Deposition Monitoring Research Articles

Evaluation of reflective fiber-optic surface plasmon resonance sensor for monitoring scale deposition.

A reflective surface plasmon resonance (SPR) sensor was evaluated for real-time monitoring of scale deposition. The sensor consists of an optical fiber, only 5mm at the gold-coated tip of the sensing area. The effect of silica growth on the sensor response was evaluated using a Na2SiO3 solution. The sensitivity of the sensor to silica was 1.6 ± 0.3nm per one immersion in the solution of 1000mg/L (as SiO2) at 85°Cand subsequnt air drying, as indicated by theSPR peak shift. The amount of silica deposited on the gold surface was measured by the quartz crystal microbalancemethod, and the SPR sensitivity of 0.089nm/ng to silica mass was obtained. The detection limit (3σ) of the SPR sensor was 17ng, correspondingto a thickness of 2.5nm for amorphous silica. The SPR sensor wastested in geothermal brine sampled at the Sumikawa Geothermal Power Plant, where a clear SPR shift was observed, suggesting the effectiveness of the SPR sensor for scale monitoring.

A novel tauopathy model mimicking molecular and spatial aspects of human tau pathology.

Creating a mouse model that recapitulates human tau pathology is essential for developing strategies to intervene in tau-induced neurodegeneration. However, mimicking the pathological features seen in human pathology often involves a trade-off with artificial effects such as unexpected gene insertion and neurotoxicity from the expression system. To overcome these issues, we developed the rTKhomo mouse model by combining a transgenic CaMKII-tTA system with a P301L mutated 1N4R human tau knock-in at the Rosa26 locus with a C57BL/6J background. This model closely mimics human tau pathology, particularly in the hippocampal CA1 region, showing age-dependent tau accumulation, neuronal loss and neuroinflammation. Notably, whole-brain 3D staining and light-sheet microscopy revealed a spatial gradient of tau deposition from the entorhinal cortex to the hippocampus, similar to the spatial distribution of Braak neurofibrillary tangle staging. Furthermore, [18F]PM-PBB3 positron emission tomography imaging enabled the quantification and live monitoring of tau deposition. The rTKhomo mouse model shows potential as a promising next-generation preclinical tool for exploring the mechanisms of tauopathy and for developing interventions targeting the spatial progression of tau pathology.

Development of an integrated online deposition and corrosion monitoring system in a full-scale solid waste CFB boiler

Solid waste incineration is a clean and sustainable approach for solid waste management. However, ash deposition and corrosion remain a critical issue due to fuel’s inherent enrichment of alkali chlorine. This study develops an integrated online deposition and corrosion monitoring system to enhance the operational safety and efficiency of solid waste incineration boilers. This system combines linear polarization resistance (LPR) for corrosion rate estimation with heat flux measurements for ash deposition analysis. It can offer a novel approach for real-time monitoring of heat exchangers’ safety during solid waste combustion. It was deployed in a full-scale circulating fluidized bed (CFB) boiler that purely combust solid wastes. Key findings demonstrate the system’s capability to deliver continuous, real-time data, crucial for the dynamic control of combustion processes and the maintenance of heat transfer surfaces. Its robust diagnostic capabilities were evident across various scenarios. Specially, initial corrosion rates sharply increase with deposition rates due to the enrichment of alkali chlorine on inner deposit layer, in which chlorine serves as a catalyst, facilitating the rapid penetration and aggravation of corrosion by other agents. As deposit further buildup, the corrosion rate steadily decreases along with surface temperature, highlighting a dynamic interaction. Moreover, measured corrosion rates can quickly response to temperature variations. Such multi-process online monitoring system provide more possibilities to investigate the inherent interaction between deposition and corrosion. Therefore, this work offers insights that could significantly influence operational strategies, maintenance protocols, and the overall reliability of waste-to-energy technologies.

