• Metals and materials international
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• 제24권6호
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• pp.1386-1393
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• 2018

The solubility of $TiO_2$ in $NaF-CaF_2-BaF_2$ ternary eutectic melts was investigated at the temperature range of $1025-1150^{\circ}C$. The least-squares equation was obtained from the relationship between the reciprocal temperature and the natural logarithm of the titanium concentration in the melts saturated with $TiO_2$. The corresponding partial molar enthalpy of dissolution of $TiO_2$ was found to be 188 kJ/mol. The titanium saturation concentration was 3.73 wt% at $1100^{\circ}C$. From the titanium concentration change with the added amount of $TiO_2$ at different holding time after a final stirring, it was found that not only complete dissolution of $TiO_2$ but also enough sedimentation of excessive $TiO_2$ should be guaranteed to obtain more reliable solubility data. The holding time of 10 h was found to be enough for the excessive $TiO_2$ particles to settle down in our experimental conditions. It is noteworthy that in case of adding $TiO_2$ in excess of its solubility, the $Ba_{1.12}(Ti_8O_{16})$ phase was observed at the lower and bottom of the solidified salt ingots.

• Journal of Magnetics
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• 제14권2호
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• pp.80-85
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• 2009

The mineral dissolution sensor system using GMR-SV and glass/Mg(200 nm) was prepared and characterized. The magnetic field sensitivity of GMR-SV to microscopic magnetic variation was about 0.8%/Oe. The change that occurs when Mg-film dissolves in water, the solubility of water, which is one of the basic properties of mineral water, was sensed by measuring the subtle variation of an electric current. In the case of edible water with Mg mineral added, bubbles were generated on the surface of the Mg film in the first 45 minutes, and the number of drops that were dissolved more rapidly than with the tap and DI waters later reduced to zero. For the edible water samples that each had different mineral Mg concentrations, the Mg solubility speed significantly differed. After injecting Mg film into the edible water, the magnetoresistance of the output GMR-SV signal decreased from a maximum of $45.4\;{\Omega}$ to a minimum of $43.6\;{\Omega}$. The measurement time was within 1 min, giving the rate of change ${\Delta}R/{\Delta}t=0.18\;{\Omega}/s$. This measurement system can be applied to develop a mineral Mg solubility GMR-SV sensor that can be used to sense the change from edible water to reduced alkali.

• Restorative Dentistry and Endodontics
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• 제35권5호
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• pp.344-352
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• 2010

연구목적: 본 연구의 목적은 glass ionomer cement (GIC)와 혼합한 mineral trioxide aggregate (MTA)의 경화 시간, 압축 강도, 용해도, pH를 평가하고 이것을 MTA, GIC, IRM, SuperEBA와 비교하는 것이다. 연구 재료 및 방법: 경화 시간과 압축 강도는 ISO 9917, 그리고 용해도는 ISO 6876 기준에 따라 측정하였다. pH는 고체시편 전용 전극이 연결된 pH meter를 이용하여 측정하였다. 결과: GIC와 혼합한 MTA의 경화시간은 MTA보다 유의하게 짧았으며 압축 강도는 7일간 모든 시점에서 다른 재료보다 유의하게 낮았다. GIC와 혼합한 MTA 중에서 1 : 1과 2 : 1 시편의 용해도는 다른 실험군보다 유의하게 높았다. 또한 GIC와 혼합한 MTA의 pH는 혼합직후 2-4의 범위에서 1일 후 5-7 사이로 증가하였다. 결론: GIC와 혼합한 MTA의 경화시간은 MTA에 비해 개선되었으나 압축강도 및 pH와 같은 다른 성질들은 MTA에 비해 오히려 열등한 것으로 밝혀졌다. 임상적 사용이 가능하려면, MTA의 기존 장점을 저해하지 않으면서 단점을 개선하기 위한 적절한 혼합비를 찾아내고 생체친화성을 평가하는 추가적인 연구가 필수적이다.

• 한국지구과학회지
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• 제25권1호
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• pp.39-47
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• 2004

In the FMAS system the effect of iron on alumina solubility in orthopyroxene has been determined by experiments with crystalline starting mixtures of garnet and orthopyroxene of known initial compositions at 20 kb, 975$^{\circ}C$ and 25 kb, 1,200$^{\circ}C$. These data have been modeled to develop a thermodynamic method for the calculation of Al$_{2}$O$_{3}$ in orthopyroxene as a function of P, T and composition. The direct application of the alumina solubility data in the MAS system to natural assemblages could lead to significant overestimation of pressure, probably by about 5kb for the relatively common garnet-lherzolites with abot 25 mol per cent Ca + Fe$^{2+}$ in garnet and about 1 wt. per cent Al$_{2}$O$_{3}$ in orthopyroxene since the effect of Fe is similar to that of Ca and Cr$^{3+}$in reducing the alumina solubility in orthopyroxene in equilibrum with garnet relative to that in the MAS system.

