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The mainstream of pyrolyzed transitional metal-nitrogen-carbon (M-N-C) catalysts for ORR still confront difficulty in PEMFC application. To pursue M-N-C structure from wet chemistry at ambient temperature, this paper prepares Fe x Co y -PANI/CNT porous structures composed of amorphous Fe and Co NPs into PANI layer on CNT surface, supported by the controlled molecular self-assembly mechanism (MS). For their ORR behaviors in acid medium, all Fe x Co y -PANI/CNT catalysts demonstrate similar features as Pt-based catalyst in low current density region, and 4e pathway and active sites in pore utilization in high current density region. Specifically, we disclosed nitrogen in PANI matrix dominates specific activity for ORR, and a little transitional metal attain mass activity at maximum. The active sites mounted into PANI matrix and 4e pathway help catalysts to achieve high durability. Thus, we extend a new type of platinum-free catalyst and develop a bottom-up approach for preparation-structure-activity, expecting to drive PEMFC remarkably. • To prepare bimetallic structure with controlled molecular self-assembly method. • To corroborate active site of M-N-C for ORR in acid medium. • The active sites mounted into PANI matrix help increase ORR durability. • Developing a bottom-up approach for preparation-structure-activity. [ABSTRACT FROM AUTHOR]

Young's modulus, failure strength, and failure strain of precracked graphene are investigated via finite element method based on molecular structure mechanics in this research. The influence of distribution, length, and orientation of precrack and graphene sizes on these mechanical properties is analyzed. The ratio of precrack length and graphene width is defined as P value, and its particular value Pc can be found, at which the variation trends of Young's modulus, failure strength, and strain have changes with increasing P value. In addition, the fracture toughness of precracked graphene is investigated, and the stress intensity factor (SIF) is calculated according to the Griffith criterion in classical fracture mechanics. The numerical values of the SIF are about 3.20-3.37 MPa√m, which are compared with the experimental results, and the simulations verify the applicability of the classical fracture mechanics to graphene. [ABSTRACT FROM AUTHOR]

The mechanical properties of bicrystalline graphene nanoribbons with various tilt grain boundaries (GBs) which typically consist of repeating pentagon–heptagon ring defects are investigated based on the method of molecular structural mechanics. The GB models are constructed via the theory of disclinations in crystals, and the elastic properties and ultimate strength of bicrystalline graphene nanoribbons are calculated under uniaxial tensile loads in perpendicular and parallel directions to grain boundaries. The dependence of mechanical properties is analyzed on the chirality and misorientation angles of graphene nanoribbons, and the experimental phenomena that Young's modulus and ultimate strength of bicrystalline graphene nanoribbons can either increase or decrease with the grain boundary angles are further verified and discussed. In addition, the influence of GB on the size effects of graphene Young's modulus is also analyzed. [ABSTRACT FROM AUTHOR]

Abstract: Molecular structural mechanics based finite element method is applied to study the influence of the two types of Stone–Wales defects on the elastic properties of monolayer and multilayer graphene nanofilms. Models with spatial frame structures are developed to simulate the graphene crystal with Stone–Wales defects based on the linkage between the inter-atomic potential energy in molecular mechanics and the strain energy in classical structural mechanics. Several possible influencing factors, including the number and types of Stone–Wales defects, the distance between two defects and the position of defects in the graphene, are taken into account to evaluate Young''s moduli and Poisson''s ratios of armchair and zigzag monolayer graphene nanofilms. It is shown that the Stone–Wales defects have remarkable influence on the elastic properties of monolayer graphene. In addition, the size-dependent Young''s moduli and Poisson''s ratios of multilayer graphene nanofilms are also investigated when the Stone–Wales defects in surface layers are taken into consideration. [Copyright &y& Elsevier]

Abstract: This work presents six CuII, CoII, and NiII supramolecular complexes assembled from a bent dipyridyl ligand 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (3-bpo) and R-isophthalic acids (R =–CH3 for 5-methylisophthalic acid or R =–OCH3 for 5-methoxyisophthalic acid), which have been prepared using the layer-separation diffusion method and fully characterized by IR, elemental analysis, and powder X-ray diffraction (PXRD) techniques. Single-crystal X-ray diffraction indicates that these complexes show 1-D tube-like (for CuII complexes 1 and 2) or discrete cage-like dinuclear (for CoII and NiII complexes 3–6) coordination patterns. Furthermore, extended 3-D supramolecular architectures are constructed via secondary interactions between the coordination arrays, and three types of packing fashions are observed for the dinuclear species 3–6. Structural diversification for these complexes can be properly attributed to the inherent discrepancy of metal ions and the substituent effect of R-isophthalate tectons. [Copyright &y& Elsevier]

