Dense Aggregates Research Articles

20-year Performance of SPS-2 Sections in North Dakota and Wisconsin

The Long Term Pavement Performance (LTPP) Specific Pavement Studies (SPS-2) experiment was designed to study the structural factors, such as drainage, base type, concrete strength, slab thickness, and lane width for rigid pavements. The SPS-2 experiment sections in North Dakota and Wisconsin, constructed in 1994, are jointed, dowelled plain concrete pavement. SPS-2 sections in North Dakota and Wisconsin are considered as sister sections since they were built in the same year. The experiment consisted of six and eight supplemental sections in North Dakota and Wisconsin, respectively in addition to 12 standard SPS-2 sections. These sections have been monitored by the LTPP program since construction. Performance monitoring included measurements for ride quality (International Roughness Index, IRI), faulting, cracking, and load transfer efficiency based on surface deflections. The main objective of the study is to compare 20- year performance of SPS-2 sections in North Dakota and Wisconsin. Performance parameters analyzed in this study included IRI, faulting, load transfer efficiency, cracking, spalling, scaling, and pumping. The results show that the sections have performed well to date. Most of the sections are smooth, crack free, and have negligible faulting. Thinner sections (203 mm) over dense graded aggregate base and lean concrete base are the smoothest in North Dakota and Wisconsin, respectively. Thinner sections (203 mm) over lean concrete base and permeable asphalt treated base are the roughest in North Dakota and Wisconsin, respectively. The effect of base type on the smoothness of thicker sections is not clear. Thinner sections (203 mm) are smoother than thicker sections for the same base type in general except a Wisconsin section with thicker slab (279 mm) and a higher flexural strength (6.2 MPa) over permeable asphalt treated base.

A comparative study on microstructures and slag resistance of Al2O3–MgO castables with dense and lightweight aggregates

A comparative study on microstructures and slag resistance of Al₂O₃–MgO castables with dense and lightweight aggregates

15-Year Performance of SPS-2 Project in Kansas

The Long Term Pavement Performance (LTPP) SPS-2 experiment was designed to study the structural factors, such as drainage, base type, concrete strength, thickness, and lane width for rigid pavements. The SPS-2 experiment section in Kansas, constructed in 1992, is a jointed, dowelled plain concrete pavement. The experiment consisted of twelve standard SPS-2 sections and one Kansas Department of Transportation (KDOT) supplemental/control section. These sections have been monitored by the LTPP program since construction. Performance monitoring included measurements for ride quality (International Roughness Index, IRI), faulting, cracking, and surface deflections. Performance parameters analyzed in this study included IRI, faulting, cracking (combined longitudinal and transverse crack lengths), and joint load transfer efficiency (LTE). The results show that the project has performed very well to date. Most sections are smooth, crack free, and have negligible faulting. The load transfer efficiency of the sections has been good too. The drainable sections with permeable asphalt treated base have performed the best. These sections were built smoother and remained so after 15 years of service. The section with low PCC slab thickness (203-mm) and low concrete design strength (3.8-MPa) on dense graded aggregate base has performed the worst. The combination of high slab thickness and high concrete strength tends to mask the effect of base on pavement performance. The KDOT supplemental/control section with thick slab (305-mm) over dense graded, Portland cementtreated base has also performed very well. Statistical analysis of IRI and LTE data also supports these conclusions.

Liquid-liquid phase separation driven by charge heterogeneity

Despite the intrinsic charge heterogeneity of proteins plays a crucial role in the liquid-liquid phase separation (LLPS) of a broad variety of protein systems, our understanding of the effects of their electrostatic anisotropy is still in its early stages. We approach this issue by means of a coarse-grained model based on a robust mean-field description that extends the DLVO theory to non-uniformly charged particles. We numerically investigate the effect of surface charge patchiness and net particle charge on varying these features independently and with the use of a few parameters only. The effect of charge anisotropy on the LLPS critical point is rationalized via a thermodynamic-independent parameter based on orientationally averaged pair properties, that estimates the particle connectivity and controls the propensity of the liquid phase to condensate. We show that, even though directional attraction alone is able to lower the particle bonding valence—thus shifting the critical point towards lower temperatures and densities—directional repulsion significantly and systematically diminishes the particle functionality, thus further reducing the critical parameters. This electrostatically-driven shift can be understood in terms of the additional morphological constraints introduced by the directional repulsion, that hinder the condensation of dense aggregates.

