Soluble and Perfluorinated Polyelectrolyte for Safe and High-Performance Li-O2 Batteries.

The severe performance degradation of high-capacity Li-O2 batteries induced by Li dendrite growth and concentration polarization from the low Li+ transfer number of conventional electrolytes hinder their practical applications. Herein, lithiated Nafion (LN) with the sulfonic group immobilized on the perfluorinated backbone has been designed as a soluble lithium salt for preparing a less flammable polyelectrolyte solution, which not only simultaneously achieves a high Li+ transfer number (0.84) and conductivity (2.5 mS cm-1 ), but also the perfluorinated anion of LN produces a LiF-rich SEI for protecting the Li anode from dendrite growth. Thus, the Li-O2 battery with a LN-based electrolyte achieves an all-round performance improvement, like low charge overpotential (0.18 V), large discharge capacity (9508 mAh g-1 ), and excellent cycling performance (225 cycles). Besides, the fabricated pouch-type Li-air cells exhibit promising applications to power electronic equipment with satisfactory safety.

Tuning the catalytic activity of a single Mo atom supported on graphene for nitrogen reduction via Se atom doping.

Electrochemical nitrogen (N2) fixation as an effective method has realized the sustainable production of ammonia where efficient electrocatalysts for converting N2 into NH3 at room temperature have become a key scientific issue. Herein, we proposed that the catalytic activity of a single Mo atom supported on graphene (Mo/G) for the nitrogen reduction reaction (NRR) can be tuned by non-metal heteroatom (B, N, P, S, Se etc.) doping. Our density functional theory (DFT) calculations revealed that the Se atom is the best doping element to tune the optimal electronic structure of the Mo atom for catalyzing the NRR among these heteroatoms, leading to the lowest potential of 0.41 V vs. RHE for Mo/SeG, which is much better than the current metal-based catalysts. Our work provided a new strategy to design electrocatalysts for the NRR.

An Integrated Design with new Metal-Functionalized Covalent Organic Frameworks for the Effective Electroreduction of CO2.

One of the long-standing issues that prohibits large-scale CO2 reutilization is the low aqueous solubility of CO2 and the incurring inefficient mass transport of CO2 . Herein, we suggest a feasible way to promote the CO2 reutilization by integrating the storage and reduction, with a new covalent organic framework (COF) series constituted by cobalt-phthalocyanine and boronic acid linkers. We find that the porous structure of the cobalt COF is competitive in the CO2 storage and can sustain a high CO2 concentration around the reduction center, whereas the mass transport of CO2 as well as the efficiency of the CO2 reduction is significantly improved. The predicted cobalt COF exhibits an overpotential of 0.27 V and a CO production rate, which is 97.7 times higher than in aqueous solution, for the CO2 reduction. Our work provides a promising candidate for the CO2 reutilization, with valuable insights and an important prototype for future practical design.

Geometric and electronic structure of multilayered graphene: synergy of the nondirective ripples and the number of layers.

According to the Mermin-Wagner theorem, ripple deformation is ubiquitous in a two-dimensional (2D) free-standing sheet, influencing the electronic properties. However, the synergistic effects of the unrestricted ripples and the number of layers have still been a topic of extensive debate. To address this issue, we employed density functional theory including many-body van der Waals (vdW) correction to investigate the effects of the nondirective ripples on the geometric and electronic structures of multilayered graphene. We found that the many-body effects of vdW forces were essential for the binding of multilayered rippled graphene. The increase of curvature affects the electronic structures of rippled graphene by modifying stacking modes, while the increase in the number of layers can reduce band gap and work function directly. The coupling of these two effects can enhance the chemical activity of rippled graphene. Our results facilitate new insights into the geometric and electronic properties of rippled graphene, which can be generalized to other layered materials.

Cobalt-porphine catalyzed CO2 electro-reduction: a novel protonation mechanism.

The urgent need for artificially fixing CO2 calls for catalysts of high efficiency. The transition metal functionalized porphyrin (TMP) is one of the most important types of organic catalysts for CO2 reduction. However, the catalytic mechanisms of TMP in CO2 reduction still remain controversial. Starting from the previously neglected catalyst self-protonation model, we uncover a new CO2 reduction mechanism on cobalt-porphine, which involves an indirect proton transfer step occurring at the beginning of the reduction cycle. Based on this protonation mechanism, we demonstrate the different correlations between producing rate and pH for the formation of CO and methane, in good agreement with available experimental observations. Our results reveal how pH and potential affect the CO2 reduction process, providing important clues and insights for further optimization of TMP catalysts.

