The properties of the heat-affected zone (HAZ) are reported to have a great influence on the mechanical performance of resistance spot welded advanced high strength steels. Therefore, in the present work, the HAZ of a medium-Mn steel is characterized regarding its microstructure and its mechanical properties depending on the distance to the fusion zone (FZ). In order to obtain the local mechanical properties of the HAZ, samples were heat-treated in a joule-heating thermal simulator using different peak temperatures to physically simulate the microstructure of the HAZ. By comparing the microstructure and the hardness of these heat-treated samples and the HAZ, the local peak temperatures within the HAZ could be determined. Subsequently, tensile tests were conducted, and the austenite phase fraction was measured magnetically on the physically simulated HAZ samples in order to determine the local mechanical properties of the HAZ. As verified by energy-dispersive X-ray spectroscopy, peak temperatures above 1200 °C led to a uniform distribution of manganese, resulting in a predominantly martensitic microstructure with high strength and low total elongation after quenching. Below 1100 °C, the diffusion of manganese is restricted, and considerable fractions of austenite remain stable. The austenite fraction increases almost linearly with decreasing peak temperature, which leads to an increase of the total elongation and to a slight decrease in the strength, depending on the distance to the FZ. Temperatures below 700 °C exhibit hardly any effect on the initial microstructure and mechanical properties. The demands of the automotive industry regarding lightweight construction and simultaneous increase of passenger safety require the application of advanced high-strength steels (AHSS). The research currently focuses on the third generation of these high-performance steels, which are characterized by high strength and acceptable ductility at a significantly lower cost compared to the second generation. This generation consists of quenching and partitioning (Q&P) , transfoDue to the desired establishment of medium-Mn steels for automotive applications, their workability has to be taken into account. In this context, the resistance spot weldability is of particular importance, as this process is the predominant joining technology in the automotive industry . However3 temperature; the intercritical heat-affected zone (ICHAZ), where the peak temperature is between A3 and A1; and the subcritical heat-affected zone (SCHAZ), where the peak temperature is below A1 [In addition to the FZ, the microstructure of the heat-affected zone (HAZ) also influences the mechanical performance of spot-welded AHSS sheets ,20,21,22below A1 ,23,24,25below A1 ,25. Addibelow A1 ,23,26,27below A1 ,29,30. Tbelow A1 . The higThe tensile properties of these zones are of great importance regarding the mechanical performance of the welds and have already been investigated in the literature for a number of AHSS ,26,29,31However, since the diffusivity of manganese is very sensitive to temperature, it can be assumed that the manganese distribution and thus the austenite stability varies strongly over the entire HAZ of medium-Mn steels, which may lead to position-dependent mechanical properties. Therefore, the present work aims to investigate the thermal stability of the austenite in the HAZ as a function of the distance to the FZ and determine its influence on the local mechanical properties. While all the available studies ,26,29,31t is the sheet thickness.The investigated medium-Mn steel has a nominal composition of 0.1 C/6.4 Mn/0.6 Si (wt%). The resistance spot welded steel sheets were uncoated and had a thickness of 1.18 mm. RSW was conducted on a MFDC-1000 Hz pedestal-type welding machine from Nimak , which is equipped with an AutoSpatz regulator  to deliver constant current. As recommended in VDEh SEP1220-2 , F1-16-2The different parts of the HAZ were physically simulated by heat-treating sheets of n = 1) with the geometry illustrated in The mechanical properties of the flat tensile samples , was used for light optical microscopy (LOM). The microstructure of the HAZ was determined at eight positions with a distance of 150 µm. Secondary electron (SE) scanning electron microscopy (SEM) images were obtained on a VERSA 3D from FEI . Electron backscattered diffraction (EBSD) measurements were performed with a step size of 25 nm at a working distance of 15 mm and at an acceleration voltage of 20 kV on the aforementioned SEM, which is equipped with an EDAX Hikari XP  EBSD system. Since EBSD requires a deformation-free surface, the polished cross-sections were additionally ion milled for 15 min with an ArBlade5000 ion milling system from Hitachi . Data evaluation was done with the software package OIM Analysis 7 from EDAX  without any clean-ups. The backscattered electron (BSE) SEM and the energy-dispersive X-ray diffraction (EDX) measurements were conducted on a TESCAN CLARA . EDX measurements were performed at an acceleration voltage of 15 kV, using an X-Max system and the Aztec software from Oxford Instruments .The microstructure of the BM consists of a ferritic  matrix with a considerable fraction of finely dispersed austenite , which is predominantly present in a lath-like arrangement, as shown in the EBSD phase map in The microstructure of the HAZ was determined at eight positions with a distance of 150 µm, as shown in the LOM image in 1 temperature is no longer exceeded. Therefore, the bcc phase consistently represents the soft ferrite. With a fraction of 15.3%, as illustrated in As can be seen in the phase map in The increasing fraction of austenite with increasing distance to the FZ is also reflected in BSE images and EDX measurements in To simulate the temperature profile in the HAZ during RSW, sheets were heated to different peak temperatures as quickly as possible and then rapidly quenched. In order to correlate the microstructure of the physically simulated HAZ samples to the HAZ, their microstructure was investigated by means of EBSD as well. As can be seen in In order to determine the local peak temperatures that were present in the HAZ during welding, the microstructure and the hardness of the physically simulated HAZ samples were compared to the HAZ. The EBSD phase maps of the physically simulated HAZ samples show that the microstructure at the peak temperatures of 1300 °C and 1200 °C is fully martensitic. A minor fraction of 1.2% austenite is detected at a peak temperature of 1100 °C, which corresponds to position 3 in the HAZ. As illustrated in 15) is 33.6%, as determined via tensile testing of a flat tensile sample. Since the peak temperatures of the physically simulated HAZ samples were correlated to the thermal profile of the HAZ, as described in the previous section, the austenite fraction and the local mechanical properties of the HAZ can be determined and are summarized in 15 remains at a more or less constant level between 11.6% and 13.1%. The austenite fraction increases almost linearly from 1.7% at position 3 to 26.9% at position 6. The increasing fraction of austenite leads to a moderate increase in A15 from 11.6% to 15.8% in this zone. YS and TS are determined by the interplay of the strength-increasing mechanism of grain refinement and the strength-decreasing effect of the reduced martensite phase fraction. Both decrease continuously and reach a value of 928 MPa and 1269 MPa, respectively, in the very outer UCHAZ.Although EBSD phase maps allow a qualitative comparison of the austenite fraction, as demonstrated in the previous sections, the extremely fine microstructure results in a systematic underestimation of the austenite fraction by EBSD. Therefore, it was quantified on the physically simulated HAZ samples using magnetic saturation measurements. The magnetic determination of the austenite fraction of the BM revealed a fraction of 27.2%, which illustrates on the one hand the considerable underestimation by EBSD (11.6%) and on the other hand shows that the medium-Mn steel investigated in the present work has a significantly higher austenite fraction than medium-Mn steels in comparable studies ,29. The 15 to 17.1%. At a peak temperature of 700 °C, no martensite is present, and therefore both YS and TS decrease tremendously to 581 MPa and 861 MPa, respectively, and A15 increases sharply to 36.1%. With 32.1%, the austenite fraction reaches a maximum at this position and is noticeably higher compared to the BM. This may be because at this temperature, small amounts of ferrite are still transformed into austenite during heating. In this temperature regime, manganese enrichment may take place, which stabilizes the newly formed austenite. Therefore, no transformation into martensite during the final quenching takes place, and more retained austenite is stable. Lower temperatures do not influence the microstructure, and therefore the austenite fraction and the mechanical performance are equal to those of BM.In the very narrow ICHAZ, which has a peak temperature of approximately 750 °C, the ferrite is only partly transformed into austenite during heating, and the final microstructure after quenching consequently consists of a mixture of austenite, ferrite and some martensite. This leads to a significant reduction in YS and TS to 791 MPa and 1164 MPa, respectively, with a simultaneous still slight increase of ATo sum up, the austenite retention and local mechanical properties of the HAZ strongly depend on the distance to the FZ, which illustrates the importance of investigating it with a small step size. It is shown that the outer FGHAZ with a high phase fraction of austenite does not display the highest strength, due to the grain refinement of the martensite as suggested in the literature , but theIn the present work, the microstructure and local mechanical properties of the HAZ of a resistance spot welded medium-Mn steel were investigated. The presented approach provides a way to obtain the temperature profile of the HAZ with a small step size and without relying on complex FE simulations and the most accurate data input data derived from time- and money-consuming investigations. For this purpose, the entire HAZ was characterized by means of SEM, EBSD and hardness measurements and compared to samples heat-treated on a thermal simulator. The temperature profile of the HAZ could be reproduced, and therefore the determination of the austenite phase fraction and the local mechanical properties of the HAZ was possible. Based on these findings, it can be concluded that the austenite in medium-Mn steels exhibits high thermal stability, which leads to highly position-dependent mechanical properties. It is shown that peak temperatures above 1200 °C lead to a uniform distribution of manganese, resulting in a predominantly martensitic microstructure with high strength and low total elongation after quenching. Below 1100 °C, the diffusion of manganese is inhibited, and a considerable fraction of austenite remains stable. The austenite fraction increases almost linearly with decreasing temperature, which leads to an increase in the total elongation and a slight decrease in the strength with a greater distance to the FZ. Temperatures below 700 °C exhibit hardly any effect on the microstructure and mechanical properties. The microstructural and mechanical characterization conducted in this work, combined with the simulated temperature profile, is intended to be the basis for future efforts to specifically manipulate the microstructure of the HAZ, for example, by means of a post-weld heat treatment, in order to potentially improve the mechanical performance of the entire weld.


