Filtration Studies Research Articles

Supported Au NPs over magnetic chitosan-gelatin nanocomposite: Investigation of its catalytic activity for one-pot synthesis of tetrazoles, study of antioxidant activity and anti-uterine cancer performances

This paper reports the synthesis of a novel class of Fe3O4@CS-Gl/Au core-shell pattern nanoparticles by employing Au NPs and chitosan-gelatin composite. The biogenic synthesis was mediated by dual composite hydrogel of chitosan and gelatin as a green reducing as well as stabilizing agent under ambient conditions. Physicochemical features the so obtained nanomaterial was assessed by using FT-IR, TEM, FE-SEM, EDX, elemental mapping, VSM and XRD. Click synthesis of 5-substituted-1H-tetrazoles utilizing aryl halides was our aim in catalytic investigation. The Fe3O4@CS-Gl/Au catalyst, which is highly effective and reusable, was used to catalyze the [3+ 2]-cycloaddition of benzonitriles with NaN3, leading to the solvent-free synthesis of corresponding tetrazole derivatives at 120 °C. This method was carried out using K4[Fe(CN)6] as a non-hazardous cyanide precursor. Following a 12-hour process, the different substrates produced yields ranging from 70 to 96%. Hot filtration, leaching and reusability studies were conducted 12 times in a succession, all of which confirmed the catalyst's resilience. Furthermore, in the biological studies % cell viability of Fe3O4@CS-Gl/Au NPs was found very low against common human uterine cell lines i.e. AN3-CA and HEC-1-A, devoid of any cytotoxicity on normal cell lines like HUVEC. The best anti-uterine effect was observed against the AN3-CA cell line. For investigating the antioxidant properties of nanobio-composite, the DPPH assay was used. Fe3O4@CS-Gl/Au NPs inhibited half of the DPPH molecules in the concentration of 139 µg/mL. The antioxidant activity of the NPs is significantly related to its anti-uterine cancer potentials. Based on the above findings, the Fe3O4@CS-Gl/Au NPs could be administered in restricting diverse human cancers.

2D/2D nanohybrid of MoS2/g-C3N4 engineered polysulfone (PSF) membrane with enhanced filtration and anti-fouling performance

The rational design of 2D hybrid materials has gained substantial attention in the field of membrane-based water treatment. In this study, a hierarchical flower-like MoS2/g-C3N4 (Hf-MoCN) hybrid has been reported as a modifier for antifouling and performance enhancement of polysulfone (PSF) membranes. PSF membranes modified with 0.1, 0.3, and 0.5 wt% of Hf-MoCN were prepared by phase inversion technique. The prepared membranes were examined for their morphology, contact angle, pore size, and porosity. Further, the ultrafiltration performance and antifouling ability of the PSF/ Hf-MoCN were examined through BSA filtration studies. The contact angle dropped from 78° to 55° when 0.3 wt% of Hf-MoCN was incorporated into the PSF matrix. Moreover, the pure water and BSA fluxes of this modified membrane were improved by 2.1 and 3.6 folds, respectively, compared to the bare membrane. Besides, all Hf-MoCN modified membranes showed higher BSA rejection efficiency than the unmodified membrane. Flux recovery ratio studies showed that the membrane modified with 0.3 wt% of Hf-MoCN had better antifouling ability than the other membranes. Thus, the study showed that the incorporation of Hf-MoCN provided the membrane with a versatile transport pathway and desirable surface properties, thus improving its wettability, filtration performance and antifouling ability.

Development of an efficient, low-operating-pressure graphene oxide/polyethersulfone nanofiltration membrane for removing various water contaminants

