• Archives of Pharmacal Research
• /
• v.28 no.3
• /
• pp.370-375
• /
• 2005

The objective of this study was to develop a new reverse micelle-based microencapsulation technique to load tetracycline hydrochloride into PLGA microspheres. To do so, a reverse micellar system was formulated to dissolve tetracycline hydrochloride and water in ethyl formate with the aid of cetyltrimethylammonium bromide. The resultant micellar solution was used to dissolve 0.3 to 0.75 g of PLGA, and microspheres were prepared following a modified solvent quenching technique. As a control experiment, the drug was encapsulated into PLGA microspheres via a conventional methylene chloride-based emulsion procedure. The micro­spheres were then characterized with regard to drug loading efficiency, their size distribution and morphology. The reverse micellar procedure led to the formation of free-flowing, spherical microspheres with the size mode of 88 ~m. When PLGA microspheres were prepared follow­ing the conventional methylene chloride-based procedure, most of tetracycline hydrochloride leached to the aqueous external phase: A maximal loading efficiency observed our experimental conditions was below $5\%$. Their surfaces had numerous pores, while their internal architecture was honey-combed. In sharp contrast, the new reverse micellar encapsulation technique permitted the attainment of a maximal loading efficiency of 63.19 $\pm$$0.64\%$. Also, the microspheres had smooth and pore-free surfaces, and hollow cavities were absent from their internal matrices. The results of this study demonstrated that PLGA microspheres could be successfully prepared following the new reverse micellar encapsulation technique.

• Korean Journal of Applied Biomechanics
• /
• v.22 no.3
• /
• pp.305-314
• /
• 2012

The purpose of this study was to investigate the effects of joint kinetics and coordination on within-individual differences in maximum vertical jump. 10 male subjects aged 20 to 30 performed six trials in maximum vertical jump and with based on jump height the good(GP) and bad(BP) performances for each subject were compared on joint kinetics of lower extremity and coordination parameters such as joint reverse and relative phase. The results showed that maximum moment, power, and work done of hip joint and maximum moment of ankle joint in GP were significantly higher than that in the BP but no significant differences for the knee joint. We could observe a significant difference in joint reverse timing between both conditions. And also the relative phase on ankle-knee and ankle-hip in GP were significantly lower than that in the BP, which means that in GP joint movements were more in-phase synchronized mode. In conclusion, mechanical outputs of hip and ankle joints had an effect on within-individual differences in vertical jump and the inter-joint coordination and coordination including sequence and timing of joint motion also might be high influential factors on the performances within individual.

• Proceeding of EDISON Challenge
• /
• 2015.03a
• /
• pp.151-155
• /
• 2015

The molecular interactions between the nucleic acid bases and water molecules are important in organism. Despite Adenine-Thymine Hoogsteen base pair and Guanine-Cytosine Watson-Crick base pair have been demonstrated to be most stable in a gas phase, the effect of water on the stability of these base pairs remains elusive. Here we report the structural and thermodynamic characteristics on possible Adenine-Thymine and Guanine-Cytosine base pairs in a gas phase as well as in an aqueous phase by using quantum mechanical method and statistical mechanical calculations. First, we optimized the direct base-pair interaction energies of four Adenine-Thymine base pairs (Hoogsteen base pair, reverse Hoogsteen base pair, Watson-Crick base pair, and reverse Watson-Crick base pair) and three Guanine-Cytosine base pairs (GC1 base pair, GC2 base pair, and Watson Crick base pair) in a gas phase at the $B3LYP/6-31+G^{**}$ level. Then, the effect of solvent was quantified by the electronic reorganization energy and the solvation free energy by statistical mechanical calculations. Thereby, we discuss the effect of water on the stability of Adenine-Thymine and Guanine-Cytosine base pairs, and argue why Adenine-Thymine Watson-Crick base pair and Guanine-Cytosine Watson-Crick base pair are most stable in an aqueous environment.

