Search

A nitronyl nitroxide unit (NN) was linked with a triphenylamine-based condensed polycyclic skeleton DOTT to form a radical substituted donor NN-DOTT. X-ray crystal structure analysis demonstrated a flat bowl shape of the DOTT unit. EPR spectra showed the localization of electron spin on the NN unit. Chemical oxidation of the DOTT unit produced radical-substituted radical cation salts NN-DOTT+ ⋅ SbF6 - and NN-DOTT+ ⋅ FeBr4 - that are stable under ambient conditions. The magnetic behavior of NN-DOTT+ ⋅ SbF6 - is characterized by the strong intramolecular ferromagnetic interaction between NN and DOTT+ . The X-ray structural analysis of NN-DOTT+ ⋅ FeBr4 - shows planar structure of DOTT and 1D mixed-stack column of NN-DOTT+ and FeBr4 - . Magnetic measurements established that NN-DOTT+ ⋅ FeBr4 - undergoes magnetic phase transition into a weak ferromagnet at 7 K.

This work proposes practically useful novel coating-type cover layer materials. A copolyimide (PI) system derived from pyromellitic dianhydride (PMDA, 50 mol%), 3,3′,4,4′-biphenyltetracarboxylic dianhydride (s-BPDA, 50 mol%) with 2,2′-bis(trifluoromethyl)benzidine (TFMB) showed a low coefficient of thermal expansion (CTE) by thermal imidization. However, this system was not compatible to chemical imidization process because of gelation. A structural modification of this copolymer by 4,4′-(hexafluoroisopropylidene)dianiline (HFIDA) significantly improved the solubility, as a result, allowed for chemical imidization in a homogeneous state and the formation of a stable PI solution from less hygroscopic solvents such as triglyme (TriGL). The TriGL-cast PI film at an HFIDA content of 25 mol% displayed excellent combined properties; a low CTE (22.9 ppm K −1 ), a very high T g (327 °C), and a common level of tensile properties [modulus ( E ) = 3.6 GPa and the elongation at break ( e b max ) = 10.4%]. The PMDA(50);s-BPDA(50)/TFMB copolymer system was also modified with other ether-linked fluorinated diamines; i.e., 2-trifluoromethyl-4,4′-diaminodiphenylether (3FODA) and 4,4′-bis(4-amino-2-trifluoromethylphenoxy)biphenyl (6FBAPB). At a 3FODA content of 25 mol%, the NMP-cast PI film displayed the lowest CTE (20.7 ppm K −1 ) among the PIs examined in this work. The modification using 6FBAPB was most effective to enhance the solubility. Thus, the structural modifications of PMDA(50);s-BPDA(50)/TFMB copolymer by these fluorinated diamines (HFIDA, 3FODA, and 6FBAPB) were an effective way to obtain almost satisfying target properties except for a high level of e b . A mechanism was proposed for explaining why the effect of the CF 3 -substituted ether-linked diamines on the toughness improvement was not so prominent. The approach simultaneously using some CF 3 -free ether-linked monomers enabled us to significantly enhance the film toughness ( e b max > 50%) while maintaining low CTE characteristics and good solution-processability. Thus, some of the PI systems can be promising candidates as novel coating-type cover layer materials.

The mechanism of dense vertically aligned carbon nanotube growth achieved by a recently developed thermal chemical vapor deposition method was studied using synchrotron radiation spectroscopic techniques., The mechanism of the one-order-of-magnitude increase in the density of vertically aligned carbon nanotubes (CNTs) achieved by a recently developed thermal chemical vapor deposition process was studied using synchrotron radiation spectroscopic techniques. In the developed process, a Ti film is used as the underlayer for an Fe catalyst film. A characteristic point of this process is that C2H2 feeding for the catalyst starts at a low temperature of 450°C, whereas conventional feeding temperatures are ∼800°C. Photoemission spectroscopy using soft and hard X-rays revealed that the Ti underlayer reduced the initially oxidized Fe layer at 450°C. A photoemission intensity analysis also suggested that the oxidized Ti layer at 450°C behaved as a support for nanoparticle formation of the reduced Fe, which is required for dense CNT growth. In fact, a CNT growth experiment, where the catalyst chemical state was monitored in situ by X-ray absorption spectroscopy, showed that the reduced Fe yielded a CNT forest at 450°C. Contrarily, an Fe layer without the Ti underlayer did not yield such a CNT forest at 450°C. Photoemission electron microscopy showed that catalyst annealing at the conventional feeding temperature of 800°C caused excess catalyst agglomeration, which should lead to sparse CNTs. In conclusion, in the developed growth process, the low-temperature catalyst activation by the Ti underlayer before the excess Fe agglomeration realised the CNT densification.

