Auto-Oxidation of a Volatile Silicon Compound: A Theoretical Study of the Atmospheric Chemistry of Tetramethylsilane

2020 ◽  
Author(s):  
Gabriel da Silva ◽  
Zhonghua Ren
Keyword(s):  
Atmospheric Chemistry ◽  
Kinetic Modelling ◽  
Major Product ◽  
Photochemical Oxidation ◽  
Silicon Compound ◽  
Indoor Environments ◽  
Radical Initiation ◽  
Alkoxyl Radical ◽  
Silicon Compounds ◽  
Indoor And Outdoor Environments

Volatile silicon compounds (VOSiCs) are air pollutants present in both indoor and outdoor environments. Here, tetramethylsilane (TMS) is selected as a model to study the photochemical oxidation mechanisms for VOSiCs using ab initio and RRKM theory / master equation kinetic modelling. Under tropospheric conditions the TMS radical (CH3)3SiCH2• reacts with O2 to produce a stabilized peroxyl radical which is expected to ultimately yield the alkoxyl radical (CH3)3SiCH2O•. At combustion-relevant temperatures, however, a well-skipping reaction to (CH3)3SiO• + HCHO dominates. Importantly, the (CH3)3SiCH2O• radical is predicted to rearrange to (CH3)3SiOCH2• with a very low reaction barrier, enabling an auto-oxidation process involving addition of a second O2. Subsequent oxidation reaction mechanisms of (CH3)3SiOCH2• have been developed, with the major product predicted to be the ester (CH3)3SiOCHO, an experimentally observed TMS oxidation product. The production of substantially oxygenated compounds following a single radical initiation reaction has implications for the ability of VOSiCs to contribute to ozone and particle formation in both outdoor and indoor environments.<br>

Auto-Oxidation of a Volatile Silicon Compound: A Theoretical Study of the Atmospheric Chemistry of Tetramethylsilane

2020 ◽  
Author(s):  
Gabriel da Silva ◽  
Zhonghua Ren
Keyword(s):  
Atmospheric Chemistry ◽  
Kinetic Modelling ◽  
Major Product ◽  
Photochemical Oxidation ◽  
Silicon Compound ◽  
Indoor Environments ◽  
Radical Initiation ◽  
Alkoxyl Radical ◽  
Silicon Compounds ◽  
Indoor And Outdoor Environments

Volatile silicon compounds (VOSiCs) are air pollutants present in both indoor and outdoor environments. Here, tetramethylsilane (TMS) is selected as a model to study the photochemical oxidation mechanisms for VOSiCs using ab initio and RRKM theory / master equation kinetic modelling. Under tropospheric conditions the TMS radical (CH3)3SiCH2• reacts with O2 to produce a stabilized peroxyl radical which is expected to ultimately yield the alkoxyl radical (CH3)3SiCH2O•. At combustion-relevant temperatures, however, a well-skipping reaction to (CH3)3SiO• + HCHO dominates. Importantly, the (CH3)3SiCH2O• radical is predicted to rearrange to (CH3)3SiOCH2• with a very low reaction barrier, enabling an auto-oxidation process involving addition of a second O2. Subsequent oxidation reaction mechanisms of (CH3)3SiOCH2• have been developed, with the major product predicted to be the ester (CH3)3SiOCHO, an experimentally observed TMS oxidation product. The production of substantially oxygenated compounds following a single radical initiation reaction has implications for the ability of VOSiCs to contribute to ozone and particle formation in both outdoor and indoor environments.<br>

scholarly journals The atmospheric chemistry of indoor environments

2020 ◽  
Vol 22 (1) ◽  
pp. 25-48 ◽  
Author(s):  
Jonathan P. D. Abbatt ◽  
Chen Wang
Keyword(s):  
Atmospheric Chemistry ◽  
Review Article ◽  
Indoor Environments

The review article summarizes the wide variety of atmospheric chemistry phenomena that occur indoors.

scholarly journals Assessing public perceptions about road lighting in five neighborhoods of Tirana, Albania

2019 ◽  
Vol 21 (2) ◽  
pp. 38-46 ◽  
Author(s):  
Kuenda Laze
Keyword(s):  
Obstacle Detection ◽  
Capital City ◽  
Lecture Hall ◽  
Indoor Environments ◽  
Visual Comfort ◽  
Road Lighting ◽  
Quality Aspects ◽  
Outdoor Environments ◽  
Indoor And Outdoor Environments ◽  
Indoor And Outdoor

