Changes In Size Distribution Research Articles

Development of propranolol loaded SLN for transdermal delivery: in-vitro characterization and skin deposition studies.

The study aimed to formulate solid lipid nanoparticles (SLNs) for the transdermal delivery of PPL to improve skin retention and efficacy. The particle size distribution of SLNs was determined and the morphology of SLNs was also analyzed by SEM. In-vitro, ex-vivo and in vivo evaluations were done for PPL loaded SLN. The safety of drug delivery systems was assayed using MTT test. The results indicated successful encapsulation of PPL in SLNs (59.38%), which exhibited a spherical shape and smooth surface. Compared to PPL solution, SLNs demonstrated a prolonged drug release profile in vitro. Stability tests over three months showed no significant changes in entrapment efficiency or size distribution. Enhanced permeation through shed snake and rat skin was observed with SLNs compared to the PPL solution. Ex-vivo and in vivo studies confirmed that PPL-loaded SLNs significantly increased drug content in the skin. Importantly, the SLNs displayed biocompatibility, as no significant cytotoxic effects were noted, and they were nonirritating to rat skin. To the best of our knowledge, this is the first study that indicates SLNs can be considered as a promising nanocarriers for transdermal delivery of PPL.

Asynchronous shifts in the demographics of two wave-swept kelp species (Laminariales) after nearly four decades.

Kelp forests are among the most abundant and productive marine ecosystems but are under threat from climate change and other anthropogenic stressors. Although knowledge is growing about how the abundance and distribution of kelp forests are changing, much less is known about the "non-lethal" effects that global change is having on the performance and health of kelp populations in areas where they persist. Here we assessed the age distribution of two common stipitate kelp species, Laminaria setchelli and Pterygophora californica, at Wizard Islet in Barkley Sound, British Columbia, Canada, and compared these data to historical demographic data collected by De Wreede (1984) and Klinger and DeWreede (1988) from the same site between 1981 and 1983. We observed that L. setchelli populations in 2020 were younger and less evenly aged than the same populations sampled nearly four decades prior, while the P. californica population was composed of older individuals on average than at the historical time point. Although the drivers of these demographic changes remain unclear, Barkley Sound has experienced substantial changes in the physical and biological environment over the past decade that could be responsible for these patterns. Given that the size of an individual and its probability of reproduction increases with age, shifting demographics may impact the reproductive output of each population, potentially altering the competitive relationships between co-occurring species. Changes in size distribution may also influence ecosystem-level processes such as habitat complexity or productivity.

Chemical Transformation of Vaping Emissions under Indoor Atmospheric Aging Processes.

E-cigarette emissions, which contain a variety of hazardous compounds, contribute significantly to indoor air pollution and raise concerns about secondhand exposure to vaping byproducts. Compared to fresh vape emissions, our understanding of chemically aged products in indoor environments remains incomplete. Terpenes are commonly used as flavoring agents in e-liquids, which have the ability to react with the dominant indoor oxidant ozone (O3) to produce reactive oxygenated byproducts and result in new particle formation. In this study, mixtures of propylene glycol (PG), vegetable glycerin (VG), and terpenes as e-liquids were injected into a 2 m3 FEP chamber to simulate the indoor aging process. 100 ppbv O3 was introduced into the chamber and allowed to react with the fresh vape emissions for 1 h. Complementary online and offline analytical techniques were used to characterize the changes in the aerosol size distribution and chemical composition during the aging processes. We observed more ultrafine particles and a greater abundance of highly oxygenated species, such as carbonyls, in aged e-cigarette aerosols. Compared with their fresh counterparts, the aged emissions exhibited greater cytotoxic potential, which can be attributed to the formation of these highly oxygenated compounds that are not present in the fresh emissions. This work highlights the dynamic chemistry and toxicity of e-cigarette aerosols in the indoor environment as well as the indirect risks of secondhand exposure.

