• Research in Mathematical Education
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• v.17 no.4
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• pp.221-241
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• 2013

The data for the present paper was a part of a large research project conducted to assess preservice teachers' knowledge related to fractions and place value at a southwestern public university in 2007. The study utilized convenience sampling, consisting of 150 elementary preservice teachers who were enrolled in a mathematics methods course before their student teaching. The results demonstrated preservice teachers' knowledge of teaching comparison, addition, subtraction, and multiplication of fractions was insufficient even though these should be basic knowledge. Teacher preparation programs should emphasize profound knowledge for teaching fractions using representations.

• Molecular & Cellular Toxicology
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• v.5 no.3
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• pp.237-242
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• 2009

The potential antioxidant activities of different fractions from methanolic extract of Curcuma longa L. were assayed in vitro. All of the fractions exception of n-hexane and $H_2O$ showed a strong antioxidant activity, especially the ethylacetate (EtOAc) fraction, which showed the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity ($IC_{50}=9.86\;{\mu}g/mL$). The results of 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging activity and ferric reducing antioxidant power (FRAP) assay showed concentration dependency, the EtOAc fraction demonstrating a better result than the other fractions at the same concentration in this studies. Additionally, when the total phenolic contents of fractions were measured, the EtOAc fraction contained the highest level. Meanwhile, correlation analysis indicated a high correlation between the antiradical activity and the total phenolic contents, suggesting that fractions obtained from the methanolic extract of Curcuma longa L. have wide potential for use as sources of antioxidant material.

• The Mathematical Education
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• v.52 no.2
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• pp.217-230
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• 2013

This study attempts to propose the construction of textbook contents of fraction division and to suggest a method to strengthen the connection among problem context, manipulation activities and symbols by proposing an algorithm of dividing fractions based on problem contexts. As showing the suitable algorithm to problem context, it is able to understand meaningfully that the algorithm of fractions division is that of multiplication of a reciprocal. It also shows how to deal with remainder in the division of fractions. The results of this study are expected to make a meaningful contribution to textbook development for primary students.

• The Korean Journal of Pharmacology
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• v.5 no.1
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• pp.23-28
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• 1969

Saponin, essential oil and fat oil fractions were fractionated from Panax Ginseng and their potentiating or inhibiting actions during the combined use of several central nervous system stimulants or depressants were observed to elucidate the possible role of Ginseng fractions on the central nervous system. Saponin, essential oil and fat oil fractions shortened nembutal sleeping time at low dosage (10 mg/kg) but contrarily they produced potentiation of nembutal hypnosis at high dosage (50mg/kg). In the toxicity study of amphetamine, saponin and essential oil fractions reduced the toxicity in aggregated mice at high dosage (100 mg/kg) but such decreased lethality was not observed in isolated mice. Ginseng fractions, especially high dose of saponin fraction (100mg/kg) prolonged the survival time after injection of convulsive dose of metrazol or cocaine and saponin fraction also prolonged the onset of cocaine convulsion at high dosage (100 mg/kg).

• Journal of Ginseng Research
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• v.17 no.3
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• pp.210-218
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• 1993

This study was conducted to investigate the effects of Korean ginseng extracts and their fractions on the growth of Saccharomyces cerevsiae and Saccharomyces uvamm, their glucose consumption and alcohol production. The growth of both yeasts were stimulated by ginseng extracts and their water soluble fractions, but were supressed by ether extracts and an n-butanol extracts. Their growth were enhanced considerably by low molecular weight fractions (< 1,000) in water solubles. Similar results were also obtained with glucose consumption by yeasts. Substances increasing the growth and glucose consumption by yeasts proved to be a low molecular weight fractions (<1,000) in water solubles not saponins. The production of n-propyl alcohol by yeast was enhanced by adding ginseng extracts into the media, but that of ism-butyl alcohol was suppressed at same condition.

• International Journal of Oral Biology
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• v.36 no.3
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• pp.149-154
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• 2011

In the present study, total methanol extracts prepared from Alpinia katsumadai showed significant protective effects against the oxidative stress induced by hydrogen peroxide, UV-C or ${\gamma}$-ray irradiation. These protective effects were substantially increased by treatment with 20~100 ${\mu}g$/ml of the extract. The A. katsumadai total methanol preparation was further fractionated into n-hexane, dichloromethane, ethylacetate, n-butanol and water fractions. Among these five fractions, the ethylacetate and butanol fractions of A. katsumadai showed the strongest protective effects against oxidative stress induced by UV-C and ${\gamma}$-ray irradiation. These fractions also showed high DPPH radical scavenging and lipid peroxidation inhibitory activities. In addition, both fractions displayed cell proliferation activation effects, as evidenced by significant increases in colony formation. Our current data thus suggest that the mechanisms underlying the protective effects of A. katsumadai against oxidative damage may include radical scavenging, protection against cell membrane damage and stimulation of cell proliferation.