In this paper, we study the electrical properties of new hybrid magnetorheological suspensions (hMRSs) and propose a theoretical model to explain the dependence of the electric capacitance on the iron volumetric fraction,  Hybrid magnetorheological suspensions (hMRSs) belong to the magnetorheological suspensions class but differ in that the liquid phase is absorbed into a matrix made up of natural or artificial polymers. hMRSs are materials whose general physical properties and rheological properties, in particular, change a few moments after applying an external magnetic field. These materials, together with magnetorheological suspensions (MRSs) and magnetorheological elastomers (MREs), belong to the class of active magnetic materials. Since the matrix is a liquid for MRSs ,3,4,5,6 When applying a magnetic field, the magnetizable phase from MRSs, MREs, and hMRSs orients along the magnetic field in aggregates with chain or column shapes. The strength of the chains depends on the magnetic properties of the magnetizable phase and the intensity of the external magnetic field ,23,24,25The chain formation when applying a magnetic field and its unraveling when the magnetic field is cancelled depend on the viscoelastic properties of the matrix where the magnetizable phase is dispersed, and the result is a delay in the settlement of physical properties ,3,4,5,6.Based on these considerations, in this work, we explain for the first time the influence of the volumetric fraction of iron (Fe) microparticles and of the gravitational and magnetic fields on the time stability of the dielectric function of hMREs during magnetic excitation. To this aim, we manufactured hMRS samples of cotton fabric doped with MRSs based on silicone oil and Fe microparticles with a diameter of Flat capacitors (MCs) were manufactured from hMRSs with volumetric fractions , silicone oil (SO), and cotton fabric (GB).The diameter of the Fe microparticles (Merck) is At The GB fabric (textile.ro), with a thickness of The manufacturing of hMRSs was performed following 6 steps:Step 1:The volume of Fe microparticles and SO, Step 2:Berzelius glasses were used to mix the Fe and SO components, of Step 3:We homogenized the Step 4:We prepared 3 Petri dishes made from heat-resistant glass Step 5:We placed one of the GB pieces prepared in step 4 and poured either Step 6:We extracted the impregnated GB fabrics from the Petri dishes using tweezers and fixed them above the dishes in order to allow gravitational extraction of excess biphasic liquid. The liquids accumulated in the Petri dishes were measured using a graduated cylinder. Using mechanical techniques and measuring the volume during the procedure, we extracted the liquid solution until we reached When an external magnetic field is applied, the Fe microparticles absorbed in the GB fibers during heating orient along the magnetic field lines. If the magnetic field is switched off, the microparticles return to the fibers.n fabric .In order to obtain flat capacitors  in the Equation (7), we obtain an equation of the first degree, which integrated after t between 0 and t and after z between If we introduce Equation (8) into the formula of capacitance for the flat capacitor, we obtain capacitance The value of In the results from Equation (9), The decreased dditives , ferri-/dditives , carbon dditives , etc., aWhen applying an external magnetic field b, the comoment t ,21.The maximum magnetic force The action Since From Equation (14), we can see that the magnetoconstriction of hybrid hMRSs appears in the presence of a magnetic field.The action At an arbitrary time From Equations (8) and (15), we can calculate thickness In Equation (16), we have two coupling constants: We will try to separate the two coupling constant expressions.Coupling constant As we can see from Equation (17), If we introduce The expression of According to the principle of superposition, size We can see from Equation (18) that From Equation (18), with From Equation (19), we can see that coupling constant B values of the magnetic flux density reached values of 0.00, 0.10, and 0.40 T, with deviations of at most ±5%. For each value of the magnetic field density, we measured the equivalent electric capacitance of MCs in time steps ofThe capacitors , we introduce the values of We can see from In the case where a static magnetic field is superimposed over the gravitational field, we expect that the values of the coupling coefficient If in Equations (21) and (22) we introduce the values In We can also see in From From the definition of the capacitance for a flat capacitor, From Accordingly, the dielectric functions are very stable in time and depend on the amount of microparticles embedded in the textile fabric and are very sensitive to the magnetic flux density. These results are strongly improved compared to hMCs based on cotton fibers soaked with a mixture of silicone oil, carbonyl iron microparticles, and iron oxide microfibers , or to tC B values of the magnetic flux density. Recent results related to shape memory [Hybrid hMRSs were manufactured from cotton fabric fibers and doped with silicone oil and three volumetric fractions of Fe microparticles, e memory  and softe memory ,31 can p


The evolution of the relative content of various phases was monitored over the period of one month: amorphous and crystalline calcite (in 13C spectra), ettringite, aluminum in C-S-H gel, calcium aluminates and calcium hydroaluminates (in 27Al spectra), as well as alite, belite and silicon in C-S-H gel (in 29Si spectra). The retarding effect of the additives on cement hydration at early age was demonstrated. We show that the kinetics of phase assemblage formation is influenced by the acetate ion adsorption on the surface of the anhydrous cement components and hydrated phases. The kinetics of formation of ettringite in the cement paste, depending on the addition of acetic and or sodium acetate, is discussed in the context of potential thaumasite sulfate attack.The hydration kinetics of Portland-limestone cement pastes with organic additives in the form of acetic acid and sodium acetate were studied by using solid-state  Cement-based building materials are among the most used in modern construction. Despite their widespread application and the large amount of information regarding the chemistry of cement pastes ,2, severTo reduce the effect of deleterious external factors and optimize the hydration process and the properties of the obtained cement pastes, various additives based on mineral, organic or multicomponent substances are actively used ,6,7,8. H13C, 27Al and 29Si NMR spectroscopy was selected as the main research tool. The technique allows for obtaining information about the local environment of the investigated nuclei [d nuclei . The advThe main aim of this work was to study the kinetics of the phase assemblage formation in Portland-limestone cement pastes in the presence of acetic acid and its sodium salt, as well as to elucidate the mechanism behind the observed hardening rate and appraise the changes of its strength properties, based on the data obtained. Research on cement hydration that assesses a large number of nuclei with NMR spectroscopy is scarce in the literature. The applied method is supposed to provide detailed structural and quantitative information about the occurring phase changes.C (cement paste without additives), CAA (cement paste with acetic acid) and CSA (cement paste with sodium acetate). The stage of hydration was indicated by the age of the cement paste, which was added to the sample marker.Cement pastes were prepared with a type CEM II/A-L 42.5N Portland-limestone cement , distilled water and p.a. organic additives (acetic acid and sodium acetate). A water-to-cement ratio of 0.45 was used. Organic additives amounted to 3% by cement mass each, both added to the mixing water. Cement pastes were cast in cylindrical plastic molds , where they remained sealed for 24 h. After demolding, the specimens were immersed in distilled water and kept throughout the investigated hydration periods. To study the kinetics of the changes in the phase composition of the pastes at certain ages , about 150 mg of hardened material was scraped off the specimens’ end and placed in paper bags to prevent any further hydration. Such quantity was sufficient for conducting the NMR experiment. In this work, the following nomenclature was used to label the samples: Prior to hydration, the mineralogical composition of the employed cement was determined with X-ray powder diffraction (XRPD) analysis; the results are summarized in 13C, 27Al and 29Si nuclei were studied and characterized by the respective resonance frequencies of 100, 104 and 86 MHz. A probe that is able to rotate the samples at the magic angle to the direction of the constant magnetic field (stabilization accuracy of the rotation frequency ±4 Hz) and stabilize their temperature (temperature stabilization accuracy ±1 °C) was used. Powder samples were loaded on a 4 mm zircon oxide rotor and rotated at a frequency of 12.5 KHz at 20 °C. Tetramethylsilane, for 13C and 29Si nuclei, and 1 M∙D2O AlCl3 solution, for 27Al nuclei, were used as external references.NMR experiments were performed by using an Avance III 400 WB spectrometer  at constant magnetic field of 9.4 T. 13C, 27Al and 29Si nuclei, respectively.All the spectra were recorded by using a single-pulse sequence. The duration of the exciting impulses was 2.5, 4.5 and 2.5 μs; the relaxation delay was 4, 2 and 4 s; the number of scans was 1024, 512 and 1024 for 2R higher than 0.8. Since single-pulse sequence was used to record the NMR spectra, the relative integrated intensities of the signals can be interpreted as mole fractions of the corresponding phase components.Deconvolution of spectra into Gaussian-shape individual components was performed by the least squares method, using the software Origin 9.0.  