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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.

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).

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.

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.

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.

In this paper, we propose spectroscopy system, which use Complementary metal–oxide–semiconductor (CMOS) image sensor as two dimensional detectors, for studying in undergraduate laboratory. The goal of this system is to make students understand internal structure of commercial spectrometer and characteristic of light spectrum. Light with various wavelengths propagated via variable slit, which is used to adjust width of spectrum, has been focus on reflective grating and then separated to various spectrum. After that, separated spectrum has been recorded by CMOS image sensor which consists of two dimensional array pixels. Each pixel can be determined as wavelength of light by calibrating with Mercury lamp which is standard light source that has exact spectrum value. Measuring factor i.e. sensitivity and spectral resolution have been considered. By using CMOS image sensor, student can observe distribution of real light spectrum and spectrum graph together. The results show that characteristic spectrum of Mercury lamp obtained from our system exact with standard value. By considering measuring factor of spectrometer, small slit width influence system gain high resolution but it cause system has low sensitivity. Spectrum of Mercury lamp, Hydrogen lamp, Argon lamp, led flash of smartphone, and compact fluorescent lamp have been shown and compared. Moreover, our system not only be applied for undergraduate studying, but also might be applied with other optical spectroscopy method in future.

Developing highly active photocatalyst to degrade organic pollutants is a green strategy to deal with the environmental crisis. Herein, the novel BiOBr/(001)-TiO2 (TB-x) composites were synthesized via the in-situ construction method. The crystal structure, morphological structure, energy band structure and photoelectrochemical properties of TB-x were characterized, and the results show that the 2D/2D structure has a significant improvement in photo-generated carrier separation and visible light utilization. The optimal Rhodamine B (RhB) degradation reaction rate of TB-10 is 3.4 times and 2.1 times higher than pure (001)-TiO2 under Xenon lamp and Mercury lamp (500 W), respectively. Meanwhile, the TB-10 displays an excellent cycling performance during photocatalytic reaction. Based on free radical trapping and the electron paramagnetic resonance (EPR) experiments, the pivotal active group is the superoxide radicals anions (·O2-) to degrade RhB. This study offers a conception for advancing the application of TB-x photocatalyst in environmental protection.

In the manuscript, we developed a novel strategy to effectively improve the visible light absorption of Ti-based MOF by extending the conjugated degree of organic ligands in Ti-based MOFs. The freebased 5,10,15,20-tetraphenylporphyrin (H2TCPP) as organic linkers was used to facilely synthesize Ti-based MOFs (Ti-TiTCPP MOFs). The structural, morphologic and optical properties of Ti-TiTCPP MOFs were investigated. Ti-TiTCPP MOFs was applied to photocatalytic degradation of rhodamine B(RhB) and the photocatalytic degradation performances of Ti-TiTCPP MOFs were compared with that of NH2-MIL-125(Ti) MOFs under mercury lamp, xenon lamp and daylight lamp irradiation, respectively. The results showed the photocatalytic degradation performances of Ti-TiTCPP MOFs are superior to that of NH2-MIL-125(Ti) MOFs in visible region. Furthermore, the photocatalytic degradation mechanism of Ti-TiTCPP MOFs was investigated in detail based on the electrochemical and photoelectrochemical results associated with previously reported photocatalytic degradation mechanisms of NH2-MIL-125(Ti). The possible electrochemical and photoelectrochemical reactions and the changes of Gibbs free energy were analyzed. The degradation possible pathways of RhB and the emerging main intermediate contaminants were carefully analyzed by HPLC-HRMS under the present different solution parameters. And then the photocatalytic system based on Ti-TiTCPP MOFs was successfully applied to deal with real industrial textile wastewaters.

UV LED technology has revolutionized the photocatalytic processes due to their significant advantages over traditional mercury-based illumination sources, specifically its higher energy efficiency. However, the use of LED also introduces important changes in the light distribution achieved inside a photocatalytic reactor that has to be considered. In this study an exhaustive comparison of three different UV-A sources (a mercury fluorescent lamp, a 8-LED based system and a 40-LED based system) with different light distribution has been carried out. Theoretical distribution of the light was modeled in Ansys Fluent v14.5. The results of photocatalytic activity for methanol oxidation show that a homogeneous light distribution allows achieving a higher photonic efficiency. The diffuse and uniform emission of the fluorescent mercury lamp partially compensates its lower energy efficiency, leading to similar results than the 8-LED system. This fact can be explained taking in consideration that electron-hole recombination is enhanced in the areas with higher radiation intensities, decreasing the overall efficiency. In the case of the 40 LED due to the improvement of the light homogeneity and energy efficiency, higher reaction rates per kWh were achieved. These results show that despite the advantages of LED, if light distribution is not optimized it can result in lighting systems less effective than traditional ones. On the opposite, for bacterial inactivation the results show that there is no clear difference when using different lighting sources. The existence of a highly non-uniform radiation field with regions of the reactor with very high intensities seems to enhance the efficiency of the direct bacterial inactivation when LED are used, compensating the decrease in the charge transfer efficiency of the semiconductor based photocatalytic process.

Light source is a crucial factor in the application of a photochemical process, which determines the energy efficiency. The performances of acetylacetone (AA) in conversion of aqueous contaminants under irradiation with a low-pressure mercury lamp, a medium-pressure mercury lamp, a xenon lamp, and natural sunlight were investigated and compared with those of H2O2 as reference. In all cases, AA was superior to H2O2 in the degradation of Acid Orange 7. Using combinations of the different light sources with various cut-off and band-pass filters, the spectra responses of the absorbed photons in the UV/AA and UV/H2O2 processes were determined for two colored and two colorless compounds. The photonic efficiency (φ) of the two photochemical processes was found to be target-dependent. A calculation approach for the inner filter effect was developed by taking the obtained φ into account, which provides a more accurate indication of the reaction mechanisms.

