Stagnant Conditions Research Articles

Contrasting effects of emission control on air pollution in Central China during the 2019 Military World Games based on satellite and ground observations

To ensure a good air quality during the 7th Military World Games (MWG) held in the megacity, Wuhan of central China, an unprecedented substantial emission reduction has been conducted during October 13–27, 2019. Here we present an observational overview on the effects of emission control measures as well as their implications by integrated satellite observations and surface measurements. Compared with air quality before control, there is a remarkable overall decline (~15–30%) in PM10 and SO2 concentration in control period. By contrast, NOx and O3 remain at high levels under persistent stagnant weather conditions since vehicle emission is not restricted. Despite high NOx (~100 μg/m3) in ground measurements, satellite column NO2 exhibits a considerable decline (~30–50%) over Wuhan, indicating that the large reduction of industrial emission from elevated chimneys has limited effects on changes of NOx near surface. The NO3− and NH4+ in PM2.5 reach peak values at the beginning of emergency control period, and then decrease steadily with a rising temperature. Meanwhile, OC and EC in PM2.5 have a continuous accumulation process on the premise of enhanced emission control, which can be caused by vehicle emissions. Generally, the stringent emission reduction focusing on industrial sources obviously mitigates particle pollution in Wuhan. Considering complicated relationship between atmospheric pollutants and their precursors, synchronized emission reduction measures based on their accurate roles are necessary in improving air quality effectively.

Strategies to reduce PM2.5 and O3 together during late summer and early fall in San Joaquin Valley, California

PM2.5 and O3 controls are traditionally considered separately because PM2.5 is usually high in winter while O3 is generally high in summer. In this study, we explore the opportunity of controlling the two pollutants simultaneously through a better understanding of their intra-seasonal correlation and chemical-coupling behaviors under different meteorological conditions during the late summer and early fall (August–September) episodes in the San Joaquin Valley (SJV), California. A correlation analysis is first used to identify the temporal correlations between O3 and PM2.5 and their underlying physical and chemical drivers. Sensitivity analysis is then applied to determine the chemical coupling between PM2.5 and O3 and subsequent multipollutant control opportunities under two contrasting meteorological conditions using the Community Multi-Scale Air Quality (CMAQ) model. We find that O3 and PM2.5 are positively correlated on the daily timescale because both are sensitive to atmospheric stagnation. However, O3 and PM2.5 are negatively correlated on the hourly timescale determined by the negative correlation between hourly NO3− and O3, which is mainly due to the opposite effects of T and RH on the diurnal variations of NO3− and O3. Reducing NOx on average lead to O3 increase, but it can facilitate reducing O3 at higher O3 (>75 ppb) locations under the more stagnant conditions. NOx emission control could become beneficial for both O3 and PM2.5 when the NOx emissions in 2005 are further reduced by 15% under the more stagnant meteorological conditions and by 30% under the more ventilated meteorological conditions.

Black Carbon Emission Reduction Due to COVID-19 Lockdown in China.

During the Lunar New Year Holiday of 2020, China implemented an unprecedented lockdown to fight the COVID‐19 outbreak, which strongly affected the anthropogenic emissions. We utilized elemental carbon observations (equivalent to black carbon, BC) from 42 sites and performed inverse modeling to determine the impact of the lockdown on the weekly BC emissions and quantify the effect of the stagnant conditions on BC observations in densely populated eastern and northern China. BC emissions declined 70% (eastern China) and 48% (northern China) compared to the first half of January. In northern China, under the stagnant conditions of the first week of the lockdown, the observed BC concentrations rose unexpectedly (29%) even though the BC emissions fell. The emissions declined substantially thereafter until a week after the lockdown ended. On the contrary, in eastern China, BC emissions dropped sharply in the first week and recovered synchronously with the end of the lockdown.

