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To systematically reveal the correspondence between surface properties and corrosion behaviors under mechanical conditions, an improved Butler-Volmer (IBV) electrochemical model is proposed by introducing the strain effects on electrochemical polarization through the scaled strain energy. Under mechanical straining, the three critical physical parameters i.e., surface energy, work function and strain energy, may be changed synergistically, which would consequently modify the exchange current density and equilibrium potential for the anode polarization curves. Taking two representative metals of Mg and Zn as a demonstration, it reveals that both tensile and compressive strain would contribute to the corrosion rate by lowering the activation energy barrier, in agreement with previous experimental observations. The improved model opens an alternative way to quantify the relationship between surface properties and corrosion behavior via intrinsic materials properties, which is beyond the normal design rules empirically based on either surface energy or work function alone. [Display omitted] • An improved Butler-Volmer model is presented to reveal the correspondence between surface properties and corrosion behaviors under straining. • The basal planes for pure Zn and Mg show much lower corrosion/degradation rates than the prism planes. • Both tensile and compressive strains can promote the corrosion/degradation of Zn and Mg. [ABSTRACT FROM AUTHOR]

The industrial applications of Mg and its alloys are restricted by their poor corrosion resistances, owing to the rapid dissolution and hydrogen evolution behaviors. In this study, a sequentially bridged reduced graphene oxide (RGO)/bistriethoxysilylethane (BTSE) coating is successfully grafted on the surface of Mg alloy substrate, to simultaneously inhibit the corrosion and wear behaviors. It exhibits well-aligned biomimetic nacre-like "bricks and mortar" structure connected by covalent bonding networks, consisting of the Si-O-C bonds between the RGO sheets and the Si-O-Si bonds derived from BTSE self-crosslinking reactions. The reduced porosity and defects lead to a high continuity and integrity of the RGO/BTSE coating, which decreases the corrosion rate by an order of magnitude compared with bare Mg substrate and RGO coated sample, owing to the enhanced barrier effect and weakened galvanic corrosion. In addition, the hybrid coating also performs well anti-wear property due to the intrinsic lubrication of RGO sheets, which can protect the substrate from friction and wear. The wear rate decreases from 3.5 × 10−3 mm3N-1 m-1 of bare Mg alloy to 5.13 × 10-5 mm3N-1 m-1 of RGO/BTSE coated sample. The interlayer slipping between the RGO sheets effectively decreases friction resistance, although the incorporation of BTSE slightly increases their shear resistance. [ABSTRACT FROM AUTHOR]

In order to expand the applied range of Mg alloy, a variety of coatings have been designed to improve their corrosion and wear resistance. Here, we report a 3-aminopropyl triethoxysilane (APTES) modified Mg(OH) 2 /reduced graphene oxide (RGO) hybrid coating with integrated anti-corrosion/wear property on Mg alloy, which is prepared by in-situ crystallization using a facile hydrothermal method. The ultra-thin Mg(OH) 2 /RGO layer with 250 nm exhibits a dual-structure, in which the inner layer is composed of Mg(OH) 2 , and then RGO sheets hybrid with Mg(OH) 2 via the hydrogen bond to form the outer layer. The lubrication of RGO sheets and the high hardness of dense Mg(OH) 2 give rise to the significant decrease of wear rate, which is two orders of magnitude less than that in Mg substrate. Next, the APTES layer effectively fills the pores and defects on the surface of Mg(OH) 2 /RGO via the Si-O-Mg and amide bond, and it forms a barrier film enriched with Si-O-Si bond via the self-crosslinking reaction. The effective combination of inorganic and organic layer contributes to the improved anti-corrosion property. Unlabelled Image • Ultra-thin Mg(OH) 2 /RGO-APTES film is constructed by a hydrothermal method. • The composite coating shows an integrated anti-corrosion/wear performance. • The enhanced barrier effect is ascribed to the cross-linking effect of APTES agent. • A dual-structure contributes to the decreased friction coefficient and wear rate. [ABSTRACT FROM AUTHOR]

