Experiment Observations Research Articles

Empowering farmer community with technology modernisation to improve rice farming performance through demonstration farms in East Java, Indonesia

Purpose Rice is a strategic commodity and staple food; thus, rice productivity should grow faster than the population. A public agricultural agency launched technology modernisation to improve rice farm performance. This study aims to assess the impact of technology modernisation on rice farming performance and evaluate farmer acceptance of such technology. Design/methodology/approach This study was conducted in 2023-2024, based on selected demonstration farms (demfarm) carried out during 2021-2022 in East Java, Indonesia, one of the rice bowls. Microeconomic theory of production and the double-differences approach were used as fundamental analyses. Farmers were purposively selected to participate in the demfarm. For comparison, farmers with existing technology adjacent to the demfarm were chosen accordingly. Rice production is considered an economic performance indicator, and factors related to socio-demographic and technical aspects were conceptualised using innovation and diffusion theory. Findings The results of demfarm were apparent. Technology modernisation improved rice farming’s economic performance. Farmer acceptance of such technology was relatively high at the first stage. There was no conflict between technology and local culture and norms. The technological package will likely be disseminated to farmers after adequate socialisation. Research limitations/implications This study engaged farmer innovators and early adopters in the demonstration farm. This needs more actions from farmers who are not categorised as innovators and early adopters, which dominate the farmer population. Practical implications Extension officials need field guidance to ensure continual technology adoption because of technology complexity. Originality/value The originality of the study is based on a field experiment and direct observation throughout a crop cycle, and the analysis is established using a solid theory and analytical framework.

Towards sustainable development goals: Leveraging multi-data remote sensing fusion for monitoring groundwater-induced bedrock subsidence dynamics in Egypt's Nile Valley

Egypt's Golden Triangle megaproject within Egypt's vision 2030, involving land reclamation in Qena Bend's densely populated governorate, develops sustainable land management strategies. Advanced technologies and low-cost remote sensing multi-data fusion are utilized to understand subsidence dynamics influenced by geologic structure, groundwater, climate change, and human activities in Egypt's Nile Valley. This approach identifies environmental hazards and provides a detailed explanation for groundwater-induced bedrock subsidence, aiding in informed decision-making and risk avoidance. Landsat images reveal 13% increased cultivation, 28.28% urban-growth, and decreased water by 8.46%, impacting groundwater resources and controlling the situation. The Gravity Recovery and Climate Experiment(GRACE) and Global Land Data Assimilation System (GLDAS) satellite observations reveal changes in water storage, impacting climate change, groundwater storage dynamics, and aquifer behavior. Historical data indicates a significant southwest-northeast gradient in precipitation from 5 to 60 mm. GLDAS shows soil moisture decline from 0.25 to 0.23 mm. GRACE (total water storage) depleting, then slightly increasing from 2020 to 2023 with an average value (−5 cm/yr). Groundwater storage increases in wet seasons, in 2015 showing (+3–4 mm), less than (+1 mm) in (2018), and (+6–8 mm) in (2020–2023). The NE-SW and NW-SE faults increase hydraulic connection and recharge from aquifers, causing groundwater circulation and karstification in Eocene limestone aquifers, posing risks to urban development and human safety. The InSAR (Synthetic Aperture Radar) measures ground subsidence over time, revealing a range of (−0.04 to −0.07m) in the northwest to (+0.03m) in the southeast, with average subsidence (-4 cm), primarily associated with increased groundwater storage motivate the interaction between the carbonate and groundwater. The ArcGIS overlay model divides the region into three zones: northern, middle, and southern, each with varying degrees of displacement and groundwater storage. The findings emphasize the significance of remote sensing in hazard evaluation for development planning due to its cost-effectiveness and accuracy, applicable globally in hydrogeologically similar areas.

