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Crystalline silica is an important cause of serious pulmonary diseases, and its toxic potential is known to be associated with its surface electrical properties. However, in vivo data clarifying the relevance of silica's toxic potential, especially its long-term effects, remain insufficient. To investigate the contribution of physico-chemical property including surface potential on the hazard of nanocrystalline silica, we performed single intratracheal instillation testing using five different crystalline silicas in a rat model and assessed time-course changes in pulmonary inflammation, lung burden, and thoracic lymph node loads. Silica-nanoparticles were prepared from two commercial products (Min-U-Sil5 [MS5] and SIO07PB [SPB]) using three different pretreatments: centrifugation (C), grinding (G), and surface dissolving (D). The five types of silica particles-MS5, MS5_C, SPB_C, SPB_G, and SPB_D-were intratracheally instilled into male F344 rats at doses of 0 mg/kg (purified water), 0.22 mg/kg (SPB), and 0.67, 2, or 6 mg/kg (MS5). Bronchoalveolar lavage, a lung burden analysis, and histopathological examination were performed at 3, 28, and 91 days after instillation. Granuloma formation was present in MS5 group at 91 days after instillation, although granuloma formation was suppressed in MS5_C group, which had a smaller particle size. SPB_C induced severe and progressive inflammation and kinetic lung overload, whereas SPB_G and SPB_D induced only slight and transient acute inflammation. Our results support that in vivo toxic potential of nanosilica by intratracheal instillation may involve with surface electrical properties leading to prolonged effect and may not be dependent not only on surface properties but also on other physico-chemical properties.

A simple, area-specific coating technique for fluoridated apatite (FAp) on teeth would be useful in dental applications. Recently, we achieved area-specific FAp coating on a human dentin substrate within 30 min by a laser-assisted biomimetic (LAB) process; pulsed Nd:YAG laser irradiation in a fluoride-containing supersaturated calcium phosphate solution (FCP solution). The LAB-processed, FAp-coated dentin substrate exhibited antibacterial activity against a major oral bacterium, Streptococcus mutans. In the present study, we refined the LAB process with a combination of a dental diode laser and a clinically approved light-absorbing molecule, indocyanine green (ICG). A micron-thick FAp layer was successfully formed on the dentin surface within only 3 min by the refined LAB process, i.e., dental diode laser irradiation in the FCP solution following ICG treatment. The ICG layer precoated on the dentin substrate played a crucial role in inducing rapid pseudo-biomineralization (FAp layer formation) on the dentin surface by absorbing laser light at the solid-liquid interface. In the refined LAB process, the precoated ICG layer was eliminated and replaced with the newly formed FAp layer composed of vertically oriented pillar-like nanocrystals. Cross-sectional ultrastructural analysis revealed a smooth interface between the FAp layer and the dentin substrate. The refined LAB process has potential as a tool for the tooth surface functionalization and hence, is worth further process refinement and in vitro and in vivo studies.

Ag@TiO2 nanoparticles (NPs) with Ag metal cores and TiO2 semiconductor shells were prepared with a hydrothermal method and their structure was characterized by scanning electron microscopy, transmi...

To evaluate the feasibility of short whole-body bone scan acquisition times using a novel gamma camera with cadmium-zinc-telluride (CZT) semiconductor detectors. We retrospectively enrolled 78 consecutive patients with prostate cancer who underwent bone scintigraphy using a whole-body gamma camera with CZT detectors. After acquisition of list-mode data with 180 s per bed position, anterior and posterior whole-body images were reconstructed using the first 5%, 10%, 25%, 50%, 75% and 100% of the list-mode data. Two experienced nuclear medicine physicians interpreted the images, and interrater agreement and the diagnostic value of the images were determined. Quantitative artificial neural network (ANN) values, bone scan indexes (BSI) and hotspot numbers (HsN) were also calculated by automated diagnostic software. Excellent interrater reliabilities of the visual assessments were obtained for the 100%, 75%, 50%, and 25% images (κ = 0.88, 0.88, 0.88 and 0.88, respectively). The 5% images also showed high diagnostic value (sensitivity 0.94, specificity 0.84 and accuracy 0.86). Intraclass correlation coefficients (ICC) between the 100% images and the reduced acquisition time images were evaluated in quantitative analyses, and excellent correlations were observed for ANN value in the 75% images (ICC 0.77), for BSI in all the reduced acquisition time images (75%, 50%, 25%, 10% and 5%; ICC 0.99, 0.99, 0.99, 0.96 and 0.75, respectively), and for HsN in the 75%, 50%, 25% and 10% images (ICC 0.99, 0.99, 0.98 and 0.90, respectively). Whole-body gamma cameras with CZT detectors have the potential to reduce image acquisition times and the dose of radioisotope injected for bone scans.

