In this study, we focus on nanoscale copper-rich precipitates and attempt to elucidate their effect on the embrittlement of reactor pressure vessel steels. Our final goal is to evaluate such embrittlement from a microscopic viewpoint on the basis of an atomistic simulation. We develop a multi vacancy lattice Monte Carlo (MVLMC) method that can analyze a model having more than one vacancy. We show that the process of copper clustering consists of two phases-the formation phase and the combination phase. Further, we carry out a detailed analysis of the combination process of a cluster using MVLMC and evaluate the formation mechanism of a cluster using the distance between clusters. We find that when a nanocluster smaller than 1 nm and a cluster of approximately 2 nm coalesce, minute nanoclusters separate from the former cluster and are absorbed by the latter cluster.
A parameter set for Buckingham-type potentials to describe interatomic bonding between Na+-O2-, Co3+-O2-, Co4+-O2-, and O2--O2- in NaXCoO2 thermoelectric materials having a high figure of merit was determined by ab-initio calculations. Parameters for pairs other than O2--O2- were chosen so that they reproduce the lattice constants and elastic constants of NaCoO2 obtained by ab-initio calculations. Fitting was also performed using the corresponding binary oxides as well as NaXCoO2 in order to improve transferability and accuracy. Lattice constants calculated using the potential were in good agreement those of the binary oxides and the reproducibility of elastic constants was also satisfactory. The potential is robust enough to simulate atomic vibrations in molecular dynamics even at elevated temperatures. In-plane phonon thermal conductivities calculated by perturbed molecular dynamics with the potential are in good agreement with experimental values and the reduction of the thermal conductivity with increasing temperature due to phonon-phonon scattering is also reproduced well. Molecular dynamics simulations with this potential set enable features unobservable by experiment to be revealed, such as Co valence distribution at elevated temperature.
Effects of segregation of solute atoms and vacancies on migration of antiphase boundaries (APBs) in Fe3Al with slightly off-stoichirometric (Fe-24 and 26Al) compositions (unit: at%) at 673 K have been studied by a phase-field method in which local vacancy concentration is taken into account [Koizumi et al. Acta Mater 2008;56:5861, ibid. 2009;57:3039], and results were compared to those for stoichiometric and far Al-rich compositions obtained in the previous study. Shrinking of circular APBs having different phase-shift vectors of a/4<111> and a/2<100> (B2-APB and D03-APB, respectively) were simulated and their boundary mobilities were evaluated. Similar effects of the segregation on the migration of B2-APBs were observed for all the compositions, that is, vacancies segregated and Al-atoms were depleted at B2-APBs. Vacancy concentration at B2-APBs was up to 80 % higher than that in the bulk, which enhanced the migration of B2-APBs greatly. In contrast, the segregation to D03-APBs exhibited a marked composition dependence. Vacancies are depleted and Al-atoms segregated at D03-APBs in Fe-28Al, whereas vacancies segregated and Al-atoms were depleted at D03-APB in Fe-24Al and Fe-25Al. Almost no segregation was observed in Fe-26Al. Solute-drags suppressed the migration of D03-APBs in Fe-24Al and in Fe-28Al, and the breakaway of APBs from their segregation atmosphere increased their boundary mobilities by almost one order of magnitude.
We performed first-principles theoretical calculations to investigate systematically the solution stability of rare-earth elements (REs), i.e., Sm, Gd, Dy and Er, doped in the perovskite oxide BaTiO3 in various phase conditions and chemical compositions, in order to clarify the dependence of the fabrication condition on the selectivity of the substitution site. We found that Gd, Dy and Er occupy both the Ba and Ti sites and that only Sm tends to occupy the Ba site. However, the substitution of Sm at the Ti site occurs under the condition of oxidative atmosphere and Ba-rich composition. Further, we also examined the interaction between REs and the O vacancies in BaTiO3. The mechanism for suppressing the migration of O vacancies by REs is discussed.
It is generally accepted that under ordinary conditions adopted for the study of metal-hydrogen (M-H) compounds: a) hydrogen can be described reasonably well as an ideal gas, b) the distribution of hydrogen atoms over the different sites of the lattice can be expressed by the Fermi-Dirac statistics, c) the average hydrogen-hydrogen interaction energy which is a function of the number of H-atoms in the lattice includes all the contributions coming from the electrons and the lattice. By considering all the above approximations we have derived a relation between the pressure of gaseous hydrogen and the number of hydrogen atoms in the bulk. The PCIs were obtained by calculating the standard chemical potential for an ideal gas from statistical mechanics and optimizing the other free parameters from the experimental PCIs data at one temperature. We were able to closely predict the PCIs at other temperatures when they were compared with the experimentally obtained PCIs for various RNi5-type hydrogen storage materials.
