• Analytical Science and Technology
• /
• v.6 no.1
• /
• pp.29-37
• /
• 1993

Some new podands containing phenyl(B), benzyl(Bz), pyridine(Py), quinoline(Q) and naphthalene(Np) as end-groups, and oxygen(O) and sulfur(S) in ether chains as donor atoms have been synthesized. The univalent cation binding characteristics of these podands have been studied by NMR titration and solvent extraction. By NMR titration we have found that the most of podands form 1:1 complexes with $Ag^+$ ion. Especially, the substituted sulfur atoms in ether chains show the effects to enhance the stabilities. We also carried out the extractions of univalent cation picrates including alkaline metal, $Ag^+$, $Tl^+$ and $NH_4{^-}$ ions from aqueous to chloroform layer by using these podands. We found that the extractabilities of $Ag^+$ ion with the quinoline-containing podands such as, $Q_2O_4$, $Q_2O_5$ and $BQO_5$ were 86.8, 86.6 and 48.0% respectively, but the naphthalene-containing podands such as, $Np_2O_4$ and $Np_2O_5$ extracted quite small amount. Otherwise, in cases of $Bz_2O_3S_2$(89.4%), $B_2O_2S_2$(96.8%), $B_2O_3S_2$(58.9%), $Py_2O_2S_2$(58.8%), $Py_2O_3S_2$(42.1%), and $B_2O_4S$(15.0%), interestingly, $Bz_2O_3S_2$ which have sulfur atoms and benzyl groups showed the highest extraction selectivity for $Ag^+$ ion. This result seems due to not only the strong interaction of $Ag^+$ ion with sulfur donors according to the HSAB theory, but also the effective ${\pi}-{\pi}$ stacking interaction between two aromatic end-groups which is enhanced by the flexible methylene spacing group in benzyl groups instead of phenyl groups. The extraction coefficients gave the similar tendency as the extractabilities and the stabilities. From these results, it could be concluded that the predominant factor affected to extraction coefficients is the stabilities, which are strongly influenced by the structures of podands.

• Journal of Animal Science and Technology
• /
• v.48 no.5
• /
• pp.699-708
• /
• 2006

Ground rice, barley and corn were fed separately to the ruminally cannulated Hanwoo (Korean native cattle) for comparing their in situ and in vitro degradabilities, microbial growth, pH and gas production. It has been found that nearly all the dry matter (DM) and organic matter (OM) in barley and rice disappeared during 24 hr suspension in the rumen, but those in corn were only reduced by around 67%. Water soluble DM and OM fractions(‘a’), ranked from highest to lowest was corn, then rice and finally barley, but the order was reversed for content ‘b’, degradable fraction during time ‘t’. Judging by the degradation parameter of ‘b’ fraction, degradation rates per hour of DM and OM for barley were 38.3% and 37.2% respectively, significantly higher than those for rice (7.7% and 5.6%) and corn (4.1% and 1.3%). In general, results obtained from in vitro degradability of DM and OM were lower than those from in situ trials, but the ranking order of degradability was in agreement between both trials. In particular, ground rice has relatively lower in vitro microbial growth than corn or barley, but exhibited higher gas production. In addition, in vitro microbial growth of ground rice increased with up to 12 hr of incubation period, thereafter experienced a decrease with extended incubation time. pH of in vitro solution of rice decreased following 9 hr of incubation but gas production increased rapidly during the same period. From the results of DM and OM degradabilities and pH changes of in vitro solution with incubation time, it is concluded that rice represents a good source of energy for stability of rumen fermentation.

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

• Journal of Hospice and Palliative Care
• /
• v.18 no.4
• /
• pp.294-305
• /
• 2015

Purpose: The purpose of this study is to provide baseline data for the development of an educational program for hospice care for college students. Methods: A survey was conducted at three universities in B city with 143 students from September 5, 2014 through September 26, 2014. The data were analyzed by the SPSS 18 program. This study was approved by IRB. Results: The college students' spiritual well-being was at a medium level. Their attitudes to death were neutral, and perception of hospice care was at a medium level. Most of the participants (93.0%) had no training in hospice care. The participants' awareness of the purpose of hospice care was at a relatively high level. Their awareness of the need for hospice care was at a moderate level. The participants' spiritual well-being and their attitudes to death showed a weak but positive correlation (r=0.179, P=0.030). The relationship between their spiritual well-being and awareness of hospice care were positively correlated (r=0.203, P=0.015). Conclusion: The participants' perception of hospice care was low. Most of them had no experience of hospice care education. Also, the higher the spiritual stability was, the higher the participants' perception of the purpose and the necessity of hospice care was. And their perception of the hospice care varied depending on their family relationship, satisfaction with school life, and cognition of hospice care. Therefore, we need consider these variables to develop a hospice education program to enhance college students' attitudes to death and their perception of hospice care.

