Maximum Light Absorption Research Articles

Two-Channel Bioprotonic Photodetector.

Merging biological systems with electronic components requires converting biological ionic currents into electrical signals. Previously, we coupled green-light-activated transport of protons by a palladium-binding version of H. turkmenica deltarhodopsin (HtdR) with electronic signal generation by exploiting palladium hydride (PdHx) formation on palladium (Pd) electrodes. Here, webroaden the scope of these devices by showing that blue proteorhodopsin (BPR) from marine bacteria is a suitable proton pump for expanding their spectral range. After engineering BPR for Pd binding and high-level expression in E. coli and after demonstrating that the fused Pd-binding domain is properly oriented to bring exiting protons to the surface of Pd/PdHx contacts, we take advantage of the pH tunability of the BPR absorption spectrum to construct HtdR- and BPR-based devices with light absorption maxima, and thus photocurrent maxima, separated by 37 nm. These devices exhibit wavelength-dependent photocurrent production when illuminated between 450 and 600 nm, opening the door to the development of biological cameras.

Synthesis and properties of the compositе polyanylin–ferrocianide

Samples of polyaniline and polyaniline-ferricyanide composites were synthesized by the reaction of oxidation polycondensation of aniline. Ammonium peroxide disulfate (NH 4 ) 2 S 2 O 8 was used as an oxidizing agent in this reaction, which was performed in an acid medium (aniline + HCl) or (aniline + H 3 [Fe (CN) 6 ]). Structures of synthesized chemical compounds were studied by IR spectroscopy. Spectral analysis shows the presence of light absorption bands at 1 140 cm-1, which are due to oscillations of the group of atoms –N=Q–N + –B–, which is characteristic of the polaron state of the links of the polyaniline chain. The peak at 1450 cm -1 corresponds to deformation oscillations –N = Q = N groups of polyaniline, and the absorption band with a peak at 1600 cm -1 refers to the deformation oscillations of the N–H groups. An analysis of the results of an IR spectroscopic study suggests that the structure of the composite corresponds to the structure of the emeraldalin salt of polyaniline. The coloring of aqueous solutions of salts containing Cu 2+ ions indicates that they absorb light in the visible range of the spectrum. To determine the wavelength at which the maximum absorption of light is achieved by solution of CuSO 4 , the UV spectrophotometer of theCuSO 4 solutions in the visible region (500–900 nm) was measured with the concentration range 0.00625–0.2 M, from which the maximum was determined. The absorption of light by hydrated Cu 2+ ion accounts for a wavelength of 810 nm. All subsequent measurements of the optical density of the investigated solutions were performed at wavelengths 810 nm. A study was performed on adsorption of CuSO 4 from aqueous solutions on the surface of the polyaniline-ferrocyanide composite at 20 C. To measure adsorption, a method was used to determine the optical density of the solution above the adsorbent. An analysis of experimental data suggests that the polyaniline composite {PAn + H 3 [Fe (CN) 6 ]} is the best adsorbent for heavy metal ion Cu 2+ than the polyaniline itself, the amount of CuSO 4 adsorption on the polyaniline-ferocyanide composite is 0.007 mole/g adsorbent. The presence of a conjugated system in the structure of the polyaniline chain, the component of which are nitrogen atoms with 2 s electron vapor, makes it possible to form complexes of polyyaniline with metal ions, which have vacant electrons for the 3 d energy level. The ferrocyanide ion increases the charge density on polyaniline chains, thereby improving the ability of the composite to adsorb Cu(II) from the aqueous solution. The cyanide complex of the composite can take ions of metals from solutions through the coordination mechanism of the inner sphere, which determines the synergistic effect of the composite components (polyaniline chains and ferrocyanate adsorption centers). Keywords : polyaniline, polyaniline-ferricyanide composites, adsorption Cu 2+ .