Explicit modeling of isoprene chemical processing in polluted air masses in suburban areas of the Yangtze River Delta region: radical cycling and formation of ozone and formaldehyde

Abstract. In recent years, ozone pollution has become one of the most severe environmental problems in China. Evidence from observations have showed increased frequency of high O3 levels in suburban areas of the Yangtze River Delta (YRD) region. To better understand the formation mechanism of local O3 pollution and investigate the potential role of isoprene chemistry in the budgets of ROx (OH+HO2+RO2) radicals, synchronous observations of volatile organic compounds (VOCs), formaldehyde (HCHO), and meteorological parameters were conducted at a suburban site of the YRD region in 2018. Five episodes with elevated O3 concentrations under stagnant meteorological conditions were identified; an observation-based model (OBM) with the Master Chemical Mechanism was applied to analyze the photochemical processes during these high O3 episodes. The high levels of O3, nitrogen oxides (NOx), and VOCs facilitated strong production and recycling of ROx radicals with the photolysis of oxygenated VOCs (OVOCs) being the primary source. Our results suggest that local biogenic isoprene is important in suburban photochemical processes. Removing isoprene could drastically slow down the efficiency of ROx recycling and reduce the concentrations of ROx. In addition, the absence of isoprene chemistry could further lead to a decrease in the daily average concentrations of O3 and HCHO by 34 % and 36 %, respectively. Therefore, this study emphasizes the importance of isoprene chemistry in the suburban atmosphere, particularly with the participation of anthropogenic NOx. Moreover, our results provide insights into the radical chemistry that essentially drives the formation of secondary pollutants (e.g., O3 and HCHO) in suburban areas of the YRD region.

Fabrication and characterization of nano structured honeycomb absorbers and thermal analyses on solar air heating collector

Fabrication of nano structured absorber is mandatory for reaping the enhanced thermal performance of solar collectors. In this connection, the nano carbon and aluminium composite was coated on aluminium substrate, which was similar to the hexagon shaped honey comb, and the solar absorber was developed. It was characterized through X-ray Diffractometer (XRD), Fourier Transform Infrared (FTIR) spectrometer and UV–Visible spectrophotometer (UV). It was also thermally analyzed not only in outdoor conditions but also in stagnant conditions in solar air heating collector. The research results pertaining to characterization of solar absorber showed that the crystallite size was in nano ranges and the nano particles had face-centre cubic structure. The research results pertaining to characterization of solar absorber also showed that the nano composite had excellent absorption in UV and visible region. The research result related to thermal analysis in outdoor environment revealed that the enhancements of temperature on solar absorbers coated with carbon and aluminium nano composite in the mass ratio of 60:40, 70:30 and 80:20 were 23.5oC, 25.1oC and 24.4oC respectively. The research result related to thermal analysis in stagnation environment also revealed that the enhancements of temperature on glass cover, carbon and aluminium nano composite coated absorber and working fluid were 69.4oC, 110.6oC and 99.0oC respectively. On the basis of research outcomes, it could be concluded that nano carbon and aluminium composite coated solar absorber would be used for photo thermal applications due to their desirable optical and thermal properties. It could also be concluded that nano carbon and aluminium composite coated solar absorbers would be used in photo thermal appliances due to their positive impact on thermal performances.

Greenhouse gases (CO2 and CH4) at an urban background site in Athens, Greece: Levels, sources and impact of atmospheric circulation

Year-round carbon dioxide (CO2) and methane (CH4) concentration measurements, performed for the first time in the city of Athens, Greece from December 21, 2018 to December 31, 2019, are presented in this study and analyzed in relation to atmospheric circulation patterns at a local, regional and long-range transport scale. Clear diurnal and seasonal variations of both greenhouse gases were detected. The observed increased levels during night and early morning hours are attributed to traffic/heating emissions and leakages of residential natural gas for CO2 and CH4, respectively. Using CO2 and CH4 levels simultaneously measured at the regional background site at Finokalia (Greece), increments in their levels due to local and regional anthropogenic sources within the city were assessed. For CO2, maximum and minimum increments were clearly observed during winter and summer respectively, suggesting a greater impact of combustion of fossil fuel and especially of biomass on CO2 levels during winter. On the other hand, CH4 increments were similar in all seasons, suggesting that local sources of CH4 remain quite constant year-round. Through the implementation of the Conditional Probability Function (CPF), the emission sources of theses greenhouse gases have been localized to the northern and the eastern domains of the Athens basin. Stagnant atmospheric conditions were also associated with an increased likelihood of CO2 and CH4 episodes. Backward modeling simulations with FLEXPART and HYSPLIT models indicate an industrial zone and a petrochemical zone, situated to the north and to the west of Athens respectively, as possible CH4 regional sources as well as possible CO2 contributions from southern directions attributed to shipping emissions from the port of Piraeus. The present study provides knowledge needed for the determination of greenhouse gas emission mitigation strategies in Athens.

