Application Of Data Mining For Reverse Osmosis Process In Seawater Desalination

Reverse osmosis (RO) membrane process has been considered a promising technology for water treatment and desalination. However, it is difficult to predict the performance of pilot- or full-scale RO systems because numerous factors are involved in RO performance, including variations in feed water (quantity, quality, temperature, etc), membrane fouling, and time-dependent changes (deteriorations). Accordingly, this study intended to develop a practical approach for the analysis of operation data in pilot-scale reverse osmosis (RO) processes. Novel techniques such as artificial neural network (ANN) and genetic programming (GP) technique were applied to correlate key operating parameters and RO permeability statistically. The ANN and GP models were trained using a set of experimental data from a RO pilot plant with a capacity of 1,000 m3/day and then used to predict its performance. The comparison of the ANN and GP model calculations with the experiment results revealed that the models were useful for analyzing and classifying the performance of pilot-scale RO systems. The models were also applied for an in-depth analysis of RO system performance under dynamic conditions

Tuning Single-Molecule Conductance by Controlled Electric Field-Induced trans-to-cis Isomerisation

External electric fields (EEFs) have proven to be very efficient in catalysing chemical reactions, even those inaccessible via wet-chemical synthesis. At the single-molecule level, oriented EEFs have been successfully used to promote in situ single-molecule reactions in the absence of chemical catalysts. Here, we elucidate the effect of an EEFs on the structure and conductance of a molecular junction. Employing scanning tunnelling microscopy break junction (STM-BJ) experiments, we form and electrically characterize single-molecule junctions of two tetramethyl carotene isomers. Two discrete conductance signatures show up more prominently at low and high applied voltages which are univocally ascribed to the trans and cis isomers of the carotenoid, respectively. The difference in conductance between both cis-/trans- isomers is in concordance with previous predictions considering pi-quantum interference due to the presence of a single gauche defect in the trans isomer. Electronic structure calculations suggest that the electric field polarizes the molecule and mixes the excited states. The mixed states have a (spectroscopically) allowed transition and, therefore, can both promote the cis-isomerization of the molecule and participate in electron transport. Our work opens new routes for the in situ control of isomerisation reactions in single-molecule contacts

Mechanistic investigations of silylcarbinol rearrangements and use of a sigmatropic rearrangement for the stereoselective synthesis of polypropionates.

Silylcarbinols generated from the 1,2-addition of dimethyl(phenyl)silyllithium to cyclic $\alpha,\beta$-unsaturated ketones were found to undergo acid or base catalyzed rearrangements, depending upon the substitution pattern of the substrate. The $\alpha,\beta$-unsaturated silylcarbinols which contain an alkoxy group at the $\alpha$ carbon, have been shown to undergo silicon rearrangement under mildly acidic conditions to provide cyclic $\alpha$-alkoxyenol silyl ethers. The mechanism of this novel rearrangement has been proposed to be an acid-catalyzed 1,2-silyl group migration, followed by a thermal rearrangement of the resulting $\beta$-ketosilanes to give the $\alpha$-alkoxyenol silyl ethers, based on the isolation of intermediates, and on kinetic data. On the other hand, cyclic $\alpha,\beta$-unsaturated silylcarbinols which have an alkyl substituent at the $\alpha$ carbon, follow a base-catalyzed rearrangement to the corresponding silyl enol ethers. This Brook rearrangement has been shown to be an efficient method for the regiospecific generation of cyclic silyl enol ethers. The second part of the thesis describes a concise and highly stereoselective method for the generation of polypropionates, many of which are naturally occurring substances with biological and medicinal importance. The conjugate addition of lithium dimethylcuprate to 2-(2-buten-1-yloxy)-5-methyl-2-cyclopenten-1-one in the presence of trimethylsilyl trifluoromethanesulfonate, and a subsequent Claisen rearrangement of the resulting silyl enol ether, followed by desilylation provides (2R\sp*,2\sp\prime R\sp*,3S\sp*,5R\sp*)-2-(3-buten-2-yl)-3,5-dimethyl-2-hydroxycyclopentanone in high yield. This cyclic hydroxyketone intermediate was then efficiently transformed into the syn,syn-trimethyl-substituted carbon chain, (2R\sp*,4S\sp*,6R\sp*)-5-oxo-2,4,6-trimethyl-7-octen-1-al. Thus, this highly stereoselective method for the generation of a syn,syn-trimethyl-substituted polypropionate has been applied to the total synthesis of ($\pm$)-siphonarienone, which contains identical relative stereochemistry. ($\pm$)-Siphonarienone, which was isolated from Siphonaria grisea in 1990, has been synthesized stereoselectively from (2R\sp*,4S\sp*,6R\sp*)-5-oxo-2,4,6-trimethyl-7-octen-1-al in 6 steps in 17% overall yield.Ph.D.ChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/103096/1/9303762.pdfDescription of 9303762.pdf : Restricted to UM users only

