Plexiglass Substrates Research Articles

Design and fabrication of a super-wideband transparent antenna implanted on a solar cell substrate

In this study, an antenna with transparent super wideband CPW technology has been designed and built with the combination of solar panels for use in wireless communication equipment and systems that require mobile power. The transparency value of the antenna is 63.3%, which is an acceptable value for the optimal use of sunlight. The proposed antenna was designed and measured on a plexi-glass substrate with a dielectric constant of {{varvec{upvarepsilon}}}_{{varvec{r}}}=4.4 and various thicknesses, the proposed antenna was designed and measured. The copper sheet has a high electrical conductivity and therefore it was selected for the antenna's radiating component as compared to earlier techniques that employed metal oxide. All simulations were done with CST microwave studio software and frequency domain solver. The results indicated that the antenna's operating frequency ranges from 2 to 32 GHz. The results of the computations indicated that the antenna's peak gain and peak efficiency are 8.1 dB and 90%, respectively. Various multiple-input and multiple-output (MIMO) performance parameters, including the envelope correlation coefficient (ECC), diversity gain (DG), average effective gain (MEG), total active reflection coefficient (TARC), and channel capacity loss (CCL), were analyzed to demonstrate the antenna's performance.

Marmara Denizi'nde İzmit Körfezinde Ağır Metal Toksisitesinin, Pleksiglas Substratta Biyofilm Oluşumu ile Biyoizlenmesi

In this study, plexiglas substrates were used for biofilm formation to observe short-term variations in heavy metals in Izmit Gulf. The substrates were inserted and collected in a two-week period as three times in the autumn season. The averaged accumulation values of metals were decreased in the order of Fe>Mn>Zn>Cu>Pb>Cr>Ni>Cd. The same trend was observed in the first and third samples of the autumn without any exception in the sequence. The order for the second sample was as Fe>Mn>Zn>Pb>Cr>Cu>Ni>Cd. Among the 37 species found, 22 belonged to Bacillariophyceae, 2 species to Cyanophyceae and 13 species to Dinophyceae taxa. While Bacillariophyceae consisted of about 55 % of total colony, 38 % and 7 % comsosed of species of Dinophyceae and Cyanophyceae taxa, respectively. Total biodensity values are 22362, 23513 and 21348 cell/ml. For various incubation days (15, 30 and 45), it was seen that increasing incubation time would not always result in the increase in densities of all species and total density of biofilms. Metal levels did not show big variations. Low correlations were observed in relative abundances of first three dominant species occupying around 85 % of total algal community with some metals, though the variations are not much significant.

Surface coverage by impact of droplets from a monodisperse spray

A novel pneumatic monodisperse spray was fabricated to validate the results of a probabilistic model and a stochastic model that were developed to predict surface area coverage of the monodisperse spray. Multiple droplets of a highly viscous 87 wt% aqueous glycerin solution were deposited on a flat, transparent, plexiglass substrate. The uniformly sized droplets (2.5 mm in diameter) impacted, spread, and coalesced on the substrate which led to the creation of a liquid sheet. Using a high-speed camera placed underneath the transparent substrate, droplet impact and resultant area coverage were recorded. When impinging droplets overlapped those already on the surface, surface tension forces pulled impacting droplets towards them, agglomerating the liquid, in a phenomenon known as drawback. The area covered by the liquid was measured from photographs using image analysis software. In the numerical models, droplets were set to impinge at random locations and drawback effects between droplets were accounted for by using a semiempirical correlation. While both models showed good agreement with the experimental results at lower area fractions, the stochastic model gave better estimates at larger area fraction due to its incorporation of drawback effects.

