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The human epidermis is formed by the proliferation and differentiation of keratinocytes adjacent to the basement membrane. The outermost layer, the stratum corneum, is equipped with a barrier function that prevents water evaporation, and intercellular lipids play an important role in this barrier function. When the barrier is functioning normally, evaporation is prevented; however, when barrier function is impaired, moisture evaporates, resulting in dry and rough skin. Therefore, maintenance of normal barrier function is critical for maintaining normal skin function. Peroxisome proliferator-activated receptor α (PPARα) is mainly not only involved in lipid metabolism in the liver but is also expressed in the epidermis and is involved in inducing keratinocyte differentiation, promoting lipid production, maintaining barrier function and suppressing skin inflammation. Hence, compounds that activate PPARα are expected to control skin function. Therefore, we identified PPARα activators from among extracts of natural resources that have been approved for use in humans and analysed the effects of these extracts on skin function.First, extracts of 474 natural resources were screened using a PPARα activator screening cell line independently constructed in our laboratory. Next, reporter assays were performed using the Gal4-chimera system to evaluate whether these extracts act as ligands for PPARα. We then analysed their effect on primary normal human epidermal keratinocyte cells by using real-time RT-PCR. Finally, we evaluated PPARα activation effect by the combination of these extracts.We identified 36 extracts having the effect of activating PPARα. In particular, #419, a Typha angustifolia spike extract, showed concentration-dependent transcriptional activation through PPARα-LBD and was considered to be likely to contain a compound that is a ligand of PPARα. #419 increased the expression of PPARα target genes and genes related to skin function in primary cultured human epidermal keratinocytes. Finally, the use of #419 in combination with nine extracts increased PPAR activity more than twice as much as #419 alone treatment.These results showed that the reporter cell line could be useful for discovering extracts of natural resources and that the identified Typha angustifolia spike extract could be used in cosmetics that activate PPARα, which expected to improve skin function.L’épiderme humain se forme grâce à la prolifération et à la différenciation des kératinocytes adjacents à la membrane basale. La couche externe, dite « couche cornée », possède une fonction barrière qui empêche l’évaporation de l’eau, dans laquelle les lipides intercellulaires jouent un rôle important. Lorsque la barrière fonctionne normalement, l’évaporation est évitée ; mais lorsqu’elle est altérée, l’évaporation a lieu et la peau, privée d’hydratation, devient sèche et rêche. Par conséquent, il est capital de maintenir cette fonction barrière normale pour que la peau conserve son fonctionnement normal. Le récepteur alpha activé par proliférateurs de peroxysomes (PPARα) intervient surtout non seulement dans le métabolisme lipidique du foie, mais également dans l’épiderme ; il joue en effet un rôle dans l’induction de la différenciation des kératinocytes, la promotion de la production lipidique, le maintien de la fonction barrière et la suppression de l’inflammation de l’épiderme. Par conséquent, les activateurs du PPAR-α devraient être déterminants pour une bonne fonction cutanée. Nous avons donc identifié des activateurs du PPAR-α parmi des extraits de ressources naturelles dont l’utilisation chez l’homme est approuvée, et nous avons analysé les effets de ces extraits sur la fonction cutanée. MÉTHODES: Tout d’abord, des extraits de 474 ressources naturelles ont été sélectionnés à l’aide d’une lignée cellulaire de détection des activateurs du PPAR-α, construite indépendamment dans notre laboratoire. Ensuite, des tests de gènes rapporteurs ont été effectués à l’aide du système Gal4-chimera pour voir si ces extraits jouaient le rôle de ligands pour le PPAR-α. Nous avons ensuite analysé leur effet sur les cellules kératinocytaires épidermiques humaines normales primaires par RT-PCR en temps réel. Enfin, nous avons évalué l’effet d’activation du PPAR-α par l’association de ces extraits. RÉSULTATS: Nous avons identifié 36 extraits ayant pour effet d’activer le PPAR-α. En particulier, le n° 419, un extrait d’épi de Typha angustifolia, a montré une activation transcriptionnelle dépendante de la concentration par le PPAR-α-LBD et a été considéré comme susceptible de contenir un composé qui est un ligand du PPAR-α. Le n° 419 a augmenté l’expression des gènes cibles du PPAR-α et des gènes liés au fonctionnement de la peau dans les kératinocytes épidermiques humains primaires mis en culture. Enfin, l’utilisation du n° 419 en association avec neuf extraits a augmenté de plus du double l’activité du PPAR par rapport au traitement par le n° 419 seul.Ces résultats ont montré que la lignée cellulaire rapporteuse pourrait être utile pour découvrir des extraits de ressources naturelles et que l’extrait d’épi de Typha angustifolia identifié pourrait être utilisé dans des cosmétiques qui activent le PPAR-α, ce qui devrait améliorer la fonction cutanée.

