Study on the Nano-structured Materials for Energy Storage System

The Li-oxygen cell is an emerging energy storage system which has a great promise in the near future for its high energy density and use of free oxygen available from the air. This energy system is attractive since it has nine times higher energy density than conventional lithium-ion cells based on LiCoO2 and graphite. However, this deceptively simple system poses many challenges which must be overcome before it could be considered for any practical application. Firstly, the formation of the insulating and insoluble reaction product, lithium peroxide, requires the highly porous, yet electronically well percolated cathode structure for the reasonable performance. Secondly, the decomposition of lithium peroxide usually involves the huge anodic overpotential which requires the development of highly efficient catalyst. Thirdly, a proper electrolyte system should be developed which is resistant to both the superoxide attack during the discharge reaction and the highly oxidizing environment during the charge process where both oxygen radicals and catalysts are present. Lastly, protection of the lithium anode is necessary, otherwise oxygen radicals in the solvent will react with lithium metal spontaneously, which eventually increases the impedance and more importantly depletes lithium metal from the anode. This thesis is primarily focused on the development of highly efficient catalysts for oxygen reduction and oxygen evolution reactions for the rechargeable Li-oxygen battery. To this end, a highly porous and electrically networked cathode film was manufactured by utilizing common plasticizers as pore forming agents and a Li-oxygen testing cells were developed using Swagelok fittings. The Li-oxygen cell test in two different electrolyte systems shows that the reactivity of electrolyte system to superoxide radicals is a key parameter to determine the nature of reaction product. For LiBOB/PC system, both LIBOB and PC are actively decomposed by superoxide radicals to produce lithium oxalate and lithium carbonate as main discharge products. In the case of LiPF6/TEGDME system, both salt and solvent are stable and thus ideal discharge product, lithium peroxide is obtained. Lead ruthenate and bismuth ruthenate with the extended pyrochlore structure show an excellent catalytic activity by increasing discharge capacity and lowering the anodic overpotential considerably during charge process in both electrolyte systems. They reduce the decomposition of electrolyte system and the extent of carbon corrosion, which accounts for more efficient cycling. The excellent catalytic activity of these pyrochlores originates from their intrinsic oxygen vacancies, electronic conductivity and many surface active sites afforded by its morphology. The performance of this catalyst was further increased through gold deposition on the pyrochlore surface, resulting in much increased discharge capacity. The pyrochlore coated carbon was proposed as a type of catalyst for an efficient way to reduce the amount of catalyst and enhance homogenous mixing with other components. The investigation on the lithium peroxide decomposition mechanism shows that carbon corrosion which occurs at around 4.0 V by lithium peroxide makes further decomposition difficult without a catalyst. In the presence of catalyst, almost full decomposition of lithium peroxide occurs with a lowered decomposition potential even though carbon corrosion still occurs. This gives a hint that the generation of a nano-porous structure and the homogenous distribution of catalyst over these pores are very important, as well as use of a highly efficient catalyst for lowering activation overpotentials. In conclusion, although there are still many obstacles present, as listed above, for the commercial application of Li-oxygen cell, these hurdles are surmountable in the near future by intensive research and the results shown in this thesis can be a cornerstone for further research. Supercapacitors based on metal oxide are new energy storage devices for ultrafast charging and discharging with decent energy density over hundreds of thousands of cycles for many commercial electronic devices and power tools. The surface redox nature of these reactions requires the creation of high surface area for better utilization and performance. Hydrous ruthenium dioxide is one of the most attractive supercapacitor materials owing to its high pseudo-capacitance and metallic character, which facilitate fast electron movement. In this thesis, a simple process involving soft liquid crystal templating using cationic surfactant and gentle heat-treatment in the mild temperature was developed to prepare mesoporous ruthenium oxide with a quasi-crystalline wall character, which has a high surface area and controlled water contents in the structure. The electrochemical testing results exhibited a promising performance of high gravimetric capacitance and a good rate capability facilitated by high surface area as well as porous structure.1 yea

Computational Prediction of Protein-Protein Interactions of Human Tyrosinase

The various studies on tyrosinase have recently gained the attention of researchers due to their potential application values and the biological functions. In this study, we predicted the 3D structure of human tyrosinase and simulated the protein-protein interactions between tyrosinase and three binding partners, four and half LIM domains 2 (FHL2), cytochrome b-245 alpha polypeptide (CYBA), and RNA-binding motif protein 9 (RBM9). Our interaction simulations showed significant binding energy scores of −595.3 kcal/mol for FHL2, −859.1 kcal/mol for CYBA, and −821.3 kcal/mol for RBM9. We also investigated the residues of each protein facing toward the predicted site of interaction with tyrosinase. Our computational predictions will be useful for elucidating the protein-protein interactions of tyrosinase and studying its binding mechanisms