Conventional wastewater treatment technologies tend to be high-capex, energy-intensive solutions that lack specificity for different pollution classes, and do not lend themselves to wide-scale deployment, particularly in areas of the world where industrial wastewater discharge is a significant environmental problem. In tandem, solid waste pollution arising, particularly plastic containing waste, is a persistent and serious pollution issue. This work focuses on the concept of "waste treating waste" and a multidisciplinary effort ranging from materials science and environmental management to sustainable water treatment, in addition to production of graphene oxide from mineral water waste bottles using a simple synthetic procedure that can be economically scaled up for use as a cost-effective adsorbent. Prepared graphene oxide was supported on a polyethersulfone (PES) membrane, and batch filtration studies were performed to examine its performance in the removal of methylene blue (MB) dye, Gentimicin sulphate (GMS) antibiotic, and Na2SO4 and MgSO4 salts from an aqueous solution. Operating parameters such as initial pollutant concentration, time, and solution pH were investigated and optimized using a response surface methodology (RSM) model. The results confirm the significant efficiency of the filtration process, with a maximum rejection of about 91% for MB, 93% for GMS, 67% for Na2SO4, and 64% for MgSO4, with maximum water flux of 1322, 1367, 1225, and 1059 LMH, respectively. Density functional theory calculations were considered for the GO, PES membrane, and GO/PES membrane with a GGA/PBE optimization level. Adsorption annealing locator analysis was performed for the GO/PES membrane, and the process was recalculated for MB as adsorbate. In conclusion, the adsorption effect employing produced GO/PES membrane is the most important removal, followed by Donnan exclusion and steric hindrance effect. Therefore, it is possible to build new eco-friendly membranes for nanofiltration that are affordable, stable, and effective in removing various pollutants from water systems.

Changes in filtration and capacitance properties of highly porous reservoir in underground gas storage: CT-based and geomechanical modeling

The paper presents the results of comprehensive studies of filtration and capacitance properties of highly porous reservoir rocks of the aquifer of an underground gas storage facility. The geomechanical part of the research included studying the dependence of rock permeability on the stress-strain state in the vicinity of the wells, and physical modeling of the implementation of the method of increasing the permeability of the wellbore zone - the method of directional unloading of the reservoir. The digital part of the research included computed tomography (CT)-based computer analysis of the internal structure, pore space characteristics, and filtration properties before and after the tests. According to the results of physical modeling of deformation and filtration processes, it is found that the permeability of rocks before fracture depends on the stress-strain state insignificantly, and this influence is reversible. However, when downhole pressure reaches 7-8 MPa, macrocracks in the rock begin to grow, accompanied by irreversible permeability increase. Porosity, geodesic tortuosity and permeability values were obtained based on digital studies and numerical modeling. A weak degree of transversal anisotropy of the filtration properties of rocks was detected. Based on the analysis of pore size distribution, pressure field and flow velocities, high homogeneity and connectivity of the rock pore space is shown. The absence of pronounced changes in pore space characteristics and pore permeability after non-uniform triaxial loading rocks was shown. On the basis of geometrical analysis of pore space, the reasons for weak permeability anisotropy were identified. The filtration-capacitance properties obtained from the digital analysis showed very good agreement with the results of field and laboratory measurements. The physical modeling has confirmed the efficiency of application of the directional unloading method for the reservoir under study. The necessary parameters of its application were calculated: bottomhole geometry, stage of operation, stresses and pressure drawdown value.

Correspondence on "Randomized Cross-Over Study of In-Vehicle Cabin Air Filtration, Air Pollution Exposure, and Acute Changes to Heart Rate Variability, Saliva Cortisol, and Cognitive Function".

Correspondence on "Randomized Cross-Over Study of In-Vehicle Cabin Air Filtration, Air Pollution Exposure, and Acute Changes to Heart Rate Variability, Saliva Cortisol, and Cognitive Function".

A new Schiff‐base complex of palladium nanoparticles on modified boehmite with di(pyridin‐2‐yl)methanone as a robust, reusable, and selective nanocatalyst in the C‐C coupling reaction