Impact of the COVID-19 Lockdown on Air Quality and Resulting Public Health Benefits in the Mexico City Metropolitan Area.

Meteorology and long-term trends in air pollutant concentrations may obscure the results from short-term policies implemented to improve air quality. This study presents changes in CO, NO2, O3, SO2, PM10, and PM2.5 based on their anomalies during the COVID-19 partial (Phase 2) and total (Phase 3) lockdowns in Mexico City (MCMA). To minimise the impact of the air pollutant long-term trends, pollutant anomalies were calculated using as baseline truncated Fourier series, fitted with data from 2016 to 2019, and then compared with those from the lockdown. Additionally, days with stagnant conditions and heavy rain were excluded to reduce the impact of extreme weather changes. Satellite observations for NO2 and CO were used to contrast the ground-based derived results. During the lockdown Phase 2, only NO2 exhibited significant decreases (p < 0.05) of between 10 and 23% due to reductions in motor vehicle emissions. By contrast, O3 increased (p < 0.05) between 16 and 40% at the same sites where NO2 decreased. During Phase 3, significant decreases (p < 0.05) were observed for NO2 (43%), PM10 (20%), and PM2.5 (32%) in response to the total lockdown. Although O3 concentrations were lower in Phase 3 than during Phase 2, those did not decrease (p < 0.05) from the baseline at any site despite the total lockdown. SO2 decreased only during Phase 3 in a near-road environment. Satellite observations confirmed that NO2 decreased and CO stabilised during the total lockdown. Air pollutant changes during the lockdown could be overestimated between 2 and 10-fold without accounting for the influences of meteorology and long-term trends in pollutant concentrations. Air quality improved significantly during the lockdown driven by reduced NO2 and PM2.5 emissions despite increases in O3, resulting in health benefits for the MCMA population. A health assessment conducted suggested that around 588 deaths related to air pollution exposure were averted during the lockdown. Our results show that to reduce O3 within the MCMA, policies must focus on reducing VOCs emissions from non-mobile sources. The measures implemented during the COVID-19 lockdowns provide valuable information to reduce air pollution through a range of abatement strategies for emissions other than from motor vehicles.

Temporally resolved sectoral and regional contributions to air pollution in Beijing: informing short-term emission controls

Abstract. We investigate the contributions of local and regional emission sources to air pollution in Beijing to inform the design of short-term emission control strategies for mitigating major pollution episodes. We use a well-evaluated version of the WRF-Chem model at 3 km horizontal resolution to determine the daily accumulation of pollution over Beijing from local and regional sources in October 2014 under a range of meteorological conditions. Considering feasible emission reductions across residential, transport, power, and industrial sectors, we find that 1 d controls on local emissions have an immediate effect on PM2.5 (particulate matter with diameter less than 2.5 µm) concentrations on the same day but can have lingering effects as much as 5 d later under stagnant conditions. One-day controls in surrounding provinces have the greatest effect in Beijing on the day following the controls but may have negligible effects under northwesterly winds when local emissions dominate. To explore the contribution of different emission sectors and regions, we perform simulations with each source removed in turn. We find that residential and industrial sectors from neighbouring provinces dominate PM2.5 levels in Beijing during major pollution episodes but that local residential emissions and industrial or residential emissions from more distant provinces can also contribute significantly during some episodes. We then perform a structured set of perturbed emission simulations to allow us to build statistical emulators that represent the relationships between emission sources and air pollution in Beijing over the period. We use these computationally fast emulators to determine the sensitivity of PM2.5 concentrations to different emission sources and the interactions between them, including for secondary PM, and to create pollutant response surfaces for daily average PM2.5 concentrations in Beijing. We use these surfaces to identify the short-term emission controls needed to meet the national air quality target of daily average PM2.5 less than 75 µg m−3 for pollution episodes of different intensities. We find that for heavily polluted days with daily mean PM2.5 higher than 225 µg m−3, even emission reductions of 90 % across all sectors over Beijing and surrounding provinces may be insufficient to meet the national air quality standards. These results highlight the regional nature of PM pollution and the challenges of tackling it during major pollution episodes.

