Synthesis and Modification of Amine-Terminated Maleic Anhydride-Ethylene Copolymers by Benzaldehyde Derivatives: Characterization and Antimicrobial Properties

Antimicrobial polymers based on poly(ethylene-alt-maleic anhydride) (PEMA) were prepared. Amination of poly(ethylene-alt-maleic anhydride) using diamines of different chain lengths such as ethylenediamine (EDA) and hexamethylenediamine (HMDA) afforded terminal amino groups on the polymers. Antimicrobial polymers were obtained by immobilization of benzaldehyde and its derivatives, which include 4-hydroxybenzaldehyde and 2,4-dihydroxybenzaldehyde onto amine-terminated polymers. The antimicrobial activity of the prepared polymers were examined against different types of microorganisms including Gram-positive and Gram-negative bacteria as well as some fungi. The obtained results revealed that the antimicrobial activity increased with increasing the number of phenolic hydroxyl group and with increasing the spacer length.     

Photocurable shape-memory polyether-polythioether/graphene nanocomposites and the study of their thermal conductivity

Herein a method is described to prepare photocurable thermally-conductive shape memory epoxy/ graphene composites. By photopolymerizing the epoxy resin diglycidyl ether of bisphenol A with an allyl-functionalized ditertiary amine as the curing agent, jointly with a multifunctional thiol, a crosslinked polyether-polythioether co-network was obtained. The presence of a soft domain like the flexible polythioethers enable the co-network to display shape memory properties. By varying the polyether to polythioether ratio it was possible to modulate the shape memory characteristics of the composite. The effect of the concentration of graphene nanoplatelets (GNP) in the composite was also investigated. Shape memory performances revealed excellent values of shape recovery and shape fixity with maximums of 98 and 99% respectively. The temporary- shaped composites with higher concentration of polythioethers and GNP regained their permanent shapes in 2–3 s when heated above the programming temperature. The thermal conductivity in the composites reached 0.39 W/m°K for the composite with 15% w/w of GNP. The presence of the polythioethers in the co-network enhanced the toughness of the composite as revealed by the impact resistance analysis.     

Synthesis and characterization of polyphenylene vinylenes having <Emphasis Type="Italic">m</Emphasis>-terphenyl group: comparison of their optical properties

A series of alternate block copolymers of polyphenylene vinylenes that have 1,3-dioctyloxy phenylene in the center of kinked m-terphenyl group as one of the building blocks with either one of the aromatic groups, viz., 1,4-dioctyloxy benzene, 4,6-dioctyloxy benzene and 4,4′-dioctyloxy biphenyl, was synthesized through Heck polymerization. These alternate block copolymers, viz., poly(2,5-bis(octyloxy)phenylene vinylene alt 4′,6′-bis(octyloxy)-1,1′:3′,1″-terphenylene) (P1), poly(2,4-bis(octyloxy)phenylene vinylene alt 4′,6′-bis(octyloxy)-1,1′:3′,1″-terphenylene) (P2) and poly(4,4′-bis(octyloxy-3,3′-biphenylene vinylene alt 4′,6′-bis(octyloxy)-1,1′:3′,1″-terphenylene) (P3), were characterized for their thermal and optical properties. The synthesized polymers had good solubility in organic solvents and were stable up to 350 °C. The molecular weights of the synthesized polymers were in the range 4370–10,900 Da with polydispersity range 1.52–1.65, which were measured by the gel permeation chromatography technique. The optical properties of these polymers showed absorptions in solution at around 400, 329, and 345 nm for P1, P2, and P3 polymers, respectively. The photoluminescence emission maxima of the polymers were at around 461 nm with a shoulder 439 and 424 nm for P1, P2, and P3, respectively. Photoluminescence emission of films of these polymers showed minimum redshift (20 nm) when compared with spectra of their solutions. The optical and photoluminescence emission properties of these polymers were found to vary on the backbone structure.     