We investigated substrate specificities of farnesyl diphosphate synthases (FPSs) derived from porcine liver and Bacillus stearothermophilus by examining the reactivity of cyclopentylideneethyl diphosphate with several 3-alkyl homologs of isopentenyl diphosphate. Reaction of cyclopentylideneethyl diphosphate with isopentenyl diphosphate using porcine liver or bacterial enzyme gave 10-cyclopentyliden-3,7-dimethyldeca-2,6-dinenyl diphosphate as a double condensation product, with relative yields of 40.9% for the porcine liver enzyme and 15.9% for the bacterial enzyme. Reaction of cyclohexlideneethyl diphosphate with 3-ethylbut-3-enyl diphosphate using the bacterial enzyme gave 10-cyclohexliden-3,7-diethyldeca-2,6-dinenyl diphosphate (yield: 24.6%).
Polydimethylsiloxane and poly(ethylene oxide) randomly grafted polyamide (PA-g-SE) and poly(amide-imide) (PAI-g-SE) were prepared by a macromonomer method, and the effect of the backbone structure on the thermal property and the solubility of the graft copolymers was investigated. Glass transition temperature (Tg) of PAI-g-SE was observed in the range of 160 - 170°C, whereas Tg of PA-g-SE was not observed in the range of 0 - 300°C. The obtained PAI-g-SE was soluble in some solvents such as DMSO, DMF, THF and chloroform, whereas PA-g-SE was soluble only in NMP just after precipitation when it was swollen in methanol. In addition, the solubility of PAI-g-SE was depended on the components, where the affinity of polymer against THF and chloroform increased with the increase of PDMS content in the polymer.
Polydimethylsiloxane (PDMS) grafted polyimides with different backbone structures were prepared by polycondensation of 3,5-bis(4-aminophenoxy)benzyloxypropyl-terminated PDMS with 4,4’-oxydiphtalic dianhydride (ODPA) and 4,4’-hexafluoroisopropylidene diphthalic anhydride (6FDA) followed by chemical imidization to afford PI-g-PDMS and FPI-g-PDMS, respectively. Another PDMS-grafted polyimide, MPI-g-PDMS, was also prepared by similar procedure from 3,5-bis(4-amino-3-methylphenoxy)benzyloxypropyl-terminated PDMS and ODPA. 1H-NMR and FT-IR spectra clearly demonstrated that the desired PDMS-grafted polyimides were successfully synthesized. FPI-g-PDMS and MPI-g-PDMS exhibited the high solubility, which were soluble in chloroform, THF, DMF, NMP, toluene, benzene as well as acetone, while PI-g-PDMS was soluble only in chloroform. Therefore, the membranes could be prepared by solvent-casting method using chloroform. Interestingly, the obtained membranes became insoluble in any solvents after the thermal imidization at 200℃ in vacuo for 24 h.
Gas transport properties (i.e., permeability, diffusivity, and solubility) and the crystallinity/crystalline structure of poly(lactic acid) (PLA) membranes were systematically investigated. PLA membranes with different crystalline structures were prepared by regulating the heating and cooling conditions during their membrane preparation. The PLA membrane that was thermally-treated at 70°C was amorphous, while the membrane heated at higher than 80°C had crystalline structures. As the treatment temperature increased, the crystallinity increased and the PLA crystal growth branched out in a radial fashion. Regardless of crystallinity, the order of the gas permeability, diffusion, and solubility coefficients was the same for all membranes; permeability coefficient: H2>CO2>O2>N2>CH4; diffusion coefficient: H2>O2>N2>CO2>CH4; solubility coefficient: CO2>CH4>O2>N2>H2. Interestingly, unlike common crystalline polymer membranes, the permeability coefficient in a crystalline PLA membrane was larger than that in an amorphous PLA membrane. The gas permselectivity in the amorphous and crystalline PLA membranes was larger than 120 for H2/N2, 6 for O2/N2, 23 for CO2/N2, and 27 for CO2/CH4 and less than 1 for CH4/N2.
Diluted magnetic semiconductor of transition metal doped Cu2O has been studied to realize the new room temperature ferromagnetic materials for the spintronics devises. Commercial TM oxides and Cu2O. were used as the precursors which were mechanically milled by the planetary ball mill with WC vial and balls at 0～700 rpm for 15 minutes. Only vanadium was successfully doped into Cu2O. These V-doped samples showed weakly ferromagnetic properties at room temperature.
Room temperature ferromagnetism of GaN powder with vacancies was realized by the mechanical milling method, where the GaN powder was milled by WC balls at 0～700 rpm for 15 minutes. The grain size of GaN powder was reduced to below 10 nm by the milling above 200 rpm. The crystal structure of milled powder kept a wurtzite-type hexagonal one. Enhancement of magnetization M at 200 rpm is considered to be due to the formation of vacancies. On the other hand, the rapid increase of M at 600 rpm corresponded to the discontinuity expansion of lattice parameter a by the overproduction of vacancies.
We report the real-time and noninvasive detection of K+ release through cell membrane using a biologically-coupled field effect transistor (bio-FET). To achieve this purpose, the cell/transistor interface, which can selectively detect K+ release through the ion-channel, was developed. The K+ release through the ion-channel caused by apoptosis (programmed cell death) could be electrically detected using the bio-FET with crown ether monolayer. Thus we have demonstrated the ability to analyze selectively the ion channel behavior using the bio-FET modified with the functional monolayer.
