Deposition Density Research Articles

Investigating the association between dry deposition of cesium and different growth stages of aboveground parts of Chinese yam

Abstract Radiocesium released into the atmosphere from accidents at nuclear facilities, can be deposited on the surface of the surrounding crop fields as dry and wet deposits. Radiocesium deposition can occur at any time during the growth season. In this study, we used stable cesium (Cs) to investigate the changes in dry Cs deposits on surfaces of aboveground parts of Chinese yam (Dioscorea polystachya) during different growth stages. Chinese yam seedlings were grown for eight different lengths of time and were then simultaneously exposed to aerosol particles containing stable Cs in an aerosol exposure chamber for 5 h. The deposition density of Cs on the aboveground parts of the seedlings decreased from 29 to 72 d after transplantation (DAT) and did not change significantly after 72 DAT. The Cs deposition density on the seedlings on different DAT correlated with the leaf area available for the deposition of aerosol Cs particles.

Preliminary investigation of the local marine reservoir effect in port JOLI harbour, NOVA scotia using archaeological M. arenaria shells

Port Joli Harbour, situated on the southwest coast of the maritime province of Nova Scotia, Canada, has the highest density of shell midden deposits in Atlantic Canada. The terrestrial radiocarbon chronology points to continuous human occupation of the harbour from 1685 cal yr BP to 250 cal yr BP. Despite the abundance of the soft-shell clams Mya arenaria at shell midden sites throughout the harbour they have not been incorporated into the chronology, nor have they been used to study the local marine reservoir effect in the harbour. We report 12 new 14C measurements on archived Mya arenaria from the same depositional contexts as previously dated charcoal and terrestrial mammal bone samples from two shell middens in Port Joli Harbour. From these shell-charcoal and shell-bone pairs, we present preliminary calculations of local marine reservoir corrections (ΔR) for the harbour. The ΔR values are highly variable and are overall more positive than the pre-bomb values reported for the Scotian Shelf. The variability of these values highlights the challenges in calculating ΔR values from archived archaeological samples but also the opportunities to include high-resolution analysis of ΔR variations in discussions on human-environment interactions in coastal settings during the late Holocene. We suggest that the chondrophore may be more favourable for calculating first order estimates of ΔR to be used in future archaeological calibrations, while high resolution analysis of the ventral margin region is useful for climate reconstructions. We recommend that more 14C measurements from M. arenaria shells be obtained from either distinct features or rapidly deposited middens in Port Joli Harbour. A suite of temporally and geographically precise ΔR values for the harbour will not only allow for the study of middens that are at risk of coastal erosion and lack charcoal for 14C dating but will also allow for the reconstruction of past climate conditions and refine our understanding of late Holocene human-environment interactions in the North Atlantic.

Donor-specific Immune Senescence as a Candidate Biomarker of Operational Tolerance Following Liver Transplantation in Adults: Results of a Prospective, Multicenter Cohort Study

Immunosuppression can be withdrawn from selected liver transplant recipients, although robust clinical predictors of tolerance remain elusive. The Immune Tolerance Network ITN056ST study (OPTIMAL) assessed clinical outcomes and mechanistic correlates of phased immunosuppression withdrawal (ISW) in non-autoimmune, non-viral adult liver transplant recipients. Enrolled subjects were ≥3 years post-transplant with minimal/absent inflammation or fibrosis on a screening liver biopsy. The primary endpoint was operational tolerance at 52 weeks following complete ISW. Of 61 subjects who initiated ISW, 34 failed during ISW and 10 restarted immunosuppression due to clinically manifest acute rejection. Of the 17 subjects remaining off immunosuppression at 1 year, 10 were ultimately deemed tolerant by biopsy. There were no cases of chronic rejection or graft loss. The majority of subjects (78.6%), including those who experienced rejection, ended the study on same or less calcineurin inhibitor than at baseline. 28.3% developed de novo DSA during ISW, which persisted in 11.3%. A minority (16.4%) of histologically and clinically stable long-term adult liver transplant recipients can successfully discontinue and remain off immunosuppression. Increased frequency of donor-specific T cell senescence, C4d deposition and higher density of immune synapses on the screening liver biopsy emerged as potential candidate biomarkers for operational tolerance. NCT02533180.

