Characteristics of a-GaN films and a-AlGaN/GaN heterojunctions prepared on r-sapphire by two-stage growth process

Polyakov, A. Y.,Jang, Lee-Woon,Smirnov, N. B.,Govorkov, A. V.,Kozhukhova, E. A.,Yugova, T. G.,Reznik, V. Y.,Pearton, S. J.,Baik, Kwang Hyeon,Hwang, Sung-Min,Jung, Sukkoo,Lee, In-Hwan American Institute of Physics 2011 JOURNAL OF APPLIED PHYSICS - Vol.110 No.9

<P>The electrical properties, presence of deep electron and hole traps and photoluminescence spectra were measured for undoped a-GaN films grown by metal-organic chemical vapor deposition (MOCVD) in a two-stage process using a high V/III ratio at the first stage and low V/III ratio at the second stage. Growth was performed on r-sapphire substrates with a high temperature GaN nucleation layer. The films showed a full width at half maximum of 450-470 arcseconds for the (11-20) x-ray rocking curve with little anisotropy with respect to the sample rotation around the growth direction. The stacking fault (SF) density determined by selective etching was similar to 5 x 10(4) cm(-1). The residual donor concentration was 10(14)-10(15) cm(-3), with a very low density (2.5 x 10(13) cm(-3)) of electron traps located at E-c - 0.6 eV, which are believed to be one of the major non-radiative recombination centers in nonpolar GaN. Consequently, the films showed a high intensity of bandedge luminescence with negligible contribution from defect bands associated with SFs. In contrast to previously studied nonpolar GaN films, the a-GaN layers showed a high concentration of gallium-vacancy-related acceptors near E-v + 1 eV and a strong yellow luminescence band, both indicating that growth conditions were effectively N-rich. a-AlGaN/GaN heterojunctions with thin heavily Si doped AlGaN barriers made on a-GaN substrates showed two-dimensional electron gas (2DEG) concentrations of 1.2 x 10(13) cm(-3), with 2DEG mobility of 80 cm(2)/Vs. Capacitance-voltage profiling of Schottky diodes on these HJs suggest that the 2DEG is fully depleted by the built-in voltage of the Schottky diode. (C)2011 American Institute of Physics. [doi: 10.1063/1.3658026]</P>

THE UNAM-KIAS CATALOG OF ISOLATED GALAXIES

Herná,ndez-Toledo, H. M.,Vá,zquez-Mata, J. A.,Martí,nez-Vá,zquez, L. A.,Choi, Yun-Young,Park, Changbom American Institute of Physics 2010 The Astronomical journal Vol.139 No.6

<P>A new catalog of isolated galaxies from the Sloan Digital Sky Survey Data Release 5 (SDSS DR5) is presented. A total of 1520 isolated galaxies were found in 1.4 sr of sky. The selection criteria in this UNAM-KIAS catalog are a variation on the criteria developed by Karachentseva, including full redshift information. Through an image processing pipeline that takes advantage of the high-resolution (~0<img entity='farcs' SRC='http://ej.iop.org/icons/Entities/farcs.gif' ALT='farcs' ALIGN='BOTTOM' />4 pixel<SUP>–1</SUP>) and high dynamic range of the SDSS images, a uniform g-band morphological classification for all these galaxies is presented. We identify 80% (Sa-Sm) spirals (50% later than Sbc types) on one hand, and a scarce population of early-type E (6.5%) and S0 (8%) galaxies amounting to 14.5% on the other hand. This magnitude-limited catalog is ~80% complete at 16.5, 15.6, 15.2, 14.6, and 14.4 mag in the ugriz bands, respectively. Some representative physical properties including SDSS magnitudes and color distributions, color-color diagrams, absolute magnitude-color, and concentration-color diagrams as a function of morphological type are presented. The UNAM-KIAS Morphological Atlas is also released along with this paper. For each galaxy of a type later than Sa, a mosaic is presented that includes (1) a g-band logarithmic image, (2) a g-band filtered-enhanced image where a Gaussian kernel of various sizes was applied, and (3) a red giant branch color image from the SDSS database. For E/S0/Sa galaxies, in addition to the images in (1), (2), and (3), plots of r-band surface brightness and geometric profiles (ellipticity ε, position angle PA, and A<SUB>4</SUB>/B<SUB>4</SUB> coefficients of the Fourier series expansions of deviations of a pure ellipse) are provided. The size of the sample, the redshift completeness, the availability of high-quality multicolor photometric data and detailed morphological and spectroscopic information make the UNAM-KIAS catalog of isolated galaxies a suitable sample to address important issues such as (1) comparative studies of environmental effects, (2) constraining the currently competing scenarios of galaxy formation and evolution, (3) the nature and evolution of elliptical and spiral galaxies in the field, (4) the spectral properties of a statistically significant number of isolated galaxies and their evolution as a function of redshift, and (5) the fraction of active galactic nuclei in isolated environments, among other important topics. The optimization and estimation of new structural parameters as well as important information to complement existing ones in other wavelengths is being carried out.</P>

