Carbon negative-ion implantation into proteins of bovine serum albumin (BSA) and avidin to change protein-binding capability for patterning cell adhesion with positive-pattern (PP) and negative-pattern (NP) on polystyrene (PS) were investigated. Hydrophobic PS and hydrophilic one were coated with 5-mg/ml BSA and 500-μg/ml avidin, respectively. After ion implantation at 10 keV and fluences of 1×1014 – 3×1015 ions/cm2, XPS analysis showed decrease of protein amounts on PS with an increase in the ion fluence. Fluorescent dye-conjugated biotin labeling also confirmed the degradation of protein-binding capability. Brightness patterns were found on the implanted region (PP) for C¯-implanted BSA-coated PS (C¯- BSA/PS) with 1-μg/ml avidin coating and on the unimplanted region (NP) for C¯-implantation into avidin-coated PS (C¯-avidin/PS). After culturing nerve-like cell, the clear cell-adhesion patterns of PP and NP were found on the implanted regions for the avidin coated C¯- BSA/PS and on the unimplanted regions for the C¯-avidin/PS at ion fluence of 1×1014 ions/cm2.
Degradations of the adhesive proteins of gelatin (GEL), laminin (LN) and poly-D-lysine (PDL) on polystyrene (PS) by carbon negative-ion implantation for nerve-cell adhesion patterning were investigated. Solutions of adhesive proteins were in the concentration ranges of 5 – 1000, 0.5 – 50 and 0.5 – 33 g/ml for GEL, LN and PDL, respectively. The ion implantation conditions were set at 10 keV and fluences of 1014 – 1016 ions/cm2. Based on XPS analysis, the suitable protein concentrations for coating the pre-treated PS with C¯-implantation at 10 keV and 3×1015 ions/cm2 were in the ranges of 5 – 1000, 2.5 – 50 and 5 – 33 g/ml for GEL, LN and PDL, respectively. After C¯-implantation into the protein-coated PS with concentrations, amounts of proteins left on PS were evaluated by XPS. Amount of all proteins decreased with an increase in the ion fluence. After in vitro cell culture, the cell-adhesion patterns on the unimplanted regions of GEL-coated PS at 5 μg/ml and LN-coated PS at 2.5μg/ml for rat adrenal pheochromocytoma cell (PC12h) and that on the unimplanted region of PDL-coated PS at 5 μg/ml for rat embryonic brain cortex neuronal cells were obtained at ion implantation fluence of 1014 ions/cm2.
Polyglactin is a bioadsorbable polymer used as tissue engineering scaffolds. However, it has poor cell attachment properties. In this study, polyglactin mesh is irradiated with Kr+ to improve their biocompatibility. Kr+-irradiation was performed into the mesh at an energy of 50 keV with a fluence of 1×1013, 1×1014 and 1×1015 ions/cm2, respectively. After the irradiation, the changes of original chemical bonds and the production of new functional groups were measured by Fourier transform infrared spectroscopy (FT-IR-ATR). Hydrolytic degradation of irradiated meshes was carried out in phosphate buffer solution (PBS). In animal studies, these meshes were wrapped around the carotid arteries of rabbits. Fibroblast cells (L929) were seeded on non-irradiated and irradiated meshes. The scission of original chemical bonds was caused by ion beam irradiation with increasing fluences. Irradiated meshes degraded in the same manner as non-irradiated. Seeded cells attached and spread well on irradiated meshes compared with non-irradiated. Irradiated mesh adhered well and inhibited the inflammation and thickening of the vascular wall. Irradiated polyglactin meshes exhibit excellent biocompatibility and retain its biodegradability. Thus, ion beam irradiated polyglactin will be useful for clinical applications.
The enormous progress of synthesis and characterization of magnetic materials facilitated an immense increase in storage density and enabled a gigantic boom within the computer industry in terms of Moore’s law. Most notably, this development is based on the possibility to design shape-controlled nanostructures, such as nanowires.[2,3] Furthermore, due to the discovery of the giant magnetoresistance effect, it was possible to achieve improvement in the field of sensor devices, mainly in the fabrication of read heads for hard drives.[4,5,6] We have investigated the production of multilayered cobalt/copper as well as cobalt/platinum nanowires by a well-known electrochemical route, using track etched polycarbonate templates. The periodicity of the segment length of each material component varied along the wire axis in magnitude when applying deposition pulses of constant duration. To obtain metal segments of same length, we have analyzed diffusion processes and developed a pulse deposition technique that allows compensating for limitations due to mass transport during the electrochemical growth process.
Techniques of superimposed ion beam writing with different energies and species have been developed at Takasaki Ion Accelerators for Advanced Radiation Application facility, TIARA, of JAEA/Takasaki. A bridge structure was fabricated by the superimposed writing of a girder pattern with 0.5 MeV proton beam adjusting to the bridge pier pattern written with 3 MeV proton beam, using SU-8 photoresist films coated on cured epoxy resin sheets. An upstanding column array by the bridge structure was fabricated by the spot pattern writing of focused 260 MeV Ne7+ beam, aiming to the girder pattern. In the spot pattern writing, the events of single ion hit were detected with 500 hits per spots. This is the first report about the three dimensional micro fabrication using the focused heavy ion beam with several hundred MeV at the countable fluence. The establish of basic techniques for the fabrication of upstanding fine wire array was shown.
