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Made available in DSpace on 2022-04-28T19:42:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-08-14 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Multilayered TiO2/TiO2−x/TiO2 films, deposited by twenty periodical interruptions of O2 flow during reactive sputtering deposition were submitted to photocatalytic tests and characterized. The O2 flow interruptions lasted 10 s, 38 s, 45 s, and 70 s, while the regular flow periods lasted 540 s. The photocatalytic tests were performed using UV irradiation from a mercury lamp and a solution of methylene blue dye. The best photocatalytic response was observed in samples corresponding to 10 s interruptions. The results show that the amount of degraded dye was increased by an average of 1.67 times in the interrupted flow sample as compared to the homogeneous TiO2 film deposited under similar conditions. The results show that this relatively simple deposition procedure can produce significant improvements to the photocatalytic activity of the TiO2-based catalysts. Graphic abstract: [Figure not available: see fulltext.] School of Sciences Graduate Program in Materials Science and Technology - POSMAT Universidade Estadual Paulista – UNESP Physics Department Fundamental Sciences Division – IEF Instituto Tecnológico de Aeronáutica – ITA School of Sciences Graduate Program in Materials Science and Technology - POSMAT Universidade Estadual Paulista – UNESP FAPESP: 2017/18916-2

In this study, the LED array system (UV and visible light) was established, and the theoretical light distribution of the reactor was simulated in MATLAB. The light field of the conventional light source is more uniform than that of the LED array, and the light field uniformity of the LED array can optimize by increasing the number of LED. Various combinations of light sources and catalysts were subjected to batch experiments in laboratory-scale reactors. All experiments are consistent with the Langmuir-Hinshelwood model, where k UV-LEDs array [P25-Sulfamethazine]=0.0018 min−1 and k Blue-LEDs array [Ag3PO4-Tetracycline]=0.0077 min−1. In comparison experiments, conventional light sources exhibited faster dynamics compared to LED array light sources, where k Mercury lamp [P25- Sulfamethazine]=0.0209 min−1 and k Xenon lamp [Ag3PO4- Tetracycline]=0.0221 min−1. Besides, all experiments are analyzed for electric energy per order (EEO). Specifically, the EEO value of the xenon lamp is 121 times that of the blue- LEDs array when the tetracycline concentration is 50 mg/L. The UV–vis of the catalyst is also coupled with the emission spectrum of the light source to evaluate the figures-of-merit of the system. The figures-of-merit ratio of the mercury lamp to the UV-LEDs array is 58.4, and the figures-of-merit ratio of the xenon lamp to the blue-LEDs array is 69.8. The obtained model can be applied to different reactors. This work demonstrates that the photocatalytic system driven by the LED array is superior to the conventional light source system regarding photon utilization rate and sustainability.

Phosphors emitting visible and near-infrared persistent luminescence have been extensively studied and commercialized owing to their wide applications in emergency lighting, information storage and in vivo bioimaging. However, ultraviolet (200–400 nm) persistent phosphors are rarely reported. Here, we developed a new Pr3+ activated BaLu2Al2Ga2SiO12 persistent luminescence phosphor, which could be effectively excited by a standard 254 nm mercury lamp and exhibits excellent ultraviolet (280–400 nm) persistent luminescence lasting for more than 3 h. This exciting result encouraged us to comprehensively investigate its structural information, photoluminescence and thermoluminescence properties to reveal a feasible persistent luminescence mechanism. The results show that Pr3+ ions act as both photoluminescence and persistent luminescence emitters, and the ultraviolet light emission originates from its parity allowed 4f15d1 → 4f2 inter-configurational transitions. The suitable energy location of the lowest energy 4f2 → 4f15d1 excitation transition and small Stokes shift of less than 3000 cm−1 (0.37 eV) related to the composition and crystal structure of the host lattice BaLu2Al2Ga2SiO12 ensure the occurrence of Pr3+ 4f15d1 → 4f2 transitions. Moreover, the suitable trapping levels related to Pr4+ in BaLu2Al2Ga2SiO12:Pr3+ were also investigated utilizing thermoluminescence spectra, which could be effectively filled by carriers under 254 nm light irradiation to achieve ultraviolet persistent luminescence. This study opens up new avenues for future research on ultraviolet persistent luminescence and brings new application prospects in the fields of photocatalysis and photodynamic therapy.

The photo-induced fluorescence method is often applied to determine non-native fluorescent compounds. It typically uses UV irradiation from a high pressure mercury vapor discharge lamp to create photo-induced fluorescent compounds, which are then quantified by fluorescence spectroscopy. However, these mercury lamps require a high-voltage power supply and may accidentally induce electric shocks and the release of mercury vapors. As an alternative, we have evaluated in this technical note new UV-C germicidal lamps. These lamps exhibit a higher power at 254 nm and allowed us to obtain a far greater amount of photo-induced compounds in a shorter time. For the first time, this new irradiation system has been applied for the determination of pesticides in water and has shown a significant increase in the method sensitivity. These good results allowed us to conclude that the new UV-C lamps are a relevant alternative to high pressure mercury vapor discharge lamps for use with photo induced fluorescent methods.

The photolysis of C2H2F2Br2 mixed with oxygen is studied at T = 298 K for different times of irradiating the mixture using a mercury lamp having the maximum emission at λ = 253.7 nm. The absorption spectra are recorded in the range of wavelengths of 200 to 900 nm using Specord M-40 spectrophotometer. The kinetics of the photolysis are studied monitoring consumption of the initial halon and accumulation of molecular bromine. The absorption’s cross sections are estimated for C2H2F2Br2 halon in the range of wavelengths 230 to 258 nm. A mechanism of photolysis of C2H2F2Br2 mixed with oxygen is proposed. The cross section for the dissociation of C2H2F2Br2 is determined at the wavelength of 253.7 nm. The ratio of the reaction rate constant for the C2H2F2Br radical formed during the photolysis with molecular bromine to the reaction rate constant of the same radical with molecular oxygen is estimated.

