• Title/Summary/Keyword: ATR

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UV-curing Behaviors and Mechanical Properties of UV-cured Polylactic Acid (PLA)

  • Lee, Seung-Woo;Park, Ji-Won;Park, Cho-Hee;Kim, Hyun-Joong;Eom, Young-Geun
    • Journal of the Korean Wood Science and Technology
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    • v.41 no.2
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    • pp.134-140
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    • 2013
  • UV curing was introduced via a chemical treatment by adding small amounts of a hexafunctional acrylic monomer and a photoinitiator to improve the mechanical properties of PLA. This study also employed a semi-interpenetrated structured polymer network through the process of UV-curing. The UV curing behaviors were investigated using FTIR-ATR spectroscopy and gel fraction determination. Also, the tensile strength was investigated with different hexafunctional acrylic monomer contents and UV doses. The results showed that the crosslinking of UV-induced chemically treated PLA started at a low content of hexafunctional acrylic monomer, resulting in a significant improvement of the mechanical properties compared to those of neat PLA due to crosslinking.

Dephosphorylation of DBC1 by Protein Phosphatase 4 Is Important for p53-Mediated Cellular Functions

  • Lee, Jihye;Adelmant, Guillaume;Marto, Jarrod A.;Lee, Dong-Hyun
    • Molecules and Cells
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    • v.38 no.8
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    • pp.697-704
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    • 2015
  • Deleted in breast cancer-1 (DBC1) contributes to the regulation of cell survival and apoptosis. Recent studies demonstrated that DBC is phosphorylated at Thr454 by ATM/ATR kinases in response to DNA damage, which is a critical event for p53 activation and apoptosis. However, how DBC1 phosphorylation is regulated has not been studied. Here we show that protein phosphatase 4 (PP4) dephosphorylates DBC1, regulating its role in DNA damage response. PP4R2, a regulatory subunit of PP4, mediates the interaction between DBC1 and PP4C, a catalytic subunit. PP4C efficiently dephosphorylates pThr454 on DBC1 in vitro, and the depletion of PP4C/PP4R2 in cells alters the kinetics of DBC1 phosphorylation and p53 activation, and increases apoptosis in response to DNA damage, which are compatible with the expression of the phosphomimetic DBC-1 mutant (T454E). These suggest that the PP4-mediated dephosphorylation of DBC1 is necessary for efficient damage responses in cells.

Synthesis and characterization of polyamide membrane for the separation of acetic acid from water using RO process

  • Mirfarah, Hesam;Mousavi, Seyyed Abbas;Mortazavi, Seyyed Sajjad;Sadeghi, Masoud;Bastani, Dariush
    • Membrane and Water Treatment
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    • v.8 no.4
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    • pp.323-336
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    • 2017
  • The main challenge in many applications of acetic acid is acid dehydration and its recovery from wastewater streams. Therefore, the performance of polyamide thin film composite is evaluated to separate acetic acid from water. To reach this goal, the formation of polyamide layer on polysulfone support membrane was investigated via interfacial polymerization (IP) of meta-phenylenediamine (MPD) in water with trimesoyl chloride (TMC) in hexane. Also, the effect of synthesis conditions, such as concentration of monomers and curing temperature on separation of acetic acid from water were investigated by reverse osmosis process. Moreover, the separation mechanism was discussed. The solute permeation was carried out under applied pressure of 5 bar at $25^{\circ}C$. Surface properties of TFC membrane were characterized by ATR-FTIR, SEM and AFM. The performance test indicated that 3.5 wt% of MPD, 0.35 wt% of TMC and curing temperature of $75^{\circ}C$ are the optimum conditions. Moreover, the permeate flux was $4.3{\frac{L}{m^2\;h}}$ and acetic acid rejection was about 43% at these conditions.

