Organic Materials Research Articles

A prediction of high temperature magnetic coupling in transition metal phthalocyanines.

In spintronics, a perennial goal has been the generation of organic spin-bearing semiconductor materials with magnetic ordering stable at room temperature. To this end, the class of transition metal phthalocyanines has shown much promise in fulfilling this ambition. In particular, alpha-phase cobalt (II) phthalocyanine (α-CoPc) exhibits strong antiferromagnetic exchange interactions producing a long range order up to ∼100K. However, the underlying mechanism by which this magnetic interaction proceeds is not well understood. In this report, a simple mechanism has been proposed based on the Hubbard Hamiltonian, which elucidates the exchange coupling in α-CoPc. The mechanism provides stipulations for increasing the magnetic coupling, and this directs to a proposal that substitution of the central cobalt ion for rhodium will lead to a significant increase in coupling strength. The strength of this exchange interaction has been evaluated using broken symmetry hybrid exchange density functional theory and indicates that the novel rhodium (II) phthalocyanine system is indeed predicted to exhibit significantly stronger magnetic ordering. This study, therefore, identifies the coupling mechanism in α-CoPc as primarily attributable to kinetic exchange, explains its previously reported strong coupling relative to its first-row transition metal counterparts, and suggests that rhodium (II) phthalocyanine is likely to exhibit stable magnetic ordering at room temperature.

Publisher Correction: Non-classical crystallization in soft and organic materials

Publisher Correction: Non-classical crystallization in soft and organic materials

A Clean You Can Trust: Using an Evidence-Based Bundle to Transform Point-of-Use Treatment for Reusable Medical Devices at a Military Treatment Facility

ABSTRACT Introduction Throughout surgical and invasive procedures, reusable instruments and flexible endoscopes become soiled with organic and inorganic materials. When these substances are permitted to dry, a matrix of microbial cells, called biofilm, forms on the surface of devices, irreversibly binding and subsequently impeding the disinfection and sterilization process. To prevent biofilm formation from occurring, devices must be continuously flushed and wiped with water throughout the procedure and at the end of the case. This process, known as point-of-use treatment (POUT), is the critical first step in the decontamination of medical devices. Poor compliance with POUT can increase patient morbidity and mortality and result in failing hospital accreditation. Materials and Methods An interdisciplinary team used the Plan-Do-Study-Act (PDSA) to develop and implement an audit assessing 29 evidence-based criteria for POUT treatment. Each PDSA cycle supported evidence-based opportunities addressing feedback, workflow analysis, policy development, competency assessment creation, training module development, and infection prevention grand rounds. Four audits were performed over ten months to achieve improved organizational POUT compliance. Results Implementing recurrent PDSA cycles that included audits with feedback led to an evidence-based bundle of policies, competencies, and training for 34 different clinical areas. These interventions resulted in a 26% compliance increase (66% to 92%). Program-specific improvements included flexible endoscopes (+4%) and reusable instruments (+20%). Conclusions Multimodal evidence-based initiatives to improve compliance with workflow processes is a translatable POUT evidence-based practice project for similar Defense Health Agengy facilities. Workflow processes can be vetted and distributed using interdisciplinary teams to ensure viability, sustainability, and conformity with organizational requirements, resulting in a more ready force.

Enhancing prediction of elemental composition through machine learning decision tree models for biomass gasification optimization