• KSBB Journal
• /
• v.16 no.1
• /
• pp.48-53
• /
• 2001

Bovine serum albumin(BSA) was solubilized into the reverse micellar phase consisting of sodium bis(2-ethylhexyl) sulfosuccinate(AOT) and isooctane using the phase transfer method. Of particular interest in this study were the effects of pH and the added salt type and concentration on the solubilization efficiency. When univalent or divalent salts such as KCl, NaCl, $MgCl_2$, or $CaCl_2$ were added to the aqueous phase at a concentration of 0.1 M, maximum solubilization efficiency was attained at a pH ranging from 5 to 7, depending on the added salt type. Increased salt concentration up to 1 M resulted in an increased solubilization efficiency for $CaCl_2$ and NaCl, while the addition of $MgCl_2$ beyond 0.1 M showed an anomalous trend. Further, it was noteworthy that too a large extent the protein precipitated in the interface between the organic and aqueous phases at lower pHs and lower salt concentrations. The size of the reverse micelle water pool was estimated by measuring the molar ratio of the surfactant to the water, $W_0$. Irrespective of pH in the aqueous phase, the resulting value of $W_0$ was almost constant, eg., 20 for $MgCl_2$ . However, the value of $W_0$ decreased with increased salt concentration in the cases of KCl and $CaCl_2$.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2004.11a
• /
• pp.233-235
• /
• 2004

This paper studies protective coordination of utility interconnected multiple distirbuted generations(DG). The study of protective coordination interconnected DG has been conducted. A protective coordination of utility disturbed by reverse current of DG. Therefore, A protetive device is not operate when reverse current flows. In this paper, we use phase difference between V and I. Also, we studied protective coordination algorithm of utility interconnected multiple DG.

• Journal of Electrical Engineering and information Science
• /
• v.2 no.3
• /
• pp.66-70
• /
• 1997

The steam generator level is susceptible to the nonminimum phase in dynamics due to the thermal reverse effects known as "shrink and swell" in a pressurized water reactor. A state feedback assisted control concept is presented for the change of dynamic performance to the minimum phase the concept incorporates a nonlinear digital observer as a part of the control system. The observer is deviced to estimate the state variables that provide the true indication of water inventory by compensating for shrink and swell effects. The concept is validated with implementation into the steam generator simulation model.

• Journal of Pharmaceutical Investigation
• /
• v.26 no.2
• /
• pp.83-89
• /
• 1996

A reverse-phase HPLC method to determine DL-Carnitine Hydrochloride in pharmaceutical preparation is described. UV absorption derivatives of DL-Carnitine Hydrochloride were formed with p-Bromophenacyl Bromide in an essentially quantitative manner using crown ether as catalyst. The DL-Carnitine-bromophenacyl ester absorbed UV radiation strongly at 254nm, allowing the detection of as small a quantity as 12.5ng of DL-Carnitine Hydrochloride. A linear defection range was $5\;{\times}\;10-8 \;{\sim}\;5\;{\times}\;10-7M$ of DL-Carnitine Hydrochloride. And the linear regression at various drug concentration was =0.999 (n=10). The DL-Carnitine Hydrochloride in pharmaceutical preparation was successfully derivatized and separated from other constituents by reverse phase HPLC with detection at 254 nm.

• Journal of Microbiology and Biotechnology
• /
• v.10 no.2
• /
• pp.233-237
• /
• 2000

As part of a continuing investigation to identify free radical scavengers from the fruit bodies of basidiomycetes, we isolated two p-terphenyl compounds, designated as PAl and PA2l, from cethanolic extract of the fruit body of Pasillus panuoides. The methanolic extract was processed by ethyl acetate extraction and silica gel column chromatography to yield two active fraction. PAl was obtained from one of the fractions through Sephadex LH-20 and silica gel column chromatographies and reverse-phase HPLC. The other fraction was purified by Sephadex LH-20 and reverse-phase column chromatographies to produce PA2. The compounds PA1 and PA2 were identified as leucomentin-4 and leucomentin-2, respectively, on the basis of various spectroscopic analyses. These compounds exhibited strong inhibitory activities against lipid peroxidation in rat liver microsomes with IC_{50}$ values of 0.10 and $0.06{\;}\mu\textrm{g}ml$, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.6A
• /
• pp.845-854
• /
• 1999

In the reverse link of DS/CDMA systems, the Peak-to-Average Ratio(PAR) performance can be analyzed by phase variations of spread signals. In the paper, we propose s PAR analysis method using phase variations of signals. Using this method, we analyze the PAR performances of existing spreading methods and suggest several methods improving the PAR performances. Also we show the proposed methods have negligible BER degradation compared to the existing ones.

• Journal of Applied Biological Chemistry
• /
• v.55 no.1
• /
• pp.61-65
• /
• 2012

Three major curcuminoids in turmeric (Curcuma longa), curcumin, demethoxycurcumin, and bisdemethoxycurcumin, were efficiently extracted by optimizing extraction condition and simultaneously analyzed and identified using reverse phase high-performance liquid chromatography, thin-layer chromatography, and liquid chromatography-mass spectrometry method. The highest yield of extraction amount 0.279 g, 9.30% was obtained by dipping method with extraction time of 7 h.