High O2 Concentrations Research Articles

Assessing SO2, NO2 and O3 in rural areas of the North West Province

Air quality monitoring has been lacking in the rural and western North West Province. Here ambient sulphur dioxide (SO2), nitrogen dioxide (NO2) and ozone (O3) concentrations, monitored with passive samplers at 10 sites, are presented. Widespread SO2 and NO2 problems weren’t observed. However, regular O3 standard limit exceedances are likely across the province. Increased SO2 and NO2 concentrations in the colder and drier months were evident. Inversion layer trapping of low-level emissions during the colder months and open biomass burning in the drier months increased ground level pollutant concentrations. Wet deposition of SO2 and NO2, and enhanced SO2 conversion to particulate sulphate, result in lower wet season concentrations. O3 concentrations were lower from May to July and higher from August to March. Three phenomena contributed to this. Firstly, shorter daylight hours (less photochemistry) and secondly, lower biogenic volatile organic compound (O3 precursors) concentrations during the colder months. Thirdly, the late winter/early spring open biomass burning peak lead to elevated carbon monoxide (CO) concentration (also an O3 precursor). Spatial patterns indicated higher SO2 concentrations in the west, due mainly to industrial emissions. The NO2 spatial map indicated two areas of higher concentration, i.e. Bapong in the east due mainly to industrial emissions, and Taung with its higher population density. The O3 spatial map was almost the inverse of NO2. The lower O3 and higher NO2 around Taung showed that O3 is titrated there. Additionally, the results indicate that non-point source emissions of NO2 are high enough to results in exceedances of the O3 standard limit. Overlay back trajectory maps showed that sites in the east are more frequently impacted by pollution transported from the Mpumalanga Highveld, Vaal Triangle and the Johannesburg-Pretoria megacity if compared to the west. Conversely, cleaner air masses impact the west more than sites in the east.

Insight into the Effect of the Continuous Testing and Aging on the so2 Sensing Characteristics of a YSZ (Yttria-stabilized Zirconia)-Based Sensor Utilizing ZnGa2O4 and Pt Electrodes