A new method in designing compatibility and adhesion of EVA/PMMA blend by using EVA-<Emphasis Type="Italic">g</Emphasis>-PMMA with controlled graft chain length

Atom transfer free radical polymerization (ATRP) was employed in a synthesis of graft polymer EVA-g-PMMA with controlled length of side PMMA chains. Three steps of synthesis: partial hydrolysis of EVA, esterification with chloroacetyl chloride and ATRP grafting were performed to produce EVAOH, macroinitiator EVACl and grafted polymers G8020 (EVA/PMMA?=?80/20 wt%) and G6040 (EVA/PMMA?=?60/40 wt%). FTIR, Raman and NMR spectroscopy were used in the determination of the chemical structure and modification of EVA. Transmitted light and dark field microscopy showed higher affinity for coil formation of EVA-g-PMMA with longer PMMA side chains, i.e. G6040 compatibilizer. Morphological, thermal and adhesive properties of optical fiber adhesives of graft polymers and polymer blends poly(ethylene-co-vinyl acetate)-blend-poly(methyl methacrylate) (EVA/PMMA) compatibilized with 1 wt% of EVA-g-PMMA, were studied. Image analysis of SEM micrographs showed effective compatibilization with short grafted chains (G8020) that was indicated by lower porosity characteristics. TG/DTG analysis enabled determination of degree of hydrolysis and amount of chloro-functionalized groups. DSC analysis showed higher thermal stability of G8020 polymer. Single lap joint of adhesives/optical fibers were subjected to adhesive testing and obtained results for maximal force applied and adhesive failure suggested the visible influence of the length of graft chains on adhesion.     

Reinforcement effect of poly (methyl methacrylate)-<Emphasis Type="Italic">g</Emphasis>-cellulose nanofibers on LDPE/thermoplastic starch composites: preparation and characterization

The effect of cellulose nanofibers (CNFs) and poly [methyl methacrylate (MMA)]-grafted cellulose nanofibers (CNF-g-PMMA) on mechanical properties and degradability of a 75/25 low density polyethylene/thermoplastic starch (LDPE/TPS) blend was investigated. Graft copolymerization on CNFs was performed in an aqueous suspension by free radical polymerization using MMA as an acrylic monomer. In addition, a LDPE/TPS blend was reinforced by different amounts of CNFs (1–5 wt%) and CNF-g-PMMA (1–7 wt%) using a twin-screw extruder. A 61% grafting of PMMA on the surface of CNFs was demonstrated by gravimetric analysis. Moreover, after modification the X-ray photoelectron spectroscopy analysis showed a 20% increase of carbon atoms on the surface of CNFs and a 22.6% decrease in the oxygen content of its surface. The mechanical properties of the CNFs-modified composites were significantly improved compared to the unmodified nanocomposites. The highest tensile strength and Young’s modulus were obtained for the composites reinforced by 3 and 7 wt% CNF-g-PMMA, respectively. The degradability of cellulose nanocomposites was studied by water absorption and soil burial tests. Surface modification of CNFs lowered water absorption, and soil burial test of the LDPE/TPS blend showed improvement in biodegradability by addition of CNF-g-PMMA.     

Effect of Biopolymer Blend Matrix on Structural,Optical and Biological Properties of Chitosan–Agar Blend ZnO Nanocomposites

The present research is focused on the development of ecofriendly biopolymer blend based nanocomposites to enhance the effect of cytotoxic activity. Novel eco-friendly synthesis of pure Chitosan–Agar blend and Chitosan–Agar/ZnO nanocomposites was successfully synthesized by in-situ chemical synthesis method. The influence of Chitosan–Agar (1:1 wt/wt%) concentrations (0.1, 0.5, 1 and 3 g) was studied. The presence of ZnO nanoparticles in Chitosan–Agar polymer matrix was confirmed by UV, FTIR, XRD, FESEM, EDAX and TEM. The crystallite size of the nanocomposites in the range of 12–17 nm is observed from XRD analysis. PL and UV reveal that Nanocomposites shows an blue shift by increase in the blend concentrations. TEM analysis shows that 0.1 and 3 g of Chitosan–Agar/ZnO Nanocomposites are in spindle and spherical shape with polycrystalline nature. The prepared Nanocomposites shows the respectable Antibacterial activity against Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Pseudomonas aureginosa and Klebsilla pneumonia) bacteria. The potential toxicity of Chitosan–Agar/ZnO nanocomposites was studied for normal (L929) and breast cancer cell line (MB231). The result of this investigation shows that the Chitosan–Agar/ZnO nanocomposites deliver a dose dependent toxicity in normal and cancer cell line.     