Boehmite is one of the stable phases of alumina that is easily available, and it also has a variety of applications. Therefore in this work, for preparation of AlOOH, Sodium hydroxide (NaOH) solutions was added to aluminum nitrate nonahydrate (Al(NO3)3.9H2O) solution. Then, the surface of AlOOH was modified with (3‐aminopropyl)triethoxysilane (APTES), due to high condensation of hydroxyl groups on its surface. Then, di(pyridin‐2‐yl)methanone (di(PM)) was immobilized on the surface of modified AlOOH toward synthesis of immobilized Schiff‐base on AlOOH (di(PM)@AlOOH) as a heterogeneous Schiff‐base ligand. Finally, a palladium complex was immobilized on its surface (Pd‐di(PM)@AlOOH) as a reusable, practical, and novel nanocatalyst. Pd‐di(PM)@AlOOH was characterized by thermogravimetric analysis (TGA) analysis, Fourier‐transform infrared spectroscopy (FT‐IR), transmission electron microscopy (TEM), scanning electron microscope (SEM) imaging, energy‐dispersive X‐ray spectroscopy (EDS) analysis, wavelength‐dispersive X‐ray spectroscopy (WDX) analysis, and inductively coupled plasma (ICP) analysis. After the characterization of Pd‐di(PM)@AlOOH, its performance was used as a highly practical, stable, retrievable, and hybrid organic–inorganic catalyst in the C‐C coupling of the Suzuki reaction. The hot filtration study of Pd‐di(PM)@AlOOH revealed that it acts heterogeneously in the Suzuki reaction. We found that this catalyst can be recycled for five runs without palladium leaching, as studied by hot filtration test and ICP analysis.

Complex of hydrodynamic studies of wells and formations at the Uzen field

The effectiveness of monitoring the development process depends on the availability of complete and high-quality information about the hydrodynamic parameters of productive formations, reservoir reservoir properties, technical condition of wells, etc. The purpose of oil, petroleum gas and reservoir water research is to obtain comprehensive data on their properties and composition, which are within the productive horizons of deposits, as a rule, are fickle. Ignoring the heterogeneity of oil properties over the area of the deposit and the lack of control over changes in physico-chemical properties during the operation of the field can lead to serious errors in predicting the parameters of field development. One of the most important sources of information is hydrodynamic (field) studies of formations and wells. The advantage of hydrodynamic methods for increasing oil recovery is that they are relatively easy to implement and do not require large economic costs. At the Uzen field, the assessment of the initial productive and filtration characteristics of the formations was carried out on the basis of studies of steady-state filtration (MSS) performed during testing of oil-saturated reservoir intervals during exploration and at the initial stage of industrial development of the field when the deposit was operating under natural depletion mode. The article presents the results of a study by the method of steady-state selections (MSS), a study by the method of pressure recovery (PRC).

The effect of the Almalyk-Akhangaran industrial zone on changes in the groundwater level of the Ahangaran river basin

This article describes the state of groundwater and surface waters in the Akhangaran River basin, around the Almalyk Mining and Metallurgical Combine (AMMC), the amount of water consumed by the population of the city of Almalyk, the amount of precipitation in the region, and the annual flow regime of existing canals in the region. Comprehensive research methods, include the analysis of scientific and technical information on the geographical, hydrogeological, geomechanical and mineralogical compositions of the Almalyk-Akhangaran industrial zone, underground and surface waters, as well as the study of all valuable components by chemical, and X-ray structural methods, and atomic emission spectroscopy. Integration and point methods are used for measuring current velocity. Basic, detailed, abbreviated and graphical methods for measuring water flow are perfomed by electric metrs. Experimental filtration studies are carried out and systems of observation wells are organized. Additionally water temperature is measured with thermocouples and water density, salt concentration and water pH are measured using ionomers.

Effect of tin spectral filtration on organ and effective dose in CT colonography and CT lung cancer screening.