A series of photochemical experiments with sulfur dioxide were carried out using a xenon lamp (λ > 200 nm), a low-pressure mercury lamp (λ = 184.9 and 253.7 nm), and an UP-213 laser system (λ = 213 nm) as light sources. Based on the isotope data obtained for elemental sulfur (the end product of SO2 photolysis), we revealed specifics in correlations between δ34S, ∆33S, and ∆36S values depending on the spectral characteristics of the incident radiation. Our studies showed that the Archean Δ33S/δ34S and Δ36S/Δ33S ratios could be reproduced in the SO2 photolysis experiments by combining spectral composition of the radiation, the intensity of the spectral components, and the partial pressure of SO2. The results of the experiments suggest that the UV radiation with wavelengths less than 200 nm was a determining factor in the production of sulfur isotopic anomalies in the Archean atmosphere.

The yield of redox reactions (Fe2+ oxidation and Mn7+ reduction in aqueous solutions) under the action of hot plasma radiation in liquid and species formed in the region of plasma discharge was measured. The goal of the investigation is to evaluate the role of hot plasma radiation as active factor compared to species generating in discharge itself. As source of active species we studied the spark discharge in air and in nitrogen (SD50 generator), the generator of corona discharge in air and low-pressure mercury UV lamp (λ = 253.7 nm). The yield of redox reactions for all sources was determined using detecting liquids; the mechanisms of these reactions were analysed. It was shown that chain reactions do not take place. When the yields were calculated, the stoichiometry of the reactions was taken into account. An analysis of the results shows that under the action of a spark discharge generator SD50, the main active factor is radiation. The role of active species formed in discharge region not more than 15%. Under the action of a spark discharge radiation, active species first form in the sample being processed, and then interact with substances dissolved in water. There is an indirect mechanism of action. Owing of this peculiarity, the redox properties of water, activated by hot plasma radiation, are the same as direct treatment of samples to hot plasma radiation. For a corona discharge plasma and radiation from a mercury lamp, such a mechanism does not occur.

Hybrid photochemical methods are considered for water disinfection in which treatment with ultraviolet (UV) and ultrasonic (US) radiations are combined (US/UV) and applied consecutively or simultaneously; the use of catalysts is also included. The literature survey shows that inactivation of pathogenic microorganisms in aquatic media by high-frequency US (>100 kHz) has not been studied adequately, whereas only low-frequency (

Direct photolysis of the emerging contaminant 2-(thiocyanomethylthio) benzothiazole (TMCTB) was performed in aqueous solution at different concentrations with high-pressure mercury lamp (5.0, 8.0, 13.0, 16.0, 20.0, 23.0, 27.0, 35.0, 40.0, 45.0, and 50.0 mg L− 1) and with natural sunlight radiation (6.0, 30.0, and 60.0 mg L− 1). TCMTB underwent rapid degradation by direct photolysis with a high-pressure mercury lamp in aqueous solutions, with 99% removal after 30 min at all concentrations studied. For sunlight photolysis, TCMTB degradation was observed with 96%, 81%, and 64% removal for initial concentrations of 6.0, 30.0, and 60.0 mg L− 1, respectively, after 7 h of exposure to sunlight. The degradation of TCMTB in lab-scale wastewater had kinetic constant and t1/2 in the same order when compared to the photodegradation of TCMTB in aqueous solutions. In addition, the results showed that photolysis with a high-pressure mercury lamp and sunlight were governed by the same kinetic order, however the kinetic parameters showed that degradation with sunlight was 40 times slower than photolysis with the mercury lamp. Twelve transformation products (TP) were identified, and eight of the TP have not been described in the literature. Furthermore, prediction of toxicity with ECOSAR software was carried out for fish, daphnids, and green algae species. It showed that photolytic treatment is efficient for reducing the toxicity of the compound, since the degradation formed compounds with lower toxicity than the primary compound. In conclusion, this study suggests that photolysis is an efficient way to remove the studied contaminant, and it highlights the potential of this technique for the degradation of emerging contaminants in industrial wastewater treatment plants.

Objective: The aim of the method was to develop a novel, simple and rapid fluorometric method determination of Amiloride (AMD) in pure form and pharmaceutical drugs via fluorescence measurements. Methods: The method depends on fluorescence quenching of 2H-chromene azo dye (2-(4-nitrophenyl)-N-(4-(phenyldiazenyl)-2H-chromen-4-amine) upon adding Amiloride (AMD) using homemade ISNAG 2 X 90° multi solar cell via low-pressure mercury lamp at two significant wavelengths 184.9 and 253.7 nm combined with continuous flow injection analysis. Results: Under the optimized conditions, the fluorescence quenching linear working range and percentage linearity (r2%) was (0.03-8 mmol/l) and 98.78 %, respectively. The suggested method was effectively applied to the determination of AMD in two different pharmaceutical drugs and compared with the classical method (UV-vis spectrophotometry at λ=540 nm). Conclusion: The proposed and established method is simple, direct, and efficient. The statistical comparison results using a t-test at 95% confidence interval that was applied to compare the new and classical method showed there are no significant differences between the two methods.

In this work, the effect of the methods of synthesis on the phase composition and photocatalytic properties of composites formed in the section of (SrO)0.2(Bi2O3)0.8–BiFeO3 is studied on the examples of the decomposition reactions of methylene orange (MO). The studied compositions have the MO degradation degree ranging from 30 to 62% (C0 = 20 mg/L, catalyst loading of 30 mmol/L) under irradiation for 3 h with a fluorescent mercury lamp. The band gap estimated by the Kubelka–Munk function is lower than 2.6 eV for the studied compositions. This indicates the possibility of their application as photocatalysts of the visible range.

Optical mapping is a fluorescence-based physiological method to image spreading of action potential in excitable tissues, such as the heart and central nervous system. Because of the requirements for high speed imaging in low light conditions, highly sensitive high-speed cameras together with an optical system with maximum photon efficiency are required. While the optimization of these two components is relatively straightforward, the choice of the perfect light source is less simple; depending on the other (usually fixed) components, various parameters may acquire different weight in decision-making process. Here we describe the rationale for building an optical mapping setup and consider the relative advantages and disadvantages of three different commonly available light sources: mercury vapor lamp (HBO), xenon lamp (XBO), and light emitting diode (LED). Using the same optical system (fluorescence macroscope) and high-speed camera (Ultima L), we have tested each of the sources for its ability to provide bright and even illumination of the field of view and measured its temporal fluctuations in intensity. Then we used each in the actual optical mapping experiment using isolated, perfused adult mouse heart or chick embryonic heart to determine the actual signal to noise ratio at various acquisition rates. While the LED sources have undergone significant improvements in the recent past, the other alternatives may still surpass them in some parameters, so they may not be the automatic number one choice for every application.

