• Title/Summary/Keyword: C-S-H 겔

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The Effect of Electrochemical Treatment in Lowering Alkali Leaching from Cement Paste to an Aquatic Environment: Part 2- Microscopic Observation (전기화학적 기법을 통한 시멘트페이스트의 수중노출에 따른 알칼리이온 침출저감 효과: Part 2- 미세구조 분석)

  • Bum-Hee Youn;Ki-Yong Ann
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.11 no.2
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    • pp.145-152
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    • 2023
  • In this study, microscopic observation was made on the surface of cement paste immersed in an aquatic environment for 100 days at electrochemical treatment to mitigate the leaching of alkali ions. To quantitatively rank the hydration products, unhydrated grains and porosity in the interfacial region, the backscattered electron(BSE) images were obtained by scanninng electron microscopy. As a result, it was found that the porosity on the surface was significantly reduced by the electrochemical treatment, while unhydrated grains were more or less increased presumably limited hydration reaction under electric charge. At electrochemical treatment, Ca2+ ions present in C-S-H gel could be precipitated with OH- to form Ca(OH)2 then to lower C-S-H gel and simultaneously to enhance Ca(OH)2. Substantially, the risk of alkali leaching could be lowered by the limited ionized matrix under electrochemical treatment.

Total Free SH Groups, Half Cystine and S-S Bond Contents of $\alpha$-Lactalbumin Gels by Various Additives (첨가물질에 따른 알파-락트알부민 겔의 총 유리 SH 그룹, Half-Cystine 및 S-S 결합 함량)

  • 박인덕;홍윤호
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.25 no.6
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    • pp.922-927
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    • 1996
  • In order to investigate heat-induced gelation properties of $\alpha-lactalbumin(\alpha-La),$ total free SH groups, half-cystine, and disulfide bond contents of $\alpha-La$ gels prepared in 0.1M Tris-HCI buffer(pH 8.0) were measured. The samples were heated at $90^{\circ}C$ for 40 minutes under different PH and concentrations of NaCl, $CaCl_2,$ $\alpha-La,$ N-ethylrnaleirnide(NEM), and dithiothreitol(DTT). Total free SH groups were low at high concentrations of $\alpha-La$ and at pH 6.5~8.5, and were $14.72~18.58\mu\textrm{m}ol/g$ and $14.17~16.11\mu\textrm{m}ol/g,$ respectively. Half-cystine contents of NEM-induced gels decreased with increasing concentration of NEM, and were $1.03~39.17\mu\textrm{m}ol/g.$ Disulfide bonds of DTT-induced gels increased with increasing concentration of DTT, and were $70.04~71.80\mu\textrm{m}ol/g$.

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PREPARATION AND PROPERTIES OF EIECTROCHROMIC WINDOW COATING BY THE SOL-GEL METHOD (졸-겔 방법에 의한 전기적 착색 박막의 제작과 특성)

  • Lee, Kil-Dong
    • Solar Energy
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    • v.12 no.2
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    • pp.18-27
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    • 1992
  • Multilayer coatings of $WO_3$ were deposited by the sol-gel technique on microscope slide glass and ITO coated glass. These films were characterized optically, chemically, and structurally by XRD, spectro-photometry, DTA/TGA, SEM/EDAX and RBS. Uniform $WO_3$ sol-gel films were dip coated on slide glass at dipping speed of 5mm/s. This sample indicated a low near IR transmittance in optical properties as a result of coloration using a dilute HCI electrolyte as the $H^+$ion sources. Differential thermal analysis results have allowed the accurate determination of the formation temperature of the $WO_3$ crystalline phase from the gel data in the range of $380^{\circ}C{\sim}500^{\circ}C$, consistent with crystallization temperature of sol-gel film. RBS spectrometry was performed on the uncolored $WO_3$ sol-gel film, yielding a chemical composition of $WO_3$.

