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Air–sea exchanges play a crucial role in intense weather events over Sri Lanka, particularly by providing the heat and moisture that fuel heavy rainfall. We present a year-round dataset of meteorological observations from the southern shoreline of Sri Lanka in the equatorial Indian Ocean for 2017, aiming to investigate its seasonal characteristics and evaluate the performance of reanalysis data in this region. The observations reveal distinct diurnal and seasonal patterns. During the winter and spring, higher shortwave (646.2 W/m2) and longwave radiation (−86.9 W/m2) are coupled with higher temperatures (30.6 °C) and lower humidity (67.4% at noon). In contrast, the Indian summer monsoon period features reduced shortwave (579.8 W/m2) and longwave radiation (−58.6 W/m2), lower temperatures (29.2 °C), higher humidity (over 79.7%), and stronger winds (6.25 m/s). The observations were compared with the ERA5 reanalysis dataset to evaluate the regional performance. The reanalysis data correlated well with the observed data for the radiation, temperature, and sensible heat flux, although notable deviations occurred in terms of the wind speed and latent heat flux. During the impact of Tropical Cyclone Ockhi, the reanalysis data tended to underestimate both the wind speed and precipitation. This dataset will provide vital support for studies on monsoons and coastal atmospheric convection, as well as for model initialization and synergistic applications. [ABSTRACT FROM AUTHOR]

Short-time oxidation exposures of the Ni-based TROPEA single crystal superalloy was implemented to determine the nature and quantities of transient oxides in the 680–1000 °C temperature range. Experiments were carried out in situ in the SEM with reduced air pressure (150 Pa, P O 2 ~ 31.5 Pa) compared to atmospheric conditions (105 Pa, P O 2 ~ 2.1 104 Pa). TEM characterization after oxidation showed the complexity of the oxidation products developed. Aluminum underwent internal oxidation between 680 and 1000 °C. During the limited duration of oxidation, the TROPEA alloy only formed a continuous alumina layer at 1000 °C. At 680 and 850 °C, the low diffusion rate and small amount of Al in the Ni-based single crystal led to the formation of a significant amount of transient oxides such as (Ni,Co)O, compared to the desired chromia or alumina protective oxides. The lower the temperature, the smaller the size of the internal Al2O3 precipitates and the larger the transient oxide amount, which would lower the resistance of TROPEA to Type II hot corrosion. In contrast after a transient period shorter than 22 h, during which multiple transient oxide developed, the oxidation resistance would be ensured at 1000 °C by the formation of a continuous Al2O3 scale. [ABSTRACT FROM AUTHOR]

The knowledge of the deposition fate of ambient polycyclic aromatic hydrocarbons (PAHs) on plant leaves is limited. To fill in this knowledge gap, this study strives to observe the intermolecular complex between the polycyclic aromatic hydrocarbons and epicuticular wax of plant leaves using laser scanning microscopy. Epicuticular wax refers to a type of organic mixture that covers the outermost layer of leaves. The leaves of 20 tree species were collected in Beijing in July 2023. The concentrations of 31 PAHs were quantified by gas chromatography–mass spectrometry. Furthermore, the intermolecular complexes of polycyclic aromatic hydrocarbons and epicuticular wax were found with a fluorescence spectrofluorometer and laser scanning microscopy. The levels of total PAHs across 20 tree species ranged from 12.4 ng g−1 to 68.4 ng g−1. Differences in the amounts of total PAHs across tree leaves were observed, which may be ascribed to the differences in leaf surface across tree types. The higher concentration of low-molecular-weight PAHs was found in leaves compared to high-molecular-weight PAHs. The fluorescence spectrofluorometer identified the formation of a new intermolecular complex with fluorescence emission at an excitation wavelength of 340 nm between PAHs and epicuticular wax relative to PAHs. We used laser scanning microscopy with a 405 nm laser for excitation to observe the new intermolecular complex of PAHs and epicuticular wax on the stomata and epicuticular wax of leaves. This study found the intermolecular complex of PAHs on the surface of leaves in situ, which provides important information about the deposition fate of ambient PAHs. [ABSTRACT FROM AUTHOR]

We deployed 8 surface drifters in the western North Pacific in 2022. By integrating the Global Drifter Program's data, we analyzed the drifter-based sea surface currents and temperatures during tropical cyclones. The maximum in-situ surface current observed was 0.70 m/s during typhoon Hinnamnor. Our surface drifters provided similar observations as compared to an adjacent Global Drifter Program's drifter. Furthermore, we investigated float profiling observations during tropical cyclones. Based on Argo float 2903647, the SST decreased by 1.4°C after the passage of typhoon Hinnamnor. This study demonstrates the reliability of our newly deployed surface drifters and exhibits the state-of-the-art capability for in-situ observations of tropical cyclone-ocean interaction. [ABSTRACT FROM AUTHOR]

In Earth's crust, thermochemical sulfate reduction (TSR) is a common organic–inorganic interaction, which is in close association with the carbon cycle in sedimentary basins and metal sulfide precipitation in Mississippi Valley-type deposits. However, the reaction pathway and mechanism of TSR need further investigation, mainly due to the complex sulfur species involved in this reaction. Here we applied in situ Raman spectroscopy to disclose the stepwise transformation from sulfate to sulfide and the reaction kinetics in the CH 4 -Na 2 SO 4 /MgSO 4 /H 2 SO 4 -H 2 O systems at elevated temperatures and pressures. Our results indicate that sulfate is transformed to H 2 S through a series of reduction and disproportionation reactions. Once dissolved H 2 S reaches a certain concentration, it reacts with sulfate to form intermediate valence sulfur species (S0 and S 3 −), which quickly oxidize methane to generate CO 2 and H 2 S. The formation of S 3 − and S0 is responsible for the autocatalytic effect in TSR. The sulfur speciation significantly affects the reaction kinetics, which could be divided into three stages based on the in situ observations. Extrapolated kinetic data show that TSR could proceed fast under the catalysis of H 2 S, and the half-life of methane is ∼7.10 million years at 200 °C. Subsequent numerical modeling strongly supports that in situ sulfate reduction could provide sufficient reduced sulfur for the formation of giant Mississippi Valley-type deposits, thus serving as an efficient mineralizing mechanism. [ABSTRACT FROM AUTHOR]

