Mean Transmittance Research Articles

Transparent conductive gallium-doped indium oxide nanowires for optoelectronic applications

Undoped and Ga-doped In2O3 nanowires (NWs) were synthesized by using vapor-liquid-solid (VLS) growth and were characterized as transparent conductive oxides for future generations of optoelectronic devices. A low amount of Ga was obtained due to the low solubility of Ga2O3 in In2O3. The incorporation of Ga into In2O3 nanowires decreases the grain size, the transmittance and the optical band gap. The Ga-doped In2O3 NWs exhibited a low sheet resistance of 12.2 ± 2 Ω/▭ and a mean transmittance value in the visible region of 77.1, which favor its use as a promising transparent conductive oxide.

Transparent and conductive indium doped cadmium oxide thin films prepared by pulsed filtered cathodic arc deposition

Indium doped cadmium oxide (CdO:In) films with different In concentrations were prepared on low-cost glass substrates by pulsed filtered cathodic arc deposition (PFCAD). It is shown that polycrystalline CdO:In films with smooth surface and dense structure are obtained. In-doping introduces extra electrons leading to remarkable improvements of electron mobility and conductivity, as well as improvement in the optical transmittance due to the Burstein–Moss effect. CdO:In films on glass substrates with thickness near 230nm show low resistivity of 7.23×10−5Ωcm, high electron mobility of 142cm2/Vs, and mean transmittance over 80% from 500 to 1250nm (including the glass substrate). These high quality pulsed arc-grown CdO:In films are potentially suitable for high efficiency multi-junction solar cells that harvest a broad range of the solar spectrum.

High conductivity nickel oxide thin films by a facile sol–gel method

Li-doped NiO thin films (Li:NiO) were deposited on glass substrates using a facile sol–gel method. The effects of Li doping concentration on the structural, electrical and optical properties of Li:NiO films were examined. The structural properties of Li:NiO films were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy. XRD revealed the Li:NiO films to have a polycrystalline bunsenite structure. The surface morphology of the Li:NiO films exhibited nanocrystalline grains with a randomly oriented morphology. The resistivity decreased substantially to 1.33kΩcm at 0.11mol%, which is one order of magnitude lower than that of the undoped NiO film. The mean transmittance decreased from 70% to 60% with increasing Li doping concentration from 0.02mol% to 0.19mol%.

Co-sputtered ZnO:Si thin films as transparent conductive oxides

Silicon doped Zinc Oxide thin films, so-called SZO, were deposited at room temperature on glass and plastic substrates by co-sputtering of ZnO and SiO2 targets. The influence of the SiO2 target power supply (from 30 to 75W) on the SZO thin film composition and crystallinity is discussed. Si/Zn atomic ratio, determined by X-ray microprobe, increases from 1.2 to 8.2at.%. For Si/Zn ratio equal and lower than 3.9%, SZO (S3.9ZO) thin films exhibit the Wurzite structure with the (0 0 2) preferred orientation. Larger Si content leads to a decrease in crystallinity. With Si addition, the resistivity decreases down to 3.5×10−3Ω·cm for SZO thin film containing 3.9at.% of Si prior to an increase. The mean transmittance of S3.9ZO thin film on glass substrate approaches 80% (it is about 90% for the film itself) in the visible range (from 400 to 750nm). Co-sputtered SZO thin films are suitable candidates for large area transparent conductive oxides.

Characteristics of Solar Radiation and the Impact of Clouds at Yangbajing, Tibet

AbstractYangbajing (YBJ) is located in the Tibetan Plateau, China. The characteristics of solar radiation and its relationship with clouds at YBJ from April 2009 to April 2010 were analyzed in this paper. The annual mean solar radiation was 478.4 W m-2 , and the annual mean transmittance was 0.713. The atmospheric mean transmittance of clear skies reaches 0.828 when the solar elevation angle (SEA) is greater than 10 degrees. Comparisons with numerical simulations show that the atmosphere of YBJ is clean. Impacts from atmospheric conditions on solar radiation are similar for clear skies during the year because the standard deviation of transmittance in clear skies was less than 0.05 when the SEA was greater than 10 degrees. It is important to understand the impact of clouds on solar radiation without considering other impact factors. In the last part of this article, the authors analyzed and established a statistical quantitative relationship between surface solar radiation and cloud fraction.