Assessment of climate change impact on wintertime meteorology over California using dynamical downscaling method with a bias correction technique

Climate change can potentially have great impacts on wintertime precipitation and stagnant conditions, which are critical for both water resources and wintertime particulate matter (PM), in California. This study utilizes the Weather Research and Forecasting model to dynamically downscale a bias-corrected coarse-resolution global climate model dataset from the Coupled Model Intercomparison Project Phase 5 (CMIP5) to a grid size of 4 × 4 km2 over California for a present (2003–2012) and a future (2046–2055) decade. Compared to the present climate, an increase in 2-m temperature (up to 2 K) and water vapor mixing ratio (up to 1 g/kg) and a decrease in planetary boundary layer height (up to 80 m) are projected by the 2050s for the entire state of California. The number of stagnant days over the San Joaquin Valley is expected to increase by approximately 6% in the future decade, indicating potential exacerbation of the winter PM issue in this region. The wintertime precipitation is projected to increase by up to 50% in northern California and, conversely, to decrease by up to 40% in southern California during 2046–2055. The solid phase precipitation is projected to decrease over mountain ranges with lower elevations despite an overall increase in total precipitation, while it is projected to increase over the eastern side of the Sierra Nevada with elevation over 2 km.

Role of sea fog over the Yellow Sea on air quality with the direct effect of aerosols.

In this study, we investigate the impact of sea fog over the Yellow Sea on air quality with the direct effect of aerosols for the entire year of 2016. Using the WRF-CMAQ two-way coupled model, we perform four model simulations with the up-to-date emission inventory over East Asia and dynamic chemical boundary conditions provided by hemispheric model simulations. During the spring of 2016, prevailing westerly winds and anticyclones caused the formation of a temperature inversion over the Yellow Sea, providing favorable conditions for the formation of fog. The inclusion of the direct effect of aerosols enhanced its strength. On foggy days, we find dominant changes of aerosols at an altitude of 150-200 m over the Yellow Sea resulted by the production through aqueous chemistry (~12.36% and ~3.08% increases in sulfate and ammonium) and loss via the wet deposition process (~-2.94% decrease in nitrate); we also find stronger wet deposition of all species occurring in PBL. Stagnant conditions associated with reduced air temperature caused by the direct effect of aerosols enhanced aerosol chemistry, especially in coastal regions, and it exceeded the loss of nitrate. The transport of air pollutants affected by sea fog extended to a much broader region. Our findings show that the Yellow Sea acts as not only a path of long-range transport but also as a sink and source of air pollutants. Further study should investigate changes in the impact of sea fog on air quality in conjunction with changes in the concentrations of aerosols and the climate.

Membangun Positive Brand Tentang Minuman Toak Produksi Warga Desa Hendrosari Kabupaten Gresik

The existences of traditional drink, Toak, is in stagnant condition and have less enthusiasts because of the wrong perception in the public about this traditional drink that made from the essence fermentation of siwalan fruit. Meanwhile, Sake, a traditional drink contains of alcohol from Japan that always serves in every traditional ceremony such as traditional wedding in Japan which is symbolizes unity / forming a new bound (source: jejakpena.wordpress.com). Because of those reasons, the writer conducted a research about how negative cognition which is cling on Toak produces by the villagers of Hendrosari, Gresik District turned into positive cognition because its effect can make the body of human warmed or refreshed. This research uses qualitative descriptive method such as, observation, data collection, and interview in order to found the distortion and also the solution by using “Cognitive Disonative” theory by Keon Festinger. The purpose of this research is to educating the tappers and Toak merchant, and also to suggests the Government of Gresik District to make Toak become an iconic product which is serves to the guest / visitor of the District of Gresik. The result is to build a positive cognition by branding the image of Toak as a traditional drink even though in the middle of Covid-19 pandemy by using digital marketing (Instagram), socialize a traditional drink in a package of bottle glass with a “Nosari” logo, complete with the information of traditional drink benefit and its contents along with the serving method so the drink can be enjoy by guest, visitor, or tourist.

Lysis of arterial thrombi by perfusion of N,N'-Diacetyl-L-cystine (DiNAC).

