Full Mixing Research Articles

N-succinyl chitosan-oxidized hyaluronic acid-calcium chloride hydrogel as hemostatic agent.

This study aims to develop an effective hemostatic agent in the management of irregular and deep wounds that can accelerate the hemostatic process. The background revealed the importance of rapid treatment of bleeding, with data showing a significant risk of death from blood loss. Current treatments use conventional hemostatic dressings, but they are less effective on irregular surgical wounds. Several studies have developed chitosan, hyaluronic acid, and CaCl2-based hydrogels that have hemostatic, regenerative, and antibacterial potential. However, there is still a need to develop hydrogels that are thermally stable, biocompatible, and able to accelerate the hemostatic process. This research will synthesize self-healing hydrogels by modifying the structure of chitosan and hyaluronic acid, using a certain ratio of ingredients. The research procedure was carried out with the preparation of N-succinyl chitosan (NSC) and oxidized hyaluronic acid (OHA) as the main ingredients which were then added with CaCl2 to produce self-healing injectable hydrogel. First, NSC and OHA were dissolved in phosphate buffer solution (pH = 7.4 PBS) to obtain 60 mg/mL NSC and OHA solution respectively. Calcium chloride was then dissolved in water to obtain 120 mg/mL CaCl2 solution. Then NSC-OHA-CaCl2-based hydrogels were synthesized through rapid and full solution mixing above room temperature with the composition of (1-1-0.1; 1-1-0.2; and 1-1-0.3). The targeted findings of this research are sample characterization results that explain and prove the best NSC-OHA-CaCl2 composition variation that can be used as a hemostatic agent for irregular and deep wounds. The results of the analysis obtained FTIR test data with the formation of C = N functional groups in the four samples; blood clotting time test for sample K0, K1, K2, and K3 with time 4.6, 3.33, 2.66, and 1 s; MTT assay with cell viability percentage of 77.82% for sample K0, 84.18% for sample K1, 89.30% for sample K2, and 89.50% for sample K3; hemolysis index percentage of 0.373% for sample K0, 0.555% for sample K1, 0.625% for sample K2, and 0.201% for sample K3; Viscosity test obtained data of 13 dPa s for sample K0, 15 dPa s for sample K1, 16 dPa s for sample K2, and 18 dPa. The injectability test yielded an injectability percentage of 96.84% for sample K0, 95.03% for sample K1, 94.78% dPa s for sample K2, and 94.61% for sample K3; the DSC test results of the four samples obtained a transition peak at the exothermic peak of 62.27°C for sample K0, 70.23°C for sample K1, 73.77°C for sample K2, and 74.49°C for sample K3; and the characteristic graph of the TGA test results, the weight profile of the hydrogel during heating which showed a mass change of 21.64 mg in sample K0, 16.89 mg in sample K1, 15.37 mg in sample K2, and 11.43 mg in sample K3 (°C).

Multiple intermediates in the detergent-induced fusion of lipid vesicles

Detergent-induced vesicle interactions, critical for applications including virus inactivation, varies according to the detergent type and membrane composition, but the underlying mechanistic details remain underexplored. Here, we use a lipid mixing assay based on Förster resonance energy transfer (FRET), and single-vesicle characterization approaches to identify that sub-micron-sized vesicles are induced to fuse by the non-ionic detergent Triton-X-100. We demonstrate that the process is a multi-step mechanism, characterized by discrete values of FRET efficiency between membrane-embedded fluorophores, and involves permeabilization, vesicle docking, hemi-fusion and full lipid mixing at sub-solubilizing detergent concentrations. We also dissect the kinetics of vesicle fusion to surface-tethered vesicles using a label-free quartz-crystal microbalance with dissipation monitoring approach, opening a platform for biotechnology applications. The presented strategies provide mechanistic insight into the dynamics of vesicle fusion and have implications for applications including drug delivery and sensor development where transport and manipulation of encapsulated cargo is essential.

