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Sulfonated hyperbranched polyethersulfone (SHBPES)-modified halloysite nanotubes (HNTs), HNT-SHBPES, were synthesized and mixed with polyethersulfone (PES) to prepare hybrid ultrafiltration (UF) membranes via the phase inversion method. Pure PES and PES hybrid membranes mixed with SHBPES and HNTs were also prepared. The HNT-SHBPES showed good compatibility with the PES membrane matrix, and a series of PES/HNT-SHBPES hybrid membranes offered improved porosity, surface mean pore size, hydrophilicity, permeability, and anti-fouling properties. These were mainly attributed to the synergistic effects of hydrophilic -SO3H of SHBPES, porous HNTs, and the tiny interspace between HNT-SHBPES and PES matrix. When 8% HNT-SHBPES was doped into PES casting solution (MHS–8), its pure water flux reached 351.6 L/m2 h—this was nearly 2.2 times that of the pure PES membrane (M–0); its rejection rate remained high primarily due to the occurrence of delayed phase separation in the solidification process and the good compatibility between HNT-SHBPES and PES matrix. This resulted in a relatively dense, uniform, and defect-free surface. Additionally, bovine serum albumin (BSA) and humic acid (HA) were chosen as model contaminants to evaluate the anti-fouling properties of all prepared membranes. After multi-cycles UF experiments, MHS–8 retained a higher flux recovery rate and rejection rate than the other membranes confirming its excellent anti-fouling properties and stable overall performance. This work offers a new possibility for hyperbranched polymer-modified nanomaterials to enhance their compatibility with membrane matrix and improve membrane separation performance.

To develop colorless and soluble polyimide films, a novel dianhydride containing 1,4:3,6-dianhydro-D-mannitol unit, 2,5-bis(3,4-dicarboxyphenoxy)-1,4:3,6-dianhydromannitol dianhydride (IMDA) was synthesized. And two series of polyimides were prepared via a two-step thermal imidization, PI−(1–4) were obtained from IMDA and four kinds of aromatic diamines while PI−(5–7) from IMDA and three kinds of semiaromatic diamines. All the polyimides were readily soluble in common polar solvents and could afford flexible, tough and colorless films with transparency up to 89% at 450 nm. Especially, polyimides simultaneously containing 1,4:3,6-dianhydrohexitol units in diamine and dianhydride exhibited comparable optical and soluble performance with the alicyclic fluorinated ones. Meanwhile, it was certified that 1,4:3,6-dianhydrohexitol fragment in dianhydride was more determinant in solubility and transmittance of polyimides than that in diamine. An overall investigation of these polyimides on thermal, mechanical, morphological, soluble, optical and dielectric properties was presented, and their structure-property relationships were discussed in detail.

Titanium (Ti) decoration is considered as a promising strategy for preventing metallic uranium (U) surface from oxidization and corrosion. The O adsorption and diffusion behaviors on the clean and Ti-decorated γ-U(0 0 1) surfaces have been investigated by density functional theory (DFT) calculations in the present work. The preferred sites and stable configurations for O atoms on the surface and in the subsurface have been evaluated. It is found that O atoms tend to adsorb on the surface instead of absorbing in the subsurface. With nudged elastic band method, O atom on Ti-doped surfaces departs from the energetically favored site which there is a higher barrier than it on clean U surface. O and Ti can form a chemical bond of Ti-O, reducing the interaction of U and O, thereby enhancing the corrosion resistance of U surface.

In order to obtain colorless and soluble polyimide films, a dianhydride containing 1,4:3,6-dianhydro-d-mannitol unit, 2,5-bis(3,4-dicarboxyphenoxy)-1,4:3,6-dianhydromannitol dianhydride (IMDA) was synthesized. And a series of copolyimides were prepared from IMDA, 1,2,4,5-benzenetetracarboxylic anhydride (PMDA), and 4,4′-oxydianiline by adjusting the mole fraction (between IMDA and PMDA) of IMDA from 0% to 100%. It was found that the solubility as well as the transmittance of the copolyimide films enhanced with the increased content of IMDA. Especially, when the content of IMDA was 60% or more, the copolyimides were readily soluble in common polar solvents and could afford flexible, tough, and colorless films with transparency up to 84% at 450 nm, which may be ascribed to the incorporation of the relatively twisted and flexible 1,4:3,6-dianhydro-d-mannitol units into the backbone of copolyimides. Additionally, the influence of IMDA on the thermal, mechanical, and morphological properties of copolyimides was investigated.

The common neighbor analysis (CNA) for binary systems is a promising tool for the identification of chemical ordering in atomic configurations obtained from atomistic simulations. It is an extension of the monatomic CNA by taking the chemical species of common neighbors as an additional criterion and thus can give the individual short-range order for each atom and the long-range order for a block of atoms in binary alloys. The possible shortcoming is also obvious since they only reflect the characteristic arrangement of the nearest neighbors of the reference atom. Here we presented a further extension of the nearest-neighbor binary CNA method to the second-nearest neighbor one. The bulk signatures for the most common ordered structures based on face centered cubic were given, including D1/D7 (Ca7Ge/CuPt7), “40” (NbP), L10 (AuCu), L11 (CuPt), L12 (AuCu3), L13 (CuPt3), and D022 (Al3Ti). For these perfect bulk alloys, the extended binary CNA is able to correctly identify all the chemical ordered phases, while the original one fails except for the L11-structure. The types and magnitudes of ordered phases in several examples with some composition- and position-randomness and complexity are analyzed, including Ni/Ni3Al composite as well as Cu–Pt and Au–Pd nanoparticles obtained from off-lattice Monte Carlo simulations. It is demonstrated that this extended CNA method shows higher robustness and accuracy relative to the local mixing index or the polyhedral template matching scheme. The algorithm is implemented using Fortran programming language and the codes can be obtained by contacting the authors.

