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The intermediate stages of speciation are important for understanding the processes involved in the creation of biodiversity, and also comprise a number of interesting phenomena. However, difficulties are associated with dividing clear speciation stages because speciation is a continuous process. Therefore, the elucidation of speciation is an interesting and important task in evolutionary biology. We herein present an example of a species in an intermediate stage of speciation using the giant water bug Appasus japonicus (Heteroptera, Belostomatidae) that was investigated using mating experiments and phylogenetic analyses of the mtDNA COI (658 bp) and 16S rRNA (435 bp) regions, and nDNA SSR (13 loci) and its genome-wide SNPs (11,241 SNPs). The results of our phylogenetic analyses based on their mtDNA dataset and the genome-wide SNPs dataset strongly supported the paraphyly of the Japanese populations. Therefore, it is suggested that their ancestral lineage which being distributed in the Japanese Archipelago subsequently migrated to the Eurasian Continent (i.e., "back-dispersal" occurred). Furthermore, the results of the mating experiments suggested that among A. japonicus, even between closely related lineages, pre-mating reproductive isolation has been established by the differentiation of copulatory organ morphologies. In contrast, pre-mating reproductive isolation is not established in the absence of the differentiation of copulatory organ morphologies, even if genetic differentiation is prominent. These results suggested that their phylogenetic distance does not predict pre-mating reproductive isolation. Furthermore, in the present study, we present a clear example of pre-mating reproductive isolation driving speciation between closely related lineages.

We developed microsatellite markers for Appasus japonicus (Heteroptera: Belostomatidae). This belostomatid bug is distributed in East Asia (Japanese Archipelago, Korean Peninsula and mainland China) and often listed as an endangered species in the Red List or the Red Data Book at the national and local level in Japan. Here, we describe twenty novel polymorphic microsatellite loci developed for A. japonicus, and marker suitability was evaluated using 56 individuals from four A. japonicus populations (Nagano, Hiroshima and Yamaguchi prefectures, Japan, and Chungcheongnam-do, Korea). The number of alleles per locus ranged from 1 to 12 (mean = 2.5), and the average observed and expected heterozygosity and fixation index per locus were 0.270, 0.323 and 0.153, respectively. In addition, a population structure analysis was conducted using the software STRUCTURE, and its result suggested that the 20 markers described here will be useful for investigating the genetic structure of A. japonicus populations, which should contribute to population genetics studies of this species.

DNA barcoding has been actively used as a method for species identification, and it will become an increasingly important method in the future. However, DNA barcoding can occasionally encounter a major problem, namely “nuclear mitochondrial DNA pseudogenes (NUMTs)”. In this paper, we report the discovery of a pseudogene in the mitochondrial COI region from aquatic heteropterans. PCR with Folmer’s universal primer set produced two different lengths of DNA sequences: a standard 658 bp sequence and a slightly shorter 652 bp sequence. The presence of an “indel” and “stop codon” in the shorter sequence made them separable. We recommend using the “HCOoutout” primer as a downward primer for amplification of the COI region of aquatic heteropterans, especially corixid water bugs.

DNA barcoding is a powerful tool that provides rapid, accurate, and automatable species identification by using standardized genetic region(s). It can be a powerful tool in various fields of biology such as for revealing the existence of cryptic species and/or rare species and in environmental science such as when monitoring river biota. Biodiversity reduction in recent times has become one of the most serious environmental issues on a worldwide scale. DNA barcoding techniques require the development of sets of universal PCR primers for DNA metabarcoding. We tried to develop universal primer sets for the DNA barcoding of all insect groups. In this study, we succeeded in designing not only universal primer sets for DNA barcoding regions of almost all insects, which were designed to include a hypervariable site between highly conserved sites, but also primer sets for longer fragment sequences for registration in a database. We confirmed successful amplification for 14 orders, 43 families, and 68 species with DNA barcoding in the mtDNA 16S rRNA region, and for 13 orders, 42 families, and 66 species with DNA barcoding in the mtDNA 12S rRNA region. A key feature is that the DNA fragments of the DNA barcoding regions amplified by these primer sets are both short at about 200-bp, and longer fragment sequences will increase the level of data registration in the DNA database. Such resulting database enhancements will serve as a powerful tool for increasingly accurate assessment of biodiversity and genetic diversity.