Program for forming psychological readiness for professional communication in future pre-school education teachers during the process of studying at university

Introduction. The article deals with the problem of preparing specialists of the preschool education system for future professional activity in the process of studying at higher school. The authors present the basic concept for the creation and implementation of the main stages of the program for the formation of psychological readiness among students of preschool education for professional communication with all subjects of the educational process. The modular principle of designing a program based on the main components of the structure of psychological readiness is discussed, and the need to increase the practical training of future teachers of preschool education is noted. Materials and Methods. The research used: theoretical methods: analysis of scientific publications, psychological and pedagogical literature; synthesis and interpretation, method of generalization and systematization of information, modeling of the process of formation of psychological readiness for professional communication; empirical research methods: psychological and pedagogical experiment, testing, direct and indirect observation, proximetric techniques; data analysis methods: methods of mathematical statistics, quantitative and qualitative analysis of the results. Results. The authors substantiate and concretize the scientific and theoretical foundations, approaches and principles, organizational, psychodidactic and psychological-pedagogical conditions, present a detailed approbation of the program, assess the dynamics of the formation of psychological readiness for professional communication among future teachers of preschool education. The program allows undergraduate students to consistently master general cultural and general psychological communicative competencies; skills, abilities, actions of planning, designing, building, accumulating individual experience of interpersonal and professional communication with different subjects of the educational process; building personalized communication models with different target groups and subjects of education; to form the initial style of professional communication of the future teacher, his value-semantic, a substantial and structural-organizationaloutline. Discussion and Conclusions. The performed research has shown the need and possibility of systematic and systematic formation of psychological readiness for professional communication among students of preschool education in the process of studying at a university. The psychological readiness of students of preschool education has its own characteristics and correlates with the requirements for the professional competencies of a future teacher of preschool education.

The factors that influence protostellar multiplicity

Context. Protostellar multiplicity is common at all stages and mass ranges. However, the factors that determine the multiplicity of protostellar systems have not been systematically characterized through their molecular gas. Aims. We characterize the physical properties of the Perseus molecular cloud at ≥5000 AU scales by mapping the diagnostic molecular lines. Methods. We used Nobeyama 45m Radio Observatory (NRO) on-the-fly maps of HCN, HNC, HCO+, and N2H+ (J=1–0) toward five subregions in Perseus, complemented with single-pointing Atacama Pathfinder Experiment (APEX) observations of HNC (J = 4–3), to derive the physical parameters of the dense gas. The spatial resolutions of both observations were ~18″, which is equivalent to ~5000 AU scales at the distance of Perseus. The kinetic gas temperature was derived from the I(HCN)/I(HNC) J ratio, and the H2 density was obtained from the HNC J=4–3/J=1–0 ratio. These parameters were used to obtain the N2H+ (cold) and HCO+ (warm) gas masses. The inferred and derived parameters were then compared to source the parameters, including protostellar multiplicity, bolometric luminosity, and dust envelope mass. Results. The inferred mean kinetic gas temperature (I(HCN)/I(HNC) J=1–0 ratio; ranging between 15 and 26 K), and H2 volumetric density (HNC J=4–3/J=1–0; 105−106 cm−3) are not correlated with multiplicity in Perseus. The derived gas and dust masses, 1.3 to 16 × 10−9 M⊙ for the cold-gas mass (N2H+), 0.1 to 25 M⊙ for the envelope dust masses (850 μm), and 0.8 to 10 × 10−10 M⊙ for the warm-gas mass (HCO+), are correlated to multiplicity and to the number of protostellar components. The warm-gas masses are lower by a factor of 16 than the cold-gas masses. Conclusions. The gas and dust mass is correlated to multiplicity at ~5000 AU scales in Perseus. Higher-order multiples tend to have higher gas and dust masses in general, while close binaries (separations ≤7″) and single protostars have similar gas and dust mass distributions. On the other hand, the H2 density and kinetic gas temperature are not correlated with multiplicity.

Full-field experiment-aided virtual modelling framework for inverse-based stochastic prediction of structures with elastoplasticity

Forecasting of stochastic ductile failures in fabrication and service stages are challenging tasks of advanced structures in practical engineering. Due to the prohibitive costs of repetitive experimental tests to quantify optimal failure-related parameters, numerous studies have turned to simulation-based uncertainty quantification. However, the credibility of these approaches is frequently doubted by the function-generated distribution of random data involved. Thus, an accurate assessment of the material parameters ascertains the appropriate estimation of uncertain parameters, which is essential for the risk/safety assessment of structures in different stages. In this paper, a full-field experiment-aided virtual modelling framework for inverse-based prediction of stochastic elastoplastic failure (EVMF-ISP) is proposed to deliver precise insights regarding the effective distribution range of mechanical parameters. To this end, all available experiment observations serve as the reference for assessing the prior and posterior probability density of the unknown parameters through the real-time inverse uncertainty quantification (UQ) module. The framework can be divided into three parts, where initially a pre-virtual model (PRVM) is formulated, and Bayesian inference is implemented to propagate the experiment observations backwards to ascertain the uncertain parameters. Then, an advanced multidimensional slice sampling method is developed to deal with the derived complex posterior probability density function (PDF) of mechanical parameters. In the end, a reliable stochastic elastoplastic analysis can be conducted with the revised uncertain samples and finalised with post-virtual models (POVMs) for the concerned structures. Such that, accurate and efficient determination of nonlinear response of structures can be directly predicted. The EVMF-ISP framework is logically presented and thoroughly illustrated with practical applications.