Lithium–iodine (Li–I2) batteries are considered a competitive candidate for next-generation electrochemical energy storage devices. The high solubility of I2 in aprotic solvents or aqueous solvent systems and the resulting shuttle effect can lead to the corrosion of metallic Li anodes. The present study employs atomistic scale modeling approaches to understand the interactions between Li surfaces and iodine species. It is found that the metallic Li (100) surface and Li (110) surface are very active to capture I2 molecules and facilitate the dissociation of these molecules. According to the ab initio molecular dynamics simulation, the iodization behavior is dependent on the coverage. When the iodine coverage is only 12.5%, the dissociated I atoms will not destroy the anode surface. As the coverage increases to 100%, a thin LiI layer forms but can be exfoliated from the Li surface, resulting in the irreversible loss of active materials. If the coverage is as high as 200%, a thick LiI film can form on the Li anode and deposit on the Li substrate. How the LiNO3 additive protects the Li–I2 battery anode is also studied in the present work. It is found that O and N atoms from the decomposition of the nitrate diffuse faster than I atoms in the metallic anode. Therefore, a Li oxynitride layer can form between the metallic Li metal and the iodine-containing species, which can cut off the direct interaction between the anode and I2 molecules.

Using Li2S as an active material and designing nanostructured cathode hosts are considered as promising strategies to improve the performance of lithium-sulfur (Li-S) batteries. In this study, the reaction mechanisms during the delithiation of nanoconfined Li2S as an active material, represented by a Li20S10 cluster, are examined by first-principles based calculations and analysis. Local reduction and disproportionation reactions can be observed although the overall delithiation process is an oxidation reaction. Long-chain polysulfides can form as intermediate products; however they may bind to insoluble S2-via Li atoms as mediators. Activating the charging process only requires an overpotential of 0.37 V if using Li20S10 as the active material. Sulfur allotropes longer than cyclo-S8 are observed at the end of the charge process. Although the discharge voltage of Li20S10 is only 1.27 V, it can still deliver an appreciable theoretical energy density of 1480 W h kg-1. This study also suggests that hole polarons, in Li20S10 and intermediate products, can serve as carriers to facilitate charge transport. This work provides new insights toward revealing the detailed reaction mechanisms of nanoconfined Li2S as an active material in the Li-S battery cathode.

Electrode host materials play a critical role in determining the electrochemical performance of the energy storage devices such as alkali metal-ion batteries. Cathode host materials are expected to provide good electronic and ionic conductivity, improved specific capacity and high discharge voltage. Two-dimensional (2D) transition metal dichalcogenides are competitive candidates as cathode materials due to their unique structure which can enhance ion diffusion and storage. In this study, a first-principles approach is used to investigate the H-ScO2 monolayer as the cathode host material for alkali metal-ion batteries. It is found that the H-ScO2 monolayer can deliver capacities of 348 mA h g−1, 348 mA h g−1 and 435 mA h g−1 for Li, Na and K storage, respectively, when the cutoff voltage of the discharge process is set to 1 V. During the discharge process, the averaged open circuit voltages are 4.15 V, 3.29 V and 2.89 V for Li-ion, Na-ion and K-ion batteries, respectively. The diffusion barriers of alkali metal atoms on the ScO2 monolayer are less than 0.43 eV. It can be inferred that the ScO2 monolayer is helpful for achieving high-voltage and high-capacity batteries with fast diffusion kinetics. Although the pristine H-ScO2 monolayer is a semiconductor, intermediate products during the discharge process always show half-metallic and metallic properties, which is also beneficial for increasing the electrical conductivity of the cathode.

Tungsten (W) and W-based alloys are competitive candidates for plasma-facing materials in future fusion reactors. W-tantalum (Ta) alloys get the most attention amongst these materials. The present study uses molecular dynamics simulations to study the displacement cascades of pure W and W-Ta alloy systems with recoil energy up to 100 keV at 300 K and the further evolution of cascade defects at 1,000 K. The effects of Ta concentration on the generation and evolution of the defects, produced with primary knock-on atom energies, are quantitatively analysed. This study's results show that the presence of randomly distributed Ta atoms does not significantly affect the average number of surviving Frenkel pairs or the fractions of clustered vacancies and interstitials. In addition, there is no completed vacancy dislocation loop in all systems after cascading. The produced dislocation loops are mainly 1/2 〈111〉 loops companied with a small amount of 〈100〉 loops and mixed loops. However, the existence of Ta atoms slows down the motion of defects and defect mobility decreases as the Ta concentration increases in bulk W. This will affect the size and density of defects. In addition, the presence of Ta also inhibits the transition of the 〈100〉 dislocation loops to 1/2 〈111〉 dislocation loops under the high-temperature condition. This will affect the types of dislocation loops and the material performance.

A novel hydrophilic polyamide, PA-OH containing 1:4;3:6-dianhydro-d-mannitol (isomannide) fragment was synthesized and used as an additive to prepare a series of polyethersulfone (PES)/PA-OH hybrid membranes with different content of PA-OH by phase separation method. And the addition of PA-OH was expected to improve the hydrophilicity, permeability, and antifouling performance of the PES ultrafiltration (UF) membrane. The scanning electron microscopic and atomic force microscopic images showed that the addition of PA-OH greatly changed the morphology of membranes by increasing the porosity, pore size and pore density, and the hydrophilicity was also improved with the increased PA-OH content. Based on the UF experiment, when the PA-OH content was 3%, the fluxes of pure water and bovine serum albumin solution reached 213.1 and 92.6 L m−2 h−1, which were close to 1.5 times and 2 times those of the bare PES membrane, respectively. When the PA-OH content was 5%, the FRR1st reached 85.2%, which was distinctly higher than that of the compared PES/polyethylene glycol5% hybrid membrane of 74.3%. And the FRR2st of the PES/PA-OH5% hybrid membrane was still over 80%, which indicated its long-term antifouling performance. Thus, the PA-OH can be a candidate for the hydrophilic additives.

Capacity fade in lithium-ion batteries largely originates from the undesired electrolyte decomposition, which results in the formation of solid electrolyte interphase (SEI) and the anode surface passivation. In this work, a mesoscale interfacial modeling approach is developed to investigate the formation and growth of the SEI film on a typical graphite based anode over several cycles. It is found that lithium diffusion kinetics in the SEI film significantly affects the SEI growth rate. A lower lithium diffusion barrier leads to a higher growth rate. The present model demonstrates that the SEI thickness is a linear function of the square root of the charging time over long-time cycling. Growth of multicomponent SEI film is also elucidated. It is found that the heterogeneity of the SEI film may lead to instability in lithium ion concentration distribution.

