ABSTRACT
In order to synthesize a high-efficiency catalytic electrode for hydrogen evolution reactions, nano-MoS2 was deposited in situ on the surface of graphite substrates via a one-step hydrothermal method. The effects of the reactant concentration on the microstructure and the electrocatalytic characteristics of the nano-MoS2 catalyst layers were investigated in detail. The study results showed that nano-MoS2 sheets with a thickness of about 10 nm were successfully deposited on the surface of the graphite substrates. The reactant concentration had an important effect on uniform distribution of the catalyst layers. A higher or lower reactant concentration was disadvantageous for the electrochemical performance of the nano-MoS2 catalyst layers. The prepared electrode had the best electrocatalytic activity when the thiourea concentration was 0.10 mol·L-1. The minimum hydrogen evolution reaction overpotential was 196 mV (j = 10 mV·cm-2) and the corresponding Tafel slope was calculated to be 54.1 mV·dec-1. Moreover, the prepared electrode had an excellent cycling stability, and the microstructure and the electrocatalytic properties of the electrode had almost no change after 2000 cycles. The results of the present study are helpful for developing low-cost and efficient electrode material for hydrogen evolution reactions.
ABSTRACT
In this work, the Ti-20Zr-15Mo alloy in its hot-rolled state was annealed in different phase zones, and the effects of the annealing treatment on the phase composition, organization, mechanical and corrosion resistance properties of the alloy were systematically investigated. The results showed that the original ß grains of the alloy had all recrystallized to form the ß equiaxial grains when annealed at 800 °C, and the grains had been significantly refined. This allowed the alloy to reach a tensile strength of 1000 MPa, a maximum of 28% after stretching, and a significant increase in plasticity. Also, due to the single beta phase, there was no galvanic corrosion, making the alloy annealed at 800 °C have the best corrosion resistance.
ABSTRACT
The origin of ß-relaxation in metallic glasses is still not fully understood, and the guidance of slow atoms for caged dynamics and ß-relaxation is rarely mentioned. Using molecular dynamics simulations, we reveal the bridging role of slow atoms on unusual caged dynamics and ß-relaxation. In the stage of unusual caged dynamics, slow atoms are bounded by neighboring atoms. It is difficult for the slow atoms to break the cage, producing more high-frequency vibration, which causes more atoms to jump out of the cage randomly in the next stage. Precisely, the movement of the slow atoms changes from individual atoms vibrating inside the cage and gradually breaking out of the cage into a string-like pattern. The string-like collective atomic jumps cause decay of the cages, inducing ß-relaxation. This situation generally exists in binary systems with the large atomic mass difference. This work offers valuable insights for understanding the role of slow atoms in unusual caged dynamics and ß-relaxation, complementing studies on the origin of ß-relaxation in metallic glasses and their glass-forming liquids.
ABSTRACT
We report the formation of a sole long nanowire structure and the regular nanowire arrays inside a groove on the surface of Fe-based metallic glass upon irradiation of two temporally delayed femtosecond lasers with the identical linear polarization parallel and perpendicular to the groove, respectively. The regular structure formation can be well observed within the delay time of 20 ps for a given total laser fluence of F = 30 mJ/cm2 and within a total laser fluence range of F = 30-42 mJ/cm2 for a given delay time of 5 ps. The structural features, including the unit width and distribution period, are measured on a one-hundred nanometer scale, much less than the incident laser wavelength of 800 nm. The degree of structure regularity sharply contrasts with traditional observations. To comprehensively understand such phenomena, we propose a new physical model by considering the spin angular momentum of surface plasmon and its enhanced inhomogeneous magnetization for the ferromagnetic metal. Therefore, an intensive TE polarized magnetic surface wave is excited to result in the nanometer-scaled energy fringes and the ablative troughs. The theory is further verified by the observation of nanowire structure disappearance at the larger time delays of two laser pulses.
ABSTRACT
In this study, a novel photocatalyst composed of N-doped TiO2 (N-TiO2) and (Ca, Y)F2:Yb3+, Tm3+ was prepared by simple dealloying followed by a hydrothermal method. The composite exhibits a homogeneous nanoporous structure consisting of large quantities of the spindle-like N-doped TiO2 nanorods, on which the (Ca, Y)F2:Yb3+, Tm3+ particles with a diameter of around 5 nm are uniformly dispersed. In addition, morphology and property of the N-TiO2 can be controlled by adjusting the dealloying period. Results show that a short immersion time leads to a small size, large surface area and low band gap. As a result, the N-TiO2/(Ca, Y)F2:Yb3+, Tm3+ composite after dealloying for 48 h (TiO2-48-C) exhibits higher degradation rates (65.6% for 10 h irradiation by 980 nm NIR) than others after dealloying for 60 h (TiO2-60-C) and 72 h (TiO2-72-C), indicating its excellent potential for practical applications.
ABSTRACT
OBJECTIVE: To observe the effect of Dendrobium officinale granule (DOG) on symptoms, blood pressure and serum biochemical indexes of long-term-alcohol-induced hypertension rats. METHOD: The alcohol-induced hypertension rat model was established by feeding alcohol drink to normal rats (the alcohol volume fraction increases from 5% to 22%). Since the 4th week, DOG was administered for 32 weeks, once everyday. During the experiment, body weight, kinematic parameters (locomotor activities, grip strength, duration of vertigo) and blood pressures (systolic blood pressure, diastolic blood pressure and mean blood pressure) were detected regularly. On the 28th and 32nd weeks, blood samples were collected to determine serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), uric acid (UA), creatinine (Cr), cholesterol (CH) and triglycerides (TG). RESULT: (1) Sign: The DOG-administered group showed reduction in the duration of vertigo and increase in appetite, body weight, locomotor activities and grip strength. (2) Blood pressure: The DOG-administered group showed significant decrease in blood pressure since the 8th week. (3) Biochemical indexes: The DOG-administered group showed notable decrease in serum ALT, AST, ALP, Cr, UA, TG level, but without significant change in TC level. CONCLUSION: The long-term administration of DOG can relieve alcohol-induced hypertension, while alleviating general signs, liver and kidney injuries and abnormal blood fat biochemical indexes.
