Ultra-Flexible, Breathable, and Robust PAN/MWCNTs/PANI Nanofiber Networks for High-Performance Wearable Gas Sensor Application.

Wearable gas sensors have drawn great attention for potential applications in health monitoring, minienvironment detection, and advanced soft electronic noses. However, it still remains a great challenge to simultaneously achieve excellent flexibility, high sensitivity, robustness, and gas permeability, because of the inherent limitation of widely used traditional organic flexible substrates. Herein, an electrospinning polyacrylonitrile (PAN) nanofiber network was designed as a flexible substrate, on which an ultraflexible wearable gas sensor was prepared with in situ assembled polyaniline (PANI) and multiwalled carbon nanotubes (MWCNTs) as a sensitive layer. The unique nanofiber network and strong binding force between substrate and sensing materials endow the wearable gas sensor with excellent robustness, flexibility, and gas permeability. The wearable sensor can maintain stable NH3 sensing performance while sustaining extreme bending and stretching (50% of strain). The Young's modulus of wearable PAN/MWCNTs/PANI sensor is as low as 18.9 MPa, which is several orders of magnitude smaller than those of reported flexible sensors. The water vapor transmission rate of the sensor is 0.38 g/(cm2 24 h), which enables the wearing comfort of the sensor. Most importantly, due to the effective exposure of sensing sites as well as the heterostructure effect between MWCNTs and PANI, the sensor shows high sensitivity to NH3 at room temperature, and the theoretical limit of detection is as low as 300 ppb. This work provides a new avenue for the realization of reliable and high-performance wearable gas sensors.

Si, O-Codoped Carbonized Polymer Dots with High Chemiresistive Gas Sensing Performance at Room Temperature.

A new type of carbonized polymer dot was prepared by the one-step hydrothermal method of triethoxylsilane (TEOS) and citric acid (CA). The sensor made from carbonized polymer dots (CPDs) showed superior gas sensing performance toward ammonia at room temperature. The Si, O-codoped CPDs exhibited superior ammonia sensing performance at room temperature, including a low practical limit of detection (pLOD) of 1 ppm (Ra/Rg: 1.10, 1 ppm), short response/recovery time (30/36 s, 1 ppm), high humidity resistance (less than 5% undulation when changing relative humidity to 80 from 30%), high stability (less than 5% initial response undulation after 120 days), reliable repeatability, and high selectivity against other interferential gases. The gas sensing mechanism was investigated through control experiments and in situ FTIR, indicating that Si, O-codoping essentially improves the electron transfer capability of CPDs and synergistically dominates the superior ammonia sensing properties of the CPDs. This work presents a facile strategy for constructing novel high-performance, single-component carbonized polymer dots for gas sensing.

Key factors affecting NH3-N in the Huaihe River Basin due to human activities.

Human activity factors have a significant impact on changes in ammonia nitrogen (NH3-N) content in rivers. Existing research mainly focuses on human activity factors as type factors, and lacks research on the key factors affecting river NH3-N among human activity factors. Therefore, this paper aims to study the key factors affecting human activities on NH3-N in the Huaihe River through various statistical analysis methods. The study found that changes in NH3-N content in the Huaihe River are mainly affected by land use patterns in the basin. There are two different ways in which land use affects NH3-N in rivers: direct effects and indirect effects. We also studied the main pathways through which changes in key factors in human activities affect NH3-N in the Huaihe River by constructing a structural equation model. The results showed that crop sowing area and afforestation area have a significant direct effect on NH3-N in the Huaihe River. In addition, crop sowing area and afforestation area can also affect river NH3-N by regulating the amount of nitrogen fertilizer and human excrement. This study is of great significance for understanding how human activities regulate NH3-N content in rivers.

[Effects of water-nitrogen interactions on NH3 and N2O emissions and yield in winter wheat cropland]. / 水氮互作对冬小麦农田NH3和N2O排放及产量的影响.