Mesophotic and Bathyal Echinoderms of the Italian Seas

Echinoderms are among the most charismatic megabenthic taxa in mesophotic and deep waters. However, they generally have a scattered distribution and are difficult to collect, especially on hardgrounds, so defining their abundance, distribution and ecological preferences is challenging. The largest available Italian remotely operated vehicle dataset, including 624 dives carried out between 2006 and 2022 in coastal and offshore areas in the depth range of 40–1825 m, was used to assess echinoderm diversity and large-scale geographic and bathymetric distributions. Thirty-nine taxa were identified, including three rarely reported from the Mediterranean basin. The maximum diversity and occurrence of the deep-sea echinoderm fauna were reported from the northern areas, and generally, they decreased with depth and distance from the coast. Species, mostly of Atlantic origin, were mainly distributed according to their thermic preferences. The recorded species occurred in a large variety of habitats, including some in which, differently from what was reported in the literature, they formed dense aggregations. The high densities of individuals were hypothesised to be related, in some cases, to reproductive, feeding or stress situations. Environmental predictors were considered in order to both investigate patterns in community composition and the response of the studied community to them. This work enhances the knowledge of deep-sea Mediterranean echinoderms, fundamental to implementing more effective monitoring and conservation strategies for the habitats in which they thrive.

Reverse drill holes: remarkable mistakes made by gastropod predators attacking Neogene bivalve prey

Abstract Predation is a behavior that is commonly unsuccessful, but the cause of failure is often difficult to determine in the fossil record. Here, we report on gastropod drill holes in two Plio- and Miocene bivalve specimens from the Netherlands created from the inner side of the bivalve prey's shell, which we call reverse drill holes. These holes are unequivocally caused by failure of the gastropod drilling predators to make effective use of their chemoreception and mechanoreception sensory adaptations. We hypothesize that the diffuse nature of chemical cues emanating from dense aggregations of living prey could have confused foraging predators and stimulated them to initiate the drilling process on empty valves. Poor decision making due to hunger is an alternative hypothesis. These traces represent the first reported examples of reverse gastropod drill holes from the fossil record, and the first attributed to Naticidae. Compared to other types of failed predation (incomplete drill holes and drill holes in multiply-drilled specimens) in the two assemblages studied, reverse drill holes are rare (< 1% of drill holes). This result implies that the driller's sensory and decision-making processes were generally reliable at distinguishing dead from live prey.

Distribution, size composition and feeding of the barred snailfish <I>Crystallias matsushimae</I> (Liparidae) in the Russian zone of the Sea of Japan

The results of studying the bathymetric and spatial distribution of the barred snailfish Crystallias matsushimae are presented according to bottom trawl surveys in the Russian waters of the Sea of Japan. The species does not form dense aggregations, although it is not as rare as was previously thought: in bottom trawl catches on the continental slope, the frequency of its occurrence is about 30%. The main areas of the species aggregations are the western part of the Peter the Great Gulf and the deep-water section of the Tatar Strait between the mainland and Sakhalin Island. Despite the relatively wide range of water temperature and depths at which the snailfish was found in catches, the species prefers rather narrow thermal and bathymetric ranges: 0.6–1.5°C and 200–500 m. Mysids, amphipods and decapods dominate in the diet.

Shedding Light on the Italian Mesophotic Spongofauna

An analysis of 483 remotely operated vehicle (ROV) dives carried out along the Italian coast on hard substrata at mesophotic depths (40–200 m) allowed an overview of the rich sponge diversity (53 taxa) of the deep continental platform to be obtained for the first time. About 40% of the potential actual species diversity was recognisable using ROV, suggesting that this group is among the richest yet underestimated using this technology in contrast to other megabenthic taxa. Additionally, the study allowed us to gather data on the current basin-scale distribution and bathymetric limits of five common and easily identifiable demosponges with up to 55% occurrence in the explored sites: Aplysina cavernicola, the group Axinella damicornis/verrucosa, Chondrosia reniformis, Foraminospongia spp., and Hexadella racovitzai. Four of these latitudinal distributions were characterised by high occurrence in the Ligurian Sea and a progressive decrease towards the south Tyrrhenian Sea, with an occasional second minor peak of occurrence in the Sicily Channel. In contrast, Foraminospongia spp. showed a maximum occurrence on the offshore reliefs and a second one in the North–central Tyrrhenian Sea, while it was almost absent in the Ligurian Sea. Trophic and biogeographic reasons were discussed as possible causes of the double-peak distributions. The vertical distributions support a more consistent occurrence of all considered taxa in deeper waters than previously known. This suggests that they may more typically belong to the mesophotic realm than the shallow waters, owing to a more extensive sampling effort in the deeper depth range. The five target taxa are typical or associated species of seven reference habitats in the recently revised UNEP/SPA-RAC classification. However, they may create such dense aggregations that they should be listed as new facies in the abovementioned classification.