We reported an optical DNA/protein microfluidic sensor which consists of single stranded (ss) DNA-Cy3 probes on gold surface and simple line-shape microfluidic channel. These ssDNA-Cy3 probes with random sequence in bulk solution or on gold surface exhibits fluorescence enhancement after binding with complementary ssDNA (cssDNA) targets. Particularly it did not require complicated design or hairpin-like stem-loop conformation, which made it easier to be made and applied in analytes detection by fluorescence switching techniques. Using ssDNA-cy3 probes attached on gold surface in a microfluidic channel, strong fluorescence enhancement was measured by ssDNA with cssDNA binding or ssDNA with cssDNA-biotin binding. The following introduction of streptavidin resulted in fluorescence quenching (fluorescence decrease) because of the binding of hybridized DNA-biotin with streptavidin. This sensor showed strong affinity and high sensitivity toward the streptavidin, the minimum detectable concentration for streptavidin was 1 pM, equating to an absolute detection limit of 60 amol in this microfluidic channel. Microfluidic channel height and flow rate is optimized to increase surface reaction efficiency and fluorescence switching efficiency. In contrast to previously reported optical molecular beacon approach, this sensor can be used not only for the detection of cssDNA target, but also for the detection of streptavidin. This microfluidic sensor offers the promise of analyzing kinds of molecular targets or immunoreactions.

We demonstrate the current on-off operation in a novel dual-gated transistor with a He ion irradiated graphene channel in which defect-induced transport gap is formed. The transistor operation was performed by controlling the band configuration of gate-controlled p-i-n junction by independent biasing of top gates. The maximum current on-off ratio of nearly four orders of magnitude was obtained at a temperature of 250 K in the proposed device structure. It was also demonstrated that the transistor polarity can be changed between unipolar and ambipolar just by adjusting the gate bias of one of the dual gates, as expected from the device operation model. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The conduction properties of graphene were tuned by tailoring the lattice by using an accelerated helium ion beam to embed low-density defects in the lattice. The density of the embedded defects was estimated to be 2-3 orders of magnitude lower than that of carbon atoms, and they functionalized a graphene sheet in a more stable manner than chemical surface modifications can do. Current modulation through back gate biasing was demonstrated at room temperature with a current on-off ratio of 2 orders of magnitude, and the activation energy of the thermally activated transport regime was evaluated. The exponential dependence of the current on the length of the functionalized region in graphene suggested that conduction tuning is possible through strong localization of carriers at sites induced by a sparsely distributed random potential modulation.

Background Serum unbound bilirubin (UB) is a measure of bilirubin not bound to albumin, and has been reported to be better than total bilirubin level at identifying infants at risk of developing bilirubin-induced neurotoxicity, including auditory abnormalities. A detailed treatment strategy for newborns with high serum UB has not been established. The aim of this study was to assess auditory outcomes in newborns with serum UB ≥1.00 μg/dL who were treated according to a novel treatment protocol. Methods A prospective clinical study was conducted in newborns weighing >1500 g with serum UB ≥1.00 μg/dL who were admitted to Kobe University Hospital and Kakogawa Municipal Hospital, Japan from 2006 to 2011. Enrolled newborns were treated as follows: (i) if serum UB was 1.00–1.50 μg/dL, phototherapy and infusion were given with or without albumin or immunoglobulin therapy; and (ii) if serum UB was >1.50 μg/dL, exchange transfusion was performed immediately. Auditory brainstem responses were evaluated at the time of discharge. Results A total of 89 Japanese newborns with UB ≥1.00 μg/dL were enrolled at a median age of 4 days. Of these, 85 had UB 1.00–1.50 μg/dL and four had UB >1.50 μg/dL. After being treated according to the protocol, no newborns were diagnosed with auditory brainstem response abnormalities. Conclusions The present treatment protocol for Japanese newborns with serum UB ≥1.00 μg/dL may be useful for the prevention of bilirubin-induced auditory abnormalities.

For cell-based medicine, to mimic in vivo cellular localization, various tissue engineering approaches have been studied to obtain a desirable arrangement of cells on scaffold materials. We have developed a novel method of cell manipulation called “cell transfer technology”, enabling the transfer of cultured cells onto scaffold materials, and controlling cell topology. Here we show that using this technique, two different cell types can be transferred onto a scaffold surface as stable double layers or in patterned arrangements. Various combinations of adherent cells were transferred to a scaffold, amniotic membrane, in overlapping bilayers (double-layered cell transfer), and transferred cells showed stability upon deformations of the material including folding and trimming. Transplantation of mesenchymal stem cells from periodontal ligaments (PDLSC) and osteoblasts, using double-layered cell transfer significantly enhanced bone formation, when compared to single cell type transplantation. Our findings suggest that this double-layer cell transfer is useful to produce a cell transplantation material that can bear two cell layers. Moreover, the transplantation of an amniotic membrane with PDLSCs/osteoblasts by cell transfer technology has therapeutic potential for bone defects. We conclude that cell transfer technology provides a novel and unique cell transplantation method for bone regeneration.