Изучение комплексообразования меди(II) с 2,7-бис(азо-2-гидрокси-3-сульфо-5-нитробензол)- 1,8-дигидроксинафталин-3,6-дисульфонатриевой солью в присутствии третьих компонентов

This article presents a study on the complexation of copper (II) with 2,7-bis(azo-2-hydroxy-3-sulfo5-nitrobenzene)-1,8-dihydroxynaphthalene-3,6-disulphonosodium salt (R) in the presence of diphenylguanidine (DPG), triphenylguanidine (TPG) and non-ionic SAA Triton X-114 (TX-114), carried out by spectrophotometric method. The optimal conditions for the Cu-R complexation are established as follows: pH=3 with the maximum light absorption of the complex occurring at a wavelength of 538 nm. The yield of the Cu-R complex reaches a maximum at the R component concentration of 8·10 -3 M, while the highest value for Cu-R-DPG complex is observed at concentrations of 8·10 -5 and 1·10 -3 M for the R and DPG components, respectively. The maximum of Cu-R-TFG is noted with concentrations of the R and TPG components comprising 8·10 -5 and 8·10 -4 M, respectively. The maximum yield of the Cu-R-TritonX-114 complex was obtained at a component concentration of 8·10 -5 and 8·10 -4 M, respectively. All complexes are formed immediately following the mixing of the component solutions and differ in stability. In the presence of a third component, the maximum absorption is observed at a wavelength of 512 nm (pH=1), 491 nm (pH=2) and 572 nm (pH=2) for the Cu-R-TX-114, Cu-R-DPG and Cu-R-TPG complex, respectively. The reaction ratio of components in the composition of homogeneous (Cu:R =1:2) and mixed ligand (Cu:R:X= 1:2:2) compounds is established. The interval of obedience to Beer's law equal to 0.12–2.32 mg/mL was determined for Cu-R complexes. For Cu-R-TX-114, Cu-RDPG and Cu-R-TPG, the determined interval comprised 0.07–2.32 mg/mL. The following values of stability constant for the complexes was established using the spectrophotometric method: 8.75±0.05 (Cu-R), 9.59±0.05 (Cu-R-TX-114), 9.85±0.05 (Cu-R-DPG) and 9.92±0.04 (Cu-R-TPG). The molar absorption coefficient of the complexes was determined as equal to 10400 (Cu-R), 15000 (Cu-R-TX-114), 15500 (Cu-R-DPG) and 16000 (Cu-R-TPG). The logK hyd = 7.5, lgK hyd = 12.7 and lgK hyd = 13.9 constants of the nickel ion hydrolysis were obtained. The coefficients of the calibration curve equation are determined by the method of least squares. Under optimal complexation conditions, Cu-R was titrated with a component solution (TritonX-114, DPG and TPG) using the conductometric method. The effect of impurity ions and masking substances was studied. The determination of copper (II) is practically unhindered by alkaline, alkaline-earth and some transition elements, such as Ca (II), Ba (II), Mn (II), Cr (III), Sn (IV), Ga (III), In (III) and Zr (IV). The proposed express technique is characterised by its high sensitivity and selectivity, as well as being applicable for the determination of copper in food cereals.

Photocolorimetric determination of zirconium microcontent in the products of linear alpha-olefins production

Analytical control of the technological process of linear alpha-olefins (LAO) production using a zirconium carboxylate based catalyst according to α-SABLIN technology calls for determination of the residual zirconium in the solvent when washing equipment, in the reaction products and wastewater, the purity of which is strictly regulated. Features of photocolorimetric determination of zirconium impurities with different complexing agents are considered and sensitivity of the determination with iron, aluminum, nickel and chromium present is estimated by comparing the values of the «sensitivity index» (by E. Sendel) and «specific absorption» (by Z. Marchenko). The reaction of complex formation with arsenazo III in 9 – 10 M HCl is used for determination of zirconium in the LAO production related products. The resulting colored complex exhibits the maximum light absorption at a wavelength of 670 nm. The measured content ranges from 0.100 to 100 mg/kg, 103-fold amounts of Ni2+, Fe3+, Al3+ and 400-fold amounts of Cr3+ do not interfere with the determination. The method of additives is used to eliminate the interfering effect of the acidity of the medium. It is shown that the developed technique provides a satisfactory level of the reproducibility and correctness of the results for analytical control of LAO production.

