Black Lamp Research Articles

Comparative evaluation and influence of various staining agents on color stability and fluorescence of different esthetic orthodontic wires: An in vitro study.

This study aimed to compare and evaluate the effect of three staining solutions on the color stability of three different brands of esthetic archwires using a spectrophotometer and also to compare the fluorescence of esthetic archwires with extracted human teeth. A total of 84 nickel-titanium (NiTi)-coated esthetic archwires with the same cross section and size (0.016 × 0.022″) were included. All samples were divided into four groups of 21 each, that is, group 1: artificial saliva (AS), group 2: coffee (C) solution, group 3: turmeric (T) solution, and group 4: chlorhexidine (CH) mouth rinse; each group was subdivided into three subgroups of seven each (Opal Classic (OC), Libral Rabbit Force (LRF), and Ortho Organizers (OO)). The baseline value (T0) was measured before immersion in the staining solution and then immersed in the staining solution for 21 days. The color measurements were recorded at different time intervals on the 7th, 14th, and 21st days using a spectrophotometer. The fluorescence of archwires is tested in a dark atmosphere using a fluorescent black lamp. The data obtained were analyzed using descriptive statistics, analysis of variance (ANOVA), and post hoc Bonferroni test. A significant amount of color change in all three brands of archwires from day 0 to day 21 (p < 0.005) was observed, except for OC in the CH mouth rinse group (p = 0.230). The fluorescence of OO matches with the natural teeth. LRF showed the highest overall color change followed by OO and OC. Turmeric is the most chromogenic agent, followed by Coffee and CH mouth rinse.

Comparison of Photosynthetic Characteristics and Reproductive Traits of Winter Squash (&amp;lt;i&amp;gt;Cucurbita maxima &amp;lt;/i&amp;gt;L.) Between Cultivars

The production of winter squash used vertical trellising was popular in the greenhouse for easy to manage growth and fruiting. This study investigated the photosynthetic characteristics of six winter squash cultivars to explore the differences in crop production efficiency between cultivars by vertical trellising cultivation. Plant growth, photosynthetic characteristics and fruit quality of winter squash cultivars ‘Black lamp’, ‘Tastemaker’, ‘East elite’, ‘Julius’, ‘Sugar’ and ‘Lyric’ were surveyed. The photosynthetic rate (Pn) was measured on the 70^th day after planting. We selected the three leaves above the fruit in which to compare the Pn between cultivars, and surveyed all leaves on ‘Black lamp’ and ‘East elite’ in order to make a comparison between nodes. The Pn values of ‘Black lamp’, ‘East elite’, ‘Lyric’ and ‘Tastemaker’ were significantly higher, at 14.02, 13.06, 12.33 and 12.19 μmol CO₂/m²∙s, respectively. The Pn of the leaves on 5–8^th nodes decreased significantly, and the Pn of the 1^st–5^th nodes up to the fruit also decreased. With regards to reproductive traits, the first pistillate flowers of ‘East elite’ and ‘Black lamp’ bloomed on the 30^th day after planting, while the other cultivars bloomed on the 35–37^th day after planting. The six cultivars were classified according to the size of the fruit on the 48^th day after pollination: ‘Lyric’ and ‘Tastemaker’ were classified into the largest group, at 1203 and 1106 cm³, respectively; the second group contained ‘East elite’ and ‘Julius’, at 870 and 687 cm³; while ‘Sugar’ and ‘Black lamp’ were in the smallest group, at 353 and 217 cm³, respectively. The soluble sugar and total soluble solid (TSS) contents of ‘East elite’ were significantly elevated, their values being 630.6 g/kg and 13.3%, respectively. The starch content of ‘Lyric’ was the highest at 193.7 g/kg. "Black Light" was a fruit-number type, and the increase in fruit number could increase the yield/plant; "East elite" was a fruit-weight type, and the yield per plant was related to the weight of a single fruit. The influence of the unit leaf of “Black Lamp” on the fruit fresh weight was the lowest performance in the reproductive growth. In order to increase productivity of small fruit such as ‘Black lamp’ western pumpkin, the balance between the vegetative growth and the reproductive growth was necessary to be improved.