The electrophoretic mobilities (EPMs) of various leukocytes of mouse origin were measured using microcapillary electrophoresis (µCE) chips. The average EPMs of acute lymphoblastic leukemia (L1210), myeloma (PAI), myeloid leukemia (M1), and myelomonocytic leukemic (WEHI3) cell lines were −0.83×10−4, −1.0×10−4, −1.5×10−4, and −1.2×10−4 cm2 V-1 s-1, respectively. The average EPMs of mouse primary blood leukocytes, bone marrow cells, and splenic cells were −2.0×10−4, −1.6×10−4, and −1.3×10−4 cm2 V-1 s-1, respectively. EPM was different for each type of leukocyte. These quantitative data concerning cell surface charge are useful fundamental knowledge for understanding the interactions between cells and biomaterials, and for designing biomaterials.
This article reports the feasibility study to explore the application of cell electrophoretic mobility (EPM) as a biomarker for monitoring the progress of stem cell differentiation. The EPM of human mesenchymal stem cells (hMSCs) was measured using an on-chip cell electrophoresis system before and after osteogenic differentiation. The EPM of undifferentiated cells was widely dispersed and followed a trapezoidal-like distribution. After inducing differentiation, the EPM changed gradually into a bell-shaped distribution. It was noteworthy that the interquartile range (IQR) gradually became narrower with the progress of differentiation: −0.61×10−4 to −1.10×10−4, −0.89×10−4 to −1.19×10−4, and −0.64×10−4 to −0.81×10−4 cm2 V−1 s−1 at 0, 7, and 21 days, respectively, after the initiation of differentiation. Thus the heterogeneity of the cell populations decreased with the progress of differentiation. The result appears to reflect the fact that differentiation into specific lineages is the process by which stem cell lose their built-in variability, which is the basis of their multipotency.
Carbon materials were formed from coffee wastes by gas activation process using microwave heating for rapid production, and this material showed cell geometry and micro pores at cell surface. The relationship between the pore characteristics of these materials and the activation conditions were studied. A 2.45 GHz microwave controlled at 100 W irradiated the coffee wastes for carbonization during 105 min, and the gas activation process performed by microwave power varied from 100 to 500 W with Ar and gas mixture of Ar and CO2. N2 adsorption isotherm profiles at 77 K indicated the Langmuir type profile. The specific surface area and the micro-pore volume reached to 357 m2/g and 16.5×10-2 cm3/g at 490 W microwave power with the gas mixtures, respectively. Structure of carbon material clearly reveals cell geometry. The averages of the cell partition wall thickness decreased as the specific surface area and the micro-pore volume increased. These results suggest that the cell geometry and pore characteristics of carbon materials can be controlled by microwave power.
Gold nanoparticles are expected as new materials for optical devices owing to their size-related properties. However, the typical gold nanoparticles surrounded by long-chain alkane thiols 1 (ligand molecules) are not tolerant of heating process because the interactions between the ligand molecules are not strong enough. In order to develop thermally-resistant gold nanoparticles, the authors focus on the functional groups which can form strong interactions between the ligand molecules such as hydrogen bonding and π-π stacking. In this study, 6 types of ligand molecules were synthesized and the thermal stability of the corresponding gold nanoparticles was evaluated by thermo gravimetry (TG) and differential scanning calorimetry (DSC). And, it was found that the thermal stability highly depended on the chemical structure of the ligand molecules. Since the amide group and the tolyl group which were introduced into the ligands had the ability to form intermolecular hydrogen bonding and π-π stacking, respectively. Therefore, the gold nanoparticle surrounded by amide-tolyl type ligand 3b was considered to be most thermally stable owing to the strong interactions between the functional groups.
We have investigated the conductance of a single 1,3-benzenediamine or 1,4-benzenediamine molecule bridging between Au electrodes, in order to discuss the effect of the end group position on the conductance of the single disubstituted benzene molecular junction. The conductance of the single 1,3-benzenediamine molecular junction was determined to be 5×10-3 (±1×10-3) G0 (G0=2e2/h). This conductance value was smaller than the previously reported conductance value of the 1,4-benzenediamine single molecular junction (0.01 G0) measured under the same experimental condition by a factor of two. The contribution of the quantum interference effect on conductance of the single benzenediamine molecular junction was discussed. In the single 1,3-benzenediamine molecular junction, two electron paths around the benzene ring would interfere destructively due to the difference in the path length, leading to a decrease in conductance of the single molecular junction.
