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371.
Tamanna Sultana Jae Mok Jung Seong-Soo Hong Won-Ki Lee Yeong-Soon Gal Hyun Gyu Kim Kwon Taek Lim 《Journal of inclusion phenomena and macrocyclic chemistry》2012,72(1-2):207-212
Inclusion properties of the drug omeprazole (OMP) with peracetylated-beta-cyclodextrin (PAc-β-CD) prepared by green method, following supercritical carbon-dioxide (scCO2), were characterized through thermal (TGA and DSC), crystalline (XRD), NMR spectroscopic and dissolution studies. Comparison amongst PAc-β-CD, OMP, physical binary mixture (equimolar ratio of OMP: PAc-β-CD) and the solid inclusion complex (OMP/PAc-β-CD) revealed scCO2 as a successful technique for inclusion complex formation as well, identified characteristics performances of PAc-β-CD/OMP interactions. For instance, absence of characteristic DSC or XRD peaks of either chemical in the complex was quite noticeable with the shift of proton peaks in 1H NMR spectra. The formed inclusion complex also showed an important dissolution performance of OMP for controlled release applications partly due to the hydrophobic nature of PAc-β-CD. 相似文献
372.
Sunbum Kwon Kyungtae Kang Aram Jeon Ji Hun Park Insung S. Choi Hee-Seung Lee 《Tetrahedron》2012,68(23):4368-4373
In this paper, we report the self-assembly phenomenon of trans-2-aminocyclopentanecarboxylic acid hexamer (ACPC6) by the evaporation-induced self-assembly. The SEM and TEM analyses of the self-assembled 3D molecular architecture revealed the characteristic shape of hollow parallelepiped and its supramolecular chiral expression on surface. A systematic study with the derivatives of ACPC6 showed the effect of the terminal groups of ACPC6 on the particular 3D shape formation. We also found that water molecules played a crucial role in the formation of hollow morphogenesis under the evaporation-induced self-assembly condition, and a plausible formation mechanism was suggested. 相似文献
373.
Chang-Yong Yun Dipesh Dhital Jung-Ryul Lee Gyuhae Park Il-Bum Kwon 《Optics & Laser Technology》2012,44(1):269-280
To prevent possible threats to public safety and economic loss from chemical leakage accidents, novel chemical sensing techniques for regular monitoring and leakage detection have been developed for various fields. We propose a fiber optic liquid chemical sensor (FOCS) system using specialty optical fibers and an optical time domain reflectometer (OTDR), and is based on the leaky wave mode sensing principle. OTDR enables simple multiplexing where individual sensor nodes along the fiber length could be interrogated by a common OTDR. The sensor node in the optical fiber is prepared by removing the desired length of a protective layer using mechanical stripping and chemical etching techniques. A novel laser stripping technique with superior capability to fabricate quasi-distributed dense sensor nodes is devised as well. The FOCS system is further analyzed to characterize the sensor response behavior in relation to the sensor node length and possible environmental and chemical temperature effect. Under the condition satisfying the leaky wave mode principle and within the minimum acceptable refractive index (RI) range by the system, this FOCS system could monitor numerous liquid chemicals with variable refractive indices and has been tested with positive results. In addition, the system shows the possibility for multi-point detection and is further expanded into a hybrid technique capable of estimating the refractive index range of the detected chemical. 相似文献
374.
In simulation studies of fluid-solid transitions, the solid phase is usually modeled as a constrained system in which each particle is confined to move in a single Wigner-Seitz cell. The constrained cell model has been used in the determination of fluid-solid coexistence via thermodynamic integration and other techniques. In the present work, the phase diagram of such a constrained system of Lennard-Jones particles is determined from constant-pressure simulations. The pressure-density isotherms exhibit inflection points which are interpreted as the mechanical stability limit of the solid phase. The phase diagram of the constrained system contains a critical and a triple point. The temperature and pressure at the critical and the triple point are both higher than those of the unconstrained system due to the reduction in the entropy caused by the single occupancy constraint. 相似文献
375.
Kwon BJ Perry TT Wilhelm CL Healy EW 《The Journal of the Acoustical Society of America》2012,131(4):3111-3119
Normal-hearing (NH) listeners maintain robust speech understanding in modulated noise by "glimpsing" portions of speech from a partially masked waveform--a phenomenon known as masking release (MR). Cochlear implant (CI) users, however, generally lack such resiliency. In previous studies, temporal masking of speech by noise occurred randomly, obscuring to what degree MR is attributable to the temporal overlap of speech and masker. In the present study, masker conditions were constructed to either promote (+MR) or suppress (-MR) masking release by controlling the degree of temporal overlap. Sentence recognition was measured in 14 CI subjects and 22 young-adult NH subjects. Normal-hearing subjects showed large amounts of masking release in the +MR condition and a marked difference between +MR and -MR conditions. In contrast, CI subjects demonstrated less effect of MR overall, and some displayed modulation interference as reflected by poorer performance in modulated maskers. These results suggest that the poor performance of typical CI users in noise might be accounted for by factors that extend beyond peripheral masking, such as reduced segmental boundaries between syllables or words. Encouragingly, the best CI users tested here could take advantage of masker fluctuations to better segregate the speech from the background. 相似文献
376.
