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        검색결과 58

        21.
        2018.10 구독 인증기관·개인회원 무료
        To control an external parasitic mite, a honey bee line possessing high hygienic behavior (HHB) against an external parasitic mite, Varroa destructor, has been bred in South Korea and an assessment method has been necessitated to diagnose HHB line from the low hygienic behavior (LHB) line. Thus, in this study, we developed single nucleotide polymorphism (SNP) markers from whole genome sequencing of each 20 worker bees from HHB and LHB lines of A. mellifera ligustica (Hymenoptera: Apidae). An average of 319,445,977 sequence reads was mapped to the known A. mellifera reference genome (an average of 87.46%). In 2,316,128 and 3,266,756 SNPs from each HHB and LHB line, an average of 93.6% and was located in the intergenic spacers and introns, whereas, the remaining 6.4% was located in the genic region, respectively. Among them 20 SNPs that were fixed at each line possessing within-individual homozygosity were selected and each four SNPs were used to diagnose the two honey bee lines either by typical PCR-restriction fragment length polymorphism method or allele-specific PCR. The remaining six SNPs had the size difference, enabling relatively easy differentiation between the two honey bee lines on typical agarose gel and another remaining six SNPs only has sequence difference including SNP sites. Thus, these SNP markers can be used to diagnose the honey bee line with HHB from LHB line against V. destructor.
        22.
        2018.10 구독 인증기관·개인회원 무료
        Japanese pine sawyer beetle, Monochamus alternatus Hope (Coleoptera: Cerambycidae) is considered as a serious pest in pine trees. To develop an eco-friendly strategy to manage this forest insect, we collected entomopathogenic fungi from Korean soil and assessed their virulence against the adults of the insect in laboratory conditions. As a result, two isolates with conidial suspension (1.0×107conidia/ml), showed 87% and 90% mortality 12 days after fungal treatment, respectively. We assessed the potential of the fungi-derived destruxin and protease as additives to the fungal isolates, and they showed insecticidal activity via feeding and spraying treatments. Finally, we produced fungal conidia in massive solid cultures and formulated wettable powders, and now studying optimal conditions of oil-based formulation with two isolates. Based on these results, we are evaluating the control efficacy of the fungal agents against M. alternatus in field conditions.
        23.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Modern manufacturing industries is to produce both precise and robust mechanical parts without failure while they are in service. In order to prevent a part failure for its lifetime, a mechanical design for a part should be examined on a basis of mechanical simulation. A nozzle plate, being a key part in steam engines, changes flow directions of steam in a turbine used in power plant. This paper is to the design and test for part safety and durability. Currently, nozzle plates are fabricated by welding nozzles to their plates. Welding causes some defects on the used materials while they are being manufactured. Another major defect is un-even pitches between welded nozzles. Welding causes phase changes because of high melting temperature of metal. This leads to decay on the welding spots, which weakens their structural strength and then, may lead to early damages on mechanical structures. This research proposes assembly-typed nozzle plate without welding. From the beginning, nozzle and plate are designed for insertion-typed assembly. Nozzle head and foot are designed in accordance with the grooves on outer ring and inner ring of a plate to make mating surfaces. Then the nozzle plate should be proved for structural and fatigue safety before they are put in manufacturing. This research adopts commercial softwares for modeling and mechanical simulation. The test result shows that the design with smaller mating area and deeper insertion produces higher safety in terms of structure and durability. From the conclusion, this paper proposes the assembly-typed nozzle plate to replace the welding typed.
        4,000원
        24.
        2018.05 구독 인증기관·개인회원 무료
        Pavement performance usually depends on the pavement’s material property, traffic and environmental conditions. Current pavement design programs such as the Mechanistic Empirical Pavement Design Guide use these factors in assessing the pavement life and performance in terms of different distresses like rutting and fatigue cracking. Theoretically, the cracking and rutting behaviour of pavements are based on accumulated strains experienced by the pavement which is brought by the weight and loading speed of vehicles. A steady state loading device was used in the field to evaluate pavement deflection’s behaviour in varying loading frequencies. It was observed that the pavement deflection increases as the loading frequency also increases until it approaches a certain frequency wherein the deflection decreases thereafter. In this study, a three-dimensional finite element pavement model was established using ABAQUS wherein the effect of the vehicle’s loading frequencies was analysed. The calculated static deflection and stress from the finite element (FE) model were found to have good correlation with the KENPAVE measured deflection and stress. The deflections of different pavement conditions were further studied and analysed by generating several pavement geometries and strength from the FE model using a frequency sweep response analysis. It was found that the geometric condition and the current modulus of the pavement can amplify the pavement deflection by a factor, β, depending on the loading frequency. The peak deflection was found to be occurring when the loading frequency approaches one of the pavement’s natural frequencies. Based on the finding from this study, the natural frequency is an important factor to be considered in designing pavements. Further study is recommended to understand more on how to minimize the effect of natural frequency to pavement life.
