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Search Results: 1 - 10 of 3820 matches for " Joon-Woo Ahn "
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Serpin genes AtSRP2 and AtSRP3 are required for normal growth sensitivity to a DNA alkylating agent in Arabidopsis
Joon-Woo Ahn, Brian J Atwell, Thomas H Roberts
BMC Plant Biology , 2009, DOI: 10.1186/1471-2229-9-52
Abstract: Six Arabidopsis genes encoding full-length serpins were differentially expressed in developing seedlings and mature tissues. Basal levels of AtSRP2 (At2g14540) and AtSRP3 (At1g64030) transcripts were highest in reproductive tissues. AtSRP2 was induced 5-fold and AtSRP3 100-fold after exposure of seedlings to low concentrations of methyl methanesulfonate (MMS), a model alkylating reagent that causes DNA damage. Homozygous T-DNA insertion mutants atsrp2 and atsrp3 exhibited no differential growth when mutant and wild-type plants were left untreated or exposed to γ-radiation or ultraviolet light. In contrast, atsrp2 and atsrp3 plants exhibited greater root length, leaf number and overall size than wild-type plants when exposed to MMS. Neither of the two serpins was required for meiosis. GFP-AtSRP2 was localized to the nucleus, whereas GFP-AtSRP3 was cytosolic, suggesting that they target different proteinases. Induction of cell cycle- and DNA damage-related genes AtBRCA1, AtBARD1, AtRAD51, AtCYCB1;1 and AtCYCD1;1, but not AtATM, was reduced relative to wild-type in atsrp2 and atsrp3 mutants exposed to MMS.Expression of specific serpin genes (AtSRP2 and AtSRP3 in Arabidopsis) is required for normal responses of plants following exposure to alkylating genotoxins such as MMS.DNA damage results from exposure to specific chemicals in the environment, UV light, ionizing radiation and errors in DNA replication and proofreading. Plants utilize several pathways for DNA repair, including photoreactivation, nucleotide excision repair, base excision repair, mismatch repair and double-stranded break repair [1]. Methyl methanesulfonate (MMS) is a simple, direct alkylating agent recognized as a standard for genotoxicity assays of environmental pollutants [2]. MMS has been widely utilized as a γ-radiation mimic in the belief it causes double-stranded breaks (DSBs). A recent report found, however, that no MMS-mediated DSBs could be detected in vivo in yeast or mammalian cells, and thos
Serpins in rice: protein sequence analysis, phylogeny and gene expression during development
Francis Sheila E,Ersoy Renan A,Ahn Joon-Woo,Atwell Brian J
BMC Genomics , 2012, DOI: 10.1186/1471-2164-13-449
Abstract: Background Most members of the serpin family of proteins are potent, irreversible inhibitors of specific serine or cysteine proteinases. Inhibitory serpins are distinguished from members of other families of proteinase inhibitors by their metastable structure and unique suicide-substrate mechanism. Animal serpins exert control over a remarkable diversity of physiological processes including blood coagulation, fibrinolysis, innate immunity and aspects of development. Relatively little is known about the complement of serpin genes in plant genomes and the biological functions of plant serpins. Results A structurally refined amino-acid sequence alignment of the 14 full-length serpins encoded in the genome of the japonica rice Oryza sativa cv. Nipponbare (a monocot) showed a diversity of reactive-centre sequences (which largely determine inhibitory specificity) and a low degree of identity with those of serpins in Arabidopsis (a eudicot). A new convenient and functionally informative nomenclature for plant serpins in which the reactive-centre sequence is incorporated into the serpin name was developed and applied to the rice serpins. A phylogenetic analysis of the rice serpins provided evidence for two main clades and a number of relatively recent gene duplications. Transcriptional analysis showed vastly different levels of basal expression among eight selected rice serpin genes in callus tissue, during seedling development, among vegetative tissues of mature plants and throughout seed development. The gene OsSRP-LRS (Os03g41419), encoding a putative orthologue of Arabidopsis AtSerpin1 (At1g47710), was expressed ubiquitously and at high levels. The second most highly expressed serpin gene was OsSRP-PLP (Os11g11500), encoding a non-inhibitory serpin with a surprisingly well-conserved reactive-centre loop (RCL) sequence among putative orthologues in other grass species. Conclusions The diversity of reactive-centre sequences among the putatively inhibitory serpins of rice point to a range of target proteases with different proteolytic specificities. Large differences in basal expression levels of the eight selected rice serpin genes during development further suggest a range of functions in regulation and in plant defence for the corresponding proteins.
