• Carbon letters
• /
• v.12 no.3
• /
• pp.152-161
• /
• 2011

Activated carbon was prepared from pre-carbonized petroleum coke. Textural properties were determined from studies of the adsorption of nitrogen at 77 K and the surface chemistry was obtained using the Fourier-transform infrared spectrometer technique and the Boehm titration process. The adsorption of three aromatic compounds, namely phenol (P), p-nitrophenol (PNP) and benzoic acid (BA) onto APC in aqueous solution was studied in a batch system with respect to contact time, pH, initial concentration of solutes and temperature. Active carbon APC obtained was found to possess a high surface area and a predominantly microporous structure; it also had an acidic surface character. The experimental data fitted the pseudo-second-order kinetic model well; also, the intraparticle diffusion was the only controlling process in determining the adsorption of the three pollutants investigated. The adsorption data fit well with the Langmuir and Freundlich models. The uptake of the three pollutants was found to be strongly dependent on the pH value and the temperature of the solution. Most of the experiments were conducted at pH 7; the $pH_{(PZC)}$ of the active carbon under study was 5.0; the surface of the active carbon was negatively charged. The thermodynamic parameters evaluated for APC revealed that the adsorption of P was spontaneous and exothermic in nature, while PNP and BA showed no-spontaneity of the adsorption process and that process was endothermic in nature.

• Journal of the Korean Chemical Society
• /
• v.60 no.2
• /
• pp.137-143
• /
• 2016

Effective teaching and learning is a continuous process of monitoring and re-organization of teaching method, so to benefit both students and educators. Reflective journal writing is an effective method for students to reflect on their learning experience about a new concept or subject taught and at the same time enables educators to improve on their academic skills. In the present paper, we have examined and evaluated the effectiveness of the Uncritical Inference Test (UIT) that was conducted in our basic organic chemistry course through a systematic network built based on students’ reflective writing. From the data analysis, the UIT has benefited students in three dimensions, namely cognitive, affective and group learning domains. Moreover, the UIT activity instilled an active learning environment in organic chemistry classroom and deeper learning among chemistry students as shown in the collected data. In future, this activity could be adapted as a teaching method to enhance students’ critical thinking skills and question-asking capability in other teaching courses.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.9
• /
• pp.2753-2759
• /
• 2013

The aim of the present study is to explore the possibility of utilizing fly ash and loess, as alternative to activated carbon, for the adsorption of diazinon in water. Batch adsorption experiment was performed to evaluate the influences of various factors like initial concentration, contact time and temperature on the adsorption of diazinon. The adsorption data shows that fly ash is not effective for the adsorption of diazinon. The equilibrium data for both activated carbon and loess were fitted well to the Freundlich isotherm model. The pseudo-second-order kinetic model appeared to be the better-fitting model because it has higher $R^2$ compared to the pseudo-first-order kinetic model. The thermodynamic parameters such as free energy (${\Delta}G$), the enthalpy (${\Delta}H$) and the entropy (${\Delta}S$) were calculated. Contrary to loess, the ${\Delta}G$ values of activated carbon were negative at the studied temperatures. It indicates that the adsorption of diazinon by activated carbon is a favorable and spontaneous process. The positive ${\Delta}H$ values of activated carbon and loess suggest that the diazinon adsorption process is endothermic in nature. In addition, the positive ${\Delta}S$ values show that increased randomness occurs at the solid/solution surface during the adsorption of diazinon.

• BMB Reports
• /
• v.40 no.2
• /
• pp.226-231
• /
• 2007

Housekeeping genes are widely used as internal controls in a variety of study types, including real time RT-PCR, microarrays, Northern analysis and RNase protection assays. However, even commonly used housekeeping genes may vary in stability depending on the cell type or disease being studied. Thus, it is necessary to identify additional housekeeping-type genes that show sample-independent stability. Here, we used statistical analysis to examine a large human microarray database, seeking genes that were stably expressed in various tissues, disease states and cell lines. We further selected genes that were expressed at different levels, because reference and target genes should be present in similar copy numbers to achieve reliable quantitative results. Real time RT-PCR amplification of three newly identified reference genes, CGI-119, CTBP1 and GOLGAl, alongside three well-known housekeeping genes, B2M, GAPD, and TUBB, confirmed that the newly identified genes were more stably expressed in individual samples with similar ranges. These results collectively suggest that statistical analysis of microarray data can be used to identify new candidate housekeeping genes showing consistent expression across tissues and diseases. Our analysis identified three novel candidate housekeeping genes (CGI-119, GOLGA1, and CTBP1) that could prove useful for normalization across a variety of RNA-based techniques.

• Korean Journal of Medicinal Crop Science
• /
• v.9 no.4
• /
• pp.269-274
• /
• 2001

Two sesquiterpene lactones were isolated from the flowers of Chrysanthemum coronarium L. by silica gel chromatography and recrystalization. Their structures were determined using various spectroscopic data, and were identified as eudesmanolide derivatives douglanine and reynosin, respectively. This is reported for the first time in this plant. The cytotoxic activity of two compounds showed strong activities against human cancer cell lines such as A549, PC-3 and HCT 116.

