SiC is a material with excellent strength, heat resistance, and corrosion resistance. It is generally used as a material for SiC invertors, semiconductor susceptors, edge rings, MOCVD susceptors, and mechanical bearings. Recently, SiC single crystals for LED are expected to be a new market application. In addition, SiC is also used as a heating element applied directly to electrical energy. Research in this study has focused on the manufacture of heating elements that can raise the temperature in a short time by irradiating SiC-I2 with microwaves with polarization difference, instead of applying electric energy directly to increase the convenience and efficiency. In this experiment, Polydimethylsilane (PDMS) with 1,2 wt% of iodine is synthesized under high temperature and pressure using an autoclave. The synthesized Polycarbosilane (PCS) is heat treated in an argon gas atmosphere after curing process. The experimental results obtain resonance peaks using FT-IR and UV-Visible, and the crystal structure is measured by XRD. Also, the heat-generating characteristics are determined in the frequency band of 2.45 GHz after heat treatment in an air atmosphere furnace.

Our objective of this study is to design and develop a polyethylene glycol ( PEG2000)-modified multiwall carbon nanotube (PEGylated MWCNT) formulation for oral controlled metronomic chemotherapeutic drug delivery. Multiwall carbon nanotubes undergo various chemical modifications including oxidation with strong acids, conjugation of polyethylene glycol, and coating with cellulose acetate phthalate which resulted in the formation of aqueous dispersion and prevention of drug degradation in acidic environment. Advanced analytical procedure such as Fourier transform infra-red, X-ray diffraction, differential scanning calorimetry, thermal gravimetric analysis, transmission electron microscopy, and dynamic light scattering techniques were used to evaluate physicochemical characterization. We also performed in vitro cytotoxic study by MTT assay and results revealed that carboplatin-loaded PEGylated MWCNTs did not show significant detrimental effect on the viability of MDA-MB-231 (human breast cancer) cells. The maximum encapsulation and drug-loading capacity were determined to be 71.58 ± 0.04 and 39.62 ± 0.07%, respectively. The release of carboplatin from PEGylated MWCNTs was investigated at simulated intestinal fluid (SIF), pH 6.8, after optimizing at simulated gastric fluid (SGF), pH 1.2, by enteric coating. Enteric-coated PEGylated MWCNTs exhibit pH-responsive drug activity in a sustained manner especially at pH 6.8. This surface modification strongly suggests that PEGylated MWCNTs could be a potential carrier for metronomic chemotherapeutic agent for high drug resistance, drug with maximum adverse effect and poorly oral bioavailable drugs.

For solving phase separation of nanoparticles and graphene oxide (GO) in the application process, MgWO4– GO nanocomposites were successfully synthesized using three different dispersants via a facile solvothermal-assisted in situ synthesis method. The structure and morphology of the prepared samples were characterized by X-ray diffraction, Scanning electron microscopy, Transmission electron microscopy, Fourier transform infrared and Raman techniques. The experimental results show that MgWO4 nanoparticles are tightly anchored on the surfaces of GO sheets and the agglomeration of MgWO4 nanoparticles is significantly weakened. Additionally, MgWO4– GO nanocomposites are more stable than self-assembly MgWO4/ GO, which there is no separation of MgWO4 nanoparticles and GO sheets by ultrasound after 10 min. The catalytic results show that, compared with bare MgWO4, MgWO4– GO nanocomposites present better catalytic activities on the thermal decomposition of cyclotetramethylenete tranitramine (HMX), cyclotrimethylene trinitramine (RDX) and ammonium perchlorate (AP). The enhanced catalytic activity is mainly attributed to the synergistic effect of MgWO4 nanoparticles and GO. MgWO4– GO prepared using urea as the dispersant has the smallest diameter and possesses the best catalytic action among the three MgWO4– GO nanocomposites, which make the decomposition temperature of HMX, RDX and AP reduce by 10.71, 11.09 and 66.6 °C, respectively, and the apparent activation energy of RDX decrease by 68.6 kJ mol−1.

