• Title/Summary/Keyword: barrier function

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Photoluminescence Studies of InP/InGaP Quantum Structures Grown by a Migration Enhanced Molecular Beam Epitaxy

  • Cho, Il-Wook;Ryu, Mee-Yi;Song, Jin Dong
    • Applied Science and Convergence Technology
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    • v.25 no.4
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    • pp.81-84
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    • 2016
  • InP/InGaP quantum structures (QSs) grown on GaAs substrates by a migration-enhanced molecular beam epitaxy method were studied as a function of growth temperature (T) using photoluminescence (PL) and emission-wavelength-dependent time-resolved PL (TRPL). The growth T were varied from $440^{\circ}C$ to $520^{\circ}C$ for the formation of InP/InGaP QSs. As growth T increases from $440^{\circ}C$ to $520^{\circ}C$, the PL peak position is blue-shifted, the PL intensity increases except for the sample grown at $520^{\circ}C$, and the PL decay becomes fast at 10 K. Emission-wavelength-dependent TRPL results of all QS samples show that the decay times at 10 K are slightly changed, exhibiting the longest time around at the PL peak, while at high T, the decay times increase rapidly with increasing wavelength, indicating carrier relaxation from smaller QSs to larger QSs via wetting layer/barrier. InP/InGaP QS sample grown at $460^{\circ}C$ shows the strongest PL intensity at 300 K and the longest decay time at 10 K, signifying the optimum growth T of $460^{\circ}C$.

HVEM is a TNF Receptor with Multiple Regulatory Roles in the Mucosal Immune System

  • Shui, Jr-Wen;Kronenberg, Mitchell
    • IMMUNE NETWORK
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    • v.14 no.2
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    • pp.67-72
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    • 2014
  • The herpes virus entry mediator (HVEM) is a member of the tumor necrosis factor receptor superfamily (TNFRSF), and therefore it is also known as TNFRSF14 or CD270 (1,2). In recent years, we have focused on understanding HVEM function in the mucosa of the intestine, particularly on the role of HVEM in colitis pathogenesis, host defense and regulation of the microbiota (2-4). HVEM is an unusual TNF receptor because of its high expression levels in the gut epithelium, its capacity to bind ligands that are not members of the TNF super family, including immunoglobulin (Ig) superfamily members BTLA and CD160, and its bi-directional functionality, acting as a signaling receptor or as a ligand for the receptor BTLA. Clinically, Hvem recently was reported as an inflammatory bowel disease (IBD) risk gene as a result of genome wide association studies (5,6). This suggests HVEM could have a regulatory role influencing the regulation of epithelial barrier, host defense and the microbiota. Consistent with this, using mouse models, we have revealed how HVEM is involved in colitis pathogenesis, mucosal host defense and epithelial immunity (3,7). Although further studies are needed, our results provide the fundamental basis for understanding why Hvem is an IBD risk gene, and they confirm that HVEM is a mucosal gatekeeper with multiple regulatory functions in the mucosa.

Enhanced Hole Injections in Organic Light Emitting Diode using Rhodium Oxide Coated Anode

  • Kim, Soo-Young;Choi, Ho-Won;Kim, Kwang-Young;Tak, Yoon-Heung;Lee, Jong-Lam
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.5 no.2
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    • pp.77-82
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    • 2005
  • We compare electrical and optical properties of organic light emitting diodes (OLEDs) using rhodium-oxide-coated indium-tin-oxide ($O_2$-Rh/ITO) to that using $O_2$-plasma-treated ITO (ITO) anodes. The turn-on voltage decreased from 7 V to 5 V and luminance value increased when the $O_2$ plasma treated Rh layer was deposited on ITO. Synchrotron radiation photoelectron spectroscopy results showed the dipole energies of both ITO and $O_2$-Rh/ITO were same with each other, - 0.3 eV, meaning the formation of same amount of interface dipole. The secondary electron emission spectra revealed that the work function of $O_2$-Rh/ITO is higher hy 0.2 eV than that of ITO, resulting in the decrease of the tum-on voltage via reduction ofhole injection barrier.

