Obtaining a robust fiber/matrix interface is crucial for enhancing the mechanical performance of fiber-reinforced composites. This study addresses the issue by presenting a novel physical–chemical modification method to improve the interfacial property of an ultra-high molecular weight polyethylene (UHMWPE) fiber and epoxy resin. The UHMWPE fiber was successfully grafted with polypyrrole (PPy) for the first time after a plasma treatment in an atmosphere of mixed oxygen and nitrogen. The results demonstrated that the maximum value of the interfacial shear strength (IFSS) of the UHMWPE fiber/epoxy reached 15.75 MPa, which was significantly enhanced by 357% compared to the pristine UHMWPE fiber. Meanwhile, the tensile strength of the UHMWPE fiber was only slightly reduced by 7.3%, which was furtherly verified by the Weibull distribution analysis. The surface morphology and structure of the PPy in-situ grown UHMWPE fibers were studied using SEM, FTIR, and contact angle measurement. The results showed that the enhancement of the interfacial performance was attributed to the increased fiber surface roughness and in-situ grown groups, which improved the surface wettability between the UHMWPE fibers and epoxy resins. An ultra-high molecular weight polyethylene (UHMWPE) fiber is characterized by high strength, low density, and outstanding toughness ,2,3. Now+ to improve the wettability and adhesion between the fiber and the resin, showing that the interfacial shear strength increased by 43.3%. Meanwhile, Han et al. [The main methods have been presented by introducing polar functional groups or increasing the fiber surface roughness to improve the interfacial bonding, including the chemical, physical, and physical–chemical process methods ,10,11. Tn et al.  utilizedIn comparison, the physical method has a milder effect on the interface modification, environmental pollution, damage to the fiber, and impact on the properties of the material itself . The comIn general, relying solely on the physical or chemical method usually leads to a decrease in the fiber strength, considerable environmental pollution, or a quick reduction in the modification effectiveness. Recently, combining these two methods became a viable and practical approach for the surface treatment. For example, Cech et al.  initiallTo improve the interface performance between the UHMWPE fiber and the epoxy matrix, a physical–chemical synergistic modification method was presented in this study. The UHMWPE fiber was successfully grafted with polypyrrole (PPy) for the first time after the plasma treatment in an atmosphere of mixed oxygen and nitrogen. The synergy effects of the plasma treatment and in-situ grown PPy on the UHMWPE fiber/epoxy interface were systematically studied using contact angle measurements, infrared spectroscopy (FTIR), a scanning electron microscope (SEM), and mechanical property testing. Through these means, it was promising to significantly enhance the IFSS of the UHMWPE fiber/epoxy without dramatically sacrificing the tensile strength of the UHMWPE fiber. The research results are expected to provide a high-efficiency, economical, and environmentally friendly treatment method for the surface modification of the UHMWPE fiber, and then offer ideas for improving the mechanical properties of the UHMWPE fiber-reinforced composites.The UHMWPE fibers used were provided by China Yixing Xinli Weaving Co., Ltd.  The PPy was prepared by means of a concentration of 40 m mol/L of pyridide  and ammonium persulfate ((NH4)2S2O8, analytical grade, Zhenjiang Jiuyi Chemical Reagent Co., LTD., Zhenjiang, China).The fibers were processed using different treatment methods with the IN2 infusion-type low-viscosity epoxy  resin as the matrix and AT 30 as the curing agent with a mixing mass ratio of 10:3.2:O2 = 5:5, N2:O2 = 8:2, and pure N2.A sub-atmospheric pressure glow discharge processor  was applied to the UHMWPE fibers with a cavity size of 720 (W) mm × 1360 (H) mm × 765 (D) mm. The power was set to 350 w. The UHMWPE fibers were plasma-treated under three different atmospheres, including NThe fibers before and after the plasma treatment were grafted with PPy. The specific process was as follows. First, the samples were placed in the pyrrole aqueous solution and stirred using a magnetic stirrer covered with ice for 10 min. Secondly, the ammonium persulfate was dropped slowly into the above solution and then stir for an additional 30 min. Finally, the samples were taken out and dried in an oven. The plasma–PPy synergistic treatment process is shown in dτ (IFSS) was calculated using Equation (1).maxF is the maximum load (N) when the resin is debonded, d is the fiber diameter (m), and el is the embedding length (m).The microsphere debonding method was used for analyzing the bonding performance of the fiber and the matrix interface. Double-sided tape was used to fix the UHMWPE fiber monofilament on the fixture frame. A fine needle was utilized to dip a small amount of the configured resin-curing agent system (mass ratio 100:30) on the fiber surface. To obtain a microsphere debonding test sample, the resin droplets were solidified according to the same curing process parameters for 6 h under 60 °C. Ten microspheres were selected with the same size and shape as in one group of testing. The YG163 drawing tester  was used to test the bonding performance of the fiber/matrix interface, performing at a 0.2 mm/min loading speed. The UHMWPE fiber monofilament tensile test was performed using the FAVIMAT+ fiber tester  according to the standard GB/T 31290-2014 Carbon fiber Determination of the tensile properties of single-filament specimens with a tensile rate of 2.0 mm/min. Each reported tensile test value was the average of more than ten successful measurements.−1.The Quanta 250FEG scanning electron microscope (SEM) was used to observe the microscopic morphology of the samples before and after the surface treatment. The voltages were 5 KV and 20 KV. The sample surface was treated using plasma sputtering equipment to spray gold to improve its conductivity. The functional groups on the surface of the fibers were analyzed using Fourier transform infrared spectroscopy (FTIR). In the test, the spectrometer’s resolution was set to 4000, and the wavenumber range was 400–4000 cmh is the height of the drop on the surface of the fiber, w is the width of the drop on the surface of the fiber, and θ is the contact angle.The surface tension of the liquid epoxy resin fibers was measured using the static drop method, and the wettability of the fibers before and after the modification was analyzed. The contact angle was calculated according to Equation (2).The changes in the two microspheres before and after the microsphere debonding test are shown in The debonding test results of the microspheres under the different treatment processes are shown in Furthermore, by comparing the interfacial shear strength of the fiber before and after the PPy grafting under the same plasma treatment atmosphere, the interfacial shear strength of the fiber was significantly increased by between 109–353%. Among them, the PF(N5O5)-PPy had the most significant increase, reaching 353%. In general, both the single experimental method and the method of synergistic treatment can improve the interfacial adhesion performance. It should be noted that the synergistic approach resulted in a noteworthy improvement in the IFSS. The process of the surface treatment using PPy grafting and plasma treatment with the mixture of oxygen and nitrogen achieved the highest increase in the IFSS, which showed a 357% higher enhancement than that of the pristine fibers.The PF(N5O5)-PPy only reduced the tensile strength of the original UF monofilament by 7%. After the plasma was treated, cracks, pits, and grooves appeared on the surface of the UHMWPE fibers. Although these defects reduced the tensile strength of the monofilament, they increased the interface performance between the fiber and matrix . After tP(σ) illustrates the fracture probability of N defects under stress σ; F(σ) represents the tensile stress, which is the cumulative probability distribution function corresponding to σ; m is the shape parameter of the fiber, also called the Weibull parameter; σ0 indicates the scale parameter under the corresponding test span; and σ shows the strength test value of the fiber. The failure probability F corresponds to a certain stress level and can be expressed using Equation (5).N is the number of samples of the tested single fiber and i is the serial number of the strength data obtained from the test sorted from small to large.The interior and surface of the fiber monofilament introduced certain micro-defects during its production and surface treatment. The distribution of these defects affected the microstructure and tensile strength of the fiber monofilament. On the contrary, the fiber statistical law of the monofilament tensile strength also reflected the law of the influence of the different manufacturing and surface treatment processes on its microstructure. Since the UHMWPE fiber is a fragile material and follows the weakest chain theory, its tensile strength conforms to the two-parameter Weibull distribution function ,26,27. Tm and scale parameter σ0 of the Weibull distribution function, two logarithms were taken on both sides of Equation (3) to obtain Equation (6).In order to obtain the shape parameter lnσ and lnln(1/(1 − F)) have a linear relationship. Here, a scatter plot of lnσ and lnln(1/(1 − F)), a one-variable linear regression equation and a Weibull distribution double logarithmic graph, were drawn and analyzed. Among them, the shape parameters of the Weibull equation were obtained by calculating the slope of the straight line equation, and the scale parameters of the Weibull equation were obtained using the intercept. The relevant result is shown in It can be seen from Equation (6) that 0 was the size of the tensile strength. With the larger values of σ0, the values of the strength of the fiber increased. A more intuitive view of the data can be obtained from The shape parameter m is a characterization of the dispersion of the strength of the fiber monofilament. The larger the m value, the smaller the dispersion of the strength. The scale parameter σIn the traditional sense, the strength distribution of the UHMWPE fibers can be described by the standard Weibull distribution function and as a normal Gaussian distribution as well . The GauAs shown in −1 and 1510 cm−1. The strong absorption peak at 1037 cm−1 was the stretching vibration of the -CO bond and the wide frequency band at 3040–3400 cm−1. The absorption peak of N-H from 3351 cm−1 decreased to a lower wavenumber 3217 cm−1 (PF(N5O5)-PPy), which indicated that hydrogen bonds formed between the PPy and the UHMWPE interface. Furthermore, the stretching vibration of CH2 was near the absorption peaks of 2914 cm−1 and 2845 cm−1, the absorption peaks were in the range of 1200 cm−1~1300 cm−1 belonged to the -CN stretching vibration, and the absorption peaks of 1536 cm−1 and 1406 cm−1 belonged to the -C=C and -C-C stretching vibrations, which was the characteristic absorption peak of the pure PPy. In In this work, a novel physical–chemical modification method was presented to improve the interfacial property of the UHMWPE fiber and epoxy resin. The UHMWPE fiber was successfully grafted with PPy for the first time after the plasma was treated in an atmosphere of mixed oxygen and nitrogen. It was found that the combined use of the plasma treatment and PPy in-situ grown on the fiber surface was an effective way to significantly improve the adhesion between the UHMWPE fibers and the epoxy resin. The results were expected to propose a surface modification technique for the UHMWPE fiber that would be effective, affordable, and environmentally friendly, hence providing opportunities for improving the mechanical characteristics of composites reinforced with UHMWPE fibers. The following conclusions can be obtained from this work.After the plasma treatment, the UHMWPE fibers were etched with increased surface roughness. Following the PPy in-situ grafting, the surface of the fibers became smooth.2 and N2, resulting in an IFSS of 15.75 MPa and tensile strength of 6.633 GPa.Through a combination of plasma treatment and in-situ grown PPy, the UHMWPE fiber exhibited an optimal modification effect with a balanced atmosphere mixture of OIn comparison to the pristine fibers, the UHMWPE fiber under the combination modification of the plasma treatment and in-situ grown PPy  showed a good balance of interfacial performance and tensile strength. The IFSS was significantly enhanced by 357%, while the tensile strength was only slightly reduced by 7.3%.The enhancement of the interfacial performance was attributed to the increased fiber surface roughness and in-situ grown groups, which improved the surface wettability between the UHMWPE fibers and the epoxy resins.


