A Study of Organo-phosphorous Simulants Thermal Destruction Using Shock Tube/Laser Diagnostics Techniques and Chemical Kinetics Modeling

High-fidelity chemical kinetic models are critical in predictive modeling during design and optimization of next generation energy systems. Shock tube provides an ideal tool to investigate high-temperature chemical kinetics. Non-intrusive laser absorption diagnostics provide in-situ measurements of quantitative, time-resolved species concentration data in this complex chemically reacting system. In this work, shock tube and laser absorption spectroscopy were utilized to measure species concentration time-histories during pyrolysis and oxidation of organo-phosphorous compounds (OPCs). The experiments data obtained were used as benchmark to develop an improved kinetic model of OPCs combustion. Interest in combustion chemistry of OPCs is associated to their use as fire suppressants and as chemical weapons. Pyrolysis and oxidation of OPCs were carried out behind reflected shock wave and laser absorption spectroscopy utilizing quantum cascade laser at mid-IR wavelength region was used to measure time resolved intermediate CO concentration produced during the process. Utilizing the experiments data, an improved chemical kinetic model for combustion of an OPC – Triethyl Phosphate (TEP) was developed. Various steps taken to develop the improved model include: calculation of thermochemical properties; updating hydrocarbon kinetics; calculation of reaction rates and addition of alternative TEP decomposition pathways. The prediction of TEP combustion, in terms intermediate CO concentration yield during its pyrolysis and oxidation, made by the improved model is in much better agreement with the experiments. Such an accurate kinetic model is critical in predicting the effectiveness of OPCs as flame retardants when used as dopants in hydrocarbon fuels; and in devising counter weapon of mass destruction strategies to destroy chemical weapons

The global burden of cancer attributable to risk factors, 2010-19 : a systematic analysis for the Global Burden of Disease Study 2019

Background Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. We analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally. Methods The GBD 2019 comparative risk assessment framework was used to estimate cancer burden attributable to behavioural, environmental and occupational, and metabolic risk factors. A total of 82 risk-outcome pairs were included on the basis of the World Cancer Research Fund criteria. Estimated cancer deaths and disability-adjusted life-years (DALYs) in 2019 and change in these measures between 2010 and 2019 are presented. Findings Globally, in 2019, the risk factors included in this analysis accounted for 4.45 million (95% uncertainty interval 4.01-4.94) deaths and 105 million (95.0-116) DALYs for both sexes combined, representing 44.4% (41.3-48.4) of all cancer deaths and 42.0% (39.1-45.6) of all DALYs. There were 2.88 million (2.60-3.18) risk-attributable cancer deaths in males (50.6% [47.8-54.1] of all male cancer deaths) and 1.58 million (1.36-1.84) risk-attributable cancer deaths in females (36.3% [32.5-41.3] of all female cancer deaths). The leading risk factors at the most detailed level globally for risk-attributable cancer deaths and DALYs in 2019 for both sexes combined were smoking, followed by alcohol use and high BMI. Risk-attributable cancer burden varied by world region and Socio-demographic Index (SDI), with smoking, unsafe sex, and alcohol use being the three leading risk factors for risk-attributable cancer DALYs in low SDI locations in 2019, whereas DALYs in high SDI locations mirrored the top three global risk factor rankings. From 2010 to 2019, global risk-attributable cancer deaths increased by 20.4% (12.6-28.4) and DALYs by 16.8% (8.8-25.0), with the greatest percentage increase in metabolic risks (34.7% [27.9-42.8] and 33.3% [25.8-42.0]). Interpretation The leading risk factors contributing to global cancer burden in 2019 were behavioural, whereas metabolic risk factors saw the largest increases between 2010 and 2019. Reducing exposure to these modifiable risk factors would decrease cancer mortality and DALY rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden. Copyright (C) 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.Peer reviewe

Global burden and strength of evidence for 88 risk factors in 204 countries and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