Dual band transparent antenna for wireless MIMO system applications

AbstractA dual‐band optically transparent antenna based on a slotted interconnected ring resonator as an efficient radiating element is proposed. The compact radiating element and partial ground plane are structured on a plexiglass substrate with Silver Tin Oxide as transparent conducting material. The radiation disadvantage of OTAs due to the low conductivity of conductive oxides has been overcome with the gain improvement technique of 2 × 1 antenna array design. The overall sizes of the proposed single element and 2 × 1 two element array antennas are λ/2.5 × λ/2.5 and λ/1.19 × λ/2.08 at the lower resonance frequency of 2.4 GHz, respectively. The operation bands of both OTA prototypes cover WLAN and WiMAX frequency bands with permissible bandwidth and sufficient gain therefore the 2 × 1 antenna array is utilized as one of two dual‐band antennas of a 2 × 2 MIMO transceiver system for WLAN and WiMAX band operations.

Compact wideband transparent antenna for 5G communication systems

AbstractA compact wideband transparent antenna designed on plexiglass substrate (10 × 12 × 1.48 mm3) is presented. The optically transparent antenna consists of a radiation patch and a ground plane fabricated using AgHT‐8. The antenna design comprises of rectangular shaped branches optimized to attain the wideband characteristics. The proposed antenna design has impedance bandwidth of 58.71% covering the frequency range of 23.92‐43.8 GHz. The radiation pattern of the proposed antenna shows directional radiation pattern with electrical tilt. All calculated and measured results show that proposed compact transparent antenna is an excellent candidate for 5G communication systems and wideband code division multiple access applications.

Effect of in-stream physicochemical processes on the seasonal variations in δ13C and δ18O values in laminated travertine deposits in a mountain stream channel

Travertines are potential archives of continental paleoclimate. Records of stable carbon and oxygen isotopic composition (δ13C and δ18O) in laminated travertine deposits from endogene spring waters show regular cyclic patterns which may be due to seasonal change in climate determinants such as temperature and rainfall. In this study, δ13C and δ18O measurements of three travertine specimens that grew naturally over the eight years, 2004–2011, at upstream, middle and downstream sites in a canal at Baishuitai, SW China, are presented. They exhibit clear seasonal variations that generally correlate with biannual laminations. Specifically, δ13C and δ18O values show significant positive correlation with each other for the three travertine specimens, with the correlation coefficients increasing downstream along the canal. To reveal the factors governing the seasonal and spatial variations in δ13C and δ18O values, newly formed travertines precipitated on Plexiglas substrates are also examined. Both δ13C and δ18O of the substrate travertines are low in the summer/rainy season and high in the winter/dry season, showing a great consistency with the patterns in the natural travertines. Spatially, isotope values increase downstream in both seasons, with higher increase rates in winter that are related to removal of larger fractions of dissolved inorganic carbon (DIC) from the solution and stronger kinetic isotopic fractionation in winter. Due to in-stream physicochemical processes, including CaCO3 precipitation and the associated degassing of CO2, seasonal changes in δ13C and δ18O in the travertines are amplified by two times between the upstream and downstream sites: this is opposite to trends for epigene (meteogene) tufas whose seasonal changes in stable isotope compositions are reduced downstream. We suggest in-stream physicochemical processes are a potential reason for underestimation of annual temperature ranges that are inferred from epigene tufa δ18O data.

On the hot electrons and Kα x-rays generation in the intense laser interaction with silver targets

Intensity dependence of the conversion efficiency of laser energy into the energy of hot electrons is determined with the aid of measurements and modeling of Kα-photon yield from silver targets irradiated by relativistically intense subpicosecond laser pulses. We take into account intensity dependence of the effective hot electron temperature assuming the Wilks’ scaling. The measurements reveal approximately the same values of the Kα yield from a silver foil of 10 μm thickness, attached onto aluminium or plexiglass substrates, at the intensities about 1018 W/cm2 and 2 × 1019 W/cm2. Intensity dependence of the Kα yield from the silver foil, calculated using determined conversion efficiency of laser energy into the energy of hot electrons, is in agreement with the measurements.