Highly Surface-enhanced Raman Scattering (SERS) active Ag dimer array was prepared to investigate the orientation of molecules in an anisotropic electromagnetic field. The system allow us to observe very clear time-dependent change in the SERS spectra of 4,4'-bipyridine adsorbed in water. The SERS spectra showed several characteristic features especially in the change of relative intensity of the bands. The characteristics were compared with those of the calculated Raman spectra with distinct irradiation polarization. The analysis indicates that the spectra reflect the orientation of molecules. The 2D cross correlation analysis further prove that the present observation provide the information on the dynamics of a small number of molecules in the highly localized anisotropic electromagnetic field at the nano-gap of the Ag dimer
We have characterized molecular filtering behavior of two lipid molecules labeled with BODIPY derivatives. The difference of the structure is the functional group at the end of alkyl chain; methyl and thienyl. First, the filtering behavior for these two molecules was examined independently using the system of spreading bilayer through the metal nano-gate. By the fluorescence microscope observation, it was found that the molecule with thienyl was filtered more effectively. The filtering efficiency per nano-gate was about 9 % and 2 % for the molecule with thienyl and methyl, respectively. When these two molecules were incorporated in the self-spreading lipid bilayer, they were found to act as energy donor (methyl) and acceptor (thienyl), which resulted in the appearance of fluorescence resonant energy transfer (FRET). The FRET spectrum showed that the fluorescence intensity ratio of acceptor to donor continuously decreased during spreading through nano-gates. Judging from the result that the FRET efficiency is highly sensitive to not only dye concentration but also the molecular orientation or viscosity of the spreading bilayer, we conclude that the origin of the filtering efficiency can be discussed by monitoring the acceptor/donor intensity ratio in the bi-analyte incorporated system.
ABA triblock copolymer comprised of poly (L-leucine) as the A segment and polyethylene glycol as the B segment was prepared by ring opening polymerisation of N-carboxyanhydride of L-leucine using the amine-terminated poly(ethylene glycol) as an initiator. Melting temperature for the gels prepared through the solution of the copolymer and chloroform was observed by inverting the test tube. The results of observation were interpreted in terms of Eldridge-Ferry plot.
A novel hydrogel has been fabricated using vinyl modified polyrotaxane as a cross-linker. A sparsely dispersed propylene oxide modified α-cyclodextrins which were threaded into the long polyethylene glycol (Mw = 35000) and were trapped by bulky 1-adamantanamine molecules was used as a hydrophilic polyrotaxane, HPR. HPR was modified by a small amount 2-acryloyloxyethylisocyanate monomer to obtain a water soluble polyrotaxane-based movable cross-linker, MHPR. Polymer gels, prepared by free radical polymerization of thermo-sensitive monomer N-isopropylacrylamide (NIPA) in presence of MHPR cross-linker, gave transparent, soft and flexible, mechanically strong and fast thermo-sensitive gels. The gel changes its volume isotropically and reaches rapidly to the equilibrium shrunken state after a temperature jump. The hydrophilicity of the cross-linker retains the homogeneity in the gel network and restricts the formation of aggregated globules, which permits the poly(NIPA) chains along with macrocycles to move or rotate freely inside the gel networks under deformation. The movability of the cross-links can strongly minimize their localized stress during deformation. The fascinating characteristics of the gel was compared and contrasted with the gels prepared using using hydrophobic polyrotaxane-based multifunctional and bi-functional N,N’-methylene-bis-acrylamide cross-linkers.
The dynamics of dialysis-induced chitosan gel formation has been analyzed by a theory with “moving boundary picture” for the case where the gelation occurs by neutralization. Three datasets for the dependence of concentrations of NaOH in the immersing solution, acetic acid in the solvent and chitosan for the whole range of time fit well to the theoretical equations, by which the validity of the theory was confirmed.
In recent times, a “crystalline” and flexible optical waveguide candidate with excellent heat-resistance and dimensional stability are developed. For the practical use of this crystalline optical film in the near future, an accurate control of the solid-state structure is indispensable because of the necessity of reducing light refraction at the crystalline/amorphous interface. In the present study, changes in the fine structure and lamella arrangement upon drawing poly[tetrafluoroethylene-co-(perfluoroethylvinylether)] (abbrev. EFA) transparent crystalline films are investigated by using wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) methods. The EFA is crystallized as a lamella crystal in the films and forms a thicker lamella. Upon the drawing of the EFA films, four-point SAXS diagrams develop in the photograph at through direction to the film, which implied that a particular type of layer structure, an alternately tilted lamella arrangement known as the herringbone, is formed. From the result of WAXD and SAXS measurements at edge direction to the film, it is found that formation of isotropic disordered lamella arrangement. Therefore, it is indicated that three dimensional lamella arrangement in this fluorinated transparent film forms uniaxially cylindrical symmetry.
We investigated the solid-state structure and formation of organized molecular films for newly synthesized aromatic polyamides having both a rigid main-chain and a flexible side-chain with different lengths by wide angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS), and surface pressure-area (π–A) isotherm measurements. The solid-state structure of poly-(N-methylbenzamide) (PABA1) belonged to the monoclinic system, whereas PABA3, PABA4, and PABA5 showed an orthorhombic packing system. PABA7 and PABA8 formed amorphous polymers. In the case of PABA17, a two-dimensional hexagonal lattice was formed as a sub-cell consisting of side chains. These polymer monolayers were highly condensed on a water surface at 15 °C. From these experimental findings, it is concluded that the polymer synthesis method employed in this study can be directly used to control the crystalline morphology (the third order structure of polymers) of polymer monolayers.