Abstract: Reactions of 1,4-naphthalenedicarboxylic acid (1,4-H2nda) and a bent dipyridyl co-ligand 4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole (4bpt) with CoII, ZnII, or CdII acetate afford four coordination polymers, [Co(1,4-nda)(4bpt)(H2O)] n (1), {[Co(1,4-nda)2(4bpt)(H2O)2][Co(4bpt)(H2O)4](H2O)1.5} n (2), {[Zn(1,4-nda)2(4bpt)(H2O)2][Zn(4bpt)(H2O)4](H2O)1.5} n (3), and {[Cd2(1,4-nda)2(4bpt)2(H2O)2](DMF)1.5(H2O)3} n (4). In the structure of the CoII complex 1, the polycatenation of inclined 2-D (4,4) coordination layers leads to the formation of a 3-D supramolecular framework, whereas two types of 1-D polymeric chains are observed in another CoII coordination species 2, which are interconnected via H-bonding to result in an unusual 3-D host–guest lattice. Notably, complexes 1 and 2 have been prepared under similar hydrothermal conditions and their structural discrepancy can only be ascribed to a subtle change of basicity for the reaction solution. The ZnII complex 3 is isostructural to 2, and the CdII complex 4 displays a 2-fold parallel interpenetrating array of undulating (4,4) coordination layers. By using the conventional solvent evaporation method, two PbII naphthalenedicarboxylates [Pb(1,4-nda)(DMF)] n (5) and {[Pb2(2,6-nda)2(DMF)2](DMF)} n (6) have also been prepared (2,6-nda=2,6-naphthalenedicarboxylate). Complex 5 has a unique 5-connected 3-D coordination architecture, whereas 6 represents a 3-fold interpenetrating framework of 4-connected diamond topology. Their structural difference suggests the significant isomeric effect of the naphthalenedicarboxylate tectons on structural assemblies. Thermal stability of these crystalline materials has been investigated by thermogravimetric and differential thermal analysis (TG–DTA) technique and solid-state luminescent properties of the ZnII, CdII, and PbII complexes have also been explored. [Copyright &y& Elsevier]

Autosomal recessive hearing impairment with postlingual onset is rare. Exceptions are caused by mutations in the TMPRSS3 gene, which can lead to prelingual (DFNB10) as well as postlingual deafness (DFNB8). TMPRSS3 mutations can be classified as mild or severe, and the phenotype is dependent on the combination of TMPRSS3 mutations. The combination of two severe mutations leads to profound hearing impairment with a prelingual onset, whereas severe mutations in combination with milder TMPRSS3 mutations lead to a milder phenotype with postlingual onset. We characterized a Chinese family (number FH1523) with not only prelingual but also postlingual hearing impairment. Three mutations in TMPRSS3, one novel mutation c.36delC [p.(Phe13Serfs⁎12)], and two previously reported pathogenic mutations, c.916G>A (p.Ala306Thr) and c.316C>T (p.Arg106Cys), were identified. Compound heterozygous mutations of p.(Phe13Serfs⁎12) and p.Ala306Thr manifest as prelingual, profound hearing impairment in the patient (IV: 1), whereas the combination of p.Arg106Cys and p.Ala306Thr manifests as postlingual, milder hearing impairment in the patient (II: 2, II: 3, II: 5), suggesting that p.Arg106Cys mutation has a milder effect than p.(Phe13Serfs⁎12). We concluded that different combinations of TMPRSS3 mutations led to different hearing impairment phenotypes (DFNB8/DFNB10) in this family. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis and characterization of a class of group 4 metal derivatives based on the silyl-linked bis(amidinate) ligands [SiMe2{NC(Ph)N(2,6-R2Ph)Li}2] [L1 (R=H) and L2 (R=Me)] are described. The metal salts coordinated with cyclopentadienyl were used in order to increase the steric hindrance and lower the Lewis acidity of metal centers, which could prevent the N-ligands from rearranging. The tetradentate ligands L1 and L2 reacted with TiCl2(C5H5)2 to give compounds 1 and 2 in tridentate and bidentate bonding modes, respectively. Treatment of the ligand L1 with ZrCl3(C5H5) produced the half-sandwich zirconium complex 3. Reactions of the ligands with ZrCl2(C5H5)2 afforded zirconium compounds 4 and 5, demonstrating the same geometry as 1. Comparing these analogous molecular structures, it suggests that the coordination modes of the N-ligands are variable according to the properties of the metal centers as well as the bulky hindrance of the terminal groups on the seven-membered N–C–N–Si–N–C–N backbone. [Copyright &y& Elsevier]

Male infertility induced by heat stress has been attracting more and more attention. Heat stress not only causes apoptosis of spermatocytes but also has adverse effects on Sertoli cells, further damaging spermatogenesis. Lycium barbarum polysaccharide (LBP) is the main bioactive component of Lycium barbarum, which has a protective effect on male reproduction, but its mechanism is still unclear. In this study, our results proved that LBP blocked the inhibitory effect on the proliferation activity of Sertoli cells after heat stress, reversed the dedifferentiation of Sertoli cells induced by heat stress, and ameliorated the structural integrity of the blood-testis barrier. In addition, it increased the expression of the androgen receptor and activated Akt signaling pathway to resist heat-stress-induced injury of Sertoli cells. [ABSTRACT FROM AUTHOR]