The early identification of micro-defects in ferromagnetic elements such as steel wire ropes significantly impacts structures’ in-service reliability and safety. This work investigated the possibility of detecting mechanically introduced discontinuities using different magnetic sensors without magnetization of the tested object with a strong external field. This is called the passive magnetic testing method, and it is becoming increasingly popular. This research used differential sensors  and absolute sensors (enabling the measurement of the magnetic field vector module or its components at the microtesla level). Each measurement result obtained from the sensors allowed for detecting discontinuities in the line. The problem to be solved is the quantitative identification of changes in the metallic cross-section of a rope. The first steel wire rope in the world was made by Wilhelm Albert in the 1800s. Steel wire ropes are used in every industry . The most critical defects are wire breakage, strand breakage, rust, wear and fatigue . Many reIncreasing interest has been shown in the development of new methods for diagnosing steel wire ropes. In , the autThus far, none of the existing studies have compared passive magnetic sensors in the context of wire rope diagnostics. This paper aimed to analyze the diagnostic capabilities of sensors using the following phenomena: magnetoimpedance (MI), tunneling magnetoresistance (TMR) and optically pumped magnetometers (OPMs). In this work, particular emphasis was placed on the influence of the distance between the sensor and the tested object, and the direction of the test. The measurement results obtained from various sensors were compared qualitatively and quantitatively. This article aimed to indicate the most appropriate sensor that best shows the modeled failure description as a beginning for further diagnostic calculation algorithms. The traditional magnetic method of wire rope testing is based on formatting the magnetic field from an external source and analyzing the magnetic flux leakage caused by discontinuities ,20,21,22The correlations described in this article were found for many structures of the tested wire rope. This work focused on a test for a representative example of the tested object described here. The tested object was a steel rope with a diameter of 6 mm and a 6 × 19 S + IWRC (7 × 7) construction. This structure is often used in industry due to its flexibility, especially in passenger lifts. The metallic cross-section of the tested object and the strength characteristics are shown in The rope has a 6 × 19 S + IWRC (7 × 7) construction, which means that the rope consists of 6 strands of 19 wires each. The strands have a Seale construction. Thomas Seale patented this design in 1855 in the USA. The Seale strand is characterized by a layer of wires with smaller diameters laid directly on the core, with the next layer consisting of the same number of wires with the same but much more prominent (close to the core) diameters . It causThe subject of ongoing research is the analysis of the possibility of using the passive magnetic technique in diagnosing ferromagnetic objects . Ref. 2 proved tThe SMFL technology creator is AA Dubov, who described this phenomenon as metal magnetic memory (MMM) ,33. He wThe basis of this article is the variety of passive magnetic sensors. This diversity results from other physical phenomena used for the described sensors. This work compared all magnetic signatures from magnetometers available in the laboratory, designated as S1, S2, S3 and S4. The characteristics of these sensors are shown in The S1 and S2 sensors can detect magnetic field variation at the nanotesla level. The sensors consist of a 1-axial magnetic head (MI element) and an electric circuit to operate the MI element. By restricting the cut-off frequency on the low-frequency side to 0.1 Hz, the sensors cancel static magnetic fields such as geomagnetism and only respond to moving ferrous objects with high sensitivity. The S3 sensor is a micro-fabricated atomic magnetometer (MFAM). A miniaturized scalar atomic magnetometer (sensing module) was built to measure changes in the Earth’s magnetic field associated with natural and artificial phenomena. The MFAM sensing module includes two laser-pumped cesium sensors connected to the sensor driver electronics. The S4 sensor is a low-power, 3-axis USB digital vector triaxial magnetometer based on the magnetoresistance tunneling effect (TMR) and quantum magnetic tunnel junctions (MTJs). Sensors S1, S2 and S3, due to their design and measurement methods, do not require calibration, and even their calibration is impossible. In contrast, the S4 sensor requires calibration. Quantitative results of measurements carried out with this sensor depend on its calibration, which can be carried out for any magnetic condition. The calibration process causes the sensor to adopt local values at the calibration site of absolute 0.The essential device involved in the S4 sensor calibration process was the Zero Gauss Chamber 12″ ZG-212, made of a mu-metal alloy , from the Magnetic Shield Corporation (USA). Thanks to the three-layer construction of the chamber, the external magnetic field and the Earth’s geomagnetic field (0.25–0.65 Gs) are suppressed to the level of mGs.The S4 sensor was calibrated in the ZG-212 chamber, treating the value of the magnetic field in it as zero.To verify the indications of the S4 sensor, a Helmholtz coil with laboratory amplifiers was used to generate the appropriate current intensity values. The relationship between the coil’s current and its magnetic field is shown in The S4 sensor was placed in the center of the coil, and measurements were carried out on the changing magnetic field generated by the windings of individual coils. The influence of ambient conditions  was considered. The measurement results of the field values are shown in Each of the sensors, i.e., S1, S2, S3 and S4, was used simultaneously for the magnetic field measurement . Sensor In series 1 of the measurement, the steel wire rope was installed in its delivered state on the stand, according to Series 2 consisted of measurements of the rope in which the test object was changed by introducing, in the middle of the rope, a discontinuity to a depth of approximately 2 mm . The locThe difference between series 3 and series 2 is the change in the lift-off value. The sensors were brought closer to the rope to a distance of 10 mm. At the same time, the S3_1 and S3_2 sensors were replaced, and the distance between them was set to 50 mm . The results of the conducted measurements are shown in Although we measured the same range of the rope under the same conditions, the results were different, which is understandable due to the measurement techniques of each sensor.S1 sensor : CompareS2 sensor : We can S3 sensor : In the S4 sensor : The S4 This research aimed to determine the possibility of using magnetic gauges to detect discontinuities in steel ropes. Three series of measurements were carried out, including measurements on ropes with and without discontinuities, using various configurations of the arrangement of the measuring sensors used concerning the test object. It can be concluded that the results obtained from each tested sensor can be used as diagnostic signals in steel rope defectoscopy. The different magnetic field measurement methods used in these sensors and differences in their design mean that the received diagnostic signals—their distribution along the measuring section of the rope—differ significantly in terms of quality and quantity. The critical issue concerning the diagnostics of wire ropes is the ability to identify signal changes that differ for individual sensors due to discontinuities. These changes result mainly from the measurement method used in a given sensor. Despite these differences, the measurement results of each sensor allow an approximate determination of the location of a single discontinuity.In the case of sensors S1 and S2, the location of the discontinuity was clearly distinguished in the signal waveform, which showed a value close to 0 outside this location. The signal-to-noise ratio for sensors S1 and S2 was high and very satisfactory regarding their use in wire rope flaw detection.The S3 and S4 sensors, in contrast to the S1 and S2 sensors, measure the value of the magnetic induction vector read at a specific point on Earth. A discontinuity introduced on the rope’s surface caused a local magnetic anomaly in the induction distribution. This was particularly visible in the image of the induction components obtained from measurements with the S4 sensor.The sum of the diagnostic information obtained from the tests allows us to conclude that the mutual complementation of sensors using different measurement methods allows for the development of diagnostic tools that can be used in the passive diagnostics of steel ropes. Separate issues and subjects of further research are issues related to the configuration of the sensor or sensors relative to the rope (lift-off), determining the size of the discontinuity based on the diagnostic signal, the impact of external factors and the resolution in identifying closely located defects.