Efficacy and safety of hepatic arterial infusion chemotherapy for advanced hepatocellular carcinoma as first-line therapy

Background/AimsHepatic arterial infusion chemotherapy (HAIC) with 5-fluorouracil and cisplatin for intractable advanced hepatocellular carcinoma (HCC) may have survival benefits. We aimed to determine the efficacy and safety of HAIC for advanced HCC as first-line therapy.MethodsA total of 54 patients who received only HAIC with 5-fluorouracil (750 mg/m2 on days 1-4) and cisplatin (25 mg/m2 on days 1-4) for advanced HCC from Jan. 2009 to Dec. 2011 were selected. According to Child-Pugh class, the overall survival (OS), progression-free survival (PFS), and adverse events after HAIC were investigated retrospectively.ResultsMedian OS and PFS between the Child-Pugh A group (n=24) and the Child-Pugh B/C group (n=30) were 8.7 (95% confidence interval [CI]: 4.7-12.7) vs. 3.7 months (95% CI: 2.0-5.3), and 7.1 (95% CI: 3.8-10.4) vs. 3.6 months (95% CI: 2.0-5.2), respectively. Although median OS and PFS were not statistically significant between the two groups (P=0.079, P=0.196), the Child-Pugh class B/C tended to influence poor OS. Serious adverse events ≥ grade 3 occurred frequently in both groups (83.3 vs. 96.7%, P=0.159). Responders (22.2%, complete or partial response) significantly differed in median OS, compared to non-responders (13.1 vs. 4.4 months, P=0.019). Achievement of complete or partial response was an independent prognostic factor of OS (hazard ratio: 0.4, 95% CI: 0.2-0.8, P=0.011).ConclusionsAchievement of response after HAIC provide a survival benefit in patients with advanced HCC, but HAIC should be administered cautiously in patients with Child-Pugh class B/C, because of a relatively low survival and high incidence of serious adverse events

Necrotizing fasciitis involving the chest and abdominal wall caused by Raoultella planticola

<p>Abstract</p> <p>Background</p> <p><it>Raoultella planticola </it>was originally considered to be a member of environmental <it>Klebsiella</it>. The clinical significance of <it>R. planticola </it>is still not well known.</p> <p>Case presentation</p> <p>We describe the first case of necrotizing fasciitis involving the chest and abdominal wall caused by <it>R. planticola</it>. The identity of the organism was confirmed using 16S rRNA sequencing. The patient was successfully treated with the appropriate antibiotics combined with operative drainage and debridement.</p> <p>Conclusions</p> <p><it>R. planticola </it>had been described as environmental species, but should be suspected in extensive necrotizing fasciitis after minor trauma in mild to moderate immunocompromised patients.</p

Anesthesia of a dental patient with Angelman syndrome -A case report-

Angelman syndrome is characterized by a partial deficit of paired autosomal chromosome 15, which contains a subunit of the GABA (Gamma-Amino Butyric Acid) receptor. Many drugs that act on the CNS (Central Nerve System) during anesthesia are believed to exert their effects via the GABA receptors. We describe the anesthesia of a 7 year-old female patient with Angelman syndrome who underwent surgery for dental caries. The basic factors that needed to be considered when administering anesthesia to this patient were epilepsy, significant dominance of the vagal tone, craniofacial abnormalities and peripheral muscular atrophy. Inhalational anesthetics (sevoflurane) were employed for this patient. The patient had an uneventful peri-operative period and was discharged home on the same day of the operation

Large microwave generation from d.c. driven magnetic vortex oscillators in magnetic tunnel junctions

Spin polarized current can excite the magnetization of a ferromagnet through the transfer of spin angular momentum to the local spin system. This pure spin-related transport phenomena leads to alluring possibilities for the achievement of a nanometer scale, CMOS compatible and tunable microwave generator operating at low bias for future wireless communications. Microwave emission generated by the persitent motion of magnetic vortices induced by spin transfer effect seems to be a unique manner to reach appropriate spectral linewidth. However, in metallic systems, where such vortex oscillations have been observed, the resulting microwave power is much too small. Here we present experimental evidences of spin-transfer induced core vortex precessions in MgO-based magnetic tunnel junctions with similar good spectral quality but an emitted power at least one order of magnitude stronger. More importantly, unlike to others spin transfer excitations, the thorough comparison between experimental results and models provide a clear textbook illustration of the mechanisms of vortex precessions induced by spin transfer

Compositional assessment of carotenoid-biofortified rice using substantial equivalence

