Variation Of Size Distribution Research Articles

An assessment of the durability of untreated and water repellent-treated cultural heritage stone (Döğer tuff-Turkey) by salt mist and salt crystallization tests

Salt mist and salt crystallization tests were conducted to determine the resistance of the untreated and water-repellent-treated Döğer tuff samples to salt damage. The Döğer tuffs are of volcanic origin and consist of porous pyroclastic rocks. A series of characterization studies were performed to determine the physicochemical and chemical properties (XRF), mineralogical-petrographic characteristics (polarizing optical microscopy, XRD, and SEM), and pore-size distribution (MIP) of the Döğer tuff prior to the aging tests. Following the aging experiments, the changes in weight, ultrasound pulse velocity, uniaxial compressive strength, and variations in pore size distribution were examined in the tested tuffs. In addition, SEM studies were conducted to analyze the microstructures. The untreated tuff samples were more severely affected by salt crystallization. The increases in dry weight for untreated and water-repellent-treated Döğer tuff samples were 0.27% and 0.13% after 60 cycles of salt mist exposure and 7.2% and 3.76% after salt crystallization cycles using a sodium chloride solution, respectively. Both conditions resulted from the accumulation of NaCl crystals on the tuff surface and within the pores. Salt crystal formation in a sodium sulfate solution led to dry weight change of 2.02% and 0.29% in the untreated and water-repellent-treated samples, respectively. The uniaxial compressive strength of the untreated tuff samples decreased by 36.71% in the presence of sodium chloride solution and by 72.58% in the presence of sodium sulfate solution. The ultrasound pulse velocity values decreased in all tuff samples after the salt crystallization test. However, the Döğer tuff samples were still distinguishable after both tests and their physical integrity remained intact.

Accumulation Dynamics of Defective Genomes during Experimental Evolution of Two Betacoronaviruses.

Virus-encoded replicases often generate aberrant RNA genomes, known as defective viral genomes (DVGs). When co-infected with a helper virus providing necessary proteins, DVGs can multiply and spread. While DVGs depend on the helper virus for propagation, they can in some cases disrupt infectious virus replication, impact immune responses, and affect viral persistence or evolution. Understanding the dynamics of DVGs alongside standard viral genomes during infection remains unclear. To address this, we conducted a long-term experimental evolution of two betacoronaviruses, the human coronavirus OC43 (HCoV-OC43) and the murine hepatitis virus (MHV), in cell culture at both high and low multiplicities of infection (MOI). We then performed RNA-seq at regular time intervals, reconstructed DVGs, and analyzed their accumulation dynamics. Our findings indicate that DVGs evolved to exhibit greater diversity and abundance, with deletions and insertions being the most common types. Notably, some high MOI deletions showed very limited temporary existence, while others became prevalent over time. We observed differences in DVG abundance between high and low MOI conditions in HCoV-OC43 samples. The size distribution of HCoV-OC43 genomes with deletions differed between high and low MOI passages. In low MOI lineages, short and long DVGs were the most common, with an additional cluster in high MOI lineages which became more prevalent along evolutionary time. MHV also showed variations in DVG size distribution at different MOI conditions, though they were less pronounced compared to HCoV-OC43, suggesting a more random distribution of DVG sizes. We identified hotspot regions for deletions that evolved at a high MOI, primarily within cistrons encoding structural and accessory proteins. In conclusion, our study illustrates the widespread formation of DVGs during betacoronavirus evolution, influenced by MOI and cell- and virus-specific factors.

A study about the prediction of population growth and demographic transition in Bangladesh

AbstractBangladesh is the smallest nation in South Asia, with the eighth-largest and tenth-largest population density globally. The main goal of this article is to find the population growth and demographic transition (DT) in Bangladesh. The time series data used in this paper were gathered from population surveys, national censuses, and UN Population division, population projections and estimates. There are numerous variations in the population's size and age distribution due to Bangladesh's continuing demographic transition, which creates possibilities for the economy and society and difficulties for policy. It must be successfully controlled to develop this population into stronger and more stable economic and social development. Bangladesh's population and policymakers observe increasing population growth concerns, as the country's economy and policies heavily depend on both the population's size and growth rate. Bangladesh's changing demographics are creating new economic opportunities, and the findings presented in this paper could be useful to planners and policymakers to enhance Bangladesh's population policy. At the end of the pioneering study, we presented graphically what the population of Bangladesh could be in 2000- 2100 and the impact it would have on Bangladesh.