The Preparation of a Thermally Responsive Surface by Ion Beam-induced Graft Polymerization

  • Jung, Chang-Hee;Kim, Wan-Joong;Jung, Chan-Hee;Hwang, In-Tae;Choi, Jae-Hak
    • Journal of Radiation Industry
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    • v.6 no.4
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    • pp.317-322
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    • 2012
  • In this study, the preparation of a temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm)-grafted surface was performed using an eco-friendly and biocompatible ion beam-induced surface graft polymerization. The surface of a perfluoroalkoxy (PFA) film was activated by ion implantation and N-isopropylacrylamide (NIPAAm) was then graft polymerized selectively onto the activated regions of the PFA surfaces. Based on the results of the peroxide concentration and grafting degree measurements, the amount of the peroxide groups formed on the implanted surface was dependant on the fluence, which affected the grafting degree. The results of the FT-IR-ATR, XPS, and SEM confirmed that the NIPAAm was successfully grafted onto the implanted PFA. Moreover, the contact angle measurement at different temperatures revealed that the surface of the PNIPAAm-grafted PFA film was temperature-responsive.

Improved performance of polyamide nanofiltration membranes by incorporating reduced glutathione during interfacial polymerization

  • Jiao, Zhiwei;Zhou, Linjie;Wu, Mengyuan;Gao, Kang;Su, Yanlei;Jiang, Zhongyi
    • Korean Journal of Chemical Engineering
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    • v.35 no.12
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    • pp.2487-2495
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    • 2018
  • Inspired by the specific amino acid sequence Asn-Pro-Ala (NPA) of water channel aquaporins (AQPs), we fabricated polyamide (PA) nanofiltration (NF) membranes by introducing reduced glutathione (GSH) in interfacial polymerization (IP) method. Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectrometry (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM), zeta potential and static water contact angle measurement were employed to characterize the chemical composition, morphology, electronegativity and hydrophilicity of the NF membranes. The water flux of GSH/PIP-TMC NF membrane reached $32.00L\;m^{-2}h^{-1}$ at 0.2 MPa, which was approximately twice than that of pristine PIP-TMC NF membrane when the ratio of GHS to piperazidine (PIP) was 40% during IP process. More water channels were built as GSH was embedded into PA layer. The fabricated NF membranes also took on potent rejection for dyes and $Na_2SO_4$. This study presents a simple and facile method to simulate water channels-based biological materials which may find potential application in water treatment.

Fabrication and Properties of Organic Semiconductor CuPccp LB Thin Film (유기 반도체 CuPccp LB초박막의 제작 및 특성)

  • Jho, Mean Jea;Xouyang, Saiyang;Lee, Jin Su;Ahn, Da Hyun;Jung, Chi Sup
    • Journal of Sensor Science and Technology
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    • v.28 no.1
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    • pp.23-29
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    • 2019
  • A copper tetracumylphenoxy phthalocyanine (CuPccp) thin film was formed on an organic insulator film by Langmuir-Blodgett (LB) deposition for gas sensor fabrication. To increase the reproducibility of film transfer, stearyl alcohol was used as a transfer promoter. The structural properties of the CuPccp layers were optically monitored through attenuated total reflection and polarization-modulated ellipsometry techniques. The average thickness of a single layer of the CuPccp LB film was measured to be 2.5 nm. Despite the role of the transfer promoter, the stability of the layer transfer was not sufficient to ensure homogeneity of the LB film. This was probably due to the presence of aggregates in the molecular structure of the CuPccp LB film. Nevertheless, copper phthalocyanine polymorphism can be greatly suppressed by the LB arrangement, which appears to contribute to the improvement of electrical conductivity. The p-type semiconductor characteristics were confirmed by Hall measurements from the CuPccp LB films.