Annealing effect on the shape memory properties of polylactic acid (PLA)/thermoplastic polyurethane (TPU) bio-based blends

PLA and TPU were melt-blended to form shape memory bio-based blends with or without post-annealing effect. To the authors’ best knowledge, this is the first work to discuss the annealing effect on the PLA-based SMP blends. Annealed TPU showed regularly fractured surfaces unlike the macro-phase segregated domains for non-annealed TPU. After 3 h-annealing treatment, spherulites were observed for PLA, but not for TPU. The crystallinity of PLA increased, close to 3-fold increment, for annealed blends in comparison with non-annealed blends. The shape memory behaviors of PLA/TPU blends predeformed under three different predeformation temperatures (25, 80, 120 °C) were investigated. The annealing effect was helpful in enhancing the shape fixing ratio of the PLA/TPU (60/40) blend at high predeformation temperature of 120 °C in comparison with 25 °C. However, the suitable selection of the optimum predeformation temperature at 80 °C outweighed the annealing effect to attain the high shape fixing ratio, even in the case of non-annealed blends. The annealing effect often increased the perfection of crystal domains/interfaces and the larger crystal sizes, which would be detrimental to the molecular extensibility. The overall annealing effect on the shape recovery ratios were quite effective for both PLA/TPU blends of 80/20 and 60/40 without sacrificing the shape fixing ratios at the optimum predeformation temperature of 80 °C, attributing to the increased crystallinity of PLA and homogenized phase domains of TPU. Particularly, the annealing treatment did significantly increase the recovery ratio of the blends, more than 2-fold increment, especially for PLA/TPU (60/40) blend. At both lower or higher predeformation temperatures, the stress concentration between the increased crystalline domains and amorphous regions tended to dominate the annealing effect, leading to a negative contribution to the shape recovery processes.     

Electrospinning of chitosan/PVA nanofibrous membrane at ultralow solvent concentration

In this work, chitin flakes were deacetylated with 50% (w/v) sodium hydroxide under nitrogen atmosphere at 120 °C for 80 min to obtain chitosan. The chitosan produced was characterized for degree of deacetylation (DD) and molecular weight. Chitosan with the DD of 78–80% was reproducibly obtained. Molecular weight showed an inverse relationship with concentration of NaOH. Chitosan nanofibrous membrane was prepared via the electrospinning of chitosan/polyvinyl alcohol (CH/PVA) aqueous solutions with varying blend compositions. The characteristics of CH/PVA nanofibrous membranes were studied as a function of viscosity of solution and applied voltage. A uniform nanofibrous membrane of average fibre diameter of 80–300 nm was obtained with blend of 2% (w/v) chitosan solution in 1% (v/v) acetic acid and 5% (w/v) PVA in distilled water in the electric field of 20–25 kV with varying proportion of CH/PVA. With the CH/PVA mass ratios; 40/60 to 10/90, electrospinning of nanofibres could be done. The electrospun nanofibrous membrane was analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Thermo gravimetric analysis (TGA). SEM images showed that the morphology and diameter of the nanofibres were mainly affected by the weight ratio of CH/PVA. XRD and FTIR confirmed the strong intermolecular hydrogen bonding between the molecules of Chitosan and PVA.     

