Hydrogen Production via Hydrolysis and Alcoholysis of Light Metal-Based Materials:A Review

As an environmentally friendly and high-density energy carrier,hydrogen has been recognized as one of the ideal alternatives for fossil fuels.One of the major challenges faced by“hydrogen economy”is the development of efficient,low-cost,safe and selective hydrogen generation from chemical storage materials.In this review,we summarize the recent advances in hydrogen production via hydrolysis and alcoholysis of light-metal-based materials,such as borohydrides,Mg-based and Al-based materials,and the highly efficient regeneration of borohydrides.Unfortunately,most of these hydrolysable materials are still plagued by sluggish kinetics and low hydrogen yield.While a number of strategies including catalysis,alloying,solution modification,and ball milling have been developed to overcome these drawbacks,the high costs required for the“one-pass”utilization of hydrolysis/alcoholysis systems have ultimately made these techniques almost impossible for practical large-scale applications.Therefore,it is imperative to develop low-cost material systems based on abundant resources and effective recycling technologies of spent fuels for efficient transport,production and storage of hydrogen in a fuel cell-based hydrogen economy.

Size effect of lattice material and minimum weight design

The size effects of microstructure of lattice materials on structural analysis and minimum weight design are studied with extented multiscale finite element method（EMsFEM） in the paper. With the same volume of base material and configuration, the structural displacement and maximum axial stress of micro-rod of lattice structures with different sizes of microstructure are analyzed and compared.It is pointed out that different from the traditional mathematical homogenization method, EMsFEM is suitable for analyzing the structures which is constituted with lattice materials and composed of quantities of finite-sized micro-rods.The minimum weight design of structures composed of lattice material is studied with downscaling calculation of EMsFEM under stress constraints of micro-rods. The optimal design results show that the weight of the structure increases with the decrease of the size of basic sub-unit cells. The paper presents a new approach for analysis and optimization of lattice materials in complex engineering constructions.

Infrared Emissivity of La0.8Sr0.2MnO3 with Three Different Structures

La_（0.8）Sr_（0.2）MnO_3 samples with rhombohedral, orthohombic and monoclinic structures were prepared by solid state reaction, sol-gel and co-precipitation methods, respectively. Lattice parameters, grain size, morphology, infrared absorption and emissivity of samples were investigated. The results indicated that the average crystallite size calculated from XRD result and particle size of orthohombic sample were smaller than those of the other two samples, and honeycomb shape grains were observed in orthohombic sample. Due to lower crystal symmetry, Mn-O stretching vibration peaks of the three samples shifted to higher infrared wavenumber. According to the theory of wave optics and Kirchhoff law, bigger rhombohedral sample showed higher emissivity than monoclinic one. However, due to the honeycomb structure of orthohombic sample, repeated reflection and scattering led to the increase of absorption, and orthohombic sample exhibited the highest emissivity.

Visible Light Responsive DNA Thermotropic Liquid Crystals Based on a Photothermal Effect of Gold Nanoparticles

Solvent free DNA-surfactant melts are receiving continuous attractions in recent years.Their physical properties could be regulated via changing the alkyl chain length of surfactants.As an ideal external stimulus,light has been used in the regulation of mechanical properties of DNA thermotropic liquid crystal(TLC)containing an azobenzene motif,while in this case,the UV light is the only effective excitation source.However,in comparison with visible light,UV light causes damage to DNA and has low tissue-penetration efficiency problem.In this work,a new type of DNA-didodecyldimethylammonium bromide(DNA-DDAB)TLCs fabricating with gold nanoparticles(AuNPs)was demonstrated.The visible light-induced photothermal effect of AuNPs could change the mechanical properties of AuNPs/DNA-DDAB TLCs,as shown by clearly boundary motion activity and viscoelasticity change.Furthermore,the ratio of AuNPs and charge stoichiometry of DNA:DDAB also affected photocurrent generation property of these DNA melts.The development of this visible light responsive DNA melt might facilitate the related studies in biomedicine and biomaterials.