The light use was assessed in ten indoor and outdoor environments of Tirana, Albania, in November 2017. The five indoor environments presented one lecture hall, one library and three labs in a school environment. The five major streets of the capital city of Tirana presented outdoor environments. Questionnaires were respectively used to assess two criteria of “Vista” and “Visual comfort” of daylight in indoor environments and security, obstacle detection and visibility in outdoor environments. Lighting quality aspects of “Vista” were evaluated at a higher rank compared to “Visual comfort”. The approximately 87 and 60 percent of respondents respectively were not able to detect a pavement obstacle after the sunset (dark) or to distinguish a familiar face at a distance of 5 and 10 m in outdoor environments. Lighting was respectively inadequately comfort to 86 percent of users in five indoor environments. Road lighting after dark was not satisfactory to 60 percent of respondents in outdoor environments. These initial findings identify that lighting could generally be inadequate in indoor and outdoor environments in Tirana. Further research is required on the light use in built environments in Tirana, Albania.

scholarly journals Transmission of SARS-CoV-2 Indoor and Outdoor Environments

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1640
Author(s):  
Xueli Xu ◽  
Jing Zhang ◽  
Liting Zhu ◽  
Qiansheng Huang
Keyword(s):  
Human Life ◽  
Indoor Environments ◽  
Property A ◽  
The World ◽  
Outdoor Environments ◽  
Other Substances ◽  
Indoor And Outdoor Environments ◽  
Solid Liquid ◽  
Great Damage ◽  
Indoor And Outdoor

Since the outbreak in late December 2019, the coronavirus disease 2019 (COVID-19) pandemic has spread across the globe, causing great damage to human life and property. A lot of researchers around the world have devoted themselves to the study of its origin, pathogenic mechanism, and transmission route, and this article gives a summary. First, both humans and animals can act as the host of coronavirus. In indoor environments, the virus may exist in aerosols, droplets, saliva, etc., from the nose and mouth connected to the respiratory system, as well as feces, urine, etc., from the digestive and urinary systems. In addition, other substances, such as breast milk, eye feces, and blood, released from the host can carry viruses. The virus transmitted indoors is affected by indoor machinery, natural forces, and human activities, and spreads in different distances. Second, the virus spreads outdoors through three kinds of media: solid, liquid, and gas, and is affected by their survival time, the temperature, and humidity in the environment.

scholarly journals Path-loss modelling for WSN deployment in indoor and outdoor environments for medical applications

2018 ◽  
Vol 7 (3) ◽  
pp. 1666 ◽  
Author(s):  
Ahmed Bashar Fakhri ◽  
Sadik Kamel Gharghan ◽  
Saleem Latteef Mohammed
Keyword(s):  
Standard Deviation ◽  
Multipath Propagation ◽  
Path Loss ◽  
Medical Application ◽  
Indoor Environments ◽  
Data Packets ◽  
And Performance ◽  
Log Normal ◽  
Loss Modelling ◽  
Indoor And Outdoor Environments

Wireless sensor networks (WSNs) and their applications have received significantly interested in the last few years. In WSN, knowing an accurate path-loss model as well as packet delivery should be taken into account for the successful distribution of several nodes in the net-work. This paper presents a path-loss modeling and performance evaluation of the ZigBee wireless standard. Received signal strength indi-cator (RSSI) measurements were achieved in outdoor and indoor environments to derive the path-loss based on Log-Normal Shadowing Model (LNSM). The path-loss parameters such as standard deviation and path loss exponents were estimated over point-to-point ZigBee WSN. In addition, the variances of received RSSI values and standard deviation for these values have been investigated. Furthermore, the data packets received is measured practically. Results revealed that the LNSM can be estimated to reflect the channel losses in both outdoor and indoor environments for medical application. The data delivery was achieved successfully of 100% in outdoor which better than indoor due to multipath propagation and shadowing. Moreover, the data packets delivery of the current work outperformed previous work.  

scholarly journals Seamless Indoor-Outdoor Navigation based on GNSS, INS and Terrestrial Ranging Techniques

