In this article it is reviewed on enigmatic electrical and magnetic properties of La(Ba)MnO3 thin films, useful for tunable microwave filters. As-grown films have well separated insulating to metallic (Tp) and paramagnetic to ferromagnetic (Tc) transition temperatures, which can be understood from the phase separation model. The film shows negative magnetoresistance (MR) caused by normal double exchange coupling effect, and positive MR which is interpreted by a magnetostriction effect. The phase separation is caused by crystal strain in the film. By annealing these two temperatures, Tp and Tc, become more separated, implying a size reduction of ferromagnetic grains. The phase separation scenario can be confirmed by ferromagnetic resonance (FMR) showing doublet signals. The FMR indicates anisotropic phase transition which supports the magnetostriction model. Moreover, the narrow FMR signals suggest high spin ordering and good crystallinity.
Recently, long coated conductors, in which superconducting YBa2Cu3O7 (YBCO) thin films are deposited on oriented metallic tapes, have been developed, and high critical current densities Jc are required for their application to various power devices. In this review we present our recent investigations on the flux pinning mechanisms in YBCO thin films that determines Jc.
Aiming at developing DLC coatings with not only their internal stress relaxed but also their adhesion improved, and their excellent mechanical properties such as high hardness, low friction coefficient, etc preserved at the same time, the deposition of Ti-containing DLC films by magnetron DC sputtering was examined using dual targets of titanium and carbon. The deposition of DLC films or Ti-containing DLC films were respectively carried out in the atmosphere of argon at the pressure of 0.4 Pa by sputtering of only a carbon target or by co-sputtering of both the carbon one and a titanium one. Both the DLC films and the Ti-containing DLC films obtained in this study looked dark brown and appeared to be semitransparent. According to Raman spectroscopy, a typical spectrum for DLC coatings was detected for the Ti-containing DLC films as well as for the DLC films. And it was found that the G band slightly shifted to higher wave numbers and the intensity of the D band was enhanced by co-sputtering, compared to the spectrum for the DLC films. Furthermore, based on both the indentation hardness and the electrical resistivity of the obtained films, it was found that some Ti-containing DLC films could have high hardness such as Si-wafer and could also have 100 times lower electrical resistivity than that of DLC films, at the same time.
Tubes are often required to exhibit better performance in corrosion and wear behaviour than the material the tube is made of can offer. The situation can be improved when the tube is coated with a protective film. This is possible with ion beam sputter coating. A conical or elliptical sputter target is moved through the tube. A well collimated ion beam enters the tube parallel to its axis and impinges onto the target. Thus, material is sputtered from the target onto the inner walls of the tube. With this method, tubes of different materials were coated, such as steel with TiN.
The Fe-incorporated carbon nanofibers (Fe-CNFs) grew on the graphite plate surface irradiated by Ar+ ions with a simultaneous Fe supply. The average diameter and length of the Fe-CNFs were in the range of 10-50 nm and 0.5-3 μm, respectively. As confirmed by TEM observation, the Fe-CNFs thus grown were characterized by amorphous-like or very fine crystalline nature. Compared with bulk Fe, they possessed higher coercivities for both parallel and perpendicular directions to the substrate at room temperature. In addition, magnetic properties of the Fe-CNFs strongly depended on the Fe content: The higher the Fe content, the stronger the saturation magnetization, whereas perpendicular coercivity was obtained for lower Fe supply rates.
A plasma based ion implantation (PBII) to Si wafers with N ions is performed and the surface modification of Si, i.e., the compositional and structural changes at the surface, are examined by energy dispersive X-ray spectrometer (EDX), Raman and Fourier Transform Infrared (FT-IR) spectroscopy, Rutherford backscattering spectrometry (RBS), X-ray diffraction (XRD) measurements and X-ray photoelectron spectroscopy (XPS). To check ion species in N2 plasma, optical emission spectroscopy is also carried out. The implantation time is varied from 10 min to 7 h. It is found that the N concentration is increased with increasing implantation time up to 1 h, and then tends to be saturated at further implantation time. The results of Raman measurements indicate that the small peaks from a-Si and/or a-SiNx appear after N ion implantation in addition to the Raman peak from Si crystal. It is also confirmed by FT-IR and XRD measurements that a broad peak assigned to Si-N bonds appears and no crystal phases of Si3N4 is observed after N ion implantation. That the maximum N areal density is approximately 1.7 x 1017 atoms/cm2 is obtained for the sample implanted for 7 h. The XPS results show that implanted N mostly bonds to Si, and the ratio of N/Si at the surface is slightly increased over 1 h until 7 h. Judging from these results, it is suggested that a-SiNx is formed on Si wafer by N ion implantation using PBII system.