In this study, gallium oxide (Ga2O3) nanoparticles were synthesized by sonochemical techniques at room temperature. We investigate the ultrasound irradiation conditions and the solvent type to synthesize Ga2O3 nanoparticles. γ-Ga2O3 nanoparticles were synthesized by irradiating gallium metal with ultrasound in hydrazine monohydrate solvent. The irradiation of hydrazine with ultasound suppresses the generation of ·OH, and GaOOH was not formed, and gallium metal directly oxidized. When the synthesized γ-Ga2O3 nanoparticles were heat-treated, a transition to β-Ga2O3 was observed. The heat-treated Ga2O3 nanoparticles showed excellent photocatalytic activity for the decomposition of RhB under UV irradiation.

Pseudomonas aeruginosa (P. aeruginosa) infection is one of the major causes of keratitis. However, effective prophylactic and therapeutic vaccines against P. aeruginosa keratitis have yet to be developed. In this study, we explored the use of P. aeruginosa membrane vesicles (MVs) as a prophylactic vaccine as well as the use of immune sera derived from P. aeruginosa MV-immunized animals as a treatment for P. aeruginosa corneal infections in C57BL/6 mice., C57BL/6 mice were intramuscularly immunized with P. aeruginosa MVs; the mouse corneas were then scarified and topically infected with several P. aeruginosa strains, followed by determination of corneal clinical score and corneal bacterial load. Next, immune sera derived from P. aeruginosa MV-immunized ICR mice were administered intraperitoneally to naïve C57BL/6 mice, followed by topical P. aeruginosa challenge. Finally, the immune sera were also used as a topical treatment in the mice with established P. aeruginosa corneal infections., P. aeruginosa-specific IgG and IgA antibodies induced by intramuscular immunization were detected not only in the sera but also in the eye-wash solution. Both active and passive immunization significantly inhibited P. aeruginosa corneal infection. Finally, topical treatment with immune sera in the mice with established P. aeruginosa corneal infections notably decreased the corneal clinical score and corneal bacterial load., P. aeruginosa keratitis can be attenuated by vaccination of P. aeruginosa MVs and topical application of P. aeruginosa MV-specific immune sera.

A novel intermetallic compound of the Mn–Al–Ge system, Mn(Al,Ge)5, was synthesized under high pressure and high temperature (5 GPa and 600 °C). The crystal structure was tetragonal with a space group of I4/mcm (no. 140), which was isostructural with PdGa5 or FeAl3Si2. The crystallographic parameters were refined by Rietveld analysis from powder X-ray diffraction data, yielding a = 0.624026 (5) nm, c = 0.981858 (10) nm, and Z = 4. The structure could be considered a defect-Cr5B3 (D8l) structure. The hysteresis loop and magnetization–temperature curve revealed the synthesized Mn(Al,Ge)5 to be paramagnetic: the long Mn–Mn distance led to a structure without magnetic ordering.