Understanding the influence of tree size distribution on the CTL harvesting productivity of two different size harvesting machines

AbstractTree size is one of the major factors that determines harvester productivity and is heavily influenced by forest managerial activities. Stand silvicultural management can lead to managing tree size, the distribution of tree size, and tree height amongst others. Understanding the effect of tree size distribution on harvesting productivity is central for optimizing management of operations. To investigate the effects of tree size distribution on harvester productivity, productivity functions for a medium and larger-sized harvester were applied to harvester derived tree size distributions from 35 clearfelled pine stands. These functions were applied to a normal distribution of trees covering the same tree size ranges. Productivity differences were analysed on a stand-by-stand basis. Results showed that for the larger harvester, productivity rates remained constant (67.1 vs. 67.6 m3·PMH− 1) indicating relatively little sensitivity to variations in tree size distributions. Although the standard deviation (SD) halved from 11.6 to 5.6 in the case of the uniform tree distribution. The smaller harvester productivity decreased by 15% from 47.3 to 40.1 m3·PMH− 1 and the coefficient of variation (CV) by 6% in the same transition to a uniform distribution. Further investigation was done on more skewed tree size distributions, a family of nine Weibull distributions was generated, representing combinations of three mean DBH classes (25 cm, 30 cm, and 35 cm) and three levels of CV (15%, 20%, 25%), for each DBH class. Results clearly indicate that different distribution shapes have different effects on different machine sizes, and that a low CV correlates to a higher productivity in larger tree sizes. A more uniform tree size distribution also provides more predictable results (lower CV), which would promote machine scheduling and result in fewer discrepancies on production rates.

Simple retrieval of the real part of the refractive index for ambient aerosols using extinction coefficient analysis via camera and volume size distribution

This study explored a novel approach for estimating the variations in the refractive index (RI) of aerosols, which is a crucial optical parameter that contains information about particle scattering and absorption. RI is often subject to constraints related to observation time, wavelength selection, and analysis methods. To overcome these limitations, we employed real-time continuous measurements using a camera and optical particle counter (OPC) equipment and applied optimization techniques based on the Mie theory to reverse-calculate changes in the refractive index. Our methodology uses a camera to measure the aerosol extinction coefficients at three different wavelengths within the RGB spectrum (597 nm, 534 nm, and 459 nm), whereas OPC observations provide information on particle size distribution (0.127–17.58 as radius). Because the extinction efficiency at known wavelengths varies with the refractive index according to the Mie theory, we retrieved the refractive index, which is an unknown variable, from the extinction coefficient equation. We focused on the real part of the RI because it is challenging to discern the imaginary part of the RI from the visible wavelengths. Our observations were conducted in areas near Busan Harbor and in mixed residential regions. The real part of the RI was determined to be 1.53±0.12. During periods of observed dust events, the refractive index's real part was 1.62±0.05, while during periods anticipated to have emissions of fine aerosols, it was 1.51±0.10. The retrieved RI fell within a range similar to that in other studies, and the changes in the refractive index showed meaningful patterns when analyzed for variations in the particle size distribution and changes in the scattering coefficient. This approach has the potential to advance our understanding of aerosol optical properties and can be applied to real-time analyses with a relatively simple equipment setup, thereby opening new possibilities for its use as a critical variable in optical measurements and environmental models.

Significant changes in the physicochemical properties of BC-containing particles during the cold season in Beijing

The ambient air quality has improved significantly under strict emission controls in Beijing, China over the last decade. Black carbon (BC), as a short-lived climate forcer in ambient aerosols, profoundly impacts the air quality and climate. Previous studies have demonstrated a decline in the mass concentration of BC. In this study, we characterized the chemical compositions and size distributions of BC-containing particles during the cold season of 2022 in Beijing using state-of-the-art instruments capable of exclusively measuring BC-containing particles. The optical properties of BC-containing particles were further calculated based on the Mie theory. Moreover, we compared the properties of BC-containing particles in 2022 with the results of previous studies. The results showed that the diameters of BC cores became larger while the coating thickness of BC-containing particles became thinner in 2022. For the coating materials, the mass fraction of nitrate increased obviously, and even replaced organic matter as the dominant component during the peak of the pollution period. Variations in chemical compositions and size distributions resulted in lower mass absorption cross-sections (MAC) of BC-containing particles from 10.5 ± 1.1 m2/g in 2016 to 7.3 ± 0.8 m2/g in 2022, reduced by 30.5%. Our results demonstrate the synergistic benefits of air pollution control in improving air quality and mitigating climate change. Therefore, the MAC of BC adopted in climate models should vary with the changing air pollution levels. This study emphasizes that it is imperative to conduct long-term observations of BC-containing particles to better estimate BC's climate effects.