Selective graphene growth on copper twin crystals by chemical vapor deposition has been achieved. Graphene ribbons can be formed only on narrow twin crystal regions with a (001) or high-index surface sandwiched between Cu crystals having (111) surfaces by tuning the growth conditions, especially by controlling the partial pressure of CH(4) in Ar/H(2) carrier gas. At a relatively low CH(4) pressure, graphene nucleation at steps on Cu (111) surfaces is suppressed, and graphene is preferentially nucleated and formed on twin crystal regions. Graphene ribbons as narrow as ~100 nm have been obtained in experiments. The preferential graphene nucleation and formation seem to be caused primarily by a difference in surface-dependent adsorption energies of reactants, which has been estimated by first principles calculations. Concentrations of reactants on a Cu surface have also been analyzed by solving a diffusion equation that qualitatively explains our experimental observations of the preferential graphene nucleation. Our findings may lead to self-organizing formation of graphene nanoribbons without reliance on top-down approaches in the future.

Background: The American Academy of Pediatrics guidelines recommend that the total bilirubin (TB)/albumin (Alb) ratio (B/A ratio), instead of serum concentration of unbound bilirubin (UB), can be used with TB for determining treatment modality for jaundiced newborns ≥35 weeks of gestation. It is unknown, however, whether the B/A ratio is actually correlated with serum UB. Methods: Four hundred and ninety-seven serum samples were obtained from 209 newborns ≥35 weeks of gestation, who were admitted to Kobe University Hospital. Serum UB concentration was measured using the glucose oxidase–peroxidase method. Serum TB and Alb concentrations were measured on spectrophotometry. B/A ratios were calculated and were linearly compared with serum UB. Furthermore, the accuracy of the B/A ratio was evaluated. Results: The B/A ratio was significantly correlated with serum UB concentration. A serum UB concentration of 0.6 µg/dL was in agreement with a B/A ratio of 0.5. For comparison of the number of newborns who had serum UB concentrations ≥ or 0.6 µg/dL.

The uridine diphosphoglucuronate-glucuronosyltransferase 1A1 (UGT1A1) gene encodes the enzyme responsible for bilirubin glucuronidation. To evaluate the contribution of UGT1A1 promoter mutations to neonatal jaundice, we determined the genotypes of c.-3279T>G, c.-3156G>A, and A(TA)7TAA in Malay infants with neonatal jaundice (patients) and in infants without neonatal jaundice (controls). In our population study, only c.-3279T>G was associated with neonatal jaundice. The genotype distributions between both groups were significantly different (p = 0.003): the frequency of homozygosity for c.-3279G was much higher in patients than those in controls. Allele frequency of c.-3279G was significantly higher in patients than those in controls (p = 0.006). We then investigated changes in transcriptional activity because of c.-3279T>G. Luciferase reporter assay in HepG2 cells demonstrated that transcriptional activity of the c.-3279G allele was significantly lower than that of the c.-3279T allele in both the absence and presence of bilirubin. Luciferase reporter assay in COS-7 cells elucidated that c.-3279T>G modified the synergistic effects of the nuclear factors associated with transcriptional machinery. In conclusion, the c.-3279T>G mutation in the UGT1A1 promoter is a genetic risk factor for neonatal jaundice.

We introduce a chip-compatible scheme for the label-free detection of proteins in real-time that is based on the electrically driven conformation switching of DNA oligonucleotides on metal surfaces. The switching behavior is a sensitive indicator for the specific recognition of IgG antibodies and antibody fragments, which can be detected in quantities of less than 10(-18) mol on the sensor surface. Moreover, we show how the dynamics of the induced molecular motion can be monitored by measuring the high-frequency switching response. When proteins bind to the layer, the increase in hydrodynamic drag slows the switching dynamics, which allows us to determine the size of the captured proteins. We demonstrate the identification of different antibody fragments by means of their kinetic fingerprint. The switchDNA method represents a generic approach to simultaneously detect and size target molecules using a single analytical platform.

Nearly background free 1.5-μm single-photon source has been demonstrated using quasiresonant pulsed excitation. We performed a micro-photoluminescence excitation together with photon-correlation experiments, and then we compared photon statistics in nonresonant and quasiresonant excitation case. When we tuned the pump laser to the quasiresonant state which is 18.6 meV higher than the ground state excitonic transmission, almost background-free luminescence was found at 1524.3 nm. The second-order correlation function at time delay of zero, g(2)(0), was reduced to 0.017 when we carefully estimated noise contributions of after-pulses and dark counts in InGaAs APD detectors. This result opens up the possibility of promoting high quality single-photon source at telecommunication wavelength. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The simian virus 40 (SV40) particle is mainly composed of the major capsid protein termed VP1. VP1 self-assembles into virus-like particles (VLPs) of approximately 40 nm in diameter when over-expressed in bacteria or in insect cells, but purified VP1 does not form such a structure under physiological conditions, and thus, the mechanism of VP1 assembly is not well understood. Using a highly purified VP1 assembly/disassembly system in vitro, here we provide evidence that DNA is a factor that contributes to VP1 assembly into 40-nm spherical particles. At pH 5, for example, VP1 preferentially assembles into 40-nm particles in the presence of DNA, whereas VP1 assembles into tubular structures in the absence of DNA. Electron microscopic observations revealed that the concentration of DNA and its length are important for the formation of 40-nm particles. In addition, sucrose gradient sedimentation analysis and DNase I-sensitivity assays indicated that DNA of up to 2,000 bp is packaged into the 40-nm particles under the conditions examined. We propose that DNA may facilitate the formation of 40-nm spherical particles by acting as a scaffold that increases the local concentration of VP1 and/or by acting as an allosteric effector that alters the structure of VP1.