Spongy polyelectrolyte hydrogel with Janus porous for solar-driven interfacial evaporation and sustainable seawater desalination

Janus-structured hydrogels exhibit excellent advantages in interfacial solar desalination due to their hydrophilicity and low evaporative enthalpy of evaporation, as well as the better salt resistance and mechanical properties. In this research, a simple one-step self-stratification foaming technique is employed to transform hydrogels into Janus structured for seawater desalination. Polyvinyl alcohol (PVA), poly (diallyldimethylammonium chloride) (PDADMAC), and a photothermal material (carbon black, CB) are mechanically stirred with a foaming agent (sodium dodecyl sulfate, SDS), allowing for full mixing and air incorporation, ultimately forming a sponge-like polymeric electrolyte hydrogel with abundant Janus pore structures (PANS-J). The formation of Janus pores in the hydrogel is attributed to the flocculation and high density of hydrophilic PDADMAC, causing it to sink during gelation while hydrophobic PVA floats to the surface. The Janus structure produced by this method reduces heat loss and enhances evaporation performance, achieving a pure water evaporation rate of 3.35 kg m−2 h−1 under sunlight (1 kW m−2). Moreover, quaternary ammonium ions on PDADMAC effectively separate anions and cations in saltwater, reducing salt ion diffusion into the evaporator, preventing premature pore structure blockage, and thus improving long-term evaporator performance which can improve the salt resistance and mechanical properties. By combining these advantages, Janus evaporators hold significant promise for solar-driven water purification and other applications.

Experimental Study on Influencing Factors of Mixing Solidification Strength of Marine Soft Soil

It is a common problem that the soft soil solidified strength by mixing is low. In order to search for the sensitive factors that affect the solidified strength, a certain marine soft soil is taken as an object, four influencing factors, such as solidified material and its dosage, mixing uniformity, water-cement ratio and curing environment, were selected for experimental study, the results show that: (1) the effect of the curing material and its content on the curing strength is obvious: the curing agent of HR soft clay is 183-212% of the cement curing strength, and the curing strength of the same kind of curing material with 20% is 25-44% higher than that of 15%. 2 mixing uniformity has a significant effect on the curing strength: the curing strength of slurry and soft soil after mixing for 1 minute is very different, and the average strength is only 10% of the full mixing strength. The average strength of the three-minute-agitation was 49-50% of the full-agitation strength, while the average strength of the six-minute-agitation strength was 92-93% of the full-agitation strength. 3 the effect of water-cement ratio on the curing strength is obvious: the curing strength decreases by 24-47% when the water-cement ratio is 1.0 vs 0.6, and by 75-80% when the water-cement ratio is 3.0 vs 0.6. 4 curing environment has obvious influence on curing strength: compared with standard curing condition, curing strength of low temperature curing condition is reduced by 52-57%. This study has important guiding significance for soft soil foundation treatment and solidified soil based on soft soil.

Hydrodynamic Modeling of Stratification and Mixing in a Shallow, Tropical Floodplain Lake

AbstractFloodplain lakes are widespread and ecologically important throughout tropical river systems, however data are rare that describe how temporal variations in hydrological, meteorological and optical conditions moderate stratification and mixing in these shallow lakes. Using time series measurements of meteorology and water‐column temperatures from 17 several day campaigns spanning two hydrological years in a representative Amazon floodplain lake, we calculated surface energy fluxes and thermal stratification, and applied and evaluated a 3‐dimensional hydrodynamic model. The model successfully simulated diel cycles in thermal structure characterized by buoyancy frequency, depth of the actively mixing layer, and other terms associated with the surface energy budget. Diurnal heating with strong stratification and nocturnal mixing were common; despite considerable heat loss at night, the strong stratification during the day meant that mixing only infrequently extended to the bottom at night. Simulations indicated that the diurnal thermocline up and downwelled creating lake‐wide differences in near‐surface temperatures and mixing depths. Infrequent full mixing creates conditions conducive to anoxia in these shallow lakes given their warm temperatures.

Depopulation mechanisms of atomic hydrogen in the n = 3 level following two-photon excitation by a picosecond laser

