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Bay Van Tran,Son Ich Ngo,임영일,고강석,노남선 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.2
The bubble breakage rate in gas-liquid bubble columns increases for organic liquid and at high pressure. This study developed a breakage model that accounts for different liquid properties in gas-liquid pressurized bubble columns in the homogeneous regime. The Luo (1996), Lehr (2002), and Wang (2003) breakage models, which are widely used for the population balance equation (PBE) of bubble columns, were compared in terms of the total breakage rate, daughter size distribution, and computational time. The model with two empirical equations, modified from Luo’s breakage kernel, was proposed. One represented bubble deformation behavior in different liquid properties in terms of buoyancy, surface tension, and viscosity. The other considered the effect of operating pressure (or gas density) on the breakage rate. The modified model was compared with experimental data and a rigorous breakage model from the literature. The proposed breakage model shows good agreement with experimental data and computational efficiency. This breakage model is applicable for computational fluid dynamics with PBE in pressurized bubble columns with organic liquids.
EXPONENTIAL STABILITY OF A CLASS OF NONLINEAR DIFFERENCE EQUATIONS IN BANACH SPACES
Nguyen, Sinh Bay,Le, Van Hien,Hieu, Trinh Korean Mathematical Society 2017 대한수학회논문집 Vol.32 No.4
The problems of global and local exponential stability analysis of a class of nonlinear non-autonomous difference equations in Banach spaces are studied in this paper. By a novel comparison technique, new explicit exponential stability conditions are derived. Numerical examples are given to illustrate the effectiveness of the obtained results.
Hien, Nguyen Khoa,Nhan, Doan Thanh,Kim, Won Young,Van Bay, Mai,Nam, Pham Cam,Van, Dang Ung,Lim, In-Taek,Kim, Jong Seung,Quang, Duong Tuan Elsevier 2018 Dyes and pigments Vol.152 No.-
<P><B>Abstract</B></P> <P>A coumarin-based fluorescent sensor (7-Acryloxy-4-methylcoumarin, <B>AMC</B>) for biothiols has been studied by a combination of quantum chemical calculation and experimental investigation. The <B>AMC</B> selectively reacts with mercapto biomolecules via Michael addition, which can be served as a ratiometric fluorescent sensor for thiol-containing biomolecules. The <B>AMC</B> sensor shows a selectivity towards biothiols with sensitivity in the order of cysteine > glutathione > homocysteine. Moreover, the <B>AMC</B> sensor can detect the cysteine concentration within the intracellular level. The results of the theoretical investigations on the electron excited states show that the lack of overlapping between MOs in transitions of the lower-lying singlet electron excited states and the small energy gap between electron excited states are the cause of fluorescence from the higher-lying singlet electron excited states, as an exception from Kasha's rule. The fluorescence from the higher-lying singlet electron excited states leads to marked fluorescence enhancement at long wavelength in the products of addition reaction of biothiols to <B>AMC</B> sensor.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A coumarin-derived ratiometric fluorescent sensor for the determination of biothiols via Michael addition was synthesized. </LI> <LI> Absorption and fluorescence characteristics were clarified on the basis of electronically excited states optimized geometries. </LI> <LI> The lack of overlap between MOs, and the small energy gap between electronically excited states lead to an exception of Kasha's rule. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>