Carbon nanotubes and graphene into thermosetting composites: Synergy and combined effect

This work analyzes the morphology and behavior of hybrid composites reinforced with carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs). In order to avoid the weak interface of laminar nanofillers, GNPs were functionalized with amine groups. Different tendencies were observed as a function of the measured property. Storage modulus showed a synergic trend, being the stiffness of hybrid CNT/GNP/epoxy composites higher than the corresponding ones measured in neat epoxy composites reinforced with CNTs or GNPs. In contrast, the thermal and electrical conductivity increased with the nanofiller addition, the final value of the mentioned properties in the hybrid composites was strongly influenced by specific graphitic nanofiller. Neat GNP/epoxy composites showed the highest thermal conductivity, while neat CNT/epoxy composites presented the highest electrical conductivity. This behavior is explained by the observed morphology. All composites exhibited a suitable nanofiller dispersion. However, on hybrid GNP/CNT/epoxy composites, CNTs tend to be placed between nanoplatelets, forming bridges between nanoplatelets. This morphology implies a less effective electrical network, limiting the synergic effect in the properties, which requires percolation. In spite of this, the hybrid GNP/CNT/epoxy composites showed a better combination of properties than the neat composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46475.     

Identification and Optimization of Microbial Attractants for <Emphasis Type="Italic">Philornis downsi</Emphasis>, an Invasive Fly Parasitic on Galapagos Birds

We investigated the role of olfactory cues from actively fermenting yeast (Saccharomyces cerevisiae) in attraction of adult Philornis downsi and identified two synergistically attractive yeast volatiles. Larvae of this invasive fly parasitize the hatchlings of passerines and threaten the Galapagos avifauna. Gas chromatography coupled with electroantennographic detection (GC-EAD), coupled gas chromatography-mass spectrometry (GC-MS), and field trapping experiments were used to identify volatile compounds from a yeast-sugar solution. EAD responses were consistently elicited by 14 yeast volatiles. In a series of field trapping experiments, a mixture of the 14 EAD-active compounds was similarly attractive to P. downsi when compared to the yeast-sugar solution, and we found that acetic acid and ethanol were essential for attraction. A mixture of 0.03 % acetic acid and 3 % ethanol was as attractive as the 14-component blend, but was not as attractive as the yeast-sugar solution. Philornis downsi showed positive and negative dose-responses to acetic acid in the ranges of 0.01 ~ 0.3 % and 0.3 ~ 9 %, respectively. Further optimization showed that the mixture of 1 % acetic acid and 3 % ethanol was as attractive as the yeast-sugar solution. Both mixtures of acetic acid and ethanol were more selective than the yeast-sugar solution in terms of non-target moths and Polistes versicolor wasps captured. These results indicate that acetic acid and ethanol produced by yeasts are crucial for P. downsi attraction to fermented materials on which they feed as adults and can be used to manage this invasive fly in Galapagos.     

Effect of poly(styrene-co-maleic anhydride) on physical properties and crystalline behavior of nylon-6/PEBA blends

This study investigated the effect of blending poly(styrene-co-maleic anhydride) (SMA) on the mechanical and thermal properties of nylon-6/polyether block amide (PEBA) blend. In these blends, nylon-6 was toughened with PEBA using SMA as the compatibilizer. All the blends were prepared via direct melt compounding using a co-rotating twin screw extruder. The amount of PEBA added affected the crystallization characteristics and the relative ratio of γ and α crystalline phases of Nylon 6. The crystallization rate of Nylon 6 was also affected by the cooling rate and the amount of PEBA added. The results of mechanical tests showed that the tensile properties, flexural properties, and impact strengths of the nylon-6/PEBA were all increased when blended with 1 wt% of SMA, at both 23 and ?20 °C. However, for neat nylon-6, the impact strength was not affected despite that both tensile and flexural properties were increased by the blending of SMA. The results indicated that SMA can increase the compatibility between nylon-6 and PEBA, thus expanding the usage of nylon-6/PEBA blend in low-temperature applications.     