TiO2-PDMS Super Hydrophilic Coating with Self-Cleaning and Antimicrobial Properties

In this paper, self-synthesized TiO2 nanoparticle was used as a coating material with the addition of polydimethylsiloxane (PDMS) on the surface of the glass and ceramic substrate via spray coating. The self-cleaning properties of the coating with photocatalytic activity mechanism were observed under irradiation of black lamp as well as surface wettability. The antimicrobial properties and the morphology under a scanning electron microscope were also investigated. The results showed that the coating exhibited self-cleaning properties, as demonstrated by the photocatalytic degradation of methylene blue up to 80% and wettability as a super hydrophilic layer with a water contact angle less than 10° for both glass and ceramic substrate. The coating also shows an antimicrobial property by extending the radius of microbial growth up to 67% compared to the uncoated sample. 3% TiO2 addition with 50% w/w PDMS is the optimum coating ratio for maximum photocatalytic activity, super hydrophilic, and antimicrobial properties.

When more is more: redundant modifiers can facilitate visual search

According to the Gricean Maxim of Quantity, speakers provide the amount of information listeners require to correctly interpret an utterance, and no more (Grice in Logic and conversation, 1975). However, speakers do tend to violate the Maxim of Quantity often, especially when the redundant information improves reference precision (Degen et al. in Psychol Rev 127(4):591–621, 2020). Redundant (non-contrastive) information may facilitate real-world search if it narrows the spatial scope under consideration, or improves target template specificity. The current study investigated whether non-contrastive modifiers that improve reference precision facilitate visual search in real-world scenes. In two visual search experiments, we compared search performance when perceptually relevant, but non-contrastive modifiers were included in the search instruction. Participants (NExp. 1 = 48, NExp. 2 = 48) searched for a unique target object following a search instruction that contained either no modifier, a location modifier (Experiment 1: on the top left, Experiment 2: on the shelf), or a color modifier (the black lamp). In Experiment 1 only, the target was located faster when the verbal instruction included either modifier, and there was an overall benefit of color modifiers in a combined analysis for scenes and conditions common to both experiments. The results suggest that violations of the Maxim of Quantity can facilitate search when the violations include task-relevant information that either augments the target template or constrains the search space, and when at least one modifier provides a highly reliable cue. Consistent with Degen et al. (2020), we conclude that listeners benefit from non-contrastive information that improves reference precision, and engage in rational reference comprehension.Significance statementThis study investigated whether providing more information than someone needs to find an object in a photograph helps them to find that object more easily, even though it means they need to interpret a more complicated sentence. Before searching a scene, participants were either given information about where the object would be located in the scene, what color the object was, or were only told what object to search for. The results showed that providing additional information helped participants locate an object in an image more easily only when at least one piece of information communicated what part of the scene the object was in, which suggests that more information can be beneficial as long as that information is specific and helps the recipient achieve a goal. We conclude that people will pay attention to redundant information when it supports their task. In practice, our results suggest that instructions in other contexts (e.g., real-world navigation, using a smartphone app, prescription instructions, etc.) can benefit from the inclusion of what appears to be redundant information.

