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Viet-Cuong Han,유난희(Nan Hee Yu),윤혁준(Hyeokjun Yoon),안능호(Neung-Ho Ahn),Youn Kyoung Son,Byoung-Hee Lee,김진철(Jin-Cheol Kim) 한국식물병리학회 2022 Plant Pathology Journal Vol.38 No.2
Though information exists regarding the pathogenesis of the shot-hole disease (SH) in flowering cherry (FC), there has been a lack of research focusing on SH management. Therefore, here, we investigated the inhibitory activities of antagonistic bacteria against SH pathogens both in vitro and in vivo as well as their biochemical characteristics and bioactive compounds. Two biosurfactant- producing bacterial antagonists, identified as Bacillus velezensis strains JCK-1618 and JCK-1696, exhibited the best effects against the growth of both bacterial and fungal SH pathogens in vitro through their cell-free culture filtrates (CFCFs). These two strains also strongly inhibited the growth of the pathogens via the action of their antimicrobial diffusible compounds and antimicrobial volatile organic compounds (VOCs). Crude enzymes, solvent extracts, and biosurfactants of the two strains exhibited antimicrobial activities. Liquid chromatography/electrospray ionization timeof- flight mass spectrometric analysis of the partially purified active fractions revealed that the two antagonists produced three cyclic lipopeptides, including iturin A, fengycin A, and surfactin, and a polyketide, oxydifficidin. In a detached leaf assay, pre-treatment and co-treatment of FC leaves with the CFCFs led to a large reduction in the severity of the leaf spots caused by Epicoccum tobaicum and Bukholderia contaminans, respectively. In addition, the two antagonists produced indole-3-acetic acid, siderophore, and a series of hydrolytic enzymes, along with the formation of a substantial biofilm. To our knowledge, this is the first report of the antimicrobial activities of the diffusible compounds and VOCs of B. velezensis against the SH pathogens and their efficiency in the biocontrol of SH.
Han, Min,Ryu, Beo Deul,Ko, Kang Bok,Jo, Chang Hee,Lim, Chang-hyun,Cuong, Tran Viet,Han, Nam,Hong, Chang-Hee Elsevier 2019 Journal of crystal growth Vol.507 No.-
<P><B>Abstract</B></P> <P>Hexagonal boron nitride (hBN) combined with III-nitride materials is attracting increasing attention for widening the applications of III-nitride materials. Three methods were used to grow the hBN buffer layer: (i) 2-step (low and high temperature), (ii) 1-step (high temperature), and (iii) pre-TEB surface treatment method. The optical properties of the hBN buffer layers were determined through Raman spectroscopy and absorbance measurements to characterize the combination between the III-nitride material (AlN) and hBN. The crystal quality of the AlN film grown under the same conditions on three hBN buffer layers has investigated by X-ray diffraction (XRD). XRD data established that the surface roughness of the hBN layer and density of the AlN nuclei are important factors for crystal quality of III-nitride material. The surface roughness of the hBN layers varied for the different growth methods, while the V/III ratio for each method remained unchanged. This difference in the surface roughness was confirmed to be related to the bonding configuration within the hBN layer, and was further confirmed by X-ray photoelectron spectroscopy to be due to the strong interactions between BN with the substrate (B<SUB>1</SUB>). In addition, the strongly interacting BN bond, which is dependent on the method used for the growth of the buffer layer, resulted in a peel-off of the AlN layer. This phenomenon did not occur at the hBN/sapphire interface, but occurred at the AlN/hBN interface, confirming that the strong interaction bonding between BN and the substrate weakens adhesion at the AlN/hBN interface.</P> <P><B>Highlights</B></P> <P> <UL> <LI> AlN films grown on various hexagonal boron nitride buffer layer by MOCVD. </LI> <LI> The XPS results of BN impacts adhesion to the AlN template. </LI> <LI> Surface roughness of hexagonal boron nitride buffer significantly impacts the density of AlN nuclei. </LI> </UL> </P>
Reduced thermal resistance of heat sink using graphene oxide decorated with copper nanoparticles
Ryu, Beo Deul,Han, Min,Ko, Kang Bok,Lee, Kyu-Han,Cuong, Tran Viet,Han, Nam,Kim, Kyurin,Ryu, Jae Hyung,Park, Noh-Joon,Lim, Yongsu,Thanh, Do Trong,Jo, Chang Hee,Ju, Kwanseon,Hong, Chang-Hee Elsevier 2019 Materials research bulletin Vol.110 No.-