• Food Science of Animal Resources
• /
• v.26 no.2
• /
• pp.166-174
• /
• 2006

To determine the proper processing and storage conditions, physico-chemical, microbial and sensory properties of venison jerky under different dry times were measured during storage at $30^{\circ}C$ for 28 days. Samples were dried for 3 hr (T1), 4 hr (T2) and 5 hr (T3) at $75^{\circ}C$ in the smoke chamber, respectively. The pH of T1 was slightly lower than those of T2 and T3 as storage time increased. As dry and storage time increased, TBARS of T2 and T3 were significantly higher (p<0.05) than that of T1. In meat color, $L^*$ values of T3 showed slightly higher than those of T1 and T2, while at values were not clearly tendency by the passage of storage time. $b^*$ values of T2 and T3 were higher than that of T1. The water activity were significantly lower (p<0.05) in ,the order of T3$log_{10}$ CFU/g until 28 days and its number were accepted by sensory evaluation. In conclusions, T2 and T3 showed slightly high overall acceptability and lipid oxidative stability compared to T1 conditions. These results indicated that longer dry time ($4{\sim}5 hr$) of venison jerky would be better characteristics as compared to shorter dry time (3 hr) with increased storage time at $30^{\circ}C$.

• Journal of Life Science
• /
• v.25 no.5
• /
• pp.487-495
• /
• 2015

We carried out pH stability, chemical inhibition, chemical modification, and pH-dependent kinetic parameter assessments to further characterize protocatechuate 3,4-dioxygenase from Pseudomonas pseudoalcaligenes KF707. Protocatechuate 3,4-dioxygenase was stable in the pH range of 4.5~10.5. L-ascorbate and glutathione were competitive inhibitors with $K_{is}$ values of 0.17 mM and 0.86 mM, respectively. DL-dithiothreitol was a noncompetitive inhibitor with a $K_{is}$ value of 1.57 mM and a $K_{ii}$ value of 8.08 mM. Potassium cyanide, p-hydroxybenzoate, and sodium azide showed a noncompetitive inhibition pattern with $K_{is}$ values of 55.7 mM, 0.22 mM, and 15.64 mM, and $K_{ii}$ values of 94.1 mM, 8.08 mM, and 662.64 mM, respectively. $FeCl_{2}$ was the best competitive inhibitor with a $K_{is}$ value of $29{\mu}M$. $FeCl_{3}$, $MnCl_{2}$, $CoCl_{2}$, and $AlCl_{3}$ were also competitive inhibitors with $K_{is}$ values of 1.21 mM, 0.85 mM, 3.98 mM, and 0.21 mM, respectively. Other metal ions showed noncompetitive inhibition patterns. The pH-dependent kinetic parameter data showed that there may be at least two catalytic groups with pK values of 6.2 and 9.4 and two binding groups with pK values of 5.5 and 9.0. Lysine, cysteine, tyrosine, carboxyl, and histidine were modified by their own specific chemical modifiers, indicating that they are involved in substrate binding and catalysis.

• Journal of Life Science
• /
• v.25 no.5
• /
• pp.496-506
• /
• 2015

This study explored adequate water temperature ranges for maintaining stable water quality in a biofloc- based zero-water exchange culture system. Five experimental tanks with the following temperatures were set up: 10℃, 15℃, 20℃, 25℃, and 30℃. First, a biofloc-based culture system was developed in the experimental tanks; then, the tanks were stocked with goldfish and went without a water exchange for 60 days. Conditions for developing a biofloc-based culture system and stable water quality in low concentrations of inorganic nitrogen compounds at 10℃, 15℃, 20℃, 25℃, and 30℃ were maintained after 17, 26, 43, 68, and 78 days, respectively. Beginning from when the goldfish were stocked in the biofloc-based culture tanks, concentrations of $NH_4{^+}-N$ remained constant and at low levels at 10℃ and 15℃, but they showed a gradual increase at 20℃, 25℃, and 30℃. Concentrations of $NO_2{^-}-N$ and $NO_3{^-}-N$ at 10℃ and 15℃ did not remain at low levels and immediately increased. While $NO_2{^-}-N$ concentrations at above 20℃ remained constant and stable at relatively low levels, $NO_3{^-}-N$ concentrations showed a gradual increase. Conditions of 15℃ and below could not maintain low and stable concentrations of $NO_2{^-}-N$. In the pH range of 4.0 to 6.0, $NH_4{^+}-N$ concentration decreased as the pH rose. However, there was no correlation between pH and $NH_4{^+}-N$ concentration in the pH range of 6.0 to 8.0. These results indicate that pH levels should be kept at pH 6.0 and above to maintain a low and stable concentration of $NH_4{^+}-N$ at above 20℃.