Comparison of Characteristics and Antimicrobial Activity of Synthesized Zinc Oxide And Magnetite Iron Oxide Nanoparticles Using Four Different Plant Extracts

The aim of this study was to synthesize Zinc oxide (ZnO) and magnetite ıron oxide (Fe3O4) nanoparticles utilizing a precipitation method, employing plant extracts from Ocimum basilica(1), Cinnamomum zeylanicum(2), Lactarius salmonicolor(3) and Paeonia kesrouanensis(4) as reduction and stabilizing agents. Additionally, the antimicrobial activity of these nanoparticles against both gram-positive (S. aureus, ATCC 25923) and gram-negative (E. coli, ATCC 25922; P. aeroginosa, PAO1), bacteria as well as fungus (C. albicans 90028) was evaluated. The nanoparticles (NPs) were characterised by various analyses, including TEM, SEM, XRD, FTIR, DSL, and zeta potential. Based on the TEM image, the ZnONPs exhibited a cluster of flower-like structures, whereas the Fe3O4NPs displayed a spherical shape with a varying size distribution. The zeta potential values for ZnO NPs ranged from -5.35 to -16.9, while for Fe3O4NPs ranged from -7.43 to -20.7. All ZnO nanoparticles exhibited antimicrobial activity exclusively against the S. aureus strain, whereas Fe3O4NPs did not demonstrate any antibacterial effect.

Comprehensive effects of microplastics on algae-laden surface water treatment by coagulation-ultrafiltration combined process: Algae cultivation, coagulation performance and membrane fouling development

In coastal areas, the surface water has been simultaneously exposed to the algae blooms caused by eutrophication and the microplastics (MPs) pollution originating from active human activities. As a practical alternative to address these issues in drinking water plant, coagulation-ultrafiltration combined process is still confronted with the limited understanding about the comprehensive effects of MPs on algae-laden surface water (ASW) treatment. Considering the migration of MPs in nature environment and drinking water treatment process, this study first aims to systematically investigate the influence of MPs on algae cultivation, coagulation performance and membrane fouling development. The results of algae cultivation indicate that MPs stimulated the algae activity by 58 % and then constantly suppressed the secretion of protein-like, humic-like and polysaccharide-like metabolites. The variation of particle size distribution and zeta potential confirm that MPs acted as nuclei to facilitate the development of large coagulation flocs with an increasing average size from 82.6 μm to 107.6 μm, during which the negatively charged pollutants were neutralized and removed from ASW. According to the SEM images, MPs could destroy the structure of fouling layer on 50 kDa membranes during the filtration of ASW coagulation effluent. Its synergistic effect with the enhanced coagulation performance and the suppressed EOM secretion contributed to the alleviation of membrane fouling caused by overlapped large-sized foulants. However, the interaction between the enriched organic foulants by MPs and the deposited coagulants on 300 kDa membranes facilitated the development of cake layer, leading to the deterioration of membrane permeability. This study emphasizes the importance in concerning the existence of MPs during the treatment of ASW by coagulation-ultrafiltration combined process and their exact influence in water purification efficiency.

Sediment sorting and transport mechanism controlled by both soil properties and hydraulic parameters on hillslopes

Understanding the sediment sorting and transport processes is is crucial for enhancing the understanding of soil erosion mechanisms and improving soil erosion prediction. However, quantitative studies based on the coupling effects of both hydraulic parameters and soil properties are still lacking. In this study, five loessial soils with varying physicochemical properties were collected in the Loess Plateau of China, and simulated rainfall experiments were carried out in a metal box with a slope of 20 degrees under rainfall intensities of 1, 1.5, and 2 mm min−1. Runoff samples were collected to analyze the variation in erosion rates and effective particle size distribution of eroded sediments during the rainfall process. The results showed that the stream power was the optimal parameter to model the erosion rate, and a power function incorporating the clay content and stream power could well predict the erosion rate of different soils. The enrichment ratio indicated the enrichment of fine particles and depletion of coarse particles. And the sediment sorting degree increased with increasing soil clay content. The critical particle size for distinguishing different transport mechanisms varied among soils, with more than 55.46 % of the total sediment transported by suspension/saltation. A linear function and power function including the original soil particle size distribution and stream power were developed to quantify the sediment clay content and the relative contribution of different transport mechanisms. This study could be helpful to improve the soil erosion prediction model and provide basic guidelines for regional soil and water conservation.