Identification of Causal Relationship between Attitudinal Factors and Intention to Use Transportation Mode

Based on the theory of planned behavior, this study identifies the causal relationship between attitudinal factors and intention to use transportation mode. A structural equation model was developed based on twelve hypotheses. The main findings and implications of this study are as follows. First, people who want to express themselves through cars have a high intention to use personal vehicles, and they purchase cars for this purpose. If the shared vehicle service provides a vehicle rental that reflects individual tastes, those who want to own the vehicle will use the shared vehicle. This could be a solution to the parking problem. Second, those who perceive travel as a disutility have a low intention to use public transportation. If fare discounts are applied when transferring public transportation and micro-mobility, it is expected that the use of public transportation will increase due to reduction of access time for public transportation. Third, people who like to drive have a high intention to use personal vehicles and micro-mobility. Providing space for driving cars as a leisure activity may be one of the ways to prevent traffic accidents that may occur in the future due to a mixed flow of autonomous vehicles and conventional vehicles

Identification of Causal Relationship between Attitudinal Factors and Intention to Use Transportation Mode

Based on the theory of planned behavior, this study identifies the causal relationship between attitudinal factors and intention to use transportation mode. A structural equation model was developed based on twelve hypotheses. The main findings and implications of this study are as follows. First, people who want to express themselves through cars have a high intention to use personal vehicles, and they purchase cars for this purpose. If the shared vehicle service provides a vehicle rental that reflects individual tastes, those who want to own the vehicle will use the shared vehicle. This could be a solution to the parking problem. Second, those who perceive travel as a disutility have a low intention to use public transportation. If fare discounts are applied when transferring public transportation and micro-mobility, it is expected that the use of public transportation will increase due to reduction of access time for public transportation. Third, people who like to drive have a high intention to use personal vehicles and micro-mobility. Providing space for driving cars as a leisure activity may be one of the ways to prevent traffic accidents that may occur in the future due to a mixed flow of autonomous vehicles and conventional vehicles

1,2-Addition of dimethyl(phenyl)silyllithium to cyclic [alpha],[beta]-unsaturated ketones and regiospecific generation of cyclic silyl enol ethers through brook rearrangement of the 1,2-addition products

A highly convenient two-step sequence for the regiospecific synthesis of cyclic silyl enol ethers has been developed involving the 1,2-addition of dimethyl(phenyl)silyllithium to cyclic [alpha],[beta]-unsaturated ketones followed by the treatment of the resulting silyl carbinols with a catalytic amount of NaH in THF at 25 [deg]C.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28922/1/0000759.pd

Finance, Production Efficiency,and Growth : Evidence from the Korean Manufacturing Industries

Numerous studies have focused on the development of financial market as a driving force in economic growth. We find that the provision of financial services enhances production efficiency, and thereby promotes economic growth. Applying the stochastic frontier production function approach to the panel data of the Korean regional manufacturtng industries, we show that an increase in financial services is associated with the reduction in technical inefficiency. It implies that the supply of financial services is essential to economic growth

Bis-sulfonic Acid Ionic Liquids for the Conversion of Fructose to 5-Hydroxymethyl-2-furfural

Homogenous bis-sulfonic acid ionic liquids (1 mol equiv.) in DMSO (10 mol equiv.) at 100 °C efficiently mediated the conversion of D-fructose into 5-hydroxymethyl-2-furfural in 75% isolated yield, which was roughly a 10% increment compared to the case of the mono-sulfonic acid ionic liquids

Oxo-Carotenoids as Efficient Superoxide Radical Scavengers

Oxo-carotenoids containing conjugated carbonyl groups in their chains were designed to be more efficient superoxide radical scavengers than natural carotenoids, β-carotene and canthaxanthin. A practical chain-extension method for polyene dials (e.g., crocetin dial) was also proposed based on Horner–Wadsworth–Emmons olefination. Double aldol condensation between polyene dials and acetophenones with ring substituents produced oxo-carotenoids with substituted benzene rings. The antioxidant activity of oxo-carotenoids was measured using DPPH (radical) and ABTS (cationic radical) scavenging assays and compared with the analysis with the superoxide (anionic radical) probe. An effective conjugation length by carbon–carbon double bonds is important to provide superior antioxidant activity for oxo-carotenoids, regardless of the type of radical probe used in the assay. Increasing electron density is favorable to strong antioxidant activity in DPPH, and the phenol group is favored in ABTS, whereas electron deficient oxo-carotenoids are very potent in the superoxide radical assay. All oxo-carotenoids exhibited 105~151% better superoxide radical scavenging activity compared to beta-carotene (100%), whereas 38~155% in DPPH and 16~96% in ABTS radical scavenging activities were observed