Optimal design of gears contact interface modification for an objective as minimum impact resistance of initial meshing-in time domain

Meccanica - In gear pair actual alternating meshing process, the comprehensive errors of the transmission system and the thermal elastic deformation of the teeth body cause the gears in the meshing...     

Alkaline oxygen evolution: exploring synergy between fcc and hcp cobalt nanoparticles entrapped in N-doped graphene

Herein, we report a Mott-Schottky catalyst by entrapping cobalt nanoparticles inside the N-doped graphene shell (Co@NC). The Co@NC delivered excellent oxygen evolution activity with an overpotential of merely 248 mV at a current density of 10 mA cm^–2 with promising long-term stability. The importance of Co encapsulated in NC has further been demonstrated by synthesizing Co nanoparticles without NC shell. The synergy between the hexagonal close-packed (hcp) and face-centered cubic (fcc) Co plays a major role to improve the OER activity, whereas the NC shell optimizes the electronic structure, improves the electron conductivity, and offers a large number of active sites in Co@NC. The density functional theory calculations have revealed that the hcp Co has a dominant role in the surface reaction of electrocatalytic oxygen evolution, whereas the fcc phase induces the built-in electric field at the interfaces with N-doped graphene to accelerate the H⁺ ion transport.     

Direct Synthesis of Adipic Esters and Adiponitrile via Photoassisted Cobalt-Catalyzed Alkene Hydrodimerization

The direct hydrodimerization of acrylates and acrylonitrile offers a general streamlined access to industrially important intermediates to nylon 6,6. However, a practical catalytic method for this process has thus far underdeveloped owing to the challenges in regioselectivity and environmental compatibility of applied reagents. Here, we report a cobalt-catalyzed tail-to-tail hydrodimerization of activated alkenes driven by a visible-light photoredox catalysis at ambient temperature, which is applicable to both adipates and adiponitrile synthesis from potentially renewable feedstocks. This protocol utilizes half equivalent of hantzsch ester as a recyclable two-electron and two-proton donor with the assistance of catalytic amount of base as a proton shuttle, and has been shown to be highly regioselective and efficient for hydrodimerizing various activated alkenes to 1,4-difunctionalized butane derivatives.     

Acridone-Based Host Materials for Green Phosphorescent and Thermally Activated Delayed Fluorescent OLEDs with Low-Efficiency Roll-Offs

By linking the carbazole unit to the nitrogen atom of acridone through phenyl or pyridyl, two compounds, named 10-(4-(9H-carbazol-9-yl)phenyl)acridin-9(10H)-one (AC-Ph-Cz) and 10-(5-(9H-carbazol-9-yl)pyridin-2-yl)acridin-9(10H)-one (AC-Py-Cz) were designed and synthesized. These two materials, characterized with highly twisted and rigid structure, good thermal stability, and balanced carrier-transporting properties, were employed as host materials for green phosphorescent and thermally activated delayed fluorescent organic light-emitting diodes (OLEDs). The carbazole group, despite its small contribution to the highest occupied molecular orbitals (HOMOs) of these two materials, plays an essential role as an intramolecular host in energy delivering and improving the hole transporting ability of these two hosts. The incorporation of the electron-deficient pyridyl group as a linking group slightly improves the electron transporting capability of AC-Py-Cz. The green phosphorescent OLED (PhOLED) based on AC-Py-Cz exhibited excellent device performance with a turn-on voltage of 2.5 V, a maximum power efficiency and an external quantum efficiency (η_ext) of 89.8 lm W⁻¹ and 25.2 %, respectively, benefitting from the better charge-balancing ability of AC-Py-Cz host due to the presence of the pyridyl bridge. More importantly, all the devices based on these two hosts showed low efficiency roll-off at high brightness due to the suppressed non-radiative transition in the emitting layer. In particular, the AC-Py-Cz-hosted green PhOLED exhibited an efficiency roll-off of 1.6 % from the maximum next at a high brightness of 1000 cd m⁻² and a roll-off of 15.9 % at an extremely high brightness of 10000 cd m⁻². This study manifests that acridone-based host materials have great potential in fabricating OLEDs with low efficiency roll-off.     

A review of recent advances in catalytic combustion of VOCs on perovskite-type catalysts

Along with the rapid development of industry, VOCs gradually move into the spotlight, and now become a kind of harmful environmental pollutants that cannot be overlooked. This paper introduces the hazards of VOCs and the common catalytic combustion catalysts, noble metal catalysts and non-noble metal catalysts, for the elimination of VOCs. Perovskite catalysts, as one of the non-noble catalysts, play an important role in the field of catalytic combustion in recent years. According to the classification of elements doping in perovskites, the research achievements in the past five years were analyzed and reviewed. In addition, this paper also analyzes and elaborates the reaction kinetics and QSAR/QSPR models for the introduction of structural properties and reaction mechanisms.     

Influence of inherent alkali metal chlorides on pyrolysis mechanism of a lignin model dimer based on DFT study

Journal of Thermal Analysis and Calorimetry - In order to understand the catalytic effects of inherent inorganic elements in biomass on the pyrolysis mechanism of lignin, density functional theory...     

Thermal behaviour of glazed ceramic bodies

Journal of Thermal Analysis and Calorimetry - Flower-shaped Ni-doped Fe3O4/SnS2 composite was synthesized by a one-pot solvothermal method, where nanosized Ni-doped Fe3O4 particles were dispersed...     

An improved evaluation of the neutron background in the PandaX-Ⅱ experiment

In dark matter direct detection experiments,neutron is a serious source of background,which can mimic the dark matter-nucleus scattering signals.In this paper,we present an improved evaluation of the neutron background in the PandaX-II dark matter experiment by a novel approach.Instead of fully relying on the Monte Carlo simulation,the overall neutron background is determined from the neutron-induced high energy signals in the data.In addition,the probability of producing a dark-matter-like background per neutron is evaluated with a complete Monte Carlo generator,where the correlated emission of neutron(s)andγ(s)in the(α,n)reactions and spontaneous fissions is taken into consideration.With this method,the neutron backgrounds in the Run 9(26-ton-day)and Run 10(28-ton-day)data sets of PandaX-II are estimated to be(0.66±0.24)and(0.47±0.25)events,respectively.