scholarly journals Simulation of SOA formation from the photooxidation of monoalkylbenzenes in the presence of aqueous aerosols containing electrolytes under various NO<sub><i>x</i></sub> levels

2019 ◽  
Vol 19 (8) ◽  
pp. 5719-5735 ◽  
Author(s):  
Chufan Zhou ◽  
Myoseon Jang ◽  
Zechen Yu
Keyword(s):  
Organic Phase ◽  
Kinetic Mechanism ◽  
Model Parameters ◽  
Organic Nitrates ◽  
Phase Reaction ◽  
Reaction Rate Constants ◽  
The Difference ◽  
The Impact ◽  
Oxygenated Products ◽  
Aqueous Reactions

Abstract. The formation of secondary organic aerosols (SOAs) from the photooxidation of three monoalkylbenzenes (toluene, ethylbenzene, and n-propylbenzene) in the presence of inorganic seeds (SO42-–NH4+–H2O system) under varying NOx levels has been simulated using the Unified Partitioning Aerosol Phase Reaction (UNIPAR) model. The evolution of the volatility–reactivity distribution (mass-based stoichiometric coefficient, αi) of oxygenated products, which were created by the near-explicit gas kinetic mechanism, was integrated with the model using the parameters linked to the concentrations of HO2 and RO2 radicals. This dynamic distribution was used to estimate the model parameters related to the thermodynamic constants of the products in multiple phases (e.g., the gas phase, organic phase, and inorganic phase) and the reaction rate constants in the aerosol phase. The SOA mass was predicted through the partitioning and aerosol chemistry processes of the oxygenated products in both the organic phase and aqueous solution containing electrolytes, with the assumption of organic–inorganic phase separation. The prediction of the time series SOA mass (12 h), against the aerosol data obtained from an outdoor photochemical smog chamber, was improved by the dynamic αi set compared to the prediction using the fixed αi set. Overall, the effect of an aqueous phase containing electrolytes on SOA yields was more important than that of the NOx level under our simulated conditions or the utilization of the age-driven αi set. Regardless of the NOx conditions, the SOA yields for the three aromatics were significantly higher in the presence of wet electrolytic seeds than those obtained with dry seeds or no seed. When increasing the NOx level, the fraction of organic matter (OM) produced by aqueous reactions to the total OM increased due to the increased formation of relatively volatile organic nitrates and peroxyacyl-nitrate-like products. The predicted partitioning mass fraction increased as the alkyl chain length increased but the organic mass produced via aerosol-phase reactions decreased due to the increased activity coefficient of the organic compounds containing longer alkyl chains. Overall, the lower mass-based SOA yield was seen in the longer alkyl-substituted benzene in both the presence and absence of inorganic-seeded aerosols. However, the difference of mole-based SOA yields of three monoalkylbenzenes becomes small because the highly reactive organic species (i.e., glyoxal) mainly originates from ring opening products without an alkyl side chain. UNIPAR predicted the conversion of hydrophilic, acidic sulfur species to non-electrolytic dialkyl organosulfate (diOS) in the aerosol. Thus, the model predicted the impact of diOS on both hygroscopicity and acidity, which subsequently influenced aerosol growth via aqueous reactions.

scholarly journals Simulation of SOA Formation from the Photooxidation of Monoalkylbenzenes in the Presence of Aqueous Aerosols Containing Electrolytes under Various NO<sub><i>x</i></sub> Levels

2018 ◽  
Author(s):  
Chufan Zhou ◽  
Myoseon Jang ◽  
Zechen Yu
Keyword(s):  
Organic Phase ◽  
Kinetic Mechanism ◽  
Model Parameters ◽  
Organic Nitrates ◽  
Phase Reaction ◽  
Reaction Rate Constants ◽  
The Difference ◽  
The Impact ◽  
Oxygenated Products ◽  
Aqueous Reactions

