Particle Analysis Research Articles

Improved semi-theoretical correlation to predict the Sauter mean diameter of swirl cups

The spray downstream of swirl cups involves complex two-phase flow. Comprehensively, understanding the flow physics of the spray to accurately predict the characteristics of the swirl spray is crucial for developing next-generation low-emission gas turbine combustors. The Sauter mean diameter (SMD) of the spray is an important design parameter in a gas turbine combustor, and the semi-theoretical method is among the most widely used approaches for predicting the SMD of atomizers. Of the available semi-theoretical models for predicting the SMD of prefilming-type atomizers, Shin's phenomenological three-step atomization (PTSA) model is a physics-based correlation. The PTSA model comprises three submodels: those of the pressure-swirl spray, impingement and film formation, and aerodynamic breakup. Based on similar physical mechanisms, the PTSA model can effectively predict the SMD for the spray shear layer of swirl cups. In this study, a new model, called the PTSA-V model, is proposed by introducing the viscosity of the liquid to the three submodels of PTSA. Additionally, the submodel of impingement and film formation was reconstructed, using a simplified model of a round water jet impinging on a cylindrical wall to predict the thickness of the liquid film on the Venturi surface. Experiments were carried out on a swirl cup under different pressures and temperatures of fuel as well as varying pressure drops in the air by using a two-component phase Doppler particle analyzer. The resulting uncertainty in predictions of the PTSA-V model was lower than ±7.4% under the 26 operating conditions considered here, compared with an uncertainty of ±20% in the outcomes of PTSA. Uncertainty in predictions of PTSA-V was lower than ±15% when it was applied to SMD data downstream of the swirl cup from the literature.

Acceleration of Pick‐Up Ions in the Martian Magnetosheath: A Tianwen‐1 Case Study

AbstractThis study delves into a Pick‐Up Ion (PUI) event captured by the Mars Ion and Neutral Particle Analyzer aboard Tianwen‐1, revealing a faster acceleration than expected within the Martian magnetosheath. This event suggests the presence of a convection electric field considerably stronger than that typically observed in the solar wind. Through Magnetohydrodynamic simulation, we identified two regions of intensified convection electric fields within the inner magnetosheath, prominently manifested at mid to high solar zenith angles (SZA = 40°–70°) in the X‐Z plane of the Mars Solar Electric field coordinates. Tianwen‐1 observed that the peak of the electric field strength, up to five times of that in the solar wind, is located at the upper edge or within the Magnetic Pileup Boundary. Further study by test particle simulations showed acceleration by the electric field effectively doubles the energy gain of PUIs, in comparison to scenarios absent of this extra acceleration. It is revealed that the presence of such electric field regions within the Martian magnetosheath is a prevailing feature, shaped by the solar wind's interaction with Mars and modulated by the planet's rotating crustal magnetic fields.

Orifice section velocity fitting method and its application in flash spray research

Although spray technology is widely used, research on spray flow is limited by the complexity of its flow field. To simplify the spray simulation, this work proposed an orifice section velocity fitting method, which can simplify the calculation of the flow field inside the nozzle by using a set of special velocity fitting equations as boundary conditions. For the application and verification of the method, the characteristics of methyl nonafluorobutyl ether (HFE7100) flash spray under temperature influence were experimentally studied in this paper using phase Doppler particle analyzer equipment and compared the results of simulation and experiment. The comparison results show that the simulation and experimental results of the spray axial velocity distribution have good consistency at different temperatures. The simulation results show that the swirling flow in the orifice is stronger when the temperature is lower than the boiling point and the spray velocity isosurface is conical. The swirling flow in the nozzle is attenuated by flash evaporation when the temperature increases above the boiling point, while the spray velocity isosurface changes to a bell shape. The experimental results show that the spray velocity increases with increasing evaporation caused by increasing temperature and that the spray axial velocity distribution also changes from a saddle shape to a single peak shape. The spray droplet size increased significantly under the influence of flash evaporation, but the spatial distribution maintained a saddle shape. This study can provide a reference for spray simulation analysis and the study of flash spray characteristics.