        25.
        2018.04 구독 인증기관·개인회원 무료
        Japanese pine sawyer, Monochamus alternatus Hope (Coleoptera: Cerambycidae) in forest is considered as a serious forest pest in pine trees. In this study, we collected entomopathogenic fungi from soil and assessed their virulence against the adults of the inset using a spray method in laboratory condition. Two entomopathogeinc fungi isolates showed high virulence against the adults. In the concentration of 1.0 × 107conidia/ml, the mortality rate of the adults were 53% and 60%. In semi-field condition, one isolate showed a virulence of 60% against the adult. Consequently, we confirmed the possibility of the fungal isolates in controlling the beetles. In near the future, we will investigate several factors which is possibly related to the control of the forest insect pest using entomopathogenic fungi in field conditions, given the importance of fungal formulation and practical application methods.
        26.
        2017.10 구독 인증기관·개인회원 무료
        Chemical pesticides have been used for persimmon pest control, however the overuse caused insect resistance andenvironmental toxicity. Herein this work, we investigated the biological potential of eco-friendly organic pesticides (biologicals)and entomopathogenic fungi in controlling persimmon pests, Stathmopoda masinisaa and Riptortus pedetris. A botanicalmixture of Chinese scholar tree, goosefoot and subtripinnata extract, Bacillus thuringesis NT0423 and one isolate of Beauveriabassiana showed high insecticidal activity against the pests in laboratory conditions. The selected botanical extract andmicroorganism were combined with a chemical pesticide (buprofezin+dinotefuran WP) and were assessed their controlefficacy in persimmon fields. Compared to the three times of chemical spray, the combination of more than one timeof chemical spray and the selected biologicals controlled the persimmon pests with an acceptable levels. Consequentlyone time of biological spray can be integrated to the spray program where only chemicals are strongly considered.
        28.
        2017.04 구독 인증기관·개인회원 무료
        We developed single nucleotide polymorphism (SNP) markers and are establishing diagnostic systems to distinguish disease resistance- and susceptible-strains of honey bees using the SNPs. For development of SNP markers, whole genome was sequenced each from 20 individuals of “disease resistance-strain” and “susceptible-strain” of Apis mellifera ligustica using the Illumina HiSeq 2000 sequencer. Approximately, 344 and 294 million sequence reads were mapped to the honeybee reference assembly (Amel_4.5) for each strain, respectively. Among the total 2,246,428 SNPs yielded, 33 were found to be fixed between the two strains with all homozygosity. Sixteen of them were casually amplified and sequenced from randomly selected each 10 individual of honey bees from each strain and presented strain specific SNPs. These ten SNPs were used to diagnose the two strains either by original size difference, caused by indel-accompanying SNP, typical PCR-RFLP, or AS PCR.
        29.
        2017.04 구독 인증기관·개인회원 무료
        We sequenced the complete mitochondrial genome (mitogenome) of Vespa velutina nigrithorax and V. ducalis (Hymenoptera: Vespidae). The genomes were 16,475-bp and 15,779-bp long and contained typical sets of genes. The V. velutina and V. ducalis A+T-rich region was 132-bp long and 166-bp long and was the shortest of all sequenced Vespoidea genomes. Start and stop codons in several Vespa species—including V. velutina and V. ducalis—were diversified, despite these species belonging to the same genus. In comparison with the ancestral mitogenomes, Vespa mitogenomes showed substantial gene rearrangement; however, we detected no gene rearrangement among Vespa species. We conducted phylogenetic reconstruction based on concatenated sequences of 13 PCGs and two rRNAs in available species of Vespoidea—22 species in six subfamilies in two families (Vespidae and Formicidae). The Bayesian inference and maximum likelihood (ML) methods revealed that each family formed strong monophyletic groups.
        30.
