A simple background elimination method for Raman spectra

In this paper, we consider a new background elimination method for Raman spectra. The proposed method is based on peak detection, smoothing, and interpolation. Since the background is usually slowly varying with respect to wavelength, we could estimate the background by eliminating significant peaks. For this purpose, we seek the peaks by inspecting the smoothed derivative of a given spectrum. After clipping out the corresponding peak regions, we estimate the background by applying a modified linear interpolation. Then the background is eliminated from the measured Raman spectrum by simple subtraction. The experimental results showed that the proposed method gave satisfactory results for real Raman spectra as well as synthetic data. As the proposed method requires no prior knowledge of spectrum, we expect that the method could be applied to other spectral data as well.     

Preparation of Pt/NiO-C electrocatalyst and heat-treatment effect on its electrocatalytic performance for methanol oxidation

Pt catalyst supported on Vulcan XC-72R containing 5 wt% NiO (Pt/NiO–C) showed larger electrochemical active surface area and higher electrochemical activity for methanol oxidation than Pt catalyst supported on Vulcan XC-72R using polyol method without NiO addition. Prepared Pt/NiO–C electrocatalyst was heat-treated at four temperatures (200, 400, 600, and 800 °C) in flowing N₂. X-ray diffraction and temperature-programmed desorption results indicated that NiO was reduced to Ni in inert N₂ during heat-treatments at temperatures above or equal to 400 °C, while oxygen from NiO reacted with carbon support due to the catalytic effect of Pt. The reduced Ni formed an alloy with Pt, which, according to the X-ray photoelectron spectroscopy data, resulted in a shift to a lower binding energy of Pt 4f electrons. The Pt/NiO–C electrocatalyst heat-treated at 400 °C showed the best activity in methanol oxidation due to the change in Pt electronic structure by Ni and the minimal aggregation of Pt particles.     

Loosening mechanism of threaded fastener for complex structures

Journal of Mechanical Science and Technology - Threaded fasteners are widely used in mechanical structures primarily owing to their easy disassembly for maintenance and low cost. However, the...     

Improved workability using preheating in the electromagnetic forming process

Journal of Mechanical Science and Technology - Electromagnetic forming (EMF) is a high-speed method used to shape metals using a high-energy magnetic field generated by a forming coil. In this...     

Major findings from LBLOCA reflood tests using the ATLAS facility

A set of LBLOCA (large-break loss of coolant accident) reflood tests was performed in the first phase of the ATLAS (advanced thermal-hydraulic test loop for accident simulation) program. Their main objectives were to identify the major thermal-hydraulic characteristics during the reflood phase of a LBLOCA for APR1400 and to provide qualified data for APR1400 licensing. The ATLAS reflood test program could be divided into two phases (Phase-1 and Phase-2) according to the target period to be simulated. The Phase-1 tests were parametric effect tests for downcomer boiling in the late reflood phase of LBLOCA and the Phase-2 tests were integral effect tests for the entire reflood phase of LBLOCA. The experimental results from both Phase-1 and Phase-2 tests reproduced typical thermal-hydraulic trends expected to occur during the APR1400 LBLOCA scenario. A separate effect test was also performed under a low reflooding rate condition to provide data to validate the RELAP5 reflood models, and its experimental results showed a gradual reflooding in the core, a subsequent quenching of the core heater rods and the cooling of the reactor pressure vessel downcomer.     

Optical property of silicon quantum dots embedded in silicon nitride by thermal annealing

We present the effects on the thermal annealing of silicon quantum dots (Si QDs) embedded in silicon nitride. The improved photoluminescence (PL) intensities and the red-shifted PL spectra were obtained with annealing treatment in the range of 700 to 1000 °C. The shifts of PL spectra were attributed to the increase in the size of Si QDs. The improvement of the PL intensities was also attributed to the reduction of point defects at Si QD/silicon nitride interface and in the silicon nitride due to hydrogen passivation effects.     

Annealing behavior of TiO<Subscript>2</Subscript>-sheathed Ga<Subscript>2</Subscript>O<Subscript>3</Subscript> nanowires

TiO₂-sheathed Ga₂O₃ one-dimensional (1D) nanostructures were synthesized by thermal evaporation of GaN powders and then sputter-deposition of TiO₂. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis results indicate that the Ga₂O₃ cores are of a single crystal nature with a monoclinic structure while the TiO₂ shells are amorphous. Photoluminescence (PL) emission is slightly decreased in intensity by TiO₂ coating, but it is significantly increased by thermal annealing in an oxygen atmosphere. The emission peak is also shifted from ~500 to ~550 nm by oxygen annealing. The increase in the green emission is due to the increase in the concentration of the Ga vacancies in the cores by the inflow of oxygen during oxygen annealing. On the other hand, annealing in a nitrogen atmosphere leads to a red shift of the emission to ~700 nm originating from nitrogen doping.     

Warpage of a large‐sized orthogonal stiffened plate produced by injection molding and injection compression molding

Rectangular plates of the size of 1800 × 600 × 12 mm³ and 1200 × 600 × 12 mm³ were selected for injection molding and injection compression molding, respectively, in order to investigate warpage characteristics of the large‐sized polymer plates with orthogonal stiffener. To determine the mold system and to reduce warpage of the specimen, numerical analyses for injection molding and injection compression molding were performed by using a commercial simulation code. Experiments were performed to verify the suggested mold system and warpage of the specimen. Relatively large warpage of the injection molded product was observed and small warpage of the injection compression molded product was generated. Compression force of the injection compression molding was only 6% of the clamp force of the injection molding. Warpage of the product was reduced significantly by using the injection compression molding. The injection compression molding will be used to substitute expensive and disused wood forms with inexpensive and recyclable polymer plates for concrete casting. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Enhancement of the Li ion transfer reaction at the LiCoO2 interface by 1,3,5-trifluorobenzene

This work presents a method of enhancing the kinetics of the interfacial reaction using 1,3,5-trifluorobenzene (TFB) which is used as an electron acceptor due to its locally biased polarity and as a source of rearranging the layer of the electrolyte around LiCoO₂ electrode, not a SEI layer source. The full cells with TFB show a decrease in irreversible capacity loss during the first charge-to-discharge process, regardless of the SEI layer formation, and also show better discharge properties even at high rate conditions. The charge transfer resistance (R_ct) of the LiCoO₂ half cell with TFB shows the smaller resistance than that of the TFB free half cell, and the activation energy calculated from the R_ct was 24.7 kJ/mol for the TFB free half cell and 19.3 kJ/mol for the half cell with TFB. In addition, the film resistance of the half cell with TFB shows higher value when the temperature is below 283 K. Since R_ct is related to the transfer resistance of the solvated Li⁺ ions on the surface of the LiCoO₂ electrode, it will help design the electrolyte to improve the transfer velocity of Li⁺ ions around the cathode electrode for high power Li ion battery.     

Glycoproteins isolated from Atractylodes macrocephala Koidz improve protective immune response induction in a mouse model

Food Science and Biotechnology - This study examined the efficacy of Atractylodes macrocephala Koidz (AMK) protein and polysaccharide extracts as adjuvant or adjuvant booster when given together...