EPDM recycling assisted by γ-processing

The integration of waste ethylene–propylene–diene terpolymer (EPDM), containing carbon black into pristine EPDM can be achieved by γ-irradiation as a versatile procedure to process ethylene–propylene elastomers. The presence of acrylic acid in the material formulation allows the formation of intermolecular bridges by threefold increase in gel content. The possibility of achieving greater stability by the addition of acrylic acid in EPDM systems was analyzed. The start materials were EPDM containing 30 and 50 phr of EPDM powder loaded with 40 phr of carbon black aged by pre-exposure to electron beam irradiation. The advanced γ-irradiation exceeding 100 kGy represented the optimal radiation processing condition. Two procedures of chemiluminescence under isothermal and non-isothermal regimes for the evaluation of radiation stability were applied on γ-irradiated samples. The thermal strength of irradiated samples was characterized based on the radiolysis mechanism of EPDM. The variation in the activation energy required for the thermal oxidation of these samples and the modification in gel contents due to the gelation action of acrylic acid were presented for the validation of proposed recycling radiochemical technique. Charlesby–Pinner representation provided different values for the ratios between radiochemical yields of cross-linking and scission, proving that the presence of acrylic acid promoted the conversion of EPDM wastes into valuable materials.     

Mitochondrial Dysfunction and Chronic Inflammation in Polycystic Ovary Syndrome

Polycystic ovarian syndrome (PCOS) is the most common endocrine–metabolic disorder affecting a vast population worldwide; it is linked with anovulation, mitochondrial dysfunctions and hormonal disbalance. Mutations in mtDNA have been identified in PCOS patients and likely play an important role in PCOS aetiology and pathogenesis; however, their causative role in PCOS development requires further investigation. As a low-grade chronic inflammation disease, PCOS patients have permanently elevated levels of inflammatory markers (TNF-α, CRP, IL-6, IL-8, IL-18). In this review, we summarise recent data regarding the role of mtDNA mutations and mitochondrial malfunctions in PCOS pathogenesis. Furthermore, we discuss recent papers dedicated to the identification of novel biomarkers for early PCOS diagnosis. Finally, traditional and new mitochondria-targeted treatments are discussed. This review intends to emphasise the key role of oxidative stress and chronic inflammation in PCOS pathogenesis; however, the exact molecular mechanism is mostly unknown and requires further investigation.     

A Volatile Relationship: Profiling an Inter-Kingdom Dialogue Between two Plant Pathogens,Ralstonia Solanacearum and Aspergillus Flavus

Microbes in the rhizosphere have a suite of extracellular compounds, both primary and secondary, that communicate with other organisms in their immediate environment. Here, we describe a two-way volatile interaction between two widespread and economically important soil-borne pathogens of peanut, Aspergillus flavus and Ralstonia solanacearum, a fungus and bacterium, respectively. In response to A. flavus volatiles, R. solanacearum reduced production of the major virulence factor extracellular polysaccharide (EPS). In parallel, A. flavus responded to R. solanacearum volatiles by reducing conidia production, both on plates and on peanut seeds and by increasing aflatoxin production on peanut. Volatile profiling of these organisms using solid-phase micro-extraction gas chromatography mass spectroscopy (SPME-GCMS) provided a first glimpse at the compounds that may drive these interactions.     

Improvement of Mechanical Properties of Automotive Components Using Hot Stamping With Integrated Q-P Process

Cold forming of high strength materials is accompanied by an undesirable spring-back effect and therefore the automotive industry prefers to produce components from high strength steels by hot stamping.Hot deformation and cooling in a die are applied to obtain shaped components with martensitic microstructure and high yield strength and ultimate tensile strength.This article presents new applications of this forming technology by incorporating another innovative heat treatment by the Q-P process,which improves both strength and ductility of obtained structures at the same time.Ultimate strengths over 2000 MPa with ductility above 10% can be achieved by this processing.To test microstructure development,thin sheet was hot formed and a corresponding FEM simulation was created.This processing was applied to low alloyed AHS steel with 0.42% of carbon and with an alloying strategy based on Mn,Si and Cr.Martensitic microstructure with retained austenite was obtained by this processing with a strength of around 2000 MPa and ductility of 10%.     

MIS photodiode with an InAs-based tunnel-transparent oxide layer

Results of studying the possibilities of passivating InAs surfaces by ultrathin oxide films (～3 nm) in a glow-discharge plasma and producing tunnel MIS photodiodes on this basis are presented together with results of investigating the kinetics of oxidation and the chemical composition of oxide films formed. This is the first time when anhysteretic dependences of the capacitance on the bias are observed for InAs-based MIS structures at the liquid nitrogen temperature in a wide field range (from ?7 · 10⁶ to +5 · 10⁶ V/cm). MIS structures are IR-photosensitive in the current mode. The estimated values of detectability are D* = 2.6·10¹²–8.2·10¹² cm·Hz^1/2·W^?1 and D* = 1.5·10¹¹ cm·Hz^1/2·W^?1 at temperatures of 78 and 198 K, respectively. The ampere-watt sensitivity value at a temperature of 78 K is 0.98 A/W, and the quantum efficiency is 0.43 (with no antireflecting coating of the InAs substrate and sapphire window).     

