Kopsifolines A, B, and C, indole alkaloids with a novel hexacyclic carbon skeleton from Kopsia

Three indole alkaloids, viz., kopsifolines A, B, and C, characterized by a novel carbon skeleton, were obtained from a Malayan Kopsia species and the structures established by spectroscopic analysis.     

Modeling manganese removal in chelating polymer-assisted membrane separation systems for water treatment

The removal of manganese from groundwater, using water-soluble chelating polymers such as polyacrylic acid (PAA) in combination with ultrafiltration (UF), was investigated. The effects of the solution pH and polymer dosages on the manganese removal were evaluated, and the removal efficiency was modeled considering the relevant chemical equilibria. In the absence of polymer, manganese removal with UF membranes alone was negligible at acidic pH values, but the removal increased substantially when polyacrylic acid (PAA) was added to the feed solution. The increase can be attributed to the formation of Mn²⁺–PAA chelates which are rejected by the membranes. A mathematical model was developed to explain this phenomenon based on chemical equilibria, including complex formation and precipitation. The chelation number (i.e., the number of carboxyl groups in the PAA binding to a single metal ion) and the equilibrium constants for metal–PAA chelation reactions were obtained by fitting experimental data at acidic pH in single-divalent metal systems. The model was able to predict Mn removal in chelation/UF systems at various pH levels and polymer dosages, and to account for the competitive interactions of PAA with the target (Mn²⁺) and background species (Ca²⁺, Mg²⁺) in multi-component systems. The predicted Mn removal efficiency was most sensitive to the chelation number.     

Highly sensitive signal detection of duplex dye-labelled DNA oligonucleotides in a PDMS microfluidic chip: confocal surface-enhanced Raman spectroscopic study

Rapid and highly sensitive detection of duplex dye-labelled DNA sequences in a PDMS microfluidic channel was investigated using confocal surface enhanced Raman spectroscopy (SERS). This method does not need either an immobilization procedure or a PCR amplification procedure, which are essential for a DNA microarray chip. Furthermore, Raman peaks of each dye-labelled DNA can be easily resolved since they are much narrower than the corresponding broad fluorescence bands. To find the potential applicability of confocal SERS for sensitive bio-detection in a microfluidic channel, the mixture of two different dye-labelled (TAMRA and Cy3) sex determining Y genes, SRY and SPGY1, was adsorbed on silver colloids in the alligator teeth-shaped PDMS microfluidic channel and its SERS signals were measured under flowing conditions. Its major SERS peaks were observable down to the concentration of 10(-11) M. In the present study, we explore the feasibility of confocal SERS for the highly sensitive detection of duplex dye-labelled DNA oligonucleotides in a PDMS microfluidic chip.     

Culture medium optimization for acetic acid production by a persimmon vinegar-derived bacterium

A new acetic acid-producing microorganism, Acetobacter sp. RKY4, was isolated from Korean traditional persimmon vinegar, and we optimized the culture medium for acetic acid production from ethanol using the newly isolated Acetobacter sp. RKY4. The optimized culture medium for acetic acid production using this microorganism was found to be 40 g/L ethanol, 10 g/L glycerol, 10 g/L corn steep liquor, 0.5 g/L MgSO₄·7H₂O, and 1.0 g/L (NH₄H₂PO₄. Acetobacter sp. RKY4 produced 47.1 g/L of acetic acid after 48 h of fermentation in a 250 mL Erlenmeyer flask containing 50 mL of the optimized medium.     

L-error estimate for the strongly damped extensible beam equations

L²-error estimates for finite-element Galerkin solutions for the strongly damped extensible beam equations are considered. The semidiscrete scheme and a fully discrete Galerkin scheme based on the Crank-Nicolson method are studied using appropriate projections. The corresponding stability analysis and error estimates are obtained.     

Relationship between ganglioside expression and anti-cancer effects of the monoclonal antibody against epithelial cell adhesion molecule in colon cancer

The human colorectal carcinoma-associated GA733 antigen epithelial cell adhesion molecule (EpCAM) was initially described as a cell surface protein selectively expressed in some myeloid cancers. Gangliosides are sialic acid-containing glycosphingolipids involved in inflammation and oncogenesis. We have demonstrated that treatment with anti-EpCAM mAb and RAW264.7 cells significant inhibited the cell growth in SW620 cancer cells, but neither anti-EpCAM mAb nor RAW264.7 cells alone induced cytotoxicity. The relationship between ganglioside expression and the anti- cancer effects of anti-EpCAM mAb and RAW264.7 was investigated by high-performance thin-layer chromatography. The results demonstrated that expression of GM1 and GD1a significantly increased in the ability of anti-EpCAM to inhibit cell growth in SW620 cells. Anti-EpCAM mAb treatment increased the expression of anti-apoptotic proteins such as Bcl-2, but the expression of pro-apoptotic proteins Bax, TNF-α, caspase-3, cleaved caspase-3, and cleaved caspase-8 were unaltered. We observed that anti-EpCAM mAb significantly inhibited the growth of colon tumors, as determined by a decrease in tumor volume and weight. The expression of anti-apoptotic protein was inhibited by treatment with anti-EpCAM mAb, whereas the expression of pro-apoptotic proteins was increased. These results suggest that GD1a and GM1 were closely related to anticancer effects of anti-EpCAM mAb. In light of these results, further clinical investigation should be conducted on anti-EpCAM mAb to determine its possible chemopreventive and/or therapeutic efficacy against human colon cancer.     

Synthesis of CuInS2-ZnS alloyed nanocubes with high luminescence

CuInS(2)-ZnS alloyed nanocubes with high luminescence were synthesized through a solution-based diffusion method.