To determine the influence of media composition on Salmonella exclusion of Nurmi-type cultures, two and four types of cultures in the first and second trial, respectively, were prepared from the cecal contents of conventional laying hens, and Salmonella exclusion was assessed in newly hatched chicks. In the first trial, modified Viande Levure (VL) broth or nutrient broth (NB) were used to prepare Nurmi-type cultures (N-VL and N-NB), which were administered to the newly hatched chicks. Twenty-four hours later, the chicks were challenged with Salmonella enterica Typhimurium EF85-9 (ST). ST recoveries (log10 colony forming units/g of cecal contents) from the N-VL-, N-NB-, and control-treated groups 5 days after the challenge were 7.6±0.6, 0.9±1.9, and 7.7±0.4, respectively. The results suggested the influence of l-cysteine (Cys) present in the VL broth. Thus, we determined the effect of Cys in the second trial. We prepared two other cultures using VL broth without Cys (N-VL−Cys) and NB with Cys (NNB−Cys). ST recoveries from the cecal contents of the N-VL-, N-VL−Cys-, and control-treated groups were 6.3±0.9, 2.1±2.5, and 9.2±0.8, respectively. ST was not recovered from the N-NB- and N-NB−Cys-treated groups. To identify bacteria with Salmonella exclusion activity, we isolated 41 bacterial strains from the ceca of N-NB-treated chicks without Salmonella challenge. Most isolates were identified as Enterococcus faecalis or E. mundtii based on 16S rRNA gene sequencing, and only four cultures excluded Salmonella. Therefore, VL broth containing Cys was not always required for preparing Nurmi-type cultures. The use of media prepared with Cys at the lowest possible concentration or without Cys would promote to enhance Salmonella exclusion from Nurmi-type cultures.

Highlights • A landmark synthesis method of silica xerogel was proposed by ultrasonic irradiation. • Semi-solid hydrogel was irradiated ultrasonic for aging and hydrophobization. • Ultrasonic cavitation greatly accelerates aging and hydrophobization reactions. • The pore structure and density can be easily controlled by ultrasonic irradiation. • Low-density xerogels were prepared in less than 1/5 of the usual time by ultrasonic., Silica xerogels were prepared by the sol-gel method under ultrasonic irradiation, using tetraethylorthosilicate (TEOS) as the starting material. Hexamethyldisiloxane (HMDSO) was used as the hydrophobizing agent. When preparing silica xerogel, it is necessary to perform aging and hydrophobization to suppress shrinkage during ambient pressure drying, however, such treatments are time-consuming. In this study, the semi-solid hydrogel was irradiated with ultrasonic for the first time in order to accelerate aging and hydrophobic treatment, and the effect of ultrasonic frequency on structure was investigated. Firstly, ultrasonic irradiation was performed at frequencies of 100 kHz and 500 kHz, followed by hydrophobic treatment at a frequency of 500 kHz, in order to promote aging. The results identify optimum conditions for ultrasonic irradiation to promote aging and hydrophobization reactions, and it was found to be possible to prepare silica xerogels in less than 1/5 of the conventional time. The silica xerogels had a low density and the shrinkage was suppressed. In this study, it was found that ultrasonic irradiation of semi-solid hydrogel was very effective for promoting the reaction.

Diverse ascomycete fungi oxidize manganese(II) [Mn(II)] and produce Mn(III, IV) oxides in terrestrial and freshwater environments. Although multicopper oxidase (MCO) is considered to be a key catalyst in mediating Mn(II) oxidation in ascomycetes, the responsible gene and its product have not been identified. In this study, a gene, named mco1, encoding Mn(II)-oxidizing MCO from Acremonium strictum strain KR21-2 was cloned and heterologously expressed in the methylotrophic yeast Pichia pastoris. Based on the phylogenetic relationship, similarity of putative copper-binding motifs, and homology modeling, the gene product Mco1 was assigned to a bilirubin oxidase. Mature Mco1 was predicted to be composed of 565 amino acids with a molecular mass of 64.0 kDa. The recombinant enzyme oxidized Mn(II) to yield spherical Mn oxides, several micrometers in diameter. Zinc(II) ions added to the reaction mixture were incorporated by the Mn oxides at a Zn/Mn molar ratio of 0.36. The results suggested that Mco1 facilitates the growth of the micrometer-sized Mn oxides and affects metal sequestration through Mn(II) oxidation. This is the first report on heterologous expression and identification of the Mn(II) oxidase enzyme in Mn(II)-oxidizing ascomycetes. The cell-free, homogenous catalytic system with recombinant Mco1 could be useful for understanding Mn biomineralization by ascomycetes and the sequestration of metal ions in the environment