The UV-C light emitting diode (LED) has shown numerous advantages over the traditional UV mercury lamp for water sterilization applications. Multi-chip LED array was used to provide sufficient UV fluence for bacteria inactivation in limited time. According to the point light source characteristic of LEDs, the arrangement of LEDs in the batch reactor is crucial to optimize the inactivation efficiency. In this study, the inactivation of

The oxidation of methyl orange (MO) under the influence of radiation from spark discharge plasma in air and a low-pressure mercury lamp is studied. Two modes of sample processing are compared: the action of radiation on an aqueous solution of MO (mode 1, direct action) and the action of radiation on water, after which the water is mixed with a solution of MO (mode 2, indirect action). The radiation energy of the mercury lamp is ten times greater than the energy of radiation from spark discharge, but the yield of MO oxidation under the action of the mercury lamp is 100 times lesser than the yield under the action of spark discharge radiation. This is due to the difference in the spectrum of radiation and the operating regime (continuous and pulsed). The yields of MO oxidation under the action of spark discharge plasma radiation for modes 1 and 2 are the same and amount to 1.2–1.3 1/(100 eV). This means that active species are first produced in water and then interact with the dissolved substance, indirect mechanism takes place. Under the action of radiation from a mercury lamp, the oxidation yield in mode 2 is zero within the limits of experimental errors, direct mechanism takes place.

In the present study, advanced oxidation treatment, the TiO2 /UV/H2O2 process was applied to decolorisation of the reactive yellow dyes in aqueous solution. The UV radiation was carried out with a 6 W low-pressure mercury lamp. The rate of color removal was studied by measuring the absorbency at a characteristic wavelength. The effects of H2O2 dosage, dye initial concentration and pH on decolorisation kinetics in the batch photoreactor were investigated. The highest decolorisation rates were observed (98.8) at pH range between 3 and 7. The optimal levels of H2O2 needed for the process were examined. It appears that high levels of H2O2 could reduce decolorisation by scavenging the *OH. The color degradation rate decreases as the dye concentration increases. The rate coefficient (k=0.0319 min-1) of degradation, follows the pseudo-first-order kinetics.

The paper presents the results of studying the characteristics of a slow ionization wave (IW) arising at the initial stage of breakdown in a long discharge tube under reduced pressure. The discharge tube is a Philips TUV-30W mercury lamp with an electrode spacing of 80 cm and an inner diameter of 23 mm. The tube is filled with argon at a pressure of 2–4 Torr (nominal data) and mercury vapor. One of the electrodes is grounded, and, to the second one, positive or negative voltage pulses with an amplitude of 2 kV, a leading edge duration of ≈0.5 μs, and a repetition frequency of 1 Hz are applied. The IW velocity and the time dependence of the intensities of the Ar, Ar+, and Hg lines in the IW at different distances from the high-voltage electrode are measured. It is shown that the velocity of a positive IW (3 × 107–5 × 107 cm/s) is higher than the velocity of a negative IW (1 × 107–1.8 × 107 cm/s). The magnitude of the electric field in the front of an IW is evaluated from the comparison of the measured and calculated intensity ratios of the Ar, Ar+, and Hg lines. It is shown that, in a positive IW, the magnitude of the reduced electric field (260–450 Td) is noticeably larger than in a negative one (120–165 Td).

Photolithography is the prevalent microfabrication technology. It needs to meet resolution and yield demands at a cost that makes it economically viable. However, conventional far-field photolithography has reached the diffraction limit, which imposes complex optics and short-wavelength beam source to achieve high resolution at the expense of cost efficiency. Here, we present a cost-effective near-field optical printing approach that uses metal patterns embedded in a flexible elastomer photomask with mechanical robustness. This technique generates sub-diffraction patterns that are smaller than 1/10th of the wavelength of the incoming light. It can be integrated into existing hardware and standard mercury lamp, and used for a variety of surfaces, such as curved, rough and defect surfaces. This method offers a higher resolution than common light-based printing systems, while enabling parallel-writing. We anticipate that it will be widely used in academic and industrial productions., Photolithography is an established microfabrication technique but commonly uses costly shortwavelength light sources to achieve high resolution. Here the authors use metal patterns embedded in a flexible elastomer photomask with mechanical robustness for generation of subdiffraction patterns as a cost effective near-field optical printing approach.

A photochemical treatment with UV multi-wavelength irradiation was applied to investigate the degradation of the saponins mixture obtained from alfalfa leaves. The photo-degradation was studied in an aqueous solution at a pH range of 4–7 and temperature range of 20–80 °C. The samples were irradiated for 80 min using a mid-pressure mercury lamp with emission wavelengths between 250 and 740 nm. The dependence of the absorbed radiation on the concentration of alfalfa saponins was evaluated, and a linear dependence was found for the range of concentrations experimented throughout the photo-degradation. The alfalfa saponins mixture absorbed radiation between 470 and 610 nm with a maximum absorption peak at 543 nm. This means that any lamp emitting within this wavelength range could produce some degree of photo-degradation. A reaction mechanism was proposed, matching the experimental pseudo-first-order kinetic model that best fitted the evolution of the saponins mixture concentration. The photo-degradation rate was found to increase with increasing temperature and decreasing pH value, causing a reduction of 80% in the concentration of the alfalfa saponins mixture after 80 min at pH 4 and 80 °C.

