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The recent progress in fibrous triboelectric nanogenerators (F-TENGs) is comprehensively introduced, with a special focus on their different fabrication techniques.

Wearable sensors with conductive polymer as the sensing material exhibit the combined advantages including comfortable attachment above epidermis, regulable configurations, and cost‐effective fabrication. It is highly desired to fabricate the conductive polymer‐based strain sensor that can precisely detect all the human physiological information. In this paper, we report a high‐performance strain sensor with the H2SO4 doped poly (3,4‐ethylenedioxythiophene):poly(4‐styrenesulfonate) (PEDOT:PSS) sensing network. This sensor exhibits comprehensive properties integrating high sensitivity (gauge factor up to 32), excellent stability (> 2000 cycles), and wide strain range detectability (0.1% to 70% strain). This sensor is attractive and promising for the practical full‐range detection of human physiological information from subtle vital signs to large human motions.

Graphene oxide (GO) is a unique two-dimensional (2D) material with interesting physical/chemical properties. GO can be considered as a 2D amphiphilic conjugated polymer, consisting of hydrophilic oxygenated groups and hydrophobic conjugated graphitic domains. The diverse chemical groups endow GO with high chemical activity to react with other molecules and form new species with graphitic framework. In addition, the amphiphilic properties of GO sheets provide them the abilities to self-assemble into three-dimensional (3D) structure or reduced GO (rGO) gels with porous microstructures. The precondition of these promising properties of GO is its excellent solution-like dispersibility in aqueous or nonaqueous media. These liquid media facilitate the exfoliation of GO into single-layer sheets and provide the exfoliated GO sheets with specific chemical environment for functionalization and/or processing. Therefore, it is essential to understand the solution-based chemical behaviour of GO, which is important for better application of GO. In this review, we outline the solution-based chemistry of GO mainly in terms of molecular structure, dispersibility in solvents, solution properties and related processing of GO sheets. This review aims to systematically present physical/chemical behaviours of GO in solvents including aqueous and nonaqueous solvents, which is helpful for better understanding and application of GO materials.

In this study, a novel flame retardant (PMrG) was developed by self-assembling melamine and phytic acid (PA) onto rGO, and then applying it to the improvement of the flame resistance of PLA. PMrG simultaneously decreases the peak heat release rate (pHRR) and the total heat release (THR) of the composite during combustion, and enhances the LOI value and the time to ignition (TTI), thus significantly improving the flame retardancy of the composite. The flame retardant mechanism of the PMrG is also investigated. On one hand, the dehydration of PA and the decomposition of melamine in PMrG generate non-flammable volatiles, such as H2O and NH3, which dilute the oxygen concentration around the combustion front of the composite. On the other hand, the rGO, melamine, and PA components in PMrG create a synergistic effect in promoting the formation of a compact char layer during the combustion, which plays a barrier role and effectively suppresses the release of heat and smoke. In addition, the PMrGs in PLA exert a positive effect on the crystallization of the PLA matrix, thus playing the role of nucleation agent.

Significant improvement in the fire resistance of polyethylene terephthalate (PET) while ensuring its mechanical properties is a tremendous challenge. A novel flame retardant (GO-HCCP, graphene oxide-hexachlorocyclotriphosphazene) was synthesized by nucleophilic substitution of the graphene oxide (GO) and hexachlorocyclotriphosphazene (HCCP) and then applied in PET by an in situ polymerization technique. The scanning electron microscope (SEM) showed a better dispersion of GO-HCCP than GO in the PET matrix. The char yield at 700 °C increased by 32.5% with the addition of GO-HCCP. Moreover, the peak heat release rate (pHRR), peak smoke produce rate (pSPR)and carbon monoxide production (COP)values significantly decreased by 26.0%, 16.7% and 37.5%, respectively, which indicates the outstanding fire and smoke suppression of GO-HCCP. In addition, the composites exhibited higher elastic modulus and tensile strength without compromising the toughness of PET matrix. These significantly reduced fire hazards properties are mainly attributed to the catalytic carbonation of HCCP and the barrier effect of GO. Thus, PET composites with good flame-retardant and mechanical properties were prepared, which provides a new strategy for further flame retardant PET preparation.

