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The magnetism of a narrow (~1.6 nm) grain boundary phase produced in a 0.1 at% Ga-doped Nd–Fe–B sintered magnet was examined using electron holography. The magnetic flux density was determined to be 0.8 ± 0.1 T, which was smaller than that for a commercial magnet free from Ga doping (~1.0 T). The presence of a ferromagnetic grain boundary phase reasonably explained the functionality of the 0.1 at% Ga-doped system, such as the improvement in the squareness of the demagnetization curve. The observations provide useful information for deeper understanding of the coercivity mechanism in Ga-doped Nd–Fe–B sintered magnets.

Obesity is a risk factor for asthma, especially nonatopic asthma, and attenuates the efficacy of standard asthma therapeutics. Obesity also augments pulmonary responses to ozone, a nonatopic asthma trigger. The purpose of this study was to determine whether obesity-related alterations in gut microbiota contribute to these augmented responses to ozone. Ozone-induced increases in airway responsiveness, a canonical feature of asthma, were greater in obese db/db mice than in lean wild-type control mice. Depletion of gut microbiota with a cocktail of antibiotics attenuated obesity-related increases in the response to ozone, indicating a role for microbiota. Moreover, ozone-induced airway hyperresponsiveness was greater in germ-free mice that had been reconstituted with colonic contents of db/db than in wild-type mice. In addition, compared with dietary supplementation with the nonfermentable fiber cellulose, dietary supplementation with the fermentable fiber pectin attenuated obesity-related increases in the pulmonary response to ozone, likely by reducing ozone-induced release of IL-17A. Our data indicate a role for microbiota in obesity-related increases in the response to an asthma trigger and suggest that microbiome-based therapies such as prebiotics may provide an alternative therapeutic strategy for obese patients with asthma.

We have previously reported that the mouse gut microbiome contributes to pulmonary responses to ozone, a common asthma trigger, and that short-chain fatty acids, end products of bacterial fermentation, likely contribute to this role of the microbiome. A growing body of evidence indicates that there are sex-related differences in gut microbiota and these differences can have important functional consequences. The purpose of this study was to determine whether there are sex-related differences in the impact of the gut microbiota on pulmonary responses to ozone. After acute exposure to ozone, male mice developed greater airway hyperresponsiveness than female mice. This difference was abolished after antibiotic ablation of the gut microbiome. Moreover, weanling female pups housed in cages conditioned by adult male mice developed greater ozone-induced airway hyperresponsiveness than weanling female pups raised in cages conditioned by adult females. Finally, ad libitum oral administration via drinking water of the short-chain fatty acid propionate resulted in augmented ozone-induced airway hyperresponsiveness in male, but not female, mice. Overall, these data are consistent with the hypothesis that the microbiome contributes to sex differences in ozone-induced airway hyperresponsiveness, likely as a result of sex differences in the response to short-chain fatty acids.

This review examines methods of magnetic flux density measurements from the narrow grain boundary (GB) regions, the thickness of which is of the order of nanometers, produced in Nd–Fe–B-based sintered magnets. Despite of the complex crystallographic microstructure and the significant stray magnetic field of the sintered magnet, recent progress in electron holography allowed for the determination of the intrinsic magnetic flux density due to the GB which is embedded in the polycrystalline thin-foil. The methods appear to be useful as well for intensive studies about interface magnetism in a variety of systems.

Ozone causes airway hyperresponsiveness, a defining feature of asthma. We have reported that the gut microbiome contributes to sex differences in ozone-induced airway hyperresponsiveness. Altering dietary fiber affects the gut microbiome. The purpose of this study was to determine the effects of dietary fiber on pulmonary responses to ozone and whether these effects differ by sex. We fed male and female mice fiber-free diets or diets enriched in one of two types of dietary fiber, cellulose and pectin, for 3 days before ozone exposure. Compared with control diets or pectin-enriched diets, cellulose-enriched diets attenuated ozone-induced airway hyperresponsiveness in male but not female mice. In contrast, fiber-free diets augmented responses to ozone in female but not male mice. Analysis of 16S rRNA sequencing of fecal DNA also indicated sex differences in the impact of dietary fiber on the gut microbiome and identified bacterial taxa that were associated with ozone-induced airway hyperresponsiveness. Our data suggest that microbiome-based therapies such as prebiotics may provide an alternative therapeutic strategy for air pollution-triggered asthma, but they indicate that such therapeutics may need to be tailored differently for males and females.