Alternating Copolymers of Cyclopenta[2,1‐b;3,4‐b′]dithiophene and Thieno[3,4‐c]pyrrole‐4,6‐dione for High‐Performance Polymer Solar Cells

A series of alternating copolymers of cyclopenta[2,1‐b;3,4‐b′]dithiophene (CPDT) and thieno[3,4‐c]pyrrole‐4,6‐dione (TPD) have been prepared and characterized for polymer solar cell (PSC) applications. Different alkyl side chains, including butyl (Bu), hexyl (He), octyl (Oc), and 2‐ethylhexyl (EH), are introduced to the TPD unit in order to adjust the packing of the polymer chain in the solid state, while the hexyl side chain on the CPDT unit remains unchanged to simplify discussion. The polymers in this series have a simple main chain structure and can be synthesized easily, have a narrow band gap and a broad light absorption. The different alkyl chains on the TPD unit not only significantly influence the solubility and chain packing, but also fine tune the energy levels of the polymers. The polymers with Oc or EH group have lower HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energy levels, resulting higher open circuit voltages (V_oc) of the PSC devices. Power conversion efficiencies (PCEs) up to 5.5% and 6.4% are obtained from the devices of the Oc substituted polymer (PCPDTTPD‐Oc) with PC₆₁BM and PC₇₁BM, respectively. This side chain effect on the PSC performance is related to the formation of a fine bulk heterojunction structure of polymer and PCBM domains, as observed with atomic force microscopy.     

Promising antifungal effect of some Euro-Asiatic plants against dangerous pathogenic and toxinogenic fungi

BACKGROUND: Increasing evidence of fungicide‐resistant toxinogenic and pathogenic fungal species is obvious. Looking for new possibilities of antifungal treatment or sources of antifungal substances is a major problem. Some medicinal plants exert strong antifungal properties and could be conveniently used as a promising alternative source for presently problematic antifungal treatment in many areas with respect to their natural origin. Methanol extracts of 46 medicinal plants from the Eurasian area were used in a screening assay for antifungal activity in this study. The growth inhibitory effect was tested against six significant pathogenic and toxinogenic fungal species: Fusarium oxysporum, F. verticillioides, Penicillium expansum, P. brevicompactum, Aspergillus flavus and A. fumigatus. RESULTS: For 14 plant species, the possibility of using them as natural fungicides was indicated. The extract from Grindelia camporum showed significant activity against all target fungal species. The most sensitive target fungus was the toxinogenic and human pathogenic species A. fumigatus. CONCLUSION: This study has identified 14 extracts of medicinal plants with a potential use as an antifungal treatment in various areas. One of them showed promising efficiency against all selected significant pathogenic and toxinogenic fungal species. Copyright © 2010 Society of Chemical Industry     

PBT blends with rigid polymer and elastomer inclusions: the effect of component type and reactivity on mechanical behaviour

The present study shows the potential of the poly(butylene terephthalate) (PBT) matrix to form ternary blends with well‐balanced properties, analogous to Polyamide 6 (PA6) systems with a very fine (<100 nm) separately dispersed rigid polymer (poly(styrene‐co‐maleic anhydride)) and elastomer (maleated ethylene‐propylene elastomer). The use in PBT blends of maleated components analogous to those in the PA6 systems was much less effective, due to the presence of larger particles. Enhancement of all properties, including toughness, was found in the case of a blend containing at least one component with epoxide groups, such as rigid styrene‐glycidyl methacrylate copolymer or elastomeric poly[(ethylene)‐co‐(methyl acrylate)‐co‐(glycidyl methacrylate)]. In this case, the reactive compatibilization of the epoxy‐group‐containing component caused refinement of particle size of the other component due to enhanced viscosity. As a result, more advantageous micromechanical behaviour of this ternary in comparison with the binary system occurs. The PBT matrix offers a similar potential to PA6 in synergistic influencing of both well‐dispersed phases. This work supports the universality of rigid polymer‐elastomer combination for the enhancement of the properties of pseudoductile polymers. Copyright © 2004 Society of Chemical Industry     

Liquid‐crystal chiral‐nematic systems with photoinduced helix inversion

Abstract— The induced helical pitch in liquid‐crystalline systems based on 4‐pentyl‐4′‐cyanobiphenyl (5CB) and containing chiral 6‐arylidene derivatives of 3(R)‐methylcyclohexanone has been found to change its sign and to decrease in the absolute value when exposed to the UV irradiation. After the photostationary state is reached, the pitch remains invariable regardless of any consequent light radiation. This state is characterized by a large helical twist which exceeds an initial one in more than three times, thereby making it possible to obtain compositions with the selective reflection of light in the visible spectral region. This phenomenon could be utilized in colour filters for display devices. The effect observed is caused by the effective reversible photochemical E‐Z‐isomerization of the chiral dopant. This was proved by photochemical preparative synthesis of one of the respective Z‐isomers and independent studies of its behaviour in 5CB.