Optical spectroscopy of PPV-based block copolymers of nanostructured supramolecular organic semiconductor.

Yang, Q,Battle, R,Zhang, C,Ma, S M,Seo, J T,Tabibi, B,Temple, D,Sun, S,Jung, S S,Namkung, M American Scientific Publishers 2009 Journal of nanoscience and nanotechnology Vol.9 No.2

<P>The third-order nonlinearity of a PPV-based nanostructured supramolecular organic semiconductor (DBAB), with an electron donor (D) connected to an electron acceptor (A) via nonconjugated and flexible bridge (B) units, was investigated in this work at both near-resonant (532 nm) and nonresonant (1064 nm) wavelength by using degenerate four-wave mixing. The second hyperpolarizabilities of D, A, and DBAB at 532 nm were found to be approximately 2.42 x 10(-43) m2/V2, 7.75 x 10(-44) m2/V2, and 1.80 x 10(-43) m2/V2 in copolarization geometry, and approximately 1.59 x 10(-43) m2/V2, 2.59 x 10(-44) m2/V2, and 1.18 x 10(-43) m2/V2 in orthogonal polarization geometry, respectively. The second hyperpolarizabilities of DBAB at 1064 nm were approximately 1.66 x 10(-46) m2/V2 and approximately 8.77 x 10(-47) m2/V2 for parallel and orthogonal polarization cases.</P>

Nonlinear optical properties of mushroom-shaped CdSe/CdS coreshells.

Ma, S M,Seo, J T,Yu, W,Yang, Q,Tabibi, B,Temple, D,Namkung, M,Heo, J,Kim, W J,Jung, S S American Scientific Publishers 2009 Journal of nanoscience and nanotechnology Vol.9 No.2

<P>The third-order nonlinear optical susceptibilities of mushroom-shaped CdSe/CdS coreshells as a function of concentration have been investigated using polarization- and concentration-resolved degenerate four-wave mixing in a resonant region. The effective third-order nonlinear optical susceptibilities, /chi(3)xxxx/ and /chi(3)xyyx/ of CdSe/CdS coreshells were estimated to be approximately 1.86 x 10(-21)-1.03 x 10(-20) m2/V2, and approximately 0.45 x 10(-21)-6.15 x 10(-21) m2/V2, respectively, for various concentrations of approximately 0.64 x 10(-3)-4.95 x 10(-3) mol/m3. The second hyperpolarizabilities, /<gammah>xxxx/ and /<gammah>xyyx/, of CdSe/CdS coreshells were extracted to be approximately 2.37 x 10(-41) m5/V2 and approximately 1.29 x 10(-41) m5/V2, respectively.</P>

Characteristics and composition of atmospheric aerosols in Phimai, central Thailand during BASE-ASIA

Li, C.,Tsay, S.C.,Hsu, N.C.,Kim, J.Y.,Howell, S.G.,Huebert, B.J.,Ji, Q.,Jeong, M.J.,Wang, S.H.,Hansell, R.A.,Bell, S.W. Pergamon Press ; Elsevier [distribution] 2013 Atmospheric environment Vol.78 No.-

