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This paper reports an increase in the optical reflectivity of two kinds of copolymers used in contact lenses, with different proportions of silicon and fluorine derivatives, when irradiated with 4.1 MeV alpha particles from an 241Am source. The fiber-optic reflectance technique showed that the lens with a higher proportion of silicon and fluorine content and a lower proportion of methyl-methacrylate is more susceptible to alpha radiation. X-Ray photoelectron spectroscopy and Raman spectroscopy have revealed the formation of silicon oxide and carbide species as a result of chain scission and recombination in the 20 μm thick irradiated regions of lens materials. It is presumed that the high (260 eV/nm) linear energy transfer of alpha particles in polymers creates trapped gas “Bubbles”, and the observed increase in the optical reflectivity with increased irradiation time is explained on the basis of diffuse reflectance caused by the scattering of light from the hard surfaces of these “Bubbles”.

The lower Albian Jinju Formation has produced various fossils of invertebrates. Of them, insect fossils have remained understudied, and especially, orthopteran fossils have never been described from the Jinju Formation. Here we report a new species of the Elcanidae (Orthoptera: Elcanoidea), Panorpidium spica sp. nov. based on three specimens from the Jinju Formation. Notably, we have applied Wavelength Dispersive Spectrometer (WDS) analysis for the first time on insect fossils, and discovered that the carbon elemental maps are helpful in recognizing crucial morphology. The presence of pterostigmata in forewing supports that elcanids evolved a unique flight mechanism distinct from other extant orthopterans. Based on a detailed morphological comparison with the paddles of the extant tridactylids, it is inferred that the leaf-shaped spurs on the metatibiae of elcanids were used for jumping on the water, although other possible functions cannot be ruled out. Diving into the water and jumping on the water surface must have been an effective way of escaping from predators, both for the flightless nymphs and the short-range flying adults.

To evaluate the level of fine particulate matters in elementary schools located in a high traffic area of Seoul and verify the emission source, a field study on the classrooms was conducted under the uncontrolled condition. The indoor PM2.5 was lower than that of the outdoors as indicated by an I/O ratio of 0.52-0.92 based on mass concentration, and it was maintained below the National Guideline. Heavy metals such as Cr, Mn, Ni, Cu, Zn, As, Sn and Pb were lower in indoor PM2.5 than outdoors. On the contrary, carbons including OC and EC were higher in indoor PM2.5. As a result of source apportionment analysis, an outdoor emission source was responsible for 58.5% of the classroom PM2.5. This study can contribute to urban planning and school design to keep children safe from harmful environments.

Hyaluronate has attracted great attention in tissue engineering as a scaffolding material. However, hyaluronate typically requires chemical cross-linking molecules to form hydrogels, which may induce undesirable side effects in the body. In this study, hyaluronate was partially oxidized with sodium periodate to generate aldehyde groups in the backbone, and simply mixed with glycol chitosan to form gels via Schiff base formation. The effects of the degree of oxidization, polymer concentration, and polymer composition on the mechanical properties of oxidized hyaluronate/glycol chitosan hydrogels were investigated in vitro. Degradation behavior and biocompatibility of oxidized hyaluronate/glycol chitosan gels were also evaluated in vitro. This system may be potentially useful as an injectable system in many tissue engineering applications, including cartilage regeneration.

Neutrons over a wide range of energies are produced by bombarding a 1.05 cm thick beryllium target with protons of different energies delivered by the MC-50 Cyclotron of the Korea Institute of Radiological Medical Sciences (KIRAMS). The neutron flux Φ(En) versus neutron energy En, produced by protons of 30, 35, and 40 MeV energies, was obtained by using the GEANT4 code with a data-based hadronic model. For the experimental validation of the simulated neutron spectra, a number of pure aluminum and iron oxide samples were irradiated with the neutrons produced by 30, 35, and 40 MeV protons at 20 μ A beam current. The gamma-ray activities of 24Na and 56Mn produced, respectively, through 27Al(n,α)24Na and 56Fe(n,p)56Mn reactions were measured by a HPGe detector. The neutron flux Φ(En) at each neutron energy from the simulation was multiplied with the evaluated cross-sections σ(En) of the respective nuclear reaction, and the summation ∑ Φ ( E n ) σ ( E n ) was calculated over the neutron spectrum for each proton energy of 30, 35, and 40 MeV. The measured gamma-ray activities of 24Na and 56Mn were found in good agreement with the activities estimated by using the summed values of ∑ Φ ( E n ) σ ( E n ) along with other parameters in a neutron activation method.

