Microwave Characteristics Analysis of Typical Photosensitive Material InP under Weak Light Irradiation Based on Quasi-Optical Resonator

Yafeng Li,En Li,Chengyong Yu,Chong Gao,Gaofeng Guo,Yong Gao 대한금속·재료학회 2020 ELECTRONIC MATERIALS LETTERS Vol.16 No.2

In this paper, the microwave characteristics of typical photosensitive material InP under diff erent light irradiation are studied. The measurement sensor is a refl ection-type hemispherical quasi-optical resonator with an operating frequency range from 20to 40 GHz, an operating mode of TEM 00q , and a quality factor of 18,000 or more. For the short-time irradiation experiment,the variation of InP microwave characteristics with the irradiation power of 20 mW, 60 mW, 100 mW, and 200 mW, is studiedby frequency-domain and time-domain scanning methods, respectively. The measurement results indicate that the microwavecharacteristics of InP change signifi cantly even under weak light irradiation. Taking 100 mW and 200 mW irradiation poweras examples, the long-time irradiation experiment performed on InP lasting 1.5 min is carried out. The measurement resultcurves clearly show the infl uence of the thermal and non-thermal eff ects on the InP microwave characteristics at the instantof the monochrome light source opening and closing and during irradiation. Furthermore, the temperature distribution ofInP during 200 mW irradiation is real-time imaged by a thermal infrared imager to verify the existence of thermal eff ectduring irradiation. The measurement results are in good agreement with the theoretical analysis.

Application of microwave-irradiation technique in deglycosylation of ginsenosides for improving apoptosis induction in human melanoma SK-MEL-2 cells

Choi, Pilju,Kim, Kwantae,Kim, Taejung,Park, Young-Tae,Song, Bong Geun,Shin, Myoung-Sook,Kim, Yong Ho,Hwang, Gwi Seo,Kang, Ki Sung,Ham, Jungyeob Pergamon Press 2019 Bioorganic & medicinal chemistry letters Vol.29 No.3

<P><B>Abstract</B></P> <P>To increase the contents of medicinally effective ginsenosides, we used high-temperature and high-pressure thermal processing of ginseng by exposing it to microwave irradiation. To determine the anti-melanoma effect, the malignant melanoma SK-MEL-2 cell line was treated with an extract of microwave-irradiated ginseng. Microwave irradiation caused changes in the ginsenoside contents: the amounts of ginsenosides Rg1, Re, Rb1, Rb2, Rc, and Rd were disappeared, while those of less polar ginsenosides, such as Rg3, Rg5, and Rk1, were increased. In particular, the contents of Rk1 and Rg5 markedly increased. Melanoma cells treated with the microwave-irradiated ginseng extract showed markedly increased cell death. The results indicate that the microwave-irradiated ginseng extract induced melanoma cell death via the apoptotic pathway and that the cytotoxic effect of the microwave-irradiated ginseng extract is attributable to the increased contents of specific ginsenosides.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Microwave irradiation facilitate deglycosylation of ginsenosides. </LI> <LI> Microwave irradiation caused changes in the ginsenoside contents. </LI> <LI> Less-polar ginsenosides induce apoptosis in melanoma. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effect of Microwave Irradiation on Crystallinity and Pasting Viscosity of Corn Starches Different in Amylose Content

Su-Jin Lee,Kawaljit Singh Sandhu,Seung-Taik Lim 한국식품과학회 2007 Food Science and Biotechnology Vol.16 No.5

Moisture content of normal, waxy, and high amylose corn starches was adjusted to 10-35%, and irradiated in a microwave oven. The effect of microwave irradiation on the crystalline structure of starch was measured by using a differential scanning calorimetry (DSC), and X-ray diffractometry. Pasting viscosity profile was also determined by using a rapid viscoanalyzer (RVA). For all the 3 types of starches tested, the rate of temperature increase by the microwave irradiation was faster and more rapidly reached the maximum temperature of the pressure bomb (120℃) when the moisture content was higher. X-ray diffraction and DSC data revealed that the microwave irradiated starch underwent partial disruption of crystalline structure. RVA studies showed that the irradiation caused significant reductions in maximal viscosity and breakdown, whereas pasting temperature was increased. Overall trends revealed that the microwave irradiation on the starch containing limited moisture content (less than 35%) provided the effects similar to the heat moisture treatment. These effects became more significant when the moisture content was higher. Compared to waxy corn starch, normal, and high amylose corn starches appeared to be more susceptible to the microwave irradiation.