For all the spectra, the results of approximation were obtained with a coefficient of determination 13C NMR spectrum of the anhydrated cement  clearly distinguished peaks , which are in the form of impurities in alite and belite [(VI). This signal consists of two spectral components: the narrow component at about 15 ppm corresponds to aluminum atoms in Ca3Al2O6 (C3A), and the broad one at about 10 ppm to C4AF [The d belite . The sig to C4AF .27Al NMR spectra of all studied hydrated samples  in anyhydrated alite and belite practically disappears already on the first day of hydration; there is only a weak signal at this age for the CAA and CSA samples. At the same time, a broad asymmetric signal appears at about 65 ppm that can be described as the sum of the two components at 60 and 75 ppm. Both correspond to aluminum atoms Al(IV) in the amorphous cement hydration gel. In fact, the line at about 75 ppm is typical for aluminum incorporation in the C–S–H gel, while the line at around 60 ppm for aluminum atoms in an unstable aluminum silicate hydrate (A–S–H) gel, forming near the surface of clinker grains at conditions of calcium shortage and excess aluminum [In the aluminum . In thisC and CSA samples, a broad asymmetric signal in the region of Al(VI) chemical shifts can be described also by two components: a narrow one at 15 ppm and a broad component, whose chemical shift decreased from 14 to 10.5 ppm from the 1st to the 7th day, and then increased to 14.5 ppm by the end of the investigated time interval. For the CAA sample, there is another narrow component, in this region of the spectrum, at about 11 ppm (see the example in 3) through mono-(CAH10) and dicalcium hydroaluminate (C2AH8) to tricalcium hydroaluminate (C3AH6) [For the  (C3AH6) .29Si NMR spectrum of the anhydrated cement  or of three to four linked silicon tetrahedra  [During the initial stage of hydration of all three cement mixtures, broad unresolved lines appear in the spectrum initially in the range from −75 to −95 ppm, and then the specified range expands to chemical shift values of about −120 ppm (120 ppm) .2 structural elements of the cement paste, in paired (Q2P) and/or bridged (Q2b)silicon tetrahedra in silicate chains, which form the bulk structure of the resulting cement paste [At the later stages of hydration, a narrow line at about −86 ppm appeared in the spectra. This line corresponds to silicon atoms in Qnt paste .13C NMR signals for all three studied samples. It can be seen that the intensities of the lines corresponding to amorphous calcium carbonate sharply decrease at the initial stage of the hydration process for C and CAA samples, and then a slight increase is observed. For the CSA sample, a gradual decrease in the relative proportion of amorphous calcium carbonate is observed. The proportion of calcite increases for all the samples, while that of aragonite decreases, as is especially noticeable for C sample. However, at the end of the studied hydration period (15–34 days), the relative content of calcite and aragonite essentially stabilizes and for CAA sample even slightly reverses. It should be noted that a significant amount of aragonite is observed on the first day of hydration only for C sample.CAA.The increase in the content of the poorly soluble calcium carbonate polymorphs , as noted for all samples, leads to their precipitation in the pores of the hardening cement paste, and this might cause an increase in its strength and a decrease in porosity ,2. The s3 in the CSA sample, on the first day, is much lower than for the other samples. This observation can be attributed to the fact that the acetate ion (CH3COO−) can be adsorbed on the surface of the anhydrated cement microparticles and prevent their hydration [CSA mixture.Evidently, the formation of aragonite in the samples containing organic additives begins only on the second day of hydration, while the fraction of the initial amorphous CaCOydration ,23, and ydration . HoweverCAA sample from 13C NMR spectra, although this compound is resolved in the corresponding 27Al NMR spectra. This is because of the negligible 13C NMR chemical shift difference between AFm phase and other calcium carbonates  that prevents a reliable deconvolution of the overlapped signals [It is worth noting that it is not possible to quantify the amount of calcium monocarboaluminate hydrate (AFm) in  signals .27Al NMR signals for all three studied samples. Considering the observed changes in the intensities of the aforementioned spectral components, it can be concluded that, after the initial dissolution of the aluminate phases of the cement used, a large amount of aluminate hydrate forms, whose quantity gradually decreases. Then the amount of various compounds in the form of C–S–H, A–S–H or C–(A–)S–H gels grows in volume, further gradually decreasing. Finally, a gradual increase in the amount of various calcium hydroaluminates and ettringite is observed.CAA and CSA samples, on the first day, there is an insignificant amount of residual aluminum impurity in C2S and C3S. This can be associated with incomplete hydration of the anhydrous cement particles, due to the adsorption of the acetate ions on their surface.It should be noted that, for the C sample, recrystallization of ettringite practically did not occur, while, in the CAA sample, the amount of the primary and secondary ettringite is noticeably larger than for all the other samples. The presence of acetate groups in the CAA and CSA samples can partially replace the sulfate groups [C sample, resulting in the kinetics observed.The diagrams of e groups . Hence, 3S and C2S [CAA and CSA samples, at the early stages of hydration, an increased amount of aluminate hydrate is observed, which subsequently, with an increase in the calcium content, gradually transforms into the more stable C3AH6 phase.Since the surface of the aluminum-containing clinker phases is more electronegative than that of C and C2S , their dCAA sample may act as a risk factor for sulfate corrosion.Moreover, aluminum actively passes into the crystalline phases of ettringite and calcium hydroaluminate; hence, its content in the amorphous C–(A–)S–H phase decreases. It should be noted that the increased ettringite content observed in the 29Si NMR signals for all the three studied samples. When analyzing the change in the relative integrated intensities of the observed spectral components during hydration, we observed that the mass fraction of the silicate-containing clinker phases gradually decreases for all samples, while the mass fraction of the C–(A–)S–H phase increases proportionally, as well as the fraction of paired Q2 terahedra. It should be noted that the Q2 tetrahedra resolved in the spectrum appear on the first day for the CSA sample, on the second day for the C sample, and only on the third day for the CAA sample. Moreover, for the CAA sample, the spectral component, which is visually distinguishable from the baseline and is characteristic for Q3 and Q4 structural elements, also appears only on the second day of hydration.1, Q2 and Q3 structural elements [2 tetrahedra increases, and this increase can correspond to an increase in the length of silicate chains, consisting of paired silicate tetrahedra. The presence of such phase corresponds to an increase in strength of the cement matrix. The formation of this phase for the CAA sample is observed at later stages of hydration.These observations, along with the fact that no resolved peaks arise from other characteristic Qelements , may indCAA sample as compared to the other two.It should be noted that, during cement hydration, a relative redistribution of the amounts of alite and belite occurs . For allCAA sample, the remaining amount of such phases is slightly less than for the other two samples; the addition of acetic acid leads to the involvement of a larger amount of alite in the formation of the C–(A–)S–H gel. That is, at the later stages of the hydration process of the CAA paste a smaller amount of alite remains anhydrated, and, thus, it is more effectively transformed to amorphous hydrate phase, affecting the strength properties of the hardened material.Over the entire investigated time interval, the silicon-containing anhydrous phases did not completely hydrate. It should be noted that, in the 29Si nuclei.In contrast to X-ray studies, one of the advantages of the NMR method is the ability to directly observe the signals of the nuclei both in the crystalline and amorphous local environments. As a result, in this work, it was possible to trace the time dependences of a set of chemical phases in the studied cement pastes. Despite the natural difficulty in obtaining unambiguous deconvolution of strongly overlapped signals of some cases, it was possible to identify the main components the presence of which is assumed in the chemistry of cementitious materials, including the amorphous phases, especially the crucial ones containing Considering all the above, it can be deduced that the addition of acetic acid and sodium acetate changes the kinetics of the cement paste phase composition during the hydration process. Adsorption of the acetate ion on the surface of the anhydrated and hydrated phases has a significant effect on the hydration process when the studied organic substances are added in the mixtures. Moreover, the presence of sodium ions slightly increases the alkalinity of the pore solution, partially reducing the efficiency of such adsorption.It can be concluded that the addition of 3% acetic acid or sodium acetate, by cement mass, to the cement paste hindered the initial stages of the hydration process. The addition of sodium acetate led to the formation of a large amount of poorly soluble forms of calcium carbonate and a significant increase in the amount of polymerized silicon-containing phases.Concerning the sulfate degradation of the cement paste, we see that the addition of acetic acid led to the development of favorable conditions for the formation of ettringite; in contrast, the addition of sodium acetate slightly slowed down this process. Thus, in the future studies, it would be interesting to investigate whether sodium acetate is a useful additive for improving the durability of hardened cementitious materials against sulfate attack. As only cement pastes were investigated in this work, further applied studies in this field are needed.


