• Proceedings of the Safety Management and Science Conference
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• 2011.04a
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• pp.553-557
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• 2011

• Journal of the Korean Applied Science and Technology
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• v.26 no.4
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• pp.385-393
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• 2009

Different types magnesium hydroxide groups have been obtained using the hydrothermal precipitation technique from magnesium sulfate and calcium carbonate solution. The Mg atom coordinated around O atom of ${SO_4}^{2-}$ in another layer to form a multi-layer structure crystal. The influence of synthesis parameters on the morphological characteristics and size of magnesium hydroxide groups precipitated in aqueous were investigated such as different of additive and pH. Magnesium hydroxide groups were decomposed gradually and converted finally to MgO particles after heated in air temperature up to $1050^{\circ}C$. The particle size and it's distribution morphology, crystal phase and thermal behavior of the samples were characterized through XRD, SEM, EDS, and TG/DTA.

• Journal of the Korean Ceramic Society
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• v.53 no.1
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• pp.7-12
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• 2016

In this paper, we have developed a simple, new and economical carbonation method to synthesize a pure form of aragonite needles using dolomite raw materials. The obtained aragonite Precipitated Calcium Carbonate (PCC) was characterized by XRD and SEM, for the measurement of morphology, particle size, and aspect ratio (ratio of length to diameter of the particles). The synthesis of aragonite PCC involves two steps. At first, after calcinated dolomite fine powder was dissolved in water for hydration, the hydrated solution was mixed with aqueous solution of magnesium chloride at $80^{\circ}C$, and then $CO_2$ was bubbled into the suspension for 3 h to produce aragonite PCC. Finally, aragonite type precipitated calcium carbonate can be synthesized from natural dolomite via a simple carbonation process, yielding product with average particle size of $30-40{\mu}m$.

• YAKHAK HOEJI
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• v.31 no.1
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• pp.14-18
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• 1987

2-Substituted-3, 4-dihydro-2H-1, 2-benzothiazin-4-one 1, 1-dioxide 6 was reatced with magnesium methyl carbonate to form magnesium chelate 7, which could be hydrolized in cold hydrochloric acid solution to give 2-substituted-4-hydroxy-2H, 1, 2-benzothiazine-3-Carboxylic acid 1, 1-dioxide 2 in good yield.

• Magazine of the Korean Society of Agricultural Engineers
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• v.27 no.2
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• pp.57-71
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• 1985

The characteristics of compaction and unconfined compressive strength were investigated by mixing with lime to all soils adjusted by given percentages of two kinds of clays to sand to obtain the most effective distribution of grain size and the optimum lime content for soil stabilization. In addition, unconfined compressive strength and durability tested by adding of sodium metasilicate, sodium sulfate, sodium carbonate, sodium gydroxide and magnesium oxide to lime-soil mixture mixed with 8 percent lime to adjusted soil having the mixing percentage of 60 percent of cohesive black clay and 40 percent of sand by weight to get the effect and the optimum content of chemicals. The results obtained were as follows; 1.With the addition of more lime, the optimum moisture content was increased, and the maximum dry density was decreased, whereas the more the amount of clay and the less was the maximum drt density. 2. In the soil having more fine grain size the unconfined compressive strength was larger in the earlier stage of curing period, in accordance with the longer period, the mixing percentages of sand to clay showing the maximum unconfined compressive strength, on the basis of 28-day strength, were 60% : 40% (black clay) and 40% : 60% (brown clay) respectively. 3. The reason why the soil adjusted with black clay was remarkably bigger in the unconfined compressive strength than ones adjusted with brown clay for all specimen of lime-soil mixture was the difference in the kind of clay, the amount of chemical compositions the value of pH. Black clay was mainly composed of halloysite that reacted with lime satisfactorily, whereas the main composition of brown clay was kaolinite that was less effect in the enhance of unconfined compressive strength. Also the difference of unconfined compressive strength was because black clay was larger in the amount of composition of calcium oxide and magnesium oxide in the value of pH affecting directly on the unconfined compressive strength of lime-soil mixture than brown clay. 4. In the lime-soil mixture mixed with 8 percent of lime to soil that mixing percentage of sand to black clay was 60% : 40%, on the standard of 7-day strength, the effect of chemical was arranged in the order of magnesium oxide, sodium carbonate, sodium sulfate, sodium hydroxide and sodium metasilicate. 5. The optimum amount of chemical being applicable to the maximum unconfined compressive strength of lime-chemical-soil mixture was 1 percent by weight for air dry soil in the case of adding sodium carbonated and 0.75 percent on sodium hydroxide, the unconfined compressive strength was increased continuously with increase of the amount of chemical up to 2 percent of chemical content is the lime-chemical-soil mixture added sodium metasilicate, sodium sulfate and magnesium oxide. 6. It was considered that the chemical played and accelerant role of early revelation of strength because the rate of increase of unconfined compressive strength of all of lime-chemical-soil mixtures was largest on the 7-day cured specimen. 7. The effect of test on freezing and thawing after adding suitable amount of chemical on the lime-soil mixture mixed with 8 percent of lime to soil that mixing percentage of sand to black clay was 60% : 40% was arranged in the order of magnesium oxide, sodium carbonate, sodium sulfate, sodium metasilicate and sodium hydroxide.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.2
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• pp.290-296
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• 2003

