Range Of Size Distribution Research Articles

Portable X-ray fluorescence for autonomous in-situ characterization of chloride in oil and gas waste

Soil salinization resulting from anthropogenic activities affects soil health and productivity. Methods that can provide rapid, inexpensive, and accurate salinity characterization over vast areas of soil and waste materials will help in managing their impacts. The objective of this work was to evaluate the accuracy and precision of portable X-ray Fluorescence (pXRF) Cl− measurements of highly saline waste material (WMs) from oil and gas production sites. We compared pXRF Cl− measurements of three unconsolidated WMs to a standard laboratory method for determining soil salinity and identified the WM properties that most affect the precision and accuracy of the pXRF Cl− measurement. Despite covering a range of several orders of magnitude in chloride concentration, calibrated pXRF measurements varied by no more than 14% compared to standard laboratory Cl− measurements for dry homogenous samples. Measurements taken of WMs that were not homogenized decreased pXRF accuracy by 75% while moisture content decreased accuracy by 15%. Field measurements made at different areas inside an oil and gas WM pit were accurate within 60% of the standard laboratory Cl− measurements, despite the samples having a wide range of moisture content and particle size distributions. This study indicates that pXRF can be used to rapidly characterize soil salinity in-situ with acceptable accuracy and precision for screening purposes, opening the door for automated robotic measurements of chloride over large areas.

Behavioral plasticity mediates adaptation to changes in food provisioning following the COVID-19 lockdown in black-headed gulls (Larus ridibundus)

The 2020 COVID-19 lockdown provides an opportunity to assess how the anthropause affected the behavior of birds. Black-headed gulls (Larus ridibundus) wintering at Dianchi Lake (Yunnan Province, southwestern China) prefer to forage on easily accessible human-provided food at various sites along the lake. Following the closure of the lake because of the pandemic, synthetic food was provided at a single location. We expected that the home range size and distribution of gulls would change in response to these changes in food provisioning. A total of 91 gulls were tagged with satellite transmitters in November 2018 and March 2019, and their movements were tracked during the winter months. We analyzed their home range size and spatial distribution in four periods, SCP2019, SOP2019, SCP2020, and SOP2020 (Scenic Opening/Closing Period in 2019/2020), and the difference between SOP2019 and SCP2019 was used as the control group. The eutrophication level in the wintering periods “Nov. 2018–Apr. 2019” and “Oct. 2019–Apr. 2020” was determined using the Normalized Difference Vegetation Index (NDVI), and the coverage ratio of algal blooms and NDVI were used as indicators of the amount of naturally available food. The home range sizes of gulls were reduced in SCP2020 compared with SOP2019, SCP2019, and SOP2020. The gulls were most abundant in the 600–900 m buffer zone and least abundant in the 0–300 m buffer zone in SCP2019; they were most abundant in the 0–300 m buffer zone and least abundant in the 900–2000 m buffer zone in SCP2020. These patterns were consistent with variation in the NDVI and the coverage ratio of algal blooms among buffer zones. Changes in wintering behaviors in SCP2020 relative to other periods suggested that gulls modified their behavior following anthropause-related changes in the distribution and provisioning of food. Our findings provide insights into the role of behavioral plasticity in mediating adaptation to changes in human activities in birds.

A nanoparticle formation model considering layered motion based on an electrical explosion experiment with Al wires