The magnetism of grain boundary (GB) phases in the Nd-rich Ga-doped Nd-Fe-B sintered magnet that shows unusually high improvement in coercivity by post-sinter optimal heat treatment was studied using electron holography. Transmission electron microscopy observations identified three types of GB phases with distinct structures, i.e., Ia 3 ¯ -type, amorphous-type, and Nd6(Fe,Ga)14-type. The magnetic flux densities of these three GB phases were systematically analyzed by measuring the phase shifts of incident electrons, and all of these GB phases are concluded to be nonferromagnetic. Unlike the standard commercial sintered magnets, this study has shown that the Nd2Fe14B grains in the optimally heat treated Nd-rich Ga-doped sintered magnet are exchange decoupled by the formation of the three types of nonferromagnetic GB phases. The observations provide useful information for GB engineering of Nd-Fe-B sintered magnets, which is key for further improvements of their coercivities without relying on grain size refinement.

The basic morphology of phase-separated VO 2 films, in which the tetragonal (metallic) phase coexists with the monoclinic (insulating) phase, was studied using transmission electron microscopy. While the phase transformation temperature in an unstrained crystal is approximately 340 K, it was observed that at 298 K, elastic strain (caused by lattice mismatch with the TiO 2 -(001) substrate) stabilized the tetragonal phase near the VO 2 /TiO 2 boundary. The observed zig-zag-shaped interface of the tetragonal phase was explained by the crystallographic orientation relationship between the tetragonal and monoclinic phases. The observations provide valuable information for future applications of VO 2 films.

This study examined the growth of GaN layers by molecular beam epitaxy (MBE) using a tungsten carbide (WC) buffer sputtered on a Si(111) surface. The chemical stability of the WC layer against the Ga-Si interaction was verified experimentally. A low-temperature (LT) buffer is essential for the growth of single-crystal-quality, high-temperature gallium nitride (HT-GaN) on a WC surface. In addition, dislocation termination techniques, such as interface formation and the annealing of the buffer layer, were adopted to improve the crystalline quality. The HT-GaN sample grown on the annealed double-buffer-layer (AlN/GaN) revealed an X-ray diffraction full-width at half maximum, Hall carrier density, and carrier mobility of 2260 arcsecs, 4.39 × 1018 cm3, and 19.4 cm2/Vs, respectively. The crystalline quality of the GaN layer is discussed in comparison with previously reported GaN/sapphire samples.

The microstructure in a Mn 55.2 Ga 19.0 Cu 25.8 alloy that exhibits both martensitic and diffusional phase transformations was examined by electron microscopy, and the potential effects of these transformations on the large coercivity (~ 2 T) were discussed. The alloy showed a cellular microstructure, composed of a cuboidal matrix enveloped by a boundary phase, and superposed on well-defined martensite plates. Since the boundary phase is enriched by the non-magnetic element Cu, it may serve as magnetic isolation for the matrix region with a face centered tetragonal lattice formed by the martensitic transformation, or offer potential pinning sites for magnetic domain walls.

