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.     

Electromigration-Induced Plastic Deformation in Cu Interconnects: Effects on Current Density Exponent, <Emphasis Type="Italic">n</Emphasis>, and Implications for EM Reliability Assessment

While Black’s equation for electromigration (EM) in interconnects with n = 1 is rigorously based on the principles of electrotransport, n > 1 is more commonly observed empirically. This deviation is usually attributed to Joule heating. An alternative explanation is suggested by the recent discovery of EM plasticity. To examine this possibility, we have retested samples that had been previously subjected to a predamaging phase of high temperature and current densities to determine whether the loss of median time to failure (MTF) is retained. We find that the predamaged samples exhibit MTFs that are permanently reduced, which is a characteristic of EM plasticity.     

Hypocholesterolemic Action of Fermented Brown Rice Supplement in Cholesterol-Fed Rats: Cholesterol-lowering Action of Fermented Brown Rice

Fermented rice products have been implicated in vascular injury and atherosclerosis in recent animal and human studies. In the current study, whether consumption of differently processed brown rice diets may change the cholesterol metabolism was evaluated in male Spraque Dawley (SD) rats after 28 d of treatment with diets containing 1% cholesterol. The experimental diets include corn starch alone as control diet (CO) or a diet containing a 50% substitute of CO; uncooked brown rice (UB), cooked brown rice (CB), lactic acid bacteria (LAB), brown rice mixed with LAB (BLAB), and fermented‐brown rice by LAB (FB), respectively. Among them, FB group elicited significantly lower levels of plasma and hepatic triglycerides, plasma total cholesterol, low‐density lipoprotein cholesterol (LDL‐C), and very low‐density lipoprotein cholesterol (VLDL‐C) by 33% to 50%, whereas higher levels of HDL‐C were elicited by 227% compared with the CO group (P < 0.05). These amelioration action on lipid profile in FB group appeared to correspondent to the higher excretions of fecal weight, triglyceride (TG), total cholesterol (TC), and bile acid (P < 0.05). Furthermore, sensory properties such as flavor liking, taste liking, and overall acceptability of the diet were significantly improved by the addition of fermented brown rice. Conclusively, fermented‐brown rice may have a potent cholesterol‐lowering benefits with sensory quality improvement of the diet.     

Effect of the dehydrogenation speed and Nd content on the microstructure and magnetic properties of HDDR processed Nd-Fe-B magnets

The effect of Nd content and dehydrogenation speed on the microstructure and magnetic properties of hydrogenation-disproportionation-desorption-recombination (HDDR) processed Nd-Fe-B magnetic powders was studied. The Nd_xB_6.4Ga_0.3Nb_0.2Fe_bal (x=12.5–13.5, at.%) mold casting alloys were subjected to HDDR process after homogenization heat treatment. During desorption-recombination stage, dehydrogenation speed and time were systematically changed to control the speed of the desorption-recombination reaction. The higher Nd content resulted in better magnetic properties of the HDDR powder, and this was attributed to the thicker and more uniform Nd-rich phase at grain boundaries. It was also confirmed that the slow dehydrogenation speed could maximize the effect of high Nd content on the magnetic properties of HDDR powder. At the optimized dehydrogenation speed, the coercivity and remanence was 15.3 kOe and 13.0 kG, respectively, at 12.9 at.% Nd content, which resulted in a (BH)_max of 36.8 MGOe.     

Stress-dependent hardening-to-softening transition of hydrogen effects in nanoindentation of a linepipe steel

We explored the influences of hydrogen on small-scale strength of a linepipe steel through nanoindentation experiments with four pyramidal indenters. Interestingly, a transition from hydrogen-induced hardening to softening was observed as indenter sharpness increases. The transition was analyzed based on the enhancement in hydrogen's elastic shielding effects for a sharper indenter, which could be indirectly evidenced by the stress effects on indentation pile-up, dislocation density, and rate dependency of hardness.     

Long-term performance of anode-supported SOFC integrated with metal interconnect by joining process

Using relatively simple and cheap joining process, anode-supported solid oxide fuel cell integrated with metal interconnect is fabricated and its impedance spectra are analyzed and compared with anode-supported cell at the operating temperature of 800 °C. The stable long-term performance is shown for about 800 h at 800 °C under the constant current density of 300 mA cm⁻². The thermal cycle experiments from the operating temperature to the room temperature are also carried out in this study, while the maximum power density of 0.7 W cm⁻² is indicated. The microstructures are analyzed using scanning electron microscope and energy dispersive X-ray spectra are analyzed for observing a diffusion of metal ions at the anode, adhesion layer and metal support.     

A synthesis of CO-tolerant Nb2O5-promoted Pt/C catalyst for direct methanol fuel cell; its physical and electrochemical characterization

A Pt-Nb₂O₅/C electrocatalyst was synthesized by a two-step process as an anode material in direct methanol fuel cell (DMFC). The Pt-Nb₂O₅/C catalysts heat-treated at different temperatures (400 and 500 °C) in flowing N₂ were characterized by various methods such as inductively coupled plasma-atomic emission spectroscopy, X-ray diffraction, transmission electron microscopy, and X-ray photoemission spectroscopy (XPS). The heat-treated Pt-Nb₂O₅/C catalyst at 400 °C showed the best electrochemical activity for CO and methanol oxidations among the prepared catalysts. The XPS results showed the electronic structure change of Pt, indicating a formation of interaction between Pt and Nb₂O₅. It is suggested that a synergistic effect between Pt and Nb₂O₅ enhances the electrocatalytic activity for CO and methanol oxidations. We believe that Nb₂O₅-promoted Pt/C catalyst may be regarded as one of the attractive candidates as an anode material in DMFC.     

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.