• Journal of Pharmaceutical Investigation
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• v.29 no.3
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• pp.205-210
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• 1999

To formulate the parenteral delivery of a new cephalosporin derivative, 7-${\beta}$-[(2)-2-(2-arninothiazol-4-yl)-2methoxyiminoacetamido]- 3- [(2,3-cyclopenteno-4-carbamoyl-l-pyridinium)methyl]- 3-cephem-4-carboxylate sulfate( CKD604), the stability and solubility of CKD-604 in various aqueous media were investigated. The degradation kinetics of CKD-604 in aqueous solutions (ionic strength 0.1, pH 1-8) were studied at $37^{\circ}C$. The observed degradation rates followed pseudo first order kinetics. The pH-rate profile exhibited a minimum degradation rate at pH 5. The Arrhenius activation energy was 14.2 kcal/mol in pH 5 buffer solution. Excellent agreement between the cephalosporins' theoretical pH-rate profile and the experimental data indicated that the degradation pathway of CKD-604 could be predicted according to the general pathway of cephalosporins. The solubility of CKD-604 was 8.16 mg/ml at $25^{\circ}C$. To enhance the solubility and adjust the suitable pH, CKD-604 was solubilized by using sodium ascorbate, ascorbic acid and urea. The compositions were obtained to satisfy optimum pH and concentration, and the total amount of additives was several times of the active ingredient, CKD-604.

• Journal of Animal Science and Technology
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• v.46 no.2
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• pp.251-260
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• 2004

The feasibility and stability of ORP, pH(mV) and DO as a real-time control parameter for SBR process were evaluated in this study. During operation, NBP(nitrogen break point) and NKP(nitrate knee point), which reveal the biological and chemical changes of pollutants, were clearly observed on ORP and pH(mV)-time profiles, and those control points were easily detected by tracking the moving slope changes(MSC). However, when balance of aeration rate to loading rate, or to OUR(oxygen uptake rate), was not optimally maintained, either false NBP was occurred on ORP and DO curves before the appearance of real NBP or specific NBP feature was disappeared on ORP curve. Under that condition, however, very distinct NBP was found on pH(mV)-time profile, and stable detection of that point was feasible by tracking MSC. These results might mean that pH(mV) is superior real-time control parameter for aerobic process than ORP and DO. Meanwhile, as a real-time control parameter for anoxic process, ORP was very stable and more useful parameter than others. Based on these results, a stable real-time control of process can be achieved by using the ORP and pH(mv) parameters in combination rather than using separately. A complete removal of pollutants could be always ensured with this real-time control technology, despite the variations of wastewater and operation condition, as well as an optimization of treatment time and capacity could be feasible.

• Biomolecules & Therapeutics
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• v.1 no.1
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• pp.31-36
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• 1993

To evaluate the feasibility of transmucosal delivery of methionine enkephalin analog, [$D-Ala^2$]-me-thionine enkephalinamide (YAGFM), the influence of pH, temperature, ionic strength and initial peptide concentration on the physicochemical stability of YAGFM in aqueous buffered solutions were investigated using a stability-indicating HPLC method. The degradation of YAGFM followed the pseudo-first-order kinetics. From the pH-rate profile, the maximum stability of YAGFM was shown to be at the pH of about 5.0. The halflife for the degradation of YAGFM was found to be 181.3 days at pH 5.0 and $37^{\circ}C.$ Arrhenius plots of the data obtained at 25~$45^{\circ}C$ were reasonably linear with a correlation coefficient greater than 0.99, and the activation energy was calculated to be 8.9 kcal/mole. A higher ionic strength and/or a higher peptide concentration in buffered solutions retarded the degradation of YAGFM.

• Journal of Animal Science and Technology
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• v.50 no.4
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• pp.561-572
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• 2008

Responses of real-time control parameters, such as ORP, DO and pH, to the conditions of biological animal wastewater treatment process were examined to evaluate the stability of real-time control using each parameter. Also an optimum index for supplemental carbon source addition based on NOx-N level was determined under a consideration of denitrification rate by endogenous respiration of microorganism and residual organic matter in liquor. Experiment was performed with lab-scale sequencing batch reactor(SBR) and working volume of the process was 45L. The distinctive nitrogen break point(NBP) on ORP-and DO-time profiles, which mean the termination of nitrification, started disappearing with the maintenance of low NH4-N loading rate. Also the NBP on ORP-and DO-time profiles was no longer observed when high NOx-N was loaded into the reactor, and the sensitivity of ORP became dull with the increase of NOx-N level. However, the distinctive NBP was constantly occurred on pH(mV)-time profile, maintaining unique profile patterns. This stable occurrence of NBP on pH(mV)-time profile was lasted even at very high NOx-N:NH4-N ratio(over 80:1) in reactor, and the specific point could be easily detected by tracking moving slope change(MSC) of the curve. Revelation of NBP on pH(mV)-time profile and recognition of the realtime control point using MSC were stable at a condition of over 300mg/L NOx-N level in reactor. The occurrence of distinctive NBP was persistent on pH(mV)-time profile even at a level of 10,000mg/L STOC(soluble total organic carbon) and the recognition of NBP was feasible by tracing MSC, but that point on ORP and DO-time profiles began to disappear with the increase of STOC level in reactor. The denitrfication rate by endogenous respiration and residual organic matter was about 0.4mg/L.hr., and it was found that 0.83 would be accepted as an index for supplemental carbon source addition when 0.1 of safety factor was applied.