To study the evolution of nanoparticles during Al wire electrical explosion, a nanoparticle formation model that considered layered motion was developed, and an experimental system was set up to carry out electrical explosion experiments using 0.1 mm and 0.2 mm Al wires. The characteristic parameters and evolution process during the formation of nanoparticles were calculated and analyzed. The results show that the maximum velocities of the innermost and outermost layers are about 1200 m·s−1 and 1600 m·s−1, and the velocity of the middle layer is about 1400 m·s−1, respectively. Most of the nanoparticles are formed in the temperature range of 2600 K‒2500 K. The characteristic temperature for the formation of Al nanoparticles is ∼2520 K, which is also the characteristic temperature of other parameters. The size distribution range of the formed nanoparticles is 18 to 110 nm, and most of them are around 22 nm. The variation of saturated vapor pressure determines the temperature distribution range of particle nucleation. There is a minimum critical diameter of particles (∼25 nm); particles smaller than the critical diameter can grow into larger particles during surface growth. Particle motion has an effect on the surface growth and aggregation process of particles, and also on the distribution area of larger-diameter particles. The simulation results are in good agreement with the experiments. We provide a method to estimate the size and distribution of nanoparticles, which is of great significance to understand the formation process of particles during the evolution of wire electrical explosion.

Quantitative characterization and formation mechanism of the pore system heterogeneity: Examples from organic-rich laminated and organic-poor layered shales of the upper triassic chang 7 member in the southern Ordos Basin, China

The heterogeneity of shale pore structure is a vital problem that cannot be ignored in the process of shale oil exploration and development. The organic-rich laminated shale (ORLS) and organic-poor layered shale (OPLS) show significantly different pore system heterogeneity. In this study area, the porosity and permeability of ORLS (2.7% and 0.00053mD) are higher than those of OPLS (2.29% and 0.00041mD). The heterogeneity of the pore system in ORLS is reflected by the wider pore size range of intercrystalline pores (pore size of 0.002–5.5 μm), the stronger holistic distribution heterogeneity of intergranular pores (average △α of 1.61) and organic pores (average △f of 2.65) at local locations. The wider range and discontinuity of the pore size distribution for intergranular pores and organic pores, and the instability of the morphological structure for intercrystalline pores and microfractures, all lead to the heterogeneity of the pore system in OPLS. The micropore (<2 nm) volume and macropore (>50 nm) volume of ORLS are higher than that of OPLS, while the surface area and volume of mesopores (2–50 nm) are lower than those of OPLS. The macropore has the most obvious fractal characteristics and three fractal dimensions. The macropore volume of ORLS is positively correlated with reservoir physical and pore multifractal properties, while the mesopore volume of OPLS is positively correlated with reservoir properties and negatively correlated with fractal properties. Pore system evolution patterns of shale reservoirs are obviously controlled by the mineral composition, laminae, TOC content, thermal evolution degree and fluid pathways. The macropore volume in ORLS shows a clear positive correlation with the pyrite content. The high TOC content and high thermal evolution degree are more likely to produce erosive fluids. Laminar interfaces, microfractures and primary pores provide channels for the fluid migration. The development degree of secondary dissolution may be an important factor leading to the difference of reservoir qualities between ORLS and OPLS.

Treatment of wastewater from the flocculation process of waste cutting fluid by zerovalent iron catalyst

Waste cutting fluids are considered as hazardous wastes because they contain numerous different components causing environmental problems. Normally, a flocculation method is applied to treat preliminarily. However, the output wastewater still needs treating further to meet the national standards of industrial wastewater before disposal. So, this research reports the secondary treatment stage of the waste cutting fluid collected from an industrial factory in Vietnam using zero valent iron (ZVI) catalyst. This catalyst was synthesized via a redox reaction between sodium borohydride (NaBH4) and ferric chloride (FeCl3). Key factors affecting the quality of the ZVI particles such as the concentration of the NaBH4 reductant, reaction temperature, and dropping rate were investigated systematically. At the optimum synthesis conditions, viz. the NaBH4 concentration of 0.2 M, reaction temperature of 25 oC and the dropping rate of 3 ml/min, the synthesized ZVI exhibited a narrow range of particle size distribution with a mean size of 3.9 μm, followed by a high surface area, and good catalytic activity. As a catalyst for secondary treatment of the waste cutting fluid, the synthesized ZVI demonstrated a moderate chemical oxygen demand (COD) removal performance of 49%, corresponding to COD reduction for from 4023 mg/l to about 2059 mg/l.