Environmental niche, spatial distribution and size structure of shelf-dwelling populations of the gorgonian Eunicella cavolini (Koch, 1887) in NW Mediterranean

Extensive knowledge exists about the ecology of gorgonian species dwelling in coastal areas of the Mediterranean, but less information is available regarding populations found in deep circalittoral and bathyal environments. In recent years, the use of marine imaging technology has led to the discovery of dense coral gardens below SCUBA depths. This is the case of Eunicella cavolini (Koch, 1887) populations dwelling on the continental shelf off Cap de Creus (northwestern Mediterranean), an area included in a Site of Community Importance (SCI) of the Natura 2000 Network. We characterized the environmental niche of this species using a combination of density data extracted from 60 underwater video transects (80–400 m depth) and a set of environmental factors of a geomorphologic, oceanographic and human nature. Populations of E. cavolini develop within a restricted combination of environmental conditions, predominantly in areas of the mid continental shelf (95–110 m depth) characterized by a mixture of substrates (gravels, pebbles and rocks) with intermediate yearly average bottom current velocities (0.11–0.13 m s−1) and where no records of bottom trawling activity were registered in the years prior to the surveys. The species forms dense aggregations that average 6–8 col·m−2, with local high-density peaks above 15 col·m−2. Areas suitable for the development of E. cavolini were modelled by means of a Random Forest algorithm, which predicted that an area extending over 14 ha could potentially host populations with densities over 5 col·m−2. Bottom current velocity emerged as the most important factor determining the spatial distribution of the species, followed by depth and presence of rocks. Colony height measurements indicated that populations are dominated by small-to-medium sized colonies, with average colony height positively correlated with gorgonian density. The reduced average colony height observed might respond to the strong bottom current regime characteristic of Cap de Creus, but also to the increased likelihood of larger colonies to be captured as by-catch by trammel nets, a common type of fishing gear used in the area. This study provides relevant information about the ecology of E. cavolini populations dwelling on deep circalittoral habitats, useful for policymakers when formulating specific management measures to foster the conservation of this species inside the SCI. Additionally, the data provided could assist on the restoration actions already taking place in Cap de Creus, and be used as baseline data to monitor the evolution of E. cavolini populations through time once management plans are implemented.

Geosynthetic-stabilized aggregate: quantitative modulus evaluation via Bender Element

Geosynthetics, mainly geogrids and geotextiles, are commonly used to mechanically stabilize unbound aggregate layers in paved road applications. They provide lateral restraint to aggregates to initially increase the layer modulus during construction and minimize its time-dependent decrease under vehicular traffic loading. Different types of geosynthetics may provide different improvement mechanisms and stiffness enhancement levels. Quantitative evaluation of various stabilization geosynthetics is presented herein to compare modulus improvement trends and help incorporate geosynthetic benefits into state-of-the-art mechanistic-empirical (M-E) pavement design procedures. Five geogrids (three extruded, one woven, and one welded) and two geotextiles (one woven and one nonwoven) were studied with a dense graded aggregate in laboratory triaxial testing. Geosynthetics were placed at specimen mid-height and three pairs of Bender Element (BE) sensors were placed at various heights above the geosynthetic to collect shear waves and quantify the degree of mechanical stabilization during resilient modulus testing. While resilient moduli did not distinguish effectiveness of different geosynthetics, shear wave measurements could clearly show local stiffness increases achieved with geosynthetic inclusions. Meanwhile, trends observed in shear modulus profiles at various distances from the geosynthetic, when compared to that of control specimen, properly established the modulus enhancement level achieved in mechanical stabilization with geosynthetics.