The biocompatibility and osteoconductivity of metallic biomaterials can be achieved by calcium phosphate (CaP) coating. We recently developed a laser-assisted biomimetic (LAB) process for rapid and area-specific CaP coating on several materials. In the present study, the LAB process was applied to cobalt&ndash, chromium (Co&minus, Cr) alloy, a metallic biomaterial widely used in orthopedic and dental applications. The LAB process was conducted by irradiation of unfocused pulsed laser light onto the substrate immersed in supersaturated CaP solution. The LAB-processed substrate formed CaP on the irradiated surface within only 5 min and was coated with a micron-thick CaP layer within 30 min by the effects of laser-induced surface modification and heating. Ultrastructural analysis with transmission electron microscopy revealed that the resultant CaP layer was integrated with the underlying substrate through two intermediate layers, an upper chromium oxide layer and a lower Co-rich (Cr-deficient) alloy layer. The CaP layer was loaded with a large number of cobalt chromite (CoCr2O4) nanoparticles. The results obtained offer new insights into the mechanism of CaP coating in the LAB process and future applications of LAB-processed Co&minus, Cr alloys.

Background: Crystalline silica is an important cause of serious pulmonary diseases. The relationship between this hazard and various physicochemical parameters of crystalline silica has been studied for more than a century, and the toxic potential of silica is known to be associated with its surface properties. However, no in vivo dataset has yet been accumulated to clarify the relevance of this, especially regarding longer term effects. To provide new insights into these longer term effects, we performed single intratracheal instillation testing of five different crystalline silicas and assessed the time-course changes in pulmonary inflammation, lung burden, and thoracic lymph node loads. The tested silicas were prepared from two commercial products [Min-U-Sil5 (MS5, US Silica Company) and SIO07PB (SPB, Kojundo Chemical)] by using three different pretreatment steps: centrifugation (C), grinding (G), and surface dissolving (D). The five types of silica particles—MS5, MS5_C, SPB_C, SPB_G, and SPB_D—were suspended in purified water and intratracheally instilled into male F344 rats. Bronchoalveolar lavage, lung burden analysis, and histopathological examination were performed 3, 28, and 91 days after instillation.Results: MS5 and MS5_C provoked similar biphasic inflammation that differed in severity: MS5 induced granuloma generation 91 days after instillation, whereas the smaller particles of MS5_C elicited only macrophage aggregation. SPB_C induced severe and persistent inflammation, whereas SPB_G and SPB_D induced only slight and transient acute inflammation. All of the silicas were dose-dependently retained in the lung. Silicas that induced prolonged responses were translocated to the thoracic lymph nodes as early as 28 days after instillation. Those that induced transient inflammation were removed effectively from the lung with very little lymph node retention. No quantitative association was identified between lung retention and physicochemical properties, although common features of the retained materials seemed to be reduced solubility, similar surface properties, and relatively small particle. Conclusion: Our key findings suggest that prolonged silica toxicity occurs through lymph node retention. Although the main drivers of translocation to the lymph nodes have not yet been clarified, we provide in vivo evidence of the contributions of at least silica solubility, surface properties, and particle size.

Atomically dispersed Pd additives significantly enhanced the hydrogen sensing performance of a Co

In this work taking Au/MxOy (M = Fe, Co, Ni) particles as examples, we investigate and discuss the physical processes involved in particles formation by laser irradiation of mixture of two different kinds of nanoparticles dispersed in liquids. We showed that this method is an efficient and universal way for synthesis and control a variety of composite particles with various morphology (core–shell, alloy) and compositions which are not only metals or oxides but also nonequilibrium bimetallic alloys (AuFe, AuCo, and AuNi). Additionally, fluence diagrams which were designed to show the relation between laser fluence and particle diameter plot based on the heating–melting–evaporation model are useful for better understanding of the mechanism of composite particles formation during pulsed laser irradiation. To the extent of our knowledge, this is the first explanation of the mechanism of Au-based composite particles formation during pulsed laser irradiation of mixture of two different raw nanomaterials dispers...