The formation of local high temperature regions, or so-called “hot spots”, in heterogeneous reaction systems has been suggested as a critical factor in the enhancement of chemical reactions using microwave heating. In this paper, we report the generation of local high temperature regions between catalyst particles under microwave heating. First, we demonstrated that reaction rate of the dehydrogenation of 2-propanol over a magnetite catalyst was enhanced 17- (250 °C) to 38- (200 °C) fold when heated with microwave irradiation rather than an electrical furnace. Subsequently, the existence of microwave-generated specific local heating was demonstrated using a coupled simulation of the electromagnetic fields and heat transfer as well as in situ emission spectroscopy. Specific high-temperature regions were generated at the vicinal contact points of the catalyst particles due to the concentrated microwave electric field. We also directly observed local high temperature regions at the contact points of the particles during microwave heating of a model silicon carbide spherical material using in situ emission spectroscopy. We conclude that the generation of local heating at the contact points between the catalyst particles is a key factor for enhancing fixed-bed flow reactions under microwave irradiation.

Serratia marcescens ATCC 274 produces the red pigment prodigiosin and the biosurfactant serrawettin W1 at 30°C but not at 37°C. A complete, high-quality genome sequence of S. marcescens ATCC 274 was obtained and found to comprise a single 5,148,533-bp circular genome with 4,799 genes.

In this study, we investigated the effects of the sheet texture of the Mo underlayer on the c-axis texture of the high-rate-sputtered Nd2Fe14B phase. The magnetic properties revealed that the squareness of the Nd–Fe–B magnetic layer did not depend on the sheet texture of the Mo underlayer but on the substrate temperature: large squareness was obtained when the magnetic layer was sputtered at high substrate temperature above 500 °C. In-plane X-ray diffraction measurements indicated that the intensity of diffraction from the Nd2Fe14B (410) plane did not depend on the sheet texture of the Mo underlayer but on the substrate temperature: high intensity was obtained when the magnetic layer was sputtered at above 500 °C, which was consistent with magnetic properties. These results support that the c-axis texture of the high-rate-sputtered magnetic layer was driven by the c plane with the lowest surface energy among the crystal planes in the Nd2Fe14B phase.

Eutectic BaTiO3/CoFe2O4 was synthesized using a developed BN diffuser by containerless microwave processing. The crystallized BaTiO3 and CoFe2O4 was obtained from melt of quinary system Ba-Ti-Co-Fe-O. Samples included eutectic BaTiO3/CoFe2O4 structure with fine dendrite structure and primary crystal of CoFe2O4. The microstructure became finer with decreasing the weight ratio of CoFe2O4. The microstructure was finer in solidification with levitation than in solidification without levitation.

Thermochemical fuel production is expected to improve CO2 utilization, and two-step chemical looping processes such as those driven by solar energy are being investigated extensively. In this study, CO2 splitting was performed under microwave irradiation using iron oxides (Fe3O4 and FeO) as the reducing agents. In addition, honeycomb-like pellets of the oxides were used to increase the contact area with the CO2 gas and prevent sintering at high temperatures. The microwave radiation could heat both Fe3O4 powder and the honeycomb-like pellets of the two iron oxides rapidly. The kinetics of the reduction of CO2 to CO under microwave irradiation were investigated by in-situ gas analysis. The apparent activation energy as calculated from the Arrhenius plot was 76.1 kJ/mol for the Fe3O4 powder, 48.3 kJ/mol for the honeycomb-like FeO pellets, and 25.3 kJ/mol for the honeycomb-like Fe3O4 pellets. The proposed microwave-based process for CO2 splitting using honeycomb-like pellets is a promising one for the processing of large amounts of CO2 gas per unit time.

