Size Distribution Measurements Research Articles

Simultaneous measurement of particle size distribution and mixing ratio based on Monte Carlo ultrasonic attenuation model

Abstract Mixed particle systems are commonly employed in industrial processes, where the characterization of particle size parameters and mixing ratio can frequently serve as key indicators in process control and production optimization. A Monte Carlo (MC) model was developed to numerically predict and study the ultrasonic attenuation spectrum characteristics in the polymethyl methacrylate (PMMA)-glass aqueous suspension, and together with the particle swarm optimization (PSO) algorithm, to handle the inverse problem in solving the particle size, distribution width, and mixing ratio. The results of the numerical simulations indicate that there exists a linear relationship between the attenuation coefficient and the mixing ratio, with the particle size exerting a significant influence. Furthermore, the multi-parameter simultaneous inversion also yielded calculation deviations of less than 1%, 3%, and 6% for the mixing ratio, characteristic diameter, and distribution width, respectively, in comparison to their given values. Afterward, a series of experiments were conducted to quantify the particle size and mixing ratio through the analysis of ultrasonic spectra. In spherical PMMA-glass aqueous suspensions, the measurement error for the mixing ratio and particle size parameters are found to be less than 7% and 10%, respectively, when compared to the image method and the given values. Nevertheless, the measurement errors are slightly increased in a non-spherical mixed particle system, where the volume median diameter and mixing ratio are still less than 10%. The MC modeling and PSO algorithm offer the potential to characterize particle size and mixing ratio for mixed particle systems in industrial applications.

Direct measurement of brake wear particles from a light-duty vehicle under real-world driving conditions

Abstract As tailpipe emissions have decreased, there is a growing focus on the relative contribution of non-exhaust sources of vehicle emissions. Addressing these emissions is key to better evaluating and reducing vehicles’ impact on air quality and public health. Tailoring solutions for different non-exhaust sources, including brake emissions, is essential for achieving sustainable mobility. Studying emissions from vehicles in real-world scenarios provides a better understanding of their environmental impact compared to laboratory testing alone. This study presents findings on the direct measurement of brake particles and the characterization of this source of particulate matter in real-world conditions using a mobile laboratory. In situ measurements of particle concentration and size distribution showed good agreement with previous laboratory studies, indicating the suitability of the approach to investigate break particle emissions during real-world operation. The study demonstrates that particle size distributions can vary based on the temperature of the brake disk, which is influenced by the initial braking speed, with significant variations observed between speeds of 60, 80, 100, and 120 km/h. Particles with sizes between 6 and 523 nm were released into the air from the brake system, although it is likely that larger particles were also emitted but not captured due to the upper detection limit of the Engine Exhaust Particle Sizer. During harsh braking events, such as decelerations of 4.2 m/s2 from 120 km/h, a concentration of up 106 (#/cm3) was measured for particles under 8 nm. Moreover, scanning electron microscope analysis revealed that nanoparticles are present in the form of agglomerates, whose shape can change depending on the formation process. Elements present in the particles comprised mainly iron, copper, and aluminium, indicating wear of the brake pad materials and disk components.

Rethinking primary particulate matter: Integrating filterable and condensable particulate matter in measurement and analysis.

The current definition of primary particulate matter (PM) encompasses filterable PM (FPM) and condensable PM (CPM), which are evaluated using two distinct conventional measurement methods: cooling and dilution. While the cooling method exclusively considers the homogenous formation of CPM, the dilution method, closer to real-world conditions, neglects FPM characterization. To overcome this limitation, we propose a doubled-dilution system that enables the parallel characterization of both FPM and primary PM without diverting FPM from the CPM formation pathway. The doubled-dilution system has been investigated from a laboratory scale to a full-scale coal-fired power plant to facilitate simultaneous, real-time measurements of primary PM and FPM size distributions. Moreover, the formation rates of homogeneous and heterogeneous nucleation were compared. The evolution of the primary PM size revealed a bimodal distribution, and the filter-based mass concentration results demonstrated a pronounced preference for heterogeneous reactions (17.6 times higher than homogeneous nucleation). In particular, primary PM emissions were underestimated by up to 65.3% when only homogeneous CPM formation was considered, underscoring the importance of including FPM during primary PM measurements. Considering these results, we advocate adopting the term "primary PM" over "CPM."