Si ion implantation was widely used to synthesize specimens of SiO2 containing supersaturated Si and subsequent high temperature annealing induces the formation of embedded luminescent Si nanocrystals. In this work, the potentialities of excimer UV-light (172 nm, 7.2 eV) irradiation and rapid thermal annealing (RTA) to enhance the photoluminescence and achieve low temperature (below 1000 ℃) formation of Si nanocrystals have been investigated. The Si ions were introduced at acceleration energy of 180 keV to fluence of 7.5 x 1016 ions/cm2. The implanted samples were subsequently irradiated with a excimer-UV lamp. After the process, the samples were rapidly thermal annealed before furnace annealing (FA). Photoluminescence spectra were measured at various stages at the process. We found that the luminescence intensity is strongly enhanced with excimer-UV irradiation and RTA prior to conventional FA at 1050 ℃. Moreover, effective visible photoluminescence is found to be observed even after FA at 900 ℃, only for specimens treated with excimer-UV lamp and RTA, prior to a low temperature FA process. Based on our experimental results, we discuss the effects of excimer-UV lamp irradiation and RTA process on the luminescence.
Structure of implanted Br ions has been studied in 2.4MeV 6x1016 Br ions cm-2-implanted silica glass by X-ray absorption spectroscopy. It was found that most of implanted Br atoms form Br-Si bonds in as-implanted glass. Br atoms were substituted for oxygen atoms in SiO4 tetrehedra to form SiO3Br tetrahedra. About 60% of Br atoms formed Br2 molecules in the glass after heating at 600℃.
The cathodeluminescencs (CL), photoluminescence (PL), and electroluminescence (EL) properties of Ge implanted SiO2 films (SiO2:Ge) were investigated. The SiO2 films on Si substrate were implanted with Ge-negative ions. The implanted Ge atom concentrations in the films were 3 and 6 at. %. Ge nanoparticles were formed in the SiO2 films after annealing. CL, PL and EL were observed at wavelengths around 400 nm from the SiO2:Ge films. CL of GeO2 films were also investigated. The CL intensity from the GeO2 films is obviously lower than that from the SiO2:Ge films with 6 at.% of Ge atomic concentration. Strong EL from large area of the films was not only to be easily seen with naked eye but also to be measured its wavelength. Ooperating voltage was an order of magnitude lower and the emitting area was two orders of larger than those reported previously. These results suggested that annealing of SiO2:Ge films in moderate oxidative atmosphere is suitable method for the strong luminescence due to Ge-related oxygen deficient center (Ge-ODC).
In order to investigate the interactions of ethanol cluster ion beams with solid surfaces, various kinds of substrates such as Si(111), SiO2 and Au substrates were irradiated at different acceleration voltages and retarding voltages for ethanol cluster ions. RBS channeling measurement showed that the irradiation damage of the Si surfaces by the ethanol cluster ions was smaller than that by the Ar monomer ion irradiation at the same acceleration voltage. It was also found that the formation of damage-free surface was achieved by adjusting the acceleration voltage and the retarding voltage for the ethanol cluster ions. Furthermore, the sputtering process was investigated by changing the retarding voltage and the incident angle, and chemical sputtering was found to be predominant for the Si surfaces. The surface roughness decreased with increase of the retarding voltage, and it was less than 1.2 nm. On the other hand, for SiO2 and Au surfaces, physical and lateral sputtering was achieved, and the sputtered depth decreased with increase of either the retarding voltage or the incident angle.
Silicone rubber was irradiated with a mixed beam of oxygen cluster and monomer ions or an oxygen cluster ion beam. The contact angle on the surface of the silicone rubbers decreased with an increase in the dose of the beam. The contact angle decreased with increasing acceleration voltage when an oxygen cluster ion beam was irradiated. On the other hand, the low contact angle obtained by the irradiation of oxygen cluster ion beams at acceleration voltages of 6 and 9 kV was realized by the irradiation of a mixed beam of oxygen cluster and monomer ions at an acceleration voltage of 3 kV. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy results indicate that the oxidation caused by the irradiation might be the cause of the decrease in the contact angle.
Depth profiling has been rarely used with secondary ion mass spectrometry (SIMS) of organic materials, because the primary keV atomic ions produce weak signals for large molecules and often damage them during the etching process. In previous studies, we have found extremely low-damage secondary ion emission from organic materials bombarded with large Ar cluster ions, and proposed to use large gas cluster ions as primary ions for SIMS. In this study, secondary ions were measured with a linear type time-of-flight (TOF) technique, and the application of large Ar cluster ion beams to molecular depth profiling of organic films is demonstrated. The intensities of molecular ions were kept constant, though the primary ion beam fluence exceeded the static SIMS limit. These results indicate that large Ar cluster ion beams could be used as powerful tools for SIMS depth profiling.
