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A high‐density surface‐wave plasma source is used to deposit hexagonal boron nitride (hBN) films in a gas mixture of He, H2, N2, Ar, and BF3 under a high ion flux condition using low‐energy ion irradiation. The ion energy is controlled between around zero and 100 eV by applying a negative or positive bias voltage to a substrate, while the ion flux is increased by locating a substrate upstream in the diffusive plasma. For ion energies above ∼37 eV, the structure of the films depends upon ion energy more than substrate temperature, typical of subplantation processes. As a result, the structural order and crystallinity of sp2‐bonded phase in the films characterized by Fourier transform infrared spectroscopy and X‐ray diffraction are increased with decreasing ion energy, while the mass density of the films characterized by X‐ray reflectivity is retained relatively high with a slight dependence upon ion energy. [ABSTRACT FROM AUTHOR]

In order to rationalize the homologous nature of the Peierls stress reported in a previous paper (Y. Kamimura et al., Acta Mater. 61 (2013) 294–309), we have calculated numerically the Peierls stresses via the Peierls-Nabarro model (P-N model) of the planar core dislocation, using calculated ab-initio γ -surface for a variety of crystals: fcc metals, bcc metals, NaCl type crystals, CsCl type ionic crystals and various tetrahedrally coordinated crystals. The obtained γ- surfaces for the same group of crystals are found to have similar shape and height when normalized by materials parameters, indicating homologous nature. Except for some very soft crystals ( τ P exp / G ≪ 1 × 10 −4 ), the calculated Peierls stresses for majority of crystals ( τ P exp / G > 1 × 10 −4 ) are shown, for the first time, to have a correlation with experimental ones reflecting the homologous nature of the γ -surface, although the former are generally larger than the latter by half an order on the average, with an exception of bcc metal in which the strain field of the controlling screw dislocation is known to be non-planar. For very soft crystals, the calculated Peierls stresses are orders of magnitude larger than experimental ones; possible origins of this large discrepancy are discussed. [ABSTRACT FROM AUTHOR]

Ovoviviparity and viviparity have evolved independently multiple times in animals. Although females exhibit extensive parental care of their eggs, (ovo)viviparity has only been reported in a few species of free-living, nonepizoic earwigs. In contrast, to date, all the studied members of families Arixeniidae and Hemimeridae, which live on mammals, are viviparous. We herein report ovoviviparity in the tropical earwig species, Spongovostox semiflavus (Bormans, 1894) (Forficuloidea: Spongiphoridae: Spongiphorinae). We observed that females of this species retain well-developed embryos within the ovaries and then lay them with complete egg envelopes just before hatching. An average of 9.4 embryos concurrently developed in a female's body. A similar condition has been reported for only one other species Marava arachidis (Yarsin, 1860), in the subfamily Spongiphorinae. Without additional mating, Spo. semiflavus females produced at least three clutches, consisting of an average of nine offspring within a period of 14-27 d. Both Spo. semiflavus and M. arachidis males are characterized by elongated male genitalia that are more than twice as long as their body lengths. Interestingly, elongated male genitalia are also present in the two other spongiphorids for which (ovo)viviparity has been reported. We discuss the causes of the potential convergence of the evolution of the male genital structure and the development of (ovo)viviparity in females. [ABSTRACT FROM AUTHOR]

Abstract: Peierls stresses (τ P) of dislocations of 66 slip systems in 52 crystals were estimated from experimental data either by direct extrapolation of the critical resolved shear stress (τ c) vs. temperature curve to absolute zero temperature, or from the T 0 value at which the temperature dependence of τ c vanishes, based on the kink-pair formation enthalpy, which is a function of τ P, described by the line tension model of the dislocation. The normalized τ P/G (G is the shear modulus) values are distributed over four orders of magnitude, but τ P/G values for a group of crystals with the same crystal structure are within an order of magnitude, indicating a homologous nature of τ P in crystals. In order to compare the results with the Peierls–Nabarro (P–N) formula generalized to any dislocation character, log(τ P/G) values were correlated with crystal parameters. In this generalized P–N plot, most of the plots deviate downwards from the Huntington relation (a revised, original P–N relation) and the results of the discretized P–N models of Ohsawa et al. (Ohsawa K, Koizumi H, Kirchner HOK, Suzuki T. Philos Mag A 1994;69:171), with the deviation becoming larger at large h/δ value, where h is the lattice spacing of the glide plane, and δ is the period of the lattice in the direction of the dislocation glide. In the plot, there is a tendency that the stronger the covalent character, the higher the τ P/G value, reflecting the general tendency of the normalized theoretical shear strength of crystals. [Copyright &y& Elsevier]

