scholarly journals Technical Note: Effect of varying the <i>λ</i> = 185 and 254 nm photon flux ratio on radical generation in oxidation flow reactors

2020 ◽  
Vol 20 (21) ◽  
pp. 13417-13424
Author(s):  
Jake P. Rowe ◽  
Andrew T. Lambe ◽  
William H. Brune
Keyword(s):  
Residence Time ◽  
Low Cost ◽  
Flux Ratio ◽  
Technical Note ◽  
Photon Flux ◽  
Oh Radicals ◽  
Flow Reactors ◽  
Series Of Experiments ◽  
Radical Generation ◽  
Smog Chambers

Abstract. Oxidation flow reactors (OFRs) complement environmental smog chambers as a portable, low-cost technique for exposing atmospheric compounds to oxidants such as ozone (O3), nitrate (NO3) radicals, and hydroxyl (OH) radicals. OH is most commonly generated in OFRs via photolysis of externally added O3 at λ=254 nm (OFR254) or combined photolysis of O2 and H2O at λ=185 nm plus photolysis of O3 at λ=254 nm (OFR185) using low-pressure mercury (Hg) lamps. Whereas OFR254 radical generation is influenced by [O3], [H2O], and photon flux at λ=254 nm (I254), OFR185 radical generation is influenced by [O2], [H2O], I185, and I254. Because the ratio of photon fluxes, I185:I254, is OFR-specific, OFR185 performance varies between different systems even when constant [H2O] and I254 are maintained. Thus, calibrations and models developed for one OFR185 system may not be applicable to another. To investigate these issues, we conducted a series of experiments in which I185:I254 emitted by Hg lamps installed in an OFR was systematically varied by fusing multiple segments of lamp quartz together that either transmitted or blocked λ=185 nm radiation. Integrated OH exposure (OHexp) values achieved for each lamp type were obtained using the tracer decay method as a function of UV intensity, humidity, residence time, and external OH reactivity (OHRext). Following previous related studies, a photochemical box model was used to develop a generalized OHexp estimation equation as a function of [H2O], [O3], and OHRext that is applicable for I185:I254≈0.001 to 0.1.

scholarly journals Technical Note: Effect of varying the λ = 185 and 254 nm photon flux ratio on radical generation in oxidation flow reactors

2020 ◽  
Author(s):  
Jake P. Rowe ◽  
Andrew T. Lambe ◽  
William H. Brune
Keyword(s):  
Residence Time ◽  
Low Cost ◽  
Flux Ratio ◽  
Technical Note ◽  
Photon Flux ◽  
Oh Radicals ◽  
Flow Reactors ◽  
Series Of Experiments ◽  
Radical Generation ◽  
Smog Chambers

Abstract. Oxidation flow reactors (OFRs) complement environmental smog chambers as a portable, low-cost technique for exposing atmospheric compounds to oxidants such as ozone (O3) and hydroxyl (OH) radicals. OH is most commonly generated in OFRs via photolysis of externally added O3 at λ = 254  nm (OFR254), or combined photolysis of O2 and H2O at λ = 185 nm plus photolysis of O3 at λ = 254 nm (OFR185) using low-pressure mercury (Hg) lamps. Whereas OFR254 radical generation is influenced by [O3], [H2O], and photon flux at λ = 254 nm (I254), OFR185 radical generation is influenced by [O2], [H2O], I185, and I254. Because the ratio of photon fluxes, I185 : I254, is OFR-specific, OFR185 performance varies between different systems even when constant H2O and I254 are maintained. Thus, calibrations and models developed for one OFR185 system may not be applicable to another. To investigate these issues, we conducted a series of experiments in which I185 : I254 emitted by Hg lamps installed in an OFR was systematically varied by fusing multiple segments of lamp quartz together that either transmitted or blocked 185 nm radiation. Integrated OH exposure (OHexp) values achieved for each lamp type were obtained using the tracer decay method as a function of UV intensity, humidity, residence time, and external OH reactivity (OHRext). Following previous related studies, a photochemical box model was used to develop a generalized OHexp estimation equation as a function of [H2O], [O3] and OHRext that is applicable for I185 : I254 &amp;approx; 0.001 to 0.1.

scholarly journals Estimation of the Inhaled Dose of Pollutants in Different Micro-Environments: A Systematic Review of the Literature

Toxics ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 140
Author(s):  
Francesca Borghi ◽  
Andrea Spinazzè ◽  
Simone Mandaglio ◽  
Giacomo Fanti ◽  
Davide Campagnolo ◽  
...  
Keyword(s):  
Systematic Review ◽  
Residence Time ◽  
Low Cost ◽  
Pulmonary Ventilation ◽  
Personal Exposure ◽  
Ventilation Rate ◽  
Atmospheric Pollutants ◽  
Active Commuting ◽  
Review Of The Literature ◽  
Future Studies