Abstract. The formation of secondary organic aerosols (SOAs) from the photooxidation of three monoalkylbenzenes (toluene, ethylbenzene, and n-propylbenzene) in the presence of inorganic seeds (SO42−-NH4+-H2O system) under varying NOx levels has been simulated using the Unified Partitioning-Aerosol Phase Reaction (UNIPAR) model. The evolution of the volatility-reactivity distribution (mass-base stoichiometric coefficient, αi) of oxygenated products, which were created by the near-explicit gas kinetic mechanism, was integrated with the model using the parameters linked to the concentrations of HO2 and RO2 radicals. This dynamic distribution was applied to estimate the model parameters related to the thermodynamic constants of the products in multiple phases (e.g., the gas phase, organic phase, and inorganic phase) and the reaction rate constants in the aerosol phase. The SOA mass was predicted through the partitioning and aerosol chemistry processes of the oxygenated products in both the organic phase and aqueous solution containing electrolytes, with the assumption of organic-inorganic phase separation. The prediction of the time series SOA mass (12-hr), against the aerosol data obtained from an outdoor photochemical smog chamber, was improved by the dynamic αi set compared to the prediction using the fixed αi set. Overall, the effect of an aqueous phase containing electrolytes on SOA yields was more important than that of the NOx level under our simulated conditions or the utilization of the age-driven αi set. Regardless of the NOx conditions, the SOA yields for the three aromatics were significantly higher in the presence of wet electrolytic seeds than those obtained with dry seeds or no seed. When increasing the NOx level, the fraction of organic matter (OM) produced by aqueous reactions to the total OM increased due to the increased formation of relatively volatile organic nitrates and peroxyacyl nitrate like products. The predicted partitioning mass fraction increased as the alkyl chain length increases but the organic mass produced via aerosol phase reactions decreased due to the increased activity coefficient of the organic compounds containing longer alkyl chains. Overall, the lower mass-base SOA yield was seen in the longer alkyl-substituted benzene in both the presence and absence of inorganic seeded aerosols. However, the difference of mole-base SOA yields of three monoalkylbenzenes becomes small because the highly reactive organic species (i.e., glyoxal) mainly originates from ring opening products without alkyl side chain. UNIPAR predicted the conversion of hydrophilic, acidic sulfur species to non-electrolytic dialkyl-organosulfate (diOS) in the aerosol. Thus, the model predicted the impact of diOS on both hygroscopicity and acidity, which subsequently influenced aerosol growth via aqueous reactions.

scholarly journals Prediction of Secondary Organic Aerosol from the Multiphase Reaction of Gasoline Vapor by Using Volatility–Reactivity Base Lumping

2021 ◽  
Author(s):  
Sanghee Han ◽  
Myoseon Jang
Keyword(s):  
Secondary Organic Aerosol ◽  
Ambient Air ◽  
Organic Aerosol ◽  
Heterogeneous Reactions ◽  
Model Parameters ◽  
Phase Reaction ◽  
Atmospheric Aging ◽  
Gasoline Vapor ◽  
Before And After ◽  
The Impact

Abstract. The secondary organic aerosol (SOA) formation from photooxidation of gasoline vapor was simulated by using the UNIfied Partitioning Aerosol phase Reaction (UNIPAR) model, which predicted SOA growth via multiphase reactions of hydrocarbons. The Carbon Bond 6 (CB6r3) mechanism was incorporated with the SOA model to estimate the hydrocarbon consumption and the concentration of radicals (i.e., RO2 and HO2), which were closely related to atmospheric aging of gas products. Oxygenated products were lumped according to their volatilities and reactivity and linked to stoichiometric coefficients and their physicochemical parameters, which were dynamically constructed at different NOx levels and degrees of gas aging. To assess the gasoline SOA potential in ambient air, model parameters were corrected for gas–wall partitioning (GWP), which was predicted by a qualitative structure activity relationship for explicit products. The simulated gasoline SOA mass was evaluated against observed data obtained in the UF-APHOR chamber under ambient sunlight. The influence of environmental conditions on gasoline SOA was characterized under varying NOx levels, aerosol acidity, humidity, temperature, and concentrations of aqueous salts and gasoline vapor. Both the measured and simulated gasoline SOA formation was sensitive to seeded conditions (acidity and hygroscopicity) and NOx levels. A considerable difference in SOA mass appeared before and after efflorescence relative humidity in the presence of salted aqueous solution. SOA growth in the presence of aqueous reactions was more impacted by temperature than that in absence of seed. The impact of GWP on SOA formation was generally significant, and it appeared to be higher in the absence of wet salts. We conclude that the SOA model in the corpus with both heterogeneous reactions and the model parameters corrected for GWP is essential to accurately predict SOA mass in ambient air.