Analysis of Cu-decorated Ti particles as a reinforcement for AZ91 alloys prepared using the powder metallurgy method

Magnesium (Mg) matrix composites (Mg-MMCs) with high strength and ductility properties are crucial for the development of lightweight automobiles. In this study, a novel method is proposed for fabricating Mg-MMCs by incorporating nanocopper (Cu) decorated titanium (Ti) particles (Cu@Ti) to reinforce AZ91 alloys. The in-situ generation of the AlCuMg phase at the interface between the Ti particles and the Mg matrix enhances interface integration and promotes the formation of massive twins. The 5.0 wt% Cu@Ti/AZ91 composite exhibits notable mechanical properties, with a yield strength of 238 MPa, ultimate tensile strength of 368 MPa, elongation of 12%, and modulus of elasticity of 46 GPa. These values represent increases of 8.9%, 5.3%, 50.0%, and 2.0%, respectively, compared to those of AZ91 alloys. The strengthening mechanism is mainly attributed to grain refinement strengthening, thermal expansion coefficient mismatch strengthening, Orowan strengthening, and load transfer strengthening. The plasticity improvement benefits from the optimization of the interface structure, grain refinement and twin formation.

Sampling, quantification and mathematical modeling in agricultural spray drift: A review

An effective spray of agrochemicals is inevitable for crop production for viable agriculture. Spraying inherently suffers from drift, which has always been one of the major concerns in agriculture, affecting the intent of agrochemical spraying and posing serious environmental hazards. Complete elimination of spray drift is impractical under field conditions but can be minimized using precision spraying techniques. Agricultural spray drift has several detrimental effects, such as environmental damage, polluting water bodies, human and animal health risks, chemical exposure, and economic losses, and may also lead to conflicts between neighboring farmers. Hence, the assessment of spray drift is a salient part of the design process of plant protection equipment to achieve maximum deposition in both chemical and biological pesticide applications. The different methods used to study the drift of a sprayer include test bench, wind tunnel and phase Doppler particle analyzer (PDPA) methods. In the field-level assessment, the fluorometric tracer sampling method conforming to ISO-22866:2005 was used. Plume dispersion, particle tracking and computational fluid dynamics (CFD) are the major mathematical modeling approaches for spray drift simulation studies. Among various methodologies and techniques, an appropriate method for spray drift assessment should be adopted in accordance with factors such as crop parameters, mode of application, and environmental conditions.

Small microplastic ingestion by the calanoid Centropages furcatus in the Gulf of Thailand

Microplastics could be ingested by many organisms, including zooplankton, involving bioaccumulation and biomagnification mechanisms a cross food webs. The information about microplastic ingestion by zooplankton keeps increasing worldwide. However, it is still limited for particle sizes under 300 μm (small microplastics, SMPs) and in areas such as Southeast Asia, which is considered one of the hotspots for plastic debris. This study aimed to characterize the size, shape, and polymer types of the SMPs ingested by the copepod Centropages furcatus in Si Chang Island (upper Gulf of Thailand). The study spans offshore and coastal waters, with data collected across wet, intermediate, and dry seasons. Using a semi-automated technique for micro-FTIR (Fourier-transform infrared) scanning spectroscopy for particle analysis, we found ingested SMPs in all samples. A total of 750 individuals of the calanoid Centropages furcatus were analyzed, finding 309 plastic particles and an average ingestion value of 0.41 ± 0.13 particles ind−1, one of the highest recorded values. All the particles were fragments, with a predominant size under 50 μm, and polymer types as Polypropylene (PP, 71 %), followed by Ethylene-Propylene-Diene-Monomer (EPDM, 16 %) and Polyethylene (PE, 7 %). Up to 470.2 particles m−3 were estimated to be retained by this calanoid species and potentially available for trophic transfer. The effect of rainfall on SMPs ingestion was inconclusive, with a non-significant observed tendency to higher ingestion values near the coastal area than offshore area, suggesting a decrease in particle exposure due to the runoff effect. Nevertheless, future studies should increase the frequency of surveys to arrive at better conclusions.