An Optimized Circuit in Plastic Meander Line Antenna for 2.45 GHz Applications

Researchers seek to design electrically small planar antennas for RFID applications. Using multiparameter optimization, various meander line antennas were designed for the lowest resonant frequency and maximum radiation efficiencies for a fixed grid size. One such design for highest radiation efficiency was optimized for microwave frequencies by including an impedance matching structure. The antenna was printed with silver ink on a plexiglass substrate using the circuit in plastic (CiP) technique of embedded electrical components. The measured scattering parameter (S11) was −18.43 dB at resonance. The radiation efficiency of the antenna measured using simple and improved Wheeler cap method was 74.4/74.1%. The radiation pattern of electrically small CiP antenna was doughnut-shaped with main lobe magnitude of 0.453 dB and an angular width of 84.2° in elevation plane. The measured 10 dB fractional bandwidth of the antenna was 18.98%. The results are compared with silver/copper in air antennas optimized for achieving the highest radiation efficiency for a fixed grid size. Plastic antennas are viable at microwave frequencies.

Are Gas Discharges Capable of Generating Maser Radiation?:—Part 2

Microwave radiation produced by the sliding (spark channel) discharges in the small gaps under the action of high (>MV/cm) electric field over the dielectric (plexiglass) substrates are studied in hydrogen/argon mixtures. Under certain condition, it is observed that the frequency of the radiation in the resonant cavity is 1.420 GHz. This frequency is related to the intrinsic property of the hydrogen atoms and corresponds to the radiation produced by the atomic hydrogen maser. Few examples how the resonant cavity affects the radiation produced by the quantum states of various bands is presented. This paper suggests why the super radiance is sometimes observed. Effect of the microwave radiation on the security of the electronic infrastructure is also mentioned.

Fluorine-containing photocurable hybrid coatings via anhydrous sol-gel method

In this study, fluorine-doped photocurable hybrid coatings were prepared by combining UV-curing technology with an anhydrous sol–gel method. First, methacryloxymethyl triethoxysilane (MEMO) was hydrolyzed via an anhydrous sol–gel process. Then MEMO was mixed with acrylic oligomers and predetermined amounts of fluoroacrylate resin. UV curable hybrid coatings were applied on corona-treated plexiglass substrates. The addition of fluorine showed a significant impact on the properties of the coatings. As the fluorine content was increased in the formulations, flame retardancy and the contact angle values of the coatings increased. It was found that the optical transmittance of the coatings was higher than 95%. The surface morphology of the hybrid films was characterized by scanning electron microscopy (SEM). The chemical composition of the surface of the coatings was identified by energy dispersion spectrum (SEM–EDS) technique. SEM studies indicated that inorganic particles were dispersed homogenously throughout the organic matrix. J. VINYL ADDIT. TECHNOL., 2014. © 2014 Society of Plastics Engineers

Boron containing UV-curable epoxy acrylate coatings

In the present work boron acrylate monomer was synthesized by esterification reaction. UV-curable boron containing epoxy acrylate coatings were prepared and applied on plexiglass substrates to obtain thermally and mechanically stable coatings. The physical and mechanical properties of UV-cured coatings were investigated such as gel content, solvent resistance, hardness, flexibility and tensile tests. The thermal behavior of coatings was also evaluated. It was observed that the tensile properties and thermal stabilities of boron modified epoxy coatings mainly depend on the boron content.