We investigated the sputtering rate and surface morphology of polymethylmethacrylate (PMMA) samples bombarded with Ar cluster ion beam with selected energy of 12.5 eV/atom. The incident cluster energy range was 10–60 keV/ion. The incident cluster ion was selected before irradiation by using the time-of-flight (TOF) method. Both the sputtering rates and the average surface roughness increased rapidly with increasing incident cluster size under bombardment with small cluster ion. Under bombardment with large cluster ion, the average surface roughness does not increase rapidly, although sputtering rates increased nonlinearly. It suggests that a cluster ion beam with large size would be effective for high speed etching without roughing the surface.
Ion-induced damage on organic materials has been evaluated with secondary ion mass spectrometry (SIMS). However, conventional sputter beams, such as SF5+, C60+ cannot etch the organic materials without inducing damage, and it is difficult to evaluate the depth distribution of the damage in these materials. Large gas cluster ion can etch organic materials without damage, and in this study the damaged layer thickness was evaluated by molecular depth profiling with Ar cluster ion beam. Arginine films were irradiated with 10 keV Ga+ at a dose of 1.0 × 1014 ions/cm2 with the aim of forming a damaged layer on the surface. The chemical structure of arginine was seriously damaged, as indicated by the non-detection of protonated arginine molecular ions after Ga+ ions irradiation. The peak intensity of the protonated arginine ion increased with increasing sputtering depth and saturated at the depth of about 30 nm. This value agreed with the projection range of the Ga+ ion indicating that the depth of the ion-induced damage was the same as projection range of the ion. Ion-induced damage layer thickness on arginine films were accurately evaluated by molecular depth profiling with Ar cluster ion beam.
Osteoblast patterning on silicone rubber was investigated by using mesenchymal stem cells (MSC) and surface modification of the carbon negative-ion implantation. The ions were implanted at 3×1015 ions/cm2 and 10 keV through a micro-pattern mask. This mask consisted of the slit apertures of 50 μm in width and 150 μm in spacing. After 3 days cultures of osteoblast-like cell and MSC in the cell-growth media, only MSC adhesion could be patterned on the implanted region. After long-term culture of the patterned MSC in the osteogenic induction medium, the cells changed their cell shape from the elongated spread to the rounded spread and the osteoblast markers of type-I collagen and osteocalcin could be detected. The detections after 25 days culture indicated the osteoblast differentiation. As a result, the differentiation of MSC on the hydrophilic treatment patterning of carbon negative-ion implantation could be used for patterning osteoblast.
In industrial applications and environmental monitoring, amperometric gas sensors are very useful for detecting H2 and toxic gases. Expanded polytetrafluoroethylene (ePTFE) membrane was modified by high-energy ion beam irradiation to improve its gas sensitivity. The membrane was irradiated with N and Kr ion beams at energies of 5 MeV/nucleon and 4 MeV/nucleon, respectively, at fluences ranging from 1×1012 to 1×1013 ions/cm2. The energy loss of irradiated ions was simulated by the stopping and range of ions in matter. The irradiated ePTFE surfaces were characterized by field-emission scanning electron microscopy and Raman spectroscopy. The characteristic currents for H2 and toxic gases were measured by sensors equipped with non-irradiated and irradiated membranes. Chemical bonds were broken and the pore size increased with increasing fluences. The characteristic currents for H2 and toxic also increased with increasing fluences. The CO gas sensitivity of N-irradiated ePTFE reached a maximum of only 212%. Meanwhile, Ig/I0 for CO sensing was significantly enhanced by Kr-irradiation at a fluence of 5×1012 ions/cm2. This is due to the porous and amorphous structure on the membrane surface induced by ion beam irradiation. Thus, heavy ion irradiation was effective for improving gas sensitivity.
We performed micromachining of relatively thick siloxane films by proton beam writing (PBW) with beam energy of 1 MeV. The polydimethylsiloxane (PDMS) prepolymer films with a thickness of about 13 μm were spin-coated onto silicon substrates. After exposure to the 1-MeV proton beam (～1 μm in diameter), the samples were developed. The PDMS shows the behavior of negative resist and can be regarded as analog resist where the thickness of the structure gradually increases as a function of the proton beam (PB) fluence. Using this feature of the PDMS, we manufactured micro lenses with diameter of 40 μm by changing PB fluence. Micro-patterning of the PDMS films using scanning proton beam can offer a possibility of making three-dimensional structures for silica-based devices without baking and mask process.
The concentration and incident energy dependence of transient species Br2●– were obtained for aqueous NaBr solutions irradiated with pulsed H+ ion with energies of 20 MeV. The formation and decomposition of Br2●– were observed by transient absorbance method at 375 nm. Dose in irradiation pulse was evaluated by using GAF film dosimeter for the quantitative analysis of reactive species. The formation yield of Br2●– slightly increased from 0.73 to 0.85 (number of reactive species per absorbed energy of 100 eV) with the increase in the concentration of NaBr from 1 to 1000 mM. The formation yield of Br2●– for 1000 mM NaBr aqueous solution decreased from 0.85 to 0.27 with the decrease in the incident energy from 19.4 to 8.8 MeV, in other words, the increase in LET value from 4.79 to 8.81 eV/nm.
