Potential use of δ¹³C, δ¹⁵N, N concentration, and Ca/Al of Pinus densiflora tree rings in estimating historical precipitation pH     

Jin-Hyeob Kwak  Sang-Sun Lim  Scott X. Chang  Kye-Han Lee  Woo-Jung Choi 《Journal of Soils and Sediments》2011,11(5):709-721

Purpose  

The chemistry of annual tree growth rings is affected by precipitation pH, and tree rings store information on environmental conditions at the time of ring formation. The purpose of this study was to evaluate the potential use of tree ring chemistry data in estimating historical precipitation pH using the relationship between precipitation pH and tree ring chemistry.  相似文献   

Surface modification of silk fibroin nanofibrous mat with dextran for wound dressing     

Moo Kon Kim  Hyo Won Kwak  Hyung Hwan Kim  Tae Rin Kwon  So Young Kim  Beom Joon Kim  Young Hwan Park  Ki Hoon Lee 《Fibers and Polymers》2014,15(6):1137-1145

In this study, we examined the effects of a dextran-modified silk fibroin nanofibrous mat (D-SFNM) on wound healing. To increase the hydrophilicity of silk fibroin (SF), the SF nanofibrous mat (SFNM) was modified with oxidized dextran. The D-SFNM absorbed water faster than the SFNM, and the swelling ratio was increased by approximately 80 % compared with the SFNM. An in vitro cell (NIH3T3) test revealed that fewer cells attached to the D-SFNM than the SFNM, but the proliferation of cells was not significantly affected by the presence of dextran. An in vivo wound healing test with mice indicated that the D-SFNM resulted in a good wound recovery effect similar to a commercial wound dressing material. The increased hydrophilicity of the D-SFNM might balance the moist environment at the wound site, which improves the wound healing compared with the SFNM.  相似文献   

Positional signaling mediated by a receptor-like kinase in Arabidopsis     

Kwak SH  Shen R  Schiefelbein J 《Science (New York, N.Y.)》2005,307(5712):1111-1113

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Mechanical properties of wool fiber in the stretch breaking process   总被引：1，自引：0，他引：1  

Seung A Kwak  Jun Young Lee  Dae Hoon Lee  Boong Soo Jeon 《Fibers and Polymers》2007,8(1):130-133

Short wool fibers obtained by the stretch breaking process can be blended with cotton fibers and processed in a cotton spinning system, which has a high production rate. For the structural property of the wool fiber after stretch breaking, the diameter and length of the wool fiber were measured as a function of time. The diameter of the broken fibers was finer than the diameter of untreated fibers. The fiber diameter at the break point was the finest and was more irregular than the original fiber. The broken fiber showed mechanical properties of increased modulus, decreased breaking strain, and increased breaking strength.  相似文献   

Room temperature polymerization of N-vinylcarbazole in tetrahydrofuran     

Won?Seok?LyooEmail author  Jin?Woo?Kwak  Seok?Kyun?Noh  Dae?Heum?Kim  Jinwon?Lee  Nakjoong?Kim  Ki?Hong?Park  Chul?Joo?Lee 《Fibers and Polymers》2004,5(2):89-94

N-Vinylcarbazole (VCZ) was solution-polymerized in tetrahydrofuran (THF) at 25, 35, and 45 °C using a room temperature initiator, 2,2′-azobis(2,4-dimethylvaleronitrile) (ADMVN); the effects of amount of solvent, polymerization temperature, and initiator concentration were investigated. On the whole, the experimental results corresponded to predicted ones. Room polymerization temperature using ADMVN proved to be successful in obtaining poly(N-vinylcarbazole) (PVCZ) of high molecular weight with small temperature rise during polymerization, nevertheless of free radical polymerization by azoinitiator. The polymerization rate of VCZ in THF was proportional to the 0.47 power of ADMVN concentration. The molecular weight was higher and the molecular weight distribution was narrower with PVCZ polymerized at lower temperatures. For PVCZ prepared in THF at 25 °C using ADMVN concentration of 0.00005 mol/mol of VCZ, weight-average molecular weight of 221,000 was obtained, with polydispersity index of 2.05, and degree of lightness converged to about 99 %.  相似文献   

Kunitz-type serine protease inhibitor from potato (Solanum tuberosum L. cv. Jopung)     

Park Y  Choi BH  Kwak JS  Kang CW  Lim HT  Cheong HS  Hahm KS 《Journal of agricultural and food chemistry》2005,53(16):6491-6496

An antifungal protein, AFP-J, was purified from tubers of the potato (Solanum tuberosum cv. L Jopung) by various chromatographic columns. AFP-J strongly inhibited yeast fungal strains, including Candida albicans, Trichosporon beigelii, and Saccharomyces cerevisiae, whereas it exhibited no activity against crop fungal pathogens. Automated Edman degradation determined the partial N-terminal sequence of AFP-J to be NH2-Leu-Pro-Ser-Asp-Ala-Thr-Leu-Val-Leu-Asp-Gln-Thr-Gly-Lys-G lu-Leu-Asp-Ala-Arg-Leu-. The partially sequence had 83% homology with a serine protease inhibitor belonging to the Kunitz family, and the protein inhibited chymotrypsin, pepsin, and trypsin. Mass spectrometry showed that its molecular mass was 13 500.5 Da. This protease inhibitor suppressed over 50% the proteolytic activity at 400 microg/mL. These results suggest that AFP-J is an excellent candidate as a lead compound for the development of novel antiinfective agents.  相似文献   