Time-varying quantitative characterization of reservoir microscopic pore structure based on digital core

The reservoir physical parameters (such as porosity, permeability, phase permeability, etc.) will change in the process of water injection development with the continuous flushing effect of high magnification water drive, which may have adverse effects on development if they cannot be accurately characterized. In this paper, we try to quantitative characterize the time -varying features of pore structure from the microscopic perspective. We used high-resolution 3D micro-CT (MCT) images to supplement the analysis of the physical properties of the rocks, and we used 3D pore network modeling technology to generate a 3D model of the rock samples. Then the relevant static micro-pore parameters are derived to study the changes of rock properties in different periods of development. Pore parameters were obtained to study the changes in porosity, permeability and pore size distribution of the rocks under different expulsion multiples, and to visualize the time-varying pattern of the microstructure of the rock samples under different stages of water injection. Under low-multiple water-driven conditions (10 PV), the physical properties of the rock samples did not change significantly, with an average facies change of only 1.98%. When reaching high multiples of water drive (more than 500PV), the change rate reaches more than 15%. And with the increase of water drive multiples, the distribution of pore radius and throat radius of rock samples showed an obvious right-shift trend, and the pores and throats increased, which was consistent with the results of CT scanning photographs. Equation fitting of the simulation results reveals that the core micro-parameters show an overall logarithmic relationship with the change of water drive. In this paper, a new application of Micro CT is provided to quantify the microstructure of water-injected reservoirs. By adopting this method, the effect of water-drive multiplicity on reservoir structure can be illustrated from a microscopic perspective. Meanwhile, compared with previous studies, this paper further investigates the effect of time-variation based on the qualitative analysis of the effect of time-variation of water-driven in reservoirs, and regresses time-variation curves and formulas through the changes in multiple water-driven states, which fills in the gap of the current lack of quantitative research and provides new understanding and optimization of the development of oilfields. The study will provide a new perspective for understanding and optimizing oilfield development.

Nebulized Lipid Nanoparticles Based on Degradable Ionizable Glycerolipid for Potent Pulmonary mRNA Delivery.

As an advanced nucleic acid therapeutical modality, mRNA can express any type of protein in principle and thus holds great potential to prevent and treat various diseases. Despite the success in COVID-19 mRNA vaccines, direct local delivery of mRNA into the lung by inhalation would greatly reinforce the treatment of pulmonary pathogens and diseases. Herein, we developed lipid nanoparticles (LNPs) from degradable ionizable glycerolipids for potent pulmonary mRNA delivery via nebulization. A panel of proprietary ionizable glycerolipids with branched tails and five ester bonds were developed through a three-step esterification reaction, and LNPs formed from a lead glycerolipid identified as TG4C enabled highly efficient in vivo mRNA delivery via systemic administration with around 6-fold higher luciferase protein expression than commercial LNPs from SM102 and Dlin-MC3-DMA (MC3). Formulation screening revealed that LNPs formed at a TG4C:DOPE:cholesterol:DMG-PEG molar ratio of 50:10:38.5:1.5 (TG4C-LNPs4) had high stability against nebulization with slight changes of size distribution and mRNA encapsulation efficiency, and the nebulized TG4C-LNPs4 afforded an equivalent percentage of positive cells and a slightly lower EGFP fluorescence intensity in lung cell lines (A549, BEAS-2B). Following pulmonary delivery in mice, TG4C-LNPs4 induced efficient transfection in the majority of epithelial cells in the lung, leading to apparent bioluminescence evenly distributed in all five lung lobes. In an elastase-induced emphysema model in mice, TG4C-LNPs4 loaded with mRNA encoding hepatocyte growth factor could significantly suppress the secretion of inflammatory cytokines (IL-1β, IL-6, and TNF-α) in bronchoalveolar lavage fluid and counteract the alveoli wall thinning. Notably, partial substitution (25%) of cholesterol with budesonide, an anti-inflammatory glucocorticoid, in TG4C-LNPs4 generated equivalent protein expression and significantly improved therapeutic efficacy. Taken together, our study provides robust and high-performing nanovehicles based on degradable ionizable glycerolipids, enabling potently local mRNA delivery to the lung for the treatment of pulmonary diseases.

