High-pressure Mercury Arc Research Articles

Ультрафіолетове опромінення препарату «KENO CID 210»

The effectiveness of the process of photoactivation of aqueous solutions has been proven by studies conducted in the article. As a method of exposure, UV radiation is low-cost and natural, so there is a need to study the effect of ultraviolet radiation on aqueous disinfectant solutions and to determine effective methods of irradiation. Accordingly, there is a need to investigate the effect of UV radiation on disinfectants, in particular on their antimicrobial properties and to determine the effective effect of ultraviolet radiation on the tool. The high pressure mercury arc lamp DRT-400 lamp was used as a source of ultraviolet radiation. The surface of the aqueous solution was at a distance of 0.25 m under a source of UV radiation. The photoactivated liquid was applied to the agar medium immediately after inoculation of bacteria. The growth of colonies of microorganisms was recorded 24 hours after application of the treated disinfectant solution. At the Department of Electrical Engineering, Electromechanics and Electrical Technologies of NULES of Ukraine measurements of pH, redox potential of disinfectant solutions immediately after irradiation were carried out. Graphical dependences of changes of disinfecting properties are received. It is established that ultraviolet radiation significantly changes the pH and redox potential of aqueous solutions of disinfectants. The intensity of the parameter change is characteristic of ultraviolet radiation at an exposure of 5-15 minutes. Irradiation of сoncentrated disinfectant based on quaternary ammonium and glutaraldehyde «Keno Cid 210» solution for 5 minutes effectively inhibits the growth properties of microorganisms. The concentration of the irradiated aqueous disinfectant solution can be 5 times lower than the concentration of the non-irradiated.

The influence of the LED lighting on structural-functional parameters of lettuce plants

Comparative studies were conducted on morphofunctional parameters of lettuce (Lactuca sativa) plants cultivated with the use of supplementary lighting from different light sources – LED lamps, high-pressure mercury arc lamp (HPM) and high-pressure sodium arc lamp (HPS). The work showed that morphofunctional parameters of lettuce were significantly higher with LED lighting, in comparison to plants cultivated with HPM illumination, and main parameters of leaves grown under LED were barely discernible from the samples grown under HPS lighting. We observed accelerated transfer into reproductive period during HPM lighting, what can lead to quality degradation of the product. Considering the approximate values of leaf character range in experiments with HPS and LED lighting and greater energy efficiency of LED, light emitting diodes are obviously more promising for supplementary illumination in protected ground conditions.

The influence of different lighting sources on growth and development of tomato plants

Comparative study was conducted on morphofunctional parameters of tomato plants (Solanum lycopersicum L.) under diverse supplementary lighting conditions – electrodeless lamps (EL), high-pressure mercury arc lamps (HPM) and high-pressure sodium arc lamps (HPS). The work showed, that plants, cultivated under 5,000 lux EL lighting, had higher morphometric parameters, their leaves contained more chlorophyll, and they were outgrown, in comparison to plants, growth in HPS and HPM lighting conditions. These results demonstrate the profitableness of EL light flux, which contains constant PAR spectrum, for tomato plants growth and development.

A Novel Microtiter Plate Format High Power Open Source LED Array

Many photochemical or photobiological applications require the use of high power ultraviolet light sources, such as high-pressure mercury arc lamps. In addition, many photo-induced chemical, biochemical and biological applications require either a combinatorial setting or a parallel assay of multiple samples under the same environmental conditions to ensure reproducibility. To achieve this, alternative, controllable light sources, such as ultraviolet light emitting diodes (UV LEDs) with high power and spatial control are required. Preferably, LEDs are arranged in a suitable standardized 96-well microtiter plate format. We designed such an array and established the methods required for heat management and enabling stable, controllable illumination over time.

High-Power 365 nm UV LED Mercury Arc Lamp Replacement for Photochemistry and Chemical Photolithography.