We developed microsatellite markers for Appasus japonicus (Hemiptera: Belostomatidae). This belostomatid bug is distributed in East Asia (Japanese Archipelago, Korean Peninsula, and Mainland China), and often listed as endangered species in the ‘Red List’ or the ‘Red Data Book’ at the national and local level in Japan. Here we describe twenty novel polymorphic microsatellite loci developed for A. japonicus, and marker suitability was evaluated on 56 individuals from four A. japonicus populations (Nagano, Hiroshima, and Yamaguchi prefecture, Japan, and Chungcheongnam-do, Korea). The number of alleles per locus ranged 1–12 (mean = 2.5), and average observed and expected heterozygosity, and fixation index per locus were 0.270, 0.323, and 0.153, respectively. The 20 markers described here will be useful for investigating the genetic structure of A. japonicus populations, which can contribute in population genetics studies of this species.

Oviparous, ovoviviparous and viviparous reproduction are interesting subjects for understanding animals' evolutionary pathways and adaptation to their life history and habitat conditions. In this study, we examined the reproductive mode of the ovoviviparous mayfly Cloeon dipterum, particularly comparing embryogenesis between hand-pairing and unmated females' common oviduct. Our study suggested that the high developmental rate of C. dipterum observed in a recent study could be ascribed to their absorption of unfertilized eggs. The developmental rates of hand-paired females were almost 100%, while their egg-bearing numbers were lower than those of virgin females. Thus, such reduced egg numbers suggest the maternal absorption of unfertilized eggs. This trait is thought to have evolved with the ovoviviparous characteristics of C. dipterum. We identified the basis of the irregularity of this species exhibiting such a high (i.e., 100%) developmental rate in our previous recent study.

InSnZnO thin-film transistors (ITZO TFTs), having high carrier mobility, guarantee the benefits of potential applications in the next generation of super-high-definition flat-panel displays. However, the impact of photo-excitation on the leakage current and negative bias stress (NBIS) of ITZO TFTs must be further explored. In this study, the ITZO thickness (TITZO) is designed to tailor the initial performance of devices, especially for the 100 nm TITZO TFT, producing excellent electrical properties of 44.26 cm2V&minus, 1s&minus, 1 mobility, 92 mV/dec. subthreshold swing (SS), 0.04 V hysteresis, and 3.93 &times, 1010 ON/OFF ratio, which are superior to those of the reported ITZO TFTs. In addition, incident light coupled with tunable photon energy is introduced to monitor the leakage current of various TITZO devices. The OFF-current results demonstrate that under the identical photon energy, many more electrons are photo-excited for the thicker TITZO TFTs. NBIS-induced Vth shift and SS deterioration in all TFTs are traced and analyzed in real time. As the TITZO thickens to near Debye length, the degree of degradation is exacerbated. When the thickness further increases, the notorious instability caused by NBIS is effectively suppressed. This study provides an important research basis for the application of ITZO-based TFTs in future displays.

Oviparous, ovoviviparous and viviparous reproduction are interesting subjects for understanding animals' evolutionary pathways and adaptation to their life history and habitat conditions. In this study, we examined the reproductive mode of the ovoviviparous mayfly

Thin-film transistor (TFT) devices composed of metal oxide semiconductors have attracted tremendous research attention globally in recent years. Owing to their ability to offer mobility, metal oxide semiconductor materials can enable high-performance TFTs for next-generation integrated display devices. Nevertheless, further breakthroughs of metal oxide TFTs are mainly obstructed by their long-term variability, the reason for which is not yet fully understood. Herein, TFTs based on InSnZnO (ITZO) with various thicknesses (TITZO) were prepared and their long-term stabilities under test temperatures and drain current stress were investigated. The results indicate that ITZO TFTs exhibit outstanding electrical properties regardless of the TITZO, including a high saturated mobility of over 35 cm2V&minus, 1s&minus, 1 and sharp subthreshold swing. Note that the transfer and output characteristic curves of the device with a thick TITZO of 100 nm express an abnormal current surge when high gate and drain voltages are exerted, which is attributed to the floating body effect, caused when the imposed electric field induces impact ionization near the drain side. More interestingly, these drain current stress results further suggest that the abnormal shift behavior of the electrical properties of the ITZO TFTs with a TITZO of greater than 75 nm is observed to deteriorate gradually with increasing temperature and drain current bias. This study addresses that such a degradation effect should be restrained for the operation of high-mobility devices.