        2017.04 구독 인증기관·개인회원 무료
        Entomopathogenic fungi are expected to play a role as great biological control agents in the global bio-pesticide market in the future. The first step is the collection of fungal isolates and it should be a platform for the development of highly effective biopesticides. In this work, we constructed a fungal library using a mealworm pathogenecity-based fungal collection method and further characterized some isolates with high virulence. A phylogenetic tree was generated, and of the isolates 17 isolates’ biological features were characterized, such as morphology, virulence against several insect, stability of conidia for heat, production of biologically active materials, such as enzymes. This work reports an attractive entomopathogenic fungal library including the information of effective isolates in pest management.
        32.
        2016.10 구독 인증기관·개인회원 무료
        Chemical pesticides have been used to control persimmon pests, however the overuse of the pesticides caused insect resistance. Herein we investigate the potential of eco-friendly organic pesticides (EFOP) on the control persimmon pests, Stathmopoda masinissa and Riptortus pedestris. Eleven commercially available EFOP were sprayed on the target insects in laboratory conditions. The chemical pesticide, buprofezin+dinotefuran wettable powder served as a positive control. In the bioassay against persimmon fruit moth, the mixture of Chinese scholar tree, goosefoot and subtripinnata extracts (EFOP-2) treatment showed the highest control efficacy: 27.7% (5 days) of survival rates. In the bioassay against bean bugs, the EFOP-2 showed the highest control efficacy: 20.0% (5 days) of survival rates. These results suggest that the mixture of three plants extracts (EFOP-2) has high and multiple potential in the management of the persimmon pests.
        33.
        2016.04 구독 인증기관·개인회원 무료
        The spotted-wing drosophila Drosophila suzukii (Diptera: Drosophilidae) is an Asian species introduced into North America and Europe. It damages a wide variety of thin-skinned fruits. We sequenced the complete mitochondrial genome (mitogenome) of D. suzukii to better understand the mitogenomic characteristics of this species and understand phylogentic relationships of Drosophila. The 16,230-bp complete mitogenome of the species consists of a typical set of genes, including 13 protein-coding genes (PCGs), two rRNA genes, and 22 tRNA genes, and one major non-coding A+T-rich region, with an arrangement typical of insects. Twelve PCGs began with the typical ATN codon, whereas the COI began with TCG, which has been designated as the start codon for other Drosophila species. The 1,525-bp A+T-rich region is the second longest in Drosophila species for which the whole mitogenome has been sequenced, after D. melanogaster. Phylogenetic analysis with the 13 PCGs of the Drosophila species using Bayesian Inference and Maximum likelihood methods both placed D. suzukii at the basal lineage of the previously defined Melanogaster group, with a strong support.
        34.
        2016.04 구독 인증기관·개인회원 무료
        Entomopathogenic fungi are facultative microorganisms, dwelling in soil or infecting host insects, and some of the genera have been used as biological control agents worldwide. Collection of fungal isolates should be a platform for the development of highly effective resources, thus in this work we constructed a fungal library using a mealworm (Tenebrio molitor) pathogenicity-based fungal collection method and further characterized some isolates with high virulence. A phylogenetic three was generated, and of the isolates 17 isolates’ biological features were characterized, such as morphology, spectrum of virulence, cultural characteristics, thermo-stability of fungi, production of biologically active materials, such as enzymes. This work reports an attractive entomopathogenic fungal library including the information of effective isolates in pest management.
        35.
        2015.10 구독 인증기관·개인회원 무료
        Entomopathogenic fungi are facultative microorganisms, dwelling in soil or infecting host insects, and some of the genera have been used as biological control agents worldwide. Collection of fungal isolates should be a platform for the development of highly effective resources, thus in this work we constructed a fungal library using a mealworm pathogenecity-based fungal collection method and further characterized some isolates with high virulence. A phylogenetic three was generated, and of the isolates 17 isolates’ biological features were characterized, such as morphology, spectrum of virulence, cultural characteristics, thermo-stability of fungi, production of biologically active materials, such as enzymes. This work reports an attractive entomopathogenic fungal library including the information of effective isolates in pest management.
        36.
        2015.04 구독 인증기관·개인회원 무료
        Entomopathogenic fungi are facultative microorganisms, dwelling in soil or infecting host insects, and some of the genera have been used as biological control agents worldwide. Collection of fungal isolates should be a platform for the development of highly effective resources, thus in this work we constructed a fungal library using a mealworm pathogenecity-based fungal collection method and further characterized some isolates with high virulence. A phylogenetic three was generated, and of the isolates 17 isolates’ biological features were characterized, such as morphology, spectrum of virulence, cultural characteristics, thermo-stability of fungi, production of biologically active materials, such as enzymes. This work reports an attractive entomopathogenic fungal library including the information of effective isolates in pest management.