A novel Mn4+-doped aluminate red phosphor Sr2Al6O11:Mn4+ was synthesized by a solid-state reaction, and we investigated its photoluminescence properties. Sr2Al6O11, which has a similar structure to Sr4Al14O25, was formed as the main phase after heating alpha-alumina, strontium carbonate, manganese dioxide, and magnesium oxide with 2.5% B2O3 at 1000 °C for 12 h or more. The Sr2Al6O11:Mn4+ phosphor exhibited red photoluminescence with peaks at around 652 and 665 nm, which arise from the spin-forbidden transition of the Mn4+ cation from the 2E to the 4A2 state. The phosphor can be excited by near ultraviolet or blue LED light because it had a broad excitation band from the near-ultraviolet to the blue light region. The emission intensity was increased by co-doping with Mg2+ cations, which act as charge compensators. The amount of Mg required for the most effective charge compensation was 10 times the optimum Mn concentration. From these results, we confirmed that Sr2Al6O11 could act as the host structure for Mn4+-doped phosphors.

Lowering the reduction temperature of iron oxide is of great significance in applied engineering, but challenging to achieve in a hydrogen tube furnace as the partial pressure of hydrogen is limited to 1 ​atm. In this study CaH2 was used as a drying agent to control the partial pressure of water vapor to lower the reduction potential of iron oxide. By comparing the extent of formation of the reduction product α-Fe in Fe3O4 reduced under hydrogen with and without CaH2 at various temperatures, the presence of CaH2 was shown to lower the temperature required for complete reduction from 400 ​°C to 300 ​°C accompanied by an increase in the H2/H2O ratio of the outlet gas. Thermodynamic calculations indicated that the addition of CaH2 increases the reduction potential, causing a higher production ratio of α-Fe. These findings indicate that CaH2 promotes reduction by efficiently absorbing the water vapor generated during reduction.

Solid solution phosphors in which the octahedral sites Mg 2 TiO 4 :Mn 4+ were substituted by Al 3+ and Sn 4+ were synthesized and the relationship between the coordination environment of Mn 4+ and the emission wavelength was investigated. Mn 4+ -doped Mg 2 TiO 4 -MgAl 2 O 4 and Mg 2 TiO 4 -Mg 2 SnO 4 red phosphors were prepared by a solid-state reaction. Mg 2- x Ti 1- x Al 2 x O 4 :Mn 4+ and Mg 2 Ti 1- y Sn y O 4 :Mn 4+ were synthesized at 1400 °C and 1200 °C, respectively. The crystal structure parameters were refined using the RIETAN-FP program and the average bond lengths were calculated from the refined crystal structures of Mg 2- x Ti 1- x Al 2 x O 4 :Mn 4+ and Mg 2 Ti 1- y Sn y O 4 :Mn 4+ . The emission peak of the Al-substituted sample shifted toward shorter wavelengths with increasing Al concentration, whereas the emission peak of the Sn-substituted sample shifted toward longer wavelengths with increasing Sn concentration. In the 2 E→ 4 A 2 transition, the emission peak wavelength of the Mn 4+ -activated spinel-type solid solution increased almost linearly with increasing average bond length between cation and anion in octahedral sites, L oct . These results indicate that there is a strong positive correlation between L oct and the emission peak wavelength for the solid solution compositions studied in this work.

Novel Mn 4+ -doped magnetoplumbite-related aluminate X-type Ca 2 Mg 2 Al 28 O 46 and W-type CaMg 2 Al 16 O 27 red phosphors were synthesized by solid-state reaction, and we investigated their photoluminescence properties. X-type Ca 2 Mg 2 Al 28 O 46 :Mn 4+ and W-type CaMg 2 Al 16 O 27 :Mn 4+ exhibited red photoluminescence, with peaks at 655 and 656 nm, arising from the spin-forbidden 2 E→ 4 A 2 transition of Mn 4+ under near-ultraviolet and blue light excitation, respectively. Therefore, these red phosphors can be excited by near ultraviolet or blue LED light. The photoluminescence properties of these phosphors were similar because magnetoplumbite-related structures crystallize similarly, forming structures consisting of stacked S and R blocks. From these results, we confirmed that magnetoplumbite-related compounds can act as the host structure for Mn 4+ -doped phosphors.