Effect of dust size distribution and nonadiabatic charge variation on dispersion relation for linear waves in inhomogeneous complex plasmas

This paper explores linear waves’ instability in nonuniform complex plasmas with dust size distribution and non-adiabatic dust charge fluctuation. For this purpose, the dispersion relation is obtained with the aid of linearizing the hydrodynamic equations governing the properties of linear waves. The contribution of physical parameters such as inhomogeneity, nonadiabatic dust charge fluctuation, and dust size distribution to the features of dust acoustic waves is examined at great length. The numerical results show that the present research results are very important in the phenomenon of space astrophysical and experimental plasmas.

Rheology and yield stress evolution of highly flowable cementitious grouting materials: Mechanisms and modeling

To study the rheological properties of grouting materials, the effects of sand-binder ratio, water-binder ratio, and rest time on the rheological model and parameters were studied through rheological tests. Through the cryo-scanning electron microscopy test to observe the structural build-up process of microstructures with rest time, the particle size test to measure the size distribution variation of flocculated structures over rest time, and the low-field nuclear magnetic resonance test to measure the change of water content in the slurry, the evolution mechanism of yield stress was studied. The results showed that the rheological model was consistent with Herschel–Bulkley model (H–B model). The yield stress increased with time. The growth of network flocculated structures and the decrease in the lubrication effect of water caused an increase in the aggregate particles–cement paste interaction stress. Therefore, the yield stress of the grouting materials increased over time. Considering the combined influences of the flocculation effect, hydration reaction, and the aggregate particles–cement paste interaction, a new evolution model was proposed to better describe the evolution law of yield stress with time. The results could provide a basis for the study on flow diffusion of grouting materials and an in-depth understanding of the time-dependent rheological properties of cement-based materials containing aggregate particles.

A Three-Wavelength Optical Sensor for Measuring the Multi-Particle-Size Channel Mass Concentration of Thermal Power Plant Emissions.

Emissions from thermal power plants have always been the central consideration for environmental protection. Existing optical sensors in thermal power plants usually measure the total mass concentration of the particulate matter (PM) by a single-wavelength laser, bearing intrinsic errors owing to the variation in particle size distribution (PSD). However, the total mass concentration alone cannot characterize all the harmful effects of the air pollution caused by the power plant. Therefore, it is necessary to measure the mass concentration and PSD simultaneously, based on which we can obtain multi-particle-size channel mass concentration. To achieve this, we designed an optical sensor based on the three-wavelength technique and tested its performance in a practical environment. Results showed that the prototype cannot only correctly measure the mass concentration of the emitted PM but also determine the mean diameter and standard deviation of the PSDs. Hence, the mass concentrations of PM10, PM2.5, and PM1 are calculated, and the air pollutants emission by a thermal power plant can be estimated comprehensively.

Forecasting Sauter mean droplet size and examining the range of droplet sizes in a Tenova liquid–liquid extraction column

A new type of Tenova pulsed extraction column was introduced in 2017. It is the newest generation of pulsed columns. Due to the internal equipment of this column and the lack of moving parts and the simplicity and speed of repairs and maintenance, it has been the focus of researchers in recent years. No correlations for predicting the mean drop size and drop size distribution of the Tenova column have been reported. The Sauter mean drop diameter and drop size distribution are investigated for a Tenova pulsed column with a diameter and an active height of 7.4 and 73 cm, respectively. Three standard chemical systems of isobutyl acetate-water, isobutanol-water, and toluene-water have been used. The effects of pulse intensity, dispersed and continuous phase flow rates have been taken into account. In each experiment, 200–300 drops have been analyzed in a total of 10,000 drops. The investigation covered a spectrum of physical properties, notably surface tension (within a range of 1.75–36 mN/m). Operating conditions including pulse intensity (in the range of 0.2–2 cm/s) and the flow rate of continuous and dispersed phases (in the range of 8–30 L/h) have been investigated. Methods based on artificial intelligence (AI) such as multilayer perceptron neural networks and gene expression programming were combined with a dimensional analysis approach to provide a new approach to estimating the mean drop diameter (d32). Experimental results have been compared with the equations found by other researchers in similar columns. The variation of drop size distribution has also been experimentally obtained.Methods based on artificial intelligence (AI) such as multilayer perceptron neural networks and gene expression programming were combined with a dimensional analysis approach to provide a new approach to estimating the mean drop diameter (d32). Experimental results have been compared with the equations found by other researchers in similar columns. The variation of drop size distribution has also been experimentally obtained.