The ultrafine cellular structure promotes the extraordinary mechanical performance of metals manufactured by laser powder‐bed‐fusion (L‐PBF). An in‐depth understanding of the mechanisms governing the thermal stability of such structures is crucial for designing reliable L‐PBF components for high‐temperature applications. Here, characterizations and 3D discrete dislocation dynamics simulations are performed to comprehensively understand the evolution of cellular structures in 316L stainless steel during annealing. The dominance of screw‐type dislocation dipoles in the dislocation cells is reported. However, the majority of dislocations in sub‐grain boundaries (SGBs) are geometrically necessary dislocations (GNDs) with varying types. The disparity in dislocation types can be attributed to the variation in local stacking fault energy (SFE) arising from chemical heterogeneity. The presence of screw‐type dislocations facilitates the unpinning of dislocations from dislocation cells/SGBs, resulting in a high dislocation mobility. In contrast, the migration of SGBs with dominating edge‐type GNDs requires collaborative motion of dislocations, leading to a sluggish migration rate and an enhanced thermal stability. This work emphasizes the significant role of dislocation type in the thermal stability of cellular structures. Furthermore, it sheds light on how to locally tune dislocation structures with desired dislocation types by adjusting local chemistry‐dependent SFE and heat treatment. [ABSTRACT FROM AUTHOR]

The dynamic behavior of nonmetallic inclusions at the bubble–steel interface is a key factor contributing to the formation of large‐sized inclusions or clustered particles and is particularly important for the production of high‐quality‐oriented silicon steel. In this study, high‐temperature confocal laser scanning microscopy is employed for in situ observation of the agglomeration behavior of Al2O3 inclusions of varying sizes. The critical distance of attraction decreases with the decrease in inclusion size. The effects of particle size, distance, surface tension, density, and different types of inclusions on the capillary force are explored in detail using the Kralchevsky–Paunov model. In the model results, it is highlighted that the degree of influence among the factors affecting the capillary force decreases in the following order: contact angle > size > distance > density > surface tension. Furthermore, the observed results are compared with the model calculation results. The trends of the model calculations and the experimental results show good agreement, but most of the experimental values are higher than the theoretical values. The errors primarily stem from inclusion shape, interference from other inclusion forces, and interactions between the crucible wall and inclusions. [ABSTRACT FROM AUTHOR]

Herein, a 3D stability diagram is established in the AlON system. Based on that, four sets of experiments with different Al contents are designed to prepare different inclusions. Subsequently, the agglomeration behavior of inclusion is observed in situ by using confocal laser scanning microscopy (CLSM) combined with an infrared image furnace. The sample with inclusions is heated to melt and the agglomeration behavior of inclusion is recorded by the CRT monitor of CLSM. The calculated agglomeration force of inclusion shows that when the Al content increases from 0.5 to 3 pct, the agglomeration force of Al2O3 inclusions decreases from 7.2 × 10−16 ≈ 6.0 × 10−14 N to 1.2 × 10−16 ≈ 3.2 × 10−15 N. As the Al content increases from 6.5 to 10 pct, the agglomeration force of AlN inclusions increases from 2.2 × 10−17 ≈ 1.1 × 10−15 N to 1.7 × 10−16 ≈ 7.9 × 10−15 N. The theoretical calculation also shows that the agglomeration force of Al2O3 inclusions decreases and that of AlN inclusions increases with the increasing Al content. When the Al content is >4.7 pct, the agglomeration force of AlN inclusions is larger than that of Al2O3 inclusions. [ABSTRACT FROM AUTHOR]

Castor oil has attracted large attention for wide applications, including lubrication oil and bioenergy resources. Castor seeds mechanical pressing is widely used for oil extraction. To better research castor seeds mechanical‐structural damage behavior and oil extraction mechanism during extrusion, a self‐developed mechanical pressing test setup combined with in situ observation is built for oil output behavior. Influencing factors of working pressure, speed, temperature and creep time on oil outflow were investigated. The results indicate that seeds squeezing extraction can be divided into three stages, preloading, oil discharging, compressing consolidation stage, matching with pressing cake structural evolution. As working pressure increases, oil yield shows an upper parabola relation with pressure. When pressure exceeding 25 MPa, castor oil yield increasing tends to stabilize, reaching 38%. Speed effect showed down parabola relation on oil yield, opposite to stress factor. Creep time promoted oil output with upper parabola within 720 s. When temperature below 120°C, a linear increasing relation on oil yield presents. Oil yield decreases when above 120°C. This research provides in‐depth theoretical guidance for industrial castor oil extraction. Practical Applications: Castor seeds are rich in oil content. Extracted castor oil has been widely used for industrial applications such as biodiesel, lubricants, medicine. Mechanical extraction working parameters optimization can improve oil yield of castor seeds. The research provides a basic working optimization for castor seeds oil extraction. Castor oil has unique properties and has been proved to be a high promising renewable and independent energy sources. Compared with solvent oil extraction, mechanical oil pressing extraction method has higher oil quality and safety. The mechanical extracted oil is pure without organic solvent. In the research, castor seeds compression‐structural damage property and oil extraction mechanism were studied. Besides, the influence factors including compression pressure, speed, temperature and creep time are analyzed, working optimization for castor seeds oil extraction. The research provides important reference value for the mechanical pressing process and mechanical design of castor seeds in the practical applications. [ABSTRACT FROM AUTHOR]

Gravity wave (GW) momentum flux spectra help to uncover the mechanisms through which GWs influence momentum transfer in the atmosphere and provide crucial insights into accurately characterizing atmospheric wave processes. This study examines the momentum flux spectra of GWs in the troposphere (2–14 km) and stratosphere (18–28 km) over Koror Island (7.2°N, 134.3°W) using radiosonde data from 2013–2018. Utilizing hodograph analysis and spectral methods, the characteristics of momentum flux spectra are discussed. Given that the zonal momentum flux spectra of low-level atmospheric GWs generally follow a Gaussian distribution, Gaussian fitting was applied to the spectral structures. This fitting further explores the seasonal variations of the zonal momentum flux spectra and the average spectral parameters for each month. Additionally, the GW energy is analyzed using SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) satellite data and compared with the results of the momentum flux spectra from radiosonde data, revealing the close negative correlation between wave energy and wave momentum for stratospheric GW changing with time. The findings indicate that the Gaussian peak shifts more eastward in both the troposphere and stratosphere, primarily due to the absorption of eastward-propagating GWs by the winter tropospheric westerly jet and critical layer filtering. The full width at half maximum (FWHM) in the stratosphere is larger than in the troposphere, especially in June and July, as the spectrum broadens due to propagation effects, filtering, and interactions among waves. The central phase speed in the stratosphere exceeds that in the troposphere, reflecting the influences of Doppler effects and background wind absorption. The momentum flux in the stratosphere is lower than in the troposphere, which is attributed to jet absorption, partial reflection, or the dissipation of GWs. [ABSTRACT FROM AUTHOR]