Large gas cluster ion beam technology answers expectations in the field of material modification, because it provides unique capabilities, such as atomic-scale surface smoothing, shallow implantation and high sputtering yield. The relationship between incident cluster size and irradiation effects observed with large gas cluster ion beam is not yet clearly understood, and in this work we used size-selected Ar cluster ion beam to study the effects of incident energy-per-atom and cluster size on sputtering and secondary ion emission. Incident Ar cluster ions were size-selected by using the time-of-flight (TOF) method. It was found that the secondary ion yields decreased more rapidly with decreasing incident energy-per-atom and that the threshold energy-per-atom for sputtering of Si and Si+ were different, because the ionization energy of Si was higher than the surface binding energy of Si. It indicates that cluster ion irradiation sputtered only neutral Si from the surface by under the specific conditions.
We investigated secondary ion mass spectrometry (SIMS) for cellular imaging with high spatial resolution. Cellular level imaging would require nanoscale processing techniques for removal of contamination from cell surfaces and exposing the inner matter of cells. In this study, we applied gas cluster ion beams to the etching of biological samples. Molecular ions were detected with high-intensity from cholesterol samples etched with Ar cluster ions. Additionally, the intensity of secondary molecular ions with gas cluster ion irradiation was compared to that with Au3+ or C60+ beam irradiation and we demonstrated the advantage of using gas cluster ions as etching beams for biological samples with low damage. Finally, we performed etching of animal cells with Ar cluster ions and SIMS analysis of the etched cells. We demonstrated that the cell surfaces were etched with low damage by using gas cluster ion beam.
We report on the monolayer formation of hydrocarbons with terminal groups of thiol, hydroxyl and alkynyl groups on H-terminated silicon using UV light in order to clarify the ability to form the well-defined monolayer. The each molecule was dissolved in the solution (100 mM) and irradiated with UV light on the Si-H substrate. The monolayer formation was investigated by water contact angle, XPS, AFM and ellipsometry. The molecules formed hydrophobic monolayer, but the densities of the monolayers were loose. The hydrocarbons with thiol and vinyl formed the most densely packed monolayer based on the photochemical reactivity with Si-H.
In a GTA (Gas Tungsten Arc) welding, large amount of high temperature metal vapor is generated from the melting tip of a welding wire, a droplet and a weld pool. In this process, high temperature metal vapor is cooled rapidly and oxidized during diffusion to the surrounding air. Then a primary particle (nanoparticle), whose size is approximately 1nm～100nm, is formed through a nucleation. Furthermore, a part of these particles condenses and produces a secondary particle whose maximum size is over 1μm. It becomes the form of smoke and rises with the ascending current from the high temperature weld pool. They are called welding fume. For reducing the quantity and controlling the size of the fume, we integrated a fume formation model and visualized the fume formation process. Simulation was calculated changing physical property. Fig. 1 represents a secondary particle. The secondary particles with beaded (chain-like) shape composed of small particles whose sizes are approximately below 100nm were observed. As a result, it was confirmed that the shapes and the sizes of the secondary particles obtained in the simulation approximately agrees with that in the experiment.
In order to control the hydrolyzability and biodegradability of polyurethane, poly(carbonate/ester-urethane)s containing the lactide oligomer were prepared and their hydrolyzabilities were evaluated. Poly(tetramethylene carbonate/lactide-urethane)s (PC/LU), poly(lactide-urethane) and poly(tetramethylene carbonate-urethane) were synthesized by the polymerization of hexamethylene diisocyanate with the oligo(tetramethylene carbonate) diol and oligolactide diol at different feed ratios. The PC/LUs were ydrolyzed in alkaline solution and the PC/LU containing the oligocarbonate tended to show a resistance to hydrolysis. As for the enzymatic degradation, the PC/LU with a higher oligolactide content was more readily degraded by proteinase K in an aqueous solution. On the other hand, the PC/LU with a high oligocarbonate content was readily degraded by the immobilized lipase in anisole.
Removal of phenolic compounds, such as bisphenol A (BPA), from their aqueous solutions by the system based on the ionic complex of poly-carboxymethylated β-cyclodextrin (CM-β-CD) and chitosan was investigated. The β-cyclodextrin was reacted with monochloroacetic acid to yield CM-β-CD as Na salt After treatment of the obtained CM-β-CD with cation exchanger, the CM-β-CD and chitosan formed an ionic complex and worked as an adsorption system for BPA This system is based on the inclusion phenomenon between of BP A and CM-β-CD and the ionic interaction between the CM-β-CD and chitosan. The adsorbed BPA was released by treatment of the CM-β-CD/chitosan complex with 50-vol% ethanol and the refreshed complex adsorbed BPA again. This adsorption system can be prepared more easily compared to the systems based on chitosan bearing CD derivatives by covalent bond or to the system consisted of cationic CD derivatives.
