Flame retardancy and smoke suppression of molybdenum trioxide doped magnesium hydrate in flexible polyvinyl chloride

In this paper, an effective flame retardant consisting of hierarchical magnesium hydrate (MH) nanosheets doped with molybdenum trioxide nanoparticles (MO@MH) was successfully synthesized via a hydrothermal process. Then, MO@MH, MH, and MH/MO were respectively incorporated into flexible polyvinyl chloride (fPVC) to prepare a series of composites via melt blending. The results of limiting oxygen index (LOI), UL‐94, and cone calorimetry test showed that MO@MH exhibited better flame retardancy and smoke suppression than MH and MH/MO due to the synergistic effect of MO and MH, and the hierarchical structure of MO@MH. With the addition of 20 phr MO@MH, LOI value of fPVC was increased from 23.9% to 33.8% , and UL‐94 reached V0 rating. The peak heat release rate, total heat release, peak smoke production rate, and total smoke production were decreased to 143.0 kW/m², 44.9 MJ/m², 0.0093 m²/s and 29.4 m², respectively. The thermogravimetric analysis results suggested that MO@MH greatly promoted the dehydrochlorination of fPVC at lower temperature, so that more compact and continuous char residues were formed. The Fourier transform infrared spectroscopy results indicated that MO@MH can prevent chain scission and oxidation of fPVC carbonaceous backbone, and as a result less smoke was released.     

Experimental investigation on the heat transfer characteristics of novel rectangle radial microchannel heat exchangers in two-phase flow cooling system for data centers

Journal of Thermal Analysis and Calorimetry - Biobased odd–odd poly(propylene dicarboxylate)s, based on 1,3-propanediol and three odd diacids [i.e., glutaric acid (C5), pimelic acid (C7) or...     

Functionalization of Zirconium‐Based Metal–Organic Layers with Tailored Pore Environments for Heterogeneous Catalysis

Intriguing properties and functions are expected to implant into metal–organic layers (MOLs) to achieve tailored pore environments and multiple functionalities owing to the synergies among multiple components. Herein, we demonstrate a facile one‐pot synthetic strategy to incorporate multiple functionalities into stable zirconium MOLs via secondary ligand pillaring. Through the combination of Zr₆‐BTB (BTB=benzene‐1,3,5‐tribenzoate) layers and diverse secondary ligands (including ditopic and tetratopic linkers), 31 MOFs with multi‐functionalities were systematically prepared. Notably, a metal–phthalocyanine fragment was successfully incorporated into this Zr‐MOL system, giving rise to an ideal platform for the selective oxidation of anthracene. The organic functionalization of two‐dimensional MOLs can generate tunable porous structures and environments, which may facilitate the excellent catalytic performance of as‐synthesized materials.     

Dimetallic sulfide endohedral metallofullerene Sc2S@C76: Density functional theory characterization

In terms of density functional theory combined with statistic mechanics computations, we investigated a dimetallic sulfide endohedral fullerene Sc₂S@C₇₆ which has been synthesized without any characterization in experiments. Our theoretical study reveals that Sc₂S@T_d(19151)‐C₇₆ which satisfies the isolated‐pentagon rule (IPR) possesses the lowest energy, followed by three non‐IPR structures (Sc₂S@C_2v(19138)‐C₇₆, Sc₂S@C_s (17490)‐C₇₆, and Sc₂S@C₁(17459)‐C₇₆). To clarify the relative stabilities of those isomers at high temperatures, enthalpy–entropy interplay has been taken into consideration. Calculation results indicate that three species Sc₂S@T_d(19151)‐C₇₆, Sc₂S@C_2v(19138)‐C₇₆, and Sc₂S@C₁(17459)‐C₇₆ have noticeable molar fractions at the fullerene‐formation temperature region (500–3000K), and the Sc₂S@C₁(17459)‐C₇₆ with one pentagon pair becomes the most predominant isomer above 1800 K, suggesting that the unexpected non‐IPR structure is thermodynamically favorable at elevated temperatures. In addition, the structural characteristics, electron features, UV‐vis‐NIR adsorptions, and ¹³C NMR spectra of those three stable structures are introduced to assist experimental identification and characterization in future. © 2014 Wiley Periodicals, Inc.     

Population genetics and forensic efficiency of twenty‐one novel microsatellite loci of Chinese Yi ethnic group

In this study, we investigated polymorphic distributions of allelic frequencies and forensic genetic parameters of 21 novel autosomal microsatellite loci from 110 unrelated healthy individuals of Chinese Yi ethnic group. Expected heterozygosity, power of discrimination, and polymorphic information content ranged from 0.617 to 0.812, 0.777 to 0.936 and 0.560 to 0.790. The microsatellite loci showed high forensic efficiency. The total discrimination power and cumulate probability of exclusion were 0.99999999999999999986902 and 0.999998818, respectively. Locus‐by‐locus allelic frequencies were compared using analysis of molecular variance (AMOVA) method, and the statistically significant differences were observed between Yi group and Russian, Tujia, Kazak, Bai, Ningxia Han, Salar, Tibetan, and Uigur groups at 5, 6, 7, 7, 7, 8, 12, and 13 loci, respectively. The results of genetic distance comparisons, genetic structure analyses, and principal component analysis all indicated that the Yi group showed relatively short genetic relationships with Russian, Salar, and Bai group. The experimental results showed that the 21 loci in the multiplex system provided highly polymorphic information and forensic efficiency for forensic individual identification and paternity testing, also basic population data for population genetics and anthropological research.     