Flexible VOC sensors using conductive polymers and porous membranes for application to textiles     

Taekyeong Kim  Dongsup Kwak 《Fibers and Polymers》2012,13(4):471-474

In order to fabricate textile-based flexible VOC sensors, two conductive polymers such as polyaniline and poly(3,4-ethylenedioxythiophene)-poly(styrene-sulfonate) (PEDOT:PSS) were used as VOC-sensing materials, and various porous organic membranes were used as base substrates on which the conductive polymers were coated. Electrical resistance change of conductive polymers by adsorption of VOCs was measured. Polyaniline showed better sensitivity than PEDOT:PSS. Porous high density polyethylene membrane exhibited the most stable signal reproducibility and dimensional stability of membrane itself. Even after covering with additional high density polyethylene membrane to protect conductive polyaniline inside, the stable signals were still obtained during repeated measurement.  相似文献   

Assessing vulnerability of forests to climate change in South Korea     

Guishan Cui  Hanbin Kwak  Sungho Choi  Moonil Kim  Chul-Hee Lim  Woo-Kyun Lee  Joon-Soon Kim  Yeora Chae 《林业研究》2016,27(3):489-503

This study demonstrated a framework to assess vulnerability of forests to climate change. We focused on how alterations of temperature and precipitation might affect forest type distributions and carbon-related functions. In particular, our framework considered three sectors of forest type distribution, net primary production, and soil carbon storage. Future projections were derived from mechanistic models for South Korean forests under the A1B scenarios of the intergovernmental panel on climate change. Forest type distributions were simulated by the Hydrological and thermal analogy group model, while the MAPSS and CENTURY1 models estimated forest carbon flux/storage. We quantified normalized vulnerability indices for each sector. Our results indicate that the overall vulnerability of forest type distribution is greater in the west central regions and southeastern inlands. The vulnerabilities of carbon flux/storage show that net primary production of South Korean forests is relatively less susceptible to climate change, but a highly vulnerable area of soil carbon storage mainly spreads from the west central to the south east region. The spatio-temporal vulnerability map with a synoptic overview from this study might be useful for policy makers in preparing adaptive measures and identifying management priorities.  相似文献   

Modelling riverine habitat for robust redhorse: assessment for reintroduction of an imperilled species     

J. M. Fisk II  T. J. Kwak  R. J. Heise 《Fisheries Management and Ecology》2014,21(1):57-67

A critical component of a species reintroduction is assessment of contemporary habitat suitability. The robust redhorse, Moxostoma robustum (Cope), is an imperilled catostomid that occupies a restricted range in the south‐eastern USA. A remnant population persists downstream of Blewett Falls Dam, the terminal dam in the Pee Dee River, North Carolina. Reintroduction upstream of Blewett Falls Dam may promote long‐term survival of this population. Tillery Dam is the next hydroelectric facility upstream, which includes a 30 rkm lotic reach. Habitat suitability indices developed in the Pee Dee River were applied to model suitable habitat for proposed minimum flows downstream of Tillery Dam. Modelling results indicate that the Tillery reach provides suitable robust redhorse habitat, with spawning habitat more abundant than non‐spawning habitat. Sensitivity analyses suggested that suitable water depth and substrate were limiting physical habitat variables. These results can inform decisions on flow regulation and guide planning for reintroduction of the robust redhorse and other species.  相似文献   

Population-specific QTLs and their different epistatic interactions for pod dehiscence in soybean [<Emphasis Type="Italic">Glycine max</Emphasis> (L.) Merr.]     

Sung-Taeg Kang  Myounghai Kwak  Hyeun-Kyeung Kim  Myoung-Gun Choung  Won-Young Han  In-Youl Baek  Moon Young Kim  Kyujung Van  Suk-Ha Lee 《Euphytica》2009,166(1):15-24

Pod dehiscence (PD) prior to harvest results in serious yield loss in soybean. Two linkage maps with simple sequence repeat (SSR) markers were independently constructed using recombinant inbred lines (RILs) developed from Keunolkong (pod-dehiscent) × Sinpaldalkong (pod-indehiscent) and Keunolkong × Iksan 10 (pod-indehiscent). These soybean RIL populations were used to identify quantitative trait loci (QTLs) conditioning resistance to PD. While a single major QTL on linkage group (LG) J explained 46% of phenotypic variation in PD in the Keunolkong × Sinpaldalkong population with four minor QTLs, three minor QTLs were identified in the Keunolkong × Iksan 10 population. Although these two populations share the pod dehiscent parent, no common QTL has been identified. In addition, epistatic interactions among three marker loci partially explained phenotypic variation in PD in both populations. The result of this study indicates that different breeding strategies will be required for PD depending on genetic background.  相似文献