Navigating environmental cooperation on air pollution amid political competition in East Asia

Abstract East Asian countries have recently upgraded their regional cooperation for clean air through the Acid Deposition Monitoring Network in East Asia, with elaborate arrangements for monitoring and capacity-building assistance for multiple pollutants. This represents a departure from the earlier informal regimes with vague arrangements on acid deposition. However, despite this notable shift, this formalization in the regional governance for clean air remains largely unexplored in the existing literature. This study fills this gap by analysing the dynamics of formalization through aid from theories of regime complexity and legalization. It focuses on the decade from 2012 to 2021, employing documentary analysis and interviews. The results reveal that governments actively pursue their state interests by adjusting institutional arrangements through regime competition and selection that drive formalization. Sharing cognition of the hazardousness of multiple pollutants achieved through interactions between regional and global institutions serves as a catalyst for reaching an agreement on the arrangements.

Demonstrating a Quartz Crystal Microbalance with Dissipation (QCMD) to Enhance the Monitoring and Mechanistic Understanding of Iron Carbonate Crystalline Films.

This paper reports the real time monitoring of siderite deposition, on both Au- and Fe-coated surfaces, using the changes in frequency and dissipation of quartz crystal microbalance with dissipation (QCMD). In an iron chloride solution saturated with carbon dioxide, buffered with sodium bicarbonate to pH 6.8, roughly spherical particles of siderite formed within 15 min, which subsequently deposited on the QCMD crystal surface. Imaging of the surface showed a layer formed from particles ca. < 0.5 μm in diameter. Larger particles are clearly deposited on top of the lower layer; these larger particles are >1 μm in diameter. Monitoring of the frequency clearly differentiates the formation of the lower layer from the larger crystals deposited on top at later times. The elastic moduli calculated from QCMD data showed a progressive dissipation increase; the modeling of the solid-liquid interface using a flat approximation resulted in a poor estimation of elastic and storage moduli. Rather, the impedance modeled as a viscoelastic layer in contact with a semi-infinite liquid, where a random bumpy surface with a Gaussian correlator is used, is much more accurate in determining the elastic and storage moduli as losses from the uneven interface are considered. A further step considers that the film is in fact a composite consisting of hard spherical particles of siderite with water in the vacant spaces. This is treated by considering the individual contributions of the phases to the losses measured, thereby further improving the accuracy of the description of the film and the QCMD data. Collectively, this work presents a new framework for the use of QCMD, paired with traditional approaches, to enhance the understanding of crystal deposition and film formation as well as quantify the often evolving mechanical properties.

Atmospheric wet and dry phosphorus deposition in Lake Erhai, China

Lake Erhai is a potentially phosphorus (P)-limited lake and its water quality may have been affected by atmospheric P deposition. However, there have been few studies on atmospheric P deposition in this lake. In this study, we established five wet deposition monitoring sites and two dry deposition monitoring sites around Lake Erhai to quantify the wet and dry deposition of total phosphorus (TP), including dissolved inorganic phosphorus (DIP), dissolved organic phosphorus (DOP) and particulate phosphorus (PP) from July 2022 to June 2023. Wet deposition fluxes of P species were collected by automatic rainfall collection instrument, and dry deposition fluxes were estimated using airborne concentration measurements and inferential models. The results reveal that among the different P components, DOP had the highest contribution (50%) to wet TP deposition (average all sites 12.7 ± 0.7 mg P m2/yr), followed by PP (40%) and DIP (10%). Similarly, DOP (51%) was the major contributor to dry TP deposition (average two sites 2.4 ± 0.9 mg P m2/yr), followed by DIP (35%) and PP (14%). Wet deposition dominated the annual total TP deposition (wet plus dry), accounting for approximately 83%. The key seasons for dry deposition were spring and autumn, which accounted for 64% of the annual total dry TP deposition. In comparison, wet deposition was significantly higher in the summer, accounting for 73% of the annual total wet TP deposition. The results of the potential source contribution function and concentration-weighted trajectories analysis indicate that local source emission and long-range transport from surrounding cities jointly exerted a substantial influence on aerosol P concentrations, particularly in the eastern and northwestern regions of the lake. These findings provide a comprehensive understanding of the different P components in atmospheric deposition, which is beneficial for developing effective strategies to manage the P cycle in Lake Erhai.

