UV Irradiation Conditions Research Articles

A hollow mesoporous silica and poly(diacetone acrylamide) composite with sustained-release and adhesion properties

Controlled release formulation of pesticides is a highly desirable way to increase the efficiency of the pesticide as well as help reduce environmental pollution issues. In the present study, a novel adhesive organic-inorganic hybrid material with a uniform size and morphology was fabricated employing hollow mesoporous silica (HMS) as an inlayer material and poly(diacetone acrylamide) (PDAAM) as an outer layer material. HMS was fabricated using polystyrene (PS) spheres as a hard template. Then, HMS was functionalized with 3-aminopropyltriethoxysilane and 2-bromoisobutyryl bromide after removal of PS. Finally, PDAAM was grafted onto HMS using surface-initiated atom transfer radical polymerization. Cyantraniliprole (CNAP) utilized as a model pesticide was incorporated into hybrid material to prepare controlled release formulation. The results showed that both CNAP−loaded HMS and HMS−PDAAM had extraordinary loading efficiencies (approximately 50% w/w). Kinetic studies of CNAP release demonstrated that CNAP−loaded HMS−PDAAM exhibited a sustained release property for at least 25 days. The stability test identified that CNAP−loaded HMS and HMS−PDAAM were much more stable under UV irradiation and thermal conditions than CNAP technical. Tests of the adhesive properties showed that the adhesive property of HMS−PDAAM was far stronger than that of HMS on rice leaves. Given the advantages of HMS−PDAAM, this hybrid material may be applied to other photosensitive pesticides, especially those used for foliar spraying.

Seawater-temperature and UV-radiation interaction modifies oxygen consumption, digestive process and growth of an intertidal fish

UV-radiation (UVR) and temperatures have increased substantially over recent decades in many regions of the world. Both stressors independently have shown to affect the metabolism and growth in fish. However, because increase of both stressors are occurring concomitantly, to better understand their influences on marine species, their combined effects were evaluated. We test the hypothesis that UVR and temperature act synergistically affecting the metabolism, digestive process and growth of an intertidal fish. Two UVR conditions (with and without UVR) and two temperature levels (20° C and 25° C) were used. UVR increase the oxygen consumption and this was associated to opaque feces production. The absorption efficiency was higher without UVR at high temperatures (25 °C) and with UVR at low temperatures (20 °C). Finally, independent of UVR treatment, fish subjected to low temperature have higher biomass than those of high temperature. The interaction between UVR and temperature may influence on the physiology and growth of animals that inhabit in extreme habitats as upper intertidal, it could pose significant functional for aquatic animal survivorship.

Resource versus consumer regulation of phytoplankton: testing the role of UVR in a Southern and Northern hemisphere lake

Models predict that phytoplankton is bottom-up regulated by resources and top-down controlled by consumers. However, how the strength of these controls varies with UV radiation (UVR) is not well known. In this study, we test the hypothesis that the phosphorus (P) content of phytoplankton affects the role that UVR exerts strengthening or weakening the resource and consumer control on distinct stoichiometric and functional phytoplankton traits. To accomplish this, we coupled field meso- and microcosms in a split-plot design using UVR treatments at the plot level and nutrients and zooplankton (presence/absence) at the subplot level, in two mountain lakes characterized by their P-sufficient (La Caldera) and P-deficient phytoplankton (Los Cantaros). We found that the addition of nutrients decreased phytoplankton C:P in both lakes, but enhanced primary production and chlorophyll a only under UVR in La Caldera. Also, the effects of zooplankton on phytoplankton varied between lakes and UVR conditions, and increased primary production and chlorophyll a under UVR in La Caldera, but not in Los Cantaros. These results suggest that differences in the stoichiometric aspects associated with the P content in phytoplankton play a key role in how UVR affects resource and consumer controls, with much weaker effects in P-deficient food webs.

