Carbon nanotubes/magnetite hybrids prepared by a facile synthesis process and their magnetic properties

In this paper, a facile synthesis process is proposed to prepare multiwalled carbon nanotubes/magnetite (MWCNTs/Fe3O4) hybrids. The process involves two steps: (1) water-soluble CNTs are synthesized by one-pot modi. cation using potassium persulfate (KPS) as oxidant. (2) Fe3O4 is assembled along the treated CNTs by employing a facile hydrothermal process with the presence of hydrazine hydrate as the mineralizer. The treated CNTs can be easily dispersed in aqueous solvent. Moreover, X-ray photoelectron spectroscopy (XPS) analysis reveals that several functional groups such as potassium carboxylate (-COOK), carbonyl (-C=O) and hydroxyl (-C-OH) groups are formed on the nanotube surfaces. The MWCNTs/Fe3O4 hybrids are characterized with respect to crystal structure, morphology, element composition and magnetic property by X-ray diffraction (XRD), transmission electron microscopy (TEM), XPS and superconducting quantum interference device (SQUID) magnetometer. XRD and TEM results show that the Fe3O4 nanoparticles with diameter in the range of 20-60 nm were firmly assembled on the nanotube surface. The magnetic property investigation indicated that the CNTs/Fe3O4 hybrids exhibit a ferromagnetic behavior and possess a saturation magnetization of 32.2 emu/g. Further investigation indicates that the size of assembled Fe3O4 nanoparticles can be turned by varying experiment factors. Moreover, a probable growth mechanism for the preparation of CNTs/Fe3O4 hybrids was discussed.ArticleAPPLIED SURFACE SCIENCE. 255(20):8676-8681 (2009)journal articl

One-step preparation of water-soluble single-walled carbon nanotubes

A novel one-step process using potassium persulfate (KPS) as oxidant is proposed in this paper to prepare water-soluble single-walled carbon nanotubes (SWNTs). The process without the need for organic solvents and acids is a low-cost, eco-friendly, facile method. Morphology observation by atomic force microscopy (AFM) indicates that the KPS-treated SWNTs were effectively debundled without obvious shortening in their length. The functional groups and thermal stability of the treated SWNTs were analyzed by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). XPS results show that several functional groups such as potassium carboxylate (-COOK), carbonyl (-C=O) and hydroxyl (-C-OH) groups were formed on the surfaces of the SWNTs, while the TGA results reveal that the quantity of the functional groups can reach to approximately 20%.ArticleAPPLIED SURFACE SCIENCE. 255(15):7095-7099 (2009)journal articl

Synthesis and Mechanical Properties of Polybenzimidazole Nanocomposites Reinforced by Vapor Grown Carbon Nanofibers

This is a preprint of an article published in Polymer Composites. 31(3):491-496 (2010) JOHN WILEY & SONS INC URL: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1548-0569Polybenzimidazole (PBI) nanocomposites containing 0.5-5 wt% vapor grown carbon nanofibers (VGNFs) were successfully synthesized by solvent evaporation method. Fracture morphology examination confirmed the uniform dispersion of VGNFs in the matrix. The mechanical properties of neat PBI and the nanocomposites were systematically measured by tensile test, dynamic mechanical analysis (DMA), hardness measurement, and friction test. Tensile tests revealed that Young's modulus increased by about 43.7% at 2 wt% VGNFs loading, and further modulus growth was observed at higher filler loadings. DMA studies showed that the nanocomposites have higher storage modulus than neat PBI in the temperature range of 30-350 degrees C, holding storage modulus larger than 1.54 GPa below 300 degrees C. Outstanding improvement of hardness was achieved for PBI upon incorporating 2 wt% of VGNFs. The results of friction test showed that coefficient of friction of PBI nanocomposites decreased with VGNFs content compared with neat PBI.ArticlePOLYMER COMPOSITES. 31(3):491-496 (2010)journal articl

2021 Taxonomic update of phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales.

Correction to: 2021 Taxonomic update of phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales. Archives of Virology (2021) 166:3567–3579. https://doi.org/10.1007/s00705-021-05266-wIn March 2021, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. The phylum was expanded by four families (Aliusviridae, Crepuscuviridae, Myriaviridae, and Natareviridae), three subfamilies (Alpharhabdovirinae, Betarhabdovirinae, and Gammarhabdovirinae), 42 genera, and 200 species. Thirty-nine species were renamed and/or moved and seven species were abolished. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.This work was supported in part through Laulima Government Solutions, LLC prime contract with the US National Institute of Allergy and Infectious Diseases (NIAID) under Contract No. HHSN272201800013C. J.H.K. performed this work as an employee of Tunnell Government Services (TGS), a subcontractor of Laulima Government Solutions, LLC under Contract No. HHSN272201800013C. This work was also supported in part with federal funds from the National Cancer Institute (NCI), National Institutes of Health (NIH), under Contract No. 75N91019D00024, Task Order No. 75N91019F00130 to I.C., who was supported by the Clinical Monitoring Research Program Directorate, Frederick National Lab for Cancer Research. This work was also funded in part by Contract No. HSHQDC-15-C-00064 awarded by DHS S&T for the management and operation of The National Biodefense Analysis and Countermeasures Center, a federally funded research and development center operated by the Battelle National Biodefense Institute (V.W.); and NIH contract HHSN272201000040I/HHSN27200004/D04 and grant R24AI120942 (N.V., R.B.T.). S.S. acknowledges partial support from the Special Research Initiative of Mississippi Agricultural and Forestry Experiment Station (MAFES), Mississippi State University, and the National Institute of Food and Agriculture, US Department of Agriculture, Hatch Project 1021494. Part of this work was supported by the Francis Crick Institute which receives its core funding from Cancer Research UK (FC001030), the UK Medical Research Council (FC001030), and the Wellcome Trust (FC001030).S