Biosynthesis of novel MnO<SUB>2</SUB> nanocapsules via <I>C. spinosa</I> extract and honeybee-derived chitosan: exploring antibacterial and anticancer properties

This investigation delves into the integration of Capparis spinosa extract (CSLe) onto manganese dioxide nanoparticles (MnO2NPs) and chitosan derived from honeybees (CSH) in a nanostructured configuration. The resultant nanocomposites, namely CSLe@MnO2NPs and CSH/CSLe@MnO2NPs, underwent thorough characterization through various analytical techniques. UV-Vis spectroscopy unveiled distinctive features, such as ligand-to-metal charge transfer and photoluminescence, affirming the successful chitosan-functionalization of the MnO2NPs, thereby differentiating them from their pristine counterparts. FTIR spectra corroborated the binding of chitosan and identified crucial molecular functional groups. SEM-EDX analysis revealed the morphological properties, addressing non-uniform sizes in the as-calcined MnO2NPs by the uniform coating of CSH on CSLe@MnO2NPs, while EDX confirmed the presence of essential elements. TEM and SAED provided insights into the spherical morphology, crystalline structure, and lattice planes of these nanoparticles. Size distribution measurements highlighted distinctions between CSLe@MnO2NPs and CSH/CSLe@MnO2NPs. The nanomaterials underwent evaluation for their antimicrobial properties against a spectrum of Gram-negative and Gram-positive bacterial strains, with CSH/CSLe@MnO2NPs exhibiting the highest bactericidal activity. Additionally, they demonstrated low minimum inhibitory concentration (MIC) values, especially against S. aureus (MIC as low as 12.5 µg/ml). Their efficacy extended to anti-biofilm formation, significantly diminishing biofilm development in a dose-dependent manner, a pivotal factor in addressing biofilm-related infections. The study also scrutinized their cytotoxicity against normal Vero and PC3 prostate cancer cells, revealing potential anticancer properties. Dose-dependent reductions in cell viability were observed for both normal and cancer cells. In conclusion, these findings underscore the versatility and promise of CSH/CSLe@MnO2NPs in diverse biomedical applications, including antibacterial, anti-biofilm, and anticancer therapies.

A compact aerosol mobility imager (AMI) for instantaneous aerosol size distribution measurements, part I: Design and model evaluation

A compact aerosol mobility imager (AMI) for instantaneous aerosol size distribution measurements, part I: Design and model evaluation

Extraction of E171 or E172 food additives from sugar-based or lipid-based complex matrices for primary particles identification by electron microscopy

Measurement of primary particle size distributions is fundamental to determining if a material should be classified as a nanomaterial according to the European Commission recommended definition. This is of particular relevance to alimentary products, where current regulation requires that any additives containing nanoforms be explicitly declared as such in the ingredients’ list. Currently, Electron Microscopy is the only instrumental technique able to reliably classify materials as nanomaterials. To verify the nanostatus of a material using this technique, it is essential to firstly extract the additives from the matrix in which they are dispersed, and then measure a wide size distribution while avoiding artefacts from the food matrix. In this operating procedure, extraction protocols, developed and applied for sugar-based or lipid-based food, are described. In particular, case studies for titanium dioxide E171 and iron oxide/iron hydroxide based materials such as E172 are considered. The protocols are based on gentle extraction of the additive materials and could, in principle, be used for other nanomaterials provided they are not soluble in water or ethanol and are resistant to enzymatic reactions. The size distribution of the extracted material can then be determined from images acquired using scanning and/or transmission electron microscopy.

