Modulation of Interparticle Distance in Discrete Gold Nanoparticle Dimers and Trimers by DNA Single‐Base Pairing

Self‐assembled structures of metallic nanoparticles with dynamically changeable interparticle distance hold promise for the regulation of collective physical properties. This paper describes gold nanoparticle dimers and trimers that exhibit spontaneous and reversible changes in interparticle distance. To exploit this property, a gold nanoparticle is modified with precisely one long DNA strand and approximately five short DNA strands. The long DNA serves to align the nanoparticles on a template DNA via hybridization, while the short DNAs function to induce the interparticle distance changes. The obtained dimer and trimer are characterized with gel electrophoresis, dynamic light scattering measurements, and transmission electron microscopy (TEM). When the complementary short DNA is added to form the fully matched duplexes on the particle surface in the presence of MgCl₂, spontaneous reduction of the interparticle distance is observed with TEM and cryo‐electron microscopy. By contrast, when the terminal‐mismatched DNA is added, no structural change occurs under the same conditions. Therefore, the single base pairing/unpairing at the outermost surface of the nanoparticle impacts the interparticle distance. This unique feature could be applied to the regulation of structures and properties of various DNA‐functionalized nanoparticle assemblies.     

Facile and scalable synthesis of a highly hydroxylated water-soluble fullerenol as a single nanoparticle

A water-soluble polyhydroxylated fullerene, i.e. a fullerenol, with 44 hydroxyl groups and 8 secondary bound water molecules, C₆₀(OH)₄₄·8H₂O (estimated average structure), has been synthesized in a facile one step reaction from pristine C₆₀ by hydroxylation with hydrogen peroxide in the presence of a phase-transfer catalyst, tetra-n-butylammonium hydroxide (TBAH), under organic/aqueous bilayer conditions. The fullerenol exhibited high water solubility, up to 64.9 mg/mL, under neutral (pH = 7) conditions. Dynamic light-scattering (DLS) analysis showed a narrow particle size distribution, of 1–2 nm, indicating that the fullerenol had high dispersion properties in water. The results of particle size analyses, which both focused on a single nanoregion and were conducted using a novel induced grating (IG) method and a scanning probe microscope (SPM), were consistent with the DLS results. A plausible reaction mechanism, which includes fullerene oxide intermediates detected by liquid chromatography-mass spectrometry (LC-MS), has been proposed.     

Catalytic Combustion‐Type Hydrogen Sensor Using BaTiO3‐based PTC Thermistor

A catalytic combustion‐type gas sensor using a positive temperature coefficient (PTC) thermistor, which shows a sharp resistance change around Curie temperature, was developed for the detection of hydrogen. La‐doped BaTiO₃ (Ba_0.998 La_0.002 TiO₃) was prepared through a solid‐state method and an oxalic acid method. La‐doped BaTiO₃ obtained by the oxalic acid method showed improved PTC properties, due to the formation of fine particles, as compared to that prepared with the solid‐state method. The resulting sensor device showed a fairly high H₂ sensitivity in the range of 100–1000 ppm. In addition, the H₂ sensitivity and response speed were improved by coating a Pt/SiO₂ catalyst on the sensor device because the catalytic combustion efficiency of H₂ was improved by the catalyst coating.     

Implantable cardioverter defibrillator in maintenance hemodialysis patients with ventricular tachyarrhythmias: A single-center experience