• Packed 18,650 batteries deform in a different way from individual battery. • Tests show more serious damage under impact than slow speed compression. • Under simulation, four types of failure behaviors are discovered under dynamic collision. • Crushing velocity dominates the failure behavior rather than crushing energy under simulation. • Simulation shows that failure displacement dramatically decreases once crushing velocity exceeds 20 m/s. The mechanical and failure behaviors of individual 18,650 cylindrical battery have been studied in many papers recently, showing that the internal short-circuit of the battery can be induced by the mechanical load. In practice, the cylindrical batteries mostly work in a packed way and there is little research on the packed batteries. In the present paper, failure behaviors of packed batteries under both quasi-static compression and dynamic collision are investigated by tests. It is shown that the deformation of the packed batteries is very different from those of the individual ones. The failure of the packed batteries is caused by the nonuniform deformation within each battery, which creates vulnerable areas near the gap among batteries. Besides, it is found that the packed batteries under impact collision undergo distinguishing behaviors from those under quasi-static compression. Under quasi-static situations, the packed batteries deform uniformly and the failure batteries distribute randomly. However, under dynamic impact, the packed batteries are crushed row by row with force concentrating at some certain rows, which results in the heavier damage of the batteries under the same crushing displacement, meaning a higher failure risk. Then numerical simulations are employed to deeply investigate the dynamic mechanism of the packed batteries. Four types of failure behaviors are discovered for the packed batteries under dynamic collision, which are related to the stress wave propagation and give a good explanation on the complex dependence of the failure displacement of the packed batteries on the crushing speed. The results indicate that the crushing velocity dominates the failure behavior of the packed batteries rather than the crushing energy. The failure displacement of the battery pack will dramatically decrease once the crushing velocity larger than 20 m/s. More attention should be drawn on the dynamic safety of the packed batteries and the related safety standards also need to consider the complex dynamic collision. All the investigations may provide a basic foundation for the safety protection research of the packed batteries, which are helpful for electric vehicle industry and other structures with packed batteries. [ABSTRACT FROM AUTHOR]

Abstract: We have experimentally demonstrated an efficient diode pumped Tm:CLNGG disordered crystal laser operating at 2μm wavelength. The maximum output power of 1.6W was obtained with a slope efficiency as high as 37%. The spectrum of the free-running disordered crystal laser shows a wide emission bandwidth, which will benefit to ultrashort pulse generation by mode locking. Our results suggest that the Tm:CLNGG disordered crystal is a potential laser material for generation of ultrashort pulses at 2μm wavelength. [Copyright &y& Elsevier]

Abstract: The polarization Raman spectra were measured for the calcium-doped strontium barium niobate crystals ((Ca0.28Ba0.75)x(Sr0.60Ba0.40)1− x Nb2O6 (x =0.25,0.50 or 0.75, CSBN) to determine the negative thermal expansion(NTE) change induced by different stoichiometric proportions calcium-doped concentration. The different count-intensity (CI) of Raman peaks with the scattering geometry Z(XY)Z­, corresponding to the symmetry species B 2, are attributed to the different vacancy rate(VR) in A2 sites of tetragonal tungsten bronze-type structure, which can result in the change of the short-range molecular force (SRMF) between ions filled in A2 sites and Nb–O octahedron. Since the thermal properties of materials direct responding to the vibration of crystal lattices, the NTE change of CSBN crystals are considered as arising due to the geometry change for the different calcium-doped concentration. [Copyright &y& Elsevier]

Abstract: Passive mode-locking of a diode-pumped Nd:CLNGG laser was demonstrated for the first time to our knowledge. The laser operated at a central wavelength of 1061.2nm with a maximum average output power of 101mW. The mode-locked pulses have pulse duration of 2.0ps, a spectral bandwidth of 1.2nm and a repetition rate of 88.4MHz. The mode locking of the laser was enabled by a semiconductor saturable absorber mirror (SESAM). [Copyright &y& Elsevier]

Abstract: Passive mode-locking of a diode pumped Yb-doped GdVO4 crystal laser was demonstrated for the first time to our knowledge. The laser was mode-locked at the wavelength of 1019.1nm and had an average output power of 1.01W. The mode-locked pulse duration was 3.1ps. The laser was end-pumped by a high-power fiber pigtailed laser diode bar and the mode-locking was enabled by a semiconductor saturable absorber mirror (SESAM). [Copyright &y& Elsevier]