The effect of different water types commonly applied during laser diffraction measurement on the particle size distribution of soils

It is expected in the future that soil particle size distribution (PSD) measurements by laser diffraction method (LDM) may replace sieve-pipette sedimentation methods (SPM) as they are faster, require less sample, and are accurate and reproducible. LDM measurement result is a continuous function of PSD, which can facilitate the conversion between the various limits (by countries, by scientific field) of the calculated particle size fractions (PSF – e.g. clay, silt, sand). Currently, there is no standard method for LDM PSD measurement. Many different types of instruments and preparation devices are currently used in laboratories, with various sample preparation, pre-treatment and measurement methods (duration, chemical and/or mechanical dispersion, settings, etc.). In soil LDM PSD measurements, researchers put relatively little emphasis on the choice of the type of aqueous media used. Thus, it is still questionable to what extent the results of the LDM measurement depend on the selection of the dispersion method and the aqueous media. For our research, eight soil samples with various physical and chemical properties were collected in Hungary. The particle size fractions (clay, silt, sand) determined with LDM (Malvern Mastersizer 3000) measured in three types of aqueous media (distilled, deionized and tap water), in different combinations of two dispersion methods (no treatment, ultrasonic or chemical dispersion with Calgon and their combination) were compared. For the comparison, PSF results of the conventional sieve pipette method (SPM) were used as a reference. Our results showed that LDM measurement can achieve various degrees of dispersion with different preparations, in many cases only partial dispersion, disaggregation, sometimes re-aggregation, and flocculation of soil particles were observed as compared to full preparation (in SPM). The “disaggregation pattern” of the soil samples also depended on the quality of the aqueous media and the properties of the soil investigated, because several types and degrees of interactions could occur in the various soil-liquid-dispersant/disaggregation effect systems.

The Árpád Mound – Geoarcheological Research of a Burial Mound in the Central Carpathian Basin

Kurgans hold exceptional archaeological, natural, and environmental historical significance in the lowland landscape of Eastern Europe, which has been extensively altered by millennia of agricultural activity. By conducting comparative soil and sedimentological analyses of the buried soil levels from kurgan construction, as well as the recent surface soil, we can uncover environmental changes from the latter half of the Holocene. These analyses also reveal how prehistoric human activities influenced local soil and environmental conditions. Our research focused on a geoarchaeological examination of a burial mound in the Hungarian Great Plain. Sedimentological analyses, including grain size distribution and magnetic susceptibility measurements, were performed on samples extracted by drilling from this mound. This comprehensive investigation enabled us to distinguish between different construction layers in the kurgan’s soil material and compare them. Additionally, it was possible to reconstruct steppe-like environmental conditions in the local surroundings of the kurgan before and during its construction.

Impaired Biofilm Development on Graphene Oxide-Metal Nanoparticle Composites.

Biofilms are one of the main threats related to bacteria. Owing to their complex structure, in which bacteria are embedded in the extracellular matrix, they are extremely challenging to eradicate, especially since they can inhabit both biotic and abiotic surfaces. This study aimed to create an effective antibiofilm nanofilm based on graphene oxide-metal nanoparticles (GOM-NPs). To create nanofilms, physicochemical analysis was performed, including zeta potential (Zp) (and the nanocomposites stability in time) and size distribution measurements, scanning transmission electron microscopy (STEM), energy dispersive X-ray analysis (EDX), and atomic force microscopy (AFM) of the nanofilm surfaces. During biological analysis, reactive oxygen species (ROS) and antioxidant capacity were measured in planktonic cells treated with the nanocomposites. Thereafter, biofilm formation was checked via crystal violet staining, biofilm thickness was assessed by confocal microscopy using double fluorescent staining, and biofilm structure was analyzed by scanning electron microscopy. The results showed that two of the three nanocomposites were effective in reducing biofilm formation (GOAg and GOZnO), although the nanofilms were characterized by the roughest surface, indicating that high surface roughness is unfavorable for biofilm formation by the tested bacterial species (Staphylococcus aureus (ATCC 25923), Salmonella enterica (ATCC 13076), Pseudomonas aeruginosa (ATCC 27853)). The performed analysis indicated that graphene oxide may be a platform for metal nanoparticles that enhances their properties (eg colloidal stability, which is maintained over time). Nanocomposites based on graphene oxide with silver nanoparticles and other types of nanocomposites with zinc oxide were effective against biofilms, contributing to changes throughout the biofilm structure, causing a significant reduction in the thickness of the structure, and affecting cell distribution. A nanocomposite consisting of graphene oxide with copper nanoparticles inhibited the biofilm, but to a lesser extent.

A novel particle size distribution correction method based on image processing and deep learning for coal quality analysis using NIRS-XRF.

