Effect of Cooling Process on Microstructure and Properties of Low Carbon Bainite Steel

This article used Mn-Mo-Cr-B low-carbon bainitic steel as the experimental material. The continuous cooling transformation  curve of the steel during continuous cooling was determined using a Gleeble-1500D thermal simulation test machine, and a corresponding phase transformation model for bainitic steel during continuous cooling was established. The influence of different cooling rates and final cooling temperatures on the microstructure and mechanical properties of the steel was investigated. Employing metallography, SEM, and EBSD techniques, the microstructure, crystallographic orientation, and grain boundary angle distribution of the low-carbon bainitic steel were explored, and their relationship with the steel's strength and toughness was studied. The research findings reveal that varying cooling rates and final cooling temperatures impact the phase transformation process and microstructure of the steel, consequently affecting its mechanical properties indirectly. With increasing cooling rate, the diffusion and fineness of martensite increase, and the quantity of lath bainite grows while the laths become finer. Elevated final cooling temperatures lead to larger martensitic-austenitic (MA) islands and reduced lath bainite quantity, causing the laths to become wider. Through analysis of the substructure of bainitic steel, it was determined that the bainite organization in the tested steel comprises primary austenite grains, lath packet, and lath block in succession. Lath packets are composed of lath blocks with different orientations, where lath size predominantly controls strength. Finer lath size corresponds to higher strength, and the influence of substructure on toughness is comparatively minor

Categorical Properties of Soft Sets

The present study investigates some novel categorical properties of soft sets. By combining categorical theory with soft set theory, a categorical framework of soft set theory is established. It is proved that the category SFun of soft sets and soft functions has equalizers, finite products, pullbacks, and exponential properties. It is worth mentioning that we find that SFun is both a topological construct and Cartesian closed. The category SRel of soft sets and Z-soft set relations is also characterized, which shows the existence of the zero objects, biproducts, additive identities, injective objects, projective objects, injective hulls, and projective covers. Finally, by constructing proper adjoint situations, some intrinsic connections between SFun and SRel are established

Theoretical prediction of anisotropic in elasticity, density of states and thermodynamic properties of Ti–X (X = Fe, Co, Zn)

In this work, The mechanical properties, band structure, density of states and thermodynamic properties (at a temperature of 0–1200 K and a pressure of 0–40 GPa) of the Ti–X (X = Fe, Co, Zn) alloy are calculated by first-principles calculations based on density functional theory (DFT). The results show that the Ti–X (X = Fe, Co, Zn) alloy has mechanical stability and plasticity, and elasticity is anisotropic. By analyzing elastic anisotropy index ({\varvec{{A}}}^{\mathbf {U}}, {\varvec{{A}}}_{\mathbf {shera}}, {\varvec{{A}}}_{\mathbf {comp}}, {\varvec{{A}}}_{\mathbf {1}},{\varvec{{A}}}_{\mathbf {2}}, {\varvec{{A}}}_{\mathbf {3}}), 3D surface constructions and sound velocities, which shows that the elasticity and sound velocities of Ti–X (X = Fe, Co, Zn) alloy is anisotropic

Study of Electroless-Deposited Zn on the Surface of Mg-Li Alloy

The Mg-Li alloy stands as the lightest metallic structural material known to date, finding a wide range of applications. However, its development has been hindered by its susceptibility to oxidation and corrosion. In this study, we aimed to address this issue by employing electroless deposition to form a protective zinc layer on the surface of a magnesium–lithium alloy. The optimization of the zinc layer was achieved through varying parameters such as the zinc dipping time (1~10 min), temperature (20~70 °C), and zinc content (20~200 g/L). Surface characterization was performed using scanning electron microscopy (SEM) and X-ray diffraction, while electrochemical tests and scratch tests were conducted to evaluate corrosion resistance and coating adhesion. The results demonstrated the successful formation of a uniform and dense pure zinc layer on the surface of the Mg-Li alloy when the zinc-dipping time was set at 5 min, the temperature was at 30 °C, and the zinc content was at 50 g/L. Under these conditions, the corrosion potential of the Mg-Li alloy experienced the greatest positive shift, reaching as high as −1.38 V. Additionally, the corrosion current was minimized, measuring at 2.78 × 10−6 A/cm2. Furthermore, the maximum arc tolerance radius was observed. Consequently, the electroless deposition of zinc onto Mg-Li alloys significantly improves their corrosion resistance and bonding, opening up new prospects for the application of zinc-plated Mg-Li alloys

