• 한국염색가공학회지
• /
• 제16권1호
• /
• pp.53-58
• /
• 2004

The preparation of responsive fibers from acrylic fibers is studied. Various responsive fibers, such as fibers which change their color on exposure to light or with change in temperature, have been developed and are used commercially However, the responsive material in these fibers are not the fiber itself but chemicals in microcapsules attached to the fibers by finishing, and few fibers exhibit responsive properties by itself. The partial hydrolysis of polyacrylonitrile fibers to obtain pH responsive fibers is presented in this paper. Partial hydrolysis was effected by control of the concentration of the sodium hydroxide used in the hydrolysis, hydrolysis temperature and time. The degree of hydrolysis was evaluated by nitrogen content of the hydrolyzed fibers and their response, change in length, to aqueous solutions of varying pH was studied by continually changing the pH. Significant changes in lengths with pH were observed and the gel transition behavior varied with the conditions of hydrolysis. The hysteresis of the length change was also studied to evaluate the possibilities of using hydrolyzed acrylic fibers as pH sensors.

• Advances in nano research
• /
• 제5권3호
• /
• pp.245-251
• /
• 2017

Multiwalled carbon-nanotubes (MWCNT) and micro-structured carbon, such as biochar or activated carbon (AC), have been seen to significantly increase the growth indices of certain plant species such as maize (Zea mays L.). Seed imbibition is the stage where environmental factors that affect water transport across the seed coat barrier, make a large impact. This work explores the effect on water imbibition by maize seeds when the aqueous environment surrounding the seed is diluted by small concentrations (10 and 20 mg/l) of pristine MWCNT (p-MWCNT), carboxylate functionalized MWCNT (COO-MWCNT) and AC. The degree of sensitivity of the process to (i) large structural changes is seen by utilizing the nano (the MWCNT) and the micro (the AC) allotropic forms of carbon; (ii) to small changes in the purity and morphology of the p-MWCNT by utilizing 95% pure and 99% pure p-MWCNTs of slightly differing morphologies; and (iii) to MWCNT functionalization by using highly pure (97%) COO-MWCNT. Water imbibition was monitored over a 15 hour period by Near Infrared Thermography (NIRT) and also by seed weighing. Seed surface topography was seen by SEM imaging. Analysis of the NIRT images suggests rapid seed surface topological changes with the quantity of water imbibed. While further work is necessary to arrive at a conclusive answer, this work shows that the imbibition phase of the maize seed is sensitive to the presence of MWCNT even to small differences in the purity of the p-MWCNT and to small differences in the physicochemical properties of the medium caused by the hydrophilic COO-MWCNT.

• 한국농림기상학회지
• /
• 제5권1호
• /
• pp.24-29
• /
• 2003

강우가 산림을 통과하면서 변화하는 화학적 조성을 알아보기 위하여 강원도 춘천지역의 소나무와 리기다 소나무 임분에서 임외우와 수관통과우, 수간류를 채취하여 pH 및 용존원소를 중심으로 한 화학적 조성의 수직적인 이동특성을 구명하고자 수행한 본 연구의 결과를 요약하면 다음과 같다. 임외우의 pH의 범위는 41∼7.1 이었으며, 평균 pH는 6.2$\pm$0.1로 나타났다. 소나무 임분의 경우는 수간류가 평균 pH 5.9$\pm$0.9이었으며, 수관통과우는 pH 6.0$\pm$0.8로 측정되었다. 리기다 소나무 임분의 경우는 수간류가 pH 5.5$\pm$0.6, 수관통과우는 pH 5.8$\pm$0.7의 평균값이 측정되었다. 강우량에 따른 임외우와 임내우 (수간류, 수관통과우)의 pH 변화는 전체적으로 강우량이 적은 경우에 pH값이 넓게 분포하였으나, 강우량이 증가함에 따라 점차 감소하거나 증가하여서 안정화되는 것을 알 수 있었다. 임외우와 소나무와 리기다 소나무의 수관통과우, 수간류에서 측정한 화학적 조성의 농도 변화는 양이온 중에서는 $Ca^{2+}$의 농도 변화가 가장 크게 나타났으며, 음이온에서는 C $l^{-}$을 제외한 나머지 S $O_{4}$$^{2-}$ 와 N $O_{3}$$^{-}$에서 임외우보다 현저하게 이온 농도가 증가하거나 변화하는 것을 볼 수 있었다. 이와 같은 결과로 볼 때, 강우에 의한 수목의 용탈과 세정의 차이가 있으며, 이는 수목의 각 기관을 통과하면서 그 차이가 있다는 것을 알 수 있다.