This chapter explains how to prepare stable nanomaterial dispersion samples and the characterization techniques. The explanation is focused on practical techniques rather than scientific studies. Several technical terms and definitions are explained and effective lab apparatuses are introduced for the better understanding. First, a standard sample preparation method with the typical experimental conditions is described and several actual nanomaterial examples (TiO2, NiO, SiO2, CeO2, and ZnO) are introduced.

A technique for implementing biocompatible and antibacterial functions to a targeted region on tooth surfaces has potential in dental treatments. We have recently demonstrated pseudo-biomineralization, i.e., the growth of an apatite layer on a human dentin substrate by a laser-assisted biomimetic (LAB) process, based on pulsed laser irradiation in a supersaturated CaP solution. In this study, pseudo-biomineralization was induced in the presence of fluoride ions using the LAB process in order to fabricate an antibacterial fluoride-incorporated apatite (FAp) layer on the dentin surface. After processing for 30 min, a micron-thick FAp layer was formed heterogeneously at the laser-irradiated solid−liquid interface via pseudo-biomineralization. A time-course study revealed that the LAB process first eliminated the pre-existing organic layer, while allowing fluoride incorporation into the dentin surface within 1 min. Within 5 min, FAp nanocrystals precipitated on the dentin surface. Within 30 min, these nanocrystals acquired a pillar-like structure that was weakly oriented in the direction normal to the substrate surface to form a dense micron-thick layer. This layer was integrated seamlessly with the underlying dentin without any apparent gaps. The FAp layer exhibited antibacterial activity against a major oral bacterium, Streptococcus mutans. The proposed LAB process is expected to be a useful new tool for tooth surface functionalization via facile and area-specific pseudo-biomineralization.

Amorphous calcium phosphate (ACP) plays an important role in biomineralization within the three-dimensional (3D) collagen network in human hard tissues, and exhibits osteoconductivity. Porous collagen sponges coated with ACP nanoparticles could be considered as potential scaffolds for use in bone tissue engineering. In this study, such composite materials were fabricated via homogeneous ACP precipitation using a supersaturated calcium phosphate (CaP) solution. Homogeneous ACP precipitation was induced in situ within the sponges by a temperature-controlled coating process composed of two steps. In the first step, the CaP solution was cooled to 4 °C to suppress precipitation until the solution penetrated fully into the sponge's internal pores. In the second step, the CaP solution was warmed up to 25 °C with continuous shaking to induce ACP precipitation within the sponges. The resulting sponges were therefore coated with ACP nanoparticles on their inner and outer surfaces. A simulated body fluid (SBF) test indicated osteoconductivity of the collagen sponges coated with ACP nanoparticles. Further, ACP-coated collagen sponges immobilizing basic fibroblast growth factor (bFGF) were fabricated using the CaP solution supplemented with bFGF. The fabricated sponges allowed the sustained release of bFGF in a culture medium and enhanced proliferation of osteoblastic MC3T3-E1 cells. Such ACP-coated collagen sponges have the potential to be used as scaffolds in bone tissue engineering if pursued for further in vitro and in vivo studies.