Polymer Solutions in Microflows: Tracking and Control over Size Distribution

Microfluidics provides cutting-edge technological advancements for the in-channel manipulation and analysis of dissolved macromolecular species. The intrinsic potential of microfluidic devices to control key characteristics of polymer macromolecules such as their size distribution requires unleashing its full capacity. This work proposes a combined approach to analyzing the microscale behavior of polymer solutions and modifying their properties. We utilized the idea of modeling cross-channel diffusion in polydisperse polymer microflows using dynamic light scattering size distribution curves as the source data. The model was implemented into a Matlab script which predicts changes in polymer size distribution at microfluidic chip outputs. We verified the modeling predictions in experiments with a series of microchips by detecting the optical responses of injected nematic liquid crystals in the presence of microfluidic polymer species and analyzing the polymer size distribution after microfluidic processing. The results offer new approaches to tuning the size and dispersity of macromolecules in solution, developing auxiliary tools for such techniques as dynamic light scattering, and labs-on-chips for the combined diagnostics and processing of polymers.

Numerical simulation of aerosol concentration effects on cloud droplet size spectrum evolutions of warm stratiform clouds in Jiangxi, China

Abstract. Changes in aerosol amount and size distribution significantly impact cloud droplet size distribution, as aerosols act as cloud condensation nuclei (CCNs) and influence the relative dispersion (ε) of cloud droplet spectra. Relative dispersion plays a key role in parameterizing cloud processes in general circulation models (GCMs) and microphysical schemes, affecting precipitation estimates and climate predictions. However, the effects of varying aerosol modes on cloud microphysics remain debated, depending on thermodynamic conditions and cloud type. This study simulates a warm stratiform cloud in Jiangxi, China, using the Weather Research and Forecasting (WRF) Spectra–Bin Microphysics scheme (SBM-FAST) from 18:00 on 24 December 2014 to 06:00 on 25 December 2014 (UTC). Satellite and aircraft observations were used to validate the simulation, showing good agreement in cloud structure. Sensitivity experiments were conducted by increasing nucleation, accumulation, and coarse-mode aerosols 5-fold and by reducing the total aerosol concentration to 1/5 of the control. Results show that higher aerosol concentrations enhance cloud formation and broaden droplet spectra, while lower concentrations suppress cloud development. Accumulation-mode aerosols increase small-droplet concentrations, while nucleation- and coarse-mode aerosols favor larger droplets. The correlation between ε and volume-weighted radius (Rv) shifts from positive to negative as Rv increases. This transition is driven by cloud droplet collision–coalescence, condensation, and activation. Increased accumulation-mode aerosol concentrations shift the ε–Rv correlation from negative to positive in the Rv range of 4.5–8 µm, while reduced aerosol concentrations strengthen the negative correlation. Regardless of different coalescence intensities, ε converges with the increase in number concentration of cloud droplets (Nc).

Effects of high-pressure and CaCl2 pretreatments on the salt taste-enhancing activity of hydrolysate derived from spent hen meat.

High-sodium intake has been proven to bring serious risks to public health. A potential sodium substitute of salt taste-enhancing hydrolysate (STEH) of protein has been focused on recently. The salt taste-enhancing activity (STEA) of STEH still needs to be improved. High-pressure and calcium chloride (CaCl2) pretreatments were reported to affect proteolysis and promote the release of bioactive peptides. Hence, we investigated effects of high-pressure and CaCl2 pretreatments on hydrolysis and STEA of STEH derived from spent hen. The pretreatments significantly influenced STEA of spent hen meat hydrolysate (SHH), especially 200 MPa pressure and 80 mmol L-1 CaCl2 pretreatments increased 27.1% salt taste intensity of SHH compared to that of blank (without pretreatments) according to sensory evaluation, the SHH umami also increased after pretreatments. In SHH, the proportion of peptides < 1000 Da increased up to 79.37% after the pretreatments compared to 73.68% of the blank. The degree of hydrolysis (DH) increased to 19.45% for moderate high-pressure (200 MPa) from 18.02% for blank, and the DH decreased after higher high-pressure and CaCl2 pretreatments, especially for CaCl2 in 80 mmol L-1. The change in particle size distribution of SHH has similar trends to DH. High-pressure and CaCl2 pretreatments increased STEA of SHH by affecting hydrolysis process. The STEA increase may be related to increased small-peptide proportion in SHH. Meanwhile, moderate high-pressure may promote protein unfolding and further increase DH according to particle size distribution of SHH. The combination of proteolysis and pretreatments of high-pressure and CaCl2 is a promising method to produce STEH. © 2024 Society of Chemical Industry.