Seed traits and phylogeny explain plants' geographic distribution

Abstract. Understanding the mechanisms that shape the geographic distribution of plant species is a central theme of biogeography. Although seed mass, seed dispersal mode and phylogeny have long been suspected to affect species distribution, the link between the sources of variation in these attributes and their effects on the distribution of seed plants are poorly documented. This study aims to quantify the joint effects of key seed traits and phylogeny on species distribution. We collected the seed mass and seed dispersal mode from 1426 species of seed plants representing 501 genera of 122 families and used 4 138 851 specimens to model species distributional range size. Phylogenetic generalized least-squares regression and variation partitioning were performed to estimate the effects of seed mass, seed dispersal mode and phylogeny on species distribution. We found that species distributional range size was significantly constrained by phylogeny. Seed mass and its intraspecific variation were also important in limiting species distribution, but their effects were different among species with different dispersal modes. Variation partitioning revealed that seed mass, seed mass variability, seed dispersal mode and phylogeny together explained 46.82 % of the variance in species range size. Although seed traits are not typically used to model the geographic distributions of seed plants, our study provides direct evidence showing seed mass, seed dispersal mode and phylogeny are important in explaining species geographic distribution. This finding underscores the necessity to include seed traits and the phylogenetic history of species in climate-based niche models for predicting the response of plant geographic distribution to climate change.

Predicting Fuel Cell Ink Aggregation

Polymer-electrolyte fuel cells (PEFCs) provide multisector decarbonization solutions including in transportation, manufacturing, and long-term energy storage. They have become increasingly popular in these areas due to their high efficiency, power density, and low (or zero) emissions compared to traditional fossil-fuel dependent processes. The PEFC catalyst layer is the most complex and key part of the cell, and is critical for optimizing PEFC performance. Several studies have explored the structure/function relationships of PEFC catalyst layers, yet the physics and interactions controlling its in-situ formation remain a mystery. PEFC catalyst layers are traditionally fabricated out of a catalyst supported on a carbon nanoparticle with an ionomer, traditionally perfluorosulfonic acids (PFSAs) such as Nafion, as a binder, which stabilizes the carbon suspensions in the ink dispersion. Recent studies demonstrated the importance of pH as an experimental parameter for both comparison and characterization of such systems.1 In this talk, we explore the interactions in the colloidal inks through detailed mathematical modeling. We propose a kinetics-based model representing species aggregation with pointwise interacting spheres that vary in charge through buried side chains for predicting the aggregation behavior of Nafion and carbon in solutions under varying conditions, such as solvent, Nafion wt% and carbon wt%. To demonstrate the accuracy and robustness of the model, we compare the results against a range of pH conditions and size distributions. The insights from the model help establish design criteria and guide future ink and process conditions.AcknowledgementsThis study was conducted under the Million Miles Fuel Cell Truck Consortium (M2FCT) funded by the Hydrogen and Fuel Cell Technologies Office in the Energy Efficiency and Renewable Energy Office of the U.S. Department of Energy under contract DE-AC02-05CH11231.References S. A. Berlinger, B. D. McCloskey, and A. Z. Weber, J. Phys. Chem. B, 122, 7790–7796 (2018).

A Comparative Study on the Structural Properties and Lipid Profile of Mushroom (Pleurotus ostreatus) Powder Obtained by Different Drying Methods