Distributed Sensor Network Based on RFID System for Localization of Multiple Mobile Agents  [PDF]
Byoung-Suk Choi, Joon-Woo Lee, Ju-Jang Lee, Kyoung-Taik Park
Wireless Sensor Network (WSN) , 2011, DOI: 10.4236/wsn.2011.31001
Abstract: This paper presents a distributed wireless sensor network for multiple mobile agents localization. Localization of mobile agents, such as mobile robots, humans, and moving objects, in an indoor space is essential for robot-robot interaction (RRI) and human-robot interaction (HRI). The standard localization system, which is based on sensors installed in the robot body, is not suitable for multiple agents. Therefore, the concept of sensor network, which uses wireless sensors distributed in a specified space, is used in this study. By analyzing related studies, two solutions are proposed for the localization of mobile agents including humans: a new hardware system and a new software algorithm. The first solution focuses on the architectural design of the wireless sensor network for multiple agent localization. A passive RFID system is used, and then the architecture of the sensor network is adapted to suit the target system. The second solution centers on a localization algorithm based on the sensor network. The proposed localization algorithm improves the accuracy in the multiple agent localization system. The algorithm uses the displacement conditions of the mobile agents and the recognition changes between the RFID tags and RFID reader. Through experiments using a real platform, the usefulness of the proposed system is verified.
Effect of Variation in Voltage on the Synthesis of Ag Nanopowder by Pulsed Wire Evaporation
Joon-Woo Song,Dong-Jin Lee,Fikret Yilmaz,Soon-Jik Hong
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/792429
Abstract: Nanosized Ag particles were obtained in liquid medium, which is composed of deionized water and sodium hexametaphosphate, using pulsed wire evaporation within hundreds of microseconds from pure initial Ag wire (99.98%), with varying voltage. Changes in powder morphology and microstructure due to change in supply voltage was observed by FE-SEM and HR-TEM, and phase structure of powders was analyzed by XRD. The results revealed that average particle size slightly increased with increasing supply voltage without any impurity and oxide phase, which was explained in terms of addition of stabilizer into the coolant liquid. The experimental results also suggest that addition of sodium hexametaphosphate into the coolant liquid is good for enhancing the dispersibility property of silver nanopowders.
Negative pressure wound therapy for soft tissue injuries around the foot and ankle
Hyun-Joo Lee, Joon-Woo Kim, Chang-Wug Oh, Woo-Kie Min, Oog-Jin Shon, Jong-Keon Oh, Byung-Chul Park, Joo-Chul Ihn
Journal of Orthopaedic Surgery and Research , 2009, DOI: 10.1186/1749-799x-4-14
Abstract: Using a NPWT device, 16 patients were prospectively treated for soft tissue injuries around the foot and ankle. Mean patient age was 32.8 years (range, 3–67 years). All patients had suffered an acute trauma, due to a traffic accident, a fall, or a crush injury, and all had wounds with underlying tendon or bone exposure. Necrotic tissues were debrided before applying NPWT. Dressings were changed every 3 or 4 days and treatment was continued for 18.4 days on average (range, 11–29 days).Exposed tendons and bone were successfully covered with healthy granulation tissue in all cases except one. The sizes of soft tissue defects reduced from 56.4 cm2 to 42.9 cm2 after NPWT (mean decrease of 24%). In 15 of the 16 cases, coverage with granulation tissue was achieved and followed by a skin graft. A free flap was needed to cover exposed bone and tendon in one case. No major complication occurred that was directly attributable to treatment. In terms of minor