Contrasts in variations of the carbon and oxygen isotopic composition of travertines formed in pools and a ramp stream at Huanglong Ravine, China: Implications for paleoclimatic interpretations

Water samples and modern endogenic (thermogene) travertine calcite deposited on plexiglass substrates in travertine pools and a ramp stream were collected along the Huanglong Ravine, Sichuan, SW China at regular ∼10day intervals from early May to early November in 2010, including both wet and dry conditions. Temporal and spatial variations in the δ13C and δ18O values of the modern travertine were examined to understand their potential for paleoclimatic and paleoenvironmental interpretations. It was found that δ13C and δ18O of travertine formed in the ramp stream were low in the warm rainy season and high in the cold dry season. Their positive correlation was mainly due to dilution and rainfall seasonal effects on δ13C and δ18O values, respectively, i.e., low δ13C values were caused by dilution by overland flow with depleted δ13C values and reduced CO2-degassing in the warm rainy season while low δ18O values of travertine were because of low δ18O values of water induced by seasonal variation in oxygen isotopic ratios of rainwater. Meanwhile, kinetic effect on oxygen isotopic fractionation during ramp travertine deposition existed and reduced this positive correlation. In contrast, the δ13C and δ18O values of the pool travertines displayed a converse behavior which was caused mainly by the temperature effect. Low δ18O values and high δ13C values in the warm rainy season were correlated chiefly with the higher water temperatures. Therefore, the δ13C and δ18O values of the travertine may be used for paleo-rainfall or paleotemperature reconstruction respectively. This study demonstrates that endogenic travertine, like epigenic (meteogene) tufa, may be a suitable candidate for high-resolution paleoclimatic and paleoenvironmental reconstructions. However, since travertines deposited under differing hydrodynamic conditions (e.g., pools with still water contrasted to fast flow streams) have different climatic responses, it is necessary to check the depositional facies of fossil travertine samples before they can be used for palaeoclimate (temperature and/or rainfall) reconstruction.

Naked Amoebae in Biofilms Collected from a Temperate Freshwater Pond

Biofilms collected on Plexiglass substrates, from a freshwater pond in northern New York State, were examined microscopically for naked amoebae densities, sizes, diversity, and estimated C-biomass. Five samples were obtained during summer 2006 and 2007. The densities ranged from 109 to 136/cm(2) biofilm surface and 285 to 550/mg biofilm dry weight. Sizes ranged from 13 to 200μm. Diversities ranged from 4.23 to 4.55. C-biomass ranged from 64 to 543ng C/cm(2) and 125 to 1,700μg C/g dry weight. Thirty morphospecies were identified among the five samples, including very large amoebae in the range of 100-200μm. Large amoebae (≥50μm) accounted for the largest proportion of the C-biomass.

Spatial–temporal variations of travertine deposition rates and their controlling factors in Huanglong Ravine, China – A world’s heritage site

Abstract Huanglong, well known for its unique natural travertine landscape, was listed by UNESCO as an entry in the World’s Nature Heritage in 1992, and attracts more than one million of tourists from all over the world each year. However, the landscape has undergone significant degradation (notably, serious decay of travertine) during the past two decades as the tourist numbers have increased remarkably. To understand the variations of travertine deposition rates and their controlling factors, especially the impact of tourism activities, paired water and modern travertine samples deposited on plexiglass substrates were taken along the Huanglong stream at regular intervals from early May to early November in 2010 (i.e., in the wet season). The travertine deposition rates have declined significantly compared to those in early 90s in all four subsystems in the Huanglong Ravine. The largest decrease (89.5%) occurred at the lowest sampling site. The reduction in travertine deposition most likely resulted from the phosphate pollution caused by the tourism activities. In spite of an increase in concentrations of Ca, calcite saturation, and water temperature, which facilitate calcite precipitation, deposition rates decreased because of inhibition by PO 4 3 - ions. Seasonally, three control patterns of travertine deposition rates were distinguished along the Ravine. They are control by water-temperature, control by dilution of rainwater and snow-melting water and control by PO 4 -inhibition of calcite precipitation.

