Effects of Maleic Anhydride Grafted Ethylene/Vinyl Acetate Copolymer (EVA)on the Properties of EVA/Silica Nanocomposites

Thai Hoang,Nguyen Thuy Chinh,Nguyen Thi Thu Trang,To Thi Xuan Hang,Dinh Thi Mai Thanh,Dang Viet Hung,하창식,Maëlenn Aufray 한국고분자학회 2013 Macromolecular Research Vol.21 No.11

Ternary nanocomposites based on ethylene/vinyl acetate copolymer (EVA), maleic anhydride-grafted EVA (EVAgMA), and nanosilica were prepared in a Haake Rheomixer. The structure of the EVA/EVAgMA/silica nanocomposites was characterized by Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The blending sequence was found to have a significant effect on the microstructure of EVA/EVAgMA/silica nanocomposites and the dispersion behavior of the nanosilica in the EVA matrix. The tensile properties (tensile strength and elongation at break), thermal behavior, crystalline structure and weatherability of the nanocomposites were also studied. The results showed that the above properties of the nanocomposites were enhanced remarkably using 1 wt% EVAgMA.

Preparation of Nd-Fe-B by nitrate-citrate auto-combustion followed by the reduction-diffusion process

Ma, Hao Xuan,Kim, Chang Woo,Kim, Dong Soo,Jeong, Ji Hun,Kim, In Ho,Kang, Young Soo The Royal Society of Chemistry 2015 Nanoscale Vol.7 No.17

<P>The Nd2Fe14B alloy has been successfully synthesized by nitrate-citrate auto-combustion followed by the reduction and diffusion process with low energy consumption. H3BO3, Fe(NO3)3·9H2O, and Nd(NO3)3·6H2O were used as precursors and citric acid was used as the chelating ligand of metal ions. Ammonia water was used to adjust pH to 7. CaH2 was used as a reducing agent for the reduction and diffusion process. NdFeO3 and Fe2O3 were produced during auto-combustion of gel. The combustion process of the gel was investigated by TGA/DTA curve measurements. The phase compositions were studied by XRD measurements. The differences of the overall morphology and magnetic properties were measured by SEM, TEM and vibrating sample magnetometry (VSM) at 300 K. The comparison of the magnetic properties of the reduced samples between the pellet type and the random powder type was done with VSM and it showed better magnetic properties of the pellet type Nd2Fe14B. Making a compact pellet type sample for reduction is more efficient for solid reduction and phase transition for higher coercivity.</P>

LINC01272 Suppressed Cell Multiplication and Induced Apoptosis Via Regulating MiR-7-5p/CRLS1 Axis in Lung Cancer

( Xuan Ma ),( Yang Liu ),( Hao Tian ),( Bo Zhang ),( Meiling Wang ),( Xia Gao ) 한국미생물생명공학회(구 한국산업미생물학회) 2021 Journal of microbiology and biotechnology Vol.31 No.7

LINC01272 is a long non-coding RNA (lncRNA) that has been considered as a biomarker for many diseases including lung squamous cell carcinoma. Here, we investigated the function and mechanism of LINC01272 on lung cancer (LC). The differential expression of LINC01272 in LC and normal samples was analyzed by GEPIA based on the data from TCGA-LUAD database, as survival prognosis was analyzed through Kaplan-Meier Plotter. LINC01272 overexpression plasmid and miR-7-5p mimic were transfected into A549 and PC-9 cells. LINC01272, miR-7-5p and cardiolipin synthase 1 (CRLS1) mRNA expression was measured by quantitative reverse transcription-polymerase chain reaction. Cell viability was detected through MTT assay. Cell multiplication was evaluated by cell formation assay. Cell apoptosis was assessed through flow cytometry assay. Through bioinformatics, the target miRNA of LINC01272 and downstream genes of miR-7-5p were predicted. The targeting relationship was tested by dual luciferase reporter analysis. CRLS1, B-cell lymphoma-2 (Bcl-2), BCL2-associated X (Bax) and cleaved caspase-3 protein levels were detected through western blot. LINC01272 was downregulated in LC and low LINC01272 expression had poor prognosis. In A549 and PC-9 cells, LINC01272 inhibited cell viability and multiplication and induced apoptosis. LINC01272 negatively regulated miR-7-5p and CRLS1 was a target of miR-7-5p. MiR-7-5p reversed the effect of LINC01272 on viability, multiplication, apoptosis and expression of miR-7-5p and CRLS1 as well as apoptosis-related factors (Bcl-2, Bax and cleaved caspase-3). LINC01272 suppressed cell multiplication and induced apoptosis via regulating the miR-7-5p/CRLS1 axis in LC.

