Effect Of UV Intensity Research Articles

Antistatic epoxy acrylate/graphene oxide UV-curable coatings with improved shrinkage and adhesion strength

This study presents a simple method for preparing antistatic UV curable coating based on graphene oxide (GO). For this aim, epoxy acrylate (EA) was selected as a UV-curable matrix and synthesized GO nanoplates were dispersed in the resin through solvent-mediated dispersion. Simultaneous crosslinking of UV-curable resin and photoreduction of GO nanoplatelets take place during UV irradiation. The effect of UV intensity and concentration of graphene oxide on the curing kinetics of UV-curable nanocomposite and reduction of GO nanoplatelets was investigated. The results show that the curing reactions of the UV-curable system are disturbed by GO nanoparticles to some extent (depending on UV intensity). They also show that the electrical resistance of the UV-cured EA/GO nanocomposites decreases during the UV curing process. It was found that the shrinkage of the formulations improved considerably with the incorporation of GO into the formulations. The adhesion strength of the cured EA/GO coatings to mild steel was also found to be significantly higher than that of EA coating.

A comparative study on the degradation of phenylurea herbicides by UV/persulfate process: Kinetics, mechanisms, energy demand and toxicity evaluation associated with DBPs

The degradation performance of selected phenylurea herbicides (isoproturon and chlorotoluron) by UV/persulfate (PS) as well as toxicity assessments associated with disinfection by-products (DBPs) in subsequent oxidation were comparatively studied. The elimination of herbicides followed pseudo first-order kinetics well. Then effects of UV intensity, pH, PS dosage and water matrix (background ions and Nature organic matter (NOM)) were investigated detailedly. Increased kobs values were observed at higher PS dosages and greater UV intensity, but the degradation was basically resistant to pH variation. kobs could be inhibited by coexistent ions and NOM. Radical scavenging study revealed the more important role of sulfate radical (SR, SO4•−) than hydroxyl radical (HR, HO•). kapp of HO• and SO4•− towards isoproturon and chlortoluron were determined respectively. The results also indicated that the relative reactivity of alkyl- or halogen- substituted phenylurea herbicides with HO• and SO4•− can be correlated with Hammett constants as the molecular descriptor. Then a quantitative structure-activity relationship was established to predict the structure-dependent reactivity of phenylurea herbicides by UV/PS concerning substituent effects. The energy demand of UV/PS system was evaluated. The degradation intermediates by direct UV, UV/H2O2 as well as UV/PS were comparatively identified and the related destruction pathways were postulated. Compared with UV and UV/H2O2, UV/PS was superior in controlling the DBPs generation in post-disinfection of these herbicides. The data supported that SR-advanced oxidation processes (AOPs) had more advantages in removal efficiency and toxicity control than HR-AOPs. This study provided some theoretical bases for the UV/PS degradation behaviors of structurally similar phenylurea herbicides with regard to different substituents on the aromatic ring.

Development and evaluation of a point-of-use UV appliance for fresh produce decontamination

In-house treatment strategy for fresh produce decontamination has not been emphasized as much as industrial washing. The most common treatment for fresh produce decontamination and cleaning at home and other point-of-use places such as cafeteria is rinsing and/or soaking in a sink. In this study, an appliance utilizing UV and agitated water to decontaminate fresh produce was developed and its effectiveness was investigated in an aim to identify optimum processing parameters. Grape tomato and spinach representing two different surface smoothness were dip-inoculated in a four-strain Salmonella cocktail to reach a final population of 5–8 log CFU/g and air-dried. The produce samples were then washed in 1 gallon tap water under varying conditions, water agitation speed (0–190 RPM), sample size (50–400 g), UV intensity (0–30 mW/cm2) and treatment time (2, 5 and 10 min). In general, increasing the agitation speed and UV intensity enhanced Salmonella inactivation for both grape tomato and spinach. Sample size significantly affected the UV inactivation of Salmonella on grape tomato, but not on spinach. The effect of extending treatment time from 2 to 10 min was insignificant for almost all the UV treatments and the controls. The effect of UV intensity and treatment time on inactivation of Salmonella on spot-inoculated grape tomato and spinach was also determined. The most severe treatment used in this study, 30 mW/cm2 UV for 10 min, resulted in >4 log reductions of Salmonella dip- or spot-inoculated on grape tomato (200 g sample size and 190 RPM agitation speed) and 3.5 log reductions of Salmonella dip- or spot-inoculated on spinach (100 g sample size and 110 RPM agitation speed). We foresee that the UV appliance developed and evaluated in this study could be further fine-tuned and optimized to eventually construct a point-of-use UV appliance that can be used at home, cafeteria, restaurants, and hospitals for fresh produce decontamination and cleaning. The UV appliance could be an inexpensive and effective tool to improve fresh produce safety.