Surface functionalization of teeth with fluoride-incorporated apatite layers displays great potential in treatments and prevention of dental disorders. In this study, we used a sintered hydroxyapatite (sHA) substrate as a model material of teeth, and established a rapid and area-specific coating technique of fluoride-incorporated apatite layers by using a laser-assisted biomimetic (LAB) process. In this technique, a sHA substrate was irradiated on the surface with a Nd:YAG pulsed UV laser for 30 min in supersaturated calcium phosphate (CaP) solutions with various fluoride concentrations. The fluoride concentration in the CaP solution was varied to control morphology, crystalline structure, and fluoride content of the resulting layers. Without fluoride in the CaP solution, an octacalcium phosphate (OCP) layer with a flake-like structure was formed on the laser-irradiated surface of the substrate. The addition of fluoride (1000 µM and 3000 µM) to the CaP solution led to the formation of fluoride-incorporated apatite layers with an enamel-like needle-like nanostructure. The fluoride-incorporated apatite layers adhered firmly to the sHA surface and reduced acid dissolution of the sHA substrate by acting as a protective covering. Additionally, the layers released fluoride ions for more than 24 h, and exhibited antibacterial activity relative to a caries-causing bacterium, namely Streptococcus mutans. Thus, our LAB process can potentially act as a new tool for functionalization of tooth surfaces. Statement of Significance We used a sintered hydroxyapatite (sHA) substrate as a model material of teeth, and established a rapid and area-specific coating technique of fluoride-incorporated apatite layers on the sHA surface by using our laser-assisted biomimetic (LAB) process. In this process, pulsed laser was utilized to accelerate seeded crystal growth in supersaturated calcium phosphate solutions supplemented with NaF. The thus-fabricated fluoride-incorporated apatite layers consisted of enamel-like needle-like nanocrystals with c-axis orientation. These fluoride-incorporated apatite layers adhered firmly to the sHA surface, reduced acid dissolution of the sHA substrate by acting as a protective covering, and exhibited antibacterial activity against Streptococcus mutans through the fluoride release. Thus, our LAB process can potentially act as a new tool for functionalization of tooth surfaces.

The structures and morphologies of Al-rich Al–Au alloy nanoparticles thermally oxidized under gaseous oxygen mixtures were investigated by transmission electron microscopy while varying the temperature and oxygen exposure conditions. The exposure of alloy nanoparticles to oxygen at room temperature formed amorphous alumina coatings that protected unoxidized core metals against further oxidation up to approximately 1000 °C. Above this temperature, Au–γ-Al2O3 Janus nanoparticles were generated as a result of complete oxidation. In contrast, the direct oxidation of preheated alloy nanoparticles without oxide coatings enabled complete oxidation to proceed at temperatures as low as 575 °C. Under lower oxygen pressures, direct oxidation resulted in the formation of Au–γ-Al2O3 Janus NPs with worm-like morphologies, suggesting anisotropic oxide growth via interfacial oxidation. In a similar manner, Pt–γ-Al2O3 Janus NPs were generated by the direct oxidation of Al–Pt alloy NPs.

Gold nanoparticles were deposited on two kinds of solid acids, i.e., amorphous SiO 2 –Al 2 O 3 and cation-exchange resin Amberlyst-15; the resultant materials exhibited high activity as metal–acid bifunctional catalysts. SiO 2 –Al 2 O 3 was impregnated with a chloride-free alkaline Au(III) solution containing Na + and then dried. After calcination at 623 K, gold nanoparticles with diameters of 4.2 nm (measured by X-ray diffraction) were deposited at a Au loading of 1.0 wt%. By replacing the Na + ions with H + ions through ammonium ion-exchange and heating, an acidic Au/SiO 2 –Al 2 O 3 catalyst was obtained. In Amberlyst-15, gold nanoparticles with diameters of 7.3 nm were deposited after impregnation and drying. Subsequent ion-exchange with dilute sulfuric acid generated the acidic form of the Au/Amberlyst-15 catalyst, which showed an esterification activity equivalent to that of the original Amberlyst-15. The catalyst exhibited high activity for the direct conversion of cellobiose to gluconic acid, which requires both acid hydrolysis and oxidation. A 45% yield of gluconic acid was obtained after 24 h of reaction under ambient air at 373 K, with an apparent synergistic effect between the gold nanoparticles and acidic resin surface.

Organic semiconductors are attracting increasing interest as flexible thermoelectric materials owing to material abundance, easy processing and low thermal conductivity. Although progress in p-type polymers and composites has been reported, their n-type counterpart has fallen behind owing to difficulties in n-type doping of organic semiconductors. Here, we present an approach to synthesize n-type flexible thermoelectric materials through a facile electrochemical intercalation method, fabricating a hybrid superlattice of alternating inorganic TiS2 monolayers and organic cations. Electrons were externally injected into the inorganic layers and then stabilized by organic cations, providing n-type carriers for current and energy transport. An electrical conductivity of 790 S cm(-1) and a power factor of 0.45 mW m(-1) K(-2) were obtained for a hybrid superlattice of TiS2/[(hexylammonium)x(H2O)y(DMSO)z], with an in-plane lattice thermal conductivity of 0.12 ± 0.03 W m(-1) K(-1), which is two orders of magnitude smaller than the thermal conductivities of the single-layer and bulk TiS2. High power factor and low thermal conductivity contributed to a thermoelectric figure of merit, ZT, of 0.28 at 373 K, which might find application in wearable electronics.

