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In a previous study, we showed that formylmethylflavin (FMF) can bind to cysteine. In this study, FMF was reacted with native peptides (CG and CKLVFF) containing an N-terminal cysteine. The formation of flavin-CG and flavin-CKLVFF was confirmed using HPLC and ESI-MS. Storage of flavin-CKLVFF in DMSO at −30 °C for 7 days resulted in no detectable deposition. In contrast, flavin-CKLVFF formed deposits when stored in water at −30 °C for 1 day, but no deposit was observed in the aqueous solution of flavin-CKLVFF after 7 days storage in the presence of 0.1% Triton X-100.

Using X-ray microdiffraction (XRMD) and transmission electron microscopy (TEM) techniques, we have investigated the microscopic structure of Si(011)/Si(001) direct silicon bonding (DSB) substrates. XRMD was performed to measure the local lattice spacing and tilting in the samples before and after oxide out-diffusion annealing. Diffraction analyses for (022) lattice planes with two orthogonal in-plane directions of X-ray incidence revealed anisotropic domain textures in the Si(011) layer. Such anisotropy was also confirmed by TEM in the morphology at the Si(011)/Si(001) bonded interface. The anisotropic crystallinity is discussed on the basis of interfacial defect structures which are proper to the DSB substrate.

We have investigated using X-ray microdiffraction (XRMD) and transmission electron microscopy (TEM) the microstructures of Direct Silicon Bonding (DSB) substrates which were prepared by bonding a Si(0 1 1) wafer to a Si(0 0 1) wafer. XRMD was performed to measure the local lattice spacing and tilting in the samples before and after the interface oxide out-diffusion annealing. Diffraction analyses for (0 2 2) lattice planes with two orthogonal in-plane directions of X-ray incidence revealed anisotropic domain textures in the Si(0 1 1) layer. Such anisotropy was also confirmed by TEM in the morphology at the Si(0 1 1)/Si(0 0 1) bonded interface. The anisotropic crystallinity is discussed on the basis of interfacial defect structures which are proper to the DSB substrate.

Directly bonded Si(011)/Si(001) substrates were prepared by conventional bonding and grind back methods. The bonding interface structure and crystallinity in the bonded substrate were studied by transmission electron microscopy and X-ray diffraction (XRD). The regular array of dislocations and the undulation were formed in the interface. From XRD analysis, it was confirmed that the crystallinity of the Si(011) layer in the bonded substrate deteriorated in comparison with the bulk Si(011) wafer. We proposed that directly bonded Si substrates with different crystal orientations induced stress at the bonding interface due to misfit bonding, as a result, the Si(011) layer was strained and the undulation was formed at the bonding interface.

We have investigated the crystallinity of compositionally graded SiGe layers of strained Si (s-Si) wafers in the growth direction by irradiating a synchrotron X-ray microbeam with a high parallelism on a cross section of s-Si wafers. As a result, we can confirm the presence of surface parallel SiGe lattice rotation and lattice rotation distribution (LRD). The surface parallel LRD and relaxation ratio of SiGe start to decrease in the depth direction below approximately 3 ?m from the wafer surface. It is inferred that the insufficient relaxation of SiGe near the wafer surface is caused by the characteristics of the free wafer surface. Furthermore, such characteristics are thought to lead to a reduction in LRD near the wafer surface.

As semiconductor devices become progressively smaller, it is important that wafers are fabricated with extremely uniform thicknesses. Although, GCIB technology can be used for corrective etching of Si wafers with high accuracy, an amorphous Si (a-Si) layer is formed in the process by the collision of cluster ions with the Si surface. We have shown that the a-Si layer formed on Si surfaces by Ar-GCIB and SF6-GCIB irradiation disappears completely and atomically smooth surfaces are formed after high-temperature annealing. In this study, the recovery of a surface damaged at various annealing temperatures was investigated in detail by TEM, AFM and SIMS. We found that the disappearance of the a-Si layer occurred by solid phase epitaxy (SPE) from low temperature and atomically smoothing at the surface occur by migration of Si atoms at high-temperature. Moreover, due to Ar-GCIB irradiation, Ar was found in high concentrations in the a-Si layer and crystal defects were formed on the surface after annealing. The Ar concentration on the Si surface could be decreased by irradiating SF6-GCIB after Ar-GCIB irradiation.