In-situ monitoring of additive friction stir deposition of AA6061: Effect of rotation speed on the microstructure and mechanical properties

The AA6061 alloy depositions fabricated under three rotation speeds (Ω, 450, 500 and 550 rpm) are obtained by the additive friction stir deposition (AFSD) technique in this study. The real-time temperature, force and torque during the AFSD process were monitored by a self-developed process-aware kit, helping to thoroughly investigate the influence of Ω on the microstructure and mechanical properties of the depositions. Combined with the results of the electron back scattered diffraction (EBSD) analysis on a large area (4 × 4 mm2), it is found that the grain size increases with the increase of Ω due to high heat generation. The proportion of deformation texture components reduces because of the lower strain distribution as well as the slight deformation behavior. A higher average micro-hardness is found on the 550 rpm-deposition because of the dislocation strengthening effect. Furthermore, the values of yield strength (87.8 MPa) and ultimate tensile strength (147.2 MPa) of the depositions are the highest when the Ω is the lowest (450 rpm), owing to the lowest thermal cycle. All the results are intended to provide useful guidance and a theoretical basis for producing high-performance Al-based alloys through AFSD.

Monitoring and estimation of mining and geometric indicators of the deposit

The article presents the results of mining and geometric modeling of indicators of mineral deposits. In order to estimate and monitor them, a wide range of geoinformation systems-based methods and techniques of geometrization is applied. The sequence and stages of mining and geometric estimation of deposits are described considering specific mining and geological conditions. The built models are used at Ukraine’s mining enterprises that develop solid minerals. Much attention is paid to processing initial mining and geological data, providing the basis for mining and geometric modeling. Geostatistical methods give high results when processing and assessing reliability of the input modeling data and processing and presenting modeling results. Different types of deposits require different approaches to geometrization. Deposits with high variability of indicators require accounting, data grouping and zoning. For this purpose, a heuristic algorithm is developed, which is an efficient independent method of modeling and enables considering the high level of heterogeneity of the spatial distribution of mining and geological indicators of the deposit. The results of the modeling can be used for deposit estimation and monitoring, reserves calculation, and mining operations planning.

In situ process monitoring of multi-layer deposition in wire arc additive manufacturing (WAAM) process with acoustic data analysis and machine learning

In situ process monitoring of multi-layer deposition in wire arc additive manufacturing (WAAM) process with acoustic data analysis and machine learning

Temporal-spatial characteristics and sources of heavy metals in bulk deposition across China

With the rapid development of industries, agriculture, and urbanization (including transportation and population growth), there has been a significant alteration in the emission and atmospheric deposition of heavy metal pollutants. This has consequently given rise to a range of ecological and environmental health issues. In this study, we conducted a comprehensive two-year investigation on the temporal and spatial distribution characteristics of heavy metals in atmospheric deposition across China based on the Nationwide Nitrogen Deposition Monitoring Network (NNDMN). The atmospheric bulk deposition of Lead (Pb), Arsenic (As), Nickel (Ni), Selenium (Se), Chromium (Cr) and Cadmium (Cd) were 6.32 ± 1.59, 4.49 ± 0.57, 1.31 ± 0.21, 1.05 ± 0.16, 0.60 ± 0.06 and 0.21 ± 0.03 mg m−2 yr−1, respectively, with a large variation among the different regions of China. The order for atmospheric deposition flux was Southwest China > Southeast China > North China > Northeast China > Qinghai-Tibet Plateau and rural area > urban area > background area. The concentrations of heavy metals in bulk deposition exhibit seasonal variation with higher levels observed during winter compared to summer and spring, which are closely associated with anthropogenic activities. The Positive Matrix Factorization (PMF) results indicated that combustion, industrial emissions and traffic are the primary contributors to atmospheric deposition of heavy metals. The single factor pollution index (Pi) of heavy metals is consistently below 1, and the composite pollution index (Ni) is 0.16 across China, indicating that atmospheric heavy metal deposition is at a pollution-free level. The comprehensive potential ecological risk index of heavy metals is 11.8, with Cd exhibiting the highest single factor potential ecological risk index at 7.09, suggesting that more attention should be paid to Cd deposition in China. The present study reveals the spatial-temporal distribution pattern of atmospheric heavy metals deposition in China, identifying regional source characteristics and providing a theoretical foundation and strategies for reducing emissions of atmospheric pollutants.