Synthesis of Ag Nanowires with High Aspect Ratio for Highly Sensitive Flexible Strain Sensor

AbstractIn recent years, the research and development of various flexible wearable devices have rapidly advanced due to the continuous introduction of flexible electronic product. These devices have found applications in health monitoring, cardiovascularcare, internal and external workload, and more.Flexible sensors, being a vital component of flexible devices, determine the functionalities and performance capabilities of the devices. Metal nanomaterials, especially silver nanowires, are widely used in flexible sensors in past research due to their great advantages in flexibility and sensitivity. In this work, Silver nanowires with aspect ratios of 600, 1000, and 1400 were synthesized by adjusting the synergy of Br‐ and Cl‐, along with other process parameters, leading to an improved production efficiency of silver nanowires.The stability of the conductive network is enhanced when the aspect ratio of silver nanowires is 1000 and 1400.The sensor demonstrated high sensitivity at high strain, along with an extended strain range.Moreover, it was observed that increasing the aspect ratio of silver nanowires led to a more stable conductive network, thus enhancing the sensor's stability with over 10000 stretching cycles. under the appropriate deposition density, silver nanowires with aspect ratio of 600 have high sensitivity to low strain, and silver nanowires with aspect ratio of 1400 have high sensitivity to high strain, up to 247.3. Introducing microstructures on the surface of PDMS resulted in an increased maximum sensitivity of the sensor with decreasing microstructure size, reaching a maximum sensitivity of 322.2.

Hail netting changes to spray droplets and patterns in grape canopies

While hail netting in vineyards provides effective protection to wine grapes (Vitis vinifera L.) from hail, pests, and bird damage, it may also affect the spray efficacy. This study tested the interaction between hail netting and location within the canopy in determining spray droplet characteristics. Two grape cultivars (Petite Sirah FPS 04 and Touriga Nacional FPS 05) grafted onto 1103P rootstock were examined to assess spray coverage, droplet size distribution, and deposition within grapevine canopies under netted and unnetted conditions. Spray droplets were measured using spray cards placed at five locations within the canopy. Significant interactions were observed primarily at the base of the canopy directly above the cordon, where grape clusters are most concentrated. Unnetted Touriga Nacional exhibited higher spray coverage compared to Petite Sirah, attributed to its looser cluster structure. Hail netting standardized all parameters across both cultivars, mitigating the influence of canopy and cluster differences. Hail netting created smaller, uniformly distributed droplets within the canopy, an essential characteristic of effective pest and disease control. Conversely, without netting, larger droplets were unevenly distributed, predominantly settling on the outer and lower canopy sections. Hail netting also maintained deposit densities within recommended ranges, supporting effective pest and disease management without compromising spray coverage. The consistent spray coverage achieved with hail netting across all canopy locations highlights its role in improving application uniformity and grapevine health, leading to evenly ripened, high-quality fruit. Contrary to the perceived risk of reducing spray efficacy, hail netting appears to enhance vineyard spraying outcomes, potentially offsetting netting costs.

A comparative analysis of an aerosol dry deposition microscale model for overhead powerlines insulators

Aerosol particles deposition on overhead power line insulators may significantly threaten electric systems, affecting dielectric properties and potentially causing surface discharges and service interruptions, leading to economic consequences. This study addresses this challenge by evaluating a dedicated microscale deposition model that integrated into an advanced air quality (AQ) modeling system. The microscale model integration into the AQ system aims to improve predictions of equivalent salt deposit density (ESDD), a key measure of insulator contamination. This enhancement is crucial for improving system resilience and reliability. The microscale model’s performance in reconstructing particulate matter (PM) deposition fluxes onto XP-70 porcelain-disk electrical insulator is assessed against measured ESDD data collected across various regions in Italy during several experimental campaigns. In order to better understand the specific phenomena impacting PM deposition, the microscale model is compared to the state-of-the-art Zhang deposition model used in CAMx. The analysis reveals that the microscale model tends to overestimate measured ESDD values and predicts higher deposition velocities than the Zhang model. These results suggest potential modelling differences between the two models, including variations in obstacle parameterizations, influence of particle aerodynamics, and dispersion modelling in the near-wall region.