Algae (Chlorella, Microcystis, Oocystis and Scenedesmus) degradation by ultraviolet radiation has been investigated. The radiation source was a low pressure mercury vapor lamp which emits monochromatic radiation at 254 nm. Experiments include initial algae concentration variation. After a period of exposure to UV radiation, algal mass concentration was reduced by more than 80%. The results were interpreted under Line Source Spherical Emission model, so quantum yield was the appropriate target variable for explaining the process. Global quantum yields are determined for Chlorella, Microcystis, Oocystis and Scenedesmus being 7.75 × 104, 3.65 × 105, 2.28 × 105, 1.74 × 104 μg E−1, respectively.

For photocatalytic degradation of organic pharmaceutical pollutants in wastewater, an important limitation is low photonic efficiency. To solve this problem, using periodic illumination is a good option. However, due to the nature of widely applied traditional mercury lamp, which cannot be turned on and off efficiently, the study of periodic illumination was limited. In this research, ultraviolet-A/light emitting diode (UVA/LED) lamp was introduced and a TiO 2 /UVA/LED photocatalytic system was setup for acetaminophen (Ace) degradation study. The background study was conducted, which included the effects of H 2 O 2 , humic acid and bicarbonate ion concentrations. Different periodic pulse frequencies were applied, results in this study shows that smallest duty cycle (0.2) and shortest cycle time (20 ms) gave the highest photonic efficiency for photocatalytic degradation of Ace in the studied range. The effect of additional H 2 O 2 was also studied. H 2 O 2 added into the heterogeneous reaction system enhanced both decomposition rate and photonic efficiency under both continuous illumination mode and periodic illumination mode. The enhancement effect of H 2 O 2 , however, was found more obvious for controlled periodic illumination, especially for small duty cycles and short cycle times. In addition, by the addition of H 2 O 2 , the mineralization of Ace was accelerated probably due to the increase of hydroxyl radical concentration.

Ultraviolet (UV) disinfection efficiency by low-pressure (LP) mercury lamp depends on the UV fluence (dose): the product of incident irradiance (fluence rate) and exposure time, with correction factors. Time–dose reciprocity may not always apply, as higher UV–LP inactivation of E. coli was obtained at a higher irradiance over shorter exposure time, for the same UV fluence. Disinfection by UV LEDs is limited by low radiant flux compared to mercury LP lamps. Our goal was to determine the UV-LED time–dose reciprocity of E. coli for four different central LED wavelengths (265, 275, 285 and 295 nm) under different fluence rates. Inactivation kinetics determined at UV-LED265 was not affected by the fluence rate or exposure time for a given UV fluence. In contrast, UV-LED275, UV-LED285, and UV-LED295 led to higher inactivation at low fluence rate coupled to high exposure time, for the same UV fluence. The intracellular damage mechanisms for each LED central wavelength were determined by using the bioreporters RecA as an indicator of bacterial DNA damage and SoxS as an indicator of oxidative stress. For 265 nm, higher DNA damage was observed, whereas for 285 and 295 nm, higher oxidative stress (possibly due to reactive oxygen species [ROS] damage) was observed. ROS inactivation of E. coli was predicted to be more effective when keeping the ROS concentration low but allowing longer exposure, for a given UV fluence.

With increasing environmental concerns, total ammonia nitrogen (TAN) removal from water ecosystems has gained much attention. Photoelectrochemical process is considered to be an environmental-friendly technology for water purification. Meanwhile, ultraviolet light-emitting diodes (UV-LEDs) and microplasma UV radiating technologies, as promising alternatives to mercury lamp, create new pathways for the development of UV-based photoelectrochemical process. In this study, the degradation of TAN from chloride-containing solutions by direct photolysis, an electrochemical process, and particularly a photoelectrochemical process were investigated to explicate the benefits of UV radiation. A synergistic effect on TAN degradation was observed in the photoelectrochemical process with the three different UV sources. The photoelectrochemical process resulted in the acceleration of TAN removal, reduction of nitrate formation, and enhancement of current efficiencies which occurred due to the generation of active chlorine radicals by UV radiation. The effects of operating conditions (chloride concentration, initial pH, and UV irradiances) were further explored. The TAN degradation rates improved by 4.9%, 16.5%, and 18.2% in the photoelectrochemical process at corresponding chloride concentrations compared with those of the electrochemical process. The TAN degradation rates were clearly enhanced by UV radiation regardless of the initial pH values. The better synergistic degradation of TAN tended to occur under acidic conditions. The TAN degradation rate was 0.319 mg L−1 min−1 in the electrochemical process and increased to 0.366 and 0.382 mg L−1 min−1 at the irradiances of 3.06 and 6.11 mW cm−2 in the photoelectrochemical process, respectively. Although the outputs of UV-LEDs and microplasma UV lamp were comparably low, there was still a synergistic effect on the degradation of TAN. However, the pH followed a distinct tendency compared with that of the photoelectrochemical process using mercury lamp. The results demonstrate the photoelectrochemical process based on emerging UV sources could be a feasible technology for the treatment of ammonia-containing wastewaters.

An efficient, oxidant and photocatalyst-free approach for the synthesis of polycyclic-fused isoindolinone derivatives is reported via annulation of 3,4-diphenyl-3-pyrrolin-2-ones along with release of the hydrogen gas under an argon atmosphere in EtOH by irradiation with a 500 W mercury lamp at room temperature. The described approach is atom-economic and environmentally friendly and tolerates various electron-donating and electron-withdrawing groups. In addition, selected annulation products, dibenzo[e,g]isoindole-1-ones, were successfully oxidized into dibenzo[e,g]isoindole-1,3(2H)- diones in DMSO in the presence of CH3ONa at room temperature.