Environmental microorganisms are always present in poultry farming and may be associated with a high concentration of organic dust, microorganisms in feces, litter, dust and air, as well as the release of volatile odorous compounds, feathers, dandruff , mites, bacteria, fungi and fungal spores and endotoxins, depending on the type of bird and stages of the production cycle. Moreover, highly productive poultry raised on private farms always have a lower level of immunity compared to backyard poultry flocks. This is due to high productivity, forage stresses during rearing, cohesive plantings and extensive contact between individuals; all these are the result of a decrease in productivity and, possibly, the development of infectious diseases. However, the use of antibacterial drugs for the prevention and treatment of infectious diseases is associated with a number of undesirable risks, the main of which are the contamination of poultry products and the development of resistance of microorganisms to antibiotics. Thus, we assume that plant-based extracts and phytobiotics used as feed additives can be used as alternatives to antibiotics and can definitely affect the productivity, health and product quality of broiler chickens. The complex phytobiotic feed additives (CPFA) contain the following: tannins, eugenol, cinnamon aldehyde, zinc–methionine, calcium butyrate, silicon dioxide and dextrose.p < 0.05) compared to the minimum level of phytobiotics (200 g/t). From 15–21 days, the live weight was significant between the supplemented and control groups and represented 396.21, 384.81 and 384.16 vs. 316.91 g for the CPFA 4, CPFA 5, CPFA 1 and control group, respectively. Furthermore, the same trend was recorded in the average daily gain during the periods between 15–21 and 22–28 days of the experiment. Feeding CPFA had a positive effect on the carcass indicators, except for the feeding of CPFA 3 in the amount of 600 g/t in the starter phase and 300 g/t in the grower and finish phases, which recorded the lowest weight in relation to the CPFA 1 and 2 groups and represented 1309.58 vs. 1460.06 and 1456.52 g, respectively, and the difference was significant. The inclusion of CPFA in poultry diets contributed to an increase in lung mass in the experimental groups relative to the control group, except for the CPFA 5 group which represented the lowest weight of lung mass (6.51 g) and the differences were significant between the CPFA 2 and CPFA 3 and the control groups. The highest concentration of leukocytes was observed during the experiment period in the group of poultry receiving phytobiotics (CPFA 3), which significantly exceeded the control group by 2.37 × 109/L. A significant decrease in the level of cholesterol was recorded in the CPFA groups when compared to the control group and represented 2.83 vs. 3.55 mmol/L, respectively. Consequently, the introduction of vegetable feed additives from complex phytobiotic feed additives (CPFA) in the diets of Ross 308 chicks had a positive effect on the growth production, the carcass yield, the mass of the pectoral muscles and the mass of the lungs. Moreover, it did not cause a harmful effect on the biochemical parameters of the blood.The purpose of this study was to determine the level of application and effectiveness of the use of vegetable feed additives from complex phytobiotic feed additives (CPFA) in the diets of broiler chickens, as well as their effects on growth indicators, carcass characters and blood profile. A total of 258 Ross 308 chicks were divided into six dietary regimens, including: a basal diet without additives as a first control group (CON); the second group received a basal diet supplemented with 200 g/t in the starter phase and 100 g/t in the grower and finisher phase; the third group—400 g/t and 200 g/t; the fourth group—600 g/t and 300 g/t; the fifth group—800 g/t and 400 g/t; and the sixth group—1000 g/t and 500 g/t of a complex phytobiotic supplement based on tannins, respectively. The CPFA contains the following: tannins 36.8–55.2%, eugenol 0.4–0.6%, cinnamon aldehyde 0.8–1.2%, zinc–methionine 1.6–2.4%, calcium butyrate 8–12%, silicon dioxide 1.2–1.8% and dextrose up to 100%. The maximum introduction of phytobiotics (1000 g/t) at 7 days of age leads to a decrease in the live weight of broilers which reduced by 8.27% ( In recent decades, there has been a significant growth in the human population on the planet, and according to some sources, the earth’s population will amount to 10 billion people by 2050, which will directly lead to an increased demand for food, especially inexpensive meat products produced from the meat of farm animals, including poultry . ConsequPoultry farming is characterized as the most intensively developing branch of agriculture in the world. Thus, according to the assessment of the Economic Research Service of the US Department of Agriculture, over the past 20 years, poultry has become the most consumed livestock product in the world, especially in developing countries. An estimated increase of 121% in poultry meat production is expected which is much more significant to 66% of beef and 43% of pork ,6.Based on the latest estimates, the world production of broiler chicken meat, which in 1961 was about 7.56 million tons, will increase in 2025 than 139.19 million tons, which is 17.0 kg of meat per person. The most significant increase in poultry meat production is observed in Brazil, Russia, Indonesia, Japan and India [To fully meet the increased demand for animal food products, countries have increased their domestic production. At the same time, Brazil, the United States, the European Union and Thailand are major producers and exporters of poultry meat. Simultaneously, it is noted that Brazil will be the world’s leading exporter until 2031; at the same time, there is a decline in production in the United States. The high demand for poultry products is also due to the recognition of poultry products as healthier alternatives to human nutrition, characterized by a higher protein content and a lower lipid content. At the same time, the meat of broiler chickens contains more protein of a high-grade amino acid composition compared to the meat of other types of farm animals ,5,6,7.An extensive system of poultry farming began to use antibiotics as growth stimulants, as in the basis of veterinary and sanitary measures ,9,10. ThIn the countries of the European Union, 25 thousand deaths per year from antibiotic resistance have been recorded. The emerging phenomenon of antibiotic resistance has become a serious medical and environmental problem of mankind, since the residual amounts of antibiotics accumulate in animal products and also enter the external environment . As a reThis animal study has been reviewed and approved by the Ethics Committee of the Russian State Agrarian University—Moscow Timiryazev Agricultural Academy (protocol 2022-8 date 6 May 2022).The present research was conducted from 29 July 2022 to 2 September 2022 on the basis of the Center of the Safety and Effectiveness of Feed and Additives of the Research Institute for Advanced Research and Innovation in the Agro-industrial Complex of the Volgograd State Agrarian University . By the method of balanced groups of analogues, taking into account their origin, general development and live weight, six groups of Ross 308 cross broiler chickens were formed. The chickens were purchased at the poultry farm of the KHK JSC Krasnodonskoe of the Ilovlinsky district of the Volgograd region. A total of 258 chicks aged 1 day were randomly divided into six groups. The number in each group was 43 heads .The entire experimental bird was kept in one poultry house. The separation into sections of equal area of 1300 × 1500 cm was carried out using partitions that do not allow the mixing of chickens. The system of keeping chickens is outdoor with the use of deep litter (sawdust). The birds had free access to food and water. The microclimate indicators corresponded to the requirements of the content of the cross. Bunker feeders (one feeder per group) were used to ensure the feeding of the bird; feeding was carried out manually daily.Nipple drinkers with drop catchers (seven drinkers per group) were used to ensure the watering of the bird. In the course of the experiment, complete compound feeds with the same nutritional value and chemical composition were used in feeding broiler chickens. Thus, the conditions of keeping and feeding, planting density, watering and the feeding front of chickens in all groups were identical and met the requirements of the Ross 308 cross. The scientific experiment included the entire period of broiler chickens growing, which lasted for 35 days.Chickens of all groups were fed the same complete compound feeds , which were balanced in nutrients, metabolic energy and amino acid ratio and corresponded to the recommended nutrition characteristics of broiler chickens of the Ross 308 cross of Aviagen (2022)  Table 2. FeedingCastanea sativa Mill, calcium butyrate, zinc–methionine, cinnamon aldehyde and eugenol. The feed additive contains the following (provided by the manufacturer): tannins—36.8–55.2%, eugenol 0.4–0.6%, cinnamon aldehyde 0.8–1.2%, zinc–methionine 1.6–2.4%, calcium butyrate 8–12%, silicon dioxide 1.2–1.8% and dextrose up to 100%.The feed additive under study is a powder from pale brown to brown in color; the main active constituents of the used feed additive are the tannins of the The studied additive was introduced into the composition of compound feeds as part of a premix by stepwise mixing on the basis of the feed mill of Megamix LLC. Tannins were not introduced into the diet during the second finishing period. Formulas for the complete feed for poultry were developed using the computer program Feed Optima (v. 2020.8.17251), taking into account the chemical composition of the components, which was determined at the scientific testing center Cherkizovo .Before the preparation of rations, each raw material was subjected to nutritional value analysis. The moisture content (%) in all samples was determined in accordance with the standard methods of the Association of Official Analytical Chemists. Humidity (2000)  was deteThe content of the ether extract was determined by extraction with petroleum ether (method 920.39). The crude protein content (N × 6.25) (method 976.05) was determined by the Kjeldahl method using an automatic analyzer Kjeldahl, K1100F .PEF) were taken into account (Formula (1)) [n = 43) in each group was carried out to determine the dynamics of live weight and calculate the average daily and absolute growth of the chickens, starting from the daily age of the birds to weekly .To assess the productivity of broiler chickens, the dynamics of live weight (LW), average daily gain, livestock safety, feed costs per 1 kg of live weight gain, and the production