Incrementality and efficiency shape pragmatics across languages

To correctly interpret a message, people must attend to the context in which it was produced. Here we investigate how this process, known as pragmatic reasoning, is guided by two universal forces in human communication: incrementality and efficiency, with speakers of all languages interpreting language incrementally and making the most efficient use of the incoming information. Crucially, however, the interplay between these two forces results in speakers of different languages having different pragmatic information available at each point in processing, including inferences about speaker intentions. In particular, the position of adjectives relative to nouns (e.g., "black lamp" vs. "lamp black") makes visual context information available in reverse orders. In an eye-tracking study comparing four unrelated languages that have been understudied with regard to language processing (Catalan, Hindi, Hungarian, and Wolof), we show that speakers of languages with an adjective-noun order integrate context by first identifying properties (e.g., color, material, or size), whereas speakers of languages with a noun-adjective order integrate context by first identifying kinds (e.g., lamps or chairs). Most notably, this difference allows listeners of adjective-noun descriptions to infer the speaker's intention when using an adjective (e.g., "the black…" as implying "not the blue one") and anticipate the target referent, whereas listeners of noun-adjective descriptions are subject to temporary ambiguity when deriving the same interpretation. We conclude that incrementality and efficiency guide pragmatic reasoning across languages, with different word orders having different pragmatic affordances.

An intercomparison of CH&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt;O&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; measurements by fluorescence assay by gas expansion and cavity ring-down spectroscopy within HIRAC (Highly Instrumented Reactor for Atmospheric Chemistry)

Abstract. Simultaneous measurements of CH3O2 radical concentrations have been performed using two different methods in the Leeds HIRAC (Highly Instrumented Reactor for Atmospheric Chemistry) chamber at 295 K and in 80 mbar of a mixture of 3:1 He∕O2 and 100 or 1000 mbar of synthetic air. The first detection method consisted of the indirect detection of CH3O2 using the conversion of CH3O2 into CH3O by excess NO with subsequent detection of CH3O by fluorescence assay by gas expansion (FAGE). The FAGE instrument was calibrated for CH3O2 in two ways. In the first method, a known concentration of CH3O2 was generated using the 185 nm photolysis of water vapour in synthetic air at atmospheric pressure followed by the conversion of the generated OH radicals to CH3O2 by reaction with CH4∕O2. This calibration can be used for experiments performed in HIRAC at 1000 mbar in air. In the second method, calibration was achieved by generating a near steady state of CH3O2 and then switching off the photolysis lamps within HIRAC and monitoring the subsequent decay of CH3O2, which was controlled via its self-reaction, and analysing the decay using second-order kinetics. This calibration could be used for experiments performed at all pressures. In the second detection method, CH3O2 was measured directly using cavity ring-down spectroscopy (CRDS) using the absorption at 7487.98 cm−1 in the A←X (ν12) band with the optical path along the ∼1.4 m chamber diameter. Analysis of the second-order kinetic decays of CH3O2 by self-reaction monitored by CRDS has been used for the determination of the CH3O2 absorption cross section at 7487.98 cm−1, both at 100 mbar of air and at 80 mbar of a 3:1 He∕O2 mixture, from which σCH3O2=(1.49±0.19)×10-20 cm2 molecule−1 was determined for both pressures. The absorption spectrum of CH3O2 between 7486 and 7491 cm−1 did not change shape when the total pressure was increased to 1000 mbar, from which we determined that σCH3O2 is independent of pressure over the pressure range 100–1000 mbar in air. CH3O2 was generated in HIRAC using either the photolysis of Cl2 with UV black lamps in the presence of CH4 and O2 or the photolysis of acetone at 254 nm in the presence of O2. At 1000 mbar of synthetic air the correlation plot of [CH3O2]FAGE against [CH3O2]CRDS gave a gradient of 1.09±0.06. At 100 mbar of synthetic air the FAGE–CRDS correlation plot had a gradient of 0.95±0.024, and at 80 mbar of 3:1 He∕O2 mixture the correlation plot gradient was 1.03±0.05. These results provide a validation of the FAGE method to determine concentrations of CH3O2.