A solar spectrometer is designed and developed, which uses a leadscrew and bar mechanism as the wavelength scanning mechanism, to achieve the accurate measurement of the solar spectrum in 170 nm–350 nm range. When measuring the standard spectrum of mercury lamp under laboratory conditions, there is a spectral drift due to temperature-induced deformation of the wavelength scanning mechanism. By using the finite element analysis method, the temperature sensitivity of each component in mechanism is analyzed. And then the linear superposition relationship between temperature rise and deformation is determined. Combined with the working principle of wavelength scanning mechanism, the corresponding relationship between temperature change and spectral drift is deduced. Spectral scanning and temperature monitoring were carried out simultaneously in instrument test to acquire temperature data of the wavelength scanning mechanism as it driving the gratings. Spectral drift was estimated according to the temperature variation and the maximum deviation between the predicted wavelength drift and the measured wavelength drift is 0.0016 nm, which is 6% of the measured wavelength. The experiment data validate the theoretical analysis results. The relationship between temperature change and spectral drift provides a theoretical reference for the correction of the measurement results and the thermal control of the instrument.

2-Propoxy-1-naphthamide possessing a chiral 2-methylpyrrolidine group exists as a mixture of four diastereomers owing to the rotation of the Ar (C O) and C( O) N bonds. The diastereomers existed in the ratio of 32:32:14:22 in CD3OD. When the MeOH solution of the mixture of diastereomers was irradiated with Pyrex filtered UV light (>290 nm) from a high-pressure mercury lamp, the ratio changed to 27:4:43:26. The diastereomeric ratio was reversibly controlled by irradiation and heat. The change was accurately reflected in the intensity of the CD spectra. Furthermore, the reversible axial chirality was transferred to the optical activity of asymmetric reaction products via the photochemical cycloaddition reaction with 9-cyanoanthracene.

The photocatalytic degradation of Xylene Milling Yellow 6 G in aqueous solutions under UV exposure was studied with sol–gel synthesized CeO 2 catalyst. The effects of catalyst loading, initial dye concentration, pH and temperature were studied and the optimum values for maximum degradation were determined. Using a 125 W high pressure mercury lamp, an optimum degradation of 10 ppm dye solution was observed with 1 g/L catalyst. Initial dye concentration exhibited a significant negative effect on photocatalytic degradation. With 1 g/L catalyst, natural pH of the solution, ambient temperature, and initial dye concentration of 10 ppm, complete degradation was achieved within 30 min of UV exposure. The sol–gel synthesized catalyst showed better photocatalytic activity than combustion synthesized as well as commercial catalysts. A degradation mechanism was proposed based on the degradation products identified by LC–MS.

A consequence of the massive use of pesticides in fruit harvesting is that many fruit juices contain pesticide traces that can be hazardous to the health of consumers. The wastewater generated in the fruit process after cleaning the fruit also contains pesticides in concentrations that cannot be dumped into the environment so these substances have to be previously eliminated. As thermal and the biological treatments do not degrade most pesticides used, an alternative treatment has to be applied to eliminate these toxic compounds both in fruit juices and wastewater. In the present work, a photochemical treatment with UV radiation was applied to eliminate thiabendazole from aqueous solutions at different pH and temperatures, using a medium-pressure mercury lamp that emitted in the range of wavelengths between 255 and 750 nm. The absorbed radiation was calculated as a function of the concentration of thiabendazole. A reaction mechanism was proposed, so combining it with the mathematical relation found between the absorbed radiation and thiabendazole concentration suggests a pseudo-first-order kinetic model that, for the range of concentrations studied, can be simplified to a zero-order kinetic model, both of which fit the experimental data obtained well.

Excilamps are mercury-free gas-discharge sources of non-coherent VUV or UV radiation with high radiant power and a long lifetime. The most efficient excilamp that is currently available on the market is a VUV xenon excilamp system (Xe2(*)-excimer lamp, λ(max) = 172 nm) with a stated radiant efficiency η of 40% at an electrical input power P(el) of 20 W, 50 W or 100 W. In this paper, the use of this highly efficient Xe2(*)-excilamp (P(el) = 20 W) for water treatment is demonstrated using a recirculating laboratory photoreactor system with negative radiation geometry. The efficiency in the 172 nm initiated bleaching of aqueous solutions of Rhodamine B is compared to that initiated by a common low-pressure mercury (LP-Hg) lamp (185 nm, TNN 15/32). The dependence of the pseudo zero order rate constant k´ of decolorization of RhB on the flow rate and on the initial concentration of RhB was investigated. Both lamps exhibited dependences of k´ on the initial concentration of RhB, which represents a typical saturation kinetical behavior. The saturation kinetics was very prominent in the case of the Xe2(*)-excilamp. Also, the Xe2(*)-excilamp treatment exhibited a significant influence on the flow rate of the RhB aqueous solution, which was not the case during the LP-Hg lamp initiated bleaching of RhB. The results of this paper demonstrate that Xe2(*)-excilamps can be used for VUV-initiated water purification. However, to reach the maximum efficacy of the Xe2(*)-excilamp for photo-initiated water purification further engineering optimization of the photoreactor concept is necessary.

This work presents novel photochemical reactors with integrated titania photocatalyst for the UV photodecomposition of gaseous methyl iodide present in simulated vessel off-gas (VOG) in a nuclear fuel reprocessing facility. Continuous flow reactors composed of fluorinated ethylene propylene (FEP) were designed and constructed to allow transmission of UV light into the reactor while also providing resistance to the corrosive nature of methyl iodide. Titania nanotube photocatalyst increases methyl iodide photolysis rate by two orders of magnitude compared to that with UV light alone. The rate constant for methyl iodide photolysis with and without catalyst directly depends on the intensity of the light at the location of the reaction, which is inversely proportional to the distance from the linear light source. The titania photocatalyst is significantly active at low light intensity where no detectable reaction occurs in absence of catalyst. For example, at an initial concentration of 400 ppb methyl iodide, a residence time of 9 s, and a light intensity of 0.5 mW/cm2, conversions with and without titania photocatalyst are >99% and 0%, respectively. The UV light source is a low-pressure mercury vapor lamp with primary emission at 254 nm, the wavelength that is in the range of highest cross-sectional absorbance for methyl iodide. Parameters investigated in this work include UV lamp to reactor distance (light intensity), impact of humidity, gas phase composition, and catalyst form (nanotube vs powder). This work also demonstrates that titania possesses a characteristic activation period on the order of approximately one hour to reach its full steady-state activity.