Simulation study of the influence of drifts on the upstream and target heat flux width under different B T directions

The heat flux width (λq ) is a key parameter determining the heat load at divertor targets. In recent years, drifts have been found to play a remarkable role in the edge plasma transport, while its influence on λq has not been well understood. Investigations of the influence of drifts on λq , systematic simulations using the SOLPS-ITER code are performed in this work. The statistics of the simulation results show that the drift under favorable/unfavorable B T tends to increase the λq in the outer/inner side and decrease the λq in the other side, which is consistent with the experiment observations. At the upstream and the target, the mechanisms of the influence of the drifts on λq are different. The upstream λq (λq ,u) is directly affected by the drift-induced convective heat flux, while λq at the target (λq ,t) is indirectly influenced through heat conduction (in the high-recycling regime) and the sheath (in the detached regime) due to the change of plasma parameters there. Furthermore, the synergetic effect of geometry and drift under favorable B T leads to an anomalously large λq ,t in the inner side at high density.

Highly efficient inverse lumped modeling for the pre-strained circular dielectric elastomer

The equi-biaxially pre-strained circular dielectric elastomer actuator (PCDEA) is a classical actuator configuration to demonstrate the electromechanical deformation mechanism of dielectric elastomer. Till now, there still lacks an effective method to analyze the non-uniform voltage-induced deformation of PCDEA with both high accuracy and low computational cost. Besides, the inverse problem that determines the voltage input for a desired deformation is also a hard problem for the current modeling approaches. In this work, a novel shape function approximation method is proposed to model the non-uniform deformation of PCDEA in a highly accurate lumped-parameter way. The method can solve both the inverse problem and forward problem of the PCDEA, making it possible to position the onset of electromechanical instability (EMI) of this configuration. Detailed comparisons are made between this method and high-resolution finite element analysis to verify its accuracy. This method also features low computational cost, providing opportunities for developing model-based real-time control and proprioception techniques. Further investigation is also carried out on how material types and configurational parameters interact with PCDEAs’ performance, along with checking the findings with experiment observation. Guidelines for DE material development and actuator design are also summarized accordingly.

Dry Reforming of Methane on Ni/LaZrO2 Catalyst under External Electric Fields: A Combined First-Principles and Microkinetic Modeling Study.

Dry reforming of methane (DRM) reaction has great potential in reducing the greenhouse effect and solving energy problems. Herein, the DRM reaction mechanism and activity on Ni16/LaZrO2 catalyst under electric fields were comprehensively investigated by combining density functional theory calculations with microkinetic modeling. The results showed that La doping increases the interaction between Ni and ZrO2 by Ni cluster transfer of more electrons. The adsorption strength of species followed the order Ni16/ZrO2 > Ni16/LaZrO2, which is consistent with the results for the d-band center but opposite to the metal-support interaction. The best DRM reaction path on Ni16/LaZrO2 was the CH2-O pathway, which is different from the CH-O pathway on Ni(111) and Ni16/ZrO2. Both positive and negative electric fields of strong and weak metal-support interactions reduced the energy barrier of DRM reaction. Importantly, our results showed that the more dispersed and smaller Ni12/LaZrO2 model by considering the dispersing effect induced by La doping, which displayed very different results from that of Ni16/LaZrO2: reduced the energy barrier for methane decomposition, thereby promoting DRM reaction activity. Microkinetic results showed that the carbon deposition behavior of DRM becomes weaker on Ni16/LaZrO2 due to the suppression of methane decomposition in the presence of La doping compared to Ni16/ZrO2, but the opposite result is obtained on Ni12/LaZrO2. The order of DRM reactivity was Ni16/LaZrO2 < Ni16/ZrO2 < Ni12/LaZrO2, which is consistent with the experiment observations. The conversion of methane and CO2 was higher in positive electric fields than in negative electric fields at low temperatures, but the results were opposite at high temperature. Negative electric fields can improve the carbon deposition resistance of Ni-based catalysts compared to positive electric fields. The degree of rate control analysis showed that CHx* oxidation also plays an important role in the DRM reaction. We envision that this study could provide a deeper understanding for guiding the widespread application of electric field catalysis.

