Coating of γ-Al2O3 on the stainless steel substrate by electrophoretic deposition method

γ-Al₂O₃ coatings were prepared on aluminum-free stainless steel (SUS304) by electrophoretic deposition method. Both X-ray diffraction and scanning electron microscopy were used to study the crystalline structure and morphological features of the coatings. Themo gravimetry-differential termal analysis (TG-DTA) is used to study the thermo-chimerical reaction behavior of coatings. Catalytic activity of coatings is determined by degrading of NO_x. The results indicated that the thickness of the coatings onto SUS304 could reach 5 μm without any exfoliation at optimized conditions. Catalytic properties of samples coated by electrophoretic deposition method were highly enhanced as compared with that of samples prepared by the dip coating method.     

Prey-tracking behavior in the invasive terrestrial planarian Platydemus manokwari (Platyhelminthes, Tricladida)

Platydemus manokwari is a broadly distributed invasive terrestrial flatworm that preys heavily on land snails and has been credited with the demise of numerous threatened island faunas. We examined whether P. manokwari tracks the mucus trails of land snail prey, investigated its ability to determine trail direction, and evaluated prey preference among various land snail species. A plastic treatment plate with the mucus trail of a single species and a control plate without the trail were placed side by side at the exit of cages housing P. manokwari. All trials were then videotaped overnight. The flatworms moved along plates with mucus trails, but did not respond to plates without trails, blank control (distilled water), or with conspecific flatworm trails. When presented at the midpoint of a snail mucus trail, the flatworms followed the trail in a random direction. The flatworms showed a preference when choosing between two plates, each with a mucus trail of different land snail species. Our results suggest that P. manokwari follows snail mucus trails based on chemical cues to increase the chance of encountering prey; however, trail-tracking behavior showed no directionality.     

Identification of cuticular lipids eliciting interspecific courtship in the German cockroach, Blattella germanica

The cuticular surface of sexually mature females of the German cockroach contains a sex pheromone that, upon contact with the male's antennae, elicits a characteristic species-specific courtship behavior. This female-specific pheromone is a blend of several long-chain methyl ketones, alcohols and aldehydes, all derived from prominent cuticular hydrocarbons found in all life stages of this cockroach. We found that contact with the antennae of 5 out of 20 assayed cockroach species elicited courtship behavior in German cockroach males. The heterospecific courtship-eliciting compounds were isolated by behaviorally guided fractionation of the active crude extracts and compared to the native sex pheromone components. We identified two active compounds from the cuticular extract of the Oriental cockroach, Blatta orientalis -- 11-methylheptacosan-2-one and 27-oxo-11-methylheptacosan-2-one; the former compound was confirmed by synthesis and proved to independently stimulate courtship in German cockroach males. These compounds share common features with, but are distinct from, any of the known contact sex pheromone components. This suggests that sex pheromone reception in the male German cockroach is unusually promiscuous, accepting a wide range of compounds that share certain features with its native pheromone, thus resulting in a broad spectrum of behavioral response to other species. We propose that several characteristics of their mating system -- chiefly, absence of closely related species in the anthropogenic environment, resulting in relaxation of selection on sexual communication, and a highly male-biased operational sex ratio -- have driven males to respond with extremely low thresholds to a wide spectrum of related compounds.     

Small queens and big-headed workers in a monomorphic ponerine ant

Evolution of caste is a central issue in the biology of social insects. Comparative studies on their morphology so far suggest the following three patterns: (1) a positive correlation between queen–worker size dimorphism and the divergence in reproductive ability between castes, (2) a negative correlation among workers between morphological diversity and reproductive ability, and (3) a positive correlation between queen–worker body shape difference and the diversity in worker morphology. We conducted morphological comparisons between castes in Pachycondyla luteipes, workers of which are monomorphic and lack their reproductive ability. Although the size distribution broadly overlapped, mean head width, head length, and scape length were significantly different between queens and workers. Conversely, in eye length, petiole width, and Weber’s length, the size differences were reversed. The allometries (head length/head width, scape length/head width, and Weber’s length/head width) were also significantly different between queens and workers. Morphological examinations showed that the body shape was different between queens and workers, and the head part of workers was disproportionately larger than that of queens. This pattern of queen–worker dimorphism is novel in ants with monomorphic workers and a clear exception to the last pattern. This study suggests that it is possible that the loss of individual-level selection, the lack of reproductive ability, influences morphological modification in ants.     