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Large-sized titanium-containing inclusion clusters seriously affect the continuous casting and performance of high titanium wear-resistant steel. In the current work, thermodynamic calculations were firstly conducted to predict the formation of various complex TiN inclusions, viz, TiOx-TiN, Al2O3–TiN and LaAlO3–TiN. Based on that, laboratory-scale experiments were designed to prepare samples containing a single type of complex TiN inclusions. The agglomeration characterizes of different complex inclusions were compared by combing in-situ observation based on confocal laser scanning microscopy and Newtonian motion equation. Furthermore, the Kralchevsky-Paunov model was used to study the influences of density and size on the agglomeration behavior of complex TiN inclusions. The result shows that the attractive force between TiOx-TiN complex inclusions increases from 1.93 × 10−18 to 4.34 × 10−17 N, while it was 3.41 × 10−17 to 5.12 × 10−16 N for Al2O3–TiN complex inclusions and 6.42 × 10−18 to 1.14 × 10−16 N for LaAlO3–TiN inclusions. Based on the experimental results and theoretical calculation, the agglomeration tendency of Al2O3–TiN is the strongest due to the considered size and compared to the TiOx-TiN inclusions, the stronger agglomeration tendency of LaAlO3–TiN ones can be attributed to their higher density.

Atmospheric aerosols not only cause severe haze pollution, but also affect climate through changes in cloud properties. However, during the haze pollution, aerosol‐cloud interactions are not well understood due to a lack of in situ observations. In this study, we conducted simultaneous observations of cloud droplet and particle number size distribution, together with supporting atmospheric parameters, from ground to cloud base in East China using a high‐payload tethered airship. We found that high concentrations of aerosols and cloud condensation nuclei were constrained below cloud, leading to the pronounced "Twomey effect" near the cloud base. The cloud inhibited the pollutants dispersion by reducing surface heat flux and thus deteriorated the near‐surface haze pollution. Satellite retrievals matched well with the in situ observations for low stratus clouds, while were insufficient to quantify aerosol‐cloud interactions for other cases. Our results highlight the importance to combine in situ vertical and satellite observations to quantify the aerosol‐cloud interactions. Plain Language Summary: Atmospheric aerosols, one of the major pollutants contributing to air pollution, also play an important role in climate through their interactions with clouds. The impact of aerosols on cloud properties remains the largest uncertainty in climate projections, partly due to a lack of in situ observations. Here, we conducted simultaneous observations on atmospheric aerosols and clouds from ground to 1,200 m above ground level in East China using a high‐payload tethered airship. We found aerosols number concentration was high below the clouds, which increased the cloud droplet concentration and decreased the cloud droplet diameter near cloud base. The clouds deteriorated the near‐surface air pollution, thus increasing exposure to hazardous levels. For low stratiform clouds, the satellite retrievals matched well with the observations, suggesting the satellite observation is a powerful tool to investigate clouds. However, the aerosol‐cloud interactions can still be underestimated by satellite measurements as the satellites record cloud properties near cloud top. We emphasize the need for direct in situ observations from the ground to high altitudes to quantify the effects of aerosols on cloud properties. Key Points: The pronounced Twomey effect near the cloud base was directly observed during the haze pollution by the tethered airship measurementThe observed Twomey effect at the cloud base in East China contradicts the satellite‐detected anti‐Twomey effect at the top of cloudsSatellite retrieved cloud effective radius is comparable to observation near cloud base of low stratus clouds, while is biased for others [ABSTRACT FROM AUTHOR]

We have obtained straight-line-shaped agglomeration grooves of 2~3.5 μm width in the ~60-nm-thick Si thin films by the continuous-wave laser crystallization (CLC) when the laser power is increased above the optimum power to obtain grain boundary-free (GB-free) films. The GB-free CLC is suitable for fabricating monolithic three-dimensional integrations. The grooves are formed in the Si film vertically from the Si surface to the underlying insulating substrate, and a hump of the Si film is generated along the edge of the groove at the retarded side of the scan. In situ observation of the crystal growth shows that the grooves originate from voids, which happen to be generated by agglomeration in the melt zone. The voids move at a constant velocity, Vvoid , within the melt zone. The melt zone moves at the scan velocity, V, to the scan direction. The void velocity, Vvoid , is obtained from the angle of the groove line to the scan direction, and is found to be proportional to V−0.5. [ABSTRACT FROM AUTHOR]

In this paper, the influence of bismuth content and heating rate on the morphology of MnS inclusions in bismuth-containing free-cutting steel during heating was investigated through in situ observation experiments and 3D electrolytic corrosion experiments. By observing the microscopic morphology of inclusions in the original sample, it was found that MnS inclusions in the sample were rod-shaped, spherical, irregular, small in size, and mostly clustered at the grain boundary in the form of chains and divergences. With the addition of bismuth, MnS inclusions of a larger size appear in the steel, and the inclusions distributed at grain boundaries are also reduced. When bismuth (0.010~0.020%) is added to the steel, MnS is mainly spherical and uniformly dispersed in the steel matrix. If the bismuth content is too high, the inclusions aggregate. Through in situ observations of the inclusions in the sample, it was found that the addition of bismuth in the heating process delays the appearance of ferrite grain boundaries and contributes to the spheroidization of MnS inclusions. Mn and S elements can fully diffuse slowly in the matrix with a heating rate below 1 °C/s and a long holding time (300 s), which provides the possibility for the spheroidization of MnS inclusions. [ABSTRACT FROM AUTHOR]