Carbon wet deposition flux and river carbon output in a forest watershed in permafrost region of the Da Xing'an Mountains.

Carbon wet deposition and river carbon output in river basins are important components of global carbon cycle. The assessment of both properties is of great significance for regional carbon budget. However, research on these topics in high-latitude permafrost regions in China is still lacking. We conducted dynamic monitoring of carbon wet deposition and carbon output in the river from May 28th to October 30th, 2022, in Laoyeling watershed, a typical forested watershed in the Da Xing'an Mountains permafrost region. We analyzed the variations of carbon component concentrations and fluxes in precipitation and river water, and estimated the contribution of carbon wet deposition to carbon output in the watershed. The results showed that wet deposition fluxes of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and total dissolved carbon (TDC) in the Laoyeling watershed were 1354.86, 684.59, and 2039.45 kg·km-2, respectively. The fluxes of DOC, DIC, TDC, particulate organic carbon (POC), particulate inorganic carbon (PIC), and total carbon (TC) in the river were 601.75, 1977.30, 2579.05, 125.13, 21.99, and 2726.17 kg·km-2, respectively. The contribution of TDC wet deposition to the river TDC output was 9941.89 kg, accounting for 17.6% of total output. The DIC concentration in the river showed significant seasonal differences, with increased runoff resulting from precipitation leading to a decrease in DIC concentration in the river and showing a clear dilution effect, while the concentrations of DOC, POC, and PIC increased, mainly due to erosion effect. In conclusion, carbon wet deposition flux in the Laoyeling watershed was mainly determined by precipitation, and its contribution to river carbon output was relatively small compared to other factor. Runoff was the dominant factor affecting river carbon output. The results would provide important insights into carbon cycling and carbon budget balance in permafrost regions under climate change.

In-situ monitoring of additive friction stir deposition of AA6061: Effect of layer thickness on the microstructure and mechanical properties

Depositions of AA6061 aluminum alloy with different thicknesses (0.5, 1.0 and 1.5 mm) and homogeneous microstructure were successfully obtained through additive friction stir deposition (AFSD) technique. A self-developed in-situ process monitoring kit has been utilized to in-situ monitor the real-time temperature, force and torque during the AFSD process. Effect of thickness on the microstructure and mechanical properties are investigated based on the monitored parameters. With the electron back scattered diffraction (EBSD) analysis on a large area (4 × 4 mm2), the synergism of dynamic recrystallization (DRX) and shear deformation is found to affect the microstructure. DRX is the main reason for the grains refinement which are remarkably reduced to 7 μm as the thickness increases. Whereas, the shear deformation exhibits a stronger effect on the texture. The texture intensity reduces and then increases as the thickness increases from 0.5 to 1.5 mm. Values of micro-hardness (46.8 HV0.5), yield strength (106.0 MPa) and ultimate tensile strength (171.2 MPa) of the deposition are the highest when the thickness is the largest (1.5 mm) attributed to the lowest thermal cycle and evolution of DRX. All the findings provide useful guidance for the visualization and understanding of AFSD process.

