• Journal of the Microelectronics and Packaging Society
• /
• v.26 no.3
• /
• pp.59-62
• /
• 2019

In this study, we have developed solution-processed, F-doped In-Ga-Zn-O semiconductors and investigated their applications to thin-film transistors. In order for forming the appropriate channel layer, precursor solutions were formulated by dissolving the metal salts in the designated solvent and an additive, ammonium fluoride, was incorporated additionally as a chemical modifier. We have studied thermal and chemical contributions by a thermal annealing and an incorporation of chemical modifier, from which it was revealed that electrical performances of the thin-film transistors comprising the channel layer annealed at a low temperature can be improved significantly along with an addition of ammonium fluoride. As a result, when the 20 mol% fluorine was incorporated into the semiconductor layer, electrical characteristics were accomplished with a field-effect mobility of $1.2cm^2/V{\cdot}sec$ and an $I_{on}/_{off}$ of $7{\times}10^6$.

• Journal of the Korean Chemical Society
• /
• v.23 no.4
• /
• pp.237-242
• /
• 1979

The equivalent conductances of sodium, potassium, ammonium, tetramethylammonium, triethylammonium, diethylammonium and ethylammonium iodide, and picrate salts of sodium and potassium in ethylene carbonate have been measured at 40.0 $^{\circ}C. The limiting equivalent conductances of the salts have been computed by Fuoss-Onsager-Skinner equation. The limiting ionic equivalent conductances of $Na^+,\;K^+,\;and\;NH^+$ are in order of $Na^+ which is the reverse order of solvation for the ions in any solution, And the order of limiting ionic equivalent conductances for alkylammonium ions is $(C_2H_5)_4N^+<(C_2H_5)_3NH^+<(CH_3)_4N^+<(C_2H_5)_2NH_2^+<(C_2H_5)NH_3^+$ which coincides with the order of mass transfer. From the dissociation constants of the saltss determinde by Fuoss-Kraus method, it is found that ethyene carbonate is a good ionizing solvent for the salts. In addition, Stokes radii and effective fadii of ions have been calculated by Stokes law and Nightingale method, repectively. From the results, it appears tha alkylammonium ions and picrate ion seem to be not solvated, and tha iodide ion is fairly solvated in ethylene carbonate.

• Journal of Environmental Science International
• /
• v.24 no.5
• /
• pp.615-622
• /
• 2015

East Asia is characterized by anthropogenic emissions resulting from the large population and fast economic growth of this region. Since the prevailing wind is westerly and northwesterly, emissions from Ul-jin can be expected to contribute to acidic deposition increase in downwind direction. Aerosols collected at the near coast site, Uljin geun, gyungbook and were analyzed for $NH_4{^+}$, $Mg^{2+}$, $Na^+$, $Ca^{2+}$, $Cl^-$, $SO_4{^{2-}}$, and $NO_3{^-}$ from Aug. 2012 to Feb. 2013. The seasonal averaged aerosol concentration showed the highest potassium and calcium ion in winter and the highest ammonium ion due to a meadow and high solar intensity in summer. Sodium and chloride ion showed the same ratio all seasons and sulfate and nitrate species showed the maximum value in winter Chemical components of aerosols collected at the near coast site, Uljin geun, gyungbook were lower by 16 to 73% than those collected at other similar environment site such as kanghwa, yangyang. Comparing air quality data at the near coast site, Uljin geun, gyungbook, There was found that Uljin coast site is less influenced by the sea salts(potassium, magnesium, calcium) and nss-$SO_4{^{2-}}$ percentage is 3~13% higher than similar condition site.