Patients with hemodialysis (HD) are at risk of death due to cardiac arrhythmias, worsening congestive heart failure (CHF), and noncardiac causes. This study reviews our experience with the use of implantable cardioverter defibrillators (ICDs) in patients with ventricular tachycardia who are under maintenance HD. We retrospectively reviewed 71 consecutive patients who underwent an ICD implantation in our hospital. There were 11 patients under maintenance HD and 60 patients without HD. The group of patients with HD (HD group) was compared with the patients without HD (control group). The mean follow-up period was 30±9 vs. 39±4 months in the HD group vs. the control group, respectively. Among these patients, 6 in the HD group and 26 in the control group received appropriate ICD therapies. There was no difference in appropriate ICD therapy, time to the first therapy, and electrical storm between the 2 groups. In the HD group, 1 patient underwent surgical removal of the ICD system due to infective endocarditis. There were 5 deaths in the HD group (4 from CHF) and 8 deaths in the control group (4 from CHF). There were no sudden cardiac deaths or arrhythmic deaths in both groups of patients during the follow-up period. However, the overall death rate was significantly higher in the HD group (P<0.01). In HD patients, ICD therapy prevented arrhythmic death, but their rate of nonarrhythmic adverse outcomes was high. This risk-benefit association should be considered before implantation of the device.     

Preparation of titania-coated alumina film by electrolysis of TiCl4-containing solution

Direct current in the range from 50 to 390 mA/cm² was flowed between alumina/tin-doped indium oxide (indium tin oxide, ITO) composite (cathode) and carbon (anode) electrodes in an aqueous solution containing TiCl₄ and (NH₄)₂SO₄ at pH 0.5. The composite electrode dissolved in the solution and was precipitated again on the surface of the electrode. The thickness of precipitated layer increased at a higher applied charge. During the electrolysis, TiO₂ was also deposited on the surface of precipitated layer. The amorphous TiO₂ heated at 300 °C and sintered Al₂O₃–ITO composite showed a good adsorption property of electromagnetic energy in the wide wavelength of 200–800 nm.     

Electrochemical and magnetic studies of Cr- or Co-substituted Li-Mn-Ni spinel oxides

LiMn_1.5−xM_2xNi_0.5−xO₄ (M = Co or Cr, 0.0 ≤ x ≤ 0.2) compounds were synthesized by the sol-gel method. It is found from X-ray diffraction analysis that single spinel phases are obtained for both Cr³⁺- and Co³⁺-substitution, but a small cation mixing between the 8a and 16d sites is found only in the Co³⁺-substitution case. All of the compounds exhibit M-T curves characteristic of ferromagnetic materials. As the substitution degree is raised, the saturation magnetization at 4.2 K decreases and the Curie temperature shifts lower, irrespective of the kind of the substituent. That is, the cation substitution yields a reduction of the ferromagnetism. Additionally, both Cr³⁺- and Co³⁺-substitution have a large influence on the electrochemical properties. The Cr³⁺-substitution induces a rise in the average operating potential without a loss of redox capacity, while both the average operating potential and the redox capacity decrease with an increase in the Co³⁺-substitution degree.     

Evaluation of Design Method for Engine Output Power and Battery Energy Capacity for Lithium‐Ion Battery Hybrid Diesel Railway Vehicles

Diesel engine lithium‐ion battery hybrid vehicles are attracting attention because the energy consumption during their operation and exhaust emissions can be reduced considerably. However, a reasonably accurate method of designing the engine power and battery energy has not yet been proposed, although the above‐mentioned type of traction system can help in realizing an environment‐friendly railway vehicle. In this paper, a design method for the battery energy capacity and engine output power is proposed in the case of a control strategy in which the sum of the kinetic energy of the vehicle and the battery energy is maintained constant. The proposed method is verified by the velocity/state of charge of the battery charts obtained in experimental tests. The proposed design method can be used to develop environment‐friendly railway traction systems for nonelectrified sections.     

Epitaxial growth of GaN layers on metallic TiN buffer layers

To improve GaN light-emitting diode light emission, we produced metal organic chemical vapor deposition (MOCVD)-grown, continuous, flat GaN layers on metallic TiN buffer layers deposited on sapphire substrates. Three important conditions were found: (a) the sapphire substrate surface plane should be (1120), (b) the TiN layer surface plane should be (111), and (c) the TiN buffer layer nitrogen content should be higher than that of stoichiometric TiN. Reduction of TiN layer thickness reduced TiN buffer layer surface roughness. Threading dislocation density in GaN layers grown on TiN buffer layers was much lower than that in GaN layers grown on AlN.