We developed a laser fabrication process of submicrometer hollow fluorescent spheres of Tb3+-incorporated calcium phosphate. Pulsed laser irradiation was applied to a dispersion of carbon-integrated hydroxyapatite nanopowders in the presence of Tb3+. Thus, Tb3+ incorporation during calcium phosphate sphere formation through laser processing was achieved.

A technique for tooth surface modification with biocompatible calcium phosphate (CaP) has huge potential in dental applications. Recently, we achieved a facile and area-specific CaP coating on artificial materials by a laser-assisted biomimetic process (LAB process), which consists of pulsed laser irradiation in a supersaturated CaP solution. In this study, we induced the rapid biomineralization on the surface of human dentin by using the LAB process. A human dentin substrate was immersed in a supersaturated CaP solution, then its surface was irradiated with weak pulsed laser light for 30 min (LAB process). Ultrastructural analyses revealed that the pristine substrate had a demineralized collagenous layer on its surface due to the previous EDTA surface cleaning. After the LAB process, this collagenous layer disappeared and was replaced with a submicron-thick hydroxyapatite layer. We believe that the laser irradiation induced pseudo-biomineralization through the laser ablation of the collagenous layer, followed by CaP nucleation and growth at the dentin–liquid interface. The mineralized layer on the dentin substrate consisted of needle-like hydroxyapatite nanocrystals, whose c-axes were weakly oriented along the direction perpendicular to the substrate surface. This LAB process would offer a new tool enabling tooth surface modification and functionalization through the in situ pseudo-biomineralization.

An easy and versatile method for the preparation of gold nanoparticles catalyst from aqueous alkaline solution of chloride-free gold acetate has been developed. Au nanoparticles can be deposited on various supports only by impregnating them with the stocked solution of it and by the following calcination. Although the solubility of gold acetate is considerably low in water, we have successfully dissolved it completely by refluxing the brown colloidal dispersion of gold acetate with a pH adjusted to 10–11 at the boiling temperature. The resultant solution was transparent without any color, which should contain anionic Au(III) species like Au(OH) 4 − . Metal oxide powder such as Al 2 O 3 , CeO 2 , TiO 2 , SiO 2 as well as silicates such as saponite clay, and Y-type zeolites was impregnated with the solution and then calcined at 623 K. After washing and drying, the deposition of Au nanoparticles ( 2 prepared by this method was more active than those prepared according to conventional deposition–precipitation or impregnation methods by using HAuCl 4 as a source of gold. The smallest mean particle size of Au (2.3 ± 0.8 nm) was obtained on saponite clay, which was highly active for glucose oxidation performed in aqueous phase at 333 K.

A new one-step approach was developed to synthesize bimetallic alloy submicrometer spheres, which are immiscible under equilibrium, using AuCo as a model system. Uniform, single-phase AuCo alloy submicrometer particles (∼230 nm) with a well-defined spherical morphology were successfully formed via pulsed laser irradiation of Au and Co-oxides nanoparticles dispersed in ethanol and characterized with a combination of electron microscopy, diffraction and magnetization measurements.

Micrometer and submicrometer crystalline silicon spheres were fabricated by selective laser heating of irregular silicon particles in liquid medium. TEM, SEM, XRD, and XPS characterized the structure and morphology of the prepared silicon spheres. The results suggested that they were spherical with a single crystalline structure. In this study, the formation mechanism of the spheres is analyzed, and the process parameters are optimized to obtain high-quality silicon spheres. A theoretical deduction regarding the relationship between critical laser energy density and particle size is also discussed, by which we can predict that larger spheres can be obtained at higher laser energy densities.