To assess the surface reactivity of strained Si wafers, open circuit potential (ocp) measurement and scanning surface potential microscopy (SPoM) were carried out. Surface conditions of the wafers were varied by changing the structure of the wafers, i.e., the Ge content of the SiGe underlayer and the thickness of the strained Si layer. The ocp value of the strained Si was negative compared with that of nonstrained Si, and it shifted in the negative direction with an increase in Ge content of the SiGe layer and/or in the thickness of the strained Si layer, indicating that the degree of strain and/or the density of defects at the Si wafer surface affect its reactivity. In addition, the ocp value shifted in the positive direction to reach the value of the nonstrained Si, possibility due to stress relaxation, when the thickness of strained Si exceeds a certain value, which is expected to be the “critical” thickness. The SPoM analysis confirmed that the negative potential shift takes place locally at the surfa...

A waste-heat transportation system that uses a phase change material (PCM)—the so-called trans-heat (TH) system—is considerably attractive from the viewpoint of saving energy because manufacturing industries such as the steelmaking industry continue to emit high-temperature waste heat. The aim of this paper is to study the feasibility of the TH system from three viewpoints—energy requirement, exergy loss and CO2 emissions—which affect the heat source and heat storage materials in the TH system. The TH system, which recovers waste heat and supplies hot or cold water, is comparatively evaluated under reasonable assumptions such as the temperature of the waste heat is 200°C and that of the supplied water is 50°C or 7°C, the transportation distance is 20 km and the laden weight of the container is 2.4·104 kg (weight of the PCM=1.75·104 kg; weight of the heat transfer oil=2.5·103 kg). The following results are obtained: The latent heat of erythritol supplies the largest amount of heat, 5.31 GJ at 50°C, in the TH systems. For supplying hot water at 50°C, the energy requirement of the TH system with erythritol is 7.7%, exergy loss is 8.1% and CO2 emission is 20.2% as compared to those of the conventional system with kerosene on site. For supplying cold water at 7°C, the energy requirement of the TH system with erythritol is 12.0%, exergy loss is 12.0% and CO2 emission is 26.6% as compared to those of a conventional absorption chiller that uses natural gas as the heat source.

A waste heat transportation system––trans-heat (TH) system––is quite attractive that uses the latent heat of a phase change material (PCM). The purpose of this paper is to study the thermophysical properties of various sugars and sodium acetate trihydrate (SAT) as PCMs for a practical TH system and the heat transfer property between PCM selected and heat transfer oil, by using differential scanning calorimetry (DSC), thermogravimetry-differential thermal analysis (TG-DTA) and a heat storage tube. As a result, erythritol, with a large latent heat of 344 kJ/kg at melting point of 117°C, high decomposition point of 160°C and excellent chemical stability under repeated phase change cycles was found to be the best PCM among them for the practical TH system. In the heat release experiments between liquid erythritol and flowing cold oil, we observed foaming phenomena of encapsulated oil, in which oil droplet was coated by solidification of PCM.

The surface structures of Si (1 0 0) wafers subjected to gas cluster ion beam (GCIB) irradiation have been analyzed by cross-sectional transmission electron microscopy (XTEM) and atomic force microscopy (AFM). GCIB irradiation is a promising technique for both precise surface etching and planarization of Si wafers. However, it is very important to understand the crystalline structure of Si wafers after GCIB irradiation. An Ar-GCIB used for the physically sputtering of Si atoms and a SF 6 -GCIB used for the chemical etching of the Si surface are also analyzed. The GCIB irradiation increases the surface roughness of the wafers, and amorphous Si layers are formed on the wafer surface. However, when the Si wafers are annealed in hydrogen at a high temperature after the GCIB irradiation, the surface roughness decreases to the same level as that before the irradiation. Moreover, the amorphous Si layers disappear completely.

We have investigated dislocation morphology and strain relaxation mechanisms of SiGe and Ge sub-micron wide striped mesa lines patterned on Si(0 0 1) substrates. The patterning of SiGe and Ge layers principally leads to asymmetric elastic strain relaxation. Post-patterning anneal induces 60° dislocation introduction to relax the strain but the narrower the line width the more dominant is the elastic strain relaxation. In the case of 250 nm wide SiGe lines, 60° dislocation introduction along the line is critically suppressed so that asymmetric strain distribution is realized. On the other hand, for the Ge line structure, pre-formed pure edge dislocations elongate along both orthogonal directions at the heterointerface independent of the line geometry even with the line width of 250 nm. Thus strain relaxation occurs symmetrically and rigidly. These results can be explained by deference of the introduction and propagation mechanisms of 60° and pure-edge dislocations.