Lysophosphatidylcholine (LPC) has various stimulatory effects on many types of immune cells. The purpose of our study was to characterize blood LPC levels and to determine the composition of LPC molecular species (LPCs) in the neonatal period. Thirty-six neonates were enrolled in this study and then grouped according to birth-weight as follows: non-very low birth weight (NVLBW); >or=1,500 g (n=17), and very low birth weight (VLBW)

For non-tar anticorrosive polyurethane coatings, polyurethane containing phenolic additives (i.e., phenol, styrene adducts with phenol ([St]n—Ph), and indene adducts with phenol ([In]n—Ph)) are prepared and the effusion properties are investigated. As an index on the effusion, the weight change of the polyurethane sheets soaked in water as a function of the soaking time and total organic carbon (TOC) in the water used for the soaking tests are measured. Only the weight of the polyurethane sheet containing [In]n—Ph did not decrease during the soaking test and the TOC was the least. Furthermore, the properties of the phenolic additives plasticizers or `antiplasticizer' are investigated. Although the density and the coefficient of thermal expansion of polyurethane containing [In]n—Ph are increased, since the tensile strength decreased and the elongation increased, [In]n—Ph will be regarded as a plasticizer rather than `antiplasticizer'.

Virus-like particles (VLPs), a promising next-generation drug delivery vehicle, can be formed in vitro using a recombinant viral capsid protein VP1 from SV40. Seventy-two VP1 pentamers interconnect to form the T = 7d lattice of SV40 capsids, through three types of C-terminal interactions, alpha-alpha'-alpha'', beta-beta' and gamma-gamma. These appear to require VP1 conformational switch, which involve in particular the region from amino acids 301-312 (herein Region I). Here we show that progressive deletions from the C-terminus of VP1, up to 34 amino acids, cause size and shape variations in the resulting VLPs, including tubular formation, whereas deletions beyond 34 amino acids simply blocked VP1 self-assembly. Mutants carrying in Region I point mutations predicted to disrupt alpha-alpha'-alpha''-type and/or beta-beta'-type interactions formed small VLPs resembling T = 1 symmetry. Chimeric VP1, in which Region I of SV40 VP1 was substituted with the homologous region from VP1 of other polyomaviruses, assembled only into small VLPs. Together, our results show the importance of the integrity of VP1 C-terminal region and the specific amino acid sequences within Region I in the assembly of normal VLPs. By understanding how to alter VLP sizes and shapes contributes to the development of drug delivery systems using VLPs.

We propose a new approach to fabricating carbon nanotube (CNT) via interconnects for future LSIs, which uses preformed catalyst nanoparticles to grow the CNTs. A newly designed impactor provided size-classified catalyst particles. For the new approach, we employ a TiN contact layer which is more resistant to oxidation and enables us to form a lower resistance ohmic contact between CNTs and wiring layers. The resultant CNT–via resistance was 0.59 Ω for 2-µm vias, which is the smallest ever reported. We also study the CNT nucleation process using molecular dynamics and discuss how to remove amorphous carbon from the nucleation process. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We established an improved method for quantification of phosphatidylcholine (PC) and lysophosphatidylcholine (LPC) molecular species in neonatal serum using high-performance liquid chromatography coupled tandem mass spectrometry (LC-MS/MS). A multiple reaction monitoring (MRM) mode of positive ionization for MS/MS was used. The method involved purification of phospholipids by solid phase extraction (SPE) from a 20-microl minimum specimen of serum. The assayed values of authentic 16:0-LPC and 18:0-LPC showed a linear response, and our quantitative results showed high precision for the all species of PC and LPC. Then, we quantified PC and LPC in adult and neonatal serum and compared them. Day 0-1 neonatal serum 16:0-, 18:0-, 18:1-, 18:2-LPC levels were significantly lower than adult ones. All species LPC levels in the day 0-1 neonates were significantly lower than day 4-8 neonates. Day 0-1 neonatal serum 16:0/18:2-, 18:0/18:2-PC levels were significantly lower than adult ones. Our method is advantageous for precise assessments of the relationships between PCs/LPCs levels and neonatal infectious diseases.

We report on the electrical manipulation of single- and double-stranded oligodeoxynucleotides that are end tethered to gold surfaces in electrolyte solution. The response to alternating repulsive and attractive electric surface fields is studied by time-resolved fluorescence measurements, revealing markedly distinct dynamics for the flexible single-stranded and stiff double-stranded DNA, respectively. Hydrodynamic simulations rationalize this finding and disclose two different kinetic mechanisms: stiff polymers undergo rotation around the anchoring pivot point; flexible polymers, on the other hand, are pulled onto the attracting surface segment by segment.

