Development of core‐shell structure aided by SiC‐coated MWNT in ABS/LCP blend

Agglomeration is an issue of major concern for unmodified multi‐walled carbon nanotubes (MWNTs)‐aided polymeric composites. To overcome the above‐mentioned problem, multi‐walled carbon nanotubes (MWNTs) are modified by polycarbosilane (PCS)‐derived Silicone carbide (SiC). Acrylonitrile Butadiene Styrene (ABS)/Liquid Crystalline polymer (LCP)/MWCNT nanocomposites are prepared through melt blending in a twin screw extruder. X‐Ray Diffraction (XRD) studies authenticate the creation of ß‐SiC particles. Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) studies reveal the formation of core–shell morphology involving MWNT as the core and SiC‐coated MWNT as the shell. The degree of dispersion of MWNT is far better when it has been coated with SiC. As viewed from Thermo‐gravimetric analysis (TGA), the thermal stability is substantially increased in SiC‐aided nanocomposite in comparison to ABS/LCP/unmodified CNT blend. Glass transition temperature as well as mechanical properties are improved significantly (in the presence of SiC‐coated MWNT) as a result of homogeneous dispersion exhibited by MWNT. Copyright © 2009 John Wiley & Sons, Ltd.     

Simultaneous Voltammetric Determination of Cd2+ and Pb2+ in Gasoline Samples Employing a Chemically Modified Acrylonitrile-Butadiene-Styrene (ABS) Composite Electrode

A composite electrode based on acrylonitrile-butadiene-styrene and graphite chemically modified with a bismuth film (AGCE-BiF) was applied for the simultaneous determination of Cd²⁺ and Pb²⁺ in gasoline samples. Extraction induced by microemulsion breaking (EIMB) was used for the first time in the preparation of the samples for electroanalysis. AGCE-BiF was characterized by SEM, AFM, CV, and SWASV. The sensor showed an increase in sensitivity via in situ modification with bismuth film. The LOD was 4 μg L⁻¹ for Cd²⁺ and 2 μg L⁻¹ for Pb²⁺. The results showed satisfactory recoveries and precision, being statistically compatible to those obtained with FAAS.     

Phenolic Profile,Antioxidant Capacity and Antimicrobial Activity of Nettle Leaves Extracts Obtained by Advanced Extraction Techniques

Nettle is a widely known plant whose high biological activity and beneficial medicinal effects are attributed to various bioactive compounds, among which polyphenols play an important role. In order to isolate polyphenols and preserve their properties, advanced extraction techniques have been applied to overcome the drawbacks of conventional ones. Therefore, microwave-assisted extraction (MAE) has been optimized for the isolation of nettle leaves polyphenols and it was compared to pressurized liquid extraction (PLE) and conventional heat-reflux extraction (CE). The obtained extracts were analyzed for their individual phenolic profile by UPLC MS² and for their antioxidant capacity by ORAC assay. MAE proved to be the more specific technique for the isolation of individual phenolic compounds, while PLE produced extracts with higher amount of total phenols and higher antioxidant capacity. Both techniques were more effective compared to CE. PLE nettle extract showed antimicrobial activity against bacteria, especially against Gram-negative Pseudomonas fragi ATCC 4973 and Campylobacter jejuni NCTC 11168 strains. This suggests that PLE is suitable for obtaining a nettle extract with antioxidant and antimicrobial potential, which as such has great potential for use as a value-added ingredient in the food and pharmaceutical industry.     

“互联网+”背景下混合式教学在“先进纤维材料”课程中的应用*

“先进纤维材料”是我校高分子材料与工程专业的一门专业课程,在培养高分子材料专业技术人才方面起着重要的作用。在互联网高度发达的今天,将基于Canvas教学平台的混合式教学引入“先进纤维材料”教学过程中,把常规的面对面课堂教学与网络教学的优势充分结合,激发学生对专业知识的学习兴趣,加深对所学内容的理解和记忆。同时,为了将教学内容变得更生动形象,针对每一章节重难点录制微课并在其中插入更加直观的视频动画,上传至Canvas教学平台,供学生在课前对所学内容进行自主学习,提高学生自主学习和个性化学习能力。     

顶空气相色谱-质谱法测定ABS塑料玩具中丙烯腈和苯乙烯的残留量与迁移量

该文建立了ABS塑料玩具中丙烯腈和苯乙烯两种单体残留量与迁移量的顶空气相色谱-质谱测定方法.首先对残留量测定方法的顶空平衡时间和平衡温度进行了优化,然后以模拟汗液和模拟唾液为迁移基质,对迁移量测定方法的顶空平衡时间、平衡温度、取样体积和盐析条件进行了优化,并将其应用于市售38件ABS玩具实际样品的检测.结果显示:残留量...     