Molybdenum-rhenium alloys are usually used as the wall materials for high-temperature heat pipes using liquid sodium as heat-transfer medium. The corrosion of Mo in liquid Na is a key challenge for heat pipes. In addition, oxygen impurity also plays an important role in affecting the alloy resistance to Na liquid. In this article, the adsorption and diffusion behaviors of Na atom on Mo (110) surface are theoretically studied using first-principles approach, and the effects of alloy Re and impurity O atoms are investigated. The result shows that the Re alloy atom can strengthen the attractive interactions between Na/O and the Mo substrate, and the existence of Na or O atom on the Mo surface can slower down the Na diffusion by increasing diffusion barrier. The surface vacancy formation energy is also calculated. For the Mo (110) surface, the Na/O co-adsorption can lead to a low vacancy formation energy of 0.47 eV, which indicates the dissolution of Mo is a potential corrosion mechanism in the liquid Na environment with O impurities. It is worth noting that Re substitution atom can protect the Mo surface by increasing the vacancy formation energy to 1.06 eV.

Zn anodes suffer from poor Coulombic efficiency (CE) and serious dendrite formation due to the unstable anode/electrolyte interface (AEI). The electrical double layer (EDL) structure formed before cycling is of great significance for building stable solid electrolyte interphase (SEI) on Zn surface but barely discussed in previous research about the stabilization of Zn anode. Herein, saccharin (Sac) is introduced as electrolyte additive for regulating the EDL structure on the AEI. It is found that Sac derived anions are preferentially adsorbed on the Zn metal surface instead of water dipole, creating a new H2 O-poor EDL structure. Moreover, the unique SEI is also detected on the Zn surface due to the decomposition of Sac anions. Both are proved to be capable of modulating Zn deposition behavior and preventing side reactions. Encouragingly, Zn|Zn symmetric cells using Sac additive deliver a high cumulative plated capacity of 2.75 Ah cm-2 and a high average CE of 99.6% under harsh test condition (10 mA cm-2 , 10 mAh cm-2 ). The excellent stability is also achieved at a high rate of 40 mA cm-2 . The effectiveness of this Sac additive is further demonstrated in the Zn-MnO2 full cells.

The recently emerging renewable energy industry has boosted a research hot in searching for bifunctional electrocatalysts for water splitting. CoSe2, as one of transition-metal chalcogenides, has attracted particular attention because of its abundant resource, low cost, high efficiency and stability. However, further enhancing catalytic activity of CoSe2 to meet the large-scale application requirements of hydrogen energy remains an important challenge. Herein, three-dimension (3D) Mo-doped porous CoSe2 nanosheet array was directly formed on commercial Ni foam (Mo-CoSe2 NS@NF) electrode through a three-step process including electrodeposition, hydrothermal and subsequent selenylation. Systematically experimental research and density functional theory calculations confirmed that, based on active site and intermediate modulation effect of Mo doping, the obtained 3D Mo-CoSe2 NS@NF electrodes were provided with enlarged electrochemical active surface area, improved charge transport capability and significantly optimized binding energy for active intermediates of the potential-limiting step, thus exhibiting remarkably boosted bifunctional electrocatalytic ability with a low overpotential of 89 and 234 mV to drive a current density of 10 mA cm−2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media, respectively. When the Mo-CoSe2 NS@NF electrode was employed as both a cathode and an anode, an advanced water electrolyzer was fabricated, and a 10 mA cm−2 water splitting current density in 1 M KOH solution could be acquired at a minimal cell voltage of 1.54 V. In addition, we also inferred that the active surface for the OER was O* covered CoSe2, and OER occurred through direct recombination mechanism according to the present first-principles simulation. This work offers an atomistic understanding on the boosted HER and OER electrocatalytical activity of CoSe2 by Mo doping, and develops a promising strategy for exploring advanced low-cost and earth-abundant water splitting electrocatalysts to substitute for the precious-metallic catalysts as well.

Ni-rich layered lithium transition metal oxides LiNi x Mn y Co z O2 (1 – y – z ≥ 0.6) are promising candidates for cathode materials, but their practical applications are hindered by high-voltage instability and fast capacity fading. Using density functional theory calculations, we demonstrate that Na-, F-doping, and Na/F-co-doping can stabilize the structure and result into a higher open circuit voltage than pristine LiNi0.6Mn0.2Co0.2O2 (NMC622) during the charging process, which may attain greater discharge capacity. F doping may inhibit the diffusion of Li ions at the beginning and end of charging; Na doping may improve Li ion diffusion due to the increase in Li layer spacing, consistent with prior experiments. Na/F-co-doping into NMC622 promotes rate performance and reduces irreversible phase transitions for two reasons: (i) a synergistic effect between Na and F can effectively restrain the Ni/Li mixing and then enhances the mobility of Li ions and (ii) Ni/Li mixing hinders the Ni ions to migrate into Li layers and thus, stabilizes the structure. This study proposes that a layer cathode material with high electrochemical performance can be achieved via rational dopant modification, which is a promising strategy for designing efficient Li ion batteries.

The oxidation corrosion is a crucial challenge for zirconium (Zr) alloys as cladding materials in fission power reactors. In the present study, a first-principles approach is employed for understanding behaviors of oxygen adsorbed on the Zr ( 10 1 - 1 ) surface. It is found that the Zr substrate is reactive to O species. Electrons in the 4d band of the metallic substrate tend to migrate to antibonding orbitals of the adsorbed O2 molecule, leading to breaking the O-O bond and releasing energy. Several diffusion paths for an adsorbed O atom migrating to the subsurface interstitial site are proposed. It is found that the lowest diffusion barrier is only 0.08 eV. Therefore, it can be inferred that the Zr ( 10 1 - 1 ) surface suffers fast oxidation kinetics.

Nonaqueous Li-O2 and Na-O2 batteries are promising next-generation energy storage devices due to the outstanding energy density. Nevertheless, the current issue needed to be conquered is the sluggish electrochemical reactions, which can count on the choice of an active catalyst. This work theoretically investigates the two-dimensional (2D) double-layer honeycomb (DLHC) AlP as a cathode catalyst for Li-O2 and Na-O2 batteries. It is found that the DLHC AlP can lead to the O2 dissociation at the specific catalytic site with a low energy barrier. Different electrochemical reduction paths are proposed for understanding the discharge process. It is predicted that LiO2 and Li2O2 are the major products in Li-O2 batteries, and the discharge and charge overpotentials are predicted to be less than 0.68 V; while both NaO2 and Na2O2 are the possible products in Na-O2 batteries, and overpotentials are less than 0.27 V for charge and 0.43 V for discharge. The DLHC AlP can provide strong affinities to intermediate products, and the adsorption causes a local reversible phase transition with the formation of Al-O bonds. Our work suggests the DLHC AlP is a promising catalyst to promote energy efficiency for nonaqueous Li-O2 and Na-O2 batteries.