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Gelation of Rapeseed Protein Induced with Microbial Transglutaminase (미생물성 Transglutaminase에 의한 유채단백질의 겔화)

  • Hyun, Eun-Hee;Kang, Yeung-Joo
    • Korean Journal of Food Science and Technology
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    • v.31 no.5
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    • pp.1262-1267
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    • 1999
  • Optimum reaction conditions for gel formation of rapeseed, Brassica napus, protein catalyzed by microbial TGase(transglutaminase) were evaluated by measuring breaking strength and deformation of gel. The polymerization of the protein gel was ascertained by SDS-PAGE and content of GL crosslinking$[{\varepsilon}-({\gamma}-glutamyl)lysine]$. In the reaction between rapeseed protein and TGase at $45^{\circ}C$ for 60 min, the breaking strength and deformation of the gel was the maximum at the ratio of 1 : 40 of enzyme to substrate. 10%(w/v) of rapeseed protein concentrate was optimum for gel production. The maximum breaking strength and deformation was shown at $45^{\circ}C$ The breaking strength increased linearly up to 90 min of the reaction time and remained unchanged. The breaking strength and deformation by TGase treatment was pH dependent and pH 7 was optimum for 10% rapeseed protein solution. SDS-PAGE analysis indicated that new band of highmolecular polymers were formed by the enzyme reaction, with disappearing the original bands of rapeseed protein. According to HPLC analysis. the content of GL crosslinking was increased from 0 to $7.14\;{\mu}mol/g$ gel for 90 min of the reaction time.

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Optimization of Culture Condition of Gluconacetobacter hansenii TF-2 for Cellulose Gel Production (Gluconacetobacter hansenii TF-2를 이용한 감귤과즙으로부터의 셀루로스 겔 생산의 최적화)

  • 최경호;정지숙;문철호;김미림
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.33 no.1
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    • pp.176-181
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    • 2004
  • Gluconacetobacter hansenii TF-2, an isolate from black tea fungus, was statically cultivated to ferment cellulose gel from citrus juice. The juice prepared by press filtering of peeled citrus fruit contained 135.5 mg of total sugar/mL, 1.23% of total acid, and average pH of the juice was 3.98. The bacterium produced cellulose gel optimally on the surface of culture broth containing 17% of citrus juice and 10$^{\circ}$Brix of total sugar. The optimum temperature was 3$0^{\circ}C$ for producing acetic acid and gel formation. The bacterium could not produce acetic acid on gel formation at 4$0^{\circ}C$. The optimum pH was 3.0∼4.0 but was not significantly different between pH 3.0∼4.0. The cultivation for 18 days under optimal conditions produced gel as 14.2$\pm$0.6 mm of thickness and acids equivalent to 1.90$\pm$0.22% of acetic acid. The pH of culture broth was stabilized at 2.6∼2.8 during the cultivation. Remaining sugar content was 27.1$\pm$4.2 mg/mL of total sugar and 6.9 mg/mL of reducing sugar. The gel productivity was 137.8$\pm$9.7 g/L.

Synthesis and Characterization of Comb-Type Grafted Polymer Hydrogels with Low Temperature Sensitivity (저온 감열 특성을 가지는 Comb-Type Grafted Polymer Hydrogels의 합성 및 특성평가)

  • Taek Kyu Jung;Sung Soo Kim;Byung Cheol Shin
    • Journal of the Korean Chemical Society
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    • v.47 no.1
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    • pp.59-66
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    • 2003
  • The comb-type grafted polymer hydrogels, which composed of N-isopropylacrylamide monomer and oligo(N-isopropylacrylamide-co-tert-butylacrylamide) [oligo(NIPAAm-co-t-BAM)], were synthesized by redox polymerization in 5~10% methanol aqueous solution using ammonium peroxodisulfate (APS) at 4 oC for 24h. The lower critical solution temperatures (LCSTs) of the comb-type grafted hydrogels were decreased with increase of t-BAM content in the grafted copolymer. We observed the effect of crosslinker and concentration of oligo(NIPAAm-co-t-BAM) on the shrinking/swelling ratio of hydrogels. Changes of shrinking/swelling ratio were decreased with increase of concentration of crosslinker. The increase of grafted oligo(NIPAAm-co-t-BAM) in the hydrogel shows an fast changes of shrinking/ swelling rate. The comb-type grafted hydrogels are expected to be valuable for the sensing materials of time-temperature labels(TTLs).