Phase Dependent Distortion in Direct Conversion Transmitters

The impairments and nonlinear (NL) distortion generated by the analog quadrature modulator in a direct conversion transmitter affect the performance of a transmission system. These effects cause input signal dependent gain variations at the low-pass equivalent I/Q-modulator output. The aim of this paper is to analytically derive the relationship between the mean transmitter gain and the tone phases of single- or two-tone excitation signals. This relationship is separately evaluated for the different distortion sources in the direct conversion transmitter. It will be shown that only two-tone signals with frequencies symmetrical to DC are able to excite these phase-dependent gain variations. Additionally, the conditions for the presence of the distortion mechanisms are highlighted. Using measurements of an experimental transmitter setup, the validity of the derived results is shown. The presence of phase-dependent gain changes were also measured when applying a DC-symmetric multi-tone signal.

Diversity incorporated energy adaptation for A-CDMA systems over slow fading channels

In this paper, a theoretical analysis of diversity incorporated Variable Energy Adaptation (VEA) in an Asynchronous Code Division Multiple Access (A-CDMA) system is discussed for Rayleigh, Rician and Nakagami slow fading channels. The adaptation is accomplished by providing the receiver with the capability of measuring the signal energy-to-noise ratio, and controlling the transmitted signal energy by means of a noise-free feedback loop. System parameters such as fading margin, maximum signal-to-noise ratio, and mean transmitter energy gain are derived and plotted for fading channels as a function of the probability of error specification and the probability of unsatisfactory operation. The mean and median probabilities of error are plotted as a function of energy-to-noise ratios for different fading channels. Error probability distribution and density functions are derived and plotted for various signal-fading distributions.

Effects of growth temperature on structure and electrical properties of dielectric (Ba,Sr)TiO 3 capacitors with transparent conducting oxide electrodes

200 nm-thick BST thin films were grown on Zr-doped In 2O 3/SrTiO 3 (1 0 0) substrates at 550–750 °C. X-ray diffraction results show that the as-deposited BST films were polycrystalline with random crystallographic orientations. X-ray diffraction patterns reveal that the BST film grown at 650 °C had the best crystalline quality of all the deposition temperatures. Atomic force microscopy and secondary ion mass spectrometry showed that the surface and interface structures of the BST films became rough as the growth temperature increased. The BST film grown at 650 °C showed the best electrical properties, with a dielectric constant of 420 at 1 MHz, dielectric tunability of 32.1%, dielectric loss of 0.015 at 300 kV/cm, and a mean optical transmittance in visible wavelength of 71.3%.

Broadband antireflection of block copolymer/homopolymer blend films with gradient refractive index structures

The factors that influence the broadband antireflection of block copolymer/homopolymer blend films were systematically investigated. The gradient refractive index structure, which was generated by removing the PMMA content from a film of PS-b-PMMA/PMMA blends, contributed to the broadband antireflection. The volume fraction of the PMMA block (fPMMA), the total degree of polymerization (N) and the weight percent of the homopolymer played a key role in the formation of the gradient porosity index inner structure. By increasing χN, the PS porous structure was kept from collapsing after removal of the PMMA domain, which led to a stable gradient porosity ratio structure and higher transmittance. While increasing fPMMA, the PMMA domains changed from a dispersed phase to a continuous phase, which caused the residual PS structure to collapse more easily and the transmittance decreased. The best broadband antireflective properties were achieved from the 45 mg mL−1 solution of PS-b-PMMA (Mn = 68 000–33 500, fPMMA = ∼25%) blended with 30 wt% PMMA: a mean transmittance of 98.4% at full spectrum, and >98.0% in the visible–NIR range between 600 nm and 2000 nm.

