• Title/Summary/Keyword: Acid-base

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Utilization of Pine Bark(II) -Characterization of Mg- and Na-base Acid Sulfite Cooking- (소나무 수피(樹皮)의 총합적(總合的) 이용(利用)(II) -Mg- 및 Na-base 산성(酸性) 아황산염(亞黃酸鹽) 증해(蒸解) 특성(特性)-)

  • Mun, Sung-Phil;Kim, Jae-Phil
    • Journal of the Korean Wood Science and Technology
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    • v.22 no.1
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    • pp.34-39
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    • 1994
  • Effects of Mg-base acid sulfite and Mg- or Na-base bisulfite on pine bark cooking were examined. In the presence of 75 % free acid at 145 $^{\circ}C$, the rate of cooking and delignification was improved with the increase of total acid. However, the delignification could not be achieved by 50 % or more under these cooking conditions. When cooked with 50~65 % free acid and at 155~165 $^{\circ}C$, the rate of cooking and delignification was remarkably improved. Thus, the bark was delignified up to 73 % when cooked for 2 hours in the presence of 50 % free acid and 24 % total acid. Na-base bisulfite was slightly more effective than Mg-base bisulfite for cooking, giving 76 % delignification of pine bark. However, there was no significant difference in selectivity of delignification between Na- and Mg-base bisulfite cooking.

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An Understanding of Elementary School Students on the Acid-Base, Acid Rain and Soil Acidification (초등학생들의 산-염기, 산성비, 토양산성화에 대한 이해)

  • KIM, Sung-Kyu
    • Journal of Fisheries and Marine Sciences Education
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    • v.27 no.6
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    • pp.1764-1782
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    • 2015
  • The purpose of this study is to investigate the understanding on the acid-base, acid rain and soil acidification of the elementary students. The participants in the current study were 280 6th graders from a elementary school in Gyeongnam Province. A questionnaire consists of four categories: understanding of (a) acid-base basic knowledge, (b) acid rain and (c) soil acidification. (d) In addition, students were asked to comment about the introduction of the acid rain experiment in the science textbook. The results are as follows; First, the results regarding acid-base basic knowledge. They know the classification, characteristics, and properties of acid-based solutions well but they don't know the acid-base neutralization, examples using properties and application in real life. Second, the results regarding acid rain, students know the definition and damage of acid rain but they don't know the causing substances, emission source and way of solution of acid rain for lack of knowledge. Third, the results regarding soil acidification was the well-known part for the students because they had continued learning about the soil from the lesson of acid rain. Also, we looked into the difference in gender and region about the understanding of acid-base, acid rain and soil acidification. According to the gender of the data about the understanding of acid-base, acid rain and soil acidification, the percentage of correct answers of female was higher than male's. Also we expected that urban students were higher than rural students on the understanding of acid-base, acid rain and soil acidification, but the understanding of urban students were similar to rural students. Fourth, we got positive answers and negative answers to the introduction of acid rain experiment. Most of the positive opinion were I want to know a lot acid rain experiment", followed by "It is possible to prevent the risk of the damage and It seems to having fun and new order. Most of the negative opinion were Acid rain experiment may be difficult and complicated followed by Just a theory in the book is enough, Acid rain experiment were boring and not fun, Acid rain experiment is dangerous, There are many to study in this order.

A comparison of traditional and quantitative analysis of acid-base and electrolyte imbalance in 87 cats

  • Chun, Daseul;Yu, DoHyeon
    • Korean Journal of Veterinary Research
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    • v.61 no.4
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    • pp.40.1-40.6
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    • 2021
  • Acid-base disorder is a common problem in veterinary emergency and critical care. Traditional methods, as well as the Stewart method based on strong ion difference concepts and the Fencl-Stewart method, can be used to analyze the underlying causes. On the other hand, there are insufficient comparative study data on these methods in cats. From 2018 to 2020, 327 acid-base analysis data were collected from 69 sick and 18 healthy cats. The three most well-known methods (traditional method, Stewart method, and Fencl-Stewart method) were used to analyze the acid-base status. The frequency of acid-base imbalances and the degree of variation according to the disease were also evaluated. In the traditional acid-base analysis, 5/69 (7.2%) cats showed a normal acid-base status, and 23.2% and 40.6% of the simple and mixed disorders, respectively. The Fencl-Stewart method showed changes in both the acidotic and alkalotic processes in 64/69 (92.8%), whereas all cats showed an abnormal status in the Fencl-Stewart method (semiquantitative approach). The frequencies of the different acid-base imbalances were identified according to the analysis method. These findings can assist in analyzing the underlying causes of acid-base imbalance and developing the appropriate treatment.