IntroductionSO2 concentration detection in harsh environment is still a challenge because the present technology is based on large-scale instrument, which is expensive and can’t monitor in real time. Recently, gas sensor with low cost and the ability of in-situ measurement has been used to SO2 detection. Due to high sensing performance, reliable stability and acceptable humidity resistance, the mixed potential sensor based on YSZ was expected to achieve the real-time detection in harsh environment [1]. Method Fabrication and measurement of the gas sensor The sensor was fabricated utilizing 8mol% Y2O3-doped YSZ plate (2 mm×2 mm square, 0.3 mm thick, provided by Anpeisheng Corp. China). A point-shaped and a narrow stripe-shaped Pt electrode (PE) were formed on two ends of the YSZ plate using a commercial Pt paste (Sino-platinum Metals Co. Ltd.), and sintered at 950°C. The paste which was mixed by a minimum quantity of deionized water and the sensing materials ZnGa2O4. Next, the resultant paste was applied on the point-shade Pt to form stripe-shaped ZnGa2O4 electrode (ZE). Afterward, the device was annealed at 800°C to make a good contact between the sensing electrode and electrolyte. A Pt heater and a linear DC Power Supply were used to provide required heat to regulate the operating temperature of the sensor. Sulfuration process In order to further investigate the sensing mechanism of the sensor, we added a sulfuration experiment. The sulfuation process is as following: The sensor was put into a 1L chamber with a mixture of air and 100 ppm SO2 for 24 hrs, the temperature of the sensor maintain at 650°C during this process. When time is up, put the sensor into a 1L chamber with fresh air and begin to measure the sensing performance of the sensor after sulfuration. Results and Conclusions YSZ-based mixed potential sensor with ZnGa2O4 and Pt electrodes (ZE and PE) was developed for the SO2 detection. The effects of long-term aging and continuous test on various properties of the electrode materials had been investigated and characterized. Some interesting phenomenon were found that when the sensor exposed to the relative high concentration SO2 with air, the response direction was opposite to that exposing to low concentration SO2 as shown in Fig. 1. Moreover, with the last of the testing time, the responses of the sensor to all concentration SO2 were opposite to that in the original state. Hence, giving a reasonable explanation is one of the most important purposes in this paper. We have proved that the PtS was produced during the testing and aging process. According to the Y. shimizu’s work [2], most of metal mono-sulfides performed a high electrochemical catalytic activity to SO2. Hence, we speculated that the mono-sulfides PtS also has a high electrochemical catalytic activity to SO2. In this case, when measuring lower concentration SO2, the diffusion rate is a slow value. Due to the Pt’s high catalytic activity to SO2, SO2 react with Pt electrode and changed to PtS, which adhere to the Pt electrode surface. The process was clearly exhibited in the bottom half of Fig. 1. This process sharply decreased the SO2 concentration reaching TPB of PE, and then caused the ΔVPE approaching 0. On the other hand, ZnGa2O4 electrode had a response to SO2 and according to the mixed potential mechanism, the ΔVZE should be a negative value. However when measuring higher SO2 concentration, Pt has changed to PtS, which decreased the contact area, and then decreased the catalytic activity to SO2. Because of the much higher electrochemical catalytic activity of PtS at PE to SO2 than that of ZnGa2O4, the response at PE was much higher than that at ZE. Hence, the reversed response characteristics occurred as shown in the second response and recovery transient of Fig. 1. Furthermore, with continuous testing and aging, more and more sulfur element was deposited to the Pt electrode and the critical concentration deceased, finally, all of the ΔV were changed to the positive values as shown in the third of Fig. 1. Moreover, the sensor after sulfuration process (the detail of the sulfuration process was given in the last part) also performed similar sensing properties to the sensor with continuous testing and aging process, which indicated that the produced PtS should be the reason for that the sensor performed reversed sensing performances. In addition, the sensor after sulfuration can detect 0.05-500 ppm SO2 with the sensitivity being 5 mV/decade to 0.05-1 ppm and 41 mV/decade to 1-500 ppm. The sensor also had a reliable stability during the continuous measurement.

Improved agreement between N2 and SF6 multiple-breath washout in healthy infants and toddlers with improved EXHALYZER D sensor performance.

Recent studies indicate limited utility of nitrogen multiple-breath washout (N2MBW) in infancy and advocate for using sulfur hexafluoride (SF6) MBW in this age-group. Modern N2MBW systems, such as EXHALYZER D (ECO MEDICS AG, Duernten, Switzerland), use O2 and CO2 sensors to calculate N2 concentrations (in principle, N2% = 100 - CO2% - O2%). High O2 and CO2 concentrations have now been shown to significantly suppress signal output from the other sensor, raising apparent N2 concentrations. We examined whether improved EXHALYZER D N2 signal, accomplished after thorough examination of this CO2 and O2 interaction on gas sensors and its correction, leads to better agreement between N2MBW and SF6MBW in healthy infants and toddlers. Within the same session, 52 healthy children aged 1-36 mo [mean = 1.30 (SD = 0.72) yr] completed SF6MBW and N2MBW recordings (EXHALYZER D, SPIROWARE version 3.2.1) during supine quiet sleep. SF6 and N2 SPIROWARE files were reanalyzed offline with in-house software using identical algorithms as in SPIROWARE with or without application of the new correction factors for N2MBW provided by ECO MEDICS AG. Applying the improved N2 signal significantly reduced mean [95% confidence interval (CI)] differences between N2MBW and SF6MBW recorded functional residual capacity (FRC) and lung clearance index (LCI): for FRC, from 26.1 (21.0, 31.2) mL, P < 0.0001, to 1.18 (-2.3, 4.5) mL, P = 0.5, and for LCI, from 1.86 (1.68, 2.02), P < 0.001, to 0.44 (0.33, 0.55), P < 0.001. Correction of N2 signal for CO2 and O2 interactions on gas sensors resulted in markedly closer agreement between N2MBW and SF6MBW outcomes in healthy infants and toddlers.NEW & NOTEWORTHY Modern nitrogen multiple-breath washout (N2MBW) systems such as EXHALYZER D use O2 and CO2 sensors to calculate N2 concentrations. New corrections for interactions between high O2 and CO2 concentrations on the gas sensors now provide accurate N2 signals. The correct N2 signal led to much improved agreement between N2MBW and sulfur hexafluoride (SF6) MBW functional residual capacity (FRC) and lung clearance index (LCI) in 52 sleeping healthy infants and toddlers, suggesting a role for N2MBW in this age-group.