Mild Copper‐Catalyzed Fluorination of Alkyl Triflates with Potassium Fluoride

A chemoselective catalytic fluorination of alkyl triflates is described using potassium fluoride as a fluoride source. Excellent yields of the desired alkyl fluorides are obtained after one hour at 45 °C using 2 mol % of the copper catalyst. With 10 mol % of the catalyst, full conversion can be achieved in less than 10 minutes at 45 °C, and thus makes this procedure potentially suited for the preparation of ¹⁸F‐labeled PET probes. As a result of the mild reaction conditions, only the substitution products are observed with no evidence of common side reactions, such as elimination. Reported is a preliminary study of the reaction scope, which demonstrates that the fluorination can be performed in the presence of a wide range of functional groups. Evidence suggests an unusual role of the [IPrCuOTf] catalyst as a phase‐transfer catalyst and points to [IPrCuF] as the active fluorinating reagent (IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene).     

Synthesis and dielectric properties of novel liquid crystalline triblock copolymers with cyanobiphenyl moieties and poly(n‐butyl acrylate) segments

In this work, self‐assembly method was used to improve the dielectric constant of triblock copolymers. A series of ABA triblock copolymers with a defined length of poly(n‐butyl acrylate) (PBA, B block) segment and different lengths of liquid crystalline (LC) poly[11‐(4‐cyano‐4′‐biphenoxy)undecyl methacrylate] (P11CBMA, A block) segments were synthesized by using the atom transfer radical polymerization method. The well‐defined triblock copolymers P11CBMA_m‐b‐PBA_n‐b‐P11CBMA_m possess three different B/A ratios (n = 50, m = 17, 43, 53). Due to the supramolecular cooperative motion effect, the copolymers can form worm‐like microstructure (W_LC = 52.8%), cylinder‐like nanostructure with P11CBMA phase embedded in PBA matrix (W_LC = 73.9%), and wide stripe structure with LC domains distributed unevenly in a continuous PBA matrix (W_LC = 77.7%) after annealed at 160°C (above T_i) under N₂ for 24 h, respectively. In order to study the influence of microphase separated morphology of triblock copolymer on the dielectric properties, solvent annealing was also used to develop various nanostructures. After thermal or solvent annealing, the dielectric constants of block copolymers increased dramatically while their loss factors remained the same. For different block copolymers, the dielectric constants increased with the increase of the LC block length. For diverse treatments, dielectric permittivities of samples varied widely with different nanostructures. The results show that the dielectric constants of block copolymers could be tuned by the block ratios and the self‐assembled microstructures. These findings will inspire researchers using self‐assembly method to design and develop novel flexible materials with high dielectric permittivity. Copyright © 2014 John Wiley & Sons, Ltd.     

Negative charge induced dissociation: fragmentation of deprotonated N‐benzylidene‐2‐hydroxylanilines in electrospray ionization mass spectrometry

Unimolecular reactivities of different N‐benzylidene‐2‐hydroxylaniline anions were investigated in gas phase by electrospray ionization tandem mass spectrometry. All the collision‐induced dissociation spectra of N‐benzylidene‐2‐hydroxylaniline anions show similar ions at phenyl anions, neutral loss of benzonitrile and benzoxazole anions, respectively. The possible fragmentation pathway was probed through deuterium labeling and various group substituents experiments. Computational results were applied to shed light on the mechanism of fragmentation patterns. The proton in the CH=N is reactive in the formation of the concerned ions. Its direct transfer to the oxygen results in 2‐hydroxyphenyl anion. Proton abstraction between benzoxazole and phenyl anion leads to the formation of benzene and benzoxazole anion. Copyright © 2014 John Wiley & Sons, Ltd.     

用核磁共振技术研究氢键的键合方式

为了了解怎样利用核磁共振技术研究氢键的键合方式,本文以联酰胺衍生物为例,分别运用变温核磁共振氢谱和变浓度核磁共振氢谱分析了羰基(CO)与氨基(H—N)之间形成氢键的形式。结果表明,本文举例中联酰胺基团中的CO与H—N以分子间氢键形式存在。     

Nano Mapper: an Internet knowledge mapping system for nanotechnology development

Nanotechnology research has experienced rapid growth in recent years. Advances in information technology enable efficient investigation of publications, their contents, and relationships for large sets of nanotechnology-related documents in order to assess the status of the field. This paper presents the development of a new knowledge mapping system, called Nano Mapper (), which integrates the analysis of nanotechnology patents and research grants into a Web-based platform. The Nano Mapper system currently contains nanotechnology-related patents for 1976–2006 from the United States Patent and Trademark Office (USPTO), European Patent Office (EPO), and Japan Patent Office (JPO), as well as grant documents from the U.S. National Science Foundation (NSF) for the same time period. The system provides complex search functionalities, and makes available a set of analysis and visualization tools (statistics, trend graphs, citation networks, and content maps) that can be applied to different levels of analytical units (countries, institutions, technical fields) and for different time intervals. The paper shows important nanotechnology patenting activities at USPTO for 2005–2006 identified through the Nano Mapper system.