<P><B>Abstract</B></P> <P>Three–dimensional thermal interface materials made of graphene oxide (GO) and copper nanoparticles (Cu NPs) were applied for enhancing light–emitting diode heat dissipation. The effect of the stacking order of GO and Cu NPs on thermal resistance was explored by creating two types of samples: spray–coated with a mixed GO–Cu NPs and layer–by–layer stacked with GO/Cu NPs/GO. A reduction of thermal resistance for mixed GO–Cu NPs and layer–by–layer stacked structure by 37% and 33%, respectively, compared to that of Al heat sink. The lower thermal resistance of the mixed GO–Cu NPs sample is attributed to the fact that distributed Cu NPs at the step edge of GO sheets enhances the out–of–plane heat transfer at wrinkles/folds of GO interlayers. Therefore, a mixed GO–Cu NPs is considered as a promising composite for effective thermal management of high–performance optoelectronic devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Three–dimensional thermal interface materials made of graphene oxide and copper nanoparticles (GO–Cu NPs) have synthesized. </LI> <LI> The effect of the stacking order of GO–Cu NPs on thermal resistance has explored for enhancing LED heat dissipation. </LI> <LI> Analysis by a FLIR camera has showed that the combination of GO and Cu NPs enabled heat dissipation properties. </LI> <LI> The thermal resistance of the mixed GO–Cu NPs structure is less 37 % than that of the Al heat sink. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Ryu, Beo Deul,Han, Min,Han, Nam,Park, Young Jae,Ko, Kang Bok,Lim, Tae Hyun,Chandramohan, S.,Cuong, Tran Viet,Choi, Chel-Jong,Cho, Jaehee,Hong, Chang-Hee American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.24
<P>A reduced graphene oxide (GO) layer was produced on undoped and n-type GaN, and its effect on the current- and heat-spreading properties of GaN-based light-emitting diodes (LEDs) was studied. The reduced GO inserted between metal electrode and GaN semiconductor acted as a conducting layer and enhanced lateral current flow in the device. Especially, introduction of the reduced GO layer on the n-type GaN improved the electrical performance of the device, relative to that of conventional LEDs, due to a decrease in the series resistance of the device. The enhanced current-spreading was further of benefit, giving the device a higher light output power and a lower junction temperature at high injection currents. These results therefore indicate that reduced GO can be a suitable current and heat-spreading layer for GaN-based LEDs.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-24/am506308t/production/images/medium/am-2014-06308t_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am506308t'>ACS Electronic Supporting Info</A></P>
Thi-Hoan Luong,Dang-Minh-Chanh Nguyen,Thi-Nga Trinh,Viet-Cuong Han,Woo-Jin Jung 한국응용생명화학회 2022 Journal of Applied Biological Chemistry (J. Appl. Vol.65 No.4
In recent years, research into medicinal herbs with antioxidative activities has increased. Chrysanthemum morifolium and Chrysanthemum indicum are aromatic herb plants and that have long been used in traditional Vietnamese medicine. This study aims to evaluate the chemical compositions and antioxidative activities of essential oils hydrodistilled from the flower heads of C. morifolium and C. indicum. The chemical compositions of the essential oils were compared using gas chromatography/mass spectrometry (GC/MS) analysis. The antioxidative activity was determined and evaluated spectroscopically by the 2,2-diphenyl- 1-picrylhydrazyl (DPPH) radical scavenging, metal chelating activity, reducing power, and total antioxidant capacity assays. According to the GC/MS results, chrysanthenone was predominant in the essential oils of both C. morifolium (64.14%) and C. indicum (32.02%). This is the first report of the identification of chrysanthenone as a major constituent of the essential oil of C. morifolium. Both Chrysanthemum oils were also revealed to possess antioxidant potential, exhibiting high antioxidative activities. In particular, the DPPH radical scavenging activities of the C. morifolium and C. indicum oils at a concentration of 100 mg/mL were 76.9 and 83.2%, respectively. The metal chelating values of C. morifolium and C. indicum were 0.85 and 0.76, whereas the reducing power values of that at 100 mg/mL were 0.76 and 0.71, respectively. This study provides the chemical properties of the essential oils of both C. morifolium and C. indicum grown in Vietnam and their potential antioxidant capacity