Thermal and neutron shielding properties of 10B containing UV cured hybrid coatings

10B containing organic–inorganic hybrid coating material based on a UV-curable formulation was prepared via anhydrous sol–gel technique. UV curable coatings were applied on Plexiglas (PMMA) substrates. The molecular structure of the coating material was analyzed by ATR-FTIR spectroscopy technique. The characterization of the UV-curable coating was evaluated by various techniques such as gel content, abrasion resistance, chemical resistance, pencil hardness, pendulum hardness, MEK rubbing test, contact angle, cross-cut test, gloss, transmittance test, neutron absorption, Limiting Oxygen Index and stress–strain tests. Hybrid coatings showed a significant enhancement in radiation shielding properties. The thermal behavior of coatings was also evaluated. It is observed that the thermal stability of coatings mainly depends on their boron and silicate contents. Results of all analysis conducted on hybrid films, and coatings were discussed.

Preparation and characterization of UV‐curable, boron‐containing, transparent hybrid coatings

AbstractA series of ultraviolet (UV)‐curable, boron‐containing hybrid coatings were prepared by an anhydrous sol–gel technique from a mixture of an acrylated bisphenol A based epoxy resin, methacryloxymethyl triethoxysilane, and boric acid. The use of boric acid allowed the hydrolysis and condensation of hybrid silicon alkoxides without the further addition of water or a catalyst. The chemical structure of the boron‐containing hybrid coatings was characterized with Fourier transform infrared, real‐time infrared, and 29Si cross‐polarization/magic‐angle spinning NMR techniques. UV‐curable coatings were applied to polycarbonate and Plexiglas substrates. The physical and mechanical properties of the UV‐cured coatings (e.g., pendulum hardness, pencil hardness, contact angle, gel content, methyl ethyl ketone rubbing test, tensile test, abrasion resistance, chemical resistance, neutron absorption, and limiting oxygen index) were examined. The hybrid coatings showed a significant enhancement in their radiation‐shielding properties. The thermal behavior of the coatings was also evaluated. It was observed that the thermal stability of the coatings mainly depended on their boron and silicate contents. The results of all analyses of the free films and coatings were examined. © 2010 Wiley Periodicals, © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Synthesis of acetophenone formaldehyde resin containing ABA type block copolymers by ATRP

AbstractWell‐defined ABA type block copolymers of acetophenone formaldehyde resin (AFR) and methyl methacrylate (MMA) were synthesized via atom transfer radical polymerization. In the first step, acetophenone formaldehyde resin containing hydroxyl groups was modified with 2‐bromopropionyl bromide. Resulting difunctional macroinitiator was used in the ATRP of MMA using copper bromide (CuBr)/N,N,N′,N″,N″‐pentamethyl‐diethylenetriamine (PMDETA) as the catalyst system at 90°C. The chemical composition and structure of the copolymers were characterized by nuclear magnetic resonance (1H‐NMR) spectroscopy, Fourier transform infrared (FT‐IR) spectroscopy, and molecular weight measurement. Gel permeation chromatography (GPC) was used to study the molecular weight distributions of the AFR block copolymers. Mn up to 24,000 associated with narrow molecular weight distributions (PDI < 1.5) were obtained with conversions up to 79%. Coating properties of obtained block copolymers such as adhesion and reflectance values were investigated. They showed good adhesion properties on Plexiglass substrates. Reflectance values increased as the resin content of polymer increased. The thermal properties of all polymers were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). All block copolymers showed higher thermal stability than their precursor AFR resin. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Wet-dry seasonal variations of hydrochemistry and carbonate precipitation rates in a travertine-depositing canal at Baishuitai, Yunnan, SW China: Implications for the formation of biannual laminae in travertine and for climatic reconstruction