efficiency factor (ula (1)) . The indWeighing was carried out using the electronic laboratory scales Mercury 122ACF-3000.05 . With a discreteness of 0.05 g, the live weight of the chickens was recorded in the forms of individual weighing of broiler chickens.The live weight (g) was determined by the control individual weighing of broiler chickens at the age of 7, 14, 21, 28 and 32 days, and before slaughter.AWG, g) is the increase in live weight over the period of the experiment; it was determined using Equation (2):The absolute live weight gain  and W1 is the live weight of the broilers at the beginning of the growing period .3.ADG, g)—calculated by the weighing results; determined by Formula (3):Average daily gain  were calculated based on the data of the feed consumption log and gross body weight gain in each group. Feed costs per 1 kg of live weight gain (kg)—by dividing the amount of feed consumed over the entire period of the experiment by the live weight gain of the broiler chickens during the growing period.5.The safety of the livestock was calculated as the ratio of livestock at the end of cultivation to livestock at planting, expressed as a percentage.During the feeding trial, the number of deaths was counted to calculate the survival rate as the percentage of the surviving to the initial number of broilers.At the age of 35 days, in accordance with the methodology of the All-Russian Scientific Research and Technological Institute of Poultry Farming , a contrAll broiler chickens from each group with a body weight close to the average value for the group were selected for studying carcass quality. The selected chickens were not given food for 10 h before slaughter, while provided with constant access to water. The broilers were killed in accordance with the recommendations by the FOSR for the euthanasia of experimental animals.In the process of slaughtering, the following parameters of meat productivity were taken into account: the mass of the gutted carcass (g), the mass of the pectoral and femoral muscles, shin muscles and the mass of the internal organs . Anatomical cutting was carried out on the basis of the testing laboratory analysis of feed and livestock products at Volgograd State Agrarian University.To assess the biochemical parameters and the direction of metabolism in the poultry body, we conducted blood sampling in order to study the biochemical  and morphological  parameters.Blood was taken from thirty animals from each group with average live weight at the age of 35 days of life. The blood samples were taken at slaughter by an internal method, cutting the junction of the jugular and bridge veins in the oral cavity.The samples for the biochemical blood testing were collected in vacuum tubes with a coagulation coagulant . After the test tubes were centrifuged at 3000 rpm for 10 min, the separated serum was moved to sterile Eppendorf-type test tubes. The serum was stored at −20 °C for further analysis. Biochemical blood parameters were determined in a laboratory  using an automatic biochemical and enzyme immunoassay analyzer ChemWell 2910 Combi .Whole blood for research was collected in tubes with K2 EDTA . The morphological parameters and hemoglobin were analyzed using the MEK 6450 analyzer , using AVANTOR control materials. Coloring: by May-Grunwald ; microscopy using Meiji Techno Nikon .Before carrying out the statistical analysis, all data were tested for normality and homogeneity by Shapiro–Wilk’s and Levene’s tests, respectively. Before processing the percentile data, an arcsine transformation was used . The datThe results of the dynamics of the live weight of the Ross 308 cross broiler chickens are given in When starting the study, the initial live body weights of the chickens were nearly identical; the difference in the average values did not exceed 1%. At 7 days of age, the chickens in the CPFA 4 group recorded the highest live body weights, while the chickens of the CPFA 5 group represented the lowest body weights and represented 173.05 vs. 155.40 g for the CPFA 4 and CPFA 5 groups, respectively, and the difference was significant. On the other hand, at the age of 14 days, the differences between the experimental groups were not significant and the highest value was recorded in CPFA 4 (433.79 g), while the lowest was recorded in the control group (417.05 g). Throughout the subsequent intervals , the differences between the groups were significant. At 21- and 28-days-old, there was a significant difference between CPFA 4 and the control group and the values represented 840.00 vs. 733.95 g and 1381.86 vs. 1254.42 g, respectively.The live weight of the chickens in the 2nd, 4th and 5th experimental groups was higher compared to the control group by 3.61%, 4.21 and 5.85%, respectively; however, the chickens fed tannins in the maximum experimental amount had the lowest live weight at the age of 7 days—4.95% less than the live weight of the control chickens group. At the age of 14 days, the chickens of all experimental groups outperformed the control group in live weight by 6.96%, 1.34, 2.46, 6.41 and 3.79%, respectively. Moreover, at the age of 21 days, the live weight of the chickens receiving tannins as part of compound feeds exceeded the live weight of the chickens without their inclusion by 13.11%, 2.54, 3.61, 14.45 and 11.41%, respectively. The chickens of the CPFA 3 group did not significantly differ in live weight from the control group at the age of 14 days or at the age of 21 days, while the chickens of the CPFA 4 group recorded a significant difference in live weight when compared to the control group and represented 480.00 vs. 733.95 g at the age of 21 days. At 28 days, the live weight of the chickens in the CPFA 2 and CPFA 3 groups were identical to the values of the control group, while the highest values of live weight were set in the CPFA 4 group of chickens receiving phytobiotics in the amount of 800 g/t in mixed feed for the starter phase and 400 g/t in mixed feed for the grower and finisher phase.p < 0.05), which amounted to 2007.91 g, while the live weight of the chickens not receiving the additive was 1875.35 g. The chickens in CPFA 4 were also characterized by a higher live weight and represented 1994.65 g, and the difference with the CPFA 2 group, which recorded the lowest final live weight (1849.07 g), was significant. On the other hand, the live weight of the chickens in the CPFA 1 and 3 groups was slightly lower than the control values. The productivity indicators of the broiler chickens are shown in At the end of rearing, the broiler chickens in the CPFA 5 group were distinguished by the highest values of live weight—7.07% higher than in the control group . During the period from 15–21 days of rearing under the study, the absolute live weight gain recorded a significant difference between the supplemented and control groups and represented 396.21, 384.81 and 384.16 vs. 316.91 g for CPFA4, CPFA5, CPFA1 and the control group, respectively. Furthermore, the same trend was recorded in the average daily gain during the periods between 15–21 and 22–28 days from the start of the experiment. At the age of 35 days, a controlled slaughter and anatomical cutting of broiler chicken carcasses was carried out. The results explaining this are presented in Generally, the absolute live weight gain from the start of the experiment to the end revealed significant differences between the supplemented groups only, while when compared with the control group the differences were As a result of feeding with a complex phytobiotic feed additive, the weight of the un-eviscerated weight gutted bird carcass had a positive effect on the carcass indicators, except for the feeding of CPFA 3 in the amount of 600 g/t in the starter phase and 300 g/t in the grower and finisher phase, which recorded the lowest weight in relation to the CPFA 1 and 2 groups and represented 1309.58 vs. 1460.06 and 1456.52 g, respectively, and the difference was significant. Regarding the production of pectoral muscles, it should be noted that the mass of the pectoral muscles was characterized by the worst indicators in CPFA 3 chickens, where this indicator was 332.43 vs. 385.96 g against the control group, while the highest weight of pectoral muscles was recorded in the CPFA 1 group which represented 459.19, and the difference between the CPFA 1 and CPFA 3 groups was significant.p < 0.05) in the size of the spleen in chickens receiving a minimum level of phytobiotics in the amounts of 200 and 100 g/t, respectively.The inclusion of CPFA in poultry concentrates contributed to an increase in lung mass in the experimental groups relative to the control group except for the CPFA 5 group, which represented the lowest weight of lung mass (6.51 g) and the differences were significant between the CPFA 2, CPFA 3 and control groups. The use of a phytobiotic dosage in the amount of 200 g/t and 300 g/t (CPFA 2 and CPFA 3) in the grower and finisher phase is 1.48- and 1.54-times the weight of the lungs higher compared to the control. However, in the CPFA 1 group, there was a decrease , which significantly exceeded the control group by 2.37 × 109/L, respectively. With reference to the content of hemoglobin, there were no significant differences between the experimental groups, while the highest level was recorded in the CPFA 4 group and represented 126.67 g/L, while the lowest value was recorded in the CPFA 2 group and represented 121.33 g/L.The concentration of erythrocytes in the blood of the control chickens, CPFA 1, CPFA 4 and CPFA 5 groups was also approximately at the same level; however, in the blood of the chickens of CPFA 2 and 3, the content of erythrocytes was the lowest, yielding slightly to the control by 6.15 and 7.31%. The most significant difference was found in the level of leukocytes. Chickens with the highest live weight at the end of rearing were characterized by a reduced content of leukocytes in the blood (CPFA 4 and CPFA 5), while in the blood of chickens with the lowest weight, the level of leukocytes was higher than the control values by 12.58–25.48% (CPFA 2 and CPFA 3). The highest concentration of leukocytes was observed during the experiment period in the group of poultry receiving phytobiotics , except for the cholesterol level, which recorded a significant decrease in the CPFA 1, 2 and 4 groups when compared to the control group of chickens and represented 3.44, 3.11 and 2.83 vs. 3.55 mmol/L, respectively. On the other hand, the other supplemented groups (CPFA 3 and 5) did not reveal significant differences when compared to the control chickens.The introduction of phytobiotics at different levels did not negatively result in changes in the biochemical parameters of the blood in the different experimental groups. Moreover, all the obtained biochemical indicators were within the reference physiological values. On the same