Microstructure evolution during directional solidification of 2009Al/SiCp at different pulling velocities: Modeling and Experiment

The cellular automaton-lattice Boltzmann method-immersed moving boundary coupled model is established to study the microstructure evolution during the solidification process of 2009Al/SiCp. After several model benchmarks, the natural convection of liquid phase and its effect on particle settlement under different pulling velocities were studied firstly. The results showed that at higher pulling velocity, the particle decelerates downward before contacting with dendrite front due to intensified natural convection. At lower pulling velocity, the particle decelerates gradually until a change in direction and upward movement. As the particle approach the tip of the dendrite, the particle experiences a brief upward movement before contacting the dendritic front. Then the convection induced by particles has an impact on the distribution of solutes in the liquid phase. It has been observed that at lower pulling velocity, there is a significant difference in solute distribution at the solidification front. The primary reason for this phenomenon is the higher solute concentration near the solidification front at lower pulling velocity, rather than the higher liquid phase flowing rate. Finally, our model investigated the microstructure evolution process during the directional solidification process of 2009Al/SiCp at different pulling velocities. The results indicate a good agreement between the simulation results and experiment observations.

Effects of polyvinylpyrrolidone additive on structures and properties of Poly(m-phenylene isophthalamide) hollow fiber membranes -experiment observation and computation approach

This study systematically investigates the effect of introduction of polyvinylpyrrolidone (PVP) used as a hydrophilic additive and its molecular weight change on the morphological, mechanical properties, and membrane performances of poly(m-phenylene isophthalamide) (PMIA) hollow fiber (HF) membranes prepared by dry-jet wet spinning method. The results of the morphological and mechanical properties clearly show an increased proportion of a sponge-like pore structure and an overall improvement in the mechanical properties of the PMIA HF membranes with higher molecular weight PVP, respectively. Interestingly, molecular dynamics simulation showed that the presence of PVP within the PMIA matrix activated the overall movement of PMIA molecules, suggesting that the overall flexibility of the system, which can potentially inhibit the collapse of relatively brittle membranes, is increased by the presence of PVP. Finally, as the molecular weight of PVP increases, a typical trade-off phenomenon is observed on PMIA HF membranes, where the water permeability decreases while the rejection rate increases. Based on these results, the findings on the influence of PVP additive and its potential as a reinforcing agent observed in this study through experimental analysis and computational approaches are expected to provide new insights into the development of high-performance polymeric HF membranes.

Experimental and kinetic modeling study on auto-ignition of ammonia/n-heptane mixtures at intermediate temperatures

Ignition delay times (IDTs) were measured in a shock tube facility for NH3/n-heptane mixtures with NH3 concentrations in the blending fuel ranging from 0.3 to 0.95 by molar fraction. The measurements were conducted under low pressure of 2 atm and intermediate temperatures of 1350–1500 K at equivalence ratios of 0.5, 1, and 2. With the increase of n-heptane content or equivalence ratio, there is a decrease in the IDTs of NH3/n-heptane mixtures at intermediate temperatures. A detailed mechanism was updated in this study based on the mechanism of Dong et al. Subsequently, the proposed mechanism was compared to existing blending mechanisms of ammonia and n-heptane in terms of laminar burning velocities (LBVs), IDTs, and species profiles reported in literature. The present model improved the predictions in reproducing the performed experimental measurements compared to previous mechanisms. Finally, rate of production (ROP), sensitivity analysis, and instantaneous and cumulative reaction path analysis were performed to interpret the experiment observations and deepen the understanding of auto-ignition kinetics of ammonia and n-heptane. The results indicate that intermediate species, such as C2H4 and C3H6, characterized by long lifespans and high concentrations during n-heptane decomposition, play a crucial role at elevated temperatures, while the significance of n-heptane dehydrogenation by NH2 diminishes with increasing temperature.