The study of correlation between electrical conductivity of solution-processed ZnO film and UV irradiation

This study investigated the correlation between the electrical conductivity of solution-processed ZnO film and UV irradiation. As-deposited ZnO film without UV irradiation was found to have a high resistivity, while the resistivity of UV irradiated ZnO film drastically decreased, owing to photo-induced doping under UV irradiation. The effect of UV intensity on the decomposition rate of organic substance indicated proportional relation. In addition, a transparent electric circuit was fabricated by UV patterning.

Preparation of PMMA nanolatex via microemulsion polymerization initiated by UV direct radiation at low temperature

By combining the microemulsion polymerization with UV direct initiation, an efficient polymerization method was developed due to its advantages in terms of high polymerization rate and conversion, lower polymerization temperature, high purity polymer. To be more specific, in the absence of initiator and under UV direct radiation, the polymerizations of MMA/Water/emulsifier microemulsion system were successfully accomplished at low temperature (26 ∼ 35°C) and PMMA nanolatex with the average diameter of 9.5 nm and narrow diameter distribution was obtained. The effects of UV intensity, monomer concentration, emulsifier concentration and temperature on polymerization rate and intrinsic viscosity of polymer were researched. The apparent activation energy of the reaction and polymerization kinetics of Rp are obtained as the following: Rp∝[IUV] 1.25[M]1.04[E]−2.57, Ea=14.45KJ/mol.

Effect of different UV intensity on corrosion behavior of carbon steel exposed to simulated Nansha atmospheric environment

Effect of UV intensity on the corrosion behavior of carbon steel exposed to simulated Nansha atmospheric environment has been investigated using weight loss measurement, a stereomicroscope, a laser scanning confocal microscope (LSCM), a scanning electron microscope (SEM), X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS). According to the results, when UV intensity is higher enough, the corrosion rate was accelerated significantly. As UV intensity increasing, the surface roughness of the rusted sample was not changed much at the initial stage. After long time exposure, the roughness became lager and the rust layer became thicker with many voids and cracks distributing in the rust layer. The composition of corrosion products were the same, but the relative content of different kind FeOOH was changed as UV intensity increased.

Oxidation and biotoxicity assessment of microcystin-LR using different AOPs based on UV, O3 and H2O2

Microcystin-LR attracts attention due to its high toxicity, high concentration and high frequency. The removal characteristics of UV/H2O2 and O3/H2O2 advanced oxidation processes and their individual process for MC-LR were investigated and compared in this study. Both the removal efficiencies and rates of MC-LR as well as the biotoxicity of degradation products was analyzed. Results showed that the UV/H2O2 process and O3/H2O2 were effective methods to remove MC-LR from water, and they two performed better than UV-, O3-, H2O2-alone processes under the same conditions. The effects of UV intensity, H2O2 concentration and O3 concentration on the removal performance were explored. The synergistic effects between UV and H2O2, O3 and H2O2 were observed. UV dosage of 1800 mJ ·cm–2 was required to remove 90% of 100 mg·L–1 MC-LR, which amount significantly decreased to 500 mJ·cm–2 when 1.7 mg·L–1 H2O2 was added. 0.25 mg·L–1 O3, or 0.125 mg·L–1 O3 with 1.7 mg·L–1 H2O2 was needed to reach 90% removal efficiency. Furthermore, the biotoxicity results about these UV/H2O2, O3/H2O2 and O3-alone processes all present rising trends with oxidation degree of MC-LR. Biotoxicity of solution, equivalent to 0.01 mg·L–1 Zn2+, raised to 0.05 mg·L–1 Zn2+ after UV/H2O2 or O3/H2O2 reaction. This phenomenon may be attributed to the aldehydes and ketones with small molecular weight generated during reaction. Advice about the selection of MC-LR removal methods in real cases was provided.