Low density InAs/GaAs quantum dots (QDs) can be formed by postgrowth annealing of an InAs wetting layer thinner than the critical thickness corresponding to conventional transition from two- to three- dimensional (2D–3D) growth modes. Using real-time reflection high-energy-electron diffraction, the time evolution of total QD volume is analyzed. Based on a mean-field theory [Phys. Rev. Lett. 79 (1997) 897], the initially increasing and finally saturating QD volume is simply and well explained by QD nucleation from precursors. It is suggested that precursors start to grow at an exponential rate well before the 2D–3D growth mode transition, and are responsible for the usually observed significant mass transport from a wetting layer to QDs in conventional QD growth.

The properties of polyurethane containing five kinds of model phenolic additives were investigated. The IR spectra of polyurethane containing phenolic additives indicated that the phenolic additives reacted with isocyanate groups in a polyisocyanate compound. For an index of anticorrosion, the tensile adhesion strength was measured for polyurethane coatings with phenolic additives on steel plates treated with the salt-water spraying test for 3000 h. It was found that there was a relationship between the tensile adhesion strength of polyurethane and the density. We considered the reason to be that the increase in density (i.e., a reduction in free volume) should provide a route to reduce salt-water access to an adhesive bond. The increase in density was explained by the term antiplasticizers, which means that the phenolic additives reduce the free volume that is available for molecular motion in the stiff chain of polyurethane. In the polyurethanes with every phenolic additive, the elongation was increased, the moduli were decreased, the storage modulus was decreased, and the coefficient of thermal expansion was increased. These phenomena are the characteristics of plasticizers. Thus, the phenolic additives have both the character of antiplasticizers and plasticizers, but the polyurethane with phenolic additives had more characteristics of plasticizers than those of antiplasticizers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2099–2106, 2006

In order to study the effects of coal tar components on the adhesion strength of a heavy duty anticorrosive coating formed with tar-urethane resin on a steel plate, polyurethane coatings that were compounded with 15 kinds of polycyclic aromatic compounds as model coal tar components were prepared. In the model coal tar components, naphthalene, quinoline, 2-naphthol, and phenanthrene showed good compatibility with polyurethane. To test their heavy duty anticorrosive properties, tensile adhesion strength of the cured coatings prepared with the compatible model coal tar components was measured, and the change in tensile adhesion strength as a function of time during salt-water spray treatment was measured. We found that the systems compounded with naphthalene, 2-naphthol, and phenanthrene showed good properties in an ordinary state for adhesion strength. However, only the system with 2-naphthol was found to have good properties in the change of tensile adhesion strength as a function of time during salt-water spray treatment. The curing time of the system with 2-naphthol was slower than that of the others, i.e., we found an inverse proportion between curing speed and adhesion durability. We also measured the dynamic viscoelasticity of cured coatings. We found that a tan δ curve of the system with 2-naphthol shifted towards a low temperature side and the tan δ at the temperature at which adhesion strength was measured was larger than that of the others. We hypothesized that the reason for the tan δ shift was a result of the decrease in crosslinking density because 2-naphthol partially capped the isocyanate group. Considering these results, we hypothesized that one of the reasons why the adhesion properties of the system with 2-naphthol had improved was due to the increase of tan δ.

We report on the dynamic control over the orientation of short oligonucleotide strands which are tethered to gold surfaces in electrolyte solution. By applying alternating electrical bias potentials to the supporting electrodes we are able to induce a switching of the layer conformation between a “lying” and a “standing” state, simultaneously monitored in a contactless mode by fluorescence techniques. We demonstrate that our electrooptical experiments allow for an in-depth investigation of the intriguing molecular dynamics of DNA at surfaces and, moreover, how the dynamic response of these switchable biomolecular layers opens new prospects in label-free biosensing.

The Fe/Ti catalyst system that was recently found to be effective for the growth of dense carbon nanotube (CNT) forests was studied using hard x-ray photoemission spectroscopy (HAXPES). It was previously found that the Ti support layer was partially oxidized at room temperature (RT) and absorbed oxygen from the Fe overlayer at higher temperatures, which gave rise to the dense CNT forest growth. The aim of the present study was to elucidate the reason for the initial oxidation of the Ti layer at RT, which remained unclear from the results of the previous study. The control of the initial Ti oxidation is important because it could affect the reduction and activation of the Fe layer at higher temperatures. Depth-dependent HAXPES measurements using different x-ray incidence angles revealed that the degree of oxidation of the 1-nm-thick Ti layer in a sample that had been aged at RT for approximately three months varied depending on the depth. This suggests that oxidation of the Ti layer proceeded after the Fe/...