The combined application of near-infrared spectroscopy (NIRS) and X-ray fluorescence spectroscopy (XRF) has achieved remarkable results in coal quality analysis by leveraging NIRS's sensitivity to organic compounds and XRF's reliability for inorganic composition. However, variations in particle size distribution negatively affect the diffuse reflectance of NIRS and the fluorescence signal intensities of XRF, leading to decreased accuracy and repeatability in predictions. To address this issue, this study innovatively proposes a particle size correction method that integrates image processing and deep learning. The method first captures micro-images of the coal sample surface using a microscope camera and employs the Segment Anything Model (SAM) for binarization to represent particle size distribution. Subsequently, a Spatial Transformer Network (STN) is applied for geometric correction, followed by feature extraction using a Convolutional Neural Network (CNN) to establish a correlation model between particle size distribution and ash measurement errors. In experiments involving 56 coal samples, including 48at 0.2mm for the standard ash prediction model and 8 within a 0∼1mm range for correction, the results showed significant improvements: standard deviation (SD), mean absolute error (MAE), and root mean square error of prediction (RMSEP) decreased from 0.321%, 0.317%, and 0.335% to 0.229%, 0.225%, and 0.257%, respectively. Using the accuracy of the 0.2mm particle size validation set as a reference, compared to before correction, the errors in these metrics were reduced by 64.06%, 50%, and 60.80%, respectively. This study demonstrates that integrating deep learning and image analysis significantly enhances the repeatability and accuracy of NIRS-XRF measurements, effectively mitigating sub-millimeter particle size effects on spectral detection results and improving model adaptability. This method, through automated particle size distribution analysis and real-time result correction, holds promise for providing essential technical support for the development of online quality detection technologies for conveyor belt materials.

Enhancing the performance and revealing the thermal behavior of the water-based coating derived from waterborne alkyd resins and totally methyl etherified amino resins

In this study, the curing parameters of the water-based coating were carefully optimized using waterborne alkyd resins as the matrix resin and totally methyl etherified amino resins as the crosslinking agent. Through an orthogonal experimental design and a controlled experiment, the optimal conditions, which were a 7:1 ratio of alkyd resins to amino resins and curing at 403.15 K for 30 min, were determined. Droplet size distribution and zeta potential measurements confirmed that the composite resin emulsion prepared with the optimal ratio was more uniformly and stably dispersed in water, which helped to optimize the coating and make it have excellent physical properties, mechanical stability and chemical durability. Thermal stability was also thoroughly evaluated by TGA analysis, paying particular attention to the third degradation stage of the optimized composite resin coating (573.15–733.15 K), pyrolysis kinetic analysis provided deeper insights into its thermal behavior. Activation energies calculated through both the KSA and Starink methods exhibited consistent values of 195.47 kJ/mol and 196.06 kJ/mol, respectively. Furthermore, a reaction mechanism function of G(α) = [−ln(1-α)]3 via C-R method implying a sigmoidal rate equation or stochastic nucleation. The activation energy calculated by this method is 211.10 kJ/mol and the pre-exponential factor is 2.22 × 1016 min−1. Notably, the thermodynamic parameters obtained from all three methods show remarkable agreement.

Electrochemical and Surface Analysis of Li10GeP2S12 Solid Electrolytes Synthesized Using a Solution-Based Method