Mushroom powders, as functional food ingredients, have attracted much attention in recent years. In the present study, four drying methods, i.e., freeze drying (FD), hot air drying (HAD), microwave drying (MWD), and sun drying (SD), were investigated to determine the effects on the structure and lipid profile of mushroom powder. The morphology of the mushroom powder was studied by using X-ray microtomography. The surface of the particles was studied by using scanning electron microscopy. The identification of lipophilic components was carried out by using gas chromatography in a powder extract obtained under in vitro conditions simulating digestion. The FD powder extract, with the widest range of particle size distribution (17.7–2270.3 µm), represented flake shapes with a porous structure. In addition, particles with minimal sizes (17.7–35.4 µm) were recorded only in the FD powder extract. Among the samples, the representation of large granules (1135.5–2270.3 µm) was ranked in the order: MWD &lt; SD &lt; FD &lt; HAD, where the MWD sample was characterized by a narrow particle size composition (35.4–1135.1 µm), whereas the HAD granules were characerizedd by a lamellar structure with multiple deformations. The MWD particles were fused microaglomerates, whereas the SD powder consisted of amorphous particles with a strongly wrinkled surface. Sixty compounds were identified in the lipophilic powder extracts. Regarding the number of compounds identified, the powder extracts were ranked in the order MWD &gt; FD &gt; HAD &gt; SD. Based on the content of linoleic acid, the samples were ranked in the order HAD &lt; MWD &lt; FD &lt; SD, and, based on the stearic acid concentration, they were ranked in the order FD &lt; HAD &lt; MWD &lt; SD. Oleic acid was identified in the HAD and MWD powder extracts, and palmitic acid was only identified in the SD powder extract. According to the number of fatty acid esters, the extracts were ranked in the order SD &lt; FD &lt; MWD &lt; HAD. As per the concentration, alkanes were obtained from HAD and MWD samples and fatty alcohols were obtained from the FD samples. Lipophilic substances with a possible undesirable effect were identified only in the FD and HAD powder extracts. The results of this study expand the currently limited knowledge about the effect of various drying methods on the structural properties of mushroom (Pleurotus ostreatus) powder and its lipophilic component. The new information obtained will contribute to better management of mushroom raw materials in terms of optimization, taking into consideration the manufacturer’s interest in the technological and functional properties of mushroom powders as a food ingredient or biologically active substance for the production of nutraceuticals.

Effects of dual modification of lysine and microwave on corn starch: In vitro digestibility and physicochemical properties

The effects of lysine addition and microwave treatment (MC) on the digestibility, physicochemical properties and structure of corn starch were investigated. Among all uncooked samples, unmodified corn starch (CS), microwave modified corn starch (MC-CS) and corn starch mixed with lysine (CS-Lys) contained 15.09 %, 14.82 % and 18.86 % slowly digestible starch (SDS), while up to 30.28 % in microwave-lysine modified corn starch (MC-Lys). In contrast to CS, the peak viscosity, breakdown viscosity, setback viscosity and gel enthalpy of MC-Lys were decreased, while the relative crystallinity was increased. Scanning electron microscopy observation showed that corn starch aggregated with each other and was coated by lysine after MC, the particle size distribution range became wider, and the specific surface area decreased. The results showed that the interaction of starch with lysine in the microwave field increased the ordered and aggregated structure of corn starch, resulting in a significant change in the physicochemical properties and digestibility of corn starch. MC-Lys can be added to foods as a nutritional fortification to meet the needs of specific populations for lysine and low carbohydrate.

Synthetic Conditions, Physical Properties, and Antibacterial Activities of Silver Nanoparticles with Exopolysaccharides of a Medicinal Fungus.

Natural polysaccharides are attractive and promising biomacromolecules for the green synthesis of silver nanoparticles (Ag NPs) with a broad spectrum of useful functions. This study aims to evaluate the synthetic conditions and physical properties of Ag NPs using three fractions of exopolysaccharide (EPS), namely EPS-1, EPS-2, and EPS-3, produced by a medicinal fungus known as Cs-HK1, with variations in their chemical composition and molecular weight. Each of the EPS fractions had a unique set of optimal synthetic conditions (reaction time course, temperature, and reagent concentration), resulting in a specific range of Ag NP size distributions. The Ag NPs synthesized with the EPS-1 fraction had the smallest particle size (~160 nm) and the most significant antibacterial activities against Escherichia coli (Gram−) and Staphylococcus aureus (Gram+), with a minimal inhibitory concentration (MIC) of 0.2 mg/mL on E. coli and 0.075 mg/mL on S. aureus. The results proved the success of the scheme of this green synthesis scheme with all three EPS fractions and the potential antibacterial application of EPS-coated Ag NPs.