Evaluation of the impact of public investment programs on social and economic performance of territories

2019 ◽  
pp. 109-123
Author(s):  
I. E. Limonov ◽  
M. V. Nesena
Keyword(s):  
Bayesian Modeling ◽  
Positive Impact ◽  
Public Investment ◽  
Difference In Differences ◽  
The Public ◽  
Export Activity ◽  
Regional Investment ◽  
The Difference ◽  
The Impact ◽  
Development Institution

The purpose of this study is to evaluate the impact of public investment programs on the socio-economic development of territories. As a case, the federal target programs for the development of regions and investment programs of the financial development institution — Vnesheconombank, designed to solve the problems of regional development are considered. The impact of the public interventions were evaluated by the “difference in differences” method using Bayesian modeling. The results of the evaluation suggest the positive impact of federal target programs on the total factor productivity of regions and on innovation; and that regional investment programs of Vnesheconombank are improving the export activity. All of the investments considered are likely to have contributed to the reduction of unemployment, but their implementation has been accompanied by an increase in social inequality.

Estimating OLED Display Device Lifetime from pixel and screen brightness and its application

2019 ◽  
Vol 2019 (1) ◽  
pp. 331-338 ◽  
Author(s):  
Jérémie Gerhardt ◽  
Michael E. Miller ◽  
Hyunjin Yoo ◽  
Tara Akhavan
Keyword(s):  
Image Processing ◽  
Power Consumption ◽  
Model Parameters ◽  
Display Device ◽  
Image Processing Algorithm ◽  
Pixel Value ◽  
Device Lifetime ◽  
The Impact ◽  
Oled Display

In this paper we discuss a model to estimate the power consumption and lifetime (LT) of an OLED display based on its pixel value and the brightness setting of the screen (scbr). This model is used to illustrate the effect of OLED aging on display color characteristics. Model parameters are based on power consumption measurement of a given display for a number of pixel and scbr combinations. OLED LT is often given for the most stressful display operating situation, i.e. white image at maximum scbr, but having the ability to predict the LT for other configurations can be meaningful to estimate the impact and quality of new image processing algorithms. After explaining our model we present a use case to illustrate how we use it to evaluate the impact of an image processing algorithm for brightness adaptation.

The Use of Multimedia and its Impact on Bangladeshi EFL Learners at Tertiary Level

2020 ◽  
Vol 4 (2) ◽  
pp. 150
Author(s):  
Farzana Sharmin Pamela Islam
Keyword(s):  
Language Learning ◽  
Academic Writing ◽  
Teaching And Learning ◽  
English Language ◽  
Capital City ◽  
Tertiary Level ◽  
Language Classroom ◽  
The Difference ◽  
The Government ◽  
The Impact

