Characterization of Scale Formed on the Surfaces of Toilet Bowls

Repeated use of a toilet results in the build-up of a deposit derived from urine and hard water on the surface of the toilet bowl. The hardened mineral scale is difficult to clean completely, especially in the case of deposits under the rim. A number of studies have focused on kidney stones, which are also caused by urine in the urinary tract; little attention, however, has been paid to the detailed composition and structure of the toilet scale. To develop powerful products for removing the toilet scale effectively instead of relying on acid-cleaning and scrubbing, the composition and the accumulation mechanism of the scale must be clarified. Scale samples collected from the bowl surface were characterized by IR, XRF, XRD, ICP–AES, SEM–EDS and HPLC techniques and found to consist mainly of calcium phosphates, struvite, calcium carbonate, uric acid and proteins. After acid treatment of the scale, a film-like structure of protein, produced as a result of the metabolism of bacteria and mold, was left behind. The scale had composite structures that were composed of the inorganic minerals and the organic materials listed above. This structure might be critical to making the scale resistant to removal by acid-containing cleaners.     

Characteristics of SiH4/H2 VHF plasma produced by short gap discharge

A SiH₄/H₂ VHF plasma was produced with the multi rod electrode and the fundamental plasma parameters were examined as a function of pressure and power, where the frequency of the power source was 60 MHz. It was found that the ion saturation current takes a peak at a certain power as well as pressure. These results were discussed from the point of view of electron trapping effect in VHF electric fields. In addition, anomalous reduction of the sheath potential was observed.     

A study of accounting standard-setting using graph theory

The setting of accounting standards is subject to political influences by commercial companies which prepare financial statements. Despite strong objections from them, the Financial Accounting Standards Board (FASB) decided to set conceptual and user-oriented accounting standards on business combinations. The aim of this article is to clarify which groups play a central role using graph theory. These analyses using voice data and data produced from voting behaviors in board meetings reveal that the centrality of the preparers (group) is low, and those of academics (group) and users (group) are high in this project. This result may indicate that there are factors that undermine the power of the preparers in the FASB.     

Crystal Phases Formed in a CaO-Fe2O3 System Under a High Cooling Rate in Air

Metallurgical and Materials Transactions B - A CaO-Fe2O3 system is a fundamental binary system for the iron ore sintering process. Although the basic reactions have been investigated since the...     

Inducible expression system for the marine cyanobacterium Synechococcus sp. strain NKBG 15041c

Cyanobacteria have been recognized as promising host organisms to produce biofuel materials including hydrogen and hydrocarbons due to high biomass productivity and capability of transformation. Metabolic engineering has recently been employed for further enhancement of bioenergy production, while excess fuel materials could give rise to cytotoxicity. Therefore genetic tools are required in order to precisely control the gene expression involved in the fuel production metabolism. Thus far, inducible-expression systems in cyanobacteria have been established mainly in freshwater strains. However there are a few reports with regard to marine strains, which can use vast of ocean for cultivation. In this study, we established a tetracycline-inducible gene expression system in the marine cyanobacterium Synechococcus sp. strain NKBG 15041c. Since tetracycline-inducible system is a non-native regulation, it is expected for inherent metabolisms not to be disrupted. The de novo designed promoter including tetracycline operator elements was inactivated by the repressor protein, and inducer addition successfully initiated target protein expression. This is the first report to demonstrate tetracycline-induction system with strict on/off switching in marine cyanobacteria, and it should be useful for future bioenergy production.     

Three-Dimensional Visualization of Material Flow During Friction Stir Welding of Steel and Aluminum

Material flow is a key phenomenon to obtain sound joints by friction stir welding (FSW), and it is highly dependent of the welded material. It is well known that the optimal FSW condition depends on the welded material. However, the material flow during FSW has not been totally clarified in spite of many researches. Especially, the material flow of steel during FSW is still unclear. It seems difficult to understand the material flow by the traditional method such as the tracer method or observation of the microstructure in the stir zone. Therefore, in this study, the material flow of steel was three dimensionally visualized by x-ray radiography using two pairs of x-ray transmission real-time imaging systems, and was then compared with the material flow of aluminum. The result revealed the effect of the welded material on the material flow during FSW.     

Involvement of Hydrogen Peroxide in Safingol-Induced Endonuclease G-Mediated Apoptosis of Squamous Cell Carcinoma Cells

Safingol, a L-threo-dihydrosphingosine, induced the nuclear translocation of a mitochondrial apoptogenic mediator—endonuclease G (endo G)—and apoptosis of human oral squamous cell carcinoma (SCC) cells. Upstream mediators remain largely unknown. The levels of hydrogen peroxide (H₂O₂) in cultured oral SCC cells were measured. Treatment with safingol increased intracellular H₂O₂ levels but not extracellular H₂O₂ levels, indicating the production of H₂O₂. The cell killing effect of safingol and H₂O₂ was diminished in the presence of reactive oxygen species (ROS) scavenger N-acetyl-L-cysteine (NAC). Dual staining of cells with annexin V and propidium iodide (PI) revealed that apoptotic cell death occurred by treatment with H₂O₂ and safingol. The number of apoptotic cells was reduced in the presence of NAC. In untreated cells, endo G distributed in the cytoplasm and an association of endo G with mitochondria was observed. After treatment with H₂O₂ and safingol, endo G was distributed to the nucleus and cytoplasm, indicating the nuclear translocation of the mitochondrial factor. NAC prevented the increase of apoptotic cells and the translocation of endo G. Knock down of endo G diminished the cell killing effect of H₂O₂ and safingol. These results suggest that H₂O₂ is involved in the endo G-mediated apoptosis of oral SCC cells by safingol.     

Crosslinking Liposomes/Cells Using Cholesteryl Group-Modified Tilapia Gelatin

Cholesteryl group-modified tilapia gelatins (Chol-T-Gltns) with various Chol contents from 3 to 69 mol % per amino group of Gltn were prepared for the assembly of liposomes and cells. Liposomes were physically crosslinked by anchoring Chol groups of Chol-T-Gltns into lipid membranes. The resulting liposome gels were enzymatically degraded by addition of collagenase. Liposome gels prepared using Chol-T-Gltn with high Chol content (69Chol-T-Gltn) showed slower enzymatic degradation when compared with gels prepared using Chol-T-Gltn with low Chol content (3Chol-T-Gltn). The hepatocyte cell line HepG2 showed good assembly properties and no cytotoxic effects after addition of 69Chol-T-Gltns. In addition, the number of HepG2 cells increased with concentration of 69Chol-T-Gltns. Therefore, Chol-T-Gltn, particularly, 69Chol-T-Gltn, can be used as an assembling material for liposomes and various cell types. The resulting organization can be applied to various biomedical fields, such as drug delivery systems, tissue engineering and regenerative medicine.