Epitaxially coherent AuxCu1-x−Cu2O biphase nanoparticles (x = 0.83) were grown in free space by oxidizing AuyCu1-y alloy nanoparticles (y = 0.46) above their melting temperature. Electron-microscop...

Core-shell nanoparticles composed of ferromagnetic cobalt platinum cores covered by non-magnetic silica shells were synthesized by laser ablating a composite target in a helium background gas. The average diameter of the CoPt core was controlled by adjusting the CoPt/SiO2 ratio of the ablation target. The particles were also classified in the gas phase using an electrical mobility classifier. The present method successfully synthesized nearly monodispersed nanoparticles with an average core diameter of 2.5nm. This article describes the synthesis of the core-shell nanoparticles and investigates their magnetic properties.

Electronic structure and thermoelectric properties of noble metal clathrates Ba 8 M 6 Ge 40 (M = Cu, Ag, Au) were calculated by using a first principle based method to discuss prospect of high performance thermoelectric materials. The calculated band structures show that these clathrate compounds are degenerate semiconductors with p type carrier. The band gaps become narrow by noble metal doping. The band gap narrowing is caused by the valence band lifting due to anti-bonding nature between Ge and M, and conduction band widening due to framework-guest atom coupling via Ba orbitals at 6d sites. The thermoelectric power of Ba 8 M 6 Ge 40 increases with temperatures monotonically and the magnitude is smaller than 100 μV/K under 1000 K. The carrier concentration of Ba 8 M 6 Ge 40 is a little larger for the high performance thermoelectric materials. The carrier concentration is controlled by varying the composition of Ba 8 Au x Ge 46-x . The optimized carrier concentration in Ba 8 Au x Ge 46-x was obtained as 4.4 × 10 26 m -3 (p type) and 6.4 x 10 26 m -3 (n type), respectively.

The dielectric constant is a key parameter that determines both optical and electronic properties of materials. It is desirable to tune electronic properties though dielectric engineering approach. Here, we present a systematic approach to tune carrier mobilities of hybrid inorganic/organic materials where layered two-dimensional transition-metal dichalcogenide TiS2 is electrochemically intercalated with polar organic molecules. By manipulating the dielectric mismatch using polar organic molecules with different dielectric constants, ranging from 10 to 41, the electron mobility of the TiS2 layers was changed three times due to the dielectric screening of the Coulomb-impurity scattering processes. Both the overall thermal conductivity and the lattice thermal conductivity were also found to decrease with an increasing dielectric mismatch. The enhanced electrical mobility along with the decreased thermal conductivity together gave rise to a significantly improved thermoelectric figure of merit of the hybrid inorganic/organic materials at room temperature, which might find applications in wearable electronics.

Transmission electron microscopy was employed to elucidate the morphologies and structures of thermally oxidized gas-phase Al nanoparticles (mean diameter of 10 ± 3 nm) obtained at various temperatures and oxygen pressures. Exposure of the nanoparticles to oxygen at room temperature followed by heating to high temperatures initially generated an amorphous Al2O3 film on the particles that protected the core from further oxidation up to ~1000 °C. However, these particles were completely oxidized to γ-Al2O3 above ~1000 °C. In contrast, exposing bare, preheated Al nanoparticles to oxygen led to direct oxidation to γ-Al2O3 at temperatures as low as ~575 °C. The direct oxidation of Al nanoparticles at 900 °C under low oxygen pressures resulted in the growth of worm-shaped γ-Al2O3 nanoparticles, suggesting anisotropic oxide growth via interfacial oxidation.

Core–shell nanoparticles composed of ferromagnetic cobalt platinum cores covered by non-magnetic silica shells were synthesized by laser ablation of a composite target in a helium background gas. The average diameter of the CoPt core was controlled by adjusting the CoPt/SiO 2 ratio of the ablation target and size-classifying the nanoparticles by an electrical mobility classifier. The present method successfully synthesized nearly monodispersed nanoparticles with an average core diameter as small as 2 nm. The size-dependent magnetic properties of nano-composite films generated by the deposition of nanoparticles onto the substrate were investigated by a SQUID magnetometer.