Sex allocation theories provide excellent opportunities to investigate not only the extent to which individuals' behaviour is adaptive, but also how they use relevant information for their decision-making. Here, we investigated whether female parasitoid wasps recognize the sex ratios of other females and adjust their laying sex ratios accordingly. Specifically, we tested the prediction of reciprocal cooperation over sex allocation. Theory predicts more female-biased (cooperative) sex ratios than in the interest of individual benefit, when a restricted number of ovipositing females interact for a long period and their offspring mate within the natal patch. This is because the female-biased sex ratio reduces competition for mates among the male offspring of the females and increases the overall reproductive productivity of the patch. In this case, females would be expected to respond to more even (noncooperative) sex ratios by others and to retaliate by also producing a less female-biased sex ratio to avoid exploitation by defectors. However, contrary to this prediction, our experiment using a sterile male technique showed that female Melittobia australica did not change their offspring sex ratios in response to the sex ratios produced by other females. This suggests that their extremely female-biased sex ratios cannot be explained by reciprocity. A meta-analysis of studies examining sex recognition ability in parasitoid wasps also did not support the predicted pattern of relevant sex ratio adjustment, suggesting that parasitoid females do not possess this ability. Here, we discuss the conditions necessary for the evolution of reciprocity linked to recognition ability. [ABSTRACT FROM AUTHOR]

Abstract: Male and female genitalia generally show a rapid evolutionary rate, which raises the problems related to homologization and the determination of the polarities of evolutionary changes. In earwigs (Dermaptera), multiple or branched female sperm-storage organs (spermathecae) have been reported for members of the Karschiellidae, Pygidicranidae, and Diplatyidae, collectively termed the “basal” Dermaptera. Whether the complicated spermathecae represent a plesiomorphy or an apomorphy has not been resolved. Here I report the occurrence of multiple or branched spermathecae in gamma-irradiated samples of two earwig species, Euborellia plebeja (Dohrn, 1863) (Anisolabididae) and Proreus simulans (Stål, 1860) (Chelisochidae), which belong to the “higher” Dermaptera (Apachyidae, Labiduridae, Anisolabididae, Spongiphoridae, Chelisochidae, and Forficulidae). Females belonging to the higher Dermaptera normally have a single-unbranched spermatheca. I discuss examples of possible atavisms in relation to the evolutionary pathways of spermathecal morphology. Possible atavisms in the number of male organs for sperm transfer (virgae) are also reported. [Copyright &y& Elsevier]

High-resolution transmission electron microscopy (HRTEM) images are simulated for the core structures of 1/2[111] screw dislocations in body centered cubic (bcc) metals to examine the possibility of determining the core structure experimentally by HRTEM. Two types of cores are studied: a polarized core and an isotropic one. For the model crystals containing the screw dislocations with the two types of cores, HRTEM images are calculated by a multi-slice method with the incident beam parallel to the [1 &1macr; 0] direction that is perpendicular to the direction of the dislocation line. A qualitative difference between the images of the two types of cores is detected; for the isotropic core the image always possesses the two-fold symmetry, irrespective of the defocus value, while for the polarized core it does not. This fact suggests that HRTEM experiments with the incident beam parallel to the [1 &1macr; 0] direction can distinguish between the two types of core. [Copyright &y& Elsevier]