The search persists for a safe and effective agent to lyse arterial thrombi in the event of acute heart attacks or strokes due to thrombotic occlusion. The culpable thrombi are composed either primarily of platelets and von Willebrand Factor (VWF), or polymerized fibrin, depending on the mechanism of formation. Current thrombolytics were designed to target red fibrin-rich clots, but may be not be efficacious on white VWF-platelet-rich arterial thrombi. We have developed an in vitro system to study the efficacy of known and proposed thrombolytic agents on white clots formed from whole blood in a stenosis with arterial conditions. The agents and adjuncts tested were tPA, ADAMTS-13, abciximab, N-acetyl cysteine, and N,N'-Diacetyl-L-cystine (DiNAC). Most of the agents, including tPA, had little thrombolytic effect on the white clots. In contrast, perfusion of DiNAC lysed thrombi as quickly as 1.5 min, which ranged up to 30 min at lower concentrations, and resulted in an average reduction in surface area of 71 ± 20%. The clot burden was significantly reduced compared to both tPA and a saline control (p<0.0001). We also tested the efficacy of all agents on red fibrinous clots formed in stagnant conditions. DiNAC did not lyse red clots, whereas tPA significantly lysed red clot over 48 h (p<0.01). These results lead to a novel use for DiNAC as a possible thrombolytic agent against acute arterial occlusions that could mitigate the risk of hyper-fibrinolytic bleeding.

Effect of Fluid Flow on the Corrosion Performance of as-Cast and Heat-Treated Nickel Aluminum Bronze Alloy (UNS C95800) in Saline Solution

In this work, the corrosion behavior and surface reactivity of as-cast and heat-treated nickel aluminum bronze casting alloy (UNS C95800) in 3.5 wt% NaCl solution is investigated under stagnant and flow conditions. Increasing flow rate conditions are simulated using a rotating disk electrode from 0 to 9000 revolutions per minute (rpm). Optical micrographs confirm the decrease in the phase fraction of corrosion-sensitive β phase in the microstructure of C95800 after annealing, which, in turn, enhances the corrosion resistance of the alloy. Electrochemical studies including open circuit potentiometry, potentiodynamic polarization, and electrochemical impedance spectroscopy are performed to assess the effect of flow rate and heat treatment on the corrosion of samples at 25 and 40 °C in 3.5 wt% NaCl solution. For both as-cast and heat-treated samples, increasing the flow rate (i.e., electrode rotating rate) linearly reduces the corrosion resistance, indicating that the metal dissolution rate is significantly affected by hydrodynamic flow. Increasing the solution temperature negatively impacts the corrosion behavior of the as-cast and heat-treated samples at all flow conditions.

The Role of Cassava Leaf Extract as Green Inhibitor for Controlling Corrosion and Scale Problems in Cooling Water Systems

The addition of synthetic corrosion and scale inhibitors in a recirculating cooling water system is a well-known method to defeat corrosion and scale problems. In this work, we utilize the extract from cassava leaf, which is agricultural waste in Thailand as a green inhibitor. Corrosion inhibition efficiency with using cassava leaf extract (CLE) for mild carbon steel was investigated in a simulated cooling water solution under both stagnant and hydrodynamic conditions. A mock-up of a recirculating cooling water system was custom-built to imitate the hydrodynamic conditions used in industry. Effects of CLE concentration (0, 50, 100, 200, 400, 600, and 800 ppm) and temperature (35 °C, 45 °C, and 55 °C) on corrosion inhibition efficiency were investigated. Increasing the CLE concentration increased its inhibition efficiency. In the case of stagnant conditions, the CLE showed a corrosion inhibition efficiency of 97.4% with 800 ppm CLE at 35 °C. The CLE performed as an anodic inhibitor. A decrease in inhibition efficiency was observed when the temperature was increased. For the hydrodynamic conditions with a flow rate of 34 L min−1 at 55 °C, a corrosion inhibition efficiency of 75.7% was seen with 200 ppm CLE. A scale inhibition efficiency of the CLE was investigated at concentrations of 0, 200, 800, and 2000 ppm. A 76.1% CaCO3 scale inhibition efficiency was obtained with 2000 ppm CLE. A change in the CaCO3 morphology due to the adsorption of the CLE inhibited scale formation.

The role of surfaces on amyloid formation

Interfaces can strongly accelerate or inhibit protein aggregation, destabilizing proteins that are stable in solution or, conversely, stabilizing proteins that are aggregation-prone. Although this behaviour is well-known, our understanding of the molecular mechanisms underlying surface-induced protein aggregation is still largely incomplete. A major challenge is represented by the high number of physico-chemical parameters involved, which are highly specific to the considered combination of protein, surface properties, and solution conditions. The key aspect determining the role of interfaces is the relative propensity of the protein to aggregate at the surface with respect to bulk. In this review, we discuss the multiple molecular determinants that regulate this balance. We summarize current experimental techniques aimed at characterizing protein aggregation at interfaces, and highlight the need to complement experimental analysis with theoretical modelling. In particular, we illustrate how chemical kinetic analysis can be combined with experimental methods to provide insights into the molecular mechanisms underlying surface-induced protein aggregation, under both stagnant and agitation conditions. We summarize recent progress in the study of important amyloids systems, focusing on selected relevant interfaces.

