Widespread Source Research Articles

Simplified Approach for Preliminary Evaluation of Effective Dose Rates for Field Applications of D-T Neutron Generators

Portable neutron generators are one of the most widespread sources of fast neutrons for different applications, from activation analysis to quantitative estimation of fissile and fertile materials in radioactive waste packages. New techniques based on these devices have been developed for homeland security, e.g. neutron interrogations of packages suspected of containing substances such as explosives. When using portable generators determination of radiation protection quantities is affected by a series of boundary conditions that could differ from an experimental set-up to another, and Radiation Protection Experts cannot assess operator exposure without the aid of time-expensive Monte Carlo simulations. As it is impossible to foresee all kind of scenarios involving such applications, and time is often a critical variable, safety assessment requires faster, even if less accurate, tools for exposure evaluation. In this article experimental measurements of dose rates in a real scenario involving a D-T neutron generator are considered, to validate the Monte Carlo model developed. Consequently, it was possible to demonstrate that the calibration factor at 14 MeV for a neutron dosimeter provides conservative dose estimates and to propose a stand-alone, fast, and easy-to-use calculation tool which is usable on field by the Radiation Protection Expert without full Monte Carlo calculations.

Thermal limits in the face of infectious disease: How important are pathogens?

The frequency and severity of both extreme thermal events and disease outbreaks are predicted to continue to shift as a consequence of global change. As a result, species persistence will likely be increasingly dependent on the interaction between thermal stress and pathogen exposure. Missing from the intersection between studies of infectious disease and thermal ecology, however, is the capacity for pathogen exposure to directly disrupt a host's ability to cope with thermal stress. Common sources of variation in host thermal performance, which are likely to interact with infection, are also often unaccounted for when assessing either the vulnerability of species or the potential for disease spread during extreme thermal events. Here, we describe how infection can directly alter host thermal limits, to a degree that exceeds the level of variation commonly seen across species large geographic distributions and that equals the detrimental impact of other ecologically relevant stressors. We then discuss various sources of heterogeneity within and between populations that are likely to be important in mediating the impact that infection has on variation in host thermal limits. In doing so we highlight how infection is a widespread and important source of variation in host thermal performance, which will have implications for both the persistence and vulnerability of species and the dynamics and transmission of disease in a more thermally extreme world.

Lignin functionalization strategies and the potential applications of its derivatives – A Review

Lignin is one of the most important and widespread carbon sources on Earth. Significant amounts of lignin are delivered to the market by pulp mills and biorefineries, and there have been many efforts to develop routes for its valorization. Over the years, lignin has been used to produce biobased chemicals, materials, and advanced biofuels on the basis of its variable functionalities and physicochemical properties. Today, lignin’s applications are still limited by its heterogeneity, variability, and low reactivity. Thus, modification technologies have been developed to allow lignin to be suitable for a wider range of attractive industrial applications. The most common modifications used for this purpose include amination, methylation, demethylation, phenolation, sulfomethylation, oxyalkylation, acylation or esterification, epoxidation, phosphorylation, nitration, and sulfonation. This article reviews the chemistry involved in these lignin modification technologies, discussing their effect on the finished product while presenting some market perspectives and future outlook to utilize lignin in sustainable biorefineries.

Ultrastable Tb-Organic Framework as a Selective Sensor of Phenylglyoxylic Acid in Urine.

Industrial pollution and harmful chemicals seriously affect environment and human health. Styrene is a common air toxicant with widespread exposure sources, including smoking, automobile exhaust, and plastic pollutants. Phenylglyoxylic acid (PGA) is a typical biomarker for exposed styrene. Therefore, it is crucial to quickly identify and quantitatively detect PGA. Herein, an ultrastable terbium metal-organic framework (Tb-MOF 1) was developed, and the luminescence film (1/PLA) consisting of polylactic acid (PLA) and 1 was fabricated as a sensor for rapid detection of PGA. The sensor possesses the advantages of efficient detection [limit of detection (LOD) is 1.05 × 10-4 mg/mL] and rapid response speed (less than 10 s) for PGA in urine. Furthermore, this sensor exhibits high stability, outstanding anti-interference ability, and excellent recyclability. Based on this film technology, a paper-based probe was then developed for portable and convenient detection. The probe could easily distinguish different concentrations of PGA under the naked eye toward practical sensing applications. Meanwhile, photoinduced electron transfer was demonstrated to be responsible for the luminescence sensing. Hence, this study indicates that Tb-MOF is a promising material to detect PGA for evaluating the effect of styrene on the body.