One of the major constraints of measurements of atomic hydrogen densities using two-photon absorption laser induced fluorescence in most plasma and combustion environments is the determination of fluorescence decay times ( τfluo H ), especially when using nanosecond-lasers or slow acquisition systems. Therefore, it is necessary to identify the depopulation processes of the laser excited level in order to correctly estimate τfluo H . In this study, depopulation mechanisms of atomic hydrogen excited by two-photon absorption to the n = 3 level (H(n = 3)) have been investigated using a picosecond-laser excitation and acquisition of fluorescence by a streak camera, which allowed for direct measurement of τfluo H and hence, the atomic hydrogen densities, in an H2 microwave plasma operating in the pressure range 20–300 Pa. By combining these measurements with a detailed H(n = 3) collisional radiative depopulation model, it was found that full mixing amongst the H(n = 3) sub-levels occurs in our discharge conditions, even at a pressure as low as 20 Pa. Moreover, it is also seen that the Lyman β line is only partially trapped, as its escape factor Λ31 decreases from 0.94–0.98 down to 0.58–0.86 while the measured atomic hydrogen density rises from 8±5×1019m−3 to 9±6×1020m−3 . This means that the radiative decay rate of H(n = 3) atoms varies with pressure and the classical Stern–Volmer method used to determine the quenching cross-section of excited H(n = 3) in collisions with H2 molecules, σQHn=3/H2 , is not valid for our measurements. We used two different physics-based approaches, and show that the quenching cross-section σQHn=3/H2 lies in the range 90– 106×10−20m2 , which can be averaged as 98±8×10−20m2 . This substantially improved estimation of σQHn=3/H2 obtained in this work will be useful for the accurate estimation of H(n = 3) fluorescence decay times and therefore the atomic hydrogen densities.

THREE-DIMENSIONAL CFD ANALYSIS OF TWO-STRUT ASSISTED SCRAMJET COMBUSTOR

The effectiveness of the supersonic combustor is strongly dependent on the design of the strut fuel injector. This research employs numerical analysis to investigate the combustion and flow features of the supersonic combustor, utilizing Ansys Fluent for solving the unsteady Reynolds-averaged Navier-Stokes equations along with the finite-rate/eddy-dissipation model and shear stress transport k-ω turbulence model. To boost both mixing and combustion performance, a new two-strut concept is introduced into the scramjet combustor. While previous studies have focused mostly on stable 2D two-strut setups, the current investigation aims to fill a gap by exploring an unsteady three-dimensional two-strut configuration. The validation process begins by comparing numerical methods with experimental data obtained from open literature. Following this, a comparative analysis is conducted between the mixing and overall pressure loss performance of a generic strut and the recently introduced two-strut configuration. The computational findings exhibit a satisfactory alignment with the data collected from experiments. Importantly, the inclusion of the two-strut signifies a notable enhancement in the supersonic combustor's mixing level, surpassing the performance of the original single-strut design. The mixing efficiency plot indicates that two-strut achieves full mixing earlier, covering a distance of 0.182 m, compared to the DLR strut, with a 24% boost in mixing efficiency.

Hydrodynamics and Sediment Transport at Socheongcho Ocean Research Station, Korea, in the Yellow Sea

A seasonal variability in flow and sediment flux at the Socheongcho Ocean Research Station (SORS) on the west coast of Korea in 2018 was investigated to elucidate the formation of a two-layered flow structure and changes in sediment transport during stratification. An analysis of SORS data revealed stable temperatures (5–10 °C) in deeper waters, while surface temperatures rose from 6 °C in April to a peak of 30 °C in late August, gradually declining and leading to full water column mixing by late November. This temperature variation induced stratification, influencing the development of a two-layered flow structure. In winter, a singular flow structure was observed, contrasting with the emergence of a two-layered structure as stratification progressed. In the surface layer, residual currents flowed northward in summer and southward in winter, consistent with previous studies. In deeper layers, a southward residual current persisted, irrespective of the season. Sediment flux consistently moved southward, regardless of the season or water depth, with notably higher cumulative sediment flux in the deeper layer (1300 kg·m−2s−1) compared to the surface layer (300 kg·m−2s−1). These findings diverge notably from previous studies, providing new insights into ocean currents and material transport in the Yellow Sea.

Investigation of the confinement effect on fluid-phase behavior in shale oil reservoirs during CO2 injection process

AbstractDue to the confinement effect of nanopores, the fluid-phase behavior of shale oil reservoirs is much different from that of conventional reservoirs. The accurate description of the phase change characteristics of fluid in nanopores is the basis to design development plan, production system, and EOR methods of shale oil reservoirs. In this study, molecular dynamics simulation was employed to analyze the phase behavior of single-component system and hydrocarbon–CO2 mixture system in organic nanopores. The results show that the confinement effect on the phase change pressure of the single-component system is influenced by the distribution of the electron cloud. The phase change pressure of hydrocarbons with even distribution of the electron cloud would be increased, while that of CO2 would be decreased due to the instantaneous dipole moment. In addition, as the length of carbon chains increases, the confinement effect on hydrocarbons becomes stronger. When the temperature increases, the confinement effect becomes weaker. In the hydrocarbon–CO2 mixture system, when the occurrence condition changes from bulk to the nanopore of 5 nm, the bubble point pressure decreases by 39.21–68.85%, and the critical temperature and pressure decrease by 75.98% and 7.13%, respectively. On the whole, the P–T phase envelope is shrunken under the confinement effect. CO2 is much easier to be miscible with shale oil in nanopores. Moreover, full mixing and keeping in single liquid phase of CO2–hydrocarbons mixture system can reduce the adsorption of hydrocarbons on organic pore walls. Therefore, CO2 injection could be a feasible method to enhance oil recovery in the matrix of shale oil reservoirs.