All-solid-state batteries using flame-retardant inorganic solid electrolytes are expected to be the next-generation batteries with high safety and high output characteristics. For these, solid sulfide electrolytes with high ionic conductivity are required. Li10GeP2S12 represents a promising solid-electrolyte material for all-solid-state batteries owing to its high Li ionic conductivity (12 mS cm-1) at 27 °C [1]. To achieve practical application, Li10GeP2S12 should be synthesized using the liquid-phase method, which facilitates mass production. Our group has succeeded in a rapid synthesis of Li10GeP2S12 using excess sulfur as a solubilizer and a mixture of acetonitrile (ACN), tetrahydrofuran (THF), and a trace of ethanol (EtOH) as solvents [2]. However, Li10GeP2S12 synthesized using this approach exhibits lower ionic conductivity than that achieved using mechanical milling. In this study, Li10GeP2S12 were synthesized through the solution synthesis as the improved version. In addition, the particle characteristics of the sample synthesized by the solution synthesis were analyzed by transmission electron microscopy, particle size analysis, impedance measurements at low temperatures at 190 K, and X-ray photoelectron spectroscopy.Starting materials Li2S (Mitsuwa, 99.9 %), GeS2 (Wako, 99.9 %), P2S5 (Aldrich, 99%), and S (Aldrich, 99.8%) were mixed at a molar ratio of 5:1:1:10. The mixed powder was then added to an ACN-THF-EtOH solvent. After stirring and dissolution for 30 min, the obtained solution was vacuum-dried at 130 °C for 1 h. The precursor powder was then pelletized via uniaxial pressing. The pellet was then placed in a SiO2 tube using boats of different materials, such as quartz (SiO2), alumina (Al2O3), and titanium (Ti). Subsequently, the precursor pellet was subjected to heat treatment in a tube furnace at different temperatures (550, 650, and 750 °C) for 8 h to obtain the Li10GeP2S12 solid electrolyte powder. For comparison, this sulfite was also synthesized by mechanical milling. The crystal structure was evaluated by X-ray diffraction (XRD) measurements, the surface state was determined by X-ray photoelectron spectroscopy (XPS), and the grain size and morphology were determined by field-emission scanning electron microscopy. The ionic conductivity was also evaluated using alternating-current impedance measurements, and particle size distribution measurements and transmission electron microscopy observations were performed.The solution synthesis sample with the Ti boat exhibited an ionic conductivity of 5.5 mS cm-1, which is the highest among the extant liquid phase synthesis studies. According to the XRD patterns, impurity peaks (e.g., at SiS2) were hardly observed in the sample heat-treated in the Ti boat, and a decrease in the full-width-at-half-maximum metric was observed (Fig. 1). This result indicates that the use of a Ti boat can improve crystallinity and suppress side reactions. In comparison, the Li10GeP2S12 samples synthesized by mechanical milling exhibited ionic conductivities of 7.9 mS cm-1, higher than those achieved using solution synthesis, although the solution-synthesized sample exhibited a smaller particle size. This smaller particle size correlates with a higher grain boundary resistance, which leads to a lower total ionic conductivity. Moreover, a surface layer from the solvent was detected on the solution-synthesized particle surfaces according to XPS measurements. This surface layer contributes to a more stable interface of Li-In/Li10GeP2S12. We expect that these findings will enable the effective harnessing of particle states to develop sulfide solid electrolytes with high ionic conductivity and fine particles. Acknowledgments: This work was supported by JSPS KAKENHI (Grant Number JP 21K14716 and JP 22H04614), and the SOLiD-EV project (JPNP18003), SOLiD-NEXT project (JPNP23005) of the New Energy and Industrial Technology Development Organization (NEDO), and the GteX Program (JPMJGX23S5) of the Japan Science and Technology Agency (JST), Japan. The XPS experiments were conducted at the BL7U beamline in the Aichi Synchrotron Radiation Center, Aichi Science & Technology Foundation, Aichi, Japan (Proposal Nos. 202204118 and 202302109).

A scale-invariant log-normal droplet size distribution below the critical concentration for protein phase separation

Many proteins have been recently shown to undergo a process of phase separation that leads to the formation of biomolecular condensates. Intriguingly, it has been observed that some of these proteins form dense droplets of sizeable dimensions already below the critical concentration, which is the concentration at which phase separation occurs. To understand this phenomenon, which is not readily compatible with classical nucleation theory, we investigated the properties of the droplet size distributions as a function of protein concentration. We found that these distributions can be described by a scale-invariant log-normal function with an average that increases progressively as the concentration approaches the critical concentration from below. The results of this scaling analysis suggest the existence of a universal behaviour independent of the sequences and structures of the proteins undergoing phase separation. While we refrain from proposing a theoretical model here, we suggest that any model of protein phase separation should predict the scaling exponents that we reported here from the fitting of experimental measurements of droplet size distributions. Furthermore, based on these observations, we show that it is possible to use the scale invariance to estimate the critical concentration for protein phase separation.

