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Sergio Lins de-Azevedo-Vaz,João Victor Pereira Machado,Teresa Cristina Rangel Pereira,Deborah Queiroz Freitas 대한영상치의학회 2019 Imaging Science in Dentistry Vol.49 No.1
Purpose: To determine whether calcified carotid atherosclerotic plaques (CCAPs) and mineralized laryngeal cartilages (MLCs) were more frequently detected on digital or film-based panoramic radiographs. The clinical relevance of this question is that some radiopacities seen on digital radiographs may correspond to medium-density tissues that are not necessarily mineralized. Materials and Methods: Data were collected from panoramic radiographs and the respective reports issued by 2 private oral radiology centers. A total of 388 radiographs and reports were divided into film-based (group A) and digital (group D) radiographs. The frequencies of CCAPs and MLCs were analyzed using the Fisher exact test, and odds ratios were also calculated (α=1%). Results: The mean age of patients whose reports and radiographs showed CCAPs and/or MLCs ranged from 50.1 to 54.1 years. There was a predominance of females. A higher frequency of CCAPs and MLCs was observed in group D than in group A at both centers (P<0.01). CCAPs and MLCs were detected 4 times more frequently in group D than in group A at one of the centers. Conclusion: CCAPs and MLCs were more frequently detected on digital than on film-based panoramic radiographs. Further studies are needed to determine whether such radiopacities do indeed correspond to mineralized, rather than medium-density, tissues.
The simple and easy way to manufacture counter electrode for dye-sensitized solar cells
Jo-Lin Lan,Yung-Yun Wang,Chi-Chao Wan,Tzu-Chien Wei,Hsien-Ping Feng,Chao Peng,Hai-Peng Cheng,Ya-Huei Chang,Wen-Chi Hsu 한국물리학회 2010 Current Applied Physics Vol.10 No.2
We previously developed poly-N-vinyl-2-pyrrolidone (PVP)-capped Pt nanoclusters on ITO glass via a simple ‘‘2-step dip coating process” as counter electrode for DSSC. This new counter electrode was examined by transmission electron microscopy (TEM), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and current–voltage curve (I–V curve). The TEM results revealed that PVP-capped Pt nanoclusters’ size is about 3 nm, and the amount of Pt deposited on ITO glass is about 5 ㎍/㎠. Comparing with sputtered Pt and Solaronix thermal cluster Pt-catalyst T/SP, the PVP-capped Pt counter electrode has lower amount of Pt deposited on TCO glass,more positive potential of tri-iodide reduction, and better performance for the charge-transfer resistance (RCT) and the cell efficiency (g).
Gan, Lin,Park, Young-Jo,Zhu, Lin-Lin,Go, Shin-Il,Kim, Haneul,Kim, Jin-Myung,Ko, Jae-Woong Elsevier 2016 CERAMICS INTERNATIONAL Vol.42 No.12
<P><B>Abstract</B></P> <P>In this work, we report the enhancement of the optical transmittance of yttria ceramics via a ‘pre-sintering/hot-pressing/hot-isostatic pressing’ multi-step process. The in-line transmittance reaches 78.0% at 400nm and 83.2% at 1100nm with an average grain size of approximately 1µm. This sintering route is derived and upgraded from our previously reported one-step hot-pressing method for the fabrication of transparent yttria ceramics. Through the enhanced strength of the green body by pre-sintering, the formation of cracks and the breaking up of the as-hot-pressed samples can be effectively suppressed, leading to sound or crack-free but less transparent samples. After a post-HIPing treatment, the optical transmittance of the samples with a pre-sintering step was substantially improved to higher levels in the visible and the IR wavelengths compared to that of a sample which does not undergo pre-sintering. The corresponding mechanism was revealed by microstructural analyses.</P>
Zhu, Lin-Lin,Park, Young-Jo,Gan, Lin,Go, Shin-Il,Kim, Ha-Neul,Kim, Jin-Myung,Ko, Jae-Woong North-Holland 2018 Materials letters Vol.219 No.-
<P><B>Abstract</B></P> <P>Transparent magnesium aluminate spinel (MgAl<SUB>2</SUB>O<SUB>4</SUB>) ceramics were successfully fabricated for the first time using commercially available nanopowders without sintering additive by a single hot-press step process. This method does not involve all the complexity of powder, green body pre-treatment and post-treatment, which are commonly used in the fabricating process. Effects of holding time (3–12 h) at the sintering temperature 1500 °C on the transmittance, microstructure and Vickers microhardness are investigated. The highest transmittance is achieved for the sample hot pressed at 1500 °C for 12 h, which exhibits 80.2% at the wavelength of 1100 nm. These results may provide a guide for understanding the microstructural development of transparent spinel without sintering additive.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Pure MgAl<SUB>2</SUB>O<SUB>4</SUB> transparent ceramic was prepared by a single hot-press step. </LI> <LI> The transmittance of the sample at 1500 °C for 12 h reached 80.2% at 1100 nm. </LI> <LI> The Vickers microhardness decreases from 15.1 to 12.5 GPa with holding time from 3 to 12 h. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Gan, Lin,Park, Young-Jo,Zhu, Lin-Lin,Go, Shin-Il,Kim, Haneul,Kim, Jin-Myung,Ko, Jae-Woong Elsevier 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.695 No.-
