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Unsymmetrical dimethylhydrazine (UDMH), as a high-energy liquid propellant, is widely used in aerospace, rocket, aircraft, and other fields. However, it also has certain toxicity, fire, and explosion risks, which will cause harm to the human liver, kidney, central nervous system, blood system, etc., especially the nervous system. UDMH is easy to be adsorbed on the surface of the human body or other substances, but there is a lack of research reports on the measurement of its adsorption capacity. In this paper, based on the principle of measuring gas adsorption capacity by the volumetric method, a set of UDMH gas adsorption capacity testing devices was built. In the experiment, 304 and 316L stainless steel materials were used as the adsorbent. Under the same experimental temperature and pressure conditions, the test bottle containing the adsorbent was filled with UDMH gas of different concentrations and fully adsorbed until saturation to explore the influence of 304 stainless steel surface roughness and 304 and 316L stainless steel materials on the adsorption capacity of UDMH gas under the same experimental conditions. The experimental results show that the adsorption capacity of 304 and 316L stainless steel materials to UDMH gas increases with the increase of UDMH gas concentration in the concentration range (0~100 ppm) studied in this paper. After polishing the surface of 304 stainless steel material, compared with the unpolished 304 stainless steel material under the same conditions, the adsorption capacity after polishing is significantly smaller, indicating that the larger the surface roughness of the adsorbent, the more adsorption capacity. Under the same conditions, the adsorption capacity of UDMH gas on 304 and 316L stainless steel materials is approximately equal. The experiment also proves that the adsorption of UDMH gas on stainless steel materials conforms to monolayer adsorption within the concentration range studied in this paper.

The generation and propagation characteristics of bright spatial bound-soliton pairs (BSPs) are investigated under the diffusion effect in photovoltaic photorefractive crystals by numerical simulation. The results show that two coherent solitons, one as the signal light and the other as the control light, can form a BSP when the peak intensity of the control light is appropriately selected. Moreover, under the diffusion effect, the BSP experiences a self-bending process during propagating and the center of the BSP moves on a parabolic trajectory. Furthermore, the lateral shift of the BSP at the output face of the crystal can be manipulated by adjusting the peak intensity of the control light. The research results provide a method for the design of all-optical switching and routing based on the manipulation of the lateral position of BSPs.

A spatio-temporal mode-locked (STML) fiber laser is reported based on a semiconductor saturable absorber mirror. The laser has an all-fiber structure and the mode-locking threshold is as low as 200 mW. Single and multiple pulses with switchable central wavelengths are obtained. In particular, pump hysteresis is observed during the generation and disappearance of multiple pulses. The experimental results help to further understand the dynamic characteristics of STML fiber lasers and to explore how they are connected with conventional mode-locked fiber lasers in terms of soliton nonlinear phenomena, which may stimulate new applications in optical communications and nonlinear science.

Ultrafast fiber lasers have been demonstrated to be great platforms for the investigation of soliton dynamics. The soliton molecules, as one of the most fascinating nonlinear phenomena, have been a hot topic in the field of nonlinear optics in recent years. Herein, we experimentally observed the real-time evolving behavior of soliton molecule in an ultrafast fiber laser by using the dispersive Fourier transformation technology. Several types of evolving soliton molecules were obtained in our experiments, such as soliton molecules with monotonically or chaotically evolving phase, flipping and hopping phase. These results would be helpful to the communities interested in soliton nonlinear dynamics as well as ultrafast laser technologies.

The electronic, optical and thermodynamic properties of ZnS in the zinc-blende (ZB) and wurtzite (WZ) structures are investigated by using the plane-wave pseudopotential density functional theory (DFT). The results obtained are consistent with other theoretical results and the available experimental data. When the pressures are above 20.5 and 27 GPa, the ZB-ZnS and the WZ-ZnS are converted into indirect gap semiconductors, respectively. The critical point structure of the frequency-dependent complex dielectric function is investigated and analysed to identify the optical transitions. Moreover, the values of heat capacity CV and Debye temperature ? at different pressures and different temperatures are also obtained successfully.

The pressure dependence of elastic properties of ZnS in zinc-blende (ZB) and wurtzite (WZ) structures are investigated by the generalized gradient approximation (GGA) within the plane-wave pseudopotential density functional theory (DFT). Our results are in good agreement with the available experimental data and other theoretical results. From the high-pressure elastic constants obtained, we find that the ZB and WZ structures of ZnS are unstable when the applied pressures are larger than 15.8 GPa and 21.3 GPa, respectively. The sound velocities along different directions for the two structures are also obtained. It is shown that as pressure increases, the sound velocities of the shear wave decrease, and those of all the longitudinal waves increase. An analysis has been made to reveal the anisotropy and highly noncentral forces in ZnS.

The pressure induced phase transition of ZnS from the wurtzite (WZ) and the zincblende (ZB) structures to the rocksalt (RS) structure and the temperature induced phase transition from the ZB structure to the WZ structure axe investigated by ab initio plane-wave pseudopotential density-functional theory (I)FT), together with the quasi-harmonic Debye model. It is found that the zero-temperature transition pressures from the WZ-ZnS and the ZB-ZnS to the RS-ZnS are 17.20 and 17.37 GPa, respectively. The zero-pressure transition temperature from the ZB-ZnS to the WZ-ZnS is 1199 K. All these results are consistent with the available experimental data. Moreover, the dependences of the normalized primitive cell volume V/V-0 on pressure and thermal expansion coefficient alpha on temperature are also obtained successfully.

The phase transition and melting curves of CaF2 are investigated by using the general utility lattice programme (GULP) via the shell model with molecular dynamics method. By calculating the entropy H (at 0K) and Gibbs free energy G ⁄ (at 300K), we flnd that the phase transition pressure from the face-centred cubic (fcc) structure to the orthorhombic structure is 11.40GPa and 9.33GPa at 0K and 300K, respectively. The modifled melting point of the fcc CaF2 is in the range of 1650{1733K at 0GPa. All these results are well consistent with the available experimental data and other theoretical results. We also obtain that the melting temperature of high pressure phase is 990{1073K at 10GPa. Moreover, the temperature dependences of the elastic constants Cij, bulk module B and shear module G are also predicted.

The influence of an optically induced waveguide lattice with a defect on the coherent interaction of one-dimensional lattice solitons (LSs) formed via the photovoltaic photorefractive effect is investigated by employing numerical simulations. The results show that the uniform lattice can keep the neighboring LSs propagating with constant spacing and can affect the energy transfer between them. Further research has shown that the energy transfer can be effectively controlled by adjusting the relative phase difference between neighboring LSs and by introducing a defect in the waveguide lattice.