Spatial patterns and temporal trends of trace elements in mosses from 1990 to 2020 in Germany

BackgroundThe accumulation of trace elements in mosses is used as an indirect measure of atmospheric deposition and an important complement to the techniques used to monitor the Geneva Air Pollution Convention. The aim of this paper is to quantify and map temporal and spatial trends of metal enrichment in mosses collected in Germany in 1990, 1995, 2000, 2005, 2015 and 2020. Collection and chemical analysis of the moss samples were carried out according to international guidelines.ResultsThe analysis shows that since 1990, the median concentrations of As, Cd, Cu, Ni, Pb and Sb in the mosses have been decreasing significantly, with the with the highest decline of Pb (− 86%). This trend reversed in 2000 and 2005 and between 2015 and 2020 by increases in the concentrations of some trace elements. In the 2000 Moss Survey, higher concentrations were measured for Cd, Cu, Ni and Sb than in 2015, ranging from + 26% (Cu) to + 165% (Ni). For As and Pb, no significant changes can be observed in 2020 compared to 2015. The increase in metal concentrations in the mosses over the last five years does not correspond to the corresponding trends in reported metal emissions in Germany (2015–2020). In contrast, the long-term trends of the As, Cd, Cu, Ni and Pb concentrations measured in the mosses showed good overall correspondence with the emission trends in Germany (1990–2020). The long-term trends of the moss data are mostly weaker than those of the emission data. The spatial patterns of the temporal trends were mapped and discussed for As, Cd, Cu, Ni, Pb and Sb.ConclusionsThe study shows that for valid monitoring of atmospheric deposition, it is not enough to consider only emission data or the modelled deposition derived from these data. In this respect, the study provides one of many necessary contributions to the discussion on the extent to which analytes of current monitoring programmes are still relevant and up-to-date and whether there are new substances that are also relevant or even more relevant than existing analytes and to what extent this should be taken into account in designing future environmental monitoring.

Implementation of the ISORROPIA-lite aerosol thermodynamics model into the EMAC chemistry climate model (based on MESSy v2.55): implications for aerosol composition and acidity

Abstract. This study explores the differences in performance and results by various versions of the ISORROPIA thermodynamic module implemented within the ECHAM/MESSy Atmospheric Chemistry (EMAC) model. Three different versions of the module were used, ISORROPIA II v1, ISORROPIA II v2.3, and ISORROPIA-lite. First, ISORROPIA II v2.3 replaced ISORROPIA II v1 in EMAC to improve pH predictions close to neutral conditions. The newly developed ISORROPIA-lite has been added to EMAC alongside ISORROPIA II v2.3. ISORROPIA-lite is more computationally efficient and assumes that atmospheric aerosols exist always as supersaturated aqueous (metastable) solutions, while ISORROPIA II includes the option to allow for the formation of solid salts at low RH conditions (stable state). The predictions of EMAC by employing all three aerosol thermodynamic models were compared to each other and evaluated against surface measurements from three regional observational networks in the polluted Northern Hemisphere (Interagency Monitoring of Protected Visual Environments (IMPROVE), European Monitoring and Evaluation Programme (EMEP), and Acid Deposition Monitoring Network of East Asia (EANET)). The differences between ISORROPIA II v2.3 and ISORROPIA-lite were minimal in all comparisons with the normalized mean absolute difference for the concentrations of all major aerosol components being less than 11 % even when different phase state assumptions were used. The most notable differences were lower aerosol concentrations predicted by ISORROPIA-lite in regions with relative humidity in the range of 20 % to 60 % compared to the predictions of ISORROPIA II v2.3 in stable mode. The comparison against observations yielded satisfactory agreement especially over the USA and Europe but higher deviations over East Asia, where the overprediction of EMAC for nitrate was as high as 4 µg m−3 (∼20 %). The mean annual aerosol pH predicted by ISORROPIA-lite was on average less than a unit lower than ISORROPIA II v2.3 in stable mode, mainly for coarse-mode aerosols over the Middle East. The use of ISORROPIA-lite accelerated EMAC by nearly 5 % compared to the use of ISORROPIA II v2.3 even if the aerosol thermodynamic calculations consume a relatively small fraction of the EMAC computational time. ISORROPIA-lite can therefore be a reliable and computationally efficient alternative to the previous thermodynamic module in EMAC.