• Asian-Australasian Journal of Animal Sciences
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• 제12권8호
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• pp.1277-1284
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• 1999

Eight feeds and their residues left after washing with tap water (water residue) or incubation in the rumen (rumen residues) were treated with hydrochloric acid, neutral detergent solution without EDTA (NDS) or both, and the release or sorption of minerals (Ca, Mg, P, Na, K, Cu and Zn) assessed. Six of the feeds were from Sri Lanka (Panicum maximum ecotype Guinea A, Glyricidia maculate, Artocarpus heterophyllus (jak leaves), untreated and urea-treated rice straw, and rice bran) and two from the Netherlands (maize silage and wheat straw). The initial concentration of mineral elements, the concentration of neutral detergent fibre (NDF) and the type of feed significantly influenced (p<0.01). The proportion of the mineral elements released or sorbed. In general, feeds with high NDF content (straws and guinea grass) sorbed Ca from tap water, or released less in the rumen, and within these feeds the extent of sorption varied with source of fibre. Acid or NDS treatment removed little of the sorbed Ca, but they removed much of the Mg from both water and rumen residues. Fibres of wheat straw and jak leaves showed an affinity for Mg in the rumen. All feeds and their water and rumen residues sorbed P and Na from NDS, and the extent of sorption varied with the initial concentrations of these elements and with the type of fibre. Acid treatment removed part of the sorbed Na, but not the P. The solubility of K was not affected by the content of NDF, the type of fibre or the initial concentration of K. All feeds and their residues, except for the rumen residues of rice bran sorbed Cu from tap water and in the rumen. The recovery of Cu in rumen residues declined from 353% to 147% after NDS treatment, and with some feeds (glyricidia and jak leaves) the recovery was below 100%. Acid treatment removed part of the Zn sorbed by the water and rumen residues, but the capacity of residues to retain Zn varied with the type of feed.

• Asian-Australasian Journal of Animal Sciences
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• 제2권4호
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• pp.583-590
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• 1989

Increasing levels of ammonia-N in the rumen fluid used for in vitro incubation were achieved by supplementation of the ration of the donor cows with urea and by addition of urea either with or without glucose to the rumen fluid after collection. The ration of the donor animals consisted of wheat straw (80%) and maize silage (20%). During the second half of the experiment the basal ration was supplemented with a mineral mixture. Wheat straw, Guinea grass and two rice straw varieties were incubated with the various kinds of rumen fluid. Parameters studied were: solubility, apparent organic matter disappearance after 48 hours of incubation ($OMD_{48}$), rate of organic matter degradation from 0 to 24 hours of incubation ($k_1$) and from 24 to 95 hours ($k_2$). The concentration of ammonia-N in the rumen fluid at which 95% of the maximal $OMD_{48}$ and k1 were reached (88.2 and 100.0 mg/l) were independent of the feed. With regard to the $k_2$ the required ammonia-N concentration to reach 95% of the maximal $k_2$ differed per feed. Mineral supplementation increased the OMD48 and $k_1$, but not the solubility and $k_2$. Glucose addition in combination with urea had no beneficial effect compared to urea supplementation alone.

• 자원리싸이클링
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• 제29권4호
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• pp.58-66
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• 2020

나트륨 농축수로부터 나트륨 화합물을 합성하기 위하여 탄산화(step I) 및 저온 결정화(step II)를 수행하였다. 탄산화 과정에서는 반응 온도를 조절 변수로 이용하여 이를 통해 이산화탄소(95 wt.%)의 용해도 및 pH를 변화시켰다. 저온 결정화 과정은 탄산화 과정 후 2 ℃로 유지한 상태에서 진행하였다. 이산화탄소의 주입은 용액 내 탄산 이온의 안정적 생산과 포화 용해도를 고려하여 두 차례 주입하였다. 첫 번째 주입은 이산화탄소 주입량 증가 및 안정적인 탄산 이온 생성을 목적으로 반응 온도를 35 ℃에서 10 ℃로 변화시켜 CO₂의 용해도를 변화하고자 하였고, 두 번째 주입은 NaCl 용액 혼합과 동시에 탄산화를 통한 나트륨 화합물의 핵생성을 유도할 목적으로 수행하였다. 또한 저온 결정화에서는 pH 조절 및 반응 온도 변화(10 ℃에서 2 ℃)를 통해 탄산화 속도를 느리게 유도함으로써 나트륨 화합물의 결정 성장을 유도할 수 있었다. 본 연구에서는 NaOH 농도에 대한 효과를 검토하였으며 2M NaOH를 사용한 경우에 나트룸 화합물의 순도가 증가하였다. 또한, 합성 한 나트륨 화합물은 대부분 rod 형상을 갖는 물질들로 X-선 회절 분석을 통해 중탄산나트륨 또는 수화물(monohydrate) 형태의 탄산나트륨임을 확인하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제29권11호
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• pp.1608-1615
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• 2016