We fabricated sub-10-nm-wide intercalated multi-layer graphene (MLG) interconnects and demonstrated a resistivity lower than that of cupper (Cu) interconnects with similar dimensions. The high-quality MLG was synthesized epitaxially by chemical vapor deposition on an epitaxial cobalt film, and intercalated with FeCl 3 . After narrowing down the width to 8 nm by electron beam lithography, the 8-nm-wide intercalated MLG exhibited a resistivity of 3.2 µΩcm, which is predicted to be lower than that of Cu interconnects with the same dimensions. Our results show that intercalated MLG is really promising for future LSI interconnects.

We have developed a novel process, the implantation of carbon nanotubes (CNTs) into holes like plugs, vias, and through-silicon vias (TSVs) for the first time. The developed low-temperature process is suitable for back-end-of-line (BEOL) processes of LSI. With this approach, we can use high-quality CNTs grown at high temperature on a different substrate and densify CNTs. Consequently, the implanted CNT plugs had a resistance one order of magnitude lower than the directly grown CNT plugs. In addition, we successfully integrated the implanted CNT plug with transferred multilayer graphene (MLG) wires for all carbon interconnects.

Direct tunneling memory (DTM) with nano-scale gate oxide accomplished low-voltage operation and full compatible process with MOSFET. DTM has a leakage stop barrier and sidewall control gate (CG) which prevent the overlap between a floating gate (FG) and source/drain (SD) extensions. In this work, improved DTM structure overcomes the first demonstration. To design DTM, we also developed a new simulator which considers direct tunneling phenomena and quantum effect at the oxide interface. The simulation shows that DTM has sufficient tolerance against oxide thickness (Tox) fluctuations.

A transistor and memory operation of a new AlGaAs/InGaAs heterojunction field-effect transistor (HFET) in a tetrahedral-shaped recess (TSR) on the [111]B GaAs substrate was investigated at a temperature up to 120 K. The TSR-FET memory has a channel on the [111]A side surfaces of the recess and a single floating quantum dot (QD) gate at the bottom. Owing to the particular shape of the TSR structure, the charge in the floating QD gate can effectively modulate the channel current. We found a clear hysteresis in the current-voltage (I-V) characteristics with an abrupt increase and decrease in the current at the subthreshold gate bias region. Random telegraph signals with a constant amplitude of about 70 nA were also observed in the memory retention characteristics. These phenomena were considered to be attributed to the current modulation by hole charging/discharging in the QD.

We studied InAs self-assembled island formation as a function of the growth rate and examined the effects of overgrown layers on the light emission features. The InAs islands were grown by a conventional molecular beam epitaxy on GaAs. We found that the island size and density strongly depended on the growth rate. With a reduction in the growth rate, the island size increased and the light emission wavelength correspondingly shifted to the longer side. The emission wavelength reached 1.3 μm when the growth-rate was reduced to 2×10 −3 monolayer (ML)/s, but the island density decreased (5×10 9 cm −2 ). We also confirmed that the emission wavelength red-shifted when islands were covered by InGaAs alloys, depending on both the thickness and In composition. Using a combined method, growing islands at a growth rate in the middle range and embedding islands with InGaAs layers, we obtained relatively high density islands with a light emission at 1.3 μm. We confirmed room-temperature lasing from these quantum dots with a threshold current of 8 mA under continuous wave conditions.

The solvent effects on the photosensitized charge separation using partially quaternized poly(1-vinylimidazole)-bound ruthenium(II) complexes (RuQPIm), in which bis(2,2′-bipyridine)ruthenium(II) complexes are coordinated to the imidazolyl residues on the poly(1-vinylimidazole) partially quaternized by 1-bromohexadecane and the degree of quaternization is 19 (RuQPIm-19) and 44 (RuQPIm-44) molar percentage, have been investigated in methanol and methanol–NMF (NMF: N -methylformamide). These systems consist of RuQPIm-19 and RuQPIm-44 as photosensitizers, 1,1′-dimethyl-4,4′-bipyridinium dication (MV 2+ ) and 1,1′-didodecyl-4,4′-bipyridinium dication (C 12 V 2+ ) as electron acceptors, and triethanolamine (TEOA) as a sacrificial donor. The addition of NMF mainly affect the forward and back reactions in the charge separation reactions. In RuQPIm-19 systems, the reaction proceeds through an interactive process, which is through the viologen having π–π interaction for MV 2+ and van der Waals interaction for C 12 V 2+ . In contrast, the reaction proceeds through a direct process by MV 2+ having no interaction and through an interactive process by C 12 V 2+ undergoing van der Waals interaction with the polymer for RuQPIm-44 systems. For MV 2+ , the rates of MV ·+ formation increased, although the quenching efficiency decreased with increasing NMF content for RuQPIm-19 and RuQPIm-44. These results are attributed to stabilization of MV ·+ species by π–π interaction for RuQPIm-19 and steric repulsion between MV ·+ species and RuQPIm-44; namely, the restriction of the back reactions by these effects. In contrast, for C 12 V 2+ , the rates of C 12 V ·+ formation decreased and the quenching efficiency increased with the addition of NMF. These are attributed to that the addition of NMF increases the van der Waals interaction of the C 12 V 2+ with these polymers and the diffusion of the C 12 V ·+ species into the bulk solution; namely, the back reaction is accelerated. Furthermore, it is suggested that the conformational changes in these polymers contribute to the charge separation reaction.