The latent tracks formed on CR-39 solid state track detector on exposure of alpha radiations emanating from a collimated 241 Am source were developed by a chemical etching method. Alpha track images were captured by an optical microscope and were processed by using Image Pro-Plus (6.0) software. GEANT4 simulations were carried out to obtain the angular and energy distribution profiles of the alpha particles. Apart from fluence, geometric parameters like aspect ratio (the ratio of the major to minor axis) and the depth profiles of etched tracks were measured experimentally and correlated with simulated angular and energy profile of incident radiations. Reasonable agreement was observed in the fluence and depth profile information obtained from experiments and simulations.

Recently, we reported n-type graphene can be achieved simply using H2 molecules. It was understood by the attachment of hydrogen atoms dissociated on the surface of graphene. However, the amount of attached hydrogen has not been yet investigated. Here, we show the possibility of the formation of C H bonds due to the H2 exposure theoretically and the mass of the attached hydrogen atoms on graphene experimentally. The amount of the attached hydrogen atoms has been measured by a quartz crystal microbalance (QCM). After exposure of a multilayer graphene (MLG) to 20 bar of H2 pressure at 353 K for 20 h, the resonance frequency (RF) of QCM decreased. It indicates that the mass of the MLG increases. On the basis of the RF variation, we concluded that the hydrogen atoms were bonded to 3.84% of carbon atoms in the MLG. In order to confirm the C H bonding of MLG, Raman spectroscopy was performed before and after exposure to H2 pressure. On exposure, the D peak developed and the peak for 2-D graphite in 2D band increased. The experimental results and theoretical calculation demonstrate that the H2 molecules on the surface of the graphene are dissociated and that some of dissociated H atoms are attached on graphene.

MICROMEGAS detectors have been developed for the detection and tracking of charged and neutral particles. The control parameters of MICROMEGAS include materials, the type of gases, the mixing ratio of gases and the geometry. Simulations of MICROMEGAS are conducted to optimize the characteristics and performance with respect to the nature of the gas mixture, applied voltages of drift and amplification regions. Quantities such as the equi-potential lines, electron drift lines, and avalanche process of electrons and ions are calculated. Two MICROMEGAS detectors are built and characterized by using standard X-ray sources. The voltage gains are measured against the applied voltage range for different gas pressures and are compared with our simulation results.

Background The role of neoadjuvant chemotherapy for resectable colorectal liver metastases is a subject of debate. We compared the oncologic outcomes between neoadjuvant chemotherapy and adjuvant chemotherapy combined with surgery for resectable synchronous colorectal liver metastases. Methods We analyzed 30 patients who underwent liver resection for resectable colorectal liver metastases combined with oxaliplatin-based neoadjuvant or adjuvant chemotherapy between May 2003 and August 2010. We assessed recurrence-free and overall survival in patients treated using neoadjuvant chemotherapy compared with those who received adjuvant chemotherapy. Results Of the 30 patients with colorectal liver metastases, 15 underwent neoadjuvant chemotherapy and 15 underwent adjuvant chemotherapy. Nine (60%) patients in the adjuvant group relapsed and nine (60%) patients in the neoadjuvant group relapsed. The neoadjuvant chemotherapy group had no significant difference in recurrence-free and overall 3-y survival (37.5% versus 45.0%, P = 0.938; 44.0% versus 66.7 %, P = 0.466) compared with the adjuvant chemotherapy group. Conclusion Our results indicate that neoadjuvant chemotherapy is not inferior to adjuvant chemotherapy for resectable colorectal liver metastases, although the study was not randomized and included a limited number of patients.

The authors report on the optical properties of multi-dimensional ZnO hybrid structures, consisting of film (2D)/nanorods (1D)/sapphire substrate (2D), grown by metalorganic chemical vapor deposition (MOCVD). Photoluminescence investigations reveal that the sample with top layer grown at a decreased growth temperature of 240 °C and increased reactor pressure of 5 Torr exhibits superior emission properties. The presence of strong E2high optical phonon mode at 438.5 cm− 1 in the visible micro-Raman spectra demonstrates the wurtzite nature of ZnO. Although the ultraviolet Raman scattering measurements of the hybrid structures reveal the presence of in-plane tensile stress in the top ZnO layer, the sample with the improved emission performance shows the release of tensile stress.