We have developed a highly stable, layered structure for ternary copolymers in Langmuir-Blodgett (LB) films, with substantial durability over the long term. In these ternary copolymer LB films, amorphous side-chains support the layered structure, and the distance between the layers is controlled at the nanometer scale by the composition of hydrogenated and fluorinated side-chains. In the present study, we investigated the molecular orientation of organized molecular films with regard to solid-state structure of newly synthesized ternary comb copolymers with a carbazole ring by surface pressure-area isotherms, in-plane and out-of plane X-ray diffraction, and atomic force microscopy. Structural features of LB film of ternary copolymers may result from enhancement of π-π interactions between the arranged carbazole rings. The side-chains of the copolymers in the two-dimensional films are apparently in a miscible state, and monolayers form a homogeneous amorphous surface because of cancellation of differences in van der Waals forces between the two types of side-chains. As a result, new polymer nanomaterial expected to form a highly ordered layer structure having substantial durability over the long term is proposed because amorphous side-chains support the layer structure in the LB multilayers.
We investigated the molecular arrangement and surface morphology of organized molecular films with regard to solid-state structures for newly synthesized aromatic polyamides with various side chain length by surface pressure-area (π–A) isotherm, in-plane and out-of plane X-ray diffraction (XRD), and atomic force microscopy (AFM). Since the aromatic polyamides have rigid main chain and flexible side chain, it may be possible to form the phase separated structure at sub-nanometer scales. These polyamides form the extremely condensed monolayer on the water surface. Multilayers of these polyamides transferred by Langmuir-Blodgett (LB) method construct highly order layer structure. On the other hand, in the two-dimensional film plane of polyamides, amorphous structure of side chains is formed except for octadecyl derivatives. Changes in the surface morphology of monolayers for these polyamides definitely depend on the side chain length. Spherulitic, fibril like, and homogeneous flat morphologies of the film surface are systematically observed by AFM measurement.
The molecular arrangement and surface morphology of organized molecular films of alkylammonium-M bis(1, 3-dithiole-2-thione-4, 5-dithiolate) ((dmit)2, M = Ni, Au, and Pd) charge-transfer complexes were investigated by using the surface pressure-area isotherm, in-plane and out-of plane X-ray diffractions (XRD), and atomic force microscopy. In the bulk state, several alkylammonium-M(dmit)2 molecules could not form a highly ordered layer structure along the c-axis and a sub-cell structure of the alkyl chain in the ab-plane; however, almost all molecules formed a layer structure in the film multilayers. Monolayers of alkylammonium-M(dmit)2 salts on the water surface were relatively condensed. Out-of plane and in-plane XRD measurements revealed that over a long period, systematic changes occurred in the two-dimensional lattice of alkylammonium-M(dmit)2 salts and not in their bulk state. These structural changes appear to be caused by enhancement of the van der Waals interaction among long hydrocarbons and the π-π interaction among M(dmit)2 units arranged two-dimensionally. In addition, both the molecular arrangement and the morphology of the films showed dependence on the hydrocarbon length, number of alkyl chains, and kind of central metal. In particular, the molecular arrangement of materials having didecyl chains changed drastically and M(dmit)2 units were highly oriented in the ab-plane.
As a method for characterizing the electronic state and molecular orientation of organic materials put on electrodes, infrared reflection-absorption spectroscopy (IR-RAS) is a well-known powerful tool. We have demonstrated that transparent electrodes based on zinc oxide are useful as substrates for the IR-RAS measurements. Although their absorption-signal enhancement effect is smaller than that of gold substrates, sometimes IR-RAS with them provides a better basis than that with gold for discussing the molecular orientation.
Integration of organic and inorganic material is a promising method for obtaining unusual functional material. It has been investigated that a hybrid system of oxidative enzyme and Prussian blue (PB, FeⅢ4[FeⅡ(CN)6]3) provides an amperometric biosensor working at a very low potential range (0.0 V vs. Ag/AgCl) due to the catalytic function of PB. Recently, we developed a new fabrication method through a combination of Langmuir-Blodgett (LB) technique and self-assembled monolayers (SAMs) technique. In this method, an enzyme of glucose oxidase was chemically bonded with -COOH terminal group of SAM, after that, PB nano-clusters were electrostatically immobilized in the octadecyltrimethylammonium LB film. For the glucose biosensor prepared with this method, we observed a clear response current generation depending on the glucose concentration at a low potential range, a stable linear relationship between the glucose concentration and output current, and a high stability of the sensor performance.
Molecular arrangement and morphology of Langmuir-Blodgett (LB) films for the several organo-modified montmorillonites were investigated by out-of plane and in-plane X-ray diffraction (XRD), and atomic force microscopy (AFM). These organo-modified montmorillonites are formed by cation exchange reaction with quaternary ammonium regents containing octadecyl chain. The organo-modified montmorillonites formed extremely condensed monolayer on the water surface estimated by surface pressure-area (π-Α) isotherms. From the results of out-of plane XRD, formation of highly ordered layer structure was confirmed in these clay LB film. Further, two-dimensional lattice of long alkyl chain of organo-modified parts packed hexagonally or orthorhombically in the films. Surface morphology of Z-type monolayers on solid of organo-modified montmorillonites indicates heterogeneous modification ratio in montmorillonite surface by tapping mode AFM observation.