In situ observation of the decomposition process of woodchips (cedar and Quercus acutissima) in subcritical- and supercritical water was performed by neutron imaging experiment. The woodchips and D2O were sealed into a stainless tube, and the tube was heated up to 500 °C by a block heater designed for neutron imaging. The neutron imaging experiment was performed in energy-resolved neutron imaging system (RADEN) of Japan Proton Accelerator Research Complex Material and Life Science Experimental Facility (J-PARC MLF). The decomposition processes of the woodchips in D2O solvent were visualized clearly in time-lapse images. The outside of the woodchips was partially broken at 300 °C. The woodchips have a porous structure at 450 °C, and D2O penetrates the pores. The skeleton of the woodchips remains even at 500 °C. The present study clarified the optimal temperature in the decomposition process to observe the status of the woodchips during the decomposition process. It has an advantage compared with a time-consuming of the batch process. It will be useful for the development of biomass processing technology using high-temperature and high-pressure water. [ABSTRACT FROM AUTHOR]

In‐situ observations of hydrodynamics and suspended sediment concentrations (SSCs) were conducted on an abandoned lobe in the northern part of the modern Yellow River Delta, China. The SSC record at the site is found to be the superposition of a general trend (fast increase and slow decrease cycle) caused by storm waves (SubSSC1) and relatively smaller fluctuations caused by tidal currents (SubSSC2). Physically, this indicates that storm waves eroded the bottom sediments while tidal currents then re‐suspended and advected the suspended sediments in the study area. To further obtain the suspended sediment transport parameters, first, SubSSC1 is modeled with significant wave height which incorporates a "memory curve" to consider the remaining impacts of historical waves. It is detected that waves in the past 75 hr still influence the present SSC which is reasonable because 75 hr is roughly the typical duration of a normal storm. Second, SubSSC2 is modeled with tidal excursion and trigonometric functions with measured periodicities. Finally, some sediment transport parameters, for example, the background SSC, the horizontal SSC gradient, the tidal constituents that advect it, and their relative time lags are optimized from the best fits of the measured and modeled SSC time series. The proposed framework for model construction and parameter optimization can be extended to other sea areas for inferring sediment transport parameters from field SSC time series at a specific station. Plain Language Summary: The evolution of our coastal zone fundamentally depends on the transport volume and direction of sediment, and understanding them is very beneficial for our coastal engineering construction and long‐term planning. Conducting in situ observations on‐site is one of the most reliable methods, but its observation cost is expensive. Therefore, we hope to extract as much information as possible from as few observation points as possible. This article successfully extracted the above information from the observation data of a station. First, we analyzed the data to preliminarily clarify that the suspended sediment in the area mainly comes from local erosion resuspension and advection transport from other regions. Furthermore, we conducted data modeling (i.e., constructed mathematical expressions of suspended sediment components from different sources, but with undetermined coefficients). Finally, we adjusted the model parameters to approximate the measured results, determined the undetermined coefficients, and explained the practical significance of the undetermined coefficients in physics. The analysis method we proposed can be extended to other sea areas. Key Points: Storm wave‐induced suspended sediment concentration (SSC) variation is modeled with a "memory curve" of wave heightTidally‐induced SSC variation is modeled with tidal excursion and trigonometric functionsSediment transport parameters are estimated from the optimal matching of measured and modeled SSC time series [ABSTRACT FROM AUTHOR]

Abstract The ultrafine cellular structure promotes the extraordinary mechanical performance of metals manufactured by laser powder‐bed‐fusion (L‐PBF). An in‐depth understanding of the mechanisms governing the thermal stability of such structures is crucial for designing reliable L‐PBF components for high‐temperature applications. Here, characterizations and 3D discrete dislocation dynamics simulations are performed to comprehensively understand the evolution of cellular structures in 316L stainless steel during annealing. The dominance of screw‐type dislocation dipoles in the dislocation cells is reported. However, the majority of dislocations in sub‐grain boundaries (SGBs) are geometrically necessary dislocations (GNDs) with varying types. The disparity in dislocation types can be attributed to the variation in local stacking fault energy (SFE) arising from chemical heterogeneity. The presence of screw‐type dislocations facilitates the unpinning of dislocations from dislocation cells/SGBs, resulting in a high dislocation mobility. In contrast, the migration of SGBs with dominating edge‐type GNDs requires collaborative motion of dislocations, leading to a sluggish migration rate and an enhanced thermal stability. This work emphasizes the significant role of dislocation type in the thermal stability of cellular structures. Furthermore, it sheds light on how to locally tune dislocation structures with desired dislocation types by adjusting local chemistry‐dependent SFE and heat treatment.

Micro-scale corrosion imaging in conjunction with electrochemical potential noise (EPN) provides a promising, comprehensive corrosion monitoring technique that can precisely visualise specific aspects of corrosion activity. In this work, rapid, economical, and real-time monitoring through a self-designed device, captured simultaneously with the electrochemical potential and micrographs, was employed to analyse the corrosion activity of H57 brass in an HCl solution using the gray-level co-occurrence matrix (GLCM). Conducted simultaneously in the time-frequency domain, the continuous wavelet transform (CWT) analysis of the electrochemical potentials and image features shows EPN fluctuations corresponding to feature noises. Similarly, the consistency of them in-situ Brass corrosion in the HCl solution, as revealed through a nonlinear autoregressive exogenous (NARX) neural network. The results indicate that the image features extracted by GLCM can quantify the changes in corrosion images and correspond to the corrosion behaviour of brass. Notably, the anomalous peaks of feature noises accompany or lag behind EPN. Leveraging these image features, the optimized NARX model demonstrates a high predictive capability for EPN. These findings are expected to guide future corrosion monitoring techniques and even enable corrosion prediction via micron-scale corrosion images.

Highlights Digital holography can realize the in situ observation of electrode/electrolyte interface and provide dynamic evolution information of the liquid phase of electrode, which is both efficient and effective in investing the interficial electrochemical mechanism and screening electrolyte additives. Thioacetamide electrolyte additive effectively enhances the electrochemical performance of Zn anode by regulating the interficial ion flux to induce dendrite-free Zn deposition and constructing adsorption molecule layers to inhibit side reactions.