KrF excimer laser-fabricated Bragg grating in optical microfiber made from pre-etched conventional photosensitive fiber

A method to fabricate fiber Bragg grating （FBG） in an optical microfiber （OM） from a conventional photosensitive fiber is proposed in this letter. The cladding of a conventional photosensitive fiber is etched to 17 pro. The etched fiber is drawn to an OM 6μm in diameter. The photosensitivity of the fabricated OM is effectively reserved. A FBG in the OM （MFBG） is successfully fabricated using a KrF excimer laser at a fluence of 400 mJ/cm2 through a phase mask with a pitch of 1 089.3 nm. The reflectivity of the FBG is approximately 10%, and the 3-dB spectrum bandwidth is 0.13 nm. The concentration of brine is measured by immersing the MFBG in the liquid, and the minimum detectable refractive index variation can reach 7.2×10^-5 at a refractive index value of 1.33.

High-sensitivity temperature sensor based on Bragg grating in BDK-doped photosensitive polymer optical fiber

A single-mode polymer optical fiber （POF） with highly photosensitive core doped with benzil dimethyl ketal （BDK） is fabricated and used for writing Bragg grating through the two-beam interference method. The Bragg wavelength of the grating is about 1570 nm, while the full-width at half-maximum （FWHM） of the reflection peak is 0.3 nm. The temperature response of POF Bragg grating is theoretically analyzed and experimentally measured in contrast to silica optical fiber Bragg grating （FBG）. The result shows that the temperature character of POF Bragg grating is negative, which is opposite to the silica optical FBG. The absolute value of the temperature response of POF Bragg grating is one order of magnitude higher than that of the silica optical FBG, making POF Bragg grating appear to be very attractive for constructing temperature sensors with high resolution.

Low birefringence depressed cladding photosensitive fiber

The highly Ge-doped photosensitive fiber （PSF） has been widely used in the fabrication of fiber Bragg gratings （FBGs）. Its birefringence and cladding mode coupling characteristics greatly influence FBG＇s transmission feature in communication application areas. In this work, a new concept of the PSF is introduced which, along with an optimized birefringence design, a precisely controlled fabrication process, and a cladding mode depressed design, results in a written FBG with -25-dB clad mode-depressed ratio and a polarization mode dispersion value less than 0.045 ps.

Preparation and luminescence properties of a white emitting long afterglow luminous fiber based on FRET

A ternary luminous fiber with white light emitting was prepared. The fiber combined emission from Sr＋2ZnSi_2O_7：Eu^2＋,Dy3, SrAl_2O_4：Eu^2＋,Dy^3＋ and Rhodamine B in the ternary system. According to fluorescence resonance energy transfer（FRET）, Rhodamine B was applied to generate red emission. A novel FRET system among Sr_2ZnS i_2O_7：Eu^2＋,Dy^3＋, SrAl_2O_4：Eu^2＋,Dy^3＋ and Rhodamine B was introduced. The anticipated luminescence properties could be realized precisely by adjusting the ratio. The summaries of the main test results such as X-ray diffraction, CIE chromaticity diagram and fluorescence spectrophotometer were given, and an afterglow brightness tester was used as a microcomputer thermo-luminescent dosimeter. The brief outlines about some phenomena aspects and detailed physical descriptions as well as manuals were available. From the XRD analysis the result suggested that the lattice structure was not destroyed when milling and spinning. The sample of 6：4：0.1 with white light emitting showed good physical, mechanical and luminous performance.

Photosensitivity and photoluminescence of Sn/Yb codoped silica optical fiber preform

Sn/Yb codoped silica optical fiber preform is prepared by the modified chemical vapor deposition （MCVD） followed by the solution-doping method. Ultraviolet （UV） optical absorption, photoluminescence （PL） spectra under 978-nm laser diode （LD） pumping, and refractive index change after exposure to 266-nm laser pulses are obtained. There is only a little change in the PL spectra while a positive refractive index change up to 2×10^-4 is observed after 30-min exposure to 266-nm laser pulses. The results show that both of the peculiar photosensitivity of Smdoped silica and the gain property of Yb-doped silica fiber are preserved in the Sn/Yb codoped silica optical fiber preform. The experimental data suggest that the photosensitivity of the fiber preform under high energy density laser irradiation should be mainly due to the bond-breaking of oxygen deficient defects, while under relatively low energy density laser irradiation, the refractive index change probably originates from the photoconversion of optically active defects.