Studies of tin spectral filtration have demonstrated potential in reducing radiation dose while maintaining image quality for unenhanced computed tomography (CT) scans. The extent of dose reduction, however, was commonly measured using the change in the scanner's reported CTDIvol . This method does not account for how tin filtration affects patient organ and effective dose. To investigate the effect of tin filtration on patient organ and effective dose for CT Lung Cancer Screening (LCS) and CT Colonography (CTC). A previously-developed Monte Carlo program was adapted to model a 96-row CT scanner (Somatom Force, Siemens Healthineers) with tin filtration capabilities at 100kV (100Sn) and 150kV (150Sn). The program was then validated using experimental CTDIvol measurements at all available kV (70-150kV) and tin-filtered kV options (100Sn and 150Sn). After validation, the program simulated LCS scans of the chest and CTC scan of the abdomen-pelvis for a population of 53 computational patient models from the extended cardiac-torso family. Each scan was performed using three different spectra: 120kV, 100Sn, and 150Sn. CTDIvol -normalized organ doses and DLP-normalized effective doses, commonly referred to as dose conversion factors, were compared between the different spectra. For all LCS and CTC scans, CTDIvol -normalized organ doses and DLP-normalized effective doses increased with increasing beam hardness (120kV, 100Sn, 150 Sn). For LCS, relative for 120kV, conversion factors for 100Sn produced a median increase in effective dose of 9%, with organ dose increases of 8% to lung, 5% to breast, 15% to thyroid, and 3% to skin. Conversion factors for 150Sn produced a median increase in effective dose of 20%, with organ dose increases of 16%, 18%, 26%, and 12% to these same organs, respectively. For CTC, relative for 120kV, conversion factors for 100Sn produced a median increase in effective dose of 12%, with organ dose increases of 9% to colon, 10% to liver, 11% to stomach, and 4% to skin. Conversion factors for 150Sn produced a median increase in effective dose of 21%, with organ dose increases of 16%, 17%, 19%, and 10% to these same organs, respectively. Results show that dose conversion factors are greater when using tin filtration and should be considered when evaluating tin's potential for dose reduction.

Pioneering Biofouling Resistant PES UF Membrane with MnFe2O4/g-C3N4 Nanocomposite: Insight into Mechanisms and Fouling Dynamics

The advancement of ultrafiltration (UF) membranes with minimal biofouling ability and outstanding performance is essential for effective water treatment. This study reports the synthesis of graphitic carbon nitride modified with manganese ferrite to produce MnFe2O4/g-C3N4 nanocomposite by thermal treatment and co-precipitation methods. Textural and morphological characterizations confirmed the successful deposition of MnFe2O4 particles on g-C3N4 surface. Polyethersulfone (PES) membranes were constructed containing MnFe2O4/g-C3N4 nanofiller of varying loading (0.5–3 wt.%). The MnFe2O4/g-C3N4/PES membranes executed enhanced physicochemical properties with increasing nanofiller content. Filtration and rejection experiments using pure water, humic acid (HA), and bovine serum albumin (BSA) were performed to evaluate the membranes performance. The M−2 (2 wt.% of MnFe2O4/g-C3N4) membrane revealed the maximum pure water permeability (351.4 LMH), three folds better than the bare membrane. The modified membrane displayed excellent anti-biofouling capabilities, with up to 64 % and 76 % increase in HA and BSA fluxes, respectively and high rejection values (96.5 % HA; 97.2 % BSA). The M−2 membrane demonstrated high flux recovery ratios of 91.1 % for HA and 88.8 % for BSA. The long-term filtration and pH-stability studies suggested exceptional longevity, reusability and efficiency of the membranes, under normal and harsh conditions. Overall, the MnFe2O4/g-C3N4 nanocomposite was regarded as an effective filler for materializing the permeability and anti-biofouling performance of PES-based membranes.

Methodology of experimental filtration studies (releases) from high-pressure inter-salt productive deposits of industrial lithium-bearing brines of the hydrogeological halogen-carbonate formation of the Siberian platform