An experimental investigation has been conducted with respect to the decomposition of austenite to various ferritic products from different initial phase states (molten-state of 1550 °C and solid-state of 1050 °C) and pre-defined cooling rates (1 °C/s and 10 °C/s) in a typical low-carbon steel using the confocal laser scanning microscope (CLSM). Surface morphology, microstructure, internal stress and dislocation density were analyzed. Changing the initial states from the molten to the solid state and lowering the cooling rate from 10 °C/s to 1 °C/s increased the phase transformation starting temperature. Compared with the uniform cooling condition to produce polygonal ferrite of the solid-state sample, unevenly distributed internal stresses were found from the initial molten-state sample. Additionally, high dislocation densities were observed in stress concentrated areas of the initial molten-state samples resulting in the formation of lath-like ferrite but coarse quasi-polygonal ferrite in relatively stress-free areas. Moreover, when the cooling rate was increased to 10 °C/s, the proportion of lath-like ferrite obviously increased in the molten-state and the size of the polygonal ferrite decreased in the solid-state sample due to the increasing of nucleation rate from austenite to ferrite.

Air–sea exchanges play a crucial role in intense weather events over Sri Lanka, particularly by providing the heat and moisture that fuel heavy rainfall. We present a year-round dataset of meteorological observations from the southern shoreline of Sri Lanka in the equatorial Indian Ocean for 2017, aiming to investigate its seasonal characteristics and evaluate the performance of reanalysis data in this region. The observations reveal distinct diurnal and seasonal patterns. During the winter and spring, higher shortwave (646.2 W/m2) and longwave radiation (−86.9 W/m2) are coupled with higher temperatures (30.6 °C) and lower humidity (67.4% at noon). In contrast, the Indian summer monsoon period features reduced shortwave (579.8 W/m2) and longwave radiation (−58.6 W/m2), lower temperatures (29.2 °C), higher humidity (over 79.7%), and stronger winds (6.25 m/s). The observations were compared with the ERA5 reanalysis dataset to evaluate the regional performance. The reanalysis data correlated well with the observed data for the radiation, temperature, and sensible heat flux, although notable deviations occurred in terms of the wind speed and latent heat flux. During the impact of Tropical Cyclone Ockhi, the reanalysis data tended to underestimate both the wind speed and precipitation. This dataset will provide vital support for studies on monsoons and coastal atmospheric convection, as well as for model initialization and synergistic applications.

This study proposes a method for estimating river plume length from water levels and river discharge rates. A numerical model for coastal ocean dynamics was refined by comparing thermohaline fields calculated using the model with those measured off the mouth of the Sakawa River in Sagami Bay, Japan. The model successfully captured the reduction in salinity within the surface 1.0-m layer caused by riverine water transport. The simulated surface salinity maps revealed that the dynamic motions of the river plumes were primarily driven by one of the two diurnal occurrences of tidal current intensification. Regression analyses of the simulated results demonstrated that the river plume lengths were closely correlated with the water levels and river discharge rates, and that they could be accurately estimated from preceding river discharge rates under weak wind condition. [ABSTRACT FROM AUTHOR]

The in-pipe robot is the most commonly used technique in offshore pipelines. The use of rubber sealing discs is important for in-pipe robots to ensure that the robots are moved by fluid pressures inside offshore pipelines. This paper focuses on the measuring and modeling of the wax–oil gel-breaking process at the soft frictional area between sealing discs and the pipe wall. In this study, a detailed characterization of the gel-scraping process and in situ probing portable microscopy are performed. Two contributions are made in this study. First, a direct observation of wax–oil deposition breaking is employed to detect the minute changes at the in-pipe robot. Second, we find that a simple function is possible to describe the relationship between the wax contents and dewaxing efficiency, in which the debris material removal ratio (DRR) is discussed. Thus, the gel deposition-breaking phenomena are quite different under the influence of rubber sealing discs. This result is further confirmed by the real contact ratio measurements. It is important to research the sealing disc further and apply it more in the petroleum industry, especially in in-pipe robots for deepwater pipeline systems. [ABSTRACT FROM AUTHOR]

Air‐sea exchanges across oceanic fronts are critical in powering cloud formation, precipitation, and atmospheric storms. Oceanic submesoscale fronts of scales 1–10 km are characterized by strong sea surface temperature (SST) gradients. However, it remains elusive how submesoscale fronts affect the overlying atmosphere due to a lack of high‐resolution observations or models. Based on rare high‐resolution in situ observations in the Kuroshio Extension region, we quantify the air‐sea exchanges across an oceanic submesoscale front. The cross‐front SST and turbulent heat flux gradients reaches 2.4°C/km and 47 W/m2/km, respectively, far stronger than that typically found in mesoscale‐resolving products. The stronger SST gradient drives substantially stronger air‐sea fluxes and vertical mixing than mesoscale fronts, enhancing cloud formations. The intense air‐sea exchanges across submesoscale fronts are confirmed in idealized model simulations, but not resolved in mesoscale‐resolving climate models. Our finding provides essential knowledge for improving simulations of cloud formation, precipitation, and storms in climate models. Plain Language Summary: Oceanic fronts, characterized by large sea surface temperature (SST) gradients, are ubiquitous in the global ocean. Through intense heat and moisture release, these oceanic fronts induce large horizontal gradient of sea level pressure or increasing vertical mixing intensity in the lower atmosphere, are critical in powering cloud formation, precipitation, and atmospheric storms, but are sensitive to SST gradients. Oceanic submesoscale fronts of spatial scales 1–10 km are characterized by strong SST gradients. However, our knowledge of how the submesoscale fronts affect the overlying atmosphere is by and large void, due to a lack of high‐resolution observations or models. Here, based on high‐resolution in situ observations and model simulations, we show that submesoscale fronts drive much stronger air‐sea exchanges and vertical mixing as compared to mesoscale fronts, with significant implications for marine atmosphere boundary layer changes and cloud formations. Limited by the coarse resolution, the intense air‐sea exchanges across submesoscale fronts are not resolved in mesoscale‐resolving climate models. These results highlight the importance of submesoscale air‐sea interactions and call for a proper representation of submesoscale air‐sea exchanges in the next generation of climate models. Key Points: Observations show strong gradient in sea surface temperature and turbulent heat flux across a submesoscale oceanic frontSubmesoscale fronts drive substantially stronger air‐sea fluxes and vertical mixing than mesoscale frontsThe intense air‐sea exchanges across submesoscale fronts are not resolved in mesoscale‐resolving climate models [ABSTRACT FROM AUTHOR]