Highly (100) oriented Y2Hf2O7 thin films were grown on YSZ substrates by magnetron sputtering. The band-gap of 5.1 eV for the Y2Hf2O7 thin film was evaluated by optical transmission spectroscopy. UV photodetectors based on the Y2Hf2O7 thin films were fabricated. Excellent photoelectric responses were observed in dark and under illumination by low-pressure mercury lamp, such as photo-current to dark-current ratio of 120, photo-responsivity of 139 A/W, and the detectivity of 3.8 × 1013 Jones. The device showed fast response with the rise time of 0.04 s and the decay time of 0.1s.

A comparative study was performed to assess the efficacy of UV-C light emitting diodes (UV–C LEDs) at 277 nm and a low-pressure mercury (LPM) lamp at 253.7 nm to inactivate Penicillium expansum spores on apple skin at 4 °C or 25 °C. In saline solution, the D value for the inactivation of spores using 277 nm at 25 °C was 6.62 mJ cm−2 and 7.19 mJ cm−2 at 4 °C, both of which were significantly lower than the D value at 253.7 nm (9.26 mJ cm−2). The UV-mediated inactivation of spores on the surface of apple skin followed non-linear kinetics with an initial linear phase followed by tailing. The calculated D values for spores on apple surface were significantly higher compared to within saline (14.49 and 18.80 mJ cm−2 with 277 nm at 25 °C and 4 °C, respectively, compared to 23.00 mJ cm−2 with 253.7 nm). This could be due to protective effects of apple peel constituents or the non-uniform energy distribution due to the uneven apple surface. Yet, the log reductions achieved (>2 log CFU) were equivalent to washing in hypochlorite solution (200 mg L−1 free-chlorine) which is the current industrial practice. UV-C light at 277 and 253.7 nm (500 mJ cm−2) was shown to prevent growth of blue mould and subsequent spoilage of inoculated and stored apples (28 days) if treated prior to damage. The UV-C treatments at doses corresponding to reduction of 2 log CFU of P. expansum did not impact apple physico-chemical quality parameters during 12 weeks of storage at 25 °C.

The surface of the hair is the region most exposed to solar radiation and to the environment in general. Many of the well-known damaging effects of sun exposure on hair must start or even be restricted to the most external cuticle layers. As such, this work investigates morphological, ultrastructural and chemical changes in the outermost cuticle layer of dark brown hair, using atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The results showed that after 230 h of irradiation with a mercury lamp, small bumps with globular shape (heights lying in the 1-5 nm range) appeared on the cuticle surface and their size increased with increasing irradiation times. In addition, the enlargement of pre-existing holes was also observed (holes increase around 350% in depth) and the height of the steps formed between the edges of two cuticle scales increased around 65%, as a result of 500 h of irradiation. The damages in hair strands were accurately identified by analyzing exactly the same surface region before and after irradiation by AFM images. Finally, the results were discussed in terms of the chemical differences between the non-irradiated and the irradiated hair, for instance, the increased level of cystine oxidation as a consequence of photodegradation.

The emission spectrum of cryogenic liquid xenon in the vacuum ultraviolet region was measured by irradiating liquid xenon with gamma-rays from a radioactive source. To achieve a high signal-to-noise ratio, we employed coincident photon counting. Additionally, the charge of the photo-sensor signals was measured to estimate the number of detected photons accurately. In addition, proper corrections were incorporated for the wavelength; response functions of the apparatus obtained using a low-pressure mercury lamp, and photon detection efficiencies of the optical system were considered. The obtained emission spectrum is found to be in the shape of a Gaussian function, with the center at 57,199±34 (stat.)±33 (syst.) cm−1 (174.8±0.1 (stat.)±0.1 (syst.) nm) and the full width at half maximum of 3328±72 (stat.)±65 (syst.) cm−1 (10.2±0.2 (stat.)±0.2 (sys.) nm). These results are the most accurate values obtained in terms of the data acquisition method and the calibration for the experimental system and provide valuable information regarding the high-precision instruments that employ a liquid-xenon scintillator.

The time-resolved spectra of the irradiation emitted from solar simulators employing the two types of high-intensity discharge arc lamps that are commonly used in solar simulators, i.e. metal halide (here 6 kW) and xenon arc (here 5 kW) lamps, are reported. The lamp emission was recorded by a fast-response photodiode, which reveals that the amplitude of oscillating irradiation intensity from the metal halide lamp is approximately 60% of the peak intensity, while its oscillation frequency is twice of the frequency of the AC power supply, here 100 Hz. The irradiation of the xenon arc lamp is powered by a modulated DC supply to oscillate at 300 Hz, with an amplitude that is found to be only approximately 9% that of the peak intensity. An intensified CCD camera, which was coupled with a spectrometer operating in a range of 350–900 nm, was synchronized with the lamp to provide phase-resolved spectra. The irradiation from the xenon arc lamp was found to be spectrally stable with time; while that from the metal halide lamp varies significantly throughout oscillation cycle, especially at the shorter-wavelengths of below 550 nm. All spectra were calibrated to reveal that the time-averaged spectrum of the simulator with a metal halide lamp matches the solar spectrum significantly better than does that from a xenon arc lamp. The reflecting surface of polished ellipsoidal reflector was found to reduce the intensity of selected frequency bands by up to 10%, while that from both the polished ellipsoidal reflector and conical concentrator was found to reduce the intensity in selected frequency bands by up to 20%.