Volatiles of <Emphasis Type="Italic">Solena amplexicaulis</Emphasis> (Lam.) Gandhi Leaves Influencing Attraction of Two Generalist Insect Herbivores

Epilachna vigintioctopunctata Fabr. (Coleoptera: Coccinellidae) and Aulacophora foveicollis Lucas (Coleoptera: Chrysomelidae) are important pests of Solena amplexicaulis (Lam.) Gandhi (Cucurbitaceae), commonly known as creeping cucumber. The profiles of volatile organic compounds from undamaged plants, plants after 48 hr continuous feeding of adult females of either E. vigintioctopunctata or A. foveicollis, by adults of both species, and after mechanical damaging were identified and quantified by GC-MS and GC-FID analyses. Thirty two compounds were detected in volatiles of all treatments. In all plants, methyl jasmonate was the major compound. In Y-shaped glass tube olfactometer bioassays under laboratory conditions, both insect species showed a significant preference for complete volatile blends from insect damaged plants, compared to those of undamaged plants. Neither E. vigintioctopunctata nor A. foveicollis showed any preference for volatiles released by heterospecifically damaged plants vs. conspecifically damaged plants or plants attacked by both species. Epilachna vigintioctopunctata and A. foveicollis showed attraction to three different synthetic compounds, linalool oxide, nonanal, and E-2-nonenal in proportions present in volatiles of insect damaged plants. Both species were attracted by a synthetic blend of 1.64 μg linalool oxide?+?3.86 μg nonanal?+?2.23 μg E-2-nonenal, dissolved in 20 μl methylene chloride. This combination might be used as trapping tools in pest management strategies.     

Core/shell morphologies in recycled poly(ethylene terephthalate)/linear low-density polyethylene/poly(styrene-<Emphasis Type="Italic">b</Emphasis>-(ethylene-<Emphasis Type="Italic">co</Emphasis>-butylene)-<Emphasis Type="Italic">b</Emphasis>-styrene) ternary blends

Compatibilizer plays very important roles in preparing high performance polymer composites, not only for the ternary immiscible polymer blends, but also for the recycled and reused of waste plastics mixture. Generally, the compatibilizers can be used as the toughening agent in blending polymer materials. In the present work, the poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) or maleic anhydride-grafted poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS-g-MA) acts as the compatibilizer and toughening agent for the preparation of R-PET/LDPE/SEBS (70/20/10) ternary blends. It must be pointed that the ternary blends are costlessly and conveniently prepared from the recycled poly(ethylene terephthalate) (R-PET) and linear low density polyethylene (LLDPE) through a melt blending in a co-rotating twin-screw extruder and injection moulded. The morphologies of the ternary blends are characterized by scanning electron microscopy (SEM). It was found that the blends contains reactive or non-reactive compatibilizer, the morphology originates from the LLDPE particles encapsulated by both SEBS and SEBS-g-MA. So, it results to the reduced interfacial tension between of the R-PET and SEBS-g-MA, in which the grafted chains of PET-g-SEBS-g-MA formed through in situ reaction between R-PET and SEBS-g-MA phases. Therefore, core–shell particles with smaller diameter disperse uniformly in the blends. Moreover, the good compatibilization and corresponding morphologies induce in balanced mechanical and thermal properties. DSC analysis show the dispersed phase particles could act as nucleating agent in the R-PET matrix, which results the improvement of the crystallization temperature. And it was also observed the decreased nucleation activity in graft copolymers in the R-PET/LLDPE/SEBS-g-MA blends. Notched Charpy impact strength and elongation at break are improved by the addition of compatibilizer.     