• Journal of Microbiology and Biotechnology
• /
• v.4 no.2
• /
• pp.126-133
• /
• 1994

A Pseudomonas putida strain able to accumulate high amount of polyesters of medium-chain-length 3-hydroxyalkanoic acids ($PHA_{MCL)$) was isolated from soil in a landfill site using an enrichment technique. Culture condition of the isolated strain for polyester production in a one-step culture was optimized in a mineral-salts medium against pH and concentrations of ammonium sulfate, carbon source(e.g., octanoate), and phosphate. The optimal values for maximal cell growth and PHA accumulation were: pH; 7$\sim$8, $(NH_4)_2SO_4$; 8 mM, octanoate; 40 mM. The optimum temperature was in the range of $20\sim30^{\circ}C$, which was rather broader than in other bacteria. Cell growth was strongly inhibited by the phosphate limitation to less than 1 mM. An increase of phosphate concentration above 1 mM showed little effect on cell growth and polyester accumulation. When the strain was grown on octanoate under this optimized condition it produced 3.4 g dry biomass per liter and yielded 1.7 g PHA per liter amounting to 53 wt% of dry cells. The monomer units composing the polyester synthesized from octanoate were 3-hydroxyoctanoate (3HO), 3-hydroxycaproate (3HC), and 3-hydroxybutyrate (3HB) (85:13:2, mole ratio). Other low linear $C_3\simC_{10}$ monocarboxylic acids were also tested for polyester production.

• Korean Journal of Microbiology
• /
• v.20 no.3
• /
• pp.119-124
• /
• 1982

As a basic study to elucidate nutritional physiology and composition of synthetic medium of red rotting bacteria, Erwinia carotovora, of ginseng, the effects of hydrogen ion concentration, various kinds of carbon sources, nitrogen source, micrometallic salts and it's concentration on the gorwth of the bacteria were investigated and the results were as follows. Optimal pH in the basal medium for the growth of the bacteria was 6.5. After incubation the pH in culture media was neutralized. Among the various kinds of carbon sources, sucrose, glucose mannitol, but organic acids were not utilized effectively as nutrients. After incubation the pH turned acidic. Alanine as organic nitrogen sources nad ammonium sulfate as inorganic nitrogen promoted the growth, but L-valine and sodium nitrite were the least effective. Ferric chloride 1.0mg/dl and ferrous sulfate 100mg/dl were the most effective as micrometallic sources. Control and boric acid were the least effective. New synthetic medium based on the above results was follows ; Alanine 1.0g, $KH_2PO_4\;1.0g, \;sucrose\;30.0g, \;MgSo_4{\cdot}7H_2O\;0.5g, \;FeCl_3{\cdot}6H_2O\;1.0mg\;thiamine\;200{\gamma}g$, and distilled water 1000ml, pH6.5.

• Journal of Microbiology and Biotechnology
• /
• v.16 no.1
• /
• pp.52-56
• /
• 2006

The effect of bensulfuron-methyl on the nontargeted cyanobacteria was greater on A. variabillis than N. commune. Both A. variabillis and N. commune were initially able to utilize low concentrations of the herbicide, bensulfuron-methyl, whereas higher concentrations of bensulfuron-methyl or the hydrolyzed products of the herbicide were found to be toxic. Growth and photosynthesis inhibitions of over $50\%$ were observed, when 8 to 10 ppm of the herbicide was applied. Nitrogenase activities of the cyanobacteria were decreased by $94-98\%$ in A. variabillis and by $85-86\%$ in N. commune after 24 h of incubation with 10 ppm and 20 ppm of bensulfuron-methyl. Nitrogenase activities were also inhibited by the addition of ammonium salts as low as 0.05 mM. Furthermore, the toxic effect of the herbicide was the highest at pH 4-6, showing approximately $42-60\%$ toxicity, whereas much lower toxicity $(9-28\%)$ was observed at higher pH of 7-10, due to base-catalyzed hydrolysis of bensulfuron-methyl.

