• Title, Summary, Keyword: pH

Search Result 41,251, Processing Time 0.1 seconds

Effect of pH on Growth and Cultural Characteristics of Bacillus sp. SH-8 and Bacillus sp. SH-8M (Bacillus sp. SH-8과 Bacillus sp. SH-8M의 생육 및 배양 특성에 미치는 pH의 영향)

  • 심창환;신원철;유주현
    • Microbiology and Biotechnology Letters
    • /
    • v.20 no.4
    • /
    • pp.371-376
    • /
    • 1992
  • The growth and cultural characteristics of Bacillus sp. SH-8 and SH-8M were investigated at various pH conditions. Bacillus sp. SH-8 showed normal growth pattern above pH 9.0. However, with the pH adjusted below 7.7, 0.$D_{550}$ decreased rapidly with concomitant reduction in viable cell numbers. In contrast, Bacillus sp. SH-8M demonstrated growth capability at pH 7.7, but with slightly reduced growth rate at pH 6.9. Similar results were obtained when those two strains were cultivated on the solid medium. Both of them showed short rod shapes at pH 10.2. However, at pH 7.7 only Bacillus sp. SH-8 was observed to have elongated rod shape. Extracellular pH of both the strains, when cultured at initial pH of 10.2, reached to 9.0 after the incubation of 28 hours. At the initial pH of 9.0 and 9.6, the extracellular pH was reduced at the beginning of cultivation, but elevated after 12 hours. When cultured at initial pH of 6.9 and 7.7, extracelluar pH of Bacillus sp. SH-8M increased to 8.0 and 8.7, respectively, while that of Bacillus sp. SH8 remained constant pH 7.0. The highest sporulation rate of Bacillus sp. SH-8 and SH-8M was obtained at the initial pH of 10.2 and after the incubation of 3 days with the sporulation rate of 95% and 85%, respectively.

  • PDF

pH Variance Model Depending on Phosphate Ion Form (인산염 이온 형태에 의한 pH 변량 모형)

  • Soh, Jae-Woo;Soh, Soon-Yil;Nam, Sang-Yong
    • Horticultural Science & Technology
    • /
    • v.33 no.6
    • /
    • pp.854-859
    • /
    • 2015
  • This experiment was performed to develop a model for nutrition ion concentration and EC in regard to change in pH from 4.0 to 8.0 in nutrient solution. The pH changes according to the variation of $HPO_4{^{-2}}$ and $H_2PO_4{^-}$ in the nutrient solution while variation of EC increased from pH 4.0 to 5.0, stabilized from pH 5.0 to 7.0 and increased again from pH 7.0 to 8.0. For the variance of major elements in the nutrient solution, K, Ca, N and P increased while pH was higher, especially the variables for K and P were increased largely. On the other hand, variables of Mg and S were stable. Based on analysis of the ion balance model of nutrient solution, the cation increased than anion over rising the variation of pH while balance point of ion moved from a-side to d-side. In addition, the imbalance increased while it moved away from the EC centerline as variance of pH increased. It was larger than effect of EC variance to correction values of equivalence ratios of K and Ca about variation of $HPO_4{^{-2}}$ and $H_2PO_4{^-}$ while as variance of pH increased, K decreased but Ca increased. These showed the result that variance of pH about correction values of equivalence ratios of K and Ca gave a second-degree polynomial model rating of 0.97. Through this research, it was identified the pH variable model about variance among pH, ion and EC according to gradient of phosphate.

Clinical Usefulness of pH Papers in the Measurement of Salivary pH

  • Song, Chan-Woo;Kim, Hye-Kyoung;Kim, Mee-Eun
    • Journal of Oral Medicine and Pain
    • /
    • v.40 no.3
    • /
    • pp.124-129
    • /
    • 2015
  • Purpose: Salivary pH is an easily measurable biochemical marker and related to various intraoral and systemic conditions. The aim of this study was to evaluate the reliability of the salivary pH measurement using pH paper. In addition, the normal values of salivary pH using pH paper were compared to those of pH meter to investigate the validity. Methods: Twenty healthy male participants attended this study (mean age, $24.5{\pm}1.47$ years). Unstimulated saliva and stimulated saliva were collected from each subject two times with the interval of a day and salivary pH was immediately measured by the two experienced examiners using pH paper and pH meter. The salivary pH was compared between the groups and inter- and intra-examiner reliability of pH paper was investigated. The intraclass correlation coefficient (ICC) was used to calculate variations. Results: All measurements had good to excellent inter-examiner (ICC 0.755 for unstimulated; 0.760 for stimulated saliva), intra-examiner (ICC 0.635 for unstimulated; 0.592 for stimulated saliva) reliability and two measurement methods using pH paper and pH paper also showed high reliability (ICC 0.852 for unstimulated; 0.640 for stimulated saliva). The values measured by pH paper were significantly lower than those measured by pH meter. Conclusions: pH paper showed adequate inter- and intra-examiner reliability and it presented the validity in terms of comparison with the pH meter as a standard in the salivary pH measurement.