In order to improve the efficiency and durability of semiconductor photocatalyst for degrading vehicle exhausts, a highly active degradation micro-unit was designed by crosslinking nano-TiO2 to the surface of fine crumb rubber with coupling agent. The dependence of degradation efficiency of NO2 on preparation parameters and test conditions were studied. Laboratory tests showed that the degradation rate of NO2 could reach 90% under the appropriate test environment such as initial NO2 concentration of 20 mg/m3, a mercury lamp with illumination of 1000 lx, temperature of 25 °C, relative humidity of 50% and rubber powder of 80 mesh. Tunnel tests showed that the concentration of NO2 in test section was 0.1–0.3 mg/m3 lower than those of contrast sections and the degradation rate reached 60% in 1 h. Since a three-dimensional contact area among nano-TiO2, exhausts, moisture and light was formed on the surface of rubber powders, the proposed technology is expected to provide a new way for greatly improving the degradation efficiency of vehicle exhaust by asphalt pavements.

In this research, photocatalytic decolorization and its kinetics study of auramine dye at various aqueous buffer and non-buffer media using nano-titanium dioxide in two different sizes of 15 and 70 nm in a photocatalyic reactor under 400 W high pressure mercury lamp irradiation under aerobic condition is described. The effects of some physico-chemical parameters such as photocatalyst dosage, medium pH and irradiation time were investigated in the presence of two different nano-photocatalysts and then the results were compared with each other. Kinetics study of photocatalytic treatment of auramine dye resulted that the dye decolorization approximately follows a pseudo-first order kinetic behavior according to the Langmuir–Hinshelwood model. Ultimately, the observed rate constants, experimental half-times, adsorption constants and decolorization rate constants at surface at buffer and non-buffer media under aerobic conditions were evaluated.

Whether or not pulsed UV light was more bactericidal than continuous UV was still debated. The aim of this work was to compare the disinfection efficiency of continuous and pulsed UV light at different frequencies. A tunable frequency UV system was designed to allow indicator bacteria to be exposed to continuous or pulsed UV light with a same low pressure mercury lamp, which can emit UV light with a wavelength of 253.7 nm, and the pulse frequency was adjustable. The germicidal ability against Escherichia coli and Salmonella spp. of pulsed UV light at frequencies 0 (represented continuous irradiation), 2, 4, 6, 8, 10 Hz was compared. The results showed that pulse frequency is a factor influencing the ultimate inactivation ability of pulsed UV light and at specific frequencies pulsed UV light was more bactericidal than continuous UV. Industrial relevance Pulsed UV light for microbial inactivation has been applied for more than 30 years. As a very important factor, pulse frequency has been ignored for a long time. We have demonstrated that at some specific frequencies, pulsed UV light was more bactericidal than continuous UV using low pressure mercury lamp. And if further studies could come to the similar results in inert-gas flash lamps and/or medium-pressure UV lamps and figure out the optimal pulse frequency, it might improve the sterilization efficiency of the existing pulsed UV system.

Second-harmonic generation (SHG) from a twin-hole fiber by thermal poling was studied. Quasi-phase-matching (QPM) was performed with a low-pressure mercury lamp. Erasure of the second-order nonlinearity was studied by uniform exposure, and after that QPM was performed using a photomask erasing the nonlinearity periodically. SHG was measured with a Q-switched Nd3 +:YAG laser. The second-harmonic power increased by a factor of 7 after QPM. A ray-tracing analysis on the light distribution of the lamp after the photomask was performed, and the effect on QPM is discussed. A model for the second-order nonlinearity by charge layers is also discussed.

An ultraviolet (UV) process using a low-pressure mercury lamp is affected by ambient humidity. It is due to strong influence of humidity on the production of ozone and other radicals by the UV light. In this paper, a photochemical reaction model under the irradiation of a low-pressure mercury lamp is developed, and the effect of humidity on the production of ozone and other radicals [O, O ( D 1 ) , O2(a1Δg), O 2 ( b 1 Σ g + ) , OH, HO2, H, and H2O2] by a low-pressure mercury lamp is discussed using the reaction model. The validity of the reaction model is confirmed by comparing the ozone densities calculated using the model with experimentally measured ozone densities, and they showed good agreement. The reaction model shows that the ozone density decreases with increasing humidity for three reasons: (i) attenuation of 185 nm light due to absorption by H2O, leading to a decreased O atom production by O2 + hν(185 nm) ⟶ O + O which is required to produce ozone by O + O2 + M ⟶ O3 + M; (ii) ozone destruction by O 3 + h ν ( 254 nm ) ⟶ O ( D 1 ) + O 2 ( a 1 Δ g ) , where the resulting O ( D 1 ) partly reacts with H2O before converting back to O3 after quenching to O; and (iii) an ozone destruction cycle OH + O3 ⟶ HO2 + O2 and HO2 + O3 ⟶ OH + 2O2. The effect of humidity on the densities of other radicals is also discussed using the reaction model.

This work studied the effect of multi-wavelength UV processing on the ascorbic acid content of aqueous solutions, at different pH values (3, 4, and 5). The source of radiation was a mid-pressure mercury lamp (460 W), emitting between 250 and 740 nm. The samples were treated for 60 min, at 25 °C and 45 °C, with the lamp on and with the lamp off. A radiation balance was performed to estimate the total radiation power absorbed by the whole solution. Ascorbic acid content was reduced, either in irradiated or non-irradiated solutions, due to aerobic oxidation. But, in most cases, irradiation did not accelerate degradation. This can be explained by the fact that ascorbic acid barley absorbs ultraviolet in the interval of wavelengths emitted by the lamp (only 31% of the incident radiation P(0) could be absorbed by the solutions). Therefore, mid-pressure mercury lamps are helpful to avoid Vitamin C photo-degradation.