Inactivation of Nonpathogenic Escherichia coli, Escherichia coli O157:H7, Salmonella enterica Typhimurium, and Listeria monocytogenes in Ice Using a UVC Light-Emitting Diode

Ice, widely used in the food industry, is a potential cause of food poisoning resulting from microbial contamination. Direct microbial inactivation of ice is necessary because microorganisms may have been present in the source water used to make it and/or may have been introduced due to poor hygiene during production or handling of the ice. Nonthermal and nondestructive microbial inactivation technologies are needed to control microorganisms in ice. We evaluated the applicability of a UVC light-emitting diode (UVC-LED) for microbial inactivation in ice. The effects of UV intensity and UV dose of the UVC-LED on Escherichia coli ATCC 25922 and a comparison of UVC-LED with a conventional UV lamp for effective bacterial inactivation in distilled water and ice cubes were investigated to evaluate the performance of the UVC-LED. Finally, we assessed the effects of the UVC-LED on pathogens such as E. coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in ice cubes. The results indicated that UVC-LED effectiveness depended on the UV dose at all UV intensity conditions (0.084, 0.025, 0.013, 0.007, and 0.005 mW/cm2) in ice and that UVC-LED could more efficiently inactivate E. coli ATCC 25922 in distilled water and ice than the UV lamp. At a UV dose of 2.64 mJ/cm2, E. coli in distilled water was decreased by 0.90 log CFU/mL (UV lamp) and by more than 7.0 log CFU/mL (UVC-LED). At 15.2 mJ/cm2, E. coli in ice was decreased by 3.18 log CFU/mL (UV lamp) and by 4.45 CFU/mL (UVC-LED). Furthermore, UVC-LED irradiation reduced the viable number of pathogens by 6 to 7 log cycles at 160 mJ/cm2, although the bactericidal effect was somewhat dependent on the type of bacteria. L. monocytogenes in ice was relatively more sensitive to UVC irradiation than were E. coli O157:H7 and Salmonella Typhimurium. These results demonstrate that UVC-LED irradiation could contribute to the safety of ice in the food industry.

UV crosslinked mRNA-binding proteins captured from leaf mesophyll protoplasts.

BackgroundThe complexity of RNA regulation is one of the current frontiers in animal and plant molecular biology research. RNA-binding proteins (RBPs) are characteristically involved in post-transcriptional gene regulation through interaction with RNA. Recently, the mRNA-bound proteome of mammalian cell lines has been successfully cataloged using a new method called interactome capture. This method relies on UV crosslinking of proteins to RNA, purifying the mRNA using complementary oligo-dT beads and identifying the crosslinked proteins using mass spectrometry. We describe here an optimized system of mRNA interactome capture for Arabidopsis thaliana leaf mesophyll protoplasts, a cell type often used in functional cellular assays.ResultsWe established the conditions for optimal protein yield, namely the amount of starting tissue, the duration of UV irradiation and the effect of UV intensity. We demonstrated high efficiency mRNA-protein pull-down by oligo-d(T)25 bead capture. Proteins annotated to have RNA-binding capacity were overrepresented in the obtained medium scale mRNA-bound proteome, indicating the specificity of the method and providing in vivo UV crosslinking experimental evidence for several candidate RBPs from leaf mesophyll protoplasts.ConclusionsThe described method, applied to plant cells, allows identifying proteins as having the capacity to bind mRNA directly. The method can now be scaled and applied to other plant cell types and species to contribute to the comprehensive description of the RBP proteome of plants.Electronic supplementary materialThe online version of this article (doi:10.1186/s13007-016-0142-6) contains supplementary material, which is available to authorized users.