2017 ◽  
Vol 70 (6) ◽  
pp. 1183-1204 ◽  
Author(s):  
Wei Jiang ◽  
Yong Li ◽  
Chris Rizos ◽  
Baigen Cai ◽  
Wei Shangguan
Keyword(s):  
Navigation System ◽  
Global Navigation Satellite Systems ◽  
Indoor Environments ◽  
Integrated Navigation ◽  
Satellite Systems ◽  
Integrated Navigation System ◽  
Outdoor Environments ◽  
Federated Kalman Filter ◽  
Indoor And Outdoor Environments ◽  
Global Navigation Satellite

We describe an integrated navigation system based on Global Navigation Satellite Systems (GNSS), an Inertial Navigation System (INS) and terrestrial ranging technologies that can support accurate and seamless indoor-outdoor positioning. To overcome severe multipath disturbance in indoor environments, Locata technology is used in this navigation system. Such a “Locata-augmented” navigation system can operate in different positioning modes in both indoor and outdoor environments. In environments where GNSS is unavailable, e.g. indoors, the proposed system is designed to operate in the Locata/INS “loosely-integrated” mode. On the other hand, in outdoor environments, all GNSS, Locata and INS measurements are available, and all useful information can be fused via a decentralised Federated Kalman filter. To evaluate the proposed system for seamless indoor-outdoor positioning, an indoor-outdoor test was conducted at a metal-clad warehouse. The test results confirmed that the proposed navigation system can provide continuous and reliable position and attitude solutions, with the positioning accuracy being better than five centimetres.

scholarly journals ACCURATE VISUAL LOCALIZATION IN OUTDOOR AND INDOOR ENVIRONMENTS EXPLOITING 3D IMAGE SPACES AS SPATIAL REFERENCE

2018 ◽  
Vol XLII-1 ◽  
pp. 355-362 ◽  
Author(s):  
D. Rettenmund ◽  
M. Fehr ◽  
S. Cavegn ◽  
S. Nebiker
Keyword(s):  
Coordinate Frame ◽  
Visual Localization ◽  
Indoor Environments ◽  
Test Field ◽  
3D Image ◽  
Single Image ◽  
Outdoor Environments ◽  
Indoor And Outdoor Environments ◽  
Localization Approach ◽  
Research Show

<p><strong>Abstract.</strong> In this paper, we present a method for visual localization and pose estimation based on 3D image spaces. The method works in indoor and outdoor environments and does not require the presence of control points or markers. The method is evaluated with different sensors in an outdoor and an indoor test field. The results of our research show the viability of single image localization with absolute position accuracies at the decimetre level for outdoor environments and 5 cm or better for indoor environments. However, the evaluation also revealed a number of limitations of single image visual localization in real-world environments. Some of them could be addressed by an alternative AR-based localization approach, which we also present and compare in this paper. We then discuss the strengths and weaknesses of the two approaches and show possibilities for combining them to obtain accurate and robust visual localization in an absolute coordinate frame.</p>

Providing Outdoor and Indoor Ubiquity with WLANs

2011 ◽  
pp. 1155-1168
Author(s):  
Diana Bri ◽  
Hugo Coll ◽  
Sandra Sendra ◽  
Jaime Lloret
Keyword(s):  
Local Area ◽  
High Gain ◽  
Point Of View ◽  
Indoor Environments ◽  
Research Areas ◽  
Outdoor Environments ◽  
Analytical Point ◽  
Wireless Interfaces ◽  
Indoor And Outdoor Environments ◽  
Indoor And Outdoor

Wireless Local Area Networks are very useful for the most applications based on network. Nowadays, these types of networks are the most powerful in the communication’s world. It can be developed in almost all environments and products are cheap and robust. Moreover, these networks can be formed by different devices with wireless interfaces like IP cameras, laptops, PDAs, sensors, etc. WLANs provide high bandwidth at large coverage areas (if high gain antennas are used), which it is necessary in many applications at different research areas. All these characteristics let WLANs be a useful technology to provide ubiquity for any type of service. If they are deployed from a good and exhaustive design, they can provide connection to any device, everywhere at anytime. In this paper we present a complete guideline about how to design and deploy WLANs and to get their best performance. We start from an analytical point of view and we use mathematical expressions to design WLANs in both indoor and outdoor environments. Then, we show a method proposed by some authors of this paper some years ago and how it can be used to design WLANs in indoor environments. Next, we show WLANs design in outdoor environments. Finally, we describe two projects developed by the authors of this chapter in order to provide ubiquity in real indoor and outdoor environments.