Development of current ambient background threshold values for sediment quality parameters in U.S. lakes on a regional and statewide basis

For the first time, background threshold values have been developed for a large suite of sediment quality parameters from 969 lakes spanning the conterminous United States (U.S.). These values provide a statistical basis for estimating current ambient background, which refers to chemical and physical (e.g., grain size) concentrations derived from natural and/or widespread diffuse anthropogenic sources (e.g., nonpoint sources like atmospheric deposition and land runoff). Surficial sediment quality data, collected based on the randomized, probability-based sampling design of the 2017 National Lakes Assessment (NLA) study, were utilized for this effort. These data included 16 metal(loid)s, 25 polycyclic aromatic hydrocarbons (PAHs), 53 polychlorinated biphenyl (PCB) congeners, 27 legacy organochlorine pesticides and metabolites, total organic carbon (TOC), and grain size parameters. The data were analyzed based on different geographic areas, including: 10 U.S. Environmental Protection Agency (EPA) Regions, two major ecoregions bisecting the State of Minnesota (i.e., Temperate Plains and Upper Midwest), and for Minnesota. Hypothesis testing of 47 sediment quality parameters was performed on three geographic areas bisecting Minnesota, and there were many statistically significant (p < 0.05) differences between geographic pairs that included Minnesota. Background threshold values were calculated for parameters with >20% detects using 95% one-sided upper tolerance limit (UTL) with 95% coverage (UTL95-95) values. The UTL95-95 represents the value below which 95% of the population values are expected to fall with 95% confidence. These values were compared to matching sediment quality guidelines for the protection of benthic organisms, both with and without potential outliers removed. Applications and limitations of the UTL95-95 values are discussed. Jurisdictions within the continental U.S. could use these same publicly available sediment quality data to calculate UTL95-95 values for specific geographic areas, and other countries could design similar probabilistic field studies to determine current ambient background of sediment quality parameters in lake sediments.

Two decades of contagion effect on stock markets: Which events are more contagious?

This study aims to investigate the impact of a wide range of economic and non-economic events on stock market spillover effects in a group of 16 major developed and emerging countries over the 2000–2020 period. We analyse the size and structure of contagion to verify how different events spread contagion across borders and sectors. We applied the methodology proposed by Diebold and Yilmaz (2009, 2012, 2014) to a wide range of stock market indices using a quantile regression framework. Our findings show that the sectoral and country-specific indices usually range below the overall market contagion levels, while their density functions differ structurally from those of overall market contagion. Among non-economic events, viruses – notably, the COVID-19 pandemic – are the most widespread sources of contagion, while terrorism events affect the widest range of sectors with the greatest magnitude. Among economic events, the strongest negative impact is found for prudential ones. Quantitative easing (QE) and liquidity support reduce overall market contagion, while QE unwinding has a more substantial role than its introduction or expansion, exemplifying its asymmetric impact. We also investigate how investors may benefit from using contagion information in developing trading strategies, highlighting the positive impact of spillover-based weightings on portfolio returns.

Fog - low stratus (FLS) regimes on Corsica with wind and PBLH as key drivers

The French Mediterranean island of Corsica is already today confronted with a clear tendency towards water shortage, leading not only to socio-economical, but also to ecological problems. A potential, but not very widespread source of water is the presence of near-ground clouds, mostly fog. In this study, we investigate fog-low stratus (FLS) frequencies in Corsica, derived from a data set of Meteosat Second Generation SEVIRI, whereby a distinction between fog and low stratus is hardly feasible using remote sensing data. The FLS frequency was studied with respect to its interaction with distinct locally-generated wind and its dependence on the planetary boundary layer height (PBLH) obtained by ERA5 reanalysis (the fifth generation of the European Centre for Medium-Range Weather Forecasts, ECMWF). Results show that radiation FLS is formed in coastal areas at sunrise, with low PBLH. On the other hand, in the interior of the island at sunset, a maximum of advection FLS is formed, fostered by locally-generated and related transport of moisture. On the east side of the island, FLS frequency is lower throughout the year due to frequent lee situations. This situation is reinforced by reduced synoptic moisture transport by westerly winds, so that westerly exposed slopes benefit from moisture input by FLS formation.