Fixed bed recirculation type photocatalytic reactor with TiO2 immobilized clay beads for the degradation of pesticide polluted water

A recirculation type photocatalytic reactor (RTPR), using ultraviolet radiations (Blue black lamp) and filled with titanium dioxide (TiO2) coated local clay beads, has been designed and used for the degradation of extremely toxic and water persistent pesticide Monocrotophos (MCP). Further, the present study has made an effort to use low cost, easily available, eco-friendly clay material as the support for the immobilization of catalyst for treating the pesticide polluted water by photocatalytic degradation. The economic viability of the developed reactor has been addressed in terms of electrical energy per order (EEO) for photocatalytic degradation of MCP, which is found to be very less compared to the literature values. The effect of various parameters like light conditions, recirculation rate, light intensity and initial MCP concentration has been determined for optimization of the designed RTPR. MCP degradation of 78.57% was obtained with optimum conditions as 25 mg/L MCP, 600 beads and pH 5. In addition to this, the recyclability of the immobilized TiO2 over clay beads in the developed RTPR was studied up to 30 continuous cycles without reactivation of catalyst. The mineralization of the MCP was studied using COD and was determined to be 73.75% and the degradation pathway is also proposed. Further, the degradation obeys pseudo first order kinetics.

Gas‐phase rate coefficients for a series of alkyl cyclohexanes with OH radicals and Cl atoms

AbstractThe rate coefficients of the reactions of OH radicals and Cl atoms with three alkylcyclohexanes compounds, methylcyclohexane (MCH), trans‐1,4‐dimethylcyclohexane (DCH), and ethylcyclohexane (ECH) have been investigated at (293 ± 1) K and 1000 mbar of air using relative rate methods. A majority of the experiments were performed in the Highly Instrumented Reactor for Atmospheric Chemistry (HIRAC), a stainless steel chamber using in situ FTIR analysis and online gas chromatography with flame ionization detection (GC‐FID) detection to monitor the decay of the alkylcyclohexanes and the reference compounds. The studies were undertaken to provide kinetic data for calibrations of radical detection techniques in HIRAC. The following rate coefficients (in cm3 molecule−1 s−1) were obtained for Cl reactions: k(Cl+MCH) = (3.51 ± 0.37) × 10–10, k(Cl+DCH) = (3.63 ± 0.38) × 10−10, k(Cl+ECH) = (3.88 ± 0.41) × 10−10, and for the reactions with OH radicals: k(OH+MCH) = (9.5 ± 1.3) × 10–12, k(OH+DCH) = (12.1 ± 2.2) × 10−12, k(OH+ECH) = (11.8 ± 2.0) × 10−12. Errors are a combination of statistical errors in the relative rate ratio (2σ) and the error in the reference rate coefficient. Checks for possible systematic errors were made by the use of two reference compounds, two different measurement techniques, and also three different sources of OH were employed in this study: photolysis of CH3ONO with black lamps, photolysis of H2O2 at 254 nm, and nonphotolytic trans‐2‐butene ozonolysis. For DCH, some direct laser flash photolysis studies were also undertaken, producing results in good agreement with the relative rate measurements. Additionally, temperature‐dependent rate coefficient investigations were performed for the reaction of methylcyclohexane with the OH radical over the range 273‐343 K using the relative rate method; the resulting recommended Arrhenius expression is k(OH + MCH) = (1.85 ± 0.27) × 10–11 exp((–1.62 ± 0.16) kJ mol−1/RT) cm3 molecule−1 s−1. The kinetic data are discussed in terms of OH and Cl reactivity trends, and comparisons are made with the existing literature values and with rate coefficients from structure‐activity relationship methods. This is the first study on the rate coefficient determination of the reaction of ECH with OH radicals and chlorine atoms, respectively.