Real Time Control of Dyebath pH and Dye Adsorption in Acid Dye/Nylon System(I) -Profiles for pH Control of Dyebath- (산성염료/나일론 염색에서 염액 pH와 염료흡착의 실시간 제어(I) -염액 pH의 제어 profile-)

  • Hwang Jee-Sang;Cho Hyeon-Tae
    • Textile Science and Engineering
    • /
    • v.43 no.1
    • /
    • pp.24-30
    • /
    • 2006
  • As a pre-work for real time control of dye adsorption in acid dye/nylon system, a dyebath pH control system was developed by combining chemical dosing and pH measuring equipment, dye bath analysis system, and pH control software. Three types of pH control profiles (Gaussian, exponential, and linear) were proposed for control of dyebath pH and dyeing rate. pH control results were estimated at various conditions-acid and alkali concentration, flow rate of dyeing bath, acid and alkali feed interval. The relation between the pH control profiles and adsorption behaviors of the dye was discussed. From these results, it was concluded that the Gauss type profile was more appropriate than other types for the dyebath pH control in nylon dyeing with acid dyes.

SOI 기판을 이용한 back-gated FET 센서의 pH 농도검출에 관한 연구

  • Park, Jin-Gwon;Kim, Min-Su;Jo, Won-Ju
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • /
    • pp.242-242
    • /
    • 2010
  • SiO2박막을 이온 감지막으로 이용한 pH농도센서를 제작하였다. 현재 많은 연구중인 pH센서, pH-ISFET(pH-Ion Sensitive Field Effect Transistor)는 용액과 기준전극간의 전기화학적 변위차를 이용하여 pH를 센싱한다. pH-ISFET는 기존 CMOS공정을 그대로 이용할 수 있고, 이온감지막의 변화만으로 다양한 센서를 제작할 수 있어 최근 많은 연구가 진행 중이다. 하지만 FET를 제작하기 위한 공정의 복잡성과 용액의 전위를 정해주고 FET에 바이어스를 인가해줄 기준전극이 반드시 필요하다는 제한성이 있다. 따라서 본 연구에서는 SOI 기판을 이용하여 간단한 구조의 pH센서를 제작하였다. 센서는 (100)결정면을 가지는 p-타입 SOI(Silicon On Insulator)기판을 사용하였으며 포토리소그래피 공정을 이용하여 back-gated MOSFET구조로 제작하였다. 이온감지막으로 사용할 SiO2박막은 RF 스퍼터링을 이용하여 $100{\AA}$ 증착하였다. 바이어스는 기존 pH-ISFET와는 다르게 기준전극 대신 기판을 backgate로 사용하여 FET에 바이어스를 인가해 주었다. pH 용액 주입을 위해 PDMS재질의 챔버를 제작하고 실리콘글루를 이용하여 센서에 부착하였다. pH12부터 pH4까지 단계적으로 누적시키며 챔버에 주입하였고, pH에 따른 드레인전류의 변화를 관찰하였다. pH용액을 챔버에 주입시, pH농도에 따라 제작된 센서의 문턱전압이 오른쪽으로 이동하는 결과를 관찰할 수 있었다. 결과적으로, 구조가 간단한 pseudo MOSFET을 이용하여 pH센서의 적용가능성을 확인하였으며 SiO2박막 역시 본 pH센서의 이온감지막의 역할과 센서의 안정성을 향상시킬 수 있다는 점을 확인하였다.

  • PDF

The Comparison of Various Shampoos on Skin pH in Normal Dogs (상용샴푸가 정상견의 피부 pH에 미치는 영향)

  • 오태호;박성준
    • Journal of Veterinary Clinics
    • /
    • v.18 no.4
    • /
    • pp.363-367
    • /
    • 2001
  • Shampoos are used routinely by a large number of veterinarians to treat skin diseases. Skin pH is affected by shampoos, however, known to occur. In order to evaluate the effect of shampoos on skin surface pH, we performed the measurement of skin pH using skin pH meter PH900 in five healthy mixed breed dogs. The seven commercial shampoos: Humilac, Sebocalm, Sebolytics, Etiderm, PEroxyderm, HyLyt and Zn-7 Derm were included in this study. The anatomical sites, right thorax was the highest pH (7.66$\pm$0.10), and the lowest pH (6.20$\pm$0.23) was left pinna. A statiscally significant decrease in skin pH was found 7 minutes after application of Humilac, Sebocalm, Etiderm, Peroxyderm (p<0.01) and Sebolytics (p<0.05). After 17 minutes of application skin surface pH was inclined to increase in every shampoos but the degree of increase was slight at 77 minutes. No statiscally significant differences were found in HyLy-T and Zn-7 Derm, but skin pH was normal range (6.2-7.8) after application. Throughout the experiment skin surface pH was maintained above pH 7.0 in detergent. The commercial shampoos, Humilac, Sebocalm, Etiderm, had the decreasing effect on skin surface pH in dogs. The other four shampoos maintain the skin pH normal range. The skin pH meter PH 900 was found simple and useful for skin pH measurement.