Numerical and Experimental Investigation for Application of CoNiCrAlY Coatings by HVAF

AbstractA relatively small change in oxide content and microstructure in MCrAlY coatings (M = Co, Ni) can affect the functionality of the coating for oxidation protection or as a bond coat. The objective of this study is to fabricate a CoNiCrAlY coating with low porosity and low oxide content. The high velocity air-fuel (HVAF) process, with its relatively low process temperature, is particularly suitable for the deposition of spray materials that are susceptible to oxidation or degradation at high temperature. A CFD simulation model of HVAF process is developed to determine the process parameters for fabricating CoNiCrAlY coating. The simulation results are validated by particle diagnostics, thereby establishing a comprehensive understanding of the underlying process. To assess the coating microstructure, XRD and EDS analyses as well as observation of cross sections of the coatings are conducted. The results highlight the influence of various factors, such as the variation of carrier gas and particle size distribution, on the quality of the coatings. Consequently, the utilization of simulation-based process parameter development is well supported by the coating fabrications, offering valuable insights into the processes prior to implementation.

Improved multivariable algorithms for estimating oceanic particulate organic carbon concentration from optical backscattering and chlorophyll-a measurements

The capability to estimate the oceanic particulate organic carbon concentration (POC) from optical measurements is crucial for assessing the dynamics of this carbon reservoir and the capacity of the biological pump to sequester atmospheric carbon dioxide in the deep ocean. Optical approaches are routinely used to estimate oceanic POC from the spectral particulate backscattering coefficient bbp, either directly (e.g., with backscattering sensors on underwater platforms like BGC-Argo floats) or indirectly (e.g., with satellite remote sensing). However, the reliability of algorithms which relate POC to bbp is typically limited due to the complexity of interactions between light and natural assemblages of marine particles, which depend on variations in particle concentration, composition, and size distribution. This study expands on our previous work by analysis of an extended field dataset created with judicious data inclusion criteria with the aim to provide POC algorithms for multiple light wavelengths of measured bbp, which can be useful for applications with in situ optical sensors as well as above-water active or passive measurement systems. We describe an improved empirical multivariable approach to estimate POC from simultaneous measurements of bbp and chlorophyll-a concentration (Chla) to better account for the effects of variable particle composition on the relationship between POC and bbp. The multivariable regression models are formulated using a relatively large dataset of coincident measurements of POC, bbp, and Chla, including surface and subsurface data from the Atlantic, Pacific, Arctic, and Southern Oceans. We show that the multivariable algorithm provides reduced uncertainty of estimated POC across diverse marine environments when compared with a traditional univariate algorithm based on only bbp. We also propose an improved formulation of univariate algorithm based on bbp alone. Finally, we examine performance of several algorithms to estimate POC using our dataset as well as a dataset consisting of optical measurements from BGC-Argo floats and traditional POC measurements collected during a coincident research cruise in the Atlantic Ocean.

The Characterization of Residues Related to the Roasting– Leaching–Electrowinning Zinc Production Route for Further Metal Extraction

Super-hot acid leach residue is generated during zinc production in the roasting–leaching–electrowinning route, where both primary and secondary resources are used as feed material. This residue may contain valuable metals, such as lead, zinc, and iron, as well as precious metals, such as gold and silver. Four materials, namely super-hot acid leach residue, a residue formed when super-hot acid leach residue is selectively leached for lead with triethylenetetramine, as well as flotation concentrate, and flotation tailings formed in a selective silver flotation process with super-hot acid leach residue as the feed material were characterized to obtain a deeper understanding of possible further metal extraction. These four materials were characterized for chemical composition, mineralogy, and mineral distribution via chemical analyses, X-ray diffraction, and energy-dispersive scanning electron microscopy, respectively. The scanning electron microscope images showed that the materials have large variations in particle size distribution and composition. The results showed that the main lead phase in super-hot acid leach residue is lead sulfate, whereas it is mostly converted to lead sulfide during the selective lead leaching of the super-hot acid leach residue. The remaining lead sulfate is found in a solid solution with barium sulfate. Extracting lead from super-hot acid leach residue via triethylenetetramine leaching resulted in increased concentrations of gold and silver by 41% and 42%, respectively. The identified silver phases in super-hot acid leach residue may correspond to silver sulfide, silver chloride, and elementary silver, where silver sulfide was the most commonly occurring silver phase. After leaching this selectively for lead with triethylenetetramine, similar silver phases were identified, but silver sulfide and silver chloride occurred to a similar extent. Additionally, silver copper sulfide was detected. The presence of different silver phases might pose a challenge to reaching high silver recovery during leaching as the optimum leaching conditions differ somewhat. Furthermore, elemental sulfur, with a tendency to coat gold and silver particle surfaces, which is indicated to be present in all materials except the silver flotation tailings, may hinder metal extraction.

