One-step production of highly anisotropic particles via a microfluidic method

Xia, Ming,Go, Eun Min,Choi, Kyu Hwan,Lim, Jin Hyun,Park, Bumkyo,Yu, Taekyung,Im, Sang Hyuk,Kwak, Sang Kyu,Park, Bum Jun Elsevier 2018 Journal of industrial and engineering chemistry Vol.64 No.-

<P><B>Abstract</B></P> <P>We introduce a promising protocol that can be used to fabricate polymer particles with a high degree of shape anisotropy; this method can be utilized with a variety of microfluidic generation methods. Low-density microparticles and high-density nanoparticles vertically migrated in a polymer solution confined in emulsion droplets that were produced via a microfluidic method. As the solvent evaporated in individual droplets at ambient conditions, the low-density microparticles migrated upward because their density was lower than that of the polymer solution. The high-density nanoparticles that were initially well-dispersed in the droplet phase became destabilized upon solvent removal, leading to the formation of aggregates and sedimentation in a downward direction. The migration of the particle components during solvent evaporation induced shape deformation/modification of the emulsion droplets; consequently, polymer particles with highly anisotropic shapes were created after drying.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Multiple roles of palladium-coated magnetic anisotropic particles as catalysts, catalyst supports, and micro-stirrers

Xia, Ming,Kim, Kyung Hak,Lee, Jongwon,Go, Eun Min,Park, Bumkyo,Yu, Taekyung,Kwak, Sang Kyu,Na, Hyon Bin,Park, Bum Jun Elsevier 2018 Chemical Engineering Journal Vol.339 No.-

<P><B>Abstract</B></P> <P>We report the external field-guided shape transformation of magnetite-polymer composite particles that play multiple roles in heterogeneous chemical reactions, such as catalysts, catalyst supports, and micro-stirrers. A microfluidic method was used to generate monodispersed emulsion droplets composed of polystyrene, magnetite nanoparticles (MNPs), and chloroform. While the solvent in the droplets was dried in the presence of an external magnetic field, the emulsion droplets were deformed or elongated along the field direction, consequently leading to magnetically responsive particles with anisotropic shape after complete removal of the solvent. Coarse-grained molecular dynamic simulations demonstrated that the shape deformation was due to destabilization of the MNPs upon solvent drying and migration of the aggregated MNPs in the polymer matrix along the external field. The particle shape could be readily tunable by modulating the field strength and direction as well as the concentrations of the MNPs and polymer. We further revealed that these magnetic anisotropic particles coated with palladium nanoparticles could be used as catalysts, catalyst supports, micro-stirrers when the particles were dispersed in a small confined volume of a catalytic precursor solution.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Anisotropic magnetic particles are fabricated via the microfluidic method. </LI> <LI> External fields can control the shape anisotropy of the particles. </LI> <LI> Pd-coated particles are used as catalysts, catalyst supports, and micro-stirrers. </LI> </UL> </P>

Function of Global Regulator CodY in Bacillus thuringiensis BMB171 by Comparative Proteomic Analysis

( Ming Xia Qi ),( Fei Mei ),( Hui Wang ),( Ming Sun ),( Ge Jiao Wang ),( Ziniu Yu ),( Yeon Ho Je ),( Ming Shun Li ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.2