Avian Tembusu virus (TMUV) is a newly emerging avian pathogenic flavivirus that spreads rapidly, has an expanding host range and undergoes cross-species transmission. Our previous study identified avian monocytes/macrophages as the key targets of TMUV infection, since the infection of host monocytes/macrophages was crucial for the replication, transmission, and pathogenesis of TMUV. The polarization of host macrophages determines the functional phenotypes of macrophages; however, the effect of TMUV infection on macrophage polarization remains unclear. Here, we analysed the expression spectra of the marker genes of macrophage polarization upon TMUV infection in the HD11 chicken macrophage cell line and primary monocytes/macrophages isolated from the peripheral blood of specific pathogen-free (SPF) chickens and ducks. We found that viral replication mainly induced M1 marker genes and triggered nitric oxide (NO) release at different levels, suggesting that TMUV infection led mainly to host macrophages polarizing into the classically activated (M1) type. The NO that was increased upon infection did not function as an antiviral agent against TMUV, since the replication of TMUV in HD11 cells was not affected by the addition of an organic NO donor. Furthermore, upon TMUV infection, polarized HD11 cells exhibited increased migration but reduced phagocytosis, as evidenced by scratch assay and neutral red uptake assay, respectively. Our present study characterized the polarization of host monocytes/macrophages upon TMUV infection, which may lay a foundation for further research on the immune escape mechanism and pathogenic mechanism of TMUV.

The hierarchical formation of self-assembling peptide-based hydrogels (SAPHs) starts from peptide to nanofibers, following with the entanglement into hydrogels with nanofibrous network. Such characteristic structure and extraordinary biocompatibility, and the peptide components endow the SAPHs with diverse applications in biotechnological field. Therefore, the thorough comprehension of SAPHs is significant to broadening their application. In this review, fabrication, properties, and biological applications of the SAPHs are introduced, and the factors influencing the synthesis process as well as the properties of the SAPHs products are also systematically explained. Meanwhile, we conclude the problems to be solved and provide our perspective to the future development of SAPHs in the biotechnology.

International audience; It is common practice to blend polymers to obtain high-performance polymer materials for new applications. Thermoplastic vulcanizates (TPVs), consisting of a high content of crosslinked rubber as a dispersed phase and a low content of thermoplastic as a continuous phase, are usually prepared by pre-blending rubber and plastic phases followed by dynamic vulcanization. They are a special class of high performance thermoplastic elastomers (TPEs) as they combine both the excellent elasticity and mechanical properties of crosslinked rubbers and good processability and recyclability of thermoplastics. As such, in the recent decades they have attracted much attention and have become the fastest growing elastomers to replace unrecyclable thermoset rubbers. This review focuses on recent progresses in TPVs, and more specifically on the following issues: (1) preparation methods of TPVs, (2) mechanisms of formation of the microstructure of TPVs; (3) relationships between the microstructure and properties, (4) review of various types of TPVs, including general TPVs, special TPVs, bio-based TPVs, and TPVs-based nanocomposites, (5) future challenges on TPVs.

Wearable sensors that can precisely detect vital signs are highly desirable for monitoring personal health conditions and medical diagnosis. In this paper, we report an ultrasensitive strain sensor consisting of a 150 nm thick highly conductive dimethylsulfoxide-doped poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) sensing layer and an elastic fluorosilicone rubber substrate. This sensor exhibits a high sensitivity at small strains (e.g., gauge factor at 0.6% strain = 280), low limit of detection (