As 21st century is the era of modern technologies with different aspects, it offers us to make the best use of them. After tape recorder and overhead projector (OHP), multimedia has become an important part of language classroom facilities for its unique and effective application in delivering and learning lesson. Although in many parts of Bangladesh, a South Asian developing country, where English enjoys the status of a foreign language, the use of multimedia in teaching and learning is viewed as a matter of luxury. However, nowadays the usefulness and the necessity of it are well recognized by the academics as well as the government. The study aims to focus on the difference between a traditional classroom void of multimedia and multimedia equipped classrooms at university level by explaining how multimedia support the students with enhanced opportunity to interact with diverse texts that give them more in-depth comprehension of the subject. It also focuses on audio-visual advantage of multimedia on the students’ English language learning. The study has followed a qualitative method to get an in-depth understanding of the impact of using multimedia in an English language classroom at tertiary level. For this purpose, the data have been collected from two different sources. Firstly, from students’ written response to  an open ended question as to their comparative experience of learning  lessons with and without multimedia facilities; and secondly, through  observation of English language classes at a private university of Dhaka, the capital city of Bangladesh. The discussion of the study is limited to  the use of multimedia in English language classroom using cartoons, images and music with a view to enhance students’ skills in academic writing, critical analysis of image and critical appreciation of music. For this purpose, cartoons in English language, images from Google and music from You Tube have got focused discussion in this paper.

Case study: Prediction and field tests of railway noise and effects of a low-height noise barrier

2020 ◽  
Vol 68 (4) ◽  
pp. 303-314
Author(s):  
Yuna Park ◽  
Hyo-In Koh ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
...  
Keyword(s):  
High Speed ◽  
Field Tests ◽  
Residential Areas ◽  
Railway Systems ◽  
Railway Noise ◽  
Sound Levels ◽  
Noise Barrier ◽  
The Difference ◽  
Reduction Effect ◽  
The Impact

Railway noise is calculated to predict the impact of new or reconstructed railway tracks on nearby residential areas. The results are used to prepare adequate counter- measures, and the calculation results are directly related to the cost of the action plans. The calculated values were used to produce noise maps for each area of inter- est. The Schall 03 2012 is one of the most frequently used methods for the production of noise maps. The latest version was released in 2012 and uses various input para- meters associated with the latest rail vehicles and track systems in Germany. This version has not been sufficiently used in South Korea, and there is a lack of standard guidelines and a precise manual for Korean railway systems. Thus, it is not clear what input parameters will match specific local cases. This study investigates the modeling procedure for Korean railway systems and the differences between calcu- lated railway sound levels and measured values obtained using the Schall 03 2012 model. Depending on the location of sound receivers, the difference between the cal- culated and measured values was within approximately 4 dB for various train types. In the case of high-speed trains, the value was approximately 7 dB. A noise-reducing measure was also modeled. The noise reduction effect of a low-height noise barrier system was predicted and evaluated for operating railway sites within the frame- work of a national research project in Korea. The comparison of calculated and measured values showed differences within 2.5 dB.

scholarly journals Soil Moisture Dynamics in Response to Precipitation and Thinning in a Semi-Dry Forest in Northern Mexico

Water ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 105
Author(s):  
Argelia E. Rascón-Ramos ◽  
Martín Martínez-Salvador ◽  
Gabriel Sosa-Pérez ◽  
Federico Villarreal-Guerrero ◽  
Alfredo Pinedo-Alvarez ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Forest Management ◽  
Water Availability ◽  
Dry Forest ◽  
Rainfall Events ◽  
Rainfall Characteristics ◽  
Northern Mexico ◽  
The Difference ◽  
The Impact ◽  
Moisture Dynamics

Understanding soil moisture behavior in semi-dry forests is essential for evaluating the impact of forest management on water availability. The objective of the study was to analyze soil moisture based in storm observations in three micro-catchments (0.19, 0.20, and 0.27 ha) with similar tree densities, and subject to different thinning intensities in a semi-dry forest in Chihuahua, Mexico. Vegetation, soil characteristics, precipitation, and volumetric water content were measured before thinning (2018), and after 0%, 40%, and 80% thinning for each micro-catchment (2019). Soil moisture was low and relatively similar among the three micro-catchments in 2018 (mean = 8.5%), and only large rainfall events (>30 mm) increased soil moisture significantly (29–52%). After thinning, soil moisture was higher and significantly different among the micro-catchments only during small rainfall events (<10 mm), while a difference was not noted during large events. The difference before–after during small rainfall events was not significant for the control (0% thinning); whereas 40% and 80% thinning increased soil moisture significantly by 40% and 53%, respectively. Knowledge of the response of soil moisture as a result of thinning and rainfall characteristics has important implications, especially for evaluating the impact of forest management on water availability.