To investigate the effects of different irrigation and nitrogen application modes on nitrogen gaseous loss in winter wheat farmland, we conducted a field experiment at Changqing Irrigation Experiment Station in Shandong Province, with two irrigation levels (80%-90% θf(I1) and 70%-80% θf(I2)) and three nitrogen application levels (conventional nitrogen application of 240 kg·hm-2(N1), nitrogen reduction of 12.5% (N2), and nitrogen reduction of 25% (N3)). The results showed that ammonia volatilization and nitrous oxide emission rate peak appeared within 2-4 days after fertilization or irrigation. The ammonia volatilization rate during the chasing fertilizer period was significantly higher than that during the basal fertilizer period. Compared with other treatments, the ave-rage ammonia volatilization rate of I2N2 treatment during the chasing fertilizer period was reduced by 10.1%-51.6%, and the average nitrous oxide emission rate over the whole growth period was reduced by 15.4%-52.2%. The ammonia volatilization rate was significantly positively associated with surface soil pH value and ammonium nitrogen content, while the nitrous oxide emission rate was significantly positively associated with nitrate content in topsoil. The accumulation amount of soil ammonia volatilization and nitrous oxide emission ranged from 0.83-1.42 and 0.11-0.33 kg·hm-2, respectively. Moderate reduction of irrigation water and nitrogen input could effectively reduce cumulative amounts of ammonia volatilization and nitrous oxide emission from winter wheat farmland. The cumulative amounts of ammonia volatilization and nitrous oxide emission under I1N3 and I2N2 treatments were signi-ficantly lower than those under other treatments. The highest winter wheat yield (5615.6 kg·hm-2) appeared in I2N2 treatment. The irrigation water utilization efficiency of I2 was significantly higher than that of I1, with the maximum increase rate of 45.2%. Compared with N1 and N3 treatments, the maximum increase rate of nitrogen fertilizer productivity and agricultural utilization efficiency in N2 reached 15.2% and 31.8%, respectively. In conclusion, the treatment with 70%-80% θf irrigation level and 210 kg·hm-2 nitrogen input could effectively improve the utilization efficiency of irrigation water and nitrogen fertilization and reduce gaseous loss from winter wheat farmland.

Hybrid MoSe2/P3HT Transistor for Real-Time Ammonia Sensing in Biofluids.

Organic and inorganic hybrid field-effect transistors (FETs), utilizing layered molybdenum diselenide (MoSe2) and an organic semiconductor poly(3-hexylthiophene) (P3HT), are presented for biosensing applications. A new hybrid device structure that combines organic (P3HT) and inorganic (MoSe2) components is showcased for accurate and selective bioanalyte detection in human bodily fluids to overcome 2D-transition metal dichalcogenides (TMDs) nonspecific interactions. This hybrid structure utilizes organic and inorganic semiconductors' high surface-to-volume ratio, carrier transport, and conductivity for biosensing. Ammonia concentrations in saliva and plasma are closely linked to physiological and pathological conditions of the human body. A highly sensitive hybrid FET biosensor detects total ammonia (NH4+ and NH3) from 0.5 µM to 1 mM concentrations, with a detection limit of 0.65 µM in human bodily fluids. The sensor's ammonia specificity in artificial saliva against interfering species is showcased. Furthermore, the fabricated hybrid FET device exhibits a stable and repeatable response to ammonia in both saliva and plasma, achieving a remarkable response level of 2300 at a 1 mM concentration of ammonia, surpassing existing literature by 10-fold. This hybrid FET biosensing platform holds significant promise for developing a precise tool for the real-time monitoring of ammonia concentrations in human biological fluids, offering potential applications in point-of-care diagnostics.

Measuring the Release of Ammonia from Leaves.

Ammonia (NH3) is released from the leaves to the atmosphere when atmospheric NH3 concentration is low; in contrast, when atmospheric NH3 concentration is high, NH3 in the atmosphere is absorbed by the leaves. Some previous studies have examined relationships of such NH3 gas exchange with photorespiration, because a NH3 production reaction is involved in the photorespiratory pathway. NH3 compensation point (χNH3) is known as a parameter that represents an NH3 emission potential of the leaves. Two main procedures for determining the χNH3: "gas exchange method" and "apoplast extraction method" are explained in this chapter.

Significantly underestimated traffic-related ammonia emissions in Chinese megacities: Evidence from satellite observations during COVID-19 lockdowns.