Comprehensive measurements of atmospheric aerosols were made in Phimai, central Thailand (15.183<SUP>o</SUP>N, 102.565<SUP>o</SUP>E, elevation: 206 m) during the BASE-ASIA field experiment from late February to early May in 2006. The observed aerosol loading was sizable for this rural site (mean aerosol scattering: 108 +/- 64 Mm<SUP>-1</SUP>; absorption: 15 +/- 8 Mm<SUP>-1</SUP>; PM<SUB>10</SUB> concentration: 33 +/- 17 μg m<SUP>-3</SUP>), and dominated by submicron particles. Major aerosol compounds included carbonaceous (OC: 9.5 +/- 3.6 μg m<SUP>-3</SUP>; EC: 2.0 +/- 2.3 μg m<SUP>-3</SUP>) and secondary species (SO<SUB>4</SUB><SUP>2-</SUP>: 6.4 +/- 3.7 μg m<SUP>-3</SUP>, NH<SUB>4</SUB><SUP>+</SUP>: 2.2 +/- 1.3 μg m<SUP>-3</SUP>). While the site was seldom under the direct influence of large forest fires to its north, agricultural fires were ubiquitous during the experiment, as suggested by the substantial concentration of K<SUP>+</SUP> (0.56 +/- 0.33 μg m<SUP>-3</SUP>). Besides biomass burning, aerosols in Phimai during the experiment were also strongly influenced by industrial and vehicular emissions from the Bangkok metropolitan region and long-range transport from southern China. High humidity played an important role in determining the aerosol composition and properties in the region. Sulfate was primarily formed via aqueous phase reactions, and hygroscopic growth could enhance the aerosol light scattering by up to 60%, at the typical morning RH level of 85%. The aerosol single scattering albedo demonstrated distinct diurnal variation, ranging from 0.86 +/- 0.04 in the evening to 0.92 +/- 0.02 in the morning. This experiment marks the first time such comprehensive characterization of aerosols was made for rural central Thailand. Our results indicate that aerosol pollution has developed into a regional problem for northern Indochina, and may become more severe as the region's population and economy continue to grow.

CaMKIIα interacts with M4 muscarinic receptors to control receptor and psychomotor function

Guo, M. L.,Fibuch, E. E.,Liu, X. Y.,Choe, E. S.,Buch, S.,Mao, L. M.,Wang, J. Q. Nature Publishing Group 2010 The EMBO journal Vol.29 No.12

Formation of mesostructured titania thin films using isopropoxide precursors

G.Q.M. Lu,I. Kartini,P. Meredith,Diniz da Costa,J. D. Riches 한국물리학회 2004 Current Applied Physics Vol.4 No.2-4

Mesostructured titania thin lms were prepared by an evaporation-induced self-assembly process. The highly acidic sol pre-cursors contained titanium(IV) tetraisopropoxide (TTIP) as a titanium source, a tri-block copolymer Pluronic P123 as a template,and acetylacetonate and HCl as hydrolysis inhibitors. Characteristics of the resultant titania thin lms were studied using X-raydiraction (XRD) analysis, N2-adsorption/desorption analysis, and transmission electron microscopy (TEM). XRD and TEMinvestigations on the as-synthesised lms revealed the appearance of cubic-like, pseudohexagonal, and lamellar mesophases;depending on the amount of water in the sols of lm precursors. Template removal by a calcination process yields high surface area(320360 m2/g) mesoporous materials with crystalline anatase frameworks. Water content also inuences the degree of anatasecrystallinity of the calcined lms. Higher water content resulted in improved anatase crystallinity. These nanostructured materialsare of interest for photocatalysts, photoelectrochemical solar cells and other photonic devices.

Variability of measured modal frequencies of a cable-stayed bridge under different wind conditions

Y.Q. Ni,J.M. Ko,X.G. Hua,H.F. Zhou 국제구조공학회 2007 Smart Structures and Systems, An International Jou Vol.3 No.3

A good understanding of normal modal variability of civil structures due to varying environmental conditions such as temperature and wind is important for reliable performance of vibration-based damage detection methods. This paper addresses the quantification of wind-induced modal variability of a cable-stayed bridge making use of one-year monitoring data. In order to discriminate the wind-induced modal variability from the temperature-induced modal variability, the one-year monitoring data are divided into two sets: the first set includes the data obtained under weak wind conditions (hourly-average wind speed less than 2 m/s) during all four seasons, and the second set includes the data obtained under both weak and strong (typhoon) wind conditions during the summer only. The measured modal frequencies and temperatures of the bridge obtained from the first set of data are used to formulate temperature-frequency correlation models by means of artificial neural network technique. Before the second set of data is utilized to quantify the wind-induced modal variability, the effect of temperature on the measured modal frequencies is first eliminated by normalizing these modal frequencies to a reference temperature with the use of the temperature-frequency correlation models. Then the wind-induced modal variability is quantitatively evaluated by correlating the normalized modal frequencies for each mode with the wind speed measurement data. It is revealed that in contrast to the dependence of modal frequencies on temperature, there is no explicit correlation between the modal frequencies and wind intensity. For most of the measured modes, the modal frequencies exhibit a slightly increasing trend with the increase of wind speed in statistical sense. The relative variation of the modal frequencies arising from wind effect (with the maximum hourly-average wind speed up to 17.6 m/s) is estimated to range from 1.61% to 7.87% for the measured 8 modes of the bridge, being notably less than the modal variability caused by temperature effect.