side, none of the biochemical parameters revealed any significant differences between the different experimental groups  proved to be worse than an antibiotic. It is probable that higher dosages of phytobiotics of 100–1000 g/t for up to 7 days tend to manifest themselves more as anti-nutritional substances that prevent the normal colonization of the gastrointestinal tract with normal microflora. The negative effect of higher doses of tannin extracts can be explained by a significant decrease in feed intake, which leads to a decrease in body weight gain, which is consistent with the results of studies [The introduction of phytobiotics at the maximum level 1000 g/t) had a negative effect on the growth of broiler chickens in the fifth group at the age of 7 days in relation to the other experimental groups. It is well known that adult chickens develop resistance to pathogenic bacteria after the native microflora becomes established. This was probably due to the fact that the tannins were fed with nutraceuticals and had a predominantly inhibitory effect on the digestive process, and, consequently, the poultry of this group grew more slowly. In the later growing periods from 8–14 days, it did not affect the growth rate of the poultry in this study 200–500 g/t), which was also observed in several other studies ,46,47,480 g/t, wh studies ,39. The 00 g/t ha studies . SubsequConsidering the cutting of carcasses, the yield of a half-gutted carcass was significantly affected by the level of use of a phytogenic feed additive. So, the worst in this indicator was a bird that received a growth phase of 300 g/t of phytobiotics before slaughter and 600 g/t of feed additive in the starter phase. It is probable that such a lower value is due to the fact that higher dosages were used at earlier periods of rearing and, accordingly, the bird gained weight more slowly. However, when comparing between groups for this indicator, for the bird receiving the minimum levels of phytobiotic (100 g/t and 200 g/t), the difference was significant. Similar results were obtained for the weight of the pectoral muscles, which were higher when the phytobiotic was administered in an amount of 100 g/t compared with a dosage of 300 g/t from 11 to 30 days of rearing. The content of the individual organs, such as the lungs, in animals receiving 200 and 300 g/t of feed phytobiotic additives was higher by 48.2% and 53.9%, respectively, which probably contributed to a more intensive gas exchange, and, consequently, higher feed consumption.The organs of hematopoiesis include the liver and the spleen in which the synthesis and decay of blood cells occur. The spleen in birds is a separate small-sized organ, characterized by a variety of shapes. The spleen not only destroys, but also accumulates, shaped blood elements—erythrocytes, leukocytes and platelets. Based on our results, it was found that the spleen of all birds from the supplemented groups were smaller than the control group; in particular, the bird that received the lowest dosages of phytobiotic feed additives throughout the rearing had a significant decrease in its weight compared to the control. The role of the spleen is very significant because it is responsible for the capture and destruction of endotoxins, insoluble components of cellular detritus in burns, injuries and other tissue damage, its cells recognize antigens foreign to this organism and synthesize specific antibodies.The use of a single substitute or ideal combinations of various alternatives  with the proper management and practice of animal husbandry can play a key role in maximizing productivity and maintaining animal productivity ,52,53,54According to a recent study by Lillehoj et al. (2018), the use of a mixture of several phytochemicals has a synergistic effect to reduce the negative effects of intestinal infections . AccordiThe effect of carvacrol, cinnamon aldehyde and capsicum oleoresin on the regulation of gene expression related to immunology, physiology and metabolism was investigated in Kim et al. (2010) in chickens using high-performance microchip analysis . AccordiBlood cells play an essential role in the body of animals; for example, they are responsible for the transport of nutrients, the exchange of gases, provide protection to the body and have the ability to synthesize immune bodies ,63,64,65The biochemical parameters of a bird depend on many factors, such as the environment, the conditions of keeping and feeding, as well as the level of stress. Many authors demonstrated that probiotics, probiotic and phytobiotic feed additives can have significant influence. Others, on the contrary, claim that these additives do not significantly affect the biochemical parameters of animals ,61,62.The biochemical parameters of the serum show the metabolism of nutrients in the body and emphasize possible changes caused by internal and external factors ,64,65. Ip > 0.05). The data obtained by us are consistent with the data of Basit et al. (2020) [The serum concentrations of cholesterol and triglycerides are considered indicators of lipid metabolism . In term. (2020) , whose s. (2020) , who rep. (2020) . Gilani . (2020) . Zeng et. (2020) .p > 0.05) and glucose concentration was increased (p < 0.05) in Z. officinale, while triglyceride concentration was increased (p < 0.05) in Z. officinale and S. Aromaticum [In our studies, it was found that feeding in the initial period of 800 g/t CPFA (group 4) had a negative effect in the growth of live weight up to 7 days of age, probably due to a decrease in the activity of the microbiota of the digestive tract. However, Tekeli et al. (2006) indicate that the inclusion of phytobiotics did not affect cholesterol concentration (omaticum .Castanea sativa mill extract in combination with calcium butyrate, zinc–methionine and essential oils had a positive effect on the live body weights of broilers, increased the mass of lungs and, moreover, did not cause any harmful effects on the blood profile of Ross 308 broiler chickens, while decreasing the level of cholesterol in some supplemented groups. Moreover, we can conclude that the ideal dose of CPFA for the usage in diets of Ross 308 chickens is 800 g/t in the starter phase and 400–500 g/t in the grower and finisher phase in order to increase the meat production and zootechnical characteristics.Based on our results, the introduction of complex phytobiotic feed additives containing


This study reports the preparation of geopolymers with a mechanical performance similar to that of cement at room temperature by ground fly ash mixed with a small amount of cement. The grinding time of fly ash raw materials was 0,20,40 and 60 min, respectively. The influence of the grinding degree of the fly ash on the properties and the reaction degree of the geopolymer were investigated by XRD, SEM, EDS, and mercury compression tests. The reaction degree of the fly ash geopolymer was quantified by the selective dissolution method. Increasing the grinding degree of fly ash significantly increased the compressive strength of the geopolymer and the density of the microstructure of materials also increased. Furthermore, porosity and the average pore size decreased and the proportion of small holes in the pores gradually increased. The calculation results were in coincidence with the compressive strength test and the micro-performance test of the material, thus indicating that the selective dissolution method can reflect the influence of the grinding degree on the reaction degree of the geopolymer. Furthermore, the reaction degree of the geopolymer increased as the grinding degree of the fly ash increased. However, the growth rate of the reaction degree for the geopolymer slowed down when the fly ash was ground for more than 40 min. ReseaThere are three ways to activate fly ash in the process of preparing fly ash geopolymers: thermal activation, chemical activation and mechanical activation. Some studies have shown that geopolymers with similar mechanical properties as cement can be prepared by appropriately increasing the curing temperature ,14. On tAlthough the chemical composition of the fly ash does not change after grinding, mechanical grinding destroys the dense glassy shell of fly ash particles, releases the active components inside, reduces the average particle size of fly ash particles, increases the contact area between the fly ash and activator, and increases the dissolution rate. In addition, according to the law of conservation of energy, part of the mechanical energy is transformed into kinetic energy between the particles in fly ash, which improves the activity of fly ash –31. SzabThis research adopts the method of mechanical activation to prepare fly ash with different grinding degrees, and fly ash geopolymer with comparable mechanical properties to cement was prepared at room temperature. The effects of grinding degree of fly ash on the fluidity, compressive strength, microstructure, crystal phase product, pore distribution and reaction degree of geopolymer were investigated from macro and micro perspectives. A quantitative calculation formula for the reaction degree of geopolymer after fly ash grinding is proposed. An objective and effective method for evaluating the effect of different grinding degrees of fly ash on the performance and reaction degree of geopolymer is provided under normal temperature conditions.2 mass fraction of 27.3%, and a Na2O mass fraction of 8.54%.In this passage, F-grade low-calcium fly ash produced by Fuxin Thermal Power Plant was utilized as the raw material for manufacturing geopolymers. To improve the early strength of the geopolymers, a small amount of ordinary 42.5 grade Portland cement (15%) was added. Cement was produced from Fuxin Daying Cement Plant. The basic chemical compositions of the fly ash and cement are presented in The XRD patterns of the fly ash and cement are depicted in Mechanical activation process is that the raw materials of fly ash are mechanically activated by LSYM-5L basket grinder produced in Nanjing, China. The raw materials of fly ash are ground by dispersed blades, and the grinding speed was stable at 2000r / min. Based on the previous test, it was found that the short grinding time interval had no obvious effect on the performance of the sample. Fly ash raw materials undergoes three different activation grinding times: 20, 40 and 60 min to prepare for benchmark tests. The particle size of fly ash can be reduced by mechanical activation, and the dense glass phase shell on the surface of the particles can be destroyed. The pozzolanic activity of fly ash increases significantly.2/Na2 and H2O/Na2O is 1.8 and 3.9, respectively. FG0, FG1, FG2 and FG3 represent the preparation of fly ash based geopolymers with original fly ash and fly ash with different grinding time as raw materials after adding 15% cement 4- and [AlO4]4- are