        37.
        2013.04 구독 인증기관·개인회원 무료
        Mealworms, Tenebrio molitor (L.) is used as an important animal feed additive for growth promotion and health management, but potentially exposes to fungal infection. In this work, virulence of two species of entomopathogenic fungi against the insect, and the relationship between abiotic features and virulence were investigated. Secondly our consideration was also given to the effect of chemical fungicides on conidial germination for risk control. Between Beauveria bassiana (Bb) and Metarhizium roberstii (Mr) (previously M. anisopliae), Bb isolates had much higher virulence (~100% mortality in 3~4 days after the treatment), rather than Mr isolates in laboratory assays. Next, fungus-treated mealworms were kept at wheat bran at 20, 25, 30 and 35℃ with 3, 6, 9 times of water spray to the feeds for set-up of different humidity conditions. Inoculation of fungi to mealworms was conducted by fungal spray and feeding methods, which resulted in higher virulence in feeding method. In the feeding method, all temperature treatments except 35℃ showed high virulence against mealworms, but any significant relationship between virulence and humidity was not observed. In the chemical fungicide screening, fluazinam (CAS No. 79622-59-6) and mancozeb (8018-01-7) significantly inhibited the germination of Bb and Mr conidia. This work suggest that contamination of wheat bran with fungal pathogens, particularly B. bassiana may induce mycosis of mealworms, but introduction of effective fungicides possibly reduce fungal infection.
        38.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Methanol as a carbon source in chemical vapor deposition (CVD) graphene has an advantage over methane and hydrogen in that we can avoid optimizing an etching reagent condition. Since methanol itself can easily decompose into hydrocarbon and water (an etching reagent) at high temperatures [1], the pressure and the temperature of methanol are the only parameters we have to handle. In this study, synthetic conditions for highly crystalline and large area graphene have been optimized by adjusting pressure and temperature; the effect of each parameter was analyzed systematically by Raman, scanning electron microscope, transmission electron microscope, atomic force microscope, four-point-probe measurement, and UV-Vis. Defect density of graphene, represented by D/G ratio in Raman, decreased with increasing temperature and decreasing pressure; it negatively affected electrical conductivity. From our process and various analyses, methanol CVD growth for graphene has been found to be a safe, cheap, easy, and simple method to produce high quality, large area, and continuous graphene films.
        4,000원
        40.
        2012.06 구독 인증기관·개인회원 무료
        Acteoside acts as an anti-oxidative activity and anti-apoptosis in the cells. But, it has been not studied on maturation and development of porcine oocytes. The aims of the present study were to examine the effects of acteoside on the morphological progress of meiosis, developmental competence, and ROS in porcine oocytes. Oocytes were matured in tissue culture medium-199, supplemented with acteoside at various concentrations: 0 (control), 10, 30 and 50 μM. The oocytes maturation rates of groups supplemented with acteoside were no significantly different (81.13, 85.96, 82.95 and 83.68%, respectively). Level of ROS was significantly decreased in acteoside treated group. Furthermore, the parthenogenetic blastocyst rate was significantly improved in 10 μM acteoside treated group compared with control group (44.83 vs. 27.75%). And we investigated effect of acteoside on the oocytes condition represented by cytoplasmic maturation by homogeneous distribution and formation of cytoplasmic organelles and regulation of apoptosis-related genes. In the results. during IVM, 10 μM acteoside treated oocytes showed that the mitochondria and lipid droplet were smaller and homogeneous distribution in cytoplasm compare with control oocytes. And reverse transcription polymerase chain reaction (RTPCR) of parthenogenetic blstocysts revealed that acteoside increased the anti-apoptotic genes (Mcl-1, Bcl-2 and Bcl-xL), whereas reduced the expression of pro-apoptotic genes (Bax and Bak). In conclusion, based on the results, the effect of acteoside on IVM was not attractive. However, in acteoside treated group, cytoplasmic maturation seemed to be improved with morphologically uniform distribution of cytoplasmic organelles. Furthermore, embryonic development in acteoside treated group was significantly highly increased than that of non-treated group. Our results represents that addition of acteoside to the IVM medium has a beneficial effect in physiology of porcine oocytes, providing a improved method for porcine oocytes in vitro. * This work was supported by a grant (Code# PJ008148) from BioGreen21 Program, Rural Development Administration, Republic of Korea.
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