Background: Ozone increases IL-33 in the lungs, and obesity augments the pulmonary effects of acute ozone exposure. Objectives: We assessed the role of IL-33 in the augmented effects of ozone observed in obese mice. Methods: Lean wildtype and obese db/db mice were pretreated with antibodies blocking the IL-33 receptor, ST2, and then exposed to ozone (2 ppm for 3 hr). Airway responsiveness was assessed, bronchoalveolar lavage (BAL) was performed, and lung cells harvested for flow cytometry 24 hr later. Effects of ozone were also assessed in obese and lean mice deficient in γδ T cells and their wildtype controls. Results and Discussion: Ozone caused greater increases in BAL IL-33, neutrophils, and airway responsiveness in obese than lean mice. Anti-ST2 reduced ozone-induced airway hyperresponsiveness and inflammation in obese mice but had no effect in lean mice. Obesity also augmented ozone-induced increases in BAL CXCL1 and IL-6, and in BAL type 2 cytokines, whereas anti-ST2 treatment reduced these cytokines. In obese mice, ozone increased lung IL-13+ innate lymphoid cells type 2 (ILC2) and IL-13+ γδ T cells. Ozone increased ST2+ γδ T cells, indicating that these cells can be targets of IL-33, and γδ T cell deficiency reduced obesity-related increases in the response to ozone, including increases in type 2 cytokines. Conclusions: Our data indicate that IL-33 contributes to augmented responses to ozone in obese mice. Obesity and ozone also interacted to promote type 2 cytokine production in γδ T cells and ILC2 in the lungs, which may contribute to the observed effects of IL-33. Citation: Mathews JA, Krishnamoorthy N, Kasahara DI, Cho Y, Wurmbrand AP, Ribeiro L, Smith D, Umetsu D, Levy BD, Shore SA. 2017. IL-33 drives augmented responses to ozone in obese mice. Environ Health Perspect 125:246–253; http://dx.doi.org/10.1289/EHP272

Background Interleukin-33 is released in the airways following acute ozone exposure and has the ability to cause airway hyperresponsiveness, a defining feature of asthma. Ozone causes greater airway hyperresponsiveness in male than female mice. Moreover, sex differences in the gut microbiome account for sex differences in this response to ozone. The purpose of this study was to determine whether there were sex differences in the role of interleukin-33 in ozone-induced airway hyperresponsiveness and to examine the role of the microbiome in these events. Methods Wildtype mice and mice genetically deficient in ST2, the interleukin-33 receptor, were housed from weaning with either other mice of the same genotype and sex, or with mice of the same sex but opposite genotype. At 15 weeks of age, fecal pellets were harvested for 16S rRNA sequencing and the mice were then exposed to air or ozone. Airway responsiveness was measured and a bronchoalveolar lavage was performed 24 h after exposure. Results In same-housed mice, ozone-induced airway hyperresponsiveness was greater in male than female wildtype mice. ST2 deficiency reduced ozone-induced airway hyperresponsiveness in male but not female mice and abolished sex differences in the response to ozone. However, sex differences in the role of interleukin-33 were unrelated to type 2 cytokine release: ozone-induced increases in bronchoalveolar lavage interleukin-5 were greater in females than males and ST2 deficiency virtually abolished interleukin-5 in both sexes. Since gut microbiota contribute to sex differences in ozone-induced airway hyperresponsiveness, we examined the role of the microbiome in these ST2-dependent sex differences. To do so, we cohoused wildtype and ST2 deficient mice, a situation that allows for transfer of microbiota among cage-mates. Cohousing altered the gut microbial community structure, as indicated by 16S rRNA gene sequencing of fecal DNA and reversed the effect of ST2 deficiency on pulmonary responses to ozone in male mice. Conclusions The data indicate that the interleukin-33 /ST2 pathway contributes to ozone-induced airway hyperresponsiveness in male mice and suggest that the role of interleukin-33 is mediated at the level of the gut microbiome. Electronic supplementary material The online version of this article (10.1186/s12931-019-1168-x) contains supplementary material, which is available to authorized users.