Reducing post‐harvest losses and improving quality in sweet corn (Zea mays L.): challenges and solutions for less food waste and improved food security

AbstractDemand for fresh‐cut fruit and vegetables is increasing, in the face of global population growth and new interest in plant‐based diets. At the same time, year‐round supply across the world of popular vegetables means that post‐harvest losses, which can be significant, need to be minimized in the face of complex global supply chains and markets. Sweet corn (Zea mays L.) is harvested before physiological maturity when the kernel has high water and sugar concentrations making it a very perishable fresh produce and effective post‐harvest handling essential to reduce losses and ensure quality. Taste, aroma and colour are the main customer‐appreciated characteristics, hence the most important to preserve. Among the sweet corn post‐harvest disorders, loss of sweetness, dehydration, fungal growth and post‐cooking browning are the biggest issues impacting sweet corn quality, leading to post‐harvest losses. The critical factor driving these losses in sweet corn is temperature. Sweet corn is not a chilling sensitive product and has high sugar content. For this reason, temperatures as close as 0°C and the appropriate use of packaging films to create an altered gas composition with high CO2 and low O2 concentrations can significantly prevent post‐harvest decay. The use of low temperatures and effective choice of appropriate packaging films can control sweet corn respiration rates and prevent microorganism growth, subsequently delaying quality loss. This comprehensive review assembles a description of the most customer‐appreciated sweet corn characteristics. And it describes the major sweet corn post‐harvest challenges and provides a summary of four approaches to improve post‐harvest quality in this popular fresh‐cut vegetable.

Enhanced volatile fatty acids accumulation in anaerobic digestion through arresting methanogenesis by using hydrogen peroxide.

Volatile fatty acids (VFAs) can be accumulated as a final product of anaerobic digestion via arresting methanogenesis. Herein, hydrogen peroxide (H2 O2 ) was studied to inhibit methanogenesis for enhancing VFA accumulation with glucose as a substrate. The addition of 0.06 wt.% H2 O2 significantly reduced methane production and led to a VFAs concentration of 1233.1±55.9mgL-1 , much higher than 429.3±5.6mgL-1 in the control that did not have H2 O2 addition. The dominated VFAs with H2 O2 were acetic acid and propionic acid. A low H2 O2 dosage of 0.03 wt.% produced 466.3±3.9mgL-1 more VFAs than that of O2 addition at the similar (theoretical) dosage, but when the dosage was relatively higher, the VFA accumulation with O2 addition became more than that with H2 O2 addition, likely because of stronger oxidation of VFAs by the overly added H2 O2 . A hypothetical mechanism for H2 O2 inhibition suggests that at a low H2 O2 concentration the inhibition is mainly toward methanogenesis to limit their consumption of VFAs and a high H2 O2 concentration starts to inhibit hydrolysis and acidogenesis and/or oxidize VFAs. Those results encourage further exploration of H2 O2 -based arresting methanogenesis for VFAs production.

