Phase-contrast hard X-ray microscopy using synchrotron radiation for the diagnosis of onychomycosis

Onychomycosis, or fungal infection of the nail, is a disease seen frequently in clinical settings. However, the rates of positive identification using potassium hydroxide preparations or fungal cultures are relatively low. Precise diagnosis is possible via histopathologic examination to monitor the existence of fungus and performance of a fungal culture for confirmation. Phase-contrast hard X-ray microscopy using synchrotron radiation provides 70-nm spatial resolution and enables imaging of minute internal cellular structures. This study confirms the feasibility of diagnosing onychomycosis using a phase-contrast hard X-ray microscope developed at 1B2 beam line using a Pohang light source.     

Synthesis,electrochemical, and spectroelectrochemical properties of conductive poly-[2,5-di-(2-thienyl)-1H-pyrrole-1-(p-benzoic acid)]

Poly(ter-heteroaromatic(thiophene-pyrrole-thiophene)), PDPB, was electrochemically prepared from the 2,5-di(2-thienyl)-1H-pyrrole-1-(p-benzoic acid) (DPB) monomer using the Paal-Knorr pyrrole condensation reaction. The structure of the monomer was confirmed using ¹H-, ¹³C NMR, FT-IR and mass spectroscopy. The maximum UV–visible absorption and PL emission bands of DPB were observed at 330 nm and 500 nm, respectively. The cyclic voltammograms (CVs) recorded for the electrochemically polymerized DPB revealed a set of redox peaks at 0.65/0.53 V. The conductivity monotonically increased with respect to the applied potential from 0.0 V to 1.0 V, exhibiting a maximum conductivity of 0.18 S/cm at +0.80 V. The in situ UV–visible spectroelectrochemical analysis of PDPB revealed electronic transitions at 420 nm, 654 nm, and 870 nm corresponding to the π–π* transition, polaron, and bipolaron states, respectively. The optical band-gap (E_g) of PDPB was 2.16 eV. The color of the PDPB film transitioned yellow (at 0.0 V) to blue (at 1.0 V) when the potential was switched between the reduced and oxidized states with a good electrochromic response time (0.95 s).     

Catalytic decomposition of nitrous oxide over Fe-BEA zeolites: Essential components of iron active sites

The catalytic decomposition of N₂O was investigated over Fe-BEA zeolites treated with various methods such as reduction, steaming and dissolution with potassium nitrate and nitric acid solutions in order to deduce the essential components of the active sites for the decomposition. The iron species were characterized by XPS, XANES, ESR, NO adsorption, and linear sweep voltammetry. The reduction-treated Fe-BEA zeolite with the large amounts of Fe(II) and Fe(III) species showed the highest activity. On the contrary, the dissolution treatment with the potassium nitrate solution seriously deteriorated the catalytic activity of the Fe-BEA zeolite by agglomerating iron oxide clusters and interaction between iron and potassium atoms. The catalytic roles of Fe(II)/Fe(III) species and the negative effect of potassium on the catalytic activity of the Fe-BEA zeolites were discussed.     

Biosorption of heavy metals and uranium by starfish and Pseudomonas putida

Biosorption of heavy metals and uranium from contaminated wastewaters may represent an innovative purification process. This study investigates the removal ability of unit mass of Pseudomonas putida and starfish for lead, cadmium, and uranium by quantifying the adsorption capacity. The adsorption of heavy metals and uranium by the samples was influenced by pH, and increased with increasing Pb, Cd, and U concentrations. Dead cells adsorbed the largest quantity of all heavy metals than live cells and starfish. The adsorption capacity followed the order: U(VI)>Pb>Cd. The results also suggest that bacterial membrane cells can be used successfully in the treatment of high strength metal-contaminated wastewaters.     

Mechanical response of pig skin under dynamic tensile loading

Uniaxial tensile experiments were performed on pig skin to investigate the tensile stress–strain response at both quasi-static and dynamic rates of deformation. A Kolsky tension bar, also called a split Hopkinson tension bar (SHTB), was modified to conduct the dynamic experiments. Semiconductor strain gages were used to measure the low levels of the transmitted signal from pig skin. A pulse shaper technique was used for generating a suitable incident pulse to ensure stress equilibrium and approximate constant strain rate in the specimen of a thin skin sheet wrapped around the ends of the bars for minimizing radial inertia. In order to investigate the strain-rate effect over a wide range of strain rates, quasi-static tests were also performed. The experimental results show that pig skin exhibits rate-sensitive, orthotropic, and non-linear behavior. The response along the spine direction is stiffer at lower rate but is less rate sensitive than the perpendicular direction. An Ogden model with two material constants is adopted to describe the rate-sensitive tensile behavior of the pig skin.     

AM radio circuit using printed electronic components

In this paper, printing technologies have been employed to print the resonant circuit and detection circuit for an amplitude modulation system (AM radio), which consists of a printed inductor, capacitor, resistor and diode on plastic foils for using as an AM radio circuit. To test the printed inductor, capacitor, resistor and diode as components of AM radio, we selected 640 KHz, the strongest AM frequency in Sunchon City, Korea and monitored the audio signal by replacing each component by a corresponding printed one. As a result the 640 KHz AM radio signals were detected.     

Multivariate crash modeling for motor vehicle and non-motorized modes at the macroscopic level

Macroscopic traffic crash analyses have been conducted to incorporate traffic safety into long-term transportation planning. This study aims at developing a multivariate Poisson lognormal conditional autoregressive model at the macroscopic level for crashes by different transportation modes such as motor vehicle, bicycle, and pedestrian crashes. Many previous studies have shown the presence of common unobserved factors across different crash types. Thus, it was expected that adopting multivariate model structure would show a better modeling performance since it can capture shared unobserved features across various types. The multivariate model and univariate model were estimated based on traffic analysis zones (TAZs) and compared. It was found that the multivariate model significantly outperforms the univariate model. It is expected that the findings from this study can contribute to more reliable traffic crash modeling, especially when focusing on different modes. Also, variables that are found significant for each mode can be used to guide traffic safety policy decision makers to allocate resources more efficiently for the zones with higher risk of a particular transportation mode.     

Heavy metals in spices commonly consumed in Republic of Korea

Levels of lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) were evaluated in 359 samples of commonly consumed spices (cinnamon, parsley, basil, oregano, coriander seed, nutmeg, cumin, bay leaf, fenugreek, rosemary, thyme, fennel, sage, clove, marjoram, tarragon, caraway, dill seed, pepper, and turmeric) from the market in the Republic of Korea. The content of Pb, Cd, and As was assessed by acid wet digestion using a microwave oven and inductively coupled plasma mass spectrometry (ICP-MS). The content of Hg was analysed using a direct mercury analyzer (DMA). Pb, Cd, As, and Hg mean content in spices ranged from 0.039–0.972 mg kg^?1, 0.013–0.315 mg kg^?1, 0.121–0.861 mg kg^?1, and 0.001–0.025 mg kg^?1, respectively.     

Analytical formulation of mode-coupling instability in disc-pad coupled system

This paper describes the mode-coupling-type squeal mechanism in a disc brake system. The mode shapes of a disc and a brake pad (an annular sector plate) are obtained using the component eigenvalue analysis and the Rayleigh-Ritz method, respectively. The disc-pad coupled system subject to friction-couple is discretized by the truncated set of system component modes. Mode-coupling instability is determined in closed form resulting from a reduced-order friction-coupling model, which subsequently defines the modal stability index. The proposed index parameter determines the necessary condition for flutter instability without solving system complex eigenvalues. The numerical investigation shows that the disc-pad modal interaction has a strong squeal tendency when two pads are not identical.