Species of infraorder Gryllidea, or crickets, are useful invertebrate models for studying developmental biology and neuroscience. They have also attracted attention as alternative protein sources for human food and animal feed. Mitochondrial genomic information on related invertebrates, such as katydids, and locusts, has recently become available in attempt to clarify the controversial classification schemes, although robust phylogenetic relationships with emphasis on crickets remain elusive. Here, we report newly sequenced complete mitochondrial genomes of crickets to study their phylogeny, genomic rearrangements, and adaptive evolution. First, we conducted de novo assembly of mitochondrial genomes from eight cricket species and annotated protein-coding genes (PCGs) and transfer and ribosomal RNAs using automatic annotations and manual curation. Next, by combining newly described PCGs with public data of the complete Gryllidea genomes and gene annotations, we performed phylogenetic analysis and found gene order rearrangements in several branches. We further analyzed genetic signatures of selection in ant-loving crickets (Myrmecophilidae), which are small wingless crickets that inhabit ant nests. Three distinct approaches revealed two positively selected sites in the cox1 gene in these crickets. Protein 3D structural analyses suggested that these selected sites could influence the interaction of respiratory complex proteins, conferring benefits to ant-loving crickets with a unique ecological niche and morphology. These findings enhance our understanding of the genetic basis of cricket evolution without relying on estimates based on a limited number of molecular markers.
We have studied the crystallization of blended poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT). The effect of transesterification in the blend on crystallization has been examined by thermal analysis and optical microscopy. At higher temperatures above 200 C, the crystallization of one of the component (PBT) was enhanced by the existence of the crystals of another component (PET) for the intermediate degree of transesterification. The results indicate the importance of the details of the transesterification at molecular scale. and ethylene-acrylic acid copolymer 7 have been examined as blending polymers to improve the mechanical properties or gas permeability of PET. Poly(butylene terephthalate) (PBT) has also been studied as a blend polymer because of its softer mechanical property and faster crystallization than PET. 8,9 PET and PBT are miscible with each other and reactive by transesterification between the components.10-12 The process of transesterification has been examined by Fakirov et al. 10Backson et al.11 and Matsuda et al. 12 also studied the reaction by using NMR.The aim of this study is to analyze the crystallization process of the blend of PET/PBT by thermal analysis and by optical microscopy. It is known that PET and PBT crystallize separately in the miscible blend of PET/PBT. 13 It has also been reported that the crystallization of PET component is enhanced in the blend. 13,14 We examine the enhancement of crystallization behaviors of PET and PBT in the blend under the influence of different degrees of the reactive transesterification. EXPERIMENTAL Sample PreparationPET and PBT used for extruded films have intrinsic viscosities of 0.62 and 1.20 dl/g. PET was melted by a single screw extruder (60 mm screw diameter) at 285 C. PBT and two kinds of PET/PBT blended film (1/1 weight ratio) were prepared by the extruder at temperatures of 260 C (PBT), 260 and 295 C (EB260, EB295), respectively, at the residence time of 4 min. The melted polymer was molded into sheets on metal drum at 30 C. The thickness are 100-150 mm. Blended film was also made by solution casting (EBsol). Solutions of PET and PBT were prepared in phenol/tetrachloroethane of 6/4 (w/w), such that the total concentration of polymer was 5% (w/v) at room temperature. EBsol film of approximately 80 mm in thickness was obtained after the evaporation of solution at 23 C. MeasurementThermal behavior was examined by differential scanning calorimetry (TA Instrument, DSC Q100). Measurements were done by constant cooling and under isothermal conditions. The cooling rate was 5, 20 and 40 C/min after holding 1 min at 280 C. The isothermal condition was achieved by the cooling rate of 60 C/min after holding 1 min at 280 C. The crystallization process was also observed on a hot stage (LINKAM; model TH-600PH) at a cooling rate of 10 C/min by optical microscopy. Figure 1 shows the DSC thermograms at the cooling rates of 20 C/min. It is seen that the exothermic peaks of crystallization appear at higher temperatures in the order ...
We present an ab initio calculation to understand electronic structures and optical properties of a tungsten carbide WC being a major component of a TiCN-based cermet. The TiCN-based cermet is widely used as a cutting tool, and is discarded as usual after use. On the other hand, cermet itself is also a famous ingredient of a solar absorption film. We found that the WC has a fairly low-energy plasma excitation $$\sim$$ ∼ 0.6 eV (2 $$\upmu$$ μ m) and therefore can be a good constituent of a solar selective absorber. The evaluated figure of merit for photothermal conversion is prominently high compared to those of the other materials included in the TiCN-based cermet. The imaginary part of the dielectric function is considerably small around the zero point of the real part of the dielectric function, corresponding to the plasma excitation energy. Therefore, a clear plasma edge appeared, ensuring the high performance of the WC as the solar absorber. This is a fascinating aspect, because the wasted TiCN-based cermet cutting tool can be recycled as the solar absorption film after proper treatments and modifications.
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