Influence of bacterial, environmental and physical factors in design of photocatalytic reactors for water disinfection

The design of photocatalytic reactors for use in bacterial disinfection studies is often based on defined laboratory conditions, which are not a true representation of the harsh and ever-changing environment that bacteria encounter in nature. In this study four parameters (growth phase, biofilm production, pH and irradiation source) subject to continuous flux in nature, which could affect the efficacy of photocatalytic disinfection studies, were examined and their importance in process design was considered. The results produced a number of key findings which should be taken into consideration when designing photocatalytic reactors for biological processes. Using Escherichia coli as a model organism, studies of effects of pH and bacterial growth phase showed that cells in the stationary phase and at a pH of 8 were more resistant to photocatalytic breakdown. Only at a pH of 4 and while in the logarithmic growth phase, was complete photocatalytic destruction achieved. This process was further enhanced by replacing six 8 W black lamps with a single high-power UV-LED operated at 1.05 W. The impact of virulence was investigated by comparing photocatalytic destruction of a biofilm producing and non-producing strain of Staphylococcus epidermidis. The results indicated that there were no differences in susceptibility to disinfection suggesting that the capacity alone to express a virulence factor may not generate greater resistance to photocatalytic destruction.

Lamp black and hematite contribution to laser yellowing: A study on technical gypsum samples

Synthetic mixtures of gypsum/hematite and gypsum/lamp black at different concentrations are irradiated using a Q-switched Nd:YAG laser at 1064 nm. On irradiation, red to pink hematite-based mixtures turn either to a bright yellow and/or to black, while gray to black lamp black mixtures turn to pale yellow and/or gray depending on fluence and pigment concentration. Based on these results, artificial gypsum crusts with a microstructure very similar to the one of natural black crusts are produced from 1% hematite and 0.5% lamp black in hemihydrate. It is shown that these artificial crusts show a bulk discoloration on laser irradiation very similar to the one occasionally observed on laser-irradiated natural black crusts. A scanning electron microscope study of these artificial crust samples shows that irradiation residues distribute as nano-scale deposits on the surface of the individual gypsum crystals. Such artificial crusts are good substitutes for natural black crusts to study cleaning techniques. In the case of laser cleaning, they are able to scavenge a significant amount of irradiation by-products, and thus provide an interesting material to further study the laser-induced yellow effect on natural gypsum crusts containing iron oxides and soot.

Decomposition of Organic Chemicals in the Air and Inactivation of Aerosol-Associated Influenza Infectivity by Photocatalysis

Efficiency of photocatalysis depends on the surface area and materials, and we have prepared a porous ceramic substrate coated with nanosized-TiO2 for a photocatalytic air cleaner. The surface of the porous ceramic was coated with nano-sized TiO2 and total surface area of the board (30 × 30 × 1 cm) was 7,432 m2, being 14,864 m2 as the total area in the cleaner consisting of two boards and intervened black lamps. Eighty percent of 5 ppm acetaldehyde was decomposed and generated 8 ppm of carbon dioxide for 3 hours efficiently and continuously by passing through the TiO2-coated ceramic (5 × 10 × 1 cm) under black light. Particulate dioxins (40 pg/m3) and gaseous dioxins (16 pg/m3) were removed by 7.5 and 2.8 pg/m3 by passing through four TiO2-coated ceramic (30 × 30 × 2 cm) under black-light, indicating about 80% of dioxin was decomposed by the photocatalysis. This photocatalysis system was applied for inactivation of influenza aerosol. Influenza infection is spread efficiently by inhalation of aerosol-associated influenza virus. The aerosol-associated infectivity produced by nebulizer in a 754 liter cubic space was more than 10,000 plaque-forming units and was detectable for up to 30 minutes. The aerosol-associated infectivity of influenza virus was eliminated within five minutes by a photocatalytic air cleaner. The infectious aerosol-associated influenza would accumulate by the continuous production by cough and sneeze in the closed space, resulting in the efficient influenza infection. Thus a photocatalytic air cleaner efficiently decomposed organic chemicals including acetaldehyde and dioxins and inactivated aerosol-associated influenza virus infectivity.