Magnetic Characteristics of BaFe12-2xCoxTixO19 Particles Prepared by Sol-gel Synthesis (졸-겔 합성에 의한 BaFe12-2xCoxTixO19 미립자의 자기적 특성)

  • 최현승;정지형;박효열;김태옥
    • Journal of the Korean Ceramic Society
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    • v.40 no.1
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    • pp.62-68
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    • 2003
  • Ba-ferrite particles added with Co and Ti, which were known well the additives for the control in coercivity, were synthesized by sol-gel method. In the range 90 to 120 minute reaction time, a stable sol solution which showed no change with temperature, pH, viscosity and aging time. After dried and heat treatment of sol solution, Ba-ferrite phase formed at $700^{\circ}C$ with Differential Thermal Analysis(DTA) and X-Ray Diffractometer(XRD) measurement. The crystallinity became to be better with increasing the temperature. It were showed by Scanning Electron Microscopy(SEM) that Ba-ferrite increased to particle sizes as increasing heating temperature and obtained of narrow particles size distribution. Also, magnetic characteristics of Ba-ferrite powders Co and Ti added were observed by a Vibrating Sample Magnetometer(VSM). Saturation magnetization$(M_s)$ was not much changed, however. the coercivity$(H_c)$dramatically dropped with addition of Co and Ti.

Development of Fly Ash/slag Cement Using Alkali-activated Reaction(2) - Reaction products and microstructure - (알칼리 활성반응을 이용한 플라이 애쉬/슬래그 시멘트 개발(2) - 반응생성물과 미세구조 -)

  • Park, Sang-Sook;Kang, Hwa-Young;Han, Kwan-Su
    • Journal of Korean Society of Environmental Engineers
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    • v.29 no.7
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    • pp.810-819
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    • 2007
  • Investigation of alkali activation of fly ash and blast furnace slag was carried out using waterglass and sodium hydroxide. XRD, FTIR, $^{29}Si$ and $^{27}Al$ NMR, TGA and SEM were used to observed the reaction products and microstructure of the fly ash/slag cement (FSC) pastes. The reaction products were amorphous or low-ordered calcium silicate hydrate and aluminosilicate gel produced from alkali activation of blast furnace slag and fly ash, respectively. On the basis of this investigation, waterglass solution with a modulus(Ms) of 1.0 and 1.2 is recommended for alkali activation of fly ash and blast furnace slag. Morphology of FSC pastes alkali-activated with Ms of 1.0 and 1.2 shows a more solid and continuous matrix due to restructuring of gel-like reaction products from alkali-activated fly ash and blast furnace slag together with another hydrolysis product(i.e., silica gel) from water glass.

Preparation and Characterization of BaTiO3 Powders and Thin films (티탄산바륨 분말과 박막의 제조 및 특성 연구)

  • Jung, Miewon;Son, Hyunjin;Lee, Jiyun;Kim, Hyunjung
    • Analytical Science and Technology
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    • v.17 no.2
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    • pp.173-179
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    • 2004
  • The $BaTiO_3$ powders and thin films were prepared by an alkoxide modified sol-gel process (polymerization-complex route) using ethylene glycol. The stable starting (Ba-Ti)-mixed metal organic sol was made by addition of acetylacetone. The $BaTiO_3$ powders, which had a particle size of 40~77 nm, were crystallized from an amorphous to a tetragonal phase on annealing at 700 and $1100^{\circ}C$ for 1 h. From FT-IR, solid-state $^{13}C$ CP/MAS NMR spectroscopy and X-ray diffractometry, the trace of the Ba-Ti-oxycarbonate phase first appeared at $400^{\circ}C$. Hydrolyzed sol was spin coated on a quartz wafer at 3500 rpm for 60 s and pyrolyzed at $1100^{\circ}C$ for 1 h. After heat treatment, the coated layer became dense and smooth.

Rheological Properties of Heat-Induced Gels of Surimi from Acid and Alkali Process (산 및 알칼리 공정으로 조제한 수리미 가열 겔의 물성 특성)

  • Choi Young Joon;Park Joo Dong;Kim Jin Soo;Cho Young Jae;Park Jae W.
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.35 no.4
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    • pp.309-314
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    • 2002
  • Rhtological properties of surimi gel from white fishes by acid (acid surimi) and alkali (alkali surmi) process and effect of chemicals on gelation were investigated by punch and dynamic tests. The breaking force and deformation values of heat-induced gel of acid surimi were less than their values of alkali and conventional surimi gel, and whiteness was greatly decreased, Gel point of acid surimi was decreased but it of alkali surimi was increased with increasing moisture content in the range of 80 to $85\%$. Storage modulus of acid surimi was the highest vaule in pH 6.8, but that of alkali surimi showed high value at neutral and slightly alkali pH. Propylene glycol increased storage modulus in $20\~50^{\circ}C$, hut urea and 2-mercaptoethanol suppressed it. Potassium bromide improved storage modulus in $20~80^{\circ}C$, The results suggest that alkai process is used for making surimi instead of conventional method.