The preparation of layered double hydroxide (LDH) substituting Zn in the structure was attempted to create an environmentally.friendly photocatalyst with anion adsorption capacities. Zn-Al-substituting LDH with the Zn/Al molar ratio of 4 was synthesized by adopting the natural processes. The adsorption property of an anionic dye, methyl orange, on Zn-Al-substituting LDH was characterized by batch experiment. Zn-Al-substituting LDH exhibited an extremely high affinity for MO anions. The photodegradation behavior of methyl orange on Zn-Al-substituting LDH was evaluated by determining ultraviolet-visible absorption spectra under ultraviolet light irradiation. The results indicated that Zn-Al-substituting LDH certainly showed the photocatalytic activities for methyl orange, and the degradation reaction of methyl orange was accelerated without being stabilized under ultraviolet irradiation. It was expected that Zn-Al-substituting LDH could be utilized as an efficient photocatalyst for harmful organic anions.
We have demonstrated systematic studies of plasma-induced copper nanoparticle deposition onto a poly(4-vinylpyridine)-grafted-poly(tetrafluoroethylene) surface, as well as their autocatalytic characteristics for the initiation of the following electroless copper plating. The plasma-induced reduction of the organo-copper precursor gradually increased the surface copper concentration owing to the formation of the copper nanoparticles with treatment time. The concentration became maximal at 300 s of treatment, and then it progressively decreased with further plasma treatment. XPS, SEM, and AFM experiments revealed that the total population of nanoparticles on the surface was clearly decreased, while the particles continued to grow. We found that thermodynamically driven spontaneous migration of Cu atoms occurred from the initially formed smaller particles to the larger ones, by the Ostwald ripening mechanism. The polymer surface densely and homogeneously seeded with copper nanoparticles enable the initiation of autocatalytic electroless deposition of copper layer at 40℃ with less than 5 s time lag.
Ordered metal coordinated peptide nano-arrays having redox protein, nitrate reductase (NR), on the surface were prepared on mixed self-assembled monolayers containing photo-responsive electron donors, ferrocenyl groups. The amino acid sequence of the peptide was chosen as Leu2Ala(4-Pyri)Leu6Ala(4-Pyri)Leu6. The complexation between metal and Pyridyl groups of the peptide induced the stable and vertically oriented a-helical bundle structure, whose macro-dipole moment was arranged unidirectionally on the surface. The non-linear effect of electron flow through the metal coordinated nano-array was observed along the peptide macro-dipole moment coupled with metal-(4-Pyri) complexes. Upon photo-excitation of ferrocenyl groups on the surface, vectorial electron flow occurred from the excited ferrocenyl groups to the redox protein, NR, at the terminal through the metal coordinated peptide bundle. The activated NR on the surface reduced the NO3-. The system may be useful for the novel molecular devices, such as nano-reactors.
Hydroxyapatite (HA) is a major component of bone and teeth. It has been proposed that octacalcium phosphate (OCP) and/or amorphous calcium phosphate are precursors of HA, and its evolution is regulated by specific proteins. Understanding the mechanisms by which biomolecules regulate the mineralization of calcium phosphates will provide guiding principles for fabricating biomaterials with properties similar to those of biological apatite. Dentin matrix protein 1 (DMP1) is the protein involved in bone and dentin mineralization. Synthetic peptides analogous to DMP1 motifs A and B have been shown to accelerate HA formation when they were immobilized on a glass surface. We have previously constructed artificial proteins by combinatorially assembling these two motifs, and found that one of the created proteins, namely, #64, accelerated HAP and OCP formation without immobilization. In this report, we investigated the effects of #64 derivatives on the crystal morphologies of calcium phosphates in mineralization experiments. Four #64 mutants, containing motifs in which the acidic residues were substituted with neutral residues, showed different levels of mineralization activity, and the resultant calcium phosphate precipitates had distinct morphologies, indicating a possible evolutionary path of calcium phosphates precipitated in the presence of motif-programmed artificial proteins.
A zwitterionic diblockpolypeptide of poly(L-lysine)-b-poly(L-glutamic acid) having 20 residues as the segment length of both blocks was synthesized and its self-assembling behavior in water was analyzed in detail. It was evidenced that nanofibers based on a coiled-coil-like motif was produced by accompanying with the sigmoidal transition in the secondary structure of blockpolypeptides. Such transition would generate a staggered helix-dimer with sticky-end and it was rearranged to the one-dimensional nanofiber structure.