Numerical Simulation of the Effect of Particle Size Distribution on Fluidized Bed Gasifier

The rapid development of technology and industrialization has confronted humanity with two important problems: the depletion of fossil energy resources and environmental damage. This study aims to determine the effect of the particle size distribution of the bed on the composition of the produced syngas which has the potential to replace fossil fuels. The particle bed used is silica sand with 4 variations of particle size distribution with a diameter of 600-1000 µm. The results of this study indicate that the larger the particle size distribution of the bed can reduce the temperature distribution and composition of the syngas produced. The highest temperature distribution was found in the 1st particle size distribution variation of 1060.23 K. The highest syngas composition was found in the 3rd particle size distribution variation of 2.21% CH4, 19.68% CO, 6.21% CO2, and 18.51% H2The highest syngas composition was found in the 3rd particle size distribution variation of 2.21% CH4, 19.68% CO, 6.21% CO2, and 18.51% H2. The lowest temperature distribution was obtained in the 3rd particle size distribution variation of 1057.77 K. The lowest syngas composition was found in the 4th particle size distribution 1.99% CH4, 17.71% CO, 5.63% CO2, and 16.66% H2.

In situ measurements of perturbations to stratospheric aerosol and modeled ozone and radiative impacts following the 2021 La Soufrière eruption

Abstract. Stratospheric aerosols play important roles in Earth's radiative budget and in heterogeneous chemistry. Volcanic eruptions modulate the stratospheric aerosol layer by injecting particles and particle precursors like sulfur dioxide (SO2) into the stratosphere. Beginning on 9 April 2021, La Soufrière erupted, injecting SO2 into the tropical upper troposphere and lower stratosphere, yielding a peak SO2 loading of 0.3–0.4 Tg. The resulting volcanic aerosol plumes dispersed predominately over the Northern Hemisphere (NH), as indicated by the CALIOP/CALIPSO satellite observations and model simulations. From June to August 2021 and May to July 2022, the NASA ER-2 high-altitude aircraft extensively sampled the stratospheric aerosol layer over the continental United States during the Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) mission. These in situ aerosol measurements provide detailed insights into the number concentration, size distribution, and spatiotemporal variations of particles within volcanic plumes. Notably, aerosol surface area density and number density in 2021 were enhanced by a factor of 2–4 between 380–500 K potential temperature compared to the 2022 DCOTSS observations, which were minimally influenced by volcanic activity. Within the volcanic plume, the observed aerosol number density exhibited significant meridional and zonal variations, while the mode and shape of aerosol size distributions did not vary. The La Soufrière eruption led to an increase in the number concentration of small particles (<400 nm), resulting in a smaller aerosol effective diameter during the summer of 2021 compared to the baseline conditions in the summer of 2022, as observed in regular ER-2 profiles over Salina, Kansas. A similar reduction in aerosol effective diameter was not observed in ER-2 profiles over Palmdale, California, possibly due to the values that were already smaller in that region during the limited sampling period in 2022. Additionally, we modeled the eruption with the SOCOL-AERv2 aerosol–chemistry–climate model. The modeled aerosol enhancement aligned well with DCOTSS observations, although the direct comparison was complicated by issues related to the model's background aerosol burden. This study indicates that the La Soufrière eruption contributed approximately 0.6 % to Arctic and Antarctic ozone column depletion in both 2021 and 2022, which is well within the range of natural variability. The modeled top-of-atmosphere 1-year global average radiative forcing was −0.08 W m−2 clear-sky and −0.04 W m−2 all-sky. The radiative effects were concentrated in the tropics and NH midlatitudes and diminished to near-baseline levels after 1 year.