Spectral correlations in a fiber-optical parametric oscillator

Tailoring wavelength correlations in fiber-optical sources through nonlinear phenomena could drive many quantum optics applications. However, to date, such correlations have not been explored within fiber-optical parametric oscillators (FOPO), which are now widespread wavelength-agile sources. We experimentally investigate the real-time dynamics of a synchronously pumped picosecond FOPO with a combination of statistical tools using time-stretch spectroscopy. The study of wavelength correlations allows us to unveil particular spectrotemporal dynamics and correlation patterns. Specifically, we demonstrate that combining mutual information (MI) analysis and least-squares regression with large ensembles of shot-to-shot spectra allows to efficiently track energy transfers from pump to parametric waves. In addition, we show that tuning the FOPO parameters enables the shaping of spectral correlations to a certain extent.

Hydro-power production capacity prediction based on machine learning regression techniques

Hydro-power is a widespread source of energy, which currently provides over 60% of total renewable electricity production. As such, it plays a key role in green power generation, and has a fundamental influence on power market prices, because it can be used as a buffer for more volatile renewable sources, and it is relatively cheap to ramp up and down. For these reasons, it is of paramount importance to accurately predict the monthly hydro-power production capacity of wide geographical zones of the electricity market. In fact, future hydro-power production capacity depends on meteorological and climatic processes, water storage as result of pumping activity in the plant, and, of course, actual production, and this makes it extremely difficult to obtain an accurate prediction using traditional techniques, such as auto-regressive models. In this paper we propose a methodology based on machine learning (ML) regression techniques, mainly artificial neural networks and support vector machines, and feature reduction mechanisms, such as principal component analysis and feature grouping techniques. We apply these techniques to model the relationship between the meteorological and climatic variables and the total water in the reservoir used for the hydro-power generation. We show how ML regression techniques are able to obtain an accurate prediction of the hydro-power capacity in a real life example in Northern Italy.

Natural gas geology and exploration direction of the Cambrian Lower Canglangpu Member in central Sichuan paleo-uplift, Sichuan Basin, SW China

Based on drilling data of JT1 and CS1, outcrop profiles and seismic data, the sedimentary pattern, space configuration of source-reservoir-cap combinations and paleouplift evolution characteristics of the Cambrian Lower Canglangpu Member in the central Sichuan paleouplift have been investigated to determine the favorable exploration zones. Controlled by Deyang-Anyue rift, the Lower Canglangpu Member features differential characteristics from east to west in sedimentary framework. In the west side of the Deyang-Anyue rift, this member is composed of clastic sediments, while in the east side of the Deyang-Anyue rift, it is fresh water shelf sediments, with grain beaches occurring along edges of the depressions, shelf and lagoon. Among the beaches, the dolomitic ones are mainly distributed around the depression edge and in the north of the lagoon. The beach sediments could become high quality reservoirs under the effect of karstification. Underlying the Lower Canglangpu Member is the widespread source rock of the Qiongzhusi Formation, so oil and gas generated by the Qiongzhusi Formation source rock can directly charge into the beach reservoirs. The sandy mudstone of the Upper Canglangpu Member can serve as the caprock of the Lower Canglangpu Member reservoir. The dolomitic beaches are located at the higher part of the paleo-uplift during the main accumulation period, with good hydrocarbon accumulation elements. Blocks PT1-CS1, HT1-GT2 and east GT2 are favorable exploration zones.