A novel series of naphthodiazepines 4a-e, 6 were synthesized through the reaction of 1,8-diaminonaphthalene 1 with either hydrazonoyl chlorides 2a-e, or bis-hydrazonoyl chloride 5, respectively. Moreover, new derivatives of thiazinoperimidine 9, triazoloperimidine 13 , and thiazoloperimidines 14,17 were produced upon the interaction of 1H-perimidine-2-thiol 7 with the reagents; epichlorohydrin, hydrazonoyl chloride 10, bis-hydrazonoyl chloride 5, and α-chloroacetoacetanilide 15, respectively. Additionally, the irradiation of 1,8-diaminonaphthalene 1 was accomplished at λ > 313 nm using a high-pressure mercury lamp in the presence of oxygen. All the products were characterized using spectroscopic and analytical techniques

The inactivation or airborne pathogens inside closed spaces is a critical issue that raised overwhelmingly during the current SARS-CoV 2 pandemic. Among the different technologies to achieve air sanification, the ultraviolet germicidal irradiation is a trending technique, also due to the fast development of more and more effective ultra-violet LED sources, that are expected to replace the mercury vapor lamps in the next few years. The positioning of LEDs inside cavities with highly reflective surfaces permits an enhancement of the internal irradiance and the development of compact devices. Optical simulations, by means of ray tracing, are fundamental, since an accurate irradiance estimation in presence of multiple internal reflections, scattering, light leaks outside the cav-ity and the sources angular emission distribution is not possible with only analytical calculations. Ray tracing permits to model the spatial irradiance inside the cavity by varying the components parameters to maximize the inactivation rate as a function of the air flow field. We discuss, on the basis of the experience on several related projects, the advantages of using the numerical approach to simulate these devices, focusing the attention onto the critical parameters which must be controlled to retrieve a reliable estimation of the system performance.

Droplet digital polymerase chain reaction (ddPCR) is an effective technique, with unparalleled sensitivity, for the absolute quantification of target nucleic acids. However, current commercial ddPCR devices for detecting the gene chip are time consuming due to complex image stitching. To address this issue, we propose a universal concentration determination system and realize one-time gene chip imaging with high resolution. All the functional units are controlled by self-developed software using the PyQt5 module in Python. Without stitching technology, images of the ddPCR chip (28 mm × 18 mm) containing 20 000 independent 0.81 nL micro chambers can be obtained in less than 15 seconds, which saves about 165 seconds. A white laser light source (2 mW cm-2) was employed as a substitute for the mercury lamp. Its wavelength matches well with typical fluorescent dyes (e.g., HEX, ROX and Cy5), and thus it can strengthen the fluorescence intensity for weak signals. The results also demonstrated that the correlation coefficient for the measured concentration and theoretical value was above 99%, by testing the ddPCR products with COVID-19 virus. Such a system can greatly reduce the time required for image acquisition and DNA concentration determination, and thus is able to speed up the lab-to-application process for ddPCR technology.

This paper presented a facile and efficient HPTLC method for quantifying riboflavin fortification in rice noodle that was a staple food popular in Asian countries. After high-throughput separation on silica gel plates with methanol/ethyl acetate/triethylamine (3/7/1, v/v/v) as the mobile phase, the obtained results were analyzed by fluorescence densitometry (mercury lamp, 360 nm excitation wavelength in combination with K400 optical filter). Quantification in this way offered high linearity (R2 = 0.9998 within 10–80 ng/band) and precision (RSD

The optical schemes and characteristics of atomic absorption Hg0 analyzers based on the Zeeman effect and a low-pressure capillary mercury lamp, as well as on 190 fm linewidth UV dye laser systems have been studied in detail. The method of evaluating the limit of detection (LOD) of atomic absorption analyzers is proposed. The characteristics of modern ultra-narrowband sensors and sources of UV radiation are analyzed. The efficiency of using new thermal ultrasonic sensors as optical power detectors in the atomic absorption analyzer is discussed. Technical characteristics and reliability of such sensors are compared with all known thermal sensors. The main physical and technical limitations that have a negative effect on the sensitivity and miniaturization of thermal ultrasound sensors are presented. The study shows that such thermal sensors have low sensitivity and accuracy, which makes their use in portable express analyzers of background mercury impractical. The evaluation results prove that the analyzers which use a transverse magnetic field for splitting the lamp emission line also cannot register background mercury concentration. This fact is explained by the low signal-to-noise ratio (SNR) of the discharge low-pressure UV lamp operating in a continuous mode and by the absorption of forbidden oxygen lines by the reference optical signal. The estimation results shown that the portable Hg0 analyzers based on UV dye laser systems can reach the LOD $\text{m}^{3}$ . Thus, the main stage in the design of the portable express background mercury analyzers is a measurement of the SNR of UV sources and sensors.

Solution-processed metal oxide semiconductors have superior electron mobility and stability than solution-processed organic semiconductors. However, their fabrication requires a very-high-temperature and long-time annealing process. In this study, we utilized deep ultraviolet (DUV) light to decrease both the temperature and time of the annealing process. High external energy is required to break the organic bonds in a metal oxide film, which is generally supplied by a high-temperature annealing process carried out for a long duration. Alternatively, the required high energy can be supplied more efficiently by irradiating the metal oxide film with DUV light for a shorter duration. In this work, we used DUV light whose peaks at 172 nm instead of the generally used mercury lamp, peaking at 254 and 185 nm. Owing to this difference, thin film transistors (TFTs) could be fabricated on silicon wafers at a lower temperature and shorter duration as compared to the conditions used in previous studies. Various conditions, such as the heating temperature, duration of DUV irradiation, and N2 flow rate, were optimized to control the heating temperature so as to achieve a mobility of 4.44 cm2/V·s and on–off ratio of 2 × 107, which are much higher than those of a transistor annealed at 300 °C for 30 min (mobility, 1.31 cm2/V·s and on–off ratio, 7 × 105).

A large number of fluorinated chemicals have been synthesized and used worldwide because of their unique properties. However, because of the strong C–F bond, fluorinated chemicals are not decomposed in nature. Herein, the activity of gallium oxide toward the degradation of trifluoromethyl benzoic acid in aqueous media was examined under UVC radiation by using a low-pressure mercury lamp as the light source. The degradation process was monitored by HPLC, UV–Vis spectroscopy and TOF-MS techniques, which permitted some intermediates to be identified. The defluorination efficiency was greater under a nitrogen atmosphere than in air, with the para-isomer (4-(trifluoromethyl)benzoic acid) being more prone to degradation (ca. 90%). The degradation mechanism was proposed on the basis of the theoretical calculation on the electron density and the intermediate analysis.