Photocatalysis effect of a novel green synthesis gadolinium doped titanium dioxide nanoparticles on their biological activities

Abstract We report the synthesis of gadolinium doped titanium dioxide (GdT) nanoparticles (NPs) via hydrothermal method using a novel bioreductant Piper betel leaf. The physiochemical properties of green synthesized GdT NPs were characterized using various techniques. The results reveal that GdT NPs have attached with the biomolecules which were supporting evidence for the reduction and capping agents. GdT NPs have crystalline in nature and their estimated grain size is of about 5.45 nm by the Scherer’s formula. GdT NPs consist of well-dispersed agglomerates of grains with a narrow size distribution of about 4 nm to 7 nm and are having spherical in nature. GdT NPs are thermally stable. In addition, GdT NPs were subjected to antimicrobial and antioxidant assays. Herein, we observed that the GdT NPs show higher antibacterial activities against Staphylococcus aureus as compared with Escherichia coli and the minimum inhibitory concentration (MIC) value was found to be 25 μg mL−1 under UV irradiation condition for both the cases. Furthermore, antioxidant activities of GdT NPs were evaluated in vitro, using the 1, 1- diphenyl-2-picrylhydrazyl (DPPH) radical cation decolorization test. Results suggest that GdT NPs give promising antioxidant activity as compared to standard ascorbic acid and Piper betel leaf. This novel and efficient strategy will show the route for avoiding the use of toxic solvents and a promising green route to restrict for drug discovery from natural products. Thus, the present findings may shine in the field of green pharmaceuticals industries.

83‐3L: Late‐News Paper: A Novel High Reactive and High Reliable Monomer for Polymer‐Sustained Alignment Liquid Crystal Displays

The Polymer Sustained Alignment (PSA) technology is widely used for Liquid Crystal Display (LCD) TV application etc., because of its high transmittance, high contrast ratio and fast response. In this study, we have developed a novel high reactive and high reliable monomer for PSA. Also we found UV irradiation condition had a huge impact on Image Sticking issue, we propose the optimal UV condition for our new monomer too.

Stopband tuning of TiO2 inverse opals for slow photon absorption

The effect of photonic photocatalysis was explored employing TiO2 inverse opal structures. The degradation of methylene blue in aqueous phase was performed under visible light (λ=450nm) irradiation and showed an improved degradation rate over TiO2 inverse opals with respect to non-structured films. Moreover, tuning the stopband by means of varying the lattice parameter and the irradiation incident angle results in a further improvement of the photocatalytic rate due to the slow photon effect. The gas-phase photocatalytic degradation of acetaldehyde under UV irradiation and ISO-standard conditions showed a similar (0.6%) photonic efficiency in all the studied TiO2 inverse opals regardless the photonic lattice parameter. Gas phase degradations were useful to investigate diffusional properties, in particular for small pore size samples. The mechanical stability of the samples, impacting directly on the structure-dependent photocatalytic performance, was also studied as a function of the consecutive photocatalytic reaction cycles.

Photostability of plasma polymerized \u03b3-terpinene thin films for encapsulation of OPV

Optically transparent, smooth, defect-free, chemically inert and with good adhesion to a variety of substrates, plasma polymers from plant-derived secondary metabolites have been identified as promising encapsulating materials for organic electronics and photovoltaics. Here, we demonstrate that an encapsulating layer of plasma polymerized γ-terpinene reduces degradation-related loss in conversion efficiency in PCPDTBT:PC70BM solar cells under ambient operating conditions. The stability of γ-terpinene films was then investigated under extreme UV irradiation conditions as a function of deposition power. When exposed to ambient air, prolonged exposure to UV–A and UV–B light led to notable ageing of the polymer. Photooxidation was identified as the main mechanism of degradation, confirmed by significantly slower ageing when oxygen was restricted through the use of a quartz cover. Under unnatural high-energy UV–C irradiation, significant photochemical degradation and oxidation occurred even in an oxygen-poor environment.