Measurements of H2O-O2 line shape parameters and the determination of the intermolecular potential for modified complex Robert-Bonamy calculations

A series of spectra, one pure H2O and four H2O-O2 mixtures, were measured for the ν2 band in the 1200–1950 cm−1 region at room temperature using a single-pass copper cell housed in the Bruker 125HR high-resolution Fourier transform spectrometer (FTS) at Jet Propulsion Laboratory (JPL). All the five spectra were fit simultaneously using a multispectrum non-linear least-squares fitting software, Labfit programme suite, which adopts a speed-dependent Voigt line shape profile using full line mixing taken into account through a relaxation matrix operation. O2-broadened half-width and O2-induced frequency shift coefficients were determined for more than 350 transitions of H2 16O. These data were then checked using the smooth variation and paring rules [Brown et al. J Mol Spectrosc. 2007;246:1-21, Ma et al. Mol Phys. 2011;109:1925-41] and 186 transitions that obey the rules with less than 3% difference were chosen. Using these selected data, Modified Complex Robert-Bonamy calculations were made to determine the intermolecular potential for the H2O-O2 collision system. Some 93 potential were investigated resulting in a final potential (potential 74) that agrees with the selected half-width measurements having an average percent difference of 0.052 and a standard deviation of 5.108% between measurement and calculations.

Seasonal Evolution of Stable Thermal Stratification in Central Area of Lake Ladoga

The complete climatic courses of the parameters of stable thermal stratification for the central part of Lake Ladoga, the largest European lake, are presented on the basis of empirical relationships, taking into account the physical processes governing water temperature variations. For the first time, the seasonal cycle of the surface water temperature, the temperature and the depth of the thermocline, and the hypolimnion temperature are calculated using the vertical profiles of the temperature obtained from the central area of Lake Ladoga. Temperature data are used for the period of in situ observations from 1897 to the present. The proposed functional forms of the temporal temperature cycle and the course of thermocline’s boundaries deepening are useful for examination and simulation of the heat vertical transport from air to water. Approximation curves for the parameters of heating and cooling periods were developed with high significant determination coefficients. Time dependencies of the climatic rates of change in water temperature and the depth of the thermocline boundaries were determined from the onset of stable stratification to its dissipation. The highest rate of water temperature change in the heating stage takes place in late June–early July, which at the water surface, is 0.32 °C/day, while in the thermocline layer, it is 0.18 °C/day. The peak velocity during the cooling stage at the surface occurs in late August–early September and is 0.14 °C/day, whereas in the thermocline, it is 0.08 °C/day and takes place between September and early October. During the period of heating, the deepening parameters of the thermocline layer do not fluctuate very much, only within the range of 0.1–0.3 m/day. During the cooling period, under the influence of free convection, rates increase drastically. The maximum rates of deepening during the period of full autumn mixing reach 1.8 m/day. When the autumn overturn occurs, the epilimnion thickness equals the bottom depth, and the bottom temperature reaches its maximum during the annual cycle. Climatic norms of the stratification parameters against which it is necessary to assess climate change are calculated.

From Local Hydration Motifs in Aqueous Acetic Acid Solutions to Macroscopic Mixing Thermodynamics: A Quantitative Connection from THz-Calorimetry.

We report the results of THz measurements (30-440 cm-1) of aqueous acetic acid solutions over the full mixing range (XAcAc = 0-1). We recorded spectroscopic observables as a function of the acetic acid concentration in the frequency range of the intermolecular stretch at 150 cm-1 and of the librational modes at 350-440 cm-1. This allowed us to unravel changes in hydrophobic and hydrophilic hydration motifs, respectively. By means of a novel THz-calorimetry approach, we quantitatively correlated these changes in local hydration motifs to excess mixing entropy and enthalpy. We find that ΔHmix is determined by both hydrophobic and hydrophilic solvation contributions. In contrast, ΔSmix is governed by hydrophobic cavity formation. Our results further suggest that acetic acid-water mixtures are systems at the edge of phase separation due to endothermic contributions from both hydrophilic and hydrophobic solvation in a large portion of the miscibility range. Our work establishes a quantitative relationship between the balance of local hydrophobic and hydrophilic solvation motifs and the macroscopic mixing thermodynamic properties.