Monolayer behavior on the water surface and mesoscopic morphological formation on solid of mixed organized moelcuar films of organo-modified montmorillonite and poly-(L-lactide) (abbrev. PLLA) were investigated by surface pressure-area (π-A) isotherm and atomic force microscopy (AFM). From the results of π-A isotherm of neat PLLA monolayer, clearly phase transition behavior from monolayer to crystal was confirmed with plateau at low surface pressure region. Straight chain-type polymer may form the lamellae like three-dimensional structure at transition point although this type transition behavior generally corresponds to a collapse of monolayer and formation of piled up film. In the case of mixed monolayer with organo-modified montmorillonite, this transition point is independent on the mixed ratio, and indicates almost constant value in their isotherms. That is to say, this is immiscible system. From the result of AFM observation, phase separated structure was confirmed in mesoscopic scales. This phase separated morphology remarkably varied with mixed ratio.
In this study, self-assembled arrays of silica particles were formed on the two-dimensional patterns of the functionalized templates fabricated from phase-separated mixed Langmuir-Blodgett films. Immersion of the functionalized templates into silica particle dispersion led to the formation of silica particle arrays due to the electrostatic interaction between the dissociated carboxylic groups originating from bovine serum albumin on the silica particles and the amino groups on the functionalized templates.
For field effect transistor using single-walled carbon nanotubes (SWNTs) with extremely dense packed electronic devices, diameter, alignment, and chirality of the SWNTs should be controlled. We propose a novel technique to grow the selective SWNTs with specific chirality using free electron laser (FEL) irradiation during growth. The Co/Mo catalyst was used for alcohol catalytic chemical vapor deposition (ACCVD). From the results of Raman spectra, both of conductive and semiconductive SWNTs grew without FEL irradiation. With 800 nm FEL irradiation during growth, only semiconductive SWNTs grew, the chirality of which was expected to be (14,0), (10,6), (9,7), (11,4), (10,5) with approximately 1.1 nm in the diameter. The number of possible chirality of ACCVD grown SWNTs with FEL irradiation was much reduced to 5 from 18.
Soluble wool keratin was prepared by derivatization of disulfide (SS) bonds of cystine residues to carboxymethyl alanyl disulfide (CMAD) groups using thioglycolic acid (TGA). The solubilization reaction was carried out in 0.2M TGA aqueous solution at 30°C for 1 to 24 h under alkaline conditions (pH = 11-13). The yield increased with increase of pH and reaction time. However, the yield decreased when soluble wool keratin was prepared in pH = 13.0 systems for 24 h. Electrophoresis patterns of soluble wool keratin were similar to that of raw wool regardless of reaction time. However, electrophoresis pattern of soluble wool keratin prepared in pH = 13.0 systems for 24 h tended to smear at high molecular weight region. Fourier transform infrared (FT-IR) spectra of soluble wool keratin showed absorption of the associated carboxylic acid due to CMAD groups. Regenerated wool keratin films were prepared from soluble wool keratin by the solution casting method. FT-IR spectra of film were similar to that of raw wool. Thermogravimetry-differential thermal analysis (TG-DTA) revealed a higher thermal stability of films and regeneration of SS bonds between keratin molecules in the films. Flexible films were obtained by addition of glycerol. The elongation of films significantly increased with increase of glycerol content.
Diethylenetriaminepentaacetic acid (H5dtpa) was allowed to react individually with five lanthanide (Ln) oxides of La2O3, Eu2O3, Gd2O3, Ho2O3, and Er2O3 at a molar ratio (Ln:H5dtpa) of 5.1:3.0 in water. The composition of the resulting pentanuclear complexes was estimated on the basis of elemental analysis data. Thus, the chemical reaction has been written as 5 Ln2O3 + 6 H5dtpa → 2 Ln5(dtpa)3 + 15 H2O. The complexes were characterized by Fourier-transform infrared and ultraviolet–visible spectroscopy, X-ray diffraction, and pH measurements. The infrared spectra showed a high probability of a bridged COO– structure. For three absorption bands in the range of 360–460 cm-1, the absorption maximum wavenumber was plotted as a function of the effective ionic radius (for a coordination number of 8) of the Ln(III) ions. The linear plots are probably related to Ln–O or Ln–N bonding. As expected, the 4f electrons of the Ln(III) ions did not play a role in the bonding between the central metal and its ligands. The nonparticipation of these electrons is a requirement for MRI contrast-enhancing agents.
In order to improve the performance of actuator using shape memory alloy, we studied the effects of aging-treatment on transformation temperature difference and temperature hysteresis of Ti-Ni-Cu shape memory alloy. The chemical composition of specimen is Ti-41.7Ni-8.5Cu (at%) and cold working ratio (CW) is 10% and 40%. Aging temperature is 673K, and aging time is varied from 3.6ks to 1800ks. In the case of CW=10%, the transformation temperatures have a little dependence on aging time. However, in the case of CW=40%, As and Mf increase with increasing of aging time. This difference is caused by the variation of dislocation density by aging and the difference of sensitivity to dislocation density of each transformation temperature. Moreover, the temperature response (Af -As) of CW=40% increases with increasing aging time.
