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Lithium-sulfur (Li–S) batteries have received widespread attention for the reason that their specific capacity is dramatically higher than that of current lithium-ion batteries. However, Li–S batteries still have problems such as poor conductivity, severe "shuttle effect", huge volume changes in the cathode, and lithium dendrites. Here, we report the introduction of carbon nanotubes (CNTs) into metal-organic frameworks (MOFs)-Cu-BTC and obtained Cu-BTC/CNTs with a three-dimensional structure by hydrothermal method. This structure solves the problem of inefficient electrochemical performance caused by poor conductivity when using Cu-BTC to adsorb lithium polysulfides (LiPSs). At the same time, the abundant porous structure is capable of effectively alleviating the volume expansion of the cathode during the reaction process. More importantly, Cu-BTC/CNTs catalyzes redox reactions, greatly improves the catalytic effect of Cu-BTC on LiPSs and the utilization of sulfur. As a result, The Cu-BTC/CNTs/S as sulfur host in the Li–S batteries cathode delivers an initial discharge of 924.69 mAh/g at 0.2C. Even at a high rate of 1C, it also exhibits a specific capacity of 805.28 mAh/g and still maintains 406.68mAh/g after 200 cycles at 1C. The above results indicate that the introduction of CNTs not only improves the overall conductivity of the material but also can fully exert the catalytic effect of Cu-BTC on the conversion of LiPSs. This work provides a convenient strategy to promote the conversion of LiPSs along with improving the catalytic activity of MOFs in Li–S batteries. [ABSTRACT FROM AUTHOR]

Fine particulate matter (PM2.5) has been linked to increased severity and incidence of airway diseases, especially chronic obstructive pulmonary disease (COPD) and asthma. Airway remodeling is an important event in both COPD and asthma, and airway smooth muscle cells (ASMCs) are key cells which directly involved in airway remodeling. However, it was unclear how PM2.5 affected ASMCs. This study investigates the effects of PM2.5 on airway smooth muscle and its mechanism. We first showed that inhaled particulate matter was distributed in the airway smooth muscle bundle, combined with increased airway smooth muscle bundle and collagen deposition in vivo. Then, we demonstrated that PM2.5 induced up-regulation of collagen-I and alpha-smooth muscle actin (α-SMA) expression in rat and human ASMCs in vitro. Next, we found PM2.5 led to rat and human ASMCs senescence and exhibited senescence-associated secretory phenotype (SASP) by autophagy-induced GATA4/TRAF6/NF-κB signaling, which contributed to collagen-I and α-SMA synthesis as well as airway smooth muscle remodeling. Together, our results provided evidence that SASP induced by PM2.5 in airway smooth muscle cells prompted airway remodeling. [Display omitted] • Inhaled particular matter induced airway smooth muscle remodeling. • PM2.5 led to ASMCs senescence and exhibited senescence-associated secretory phenotype (SASP). • SASP contributed to collagen-I and α-SMA synthesis as well as airway smooth muscle remodeling. • Inhibition of SASP prevented PM2.5-induced airway remodeling. [ABSTRACT FROM AUTHOR]

Metal lenticular gaskets have been widely applied in the bolt flange joints of high and ultrahigh pressure pipelines due to their semi-self-tightening sealing properties. However, research on the leakage prediction of the metal lenticular gaskets is still lacking, which limits their further optimal design and sealing performance improvement. In this paper, an elastoplastic contact mechanics analysis of a metal lenticular gasket used in the bolted flange joint of ultra-high pressure polyethylene pipelines was firstly carried out. The analytical formulas of contact stress and contact width were derived and compared with corresponding numerical results. Then, based on the surface topography measurement, a leakage model was established, in which the pipe surface was simplified to a smooth rigid flat surface, and the gasket surface was simplified to an equivalent rough surface composed of identical wedges. Finally, an analytical leakage prediction formula for the metal lenticular gasket was proposed. In addition, the effects of influence factors on leakage rate were discussed. It is shown that the analytical formulas can accurately calculate the contact stress and contact width in elastoplastic contact. The leakage rate increases with the decrease of the bolt load and the increase of internal pressure. For the ultrahigh pressure pipeline with internal pressure of 200 MPa, the minimum bolt load should be ensured to be higher than 120 kN in order to meet the T5 tightness level. In addition, the initial contact diameter is basically proportional to the leakage rate, while the change of gasket inclination angle has little effect on the leakage rate. Therefore, the contact diameter can be designed to be as small as possible within a reasonable range. This work can provide a theoretical basis for the sealing optimal design of metal lenticular gaskets. • An elastoplastic contact mechanics analysis of lenticular gasket used in ultra-high pressure (UHP) seal was carried out. • The theoretical formulas of contact stress and contact width were derived and verified by numerical simulations. • A leakage prediction formula of the UHP gaskets associated with contact mechanics and gasket parameters was derived. • The factors affecting leakage rates are discussed, which provided a theoretical basis for research of UHP seal. [ABSTRACT FROM AUTHOR]