This study was conducted to determine the solubility of copper (Cu) in two sources of copper(II) sulfate ($CuSO_4$) including monohydrate and pentahydrate and three sources of dicopper chloride trihydroxide (dCCTH) including ${\alpha}$-form (dCCTH-${\alpha}$), ${\beta}$-form (dCCTH-${\beta}$), and a mixture of ${\alpha}$- and ${\beta}$-form (dCCTH-${\alpha}{\beta}$) at different pH and a 3-step in vitro digestion assay for pigs. In Exp. 1, Cu sources were incubated in water-based buffers at pH 2.0, 3.0, 4.8, and 6.8 for 4 h using a shaking incubator at $39^{\circ}C$. The $CuSO_4$ sources were completely dissolved within 15 min except at pH 6.8. The solubility of Cu in dCCTH-${\alpha}$ was greater (p<0.05) than dCCTH-${\beta}$ but was not different from dCCTH-${\alpha}{\beta}$ during 3-h incubation at pH 2.0 and during 2-h incubation at pH 3.0. At pH 4.8, there were no significant differences in solubility of Cu in dCCTH sources. Copper in dCCTH sources were non-soluble at pH 6.8. In Exp. 2, the solubility of Cu was determined during the 3-step in vitro digestion assay for pigs. All sources of Cu were completely dissolved in step 1 which simulated digestion in the stomach. In Exp. 3, the solubility of Cu in experimental diets including a control diet and diets containing 250 mg/kg of additional Cu from five Cu sources was determined during the in vitro digestion assay. The solubility of Cu in diets containing additional Cu sources were greater (p<0.05) than the control diet in step 1. In conclusion, the solubility of Cu was influenced by pH of digesta but was not different among sources based on the in vitro digestion assay.

• 자원리싸이클링
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• 제30권6호
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• pp.3-11
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• 2021

본 연구에서는 소듐바나데이트 수용액에 염화암모늄을 첨가하여 암모늄메타바나데이트를 침전시킬 때, 암모늄메타바나데이트의 용해도와 암모늄이온의 분해율이 침전반응에 미치는 영향을 알아보았다. 침전온도와 수용액 pH가 증가함에 따라 암모늄 이온의 분해율이 증가하였으며 45 ℃에서 수용액 pH 9.3일 때 분해율은 81% 이상으로 pH 8일 때와 비교하였을 때 약 4배 정도 증가하였다. 그러므로 침전 반응에 큰 영향을 미치는 침전온도와 수용액 pH 두 인자를 고려하여 침전반응을 수행한 결과, 침전온도가 증가함에 따라 침전속도가 증가하였으나 35 ℃ 이상에서는 침전온도의 영향이 크지 않았다. 침전반응 속도론적 고찰을 통하여 얻은 침전반응의 활성화 에너지는 42.3 kJ/mol이었다. 이와 같은 연구를 통하여 암모늄메타바나데이트의 용해도를 고려하였을 때 침전온도는 낮을수록 바나듐 회수율에 유리하였다. 또한 암모늄 이온의 분해를 고려하였을 때 수용액의 pH는 낮을수록 유리하나 pH 8 이하에서는 소듐폴리바나데이트가 침전되며 바나듐 산화물의 순도 저하가 야기될 수 있었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.253-260
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• 2002

Chemical weathering processes related with mineralogical characters and ground water condition are very essential engineering problems in soluble rock masses. Detailed geological mapping were performed and 8 samples were collected from the 2 formations including various rock faces to deduce the possibility of the limestone cavity formation and their mechanism. Petrological descriptions and various petro-mineralogical experiments such as XRD analysis, clay mineral analysis, absorptivity test, impurity analysis were conducted to evaluate the cavity making processes. Laboratory solubility test for rock specimen were also carried out under the strong acid (pH=1) condition. From the experimental data and geological mapping data, it is found that the formation of limestone cavities in limestones are strongly related with geological structures such as beddings, cleavages and the contents of impurities rather than CaCO$_3$contents. In case of dolomites, rock textures, grain size, amounts and types of clay minerals as well as geological structures are major controlling factors of cavity forming processes