The phase transformation behavior of polycrystalline shape memory alloys is investigated by a constitutive model under multi-axial stress states of tension and shear. The constitutive model used here was developed by the authors to describe the accommodation mechanism acting on the phase transformation phenomenon. The transformation occurs in microscopic transformation systems of crystals and is calculated by the constitutive model. The transformation stress is introduced here as an indicator to describe the macroscopic transformation start. Transformation stresses are obtained from calculated stress-strain curves for various loading paths. The interaction surface of macroscopic transformation stresses obtained is revealed to be very similar to the Mises yield surface in the stress space. Discussions are also made on the relation between the equivalent stress and the equivalent transformation strain of Mises type.
To investigate the effect of cold working ratio on function deterioration process of Ti-Ni shape memory alloy, repeated loading-unloading tests with constant strain condition were carried out. The chemical composition of specimen is Ti-50.3at%Ni and cold working ratio (CW) is 30.1 % 43.0 % and 51.0 %. Heat-treatment condition is at 673 K for 3.6 ks. The decrement of recovery strain decreases with increasing CW. Moreover, lower CW leads to the decreasing of the number of loading-unloading cycle which decrement of recovery strain slowdown starts. Furthermore, decrement of maximum applied stress decreases with increasing CW. On the other hand, in spite of critical stress for inducing martensite increases with increasing CW, the decrement of critical stress for inducing martensite is almost same regardless of CW. From these results, increasing of CW leads increasing of deterioration resistance. These tendencies are caused by the variation of dislocation density and grain size due to the variation of CW.
Carbon nanotubes (CNTs) are a promising new material for electrodes of supercapacitors, owing to their unique internal structure, high surface area, remarkable chemical stability, and electrical conductivity. In this study, CNTs films with nanoporous structure were made by a filtration method. A nanostructured manganese dioxide layer was electrodeposited on a thin CNT film to form a flexible CNT/MnO2 film electrode for supercapacitors. The morphology of the CNT/MnO2 electrode was examined by SEM and TEM. Compared with a pure CNT film, the CNT/MnO2 electrode shows a higher specific capacitance. The CNT network in the CNT/MnO2 electrode acted as a substrate of good conductivity and high surface area. The nanostructured MnO2 not only increased the surface area, but also has enhanced reactions with the cations in the electrolyte to increase specific capacitance.
The influence of MgO powder addition up to 5 mass% on thermal decomposition of Mg(OH)2 from 380℃ to 420℃ was examined, and it was revealed that the content of MgO generated from Mg(OH)2 greatly increased with the addition of MgO, compared with that in Mg(OH)2 without addition of MgO at 400℃. The microscopic growth behavior of MgO crystal due to added MgO powder has been studied to clear the cause of promotion.
In Japan, large amount of waste gypsum board is generated from demolition works, and most of it has placed in the landfill. Many companies in Japan have attempted to recycle waste gypsum board to solidification treatment of waste slurry from construction works. However, some waste gypsum board contains fluoride and some chemical impurities. These impurities in the waste gypsum have possibility of soil pollution. Calcium hydrogen phosphate dihydrate (DCPD) reacts with fluoride in the aqueous solution and forms fluoroapatite (FAp). We have applied the reaction to immobilize fluoride in the environment. In this study, we have investigated immobilization of fluoride in waste gypsum by using DCPD, and apply the recycle gypsum to solidification of waste slurry. DCPD controlled release of fluoride from waste slurry less than 0.8 mg/L (Japanese environmental regulation of soil pollution). To improve reaction rate of DCPD, we attempted to surface modification of DCPD particles. By mixing DCPD with warm water, nano-scale particle formed on surface of DCPD particles. The surface-modified DCPD (“nano-etching DCPD”) reacted fluoride with high reaction rate and immobilized fluoride in waste gypsum effectively.
Birnessite-type K0.33MnO2 was prepared by the solid state reaction of KOH and MnCO3 in air. The XRD pattern of the sample calcined at 700°C can be indexed as a single phase of the monoclinic C2/m phase (a= 5.186Å, b = 2.851Å, c =7.154Å, β=101.74°). Their m zone ED patterns show superlattice spots indicating in-plane pseudo-hexagonal (√3×√3)h-R30° and monoclinic (3×1)m ordering. However, the lattice images do not show clear contrast of the superlattice. Although the m and m-zone ED patterns also showed clear superlattice spots, they show diffuse streaks due to the stacking disorder. The lattice images clearly revealed the details of the layer stacking. The thickness of the layers with the regular stacking is limited to several nano-meters because of the stacking disorder.