A simple technique has been developed to surface modification from liquid solution by the solvent evaporation method. Using this technique, the preparation of lithium manganese oxide, LiMn2O4, which are the most promising cathode materials for lithium secondary battery, has been carried out for various operating conditions. The as-prepared samples exhibited a monophobic cubic spinel structure (fd3m) without any impurities in the XRD patterns, and the chemical composition of as-prepared powders showed in a good agreement with the one of precursor solution. The as-prepared sample was used as cathode active materials for lithium secondary battery and their charge/discharge properties have been investigated. Test experiments in the electro chemical cell Li|1M LiPF6 in EC with DEC|LiMn2O4 demonstrated that the sample, prepared by the solvent evaporation method, was a promising cathode material for 4V lithium secondary batteries.
Copper particles were synthesized in a batch reactor and concentric microreactor by the reduction-precipitation method. The products were observed by scanning electron microscopy, and their composition and crystal structure were measured by energy dispersive X-ray spectroscopy elemental analysis and powder X-ray diffraction (XRD), respectively. Spherical copper nanoparticles were prepared using a concentric microreactor. It was found that these particles had diameter less than 100 nm and contained copper and cuprous oxide. In addition, polyhedral particles were prepared in the batch reactor. Cubic particles could also be synthesized under certain conditions, and the size of the polyhedral and cubic particles was about 1 μm. Compared with the microreactor, the batch reactor produced particles that were larger and more varied in shape. However, the crystal structure of the particles prepared in each type of reactor was similar, as determined by XRD. The oxygen content changed with reaction time and the molar ratio of the reactants.
A unique hydrogel has been synthesized using supramolecular polyrotaxane as the starting material. Sparsely dispersed α-cyclodextrins threaded into long polyethylene glycol axle (Mw=35000) trapped with a stable capping agent, 1-adamantanamine of polyrotaxane (PR) unit was used for this purpose. The modification of the hydroxyl groups of α-CDs of the PR by a vinyl monomer containing an active isocyanate group at one end resulted in the formation of a stable carbamate bond with hydroxyl groups to give the modified polyrotaxane based cross-linker (MPR). Polymer gels were designed using MPR as a cross-linker and N-isopropylacrylamide, NIPA as a monomer and transparent, very soft, flexible, fast responsive and mechanically improved polymer gels could be obtained. The polymer chains can slide and rotate about the movable cross-linker in the gel network, which potentially improves the properties of the gels over conventional chemically cross-linked polymer gel.
High-density poly(N-isopropylacrylamide) (PNIPA) brushes were synthesized on silicon surfaces by surface initiated ATRP at various polymerization conditions. Polymerization was achieved using CuCl/tris(2-(dimethylamino)ethyl)amine (Me6TREN) as a catalytic system in DMSO at 20℃. The linear evolution of number average molecular weight (Mn) versus monomer conversion, the increase in layer thickness with polymerization time and relatively low molecular weight distribution (～ 1.2) indicate a well-controlled manner of polymerization. The average value of grafting density of PNIPA brushes was around 0.48 chain/nm2: We obtained high-density PNIPA brushes. During the measurement of air bubble contact angle under the surface of the PNIPA brushes in water, the surface property of PNIPA brushes shows an interesting phenomenon, which is antithetic to that of typical PNIPA gel. With the increase of temperature from 10℃, the surfaces of the PNIPA brushes gradually change to more hydrophobic natures. But as temperature approaches the LCST, the brush surfaces turned back to hydrophilic state. This might be the effect of the change in the surface morphology of the polymer brushes and/or the change in physical state of the terminal end groups of the polymer, depending on temperature.
Poly(amide amine) dendrimers with naphthyl units (Nn, n = 4, 8, 16, 32, 64) were synthesized for application as fluorescent chemosensor materials for metal cations. The metal cation recognition of Nn was also investigated. When Al3+, Zn2+, Cd2+, Ni2+, Mg2+, Ca2+, Ba2+, Co2+, or Ag+ were added to an acetonitrile/dichloromethane (1:1 v/v) solution containing Nn, the absorption spectra remained unchanged. However, the shape and intensity of the fluorescence spectra of Nn changed upon the addition of any of the metal cations except Ag+. Increasing n values of the naphthyl units resulted in selectivity for the metal cations. Selectivity for Al3+ and Zn2+, in particular, was excellent for N16, N32, and N64 dendrimers.
In the present study, the authors examined the heavy-metal-capturing properties of maleic acid/acrylamide (MA/AAm) gel which has plural carboxyl bases in a molecule. It was observed that the heavy-metal-capturing efficiency of the MA/AAm gel is very smaller than that of the sodium acrylate/acrylamide (SA/AAm) gel at the same AAm molar-fraction and total network density; in spite that the number of the carboxyl groups in the MA/AAm gel is twice as many as those of the corresponding SA/AAm gel. From the experimental results in the present study, it has been revealed that the heavy-metal-capturing functionality is influenced by the conditions other than the carboxyl-group number in the hydrogels.