Effects of secondary breakup, collision dynamics, gravity and evaporation on droplet size distribution in a pressure-swirl JET A-1 spray

Size and velocity of droplets in pressure-swirl sprays vary with distance downstream the nozzle. This study aims to explain the phenomena contributing to size-resolved spatial variation of the drop size distribution for Jet A-1 spray from a small pressure swirl atomizer injected into quiescent ambient air at atmospheric conditions. The effects of secondary breakup, droplet collisions, gravity, drag-driven spray dispersion, and evaporation are evaluated. Phase Doppler anemometer (PDA) was used to resolve the velocity and size of the droplets in radial profiles at several axial distances (Z) from the nozzle exit at injection pressures between 0.5 and 1.5 MPa. The droplet motion and collision dynamics were qualitatively characterised by high-speed imaging. The analysis focused on areas along 1) the spray axis and 2) the liquid sheet direction. The first area covers small droplets with marginal evolution, while the mean drop size in the second area significantly increases downstream. The local drop size distribution and its axial evolution results from a combined effect of ballistic filtering (drifting of small droplets from periphery to spray centre and large droplets vice versa), centrifugal and turbulent droplet dispersion, and droplet collisions (increasing drop size with distance). The relative droplet-gas velocity was found at investigated Z positions too small for drag-driven secondary droplet breakup to occur. Evaporation of Jet A-1 sprayed at room temperature and pressure into still atmosphere reduces the drop size marginally. Trajectory of all drop sizes is insignificantly altered by gravity. The smallest droplets are strongly drag-driven to the spray axis, while large ones disperse centrifugally and have sufficient momentum to neglect the gravity. Combining results from imaging and laser diagnostics, various collision outcomes were identified, with a conclusion that these depend on the size and velocity of colliding droplets. Coalescing collisions dominate and strongly increase the mean drop size downstream the spray at off-axis positions while insignificantly contribute along the spray axis. The drop size span factor reduces with Z as separative collisions between large droplets and mixed-type collisions between small and large droplets narrow the drop size distribution. The above effects can be most easily amplified for drop size reduction via modification of physical properties of sprayed liquid by its heating.

Cisco population characteristics in Wisconsin lakes in relation to lake‐ and landscape‐level factors

AbstractObjectiveDeclines in Cisco Coregonus artedi populations in some inland lakes have prompted assessments of Cisco occurrence and extirpation risk in relation to various stressors to identify refuge lakes and factors that promote Cisco persistence. However, most previous assessments have focused on presence–absence of Cisco rather than examining how population characteristics, such as relative abundance or growth, might change in relation to lake‐ and landscape‐level environmental factors. Consequently, our specific objectives were to identify important environmental factors explaining variation in Cisco relative abundance and growth and to determine whether population metrics describing size and age distributions were related to relative abundance in Wisconsin inland lakes.MethodsCisco were collected from 48 inland Wisconsin lakes during 2011–2015 using vertical monofilament gill nets and population‐specific relative abundance estimates (catch per unit effort [CPUE]) were quantified as the number of individuals per gill‐net night. Sagittal otoliths were removed from a subsample of Cisco for age estimation and growth was indexed as mean total length (TL; mm) at age 2. Length and age data were used to develop a suite of metrics describing size and age distributions of each population. Random forest models were used to evaluate relationships between 10 biologically relevant predictor variables representing variation in physical, climatic, catchment, and limnological characteristics and Cisco CPUE and growth. Pearson correlations were used to determine whether population characteristics were related to CPUE.ResultCisco populations exhibited large variation in relative abundance, growth, and size and age distributions. Best‐fit random forest models explained approximately 25% of the variation in Cisco CPUE and 46% of the variation in growth. Growing degree‐days and variables associated with availability, quality, and quantity of suitable oxythermal conditions were identified as important predictors of both Cisco CPUE and growth; CPUE was also identified as an important predictor of growth. Mean TL and mean TL at age 2 were negatively related to Cisco CPUE, whereas mean age, number of age‐classes present, and maximum observed age were positively related to CPUE.ConclusionOur results suggest that maintenance of suitable oxythermal habitat conditions may be critical to conserving abundant Cisco populations. Our assessment also provides insights on how Cisco populations may respond to environmental and anthropogenic stressors, which could aid ongoing and future conservation and management efforts in Wisconsin and elsewhere.