• Journal of the Korean Chemical Society
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• v.9 no.3
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• pp.128-133
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• 1965

Hydrazonium diphosphate crystallizes with the space-group symmetry $P2_1/C.$ There are two formular units of $N_2H_6H_4(PO_4)_2$ in the unit cell, for which $a = 4.52{\pm}0.02, b = 8.06{\pm}0.03, c = 10.74{\pm}0.03{\AA}\;and\; {\beta} = 100{\pm}0.5^{\circ}.$ The determination of the crystal structure was carried out by means of Patterson, Fourier and difference syntheses. The phosphate group has configuration of nearly regular tetrahedron with the mean P-O distance of $1.55{\AA}.$ The N-N distance found is $1.40{\AA},$ which corresponds to previously reported values for the $N_2H_6^{++} \;ion \;in\; N_2H_6SO_4.$ A molecule has a transform with a center of symmetry in it. Each nitrogen atom forms three hydrogen bonds with the N…O distances 2.62, 2.79 and $2.89{\AA}.$ And a O…O hydrogen bond between different phosphate groups is found with the distance $2.63{\AA}.$ The structure is held together by three-dimensional network of the strong hydrogen bonds.

• Applied Biological Chemistry
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• v.11
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• pp.55-61
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• 1969

This K-17 strain was not absolutely requiring xylose as an inducer for enzyme formations. The most activity of this enzyme was lost when treated at $75^{\circ}C$. for 30 hours but was not influenced at $70^{\circ}C$. for 70 hours of treatment. The activity of this enzyme was increased by the addition of magnesium ions or cobalt ions in the reaction system. In the studies, we found that the magnesium ions simply activate the enzyme reaction and the cobalt ions do not but protect the enzyme from heat inactvation. And it was also found the phosphate buffer solution was very suitable as glucose dissolving solvent on the enzyme reaction. The mixed carbon source medium containing glucose, fructose, sorbitol, xylose and sucrose was more favorable for enzyme production then a sole carbon source containing medium on the shaking culture method.

• Korean Journal of Poultry Science
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• v.17 no.2
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• pp.109-114
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• 1990

Enzymatic activity of isolated Lysozyme from egg white by cation ion-exchange chromatography was detected with various methods and stability of lysozyme in solution was studied by heat and pH treatments. Lysozyme activity refered to mg pure lysozyme/mg sample was more accurate although it needed standard lysozyme. But lysozyme activity refered to units/mg sample could be detected easily and reducted total detection time. Enzymatic activity of isolated lysozyme which dissolved in 0.066M phosphate buffer(pH 6.3) and then incubated at $37^{\circ}C$ for 2hr was increased remarkably on the lysis of Micrococcus lysodeikticus. The activity of isolated lysozyme by CM Sephadex C-25 was higher in eluting solution of above O. D. 1.0 at 640nm and attained 36, 000 units/mg solid. The stability of isolated lysozyme was decreased by various heat treatment. Activity began to decrease above 6$0^{\circ}C$ and dropped rapidly at $100^{\circ}C$. Especially, 35% loss of activity occured in 0.066M phosphate buffer at $100^{\circ}C$. for 15min. The stability of lysozyme was also affected by pH. lysozyme was very stable in acidic solution but in alkaline solution. Enzymatic activity showed maximum value at pH 3.0 solution while decreased rapidly above pH 6.0 solution.

• Journal of the Korean Chemical Society
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• v.66 no.2
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• pp.86-91
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• 2022

The manure made of chaff and sawdust as litter was collected separately at a cowshed of a livestock farm in Andondg city. The fermentation efficiency of excreta is greatly influenced by the type and characteristics of litter and a factor to be considered for reducing N and P, the causes of eutrophication. Changes in weight with temperature and constituents of sample were examined using TG-DTA and XRF, respectively. NO₂^-, NO₃^-, and PO₄^3- ions and NH₄⁺, T-P and T-N eluted from manure by rain were analyzed using ion chromatograph and UV/Vis spectrometry, respectively. As a result, the fermentation efficiency of excreta in sawdust manure is three times higher as compared with chaff manure. The higher the fermentation efficiency, ammonia nitrogen was highly de-nitrogenated and organic phosphorous were also changed into phosphorous ions. Furthermore, phosphorous ions can be removed by transforming insoluble salts such as calcium phosphate (CaHPO₄·3H₂O) and struvite (NH₄MgPO₄·6H₂O) with addition of Ca and Mg.