[Research on quality standards of Aleuritopteris Herba].

This study aims to establish quality standards of Aleuritopteris Herba (AH), which could supply scientific evidence for the quality control of AH. The morphological and microscopic identification characters were reformulated. The tests of water content, total ash, acid-insoluble ash and ethanol-soluble extractives of AH were carried out according to the methods recorded in appendix of Chinese Pharmacopeia (2010 edition, volume 1). The TLC method was established by using aleuritopesis A [2,19-diol（2ß,4α）-16-enekaureniod] and reference herb as references. With preparation of aleuritopesis A[2,19-diol（2ß,4α）-16-enekaureniod] reference substance, the content of aleuritopesis A in AH was determined by HPLC. As a result, the macroscopic identification, microscopic features and TLC methods were specific and simple. The water content, total ash, acid-insoluble ash and ethanol-soluble extractive and the content of aleuritopesis A of all samples varied in the ranges of 8.8%-10.9%, 7.6%-11.4%, 2.5%-4.2%, 9.3%-10.2% and 0.56%-0.71%, respectively. The improved quality standard can be used to evaluate and guarantee the quality of AH comprehensively.

[Temporal and Spatial Variation in Odor Pollution and Membrane Barrier Effect in Municipal Solid Waste Landfill].

In order to explore the source characteristics as well as the temporal and spatial variations in odor pollution in municipal waste landfills, gas samples were collected from a landfill in an eastern coastal area of China throughout winter and summer. The total concentration of malodorous substances reached 60000 µg·m-3. There were more types of odor pollutants detected in summer than in winter, the average concentration was 30-300 times higher than that in winter, and the concentration of sulfur compounds increased by 4.7-136.7 times in summer. Oxygenated compounds had the highest concentration, and the total concentration of sulfur compounds accounted for less than 10% of malodorous substances. However, sulfur compounds contributed more than 90% to the theoretical odor concentration. Sulfur compounds such as methyl mercaptan and propane mercaptan were the key odorants in the landfill. After the landfill unit was covered, the concentration of odorous substances and the theoretical odor concentration on the surface of the landfill showed an increasing trend with time, indicating that the covering had a certain odor barrier effect; however, the landfill unit still had a large odor release potential. The similarity analysis showed that the odorous gas accumulated in the unit with temporary cover and without an exhaust system could be released to the environment through the overlapping gap of the membrane and the location of membrane rupture, resulting in more serious odor pollution around the landfill at night than that during the day.

Nonlocal Electronic Correlations in the Cohesive Properties of High-Pressure Hydrogen Solids.

High-pressure hydrogen exhibits remarkable phenomena including the insulator-to-metal (IM) transition; however, a complete resolution of its phase diagram is still an elusive goal despite many efforts and much controversy. Theoretical modeling is typically based on density functional theory (DFT) with a mean-field description of electronic correlations, which is known to be rather limited in describing IM transitions. Herein, we show that nonlocal electron correlations play a central role in the relative stability of solid hydrogen phases, and that DFT-correcting for these correlations by the many-body dispersion (MBD) model reaches the accuracy of quantum Monte Carlo (QMC) simulations and predicts the same C2/c-24 → Cmca-12 → Cs(IV) IM transition. In contrast with the conventional assumption that many-body electronic correlations become localized in metallic systems because of exponential screening with interelectronic distance, we find that the anisotropy of the electronic response of hydrogen solids under pressure leads to longer-ranged many-body effects in metallic phases relative to insulating ones. This refines our understanding of phase diagram of hydrogen solids as well as anisotropic many-body correlations.

[Chemical constituents from herb of Pholidota cantonensis].

OBJECTIVE: To study the chemical constituents of Pholidota cantonensis. METHOD: The compounds were isolated and purified on silica gel, Sephadex LH-20, Chromatorex ODS column chromatography and the structures were determined based on the spectral and chemical evidences. RESULT: Four compounds were obtained and characterized as pholidonone (1), ephemeranthoquinone (2), orchinol (3), batatasin III (4). CONCLUSION: They have been isolated from this plant for the first time and pholidonone (1) was a new compound.