Inhibitory Effects of Ticagrelor Compared With Clopidogrel on Platelet Function in Patients With Acute Coronary Syndromes: The PLATO (PLATelet inhibition and patient Outcomes) PLATELET Substudy

The PLATO (PLATelet inhibition and patient Outcomes) PLATELET substudy aimed to compare the antiplatelet effects of clopidogrel and ticagrelor in patients with acute coronary syndromes.The PLATO study demonstrated superiority of ticagrelor over clopidogrel in the prevention of ischemic events in patients with acute coronary syndromes.Patients were randomized to receive either clopidogrel (300- to 600-mg loading dose [LD], 75 mg/day) or ticagrelor (180-mg LD, 90 mg twice daily). The effects of maintenance therapy were studied in 69 patients pre- and 2 to 4 h post-dose after at least 28 days. The LD effect was studied in 24 clopidogrel-naive patients. Light transmittance aggregometry (adenosine diphosphate 5 to 20 μM), VerifyNow P2Y12, and VASP phosphorylation assays were performed.During maintenance therapy, ticagrelor achieved greater suppression of platelet reactivity compared with clopidogrel. The mean maximum light transmittance aggregometry responses (adenosine diphosphate 20 μM) post-maintenance dose were 44±15% for clopidogrel and 28±10% for ticagrelor (p<0.001). High platelet reactivity was seen more frequently in the clopidogrel group. Proton pump inhibitor use was associated with higher platelet reactivity with clopidogrel but not ticagrelor. The ticagrelor LD also achieved greater inhibition of platelet aggregation compared with the clopidogrel LD.Ticagrelor achieves greater antiplatelet effect than clopidogrel in patients with acute coronary syndromes, both in the first hours of treatment and during maintenance therapy.

Remote sounding of atmospheric pressure profile from space, part 2: channel selection

The expressions are derived for both the sensitivity of retrieved surface pressure and that of radiance measurement to atmospheric temperature profile in detail. Calculations indicate that the later should not be regarded as one of bases for channel selection. After removing channels with very large maximal relative fitting errors of atmospheric transmittance model and mean transmittance model, weak absorption channels and channels with higher sensitivity of retrieval surface pressure to atmospheric temperature profile, the remote sounding accuracy of surface pressure with 1000 hPa is improved by about 3.2~21hPa.

Effects of citric acid on properties of single phase CuAlO 2 thin films derived by chemical solution deposition

Single phase CuAlO 2 thin films were first successfully prepared on (0 0 0 1) sapphire substrates by chemical solution deposition method. Additionally, in order to improve the transmittance and conductivity of single phase CuAlO 2 thin films, effects of citric acid as additive on phase structure, morphology and optical–electrical property of CuAlO 2 thin films were investigated. Appropriate contents of citric acid do not inhibit the formation of single phase CuAlO 2 thin films, and are also in favor of improvement of transmittance. Excessive citric acid not only introduces secondary phases, but also deteriorates the quality of the film surface. The mean transmittance in visible region is approximately 50% in the film prepared with 5 unit contents of citric acid and its direct and indirect optical band gaps are 3.24 eV and 1.8 eV, respectively. The films with or without citric acid behave like semiconductors. The resistivity and the activation energy of the film prepared with 5 unit contents of citric acid are evaluated as 2.5 × 10 2 Ω cm at 290 K and 300.5 meV, respectively.

Patterning of multilayer dielectric optical filters using metal masks fabricated by electroforming and photolithography

Ni films, replacing photoresists, serve as masks in the selective deposition of optical thin films by electron-beam gun evaporation at a substrate temperature of 300°C. Photolithography is adopted herein to define the growth of Ni films by electroforming. Mosaic patterns with a width of 20 µm are employed as red color filters, which are longwave pass. These red filters are formed from alternate SiO2 and TiO2 layers and have a mean transmittance of >90%. The experimental results show that the combined use of photolithography, electroforming, and electron-beam gun evaporation can deposit miniaturized multilayer dielectric coatings with high light transmittance in a hot process.