Effect of CoO additive on structure and electrical properties of (Na_0.5Bi_0.5)_0.93Ba_0.07TiO₃ ceramics prepared by the citrate method

Xu, Q.,Chen, M.,Chen, W.,Liu, H.X.,Kim, B.H.,Ahn, B.K. Elsevier Science 2008 ACTA MATERIALIA Vol.56 No.3

(Na<SUB>0.5</SUB>Bi<SUB>0.5</SUB>)<SUB>0.93</SUB>Ba<SUB>0.07</SUB>TiO<SUB>3</SUB> ceramics with added 0-0.8 wt.% CoO were prepared by a citrate method and the influence of the CoO additive on the structure and electrical properties of the ceramics was investigated. All the specimens maintained a rhombohedral-tetragonal phase coexistence in crystal structure and the addition of CoO caused a remarkably promoted grain growth. Adding CoO led to a disappearance of the response in the dielectric constant (ε<SUB>r</SUB>) to the ferroelectric-antiferroelectric transition and increased the diffuseness of the dielectric constant peak around 230<SUP>o</SUP>C. Polarization-electric field hysteresis loops at varied temperatures revealed that adding CoO served to increase the depolarization temperature (T<SUB>d</SUB>). The addition of CoO tailored the dielectric, piezoelectric and ferroelectric properties at room temperature basically following a hard doped effect. The specimen with 0.8 wt.% CoO added showed a low dissipation factor (tanδ) of 0.8% and a high mechanical quality factor (Q<SUB>m</SUB>) of 297 while retaining a piezoelectric constant (d<SUB>33</SUB>) of 137 pC N<SUP>-1</SUP>.

High-efficiency p–i–n organic light-emitting diodes with a novel n-doping electron transport layer

Wei Xu,M.A. Khan,Yu Bai,X.Y. Jiang,Z.L. Zhang,W.Q. Zhu 한국물리학회 2009 Current Applied Physics Vol.9 No.4

We demonstrate p–i–n organic light-emitting diodes (OLEDs) incorporating an n-doping transport layer which comprises 8-hydroxy-quinolinato lithium (Liq) doped into 4'7-diphyenyl-1,10-phenanthroline (Bphen) as ETL and a p-doping transport layer which includes tetrafluro-tetracyano-quinodimethane (F4-TCNQ) doped into 4,4',4''-tris(3-methylphenylphenylamono) triphenylamine (m-MTDATA). In order to examine the improvement in the conductivity of transport layers, hole-only and electron-only devices are fabricated. The current and power efficiency of organic light-emitting diodes have been improved significantly after introducing a novel n-doping (Bphen: 33 wt% Liq) layer as an electron transport layer (ETL) and a p-doping layer composed of m-MTDATA and F4-TCNQ as a hole transport layer (HTL). Compared with the control device (without doping), the current efficiency and power efficiency of Device C (most efficient) is enhanced by approximately 51% and 89%, respectively, while driving voltage is reduced by 29%. This improvement is attributed to the improved conductivity of the transport layers that leads to the efficient charge balance in the emission zone. We demonstrate p–i–n organic light-emitting diodes (OLEDs) incorporating an n-doping transport layer which comprises 8-hydroxy-quinolinato lithium (Liq) doped into 4'7-diphyenyl-1,10-phenanthroline (Bphen) as ETL and a p-doping transport layer which includes tetrafluro-tetracyano-quinodimethane (F4-TCNQ) doped into 4,4',4''-tris(3-methylphenylphenylamono) triphenylamine (m-MTDATA). In order to examine the improvement in the conductivity of transport layers, hole-only and electron-only devices are fabricated. The current and power efficiency of organic light-emitting diodes have been improved significantly after introducing a novel n-doping (Bphen: 33 wt% Liq) layer as an electron transport layer (ETL) and a p-doping layer composed of m-MTDATA and F4-TCNQ as a hole transport layer (HTL). Compared with the control device (without doping), the current efficiency and power efficiency of Device C (most efficient) is enhanced by approximately 51% and 89%, respectively, while driving voltage is reduced by 29%. This improvement is attributed to the improved conductivity of the transport layers that leads to the efficient charge balance in the emission zone.