Abstract The worldwide transition to cleaner, sustainable energy sources, prompted by population growth and industrialization, responds to uncertain fossil fuel prices and environmental concerns, highlighting the substantial benefits of renewable energy in reducing greenhouse gas emissions and addressing climate change. Derived from non-fossilized organic materials, biomass emerges as a significant and sustainable contributor to renewable energy. Its diverse nature is complemented by a range of conversion technologies, encompassing combustion, pyrolysis, gasification, and liquefaction, providing versatile avenues for biomass energy transformation. Gasification, the transformative process of converting organic matter into combustible gases under controlled oxygen levels, is accomplished through direct oxygen supply or pyrolysis. This method yields a dependable gaseous fuel versatile for heating, industrial processes, power generation, and liquid fuel production. Machine learning employs advanced statistical techniques for modeling across diverse industries, showcasing particular efficacy in optimizing thermochemical processes by precisely identifying the optimal operating conditions required for achieving desired product properties. These models utilize proximate biomass data to predict the elemental compositions of N2 and H2. Assessment of both single and two hybrid models indicated that the introduced optimizers significantly enhanced the estimation of N2 and H2 when combined with Decision Tree (DT), with Decision Tree Coupled with Artificial Hummingbird Algorithm (DTAH) proving particularly effective. Notably, DTAH demonstrated outstanding performance with remarkable R 2 values of 0.990 for N2 and 0.992 for H2. Additionally, the minimal Root Mean Square Error (RMSE) values of 1.291 and 1.550 for N2 and H2 predictions respectively underscore the precision of DTAH, establishing it as a suitable choice for practical real-world applications.

Responses of soil microbial metabolism, function and soil quality to long-term addition of organic materials with different carbon sources

Biochar and green manure have been widely applied in agricultural production and are important means to achieve sustainable agriculture. However, there is limited research systematically and comprehensively exploring the response of soil microbiota and the changes in soil metabolomics after the addition of two different carbon source amendments to the soil, and the differential mechanisms of soil metabolomics between them remain unclear. In this study, a long-term field experiment (initiated in 2019) was conducted to investigate the effects of biochar and green manure application on soil nutrients and soil functions driven by soil microbes. Compared to the pure fertilizer treatment, biochar increased soil total carbon by 14.54% to 27.04% and soil available potassium by 4.67% to 27.46%. Ryegrass significantly increased soil available phosphorus and organic matter. Under different fertilization regimes, the ecological niches of soil microbes changed significantly. Network analysis revealed that long-term ryegrass returning reduced the complexity of soil microbial networks. Ryegrass and biochar increased dispersal limitation in fungal assemblages (reaching 93.33% and 86.67%, respectively), with biochar particularly enhancing variable selection in bacterial assemblages (accounting for 53.33%). Variation partitioning analysis based on redundancy analysis indicated that humic substances had the highest explanatory power for microbial community variation, with humic substances explaining 38.49% of bacteria and 52.19% of fungi variation. The ryegrass treatment mainly changed the abundance of carbohydrates (CH), amines (AM), c (AH), and lipids (LP), while the BC treatment mainly altered the abundance of organic acids (AC), amines (AM), and carbohydrates (CH). Meanwhile, both treatments significantly reduced the bisphenol A, one of the soil pollutants. Ryegrass incorporation significantly increased the abundance of genes related to soil C, N, P, and S cycling, especially genes involved in carbon decomposition, while biochar significantly enhanced the abundance of nitrogen fixation genes nifH and Hao in soil. Random forest model results indicated that carbohydrates, alcohols, aromatics (AR), and ester (ES) were the main categories of metabolites in soil influenced by differential microbes, and Finegoldia served as a common important metabolic driving species. In summary, this study reveals the processes of soil function, microbial community succession, and metabolism driven by ryegrass and biochar, providing important insights for optimizing soil management and improving soil quality.Graphical

Emerging Low Detection Limit of Optically Activated Gas Sensors Based on 2D and Hybrid Nanostructures