Ammonia (NH3) plays an important role in the formation of atmospheric particulate matter, but the contribution of traffic-related emissions remains unclear, particularly in megacities with a large number of vehicles. Taking the opportunity of the stringent COVID-19 lockdowns implemented in Beijing and Shanghai in 2022, this study aims to estimate the traffic-related NH3 emissions in these two megacities based on satellite observations. Differences between urban and suburban areas during the lockdown and non-lockdown periods are compared. It was found that despite different dominating sources, the overall NH3 concentrations in urban and suburban areas were at a similar level, and the lockdown resulted in a more prominent decrease in urban areas, where traffic activities were most heavily affected. The traffic-related contribution to the total emission was estimated to be ∼30% in megacities, and ∼40% in urban areas, which are about 2-10 times higher than that in previous studies. The findings indicate that the traffic-related NH3 emissions have been significantly underestimated in previous studies and may play a more critical role in the formation of air pollution in megacities, especially in winter, when agricultural emissions are relatively low. This study highlights the importance of traffic-related NH3 emissions in Chinese megacities and the need to reassess the emissions and their impacts on air quality.

Dose-dependent effects of sodium dodecyl sulfate and hydrogen peroxide treatments on methane emission from pig manure during storage.

Mitigation of methane (CH4) emissions from slurry pits within pig barns can be achieved through treatment of residual slurry left after frequent flushing of the slurry pits. In this study, dosages of additives such as sodium dodecyl sulfate (SDS) and hydrogen peroxide (H2O2) were optimized to achieve reduction in CH4 emissions from residual pig slurry during storage. In addition, the effects on emissions when both the treatments were combined and the effects of SDS treatment on slurry acidified with sulfuric acid (H2SO4) were studied in order to reduce CH4 and ammonia (NH3) emissions from residual pig slurry storage. A maximum of 98% and 70% reduction in CH4 emissions were achieved with SDS and H2O2 treatments, respectively. The combination of SDS and H2O2 did not increase efficiency in reducing CH4 emissions compared to SDS treatment alone. Whereas the application of SDS to slurry acidified with H2SO4 (pH 6.2) increased the CH4 mitigation efficiency by 15-30% compared to treating slurry with only SDS. The combined treatment (SDS + H2SO4) reduced NH3 emissions by 20% compared to treating slurry with H2SO4 (pH 6.2) alone. Hereby, combined treatment (SDS + H2SO4) can reduce both CH4 and NH3 emissions, with a reduced amount of chemicals required for the treatment. Hence, application of SDS at concentrations <2 g kg-1 to acidified slurry is recommended to treat residual pig manure in pig barns.

Investigation of pollutants accumulation in the submerged zone for pyrite-based bioretention facilities under continuous rainfall events.

Submerged zone in bioretention facilities for stormwater treatment has been approved to be an effective structure amendment to improve denitrification capability. However, the role and influence of water quality changes in the submerged zone under natural continuous random rainfall patterns are still not clear, especially when the rainfall is less than the pore water in the submerged zone. In this study, continuous rainfall events with different rainfall volume (light rain-light rain-heavy rain) were designed in a lab-scale woodchip mulched pyrite bioretention facility to test the effects of rainfall pattern. The results exhibited that light rain events significantly affected the pollutant removal performance of bioretention for the next rainfall. Different effects were observed during the long-term operation. In the 5th month, light rain reduced the ammonia removal efficiency of subsequent rainstorm events by 8.70%, while in the 12th month, when nitrate leakage occurred, light rain led to a 40.24% reduction in the next heavy rain event's nitrate removal efficiency. Additionally, light rain would also affect the concentration of by-products in the next rainfall. Following a light rain, the concentration of sulfate in the subsequent light rainfall can increase by 24.4 mg/L, and by 11.92 mg/L in a heavy rain. The water quality in the submerged zone and media characteristics analysis suggested that nitrogen conversion capacity of the substrate and microbes, such as Nitrospira (2.86%) and Thiobacillus (35.71%), as well as the in-situ accumulation of pollutants under light rain played important roles. This study clarifies the relationship between successive rainfall events and provides a more comprehensive understanding of bioretention facilities. This is beneficial for field study of bioretention facilities in the face of complex rainfall events.