The duration of gas evacuation before the introduction of discharge gases into the panel is one of the major problems in the production of plasma display panels (PDPs). In this study, the outgassing characteristics during the panel evacuation stage were investigated by Kelvin probe force microscopy (KPFM). The origin of the impurity gases was studied by measuring the outgassed species from each layer comprising a PDP. The dominant species observed during the evacuation of the panel were H2O and CO2, with water vapor being the most abundant species. When the outgassing characteristics of the panel were compared with those characteristics of the MgO layer of the panel, the material responsible for producing a greater amount of water vapor turned out to be the MgO layer. We prepared epitaxially grown MgO films on Si substrates by metallo-organic decomposition (MOD). The outgassing experiments on single panels also showed that the long outgassing time of a PDP is mostly due to the MgO layer. Therefore, to reduce the gas evacuation time, a controlled atmosphere appears to be required during the deposition of these materials and the storage of the resulting panels. The MgO layer was investigated by mapping the difference in the surface potential between MgO layers with and without H2O by KPFM.
Here, to assess substrate specificities of E-and Z-farnesyl diphosphate synthases from Bacillus stearothermophilus and Thermobifida fusca, we examined the reactivities of isopentenyl diphosphate homologs having an alkyl group at the 3-position. E- and Z-FPP synthase reactions of geranyl diphosphate (GPP) with 3-ethylisopentenyl diphosphate produced E- and Z-3-ethylfarnesyl diphosphates (yield: 70.8, and 11.3, respectively). The E-FPP synthase reaction of GPP with 3-propylisopentenyl diphosphate produced E-3-propylfarnesyl diphosphate (yield: 40.1) however, when reacting GPP with 3-propylisopentenyl diphosphate by Z-FPP synthase reaction, only trace product was acquired. Further, neither E- nor Z-FPP synthase reaction of GPP with 3-butylisopentanyl diphosphate produced any product.
LiFePO4 was synthesized by a microwave hydrothermal heating (MH) method. The particle size of the product prepared by the MH method is in the range from 200 to 300 µm. The LiFePO4 cathode materials thus obtained had a higher discharge capacity and better cycle performance than those of the LiFePO4 samples prepared by a conventional hydrothermal reaction.
Gd-doped ceria (GDC) films supported by NiO-GDC substrates were prepared by electrophoretic deposition followed by co-sintering and reduction of NiO into metallic Ni. The detailed chemical and microstructural features of the samples before and after the reduction treatment were investigated. Inhomogeneous microstructures including nano-sized domains and superstructure were observed, and their formation was enhanced due to the diffusion of Ni. It is suggested that the Ni diffusion and the formation of inhomogeneous microstructures can form a layer in the GDC film close to the film/substrate interface, which has relatively low conductivity.
Mechanical alloying of Ti45Zr38Ni17 powder mixture formed an amorphous phase, but subsequent annealing caused the formation of an icosahedral (I) quasicrystal phase with a small amount of the Ti2Ni-type crystal phase, so that two kinds of working electrodes, amorphous and quasicrystal ones, were produced and their electrochemical performances were compared. Discharge capacity of quasicrystal electrode was significantly higher than that of amorphous one at room temperature. In every electrode, however, a few charge/discharge cycles were needed to be activated. After charge/discharge cycles, quasicrystal phase was stable but the amorphous phase turned into a (Ti,Zr)H2 hydride particularly after 20th cycle. At a current density of 15mA/g, discharge capacities of both quasicrystal and amorphous electrodes became higher at charging temperature of 328K than those at room temperature. The maximum capacities for both electrodes at 328 K were obtained in the 1st cycle, different from those at room temperature. It was indicated that quasicrystal electrode had higher discharge capacity and cycle stability than amorphous one.
In dye-sensitized solar cells, the incident light passes through a glass substrate, FTO transparent conducting layer, and then a dye-adsorbed TiO2 layer. In this process, however, some amount of the light is reflected and/or scattered to be out of the electrode before being absorbed by a dye. In this study, we deposited a light condensable SnO2 or ZrO2 layer on the back of the working electrode to increase the haze ratio of the incident light. By controlling the haze ratio, the conversion efficiency of the cell was effectively enhanced as high as 7.6%.
Heat capacity measurements have been made on NbH0.80 at the temperature between 300 and 420 K by adiabatic calorimeter. The behavior of heat capacity for β - α' phase transition of NbH0.80 investigated first-order transition with narrow and triangular shape. Activation energy of β phase and pre-transition region for NbH0.80 determined Eact = 0.13 (eV) and Eact = 0.32 (eV), respectively.
Nanomaterials based on lanthanide oxide (Ln2O3) and multielement Ln2O3 are become increasingly an important materials in development of breakthrough technology in optoelectronics and biomedicine area. A range of Ln2O3 such as Y2O3, Gd2O3, Tb3O4, Eu2O3, with the different nanoforms of particle, rod, wire and tube have been synthesized in using the soft template method. The growth mechanism to the nanostructures could be curiously affected by solution-solid process, anisotropic crystal in corporate with hydrogen bond interaction and polymers conformation. The transformation process from Y2O3-rod to tube forms has found and investigated to control the synthesis. The crystal structures, size, shape of the Ln2O3 products have determined by XRD, FESEM, and TEM. The luminescence properties of a variety of the synthesized nanophosphors Y2O3: Eu,Tb; YVO4: Eu; Tb(OH)3; TbPO4; EuPO4 have been investigated toward to develop a fluorescent label in biomedicine research.