Tailoring Metal and Insulator Contributions in Plasmonic Perfect Absorber Metasurfaces

Maximum absorption of light using plasmonic perfect absorbers (PPAs) is highly desired in the field of energy harvesting, sensing, as well as photothermal light sources. We reveal how optical properties of several popular metals (Au, Ag, Cu, Pd) and insulators (SiO2, Si, ZnO) affect performance of PPAs at mid-infrared (IR) wavelengths. At this wavelength range radiation properties of a plasmonic system are also linked to its thermal conductivity; hence, in this work thinner insulator layers around 10 nm in thickness are given special focus. Optical properties of experimentally prepared (by plasma sputtering) structures follow expected scalings; however, departure from the finite-difference time-domain (FDTD) simulations is significant when roughness of the first metal base layer is not taken into account. Electrical conductivity is shown to strongly affect performance of PPAs. Absorbance values above 90% were attained for nanodisc array based PPA structures with a 10 nm thick insulator spacer.

Dynamical resonance shift and unification of resonances in short-pulse laser-cluster interaction

Pronounced maximum absorption of laser light irradiating a rare-gas or metal cluster is widely expected during the linear resonance (LR) when Mie-plasma wavelength $\lambdaM$ of electrons equals the laser wavelength $\lambda$. On the contrary, by performing molecular dynamics (MD) simulations of an argon cluster irradiated by short 5-fs (fwhm) laser pulses it is revealed that, for a given laser pulse energy and a cluster, at each peak intensity there exists a $\lambda$ -- shifted from the expected $\lambdaM$ -- that corresponds to a {\em unified dynamical} LR at which evolution of the cluster happens through very effective unification of possible resonances in various stages, including (i) the LR in the initial time of plasma creation, (ii) the LR in the Coulomb expanding phase in the later time and (iii) anharmonic resonance in the marginally over-dense regime for a relatively longer pulse duration, leading to maximum laser absorption accompanied by maximum removal of electrons from cluster and also maximum allowed average charge states for the argon cluster. Increasing the laser intensity, the absorption maxima is found to shift to a higher wavelength in the band of $\lambda\approx (1-1.5)\lambdaM$ than permanently staying at the expected $\lambdaM$. A naive rigid sphere model also corroborates the wavelength shift of the absorption peak as found in MD and un-equivocally proves that maximum laser absorption in a cluster happens at a shifted $\lambda$ in the marginally over-dense regime of $\lambda\approx (1-1.5)\lambdaM$ in stead of $\lambdaM$ of LR. Present study may find importance for guiding an optimal condition laser-cluster interaction experiment in the short pulse regime.

Nanocavity induced light concentration for energy efficient heat assisted magnetic recording media

Enhancing light absorption in the recording media layer can improve the energy efficiency and prolong the device lifetime in heat assisted magnetic recording (HAMR). In this work, we report the design and implementation of a resonant nanocavity structure to enhance the light-matter interaction within an ultrathin FePt layer. In a Ag/SiO2/FePt trilayer structure, the thickness of the dielectric SiO2 layer is systematically tuned to reach maximum light absorption at the wavelength of 830 nm. In the optimized structure, the light reflection is reduced by more than 50%. This results in effective laser heating of the FePt layer, as imaged by an infrared camera. The scheme is highly scalable for thinner FePt layers and shorter wavelengths to be used in future HAMR technologies.

Optimal-Enhanced Solar Cell Ultra-thinning with Broadband Nanophotonic Light Capture

SummaryRecent trends in photovoltaics demand ever-thin solar cells to allow deployment in consumer-oriented products requiring low-cost and mechanically flexible devices. For this, nanophotonic elements in the wave-optics regime are highly promising, as they capture and trap light in the cells' absorber, enabling its thickness reduction while improving its efficiency. Here, novel wavelength-sized photonic structures were computationally optimized toward maximum broadband light absorption. Thin-film silicon cells were the test bed to determine the best performing parameters and study their optical effects. Pronounced photocurrent enhancements, up to 37%, 27%, and 48%, respectively, in ultra-thin (100- and 300-nm-thick) amorphous, and thin (1.5-μm) crystalline silicon cells are demonstrated with honeycomb arrays of semi-spheroidal dome or void-like elements patterned on the cells' front. Also importantly, key advantages in the electrical performance are anticipated, since the photonic nano/micro-nanostructures do not increase the cell roughness, therefore not contributing to recombination, which is a crucial drawback in state-of-the-art light-trapping approaches.