The mixture of argon and mercury vapor with temperature-dependent composition is used as the background gas in different types of gas discharge illuminating lamps. The aim of this work was to develop a model of the low-current discharge in an argon-mercury mixture at presence of a thin insulating film on the cathode and to investigate the influence of film on the discharge ignition voltage at low ambient temperatures. When discharge modeling, we used the obtained earlier expression which describes dependence of the mixture ionization coefficient on temperature. When there was a thin insulating film on the cathode the model took into account that positive charges are accumulated on its surface during the discharge. They generate an electric field in the film sufficient for the field emission of electrons from the metal substrate of the electrode into the insulator and some of them can overcome the potential barrier at the film outer boundary and go out in the discharge volume improving emission characteristics of the cathode.Calculations showed that at a temperature decrease the electric field strengthes in the discharge gap and the voltage in it are increased due to reduction of the saturated mercury vapor density in the mixture followed by the decrease of its ionization coefficient. Existence of a thin insulating film on the cathode surface results in an increase of the cathode effective secondary electron emission yield which compensates the reduction of the mixture ionization coefficient value.The results of discharge characteristics modeling demonstrate that in case of the cathode with an insulating film the discharge ignition becomes possible at a lower inter-electrode voltage. This ensures outdoor mercury lamp turning on at a reduced supply voltage and increases its reliability under low ambient temperatures.

A new method has been proposed for photochemical reduction of silver cations into nanoparticles (NPs) of varying morphologies in aqueous solutions of sodium citrate. The silver NPs were prepared from silver nitrate by the citrate method in aqueous solutions at room temperature by irradiating with light of a high-pressure mercury lamp DRK 120 and BUV 15 lamp. The conversion of silver cations into the final silver NPs of varying morphologies is determined by the concentration of the initial components of the irradiated mixture, light wavelength, and exposure time.

The recent development of hyperspectral imaging and pattern recognition can find wide applications in recognition of explosive materials. This study reports on novel technique for remote sensing of explosive material using hyperspectral imaging. Common explosive materials including TNT, RDX, and HMX were illuminated with multi-spectral line sources at 457, 488, and 514 nm with energy 10 mW. Furthermore, mercury lamp was employed to represent the outdoor environment. The reflected and emitted light of each tested explosive material was collected using hyperspectal camera to generate cubic images. The variation of reflected energy as function of wavelength was employed to generate characteristic spectrum of each explosive material. This approach offered standoff imaging of all concealed explosive materials at 569.6, 641.2, and 743 nm. Nitramine explosives (RDX and HMX) were distinguished from TNT at 395.5, and 626.2 nm. HMX was distinguished from RDX at 771 nm. A novel digital signal processing algorithm was employed for TNT recognition through normalization of reflectance spectral images with subsequent subtraction. Where, spectral image in UV band (395.52 nm) was subtracted from spectral image in visible band (569.6 nm). This novel approach offered discrimination of TNT from all other explosive materials. Edge detection and noise removal was performed using two-D Hilbert transform. In conclusion, we report on novel, non-invasive, non-contact technique for remote recognition of hidden explosive material.

Addition of :P[triple bond, length as m-dash]C-tBu to the NHC-coordinated trisilacyclopropylidene Si3Mes4NHCiPr2Me2 afforded a heavier analogue of a bicyclo[2.1.0]pentane, a so-called "housane", that rearranges under irradiation with a high-pressure mercury lamp or at 60 °C to an NHC-stabilized cyclopentenyl anion isomer with a three-center four-electron (3c-4e) π-bond.

Biofilms are ubiquitous in aquatic environment. While so far, most of the ultraviolet (UV) disinfection studies focus on planktonic bacteria, and only limited attention has been given to UV irradiation on biofilms. To enrich this knowledge, the present paper reviews the up-to-date studies about applying UV to control biofilms in water and wastewater infrastructure. The development of UV light sources from the conventional mercury lamp to the light emitting diode (LED), and the resistance mechanisms of biofilms to UV are summarized, respectively. Then the feasibility to control biofilms with UV is discussed in terms of three technical routes: causing biofilm slough, inhibiting biofilm formation, and inactivating bacteria in the established biofilm. A comprehensive evaluation of the biofilm-targeted UV technologies currently used or potentially useful in water industry is provided as well, after comparative analyses on single/combined wavelengths, continuous/pulsed irradiation, and instant/chronic disinfection effects. UV LEDs are emerging as competitive light sources because of advantages such as possible selection of wavelengths, adjustable emitting mode and the designable configuration. They still, however, face challenges arising from the low wall plug efficiency and power output. At last, the implementation of the UV-based advanced oxidation processes in controlling biofilms on artificial surfaces is overviewed and their synergistic mechanisms are proposed, which further enlightens the prospective of UV in dealing with the biofilm issue in water infrastructure.

The addition of contaminated powdered spices and seasonings to finished products which do not undergo further processing represents a significant concern for food manufacturers. To reduce the incidence of bacterial contamination, seasoning ingredients should be subjected to a decontamination process. Ultraviolet light emitting diodes (UV-LEDs) have been suggested as an alternative to UV lamps for reducing the microbial load of foods, due to their increasing efficiency, robustness and decreasing cost. In this study, we investigated the efficacy of UV-LED devices for the inactivation of four bacteria (Listeria monocytogenes, Escherichia coli, Bacillus subtilis and Salmonella Typhimurium) on a plastic surface and in four powdered seasoning ingredients (onion powder, garlic powder, cheese and onion powder and chilli powder). Surface inactivation experiments with UV mercury lamps, UVC-LEDs and UVA-LEDs emitting at wavelengths of 254 nm, 270 nm and 365 nm, respectively, revealed that treatment with UVC-LEDs were comparable to, or better than those observed using the mercury lamp. Bacterial reductions in the seasoning powders with UVC-LEDs were less than in the surface inactivation experiments, but significant reductions of 0.75–3 log10 colony forming units (CFU) were obtained following longer (40 s) UVC-LED exposure times. Inactivation kinetics were generally nonlinear, and a comparison of the predictive models highlighted that microbial inactivation was dependent on the combination of powder and microorganism. This study is the first to report on the efficacy of UV-LEDs for the inactivation of several different bacterial species in a variety of powdered ingredients, highlighting the potential of the technology as an alternative to the traditional UV lamps used in the food industry.