Decrease in Terahertz Conductivity of Graphene Under Electron Beam Irradiations

Electron beam (e-beam) irradiations are often involved for characterizing graphene-based terahertz (THz) devices or realizing graphene surface plasmons. Here, based on THz time-domain spectroscopy (TDS) and two-dimensional scanning system, the time dependence and the in situ mapping images of changed THz conductivity of graphene induced by e-beam irradiations are studied. The change in THz signals with irradiation indicates a decrease in the THz conductivity as a result of electron doping in graphene through irradiation. And the spatial imaging maps of the decreased THz conductivity reveal diverse electron doping speeds in graphene during different current e-beam irradiations. Additionally, different theoretical doping models are given for explanations of the imaging maps and the calculated results by doping models are in good accordance with the experimental results. Our findings are of significance for understanding the change in THz conductivity and carrier transport of graphene under e-beam irradiations

Efficacy and Safety of Pramipexole Sustained Release versus Immediate Release Formulation for Nocturnal Symptoms in Chinese Patients with Advanced Parkinson’s Disease: A Pilot Study

Objective. To explore the efficacy and safety of pramipexole sustained release (SR) versus pramipexole immediate release (IR) in treating nocturnal symptoms in levodopa-treated Chinese patients with advanced Parkinson’s disease (PD) and sleep disturbances. Method. SUSTAIN was an open-label, randomised, active-controlled parallel group exploratory pilot study (NCT03521635). A total of 98 patients were randomly allocated (1 : 1) to either pramipexole SR (n = 49) or pramipexole IR (n = 49) groups. The primary endpoint was a change from baseline in PD Sleep Scale 2nd version (PDSS-2) total score at 18 weeks. A reduction in score represents improvement. Secondary endpoints included Nocturnal Hypokinesia Questionnaire, Scales for Outcomes in PD Sleep Scale, Early Morning Off (EMO), Epworth Sleepiness Scale, PD Questionnaire-8, and responder rates as measured by PDSS-2 total score (<18), EMO scores (≥1 point change), Clinical Global Impression Improvement scale, and Patient Global Impression-Improvement scale. Other endpoints included motor complications (MDS-UPDRS part IV) score. Adverse events were evaluated for each group. Results. The mean pramipexole dose for both groups was 1.5 mg/day at week 18, and the mean changes in PDSS-2 total score for pramipexole SR and IR were –13.7 (95% CI –16.0 to –11.4) and –14.4 (–16.8 to –12.0) (difference of 0.7; p=0.688). Change from baseline for both groups achieved the minimal clinical important difference threshold (MCID = –3.44). No significant difference was observed in change from baseline for other measures of sleep-related disturbances or responder rates. For motor complications, a greater improvement in MDS-UPDRS part IV score was observed in pramipexole SR over IR (–3.4 vs –2.3; treatment group difference: –1.1; p=0.036). Both groups had comparable safety profiles. Conclusion. In Chinese patients with advanced PD and sleep disturbances, pramipexole SR and IR have similar benefits in the treatment of nocturnal symptoms and safety, and an improvement from baseline in nocturnal symptoms was observed regardless of pramipexole formulation

Direction controllable inverse transition radiation from the spatial dispersion in a graphene-dielectric stack

Transition radiation (TR) induced by electron-matter interaction usually demands vast accelerating voltages, and the radiation angle cannot be controlled. Here we present a mechanism of direction controllable inverse transition radiation (DCITR) in a graphene-dielectric stack excited by low-velocity electrons. The revealed mechanism shows that the induced hyperbolic-like spatial dispersion and the superposition of the individual bulk graphene plasmons (GPs) modes make the fields, which are supposed to be confined on the surface, radiate in the stack along a special radiation angle normal to the Poynting vector. By adjusting the chemical potential of the graphene sheets, the radiation angle can be controlled. And owing to the excitation of bulk GPs, only hundreds of volts for the accelerating voltage are required and the field intensity is dramatically enhanced compared with that of the normal TR. Furthermore, the presented mechanism can also be applied to the hyperbolic stack based on semiconductors in the infrared region as well as noble metals in the visible and ultraviolet region. Accordingly, the presented mechanism of DCITR is of great significance in particle detection, radiation emission, and so on