PCBs의 광화학적 연구: NaOH 및 휴믹산 (humic acid, HA)에 의한 분해특성

Objectives: This study was carried out to examine whether the apparent photolysis with or without sensitizers [NaOH and humic acid (HA)] was prompted photodegradation of polychlorinated biphenyl (PCB) in aqueous solution. Methods: PCBs photodegradation occurred using fluorescence black lamps at <TEX>${\lambda}_{max}=300nm$</TEX>. PCB congeners were exposed in 10 ppm HA or 0.05N NaOH solutions, to investigate the decreasing profile of PCB concentration with time. The PCBs were then analyzed by gas chromatography/mass spectrometry (GC-MS). Reductive degradation profile of PCB congeners in the presence of both sensitizers under oxygen-saturated protic conditions was described using the wind-rose diagrams. Results: Use of HA or NaOH decreased PCB concentration with time in the dark and on irradiation, indicating that photolysis underwent through reductive dechlorination through energy transfer and possibly with reactive oxygens. The dechlorination was marked by a chromatographic shift, observed in the GC-MS plots. Therefore it is logical to assume that increasing the dose of sensitizers would increase the photodegradation rates of PCBs. The half-lives of pentachloro-PCB (penta-3) in 0.05N NaOH and 10 ppm HA were estimated at about 47 hours and 39 hours, respectively, under the same experimental conditions of photolysis. It was found that the rate of photolysis of pentachloro-PCB in aqueous solution followed apparent first-order kinetics compared to other congeners. Conclusion: Photochemical degradation (using 328 nm UV light) of penta- and hexa-PCBs in HA or alkaline solution is a viable method for pretreatment method. The results are helpful for the further comprehension of the reaction mechanism for photolytic dechlorination of PCBs in aquatic system.

Design and characterization of a smog chamber for studying gas-phase chemical mechanisms and aerosol formation

Abstract. We describe here characterization of a new state-of-the-art smog chamber facility for studying atmospheric gas-phase and aerosol chemistry. The chamber consists of a 30 m3 fluorinated ethylene propylene (FEP) Teflon film reactor housed in a temperature-controlled enclosure equipped with black lamps as the light source. Temperature can be set in the range from −10 to 40 °C at accuracy of ±1 °C as measured by eight temperature sensors inside the enclosure and one just inside the reactor. Matrix air can be purified with non-methane hydrocarbons (NMHCs) &lt; 0.5 ppb, NOx/O3/carbonyls &lt; 1 ppb and particles &lt; 1 cm−3. The photolysis rate of NO2 is adjustable between 0 and 0.49 min−1. At 298 K under dry conditions, the average wall loss rates of NO, NO2 and O3 were measured to be 1.41 × 10−4 min−1, 1.39 × 10−4 min−1 and 1.31 × 10−4 min−1, respectively, and the particle number wall loss rate was measured to be 0.17 h−1. Auxiliary mechanisms of this chamber are determined and included in the Master Chemical Mechanism to evaluate and model propene–NOx–air irradiation experiments. The results indicate that this new smog chamber can provide high-quality data for mechanism evaluation. Results of α-pinene dark ozonolysis experiments revealed secondary organic aerosol (SOA) yields comparable to those from other chamber studies, and the two-product model gives a good fit for the yield data obtained in this work. Characterization experiments demonstrate that our Guangzhou Institute of Geochemistry, Chinese Academy Sciences (GIG-CAS), smog chamber facility can be used to provide valuable data for gas-phase chemistry and secondary aerosol formation.