Changes in Meteorological Parameters (i.e. UV and Solar Radiation, Air Temperature, Humidity and Wind Condition) during the Partial Solar Eclipse of 9 March 2016

Solar eclipse is a spectacular phenomenon, which occurs when the position of the moon is between the sun and the earth. This phenomenon affects to the meteorological parameters, such as solar radiation, temperature, and humidity. The purpose of this study was to evaluate the impact of partial solar eclipse of 9 March 2016 to the change of several meteorological parameters. In the experimental procedure, we used automatic weather station (AWS) in one of building in Universitas Pendidikan Indonesia in Bandung. Bandung was selected because this place experienced partial (88.89%) solar eclipse on 9 March 2016. The result showed that compared to normal day, meteorological parameters changed during the solar eclipse, such as decreases in the UV and solar radiation, increases in relative humidity, and changes in air temperature and wind condition.

Electro-Optical Property in Hybrid Aligned Reverse mode Cell Using Liquid Crystals with Positive and Negative Dielectric Constant Anisotropies

We have proposed polymer stabilized liquid crystal (LC) cells with a hybrid alignment nematic (HAN) LC. LCs with positive and negative dielectric constant anisotropies are used. The cell has a reverse mode electro-optical property which shows a transparent state in a voltage off-state and a light scattering state in the on-state. We fabricate cells by irradiating the cell with a UV light from a planar alignment side or vertical alignment side in a polymerization process. The photopolymerization-induced segregation of the polymer from the LC and the influence of UV absorption by the LC bulk are investigated. A relationship between UV irradiation conditions and electro-optical characteristics in the cell is clarified. The light scattering intensity depends on an incident angle of light in the on-state, which is promising for application to smart windows. The feasibility of this concept is demonstrated with consideration of LC materials.

A study of ofloxacin and levofloxacin photostability in aqueous solutions

Introduction. The photostability is one of the most important properties of drugs. A comprehensive study of ofloxacin (OFX) and levofloxacin (LVX) photostability in aqueous solutions was performed. Ofloxacin is a chemotherapeutic agent belonging to the second generation fluoroquinolones and is a racemate of (R)-(+)-ofloxacin and (S)-(-)-ofloxacin (LVX).Material and Methods. Samples of OFX and LVX were subjected to stress conditions of UV irradiation using a mercury‑vapor lamp. The study involved development of enantioselective high‑performance liquid chromatography (HPLC) and high‑performance capillary electrophoresis (HPCE) methods for separation of OFX enantiomers and their degradation products. These methods were used to monitor the degradation process of OFX and LVX under irradiation and to determine the kinetics of degradation of these antibacterial agents. Moreover, the identification of photoproducts was also attempted. The structure of the main photoproducts was examined by mass spectrometry (MS).Results and Conclusions. Using HPLC method it was possible to observe two products of OFX degradation and only one for LVX, while using HPCE method eight products of OFX degradation and six of LVX were observed. Some of the photoproducts retain character of optically active compounds. The trend of the photodegradation of both tested compounds was described by autocatalytic reaction proceeding according to the Prout‑Tompkins model. Some of the products of the decomposition catalyze this reaction. The rate of degradation was similar for both enantiomers but t0.5 was slightly longer for LVX than OFX. Based on MS experiments the photodegradation products of the studied fluoroquinolones and possible pathways of UV induced decay were identified.

A study of ofloxacin and levofloxacin photostability in aqueous solutions

Introduction. The photostability is one of the most important properties of drugs. A comprehensive study of ofloxacin (OFX) and levofloxacin (LVX) photostability in aqueous solutions was performed. Ofloxacin is a chemotherapeutic agent belonging to the second generation fluoroquinolones and is a racemate of (R)-(+)-ofloxacin and (S)-(-)-ofloxacin (LVX).Material and Methods. Samples of OFX and LVX were subjected to stress conditions of UV irradiation using a mercury-vapor lamp. The study involved development of enantioselective high-performance liquid chromatography (HPLC) and high-performance capillary electrophoresis (HPCE) methods for separation of OFX enantiomers and their degradation products. These methods were used to monitor the degradation process of OFX and LVX under irradiation and to determine the kinetics of degradation of these antibacterial agents. Moreover, the identification of photoproducts was also attempted. The structure of the main photoproducts was examined by mass spectrometry (MS).Results and Conclusions. Using HPLC method it was possible to observe two products of OFX degradation and only one for LVX, while using HPCE method eight products of OFX degradation and six of LVX were observed. Some of the photoproducts retain character of optically active compounds. The trend of the photodegradation of both tested compounds was described by autocatalytic reaction proceeding according to the Prout-Tompkins model. Some of the products of the decomposition catalyze this reaction. The rate of degradation was similar for both enantiomers but t0.5 was slightly longer for LVX than OFX. Based on MS experiments the photodegradation products of the studied fluoroquinolones and possible pathways of UV induced decay were identified.