Monitoring of rainwater quality in Kandy and Peradeniya, Sri Lanka.

The composition of atmospheric deposition is a measure of air quality, an important aspect of the health of the ecosystem. Consequently, continuous monitoring of atmospheric deposition is crucial to obtain remedial measures to avoid undesirable aspects that would affect living things. In this context, the objective of this study was to determine the rainwater quality at selected locations in Kandy and Peradeniya area of Sri Lanka, namely, Kandy, Polgolla, and University of Peradeniya (UOP), and to identify possible correlations between quality parameters through statistical means. Forty (40) rainwater samples from the UOP site and seven (07) samples each from the Kandy and Polgolla sites were collected from 18 May 2020 to 28 April 2021. The volume-weighted average (VWA) pH values of UOP, Kandy, and Polgolla sites were determined to be 7.44, 7.19, and 7.19, respectively, and moreover, acid rain (pH < 5.6) occurrences were not detected during the sampling period. The VWA values of rainfall, conductivity, salinity, TDS, and hardness at the UOP site were 40.12 mm, 51.93 μS cm-1, 0.0300 ppt, 26.59 mg L-1, and 13.55 mg L-1, respectively. The corresponding values of the Kandy site were 16.52 mm, 64.04 μS cm-1, 0.0361 ppt, 30.80 mg L-1, and 19.49 mg L-1, respectively; and those of the Polgolla site were 33.10 mm, 53.90 μS cm-1, 0.0310 ppt, 25.76 mg L-1, and 19.31 mg L-1, respectively. The VWA values of conductivity, salinity, and TDS were the highest at the Kandy site. Further, the VWA values of hardness at Kandy and Polgollasites were approximately equal, probably due to the spring of Ca2+ and Mg2+ particulates from the dolomite quarry located in Digana area. The most prominent anion was identified as Cl- in bulk deposition at all three sites, while NO3- showed the lowest concentration of all sites. Moreover, very strong significant positive correlations were identified between conductivity-TDS, conductivity-salinity, conductivity-hardness, TDS-hardness, TDS-salinity, salinity-hardness, SO42--Cl-, and NO3--Cl- according to the relevant Pearson correlation coefficients. It is thus concluded that the pollutants come from the same sources, either natural or anthropogenic.

Risk assessment and source apportionment of available atmospheric heavy metal in a typical sandy area reservoir in Inner Mongolia, China

This study evaluated dry and wet deposition of atmospheric heavy metals (HMs) in a sandy area of Inner Mongolia, China, with the Dahekou Reservoir, Xilin Gol League, adopted as the study area. Monthly monitoring of atmospheric HM dry and wet deposition was conducted over one year (2021 to 2022) at 12 monitoring points, producing 144 dry and wet deposition samples, respectively. The sample contents of eight HMs (Cr, Ni, Pb, Cu, Zn, Mn, As, and Cd) were determined to estimate the fluxes of available forms of heavy metal (AHM) in dry and wet deposition. The potential ecological index (Eri), risk assessment coding (RAC), and ratio of secondary phase to primary phase (RSP) were used to evaluate the impact of atmospheric HM dry deposition on ecological security. Correlation analysis, principal component analysis, and the absolute principal component scores-multiple linear regression (APCS-MLR) receptor model were used to quantitatively analyze the sources of AHMs in atmospheric dry and wet deposition. The results showed that the study area experienced annual dry and wet deposition fluxes of AHMs of 1712.59 kg and 534.97 kg, respectively. Atmospheric heavy metal dry deposition over the entire year presented a strong ecological risk, with Cd contributing most to this risk. Risk assessment of HM speciation showed that the greatest risks of migration and transformation were for Cd and Pb. The APCS-MLR receptor model identified five and three sources of dry and wet deposition, respectively, in order of proportion of total contribution of: natural wind and sand > road traffic and coal combustion > mineral mining > other human activities > industrial soot.