Blueberry fruit quality and control of blueberry maggot (Rhagoletis mendax Curran) larvae after fumigation with sulfur dioxide

Postharvest fumigation of fruits and vegetables is an important tool for managing pests and diseases that can cause devastating loss if not properly controlled. Sulfur dioxide (SO2) may have promise as replacement for methyl bromide, which is expected to be phased out. However, SO2 is known to cause injury to small fruit such as table grapes (Vitis vinifera L.). We extend previous research on SO2 fumigation by focusing on an economically important fruit pest genus and through quantitative and qualitative measurements of highbush blueberry (Vaccinium corymbosum L.) fruit bleaching. This study assesses fruit damage due to SO2 fumigation at concentrations ranging 0–2.2 % (v/v) as well as the effectiveness of SO2 as a fumigant prior to cold storage for control of blueberry maggot, Rhagoletis mendax Curran. We show that fruit quality traits such as firmness, total soluble solid content, and titratable acidity are largely unaffected except at the highest SO2 concentration (2.2 %). SO2 caused bleaching and discoloration of blueberry fruit in a dose-dependent manner. Damage was also cultivar-dependent, with cv ‘Bluecrop’, and ‘Jersey’ more susceptible than ‘Draper’, ‘Elliott’, and ‘Liberty’. We show that R. mendax can be effectively controlled using a short-term (2 h), high concentration (22,000 μL L−1) SO2 fumigation followed by >14 d of cold storage at 0.5 °C. However, this treatment for control of R. mendax would likely result in damage, affecting fruit marketability.

Removal of SO2 from smelting flue gas by using copper tailings with MnSO4: factors optimization by response surface methodology

The abatement of SO2 and the utilization of copper tailings are identified as two attention-attracting environmental issues in the copper smelter. In this study, to improve the flue gas desulfurization performance and the utilization of copper tailings, SO2 removal from smelting flue gas by using copper tailings combined with MnSO4·H2O was investigated. The effects of operation variables, including inlet SO2 concentration, absorption temperature, slurry concentration, and MnSO4·H2O amount, on the flue gas desulfurization performance were studied based on the response surface method. It was found that the effect of operation variables on SO2 removal follows the descending order: the inlet SO2 concentration, MnSO4·H2O concentration, absorbent temperature, and solid-liquid ratio. The interaction between the inlet SO2 concentration and MnSO4·H2O concentration is an important factor for breakthrough sulfur capacity. Elevated temperature and high initial SO2 concentration inhibited the efficient removal of SO2. Moreover, a proposed equation exhibits good consistency in the prediction for the breakthrough sulfur dioxide capacity. Therefore, the results can provide a reliable reference and basis for industrial application for flue gas desulfurization with copper tailings.

Sulfur Contamination and Environmental Effects: A Case Study of Current SO2 Industrial Emission by Biomonitoring and Regional Post-mining hot-spots

The presence of sulfur in the environment is an important macroelement for plant growth but becomes harmful in excessive amounts. The previous century saw rising levels of high SO2 concentrations (stemming from fossil fuel combustion) and wet deposition from acid rain, causing the intensification of forest die-back. Air pollution can be controlled or measured by biomonitoring. Despite recent reductions in SO2 emissions, urban and industrial areas are still at risk from high sulfur contamination. Open-cast lignite and sulfur borehole mining play a pivotal role in the regional scale of ecosystem contamination and acid mine drainage. Consequently, these aspects are unique for assessing the impact of extreme S contamination on soil properties changes, the vegetation effect, and biogeochemical cycles. We presented i) current SO2 pollution based on S concentration in pine needles, and ii) a comprehensive study of soil properties, as well as plant reactions to excessive sulfur concentration in the restored forest ecosystem of a former sulfur mine.