Background Nephrolithiasis is a common urinary disease with a high recurrence rate of secondary stone formation. Several mechanisms are involved in the onset and recurrence of nephrolithiasis, e.g., oxidative stress, inflammation, apoptosis, and epithelial-mesenchymal transition (EMT). Vitexin, a flavonoid monomer derived from medicinal plants that exert many biological effects including anti-inflammatory and anticancer effects, has not been investigated in nephrolithiasis studies. Moreover, pyroptosis, a form of programmed cell death resulting from inflammasome-associated caspase activation, has not been studied in mice with nephrolithiasis. Purpose We aimed to investigate the protective effect and underlying mechanisms of vitexin in nephrolithiasis, and the related role of pyroptosis in vivo and in vitro. Methods Mouse models of nephrolithiasis were established via intraperitoneal injection of glyoxylate, and cell models of tubular epithelial cells and macrophages were established using calcium oxalate monohydrate (COM). Crystal deposition and kidney tissue injury were evaluated by hematoxylin and eosin, and von Kossa staining. Renal oxidative stress indexes including malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and catalase (CAT), were analyzed. The renal expression of interleukin-1 beta (IL-1β), gasdermin D (GSDMD), osteopontin (OPN), CD44, and monocyte chemotactic protein 1 (MCP-1), and EMT-related proteins in renal tubular epithelial cells was assessed. Cell viability and the apoptosis ratio were evaluated. Results In vivo, vitexin alleviated crystal deposition and kidney tissue injury, and decreased the level of MDA, and increased the levels of SOD, GSH, and CAT. Vitexin also reduced the levels of the pyroptosis-related proteins GSDMD, NLRP3, cleaved caspase-1, and mature IL-1β, which were elevated in mice with nephrolithiasis, and repressed apoptosis and the expression of OPN and CD44. Moreover, vitexin mitigated F4/80-positive macrophage infiltration and MCP-1 expression in the kidneys. Furthermore, an in vitro study showed that vitexin increased the viability of HK-2 cells and THP-1-derived macrophages, which was impaired by treatment with COM crystals, decreased the medium lactate dehydrogenase (LDH) level, and inhibited the expression of pyroptosis-related proteins in HK-2 cells and macrophages. Vitexin repressed EMT of HK-2 cells, with increased expression of pan-cytokeratin (Pan-ck) and decreased expression of Vimentin and alpha-smooth muscle actin (α-SMA), and downregulated the Wnt/β-catenin pathway. Moreover, vitexin suppressed tumor necrosis factor-α (TNF-α) and IL-1β mRNA expression, which was upregulated by COM in macrophages. Conclusion Vitexin exerts protective effects against nephrolithiasis by inhibiting pyroptosis activation, apoptosis, EMT, and macrophage infiltration. In addition, GSDMD-related pyroptosis mediates nephrolithiasis.

Excessive sugar consumption could lead to high blood glucose levels that are harmful to mammalian health and life. Despite consuming large amounts of sugar‐rich food, fruit bats have a longer lifespan, raising the question of how these bats overcome potential hyperglycemia. We investigated the change of blood glucose level in nectar‐feeding bats (Eonycteris spelaea) and fruit‐eating bats (Cynopterus sphinx) via adjusting their sugar intake and time of flight. We found that the maximum blood glucose level of C. sphinx was higher than 24 mmol/L that is considered to be pathological in other mammals. After C. sphinx bats spent approximately 75% of their time to fly, their blood glucose levels dropped markedly, and the blood glucose of E. spelaea fell to the fast levels after they spent 70% time of fly. Thus, the level of blood glucose elevated with the quantity of sugar intake but declined with the time of flight. Our results indicate that high‐intensive flight is a key regulator for blood glucose homeostasis during foraging. High‐intensive flight may confer benefits to the fruit bats in foraging success and behavioral interactions and increases the efficiency of pollen and seed disposal mediated by bats.

Poor electronic conductivity of bulk lithium sulfide (Li2S) is a critical challenge for the debilitating performance of the lithium–sulfur battery. This study focuses on investigating the thermodynamic and kinetic properties of native defects in Li2S based on a first-principles approach. It is found that the hole polaron p+ can form in Li2S by removing a 3p electron from an S2– anion. The p+ diffusion barrier is only 90 meV, which is much lower than the Li vacancy (VLi–) diffusion barrier. Hence p+ has the potential to serve as a charge carrier in the discharge product. Once the vacancy–polaron complex (VLi––2p+) forms, the charge transport will be hindered due to the relatively higher diffusion barrier of the complex. Heteroatom dopants, which can decrease the p+ formation energy and increase VLi– formation energy, are expected to be introduced to the discharge product to improve the electronic conductivity.

Two-dimensional materials are competitive candidates as cathode materials in lithium–sulfur batteries for immobilizing soluble polysulfides and mitigating the shuttle effect. In this study, a mesoscale modeling approach, which combines first-principles simulation and kinetic Monte Carlo simulation, is employed to evaluate titanium silicide (Ti2Si and TiSi2) monolayers as potential host materials in lithium–sulfur batteries. It is found that the Ti2Si monolayer has much stronger affinities to Li2S x (x = 1, 2, 4) molecules than does the TiSi2 monolayer. Also, Ti2Si can facilitate the dissociation of long-chain Li2S4 to LiS2. On the other hand, TiSi2 can only provide a weak chemical interaction for trapping soluble Li2S4. Therefore, the Ti2Si monolayer can be considered to be the next-generation cathode material for lithium–sulfur batteries. Nevertheless, the strong interaction between Ti2Si and Li2S also causes fast surface passivation. How to control the Li2S precipitation on Ti2Si should be answered by future studies.

