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Pergamon Press ; Elsevier Science Ltd 2015 COMPUTERS & MATHEMATICS WITH APPLICATIONS - Vol.69 No.10
Newton's method with first-order system least squares (FOSLS) finite element method has been widely used to approximately solve a system of nonlinear partial differential equations (Adler et al., 2010 [9], Codd et al., 2003 [10], Manteuffel et al., 2006 [11]). In this paper, we propose to use the first order system LL<SUP>*</SUP> method to find a correction in each Newton's iteration which provides an L<SUP>2</SUP>-approximation of the second-order semi-linear elliptic partial differential equations while the typical Newton-FOSLS method providesH<SUP>1</SUP>-approximations. The numerical tests have been conducted to validate the theory.
Sea level periodic change and its impact on submarine groundwater discharge rate in coastal aquifer
Lee, E.,Hyun, Y.,Lee, K.K. Academic Press in association with the Estuarine a 2013 Estuarine, coastal and shelf science Vol.121 No.-
This study focused on the interaction between groundwater and seawater and the effect of temporal scale of sea level fluctuation on submarine groundwater discharge (SGD) rate. The numerical code FEFLOW (Diersch, 2005) was used to evaluate the influence of periodic changes in sea level on an increase in SGD at various time scales from diurnal to glacial cycles. Simulation results showed that not only amplitude but also period of the sea level fluctuation controls total amount of SGD. The increase ratio of recirculated submarine groundwater discharge (RSGD) was found to generally be proportional to the amplitude of sea level and the square root of specific storage of an aquifer while inversely proportional to the square root of hydraulic conductivity of an aquifer and period of sea level fluctuation. A nondimensional number P<SUP>*</SUP> that incorporates combined effect of sea level oscillation and aquifer properties is used to represent the magnitude of periodic forcing from sea boundary into an aquifer as a mechanism for enhancement of RSGD. Simulation results demonstrate that increase ratios of RSGD are well fitted by an exponential curve as a function of P<SUP>*</SUP>, and variations in RSGD occur only when P<SUP>*</SUP> exceeds a critical number. The dimensionless inland recharge rate, where recharge rate is divided by hydraulic conductivity, was shown to be important in determining the critical number. This implies that sea level fluctuation does not lead to enhancement of RSGD until the specified condition is reached, and groundwater recharge rate and aquifer hydraulic conductivity are the key factors controlling the increase of RSGD.
Lee, E.,Lee, S.,Park, J.,Kim, Y.,Cho, J. Copernicus GmbH 2013 Drinking water engineering and science Vol.6 No.2
<P><p><strong>Abstract.</strong> Since trace organic compounds such as pharmaceuticals in surface water have been a relevant threat to drinking water supplies, in this study removal of pharmaceuticals and transformation of pharmaceuticals into metabolites were investigated in the main source of micropollutants such as WWTPs and engineered constructed wetlands. Pharmaceuticals were effectively removed by different WWTP processes and wetlands. Pharmaceutical metabolites with relatively low log <i>D</i> value were resulted in the low removal efficiencies compared to parent compounds with relatively high log <i>D</i> value, indicating the stability of metabolites. And the constructed wetlands fed with wastewater effluent were encouraged to prevent direct release of micropollutants into surface waters. Among various pharmaceuticals, different transformation pattern of ibuprofen was observed with significant formation of 1-hydroxy-ibuprofen during biological treatment in WWTP, indicating preferential biotransformation of ibuprofen. Lastly, transformation of pharmaceuticals depending on their structural position was investigated in terms of electron density, and, the electron rich C<sub>1</sub> = C<sub>2</sub> bond of carbamazepine was revealed as an initial transformation position.</p> </P>
Metallacycles derived from metal complexes of exo-coordinated macrocyclic ligands
Lee, E.,Lee, S.Y.,Lindoy, L.F.,Lee, S.S. Elsevier Publishing Company 2013 Coordination chemistry reviews Vol.257 No.21
The assembly of metallacyclic structures incorporating exo-coordinated macrocyclic ligand components is reviewed. The exo-coordination approach provides a means for building extended cyclic assemblies and contrasts with the use of conventional endocyclic macrocyclic coordination which generally results in metal-in-cavity products. The approach, which depends on the availability of one or more donor atoms bearing electron lone pairs that are oriented exo to their macrocyclic cavity, has been employed to produce a range of diverse metallacyclic structures; examples of such metallo-assemblies displaying cyclic dimeric, trimeric, tetrameric, and hexameric topologies are presented.