Diamond-like carbon (DLC) films are prepared on hard metal (WC-Co) substrates by a bipolar-type plasma based ion implantation. The mechanical properties and structural changes are examined by wear test and Raman spectroscopy as a function of negative pulse voltages (Vn) in the range of -5 to -15 kV. It is found that friction coefficient is around 0.2 for each sample. However, lower Vn causes better endurance (longer steady wear distance). Raman measurements reveal that the microstructure is changed to graphite-like structure after wear test. It is assumed that the degree of graphitization is larger as Vn increases.
Surface modification of stainless steel was examined by coating with DLC/Ti bi-layered films using sputter-deposition, in order to improve not only the abrasion resistance of the stainless steel but also the adhesion between the deposited DLC film and the steel surface by relaxing the stress concentrated at the interface between them. For the comparison, the sputter-deposition of DLC monolithic films onto the stainless steel was also performed under the same sputtering conditions as for depositing the DLC layers of the bi-layered films. Under visual observation, the obtained DLC/Ti bi-layered films appeared to be adhesive while the DLC monolithic films deposited directly onto the substrates peeled off partly. Thus it was found that the DLC/Ti bi-layered films were more adhesive to the stainless steel than the DLC monolithic films. According to Raman spectroscopy, it was found that a typical spectrum for DLC coatings was detected for the obtained DLC/Ti bi-layered film, confirming that DLC coatings were also formed on the titanium layer. Furthermore, according to indentation hardness measurements, the surface hardness of the DLC/Ti bi-layered films was much higher than that of the stainless steel substrates while the surface hardness of the titanium films deposited on the stainless steel substrates was slightly lower than that of the stainless steel substrates. Thus it was found that the surface hardness of the stainless steel could be improved by coating it with the DLC/Ti bi-layered films. On the other hand, according to potentiodynamic polarization experiments, it was also found that the corrosion protective property of the stainless steel could be improved by this coating process. Therefore it was expected that both the abrasion resistance of the stainless steel and also the adhesion between the deposited DLC film and the steel substrate as well as the corrosion property could be improved at the same time.
SWCNT-based supramolecular nanoarchitectures constructed by using photosensitizing electron-donors and acceptors to reveal efficient photoinduced charge-separation and their photovoltaic behavior are reviewed. In the presence of light harvesting porphyrins and phthalocyanines, the charge separation process is initiated from the electron transfer from photoexcited donor to SWCNT, whereas in the presence of electron accepting fullerenes, electron is captured by the photoexcited fullerenes from SWCNT under the visible light irradiation. Furthermore, in the presence of electron mediators such as alkyl viologen dication, these SWCNT-molecular nanohybrids undergo photocatalytic reaction. The band-gap dependent charge-separation efficiencies are demonstrated by utilizing the size-selective semiconducting SWCNTs in the photovoltaic cells.
C60 nanowhiskers (C60NWs) were synthesized by liquid-liquid interfacial precipitation method (LLIP method), using m-xylene as a good solvent solution of C60 and isopropyl alcohol (IPA) as a poor solvent of C60. The growth mechanism of C60NWs was investigated by the long-term observations using optical microscopy. In the early stage of growth, C60NWs grew faster and longer at 5°C than at 20°C. However as the growth time became longer, the growth rate of C60NWs became greater at 20°C than at 5 °C, and the longer C60NWs were obtained at 20°C than at 5 °C. Further, it is suggested that the growth of C60NWs proceeds by repeating the dissolution and reprecipitation process of C60NWs.
ESR spectra of fullerene nano-whiskers (FNW) are investigated to elucidate their electronic properties and the influence of oxygen absorption. A singlet ESR spectrum appears together with temperature independent Pauli-para type behavior in the area intensity (which indicates the magnetic susceptibility (χESR)) in vacuum. Motional narrowing of the absorption width is observed in vacuum due to fast molecule motion. Absorption of oxygen eliminates Pauli-para behavior and motional narrowing. Furthermore, creation of localized spins is observed and χESR shows no Pauli-para contribution after absorption. A kind of metal insulator transition due to gas absorption is therefore observed by ESR in the system of C60 FNW.
The preparation of finely dispersed and isolated MWCNTs for their safety evaluation was investigated by use of the fluid-jet cavitation method (FJCM). The used MWCNTs had the agglomerated structures combined by nodes. FJCM could partly cut the MWCNTs at the nodes and monodispersed MWCNTs were obtained, although the complete pulverization was not possible for heavily tangled MWCNTs. The fracture surfaces of MWCNTs showed both the convex and concave morphologies. A convex end showed a sharply-peaked morphology with a thickness of 14 nm. Those MWCNTs with pointed ends will be applicable to high-performance electron field emission devices.
Carbon films were synthesized on a Ni substrate by a chemical vapor deposition with ethanol at 900 °C followed by a rapid cooling. From the optical microscopic images, it is found that the film is composed of uniform grains with 3～8 μm. The Raman spectra show that the grains have high degree of graphitization. In addition, it is found that some of areas in the film exhibit 1-3 layer graphene, although they are minor in the film.