Axial compressive behaviour of circular CFFT: Experimental database and design-oriented model

  • Khan, Qasim S.;Sheikh, M. Neaz;Hadi, Muhammad N.S.
    • Steel and Composite Structures
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    • v.21 no.4
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    • pp.921-947
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    • 2016
  • Concrete Filled Fibre Reinforced Polymer Tube (CFFT) for new columns construction has attracted significant research attention in recent years. The CFFT acts as a formwork for new columns and a barrier to corrosion accelerating agents. It significantly increases both the strength capacity (Strength enhancement ratio) and the ductility (Strain enhancement ratio) of reinforced concrete columns. In this study, based on predefined selection criteria, experimental investigation results of 134 circular CFFT columns under axial compression have been compiled and analysed from 599 CFFT specimens available in the literature. It has been observed that actual confinement ratio (expressed as a function of material properties of fibres, diameter of CFFT and compressive strength of concrete) has significant influence on the strength and ductility of circular CFFT columns. Design oriented models have been proposed to compute the strength and strain enhancement ratios of circular CFFT columns. The proposed strength and strain enhancement ratio models have significantly reduced Average Absolute Error (AAE), Mean Square Error (MSE), Relative Standard Error of Estimate (RSEE) and Standard Deviation (SD) as compared to other available strength and strain enhancement ratios of circular CFFT column models. The predictions of the proposed strength and strain enhancement ratio models match well with the experimental strength and strain enhancement ratios investigation results in the compiled database.

Classification, Structure, and Bioactive Functions of Oligosaccharides in Milk

  • Mijan, Mohammad Al;Lee, Yun-Kyung;Kwak, Hae-Soo
    • Food Science of Animal Resources
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    • v.31 no.5
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    • pp.631-640
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    • 2011
  • Milk oligosaccharides are the complex mixture of six monosaccharides namely, D-glucose, D-galactose, N-acetyl-glucosamine, N-acetyl-galactosamine, L-fucose, and N-acetyl-neuraminic acid. The mixture is categorized as neutral and acidic classes. Previously, 25 oligosaccharides in bovine milk and 115 oligosaccharides in human milk have been characterized. Because human intestine lacks the enzyme to hydrolyze the oligosaccharide structures, these substances can reach the colon without degradation and are known to have many health beneficial functions. It has been shown that this fraction of carbohydrate can increase the bifidobacterial population in the intestine and colon, resulting in a significant reduction of pathogenic bacteria. The role of milk oligosaccharides as a barrier against pathogens binding to the cell surface has recently been demonstrated. Milk oligosaccharides have the potential to produce immuno-modulation effects. It is also well known that oligosaccharides in milk have a significant influence on intestinal mineral absorption and in the formation of the brain and central nervous system. Due to its structural resemblance, bovine milk is considered to be the most potential source of oligosaccharides to produce the same effect of oligosaccharides present in human milk. This review describes the characteristics and potential health benefits of milk oligosaccharides as well as the prospects of oligosaccharides in bovine milk for use in functional foods.

Compressibility and hydraulic conductivity of calcium bentonite treated with pH-responsive polymer

  • Choo, Hyunwook;Choi, Youngmin;Kim, Young-Uk;Lee, Woojin;Lee, Changho
    • Geomechanics and Engineering
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    • v.22 no.4
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    • pp.329-337
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    • 2020
  • Polyacrylamide (PAM) possesses high water absorption capacity and a unique pH-dependent behavior that confer large potential to enhance the engineering performance of clays. In this study, calcium bentonite was treated with a nonionic PAM. Flexible-wall permeability test and the consolidation test were performed at different pH values to evaluate the effects of PAM treatment on the hydraulic and consolidation properties. Test results demonstrate that index properties are affected by the adsorbed PAM on clay surface: a decrease in specific gravity, a decrease in net zeta potential, and an increase in liquid limit are observed due to the PAM treatment. At a given pH, the compressibility of the treated clay is greater than that of the untreated clay. However, the compression indices of untreated and treated clays can be expressed as a single function of the initial void ratio, regardless of pH. Hydraulic conductivity is reduced by PAM treatment about 5 times at both neutral and alkaline pH conditions under similar void ratios, because of the reduction in size of the water flow channel by PAM expansion. However, at acidic pH, the hydraulic conductivity of the treated clay is slightly higher than the untreated clay. This reflects that the treated bentonite with PAM can be beneficially used in barrier system for highly alkaline residues.