SrMoO4:RE3+ (RE=Dy, Sm, Tb, Eu, Dy/Sm) phosphors are prepared by co-precipitation method. The effects of the type and the molar ratio of activator ions on the structural, morphological, and optical properties of the phosphor particles are investigated. X-ray diffraction data reveal that all the phosphors have a tetragonal system with a main (112) diffraction peak. The emission spectra of the SrMoO4 phosphors doped with several activator ions indicate different multicolor emissions: strong yellow-emitting light at 573 nm for Dy3+, red light at 643 nm for Sm3+, green light at 545 nm for Tb3+, and reddish orange light at 614 nm for Eu3+ activator ions. The Dy3+ singly-doped SrMoO4 phosphor shows two dominant emission peaks at 479 and 573 nm corresponding to the 4F9/2→6H15/2 magnetic dipole transition and 4F9/2→6H13/2 electric dipole transition, respectively. For Dy3+ and Sm3+ doubly-doped SrMoO4 phosphors, two kinds of emission peaks are observed. The two emission peaks at 479 and 573 nm are attributed to 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions of Dy3+ and two emission bands centered at 599 and 643 nm are ascribed to 4G5/2→6H7/2 and 4G5/2→6H9/2 transitions of Sm3+. As the concentration of Sm3+ increases from 1 to 5 mol%, the intensities of the emission bands of Dy3+ gradually decrease; those of Sm3+ slowly increase and reach maxima at 5 mol% of Sm3+ ions, and then rapidly decrease with increasing molar ratio of Sm3+ ions due to the concentration quenching effect. Fluorescent security inks based on as-prepared phosphors are synthesized and designed to demonstrate an anticounterfeiting application.

W2C is synthesized through a reaction-sintering process from an ultrafine-W and WC powder mixture using spark plasma sintering (SPS). The effect of various parameters, such as W:WC molar ratio, sintering temperature, and sintering time, on the synthesis behavior of W2C is investigated through X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) analysis of the microstructure, and final sintered density. Further, the etching properties of a W2C specimen are analyzed. A W2C sintered specimen with a particle size of 2.0 μm and a relative density over 98% could be obtained from a W-WC powder mixture with 55 mol%, after SPS at 1700℃ for 20 min under a pressure of 50 MPa. The sample etching rate is similar to that of SiC. Based on X-ray photoelectron spectroscopy (XPS) analysis, it is confirmed that fluorocarbon-based layers such as C-F and C-F2 with lower etch rates are also formed.

CeO2 nanoparticles, employed in a lot of fields due to their excellent oxidation and reduction properties, are synthesized through a solvothermal process, and a high specific surface area is shown by controlling, among various process parameters in the solvothermal process, the type of solvent. The synthesized CeO2 nanoparticles are about 11~13 nm in the crystallite size and their specific surface area is about 65.38~84.65 m2/g, depending on the amount of ethanol contained in the solvent for the solvothermal process; all synthesized CeO2 nanoparticles shows a fluorite structure. The dispersibility and microstructure of the synthesized CeO2 nanoparticles are investigated according to the species of dispersant and the pH value of the solution; an improvement in dispersibility is shown with the addition of dispersants and control of the pH. Various dispersing properties appear according to the dispersant species and pH in the solution with the synthesized CeO2 nanoparticles, indicating that improved dispersing properties in the synthesized CeO2 nanoparticles can be secured by applying dispersant and pH control simultaneously.

In this study, hair waste was converted into active carbon for the first time and its characteristics were analyzed. As chemical activation tool, zinc chloride ( ZnCl2) was impregnated and then carbonized under different temperatures (250–300 °C). Scanning Electron Microscope (SEM) images showed an increase in the pore density, radius and volume of pores. X-ray diffraction analysis (XRD) showed that the samples had an amorphous structure. In Fourier-transform infrared (FT-IR) spectroscope analysis, C=C and N–H vibrations observed in 1515–1520 cm−1 wave number of protein molecules were found to disappear with the increase in temperature. With Raman spectroscopy, the behaviors of D peak at 1344 cm−1 wave number and G peak at 1566 cm−1 wave number expressing structure layout in carbonized structures were analyzed depending on the temperatures. Between these intensities, (ID/IG) the rate was found to differ in direct proportion to temperature. XRD spectrums showed that the samples are converted into a more irregular crystal structure. All these results implied that the waste hair mass could be used as an adsorbant material.

Porous Cu-14 wt% Co with aligned pores is produced by a freeze drying and sintering process. Unidirectional freezing of camphene slurry with CuO-Co3O4 powders is conducted, and pores in the frozen specimens are generated by sublimation of the camphene crystals. The dried bodies are hydrogen-reduced at 500oC and sintered at 800oC for 1 h. The reduction behavior of the CuO-Co3O4 powder mixture is analyzed using a temperature-programmed reduction method in an Ar-10% H2 atmosphere. The sintered bodies show large and aligned parallel pores in the camphene growth direction. In addition, small pores are distributed around the internal walls of the large pores. The size and fraction of the pores decrease as the amount of solid powder added to the slurry increases. The change in pore characteristics according to the amount of the mixed powder is interpreted to be due to the rearrangement and accumulation behavior of the solid particles in the freezing process of the slurry.