Presence of spraint at bridges as an effective monitoring tool to assess current Eurasian fish otter distribution in Austria

Monitoring carnivore populations requires sensitive and trustworthy assessment methods to make reasonable and effective management decisions. The Eurasian fish otter Lutra lutra experienced a dramatic population decline throughout Europe during the twentieth century but is currently recovering in both distribution range and population size. In Austria, most assessments on otter distribution have applied a modified version of the so-called “British” or “standard” method utilizing point-wise surveys for otter spraints at predefined monitoring bridges. In this study, we synthesize several recent statewide assessments to compile the current otter distribution in Austria and evaluate the efficiency and sensitivity of the “monitoring bridge” approach in comparison to the “standard” method. The otter shows an almost comprehensive distribution throughout eastern and central Austria, while more western areas (Tyrol and Vorarlberg) are only partially inhabited, likely due to a still ongoing westward expansion. Furthermore, the bridge monitoring method utilizing presence/absence information on otter spraints reveals itself to be a time- and cost- effective monitoring tool with a tolerable loss of sensitivity for large-scale otter distribution assessments. Count data of spraints seem to be prone to observer bias or environmental influences like weather or flooding events making them less suitable for quantitative analyses.

Geological and engineering appraisal of hydraulic frac sand in some Egyptian localities as a proppant of oil well drilling

Sand that comprises high purity silica grains, in large percent, is of the best naturally occurring grains that can be used as proppants during hydraulic fracturing processes. Proppants are used to increase formations' permeability; to increase reservoirs' productivity, or to reopen plays and utilize unconventional reservoirs. The potentiality of these grains to be used as frac proppants is determined according to certain physical, mechanical, petrographical and chemical evaluations that include particle size analysis, acid solubility, turbidity, bulk density, crush resistance and hardness, sphericity and roundness, mineral and chemical composition. This study shows the evaluation of the silica sand samples collected from Malha Formation in Wadi El Dakhal, Eastern Desert; Naqus Formation in Wadi Qena, Eastern Desert; and Bahariya Formation at Gabal El-Dist area in Bahariya Oasis, Western Desert, Egypt. The samples were examined according to frac sand international standards. The results showed the potentiality of the tested samples to be utilized as frac sand proppants. Wadi El-Dakhal and Wadi Qena studied areas possess very promising samples for frac sand production. But, the quality of Wadi El-Dakhal samples is somewhat better than that of Wadi Qena samples. The samples of Gabal El-Dist in Bahariya Oasis are relatively less to achieve the requirements; however, they can be utilized in shallow depths.The assessment testing of the studied samples revealed a good results and verifying the standard requirements, where SiO2 content is 89.1% in Wadi Qena, 99.3 % in Wadi Dakhal and 78.1% in Gebel El Dist, crush resistance at 5000 psi gives fine percent 4.71 W.Q, 6.78 W.D, and 14.11 B.O, turbidity readings raining from 100.5 to 133.25 NTU, the grain roundness are rounded to sub rounded, and grain size distribution range is 30/50 to 40/70 grading (710 um to 210 um).