紫外光降解吲哚的研究

本文首次对吲哚溶液进行紫外光降解研究，主要考查了紫外辐射强度、pH值、羟基自由基、自由基抑制剂、水中常见无机阴离子、碱度及腐殖酸等因素对吲哚降解的影响。结果表明，紫外辐射强度、羟基自由基和碱度都会促进吲哚降解，自由基抑制剂和腐殖酸起抑制作用，而常见无机阴离子对吲哚降解影响不大。对于pH值而言，当pH ≤ 7时其影响不大，当pH > 7时会加速吲哚降解。 The effects of UV intensity, pH value, hydroxyl radical, hydroxyl radical inhibitor, ordinary orga-nicanions, alkalinity, and humic acid on the degradation efficiency of indole by ultraviolet light were studied for the first time. The results show that UV intensity, hydroxyl radical, and alkalinity can accelerate degradation efficiency, and hydroxyl radical inhibitor and humic acid inhibit it, while ordinary organic anion has little influence on it. For pH value, the degradation efficiency of indole increases when pH > 7, while it almost remains unchanged when pH ≤ 7.

Effects of UV Intensity, Line-speed, and Light Distribution on Conversion and Surface Elastic Modulus of Roll-to-roll UV-cured Film

Effects of UV Intensity, Line-speed, and Light Distribution on Conversion and Surface Elastic Modulus of Roll-to-roll UV-cured Film

Decontamination of poultry feed from ochratoxin A by UV and sunlight radiations.

Mycotoxin-contaminated feed is very dangerous for the growth and even life of poultry. The objective of the current study was to investigate the efficacy of ultra-violet irradiation for decontamination of ochratoxin A (OTA) in spiked and naturally contaminated poultry feed samples. Spiked and naturally contaminated feed samples were irradiated with ultra-violet light (UV) at distance of 25 cm over the feed samples. In vitro, the effect of UV intensity (0.1 mW cm(-2) at 254 nm UV-C) on different types of poultry feeds contaminated with OTA was evaluated. The same samples were also irradiated with sunlight and analysed for OTA by an indirect enzyme linked immunosorbent assay method. Poultry feed samples containing 500 µg kg(-1) were 100% decontaminated in 180 min with UV radiation while OTA was decreased to 70-95 µg kg(-1) using the same poultry feed samples after 8 h sunlight irradiation. Therefore, UV light was found to be more effective. Only 1 h of UV irradiation was found to be sufficient to bring the OTA level to the maximum regulatory limit suggested for poultry feeds (100 µg kg(-1) ), while 8 h were needed to obtain this level using sunlight radiations. The proposed approach is a viable option to reduce the level of OTA in contaminated poultry feeds. © 2015 Society of Chemical Industry.

Ag-TiO2 nanoparticles for photocatalytic degradation of lomefloxacin

The photocatalytic activity of silver-doped TiO2 (Ag-TiO2) nanoparticles was studied by photocatalytic degradation of lomefloxacin (LMF) using a photoreactor with a mercury lamp (PHILIPS, TUV 8W T5, Emax = 254 nm). The 1 and 2% silver-doped TiO2 nanoparticles were synthesized by liquid impregnation (LI) method. The resulting nanoparticles were characterized by surface analytical methods such as X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray analysis and transmission electron microscope (TEM). The study shows 2% Ag-TiO2 nanoparticles exhibited better results (95% degradation) in 1 h for the degradation of lomeofloxacin compared to 1% Ag-TiO2 and pure TiO2. XRD analysis indicated that the crystallite size of TiO2 was 17.00 nm, while the crystallite size of 1% Ag-TiO2 and 2% Ag-TiO2 was 13.07 to 14.17 nm. TEM images show the particle size of Ag-TiO2 nanoparticles were in the range 40–45nm in length and 10–15nm in breadth. Pseudo-first-order rate constants were found to decrease with increase in pH. The effect of UV intensity, catalyst dosage and initial concentration of LMF on the degradation rate were also studied and elaborately discussed.