The design and fabrication of catalysts with low-cost and high electrocatalytic activity for the oxygen evolution reaction (OER) have remained challenging because of the sluggish kinetics of this reaction. The key to the pursuit of efficient electrocatalysts is to design them with high surface area and more active sites. In this work, we have successfully synthesized a highly stable and active NiCo2S4 nanowire array on a Ni-foam substrate (NiCo2S4 NW/NF) via a two-step hydrothermal synthesis approach. This NiCo2S4 NW/NF exhibits overpotential as low as 275 mV, delivering a current density of 20 mA cm-2 (versus reversible hydrogen electrode) with a low Tafel slope of 89 mV dec-1 and superior long-term stability for 20 h in 1M KOH electrolyte. The outstanding performance is ascribed to the inherent activity of the binder-free deposited, vertically aligned nanowire structure, which provides a large number of electrochemically active surface sites, accelerating electron transfer, and simultaneously enhancing the diffusion of electrolyte.

The emergence of green methods for the synthesis of graphene-based composites became the gateway for the solution of pollution and economic synthetic methods. Herein, we reported a single step in situ synthesis of reduced graphene oxide sheets decorated with silver nanoparticles (CRG–Ag nanocomposite) using custard apple leaf extract as an effective reducing and stabilizing agent. The ultraviolet–visible, Fourier transform infrared and Raman techniques revealed a primary confirmation about the formation of the said nanocomposite. The X-ray diffraction studies confirmed the face-centred cubic crystal structure of silver nanoparticles (Ag NPs) of 30 nm in size. The high-resolution scanning electron microscope spectra revealed the uniform distribution of Ag NPs on the graphene sheets. This simple, novel and rapid approach enabled a facile production of homogeneously deposited Ag NPs on graphene sheets. Thus synthesized CRG–Ag nanocomposite showed excellent photocatalytic efficiency of 96% in 2 h under sunlight using methylene blue as a model pollutant.

The study aims to use asphaltene particles (As) extracted from natural bitumen to synthesize activated carbon (ACAs). The asphaltene particles were mixed with a fixed weight of potassium hydroxide (KOH) as an activating agent, preheated to 600 °C, and then treated with 15% hydrofluoric acid (HF). The methylene blue (MB) 20 mg/l was used to determine the adsorption capacity of ACAs and reactivated carbon (RACAs). The morphology of ACAs and its components were characterized using scanning electron microscopy–energy dispersive X-ray (SEM–EDX) and Fourier-transform infrared spectroscopy (FTIR). The study included the application of adsorption isotherms Freundlich and Langmuir on the experimental data of the studied systems. The yield of ACAs was 92% of the raw material. The activated carbon displayed high adsorption capacity and can be reprocessed after reactivation using microwave radiation. The active surface area of ACAs is found to be 970 m2/g. The effectiveness and adsorption ability of ACAs and RACAs, as proven by its adsorption capacity (218.15 and 217.907 mg/g) for MB, demonstrate that ACAs and RACAs have a large external surface area and an extensive array of pores. The ACAs are most sensitive at 30 °C and neutral pH. The results also showed that the isotherms have a good fit to the experimented data.

Fluorescent nanoparticles are characterized by their unique properties such as luminescence, optical transparency, and sensitivity to various chemical environments. For example, semiconductor nanocrystals (quantum dots), which are nanophosphors doped with transition metal or rare earth ions, can be classified as fluorescent nanoparticles. Tuning their optical and physico-chemical properties can be carried out by considering and taking advantage of nanoscale effects. For instance, quantum confinement causes a much higher fluorescence with nanoparticles than with their bulk counterparts. Recently, various types of fluorescent nanoparticles have been synthesized to extend their applications to other fields. In this study, State-of-the-art fluorescent nanoparticles are reviewed with emphasis on their analytical and anti-counterfeiting applications and synthesis processes. Moreover, the fundamental principles behind the exceptional properties of fluorescent nanoparticles are discussed.

