Dry Mixtures Research Articles

Effect of K/Na ratio on adsorption of sweetened gas in dehydration packed bed adsorber: A Monte Carlo simulation study of single and multicomponent gas mixture

The input feed of natural gas dehydration units often contains significant quantities of mercaptan. To effectively separate water from the sweet gas stream, it is crucial to select an appropriate molecular sieve. Mercaptan adsorption can cause issues in later stages of the process. In this research, the Grand Canonical Monte Carlo (GCMC) method was employed to investigate the adsorption behavior of methane, ethane, water, methyl mercaptan, and carbonyl sulfide as both single and multicomponent gas mixtures on LTA zeolite with varying K/Na ratios. The obtained data were modeled using the Langmuir and Sips models, with the Sips model exhibiting better agreement with the simulation results. Gas adsorption simulations were conducted across temperatures of 323 K, 313 K, 303 K, and 333 K, a pressure range of 1–70 bar. The findings indicate that increasing temperature diminishes adsorption on LTA zeolite, while increasing pressure has an incremental effect on adsorption. Adsorption studies were performed for both wet and dry gas mixtures. A rise in the number of potassium ions within the zeolite structure resulted in decreased component adsorption, potentially due to the reduction in zeolite cavity size. The results emphasize that the sodium-to-potassium ratio plays a crucial role in mercaptan adsorption or depletion within the packed bed tower. For a gas mixture, it is not recommended to utilize LTA zeolite with a potassium content lower than 55% for gas adsorption due to its propensity to adsorb mercaptan.

Correlation of Two Biodegradability Indices of PLA-Based Polymers under Thermophilic Aerobic Laboratory Conditions

The biodegradation of bioplastics is a topic of interest worldwide. This work aims to measure the biodegradability of five polylactic acid (PLA)-based bioplastics under aerobic, thermophilic laboratory conditions and correlate their weight loss with their CO2 generation over a 3-month period, as both are considered indexes of biodegradation. The experimental design was based on the simulation of composting conditions by placing the bioplastic samples mixed with compost in sealed glass vessels that were regularly opened. The results showed significant variability in biodegradation, as dry weight losses ranged from 15.1–99.7%, while CO2 generation ranged from 9.2–14.9 g C–CO2/kg dry mixture (bioplastic + inoculum) depending on the sample. Moreover, no significant correlation between the weight losses and the gross CO2 production was calculated (p = 0.656), indicating the importance of carefully selecting the methods to assess biodegradation potential. This lack of correlation also reveals that different pathways are likely involved during the biodegradation of bioplastics and that the weight loss alone cannot indicate the conversion of solid C to CO2. This work proposes the need to develop an optimal degradation index for bioplastics that would provide a better understanding of their biodegradability in composting reactors. This index should combine dry weight loss and CO2 generation to assess the biodegradation of bioplastics with high confidence.

Multi-dimensional preparation of Thymus quinquecostatus Celak. by normal-phase flash chromatography coupled to counter-current chromatography

In this study, a multi-dimensional chromatography system was developed by integrating normal-phase flash chromatography and counter-current chromatography to isolate flavonoids, phenylpropanoids, and thymol from the aerial parts of Thymus quinquecostatus Celak. In the online multi-dimensional switching system, a normal-phase flash chromatograph packed with 1.2 g of dry homogeneous silica gel mixture (containing 600 mg of methanol extract) was connected to counter-current chromatography via a six-port valve. Two two-dimensional separations were performed using n-heptane-ethyl acetate-methanol-water (6:4:6:4, v/v) and ethyl acetate-water solvent systems sequentially to separate the constituents of Thymus quinquecostatus Celak. The upper phase of the former solvent system was utilized as both elution solvent for flash chromatography and the stationary phase for counter-current chromatography, while the lower phase of the latter solvent system containing 10 mM trifluoroacetic acid was employed as elution solvent for flash chromatography and one mobile phase in pH gradient counter-current chromatography. Thymol (7) and xanthomicrol (8), two hydrophobic ingredients, were purified in the initial two-dimensional separation. The subsequent two-dimensional separation yielded six hydrophilic compounds, namely dihydrokaempferol-7-O-D-glucopyranoside (1), lithospermic acid (2), luteolin-7-O-glucuronide (3), rosmarinic acid (4), messerschmidin (5) and apigenin-7-O-D-glucuronide (6). This study represents the first documented use of online multi-dimensional normal-phase flash chromatography coupled to counter-current chromatography for separating constituents from Thymus quinquecostatus Celak.