Ozone is an asthma trigger. In mice, the gut microbiome contributes to ozone-induced airway hyperresponsiveness, a defining feature of asthma, but the mechanistic basis for the role of the gut microbiome has not been established. Gut bacteria can affect the function of distal organs by generating metabolites that enter the blood and circulate systemically. We hypothesized that global metabolomic profiling of serum collected from ozone exposed mice could be used to identify metabolites contributing to the role of the microbiome in ozone-induced airway hyperresponsiveness. Mice were treated for two weeks with a cocktail of antibiotics (ampicillin, neomycin, metronidazole, and vancomycin) in the drinking water or with control water and then exposed to air or ozone (2 ppm for 3 hours). Twenty four hours later, blood was harvested and serum analyzed via liquid-chromatography or gas-chromatography coupled to mass spectrometry. Antibiotic treatment significantly affected 228 of the 562 biochemicals identified, including reductions in the known bacterially-derived metabolites, equol, indole propionate, 3-indoxyl sulfate, and 3-(4-hydroxyphenyl)propionate, confirming the efficacy of the antibiotic treatment. Ozone exposure caused significant changes in 334 metabolites. Importantly, ozone-induced changes in many of these metabolites were different in control and antibiotic-treated mice. For example, most medium and long chain fatty acids declined by 20–50% with ozone exposure in antibiotic-treated but not control mice. Most taurine-conjugated bile acids increased with ozone exposure in antibiotic-treated but not control mice. Ozone also caused marked (9-fold and 5-fold) increases in the polyamines, spermine and spermidine, respectively, in control but not antibiotic-treated mice. Each of these metabolites has the capacity to alter airway responsiveness and may account for the role of the microbiome in pulmonary responses to ozone.

【The microstructural properties and electrical characteristics of sputtering films deposited with a Cu-Ga target are analyzed. The Cu-Ga target is prepared using the cold spray process and shows generally uniform composition distributions, as suggested by secondary ion mass spectrometer (SIMS) data. Characteristics of the sputtered Cu-Ga films are investigated at three positions (top, center and bottom) of the Cu-Ga target by X-ray diffraction (XRD), SIMS, 4-point probe and transmission electron microscopy (TEM) analysis methods. The results show that the Cu-Ga films are composed of hexagonal and unknown phases, and they have similar distributions of composition and resistivity at the top, center, and bottom regions of the Cu-Ga target. It demonstrates that these films have uniform properties regardless of the position on the Cu-Ga target. In conclusion, the cold spray process is expected to be a useful method for preparing sputter targets.】

Previous reports demonstrate that the microbiome impacts allergic airway responses, including airway hyperresponsiveness, a characteristic feature of asthma. Here we examined the role of the microbiome in pulmonary responses to a nonallergic asthma trigger, ozone. We depleted the microbiota of conventional mice with either a single antibiotic (ampicillin, metronidazole, neomycin, or vancomycin) or a cocktail of all four antibiotics given via the drinking water. Mice were then exposed to room air or ozone. In air-exposed mice, airway responsiveness did not differ between antibiotic- and control water-treated mice. Ozone caused airway hyperresponsiveness, the magnitude of which was decreased in antibiotic cocktail-treated mice versus water-treated mice. Except for neomycin, single antibiotics had effects similar to those observed with the cocktail. Compared with conventional mice, germ-free mice also had attenuated airway responsiveness after ozone. 16S ribosomal RNA gene sequencing of fecal DNA to characterize the gut microbiome indicated that bacterial genera that were decreased in mice with reduced ozone-induced airway hyperresponsiveness after antibiotic treatment were short-chain fatty acid producers. Serum analysis indicated reduced concentrations of the short-chain fatty acid propionate in cocktail-treated mice but not in neomycin-treated mice. Dietary enrichment with pectin, which increased serum short-chain fatty acids, also augmented ozone-induced airway hyperresponsiveness. Furthermore, propionate supplementation of the drinking water augmented ozone-induced airway hyperresponsiveness in conventional mice. Our data indicate that the microbiome contributes to ozone-induced airway hyperresponsiveness, likely via its ability to produce short-chain fatty acids.