CONCENTRATION OF THORIUM (IV) BY CHELATING SORBENT

The paper analyses complexation of thorium(IV) with 2,3,4-trihydroxy-4’-fluoroazobenzene. A complex is formed immediately after mixing the components. Their molar ratio (1:2) was established using the methods of Starik–Barbanel relative yield, equilibrium shift and isomolar series. The maximum light absorption of the complex is observed at 440 nm, with the molar absorption coefficient being equal to 1.80×10 4 . In this work, we synthesised a new sorbent containing fragments of para-aminosalicylic acid. Identification of sorbents was carried out using IR spectroscopy. Sorption was studied in static and dynamic modes. The optimal conditions for concentration were investigated. The magnitude of the sorption and the degree of metal extraction was calculated from its residual concentration in the solution using a spectrophotometric method. Our results show that the maximum sorption is observed at pH = 4. In the course of preliminary kinetic experiments, it was found that the maximum sorption of cadmium is attained within 2 hours, remaining practically at the same level thereafter. The effect of the ionic strength of the solution was studied using the photometric method. Thorium(IV) was sorbed from solutions having an ionic strength of 0.1–1.4. It is shown that a significant decrease in the sorption of thorium(IV) occurs in solutions with an ionic strength of more than 0.2 M. The effect of metal concentration on sorption was also investigated. An isotherm of thorium sorption by the synthesised sorbent was constructed. An increased concentration of thorium(IV) in the solution leads to an increase in the amount of sorbed metal, with the maximum concentration being reached at 1856 mg/l. We also studied the effect of various acids (HClО 4 , H2SО 4 , HNО 3 , HCl) on the desorption of thorium(IV) from the sorbent: thorium(IV) was quantitatively desorbed by 2 M nitric acid. The degree of extraction of thorium ions (IV) under optimal conditions exceeds 95%. The study has revealed the possibility of using the matrix of a copolymer of maleic anhydride and styrene modified by para-aminosalicylic acid for sorption-photometric determination of thorium(IV). Following regeneration, this sorbent can be reused.

Natural Random Nanotexturing of the Au Interface for Light Backscattering Enhanced Performance in Perovskite Solar Cells

As the efficiency of a solar cell approaches its limits, photonic considerations to further enhance its performance overtake electronic ones. It has been theoretically shown for GaAs solar cells that with the combined effects of a surface random texturing and a perfectly reflecting rear mirror, efficiencies close to the Shockley–Queisser limit can be reached, even when the absorber layer is very thin. In here, we demonstrate a method for taking advantage of surface random texturing to enhance the efficiency of planar perovskite solar cells. By naturally transferring the perovskite random nanotexturing to the back semiconductor/metal interface, where the contrast in the imaginary part of the refractive index is very large, backscattering reduces light escape from the solar cell structure. This leads to a close to optimal light absorption that allows bringing the cell efficiency from 19.3% to 19.8%. Such a path we opened toward an ergodic behavior for maximum light absorption in perovskite cells may lead to...

Influence of mineral substances on the synthesis of volatile organic compounds by Pleurotus ostreatus in the process of solid phase cultivation

Mineral substances play an important role in ensuring high-grade growth and high organoleptic quality of the fruit bodies of basidiomycetes. In the process of solid-phase cultivation of the mushroom Pleurotus ostreatus (Jacq.: Fr.) Kumm. the lignocellulosic substrates were enriched with mineral additives of calcium, iron and selenium. Their influence on the synthesis of volatile aroma compounds was investigated by the methods of sensory profile analysis and ultraviolet spectroscopy. Mineral additives in the form of CaCl2, FeSO2•7H2O and Na2SeO3 salts were added to the substrate (sunflower husk, barley straw) before sterilization in concentrations that correspond to the physiological needs of the mushrooms. When carrying out a sensory profile analysis of dried fruit bodies, the following attributes of the flavor were determined: mushroom, woody, sweet, herbaceous, fish, meat, floral, earthy, acidic, putrescent. The conducted profile analysis showed an unequal dependence of the effect of mineral additives for each of the P. ostreatus strains. For IBK-549 and IBK-1535, an increase in the intensity of mushroom notes of aroma was observed with the addition of calcium and selenium to the husks, and for IBK-551, this was observed with the addition of iron and selenium to both substrates. The volatile aroma compounds were extracted with hexane at boiling point for 30 minutes. Absorption spectra were recorded in the wavelength range 200–330 nm. The examined extracts had light absorption maxima at 200–210 and 260–300 nm, which is typical for solutions of unsaturated compounds that have non-conjugated double bonds, saturated and unsaturated aldehydes and ketones. Additions of iron to the substrates increased the intensity of light absorption in comparison with the control. Additions of selenium selectively influenced different strains, and calcium ions did not significantly affect the change in the intensity of light absorption, and therefore the synthesis of volatile compounds by mushrooms. The level of synthesis of aroma-forming substances was higher when cultivating fungi on sunflower husks than on barley straw. This was confirmed both by the obtained aroma profiles and by the recorded absorption spectra of all examined strains. The study showed the possibility of influencing the organoleptic qualities of P. ostreatus fruiting bodies during solid-phase cultivation by supplementing the composition of lignocellulosic substrates with various mineral additives.