Benchmarking multimodel terrestrial water storage seasonal cycle against Gravity Recovery and Climate Experiment (GRACE) observations over major global river basins

Abstract. The increasing reliance on global models for evaluating climate- and human-induced impacts on the hydrological cycle underscores the importance of assessing the models' reliability. Hydrological models provide valuable data on ungauged river basins or basins with limited gauge networks. The objective of this study was to evaluate the reliability of 13 global models using the Gravity Recovery and Climate Experiment (GRACE) satellite's total water storage (TWS) seasonal cycle for 29 river basins in different climate zones. Results show that the simulated seasonal total water storage change (TWSC) does not compare well with GRACE even in basins within the same climate zone. The models overestimated the seasonal peak in most boreal basins and underestimated it in tropical, arid, and temperate zones. In cold basins, the modeled phase of TWSC precedes that of GRACE by up to 2–3 months. However, it lagged behind that of GRACE by 1 month over temperate and arid to semi-arid basins. The phase agreement between GRACE and the models was good in the tropical zone. In some basins with major underlying aquifers, those models that incorporate groundwater simulations provide a better representation of the water storage dynamics. With the findings and analysis of our study, we concluded that R2 (Water Resource Reanalysis tier 2 forced with Multi-Source Weighted Ensemble Precipitation (MSWEP) dataset) models with optimized parameterizations have a better correlation with GRACE than the reverse scenario (R1 models are Water Resource Reanalysis tier 1 and tier 2 forced with the ERA-Interim (WFDEI) meteorological reanalysis dataset). This signifies an enhancement in the predictive capability of models regarding the variability of TWSC. The seasonal peak, amplitude, and phase difference analyses in this study provide new insights into the future improvement of large-scale hydrological models and TWS investigations.

Using machine learning techniques to reconstruct the signal observed by the GRACE mission based on AMSR-E microwave data

Abstract This study delves into the synergy between remote sensing and satellite gravimetry, focusing on the utilization of Advanced Microwave Scanning Radiometer (AMSR-E) data for modeling delta Total Water Storage (ΔTWS) values derived from the GRACE mission. Various machine learning algorithms were employed to investigate the concordance between Gravity Recovery and Climate Experiment (GRACE) and AMSR-E observations. Despite the limited correlation in circumpolar permafrost areas, ΔTWS was successfully modeled with an accuracy of a Root Mean Square Error (RMSE) of 3.5 cm. The Amazon region exhibited a notable model error, attributed to significant ΔTWS amplitude; the overall model quality was affirmed by Normalized Root Mean Square Error (NRMSE) and Nash-Sutcliffe Efficiency (NSE) metrics. Importantly, the effectiveness of AMSR-E Soil Moisture (SM) data, encompassing C (frequency of 4–8 GHz) and X (frequency of 8–12 GHz) ranges (~0.04 m and ~0.03 m wavelength, respectively) in modeling ΔTWS, even in heavily forested equatorial regions, was demonstrated.

Modeling Ion Conic Formation in Io's Auroral Footprint

AbstractEnergetic ions outflowing from Jupiter's atmosphere was observed during Juno's 12th perijove crossing (PJ12) in the vicinity of Io's auroral footprint and reported by prior studies. It was hypothesized that Wave‐Particle Interactions (WPI) with ion cyclotron waves observed coincident with the ion outflow may be responsible for the heating and subsequent outflow. This study uses numerical simulation and data model comparison to test whether ion cyclotron resonant heating is indeed a plausible mechanism to explain the intense ion outflow observed. Our simulations assume that the wave heating is of limited duration due to Io's footprint motion. The simulations are moreover compared to the previously published Jupiter Energetic Particle Detector Instruments (JEDI) observations at high energies, and the lower energy Jovian Auroral Distributions Experiment (JADE) observations that were not previously reported. We find that the ion cyclotron resonant heating mechanism can indeed lead to ion conic formation and strong vertical transport under certain assumptions about the distribution of wave power with altitude. We also find that the ion outflow is energized quickly with very rapid formation of the ion conic distribution. The implications of the intense ion outflow are also examined and it is found that such strong wave heating can lead to a depletion of the topside ionosphere.