Ultraviolet light emitting diodes (UV LEDs) have become widespread in chemical research as highly efficient light sources for photochemistry and photopolymerization. However, in more complex experimental setups requiring highly concentrated light and highly spatially resolved patterning of the light, high-pressure mercury arc lamps are still widely used because they emit intense UV light from a compact arc volume that can be efficiently coupled into optical systems. Advances in the deposition and p-type doping of gallium nitride have recently permitted the manufacture of UV LEDs capable of replacing mercury arc lamps also in these applications. These UV LEDs exceed the spectral radiance of mercury lamps even at the intense I-line at 365 nm. Here we present the successful exchange of a high-pressure mercury arc lamp for a new generation UV LED as a light source in photolithographic chemistry and its use in the fabrication of high-density DNA microarrays. We show that the improved light radiance and efficiency of these LEDs offer substantial practical, economic and ecological advantages, including faster synthesis, lower hardware costs, very long lifetime, an >85-fold reduction in electricity consumption and the elimination of mercury waste and contamination.

In vivo quantitative measurement of antioxidant effects in the lens

AbstractTo evaluate the protective effect of antioxidants on experimental cataract induced by ultraviolet radiation (UVR). The protective effect of the antioxidants alpha‐tocopherol and caffeine and the antioxidant gene Grx‐1 were investigated. For investigation of the antioxidants, albino Sprague Dawley rats were used and for the Grx‐1 gene, a Grx‐1 knockout C57BL/6 mouse and its inbred wild type were used. As an oxidation insult, all animals were exposed to around threshold dose UVR in the 300 nm wavelength region, delivered during 15 min. The UVR was generated with a high pressure mercury arc lamp and the waveband was limited to around 300 nm. Dosimetry was assured with a calibrated thermopile. The rats and mice were sacrificed at 1 week and 48 hrs after exposure, respectively. Then, the lenses were extracted for forward light scattering measurement. In all three experiments, the animals were grouped at five different dose levels centered around the expected threshold dose. The Maximum Tolerable Dose‐2.3;16 (MTD‐2.3;16) was used as threshold estimate. The protection factor (PF) was calculated as the ratio between the threshold dose with protective factor and the threshold without the protective factor. The threshold dose for alpha‐tocopherol was with and without 3.0 and 2.7 kJ/m^2, respectively (PF= 1.1). The threshold dose for caffeine was with and without 5.7 and 4.6 kJ/m^2, respectively (PF= 1.2). The threshold dose for Grx‐1 was with and without 3.8 and 3.0 kJ/m^2, respectively (PF= 1.3). As measured in vivo, caffeine has a more potent antioxidant effect after topical application than alpha‐tocopherol administered parenterally. The Grx‐1 gene provides the most potent antioxidant effect in vivo.

Atomic and Excitation Temperatures in Medium- and High-pressure Mercury Arc Lamps

Atomic and Excitation Temperatures in Medium- and High-pressure Mercury Arc Lamps

Photodissociation and photochemistry of V+(H2O)n, n = 1–4, in the 360–680 nm region

Photodissociation and photochemistry of V+(H2O)n, n = 1–4, was studied in 360–680 nm region using a Fourier transform ion cyclotron resonance mass spectrometer. The light of a high pressure mercury arc lamp was filtered using a set of bandpass filters with the center wavelengths from 360 to 680 nm in steps of 20 nm. The bandwidth of the filters, defined as full width at half maximum, was 10 nm. Photodissociation channels were attributed to loss of water molecules as well as atomic or molecular hydrogen, possibly accompanied by loss of water molecules. The most intense absorptions were red-shifted with increasing hydration. Theoretical spectra were calculated using time-dependent density functional theory. Calculations reproduced all the features of the experimental spectra, including the red shift with increasing hydration shell and the overall pattern of strong and weak absorption peaks.

