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Rapid and facile self-assembly coatings play a crucial role in surface functionalization of materials. In this study, a safe, fast, and environmentally friendly method is proposed to form a metal-phenolic network (MPN) through the assembly of gallic acid (GA) and iron ions ([Fe.sup.3+]), which is used for the in situ polymerization coating of l,3,5,7-tetranitro-l,3,5-7-tetrazacyclooctane (HMX). The surface of the modified HMX crystals become visibly roughened. Thermoplastic polyurethane (TPU) was coated on the surface of modified HMX by water suspension method to form HMX@MPN@TPU double-layer core-shell energetic composite material. Compared with the raw material HMX, the [beta]-[delta] phase transition temperature of the double-layer core-shell structure composite increased by 12.36[degrees]C, the impact sensitivity and friction sensitivity decreased, and the compressive strength increased by 38%, which effectively improved its mechanical properties. Highlights * It has been demonstrated that metal-phenolic networks can self-assemble on the surface of crystals. * A water suspension method was employed to prepare energetic material powder into a polymer-bonded explosive (PBX). * The modified PBX showed significant improvements in various properties, indicating that metal-phenolic networks can serve as excellent modifying materials. KEYWORDS bilayer core-shell energetic composite, HMX, in situ polymerization method, metal-phenolic network, 1 | INTRODUCTION Energetic materials have the advantages of high energy density, high combustion speed, and high explosiveness, so they have attracted wide attention in the military field. (1-3) Among [...]

C12H17N9O8, orthorhombic, Pna21 (no. 33), a = 11.376(4) Å, b = 7.966(2) Å, c = 19.076(6) Å, V = 1728.6(9) Å3, Z = 4, Rgt(F) = 0.0373, wRref(F2) = 0.0908, T = 296 K.

An effect of decision errors on the decision-directed (DD) algorithm for residual carrier frequency offset (RCFO) estimation is analyzed, and a new signal-to-noise ratio (SNR)-assisted DD algorithm is proposed to estimate the RCFO in wireless orthogonal frequency-division multiplexing (OFDM) systems. In the algorithm, the received data on the subchannels with high SNRs are employed in the cross-correlation operation between the adjacent OFDM symbols, and the data of the cross correlation on the subchannels are hard decided. With these decisions and the SNR-weighted factors on the subchannels, the new algorithm estimates the RCFO in high accuracy. The simulation results indicate that the proposed scheme achieves a much better performance than the conventional DD schemes. Index Terms--Decision-directed (DD), orthogonal frequency-division multiplexing (OFDM), residual carrier frequency offset (RCFO), synchronization.

C12H17N9O8, orthorhombic, Pna21 (no. 33), a = 11.376(4) Å, b = 7.966(2) Å, c = 19.076(6) Å, V = 1728.6(9) Å3, Z = 4, Rgt(F) = 0.0373, wRref(F2) = 0.0908, T = 296 K. [ABSTRACT FROM AUTHOR]

C12H17N9O8, orthorhombic, Pna21 (no. 33), a = 11.376(4) Å, b = 7.966(2) Å, c = 19.076(6) Å, V = 1728.6(9) Å3, Z = 4, Rgt(F) = 0.0373, wRref(F2) = 0.0908, T = 296 K. [ABSTRACT FROM AUTHOR]

Chemical hazardous substances in teethers may migrate into infant's body through oral exposure, resulting in a potential health risk. In recent years, researchers have performed a series of studies for detecting target chemicals in teethers and other toys, but the presence of unknown chemicals has not been systematically investigated yet. This paper reports the non-targeted identification of unknown chemical hazards that may have migrated from teethers to infants based on gas chromatography-Orbitrap high resolution mass spectrometry. In view of the difficulties that may be encountered in the qualitative analysis of substances, several typical cases and the corresponding reliable solutions are given from the perspective of comprehensive score and retention index, isotope-aided qualitative analysis, chemical ionization identification formula, and fragment ion detail comparison for distinguishing isomers. Finally, 28 substances are identified in 10 teether samples. Among them, phenol, N -methylaniline, 1,6-dioxacyclododecane-7,12-dione and cyclohexanone have higher detection rates. This study not only has valuable reference for the identification of unknown substances, but also has positive guiding role in monitoring potential chemical hazards in toys and promoting the safety of products. [Display omitted] • This study explored the potential unknown chemical hazards in infant teethers. • Non-targeted identification method was developed with GC-Orbitrap MS. • Typical qualitative cases and the corresponding reliable solutions were given. • 28 substances, such as phenol and N -methylaniline, were identified in teethers. • This study helps to better identify potential chemical risks and ensure products safety. [ABSTRACT FROM AUTHOR]

Objective: To establish a method of combining gas chromatography-mass spectrometry (GC-MS) with head-space solid phase micro-extraction (HS-SPME) for the detection of 2,4,6-trichloroanisole (2,4,6-TCA) in wine., Methods: 2,4,6-TCA in wine were extracted by polydimethylsiloxane (PDMS,100 microm) fiber for 15 min under 35 degrees C in a water bath. The fiber was then transferred into the injection port of the GC-MS and separated by a CP-SIL 8CB-MS capillary column (30m x 0.25mm x 0.25 microm), and detected by mass spectrometry using d5-2,4,6-TCA as an internal standard., Results: The linear range for 2,4,6-TCA was 5 (60ng/L, the detection limit was 0.06ng/L. The recovery of standard addition (5, 10, 20ng/L) was in the range of 79.8% (101.6% with relative standard deviations (RSD, n=5) < or = 7%., Conclusion: Organic solvents were avoided and the selection was sensitive for the method, which is suitable for the determination of 2,4,6-TCA in wine.