Triboelectric nanogenerator (TENG) can convert mechanical energy into electricity, thus realizing the development of a new type of self-powered wearable sensors, which generate electric signals directly upon mechanical stimuli. On another hand, good stretchability is also an essential character of the wearable sensors to guarantee deformation consistence with the human body. In this work, a fibrous stretchable TENG-based sensor (FS-TENG sensor) with core-sheath structure is fabricated and applied in physiological monitoring. The output open-circuit voltage and shout-circuit current of FS-TENG sensor can reach nearly 10 V and 0.6 μA, respectively. The elastic substrates and stretchable electrodes provide the FS-TENG sensor with good resilience, and the output voltage of the sensor keeps stable under 60% strain extension, demonstrating the stability of the sensor at large deformation. Meanwhile, the FS-TENG sensor can detect ultralow pressure down to 0.02 N and achieve 26.75 V N−1 in low pressure, showing its ultralow detection limit and outstanding sensitivity to external force. Taking advantage of the excellent sensing performance of the FS-TENG sensor, we applied it in the human motions monitoring, including large movements (joints bending and step) and subtle vital signs (pulse, phonation, and expression). Moreover, a tactile sensor array with 3 × 3 pixels is fabricated by weaving 6 FS-TENG sensors to realize the pressure distribution recognition.

Polyolefin elastomer (POE)/polypropylene (PP) thermoplastic vulcanizates (TPVs) is considered to be a better alternative to commercial ethylene-propylene-diene monomer (EPDM)/PP TPVs owing to its better overall performance and low-cost. In this study, we deeply studied the morphology development of POE/PP blends during dynamic vulcanization (DV) and its influencing factors such as the degree of crosslinking, crosslinking rate and shear rate. The results show that POE/PP TPVs exhibits smaller rubber nanoparticles (RNPs) and their agglomerates than that of EPDM/PP TPVs because of the better compatibility between POE and PP. The morphology development during DV of POE/PP TPVs is dominated by the formation and agglomeration of POE RNPs caused by the combined effect of dynamical in-situ crosslinking and the shear-induced break-up of POE phase. Higher degree of crosslinking, higher shear rate and moderate crosslinking rate of POE phase facilitate the rapid formation of smaller RNPs and RNPs agglomerates, and accelerate the occurrence of faster phase inversion. This study provides guidance for the preparation of high performance POE/PP TPVs by controlling the microstructure.

Although therapeutics targeting viral metabolic processes have been considered as promising strategies to treat herpesvirus infection, the metabolic requirements of gallid alphaherpesvirus 1 (ILTV), which is economically important to the poultry industry worldwide, remain largely unknown. Using the ILTV-susceptible but nonpermissive chicken cell line DF-1 and the ILTV-permissive chicken cell line LMH as models, the present study explored the metabolic requirements of ILTV by global transcriptome analysis and metabolome assays of ILTV infected cell lines in combination with a set of functional validations. The extensive metabolic exploration demonstrated that ILTV infection tended to promote a metabolic shift from glycolysis to fatty acid (FA) and nucleotide biosynthesis and utilizes glutamine independently of glutaminolysis, without significant general effect on the TCA cycle. In addition, different metabolic pathways were found to be required for distinct stages of ILTV replication. Glucose and glutamine were required for the transcription of viral immediate early gene ICP4 and subsequent steps of viral replication. However, FA synthesis was essential for assembly but not required for other upstream steps of ILTV replication. Moreover, the metabolic requirements of ILTV infection revealed in chicken cell lines were further validated in chicken primary cells isolated from chicken embryo kidneys and chicken embryo livers. The present study, to the best of our knowledge, provides the first global metabolic profile of animal herpesviruses and illustrates the main characteristics of the metabolic program of ILTV., Author summary Virus-host metabolic interaction is a promising target for antiviral therapeutics. Explorations of viral-induced shifts of host metabolism could reveal substrates that are uniquely required at high levels for viral replication and have been conducted for many virus species in the last decade. Herpesviruses are commonly treated with nucleotide analogs in the clinic. However, recent metabolomics studies suggest that different herpesvirus species can execute distinct metabolic programs in host cells despite their high conservation of biological characteristics. To understand why herpesviruses have evolved to alter different metabolic processes in host cells and refine the antiviral treatments by targeting more species-specific metabolic requirements, metabolomic explorations of more herpesvirus species are needed. However, comprehensive exploration of virus-host metabolic interaction has only been limited to a few human herpesviruses. Gallid alphaherpesvirus 1 (ILTV), an economically important alphaherpesvirus to the poultry industry worldwide, is thought to be an ancient example of alphaherpesviruses. Here we reveal the global metabolic requirements of ILTV and highlight the common and unique metabolic characteristics of ILTV by comparing with the known global metabolic profiles of several human herpesviruses. Our study may increase current understanding of herpesvirus-host metabolic interplay and inspire further studies in this direction.