Comparative Analysis of Low-Resolution Microwave Spectra of Monobasic Alcohols

Additive modeling of low-resolution (LR) microwave spectra using high-resolution spectra was employed for calculating the frequencies of the LR spectra for trans- and gauche-conformations of ethanol (CH3CH2OH) and the trans-conformation of deuterolabeled 2propanol ((CD3)2CDOH) in the 0–2 THz range. The regions were found for the frequencies of the LR spectra, in which light absorption by these two molecules is greatest: 660–680 and 1120–1160 GHz for the gauche- and trans-conformation of ethanol and 480–500 GHz for the trans-conformation of deuterolabeled 2propanol. A comparative analysis was carried out for the spectral regions featuring maximum light absorption by ethanol, 1propanol, 2propanol, and deuterolabeled 2propanol. It was concluded that in going to heavier compounds, the LR spectral maxima are shifted toward lower frequencies. This shift is useful for the spectral identification of these molecules in environmental monitoring and production quality control.

Development of the methods for atomoxetine identification suitable for the chemical and toxicological analysis

The cases of acute and lethal poisonings by atomoxetine, an antidepressant, have been registered. Therefore, development of the available and reliable methods for its chemical and toxicological analysis is the topical issue.Aim. To develop the conditions for atomoxetine detection in the presence of a number of its pharmacological and structural analogs when performing the general TLC-screening and identification of the antidepressant by UV spectrophotometry.Materials and methods. Chromatographic mobility of antidepressants in thin sorbent layers was studied in 11 mobile phases, including those recommended by TIAFT, using five types of chromatographic plates. A number of chromogenic reagents was used for visualization. The UV-spectrum of atomoxetine was studied in 0.1 Mol • L-1 solution of hydrochloric acid.Results and discussion. Chromatographic systems with the low correlation of Rf values for atomoxetine that make them suitable for the general TLC-screening have been found. The UV spectrum of atomoxetine in the acid solution had light absorption maxima at wavelengths of 270 (e = 1300; A11 = 45) and 277 nm.Conclusions. A combined use of three mobile phases: methanol – 25 % ammonia solution (100 : 1.5), cyclohexane – toluene – diethylamine (75 : 15 : 10), and toluene – acetone – 25 % ammonia solution (45 : 45 : 7.5 : 2.5) provides a reliable atomoxetine detection in the presence of a number of its pharmacological and structural analogs when performing the general TLC-screening. The presence of specific light absorption in the UV region of the spectrum for atomoxetine makes the UV spectrophotometry method suitable for identification of the antidepressant in toxicological studies.metry method suitable for identification of the antidepressant in toxicological studies.

Spectrophotometric and theoretical studies of the protonation of Allura Red AC and Ponceau 4R