Background: Understanding the health consequences associated with exposure to risk factors is necessary to inform public health policy and practice. To systematically quantify the contributions of risk factor exposures to specific health outcomes, the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 aims to provide comprehensive estimates of exposure levels, relative health risks, and attributable burden of disease for 88 risk factors in 204 countries and territories and 811 subnational locations, from 1990 to 2021. Methods: The GBD 2021 risk factor analysis used data from 54 561 total distinct sources to produce epidemiological estimates for 88 risk factors and their associated health outcomes for a total of 631 risk–outcome pairs. Pairs were included on the basis of data-driven determination of a risk–outcome association. Age-sex-location-year-specific estimates were generated at global, regional, and national levels. Our approach followed the comparative risk assessment framework predicated on a causal web of hierarchically organised, potentially combinative, modifiable risks. Relative risks (RRs) of a given outcome occurring as a function of risk factor exposure were estimated separately for each risk–outcome pair, and summary exposure values (SEVs), representing risk-weighted exposure prevalence, and theoretical minimum risk exposure levels (TMRELs) were estimated for each risk factor. These estimates were used to calculate the population attributable fraction (PAF; ie, the proportional change in health risk that would occur if exposure to a risk factor were reduced to the TMREL). The product of PAFs and disease burden associated with a given outcome, measured in disability-adjusted life-years (DALYs), yielded measures of attributable burden (ie, the proportion of total disease burden attributable to a particular risk factor or combination of risk factors). Adjustments for mediation were applied to account for relationships involving risk factors that act indirectly on outcomes via intermediate risks. Attributable burden estimates were stratified by Socio-demographic Index (SDI) quintile and presented as counts, age-standardised rates, and rankings. To complement estimates of RR and attributable burden, newly developed burden of proof risk function (BPRF) methods were applied to yield supplementary, conservative interpretations of risk–outcome associations based on the consistency of underlying evidence, accounting for unexplained heterogeneity between input data from different studies. Estimates reported represent the mean value across 500 draws from the estimate's distribution, with 95% uncertainty intervals (UIs) calculated as the 2·5th and 97·5th percentile values across the draws. Findings: Among the specific risk factors analysed for this study, particulate matter air pollution was the leading contributor to the global disease burden in 2021, contributing 8·0% (95% UI 6·7–9·4) of total DALYs, followed by high systolic blood pressure (SBP; 7·8% [6·4–9·2]), smoking (5·7% [4·7–6·8]), low birthweight and short gestation (5·6% [4·8–6·3]), and high fasting plasma glucose (FPG; 5·4% [4·8–6·0]). For younger demographics (ie, those aged 0–4 years and 5–14 years), risks such as low birthweight and short gestation and unsafe water, sanitation, and handwashing (WaSH) were among the leading risk factors, while for older age groups, metabolic risks such as high SBP, high body-mass index (BMI), high FPG, and high LDL cholesterol had a greater impact. From 2000 to 2021, there was an observable shift in global health challenges, marked by a decline in the number of all-age DALYs broadly attributable to behavioural risks (decrease of 20·7% [13·9–27·7]) and environmental and occupational risks (decrease of 22·0% [15·5–28·8]), coupled with a 49·4% (42·3–56·9) increase in DALYs attributable to metabolic risks, all reflecting ageing populations and changing lifestyles on a global scale. Age-standardised global DALY rates attributable to high BMI and high FPG rose considerably (15·7% [9·9–21·7] for high BMI and 7·9% [3·3–12·9] for high FPG) over this period, with exposure to these risks increasing annually at rates of 1·8% (1·6–1·9) for high BMI and 1·3% (1·1–1·5) for high FPG. By contrast, the global risk-attributable burden and exposure to many other risk factors declined, notably for risks such as child growth failure and unsafe water source, with age-standardised attributable DALYs decreasing by 71·5% (64·4–78·8) for child growth failure and 66·3% (60·2–72·0) for unsafe water source. We separated risk factors into three groups according to trajectory over time: those with a decreasing attributable burden, due largely to declining risk exposure (eg, diet high in trans-fat and household air pollution) but also to proportionally smaller child and youth populations (eg, child and maternal malnutrition); those for which the burden increased moderately in spite of declining risk exposure, due largely to population ageing (eg, smoking); and those for which the burden increased considerably due to both increasing risk exposure and population ageing (eg, ambient particulate matter air pollution, high BMI, high FPG, and high SBP). Interpretation: Substantial progress has been made in reducing the global disease burden attributable to a range of risk factors, particularly those related to maternal and child health, WaSH, and household air pollution. Maintaining efforts to minimise the impact of these risk factors, especially in low SDI locations, is necessary to sustain progress. Successes in moderating the smoking-related burden by reducing risk exposure highlight the need to advance policies that reduce exposure to other leading risk factors such as ambient particulate matter air pollution and high SBP. Troubling increases in high FPG, high BMI, and other risk factors related to obesity and metabolic syndrome indicate an urgent need to identify and implement interventions

Ftir Absorption Cross Section Measurements Of Organo Phosphorus Compounds

Due to extreme toxicity of chemical warfare (CW) agents, experiments to study their combustion behavior are carried out using simulants. Organo Phosphorus Compounds (OPC\u27s) are commonly used as CW simulants and are also considered as flame retardants. In this study, gas phase absorption cross section of a CW simulant - Tri-methyl Phosphate (TMP) has been measured at 2 cm-1 resolution, and within 750-3500 cm-1 wavenumber range (2.85-13.33µm). The measurement was carried out at 295 K using in-house built FTIR sample cell with Ge-windows. Due to low vapor pressure of these compounds, a novel experimental technique has been developed in which liquid sample was taken in a boat and placed inside the sample cell. Current measurement were taken when the concentration of TMP inside the sample cell reached a stable value, i.e. the saturation vapor pressure at ambient condition. This quantitative gas-phase spectra is very important in setting up laser based monitoring schemes in combustion reactors