scholarly journals 216. Are Automatic Antimicrobial Stop Orders an Effective Stewardship Tool for Urinary Tract and Intra-Abdominal Infections?

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S110-S110
Author(s):  
Christina Maguire ◽  
Dusten T Rose ◽  
Theresa Jaso
Keyword(s):  
Urinary Tract ◽  
Antimicrobial Therapy ◽  
Source Control ◽  
Clostridioides Difficile ◽  
Days Of Therapy ◽  
Before And After ◽  
The Difference ◽  
Tract Infections ◽  
Length Of Therapy ◽  
The Impact

Abstract Background Automatic antimicrobial stop orders (ASOs) are a stewardship initiative used to decrease days of therapy, prevent resistance, and reduce drug costs. Limited evidence outside of the perioperative setting exists on the effects of ASOs on broad spectrum antimicrobial use, discharge prescription duration, and effects of missed doses. This study aims to evaluate the impact of an ASO policy across a health system of adult academic and community hospitals for treatment of intra-abdominal (IAI) and urinary tract infections (UTI). ASO Outcome Definitions ASO Outcomes Methods This multicenter retrospective cohort study compared patients with IAI and UTI treated before and after implementation of an ASO. Patients over the age of 18 with a diagnosis of UTI or IAI and 48 hours of intravenous (IV) antimicrobial administration were included. Patients unable to achieve IAI source control within 48 hours or those with a concomitant infection were excluded. The primary outcome was the difference in sum length of antimicrobial therapy (LOT). Secondary endpoints include length and days of antimicrobial therapy (DOT) at multiple timepoints, all cause in hospital mortality and readmission, and adverse events such as rates of Clostridioides difficile infection. Outcomes were also evaluated by type of infection, hospital site, and presence of infectious diseases (ID) pharmacist on site. Results This study included 119 patients in the pre-ASO group and 121 patients in the post-ASO group. ASO shortened sum length of therapy (LOT) (12 days vs 11 days respectively; p=0.0364) and sum DOT (15 days vs 12 days respectively; p=0.022). This finding appears to be driven by a decrease in outpatient LOT (p=0.0017) and outpatient DOT (p=0.0034). Conversely, ASO extended empiric IV LOT (p=0.005). All other secondary outcomes were not significant. Ten patients missed doses of antimicrobials due to ASO. Subgroup analyses suggested that one hospital may have influenced outcomes and reduction in LOT was observed primarily in sites without an ID pharmacist on site (p=0.018). Conclusion While implementation of ASO decreases sum length of inpatient and outpatient therapy, it may not influence inpatient length of therapy alone. Moreover, ASOs prolong use of empiric intravenous therapy. Hospitals without an ID pharmacist may benefit most from ASO protocols. Disclosures All Authors: No reported disclosures

scholarly journals Evolution of disease transmission during the COVID-19 pandemic: patterns and determinants

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jie Zhu ◽  
Blanca Gallego
Keyword(s):  
Public Health ◽  
Disease Transmission ◽  
Clustering Algorithm ◽  
Health Interventions ◽  
Transmission Model ◽  
Model Parameters ◽  
Public Health Interventions ◽  
Forecasting Accuracy ◽  
Time Lagged ◽  
The Impact