Annihilation of positronium (Ps) in static magnetic fields is investigated by positron annihilation lifetime (PAL) and Doppler broadening (DB) measurements of γ-Al 2 O 3 nanopowder. The properties of four eigenstates of Ps atoms (| 1,1 ⟩ , | 1 , − 1 ⟩ , | + ⟩ (long-lived eigenstate mixed from | 1,0 ⟩ and | 0,0 ⟩ due to Zeeman effect), and | − ⟩ (short-lived eigenstate mixed from | 1,0 ⟩ and | 0,0 ⟩ due to Zeeman effect)) were revealed from PAL and DB results. Thereafter, with magnetic field increasing from 0.105 to 0.760 T, clear and regular variation of Ps annihilation parameters are observed: (1) The mean lifetime of the three long-lived Ps states (| 1,1 ⟩ , | 1 , − 1 ⟩ , and | + ⟩) shows clear quenching effect; (2) The formation probability of each Ps eigenstate (| 1,1 ⟩ , | 1 , − 1 ⟩ , | + ⟩ , and | − ⟩) keeps unchanged; (3) The intensity of the narrow component (derived from multi-Gaussian fitting) of DB spectrum exhibits a gradual increase which is in good agreement with the theoretical calculation from PAL results (2γ decay of | + ⟩ and | − ⟩ states, and pick-off quenching of long-lived Ps states); (4) The intensity of the low energy region of DB spectrum is diminished by the decrease of 3γ decay of | + ⟩ state. The quantitative correlations between magnetic field and o-Ps annihilation parameters will be helpful for the further understanding of complex Ps quenching effects, such as the effect mixed from orhto-para spin conversion and magnetic quenching. • Magnetic quenching of positronium was investigated in nanometer-scaled porous γ-Al 2 O 3 which is very suitable for theformation of positronium. • Magnetic quenching of positronium was investigated by using both PAL and DB experimental techniques for the first time. • The multi-Gaussian fitting method was utilized to deduce the p-Ps intensity of each sample (the intensity of the narrowest component of each Doppler broadening spectrum). [ABSTRACT FROM AUTHOR]

Positron annihilation lifetime (PAL) spectroscopy is a unique technique to characterize atomic-scaled microstructure of materials, especially the vacancy-type defects. Compared to photomultiplier tube, silicon photomultiplier (SiPM) has a higher quantum efficiency, a more compact size, and a much lower price. Considering the evident advantages of SiPM, we developed a SiPM-based PAL (SiPM-PAL) spectrometer by using LFS-3 and LYSO scintillators in the sizes of 3 × 3 × l mm3. The performance of the SiPM-PAL spectrometer was studied with four different scintillator lengths (l) of 5.0, 9.5, 13.8, and 20.0 mm. Under the same experimental conditions, with LFS-3 scintillator length decreasing from 20.0 to 5.0 mm, the time resolution (in FWHM) of SiPM-PAL spectrometer was significantly improved from 174.9 to 135.9 ps. While for the SiPM-PAL spectrometer with LYSO scintillators, the time resolution improved from 181.9 to 137.0 ps with scintillator length decreasing from 20.0 to 5.0 mm. Compared to conventional PAL spectrometer using photomultiplier tubes, a novel, small size, and low cost PAL spectrometer is successfully constructed by using SiPMs. Easy customization and superiority in time resolution and small size of SiPM-based scintillation detectors guarantee high flexibility and adaptability to the SiPM-PAL spectrometers, positron micro-beam facilities, and angular correlation of positron annihilation radiation measurements. [ABSTRACT FROM AUTHOR]

Ag/SiO 2 /Si multilayer samples with different SiO 2 layer thicknesses were prepared through deposition of Ag layer onto SiO 2 /Si substrates at different substrate temperatures (T sub) by RF magnetron sputtering method. Microstructure of the multilayer was characterized by XRD θ /2 θ scan and φ -scan analysis, depth-resolved XPS analysis, and Doppler broadening of annihilation radiation (DBAR) spectra of positron measurements. The experimental results indicate that, at T sub = 25 °C, the Ag deposition forms Ag/SiO 2 /Si multilayer structure. With T sub increasing to 200 °C, Ag atoms are found to diffuse into the SiO 2 layer. This thermal diffusion process plays a critical role in removing SiO 2 layer on the Si substrate. At T sub of 600 °C, the 31-nm-thick SiO 2 layer is partially desorbed from the Si surface as a result of Ag diffusion, and eventually results in a deposition of Ag layer directly on the Si substrate. This is also confirmed by the XRD φ -scan measurements, which indicates epitaxial growth of Ag atoms directly on the surface of Si substrate at T sub of 600 °C. • The deposition of Ag on SiO 2 /Si substrate at 25 °C is easily forming Ag/SiO 2 /Si multilayer structure. • Compared with Ag single crystal, Ag films have the smaller positron effective diffusion lengths due to its higher density of structural defects. • Depth-resolved XPS results show the high diffusion nature of surface O when the substrate temperature up to 600 °C. [ABSTRACT FROM AUTHOR]

Examines allele diversities and haplotypes of two novel Y-STR in a Chinese population. Collection of EDTA-blood samples from unrelated males of Han population; Use of polymerase chain reaction (PCR) amplification; Genotyping of the PCR products.