Analysis of homogeneity and rheological properties of filling slurry during the mixing process through electrical resistance tomography

Mixing is a key process in the paste filling technology. This study utilized electrical resistance tomography and rheological experiments to examine the particle distribution and rheological properties of filling slurry at different shearing speeds, concentrations, and initial particle size distributions. The results indicated that filling slurry flow could be categorized into three states under different shearing speeds: insufficient mixing, full mixing, and excessive mixing. In combination with the rheological characteristics, the radial index and the filling slurry index could be used to measure homogenization. As the shearing speed increases, the homogeneity of the filling slurry improves, and the dynamic yield stress also changes. Increasing shearing speed has a negative impact on particle distribution as homogeneity is reached. The homogenization of the filling slurry is related to particle migration. Additionally, the mechanical response to shearing is discussed. Material and shearing conditions determine the interaction between particles.

High-frequency sensor data capture short-term variability in Fe and Mn concentrations due to hypolimnetic oxygenation and seasonal dynamics in a drinking water reservoir

The biogeochemical cycles of iron (Fe) and manganese (Mn) in lakes and reservoirs have predictable seasonal trends, largely governed by stratification dynamics and redox conditions in the hypolimnion. However, short-term (i.e., sub-weekly) trends in Fe and Mn cycling are less well-understood, as most monitoring efforts focus on longer-term (i.e., monthly to yearly) time scales. The potential for elevated Fe and Mn to degrade water quality and impact ecosystem functioning, coupled with increasing evidence for high spatiotemporal variability in other biogeochemical cycles, necessitates a closer evaluation of the short-term Fe and Mn dynamics in lakes and reservoirs. We adapted a UV-visible spectrophotometer coupled with a multiplexor pumping system and partial least squares regression (PLSR) modeling to generate high spatiotemporal resolution predictions of Fe and Mn concentrations in a drinking water reservoir (Falling Creek Reservoir, Vinton, VA, USA) equipped with a hypolimnetic oxygenation (HOx) system. We quantified hourly Fe and Mn concentrations during two transitional periods: reservoir turnover (Fall 2020) and HOx initiation (Summer 2021). Our sensor system successfully predicted mean Fe and Mn concentrations and trends, ground-truthed by grab sampling and laboratory analysis. During fall turnover, hypolimnetic Fe and Mn concentrations began to decrease more than two weeks before complete mixing of the reservoir, with rapid equalization of epilimnetic and hypolimnetic Fe and Mn concentrations in less than 48 h after full water column mixing. During the initiation of HOx in Summer 2021, Fe and Mn displayed distinctly different responses to oxygenation, as indicated by the rapid oxidation of soluble Fe but not soluble Mn. This study demonstrates that Fe and Mn concentrations are sensitive to changes in redox conditions induced by stratification and oxygenation, although their responses to these changes differ. We also show that high spatio-temporal resolution predictions of Fe and Mn can improve drinking water monitoring programs and reservoir management practices.

A Versatile Integrated Microfluidic Chip Based on Sonic Toothbrush-Assisted Mixing for Analyses of Diverse Biomolecules.

Usually, different assays and instrumentation are required for different types of targets, e.g., nucleic acids, proteins, small molecules, etc., because of significant differences in their structures and sizes. To increase efficiency and reduce costs, a desirable solution is to develop a versatile platform suitable for diverse objectives. Here, we established a versatile detection technique: first, target separation and enrichment were carried out using magnetic beads (MBs); then, different targets were converted to same barcoded DNA strands (BDs) released from gold nanoparticles; finally, sensitive detection of three different targets (miRNA-21, digoxigenin antibody, and aflatoxin B1) was achieved through exonuclease III (Exo III) cyclic cleavage-assisted signal amplification. To simplify the operation, we integrated this technique into a microfluidic chip with multiple chambers in which the requisite reagents were prestored. Just by moving the MBs through different chambers with a magnet, multiple steps can be completed. Due to the limited space in microfluidic chips, the full mixing of MBs and solution is a key point to improve reaction efficiency. The mixing can be achieved by acoustic vibration generated by a small, portable sonic toothbrush. Based on the microfluidic chip, the detection limits of the above three targets were 0.76 pM, 0.16 ng/mL, and 0.56 nM, respectively. Furthermore, miRNA-21 and Digoxigenin antibody (Dig-Ab) in serum and AFB1 in corn powder were also used to demonstrate the performance of this chip. Our versatile platform is easy to operate and is expected to develop into an automatic "sample-to-answer" device.

