본 연구에서는 산 폐수에서 효율적인 산-금속이온 분리를 위한 전기투석 공정에 적용할 수 있는 1가 이온에 대한 높은 선택성을 가진 양이온 교환막의 제조에 관한 연구를 수행하였다. 설폰산기를 가진 sodium 4-vinylbenzenesulfonate (NaSS), 포스폰산기를 가진 vinylphosphonic acid (VPA) 단량체 및 가교제를 비대칭 구조의 다공성 지지체에 충진하고 in-situ 광중합을 통해 세공충진 양이온 교환막을 제조하였다. 제조된 세공충진 양이온 교환막은 상용막 대비 이온교환용량이 다소 낮았으나 실제 응용에 적합한 수준의 전기적 저항 및 기계적 물성을 나타내었다. 다양한 NaSS:VPA 몰 비율로 제조된 세공충진 양이온 교환막과 상용막(CSE, Astom, Japan)의 H+/Fe2+ 혼합용액에서의 선택투과도를 측정한 결과 NaSS:VPA = 25:75 조건에서 가장 우수한 선택투과도를 확인하였으며 이는 상용막 대비 10 이상 높은 값이었다. 또한 최적 조건의 제조막 을 이용한 H+/Fe2+ 혼합용액의 전기투석 결과 상용막 대비 우수한 산-금속 이온 분리 성능을 확인할 수 있었다. 이온전도성이 우수한 설폰산기와 금속이온에 대한 결합력이 강한 포스폰산을 함께 도입한 양이온 교환막은 Fe2+ 이외에도 산 폐액으로부터 다양한 유가 금속이온을 분리하는 데 효과적일 것으로 기대된다.

In order to maximize the function and increase the compatibility of silicone hydrogel lens, this study compared and analyzed the properties of Amino modified silicone oil using mini and microemulsion technique, respectively. Optical and physical properties were evaluated by spectral transmittance, refractive index, water content, oxygen transmittance and contact angle measurements to evaluate the performance of the manufactured hydrogel lens. The spectral transmittance results revealed the copolymerization method lens showed 31 % of the visible light area, which did not satisfy the basic optical properties. However, the lens using the mini and microemulsion materials showed more than 90 % of the visible light area, satisfying the optical characteristics. In addition, all physical properties were superior to a basic hydrogel lens. The mini and microemulsion techniques effectively improved the stability and function of the ophthalmic hydrogel lens and are considered a promising ways of manufacturing an ophthalmic hydrogel contact lens with increased compatibility and stability.

In this study, a core-shell powder and sintered specimens using a mechanically alloyed (MAed) Ti-Mo powder fabricated through high-energy ball-milling are prepared. Analysis of sintering, microstructure, and mechanical properties confirms the applicability of the powder as a sputtering target material. To optimize the MAed Ti-Mo powder milling process, phase and elemental analyses of the powders are performed according to milling time. The results reveal that 20 h of milling time is the most suitable for the manufacturing process. Subsequently, the MAed Ti-Mo powder and MoO3 powder are milled using a 3-D mixer and heat-treated for hydrogen reduction to manufacture the core-shell powder. The reduced core-shell powder is transformed to sintered specimens through molding and sintering at 1300 and 1400oC. The sintering properties are analyzed through X-ray diffraction and scanning electron microscopy for phase and porosity analyses. Moreover, the microstructure of the powder is investigated through optical microscopy and electron probe microstructure analysis. The Ti-Mo core-shell sintered specimen is found to possess high density, uniform microstructure, and excellent hardness properties. These results indicate that the Ti-Mo core-shell sintered specimen has excellent sintering properties and is suitable as a sputtering target material.