Assessing the Effect of Surface Coating on the Stability, Degradation, Toxicity and Cell Endocytosis/Exocytosis of Upconverting Nanoparticles

Lanthanide-doped up-converting nanoparticles (UCNPs) have emerged as promising biomedical tools in recent years. Most research efforts were devoted to the synthesis of inorganic cores with the optimal physicochemical properties. However, the careful design of UCNPs with the adequate surface coating to optimize their biological performance still remains a significant challenge. Here, we propose the functionalization of UCNPs with four distinct types of surface coatings, which were compared in terms of the provided colloidal stability and resistance to degradation in different biological-relevant media, including commonly avoided analysis in acidic lysosomal-mimicking fluids. Moreover, the influence of the type of particle surface coating on cell cytotoxicity and endocytosis/exocytosis was also evaluated. The obtained results demonstrated that the functionalization of UCNPs with poly(isobutylene-alt-maleic anhydride) grafted with dodecylamine (PMA-g-dodecyl) constitutes an outstanding strategy for their subsequent biomedical application, whereas poly(ethylene glycol) (PEG) coating, although suitable for colloidal stability purposes, hinders extensive cell internalization. Conversely, surface coating with small ligand were found not to be suitable, leading to large degradation degrees of UCNPs. The analysis of particle’ behavior in different biological media and in vitro conditions here performed pretends to help researchers to improve the design and implementation of UCNPs as theranostic nanotools.

New insights into the sources of atmospheric lead reaching the Arctic by isotopic analysis of PM10 atmospheric particles and resuspended soils

Lead concentration, crustal enrichment factor, and isotope ratios (including those with the less abundant 204Pb) have been measured in PM10 samples collected at Ny-Ålesund (Svalbard Islands) from October 2018 to November 2020, including, for the first time, the autumn and winter seasons. In addition, resuspended soil samples from Svalbard Islands, Iceland, and Alaska were prepared and analysed to provide reference values for local and short-range potential source areas, and back-trajectory analysis was applied to corroborate the findings based on the Pb isotopic signatures.Results showed that the atmospheric Pb concentration reached its maximum in January, progressively decreased until August, remained low until November, and increased again in December. The Pb isotopic composition also showed a clear temporal variation, indicating a shift in the Pb sources with the changing seasons, in agreement with the back-trajectory analysis results. Lead in PM10 samples collected from November to May was entirely (>99%) anthropogenic, and it likely derived from the mining activities in East Kazakhstan and the Altai region, specifically at Leninogorsk (now Ridder). In contrast, the Pb isotopic composition of particulate samples collected from June to October reflected mixed anthropogenic contributions from the North-East USA and Canada, with a significant contribution from natural sources.

Structural insights into the calcium-coupled zinc export of human ZnT1.

Cellular zinc (Zn2+) homeostasis is essential to human health and is under tight regulations. Human zinc transporter 1 (hZnT1) is a plasma membrane-localized Zn2+ exporter belonging to the ZnT family, and its functional aberration is associated with multiple diseases. Here, we show that hZnT1 works as a Zn2+/Ca2+ exchanger. We determine the structure of hZnT1 using cryo-electron microscopy (cryo-EM) single particle analysis. hZnT1 adopts a homodimeric structure, and each subunit contains a transmembrane domain consisting of six transmembrane segments, a cytosolic domain, and an extracellular domain. The transmembrane region displays an outward-facing conformation. On the basis of structural and functional analysis, we propose a model for the hZnT1-mediated Zn2+/Ca2+ exchange. Together, these results facilitate our understanding of the biological functions of hZnT1 and provide a basis for further investigations of the ZnT family transporters.