Heterogeneous Interaction of Isopropanol with Natural Gobi Dust.

The adsorption of isopropanol on Gobi dust was investigated in the temperature (T) and relative humidity (RH) ranges of 273-348 K and <0.01-70%, respectively, using zero air as bath gas. The kinetic measurements were performed using a novel experimental setup combining Fourier-Transform InfraRed spectroscopy (FTIR) and selected-ion flow-tube mass spectrometry (SIFT-MS) for gas-phase monitoring. The initial uptake coefficient, γ0, of isopropanol was measured as a function of several parameters (concentration, temperature, relative humidity, dust mass). γ0 was found independent of temperature while it was inversely dependent on relative humidity according to the empirical expression: γ0 = 5.37 × 10-7/(0.77+RH0.6). Furthermore, the adsorption isotherms of isopropanol were determined and the results were simulated with the Langmuir adsorption model to obtain the partitioning constant, KLin, as a function of temperature and relative humidity according to the expressions: KLin = (1.1 ± 0.3) × 10-2 exp [(1764 ± 132)/T] and KLin = 15.75/(3.21+RH1.77). Beside the kinetics, a detailed product study was conducted under UV irradiation conditions (350-420 nm) in a photochemical reactor. Acetone, formaldehyde, acetic acid, acetaldehyde, carbon dioxide, and water were identified as gas-phase products. Besides, the surface products were extracted and analyzed employing HPLC; Hydroxyacetone, formaldehyde, acetaldehyde, acetone, and methylglyoxal were identified as surface products while the formation of several other compounds were observed but were not identified. Moreover, the photoactivation of the surface was verified employing diffuse reflectance infrared fourier transform spectroscopy (DRIFTs).

Antimicrobial polymers: Antibacterial efficacy of silicone rubber–titanium dioxide composites

Control and reduction of microorganism infections in high-risk environments is up to date a challenge. Traditional techniques imply several limitations including development of antibiotics resistance and ecotoxicity. Then, polymers functionalized with photocatalyts arise as a promising solution against a broad spectrum of microorganisms found at, e.g. sanitary, food, and medical environments. Here, we present silicone rubber–TiO2 composites as novel antibacterial polymers. Four different types of composites with different TiO2 contents were produced and analyzed under UV irradiation and dark conditions in terms of particle distribution, chemical composition, photocatalytic activity, wettability, and antibacterial efficacy against Escherichia coli. Under UV irradiation, antibacterial sensitivity assay showed a 1000 times reduction of colony forming units after 2 h of light exposure so that the antibacterial ability of silicone–TiO2 composites was proved. Photocatalytic activity assessment suggested that reactive oxygen species induced by photocatalytic reaction at TiO2 particles are the main cause of the observed antibacterial effect. Scanning electron microscopy indicated no topographical damage after UV exposure. In addition, chemical analysis through Raman and X-Ray photoelectron spectroscopies demonstrated the stability of the silicone matrix under UV irradiation. Hence, the current work presents silicone–TiO2 composites as stable nonspecific antibacterial polymers for prevention of infections at multiple high-risk environments.

The role of Fe(III) on phosphate released during the photo-decomposition of organic phosphorus in deionized and natural waters