Benthic diffusive fluxes of organic and inorganic carbon, ammonium and phosphates from deep water sediments of the Baltic Sea

In this study, Baltic Sea sediments, as a source of dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), ammonium (NH4+), and phosphates (PO43−), were investigated based on samples obtained in 2017 and 2018, shortly after a sequence of inflows from the North Sea that occurred between 2014 and 2017. Two different data sets (I and II) were used to assess benthic diffusive fluxes and thus elucidate both the temporal conditions at the time of sampling (data set I) and the diffusion potential of the sediments (data set II). The estimated fluxes were characterized by a high spatial variability within the whole Baltic Sea and ranged between −0.01 and 3.33 mmol m−2 d−1 for DIC, −0.02 and 0.44 mmol m−2 d−1 for DOC, −40.5 and 1370.1 µmol m−2 d−1 for NH4+, and −5.9 and 60.9 µmol m−2 d−1 for PO43−. The estimated benthic diffusive fluxes indicated a high potential for DIC, DOC, NH4+, and PO43− release from Baltic Sea sediments. The high O2 concentrations in the water column of the Gulf of Bothnia together with major Baltic inflows (MBIs) bringing oxygenated seawater to the Baltic Proper and to some extent the Eastern Gotland Basin regulate the amounts of chemicals released from the sediment. Our study showed that a sequence of inflows has greater impact on the diminution of diffusive fluxes than does a single MBI and that the sediments of the Baltic Proper, even under the influence of inflows, are an important source of C, N, and P (159 kt yr−1 for DIC+DOC, 6.3 kt yr−1 for N-NH4+ and 3.7 kt yr−1 for P-PO43−) that should be considered in regional budget estimations.

Simulation of SO2 absorption and performance enhancement of wet flue gas desulfurization system

At the present moment wet flue gas desulfurization systems (WFGD) are widely used in the SO2 emitting industries. With the improvement of the SO2 emission standards and the use of fuel with high sulfur content, there is an urgent need to develop advanced modelling tools to explore the enhancing method of SO2 absorption process on the condition of flue gas with high SO2 concentration. In this study, a detailed mathematical model of tray scrubbers, which are adopted in several China’s power plants in order to treat SO2 rich flue gas, is developed to investigate the influencing factors of the SO2 absorption process. The model is validated by an experiment using pilot-scale WFGD experimental system and can describe the SO2 absorption process in WFGD to a satisfactory level. The influence factors of SO2 absorption of droplets and in spray tower are studied through the model. The effects of pH and tray on desulfurization efficiency are analyzed. Using the tray scrubber is better in order to realize the desulfurization of flue gas with high SO2 concentration rather than adjusting the pH of the slurry. This model can be regarded as a useful tool for equipment selection and operation optimization of WFGD system.

An Electrochemical and Spectroscopic Study of Surfaces on Bronze Sculptures Exposed to Urban Environment.

Polluted urban environment enhances dissolution of patina and underlying bronze material of recent and historical bronze sculptures exposed outdoors. In this work, two bronze statues, situated in one of the most polluted Croatian cities, were examined in order to characterize composition of patina and its electrochemical stability. The composition of patina on several positions on each sculpture was determined by EDS, Raman spectroscopy, and FTIR measurements. Electrochemical impedance spectroscopy measurements were conducted in order to evaluate the corrosion stability of both patina and underlying bronze. Results obtained in this work show that the two examined bronze sculptures were covered with patina layer that was mainly composed of copper sulfides and sulphates, which is in accordance with the high concentrations of H2S and SO2 in the atmosphere. However, the variations in the appearance of FTIR and Raman spectra revealed that the amount of each species differed from spot to spot, as well as the fact that other compounds, such as carbonates, were present at some areas. This difference in patina composition was reflected in electrochemical behavior as observed by electrochemical impedance spectroscopy.