complications, two patients suffered scar contracture of grafted skin.NPWT was found to facilitate the rapid formation of healthy granulation tissue on open wounds in the foot and ankle region, and thus, to shorten healing time and minimize secondary soft tissue defect coverage procedures.Tendon and/or bone exposure commonly occurs in the foot and ankle region after acute trauma [1]. The conventional treatment method used for these uncovered, open wounds in the foot and ankle is skin grafting after the formation of healthy granulation tissue by wet dressing [2]. However, the duration of treatment may be prolonged, and patients may experience severe pain during dressing changes [3]. Furthermore, it is difficult to form healthy granulation tissue by simple wet dressing, when a tendon, bone, or implant is exposed. Accordingly, free flap surgery is often required, which requires substantial effort and introduces the issue of donor site morbidity [4].Negative pressure wound therapy (NPWT) was first described by Argenta and Moryk
A Study on the Seismic Isolation Systems of Bridges with Lead Rubber Bearings  [PDF]
Woo-Suk Kim, Dong-Joon Ahn, Jong-Kook Lee
Open Journal of Civil Engineering (OJCE) , 2014, DOI: 10.4236/ojce.2014.44031
Abstract: This study consists of the development and presentation of example of seismic isolation system analysis and design for a continuous, 3-span, cast-in-place concrete box girder bridge. It is expected that example is developed for all Lead-Rubber Bearing (LRB) seismic isolation system on piers and abutments which placed in between super-structure and sub-structure. Design forces, displacements, and drifts are given distinctive consideration in accordance with Caltrans Seismic Design Criteria (2004). Most of all, total displacement\"\" on design for all LRBs case is reduced comparing with combined lead-rubber and elastomeric bearing system\"\" . Therefore, this represents substantial reduction in cost because of reduction of expansion joint. This presents a summary of analysis and design of seismic isolation system by energy mitigation with LRB on bridges.
A Study on Water Repellent Effectiveness of Natural Oil-Applied Soil as a Building Material  [PDF]
Jong-Kook Lee, Jee-Eun Lee, Seong-Cheol Park, Hee-Dong Cho, Hye-Woong Yoo, Young-Sang Kim, Seong-Ryong Ryu, Woo-Suk Kim, Dong-Joon Ahn
Open Journal of Civil Engineering (OJCE) , 2015, DOI: 10.4236/ojce.2015.51014
Abstract: This study was performed to investigate the water repellent effectiveness of natural oil-applied soil when it is used as a building material. Natural oil types such as olive oil, bean oil, perilla oil and linseed oil, which are being used for producing water repellent timber, are selected for the experiments. It is expected that perilla oil and in seed oil, which are drying oil types will have better water repellent effectiveness than the other types. For the evaluation of water repellence of natural oil-applied soil, a contact angle test was performed. A contact angle of water drop on various surface conditions were tested, and large differences were seen between the natural oil-applied soil and untreated soil. As a result, it is showed that all natural oil types have water repellent effectiveness. However, linseed oil, which is a drying oil type, shows an outstanding water repellent effectiveness value, while perila oil, which is also a drying oil type, shows the lowest value. Additionally, results show that there is no link between water repellent effectiveness and the number of applications of natural oil. Nevertheless, existing commercial water repellents show better performance than natural oil, and it is anticipated that the results of this study will provide essential information for further research to enhance the water repellent effectiveness of soil as a building material.