In-situ observations of gelatinous zooplankton aggregations in inshore and offshore Arctic waters

Gelatinous zooplankton (GZ), play a crucial role in marine food webs, nutrient cycling, and carbon sequestration, however, quantifying their abundances remains challenging due to their delicate body structure, complex life cycles and variable population dynamics. Their tendency to form sporadic, large-scale aggregations further complicate the differentiation between true ecosystem alterations and stochastic variations in their abundance. In the Arctic Ocean, our understanding of GZ aggregations remains generally incomplete. Using in-situ observations from a towed pelagic camera system, we assessed the diversity and vertical distributions of GZ in fjord and offshore environments in northern Norway and the Svalbard archipelago. We found that Atlantic water masses harbored the highest GZ abundance, while intermediate waters showed the highest diversity. We documented dense aggregations of Beroe spp. in Van Mijenfjorden in Svalbard (observed during ascent of the camera system, not quantified in ind. m−3) and Bolinopsis infundibulum in the open Barents Sea (> 2.67 ind. m−3 at 100 m). Other observed taxa included the hydrozoans Aglantha digitale, Melicertum octocostatum, Solmundella bitentaculata, Pandeidae sp. and Physonectae spp., the scyphozoan Cyanea capillata and the ctenophores Mertensia ovum and Euplokamis sp. By linking the vertical distribution and observations of local aggregations with physical and biotic factors, we described the potential drivers of the distributional patterns observed. Towed camera surveys contribute to accurate in-situ observations, thereby improving our understanding of GZ aggregations and distributions in the Arctic Ocean.

Efficient removal of basic yellow 28 dye from water using facilely synthesized ZnO and Mg3B2O6 nanostructures

Basic yellow 28 dye, used extensively in the textile and leather industries, poses significant environmental and health risks, including allergic reactions, skin irritation, and respiratory problems. This study reports the Pechini sol-gel synthesis of novel ZnO/Mg3B2O6 nanostructures for the decontamination of basic yellow 28 dye from aqueous solutions. The nanostructures were synthesized by calcining at 650 and 850 °C for 5 h, producing ZM650 and ZM850, respectively. The average crystallite sizes were 39.28 nm for ZM650 and 51.03 nm for ZM850. BET surface areas were 70.71 m2/g for ZM650 and 48.13 m2/g for ZM850. FE-SEM and HR-TEM analyses revealed distinct morphological structures, with ZM650 exhibiting a dense aggregation of rod-like particles and ZM850 showing larger clusters. The maximum adsorption capacities were 381.68 mg/g for ZM650 and 303.03 mg/g for ZM850. The optimum adsorption was observed at a pH of 10, a contact time of 70 min, and a temperature of 298 K. Regeneration using a 6 M HCl solution demonstrated efficient reusability over five cycles. The adsorption process followed pseudo-second-order kinetics and the Langmuir isotherm, indicating monolayer adsorption. Also, the adsorption process was found to be physical and exothermic.

A Large Model-Derived Algorithm for Complex Organoids with Internal Morphogenesis and Digital Marker Derivation.

Automated segmentation and evaluation algorithms have been demonstrated to enhance the simplicity and translational utility of organoid technology. However, there is a pressing need for the development of complex organoids that possess epithelium environmental elements, dense regional cell aggregation, and intraorganoid morphologies. Nevertheless, there has been limited progress, including both the construction of data sets and the development of algorithms, in the use of user-friendly microscopy to address such complex organoids. In this study, a data set of bright-field and living cell fluorescence images in paired forms and with temporal variance was constructed using droplet-engineered lung organoids. Additionally, a large model-based algorithm was developed. Both the organoid contours and intraorganoid morphologies were included in the data set, and their physical parameters were included and screened to form multiplex digital markers for organoid evaluation. The algorithm has been demonstrated to outperform existing methods and is therefore suitable for the evaluation of complex organoids. It is expected that the algorithm will facilitate the successful demonstration of AI in organoid evaluation and decision-making regarding their status.

Larval dispersal and physical connectivity of Pheronema carpenteri populations in the Azores

The study of larval dispersal and connectivity between deep-sea populations is essential for the effective conservation and management of deep-sea environments and the design and implementation of Marine Protected Areas. Dense sponge aggregations, known as “sponge grounds”, are a key component of marine benthic ecosystems, by increasing the structural complexity of the sea floor and providing structure and habitat for many other species. These aggregations are characteristic of the Azores deep-sea environment. These sessile organisms rely primarily on larval dispersal for their reproduction. Connectivity between specific Pheronema carpenteri sponge aggregations in the Azores was studied using a 3-D biophysical dispersal model. Different biological trait scenarios were analyzed, considering spawning seasonality and pelagic larval duration. Model results indicate that regional circulation patterns drive larval dispersion, shaping population connectivity of P. carpenteri sponge aggregations in the Azores, particularly among aggregations in the Central Group of Azorean islands. Some areas present high retention rates, receiving larvae from several sponge aggregations while also being important larval source aggregations. In contrast, aggregations from the Eastern Group may be isolated from the others. Larval dispersal and connectivity patterns were analyzed concerning the current configuration of Marine Protected Areas (MPAs) in the Azores. The results underscored the importance of maintaining protection efforts in existing MPAs and identified stepping-stone locations and specific sites where additional measures could enhance species connectivity in the Azores.

