• Journal of the Korean Chemical Society
• /
• v.36 no.6
• /
• pp.919-924
• /
• 1992

The kinetics of the hydrolysis of N-benzylidenebenzenesulfonamide derivatives have been investigated by ultraviolet spectrophotometry in $H_2O$ at $25^{\circ}C$. A rate equation which can be applied over a wide pH range was obtained. The substituent effect on the hydrolysis of N-benzylidenebenzenesulfonamide derivatives were studied and rate of hydrolysis is known to be accelerated by electron withdrowing group. Final product of the hydrolysis was benzenesulfonamide and benzaldehyde. Base on the rate equation, substituent effect, general base effect and final products, hydrolysis of N-benzylidenebenzenesulfonamide derivatives seemed to be initiated by the hydronium ion at the pH 0.2${\sim}$2.5 and proceeded by the neutral $H_2O$ molecule at pH 3.0${\sim}$8.0 but proceeded by the hydroxide ion at above pH 8.5.

• Journal of the Korean Magnetics Society
• /
• v.5 no.3
• /
• pp.210-215
• /
• 1995

$Glass\Cr_{40\AA}\{[Cr_{10\AA}\NiFe_{50\AA}]}_N$ multilayers (number of layer N = 1, 2, 3, 4, 5, 6, 10) were made by dc magnetron sputtering under magnetic anisotropy of 200 G. Magnetoresistance curve MR(xx), MR(xy) were measured for the parallel and perpendicular current direction to external magnetic field. MR(xx) curves for the number of layer N=1, 5, 10 were almost became about zero percent, however the curves of other numbers appeared the phenomena of "positive magnetoresistance" that the resistance increased to external magnetic field, and the irregular and reversed curves in the vicinity of H=0 Oe.

• Environmental Engineering Research
• /
• v.23 no.2
• /
• pp.216-222
• /
• 2018

The growth characteristics of Spirulina platensis were investigated using four photo-bioreactors with $CO_2$-mixed air flows. Each reactor was operated under a specific condition: 3% $CO_2$ at 50 mL/min, 3% $CO_2$ at 150 mL/min, 6% $CO_2$ at 50 mL/min, and 6% CO2 at 150 mL/min. The 3% $CO_2$ at 150 mL/min condition produced the highest algal growth rate, while the 6% $CO_2$ at 150 mL/min conditioned produced the lowest. The algal growth performance was suitably assessed by the linear growth curve rather than the exponential growth. The medium pH decreased from 9.5 to 8.7-8.8 (3% $CO_2$) and 8.4-8.5 (6% $CO_2$), of which trends were predicted only by the pH-carbonate equilibrium and the reaction kinetics between dissolved $CO_2$ and $HCO_3{^-}$. Based on the stoichiometry between the nutrient amounts and cell elements, it was predicted that depleted nitrogen (N) at the early stage of the cultivation would reduce the algal growth rates due to nutrient starvation. In this study, use of the photobioreactors capable of good light energy distribution, proper ranges of $CO_2$ in bubbles and medium pH facilitated production of high amounts of algal biomass despite N limitation.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.4
• /
• pp.557-559
• /
• 2004

The aminolyses of anilinothioethers $(C_6H_5N(CH_3)CH_2SC_6H_4Z)$ in acetonitrile with benzylamines $(XC_6H_4CH_2NH_2)$ have been investigated. The rates are much lower in acetonitrile than in methanol (with aniline). The Bronsted ${\beta}_X$ values are similar but ${\beta}_Z$ values are smaller compared to those for the reactions in MeOH with anilines. The large negative ${\rho}_{XZ}({\cong}-0.8$, after correction for fall-off) value is interpreted to indicate a frontside attack $S_N2$ mechanism, in which the two oppositely changed reaction centers in the TS, $-N^{{\delta}+}{\cdots}S^{{\delta}-}-$, are in close vicinity increasing the interaction between nucleophile and leaving group. The inverse secondary kinetic isotope effects ($k_H/k_D$ < 1.0) are observed with deuterated benzylamines $(XC_6H_4CH_2ND_2)$.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.4 no.1
• /
• pp.17-20
• /
• 1999

Facile synthetic methods of 2',5'-dideoxy-, 2',3'-dideoxy- and 3'-deoxy-1, N6-ethenoadenosine nucleosides by either an enzymatic dideoxyribosyl transfer reaction or a simple chemical reaction were proposed. The synthesis products were isolated and purified by preparative HPLC and their structures were confirmed by 1H NMR (500 MHz) and FAB-MS including high resolution mass measurement. These modified nucleoside analogs have not been reported yet. Therefore, these modified nucleoside analogs are of potential value to be studied further for biological activity such as anticancer or antiviral.