Hierarchical porous nanofibrous aerogels with wide-distributed pore sizes for instantaneous organophosphorus pesticides decontamination-and-fluorescence sensing

Acute and persistent pesticides extensively used in agricultural production, especially organophosphorus pesticides (OPPs), pose serious safety concerns to humans and ecosystems. Porous adsorbents have shown promising performance on OPPs removal from water streams, but challenges remain for integrating these materials into a continuous network with easy handling and recyclability without sacrificing their rapid and massive adsorption ability. Here, we report a monomer penetration-determined in situ synthesis methodology to create a hierarchical porous structure with wide-distributed pore size by compositing triazine-based porous organic polymers on bacterial cellulose nanofibrous aerogels. The co-existence of meso/macro/supermacropores in the composites enables superior adsorption performance by alleviating mass transfer resistance but ensuring numerous adsorption sites. Based on experimental characterizations, the as-fabricated composites exhibit integrated properties of high porosity with a wide range of pore size distribution, high surface area (391 m2/g), superior OPPs affinity, and OPP-triggered fluorescence responsibility, which are extraordinarily effective serving as adsorbents, filters, wipers, and fluorescence sensors to address OPP contaminations in the environment and food industry. The successful fabrication of such materials is expected to inspire the development of novel materials with dual-function of “decontamination-and-sensing” for a broader application.

Quantitative evaluation of pore structures within micron-scale laminae of lacustrine shales from the Second Member of the Kongdian Formation in Cangdong Sag, Bohai Bay Basin, China

Lamina is the basic and typical “building block” of organic-rich shales, which has significant impact on the generation, migrition, and accumulation of hydrocarbon. Integrated methods, including X-ray diffraction (XRD), scanning electron microscopes (SEM), and image processing technology, were applied to explore the pore type, pore size, and pore morphology of laminae in shales selected from the Second Member of the Kongdian Formation in Bohai Bay Basin. The application of image stitching and processing technology intuitively and accurately obtained the pore structure among different types of laminae including siliceous laminae, mixed laminae, dolomite laminae, and calcite laminae. The results showed that the average SEM-based surface porosity of laminae was in the following order: siliceous laminae > calcite laminae > dolomite laminae > mixed laminae. The siliceous lamina was dominated by interparticle pores between rigid grains, and was characterized by high volume of macropore. In addition to the pores between rigid grains, pores between clay platelets resulted in a large volume of nano-scale pores. Therefore, mixed lamina was characterized by the smallest average pore diameter and the lowest SEM-based surface porosity. The SEM-based surface porosity of calcite lamina and dolomite lamina was between that of siliceous lamina and mixed lamina, and abundant interparticle pores between grains and intraparticle pores within carbonate minerals were observed in calcite lamina and dolomite lamina. The porosity and pore type of calcite laminae are similar with that of dolomite laminae in certain aspects, while the pore size distribution range of dolomite lamina was wider than that of calcite lamina and the dissolution pores of the calcite lamina contributed more pore volume than that of dolomite lamina. Diverse pore structures among different laminae may be attribute to the synergistic effect of different mineral compositions and diagenetic processes.

Coarse-grained CFD-DEM study of Gas-solid flow in gas cyclone

Gas cyclones are common device in various industries to separate solid particles and/or droplets from gas streams. Nonetheless, the mathematical modelling of gas cyclone has been very challenging since huge number of multi-sized particles are involved in the system. In this work, a numerical study of the gas–solid flow in a gas cyclone with wide range of particle size distribution (from 1 to 200 µm) is carried out by developing a coarse-grained combined Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) model. It shows that the coarse-grained CFD-DEM model is able to capture the typical flow features in a gas cyclone including the solid strands and dust ceiling phenomena. It also shows that modelling of van der Waals force is critical for the prediction of separation efficiency in gas cyclone especially for fine particles. Furthermore, it is tried to explain how the dust ceiling is formed.