  • PDF

Regulation of Intracellular pH by SHC1 in Saccharomyces cerevisiae (효모에서 SHC1 유전자의 이온 농도 조절에 의한 세포내 pH 항상성 유지)

  • 하승길;전준철;최의열
    • Korean Journal of Microbiology
    • /
    • v.38 no.3
    • /
    • pp.168-172
    • /
    • 2002
  • Budding yeasts maintain an effective system to regulate intracellular pH in response to environmental pH fluctuation. In a previous study we reported that SHC1 plays a role in cell growth at alkaline condition, not at acid pH. We constructed a null mutant deleted an entire open reading frame for SHC1. To test whether the retardation in cell growth was caused by the absence of intracellular pH buffering capacity, we measured intracellular pH with a pH-sensitive fluorescent dye, C.SNARE. The intracellular pH of the mutant cell was much higher than that of wild-type cells, indicating that the mutant cells lack some types of buffering capacity. We also investigated the level of $Na^+ and K^+$ content with atomic mass spectroscopy after alkali shock. Wild-type cell showed a higher level of intracellular K^+$ content, whereas there was no difference in $Na^+$ level. The result suggested that K^+$ is more important in the regulation of intracellular pH in yeasts.

Effect of operational pH on anaerobic hydrogen fermentation of food waste (음식폐기물의 혐기성 수소 발효시 운전 pH의 영향)

  • Lee, Chae-Young;Lee, Se-Wook
    • Journal of the Korea Organic Resources Recycling Association
    • /
    • v.19 no.3
    • /
    • pp.73-78
    • /
    • 2011
  • The pH is one of the most important factors affecting metabolism pathway and activity of hydrogen producing bacteria. The effect of operational pH on anaerobic hydrogen fermentation of food waste was evaluated at mesophilic condition. In this batch experiment, the initial pH was 8.0 and the operational pH was controlled at 4.7~7.0 by the addition of 5N KOH solutions. At the operational pH of 4.7, the lag phase and the maximum hydrogen production were 47.9h and 534.4 mL, respectively. The lag phase and the maximum hydrogen production were decreased as the operational pH increased. At the operational pH of 7.0, the lag phase and the maximum hydrogen production were 4.2 h and 213.8 mL, respectively.

Effects of pH on Fertilization and the Hatching Rates of Far Eastern Catfish Silurus asotus

  • Gao, Yang;Kim, Sun-Gyu;Lee, Jeong-Yeol
    • Fisheries and aquatic sciences
    • /
    • v.14 no.4
    • /
    • pp.417-420
    • /
    • 2011
  • In this experiment, we examined the survival, fertilization, hatching times, and hatching rates of Far Eastern catfish Silurus asotus at pH ranging from 2 to 13 under laboratory conditions. Eggs could be fertilized at pH 3-12. In a hatching experiment, mortality was first observed at pH 13, when all fertilized eggs died within 8 min, followed by pH 2 (30 min), pH 12 (60 min), pH 3 (4 h), and pH 11 (5 h). Hatching only occurred at pH 4-10, with the highest hatching rate at pH 7 (52%) and the lowest at pH 10 (24%). Hatching rates in acid solutions were higher than in alkaline solutions, although the difference was not significant. Hatching was first observed at pH 10, beginning 27 h after fertilization and ending at the 31 h. A clear difference was observed between hatching times, ranging from 31 to 64 h and increasing in order with descending pH.

Kinetic Studies on the Mechanism of Hydrolysis of Benzohydrazonyl Bromide (Benzohydrazonyl Bromide의 加水分解 反應메카니즘에 관한 反應速度論的 硏究)

  • Ki Sung Kwon;Tae Rin Kim
    • Journal of the Korean Chemical Society
    • /
    • v.20 no.3
    • /
    • pp.221-228
    • /
    • 1976
  • The kinetics of hydrolysis of hydrazonyl bromides $(p-H,\;p-CH_3,\;p-OCH_3,\;p-Br,\;p-Cl\;&\;p-NO_2)$ have been investigated by UV spectrometry in $60{\%}$ dioxane-water at $25^{\circ}C$ and a rate equation which can be applied over wide pH range was obtained. Below pH2, the rate of hydrolysis of a series of hydrazonyl bromide is accelerated by electrondonating group (${\rho}$ = -0. 94) whereas at the pH values greater than 4, the ${\rho}$-value is 0.54. The rate equation, solvent-, substituent-and bromide ion-effect on the rate of hydrolysis are rationalized in terms of $S_N1$ and $S_N2$ mechanism: below pH 2, the hydrolysis proceed through $S_N2$, however, above pH 4, the hydrolysis is started by the attack of hydroxide ion and in the range pH 2{\sim}$4, these two reactions occur competitively.

  • PDF