In the present study, we add genetic data of the mayfly

There is a great deal of demand for the construction of transplantable liver grafts. Over the last decade, decellularization techniques have been developed to construct whole liver tissue grafts as potential biomaterials. However, the lack of intact vascular networks, especially sinusoids, in recellularized liver scaffolds leads to hemorrhage and thrombosis after transplantation, which is a major obstacle to the development of transplantable liver grafts. In the present study, we hypothesized that both mechanical (e.g., fluid shear stress) and chemical factors (e.g., fibronectin coating) can enhance the formation of hierarchical vascular networks including sinusoid-scale microvessels. We demonstrated that perfusion culture promoted formation of sinusoid-scale microvessels in recellularized liver scaffolds, which was not observed in static culture. In particular, perfusion culture at 4.7 ml/min promoted the formation of sinusoid-scale microvessels compared to perfusion culture at 2.4 and 9.4 ml/min. In addition, well-aligned endothelium was observed in perfusion culture, suggesting that endothelial cells sensed the flow-induced shear stress. Moreover, fibronectin coating of decellularized liver scaffolds enhanced the formation of sinusoid-scale microvessels in perfusion culture at 4.7 ml/min. This study represents a critical step in the development of functional recellularized liver scaffolds, which can be used not only for transplantation but also for drug screening and disease-modeling studies. Statement of Significance Decellularized liver scaffolds are promising biomaterials that allow production of large-scale tissue-engineered liver grafts. However, it is difficult to maintain recellularized liver grafts after transplantation due to hemorrhage and thrombosis. To overcome this obstacle, construction of an intact vascular network including sinusoid-scale microvessels is essential. In the present study, we succeeded in constructing sinusoid-scale microvessels in decellularized liver scaffolds via a combination of perfusion culture and surface coating. We further confirmed that endothelial cells in decellularized liver scaffolds responded to flow-derived mechanical stress by aligning actin filaments. Our strategy to construct sinusoid-scale microvessels is critical for the development of intact vascular networks, and addresses the limitations of recellularized liver scaffolds after transplantation.

We have developed pseudo-CMOS circuits using α-ITZO TFTs. The pseudo-CMOS circuits have more excellent circuit characteristics than the conventional circuits. Either of the two pseudo-CMOS circuits should be selected on demand by considering whether the static or dynamic characteristic is important. These results are useful to integrate driver circuits into FPDs.

Ultrafast excited state dynamics of the short fucoxanthin homolog with four conjugated double bonds and its allene-modified analog in various solvents have been studied by femtosecond pump-probe spectroscopy. The results clarified that the short fucoxanthin homolog exhibits a strong intramolecular charge transfer character in an excited manifold even in a nonpolar solvent. Then, the data show that a modification of the allene-group induced the lifetime shortening of the lowest singlet state of the short fucoxanthin homolog. This implies that the allene-group enhances the ICT character of the short fucoxanthin homolog.

C 29 -peridinin is a synthetic analogue of the important, naturally-occurring carotenoid, peridinin, found in several marine algal species. C 29 -peridinin has five conjugated carbon–carbon double bonds compared to eight possessed by peridinin and also lacks the methyl group functionalities typically present along the polyene chain of carotenoids. These structural modifications lead to unique excited state properties and important insights regarding the factors controlling the photophysics of peridinin and other carbonyl-containing carotenoids, which are critical components of the light-harvesting systems of many photosynthetic organisms.