scholarly journals Underrated primary biogenic origin and lifetime of atmospheric formic and acetic acid

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xinqing Lee ◽  
Daikuan Huang ◽  
Qi Liu ◽  
Xueyan Liu ◽  
Hui Zhou ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Atmospheric Chemistry ◽  
Isotope Composition ◽  
Stable Carbon Isotope ◽  
Photochemical Oxidation ◽  
Long Distance ◽  
Biogenic Emission ◽  
Model Studies ◽  
Long Distance Transport ◽  
Strong Source

AbstractFormic and acetic acids are ubiquitous in the troposphere, playing an important role in the atmospheric chemistry. Recent model studies ended up with substantial low bias on their tropospheric budgets presumably due to a large missing biogenic source derived most likely from photochemical oxidation of long-lived volatile organic compound(s), i.e., a secondary biogenic emission. Here, by studying the stable carbon isotope composition of formic and acetic acid in couple in the troposphere and relevant sources, we find the gap relates to primary biogenic emission and atmospheric lifetime of the acids. We show the primary biogenic emission is only second to the secondary biogenic emission as a strong source. Marine emission is the least one yet present in all the tropospheric environments except some local air. Long-distance transport of this origin indicates the lifetime over 5 days for both acids. Our results indicate that recent simulations underrated both primary biogenic emission and the lifetime. These underestimations would inevitably bias low the modeled results, especially in the low and free troposphere where primary biogenic emission and lifetime has the most pronounced influence, respectively.

scholarly journals Interference from alkenes in chemiluminescent NO<sub><i>x</i></sub> measurements

2020 ◽  
Vol 13 (11) ◽  
pp. 5977-5991
Author(s):  
Mohammed S. Alam ◽  
Leigh R. Crilley ◽  
James D. Lee ◽  
Louisa J. Kramer ◽  
Christian Pfrang ◽  
...  
Keyword(s):  
Air Quality ◽  
Atmospheric Chemistry ◽  
Systematic Investigation ◽  
Atmospheric Pollutants ◽  
Quality Monitoring ◽  
Ozone Production ◽  
Atmospheric Composition ◽  
Anthropogenic Sources ◽  
Indoor Environments ◽  
Air Quality Monitoring

Abstract. Nitrogen oxides (NOx=NO+NO2) are critical intermediates in atmospheric chemistry and air pollution. NOx levels control the cycling and hence abundance of the primary atmospheric oxidants OH and NO3 and regulate the ozone production which results from the degradation of volatile organic compounds (VOCs) in the presence of sunlight. They are also atmospheric pollutants, and NO2 is commonly included in air quality objectives and regulations. NOx levels also affect the production of the nitrate component of secondary aerosol particles and other pollutants, such as the lachrymator peroxyacetyl nitrate (PAN). The accurate measurement of NO and NO2 is therefore crucial for air quality monitoring and understanding atmospheric composition. The most commonly used approach for the measurement of NO is the chemiluminescent detection of electronically excited NO2 (NO2∗) formed from the NO + O3 reaction within the NOx analyser. Alkenes, ubiquitous in the atmosphere from biogenic and anthropogenic sources, also react with ozone to produce chemiluminescence and thus may contribute to the measured NOx signal. Their ozonolysis reaction may also be sufficiently rapid that their abundance in conventional instrument background cycles, which also utilises the reaction with ozone, differs from that in the measurement cycle such that the background subtraction is incomplete, and an interference effect results. This interference has been noted previously, and indeed, the effect has been used to measure both alkenes and ozone in the atmosphere. Here we report the results of a systematic investigation of the response of a selection of commercial NOx monitors to a series of alkenes. These NOx monitors range from systems used for routine air quality monitoring to atmospheric research instrumentation. The species-investigated range was from short-chain alkenes, such as ethene, to the biogenic monoterpenes. Experiments were performed in the European PHOtoREactor (EUPHORE) to ensure common calibration and samples for the monitors and to unequivocally confirm the alkene levels present (via Fourier transform infrared spectroscopy – FTIR). The instrument interference responses ranged from negligible levels up to 11 %, depending upon the alkene present and conditions used (e.g. the presence of co-reactants and differing humidity). Such interferences may be of substantial importance for the interpretation of ambient NOx data, particularly for high VOC, low NOx environments such as forests or indoor environments where alkene abundance from personal care and cleaning products may be significant.

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