It is known that all our knowledge about the industrial brines of the Siberian platform was obtained while drilling wells for oil and gas whereas targeted studies of brine-bearing horizons in deep wells for hydrocarbons are hardly conducted. One of the reasons is the high daily rate in the drilling cycle resulting in carrying out strictly limited additional works not related to drilling. Meanwhile, the geological results including the forecast, the estimation of the calculated parameters of the section productive intervals, the exploration and development methodology of deposits of industrial metal-bearing brines with abnormally high reservoir pressure directly depend on the data of the hydrodynamic studies. Today, large companies – subsurface users of the south of the Irkutsk region are tasked to determine the methodology of short-term pilot releases, which provides correct input data for reserve calculation of industrial brines of natural inter-salt carbonate fractured reservoirs of the hydrogeological halogen-carbonate formation. To determine a reliable permeability coefficient under the experimental filtration work, it is necessary to achieve a quasi-stationary filtration mode. The optimal mode is an intermittent one of brine release with a constant flow rate at the same time intervals with a continuous recording of pressure changes by the telemetry system. The results of pilot releases implemented at the Znamenskiy site of the Angara-Lena deposit of industrial lithium-bearing brines have been considered. The release methods enabling the performance of experimental filtration work in a short time, and applicable in well construction for hydrocarbon production have been proposed. Surface users can carry out the research using the proposed methodology in the case when the well bottom unexpectedly opens a brine formation with an abnormally high reservoir pressure of the fluid system. The implementation of experimental filtration work employing the described methods allows the subsoil users to substantiate the resource base of industrial brines and the elements in them including lithium, rubidium, cesium, bromine, iodine and other rare, trace elements and mineral salts.

Selective filtration of dye by tannic acid‐molybdenum disulfide composite nanofiltration membrane

AbstractDye‐selective nanofiltration membranes have great potential for chemical dye separation and purification as well as dye wastewater treatment. Two‐dimensional materials such as molybdenum disulfide (MoS2) with excellent physical and chemical properties are ideal nanofiltration membrane materials. MoS2 with few layers is used in combination with polyphenols to prepare highly selective filtration nanofiltration membranes for cationic dyes. The tannic acid (TA)‐MoS2 composite material is constructed on the surface of a micro‐porous Mixed Cellulose Ester membrane by a vacuum filtration method, and the nanofiltration membrane exhibits good flexibility and excellent film‐forming properties. The maximum filtration efficiency of TAMoS2 nanocomposite film for R6G can reach 80%, while for EY and MO, it is only 9.6% and 6.1% respectively. Filtration studies on mixtures of two different types of dyes show that the composite nanofiltration membrane has excellent separation performance. The separation characteristics and mechanism of the composite nanofilm on dyes are carefully studied, showing good selectivity for cationic dyes, which can be ascribed to the synergistic effect of non‐covalent interactions and steric hindrance. This work paves the way for the use of eco‐friendly membranes for water and wastewater treatment and provides an environmentally friendly solution for various applications.

DEVELOPMENT OF VISCOPLASTIC AND VISCOELASTIC SILICATE-CONTAINING COMPOSITIONS REINFORCED WITH RICE HUSKS FOR WATER INSULATION IN OIL WELLS

The article provides a justification for the gel-forming compositionfor well water insulation based on sodium silicate, PAA and chromiumacetate with increased strength characteristics due to the introductionof a dispersed additive — rice husk, which simultaneously exhibits viscoplasticand viscoelastic properties.Oscillation testing provided for the determination of elastic modulus (G')and loss (G"), linear measurement range and quantitative determination ofviscoelastic and viscoplastic properties of hydrogel based on the interpretationof the results of creep and recovery studies using mechanical modelsof Maxwell, Kelvin-Voigt and Burgers, previously successfully used in thediscussion of the behavior of polymer systems.It is established that when approximating experimental measurements, onelink of the Kelvin-Voigt model is not enough, therefore, the Burgers computationalmodel is recommended, which corresponds to two relaxationtimes of a viscoelastic medium due to two types of crosslinking: ionic (dueto the bonding of the chromium ion with the polymer) and flocculation(due to the flocculation of dispersed rice husk particles by polymer macromolecules).Filtration studies performed on the model of an ideal crack with differentopenings (from 0.01 to 0.1 cm) have established that the introduction ofrice husk into the hydrogel composition leads to an increase in its strengthcharacteristics and resistance to mechanical destruction.In the case of filtration through a 0.1 cm slit, there was no noticeable differencein the rheological behavior of the hydrogel with and without theaddition of rice husk, except for some strengthening of the gel during filtrationat low shear rates.A mechanism responsible for the behavior of a hydrogel with this dispersedadditive in cracks of various openings is proposed.The application of the developed hydrogel composition is promising inreal fractured reservoirs, through which water flows to the well and, as aconsequence, its flooding.