Severe haze events in the Indo-Gangetic Plain during post-monsoon: Synergetic effect of synoptic meteorology and crop residue burning emission

In recent years, the frequent occurrence of haze events in the Indo-Gangetic Plain (IGP) during crop residue burning period has caused a serious reduction in atmospheric visibility and deteriorated air quality. The present study is carried out to investigate the haze event observed in IGP in Nov 2017 using ground-based observations, satellite data and synoptic meteorology to understand the possible factors responsible for haze formation. PM2.5 (particulate matter with aerodynamic diameter ≤ 2.5 μm) concentrations and Air Quality Index (AQI) at two sites (Agra and Delhi) situated in the central Indo-Gangetic Plain (CIGP) showed a sudden increase in PM2.5 concentrations and deteriorated air quality during 7–14 Nov. To monitor the variation of particulate matter (PM) in IGP, PM2.5 and PM10 (particulate matter with aerodynamic diameter ≤ 10 μm) concentrations were monitored at 22 stations in 12 cities of IGP during 1–15 Nov which also showed an increase in PM concentrations during haze event (7–14 Nov). Crop residue burning activities in north-west Indo-Gangetic Plain (NW-IGP) were observed during haze event. Synoptic weather conditions of IGP identified using geopotential height and wind at 700 hPa showed high-pressure systems and low winds in IGP favoring stagnant conditions during haze event. A detailed analysis of the variation of pollutants and meteorology was carried out at Agra. Ozone (O3), carbon monoxide (CO), sulphur dioxide (SO2) and nitrogen oxides (NOx) showed higher concentrations during haze event along with lower temperature, low wind speed and high relative humidity. Aerosol ionic composition showed a higher contribution (~84%) of Cl−, NO3−, SO42− and NH4+ to total soluble ions suggesting secondary aerosol formation during haze event.

A Possible Linkage between Dust Frequency and the Siberian High in March over Northeast Asia

Spring dust frequency in northeast Asia has been investigated using various approaches to understand the mechanisms of dust emission and transport. However, little attention has been paid to the linkage between dust activity and the Siberian High (SH), particularly when the SH pressure system is highly variable. In this study, we characterize the possible physical mechanisms of dust emission and transport associated with the Siberian High Intensity (SHI) and Siberian High Position Index (SHPI) in March using 18 years of ground-based observations and reanalysis data. We found that when the SHI was strong and the SH’s center was farther east (“Strong–East period”), surface and atmospheric temperatures were cooler than when the SHI was weak and the SH’s center was farther west (“Weak-West period”), due to anomalous anticyclonic pressure and strong easterlies. As a result, a reduction in the meridional temperature gradient in the lower atmosphere suppressed dust emission and transport, due to stagnant atmospheric conditions. This anomalous anticyclonic pressure in the Strong-East case seems to reduce the development of extratropical cyclones (ETC) in northeast Asia, leading to a less effective dust transport. A case study with composite analysis also showed a similar physical mechanism: stagnant air accompanying weakened westerlies in the Strong-East period suppressed dust transport to South Korea. Our findings reveal that the intensity and position of the SH can be utilized to identify spring transboundary air pollutants in northeast Asia.

Investigation of Nanofluids Circulating in a Volumetric Solar Receiver

Abstract Single-wall carbon nanohorn (SWCNHs)-based nanofluids have been proven to be promising media for the direct absorption of solar radiation due to their favorable optical properties and potential low cost. Still their stability in real working conditions is an open issue because they have been studied mainly under stagnant conditions, while limited information is available on the performance of these nanofluids during circulation in real systems. In the present work, the optical behavior of SWCNH-based nanofluids has been investigated with the aim of detecting possible effects of circulation and exposure to radiation, avoiding other effects such as thermal instability. An ad hoc experimental apparatus has been realized to check the stability of the circulating fluids in situ using a novel approach based on the use of pyranometers. Three suspensions are tested, two are surfactant stabilized and one is based on preoxidized and functionalized SWCNHs. Efficiency values higher than 90% were measured for more than 65 h of circulation. The effects of fluid circulation and exposure to solar radiation have been addressed, finding that the absorption efficiency decreases during tests due to the degradation of the optical properties and the nanofluid circulation is the main responsible for such degradation.