Synthesis of zinc oxide semiconductors-graphene nanocomposites by microwave irradiation for application to gas sensors

Kim, Hyoun Woo,Kwon, Yong Jung,Mirzaei, Ali,Kang, Sung Yong,Choi, Myung Sik,Bang, Jae Hoon,Kim, Sang Sub Elsevier Sequoia 2017 Sensors and actuators. B Chemical Vol.249 No.-

<P><B>Abstract</B></P> <P>Microwave (MW) irradiation has obtained extensive importance in the field of synthesis and treatment of nanoparticles, because of its faster, cleaner and cost effectiveness than the other conventional and wet chemical methods. In this study, ZnO/graphene nanocomposites were prepared and subsequently post-treated by MW irradiation. Responses of the MW irradiated ZnO/graphene nanocomposites sensors were tested towards various gases including NO<SUB>2</SUB>, ethanol, acetone, toluene and CO and the results were compared with those of pristine ZnO and ZnO/graphene sensors without MW irradiation. It was demonstrated that the MW irradiated sensor had much higher response particularly to NO<SUB>2</SUB> gas along with superior selectivity and shorter response/recovery times in comparison to unirradiated ZnO/graphene and pristine ZnO sensors. The possible underlying mechanism of this behavior is discussed in detail, mainly in terms of the MW-induced surface defects and the generation of finer ZnO nanoparticles. The results obtained demonstrated the beneficial effect of MW irradiation for enhancing the NO<SUB>2</SUB>-gas sensing behavior of ZnO/graphene nanocomposites, opening a new door not only to a novel synthesis of semiconductors/graphene nanocomposites, but also to a cost-effective way of improving their sensing capabilities.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ZnO/graphene nanocomposites were prepared by microwave (MW) irradiation. </LI> <LI> MW irradiated sensor had much higher sensing performances particularly to NO<SUB>2</SUB> gas, in comparison to unirradiated ZnO/graphene and pristine ZnO sensors. </LI> <LI> The possible underlying mechanism is explained in terms of the MW-induced surface defects and the generation of finer ZnO nanoparticles. </LI> </UL> </P>

Microwave Heating Characteristics of Magnetite Ore

Ramaraghavulu Rajavaram,Jaehong Lee,Joon Seok Oh,Han Gyeol Kim,Joonho Lee 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.6

The heating characteristics of magnetite ore under microwave irradiation were investigated as a function ofincident microwave power, particle size, and magnetite ore mass. The results showed that the heating rate ofmagnetite ore is highly dependent on microwave power and magnetite ore mass. The maximum heating ratewas obtained at a microwave irradiation power of 1.70 kW with a mass of 25 g and particle size between53-75 μm. The volumetric heating rate of magnetite ore was investigated by measuring the temperature at differentdepths during microwave irradiation. Microwave irradiation resulted in modification of the microstructure of themagnetite ore, but new phases such as FeO or Fe2O3 were not formed. In addition, the crystal size decreasedfrom 115 nm to 63 nm after microwave irradiation up to 1573 K.

마이크로파 추출법을 이용한 방사선 조사 대두의 Hydrocarbons 분석 전처리조건 최적화

이정은 ( Jeong Eun Lee ),권중호 ( Joong Ho Kwon ) 한국유화학회 2013 한국응용과학기술학회지 Vol.30 No.4

지질 함량이 많은 식품에 방사선 조사여부 판별방법으로 적용가능한 hydrocarbons법의 전처리 추출공정을 개선하고자, 추출시간을 효율화 하고 추출용매의 사용을 줄일 수 있는 마이크로웨이브 추출법을 적용하였다. 국제 교역량이 가장 높은 농산물중 대두를 대상으로 방사선 조사(4 kGy)를 하여 hydrocarbons 분석에 대한 전처리 조건을 최적화하고자 하였다. 예측된 대두의 최적 추출범위는 extraction time 1.3-3.2분, microwave power 61-133 W로 나타났고, 예측된 범위에서 임의점을 설정하여 회귀식에 대입하여 최적값을 예측하였을 때 값은 microwave power와 extraction time이 각각 97 W과 2.2 분으로 확인되었다. 방사선조사 허가식품에 대해서 검지법의 분석결과의 정확성과 더불어 신속성이 요구되는 상황에서 hydrocarbons검지법 적용이 가능한 대두를 대상으로 MAE (micarowave-assisted extraction) 추출법을 적용한다면, 식품공전상의 현행 추출전처리(12-24시간)에 따른 분석시간을 줄이고 추출공정 개선이 가능할 것으로 본다. Microwave-assisted extraction, MAE, which is known as less time and less solvent than current extraction methods, was applied to hydrocarbons extraction from irradiated soybean. Among the transported agricultural products, soybean was selected as representative samples for possible application of irradiated treatment and identification of radiation-induced markers. Using 4 kGy-irradiated soybean, different microwave extraction conditions (extraction time and microwave power) were applied and the changes in hydrocarbon concentrations were monitored. The predicted optimum extracted condition for hydrocarbon analysis of soybean was found to be microwave extraction with a microwave power of 97 W and extraction time of 2.2 min. This extraction time was significantly lower compared to the common extraction time of 12-24hr.