Characterization of Plant based spray dried powders using oil seed proteins and chokeberry extract from wine byproduct

Spray drying is a standard method for preserving bioactive ingredients and enhancing their storage stability. This study aimed to produce entirely plant-based spray-dried powders by using hemp, canola, and flax seed proteins, combined with maltodextrin, as wall material, while chokeberry extract from wine waste served as core material. We conducted a thorough analysis of the oil-seed proteins, examining their nitrogen solubility index, emulsification, and foaming capacities. The encapsulation process was evaluated based on its yield and efficiency. The spray-dried powders were further assessed through colour analysis, particle morphology and size distribution, hygroscopicity, and storage stability measurements. The encapsulation yield with oil-seed proteins ranged from 75.0 ± 6.2 to 78.5 ± 1.3%, and the efficiency from 58.4 ± 0.8 to 77.5 ± 1.9%. These plant-based spray-dried powders exhibited similar colour parameters, morphology, and stability to those of whey protein powders. The study highlights the significant potential of oil-seed proteins in producing plant-based spray-dried powders.

Human milk fat globule size distributions: Comparison between laser diffraction and 3D confocal laser scanning microscopy

Milk fat globules (MFGs) in human milk provide energy to breastfed infants and support infant development. Accurate measurements of MFG size distributions are important to better understand MFG function and origin, as well as the influence of MFG size on milk composition analysis methods. Nevertheless, commonly used laser diffraction systems have never been thoroughly validated for size distribution measurements in human milk. Here, we introduce a new method for determining the size distribution of milk fat globules in human milk, using 3D confocal laser scanning microscopy (CLSM) in combination with fluorescent labeling of MFGs. We validate and compare 3D CLSM to laser diffraction (Mastersizer 2000, Malvern Panalytical), using polystyrene microsphere size standards. Next, we apply both methods to evaluate MFG size distributions in human milk. We show that 3D CLSM can be used to obtain more accurate size distributions between 500 nm and 10 μm compared to laser diffraction. Importantly, MFG size distributions obtained with 3D CLSM contain no secondary population around 1 μm, in contrast to laser diffraction measurements. This suggests that the bimodal MFG distribution obtained by laser diffraction can be an artifact of the built-in fitting algorithm, instead of an actual feature of human milk. This work demonstrates that care should be taken when interpreting size distributions of MFGs measured with laser diffraction and that 3D CLSM is an accurate alternative for measuring size distributions in lactation and dairy research.

Long-range transport of coarse mineral dust: an evaluation of the Met Office Unified Model against aircraft observations

Abstract. Coarse mineral dust particles have been observed much further from the Sahara than expected based on theory. They have impacts different to finer particles on Earth's radiative budget, as well as carbon and hydrological cycles, though they tend to be under-represented in climate models. We use measurements of the full dust size distribution from aircraft campaigns over the Sahara, Canaries, Cabo Verde and Caribbean. We assess the observed and modelled dust size distribution over long-range transport at high vertical resolution using the Met Office Unified Model, which represents dust up to 63.2 µm diameter, greater than most climate models. We show that the model generally replicates the vertical distribution of the total dust mass but transports larger dust particles too low in the atmosphere. Importantly, coarse particles in the model are deposited too quickly, resulting in an underestimation of dust mass that is exacerbated with westwards transport; the 20–63 µm dust mass contribution between 2 and 3.7 km altitude is underestimated by factors of up to 11 in the Sahara, 140 in the Canaries and 240 in Cabo Verde. In the Caribbean, there is negligible modelled contribution of d > 20 µm particles to total mass, compared to 10 % in the observations. This work adds to the growing body of research that demonstrates the need for a process-based evaluation of climate model dust simulations to identify where improvements could be implemented.

On the reliability of image analysis for bubble size distribution measurements in electrolyte solutions in stirred reactors

The translation of chemical processes from laboratory to industrial scale is crucial for the effective and sustainable implementation of new technologies. This transition presents significant challenges, particularly in multiphase systems where variations in physical chemistry can complicate scale-up efforts. A key aspect of this challenge is understanding bubble dynamics in gas-liquid systems, which are pivotal in processes such as hydrogen production and CO2 absorption. Bubble size significantly influences mass transfer rates and process efficiency, necessitating accurate measurement methods. A factorial design approach was employed to assess the sensitivity of results to key parameters. The findings provide quantitative guidelines for optimizing image analysis techniques and improving the accuracy of bubble size measurements in diverse operational conditions. This work advances the understanding of bubble dynamics in gas-liquid systems and offers practical insights for refining measurement techniques, ultimately supporting more effective scale-up of chemical processes.