SiC fiber-MO2 (M = Ce, Zr) mixtures with various compositions were heated by applying an 80 W microwave electric field, to investigate their heating rate, maximum temperature, and dielectric constant. For the SiC fiber-CeO2 mixture, all three parameters continued to increase as the weight ratio of the SiC fiber increased, in contrast, for the SiC fiber-ZrO2 mixture, these parameters reached a maximum value at a certain composition. A thermal gradient of 500 &deg, C was observed at a microlevel in the SiC fiber-ZrO2 mixture, and hot spots were located in regions with a certain composition. This result not only contributes to designing a novel good microwave absorber but also presents new aspects with regard to high-temperature microwave processing, including the mechanism behind the high-temperature gradients on the order of micrometers as well as engineering applications that utilize these high-temperature gradients.

[EN] Concentration of microwave E-field between material particles is considered to cause the enhancement of sintering1 and chemical reaction under microwave irradiation. For example, it is usually required 1700 °C to synthesize AlN by carbothermal reduction method using Al2O3 as a starting material, but microwave processing can proceed this process at 1200 °C2. To understand this phenomenon, it is necessary to understand an occurrence behavior of plasma and a chemical reaction related to radical species generated by a local E-field concentration. In addition, in material synthesis using a raw material powder of several mm, it is suggested that a selective heating in the powder scale occurs. However, to discuss this selective heating behavior on this scale, it is necessary to realize a quantitative temperature measurement system with independent of the emissivity of the material and several mm spatial resolution. In this study, we conducted an in-situ spectroscopy and two-color thermography to verify these non-equilibrium effects during microwave irradiation. For example, in the iron making process, it was investigated that CN plasma was generated, and this CN radical contributed to the reduction reaction (Fig. 1(a))3. In addition, the developed two-dimensional two-color thermography system with a high resolution of 8.8 mm/pixel was enable to discuss local temperature gradients quantitatively (Fig. 1(b))., This work was supported by a JSPS Grant-in-Aid for Scientific Research (S) No. JP17H06156.

Scandium is being explored as an alloying element for aluminium alloys, which are gaining importance as high-performance lightweight structural alloys in the transportation industry. Sc-rich ScAlN thin films show strong piezoelectricity and can be fabricated on a hard substrate for use as wideband surface acoustic wave filters in next-generation wireless mobile communication systems. However, the use of ScAlN thin films in microelectromechanical system devices is limited by the high cost of metallic Sc, which is due to the difficulty in smelting of this material. Here, we propose a novel microwave irradiation process for producing Al-Sc alloys, with Mg ions as a reducing agent. Although scandium oxide is thermodynamically stable, intermetallic Al3Sc is obtained in high yield (69.8%) via a low-temperature (660 °C) reduction reaction under microwave irradiation. Optical spectroscopy results and thermodynamic considerations suggest a non-thermal equilibrium reaction with the univalent magnesium ions excited by microwave irradiation.

Chemical reactions performed under microwave irradiation often demonstrate high reaction rates, high selectivity, and low reaction temperatures, which allows for more compact reactors and more energy-efficient processes than used in conventional heating methods. In this study, we discovered a new chemical reaction and proposed a new material synthesis method, performed using a solid-state microwave source with an oscillator and a single-mode cavity. We developed a microwave heating thermogravimetry apparatus to confirm that microwave irradiation reduced the temperature of the reduction process. Next, we applied this apparatus to the reduction process of copper oxide with carbon as the reducing agent and compared microwave heating with conventional heating. We demonstrated that the reduction temperature of microwave heating was 192 °C in a magnetic (H) field and 265 °C in an electric (E) field, which were lower than those of conventional heating. For microwave heating in the E-field, plasma strongly affected the reaction process, leading to a reduction in the reaction temperature. For microwave heating in the H-field, localized heating occurred and the average reaction temperature was lower. Using the obtained results, an applicator suitable for these modes can be designed, enabling a reduction process with an additional energy-saving effect.