Development of a Sensitive Colorimetric Indicator for Detecting Beef Spoilage in Smart Packaging.

This study aimed to fabricate and characterize a novel colorimetric indicator designed to detect ammonia (NH3) and monitor meat freshness. The sensing platform was constructed using electrospun nanofibers made from polylactic acid (PLA), which were then impregnated with anthocyanins as a natural pH-sensitive dye, extracted from red cabbage. This research involved investigating the relationship between the various concentrations of anthocyanins and the colorimetric platform's efficiency when exposed to ammonia vapor. Scanning electron microscope (SEM) results were used to examine the morphology and structure of the nanofiber mats before and after the dip-coating process. The study also delved into the selectivity of the indicator when exposed to various volatile organic compounds (VOCs) and their stability under extreme humidity levels. Furthermore, the platform's sensitivity was evaluated as it encountered ammonia (NH3) in concentrations ranging from 1 to 100 ppm, with varying dye concentrations. The developed indicator demonstrated an exceptional detection limit of 1 ppm of MH3 within just 30 min, making it highly sensitive to subtle changes in gas concentration. The indicator proved effective in assessing meat freshness by detecting spoilage levels in beef over time. It reliably identified spoilage after 10 h and 7 days, corresponding to bacterial growth thresholds (107 CFU/mL), both at room temperature and in refrigerated environments, respectively. With its simple visual detection mechanism, the platform offered a straightforward and user-friendly solution for consumers and industry professionals alike to monitor packaged beef freshness, enhancing food safety and quality assurance.

A critical review on characterization, human health risk assessment and mitigation of malodorous gaseous emission during the composting process.

Composting has emerged as a suitable method to convert or transform organic waste including manure, green waste, and food waste into valuable products with several advantages, such as high efficiency, cost feasibility, and being environmentally friendly. However, volatile organic compounds (VOCs), mainly malodorous gases, are the major concern and challenges to overcome in facilitating composting. Ammonia (NH3) and volatile sulfur compounds (VSCs), including hydrogen sulfide (H2S), and methyl mercaptan (CH4S), primarily contributed to the malodorous gases emission during the entire composting process due to their low olfactory threshold. These compounds are mainly emitted at the thermophilic phase, accounting for over 70% of total gas emissions during the whole process, whereas methane (CH4) and nitrous oxide (N2O) are commonly detected during the mesophilic and cooling phases. Therefore, the human health risk assessment of malodorous gases using various indexes such as ECi (maximum exposure concentration for an individual volatile compound EC), HR (non-carcinogenic risk), and CR (carcinogenic risk) has been evaluated and discussed. Also, several strategies such as maintaining optimal operating conditions, and adding bulking agents and additives (e.g., biochar and zeolite) to reduce malodorous emissions have been pointed out and highlighted. Biochar has specific adsorption properties such as high surface area and high porosity and contains various functional groups that can adsorb up to 60%-70% of malodorous gases emitted from composting. Notably, biofiltration emerged as a resilient and cost-effective technique, achieving up to 90% reduction in malodorous gases at the end-of-pipe. This study offers a comprehensive insight into the characterization of malodorous emissions during composting. Additionally, it emphasizes the need to address these issues on a larger scale and provides a promising outlook for future research.

Revealing mechanisms of NH3 and N2O emissions reduction in the rapid bio-drying of food waste: Insights from organic nitrogen composition and microbial activity.