In this task, carboxylated polysulfone (PSF-COOH) was achieved by introducing the monomer of phenolphthalin (PPL) containing carboxyl to the molecule backbone of polysulfone (PSF). And a series of PSF-COOH copolymers with different carboxylation degree was synthesized by adjusting the molar (%) of bisphenol A (BPA) and PPL in direct copolymerization method and was prepared as PSF-COOH ultrafiltration membranes via phase separation method. The effect of PPL molar (%) in copolymers on the morphology, hydrophilicity, permeation flux, antifouling and mechanical properties of membranes was investigated by scanning electron microscope (SEM), atomic force microscope (AFM), water contact angle, ultrafiltration experiments and universal testing machine, respectively. The results showed that with the increased carboxyl content in membranes, the hydrophilicity, permeation fluxes and antifouling properties of membranes gradually increased. When the molar (%) of PPL to BPA was 100:0, the membrane exhibited the highest pure water flux (329.6 L/m 2 h) and the maximum flux recovery rate (92.5%). When the content of carboxyl in the membrane was 80% or more, after three cycles of BSA solution (1 g/L) filtration, the flux recovery rate was basically constant or showed a slightly increase. Thus, it can achieve the goal of long term usage without compromising flux.

Besides lithium sulfide (Li2S), lithium persulfide (Li2S2) is another solid discharge product in lithium–sulfur (Li–S) batteries. Revealing the charge transport mechanism in the discharge products is important for developing an effective strategy to improve the performance of Li–S batteries. Li2S2 cannot transport free electrons due to its wide bandgap between the valence band maximum (VBM) and conduction band minimum (CBM). However, electron polarons (p–) and hole polarons (p+) can appear in solid Li2S2 due to the unique molecular orbital structure of the S22– anion. The thermodynamic and kinetic properties of native defects are investigated. It is found that negatively charged Li vacancies (VLi–) and p+ are the main native defects with a low formation energy of 0.77 eV. The predominant charge carrier is p+ because p+ has a high mobility. The electronic conductivity related to p+ diffusion is dependent on temperature, and high temperatures are preferred to increase the conductivity.

The cathode surface passivation caused by Li2S precipitation adversely affects the performance of lithium–sulfur (Li–S) batteries. Li2S precipitation is a complicated mesoscale process involving adsorption, desorption and diffusion kinetics, which are affected profoundly by the reactant concentration and operating temperature. In this work, a mesoscale interfacial model is presented to study the growth of Li2S film on carbon cathode surface. Li2S film growth experiences nucleation, isolated Li2S island growth and island coalescence. The slow adsorption rate at small S2– concentration inhibits the formation of nucleation seeds and the lateral growth of Li2S islands, which deters surface passivation. An appropriate operating temperature, especially in the medium-to-high temperature range, can also defer surface passivation. Fewer Li2S nucleation seeds form in such an operating temperature range, thereby facilitating heterogeneous growth and potentially inhibiting the lateral growth of the Li2S film, which m...

As a widely used approach to modify a material's bulk properties, doping can effectively improve electrochemical properties and structural stability of various cathodes for rechargeable batteries, which usually empirically favors a uniform distribution of dopants. It is reported that dopant aggregation effectively boosts the cyclability of a Mg-doped P2-type layered cathode (Na0.67 Ni0.33 Mn0.67 O2 ). Experimental characterization and calculation consistently reveal that randomly distributed Mg dopants tend to segregate into the Na-layer during high-voltage cycling, leading to the formation of high-density precipitates. Intriguingly, such Mg-enriched precipitates, acting as 3D network pillars, can further enhance a material's mechanical strength, suppress cracking, and consequently benefit cyclability. This work not only deepens the understanding on dopant evolution but also offers a conceptually new approach by utilizing precipitation strengthening design to counter cracking related degradation and improve high-voltage cyclability of layered cathodes.

In this work, hydrogenated bisphenol A (HBPA) based dinitro mixed isomers (1a&prime, and 1a) were synthesized and separated via vacuum distillation under the monitor of DSC and 1H NMR. Corresponding diamines (2a&prime, and 2a) were separately polycondensed with five commercial dianhydrides via a two-step thermal imidization to obtain PI-(1&prime, 5&prime, ) and PI-(1-5). All the polyimides could afford flexible, tough, and transparent films, and most of them were readily soluble not only in common polar solvents like DMAc, but also in low boiling point solvents such as chloroform. 1H NMR spectra of the polyimides demonstrated that HBPA moiety showed no conformation changes during the preparation of polymers. For a given dianhydride, PI-(1-5) exhibited better thermal stability than that of PI-(1&prime, ), this can be attributed that the equatorial, equatorial C&ndash, O in PI-(1-5) promoted denser and more regular molecular chain stacking, as can be evidenced by the WAXD and geometric optimization results. Additionally, when the dianhydride was ODPA, BPADA or 6FDA, no apparent difference was found in either the transmittance or solubility between two series of polyimides, which could be attributed that twisted and flexible ether linkages, as well as bulky substituents, led to the &ldquo, already weakened&rdquo, inter- and intramolecular CT interaction and cohesive force. However, when it came to rigid and stiff dianhydride, e.g., BPDA, PI-3&prime, took an obvious advantage over PI-3 in transmittance and solubility, which was possibly owed to the larger molecular chain d-spacing imparted by equatorial, axial C&ndash, O. An overall investigation of PI-(1&prime, ) and PI-(1-5) on aspects of thermal, mechanical, morphological, soluble and optical performance values was carried out, and the conformation effects of HBPA isomers on the properties of two series of polyimides were discussed in detail.

In this work, hydrogenated bisphenol A (HBPA) based dinitro mixed isomers (1a′ and 1a) were synthesized and separated via vacuum distillation under the monitor of DSC and 1H NMR. Corresponding diamines (2a′ and 2a) were separately polycondensed with five commercial dianhydrides via a two-step thermal imidization to obtain PI-(1′-5′) and PI-(1-5). All the polyimides could afford flexible, tough, and transparent films, and most of them were readily soluble not only in common polar solvents like DMAc, but also in low boiling point solvents such as chloroform. 1H NMR spectra of the polyimides demonstrated that HBPA moiety showed no conformation changes during the preparation of polymers. For a given dianhydride, PI-(1-5) exhibited better thermal stability than that of PI-(1′-5′), this can be attributed that the equatorial, equatorial C–O in PI-(1-5) promoted denser and more regular molecular chain stacking, as can be evidenced by the WAXD and geometric optimization results. Additionally, when the dianhydride was ODPA, BPADA or 6FDA, no apparent difference was found in either the transmittance or solubility between two series of polyimides, which could be attributed that twisted and flexible ether linkages, as well as bulky substituents, led to the “already weakened” inter- and intramolecular CT interaction and cohesive force. However, when it came to rigid and stiff dianhydride, e.g., BPDA, PI-3′ took an obvious advantage over PI-3 in transmittance and solubility, which was possibly owed to the larger molecular chain d-spacing imparted by equatorial, axial C–O. An overall investigation of PI-(1′-5′) and PI-(1-5) on aspects of thermal, mechanical, morphological, soluble and optical performance values was carried out, and the conformation effects of HBPA isomers on the properties of two series of polyimides were discussed in detail.