Reaction kinetics during microwave H-field heating and electric furnace heating were investigated to verify the effect of rapid heating and the non-thermal microwave effect. This work is focused on the ferromagnetic material NiMn2O4, and the reduction reaction under rapid heating is investigated using an in situ analysis device. The results showed that the activation energy varied with the heating rate under microwave H-field irradiation, and it was the same as that in an electric furnace when the heating rate was the same. On the other hand, under microwave H-field irradiation, the reduction reaction began from a significantly low temperature compared with that of electric furnace heating. The results suggest that the transition theory during microwave irradiation should be expanded to include the effect of spin waves excited by a microwave H-field on magnetic materials.

The microstructure and magnetic properties of Nd 2 Fe 14 B crystallized by microwave heating were investigated to reveal the effect of microwave on the microstructure. The c -axis oriented and nano-sized columnar grains of Nd 2 Fe 14 B were obtained through microwave processing. The oriented texture was limited to the surface region. This microstructure could not be observed through conventional heating. It was considered that the temperature gradient caused by microwave heating was responsible for the formation of columnar grains. In addition to the change in the microstructure resulting from the heating methods, the coercivity and remanence of the microwave irradiated sample was larger than those obtained via conventional heating.

Ti-doped SrLaAlO4 green-emitting phosphor was synthesized via solid-state reactions in air and N2 atmosphere. Sample heated in air showed no emission, however, sample heated in N2 showed broad green emission around 492 nm and broad near-infrared emission around 950 nm by 321 nm near-ultraviolet excitation. XPS measurement and UV-Vis diffuse reflectance spectra suggest that Ti in the sample was reduced to Ti3+ state when the sample was heated in N2. Possible emission mechanism of the sample can be explained as O2-–Ti3+ charge-transfer transition.

Mn4+-doped magnetoplumbite-type BaMg6Ti6O19 and spinel-type Mg2TiO4 red phosphors were synthesized by a solid-state reaction. BaMg6Ti6O19:Mn4+ and Mg2TiO4:Mn4+ were formed as main phase above 1200 oC. Although the emission peak of BaMg6Ti6O19:Mn4+ and Mg2TiO4:Mn4+ were almost the same, the excitation peak of BaMg6Ti6O19:Mn4+ and Mg2TiO4:Mn4+ were different. The 4A2→4T1 transition peak of Mg2TiO4:Mn4+ shifted to a shorter wavelength side than that of BaMg6Ti6O19:Mn4+ and 4A2→4T2 shifted to a longer wavelength side. The crystal field splitting energy of Mg2TiO4:Mn4+ was lower than that of BaMg6Ti6O19:Mn4+. By the additional of R block, the racah parameter B increased and C decreased. Although the increase of B causes a blue-shift of the emission wavelength and the decrease of C causes a red-shift of the emission wavelength, PL emission wavelength was little different due to the influence of both racah parameter. Thus, it was suggested that the existence of R block results in a difference of photoluminescence properties.

Aluminum nitride (AlN) was synthesized by carbothermal reduction and nitridation method from a mixture of various transition alumina powders and carbon black using 2.45 GHz microwave irradiation in N2 atmosphere. We achieved the synthesis of AlN at 1300–1400°C using 2.45 GHz microwave irradiation for 60 min. Our results suggest that θ-Al2O3 is more easily nitrided than γ-, δ-, and α-Al2O3. On the other hand, nitridation ratio of samples synthesized in a conventional furnace under nitrogen atmosphere were zero or very low. These results show that 2.45 GHz microwave irradiation enhanced the reduction and nitridation reaction of alumina.

The reduction behavior of copper (II) oxide (CuO) covered with boron nitride (BN) powder under microwave H-field irradiation was investigated to understand the mechanism of enhanced reduction of CuO in microwave processing. Internal heating using microwave irradiation resulted in a unidirectional diffusion of oxygen from inside the CuO pellet to its outside, and selective heating prevented the oxidization of the BN powder near the CuO pellet. A quantum chemical interpretation of this phenomenon revealed that the microwave H-field couples to the Fermi level electrons of CuO, and the copper-oxygen bond may be cleaved by both microwave energy and thermal energy. As a result, microwave H-field irradiation resulted in a more effective reduction of CuO to copper metal compared to conventional heating.