The highly Alfvénic fluctuations (AF) and magnetic-velocity alignment structures (MVAS) are two distinguished components in the near-Sun slow solar wind observed by Parker Solar Probe. The amplitudes of the Elsäser Variables z± of AF and MVAS show distinct features. However, how these fluctuations contribute to the slow solar wind turbulence remains unknown. Here we investigate the coherence between z+ and z- for the first time using the Parker Solar Probe measurements with a high resolution 0.8738 s in the slow solar wind from 0.1-0.3 au. We find that the coherence spectra of z+ and z- in the perpendicular directions for MVAS are remarkable higher than that for AF, in particular at large scale. There exists a break around 10 di (di is the ion inertial length) where the coherence decreases to a lower level for MVAS. A bump around 10 di appears on the coherence spectra of all three components for AF. The coherence of z+ and z- may relate to the possible nonlinear interactions reflected by the time series, the power spectra, and the self-correlation functions. These results help to understand the roles of AF and MVAS in the slow solar wind turbulence. [ABSTRACT FROM AUTHOR]

Using the Arase and Van Allen Probes satellite observations, we investigate the nonlinear electromagnetic ion cyclotron (EMIC) rising‐tone (RT) emissions with an increase of the solar wind dynamic pressure in the dayside magnetosphere. We find that EMIC RT emissions are accompanied by the extended dayside uniform zone (DUZ) over |MLAT| < 25° due to the dayside magnetospheric compression by an increase in Pdyn. Using the observed plasma and magnetic field data, we modeled the threshold amplitude for the nonlinear EMIC waves and compared it with the observation. The small gradient of the ambient magnetic field strongly contributes to the reduction in the threshold amplitude of nonlinear wave growth compared to other parameters. When the threshold amplitude falls to comparable level of pre‐existing EMIC waves, EMIC RT emissions are immediately triggered, suggesting direct evidence that the DUZ is the preferred condition to cause the nonlinear EMIC RT emission in the dayside magnetosphere. Plain Language Summary: Electromagnetic ion cyclotron (EMIC) waves play an important role in controlling the dynamics of charged particles in the inner magnetosphere. Especially, nonlinear EMIC rising‐tone (RT) emissions can cause the rapid loss of relativistic electrons and ring current ions. Here, we present direct evidence demonstrating that the distortion of the dayside magnetic field causes nonlinear EMIC RT emission in response to the intensification of the solar wind dynamic pressure. Remarkably, these nonlinear EMIC waves are generated through a reduction in the threshold wave amplitudes by the distortion of the magnetic fields, even in the absence of any significant change in the pre‐existing EMIC wave amplitude. The present result provides new insights into a triggering process of nonlinear plasma waves in the magnetosphere. Key Points: Electromagnetic ion cyclotron (EMIC) waves with rising‐tone (RT) elements were observed in the dayside magnetosphere during an increase in the solar wind dynamic pressureIncreasing solar wind dynamic pressure extends the dayside uniform zone of the magnetic field to higher magnetic latitudesThe uniform zone leads to the reduction of the nonlinear threshold wave amplitude, which triggers nonlinear EMIC RT emissions [ABSTRACT FROM AUTHOR]

Abstract Atmospheric aerosols not only cause severe haze pollution, but also affect climate through changes in cloud properties. However, during the haze pollution, aerosol‐cloud interactions are not well understood due to a lack of in situ observations. In this study, we conducted simultaneous observations of cloud droplet and particle number size distribution, together with supporting atmospheric parameters, from ground to cloud base in East China using a high‐payload tethered airship. We found that high concentrations of aerosols and cloud condensation nuclei were constrained below cloud, leading to the pronounced “Twomey effect” near the cloud base. The cloud inhibited the pollutants dispersion by reducing surface heat flux and thus deteriorated the near‐surface haze pollution. Satellite retrievals matched well with the in situ observations for low stratus clouds, while were insufficient to quantify aerosol‐cloud interactions for other cases. Our results highlight the importance to combine in situ vertical and satellite observations to quantify the aerosol‐cloud interactions.

The knowledge of the deposition fate of ambient polycyclic aromatic hydrocarbons (PAHs) on plant leaves is limited. To fill in this knowledge gap, this study strives to observe the intermolecular complex between the polycyclic aromatic hydrocarbons and epicuticular wax of plant leaves using laser scanning microscopy. Epicuticular wax refers to a type of organic mixture that covers the outermost layer of leaves. The leaves of 20 tree species were collected in Beijing in July 2023. The concentrations of 31 PAHs were quantified by gas chromatography–mass spectrometry. Furthermore, the intermolecular complexes of polycyclic aromatic hydrocarbons and epicuticular wax were found with a fluorescence spectrofluorometer and laser scanning microscopy. The levels of total PAHs across 20 tree species ranged from 12.4 ng g−1 to 68.4 ng g−1. Differences in the amounts of total PAHs across tree leaves were observed, which may be ascribed to the differences in leaf surface across tree types. The higher concentration of low-molecular-weight PAHs was found in leaves compared to high-molecular-weight PAHs. The fluorescence spectrofluorometer identified the formation of a new intermolecular complex with fluorescence emission at an excitation wavelength of 340 nm between PAHs and epicuticular wax relative to PAHs. We used laser scanning microscopy with a 405 nm laser for excitation to observe the new intermolecular complex of PAHs and epicuticular wax on the stomata and epicuticular wax of leaves. This study found the intermolecular complex of PAHs on the surface of leaves in situ, which provides important information about the deposition fate of ambient PAHs.

Gravity wave (GW) momentum flux spectra help to uncover the mechanisms through which GWs influence momentum transfer in the atmosphere and provide crucial insights into accurately characterizing atmospheric wave processes. This study examines the momentum flux spectra of GWs in the troposphere (2–14 km) and stratosphere (18–28 km) over Koror Island (7.2°N, 134.3°W) using radiosonde data from 2013–2018. Utilizing hodograph analysis and spectral methods, the characteristics of momentum flux spectra are discussed. Given that the zonal momentum flux spectra of low-level atmospheric GWs generally follow a Gaussian distribution, Gaussian fitting was applied to the spectral structures. This fitting further explores the seasonal variations of the zonal momentum flux spectra and the average spectral parameters for each month. Additionally, the GW energy is analyzed using SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) satellite data and compared with the results of the momentum flux spectra from radiosonde data, revealing the close negative correlation between wave energy and wave momentum for stratospheric GW changing with time. The findings indicate that the Gaussian peak shifts more eastward in both the troposphere and stratosphere, primarily due to the absorption of eastward-propagating GWs by the winter tropospheric westerly jet and critical layer filtering. The full width at half maximum (FWHM) in the stratosphere is larger than in the troposphere, especially in June and July, as the spectrum broadens due to propagation effects, filtering, and interactions among waves. The central phase speed in the stratosphere exceeds that in the troposphere, reflecting the influences of Doppler effects and background wind absorption. The momentum flux in the stratosphere is lower than in the troposphere, which is attributed to jet absorption, partial reflection, or the dissipation of GWs.