Clouding-feature observations were made for several maleic acid/acrylamide (MA/AAm) gels with different fractions of MA and cross-linker concentrations for the first time. In the investigations, both of the conditions were found to considerably influence the turbidity of the MA/AAm gels. In addition, it was also found that turbidity of some MA/AAm gels changes with temperature, which indicates the inhomogeneity alteration.
We observed molecular dynamics of Dipalmitoyl Phosphatidylcholine liposome water dispersion by dielectric spectroscopy measurement. Statistical analysis of jitter used in the present paper is a new technique developed to observe dielectric behaviors more precisely in higher frequency range from 1 GHz to 30 GHz for time domain reflectometry method. Though the relaxation time obtained shows common temperature dependence, the relaxation time distribution parameter β decreased around the gel-liquid crystalline phase transition temperature with increasing temperature from 36 ℃ to 48 ℃. It is suggested that surrounding water of lipid membrane may form the particular water structure in the LC phase different from bulky water in the gel phase with a change in the mobility for hydrophobic regions of the lipid bilayer.
In the present study, the authors have investigated how the UV-ray irradiation affects the surface condition of wet and dehydrated poly(acrylamide/sodium acrylate) (PAAm/SA) gels. With large amounts of the UV-ray dosage, the wet PAAm/SA gel readily disintegrates to wreak the surface erosion while the dehydrated gel exhibits considerable turbidness in spite of no remarkable change in outline. Besides, even with the smaller dosage spawning no appreciable change only by the UV-ray irradiation, some of the wet PAAm/SA gels turn significantly opaque by putting an aqueous CuCl2 solution on the surface, which indicates the breakup of the surface layer of the wet PAAm/SA gel.
In the differential scanning calorimetry (DSC), it was found that the transition behavior of egg-white gel is complicated in low water contents (wc = wwater/ wdried gel) ranging from 0.1 to 1.8. The thermogram shows a glass transition and peaks related to the melting and recrystallization of water. In the present study, the sol-gel transition behavior of albumin of chicken egg in low water contents (wc= 0.19-3.24) was studied by DSC. Moreover, the thermal behaviors of the gels were intensively studied. In a sol-gel transition process, four endothermic peaks were observed. The peak temperatures are increased as the water content wc is reduced (wc＜ 1). The thermal behavior of albumin gel showed complicated behavior similar to the egg-white gel. Amount of free water (which is frozen at 0 ℃) in the gel is estimated from the thermogram.
A DNA-immobilized-gel could be used for functional materials such as sensors or adsorbents of carcinogenic agents which bind DNA by the intercalation. In the present study, DNA-polyelectrolyte complex gels are prepared by the method utilizing the complex formation between polyanions (DNA) and polycations (copolymer of N,N-dimethylaminopropylacrylamide, methyl chloride quarternaly and N,N-dimethylacrylamide). Swelling and mechanical properties of the gels are measured as functions of the concentration of crosslinkers and the molar ratio of cationic monomers. Adsorption of acridine orange (AO) as a kind of DNA intercalators to the complex gel is measured, and the adsorption efficiency of the gel is found to depend on the monomer composition of the matrix gel network.
In the present study, nearly monodisperse gelatin microparticles were prepared and their thermal and rheological properties were measured. The SPG (Shirasu porous glass) membrane emulsification technique was used to prepare the particles with a narrow size distribution. The particles were cross-linked by UV irradiation in order to control the stability at higher temperatures. The packing density of the particles after the application of the centrifugal force was measured to estimate the deformability of the microparticles.
Konjac glucomannan (KM) is a water soluble glucomannan with high molar mass. KM aqueous solution shows extremely high viscosity. KM can be depolymerized by chemical hydrolysis. The molar mass of hydrolyzed KM decreased with increase of hydrolysis time. The acid hydrolysis led chain scission of KM, but introduced no significant new chemical groups into the structure. The weight-averaged molar mass,Mw, of original KM and that of 30 min hydrolyzed KM were 1.0 x 106 Da and 6.0 x 103 Da, respectively. The weight-averaged radius of gyration, RG, of original KM was 98.0 nm. The RG value decreased with increase of hydrolysis time and then reached to below 10 nm at 20 min of hydrolysis time. SPM image of original KM molecular chain showed string-like pattern. The contour length and the chain height of original KM were 1193 nm and 1.2 nm, respectively. The chain height scarcely changed regardless of molar mass, but the contour length decreased significantly with increase of hydrolysis time. The chain lengths of KM with Mw of 5.9 x 105Da and 1.8 x 105 Da were 688 nm and 268 nm, respectively.