• 한국안광학회지
• /
• 제20권1호
• /
• pp.9-14
• /
• 2015

목적: 본 논문에서는 안경테가 땀에 노출되었을 때 나타나는 변화를 알아보았다. 방법: 양백, 모넬 및 티타늄 재질의 안경테를 pH 6.5, 6.0, 5.0의 인공땀에 1주, 3주, 6주 동안 노출시킨 후 표면, 경도, 인장강도의 변화를 알아보았다. 결과: 인공땀에 의해 양백, 모넬, 티타늄 재질 안경테 표면의 부식이 유발되었으며 부식 양상은 각 재질별로 상이하였다. 인공땀의 pH와 노출시간에 비례하여 3가지 재질의 안경테 모두 경도가 감소하였으나 인장강도는 변화가 없었다. 결론: 인공땀에 의해 안경테의 표면 부식과 경도 변화가 관찰되었으므로 안경테의 일상적인 관리가 필요함을 제안한다.

• 한국농림기상학회지
• /
• 제3권3호
• /
• pp.143-149
• /
• 2001

각 지역의 겨울철 강수인 눈의 산성도와 화학적 조성과 산림지역의 임내ㆍ외 강설의 특성을 비교 분석하고자 대관령 지역(강원도 평창군 도암면 횡계리) 운교 지역(강원도 평창군 방림면 운교리)을 대상으로 강설을 채취하여 분석한 결과를 요약하면 다음과 같다. 1. 조사 지역의 강설을 채취하여 적설량과 pH의 관계를 보면, 두 지역 모두 적설량이 적을 때는 pH의 변화 분포가 크게 나타났으며, 적설량이 증가할수록 pH가 안정되는 경향을 보였다. 이와 같은 결과는 강우현상에 있어 국지적인 환경에 따른 대기중의 부유물질 중에서 산성물질의 흡착비율이 달라짐을 의미함과 동시에 광역적으로 분포하는 산성물질의 유입도 고려해야 한다는 연구(나춘기와 정재일, 1997)와 유사한 것으로 강설의 경우에도 적용할 수 있다고 판단하였다. 2. 각 조사 지역의 강설 중 임외 강설과 임내 강설의 이온농도 변화는 전체적으로 임내에서 증가하는 경향을 보였다. 이 중에서 양이온의 경우는 $Ca^{2+}$, 음이온은 NO$_{3}$$^{-}$, SO$_{4}$$^{2-}$ , Cl$^{-}$ 모두가 증가의 양상을 보였다. 3. 이러한 결과를 기초로 하여 각 이온농도간의 편차와 상호관계를 파악하기 위해서 각 이온간의 상관성과 요인분석을 실시하여 비교하는 것이 각 지역 강설의 화학적 특성을 구명할 수 있을 것으로 판단된다.

• Journal of Microbiology and Biotechnology
• /
• 제21권9호
• /
• pp.979-987
• /
• 2011

Culture pH change has some important roles in signal transduction and secondary metabolism. We have already reported that acidic pH shock enhanced actinorhodin production in Streptomyces coelicolor. Among many potential governing factors on pH variation, the putative $Na^+/H^+$ antiporter (sha) genes in S. coelicolor have been investigated in this study to elucidate the association of the sha on pH variation and secondary metabolism. Through the transcriptional analysis and overexpression experiments on 8 sha genes, we observed that most of the sha expressions were promoted by pH shock, and in the opposite way the pH changes and actinorhodin production were enhanced by the overexpression of each sha. We also confirmed that sha8 especially has a main role in maintaining cell viability and pH homeostasis through $Na^+$ extrusion, in salt effect experiment under the alkaline medium condition by deleting sha8. Moreover, this gene was observed to have a function of pH recovery after pH variation such as the pH shock, being able to cause the sporulation. However, actinorhodin production was not induced by the only pH recovery. The sha8 gene could confer on the host cell the ability to recover pH to the neutral level after pH variation like a pH drop. Sporulation was closely associated with this pH recovery caused by the action of sha8, whereas actinorhodin production was not due to such pH variation patterns alone.

• Food Science and Biotechnology
• /
• 제18권3호
• /
• pp.610-617
• /
• 2009

The stability of corn oil-in-water emulsions coated by milk proteins, sodium caseinate (CAS), or whey protein concentrate (WPC), was compared under the environmental stress of pH change. Emulsions were prepared at 0.1 of protein:oil because the majority of droplets were relatively small ($d_{32}=0.34$ and $0.35\;{\mu}m$, $d_{43}=0.65$ and $0.37\;{\mu}m$ for CAS- and WPC-emulsions, respectively) and there was no evidence of depletion flocculation. As the pH of the emulsions was gradually dropped from 7 to 3, there was no significant difference in the electrical charges of the emulsion droplets between the 2 types of emulsions. However, laser diffraction measurements, microscopy measurements, and creaming stability test indicated that WPC-emulsions were more stable to droplet aggregation than CAS-emulsions under the same circumstance of pH change. It implies that factors other than electrostatic repulsion should contribute to the different magnitude of response to pH change.