Severe Corrosion of Carbon Steel in Oil Field Produced Water Can Be Linked to Methanogenic Archaea Containing a Special Type of [NiFe] Hydrogenase.

Methanogenic archaea have long been implicated in microbially influenced corrosion (MIC) of oil and gas infrastructure, yet a first understanding of the underlying molecular mechanisms has only recently emerged. We surveyed pipeline-associated microbiomes from geographically distinct oil field facilities and found methanogens to account for 0.2 to 9.3% of the 16S rRNA gene sequencing reads. Neither the type nor the abundance of the detected methanogens was correlated with the perceived severity of MIC in these pipelines. Using fluids from one pipeline, MIC was reproduced in the laboratory, both under stagnant conditions and in customized corrosion reactors simulating pipeline flow. High corrosion rates (up to 2.43 mm Fe0 · yr-1) with macroscopic, localized corrosion features were attributed to lithotrophic, mesophilic microbial activity. Other laboratory tests with the same waters yielded negligible corrosion rates (<0.08 mm Fe0 · yr-1). Recently, a novel [NiFe] hydrogenase from Methanococcus maripaludis strain OS7 was demonstrated to accelerate corrosion. We developed a specific quantitative PCR (qPCR) assay and detected the gene encoding the large subunit of this hydrogenase (labeled micH) in corrosive (>0.15 mm Fe0 · yr-1) biofilms. The micH gene, on the other hand, was absent in noncorrosive biofilms, despite an abundance of methanogens. Reconstruction of a nearly complete Methanococcus maripaludis genome from a highly corrosive mixed biofilm revealed micH and associated genes in nearly identical genetic configuration to that in strain OS7, thereby supporting our hypothesis that the encoded molecular mechanism contributed to corrosion. Lastly, the proposed MIC biomarker was detected in multiple oil fields, indicating a geographically widespread involvement of this [NiFe] hydrogenase in MIC.IMPORTANCE Microorganisms can deteriorate built environments, which is particularly problematic in the case of pipelines transporting hydrocarbons to industrial end users. MIC is notoriously difficult to detect and monitor and, as a consequence, is a particularly difficult corrosion mechanism to manage. Despite the advent of molecular tools and improved microbial monitoring strategies for oil and gas operations, specific underlying MIC mechanisms in pipelines remain largely enigmatic. Emerging mechanistic understanding of methanogenic MIC derived from pure culture work allowed us to develop a qPCR assay that distinguishes technically problematic from benign methanogens in a West African oil field. Detection of the same gene in geographically diverse samples from North America hints at the widespread applicability of this assay. The research presented here offers a step toward a mechanistic understanding of biocorrosion in oil fields and introduces a binary marker for (methanogenic) MIC that can find application in corrosion management programs in industrial settings.

Wind and greenery effects in attenuating heat stress: A case study

This paper aims to assess the effects of urbanization on heat stress comparing two neighbourhoods in the tropical city of Rio de Janeiro, Brazil, that differ in terms of building density and vegetation cover. The outdoor heat stress was evaluated by the Wet Bulb-Globe Temperature (WBGT) Index, which considers the combined effect of air temperature, relative humidity, solar radiation and wind speed, during the year of 2016. The urban neighbourhood presented statistically (p < 0.01) higher WBGT levels (mean value 23.48 °C), than the suburban neighbourhood (mean value 22.0 °C). The results highlighted the effect of low wind velocities on heat stress in the urban environment over 75% of the time. Building spacing and street orientation considering the most frequent wind directions must be taken into account during the urban planning process. Otherwise stagnant air conditions in urban environments become a common feature that cannot be reverted. Under such circumstances, green areas such as pocket parks, green roofs and green walls should be implemented to mitigate heat stress. Public policies for many neighbourhoods in Brazilian cities are necessary to increase vegetated areas aiming to improve conditions of well-being. • Vegetation played a significant role in controlling urban heat fluxes. • Considerable differences in heat stress conditions were observed between the two areas. • Urban planning guidelines should recommend green spaces and street orientation to optimise wind flow.