• Bulletin of the Korean Chemical Society
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• 제22권8호
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• pp.793-794
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• 2001

• 한국재료학회지
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• 제20권2호
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• pp.55-59
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• 2010

$Na^+$ ion conductivity can be improved by the substitution of an Mg atom for an Al atom to form a nonstoichiometric $Na^+$ $\beta$-alumina. We performed a first principles study to investigate the most stable substitution site of an Mg atom and the resulting structural change of the nonstoichiometric $Na^+$ $\beta$-alumina. Al atoms were classified as four different layers in the spinel block that are separated by conduction planes in the nonstoichiometric $Na^+$ $\beta$-alumina. The substitution of an Mg atom for an Al atom at a tetragonal site was more favorable than that at an octahedral site. The substitution in the spinel block was more favorable than that close to the conduction plane. This result was well explained by the volume changes of the polyhedrons, by the standard deviation of the Mg-O distance, and by the comparison with bulk MgO structure. Our result indicates that the most preferable site for the Mg atom was the tetrahedral site at the spinel block in the nonstoichiometric $Na^+$ $\beta$-alumina.

• Journal of Nutrition and Health
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• 제32권4호
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• pp.376-383
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• 1999

The effects of $\beta$-carotene substitutionl for vitamin A and the chronic consumption of ethanol of ethanol on hepatic folate metabolism were studied it rats. The substitution of $\beta$-carotene for vitamin A depressed hepatic 10-formyl-tetreahydrofolate dehydrogenase(10-formyl-tetrahydrofolate : NADP oxidoreductase, E.C. 1.5. 1.6)activity to 65% of controls(p<0.001) and enhanced hepatic 5, 10-methy-lenetetrahydrofolate reductase(E. C. 6.3.3.2)activity by 56% with respect to control levels(p<0.001). Hepatic activity of 10-formyltertrahydrofolate dehydrogenase was depressed to about half that of control levels by ethanol administration to rats(36% ethanol diet, p<0.001). The activity of 5, 10-methyleneterahydrofolate reductase was not changed by ethanol consumption. The increased activity of 5, 10-methyleneterahydrofolate reductase and the decreased activity of 10-formyltetrahydrofolate dehydrogenase appeared to decrease the level of nonmethyl folate conezyme and the rate of one-carbon metabolism. Plasma homocysteine concentrations were significantly higher in rats fed ethanol(p<0.01) o $\beta$-carotene(p<0.001) than in controls, which suggests that increased activity of 5, 10-methylenetetrahydrofolate reductase can depress homocysteine metabolism. We concluded that dietary substitution of $\beta$-carotene for vitamin A or chronic administration of ethanol resulted in changes in the activity of hepatic folate-dependent enzymes, which could affect the distribution of folate derivatives, plasma homocysteine levels and one-carbon metabolism.

• Bulletin of the Korean Chemical Society
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• 제26권1호
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• pp.157-160
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• 2005

Allylindium and propargylindium reagents in situ generated from the reactions of indium with allyl halides and propargyl halides could participate as nucleophiles in Pd-catalyzed substitution reactions of allyl carbonates to produce 1,5-dienes and 1,5-enynes in good yields. $\beta$-Hydride elimination products were produced in case of carbonates having $\beta$-hydrogens. Because organoindium reagents obtained from allyl or propargyl halides and indium have previously not been used to Pd-catalyzed allylic and propargylic substitution reactions, these results should provide more opportunities for the development of new C-C bond forming reactions.

• 대한화학회지
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• 제10권4호
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• pp.158-160
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• 1966

여러가지 nucleophile을 써서 3,4-methylene-dioxy-${\beta}$-nitrostyrene에 대한 nucleophilic addition constant를 측정하여 이미 알려진 nucleophilic substitution constant와 비교해 보았더니, 이 둘 사이에는 비례관계가 성립되지 않으리라 생각된다. 이것을 정량적으로 취급하려면 앞으로 많은 nucleophile에 대해서 더욱 정확한 실험치를 얻을 수 있어야 하겠다.

• 한국식생활문화학회지
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• 제16권4호
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• pp.316-322
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• 2001

This study was performed to investigate flavor modification effects of ${\beta}-cyclodextrin$ $({\beta}-CD)$ inclusion complex on the flavor of Doenjang (Korean traditional fermented soy paste) with various substitution levels of 10, 20, and 30%. Water and protein contents of the substituted samples showed significantly lower values compared to those of control(p<0.05). Results of DSC(Differential Scanning Calorimetry) showed that significantly higher ${\Delta}H$ values (386.03 and 304.23) in the 20 and 30% substituted samples represented the stabilized internal cell structures(p<0.05). Internal structures observed with the scanning electronic microscope tended to be less rough and organized making even and ordered internal cell structures as the substitution levels were increased. Results of sensory evaluation showed significantly higher savory flavor and significantly lower bitter and astringent flavors with the substituted samples compared to those of control(p<0.05). Results from this study showed the substitutions of ${\beta}-CD$ could possibly modify unfavored flavors of Doenjang while keeping the unique, nutritional and functional properties when ${\beta}-CD$ was used as a flavor modifier.