Dependence of aerosol-borne influenza A virus infectivity on relative humidity and aerosol composition.

We describe a novel biosafety aerosol chamber equipped with state-of-the-art instrumentation for bubble-bursting aerosol generation, size distribution measurement, and condensation-growth collection to minimize sampling artifacts when measuring virus infectivity in aerosol particles. Using this facility, we investigated the effect of relative humidity (RH) in very clean air without trace gases (except ∼400 ppm CO2) on the preservation of influenza A virus (IAV) infectivity in saline aerosol particles. We characterized infectivity in terms of 99%-inactivation time, t 99, a metric we consider most relevant to airborne virus transmission. The viruses remained infectious for a long time, namely t 99 > 5 h, if RH < 30% and the particles effloresced. Under intermediate conditions of humidity (40% < RH < 70%), the loss of infectivity was the most rapid (t 99 ≈ 15-20 min, and up to t 99 ≈ 35 min at 95% RH). This is more than an order of magnitude faster than suggested by many previous studies of aerosol-borne IAV, possibly due to the use of matrices containing organic molecules, such as proteins, with protective effects for the virus. We tested this hypothesis by adding sucrose to our aerosolization medium and, indeed, observed protection of IAV at intermediate RH (55%). Interestingly, the t 99 of our measurements are also systematically lower than those in 1-μL droplet measurements of organic-free saline solutions, which cannot be explained by particle size effects alone.

Preparation of α-zein loaded with baicalincomposites: A study on their in vitro simulated digestive behavior and molecular dynamics simulation

In order to improve the bioavailability of baicalin, this article prepared for α-zein loaded with baicalin composites (α-zein@BA) by pH driven method and they were characterized using scanning electron microscopy, infrared spectroscopy, and measurement of particle size distribution in water solution phase techniques. The digestive behavior and antioxidant activity of composites before and after simulating gastrointestinal fluid in vitro were studied as well. At the same time, molecular dynamics simulation techniques were used to reveal the molecular mechanism behind the formation of the composite between the two. The results indicated that the composites of α-zein@BA were observed to be approximately spherical under a scanning electron microscope, and their particle size was mainly distributed in the range of 94.55-145.10 μm in aqueous solution, whose encapsulation efficiency of baicalin was (86.61 ± 0.71) %. Infrared spectroscopy analysis indicated that α-zein and baicalin mainly formed complexes through hydrogen bonding, electrostatic and hydrophobic interactions. The measurement results of baicalin residue in simulated digestion of gastric and intestinal fluids in vitro are as follows: α-zein@BA > Baicalin, while both significantly increased in the gastric digestion stage (P < 0.05) and significantly decreased in the intestinal digestion stage (P < 0.05). Molecular dynamics simulation studies have shown that baicalin has a promoting effect on protein structural stability, and protein 158SER and GLN196 were mainly formed hydrogen bonds with it, while hydrophobic interactions were mainly manifested between non-polar amino acids such as PHE201 and PRO200. This study indicates that α-zein and baicalin can form stable composites, improving the bioavailability of baicalin.

In situ optical measurement of particles in sediment plumes generated by a pre-prototype polymetallic nodule collector

This study presents in situ, high-resolution optical measurements of particle size distributions (PSD) within sediment plumes generated by a pre-prototype deep seabed nodule collector vehicle operating in the abyssal Pacific Ocean. These measurements were obtained using a cutting-edge instrument, the LISST-RTSSV sensor. The data collected in situ reveal marked differences compared to previously reported laboratory-based, ex situ measurements. The grain size and other key particle shape characteristics are found to be dependent on multiple factors, including the collector vehicle maneuvers, the time elapsed following sediment discharge, and the complex hydrodynamic processes that generate the sediment in suspension. Significantly, the PSD from a highly complex succession of straight-line maneuvers converges to that of the canonical case of a simple straight-line driving maneuver within a timescale of ten minutes. Our results underscore the importance of parameterizing sediment plume transport models based on well-informed, comprehensive PSDs of detrained suspended sediment measured in situ at adequate timescales and in regions no longer strongly influenced by active and complex hydrodynamic processes.