The preparation of polyurethane foam combined with pH-sensitive alginate/bentonite hydrogel for wound dressings     

Seung-Taek Oh  Woo-Ram Kim  Sung-Hoon Kim  Yong-Chan Chung  Jong-Shin Park 《Fibers and Polymers》2011,12(2):159-165

Polyurethane (PU) foam was combined with protein drug-loaded pH-sensitive alginate-bentonite hydrogel for wound dressings. Alginate is a linear copolymer composed of 1–4-linked β-D-mannuronic acid (M) and its c-5-epimer α-Lguluronic acid (G). The amount of (M) and (G) and their sequential distribution are varied depending on the alginate source. Soluble sodium alginate can become a hydrogel when cross-linked with divalent cations and has widespread applications in the food, drink, pharmaceutical and bioengineering industries. Recently, it has been also proposed as a biomaterial for drug delivery systems. Bentonites are the natural inorganic polymers consisting of a large proportion of expandable clay minerals with a three-layer structure such as montmorillonite, beidellite, nontronite, etc. They are important adjutants and supports for medical products, and they have many useful physicochemical, mechanical, and biological properties such as absence of toxicity, indifference to other raw materials, sorption, swelling, and complex formation properties. Alginate-bentonite hydrogels were prepared at concentration ratios of 10/0, 7/3, 5/5, 3/7. PU foams were prepared using hydrophilic polyols. We investigated the controlled release of a protein drug from PU foam combined with alginate-bentonite hydrogel at different pH values of 4.2, 5.2, 7.2, 8.2. The mechanical properties and cytotoxicity tests of this foam were also studied.  相似文献   

Transferable GaN layers grown on ZnO-coated graphene layers for optoelectronic devices     

Chung K  Lee CH  Yi GC 《Science (New York, N.Y.)》2010,330(6004):655-657

We fabricated transferable gallium nitride (GaN) thin films and light-emitting diodes (LEDs) using graphene-layered sheets. Heteroepitaxial nitride thin films were grown on graphene layers by using high-density, vertically aligned zinc oxide nanowalls as an intermediate layer. The nitride thin films on graphene layers show excellent optical characteristics at room temperature, such as stimulated emission. As one of the examples for device applications, LEDs that emit strong electroluminescence emission under room illumination were fabricated. Furthermore, the layered structure of a graphene substrate made it possible to easily transfer GaN thin films and GaN-based LEDs onto foreign substrates such as glass, metal, or plastic.  相似文献   

Coordinate control of oxidative stress tolerance,vegetative growth,and fungal pathogenicity via the AP1 pathway in the rough lemon pathotype of Alternaria alternata     

Siwy Ling Yang  Ching-Hsuan Lin  Kuang-Ren Chung 《Physiological and Molecular Plant Pathology》2009,74(2):100-110

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Characterisation of QoI‐resistant field isolates of Botrytis cinerea from citrus and strawberry     

Hideo Ishii  James Fountaine  Wen‐Hsin Chung  Masanori Kansako  Kumiko Nishimura  Kazuhito Takahashi  Michiyo Oshima 《Pest management science》2009,65(8):916-922

BACKGROUND: In 2004, field isolates of Botrytis cinerea Pers. ex Fr., resistant to strobilurin fungicides (QoIs), were first found in commercial citrus orchards in Wakayama Prefecture, Japan. Subsequently, QoI‐resistant isolates of this fungus were also detected in plastic strawberry greenhouses in Saga, Ibaraki and Chiba prefectures, Japan. Biological and molecular characterisation of resistant isolates was conducted in this study. RESULTS: QoI‐resistant isolates of B. cinerea grew well on PDA plates containing kresoxim‐methyl or azoxystrobin at 1 mg L^?1, supplemented with 1 mM of n‐propyl gallate, an inhibitor of alternative oxidase, whereas the growth of sensitive isolates was strongly suppressed. Results from this in vitro test were in good agreement with those of fungus inoculation tests in vivo. In resistant isolates, the mutation at amino acid position 143 of the cytochrome b gene, known to be the cause of high QoI resistance in various fungal pathogens, was found, but only occasionally. The heteroplasmy of cytochrome b gene was confirmed, and the wild‐type sequence often present in the majority of resistant isolates, indicating that the proportion of mutated cytochrome b gene was very low. CONCLUSION: The conventional RFLP and sequence analyses of PCR‐amplified cytochrome b gene are insufficient for molecular identification of QoI resistance in B. cinerea. Copyright © 2009 Society of Chemical Industry  相似文献   