The anodic dissolution reaction of copper in copper electro-refining was studied by considering the reaction of galvanic couples with different metals as impurities. In this study, zinc was chosen as a typical anodic impurity and silver as a cathodic impurity, and electrochemical measurements of galvanic couples with silver or zinc wires winding around a copper wire and in situ observation of the electrode surface using a stereo microscope were carried out. For comparison, copper wire with zinc or silver plating was used. As a result, even the simple method of winding silver or zinc wire around copper wire was able to capture the characteristic behavior of the galvanic reaction of silver and zinc on copper wire. It was also confirmed that zinc dissolution was accelerated by copper and copper dissolution was accelerated by silver, and that the effects were more promoted under anodic polarization. The crystallization and passivation of copper sulfate on the copper electrode surface and the dissolution behavior of silver were also observed. These results indicate that the experimental method presented in this study is an effective way to investigate the effects of impurities on the solubility and passivation of crude copper metal.

Casting performance is seriously jeopardized by metallurgical defects, especially the long-neglected bifilm defects that have been found in various alloys. The theory of entrainment formation of bifilm defects has been commonly accepted, but their visualization of the formation process and fracture behavior are absent to date, which is explored in the present work. The vivid numerical simulation results showed that the rapid rise of the liquid level leads to violent melt fluctuation, which results in the repeated folding-entrainment-detachment process of the oxide film on the melt surface. Different motion trajectories would be produced by the bifilm defects based on their composition. The observation of metallographic samples confirmed the corresponding results. Meanwhile, the fracture behavior of bifilm defects can be studied using optical in situ tensile. The results show that the bifilm defects are the source of cracks, and the connection of their influence domains causes the cracks to expand laterally. These results will shed new light on the understanding of the formation and fracture process of bifilm defects and improve the defect control of castings.

Abstract Using the Arase and Van Allen Probes satellite observations, we investigate the nonlinear electromagnetic ion cyclotron (EMIC) rising‐tone (RT) emissions with an increase of the solar wind dynamic pressure in the dayside magnetosphere. We find that EMIC RT emissions are accompanied by the extended dayside uniform zone (DUZ) over |MLAT|

Abstract Air‐sea exchanges across oceanic fronts are critical in powering cloud formation, precipitation, and atmospheric storms. Oceanic submesoscale fronts of scales 1–10 km are characterized by strong sea surface temperature (SST) gradients. However, it remains elusive how submesoscale fronts affect the overlying atmosphere due to a lack of high‐resolution observations or models. Based on rare high‐resolution in situ observations in the Kuroshio Extension region, we quantify the air‐sea exchanges across an oceanic submesoscale front. The cross‐front SST and turbulent heat flux gradients reaches 2.4°C/km and 47 W/m2/km, respectively, far stronger than that typically found in mesoscale‐resolving products. The stronger SST gradient drives substantially stronger air‐sea fluxes and vertical mixing than mesoscale fronts, enhancing cloud formations. The intense air‐sea exchanges across submesoscale fronts are confirmed in idealized model simulations, but not resolved in mesoscale‐resolving climate models. Our finding provides essential knowledge for improving simulations of cloud formation, precipitation, and storms in climate models.

With the increasing demand for electric vehicles, further development of Li+ batteries require more comprehensive studies and advanced techniques to analyze various battery material and mechanisms. Determining the concentration of Li+ and electric potential inside batteries can effectively reveal and predict the electrochemical performance, understanding the charge/discharge processes and failure mechanisms. Recently, in situ observation of Li+ movement have been reported by utilizing optical microscopy, neutron imaging (NI), neutron depth profiling (NDP), and transmission electron microscopy (TEM)-based electron energy-loss spectroscopy (EELS). These extensive works suggest their broad potential applications, including revealing the spatial distribution of Li+, mapping electrode elements, and indicating degradation mechanisms. Moreover, direct visualization of potential changes through TEM-based electron holography (EH) and Kelvin probe force microscopy (KPFM) can discover and validate more valuable information. This perspective paper summarizes the current development of advanced in situ techniques for observing Li+ and potential distribution inside batteries for the first time. Additionally, we address the key challenges faced by these techniques along with their possible solutions. The aim of this paper is to provide a comprehensive discussion of in situ methods for analyzing reaction mechanisms, optimizing electrochemical performance, and potentially supporting the further development of battery simulation.

Non-equilibrium processes such as nucleation are difficult to observe in situ using transmission electron microscopy (TEM) because of spatiotemporal stochastic process. Therefore, we have been developing a method to predict/detect nucleation events and observe under low electron doses conditions in real time with the support of machine learning. Low electron dose observation is important to avoid radiolysis of water in the observation of aqueous solutions using liquid-cell TEM. Our data-driven TEM that can suggest observation points to the operator by processing in situ observation data in real time. In other words, it is data-driven TEM in which the TEM helps the operator, rather than the TEM being driven by the data. By incorporating the two codes into the TEM's software, nucleation can now be observed efficiently. [ABSTRACT FROM AUTHOR]

We demonstrate an in situ optical observation of graphene growth on a Cu substrate during chemical vapor deposition (CVD). An optical reflection microscope with an ultraviolet (UV) light source was mounted on a conventional CVD setup with a hot-wall chamber. The optical reflection of graphene largely changed at wavelengths of around 270 nm, which is attributed to an interband optical transition at the M point in the Brillouin zone of graphene. As a result, the in situ observation in the UV region gives stronger image contrast than that in visible regions. Moreover, the imaging with the UV light source is not influenced by strong thermal radiation in the visible and infrared regions from the hot-wall chamber heated to a growth temperature of around 1050 °C. We also show that the number of graphene layers can be distinguished from the image contrast. This in situ observation captures a series of growth processes from the early stage of graphene domain formation to grain growth and film formation in a single experiment and provides more detailed growth features compared to conventional ex situ evaluations. Our in situ observation method will deepen our understanding of the growth mechanism as well as improve controllability and reproducibility in real time to obtain high-quality graphene, thus making it useful for industrial process. [ABSTRACT FROM AUTHOR]