An explicit material point and finite volume sequentially coupled method for simulating large deformation problems in saturated soil

An explicit material point and finite volume sequentially coupled method (MPM-FVM) is developed using u-p form coupling formulations for the simulation of large deformations in saturated soil. In MPM-FVM, the momentum conservation equation is solved by MPM under the updated Lagrange framework, and the mass conservation equations are solved by FVM under the Euler framework. The numerical implementation of an explicit sequentially coupled algorithm is developed considering the tradeoffs between computational cost and numerical stability. The critical time step of u-p form governing equations is derived using the Von Neumann method, which is found to be much greater than the u-U form explicit MPM at low permeability, allowing for high numerical stability. Three numerical cases are presented to demonstrate the stability, efficiency, and effectiveness of the developed MPM-FVM method. The simulation of a saturated one-dimensional soil column subjected to quasi-static and dynamic loads validates the method, and highlights its greater efficiency and accuracy compared to standard solid–fluid coupled MPM methods. The large deformation simulation capability of the method is exhibited via simulation of a saturated slumping block. In real-world application, simulation results obtained using method achieves excellent agreement with the experiment measurements and observations of the Selborne landslide experiment.

Effects of Different Mixture Ratios of Common Vetch and Triticale on Forage Yield and Silage Quality

In order to obtain high amounts and quality forage in legume grain mixtures, the mixture ratios must be adjusted well. Since grains are tillered due to their physiology, their ratios in roughage are different from the mixing ratios in planting. This is a factor that increases roughage yield and reduces crude protein rate and yield. In addition, in cases where grains are insufficient in terms of minerals in animal nutrition and are planted in mixtures with legumes, the rapid development and high yield effects of grains should be combined with the balanced nutrition potential of legumes in order to obtain better quality feed. In this study, 100% Vetch, 100% Triticale, 75% Vetch + 25% Triticale, 50% Vetch + 50% Triticale, 25% Vetch + 75% Triticale were planted in Sakarya conditions and the effect of the mixture ratios on grass yield was revealed. Additionally, silage was made from the mixtures obtained and the effect of the applied mixture ratios on silage quality was determined. Field trials of the research were carried out in the trial areas of Sakarya University of Applied Sciences, Faculty of Agriculture. In the experiment, plant height, green and dry forage yield observations were taken. At the end of the maturation period, silage was made in 2 kilogram containers from each parcel as a silage quality criterion; silage dry matter ratio, silage pH, crude protein ratio, ADF and NDF observations were taken. By calculating the physical and sensory analyzes and flieg point used to determine silage quality, the silages obtained from the mixtures were defined in detail by chemical, physical and sensory analyzes and the flieg point. In the study, the highest green forage yield, hay yield, crude protein, ADF, NDF ratio and flieg point were obtained from 100% Vetch, 100% Triticale, 100% Vetch, 100% Triticale, 100% Triticale and 50% Vetch+50% Triticale mixtures, respectively.

Nuclear Matter Properties and Neutron Star Phenomenology Using the Finite Range Simple Effective Interaction

The saturation properties of symmetric and asymmetric nuclear matter have been computed using the finite range simple effective interaction with Yukawa form factor. The results of higher-order derivatives of the energy per particle and the symmetry energy computed at saturation, namely, Q0, Ksym, Kτ, Qsym, are compared with the corresponding values extracted from studies involving theory, experiment and astrophysical observations. The overall uncertainty in the values of these quantities, which results from a wide spectrum of studies described in earlier literature, lies in the ranges −1200≲Q0≲400 MeV, −400≲Ksym≲100 MeV, −840≲Kτ≲−126 MeV and −200≲Qsym≲800 MeV, respectively. The ability of the equations of state computed with this simple effective interaction in predicting the threshold mass for prompt collapse in binary neutron star merger and gravitational redshift has been examined in terms of the compactness of the neutron star and the incompressibility at the central density of the maximum mass star. The correlations existing between neutron star properties and the nuclear matter saturation properties have been analyzed and compared with the predictions of other model calculations.

Flight of the Bumblebee: the Early Excess Flux of Type Ia Supernova 2023bee Revealed by TESS, Swift, and Young Supernova Experiment Observations

We present high-cadence ultraviolet through near-infrared observations of the Type Ia supernova (SN Ia) 2023bee at D = 32 ± 3 Mpc, finding excess flux in the first days after explosion, particularly in our 10 minutes cadence TESS light curve and Swift UV data. Compared to a few other normal SNe Ia with early excess flux, the excess flux in SN 2023bee is redder in the UV and less luminous. We present optical spectra of SN 2023bee, including two spectra during the period where the flux excess is dominant. At this time, the spectra are similar to those of other SNe Ia but with weaker Si ii, C ii, and Ca ii absorption lines, perhaps because the excess flux creates a stronger continuum. We compare the data to several theoretical models on the origin of early excess flux in SNe Ia. Interaction with either the companion star or close-in circumstellar material is expected to produce a faster evolution than observed. Radioactive material in the outer layers of the ejecta, either from double detonation explosion or from a 56Ni clump near the surface, cannot fully reproduce the evolution either, likely due to the sensitivity of early UV observable to the treatment of the outer part of ejecta in simulation. We conclude that no current model can adequately explain the full set of observations. We find that a relatively large fraction of nearby, bright SNe Ia with high-cadence observations have some amount of excess flux within a few days of explosion. Considering potential asymmetric emission, the physical cause of this excess flux may be ubiquitous in normal SNe Ia.