Engineering application of desulfurization and denitrification comprehensive purification technology for activated coke

AbstractThis article discusses the desulfurization and denitrification integrated purification technology for activated coke. This technology has been widely used in globally due to its ability to simultaneously remove NOx, SO2, dioxin, and dust from the flue gas. The approach discussed adopts a cross‐flow method in which the activated coke flows from the top to the bottom in the adsorption tower, and the flue gas passes through the activated coke bed horizontally from the side. To create a more economically appealing solution, the waste heat recovery system is optimized and a regeneration gas processing system is added to recycle the gas with a high concentration of SO2. In this process, first desulfurization and then denitrification. The denitrification process is performed by selective catalytic reduction of NOx with NH3 reaction (NH3‐SCR). The results show that under the flue gas condition (NOx = 300 mg/Nm3 and SO2 = 200 mg/Nm3), SO2 is almost completely removed and the NOx removal efficiency is greater than 80%. After SO2 adsorption, the activated coke can be regenerated in a regeneration furnace at 400–450°C and the highly concentrated SO2 produced during the regeneration process can be further used for the production of ammonium sulfate. The purpose of the regeneration reaction of activated coke is to reactivate and recover the activated coke. Finally, the cost analysis results of the system show that the desulfurization and denitrification integrated purification technology for activated coke has excellent economic benefits.

Gas emission study of a crop residue burning machine

Crop residue burning is a common agriculture practice to eliminate post-harvest vegetative material, which hinders the seedling of the next crop. A prototype of a crop residue burning machine was developed and equipped with six LPG burners. The burners were designed as a forced-draft burner where the air was supplied by a blower/pump. While open field burning is a practical and economical practice for controlling insects, diseases, and weeds, the environmental risks of this activity are an issue. Open biomass burning is a major source of global air pollutants and has a major impact on global climate change. This study aimed to estimate the concentration of CO and NOx emitted from the combustion using this prototype. CO and NOx are important indirect greenhouse gases that affect the formation of tropospheric ozone or change the lifetime of methane. The air pollutants were measured using ECOM-EN2. The gas velocity, static pressure, and gas concentration were sampled with 1 minute’s average sampling time. Gas emission study shows a high concentration of O2 in the flue gas. The recorded CO and NOx concentration exceeds the concentrations that regulated by EPA NAAQS. The average combustion efficiency of 98.0±0.3%, the highest emission factors for CO, NO, and NO2 are 57, 3.7, and 0.5 lb/acre, respectively.

Effect of SO2 and SO3 on the distribution of Na/S/Cl and ashes characteristics of Zhundong coal during circulating fluidized bed O2/CO2 combustion

The high concentration of SO2 and SO3 under oxy-fuel combustion atmosphere is conducive to the sulfation of alkali metals. In order to investigate the effect of SO2 and SO3 on the distribution of Na/S/Cl and ashes characteristics of Zhundong coal during oxy-fuel combustion, a series of experiments were carried out in a 50 kW CFB oxy-fuel combustor system. The results showed that both SO2 and SO3 could realize the sulfation reaction of NaCl. It would enhance the distribution of sodium to the bottom ash and the circulating ash, the chlorine to the flue gas, so as to reduce the content of sodium and chlorine in deposit. In addition, the contents of Ca and Mg increased in the deposits and decreased in the fly ashes as the SO2 and SO3 were added, while the contents of Fe were all decreased in the deposits and fly ashes. Compared with SO2, SO3 is more prone to the sulfation reaction. While increasing the addition of SO2 and SO3 could strengthen the sulfation reaction. In addition, the deposit and fly ash generated by Zhundong coal combustion could be divided into two parts: particles less than 10 μm formed by condensation of sodium, chlorine and other components; particles larger than 10 μm formed by crushing of coal ash. Introducing SO2 and SO3 made the surface structure of deposit more porous, but the BET surface area of fly ash declined. There was no obvious difference of particle size distribution of deposit.