TPU/PCL/nanomagnetite ternary shape memory composites: studies on their thermal, dynamic-mechanical, rheological and electrical properties

Shape memory polymer composites based on a blend of thermoplastic polyurethane (TPU) segmented block copolymer and poly(ε-caprolactone) (PCL) with weight ratio of 70/30 and various nanomagnetite contents (0–5 wt%) were prepared by melt blending of TPU and PCL, together with a masterbatch of TPU/nanomagnetite. The samples were compounded for 10 min at 200 °C using an internal mixer. Synthesized nanomagnetite powder was introduced to the masterbatch via a solution mixing method using a high-intensity ultrasonic horn. Subsequently, thermal, mechanical, rheological and electrical properties of the TPU/PCL/nanomagnetite shape memory composites were investigated through various tests. The degree of crystallization of the PCL component in the composite structure was inspected by differential scanning calorimetry (DSC) and X-ray diffraction measurements. The results revealed that the percentage of crystallinity and the melting temperature of the PCL component changed in the presence of magnetite nanoparticles, which was related to the nanoparticles acting as nucleants. Observing a single glass transition temperature (T _g) in DSC thermograms of the samples was indicative of good compatibility of the TPU and PCL components in the composite structure. This was also confirmed by dynamic-mechanical analysis in which the loss modulus curves showed a single glass transition temperature. Moreover, the loss modulus peak at glass transition was lowered and broadened by addition of nanomagnetite, by which it was assumed that introducing nanoparticles into the system changed the mechanism of glass transition due to particle–matrix interactions. The dynamic rheological and electrical resistivity experiments verified the existence of a low percolation threshold at about 2 wt% nanomagnetite. The state of nanomagnetite dispersion in the masterbatch and the microstructure of the ternary composites were characterized by scanning electron microscopy. Finally, adding nanomagnetite led to weakening of shape recovery of the polymer blend, with shape recovery dropping to 70 % at 5 % of nanomagnetite.     

Enhanced toughness for polyamide 6 with a core-shell structured polyacrylic modifier

Polyamide 6 (PA 6) is an important thermoplastic with excellent strength, stiffness, and good chemical resistance. The notch sensitivity and low notch impact toughness of PA 6, however, limit its application. A core-shell structured polyacrylic modifier, poly(n-butyl acrylate)/poly(methyl methacrylate-co-methacrylic acid) modifier (PBM-co-MAA), was used to toughen PA 6. To study the effect of PBM-co-MAA particles on the toughness of PA 6, various contents of poly(BA) in PBM-co-MAA latexes of 300 nm were synthesized by seed emulsion polymerization. The results showed that polymerization had an instantaneous conversion higher than 95 wt% and an overall conversion higher than 97 wt%. The PBM-co-MAA particles had a clear core–shell structure confirmed by transmission electron microscope (TEM). The mechanical properties of PA 6/PBM-co-MAA blends showed that the notch impact strength of PA 6/PBM-co-MAA blends with 85 wt% poly(BA) and 0.5 wt% MAA in PBM-co-MAA was nearly six times greater than that of pure PA 6, being consistent with the scanning electron microscope (SEM) observations on the fractured surfaces. The notch impact strengths of PA 6/PBM-co-MAA blends were also better than that of PA 6/PBM blend, which did not contain MAA functional group in the modifier. Dynamic mechanical analysis (DMA) results showed improved compatibility between PA 6 matrix and core-shell toughening modifier, which should contain a functional group in the shell layer and a suitable core rubbery content to toughen PA 6 effectively.     

Novel amphiphilic temperature responsive graft copolymers PCL-<Emphasis Type="Italic">g</Emphasis>-P(MEO<Subscript>2</Subscript>MA-<Emphasis Type="Italic">co</Emphasis>-OEGMA) via a combination of ROP and ATRP: synthesis,characterization, and sol-gel transition