Automated SEM analysis of particles in Hanford tank waste

Multiple bench-scale filtration campaigns of Hanford tank waste supernatant on a backpulseable dead-end filtration skid have provided greater insight into the solids that cause fouling and reduce filter performance. The solids collected during each campaign were concentrated from the backpulse solutions and examined using automated particle analysis (APA) methods with scanning electron microscopy and X-ray energy dispersive spectroscopy to categorize particle types and their morphological characteristics. We show that with APA, thousands of particles can be analyzed to provide accurate insight into the phases that may be impacting filter performance.

Research on the Grinding Process of Superhard Particles in the Fluidized Bed Opposed Jet Mill Based on the CFD-DEM Methodology

The process of superhard particle breakage in the grinding zone of the fluidized bed opposed jet mill is investigated using the CFD-DEM (computational fluid dynamics-discrete element method) coupling method with the Tavares UFRJ Breakage Model in the present study. The effects of structural and operational parameters, such as target plate structure, nozzle position, air inlet velocity, and feed rate, on the equipment stress distribution, airflow velocity, pressure field, particle velocity, and cumulative particle size distribution are thoroughly studied to determine the optimal structural and operational parameters. Experimental validation is conducted, including scanning electron microscope (SEM) observation of particle morphology and analysis of particle size distribution of ground product particles. The simulation results indicate that the wear rate of the structure without a target plate is lower than that of the structure with a target plate in the grinding central zone. Therefore, the structure without a target plate is chosen for further investigation. The cumulative particle size distribution after grinding is influenced by nozzle position, air inlet velocity, and feed rate. The particle D50 is positively correlated with nozzle spacing and feed rate, while it is negatively correlated with air inlet velocity. The optimal grinding effect is achieved when the distance between the nozzle and the center of the grinding zone ranges from 52.5 mm to 72.55 mm, the air inlet velocity is 950 m/s, and the feed rate is 10.5 g/s. Through experimental investigation, it has been observed that when the feed rate is 10 g/s, the particle size distribution becomes more uniform. Furthermore, consistent trends in the cumulative particle size distribution in the experiment and simulation results can be found, which validates the present numerical model. It was observed that particles at low feed rates retain certain angular edges, while particle roundness increases at high feed rates.

Isotopic analysis of uranium at the picogram level with single-shot laser induced breakdown spectroscopy

Uranium was measured by laser induced breakdown spectroscopy (LIBS) with a limit of detection of 1.3 picograms with spectral-peak height as the analytical parameter, which shows an improvement of several orders of magnitude compared to other reports in the literature. The improvement is a result of optimizing the choice of the U analytical line, the system hardware, and the light collection and detection efficiency. The research established properties of U line emission (intensity, signal-to-background ratio, isotopic splitting, and spectral interferences) to select an optimum wavelength for analysis. The samples were mock particles from dried, monodispersed U solution droplets (∼65 pL in volume) deposited on Si wafers. LIBS emission spectra from several 235U-enriched samples were measured to demonstrate the performance for isotopic analysis. For isotopic measurements, two masses for total U, 100 pg and 325 pg, were studied. The 235U: 238U isotopic ratio was obtained by peak fitting the LIBS spectra without requiring calibration with the use of enriched standards. Depending on the total U mass and the 235U enrichment, typical relative standard deviations of the isotopic analysis ranged from several percent down to about 1%. Further, the developed method and the reported analytical performance were all based on single-shot LIBS. Overall, the study highlights the potential of LIBS as a robust and sensitive technique for isotopic analysis of U-containing particles.

Synthesis, Characterization and Dissolution behavior of Nitrides of U-Zr and U-Pu-Zr metallic alloy fuels for Aqueous reprocessing

