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141.
Yun Kwon Seong-Hwan Kim Yoonho Shin Munhyung Bae Byung-Yong Kim Sang Kook Lee Ki-Bong Oh Jongheon Shin Dong-Chan Oh 《Marine drugs》2014,12(4):2326-2340
Three new secondary metabolites, amycofuran (1), amycocyclopiazonic acid (2), and amycolactam (3), were isolated from the sponge-associated rare actinomycete Amycolatopsis sp. Based on combined spectroscopic analyses, the structures of 1–3 were determined to be a new benzofuran glycoside and new indole alkaloids related to cyclopiazonic acids, a class that has previously only been reported in fungi. The absolute configurations of 1 and 3 were deduced by ECD calculations, whereas that of 2 was determined using the modified Mosher method. Amycolactam (3) displayed significant cytotoxicity against the gastric cancer cell line SNU638 and the colon cancer cell line HCT116. 相似文献
142.
Yogesh Kumar Soon Jae Kwon Clarice J. Coyne Jinguo Hu Michael A. Grusak Theodore J. Kisha Rebecca J. McGee Ashutosh Sarker 《Genetic Resources and Crop Evolution》2014,61(5):965-977
The effective utilization of crop diversity held in genebanks depends on our knowledge of useful traits and available markers associated with the target traits. Target region amplification polymorphism (TRAP) was used to evaluate the genetic diversity and underlying relationships among 263 accessions of chickpea landraces maintained by the USDA-ARS Western Regional Plant Introduction Station in Pullman, WA, USA. Two-hundred sixty-two TRAP markers were amplified by eight primer combinations. Altogether, 110 (42 %) markers were polymorphic, the other 152 (58 %) displayed no variation. These polymorphic markers revealed important differences among the accessions, with an estimated, mean pair-wise genetic distance of 25.82 %, ranging from 2.8 to 50.0 %. Genetic distance analysis divided the accessions into two major groups, with 113 and 150 accessions each, and substantial association between molecular diversity and geographic origin was evident. Bayesian analysis of population structure revealed two groups (K = 2) with evidence for six sub-groups. Additionally, the population structure of a subset of 110 lines was determined (K = 3) for testing marker-trait associations (MTAs). Phenotypic traits included the concentrations of protein and nine mineral elements in the seeds. Two MTAs were significant (p < 0.01) for concentrations of Ca and K, and three MTAs were significant for Cu and Ni concentrations. The results indicate that this population is useful for genome-wide association studies on other economic traits given the level of genetic diversity uncovered and the marker-trait associations in seed minerals discovered. 相似文献
143.
Doo Hyun Baik Hae Young Kim Sun Jin Kwon Myung Hyun Kwon Han Sup Lee Ji Ho Youk Seung Won Seo 《Fibers and Polymers》2006,7(4):367-371
Thermal properties of copolyetherester/silica nanocomposites were examined by using DSC and TGA. The segmented block copolyetheresters
with various hard segment structures and hard segment contents (HSC) were synthesized and their silica nanocomposite films
were prepared by solution casting method. The nano-sized fumed silica particles were found to act as a nucleating agent of
the copolyetheresters. The nanocomposites always showed reduced degree of supercooling or faster crystallization than the
corresponding copolyetheresters. The nanocomposites also showed increased hard segment crystallinity except HSC 35 sample
which had short hard segment length. In case of 2GT [poly(ethylene terephthalate)] copolyetheresters, which were not developed
commercially because of their low crystallization rate, the hard segment crystallinity increased considerably. The copolyetherester/silica
nanocomposites showed better thermal stability than copolyetheresters. 相似文献
144.
Residual stresses were predicted by a flow analysis in the mold cavity and residual stress distribution in the injection molded
product was measured. Flow field was analyzed by the hybrid FEM/FDM method, using the Hele Shaw approximation. The Modified
Cross model was used to determine the dependence of the viscosity on the temperature and the shear rate. The specific volume
of the polymer melt which varies with the pressure and temperature fields was calculated by the Tait’s state equation. Flow
analysis results such as pressure, temperature, and the location of the liquid-solid interface were used as the input of the
stress analysis. In order to calculate more accurate gap-wise temperature field, a coordinate transformation technique was
used. The residual stress distribution in the gap-wise direction was predicted in two cases, the free quenching and the constrained
quenching, under the assumption that the shrinkage of the injection molded product occurs within the mold cavity and that
the solid polymer is elastic. Effects of the initial flow rate, packing pressure, and mold temperature on the residual stress
distribution was discussed. Experimental results were also obtained by the layer removal method for molded polypropylene. 相似文献
145.
Seasonal variations of fatty acids in various Korean shellfish were investigated in relation to the changes in total fatty acids contents, the ratio of polyunsaturated fatty acids to saturated fatty acids (P/S), and that of n-3 fatty acids to n-6 fatty acids (n-3/n-6). A distinct seasonal pattern was found in total fatty acids contents with maximal values in early summer and minimal values in late summer. The percentage of monounsaturated fatty acids was lowest in most species throughout the year. In summer months, the proportion of polyunsaturated fatty acids decreased while that of saturated fatty acids increased. The major contributing factor to the seasonal variation of polyunsaturated fatty acids was n-3 fatty acids. These results led to the lowest levels of P/S and n-3/n-6 in summer. Nevertheless, the data suggest that bivalve shellfish would be excellent sources of n-3 fatty acids, especially eicosapentaenoic acid and docosahexaenoic acid. 相似文献
146.
