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Khan, Nazmul Abedin,Jhung, Sung-Hwa Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.12
Cu-BTC[$Cu_3(BTC)_2(H_2O)_3$, BTC = 1,3,5-benzenetricarboxylate], one of the most well-known metal-organic framework materials (MOF), has been synthesized under atmospheric pressure and room temperature by using ultrasound. The Cu-BTC can be obtained in 1 min in the presence of DMF (N,N-dimethylformamide), suggesting the possibility of continuous production of Cu-BTC. Moreover, the surface area and pore volume show that the concentration of DMF is important for the synthesis of Cu-BTC having high porosity. The morphology and phase also depend on the concentration of DMF : Cu-BTC cannot be obtained at room temperature in the absence of DMF and aggregated Cu-BTC (with low surface area) is produced in the presence of high concentration of DMF. It seems that the deprotonation of benzenetricarboxylic acid by base (such as DMF) is inevitable for the room temperature syntheses.
Lee, Sungkyun,Park, Won Kyu,Yoon, Yeojoon,Baek, Byeongmin,Yoo, Jin Sun,Kwon, Seok Bin,Kim, Do Hun,Hong, Young Joon,Kang, Bong Kyun,Yoon, Dae Ho,Yang, Woo Seok Elsevier Sequoia 2019 Materials Science and Engineering B Vol. No.
<P><B>Abstract</B></P> <P>The conventional thermal chemical vapor deposition (T-CVD) equipment takes a long time to synthesize a thin film, which is the stumbling block in the commercialization of monolayer graphene. Rapid thermal chemical vapor deposition (RT-CVD) equipment is suitable for rapid graphene synthesis on most surfaces of large area transition metals. The initial graphene domains synthesized by RT-CVD were visualized and compared with graphene synthesized by T-CVD. The number of graphene domains grown by RT-CVD was approximately 12.31% larger than those synthesized by T-CVD. The surface of the thermally treated metal substrate determines the density and shape of the graphene domains due to the reduced surface irregularities and hence flattens. As a result of the thermal treatment of the copper foil, the I<SUB>D</SUB>/I<SUB>G</SUB> value of RT-CVD graphene decreased by 12.5%. Thus, it was confirmed that the electrical characteristics were improved as the average value of the sheet resistance reduced by 15.8%.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Graphene films were fast-synthesized by rapid thermal chemical vapor deposition for mass production. </LI> <LI> The density and shape of initial graphene domains was determined by the surface roughness of the metal substrate. </LI> <LI> The surface roughness of copper foil was improved by thermal treatment. </LI> <LI> The high quality graphene by Rapid thermal chemical vapor deposition was optimized on the thermal treated cu foil for 85 min. </LI> </UL> </P>
Jennifer Hunter,Susan Arentz,Joshua Goldenberg,Guo-yan Yang,Jennifer Beardsley,이명수,Stephen P. Myers 한국한의학연구원 2020 Integrative Medicine Research Vol.9 No.3
Background: The COVID-19 pandemic has led to an explosion of rapid reviews geared towards providing time sensitive answers for clinical and policy decision-makers. Rapid reviews (RRs) strike a balance between rigour and rapidity to minimise bias and optimise transparency within specified constraints. Methods: This review article appraised the methods and reporting standards of a convenience sample of RR protocols and RRs of COVID-19 clinical management questions, published in the first six-months of 2020. Inclusion criteria were all RR protocols evaluating traditional, complementary, and integrative medicine (TCIM) registered on PROSPERO, and all RRs indexed on PubMed or published on the Oxford COVID-19 Evidence Service. A purpose-specific 9-item reporting checklist reflecting recommended minimum requirements for RRs was applied. Findings were synthesised and narrated in the context of methodological considerations for conducting and reporting RRs of TCIM. Results: Included studies were five RR protocols of TCIM and 16 RRs, of which five considered TCIM. Wide variations in RR methods were proposed or applied, as were the reporting standards. All five RRs that evaluated TCIM had the lowest reporting standards that limited reproducibility and transparency. Despite accepted recommendations, most RRs did not publish a protocol. Conclusions: We propose that specific research disciplines, such as TCIM, have a uniqueness that may lead to unacceptable outputs if minimum methodological standards are not applied. The recommended minimum requirements will optimise the credibility of rapid reviews of TCIM and limit the risk of prematurely disregarding a potentially effective intervention.