Effect of particle gradation and rock block content on soil-rock mixture shear strength parameters

Soil-rock mixture (SRM) is highly inhomogeneous and loose geomaterial found in the quaternary formation, composed of a certain percentage of rock blocks, fine-grained soil, and pores. In Peninsular Malaysia, SRM can commonly be found in the granitic formation covering the mountainous areas where slope failures are prone to occur due to deep tropical weathering, heavy rainfall, and steep terrain. Numerous research studies have been conducted to investigate the mechanical behaviour of SRM, especially the influence of rock block content. However, the effect of particle size distribution has been studied in limited detail. This study uses sieve analysis, specific gravity, compaction, and direct shear box tests to determine the shear strength parameters of weathered type SRM with particle size distribution. The sample collected was divided into well-graded, poorly-graded, and gap-graded types of particle size distribution with 30%, 50%, and 70% rock block content, respectively. The percentage of rock block content is crucial in controlling the shear strength parameters. The specific gravity, dry density, optimum moisture content, and estimated porosity values measured show a considerable difference when the particle size distribution (PSD) and rock block content change. The findings also show that for a well-graded SRM, cohesion and friction angle values show a non-linear relationship against the rock block content. Meanwhile, as the rock block content increases, the cohesion decreases and inversely has an increment of friction angle for poorly-graded SRM. In contrast, the cohesion of gap-graded SRM increases when the rock block content increases. Hence, by understanding the influence of particle size distribution on the shear strength parameters of SRM, a better evaluation can be made in designing slope hazard mitigation.

Technology for removing PM2.5 in clean coal processes

Most countries primarily utilize thermal power to meet their energy needs. However, thermal power generation generates a substantial amount of pollutants, such as particulate matter (PM), SOX, and NOX. These pollutants not only damage backend turbines and related equipment but also pollute the environment; thus, controlling their emissions is critical.This study developed a system operating under high temperature by integrating heating, pneumatic conveying, dust particulate supply, and filter material transport systems. This setup enables the simulation of the entry of syngas with PM at the output of a gasification unit. The developed composite filtration system was analyzed under various operational parameters, including different temperatures, inlet air velocities, and mass flow rates of filter material, to examine the changes in the dust particulate size distribution at its outlet and its PM2.5 collection efficiency. In a series of tests, the collection efficiency of this system reached at least 95% at operating temperatures between 20°C and 600°C. Each 100°C increase in the operating temperature resulted in a 0.63% decrease in the PM2.5 collection efficiency. The findings of this study lay the foundation for the future development of high-temperature gas purification systems.

Study on aerodynamic breakup of non-Newtonian liquid droplets and the distribution characteristics of their sub-droplets

In industrial applications, the secondary breakup of droplets and the size distribution of their sub-droplets are crucial for atomization performance indicators. In this work, a high-speed digital camera is utilized to experimentally and theoretically study the secondary breakup process of xanthan gum (XG) droplets and the size distribution changes of resulting sub-droplets in continuous airflow by changing the Weber number and effective Ohnesorge number. In addition, a detailed study is conducted on the liquid ring with the highest liquid content. The results show that at low Weber numbers, the number of nodes generated at the XG droplet ring is the same as that of the water droplet, following “the combined R-T/aerodynamic drag” mechanism. However, the final diameter of the nodes differs significantly from that of the water droplet. The particle size of XG liquid ring nodes is not only affected by the Weber number but also decreases with the increase of the effective Ohnesorge number. The particle size of the remaining broken sub-droplets in the liquid ring decreases with the increase of the effective Ohnesorge number. Finally, the spatial range of droplet breakup under different parameters is described by using the liquid ring breakup angle, and it is found that the breakup angle of the liquid ring is mainly related to the breakup mode.