Terms for describing atmospheric deposition of substances on surfaces

Relevance. The need to assess the state of the environment based on the use of terminology for quantitative chemical characteristics of the underlying surface as a result of deposition of pollutants in the composition of wet and dry fallout from the atmosphere. Aim. This study can be a source of information about the terminology used to describe the state of the underlying surface during the deposition of substances from the atmosphere, with links to scientific and technical literature. Methods. Review of some scientific and technical literature and an attempt to select terms used to quantify the ecological state of the underlying surface, mainly snow, after the arrival of substances as part of dry and wet deposition from the atmosphere, depending on the sampling method. Results and conclusions. The author has carried out an analysis of the scientific and technical literature and defined the terms applied to a quantity that has the dimension mass/area*time for assessing the ecological state of the snow cover, such as specific reserve (surface density), deposition density, atmospheric deposition density, precipitation intensity pollutant, daily deposition of chemical elements, technogenic load, dust load, pollution load (element), mass load, gas-aerosol load, technogenic pressure module, input module, atmospheric fallout module, mass of the determined component received at unit area, flux obtained on the basis of sampling during snow chemical survey. An analysis of the scientific and technical literature was also carried out and the terms applied to a value with the same dimension mass/area*time were defined to assess the ecological state of the underlying surface during the deposition of substances from the atmosphere, such as "fallout density", "atmospheric fallout density", “pollutant fallout intensity”, “aggravating substance", "precipitation", "critical load", "flow" obtained based on sample collection using plates, cuvettes, collections.

Achieving low-porosity AlSi10Mg cladding layers for the additive repair of aluminum alloy parts by directed energy deposition

Directed Energy Deposition (DED) has broad application prospects for repairing damaged aluminum alloy parts such as piston aero-engine casing. However, due to the low laser absorptivity and the complex thermal cycle process, it is challenging to obtain aluminum alloy cladding layers with high-quality morphology and low-porosity by DED method. In this work, a series of individual stages of DED process are studied during single-tracks overlapping and layers stacking. Correspondingly, the within layer scanning strategy, inter-layer stacking strategy, and process parameters are examined carefully. Using the proposed DED processing flow that combines substrate preheating with intermittent process, the deposited layers without balling and collapse are successfully achieved. Furtherly, the bi-directional scanning strategy for single-tracks overlapping within layer is proposed to compensate the thickness nonuniformity caused by heat accumulation. The inter defects identified as “lack of fusion” and “gas pores” are observed in the cladding layers with uniform surface. By analyzing the pore formation mechanism and considering the energy distribution and re-melting, the multi-layer offset stacking strategy is proposed to inhibit the porosity to 0.25 %. Combined with the optimized process parameters, the porosity is reduced up to 0.09 %, ensuring the density of the DED deposition coating. This work provides new pathway and direct guidance for fabricating high-quality AlSi10Mg cladding layers during the DED repairing of valuable aluminum alloy parts.

Optimizing Cold Spray Parameters for High Entropy Alloy Coatings Using Taguchi and Box–Behnken Design Approaches for Mechanically Alloyed Powder

AbstractThe present study focused on optimizing the cold spray (CS) process parameters for depositing Fe20Cr20Mn20Ni20Co20 (Cantor alloy) coatings using mechanically alloyed (MA) powder. A two-step design of experiments approach was employed, beginning with the initial screening of input variables using the L8 Taguchi method, followed by the refinement of process parameters through the Box–Behnken design of experiments. Key performance indicators included deposition efficiency (DE), coating thickness per pass, and microstructural parameters including porosity, cracks, and interfacial defects/delamination. The study identified process gas temperature as the primary factor influencing both DE and thickness per pass. Higher gas temperature and pressure, combined with increased scanning speed, resulted in higher DE. The DE of the MA Cantor alloy powder peaked at around 14-15%, with a deposit density greater than 99% achieved at the highest process gas temperature and pressure (1000 °C and 60 bar, respectively). The average hardness of the optimal CS coating deposited using MA powder was found to be 679 ± 17 HV0.1, which is approximately 90% greater than the average hardness reported for CS coatings deposited using atomized powder.

Coupled Discrete Phase and Eulerian Wall Film Models for Drug Deposition Efficacy Analysis in Human Respiratory Airways.