Dissipation and movement of soil water in artificial forest in arid oasis areas: Cognition based on stable isotopes

Large-scale construction of artificial forests in arid oasis areas plays a role in wind prevention and sand fixation, vegetation increase and landscape improvement. However, due to the extremely strong evapotranspiration in the arid areas, the construction of artificial forests may greatly increase the consumption of water resources. Therefore, it is necessary to evaluate and weigh the benefits of its ecology, landscape and water resource utilization. Based on different water isotopic data (soil water, precipitation) and related hydrometeorological data of typical poplar plantation in the middle and lower reaches of Shiyang River Basin from 2018 to 2019, this study evaluated the soil evaporation loss rate and water storage capacity of artificial forest and revealed the mechanism of soil water movement. The results showed that: (1) The average soil evaporation loss in the artificial forest was 21.30%, which was higher in spring and summer and lower in autumn and winter; (2) The soil water recharge from the artificial forest has the characteristics of preferential flow recharge, with long retention of precipitation in the soil, and full mixing of newly recharged water with original water; (3) The artificial forest increased the water storage capacity of deep soils (80–100 cm) in the oasis area, but the water consumption rate also correspondingly increased. Artificial forests must rely on water input to maintain normal growth, and its own water consumption rate and soil evaporation loss are high. Therefore, ecological, landscape, and water resource utilization benefits should be considered when constructing artificial forests in arid oasis areas where water resources are scarce.

Optimal balance of individual and collective in honeybee foraging

Purpose. Previously, we developed a minimal foraging model in a honey bee colony that is applicable to describe both the decision-making process and the phase transition between two behavioral modes of the colony, individual and collective. In this paper, we show that this model is also applicable to determine the optimal division of labor in the colony, namely, to determine the optimal proportions between different types of foragers, scouts and recruits. Model. We represent the steps in the foraging process as reactions of chemical kinetics, which leads to reaction–diffusion equations. The reaction part describes the dynamic modes of the foraging process: the recruitment of unemployed foragers to profitable food sources, that have become unprofitable as a result of their exploitation, and scouting. Diffusion describes the transfer of information in a honey bee colony. We assume almost perfect accuracy in the transmission and use of information about food sources in the colony, which is modeled by a very small diffusion coefficient of working foragers in the information space. On the contrary, the diffusion coefficient of unemployed foragers is chosen large to ensure their full mixing in the information space. This models the equal accessibility to transmitted information for all unemployed foragers in the hive. Results. We consider the profit of a colony on an exploited food source as the number of foragers working on that source, weighted by its value to the colony. It was found that with an increase in the intensity of scouting, the profit of the colony first grows, and then begins to fall, thus illustrating that there is an optimal balance of scouts and recruits, which ensures the greatest influx of food resources into the colony. Conclusion. An optimal division of labor in a honey bee colony, defining a dynamic balance between exploration and exploitation in a constantly changing environment, is essential to the survival of the colony. Considering that scouts use exclusively personal information, and recruits take advantage of social information, we can say that our model describes the optimal balance between the individual and the collective in the colony.

Taxonomic Composition of Protist Communities in the Coastal Stratified Lake Kislo-Sladkoe (Kandalaksha Bay, White Sea) Revealed by Microscopy