A comprehensive review of the use of Sodium Chloride (NaCl) in the development of the COVID-19 vaccine and medical applications

Salt, specifically sodium chloride (NaCl), is the most common and essential salt used in chemical industries, food production and medical applications. This review extensively looked into the use of salt in medical applications and the development of vaccines, including the recently developed SARS-CoV-2 vaccine. This review also discussed several salt-producing systems to further understand the source of salt. This study focused on several main fields of medical use of salt: saline solution content, respiratory filtration, hyponatremia, ophthalmology, dermatology, and vaccine development studies. Several studies identified that NaCl could deactivate viruses as observed, NaCl is part of the COVID-19 vaccine excipient for Pfizer-BioNTech and AstraZeneca. Further applications of sodium chloride should be explored due to its various advantages in the medical field.

Thin-film nanocomposite membranes for efficient removal of emerging pharmaceutical organic contaminants from water

Membranes are receiving significant attention to remove emerging organic micropollutants (OMPs) from wastewater and natural water sources. Herein, we report the facile preparation of a novel thin-film nanocomposite (TFN) membrane with high permeability and efficient removal of OMPs. ZnO nanoparticles were first synthesized using the co-precipitation method and functionalized with N1-(3-Trimethoxysilylpropyl)diethylenetriamine to make the surface rich with amine groups and then synthesized nanomaterials were covalently cross-linked into the active layer during the interfacial polymerization (IP) process. The performance of the membranes containing the cross-linked ZnO was significantly better than the non-cross-linked ZnO NPs containing membranes. Adding multiple hydrophilic groups and entities on the surface significantly decreased the contact angle (from ∼60° to 20°). SEM images confirmed the uniform presence and homogeneous distribution of the functionalized NPs throughout the entire membrane surface. Zeta potential measurements showed the modified membranes have a lower negative charge than the pristine membranes. Filtration studies revealed a significant increase in permeability ascribed to the creation of nanochannels in the membrane's active layer. The modified membranes outperformed commercial NF membranes in removing four common OMPs with rejection efficiencies of ∼30%, 64%, 60%, and 70% for Sulfamethoxazole, Amitriptyline, Omeprazole, and Loperamide HCl, respectively. The higher removal efficiency was attributed to the weakened hydrophobic interactions due to the presence of hydrophilic moieties and a stronger size exclusion effect. Moreover, the modified membranes showed high resistance to bacterial adhesion in static conditions.

Comparative Study of Email Spam Filtration Using Machine Leaning Algorithms

Comparative Study of Email Spam Filtration Using Machine Leaning Algorithms

Lead-imprinted polyvinylidene fluoride membrane for selective removal of lead from contaminated water: material fabrication, filtration application, and mechanism study.

The drinking water has become contaminated with lead in many countries across the world. In this study, a novel lead-imprinted polyvinylidene fluoride (PVDF) membrane was successfully fabricated for selective decontamination of lead from water. First of all, the membrane fabrication process was explored and optimized. The physical and chemical properties were then studied for a better understanding of the features of the membrane. The performance of lead removal by the adsorptive membrane was evaluated by systematic batch adsorption experiments, including pH effect, kinetics, isotherm, selectivity, and regeneration studies. The results indicated that the adsorptive membrane showed a high adsorption capacity of 40.59 mg Pb/g at the optimal pH of 5.5, fast kinetics of 2 h, high selectivity towards lead, and outstanding regeneration performance. The Langmuir equation fitted the isotherm better than the Freundlich equation, while the pseudo-second-order model and pore diffusion model well described the kinetics. The adsorptive membrane showed high selectivity towards lead in the lead/zinc binary solution. In the continuous filtration study, a small piece of adsorptive membrane could treat 3.75 L of lead solution. The XPS studies revealed that the lead uptake was mainly due to the complex reaction between lead and carboxyl and hydroxyl in the membrane.