The acid-base properties of Allura Red AC and Ponceau 4R azo dyes were investigated by spectrophotometric, potentiometric and tristimulus colourimetry methods. Ionization constants of the functional groups were also found in aqueous solutions of the dyes. It was discovered that the wavelength of the maximum light absorption of Allura Red AC and Ponceau 4R solutions does not change significantly over a wide pH range. As a result, spectrophotometric methods yield little information for assessing the acid-base properties of the dyes. It was shown with a help of the tristimulus colourimetry method that it is possible to determine the ionization constants of the functional groups of the dyes even when there is significant overlap of the absorption bands of the acid-base forms. The basic spectrophotometric characteristics of the main forms of Allura Red AC and Ponceau 4R in water and organic solvents were calculated. The molar absorbance coefficients of azo forms were shown to increase as the dielectric permittivity of the solvent increases. It was determined that in aqueous solution the dyes exist in the azo form over a wide range of acidity – pH 2–12 for Allura Red AC (λmax = 505 nm; ελ = 3.1·104 dm3 mol−1 cm−1) and 1–13 for Ponceau 4R (λmax = 510 nm; ελ = 1.7·10−4 dm3 mol−1 cm−1). The most probable protonation/deprotonation schemes were theoretically determined for Allura Red AC and Ponceau 4R using DFT calculations.

The Synthesis and Characterization of Ag/Ag2O/TiO2/NGP Composites as Adsorbents and Photocatalysts for Wastewater Removal

An Ag/Ag2O/TiO2/NGP with different nanographene platelets (NGP) weight percents was synthesized using the hydrothermal method. The NGP weight percent was 5, 10, and 15 weight percent, respectively. The structural properties of the samples were characterized by X-ray diffraction. The optical properties of the samples were investigated by UV-Vis spectroscopy and their thermal properties were investigated by Thermo Gravimetric Analysis and Differential Thermal Analysis. The existence of a cubic structure from Ag and Ag2O, an anatase from TiO2, and a graphitic like structure from NGP indicated that the samples were successfully formed. The maximum light absorption at 435 nm indicated the existence of surface plasmon resonance (SPR) from silver nanoparticles. The phase transformation of Ag2O to Ag occurred at 435 °C. Adsorption and the photocatalytic performance were investigated in the degradation of methylene blue from the aqueous solution. The adsorption ability of Ag/Ag2O/TiO2/NGP composites increased by increasing the NGP weight percent. The adsorption process of MB followed pseudo-second-order kinetic reactions. The photocatalytic activity of Ag/Ag2O/TiO2/NGP showed that Ag/Ag2O/TiO2/NGP with a 10 weight percent NGP exhibited the highest photocatalytic performance, with a removal ability of approximately 96 percent.

A unique choanoflagellate enzyme rhodopsin exhibits light-dependent cyclic nucleotide phosphodiesterase activity

Photoactivated adenylyl cyclase (PAC) and guanylyl cyclase rhodopsin increase the concentrations of intracellular cyclic nucleotides upon illumination, serving as promising second-generation tools in optogenetics. To broaden the arsenal of such tools, it is desirable to have light-activatable enzymes that can decrease cyclic nucleotide concentrations in cells. Here, we report on an unusual microbial rhodopsin that may be able to meet the demand. It is found in the choanoflagellate Salpingoeca rosetta and contains a C-terminal cyclic nucleotide phosphodiesterase (PDE) domain. We examined the enzymatic activity of the protein (named Rh-PDE) both in HEK293 membranes and whole cells. Although Rh-PDE was constitutively active in the dark, illumination increased its hydrolytic activity 1.4-fold toward cGMP and 1.6-fold toward cAMP, as measured in isolated crude membranes. Purified full-length Rh-PDE displayed maximal light absorption at 492 nm and formed the M intermediate with the deprotonated Schiff base upon illumination. The M state decayed to the parent spectral state in 7 s, producing long-lasting activation of the enzyme domain with increased activity. We discuss a possible mechanism of the Rh-PDE activation by light. Furthermore, Rh-PDE decreased cAMP concentration in HEK293 cells in a light-dependent manner and could do so repeatedly without losing activity. Thus, Rh-PDE may hold promise as a potential optogenetic tool for light control of intracellular cyclic nucleotides (e.g. to study cyclic nucleotide-associated signal transduction cascades).

Low temperature hydrothermal synthesis of SrTiO3 nanoparticles without alkali and their effective photocatalytic activity

SrTiO3 nanoparticle (NP) photocatalyst was synthesized with a facile and environmentalfriendly hydrothermal method using tetrabutyltitanate, strontium oxide, and ethanolamine as precursors at low temperature without alkali as mineralizer for the first time. The SrTiO3 nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and N2 Brunauer–Emmett–Teller (BET) method. The SrTiO3 catalyst synthesized at 120 °C (STO-120) exhibited the highest photocurrent intensity among the samples synthesized at different hydrothermal temperatures. The high photocatalytic performance of STO-120 was mainly attributed to the more homogeneous and minimum nanoparticle size, the highest surface area, and the maximum light absorption property among the four different samples. This work presented an applicable and facile method to fabricate a highly active and stable SrTiO3 photocatalyst for organic pollutant degradation.