dissolved out. In the second stage, the polycondensation reaction of [SiO4]4- and [AlO4]4- occurs, and the system begins to generate a gel-like reaction product. Finally, due to the further recombination and polymerization of the gel-like reaction product, semi-crystalline zeolite is formed which then begins to harden. As the curing time increases, Si and Al elements in the system continue to react in strong alkali environment to produce gel-like reaction products. As the gelatinous reaction product increases, the architecture becomes compact thus leading to an increase for the compressive strength.The reaction process of geopolymers involves a complex chemical reaction process of alkali aluminosilicate polymers. Glukhovsky  was the 4]4- and [AlO4]4- in fly ash and promoted the depolymerization-polycondensation reaction of the geopolymer, which accelerated the reaction process of the whole system. The small fly ash particles formed after grinding maintained the dominant advantage and generated more reaction products during the curing process. This explains why the reaction degree of fly ash particles after grinding in strong alkali environment was greater than that of original fly ash particles. The compressive strength increased as the reaction degree increased and the internal structure of the system became compact, which is also highly consistent with the previous macroscopic and microscopic test results.In this study, the effect of grinding on the fly ash is presented in The average particle size tended to decrease with an increase of the grinding degree. The small particle size distribution increased, while the large particle size distribution tended to decrease. The average particle size of the fly ash decreased from 9.2448 μm to 5.8662 μm with a milling time in the range 0 to 60 min, corresponding to a decrease of approximately 36.5%.The grinding degree of fly ash particles was positively correlated with the compressive strength of the geopolymer. At 28 d, the compressive strength of the geopolymer manufactured from fly ash after grinding for 60 min was approximately 109.7% higher than that of the geopolymer prepared by unground fly ash.The small particles filled the pores between the large particles with an increase in the grinding degree, where the proportion of harmless pores significantly increased. The increase in the reaction products rendered the structure of the geopolymer compact. The average pore size was reduced by 737.6nm and porosity by 38.3% from 0min to 60min at 28d.The dense glass phase shell on the surface of fly ash particles that hindered the reaction of fly ash was destroyed after grinding. Meanwhile, fly ash was broken into a large number of small particles. Increasing the specific surface area increased the contact area between the alkali solution and fly ash, which accelerated the reaction process and enhanced the reaction degree. The reaction degree of the geopolymer prepared by ground fly ash for 60 min was higher by 70.3% than that of the geopolymer prepared by the original fly ash at 3 d and was 28.6% higher at 28 d. However, the trend of increasing the reaction degree of fly ash was nonlinear with the increase of the grinding degree.S1 Fig(XLSX)Click here for additional data file.S2 Fig(XLSX)Click here for additional data file.S3 Fig(XLSX)Click here for additional data file.S4 Fig(XLSX)Click here for additional data file.S5 Fig(XLSX)Click here for additional data file.S6 Fig(XLSX)Click here for additional data file.S7 Fig(XLSX)Click here for additional data file.S8 Fig(XLSX)Click here for additional data file.


The increasing densification and diversification of modern and upcoming wireless networks have become an important motivation for the development of agile spectrum sharing. Radio environment maps (REMs) are a basic tool for spectrum utilisation characterisation and adaptive resource allocation, but they need to be estimated through accurate interpolation methods. This work evaluated the performance of two established algorithms for spatial three-dimensional (3D) data collected in two real-world scenarios: indoors, through a mechanical measuring system, and outdoors, through an unmanned aerial vehicle (UAV) for measurement collection. The investigation was undertaken for the complete dataset on two-dimensional (2D) planes of different altitudes and for a subset of limited samples (representing the regions of interest or RoIs), which were combined together to describe the spatial 3D environment. A minimum error of −9.5 dB was achieved for a sampling ratio of 21%. The methods’ performance and the input data were analysed through the resulting Kriging error standard deviation (STD) and the STD of the distances between the measurement and the estimated points. Based on the results, several challenges for the interpolation performance and the analysis of the spatial RoIs are described. They facilitate the future development of 3D spectrum occupancy characterisation in indoor and UAV-based scenarios. The function of REMs within the HC2WA framework reflects the spectrum information exchange between the end user devices (EUDs) and the spectrum access control (SAC) units for the provision of services (The proliferation of wireless communications in more and more aspects of everyday life has led to increased advancements in bandwidth-intensive applications that require low latency and the agile processing of radio-frequency (RF) signals ,2. Naturnetworks . The HC2services . The speTherefore, the dynamic change of spectrum utilisation in time, frequency, and 3D space should be considered, in order to characterise the resource availability. Respectively, the REMs need high accuracy even though they are to be estimated from a very limited number of samples, so as to achieve computationally light spectrum sharing . This isAn evaluation of interpolation efficiency was performed for RF data gathered in real-world indoor and outdoor scenarios, in 2D space for different altitudes, which provides insight into the exploration of the same methods in the case of spatial 3D data when only a limited number of samples is available. A normalised root-mean-squared error (NRMSE) of as little as −9.5 dB was achieved for a sampling ratio of 21%. The characteristics of the methods’ performance and the processed measurement samples were analysed by the Kriging error STD values and their densities and the STD of the distances between each measurement point and the estimated points.Several challenges for the future development of REM interpolation methods and for the analysis of spatial RoIs are described, on the basis of the signal propagation characteristics’ influence on the interpolation accuracy. These challenges facilitate the further investigation into the spatial 3D spectrum occupancy in indoor and UAV-based experimental setups.The contributions of this work are as follows:The rest of this paper is organised as follows. A review of relevant literature sources is presented in Research into methods for REM construction has expanded significantly to include measurement methodologies, interpolation in the temporal, spatial, or frequency domain, as well as application-specific topics, such as throughput maximisation, spectrum sharing, coverage mapping, and UAV path optimisation ,24,25. MAlternatively, the input sparse measurements tensor can be vectorised to apply a modified compressed sampling method . The proThe specific goal of many of these works is to optimise the collection of measurements via UAVs, which also benefits from REM construction based on limited samples, as the aerial nodes have stringent operation time constraints and cannot fly into areas with large obstructions. Additionally, improving existing interpolation techniques for spectrum mapping in 3D space has also been explored for indoor locations based on measurements obtained via stationary SDR sensors ,30.This is common for the RF transmitter (TX) sources, the spectrum occupancy characterisation of which is described to be stationary and transmitting at a constant power level. At the same time, due to the difficulty and cost of the implementation of experimental setups that include UAV nodes, only data generated via deterministic models ,12,14,15This experimental setup was realised in a large indoor location a that inx-coordinate) and width (y-coordinate), from the starting point to each consecutive one until the finishing location was reached, covering an area of 12 m2  at an The following RCs were utilised for this experiment: Futaba T14SG (controls the Freefly ALTA X), DJI Matrice 600 Pro Radio Controller, DJI Inspire 2 Remote Controller, and DJI Mavic 2 Enterprise Dual Smart Controller. They operate at frequency bands in the ranges of 2.4–2.483 GHz and 5.725–5.825 GHz, which are used for telemetry, command and control, and video reception purposes for the UAVs. For waypoint trajectory planning and the execution of the sensor UAV, the missions were created using the QGroundControl software Version 4.2.0 and uploaded before launch. To determine the frequency band that would be measured, the sensed UAVs were set into a preliminary flight trajectory (while the sensor UAV was offline), and through a manual search using the GNU Radio’s time and frequency analysis tools, a bandwidth that had significant and frequent emissions would be chosen. In this case, that was the 20 MHz bandwidth at a central frequency of 2.427 GHz. Mounted on the sensor UAV, the laptop Lenovo ThinkPad X250 (weight of 1.3 kg) operated the SDR via a universal serial bus (USB) 3.0 connection and was equipped with a Core i3 5010U processor, 4 GB of RAM, and a SSD with a speed of up to 6 Gb/s, under the Ubuntu 20.04 operating system. The Nuand  BladeRF 2.0 micro SD is applicable for UAV-based measurements due to its compact dimensions (11 cm × 7.4 cm × 2.5 cm), weight of about 200 g, and its notable Analog Devices AD9361 transceiver frontend . The SDRB Hz  ones, depending on the distance shown in :(1)P^ were determined empirically from the resulting function γh=1ribed in ).h between every two points, the nugget, sill, and range [The Kriging weights nd range . FinallyThe Kriging method was implemented in the following steps:For the two scenarios, the parameters related to the data and simulations are listed in The simulations for the complete set of measurements followed a similar methodology to the one described in  for the  minimal ,38); (2)lysis in  to be thOnce the values of  data in , i.e., IK folds were computed, which were then averaged for each plane over all histogram bins at each iteration. Finally, the mean of the STD values and their densities over all iterations were obtained, and their relationship is illustrated in The results for both methods had very similar performance, and their NRMSE curves followed the same distributions. It is notable that the accuracy