CodY is a highly conserved protein in low G+C gram-positive bacteria that regulates genes involved in sporulation and stationary-phase adaptation. Bacillus thuringiensis is a grampositive bacterium that forms spores and parasporal crystals during the stationary phase. To our knowledge, the regulatory mechanism of CodY in B. thuringiensis is unknown. To study the function of CodY protein in B. thuringiensis, BMB171codY- was constructed in a BMB171 strain. A shuttle vector containing the ORF of cry1Ac10 was transformed into BMB171 and BMB171codY-, named BMB171cry1Ac and BMB171codY-cry1Ac, respectively. Some morphological and physiological changes of codY mutant BMB171codY-cry1Ac were observed. A comparative proteomic analysis was conducted for both BMB171codY-cry1Ac and BMB171cry1Ac through two-dimensional gel electrophoresis and MALDI-TOF-MS/MS analysis. The results showed that the proteins regulated by CodY are involved in microbial metabolism, including branched-chain amino acid metabolism, carbohydrate metabolism, fatty acid metabolism, and energy metabolism. Furthermore, we found CodY to be involved in sporulation, biosynthesis of poly-β-hydroxybutyrate, growth, genetic competence, and translation. According to the analysis of differentially expressed proteins, and physiological characterization of the codY mutant, we performed bacterial one-hybrid and electrophoretic mobility shift assay experiments and confirmed the direct regulation of genes by CodY, specifically those involved in metabolism of branched-chain amino acids, ribosomal recycling factor FRR, and the late competence protein ComER. Our data establish the foundation for in-depth study of the regulation of CodY in B. thuringiensis, and also offer a potential biocatalyst for functions of CodY in other bacteria.

One-step production of highly anisotropic particles via a microfluidic method

Ming Xia,고은민,최규환,임진현,박범교,유태경,임상혁,곽상규,박범준 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.64 No.-

We introduce a promising protocol that can be used to fabricate polymer particles with a high degree of shape anisotropy; this method can be utilized with a variety of microfluidic generation methods. Low-density microparticles and high-density nanoparticles vertically migrated in a polymer solution confined in emulsion droplets that were produced via a microfluidic method. As the solvent evaporated in individual droplets at ambient conditions, the low-density microparticles migrated upward because their density was lower than that of the polymer solution. The high-density nanoparticles that were initially well-dispersed in the droplet phase became destabilized upon solvent removal, leading to the formation of aggregates and sedimentation in a downward direction. The migration of the particle components during solvent evaporation induced shape deformation/modification of the emulsion droplets; consequently, polymer particles with highly anisotropic shapes were created after drying.

Analysis of Active Components and Proteomics of Chinese Wild Rice (Zizania latifolia (Griseb) Turcz) and Indica Rice (Nagina22)

Ming-xia Jiang,Li-jie Zhai,Hua Yang,Shu-menghui Zhai,Cheng-kai Zhai 한국식품영양과학회 2016 Journal of medicinal food Vol.19 No.8

The ancient Chinese wild rice (Zizania latifolia (Griseb) Turcz) (CWR) has valuable biological and medicinal functions. To assess the advantages lost in modern cultivated rice after domestication, we compared the composition of bioactive compounds and the results of proteomic analysis with those of Indica rice (N22). We used routine methods to determine the protein, total dietary fiber, amino acid, mineral substance, plant secondary metabolites, and amino acid composition of CWR and N22. The protein and mineral contents of CWR were two times that of N22, and the levels of calcium, potassium, magnesium, chromium, iron, and zinc were significantly higher than those of N22 (P < .05). There was ~7.6 times more dietary fiber in CWR than in N22, but fewer carbohydrates (P < .05). Anthocyanins and chlorophyll were detected in CWR, but were absent from N22. Compared with N22, CWR had 53, 19, and 5.4 times higher (P < .05) levels of saponins, flavonoids, and plant sterols, respectively. The amino acid score of CWR was 66.6, which was significantly higher than N22. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) indicated that the main seed proteins of CWR were glutelins, including both acid and alkaline subunits, which were approximately twice those of N22. To investigate the differences in protein profiles between CWR and N22, we conducted two-dimensional electrophoresis (2-DE) analysis of the total proteins in the seeds of the two rice species. 2-DE gels revealed 19 differentially expressed proteins. Information obtained from peptide mass fingerprinting indicates that glutelin precursor caffeoyl coenzyme A (CoA) O-methyltransferase and putative bithoraxoid-like protein can provide good gene sources for improving rice quality.