A series of well-defined novel amphiphilic temperature-responsive graft copolymers containing PCL analogues P(αClεCL-co-εCL) as the hydrophobic backbone, and the hydrophilic side-chain PEG analogues P(MEO₂MA-co-OEGMA), designated as P(αClεCL-co-εCL)-g-P(MEO₂MA-co-OEGMA) have been prepared via a combination of ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). The composition and structure of these copolymers were characterized by ¹H NMR and GPC analyses. The self-assembly behaviors of these amphiphilic graft copolymers were investigated by UV transmittance, a fluorescence probe method, dynamic light scattering (DLS) and transmission electron microscopy (TEM) analyses. The results showed that the graft copolymers exhibited the good solubility in water, and was given the low critical temperature (LCST) at 35(±1) °C, which closed to human physiological temperature. The critical micelle concentrations (CMC) of P(αClεCL-co-εCL)-g-P(MEO₂MA-co-OEGMA) in aqueous solution were investigated to be 2.0 × 10^?3, 9.1 × 10^?4 and 1.5 × 10^?3 mg·mL^?1, respectively. The copolymer could self-assemble into sphere-like aggregates in aqueous solution with diverse sizes when changing the environmental temperature. The vial inversion test demonstrated that the graft copolymers could trigger the sol-gel transition which also depended on the temperature.     

Fatal Attraction: <Emphasis Type="Italic">Ricinus communis</Emphasis> Provides an Attractive but Risky Mating Site for <Emphasis Type="Italic">Holotrichia parallela</Emphasis> Beetles

The castor bean, Ricinus communis L., is a non-host plant for the large black chafer, Holotrichia parallela Motschulsky (Coleoptera: Scarabaeidae). In laboratory bioassays we found that this plant was no less attractive than the main host plant (peanut, Arachis hypogaea) and three food plant species: velvetleaf (Abutilon theophrasti), the glossy privet (Ligustrum lucidum), and the Siberian elm (Ulmus pumila). In field trapping experiments a Soxhlet extract of castor bean leaves caught more beetles than the optimal sex lure blend [(R)-(?)-linalool and (L)-isoleucine methyl ester blended in a ratio of 1:4], compared at equal doses (500 μl), and laboratory bioassays indicated that a castor bean plant could enhance the attractiveness of different blend ratios of sex lures. Olfactometer bioassays showed that males prefer volatiles emitted from different combinations of castor bean plant extracts and a signaling female over a female alone. In the presence of castor bean plants copulation rates of H. parallela were highest among all test environments both in laboratory bioassays (60%) and in field tests (70%). This study, combined with our previous observation of the feeding behavior of H. parallela adults on castor bean leaves, suggests that castor bean plants may provide an attractive but risky mating site for H. parallela beetles. The enhancement of male mate-location and copulation rate in the presence of castor bean plants can balance its paralytic effects on H. parallela after intake of potential toxins contained in its leaves.     

Synthesis and characterization of exfoliated polystyrene grafted hexagonal boron nitride nanosheets and their potential application in heat transfer nanofluids

Three different methods were used to develop surface-modified hexagonal boron nitride (h-BN) nanosheets, and polystyrene grafting was performed by an indirect covalent bond formation between modified h-BN nanosheets and styrene molecules through surface initiated atom transfer radical polymerization (SI-ATRP) approach. In all methods, an alkyl bromide as the ATRP-initiating site was first introduced on h-BN nanosheets and an SI-ATRP reaction of styrene from the initiator immobilized h-BN surface was achieved. The structure of synthesized PS grafted h-BN nanosheets (PS-g-h-BN) was identified and characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, field emission scanning electron microscopy, transmission electron microscopy, and atomic force microscopy methods. The functionalization promoted the exfoliation of h-BN layered structure into few layer sheets where the thickness of the sheets was dependent on the modification technique and the content of polymer grafted on nanosheets. The highest grafting content of PS-g-h-BN nanosheets was obtained around 20% which could enhance thermal conductivity of mineral oil-based nanofluids with the minimum concentration of the nanofiller (0.01 wt%). The electrical and physical properties of the nanofluid were also investigated. According to the results, the dielectric loss reduced by increase in nanofiller concentration was an indication of the enhanced dielectric nature of nanofluid. In addition, exfoliated PS-g-h-BN nanosheets dispersions were shown to be stable in mineral oil up to 2 months and this stability was linked to the presence of polymer chains followed by the formation of van der Walls interactions between the grafted polymer and the fluid.     