Avian Tembusu virus (TMUV) is a newly emerging avian pathogenic flavivirus in China and Southeast Asia with features of rapid spread, an expanding host range, and cross-species transmission. The mechanisms of its infection and pathogenesis remain largely unclear. Here, we investigated the tropism of this arbovirus in peripheral blood mononuclear cells of specific-pathogen-free (SPF) ducks and SPF chickens and identified monocytes/macrophages as the key targets of TMUV infection. In vivo studies in SPF ducks and SPF chickens with monocyte/macrophage clearance demonstrated that the infection of monocytes/macrophages was crucial for viral replication, transmission, and pathogenesis. Further genome-wide transcriptome analyses of TMUV-infected chicken macrophages revealed that host antiviral innate immune barriers were the major targets of TMUV in macrophages. Despite the activation of major pattern recognition receptor signaling, the inductions of alpha interferon (IFN-α) and IFN-β were blocked by TMUV infection on transcription and translation levels, respectively. Meanwhile, TMUV inhibited host redox responses by repressing the transcription of genes encoding NADPH oxidase subunits and promoting Nrf2-mediated antioxidant responses. The recovery of either of the above-mentioned innate immune barriers was sufficient to suppress TMUV infection. Collectively, we identify an essential step of TMUV infection and reveal extensive subversion of host antiviral innate immune responses. IMPORTANCE Mosquito-borne flaviviruses include a group of pathogenic viruses that cause serious diseases in humans and animals, including dengue, West Nile, and Japanese encephalitis viruses. These flaviviruses are zoonotic and use animals, including birds, as amplifying and reservoir hosts. Avian Tembusu virus (TMUV) is an emerging mosquito-borne flavivirus that is pathogenic for many avian species and can infect cells derived from mammals and humans in vitro. Although not currently pathogenic for primates, the infection of duck industry workers and the potential risk of TMUV infection in immunocompromised individuals have been highlighted. Thus, the prevention of TMUV in flocks is important for both avian and mammalian health. Our study reveals the escape of TMUV from the first line of the host defense system in the arthropod-borne transmission route of arboviruses, possibly helping to extend our understanding of flavivirus infection in birds and refine the design of anti-TMUV therapeutics.

Viral spread is considered a promising target for antiviral therapeutics, but the associated mechanisms remain unclear for gallid alpha herpesvirus 1 (ILTV). We previously identified proto-oncogene tyrosine-protein kinase Src (Src) as a crucial host determinant of ILTV infection. The present study revealed accelerated spread of ILTV upon Src inhibition. This phenomenon was independent of either viral replication or the proliferation of infected cells and could not be compromised by neutralizing antibody. Neither extracellular vesicles nor the direct cytosol-to-cytosol connections between adjacent cells contributed to the enhanced spread of ILTV upon Src inhibition. Further genome-wide transcriptional profile analyses in combination with functional validation identified fatty acid metabolism as an essential molecular event during modulation of the intercellular spread and subsequent cytopathic effect of ILTV by Src. Overall, these data suggest that Src controls the cell-to-cell spread of ILTV in a cellular fatty acid metabolism-dependent manner, which determines the virus's cytopathic effect.

The PP multilayer film/foams prepared by the multilayer coextrusion technique possess a unique solid/porous alternating horizontal architecture, in which the film layers can effectively suppress the premature rupture of cells in foam layers. This paper introduces a strong and lightweight layered cellular structure developed through optimized uniaxial drawing of the coextruded PP multilayer film/foams. Moreover, systematic study reveals the effects of orientation on the structure and properties of the oriented PP multilayer film/foams. Formation of subcellular interconnected porous structure decreases the bulk density with increasing draw ratio (DR) up to DR = 3.5. In addition, strain induced increase in the orientation of α crystals and crystallinity of PP during uniaxial drawing improves the tensile strength and modulus of the oriented multilayer film/foam significantly. The oriented PP multilayer film/foam with the lowest density and improved tensile properties can be obtained at DR = 4 at the optimized...