Acidosis and its associated pathologies predispose patients to develop cardiac arrhythmias and even cardiac arrest. These arrhythmias are assumed to be the result of membrane depolarization, however, the exact mechanism of depolarization during acidosis is not well defined. In our study, the model of quantum tunneling of protons is used to explain the membrane depolarization that occurs during acidosis. It is found that protons can tunnel through closed activation and inactivation gates of voltage-gated sodium channels Nav1.5 that are present in the membrane of cardiac cells. The quantum tunneling of protons results in quantum conductance, which is evaluated to assess its effect on membrane potential. The quantum conductance of extracellular protons is higher than that of intracellular protons. This predicts an inward quantum current of protons through the closed sodium channels. Additionally, the values of quantum conductance are influential and can depolarize the membrane potential according to the quantum version of the GHK equation. The quantum mechanism of depolarization is distinct from other mechanisms because the quantum model suggests that protons can directly depolarize the membrane potential, and not only through indirect effects as proposed by other mechanisms in the literature. Understanding the pathophysiology of arrhythmias mediated by depolarization during acidosis is crucial to treat and control them and to improve the overall clinical outcomes of patients. In the human body, acid-base balance is under tight regulations because the function of cells requires normal plasma pH levels, and only a minimal disturbance in the blood acidity could affect cells significantly and render them unable to work. Normal blood pH values range between 7.36 to 7.44 and acidemia is defined as extracellular pH less than 7.36. Hence, acidosis is the pathological process that leads to a state of high hydrogen ions (protons) concentration in the plasma (acidemia) if left untreated ,2.Acidosis harmfully affects different body systems including the cardiovascular system, nervous system, gastrointestinal system, and others. Here, our focus is the harmful effects of acidosis on the electrical cardiac functions. Acidosis is considered to be an arrhythmogenic factor that predisposes the heart to develop different arrhythmias including ventricular fibrillation, and it can slow the electrical conduction through the atrioventricular node ,4,5. Mor+/K+ ATPase is indirectly inhibited because acidosis inhibits the cellular metabolism and hence production of ATP, but this seems unlikely to happen because first acidosis does not inhibit the metabolism rigorously, and secondly because changes in membrane potential were noticed during times of normal intracellular ATP levels [+2 concentration is increased, because of this, Na+/Ca+2 exchanger may be activated or non-specific intracellular cation currents might be generated, but the fact that the currents generated are decreased by the rising intracellular Na+ concentrations that happens during acidosis weakens this theory [+ currents during times of acidosis, but this mechanism is disproved somehow because firstly, an increase in intracellular Ca+2 during acidosis as mentioned earlier activates calcium activated potassium channels, thus hyper-polarizing the membrane; secondly, increased intracellular sodium concentrations during acidosis might activate sodium activated potassium channels, therefore hyperpolarizing the membrane potential [+/K+ ATPase directly, but the gap is that this is difficult to be achieved by merely inhibiting the Na+/K+ ATPase alone [+2 which provokes inward depolarizing currents mainly by activating the Na+/Ca+2 exchanger, and this mechanism is opposed by the fact that the concentration of intracellular sodium ions increases during acidosis and this inhibits the currents mediated by Na+/Ca+2 exchanger [The exact mechanism of how acidosis causes depolarization is still not well understood and requires further investigation to fill the knowledge gap . HoweverP levels . The secs theory . The thiotential . The fouse alone . (2) Earse alone . (3) Delxchanger .Accordingly, it seems that these mechanisms are opposed by other mechanisms that counteract the depolarization. Furthermore, none of these mechanisms focus on the protons themselves, which are the direct cause behind the decrease in pH and acidemia. Additionally, the different phases of depolarization cannot be unified into one comprehensive mechanism. Therefore, finding other mechanisms that may underlie the pathophysiology of acidosis-induced depolarization and arrhythmias is warranted to improve the clinical outcomes of acidosis.The present study aims to propose a possible explanation of the mechanism by which acidosis leads to depolarization by using the quantum tunneling model of ions ,10,11 anQuantum mechanics is the field of physics that pays attention to atomic and subatomic particles’ behavior. The quantum tunneling is the phenomenon where a wavefunction of a particle can propagate through a potential barrier and that its energy is higher than the energy of the particle. The propagation through the barrier depends exponentially on the barrier’s energy, barrier’s length, particle’s mass, and particle’s energy . This quIn the present study, the model of quantum tunneling of protons through the cardiac voltage-gated sodium channels will be used to show that protons can tunnel through the closed channels and depolarize the membrane potential. The quantum mechanism is different from the previously mentioned mechanisms because the quantum mechanism will focus on the protons themselves as a direct contributor to the depolarization, unlike other mechanisms, which attribute this effect to the indirect effects of acidosis on channels and other ions such as sodium ions, potassium ions, and calcium ions. Other qualities of this quantum model will be discussed later.Evidence of proton leak through voltage-gated ion channels is established. A study on a patient with severe mixed phenotype who presented with conduction disease and dilated cardiomyopathy demonstrated that a proton leak through mutated Nav1.5 mutation (R219H) is responsible for acidifying the cardiac myocytes as well as the development of arrhythmias and dilated cardiomyopathy . AdditioQT is the tunneling probability, m is the mass of the particle (Kg), U(x) is the energy of the barrier with respect to the position of particle x, KE is the kinetic energy of the particle, and x2–x1 is the region where the energy of barrier is higher than the energy of the particle.The probability of quantum tunneling through a potential barrier is calculated after solving the Schrodinger equation and finding the wave-function of the particle and then applying the Born’s rule to find the probability of finding the particle at a certain position. Therefore, the equation that calculates the tunneling probability is :(1)TQ=e−w is the width or the length of the gate and its unit is meter (m).The model of quantum tunneling will be applied on protons and sodium ions while passing through the closed activation or closed inactivation gate of the voltage-gated sodium channels that are present in the membrane of cardiac cells. In the previous works, the full derivation of the tunneling probability equation of ions through the gate was discussed and explained extensively. Therefore, in this study we will use the final form of the derivation ,11:(2)TQThe voltage-gated channels form an activation gate or inactivation gate at the intracellular end of the membrane. Therefore, extracellular cations that come from outside will pass through the membrane potential (negative inside with respect to outside) to obtain kinetic energy equivalent to 4×10−20J ,19. On t4×10−20J ,22. Ther(E) refers to extracellular ions, (I) refers to intracellular ions, q is the charge of ion, mV is the membrane potential, BK is the Boltzmann constant (T is the body temperature (310 K). Our model will be applied on protons and sodium ions, and both have charge equal to the charge of electron As a result, the tunneling probability for extracellular cations and intracellular cations, respectively, are:q is charge of the ion, h is the Planck constant (QT is the tunneling probability. The unit of quantum conductance of single channel is Siemens (S).The conductance of single channel is an important property of the channel that determines the electrical features of excitable tissues. In the context of the quantum model, we will deal with quantum conductance of a single channel CQ ,19:(5)CQD is the density of channels (channels/cm2), and 2.Eventually, we will consider the quantum membrane conductance otential ,10:(6)MCThe membrane conductance due to open channels MC is :(7)MC=D×C is constant, however, the quantum conductance of single channel Here, the difference is that the conductance of single channel (when it is open) (E) indicates extracellular ions, (I) indicates intracellular ions, (K) refers to potassium ions, (Na) refers to sodium ions, (H) refers to protons (hydrogen ions), F is Faraday’s constant , R is the gas constant (8.31 J/Kmol), T is body temperature (310 K), and mV is resting membrane potential.To assess the impact of quantum tunneling of protons and sodium ions on the resting membrane potential, the quantum version of Goldman–Hodgkin–Katz (GHK) equation will be used ,10:(8)[KIn the present paper, quantum conductance of protons and sodium will be studied for the purpose of comparison.2 [2 [Before considering the quantum conductance of protons and sodium ions, the resting membrane potential =0.087 V ,8 , the tunneling probability of extracellular protons is calculated by the following equation:On the other hand, the tunneling of probability of intracellular protons is calculated by the following equation considering Equation (4):From Equation (2), we took In this section, the focus is on the energy of gate he right . Therefohe right . Therefothe left . Thus, imV is chosen to be the resting membrane potential The gating charge of Nav1.5 channels is ing=3.8e  and the 0.0326 V . Therefoge is 5e . On the 2 [In the following graphs, these setting values will be substituted in the equations unless we set different values for evaluation: L=1.5 m , Vm=0.08=0.087 V , n=1 [10According to Equations (9) and (10), the common logarithms of tunneling probability of extracellular protons L  in Equation (9) to produce three plots. Each graph has its own setting values according to the factor that the graph, which is plotted three times, is based on. This style of evaluation will be applied to all graphs of this study. Additionally, this style of evaluation is used to facilitate the understanding of the influence of gate length, membrane potential, gate location, and the channels density on the tunneling probability and quantum conductance. Additionally, this style of evaluation of setting certain reasonable values of the variables helps to obtain consequent numerical values that can aid in the understanding of the behavior of the relationship and can be used for the purposes of comparison for different ions at the same setting values. Moreover, graph (d) of Above each graph in the previous figure, we put setting values at which the evaluation of the relationship is based on. For example, in graph (a) of By considering Equation (3), the tunneling probability of extracellular sodium ions is calculated by the following equation:By considering Equation (4), the tunneling probability of intracellular sodium ions is calculated by the following equation:The same mathematical manipulations made on the equation of tunneling probability of protons are made on the equation of tunneling probability of sodium ions. The number 35 emerges as a result of the following calculations: According to Equations (11) and (12), the common logarithms of tunneling probability of extracellular sodium ions By considering Equation (5), the quantum conductance of a single channel for extracellular protons is calculated by the following equation:On the other hand, the quantum conductance of a single channel for intracellular protons is calculated by the following equation considering Equation (5):The unit of quantum conductance of a single channel is (S).The constant According to Equations (13) and (14), the relationship between the common logarithms of quantum conductance of a single channel for extracellular protons By considering Equation (5), the quantum conductance of single channel for extracellular sodium ions:On the other hand, the quantum conductance of single channel for intracellular sodium ions is calculated by the following equation considering Equation (5):The unit of quantum conductance of a single channel is (S).The constant According to Equations (15) and (16), the relationship between the common logarithms of quantum conductance of single channel for extracellular sodium ions By considering Equation (6),the quantum membrane conductance of extracellular protons can be calculated by the following equation:On the other hand, the quantum membrane conductance of intracellular protons can be calculated by the following equation considering Equation (6):2.The unit of quantum membrane conductance is mS/cm2.According to Equations (17) and (18), the relationship between the common logarithms of quantum membrane conductance of extracellular protons By considering Equation (6), the quantum membrane conductance of extracellular sodium ions can be calculated by the following equation:By considering Equation (6), the quantum membrane conductance of intracellular sodium ions can be calculated by the following equation:2.The unit of quantum membrane conductance is mS/cm2.According to Equations (19) and (20), the relationship between the common logarithms of quantum membrane conductance of extracellular sodium ions Here, the quantum version of GHK equation, as in Equation (8), is used to assess the impact of quantum tunneling of protons on the resting membrane potential without considering the quantum tunneling of sodium ions:12.71+10−en 6–7.4 . The pHEThe value 2.71 results from the following calculations by substituting the values of physiological parameters in Equation (8): The minus sign is inserted in the mathematical term According to Equation (21), the resting membrane potential is assessed with regard to the energy of gate For the purpose of comparison, the quantum version of GHK equation, as in Equation (8), is used to assess the effect of quantum tunneling of sodium ions on the resting membrane potential without considering the quantum tunneling of protons:Here, 5.51 results from the following calculation: According to Equation (22), the resting membrane potential is assessed with regard to the energy of gate On the other hand, the classical version of GHK equation is used to evaluate the effect of the transport of protons through open channels. The classical version of GHK equation does not include the quantum conductance of protons or sodium ions:By substituting the values of physiological parameters in Equation (23):×10−12 S ,27. Moreuted 252 .(25)2.7The value According to Equation (25), the resting membrane potential can be assessed under the influence of classical transport of protons through open sodium channels. See The present work proposes a quantum model to explain the acidosis-induced depolarization and the consequent cardiac arrhythmias. The model states that protons are able to pass through the closed voltage-gated sodium channels via quantum tunneling. According to the quantum model, quantum tunneling of protons results in a quantum current that passes through the channel and hence there will be a quantum conductance of single channel and quantum membrane conductance. Therefore, quantum tunneling is the cardinal feature that provides the outcome of quantum conductance. The model is applied on the cardiac sodium channels Nav1.5 specifically at the activation and inactivation gate. Both activation and inactivation gates possess an energy barrier to prevent the passage of ions when these gates are closed. During acidosis, the energy barriers of the gates are affected. It was found that there is a right shift in the activation and inactivation curve under the effect of acidosis and this means that the half activation and half inactivation voltages increase . When thWe investigate, mathematically, the quantum tunneling probability and quantum conductance of protons and sodium ions over a range of mV. See According to the graphs of quantum tunneling in This discrepancy in tunneling probabilities between extracellular and intracellular ions results in a quantum gradient that favors the flow from the extracellular compartment to the intracellular compartment. Additionally, it seems that the discrepancy in tunneling probabilities for protons is less than the discrepancy for sodium ions, however, protons have higher tunneling probabilities than sodium ions because a proton’s mass is less than a sodium ion’s mass. See Additionally, the length of the gate is an important factor that inversely affects the tunneling probabilities, hence as the length increases, the tunneling probability decreases as presented in the graphs (a) and (d) of L . The evaluation is made by setting The graph (a) of mV = 0.087 V, mV = 0.077 V, and mV = 0.067 V). The evaluation is made by setting The graph (b) of The graph (c) of L . See The graph (d) of L . The evaluation is made by setting The graph (a) of m = 0.087 V, Vm = 0.077 V, and Vm = 0.067 V). The evaluation is made by setting The graph (b) of The graph (c) of L . See The graph (d) of The tunneling probability of extracellular ions (protons and sodium ions) is higher than the tunneling probability of intracellular ions (protons and sodium ions) at the same setting values;The tunneling probability of extracellular and intracellular protons is higher than the extracellular and intracellular sodium ions at the same setting values;As the energy of the gate increases, the tunneling probability of ions (protons and sodium ions) decreases;As the gate length increases, the tunneling probability of ions (protons and sodium ions) decreases;As the absolute value of membrane potential (negative inside with regard to outside) increases, the tunneling probability of extracellular ions increases;As the location of gate (n) increases, the value of membrane potential available for the kinetic energy of extracellular ions decreases and thus their tunneling probability decreases.By comparing the tables of quantum tunneling of protons and sodium ions, it is clear that:The previous discussion is also valid on quantum conductance of a single channel and the quantum membrane conductance because they are dependent on the tunneling probability, but the quantum membrane conductance is also dependent on the number of channels available for tunneling and these channels must either be in closed form (activation gate is closed) or inactivated (inactivation gate is closed) so that the principle of