<P><B>Abstract</B></P> <P>In this work, highly transparent La<SUB>2</SUB>O<SUB>3</SUB>-doped yttria ceramics were fabricated by a hot-pressing method. The effects of the La<SUB>2</SUB>O<SUB>3</SUB> doping concentration (0–17 at.%) on the optical transmittance, microstructures, microhardness, and thermal conductivity levels of the transparent yttria were investigated in an effort to develop a user's choice guide pertaining to the optical, mechanical, and thermal properties. The optimal La<SUB>2</SUB>O<SUB>3</SUB> doping concentration for the optical transmittance was found to be 12 at.%, leading to in-line transmittance levels of 68.9% at 400 nm and 81.9% at 1100 nm (2 mm thick). The microhardness changed from 6.82 to 7.66 GPa and was found to be closely dependent on the grain sizes of the samples, which varied from 3.55 μm to 0.95 with changes in the La<SUB>2</SUB>O<SUB>3</SUB> doping concentration. The biaxial flexure strength of a hot-pressed sample with an average grain size of 1.46 μm exceeded that of a conventionally pressureless-sintered coarse-grained sample (grain size 40.82 μm) by 94.4%. The thermal conductivity showed a significant decrease from 16.40 to 5.71 W/mK with an increase in the La<SUB>2</SUB>O<SUB>3</SUB> doping concentration from 0 to 17 at.%. Potential applications of the transparent yttria ceramics with different compositions were suggested based on the combination of the optical, mechanical, and thermal properties.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Highly transparent La-doped yttria ceramics were prepared by hot pressing. </LI> <LI> Effects of La concentration on transmittance, microstructure were studied. </LI> <LI> Effects of La concentration on thermal conductivity were studied. </LI> <LI> Microhardness and biaxial flexure strength of the samples were studied. </LI> </UL> </P>
Gan, Lin,Park, Young-Jo,Zhu, Lin-Lin,Kim, Ha-Neul,Ko, Jae-Woong,Kim, Hai-Doo Elsevier 2018 Journal of the European Ceramic Society Vol.38 No.11
<P><B>Abstract</B></P> <P>In this work, highly transparent yttria ceramics Φ = 55 mm in size were fabricated by a hot-pressing method with 1 at.% ZrO<SUB>2</SUB> or 12 at.% La<SUB>2</SUB>O<SUB>3</SUB> as a sintering additive. For a 4-mm-thick specimen doped with ZrO<SUB>2</SUB>, the in-line transmittance reaches 71.1% at 400 nm and 80.9% at 1100 nm, and the transmittance of the La<SUB>2</SUB>O<SUB>3</SUB>-doped specimen is comparable to that of the ZrO<SUB>2</SUB>-doped specimen. By means of the relatively low sintering temperature of 1600 °C, the present samples exhibited very fine microstructures (<2 μm), giving rise to excellent mechanical strength levels (∼200 MPa). With regard to the 1 at.% ZrO<SUB>2</SUB>-doped specimen, the combination of high strength and high thermal conductivity (∼10 W/m K) substantially improved parameters related to the thermal shock resistance. The results of this study indicate that the hot-pressed transparent yttria ceramic doped with 1 at.% ZrO<SUB>2</SUB> is optically, mechanically, and thermally suitable for high-temperature IR window applications.</P>
Zhu, Lin-Lin,Park, Young-Jo,Gan, Lin,Kim, Ha-Neul,Ko, Jae-Woong,Kim, Hai-Doo Elsevier 2018 Journal of the European Ceramic Society Vol.38 No.11
<P><B>Abstract</B></P> <P>Sintering-additive-free fine-grained highly transparent Y<SUB>2</SUB>O<SUB>3</SUB> ceramics featuring record-high thermal shock resistance were fabricated using commercial powders via vacuum pre-sintering (1375–1550 °C) followed by hot-isostatic pressing (1450 °C). The sample pre-sintered at 1450 °C provides the optimum microstructure for post HIPing, which resulted in a grain size of 0.64 μm. The transmittance, microhardness and fracture toughness of the thus HIPed sample are 80.8% at 1100 nm and 65.5% at 400 nm (1.2 mm thick), 8.0 ± 0.02 GPa and 1.00 ± 0.06 MPa m<SUP>1/2</SUP>, respectively. The thermal conductivity increases from 13.1 to 16.5 W/m/K with increasing vacuum pre-sinterin Proc. SPIE-Int. Soc. Opt g temperature from 1450 to 1550 °C. This hybrid sintering method realized high thermal conductivity and high strength simultaneously. Consequently, the thermal shock resistance of the HIPed specimen vacuum pre-sintered at 1450 °C in this work is the highest ever reported to the best of our knowledge, which makes the developed material a promising candidate for high-power laser host and IR dome.</P>