The influence of clay brick substratum on the inhibitory efficiency of TiO2 nanocoating against biofouling

The goal of this study was to explain the influence of the total porosity and the surface roughness on the susceptibility of clay bricks to biodegradation by phototrophic microorganisms. In addition, this correlation was studied on both specimens treated with TiO2 nanocoating and untreated control specimens. The effect of UV intensity on the photocatalytic power of TiO2 was also investigated.An accelerated fouling test was performed by sprinkling a suspension of Chlorella mirabilis and Chroococcidiopsis fissurarum on sample surfaces. These two test strains were chosen because their representativeness on building clay brick façades subjected to biofouling. The gradual superficial accumulation of algal biomass on treated and control specimens was evaluated by means of image analysis and colour measurement. Two specimens' parameters, namely porosity and roughness, were examined.Results showed that both the specimen microstructure and roughness of the surface play a key role in the colonization of clay bricks because they were able to provide more nutrient to the algal cells anchored to the surface. The TiO2 nanocoating was able to inhibit the biofouling of clay bricks irradiated with UV-A light, except in the case of high porous rough specimens.

Photocatalytic decomposition of crotamiton over aqueous TiO2 suspensions: Determination of intermediates and the reaction pathway

The photocatalytic degradation of crotamiton in aqueous solution using TiO2 was investigated. To investigate the effect of initial pH, the photodegradation behaviors of three types of pharmaceuticals were compared (crotamiton, clofibric acid, sulfamethoxazole). The degradation rates of crotamiton in the pH range 3–9 were nearly equal, but those of clofibric acid and sulfamethoxazole were affected by pH. At pH>6.5, TiO2 particles, clofibric acid and sulfamethoxazole had negative charge, therefore, the repulsive force between TiO2 particles and anionic pharmaceuticals occurred and a low reaction rate at high pH was observed. The effect of UV intensity and TiO2 concentration on photodegradation efficiency was also investigated. Linear and logarithmical relationships between UV intensity, TiO2 concentration and the reaction rate constant were confirmed. Furthermore, the structures of photodegradation intermediates formed concomitantly with the disappearance of crotamiton were estimated. Seven intermediates were characterized by LC/MS/MS analyses, and it was assumed that the photocatalytic degradation of crotamiton was initiated by the attack of electrophilic hydroxyl radicals on aromatic rings and alkyl chains.

Photodegradation kinetics and byproducts identification of the Aflatoxin B1 in aqueous medium by ultra‐performance liquid chromatography–quadrupole time‐of‐flight mass spectrometry

A photodegradation study of Aflatoxin B(1) (AFB(1)) in water solution was performed under UV irradiation at different AFB(1) initial concentrations and UV irradiation intensities. The effect of UV intensity on the AFB(1) photodegradation ratio is dominative, when compared with AFB(1) initial concentration. The photodegradation of AFB(1) was proved to follow first-order reaction kinetics (R(2) > or = 0.99). Three photodegradation products, i.e. P(1) (C(17)H(14)O(7)), P(2) (C(16)H(14)O(6)) and P(3) (C(16)H(12)O(7)), were identified on the basis of low mass error and high matching property by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF MS), and the degradation pathway was proposed. This study first reports the appearance of these photodegradation products and the proposed degradation pathway in aqueous media.