On Obstacles to Security Cooperation in Northeast Asia

( Xia Ming Yang ) 충남대학교 북미주연구소 2011 북미주학연구 Vol.20 No.-

In Northeast Asia further cooperation for peace and security is hampered by mutual distrust derived from cold war legacy, rising nationalism, territory disputes and gaps in historical perception, and also by North Korea`s tactics for survival, Policy-makers, scholars and commentators, however, should, at least, not incite nationalism for their own political gains and do their best to facilitate the tendency of economical interdependence in the region. When talking about a security mechanism in Northeast Asia, many scholars mentioned Europe as an example. Indeed, Europe with common currency, foreign and defense policy and free movement of their people across each other`s borders is admirable. However, one should bear in mind chat both nation states and modern nationalism originated in Europe in 17th and 19th century separately and it was only after numerous wars, including two World Wars, and tremendous sufferings that nation states in Europe gradually gave up many of their once considered absolute privileges for the good of their people and nationalism and territory disputes are no longer an issue any more. It will take Northeast Asia some time and certain cost before they reach tint stage.

How Does Peer Feedback Training Work in EFL Writing?

( Ming Xia Gao ) 한국외국어대학교 외국어교육연구소 2014 외국어교육연구 Vol.28 No.2

Peer feedback, in which students work together in pairs or small groups to critique and provide comments on one another’s writing, is compatible with communicative approaches to second language acquisition (SLA) and process approaches to foreign language writing. This study, drawing on Vygotsky’s sociocultural learning theory, conducted a pretest -posttest comparison group quasi experimental design with multiple data being collected and analyzed quantitatively by using SPSSWID (ver. 17.0), to explore what role trained peer feedback plays in EFL writing context. Results of a series of t-tests in quantitative analysis showed that peer feedback training had positive effects on participants in various aspects. The experimental group students gained more than control group students in their posttest writing task. They outperformed the control group students in terms of comment quantity and quality, especially generating more specific and relevant comments on global issues and implementing more peer comments into their revisions. Peer feedback training also helped students cultivate more positive attitudes towards EFL writing. These findings suggest that peer feedback training has shown strong positive effects on EFL learners, that is, EFL students can perform peer feedback both efficiently and effectively as long as they are well-trained.

Diversity of Microorganisms in Decaying Maize Stalks Revealed by a Molecular Method

Ming-Xia Yang,Han-Bo Zhang 한국미생물학회 2007 The journal of microbiology Vol.45 No.4

Microbial diversity in decaying maize stalk was characterized by constructing and analyzing rRNA gene clone library. Total 47 OTUs were obtained from 82 bacterial clones, including Proteobacteria (64.6%), Actinobacteria (30.5%), Bacteroidetes (2.4%) and Firmicutes (2.4%). Most proteobacterial clones were members of Rhizobium, Pseudomonas and Stenotrophomonas. Eighty-four percent of Actinobacteria was related to Microbacterium. Only 14 OTUs were identified from 124 fungal clones, including Ascomycota (88%) and Basidiomycota (12%). Sixty percent of Ascomycota were members of Eupenicillium and Paecilomyces but all Basidiomycota were close to Kurtzmanomyces nectairei.

Fabrication of palladium and alginate composite hydrogel particles as a recyclable catalyst

( Xia Ming ),박범준 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0

We presented a facial and robust strategies to fabricate a recyclable and environmentally friendly catalyst particles for the 4-nitrophenol reduction by using the dripping method. An alginate aqueous solution containing palladium nanoparticles (Pd) and magnetite nanoparticles (MNPs) was dropped via a tapered glass capillary, and the generated droplets were collected using an aqueous solution with divalent cations. The alginate hydrogel was formed immediatedly after the droplets contacted with the aqueous solution. The prepared PdNPs/MNPs-embedded alginate particles were used as a catalyst, catalyst support, and magnetic stirrer for the reduction of 4-nitrophenol. The catalytic reaction rate were found to depend on the magnetic stirring of the alginate hydrogels. In addition, we further investigated the recyclability and stability by varying the alginate concentration, divalent cation species, and incubation protocols.

Can alginate hydrogels be used as catalyst supports?

( Xia Ming ),박범준 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.1