Activation of ionotropic P2X receptors increases free intracellular Ca2+ ([Ca2+]i) by initiating a transmembrane cation flux. We studied the "a" and "k" splice variants of the rat purinergic P2X7 receptor (rP2X7aR and rP2X7kR) to exhibit a significant difference in Ca2+ flux through this channel. This difference is surprising because the variants share absolute sequence identity in the area of the pore that defines ionic selectivity. Here, we used patch-clamp fluorometry and chimeric receptors to show that the fraction of the total current carried by Ca2+ is a function of the primary sequence of the cytoplasmic N terminus. Using scanning mutagenesis, we identified five sites within the N terminus that respond to mutagenesis with a decrease in fractional calcium current and an increase in permeability to the polyatomic cation, N-methyl-D-glucamine (NMDG), relative to Na (PNMDG/PNa). We tested the hypothesis that these sites line the permeation pathway by measuring the ability of thiol-reactive MTSET to alter the current of cysteine-substituted variants, but we detected no effect. Finally, we studied the homologous sites of the rat P2X2 receptor (rP2X2R) and observed that substitutions at Glu17 significantly reduced the fractional calcium current. Taken together, our results suggest that a change in the structure of the N terminus alters the ability of an intra-pore Ca2+ selectivity filter to discriminate among permeating cations. These results are noteworthy for two reasons: they identify a previously unknown outcome of mutagenesis of the N-terminal domain, and they suggest caution when assigning structure to function for truncated P2X receptors that lack a part of the N terminus. [ABSTRACT FROM AUTHOR]

The Isochronous Mass Spectrometry (IMS) is a powerful tool for mass measurements of exotic nuclei with half-lives as short as several tens of micro-seconds in storage rings. In order to improve the mass resolving power while preserving the acceptance of the storage ring, the IMS with two Time-Of-Flight (TOF) detectors has been implemented at the storage ring CSRe in Lanzhou, China. Additional velocity information beside the revolution time in the ring can be obtained for each of the stored ions by using the double TOF detector system. In this paper, we introduced a new method of using a 658 nm laser range finder and a short-pulsed ultra-violet laser to directly measure the distance and time delay difference between the two TOF detectors which were installed inside the 1 0 − 11 mbar vacuum chambers. The results showed that the distance between the two ultra-thin carbon foils of the two TOF detectors was ranging from 18032.5 mm to 18035.0 mm over a measurable area of 20 × 20 mm 2. Given the measured distance, the time delay difference which comes with signal cable length difference between the two TOF detectors was measured to be Δ t d e l a y 1 − 2 = 99 (26) ps. The new method has enabled us to use the speed of light in vacuum to calibrate the velocity of stored ions in the ring. The velocity resolution of the current double TOF detector system at CSRe was deduced to be σ (v) ∕ v = 4. 4 × 1 0 − 4 for laser light, mainly limited by the time resolution of the TOF detectors. [ABSTRACT FROM AUTHOR]

The superb mechanical properties make graphene an ideal candidate material for impact protection. Combining molecular dynamics simulations and theoretical analyses, the deformation and failure modes, energy absorption of single-layer graphene under ballistic impact are investigated. According to numerical and theoretical results, the expression for residual velocity of projectile after impact is given. The dependence of deformation and failure modes, energy absorption mechanisms, specific penetration energy (SPE) on impact velocity is analyzed. The results show that during low-velocity impact, there are conical deformation region (CDR), star-like crack and monoatomic carbon chain in graphene. Energy absorption mechanisms of graphene are mainly local deformation and fracture. With increasing impact velocity, the size of CDR decreases. The star-like crack gradually transforms into circular hole. When impact velocity is high enough, carbon atoms within projectile projection area in graphene will be ejected in the form of debris. The kinetic energy (KE) loss of projectile is converted into KE of debris carbon atoms and fracture energy of carbon bonds. Besides, it is also found that SPE (dominant factors are deformation of conical region and KE increments) exhibits a decreasing–increasing trend with increasing impact velocity. When impact velocity is the same, SPE decreases with increasing projectile diameter. [Display omitted] • Energy absorption of graphene under ballistic impact is studied by MD simulations. • The expression for residual velocity of rigid projectile after impact is given. • The dependence of deformation and failure modes on impact velocity is discussed. • Energy absorption mechanism of graphene during impact process is analyzed. • The effect of impact velocity on specific penetration energy is studied. [ABSTRACT FROM AUTHOR]

The coastal zone, an ecotone that provides vital diverse ecosystem services, is one of the most ecologically fragile and sensitive areas on the Earth. It has been strongly influenced by human activities and climate change. Thus, understanding the spatiotemporal changes of land use land cover in the coast is an essential prerequisite for the comprehensive evaluation of coastal ecosystems and the promotion of sustainable development. This study investigated the spatial and temporal changes of land use land cover in the coastal zone of mainland Shanghai by using high spatial resolution aerial images, and the associated driving factors obtained from statistical yearbooks between 1989 and 2015. Our results show that the total land area in the coastal zone exhibited an increasing trend at an annual rate of 7.6% on average. The coastal urban land use also experienced substantial increases, with the degree of urban expansion reaching 42.1% in 2015. The coastal urbanization was at the cost of natural and semi-natural lands. Nearly 64.4% of agricultural land, 24.4% of ocean area within the buffer, 84.9% of fresh water, and 92.8% of the tidal flat had been converted to urban land during 1989–2015. The gradient analysis of land use land cover change along the north-to-south coastal line revealed the spatiotemporal patterns of total land, urbanization degree, and natural and semi-natural lands. The majority of the socioeconomic factors influenced land use land cover change in the coastal zone, positively contributing to the increase of public facilities' use of land, but negatively affecting the freshwater areas. These findings can provide insights for decision-making in the future for coastal land use land cover planning and management in Shanghai. • Total land area in coastal zone exhibited an increasing trend from 1985 to 2015. • Coastal urbanization in Shanghai reached 42.1% at the end of 2015. • Rapid urbanization in the coastal zone was at the cost of natural and semi-natural lands. • Gradient analysis revealed the spatiotemporal patterns of land use changes. • Socioeconomic factors drove the land use land cover change in the coastal zone. [ABSTRACT FROM AUTHOR]