Changes on transmittance mode of different composite resins

The purpose of this study was to evaluate the transmittance of seven different composite resins. Ten specimens were prepared (10 mm diameter, 2 mm thickness) for each experimental group, as follows: G1- Charisma® A2 (Heraeus-Kulzer); G2- FiltekTM Supreme A2E (3M/ESPE); G3- FiltekTM Supreme A2B (3M/ESPE); G4-FiltekTM Supreme YT (3M/ESPE); G5- Esthet-X® A2 (Dentsply); G6- Esthet-X® YE (Dentsply); G7- Durafill® A2 (Heraeus-Kulzer) and G8- FiltekTM Z-100 A2 (3M/ESPE). The transmittance mode was measured using a UV-visible spectrophotometer (Cary Instruments) at 400-760 nm. The specimens were evaluated at three different times: zero hour (initial), 24 hours and 10 days after immersion in artificial saliva. The differences in transmittance were determined by two-way analysis of variance (ANOVA) and Tukey's test. The various composite resins showed significant differences in the wavelength dependence of transmittance. The mean values of transmittance increased significantly, with wavelengths increasing from 400 to 760 nm. The performance of the experimental groups was similar in terms of immersion time, considering that at time zero and after 10 days, all the groups showed similar results, which were statistically higher than the values obtained after 24 hours of immersion. The FiltekTM Supreme YT composite resin presented the highest mean transmittance values along the wavelengths at the three measured times. Esthet-X® YE and Durafill® yielded similar mean transmittance values, which were higher than those of the other groups. This study shows that the transmittance values of composite resins are directly related with the type, size and amount of inorganic filler particles.

Enhanced hardness in B-doped ZnO thin films on fused quartz substrates by pulsed-laser deposition

B-doped ZnO thin films have been fabricated on fused quartz substrates using boron–ZnO mosaic target by pulsed-laser deposition technique, and the mechanical properties have been studied by nanoindentation continuous stiffness measurement technique and transmission electron microscope (TEM). Nanoindentation measurement revealed that the hardness of B-doped ZnO films, 9.32±0.90 to 12.10±1.00GPa, is much greater than that of undoped ZnO films and very close to that of traditional semiconductor Si. The mean transmittance (%) is larger than 81% in the visible range (380–780nm) for all the films, and the Hall effect measurement showed that the carrier density is around 2×1020cm−3 and the resistivity lower than 3×10−3Ωcm. TEM characteristics show undoped thin films have more amorphous area between grains while the B-doped ZnO films have thin grain boundaries. We suggest that the grain boundaries act as the strain compensation sites and the decrease in thickness of grain boundaries enhances the hardness of the B-doped ZnO films.

Radiação solar em ambiente protegido cultivado com tomateiro nas estações verão-outono do Rio Grande do Sul

O crescimento e desenvolvimento de uma planta dependem da intensidade, qualidade e duração da radiação solar. Por esse fator ser de importância vital às plantas, o presente trabalho objetivou fazer uma avaliação sobre sua variação, bem como sobre a sua disponibilidade no interior do ambiente protegido durante o ciclo do tomateiro nas estações verão-outono em Pelotas, Rio Grande do Sul. O experimento foi conduzido de janeiro a junho de 2003 no Campus da Universidade Federal de Pelotas (latitude 31°52'S; longitude 52°21'W e altitude de 13m), em estufa plástica disposta no sentido Leste-Oeste, com área de 180m². A cultivar utilizada foi "Flora-dade", semeada em 24/01/03, transplantada no dia 28/02/03, sendo a última colheita em 12/06/03. Avaliou-se a radiação solar global externa (Rgext) e interna (Rgint), transmitância, radiação fotossinteticamente ativa (RFA) e o albedo da cultura a partir de sensores eletrônicos conectados a um "datalloger". Durante o ciclo da cultura, o total de Rgext foi 1161,21MJ m-2, enquanto a Rgint foi 881,85MJ m-2. A Rgint e a RFA apresentaram valores médios diários de 8,5MJ m-2 dia-1 e 3,4MJ m-2 dia-1, respectivamente. A transmitância média da cobertura plástica à radiação solar global foi de 76%. O albedo médio diário da cultura foi 0,23, com albedo de 0,17 nos estádios iniciais, 0,26 no período de máximo crescimento e 0,23 no final do ciclo.