Mercury discharge lamps are often used because of their high efficiency, however, the usage of mercury lamps will be restricted or forbidden for safety and environmental purposes. Finding alternative solutions to suppress mercury is of major interest. The aim of this work is to increase the luminous efficacy of a commercial-free mercury flat dielectric barrier discharge lamp (Planilum, St Gobain) in order to reach the necessary conditions for the lamp to be used as a daily lighting source. The lamp is made of two glass plates separated by a gap of 2 mm. The gap is filled by a neon xenon mixture. The external electrodes made of transparent ITO (indium tin oxide) are deposited on the lamp glass plates. The electrical signal applied to the electrodes generates a UV-emitting plasma inside the gap. Phosphors deposited on the glass allow the production of visible light. The original electrode geometry is plane-to-plane, this induces filamentary discharges. We show that changing the plane-to-plane geometry to a coplanar geometry allows the plasma to spread all over the electrode surface, and we can reach twice the efficacy of the lamp (32 lm/W) as compared to the original value. Using this new electrode geometrical configuration and changing the electrical signal from sinusoidal to a pulsed signal greatly improves the visual uniformity of the emitted light all over the lamp. Electrical and optical parametric measurements were performed to study the lamp characteristics. We show that it is possible to develop a free mercury lamp with an efficacy compatible with lighting purposes.

Light is one of the most adverse factors for bamboo deterioration and causes surface degradation and discoloration. The study was carried out to initiate efficient and effective photodiscoloration to modify and enrich bamboo colors that may be applied to bamboo dyeing. Different types of bamboo samples commonly used in the industry were studied experimentally under two types of ultraviolet (UV) light. Effects of light sources, radiation time, and distances on discoloration and discoloration mechanism were systematically studied. For both UV 313 and high-pressure mercury light, the bamboo surface turned red-yellow, and color parameters including Δ E , Δ a , Δ b , and C rapidly increased first and then stabilized for long time, while Δ L showed a similar trend, except for the final decrease. Compared with UV 313, high-pressure mercury lamp light was highly efficient and took less time to induce discoloration. Heat treatments darkened the bamboo color and slowed down photodiscoloration, and the higher temperature led to more photostability. The color change of bamboo scrimber under UV radiation was less and slower than that of untreated bamboo due to high density and heat treatment, and the dark carbonized scrimber changed less than that of the light carbonized scrimber. Relatively high contents of isovanillin, syringaldehyde, β-hydroxypropiovanillone, p-hydroxybenzaldehyde, and syringic acid were identified by GC-MS, and syringaldehyde, 2,6-dimethylbenzoquinone, and 3-hydroxy-4-methoxybenzoic acid were identified by HPLC-MS from a bamboo discoloration layer after high-pressure mercury lamp radiation. These products all contained a conjugated double bond and were conjectured to be degraded from lignin or aromatic extracts. Particularly, 2,6-dimethylbenzoquinone which contained a cyclohexenedione structure without benzene rings, was more chemically stable than other conjugated double bonds with benzene rings, and was supposed to be the final product (chromogenic group) during bamboo photodegradation. Untreated or light-colored bamboo under high-energy UV light initiated highly efficient and effective photodiscoloration, and UV light is recommended for being applied to industrial bamboo dyeing. Compared with traditional chemical dyeing, the photoinduced dyeing method has no chemical addition and is easy to operate and environmental-friendly.

The high pressure mercury discharge was recognized as a possible source of light as early as 1906 by Kuch and Retachinsky, who made studies of the discharge. In the early 1950s, improved seals, emission materials and phosphors were developed for the high pressure mercury vapor lamp, which greatly increased lamp life, improved color and provided better lumen maintenance. The sodium radiation at low pressure consists of two narrow resonance lines at 589.0 and 589.6 nanometers. Mercury and sodium, when mixed together, form an amalgam in which the vapor pressure of each is less than it would be as separated elements. The high pressure sodium (HPS) lamp arc tubes evolved in their design with changes that reduced the sodium losses through the seal, improved the purity and consistency of the sodium amalgam dosage, improved the emission material, altered the design of the electrode and optimized the arc tube dimensions. HPS lamps are most generally used in outdoor lighting applications.

Decolorization of synthetic azo Reactive Red 120 (RR120) dye wastewater via UV/Fe+3 process was investigated. A preliminary study was conducted to understand the effect of various process variables like oxidant dose Fe+3 (0.25–2.75 mM)), initial dye concentration (100–200 mg/L), time (0–35 min), initial pH (1–11) on the decolorization of RR120. Response surface methodology (RSM) was employed to assess individual and interactive effects of critical process parameters on treatment performance in terms of colour removal efficiency. The photo-degradation of RR120 was investigated in a laboratory-scale batch photo-reactor equipped with low-pressure mercury lamp. Optimized process conditions for UV/Fe+3 treatment of RR120 suggested by RSM are Fe3+ = 2.35 mM, pH = 3.6, Initial dye concentration = 170 mg/L and reaction time = 55 min. Under these conditions, 92% colour removal was actually observed which is found to be very close to prediction given by fitted model. Treatment cost of UV/Fe+3 process was ~4 Rs/L.

SARS-CoV-2 is a single-stranded RNA virus classified in the family Coronaviridae. In this review, we summarize the literature on light-based (UV, blue, and red lights) sanitization methods for the inactivation of ssRNA viruses in different matrixes (air, liquid, and solid). The rate of inactivation of ssRNA viruses in liquid was higher than in air, whereas inactivation on solid surfaces varied with the type of surface. The efficacy of light-based inactivation was reduced by the presence of absorptive materials. Several technologies can be used to deliver light, including mercury lamp (conventional UV), excimer lamp (UV), pulsed-light, and light-emitting diode (LED). Pulsed-light technologies could inactivate viruses more quickly than conventional UV-C lamps. Large-scale use of germicidal LED is dependent on future improvements in their energy efficiency. Blue light possesses virucidal potential in the presence of exogenous photosensitizers, although femtosecond laser (ultrashort pulses) can be used to circumvent the need for photosensitizers. Red light can be combined with methylene blue for application in medical settings, especially for sanitization of blood products. Future modelling studies are required to establish clearer parameters for assessing susceptibility of viruses to light-based inactivation. There is considerable scope for improvement in the current germicidal light-based technologies and practices.