Synthesis and characteristics of a novel silicon‐containing flame retardant and its application in poly[2,2‐propane‐(bisphenol)carbonate]/acrylonitrile butadiene styrene

Novel halogen‐free compounds [9,10‐dihydro‐9‐oxa‐10‐phosphaphanthrene‐10‐oxide/vinyl methyl dimethoxysilane/N‐β‐(aminoethyl)‐γ‐aminopropyl methyl dimethoxysilane (DOPO–VMDMS–NMDMS)] that simultaneously contain phosphorus, nitrogen, and silicon have been synthesized through the reaction of 9,10‐dihydro‐9‐oxa‐10‐phosphaphanthrene‐10‐oxide (DOPO), vinyl methyl dimethoxysilane (VMDMS), and N‐β‐(aminoethyl)‐γ‐aminopropyl methyl dimethoxysilane (NMDMS). The chemical structure and properties of DOPO–VMDMS–NMDMS have been investigated with Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, phosphorous nuclear magnetic resonance, and thermogravimetric analysis (TGA). These synthesized flame retardants have been blended with a poly[2,2‐propane‐(bisphenol) carbonate]/acrylonitrile butadiene styrene (PC/ABS) alloy. The flame‐retardant properties of these mixture samples have been estimated with the limiting oxygen index (LOI), and the thermal stability has been characterized with TGA. The LOI value of PC/ABS/DOPO–VMDMS–NMDMS is enhanced up to 27.2 vol % from 21.2 vol %, and the char yield is also improved slightly (from 12 to 17%) with 2.8 wt % phosphorus, 3.0 wt % silicon, and 0.5 wt % nitrogen (at a 30 wt % loading of DOPO–VMDMS–NMDMS). The results show that there is a synergistic effect of the elements phosphorus, silicon, and nitrogen on the flame retardance. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1542–1551, 2007     

移动卫星多路复用器中的传真业务

移动卫星多路复用器采用ＡＭＢＥ 语音压缩技术对多路话音信号和传真报文进行复用，以降低昂贵的通信费用。为了实时传输话音信息，传真业务只能采用非实时方式，利用存储转发技术来实现。在实现过程中，应考虑传真接口模块与其他传真机的兼容性问题     

An Image Encryption Algorithm Based on Discrete-Time Alternating Quantum Walk and Advanced Encryption Standard

This paper proposes an image encryption scheme based on a discrete-time alternating quantum walk (AQW) and the advanced encryption standard (AES). We use quantum properties to improve the AES algorithm, which uses a keystream generator related to AQW parameters to generate a probability distribution matrix. Some singular values of the matrix are extracted as the key to the AES algorithm. The Rcon of the AES algorithm is replaced with the elements of the probability distribution matrix. Then, the ascending order of the size of the clone probability distribution matrix scrambles the mapping rules of the S-box and ShiftRow transformations in the AES algorithm. The algorithm uses a probability distribution matrix and plaintext XOR operation to complete the preprocessing and uses the modified AES algorithm to complete the encryption process. The technology is based on simulation verification, including pixel correlation, histograms, differential attacks, noise attacks, information entropy, key sensitivity, and space. The results demonstrate a remarkable encryption effect. Compared with other improved AES algorithms, this algorithm has the advantages of the original AES algorithm and improves the ability to resist correlation attacks.     

Vectorization,threading, and cache‐blocking considerations for hydrocodes on emerging architectures

The computational efficiency of existing hydrocodes is expected to suffer as computer architectures advance beyond the traditional parallel central processing unit (CPU) model 1 . Concerning new computer architectures, sources of relative performance degradation might include reduced memory bandwidth per core, increased resource contention due to concurrency, increased single instruction, multiple data (SIMD) length, and increasingly complex memory hierarchies. Concerning existing codes, any performance degradation will be influenced by a lack of attention to performance in their design and implementation. This work reports on considerations for improving computational performance in preparation for current and expected changes to computer architecture. The algorithms studied will include increasingly complex prototypes for radiation hydrodynamics codes, such as gradient routines and diffusion matrix assembly (e.g., in 1 - 6 ). The meshes considered for the algorithms are structured or unstructured meshes. The considerations applied for performance improvements are meant to be general in terms of architecture (not specifically graphical processing unit (GPUs) or multi‐core machines, for example) and include techniques for vectorization, threading, tiling, and cache blocking. Out of a survey of optimization techniques on applications such as diffusion and hydrodynamics, we make general recommendations with a view toward making these techniques conceptually accessible to the applications code developer. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.