Recently, the need to assess personal exposure in different micro-environments has been highlighted. Further, estimating the inhaled dose of pollutants is considerably one of the most interesting parameters to be explored to complete the fundamental information obtained through exposure assessment, especially if associated with a dose-response approach. To analyze the main results obtained from the studies related to the estimation of the inhaled dose of pollutants in different micro-environments (environments in which an individual spends a part of his day), and to identify the influence of different parameters on it, a systematic review of the literature was performed. The principal outcomes from the considered studies outlined that (i) exposure concentration and residence time are among the most important parameters to be evaluated in the estimation of the inhaled dose, especially in transport environments. Further, (ii) the pulmonary ventilation rate can be of particular interest during active commuting because of its increase, which increases the inhalation of pollutants. From a methodological point of view, the advent of increasingly miniaturized, portable and low-cost technologies could favor these kinds of studies, both for the measurement of atmospheric pollutants and the real-time evaluation of physiological parameters used for estimation of the inhaled dose. The main results of this review also show some knowledge gaps. In particular, numerous studies have been conducted for the evaluation (in terms of personal exposure and estimation of the inhaled dose) of different PM fractions: other airborne pollutants, although harmful to human health, are less represented in studies of this type: for this reason, future studies should be conducted, also considering other air pollutants, not neglecting the assessment of exposure to PM. Moreover, many studies have been conducted indoors, where the population spends most of their daily time. However, it has been highlighted how particular environments, even if characterized by a shorter residence time, can contribute significantly to the dose of inhaled pollutants. These environments are, therefore, of particular importance and should be better evaluated in future studies, as well as occupational environments, where the work results in a high pulmonary ventilation rate. The attention of future studies should also be focused on these categories of subjects and occupational studies.

Simplified rat intubation using a new oropharyngeal intubation wedge

2000 ◽  
Vol 89 (5) ◽  
pp. 1766-1770 ◽  
Author(s):  
I-Ming Jou ◽  
Ya-Ting Tsai ◽  
Ching-Lin Tsai ◽  
Ming-Ho Wu ◽  
Han-Yu Chang ◽  
...  
Keyword(s):  
Low Cost ◽  
Vital Signs ◽  
Upper Airway ◽  
Postmortem Examination ◽  
Normal Range ◽  
Special Equipment ◽  
Vocal Cords ◽  
Oropharyngeal Cavity ◽  
Series Of Experiments ◽  
Proper Setting

Our new oropharyngeal intubation wedge made from a plastic 3-ml syringe has been used successfully for the expansion of the oropharyngeal cavity and visualization of vocal cords for endotracheal intubation in the rat. All the animals we used tolerated the intubation and ventilation procedures in a series of experiments. After the proper setting of the respirator, vital signs were maintained within normal range. The postmortem examination and measurements in the upper airway confirmed that the endotracheal tube was properly sited and also demonstrated the precise size of the device that should be used. The main advantages of this method include low cost, simplicity, and reliability. Furthermore, because no expensive, elaborate, difficult-to-operate, or hard-to-get special equipment is needed, this technique can be used in every laboratory.

scholarly journals A Cotton Module Feeder Plastic Contamination Inspection System

2020 ◽  
Vol 2 (2) ◽  
pp. 280-293
Author(s):  
Mathew G. Pelletier ◽  
Greg A. Holt ◽  
John D. Wanjura
Keyword(s):  
Mechanical Design ◽  
Low Cost ◽  
Processing System ◽  
Technical Note ◽  
Inspection System ◽  
Learning Program ◽  
Cotton Lint ◽  
Cotton Industry ◽  
Bill Of Materials ◽  
The U.S

The removal of plastic contamination in cotton lint is an issue of top priority to the U.S. cotton industry. One of the main sources of plastic contamination showing up in marketable cotton bales, at the U.S. Department of Agriculture’s classing office, is plastic from the module wrap used to wrap cotton modules produced by the new John Deere round module harvesters. Despite diligent efforts by cotton ginning personnel to remove all plastic encountered during unwrapping of the seed cotton modules, plastic still finds a way into the cotton gin’s processing system. To help mitigate plastic contamination at the gin; an inspection system was developed that utilized low-cost color cameras to see plastic on the module feeder’s dispersing cylinders, that are normally hidden from view by the incoming feed of cotton modules. This technical note presents the design of an automated intelligent machine-vision guided cotton module-feeder inspection system. The system includes a machine-learning program that automatically detects plastic contamination in order to alert the cotton gin personnel as to the presence of plastic contamination on the module feeder’s dispersing cylinders. The system was tested throughout the entire 2019 cotton ginning season at two commercial cotton gins and at one gin in the 2018 ginning season. This note describes the over-all system and mechanical design and provides an over-view and coverage of key relevant issues. Included as an attachment to this technical note are all the mechanical engineering design files as well as the bill-of-materials part source list. A discussion of the observational impact the system had on reduction of plastic contamination is also addressed.

scholarly journals Potential of Iron Pillared Clay as Active Nanocatalyst for Rapid Decolorization of Methylene Blue

