• 한국세라믹학회지
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• 제28권9호
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• pp.705-711
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• 1991

Alumina precursor sol was obtained by the reaction of Al(OC4H9)3 and acetylacetone in the solvent followed by the partial hydrolysis. This sol was measured by viscosity and the effect of pH. The powders obtained from this sol were calcined at the various temperatures. The transition of crystals and crystal state were investigated at the various temperatures. The powders dried at 90$^{\circ}C$ showed amorphous and ${\gamma}$-Al2O3 at 900$^{\circ}C$, ${\alpha}$-Al2O3 mono-phase at 1050$^{\circ}C$ respectively. As a result of Al27-MASNMR analysis, amorphous and ${\alpha}$-Al2O3 powders showed 6-coordinated Al, ${\gamma}$-Al2O3 4-coordinated Al respectively.

• 생약학회지
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• 제9권2호
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• pp.93-97
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• 1978

From the crude saponin obtained from the pods of Gleditschia officinalis seven spots were identified by TLC and quantity of gleditschia B was the highest among them. Ten kinds of prosapogenins were identified from the partial hydrolysates of crude saponin and found that prosapogenin E contain oleanolic acid as a sapogenin and prosapogenin F does echinocystic acid as the sapogenin. Hydrolysis of crude saponin yield glucose and rhamnose and the same sugar were also identified from the mixture of prosapogenin E and F.

• 한국세라믹학회지
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• 제20권1호
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• pp.3-12
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• 1983

In the present study an attempt was made to synthesize the $Al_2O_3$.$2SiO_2$ glass in which atomic ratio is Al:Si=1:1 by sol-gel process. And at such a low temperature as 55$0^{\circ}C$ clear amorphous gel derived glass with Si-O-Al bonding was obtained. $Si(OC_2H_5)_4$ and $Al(NO_3)_3$.$9H_2O$ were used as the precursor and among the mutual solvents only n-butanol gave good results for the synthesis of the gel derived glass. Partial hydrolysis of TEOS with one-fold mol of $H_2O$ prior to the reaction with aluminum nitrate gave the better results., Total oxide content to the total reactants by weight was affective to the results.

• 한국자기공명학회논문지
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• 제10권2호
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• pp.188-196
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• 2006

A known theonellapeptolide Ie, previously reported in other research group, was isolated from the methanolic extract of the Philippine sponge Theonella swinhoei. The planar structure of this compound was determined on the basis of NMR methods including HMBC and selective HMBC experiments. This is fast and efficient for the dereplication of natural products compared with the MS studies of fragments obtained from complete and partial hydrolysis. The sequence of thirteen amino acids including six N-methyl amino acids in the compound was clearly determined from correlations of extensive HMBC experiments.

• Bulletin of the Korean Chemical Society
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• 제20권8호
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• pp.893-896
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• 1999

Novel citric acid based Ti, Nb and Ta precursors that are highly stable in the presence of water were developed. No alkoxides of Ti, Nb and Ta were utilized in the preparation, instead much less moisture-sensitive metallic Ti, NbCl5 and TaCl5 were chosen as starting chemicals for Ti, Nb and Ta, respectively. The feasibility of these chemicals as precursors is demonstrated in the powder synthesis of BaTi4O9, Y3NbO7 and LiTaO3. The water-resistant Ti precursor was employed as a new source of water-soluble Ti in the amorphous citrate method, and phase pure BaTi4O9 in powdered form was successfully synthesized at 800 ？. The Pechini-type polymerizable complex method using the water-resistant Nb and Ta precursors was applied to the synthesis of Y3NbO7 and LiTaO3, and both the powder materials in their pure form were successfully synthesized at reduced tempera-tures, viz. 500-700 ？. The remarkable retardation of hydrolysis of these water-resistant precursors is explained in terms of the partial charge model theory.