• Korean Journal of Crystallography
• /
• v.10 no.2
• /
• pp.125-129
• /
• 1999

X-선 회절법을 이용하여 1-(3 Carbamoyl-3,3-diphenylpropyl)-1-methylhexahydro-1H-azepinium iodide[이하: DIP]의 분자 및 결정구조를 규명하였다. 이 결정의 분자식은 C23H31N2O·I, 결정계는 Monoclinic이며 공간군은 P21이다. 단위포 상수는 a =8.937(1) Å, b=19.522(2) Å, c=6.485(2) Å이며, β= 105.18(2)°, V=1091.9(6) Å3, T=293(2)K, Z=2, Dc=1.45 Mgm-3이다. 회절반점들의 세기는 Enarf-Nonius CAD-4 diffractometer로 얻었으며 Mo Katjs(λ=0.71073 Å)을 사용하였다. 분자구조는 직접법으로 개략적인 분자모델을 설정하고, Fo>4σ(Fo)인 4112개의 독립 회절 데이터에 대하여 최소자승법으로 정밀화하여 최종 신뢰도 값 R=5.23%인 최종적인 분자모형을 구하였다.

• Analytical Science and Technology
• /
• v.6 no.5
• /
• pp.501-508
• /
• 1993

In n/${\gamma}$ mixed field of $^{241}Am-Be$(${\alpha}$, n) neutron source, we seperated the neutron component from gamma ray component. At the center of the detector, $^6Li$ was doped on the cerium activated glass plate for $^6Li$(${\alpha}$, n)T nuclear reaction. The time differences of the light following excitations by different scintillators, BC501($C_8H_{10}$) and cerium, and by the same scintillator for different radiations as neutrons and gamma-rays are used to apply the methods of PSD(Pulse Shape Discriminator) and CFD(Constant Fraction Discriminator). The figure of merit of $^6Li$ fast neutron spectrometer is estimated as 1.36.

• Korean Journal of Crystallography
• /
• v.4 no.2
• /
• pp.86-91
• /
• 1993

C5H6N3O2+ H2Po4-, Mr=2 2 1. 6 9 3, Orthorhombic, Pna21, a=25.680(3)A, b=6.234(1)A, V=908.23A3, Z=4, Dx=1.734Mgm-3, λ(MoKa)=0.7169A, μ=2.60-1mm F(000)488, T=297K, final R=0.0328 for 881 independent reflection. The crystal contains parallel to the b-c Plance(the cleavage plane) and stacks of 2-amino-5 -nitropryridinium (2A5NP+) ions connecting the phosphate planes.

• Journal of the Korean Magnetic Resonance Society
• /
• v.20 no.1
• /
• pp.1-6
• /
• 2016

The proton NMR line widths and spin-lattice relaxation rates, $T_1^{-1}$, of ferroelectric $LiH_3(SeO_3)_2$, $Li_2SO_4{\cdot}H_2O$, and $LiN_2H_5SO_4$ single crystals were measured as a function of temperature. The line width measurements reveal rigid lattice behavior of all the crystals at low temperatures and line narrowing due to molecular motion at higher temperatures. The temperature dependences of the proton $T_1^{-1}$ for these crystals exhibit maxima, which are attributed to the effects of molecular motion by the Bloembergen - Purcell - Pound theory. The activation energies for the molecular motions of $^1H$ in these crystals were obtained. From these analysis, $^1H$ in $LiH_3(SeO_3)_2$ undergoes molecular motion more easily than $^1H$ in $LiN_2H_5SO_4$ and $Li_2SO_4{\cdot}H_2O$ crystals.

• Bulletin of the Korean Chemical Society
• /
• v.20 no.1
• /
• pp.65-68
• /
• 1999

Novel mononuclear group 13 metal complexes with the formula (R2M){NC5H4C(CH3)NNC(S)NH(C6H5)} (M=Al, R=iC4H9 (1); M=Ga, R=iC4H9 (2); M=Al, R=CH2SiMe3 (3); M=Ga, R=CH2SiMe3 (4)) result when 2-acetyl pyridine 4-phenyl-thiosemicarbazone ligand is mixed with trialkyl aluminum or trialkylgallium. These compounds 1-4 are characterized by microanalysis, NMR (1H, 13C) spectroscopy, mass spectra, and singlecrystal X-ray diffraction. X-ray single-crystal diffraction analysis reveals that 1 is mononuclear metal compound with coordination number of 5 and N, N, S-coordination mode.