Ozone causes airway hyperresponsiveness (AHR) and pulmonary inflammation. Rho kinase (ROCK) is a key regulator of smooth muscle cell contraction and inflammatory cell migration. To determine the contribution of the two ROCK isoforms ROCK1 and ROCK2 to ozone-induced AHR, we exposed wild-type, ROCK1+/−, and ROCK2+/− mice to air or ozone (2 ppm for 3 h) and evaluated mice 24 h later. ROCK1 or ROCK2 haploinsufficiency did not affect airway responsiveness in air-exposed mice but significantly reduced ozone-induced AHR, with a greater reduction in ROCK2+/− mice despite increased bronchoalveolar lavage (BAL) inflammatory cells in ROCK2+/− mice. Compared with wild-type mice, ozone-induced increases in BAL hyaluronan, a matrix protein implicated in ozone-induced AHR, were lower in ROCK1+/− but not ROCK2+/− mice. Ozone-induced increases in other inflammatory moieties reported to contribute to ozone-induced AHR (IL-17A, osteopontin, TNFα) were not different in wild-type vs. ROCK1+/− or ROCK2+/− mice. We also observed a dose-dependent reduction in ozone-induced AHR after treatment with the ROCK1/ROCK2 inhibitor fasudil, even though fasudil was administered after induction of inflammation. Ozone increased pulmonary expression of ROCK2 but not ROCK1 or RhoA. A ROCK2 inhibitor, SR3677, reduced contractile forces in primary human airway smooth muscle cells, confirming a role for ROCK2 in airway smooth muscle contraction. Our results demonstrate that ozone-induced AHR requires ROCK. Whereas ROCK1-dependent changes in hyaluronan may contribute to ROCK1's role in O3-induced AHR, the role of ROCK2 is downstream of inflammation, likely at the level of airway smooth muscle contraction.

A quantitative analysis of In concentration in InGaN/GaN multiquantum wells in light-emitting diodes was carried out using high-resolution transmission electron microscopy (HRTEM) and high-angle annual dark-field scanning TEM (HAADF-STEM). The In composition in InGaN was evaluated by the precise measurement of c-lattice parameters in the HRTEM micrographs, which increase with increasing In composition. The reliability of the results was confirmed by high-resolution x-ray diffraction measurements and Rutherford backscattering spectrometry. Quantitative In compositions can, therefore, be determined using HRTEM. We tried to determine the quantitative In compositions in InGaN by analyzing the intensity profiles of the HAADF-STEM images. However, several problems were encountered, such as differences in the thickness of the region observed, carbon contamination, and ion beam damage during specimen preparation. Therefore, relative differences in composition were observed in the HAADF-STEM images.

Remarkable reduction of the threading dislocation (TD) density has been achieved by inserting a GaN layer grown at an intermediate temperature (900 °C) (IT-GaN layer), just prior to the growth of GaN at 1040 °C by using a hydride vapor phase epitaxy. The variation in the dislocation density variation along the growth direction was observed by using cathodoluminescence (CL) and transmission electron microscopy (TEM). A cross-sectional CL image revealed that the reduction of the TD density happened during the growth of IT-GaN layer. The TEM measurement provided the proof that the TD reduction could be ascribed to the masking of the TD by stacking faults in the IT-GaN layer.

Graphene is a monolayer of carbon atoms arranged in a honeycomb lattice and is a basic building block for graphitic materials of all other dimensionalities. It can be wrapped up into zero-dimensional fullerenes, rolled into one-dimensional nanotubes or stacked into three-dimensional graphite. Graphene has unusual electrical, mechanical, and thermal properties, so it presents new opportunities in fundamental research and practical applications (Zhang et al., 2005; Geim & Novoselov, 2007; Geim, 2009). Recently, large-area synthesis methods for graphene have been advanced epitaxial growth on SiC (Brar et al., 2007; Qi et al., 2010) and chemical vapor deposition on metal substrates such as Ni (Dedkov et al., 2008) and Cu (Li et al., 2009). Particularly, Cu is a considerably attractive substrate because it can be produce layer-area graphene. Transmission electron microscopy (TEM) is a direct and re latively fast imaging tool ideally suited for suspended atomically thin membranes, so it has been successfully applied to study adsorbates on graphene and the atomic structure of graphene (Huang et al., 2011). To observe graphene by TEM, the graphene must transfer from metallic Cu substrates to a TEM grid. Standard transfer of layer graphene has been carried out using a polymer coating such as polymethyl methacrylate (PMMA) or polydimethylsiloxane as a temporary support during etching of the metal substrate to prevent tearing of the graphene (Reina et al., 2009). However, the standard transfer method using these polymers can contaminate and mechanically damage the graphene because it includes several wet chemical steps. Thus, a simple and gentle method is necessary for good TEM images of graphene. Direct transfer method doesn’t include polymer coating process. So it is expected simple and effective method to make graphene specimen by avoiding wet chemical steps (Regan, 2010).