Development of Autonomous Reconnaissance Flight Simulation for Unmanned Aircraft to Derive Flight Operating Condition (자율정찰비행 무인항공기의 비행운영조건 고찰을 위한 비행시뮬레이션 개발)

  • Seok, Min Joon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.47 no.4
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    • pp.266-273
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    • 2019
  • The efficiency and effectiveness of mission performance can be greatly changed according to the operating conditions such as the number of manned aircraft, flight altitude, and so on, in performing search and reconnaissance missions using a large number of small reconnaissance unmanned aerial vehicles. However, it is not easy to determine which operating conditions are most reasonable. Therefore, in this study, we developed an unmanned airplane flight simulation that can detect and identify the target while avoiding collision according to autonomous flight, suggesting a way to derive operating conditions when operating a large number of unmanned aerial vehicles.

Functionalization of PLLA Sheet Using Gamma-ray Irradiation (감마선 이용 친수성 PLLA 시트 기능화 및 특성 평가)

  • Gwon, Hui-Jeong;Jeong, Jin-Oh;Jeong, Sung In;Park, Jong-Seok;Lim, Youn-Mook
    • Journal of Radiation Industry
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    • v.12 no.4
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    • pp.343-348
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    • 2018
  • Preliminary study was perfomed to develop a biocompatible filter material using radiation energy. Electrosppined PLLA nano sheets were surface-modificated with hydrophilic groups(acrylic group) by using radiation. The physico-chemical and morphological characteristics of modified PLLA sheets were measured by ATR, SEM, contact angle, and hydrophilic (acryl group) introduction rate (TBO). As a result, there was no morphological(fiber structure) structure change due to radiation, and it was confirmed that an acrylic group was successfully introduced onto PLLA fiber sheet by radiation.

Resolution Conversion of SAR Target Images Using Conditional GAN (Conditional GAN을 이용한 SAR 표적영상의 해상도 변환)

  • Park, Ji-Hoon;Seo, Seung-Mo;Choi, Yeo-Reum;Yoo, Ji Hee
    • Journal of the Korea Institute of Military Science and Technology
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    • v.24 no.1
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    • pp.12-21
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    • 2021
  • For successful automatic target recognition(ATR) with synthetic aperture radar(SAR) imagery, SAR target images of the database should have the identical or highly similar resolution with those collected from SAR sensors. However, it is time-consuming or infeasible to construct the multiple databases with different resolutions depending on the operating SAR system. In this paper, an approach for resolution conversion of SAR target images is proposed based on conditional generative adversarial network(cGAN). First, a number of pairs consisting of SAR target images with two different resolutions are obtained via SAR simulation and then used to train the cGAN model. Finally, the model generates the SAR target image whose resolution is converted from the original one. The similarity analysis is performed to validate reliability of the generated images. The cGAN model is further applied to measured MSTAR SAR target images in order to estimate its potential for real application.

Crystallinity change of silkworm variety cocoons by heat treatment

  • Bae, Yu Jeong;Noh, Si Kab;Um, In Chul
    • International Journal of Industrial Entomology and Biomaterials
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    • v.42 no.1
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    • pp.7-13
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    • 2021
  • In the present study, the effect of heat treatment on the crystallinity of the outside of silkworm cocoon in nine different silkworm varieties was studied using ATR-FTIR spectroscopy. Additionally, the morphological structure and moisture regain of the cocoon were examined. The silkworm cocoon showed different colors and external features depending on the silkworm variety. Moreover, the thickness of the filament (15.3-27.6 ㎛) and moisture regain of the cocoon (9.0%-11.0%) were quite different depending on the silkworm variety. The crystallinity index of the cocoon outside varied from 52.1% to 56.1%, depending on the silkworm variety. J300 and MO42 showed the highest (56.1%) and the lowest (52.1%) crystallinity index, respectively, indicating that the microstructure of sericin of the outside of the cocoon was affected by the silkworm variety. Regardless of silkworm variety, their crystallinity indexes decreased from 52.1%-56.1% to 49.9%-43.6% depending on the silkworm variety by the heat treatment at 250 ℃. Interestingly, the crystallinity degree decrease was somewhat different depending on the silkworm variety, implying that the cocoon sericin microstructure is strongly influenced by the silkworm variety.