Contribution to the numerical study of turbulence in high intensity discharge lamps

We present in this paper a comparison between results obtained with a laminar and turbulent models for high-pressure mercury arc. The two models are based on the resolution of bidimensional time-dependent equations by a semi-implicit finite-element code. The numerical computation of turbulent model is solved with large eddy simulation model; this approach takes into account the various scales of turbulence by a filtering method on each scale. The results show the quantitative influence of turbulence on the flow fields and also the difference between laminar and turbulent effects on the dynamic thermal behaviour and on the characteristics of the discharge.

Tunable Chiral Reaction Media Based on Two-Component Liquid Crystals: Regio-, Diastereo-, and Enantiocontrolled Photodimerization of Anthracenecarboxylic Acids

Three kinds of enantiopure amphiphilic amino alcohols (1a-c) were newly synthesized, of which the stereochemistry of the stereogenic carbons adjacent to the amino (C2) and hydroxy (C1) groups was systematically varied. By using these amino alcohols and four photoreactive carboxylic acids, 12 kinds of salts were prepared. The structure and thermal behavior of the salts were thoroughly investigated by various techniques, which revealed that the stereochemistry of the amino alcohol unit has significant effects on the properties of the salts; the salts of 1a with (1R,2S)-configuration did not exhibit any liquid crystal (LC) phase but showed high crystallinity, whereas 1b and 1c with (1S,2S)- and (1S)-configurations, respectively, generally afforded stable LC salts with smectic structure(s). Within the matrix of these amphiphilic salts, the in situ photodimerizations of 2-anthracenecarboxylic acid (2c) and 1-anthracenecarboxylic acid (2d) were conducted by the irradiation with UV/vis light (500 W, a high-pressure mercury arc lamp, >380 nm). Concerning reactivity and regio-/diastereo-/enantioselectivities, the LC phases were found to be superior to isotropic and crystalline phases. For the two substrates 2c and 2d, every LC phase promoted the photodimerization with unprecedentedly high head-to-head selectivity. Particularly in the case of 2c, diastereoselecitivity (syn(HH) vs anti(HH)) could be rationally controlled by the choice of the amino alcohol unit and mesophase (syn(HH):anti(HH) = 61:37 to 26:72). Moreover, one of the LC phases exhibited by 1b·2c afforded the anti(HH)-dimer of 2c with excellent enantioselectivity (up to 86% ee). On the basis of the hypothesis that the present photochemical outcome arises from the preorientation of the substrates, a preliminary structural model of these LCs was proposed.

Difluoro‐λ5‐Phosphinonitrile F2PN: Matrix Isolation and Photoisomerization into FPNF

Splendid isolation: Monomeric phosphazene F(2)PN ((1)A(1)) was prepared for the first time through irradiation of F(2)PN(3) in an argon matrix with an ArF excimer laser (lambda=193 nm). Upon subsequent irradiation with a high-pressure mercury arc lamp (lambda=255 nm), F(2)PN undergoes a 1,2-fluorine shift to give iminophosphane cis-FP=NF.

Photodegradation of Crude Oil on a Solid Support

The modifications of crude oil after absorption on silica, montmorillonite, and zeolite were studied. Solid-phase microextraction gas chromatography-mass spectrometry analysis showed that some compounds are kept better by the solid support than other ones. The modifications that occurred were studied considering the relative amount of different classes of compounds, the number of compounds in function of the number of carbon atoms, and the relative amount in function of the number of carbon atoms for different classes of compounds (linear alkanes, branched alkanes, cyclic alkanes, aromatic hydrocarbons, and alkenes). The modifications which occurred after irradiation with a 125 W high pressure mercury arc towards Pyrex were studied. A global index of the modifications which occurred was proposed. All of the solids prevent photodegradation. Zeolite was the worst, while the most preservative effect was showed by montmorillonite.