• Journal of Microbiology and Biotechnology
• /
• v.15 no.4
• /
• pp.899-902
• /
• 2005

Peptide assimilation by Helicobacter pylori was investigated using L-phenylalanyl-3-thia-phenylalanine (PSP) as a detector peptide; the release of thiophenol upon enzymatic hydrolysis of PSP was spectrophotometrically detected with the aid of 5,5'-dithiobis[2-nitrobenzoic acid] (DTNB). By adding PSP to whole-cell suspension, thiophenol was produced progressively, resembling that found in Esherichia coli or Staphylococcus aureus. Interestingly, the rate of thiophenol production by H pylori in particular was markedly reduced when cells were pretreated with trypsin, indicating surface exhibition of peptidase. According to the competitive spectrophotometry using alanyl-peptides, H pylori did not appear to assimilate PSP through the peptide transport system. No discernible PSP assimilation could be ascertained in H pylori cells, unless provided with some additives necessary for peptidase activity, such as $Ni^{2+}\;or\;Mg^{2+}$ and an appropriate concentration of potassium or ammonium salts. These observations strongly suggest that, regardless of a presumptive peptide transport system, peptide assimilation of H. plori appears to be highly dependent upon milieu conditions, due to unique peptidase exhibition on the cell surface.

• Microbiology and Biotechnology Letters
• /
• v.7 no.2
• /
• pp.65-70
• /
• 1979

By the successive enrichment culture, methanol-utilizing bacteria of 213 strains were isolated from soil samples collected from various places. Among them one strain showing excellent growth was selected. The organism isolated was obligate methylotroph and identified as Methylomonas methanolica on the basis of its mophological and physiological characteristics of the cell. The medium have been to be collected for the maximum biomass productivity. The microorganism was capable of growing satisfactorily on a medium containing only methanol 0.8％ (v/v), ammonium sulfate 0.6％, magnesium sulfate 0.1％, phosphate salts, but did not require growth factor.

• Journal of the Korean Applied Science and Technology
• /
• v.6 no.2
• /
• pp.29-37
• /
• 1989

Using the quarternary ammonium salts as phase transfer catalyst, the nucleophilic substitution reaction of 1-chlorooctane with sodium-cyanide was investigate kinetically with respect to the formation of octanenitrile. The product was analyzed with gas chromatograph, and quantity of octanenitrile was measured. The reaction condition was considered by the effect of the reaction temperature, of the species and the amount of catalyst, of the speed of strirring, and of the concentration of reactants. The reaction was carried out in the first order on the concentration of 1-chlorooctane and sodium cyanide, respectively. The over-all order was 2nd. The activation energies for the nucleophilic substitution reaction of 1-chlorooctane and 1-bromooctane under tetrabutylammonium hydrogen-sulfate were calculated as 2.05 and 10.08kcal/mol, respectively. The effect of various caltalysts was decreased in the order of tetrabutylammonium bromide, terabutylammonium, tetrabutylammonium hydrogensulfate, and tetrabutylammonium iodide. The reaction rate was dependent on the concentration of sodium-cyanide dissolved in the aqueous phase, and the good result was shown when the mol ratio between 1-chlorooctane and sodium cyanide was one per three.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.173-173
• /
• 2017

Phalaenopsis orchid is one of the most important flowers in flower industry. We conducted an experiment to find out the response of different concentration of chlorocholine chloride (CCC) for the in vitro regeneration of protocorm like bodies (PLBs) of Phalaenopsis 'Fmk02010'. We used five different concentrations of CCC and these were 0 (control), 0.01, 0.1, 1 and $10mgL^{-1}$ in modified MS medium and cultured for 42 days. We added two major salts ammonium nitrate ($412.5mgL^{-1}$) and potassium nitrate ($950.0mgL^{-1}$) to the MS medium for the modification. Maximum numbers of PLBs were found from media with $0.01mgL^{-1}$ of CCC (15.667) and maximum fresh weight (0.211 g) as well. The 100% PLB formation rate was also found from $0.01mgL^{-1}$ of CCC. We found 58.83% variation in number of PLBs ($R^2=0.5883$) and 47.44% variation in fresh weight ($R^2=0.4744$) to the different CCC concentrations. Our study suggested that increase in the CCC concentration negatively affect the PLBs organogenesis of Phalaenopsis. We can suggest that the addition of very low concentration of CCC in plant culture medium can increase the number, formation rate and fresh weight of PLBs of Phalaenopsis.