Reduction behaviors of permanganate by microbial cells and concomitant accumulation of divalent cations of Mg2+, Zn2+, and Co2+

Permanganate treatment is widely used for disinfection of bacteria in surface-contaminated water. In this paper, the fate of the dissolved permanganate in aqueous solution after contact with cells of Pseudomonas fluorescens was studied. Concomitant accumulation of divalent cations of Mg~(2+), Zn~(2+), and Co~(2+) during precipitation of Mn oxides was also studied. The time course of the Mn concentration in solution showed an abrupt decrease after contact of Mn(VII) with microbial cells, followed by an increase after ～ 24 hr.XRD analysis of the precipitated Mn oxides, called biomass Mn oxides, showed the formation of low-crystalline birnessite. Visible spectroscopy and X-ray absorption near edge structure(XANES) analyses indicated that dissolved Mn(VII) was reduced to form biomass Mn oxides involving Mn(IV) and Mn(III), followed by reduction to soluble Mn(II).The numbers of electron transferred from microbial cells to permanganate and to biomass Mn oxides for 24 hr after the contact indicated that the numbers of electron transfer from microbial cell was approximately 50 times higher to dissolved permanganate than to the biomass Mn oxides in present experimental conditions. The 24 hr accumulation of divalent cations during formation of biomass Mn oxides was in the order of Co~(2+) Zn~(2+) Mg~(2+).XANES analysis of Co showed that oxidation of Co~(2+) to Co~(3+) resulted in higher accumulation of Co than Zn and Mg. Thus, treatment of surface water by KMnO_4 solution is effective not only for disinfection of microorganisms, but also for the elimination of metal cations from surface water.     

Alkaline hydrolysis of photovoltaic backsheet containing PET and PVDF for the recycling of PVDF

Recovering fluorine from end-of-life products is crucial for the sustainable production and consumption of fluorine-containing compounds because fluorspar, an important natural resource for fluorine, is currently at a supply risk. In this study, we investigated the feasibility of chemically recycling a fluorine-containing photovoltaic (PV) backsheet for fluoropolymer recycling. Herein, a PV backsheet consisting of laminated polyethylene terephthalate (PET) and polyvinylidene fluoride (PVDF) was treated with different concentrations of sodium hydroxide (NaOH) to hydrolyze the PET layer to water-soluble sodium terephthalate (Na₂TP) and to separate pure PVDF layer as a solid material. Optimized alkaline conditions (up to 10 M NaOH at 100 °C for 2 h) were determined, under which 87% of the PET layer could be decomposed without any significant deterioration of the PVDF layer. The hydrolysis kinetics of PET layer in NaOH could be explained by the modified shrinking-core model. Considering that the mass of end-of-life PV panels in Japan is estimated to increase to approximately 280,000 tons per year by 2036, PV backsheets are attractive candidates for fluoropolymer recycling, which can be effectively achieved using chemical recycling approach demonstrated in this study.

     

Bench-scale PVC swelling and rod milling of waste wire harnesses for recovery of Cu,PVC, and plasticizers

Journal of Material Cycles and Waste Management - In this study, we conducted bench-scale investigations for the recovery of Cu wires, PVC coatings, and plasticizers from long non-uniform cables by...     

Characterization and mapping of enset-based home-garden agroforestry for sustainable landscape management of the Gurage socioecological landscape in Ethiopia

Environmental Science and Pollution Research - Developing strategies that counter the ongoing homogenization trends of home-garden agroforestry systems is required to maintain diversity and...     

Effects of heating rate and temperature on product distribution of poly-lactic acid and poly-3-hydroxybutyrate-co-3-hydroxyhexanoate

In this study, poly-lactic acid (PLA) and poly-3-hydroxybutyrate-co-3-hydroxyhexanoate (PHBH) were pyrolyzed at various temperatures (300, 350, 400, 500, 600, and 700 °C) and heating rates (5, 10, 20, 30, and 40 °C min⁻¹) using a pyrolysis–gas chromatograph/mass spectrometer (Py–GC/MS). The results revealed that the main pyrolysis products of PLA were acetaldehyde, lactide (including meso-lactide and d-, l-lactide), and oligomers. Crotonic acid and its oligomers accounted for most of the PHBH pyrolyzates. The pyrolysis temperature significantly correlated with the product distribution, but the heating rate had a small effect on the product distribution. Lactide and crotonic acid were two kinds of high-value chemicals, and their highest yields were obtained at 400 and 600 °C with 29.7 and 72.6 area %, respectively. Secondary reactions could not be neglected at 700 °C, and acetaldehyde and crotonic acid decreased to 65.0 and 69.6 area %, respectively. These results imply that pyrolyzate selectivity can be controlled by temperature management during pyrolysis.