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Highly directional waveguide grating antenna for optical phased array
Han, Kyunghun,Yurlov, Victor,Yu, Nan Ei ELSEVIER 2018 CURRENT APPLIED PHYSICS Vol.18 No.7
<P>A highly directional waveguide grating antenna by patterning top cladding has been proposed. Spatial separation of the grating structure from the waveguide reduces the strength of perturbation to achieve a millimeter-scale emission. The optimized grating structure offers above 70% directionality with 800 nm waveguide width. The vertical field-of-view of 15 degrees is achieved with 100 nm wavelength bandwidth. Thanks to the its simple structure and large critical dimension, the proposed structure is suitable for manufacturing in CMOS foundries with DUV lithography.</P>
Pryamitsyn, Victor,Han, Sung Hyun,Kim, Jin Kon,Ganesan, Venkat American Chemical Society 2012 Macromolecules Vol.45 No.21
<P>We present a strong stretching theory model for microphase segregation of AB + AC block copolymer blends in which the B and C segments possess strongly attractive (hydrogen bonding) interactions. In microphase separated morphologies, we demonstrate that the attraction between the B and the C segments causes a bending force toward the A layers. Such bending forces may induce transitions from lamellar and A-majority cylindrical morphologies in the pure component systems to “inverted” cylindrical and spherical morphologies in blends in which the B and C segments constitute the matrix phase. Similar driving forces may also drive transitions from A-majority spherical phases in pure component systems to highly asymmetric lamellar morphologies in blends. The predictions of our model are in excellent agreement with the trends observed in recent experimental results.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/mamobx/2012/mamobx.2012.45.issue-21/ma301402n/production/images/medium/ma-2012-01402n_0012.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ma301402n'>ACS Electronic Supporting Info</A></P>
An Unusual Cause of Hemoptysis: Congenital Absence of the Right Pulmonary Artery in a Young Male
Chan Victor Siang Hua,Ma Wai Han,Ho Wai Yin,Chan Carmen Wing Sze,Cheung Stephen Chi Wai,Lam Wendy Wai Man 아시아심장혈관영상의학회 2019 Cardiovascular Imaging Asia Vol.3 No.1
Unilateral absent pulmonary artery (UAPA) is rare and can occur in association with cardiovascular anomalies or in isolation. Herein, we describe a case of isolated UAPA in a 14-yearold male patient who presented with hemoptysis secondary to abnormal hypertrophy of collateral vasculature. The patient was successfully treated by endovascular embolization with polyvinyl alcohol particles.
Tribological evaluation of selected biodegradable oils with long chain fatty acids
Ossia, Chinwuba Victor,Han, Hung Gu,Kong, Hosung Emerald Group Publishing Limited 2010 Industrial lubrication and tribology Vol.62 No.1
<B>Purpose</B> - The purpose of this paper is to evaluate local biodegradable oils with long chain fatty acids namely: castor (<I>Ricinus communis</I> L.), jojoba (<I>Simmondsia chinensis</I> L.), olive (<I>Oleo europaea</I> L.), and sunflower (<I>Helianthus annuus</I> L.) oils for lubrication candidacy as a substitute to petroleum mineral oils. <B>Design/methodology/approach</B> - Evaluation criteria includes antiwear, lubricity, and extreme pressure (load carrying capacity) using the four-ball configuration, oxidation induction by pressure differential scanning calorimetry, thermal stability by thermo-gravimetric analyses, and viscometry using relevant American Society of Testing and Materials (ASTM) standards. <B>Findings</B> - The results show that the lubrication films at the interface failed by the decomposition of the metallic soaps formed by the chemical reaction of the constituent fatty acid molecules and the rubbing surfaces. The biodegradable oils show superior lubricant performance compared to the paraffin-based mineral oil, despite their poor oxidation stability. Oxidation induction and thermo-gravimetric characteristics of the biodegradable oils are closely related to their polyunsaturated and monounsaturated fatty acid composition. <B>Originality/value</B> - The paper shows how these biodegradable oils could be used as good substitute for petroleum mineral oils in as-received state or little antioxidant additives.