Multi-Scale Pore Structure Characterization of Silurian Marine Shale and Its Coupling Relationship With Material Composition: A Case Study in the Northern Guizhou Area

Investigation of pore structure is vital for shale reservoir evaluation and also “sweet spot” prediction. As the strong heterogeneity in pore types, morphology, and size distributions of organic matter-rich shales, it is essential to combine different approaches to comprehensively characterize them.Field emission-scanning electron microscopy (FE-SEM), low-pressure gas (CO2 and N2) adsorption, and high-pressure mercury intrusion (HPMI) were employed to systematically investigate the pore structure of the lower Longmaxi shale reservoirs in the northern Guizhou area. The results show that the shales can be divided into four lithofacies based on mineral composition, namely, siliceous shale (SS), clay shale (CS), carbonate shale (CAS), and mixed shale (MS), among which siliceous shale is the primary lithofacies of the Longmaxi shale. Numerous organic matter (OM)-hosted pores, clay interlayer pores, interparticle pores, and intraparticle pores were identified within shale reservoirs. The specific surface area ranges from 11.3 to 27.4 m2/g, with an average of 18.1 m2/g. It exhibits a strong positive correlation with TOC contents, suggesting that organic matter is the major contributor to the specific surface areas. A wide range of pore size distribution was measured by integration of gas adsorption and HPMI. It is shown that the pore size is primarily distributed within ∼100 nm, corresponding to micropores, mesopores, and part of macropores. The total pore volume, which is mostly derived from the contribution of micropores and mesopores, remains within a range of 0.11 to 0.025 ml/g, with an average of 0.018 ml/g. Furthermore, the volume of micropores and mesopores is mainly controlled by organic matter contents. The dissolution pore contributes most to the macropore space within shale reservoirs, based on the positive correlation with macropore volume and easily dissolved minerals, including carbonate and feldspar. Also, the total pores volume is mainly dominated by organic matter and carbonate contents. This is possibly attributed to the easily dissolved and rigid features of carbonate, which can protect the primary interparticle pores due to its high compression resistance and is conducive to forming abundant dissolution pores. OM-rich carbonate-bearing mixed shale may be the most favorable lithofacies for gas storage in the northern Guizhou area.

Использование наноразмерного ZnO в составах для защитной обработки древесины

Wood natural structure can be considered as a suitable matrix for modifying with nanoparticles of various chemical nature. The research aims at obtaining a woodbased nanocomposite by modifying wood with compositions of waste vegetable oil and zinc oxide nanoparticles and studying the properties of this nanocomposite. Silver birch (Betula pendula) wood samples were chosen as study objects. Refined sunflower oil left after cooking was the oil base of the developed impregnating compositions; nanosized zinc oxide powder was the filler and modifier. The sol-gel method providing a narrow range of particle size distribution was used for synthesis of zinc oxide nanoparticles from Zn(NO3)2·6H2O as starting material. Aqueous ammonia solution was used as a precipitant. The synthesized zinc oxide nanoparticles contained no impurities, were mostly spherical and had the size less than 20 nm. The size of zinc oxide agglomerates was no more than 100 nm, allowing them to easily penetrate into the wood material cavities. A stable suspension of synthesized zinc oxide nanopowder in used sunflower oil was prepared and applied for wood modification by hot-and-cold bath treatment. It was found that the use of nanoscale zinc oxide accelerates the drying process of vegetable oil coating, increases the strength of such a coating and its resistance to external influences. The use of developed compositions improves the hydrophobic properties of wood, its moisture and water resistance, as well as reduces swelling in the tangential and radial directions. We have chosen the optimal dosage of nanosized zinc oxide (0.1 %) in compositions based on waste vegetable oil for protective treatment of birch wood. Impregnating compositions on the base of waste vegetable oil are environmentally safe and their use allows recycling food industry wastes.

Can size distributions of European lake fish communities be predicted by trophic positions of their fish species?