Spruce samples (Picea abies Karst.) were irradiated by a strong ultraviolet (UV) light emitter mercury lamp, and another series of specimens were treated with the combination of UV radiation and water leaching. The total duration of UV radiation for both series of specimens was 10 days. One treatment cycle consisted of 24 h of UV irradiation, followed by 6 h of water leaching. This cycle was repeated 10 times. The chemical changes were determined by IR spectroscopy, and the difference spectrum method was used for evaluation. The IR measurement was carried out after each UV radiation as well as after water leaching, to determine the effect of UV radiation and water leaching separately. The lignin degradation was more significant for the leached samples than for the pure UV treated samples. The chemical components most sensitive to leaching were the unconjugated carbonyl groups generated by the photodegradation. As a consequence of photodegradation, two absorption bands of unconjugated carbonyl groups emerged at 1714 and 1750 cm−1 wavenumbers. The band at 1750 cm−1 was much more sensitive to leaching by water than the band at 1714 cm−1. This band almost disappeared after eight cycles. The water was able to leach out carbonyl groups (absorbing at 1741 cm−1) that had been present in the wood originally as well.

A photochemical reactor composed of an Hg-MDEL was applied in photodegradation studies of fluoxetine (Prozac®). The reactor exhibited to be an efficient hydroxyl radical generation system, since the O • H quantification studies conducted with coumarin (COU), 4-hydroxycoumarin (4HC) and 7-hydroxycoumarin (7HC) solutions resulted in the kinetics constant of formation of O • H kOH = 3.14 ± 0.18 min−1. When the Hg-MDEL reactor was applied for degradation of Prozac®, the study of variation of the microwave power allowed a significant increase in the rate of degradation of the Prozac®, indicating that the hydroxyl radical formation is optimized through the adjustment of this parameter. An increase in the initial concentration of Prozac from 33 to 134 μmol L−1 resulted in a 21% decrease in the kinetic constant value, the mean kinetic constant was k = 10.64 ± 1.25 min −1 and R 2 = 0.943 ± 0.131. The Prozac® photodegradation studies showed that the application of the pseudo-first-order kinetics should be limited to the time of up to 0.50 min for the respective system, due to the influence exerted by the transformation products. In general, the total removal of Prozac® was 100% for its highest concentration (134 μmol L−1) at the time of 0.75 min. As for the solution of Prozac® 101 μmol L−1, the energy consumption was 6 kW h g−1, achieving a removal of 99%. Finally, the photochemical system presented in this work demonstrates a high efficiency in the formation of hydroxyl radicals, a high degradation rate of organic compounds (Prozac®, COU and 7HC) and low energy consumption.

The kinetics of Tartrazine decay through photo-Fenton process, which has not reported in literature, was explored. Tartrazine is a synthetic azo dye used in food colorants industry, cosmetic and textile industry. There are very few studies in the literature concerning Tartrazine degradation but they did not lead to a total mineralization. Fotooxidative degradation of Tartrazine (E102) by UV/Fe2+/H2O2 was investigated using a laboratory scale photoreactor equipped with a low pressure mercury lamp. The degradation kinetics under irradiation (200–280 nm) was optimized in respect to H2O2 concentration (6 × 10−4 M) and Fe2+ concentration (8.28 × 10−5 M) at a constant Tartrazine concentration (1.035 × 10−5 M) at pH 3. The degradation rate was influenced by the temperature with an optimum value of 323 K and thermodynamic parameters were calculated. Application of photo-Fenton system also assures total organic carbon removal with 80% efficiency after 2 h irradiation.

Bromate is a potential carcinogen that forms during the treatment of bromide-containing water using ozone-based technologies. A study of humic acid (HA) removal and bromate formation in UV/O3 and ozone processes was conducted relative to a variety of operational conditions, such as ozone dosage, pH and initial concentrations of HA and Br−. Additionally, UV irradiation with the addition of ozone, which was generated by the same low-pressure mercury lamp (emitting 254 nm and 185 nm), was studied. Bromate concentrations during the UV/O3 process were 17.1–77.6 μg/L, which was 2.1–2.9 times the concentration for the O3 process, when ozone at concentrations ranging from 1.5 to 6.3 mg/L was continuously applied to water to which no HA was added. UV radiation reduced the concentration of the residual ozone, which was important for the formation of bromate. HA inhibited bromate formation, which was especially dramatic in UV/O3 process, and increasing the initial concentration of Br− accelerated the bromate formation in both processes; however, enhancement of bromate formation after increasing the pH was only observed for O3 process. Reducing the ozone dosage in UV/O3 process lessened both residual ozone concentration and hydroxyl radical ( OH) exposure; changing this parameter led to a slight drop in the rate of HA removal but also caused a significant decrease in the bromate formation. Therefore, the combination of UV irradiation and low doses of ozone represented a promising method for the simultaneous control of bromate formation and HA removal. Because the UV lamp can also generate a low concentration of ozone, combining UV irradiation with the internally generated ozone is recommended.

Polymethyl substituted [2.2]metaparacyclophanes were synthesized via the corresponding 2,11-dithia [3.3]metaparacyclophanes. Photooxygenation reaction of 4,5,6,12,13,15,16-heptamethyl[2.2]metaparacyclophane using a high pressure mercury lamp led to the mono-endoperoxidation of only the para benzene ring; this was attributed to the much larger degree of deformation of the para-benzene ring than of the meta-benzene ring. On the other hand, whilst irradiation of the photoreaction of 4,5,6,8,12,13,15,16-octamethyl[2.2]metaparacyclophane under the same reaction conditions produced only the bis-endoperoxide (on both the meta- and para-benzene rings).

International audience; An intramolecular [2 + 2] photocycloaddition is performed in a microphotoreactor (0.81 mL) built by winding FEP tubing around a commercially available Pyrex immersion well in which a medium pressure mercury lamp is inserted. A rigorous comparison with a batch photoreactor (225 mL) is proposed by means of a simple model coupling the reaction kinetics with the mass, momentum and radiative transfer equations. This serves as a basis to explain why the chemical conversion and the irradiation time are respectively increased and reduced in the microphotoreactor relative to those in the batch photoreactor. Through this simple model reaction, some criteria for transposing photochemical synthesis from a batch photoreactor to a continuous microphotoreactor are defined.