Study of the Atmospheric Chemistry of 2-Formylcinnamaldehyde

2-Formylcinnamaldehyde is a significant product of the reaction of naphthalene with OH radicals, and its photolysis and gas-phase reactions with O3, NO3 radicals, and OH radicals have been investigated in this work. 2-Formylcinnamaldehyde was observed to undergo photolysis by black lamps, with a photolysis rate of 0.14 × J(NO2), where J(NO2) is the NO2 photolysis rate. The measured rate constants for the reactions of 2-formylcinnamaldehyde with O3, NO3 radicals, and OH radicals (in units of cm(3) molecule(-1) s(-1)) were 1.8 × 10(-18), 4.3 × 10(-14), and 2.1 × 10(-11), respectively, with those for the O3 and NO3 reactions being for the E-isomer. 2-Formylcinnamaldehyde was observed to undergo significant adsorption and desorption from the reaction chamber Teflon film walls, and the photolysis rate and rate constants are subject to significant uncertainties. In the atmosphere, the dominant chemical loss processes for 2-formylcinnamaldehyde will be photolysis during daylight hours and reaction with NO3 radicals during nighttime. Phthaldialdehyde and glyoxal were observed as products of the OH radical and O3 reactions, and photolysis of E-2-formylcinnamaldehyde led to formation of Z-2-formylcinnamaldehyde plus two other molecular weight 160 isomers. The present results are compared with previous literature data, and reaction mechanisms are discussed.

Pyrometry using CCD cameras

The method of measurement of the surface brightness temperature distribution in high-enthalpy wind tunnels using CCD cameras is described. The problems of the operating wavelength selection, CCD camera metrology, and camera calibration by a black body and temperature lamps, as well as the possibility of LED reference etalon usage for correction of optical channel transmission variation are discussed. It is proposed to measure the emission spectrum of the surface under investigation for brightness pyrometry validation and for surface emissivity evaluation.

Aquatic plant inspired hierarchical artificial leaves for highly efficient photocatalysis

The natural leaf provides a superior template for engineering the artificial leaf in order to perform light energy conversion. To adapt to the aquatic environments, the aquatic plant leaves usually are thin and soft with excellent mass transportation and light-harvesting capability. In this report, the aquatic leaf is directly employed as a template to construct bioinspired hierarchical photocatalyst while mesoporous directing agent act as a second template. The dual templates consequently ensure the obtained TiO2 with optimal light harvesting structure, high surface area and excellent mass transportation, which contribute to improve photocatalytic capability. Specially, SiO2 is also introduced to form TiO2–SiO2 composite in the final hierarchical replica in order to improve the stability of mesostructures, perfect replication of leaves' fine structures and the dye adsorption capability for facilitating photodegradation. Consequently, the photocatalytic activity of the as-synthesized leaf replicas in the photodegradation of methylene blue is ca. 3 times higher than that of P25, and one order of magnitude higher than that of common nanocrystalline TiO2, under commercial black lamp irradiation.

Reductive Dechlorination of PCBs Using Photocatalyzed UV Light

AbstractFeasibility of photocatalytic dechlorination of PCB‐138 and Aroclor‐1254 using platinum loaded TiO2 (P25) in an alkaline 2‐propanol medium has been investigated. Experiments were conducted in batch mode using a Rayonet photo‐reactor under aerated and deaerated conditions with black lamps emitting around 350 nm as light source. Two forms of platinum deposition were investigated: Photochemically loaded P25 as well as addition of potassium hexachloroplatinate into the reaction medium. Partial dechlorination of PCBs was observed after 7 h of irradiation with pure TiO2 as catalyst when the reaction vessel was kept open to air. Complete dechlorination was observed after 5 h of irradiation in a deaerated environment. Enhanced photocatalytic efficiency was observed when platinum deposited P25 was used as catalyst, with the best result being obtained when aqueous potassium hexachloroplatinate was added into the reaction medium. Lower potassium hexachloroplatinate concentration (0.1 mM) yielded better performance.

