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Gallium nitride (GaN) is one of the most technologically important semiconductors and a fundamental component in many optoelectronic and power devices. Low-resistivity GaN wafers are in demand and actively being developed to improve the performance of vertical GaN power devices necessary for high-voltage and high-frequency applications. For the development of GaN devices, nondestructive characterization of electrical properties particularly for carrier densities in the order of 10 19  cm −3 or higher is highly favorable. In this study, we investigated GaN single crystals with different carrier densities of up to 10 20  cm −3 using THz time-domain ellipsometry in reflection configuration. The p - and s -polarized THz waves reflected off the GaN samples are measured and then corrected based on the analysis of multiple waveforms measured with a rotating analyzer. We show that performing such analysis leads to a ten times higher precision than by merely measuring the polarization components. As a result, the carrier density and mobility parameters can be unambiguously determined even at high conductivities.

The pathogenesis of kidney stone formation includes multi-step processes involving complex interactions between mineral components and protein matrix. Calcium-binding proteins in kidney stones have great influences on the stone formation. The spatial distributions of these proteins in kidney stones are essential for evaluating the in vivo effects of proteins on the stone formation, although the actual distribution of these proteins is still unclear. We reveal micro-scale distributions of three different proteins, namely osteopontin (OPN), renal prothrombin fragment 1 (RPTF-1), and calgranulin A (Cal-A), in human kidney stones retaining original mineral phases and textures: calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD). OPN and RPTF-1 were distributed inside of both COM and COD crystals, whereas Cal-A was distributed outside of crystals. OPN and RPTF-1 showed homogeneous distributions in COM crystals with mosaic texture, and periodically distributions parallel to specific crystal faces in COD crystals. The unique distributions of these proteins enable us to interpret the different in vivo effects of each protein on CaOx crystal growth based on their physico-chemical properties and the complex physical environment changes of each protein. This method will further allow us to elucidate in vivo effects of different proteins on kidney stone formation.

In a male-based revision of ants of the subfamily Amblyoponinae from the Southwest Indian Ocean islands (SWIO: Comoros, Madagascar, Mauritius, Mayotte, Reunion, and Seychelles), we explore and reconsider male morphological characters that distinguish genera within the group. Our investigation redefines Amblyopone Erichson sensu Brown (1960), here referred to as Amblyopone sensu lato, into three genera: Xymmer Santschi stat. rev.,Amblyopone sensu stricto, Stigmatomma Roger stat. rev. All species names under Amblyopone s. l. reassign into Xymmer and Amblyopone s. s., which are small, well-defined genera, and Stigmatomma, a large group with a generic delimitation that still needs further refinement. Based on a study of male mandible characters and our scenario for mandibular evolution of the worker caste within Amblyopone s. l, we conclude that Amblyopone s. s. nests outside of XMAS (Xymmer+Mystrium+Adetomyrma+Stigmatomma) clade. The following names are transferred from Amblyopone s. l. to Xymmer as comb. rev.: muticus. The following names are transferred from Amblyopone s. l. to Stigmatomma as comb. rev.: amblyops, armigerum, bellii, bierigi, bruni, celata, chilense, denticulatum, elongatum, emeryi, feae, impressifrons, luzonicum, minuta, normandi, oregonense, pallipes, quadratum, reclinatum, rothneyi, santschii, saundersi, silvestrii, zwaluwenburgi; as comb. nov.: agostii, annae, besucheti, boltoni, caliginosum, cleae, crenatum, degeneratum, egregium, electrinum, eminia, exiguum, falcatum, ferrugineum, fulvidum, gaetulicum, gingivalis, glauerti, gnoma, gracile, groehni, heraldoi, lucidum, lurilabes, monrosi, mystriops, noonadan, octodentatum, ophthalmicum, orizabanum, papuanum, pertinax, pluto, punctulatum, rubiginoum, sakaii, smithi, trigonignathum, trilobum, wilsoni, zaojun, and testaceum. A male-based key to the genera of Malagasy amblyoponine ants, their diagnoses, and a discussion of the evolution of the morphological character of males in the subfamily are given, and the distinguishing characters of each are illustrated. In addition, our results predict that Paraprionopelta belongs in the XMAS clade and that Concoctio should have males with two mandibular teeth.