Clinical Features and Course of Ocular Toxocariasis in Adults
Seong Joon Ahn,Se Joon Woo ,Yan Jin,Yoon-Seok Chang,Tae Wan Kim,Jeeyun Ahn,Jang Won Heo,Hyeong Gon Yu,Hum Chung,Kyu Hyung Park,Sung Tae Hong
PLOS Neglected Tropical Diseases , 2014, DOI: 10.1371/journal.pntd.0002938
Abstract: Purpose To investigate the clinical features, clinical course of granuloma, serologic findings, treatment outcome, and probable infection sources in adult patients with ocular toxocariasis (OT). Methods In this retrospective cohort study, we examined 101 adult patients diagnosed clinically and serologically with OT. Serial fundus photographs and spectral domain optical coherence tomography images of all the patients were reviewed. A clinic-based case-control study on pet ownership, occupation, and raw meat ingestion history was performed to investigate the possible infection sources. Results Among the patients diagnosed clinically and serologically with OT, 69.6% showed elevated immunoglobulin E (IgE) levels. Granuloma in OT involved all retinal layers and several vitreoretinal comorbidities were noted depending on the location of granuloma: posterior pole granuloma was associated with epiretinal membrane and retinal nerve fiber layer defects, whereas peripheral granuloma was associated with vitreous opacity. Intraocular migration of granuloma was observed in 15 of 93 patients (16.1%). Treatment with albendazole (400 mg twice a day for 2 weeks) and corticosteroids (oral prednisolone; 0.5–1 mg/kg/day) resulted in comparable outcomes to patients on corticosteroid monotherapy; however, the 6-month recurrence rate in patients treated with combined therapy (17.4%) was significantly lower than that in patients treated with corticosteroid monotherapy (54.5%, P = 0.045). Ingestion of raw cow liver (80.8%) or meat (71.2%) was significantly more common in OT patients than healthy controls. Conclusions Our study discusses the diagnosis, treatment, and prevention strategies for OT. Evaluation of total IgE, in addition to anti-toxocara antibody, can assist in the serologic diagnosis of OT. Combined albendazole and corticosteroid therapy may reduce intraocular inflammation and recurrence. Migrating feature of granuloma is clinically important and may further suggest the diagnosis of OT. Clinicians need to carefully examine comorbid conditions for OT. OT may be associated with ingestion of uncooked meat, especially raw cow liver, in adult patients.
Direct momentum-resolved observation of one-dimensional confinement of externally doped electrons within a single subnanometre-scale wire
Inkyung Song,Dong-Hwa Oh,Ha-Chul Shin,Sung-Joon Ahn,Youngkwon Moon,Sun-Hee Woo,Hyoung Joon Choi,Chong-Yun Park,Joung Real Ahn
Physics , 2015, DOI: 10.1021/nl503558g
Abstract: Cutting-edge research in the band engineering of nanowires at the ultimate fine scale is related to the minimum scale of a nanowire-based device. The fundamental issue at the subnanometre scale is whether angle-resolved photoemission spectroscopy (ARPES) can be used to directly measure the momentum-resolved electronic structure of a single wire because of the difficulty associated with assembling single wire into an ordered array for such measurements. Here, we demonstrated that the one-dimensional (1D) confinement of electrons, which are transferred from external dopants, within a single subnanometre-scale wire (subnanowire) could be directly measured using ARPES. Convincing evidence of 1D electron confinement was obtained using two different gold subnanowires with characteristic single metallic bands that were alternately and spontaneously ordered on a stepped silicon template, Si(553). Noble metal atoms were adsorbed at room temperature onto the gold subnanowires while maintaining the overall structure of the wires. Only one type of gold subnanowires could be controlled using external noble metal dopants without transforming the metallic band of the other type of gold subnanowires. This result was confirmed by scanning tunnelling microscopy experiments and first-principles calculations. The selective control clearly showed that externally doped electrons could be confined within a single gold subnanowire. This experimental evidence was used to further investigate the effects of the disorder induced by external dopants on a single subnanowire using ARPES.
Capnography for Assessing Nocturnal Hypoventilation and Predicting Compliance with Subsequent Noninvasive Ventilation in Patients with ALS
Sung-Min Kim,Kyung Seok Park,Hyunwoo Nam,Suk-Won Ahn,Suhyun Kim,Jung-Joon Sung,Kwang-Woo Lee
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0017893
Abstract: Patients with amyotrophic lateral sclerosis (ALS) suffer from hypoventilation, which can easily worsen during sleep. This study evaluated the efficacy of capnography monitoring in patients with ALS for assessing nocturnal hypoventilation and predicting good compliance with subsequent noninvasive ventilation (NIV) treatment.
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