THE EFFECT OF THE TYPE AND CONTENT OF CARBONATES ON THE CHARACTERISTICS OF POROSITY OF CERAMIC MEMBRANES

The main issue considered in the work is the creation of a matrix for ceramic membranes, which would be distinguished by low cost and high porosity. In order to reduce the cost of ceramic membranes, a widespread approach was chosen, which is powerfully used by many researchers, namely the use of natural minerals - kaolin and saponite - as the main components of the matrix. Carbonates were used as pore generating agents to achieve the required porosity value. Three series of ceramic membranes (CM) differing in chemical composition were synthesized in the work: KP1, KP2, and KP3 series. The main composition of CM includes: kaolin, saponite, sodium silicate and carbonates. The effect of the type and amount of carbonates (CaCO3, NH4HCO3, (NH4)2CO3) as pore generating agents on the formation of the porous structure of the samples was studied. The type and content of carbonates varied in different samples from 8 wt% up to 40 wt%. The dry pressing method using pressure equivalent to 8 tons and 15 tons was used to form ceramic membranes. The main parameters by which the properties of ceramic membranes were evaluated: water absorption, total and open porosity. Standard methods were used to determine these parameters for synthesized samples. The chemical composition of the dry mixture of the ceramic membrane, for which the porosity is the maximum in the series of manufactured samples, was established. It was established that the addition of calcium carbonate components to the dry mixture increases the porosity of ceramic membranes and water absorption. The chemical composition of a ceramic membrane sample with the best indicators of total and open porosity in the KP2 series is given. The chemical and phase composition of samples of the KP2 series, as well as their structural and adsorption characteristics, were investigated by X-ray fluorescence and diffraction methods of analysis and low-temperature nitrogen adsorption-desorption. The effect of the addition of silicon carbide on the characteristics of the porosity of the samples was determined.

ОТБОР ПРОБ ПРИ ОЦЕНКЕ КАЧЕСТВА СМЕШИВАНИЯ

The improvement of the technological process of preparing dry loose feed mixtures is associated with an increase in the structure of feed rations for farm animals in the conditions of farms. It is noted that an increase in the digestibility and palatability of feed, a decrease in the specific energy consumption for the production of feed mixtures depends on the quality of their mixing. The methodological basis of the work was the results of studies of recent years by leading domestic scientists in the field of improving the technological processes for preparing feed mixtures, design and operating parameters of mixers. The analysis of sampling methods is given: periodic for batch mixers; cumulative, allowing to obtain a generalized sample, more representative of the mixing process, also applicable to the study of batch mixers; using special devices - samplers to obtain the most accurate samples. The importance of selecting a control component oriented to the functional features of the mixers, regardless of the sampling method used, is highlighted when monitoring the homogeneity of the mixture. The analysis of existing studies showed a wide range of control components, methods of sampling and separation of components in the study of the mixing process by machines of various designs and principles of operation. The analysis of the works showed that in order to reduce the time spent on isolating the control component and ensure the reliability of the studies, it is necessary to take into account the nature of the mixed cultures. When choosing seeds of sweet clover, clover, millet as control components, a sample mass of 5 grams is sufficient; seeds of beets, buckwheat, wheat and barley, a sample mass of 100 grams is sufficient; seeds of peas, corn, a sample mass of 300 grams is sufficient. A sieve classifier with optimal selection of the mixture with the possibility of separating in sieve or sieve analysis is noted as the most applicable for the isolation of the control component. It is recommended to focus on the method of periodic sampling when examining batch mixers. The cumulative sampling method using samplers is recommended for investigating the performance of continuous mixers and evaluating the overall quality of mixing in batch mixers.