Modeling of optimum light absorption in random plasmonic solar cell using effective medium theory

Random plasmonic nanostructures are very suitable candidates for light trapping in thin film solar cells because of their ability of efficient transportation and localization of light in a broad spectrum. In this work, besides the introducing of a novel structure of plasmonic thin-film solar cell, in which metal nanoparticles are randomly distributed through the photoactive layer of solar cell, we are presenting a new simple calculation method which can predict the behavior of plasmonic solar cells.To avoid the difficulty of analytical calculation and due to small size of constituents of the structure, we have used the effective medium theory to describe its optical properties. We have used a general description of effective dielectric function that can support each effective medium theory named spectral density theory, which takes into account the percolation of metal component and also interaction among inclusions. Using this method, the optimum values of nanoparticle's filling fraction for each wavelength within the active layer can be found where the solar cell can have the maximum absorption of light, thereupon the optimum external quantum efficiency.

Osmolarity and spectrophotometric property of brilliant blue green define the degree of toxicity on retinal pigment epithelial cells exposed to surgical endoilluminator.

ObjectiveTo evaluate the effect of varying concentrations of brilliant blue green (BBG) and their different biochemical characteristics on retinal pigment epithelial (RPE) cells under xenon light source illumination at varying distances to identify safe parameters for intraoperative use.MethodsHuman retinal RPE cells (ARPE-19) were exposed to two concentrations (0.25 and 0.50 mg/mL) of BBG and illuminated with a xenon surgical illuminator at varying distances (10 and 25 mm), intensity levels, and time intervals (1, 5, and 15 minutes). Additionally, the effect of osmolarity was examined by diluting BBG in different concentrations of glucose. Cytotoxicity of BBG and osmolarity effects on cell viability were evaluated using a WST-1 assay. Light absorption and emission characteristic of BBG in different solvents were measured using a plate reader at different wavelengths. Lastly, the activity of caspase-3 was also studied.ResultsCell viability of ARPE-19 cells was 77.4%±12.7%, 78.7%±17.0%, and 65.0%±19.7% at 1, 5, and 15 minutes to exposure of high illumination xenon light at 10 mm (P<0.05) compared to controls. At both distances of illumination (10 and 25 mm), similar cell viabilities were seen between 1 and 5 minutes of exposure. However, there was a decline in viability when the illumination was carried out to 15 minutes in all groups (P<0.05). There was no significant reduction in cell viability in presence or absence of xenon light in different osmolar solutions concentrations of glucose (P>0.05). Maximal light absorption of BBG was noted between 540 and 680 nm. Activated caspase-3 level was not significant in both the concentrations of BBG (P>0.05).ConclusionOur findings suggest that BBG at 0.25 mg/mL during vitreoretinal surgery is safe and not toxic to RPE cells up to 5 minutes under focal high illumination (10 mm) and up to 15 minutes under medium diffuse illumination (25 mm). BBG was safe to be mixed with isotonic glucose solution at the concentration range of 2.5%–10%, regardless of the illumination status.

Azo-Substitute of EthoxyAcridine – A New Reagent for Extraction-Photometric Determination of Tellurium (IV)

We studied associates of halogen telluride (Cl, Br) with 9-amine-4-ethoxyacridine-6-azo-N-N′-diethylaniline (AEADEA) by spectrophotometric method. It was established that associates are extracted well with chloroform-acetone (3:2). We determined the compositions, physical and chemical and analytical properties of complexes (εk, βKD, D, R%). Maximum light absorption for chloride complexes is found to be λmax 520 nm, but for bromide complexes - λmax 530 nm. For establishing the composition of azo- substitute ofethoxyacridine the synthesized reagents were exposed to elemental analysis, as well titanometrictitration by azo group. We developed new extraction-photometric determination methods of tellurium. Lambert-Beer law is observed in the range 0.5-15 mkgTe at 5 ml medium.