An extract of fresh guava leaves (Psidium guajava) was used as a green carbon precursor to fabricate blue fluorescent carbon quantum dots (GCQDs) by hydrothermal process. The GCQDs show bright blue fluorescence emission under UV light with an excitation wavelength of 350 nm and emission at 450 nm. The physical structure of GCQDs was characterized by Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), High-resolution transmission electron microscope (HR-TEM) and atomic force microscopy (AFM). GCQDs 80 μg inhibited the growth of waterborne pathogens Escherichia coli and Salmonella typhi. We also investigated the catalytic activity of the GCQDs on the removal of two azo dyes, namely Congo red and bromophenol blue, with and without NaBH4. The GCQDs showed an excellent reduction of color intensity of both dyes without NaBH4 within 30 min of treatment.

Laser cladding a surface treatment process that grants superior characteristics such as toughness, hardness, and corrosion resistance to the surface, and rebuilds cracked molds; as such, it can be a strong tool to prolong service life of mold steel. Furthermore, compared with the other similar coating processes – thermal spray, etc., laser cladding provides superior bonding strength and precision coating on a local area. In this study, surface characteristics are studied after laser cladding of low carbon steel using 18%Cr-2.5%Ni-Fe powder (Rockit404), known for its high hardness and excellent corrosion resistance. A diode laser with wavelength of 900-1070 nm is adopted as laser source under argon atmosphere; electrical power for the laser cladding process is 5, 6, and 10 kW. Fundamental surface characteristics such as crossectional microstructure and hardness profile are observed and measured, and special evaluation, such as a soldering test with molten ALDC12 alloy, is conducted to investigate the corrosion resistance characteristics. As a result of the die-soldering test by immersion of low carbon alloy steel in ALDC12 molten metal, the clad layer's soldering thickness decreases.

To meet the increased performance and cost requirements of commercial supercapacitor, a N and O self-doped hierarchical porous carbon is fabricated via a green and simple self-activation route utilizing leaves of wild hollyhock as raw materials. Comparing to commercial activated carbon, the reported material exhibits some marked merits, such as simple and green fabrication process, low cost, and superior capacitance performance. The specific surface area of the obtained N and O codoped hierarchical porous carbon arrives 954 m2 g−1, and the content of the self-doped nitrogen and oxygen reaches 2.64 at.% and 7.38 at.%, respectively. The specific capacitance of the obtained material reaches 226 F g− 1 while the specific capacitance of the symmetric supercapacitor arrives 47.3 F g− 1. Meanwhile, more than 90.3% of initial specific capacitance is kept under a current density of 20 A g− 1, and no arresting degradation is observed for capacitance after 5000 times cycle, perfectly demonstrating the excellent cycle and rate capability of the obtained material. The obtained N and O co-doped hierarchical porous carbon are expected to be an ideal substitution for commercial activated carbon.

환경오염과 화석연료의 문제로 인한 2차 에너지 변환 및 저장 장치의 개발이 활발하게 진행되고 있다. 이러한 에너지 변환장치들은 전기화학적 시스템을 기본으로 운영되고 있으며 이온교환막은 각 공정의 성능을 결정짓는 중요한 요소이다. 따라서 에너지 시스템의 효율 증대 및 성능 향상을 위해서는 적합한 물성을 갖는 이온교환막 개발이 필요하다. 이러한 이온교환막은 크게 양이온교환막, 음이온교환막, 바이폴라막으로 분류되고 있으며, 이들 막들은 화학적, 물리적, 형태학적 특성에 따라 다양한 용도을 갖고 있다. 본 총설에서는 이온교환막의 주요한 특징과 함께 이들의 제조 방법에 대해 기술했다. 이어서 이온교환막을 이용하여 최근 개발되고 있는 전기화학 시스템에 기반을 둔 역전기 투석, 레독스 흐름 전지, 수전해 공정에 대해서 소개하고, 각 에너지 공정에서 이온교환막이 갖는 역할과 조건에 대해서 설명하였다.