The polysulfide shuttle phenomenon substantially deteriorates the electrochemical performance of lithium-sulfur (Li-S) batteries, resulting in continued self-discharge and capacity fade during cycling. In this study, a mesoscale analysis is presented to explore the mechanisms of self-discharge behavior in the Li-S battery during the resting state. It is found that the self-discharge rate is determined by the sulfur solubility, desorption capability, diffusion kinetics, and reaction rate on the anode surface. Three regimes have been identified: desorption control, diffusion control, and charge transfer control. Correspondingly, strategies are suggested to increase the capacity retention, such as enhancing the binding of sulfur molecules to the host, reducing dissolved sulfur diffusivity, and improving the chemical stability of active materials with a Li metal anode. Furthermore, the use of an interlayer with high diffusion barriers can effectively suppress the self-discharge rate due to the confinement effect.

Land leeches in the family Haemadipsidae are mostly from the humid tropical rainforest habitats and habitually take blood from the body of human and other animals. In the present study, we report a new species, Sinospelaeobdella wulingensis sp. n., from caves in the northern subtropical Wuling Mountains of central-south China that feeds blood exclusively on cave-dwelling bats. Based on morphological characteristics, COI gene sequence divergence, and phylogenetic analysis, a new genus Sinospelaeobdella gen. n. is established for the new species, to which a previously described species Haemadipsa cavatuses Yang et al., 2009 is transferred as S. cavatuses comb. n. We also provided extended discussion on phylogenetic relationship within the “Tritetrabdellinae” clade uncovered in a previous study, DNA taxonomy, morphological and behavioral adaptions, biogeography, and possible involvement of Sinospelaeobdella gen. n. in bat transmitted diseases of public concerns.

The sodium-selenium (Na-Se) battery is a competitive candidate as the practical next-generation energy storage device. A Na16Se8 cluster confined within a (10, 10) single-walled carbon nanotube is constructed to reveal the nanoconfinement effect on the reaction mechanism of the Na-Se battery cathode. It is found that the nanoconfinement can enhance the electronic conductivity of Na x≥12Se8 nanostructures because itinerant electrons appear under this condition. During desodiation, polyselenide chains grow longer and the intermediate products become insulators for transferring electrons. However, hole polarons have the potential to act as charge carriers in Na x≤10Se8 nanostructures. The open-circuit voltage profile is plotted, and the voltage window is 1.67 ≤ U ≤ 1 V. After the first charge cycle, the cathode cannot discharge to Na16Se8, but the reversible specific capacity can still arrive at 302 mA h/g of the cathode composite.

Habitat selection by the Chinese horseshoe bat (Rhinolophus sinicus) in the Wuling Mountains was studied in this paper. Global positioning system (GPS), remote sensing (RS) and geographic information system (GIS) technologies were used to obtain ground survey data and analyse the habitat factors driving the distribution of R. sinicus. Based on these basic data, a binary logistic regression method was used to establish habitat selection models of R. sinicus. Then, the corrected Akaike information criterion (AICC) was used to screen an optimal model, and the Hosmer-Lemeshow test indicated that the optimal model has suitable goodness of fit. Finally, the optimal model was used to predict the spatial distribution of R. sinicus in the Wuling Mountains. Verification analysis showed that the overall accuracy of the model was 72.7% and that the area under the curve (AUC) value was 0.947, which indicated that the model was effective for predicting suitable habitat for R. sinicus. The model results also showed that the main factors that influenced habitat selection were slope, annual mean temperature and distances from roads, rivers and residential land. R. sinicus preferred areas far from roads and residential land and areas near rivers. Generally, higher values of slope and annual mean temperature were associated with a greater likelihood of R. sinicus presence. Therefore, the protection of the water bodies surrounding R. sinicus habitats and fully addressing the impacts of human activities on R. sinicus habitats are recommended to protect the survival and reproduction of the population.

Nanofiltration (NF) membrane typically prepared by interfacial polymerization (IP) technology is facing the problems of low permeance and flux-selectivity trade-off effect, which will seriously affect the efficiency of water purification. Here, novel NF membranes with a thin and crumpled polyamide (PA) layer were obtained by introducing low concentration of soluble inorganic salts (≤2 wt%) in the IP process and thermally induced crystallization of inorganic salts in the heat treatment process. The forces generated by the growth of inorganic salt crystals inevitably stretched the nascent and flexible PA layer, and further the inorganic salt crystals can sacrifice themselves in water, contributing to the formation of a thin and rough PA layer with crumpled nanostructure. Using NaCl as an example, the resulting NF membrane exhibited the permeation flux as high as 84 L/m2 h at 4 bar while maintaining a high rejection of 96.2% for Na2SO4. Meanwhile, it is universal for other soluble inorganic salts such as KCl, Na2SO4, KNO3 and CaCl2 to improve the filtration performance of NF membrane. This study is the first to combine the growth of inorganic salt crystals with the morphology regulation of PA active layer in the heat treatment process, which will further expand the research method of NF membrane with efficient water purification.