Search for a very light NMSSM Higgs boson produced in decays of the 125 GeV scalar boson and decaying into τ leptons in pp collisions at s = 8 $$ \sqrt{s}=8 $$ TeV

Khachatryan, V.,Sirunyan, A. M.,Tumasyan, A.,Adam, W.,Asilar, E.,Bergauer, T.,Brandstetter, J.,Brondolin, E.,Dragicevic, M.,Erö,, J.,Flechl, M.,Friedl, M.,Frü,hwirth, R.,Ghete, V. M.,Hartl, C. Springer-Verlag 2016 Journal of high energy physics Vol.2016 No.1

<P>A search for a very light Higgs boson decaying into a pair of tau leptons is presented within the framework of the next-to-minimal supersymmetric standard model. This search is based on a data set corresponding to an integrated luminosity of 19.7 fb(-1) of proton-proton collisions collected by the CMS experiment at a centre-of-mass energy of 8 TeV. The signal is defined by the production of either of the two lightest scalars, h(1) or h(2), via gluon-gluon fusion and subsequent decay into a pair of the lightest Higgs bosons, a(1) or h(1). The h(1) or h(2) boson is identified with the observed state at a mass of 125 GeV. The analysis searches for decays of the a(1) (h(1)) states into pairs of tau leptons and covers a mass range for the a(1) (h(1)) boson of 4 to 8 GeV. The search reveals no significant excess in data above standard model background expectations, and an upper limit is set on the signal production cross section times branching fraction as a function of the a(1) (h(1)) boson mass. The 95% confidence level limit ranges from 4.5 pb at m(a1) (m(h1)) = 8 GeV to 10.3 pb at m(a1) (m(h1)) = 5 GeV.</P>

Design a steam chamber to avoid over gelatinization thus producing straight and single form of rice noodles strings

M.K.A. Shanika(M.K.A. Shanika ),K.S. Kumararathna(K.S. Kumararathna ),S.B. Navarathne(S.B. Navarathne ),V.S. Jayamanne(V.S. Jayamanne ) 한국축산식품학회 2022 Food and Life Vol.2022 No.3

Over gelatinization of extruded rice noodles during open wet steam cooking is a major problem in the food processing industry and occurs due to the condensation of water droplets that come into contact with noodle strings during the steaming process. This issue may arise due to the presence of stuck noodles in the finished product. Therefore, 5 prototype designs; wooden frame enclosed with polythene sheet (A), wooden frame enclosed with gray cloth (B), wooden frame enclosed with a plywood sheet with two steam inlets in the galvanized door (C), wooden frame enclosed with plywood sheet with multiple steam inlets in the galvanized door (D), and completely enclosed galvanized chamber were made (E). All steam chambers had multiple steam inlets in lateral walls except the chamber with gray cloth. Red rice noodles were prepared from the combination (16% w/w moisture, 200 μm, water at ambient temperature (30±2℃), control atmosphere, 20 min) and fed into five different types of prototype designs to complete the cooking (gelatinization) process. The performance of the five prototype designs was evaluated in terms of the percentage of dried noodles coming out of each design in a single straight form. According to the results, the percentage of dried noodles coming out of each design was (A-50.0±7.1%, B-15.0±5.0%, C-15.0±5.0%, D-50.0±7.1%, E-77.5±4.3% w/w) analyzed. The mean values of all designs revealed that the effective prototype design was “design E” (steam chamber consisted of a completely enclosed galvanized chamber with multiple steam inlets in the two lateral sides). It was able to produce a higher percentage of straight single noodles when compared to other designs. In conclusion, design E is the effective steam chamber to produce straight single rice noodles for the market. The design of a steam chamber is also a very important aspect to avoid over gelatinization thus producing straight and single form of rice noodles strings.