Gas sensing is essential for detecting and measuring gas concentrations across various environments, with applications in environmental monitoring, industrial safety, and healthcare. The integration of two-dimensional (2D) materials, organic materials, and metal oxides has significantly advanced gas sensor technology, enhancing its sensitivity, selectivity, and response times at room temperature. This review examines the progress in optically activated gas sensors, with emphasis on 2D materials, metal oxides, and organic materials, due to limited studies on their use in optically activated gas sensors, in contrast to other traditional gas-sensing technologies. We detail the unique properties of these materials and their impact on improving the figures of merit (FoMs) of gas sensors. Transition metal dichalcogenides (TMDCs), with their high surface-to-volume ratio and tunable band gap, show exceptional performance in gas detection, especially when activated by UV light. Graphene-based sensors also demonstrate high sensitivity and low detection limits, making them suitable for various applications. Although organic materials and hybrid structures, such as metal–organic frameworks (MoFs) and conducting polymers, face challenges related to stability and sensitivity at room temperature, they hold potential for future advancements. Optically activated gas sensors incorporating metal oxides benefit from photoactive nanomaterials and UV irradiation, further enhancing their performance. This review highlights the potential of the advanced materials in developing the next generation of gas sensors, addressing current research gaps and paving the way for future innovations.

Challenges and Prospects of Electrolyte Design for Lithium‐Sulfurized Polyacrylonitrile Batteries

Sulfurized polyacrylonitrile (SPAN) is regarded as a promising organic sulphur cathode material for lithium‐sulfur (Li‐S) batteries. It undergoes a solid‐solid conversion without forming polysulfide intermediate phases, overcoming the poor electrochemical performance caused by the shuttle effect of elemental S cathodes. However, the realization of this unique conversion mechanism requires to employ appropriate electrolytes. Furthermore, the direct application of metallic Li as the anode unavoidable introduces a series of issues triggered by Li dendrites in Li‐SPAN batteries, such as low lifespan, short circuits, fire, etc. In this review, we endeavor to encapsulate recent advancements in electrolyte research, with a particular focus on the intrinsic relationship between the solvation structure of the electrolyte and the interfacial chemistry of the Li anode and SPAN electrode, aim to provide insights into the electrolytes design for high performance Li‐SPAN full batteries.

Broadband THz Wave Generation and Detection in Organic Crystal PNPA at MHz Repetition Rates

AbstractOrganic nonlinear optical (NLO) crystals have emerged as efficient room‐temperature emitters of broadband THz radiation with high electric field strengths. Although initially confined to high‐pulse‐energy excitation in the millijoule range with kHz rates, recent efforts have focused on tailoring the physical properties of organic NLO materials for compatibility with popular MHz‐rate telecommunication wavelength lasers emitting nanojoule energy pulses. This is motivated by the large potential of such crystals for more portable and user‐safe spectroscopic systems, additionally complemented by their room‐temperature field‐sensitive THz detection capabilities. In this work, the MHz‐rate operation of the organic crystal PNPA ((E)‐4‐((4‐nitrobenzylidene)amino)‐N‐phenylaniline), which was recently discovered through data mining algorithms and reported to surpass the conversion efficiency of rivaling NLO crystals at 1 kHz repetition rate is demonstrated. Using a compact 200 mW Er:fiber laser producing 18 fs pulses at 50 MHz repetition rate, the THz field generation and detection capabilities of PNPA via performing gas phase spectroscopy in the 1.3–8.5 THz range are demonstrated. A dynamic range of 40 dB over 3.6 s and 70 dB over 2 h is obtained. The work extends the family of organic crystals compatible with telecommunication‐wavelength excitation using nJ pulses for spectroscopy beyond 5 THz.