Design and Characterization of a Two-Stage Human Subject Exposure Chamber

ABSTRACT A human subject exposure chamber, designed to hold six to eight subjects, coupled to an approximately 30-m3 Teflon reaction bag was designed and built to provide exposures that mimic the production and photochemical oxidation of atmospheric pollutants resulting from the combustion of coal or wood from a stove. The combustion products are introduced into the Teflon bag under atmospheric conditions. Photochemical oxidation of this mixture is accomplished by exposure to tropospheric sun-like radiation from an array of ultraviolet and black lamps. The aerosol in the Teflon reaction bag is then transferred into the exposure room to maintain a constant, lower exposure level. Continuous and semicontinuous monitoring of the gas and particulate matter (PM) pollution in the exposure room and the reaction bag is accomplished using a suite of instruments. This suite of instruments allows for the measurement of the concentrations of total and nonvolatile PM, nitric oxide, nitrogen dioxide, carbon monoxide, carbon dioxide, and ozone. The concentration of the particles was monitored by an R&P tapered element oscillating microbalance monitor. The chemical composition of the PM and its morphological characterization is accomplished by collecting samples in filter packs and conducting ion chromatography, elemental X-ray fluorescence, and scanning electron microscopy analyses. The concentration and composition of emissions from combustion of wood and coal is described. The results of this study suggest that although the bulk compositions of particulate emissions from the combustion of coal or wood in a stove have many similarities, the wood smoke aerosol is photochemically reactive, whereas the coal smoke aerosol is not. IMPLICATIONS The presence of high concentrations of PM and ozone in air has been linked to exacerbation of cardiovascular and cerebrovascular health problems. This manuscript describes the design of a human subject exposure chamber that allows for the production and control of PM and atmospherically important gases and characterizes pollutants present in the exposure chamber from the combustion of wood and coal. Fresh and photochemically aged pollutants are characterized. The chamber thus allows for studies to be conducted to quantify the effects of short-term PM and gas exposure on human subjects.

CAPTURA DE Tuta absoluta (Meyrick) (LEPIDOPTERA: GELECHIIDAE) COM ARMADILHA LUMINOSA NA CULTURA DO TOMATEIRO TUTORADO

The tomato leafminer (Tuta absoluta) represents a serious problem for the tomato crop, not only due to the intensity of its attack, but also to its occurrence during all the crop cycle. In Brazil, this pest has been controlled almost exclusively with insecticides, what is undesirable for economic and environmental reasons. In order to get more information on the control of this pest this research was carried out, in Ouro Verde (Goias State, Brazil), from September through October 2002, to evaluate the use of light traps for capture of adult T. absoluta specimens. The treatments used were: 1) black lamp; 2) BLB lamp; 3) Grolux lamp; and 4) fluorescent daylight lamp. The experimental design used was randomized complete blocks with four replications. The parameter to evaluate treatment capture efficiency was the counting of the adult T. absoluta specimens trapped. The results showed that the BLB and ultraviolet lamps were the most efficient treatments. Therefore, both can help to control the tomato leafminer in integrated pest management programs. KEY-WORDS: Tomato pinworm; integrated pest management; tomato.

실내 미생물 입자 살균을 위한 광촉매 기술의 효율

The current study evaluated the technical feasibility of the application of titanium dioxide () photo-catalytic air cleaners for the disinfection of bioaerosols present in indoor air. The evaluation included both laboratory and field tests and the tests of hydraulic diameter (HD) and lamp type (LT). Disinfection efficiency of photocatalytic oxidation (PCO) technique was estimated by survival ratio of bacteria or fungi calculated from the number of viable cells which form colonies on the nutrient agar plates. It was suggested that the reactor coating with did not enhance the adsorption of bioaerosols, and that the UV irradiation has certain extent of disinfection efficiency. The disinfection efficiency increased as HD decreased, most likely due to the decrease in the light intensity since the distance of the catalyst from the light source increased when increasing the HD. It was further suggested that the mass transfer effects were not as important as the light intensity effects on the PCO disinfection efficiency of bioaerosols. Germicidal lamp was superior to the black lamp for the disinfection of airborne bacteria and fungi, which is supported by the finding that the disinfection efficiencies were higher when the germicidal lamp was used compared to the black lamp in the laboratory test. These findings, combined with operational attributes such as a low pressure drop across the reactor and ambient temperature operation, can make the PCO reactor a possible tool in the effort to improve indoor bioaerosol levels.