Enrichment of tight oil and its controlling factors in central and western China

Taking the tight oil of the Zhongnan sag in the Ordos Basin, Jimusar sag in the Junggar Basin and Qingxi sag in the Jiuquan Basin as study objects, based on field survey, dissection of tight oil reservoirs, sample test, modeling experiment and comprehensive analysis, this study reveals that the tight oil accumulates at start-up pressure, advances under differential pressure, diffuses at alternating fast and low speeds, charges in stepped large area and migrates rapidly through fractures, and enriches in dominant fractures and pores. The root cause of ladder-like charge is the multiple scales of pores. The widespread source rock with high hydrocarbon generation intensity is the material basis for tight oil enrichment; the dominant source reservoir assemblage is the basic unit for tight oil enrichment; fractures and beddings are conducive to local rapid migration of tight oil; fractures and pores work together to control the enrichment of tight oil. Two typical accumulation models of tight oil are established, namely “source reservoir in coexistence, four optimal factors controlling enrichment around central area, and large-scale continuous distribution” for a large freshwater lake clastic rock basin and “source reservoir integration, four optimal factors controlling enrichment, central area distribution, small in size but high in enrichment degree “ for a small saline lake diamictite depression.

Machine learning for anomaly detection in cyanobacterial fluorescence signals

Many drinking water utilities drawing from waters susceptible to harmful algal blooms (HABs) are implementing monitoring tools that can alert them to the onset of blooms. Some have invested in fluorescence-based online monitoring probes to measure phycocyanin, a pigment found in cyanobacteria, but it is not clear how to best use the data generated. Previous studies have focused on correlating phycocyanin fluorescence and cyanobacteria cell counts. However, not all utilities collect cell count data, making this method impossible to apply in some cases. Instead, this paper proposes a novel approach to determine when a utility needs to respond to a HAB based on machine learning by identifying anomalies in phycocyanin fluorescence data without the need for corresponding cell counts or biovolume. Four widespread and open source algorithms are evaluated on data collected at four buoys in Lake Erie from 2014 to 2019: local outlier factor (LOF), One-Class Support Vector Machine (SVM), elliptic envelope, and Isolation Forest (iForest). When trained on standardized historical data from 2014 to 2018 and tested on labelled 2019 data collected at each buoy, the One-Class SVM and elliptic envelope models both achieve a maximum average F1 score of 0.86 among the four datasets. Therefore, One-Class SVM and elliptic envelope are promising algorithms for detecting potential HABs using fluorescence data only.

Fluorinated containers may spread PFAS

Specially treated plastic containers could be widespread sources of toxic per- and polyfluoroalkyl substances (PFAS) in the environment, the US Environmental Protection Agency says. The EPA is aski...

The Influence of Fuel and Steam Consumption on Characteristics of Fixed Bed Process of Woody Biomass Steam Gasification with Intensive Heat Supply

Plant biomass is one of the most widespread renewable energy sources. Energy utilization of biomass allows solving some problems associated with the development of off-grid energy systems and the processing of combustible waste (primarily agricultural and forestry waste). This paper is devoted to the study of an allothermal gasification process of plant biomass materials using a kinetic-thermodynamic model developed by the author. The gasification process is considered stationary, and steam is used as a gasification agent. The power of the supplied heat is considered constant (10 kW). One of the significant tasks related to allothermal gasification is to choose flowrate parameters so that the heat supplied is efficiently used in chemical reactions without the threat of reactor overheating. The determination of the boundaries of the safe gasifier operation involved variant calculations with a view to optimizing the gasification conditions. The calculation results show that the allothermal gasification process can proceed with a thermochemical efficiency of about 70%. For each fixed fuel consumption level, there is an optimal fuel-steam ratio. The complete conversion of biomass requires sufficiently high temperatures. The produced gas contains a significant steam fraction (&gt;50 vol%) even under optimal conditions. The calculated fraction of hydrogen in dry gas is up to 60vol%. The data obtained can be used to assess the efficiency of energy units with biomass gasification using high-temperature sources, for example, in systems that use and store solar thermal energy.