• Analytical Science and Technology
• /
• v.8 no.4
• /
• pp.583-590
• /
• 1995

Pitch-based mesophase carbon fibers prepared at different temperatures were heat-treated at temperatures lower than those of the preparation and the electrochemical Li doping/undoping characteristics were evaluated in relation to the data of IR, mass, etc. Presence of surface hydroxyls were confirmed by FTIR for lower temperature sample which showed poor anode characteristics. Upon oxidative heating, removal of surface hydroxyls took place, resulting in a remarkable improvement of the electrode characteristics. At the same time, surface roughening took place, which was confirmed by SEM and double layer capacity measurements. In situ mass spectra obesrved during the heat-treatments showed gas evolution of $H_2O$, CO, $CO_2$, $C_2H_4$, and/or $H_2$ depending on the conditions. These data together with those of weight loss and conductivity provided us a valuable information in regard to the evaluation of the electrochemical characteristics.

• Carbon letters
• /
• v.7 no.4
• /
• pp.249-258
• /
• 2006

Treatment of water hyacinth with sulphuric acid produces carbonaceous materials that have been used to remove Cu(II) and Cd (II) ions from aqueous solutions. Untreated water hyacinth was also used for the subject of comparison. The textural properties of the carbonaceous materials were determined from nitrogen adsorption at 77 K. The optimum pH for the sorption of Cu (II) and Cd (II) ions on the investigated sorbents was determined. Dynamic adsorption measurements have been taken at 298 K whereas equilibrium measurements were carried out at 298, 313 and 323 K. The adsorption of nitrogen at 77 K on the untreated sample was too low and the surface areas of the treated samples 2, 3 and 4 were found between $70-208\;m^2/g$. The total pore volumes of these samples which were determined for the carbonaceous materials investigated were found to be 0.076-0.140 ml/g. The kinetic adsorption data of Cu (II) and Cd(II) were applicable to both pseudo - first and pseudo-second order but fit more the latter order. The equilibrium adsorption data were found to fit Freundlich and Langmiur equations. The values of DG, DH and DS are all negative indicating the feasibility and the spontaneous nature of the sorption of Cu (II) and Cd (II) ions by the sorbents investigated.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.7
• /
• pp.967-970
• /
• 2003

A new modified singular value decomposition method, piecewise polynomial truncated SVD (PPTSVD), which was originally developed to identify discontinuity of the earth's radial density function, has been used for large solvent peak suppression and noise elimination in nuclear magnetic resonance (NMR) signal processing. PPTSVD consists of two algorithms of truncated SVD (TSVD) and L₁ problems. In TSVD, some unwanted large solvent peaks and noise are suppressed with a certain soft threshold value, whereas signal and noise in raw data are resolved and eliminated in L₁ problems. These two algorithms were systematically programmed to produce high quality of NMR spectra, including a better solvent peak suppression with good spectral line shapes and better noise suppression with a higher signal to noise ratio value up to 27% spectral enhancement, which is applicable to multidimensional NMR data processing.

• Advances in environmental research
• /
• v.2 no.4
• /
• pp.309-321
• /
• 2013

High AA new high capacity sorbent for preconcentration and determination of nickel in environmental samples was synthesized. The sorbent was synthesized by copolymerization of allyl glaycidyl ether / imminodiacetic acid with N,N-dimethylacrylamide as functional monomers in the presence of N,N-bismethylenacryl amid as cross linker and characterized by Fourier transform infra red spectroscopy, elemental analysis, thermogravimetric analysis and scanning electron microscopy. A recovery of 93.6% was obtained for the metal ion with 0.1 M, sulfuric acid as the eluting agent. The sorption capacity of the functionalized sorbent was 55.9 $mgg^{-1}$. The equilibrium sorption data of Ni(II) on polymeric sorbent were analyzed using Langmuir, Freundlich, Temkin and Redlich.Peterson models. Based on equilibrium adsorption data the Langmuir, Freundlich and Temkin constants were determined 0.87 (L mg-1), 25.87 ($mgg^{-1}$) $(Lmg^{-1})^{1/n}$ and 171.4 ($Jmol^{-1}$) respectively at pH 4.5 and $20^{\circ}C$.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.9
• /
• pp.1346-1350
• /
• 2004

Pseudo-first order rate constants $(k_{obs})$ are reported for the following solvolyses in approximately isodielectric mixtures: 3- and 4-methoxybenzyl chloride, bromo- and chlorodiphenylmethane, and 4-chloro-, 4,4'-dichloro and 4-methyl-chlorodiphenylmethane in 0-80% v/v nitromethane-methanol mixtures; and bromo- and chlorodiphenylmethane and 4-methyl-chlorodiphenylmethane in various acetonitrile-methanol mixtures (in the range 0-50% v/v) at$25^{\circ}C.$ These data, and literature data for t-butyl halides (Cl, Br, and I), and for p-methoxybenzoyl chloride, show rate maxima in solvent compositions of ca. 30% aprotic cosolvent, explained by a stoichiometric solvent effect on electrophilic solvation. Linear relationships are observed between $(k_{obs})/[MeOH]^2$ and [AP]/[MeOH], where [AP] refers to the molar concentration of aprotic cosolvent. The results are consistent with competing third order contributions to $k_{obs}$, $k_{MM}[MeOH]^2$ with hydrogen-bonded methanol as electrophile, and $k_{MAP}[MeOH][AP]$ with hydrogen-bonding disrupted by the aprotic solvent.