was about 0.5 dB smaller for the measurement data gathered at the lowest level of height and that the IDW method yielded about a 0.2 dB improvement, compared to Kriging. In addition, for the IDW case, there was a slight increase in the error at a height of 0.25 m, while for the two highest levels, there was very little variety, which also held for the results at 0.25, 0.5, and 0.75 m for the Kriging method. The NRMSE had negligible variations for As for the outdoor scenario, the results are presented in on of σK  was perfDistinct from the error STD in the indoor scenario, the same metric here differed significantly with the change of altitude. For each plane, This uniformity for the planes at altitudes of 90, 100, and 110 m led to the similar distributions of their NRMSEs. A drastic growth for ltitudes .In this subsection, on the basis of the preceding experiments performed both in  and abovribed in , the recThe results for the interpolated 3D measurements from a limited set of samples are presented in As described above, the NRMSE was evaluated for a varying number of estimated samples  data in , for a sTo analyse these relationships, the STD In the outdoor scenario, the NRMSE exhibited some distinct characteristics in comparison to the alternative, even though the IDW was more accurate than Kriging. The difference between them was nevertheless much smaller, with it being substantial only for  for σME c, which On the other hand, the NRMSE of the Kriging method rose significantly for As observed from the results of both scenarios, the fluctuations of Both the Kriging and IDW methods converged to an NRMSE below 0 dB, which makes them suitable for limited real-world 3D RF data, and the achieved accuracy was not significantly lower than in the case where the complete set of measurements was available (shown in the previous work ). In comRelevant challenge: To increase the interpolation efficiency for REM construction, precise mechanisms for RoI determination should be developed, such that the characteristics of the environment are considered. The two scenarios for which the interpolation was evaluated were characterised either by fast-changing (difference of below 0.5 dB between every two measurements) received signal power throughout the entire measurement volume (indoor scenario) or by the notably slower rate of change for most of the measurements (outdoor scenario). The RF data for the former scenario were influenced by the experimental setup of a slow-moving receiver in an indoor environment (within a volume of 6 × 2 × 0.75 m), which included severe multipath propagation, thus requiring an even higher resolution of the measurements [urements . On the polation , sensingpolation , autoencpolation ,39, and polation  or of thpolation .As observed from the previous works ,24, whicRelevant challenge: The environment in which the spatial 3D measurements are collected needs to be considered in the planning of the experimental setup and in the design of the interpolation and prediction methods. Measurement planes at low heights require more measurement samples , especially in an indoor environment. Therefore, an algorithm for multipath propagation prediction can be employed to identify the RoIs and optimise the measurement collection at multiple heights, while its results are validated through preliminary measurements on a single plane. The novel generative adversarial networks and convolutional and graph neural networks [networks ,41,42,43networks . Such menetworks ,24.The adequacy of available RF datasets for REM construction should be evaluated depending on the scenario for which the interpolation is to be performed. There are several types of datasets that have been commonly utilised in recent literature—mobile networks in various outdoor areas ,43, UAV-Relevant challenge: In order for more-accurate and -adaptable interpolation methods to be developed, there is a need for: (1) the generation of sufficiently large datasets for each relevant scenario; and (2) the study of the current datasets’ adequacy for training in more challenging scenarios with multiple transmitter and receiver types. Both of these aspects are relevant to the field of spectrum occupancy characterisation through REM and spectrum sensing, but each has its own challenges. The generation of datasets in complex scenarios may often be very difficult and/or expensive, especially if the experimental setup includes multiple UAVs. On the other hand, the usage of publicly available datasets necessitates the further analysis of their features , which is to be considered in the design of REM prediction and interpolation algorithms, and in the interpretability of their results, which is of great interest for resource allocation and network planning.The experimental results presented in This paper presented an evaluation of two of the most-prominent interpolation methods (Kriging and IDW) for RF data collected in two relevant real-world scenarios. The complete sets of measurements in 2D space and for the limited subset in 3D space were considered to provide further insight into the estimation performance for REM construction. The in-depth analysis in 2D space facilitated the determination of the RoIs for each dataset, which were afterwards used for the latter simulation. The variations in the interpolation performance in height and in terms of


This study presents a methodology that combines experimental tests and the finite element method, which is able to analyse the influence of the geometry on the mechanical behaviour of stents made of bioabsorbable polymer PLA (PolyLactic Acid) during their expansion in the treatment of coarctation of the aorta (CoA). Tensile tests with standardized specimen samples were conducted to determine the properties of a 3D-printed PLA. A finite element model of a new stent prototype was generated from CAD files. A rigid cylinder simulating the expansion balloon was also created to simulate the stent opening performance. A tensile test with 3D-printed customized stent specimens was performed to validate the FE stent model. Stent performance was evaluated in terms of elastic return, recoil, and stress levels. The 3D-printed PLA presented an elastic modulus of 1.5 GPa and a yield strength of 30.6 MPa, lower than non-3D-printed PLA. It can also be inferred that crimping had little effect on stent circular recoil performance, as the difference between the two scenarios was on average 1.81%. For an expansion of diameters ranging from 12 mm to 15 mm, as the maximum opening diameter increases, the recoil levels decrease, ranging from 10 to 16.75% within the reported range. These results point out the importance of testing the 3D-printed PLA under the conditions of using it to access its material properties; the results also indicate that the crimping process could be disregarded in simulations to obtain fast results with lower computational cost and that new proposed stent geometry made of PLA might be suitable for use in CoA treatments—the approach that has not been applied before. The next steps will be to simulate the opening of an aorta vessel using this geometry. Coarctation of the aorta (CoA) is a congenital heart disease (CHD) in which a stenosis on the aorta artery occurs. In other words, there is a narrowing in the aorta obstructing the flow of blood. It accounts for 6–8% of all congenital heart diseases ,2,3,4.Among the consequences of CoA, the following can be listed: high blood pressure, breath shortness, tiredness when performing physical exercises, an increase in the pressure difference between the extremities (greater than 20 mmHg), tingling of the extremities, poor limb development, and, in extreme occasions, brain aneurysms ,5,6. EarStudies have presented an incidence of CoA ranging from 1 in 2500  to 1 in The use of metallic stent in newborns or small children, however, is not recommended: as the child grows, the diameter of the aorta would also increase, loosening the stent and allowing its movement inside the artery, leading to thrombosis. Moreover, the stent would have to be re-expanded, increasing the plastic deformation of the stent structure and increasing the likelihood of fracture ,10. AccoAn alternative to metallic stents, and a viable option for use in children and newborns, is the use of bioabsorbable stents, usually made of polymers, specifically PLLA (Poly-L-Lactide Acid) and PLA (PolyLactic Acid) . As thesNumerical methods, especially the finite element method (FEM), have been widely used in the analysis of new cardiovascular equipment and the development and optimization of new stents . This meOne of the steps during surgery for stent insertion is crimping. In this procedure, the stent is compressed into a smaller diameter to be inserted into the catheter: this generates initial plastic deformation and introduces residual stresses. Schiavone et al.  comparedAnother important factor in analysing the performance of a new stent is the ability to expand without recoil. Qiu et al.  studied Due to the problems related to metallic stents and their limitations in paediatric use for the treatment of CoA, the relative occurrence of coarctation in the aorta in young children, and the lack of studies on the structural performance of bioabsorbable stents for the treatment of CoA, this study aimed to develop a methodology that combined experimental testing and the finite element method to analyse the influence of geometry on the mechanical behaviour of a bioabsorbable 3D-printed stent developed by the Centre for Engineering in Circulatory Assistance (CEAC), the Dante Pazzanese Institute of Cardiology (IDPC), during its expansion for the treatment of CoA. This model was developed based on the original prototype and its performance was evaluated in terms of linear-recoil, recoil (elastic recoil), and stress levels.The stent geometry was developed by the Centre for Engineering in Circulatory Assistance (CEAC), the Dante Pazzanese Institute of Cardiology (IDPC). The geometry was made available in CAD format and then prepared in the SpaceClaim software . The stent had a total length of 25 mm, 11 rings in the axial direction, bar-shaped connecting elements, an external diameter of 6.75 mm, and a thickness of 0.25 mm, as shown in Fifteen (n = 15) Type II standard specimens, according to ASTM D638-14, Standard Test Method for Tensile Properties of Plastics , made ofA tensile test was conducted using a Kratos testing machine , with a maximum loading capacity of 2000 kg, a load cell of 2000 kgf, and a loading speed of 5 mm/min.A tensile test to later validate the stent model was performed using five (n = 5) customized 3D-printed PLA stent specimens in a planar condition at a scale of 3.5:1, as shown in maxL) at maximum displacement . The first one aimed to simulate the validation experiment described in A mesh convergence study for the stent was performed using the model without crimping, varying the sizes of the stent elements from 0.16 mm to 0.1 mm, as shown in A first model was developed to simulate the expansion of the stent in the planar condition, during the customized tensile test to validate the stent model, see A second model was developed to simulate the crimping of the stent from its initial diameter of 6.75 mm to 5 mm and its subsequent expansion to a maximum diameter that ranged from 12 mm to 15 mm. These simulations were performed according to the simplifying hypotheses presented by Donik et al. , which cA 3D solid element with a quadratic interpolation function, ten nodes, and three degrees of freedom per node was used for the stent. For the crimper and the balloon, shell elements were used, with four nodes and six degrees of freedom at each node. (1)A radial displacement by the rigid crimper was applied to reduce the stent’s initial diameter from 6.75 mm to 5 mm.