2019 ◽  
Vol 7 (2) ◽  
pp. 46-53
Author(s):  
Lal hmunsiama ◽  
◽  
Seung-Mok Lee ◽  
Keyword(s):  
Methylene Blue ◽  
Iron Oxide ◽  
Aqueous Solutions ◽  
Low Cost ◽  
Analytical Data ◽  
Bentonite Clay ◽  
Pillared Clay ◽  
Oh Radicals ◽  
Heterogeneous Structure ◽  
Iron Oxide Particles

In this study, the iron-pillared clay nanocatalyst (ICN) was employed as a nanocatalyst for decolorization of methylene blue (MB) in aqueous solutions without hydrogen peroxide. The changes in clay structure after the incorporation of iron-oxide particles was studied with the help of XRD analytical data. The SEM micrographs showed higher heterogeneous structure of ICN compared to pristine clay and the specific surface area of ICN (82.54 m2/g) is considerably higher than the unmodified clay (63.41 m2/g). Further, the EDX analytical data indicate the successful incorporation of iron-oxide into bentonite clay. Batch experiments showed that ICN could degrade MB within pH 3.0 to 11.0 and it is efficient even at higher concentrations. The degradation is very fast and more than 90% is removed within 30 mins. A small amount of ICN is effective for degradation of MB and the reusability test showed that ICN can be reuse for several times for the degradation of MB in aqueous solutions. The effect of scavengers studies indicate that the ·OH radicals generated from the ICN are responsible in the degradation of MB. This study indicates that ICN must be low cost and environmentally friendly active nanocatalyst for degradation of MB present in aquatic environment.

scholarly journals Technical Note: Evaluation of a low-cost evaporation protection method for portable water samplers

2020 ◽  
Author(s):  
Jana von Freyberg ◽  
Julia L. A. Knapp ◽  
Andrea Rücker ◽  
Bjørn Studer ◽  
James W. Kirchner
Keyword(s):  
Water Samples ◽  
Low Cost ◽  
Isotopic Fractionation ◽  
Field Tests ◽  
Isotopic Signature ◽  
Technical Note ◽  
Stable Water Isotopes ◽  
Sample Collection ◽  
Protection Method ◽  
Cost Efficient

Abstract. Automated field sampling of streamwater or precipitation for subsequent analysis of stable water isotopes (2H and 18O) is often conducted with off-the-shelf automated samplers. However, water samples stored in the field for days and weeks in open bottles inside autosamplers undergo isotopic fractionation and vapor mixing, thus altering their isotopic signature. We therefore designed an evaporation protection method which modifies autosampler bottles using a syringe housing and silicone tube, and tested whether this method reduces evaporative fractionation and vapor mixing in water samples stored for up to 24 days in ISCO autosamplers (Teledyne ISCO., Lincoln, US). Laboratory and field tests under different temperature and humidity conditions showed that water samples in bottles with evaporation protection were far less altered by evaporative fractionation and vapor mixing than samples in conventional open bottles. Our design is a cost-efficient approach to upgrade the 1-litre sample bottles of ISCO 6712 Full-size Portable Samplers, allowing secure water sample collection in warm and dry environments. Our design can be readily adapted (e.g., by using a different syringe size) to fit the bottles used by many other field autosamplers.

scholarly journals Controlled nitric oxide production via O(<sup>1</sup>D)+N<sub>2</sub>O reactions for use in oxidation flow reactor studies

2017 ◽  
Author(s):  
Andrew Lambe ◽  
Paola Massoli ◽  
Xuan Zhang ◽  
Manjula Canagaratna ◽  
John Nowak ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Flow Reactor ◽  
Branching Ratio ◽  
Oxidation Products ◽  
Oh Radicals ◽  
Ionization Mass ◽  
Flow Reactors ◽  
Oxidative Aging ◽  
Gas Phase Oxidation

Abstract. Oxidation flow reactors that use low-pressure mercury lamps to produce hydroxyl (OH) radicals are an emerging technique for studying the oxidative aging of organic aerosols. Here, ozone (O3) is photolyzed at 254 nm to produce O(1D) radicals, which react with water vapor to produce OH. However, the need to use parts-per-million levels of O3 hinders the ability of oxidation flow reactors to simulate NOx-dependent SOA formation pathways. Simple addition of nitric oxide (NO) results in fast conversion of NOx (NO + NO2) to nitric acid (HNO3), making it impossible to sustain NO at levels that are sufficient to compete with hydroperoxy (HO2) radicals as a sink for organic peroxy (RO2) radicals. We developed a new method that is well suited to the characterization of NOx-dependent SOA formation pathways in oxidation flow reactors. NO and NO2 are produced via the reaction O(1D) + N2O→ 2NO, followed by the reaction NO + O3 → NO2+ O2. Laboratory measurements coupled with photochemical model simulations suggest that O(1D) + N2O reactions can be used to systematically vary the relative branching ratio of RO2 + NO reactions relative to RO2 + HO2 and/or RO2 + RO2 reactions over a range of conditions relevant to atmospheric SOA formation. We demonstrate proof of concept using high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) measurements with nitrate (NO3−) reagent ion to detect gas-phase oxidation products of isoprene and α-pinene previously observed in NOx-influenced environments and in laboratory chamber experiments.

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