• 약학회지
• /
• 제40권3호
• /
• pp.306-310
• /
• 1996

Five pseudopolymorphic modifications of cefazolin sodium were prepared by recrystallization. They were characterized by DSC and TGA. The solubilities of all modifications were c hecked through the dissolution test.

• 대한가정학회지
• /
• 제38권2호
• /
• pp.21-26
• /
• 2000

Effect of aluminum dissolution from aluminum sauce pans with the kind and concentration of acidity, boiling times and temperature of acidity solution, in new and old sauce pans, and aluminum content in typical food was investigated. As acetic acid concentration increases, aluminum content has increased. But malic acid and citric acid have suddenly increased until acidity concentration would be 0.4%. After that rapidly increasing is not shown. As boiling time and temperature of acidity solution increases, concentration of aluminum dissolved from aluminum sauce pan has increased. Concentration of aluminum by repeated use has increased only a slightly. But aluminum content has dissolved in large quantities from new pan rather than old pan.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제20권1호
• /
• pp.19-27
• /
• 2015

If $CO_2$ stored for geological sequestration escapes from deep formations and is introduced to shallow aquifers, it dissolves into groundwater, creates acidic environments, and enhance mineral dissolution from rocks and soils. Among these minerals, dissolution and spread of hazardous trace metals can cause environmental problems with detrimental impacts on groundwater quality. This study aims to investigate geochemical effects of $CO_2$ in groundwater on dissolution of galena, the main mineral controlling the mobility of lead. A series of batch experiments are performed with granulated galena in $CO_2$ solutions under various experimental conditions for $CO_2$ concentration and reaction temperature. Results show that dissolution of galena is significantly enhanced under acidic environments so that both of equilibrium concentrations and dissolution rates of lead increase. For thermodynamic analysis on galena dissolution, the apparent rate constants and the activation energy for galena dissolution are calculated by applying rate law to experimental results. The apparent rate constants are $6.71{\times}10^{-8}mol/l{\cdot}sec$ at $15^{\circ}C$, $1.77{\times}10^{-7}mol/l{\cdot}sec$ at $25^{\circ}C$, $3.97{\times}10^{-7}mol/l{\cdot}sec$ at $35^{\circ}C$ and the activation energy is 63.68 kJ/mol. The galena dissolution is suggested to be a chemically controlled surface reaction, and the rate determining step is the dissociation of Pb-S bond of surface complex.

• 대한화학회지
• /
• 제54권1호
• /
• pp.88-92
• /
• 2010

이소프로필 멀케푸탄은 중요한 약품 중간체이며 싸이오우레아와 트리글리콜은 이소프로필 멀케푸탄을 합성을 하는데 중요한 화합물이다. 그러므로 트리글리콜 용액에서의 싸이오우레아의 용해는 이소프로필 멀케푸탄의 생산에 중요하다. 트리글리콜용액에서 싸이오우레아의 용해 반응속도론을 조사하고 이소프로필 멀케푸탄을 생산하는 대체 공정을 제시하는것이 본 연구의 목적이다. 트리글리콜용액에서 싸이오우레아의 용해 반응속도론을 조사하기 위하여 용액 농도와 반응 온도를 중점적으로 관찰하였다. 싸이오우레아의 용해속도는 용액농도와 온도가 증가할수록 증가하였다.

• 자원리싸이클링
• /
• 제18권6호
• /
• pp.38-45
• /
• 2009

마그네사이트 광석의 염산용해 특성 및 불순물 제거에 대한 연구를 수행하였다. 마그네사이트의 용해율은 용해온도가 증가할수록, 광석 입도가 감소할수록 증가하였다. 최적 용해조건은 용해시간 2시간, 용해온도 $80^{\circ}C$, 광석입도 $100\;{\mu}m$ 였으며, 최적 용해조건에서 98%의 Mg를 용해할 수 있었다. Si, Al 성분들은 대부분 용해잔사에 존재하므로 용해 후 여과를 통하여 상당량 제거가 가능하였으며, 용해된 불순물들은 용액의 pH 조절을 통하여 금속 수산화물로 석출시켰다. 또한 석출된 금속 수산화물을 응집, 침강시키기 위하여 고분자 응집제를 사용하였으며, 최적 응집제 주입 조건은 비이온계 고분자 응집제 1 mg/100 ml이었다.

