2,708 research outputs found
Innovation and Internationalization of Korean SMEs in the Textile and Footwear Industries
Innovation has been recognized as one of the factors that enhances firm internationalization, a vital route for the growth and survival of small and medium enterprises. Thus, it is important to identify antecedents of firm innovation and their impacts on SME internationalization for their long-term success. Accordingly, the present study examined a model of SME internationalization in which the causal relationships among entrepreneurial orientation, absorptive capacity, innovation (product, process, and marketing innovation), and internationalization were proposed. Analyses of 156 survey data collected from Korean SMEs exporting textiles, apparel, and footwear revealed that entrepreneurial orientation and absorptive capacity appeared to function as significant antecedents of product and process innovation. Among three dimensions of innovation, only process and marketing innovation positively affected internationalization. The study provides practical implications by asserting the importance of process and marketing innovation to increase firm internationalization
High-Performance PVC Gel for Adaptive Micro-Lenses with Variable Focal Length.
This paper presents a bio-inspired adaptive micro-lens with electrically tunable focus made of non-ionic high-molecular-weight polyvinyl chloride (PVC) gel. The optical device mimics the design of the crystalline lens and ciliary muscle of the human eye. It consists of a plano-convex PVC gel micro-lens on Indium Tin Oxide (ITO) glass, confined with an annular electrode operating as an artificial ciliary muscle. Upon electrical activation, the electroactive adhesive force of the PVC gel is exerted on the annular anode electrode, which reduces the sagittal height of the plano-convex PVC gel lens, resulting in focal length variation of the micro-lens. The focal length increases from 3.8 mm to 22.3 mm as the applied field is varied from 200 V/mm to 800 V/mm, comparable to that of the human lens. The device combines excellent optical characteristics with structural simplicity, fast response speed, silent operation, and low power consumption. The results show the PVC gel micro-lens is expected to open up new perspectives on practical tunable optics
Sequential whole cell conversion process for production of D-psicose and D- mannitol from D-fructose
Rare sugars, which exist only limited quantities naturally, have received considerable attention because of its various specific nutritional and biological functions. Likewise, D-psicose (D-ribo-2-hexulose or D-allulose), a C-3 epimer of D-fructose, has many uses which include reducing intra-abdominal fat accumulation, protecting pancreas beta-islets and improving insulin sensitivity. Especially, D-psicose has only 0.3% calories compared to sucrose, while it has 70% relative sweetness. Additionally, in 2012, D-psicose was approved as a food additive and designated as Generally Recognized As Safe (GRAS) by Food and Drug Administration (FDA). Despite such abundant advantages, there is no economical way of mass production of D-psicose. Recently, biological production of D-psicose from D-fructose using D-psicose 3-epimerase (DPE) has been developed. However, the conversion yield is below 30%, which causes an undesirable increase of purification cost because of the similar solubility of D-psicose and D-fructose. Thus, we addressed the problem by converting the residual fructose, after the reaction of D-psicose production, to D-mannitol, which has a low solubility. The sequential whole cell conversion reactions for D-psicose and D-mannitol allow a convenient and economic purification of both products. This work was supported by a grant from the Next-Generation BioGreen 21 Program (SSAC, grant#: PJ01106201), RDA, Korea.
Reference
1) Carsten Bäumchen & Stephanie Bringer-Meyer (2007), Expression of glf Z.m. increases D-mannitol formation in whole cell biotransformation with resting cells of Corynebacterium glutamicum, Appl Microbiol Biotechnol 76(3):545–52.
2) Ortiz, M. E., Bleckwedel, J., Raya, R. R., & Mozzi, F. (2013). Biotechnological and in situ food production of polyols by lactic acid bacteria, Appl Microbiol Biotechnol 97:4713-4726
3) Park, Y., Oh, E. J., Jo, J., Jin, Y., & Seo, J. (2016). Recent advances in biological production of sugar alcohols. Curr Opin Biotechnol 37:105–113
Age-dependent resistance of a perennial herb, Aristolochia contorta against specialist and generalist leaf-chewing herbivores
Plants need to balance investments in growth and defense throughout their life to increase their fitness. To optimize fitness, levels of defense against herbivores in perennial plants may vary according to plant age and season. However, secondary plant metabolites often have a detrimental effect on generalist herbivores, while many specialists have developed resistance to them. Therefore, varying levels of defensive secondary metabolites depending on plant age and season may have different effects on the performance of specialist and generalist herbivores colonizing the same host plants. In this study, we analyzed concentrations of defensive secondary metabolites (aristolochic acids) and the nutritional value (C/N ratios) of 1st-, 2nd- and 3rd-year Aristolochia contorta in July (the middle of growing season) and September (the end of growing season). We further assessed their effects on the performances of the specialist herbivore Sericinus montela (Lepidoptera: Papilionidae) and the generalist herbivore Spodoptera exigua (Lepidoptera: Noctuidae). Leaves of 1st-year A. contorta contained significantly higher concentrations of aristolochic acids than those of older plants, with concentrations tending to decrease over the first-year season. Therefore, when first year leaves were fed in July, all larvae of S. exigua died and S. montela showed the lowest growth rate compared to older leaves fed in July. However, the nutritional quality of A. contorta leaves was lower in September than July irrespective of plant age, which was reflected in lower larval performance of both herbivores in September. These results suggest that A. contorta invests in the chemical defenses of leaves especially at a young age, while the low nutritional value of leaves seems to limit the performance of leaf-chewing herbivores at the end of the season, regardless of plant age
Leaching kinetics of copper from waste printed circuit boards by electro-generated chlorine in HCl solution