Effect of UV intensity on structure, water sorption, and transport properties of crosslinked N-vinyl-2-pyrrolidone/N,N′-methylenebisacrylamide films

UV photopolymerization was used to prepare films from N-vinyl-2-pyrrolidone (NVP) crosslinked with N,N′-methylenebisacrylamide (MBAA). These samples were crosslinked in the presence of water. Although the initial mixtures of water, NVP and MBAA were optically transparent, the final films were white, indicating that phase separation occurred during photopolymerization. The influence of UV intensity on the crosslinked NVP film structure was characterized using CryoSEM for cross-sectional imaging and Bio-AFM for imaging surface morphology. The influence of UV intensity on transport properties was characterized using dead-end filtration to measure water permeability and molecular weight cutoff (MWCO). Samples polymerized at high UV intensity had 2.7 times higher water permeability than those polymerized at low UV intensity, even though the structure, as probed via SEM and AFM, shows little to no significant changes. Higher UV intensity also led to somewhat higher MWCO values, indicating a tradeoff between water permeability and solute sieving characteristics.

A loop-based approach in clustering and routing in Mobile Ad hoc NETworks

The effects of UV intensity and turbidity on selected microbial indicator inactivation were investigated. Results showed that UV disinfection was effective in killing all the selected microbial indicators, the resistance order of the microorganisms was as follows: MS-2 coliphage > Bacillus subtilis > E. coli > Staphylococcus aureus and Candida albicans. UV intensity had influence on the inactivation of all the microorganisms, high UV disinfection efficency was obtained with higher UV intensity. Turbidity had impact on the bacteria inactivation rate, but there was no evidence that turbidity had any negative contribution to MS-2 coliphage. Under the same UV dosage, higher UV intensity could overcome the negative influence of turbidity on UV performance, enhanced microorganism inactivation effect in turbidity water.

Photoinitiating behavior of bifunctional photoinitiator containing α-hydroxyalkylphenone group on free-radical polymerization

Photoinitiating behaviors of bis[4-(2-hydroxy-isopropionyl)]ether photoinitiator on free-radical polymerization have been investigated. The kinetics of photopolymerization initiated by the photoinitiator was studied by means of differential photocalorimetry. The bifunctional photoinitiator showed comparative performance with those commercial photoinitiators with monofunctional chromophoric group. The effect of UV intensity on the polymerization rate was investigated, and the value of exponential factor was found to be 0.5 at the beginning of polymerization, suggesting that the photopolymerization initiated by bis[4-(2-hydroxy-isopropionyl)]ether followed biradical termination mechanism. Photosensitizer triethylamine improves the initiating efficiency while oxygen is shown to restrict polymerization in this system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5297–5302, 2006

Nanofiltration membrane prepared from cardo polyetherketone ultrafiltration membrane by UV-induced grafting method

Hydrophilic nanofiltration membranes were prepared by graft polymerization of hydrophilic monomers onto the surface of ultrafiltration membranes made from cardo polyetherketone (PEK-C). The method consists of a UV irradiation in the presence of acrylic for an in situ graft polymerization of polyacrylic acid (PAA) on the surface of the UF membranes. The effect of UV intensity, irradiation time and monomer nature on the membrane performances were investigated. Analyses by Fourier transform infrared in attenuated total reflection mode, contact angles and atomic force microscopy of the modified membrane surface showed that the degree of grafting of the membrane surface and their hydrophilicity increased with the irradiation time. The retention of sodium chloride and sodium sulfate of the membrane with poly(acrylic acid) grafted for 1 min of UV irradiation under a 8.7 mW/cm 2 lamp were 57 and 95.7%, respectively, while the water flux of the membrane was ca. 25 L m −2 h −1, at 0.8 MPa. The changes in the membrane permeability and the salt retention with different grafting parameters suggest that, under a high enough irradiation power and monomer concentration in the surrounding medium, enough PAA chains are grafted on the pores wall to convert the pores of an UF membranes to the NF-type pores (sodium sulfate retention close to 100%) within a few minutes. Further irradiation adds new PAA grafts in the plain polymer surface, without significant changes in the pores, i.e. in the membrane performances. The grade of the obtained NF membrane can be controlled by monitoring the monomer concentration or the irradiation power in order to graft progressively PAA chains on the pores.