2G HTS wire with enhanced engineering current density attained through the deposition of HTS layer with increased thickness

Markelov, A.,Valikov, A.,Chepikov, V.,Petrzhik, A.,Massalimov, B.,Degtyarenko, P.,Uzkih, R.,Soldatenko, A.,Molodyk, A.,Sim, Kideok,Hwang, Soon The Korea Institute of Applied Superconductivity a 2019 한국초전도저온공학회논문지 Vol.21 No.4

2G HTS wire with high engineering current density is desired for applications where compact, high power density superconducting equipment is important. We have succeeded in enhancing engineering current density of commercial SuperOx 2G HTS wire based on GdBCO by increasing the HTS layer thickness without fast degradation of the HTS film microstructure. This was possible after improving the temperature uniformity along the HTS film deposition zone. In particular, the wire engineering current density was increased from 700-770 A/㎟ (for a 65 ㎛-thick wire without stabilisation) or 430-480 A/㎟ (for a 105 ㎛-thick stabilised wire) at the beginning of this study to almost 1200 A/㎟ (for a 67 ㎛-thick wire without stabilisation) or 770 A/㎟ (for a 107 ㎛-thick stabilised wire) at completion of this study.

Differential effects of triterpene glycosides, frondoside A and cucumarioside A₂-2 isolated from sea cucumbers on caspase activation and apoptosis of human leukemia cells

Jin, J.O.,Shastina, V.V.,Shin, S.W.,Xu, Q.,Park, J.I.,Rasskazov, V.A.,Avilov, S.A.,Fedorov, S.N.,Stonik, V.A.,Kwak, J.Y. North-Holland Pub ; Elsevier Science Ltd 2009 FEBS letters Vol.583 No.4

Frondoside A is a pentaoside having an acetyl moiety at the aglycon ring and xylose as a third monosaccharide residue. Cucumarioside A<SUB>2</SUB>-2 is a pentaoside having glucose as a third monosaccahride unit. We compared the effects of frondoside A and A<SUB>2</SUB>-2 for cell death-inducing capability with close attention paid to structure-activity relationships. Both frondoside A and A<SUB>2</SUB>-2 strongly induced apoptosis of leukemic cells. Frondoside A-induced apoptosis was more potent and rapid than A<SUB>2</SUB>-2-induced apoptosis. A<SUB>2</SUB>-2-induced but not frondoside A-induced apoptosis was caspase-dependent. This suggests that holothurians may induce apoptosis of leukemic cells caspase-dependently or -independently, depending on the holothurian structure.

Electrical properties and deep traps spectra of a-plane GaN films grown on r-plane sapphire

Polyakov, A.Y.,Smirnov, N.B.,Govorkov, A.V.,Markov, A.V.,Sun, Q.,Zhang, Y.,Yerino, C.D.,Ko, T.S.,Lee, I.H.,Han, J. Elsevier 2010 Materials science & engineering. B, Advanced funct Vol.166 No.3