Thinning increases forest ecosystem carbon stocks

Thinning, a major measure of forest management, is known to alter carbon sequestration by affecting the forest microclimate and soil environmental conditions. However, how thinning effect on forest ecosystem carbon stocks have presented inconsistent results. Therefore, we conducted 1776 pairs of thinning experiment observations worldwide to explore how thinning affects forest vegetation and soil carbon stocks. The results showed that overall thinning significantly increased total tree aboveground biomass carbon stocks (AGCtotal, +23.9%, +1.3 Mg ha-1 yr-1), understory vegetation carbon stocks (UVC, +68.3%, 0.12 Mg ha-1 yr-1), and soil organic carbon stocks (SOCstocks, +4.8%, 1.0 Mg ha-1 yr-1) at the global, but exhibited significantly decreased carbon stocks of litterfall (LBC, –9.6%, –0.03 Mg ha-1 yr-1). Belowground biomass carbon stocks remained unchanged under thinning. The sensitivity of carbon sequestration to thinning gradually disappeared after 6 years, except for AGCtotal, as they were jointly subject to stand density and thinning intensity and not just recovery ages. The response to UVC was more positive in medium-density (1500 – 3000 trees ha-1) and moderately thinned (30 – 50%) stands, and the thinning effects on UVC and SOCstocks were more noticeable in the subtropical and temperate zones. In summary, thinning enhanced forest ecosystem carbon sinks (+2.4 Mg ha-1 yr-1) but reduced carbon stocks in low-density stands (≤ 1500 trees ha-1). Soil moisture content (SMC, +6.6%) and bulk density (BD, –1.5%) dynamics after thinning were important factors regulating vegetation growth and soil carbon cycling processes.

An experimental and modeling study on homogeneous oxidative coupling of methane utilizing N2O as oxidant

Experimental and kinetic modeling studies were performed to investigate the homogeneous oxidative coupling of methane utilizing nitrous oxide as the oxidant (N2O-OCM). The experiments were performed in a jet stirred reactor at atmospheric pressure and temperatures of 773–1173 K. Synchrotron vacuum ultraviolet photoionization mass spectrometry was used to achieve comprehensive and isomer-resolved identification of major products and nitrogenous, carbonyl and hydrocarbon intermediates. To interpret the experiments, a detailed kinetic model was developed by extending the widely used hydrocarbon growth mechanisms. Rate of production and sensitivity analyses were performed to provide a deep insight into the complex reaction network. The results demonstrate that N2O dissociation is the rate-controlling step, and the mild oxidation of N2O effectively reduces the production of CO2 as byproduct and meanwhile improves the selectivity of C2 species. In the presence of N2O, CH3 can actively participates in H-abstraction reactions of C2H6 and C2H4, besides the self-coupling reactions. Due to chain-propagation competition reactions (N2O+H=N2+OH and N2O+H=NH+NO), NH3 and NO exhibit low concentrations. The detailed formation pathways for NH3 and NO were elaborated, and the evolution routes of carbonyl intermediates in the presence of N2O were analyzed. Benzene formation is found mainly through C3 self-recombination and C5 ring reforming reactions. Finally, comparative analysis with O2-OCM reveals that the presence of oxygen promotes the conversion of CH3 to CH2O and deep oxidation of C2H3, explaining the lower C2 yield of O2-OCM. The inherent limitation of the C2 yield of N2O-OCM primarily arises from the reaction of C2H4 and O, as well as the subsequent reaction CH2(S)+N2O=CH2O+N2. The experiment observations confirmed the existence of C2 carbonyl intermediates such as ketene and acetaldehyde. The study highlights the notable role of O2 molecular and O atoms in the homogeneous OCM and offers kinetic support for the OCM reaction process with catalysts.