A synthetic method for 2-arylpyrimidines by using oxidative dehydrosulfurative carbon-carbon cross-coupling reaction under a Pd/Cu catalytic system is described. This reaction protocol offers rapid access to various 2-arylpyrimidines in a single step from a wide range of the readily available 3,4-dihydropyrimidin-1H-2-thione (DHPM) and arylboronic acid coupling partners.

Leucine-responsive regulatory protein (Lrp) is a global regulatory protein of molecular weight 18.8 kDa and is widely known to regulate a lot of metabolic and functional activities of operons in enteric bacteria such as Escherichia coli. This research study was designed with the aim of elucidating information about the mechanism by which Lrp protein is able to regulate the expression. In order to achieve this, mutant and wild type plasmids inserting the genes code for Lrp F57W, Lrp F90W, Lrp F93W, Lrp R145W, and Lrp Wt proteins were generated by site-directed mutagenesis and polymerase chain reaction. The tryptophan containing mutant Lrps which have intrinsic fluorescence characteristics obtained from this research experiments will give an information into the three dimensional structure of Lrp F57W, Lrp F90W, Lrp F93W, and Lrp R145W such as the orientation of the tryptophan as well as the distance between the binding site and tryptophan in the mutant proteins.

This work demonstrates simulated potential-step experiments to obtain i-E curves of reversible and quasi-reversible electrochemical reactions at stationary and rotating electrodes. The i-E curves of a reversible reaction demonstrated the effect of rotation on the position and diffusion limiting current. At rotating electrode which permitted much faster mass transfer, specifically, the half wave potentials shifted by 4.7 mV in the positive direction, and the limiting currents were much enhanced. On the other hand, an experimental procedure to determine the standard charge transfer rate constant of a quasi-reversible reaction using rotating electrode was demonstrated also. In such simulation experiments, adjustment of various parameters was suggested to understand the ways to modify the i-E curves. Such simulation experiments certainly have some advantages over real experiments in terms of cost, time and so on.

충남대학교에서 사용하는 일반화학 교재(줌달 등 공저)에 나오는 두 가지 오류에 관하여 논의하였다. 하나는 물의 상평형도와 관련된 내용으로, 얼음에 가해지는 압력이 체중에 의해 높아져 물이 녹고, 그 결과 얼음 표면의 마찰이 줄어들어 스케이트를 탈 수 있다는 논의이다. 이 논의는 정량적 검토 없이 이루어진 것으로 올바르지 않다. 또 다른 오류는 평형 상수에 관한 논의로, 교재에는 주어진 반응에 대하여 이상 기체 방정식으로 연결되는 두 가지 평형 상수가 나온다. 이는 주어진 반응의 반응 깁스 에너지는 하나뿐이라는 사실과 상충된다.

Two errors of the general chemistry textbook, Chemistry by Zumdahl et al., used in Chungnam National University are discussed. One is related to the phase diagram of water. In the textbook, it is discussed that ice skating is possible by melting of ice due to the pressure rise by the body weight, which is incorrect conclusion without quantitative consideration. Two different equilibrium constants related through the equation of ideal gas appear for a given reaction in the textbook, which contradicts that there is only one Gibbs energy of reaction for a given reaction.

In an effort to search for novel quaternary bismuth sulfide compounds, we have explored K/Ag/Bi/S system and encountered novel quaternary bismuth sulfide compound, KAgBi2S4 using K2Sx molten salt at intermediate temperature. The black hexagonal crystals of KAgBi2S4 are obtained at 350℃ and crystallized in the space group P63/mmc (no.194) with a=4.0216(3)Å, c=30.066(3)Å, γ=120°, Final R1/wR2=4.37/13.15%. The structure of KAgBi2S4 is composed of negatively charged [M3S4]n n- layers separated by charge balancing K+ ions which are loosely packed in the interlayer spaces.

Exosomes were isolated from human saliva using ExoQuick, PEG 8,000, and PEG 10,000, and the degree of exosome enrichment was confirmed using size exclusion chromatography (SEC). All of the three enrichment methods showed enrichment of exosomes based on the comparison of SEC chromatograms, where the ExoQuick method demonstrated the most efficient enrichment followed by PEG 10,000 and PEG 8,000.

Copper and aluminum are high conductivity materials and relatively easy to obtain than silver or gold, which are also known as good-electric materials. Because of these characteristics, copper and aluminum are used for metallization in semiconductor fabrication process. In order to identify these physical properties, thin films of copper and aluminum were fabricated by a vacuum deposition method. We measured the resistivity in the temperature range of 80-500 K using a Hall effect measurement system. The crystalline orientations were identified by using a X-ray diffraction method. The surface morphology and composition of the thin films were investigated through scanning electron microscopy and energy dispersive spectrometry.

In this study, we briefly review the basic concepts of band theory in solid-state systems. We take the two-dimensional graphene as a reference system and apply one-orbital tight binding model in order to compute the electronic structure of graphene. We compare the tight binding model with density functional theory calculations and find that the two methods are in good agreement.

Kagome lattice materials of AV3Sb5 (A= K, Rb, Cs) have exotic physical properties such as charge density wave (CDW), superconductivity, and anomalous Hall effect. Since previous AV3Sb5 studies have been mainly focused on the three-dimensional bulk system, in this study we investigate the low-dimensional AV3Sb5 system within density functional theory (DFT). From the DFT calculations, we found that the two-dimensional monolayer Kagome lattice materials of AV3Sb5 also show the similar CDW states as observed in the bulk system. Moreover, the CDW phases in the two-dimensional system have more stable than those in the three-dimensional system. It indicates that the lowering dimensionality makes the Kagome lattice materials more stable and it is able to tune the system into one with desired physical properties.

Density functional theory (DFT) is an essential tool for computing the electronic structure of atoms, molecules, and solid-state materials. In this paper, we briefly review the current status of DFT including some basic explanation of many-body Hamiltonian, Born-Oppenheimer approximation, Hohenberg-Kohn theorem, and Kohn-Sham equation. The last two concepts, Hohenberg-Kohn theorem and Kohn-Sham equation, are the most important ones of DFT, hence we summarize the two ones intensively in this review.