• Journal of Food Hygiene and Safety
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• v.13 no.3
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• pp.252-257
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• 1998

Bamboo salt has been used as a traditional remedy for gastric ulcer and gastro-intestinal disorders. It is produced by baking the salt packed in bamboo cylinder nine times under the fire of pine tree. Three of commercially available bamboo salt products (bamboo salt A, B, and C) were characterized by qualitative and quantitative analyses using inductively coupled plasma (ICP) spectrometer, ion chromatograph (IC), X-ray diffractometer (XRD), and electron microscope (EM). Compared with crude salt, the contents of iron, silicon, potassium, and phosphate in the bamboo salt products were higher whereas the sulfate content was lower. Water-insoluble fraction of bamboo salts contained the following compounds; MgO, $SiO_2,\;Mg_2Si0_4,\;and\;CaMgSi0_4$. The study on the microscopic structures of the bamboo salts were shown to have smooth surface and fused shape compared with crude salt. Among the three bamboo salt products, product A was used to test a possible inhibitory effect on gastric acid secretion. Each test material (bamboo salt A, crude salt, and reagent-grade NaCl) was given orally to Sprague-Dawley rats at doses of 0.2, 1.0, and 2.0 g/kg for 28 days before pyrolus ligation. Twenty four hours after the last administration of the test materials, volume, pH, total acidity, and pepsin activity of gastric juice were measured by the Shay-ligation method. No significant differences were observed in the secretion of gastric acid between treated groups (bamboo salt-, crude salt- and reagent-grade NaCI-treated groups) and control group (distilled water-treated group). This result demonstrated that bamboo salt did not exert anti-ulcer activities in experimental animals used in the present study.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.5
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• pp.589-594
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• 2007

The effect of synergists having chelating ability on inhibiting browning were studied with a giucose-glutamic acid model for doenjang containing citric acid as the anti-browning agent and iron ion. The model solutions were prepared by dissolving 0.1 M glucose, 0.1 M glutamic acid, 50 mM citric acid, 0.2 mM $FeCl_2$ and synergist in 1 M phosphate buffer (pH 7.0), heating at $50^{\circ}C$ for 24 hr and storing at $30^{\circ}C\;or\;40^{\circ}C$ for four weeks. Synergists were chitosan, gallic acid, methyl benzoate, pyrophosphate and tannic acid; they were used at the following concentrations: gallic acid, pyrophosphate and tannic acid at 0.015% and 0.15%; chitosan and methyl benzoate at 0.0075% and 0.015%. Anti-browning capacities had a tendency to decrease greatly after three weeks in the case of storage at $30^{\circ}C$, whereas they decreased with storage time during storage at $40^{\circ}C$. However, anti-browning capacities of samples containing 0.015% tannic acid and 0.15% pyrophosphate were higher than that of sample without synergist by 32% after storage at $30^{\circ}C$ for four weeks. Gallic acid, tannic acid and pyrophsphate also inhibited the formation of Maillard reaction intermediates such as fluorescent compound and 3-deoxyglucosone due to the high chelating ability with iron ion after four weeks of storage at $30^{\circ}C$. The effect of these compounds on the inhibition of formation of Maillard reaction intermediates was higher at 0.15% than at 0.015%. Moreover, gallic acid increased the browning by forming colored complexes, and tannic acid generated black precipitates. Therefore, pyrophosphate of food additives was found to be the most useful synergist of citric acid, the anti-browning agent for doenjang.

• Korean Journal of Food Science and Technology
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• v.32 no.1
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• pp.161-167
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• 2000

The protease produced by a newly isolated Aspergillus wentti from Korean traditional Meju was purified and characterized. The optimal medium composition and culture conditions for maximum protease production were ; bran :1% glucose solution =1 : 1, pH 9.0, $30^{\circ}C$, and 4 days of fermentation. Protease was purified by QAE-Sephadex, SP-Sephadex ion exchange chromatography and Sephadex G-100 chromatography. The specific activity and the purification fold of the purified enzyme were 213 unit/mg protein and 27.3, respectively. The molecular weight of purified protease was found to be 32 kDa by SDS-PAGE. Km and Vmax value's for hammastein milk casein were $3.049{\times}10^{-4}\;M\;and\;151.1\;{\mu}g/min$, respectively. Kinetic parameters showed that the enzyme has higher affinity to casein than isolated soybean protein, hemoglobin and bovine serum albumin. Optimal pH and temperature for reaction of the purified enzyme were 9.0 and $50^{\circ}C$, respectively. The enzyme was stable at pH 4.0-11.0, below $40^{\circ}C$, and the activity was not stimulated by metal ions. 1mM phenylmethylsulfonyl fluoride inhibited the enzyme activity by 98.5%. It means that the enzyme is one of serine protease.