MODELLING OF A THREE-DISPERSED SUSPENSION FILTRATION

The injection method of soil stabilization is one of the methods to improve the soil base during the road construction. This method consists in the introduction of special compounds into the ground with the help of special equipment. Such compositions, as a rule, are solutions of polymers or cement, which harden, forming a solid base. The advantages of the injection method of soil stabilization for roads include rapid completion of work, minimal environmental impact, the possibility of application in difficult geological conditions, as well as strengthening the soil base at great depth. Injection solutions penetrate into microcracks and micropores of soils, forming a deposition. The study of liquid filtration in a porous soil system is of great practical importance. The paper considers the filtration of liquid in a porous medium with three types of particles. In the considered problem, each of the three types of suspension particles is characterized by its linear filtration function. It determines the size-exclusion particle capture mechanism, in which particles whose diameter exceeds the size of the pores get stuck in them, the rest pass through them unhindered. Numerical solutions are obtained for the concentrations of suspended particles of three types, as well as the total deposition. Depending on the initial parameters of the problem, the concentrations of suspended particles are either monotonic functions or non-monotonic, reaching the maximum value. In this paper, asymptotic solutions are constructed for the concentrations of suspended and retained particles near the concentration front, which are compared with numerical ones. The solution is obtained at infinity using a traveling wave.

Study of filtration, digestion and absorption of Chlorella pyrenoidosa by juvenile Chinese mitten crab (Eriocheir sinensis)

While previous studies have reported that the zoea and megalopa stages of Eriocheir sinensis can filter phytoplankton in water bodies, it remains unclear whether juvenile crab (E. sinensis) possess the same ability. The objective of this study was to investigate whether juvenile crabs (average body weight 9.51 ± 1.57 g) can filter and absorb phytoplankton. Firstly, stomach and intestinal contents of juvenile crabs were analyzed, and their filter-feeding ability was tested under different pellet feed ratios using a blood cell counter. It was found that juvenile crabs cultured in Chlorella pyrenoidosa suspension contained large quantities of the algae in their stomach and intestinal contents compared to the control group, which were cultured with no C. pyrenoidosa. Additionally, the filtration rate of juvenile crabs to C. pyrenoidosa decreased with the increase of pellet feed proportion. Finally, the ability of juvenile crab to digest and absorb C. pyrenoidosa was studied through 15N stable isotope labeling technology. The δ15N values in muscle and intestinal tissue of group filtered with 15N labeled C. pyrenoidosa were significantly higher than group filtered with unlabeled C. pyrenoidosa and control group. The results indicated that juvenile crab could filter, digest and absorb C. pyrenoidosa, expanding our understanding of the feeding ecology of this species. This has significant implications for the ecological culture of E. sinensis and the potential for sustainable aquaculture practices.

Influence of factors on filtration regime of an earth dam under headwater drawdown

Introduction. As the statistics of observations of groundwater retaining structures shows, one of the most significant factors of emergencies in these structures is the occurrence of filtration deformations in the dam body. This often results in the appearance of moves of concentrated filtration. The occurrence of these phenomena can be provoked by a rapid decrease of the headwater level known as reservoir drawdown. It can be caused either by the technological requirements of the operation of the hydraulic unit or by the occurrence of an emergency situation. Modern design standards require mandatory consideration of the case of rapid drawdown with an assessment of the filtration regime and stability of the structure.
 
 Materials and methods. The results of numerical studies of unsteady filtration in a homogeneous earth dam under reservoir drawdown are considered. Numerical studies were carried out on the basis of the finite element method using the PRAXIS software package. Test calculations were carried out, which showed the reliability of the results obtained. The influence of the soil filtration coefficient of the dam, the rate of drawdown and the slope of the structure on the change in the position of the depression curve and the value of the maximum pressure gradient is analyzed.
 
 Results. For the considered variants of earth dams with different characteristics, the parameters of the filtration flow are obtained when the headwater level changes: the position of the depression curve and the values of the maximum pressure gradients. An assessment of the possibility of occurrence of filtration deformations of soils of the upper prism of the dam is given.
 
 Conclusions. The use of the PLAXIS software package for solving problems of unsteady filtration under reservoir level changes allows to obtain reliable results that are well comparable with the results of other proven methods. At certain rates of runoff for soils of different permeability in the upper prism of an earth dam, large values of pressure gradients exceeding critical values may occur. This indicates the necessity to control the process of drawdown and the use of antifiltration measures.