We sought to identify and quantitatively analyze calcium oxalate (CaOx) kidney stones on the order of micrometers, with a focus on the quantitative identification of calcium oxalate monohydrate (COM) and dihydrate (COD). We performed Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), and microfocus X-ray computed tomography measurements (microfocus X-ray CT) and compared their results. An extended analysis of the FTIR spectrum focusing on the 780 cm −1 peak made it possible to achieve a reliable analysis of the COM/COD ratio. We succeeded in the quantitative analysis of COM/COD in 50-μm 2 areas by applying microscopic FTIR for thin sections of kidney stones, and by applying microfocus X-ray CT system for bulk samples. The analysis results based on the PXRD measurements with micro-sampling, the microscopic FTIR analysis of thin sections, and the microfocus X-ray CT system observation of a bulk kidney stone sample showed roughly consistent results, indicating that all three methods can be used complementarily. This quantitative analysis method evaluates the detailed CaOx composition on the preserved stone surface and provides information on the stone formation processes. This information clarifies where and which crystal phase nucleates, how the crystals grow, and how the transition from the metastable phase to the stable phase proceeds. The phase transition affects the growth rate and hardness of kidney stones and thus provides crucial clues to the kidney stone formation process.

Early-stage control of invasive ants provides an opportunity to suppress establishment while conserving existing biodiversity. We developed and tested a selective control strategy targeting the Browsing ant Lepisiota frauenfeldi, an emerging omnivorous, polygynous, and polydomous invader, during its initial establishment in an urban area of Okinawa Island, Japan. Because the local ant community was still present when the invasion was detected, the trial aimed at reducing the competitive advantage of the target species while preserving biotic resistance from resident species. We hypothesized that weakening L. frauenfeldi through selective chemical treatment would allow existing species to occupy its vacant niches, thereby accelerating eradication. Species-specific baits were formulated using a growth regulator with protein- and carbohydrate-based substrates. Baits were placed near nest entrances identified through monthly surveys over an area of approximately 1.6 hectares. Ant community dynamics were monitored for 44 months using hand-collection and sticky-trap surveys. The invasive ant showed a strong negative response to treatment, with an estimated 92% reduction in occurrence probability, ultimately disappearing from the treated area. Several non-target ant species increased in frequency, consistent with expectation of the niche reoccupation, while most other species remained stable, indicating minimal impact on the broader community. Compared to conventional methods, this approach used drastically less chemical while achieving high efficacy. Implementation through cross-organizational collaboration enabled parallel treatment in adjacent restricted areas and contributed to the program's success. These results highlight the practical and ecological value of nest-targeted, community-collaborative selective baiting as a strategy for managing omnivorous invasive ants during early establishment.

Ecologists have many ways to measure and monitor ecosystems, each of which can reveal details about the processes unfolding therein. Acoustic recording combined with machine learning methods for species detection can provide remote, automated monitoring of species richness and relative abundance. Such recordings also open a window into how species behave and compete for niche space in the sensory environment. These opportunities are associated with new challenges: the volume and velocity of such data require new approaches to species identification and visualization. Here we introduce a newly-initiated acoustic monitoring network across the subtropical island of Okinawa, Japan, as part of the broader OKEON (Okinawa Environmental Observation Network) project. Our aim is to monitor the acoustic environment of Okinawa’s ecosystems and use these space–time data to better understand ecosystem dynamics. We present a pilot study based on recordings from five field sites conducted over a one-month period in the summer. Our results provide a proof of concept for automated species identification on Okinawa, and reveal patterns of biogenic vs. anthropogenic noise across the landscape. In particular, we found correlations between forest land cover and detection rates of two culturally important species in the island soundscape: the Okinawa Rail and Ruddy Kingfisher. Among the soundscape indices we examined, NDSI, Acoustic Diversity and the Bioacoustic Index showed both diurnal patterns and differences among sites. Our results highlight the potential utility of remote acoustic monitoring practices that, in combination with other methods can provide a holistic picture of biodiversity. We intend this project as an open resource, and wish to extend an invitation to researchers interested in scientific collaboration.