Inevitably, aerobic biological treatment processes generate emissions of ammonia (NH3) and greenhouse gas (GHGs) emissions, especially nitrous oxide (N2O). The rapid bio-drying process (RBD) for food waste (FW) alleviates issues arising from its substantial growth. However, its emissions of NH3 and N2O remain unknown, and the correlation with nitrogen components in the substrate remains unclear, significantly impeding its widespread adoption. Here, the nitrogen loss and its mechanisms in RBD were investigated, and the results are as follows: The total emission of NH3 and N2O were1.42 and 1.16 mg/kg FW (fresh weight), respectively, achieving a 98 % reduction compared to prior studies. Structural equation modeling demonstrates that acid ammonium nitrogen (AN) decomposition chiefly generates NH3 in compost (p < 0.001). Strong correlation (p < 0.001) exists between amino acid nitrogen (AAN) and AN. In-depth analysis of microbial succession during the process reveals that the enrichment of Brevibacterium, Corynebacterium, Dietzia, Fastidiosipila, Lactobacillus, Mycobacterium, Peptoniphilus, and Truepera, are conducive to reducing the accumulation of AN and AAN in the substrate, minimizing NH3 emissions (p < 0.05). While Pseudomonas, Denitrobacterium, Nitrospira, and Bacillus are identified as key species contributing to N2O emissions during the process. Correlation analysis between physicochemical conditions and microbial succession in the system indicates that the moisture content and NO3- levels during the composting process provide suitable conditions for the growth of bacteria that contribute to NH3 and N2O emissions reduction, these enrichment in RBD process minimizing NH3 and N2O emissions. This study can offer crucial theoretical and data support for the resource utilization process of perishable organic solid waste, mitigating NH3 and GHGs emissions.

An ammonia-sensitive fluorescence sensor based on polyvinyl alcohol-graphene quantum dots/halloysite nanotubes hybrid film for monitoring fish freshness.

A fluorescent hybrid film composed of nitrogen-doped graphene quantum dots (N-GQDs) loaded on halloysite nanotubes (HNTs) (N-GQDs/HNTs nanocomposite) as a sensitive element and polyvinyl alcohol (PVA) as a film-forming matrix was designed for freshness detection. The PVA-N-GQDs/HNTs hybrid film exhibited significantly enhanced fluorescence attributed to the loading of N-GQDs onto the surface of HNTs through electrostatic interactions and hydrogen bonding, effectively reducing their aggregation. The fluorescence of the hybrid film could be quenched by ammonia via photoinduced electron transfer (PET), with good linearity in the range of 20 ppm to 500 ppm ammonia and a limit of detection (LOD) of 0.63 ppm. In addition, the hybrid film was applied to monitor the freshness of seawater fish and freshwater fish stored at refrigeration and room temperature to evaluate the practicality of this approach. The developed hybrid film showed promise for nondestructive and on-site monitoring of fish spoilage.

Sources and processes affecting the abundances of atmospheric NHx using δ15N over northwestern Indo-Gangetic plain.

Ammonia (NH3) is the major constituent among all the reactive nitrogen species present in the atmosphere, and the most essential species for secondary inorganic aerosol formation. Recent satellite-based observations have identified the Indo-Gangetic Plain (IGP) as a major hotspot of global NH3 emission; however, the major sources and atmospheric processes affecting its abundance are poorly understood. The present study aims to understand the wintertime sources of NH3 over a semi-urban site (Patiala, 30.3°N, 76.4°E, 249 m amsl) located in the IGP using species specific δ15N in PM2.5. A distinct diurnal variation in the stable isotopic signature of total nitrogen (δ15N-TN) and ammonium (δ15N-NH4+) were observed; although, average day and night time concentrations of TN and NH4+ were similar. Mixing model results using δ15N-NH3 reveal the dominance of non-agricultural emissions (NH3 slip: 47 ± 24%) over agricultural emissions (24 ± 11%), combustion sources (19 ± 14 %), and biomass burning (10 ± 8%) for atmospheric NH3. Diurnal variability in source contributions to NH3 was insignificant. Further, significantly negative correlations of δ15N-NH4+ with ambient relative humidity (RH) and daytime NO3--N concentration were observed, and attributed to the possibility of NH4NO3 volatilization during day-time owing to lower RH and higher temperature, resulting in isotopic enrichment of the remaining NH4+ in aerosol phase. This study, a first of its type from India, highlights the importance of non-agricultural NH3 emissions over the agriculture dominated IGP region, and the role of local meteorology on the isotopic fractionation of δ15N in aerosol NH4+.

A hydrogel-modified electrochemical biosensor for the rapid detection of ammonia­nitrogen-resistant bacteria.