The aqueous based PUREX process is an alternate choice to pyro-reprocessing of metallic alloy fuels (U-Zr/U-Pu-Zr). Direct dissolution of metallic alloy fuels in a nitric acid medium is not feasible due to vigorous reaction exhibited by the alloys when exposed to this medium. Conversion of metallic alloys into their oxides is a challenging method due to poor dissolution of oxides in nitric acid. Excellent dissolution of nitrides compared to oxides of metallic alloy fuels lead to exploit the nitride route for aqueous reprocessing. Hence, a novel method was adopted to prepare the nitrides of unirradiated U-Zr and U-Pu-Zr alloys via hydridation using UH3, as source-cum-getter instead of hydrogen cylinder. In this context, nitrides of unirradiated U-Zr/U-Pu-Zr metallic alloys were prepared by nitridation via hydridation. Initially, nitrides of U and Zr metals were synthesized and the formation of ZrN and U2N3 and UN phases were confirmed by powder X-ray diffraction measurements. Subsequently, nitrides of unirradiated U-Zr and U-Pu-Zr alloys were synthesized and characterized by X-ray diffraction, scanning electron microscopy and particle analyzer. The dissolution behavior of nitrides of Zr, U, U-Zr and U-Pu-Zr alloys were examined in nitric acid (12 M) medium under reflux conditions at 383 K for 8 h. The present study highlights the potential of the nitride route for efficient dissolution of actinides (U and Pu) and it is very important to develop flow sheets for the aqueous reprocessing of metallic alloys fuels.

Precipitation mechanism of abrasive particles in magnetorheological polishing fluid and experimental verification

This study aims to address the issue of poor workpiece surface machining quality due to inadequate abrasive particle precipitation during the processing of magnetorheological polishing fluid. The paper employs magnetic dipole theory and molecular dynamics theory to establish a microdynamics model for magnetorheological polishing fluid and conducts kinematic and dynamic analyses of magnetic and abrasive particles. The chaining process of magnetic particles in magnetorheological polishing fluid was simulated under an external magnetic field, and the precipitation process of abrasive particles under the action of magnetic particles was simulated and analyzed. Furthermore, we established a microscopic observation experimental platform for magnetorheological polishing fluid and verified the precipitation law of abrasive particles under the action of dynamic magnetic field. The study findings indicate that the magnetic particles will form a chain structure, when the rotating magnetic field has an effect on the magnetorheological polishing fluid, and the abrasive particles will precipitate from the magnetorheological polishing fluid and adhere to the upper end of the magnetic chain. Moreover, the precipitation rate of abrasive particles is also affected by the magnetic field strength, the volume fraction of magnetic particles, and the rotating magnetic field speed, with the abrasive particles’ precipitation rate specifically increasing with higher magnetic field strength. At a magnetic field strength of 100 kA/m, the abrasive precipitation rate reaches 80 % in approximately 90 s, which increases to 80 % in only 60 s at a magnetic field strength of 200 kA/m. Additionally, with the increase of magnetic particle volume fraction, the precipitation rate of abrasive particles decreases. Within the first 40 s of the test, the magnetic particle volume fraction increases from 10 % to 30 %, and the precipitation rate of abrasive particles decreases by about 11 %. Similarly, the abrasive precipitation rate is affected differently by the rotating magnetic field speed. As the rotating magnetic field speed increases, the abrasive precipitation rate shows a trend of first increasing and then decreasing. When the rotating magnetic field speed increases from 20 r/min to 40 r/min, the abrasive precipitation rate of the first 40 s increases by about 25 %. When the speed continues to increase to 60 r/min, the precipitation rate of abrasive particles gradually decreases.

Structural and electrochemical elucidation of biocatalytic mechanisms in direct electron transfer-type D-fructose dehydrogenase

D-Fructose dehydrogenase (FDH) from Gluconobacter japonicus NBRC3260, a membrane-bound heterotrimeric flavohemoprotein capable of intense direct electron transfer (DET)-type bioelectrocatalysis, was investigated using protein engineering, electrochemistry, structural biology, and bioinformatics. DET-type reactions have led to an increase in energy efficiency, biocompatibility, and design freedom in bioelectrochemical devices, such as biofuel cells, biosensors, biosupercapacitors, and bioreactors. However, one of the greatest challenges for this reaction is the limited number of the applicable enzymes. The creation of variants with altered substrate specificities using template enzymes is a promising solution to address this problem. For creating variants using FDH as a template, it is important to understand the biocatalytic mechanisms. Recently, the structure of FDH has been analyzed using cryo-electron microscopy (cryo-EM) single particle analysis, and the three amino acid residues (N1146, H1147, and N1190) may be critical for substrate recognition by FDH. In this study, we aimed to understand the mechanisms of the biocatalytic reaction of FDH and discuss the roles of these residues. In addition, we validated the structures of the in-silico variants by comparing them to the cryo-EM structures. Furthermore, for the variants of N1146 involved in D-fructose recognition, we have verified the changes in specificity for other substrates.