Zhu, Lin-Lin,Park, Young-Jo,Gan, Lin,Kim, Ha-Neul,Ko, Jae-Woong,Lee, Jae-Wook,Kim, Hai-Doo Elsevier 2018 Ceramics international Vol.44 No.14
<P><B>Abstract</B></P> <P>It is known that 1.0 at.% is the lowest amount of ZrO<SUB>2</SUB> which can be used for the sintering of well-balanced Y<SUB>2</SUB>O<SUB>3</SUB> ceramics to ensure both transparency and strength. In this work, a highly transparent Y<SUB>2</SUB>O<SUB>3</SUB> ceramic material doped with a reduced amount of ZrO<SUB>2</SUB> (0.5 at.%) was fabricated by means of a hot-press sintering method at a temperature as low as 1600°C using commercial powders. The in-line transmittance of the 0.5 at.% ZrO<SUB>2</SUB>-doped Y<SUB>2</SUB>O<SUB>3</SUB> sample (2 mm thick) is 80.8% at 1100 nm and 72.2% at 400 nm with an average grain size of 1.06 μm. By reducing the ZrO<SUB>2</SUB> content from 1.0 to 0.5 at.%, the thermal conductivity is increased by 18.2% with only a slight decline in the strength and the band gap becomes broader. Consequently, the Hasselman mild-thermal-shock figure of merit of the developed specimen increases by 13.0% overall. These results indicate that this Y<SUB>2</SUB>O<SUB>3</SUB> ceramic has potential for use as a laser host or an infrared window material used on Mach-speed applications.</P>
Zhu, Lin-Lin,Park, Young-Jo,Gan, Lin,Go, Shin-Il,Kim, Ha-Neul,Kim, Jin-Myung,Ko, Jae-Woong Elsevier 2017 CERAMICS INTERNATIONAL Vol.43 No.16
<P><B>Abstract</B></P> <P>In this study, we report highly transparent Er:Y<SUB>2</SUB>O<SUB>3</SUB> ceramics (0–10at% Er) fabricated by a vacuum sintering method using compound sintering additives of ZrO<SUB>2</SUB> and La<SUB>2</SUB>O<SUB>3</SUB>. The transmittance, microstructure, thermal conductivity and mechanical properties of the Er:Y<SUB>2</SUB>O<SUB>3</SUB> ceramics were evaluated. The in-line transmittance of all of the Er:Y<SUB>2</SUB>O<SUB>3</SUB> ceramics (1.2mm thick) exceeds 83% at 1100nm and 81% at 600nm. With an increase in the Er doping concentration from 0 to 10at%, the average grain size, microhardness and fracture toughness remain nearly unchanged, while the thermal conductivity decreases slightly from 5.55 to 4.89W/mK. A nearly homogeneous doping level of the laser activator Er up to 10at% in macro-and nanoscale was measured along the radial direction from the center to the edge of a disk specimen, which is the prominent advantage of polycrystalline over single-crystal materials. Based on the finding of excellent optical and mechanical properties, the compound sintering additives of ZrO<SUB>2</SUB> and La<SUB>2</SUB>O<SUB>3</SUB> are demonstrated to be effective for the fabrication of transparent Y<SUB>2</SUB>O<SUB>3</SUB> ceramics. These results may provide a guideline for the application of transparent Er:Y<SUB>2</SUB>O<SUB>3</SUB> laser ceramics.</P>
Loo, Jo Lin,Ang, Yee Kwang,Yim, Hip Seng Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.1
Objectives: To describe the development and validation of a cancer awareness questionnaire (CAQ) based on a literature review of previous studies, focusing on cancer awareness and prevention. Materials and Methods: A total of 388 Chinese undergraduate students in a private university in Kuala Lumpur, Malaysia, were recruited to evaluate the developed self-administered questionnaire. The CAQ consisted of four sections: awareness of cancer warning signs and screening tests; knowledge of cancer risk factors; barriers in seeking medical advice; and attitudes towards cancer and cancer prevention. The questionnaire was evaluated for construct validity using principal component analysis and internal consistency using Cronbach's alpha (${\alpha}$) coefficient. Test-retest reliability was assessed with a 10-14 days interval and measured using Pearson product-moment correlation. Results: The initial 77-item CAQ was reduced to 63 items, with satisfactory construct validity, and a high total internal consistency (Cronbach's ${\alpha}$=0.77). A total of 143 students completed the questionnaire for the test-retest reliability obtaining a correlation of 0.72 (p<0.001) overall. Conclusions: The CAQ could provide a reliable and valid measure that can be used to assess cancer awareness among local Chinese undergraduate students. However, further studies among students from different backgrounds (e.g. ethnicity) are required in order to facilitate the use of the cancer awareness questionnaire among all university students.