Detection and analysis of ship emissions using single-particle mass spectrometry: A land-based field study in the port of rostock, Germany

The regulation of ship emissions has become more restrictive due to their significant impact on global air quality, particularly in coastal regions. According to the International Maritime Organization (IMO) regulations, current restrictions mainly limit the sulfur content of the fuel mass to 0.5 % and 0.1 % respectively. In compliance with these regulations, exhaust SO2 cleaning systems (scrubbers) and new low-sulfur fuels are increasingly used. For comprehensive monitoring of ship emissions, advanced measurement techniques are demanded. Our study reports on the results of a land-based field campaign conducted in the port of Rostock, Germany. The chosen location strategically positions the measurement setup to capture all incoming and outgoing ships passing within a distance of up to 2 km. Potential ship exhaust plumes are indicated by rapid changes in particle number and size distribution monitored by an optical particle sizer (OPS) and a scanning mobility particle sizer (SMPS). Additionally, single-particle mass spectrometry (SPMS) was used to qualitatively characterize ambient single-particles (0.2–2.5 μm) by their chemical signatures. In a one-week time span, the exhaust plumes of 73 ships were identified. The high sensitivity of SPMS to transition metals and polycyclic aromatic hydrocarbons (PAH) in individual particles make it possible to distinguish between different marine fuels.

Pilot-scale study of turbid particle evolutional/removal characteristics during coagulation-sedimentation-filtration (CSF): Effects of coagulant dosage and secondary dosing after breakage

Considering the limitations of treated water turbidity, a thorough understanding of the changes in turbid particle size distribution during coagulation-sedimentation-filtration (CSF) is crucial for enhancing the removal efficiency of particulate and dissolved contaminants from raw water. In this study, a pilot-scale experimental system was utilized to track the evolution of turbid particles and assess how the characteristics of these turbid particles affected the quality of treated water in the CSF processes under varying cases of polyaluminum chloride (PAC) coagulant dosage and secondary coagulant dosage after breakage. It was found that differently from the role of PAC coagulant dosage (without high-shear breakage), different levels of secondary coagulant dosing after breakage had minimal influence on the aggregate structure produced by mechanical stirring flocculation. During the overall CSF processes, the changing trend in the total particle number for the filtered water appeared to be more consistent with the corresponding changing trend for the settled water, as the PAC coagulant dosage increased. In addition, the combined effects of shear-induced breakage and secondary dosing could not only improve the removal efficiency of organic matter after inclined-tube sedimentation following mechanical stirring flocculation, but also enhance the removal efficiencies of water turbidity and particulate matter through sand filtration. In order to reduce the frequency of backwashing and extend the service life of the filter media, greater emphasis should be placed on detecting and removing the number of smaller-sized particles existing in the sixth unit of the flocculation tank together with the effluent of the sedimentation tank.

Effects of In-Row Spacing on Yield, Tuber Size Profiles, Bruise Damage, and Crop Values for Cultivars Alturas, Clearwater Russet and Ranger Russet in the Columbia Basin

Variety selection and cultural management practices are the most common considerations for improved profitability in potato production systems. Planting density investigations have led to both within and between-row spacing recommendations to maximize profitability for commonly grown potato cultivars. Planting density can significantly alter tuber set, tuber size distribution, yield and profitability depending on end-use of the crop. However, rarely have such investigations included an assessment of the residual effects of changes in tuber size distribution on tuber bruising (blackspot and shatter bruise) and associated financial returns. The physics of impact injury suggests that larger tubers are more prone to tuber bruising than smaller tubers when dropped from a similar height. In this study we varied the in-row spacing of seed to investigate the extent to which the associated changes in tuber size distribution affect tuber bruising and crop values. The results demonstrated that: (1) the extent of tuber bruising was directly correlated with total marketable yield as altered by in-row spacing; (2) marketable yields decreased as in-row spacing increased; (3) while the absolute yield (MT ha−1) of bruised tubers increased with closer in-row spacing, the spacing-induced shifts in tuber size distribution had no effect on the percentage of bruised tubers as a proportion of total yield; (4) larger tubers were more prone to bruising; and (5) closer in-row spacing significantly improved financial returns for both processing and seed contracts despite the increase in bruise yield.