Performance Assessment of Confined Tube Aerators in Parallel Configuration

Aeration plays a major role in the activated-sludge wastewater treatment process. Microbes require an oxygen-enriched environment to digest organic materials and remove nutrients from the wastewater stream. For providing this oxygen, artificial aeration is required, which is responsible for the majority of energy use in treatment plants. Typically, this is accomplished with diffused aerators, where pressurized air is forced through a porous medium at the bottom of deep basins, and bubbles float up through the water column transferring oxygen in the process. This is a relatively energy-intensive process, which is prone to fouling at the porous media. In this study, a Confined Tube Aeration (CTA) system is proposed, where a pump forces water through a Venturi injector, where air is naturally drawn in. At the Venturi discharge, the flow is diverted to a coiled tube in which oxygen transfer occurs. This study analyzes the effect of parallelizing the CTA system with multiple injectors and at varying pump speeds (flow rates). Using experimental and analytical means, the maximum standard aeration efficiency was found to be with three injectors in parallel, at maximum pump speed, and utilizing a CTA with diameter 31.75 mm and length 3.048 m. This value was found to be 0.542 kg O2/kWh, and represents a 25% increase over the single-injector case. Although the analyses herein utilize a relatively small (0.746 kW) pump, these results indicate that CTA systems may scale well to larger pump sizes necessary for full-scale municipal wastewater treatment.

Synthesis, Structure, and Light Absorption of Octanoyl Amino Acids

Amino acid lanthanide complexes are a promising class of environmentally friendly and non-toxic optical organic materials that find extensive applications in biomedicine, molecular probes, and optical devices. In this study, three amino acid lanthanide complexes, octanoyl glycine gadolinium (Gd(oct-ala)3×H2O), octanoyl serine gadolinium (Gd(oct-ser)3×H2O), and octanoyl phenylalanine gadolinium (Gd(oct-phe)3×H2O), were synthesized by reacting octanoyl amino acid ligands with gadolinium chloride. The coordination structure of the gadolinium complexes was determined by elemental analysis and infrared spectroscopy. XRD and polarized light microscopy confirmed the amorphous structure of the complexes. DSC and TG-DTA were used to investigate the thermodynamic stability of the gadolinium complexes, and their solubility and UV-visible light absorption properties were also evaluated. Our results demonstrate that all three gadolinium complexes exhibit excellent UV-visible light absorption performance, with the Gd(oct-phe)3×H2O containing a phenyl ring showing the highest light absorption efficiency.

Boosting the Efficiency of Perovskite/Organic Tandem Solar Cells via Enhanced Near-Infrared Absorption and Minimized Energy Losses.

The compatibility of perovskite and organic photovoltaic materials in solution processing provides a significant advantage in the fabrication of high-efficiency perovskite/organic tandem solar cells. However, additional recombination losses can occur during exciton dissociation in organic materials, leading to energy losses in the near-infrared region of tandem devices. Consequently, a ternary organic rear subcell is designed containing two narrow-bandgap non-fullerene acceptors to enhance the absorption of near-infrared light. Simultaneously, a unique diffusion-controlled growth technique is adopted to optimize the morphology of the ternary active layer, thereby improving exciton dissociation efficiency. This innovation not only broadens the absorption range of near-infrared light but also facilitates the generation and effective dissociation of excitons. Owing to these technological improvements, the power conversion efficiency (PCE) of organic solar cells increased to 19.2%. Furthermore, a wide-bandgap perovskite front subcell is integrated with a narrow-bandgap organic rear subcell to develop a perovskite/organic tandem solar cell. Owing to the reduction in near-infrared energy loss, the PCE of this tandem device significantly improved, reaching 24.5%.

Low‐Temperature Flexibility of Chiral Organic Crystals with Highly Efficient Second‐Harmonic Generation

Flexible crystals with unique mechanical properties have presented enormous applications in optoelectronics, soft robotics and sensors. However, there have been no reports of low‐temperature‐resistant flexible crystals with second‐order nonlinear optical properties (NLO). Here, we report the flexible chiral Schiff‐base crystals capable of efficient second harmonic generation (SHG). Both enantiomers and racemic modifications of these crystals are mechanically flexible in two directions at both room temperature and at ‐196 °C, although their mechanical responses differ. The enantiomers display SHG with an intensity of up to 12 times that of potassium dihydrogenphosphate (KDP) when pumped at 980 nm, and they also have high laser‐induced damage thresholds (LDT). Even when bent, the crystals retain strong second harmonic generation, although with a different intensity distribution depending on the polarization, compared to when they are straight. This work describes the first instance of flexible organic crystal with NLO properties and lays the foundation for the development of mechanically flexible organic NLO materials.