마이크로웨이브를 이용한 아스팔트 혼합물 자가회복 특성 실내 연구

김성운,김광우,정운규 한국아스팔트학회 2023 한국아스팔트학회지 Vol.13 No.2

Asphalt has the characteristic of changing phases into solid, viscoelastic, and liquid depending on temperature. Asphalt becomes brittle at low temperatures in the winter, causing cracks, and becomes fluid and deforms at high temperatures in the summer. Asphalt has fluidity as temperature rises and has the property of moving to cracks inside the pavement and sealing. Research on restoring road performance using this characteristic (asphalt self-healing) has been actively conducted. In this study, various tests were conducted to confirm the self-healing properties of asphalt using microwave irradiation in the laboratory. The flexural strength and indirect tensile strength before and after microwave irradiation were compared to analyze the different strength recovery ratio due to microwave irradiation. As a result of the study, it was confirmed that microwave irradiation is effective in recovering the strength of asphalt pavement, and that the strength recovery ratio of asphalt mixtures using SMA mixtures with high asphalt content and materials with heat conduction characteristics was high.

Performance assessment of microwave treated WC insert while turning AISI 1040 steel

Durwesh Jhodkar,M. Amarnath,H. Chelladurai,J. Ramkumar 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.6

This study attributed to post treatment of tungsten carbide (WC) inserts using microwave irradiation. Tungsten carbide inserts were subjected to microwave radiation (2.45 GHz) to enhance its performance in terms of reduction in tool wear rate, cutting force surface roughness and improvement in tool life. Performance of tungsten carbide insert is very much affected by machine operating parameters i.e. speed, feed and depth of cut. An attempt has been made to investigate the effects of machining parameters on microwave treated tool inserts. This paper describes the comparative study of machining performance of untreated and microwave treated WC tool inserts used for turning of AISI 1040 steel. Machining performance has been evaluated in terms of flank wear, cutting force, surface roughness, tool wear mechanisms. Critical examinations of tool wear mechanisms and improvements in metallurgical properties such as microstructural change, phase activation of WC grains were identified using scanning electron microscope (SEM). Results obtained from the turning using the microwave treated tool inserts showed a significant reduction tool wear thereby enhancing the surface quality of workpiece.

Effect of Successive Processing on Properties of Ligno-Cellulosic Micro-Fines from Pinus densiflora with Microwave Irradiation

김강재,류지애,엄태진 한국펄프·종이공학회 2020 펄프.종이기술 Vol.52 No.2

This study compares the chemical characteristics of lingo-cellulosic micro-fines (LCMFs) obtained from successive microwave-assisted organosolv-processed wood powders. Both the yields and the Klason lignin (KL) contents of the LCMFs were found to decrease dramatically following the first microwave-assisted organosolv process. However, the KL content of successive microwave-assisted organosolved-LCMFs decreased only slightly compared with the LCMFs from first process. Moreover, after the first microwave-assisted organosolv process, the particle size of the LCMFs decreased dramatically, but resulted in little change after successive microwave-assisted organosolv processes. The chemical composition of the LCMFs was characterized by the elution of most of the hemicellulose and lignin during the first microwave-assisted organosolv process. In addition, the process significantly reduced the monosaccharide content of hemicellulose, whereas the crystallinity index of the first LCMFs increased. However, in subsequent repetitions of the microwave-assisted organosolv process, the similarities between the crystallinity index, vanillin content, and monosaccharide content of the LCMFs were maintained.

Microwave-assisted functionalization of polyurethane surface for improving blood compatibility

Deqiang You,Mei Tu,Rong Zeng,Hao Liang,Weizhong Mai,Jianhao Zhao,Zhengang Zha 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.5

In order to improve the hemocompatibility of polyurethane (PU), we report a rapid and efficient two-step approach to graft poly(ethylene glycol) (PEG) onto PU surface by a microwave-assisted method,involving diphenylmethane diisocyanate (MDI) – functionalization and subsequent PEG coupling. Compared with conventional heating, the effects of solvent, time and MDI concentrations on the microwave-assisted MDI-functionalization, and the effect of time on the microwave-assisted PEG coupling were studied. PEGs with different molecular weights were successfully grafted onto PU surface under the optimum microwave-assisted conditions within only 20 min, and characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and chemical titration. The hydrophilicity and in vitro blood compatibility of the surfaces were evaluated by water contact angle measurements, blood coagulation time (whole blood clotting time and prothrombin time) and platelet adhesion tests, respectively. All the PU-PEG surfaces had improved surface wettability and hemocompatibility. The results suggested that microwave-assisted functionalization may be a promising method for rapidly and effectively decorating polyurethane surfaces.