Two partially quaternized poly(1-vinylimidazole)-bound ruthenium(II) complexes (RuQPIm), in which bis(2,2′-bipyridine)ruthenium(II) complexes are coordinated to the imidazolyl residues on partially quaternized poly(1-vinylimidazole) and the degree of quaternization is 19 (RuQPIm-19) and 44 (RuQPIm-44) molar percentage, have been prepared. The solvent effect on quenching of RuQPIm with alkylviologens have been investigated in methanol and methanol–NMF (NMF, N-methylformamide). This system consists of RuQPIm-19 and RuQPIm-44 as photosensitizers, and 1,1′-dimethyl-4,4′-bipyridinium dication (MV2+) and 1,1′-didodecyl-4,4′-bipyridinium dication (C12V2+) as quenchers. In MV2+, with addition of NMF, the Stern–Volmer plot changed from an upward deviating curve to a straight line for RuQPIm-19, while they gave all straight lines for RuQPIm-44. The quenching efficiency decreased with increasing NMF content, and, at high NMF content, became almost the same for both systems. These results indicated that the reaction mechanism of quenching was varied by NMF for RuQPIm-19, but not for RuQPIm-44. In C12V2+, the Stern–Volmer plots gave the upward deviating curves regardless of NMF for RuQPIm-19, and they changed from upward to downward deviating curves with addition of NMF for RuQPIm-44. Furthermore, the quenching efficiency decreased up to NMF content of ca. 20%, and then increased above it. The facts suggested that the quenching reaction was affected by not only π–π interaction and van der Waals one but also shrinking of polymer domain.

The acetonitrile effects on the quenching and photosensitized charge separation using two partially quaternized poly(1-vinylimidazole)-bound ruthenium(II) complexes, RuQPIm-19 and RuQPIm-44, wherein the numbers represent the degree of quaternization in molar percentage, have been investigated. The systems consist of RuQPIm-19 and RuQPIm-44 as photosensitizers, 1,1'-dimethyl-4,4'-bipyridinium (MV 2+ ) and 1,1'-didodecyl-4,4'-bipyridinium (C 12 V 2+ ) dications as electron acceptors (quenchers). and triethanolamine (TEOA) as a sacrificial electron donor. The photosensitized charge separation reaction proceeds through two processes, an interactive process and a direct process, i.e., the viologen is undergoing an interaction with these polymers and no interaction, respectively. The charge separation through the interactive process is less effective than that through the direct process, because the reaction through the interactive process is effective for both the forward and the back reactions. With the addition of acetonitrile, the rates of viologen radical formation decrease for RuQPIm-19 and RuQPIm-44, while the quenching efficiency decreases for RuQPIm-19 and increases for RuQPIm-44. In MV 2+ , the acetonitrile effect contributes to the interactive and direct processes for RuQPIm-19, while it contributes to only the direct process for RuQPIm-44, particularly the forward reaction for RuQPIm-19 and the back reaction for RuQPlm-44. In C 12 V 2+ , the interactive process through which the C 12 V 2+ increases, leading to a decrease in the rates for viologen radical formation. Furthermore, these results indicate that the conformational changes in these polymers play an important role in the charge separation reactions.

We have developed a simple technique for fabricating Sn nanocrystals in thin thermally grown SiO2 layers using low energy ion implantation followed by thermal annealing. The formed Sn nanocrystals have excellent size and depth uniformity. Their average diameter is 4.2 nm with a standard deviation of 1.0 nm. Our experimental results clearly reveal that a stable depth of Sn exists in the SiO2 layer at about 2 nm from the SiO2/Si interface. Most of the Sn nanocrystals reside near this stable depth. The I–V characteristics of the diode structure show a clear Coulomb blockade region of 0.12 V and a Coulomb staircase at 4.2 K. A Coulomb blockade region around 0 V was observed until reaching a temperature of 77 K. The features of these nanocrystals will open up new possibilities for the creation of novel devices.

Novel InGaAs quantum dot (QD) structures were fabricated in tetrahedral-shaped recesses (TSRs) formed on a GaAs (111)B substrate using low-pressure metalorganic chemical vapor deposition (MOCVD). The dots were formed in a self-forming manner at the bottom of TSRs due to the compositional nonuniformity of InGaAs grown inside the TSRs. To confirm directly zero-dimensional carrier confinement, magneto-photoluminescence (PL) measurements were performed for several InGaAs TSR-QDs under pulsed high magnetic fields in both Faraday and Voigt configurations. The diamagnetic shifts of QDs were clearly suppressed compared to the corresponding InGaAs quantum wells formed at the TSR sidewalls. The typical deduced Bohr radius from the hydrogen-like exciton model clearly proves a zero-dimensional carrier confinement into the TSR-QD. Moreover, the changes in the strength and anisotropy of the QDs' confinement potential obtained from the magneto-PL results were consistent with the intentional change in the design of the TSR-QDs. Through these studies, we clarified that it is possible to control the carrier confinement potential of TSR-QDs by independently changing the In-content and the thickness of InGaAs during MOCVD growth.