Lake Kislo-Sladkoe is a stratified water body partly isolated from the White Sea. Perennial meromixis in the lake irregularly alternates with mixing events. Taking into account that the protists of Arctic coastal stratified water bodies are understudied, we evaluated for the first time the vertical structure, species richness, and diversity of protists assigned to different taxonomic groups in Lake Kislo-Sladkoe using light, luminescent, and scanning electron microscopy. To test the research hypothesis that a mixing event affects the vertical stratification and species composition of protists in a stratified lake, we compared the protist communities of Lake Kislo-Sladkoe in two extremely different states: strong meromixis vs. full vertical mixing. A total of 97 morphologically distinct phototrophic, heterotrophic, and mixotrophic protists were revealed with the most diverse supertaxa SAR (59), Obazoa (9), and Excavates (14). The hidden diversity of protists (43 species) was a bit less than the active diversity (54 species). A taxonomic list and micrographs of cells for the observed protists are provided. The majority of species revealed are cosmopolitan or widespread in the northern sea waters. The vertical patterns of protist communities were absolutely different in 2018 and 2021. In July 2018, clearly distinct protist communities inhabited different layers of the lake. Bloom of cryptophyte Rhodomonas cf. baltica was detected in chemocline, whereas the maximum density of its grazers was observed in adjacent layers, mainly dinoflagellates Gymnodinium sp. and Scrippsiella trochoidea, as well as a ciliate Prorodon sp. In 2021 due to the recent mixing of lake and seawater, there were no distinct communities in the water column except the superficial 0–1 m layer of fresh water.

A neural network algorithm and its prediction model towards the full color phase mixing process of colored fibers

Aiming at the demand of color matching techniques in the spinning process, a neural network prediction model is constructed in this research study, and the gridded full color phase mixing space of colored fibers is used as the sample space. Subsequently, 30 grid points are employed as training samples, while another 30 grid points are adopted as testing samples, in which the parameters of the input, hidden, and output layers are optimized. Additionally, the neural network prediction model is constructed by training samples, and validated by testing samples. Lastly, a neural network prediction model is applied to implement the prediction of color and mixing ratios for any point within the full color phase mixing model. Through the assessment of the testing samples, the predicted results for the colors of the grid point samples showed an average color difference of 1.29 (minimum was 0.22 and maximum was 2.97); the forecasts for the mixing ratios of the colored fibers were that the range of the mean absolute error for the mixing ratios of individual samples was from 0.01% to 0.18%, and the mean absolute error for the mixing ratios of all samples was 0.21%. The experimental results indicated that the proposed neural network model has a relatively advanced prediction accuracy.

The Paraná River in the argentine plain: A review of its evolution and contemporary characteristics

This paper discusses the geological evolution of the Paraná River in Corrientes Province, located inside the Mesopotamic Argentine region, and reviews the principal geomorphological and hydro-sedimentological characteristics of this outstanding fluvial system.Active lateral migration of the Paraná River inside its large alluvial fan, which covers the north-western portion of Corrientes Province, reveals a structural control related to the separation and breakup of Gondwana. The lowlands now present in this region receive only pluvial input and constitute one of the largest wetlands in South America, the Esteros del Iberá.The best exposed geological units in Corrientes Province are the Ituzaingó Formation (Plio-Pleistocene) that is a fluvial deposit associated with evolution of the Paraná River, and the Toropí-Yupoí Formation (Pleistocene), a younger palustrine fill generated by deposition of aeolian sediment over the underlying fluvial sands.The present planform pattern of the Paraná River in Corrientes Province is anabranching with several types of bar that occupy more than 30% of the channel surface. The bed sediment is predominantly medium to fine sand with the dominant bedform being dunes, which thus also dominate its subsurface sedimentary architecture.The suspended sediment concentration of the Paraná River downstream from its confluence with the Paraguay River (its main tributary) is asymmetric across the channel width, with higher concentrations towards the west due to the much higher input of sediment from the Paraguay River, which in turn receives most of its suspended sediment from the Bermejo River. At Corrientes City, suspended sediment concentration shows extremes ranging from 1 to 616 mg L−1 on the eastern margin and from 8 to 1271 mg L−1 on the western margin. Mixing between the Paraná and Paraguay rivers flows may take more than 600 km downstream before full mixing is achieved, with the mixing processes at the junction being determined by the discharge (momentum) ratio between the two confluent rivers, topographically-driven flows and the possible influence of density driven underflows at their interface. The confluence area between the Paraná and Paraguay rivers is characterized by a large scour that is ∼30 m deep, with its deepest location being at the mouth of the Paraguay River where the channel narrows due to local bedrock control.Due to the different elevation of the Paraná River margins in the region downstream of the confluence, the contemporary floodplain is developed extensively only on the western margin. This floodplain can also be considered as proximal (flooded yearly) or distal (flooded only during extraordinary events) in its geomorphic character. Most of the headwaters of small tributaries in this part of the Paraná River basin are located in wetlands. In these wetlands, the channel beds are characterized by fine sediment consisting of silt and cohesive clays, and where the suspended sediment has a high proportion of organic matter.