In the present study, we add genetic data of the mayfly Cloeon dipterum collected from the Japanese Islands to the established molecular phylogenetic knowledge in the mitochondrial COI gene of Cloeon mayflies. Cloeon dipterum is a typical cosmopolitan species that includes six intraspecific haplotype groups. The present phylogenetic analysis revealed that haplotypes of the Japanese C. dipterum constitute a seventh group together with a haplotype from Korea. This East Asian group forms a sister group with previously known European and North American haplotype groups (i.e., the clade CT1 to CT3). The present phylogenetic analysis further revealed the occurrence of two described species (C. dipterum and Cloeon ryogokuensis) and possibly three species (Cloeon sp. 1 to 3) in Japan. Consideration is given to the degree of genetic differentiation, divergence time, and differentiation process among these seven genetic groups.

Fucoxanthin is an essential pigment for the light-harvesting of aquatic algae. It exhibits high energy transfer efficiencies to Chl a (>80%) as well as peridinin (>95%). In order to verify the generality and specificity of the noticeable observation on the ICT excited energy state character, which was found in the study of peridinin, we achieved the straightforward synthesis of a series of fucoxanthin short-chain derivatives via the modified-Julia olefination with the aldehyde half segment possessing a β,γ-epoxyketone function. The established method was successfully applied to the synthesis of the epoxy olefin derivative as an allene modified fucoxanthin analogue.

We investigated the magnetoconductivity ∆ σ ( H , T ) defined by a function of magnetic field H and temperature T for three-dimensional indium–gallium–zinc oxide films in the resistivity ρ range of 0.076 × 10 − 3 Ω m ≤ ρ (2.0 K) ≤ 0.55 × 10 − 3 Ω m. Here, ∆ σ ( H , T ) is the ∆ σ ( H , T ) ≡ 1 / ρ ( H , T ) − 1 / ρ (0, T ). With increasing ρ , the contribution ∆ σ EEI due to the electron–electron interaction (EEI) effect overcomes the contribution ∆ σ WL due to the weak localization (WL) effect. The sign of ∆ σ ( H ) = ∆ σ EEI + ∆ WL changes from positive to negative with increasing magnetic field, particularly at low temperatures. To perform a systematic investigation of ∆ σ EEI , we obtained the contribution of ∆ σ EEI using the relation ∆ σ EEI ( H , T ) = ∆ σ exp. ( H , T ) − ∆ σ WL theo. ( H , T ), where ∆ σ WL theo. ( H , T ) is estimated by fitting the WL theory to data at low magnetic fields. It was found that i) Δ σ EEI H T / T as a function of H / T for each film collapses onto a single universal curve at a magnetic field of up to 5 T and in the temperature range between 2.0 and 50 K. ii) From the analyses of Δ σ EEI H T / T in the high and low H / T regions with the EEI theory, the screening factors F ∆ σ , H and F ∆ σ ,L were estimated, respectively. iii) The F ∆ σ , H values satisfy the theoretical prediction as 0 F ρ , the magnitudes of both F ∆ σ , H and F ∆ σ ,L essentially decrease to approach 0 at ρ c ≈ 1.3 × 10 − 3 Ω m, where the metal–insulator transition is suggested to occur.

We have investigated thermal distribution of an amorphous InSnZnO thin-film transistor (TFT) under voltage stress by using thermal imaging system. To clarify an influence of only self-heating phenomenon on reliability, we have focused on a channel scale dependence of heating. As the result, heating effect were strongly depended on channel scale and showed two types of dependences on channel length and width. When positive bias stress was applied to TFT, severe threshold voltage shift and high heating temperature were observed for wider TFT. Moreover, reliability under voltage stress was seems to be affected by accumulation of heating in wider TFT. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Hysteresis of InGaZnO thin-film transistor (IGZO TFT) under negative-bias with illumination stress (NBIS) was investigated using double sweeping gate voltage (VGS) mode. We found that hysteresis of IGZO TFT was significantly enlarged by the NBIS with large negative gate voltage stress. On-current and S value in forward measurements started to show degradation under large-negative VGS stress due to acceptor-like defect creation; on the other hand, transfer curves in reverse measurements shifted to a positive VGS direction without S degradation. As a result of NBIS degradation, huge hysteresis can be observed. To explain the change in hysteresis under NBIS, degradation model consisting of acceptor-like bistable defects is proposed.