We report on stretchable electrochromic films of poly(3-hexylthiophene) (P3HT) fabricated on silver nanowire (AgNW) electrodes. AgNWs electrodes are prepared on polydimethylsiloxane (PDMS) substrates using a spray coater for stretchable electrochromic applications. On top of the AgNW electrode, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is introduced to ensure a stable resistance over the electrode under broad strain range by effectively suppressing the protrusion of AgNWs from PDMS. This bilayer electrode exhibits a high performance as a stretchable substrate in terms of sheet resistance increment by a factor of 1.6, tensile strain change to 40%, and stretching cycles to 100 cycles. Furthermore, P3HT film spin-coated on the bilayer electrode shows a stable electrochromic coloration within an applied voltage, with a color contrast of 28.6%, response time of 4-5 sec, and a coloration efficiency of 91.0 cm2/C. These findings indicate that AgNWs/PEDOT:PSS bilayer on PDMS substrate electrode is highly suitable for transparent and stretchable electrochromic devices.

The gas sensor is essential to monitoring dangerous gases in our environment. Metal oxide (MO) gas sensors are primarily utilized for flammable, toxic and organic gases and O3 because of their high sensitivity, high response and high stability. Tungsten oxides (WO3) have versatile applications, particularly for gas sensor applications because of the wide bandgap and stability of WO3. Nanosize WO3 are synthesized using the hydrothermal method. Asprepared WO3 nanopowders are in the form of nanorods and nanorulers. The crystal structure is hexagonal tungsten bronze (MxWO3, x =< 0.33), characterized as a tunnel structure that accommodates alkali ions and the phase stabilizer. A gas detection test reveals that WO3 can detect acetone, butanol, ethanol, and gasoline. This is the first study to report this capability of WO3.

Graphene has shown exceptional properties for high performance devices due to its high carrier mobility. Of particular interest is the potential use of graphene nanoribbons as field-effect transistors. Herein, we introduce a facile approach to the fabrication of graphene nanoribbon (GNR) arrays with ~200 nm width using nanoimprint lithography (NIL), which is a simple and robust method for patterning with high fidelity over a large area. To realize a 2D material-based device, we integrated the graphene nanoribbon arrays in field effect transistors (GNR-FETs) using conventional lithography and metallization on highly-doped Si/SiO2 substrate. Consequently, we observed an enhancement of the performance of the GNRtransistors compared to that of the micro-ribbon graphene transistors. Besides this, using a transfer printing process on a flexible polymeric substrate, we demonstrated graphene-silicon junction structures that use CVD grown graphene as flexible electrodes for Si based transistors.

Cu-Mn compacts are fabricated by the pulsed current activated sintering method (PCAS) for sputtering target application. For fabricating the compacts, optimized sintering conditions such as the temperature, pulse ratio, pressure, and heating rate are controlled during the sintering process. The final sintering temperature and heating rate required to fabricate the target materials having high density are 700oC and 80oC/min, respectively. The heating directly progresses up to 700oC with a 3 min holding time. The sputtering target materials having high relative density of 100% are fabricated by employing a uniaxial pressure of 60 MPa and a sintering temperature of 700oC without any significant change in the grain size. Also, the shrinkage displacement of the Cu-Mn target materials considerably increases with an increase in the pressure at sintering temperatures up to 700oC.

GNPs have several excellent mechanical properties including high strength, a good young’s modulus, thermal conductivity, corrosion resistance, electronic shielding, etc. In this study, CF/GNP/Epoxy composites were manufactured using GNP weight ratios of 0.15 wt%, 0.3 wt%, 0.5 wt%, 0.7 wt% and 1 wt%. The composites were manufactured with a mechanical method (3-roll-mill). Tensile, impact and wear tests were performed according to ASTM standards D3039, D256 and D3181, respectively. The results show that the CF/GNP0.3wt%/Epoxy composites have good mechanical properties, e.g., tensile strength and impact and wear resistance. In this study, both carbon fabric and GNPs were used as reinforcements in the composites. The mechanical properties increased and weight loss decreased as the GNP content in the resin films was increased.