Natural polymers for emerging technological applications: cellulose, lignin, shellac and silk

AbstractIn an effort to stave off the growth of electronic waste (e‐waste) that poses a critical environmental dilemma, scientists often look into nature as an unending inspirational pool of materials and chemical processes that ensure functionality, performance and safe dissolution at the end of life cycle. This short review highlights only four organic polymer materials of natural origin (i.e. cellulose, lignin, shellac and silk) from the very large pool of natural (bio)polymeric materials and looks not only into the recent developments at the industrial scale but also into the emerging niche applications of these materials, while highlighting their implementation into electronics and sensor development. This review exemplifies that natural polymeric materials have great potential for the development of eco‐friendly electronics, in other words the class of industrial products that has carefully considered the important issues of biocompatibility, biodegradability (even compostability), cost of production and energy expanded in production (i.e. the carbon footprint). © 2024 The Author(s). Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Surface warming in Svalbard may have led to increases in highly active ice-nucleating particles

The roles of Arctic aerosols as ice-nucleating particles remain poorly understood, even though their effects on cloud microphysics are crucial for assessing the climate sensitivity of Arctic mixed-phase clouds and predicting their response to Arctic warming. Here we present a full-year record of ice-nucleating particle concentrations over Svalbard, where surface warming has been anomalously faster than the Arctic average. While the variation of ice-nucleating particles active at around −30 °C was relatively small, those active at higher temperatures (i.e., highly active ice-nucleating particles) tended to increase exponentially with rising surface air temperatures when the surface air temperatures rose above 0 °C and snow/ice-free barren and vegetated areas appeared in Svalbard. The aerosol population relevant to their increase was largely characterized by dust and biological organic materials that likely originated from local/regional terrestrial sources. Our results suggest that highly active ice-nucleating particles could be actively released from Arctic natural sources in response to surface warming.

Extraction and Physicochemical Characterization of Hydroxyapatites From Horse Humerus Bones of Different Ages (1, 3, 6, and 8 Years old) Calcined at Low Temperature.

The aim of this work is to investigate the changes in the physicochemical properties of hydroxyapatite (HAp) extracted from horse humerus bones of different ages (1, 3, 6, and 8 years) subjected to low temperature calcination (600°C). Thermal analysis revealed significant mass loss due to water, collagen, organic compounds, carbonates, and age-related magnesium out-diffusion. Higher fat content in older bones contributed to increased mass loss. Phosphorus content remained constant across age groups, while calcium and sodium showed age-related fluctuations. Magnesium levels decreased with age, emphasizing its importance for early bone development. The Ca/P ratio deviated from the stoichiometric values due to additional ions from biogenic sources. Infrared spectroscopy identified functional groups in carbonated HAp, with changes observed before and after calcination. The full width at half maximum (FWHM) of the 961 cm-1 band decreased with age, indicating improved crystalline quality. The molar absorption coefficients provided information on the changes in molecular concentration and emphasized the differences between the age groups. X-ray analysis revealed nanocrystalline HAp in all samples, with crystallite size increasing with age. Rietveld analysis showed that the lattice parameters were affected by the presence of organic material, but the lattice constants remained stable, confirming high crystallinity independent of age. TEM analysis confirmed nanocrystalline structures, with crystallite size increasing with age. SEM images showed the characteristic porosity of calcined HAp, with particle size correlating positively with age. Calcination at 600°C preserved the nanoscale properties and microcrystal formation. Raman spectroscopy confirmed the identity of HAp, with FWHM variations indicating age-related changes in crystalline quality. EHAp1 showed increased FWHM, indicating lower crystalline quality and increased trace element content.

Carbon-containing pyrite spherules: mineral biosignatures in black smokers?