• Journal of Life Science
• /
• v.27 no.2
• /
• pp.139-148
• /
• 2017

The inhibition of tyrosinase, a key enzyme in mammalian melanin synthesis, plays an important role in preventing skin pigmentation and melanoma. Therefore, tyrosinase inhibitors are very important in the fields of medicine and cosmetics. However, only a few tyrosinase inhibitors are currently available because of their toxic effects on skin or lack of selectivity and stability. Therefore, we synthesized a novel series of (E)-2-(substituted benzylidene)-2,3-dihydro-1H-cyclopenta[a]naphthalen-1-one derivatives and evaluated their inhibitory effects on mushroom tyrosinase, with the aim of discovering a novel tyrosinase inhibitor. Among 19 derivatives, MHY3655 ($IC_{50}=0.1456{\mu}M$) showed the strongest inhibitory effect on tyrosinase activity compared to kojic acid ($IC_{50}=17.2{\mu}M$), a well-known tyrosinase inhibitor. In addition, MHY3655 showed competitive inhibition on Lineweaver-Burk plots. We confirmed that MHY3655 strongly interacts with mushroom tyrosinase residues through the docking simulation. Substitutions with a hydroxy group at both R2 and R4 in the phenyl ring indicated that these groups play a major role in the high binding affinity to tyrosinase. Further, MHY3655 did not show cytotoxicity at the concentrations tested in B16F10 melanoma cells. In conclusion, the novel compound MHY3655 potentially shows tyrosinase inhibitory activity, and it could be used as an ingredient in whitening cosmetics.

• Journal of Life Science
• /
• v.27 no.7
• /
• pp.805-811
• /
• 2017

In the previous paper, we isolated a bacterium that can hydrolyze various organic materials from soybean paste, including cellulose, lipids, starch, and protein. The activity and chemical properties of the crude enzymes produced by the isolate Bacillus subtilis CK-2 were further investigated. Cellulase showed the highest activity at pH 5.0 and $55^{\circ}C$. The stability of cellulase was maintained within the ranges of pH 5.0~10.0 and $20{\sim}50^{\circ}C$. Cellulolytic enzymes were activated by a $Co^{2+}$ ion, demonstrating the highest activity at a 0.45%(w/v) concentration of $Co^{2+}$. The optimal conditions for amylase were pH 5.0 and $50^{\circ}C$. The activity of amylase was stable within the ranges of pH 4.0~5.0 and $20{\sim}50^{\circ}C$. The $Co^{2+}$ ion was also necessary for amylase activity, which was the highest at a 0.2%(w/v) concentration of $Co^{2+}$. The optimal pH and temperature conditions of protease were pH 8.0 and $50^{\circ}C$. The activity of protease was stable within the ranges of pH 7.0~8.5 and $20{\sim}50^{\circ}C$. Protease activity was catalyzed by $Mn^{2+}$, which was the highest at a 0.125%(w/v) concentration of $Mn^{2+}$. The isolate B. subtilis CK-2 demonstrated a high activity of autolysin. Based on these results, we identified and suggested the optimal pH, temperature, and metal ion concentration in the use of the hydrolytic enzymes of B. subtilis CK-2 for industrial purposes.

• Korean Journal of Food Science and Technology
• /
• v.26 no.2
• /
• pp.110-116
• /
• 1994

In order to study the effects of enzyme modification on the physico-chemical and functional properties of myofibrillar protein prepared from the frozen sardine, Sardinops melanostica, the protein was hydrolyzed with pepsin under the enzyme-substrate ratio 1:100 at $37^{\circ}C$ and pH 1.65 for 1, 4, 8, 12, and 24 hr, respectively. The properties of pepsin-modified sardine myofibriliar protein were determined. The extents of proteolysis with pepsin as a fuction of time was showed a typical enzyme hydorlysis curve with an initial region of 4 hour period followed by plateau region. The SDS-acrylamide slab gel electrophoresis patterns of pepsin-modified proteins showed mainly disappearances of minor protein bands, but no changes of main protein bands. The gel filtration patterns through Sephadex G-75 of sardine myofibrillar protein showed two big peaks and three small peaks. All the small peaks were disappearanced by proteolysis with pepsin in one hour. and during the period of proteolysis the fast big peak became gradually smaller and the late big peak eluted more slowly. By proteolysis, the emulsifying activity and emulsifying capacity of sardine myofibrillar protein were all decreased. The effects of pepsin-modification on emulsifying capacity were greater than those on emulsifying activity of protein. The aeration capacity of the protein was increased about 1.9 folds and the foam stability decreased to 0.6 folds of control by pepsin-modification. The pepsin-modified sardine myofibrillar proteins showed about 0.6 folds of heat coagulation and 1.4 folds of viscosity of control. The pH dependence of solubilities of sardine myofibrillar protein showed two isoelectric areas of pH 5 and 9. The pepsin-modified protein showed more clear pH dependences at the early stage but not at the late stage of proteolysis.