Long-Term Stability of Perovskite Solar Cells under Different Growth Conditions: A Defect-Controlled Water Diffusion Mechanism.

Understanding the water-infiltration process is crucial for improving the long-term stability of perovskite solar cells (PSCs). Although many attempts have been made in this regard, the role of growth condition in PSC synthesis, which has been observed experimentally to be essential for the stability of PSCs, remains elusive. Using first-principles tools, we demonstrate that the growth condition strongly controls the water-infiltration process of PSCs by dictating the formation of point defects on PSC surfaces. The resulting point defects are found to alter both the rate and the pathways of the water-infiltration process substantially. Our work builds a new scenario for understanding the relation between the PSC decomposition mechanism and its preparation methods; it not only sheds new insights for decrypting experimental phenomenon, but also provides important guidance for future preparation of PSCs with improved water resistance.

Antagonistic effects of methanolic extract of Polygala telephioides on morphine responses in mice.

The present study was undertaken to investigate the antagonistic effects of the methanolic extract of Polygala telephioides (PT) on morphine responses in mice. Single administration of PT tended to antagonize the morphine-induced analgesia in a hot-plate test. Moreover, PT (300 mg/kg, p.o.) improved the morphine-induced memory impairment in an elevated plus maze test. However, PT alone had no effect on behaviors in the open-field, hot-plate and elevated plus maze tests. We investigated the effects of PT on naloxone-induced jumping (as withdrawal sign) in morphine-dependent mice. To induce dependence, mice were twice daily treated with morphine (10-45 mg/kg, s.c.) for 5 days. Co-administrations of PT (10, 100 and 300 mg/kg, p.o.) during repeated morphine treatments significantly suppressed the naloxone (10 mg/kg, i.p.)-induced jumping. However, the naloxone-induced jumping was not affected by a single large administration of PT on the 5th day. The inhibitory effect of PT on the naloxone-induced jumping was due to the development of dependence rather than expression of withdrawal sign. Moreover, single administration of PT (30 mg/kg, p.o.) decreased the morphine levels in plasma. These results indicate that PT may be useful in facilitating narcotic detoxification.

Determination of six polyether antibiotic residues in foods of animal origin by solid phase extraction combined with liquid chromatography-tandem mass spectrometry.

A new method using solid phase extraction (SPE) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed for the determination of six polyether antibiotics, including lasalocid, salinomycin, monensin, narasin, madubamycin and nigericin residues, in foods of animal origin. The samples were extracted with acetonitrile and purified by ENVI-Carb SPE columns after comparing the impurity effect and maneuverability of several SPE cartridges. Subsequently, the analytes were separated on a Hypersil Gold column (2.1×150mm, 5µm) and analyzed by MS/MS detection. The limit of quantization (LOQ) for milk and chicken was 0.4µg/kg, and for chicken livers and eggs, it was 1µg/kg. The linearity was satisfactory with a correlation coefficient of >0.9995 at concentrations ranging from 2 to 100µg/L. The average recoveries of the analytes fortified at three levels ranged from 68.2 to 114.3%, and the relative standard deviations ranged from 4.5 to 12.1%. The method was suitable for quantitative analysis and confirmation of polyether antibiotic residues in foods of animal origin.

Facile Synthesis of Non-Graphitizable Polypyrrole-Derived Carbon/Carbon Nanotubes for Lithium-ion Batteries.

Graphite is usually used as an anode material in the commercial lithium ion batteries (LIBs). The relatively low lithium storage capacity of 372 mAh g(-1) and the confined rate capability however limit its large-scale applications in electrical vehicles and hybrid electrical vehicles. As results, exploring novel carbon-based anode materials with improved reversible capacity for high-energy-density LIBs is urgent task. Herein we present TNGC/MWCNTs by synthesizing tubular polypyrrole (T-PPy) via a self-assembly process, then carbonizing T-PPy at 900 °C under an argon atmosphere (TNGC for short) and finally mixing TNGC with multi-walled carbon nanotubes (MWCNTs). As for TNGC/MWCNTs, the discharge capacity of 561 mAh g(-1) is maintained after 100 cycles at a current density of 100 mA g(-1). Electrochemical results demonstrate that TNGC/MWCNTs can be considered as promising anode materials for high-energy-density LIBs.