Forficulina, the largest suborder of Dermaptera (earwigs), has eight families. In five families (Pygidicranidae, Diplatyidae, Anisolabididae, Apachyidae, and Labiduridae), the males have two penises, whereas the males of the other three families (Spongiphoridae, Chelisochidae, and Forficulidae) have a single penis. Several cladograms have been proposed for Forficulina. However, those systems are constructed mainly from observations of male genital morphology and outstandingly inconsistent. This study reconstructed an earwig phylogeny with representatives of seven families (excluding Apachyidae) by using partial sequences of the mitochondrial 16S and nuclear 28S rRNA genes, sequences that are independent of genital evolution. To avoid difficulties caused by outgroup-rooting for a deep phylogeny, ingroup relationships were first established as unrooted trees based on the 16S, 28S, and combined data sets. The resulting affinities of the earwig families supported several superfamilies, such as Forficuloidea (single-penis families) and Pygidicranoidea (Pygidicranidae + Diplatyidae). Inclusion of the outgroup (Glylloblattodea and Blattodea) did not distort the established ingroup relationships. However, the root position varied according to the genes and outgroup taxa used. Kishino-Hasegawa tests based on the maximum likelihood criterion suggested that the common ancestor of contemporary Forficulina had twin penises, each with one gonopore. [ABSTRACT FROM AUTHOR]

Abstract We constructed a sex allocation model for local mate competition considering the asymmetry of competitive abilities among sons. This model assumes two females of a parasitoid wasp oviposit on the same host in sequential order. The evolutionarily stable strategy will be in either Stackelberg or Nash equilibrium, depending on whether the females can recognize their opponent's sex ratio or not, respectively. The Nash equilibrium predicts the second female produce more males than the first. If the second female is able to know and respond to the strategy of the first (a Stackelberg equilibrium), the first will decide an optimal sex ratio assuming that the second reply to it. Under such an assumption, our model predicts that not producing sons is adaptive for the second female when the sons she produces have low competitive ability. Males of parasitoid wasps Melittobia spp. are engaged in lethal male–male combat, indicating large asymmetry in mating success among sons. If females have the ability to recognize their opponent's sex ratio, our model suggests that the severe lethal male–male combat may be one factor explaining their extremely female-biased sex ratio that is unexplainable by pre-existent models. [ABSTRACT FROM AUTHOR]

The temperature dependence of the yield stress tau c of four bcc transition metals alpha-Fe, Nb, Mo and Ta, and an alkali metal K as well, follows a scaling relation of tau c/ tau P against kT/b3(tau PKT)1/2, where tau P is the Peierls stress, b the length of the Burgers vector and KT the line tension factor for a screw dislocation calculated for elastic anisotropy. The same relation seems to apply for the other three bcc transition metals V, Cr and W, suggesting its general applicability at least for low strain rates (about 10-4 s-1). The result implies that the plasticity of bcc metals is characterized by only one non-elastic parameter, the Peierls stress tau P. [ABSTRACT FROM AUTHOR]

Examines the whole field spatial frequency analysis of double or multiple exposed particle image velocimetry (PIV) images. Role of spatial frequency filtering in reconstructing a velocity contour of map flows; Restriction of technique to simple flows; Application of wavelet analysis to the field spatial frequency analysis of PIV images.

• Structure and leakage current characteristics of hexagonal boron nitride films are studied. • The crystallinity and order of sp2 structure are retained for the change in B-to-N ratio. • The resistivity increases largely by increasing B-to-N ratio closer to the stoichiometry. • A lower density of defect states related to the boron vacancy decreases the leakage current. Sp2-bonded boron nitride (BN) films with different B-to-N ratios are deposited on Si and Ni substrates at an ion impact energy of around 50 eV by surface-wave plasma enhanced chemical vapor deposition. The overall crystallinity and order of sp2 bonding structure are almost retained with increasing BF 3 /N 2 gas flow ratio in the plasma, while the B-to-N ratio in the film is varied from 0.89 to 0.96. The electrical resistivity of the films measured at room temperature for Ni-BN-Ni structures shows a large increase up to the order of 1010 Ω cm when the B-to-N ratio in the film is increased closer to the stoichiometry due to a lower density of defect states related to the boron vacancy. The characteristics of leakage current vs. applied bias voltage show Ohmic behavior at low fields and non-Ohmic behavior governed by the thermionic emission mechanism at high fields for any B-to-N ratio. [ABSTRACT FROM AUTHOR]