공동주택 실외 커뮤니티 공간의 사례조사

마현(Ma Xuan),황연숙(Hwang, Yeon-Sook) 한국실내디자인학회 2015 한국실내디자인학회 학술대회논문집 Vol.2015 No.10

The purpose of this study is to understand of living reduced working hours and increased leisure time. Therefore, people`s ideas on life style changed and different demands on residential environment are being made. Residents of apartment want a community facility that enables constant exchange with other residents and supports living. Ideas on how to use physical space to strengthen a community is becoming an issue these days. Community facility plays a crucial role in giving a certain characteristic to the whole apartment and improving the image as a community. It also provides a physical environment and induces active participation of community life from apartment residents, The community facility in an important environment for people. This study chose four apartments in Seoul. This study focuses on the characteristics of design community facility and would like to make a proposal about space planning for people`s community facility.

공동주택 실외 놀이 공간 계획의 친환경적 평가에 관한 연구

마현 ( Xuan Ma ),어성신 ( Sungsin Eo ),김지현 ( Jihyeon Kim ),황연숙 ( Yeonsook Hwang ) 한국공간디자인학회 2017 한국공간디자인학회논문집 Vol.12 No.4

(연구배경 및 목적) 공동주택 실외 놀이 공간은 다양한 커뮤니티가 일어나고 이용 빈도가 가장 높은 공간으로 거주자의 건강과 쾌적성 향상을 가능하게 한다. 이에 따라 환경보호와 에너지 절약을 위한 친환경적 요소가 적용된 실외 놀이 공간에 대한 관심이 확대되어지면서 환경과 조화를 이루고 환경을 배려하는 친환경 실외 놀이 공간의 필요성이 높아지고 있다. 이에 본 연구는 단지 내 실외 놀이 공간의 질 향상과 개선을 위해 실외 놀이 공간에 나타난 친환경적 계획요소를 평가하여 이를 토대로 향후 공동주택 실외 놀이 공간의 친환경적 계획방안을 위한 기초자료로 활용하고자 한다. (연구방법) 본 연구의 조사대상으로는 서울시에 위치한 공동주택 실외 놀이 공간 7곳을 대상으로 조사하였으며, 현장조사를 통한 사례분석으로 진행되었다. 친환경에 관한 선행연구 및 친환경 인증 제도를 바탕으로 추출된 친환경 요소를 통해 실외 놀이 공간의 친환경 평가를 위한 체크리스트를 작성하고 조사대상에 직접 방문하여 현장조사를 실시하였다. (결과) 본 연구는 공동주택 실외 놀이 공간의 쾌적한 환경을 제공하고 이에 대한 만족도를 향상시키기 위해 놀이 공간의 친환경적 요소를 평가하였으며 친환경적 요소를 토지이용 및 교통, 생태환경, 에너지 및 환경부하 감소 부문으로 분류하였다. 첫째, 대부분의 사례에서 기존 자연지형을 활용한 놀이 공간의 조성이 계획되어 있는 것으로 나타났으나 놀이 공간으로 접근하기 위한 자전거도로와 보행자 전용도로의 사용에 있어서는 문제점이 있는 것으로 나타났다. 둘째, 인공녹화기법 적용의 경우 측면녹화나 입면녹화의 형태로 조성되어 있는 반면에 녹지축 형성에 대한 고려는 미흡한 것으로 조사되었다. 셋째, 수자원 절약을 위한 우수부하 감소에 대해서는 비교적 양호한 편으로 나타났지만 우수활용에 여부에 대한 계획은 이루어지지 않고 있었으며, 에너지 이용 및 쓰레기 처리공간에 대해서도 다소 부족한 것으로 나타났다. (결론)놀이 공간 계획시 놀이 공간의 보행자 전용도로와 자전거도로를 분리시켜 아동들의 안전성을 향상시키기 위한 노력이 필요하며, 기존의 자연형 녹지를 활용한 녹지축 조성과 더불어 다양한 생태조경을 통해 자연 친환적인 놀이 공간 계획이 이루어져야 한다. 또한 우수활용 시스템을 통한 수자원 절약과 에너지 시스템을 설치하여 자원절약 방안을 도입하고, 주변의 경치와 어우러지는 태양광 조명시설과 청결성 유지를 위한 분리수거형 쓰레기 처리공간에 대한 고려가 필요하다. 향후 이를 근거로 하여 친환경적 실외 놀이 공간의 디자인 지침으로 활용될 수 있는 구체적인 방안에 대한 후속 연구가 이루어져야 한다. (Background and Purpose) Outdoor play spaces are often the most frequently used public spaces in apartment housing, and places where various communities are formed and residents` health and comfort can be improved. This interest in outdoor play spaces, combined with growing emphasis on environment-friendly materials and energy conservation, has expanded the necessity of developing outdoor play spaces that are in harmony with and protective of the environment. The purpose of this study is to evaluate environment-friendly elements relevant to outdoor play spaces to improve the quality of outdoor play spaces within apartment complexes, and, based on the results, to provide baseline data related to environment-friendly planning measures for future apartment housing outdoor play spaces. (Method) This study targeted seven apartment housing outdoor play spaces located in Seoul and conducted a case analysis through on-site survey. Environment-friendly elements