Alexandre Yokochi

Structural and Synthetic Investigations of Tanikolide Dimer, a SIRT2 Selective Inhibitor, and Tanikolide Seco Acid from the Madagascar Marine Cyanobacterium Lyngbya majuscula

Tanikolide seco-acid 2 and tanikolide dimer 3, the latter a novel and selective SIRT2 inhibitor, were isolated from the Madagascar marine cyanobacterium Lyngbya majuscula. The structure of 2, isolated as the pure R enantiomer, was elucidated by X-ray experiment in conjunction with NMR and optical rotation data, whereas the depside molecular structure of 3 was initially thought to be a meso compound as established by NMR, MS, and chiral HPLC analyses. Subsequent total synthesis of the three tanikolide dimer stereoisomers 4, 5, and ent-5, followed by chiral GC-MS comparisons with the natural product, showed it to be exclusively the R,R-isomer 5. Tanikolide dimer 3 (= 5) inhibited SIRT2 with an IC(50) = 176 nM in one assay format and 2.4 microM in another. Stereochemical determination of symmetrical dimers such as compound 3 pose intriguing and subtle questions in structure elucidation and, as shown in the current work, are perhaps best answered in conjunction with total synthesis.

Gone with the wind: innovative hydrogen/fuel cell electric vehicle infrastructure based on wind energy sources

The development of sustainable, clean, and efficient transportation systems is a critical factor for the improvement of overall air quality and the reduction of the nations dependence on diminishing domestic resources and imported fuels. This article presents the development issues for an innovative fuel cell electric vehicle (EV) infrastructure and bidirectional grid connection, derived from renewable and clean energy sources, with a focus on wind energy. The effective use of wind power to drive water electrolysis plants to produce hydrogen for advanced fuel-cell EV is also illustrated in this paper.

A methodology to enable wind farm participation in automatic generation control using energy storage devices

Over the last decade, wind penetration has increased to the point where its variable nature is adding considerable stress and threatening the stability of the power systems in which it is included. In order to continue growth, wind farms will need to have the ability to participate in the same grid frequency regulation as normal generating sources. The goal of this research is to explore the use of energy storage devices to provide wind farms with a methodology to regulate their power output and grid frequency. With energy storage, this research aims to allow wind farms to participate in automatic generation control (AGC). Software simulations were performed to design an advanced energy storage controller that will allow the maximum dispatchability. A comprehensive in-lab grid was constructed to produce experimental results for this work and the equipment was used to evaluate the performance of the advanced energy storage controller. The first stage of this research aims to use super-capacitors to balance rapid excursions in frequency and wind power output while the second stage of this research will preliminarily explore the use of a zinc-bromine flow cell battery for medium-scale, sustained excursions in frequency and wind power output as well as reducing area control error (ACE). Results show that wind farms are capable of participation in AGC with the addition of an energy storage device, but the amount of participation is heavily reliant on the amount of energy storage available.

Hybrid thermoelectric conversion for enhanced efficiency in mobile platforms

Hybrid thermoelectric conversion (HTC) has been used as a means to improve the efficiency of high performance mobile computing systems. HTC utilizes the thermal margin in the cooling solution, when the electronic component is not fully active, to integrate a thermoelectric (TE) module into the heat dissipation path for energy scavenging. When the component is driven to its junction temperature limit through a heavy workload, the same TE module is switched to refrigeration mode to provide additional cooling headroom for improved performance. A set of semi-realistic system usage assumptions and parameters has been utilized for the evaluation of HTC in system environments. Results from finite-element analysis (FEA) simulation of the topology and full TE characterization are presented. Common TE models are then used to build an iterative system solver to estimate up to 10% system efficiency benefit from HTC integration using characterized off-the-shelf TE components.