2021 Taxonomic update of phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales.

In March 2021, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. The phylum was expanded by four families (Aliusviridae, Crepuscuviridae, Myriaviridae, and Natareviridae), three subfamilies (Alpharhabdovirinae, Betarhabdovirinae, and Gammarhabdovirinae), 42 genera, and 200 species. Thirty-nine species were renamed and/or moved and seven species were abolished. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV

An Enhanced Replica Selection Approach Based on Distance Constraint in ICN

Fifth generation (5G) networks have a high requirement for low latency of data delivery. Information-centric networking (ICN) adopts the paradigm of separation of the identifier and locator. It is efficient in content distribution by supporting in-network caching and has the potential to satisfy the low latency requirement in 5G. Replica selection is a key problem to retrieving content in ICN. Prior research usually utilizes the nearest replica. However, using the nearest replica cannot guarantee the smallest content download delay. To exploit in-network caching better, we propose an enhanced replica selection approach, called ERS. ERS first uses a distance-constrained-based name resolution system to discover the nearby replicas. Then, the most appropriate replica is chosen according to a local state table that maintains the state of replica nodes within a limited domain. In addition to network distance and replica node load, ERS innovatively introduces the path congestion degree between requester and replica nodes to assist replica selection. With extensive simulations, the proposed approach shows better performance than the state-of-the-art methods in terms of average content download delay. Finally, the overhead of the proposed method is analyzed

Two-Level Congestion Control Mechanism (2LCCM) for Information-Centric Networking

As an emerging network architecture, Information-Centric Networking (ICN) is considered to have the potential to meet the new requirements of the Fifth Generation (5G) networks. ICN uses a name decoupled from location to identify content, supports the in-network caching technology, and adopts a receiver-driven model for data transmission. Existing ICN congestion control mechanisms usually first select a nearby replica by opportunistic cache-hits and then insist on adjusting the transmission rate regardless of the congestion state, which cannot fully utilize the characteristics of ICN to improve the performance of data transmission. To solve this problem, this paper proposes a two-level congestion control mechanism, called 2LCCM. It switches the replica location based on a node state table to avoid congestion paths when heavy congestion happens. This 2LCCM mechanism also uses a receiver-driven congestion control algorithm to adjust the request sending rate, in order to avoid link congestion under light congestion. In this paper, the design and implementation of the proposed mechanism are described in detail, and the experimental results show that 2LCCM can effectively reduce the transmission delay when heavy congestion occurs, and the bandwidth-delay product-based congestion control algorithm has better transmission performance compared with a loss-based algorithm

Enhanced Thermal Insulation of the Hollow Glass Microsphere/Glass Fiber Fabric Textile Composite Material

Glass fiber fabrics/hollow glass microspheres (HGM)–waterborne polyurethane (WPU) textile composites were prepared using glass fiber, WPU, and HGM as skeleton material, binder, and insulation filler, respectively, to study the effect of HGM on the thermal insulation performance of glass fiber fabrics. Scanning electron microscopy, Instron 3367 tensile test instrument, thermal constant analysis, and infrared thermal imaging were used to determine the cross-sectional morphology, mechanical property, thermal conductivity, and thermal insulation property, respectively, of the developed materials. The results show that the addition of HGM mixed in WPU significantly enhanced thermal insulation performance of the textile composite with the reduction of thermal conductivity of 45.2% when the volume ratio of HGM to WPU is 0.8 compared with that of material without HGM. The composite can achieve the thermal insulation effect with a temperature difference of 17.74 °C at the temperature field of 70 °C. Meanwhile, the tensile strength of the composite is improved from 14.16 to 22.14 MPa. With these results, it is confirmed that designing hollow glass microspheres (HGM) is an effective way to develop and enhance the high performance of insulation materials with an obvious lightweight of the bulk density reaching about 50%

Interfacial Adhesion and Mechanical Properties of PET Fabric/PVC Composites Enhanced by SiO₂/Tributyl Citrate Hybrid Sizing

Poly(ethylene terephthalate) (PET) fabric-reinforced polyvinyl chloride (PVC) composites have a wide range of applications, but the interface bonding of PET fabric/PVC composites has remained a challenge. In this work, a new in-situ SiO2/tributyl citrate sizing agent was synthesized according to the principle of “similar compatibility.„ The developed sizing agent was used as a PET surface modifier to enhance the interfacial performance of PET fabric/PVC composites. The morphology and structure of the PET filaments, the wettability and tensile properties of the PET fabric, the interfacial adhesion, and the tensile and tearing properties of the PET fabric/PVC composites were investigated. Experimental results showed that many SiO2 nanoparticles were scattered on the surface of the modified PET filaments. Moreover, the surface roughness of the modified PET filaments remarkably increased in comparison with that of the untreated PET filaments. The contact angle of the modified PET filaments was also smaller than that of the untreated ones. The peeling strength of the modified PET fabrics/PVC composites was 0.663 N/mm, which increased by 62.50% in comparison with the peeling strength of the untreated ones (0.408 N/mm). This work provides a new approach to the surface modification of PET and improves the properties of PET fabric/PVC composites