Thermoplastic vulcanizates (TPVs), as a special class of high-performance thermoplastic elastomers (TPEs), consist of a high content (60–80 wt%) of crosslinked rubber particles as the dispersed phase and a low content of a thermoplastic as the matrix. In this study, inspired by the special microstructure of TPVs, we prepared carbon nanotubes (CNTs)/TPV dielectric elastomer composites with a high dielectric constant (k) and low dielectric loss by constructing a dual network formed by rubber and CNTs. The rubber network was formed by a high content of agglomerates of rubber nanoparticles in the TPVs, which simultaneously promoted the formation of a CNTs network at a low content of CNTs in the matrix, to increase the value of k, and hindered the direct connection of CNTs with one another, to decrease the dielectric loss. As a result, the CNTs/TPV composites simultaneously possessed a high value of k and low dielectric loss. Moreover, the elasticity of the composites was improved by the CNTs because of the nanosprings of CNTs. This study provides a new simple and effective strategy for preparing a high-performance dielectric elastomer with a high value of k, low dielectric loss, good mechanical properties, high elasticity, high processability and easy recyclability.

Enzyme-based hybrid nanoflowers (EHNFs) provide a way to immobilize the enzymes without harsh conditions and mass transfer limitations, as well as promote the performances of the enzymes. This kind of immobilization attracted a considerable interest in further developing the application of enzymatic reactions. Therefore, the comprehensive understanding of the preparation, micro-structure, and catalytic behavior of EHNFs is critical for their better application. In this review, a wide variety of EHNFs in terms of synthesis, categories, morphologies and their applications in biocatalytic, biomedical, environment and bioenergy are introduced. Additionally, we discuss the future trends and perspectives of EHNFs in order to offer rational suggestions for the future researches and developments of these promising biocatalysts.

It is challenging to construct exquisite microstructures for integrating extraordinary sensitivity, wide strain range detectability, low hysteresis, good linearity, and excellent reliability and stability in a single type of strain sensor. In this paper, we report a high-performance fibrous strain sensor with ultrahigh sensitivity (gauge factor up to 350), wide sensing range (0.1% to 150% strain), low hysteresis, good linearity over a large strain range (up to 50%), and excellent reliability and stability (>2000 cycles). Our fibrous strain sensor exhibits superior comprehensive properties to previous strain sensors, attributed to its hierarchical microstructure composed of twisted polyurethane fibers and microcracked poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) sensing layer on each fiber, bridged by carbon nanotube agglomerates. This sensor is attractive and promising for the full-range detection of human motion from subtle deformations to large movements. In addition, the spatial extensional strain distribution of human skin can also be detected by the sensing fabric woven by this fibrous sensor due to its knittability.

In OFDMA-based systems, inter-cell interference (ICI) is a major limiting factor for system throughput performance in multi-cell deployment. Especially for the users located at the cell edge, it has been a challenging task to enhance their data rates while maintaining a high spectral efficiency for the overall system. This letter proposes a new frequency reuse and allocation scheme, whereby interference from the first tier adjacent cells to the cell-edge region is eliminated so that the signal to interference plus noise radio (SINR) at the cell edge is significantly increased. The proposed scheme allows full frequency reuse for wireless networks. It is proven that given the same channel condition and user position the proposed scheme is able to achieve a higher SINR in the network, compared with the popular soft frequency reuse (SFR) scheme. Numerical results show that the cell edge spectral efficiency and the overall cell spectral efficiency can be improved significantly, compared with the conventional full reuse (FR) scheme and the SFR scheme. Furthermore, we point out that unlike the SFR scheme which requires degrading the spectral efficiency of the cell-center users (CCUs) in order to achieve a better interference pattern for the cell-edge users (CEUs), there exists an operation region in the proposed scheme where gains of spectral efficiency can be achieved for both the CEUs and the CCUs simultaneously.

Thermoplastic vulcanizates (TPVs) have attracted considerable attention as typical “green” polymers in recent years and have been widely used in industry because they combine the excellent resilien...