Trap states in α-ITZO TFTs are analyzed using the dependences of the trap densities on the channel thickness. Utilizing extraction methods of trap densities in the film, at the front and back interfaces it is suggested that the trap states are not distributed in the film but localized at the interface

The use of environmental DNA (eDNA) has recently been employed to evaluate the distribution of various aquatic macroorganisms. Although this technique has been applied to a broad range of taxa, from vertebrates to invertebrates, its application is limited for aquatic insects such as aquatic heteropterans . Nepa hoffmanni (Heteroptera: Nepidae) is a small (approx. 23 mm) aquatic heteropteran that inhabits wetlands, can be difficult to capture and is endangered in Japan. The molecular tool eDNA was used to evaluate the species distribution of N. hoffmanni in comparison to that determined using hand-capturing methods in two regions of Japan. The eDNA of N. hoffmanni was detected at nearly all sites (10 eDNA-detected sites out of 14 sites), including sites where N. hoffmanni was not captured by hand (five eDNA-detected sites out of six captured sites). Thus, this species-specific eDNA technique can be applied to detect small, sparsely distributed heteropterans in wetland ecosystems. In conclusion, eDNA could be a valuable technique for the detection of aquatic insects inhabiting wetland habitats, and could make a significant contribution to providing distribution data necessary to species conservation.

In order to investigate the relation among the superconducting transition T c , carrier density n , resistivity ρ and the microstructure in the polycrystalline (In 2 O 3 ) 1− x –(ZnO) x films, we prepared specimen films by post annealing of amorphous films with x = 0.025 at various annealing temperature T a and for annealing time t a = 1 h and 4 h. As for microstructures, we have investigated the distribution of elements by scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS). We have found followings: (1) The annealed films clearly show the superconductivity of which T c depends on T a , t a and n . This indicates that the superconductivity is determined by the combination of crystallinity and carrier density. (2) The data on STEM–EELS spectra mapping of indium plasmon indicate that droplets of the pure indium phase exist inside a film, where the distribution of these droplets dispersed. Therefore, it seems that droplets do not form an electrical conducting path, that is, it is possible that observed superconductivity is due to intrinsic characteristic of polycrystalline (In 2 O 3 ) 1− x –(ZnO) x films.

The electronic structural analysis of the conductive transparent films was carried out using bulk sensitive hard X-ray photoelectron spectroscopy (HAXPES). The In 2 O 3 -ZnO film has amorphous structure before and after annealed, and the conduction band spectrum around Fermi level showed the similar spectra with that of as-deposited amorphous In 2 O 3 film. In these amorphous films, the conduction band minimum locates at the deeper level than the crystalline In 2 O 3 film. The electronic state which comes from randomness of amorphous structure possibly exists around this level or below. These electrons are expected to act as scattering center. We concluded that the electron mobility depends on the density of this electronic state.

We have investigated the relation among ρ – T characteristics, superconductivity, annealing conditions and the crystallinity of polycrystalline (In 2 O 3 ) 1− x –(ZnO) x films. We annealed as-grown amorphous films in air by changing annealing temperature and time. It is found that the films annealed at 200 °C or 300 °C for a time over 0.5 h shows the superconductivity. Transition temperature T c and the carrier density n are T c n ≈ 10 25 –10 26 m −3 , respectively. Investigations for films with x = 0.01 annealed at 200 °C have revealed that the T c , n and crystallinity depend systematically on annealing time. Further, we consider that there is a suitable annealing time for sharp resistive transition because the transition width becomes wider with longer annealing times. We studied the upper critical magnetic field H c2 ( T ) for the film with different annealing time. From the slope of dH c2 / dT for all films, we have obtained the resistivity ρ dependence of the coherence length ξ (0) at T = 0 K.