Leader-following consensus criteria for multi-agent systems with time-varying delays and switching interconnection topologies
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We consider multi-agent systems with time-varying delays and switching interconnection topologies.By constructing a suitable Lyapunov-Krasovskii functional and using the reciprocally convex approach,new delay-dependent consensus criteria for the systems are established in terms of linear matrix inequalities(LMIs),which can be easily solved by using various effective optimization algorithms.Two numerical examples are given to illustrate the effectiveness of the proposed methods. 相似文献
377.
K.H. Kwon D.W. Lee F. Marcellán S.B. Park 《Annali di Matematica Pura ed Applicata》2001,180(2):127-146
Given an orthogonal polynomial system {Q
n
(x)}
n=0
∞, define another polynomial system by where α
n
are complex numbers and t is a positive integer. We find conditions for {P
n
(x)}
n=0
∞ to be an orthogonal polynomial system. When t=1 and α1≠0, it turns out that {Q
n
(x)}
n=0
∞ must be kernel polynomials for {P
n
(x)}
n=0
∞ for which we study, in detail, the location of zeros and semi-classical character.
Received: November 25, 1999; in final form: April 6, 2000?Published online: June 22, 2001 相似文献
378.
C M Jung H C Kwon J J Seo Y Ohizumi K Matsunaga S Saito K R Lee 《Chemical & pharmaceutical bulletin》2001,49(7):912-914
The aerial part of Aster scaber Thunb. (Asteraceae) yielded two new monoterpene peroxide glycosides, (3S)-3-O-(3',4'-diangeloyl-beta-D-glucopyranosyloxy)-7-hydroperoxy-3,7-dimethylocta-1,5-diene (1) and (3S)-3-O-(3',4'-diangeloyl-beta-D-glucopyranosyloxy)-6-hydroperoxy-3,7-dimethylocta-1,7-diene (2), and five known compounds, alpha-spinasterol (3), germacra-4(15),5,10(14)-triene-1-beta-ol (4), 7-methoxy-4(15)-oppositen-1-beta-ol (5), 6alpha-methoxy-4(15)-eudesmane-1beta-ol (6) and alpha-spinasterol 3-O-beta-D-glucopyranoside (7). The structures were established by chemical and spectroscopic methods. 相似文献
379.
Joong-Ho Kwon Myung-Woo Byun Kang-Soo Kim Il-Jun Kang 《Radiation Physics and Chemistry》2000,57(3-6):309-313
The hygienic, physicochemical, and organoleptic qualities of white ginseng were monitored during 6 months under accelerated conditions (40°C, 90% r.h.) by observing its microbial populations, disinfestation, and some quality attributes following either gamma irradiation at 2.5–10 kGy or commercial phosphine (PH3) fumigation. In a comparative study, both treatments were found to be effective for disinfecting the stored samples. Phosphine showed no appreciable decontaminating effects on microorganisms contaminated including coliforms, while 5 kGy irradiation was sufficient to control all microorganisms related to the quality of the packed samples. Irradiation at 5 kGy caused negligible changes in physicochemical attributes of the samples, such as ginsenosides, amino acids, fatty acids, and organoleptic properties, whereas phosphine fumigation was found detrimental to sensory flavor (P<0.01). Quality deterioration occurred in the commercially-packed samples was in the following order: the control, 10 kGy-, phosphine-, and 2.5–5 kGy-treated samples. Accordingly, irradiation at <5 kGy was found to be an effective alternative to phosphine fumigation for white ginseng. 相似文献
380.
The interlaminar fracture and the low-velocity impact behavior of carbon/epoxy composite materials have been studied using
width-tapered double cantilever beam (WTDCB), end-notched flexure (ENF), and Boeing impact specimens. The objectives of this
research are to determine the essential parameters governing interlaminar fracture and damage of realistic laminated composites
and to characterize a correlation between the critical strain energy release rates measured by interlaminar fracture and by
low-velocity impact tests. The geometry and the lay-up sequence of specimens are designed to probe various conditions such
as the skewness parameter, beam volume, and test fixture. The effect of interfacial ply orientations and crack propagation
directions on interlaminar fracture toughness and the effect of ply orientations and thickness on impact behavior are examined.
The critical strain energy release rate was calculated from the respective tests: in the interlaminar fracture test, the compliance
method and linear beam theory are used; the residual energy calculated from the impact test and the total delamination area
estimated by ultrasonic inspection are used in the low-velocity impact test. Results show that the critical strain energy
release rate is affected mainly by ply orientations. The critical strain energy release rate measured by the low-velocity
impact test lies between the mode I and mode II critical strain energy release rates obtained by the interlaminar fracture
test.
Submitted to the 11th International Conference on Mechanics of Composite Materials (Riga, June 11–15, 2000).
Published in Mekhanika Kompozitnykh Materialov, Vol. 36, No. 2, pp. 195–214, March–April, 2000. 相似文献