DEVELOPMENT OF SYSTEMIC MASTOCYTOSIS AFTER BONE MARROW TRANSPLANTATION FOR AN ACUTE MYELOID LEUKEMIA: DONOR DERIVEN DISEASE OR SYSTEMIC MASTOCYTOSIS WITH AN ASSOCIATED MYELOID NEOPLASM

Abstract Introduction/Objective Systemic mastocytosis may have variable presentation ranging from an indolent disease to an aggressive form. Systemic mastocytosis with an associated myeloid neoplasm can occur simultaneously, or within an interval of a myeloid neoplasm and should meet the diagnostic criteria of both entities. Methods/Case Report Herein, we present a patient with history of acute myeloid leukemia with KMT2A(11q23) amplification who initially underwent an allogeneic hematopoietic stem cell transplantation from a matched sibling donor. One year later, the patient developed isolated central nervous system relapse, as well as evidence of molecular relapse in the bone marrow and underwent a second allogeneic transplantation, but this time, from a matched unrelated donor. The 100 days post second transplant bone marrow biopsy was negative for involvement by acute myeloid leukemia and the chimerism study revealed evidence of total engraftment with 100% donor cells. Additionally, Fluorescence in situ hybridization analysis detected no evidence of KMT2A amplification. However, morphologic examination of the bone marrow biopsy demonstrated involvement by systemic mastocytosis with multiple dense aggregates of CD117 and tryptase positive mast cells showing spindled cell morphology. Mast cells were positive for CD25 and demonstrated negative expression of CD2 and CD30. PCR analysis of the peripheral blood did not detect evidence of KIT mutation, but serum tryptase was elevated. Results (if a Case Study enter NA) NA Conclusion This case highlights a rare instance of systemic mastocytosis in the setting of remission from an acute myeloid leukemia in a post transplantation bone marrow and represents a diagnostic challenge. While development of systemic mastocytosis in a patient with prior history of an acute myeloid leukemia suggests the possibility of systemic mastocytosis with an associated myeloid neoplasm, some other features including the complete remission and total engraftment of the post transplantation bone marrow with 100% donor cells, raise the possibility of a donor driven disease.

The geomorphic work of the European mole (Talpa europaea): Long‐term monitoring of molehills using structure‐from‐motion photogrammetry

AbstractMoles—small insectivorous mammals of the family Talpidae—are widespread across the Northern Hemisphere. These subterranean mammals are easily detected through the mounds, or molehills, they construct as surface bioproducts of tunnel systems excavated underground. The dense aggregation of these bioconstructions in a range of environments (e.g., floodplains, woodland, coastal dunes and upland regions) indicates that moles may play an important role in sediment systems. However, compared with other fossorial mammals (e.g., gophers and rabbits), the impact of moles as direct and indirect biogeomorphic agents is poorly understood. Furthermore, little is known about how molehills develop and degrade over time or how long they persist as landscape features. By examining molehills created by the European mole (Talpa europaea) over 4 months on a floodplain in Oxfordshire, UK, we provide a quantitative assessment of how these landforms evolve over time and space. Through the creation of high‐resolution digital elevation models (DEMs) using structure‐from‐motion (SfM) photogrammetry, we derive a variety of metrics describing molehill morphology and produce a detailed record of how molehills change at weekly time intervals. In addition, measurements of molehill volume are used to estimate the excavation rate of moles over a month. Findings show that (i) molehills are dynamic landforms that change in size and shape in response to phases of construction, collapse, erosion and rebuilding; (ii) rates of degradation are influenced by soil characteristics and seasonal weather conditions; (iii) molehills can persist as landscape features for several months; and (iv) moles are capable of moving a substantial volume of sediment in highly active areas (3.89 m3 ha−1 month−1). Future work is now needed to determine the geomorphic impact of T. europaea over larger spatial scales (e.g., river catchments) and longer timescales (e.g., years–decades) to determine its importance in relation to other bioturbators and within the wider sediment system.