High-power piezoelectric characteristics of SrBi2Ta2O9 – Bi3TaTiO9 solid solution (Srx-1Bi4-xTi2-xTaxO9, 1 ≤ x ≤ 2, SBTT2-x) ceramics were investigated. Important piezoelectric constants for obtaining high vibration velocity are both piezoelectric strain constant d and mechanical quality factor Qm. In case of bismuth layer-structured ferroelectrics (BLSFs), they have been characterized as small d value but high Qm. In this study, High-power piezoelectric characteristics of SBTT2-x with high Qm more than 8000 in (33) vibration mode were measured using the Electrical Transient Response Measurement. At large-amplitude vibration, the Qm of these samples did not decrease with increasing v0-P < 2.5 m/s.
A molecular model was constructed for the network formation of RA4 + RB2 type polymerisation to be applied for the cure of diglycidyl ether of bisphenol A and polyoxypropylene diamino ether. The ring-forming parameter was introduced to measure the competition between intramolecular and intermolecular reactions, and incorporated into the model to improve classical gelation theory.
In order to clarify the effective regions that are substantially involved in the gelling process of plasma glycoprotein fibrinogen, we examined the aggregating properties of plasmin-treated fibrinogen, fragment-X. Two types of fragment-X were prepared by the digestion at 6°C and 37°C (fragment-XY and -XN, respectively). αC regions were cleaved thoroughly in both samples, but the amount of cleavage of BβN region differed between them (higher in the fragment-XN). Thrombin- and reptilase-catalyzed fibrin polymerizations were studied for both of the samples. Although the B-knob:b-hole interaction does neither work in the reptilase-catalyzed fibrin polymerization nor the αC-αC interaction is present, network formation proceeded in the fragment-XY with delayed polymerization. In the fragment-XN, protofibril formation occurred, but lateral aggregation did not. Mixing effect of intact fibrinogen showed that BβN region might play an important role in the lateral aggregation process cooperatively with αC-domain. .
The role of N-linked carbohydrate chains, bound to the polypeptide chains Bβ and γ of fibrinogen, in the process of fibrin gel formation has not been understood well yet, although it has been well known that the deglycosylation accelerates the fibrin polymerization. We investigated the time course of the fibrin polymerization employing the turbidity and light scattering measurements focusing on the role of carbohydrate chains. Deglycosylated bovine fibrinogen was prepared by using peptide N-glycosidase F, PNGF, and the effects of its mixing with the intact one were examined. Fibrinopeptide release and protofibril growth were not affected by the deglycosylation at all. However, only a slight mixing of deglycosylated fibrinogen by 5 and 10 % resulted in a markedly accelerated polymerization and the highly promoted switchover from the protofibril growth to the lateral aggregation of protofibrils. It was suggested that N-linked carbohydrate chains could interact with αC and BβN regions so as to suppress their releases from the central region of fibrinogen molecule, and play a regulating role of the switchover from the protofibril growth to the lateral aggregation.
For efficient transcatheter arterial embolization therapy, we have developed 12-hydroxystearic acid (HSA) microspheres containing mixtures of Canola oil and oil-based contrast medium, Lipiodol, as obstructing materials. The diameters of the obtained microspheres were in the range between 50 and 200 μm. The X-ray CT value for the microsphere suspensions was controlled by the mixing ratio of Canola oil and Lipiodol; The Lipiodol concentration range between 20% and 40 % corresponds to ca. 1000 HU that is favorable to avoid artifacts.
In the previous paper, we have reported the pH-dependent viscoelasticity of alkali-treated gelatin gel mixed with agar. The mixture formed a transparent and weak gel at pH below the isoelectric point (pI) of gelatin, while it formed an opaque and elastic gel at pH above the pI. Large effects of ionic strength on the viscoelasticity and the turbidity of the mixture were observed at the pH not greater than gelatin’s pI, which suggests that the mixture formed the gel via electrostatic interaction between positively charged gelatin and negatively charged agaropectin. In the present study, we examined the viscoelastic properties of acid-treated gelatin gel mixed with agar or agarose. Furthermore, direct measurements of the intermolecular interaction between gelatin and those polysaccharides were carried out by using a quartz crystal microbalance (QCM). G’ for the gelatin gel mixed with agar was strongly affected by pH. Below pH 8.5 corresponding to gelatin’s pI, the mixture of gelatin and agar formed an elastic gel with large G’. On the other hand, the mixture of gelatin and agarose formed a gel with smaller G’, and the values of G’ show weak pH dependence as compared with the mixture of gelatin and agar. It was confirmed by the results of QCM measurements that the gelatin interacts with agar at pHs below gelatin’s pI.