Endurance of linear and cross-linked shape memory polyurethane under rigorous hydrolysis conditions     

Yong-Chan Chung  Jae Won Choi  Na Eun Choi  Byoung Chul Chun 《Fibers and Polymers》2009,10(5):576-582

Linear shape memory polyurethane (SMPU) copolymers synthesized from 4,4′-methylene bis(phenylisocyanate) (MDI), poly(tetramethyleneglycol) (PTMG), and 1,4-butanediol (BD), and cross-linked SMPU by glycerol were being tested under the severe hydrolysis conditions for the tensile mechanical properties and the shape memory effect for 6 months. Tensile mechanical properties and shape memory effect were not substantially decreased after 6 months of storage, and SMPU structure was not affected during the long-term hydrolysis test as evidenced by IR, DSC, contact angle, and viscosity. Hydrolysis test was important in proving the durability of SMPU before application of SMPU in aqueous surrounding.  相似文献   

A look from the inside: perspectives on the expansion of food assistance programs at Michigan farmers markets     

Rebecca Mino  Kimberly Chung  Dru Montri 《Agriculture and Human Values》2018,35(4):823-835

There has been a recent push to offer more food assistance programs at farmers markets. Yet, as more programs are developed for farmers markets, little input has been sought from those who are ultimately responsible for their implementation. This ethnographic study explores the experiences of farmers markets that have been early adopters of federal food assistance programs. Participant observation and in-depth interviews were used in six early-adopting markets to understand staff perspectives on the challenges and benefits of administering food assistance programs. The results show that even markets with strong organizational capacity experienced significant burdens while operating food assistance programs. In addition, most worried about the sustainability of these programs due to the level of resources needed for their support. The findings suggest that calls to expand food assistance programs to all farmers markets will continue to be met with challenges as many markets will not have the capacity to operate them. Targeting farmers markets with strong organizational capacity may increase the probability of successful implementation, but building the organizational capacity of farmers markets may be necessary for widespread adoption. The study has implications for other sectors of civil society that are increasingly taking on the work of providing government programs.  相似文献   

Identification of lactoferrin and glutamate receptor‐interacting protein 1 in bovine cervical mucus: A putative marker for oestrous detection          下载免费PDF全文

WY Lee  MH Park  KW Kim  H Song  KB Kim  CS Lee  NK Kim  JK Park  BC Yang  KB Oh  GS Im  HJ Chung 《Reproduction in domestic animals》2017,52(1):16-23

Accurate detection of oestrus is important for artificial insemination. The aim of this study was to identify oestrous‐specific bovine cervical mucus proteins that could be used to determine the optimal time for artificial insemination. Non‐oestrous and controlled internal drug release (CIDR)‐induced oestrous‐stage mucus proteins were purified and subjected to surface‐enhanced laser desorption/ionization time‐of‐flight mass spectrometry, sodium dodecyl sulphate polyacrylamide gel electrophoresis and MALDI‐TOF/TOF. Among differentially expressed proteins, lactoferrin (LF) and glutamate receptor‐interacting protein 1 (GRIP1) showed a twofold increase during the CIDR‐induced oestrous stage compared to the levels in non‐oestrous stage in bovine cervical mucus. The RT‐PCR, Western blotting and immunohistochemistry results showed that LF and GRIP1 expression was significantly increased during the oestrous stage in the uterus. This study demonstrated that bovine LF and GRIP1 exist during the oestrous stage, but not during the non‐oestrous stage, suggesting that cervical mucus LF and GRIP1 are useful oestrous detection markers in cattle.  相似文献   