Acid-base Reaction (산-염기 반응)

  • Lee, Man-Seung
    • Resources Recycling
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    • v.27 no.5
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    • pp.3-8
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    • 2018
  • Acid-base reaction together with oxidation-reduction reaction is an important reaction occurring in the aqueous phase. The definition by Lewis on the acid and base is more comprehensive than several definitions. HSAB theory has been introduced to consider the difference in the reactivity among the acids/bases. In this paper, several acid-base reactions were analyzed by applying the definition of acid and base. Moreover, the background of the introduction of HSAB and its application was explained.

Probing Understanding of Acid and Base Concepts of the 3rd-Grade Students in Middle School (중학교 3학년 학생들의 산 · 염기 개념 이해조사)

  • Kang, Soon Hee;Cho, Sung Ah
    • Journal of the Korean Chemical Society
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    • v.43 no.6
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    • pp.707-719
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    • 1999
  • This article studies the understanding of acid and base concepts of the 3rd-grade students in middle school. An effective teaching strategy for improving their acid and base concepts was designed by considering students' prior knowledge using Lawson's learning cycle method. The control group was adapted by the traditional teaching strategy which isn't considering students' prior knowledge. After the class, understanding of acid and base concepts of treatment group was significantly higher than that of control group. But the level of students' understanding of strong acid, weak acid strong base and the strength of acid in aqueous solution was low even after the class of two groups. This indicates indirectly that the microscopic views of acid and base concepts in aqueous solution are not easy to learn for these students. For the four categories of acid and base concepts, students' responses were reviewed carefully and classified into scientific conceptions and misconceptions. These results will be useful for developing an effective teaching strategy of acid and base concepts.

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Utilization of Pine Bark(I) -Chemical Compositions and Characterization of Ca-base Acid Sulfite Cooking of Pine Bark- (소나무 수피(樹皮)의 총합적(總合的) 이용(利用)(I) -수피(樹皮)의 화학적(化學的) 조성(組成)과 Ca-base 산성(酸性) 아황산염(亞黃酸鹽) 증해(蒸解) 특성(特性)-)

  • Mun, Sung-Phil;Kim, Jae-Phil
    • Journal of the Korean Wood Science and Technology
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    • v.22 no.1
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    • pp.28-33
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    • 1994
  • The chemical compositions of pine bark from mechanical pulp industry were determined, and effect of Ca base acid sulfite on bark cooking was investigated under various conditions. The pine bark was composed of 39.5 % alkali extractives, 50.3 % lignin, and a small amount of carbohydrate. The contents of alkali extractives and lignin were remarkably higher than those of pine wood. The bark was composed of high content of arabinose and xylose, while the wood was composed of high content of mannose. When pine bark was cooked with 75 % free acid at 145 $^{\circ}C$, the rate of cooking and delignification was improved with the increase of total acid, but it was very difficult to delignify the bark by 50 % and over under these conditions. In the presence of 60~65 % free acid and at 155~165 $^{\circ}C$, initial cooking rate, delignification, and delignification selectivity were considerably increased, but condensation reaction of lignin was considerable at the end of cooking. Therefore, it was shown that pine bark was very difficult to delignify by the Ca-base acid sulfite cooking.

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Acid-Base Bifunctional Metal-Organic Frameworks: Green Synthesis and Application in One-Pot Glucose to 5-HMF Conversion

  • Zhang, Yunlei;Jin, Pei;Meng, Minjia;Gao, Lin;Liu, Meng;Yan, Yongsheng
    • Nano
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    • v.13 no.11
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    • pp.1850132.1-1850132.14
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    • 2018
  • The direct synthesis of metal-organic frameworks (MOFs) with acidic and basic active sites is challenging due to the introduction of functional groups by post-functionalization method often jeopardize the framework integrity. Herein, we report the direct synthesis of acid-base bifunctional MOFs with tuning acid-base strength. Employing modulated hydrothermal (MHT) approach, microporous MOFs named $UiO-66-NH_2$ was prepared. Through the ring-opening reaction of 1,3-propanesultone with amino group, $UiO-66-NH_2-SO_3H-type$ catalysts can be obtained. The synthesized catalysts were well characterized and their catalytic performances were evaluated in one-pot glucose to 5-HMF conversion. Results revealed the acid-base bi-functional catalyst possessed high activity and excellent stability. This work provides a general and economically viable approach for the large-scale synthesis of acid-base bi-functional MOFs for their potential use in catalysis field.