Monodispersed CoPt alloy nanoparticles were synthesized by a pulsed laser ablation (PLA) technique coupled with a low-pressure operating differential mobility analyzer (LP-DMA). The CoPt alloy nanoparticles were generated by laser ablating a solid Co–Pt target. In CoPt alloy nanoparticles synthesized from a target with a Co composition of 75 at%, the nanoparticle surfaces were covered by an oxide layer and exhibited a core-shell structure. In contrast, no shell was observed in particles generated from a target with a Co:Pt ratio of 50:50 at%. According to an EDX analysis, the compositions of the individual nanoparticles were almost the same as that of the target material. Finally, the magnetic hysteresis loops of the CoPt alloy nanoparticles exhibited ferromagnetism.

This paper presents the method for fabricating size-selected nickel nanoparticles (diameter: 5−20 nm) coated with nickel oxide shells (thickness: about 2 nm). The core−shell particles were synthesized by a series of sequential gas-phase processes including pulsed laser ablation, aerosol postannealing, size-classification, compulsory oxidation, and aerosol-jet deposition. The change in the size distribution of the generated particles due to postannealing was measured by a low-pressure differential mobility analyzer (LP-DMA) coupled with a Faraday cup electrometer. The peak size decreased as the postannealing temperature rose, indicating that a sintering and restructuring of the agglomerates was taking place. In the high-resolution TEM (HRTEM) observation, the Ni particles of less than 15 nm in diameter were found to be spherical and single crystal after the annealing at 1073 K. The 20 nm particles were also spherical, but they remained polycrystalline due to insufficient annealing treatment required for ...

DHA含有魚油と豆乳を組み合わせた食品の摂取による, ヒトにおける抗肥満効果を身体組成, 安静時代謝量の面から検討した。健康な女子大学生34名 (年齢18-22歳) を2群に分け, 1群には1本200mL中にDHAが1,000mg含まれるようにDHA含有魚油を含むDHA含有豆乳 (以下試験飲料) を, もう1群には魚油の替わりにコーン油を含む対照飲料を6週間摂取させた。その結果, 試験飲料, 対照飲料摂取両群ともに6週間の摂取後に体重が減少し, その結果BMIも減少した。体重減少の内訳は試験飲料群では体脂肪量および除脂肪体重の両方, 対照飲料群では除脂肪体重の減少であった。臍水平断面のCTスキャンによる内臓脂肪と皮下脂肪面積をみると対照飲料摂取群では試験前後で差はみられなかったが, 試験飲料摂取群では皮下脂肪面積が有意に減少, 内臓脂肪面積も減少傾向にあった。安静時代謝量は試験飲料摂取群では3週間後に増加傾向, 6週間後には有意に増加した。一方, 対照飲料摂取群は有意な変動はみられなかった。以上の結果よりDHA含有豆乳摂取による安静時代謝量の亢進を伴う抗肥満効果が示された。

X rays have been widely used for nondestructive analysis of nano-scaled materials for a long time; however, the effects of x-ray radiation have been less extensively discussed. In this work, by means of the in-situ x-ray diffraction and the ex-situ high-resolution electron microscopy, we have quantitatively investigated the x-ray effect on the oxidation behavior of Cu nanoparticles prepared by the vapor condensation method. Clear evidence shows that the x-ray irradiation increases the oxidation thickness as well as the oxidation rate. The results are of critical importance not only for the oxidation studies but also for the nanomaterial researches with x-ray related equipment.

Efficient synthesis of l -α-phosphatidyl- d - myo -inositol 3,5-bisphosphate was achieved from 1,2,5,6-diisopropylidene- d -glucose by utilizing ring-closing metathesis and catalytic OsO 4 dihydroxylation.

Based on the solution structures of chiral bidentate lithium amides ((R)-3a,b) having a phenyl group on the chiral carbon, chiral bidentate amines ((R)-5a,b-8a,b and (S)-9a,b) having a bulkier group instead of a phenyl group on the chiral carbon were designed and synthesized.

Using chiral bidentate lithium amides having a bulky group instead of a phenyl group on the chiral carbon, enantioselective deprotonation of prochiral 4-substituted cyclohexanones in the presence of excess trimethylsilyl chloride was examined in THF in the absence and in the presence of HMPA. It is shown that enantioselectivity of the reactions decreases as the substituent on the chiral carbon of the chiral lithium amides and the substituent at the 4-position of cyclohexanones become reasonably bulky. An eight-membered cyclic transition state model is proposed for this deprotonation reaction.