Rapid synthesis of mullite powders
Remzi Gören,Cem Özgür 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.3
This study covers the synthesis of high purity mullite powders using ultrasonic spray pyrolysis and the microstructural evaluation of bulk materials prepared by using this powder. Tetraethylorthosilicate and aluminum nitrate nanohydrate chemicals were used to prepare an aqueous solution and this solution was turned into aerosol droplets using an ultrasonic nebulizer with a resonance frequency of 1.63MHz. These aerosol droplets were carried to the vertical tube furnace the temperature of which was set beforehand by using a gas with a flow rate of 1.5 L minute-1. Spherically shaped mullite powders were successfully synthesized at 1075 oC according to the results of XRD and FTIR. Bulk materials were obtained by sintering the pressed mullite powders at different temperatures (1500, 1550, 1600 and 1650 oC) with a soaking time of 5 hours. SEM images show that the particle shape changes wth the sintering temperature of the bulk ceramic. For low temperature sintering,the particles are still quite spherical whereas they tend to form a rod-like structure with an increase in the sintering temperature.
Facile Syntheses of Metal-organic Framework Cu3(BTC)2(H2O)3 under Ultrasound
Nazmul Abedin Khan,정성화 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.12
Cu-BTC[Cu3(BTC)2(H2O)3, BTC = 1,3,5-benzenetricarboxylate], one of the most well-known metal-organic framework materials (MOF), has been synthesized under atmospheric pressure and room temperature by using ultrasound. The Cu-BTC can be obtained in 1 min in the presence of DMF (N,N-dimethylformamide), suggesting the possibility of continuous production of Cu-BTC. Moreover, the surface area and pore volume show that the concentration of DMF is important for the synthesis of Cu-BTC having high porosity. The morphology and phase also depend on the concentration of DMF : Cu-BTC cannot be obtained at room temperature in the absence of DMF and aggregated Cu-BTC (with low surface area) is produced in the presence of high concentration of DMF. It seems that the deprotonation of benzenetricarboxylic acid by base (such as DMF) is inevitable for the room temperature syntheses.
Ceramurgica ; Elsevier Science Ltd 2016 Ceramics international Vol.42 No.13
Al-TiC nanopowders from the mixture of Ti and Al<SUB>4</SUB>C<SUB>3</SUB> were made by high energy ball milling. Highly dense nanostructured 4Al-3TiC composite was simultaneously synthesized and consolidated by high-frequency induction heating within one minute from the mechanically activated powders. The microstructure and mechanical properties (hardness and fracture toughness) were investigated using FE-SEM, XRD and Vickers hardness tester.
High-frequency induction heated synthesis and consolidation of nanocrystalline B-SiC composite
손인진 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.10
Metal matrix composites combine metallic properties (ductility and toughness) with ceramic characteristics (high strength andmodulus), leading to greater strength in shear and compression and to higher service temperature capabilities. The attractivephysical and mechanical properties can be obtained with metal matrix composites, such as high wear resistance, strength-toweigh ratio, fatigue strength, temperature stability and specific modulus. Nanopowders of Si and B4C were fabricated by highenergy ball milling. Highly dense nanostructured 4B-SiC composite was simultaneously synthesized and consolidated by highfrequencyinduction heating within three minutes from the mechanically activated powders. The microstructure, phases andmechanical properties (hardness and fracture toughness) were investigated using FE-SEM, XRD and Vickers hardness tester. The relative density of the composite was 98%, and the average grain sizes of B and SiC in composite are 60 and 75 nm,respectively. The fracture toughness of SiC can be improved by the addition of B to form a composite.
Na-Ra Park,Seong-Hyeon Jeon,Je-Shin Park,김원백,손인진 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.6
A nanocrystalline 4Fe-Al2O3 composite was simultaneously synthesized and consolidated by a high frequency induction heated sintering method within 2 minutes from mechanically activated powders of Fe2O3 and 2FeAl. The average grain sizes of Fe and Al2O3 were 72 and 43 nm, respectively. The mechanical properties of the composite were investigated.