Association between ambient air pollution and high-risk pregnancy: A 2015–2018 national population-based cohort study in Korea

BackgroundSeveral studies have indicated that prenatal exposure to ambient air pollution is associated with an increased risk of gestational diabetes mellitus, hypertensive disorder during pregnancy, preterm birth, and stillbirth. However, no previous study has focused on the association between the number of pregnancy complications and exposure to ambient air pollution. ObjectivesTo investigate the association between prenatal exposure to ambient air pollutants and the number of pregnancy complications in high-risk pregnancies. MethodsWe collected data on gestational diabetes mellitus, hypertensive disorder during pregnancy, preterm birth, and stillbirth from the National Health Information Databases, provided by the Korean National Health Insurance Service.R To assess individual-level exposure to air pollutants, a spatial prediction model and area-averaging approach were used. ResultsFrom 2015 to 2018, data of 789,595 high-risk pregnancies were analyzed. The ratio of gestational diabetes mellitus in the country was the highest, followed by preterm birth, hypertensive disorder during pregnancy, and stillbirth. Approximately 71.7% of pregnant women (566,143) presented with one pregnancy complication in identical pregnancies, 27.5% (216,714) presented with two, and 0.9% (6738) presented with three or more. Multiple logistic regression models with adjustments for age, residence, and income variables indicated that the risk of having two or more pregnancy complications was positively associated with the exposure to higher levels of PM10 (odds ratio [OR], 1.11; 95% confidence interval [CI], 1.09–1.12) and PM2.5 (OR, 1.14; 95% CI, 1.12–1.15). The highest quartile presented higher odds of two or more pregnancy complications compared with the lower three quartiles of PM10, PM2.5, CO, NO2, and SO2 exposures (p < 0.001). ConclusionThe results indicate that the risk of pregnancy complications is positively associated with the exposure to the high concentrations of PM10, PM2.5, CO, NO2, and SO2.

A novel fluorescent probe for rapid detection of sulfur dioxide in living cells.

Sulfur dioxide is one of the reactive sulfur species, which has significant physiological functions in cells. Some physiological processes are closely related to SO2 in organisms, and the high concentration of SO2 in living cells can cause many diseases. In order to investigate the unique function of SO2 at the subcellular level, developing a molecular tool which could detect of SO2 within organelles is imperative. Hence, we developed a cationic dye named HQ-SO2 as a new fluorescent probe to specifically monitor SO2 , which was easy to obtain through one-step reaction. It took Michael addition reaction as the mechanism of reaction for detection of SO2 . In addition, this probe showed a series of highly favorable properties such as rapid response rate, low cytotoxicity, high selectivity, low detection limit, and good photostability, which enabled the probe to track SO2 in living cells.

Detailed analysis on sterculia foetida kernel oil as renewable fuel in compression ignition engine

This work briefs the ability of Sterculia foetida methyl ester (SFME) as an alternate fuel in determining the engine characteristics. Non-edible nature of the Sterculia foetida kernel oil favored choosing as a feedstock. The Acid-catalyzed transesterification process is conducted for converting Sterculia foetida kernel oil into methyl ester. Experimental analysis was conducted using blends such as SFME20, SFME40, SFME60, SFME80, SFME100, and standard diesel at atmospheric conditions. The observations concluded that the Smoke opacity, Hydro carbon emissions, and carbon monoxide emissions lowered with increase in SFME content in diesel. In addition, the performance aspects namely BTE lowered with increase in SFME in diesel/SFME blends. Carbon-di-oxide and Nitroden oxide emissions increased when compared with standard diesel becausce of its higher O2 concentration. The combustion analysis witnessed a reduction in HRR and ICP for SFME-diesel blends relative to standard diesel.