Compound Feed Industry: benchmarks, potential opportunities

Relevance the main component for production of feed products in livestock industry is feed grain. The provision of the republic with grain crops, as well as exports, are associated with their use for fodder purposes, consumption traditionally accounts for more than half of the domestic consumption of their processed products. The goal is to study the problems and prospects of the feed industry, which determines the effective functioning of the entire grain market, supplying agricultural enterprises and farms with necessary and high-quality feed. This was largely facilitated by the intensive development of food industry and grain farming, which became the main suppliers of raw materials for feed mills. Methods – comparative, systemic, statistical analysis, logical generalization. Results – the authors note that in the structure of feed raw materials, main share falls on barley, oats, wheat, while the share of corn and legumes has decreased. Based on the available livestock, the standard needs of animal husbandry are not provided. The export orientation of domestic grain production is primarily aimed at the needs of the world market, at the same time, domestic needs are satisfied on a residual basis. Rational use of cereals will improve the quality and competitiveness of animal products. The opportunities created by «National Company «Food Contract Corporation» JSC for the sale of grain fodder to poultry farms enhance holding back the prices for finished food products by concluding agreements with manufacturers and retail chains. Conclusions – it is obvious that the basis for the transfer of the livestock complex to industrial resource-saving technologies is the creation of a solid forage base. Without a balanced feeding of animals in terms of protein and vitamin-amino acid composition, other measures will not have the expected result. Emphasis is placed on the need to increase the capacity of large enterprises to provide feed products on industrial scale and manufacture dry nutritious feed mixtures in feed mills and factories based on their own raw materials, mineral and vitamin supplements for grain processing and livestock farms.

ПОРІВНЯЛЬНИЙ АНАЛІЗ МЕТОДИК ВИМІРЮВАННЯ АДГЕЗІЇ РЕМОНТНИХ РОЗЧИНІВ З СУХИХ БУДІВЕЛЬНИХ СУМІШЕЙ ДО БЕТОННИХ ПОВЕРХОНЬ

The article provides a general assessment of the adhesion strength indicators of polymer-cement repair composites to the concrete base and determination of the degree of repeatability of test results when changing the methods of its measurement in accordance with Ukrainian and European standards. During experimental studies, data were obtained on the adhesive strength indicators of the same cement samples of repair mortars based on dry building mixtures for the repair and restoration of concrete and reinforced concrete structures and buildings under equal conditions using different measurement methods, a distribution was obtained by the received classes of repair composites, taking into account the requirements of both standards according to the indicator of adhesive strength. The obtained data show that according to the measurement method according to the Ukrainian standard, the vast majority of the examined samples of repair mortars based on dry construction mixtures showed similar measurement results, which indicates a high repeatability of the results of the measurement method. Also, a high percentage of adhesion loss according to the AF-S and CF-S classes and the number of structural classes among the studied composites remain among all the studied samples. The European measurement method on the same samples and reference concrete slabs showed a significantly higher number of samples with a deviation from the average adhesion index, a lower number of samples with a loss of adhesion according to the AF-S and CF-S classes, a lower number of structural classes of repair composites and, in general, has a significantly lower repeatability of measurement results. It has been established that some of the repair composites, which according to the requirements of the Ukrainian standard correspond to the highest structural class of the repair material РМ1 based solely on the adhesion index, can be classified only as materials of the R3 class according to the requirements of the European.

Carbon capture from humid gases using alkaline-promoted polypyrrole by a vacuum swing adsorption process

Post-combustion carbon capture from humid flue gas is one of the urgent research projects for achieving the target of carbon neutrality in near future. Nitrogen-containing polymers are considered as a promising adsorbent for carbon capture in flue gases due to their potential water resistance. Here, two-step synthesis of alkaline-promoted polypyrrole (AP-PPy) with water resistance was investigated as an adsorption material for carbon capture and separation. It was found from chemical and physical analysis that the alkaline-promoted sample kept the similar morphological structure as the pristine polypyrrole but possessed more amino groups. The adsorption of single component gases revealed that the adsorption amounts of CO2, CH4, and N2 were 1.31, 0.28 and 0.065 mmol/g at 303 K respectively, among which the CO2 uptake was 80% higher compared with the original polypyrrole. The breakthrough point of AP-PPy in moisture is comparable to that of dry mixture, but the dynamic CO2 adsorption capacity is calculated to be larger than that of dry condition. A single-bed three-step vacuum swing adsorption cycling device was constructed in the laboratory and the effect of adsorption time, vacuum pressure and feed flowrate on product purity and recovery were explored with over 50 cycles in each condition to ensure cyclic steady adsorption, thereby also verifying the recyclability of AP-PPy. The excellent CO2 adsorption and separation properties demonstrated that AP-PPy can be a promising material for post combustion carbon capture.