The photo-decomposition of organic phosphorus is an important route for the phosphorus cycle by which phosphate is regenerated in the aquatic environment. In this study, the role of Fe3+ as a natural photosensitizer toward the decomposition of organic phosphorus to release phosphate was examined in deionized and natural waters under UV and sunlight irradiation using glyphosate as the organic phosphorus model. The results showed that the concentration of glyphosate decreased with irradiation time in the Fe3+/UV and Fe3+/sunlight systems and TOC gradually decreased, which confirmed that glyphosate was degraded by Fe3+. The amount of phosphate released from the photo-decomposition of glyphosate was higher in the presence of Fe3+ than that of the control experiment under UV and sunlight irradiation conditions, and the generation rate of phosphate also increased with increasing Fe3+concentrations. The formation of hydroxyl radicals (·OH) in the Fe3+/UV and Fe3+/sunlight systems was identified according to the photoluminescence spectra (PL) using coumarin as the trapping molecule, and the steady-state concentrations of ·OH for the Fe3+/UV and Fe3+/sunlight systems were 1.06 × 10−14 M and 0.09 × 10−14 M, respectively. When natural water was spiked with glyphosate and Fe3+, the phosphate that was released in the Fe3+ was higher than that of the control, and the phosphate that was released was inhibited when isopropanol was added to the reaction. All of these results demonstrate that the photochemical activity of Fe3+ has significantly impact in the release of phosphate from the photo-decomposition of organic phosphorus.

Micro-mesoporous anatase TiO2 nanorods with high specific surface area possessing enhanced adsorption ability and photocatalytic activity

In this paper, one-dimensional titania nanorods were rapidly fabricated via a microwave-assisted polyol synthesis of titanium glycolate, followed by water treatment under microwave irradiation. The obtained results indicated that the TiO2 nanorods with micro-mesoporous structure and a large specific surface area can be obtained in a very short water treatment duration (20 min) at the relatively lower energy consumption of 385 W, compared to a conventional polyol method. The morphology and structure of TiO2 nanorods were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), zeta potential measurements and N2 adsorption/desorption technique. N2 adsorption–desorption analysis showed that TiO2 nanorods have a large mesopore and micropore surface area (345 m2/g and 49 m2/g, respectively). The adsorption ability and photocatalytic activity of all samples were evaluated by the elimination degradation of Rhodamine B from an aqueous solution under dark and UV-irradiation conditions. Experimental data showed that the sorption process follows the pseudo-second-order kinetic model. It was found that more than 30% of RhB was removed by titania nanorods after dark treatment in the first 2 min. Compared to P-25, the TiO2 nanorods displayed higher photocatalytic activity, with RhB removal percentage of ∼98% in 30 min. Thus, titania nanorods produced by this rapid and effective approach have a potential application as a highly active adsorbent and photocatalyst for degradation of the model organic dye Rhodamine B.

TiO2-induced photo-cross-linked electrospun polyvinyl alcohol nanofibers microfiltration membranes

The objective of this work is to investigate the feasibility of fabrication of photo-cross-linked polyvinyl alcohol (PVA) nanofibers membranes using citric acid as a cross-linking agent and TiO2 nanoparticles as a photo-catalyst in the absence of components with photoactive groups. The effects of TiO2 nanoparticles concentration and UV irradiation conditions on the surface properties, separation performance and anti-fouling properties of the membranes were studied. The results indicated that the TiO2 nanoparticles which were synthesized by a microwave hydrothermal method were successfully acted as a photo-catalyst absorbed the UV beam; consequently the cross-linking of the PVA matrix was occurred during the membrane preparation via the UV-irradiated electrospinning process. The obtained cross-linked PVA/TiO2 nanofibers membranes showed excellent water resistance and good mechanical properties. The PVA/TiO2 nanofibers membranes had higher permeation flux and oil rejection and lower fouling tendency in comparison to the neat PVA membrane.

Synthesis and characterization of SnO2, TiO2 and Ti0.5Sn0.5O2 nanoparticles as efficient materials for photocatalytic activity