• Bulletin of the Korean Chemical Society
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• v.6 no.5
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• pp.280-284
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• 1985

Kinetic measurements of the 5-nitrofurfural-hydrazine reaction in various pH ranges of aquous solution were carried out by ultraviolet spectrophotometry at $25^{\circ},\;35^{\circ}\;and\;45^{\circ}C$. The observed rate of the reaction varies with the change in pH, which gives characteristic "bell-type" rate acidity profile. The maximum rate is shown in the vicinity of pH 4. This reaction procceds with rate-determining attack of hydrazine on the 5-nitrofurfural at low pH and undergoes a change in rate-determining step to dehydration of the addition intermediate as pH increases. The reaction has a "reactant-like transition state" which precedes intermediate in low pH and "product-like transition state" which follows it in neutral pH. The geometry of 5-nitrofurfural-hydrazine intermediate was estimated with PCILO method associated with CNDO/2 scheme.

• Bulletin of the Korean Chemical Society
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• v.18 no.4
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• pp.374-379
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• 1997

The rate constants for the nucleophilic addition of thiophenol derivatives (p-OCH3, H, p-CH3, m-CH3, p-Br and p-NO2) to 4'-[N-(9-acridinyl)]-1'-(N-methanesulfonyl)-3'-methoxyquinonediimide (AMQD) were determined by ultraviolet spectrophotometer in water at 5 ℃, and rate equations which can be applied over a wide pH range were obtained. On the basis of pH-rate profile, Bronsted plot, adduct analysis, general base catalysis and substituent effect, a plausible mechanism of this addition reaction was proposed: Below pH 2.5, the reaction proceeded by the addition of thiophenol molecule to 6'-position of quinonoid after protonation at the acridinyl nitrogen. Above pH 6.2, the addition of sulfide anion to 6'-position of quinonoid was rate controlling. However, in the range of pH 3.0-6.0, these two reactions occured competively.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.142-147
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• 2009

The recent H.264/AVC video coding standard provides a higher coding efficiency than previous standards. H.264/AVC achieves a bit rate saving of more than 50 % with many new technologies, but it is computationally complex. Most of fast mode decision algorithms have focused on Baseline profile of H.264/AVC. In this paper, a fast block mode decision scheme for P- slices in High profile is proposed to reduce the computational complexity for H.264/AVC because the High profile is useful for broadcasting and storage applications. To reduce the block mode decision complexity in P- pictures of High profile, we use the SAD value after $16{\times}16$ block motion estimation. This SAD value is used for the classification feature to divide all block modes into some proper candidate block modes. The proposed algorithm shows average speed-up factors of 47.42 ${\sim}$ 67.04% for IPPP sequences.

• Biomolecules & Therapeutics
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• v.8 no.4
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• pp.332-337
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• 2000

Physicochemical properties of aspalatone (acetylsalicylic acid maltol ester, AM), which has been recently found to have an antithrombotic effect, were studied in terms of solubility, dissolution, partition coefficient (Pc) and stability. The solubility of AM at 37$^{\circ}C$ was about 1.2 mg/ml and the P$_{c}$ value for n-octanol/water and chloroform/water was 11.4 and 382.6, respectively. Dissolution rates of AM at pH 1.2 and 6.8 were more than 80% within 30 min. The degradation of AM followed apparent first-order kinetics, and was dependent on temperature, pH and ionic strength. From the pH-rate profile, the optimal pH was found to be at around 4.0. Half-lives at pH 1.2 and 6.8 were 33.5 and 44.4 hr, respectively. The degradation rate of AM at pH 1.2 was somewhat faster than that of aspirin, but at pH 7.0, the degradation rate of AM was slower than that of aspirin.n.

• Bulletin of the Korean Chemical Society
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• v.24 no.3
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• pp.306-310
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• 2003

Hydrolysis reactions of S-phenyl-S-vinyl-N-p-tosylsulfilimine (VSI) and its derivatives at various pH have been investigated kinetically. The hydrolysis reactions produced phenylvinylsulfoxide and p-toluene sulfonamide as the products. The reactions are first order and Hammett ρ values for pH 1.0, 6.0, and 11.0 are 0.82, 0.45, and 0.57, respectively. This reaction is not catalyzed by general base. The plot of k vs pH shows that there are three different regions of the rate constants $(k_t)$ in the profile.; At pH < 2 and pH > 10, the rate constants are directly proportional to the concentrations of hydronium and hydroxide ion catalyzed reactions, respectively. The rate constant remains nearly the same at 2 < pH < 10. On the bases of these results, the plausible hydrolysis mechanism and a rate equation have been proposed: At pH < 2.0, the reaction proceeds via the addition of water molecule to sulfur after protonation at the nitrogen atom of the sulfilimine, whereas at pH > 10.0, the reaction proceeds by the addition of hydroxide ion to sulfur directly. In the range of pH 2.0-10.0, the addition of water to sulfur of sulfilimine appears to be the rate controlling step.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.1 s.16
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• pp.13-21
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• 2005

Experiments on settling behaviour of fine-grained particles without destroying the large fragile aggregates were carried out in still water with a CCD (Charged Coupled Device)-Camera. The experiments dealt with the measuring of the vertical concentration profile of cohesive particles with a CCD-Camera and the physico-chemical influences (NaCl, density, temperature and pH value) on the vertical distribution of the concentration. The vertical concentration profile of fine suspended particles (alumina and quartz) was possible up to $20,000\;mg/{\ell}$ with a CCD-Camera. The vertical concentration profile of cohesive sediments was on the decrease because of the increasing initial concentration, temperature and salinity. The vertical concentration profile of alumina was on the decrease quicker than quartz with increasing salinity. Furthermore, the pH value affects the settling behaviour of alumina. At a PH value of 4.2 the settling rate of the particles was very low and on the increase until pH 8.9 because of the aggregation behaviour of particles. From the PH value of 9 the average settling velocity was on the decrease.