We investigated that the effect of demineralization on the hierarchical structure of bovine femur by means of simultaneous synchrotron radiation wide angle X-ray diffraction (WAXD) and small angle X-ray scattering (SAXS) measurement. The azimuthal intensity distributions at the 2θ of (002) WAXD reflection of bones with various degrees of demineralization obtained as a function of demineralization time (ti) indicate that the orientation of HAp micro-crystals is independent on the mineral fraction. The SAXS diffraction peaks due to the long period between the minerals deposited to the gap region of collagen fibrils were observed in the SAXS profiles for the intact bone and partially demineralized bones (PDBs). The ratio of the SAXS peak intensity of first-order diffraction to that of third-order diffraction was independent on the ti. The result indicates that the minerals deposited into the gap region of collagen fibril are homogenously demineralized in the 0.5 M EDTA solution. The SAXS profiles in the direction perpendicular to the bone axis suggest that the higher-order structure of bone was not affected by the demineralization up to ti = 2 h, whereas that was degraded at ti = 3.5 h.
When fibrinogen solution is incubated at low temperature, it converts to gel state spontaneously without the action of thrombin. The fibrinogen gel induced by low temperature is called “cryogel” and is associated with various diseases such as thromboembolic disorders, Raynaud’s disease and rheumatoid arthritis. In our previous paper, we have reported that cryogelation is inhibited by the addition of glucose and/or mannose. In this study, the additive effects of betaines on the cryogelation were examined. Betaines are known as the mild solubilization agents that prevent protein aggregation. Betaines used in this study are glycine betaine, non-detergent sulfobetaine (NDSB) -195 and Choline-O-Sulfate (COS) which is similar to NDSB-195. Bovine fibrinogen was dissolved in a phosphate buffer saline solution at the concentration of 3 mg/ml. Respective betaine was added to the fibrinogen solution at various concentrations, and turbidity measurements of those solutions were carried out over the wavelength range of 350 to 800 nm at 2°C. The characteristic quantities to the fiber structure composing the cryogel network (mass/length ratio, radius and density of the fibers) were analyzed according to the procedure employed by Carr et al. Fibrinogen cryogelation was inhibited by the addition of the betaines. Among the betaines used in this study, the order of inhibiting effect on the cryogelation was in the order of COS > NDSB-195 > glycine betaine. Fibrinogen in the presence of COS or NDSB-195 formed loose fibers with low density.
Biodegradable blend hydrogels based on carboxymethyl cellulose (CMC) and carboxymethyl starch (CMS) were prepared by the radiation-induced crosslinking. Properties of the crosslinked CMC/CMS blend hydrogels such as gel fraction, degree of swelling (Sw), gel strength, and biodegradability were investigated. The Sw of the CMC/CMS blend hydrogels were in the range of 10 to 800, which depended on the dose as well as on the CMC/CMS ratio. The gel fraction and the Sw of the CMC/CMS blend hydrogels obtained at the same dose decreased and increased, respectively, with increasing CMS content. The biodegradability of the CMC/CMS blend hydrogels was controlled by adjusting the CMC/CMS ratio, resulting in the biodegradation ratio in the range of 5% to 20% after 30 days in controlled compost.
In the present study, the authors have newly developed polarity-composite hydrogels and have investigated their adsorption properties of the positive and negative rare-metal ions in order to search for the functional materials serviceable to effective and simple heavy-metal and rare-metal recycling systems. In the present study, it has been revealed that the newly developed polarity-composite hydrogels show high adsorption efficiencies of both of the positive and negative rare-metal ions which are comparable to the single-polarity hydrogels having been investigated by the authors. The features observed in the present study have demonstrated the newly developed hydrogels’ potential to be utilized in the recycling system from industrial wastes often called as “urban mine.”
Hydroxyapatite (HA) ceramics are used as artificial bones and adsorbents. The properties of HA particles are dependent on their morphology and composition. To reveal the effects of these factors, tailored HA particles are required. In the present study, HA particles with a controlled morphology and composition were prepared using the hydrothermal treatment of α- or β-tricalcium phosphate (α- or β-TCP) particles in an acidic or basic solutions at 120−240 °C. Plate-like HA particles were obtained when α-TCP was treated with the acidic solution. Rod-like HA particles were obtained when α-TCP was treated with the basic solution or when β-TCP was treated with the acidic solution. Rice-like HA particles were obtained when β-TCP was treated with the basic solution. The HA particles that were obtained under these conditions had a calcium-deficient composition, and the Ca/P molar ratio approached the stoichiometric value when the treatment temperature was increased. The morphology and composition of HA particles were controlled by selecting the starting materials and hydrothermal conditions.
The study describes the effect of cold rolling reduction of a cast Ti-rich Ti-Ni shape memory alloy (SMA) plate from a self-propagation high temperature synthesis (SHS) ingot. The composition of the ingot is Ti-49.8at% Ni. SMA plates were cast by lost-wax process from SHS ingot. Specimens were cold rolled by rolling machine. The cold rolling ratio is 0% (no cold rolling) and 10%. Differential scanning calorimetry (DSC) and tensile test specimens were spark-cut from casting plates. Heat treatment conditions are 400°C, 500°C and 600°C for one hour respectively. Transformation temperatures were measured by DSC at several heat treatment and cold rolling conditions. Mechanical properties were measured by tensile test. In this study we investigated the effect of cold rolling of cast Ti-rich Ti-Ni SMAs. In 10% cold rolling specimens, shape memory characteristics of casting specimen were improved.