Diffusion of dissolved ions from wet silica sol–gel monoliths: Implications for biological encapsulation

Divalent nickel (Ni(2+)), Cu(II)EDTA, methyl orange, and dichromate were used to investigate diffusion from hydrated silica sol-gel monoliths. The objective was to examine diffusion of compounds on a size regime relevant to supporting biological components encapsulated within silica gel prepared in a biologically compatible process space with no post-gelation treatments. With an initial sample set, gels prepared from tetraethoxysilane were explored in a factorial design with Ni(2+) as the tracer, varying water content during hydrolysis, acid catalyst present during hydrolysis, and the final concentration of silica. A second sample set explored diffusion of all four tracers in gels prepared with aqueous silica precursors and a variety of organically modified siloxanes. Excluding six outliers which displayed significant syneresis, the mean diffusion constant (D(gel)) across the entire process space of sample set 1 was 2.42×10(-10) m(2) s(-1); approximately 24% of the diffusion coefficient of Ni(2+) in unconfined aqueous solution. In sample set 2, the tracer size and not gel hydrophobicity was the primary determinant of changes in diffusion rates. A strong linear inverse correlation was found between tracer size and the magnitude of D(gel). Based on correlation with the tracers used in this investigation, the characteristic 1-h diffusion distance for carbonate species relevant to supporting active phototrophic organisms was approximately 1.5mm. These results support the notion that silica sol-gel formulations may be optimized for a given biological entity of interest with manageable impact to the diffusion of small ions and molecules.

In-lab research grid for optimization and control of wind and energy storage systems

The variability of wind power limits its grid penetration and increases costs. At high penetration levels, the variable output of wind requires utilities to dedicate much of their available reserve generation capacity to accommodate this variability. This paper presents research on improving wind energy integration through more effective coordination of traditional generation resources and energy storage systems (including analysis and control) that can optimize wind energy production while also increasing the predictability of wind farm output. This advanced research includes comprehensive simulations and experimental lab-grid implementation including renewable installations, traditional generation sources, energy storage technologies, power electronic converter control, and representative loads.

Innovative hydrogen/fuel cell electric vehicle infrastructure based on renewable energy sources

The development of sustainable, clean and efficient transportation systems is a critical factor for the improvement of overall air quality, and to reduce the nations dependence on diminishing domestic resources and imported fuels. Transportation accounts for one-third of all energy use and carbon emissions in the US, primarily from personal vehicles, constituting one of the biggest challenges for reducing emissions of greenhouse gases. This paper presents the development issues for an innovative fuel cell electric vehicle infrastructure and bi-directional grid connection, derived from renewable and clean energy sources.

Effect of packing fraction on ferromagnetic resonance in NiFe2O4 nanocomposites

Magnetic nanocomposites, composed of magnetic nanoparticles in an insulating matrix, can have properties not achievable in bulk, single-phase materials. This work reports on ferromagnetic resonance (FMR) measurements as a tool to investigate the internal magnetic field in nanocomposite samples of varying particle packing fractions. The ferromagnetic resonance frequency changes with particle packing fraction due to increased inter-particle interaction and demagnetizing field within the sample. Experimental results obtained on NiFe2O4 nanocomposite samples are compared to published theoretical models, and found to be consistent with the predicted trends. Extrapolation of the results to the limit of isolated particles indicates an average internal anisotropy field of 0.041 T for the NiFe2O4 nanoparticles.

Development of an option in Nanotechnology: Elements of Student learning

The development of an Nanotechnology Processes Option for chemical engineers and other students in the School of Chemical, Biological, and Environmental Engineering at Oregon State University is presented. The curricular development attends to content, pedagogy, and different types of knowledge. Assessment results based on Shavelsons cognitive model and plans to weave in a strand that encompasses environmental and human health in nanotechnology are summarized.

Ferromagnetic resonance study on NiFe 2 O 4 nanocomposites

NiFe2O4 nanocomposites were characterized by a coplanar waveguide ferromagnetic resonance (FMR) measurement setup. Ferromagnetic resonance fields were analyzed to determine the internal magnetic field in the samples. The effects of sample orientation and particle packing fraction on the FMR behavior are investigated. The results are found to agree with theoretical predictions on high frequency properties of magnetic nanocomposites.