The deposition of Amyloid beta peptides (Aβ) in the formation of amyloid fibrils is believed to be causally linked to Alzheimer's disease. A short Aβ fragment (KLVFF; Aβ16-20) can bind full-length Aβ. The Aβ recognition peptide including KLVFF was attached with hydrophilic groups, and then the product altered the Aβ aggregation pathways and inhibited Aβ toxicity (Tjernberg, L. O. et al. J. Biol. Chem. 1996, 271, 8545-8548. ). Since flavins is widely known as biological oxidation reagents, the flavin-linked KLVFF is likely to directly hydroxylate aggregated Aβ fibrils and then disrupt the aggregated Aβ fibril. 2-Aminoethanethiol derivatives, such as cysteine, is reacted with aldehydes, and five-membered heterocyclic ring is formed via formation of imine. Since formylmethylflavin (FMF) contains aldehyde group, FMF is likely to bind cysteine. Then, the peptides containing Aβ recognition region and cysteine, such as CKLVFF, also can be attached with FMF to form the flavin-linked KLVFF. The preliminary experiment of this reaction, the reaction between FMF and cysteine, was investigated. FMF (2.84 mg, 10 μmol) was suspended in phosphate buffer (pH 7, 10 ml), and cysteine (2.42 mg, 20 μmol) was added. The suspension was stirred at 65oC for 1h. As a result, FMF was completely reacted, and flavin-linked cystein were detected using HPLC and ESI-MS.

The critical thickness of strained Si (s-Si) grown on Si0.8Ge0.2 by low-pressure chemical vapor deposition (LP-CVD) and the quantitative relationship between s-Si layer thickness and dislocation densities were investigated by etch pit density (EPD) analysis. The obtained results showed that an increase in s-Si layer thickness increases the threading dislocation density (TDD) and misfit dislocation density (MDD) in the s-Si layer grown on the SiGe layer. In this experiment, the critical thickness of the s-Si layer grown on the SiGe layer was between 2 and 5 nm. This value is significantly lower than the critical thickness of Si0.8Ge0.2 on Si obtained on the basis of Matthews' theory (between approximately 10 and 15 nm).

It was found that patterning of Ge and SiGe layers on Si(001) substrates principally leads to the strain anisotropy. The striped mesa structure readily induces elastic relaxation of the strained Ge and SiGe. Furthermore, a clear difference of strain relaxation mechanism depending on the dislocation introduction was confirmed. Introduction of 60deg dislocations is sensitive to the shape of patterned region, resulting in the anisotropic strain. On the other hand, the pure-edge dislocation network explicitly leads to isotropic strain relaxation even in the miniaturized region

Irradiation by a Gas Cluster Ion Beam (GCIB) is a promising technique for precise surface etching and planarization of Si wafers. However, it is very important to understand the crystalline structure of Si wafers after GCIB irradiation. In this study, the near surface structure of a Si (100) wafer was analyzed after GCIB irradiation, using a cross‐sectional transmission electron microscope (XTEM). Ar‐GCIB, that physically sputters Si atoms, and SF6‐GCIB, that chemically etches the Si surface, were both used. After GCIB irradiation, high temperature annealing was performed in a hydrogen atmosphere. From XTEM observations, the surface of a virgin Si wafer exhibited completely crystalline structures, but the existence of an amorphous Si and a transition layer was confirmed after GCIB irradiation. The thickness of amorphous layer was about 30 nm after Ar‐GCIB irradiation at 30 keV. However, a very thin (< 5 nm) layer was observed when 30 keV SF6‐GCIB was used. The thickness of the transition layer was the sam...

We investigated the interface structure of directly bonded Si(011)/Si(001) substrates prepared by conventional bonding and grind-back. The interfacial structure was analyzed by transmission electron microscopy (TEM) and in-plane X-ray diffraction (XRD). The plan-view and cross-sectional TEM observations provided evidence that screw dislocation lines were localized to the interfacial plane and that threading dislocations were absent. Grazing-incidence in-plane XRD analyses confirmed the existence of mosaic structures at the interface. These structures were formed because of the deformation field produced by the screw dislocations. This allowed a high level of crystallinity to be maintained in regions away from the interface in both the Si(011) layer and the Si(001) wafer.

Directly bonded interfaces of hydrophilic and hydrophobic Si(100) wafers were studied from the viewpoint of bonding energy and chemical products as a function of the annealing temperature. The experimental results indicated that for both hydrophilic and hydrophobic Si/Si bonded wafer pairs, the behavior of the bubbles at the bonding interface and the bonding energy were closely related to the behavior of the hydrogen and oxygen atoms at the bonding interface. The bonding mechanisms for both cases have been discussed on the basis of the chemical reactions induced by the annealing temperature.