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In order to improve its water resistance and compatibility with polymer matrix, ammonium polyphosphate (APP) is modified with melamine‐trimesic acid (MEL‐TA) aggregates by supramolecular self‐assembly technology. Chemical structure and morphology of APP@MEL‐TA are investigated by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM), respectively. Intumescent flame retardant system of APP@MEL‐TA and charring‐foaming agent is introduced into polypropylene (PP) matrix. The flammability and combustion behavior of PP composites are investigated by limiting oxygen index (LOI), UL‐94 vertical burning, and cone calorimetry tests. In terms of LOI values and cone combustion results, APP@MEL‐TA performs better than pristine APP. Char residue of PP composites is investigated by SEM and Raman spectra. Flame retardant mechanisms are proposed based on thermal decomposition, combustion results, and analysis on char residue. [ABSTRACT FROM AUTHOR]

Piperazine cyanurate (PCA) is designed and synthesized via hydrogen‐bonding self‐assembly reactions between piperazine and cyanuric acid. Chemical structure and morphology of PCA are investigated by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. The prepared PCA is combined with ammonium polyphosphate (APP) to prepare flame‐retardant polypropylene (PP) composites. Thermostability, flammability, and combustion characteristics of PP composites are analyzed. The maximum thermal decomposition rate of flame‐retarded PP composites has an apparent reduction compared with that of pure PP, and obvious char is left for this intumescent flame retardant (IFR) system of APP and PCA. A high limiting oxygen index value and UL‐94 V‐0 rating are achieved with addition of APP and PCA. In cone calorimetry test, heat and smoke releases of PP are significantly decreased by this IFR system. Gaseous decomposition products during the thermal decomposition of flame‐retardant composites are studied. Chemical structure and morphology of char residues are analyzed. The results illustrate that APP and PCA have a superb synergistic action in the aspect of improvement in fire safety of PP. A possible flame‐retardant mechanism is concluded to reveal the synergism between APP and PCA. [ABSTRACT FROM AUTHOR]

The identification of hydrogen in a range of lunar samples and the similarity of its abundance and isotopic composition with terrestrial values suggest that water could have been present in the Moon since its formation. To quantify the effect of water on early lunar differentiation, we present new analyses of a high‐pressure, high‐temperature experimental study designed to model the mineralogical and geochemical evolution of the solidification material equivalent to 700 km deep lunar magma oceans first reported in Lin et al. (2017a). We also performed additional experiments to better quantify water contents in the run products. Water contents in the melt phases in hydrous run products spanning a range of crystallization steps were quantified directly using a secondary ion mass spectrometry (SIMS). Results suggest that a significant but constant proportion (68 ± 5%) of the hydrogen originally added to the experiments was lost from the starting material independent of run conditions and run duration. The volume of plagioclase formed during our crystallization experiments can be combined with the measured water contents and the observed crustal thickness on the Moon to provide an updated lunar interior hygrometer. Our data suggest that at least 45–354 ppm H2O equivalent was present in the Moon at the time of crust formation. These estimates confirm the inference of Lin et al. (2017a) that the Moon was wet during its magma ocean stage, with corrected absolute water contents now comparable to estimates derived from the water content in a range of lunar samples. [ABSTRACT FROM AUTHOR]

γ‐Al2O3 nanoflakes are decorated on the surface of graphene nanosheets by hydrothermal method. The chemical structures, composition, and morphology of the graphene nanohybrid are characterized. Alumina nanoflake‐coated graphene nanohybrid is incorporated into polypropylene (PP) matrix by master batch‐based melt mixing method. The effects of alumina‐graphene nanohybrid on the thermal stability and combustion behavior of PP are investigated. More char residue is left for PP composite containing alumina‐graphene nanohybrid. Peak heat release rate of pure PP is greatly decreased by this nanohybrid, corresponding to 30.6% reduction. Fire safety of PP is considerably enhanced. Flame retardant mechanisms are concluded based on the combustion results and char analysis. The barrier effect of graphene and catalytic charring actions of γ‐Al2O3 nanoflakes make the contribution to the enhanced flame retardant properties. [ABSTRACT FROM AUTHOR]

Zirconium phenylphosphonate (ZrPP) nanoplatelets are decorated on the surface of reduced graphene oxide (RGO) based on π–π assembly interactions. The structure, composition, and morphology of ZrPP‐RGO assembly nanohybrid are well characterized. The dispersion of graphene in the nonpolar polypropylene (PP) matrix is improved by this modification. The enhancement mechanisms of dispersion in polymer matrix are clearly demonstrated. Significant improvements in flame retardancy and fire safety of PP are obtained by the incorporation of this assembly nanohybrid. Peak heat release rate and total heat release of PP composite containing 2 wt% ZrPP‐RGO assembly nanohybrid decrease by 35.8% and 23.6%, respectively, compared to those of neat PP. The assembly nanohybrid exhibits higher flame‐retardant effect than the counterparts of RGO and ZrPP. Furthermore, storage modulus of PP is greatly improved by this nanohybrid. This work proposes a novel method to prepare graphene‐based organic–inorganic nanohybrid and will expand the application of graphene. POLYM. COMPOS., 40:E1757–E1765, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The effect of sodium chloride (NaCl) on cadmium (Cd) uptake, translocation, and oxidative stress was investigated using 2 tobacco cultivars differing in Cd tolerance. The growth inhibition of the tobacco plants exposed to Cd toxicity was in part alleviated by moderate addition of NaCl in the culture solution. Cadmium concentration of shoots and roots in the 2 cultivars increased with increasing Cd levels in the solution and decreased with the addition of NaCl. The addition of NaCl could alleviate the oxidative stress caused by Cd toxicity, as reflected by reduced production of malondialdehyde and recovered or enhanced activities of antioxidative enzymes catalase and glutathione peroxidase. The results also showed that the enhancement of antioxidative enzyme activity by NaCl for the tobacco plants exposed to Cd stress is related to induced Ca signaling. Environ Toxicol Chem 2013;32:1420-1425. © 2013 SETAC [ABSTRACT FROM AUTHOR]