Ammonia­nitrogen wastewater is one of the main pollutants in the current environment. Rapid detection of microorganisms resistant to ammonia­nitrogen provides a basis for bioremediation of ammonia­nitrogen contaminated sites. This study uses electrochemical analysis for efficiently detecting of ammonia-resistant bacteria, utilizing a commercially available, low-cost screen-printed electrode (SPE) modified with agarose-based hydrogel (gel) or graphene oxide (GO). At the same time, the study employed electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) to monitor bacterial growth, revealing Escherichia coli (E. coli) inhibition upon ammonia­nitrogen addition, while Raoultella terrigena (RN1) and Pseudomonas (RN2) exhibit tolerance. The method provides sensitivity results in <45 min, which is significantly faster than traditional methods. RN1 and RN2 exhibit promising ammonia­nitrogen removal rates, reaching up to 81 % and 92 %, respectively. This study aimed to develop an effective electrochemical method for rapidly detecting the sensitivity of microorganisms to ammonia­nitrogen. The method offers advantages such as high speed, efficiency, and cost-effectiveness, potentially providing valuable microbial resources for mitigating ammonia nitrogen wastewater pollution.

Impacts assessment of nitrification inhibitors on U.S. agricultural emissions of reactive nitrogen gases.

Fertilizer-intensive agriculture leads to emissions of reactive nitrogen (Nr), posing threats to climate via nitrous oxide (N2O) and to air quality and human health via nitric oxide (NO) and ammonia (NH3) that form ozone and particulate matter (PM) downwind. Adding nitrification inhibitors (NIs) to fertilizers can mitigate N2O and NO emissions but may stimulate NH3 emissions. Quantifying the net effects of these trade-offs requires spatially resolving changes in emissions and associated impacts. We introduce an assessment framework to quantify such trade-off effects. It deploys an agroecosystem model with enhanced capabilities to predict emissions of Nr with or without the use of NIs, and a social cost of greenhouse gas to monetize the impacts of N2O on climate. The framework also incorporates reduced-complexity air quality and health models to monetize associated impacts of NO and NH3 emissions on human health downwind via ozone and PM. Evaluation of our model against available field measurements showed that it captured the direction of emission changes but underestimated reductions in N2O and overestimated increases in NH3 emissions. The model estimated that, averaged over applicable U.S. agricultural soils, NIs could reduce N2O and NO emissions by an average of 11% and 16%, respectively, while stimulating NH3 emissions by 87%. Impacts are largest in regions with moderate soil temperatures and occur mostly within two to three months of N fertilizer and NI application. An alternative estimate of NI-induced emission changes was obtained by multiplying the baseline emissions from the agroecosystem model by the reported relative changes in Nr emissions suggested from a global meta-analysis: -44% for N2O, -24% for NO and +20% for NH3. Monetized assessments indicate that on an annual scale, NI-induced harms from increased NH3 emissions outweigh (8.5-33.8 times) the benefits of reducing NO and N2O emissions in all agricultural regions, according to model-based estimates. Even under meta-analysis-based estimates, NI-induced damages exceed benefits by a factor of 1.1-4. Our study highlights the importance of considering multiple pollutants when assessing NIs, and underscores the need to mitigate NH3 emissions. Further field studies are needed to evaluate the robustness of multi-pollutant assessments.

The dynamics of nitrous oxide and methane emissions from various types of dairy manure at smallholder dairy farms as affected by storage periods.

Storing manure emits greenhouse gas (GHG) emissions, including nitrous oxide (N2O) and methane (CH4). However, the emissions from types of manure stored at smallholder dairy farms remains unknown. Hence, the study aims to analyse the dynamics of N2O and CH4 from different types of dairy manure as affected by storage periods. We collected samples from fresh manure (FM-DF1), manure from communal ponds in an urban dairy farm (IP-DF1, FP-DF1, MS-DF1), fresh manure from an urban dairy farm (FM-DF2), and fresh (FM-DF3), separated (FS-DF3), and fermented manure (FR-DF3) from a peri-urban dairy farm, and stored them for eight weeks and analyse them using the closed chamber method. The changes of manure composition including total solids (TS), nitrogen (N), ammonia-nitrogen (N-NH3), and carbon (C) were analysed. Results indicated an increase TS in all treatments except for MS-DF1, while N, N-NH3, and C content decreased in all treatments. The N2O emissions formed at the start, peaked in the middle, and declined towards the end storage period. The CH4 emissions peaked at the start and decreased until the end storage period. Treatment FM-DF2 yield highest cumulative of N2O (0.82 g/m2) and CH4 (41.63 g/m2) compared to other fresh manure treatment. A mixed model analysis detected a significant interaction (p < 0.05) between manure types and storage periods. In conclusion, manure types and storage periods affect the emissions. Changes in manure concentration during storage and animal diets are two important factors influencing emissions. Strategies to reduce emissions include reducing moisture content in manure, shortening storage periods, and improving feed quality.