Ozone and obesity both increase IL-17A in the lungs. In mice, obesity augments the airway hyperresponsiveness and neutrophil recruitment induced by acute ozone exposure. Therefore, we examined the role of IL-17A in obesity-related increases in the response to ozone observed in obese mice. Lean wild-type and obese db/db mice were pretreated with IL-17A–blocking or isotype antibodies, exposed to air or ozone (2 ppm for 3 h), and evaluated 24 hours later. Microarray analysis of lung tissue gene expression was used to examine the mechanistic basis for effects of anti–IL-17A. Compared with lean mice, ozone-exposed obese mice had greater concentrations of BAL IL-17A and greater numbers of pulmonary IL-17A(+) cells. Ozone-induced increases in BAL IL-23 and CCL20, cytokines important for IL-17A(+) cell recruitment and activation, were also greater in obese mice. Anti–IL-17A treatment reduced ozone-induced airway hyperresponsiveness toward levels observed in lean mice. Anti–IL-17A treatment also reduced BAL neutrophils in both lean and obese mice, possibly because of reductions in CXCL1. Microarray analysis identified gastrin-releasing peptide (GRP) receptor (Grpr) among those genes that were both elevated in the lungs of obese mice after ozone exposure and reduced after anti–IL-17A treatment. Furthermore, ozone exposure increased BAL GRP to a greater extent in obese than in lean mice, and GRP-neutralizing antibody treatment reduced obesity-related increases in ozone-induced airway hyperresponsiveness and neutrophil recruitment. Our data indicate that IL-17A contributes to augmented responses to ozone in db/db mice. Furthermore, IL-17A appears to act at least in part by inducing expression of Grpr.

Pulmonary responses to the air pollutant, ozone, are increased in obesity. Both obesity and ozone cause changes in systemic metabolism. Consequently, we examined the impact of ozone on the lung metabolomes of obese and lean mice. Lean wildtype and obese db/db mice were exposed to acute ozone (2 ppm for 3 h) or air. 24 hours later, the lungs were excised, flushed with PBS to remove blood and analyzed via liquid-chromatography or gas-chromatography coupled to mass spectrometry for metabolites. Both obesity and ozone caused changes in the lung metabolome. Of 321 compounds identified, 101 were significantly impacted by obesity in air-exposed mice. These included biochemicals related to carbohydrate and lipid metabolism, which were each increased in lungs of obese versus lean mice. These metabolite changes may be of functional importance given the signaling capacity of these moieties. Ozone differentially affected the lung metabolome in obese versus lean mice. For example, almost all phosphocholine-containing lysolipids were significantly reduced in lean mice, but this effect was attenuated in obese mice. Glutathione metabolism was also differentially affected by ozone in obese and lean mice. Finally, the lung metabolome indicated a role for the microbiome in the effects of both obesity and ozone: all measured bacterial/mammalian co-metabolites were significantly affected by obesity and/or ozone. Thus, metabolic derangements in obesity appear to impact the response to ozone.

Structural defects present on chemical vapor deposition (CVD)-graphene have usually originated from the growth stage and transfer process. They limit the electronic transport properties of graphene and degrade performance of related devices. Here we report that these inherent atomic defects could be selectively healed by a simple vapor phase treatment performed in equipment conventionally used for atomic layer deposition (ALD). The unique chemistry of Al2O3 ALD facilitated selective depositions of AlxOy compounds on the defects, which could be readily probed and visualized using AFM imaging. The healing agent, AlxOy, was observed to bind tightly to the defects and lead to doping of the CVD-graphene, which was reflected in the noticeable improvement in electrical sheet resistance. In contrast with the chemically doped graphene, the ALD-treated graphenes revealed notable long-term stability under environmental conditions. Our approach promises selective healing of defects present in most materials and possibly ensures considerable improvement in electrical and mechanical properties. ALD with a broad spectrum of material selection could be a versatile tool for upgrading properties of materials.