In order to fabricate LaTiO2N electrodes, which have been reported as visible-light-active water-splitting photocatalysts, La2Ti2O7 films were prepared on titanium substrates as precursor films. The films were characterized by X-ray diffraction and field emission scanning electron microscopy. La2Ti2O7 films were prepared directly on titanium metal substrates by hydrothermal reactions using a titanium substrate and La2O3 powder in deionized water at 573 K for 60 h. The cell parameters of La2Ti2O7 prepared by hydrothermal reaction were a = 7.80 Å, b = 13.00 Å, c = 5.54 Å, and γ = 98.59°; these are in good agreement with published values. The effect of experimental parameters such as reaction temperature and time on crystallinity, film thickness, and surface morphology of the products has been studied.
Crystallized mesoporous wood carbon prepared at 850°C via two steps iron-catalyzed carbonization was washed with acid and then oxidized in air at 420°C for removal of iron and elimination of amorphous portion, respectively. The resulting carbon composed of graphitic nano-shell chains (GNSC) was equal or superior to highly electroconductive carbon, Ketjen black, in the ability as filler. The unique morphology of GNSC was featured by adequate crystallization and well developed mesoporosity in terms of the conductivity to achieve high dispersion in the matrix. Measurement of the quasi-inherent conductivity made in this connection disclosed the higher aptitude for this unusual wood-derived carbon than for Ketjen black.
Fluorescence behavior of nanoparticles of several aromatic compounds was studied. Doped nanoparticles were also studied. Transparent organic nanoparticles dispersed in water were prepared by reprecipitation method. Addition of polyvinyl alcohol in water improved nanoparticle formation significantly. Fluorescence spectra and fluorescence quantum yields were measured by an absolute photoluminescence quantum yield measurement system. Although many organic compounds we studied hardly fluoresced in nanoparticles, fluorescence quantum yields of nanoparticles made of anthracene and its derivatives were relatively high. Doping of anthracene nanoparticles with naphthacene quenched fluorescence of anthracene nanoparticles and strong fluorescence of doped naphthacene was observed. Fluorescence quantum yield of naphthacene doped anthracene nanoparticles was as high as 0.68. Fluorescence lifetimes were also measured. Anthracene nanoparticles had shorter fluorescence lifetimes than anthracene molecules.
Wood char of genuine well-developed turbostratic carbon with a nano shell structure, produced by catalytic carbonization, was used to generate an intercalation compound with H2SO4. The turbostratic wood char prepared at 900 °C with Ni-catalyzation was put as an anode and electrochemically treated in 98% sulfuric acid at 30°C. During the treatment, a plateau in the potential curve appeared implying intercalation with H2SO4. Evidence of the intercalation was obtained by X-ray diffraction. The intercalated compound was washed in water and dried, and the residue obtained was roasted for several seconds in a flame at 700–800 °C. Observations by SEM and TEM revealed exfoliation at a nano-ordered level. The residue had adopted a flocculent appearance, with stacked carbon layers peeled from the nano shell. This exfoliation was possibly caused by the intercalant trapped between the graphitic layers during the roasting. The intercalating capability of this turbostratic carbon with a nano shell structure from wood was indicated.
In order to improve the durability of performance of actuator using shape memory alloy, the effect of ambient temperature and Ni-content on function deterioration process of Ti-Ni shape memory alloy is investigated. The function deterioration process is investigated by repeated loading-unloading tests with constant strain condition. The chemical compositions of specimens are Ti-50.1 at%Ni, Ti-50.3 at%Ni and Ti-50.6 at%Ni and the cold working ratio is 43.0 %. Heat-treatment condition is at 673 K for 3.6 ks. The ambient temperature range is from 353 to 473 K. The decrement of recovery strain decreases with increasing of ambient temperature. It is caused by the increase of applied stress with increasing ambient temperature. However, when applied strain is about 2 %, the decrement of recovery strain hardly increases with increasing ambient temperature up to 433 K. From this result, when the applied stress is less than about 2 %, this sample can be used under a high temperature consecutively. Meanwhile, the increasing of Ni-content leads to the increasing of applied stress. However, the decrement of recovery strain decreases with increasing Ni-contents. This tendency is interpreted to be caused by the increase of precipitates (Ti3Ni4) and decrease of grain size with increasing Ni-contents.
In this research, the effect of heat treatment temperature on the recovery of function of Ti-Ni shape memory alloy (SMA) is investigated. The chemical composition of specimen is Ti-50.4 at%Ni, and cold working ratio is 30 %. At first, the specimen is heat-treated at 673 K for 3.6 ks. And then, the specimen is heat-treated for recovery of function after isothermal 1000 times loading-unloading test under constant strain. The heat-treatment temperature for recovery of function is performed at 573, 673 and 773 K for 0.6 ks. The functional deterioration process of specimens heat-treated for recovery of function is investigated by the isothermal loading-unloading tests under constant strain. Recovery strains of samples which heat-treated at 673 K and 773 K are recovered to the same level of initial condition by heat-treated for recovery of function. However, when heat-treated at 573 K, recovery strain does not recover. On the other hand, plastic strains of all samples recover to the same level of initial condition irrespective of heat-treatment temperature. Nevertheless, when heat-treated at 773 K, the increment of plastic strain is larger than other cases. From these results, the optimal heat-treatment temperature for recovery of function is 673 K.