Eu3+ and Ho3+ doped Sr2TiO4 were synthesized by using solid-state reactions. Samples sintered at 1300 °C for 6 h could be indexed to Sr2TiO4 with a single phase. Eu3+ in Sr2TiO4 emitted orange light under the excitation at 365 nm in a broad band which was coupled well with the strongest emission of high pressure mercury vapor lamps. Ho3+ in Sr2TiO4 emitted yellow light under blue excitation from 450 to 460 nm which agreed well with the emission of blue InGaN-based light-emitting diodes. The present results indicated that Sr2TiO4 was a promising host for high pressure mercury vapor lamps or white light-emitting diodes.

The modifications of properties of some semi-interpenetrating polymer networks based on aromatic polyurethane and a crosslinked epoxy resin, during UV irradiation with a mercury lamp ( λ > 300 nm), were investigated. Variation of some properties, such as colour, gloss, contact angle, mass variations and water retention were monitored according to the irradiation time. Photochemical reactions that occurred during irradiation were monitored by FT-IR. The results demonstrated that polyurethane-epoxy resin semi-interpenetrating polymer structures showed a higher photo-stability than the polyurethane sample.

This study presents a highly sensitive, all-fiber sensor for in situ detecting light. A fiber-optic light sensing platform was created by overlaying an in-line side-polished fiber (SPF) with a photoresponsive liquid crystal (P-LC) consisting of an azobenzene dye, a chiral dopant, and a nematic LC. The resulting P-LC overlaid SPF light sensor is sensitive to three different light sources, including 380 nm light emitting diode (LED), mercury lamp, and office ceiling lights. Under the light illumination, the energy of irradiation from short wavelengths of light (

A research study has been performed to determine the ultraviolet (UV) fluence-response of several target non-pathogenic microorganisms to UV light emitting diodes (UV-LEDs) by performing collimated beam tests. UV-LEDs do not contain toxic mercury, offer design flexibility due to their small size, and have a longer operational life than mercury lamps. Comsol Multiphysics was utilized to create an optimal UV-LED collimated beam design based on number and spacing of UV-LEDs and distance of the sample from the light source while minimizing the overall cost. The optimized UV-LED collimated beam apparatus and a low-pressure mercury lamp collimated beam apparatus were used to determine the UV fluence-response of three surrogate microorganisms (Escherichia coli, MS-2, T7) to 255 nm UV-LEDs, 275 nm UV-LEDs, and 254 nm low-pressure mercury lamps. Irradiation by low-pressure mercury lamps produced greater E. coli and MS-2 inactivation than 255 nm and 275 nm UV-LEDs and similar T7 inactivation to irradiation by 275 nm UV-LEDs. The 275 nm UV-LEDs produced more efficient T7 and E. coli inactivation than 255 nm UV-LEDs while both 255 nm and 275 nm UV-LEDs produced comparable microbial inactivation for MS-2. Differences may have been caused by a departure from the time-dose reciprocity law due to microbial repair mechanisms.

The luminescent properties of microwave discharge electrodeless mercury lamp (MDEL-Hg) which was ignited within the resonant cavity and photolysis of hydrogen sulfide with low concentration were studied in this paper. Experiment results indicated that the Interior MDEL-Hg could be made the best of energy utilization and the efficiency of photolysis of H 2 S was very significant under the experimental conditions with the initial H 2 S concentration of 7.9 mg m −3 . With residence time of 1.5 s, the removal efficiency of hydrogen sulfide was 91%, the absolute removal amount (ARA) was 3.24 μg s −1 and the energy consumption was 58.23 mg (kW h) −1 .

This paper proposes the use of photochemical vapor generation with acetic acid as sample introduction for the direct determination of ultra-trace mercury in white vinegars by atomic fluorescence spectrometry. Under ultraviolet irradiation, the sample matrix (acetic acid) can reduce mercury ion to atomic mercury Hg 0 , which is swept by argon gas into an atomic fluorescence spectrometer for subsequent analytical measurements. The effects of several factors such as the concentration of acetic acid, irradiation time, the flow rate of the carrier gas and matrix effects were discussed and optimized to give detection limits of 0.08 ng mL − 1 for mercury. Using the experimental conditions established during the optimization (3% v/v acetic acid, 30 s irradiation time and 20 W mercury lamp), the precision levels, expressed as relative standard deviation, were 4.6% (one day) and 7.8% (inter-day) for mercury ( n = 9). Addition/recovery tests for evaluation of the accuracy were in the range of 92–98% for mercury. The method was also validated by analysis of vinegar samples without detectable amount of Hg spiked with aqueous standard reference materials (GBW(E) 080392 and GBW(E) 080393). The results were also compared with those obtained by acid digestion procedure and determination of mercury by ICP-MS. There was no significant difference between the results obtained by the two methods based on a t -test (at 95% confidence level).

Optical transmission of PMMA (polymethylmethacrylate) POF (polymer optical fibre) in the spectral range from 280 to 450 nm is investigated with a high radiation emission source comprising a mercury lamp delivering 40 W/cm 2 at the PMMA POF launch face. The heat generated from the radiation source causes a sudden drop in the launched radiation due to thermal-oxidation and photo-degradation of the launch face of the PMMA POF; this results in a loss of 53% of the total launched power within 13 min of exposure to the source. The thermal-oxidation degradation is controlled by a cooling device which improves the transmission stability of the fibre. However, photo-degradation is still active and causes a loss in power of 7% in 13 min. The spectral output of the transmitted radiation through the PMMA POF was monitored and indicates the variation in optical loss with wavelength. High rates of nominal absorption for the irradiated PMMA POF are found below 320 nm wavelength. From the Beer–Lambert law, the photo-degradation effect with time of a fixed path length of PMMA POF is described by the absorption coefficient ( α λ , cm −1 ) . The nominal absorption coefficient α λ values in the range 335–368 nm wavelength are found to be higher after 1 h of irradiation than the values in the range 406–438 nm. However, the relative change in the nominal absorption coefficient Δ α λ is greater at 438 nm than at 335 nm, 368 or 406 nm. After 1 h of irradiation with the cooling device in place, the PMMA POF transmission was reduced to 44.8% of its initial value; this recovered to a maximum of 86% of the original transmission of the total launched power after 5 weeks in ambient conditions.