Variability of measured modal frequencies of a cable-stayed bridge under different wind conditions

Ni, Y.Q.,Ko, J.M.,Hua, X.G.,Zhou, H.F. Techno-Press 2007 Smart Structures and Systems, An International Jou Vol.3 No.3

A good understanding of normal modal variability of civil structures due to varying environmental conditions such as temperature and wind is important for reliable performance of vibration-based damage detection methods. This paper addresses the quantification of wind-induced modal variability of a cable-stayed bridge making use of one-year monitoring data. In order to discriminate the wind-induced modal variability from the temperature-induced modal variability, the one-year monitoring data are divided into two sets: the first set includes the data obtained under weak wind conditions (hourly-average wind speed less than 2 m/s) during all four seasons, and the second set includes the data obtained under both weak and strong (typhoon) wind conditions during the summer only. The measured modal frequencies and temperatures of the bridge obtained from the first set of data are used to formulate temperature-frequency correlation models by means of artificial neural network technique. Before the second set of data is utilized to quantify the wind-induced modal variability, the effect of temperature on the measured modal frequencies is first eliminated by normalizing these modal frequencies to a reference temperature with the use of the temperature-frequency correlation models. Then the wind-induced modal variability is quantitatively evaluated by correlating the normalized modal frequencies for each mode with the wind speed measurement data. It is revealed that in contrast to the dependence of modal frequencies on temperature, there is no explicit correlation between the modal frequencies and wind intensity. For most of the measured modes, the modal frequencies exhibit a slightly increasing trend with the increase of wind speed in statistical sense. The relative variation of the modal frequencies arising from wind effect (with the maximum hourly-average wind speed up to 17.6 m/s) is estimated to range from 1.61% to 7.87% for the measured 8 modes of the bridge, being notably less than the modal variability caused by temperature effect.

Spirulina sp. biomass dried/disrupted by different methods and their application in biofilms production

Ana P. Q. Larrosa,Alisson S. Camara,Jaqueline M. Moura,Luiz A. A. Pinto 한국식품과학회 2018 Food Science and Biotechnology Vol.27 No.6

Arthrospira Spirulina biomass is a source of intracellular compounds with great commercial interest, such as phycocyanin and phenolic compounds. In this work, different cell disruption methods of the microalgae biomass dried in spouted bed and in conventional tray were performed, aiming lead to the better extraction yields of these compounds. The samples of both drying techniques with the most suitable cell disruption were used to biofilms production. FTIR, DSC, and SEM for all samples were performed. The samples dried in spouted bed with cell disruption by milling and by microwave showed the best results for the powder products, with phycocyanin contents of 75.0 and 85.4 mg g-1, and total phenolic compounds of 41.6 and 41.9 mg g-1, respectively. However, the tray drying/milling produced the biofilms with the best characteristics (tensile strength of 3.69 MPa and water vapor permeability of 1.67 9 10-11 g m s-1 m-2 Pa-1) and the highest thermal stability.