Changes of gluten protein composition during sourdough fermentation in rye flour

AbstractBackground and ObjectivesCeliac disease (CD) is an immune‐mediated condition triggered by gluten consumption. Although more studies stated that gluten proteins are partially degrading during sourdough fermentation, it is still unclear whether the CD toxic epitopes are affected. Our aim was to examine the effect of controlled sourdough fermentation on the gluten content and composition with different sourdough starters in rye flour.FindingsDespite significant changes in protein size distribution and a decrease in secalin types confirmed by high‐performance liquid chromatography methods, the enzyme‐linked immunosorbent assay results showed increased gluten content after fermentation. The incomplete degradation of gluten and the potential resistance of celiac toxic epitopes may explain our results. As part of the R5 antibody binding, epitopes are supposed to be unavailable in the native form of secalins; they might be released and become accessible in the smaller protein fragments.ConclusionsIn comparison of the effect of different starter cultures, the results show that the different microbiological composition of the sourdough samples might be the reason for the differences in the protein degradation.Significance and NoveltyResults highlight the importance of a deeper investigation of the effects of gluten protein degradation on CD toxicity and the standardization of the fermentation process.

Functional variations in efficiency of PSII during leaf ontogeny in the tropical plant Saraca asoca

Leaf ontogeny of tropical evergreen tree species lasts several months with changes in size, shape, colouration and internal tissue distribution of leaves. Leaf initiation in Saraca asoca generally occurs once in a year during February–April, followed by very limited leafing thereafter. We measured the rate of photosynthesis, chlorophyll a fluorescence, energy quenching and PSII functions during the leaf ontogeny process. Observations were taken up to 35 days after opening of lamina (DAOL). Significant increase in the synthesis and accumulation of photosynthetic pigments but negative net photosynthesis was noticed during initial days of the ontogeny. The leaf moved from heterotrophy to autotrophy with gradual improvement of PSII functions. The ratio of intercellular CO2 (Ci) and ambient CO2 (Ca) showed significant change at ≥11 DAOL. Increase in the age of the leaf (between 5 and 28 DAOL) caused decrease in O-J rise and corresponding increase in J-I and I-P rise as well as of fluorescence maximum (FM) of the OJIP curve. The improvement of the electron transport components of the donor side of PSII was seen with increase in the functional oxygen evolving complex. The functional improvements of the donor and acceptor side of PSII during leaf ontogeny are discussed.

Impact of PCLNPG Nanopolymeric Additive on the Surface and Structural Properties of PPSU Ultrafiltration Membranes for Enhanced Protein Rejection

This research explored the use of a partially cross-linked graft copolymer (PCLNPG) as an innovative nanopolymer pore-forming agent to enhance polyphenylsulfone (PPSU) membranes for protein separation applications. The study systematically examined the impact of incorporating PCLNPG at varying concentrations on the morphological and surface properties of PPSU membranes. A thorough characterization of the resulting PPSU-PCLNPG membranes was performed, focusing on changes in morphology, water affinity, porosity, pore size, and pore size distribution. The experimental findings demonstrated that the use of PCLNPG led to a significantly more porous structure, as confirmed by SEM analysis, with notable increases in porosity and pore size (nearly double). Additionally, the hydrophilicity of the PPSU membrane was remarkably enhanced. Performance evaluations revealed a substantial improvement in pure water flux, with the flux nearly tripling. The BSA retention was directly correlated with the concentration of the PCLNPG pore former for a loading range of 0.25–0.75 wt.%. The incorporation of PCLNPG also reduced the membrane fouling propensity by reducing both cake layer resistance (Rc) and pore plugging resistance (Rp). These results underscore the potential of PCLNPG-PPSU membranes for wastewater reclamation and nutrient recovery applications.