quantum tunneling can be applied, because when the channel is open, ions passage is predicted according to the classical mechanics.Classically, when the voltage-gated sodium channel Nav1.5 is open, the single channel conductance for sodium ions is ×10−12 S ,27, and ×10−12 S , it is eL . The evaluation is made by setting The graph (a) of m = 0.087 V, Vm = 0.077 V, and Vm = 0.067 V). The evaluation is made by setting The graph (b) of The graph (c) of L . See The graph (d) of By comparing the tables of quantum conductance of single channel for protons, it is clear that they do not have a single value of conductance as in the classical model, but a spectrum of continuous values spanning from the values calculated at L . The evaluation is made by setting The graph (a) of m = 0.087 V, Vm = 0.077 V, and Vm = 0.067 V). The evaluation is made by setting The graph (b) of The graph (c) of L .See The graph (d) of By comparing the tables of quantum conductance of single channel for sodium ions, it is clear that they do not have a single value of conductance as in the classical model, but a spectrum of continuous values spanning from the values calculated at The previous six conclusions applied to the quantum tunneling probability of protons and sodium ions are also applied to the quantum conductance of a single channel of protons and sodium ions.Furthermore, protons and sodium can achieve quantum membrane conductance higher than the conductance achieved classically by opening the same number of channels available for tunneling. This observation, as said before, is prominent at lower values of gate energy L . The evaluation is made by setting 2, and n = 1. See The graph (a) of m = 0.087 V, Vm = 0.077 V, and Vm = 0.067 V). The evaluation is made by setting 2, and n = 1. See The graph (b) of 2. See The graph (c) of 2, 2, and 2). The evaluation is made by setting The graph (d) of L . The evaluation is made by setting 2. See The graph (e) of 2, 2, and 2). The evaluation is made by setting The graph (f) of 2 at 2, 2 at 2, and 2 at 2. By comparing these values with the values in tables of protons, it is clear that both extracellular protons at 2.5 J and intracellular protons at 1 J obtain quantum membrane conductance higher than the classical membrane conductance. This is true for all the values at 2.5 and 1 J. These higher quantum membrane conductance values continue to decrease until reaching at 2 and 0.005 mS/cm2, respectively) at the resting state. This predicts the ability of protons to depolarize the resting membrane potential via quantum tunneling since extracellular protons have higher quantum conductance than the intracellular protons and the intracellular to extracellular concentration ratio of protons, which is 10, is lower than the ratio of potassium ions, which is 140/4 = 35.The classical membrane conductance of protons can be calculated by multiplying the conductance of single channel L . The evaluation is made by setting 2, and n = 1. See The graph (a) of m = 0.087 V, Vm = 0.077 V, and Vm = 0.067 V). The evaluation is made by setting 2, and n = 1. See The graph (b) of 2. See The graph (c) of 2, 2, and 2). The evaluation is made by setting The graph (d) of L . The evaluation is made by setting 2. See The graph (e) of 2, 2, and 2). The evaluation is made by setting The graph (f) of 2 at 2, 2 at 2, and 2 at 2. By comparing these values with the values in tables of sodium ions, it is clear that both extracellular sodium ions at 2.5 J and intracellular sodium ions at 1 J can obtain quantum membrane conductance higher than the classical membrane conductance. This is not true for all the values at 2.5 and 1 J because other factors such as gate length, membrane potential, and the gate location modulate the values of quantum membrane conductance. These high quantum membrane conductance values continue to decrease until reaching at 2 and 0.005 mS/cm2, respectively) at the resting state. This predicts the ability of sodium ions to depolarize the resting membrane potential via quantum tunneling, since extracellular sodium ions have higher quantum conductance than the intracellular sodium ions and the extracellular concentration of sodium ions is higher than their intracellular concentration.The classical membrane conductance of sodium ions can be calculated by multiplying the conductance of single channel The previous six conclusions applied to quantum tunneling probability and quantum conductance of single channel are also applied to the quantum membrane conductance of protons and sodium ions.In the previous discussion, we focused on the tunneling probability and quantum conductance because conductance is a crucial factor that affects membrane potential. According to the GHK equation, membrane potential is influenced by two main factors: (1) the ion’s concentration and (2) the ion’s conductance or permeability. When the quantum conductance is inserted into the classical version of the GHK equation, we obtain a quantum version. This equation calculates the membrane potential at resting state, at which the channels are in a closed state or an inactivated state. The percentages of these states depend on the membrane potential. As the membrane potential depolarizes, the number of inactivated channels increases and the number of closed channels (activation gate is closed) decreases. However, both states can be used to apply the model of quantum tunneling of protons. This equation can give reflection about the degree of depolarization according to certain values of concentration and conductance. Hence, it is used in this study to assess the effect of quantum conductance of protons on the membrane potential and the degree of depolarization induced by the quantum tunneling of protons. It is obvious from To make the differences between protons and sodium ions clear in terms of membrane depolarization, a numerical comparison based on In the following tables, we are going to use two quantities to make the results clear and comprehensible. These two quantities are the point of curving The following tables will investigate the properties of protons to depolarize the membrane potential. Moreover, the average rate of change will be calculated from the point of curving to the end of the graph, which is at The average rate of depolarization for protons can be calculated by the following equation:2, and n = 1. See The graph (a) of From 2, and n = 1. See The graph (b) of L increases, the point of curving L and the depolarization occurs at higher values of energy of the gate. This is manifested as a shorter high plateau at lower values of gate length L, see L increases, the membrane potential becomes more depolarized at L increases, the average rate of depolarization increases. In other words, as the protons become more sensitive to the drop in the energy of the gate , the average rate of depolarization becomes slower.From 2, 2, and 2) and by setting The graph (c) of From 2. See The graph (d) of From In the following tables, we are going to investigate the depolarization induced by the quantum tunneling of sodium ions. However, it seems obvious from The average rate of depolarization for sodium ions can be calculated by the following equation:2, and n = 1. See The graph (a) of L increases, the point of curving L and the depolarization occurs at higher values of energy of the gate. This is manifested as a shorter plateau at lower values of gate length L, see L increases, sodium ions reach the 0 V at lower values of energy of the gate. Moreover, as the value of gate length L increases, the average rate of depolarization increases. In other words, as sodium ions become more sensitive to the drop in the energy of the gate , the average rate of depolarization becomes slower.From 2, 2, and 2) and by setting The graph (b) of From 2. See The graph (c) of From By comparing the tables of depolarization for both protons and sodium ions, it is clear that protons are more sensitive than sodium ions to the drop in the energy of the gate. This is evident by the higher values of point of curving for protons 2, 2, and 2). The evaluation is made by setting the permeability ratio The graph of From Even though our study focuses on the resting state with its corresponding conductance values of sodium and potassium ions, the depolarization induced by quantum tunneling is also valid during the repolarization phase and after repolarization because protons and even sodium ions showed a strong tendency to depolarize the membrane potential due to the significant quantum conductance as presented in the mathematical graphs in the results section. Therefore, we use the GHK equation to give an insight about the ability of protons to depolarize the membrane potential when the closed or inactivated channels are available.In this context, we propose that gating pore currents of protons (omega currents) might be quantum currents through closed channels and the effects of mutations of S4 segments and acidosis are similar and result in decreasing the energy barrier of closed gates, enhancing the quantum tunneling of protons and other ions. Additionally, the ability of protons to pass through closed voltage-gated proton channels  supportsTo sum up, acidosis augments the quantum tunneling of protons resulting in a positive inward current that depolarizes the membrane potential. This state of membrane depolarization increases the tendency of cardiac arrhythmias or even cardiac arrest depending on the degree of depolarization. See