Electrical properties, deep traps spectra and luminescence spectra were studied for two undoped a-plane GaN (a-GaN) films grown on r-plane sapphire using metalorganic chemical vapor deposition and differing by structural perfection. For sample A, the a-GaN film was directly deposited on AlN buffer. A two-step growth scheme was implemented for sample B, including an initial islanding growth stage and a subsequent enhanced lateral growth. Preliminary detailed X-ray analysis showed that the stacking faults density was 8x10<SUP>5</SUP>cm<SUP>-1</SUP> for sample A and 1.7x10<SUP>5</SUP>cm<SUP>-1</SUP> for sample B. Electrical properties of a-GaN films were largely determined by deep traps with a level near E<SUB>c</SUB> -0.6eV, with other prominent traps having the activation energy of 0.25eV. The Fermi level was pinned by the E<SUB>c</SUB> -0.6eV deep traps for sample A, but shifted to the vicinity of the shallower 0.25eV traps for sample B, most likely due to the reduced density of the 0.6eV traps. This decrease of deep traps density is accompanied by a very pronounced improvement in the overall luminescence intensity. A correlation of the observed improvement in deep traps spectra and luminescence efficiency with the improved crystalline quality of the films is discussed.

Fast response of sprayed vanadium pentoxide (V₂O₅) nanorods towards nitrogen dioxide (NO₂) gas detection

Mane, A.A.,Suryawanshi, M.P.,Kim, J.H.,Moholkar, A.V. Elsevier BV * North-Holland 2017 Applied Surface Science Vol.403 No.-

<P><B>Abstract</B></P> <P>The V<SUB>2</SUB>O<SUB>5</SUB> nanorods have been successfully spray deposited at optimized substrate temperature of 400°C onto the glass substrates using vanadium trichloride (VCl<SUB>3</SUB>) solution of different concentrations. The effect of solution concentration on the physicochemical and NO<SUB>2</SUB> gas sensing properties of sprayed V<SUB>2</SUB>O<SUB>5</SUB> nanorods is studied at different operating temperatures and gas concentrations. The XRD study reveals the formation of V<SUB>2</SUB>O<SUB>5</SUB> having an orthorhombic symmetry. The FE-SEM micrographs show the nanorods-like morphology of V<SUB>2</SUB>O<SUB>5</SUB>. The AFM micrographs exhibit a well covered granular surface topography. For direct allowed transition, the band gap energy values are found to be decreased from 2.45eV to 2.42eV. The nanorods deposited with 30mM solution concentration shows the maximum response of 24.2% for 100ppm NO<SUB>2</SUB> gas concentration at an operating temperature of 200°C with response and recovery times of 13s and 140s, respectively. Finally, the chemisorption mechanism of NO<SUB>2</SUB> gas on the V<SUB>2</SUB>O<SUB>5</SUB> nanorods is discussed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Effect of solution concentration on physicochemical properties of sprayed V<SUB>2</SUB>O<SUB>5</SUB> nanorods is studied. </LI> <LI> Good re­sponse and short re­sponse- re­covery times of V<SUB>2</SUB>O<SUB>5</SUB> nanorods towards NO<SUB>2</SUB> gas show it is potential material for fab­ri­ca­tion of NO<SUB>2</SUB> sensor. </LI> <LI> The chemisorption mechanism of NO<SUB>2</SUB> gas on the V<SUB>2</SUB>O<SUB>5</SUB> nanorods is discussed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Species-specific PCR-based marker for rapid detection of Aspidiotus rigidus Reyne (Hemiptera: Diaspididae)

Latina Romnick A.,Lantican Darlon V.,Guerrero Michelle S.,Rubico Edsel C.,Laquinta Janice F.,Caoili Barbara L. 한국응용곤충학회 2022 Journal of Asia-Pacific Entomology Vol.25 No.1

The Philippine coconut production has been greatly affected by the recent devastating infestation of Aspidiotus spp. However, identification of the outbreak species, Aspidotus rigidus, has been a challenge using morphological approaches. Molecular identification via PCR sequencing of insect barcoding genes has been implemented, but the overall process is time-consuming and costly. Thus, we developed and optimized a species-specific PCR-based molecular marker for rapid, efficient and cost-effective molecular identification of A. rigidus. The molecular marker was designed based on the sequences of the partial 28S ribosomal RNA gene from species of Aspidiotus that feed on coconut in the Philippines, A. rigidus, A. destructor and A. excisus. Multiple alignment of nucleotide se quences revealed a conserved 16-bp insertion-deletion (InDel) site common to all A. rigidus specimens identified from which the A. rigidus-specific oligonucleotide (RIG1) primer targeting an approximately 570 bp fragment size was designed. Results showed that the species-specific DNA marker technology consistently delineated laboratory-reared and field-collected A. rigidus samples from A. destructor and A. excisus. The protocol offers a rapid and reliable method for the early detection of A. rigidus infestation in high-risk areas planted with coconut in the country.