Unified modelling of near-cathode plasma layers in high-pressure arc discharges

A model of a near-cathode region in high-pressure arc discharges is developed in the framework of the hydrodynamic (diffusion) approximation. Governing equations are solved numerically in 1D without any further simplifications, in particular, without explicitly dividing the near-cathode region into a space-charge sheath and a quasi-neutral plasma. Results of numerical simulation are reported for a very high-pressure mercury arc and an atmospheric-pressure argon arc. Physical mechanisms dominating different sections of the near-cathode region are identified. It is shown that the near-cathode space-charge sheath is of primary importance under conditions of practical interest. Physical bases of simplified models of the near-cathode region in high-pressure arc discharges are analysed. A comparison of results given by the present model with those given by a simplified model has revealed qualitative agreement; the agreement is not only qualitative but also quantitative in the case of an atmospheric-pressure argon plasma at moderate values of the near-cathode voltage drop. The modelling data are compared with results of spectroscopic measurements of the electron temperature and density in the near-cathode region.

Synthesis of new polyazines by 1,4 photochemical or anionic polymerization of 1,2-diaza-1,3-butadienes

Photochemical and anionic polymerizations of 1,2-diaza-1,3-butadienes are described. Photochemical polymerization was smoothly performed by irradiation of some 1-aminocarbonyl-1,2-diaza-1,3-butadienes with high pressure mercury arc ( λ = 300 nm) in the presence of allyltributylstannane. Molecular weights ( M w) in the range 14.6–559 × 10 2 g/mol were obtained. The TGA curve revealed a first weight loss starting at about 200 °C of some 85%, and a second starting at about 300 °C. The DSC showed the glass transition ( T g) at about −34 °C. Anionic polymerization was performed by treatment of some 1-alkoxycarbonyl-1,2-diaza-1,3-butadienes with n-butyllithium. Molecular weights ( M w) in the range 8.44–242 × 10 2 g/mol were obtained.

Measuring solid-state quantum yields: The conversion of a frequency-doubled Nd:YAG diode laser pointer module into a viable light source

This article outlines the difficulties associated with measuring quantum yields for solid-state samples using a high-pressure mercury arc lamp as the irradiation source. Details are given for the conversion of an inexpensive frequency-doubled neodymium-doped yttrium aluminum garnet (Nd:YAG) diode laser pointer module into a viable irradiation source. The modified Nd:YAG laser was incorporated into a computer-controlled system, which allowed for the simultaneous irradiation and spectroscopic monitoring of the sample. The data obtained with the Nd:YAG diode laser system show far less scatter than data obtained with a high-pressure Hg arc lamp, and consequently the degradation rates obtained with the laser system could be calculated with far greater accuracy.

Solvothermal synthesis of visible light responsive nitrogen-doped titania nanocrystals

Nitrogen ion-doped titania nanoparticles were obtained by the homogeneous precipitation in hexamethylenetetramine-titanium trichloride mixed solution followed by heat treatment in the solution at desired temperatures. After that the sample powders obtained were calcined in air at desired temperatures. Various phases of titania such as anatase, rutile and brookite were obtained depending on the reaction condition. Crystallite size, specific surface area and color also greatly changed as 5-50 nm, 20--200 m2·g-1 and light gray-yellow, respectively, depending on the solvent, pH, etc. The products after calcination around 400°C were yellow indicating doping with nitrogen ion. Photocatalytic activity for the oxidative decomposition of NO in air atmosphere was also evaluated by using a continuous flow system with 1 ppm NO gas, where the high pressure mercury arcs filtered using various filters were irradiated. All colored titania nanoparticles showed photocatalytic activity under visible light irradiation for the oxidative decomposition of nitrogen monoxide in air. Especially, the nanoparticles of anatase type nitrogen-doped titania obtained by the homogeneous precipitation using hexamethylenetetramine-methanol aqueous solution around 200°C showed excellent photocatalytic activity under visible light irradiation.