Automatic Particle Recognition Based on Digital lmage Processing

The purpose of the research is to develop and compare various methods and algorithms for effective particle analysis based on their visual characteristics. Тhe purpose of this article is to develop and compare various methods and algorithms for effective particle analysis based on their visual characteristics. Тhe paper considers two fundamentally different approaches: the analysis of grayscale gradients and the machine learning method.Methods.Тhe research methodology includes the analysis of particle images obtained by precipitation from colloidal solutions after laser ablation and images of powder particles for selective laser melting. Тhe materials were obtained using a Quanta 200 3D electron microscope (FЕ/). For the analysis, threshold brightness binarization, contour recognition methods by the Kenny operator and the Hough algorithm are used to combine boundary points into connected contours. For comparison, the U-Net neural network solution was used, and a dataset generator was created to train the neural network. Hand-cut images of aluminum alloy powder particles and micro and nanoparticles of various metals are used as data for generation.Results.Тhe results of the study show that the Hough method provides recognition of the number of particles at the level of 80%, and the machine learning method achieves 95% accuracy in recognizing the shape of particles. Both methods can be used to analyze microand nanoparticles, including irregularly shaped particles.Conclusion.Тhe findings of the work confirm that neural networks are the optimal solution for automatic particle recognition in digital images. However, in order to create a dataset of sufficient volume, it is necessary to develop a generator of labeled images, which requires a detailed study of the subject area.

Particle analysis of surgical lung biopsies from deployed and non-deployed US service members during the Global War on Terrorism.

The role that inhaled particulate matter plays in the development of post-deployment lung disease among US service members deployed to Southwest Asia during the Global War on Terrorism has been difficult to define. There is a persistent gap in data addressing the relationship between relatively short-term (months to a few years) exposures to high levels of particulate matter during deployment and the subsequent development of adverse pulmonary outcomes. Surgical lung biopsies from deployed service members and veterans (DSMs) and non-deployed service members and veterans (NDSMs) who develop lung diseases can be analyzed to potentially identify residual deployment-specific particles and develop associations with pulmonary pathological diagnoses. We examined 52 surgical lung biopsies from 25 DSMs and 27 NDSMs using field emission scanning electron microscopy (FE-SEM) with energy dispersive x-ray spectroscopy (EDS) to identify any between-group differences in the number and composition of retained inorganic particles, then compared the particle analysis results with the original histopathologic diagnoses. We recorded a higher number of total particles in biopsies from DSMs than from NDSMs, and this difference was mainly accounted for by geologic clays (illite, kaolinite), feldspars, quartz/silica, and titanium-rich silicate mixtures. Biopsies from DSMs deployed to other Southwest Asia regions (SWA-Other) had higher particle counts than those from DSMs primarily deployed to Iraq or Afghanistan, due mainly to illite. Distinct deployment-specific particles were not identified. Particles did not qualitatively associate with country of deployment. The individual diagnoses of the DSMs and NDSMs were not associated with elevated levels of total particles, metals, cerium oxide, or titanium dioxide particles. These results support the examination of particle-related lung disease in DSMs in the context of comparison groups, such as NDSMs, to assist in determining the strength of associations between specific pulmonary pathology diagnoses and deployment-specific inorganic particulate matter exposure.

Polarization Characterization of Porous Particles Based on DDA Simulation and Multi-Angle Polarization Measurements.