Abstract. Sulfide- and sulfate-rich hydrothermal vents are involved in Earth's major geochemical cycles. An outstanding scientific question consists of finding out whether certain minerals found in hydrothermal chimneys are influenced more or less directly by microorganisms living at high temperatures (thermophiles or hyperthermophiles) in these environments. Here we report the morphological, textural and chemical characterization of pyrite crystals collected across a section of a chimney from the Trans-Atlantic Geotraverse hydrothermal site, sampled from the inner, hotter portion to the external, cooler portion, providing a promising approach to the search for hyperthermophilic biosignatures. The internal and middle portions of the chimney mainly harbour cube-shaped pyrite containing low quantities of hydrocarbons and thermally matured organic compounds. In contrast, the samples from the external portion contain pyrite spherules composed of a mosaic of slightly disoriented domains that include large amounts of organic material chemically consistent with thermally matured biogenic organic compounds. These characteristics make them comparable but not identical to pyrite spherules produced in the laboratory in the presence of hyperthermophilic archaea of the order Thermococcales. Differences include larger crystalline domains and more thermally matured organic compounds. Such features could be consistent with the thermal transformation of pyrite spherules produced by (or at least in the presence of) living cells. However, it remains impossible to completely rule out an abiotic origin without further isotopic investigation and experimental studies on the abiotic production of pyrite spherules in the presence of organic compounds and under hydrothermal conditions.

SOURCE APPORTIONMENT OF ATMOSPHERIC AND SEDIMENTARY PAHS FROM KOLKATA, INDIA USING COMPOUND-CLASS-SPECIFIC RADIOCARBON ANALYSIS (CCSRA)

ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) are major air pollutants that are ubiquitously produced by the combustion of organic materials, and it is extremely important to identify their pollution sources. In this study, molecular fingerprinting and compound class-specific radiocarbon dating (CCSRA) were performed on PAHs from canal sediments and air samples collected in Kolkata, India’s third largest city (population approximately 16 million), where PAHs pollution has been a serious problem. Average PAH (Σ12-parent PAHs) concentrations in air samples were 65.1 ng m–3 in summer and 70.9 ng m–3 in winter and in canal sediments were 32.7 µg g–1, which are classified as “very high-level” pollution. Molecular fingerprinting using methyl-PAH/PAH (MPAHs/PAHs) ratios and isomer pair ratios with molecular weights of 178, 202, 228, and 276 suggested that wood and coal combustion were the dominant sources of PAHs in the sediment, and that atmospheric PAHs were influenced by oil combustion in addition to them. The fraction of contemporary carbon (ƒC) of sedimentary PAHs (0.056–0.100), together with the extremely low MPAHs/PAHs ratio results, lead to the conclusion that the major source of the high concentration of PAHs in the canals is from coal combustion. On the other hand, the ƒC of atmospheric PAHs (0.272–0.369) was close to the share of biomass fuels in India’s domestic fuel consumption in 2011 (about 35%). Furthermore, the observed ƒC-discrepancy between atmospheric and sedimentary PAHs in the same urban environment was interpreted to give an insight into the loading pathway of PAHs to canal sediments in Kolkata.

Development of an Interdisciplinary Approach to the Radiocarbon Dating of Earth Mortars from Alula Old Town (Saudi Arabia). Integration of Building Archaeology, Mortar Analysis and Radiocarbon Dating