An organism's body size plays an important role in ecological interactions such as predator–prey relationships. As predators are typically larger than their prey, this often leads to a strong positive relationship between body size and trophic position in aquatic ecosystems. The distribution of body sizes in a community can thus be an indicator of the strengths of predator–prey interactions. The aim of this study was to gain more insight into the relationship between fish body size distribution and trophic position in a wide range of European lakes. We used quantile regression to examine the relationship between fish species' trophic position and their log‐transformed maximum body mass for 48 fish species found in 235 European lakes. Subsequently, we examined whether the slopes of the continuous community size distributions, estimated by maximum likelihood, were predicted by trophic position, predator–prey mass ratio (PPMR), or abundance (number per unit effort) of fish communities in these lakes. We found a positive linear relationship between species' maximum body mass and average trophic position in fishes only for the 75% quantile, contrasting our expectation that species' trophic position systematically increases with maximum body mass for fish species in European lakes. Consequently, the size spectrum slope was not related to the average community trophic position, but there were negative effects of community PPMR and total fish abundance on the size spectrum slope. We conclude that predator–prey interactions likely do not contribute strongly to shaping community size distributions in these lakes.

Phytoplankton size distributions in the western North Atlantic and their seasonal variability

AbstractPhytoplankton play a major role on Earth, impacting the global distribution and cycles of carbon, oxygen, nitrogen, sulfur, and other elements, and structuring marine food webs. One fundamental trait of phytoplankton with direct biogeochemical implications is their size, as it governs metabolic and sinking rates as well as prey–predator interactions. Phytoplankton size spans approximately 3.5 orders of magnitude (when expressed as an equivalent spherical diameter), and thus measuring the full range in size distribution of phytoplankton is challenging and rarely attempted. Here, we constructed phytoplankton size spectra by merging state‐of‐the‐art cytometry and imaging cytometry measurements that were collected in the western North Atlantic Ocean, along a latitudinal gradient (36°N to 55°N) and during different phases of the annual cycle of phytoplankton. The derived spectra show a seasonal pattern that parallels changes in phytoplankton biomass, and do not always follow a commonly assumed power‐law model. Shifts in size spectra were more pronounced in the sub‐Arctic and temperate subregions, compared to the subtropical region of the study area. We evaluated the relationships between different size groups and environmental parameters to derive ecologically meaningful size groups. Finally, to simulate Ocean Color remote‐sensing algorithms of phytoplankton size, we compared temporal variations in descriptors of the size spectra (median particle size, phytoplankton size distribution exponent) with optical size proxies derived from light absorption and attenuation; good agreement was observed in the northern sections of the study area where temporal changes in community size structure were more pronounced.

The Darwinian shortfall in plants: phylogenetic knowledge is driven by range size

The Darwinian shortfall, i.e. the lack of knowledge of phylogenetic relationships, significantly impedes our understanding of evolutionary drivers of global patterns of biodiversity. Spatial bias in the Darwinian shortfall, where phylogenetic knowledge in some regions is more complete than others, could undermine eco‐ and biogeographic inferences. Yet, spatial biases in phylogenetic knowledge for major groups – such as plants – remain poorly understood. Using data for 337 023 species (99.7%) of seed plants (Spermatophyta), we produced a global map of phylogenetic knowledge based on regional data and tested several potential drivers of the observed spatial variation. Regional phylogenetic knowledge was defined as the proportion of the regional seed plant flora represented in GenBank's nucleotide database with phylogenetically relevant data. We used simultaneous autoregressive models to explain variation in phylogenetic knowledge based on three biodiversity variables (species richness, range size and endemism) and six socioeconomic variables representing funding and accessibility. We compared observed patterns and relationships to established patterns of the Wallacean shortfall (the lack of knowledge of species distributions). We found that the Darwinian shortfall is strongly and significantly related to the macroecological distribution of species' range sizes. Small‐ranged species were significantly less likely to have phylogenetic data, leading to a concentration of the Darwinian shortfall in species‐rich, tropical countries where range sizes are small on average. Socioeconomic factors were less important, with significant but quantitatively small effects of accessibility and funding. In conclusion, reducing the Darwinian shortfall and smoothen its spatial bias will require increased efforts to sequence the world's small‐ranged (endemic) species.