• Journal of Plant Biology
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• 제38권3호
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• pp.259-266
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• 1995

To investigate how the dyad symmetry region (DSR) and the distance between vir box and -35 sequence of the virE promoter plays a role in virE gene expression, two mutants were constructed by base substitution and insertional mutagenesis. The base substitutional mutation, a AAlongrightarrowCG substitution at positions -39 and -40 on the DSR, showed the level of $\beta$-galactosidase activity approximately 91% of the wild type virE promoter activity. Therefore, the native structure of the DSR seems to be not essential for virE expression. The insertional mutation, constructed by inserting 8 bp ClaI linker between -49 and -50, displayed the $\beta$-galactosidase activity at 12% of the native virE promoter activity. However, this striking reduction appears to be not caused by destruction of the native DSR structure, but by shifting the vir box far from putative -35 sequence.

• 한국자기공명학회논문지
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• 제22권4호
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• pp.115-118
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• 2018

Dipyrromethane 2 functionalized with 3-chloropropyl group on the meso carbon undergoes an unusual intramolecular electrophilic aromatic substitution reaction in the presence of $NaN_3$ instead of a simple nucleophilic substitution reaction. As a result, a new chiral dipyrromethane 1 was synthesized. In this reaction, the ${\beta}$-carbon of the pyrrole ring functions as a nucleophile while the carbon next to the chlorine atom acts as an electrophile. Interestingly, this reaction progresses even in the absence of an acid catalyst. Compound 1 was fully characterized by $^1H-^1H$ and $^1H-^{13}C$ COSY NMR spectroscopic analyses and the high resolution EI mass spectrometry.

• 방사선산업학회지
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• 제10권4호
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• pp.181-187
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• 2016

Selective ${\beta}_1$-agonist and antagonists are used for the treatment of cardiac diseases including congestive heart failure, angina pectoris and arrhythmia. Selective ${\beta}_1$-antagonists including nebivolol have high binding affinity on ${\beta}_1$-adrenergic receptor, not ${\beta}_2$-receptor mainly expressed in smooth muscle. Nebivolol is one of most selective ${\beta}_1$-blockers in clinically used ${\beta}_1$-blockers including atenolol and bisoprolol. We tried to develop clinically useful cardiac PET tracers using a selective ${\beta}_1$-blocker. Nebivolol is $C_2$-symmetric and has two chromane moiety with a secondary amino alcohol and aromatic fluorine. We adopted the general synthetic strategy using epoxide ring opening reaction. Unlike formal synthesis of nebivolol, we prepared two chromane building blocks with fluorine and iodine which was transformed to diaryliodonium salt for labelling of $^{18}F$. Two epoxide building blocks were readily prepared from commercially available chromene carboxylic acids (1, 8). Then, the amino alcohol building block (15) was prepared by ammonolysis of epoxide (14) followed by coupling reaction with the other building block, epoxide (7). Diaryliodonium salt, a precursor for $^{18}F$-aromatic substitution, was synthesized in moderate yield which was readily subjected to $^{18}F$-aromatic substitution to give $^{18}F$-labelled nebivolol.

• Archives of Pharmacal Research
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• 제28권12호
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• pp.1317-1323
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• 2005

In an attempt to examine the ability of benzisothiazole-based drugs to interact with $\beta$-adrenoceptors, a series of 1,2-benzisothiazole derivatives, which were substituted with various propanolamine or oxypropanolamine side chains in the 2 or 3 position, were synthesised and tested. The pharmacological activity of these compounds at the ,$\beta$-adrenoceptors was examined using isolated rat atria and small intestinal segments, which preferentially express the $\beta_{1}$- and $\beta_{3}$-adrenoceptor-mediated responses, respectively. None of these products showed any $\beta$-adrenoceptor agonistic activity. In contrast, the 2- and 3-substituted isopropyl, tert-butyl, benzyl, and piperonyl derivatives 2a-d and 3a-d elicited surmountable inhibition of the isoprena­line-induced chronotropic effects in the atria, suggesting competitive antagonism at the $\beta_{1}$­recognition site. The $pA_{2}$ values revealed tert-butyl 3b and the isopropyl substituted piperonyl derivatives 3a to be the most effective. Remarkably, many of the 2-substituted propanolamines were less active than the corresponding 3-substituted oxypropanolamines. With the exception of compound 3b, none of these drugs antagonised the muscle relaxant activity of isoprenaline in the intestine, suggesting no effect on the $\beta_{3}$-adrenoceptors. These results confirm the ability of the benzisothiazole ring to interact with the $\beta$-adrenoceptors, and demonstrate that 2-substitution with propanolamine or 3-substitution with oxypropanolamine groups yields compounds with preferential antagonistic activity at the cardiac $\beta_{1}$adrenoceptors. The degree of antagonism depends strongly on both the nature of the substituent and its position on the benzisothiazole ring.