High-entropy alloys (HEAs) have become a topic of high research interest due to the excellent mechanical properties that can be found in this new type of materials. However, their functional ...properties are usually modest when compared to conventional materials. The discovery of high-entropy alloys with an optimal combination of mechanical and functional properties would be a leap forward in the reliability of devices that use them as functional elements. This Research Update focuses on magnetocaloric HEAs, showing that a directed search strategy allows us to improve their performance in a significant way, closing the pre-existing gap between magnetocaloric HEAs and high-performance magnetocaloric materials. Further challenges that remain in this line of research are highlighted.
Aqueous lithium-ion batteries may solve the safety problem associated with lithium-ion batteries that use highly toxic and flammable organic solvents, and the poor cycling life associated with ...commercialized aqueous rechargeable batteries such as lead-acid and nickel-metal hydride systems. But all reported aqueous lithium-ion battery systems have shown poor stability: the capacity retention is typically less than 50% after 100 cycles. Here, the stability of electrode materials in an aqueous electrolyte was extensively analysed. The negative electrodes of aqueous lithium-ion batteries in a discharged state can react with water and oxygen, resulting in capacity fading upon cycling. By eliminating oxygen, adjusting the pH values of the electrolyte and using carbon-coated electrode materials, LiTi(2)(PO(4))(3)/Li(2)SO(4)/LiFePO(4) aqueous lithium-ion batteries exhibited excellent stability with capacity retention over 90% after 1,000 cycles when being fully charged/discharged in 10 minutes and 85% after 50 cycles even at a very low current rate of 8 hours for a full charge/discharge offering an energy storage system with high safety, low cost, long cycling life and appropriate energy density.
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•Cryogenic temperature increases yield and ultimate strength of reinforcements.•Cryogenic temperature reduces the ductility of the reinforcing steels.•The failure of reinforcing steel ...changes from ductile to brittle mode at −80°C.•Proposed equations predict well the strength of steel at cryogenic temperature.
The increasing demands of the liquid natural gas (LNG) container and engineering constructions in the cold regions require the reinforcing steels could work under the cryogenic temperatures. This paper reported the experimental studies on the mechanical properties of HRB335, HRB400, and SLTS type of reinforcing steels that were used in the reinforced concrete structures and LNG containers. A test program consisted of 63 steel coupons was performed under different cryogenic temperatures ranging from −165°C to 20°C. The test results revealed the influences of the cryogenic temperatures on the mechanical properties of the different reinforcing steels that included stress-strain behaviours, elastic Young’s modulus, yield and ultimate strength, fracture strain, and percentage of reduction in the cross sectional area. Discussions were also made on the differences of the influences of the cryogenic temperatures on the mechanical properties among different types of reinforcing steels. Based on the test results, empirical design equations were developed through the regression analysis on the reported test results. The accuracies of these developed equations were checked through validations of the predictions against the test results. Conclusions and design recommendations were made based on these experimental and analytical studies.
Batting an in-flight object to the target Jia, Yan-Bin; Gardner, Matthew; Mu, Xiaoqian
The International journal of robotics research,
04/2019, Letnik:
38, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Striking a flying object such as a ball to some target location is a highly skillful maneuver that a human being has to learn through a great deal of practice. In robotic manipulation, precision ...batting remains one of the most challenging tasks in which computer vision, modeling, planning, control, and action must be tightly coordinated in a split second. This paper investigates the problem of a two-degree-of-freedom robotic arm intercepting an object in free flight and redirecting it to some target with a single strike, assuming all the movements take place in one vertical plane. Two-dimensional impact is solved under Coulomb friction and energy-based restitution with a proof of termination. Planning combines impact dynamics and projectile flight mechanics with manipulator kinematics and image-based motion estimation. As the object is on the incoming flight, the post-impact task constraint of reaching the target is propagated backward in time, while the arm’s kinematic constraints are propagated forward (via joint trajectory interpolation), all to the pre-impact instant when they will meet constraints that allow batting to happen. All the constraints (16 in total) are then exerted on the arm’s pre-impact joint angles and velocities, which are repeatedly planned based on updated estimates of the object’s motion captured by a high-speed camera. The arm keeps adjusting its motion in sync with planning until batting takes place. Experiments have demonstrated a better batting performance by a Barrett Technology WAM Arm than by a human being without training.
A series of bifunctional phase-transfer catalysts with a quaternary onium center and a hydrogen-bonding donor group were prepared for the fixation of CO2 with commercially available epoxides under ...mild conditions by using a CO2 balloon (1 atm). In the presence of 2.5 mol% of achiral bifunctional phase-transfer catalysts, cyclic carbonates were obtained in good to excellent yields (up to 95%). Additionally, optical carbonates and epoxides were obtained through the kinetic resolution of rac-epoxides by 1 mol% of chiral bifunctional phase-transfer catalysts with low enantioselectivities. These catalysts featured a simple synthetic route, good modularity and high efficiency.