AbstractEpidemic models are being used by governments to inform public health strategies to reduce the spread of SARS-CoV-2. They simulate potential scenarios by manipulating model parameters that control processes of disease transmission and recovery. However, the validity of these parameters is challenged by the uncertainty of the impact of public health interventions on disease transmission, and the forecasting accuracy of these models is rarely investigated during an outbreak. We fitted a stochastic transmission model on reported cases, recoveries and deaths associated with SARS-CoV-2 infection across 101 countries. The dynamics of disease transmission was represented in terms of the daily effective reproduction number ($$R_t$$ R t ). The relationship between public health interventions and $$R_t$$ R t was explored, firstly using a hierarchical clustering algorithm on initial $$R_t$$ R t patterns, and secondly computing the time-lagged cross correlation among the daily number of policies implemented, $$R_t$$ R t , and daily incidence counts in subsequent months. The impact of updating $$R_t$$ R t every time a prediction is made on the forecasting accuracy of the model was investigated. We identified 5 groups of countries with distinct transmission patterns during the first 6 months of the pandemic. Early adoption of social distancing measures and a shorter gap between interventions were associated with a reduction on the duration of outbreaks. The lagged correlation analysis revealed that increased policy volume was associated with lower future $$R_t$$ R t (75 days lag), while a lower $$R_t$$ R t was associated with lower future policy volume (102 days lag). Lastly, the outbreak prediction accuracy of the model using dynamically updated $$R_t$$ R t produced an average AUROC of 0.72 (0.708, 0.723) compared to 0.56 (0.555, 0.568) when $$R_t$$ R t was kept constant. Monitoring the evolution of $$R_t$$ R t during an epidemic is an important complementary piece of information to reported daily counts, recoveries and deaths, since it provides an early signal of the efficacy of containment measures. Using updated $$R_t$$ R t values produces significantly better predictions of future outbreaks. Our results found variation in the effect of early public health interventions on the evolution of $$R_t$$ R t over time and across countries, which could not be explained solely by the timing and number of the adopted interventions.

Arterial Stiffness Assessed by Cardio-Ankle Vascular Index in Patients With Abdominal Aortic Aneurysm and Its Alterations After Treatment

2021 ◽  
pp. 153857442110232
Author(s):  
Spyridon N. Mylonas ◽  
Konstantinos G. Moulakakis ◽  
Nikolaos Kadoglou ◽  
Constantinos Antonopoulos ◽  
Thomas E. Kotsis ◽  
...  
Keyword(s):  
Arterial Stiffness ◽  
Surgical Repair ◽  
Open Repair ◽  
Abdominal Aortic ◽  
Gender And Age ◽  
Baseline Values ◽  
The Difference ◽  
The Impact ◽  
Repair Group

Purpose: The aim of the present study was to investigate a potential difference on the arterial stiffness among aneurysm patients and non-aneurysm controls, as well as to explore potential changes between patients treated either with endovascular or open repair. Materials and Methods: A 110 patients with an infrarenal AAA were prospectively enrolled in this study. Fifty-six patients received an EVAR, whereas 54 patients received an open surgical repair. Moreover, 103 gender and age-matched subjects without AAA served as controls. The cardio-ankle vascular index (CAVI) was applied for measurement of the arterial stiffness. Results: CAVI values were statistically higher in the AAA patients when compared with control subjects. Although at 48 hours postoperatively the CAVI values were increased in both groups when compared to baseline values, the difference in CAVI had a tendency to be higher in the open group compared to the endovascular group. At 6 months of follow up the CAVI values returned to the baseline for the patients of the open repair group. However, in the endovascular group CAVI values remained higher when compared with the baseline values. Conclusion: Patients with AAAs demonstrated a higher value of CAVI compared to healthy controls. A significant increase of arterial stiffness in both groups during the immediate postoperative period was documented. The increase in arterial stiffness remained significant at 6 months in EVAR patients. Further studies are needed to elucidate the impact of a decreased aortic compliance after stentgraft implantation on the cardiac function of patients with AAA.

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