Fe–Cr–Al alloys have the potential to form a crucial class of enhanced accident tolerant fuel cladding materials in light water reactor due to their excellent oxidation resistance in high temperature steam environments. The irradiation resistant performance is also significant for the development and application of fission and fusion reactor materials. In this work, we developed a Fe–Cr–Al interatomic potential based on the Finnis–Sinclair (F–S) formulism, which can be used to describe the defect properties in Fe–Cr–Al alloys. The potential parameters for Fe–Cr–Al alloys were determined by fitting to a set of experimental results and density functional theory (DFT) calculations. Specifically, the formation energies of self–interstitial atoms and the stacking fault energy obtained from the present Al potential are consistent with the DFT results. The point–defect properties of Fe–Cr and Fe–Al alloys determined with the DFT calculations, such as the mixed (both Fe–Cr and Fe–Al) or pure (both Cr–Cr and Al–Al) dumbbells and the substitutions (both Cr and Al atoms) in the body–centered cubic (bcc) Fe matrix, are well reproduced by our atomistic simulations. Consequently, this parameterized potential is expected to be capable for atomistic simulations of irradiation defects and defect evolution in Fe–Cr–Al ternary systems.

Zirconium (Zr) alloys as cladding materials are widely used in fission reactors. The service life of Zr-based materials cladding is seriously affected by the hydrogen (H) behaviors; while the impurities (C, N and O) in Zr alloys have a great influence on the hydrogen behaviors. In this work, we have investigated the impurity–hydrogen interactions in hexagonal-closed packed Zr (hcp-Zr) by a first-principles approach. It was found that H atom tends to occupy tetrahedral interstitial position in perfect Zr and occupy octahedral interstitial position in Zr with vacancy, while the impurities tend to occupy octahedral interstitial positions in Zr both with and without vacancy. The impurities can trap H atoms. Four possible paths were studied for the diffusion of H atom in hcp-Zr, and it is found that the diffusion barriers of H varied with the presence of impurities.

Transition metal oxides are usually used as catalysts in the air cathode of lithium-air (Li-air) batteries. This study elucidates the mechanistic origin of the oxygen reduction reaction catalyzed by δ-MnO2 monolayers and maps the conditions for Li2O2 growth using a combination of first-principles calculations and mesoscale modeling. The MnO2 monolayer, in the absence of an applied potential, preferentially reacts with a Li atom instead of an O2 molecule to initiate the formation of LiO2. The oxygen reduction products (LiO2, Li2O2, and Li2O molecules) strongly interact with the MnO2 monolayer via the stabilization of Li-O chemical bonds with lattice oxygen atoms. As compared to the disproportionation reaction, direct lithiation reactions are the primary contributors to the stabilization of Li2O2 on the MnO2 monolayer. The energy profiles of (Li2O2)2 and (Li2O)2 nucleation on δ-MnO2 monolayer during the discharge process demonstrate that Li2O2 is the predominant discharge product and that further reduction to Li2O is inhibited by the high overpotential of 1.21 V. Interface structures have been examined to study the interaction between the Li2O2 and MnO2 layers. This study demonstrates that a Li2O2 film can be homogeneously deposited onto δ-MnO2 and that the Li2O2/MnO2 interface acts as an electrical conductor. A mesoscale model, developed based on findings from the first-principles calculations, further shows that Li2O2 is the primary product of electrochemical reactions when the applied potential is smaller than 2.4 V.

A hybrid inversion method was developed to estimate the leaf chlorophyll content LCC and canopy chlorophyll content CCC of crops. Fifty hyperspectral vegetation indices VIs, such as the photochemical reflectance index PRI and canopy chlorophyll index CCI, were compared to identify the appropriate VIs for crop LCC and CCC inversion. The hybrid inversion models were then generated from different modelling methods, including the curve-fitting and least squares support vector regression LS-SVR and random forest regression RFR algorithms, by using simulated Compact High Resolution Imaging Spectrometer CHRIS datasets that were generated by a radiative transfer model. Finally, the remote-sensing mapping of a CHRIS image was completed to test the inversion accuracy. The results showed that the remote-sensing mapping of the CHRIS image yielded an accuracy of R2 = 0.77 and normalized root mean squared error NRMSE = 17.34% for the CCC inversion, and an accuracy of only R2 = 0.33 and NRMSE = 26.03% for LCC inversion, which indicates that the remote-sensing technique was more appropriate for obtaining chlorophyll content at the canopy scale CCC than at the leaf scale LCC. The estimated results of various VIs and algorithms suggested that the PRI and CCI were the optimal VIs for LCC and CCC inversion, respectively, and RFR was the optimal method for modelling.

The internal shuttle effect caused by polysulfides dissolution and migration negatively impacts lithium–sulfur battery performance. In this work, a mesoscale simulation strategy, which involves atomistic calculation and coarse-grained molecular modeling, is employed to evaluate silicene as a potential cathode host material to immobilize polysulfides. Adsorption energies of insoluble polysulfides (Li2Sx with x = 1, 2) and soluble polysulfide Li2S4 on pristine and doped silicene sheets are calculated. Results show that the adsorption is thermodynamically favorable and N-doped silicene is helpful in trapping intermediate discharge products, Li2S2 and Li2S4. The dissociation and reduction of long-chain polysulfides to short-chain polysulfides are observed. Electronic structure analysis shows that Li2Sx molecules interact with silicene via strong chemical bonds. The atomistic structure evolution of Li2S layer formation on silicene is also investigated in this study. It is found that Li2S (110) layer ...

Embedding the fragmented selenium into the micropores of carbon host has been regarded as an effective strategy to change the Li-Se chemistry by a solid-solid mechanism, thereby enabling an excellent cycling stability in Li-Se batteries using carbonate electrolyte. However, the effect of spatial confinement by micropores in the electrochemical behavior of carbon/selenium materials remains ambiguous. A comparative study of using both microporous (MiC) and mesoporous carbons (MeC) with narrow pore size distribution as selenium hosts is herein reported. Systematic investigations reveal that the high Se utilization rate and better electrode kinetics of MiC/Se cathode than MeC/Se cathode may originate from both its improved Li+ and electronic conductivities. The small pore size (

Optimizing the activity of layered molybdenum disulfide (MoS2) toward hydrogen evolution reaction (HER) process is generally achieved by improving the electrical transport, intrinsic activity, and/or the number of active sites. However, simultaneously coupling these factors to achieve remarkable MoS2-based electrocatalysts has been seldom reported. Herein, we report a facile approach to the defect-rich one-dimensional MoS2 hierarchical architecture (1D-DRHA MoS2), which synergistically integrate the advantageous structural features of rich defects and one-dimensional hierarchal morphology. Toward HER process, the 1D-DRHA MoS2 electrocatalyst exhibited an overpotential of 119 mV at 10 mA cm−2, a Tafel slope of 50.7 mV dec-1, accompanied by an excellent stability. Notably, the activity is competitive to the state-of-the-art MoS2-based electrocatalysts for HER. The combination of experimental evidences and density functional theory calculations demonstrated the incorporation of rich defects and one-dimensional hierarchical structure improved electric conductivity, intrinsic activity, and active sites, which together accounted for the boosted HER performance.