Molecular basis involved in the blocking effect of antidepressant metergoline on C-type inactivation of Kv1.4 channel

Bai, Hyoung-Woo,Eom, Sanung,Yeom, Hye Duck,Nguyen, Khoa V.A.,Lee, Jaeeun,Sohn, Sung-Oh,Lee, Jun-Ho Elsevier 2019 NEUROPHARMACOLOGY - Vol.146 No.-

<P><B>Abstract</B></P> <P>Voltage-gated potassium channels (VGKCs) are transmembrane ion channels specific for potassium. Currently there are nine kinds of VGKCs. Kv1.4 is one of shaker-related potassium channels. It is a representative alpha subunit of potassium channels that can inactivate A type-currents, leading to N pattern inactivation. Inactivation of Kv channels plays an important role in shaping electrical signaling properties of neuronal and muscular cells. The shape of N pattern inactivation can be modified by removing the N-terminal (NT) domain which results in non-inactivated currents and C pattern inactivation. In a previous work, we have reported the regulatory effect of metergoline on Kv1.4 and Nav1.2 channel activity. In the present study, we constructed a mutant of deleted 61 residues from NT of Kv1.4 channels (Kv1.4 Δ2-61) and found that it induced an outward peak and steady-state currents We also studied the modulation effect of metergoline on the activity of this Kv1.4 Δ2-61 mutant channel without having the N-terminal quick inactivation domain. Our results revealed that treatment with metergoline inhibited NT deleted Kv1.4 mutant channel activity in a concentration-dependent manner which was reversible. Interestingly, metergoline treatment induced little effects on the outward peak current in the deleted Kv1.4 mutant channel. However, metergoline treatment conspicuously inhibited steady state currents of Kv1.4 Δ2-61 channels with acceleration current mode. The acceleration of steady-state current of deleted Kv1.4 mutant channel occurred in a concentration-dependent manner. This means that metergoline can accelerate C pattern inactivation of Kv1.4 Δ2-61 channel by acting as an open state dependent channel blocker. We also performed site-directed mutations in V561A and K532Y, also known as C-type inactivation sites. V561A, K532Y, and V561A + K532Y substitution mutants significantly attenuated the acceleration effect of metergoline on C pattern inactivation of hKv1.4 channel currents. In docking modeling study, predicted binding residues for metergoline were analyzed for six amino acids. Among them, the K532 residue known as the C-type inactivation site was analyzed to be a major site of action. Then various mutants were constructed. K532 substitution mutant significantly abolished the effect of metergoline on Kv1.4 currents among various mutants whereas other changes had slight inhibitory effects. Furthermore, we found that metergoline had specificity for Kv1.4, but not for Kv1.5 currents. In addition, the A type current in rat neuronal cell was inhibited and accelerated of inactivation. This result further shows that metergoline might interact with Lys532 residue and then accelerate C pattern inactivation of Kv1.4 channels with channel type specificity. Taken together, these results demonstrate the molecular basis involved in the effect of metergoline, an ergot alkaloid, on human Kv1.4 channel, providing a novel interaction ligand.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Metergoline, ergot-derived psychoactive drug, produced inhibition on steady state current of Kv1.4 channel currents. </LI> <LI> Treatment of metergoline on Kv1.4 Δ2-61 channel currents produced significant inhibitions of the non-inactivating plateau than peak currents. </LI> <LI> Metergoline interacted predominantly with residues at channel pore region of Kv1.4 channel. </LI> <LI> Metergoline is more selective for Kv1.4 channels and is shown the effects as open channel blocker. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>