Thick GaN film was grown by hydride vapor phase epitaxy (HVPE) on spinel covered ZnO layer. Single crystal ZnO was grown on c -plane sapphire by ultra high vacuum (UHV) DC sputtering. A thin Al layer was thermally deposited on it. A spinel layer was formed by a solid phase reaction of the Al and ZnO layers, and GaN thick film was grown on it. Structural and chemical properties of the spinel layer were studied by X-ray diffraction (XRD) and secondary ion mass spectroscopy (SIMS), respectively. The crystal quality of GaN was observed by atomic force microscope (AFM) and transmission electron microscope (TEM). We found that the spinel layer is helpful for the reduction of zinc and oxygen diffusion into GaN during the HVPE growth.

Aluminum oxynitride (AlON), which is conventionally used as one of the ceramics with good thermal and chemical stability, has an attractive candidate for a tunable extreme UV luminous material due to its unique combination of properties and UV luminescence. In this paper, we have synthesized the novel AlON UV emitting materials, which have a wavelength from 4.29 to 4.54 eV, and discovered the core (AlON)-shell (Al2O3) like structures in a transmission electron microscopy. Furthermore, their potential application in a UV light emitter has been demonstrated by applying the combination with a CNT field emission cold cathode, which has been made by a simple printing method. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We proposed an indium-tin-oxide (ITO) based gas sensor which can operate at room temperature. ITO nano-crystal was screen printed on a quartz substrate. To improve the sensitivity and to decrease the resistivity of the printed ITO layer, pressurized annealing was adopted. Resistivity of the printed ITO gas sensor decreased from 3.5 kΩcm to 1.56 Ωcm by pressurized annealing. We could observe room temperature operation of the printed ITO gas sensor by using various gases such as Ar, N2, O2 and CH4. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Recent years have seen a great deal of progress in the development of transmission electron microscopy-based techniques for strain measurement. Dark-field electron holography (DFEH) is a new technique offering configuration of the off-axis principle. Using this technique with medium magnification (Holo-M), we carried out strain measurements in nanoscale-triangular SiGe/(001) Si with (004), (2-20) and (-111) diffraction spots. The reconstruction of holograms and interpretation of strain maps in term of strain precision were discussed and the strain distributions in the SiGe/(001) Si patterns were visualized. Based on linear anisotropic elastic theory for strain simulation, the simulated results obtained by the finite element method compared with the experimental results acquired by DFEH. The strain values were found to be 0.9-1.0%, 1.1-1.2% and 1.0-1.1%, for the (004), (2-20) and (-111) diffracted beams, respectively, and the strain precisions were determined to be ~2.1 × 10-3, 3.2 × 10-3 and 9.1 × 10-3 for the corresponding diffraction spots. As a result, DFEH is highlighted as a powerful technique for strain measurement, offering high-strain precision, high-spatial resolution and a large field of view.

Understanding the underlying mechanisms involved in graphene growth via chemical vapour deposition (CVD) is critical for precise control of the characteristics of graphene. Despite much effort, the actual processes behind graphene synthesis still remain to be elucidated in a large number of aspects. Herein, we report the evolution of graphene properties during in-plane growth of graphene from reduced graphene oxide (RGO) on copper (Cu) via methane CVD. While graphene is laterally grown from RGO flakes on Cu foils up to a few hundred nanometres during CVD process, it shows appreciable improvement in structural quality. The monotonous enhancement of the structural quality of the graphene with increasing length of the graphene growth from RGO suggests that seeded CVD growth of graphene from RGO on Cu surface is accompanied by the restoration of graphitic structure. The finding provides insight into graphene growth and defect reconstruction useful for the production of tailored carbon nanostructures with required properties.