Self-grown Ni(OH)(2) layer on bimodal nanoporous AuNi alloys for enhanced electrocatalytic activity and stability.

Au nanostructures as catalysts toward electrooxidation of small molecules generally suffer from ultralow surface adsorption capability and stability. Here, we report Ni(OH)2 layer decorated nanoporous (NP) AuNi alloys with a three-dimensional and bimodal porous architecture, which are facilely fabricated by a combination of chemical dealloying and in situ surface segregation, for the enhanced electrocatalytic performance in biosensors. As a result of the self-grown Ni(OH)2 on the AuNi alloys with a coherent interface, which not only enhances adsorption energy of Au and electron transfer of AuNi/Ni(OH)2 but also prohibits the surface diffusion of Au atoms, the NP composites are enlisted to exhibit significant enhancement in both electrocatalytic activity and stability toward glucose electrooxidation. The highly reliable glucose biosensing with exceptional reproducibility and selectivity as well as quick response makes it a promising candidate as electrode materials for the application in nonenzymatic glucose biosensors.

Integrated solid/nanoporous copper/oxide hybrid bulk electrodes for high-performance lithium-ion batteries.

Nanoarchitectured electroactive materials can boost rates of Li insertion/extraction, showing genuine potential to increase power output of Li-ion batteries. However, electrodes assembled with low-dimensional nanostructured transition metal oxides by conventional approach suffer from dramatic reductions in energy capacities owing to sluggish ion and electron transport kinetics. Here we report that flexible bulk electrodes, made of three-dimensional bicontinuous nanoporous Cu/MnO2 hybrid and seamlessly integrated with Cu solid current collector, substantially optimizes Li storage behavior of the constituent MnO2. As a result of the unique integration of solid/nanoporous hybrid architecture that simultaneously enhances the electron transport of MnO2, facilitates fast ion diffusion and accommodates large volume changes on Li insertion/extraction of MnO2, the supported MnO2 exhibits a stable capacity of as high as ~1100 mA h g(-1) for 1000 cycles, and ultrahigh charge/discharge rates. It makes the environmentally friendly and low-cost electrode as a promising anode for high-performance Li-ion battery applications.

First principles study of periodic size dependent band gap variation of Cu doped ZnO single-wall nanotube.

In this contribution, the size dependent band gap variation of (Zn(4/6)Cu(2/6)O)(L)/(Zn(5/6)Cu(1/6)O)(L) (L is the periodic size) superlattices are investigated with the change of L. The results show that the variation tendency of band gap appears a minimum in S(4) (L = 4) which is nearly a conductor. The band gap of S(3) (L = 3) and S(5) (L = 5) also decrease obviously compared to the other three configurations. Especially, the band gap of S(3) has decreased to 2.16 eV which is in the region of narrow bandgap semiconductor. Thus, the band gap can be modulated by alloying through constructing an appropriate variation period. Our ZnCuO superlattices can absorb light in both visible and UV region. These properties make the superlattices a potential application in photocatalysis and the visible light emitter.

Hepatoprotective activity of the constituents in Swertia pseudochinensis.

A new xanthone derivative was isolated together with other 13 known constituents from a Chinese natural medicine, Swertia pseudochinensis HARA. Their structures were determined based on the spectral and chemical evidences. Furthermore, respective hexane, ethyl acetate, 1-BuOH, MeOH and water extracts of S. pseudochinensis, and purified compounds were respectively evaluated for their hepatoprotective activities against hepatocyte injury induced by CCl4. All the extracts and isolated compounds exhibited significant hepatoprotective activities at a dose showing no hepatoxicity.

Lignan derivatives and a norditerpene from the seeds of Vitex negundo.

A new phenyldihydronaphthalene-type lignan, vitedoin A (1), a new phenylnaphthalene-type lignan alkaloid, vitedoamine A (2), and a new trinorlabdane-type diterpene, vitedoin B (3), were isolated from the seeds of Vitex negundo along with five known lignan derivatives (4-8). Their chemical structures were determined mainly on the basis of NMR and MS data. Compounds 1, 2, and 4-7 showed stronger antioxidative activity than alpha-tocopherol using the ferric thiocyanate method. Compounds 1, 2, and 4-7 showed higher radical-scavenging effect on the stable free radical, 1,1-diphenyl-2-picrylhydrazyl, than L-cysteine.