled wave theory of Kogelnik. Through gradually continuous changing the angle between gratings and the border (we call it slant angle), we can build the geometry model of gratings bending caused by shrinkage of materials. We calculate wave complex amplitude diffracted from every layer, and superpose them to compute the total diffraction efficiency. We simulate above methods to obtain the curve of diffraction efficiency with reconstruction wavelength by using Matlab software. Comparing the simulated results with the experiments results, we can deduce the probable situation of thick hologram gratings bending after photopolymer materials shrink.

We proposed a robust method for surface-functionalizing magnetic polyvinyl alcohol microspheres to detect heavy metal ions in aqueous solutions. The prepared chemosensor (PAR-MPVA) was characterized through scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectra (XPS). In neutral solutions, PAR-MPVA selectively recognized diatomic heavy metal ions, as indicated with a color change from earth yellow to red; in strong acidic solutions, the chemosensor only selectively detected Cu2+ PAR-MPVA microspheres had a detection limit as low as 0.5 mu M by naked-eye and 0.16 mu M by UV-vis spectrometer for Cu2+ Moreover, the sensor possessed magnetism for effective recovery, could easily be regenerated by a solution of EDTA, and also displayed perferable stability. The PAR-MPVA microspheres possessed preeminent properties of detecting copper (II) ions in aqueous solutions. (C) 2014 Elsevier B.V. All rights reserved.

Poly(vinyl alcohol) (PVA) microspheres were prepared by inverse suspension crosslinked method, with glutaraldehyde as a crosslinking agent. PVA microspheres activated with aldehyde groups were employed for Trametes versicolor laccase immobilization. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to characterize the activated PVA microspheres and PVA microspheres with immobilized laccase (Lac/PVA microspheres), which show that laccase was successfully immobilized on the PVA microspheres. The optimum pH and temperature coupling conditions for the immobilized laccase were determined to be 3.3 and 30 °C, respectively. Residual activity was also investigated by soaking the immobilized laccase in organic solvents at different concentrations, proving it chemically stable. Immobilized laccase exhibited good storage stability at 4 °C. The enzyme biosensor showed good performance in 2,2-azinobis(3-ethylthiazoline-6-sulfonate) and bisphenol A, with concentration ranges of 2 to 8 mM and 0.05 to 0.25 mM, respectively. Therefore, PVA microspheres may have high potential as support for enzyme thermistor applications.