Intermetallic alloys with B2 structure and dual-phase alloys of the B2 phase and an icosahedral (i-) phase have been produced, and their mechanical properties have been investigated. Vickers hardness measurements and compression experiments have shown that the dual-phase alloys have considerably higher strength than that of the B2 single-phase alloy up to a high temperature of around 750?K. The dual-phase alloys have also exhibited much better ductility than i-single-phase alloys. One possibility to be pointed out is that we can further design a high-strength and good-ductility alloy by tuning the volume fraction, size and morphology of the i-phase precipitates. [ABSTRACT FROM AUTHOR]

An interpretation for the temperature dependence of the plastic flow stress of III-V compounds is presented, invoking only non-dissociated screw dislocations. With the aid of the Stillinger-Weber potential for the interatomic interaction, the Peierls potential of a non-dissociated screw dislocation is deduced in twodimensional space normal to the dislocation line. A saddle-point configuration and the formation energy of a kink pair are calculated in three-dimensional space. The relation obtained between the flow stress τ[sub c] and temperature T under a constant strain rate describes the experimental τ[sub c] T relation of III-V compound well: a strong T dependence at high τ[sub c] and low T, a stronger T dependence at low τ[sub c] and high T, and a plateau-like τ[sub c] at intermediate T. The hump in the τ[sub c] T relation is interpreted as a transition between different paths of the non-dissociated screw dislocation: a planar path and a zigzag path in the (111) plane. [ABSTRACT FROM AUTHOR]

The local electrical resistivities in deformed n-GaP have been measured by scanning spreading resistance microscopy (SSRM). The SSRM images show chainlike alignments of spots with high resistivity along the slip direction. These spots can be attributed to carrier-depletion around a charged dislocation. From the observed spot size, the line charge density of the dislocations has been estimated to be 0.4–0.9e/b, where b denotes the magnitude of the Burgers vector. The estimated value of line charge density has been discussed in relation with the dislocation core structure. [ABSTRACT FROM AUTHOR]

The giant dielectric response in Cd-doped CaCu3Ti4O12 ceramics was studied over the temperature range from 40 K to 850 K. In all CaxCd1-xCu3Ti4O12 system, two broad dielectric dispersions around 150 K and 650 K and a dielectric anomaly at T1 were observed. The T1 decreases linearly with increasing Cd-molar ratio (x) from 733 K for CaCu3Ti4O12 to 632 K for CdCu3Ti4O12. CdCu3Ti4O12 exhibits ε ∼ 0.6 × 104 at room temperature and 1.4 × 104 at T1 (1 MHz). This evidence shows CdCu3Ti4O12 is still a member of high-dielectric materials in contrast to a previous work (ε ∼ 409 at 100 kHz). [ABSTRACT FROM AUTHOR]

Dissolution patterns caused by anodic etching of an Al–Pd–Mn icosahedral quasicrystal and chemical etching of an Al–Cu–Co decagonal quasicrystal were examined by optical and electron microscopy as well as by atomic force microscopy. Appropriate etching treatments of these quasicrystals, i.e. the anodic etching of the Al–Pd–Mn quasicrystal in a solution of CH3OH–HNO3, and the chemical etching of the Al–Cu–Co quasicrystal in a solution of HF–HNO3–H2O resulted in occurrence of dissolution patterns composed of a number of well-facetted micropits (and hillocks for the Al–Cu–Co alloy as well) on low-indexed surfaces of the specimens. The morphological features of these etch-figures are discussed in relation to the internal structural symmetries. [Copyright &y& Elsevier]

Abstract: Optical properties of fresh dislocations, (a/3)[112¯0]-type edge dislocations on the (11¯00) prismatic plane, introduced into GaN by plastic deformation at elevated temperatures were investigated by photoluminescence and optical absorption measurements. Plastic deformation acts as an effective passivation, leading to remarkable reduction of near-band-edge photoluminescence intensity centered at 3.48eV and noticeable red-shift of the optical absorption edge. In a model of the Franz–Keldysh effect, the induced edge dislocations posses nonradiative trap sites around 3e/c along their core, resulting in the reduction of free-carrier concentration. Also, the induced dislocations give rise to some luminescence peaks in the energy range 1.7–2.4eV, differing from the yellow luminescence, which implies the formation of radiative recombination centers by the dislocations. [Copyright &y& Elsevier]