• Journal of Pharmaceutical Investigation
• /
• 제34권2호
• /
• pp.91-94
• /
• 2004

To develop a poloxamer-based solid suppository with poloxamer mixtures, the melting points of various formulations composed of P 124 and P 188 were investigated. To investigate the effect of poloxamer to the dissolution ad dissolution mechanism of diclofenac sodium from the suppository the dissolution of diclofenac sodium delivered by the poloxamer-based suppository was performed. Furthermore, to investigate the mucoadhesive property of the poloxamer-based sold suppository, the identification test in the rectum was carried out after its rectal administration in rats. The poloxamer mixtures composed of P 124 and P 188 were homogeneous. Ver small amounts of P 188 affected the melting points of poloxamer mixtures. In particular, the poloxamer mixture [P 124/P 188 (97/3%)] with the melting point of about $32^{\circ}C$ was a sold for at room temperature and instantly melted at physiological temperature. Furthermore, very small amounts of P 188 in the poloxamer-based suppository hardly affected the dissolution rates of diclofenac sodium from the suppository. Dissolution mechanism analysis showed the dissolution of diclofenac sodium was proportional to the time. At 4 h after administration, the blue colo of poloxamer-based suppository [diclofenac sodium/poloxamer mixture (2.5/97.5%)] with the P 124/ P 188 ratio of (97/3%) and blue lake in the rectum was faded. However, the position of suppository in the rectum did not significantly change with time. Thus, it retained in thε rectum for at least 4 h. Our results indicated that the poloxamer-based sold suppository with P 124 and P 188 would be a candidate of rectal dosage form for diclofenac sodium.

• 한국세라믹학회지
• /
• 제56권4호
• /
• pp.387-393
• /
• 2019

A N₂H₄-Cu(I)-HNO₃ solution was used to dissolve magnetite powders and a simulated oxide film on Inconel 600. The addition of Cu(I) ions to N₂H₄-HNO₃ increased the dissolution rate of magnetite, and the reaction rate was found to depend on the solution pH, temperature, and [N₂H₄]. The dissolution of magnetite in the N₂H₄-Cu(I)-HNO₃ solution followed the contracting core law. This suggests that the complexes of [Cu⁺(N₂H₄)] formed in the solution increased the dissolution rate. The dissolution reaction is explained by the complex formation, adsorption of the complexes onto the surface ferric ions of magnetite, and the effective electron transfer from the complexes to ferric ions. The oxide film formed on Inconel 600 is satisfactorily dissolved through the successive iteration of oxidation and reductive dissolution steps.

• 한국세라믹학회지
• /
• 제37권3호
• /
• pp.271-279
• /
• 2000

5 m/o Yb-doped SrCeO3 proton conductor was prepared by a solid state reaction method and its total electriccal conductivity measured as a function of both oxygen partial pressure and water vapor partial pressure in the temperature range of 500~100$0^{\circ}C$. From the total conductivity have been deconvoluted the partial conductivities of oxide ions, protons, and holes, respectively, on the basis of the defect model proposed. The equilibrium constant of hydrogen-dissolution reaction, proton concentration, and mobilities of oxygen vacancies and protons have subsequently been evaluated. It is verified that SrCe1-xYbxO3 is a mixed conductor of holes, protons and oxide ions and the proton conduction prevails as temperature decreases and water vapor pressure increases. The heat of water dissolution takes a representative value of $\Delta$HoH=-(140$\pm$20) kJ/mol-H2O, but tends to be less negative with increasing temperature. Migration enthalpies of proton and oxygen vacancy are extracted as 0.83$\pm$0.10 eV and 0.81$\pm$0.01 eV, respectively.

• 열처리공학회지
• /
• 제35권1호
• /
• pp.1-7
• /
• 2022

In this study, dissolution and melting phenomenon of the Al₂Cu was studied for the high-strength Al-Si-Cu aluminum alloy in automobile component. The Solution heat treatment was performed at 480℃ and 510℃ for 4hours. Microstructure analysis of the specimen was performed using the optical micrograph and scanning electron microscope for qualitative and quantitative analysis of various phases, the chemical composition of secondary phases was achieved by energy dispersive spectroscopy (EDS) and electron probe micro analysis (EPMA). As a result of the electron probe micro analysis, a plate like Al₂Cu phase was observed, and eutectic Si phase was observed of a coarsen plate shape. At a temperature of 510, necking phenomenon occurs in a specific part of plate like Al₂Cu, and it is segmented and dissolved in the Al matrix. When the temperature of the alloy exceeds the melting point of Al₂Cu, incipient melting occurs at the grain boundary of undissolved Cu particles

• 신재생에너지
• /
• 제4권2호
• /
• pp.12-20
• /
• 2008

Calculations for the dissolution behavior of liquid CO2 droplets released in the East Sea and the Clipperton Clarion from a moving ship and a fixed pipeline have been carried out in order to estimate the CO2 dissolution characteristics in the ocean. The results show that the injection of liquid CO2 from a moving ship in a high temperature point is an effective method for dissolution. Also, it is noted that the ultimate plume generated from CO2 bubbles repeatsand shrinking due to the peeling from a fixed pipeline, and the presence of hydrate layer on a liquid CO2 droplet acts as a resistant layer in dissolving liquid CO2.