Effects of Mesozooplankton Growth and Reproduction on Plankton and Organic Carbon Dynamics in a Marine Biogeochemical Model

AbstractMarine mesozooplankton play an important role for marine ecosystem functioning and global biogeochemical cycles. Their size structure, varying spatially and temporally, heavily impacts biogeochemical processes and ecosystem services. Mesozooplankton exhibit size changes throughout their life cycle, affecting metabolic rates and functional traits. Despite this variability, many models oversimplify mesozooplankton as a single, unchanging size class, potentially biasing carbon flux estimates. Here, we include mesozooplankton ontogenetic growth and reproduction into a 3‐dimensional global ocean biogeochemical model, PISCES‐MOG, and investigate the subsequent effects on simulated mesozooplankton phenology, plankton distribution, and organic carbon export. Utilizing an ensemble of statistical predictive models calibrated with a global set of observations, we generated monthly climatologies of mesozooplankton biomass to evaluate the simulations of PISCES‐MOG. Our analyses reveal that the model and observation‐based biomass distributions are consistent ( = 0.40, total epipelagic biomass: 137 TgC from observations vs. 232 TgC in the model), with similar seasonality (later bloom as latitude increases poleward). Including ontogenetic growth in the model induced cohort dynamics and variable seasonal dynamics across mesozooplankton size classes and altered the relative contribution of carbon cycling pathways. Younger and smaller mesozooplankton transitioned to microzooplankton in PISCES‐MOG, resulting in a change in particle size distribution, characterized by a decrease in large particulate organic carbon (POC) and an increase in small POC generation. Consequently, carbon export from the surface was reduced by 10%. This study underscores the importance of accounting for ontogenetic growth and reproduction in models, highlighting the interconnectedness between mesozooplankton size, phenology, and their effects on marine carbon cycling.

Burning effects on the soils of the Mexican Maya Lowlands: Current evidence for understanding past events

The slash-and-burn cultivation system is a millenarian practice still used in many countries today, with significant environmental impacts. However, identifying evidence of this agricultural method in soil records is challenging due to natural and human factors that can obscure or alter fire signals. This challenge is particularly evident in the Yucatán Peninsula, where the ancient Maya practiced slash-and-burn agriculture in a dynamic tropical karst environment, making it difficult to pinpoint the origins and consequences of this practice. In this study, we use a recent agricultural burning in a karstic landscape in Chiapas as a model to understand alterations in soil properties. We then apply these insights to identify similar features at a Maya site on the Yucatán Peninsula, specifically at Coyote Quarry. For both cases, we conducted micromorphological analysis, soil physical-chemical characterization, thermogravimetry and differential scanning calorimetry analysis, and radiocarbon dating of mollusk shells, soil organic carbon, and charcoal fragments (the latter exclusively at Coyote Quarry). Our findings reveal significant effects on the soils from the Chiapas site post-burning, including changes in grain size distribution, pH, and total organic and inorganic carbon. These results were compared to those obtained from the Coyote Quarry soils and pedosediments. Key findings include micromorphological features, the presence of charcoal and other burned materials, and pyrogenic carbon identified through thermal analyses. The preservation of these burned features was facilitated by the typical karstic vertical soil erosion and redeposition as pedosediments in karstic depressions. The intrinsic association of the fire signals found in these karstic sinkholes and their radiocarbon dates enables us to link this evidence to the initiation of slash-and-burn agriculture by the Maya in the Yucatán Peninsula during the transition between the Archaic and Early Pre-Classic periods.

Studying the Gas Sensitivity and Magnetic Properties of Magnesium Ferrite Prepared by the Sol-Gel Route

Nickel-doped manganese–magnesium ferrite (NixMn0.25-xMg0.75Fe2O4) was prepared using the auto-combustion method. X-ray diffraction patterns showed a single ferrite spinel phase in all the prepared samples. The crystallite size ranged from 24.30 to 28.32 nm, increasing with increasing the Ni content. The porous structure of all the samples was verified with a scanning electron microscope. FE-SEM images were used to confirm the production of spherical or semi-spherical nanoparticles with little change in particle size distribution. The study revealed that the nanoparticles were small enough to behave superparamagnetically. According to the magnetic tests conducted with the VSM at room temperature, the hysteresis loop region is practically non-existent, indicating typical soft magnetic materials. In addition, the conductance responses of the magnesium ferrite nanocomposite were measured by exposing it to the oxidizing gas (NO2) at different operating temperatures. The results showed that the sensor with the nano ferrite sample of (x = 0.20) has a good sensitivity of 707.22% as well as response and recovery times.