A novel Near-Infrared rhodamine-derivated turn-on fluorescence probe for sensing SO32− detection and their bio-imaging in vitro and in vivo

Sulfur dioxide (SO2) is an important marker in the human body, and maintaining its balance is very significant for human health. The high concentration of SO2 will cause harm to human health because of the transient nature of SO2. To measure the level of SO2, it is urgent to find a suitable detection method for the real-time monitoring of sulfite. Herein, we designed and exploited a Near-Infrared (NIR) turn-on fluorescent probe L derived from rhodamine for the detection of SO32− in living cells and zebrafish. The addition of sulfite would attack the 4-position of the carbonyl group of levulinic acid, resulting in the cleavage of the ester bond and the formation of the fluorophore. The intramolecular charge transfer (ICT) was restored thus the monitoring system emitted the corresponding long NIR fluorescence at 646 nm. Probe L had high selectivity, a short response period within 10 min, and the detection limit of 0.6 μM. Besides, Probe L had a long excitation wavelength (>580 nm), which was in favor of more deeply biological imaging properties. Moreover, Probe L had low cell cytotoxicity through MTT assay, thus it was confirmed with good biocompatibility. In addition, probe L could successfully real-time monitor exogenous and endogenous sulfite in living cells, and be applied in zebrafish. The confocal results suggested that probe L had strong potential application prospect of outstanding capabilities for detecting sulfite in clinical diagnostics.

Effect of high levels of CO2 and O2 on membrane fatty acid profile and membrane physiology of meat spoilage bacteria

The membrane is the major protective barrier separating the cell from the environment and is thus important for bacteria to survive environmental stress. This study investigates changes in membrane lipid compositions and membrane physiology of meat spoiling bacteria in response to high CO2 (30%) and O2 (70%) concentrations, as commonly used for modified atmosphere packaging of meat. Therefore, the fatty acid profile as well as membrane fluidity, permeability and cell surface were determined and correlated to the genomic settings of five meat spoiling bacteria Brochothrix (B.) thermosphacta, Carnobacterium (C.) divergens, C. maltaromaticum, Leuconostoc (L.) gelidum subsp. gelidum and L. gelidum subsp. gasicomitatum cultivated under different gas atmospheres. We identified different genomic potentials for fatty acid adaptations, which were in accordance with actual measured changes in the fatty acid composition for each species in response to CO2 and/or O2, e.g., an increase in saturated, iso and cyclopropane fatty acids. Even though fatty acid changes were species-specific, the general physiological responses were similar, comprising a decreased membrane permeability and fluidity. Thus, we concluded that meat spoiling bacteria facilitate a change in membrane fatty acids upon exposure to O2 and CO2, what leads to alteration of membrane fluidity and permeability. The observed adaptations might contribute to the resistance of meat spoilers against detrimental effects of the gases O2 and CO2 and thus help to explain their ability to grow under different modified atmospheres. Furthermore, this study provides fundamental knowledge regarding the impact of fatty acid changes on important membrane properties of bacteria.

A comprehensive study on the oxidative pyrolysis of epoxy resin from fiber/epoxy composites: Product characteristics and kinetics

Thermal treatment has been the most feasible process to recycle valuable carbon fibers and obtain fuel and chemicals from waste fiber/epoxy composites. The present work studied the oxidative pyrolysis behaviors of epoxy resin from fiber/epoxy composites using a thermogravimetric apparatus and a fixed-bed reactor, respectively. The effects of various O2 concentrations on the thermal behaviors of epoxy resin were investigated and the product characteristics were analyzed. Furthermore, a multi distributed activation energy model (multi-DAEM) was first developed to determine the oxidative pyrolysis kinetics of epoxy resin under various atmospheres. Results showed that the degradation behaviors of epoxy resin were largely altered by the O2 concentrations. High O2 concentrations accelerated the primary decomposition of epoxy resin and shifted the oxidation of resin residue into lower temperatures. High contents of methylcyclohexene and phenolic derivatives were detected in liquid products. In air atmosphere, high yields of CO and CO2 were generated and distributed in several stages. The kinetic analysis indicated that the multi-DAEM method can well explain the oxidative pyrolysis behaviors of epoxy resin. A minimum six-reaction fitting process can perfectly simulate the oxidative pyrolysis of epoxy resin. The predictions for various O2 concentrations were in good agreement with the experimental tests.