The leaching behavior of metals such as copper, zinc, lead and tin from waste printed circuit boards (PCBs) has been investigated using electro-generated chlorine in hydrochloric acid solution. The experiments were carried out by employing two different reactors: (a) a combined reactor facilitated with simultaneous Cl2 generation and metal leaching, and (b) a separate metal leaching reactor connected with the anode compartment of a Cl2 gas generator. Leaching efficiency in two reactors was compared for recycling of valuable metals from the PCBs. It was observed that the leaching rate of the metals increased with increase in current density, temperature and time in both reactors. The copper leaching rate gradually diminished when its dissolution was around 20 and 25% in the combined and separate reactor, respectively, which may be attributed to a decrease in surface area of copper with leaching time and the formation of CuCl(s) on the surface. The leaching efficiency of copper was found to be lower in the combined reactor than that of the separate reactor. The dissolution kinetics of copper with electro-generated chlorine followed empirical logarithmic law controlled by surface layer diffusion. The leaching mechanism of copper was further corroborated by SEM-EDS study of the residue. The activation energy for copper leaching in the combined and separate reactors was calculated to be 24.5 and 20.7 kJ/mol, respectively in the temperature range 298–323 K
Mesenchymal Stem Cell-Extracellular Vesicle Therapy for Stroke: Scalable Production and Imaging Biomarker Studies
A major clinical hurdle to translate MSC-derived extracellular vesicles (EVs) is the lack of a method to scale-up the production of EVs with customized therapeutic properties. In this study, we tested whether EV production by a scalable 3D-bioprocessing method is feasible and improves neuroplasticity in animal models of stroke using MRI study. MSCs were cultured in a 3D-spheroid using a micro-patterned well. The EVs were isolated with filter and tangential flow filtration and characterized using electron microscopy, nanoparticle tracking analysis, and small RNA sequencing. Compared to conventional 2D culture, the production-reproduction of EVs (the number/size of particles and EV purity) obtained from 3D platform were more consistent among different lots from the same donor and among different donors. Several microRNAs with molecular functions associated with neurogenesis were upregulated in EVs obtained from 3D platform. EVs induced both neurogenesis and neuritogenesis via microRNAs (especially, miR-27a-3p and miR-132-3p)-mediated actions. EV therapy improved functional recovery on behavioral tests and reduced infarct volume on MRI in stroke models. The dose of MSC-EVs of 1/30 cell dose had similar therapeutic effects. In addition, the EV group had better anatomical and functional connectivity on diffusion tensor imaging and resting-state functional MRI in a mouse stroke model. This study shows that clinical-scale MSC-EV therapeutics are feasible, cost-effective, and improve functional recovery following experimental stroke, with a likely contribution from enhanced neurogenesis and neuroplasticity
Assessment of genetic diversity and distance of three Cicuta virosa populations in South Korea
Cicuta virosa L. (Apiaceae) is a perennial emergent plant designated as an endangered species in South Korea. Accordingto the former records, only four natural habitats remain in South Korea. A former study suggested that three of four popu-lations (Pyeongchang: PC, Hoengseong: HS, Gunsan: GS) would be classified as different ecotypes based on their differentmorphological characteristics and life cycle under different environmental conditions. To evaluate this suggestion, weestimated genetic diversity in each population and distance among three populations by random amplification of poly-morphic DNA. Seven random primers generated a total of 61 different banding positions, 36 (59%) of them were polymor-phic. Neis gene diversity and the Shannon diversity index increased in the order of PC < HS < GS, which is the same orderof population size. In the two-dimensional (2D) plot of first two principal components in principal component analysiswith the presence of 61 loci, individuals could be grouped as three populations easily (proportion of variance = 0.6125).Neis genetic distance for the three populations showed the same tendency with the geographical distance within threepopulations. And it is also similar to the result of discriminant analysis with the morphological or life-cycle factors fromthe previous study. From the results, we concluded that three different populations of C. virosa should be classified asecotypes based on not only morphology and phenology but genetic differences in terms of diversity and distance as well.This study was supported by the Korea Ministry of En-vironment as The Eco-Innovation project, 416-111-010and by the Center for Aquatic Ecosystem Restoration(CAER) of the Eco-STAR project from the Ministry of En-vironment, Republic of Korea (MOE;08-III-12).OAIID:oai:osos.snu.ac.kr:snu2013-01/102/0000026049/7SEQ:7PERF_CD:SNU2013-01EVAL_ITEM_CD:102USER_ID:0000026049ADJUST_YN:NEMP_ID:A075900DEPT_CD:719CITE_RATE:0FILENAME:07_ecoenv_36(3)_jae geun kim_(205-210).pdfDEPT_NM:생물교육과EMAIL:[email protected]:
Improved Surgical Technique for Heterotopic Aortic Transplantation in Mice
Transplant arteriosclerosis is the main limitation for long-term survival of solid organ transplant recipients. Animal models would provide invaluable tools to investigate the cellular and molecular mechanisms underlying the pathogenesis of transplant arteriosclerosis, as well as for studies with novel drugs and other reagents for the prevention of the disease. We have therefore developed a modified technique for aortic transplantation in mice. The central suture ligation of the recipient abdominal aorta allowed a simpler end-to-side anastomosis of a segment of the donor thoracic aorta into the infrarenal portion of the recipient abdominal aorta. Using this technique, the overall survival rate was 94%. We also observed typical aspects of chronic rejection of the aortic allografts not observed with isografts. Our new technique is relatively easy to perform and has a low incidence of thrombosis, thus being useful for studying various aspects of transplant arteriosclerosis
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