In this work, zinc dimethacrylate (ZDMA) and 2-sulfur-benzimidazole (MB)/N-4(phenyl–phenyl)-maleimide (MC) were simultaneously used as synergistic antioxidants to improve the thermo-oxidative aging resistance of peroxide vulcanized ethylene-propylene-diene monomer (EPDM) for its application at high temperature. For comparison purpose, the control sample without antioxidants, the traditional antioxidant package, the combined antioxidant MB/MC, and pure ZDMA were also investigated. The results showed that the crosslinking density of EPDM was only slightly decreased before aging by using the combined antioxidant MB/MC/ZDMA, and the increase in crosslinking density was much less than other antioxidants at the same aging time, indicating the largely improved aging resistance of EPDM. As a result, the change in mechanical properties was the lowest for EPDM with the combined antioxidant MB/MC/ZDMA at high temperature. Meanwhile, the results from structure analysis showed that the degree of oxidation of EPDM was much lower than other systems after aging at 180 °C for 216 h by using the combined antioxidant MB/MC/ZDMA. In addition, the surfaces of EPDM samples with MB/MC/ZDMA as synergistic antioxidants or the combined antioxidant MB/MC were still smooth after aging at 180 °C for 216 h, whereas severe cracks occurred for other antioxidative systems. These results suggest the good thermo-oxidative aging resistance of the synergistic antioxidant MB/MC/ZDMA. Finally, the synergistic antioxidative mechanism of MB/MC/ZDMA was carefully discussed.

We previously reported that the dispersed rubber microparticles in ethylene-propylene-diene monomer (EPDM)/polypropylene (PP) thermoplastic vulcanizates (TPVs) are actually agglomerates of rubber nanoparticles. In this study, based on this new understanding of the microstructure of TPV, we further revealed the microstructure-properties relationship of EPDM/PP TPV during dynamic vulcanization, especially the effect of the size of rubber nanoparticle agglomerates (dn), the thicknesses of PP ligaments (IDpoly) and the rubber network on the properties of EPDM/PP TPV. We were able to simultaneously obtain a high tensile strength, elongation at break, elastic modulus, and elasticity for the EPDM/PP TPV by the achievement of a smaller dn, a thinner IDpoly and a denser rubber network. Interestingly, the effect of dn and IDpoly on the elastic modulus of EPDM/PP TPV composed of rubber nanoparticle agglomerates is different from that of EPDM/PP TPVs composed of rubber microparticles reported previously. The deformation behavior of the TPVs during stretching was studied to understand the mechanism for the achievement of good mechanical properties. Interestingly, the rubber nanoparticle agglomerates are oriented along the tensile direction during stretching. The TPV samples with smaller and more numerous rubber nanoparticle agglomerates can slow down the development of voids and cracks more effectively, thus leading to increase in tensile strength and elongation at break of the EPDM/PP TPV.

We successfully prepared bromo-isobutylene–isoprene rubber (BIIR)/polyamide 12 (PA 12) thermoplastic vulcanizate (TPV) by dynamic vulcanization (DV), and studied the microstructure and properties of BIIR/PA 12 TPV toward recyclable inner liners for green tires, to reduce fuel consumption and carbon emissions. The as-prepared BIIR/PA 12 TPV exhibits good mechanical properties, good elasticity, easy processability and good gas barrier properties. More importantly, our BIIR/PA 12 TPV still exhibits good properties after recycling several times. The mechanism for the formation of the phase morphology and morphological evolution during dynamic vulcanization, and the microstructure–property relationship of BIIR/PA 12 TPV were thoroughly studied to provide guidance for the preparation of high-performance BIIR/PA 12 TPVs toward tire inner liners. As the DV proceeded, the size of the dispersed BIIR particles and the thickness of the PA 12 ligaments decreased, leading to the strengthening of the rubber network. Although the rheological properties slightly deteriorated, the elasticity, the mechanical properties and the gas barrier properties of the TPVs were obviously improved as the DV proceeded.

