Surface layer characteristics of ion-implanted metals

Recently ion implantation into metals has been carried out mainly for fundamental studies of non-electronic properties in surface layers such as friction, wear, corrosion etc. Many results have shown that the technique is useful for the improvement of surface layer properties such as wear and corrosion resistance. In this report we describe recent results obtained with the implantation process and the mechanical and chemical properties of implanted iron or iron-based alloys.     

Capillary electrophoresis of sialic acid-containing glycoprotein. Effect of the heterogeneity of carbohydrate chains on glycoform separation using an alpha1-acid glycoprotein as a model

alpha1-Acid glycoprotein (AGP) showed multiple peaks on separation using capillary electrophoresis in a chemically modified capillary with dimethylpolysiloxane at slightly acidic conditions. We analyzed glycoforms of AGP species after separation by ion-exchange chromatography, Con A affinity chromatography, and Cu(II)-chelating affinity chromatography. The AGP species thus obtained were digested with N-glycosidase F, and the released carbohydrate chains were analyzed by high-performance liquid chromatography after labeling with 3-aminobenzoic acid. The results afforded basic information on the contribution of carbohydrate chains to the separation mechanism of glycoforms of AGP by capillary electrophoresis. In addition, we describe an easy method for AGP analysis in serum samples using the electrokinetic injection.     

Preparation and Thermoelectric Properties of LaGd<Subscript>1+<Emphasis Type="Italic">x</Emphasis></Subscript>S<Subscript>3</Subscript> and SmGd<Subscript>1+<Emphasis Type="Italic">x</Emphasis></Subscript>S<Subscript>3</Subscript>

Thermoelectric materials are attractive since they can recover waste heat directly in the form of electricity. In this study, the thermoelectric properties of ternary rare-earth sulfides LaGd_1+x S₃ (x = 0.00 to 0.03) and SmGd_1+x S₃ (x = 0.00 to 0.06) were investigated over the temperature range of 300 K to 953 K. These sulfides were prepared by CS₂ sulfurization, and samples were consolidated by pressure-assisted sintering to obtain dense compacts. The sintered compacts of LaGd_1+x S₃ were n-type metal-like conductors with a thermal conductivity of less than 1.7 W K⁻¹ m⁻¹. Their thermoelectric figure of merit ZT was improved by tuning the chemical composition (self-doping). The optimized ZT value of 0.4 was obtained in LaGd_1.02S₃ at 953 K. The sintered compacts of SmGd_1+x S₃ were n-type hopping conductors with a thermal conductivity of less than 0.8 W K⁻¹ m⁻¹. Their ZT value increased significantly with temperature. In SmGd_1+x S₃, the ZT value of 0.3 was attained at 953 K.     

Photostable Iodinated Silica/Porphyrin Hybrid Nanoparticles with Heavy‐Atom Effect for Wide‐Field Photodynamic/Photothermal Therapy Using Single Light Source

Physical therapies including photodynamic therapy (PDT) and photothermal therapy (PTT) can be effective against diseases that are resistant to chemotherapy and remain as incurable malignancies (for example, multiple myeloma). In this study, to enhance the treatment efficacy for multiple myeloma using the synergetic effect brought about by combining PDT and PTT, iodinated silica/porphyrin hybrid nanoparticles (ISP HNPs) with high photostability are developed. They can generate both ¹O₂ and heat with irradiation from a light‐emitting diode (LED), acting as photosensitizers for PDT/PTT combination treatment. ISP HNPs exhibit the external heavy atom effect, which significantly improves both the quantum yield for ¹O₂ generation and the light‐to‐heat conversion efficiency. The in vivo fluorescence imaging demonstrates that ISP HNPs, modified with folic acid and polyethylene glycol (FA‐PEG‐ISP HNPs), locally accumulate in the tumor after 18 h of their intravenous injection into tumor‐bearing mice. The LED irradiation on the tumor area of the mice injected with FA‐PEG‐ISP HNPs causes necrosis of the tumor tissues, resulting in the inhibition of tumor growth and an improvement in the survival rate.     

Highly available network design and resource management of SINET4

The Japanese academic backbone network has been providing a variety of multilayer network services to support a wide range of research and education activities for more than 700 universities and research institutions. The new version, called SINET4, was launched in 2011 in order to enhance the service availability and the network bandwidth as well as to expand the service menu. Its enhanced service availability was unexpectedly verified by the disastrous March 11 Great East Japan Earthquake, when the network managed not to stop service operation even after the earthquake. This paper describes the design and implementation of SINET4 in terms of multiple service provision, network resource control and management, and high reliability from physical level to network management level. The impacts of the huge earthquake are also reported.     