InGaAs/GaAs quantum dot (QD) structures grown in tetrahedral-shaped recesses (TSR) etched into GaAs (111)B substrates are studied by means of cathodoluminescence (CL). Two main features are observed in the CL spectra. The lower energetic peak can be assigned to QDs in the bottom of the TSRs, while the higher energetic one corresponds to the quantum wells (QWs) formed at the sides of the TSRs. This can be confirmed by spatially resolved CL imaging. The behavior of QD and QW luminescence is studied by temperature and electron beam intensity dependence of CL. We will show that the formation of the QDs is strongly dependent on the size and the spacing of the TSRs.

We study the coadsorption of mercaptohexanol onto preimmobilized oligonucleotide layers on gold. Monitoring the position of the DNA relative to the surface by optical means directly shows the mercaptohexanol-induced desorption of DNA and the reorientation of surface-tethered strands in situ and in real time. By simultaneously recording the electrochemical electrode potential, we are able to demonstrate that changes in the layer conformation are predominantly of electrostatic origin and can be reversed by applying external bias to the substrate.

We investigated non-resonant phonon-assisted tunnelling in an InGaAs/InAlAs triple barrier tunnelling diode in the presence of high magnetic fields up to 40 T in the current direction. We observe quenching of the non-resonant valley current and narrow band GaAs-like and AlAs-like longitudinal optical (LO) phonon peaks related to the phonon bottleneck effect. The peak-to-valley ratio of the device increases significantly up to magnetic fields of 12 T. LO-phonon peaks give information about the electron - LO-phonon coupling strength in the well and the barrier layers.

Closely stacked Stranski-Krastanow (SK) growth islands were investigated. InAs islands of nominal 1.8 monolayer thickness were grown periodically with GaAs intermediate layers of less than 3 nm by molecular beam epitaxy. Reflection high-energy electron diffraction and atomic force microscopy revealed that SK growth islands were formed even with stacked intervals of 2 nm, but the upper island size expanded slightly as the number of stacked layers increased. Transmission electron microscopy revealed that upper islands grew closely just on the lower islands aligning vertically on the first layer islands. Drastic decrease in photoluminescence full-width at half-maximum less than 30 meV was obtained from this structure.

Metallopolymers in which bis(2,2'-bipyridine)ruthenium(II) complexes are coordinated to imidazolyl residues on partially quaternized poly(1-vinylimidazole) having different degree of quaternization (RuQPIm) were synthesized. The luminescence quenching of the photoexcited RuQPIms with various alkylviologens having different length of alkyl group was investigated in MeOH. In quenching of RuQPIm with methylviologen (MV 2+ ), the efficiency of quenching decreases with increasing degree of quaternization. This was attributed to the electrostatic repulsion between the MV 2+ species and the quaternized imidazolium residue on the polymer backbone and steric hindrance of the alkyl side chain. Furthermore, the efficiency of quenching depends on the length of the alkyl group in viologen. These results suggest that the alkyl side chain on the polymer backbone exerts steric hindrance at low degree of quaternization and van der Waals interaction at high degree of quaternization.

本論文は，温排水や下水等の汚濁熱源からの熱抽出を液液直接接触熱交換法にて行う際の熱媒体として有望なフッ素系不活性液体混合物に関する諸物性の測定法とその測定結果について報告するものである．フッ素系不活性液体混合物の物性である密度，動粘度，水との界面張力，比熱，熱伝導率のそれぞれについて，温度T＝273.15～323.15Kの広範な温度領域においての測定を行った．また，各物性の温度依存性に関する関係式の誘導を行った．

Objective: The objective was to investigate the efficacy and tolerability of combined therapy with paclitaxel and carboplatin (TC) in patients with advanced urothelial carcinoma after the failure of first-line chemotherapy with gemcitabine and cisplatin (GC). Patients and Methods: This was a retrospective study including a total of 16 patients with advanced urothelial carcinoma who showed evidence of progressive and/or recurrent disease after first-line therapy with GC and subsequently received second-line chemotherapy consisting of paclitaxel (175 mg/m2) and carboplatin (area under the curve 5). TC therapy was repeated every 3 weeks and was continued until disease progression or intolerable toxicity was observed. Results: The baseline patient characteristics were rather favorable; only 3 of 16 patients had liver metastases and 7 patients had an Eastern Cooperative Oncology Group performance status of 0. Of these, response to TC therapy was achieved in 5 (31.3%), including 2 with complete and 3 with partial response. The median progression-free and overall survival times in the 16 patients were 7.9 and 17.3 months, respectively. Conclusions: TC therapy appeared to show modest activity with acceptable tolerability in patients refractory to GC therapy; therefore, TC chemotherapy might be considered as an alternative option as a second-line regimen for advanced urothelial carcinoma following GC therapy.