Development and Comparison of a Novel Mid‐Region Directed p‐Tau 181 Assay with Tau Positron Emission Tomography in Alzheimer’s Disease

AbstractBackgroundSeveral blood‐based phosphorylated tau (p‐tau) assays that focus on the N‐terminus have been developed and established as non‐invasive biomarkers for detecting Alzheimer’s disease (AD) pathologies from their early stages. However, the p‐tau measured by these assays may not necessarily reflect the accumulation of tau lesions in the brain due to correlation with Aβ burden. Therefore, there remains a significant unmet need to develop blood‐based tau biomarkers that are interchangeable with tau deposits in the brain.MethodsWe have devised a novel Simoa assay that can detect N‐ and C‐terminally truncated fragment of p‐tau181 in plasma (QST assay), utilizing an antibody against the mid‐region of tau protein for capture, and an antibody AT270 for detection. The plasma p‐tau181 was measured with both the QST assay and a conventional p‐tau181 Simoa assay (Quanterix) in 164 subjects, including 40 cognitively normal (CN) individuals, 48 with AD continuum, 50 with progressive supranuclear palsy, and 26 with other frontotemporal lobar degeneration, who underwent Aβ (11C‐PiB) and tau (18F‐PM‐PBB3, Florzorotau) positron emission tomography (PET) scans. Subsequently, we conducted a head‐to‐head comparison of p‐tau181 assays in correlation with the imaging biomarker and cognitive dysfunction.ResultsQST p‐tau assay demonstrated inferior performance compared to the Quanterix assay in the qualification of Aβ PET (QST assay: AUC = 0.771, Quanterix assay: AUC = 0.867). Neither assay showed a significant correlation with Aβ PET accumulation in the AD group. Meanwhile, the QST assay exhibited excellent correlations with tau PET accumulation in regions indicative of AD including temporal cortex and neocortex (p&lt;0.0005), whereas the Quanterix assay demonstrated non‐linear correlations with tracer binding. In trajectories from CN to AD continuum, the QST assay exhibited a linear association, as well as tau PET accumulation, while the Quanterix assay exhibited a sigmoidal curve association.ConclusionsWe have developed a new p‐tau181 assay directly correlated with tau PET accumulation. This quantitative system serves as a promising surrogate marker for tau lesions in the AD brain, which facilitate screening and monitoring of tau deposits in various settings, including developing disease‐modifying therapeutics.

Variability of sulfur and oxygen isotope values within wet precipitation and its correlation with diminished anthropogenic sulfur dioxide (SO2) emission