One important aspect in assessing the safety of genetically modified (GM) crops for human consumption is characterizing their nutrient composition. A β-carotene-biofortified rice was generated by inserting phytoene synthase (Psy) and carotene desaturase (Crtl) genes isolated from Capsicum and Pantoea into the genome of a conventional variety of rice (Nakdongbyeo). Nutrients (proximates, amino acids, fatty acids, minerals, and vitamins), anti-nutritive components (trypsin inhibitors and phytic acid), and ferulic acid in GM rice were compared with those in the parent line Nakdongbyeo. Statistical comparisons to test for equivalence showed that all of the analyzed components in the GM plants were equivalent to those in its non-transgenic counterpart, and most nutritional components fell within the range of values reported for other commercial lines, indicating the safety of the GM plant.Key words: Genetically modified crop, β-Carotene, Transgenic rice, Nutrient, Substantial equivalence

Decreased C-reactive protein induces abnormal vascular structure in a rat model of liver dysfunction induced by bile duct ligation

Background/Aims Chronic liver disease leads to liver fibrosis, and although the liver does have a certain regenerative capacity, this disease is associated with dysfunction of the liver vessels. C-reactive protein (CRP) is produced in the liver and circulated from there for metabolism. CRP was recently shown to inhibit angiogenesis by inducing endothelial cell dysfunction. The objective of this study was to determine the effect of CRP levels on angiogenesis in a rat model of liver dysfunction induced by bile duct ligation (BDL). Methods The diameter of the hepatic vein was analyzed in rat liver tissues using hematoxylin and eosin (H&E) staining. The expression levels of angiogenic factors, albumin, and CRP were analyzed by real-time PCR and Western blotting. A tube formation assay was performed to confirm the effect of CRP on angiogenesis in human umbilical vein endothelial cells (HUVECs) treated with lithocholic acid (LCA) and siRNA-CRP. Results The diameter of the hepatic portal vein increased significantly with the progression of cirrhosis. The expression levels of angiogenic factors were increased in the cirrhotic liver. In contrast, the expression levels of albumin and CRP were significantly lower in the liver tissue obtained from the BDL rat model than in the normal liver. The CRP level was correlated with the expression of albumin in hepatocytes treated with LCA and siRNA-CRP. Tube formation was significantly decreased in HUVECs when they were treated with LCA or a combination of LCA and siRNA-CRP. Conclusion CRP seems to be involved in the abnormal formation of vessels in hepatic disease, and so it could be a useful diagnostic marker for hepatic disease

Detection of ureaplasmas by the polymerase chain reaction in the amniotic fluid of patients with cervical insufficiency

Aims: The purpose of this study was to determine the clinical significance of detecting microbial footprints of ureaplasmas in amniotic fluid (AF) using specific primers for the polymerase chain reaction (PCR) in patients presenting with cervical insufficiency. Methods: Amniocentesis was performed in 58 patients with acute cervical insufficiency (cervical dilatation, >= 1.5 cm) and intact membranes, and without regular contractions (gestational age, 16-29 weeks). AF was cultured for aerobic and anaerobic bacteria as well as genital mycoplasmas. Ureaplasmas (Ureaplasma urealyticum and Ureaplasma parvum) were detected by PCR using specific primers. Patients were divided into three groups according to the results of AF culture and PCR for ureaplasmas: those with a negative AF culture and a negative PCR (n = 44), those with a negative AF culture and a positive PCR (n = 10), and those with a positive AF culture regardless of PCR result (n = 4). Results: 1) Ureaplasmas were detected by PCR in 19.0% (11/58) of patients, by culture in 5.2% (3/58), and by culture and/or PCR in 22.4% (13/58); 2) Among the 11 patients with a positive PCR for ureaplasmas, the AF culture was negative in 91% (10/11); 3) Patients with a negative AF culture and a positive PCR for ureaplasmas had a significantly higher median AF matrix metalloproteinase-8 (MMP-8) concentration and white blood cell (WBC) count than those with a negative AF culture and a negative PCR (P < 0.001 and P < 0.05, respectively); 4) Patients with a positive PCR for ureaplasmas but a negative AF culture had a higher rate of spontaneous preterm birth within two weeks of amniocentesis than those with a negative AF culture and a negative PCR (P < 0.05 after adjusting for gestational age at amniocentesis); 5) Of the patients who delivered within two weeks of amniocentesis, those with a positive PCR for ureaplasmas and a negative AF culture had higher rates of histologic amnionitis and funisitis than those with a negative AF culture and a negative PCR (P < 0.05 after adjusting for gestational age at amniocentesis, for each); 6) However, no significant differences in the intensity of the intra-amniotic inflammatory response and perinatal outcome were found between patients with a positive AF culture and those with a negative AF culture and a positive PCR. 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