The photolithography process has generally been used for the making of catalyst layers used for the synthesis of CNTs due to its comparative ease. However, this method results in the formation of undesirable catalyst particles, which deteriorate the quality of the devices. Therefore, we tried to form a catalyst layer without using any lift-off or wet etching process, especially for the formation of carbon nanotube interconnects. After spin coating the samples, which were previously fabricated with several vias, with an iron-acetate solution, the catalyst layer was pulled down into the bottom of the holes through the force of gravity. We were able to remove the catalyst layer which was coated over undesirable areas, by TMAH (tetramethylammonium hydroxide, N(CH3)4OH) treatment. After the catalyst deposition process, we synthesized CNTs and observed them by scanning electron microscopy (SEM). © 2007 Published by Elsevier B.V.

Nodakenin is a coumarin compound initially isolated from the roots of Angelica gigas. In the present study, we investigated the effects of nodakenin on learning and memory impairments induced by scopolamine (1 mg/kg, i.p.) using the passive avoidance test, the Y-maze test, and the Morris water maze test in mice. Nodakenin (10 mg/kg, p.o.) administration significantly reversed scopolamine-induced cognitive impairments in the passive avoidance test and the Y-maze test (P

The one-dimensional ZnO nanostructures prepared through thermal evaporation under various cooling down procedures by changing the flow rates of the carrier gas and the reactive gas were investigated. The nanorod structures were changed into the nanonail types with a broad head through the reduction of the flow rate of the carrier gas. The decrease of the reactive gas reduced the length of the nail heads due to the limited mass transport of reactive gas. The intensity ratio of the ultraviolet emission/green emission of photoluminescence was proportional to the length of the broad head showing a larger surface area. The vertically aligned nanostructures were grown along the [0 0 0 1] direction of ZnO regardless of the aligned directions. The crystal direction of the nanostructures was determined by that of the initial ZnO crystal.

The density-controlled carbon nanotubes (CNTs) were grown on the iron nanoparticles by using the freeze–dry method. The iron-acetate [Fe(II)(CH3COO)2] solution was used for the preparation of the catalytic iron nanoparticles. The density of CNTs was controlled in order to achieve the enhancement in the field emission process. Furthermore, the patterning of the iron nanoparticle catalyst layer for the fabrication of electronic devices was simply achieved by using an alkaline solution, TMAH (tetramethylammonium hydroxide). We applied this patterning process of catalyst layer to the formation of the electron emitter with under-gate type triode structure.

We studied the growth characteristics of carbon nanotubes which were grown from the uniformly dispersed iron nanoparticles prepared from iron acetate [Fe(II)(CH3COO)2]. The density of CNT was controlled from precursor concentrations. We also investigated the field emission properties of CNTs. We found that the optimization of CNT density is an important factor for field emission properties. Patterning process of iron acetate was achieved simply by alkaline solution.

For field emitters as a cathode of traveling wave tube–microwave power amplifiers (TWT–MPA), field-emission (FE) properties of in situ grown carbon nanotubes (CNTs) onto electrically conducting substrate were systematically characterized. CNTs grown on the Co/TiN coated Ta substrate with properly controlled process exhibited the best FE property. The maximum current density and corresponding total emission current were 3.5 mA/cm 2 and ∼1.7 mA at 21.6 V/μm, respectively. Details on the correlation between the FE properties and the morphological parameters will be discussed.

This paper deals with a matching problem of finding correspondences of features in two omnidirectional images. To produce reliable matching results even though there are large translation and rotation of a sensor, we proposed a method that combines the advantages of sum of squared difference (SSD) and dynamic time warping (DTW). Dominant corresponding feature pairs are found using a proximity matrix and an SSD-based similarity matrix, and then the remaining feature matching is accomplished by DTW. Experimental results show that a zero failure rate of matching can be achieved in an indoor environment if the baseline is less than 20 cm.

We have investigated the notion of machine intelligence, based on extensive literature survey and have proposed two methods to measure intelligence of a machine. Specially, we have first analyzed those engineering systems or products that are said to be intelligent and have extracted four common constructs, each of which consists of several variables. Based on them, we have then suggested two typical models, which are represented as entities in three-dimensional construct space. In order to find a number, called machine intelligence quotient (MIQ), we adopt two fuzzy integrals, Sugeno fuzzy integral and Choquet fuzzy integral. Two application examples are given for the typical models using two fuzzy integrals, and comparative comments are made.