In the title compound, C(14)H(11)BrN(2)O(2), the mean planes of the two benzene rings are almost parallel to each other, making a dihedral angle of 4.09 (1)°. An intra-molecular O-H⋯N hydrogen bond occurs. In the crystal, inter-molecular O-H⋯N and C-H⋯O hydrogen bonds link the mol-ecules into a chain-like supra-molecular structure.

The complete mol-ecule of the title compound, C(22)H(28)N(2)O(4), is generated by a crystallographic inversion centre at the mid-point of the central C-C bond. The two benzene rings are parallel to each other with a perpendicular inter-planar spacing of 1.488 (2) Å. Intra-molecular O-H⋯N hydrogen bonds generate two six-membered rings with S(6) motifs. In the crystal, weak inter-molecular C-H⋯O hydrogen bonds link neighbouring mol-ecules into an infinite three-dimensional network, which is further stabilized by weak C-H⋯π inter-actions.

In the title compound, C(26)H(24)N(4)O(2), the dihedral angles between the central pyrazole ring and the other three benzene rings are 40.02 (3), 77.51 (5) and 55.72 (3)°. A strong intra-molecular N-H⋯O hydrogen bond forms a six-membered ring with an S(6) motif. In the crystal structure, a weak inter-molecular C-H⋯N inter-action with graph-set motif R(2) (2)(8) and C-H⋯O hydrogen bonds link each mol-ecule to three others, forming an infinite two-dimensional supra-molecular structure.

In the title centrosymmetric mononuclear copper(II) complex, [Cu(C(8)H(7)BrNO(2))(2)], the Cu(II) atom, lying on an inversion centre, is four-coordinated in a trans-CuN(2)O(2) square-planar geometry by two phenolate O atoms and two oxime N atoms from two symmetry-related N,O-bidentate oxime-type ligands. Inter-molecular C-H⋯O hydrogen bonds link neighbouring mol-ecules into a one-dimensional supra-molecular structure with an R(2) (2)(14) ring motif. This structure is further stabilized by π-π stacking inter-actions between adjacent benzene rings [centroid-centroid distance = 3.862 (1) Å].

The title compound, [Cu(C(9)H(9)BrNO(2))(2)], is a centrosymmetric mononuclear copper(II) complex. The Cu atom is four-coordinated in a trans-CuN(2)O(2) square-planar geometry by two phenolate O and two oxime N atoms from two symmetry-related N,O-bidentate (E)-4-bromo-2-(ethoxy-imino-meth-yl)phenolate oxime-type ligands. An inter-esting feature of the crystal structure is the centrosymmetric inter-molecular Cu⋯O inter-action [3.382 (1) Å], which establishes an infinite chain structure along the b axis.

The title compound, C(24)H(32)N(2)O(4), has a crystallographic inversion centre at the mid-point of the central C-C bond. At each end of the mol-ecule, intra-molecular O-H⋯N hydrogen bonds generate six-membered S(6) ring motifs. The crystal structure is stabilized by pairs of weak inter-molecular C-H⋯O hydrogen bonds that link neighbouring mol-ecules into R(2) (2)(40) ring motifs, which in turn form infinite one-dimensional supra-molecular ribbon structures.

The salen-type bis-oxime title compound, C(26)H(36)N(2)O(4), lies about a crystallographic inversion centre. Classical intra-molecular O-H⋯N hydrogen bonds generate two S(6) ring motifs. In the crystal structure, pairs of weak inter-molecular C-H⋯O hydrogen bonds link adjacent mol-ecules into an infinite one-dimensional supra-molecular structure.

The mol-ecule of the title compound, C(31)H(34)N(2)O(4), adopts an L-shaped configuration, in which the naphthalene units are approximately perpendicular, making a dihedral angle of 87.89 (3)°. Intramolecular H-bonds are formed between the OH substituents and the N atoms at each end of the molecule. In the crystal structure, each mol-ecule links six other mol-ecules into an infinite three-dimensional network supra-molecular structure, which is built from one-dimensional zigzag chains via weak C-H⋯π stacking and inter-molecular C-H⋯O hydrogen bonds.

The title complex, [Cu(C(26)H(22)N(2)O(4))], is isostructural with its Ni analogue. All intramolecular distances and angles are very similar for the two structures, whereas the packing of the molecules, including C-H⋯O and C-H⋯π interactions, are slightly different.

The title compound, C(29)H(30)N(2)O(4), adopts a distorted Z configuration with respect to the oxime group, which is almost coplanar with the adjacent naphthalene ring [dihedral angle = 4.11 (2)°]. There is one half-mol-ecule in the asymmetric unit, with a crystallographic twofold rotation axis passing through the central C atom of the -CH=N-O-(CH)(5)-O-N=CH- bridge. Within the mol-ecule, the dihedral angle formed by the two naphthalene rings is 79.08 (3)°, and there are two intra-molecular O-H⋯N hydrogen bonds.