The dependence of pulse duration on crystal nucleation of urea induced by laser ablation of liquid was studied. The focused irradiation with laser pulses with all the duration conditions in this study (from 300 to 1200 fs) could induce the crystallization from the laser focus, which allowed for the systematic evaluation of probability of the laser-induced crystallization. We also carried out the microsecond-scale fast imaging of laser ablation of urea solutions to investigate the spatiotemporal dynamics of generation, expansion, collapse of cavitation bubbles induced by laser ablation, which can be one of the main triggers for crystal nucleation. As the result, we found that the laser-induced crystallization of urea is governed by the interplay of supersaturation increase by cavitation bubbles and supersaturation decrease by temperature rise. The findings provide the fundamental insight into the underlying mechanism of the laser-induced crystal nucleation and will also be useful for exploring optimized laser irradiation conditions for more efficient crystallization of organic materials in solutions.

Soft x-ray microscopy (SXM) is a minimally invasive technique for single-cell high-resolution imaging as well as the visualization of intracellular distributions of light elements such as carbon, nitrogen, and oxygen. We used SXM to observe photosynthesis and nitrogen fixation in the filamentous cyanobacterium Anabaena sp. PCC 7120, which can form heterocysts during nitrogen starvation. Statistical and spectroscopic analyses from SXM images around the K-absorption edge of nitrogen revealed a significant difference in the carbon-to-nitrogen (C/N) ratio between vegetative cells and heterocysts. Application of this analysis to soft x-ray images of Anabaena sp. PCC 7120 revealed inhomogenous C/N ratios in the cells. Furthermore, soft x-ray tomography of Anabaena sp. PCC 7120 revealed differing cellular C/N ratios, indicating different carbon and nitrogen distributions between vegetative cells and heterocysts in three dimensions.

Sea container has been identified as a major pathway for the unintended entry and spread of alien ant species. In Japan, red imported fire ants, Solenopsis invicta Buren (Hymenoptera: Formicidae), which are among the most harmful alien ants, were first detected in a shipping container from China in May 2017, and the invasion into Japan via the trade pathway is still continuing. To prevent containers contaminated with S. invicta and its establishment in Japan, control measures, such as repellents, are urgently required. The present study is the first to evaluate repellency of microencapsulated allyl isothiocyanate (AITC) against S. invicta, as a preliminary step to use the innovative equipment for invasive species management in sea containers. In a field in Taiwan heavily infested with S. invicta, a repellent test of microencapsulated AITC using bait traps showed that the equipment completely prevents S. invicta from accessing the bait. Due to its volatility and irritancy, AITC, a safe natural repellant in wasabi (Eutrema japonicum (Miq.) Kiudz), has not been used for pest management in containerized cargo. However, the encapsulation of AITC solves this problem by allowing controlled vapor release. Microencapsulated AITC has considerable potential as an effective measure to stop the spread of S. invicta through global trade.

The protein crystal growth mechanism can be changed from planar 2D nucleation growth to spiral growth by femtosecond laser ablation. By using this method, the growth rate of a hen egg-white lysozyme crystal increases from 0.3 µm per day to 3.4 µm per day. Large single crystals with desirable shapes are essential for various scientific and industrial fields, such as X-ray/neutron crystallography and crystalline devices. However, in the case of proteins the production of such crystals is particularly challenging, despite the efforts devoted to optimization of the environmental, chemical and physical parameters. Here we report an innovative approach for promoting the growth of protein crystals by directly modifying the local crystal structure via femtosecond laser ablation. We demonstrate that protein crystals with surfaces that are locally etched (several micrometers in diameter) by femtosecond laser ablation show enhanced growth rates without losing crystal quality. Optical phase-sensitive microscopy and X-ray topography imaging techniques reveal that the local etching induces spiral growth, which is energetically advantageous compared with the spontaneous two-dimensional nucleation growth mode. These findings prove that femtosecond laser ablation can actively switch the crystal growth mode, offering flexible control over the size and shape of protein crystals.