Although evolution dynamic investigation onto electrochemically generated bubbles on electrode surfaces is crucial for releasing "bubble blocking" effects, traditional "top view" or "side view" methods make spatiotemporal interfacial revolutions difficult to achieve, which are critical for a deeper understanding and better electrode design. In this study, a novel method utilizing surface plasmon resonance (SPR) is proposed to probe bubble interfacial dynamics. By monitoring reflectivity changes and utilizing differential imaging, real‐time fluctuations in the contact area can be accurately visualized. The investigation onto bubble growth events on both aerophilic and aerophobic surfaces reveals that they occur in very distinct patterns. Due to the "necking effect", the reflectivity of aerophilic electrodes rushed to its highest value and remained or gradually decreased, followed by a sudden drop due to bubble disengagement. While the aerophobic ones increased to the bubble release threshold after a downward parabola function, then dropped abruptly without plateau. This in situ imaging technique provides a feasible tool for bubble disengagement dynamic investigations on electrode surface. Based on current observations, it is revealed that changing the wettability of electrodes causes substantial changes in bubble evolution dynamics. [ABSTRACT FROM AUTHOR]

With the consumption of terrestrial metal resources, deep-sea polymetallic nodule minerals have been widely exploited around the world. Therefore, the environmental impact of deep-sea polymetallic nodule mining cannot be ignored. In this study, for the first time, a field disturbance and observation device, integrated with multiple sensors, is used to simulate the disturbance process of mining on seabed sediments in the polymetallic nodule area of the western Pacific Ocean at a depth of 5700 m. The impact of the process of stroking and lifting on the bottom sediment in the polymetallic nodule area is 30 times higher than that caused by the waves or the current. The time for turbidity to return to normal after the increase is about 30 min, and the influence distance of a disturbance to the bottom bed on turbidity is about 126 m. The time it takes for density to return to normal is about four hours, and the influence is about 1000 m. At the same time, the resuspension of the bottom sediment leads to an increase in density anomaly and salinity. Moreover, suspended sediments rich in metal ions may react with dissolved oxygen in water, resulting in a decrease in the dissolved oxygen content and an increase in ORP. During the observation period, the phenomenon of a deep-sea reciprocating current is found, which may cause the suspended sediment generated by the continuous operation of the mining vehicle to produce suspended sediment clouds in the water near the bottom of the mining area. This could lead to the continuous increase in nutrients in the water near the bottom of the mining area and the continuous reduction in dissolved oxygen, which will have a significant impact on the local ecological environment. Therefore, the way mining vehicles dig and wash in water bodies could have a marked impact on the marine environment. We suggest adopting the technology of suction and ore separation on mining ships, as well as bringing the separated sediment back to the land for comprehensive utilization. [ABSTRACT FROM AUTHOR]

Dynamic behavior of electrochemical interfacial phenomena is key issue for material science. Scanning probe microscope can observe the surface on the nanoscale, however, it is difficult to discuss the reaction process due to poor temporal resolution. High-speed atomic force microscopy (HS-AFM) is one of powerful in-situ observation tools. Here, we would like to introduce the HS-AFM applications for electrochemistry, such as Cu electrodeposition, polyethylene glycol (PEG) adsorption, and nanobubble electrolytic evolution by HS-AFM. [ABSTRACT FROM AUTHOR]

The process of soil drying is referred to as soil moisture drydown.It usually occurs after precipitation， especially for surface soil， and we address this process in three dominant regimes： gravity drainage， energy-limited regime and water-limited regime.The Heihe River Basin originates from the Qilian Mountains， and the landscape zonality here is clear from its upstream， midstream and downstream.By exploring the characteristics of surface soil moisture drydown in this area， researchers were able to understand the patterns and factors associated with soil evaporation under different conditions.The soil drydown events were investigated using data on soil moisture， soil temperature， and air temperature collected between 2016 and 2020 from 10 meteorological observation stations located in the Heihe River Basin.The relationships between soil moisture （SM）， potential evaporation （PE）， the normalized difference vegetation index （NDVI）， soil texture and surface soil drying rates were explored.Using the exponential model for fitting drydown events， the seasonal variation of the drying rate at each site was compared.Results showed that： （1） There were 362 effective drydown episodes between 2016 and 2020， totaling 3584 days.After entering the drydown stage， as the soil gradually became dry， the drying rate also slowed down and became stable after 12 days.The upstream site settled around 0.04 cm3·cm-3·day-1， whereas the middle and downstream sites tended to 0.（2） In upstream， midstream， and downstream， the values of surface soil moisture evaporation efficiency （90%） are lower than 0.25， 0.15， and 0.12， respectively， which can only partially meet atmospheric demand.The evaporation efficiency may be close to 1 if the evapotranspiration of soil profiles below 5 cm is taken into account.（3） Because the surface soil in upstream locations of the Heihe River is relatively wet， the soil drydown process is limited by the atmosphere.The middle and lower reaches of the Heihe River are drier and limited by water.As for the surface soil evaporation rate， the upstream was mainly affected by atmospheric water demand； it increases along with PE.When SM exceeded 0.4 cm3·cm-3， PE and SM had no significant impact on soil drying rate.In the middle and downstream of the Heihe River， the soil evaporation rate increases with SM.In comparison to upstream， the impact of PE on soil evaporation rate is less significant.（4） The type of vegetation and the dry and wet states of the soil both affect how quickly the surface SM dries； the drying rate is very slightly influenced by soil texture.（5） The drydown events fitted by the exponential model have distinct season features.The highest drying rate （τ）， the highest drying range （A）， and the lowest lower limit of soil moisture （θw） were observed in summer.As for desert region， θw is more affected by precipitation and is higher in the summer.For the entire basin， the drying rate of surface soil moisture from high to low was summer， spring， autumn， and the seasonal variability of drying rate increased with the change in surface coverage （meadow， farmland， shrub）.