Inhibitory Effects of Semiochemicals on the Attraction of an Ambrosia Beetle <Emphasis Type="Italic">Euwallacea</Emphasis> nr. <Emphasis Type="Italic">fornicatus</Emphasis> to Quercivorol

The Euwallacea fornicatus (Eichhoff) species complex includes the polyphagous shot hole borer (PSHB), an ambrosia beetle infesting avocado limbs, Persea americana Mill. Synthetic quercivorol, a monoterpene alcohol, is known to attract females (males are flightless) over a range of release rates spanning three orders of magnitude. The upper release dose was extended 10-fold using sticky traps baited with quercivorol released at 1× (0.126 mg/day), 10×, and 108× relative rates to obtain a dose?response curve fitting a kinetic formation function. Naturally infested limbs of living avocado trees were wrapped with netting to exclude the possibility of catching emerging beetles on the encircling sticky traps. The results indicate PSHB are significantly attracted to infested limbs. Ethanol released over a 64-fold range (lowest rate of 7.5 mg/day) was moderately inhibitory of PSHB attraction to 1× quercivorol. β-caryophyllene and eucalyptol did not appear to affect attraction at the rates tested. A field test of potential inhibitors of 1× quercivorol was done using ~1 mg/day releases of monoterpene ketones: (?)-(S)-verbenone, (+)-(R)-verbenone, 3-methyl-2-cyclo-hexen-1-one (MCH or seudenone), piperitone, (+)-(S)-carvone, and racemic cryptone. Only piperitone and the two enantiomers of verbenone were strongly inhibitory. A blend of piperitone and verbenone tested together at different distances (0, 0.5, 1, 2, and 4 m) from a 1× quercivorol baited sticky trap became increasingly ineffective in inhibiting the attractant as separation distance increased. Due to the relatively short-range repellency (<1 m), the inhibitors would need to be released from several places on each tree to effectively repel PSHB from avocado trees. Effective attraction radii, EAR, and circular EARc are estimated for the quercivorol baits released at 1×, 10× and 108× rates. Push-pull simulations of moving beetles were performed in 1 ha plots with 2, 4, or 16 traps of 10× EARc and 400 trees (0, 1, or 3 inhibitors per tree) of which ten had an infested limb (EARc?=?0.5 m). The simulations indicate that push-pull methods would be more effective in reducing PSHB mating than simply using mass-trapping alone.     

A process for simultaneously achieving phenol biodegradation and polyhydroxybutyrate accumulation using <Emphasis Type="Italic">Cupriavidus taiwanesis</Emphasis> 187

Cupriavidus taiwanensis 187 is reportedly efficient in achieving the degradation of phenol and accumulation of polyhydroxybutyrate (PHB). This study attempted to optimize the cultivation conditions and fermentation strategies for phenol degradation and PHA accumulation by C. taiwanensis 187. After the cultivation conditions were optimized, the conditions required for achieving phenol degradation (100%) and PHB accumulation (51 mg/L) by C. taiwanensis 187 were identified as 30 °C and 200 rpm, when the cultivation time was around 7 h. The accumulation of PHB was further increased from 72 to 213 mg/L by feeding phenol in three rounds into the fermenter along with the exhaustion of dissolved oxygen, which could totally degrade the phenol at around 1500 mg/L. Production of PHB by C. taiwanensis 187 was confirmed by GC, ¹H-NMR, and ¹³C-NMR analyses. Each analytical result proved that C. taiwanensis 187 was able to use phenol as the sole carbon source for producing PHB. Finally, these results revealed that the phenol degraded by C. taiwanensis 187 mainly contributed to cell growth rather than PHB accumulation. These results indicated that the strain C. taiwanensis 187 could be used to degrade phenol to obtain usable biological polyesters.