To apply Nd–Fe–B thin films for mass-produced heat-assisted magnetic recording media, we investigated the high-rate sputtering conditions required to obtain c-axis textured Nd2Fe14B thin films and ...

Homologous compounds, Fe 2 O 3 (ZnO) m , with a modulated natural superlattice structure, were synthesized within 10 min at 1200 °C in a simple solid-state reaction under 2.45 and 28 GHz microwave irradiation. Transmission electron microscopy and energy dispersive X-ray spectroscopy results revealed that m decreased with increasing the synthesis temperature and microwave frequency. In the Zn–Fe–O system, γ-Fe 2 O 3 was heated in H and E-field and ZnO was heated in E-field under 2.45 GHz microwave irradiation. However, α, γ-Fe 2 O 3 and calcined ZnO were heated under 28 GHz microwave irradiation. This selective microwave heating resulted in the different diffusion conditions than conventional heating; therefore, homologous compounds with low m values were rapidly synthesized at low temperature.

A new facile process has been developed to synthesize silver nanowire transparent conductive films by reducing high-aspect-ratio, needle-shaped silver carboxylates, prepared as the precursor, while retaining their morphology. Nanowire precursors are simply obtained by ultrasound irradiation when silver (I) oxide and carboxylic acids are used as starting materials. The aspect ratio of the precursors is increased when the ultrasound irradiation is followed by microwave irradiation. Silver nanowires can be easily obtained by reducing these precursors with hydrazine gas or irradiating them with Ar plasma for a short time. The morphology of the resulting nanowires is different from that of typical nanowires that have been reported. The nanowires have porous morphology, where small nanoparticles are connected to form nanobeadwire. The nanobeadwire is considered to increase the transparency of the film because of its rough morphology. This new method can synthesize silver nanobeadwires and fabricate the transparent conductive film simultaneously, in one-step, so that it can significantly simplify manufacturing processes.

Microwaves are not a simple heat source. Substances are heated directly by electromagnetic waves at energies commensurate with microwaves. Therefore, an understanding of the nature of these electromagnetic waves is the dominating discussion on microwave heating. Moreover, the coffee break continues the discussion regarding relationships between microwaves and foods, and the history of microwave cooking ovens. The chapter explains the basics of electromagnetic waves and how these electromagnetic waves are being used. Furthermore, the characteristics of microwaves in electromagnetic waves are clarified. The coffee break describes the use of microwaves at various frequencies.

Microwave heating generates heat by absorption and loss of energy. Accordingly, how does a substance turn microwave into heat? How does one measure the efficiency of microwave heating? These topics require to be understood. As such, this chapter provides some commentaries on these topics. Furthermore, a method for measuring the heating efficiency of microwaves, impedance matching, is also explained. There are books out there that presume that microwave heating refers to heating in which dielectric heating proceeds. This is not entirely correct, as there are several types of microwave heating phenomena. This chapter also describes the type of microwave heating through illustrations and some equations. Furthermore, actual examples and chemical reactions are given; such topics as the penetration depth of microwaves, the skin effect, the frequency effect, simulation of electromagnetic waves, and electrothermal and transmission modes are discussed. The coffee break shows the proper usage of microwave ovens.

Microwave dielectric heating has been used for various purposes for well over five decades. This chapter thus introduces historical trends on the use of these electromagnetic waves in not only domestic microwave ovens but also more importantly applied in such fields as microwave chemistry and materials processing, as well as being envisioned in solar power satellite (SPS) systems. Furthermore, the chapter classifies the industrial fields in which microwave heating is used and shows a summary of the application fields of microwave chemistry and materials. In addition, overviews are given of microwaves being used in organic synthesis, polymer synthesis, catalyzed reactions, sintering of ceramics, heating of metals, extraction, and discharge electrodeless lamps. A coffee break talks about the Raytheon Corporation where the microwave ovens were first created.