Impact of Renewable Energy Sources into Multi Area Multi-Source Load Frequency Control of Interrelated Power System

There is an increasing concentration in the influences of nonconventional power sources on power system process and management, as the application of these sources upsurges worldwide. Renewable energy technologies are one of the best technologies for generating electrical power with zero fuel cost, a clean environment, and are available almost throughout the year. Some of the widespread renewable energy sources are tidal energy, geothermal energy, wind energy, and solar energy. Among many renewable energy sources, wind and solar energy sources are more popular because they are easy to install and operate. Due to their high flexibility, wind and solar power generation units are easily integrated with conventional power generation systems. Traditional generating units primarily use synchronous generators that enable them to ensure the process during significant transient errors. If massive wind generation is faltered due to error, it may harm the power system’s operation and lead to the load frequency control issue. This work proposes binary moth flame optimizer (MFO) variants to mitigate the frequency constraint issue. Two different binary variants are implemented for improving the performance of MFO for discrete optimization problems. The proposed model was evaluated and compared with existing algorithms in terms of standard testing benchmarks and showed improved results in terms of average and standard deviation.

Maturity Assessment of the Lower Cambrian and Sinian Shales Using Multiple Technical Approaches

The Lower Cambrian Niutitang and Sinian Doushantuo shales are the most important and widespread source rocks and target layers in South China. Reliable data of the thermal maturity of organic matter (OM) is widely used to assess hydrocarbon generation and is a key property used in determining the viability and hydrocarbon potential of these new shales. Nevertheless, traditional thermal maturity indicators are no longer suited to the vitrinite-lack marine shales. This study aims to combine high throughput Raman and infrared spectroscopy analysis to confirm and validate the thermal maturity in comparison with the bitumen reflectance (Rb). Raman parameters such as the differences between the positions of the two bands (VG-VD) are strong parameters for calculating the thermal maturity in a large vitrinite reflectance (Ro) ranging from 1.60% to 3.80%. The infrared spectroscopy analysis indicates that the aromatic C=C bands and CH2/CH3 aliphatic groups both are closely correlated with thermal maturity. The calculated Ro results from Raman and infrared spectroscopy are in strong coincidence with the Rb. The relationships between Rb and pore volumes/surface areas (calculated from N2 adsorption) indicate that the sample with Rb of 3.40% has the lowest pore volumes and surface areas. Focused ion beam scanning electron microscopy (FIB-SEM) observations of OM pores indicate that Ro of approximately 3.60% may be an upper limit for OM porosity development. Obviously, kerogen Raman and infrared spectroscopy can indicate methods for reducing the risk in assessing maturity with practical, low-cost accurate results. Exploration of shale gas in the high maturity (>3.40%–3.60%) region carries huge risks.

Application of Remote Sensing Technique to Examine the Oil Pollution of the Shatt Al-Arab Water

ABSTRACT In this study the water is a natural resource that cannot be dispensed with in all areas of life. Water pollution has a direct impact on community life, as water is a necessary requirement for humans and other living organisms. Water in its natural sources is exposed to many types of pollution, including what is natural, which shows a change in the temperature of the water or an increase in its salinity, and some of which are chemical, such as pollution with sewage water, oil leakage and others. Oil and its derivatives are the most widespread and influential sources of water pollution. Oil pollutants are considered the most dangerous pollutants of coasts, seas and oceans, through what oil tankers cause in the leakage of about two million tons annually of crude oil into the seas and oceans. Oil pollution of the water has spread in recent years, especially in the Shatt al-Arab in Basra Governorate, which has dire effects on the human environment and health, as the incidents of oil spills into lead to a great shortage in the Quantity and quality of marine food sources, on top the fish wealth. The arrival of oil spills to the beaches harms tourism by distorting the environment, so measures and treatments have to be taken, standards set, and legislation enacted to reduce this type of pollution because of the seriousness of its effects on various forms of life on earth.Oil leakage is a complex problem.

The Dietary Importance of Kelp-Derived Detritus to Pelagic and Benthic Consumers along the West Coast of Vancouver Island, Canada

Stable isotope analysis was used to determine the relative dietary importance of kelp-derived detritus to plankton and benthic organisms along a gradient of kelp abundance driven by recovering sea otter populations along the west coast of Vancouver Island (WCVI), Canada. The study used region-specific kelp isotope values (δ13C and δ15N) and season-specific phytoplankton isotope values to model dietary contributions of kelp-derived detritus (KDD). In general, KDD contributions were moderate to high in most plankton size fractions during the summer and decreased during the winter, particularly in the kelp sparse region. Hypothesized regional and spatial (distance from the coast) differences in kelp detritus contributions to zooplankton were not evident. Modeled estimates of the KDD contribution to benthic invertebrates were high (>40%) and independent of the organism size, among regions and between seasons, with the exception of Astraea gibberosa in the kelp abundant region. Local oceanography, natural kelp isotope signature variation, and significant overlap between kelps’ and blooming phytoplankton isotope values led to a large uncertainty in the assessed KDD contributions in benthic organisms. These results highlighted the importance of the KDD as a widespread and stable year-round food source in coastal kelp populated regions.