Quaternary ammonium functionalized radial compounds n-C10I (n = 3, 4, 8, 16), n-C10Br (n = 3, 4) and their reference non-radial compounds 1-C10X (X = Br, I) were synthesized and their antibacterial properties for gram-positive bacteria (Methicillin-resistant Staphylococcus aureus; MRSA) and gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) were investigated. The antibacterial activity for tested bacteria depended on the number of the terminal quaternary ammonium unit, and the influence of the counter anion for antibacterial activity was not observed. The antibacterial activity of 3-C10X (X = I, Br) for MRSA was the highest in tested bacteria.
A novel heterogeneous transition-metal catalyst, a polymer-supported terpyridine.palladium(II) complex, was prepared and found to promote the Mizoroki.Heck reaction in water between aryl halides and styrenes under aerobic conditions with high to excellent yield. The catalyst was recovered and reused several times without loss of catalytic activity.
Preparation condition of SrS:Cu thin film electroluminescent element (EL) elements was investigated to improve blue-EL-emission properties. The sintering temperature and time were fixed at 600℃ and 1h, respectively. The Cu2S concentration of 0.5 mol% was used. The effect of the thickness of SrS:Cu emission layer on the crystallinity of EL elements was investigated. The best crystallinity was obtained under the thickness and deposition time of 18000Å and 3h, respectively. A rapid thermal annealing (RTA) process at 700℃ was also effective to improve crystallinity of EL elements. This RTA process was better than the normal annealing process at 450℃, 2min. From a dynamic force measurement (DFM), The surface roughness of EL elements was smallest after the RTA annealing at 700℃, 2 min.
The Ga2O3 has an oxygen detection characteristic at higher than 900℃, so this material attracts much attention as an oxygen sensor at high temperature. The β-Ga2O3 films have been prepared by a RF magnetron sputtering method. The influence of annealing process on the crystal properties was investigated. The effect of the measuring temperature on the crystal properties was also investigated. It was found that the crystal properties of films depend on the annealing temperature. The oxygen sensing properties were stabilized at the measuring temperature of 1000℃.
Low-temperature preparation of the TiO2 thin films was examined by using a RF magnetron sputtering method. TiO2 films of anatase structure were prepared on the non-heated glass substrates. The photocatalytic properties of films were superior in the films prepared under the sputtering atmosphere of 10 Pa rather than 5 Pa. They showed high activities in the organic material-resolution characteristics. They also had high activity in the hydrophilicity characteristics.
Magneto-resistance effect was studied for the (WO3)x(CrO2)1-x granular system. WO3 was added to half-metallic CrO2 and the mixture was sintered at about 473 K in pure Ar gas. Magnetization M at room temperature decreased non-linearly with increasing x, showing that the influence of WO3 exists on the band structure of CrO2. Enhancement of magneto-resistance ratio was observed at x～0.8 which is the percolation threshold of CrO2 conducting path. There is a possibility of multi-ferroic TMR in the present system.
The fixation of carbon dioxide is one of the most important subjects in environmental research. The general approach to removing carbon from the atmosphere is to grow plants that sequester carbon dioxide in their biomass by photosynthesis. Recently, biochar, which is produced by the pyrolysis of trees, grasses or crop residues, has been undergoing a renaissance as a method for sequestering carbon dioxide. In our research, we applied a new compost containing biochar. The composting of agricultural and food industrial waste biomass occurred by the degradation of organic compounds by aerobic microorganisms in nature. Biochar has porous structures so that the blending of biochar into compost creates an aerobic environment which leads to the activation of aerobic microorganisms and the degradation of organic compounds in compost. In this study, we made a biochar-blended compost using waste biomass in Aomori. The biochar-blended compost contained a high amount of microorganisms. The growth of some vegetables was accelerated by treatment with this compost compared to ordinary compost. These results indicated that our biochar-blended compost has potential to be used in methods for the recuperation of degraded soil and the formation of soil environment.
As one of the basic areas of research for improving the electromagnetic environment, the present authors have developed a slit carbon plate, as a natural resource, that displays orientation characteristics in a radio frequency (RF) magnetic field. When the slit was held perpendicularly to the ground, the value of RF magnetic shielding degree SDHP increased with frequency in the region of 1 MHz (7 dB) to 3 GHz (70 dB). When the slit was held horizontally to it, the values of RF magnetic shielding degree SDHH indicated an average value of approximately 10 dB over this frequency region. The difference in the values, SDHP-SDHH, indicated the orientation characteristics. The slit carbon plate was particularly effective with respect to the orientation characteristics at frequencies above 70 MHz. However, the values of SDHP-SDHH below 70 MHz, having an average value of approximately 15 dB, were not significant enough to display orientation characteristics. Accordingly, the present research improved the orientation characteristics by construction of a slit carbon plate sandwiched between two slit ferrite plates; termed the slit sandwich plate. The value of SDHP-SDHH for the slit sandwich plate improved by an average value of 40 dB in the frequency region from 1 MHz to 70 MHz. The above results confirmed that an important criterion was developed for the fabrication of a slit sandwich plate having highly reliable orientation characteristics.