Multi-scale input layers and dense decoder aggregation network for COVID-19 lesion segmentation from CT scans

Accurate segmentation of COVID-19 lesions from medical images is essential for achieving precise diagnosis and developing effective treatment strategies. Unfortunately, this task presents significant challenges, owing to the complex and diverse characteristics of opaque areas, subtle differences between infected and healthy tissue, and the presence of noise in CT images. To address these difficulties, this paper designs a new deep-learning architecture (named MD-Net) based on multi-scale input layers and dense decoder aggregation network for COVID-19 lesion segmentation. In our framework, the U-shaped structure serves as the cornerstone to facilitate complex hierarchical representations essential for accurate segmentation. Then, by introducing the multi-scale input layers (MIL), the network can effectively analyze both fine-grained details and contextual information in the original image. Furthermore, we introduce an SE-Conv module in the encoder network, which can enhance the ability to identify relevant information while simultaneously suppressing the transmission of extraneous or non-lesion information. Additionally, we design a dense decoder aggregation (DDA) module to integrate feature distributions and important COVID-19 lesion information from adjacent encoder layers. Finally, we conducted a comprehensive quantitative analysis and comparison between two publicly available datasets, namely Vid-QU-EX and QaTa-COV19-v2, to assess the robustness and versatility of MD-Net in segmenting COVID-19 lesions. The experimental results show that the proposed MD-Net has superior performance compared to its competitors, and it exhibits higher scores on the Dice value, Matthews correlation coefficient (Mcc), and Jaccard index. In addition, we also conducted ablation studies on the Vid-QU-EX dataset to evaluate the contributions of each key component within the proposed architecture.

Mass occurrences of Sandeels (Ammodytes spp.) causing aggregations of diving ducks

In autumn 1999, large, compact flocks of foraging diving ducks, particularly Common Eiders Somateria mollissima, were observed within and at the mouth of Trondheimsfjord in Central Norway. Some of these aggregations were at places previously not known as particularly rich feeding grounds. This situation continued through the winter, and still existed in March 2000. Investigations on these feeding grounds showed that the only possible prey species occurring in significant quantities was Sandeel (only Ammodytes tobianus was verified). Although most of the fish were swallowed before the birds reached the surface, some ducks (including Velvet Scoter Melanitta fusca and Goldeneye Bucephala clangula) were observed eating Sandeels. Sandeel populations fluctuate in size annually and shoals are very patchily distributed. Consequently, the very variable occurrence in time and space of this food resource may occasionally bring about unusually dense and patchy aggregations of various species of diving ducks. Due to the specific habitat requirements of the Sandeel, these aggregations may also occur at localities that are not generally preferred feeding grounds for diving ducks, as was the case here. These findings may be relevant for some monitoring projects involving populations of diving ducks in marine environments.

Effect of different heat inputs on the microstructure and mechanical properties of the laser welded joint of CLF-1 steel

Abstract In this study, we examined the effects of various heat inputs on the microstructure and mechanical properties of the laser-welded joints of CLF-1 low-activation ferritic/martensitic steel medium-thick plates, which are used in the Test Blanket Module (TBM). The results indicate that under four different welding heat inputs (2727 J/cm, 3000 J/cm, 3563 J/cm, and 4500 J/cm), the weld microstructure is primarily composed of a large amount of lath martensite and a small amount of δ-Fe. As the heat input increases, the average width of lath martensite in the weld microstructure progressively increases, while the average volume fraction and width size of δ-Fe experience a significant increase. When the heat input surpasses 3563 J/cm, δ-Fe exhibits a dense aggregation. The tensile properties of the joints created under different heat inputs are superior to those of the base material. At the lowest heat input, the maximum impact toughness of the weld reaches 40 J.

Acoustic Wave-Driven Microdroplet Enrichment for Surface-Enhanced Raman Spectroscopy Detection

Surface-enhanced Raman scattering (SERS) holds significant potential across environmental monitoring, materials science, and biomedical applications. However, challenges regarding ultra-sensitive detection and repeatability are bottlenecks for practical applications, especially in terms of detection uniformity. In this study, we utilized surface acoustic waves (SAW) in conjunction with Raman spectroscopy to actively enrich 5 μL of 50 nm gold nanoparticles (AuNPs), thereby achieving innovative SERS-active sensing. This dynamic enrichment process enables the dense and uniform aggregation of AuNPs in droplets, thereby facilitating reliable ultrasensitive detection. The SAW system was further optimized through hydrophobic surface treatment. Using 4-mercaptobenzoic acid as a probe analyte, our SAW-SERS method successfully detected concentrations as low as 10−8 mol/L. The surface acoustic waves had the capability to significantly amplify Raman signal intensity up to 100 compared to conventional drying methodologies. This SAW-induced AuNP clustering technology offers a rapid, label-free SERS sensing method characterized by exceptional sensitivity and uniformity.