The current study explores the effectiveness of drug particle deposition into human respiratory airways to cure various pulmonary-bound ailments. It has been assumed that drug solutions are inhaled in the form of tiny droplets or mist, which after striking create a thin layer along the inner surface of airways where the virus initially resides to infect the human body. A coupled Eulerian wall film (EWF) and discrete phase model (DPM) based simulation approach is used to capture these dynamics. Here, the Lagrangian DPM technique tracks the dynamics of tiny droplets, while the liquid layer formation after striking is captured using the Eulerian thin film approximations or the EWF model. Previous studies in this field primarily employed only the DPM method, which is inadequate to predict the poststriking dynamics of drug layer deposition and their spread to neutralize the respiratory virus. The drug delivery effectiveness is characterized by three different particle sizes, 1, 5, and 10 μm at the inhalation rates of 15, 30, and 60 L per minute (LPM). It has been found that the size of the drug particles significantly influences drug delivery effectiveness. The film thickness increases monotonically with particle sizes and inhalation rates. However, this increase in averaged film thickness is prominent in the range 5 to 10 μm (≈60%) compared to 1 to 5 μm (≈10%) droplet sizes at generation level 4 (G4). The other deposition parameters, e.g., deposition fraction, deposition density, and area coverage) roughly show similar behavior with the increase in droplet sizes. Therefore, it is recommended to vary the droplet sizes between 5 and 10 μm for better deposition effectiveness. The sizes of more than 10 μm mostly stuck into the oral cavity and cannot reach the targeted generations. In contrast, less than 5 μm may reach much deeper generations than the targeted one.

Control of deposits on pipeline systems by the method of free oscillations

RELEVANCE. There are a large number of heat exchangers in operation enterprises that operate under various temperature conditions. Steam, hot water, heated products of oil refining and other industries, which may contain oxides of iron, aluminum, calcium sulfate silicates, etc., are used as a heating agent. The efficiency of the heat exchange equipment depends on the condition of the heating surfaces. Contamination of these surfaces with various deposits dramatically reduces the heat transfer coefficient, which leads to a significant increase in heat consumption. The nature of the deposits depends on the properties of the heating agent and the heated medium.THE PURPOSE. The purpose is to assess the possibility of controlling deposits on the surfaces of heat exchange equipment by the free oscillation method. The presence of deposits changes the mass of structures and, consequently, the natural frequencies of vibrations, the analysis of which can determine not only the presence and thickness of deposits, as well as their appearance.METHODS. The paper shows the results of experimental studies conducted using a hardware and software package and calculations of natural vibrations of the surfaces of heat exchange equipment in the ANSYS software package to identify their dependence on the thickness and density of deposits. A plate, a pipe, and a pressurized pipe were modeled as heat transfer surfaces.RESULTS. The results obtained experimentally and computationally coincided, and it was concluded that the free oscillation method makes it possible to determine not only the presence of deposits on heat exchange surfaces, but their thickness and appearance.CONCLUSION. The free oscillation method can detect deposits in a timely manner and monitor their condition, which in turn will, reduce overall operating costs, increase energy efficiency and extend service life.

Brown Adipose Stem Cell-Loaded Resilin Elastic Hydrogel Rebuilds Cardiac Function after Myocardial Infarction via Collagen I/III Reorganisation.

Irreversible fibrosis following myocardial infarction (MI) stiffens the infarcted myocardium, which remains challenging to restore. This study aimed to investigate whether the injectable RLP12 hydrogel, derived from recombinant resilin protein, could serve as a vehicle for stem cells to enhance the function of the infarcted myocardium. The RLP12 hydrogel was prepared and injected into the myocardium of rats with MI, and brown adipose-derived mesenchymal stem cells (BADSCs) were loaded. The survival and differentiation of BADSCs in vivo were investigated using immunofluorescence one week and four weeks after treatment, respectively. The heart function, MI area, collagen deposition, and microvessel density were further assessed four weeks after treatment through echocardiography, histology, immunohistochemistry, and immunofluorescence. The RLP12 hydrogel was prepared with a shear modulus of 10-15 kPa. Four weeks after transplantation, the RLP12 hydrogel significantly improved cardiac function by increasing microvessel density and reducing infarct area size and collagen deposition in MI rats. Furthermore, the distribution ratio of collagen III to I increased in both the centre and edge areas of the MI, indicating the improved compliance of the infarct heart. Moreover, the RLP12 hydrogel also promoted the survival and differentiation of BADSCs into cardiac troponin T- and α-smooth muscle-positive cells. The RLP12 hydrogel can be utilised as an injectable vehicle of BADSCs for treating MI and regulating collagen I and III expression profiles to improve the mechanical microenvironment of the infarct site, thereby restoring heart function. The study provides novel insights into the mechanical interactions between the hydrogel and the infarct microenvironment.