이 연구는 그간 수행된 중도입국청소년의 교육 경험을 다룬 연구 중 질적 연구를 선택하여 질적 메타 분석을 실시하고 중도입국청소년들의 교육 적응 과정에서의 위험요인과 보호요인은 무엇인지 살펴보고자 하였다. 질적 메타분석방법은 유사한 주제에 대하여 수행된 질적 연구물을 선정하여 종합 분석함으로써 연구결과의 해석을 확장하는데 기여한다. 분석을 위해 학술연구정보서비스(RISS)를 활용하여 주제어 검 색을 통해 2010년부터 2019년까지 출간된 등재후보지 이상의 논문을 검색하였고, 분석대상으로 최종 선 정된 연구 논문은 총 13편이다. 선정된 개별 연구물에 대해서는 연구의 목적, 연구참가자, 주요 연구주제 들에 대해 살펴보았다. 연구들 간 비교·종합에서는 각 연구에 참여한 중도입국청소년의 배경 특성과 이주 계기 등을 종합하여 제시하였다. 그리고 각 연구의 연구결과를 비교하고 종합하는 과정에서 중도입국청소 년의 교육관련 경험을 이들의 적응에 부정적 측면으로 작용하는 위험요인과 적응을 돕는 보호요인으로 범 주화하였으며, 각 하위 범주는 개인차원, 가족차원, 학교/교육기관, 사회문화 차원으로 구분하여 개별 연구 에서 제시한 세부 내용을 분류하고 재구성하였다. 이러한 과정을 통해 중도입국청소년의 교육 적응을 도 울 수 있는 지원방안 모색에 시사점을 제공하고자 하였다.

Effective control of the heat generated from electronics and semiconductor devices requires a high thermal conductivity and a low thermal expansion coefficient appropriate for devices or modules. A method of reducing the thermal expansion coefficient of Cu has been suggested wherein a ceramic filler having a low thermal expansion coefficient is applied to Cu, which has high thermal conductivity. In this study, using pressureless sintering rather than costly pressure sintering, a polymer solution synthesis method was used to make nano-sized Cu powder for application to Cu matrix with an AlN filler. Due to the low sinterability, the sintered Cu prepared from commercial Cu powder included large pores inside the sintered bodies. A sintered Cu body with Zn, as a liquid phase sintering agent, was prepared by the polymer solution synthesis method for exclusion of pores, which affect thermal conductivity and thermal expansion. The pressureless sintered Cu bodies including Zn showed higher thermal conductivity (180 W/m·K) and lower thermal expansion coefficient (15.8×10−6/℃) than did the monolithic synthesized Cu sintered body.

MoO3 metal oxide nanostructure was formed by hydrothermal synthesis, and a perovskite solar cell with an MoO3 hole transfer layer was fabricated and evaluated. The characteristics of the MoO3 thin film were analyzed according to the change of hydrothermal synthesis temperature in the range of 100 ℃ to 200 ℃ and mass ratio of AMT : nitric acid of 1 : 3 ~ 15 wt%. The influence on the photoelectric conversion efficiency of the solar cell was evaluated. Nanorod-shaped MoO3 thin films were formed in the temperature range of 150 ℃ to 200 ℃, and the chemical bonding and crystal structure of the thin films were analyzed. As the amount of nitric acid added increased, the thickness of the thin film decreased. As the thickness of the hole transfer layer decreased, the photoelectric conversion efficiency of the perovskite solar cell improved. The maximum photoelectric conversion efficiency of the perovskite solar cell having an MoO3 thin film was 4.69 % when the conditions of hydrothermal synthesis were 150 ℃ and mass ratio of AMT : nitric acid of 1 : 12 wt%.

Synthesis of composite powders for the Fe2O3-Zn system by mechanical alloying (MA) has been investigated at room temperature. Optimal milling and heat treatment conditions to obtain soft magnetic composite with fine microstructure were investigated by X-ray diffraction, differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM) measurement. It is found that α-Fe/ZnO composite powders in which ZnO is dispersed in α-Fe matrix can be obtained by MA of Fe2O3 with Zn for 4 hours. The change in magnetization and coercivity also reflects the details of the solid-state reduction process of hematite by pure metal of Zn during MA. Densification of the MA powders was performed in a spark plasma sintering (SPS) machine at 900 ~ 1,000 ℃ under 60 MPa. Shrinkage change after SPS of sample MA'ed for 5 hrs was significant above 300 ℃ and gradually increased with increasing temperature up to 800 ℃. X-ray diffraction results show that the average grain size of α-Fe in the α-Fe/ZnO composite sintered at 900 ℃ is in the range of 110 nm.