Oh-Jin Kwon Seung-Taek Oh Sang-Do Lee Na-Ri Lee Chang-Hoon Shin Jong-Shin Park 《Fibers and Polymers》2007,8(4):347-355
Hydrophilic and flexible polyurethane foams were prepared using sodium alginate as a polyol, and characterized by optical
microscopy, FT-IR spectroscopy, density measurements, volume swelling, and water absorbency. Optical microscopy revealed that
the resulting cells were closed with round and elongated shapes. FT-IR confirmed that the urethane linkages were formed between
the isocyanate and sodium-alginate. As an indirect measurement of porosity, the apparent density indicated an initial decrease
followed by an increase with increasing glycerin content. The volume-swelling ratio was initially constant, followed by a
gradual decrease with glycerin content. The volume swelling ratio increased with PEG molecular weight. The water absorbency
initially increased, followed by a decrease with increasing glycerin content. The correlation-ships between water absorbency,
density, and volume-swelling ratio indicated that the absorbency was predominantly influenced by density when the PEG molecular
weight was low and was greatly affected by the volume-swelling ratio when the PEG molecular weight was relatively high. 相似文献
147.
Apostolidis E Karayannakidis PD Kwon YI Lee CM Seeram NP 《Plant foods for human nutrition (Dordrecht, Netherlands)》2011,66(4):313-319
Ascophyllum nodosum is a brown seaweed that grows abundantly in the US Northeast coastal region. This study examined the seasonal variation of
A. nodosum in phenolic contents and subsequent antioxidant, α-glucosidase and α-amylase inhibitory activities. A. nodosum was harvested monthly and extracted in hot water and the resulting extracts were spray-dried. The results indicate a clear
seasonal variation in terms of phenolic content, with June and July being the highest (36.4 and 37 mg/g, respectively) and
May the lowest (21.8 mg/g). The antioxidant activities, in terms of 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging
activity, correlated with the phenolic contents observed (r = 0.81), with the month of July being the highest (58%) and April the lowest (26%). Similarly in terms of Trolox equivalent,
July had the highest activity (15.53 μM) and April and May the lowest (8.40 and 8.27 μM, respectively). α-glucosidase inhibitory
activity exhibited a pattern similar to the phenolic contents observed with July having the highest inhibitory activity (IC70 2.23 μg) and April the lowest (IC70 26.13 μg), resulting in an inverse correlation between IC70 values and total phenolic content (r = −0.89). Such seasonal variation is believed to be caused by temperature-related stress considering that A. nodosum is a cold water species. 相似文献
148.
Wei-Guo Zhao Jong-Wook Chung Soon-Wook Kwon Jeong-Heui Lee Kyung-Ho Ma Yong-Jin Park 《Euphytica》2013,191(1):9-21
Improvement of rice eating quality is an important objective in current breeding programs. In this study, 130 rice accessions of diverse origin were genotyped using 170 SSR markers to identify marker–trait associations with physicochemical traits on eating quality. Analysis of population structure revealed four subgroups in the population. Linkage disequilibrium (LD) patterns and distributions are of fundamental importance for genome-wide mapping associations. The mean r 2 value for all intrachromosomal loci pairs was 0.0940. LD between linked markers decreased with distance. Marker–trait associations were investigated using the unified mixed-model approach, considering both population structure (Q) and kinship (K). In total, 101 marker–trait associations (p < 0.05) were identified using 52 different SSR markers covering 12 chromosomes. The results suggest that association mapping in rice is a viable alternative to quantitative trait loci mapping, and detection of new marker–trait associations associated with rice eating quality will also provide important information for marker-assisted breeding and functional analysis of rice grain quality. 相似文献
149.
Sekkarapatti Ramasamy Madeshwaran Jin Kyoung Kwon Jae Whan Cho 《Fibers and Polymers》2013,14(2):182-187
Multi-walled carbon nanotubes (MWCNTs) were functionalized with hyperbranched aromatic polyamide (HAP) by in situ polymerization and by the AB 2 approach to enhance the mechanical properties of poly(methylmethacrylate) (PMMA) composites. Various concentrations of HAP-functionalized MWCNTs (HAP-f-MWCNTs) were used to prepare HAP-f-MWCNT-reinforced PMMA composite films. The covalent attachment of HAP to the MWCNTs, as achieved by in situ functionalization, resulted in effective dispersion of the MWCNTs in the PMMA matrix, thus enhancing the mechanical and thermal properties of the composite films. The breaking stress of the composites increased largely with the HAP-f-MWCNT loading. 相似文献
150.
Kang-Seuk Choi Soo-Jeong Kye Woo-Jin Jeon Mi-Ja Park Saeromi Kim Hee-Jung Seul Jun-Hun Kwon 《Journal of veterinary science (Suw?n-si, Korea)》2013,14(3):291-297
A recombinant hemagglutinin-neuraminidase (rHN) protein from Newcastle disease virus (NDV) with hemagglutination (HA) activity was expressed in Spodoptera frugiperda cells using a baculovirus expression system. The rHN protein extracted from infected cells was used as an antigen in a hemagglutination inhibition (HI) test for the detection and titration of NDV-specific antibodies present in chicken sera. The rHN antigen produced high HA titers of 213 per 25 µL, which were similar to those of the NDV antigen produced using chicken eggs, and it remained stable without significant loss of the HA activity for at least 12 weeks at 4℃. The rHN-based HI assay specifically detected NDV antibodies, but not the sera of other avian pathogens, with a specificity and sensitivity of 100% and 98.0%, respectively, in known positive and negative chicken sera (n = 430). Compared with an NDV-based HI assay, the rHN-based HI assay had a relative sensitivity and specificity of 96.1% and 95.5%, respectively, when applied to field chicken sera. The HI titers of the rHN-based HI assay were highly correlated with those in an NDV-based HI assay (r = 0.927). Overall, these results indicate that rHN protein provides a useful alternative to NDV antigen in HI assays. 相似文献