Surface-Enhanced Raman Scattering on Size-Classified Silver Nanoparticles Generated by Laser Ablation.

This study delved into the complex interplay between the nanostructural characteristics of nanoparticles and their efficacy in surface-enhanced Raman scattering (SERS) for sensitive detection of trace chemical substances. Silver nanoparticles were prepared for the SERS substrate by combining laser ablation, postannealing processes (up to 500 °C), and electrostatic mobility classification, allowing high-purity silver nanoparticles with controlling their sizes (40-100 nm) and aggregate structures. These nanoparticles were then inertially deposited on the substrates to create SERS-active surfaces, employing Rhodamine B as a probe to assess the impact of particle size, shape, and deposition density on SERS effectiveness. Our findings revealed that spherical nanoparticles, especially those approximately 50 nm in diameter, controlled to a spherical structure through gas-phase annealing at 500 °C and subsequent classification, yielded the most significant SERS enhancement. This optimal can be explained by the particle size response of the surface plasmon resonance, where the enhancement of the Raman signal for particles up to 50 nm (1/10 of the laser wavelength used in this study, 532 nm) arises from a balance between the enhancement of dipole moment and the number of "hot spot" regions (respectively proportional to the cube and inverse square of the diameters in theory, leading to a linear relationship between signal intensity and particle diameter); meanwhile, in larger size region than 50 nm, the Raman signal was decreased owing to the attribution of the phase difference between the electric field and dipole moment. Furthermore, we found that a deposition density of 2 μg resulted in nearly a single layer of particles, which is crucial for maximizing SERS hotspots and, consequently, the enhancement effect.

Ultrafast dynamics and internal processing mechanism of silica glass under double-pulse femtosecond laser irradiation

Femtosecond laser-induced plasma filaments have potential for various applications including attosecond physics, spectroscopy, and microprocessing. However, the use of plasma filaments to generate high-aspect-ratio internal modifications remains low-efficiency. Here, we experimentally demonstrated high-efficiency internal processing using plasma filaments induced by a double-pulse femtosecond laser. The processing mechanism was revealed through an investigation of the ultrafast dynamics of plasma filaments in experiments and simulations. We found that the excitation region of the first pulse (P1) exerted a temporal effect on the propagation and absorption of the second pulse (P2) due to the evolution of excited electrons, thus resulting in different processing characterizations. At a smaller inter-pulse delay (IPD), electrons and self-trapped excitons induced by P1 improved the absorption of P2 in the shallow region. Consequently, the main excitation regions of P1 and P2 were separated, resulting in a lower density of energy deposition and weak modifications. Whereas, at a larger IPD, P2 penetrated a deeper region with the relaxation of electrons and excitons induced by P1, leading to a better overlap of excitation regions between P2 and P1, thus improving the density of energy deposition and achieving efficient microprocessing. Besides, at an infinite IPD, P2 behaved like P1, but no modification was obtained owing to the complete energy diffusion of P1. Therefore, controlling the electron dynamic and energy diffusion contributes to the improvement of modification efficiency. Furthermore, the distribution of electron densities on the cross section was estimated to precisely analyze the microprocessing. These results are expected to aid in a better understanding of the interaction mechanism between dielectrics and intense ultrafast lasers and be useful for microprocessing applications.