Removal of radioactive iodine and cesium in water purification processes after an explosion at a nuclear power plant due to the Great East Japan Earthquake

The presence of radionuclides at five water purification plants was investigated after an explosion at a nuclear power plant hit by the Great East Japan Earthquake on 11 March 2011. Radioactive iodine (¹³¹I) and cesium (¹³⁴Cs and ¹³⁷Cs) were detected in raw water in Fukushima and neighboring prefectures. ¹³¹I was not removed by coagulation-flocculation-sedimentation. ¹³¹I was removed by granular activated carbon (GAC) and powdered activated carbon (PAC) at a level of about 30%-40%, although ¹³¹I was not removed in some cases. This was also confirmed by laboratory-scale experiments using PAC. The removal percentages of ¹³¹I in river and pond waters by 25 mg dry/L of PAC increased from 36% to 59% and from 41% to 48%, respectively, with chlorine dosing before PAC. ¹³⁴Cs and ¹³⁷Cs were effectively removed by coagulation at both a water purification plant and in laboratory-scale experiments when turbidity was relatively high. In contrast, ¹³⁴Cs and ¹³⁷Cs in pond water with low turbidity were not removed by coagulation. This was because ¹³⁴Cs and ¹³⁷Cs in river water were present mainly in particulate form, while in pond water they were present mainly as cesium ions (¹³⁴Cs⁺ and ¹³⁷Cs⁺). However, the removal of ¹³⁴Cs and ¹³⁷Cs in pond water by coagulation increased markedly when ¹³⁴Cs and ¹³⁷Cs were mixed with sediment 24 h before coagulation.     

Expression of neurofibromatosis 2 protein in human brain tumors: an immunohistochemical study

Examining damage (inactivation) of antioxidant enzymes in the cells and the pattern of recovery after a single UV exposure might be a useful method for analyzing the mechanisms of chronic UV irradiation, because chronic UV irradiation means repeated single exposures. We irradiated human skin fibroblasts with a single exposure to UVA (1, 6 or 12 J/cm2) and examined the time course of changes in antioxidant enzymes over several days. Only catalase activity was inactivated at the end of the irradiation (66% for 6 J/cm2, 53% for 12 J/cm2), recovering by day 5. Superoxide dismutase (SOD) activity decreased on day 3 (63% for 6 J/cm2, 72% for 12 J/cm2), and recovered on day 5, although it was not changed at the end of exposure. The activities of glutathione peroxidase (GSH-Px) and glutathione reductase (GR) were nearly unchanged by irradiation. If repeated UV exposures occur before the inactivated enzyme activities recover, cellular damage will be significant due to the lowered antioxidant defense system. We examined the rates of synthesis and degradation of catalase in response to UVA irradiation. Both synthesis and degradation rates were changed by irradiation. These data indicate that catalase activity was still low on day 2 due to the existence of inactivated catalase produced at the end of UV irradiation, and catalase activities recovered by day 5 due to a significant increase in the synthesis rate. To elucidate the role of bound NADPH in catalase in response to UV irradiation, we measured the NADPH released from catalase after UVA irradiation using bovine liver catalase. UVA irradiation caused a release of NADPH from catalase (25% for 12 J/cm2), but this was not directly related to the inactivation of catalase.     

Enhancement of the oral bioavailability of phenytoin by N-acetylation and absorptive characteristics

To improve the absorbability of phenytoin (DPH), a prodrug, N-acetyl-DPH (EDPH), was synthesized, and the absorptive characteristics and pharmacokinetics of the prodrug were evaluated in rats. EDPH was rapidly hydrolyzed to DPH in the intestinal fluid and the mucosa (rate constant, 0.055 and 0.169 min(-1), respectively). The plasma concentrations of DPH after intravenous dosing of EDPH declined in a biexponential manner, although two different elimination patterns were observed in these rats. When dosed orally (25 mg/kg, DPH equivalent), the plasma levels of DPH converted from the prodrug were significantly higher and more sustained than those after DPH alone, giving bioavailability 11.4 (rapid decay) and 9.1 times (slow decay) as high, respectively, as that after DPH alone. The concentrations of DPH distributed into the mucosa of the duodenum and jejunum 1 and 5 h after oral dosing of EDPH were significantly higher than those after DPH alone. The prodrug and DPH converted from the prodrug dissolved 2-4 fold more than DPH alone in bile salt solution and bile salt-oleic acid mixed micelles, indicating the increased solubility of the prodrug in the intestinal fluid. It is concluded from the data that such high solubility of EDPH enhanced the intestinal absorption of the prodrug, part of which would be absorbed in the amide form, and thus gave the high bioavailability.