By means of X-ray computed microtomography (XCMT), the existence of a developed porous structure with an average pore diameter of ~3.5 μm and pore content of ~1.1 vol.% has been revealed in unirradiated polytetrafluoroethylene (PTFE). It has been found that the combined action of gamma radiation (absorbed dose per PTFE of ~170 kGy) and high temperatures (327–350 °C) leads to the disappearance of the porous structure and the formation of several large pores with sizes from 30 to 50 μm in the bulk of thermal-radiation modified PTFE (TRM-PTFE). It has been established by X-ray diffraction (XRD) analysis that the thermal-radiation modification of PTFE leads to an increase in the interplanar spacings, the degree of crystallinity and the volume of the unit cell, as well as to a decrease in the size of crystals and the X-ray density of the crystalline phase in comparison with the initial polymer. It is assumed that the previously-established effect of improving the deformation-strength and tribological properties of the TRM-PTFE can be due not only to the radiation cross-linking of polymer chains but also to the disappearance of the pore system and to the ordering of the crystalline phase of PTFE. High-temperature radiation modification of polytetrafluoroethylene (PTFE) is a promising method for overcoming the disadvantages of this material-such as cold brittleness, porosity, and low radiation resistance ,2. It waA common drawback of cited studies ,3,4,5,6 The lack of estimates of the density of cross-links, which is a key parameter characterizing the efficiency of radiation cross-linking processes, excludes the comparison of experimental data with the predicted efficiency of the high-temperature irradiation treatment of PTFE ,3,4,5,6.At the same time, it is known that traces of the crystalline phase of PTFE can exist in the melt up to a temperature of 400 °C and that the processes of radiolytic gas evolution and depolymerization under γ-irradiation of PTFE can proceed for up to 500 °C ,9. ThereIt has been shown that, under the conditions of simultaneous cross-linking and crystallization processes, the cross-link density can be estimated from the average crystallite size . Then, iThe aim of this study is to establish the nature of the effects of improving the deformation-strength and tribological properties, increasing the radiation resistance of PTFE under the combined action of ionizing radiation and high temperatures by studying the microstructure and crystalline phase of the initial and thermal-radiation modified polymer.For the manufacture of TRM-PTFE and control samples, PTFE grade F-4 (Soviet State Standard 10007-80) produced by JSC “HaloPolymer Kirovo-Chepetsk”  was used in the form of cylindrical rods 25 mm in diameter and 250 mm in height, which were obtained by sintering powdered PTFE obtained by emulsion polymerization.Disks with a diameter of 25 mm and a thickness of 2 mm, which were cut from cylindrical rods of the initial and TRM-PTFE, were used for X-ray diffraction studies. The X-ray computed microtomography study of the microstructure of initial and TRM-PTFE was carried out on cylindrical polymer samples with a diameter of 3 mm and a height of 6 mm.60Co isotope (mean energy 1.25 MeV) was implemented in a radiation-chemical apparatus made of stainless steel and located in the working chamber of the unique scientific installation (USI) “Gammatok” at the Institute of Problems of Chemical Physics, Russian Academy of Science  ¤ 1/hkld2  × V=0.8 of PTFE  and NA i of PTFE .L by a factor of 3.82 relative to initial PTFE is observed , in comparison with the data given in Apparently, the value lated in , is overc value established in [a = 5.59 Å, c = 16.88 Å, γ = 119.3°) [However, the large lattice constant ished in  is in go 119.3°) . Then, ihkl = 100 in the X-ray spectra of PTFE. Therefore, it can be assumed that the previously obtained estimates of the large lattice constant c and the X-ray density of PTFE confirm this fact [It should be noted that the presence of crystals in the triclinic conformation in the crystalline phase of PTFE, which determine its composition in the temperature range below a phase transition temperature of 19 °C, can significantly increase the density of PTFE . At the his fact .cρ of PTFE, which was confirmed experimentally  ordering the crystal structure of polytetrafluoroethylene (PTFE) as a result of a decrease in the content of crystals with defects; (ii) the disappearance of the system of micropores formed during the preparation of the polymer sample. In addition, the influence of ionic particles in the course of radiation crosslinking of PTFE in the melt cannot be ruled out. Let us take a closer look at these effects:(i) The mechanisms of reactions proceeding under the influence of ionizing radiation and reactions excited thermally are different . The forThere are different points of view on the course of changes in the microstructure of PTFE during high-temperature radiation treatment for example, the decisive role of crosslinking processes is discussed in . HoweverIn particular, a decrease in the absorbed dose corresponding to the onset of the PTFE decrystallization process from 3 MGy to 1 MGy observed with an increase in the temperature of gamma irradiation from 303 to 453 K may be due to acceleration of the depolymerization of the polymer at high temperatures and the enhancement of chain branching .The results obtained in this article are consistent with the second hypothesis. However, in addition to conclusions , it shou(ii) Radiation-induced formation of a system of closed pores is one of the main radiation effects that leads to a change in the structure of condensed media ,67,68,69This is confirmed by the results of a study by the method of X-ray computer microtomography of radiation-induced changes in the characteristics of the porous structure in foamed polyurethane samples, gamma-irradiated to various doses at room temperature . It is s15–1018 to 1012 cm−3. It was concluded that with an increase in the irradiation temperature, the mechanism of pore formation changes from homogeneous to heterogeneous. It was also noted [At first glance, the results ,68,69 coso noted  that theThe data obtained in this study on the regularities of the behavior of the porous structure of PTFE under the conditions of polymer irradiation in the melt are in full agreement with the conclusions ,71. Thus(iii) It is assumed in studies ,3,4,5,6 Apparently, it is impossible to describe the contribution of radiation and temperature factors to the development of radiation-induced processes in PTFE within the framework of one theoretical model. The above discussion of the effect of temperature on various radiation-induced processes developing in the PTFE melt during radiation modification shows that for each type of such processes it is necessary to take into account the contribution of temperature and radiation-chemical reactions separately. Obviously, it is necessary to carry out further studies of the regularities of changes in the structure and radiation-chemical processes in PTFE depending on the irradiation temperature.The study of changes in the microstructure and structure of the crystalline phase of PTFE caused by the combined action of γ-radiation and high temperatures has provided the following conclusions:(i) The existence of a developed porous structure with an average pore diameter of ~3.5 μm and a pore volume content of ~1.1% in PTFE has been revealed by the technique of X-ray computed microtomography. The thermal-radiation modification of PTFE leads to the disappearance of the porous structure and the formation of several large pores with sizes from 30 to 50 μm.(ii) A comparative study of the diffraction patterns of the initial polymer and TRM-PTFE has been carried out by the method of X-ray diffraction analysis. It has been established that the combined action of γ-radiation up to a dose of 173 kGy and high temperatures leads to an increase in interplanar spacings, the degree of crystallinity, and volume of the unit cell and to a decrease in the size of crystals and the X-ray density of the crystalline phase in TRM-PTFE in comparison with the unmodified polymer. All found differences have been explained under the assumption that the phase transition in the crystalline phase of PTFE at 19 °C is smoothed; as a result, crystals of triclinic and hexagonal conformations can be present in PTFE at room temperature.(iii) Thermal-radiation modification leads to the removal of crystals in the triclinic conformation, to an increase in the contribution of hexagonal crystals, and to local ordering of the TRM-PTFE structure. Satisfactory agreement between the calculated and experimentally determined values of the density of the initial polymer and TRM-PTFE confirms the assumption about the presence of two types of lattices in the crystalline phase of PTFE(iv) The effect of improving the deformation-strength and tribological properties of PTFE caused by the combined action of ionizing radiation and high temperatures is due not only to the processes of radiation cross-linking of polymer chains but also to the disappearance of the pore system and the ordering of the crystalline phase of PTFE. Radiation crosslinking processes can affect the growth and size of the resulting PTFE crystals.(v) Averaging of the properties of PTFE under the combined action of the high temperatures and gamma-irradiation is the main reason for a significant increase in the radiation resistance of the thermal-radiation-modified polymer.