• Journal of Microbiology and Biotechnology
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• 제17권8호
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• pp.1291-1299
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• 2007

Two ${\beta}$-1,4-glucanases (DI and DIII fractions) were purified to homogeneity from the culture filtrate of a cellulolytic bacteria, Cellulomonas sp. CS 1-1, which was classified as a novel species belonging to Cellulomonas uda based on chemotaxanomic and phylogenetic analyses. The molecular mass was estimated as 50,000 Da and 52,000 Da for DI and DIII, respectively. Moreover, DIII was identified as a glycoprotein with a pI of 3.8, and DI was identified as a non-glycoprotein with a pI of 5.3. When comparing the ratio of the CMC-saccharifying activity and CMC-liquefying activity, DI exhibited a steep slope, characteristic of an endoglucanase, whereas DIII exhibited a low slope, characteristic of an exoglucanase. The substrate specificity of the purified enzymes revealed that DI efficiently hydrolyzed CMC as well as xylan, whereas DIII exhibited a high activity on microcrystalline celluloses, such as Sigmacells. A comparison of the hydrolysis patterns for pNP-glucosides (DP 2-5) using an HPLC analysis demonstrated that the halosidic bond 3 from the nonreducing end was the preferential cleavage site for DI, whereas bond 2, from which the cellobiose unit is split off, was the preferential cleavage site for DIII. The partial N-terminal amino acid sequences for the purified enzymes were $^1Ala-Gly-Ser-Thr-Leu-Gln-Ala-Ala-Ala-Ser-Glu-Ser-Gly-Arg-Tyr^{15}$-for DI and $^1Ala-Asp-Ser-Asp-Phe-Asn-Leu-Tyr-Val-Ala-Glu-Asn-Ala-Met-Lys^{15}$-for DIII. The apparent sequences exhibited high sequence similarities with other bacterial ${\beta}$-1,4-glucanases as well as ${\beta}$-1,4-xylanases.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1994년도 제2회 추계심포지움
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• pp.69-80
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• 1994

Although ureases play important roles in microbial nitrogen metabolism and in the pathogenesis of several human diseases, little is known of the mechanism of metallocenter biosynthesis in this Ni-Containing enzyme. Klebsiella aerogenes urease apo-protein was purified from cells grown in the absence of Ni. The purified apo-enzyme showed the same native molecular weight, charge, and subunit stoichiometry as the holo-enzyme. Chemical modification studies were consistent with histidinyl ligation of Ni. Apo-enzyme could not be activated by simple addition of Ni ions suggesting a requirement for a cellular factor. Deletion analysis showed that four accessory genes (ureD, ureE, ureF, and ureG) are necessary for the functional incorporation of the urease metallocenter. Whereas the $\Delta$ureD, $\Delta$ureF, and $\Delta$ureG mutants are inactive and their ureases lack Ni, the $\Delta$ureE mutants retain partial activity and their ureases possess corresponding lower levels of Ni. UreE and UreG peptides were identified by SDS-polyacrylamide gel comparisons of mutant and wild type cells and by N-terminal sequencing. UreD and UreF peptides, which are synthesized at ve교 low levels, were identified by using in vitro transcription/translation methods. Cotransformation of E. coli cells with the complementing plasmids confirmed that ureD and ureF gene products act in trans. UreE was purified and characterized. immunogold electron microscopic studies were used to localize UreE to the cytoplasm. Equilibrium dialysis studies of purified UreE with $^{63}$ NiC1$_2$ showed that it binds ～6 Ni in a specific manner with a $K_{d}$ of 9.6 $\pm$1.3 $\mu$M. Results from spectroscopic studies demonstrated that Ni ions are ligated by 5 histidinyl residues and a sixth N or O atom, consistent with participation of the polyhistidine tail at the carboxyl termini of the dimeric UreE in Ni binding. With these results and other known features of the urease-related gene products, a model for urease metallocenter biosynthesis is proposed in which UreE binds Ni and acts as a Ni donor to the urease apo-protein while UreG binds ATP and couples its Hydrolysis to the Ni incorporation process.ouples its Hydrolysis to the Ni incorporation process.s.

• 약학회지
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• 제11권1_2호
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• pp.7-16
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• 1967

