Nitrous Oxide Is No Laughing Matter: A Historical Review of Nitrous Oxide Gas-Sensing Capabilities Highlighting the Need for Further Exploration

Temperature effects on nitrogen removal and N2O emissions in anammox reactors

Mainstream anammox faces challenges in adapting to non-optimal temperatures and managing greenhouse gas emissions. This study investigates nitrogen removal and N2O emissions in attached-growth anammox reactors subjected to rapid temperature shifts (15-55 °C). Temperature reductions to 15-25 °C had minimal impact on the anammox bacterial populations, with nitrogen removal rates of 0.37±0.11 gN/(L⋅d) and 0.88±0.10 gN/(L⋅d) at 15 °C and 25 °C, respectively. In contrast, increasing temperatures to 45-55 °C significantly diminished both anammox biomass and bioactivity. The reactor at 35 °C exhibited the lowest N2O emissions (< 1.0 mgN/(L⋅d)), while emissions rose to approximately 5.0 mgN/(L⋅d) at 15 °C and 3.4 mgN/(L⋅d) at 55 °C (during 295-395 d), primarily due to denitrification performed by coexisting ammonia-oxidizing bacteria and denitrifying microbes. This study provides insights into temperature adaptability and N2O emission risks, supporting mainstream anammox applications.

Potential of enhanced efficiency nitrogen fertilizers in reducing nitrogen and carbon losses in a sandy soil integrated crop-livestock system

The demand for food is increasing, which poses significant challenges to humanity's sustainable and sufficient food production. Using fertilizers with new technologies with a low environmental impact is becoming increasingly necessary. In this context, the industry has been creating alternatives to optimize the use of nitrogen (N) fertilizers, with the improvement of urea being crucial for sustainable agricultural production. The objective of this study was to assess the use of fertilizers with integrated technology, specifically urea NBPT + Duromide and formaldehyde urea, aiming to reduce N losses through ammonia (NH3-N) volatilization and, consequently, mitigate carbon dioxide (CO2) emissions in the integrated crop-livestock system (ICLS), thereby addressing the impacts of global warming. Evaluations were conducted over three agricultural years (2020/2021, 2021/2022, and 2022/2023). The pasture used was Urochloa Brizhanta cv. marandu, and soybeans (Glycine max L) were cultivated. The experimental design was a randomized complete block with four replications in a 3 × 4 factorial arrangement. The treatments consisted of three N sources: conventional urea (UrConv) for immediate release, formaldehyde urea (UrFormaldehyde) for slow release, and urea with urease inhibitor and Duromide technology (UrDuromide), combined with four rates (0, 100, 200, and 400 kg ha-1 of N). NH3-N volatilization data were subjected to nonlinear regression using a logistic model. NH3-N volatilization losses varied according to the rate and fertilizer, reaching up to 33% in UrConv. UrDuromide exhibited reduced efficiency over the evaluated years compared to UrConv, reducing losses by 52% in the first year, 46% in the second, and only 5% in the third. UrFormaldehyde showed less variability, ranging between 57% and 45% reduction in NH3-N losses. The effects on TOC and CO2 emissions followed similar trends, with UrConv causing the highest CO2 emissions and more significant TOC accumulation. UrFormaldehyde reduced CO2 by up to 8% compared to UrConv, while UrDuromide reduced it by 6% compared to UrConv in greenhouse gas emissions and consequently lower soil organic carbon accumulation. In conclusion, using technology to enhance efficiency in nitrogen fertilizers showed promising results in reducing greenhouse gas emissions, offering hope for a sustainable future and making it a viable alternative to conventional urea sources.

2D MXenes and their composites; design, synthesis, and environmental sensing applications

Novel 2D layered MXene materials were first reported in 2011 at Drexel University. MXenes are widely used in multidisciplinary applications due to their anomalous electrical conductivity, high surface area, and chemical, mechanical, and physical properties. This review summarises MXene synthesis and applications in environmental sensing. The first section describes different methods for MXene synthesis, including fluorinated and non-fluorinated methods. MXene's layered structure, surface terminal groups, and the space between layers significantly impact its properties. Different methods to separate different MXene layers are also discussed using various intercalation reagents and commercially synthesized MXene without compromising the environment. This review also explains the effect of MXene's surface functionalization on its characteristics. The second section of the review describes gas and pesticide sensing applications of Mxenes and its composites. Its good conductivity, surface functionalization with negatively charged groups, intrinsic chemical nature, and good mechanical stability make it a prominent material for room temperature sensing of environmental samples, such as polar and nonpolar gases, volatile organic compounds, and pesticides. This review will enhance the young scientists' knowledge of MXene-based materials and stimulate their diversity and hybrid conformation in environmental sensing applications.

Discriminative Analysis of NOx Gases by Two-Dimensional Violet Phosphorus Field-Effect Transistors

Two-dimensional violet phosphorus (VP) has emerged as a new sensing material in various sensing applications due to its unique electrical properties and high stability among allotropes of phosphorus. Currently, the research of the VP-based analysis method is at the early stage. In this work, a VP nanosheet-based field-effect transistor (FET) sensor is reported for the detection of NO2 and N2O gases with extraordinary sensing performance. This sensor can achieve excellent sensitivity of up to ∼50% current change/ppm and a low detection limit of 5.9 ppb and enables the NO2 analysis in various mixed gases. Moreover, this sensor can effectively distinguish between NO2 and N2O gases, which is a big challenge for current FET or chemiresistor gas sensors. The different sensing behaviors of the VP sensor to NO2 and N2O gases have been investigated, and the mechanism study shows that the adsorption energy, bond length of the gas molecule on the VP surface, and the decomposition of N2O led to the differential responses. This work is one of the pioneer studies of VP gas sensors and presents a new sensing method for the discriminative analysis of NO2 and N2O for greenhouse gas emission monitoring and air quality control.

Wearable Nano-Based Gas Sensors for Environmental Monitoring and Encountered Challenges in Optimization

With a rising emphasis on public safety and quality of life, there is an urgent need to ensure optimal air quality, both indoors and outdoors. Detecting toxic gaseous compounds plays a pivotal role in shaping our sustainable future. This review aims to elucidate the advancements in smart wearable (nano)sensors for monitoring harmful gaseous pollutants, such as ammonia (NH3), nitric oxide (NO), nitrous oxide (N2O), nitrogen dioxide (NO2), carbon monoxide (CO), carbon dioxide (CO2), hydrogen sulfide (H2S), sulfur dioxide (SO2), ozone (O3), hydrocarbons (CxHy), and hydrogen fluoride (HF). Differentiating this review from its predecessors, we shed light on the challenges faced in enhancing sensor performance and offer a deep dive into the evolution of sensing materials, wearable substrates, electrodes, and types of sensors. Noteworthy materials for robust detection systems encompass 2D nanostructures, carbon nanomaterials, conducting polymers, nanohybrids, and metal oxide semiconductors. A dedicated section dissects the significance of circuit integration, miniaturization, real-time sensing, repeatability, reusability, power efficiency, gas-sensitive material deposition, selectivity, sensitivity, stability, and response/recovery time, pinpointing gaps in the current knowledge and offering avenues for further research. To conclude, we provide insights and suggestions for the prospective trajectory of smart wearable nanosensors in addressing the extant challenges.