were extracted from preceding environment-friendly research and the environment-friendly certificate system, and, based on the elements, a checklist was made for environment-friendly evaluation of outdoor play spaces. Then, on-site surveys were performed at the seven target spaces using the checklist. (Results) This study, which evaluated seven play spaces and classified the environmental elements of land use, traffic, ecological environment, energy, and environmental load, found that apartment housing outdoor play spacing houses appeared to have inadequately considered the environment in their planning stages. First, although plans for play spaces utilizing the existing natural terrain were established in most cases, some had problems in the use of bike lanes and exclusive pedestrian roads near and directed toward the play space. Second, with respect to the artificial greening technique, side greening and facade greening were well applied, but the axis of the green belt was insufficiently considered. Third, although the systems for both rainwater load reduction for water resource conservation and trash and garbage disposal turned out to be relatively favorable, there was no plan for the use of rainwater, and the energy use and garbage disposal spaces were not sufficiently considered. (Conclusions) When play spaces are planned, a primary goal should be to promote children`s safety. This includes creating separate bike lanes and pedestrian roads towards play space. It also requires more attention paid to environment-friendly materials in the play space, including creating the green axis using the existing green belt as well as various types of ecology. Sustainability must also be an important consideration. Plans for outdoor play spaces should include water and energy conservation measures through rainwater use systems, water resource conservation systems, energy systems, and solar-powered lighting and recycling-type garbage disposals in harmony with adjacent landscapes to maintain cleanliness. In the future, follow-up studies should be conducted on the specific measures to utilize the study results as guidelines for the design of environment-friendly outdoor play spaces.

Kinetic Investigations of RAFT Polymerization: Difunctional RAFT Agent Mediated Polymerization of Methyl Methacrylate and Styrene

Jianying Ma,Hui Xuan Zhang 한국고분자학회 2015 Macromolecular Research Vol.23 No.1

A difunctional reversible addition-fragmentation transfer (RAFT) agent, S,S′-bis (α,α′-dimethylacetic acid)trithiocarbonate (BDAT) is synthesized and used as chain transfer agent (CTA) to mediate homopolymerization ofmethyl methacrylate (MMA) and random copolymerization of methyl methacrylate-styrene (St) system, respectively. Kinetic factors of these two polymerizations, which influence polymerization process and characteristics ofpolymers, are investigated. Experimental results show that molecular weights of polymers increase linearly withmonomer conversions and these two polymerization kinetics behaviors exhibit “controlled/living” characteristics. Forthe homopolymerization of MMA, molecular weights increase gradually and are close to their theoretical values. Wherever, for the random copolymerization of MMA-St system, the presence of St has important influence on thekinetics of copolymerization. Addition of St to this system induces an induction period and this period increase withincreasing content of St in monomer composition.