Tsaiya ducks and Leghorn hens are the two major laying birds raised in Taiwan. They are all excellent egg layers. Tsaiya ducks are small in body size (1.3 kg) with bigger egg weight (65 g) and stronger eggshell breaking strength than eggs from hens. The eggshell consists mainly of calcium carbonate, hence calcium plays an important role in the eggshell formation. Magnesium is also present in eggshell in small amounts, which may have effect on maintaining eggshell quality. In comparison studies, it was shown that the duck eggshells contained higher calcium and lower magnesium content than chicken eggshells. The eggshell magnesium content was not affected by the dietary magnesium levels (690-2380 ppm) in ducks, but in hens, it increased linearly with dietary magnesium levels. The palisade layer ($5000{\times}$) of the eggshell was found to have a compact form for ducks while there are many hallow vesicles in chicken eggshells. The eggshell magnesium deposition model is different for ducks and hens with ducks having a one-peak and hens having a two-peak model. The calcium deposition model is similar for both birds. Both the carbonic anhydrase specific activity and total activity in the shell gland mucosa of ducks are higher than those in hens. Ducks retain higher magnesium and lower calcium in the shell gland mucosa and secret less magnesium and more calcium into the shell gland lumen for eggshell deposition. The ATPase specific activity is maintained fairly constant during the eggshell forming stage, indicating continuous calcium transport into the shell gland lumen for eggshell formation. The magnesium content in duck eggshells is much lower than that in hens indicating that the magnesium content in the eggshell may have an effect on eggshell quality.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.908-912
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• 2012

Lauan sawdust was gasified by steam reforming for hydrogen production from biomass waste. The fixed bed gasification reactor with 1m height and 10.2 cm diameter was utilized for the analysis of temperature and catalysts effect. Steam was injected to the gasification reactor for the steam reforming effect. Lauan sawdust was mixed with potassium carbonate, sodium carbonate, calcium carbonate, sodium carbonate + potassium carbonate and magnesium carbonate + calcium carbonate catalysts of constant mass fraction of 8:2 which was injected to the fixed gasification equipment. The compositions of production gas of gasification reaction were analyzed at the temperature range from $400^{\circ}C$ to $700^{\circ}C$. Fractions of hydrogen, methane and carbon monoxide gas in the production gas increased when catalysts were used. Fractions of hydrogen, methane and carbon monoxide gas were increased with increasing temperature. The highest hydrogen yield was obtained with sodium carbonate catalyst.

• International Journal of Industrial Entomology and Biomaterials
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• v.25 no.1
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• pp.123-127
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• 2012

An experiment was carried out to boost the production of tasar crops through application of secondary nutrients. Different combinations of secondary nutrients were prepared and its effect was studied on the yield and quality of leaves of tasar food plant Terminalia tomentosa W & A with 2.4 m ${\times}$ 2.4 m spacing and cocoon characters of tasar silkworm Antheraea mylitta Drury reared on them. Among different combinations of secondary nutrients, foliar application of magnesium sulphate (2%, w/v) and basal application of 3 quintal/ha of calcium carbonate (secondary nutrient combination SM5) was found to be the best in crop improvement. It improves the quantity and quality of leaves as well as the commercial characters of cocoons. As a result, silk production improves. Under this combination, leaf yield increased by 26.55% in comparison to control. Average increase in moisture, total mineral, crude protein and total carbohydrate was 3.26%, 20.84%, 15.39% and 17.85% respectively as compared with control. Further, bio assay studies revealed that average larval weight, E.R.R., cocoon weight, shell weight and silk ratio percent increased by 11.25%, 25.71%, 20.05%, 35.14% and 12.17% respectively over control which indicates that secondary nutrient combination $SM_5$ has significant role in improving the production of tasar crops.

• Korean Journal of Materials Research
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• v.26 no.7
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• pp.359-362
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• 2016

Mineral filler is used for resin compounds, because it increases the stiffness and thermal stability of a resin compound, and it also cuts down the cost. Calcium carbonate, silica, magnesium oxide, and others are used as filler materials in general, and the type of filler material, the size, and content can affect the physical properties of compounds. Those factors also influence the viscosity of resin mixtures and the workability, and should be adjusted by changing the contents of the filler, which depends on the size. In this study, five kinds of ground calcium carbonate, which were different in size, were used to produce polyester compounds ; the physical properties were compared with the filler size and contents. The mechanical properties were measured by bending strength and tensile strength, and the heat deflection temperature was obtained for thermal stability.

• Journal of the Korean Ceramic Society
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• v.20 no.2
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• pp.99-106
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• 1983

This experiment has been carried out for the purpose of investigating the effect of $Ga_2O_3$ and $GeO_2$ additivies on sintering of magnesium oxide over the temperature range of 130$0^{\circ}C$~150$0^{\circ}C$. The effect of calcining temperature on the bulk densities of fired compacts prepared from this material was observed MgO powder has been obtained by calcining extra reagent grade magnesium carbonate(basic fired) at 90$0^{\circ}C$ for 30 minutes $Ga_2O_3$and GeO2 were added in the ratio of 1, 2, and 3 wt% to MgO and mixed with calcined MgO. The specimens were prepared by compression with pressure of $700kg/cm^2$ than fired at 130$0^{\circ}C$~150$0^{\circ}C$ for 0-5hrs. Sintering behaviour and microstructure of the fired specimens were examined. The optimum calcination temperature of magnesium carbonate was 90$0^{\circ}C$. Densification rates obeyed the equation D=K in t+c. Theoretical density in the case of addition of $Ga_2O_3$ was 23.1 kcal/mole in the case of the additive $GeO_2$ was 14.176kcal/mole. This low value would appear to support a machanism of grain boundatry diffusion The range of average grain size in the case of addition of $Ga_2O_3$ and $GeO_2$ was 21$\mu\textrm{m}$-31$\mu\textrm{m}$.