A new production method of long-period fiber-gratings using neither a laser nor a fine-positioning system was proposed. A low-pressure mercury lamp emitting 254 nm ultraviolet light was used as a light source. Hydrogen-loaded Ge–B co-doped fiber was exposed to the emission of the lamp through an amplitude mask. A coupling loss up to 23 dB was obtained for a grating period of 212 μm. The maximum coupling loss for a grating period of 460 μm was 18 dB. The growth rate of the refractive index change by mercury-lamp exposure was 1.3 × 10−4/h. The temperature and strain characteristics were measured and compared with those fabricated by excimer-laser exposure. The temperature and strain sensitivities of long-period gratings with a period of 212 μm were higher than those of 460 μm. The temperature and strain sensitivities of those by mercury-lamp exposure were almost equal to those by excimer-laser exposure of the same fiber. The sensitivities of those by excimer-laser exposure of non-loaded fiber were higher than those of hydrogen-loaded fiber by mercury-lamp or excimer-laser exposures except for the temperature sensitivity of a grating period of 460 μm.

A porous glass tube with a composition of 96SiO 2 ·4B 2 O 3 (wt%) supported TiO 2 shows high photooxidation activity due to its transparency and large surface area. The surface area of the porous glass tube supported TiO 2 is 10,000 times larger than that of conventional materials. TiO 2 crystals supported are anatase type. Transparency of the porous glass tube is very important. Herein, sol–gel and chemical vapor deposition (CVD) processes were employed as TiO 2 supporting processes. CVD process is more effective. For instance, an aqueous methylene blue solution with 1 ppm concentration almost thoroughly decomposes at a contact time of 300 s using porous glass tube supported TiO 2 prepared by CVD process under irradiating with 10 W low-pressure mercury lamp, on the other hand, opaque porous alumina tube supported TiO 2 was only 25%. The smaller the pore size of the porous glass tube, the larger the transparency and the permeation resistance through porous glass tube. Hence, porous glass tube with ca. 40 nm pore diameter is suitable from the standpoint of a practical use.

Photo-solid-phase microextraction (photo-SPME) has been employed to study the photolysis of three common indoor air pollutants: coumarin, butylated hydroxytoluene, 2,6-diisopropylnaphthalene. Analytes were first extracted by SPME, and the fibre was subsequently exposed to an irradiation source (i.e. xenon arc or low-pressure mercury lamp) for the selected time (from 2 to 120 min). Analyses of the irradiated fibres were carried out by gas chromatography-mass spectrometry (GC-MS) detection. Photodecay kinetics exhibited a first-order behaviour and their rate constants and half-life times were estimated. Twenty-five photoproducts have been tentatively identified by means of their mass spectra. On the basis of the identified transformation compounds, some photodegradation pathways were proposed. The photoformation-photodecay kinetics of the identified by-products were also monitored by photo-SPME. To the best of our knowledge, photolytic routes for coumarin, butylated hydroxytoluene and 2,6-diisopropylnaphthalene have not been previously investigated.

Ultraviolet germicidal irradiation (UVGI) uses UVC radiation produced by low pressure mercury vapor lamps to control biological air contaminants. Ambient air velocity and temperature have a strong effect on lamp output by influencing the lamp surface cold spot temperature. In-duct UVGI systems are particularly susceptible to ambient effects due to the range of velocity and temperature conditions they may experience. An analytical model of the effect of ambient conditions on lamp surface temperature was developed for three common lamp types in cross flow from a convective–radiative energy balance assuming constant surface temperature. For one lamp type, a single tube standard output lamp, UVC output and cold spot temperature data were obtained under typical in-duct operating conditions. Over an ambient temperature range of 10–32.2 °C and an air velocity range of 0–3.25 m/s, measured cold spot temperature varied from 12.7 to 41.9 °C and measured lamp output varied by 68% of maximum. Surface temperatures predicted by the heat transfer model were 6–17 °C higher than corresponding measured cold spot temperatures, but were found to correlate well with cold spot temperature via a two-variable linear regression. When corrected using this relationship, the simple model predicted the cold spot temperature within 1 °C and lamp UVC output within ±5%. To illustrate its practical use, the calibrated lamp model was employed in a simulation of the control of a contaminant in a single-zone ventilation system by an in-duct UVGI device. In this example, failure to account for the impact of ambient condition effects resulted in under-prediction of average space concentration by approximately 20% relative to a constant output system operating at maximum UVC output.

A portable minianalyzer was built for mercury determination in air which is based on cold vapor atomic absorption spectrometry (CVAAS) at 184.9 nm mercury line. The new instrument was made of the following principal units: a low pressure mercury lamp, a flow cell, a radiation detector (a special photomultiplier tube, sensitive only to radiations of λ < 200 nm), an electronic amplifying and displaying system and a line for analyzed air and mercury vapor standards circulating through the minianalyzer. The developed mercury minianalyzer is a non-dispersive instrument (without monochromator, lens or other optical components). The mercury vapors in air could be determined between 0.25 and 20 μg Hg/m3. Its sensitivity for mercury vapor determination at 184.9 nm line was 2.54 times higher in comparison to measurements done at 253.7 nm line with a commercially available instrument. It's cheaper, simpler and more sensitive than the commercially available mercury vapors minianalyzers.