Our previous study (J. Mater. Chem. A, 2018, 6, 3171-3180) theoretically predicted that a scandium oxide (ScO2) monolayer can deliver high specific capacity and energy density as the active material of a lithium-ion (Li-ion) battery, but the voltage will drop below 0.5 V when ScO2 is lithiated to LiScO2 during the discharge process. The current study predicts that the discharge product LiScO2 in the Li-ion battery mode can potentially work as the host material of Li-O2 batteries. It is found that the adsorption of O2 on the LiScO2 substrate is energetically favored. The LiScO2 substrate can also provide strong affinities to molecular LiO2 and Li2O2 species. It is interesting to find that the presence of an O2 molecule can oxidize the pre-adsorbed Li2O2 molecule and result in two LiO2 molecules. Hence, the final discharge product of the Li-O2 battery using the LiScO2 cathode is expected to be a crystalline-like LiO2 layer. The discharge voltage related to forming a LiO2 layer on the LiScO2 substrate is 3.50 V vs. Li+/Li according to the present theoretical calculation.

In this study, ferrous-oxalate(FeC2O4)-decorated polyphenylene sulfide(PPS) catalytic microfiber(PPS/FeC2O4) was synthesized as an efficient heterogeneous Fenton catalyst through a chemical precipitation method. Moreover, an underlying mechanism of synthetic processes was investigated and verified by monitoring intermediate products. Regarding the mechanism, the catalytic microfiber was found to solidly anchor FeC2O4 crystal grains on the surface due to sulfonated PPS interface bonding, remarkably improving the operational stability and reusability of the PPS/FeC2O4 catalyst. Additionally, the separation process of PPS/FeC2O4 was simplified without time-consuming filtration, attributable to the tangled structure of non-woven fabric that prevented the fibers from dispersing. In the typical process, improvement in the PPS/FeC2O4 catalyst revealed methylene blue degradation efficiency of the catalytic fiber above 90% at 6 min and 99% at 15 min, superior to that of the FeC2O4 catalyst. Therefore, PPS/FeC2O4 can be utilized as a potential heterogeneous Fenton catalyst for organic contaminant degradation in wastewater.

Using Li

Supplemental Material, Supporting_information for Novel copolyimides containing 1,4:3,6-dianhydro-d-mannitol unit Preparation, characterization, thermal, mechanical, soluble, and optical properties by Zhiming Mi, Zhixiao Liu, Chunbo Wang, Tao Wang, Zhao Zhang, Daming Wang, Xiaogang Zhao, Hongwei Zhou, Yumin Zhang, and Chunhai Chen in High Performance Polymers

The shuttle effect and poor conductivity of the discharge products are among the primary impediments and scientific challenges for lithium–sulfur batteries. The lithium–sulfur battery is a complex energy storage system, which involves multistep electrochemical reactions, insoluble polysulfide precipitation in the cathode, soluble polysulfide transport, and self-discharge caused by chemical reactions between polysulfides and Li metal anode. These phenomena happen at different length and time-scales and are difficult to be entirely gauged by experimental techniques. In this paper, we reviewed the multiscale modeling studies on lithium–sulfur batteries: (1) the atomistic simulations were employed to seek alternative materials for mitigating the shuttle effect; (2) the growth kinetics of Li2S film and corresponding surface passivation were investigated by the interfacial model based on findings from atomistic simulations; (3) the nature of Li2S2, which is the only solid intermediate product, was revealed by the density functional theory simulation; and (4) macroscale models were developed to analyze the effect of reaction kinetics, sulfur loading, and transport properties on the cell performance. The challenge for the multiscale modeling approach is translating the microscopic information from atomistic simulations and interfacial model into the meso-/macroscale model for accurately predicting the cell performance.

Li intercalation and diffusion in pristine and modified SnS2 interlayer are studied by a first-principles approach. The results predict that the octahedral interstitial site is energetically favored for Li intercalation. The minimum energy path of Li diffusion in SnS2 interlayer is investigated by climbing image nudged elastic band method. It is found that Li atom diffuses from one energetically favored octahedral interstitial site to the neighbor one via tetrahedral interstitial site. The expansion of interlayer spacing is beneficial for decreasing the diffusion barrier. Ce dopant negatively impacts the Li diffusivity although it can optimize the interlayer spacing. Geometric structures of LixSnS2 (0x ≤ 3) are investigated to understand the lithiation-induced volume expansion and atomic structure change. The lithiation process can be divided into two stages. When Li content (x in LixSnS2) is less than 1, the volume expansion is not dramatic and only S atoms capture electrons from Li atoms. When Li content is larger than 1, Sn(4+) cations are significantly reduced, S-Sn-S trilayer gradually decomposes, and LixS2 (1 ≤ x ≤ 3) layer forms between two Sn monolayers. The mechanism of volume expansion is elucidated in this study.

Titanium (Ti) film is experimentally used to provide good protection for uranium (U) surface from corrosion, but the performance of the protector is limited by the strength of the Ti/U interface. Therefore, it is important to further understand the interaction between Ti atoms and U surfaces. Here the first-principles density functional theory approaches with spin polarization and non-spin polarization have been employed to study the stability and diffusion properties of Ti atoms on α-uranium (0 0 1) and (1 0 0) surfaces. The energetic, geometric parameters and electronic structures have been analyzed. For Ti/U(0 0 1) surface, it is found that the most energetically favoured configuration is Ti atom occupying the hollow2 site. Ti atom tends to diffuse from hollow1 site to hollow2 site via the longbridge site. The U–Ti bond is dominated by the hybridization between Ti 3d and U 5f states, and the negative charge is transferred to the first U layer from the adsorbed Ti atom. For Ti/U(1 0 0) surface, the hollow site is the most preferred site for the adsorption of Ti atom. Ti atom will overcome a low barrier of ∼0.2 eV when it diffuses from one hollow site to another via the longbridge site. The topmost two U layers get electrons from Ti atom and the deeper U layers.