Correlating Homogeneity and Microstructure of in Situ plated Li in “Anode-Free” Solid-State Batteries

Solid-state batteries utilizing Li metal anodes have the potential to offer increased safety and higher energy density compared to state-of-the-art Li-ion batteries. To achieve these energy density gains, the Li metal anode must be thin (<25 µm). Manufacturing of thin Li metal anodes is complicated by the reactivity of Li metal, which forms a thin passivation layer even in controlled environments. The “anode-free” cell manufacturing approach provides an alternative to these challenges. These cells are manufactured with a bare anode current collector (CC) and the Li metal anode is plated in situ at the CC/solid-state electrolyte interface during the first charging step using the Li stored in the cathode active material. While manufacturing cells with in situ formed Li anodes may offer benefits, removing all excess Li in the cell also poses many challenges. The Coulombic efficiency of these cells must be >99.99% to retain 90% capacity over 1,000 cycles [1]. Therefore, when the Li anode is formed in situ during the first charge, the temperature, pressure, and current density must be carefully tuned to optimize the reversibility of the plated Li. To achieve high reversibility of Li metal anodes, the plated Li should be dense, conformal to the current collector and solid-state electrolyte, homogeneous in thickness, and ideally have a small grain size. These objectives can be achieved by tuning the plating parameters during in situ Li deposition, including pressure, temperature, and current density. It has been previously shown that applying 5 MPa of pressure could improve the homogeneity of in situ formed Li anodes in solid-state cells [2].However, applying pressures >1 MPa is undesirable for practical applications [3]. Therefore, it is necessary to alter the in situ plated Li using other parameters, including the temperature and current density used during plating. Here, we show the effect of plating current density and temperature on the homogeneity and microstructure of in situ formed Li anodes in solid-state cells. It is demonstrated that optimized plating current protocols can improve the homogeneity of plated Li without the need for elevated temperatures. Finally, the relationship between the homogeneity of the in situ plated Li and the reversibility upon stripping is studied using unidirectional stripping experiments. These results illustrate the importance of carefully controlling the parameters for Li plating to enable high Coulombic efficiency in situ formed Li anodes in solid-state cells.

Molten Salt Electrodeposition: Review

Molten salt electrodeposition is the process of producing impressively dense deposits of refractory metals using the electrolysis of molten salts. However, predicting which electrochemical parameters and setup will best control different kinds of deposition (density, homogeneity, etc.) is an ongoing challenge, due to our limited understanding of the properties and mechanisms that drive molten salt electrodeposition. Because these advancements have been made rapidly and in different arenas, it is worth taking the time to stop and assess the progress of the field as a whole. These advancements have increasing relevance for the energy sector, the development of space materials and engineering applications. In this review, we assess four critical facets of this field: (1) how the current understanding of process variables enhances the electrodeposition of various molten salts and the quality of the resulting product; (2) how the electrochemical setup and the process parameters (e.g., cell reactions) are known to impact the electrodeposition of different metal coatings and refractory-metal coatings; (3) the benefits and drawbacks of non-aqueous molten salt electrodeposition, and (4) promising future avenues of research. The aim of this work is to enhance our understanding of the many procedures and variables that have been developed to date. The expectation is that this review will act as a stimulant, motivating scientists to delve further into the investigation of refractory-metal alloys by utilizing molten salt electrodeposition.

Spatial organisation within the earliest evidence of post-built structures in Britain.

This paper explores tool-using activities undertaken in and around the earliest known evidence of post-built structures in Britain. Microwear results associated with at least three structures identified at the Early Mesolithic site of Star Carr, North Yorkshire, are examined as a means of identifying activity zones associated with the diverse stone tools used to process a variety of materials (e.g. wood, bone, antler, plant, hide, meat, fish). With 341 lithic artefacts analysed, this research represents the first microwear study focused on the post-built structures at Star Carr. A combination of spatial and microwear data has provided different scales of interpretation: from individual tool use to patterns of activity across the three structures. Different types of tool use observed have aided interpretations of possible activity areas where objects were produced and materials were processed. Zones of activity within one of the structures suggest that the working of some materials was more spatially restricted than others; even where there are high densities of flint deposition, spatial patterns in tool-using activity were observed. From this, it is interpreted that social norms and behaviours influenced the spatial organisation of different spaces. Our results demonstrate the importance of combining microwear analysis with GIS to explore function and variability in the use of Mesolithic structures-providing new insights into their role as social spaces.