Abstract This paper discusses the approach used to identify the most relevant chronological information on the historic development of the abandoned site of AlUla Old Town, in the northwest of the Kingdom of Saudi Arabia (Western Asia). The approach is based on the use of the radiocarbon method to date earth mortars samples and soil layers used to create the constructive sequence of some buildings and, in turn, the chronological evolution of the site. Eleven samples of organic material (i.e., charcoal and vegetable fibers) were carefully removed from mortar samples and soil levels from six buildings and structures in the northern and southern areas of the town. Buildings and soil layers were chosen for their stratigraphic relevance and conservation conditions, based on an initial archaeological analysis of both, buildings and underground structures. Laboratory-based mortar analysis led to the characterization of the mortar’s inorganic fraction, and to the isolation of the organic material for the radiocarbon dating. Results from the accelerator mass spectrometry (AMS) laboratory provides evidence of a Late Mamluk/Early Ottoman constructive phase (i.e., 15th–17th c. AD) of the Old Town that was only partially known until very recently. Furthermore, the results allowed the identification of an Ottoman phase (i.e., 17th–19th c. AD) during which most of the buildings and structures were rebuilt, and of a Late Ottoman phase (i.e., 19th–20th c. AD) representing the most recent interventions before the end of the Ottoman occupation of the area.

FEATURES OF WASHING WATER-SOLUBLE PHOSPHORUS-AMMONIUM SALTS OF FIREPROOF WOOD COATING

The article analyzes fire-resistant materials for wooden building structures and establishes the need to develop reliable methods of researching the process of washing out flame retardants from the surface of the building structure, which are necessary for the creation of new types of fire-resistant materials. Therefore, there is a need to determine the conditions for the formation of a barrier for leaching and to establish a mechanism for inhibiting the transfer of moisture to the material. In this regard, a mathematical model of flame retardant leaching has been developed, when a polymer shell made of organic material is used as a coating, which allows evaluating the effectiveness of the polymer shell based on the amount of flame retardant washed out. According to experimental data and theoretical dependences, the dynamics of release of flame retardants from the fire-resistant layer of the coating, which does not exceed 1.0%, is calculated, and accordingly provides fire protection of wood. The results of determining the loss of mass of the sample during exposure to water indicate an ambiguous effect of the nature of the protection on leaching. In particular, this assumes the availability of data sufficient for qualitatively carrying out the process of inhibiting moisture diffusion and identifying, on its basis, the moment in time when the decline in coating efficiency begins. Experimental studies have confirmed that a sample of fire-resistant wood after exposure to water for 30 days withstood the influence of heat flow. In particular, the loss of wood mass after temperature exposure was less than 6%, and the temperature of flue gases did not exceed 185 ºС. Thus, there are reasons to assert the possibility of targeted regulation of wood fire protection processes through the use of polymer coatings capable of forming a protective layer on the surface of the fire retardant material, which inhibits the rate of flame retardant leaching.

Organic waste recycling application increases N availability and mitigates N2O emission without crop yield penalty in the North China Plain

IntroductionAgricultural organic waste recycling can supply nutrients for crop production and partially replace chemical nitrogen fertilizers, which is beneficial for waste management and environmental protection. Nevertheless, comprehensive evaluation of the effects of different organic materials applications on crop yield and the environment is limited.MethodsTherefore, in this study, a comprehensive investigation of the synergistic effects of straw, pig manure, and biogas residue recycling on the wheat (Triticum aestivum L.) and maize (Zea mays L.) systems was carried out in the North China Plain. Field experiments were conducted from 2019 to 2021, comprising five treatments: straw (ST), pig manure (PM), and biogas residue (BR) partially replacing chemical nitrogen fertilizer, sole application of chemical nitrogen fertilizer (CF), and a control with no nitrogen application (WN).Results and discussionThe results showed that organic materials significantly increased soil total nitrogen (3.04%–9.10%) and N recovery efficiency (REN; 42.21%–44.99%), but pig manure was more beneficial in increasing crop yields (3.50%), especially wheat yields (8.72%), and REN was significantly higher than that of the other treatments. Organic materials performed differently in wheat and maize seasons, and wheat yield could be improved by organic materials return. Organic materials stimulated N2O emission in wheat season (4.28%–32.20%), while biogas residue inhibited the N2O emission in maize season (47.47%). The negative effect of straw and biogas residue on yield decreased with increasing years of return, and pig manure continued to contribute to yield. In conclusion, pig manure is the optimal alternative that can increase crop yield, soil N content, and REN without stimulating N2O emissions.