Gold nanoparticles,owing to their unique physicochemical and optical properties,well-established synthetic methods and easy modifications,have been widely used in biomedical science.Therefore,for ...their safe and efficient applications,much attention has been given to the toxicological evaluations of gold nanoparticles in biological systems.A large number of studies focusing on this problem have been carried out during the past years.However,the researches on gold nanoparticles toxicity still remain fragmentary and even contradictory with each other.This may be caused by the variety in experimental conditions.In this review,we aim to provide a better understanding about the in vitro and in vivo toxicity of gold nanoparticles by reviewing and describing the up to date literatures related to this problem and we mainly focused on these properties such as the particle size and shape,the surface charge and modification.Besides,we also summarized the adverse effect of gold nanoparticles on immune systems and analyzed the origin of the toxicity.
Ferroptosis, a new non-necrotizing programmed cell death (PCD), is driven by iron-dependent phospholipid peroxidation. Ferroptosis plays a key role in secondary traumatic brain injury and secondary ...spinal cord injury and is closely related to inflammation, immunity, and chronic injuries. The inhibitors against ferroptosis effectively improve iron homeostasis, lipid metabolism, redox stabilization, neuronal remodeling, and functional recovery after trauma. In this review, we elaborate on the latest molecular mechanisms of ferroptosis, emphasize its role in secondary central nervous trauma, and update the medicines used to suppress ferroptosis following injuries.
Nod-like receptor protein 3 (NLRP3)-associated neuroinflammation mediated by activated microglia is involved in the pathogenesis of depression. The role of the pore-forming protein gasdermin D ...(GSDMD), a newly identified pyroptosis executioner downstream of NLRP3 inflammasome mediating inflammatory programmed cell death, in depression has not been well defined. Here, we provide evidence that paeoniflorin (PF), a monoterpene glycoside compound derived from
Paeonia lactiflora
, ameliorated reserpine-induced mouse depression-like behaviors, characterized as increased mobility time in tail suspension test and forced swimming test, as well as the abnormal alteration of synaptic plasticity in the depressive hippocampus. The molecular docking simulation predicted that PF would interact with C-terminus of GSDMD. We further demonstrated that PF administration inhibited the enhanced expression of GSDMD which mainly distributed in microglia, along with the proteins involved in pyroptosis signaling transduction including caspase (CASP)-11, CASP-1, NLRP3, and interleukin (IL)-1β in the hippocampus of mice treated with reserpine. And also, PF prevented lipopolysaccharide (LPS) and adenosine triphosphate (ATP)-induced pyroptosis in murine N9 microglia in vitro, evidenced by inhibiting the expression of CASP-11, NLRP3, CASP-1 cleavage, as well as IL-1β. Furthermore, VX-765, an effective and selective inhibitor for CASP-1 activation, reduced the expression of inflammasome and pyroptosis-associated proteins in over-activated N9 and also facilitated PF-mediated inhibition of pyroptosis synergistically. Collectively, the data indicated that PF exerted antidepressant effects, alleviating neuroinflammation through inhibiting CASP-11-dependent pyroptosis signaling transduction induced by over-activated microglia in the hippocampus of mice treated with reserpine. Thus, GSDMD-mediated pyroptosis in activated microglia is a previously unrecognized inflammatory mechanism of depression and represents a unique therapeutic opportunity for mitigating depression given PF administration.
GroupqV monochalcogenides are emerging as a new class of layered materials beyond graphene, transition metal dichalcogenides （TMDCs）, and black phosphorus （BP）. In this paper, we report experimental ...and theoretical investigations of the band structure and transport properties of GeSe and its heterostructures. We find that GeSe exhibits a markedly anisotropic electronic transport, with maximum conductance along the armchair direction. Density functional theory calculations reveal that the effective mass is 2.7 times larger along the zigzag direction than the armchair direction; this mass anisotropy explains the observed anisotropic conductance. The crystallographic orientation of GeSe is confirmed by angle- resolved polarized Raman measurements, which are further supported by calculated Raman tensors for the orthorhombic structure. Novel GeSeflVIoS2 p-n heterojunctions are fabricated, combining the natural p-type doping in GeSe and n-type doping in MoS2. The temperature dependence of the measured junction current reveals that GeSe and MoS2 have a type-II band alignment with a conduction band offset of N 0.234 eV. The anisotropic conductance of GeSe may enable the development of new electronic and optoelectronic devices, such as high-efficiency thermoelectric devices and plasmonic devices with resonance frequency continuously tunable through light polarization direction. The unique GeSe/MoS2 p-n junctions with type-II alignment may become essential building blocks of vertical tunneling field-effect transistors for low-power applications. The novel p-type layered material GeSe can also be combined with n-type TMDCs to form heterogeneous complementary metal oxide semiconductor （CMOS） circuits.
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