Won-Jong Lee

One of the effective strategies to enhance the photovoltaic performance of polymer solar cells (PSCs) is to synthesize random copolymers composed of one electron donating unit and two different electron accepting units, if the absorptions of two electron accepting units are complementary to each other. To this end, we synthesized a new series of conjugated random copolymer composed of bithiophene (electron donating unit) with thiophene-capped diketopyrrolopyrrole (TDPP) and pyridine-capped diket

While there is an urgent need for semiconductor-based efficient deep ultraviolet (DUV) sources, the efficiency of AlGaN DUV light-emitting diodes (LEDs) remains very low because the extraction of DUV photons is significantly limited by intrinsic material properties of AlGaN. Here, we present an elegant approach based on a DUV LED having multiple mesa stripes whose inclined sidewalls are covered by a MgF2/Al omni-directional mirror to take advantage of the strongly anisotropic transverse-magnetic

Despite a rapidly growing demand for efficient man-made deep-ultraviolet (DUV) light sources, widespread adoption of AlGaN-based DUV light-emitting diodes (LEDs) is currently obstructed by extremely poor extraction of DUV photons due to the intrinsic material properties of the AlGaN active region. Here, we present 280 nm AlGaN DUV LEDs having arrays of truncated cone (TC)-shaped active mesas coated with MgF 2 /Al reflectors on the inclined sidewalls of the cone to effectively extract the intrins

We present a remarkable improvement in the efficiency of AlGaN deep-ultraviolet light-emitting diodes (LEDs) enabled by the coupling of localized surface plasmon resonance (LSPR) mediated by a high-density array of Al nanoparticles (NPs). The Al NPs with an average diameter of ∼40 nm were uniformly distributed near the Al0.43Ga0.57N/Al0.50Ga0.50N multiple quantum well active region for coupling 285 nm emission by block copolymer lithography. The internal quantum efficiency is enhanced by 57.7% b

Ternary blends composed of two donor absorbers with complementary absorptions provide an opportunity to enhance the short-circuit current and thus the power conversion efficiency (PCE) of organic solar cells. In addition to complementary absorption of two donors, ternary blends may exhibit favorable morphology for high-performance solar cells when one chooses properly the donor pair. For this purpose, we develop a ternary blend with two donors (diketopyrrolopyrrole-based polymer (PTDPP2T) and sm

<bold>PBCDTBT</bold>and<bold>PBCDPP2T</bold>are synthesized by introducing an oxygen atom in the fluorene unit in<bold>PFDTBT</bold>and<bold>PFDPP2T</bold>, respectively.<bold>PBCDTBT</bold>- and<bold>PBCDPP2T</bold>-based devices exhibit higher<italic>J</italic>_SCs than<bold>PFDTBT</bold>and<bold>PFDPP2T</bold>-based devices, respectively.

Abstract The silkworm hemolymph has an anti-apoptotic activity in insect, mammalian, and human cell systems. The protein from silkworm hemolymph with the highest apoptosis inhibiting activity was found to be 30Kc19 protein, which was one of the ‘30K proteins’. In this study, 30Kc19 protein encoded by the PMhÅNV gene of the silkworm was expressed Escherichia coli with (pET-22b(+)) and without (pET-3a) pelB leader sequence. 30Kc19 protein was over-expressed largely as a soluble form by pET-3a and

By analyzing the causes of precipitation and clogging in continuous flow dichlorocyclopropanation, we established that the flow reaction can be performed only with T‐junctions and microtubes. Unlike tertiary amines, when quaternary ammonium salts were used as PTCs, precipitation and clogging in microchannels did not occur, and an excellent yield of up to 99% was obtained after optimizing the reaction temperature, reactant concentration, and retention time. In the scale‐up experiment, the reactio

The characteristics of organic thin-films transistors (OTFTs) with the anodized aluminum oxide insulator have been investigated. The OTFT with the barrier-type aluminum oxide insulator exhibited the mobility of 0.09 cm2/Vs, the subthreshold slope of 1.3 V/decade, the threshold voltage of −2.2 V, and the on/off ratio of 7.7 × 104, which are superior to those for the device with the porous-type insulator. The smooth surface of the barrier-type film is found to contribute to a long range hopping of

The article is a review of different pathogenetic mechanisms (infectious, NSAID-associated, stress-dependent and those stipulated by microcirculation disturbances in the gastroduodenal zone) of stomach and duodenum ulcers in patients with scheduled surgical intervention on the heart with the use of cardiopulmonary bypass. Some vexed questions related to treatment tactics of peptic ulcers in these patients are discussed.