The observational design is nomothetic, punctual, and multidimensional. A total of 176 ball screens situations have been analyzed for the men's category and 118 for women's category, corresponding to three different teams of each gender playing in the highest competition level in Spain during the 2018/2019 season using Hoisan software tool. The analysis of the relationships among behaviors has been performed using Polar Coordinates analysis as well as data mining analysis: clustering and decision tree classifier. Results show significant relationships that allow us to tactically interpret the pick and roll situations in men's and women's professional basketball players in Spain, allowing us to develop more intervention programs which will optimize training and improve players performance.The open nature of basketball gives it a large uncertainty that makes hard the tactical analysis of the situations that happen in the game. Specifically, screens are one of the offensive tactical elements most used in basketball and one example of a tactical situation that needs the highest preparation level to get a good performance in the competition. The aim of this study is to differentiate these player behaviors by gender using data mining and polar coordinates analysis. Therefore, one  Cooperative-opposition collective sports, such as basketball, are characterized by a high motor interaction and a high degree of uncertainty in those interactions   and the square of the Zsum of the Y (retrospective):On the other hand, the polar coordinate technique uses a sequential prospective and retrospective lag analysis of the recorded behaviors Sackett, . It alloCochran, . The disY/Radius) will determine the excitatory or inhibitory nature of the relationship  of the ACB league and three women's teams  of basketball of the 2018–2019 season were chosen, and a total of three games of each category in the regular phase were analyzed. Finally, 176 ball screen situations from the ACB League and 117 ball screen situations from the Women's League were observed and coded.According to the Belmont Report and the standards of competence, since the videotapes that we have analyzed for this study are in the public domain, it has not been necessary to obtain informed consent from the participants. The Belmont Report describes basic ethical principles and guidelines concerning ethical issues in human subject research. According to these guidelines, images of public behavior can be used for research without getting the informed consent of the athletes , was created with the HOISAN software  design has been used. The results obtained by the SAGT program showed that both intraobserver and interobserver variability was associated with the category facet at 99.39 and 93.32% respectively, being 0 for the observers facet and 0.60 and 6.67% in the interaction of the categories–observer facets. A two-facet design, observers and categories (O/C), has been also carried out for the homogeneity analysis of the tool. This design ascertains the degree of differentiation among the different actions of the game using the proposed categories. The results showed that variability is 99.39% associated with the category facet, 0.60% for the observers/categories interaction, and 0.00% for the observer facet. Since the generalization coefficients tend to zero, the homogeneity of the categories can be admitted to be optimal in the sense of differentiators . Finally, an absolute Once the tool has been validated and the reliability of the observers has been estimated by means of the data quality and generalizability analyses, the observations of the six matches have been coded and the polar coordinate analyses have been carried out using the HOISAN program , the quadrant assignment, the module, the angle, and the transformed angle for the rest of the categories : Exit on the opposite side of the ball screen (SCBQ) and exit on the side of the ball screen (SLBQ).Subsequently, the gender-differentiated data matrices have been used for data mining analysis Weka 3, . This tyThe polar coordinates analysis shows the results for each gender  in two-ball screens, on the one hand, the focal behavior “output on the opposite side of the ball screen” (SCBQ) and on the other hand, the “output on the side of the ball screen” (SLBQ).Related to the starting focal behavior “on the opposite side of the ball screen” (SCBQ), the results show the following significant relationships in quadrant I: BLE , BLA , and D2-1  for the male category; and Q2-2 (from min 5 to 0 of the second quarter), D2-2 (defender behind the screener), and D2-3 (defender behind the three players) for the female category. In quadrant II, Q1-1 (from min 10 to 5 of the first quarter) and G1-5 (winning by between 1 and 5 points) are shown as significant behaviors for the male category; and for the female category Q2-1 (from min 10 to 5 of the first quarter), TD (disadvantageous shot) and PERD (loss of possession). In quadrant III, the pairing behaviors P6-10 (losing between 6 and 10 points) and P+10 (losing more than 10 points) are significant for both the male and female categories. In the male category, the behaviors Q2-1 (from min 10 to 5 of the second quarter), Q2-2 (from min 5 to 0 of the second quarter), BLB , D2BQ , and D2S (defender chases) are also significant. Finally, quadrant IV shows the conditioned behaviors G6-10 (winning from 6 to 10 points) and EMP (tie) for the male category, and Q1-2 (from min 5 to 0 of the first quarter) for both categories.The results of the polar coordinates analysis for the focal behavior of the SLBQ show several significant relationships for each category. In the first quadrant, for the male category, behaviors Q2-1, Q2-2, BLB, D2BQ, and D2S are significant. In contrast, the female category does not show significant relationships with any of the mating behaviors. In quadrant II, the significant conditioned behaviors are: G6-10, EMP (tie) and D1C (defender changes defender) for the male category; and Q4-1 (from min 10 to 5 of the fourth quarter) for the female category. In the third quadrant are Q1-1, BLA, and D2-1  for the male category, and Q2-2 and G6-10 for the female category. Finally, in quadrant IV, the behaviors G1-5 (winning between 1 and 5 points) and BLE  are significant for the male category; and Q2-1 (from min 10 to 5 of the second quarter), Q3-2 (from min 5 to 0 of the third quarter), A1E (attacker makes a shot), and PERD (loss of possession) for the female category.An analysis technique known as clustering has been used, which allows the identification of typologies or groups where the elements are very similar to each other and very different from those of the other groups. K-means algorithm has been used for this clustering, which is an algorithm classified as a partitioning and repositioning method. This algorithm is so far the most widely used in scientific and industrial applications. The name comes from the fact that it represents each of the clusters by the average (or weighted average) of its points, i.e. by its centroid. The centroid representation has the advantage that it has an immediate graphical and statistical significance. The sum of the discrepancies between a point and its centroid, expressed through the appropriate distance, is used as the objective function. The objective function, sum of the squares of the errors between the points and their respective centroids, is equal to the total variance within the cluster itself. The sum of squares of the errors can be rationalized as the negative of the log-likelihood for mixed models using normal distributions.Each cluster represents a “quotient set.” The results show that most of the players, regardless of gender, usually make simple ball screens, the player with the ball is the point guard, the screener is the center, there is no second ball screen, the ball screen zones are usually zones 2 and 3, the defensive system is individual, and the defender is close to the player with the ball.In women's basketball, normally the attacker having the ball passes it and the second attacker makes a pick and roll or pick and pop. Looking at male players, the attacker having the ball hands it and the second attacker usually makes Pick and Roll. Normally, the situation is completed by continuation of the play in women; whereas men either continue the play or the point guard is the player who creates advantage.The gender decision tree as a function of factor challenge attributes has a hit ratio of 80%, and it is shown in The attributes that produce a significance in the sex of the player stand out; these are: MARC , A1 (ATTACKER 1), A2 (ATTACKER 2), and D1 (DEFENDER 1). Specifically, an interesting result is that only female teams win scoring 10 points more than the other team, but when wining scoring is more than 6 and less than 10 points than the other team, the behavior of attacker 1 is the factor determining the gender. Only female attacker 2 will make a pick and pop compared with a male attacker.The objective of this work is to identify, by means of data mining and polar coordinates analysis, patterns in the recorded data to explain and predict the behaviors occurring in the execution of the tactical means of ball screen in professional basketball teams in Spain, differentiating it according to gender.ad hoc observation tool created has passed the data quality and generalizability analysis tests, which allows a reliable recording of the behaviors appearing during the game action. In addition, it has been shown that polar coordinates analysis is a useful technique for the study of the relationships established between behaviors in a tactical situation in competitive team sports  and the small forward (BLA), who are players with a percentage of success in the three-point shot of 34.96% and 33.68%, respectively , and on the other hand, in male category the marker in favor (G6-10) is inhibited (IV quadrant). A study has shown that the use of pick and roll with the unfavorable marker is bigger , which could be because of the fact that the use of pick and roll is smaller for a favorable score .The findings of both analyses suggest that these techniques are suitable to be applied in sport psychology, specifically to explore different variables that are usually studied in this field of knowledge.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.AH-M, VM-S, RR, JP-B, JM-B, CF, BT-G, and JV-D participated in the study design and data collection, performed statistical analyses and contributed to the interpretation of the results, wrote the manuscript, approved the final manuscript as submitted, and reviewed and provided feedback to the manuscript. All authors made substantial contributions to the final manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.