Wear Characteristics of Polyolester Base Oils Baying different Branch Shapes(I) (서로 다른 모양의 가지사슬을 갖는 폴리올에스터 오일의 마모특성(I))

  • 한두희;마사부미마스꼬
    • Tribology and Lubricants
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    • v.17 no.2
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    • pp.109-115
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    • 2001
  • The lubricating performance of 23 kinds of polyol ester base oils 〔POEs〕 having different branch shapes was investigated by using a four ball tribometer under boundary lubrication condition. All the polyol ester base oils used in this study were made up of polyhydric alcohols of two-four valence and normal or branched fatty acids of different carbon number. The wear characteristics of polyol ester base oils are different from those of mineral oil, strongly affected by the branch shapes of fatty acids in their molecles. In particular, the polyol ester base oils having normal fatty acids such as n-octanoic acid, n-nonanoic acid etc. show much better wear performance than POEs having branched fatty acids such as 2-ethylhexanoic acid, 3,5,5-trimethyl hexanoic acid, etc. As the carbon chain length of normal fatty acids, in case of POEs of normal fatty acids, is increased, their wear rate is decreased and, in case of POEs of branched fatty acids, as the degree of branch of branched fatty acids is decreased, their wear rate is decreased. All the wear results of polyol ester base oils could be reasonably explained by comparing cohesive ability among fatty acid molecules in adsorption film by fatty acids obtained as POEs were decomposed.

Partially Folded States of Mutant Ubiquitin in Mild Denaturing Conditions

  • Park, Soon-Ho
    • Bulletin of the Korean Chemical Society
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    • v.30 no.7
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    • pp.1567-1572
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    • 2009
  • Conformational change of ubiquitin variant with valine to alanine mutation at sequence position 26 was studied by varying solvent pH. Fluorescence emission spectra indicated that this variant ubiquitin has some residual structures in acidic and basic solution as compared to denaturant-induced unfolded state. Far-UV circular dichroic spectra indicated that the base-denatured state had more secondary structure than the acid-denatured state. Near-UV circular dichroic spectra indicated that the aromatic side-chains were in the relatively more rigid environment in the base-denatured state than those in the acid-denatured state. Although it appears that the more tertiary structure present in the base-denatured state, refolding reactions measured by stopped-flow fluorescence device suggest that both the acid- and base-denatured states occur before the major folding transition state. The acid- and base-denatured states are considered to reflect the early event of protein folding process.

A Study on Characteristics of Acid-Base Balance in Goats (염소의 산·염기 균형 특성에 관한 연구)

  • Yang, Il-suk;Sung, Ho-kyng
    • Korean Journal of Veterinary Research
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    • v.25 no.2
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    • pp.133-144
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    • 1985
  • The changes of acid-base status in vitro of the venous blood for 24 hours in ten Korean native goat were investigated. The acid-base parameters were measured within ten minutes after collection of the blood, and every hour during the first six hours and finally after twenty four hours of storage. Blood samples were stored at two different temperatures ($0-4^{\circ}C$ and $21-24^{\circ}C$). Twelve goats were induced acute acid-base disturbances by intravenous infusion of either hydrochloric acid or sodium bicarbonate and inhalated with $CO_2$ gas mixture (20% $CO_2$, 80% $O_2$) or hyperventilation were performed by means of respirator. The results were as follows; 1. Blood samples could be stored during the first two hours in ice water ($0-4^{\circ}C$) and one hour at room temperature without significant changes in pH. The magnitudes of changes were similar to those of cow, and lower than those of men and dogs. 2. The mean values of acid-base parameters in normal goat were arterial pH, 7.40; $P_{CO_2}$, 35.4mmHg; $HCO_3{^-}$, 21.8mEq/L. 3. Both the base excess and the bicarbonate showed high correlation (r=0.99) during the metabolic disturbance and were represented as $B.E.=1.38\;HCO^-{_3}-29.7$. 4. The slope of blood buffer curve obtained from the in vivo experiment was 16.3mEq/L/pH. 5. The magnitudes of changes in hydrogen ion concentration per unit change of $P_{CO_2}$ were 0.8nM/mmHg in hypercapnia and 1.0nM/mmHg in hypocapnia. 6. The ranges of acid-base parameters in normal goat urine were pH, 6.0-8.1; $P_{CO_2}$, 42-61mmHg; $HCO_3{^-}$, 2-110mEq/L. The concentration of potassium was higher (60-200mEq/L), and that of sodium was lower (8-70mEq/L) than those of human urine.

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