Aims To obtain quantitative efficacy data of two ultraviolet light (UVC) technologies for surface inactivation of Bacillus anthracis Ames and Bacillus atrophaeus spores. Methods and results Spores were deposited onto test coupons and controls of four different materials, via liquid suspension or aerosol deposition. The test coupons were then exposed to UVC light from either a low-pressure mercury vapor lamp or a system comprised of light emitting diodes, with a range of dosages. Positive controls were held at ambient conditions and not exposed to UVC light. Following exposure to UVC, spores were recovered from the coupons and efficacy was quantified in terms of log10 reduction (LR) in the number of viable spores compared to that from positive controls. Conclusions Decontamination efficacy varied by material and UVC dosage (efficacy up to 5·7 LR was demonstrated). There was no statistical difference in efficacy between the two species or between inoculation methods. Efficacy improved for the LED lamp at lower relative humidity, but this effect was not observed with the mercury vapor lamp. Significance and impact of the study This study will be useful in determining whether UVC could be used for the inactivation of B. anthracis spores on different surface types.

This research designed optical sensors using mercury lamp of 160W. These sensors provided voltage and current output. The design of optical sensors used the organic based material,i.e. dye carotene and phycocyanin. Fabrication of optical sensor in this research used spin coating deposition method. Based on the results of absorbance test, dye carotene had the largest absorption of light of 2.882 (a.u). Dye phycocyanin at length had the largest absorption of light of 2.787 (a.u). Combination between dye carotene and phycocyanin, for a 3: 1 (Carotene: Phycocyanin) ratio had a waveform like a dye carotene with a peak of 2.587 (au), whereas for 1: 3 had a waveform like phycocyanin with a peak of 2,279 (au). But, sample 1: 1 ratio had decrement the light absorbance rate with peaks of 1.183 (au). At the voltage testing result, combination of phycocyanin: carotene (1:3) had the best linearity. The response time of dye 3:1 (phycocyanin: carotene), 1:1, 1:3, phycocyanin, and carotene were 6.72 s, 2.469s, 1.171s, 2.66s and 7.01s respectively.

A vacuum-ultraviolet/ultraviolet (VUV/UV) mercury lamp was found to be a highly efficient radiation source for UV-based advanced oxidation processes (AOPs). If this lamp could enhance the UV/H2O2 process, it would be very attractive. Hence, we have investigated sulfamethazine (SMN) degradation by the VUV/UV/H2O2 process based on a bench-scale mini-fluidic VUV/UV photoreaction system (MVPS), a pilot reactor, and a model analysis. At high [SMN]0 in the MVPS, the apparent SMN degradation rate constant ( k'app) increased with increasing H2O2 dose, while at low [SMN]0, k'app decreased with increasing H2O2 dose; this behavior was unexpected. Meanwhile, at low [SMN]0 in a pilot reactor, H2O2 induced just a slight enhancement in the VUV/UV/H2O process. A numerical simulation of the process suggested that for an integrated AOP (i.e., VUV/UV/H2O2) consisting of various component AOPs, H2O2 could inhibit the component AOPs with HO* that did not originate from H2O2 (e.g., VUV photolysis of water). The apparent H2O2 role in the integrated AOPs was dependent on the contribution comparison between component AOPs that involved HO* that did or did not originate from H2O2. These results revealed important information regarding the application of the VUV/UV/H2O2 process in water treatment.

Diols and primary alcohols were subjected to the action of a system FeCl3–NaNO2/O2 (air) under mercury lamp irradiation to synthesize unsubstituted and 2-methyl-1,3-dioxacyclanes: 1,3-dioxolane, 1,3-dioxepane, 1,3-dioxocane, 2-methyl-1,3-dioxolane, 2-methyl-1,3-dioxepane, 2-methyl-1,3-dioxocane. The probable mechanism of the photocatalytic synthesis of 1,3-dioxacyclanes was described by an example of 2-methyl-1,3-dioxolane.

Morphology-retained solid-state photoconversion of anthracene (AN) to 9,10-anthraquinone (PC-ANQ) and dipara-anthracene (PC-DPA) was accomplished by irradiating mercury lamp light to plate-shaped AN single crystal in oxygen and argon atmosphere, respectively. The photoconverted crystals retained the original plate shape morphology of the starting AN crystal, whereas the emission profile and crystal structure were significantly changed. The electrical conductivity of PC-ANQ crystal is 5 orders of magnitude greater than that of the starting AN crystal, whereas the PC-DPA crystal exhibits a decreased conductivity. The AN/PC-ANQ/PC-DPA heterostructures with smooth interface were successfully obtained by inducing the photoconversion only at the desired area.

This study compared the inactivation efficacy and performance of UV-LEDs emitting at 259, 268, 275, 289, and 370 nm against a low pressure mercury lamp at 253.7 nm for the foodborne pathogens, E. coli, Listeria and Salmonella. Action spectra were determined for three pathogenic and three non-pathogenic strains and compared with UV absorbance of their bacterial DNA. The lethality of UV wavelengths correlated with bacterial DNA absorbance. At an equivalent UV dose (7 mJ·cm−2), UV-LEDs emitting at 259 and 268 nm achieved the highest log count reductions out of the tested wavelengths. Refrigeration (4 °C) increased irradiance of the 268 nm UV-LEDs while not affecting reduction of Listeria compared to 25°C. Combining 259 and 289 nm UV-LED wavelengths at an equivalent UV dose had a synergistic effect on reduction of E. coli and Listeria, yielding a 1.2 and 0.6 log higher reduction, respectively, than the expected additive effect. Industrial relevance UV-LED treatment at 259, 268, and 275 nm can either equal or, in most cases, surpass the inactivation efficacy of traditional LPM lamps at 253.7 nm. Further, the determined action spectra can be used to identify the optimum inactivation wavelength for common foodborne pathogens and hence increase processing efficiency. In some cases, inactivation efficacy can be improved by combining UV wavelengths in order to achieve a synergistic effect. The effectiveness of UV-LED treatment at refrigeration temperatures validates their use in cold environments. Overall, UV-LEDs have strong potential within the food industry due to their advantages and possibilities for incorporation into a wide variety of treatment systems.