We have systematically investigated the temperature dependence of resistivity p and Hall coefficient R H of indium zinc oxide films with thickness d=350 nm in the temperature range 2.0 K to 300 K. Specimen films with p≃3-17 μΩ m (300 K) show metallic characteristics (pαT) at temperatures above 100 K. At low temperatures below 20 K, the resistivity slightly increases with decreasing temperature because of the quantum effects in disordered systems. By eliminating carefully quantum effects p quanta and the residual resistivity po, we have found that the resistivity changes in the form of pα poT 2 at temperatures below ≃100 K. This characteristic indicates the existence of resistivity pel-ph-imp due to the interference effect between the impurity scattering and the electron-phonon scattering. It has been found that the temperature dependence of p(T)for all present films agrees well with the sum of the Bloch-Griineisen term ρ el-Ph =βF(T,ΘD) and the interference term ρ el-ph-imp = B el-Ph-imp G(T,ΘD) in a temperature region 20 K to 300 K. From analyses, regarding the coefficients β, B el-Ph-imp , and the Debye temperature Θ D as fitting parameters, we obtain the Θ D ≃970-1060 K and the longitudinal sound velocity νl ≃ 14,000 m/s under some assumptions.

Representative transparent conductive oxide films, such as tin-doped indium oxide (ITO) and indium–zinc oxide (IZO) films, were deposited by dc magnetron sputtering using corresponding oxide targets under various total gas pressures (Ptot) ranging from 0.3 to 3.0 Pa. The ITO films deposited at a Ptot lower than 0.7 Pa were polycrystalline and were found to have a large compressive stress of about 1.5 ×109 Pa, whereas the ITO films deposited at 1.5–3.0 Pa were amorphous and had a low tensile stress. In contrast, all the IZO films deposited at a Ptot range of 0.3–3.0 Pa showed an entirely amorphous structure, where the compressive stress in the IZO films deposited at a Ptot lower than 1.5 Pa was lower than that in the ITO films. Such compressive stress was considered to be generated by the atomic peening effect of high-energy neutrals (Ar0) recoiled from the target or high-energy negative ions (O-) accelerated in the cathode sheath toward the film surface.

Degradation by Joule heating of the thin-film transistors (TFTs) is one of the important issues for realizing next-generation displays. We have investigated the thermal distribution on the channel region of transparent amorphous oxide semiconductor TFT in pulse operation using an infrared imaging system. We also discussed the relationship between the self-heating temperature and the degradation.

In a previous work, we reported the high field effect mobility of ZnO-doped In2O3 (IZO) thin film transistors (TFTs) irradiated by excimer laser annealing (ELA) [M. Fujii et al., Appl. Phys. Lett. 102, 122107 (2013)]. However, a deeper understanding of the effect of ELA on the IZO film characteristics based on crystallinity, carrier concentrations, and optical properties is needed to control localized carrier concentrations for fabricating self-aligned structures in the same oxide film and to adequately explain the physical characteristics. In the case of as-deposited IZO film used as the channel, a high carrier concentration due to a high density of oxygen vacancies was observed; such a film does not show the required TFT characteristics but can act as a conductive film. We achieved a decrease in the carrier concentration of IZO films by crystallization using ELA. This means that ELA can form localized conductive or semi-conductive areas on the IZO film. We confirmed that the reason for the carrier concentration decrease was the decrease of oxygen-deficient regions and film crystallization. The annealed IZO films showed nano-crystalline phase, and the temperature at the substrate was substantially less than the temperature limit for flexible films such as plastic, which is 50°C. This paves the way for the formation of self-aligned structures and separately formed conductive and semi-conductive regions in the same oxide film.

Amorphous indium–gallium–zinc oxide (a-IGZO) films were deposited by DC magnetron sputtering and post-annealed in air at 300–1000 °C for 1 h to investigate the crystallization behavior in detail. X-ray diffraction, electron beam diffraction, and high-resolution electron microscopy revealed that the IGZO films showed an amorphous structure after post-annealing at 300 °C. At 600 °C, the films started to crystallize from the surface with c-axis preferred orientation. At 700–1000 °C, the films totally crystallized into polycrystalline structures, wherein the grains showed c-axis preferred orientation close to the surface and random orientation inside the films. The current–gate voltage (I d–V g) characteristics of the IGZO thin-film transistor (TFT) showed that the threshold voltage (V th) and subthreshold swing decreased markedly after the post-annealing at 300 °C. The TFT using the totally crystallized films also showed the decrease in V th, whereas the field-effect mobility decreased considerably.