A yellowish microneedles, $C_{28}$ H$_{32}$ $O_{14}$ ${\cdot}$ I$_{1}$/$_2$, H$_{2}$O, m.p.262-$4^{\circ}$ , [${\alpha}$$_{D}^{20}$= -71,$43^{\circ}$(C = 0.42, pyridine), its acetate m.p.123-5.deg., were obtained in 0.3% yield from the leaves of Chrysanthemum sibiricum F$_{ISCHER}$. This substance is insoluble in water and the usual organic solvents except pyridine and ethylene glycol and, is not decomposed by dilute mineral acids but undergoes decomposition on being boiled in 60% H$_{2}$SO$_{4}$ or 35% HCl, giving one moel each of acacetin, glucose and rhamnose. It was not hydrolysed with a rhamnodiastase preparation obtained from the seeds of Rhamnus koraiensis. After permethylation of it, the uncrystallized product was hydrolysed and apigenin-5,4'-dimethyl ehter, m.p.$262^{\circ}$ was obtained, indicating that the disaccharide residue is at the 7 position of acacetin. Partial hydrolysis of this acacetin-7-rhamnoglucoside in cyclohexanol with formic acid gave acacetin-7-glucoside, m.p.246.deg. and rutinose, identifying them with authentic specimen on a paper chromatography. It was thus identified as linarin(acacetin-7-rutinoside) by means of mixed fusion, of paper partition chromatography and of its derivatives. Zemplen and Bognar suggested that the glucosidic linkage of linarin is .betha. by means of synthesis of this substance. But there is no evidence whether it is hydrolysed by emulsin or maltase or not. Linarin itself was not hydrolysed by an emulsin existing in the seed of Apricot or a maltase, but acacetin-7-glucoside(tilianin) which obtained from linarin gave acacetin and glucose on hydrolysis with the same emulsin and accordingly the glucosidic linkages of linarin and tilianin are thus regarded as ${\beta}$.

• 한국식품영양학회지
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• 제10권1호
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• pp.102-109
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• 1997

효소반응과 부분 산가수분해 결과를 해석하여 Leuconostoc mesenteriodes M-12 덱스트란수크라제 억셉터 반응 산물인 새로운 분지올리고당의 구조를 확인하였다. 분지올리고당 B4의 구조는 62-O-$\alpha$-D-kojibiosylmaltose인 것으로 확인되었으며, 분지올리고당 B5의 구조는 63-O-$\alpha$-D-kojibiosylpanose였다. 억셉터 반응산물을 덱스트라나제로 분해한 결과 새로운 올리고당인 D4를 확인할 수 있었다. 억셉터 반응산물을 억셉터로 이용한 두 번째 억셉터 반응의 생성물을 덱스트라나제 처리하여 D4를 얻었는데 덱스트라나제와 글\ulcorner아밀라제에 의해 분해되지 않았다. 그 구조는 62-O-$\alpha$-D-kojibiosylisomaltose로 확인되었다. 직선상 또는 분지 결합을 가진 d.p. 6 이하의 억셉터 반응산물의 생성 패턴도 확인하였다.

• KSBB Journal
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• 제14권2호
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• pp.230-234
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• 1999

한외여과공정에서 압력구배를 주기적으로 변화시켜 막 표면의 용질층을 불안정화시켜 여과 flux의 총괄적 향상을 유도한 실험을 수행하였다. 일정압력에서의 여과 flux 감소현상을 Hernia 식을 사용하여 모사하였고, 또한 압력구배의 주기적 변화를 Fourer series로 표현하여 압력구배의 변화에 따른 flux 변화를 수학적으로 모사하였고 이 결과를 실제의 실험결과와 비교하여 보았다. 수학적 모사결과 압력변화의 형태, 진폭, 주기 등의 변화에 따른 평균 flux의 변화는 미미하였다. 하지만 실제실험결과 주기적으로 압력구배를 변화시킨 경우 약 11%의 향상을 관찰할 수 있었다. 이는 압력구배가 주기적으로 변하는 과정에서의 응질층의 압축이완속도가 다른 것에 기인하는 것으로 유추된다. 주기적 압력구배변화외에 feed pump interruption을 이용하여 평균총괄 flux를 약 32%까지 향상 시켰다. 역확산에 의한 용질층의 이완에는 일정한 시간이 필요함을 찾아내었고 interruption은 용질층이 형성되기 전부터 시작하는 것이 유리하다고 판단되었다. 본 실험을 위하여 한외여과의 자동제어 시스템을 설계제작하여 다양한 압력함수를 이용할 수 있었고, 공정운영 중 압력구매와 여과 flux를 실시간 모니터링 및 제어할 수 있었다. 자동제어 시스템을 통해 압력구매를 주기적으로 변화시켜 총괄 flux의 극대화를 도모하는 기법은 기존장치를 최소로 변경시키면서 한외여과성능을 극대화시킬 수 있는 방법으로 기대된다.