Viscosity dependence of electrochemical etching for gold tip fabrication

We suggest an electrochemical etching method with viscous etchant to enhance the sharpness of tip of scanning probe microscope. The viscosity of the etchant mixed with HCl solution and glycerol was used as a control parameter in addition to the voltage applied to the tip. In order to improve the sharpness of the tip, a nano-scale meniscus formed between the end of the tip and the liquid level was used. The shapes, aspect ratios, and radii of tips were measured depending on the concentration of the etchant. It was found that the tip etched with the mixed liquid with glycerol was sharper than the tip with the pure HCl solution. This can be explained by the fact that the meniscus formed by viscous liquid is maintained with a thinner diameter and causes final etching until the meniscus bridge is ruptured.     

A Mild and Efficient Tetrahydropyranylation of Alcohols

Triphenylphosphine (TPP)-iodotrimethylsilane (TMSI) was found to be a convenient and highly effective catalyst for the tetrahydropyranylation of aliphatic and aromatic alcohols with dihydropyran in dichloromethane at ambient temperature.     

Recent Developments in Robust Portfolios with a Worst-Case Approach

Robust models have a major role in portfolio optimization for resolving the sensitivity issue of the classical mean–variance model. In this paper, we survey developments of worst-case optimization while focusing on approaches for constructing robust portfolios. In addition to the robust formulations for the Markowitz model, we review work on deriving robust counterparts for value-at-risk and conditional value-at-risk problems as well as methods for combining uncertainty in factor models. Recent findings on properties of robust portfolios are introduced, and we conclude by presenting our thoughts on future research directions.     

Measurement of <Superscript>99</Superscript>Mo production cross-section from the <Superscript>100</Superscript>Mo(n,2n) reaction with quasi monoenergetic neutron based on the <Superscript>9</Superscript>Be(p,n) reaction

The production cross-section of the medical isotope, ⁹⁹Mo from the enriched ¹⁰⁰Mo(n,2n) reaction with the average neutron energies of 21.9 and 26.5 MeV has been determined for the first time by using an off-line γ-ray spectrometric technique. The average neutron energies were generated by using the ⁹Be(p,n) reaction with the proton energies of 35 and 45 MeV from the MC50 cyclotron of the Korea Institute of Radiological and Medical Sciences (KIRAMS) at Seoul, South Korea. The ¹⁰⁰Mo(n,2n) reaction cross-section as a function of neutron energy was also calculated theoretically by using the computer code TALYS-1.8 and EMPIRE-3.2 Malta. The experimental results are in close agreement with the theoretical values from TALYS-1.8. However, the present data at the neutron energy of 21.9 MeV is slightly lower and at 26.5 MeV is higher than the values from EMPIRE-3.2 Malta.     

Synthesis and visible light photocatalytic activity of Ag spot-coated TiO2–60 wt% SrO composite powders

Nano-sized TiO₂–60 wt% SrO composite powders were synthesized from titanium isopropoxide and Sr(OH)₂·8H₂O by use of a sol–gel method. Ag spot-coated TiO₂–60 wt% SrO composite powders containing 3, 5, or 7 wt% Ag were synthesized by hydrothermal-assisted attachment, by use of Ag hydrosol in a high-pressure bomb at 250 °C and 450 psi. Nano-sized Ag particles approximately 5–25 nm in diameter adhered to the TiO₂–60 wt% SrO₂ composite powders. The photocatalytic activity of Ag spot-coated TiO₂–SrO powders in the degradation of phenol showed that all were highly active when irradiated with UV light. TiO₂–60 wt% SrO composite powder spot-coated with 5 wt% Ag was more photocatalytically active under visible light than TiO₂–SrO composite powder.