We studied the microstructure, morphological evolution and the corresponding mechanism, and the properties of bromo-isobutylene-isoprene rubber (BIIR)/polypropylene (PP) thermoplastic vulcanizates (TPVs). Interestingly, a large number of single rubber nanoparticles were observed in the crosslinked BIIR/PP blends, ascribed to the improvement of compatibility between the BIIR and PP with increasing dynamic vulcanization (DV) time, as demonstrated by the increase in interfacial phase thickness and the decrease in the interfacial tension. Most of these single nanoparticles agglomerated as the DV proceeded, leading to the deterioration of the rubber network. Another interesting observation was that the size of rubber agglomerate decreased as the DV proceeded, leading to the strengthening of the rubber network. Importantly, the as-prepared BIIR/PP TPV exhibits good processability, high elasticity and good mechanical property. The relationship between the unique morphology and properties were studied. Our study provides guidance for the preparation of high-performance BIIR/PP TPV for its industrial applications such as medical bottle stoppers.

Thermoplastic vulcanizates (TPVs) combine the excellent elasticity of conventional vulcanized rubbers and the easy processability and recyclability of thermoplastics. In this study, we successfully prepared novel heat and oil-resistant TPVs based on ethylene-vinyl acetate rubber (EVM) and poly(vinylidene fluoride) (PVDF) by dynamic vulcanization (DV). The phase morphology, morphological evolution, and the properties of the EVM/PVDF TPVs were studied, and the microstructure–property relationship during DV was revealed. Interestingly, a large number of EVM rubber nanoparticles are observed in the EVM/PVDF TPVs during DV, and these nanoparticles assemble into oriented EVM fibers and EVM bundles during DV. As the DV further proceeds, the oriented EVM fibers and EVM bundles agglomerate with one another more densely and further assemble into EVM spherulites, leading to an increase in the thickness of the PVDF ligaments and the deterioration of the rubber network. More importantly, our EVM/PVDF TPVs show good mechanical properties, high elasticity, good processability, excellent heat-and oil resistance, and good recyclability. This study provides guidance for the preparation of new TPVs that can replace the traditional thermosetting rubbers in automotive and oil pipeline areas.

In this study, the morphologies of three types of acrylonitrile-butadiene rubber (NBR)/polypropyl- ene (PP) thermoplastic vulcanizates (TPVs) (with an NBR/ PP blend ratio of 70/30) were compared. The TPVs were (1) an ultrafine fully vulcanized acrylonitrile-butadiene rubber (UFNBR)/PP TPV made by the mechanical blend- ing of UFNBR with PP, (2) a dynamically vulcanized NBR/PP TPV without the compatibilization of maleic an- hydride grafted polypropylene (MP) and amine-termi- nated butadiene-acrylonitrile copolymer (ATBN), and (3) a dynamically vulcanized NBR/PP TPVs with the compati- bilization of MP and ATBN. The influence of the compati- bility therein on the size of the dispersed vulcanized NBR particles and the crystallization behavior of the PP in the TPVs and the resultant properties are also discussed. As indicated by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calo- rimetry, polarizing microscopy, dynamic mechanical ther- mal analysis, and rheological and mechanical testing, the compatibility was significantly improved by the reac- tive compatibilization of MP and ATBN, which led to a uniform and fine morphology. The compatibilization increased the crystallization rate and reduced the size of the spherulites of PP. On the other hand, it was found that the dispersed vulcanized NBR particles lowered the degree of crystallinity. The better the compatibility of the blend was, the lower the degree of crystallinity and the storage modulus were, but the higher the loss factor and the processing viscosity were. All TPVs showed almost the same oil resistance, but the TPV prepared with reac- tive compatibilization had the best mechanical properties. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 124: 1999-2006, 2012