• The Korean Journal of Physiology and Pharmacology
• /
• 제7권3호
• /
• pp.131-142
• /
• 2003

We have studied mutant forms of Kir2.1 in which an aspartate residue (D172), important for gating by intracellular polyamines, is replaced by one of three basic residues (Arg, Lys or His). Such channels are highly selective for $K^+$, but show inward rectification that is a shallow function of voltage compared with that found in wild type. This inward rectification occurs with a reduced affinity for spermine and persists in the absence of polyamines. Though the unitary current-voltage relation shows some inward rectification, it is insufficient to account for that seen under whole cell recording. Channels open and shut under single channel recording, and changes of $P_{open}$ appear to generate inward rectification. In D172H, the reduction in affinity for spermine is greater when His is protonated at low $pH_i$. The effective valency for spermine is reduced from $3.09{\pm}0.07$ in wild type to $1.95{\pm}0.09$ in D172H at $pH_i$ 6.3. In the presence of dual mutants of Kir2.1, where E224 is also replaced, spermine affinity becomes undetectable. However, channels still show inward rectification and open and shut under hyper- and depolarisation, respectively. We suggest that Kir2.1 channel are able to undergo conformation changes; these changes may be important physiologically in generating inward rectification, the normal parameters of which are set by the binding of polyamines such as spermine.

• Journal of Ecology and Environment
• /
• 제36권1호
• /
• pp.31-38
• /
• 2013

Annual ring formation is considered a source of information to investigate the effects of environmental changes caused by temperature, air pollution, and acid rain on tree growth. A comparative investigation of annual ring growth of Cryptomeria japonica in relation to environmental changes was conducted at two sites in southern Korea (Haenam and Jangseong). Three wood disks from each site were collected from stems at breast height and annual ring growth was analyzed. Annual ring area at two sites increased over time (p > 0.05). Tree ring growth rate in Jangseong was higher than that in Haenam. Annual ring area increment in Jangseong was more strongly correlated with environmental variables than that in Haenam; annual ring growth increased with increasing temperature (p < 0.01) and a positive effect of $NO_2$ concentration on annual ring area (p < 0.05) could be attributed to nitrogen deposition in Jangseong. The correlation of annual ring growth increased with decreasing $SO_2$ and $CO_2$ concentrations (p < 0.01) in Jangseong. Variation in annual growth rings in Jangseong could be associated with temperature changes and N deposition. In Haenam, annual ring growth was correlated with $SO_2$ concentration (p < 0.01), and there was a negative relationship between precipitation pH and annual ring area (p < 0.01) which may reflect changes in nutrient cycles due to the acid rain. Therefore, the combined effects of increased $CO_2$, N deposition, and temperature on tree ring growth in Jangseong may be linked to soil acidification in this forest ecosystem. The interactions between air pollution ($SO_2$) and precipitation pH in Haenam may affect tree growth and may change nutrient cycles in this site. These results suggested that annual tree ring growth in Jangseong was more correlated with environmental variables than that in Haenam. However, the further growth of C. japonica forest at two sites is at risk from the long-term effects of acid deposition from fossil fuel combustion.

• Journal of Chest Surgery
• /
• 제12권4호
• /
• pp.395-402
• /
• 1979

Intracellular pH was determined by distribution of 5.5-dimethyl-2,4-oxazolidlnedione [DMO]in the skeletal muscle of dogs before and after lactic acidosis induced by intravenous infusion of lactic acid solution. After infusion of lactic acid solution arterial pH decreased from 7.40 to around 7.12 [P<0.001]and metabolic acidosis was induced. However, dose-pH change response was not proportional as in the case of hydrochloric acid infusion. During lactic acidosis, intracellular pH changed very little except when venous blood $pCO_2$ increased significantly. The decrease of intracellular pH in lactic acidosis might be due primarily to the increase of intracellular $pCO_2$. And during lactic acidosis, change of extracellular pH was larger than that of intracellular pH, and this was also the case of change In hydrogen Ion concentration in extracellular and intracellular fluid. The fact was estimated that exogenous lactic acid transported into the cell does not contribute to pH change by the participation in the metabolism. Change in plasma potassium Ion concentration was not eminent as metabolic acid-base disturbances by other origin, and changing pattern of Hi/He ratio was not same as Ki/Ke ratio. In spite of no changes in extracellular potassium ion concentration after exogenous lactic acidosis total amount of potassium ion in extracellular fluid increased from 12.62mEg to 18.26mEg [P< 0.05].