• Analytical Science and Technology
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• v.19 no.5
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• pp.433-440
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• 2006

A HPLC/UV method was developed and validated for the rapid and simultaneous determination of urinary metabolites of organic solvents, mandelic acid, hippuric acid, phenylglyoxylic acid, ortho-, meta- and para-methylhippuric acid, using a monolithic column. The mobile phase was composed of tetrabutylammonium bromide as ion-pairing reagent with a flow rate of 2.4 mL/min. The total run time was less than 2.5 min for all six analytes. Good linearities were obtained for all the metabolites with correlation coefficients above 0.9993. Intra-day precision, accuracy and inter-day precision was 0.01~7.32%, 83.9~116.3% and 0.01~7.16%, respectively. The method was validated and confirmed by quantification of the quality assurance samples of Industrial Safety and Health Research Institute, Korea Occupational Safety and Health Agency.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1783-1790
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• 2013

A simultaneous analytical method has been developed for the fluorimetric determination of haloacetonitriles (HANs) [dichloroacetonitrile (DCAN), trichloroacetonitrile (TCAN), dibromoacetonitrile (DBAN), haloacetamides [dichloroacetamide (DCAD), and trichloroacetamde (TCAD)] in drinking water by using the combined on-line perconcentration/reversed phase liquid chromatography (RPLC)-postcolumn detection system. This on-line perconcentration system was achieved by employing a precolumn packed with a commercial solid phase extraction (SPE) sorbent for the enrichment and purification of the target analytes. The haloacetonitriles and haloacetamides were separated on CN analytical column in a 7.5% methanol-0.02 M phosphate buffered mobile phase at pH 3. The column effluents were reacted with postcolumn reagents of ophthaldialdehyde (OPA) and sulfite ion at pH 11.5, to produce a highly fluorescent isoindole fluorophore, which were measured with a fluorescence detector. Under the optimized conditions for RPLC and the postcolumn derivatization system all of the coefficient of determination of the standard calibration curves for the target analytes were over 0.99 and had a linear range from 5 to 100 ${\mu}g/L$. The detection limits showed 1.6 ${\mu}g/L$ for DCAD, 0.1 ${\mu}g/L$ for TCAD, 0.6 ${\mu}g/L$ for DCAN, 1.6 ${\mu}g/L$ for TCAN and 1 ${\mu}g/L$ for DBAN, and the recoveries were ranged from 64 to 99% except for DCAD with precisions less than 4.9% in distilled water, and from 72(${\pm}4%$) to 116%(${\pm}2%$) in tap water.

• Journal of Surface Science and Engineering
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• v.50 no.3
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• pp.147-154
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• 2017

This research was conducted to investigate the electrochemical properties of the thin air-formed oxide film-covered AZ31 Mg alloy. Native air-formed oxide films on AZ31 Mg alloy samples were prepared by knife-abrading method and the changes in the electrochemical properties of the air-formed oxide film were investigated in seven different electrolytes containing the following anions $Cl^-$, $F^-$, $SO{_4}^{2-}$, $NO_3{^-}$, $CH_3COO^-$, $CO{_3}^{2-}$, and $PO{_4}^{3-}$. It was observed from open circuit potential (OCP) transients that the potential initially decreased before gradually increasing again in the solutions containing only $CO{_3}^{2-}$ or $PO{_4}^{3-}$ ions, indicating the dissolution or transformation of the native air-formed oxide film into new more protective surface films. The Nyquist plots obtained from electrochemical impedance spectroscopy (EIS) showed that there was growth of new surface films with immersion time on the air-formed oxide film-covered specimens in all the electrolyte. The least resistive surface films were formed in fluoride and sulphate baths whereas the most protective film was formed in phosphate bath. The potentiodynamic polarization curves illustrated that passive behaviour of AZ31 Mg alloy under anodic polarization appears only in $CO{_3}^{2-}$, or $PO{_4}^{3-}$ ions containing solutions and at more than $-0.4V_{Ag/AgCl}$ in $F^-$ ion containing solution.