Interaction between PCB-Cu corrosion and electrochemical migration under the Coupling of electric field and thin liquid film

An in-situ monitoring and observation experimental setup was designed in the coupled environment of a thin liquid film and an electric field. The interactive development of PCB-Cu corrosion and electromigration under different bias voltages, salt concentrations, and liquid-film thicknesses was investigated, and an interactive model was proposed. The results showed that electromigration of copper was dominant at a high voltage of 3 V, whereas corrosion occurred without salt deposition at a low voltage of 1 V. The growth rate of the dendrites decreased with increasing liquid film thickness. In the presence of 1 g/m2 of NaCl, dendrite growth was absent because corrosion precipitation occurred before dendrite formation, thereby hindering the migration of copper ions. At a higher NaCl deposition density of 10 g/m2, the electromigration of copper became dominant, resulting in the formation of many short dendrites, evenly distributed on the cathode at a low voltage of 1 V. These observations are consistent with the results of the in-situ current monitoring tests.

Absolute energy-dependent scintillating screen calibration for real-time detection of laser-accelerated proton bunches.

Laser-plasma accelerators (LPAs) can deliver pico- to nanosecond long proton bunches with ≳100 nC of charge dispersed over a broad energy spectrum. Increasing the repetition rates of today's LPAs is a necessity for their practical application. This, however, creates a need for real-time proton bunch diagnostics. Scintillating screens are one detector solution commonly applied in the field of electron LPAs for spatially resolved particle and radiation detection. Yet their establishment for LPA proton detection is only slowly taking off, also due to the lack of available calibrations. In this paper, we present an absolute proton number calibration for the scintillating screen type DRZ High (Mitsubishi Chemical Corporation, Düsseldorf, Germany), one of the most sensitive screens according to calibrations for relativistic electrons and x rays. The presented absolute light yield calibration shows an uncertainty of the proton number of 10% and can seamlessly be applied at other LPA facilities. For proton irradiation of the DRZ High screen, we find an increase in light yield of >60% compared to reference calibration data for relativistic electrons. Moreover, we investigate the scintillating screen light yield dependence on proton energy since many types of scintillators (e.g., plastic, liquid, and inorganic) show a reduced light yield for increased local energy deposition densities, an effect termed ionization quenching. The ionization quenching can reduce the light yield for low-energy protons by up to ∼20%. This work provides all necessary data for absolute spectral measurements of LPA protons with DRZ High scintillating screens, e.g., when used in the commonly applied Thomson parabola spectrometers.

Process parameters for enhanced microstructure and composition of as-sprayed Yb2Si2O7 environmental barrier coatings via atmospheric plasma spray

Achieving high crystallinity levels, dense, crack-free microstructures with near-stoichiometric phase composition and controlled secondary phase formation are crucial for enhancing the performance of environmental barrier coatings (EBCs). To investigate the impact of APS process parameters on the as-sprayed crystallinity, microstructure, and phase composition of Yb2Si2O7 EBCs, various spraying conditions were explored by adjusting torch power, nozzle size, powder feedrate, stand-off distance, and adding a shroud attachment to the torch. The velocity of particles controlled the density of the EBCs by an interplay between deposition efficiency and splat flattening ratios. Increasing nozzle size from 5/16″ to 1/2″ reduced particle velocity by up to 40 %, resulting in improved deposition efficiencies, porosity levels and coating thickness. However, larger nozzles led to higher silicon evaporation and up to 8 wt% more stable Yb2SiO5 (I2/a) secondary phase was formed. Increasing the stand-off distance from 50 mm had minimal effect on microstructure, but metastable Yb2SiO5 (P21/c) was detected (up to 9 wt%) at longer stand-off distances of 100 and 150 mm. Raising the powder feedrate from 15 gr/min to 60 gr/min improved deposition efficiency (up to 9 %) and density (up to 15 %) of EBCs, yet resulted in higher silicon-depleted phase formation (up to 12 wt%). Adding a shroud to the torch nozzle exit led to severe silicon evaporation and formation of up to 42 wt% and 6 wt% of Yb2SiO5 (I2/a) and Yb2O3, respectively. Moreover, due to the shroud's funnelling effect on smaller particles as well as particle overheating, porous microstructures with up to 28 % porosity levels were formed. High levels of crystallinity (∼75–91 %) were achieved in the as-sprayed condition for all the coatings, indicating real-time crystallization during spraying in all the spraying conditions.