Biannually laminated freshwater carbonate deposits (tufas and travertines) are potential sources of high-resolution terrestrial paleoclimate data. In order to understand the processes of carbonate precipitation, the formation of the biannual laminae in endogenic (thermogene) travertine, and the characteristics of the climate information recorded in them, the seasonal variations of hydrochemistry and carbonate precipitation rates in a travertine-depositing canal at Baishuitai, Yunnan, SW China were investigated. Plexiglass substrates (5 cm × 5 cm × 0.5 cm) for carbonate collection were placed in the flowing water at ten sampling sites in the canal and replaced semimonthly for one hydrological year, to determine the rates of carbonate precipitation. Water temperature, pH and specific conductivity at these sampling sites were measured daily in situ throughout the year. From these data the concentrations of Ca2+, HCO3−, the calcite saturation index and CO2 partial pressure were derived. The hydrochemistry and rate of carbonate precipitation at all sites displayed the same clear seasonal pattern, lower in the warm rainy season and higher in the cold dry season. The lower solute chemical concentrations and carbonate precipitation rates in the rainy season were due to the dilution of ground water concentrations by overland flow after rainfall. The endogenic travertine had much clearer biannual lamination structure than is normal in the epigenic tufa in Japan. The lamina consisted of a thin dark porous warm-rainy-season layer alternating with a thick light dense cold-dry-season layer: in contrast, a thick, dark and dense summer–autumn layer alternates with a thin, light and porous winter–spring layer in any biannual lamina found in normal epigenic tufa that is controlled mainly by the change of temperature and CO2. The biannual lamination in the thermogene travertine was primarily controlled by changes in the dilution-dominated carbonate precipitation rate, the darker color of the warm-rainy-season layer being due to soil-derived clay and organic matter introduced by the overland flow. This study thus demonstrates that rates of carbonate precipitation and the formation of lamination in the travertine at Baishuitai were controlled chiefly by a climatic factor (rainfall), which has implications for using the fossil travertine at the site to reconstruct the climate in the past. Additionally, it shows that differences in rate-controlling mechanisms of carbonate precipitation must be considered when using epigenic tufa and endogenic travertine to reconstruct the paleoclimate and paleoenvironmental parameters (temperature + CO2 vs. rainfall).

Preparation and characterization of sol–gel derived UV-curable organo-silica–titania hybrid coatings

In this work, UV-curable organic–inorganic hybrid coatings based on cycloaliphatic epoxyacrylate were prepared by sol–gel technique. Acid catalyzed solutions of tetraethylorthosilane (TEOS) containing Ti:acac complex were used as an inorganic precursors. UV-curable, transparent hybrid coating materials were applied on plexiglass substrates and their coating performance was investigated by the analyses of various tests such as hardness, gloss, cross-cut adhesion tests, stress–strain test and optical transmission. The mechanical measurements showed that, the tensile properties of coatings underwent an abrupt change from a brittle to a tough material when the inorganic part was incorporated into the cycloaliphatic epoxy acrylate based organic network. UV–vis transmission spectroscopy results indicated that the hybrid materials with high titanium content have good transparences. The thermal behaviour of the coatings was also evaluated. It is observed that the thermal stability of the hybrids is enhanced with incorporation of sol–gel precursor.

Synthesis and characterization of UV-curable dual hybrid oligomers based on epoxy acrylate containing pendant alkoxysilane groups

This work involves the synthesis of novel hybrid oligomers based on a UV-curable epoxy acrylate resin (EA). The EA resin was modified with various amount of 3-isocyanatopropyl trimethoxysilane (IPTMS) coupling agent. The modification percentage of the hybrid oligomer was varied from 0 to 50 wt.%. UV-curable, hard and transparent organic–inorganic hybrid coatings were prepared on Plexiglas substrates and their characterization was performed by the analyses of various properties such as hardness, gloss, tape adhesion test and stress–strain test. Results from the mechanical measurements show that the properties of hybrid coatings improve with the increase in modification ratio. The thermal behavior of coatings was also evaluated. It is observed that the thermal stability of epoxy acrylate coatings is enhanced with incorporation of siloxane. Gas chromatography/mass spectrometry analyses showed that the initial weight loss obtained in thermogravimetric analysis is due to the degradation products of the photoinitator and the acrylic acid moiety of acrylic monomers.