The orthorhombic Pbn21 phase of Li2CoSiO4 has been prepared by solid state reaction of Li2CO3, CoC2O4・2H2O, and highly dispersed SiO2 at 900 °C and the subsequent slow cooling in Ar gas stream. The DTA curve shows peaks at around 540 °C indicating a reversible structural phase transition. XRD pattern of the sample quenched from 650 °C can be indexed as a Pmn21 phase. However, electron diffraction patterns show complex diffuse scatterings. From the in-situ XRD patterns at high temperature, a reversible second order-type phase transition from Pbn21 to Pmn21 phase was confirmed and it is interpreted as an order-disorder transition of Co and Li atoms. At high temperature, Pmn21 phase transforms to the monoclinic γ-phase with large thermal hysteresis; DTA curve shows peaks at 950°C on heating and at 780°C on cooling.
Shape memory alloys show unique properties such as the superelastic behavior or the shape memory effect. Various kinds of engineering applications are proposed to use these properties. To understand the behavior of engineering components of shape memory alloys under various loading conditions, it is necessary to calculate the transformation behavior of the material accurately. Furthermore, it is necessary to evaluate not only the transformation but also the plastic deformation when the plastic deformation occurs at the same time. The present paper shows example results calculated for the behavior of shape memory alloys in the combined states of the transformation and the plastic deformation. Calculations are made by applying a newly developed constitutive model which is an extended version of that of the “accommodation model” developed before by the authors for the transformation behavior of shape memory alloys.
This study discusses the heat teat treatment temperature on functional degradation properties. Tensile tests and cyclic tensile loading-unloading tests have been carried out using Ti-50.3at%Ni wires heat-treated at 673K, 723K and 773K for 3.6ks. The tensile strength and the breaking strength decrease increasing heat treatment temperature. The number of cycles to failure increases with increasing heat treatment temperature. However, the effect of maximum applied strain on the number of cycles to failure is small. The cumulative residual strain increases with increasing heat treatment temperature and it increases with increasing number of cycles. In addition, the cumulative residual strain of heat treatment temperature of 773K rapidly increases with increasing number of cycles during the first 10 cycles. The stress for inducing martensite decreases with increasing heat treatment temperature and it decreases with increasing number of cycles. The maximum stress decreases with increasing heat treatment temperature. The maximum stress of the maximum applied strain of 10% rapidly decreases with increasing number of cycles during the first 10 cycles.
Plasma metamaterials, which have periodic microstructure partly composed of plasmas, show extraordinary responses against propagating electromagnetic waves. One of these responses arises from states with negative refractive index, and the corresponding plasma metamaterial is promising on microwave plasma generation as well as control of electromagnetic waves. Another good example is deformation of spoof surface plasmons using a microplasma array. These phenomena are characterized both experimentally and theoretically. Furthermore, both linear and nonlinear properties are explored, which are also distinguishable in comparison with the ordinary metamaterials.
Carbon nanotube has been prepared on the Si substrate with metal nanodots on using chemical vapor deposition method. Carbon nanotubes and nanosize dot structural metal substrates can be prepared on the silicon by using one process in the same chamber. Size of the nanosize dot structural metal on the silicon was about 50~500 nm and dispersion of them is small. Size and density can be controlled by the substrate temperature. Carbon nano tube on the substrate was several hundreds nm in diameter, and their density can be controlled by substrate temperature and methane gas pressure
Hydrothermality, as it is applicable at relatively low temperatures, is regarded as efficient for the selective decomposition of industrial wastewater disposal containing organic pollutants. Electrical discharge produced by high-voltage pulsed power has gained attention as a recently developed method used to generate hydrothermality required to degrade organic pollutants in waste water as this method not only generates a hydroxyl radical, it also generates atomic oxygen with a high oxidation potential. Here, we utilize these conditions to study the removal characteristics for aniline and its products. The experiments were conducted at 353 K and 5 MPa using a batch type reactor. Intermediate compounds from the conversion of aniline in the aqueous products were identified by gas chromatography mass spectrometry (GC-MS) and quantified using high performance liquid chromatography (HPLC). Aniline can be considered representative of the aromatic ring structures present in waste water. The maximum aniline conversion was 30.21 % with a 10000 times pulsed discharge plasma. The conversion of aniline increased with the existence of the electric filed which produced by pulsed discharge plasma. The results suggest the use of pulsed plasma is effective at the decomposition of aniline in hydrothermal conditions.
Fabrication of nano-structured materials has been developed by performing pulsed laser ablation of gold and silver plates in supercritical CO2. The gold and silver nano-structured particles were successfully generated with allowing the selective generation of clusters. Laser ablation was performed with an excitation wavelength of 532 nm. On the basis of the experimental result, both surface of ablated gold and silver plates and structure of gold and silver nano-structured particles were significantly affected by the changes in supercritical CO2 density. As increasing irradiation time, plume deposited in the surrounding crater created by the ablation was clearly observed. In FE-SEM image of the generated gold nano-structured particles on silicon wafer, a network structure of smaller gold particles was fabricated. The network structure consists of gold nanoclusters with an average diameter of approximately 30 nm in ensembles of 300-800 nm length. The difference morphology of particles fabricated from silver plate was observed. Based on the results, this new method can also be used to obtain advanced nano-structured materials.