The pendant E-ring moiety of the podophyllotoxin aza-analogue 1 that is a potent inhibitor of microtubule assembly was modified in order to acquire inhibitory activity of DNA topoisomerase II. The monophenolic analogue 2 did not exhibit human topoisomerase II inhibition, while the ortho-quinone 3 that was obtained by oxidation of 2 inhibited its catalytic activity (decatenation) in a dose-dependent manner and stimulated double strand DNA breaks in supercoiled circular plasmid DNA, resulting in the production of linear DNA. These results showed that the topoisomerase II inhibition of the ortho-quinone 3 is due to stabilization of the topoisomerase II-DNA covalent binary complex. On the other hand, the ortho-quinone 3 did not inhibit the relaxation process of supercoiled DNA by topoisomerase I at concentrations up to 400 microM, nor was intercalation observed in unwinding measurements of 3. Therefore, the ortho-quinone 3 was shown to be a novel nonintercalative topoisomerase II specific inhibitor that stabilizes the cleavable complex. The present results suggest that the 4'-free hydroxyl group on the E-ring and the sugar moiety on the C-ring are not a prerequisite for topoisomerase II inhibition by podophyllotoxin derivatives.

Enantioselective deprotonation of 4-tert-butylcyclohexanone was examined using 1-phenylethylamine- and 1-(1-naphthyl)ethylamine-derived chiral lithium amides having an alkyl or a fluoroalkyl substituent at the amide nitrogen. The lithium amides having a 2,2,2-trifluoroethyl group on the amide nitrogen are easily accessible in both enantiomeric forms, and were found to induce good enantioselectivity in the present reaction.

Catalytic protonation of achiral lithium enolates (derived from 2-substituted-1-tetralones), mediated by a chiral tetraamine ligand [( R , R )- N , N ′-bis[1-phenyl-2-(1-piperidinyl)ethyl]-1,3-propanediamine (0.10 equiv.)], was achieved with high enantioselectivity (up to 93% ee) by using water (10% aqueous citric acid) as a proton source. A possible mechanism of highly efficient catalytic turnover of the chiral tetraamine ligand is discussed.

Catalytic asymmetric alkylation of achiral lithium enolates of 1-tetralone and cyclohexanone with reactive alkyl halides was realized by using a combination of a chiral tetradentate amine (∼0.05 equiv.) and an achiral bidentate amine (2 equiv.).

The rate of the reaction of the lithium enolate of 1-tetralone with alkyl halides was enhanced greatly in the presence of 3 equivalents of 1,1,4,7,10,10-hexamethyltriethylenetramine. The ratio of the monoalkylated product to the dialkylated product was found to have increased under a shorter reaction time.

The 1,4-addition reaction of organolithium reagents with 2,6-bis( tert -butyl)-4-methoxyphenyl naphthalenecarboxylates gave regioselectively substituted dihydronaphthalenecarboxylates in high yields. Successive treatment of the esters with organolithiums in THF, lithium triethylborohydride, methyl iodide, and finally sodium borohydride in methanol, provided regio- and stereoselectively the corresponding 1,1,2- and 1,2,2-trisubstituted dihydronaphthalenylmethanols in good yields. This one-flask process is constituted from a sequence of five reactions involving a reductive generation of an aldehyde metal enolate from a ketene as the key step.

Enantioselective asymmetric alkylation of achiral lithium enolates mediated by chiral tetradentate amine ligands is achieved to give chiral quaternary carbon centers. Turnover of a chiral tetradentate amine in the presence of an achiral bidentate amine during the reaction is also realized.

A highly efficient process of aerobic oxidative coupling of 2-naphthol derivatives catalyzed by 1 mol % of Cu(OH)Cl·TMEDA has been developed. Enantioselective oxidative coupling of naphthols was achieved by the use of 10 mol % of chiral catalysts prepared from proline-derived diamines and cuprous chloride, affording the corresponding binaphthols in good enantioselectivities of up to 78% ee. The ester moiety at the 3-position of the substrate was found to be essential for the good asymmetric induction observed in the present coupling reaction.