Atmospheric sulfate (SO42−) aerosols have the capacity to scatter solar radiation, thus exerting a cooling effect on the climate. It is widely acknowledged that SO42− deposition significantly contributes to ecosystem effect in aquatic and terrestrial environments worldwide. Over the course of several decades, considerable efforts have been undertaken to mitigate anthropogenic sulfur dioxide (SO2) emissions in China, leading to remarkably low SO2 concentrations. Nevertheless, the implications of reduced anthropogenic SO2 emission on atmospheric sulfate transformation and compositions of isotope values (δ34S-SO42–, δ18O-SO42–) remain inadequately understood. To address this knowledge gap, we conducted multiple rainfall sampling instances between 2010 and 2022 (n = 191), encompassing the period of transitioning anthropogenic SO2 emission from high to low levels. Remarkably, we observed a significant reduction in the volume-weighted mean value (VWMV) of SO42− concentrations, declining from 20.86 mg L−1 in 2010 to 2.41 mg L−1 in 2022, and the VWMV of SO42−/NO3− molar ratios also decreased from 12.90 in 2010 to 0.55 in 2022, reflecting the synchronously decreasing annual SO2 emissions and annual SO2 concentrations from 2010 to 2022. In contrast to the declining trends in VWMV of SO42− concentrations, the VWMV of δ34S-SO42– values exhibited a different pattern from 6.6‰ in 2010 to −0.1‰ in 2017 and slightly increased to 2.5‰ in 2022. Furthermore, the VWMV of δ18O-SO42– values demonstrated an increase from 8.8‰ in 2010 to 14.5‰ in 2018, but subsequently decreased to 5.4‰ in 2022. We attributed the sharply dropping VWMV of δ34S-SO42– values to the reduction in the input of primary sulfate with enriched δ34S-SO42– values. The strict desulfurization reduced SO2 emissions, leading to oxidation of these trace SO2 with negative δ34S values, resulting in low sulfate concentrations and negative δ34S-SO42– values. In addition, the monthly average δ18O-SO42– values exhibited a positive correlation with monthly mean δ18O-H2O values (p < 0.05), strongly indicating the water incorporation during SO2 heterogeneous oxidation. More importantly, during spring rainfall, positive δ18O-SO42– values but relatively negative δ34S-SO42– values were influenced by SO2 heterogeneous oxidation facilitated by air oxygen catalyzed under metal ions in dry weather condition, attributed to the low relative humidity (RH) coupled with high deuterium excess (dexcess) values. Conversely, in summer, negative δ18O-SO42– values but relatively positive δ34S-SO42– values resulted from the SO2 heterogeneous oxidation with H2O2 due to high RH and low dexcess values. Moreover, the VWMV of δ18O-H2O exhibited variations from −3.7‰ in 2019 to −9.7‰ in 2021, and displayed a positive correlation with annual temperature (p < 0.01) and a negative correlation with annual precipitation (p < 0.05), making it a valuable indicator of climate change alongside δ18O-SO42– values. Our findings underscore the importance of continued monitoring of atmospheric wet depositions in response to changes in anthropogenic SO2 emission activities. Furthermore, they highlight the substantial impact of variations in δ34S values of SO2 and primary sulfate on rainwater sulfate concentrations and isotope values.

Dataset of in-situ coaxial monitoring and print’s cross-section images by Direct Energy Deposition fabrication

Coaxial monitoring of the Direct Energy Deposition (DED) machines enables a real-time material deposition study. Coaxial-images contain substantial melt-pool information and incorporate situational information including the sparks’ intensity, numbers, etc. Recent studies have shown that melt-pool observations correlate directly with machine parameters and artifact properties. Therefore, the melt-pool information not only can assist in measuring the machine’s working condition and determining machine operation parameters’ reliability but also facilitates the deposition characteristics studies like print’s regime and dimensions. This information is gathered during the fabrication and can be expanded to perform various process studies and fault registration. This paper utilizes the Optomec DED machine to fabricate single-track prints with multiple process parameters, while a coaxial camera records the deposition. Each deposited track is then cut perpendicular to the print’s direction to facilitate process parameters correlation study with actual geometrical deposition measured using a microscope. The coaxial images taken during fabrication, along with their process parameters, cross-cut measurements, and a developed image-processing toolbox, are presented alongside this paper to empower future research directions.

Experimental Study on Interaction between Slurry and Soil on Excavation Face of Shield in Sand Stratum

In sandy soil, the timely and effective formation of a filter cake is crucial for maintaining the stability of the excavated face during slurry shield tunnelling. Obtaining real-time information on slurry infiltration and particle migration is challenging, which greatly impacts the formation of the filter cake. Real-time monitoring of slurry infiltration and particle deposition is achieved through the use of electrical resistivity and pore water pressure measurements of the soil. It has been discovered that the primary pathway for slurry infiltration is inevitable in sandy soil, and it is crucial to take note of the persistent slurry leakage resulting from this situation in the shield excavation face. The distribution of slurry particle deposition is highly non-uniform in the penetration direction, with the maximum particle deposition occurring at the slurry-soil interface. However, this deposition is susceptible to disturbance from shield cutting tools, which can compromise the safety of the excavation face. Even if the particle size of the slurry is smaller than the pore size of the sand stratum, the slurry with higher viscosity can still form an internal filter cake. Furthermore, the research indicates that slurry infiltration can induce regular changes in soil electrical resistivity.