Temperature-dependent Luminescence Properties of Digital-alloy In(Ga1-zAlz)As

  • Cho, Il-Wook;Ryu, Mee-Yi;Song, Jin Dong
    • Applied Science and Convergence Technology
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    • v.27 no.3
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    • pp.56-60
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    • 2018
  • The optical properties of the digital-alloy $(In_{0.53}Ga_{0.47}As)_{1-z}/(In_{0.52}Al_{0.48}As)_z$ grown by molecular beam epitaxy as a function of composition z (z = 0.4, 0.6, and 0.8) have been studied using temperature-dependent photoluminescence (PL) and time-resolved PL (TRPL) spectroscopy. As the composition z increases from 0.4 to 0.8, the PL peak energy of the digital-alloy $In(Ga_{1-z}Al_z)As$ is blueshifted, which is explained by the enhanced quantization energy due to the reduced well width. The decrease in the PL intensity and the broaden FWHM with increasing z are interpreted as being due to the increased Al contents in the digital-alloy $In(Ga_{1-z}Al_z)As$ because of the intermixing of Ga and Al in interface of InGaAs well and InAlAs barrier. The PL decay time at 10 K decreases with increasing z, which can be explained by the easier carrier escape from InGaAs wells due to the enhanced quantized energies because of the decreased InGaAs well width as z increases. The emission energy and luminescence properties of the digitalalloy $(InGaAs)_{1-z}/(InAlAs)_z$ can be controlled by adjusting composition z.

The measurement of three-dimensional temporal behavior according to the pressure in the plasma display panel (플라즈마 디스플레이 패널의 압력별 3차원 시간 분해 측정)

  • Kim, Son-Ic;Choi, Hoon-Young;Lee, Seok-Hyun;Lee, Seung-Gol
    • Proceedings of the KIEE Conference
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    • 2002.07c
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    • pp.1628-1630
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    • 2002
  • In this paper, we measured 3-dimensional temporal behavior of the light emitted from discharge cell of plasma display panel(PDP) as a function of the pressure using the scanned point detecting system. The detected light signal through the PM tube is sent on the oscilloscope and oscilloscope which is connected to PC with GPIB. The whole system is controlled by a PC. From the temporal behavior results, we could analyze the discharge behavior of panel with Ne-Xe(4%) mixing gas and 300torr, 400torr, 500torr pressure. The top view of panel shows that the discharge moves from inner edge of cathode electrode to outer cathode electrode forming arc type. At the 300torr, initial emission time is very fast. The side view of panel shows that the light is detected up to $150{\mu}m$ height of barrier rib. In the panel of 300torr, emission distribution is wider than the others.

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Effects of Commercial Topical Shampoos on Skin Surface Sebum in Normal Canine Skin (개에서 피부 치료용 샴푸가 표피유분에 미치는 영향)

  • Hwang, Cheol-Yong;Oh, Tne-Ho
    • Journal of Veterinary Clinics
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    • v.19 no.2
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    • pp.225-227
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    • 2002
  • Various commercial shampoos were frequently prescribed for dermatologicstherapy in small animal practice. Skin surface sebum affected by the shampoos, however, was not evaluated routinely. In order to evaluate the skin surface sebum for the exact prescription of shampoos methods to measure skin surface sebum of shampoos are needed. This study was undertaken to evaluate the skin surface sebum effect of shampoo on canine skin using sebometry. Five healthy dogs were applied with 3 commercial shampoos: Sebocalm, Sebolytics, and Benzoyl peroxide. Sebocalm had a great effect on skin surface seoum and normal saline also affected the skin sebum. Sebolytics and benzoyl peroxide had a moderate effect of skin sebum. The lowest effect was shown in detergent. Therefore, Sebumeter was considered a good and convenient apparatus for skin sebum measurement in order to evaluate the effect of shampoos on skin sebum. None of the products tested had any negative effect on the skin barrier function.

Investigation of detection wavelength of Quantum Well Infrared-Photodetector

  • Hwang, S.H.;Lim, J.G.;Song, J.D.;Shin, J.C.;Heo, D.C.;Choi, W.J.
    • Applied Science and Convergence Technology
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    • v.24 no.6
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    • pp.257-261
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    • 2015
  • We report on GaAs/AlGaAs quantum well infrared photodetectors (QWIPs) that can cover the spectral range of $3.6-25{\mu}m$. One advantage of the GaAs QWIPs is the wavelength tenability as a function of their structural parameters. We have performed a systematic calculation on the detection wavelength of a typical $GaAs/Al_xGa_{1-x}As$ multi-quantum-well photodetector, with the aluminum mole fraction (x) of $Al_xGa_{1-x}As$ barrier in the range of 0.15-0.43 and the quantum-well width range from 30 to 60 $60{\AA}$. Design and fabrication of a QWIP based on $GaAs/Al_{0.23}Ga_{0.77}As$ structure with $37{\AA}$-thick well width has been carried out. The calculated operation wavelength of the QWIP is in a good agreement with the experimental data taken by photo response and activation energy calculation from thermal quenching of integrated photoluminescence.