• Korean Chemical Engineering Research
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• 제52권5호
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• pp.620-626
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• 2014

The main focus of this study was the evaluation of arsenic concentration in the ground water of Lahore at different depth and application of different mitigation techniques for arsenic removal. Twenty four hours of solar oxidation gives 90% of arsenic removal as compared to 8 hr. or 16 hr. Among oxides, calcium oxide gives 96% of As removal as compared to 93% by lanthanum oxide. Arsenic removal efficiency was up to 97% by ferric chloride, whereas 95% by alum. Activated alumina showed 99% removal as compared to 97% and 95% removal with bauxite and charcoal, respectively. Elemental analysis of adsorbents showed that the presence of phosphate and silica can cause a reduction of arsenic removal efficiency by activated alumina, bauxite and charcoal. This study has laid a foundation for further research on arsenic in the city of Lahore and has also provided suitable techniques for arsenic removal.

• 공업화학
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• 제7권2호
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• pp.245-251
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• 1996

일련의 $BeO-SiO_2$ 촉매를 염화베릴리움과 sodium silicate 혼합 용액을 공침전법으로 제조하였다. $SiO_2$에 BeO를 첨가하면 표면적, 산의 양, 산세기, 산촉매활성이 증가하여 BeO 함량이 20mol%일 때 최대를 나타내었다. X-선 회절로 조사한 결과 $400{\sim}500^{\circ}C$에서 소성된 촉매는 무정형으로 존재하였으며 $Br{\ddot{o}}nsted$ 산점과 Lewis 산점 모두를 가지고 있었다. Cumene의 dealkylation 반응에 대한 촉매활성은 촉매의 산의 양과 밀접한 관계를 가졌다.

• 한국세라믹학회지
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• 제14권4호
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• pp.230-235
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• 1977

In this paper the conditions of surface crystallization of glass were studied. The basic glass which is apt to crystallize, with $SiO_2$ 72.50, $Al_2O_3$ 5, 00, $Na_2O$ 8.00 $K_2O$ 3.50, CaO 5.00, MgO 3.00, $B_2O_3$ 3.00 Wt% is chosen. The strain point and softening point of this glass is 4$25^{\circ}C$ and 778$^{\circ}C$ each, and between the two temperatures we could get grystal on its surface by immersion in salt baths during some controlled hours. The kind of crystal on the surface of glass was confirmed by X-ray diffraction analysis and the change of the thickness of crystalline layers depending on temperature and time, was surveyed by using optical microscope. The results are as follows; 1. The chloride group is more suitable than sulfate group for the treating salt. 2. In the condition with 50 LiCl.50NaCl at 62$0^{\circ}C$ for 2 hrs and with 50 LiCL.20-30 NaCl.30-20 $CaCl_2$ at 72$0^{\circ}C$ for 15-20 min. we could get the best crystalline layers. 3. The crystal was silica-O and petalite with a little tridymite and nepheline. 4. The thickness of crystalline layers increased with increasement of temperature and time.

• 생약학회지
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• 제27권2호
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• pp.91-95
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• 1996

In the course of searching for acetylcholinesterase inhibitors from crude drugs, it was found that total MeOH extract of Corydalis Tuber showed significant inhibitory effect on acetylcholinesterase. To isolate acetylcholinesterase inhibitors from Corydalis Tuber, total MeOH extract of the the crude drug was subjected to activity guided fractionation. The MeOH extract was suspended in water and fractionated with methylene chloride and subjected to acid-base fractionation. Silica gel column chromatography of the basic fraction which showed significant inhibitory effect on acetylcholinesterase was carried out and 5 subfractions (1-5) were obtained. From subtraction 4, compound I was isolated. The structure of isolated compound I was identified by spectroscopic parameters of $^1H-NMR$, $^{13}C-NMR$, EI-MS and FAB-MS. The compound I was identified as berberine. It was found from the Lineweaver-Burk plot that berberine was a reversible and specific inhibitor of acetylcholinesterase having 90% inhibitory effect at the concentration of $2.5{\mu}M$.

• 생약학회지
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• 제44권1호
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• pp.16-21
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• 2013

The fruits of Pourthiaea villosa were extracted with methanol and its extract was fractionated with n-hexane, methylene chloride, ethyl acetate and n-butanol. Repeated column chromatography of silica gel, sephadex LH-20 and HPLC led to the isolation of nine phenolic compounds from ethyl acetate soluble fraction. The chemical structures were elucidated as kaemferol-3-O-${\beta}$-D-glucopyranoside (astragalin) (1), isorhamnetin-3-O-${\beta}$-D-glucopyranoside (2), kaempferol-3-O-${\beta}$-D-xylopyranosyl($1{\rightarrow}2$)-${\alpha}$-L-rhamnopyranoside (3), caffeic acid (4), quercetin-3-O-${\beta}$-D-xylopyranosyl($1{\rightarrow}2$)-a-L-rhamnopyranoside (5), quercetin-3-O-${\beta}$-D-xylopyranosyl($1{\rightarrow}2$)-${\beta}$-D-glucopyranoside (6), quercetin-3-O-${\beta}$-D-xylopyranosyl($1{\rightarrow}2$)-${\beta}$-D-galactopyranoside (7), quercetin-3-O-${\alpha}$-L-rhamnopyranoside (quercitrin) (8), and kaempferol-3-O-${\alpha}$-L-rhamnopyranoside (afzelin) (9) by spectroscopic techniques. These compounds were isolated from this plant for the first time.