Porous suspended particles are hazardous to human health due to their strong absorption capacity for toxic substances. A fast, accurate, in situ and high-throughput method to characterize the microporous structure of porous particles has extensive application value. The polarization changes during the light scattering of aerosol particles are highly sensitive to their microstructural properties, such as pore size and porosity. In this study, we propose an overlapping sphere model based on the discrete dipole approximation (DDA) to calculate the polarization scattering characteristics of porous particles. By combining scattering calculations with multi-dimensional polarization indexes measured by a multi-angle polarized scattering vector detection system, we achieve the identification and classification of pore-type components in suspended particles. The maximum deviation based on multiple indexes is less than 0.16% for the proportion analysis of mixed particles. Simultaneously, we develop a quantitative inversion algorithm on pore size and porosity. The inversion results of the three porous polymer particles support the validity and feasibility of our method, where the inversion error of partial particles is less than 4% for pore size and less than 6% for porosity. The study demonstrates the potential of polarization measurements and index systems applied in characterizing the micropore structure of suspended particles.

Influence of microplastics and biogenic particles on the size spectra of tropical estuarine and marine pelagic ecosystems

Size spectra analysis has been widely used to study pelagic ecosystems worldwide. It has a solid theoretical and empirical basis and can be used to provide useful information on ecosystem structure and trophic efficiency. The objective of this study was to obtain complete Normalized Biovolume Size Spectra (NBSS), including zooplankton, microplastics, and other suspended particles, along an estuary-shelf gradient. Plankton net samples (300 μm mesh) were obtained in the Rio Formoso Estuary, in Tamandaré Bay and on the continental shelf off Tamandaré, Brazil, during two years (from April/2013 to May/2015). Particles were identified by image analysis (ZooScan) and infrared spectroscopy (FTIR). Generally, NBSS slopes were close to −1 (i.e., between −1.09 and −0.85), except for NBSSz (zooplankton only) in the Estuary (−1.59) and in the Bay (−1.44), where the steepest slopes were observed, due to the importance of small-sized zooplankton in these areas. The NBSSz slope was significantly steeper in the Estuary and in the Bay than on the Shelf. The inclusion of particles into the NBSS (NBSSp) turned the slope significantly less steep in the Estuary and in the Bay. Intercepts were significantly higher in the Estuary than in the other areas, after including particles in the analysis (NBSSp), due to the extremely high total volume of biogenic particles in the estuary. The most relevant impacts of microplastics were detected within the larger size classes (> 2.60 mm Feret length, > 0.58 log10 mm3). In the Estuary, large-sized microplastics were similarly important (in terms of volume) as zooplankton. Large-sized polyethylene and polypropylene were more relevant in the Bay, large-sized nylon fibers on the Shelf (in the rainy season). The present study, a pioneering effort towards a synthetic analysis of zooplankton, microplastics, and other particles, highlights the importance of including non-living particles in size-based studies and ecosystem models.

Seeing is believing: Correlating optoelectronic functionality with atomic scale imaging of single semiconductor nanocrystals.

A unique on-chip method for the direct correlation of optical properties, with atomic-scale chemical-structural characteristics for a single quantum dot (QD), is developed and utilized in various examples. This is based on performing single QD optical characterization on a modified glass substrate, followed by the extraction of the relevant region of interest by focused-ion-beam-scanning electron microscope processing into a lamella for high resolution scanning transmission electron microscopy (STEM) characterization with atomic scale resolution. The direct correlation of the optical response under an electric field with STEM analysis of the same particle allows addressing several single particle phenomena: first, the direct correlation of single QD photoluminescence (PL) polarization and its response to the external field with the QD crystal lattice alignment, so far inferred indirectly; second, the identification of unique yet rare few-QD assemblies, correlated directly with their special spectroscopic optical characteristics, serving as a guide for future designed assemblies; and third, the study on the effect of metal island growth on the PL behavior of hybrid semiconductor-metal nanoparticles, with relevance for their possible functionality in photocatalysis. This work, therefore, establishes the use of the direct on-chip optical-structural correlation method for numerous scenarios and timely questions in the field of QD research.