Minimizing the environmental impact of PFAS by using specialized coagulants for the treatment of PFAS polluted waters and for the decontamination of firefighting equipment

Per- and polyfluoroalkyl substances (PFASs) represent an increasingly global challenge for keeping water and soil “non-toxic”. 100 of millions of people are exposed to PFAS levels of concern, in particular, around PFAS production sites and sites where PFASs are/were used and released or disposed. The Stockholm Convention established recommendations to systematically assess PFOS pollution which can be transposed to all PFASs considering that PFASs are an issue of concern under The Strategic Approach to International Chemical Management (SAICM). One major wide-spread source of environmental pollution is the long-term use of PFAS-containing fire extinguishing agents. Strategies for the reduction of human exposure need to reduce and were feasible eliminate the current uses of PFASs and reduce and eliminate the human exposure from the contamination of the environment from past uses including contaminated drinking water.The current study shows that well-known methods of water treatment, especially the use of materials for adsorption and ion exchange, can often neither guarantee satisfactory cleaning results nor economically justifiable filter running times at high PFAS concentrations and complex matrix conditions. Their combination with a pre-precipitation stage using specialized precipitants can significantly optimize treatment successes.PFAS is still being released into the environment in considerable quantities by e.g. the use of so-called aqueous film forming foams (AFFF). Fire departments are increasingly trying to reduce the risks associated with the use of AFFF agents for the health of firefighting personnel and the environment by replacing AFFF foaming agents with fluorine-free foaming agents. If the fluorine-containing foaming agents are simply replaced, considerable residual PFAS loads often remain in the fire extinguishing systems contaminated with PFAS (fire engines, fire boats, stationary fire extinguishing systems, etc.), which are then discharged further into the environment during renewed operations - normally at a reduced concentration. The current study demonstrate that a conscientious decontamination of systems previously in contact with PFAS is therefore urgently required. Here, too, precipitants specialized for PFAS adsorption can make an important contribution to protecting the environment. Sites were firefighting equipment has been cleaned over years can also be considered contaminated and need assessment and possibly remediation.

Investigation of the environmental characteristics of a diesel engine when operating on activated fuel

The internal combustion engine is the most widespread source of energy for vehicles. The main requirements for an internal combustion engine include: the efficiency of functioning as part of a vehicle, high performance indicators, as well as environmental parameters of the emission of exhaust gases into the environment. The fulfillment of these conditions is possible by improving the design of the engine, as well as improving the working process of the diesel engine while increasing the quality of diesel fuel or additional impact directly on the fuel itself. One of the most effective ways to influence diesel fuel is to transfer a certain amount of heat to it in the high-pressure fuel line in front of the injectors. At the same time, the physical and mechanical properties of diesel fuel change, which leads to a change in mixture formation and the combustion process in the engine cylinder. To intensify the combustion process, a method of preliminary high-temperature local heating of diesel fuel in the fuel supply system in front of the injectors was proposed. To achieve this goal, several main directions were identified, including the study of environmental indicators during the intensification of the combustion process. The tests were carried out in stages. At the first stage, the operation of the fuel injector when operating on activated fuel (bench, laboratory tests) was investigated. At the next stage, the indicators of the diesel engine in the main modes of its operation were investigated. Bench (laboratory) tests made it possible to draw a conclusion about the operability and compliance of the aggregate with the technical requirements of the manufacturer and the parameters of GOST. The bench tests proved the possibility of a diesel engine running on activated fuel without deteriorating environmental performance in the exhaust gases; at the same time, changes in the toxicity and smoke of the exhaust gases from different values of the average effective pressure were revealed.