Promising antidiabetic potential of fucoxanthin isolated from the edible brown algae Eisenia bicyclis and Undaria pinnatifida     

Hyun Ah Jung  Md. Nurul Islam  Chan Mee Lee  Hyong Oh Jeong  Hae Young Chung  Hee Chul Woo  Jae Sue Choi 《Fisheries Science》2012,78(6):1321-1329

In the present study, we investigated the antidiabetic potential of fucoxanthin via the inhibition of rat lens aldose reductase (RLAR), human recombinant aldose reductase (HRAR), advanced glycation end-product (AGE) formation, protein tyrosine phosphatase 1B (PTP1B), and α-glucosidase. Fucoxanthin displayed potent inhibitory activity against AGE formation and HRAR and RLAR activity. In addition, fucoxanthin showed potent inhibitory activity against PTP1B. However, it did not show α-glucosidase inhibitory activity below 200 μM. In addition, our kinetic study revealed that fucoxanthin competitively inhibited RLAR, while it showed mixed-type inhibition against PTP1B. In order to confirm enzyme inhibition, we predicted the 3D structure of PTP1B using Autodock 4.0 to simulate the binding of fucoxanthin. Docking simulation results demonstrated that three residues of PTP1B (Phe30, Phe52, and Gly183) interact with the two hydroxyl groups of fucoxanthin. In addition, the binding energy was negative (?7.66 kcal/mol), indicating that the three hydrogen bonds may stabilize the open form of the enzyme and potentiate tighter binding to the active site of PTP1B, resulting in more effective PTP1B inhibition. The results of the present study therefore clearly demonstrate the promising potential of fucoxanthin as a therapeutic intervention for the management of diabetes as well as diabetes-associated complications, which could be explored further.  相似文献   

Molecular identification and characterization of Tcmago and TcY14 in Taiwania (Taiwania cryptomerioides)     

Chen YR  Shaw JF  Chung MC  Chu FH 《Tree physiology》2007,27(9):1261-1271

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Solvent Retention Capacity Values in Relation to Hard Winter Wheat and Flour Properties and Straight‐Dough Breadmaking Quality     

Z. S. Xiao  S. H. Park  O. K. Chung  M. S. Caley  P. A. Seib 《Cereal Chemistry》2006,83(5):465-471

Solvent retention capacity (SRC) was investigated in assessing the end use quality of hard winter wheat (HWW). The four SRC values of 116 HWW flours were determined using 5% lactic acid, 50% sucrose, 5% sodium carbonate, and distilled water. The SRC values were greatly affected by wheat and flour protein contents, and showed significant linear correlations with 1,000‐kernel weight and single kernel weight, size, and hardness. The 5% lactic acid SRC value showed the highest correlation (r = 0.83, P < 0.0001) with straight‐dough bread volume, followed by 50% sucrose, and least by distilled water. We found that the 5% lactic acid SRC value differentiated the quality of protein relating to loaf volume. When we selected a set of flours that had a narrow range of protein content of 12–13% (n = 37) from the 116 flours, flour protein content was not significantly correlated with loaf volume. The 5% lactic acid SRC value, however, showed a significant correlation (r = 0.84, P < 0.0001) with loaf volume. The 5% lactic acid SRC value was significantly correlated with SDS‐sedimentation volume (r = 0.83, P < 0.0001). The SDS‐sedimentation test showed a similar capability to 5% lactic acid SRC, correlating significantly with loaf volume for flours with similar protein content (r = 0.72, P < 0.0001). Prediction models for loaf volume were derived from a series of wheat and flour quality parameters. The inclusion of 5% lactic acid SRC values in the prediction model improved R² = 0.778 and root mean square error (RMSE) of 57.2 from R² = 0.609 and RMSE = 75.6, respectively, from the prediction model developed with the single kernel characterization system (SKCS) and near‐infrared reflectance (NIR) spectroscopy data. The prediction models were tested with three validation sets with different protein ranges and confirmed that the 5% lactic acid SRC test is valuable in predicting the loaf volume of bread from a HWW flour, especially for flours with similar protein contents.  相似文献