Gaussian-beam weak scintillation on ground-to-space paths: compact descriptions and Rytov-method applicability

Recent papers comparing weak-scintillation data from wave- optics simulations with predictions derived from the Rytov perturbation method for ground-to-space Gaussian beams have revealed a region of inaccuracy in the Rytov-based predictions. The discrepancy region is defined by beam diameter and focus settings that place the target in the beam far field and the turbulence in the transmitter near field. Under such conditions turbulence-induced beam wander dominates the scintil- lation at the target. We develop a solution to the turbulent propagation physics that is applicable in the discrepancy region, and demonstrate agreement in scintillation behavior with our own wave-optics simulation data and with predictions from a rigorous extended Huygens-Fresnel analysis. A combination of our solution and Rytov-based scintillation theory can be used to yield accurate scintillation predictions throughout the weak-scintillation regime for ground-to-space beams. Separately, we show that Rytov-based scintillation theory best describes the physics of a wander-tracking transmitter where beam wander has been removed from the propagation physics at the mean transmitter aim point on the target plane, as opposed to the physics of a stationary transmitter. © 2005

Variable energy adaptation for asynchronous CDMA communications over slowly fading channels

In this paper, a detailed theoretical analysis of variable energy adaptation in an asynchronous code division multiple access (A-CDMA) system is discussed. Rayleigh and Rician frequency-selective slowly fading channels are considered. The receiver, capable of measuring the received signal energy-to-noise ratio, provides the transmitter with the necessary signal-to-noise ratio measurement to control the transmitter energy through a noise-free feedback channel. System parameters such as fading margin and mean transmitter energy gain are calculated for both Rayleigh and Rician fading channels as a function of the probability of error specification and the probability of unsatisfactory operation.

56 Hsp90-targeted therapy for small cell lung cancer

Pb(Zr0.52Ti0.48)O3 ferroelectric thin films were in situ deposited on FTO glass substrate by RF magnetron sputtering process at low substrate temperature of 260 °C, through optimizing the process parameters of sputtering power, sputtering gas pressure, and substrate temperature. Ferroelectric properties, surface morphology, and optical transmittance of PZT thin films are investigated by standardized ferroelectric test system, atomic force microscope, and UV–Vis spectrometer, respectively. The results show that the sample deposited at 260 °C exhibits ferroelectric properties with Pr and Ps of 3.86 μm/cm2 and 8.85 μm/cm2, respectively. The arithmetic average roughness PZT thin film is 95.9 nm. Interestingly, the mean transmittance of the sample is above 80% in the visible light range.

Remote sensing and the optical properties of the narrow cylindrical leaves of juncus roemerianus

To develop a more complete foundation for remote sensing of the marsh grass Juncus roemerianus, we measured the optical properties of its cylindrical leaves at sites of different canopy height, biomass composition and amount, and connectivity to ocean flushing. To measure the leaf optical properties, we adapted a technique used for conifer needles. After establishing the reliability and limits of the adapted technique to the wider J.roemerianus leaves, mean transmittance and reflectance spectra were compared to associated leaf diameters from two dates in 1999 and 2002 and at each site. Transmittance was inversely related to leaf diameter. Mean transmittance and reflectance generated from reoccupation of many field sites in 2002 indicated little or no difference in transmittance between years, a slight reflectance difference in the visible (<2%) and a slightly higher reflectance difference in the near infrared (NIR) (<4%). Site comparison indicated limited ability to separate leaf transmittance but not reflectance by marsh type (e.g., low, medium, high) or biomass. Excluding one outlier, we found leaf transmittances could be adequately represented as 1% /spl plusmn/ 0.2% in the visible and 9% /spl plusmn/ 1% in the NIR and leaf reflectances represented from 14% to 16% in the visible and 71% to 75% in the NIR (the reflectance ranges represent 1999 and 2002 means). Reflectance and transmittance spectra associated with the dead J. roemerianus leaves displayed a spectrally flat increase from the visible to the NIR wavelengths. In total, we documented the atypical optical properties of the cylindrical J. roemerianus leaves and showed that to a first approximation, single means could represent leaf transmittance and visible leaf reflectance across all marsh zones and, after accounting for sample standardization, possibly the NIR reflectance as well.