Seroprevalence and Risk Factors of Fascioliasis in Yaks, Bos grunniens, from Three Counties of Gansu Province, China

Xiao-Xuan Zhang,Sheng-Yong Feng,Jian-Gang Ma,Wen-Bin Zheng,Ming-Yang Yin,Si-Yuan Qin,Dong-Hui Zhou,Quan Zhao,Xing-Quan Zhu 대한기생충학열대의학회 2017 The Korean Journal of Parasitology Vol.55 No.1

Small gas adsorption on Co–N4 porphyrin-like CNT for sensor exploitation: a first-principles study

Zhang Xuanning,Wang Yongjie,Wang Zhenhua,Ma Shouxiao 한국탄소학회 2020 Carbon Letters Vol.30 No.2

Using frst-principles theory, we investigated the adsorption performance of CoN4-CNT towards six small gases including NO, O2, H2, H2S, NH3, and CH4, for exploiting its potential application for chemical gas sensors. The frontier molecular orbital theory was conducted to help understand the conductivity change of the proposed material at the presence of gas molecules. The desorption behavior of gas molecules from CoN4-CNT surface at ambient temperature was analyzed as well to determine its suitability for sensing application. Results show that CoN4-CNT is a promising material for O2 and NH3 sensing due to their desirable adsorption and desorption behaviors while not appropriate for sensing NO due to the poor desorption ability and for sensing CH4 and H2 given the poor adsorption behavior. Our calculation would provide a frst insight into the CoN4-embedded efect on the structural and electronic properties of single-walled CNT, and shed light on the application of CoN4-CNT towards sensing of small gases.

Lead tolerance and accumulation characteristics of three Hydrangea cultivars representing potential lead-contaminated phytoremediation plants

Wenjie Ma,Bing Zhao,Xiaofan Lv,Xuan Feng 한국원예학회 2022 Horticulture, Environment, and Biotechnology Vol.63 No.1

Heavy metal contamination of soil is a serious environmental problem worldwide. With improving ecological awareness,phytoremediation has attracted increasing attention as an economic, effi cient, and environmentally friendly method to addressheavy metal pollution. Hydrangea plants are not only colorful and aesthetically pleasing, but they also grow vigorously. Inthis study, we examined the responses of three Hydrangea cultivars to diff erent levels of lead (Pb) stress in terms of theirgrowth responses, biochemical changes, and heavy metal accumulation. We found that (1) no visual heavy metal toxicitysymptoms were observed in the three Hydrangea cultivars under any Pb treatment. (2) At low concentrations of Pb (100–200 mg kg −1 ), the root length of the three cultivars increased signifi cantly compared with that of the control; no signifi cantchange was found in shoot biomass in the three cultivars under any Pb treatment. (3) The biochemical changes in responseto Pb stress diff ered between the cultivars. (4) Under all Pb treatments, the Pb concentrations in the roots were signifi cantlyhigher than those in the shoots of the cultivars, with translocation factor (TF) values < 1. Our results suggest that all threeHydrangea cultivars tested have the potential to tolerate high Pb levels in soil and showed Pb phytostabilization tendencieswith features essential for phytoextraction.

Dynamic analysis of high-speed railway train-bridge system after barge collision

Xia, Chaoyi,Ma, Qin,Song, Fudong,Wu, Xuan,Xia, He Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.67 No.1

In this paper, a framework is proposed for dynamic analysis of train-bridge systems with a damaged pier after barge collision. In simulating the barge-pier collision, the concrete pier is considered to be nonlinear-inelastic, and the barge-bow is modeled as elastic-plastic. The changes of dynamic properties and deformation of the damaged pier, and the additional unevenness of the track induced by the change of deck profile, are analyzed. The dynamic analysis model for train-bridge coupling system with a damaged pier is established. Based on the framework, an illustrative case study is carried out with a $5{\times}32m$ simply-supported PC box-girder bridge and the ICE3 high-speed train, to investigate the dynamic response of the bridge with a damaged pier after barge collision and its influence on the running safety of high-speed train. The results show that after collision by the barge, the vibration properties of the pier and the deck profile of bridge are changed, forming an additional unevenness of the track, by which the dynamic responses of the bridge and the car-body accelerations of the train are increased, and the running safety of high-speed train is affected.