Nanostructured Non-precious Metal Electrocatalysts for Oxygen Reduction Reaction in Alkaline Solutions

Battery Science and TechnologyAdvanced electrical energy storage systems play a vital role in efficient use of electricity in micro-grids or smart-grids to bridge the gaps between demand and supply, especially for renewable energy sources of intermittent and cyclic nature (e.g., solar, wind, and geothermal energy). In the transportation sector, the transition from the current hybrid electric vehicles to all-electric vehicles hinges critically on the development of electrical energy storage systems with dramatically improved energy and power density, durability, and reduced cost. Therefore, new electrochemical systems with higher energy density are being sought, and metal-air batteries with conversion chemistry have the greatest potential to offer the highest energy density and to meet the ever-increasing demands for clean and secure energy. However, the commercialization of metal-air batteries depends critically on the creation of novel air-breathing electrodes with much higher levels of functionality and performance. For example, efficient catalysts for oxygen reduction reaction (ORR) at the air-electrode are yet to be developed to significantly reduce the polarization loss in metal-air batteries. In this thesis, I started with a brief overview of the critical issues relevant to overall zinc-air batteries in chapter 1 and then discussed fundamental aspects of ORR and highlight some recent advancement in the development of non-precious catalysts for ORR in zinc-air batteries, including transition metal oxides, low-dimensional carbon-based structures, and other catalysts in chapter 2. Finally, I introduced my research papers studying electrocatalysts for ORR in alkaline solutions in the rest chapters.ope

A Smart IoT Device for Detecting and Responding to Earthquakes

The advancement of hardware and software technologies makes it possible to use smartphones or Internet of things for monitoring environments in realtime. In recent years, much effort has been made to develop a smartphone based earthquake early warning system, where low-cost acceleration sensors inside a smartphones are used for capturing earthquake signals. However, because a smartphone comes with a powerful CPU, spacious memory, and several sensors, it is waste of such resources to use it only for detecting earthquakes. Furthermore, because a smartphone is mostly in use during the daytime, the acquired data cannot be used for detecting earthquakes due to human activities. Therefore, in this article, we introduce a stand-alone device equipped with a low-cost acceleration sensor and least computing resources to detect earthquakes. To that end, we first select an appropriate acceleration sensor by assessing the performance and accuracy of four different sensors. Then, we design and develop an earthquake alert device. To detect earthquakes, we employ a simple machine learning technique which trains an earthquake detection model with daily motions, noise data recorded in buildings, and earthquakes recorded in the past. Furthermore, we evaluate the four acceleration sensors by recording two realistic earthquakes on a shake-table. In the experiments, the results show that the developed earthquake alert device can successfully detect earthquakes and send a warning message to nearby devices, thereby enabling proactive responses to earthquakes

Analysis of in the Uterine Endometrium of Pigs Carrying Somatic Cell Nuclear Transfer Cloned Embryos

Somatic cell nuclear transfer (SCNT) is a useful tool for animal cloning, but the efficiency of producing viable offspring by SCNT is very low. To improve this efficiency in the production of cloned pigs, it is critical to understand the interactions between uterine function and cloned embryos during implantation. Lysophosphatidic acid (LPA) is a lipid mediator that plays an important role in the establishment of pregnancy in pigs; however, LPA production in the uterine endometrium of pigs carrying SCNT-cloned conceptuses has not been determined. Therefore, we investigated expression of ENPP2, an LPA-generating enzyme, in the uterine endometrium of gilts with conceptuses derived from SCNT during the implantation period. Uterine endometrial tissue and uterine flushing were obtained from gilts carrying SCNT-derived conceptuses and from gilts carrying conceptuses resulting from natural mating on d 12 of pregnancy. Our results demonstrated no difference in the level of ENPP2 mRNA expression in the uterine endometrium between gilts carrying SCNT-derived conceptuses and gilts carrying naturally-conceived conceptuses, but secretion of ENPP2 protein into the uterine lumen did decrease significantly in pigs with SCNT-derived conceptuses. These results indicate that expression and secretion of ENPP2, which are critical for appropriate LPA production and successful pregnancy, are dysregulated in the uterine endometrium of pigs carrying SCNT-derived conceptuses

Microarray Analysis of Gene Expression in the Uterine Endometrium during the Implantation Period in Pigs

During embryo implantation in pigs, the uterine endometrium undergoes dramatic morphological and functional changes accompanied with dynamic gene expression. Since the greatest amount of embryonic losses occur during this period, it is essential to understand the expression and function of genes in the uterine endometrium. Although many reports have studied gene expression in the uterine endometrium during the estrous cycle and pregnancy, the pattern of global gene expression in the uterine endometrium in response to the presence of a conceptus (embryo/fetus and associated extraembryonic membranes) has not been completely determined. To better understand the expression of pregnancy-specific genes in the endometrium during the implantation period, we analyzed global gene expression in the endometrium on day (D) 12 and D15 of pregnancy and the estrous cycle using a microarray technique in order to identify differentially expressed endometrial genes between D12 of pregnancy and D12 of the estrous cycle and between D15 of pregnancy and D15 of the estrous cycle. Results showed that the global pattern of gene expression varied with pregnancy status. Among 23,937 genes analyzed, 99 and 213 up-regulated genes and 92 and 231 down-regulated genes were identified as differentially expressed genes (DEGs) in the uterine endometrium on D12 and D15 of pregnancy compared to D12 and D15 of the estrous cycle, respectively. Functional annotation clustering analysis showed that those DEGs included genes involved in immunity, steroidogenesis, cell-to-cell interaction, and tissue remodeling. These findings suggest that the implantation process regulates differential endometrial gene expression to support the establishment of pregnancy in pigs. Further analysis of the genes identified in this study will provide insight into the cellular and molecular bases of the implantation process in pigs

Anomalous Pseudocapacitive Behavior of a Nanostructured, Mixed-Valent Manganese Oxide Film for Electrical Energy Storage

While pseudocapacitors represent a promising option for electrical energy storage, the performance of the existing ones must be dramatically enhanced to meet today's ever-increasing demands for many emerging applications. Here we report a nanostructured, rnixed-valent manganese oxide film that exhibits anomalously high specific capacitance (similar to 2530 F/g of manganese oxide, measured at 0.61 A/g in a two-electrode configuration with loading of active materials similar to 0.16 mg/cm(2)) while maintaining excellent power density and cycling life. The dramatic performance enhancement is attributed to its unique mixed-valence state with porous nanoarchitecture, which may facilitate rapid mass transport and enhance surface double-layer capacitance, while promoting facile redox reactions associated with charge storage by both Mn and O sites, as suggested by in situ X-ray absorption spectroscopy (XAS) and density functional theory calculations. The new charge storage mechanisms (in addition to redox reactions of cations) may offer critical insights to rational design of a new-generation energy storage devices.close624