Multi-walled carbon nanocoils (MWCNCs) have been successfully synthesized by catalytic chemical vapor deposition (CVD) using Fe-Sn catalyst supported on mesoporous materials. Fe was supported on mesoporous materials in the ethanol solution of iron acetate, and Sn was deposited on the Fe-supported mesoporous materials using vacuum evaporation to form Fe-Sn nanoparticles. Zeolite and MCM-41 were used as a mesoporous material, and the length of Sn wire evaporated and reaction time were varied in the experiment. It was shown that zeolite with its smaller pore size worked better for MWCNCs growth than MCM-41 did. It is believed that the size of Fe-Sn catalyst nanoparticle was larger than that of the pores of zeolite and the catalyst nanoparticle stayed outside the pore, instead of entering into it. This makes carbon adsorption on catalyst nanoparticle easier during MWCNC synthesis. Evaporation of Sn for the formation of Fe-Sn catalyst resulted in a higher growth yield of MWCNCs than the previous catalyst supporting method that uses the acid solution of both Fe and Sn. Transmission electron microscopy observation revealed that MWCNCs grown have multi-walled graphitic layers (ca. 19 layers) with a hollow structure in the center of the tubes.
Microwave excited plasma source with slot antenna in water is a novel plasma applicable to materials processing in liquid. In order to apply this microwave plasma source to a practical use for solute decomposition, it is necessary to evaluate the decomposition efficiency for refractory organic solutes and understand the decomposition process of solution as well. In this paper, the microwave plasma treatment was demonstrated through decomposition of refractory organic solutes such as acetic acid, polyvinyl alcohol (PVA), and 4-chloro-2-methylphenoxy acetic acid (MCPA) in aqueous solutions. Total organic carbon concentration and high-performance liquid chromatography measurements revealed that the refractory organic substances such as acetic acid, PVA, and MCPA were decomposed by microwave plasma. Intermediate products of MCPA were investigated by gas chromatography coupled to a mass spectrometry and ion chromatograph during MCPA degradation using microwave excited plasma.
Arc discharge in liquid helium is a promising method for fabricating high-quality carbon nanomaterials. Measurements of the discharge characteristics of the resulting plasma and observation of the associated optical emission spectra show that the behaviour of discharge current over time and the associated spectra depend strongly on discharge voltage and both may be related to the temperature of the carbon target.
A gas-liquid interfacial discharge plasma is used for the DNA-associated synthesis of water-soluble gold nanoparticles (AuNPs) by reducing Au ions in aqueous chloroauric acid trihydrate. The plasma is generated by a pulse power source, which can avoid the instability of DC discharges at high pressures. The high discharge current (～ampere) offers a basis for the high rate synthesis of AuNPs. Single-stranded DNA is used as a stabilizing agent since the DNA molecules can be bound to the Au surface. The AuNP size and morphology can be tuned by the DNA concentration. The ability of DNA for stabilizing AuNPs is found to decrease with increasing the DNA length. We also synthesize AuNPs associated with different-base DNA consisting of guanine, adenine, cytosine, and thymine (denoted as dG30, dA30, dC30, and dT30). It is found that dG30 and dA30 have the stronger stabilizing ability for AuNPs than dT30 and dC30 by comparing the intensities of surface plasmon resonance (SPR) peaks of AuNPs after extracting them from as-synthesized samples by centrifugation.
Increasing the uniaxial-magnetic anisotropy in thin-film materials is a key issue for micro-magnetic devices driven at a GHz frequency. An especially high uniaxial-magnetic anisotropy is known to have been induced by only the carousel sputtering technique. We analyzed the atomic deposition process of Ru nano underlayer by using Monte Carlo simulation with respect to sputtered particles. The results indicated that the nano-interface of the Ru underlayer had brought the further reduction in surface energy. It was found that the nano-interface of the underlayer remarkably contributed to the higher uniaxial-magnetic anisotropy of the films.
The reaction of hydrogen plasma with Si(110) surface was investigated at the floating condition. The evolution of hydride components in Si(110) were monitored with the infrared absorption spectroscopy in multiple internal reflection geometry (MIR-IRAS). IR data indicate that the surface was terminated with hydrogen by the exposure to hydrogen plasma, and also indicate that the atomic arrangements of Si(110) surface were distorted, then abundant parts of the surface were changed in amorphous phase with forming dihydride. However, characteristic structures of -Si-Si- chains on crystalline (110) face were retained.
Carbon thin films were prepared on the carbide steel cylinder rod using new magnetron sputtering deposition method to prevent their corrosion and/or increasing friction coefficient. In this method, plasmas move toward axial direction using modulated magnetic field which was generated by low frequency alternating coil current. Experimental results suggest surface roughness of the film decreased to ～10 nm from ＞100 nm (substrate) by this deposition. Uniformity of the ion saturation current and film thickness increased by modulated magnetic field. Deposition rate of carbon films prepared using RF discharge at 50 W was higher than that using DC discharge at 500 V and 30mA, however hardness of the film prepared by DC discharge was higher than that by RF discharge.