REGULATION OF THE PROPERTIES OF SAND-CLAY MOLDING MIXTURES BY SODIUM PHOSPHATE ADDITIONS

Purpose. Study of the effect of sodium phosphate additives on the properties of a reversible sand-clay mixture in the green and dry state to improve the quality of castings from iron-carbon and aluminum alloys.
 Research methods. A reversible molding mixture based on quartz sand and kaolin clay was used. The effect of three additives (sodium tripolyphosphate, sodium hexametaphosphate, sodium pyrophosphate) in amounts from 0.5 to 2.0% was studied. Properties of mixture were determined using standard methods: clay component content, strength, gas permeability, crumbleness, flowability, formability, packing.
 Results. Effective additives have been studied to ensure the possibility of multiple use of reversible molding sand-clay mixtures. Special attention is paid to the regulation of the properties of the mixture in the dry state, since this issue has been much less researched today. For this purpose, sodium phosphates, which are produced by the chemical industry in sufficient quantities, were used for the first time. As materials that affect the properties of the mixture as a whole, they have not been considered before.
 Scientific novelty. For the first time, the positive effect of sodium phosphate additives on the physical and mechanical properties such as strength and crumbleness of reversible sand-clay mixtures was established. This effect is manifested in the fact that additives contribute to a slight improvement of properties of the green mixture and a very significant improvement of these properties of the dry mixture. There is practically no effect on important technological properties (flowability, formability, packing).
 Practical value. Based on the results of the experiments, it is recommended to use sodium tripolyphosphate or hexametaphosphate additives in the amount of 0.5 to 1.0 % to significantly improve the properties of dry sand-clay foundry molds. The use of these additives eliminates the appearance of surface defects in cast parts from aluminum and iron-carbon alloys.

Repeated impact resistance of steel fibre-reinforced dry UHPC: Effects of fibre length, mixing method, fly ash content and crumb rubber

Dry concrete exhibits significantly different mechanical properties and failure patterns under dynamic loads from those under static conditions. Considering the practical applications of dry concrete, the flexural impact load renders its units/structures susceptible to unpredictable damage or even failure. In this study, the modified low-velocity drop-weight impact test was conducted on steel fibre-reinforced dry UHPC (FR-DUHPC) beam samples to simulate the frequent and multiple impact loads. The effects of steel fibre length, mixing method, fly ash content and crumb rubber addition on the impact resistance of FR-DUHPC were evaluated based on dynamic responses. Weibull distribution was then conducted to analyse the failure hit number of concrete samples in consideration of the large value variation. Test results indicated that the flexural impact performance was markedly improved with longer steel fibres, but deteriorated with increased fly ash content (especially at early ages) and considerably degraded with the inclusion of rubber aggregate. Hybrid medium/long fibre reinforcement was proposed for DUHPC that were mainly subjected to impact loads during service, while the fly ash content utilized to partially replace cement was not recommended to exceed 40%. Rubber aggregate was not proposed to be added to dry concrete mixtures since the impact load would greatly accentuate the initial matrix defects caused by the weak bonding. Additionally, the two-parameter Weibull distribution was verified to be a desirable statistical method for analysing the failure blow number of FR-DUHPC under repeated low-speed drop-weight impacts. The impact energy for the practical structural design could be preliminarily computed utilizing the derived Weibull parameters at different levels of reliability.

Effects of adult-diet modifications on sexual maturation rate, body weight, and quantity of sperm transfer by male Mexican fruit fly (Diptera: Tephritidae).