One new β,γ-butenoate derivative phenylbutenote (1), and one new α-pyrone nocapyrone T (2) were isolated from the deep-sea derived actinomycete Nocardiopsis sp. HDN 17-237. Their structures were elucidated by extensive HRMS, IR and NMR analyses. Among them, compound 1 is the first microbial natural products bearing a rare β,γ-butenoate moiety, and compound 2 is the first α-pyrone isolated from strain of Mariana Trench. Compounds 1 and 2 were tested for antioxidant and antibacterial activities, while none of them showed significant activity. [ABSTRACT FROM AUTHOR]

Members of genus Sphingopyxis are frequently found in diverse eco-environments worldwide and have been traditionally considered to play vital roles in the degradation of aromatic compounds. Over recent decades, many aromatic-degrading Sphingopyxis strains have been isolated and recorded, but little is known about their genetic nature related to aromatic compounds biodegradation. In this study, bacterial genomes of 19 Sphingopyxis strains were used for comparative analyses. Phylogeny showed an ambiguous relatedness between bacterial strains and their habitat specificity, while clustering based on Cluster of Orthologous Groups suggested the potential link of functional profile with substrate-specific traits. Pan-genome analysis revealed that 19 individuals were predicted to share 1,066 orthologous genes, indicating a high genetic homogeneity among Sphingopyxis strains. Notably, KEGG Automatic Annotation Server results suggested that most genes pertaining aromatic compounds biodegradation were predicted to be involved in benzoate, phenylalanine, and aminobenzoate metabolism. Among them, β-ketoadipate biodegradation might be the main pathway in Sphingopyxis strains. Further inspection showed that a number of mobile genetic elements varied in Sphingopyxis genomes, and plasmid-mediated gene transfer coupled with prophage- and transposon-mediated rearrangements might play prominent roles in the evolution of bacterial genomes. Collectively, our findings presented that Sphingopyxis isolates might be the promising candidates for biodegradation of aromatic compounds in pollution sites. [ABSTRACT FROM AUTHOR]

Three new lanostanoid triterpenes, 3β,7β,15β-trihydroxy-11,23-dioxo-lanost-8,16-dien-26-oic acid (1), 3β,7β,15β-trihydroxy-11,23-dioxo-lanost-8,16-dien-26-oic acid methyl ester (2), and 3β,15β-dihydroxy-7,11,23-trioxo-lanost-8,16-dien-26-oic acid methyl ester (3) were isolated from the EtOAc extract of the fruiting bodies ofGanoderma tropicum. Their structures were elucidated on the basis of 1D and 2D NMR spectroscopy as well as MS. The bioassay of inhibitory activity against acetylcholinesterase (AChE) of these isolates was evaluated and compound2exhibited definite inhibitory activity against AChE. [ABSTRACT FROM PUBLISHER]

Abstract: The alkyl chain-linked diimidazolium (or dibenzimidazolium) salts, 1,1′-diethyl-4,4′-tetramethylene-diimidazolium-diiodide (L1H2 ·I2 ) and 1,1′-diethyl-3,3′-trimethylene-dibenzimidazolium-diiodide (L2H2 ·I2 ), and their silver(I) and copper(II) coordination polymers, [L1AgI] n (1) and [L2Cu2I4] n (2), have been prepared and characterized. Complex 1 is a 1D helical polymer generated by bidentated carbene ligands (L1) and Ag(I) atoms. The 1D polymer of 2 is formed by bidentated carbene ligands (L2) and coplanar quadrilateral Cu2I2 units. 3D supramolecular frameworks in the crystal packings of 1 and 2 are formed via intermolecular weak interactions, including C–H···π contacts, π–π interactions and C–H···I hydrogen bonds. [Copyright &y& Elsevier]

Abstract: Assemblies of an angular dipyridyl ligand 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (4-bpo) with a series of metal perchlorate afford five new supramolecular complexes with the general formula of [M(4-bpo)2(H2O)4]·(4-bpo)2 ·(anion)·(solvent), in which M=MnII for 1, FeII for 2, CoII for 3, ZnII for 4, and FeIII for 5. Although similar molecular structures and compositions are found for these mononuclear complexes, they display two types of supramolecular lattices. Complexes 1, 4 and 5 similarly crystallize in space group P2/n or P2/c. The complex cations, free 4-bpo and lattice water are linked to generate 2D layered frameworks with the aid of hydrogen bonding, and the counter anions are located within and between (also methanol in 5) these 2D arrays. However, complexes 2 and 3 are isostructural in space group . Two types of alternate 2D layers consisting of complex cations and free 4-bpo components, respectively, are observed with the anions and lattice water locating between them. These motifs are interlinked by complicated hydrogen-bonding to form a 3D intercalated network. Moreover, when Co(NO3)2 is used instead of Co(ClO4)2 in the assembly of 3, a 1D polymeric chain complex {[Co(4-bpo)(H2O)2(NO3)2](H2O)3} n (6) is generated. These results indicate that the choice of metal ion and anion exerts a significant influence on governing the target complexes. A comparison of the structural features for all metal perchlorate complexes with 4-bpo is also briefly discussed. [Copyright &y& Elsevier]