Lee, E.,Moon, J.W.,Wang, X.,Kim, C.,Li, S.,Shin, B.K.,Jung, W.,Kim, H.K.,Kim, H.K.,Lee, J.Y. W. B. Saunders Co ; Centrum Philadelphia 2015 Human pathology Vol.46 No.8
Adenocarcinoma (AC) and squamous cell carcinoma (SCC) of non-small cell lung carcinoma (NSCLC) have different clinical presentations, morphologies, treatments, and prognoses. Recent studies suggested that fundamental genetic alterations related to carcinogenesis of each tumor type may be different. In this study, we investigated the genomic alterations of 47 primary NSCLC samples (22 ACs and 25 SCCs) as well as the corresponding normal tissue using array comparative genomic hybridization. Frequent copy number alterations (CNAs), which were identified in more than 68% of all of the cases, were evaluated in each subtype (SCC and AC), and a CNA signature was established. Among these CNAs, 37 genes from the SCCs and 15 genes from the ACs were located in a region of gain, and 4 genes from the SCCs and 13 genes from the ACs were located in a region of loss. The most frequent gain was located on 3q26-29 including the gene TP63 in SCCs and 7q11.23 and 7q36.3 in ACs. Moreover, we identified 3 genetically distinct groups (group I [16 SCC] with CNA signature of SCC; group II [7 SCC + 8 AC], which has a genetically distinctive CNA signature from SCC and AC; and group III [2 SCC + 14 AC] with CNA signature of AC) by gene clustering extracted from CNAs, which are associated with a prognosis. The present study contributed to the molecular characterization of AC and SCC of NSCLC and showed a subtype of tumor that has a unique genetic CNA signature. However, further study about the significance of these 3 distinct groups and their usefulness as a diagnostic marker of identified CNAs is necessary.
Lee, E.,Shon, H.K.,Cho, J. Elsevier Scientific Pub. Co 2014 Journal of hazardous materials Vol.276 No.-
Overall photodegradation of pharmaceuticals, personal care products (PPCPs) and pharmaceutical metabolites were investigated in order to evaluate their photochemical fate in aquatic environments in various natural organic matter (NOM) enriched solutions. Tested PPCPs exhibited different rates of loss during direct and indirect photolysis. Here, only ultraviolet (UV) light source was used for direct photolysis and UV together with <SUP>3</SUP>DOM<SUP>*</SUP>for indirect photolysis. Diclofenac and sulfamethoxazole were susceptible to photodegradation, whereas carbamazepine, caffeine, paraxanthine and tri(2-chloroethyl) phosphate (TCEP) showed low levels of photodegradation rate, reflecting their conservative photoreactivity. During indirect photodegradation, in contrast to the hydrophilic autochthonous NOM, allochthonous NOM with relatively high molecular weight (MW), specific ultraviolet absorbance (SUVA) and hydrophobicity (e.g., Suwannee River humic acid (SRHA)) revealed to significantly inhibit the photolysis of target micropollutants. The presence of Typha wetland NOM enhanced the indirect photolysis of well-known conservative micopollutants (carbamazepine and paraxanthine). And atenolol, carbamazepine, glimepiride, and N-acetyl-sulfamethoxazole were found to be sensitive to the triplet excited state of dissolved organic matter (<SUP>3</SUP>DOM<SUP>*</SUP>) with Typha wetland NOM under deoxygenated condition. This suggests that photolysis in constructed wetlands connected to the wastewater treatment plant can enhance the degradation of some anthropogenic micropollutants by the interaction with <SUP>3</SUP>DOM<SUP>*</SUP> in wetlands.
Pd-Ni hydrogen sponge for highly sensitive nanogap-based hydrogen sensors
Lee, E.,Lee, J.,Noh, J.S.,Kim, W.,Lee, T.,Maeng, S.,Lee, W. Pergamon Press ; Elsevier Science Ltd 2012 International journal of hydrogen energy Vol.37 No.19
We have successfully fabricated sub-100 nm nanogaps in Pd-Ni alloy thin films on an elastomeric substrate by simple stretching. The nanogaps-containing Pd-Ni films were utilized as hydrogen-sensing sponges and their performance was demonstrated to dominate over the performance of similar mobile thin films comprised of pure Pd in major aspects such as the response time, sensitivity in high H<SUB>2</SUB> concentrations, and H<SUB>2</SUB> detection limit. Notably, Pd<SUB>87.5</SUB>Ni<SUB>12.5</SUB> hydrogen sensing sponges showed ultra-high sensitive and reversible On-Off behaviors and low detection limit of ~100 ppm, which were attributed to the reduced nanogap width and the enhanced volume expandability of Pd-Ni lattice. The effects of Ni added to Pd and a search for an optimum Ni concentration were also systematically studied.