Mass-reared sterile Mexican fruit flies (Anastrepha ludens [Loew]) are released along the US-Mexico border to control fruit fly damage and spread. It is more cost effective for the mass rearing program if males mature at a younger age because they can be held for a shorter time at the facility before release. In this study, adult male Mexican fruit fly diets were tested to determine if the current diet used at the mass rearing facility promotes younger mating and optimal sperm transfer compared to other diet formulations. Hydrolyzed yeast presentation methods were examined: an agar-free dry mixture of yeast and sugar (Y+S), yeast embedded in the diet during the agar boiling process (current method used) and sifted dry on the ager gel surface. Methoprene, a juvenile hormone analog was also tested as a supplement to agar gel diets with and without yeast. A greater proportion of males fed Y+S mated 1 day earlier than males fed other diets. Male mating age and diet did not significantly affect the quantity of sperm transferred; however, a non-significantly higher percentage of males fed diets with embedded yeast transferred enough sperm to fill all 3 spermathecae. The results suggest that the current diet used is optimal for mass-rearing the flies and that yeast presentation method has a significant effect on A. ludens male mating age but not on the quantity of sperm transferred to females.

Parameters determination of dry building mixtures based on gips and polimeric additives

Purpose. The properties determination of gypsum raw materials for the production dry building mixtures based on them.To investigate the modifier additives effect on the properties of dry construction mixtures, to establish the expediency of their use and rational quantity. The methods. Laboratory studies were performed in accordance with the current regulatory documents, which regulate the study of building composites as such and raw materials and finished products, which were considered in the submitted work. A number of experimental investigations of many-component compositions have been carried out from the point of view of their rheological and physical-mechanical properties. Additives-modifiers were considered as components that may be influencing the necessary effect on the finished material. Findings. In the production of dry building mixtures based on gypsum, it is necessary to add additives of different spectrum of action to the main composition –thickeners; additives that increase adhesion strength to the treated surface; components that prevent the formation of cracks; regulators of the gypsum hardening or even those that accelerate the hardening of the building mixture.It was determined raw materials and conditions, when using of additives-modifiers is appropriate. An analysis of the components has been made, which seems to be the widest choice with the point of view with the current technology. The most rational dosing of the all components is also given, which may have influence into the properties of the working mixtures and the ready-made budding cover. The originality. The relationship between the combination of components of the gypsum-based dry building mixture has been established, which allows to increase the interval between the beginning and end of the hardening of the gypsum-based building mortar by no less than 30 minutes. Practical implementation. The data obtained of laboratory researches allow to prepare dry building mixtures based on gypsum, that duration is predicted in hours according to all the technological operations of plastering works. It will increase the efficiency of works and improve the comfort of masters.

Water Retention Characteristics of Superabsorbent Polymers (SAPs) Used as Soil Amendments

Superabsorbent polymers (SAPs) are used as a soil amendment for retaining water, but suitable methods for the application of SAPs have not yet been developed. Here, we characterized a variety of soil–SAP mixtures prepared using four different types of SAP in terms of their water absorption and release characteristics. The teabag method was applied to characterize the soil–SAP mixtures, except for measurements of the matric potential. The results showed that the variations in water absorbency among the four SAPs in isolation became insignificant when they were mixed with sandy soils. The rates of water released from the soil–SAP mixtures under heated conditions were mitigated with decreasing water content, which prolonged the time until desiccation of the mixtures. The water absorbency of the SAPs significantly decreased in salt solutions (KCl and CaCl2), but their absorbency mostly recovered following immersion in tap water. The soil–dry SAP mixtures retained a larger amount of water than the soil–gel SAP mixtures. Swollen SAPs predominantly retained water in the range of −0.98 to −3.92 kPa, suggesting that SAP induces a transition from gravitational water to readily plant-available water by swelling itself. SAPs barely increased the amount of plant-available water in a potential range of −3.92 to −98.1 kPa, but significantly increased the soil water at <−98.1 kPa. The soil water content increased with an increasing SAP application rate, whereas the proportion of plant-available water declined. Our findings indicated that the performance of SAPs depends on the pore space and a saline environment in the soil and that low SAP application rates are suitable for maximizing the water available to plants in sandy soils.