• 동의생리병리학회지
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• 제17권5호
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• pp.1235-1242
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• 2003

This study was performed for the investigation of vasodilatory effects of Crataegus pinnatifida Bunge and for isolation and structure determination of the constituent from the active fraction. The fruits of this herbal drug were extracted with 80% methanol, then fractioned successively with methylene chloride, ethylacetate and n-butanol. Among the fractions, ethyl acetate fraction exhibited the most effective vascular relaxation against phenylephrine-induced arterial contraction. In order to isolate the active constituent by activity-guided fractionation, this fraction was chromatographed on silica gel to yield seven subfractions. Among the subfractions, the active one showing the most potent vascular relaxation activity was further separated by prep. HPLC with reversed phase Microsorb C-18 column using 1 % acetic acid and methanol gradient solvent system to afford one pure compound, which revealed a potent vasodilatory effect. Instrumental analyses (NMR and mass spectrometry) of the isolated constituent indicated this compound to be (-)-epicatechin. The vasodilatory action mechanism of this compound should be further investigated.

• KIEAE Journal
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• 제6권2호
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• pp.11-18
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• 2006

In this research, Conducting an engineering properties experiment, this study examined basic properties of regional Hwangto. The results of experiments are as followings. 1) This study confirmed that a result of examining lime order for Hwangto and comparison of stimulants, this study confirmed that 28 day's strength promotion is found in case of calcium hydroxide(Ca(OH)2) and calcium chloride(CaCl2) stimulant. Finally, it is known the fact that lime highly improves the weak strength of Hwangtoh. 2) As XRD analysis for proving the strength manifestation principle of Hwangto by regions, CSH figure and CASH figure appeared in each regional Hwangto in all the strength areas. This result could be appeared through hydraulicity from reaction of alkali stimulant and water, and pozzolan reaction(CSH figure) and $Str{\ddot{a}}tlingite$ reaction(CASH figure) by silica (SiO2) ingredient and calcium hydroxide (Ca(OH)2) among ingredients of clay, and alumina(Al2O3). 3) In result of strength analysis, It is knowned that the Gyeongsangdo Hwangto is stronger than the Jeollado Hwangto in reactivity.

• Computers and Concrete
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• 제13권4호
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• pp.423-436
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• 2014

Ground Granulated Blast Furnace Slag (GGBFS) is widely used as an effective partial cement replacement material. GGBFS inclusion has already been proven to improve several performance characteristics of concrete. GGBFS provides enhanced durability, including high resistance to chloride penetration and protection against alkali silica reaction. In this paper results of an experimental research work on influence of low-reactivity GGBFS (which is largely available in Iran) on the properties of mortars and concretes are reported. In the first stage, influence of GGBFS replacement level and fineness on the compressive strength of mortars was investigated using Taguchi method. The analysis of mean (ANOM) statistical approach was also adopted to develop the optimal conditions. Next, based on the obtained results, concrete mixtures were designed and water penetration, capillary absorption, surface resistivity, and compressive strength tests were carried out on highstrength concrete specimens at different ages up to 90 days. The results indicated that 7-day compressive strength is adversely affected by GGBFS inclusion, while the negative effect is less evident at later ages. Also, it was inferred that use of low-reactivity GGBFS (at moderate levels such as 20% and 30%) can enhance the impermeability of high-strength concrete since 28 days age.

• Preventive Nutrition and Food Science
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• 제1권1호
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• pp.59-63
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• 1996

The antimicrobial activity of mugwort(artemisia asiatica Nakai) was investigated. The methanol extract or dried mugwort was fractionated to hexane, chloroform, ethylacetate, butanol, and aqueous fractions. The hexane fraction among these fractions showed the hifhest inhibitory effect on the growth of microorganisms such as Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Lactobacillus plantarum. Bacillus subtilis, Escherchia coli, and Staphylococcus aureus were completely inhibited at a concentration of 250, 500 , and 750$\mu\textrm{g}$/ml respectively. The hexane fraction was further fractionated into 16 subfractions by silica gel column and thin layer chromatography(TLC). The subfraction No. 8, 9, and 10 on TLC exhibited high antimicrnial activity. At 3rd fractionation, subfraction No. 2 inhibited the growth of microorganisms at 500$\mu\textrm{g}$/ml. Heptadecane, dodecamethyi cyclohexasiloxane, (E,E)-2,4-decadienal, dodecamethul pentasiloxane, coumarin, 5,6,6,6a-tetrahydro-4,4,7a-trimethyl-2(4H)-benzofuranone, neophytadiene, tridecanoic acid, methyl ester, 2-methyl-4,5-nonadiene, (Z,Z)-9-12-octadecadienoyl chloride, and bis(2-ethylhexyl) were identified from this antimicrobial fraction by GC-MS.

• 한국환경과학회지
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• 제14권4호
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• pp.413-425
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• 2005

The 16 priority PAHs (Polycyclic Aromatic Hydrocarbons) designated by US Environmental Protection Agency were analyzed for some digested sludges from wastewater treatment plants in Korea. PAHs are an important group of organic contaminants present in sewage sludge due to their persistence and toxic potential. PAHs were extracted from freeze-dried sludges using a methylene chloride-methanol (2:1) mixture in a soxhlet extractor. The extracts were cleaned-up by silica gel/alumina combination column and subsequently fed into gas chromatograph/mass spectrometer (GC/MS) for determining PAH contents. The sum of the 16 PAHs in the sewage sludge varied from 534.8 to $5754.5 {\cal}ug/{\cal}kg$, dry wt.. In the sewage sludge, phenanthrene appears as the most abundant PAHs, followed by naphthalene, pyrene, fluoranthene. Source of the investigated sewage sludges relatively predominated pyrogenic. PAHs levels of sewage sludges in Korea appeared to be lower than those in other countries.