(2)The crimper was removed so that the stent could go through the linear-recoil effect.(3)The stent was expanded from 5 mm to a maximum value that ranged from 12 to 15 mm by applying a radial displacement by the balloon.(4)The balloon was removed to measure the elastic recoil.In order to simulate the surgical procedures of inserting a stent into the aorta artery, the following steps were performed:The results obtained by the tensile test with standardized specimens according to 2 of 94.2%.For the construction of the elastic region, the initial nonlinear part of the experiment was not considered as it was related to the initial accommodation of the testing machine. Therefore, only the straight segment between the displacement of 1 mm to 3.7 mm was considered, To find the elastic modulus of the PLA, an average curve from all force vs displacement curves of maxL, was 130.02 mm. The finite element model presented a maximum displacement of 129.8 mm, a difference of 0.16%. The average experimental linear recoil was 36.36%, with an average final stent length, fL, of 82.74 mm. The model presented a linear recoil of 33.76%, with a final displacement, fL, of 12.98 mm  and the experimental results are shown in 12.98 mm , reachinAccording to The von Mises equivalent stress was evaluated to analyse the effect of crimping on the mechanical performance of the stent. Four scenarios were assessed as presented in As can be seen in Coarctation of the aorta (CoA) is a heart disease in which the aorta artery diameter is abruptly reduced in the aorta arc section, decreasing the blood flow and causing motor-physiological underdevelopment of the child ,2,3,4. TOne of the main treatment options for CoA is the use of metallic stents ,6. HowevOne of the crucial steps of the stent insertion surgery is the crimping procedure. In order to insert the stent in the catheter, the stent undergoes extensive compressive loading and deformations. Therefore, any stent project must analyse the stent performance during this procedure. There are several studies in the literature evaluating the crimping behaviour of stents for coronary vessels ,20. HoweConsequently, this study has aimed to develop a methodology that combines experimental testing and the finite element method to analyse the influence of geometry and the crimping procedure on the mechanical behaviour of a new bioabsorbable 3D-printed stent developed by the Dante Pazzanese Institute of Cardiology (IDPC) during the stent’s expansion for the treatment of CoA.Initially, the 3D-printed PLA material was mechanically characterised by standardised tensile tests. The 3D-printed PLA presented an elastic modulus of 1.5 GPa and a yield strength of 30.6 MPa. In a study conducted by Donik et al. , a finitSequentially, a validation experiment of the stent finite element model was performed via a tensile test using customized 3D-printed stent specimens. According to Forbes et al. , the ideIn terms of the influence of crimping on the mechanical performance of the stent, Regarding the equivalent von Mises stress levels for the maximum expansion with crimping c, and wiBioresorbable stents offer an attractive alternative to commercially available metal stents , but speIn terms of the study´s limitations, the coefficient of friction was taken from a study of a coronary artery and not from the aorta due to the lack of such data for the aorta vessel. The balloon was modelled as a rigid surface rather than a flexible balloon, but that approach is widely accepted in the field as it introduces minimal errors and saves computational resources. Another limitation was a comparison of the finite element model’s circular recoil with the experimental linear recoil. As the experimentation procedures for stents are quite complex and data acquisition is difficult, an experiment with customized stent specimens in planar condition rather than in the natural cylinder format was proposed. It was assumed that the circular contraction (recoil) was similar to the linear contraction of the stent. Finally, it was assumed that all materials were homogeneous and isotropic; for 3D-printed specimens, some variation in the mechanical properties was expected.This study developed a methodology combining experimental testing and the finite element to analyse the influence of geometry on the mechanical behaviour of a bioabsorbable stent made of PLA during expansion for the treatment of CoA in children. The 3D-printed PLA was mechanically characterized using a tensile test, obtaining an elastic modulus of 1.5 GPa and a yield strength of 30.6 MPa, which is different from the raw material. With a validated model, it was possible to observe that the crimping process did not affect the stent´s mechanical performance during expansion as the recoil marginally increased; for expansion of diameters ranging from 12 mm to 15 mm, as the maximum opening diameter increased, the recoil levels decreased, ranging from 10 to 16.75%, which suggested that the new proposed geometry made in PLA might be suitable for use in CoA treatments since such studies were not conducted before. Future studies will aim to assess other mechanical properties of the stent, such as foreshortening, inserting an aorta geometry with coarctation in the study, and evaluate the stent’s performance in opening a coarcted aorta.


In conclusion, we say that the follow-up of patients living with HIV in the community does not negatively affect the evolution of the disease as one might think.Community-based organizations (CBOs) are one of the initiatives implemented in Cameroon to improve access to antiretroviral treatment and influence retention in treatment centers. Despite its importance in the decongestion of patients in health facilities, we do not have data to evaluate the overall impact of these organizations. We conducted a two-part observational study. The first part was a descriptive cross-sectional study, where we included patients screened and initiated on anti-retroviral treatment (ART) either by the approved Treatment center (ATC) of Yaoundé Central Hospital (YCH) or by any of our CBOs in 2020. Then, the second part was a retrospective cohort-type study including patients from the 2015 cohort followed up from 2018 to 2020 in order to assess viral load suppression. As regards the first “90”, 7,234 screening tests were performed by CBOs in 2020 out of the 28,302 screening tests registered at the YCH, giving a contribution of 25.6%. From the 7,234 screening tests performed by CBOs, 314 people had an HIV-positive result and 230 (73.34%) were linked to ART through CBOs. From the 28,302 screening tests performed at YCH, 1,089 people had an HIV-positive test, and only 354 (32.50%) were linked to ART, giving a significant difference in the link to ART . Concerning the 3 In 2014 the Joint United Nations Program on HIV and AIDS (UNAIDS) set up a response plan to HIV infection under the name 90-90-90 with the objective that, by 2020, 90% of all people with HIV will be diagnosed, 90% of all people diagnosed will be on treatment, and 90% of people on treatment will achieve viral suppression . In CameStudy design: we carried out a two-part observational study in the various community-based organizations and in the approved treatment center (ATC) of the Yaoundé Central Hospital between July 2020 and July 2021. In the first part, it was a descriptive study including patients screened and put on ART thanks to the six CBOs of the Central Hospital of Yaoundé in 2020. In the second part, it was an analytical study retrospective cohort type.Setting: a community-based organization is an association of people within a community, united for the defense of common interests with common goals well-defined. In Cameroon, Community-based organizations of people living with HIV were recognized by the authorities in 2017, with the objectives of promoting HIV awareness, giving psychosocial support to newly diagnosed patients, providing antiretroviral (ARV) treatments to stable patients defined by the ATC, and preventing new infections through frequent screening in the community ) after 24 months and 70.2% vs 95.5% (RR = 0.52 [0.18-1.54]) after 36 months (6 months .The study we conducted aimed to determine the contribution of CBOs in improving the three UNAIDS “90s”. To do this, we conducted a two-part study for 12 months in the ATC of the Central Hospital of Yaoundé and the CBOs attached to this ATC. In the first part, we describe the patients screened in each of these entities during the year 2020. In the second part, we analyzed data from a cohort of 2017 in order to evaluate and compare the effectiveness of CBOs to the YCH ATC. This study has the merit of being one of the first in our context to assess the role of CBOs in HIV care in Cameroon. However, we note limitations in this study, in particular, the poor matching of patients in the CBO and ATC groups due to the plurality of therapeutic protocols for the same patient. We also highlight the difficulty of finding all the necessary information in the different registers and archives. Regarding HIV screening at the Yaoundé Central Hospital, the CBOs carried out a quarter of tests carried out during the year 2020, giving 25.6%, which is inferior to data from other studies in a rural district of Malawi who found a community counselor contribution of 41% or 21 358 out of 52 510 HIV tests performed at the district and counseling sites . These rAt the end of our study, whose objective was to determine the contribution of CBOs in the improvement of the three 90 of UNAIDS at Yaoundé Central Hospital, it appears that a quarter of patients screened at YCH were carried out thanks to CBOs in 2020. Community-based organizations have a better link to care with more than 2/3 of PLHIV on ART compared to ATC which only initiated less than a third. This study also shows that ART continuation in CBOs does not give poor viral load suppression results.