Dry Electrode Manufacturing in a Calender: The Role of Powder Premixing for Electrode Quality and Electrochemical Performance

The dry manufacturing of battery electrodes has the potential to significantly reduce costs and the environmental impact of battery production but deteriorates the electrode quality due to drawbacks in the processability of the materials. By varying the mixing intensity of the powder mixtures, this work investigates the impact of blend homogeneity on the flow properties and the processability of the dry mixtures. Furthermore, the electrochemical performance of dry laminated electrodes made of LiNi0.6Mn0.2Co0.2O2 is investigated with respect to their initial mixture homogeneities and compared to slurry-based electrodes. An improvement of the powder flowability is observed for mixtures with a homogeneously distributed PVDF binder, which acts as a temporary lubricant in dry electrode manufacturing due to its ability to shear, resulting also in filament formation. Capacity and rate performance of electrodes made of homogeneous mixtures are the highest with 169 mAh/g at C/20 and 70 mAh/g at 3C compared to 169 and 49 mAh/g for the slurry-based electrodes, respectively. Cyclic voltammetry indicates lower overpotentials for incompletely homogenized electrodes due to the existence of carbon black aggregates that establish better long-range conductivity. Overall, electrodes from highly homogenized powders show the best electrochemical performance in terms of C-rate capability due to their favorable electrode thickness and porosity resulting from better processability in combination with a sufficiently distributed carbon binder domain.

Study and application of the shift-temperature of heating fluid for zeotropic mixtures in organic Rankine cycle

The theoretical formulations of the shift-temperature of the heating fluid for zeotropic mixtures (Tshift) were derived when the pinch point was located at the evaporating bubble point and the working fluid inlet of the evaporator, respectively, which were applicable to dry, wet, and isentropic zeotropic mixtures. Tshift was corrected by the impact factor analysis and calculated exactly using the Dragonfly algorithm. The optimal zeotropic mixture was matched by comparing the heat source temperature(Tg, in) and Tshift. The results indicate that Tshift is a property of every zeotropic mixture and is related to the critical temperature, the evaporation bubble point temperature, and the condensation dew point temperature. When the pinch point is at the evaporation bubble point, the zeotropic mixture with Tshift lower than Tg, in is selected and then combined with the thermal efficiency for a comprehensive evaluation. When the pinch point is at the working fluid inlet of the evaporator, Tshift is also affected by the pinch point temperature difference and the temperature glide of the condensation process, Tshift is significantly lower than Tg, in, all zeotropic mixtures are applied. Among the matched zeotropic mixtures, R227ea/R22 with the lowest Tshift has the best thermal performance in the ORC system.

Model of Feed Preparation in the Conditions of Small Farms

. A model of fodder preparation for small farms is proposed. The main ways of increasing the efficiency of fodder production have been identified. Equipment has been developed and proposed, from which technological schemes for the production of dry and wet mixtures of concentrated feed, fermented feed in the conditions of small farms are made. The effectiveness of the use of this equipment is shown.

Solvent-free lithium iron phosphate cathode fabrication with fibrillation of polytetrafluoroethylene

Fabricating electrode for lithium-ion batteries (LiBs) with solvent-free (SF) procedure can save energy and improve electrochemical performance simultaneously. Polymer fibrillation is one of the most promising SF procedures due to its feasibility for upscale production. The hardness of lithium iron phosphate (LFP) impedes its SF fabrication with polytetrafluoroethylene (PTFE) fibrillation. In this study, we successfully expanded PTFE fibrillation for SF LFP electrode fabrication with the help of carbon nanotubes (CNTs). CNTs increase the conductivity of electrode, and act as matrix for LFP particles to ensure relative displacement to further fibrillate PTFE to form self-supporting electrode film when the dry mixture was hot rolled. The SF LFP/hard carbon full cells were fabricated and demonstrated comparable electrochemical performance to slurry casting (SC) fabricated LFP electrode. The initial coulombic efficiency (ICE) of full cell increased to more than 95% after prelithiation.