Abiotic Degradation of Iodosulfuron-methyl-ester in Aqueous Solution

The abiotic degradation of iodosulfuron-methyl-ester was investigated under both alkaline and acidic pH conditions in the dark, and results showed it to be a rather stable molecule in neutral or slightly alkaline environments. Photochemical reactions were studied using a high-pressure mercury arc lamp, and results showed that direct phototransformation is possible under normal environmental conditions (lambda > 290 nm). High-performance liquid chromatography (HPLC-UV and HPLC-MS) analyses were used to identify the degradates and to study the kinetics of photodecomposition and hydrolysis. Five main products of iodosulfuron-methyl-ester degradation were tentatively identified, and one of them (4-methoxy-6-methyl-1,3,5-triazin-2-amine) was confirmed using an authentic standard. Among the phototransformation mechanisms, photosubstitution of the iodide atom by a hydroxyl group, photodissociation of the N-S bond, and photoassisted hydrolysis were observed. The quantum efficiencies (multiwavelength quantum yield) of the photodegradation under different conditions were determined, and values of 0.054 +/- 0.02 (pH 9.6), 0.08 +/- 0.02 (pH 7), and 0.044 +/- 0.008 (pH 5.3) were obtained.

Photochemical reaction of Tl in aqueous solution and its environmental significance

The valence state of thallium determines its toxicity, distribution and mobility. Tl(I) can be oxidized to Tl(III) under photoirradiation of the high-pressure mercury arc lamp and solar light. A photooxidation experiment of thallium showed that the photooxidation rate could be affected by the pH of the solution, and the intensity and wavelength of the light source. Lowering the pH and increasing the light intensity have the effect of increasing the photooxidation rate. UV radiation (UVB and UVC regions) plays an important role in the photooxidation of Tl(I). However, the microbial effect is not obvious in comparison with photooxidation effect in this experiment. The study can provide important scientific groundwork for handling of thallium pollution.

Photochemical behaviour of carbendazim in aqueous solution.

To elucidate the photochemical behaviour of carbendazim (or MBC) in superficial waters, photolysis studies have been carried out in aqueous solutions at several pH using a UV light source (high pressure mercury arc lamp) or a solar light simulator (xenon arc lamp). The kinetics of photodecomposition of carbendazim was determined using HPLC-DAD and the identification of photoproducts was carried out with HPLC-MS (ESI negative and positive mode). According to the experimental results carbendazim is a rather stable molecule in the dark or in environmental conditions. The pH influence of the environmental medium on the photodegradation rate has been confirmed. The photochemical process can be considerably accelerated in alkaline solutions using HPK-quartz irradiation (quantum efficiency at pH 9 phi = 3.1 x 10(-3) degraded molecule per absorbed photon) while the photodegradation is not as efficient under a simulated sun irradiation (quantum efficiency in the suntest phi = 10(-4) at pH 7). Three photoproducts have been tentatively identified in pure water: 2-aminobenzimidazole, benzimidazole isocyanate and monocarbomethoxy-guanidine (issued from the cleavage of the benzimidazole ring). The last one seems very stable and could be accumulated in the environment.

Assessment of the toxicity of methyl parathion and its photodegradation products in water samples using conductometric enzyme biosensors

An assessment of the toxicity of methyl parathion and products of its photodegradation in water samples was performed using conductometric biosensors based on thin films planar electrodes and immobilized cholinesterases. All photodegradation experiments were carried out using a quartz reaction cell equipped with a 125 W high pressure mercury arc lamp as source of radiation. The photodegradation kinetics can be described as a first-order degradation curve C=C 0 e −kt , where C 0=(9.1±0.1)×10 −5 M, k=0.026±0.001 min −1 and t 1/2=26 min. The high performance liquid chromatography (HPLC) was used to identify and quantify methyl paraoxon and 4-nitrophenol as main methyl parathion photoproducts. It was shown for the first time by using conductometric enzyme biosensor that the inhibition effect on the acetyl cholinesterase (AcChE) activity increases dramatically as soon as the photodegradation of methyl parathion begins. Methyl paraoxon is about 10 times more toxic than methyl parathion. The toxicity curve does not exactly follow the appearance of methyl paraoxon. The results obtained could be explained by a strong synergistic effect of methyl parathion and methyl paraoxon on the enzyme activity.