The properties of mutant glucoamylases（GlaBs） from Aspergillus oryzae H-1 and G-4 strains with a high level of GlaB activity were compared with those of native GlaBs from parental strains. Amino acid compositions of both mutant GlaBs were different from those of native GlaBs, with a particular decrease in Ser residue of mutant GlaBs. Moreover, N-linked suger chains of native and mutant GlaBs were considered a complex or hybrid type, and not a high mannose type. Because N-linked sugar chain of each GlaB mainly consisted of galactose and N-acetylglucosamine, there was little mannose. Since a little more galactose and N-acetylglucosamine combined per mannose were found in the N-linked suger chains of mutant GlaBs than of native GlaBs, this suggested that each N-linked sugar chain length of mutant GlaBs was possibly shorter. Native GlaBs were not deglycosylated with Endoglycosidase H, while both mutant GlaBs were deglycosylated. This result suggests N-linked suger chain structures of both mutant GlaBs changed from a complex type in native GlaBs to a hybrid type. In circular dichroism spectra analysis, Tm values of GlaBs from H-1 and G-4 strains were approximately 53℃ both, and thus similar to Tm of native GlaBs. Therefore, the thermostability of mutant GlaBs was shown as not being affected by mutation.
The purpose of this paper is to investigate possiblity of using bamboo as an architectural material. To meet the objective, we assessed basic mechanical characterustics of moso bamboo and proposed an architetural building which has truss system. The chord of the system has bamboo laminated lumber as a cotter and a joint using epoxy resin which is devised by us. The strength of the joint is also examined through force application test. The building was constructed at a memorial event site celebrating the 150th anniversary of the opening of Yokohama Port. Finally, the strength of the bamboo structure was assesed by force application tests.
In order to extend the utilization of rice hull (RH) and the recycled plastic resins made from fishing nets, which have been drifted ashore on the coats, mechanical behavior for the composites of the resin and RH was analyzed. Fourier transformed infrared spectrometry (FTIR) and differential scanning calorimetry (DSC) measurements revealed that the fishing nets used in this study were composed of polypropylene (PP) and polyethylene (PE) materials. Results of the tensile and bending tests means that the composite of the recycled resin became more brittle by adding the RH. The tensile and bending elastic modulus of the composites increased with RH content, while the breaking stress and the degree of elongation in both tests decreased. It was found that decreasing rate of the breaking stress was reduced by the RH with the size less than 177 μm.
In Gas Tungsten Arc (GTA) at atmospheric pressure, it was not clear how the differences of emitter materials which were added in the tungsten cathode affect the physical behavior in the electrode region. A study of the current attachment at thermionic cathode for GTA was tried from numerical calculations of arc-electrodes unified model. Two-dimensional temperatures and fluid flow velocities of arc plasmas were calculated in the four cases, namely, W-2%ThO2, W-2%La2O3, W-2%CeO2 and W electrode. It was suggested that the current attachment at thermionic cathode was dependent on work function, melting point and Richardson constant of emitter materials, and the cathode shape and the current density around the cathode strongly affected to the temperature of arc plasma and the cathode jet. Calculation results of radial temperature distributions on the tungsten electrode surface and arc pressure distributions at the anode surface were similar to the tendency of the previous experimental results.
Oil palm EFB (Empty Fruit Bunch), the stem and the petiole were subjected to the phase-separation treatment (Phenol: p-Cresol, Acid: 72% Sulfuric acid), producing lignin-based polymers (lignophenols) and water soluble sugars. After centrifugations of the reaction mixtures, there were almost no interfacial solid materials between the organic phase and aqueous phase. This result indicates that the conversion of oil palm lignocelluloses into lignophenols and water soluble sugars were achieved almost completely. The FT-IR spectra and pyrograms of lignophenols from the stem and the petiole were similar to those from EFB. Through mild alkaline treatment, oil palm lignophenols gave only p-hydroxybenzoic acid, indicating that p-hydroxybenzoic acid is linked to the side chains of oil palm core lignins which consist of G (guaiacyl) and S (syringyl) units through ester linkage. Oil palm is composed of stem, FFB (Fresh Fruit Bunch) and leaves. All of them are high quality lignocellulosics. The stem is replanted every 25 years because of the height and the decreased production for FFB. FFB and leaves are formed sustainably during lifetime. We can obtain post petroleum chemicals from oil palm, sustainably from EFB and leaves and cyclically from stem.
We have studied for a development of heating equipment for plastic greenhouses utilizing renewable woody biomass. Taking safety into consideration, we newly made a sealed type of experimental furnace and gas treating device. Carbon monoxide concentration and odor in the smoke emitted during thermal decomposition of the woody biomass were measured and the results are shown.