Assessment of concrete road paving blocks with coal bottom ash: Physical and mechanical characterization

Urban road pavements made by interlocking concrete paving blocks (CPB) manufactured using industrial by-products are an improving sustainability goal for light traffic areas. Through physical and mechanical characterization, this paper aims to assess CPB with coarse coal bottom ash (CBA), a novelty in aggregate grading terms. Then, eight dry concrete mixtures (two with CBA and six without CBA) were designed with two water/cement ratios (0.63 and 0.73) to produce rectangular CPB 20 cm × 10 cm × 8 cm (length × width × thickness) by a vibro-press machine. The correlation was established between the CPB compressive strength (fc) and dynamic and static elasticity modulus (Ed and Es, respectively). Negatively, the mixtures 20S-0.73 and 20SG19–0.73, with CBA and water/cement ratio of 0.73, showed CPB with the highest air content at 28 days (11.72 % and 10.90 %, respectively). Positively, the mixes REF-0.73 and 20G19–0.73, with water/cement ratio of 0.73 and the last with CBA, presented the highest fc at 28 days (25.34 MPa and 25.05 MPa, respectively). Furthermore, an R² coefficient of 0.18 was determined between the Es results from empirical equations with fc or Ed. This paper showed that more water might be necessary to better concrete mechanical behavior. Also, it was possible to facilitate the determination of Es for CPB with fc and Ed. However, empirical equations for Es with more data, such as water absorption, air content, and unit mass, are required for a better correlation between concrete’s mechanical and physical properties.

Synergetic Role of Nano-/Microscale Structures of the Trifolium Leaf Surface for Self-Cleaning Properties.

Wetting has an essential pertinence to surface applications. The exemplary water-repelling and self-cleaning surfaces in nature have stimulated considerable scientific exploration, given their practical leverage in cleaning window glasses, painted surfaces, fabrics, and solar cells. Here, we explored the three-tier hierarchical surface structure of the Trifolium leaf with distinguished self-cleaning characteristics. The leaf remains fresh, withstands adverse weather, thrives throughout the year, and self-cleans itself against mud or dust. Self-cleaning features are attributed to a three-tier hierarchical synergetic design. The leaf surface is explicated by an optical microscope, a scanning electron microscope, a three-dimensional profilometer, and a water contact angle measuring device. Hierarchical base roughness (i.e., nano-/microscale) comprises a fascinating arrangement, which imparts a superhydrophobic feature to the surface. As a result, the contaminants present on the leaf surface are washed with rolling water droplets. We noticed that self-cleaning is a function of impacting or rolling droplets, and the rolling mechanism is identified as efficient. The self-cleaning phenomenon is studied for contaminations of variable sizes, shapes, and compositions. The contaminations are supplied in both dry and aqueous mixtures. Furthermore, we examined the self-cleaning effect of the Trifolium leaf surface by atmospheric water harvesting. The captured water drops fuse, roll, descend, and wash away the contaminating particles. The diversity of contaminants investigated makes this study applicable to different environmental conditions. And, along with other parallel technologies, this investigation could be useful for crafting sustainable self-cleaning surfaces for regions with acute water scarcity.

ДОСЛІДЖЕННЯ ВПЛИВУ ПОЛІМЕРНИХ ДОБАВОК НА ВЛАСТИВОСТІ ПОРИЗОВАНИХ СУХИХ БУДІВЕЛЬНИХ СУМІШЕЙ

The theoretical prerequisites for obtaining porous mortars modified with polymer additives based on dry construction mixturesand experimental studies on determining the influence of these additives on the parameters of mixture preparation and on the rheological and physico-mechanical properties of porous mortar are presented.The article presents the results of theoretical-experimental studies of the complex influence of polymer additiveson the properties of dry construction mixtures made with an activated mineral component -Portland cement and mineral fillers and microfillers based on local raw materials. The main results of experimental studies of porous compositions of dry mixtures for floors with the addition of polymer additives are given.It was established that the modification of dry building mixtures based on Portland cement and activated mineral fillers withpolymer additives allows to increase by 25-40% the physical and mechanical properties of hardened solutions for floors and to obtain compositions with a compressive strength of up to 16.3 MPa, as well as to significantly improve the rheology of the mortar mixtures and reduce shrinkage phenomena when introducing corrosive additives without increasing the water consumption of the mixture and overusing the binder