This work reports the synthesis of polydispersible SnO2, TiO2 and Ti0.5Sn0.5O2 nanoparticles via microwave-assisted polyol as an efficient method using diethylene glycol (DEG) and triethylene glycol (TREG) as solvent. The properties of as-prepared samples were investigated by X-ray diffractometry, transmission electron microscopy, diffuse reflectance and FTIR spectrophotometery, photoluminescence spectroscopy and N2 physisorption. The X-ray diffraction patterns of the samples were indexed on the anatase phase of TiO2 and cassiterite phase of SnO2 and Ti0.5Sn0.5O2. The TEM images show uniform isotropic morphologies with average sizes close to10 nm. The band gap is reduced for Ti0.5Sn0.5O2 and enhances visible light absorption, a shift resulting in the absorption threshold towards the visible spectral range, compared to pure titania and tin. Slight shifts to longer wavelength are attributed to the change in the acceptor’s level induced by the mixture of both oxides. The evaluation of the photocatalytic activity is carried out using indigo carmine (IC) as model of chemical pollutants in UV irradiation conditions. The photocatalytic decolorization of the dye follows a pseudo-first-order kinetics and the constant apparent rate was increased with the increase of the tin oxide content up to 50%.

Transformation of avobenzone in conditions of aquatic chlorination and UV-irradiation

Emerging contaminants represent a wide group of the most different compounds. They appear in the environment at trace levels due to human activity. Most of these compounds are not yet regulated. Sunscreen UV-filters play an important role among these emerging contaminants. In the present research the reactions of 4-tert-butyl-4’-methoxydibenzoylmethane (avobenzone), the most common UV filter in the formulation of sunscreens, were studied under the combined influence of active chlorine and UV-irradiation. Twenty five compounds were identified by GC/MS as transformation products of avobenzone in reactions of aquatic UV-irradiation and chlorination with sodium hypochlorite. A complete scheme of transformation of avobenzone covering all the semivolatile products is proposed. The identification of the two primary chlorination products (2-chloro-1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione and 2,2-dichloro-1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione) was confirmed by their synthesis and GC/MS and NMR analysis. Although the toxicities of the majority of these products remain unknown substituted chlorinated phenols and acetophenones are known to be rather toxic. Combined action of active chlorine and UV-irradiation results in the formation of some products (chloroanhydrides, chlorophenols) not forming in conditions of separate application of these disinfection methods. Therefore caring for people «well-being» it is of great importance to apply the most appropriate disinfection method. Since the primary transformation products partially resist powerful UV-C irradiation they may be treated as stable and persistent pollutants.

Patterned Co-culture of Live Cells on a Microchip by Photocrosslinking with Benzophenone.

The patterned coculture of different types of living cells in a microfluidic device is crucial for the analysis of cellular interactions and cell-cell communication. In the present study, cell patterning was achieved by photocrosslinking benzophenone derivatives in a microfluidic channel. Optimization of UV irradiation conditions enabled successful fixation of live cells. In addition, patterning and co-culture of non-adherent K562 cells and adherent RF-6A cells was achieved by successive rounds of patterning. The present approach is expected to be useful for the development of in vitro methods for studying cell signaling.

Synthesis of TiO2 coated ZnO nanorod arrays and their stability in photocatalytic flow reactors

Immobilized photocatalysts are preferred over suspended catalyst particles in slurry reactors due to elimination of filtration process. The requisite condition for their use is the mechanical and chemical stability under flow conditions. The stability of TiO2 coated ZnO nanorods (TiO2/ZnO) immobilized at the bottom of a prototype continuous-flow reactor designed in the form of a rectangular channel is investigated under continuous flow conditions in this work. Morphology and structure of the nanorod arrays are characterized by field emission scanning electron microscopy and X-ray diffraction. Optical properties of the rods are determined by UV–Vis spectroscopy measurements. Dissolution trends of zinc ions from the TiO2/ZnO rods are determined under dark, UV radiation and photodegradation conditions, and compared with the results of uncoated ZnO. The effect of the number of TiO2 film coatings and the calcination time of the spin-coated films are investigated as parameters. Coating of the ZnO nanorods with TiO2 has greatly reduced its dissolution under UV radiation to a level less than the dissolution of uncoated ZnO rods in complete darkness. Photocatalysis under UV radiation was found to increase the dissolution rate of zinc ions. This increase was attributed to cavity or pit formation on the upper surfaces of nanorods. TiO2 coating was found to decrease the dissolution rate significantly by reducing the extent of pit formation. TiO2 was also found to increase the catalytic effectiveness of ZnO nanorod film in the photodegradation of methyl orange dye selected as a model organic pollutant.