The vacuum-ultraviolet/ultraviolet/chlorine (VUV/UV/chlorine) process, with a VUV/UV mercury lamp used as the light source, was found to be a highly efficient advanced oxidation process (AOP) in a previous study. Hence, its application feasibility for trace organic pollutant removal from drinking water becomes attractive. In this work, a bench-scale mini-fluidic VUV/UV photoreaction system was used to determine the degradation kinetics of sulfamethazine (SMN), a model sulfonamide antibiotic frequently detected with trace levels in aquatic environments. Results indicated that SMN (0.1 mg L–1) could be degraded rapidly by VUV/UV/chlorine, and a synergism was observed between the VUV/UV and UV/chlorine processes. Photon-fluence based rate constants of SMN degradation were determined to be 6.76 × 103 and 8.51 × 103 m2 einstein–1 at chlorine doses of 0.05 and 0.5 mg L–1, respectively. The presence of natural organic matter in real waters significantly inhibited SMN degradation. In addition, pilot tests were co...

The formation of hydrogen peroxide in bidistilled water under the influence of UV-C radiation from a DKB-9 low-pressure mercury lamp has been studied. The yield of hydrogen peroxide was (1 ± 0.2) × 10−7 mol (L s)−1. The wavelengths of radiation under the influence of which the formation of H2O2 is possible have been estimated. It has been assumed that the intermediate product of the reaction is the HO2./O2.-radical. To identify it, oxidation–reduction reactions in aqueous solutions containing Fe2+, Fe3+, and I− ions at pH values from 0.8 to 8.1 have been studied. The quantum yield of HO2. radicals in an acidic medium under the influence of radiation from the mercury lamp is 0.015 ± 0.005.

UV and IR photochemistries of malonaldehyde, the simplest molecule exhibiting an intramolecular proton exchange, have been studied in four cryogenic matrices at 4.3 K, N2, Ne, Ar, and Xe. Samples have been irradiated using a UV and IR OPO type tunable laser, and with a broad band UV mercury lamp. UV and IR spectra have been recorded and compared with theoretical calculations carried out at the SAC–CI/6-31++G(d,p) (UV transitions) and B3LYP/6-311++G(2d,2p) (IR spectra) levels of theory. After deposition, the intramolecularly H-bonded form is found exclusively, while several open forms are formed upon UV irradiation. These open forms show ability to interconvert upon UV irradiation too. Some of them are also able to isomerize upon selective IR irradiations. The whole set of results allowed us to identify seven isomers among the eight postulated. The photodynamics of the electronic relaxation of malonaldehyde have also been investigated. By following the decay or rise of suited specific vibrational bands in ...

A photocatalytic reactor using an ozone-generating mercury vapor lamp with the capability to simultaneously utilize the ozone internally generated from the lamp was fabricated. The reactor included a microbubble-generating mechanism to facilitate the dissolution of ozone and oxygen in the reaction liquid. Photocatalytic and photolytic degradation were investigated using two types of mercury vapor lamps: an ozone-generating lamp emitting at both 254 nm and 185 nm as well as a germicidal lamp emitting only at 254 nm. The roles of ozone, 254 nm light and 185 nm light under the degradation of methyl orange were investigated. In particular, the mineralization of methyl orange in different processes, namely pure ozonation, photolysis under an ozone-generating lamp with or without the assistance of ozone, photolysis under a germicidal lamp, TiO2 photocatalysis under an ozone-generating lamp with or without the assistance of ozone and TiO2 photocatalysis under a germicidal lamp, were analyzed with the chemical oxygen demand and UV–visible absorption measurements.

Photolithography based on optical mask is widely used in academic research laboratories due to its low cost, simple mechanism, and ability to pattern in micron-sized features on a wafer-scale area. Because the resolution is bound by diffraction limits of the light source, nanoscale patterning using photolithography requires short-wavelength light source combined with sophisticated optical elements, adding complexity and cost. In this paper, a novel method of subwavelength patterning process using conventional i-line mercury lamp is introduced, without the use of such advanced optical tools. The method utilizes the re-entrant geometry of image reversal photoresist produced from the developing process, where a secondary mask is generated by isotropically depositing a metal layer to cover the re-entrant profile of the photoresist. Removing the photoresist by applying ultrasonic vibrations in acetone bath uniformly cracks the metal layer at the sidewalls of the re-entrant profile, exposing the substrate with a reduced feature size. The width of the initial mask pattern can be reduced by 400 nm in a controlled manner, regardless of the original width choice. As a result, the method is shown to achieve sub-100 nm scale linear patterns compatible for both subsequent deposition process and dry-etching process. Our approach is applicable to various shapes of the patterns and can be used in electronic device fabrication requiring nanoscale lithography patterning, such as the gate fabrication of AlGaN/GaN high-electron-mobility transistor.

Earthquake light, emerging from the ground as flashes at night (neglecting other more minor forms), usually has a whitehemispherical center and blue outer part. The blue resembles daytime blue sky. Its existence is increasingly verified, with about 80 videoson the web to mid-2017. However, the light must be differentiated from power-grid faults, so sound/color/form/length criteria weredeveloped in this paper through examination of many videos. Light should be coseismic (i.e. when the S-waves arrive), hemispherical,not during a storm, less than 1 s long, without fire or smoke, and without many rapid color changes. Warnings about camera artifactsare included. This light accompanied two recent earthquakes: M7.8 November 14, 2016, New Zealand, and M8.1 September 8, 2017,Mexico. Definite green flash earthquake light has only been caught once on video and it is shown that others are sometimes electricaloverload of mercury vapor lamps, or difficulty with classifying pale turquoise flashes that are only slightly more green than blue. Threeseparate frames from videos (NZ, Turkey, and Ecuador) have views actually within the blue light. These data exemplify the Freundprinciple of positive charge production from quartz by high stress-rate, then charge separation and expulsion to the ground surface andcreation of light, but the hypotheses of quartz piezoelectricity or voltages from fracture mechanisms are not accepted.