Silicone rubber microwave absorbing materials (RMAMs) based on ferrite as the major absorbent were prepared by the mechanical blending method. The determining factors for the complex permittivity, complex permeability, and reflectivity of RMAM were thoroughly investigated with various samples including different crystal structures of Ba-ferrite (M-type, W-type, and Y-type), the ferrite with doped elements (Ba, Sr), the materials' thickness, the combination ratio of ferrite and carbonyl iron. The effects of surface modification and loading amount of ferrite on the mechanical properties, processing performance, and absorbing property of RMAM were also assessed. The results show that W-type Ba-ferrite based RMAM exhibits better absorbing property at high frequencies (8–18 GHz) than the other two barium ferrites (M-type and Y-type) based ones, and the absorbing property of RMAM based on Sr-ferrite is best. As the thickness of RMAM and the amount of absorbents increase, the absorption peak moves toward low frequency, the absorption frequency bandwidth is narrowed, and the reflectivity first decreases and later increases. The optimum thickness is 1.5–1.7 mm, and the amount of ferrite is 450 parts per hundreds of rubber (phr). Surface modification of the absorbent with silane coupling agent could improve the mechanical properties and processing performance of RMAM. It is concluded that there will be a synergistic effect when carbonyl iron (CI) is used in combination with Sr-ferrite (Sr-W) in an appropriate proportion. When the total volume fraction of absorbents is 51%, the optimum ratio of Cl to Sr-W is 17:34, the absorption frequency bandwidth (

A novel side-pumped structure with microlens-free diode arrays and a lensduct was demonstrated. This structure is much more robust and simple than traditional approach of a microlens-conditioned diode arrays with a lensduct. A quasi-CW diode arrays side-pumped KD*P Q-switched Yb:YAG slab laser has been demonstrated. An output energy of ∼10 mJ/pulse with pulse width as short as ∼20ns is obtained at 1–10 Hz repetition rate. To our knowledge, this is the shortest pulse width of Electro-optic Q-switched laser output by using Yb:YAG as the gain medium.

Femtocells have become an attractive approach for operators to offer extended services on their licensed UMTS/LTE spectrum. They are typically deployed indoors to improve coverage and provide high data rates. Cellular operators benefit from reduced infrastructure and operational expenses for capacity upgrades and coverage improvements. As a drawback, femtocells may cause interference to other femtocells or to the macrocellular wireless network. The interference in the system strongly depends on the type of cell selection method, which decides if a given mobile station is allowed to get access to a certain macro or femto base station (BS). In this paper various cell selection methods for femto and macro user equipments (UE) together with their benefits and drawbacks are introduced and discussed. We report on the first results obtained by using different cell selection methods in LTE macro-/femtocell deployment scenarios.

Single carrier (SC) FDMA was agreed to be chosen for 3GPP-long term evolution (LTE) uplink. A recent discussed feature for boosting up bit rates in LTE uplink is to apply SDMA (space division multiple access) to enable users to communicate with the serving base station using the same frequency resource. This paper analyzes the achievable sum rate in SC-FDMA system uplink, where SDMA with frequency domain linear zero forcing equalizer is assumed for the users. Analytical results show that in general SDMA with SC-FDMA has inferior rate performance to that with OFDMA. Furthermore, a simple algorithm is proposed to find the group of users for SDMA transmission based on the wideband average spatial correlation. Significant performance improvement against fixed grouping is shown for 3GPP-LTE uplink scenarios.

In this paper we report on PAPR reduction techniques using DFT precoding at the user equipment transmitter as discussed in standardization for 3GPP-long-term-evolution (LTE) uplink. We propose to combine DFT precoding and frequency dependent scheduling, a so called a virtual multiuser DFT precoding technique, to achieve high spectral efficiency in moderate and high SNR condition. This technique enables flexible and efficient utilization of frequency resources. It also enables multiple service for users with different quality of service and error protection requirements. For cell edge users with low SNR, we show that DFT precoding with filtering similar to single carrier transmission with appropriate pulse shaping is a reasonable option to increase the cell edge throughput.

In 3GPP GERAN 1, the performance specification of dualantenna interference suppression techniques will be a subject of the Downlink Advanced Receiver Performance (DARP) phase II work item. In this study, we apply a filter-based single antenna interference suppression technique for downlink GSM 8PSK modulation assuming the terminal is equipped with two antennas. We evaluate the performance using a correlation-based spatial channel model and show the potential of suppressing the co-channel interference even for high correlation factors. Besides, a performance improvement can be observed if the phase angles of the correlation factors for the desired user and interferer are different in highly spatially correlated channels.