Department of Nano-semiconductor Engineering, National Korea Maritime University, Busan 606-791, Korea*Department of Offshore Plant Management, National Korea Maritime University, Busan 606-791, Korea**Division of Electrical and Electronics Engineering, National Korea Maritime University, Busan 606-791, Korea***PAN-Xal Co., Ltd., Suwon 443-380, Korea****Center for Interdisciplinary Research, Tohoku University, Sendai 980-8577, Japan

Herein is a discussion of how the structural and optical properties of m-plane GaN (m-GaN) films are affected by the inclination direction of vicinal m-plane sapphire substrate. The m-GaN films were grown on three different types of substrates inclined toward the a-axis direction, the c-axis direction, and with no inclination. We found that m-GaN film grown on an m-plane sapphire inclined in the a-axis direction showed the highest quality with a smooth surface and a low stacking fault density. A model is proposed that shows how the surface step of a substrate can reduce the generation of stacking fault in m-GaN film.

We studied a kinetic model of the ZnO nanorod (NR) growth that occurs via vapor phase transportation (VPT). The mechanism of ZnO NR growth was discussed in terms of the length-to-diameter (L–D) relationship of NRs, and it was confirmed by varying both the type of catalyst and source material used. Both theoretical calculations and experimental data indicated that elongation of NRs is primarily determined by diffusion of the absorbed atoms (adatoms) within a nominal migration length on the surface, which is not considered in the simple vapor–liquid–solid model.

The present study focused on the effect of an intermediate-temperature (IT; ∼900 °C) buffer layer on GaN films, grown on an AlN/sapphire template by hydride vapor phase epitaxy (HVPE). In this paper, the surface morphology, structural quality, residual strain, and luminescence properties are discussed in terms of the effect of the buffer layer. The GaN film with an IT-buffer revealed a relatively lower screw-dislocation density (3.29×107 cm−2) and a higher edge-dislocation density (8.157×109 cm−2) than the GaN film without an IT-buffer. Moreover, the IT-buffer reduced the residual strain and improved the luminescence. We found that the IT-buffer played an important role in the reduction of residual strain and screw-dislocation density in the overgrown layer through the generation of edge-type dislocations and the spontaneous treatment of the threading dislocation by interrupting the growth and increasing the temperature.

Ga-doped zinc oxide (ZnO) (ZnO:Ga) nanocrystals were synthesized by the vapor-solidification method to investigate morphological and structural evolution induced by Ga-incorporation. Ga-content was controlled in the full composition range (0–100%). As the Ga-content increased, the shape of nanocrystals changed from tetrapod- to rod-type. Hard X-ray photoemission spectroscopy (HXPES) measurement indicates that highly Ga-doped uniphase ZnO:Ga nanocrystals without a serious deterioration of morphology are achieved, which strongly suggests the feasibility of Ga as a successful n-type dopant for ZnO-based nanocrystals.

Unusual growth-rate variation during GaN formation using gas-source MBE has been discussed with respect to the chemical reactions occurring in the transition layer. A series of samples were prepared to confirm the assumption by verifying the growth regime and the impacts on the crystal quality of the GaN film. We found that the growth rate can be varied along with the amount of NH3 supply even under NH3-rich condition with a fixed Ga flux. Two growth conditions were investigated for their impact on the transition layer. One was the atomic force microscopy result, which revealed that the adatom migration length is closely related to the transition layer formation. The other one is the photoluminescent spectra, which revealed that the luminescence property of GaN is strongly related to the transition layer.

A UV sensor was fabricated by screen printing indium–tin-oxide (ITO) nanocrystals on to quart glass. The initial printed ITO layer showed a resistivity too high for sensing applications, but considerable improvements were achieved through annealing under external pressure. The effects of this pressurized annealing were investigated using a commercial ITO film. The annealing aided the development of low-resistivity ITO through the repression of complex defects. The feasibility of the ITO sensor was confirmed through annealing coil-shaped ITO sensors under different conditions. Pressurized annealing greatly enhanced the output signal intensity under similar UV illumination conditions.

Table S1. BAL cytokine and chemokine concentrations measured 24â h after ozone exposure. Figure S1. BAL IL-33 in male and female mice. (DOCX 48 kb)