Developing a Chemiresistive Gas Sensor Array for Simultaneous Detection of Ammonia and Carbon Dioxide Gases.

Chemiresistive polymer-based sensors are promising platforms for monitoring various gases and volatile organic compounds. While they offer appealing attributes, such as ease of fabrication, flexibility, and cost-effectiveness, most of these sensors have a nearly identical response to cross-reactive gases, such as ammonia (NH3) and carbon dioxide (CO2). Aiming to address the shortcomings of chemiresistive polymer-based sensors in selectivity and simultaneous measurements of cross-reactive gases, a chemiresistive sensor array was developed consisting of components sensitive to carbon dioxide and ammonia as well as a control segment to provide the baseline. The designed system demonstrated a wide detection range for both ammonia (ranging from 0.05 to 1000 ppm) and carbon dioxide (ranging from 103 to 106 ppm) at both room and low temperatures (e.g., 4 °C). Our results also demonstrate the ability of this sensor array for the simultaneous detection of carbon dioxide and ammonia selectively in the presence of other gases and volatile organic compounds. Finally, the array was used to monitor CO2/NH3 in real food samples to demonstrate the potential for real-world applications.

Ammonia Detection by Electronic Noses for a Safer Work Environment.

Providing employees with proper work conditions should be one of the main concerns of any employer. Even so, in many cases, work shifts chronically expose the workers to a wide range of potentially harmful compounds, such as ammonia. Ammonia has been present in the composition of products commonly used in a wide range of industries, namely production in lines, and also laboratories, schools, hospitals, and others. Chronic exposure to ammonia can yield several diseases, such as irritation and pruritus, as well as inflammation of ocular, cutaneous, and respiratory tissues. In more extreme cases, exposure to ammonia is also related to dyspnea, progressive cyanosis, and pulmonary edema. As such, the use of ammonia needs to be properly regulated and monitored to ensure safer work environments. The Occupational Safety and Health Administration and the European Agency for Safety and Health at Work have already commissioned regulations on the acceptable limits of exposure to ammonia. Nevertheless, the monitoring of ammonia gas is still not normalized because appropriate sensors can be difficult to find as commercially available products. To help promote promising methods of developing ammonia sensors, this work will compile and compare the results published so far.

Effect of residual methane emission on physiological characteristics and carcass performance in Japanese Black cattle.

This study investigated the physiological characteristics and carcass performance associated with residual methane emissions (RME), and the effects of bull differences on CH4-related traits in Japanese Black cattle. Enteric methane (CH4) emissions from 156 Japanese Black cattle (111 heifers and 45 steers) were measured during early fattening using the sniffer method. Various physiological parameters were investigated to clarify the physiological traits between the high, middle, and low RME groups. CH4-related traits were examined to determine whether bull differences affected progeny CH4 emissions. Ruminal butyrate and NH3 concentrations were significantly higher in the high-RME group than in the low-RME group, whereas the propionate content was significantly higher in the low-RME group. Blood urea nitrogen, ß-hydroxybutyric acid, and insulin concentrations were significantly higher, and blood amino acids were lower in the high-RME group than in the other groups. No significant differences were observed in the carcass traits and beef fat composition between RME groups. CH4-related traits were significantly different among bull herds. Our results show that CH4-related traits are heritable, wherein bull differences affect progeny CH4 production capability, and that the above-mentioned rumen fermentations and blood metabolites could be used to evaluate enteric methanogenesis in Japanese Black cattle.