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CC Chen

Publications and source records attributed to CC Chen.

14 recordsLinked to original sources
PubMed2000

Heterogeneous Nucleation of n-Butanol Vapor on Submicrometer Charged and Neutral Particles of Lactose and Monosodium Glutamate.

Condensation of a supersaturated vapor of n-butanol on monodisperse submicrometer particles of lactose and monosodium glutamate is investigated in a flow cloud chamber (FCC). The dependence of critical supersaturation S(cr) on the particle size in the range 30 to 90 nm is experimentally examined. The results show that the size dependence of S(cr) qualitatively agrees with that predicted by the Fletcher version of the Volmer theory of heterogeneous nucleation, but to a lesser degree. The experimental S(cr) is smaller than the theoretical prediction even with the line tension and surface diffusion taken into account, and they induce heterogeneous nucleation better than perfectly wetted particles. The discrepancy can not be fully accounted for by the effects of line tension and surface diffusion and the existing theory concerning the curvature-dependent surface tension. The condensation on single positive-charged particles of diameter 30, 60, and 90 nm is also examined. A lowering of S(cr) at an efficiency much larger than the prediction by Volmer's theory for ion-induced nucleation is observed, and the charge effect fades away as particle size increases. Copyright 2000 Academic Press.

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PubMed1999

Heterogeneous Nucleation of n-Butanol Vapor on Submicrometer Particles of SiO2 and TiO2.

Condensation of a supersaturated vapor of n-butanol on monodisperse submicrometer particles is investigated in a flow cloud chamber (FCC). The size dependence of critical supersaturation in the range of 20 to 90 nm is experimentally determined. Two types of aerosol, SiO2 and TiO2, are tested. The results show that both aerosols induce heterogeneous nucleation better than perfectly wetted particles. The experimental critical supersaturation is smaller than that predicted by the Fletcher version of Volmer theory of heterogeneous nucleation even with the line tension and surface diffusion taken into account and has a size dependence in qualitative agreement with that theoretically predicted but to a lesser degree. The discrepancy can not be fully accounted for by the effects of line tension and surface diffusion and the existing theory concerning the curvature-dependent physical properties. The law of corresponding states was extended to the heterogeneous nucleation, and a simple correlation was observed. We conclude that the macroscopic theory of heterogeneous nucleation leads to a prediction of critical supersaturation higher than that experimentally measured. Copyright 1999 Academic Press.

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PubMed1998

Six New Diarylbutane Lignans from Justicia procumbens

Six new diarylbutane lignans, namely, justin A (1), (-)-dihydroclusin diacetate (2), secoisolariciresinol dimethyl ether diacetate (3), 5-methoxy-4,4'-di-O-methylsecolariciresinol diacetate (4), justin B (5), and justin C (6), together with three known diarylbutane lignans [2,3-demethoxysecisolintetralin acetate (7), secoisolariciresinol dimethyl ether (8), and 5-methoxy-4,4'-di-O-methylsecolariciresinol (9)], were isolated from the whole plant of Justicia procumbens. Their structures were established by spectral analysis.

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PubMed1998

Tannins, flavonol sulfonates, and a norlignan from phyllanthus virgatus

Investigation of the constituents of Phyllanthus virgatus has led to the isolation of five new compounds, including a norlignan, 2-(3, 4-methylenedioxybenzyl)-4-(3,4-methylenedioxyphenyl)-3-butyne-1, 2-diol named virgatyne (1); a hydrolyzable tannin, virganin (2); and three flavonoid sulfonates, galangin-8-sulfonate (4), galangin-3-O-beta-D-glucoside-8-sulfonate (5), and kaempferol-8-sulfonate (6). Their structures were established by spectral and chemical methods.

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PubMed1998

Two new constituents from the leaves of magnolia coco

A new amide, magnolamide (1), and a new lignan, magnolone (2), whose structures were determined on the basis of spectral analysis, were found in the leaves of Magnolia coco. Eleven known compounds (episesamin, sesamin, magnolol, fargesin, aschantin, epieudesmin, syringaresinol, syringaresinol-O-beta-D-glucopyroside, scoparone, oxoanolobine, and dicentrinone) were also isolated.

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PubMed1997

Size Dependence of Structural Metastability in Semiconductor Nanocrystals

The kinetics of a first-order, solid-solid phase transition were investigated in the prototypical nanocrystal system CdSe as a function of crystallite size. In contrast to extended solids, nanocrystals convert from one structure to another by single nucleation events, and the transformations obey simple unimolecular kinetics. Barrier heights were observed to increase with increasing nanocrystal size, although they also depend on the nature of the nanocrystal surface. These results are analogous to magnetic phase transitions in nanocrystals and suggest general rules that may be of use in the discovery of new metastable phases.

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PubMed1993

Complications of Vertical Banded Gastroplasty and its Modified Operative Mode, K-Gastroplasty: a preliminary report.

Based on the experiences in performing vertical banded gastroplasty (VBG) for 8 years, its results were analyzed and particularly its operative complications were examined. As a result, its weight-reducing effect and safety were favorable, but serious complications, although few, were observed. These major complications were the loss of gastric reduction effect due to staple-line dehiscence, gastric band exposure, reflux esophagitis, channel narrowing, pouch ulcer, etc. As a preventive measure against these complications, to supplement the defects of VBG without losing its characteristics, K-gastroplasty was devised and performed; its operative mode is discussed.

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PubMed1992

A Clinical Study of Protein Sparing Modified Fast (PSMF) Administered Preoperatively to Morbidly Obese Patients: comparison of PSMF with natural food products to originally prepared PSMF.

Morbidly obese patients are generally in a malnutritional state with an extremely high operative risk. In order to reduce the operative risk, surgeons should make every effort before the operation. A protein sparing modified fast (PSMF) may exhibit its high effectiveness when taken at least for 2 weeks preoperatively. In this study, PSMF prescribed with natural food products was compared with prepared PSMF having an ideal composition from the clinical standpoint. Though it is natural for patients to favor the former, the latter proved to have a superior effect in clinical practice. By performing a PSMF for 2 weeks preoperatively, however, even the PSMF with natural food products seemed to fulfill its purpose sufficiently.

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