• Research in Mathematical Education
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• v.10 no.3 s.27
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• pp.189-203
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• 2006

Teaching of fractions is very challengeable for elementary and middle school teachers. Many teachers feel uncomfortable teaching the subject. How shall we introduce the concept of fractions? Shall we focus more on concept development or computational procedures and skills? What methodology can be used in teaching those important topics? These are the kind of questions many teachers and researchers try to answer. In this article, the authors are to look at this issue from a cross nation perspective, by examining how the Chinese mathematics curriculum and the Chinese teachers deal with this subject.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.2
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• pp.194-200
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• 2014

This study investigated the chemical composition and ruminal degradability of corn stover in three maize-planting regions in Qiqihaer, Heilongjiang Province, China. The whole stover was separated into seven morphological fractions, i.e., leaf blade, leaf sheath, stem rind, stem pith, stem node, ear husk, and corn tassel. The assessment of nutritive value of corn stover and its fractions was performed based on laboratory assays of the morphological proportions, chemical composition, and in situ degradability of dry matter (DM), neutral detergent fiber (NDF), and acid detergent fiber (ADF). The chemical composition of corn stover was significantly different from plant top to bottom (p<0.05). Among the whole corn stover and seven morphological fractions, leaf blade had the highest crude protein (CP) content and the lowest NDF and ADF contents (p<0.05), whereas stem rind had the lowest CP content and the highest ADF and acid detergent lignin (ADL) contents (p<0.05). Ear husk had significantly higher NDF content and relatively lower ADL content than other corn stover fractions. Overall, the effective degradability of DM, NDF, and ADF in rumen was the highest in leaf blade and stem pith, followed by ear husk. The results indicate that leaf blade, ear husk, and stem pith potentially have higher nutritive values than the other fractions of corn stover. This study provides reference data for high-efficiency use of corn stover in feeding ruminants.

• KSBB Journal
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• v.30 no.6
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• pp.302-306
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• 2015

In this work, the antioxidant activity and total phenolic compound content of 6 fractions of Smallanthus sonchifolius, Agrimonia pilosa, and Lithospermum erythrorhizon extract were investigated. The highest total phenolic compound contents of each plant extracts were obtained from n-butanol ($13.75{\pm}0.21%$) and methylene chloride ($12.89{\pm}1.10%$) fractions (S. sonchifolius), ethyl acetate ($19.69{\pm}1.02%$) and water ($18.72{\pm}0.76%$) fractions (A. pilosa), and n-butanol ($36.26{\pm}1.26%$) and ethyl acetate ($17.66{\pm}0.94%$) fractions (L. erythrorhizon), respectively. As a result of DPPH radical scavenging activity in 10 mg/mL condition, the highest activity were obtained from n-butanol fraction of S. sonchifolius (81.06%), ethyl acetate fraction of A. pilosa (86.32%), and n-butanol fraction of L. erythrorhizon (82.6%), respectively. Also, the highest reducing power was obtained same fractions as well as DPPH adical scavenging activity. Overall, antioxidant activity has relatively closely connected with contents of total phenolic compounds in S. sonchifolius and L. erythrorhizon extracts.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.202-202
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• 1996

The antihistaminic action of eighteen herbal medicines was investigated by the radioligand binding and functional assays. The hexane fractions of Trichosanthis radix, Mori cortex radicis and Evodiae fructus dose-dependently inhibited [$^3$H]mepyramine binding to H$_1$ receptor and histamine-induced contraction in guinea-pig brain homogenates and isolated guinea-pig ilea, respectively. Antihistaminic action of the hexane and ethylacetate fractions of Mori cortex radicis and the hexane fraction of Evodiae fructus was more potent than their antimuscarinic action evaluated from the inhibition of [$^3$H]QNB binding and carbachol response. The ethylacetate and chloroform fractions and six known flavonoids from Scutellariae radix also inhibited histamine-induced contraction, but antihistaminic potencies of these fractions and compounds were almost identical with their antimuscarinic potencies. The hexane fractions of Mori cortex radicis and Evodiae fructus, as shown in ketotifen, inhibited selectively the increase of cutaneous vascular permeability induced by histamine. However, wogonin (SC-1) from Scutellariae radix was a nonselective inhibitor for the effect of histamine and serotonin on the vascular permeability. These results demonstrate that the hexane and ethylacetate fractions of Mori cortex radicis and the hexane fraction of Evodiae fructus have the selective histamine H$_1$ receptor blocking activities.