Mhz-Rate Measurements Of Time-Resolved Species Concentrations In Shock Heated Chemical Weapon Simulants

In this study, shock-heated decomposition kinetics study of triethyl phosphate (TEP), a simulant of chemical weapon Sarin-GB, was carried out in a shock tube. Mid-infrared, time-resolved laser absorption spectroscopy was used to measure the concentrations of CO, a key intermediate species, behind reflected shock waves

High Pressure Ignition Delay Times Measurements And Comparison Of The Performance Of Several Oxy-Syngas Mechanisms Under High Co2 Dilution

In this study, syngas combustion was investigated behind reflected shock waves in CO2 bath gas to measure ignition delay times and to probe the effects of CO2 dilution. New syngas data were taken between pressures of 34.58-45.50 atm and temperatures of 1113-1275K. This study provides experimental data for syngas combustion in CO2 diluted environments: ignition studies in a shock tube (59 data points in 10 datasets). In total, these mixtures covered a range of temperatures T, pressures P, equivalence ratios φ, H2/CO ratio θ, and CO2 diluent concentrations. Multiple syngas combustion mechanisms exist in the literature for modelling ignition delay times and their performance can be assessed against data collected here. In total, twelve mechanisms were tested and presented in this work. All mechanisms need improvements at higher pressures for accurately predicting the measured ignition delay times. At lower pressures, some of the models agreed relatively well with the data. Some mechanisms predicted ignition delay times which were 2 orders of magnitudes different from the measurements. This suggests there is behavior that has not been fully understood on the kinetic models and are inaccurate in predicting CO2 diluted environments for syngas combustion. To the best of our knowledge, current data are the first syngas ignition delay times measurements close to 50 atm under highly CO2 diluted (85% per vol.) conditions

A Study Of Methane And Hydrogen Ignition Delay Times In Co2 At High Pressures Near 40 Atm

Supercritical CO2 power generation cycles are being developed for cleaner and high efficiency combustion. For these systems to be designed, the chemical kinetics of combustion must be well understood at their operating regimes which are typically very high-pressure conditions. In this study, experiments were performed behind reflected shockwaves to measure the ignition delay times for methane and hydrogen in CO2 diluted environments at around 40 atmospheres. The temperature ranges were between 1325K to 1600 K for methane and 1150K to 1330K for hydrogen, respectively. Based on the data, Aramco 2.0 mechanism and GRI 3.0 mechanism are approximately modelling the ignition delay times of methane combustion, however, are unable to predict the ignition delay times of hydrogen

Shock Tube And Kinetic Modelling Study Of Organo Phosphorus Compounds Used As Chemical Weapon Simulants

Incineration is an effective way of destruction of chemical warfare agent. Increased threat of chemical warfare stockpile has renewed interest in their combustion chemistry. However, due to high toxicity of chemical warfare agents, experiments to study their combustion chemistry are carried out using organo phosphorous simulants. In this study kinetics study of oxidation of tri-ethyl phosphate (TEP) was carried out in a shock tube. Laser absorption spectroscopy was used to measured intermediate species (carbon monoxide) time histories. TEP is a simulant of Sarin-GB, a very toxic nerve agent which is used as a weapon of mass destruction. The intermediate CO time history data during TEP oxidation reported in this study will be useful in validation of kinetic models of organo phosphorous compounds and chemical warfare agents such as Sarin-GB

Sarin Simulant Combustion At High Temperature: Time Resolved Laser Absorption Spectroscopy Of Intermediate Products In A Shock Tube

Due to high toxicity of chemical warfare (CW) agents such as sarin - GB, experiments to study their incineration are carried out using organo phosphorous simulants. The simulants have similar chemical structures and combustion rates as that of CW agents, and knowledge on their decomposition kinetics can be used to predict combustion of CW agents. There are major gaps in our knowledge of the high temperature decomposition pathways leading to final products and combustion chemistry of CW agents and simulants that are crucial to characterize their burning process, which will help to design better strategies to counter weapons of mass destruction. Hence, pyrolysis of an organo phosphorous simulant – tri-ethyl phosphate (TEP) were carried out using shock tube and laser absorption spectroscopy at 4580.4 nm to measure intermediate CO time histories