We show that with the inhibitorsthe free energy cost to reach the charge-separated state of the active-sitedyad is lower, with N3 inducing the most significant reduction. Wealso show that a few key sites (including specific water molecules)significantly enhance or reduce the thermodynamic feasibility of thePT reaction, with selective desolvation of the active site playinga crucial role. The approach presented is a cost-effective procedureto identify the enzyme regions that control the activation of thecatalytic reaction and is thus also useful to guide the design ofinhibitors.The catalytic reactionin SARS-CoV-2 main protease is activatedby a proton transfer (PT) from Cys145 to His41. The same PT is likelyalso required for the covalent binding of some inhibitors. Here weuse a multiscale computational approach to investigate the PT thermodynamicsin the apo enzyme and in complex with two potent inhibitors, N3 andthe α-ketoamide  In addition, the recognition sequenceof SARS-CoV-2 Mpro is different from that of all knownhuman proteases, and thus inhibitors of its activity are less likelyto be toxic.2 Furthermore, the structureof Mpro and its catalytic pocket is very similar amongthe coronavirus family, suggesting that broad-spectrum antiviral drugsmight be obtained by targeting this enzyme.1The rapidand broad spread ofthe pandemic caused by severe acute respiratory syndrome coronavirus2 (SARS-CoV-2) has led to an urgent need for effective therapeutics.One of the most promising targets for drug development among coronavirusesis the main protease . Similar to other cysteine proteases, SARS-CoV-2 Mpro features a cysteine-histidine catalytic dyad (Cys145/His41)(see –/His41+) which reactswith the substrate.1 However, the PT mechanismin the apo enzyme and in the presence of the functional substrateis still under debate.7SARS-CoV-2 Ms41)see 1. Proteipro, suchas Michael acceptors and ketoamides,8 also requirea deprotonated Cys145 to covalently bind the active site. Diversebinding mechanisms between inhibitors and enzymes featuring an active-sitecysteine have been reported, either involving a direct PT reactionbetween the inhibitor and the cysteine9 or requiring a PT reaction from the cysteine to a protein base priorto the binding reaction.10 In the caseof SARS-CoV-2 Mpro previous computational works, whereinMichael acceptors12 and ketoamides13 wereinvestigated, suggested that the physiological PT reaction from Cys145to His41 occurs prior to covalent binding of the inhibitor. Thesecomputational works11 also showed that the PT reactionfree energy in the presence of two potent inhibitors of SARS-CoV-2Mpro, namely the peptidomimetic N3 and the α-ketoamide 13b,8 accounts for 50% and 37%, respectively,of the total activation free energy for the formation of the covalentcomplex and thus the PT relevantly contributes to the rate-determiningstep. Hence, the improvement of the stability of the charged catalyticdyad by the inhibitor binding could be a strategy to promote catalysis.14 In this perspective, the knowledgeof the protein regions that are responsible for the enhancement orreduction of the thermodynamic feasibility of this PT, can guide thedesign of the recognition motifs of an inhibitor to the catalyticsite of the enzyme with the aim of promoting the PT reaction, andthus the subsequent formation of a covalent bond.Some classes of inhibitors of SARS-CoV-2 Mpro, both in the apo enzyme and in complexwith the inhibitors N3 and 13b. These two inhibitorsare peptidomimetic compounds shown in 813b is a capped dipeptide with an α-ketoamidewarhead, a γ-lactam moiety designed as a glutamine surrogateat position P1, a benzyl group at position P1′, a cyclopropylmethyl moiety at position P2, a pyridone in the P3–P2 position,and a hydrophobic Boc group at position P3.2The presentwork focuses on the investigation of the thermodynamicsof the protonation states of the catalytic dyad and of the PT reactionin SARS-CoV-2 M15 TheMD-PMM approach has been successfully used to investigate the thermodynamicsof electron transfer and PT reactions23 and to identify the protein/enzyme sites that are able to modulatethe charge-transfer energetics,23 also providing hintsfor new possible mutations. With the same approach, we focus hereon the identification of the enzyme regions that can be targeted toinhibit its catalytic activity with particular attention to the roleplayed by the solvent.To investigate the thermodynamics of the PT reaction, we useahybrid quantum/classical approach for the investigation of chemicalprocesses in complex systems based on the joint use of classical moleculardynamics (MD) simulations, quantum mechanical (QM) calculations, andthe perturbed matrix method (PMM).27 also for the investigation of enzyme catalysis,31 the portion of the system in which the chemical event takes placeis treated quantum mechanically  while therest of the system is treated classically and atomistically and exertsan electrostatic perturbation on the QC electronic states. However,the main difference with other hybrid methods is that in the MD-PMMthe whole system configurational space (including the QC) is sampledby fully classical MD simulations and the electrostatic perturbationof the environment on the electronic properties of the QC is included a posteriori. To include the perturbation of the environmenton the QC quantum states, the electrostatic potential and electricfield that each atom of the environment exerts on the QC are evaluatedat each frame of the MD simulation, and their effects on the QC quantumproperties  are calculated.As commonly done in hybrid multiscaleapproaches,SI.Therefore, the instantaneousquantum properties of the QC in thepresence of the environment  are obtainedby expanding the perturbation operator instead of using full electronicstructure calculations. This approximation allows us to estimate theperturbed quantum properties for all the configurations obtained fromclassical MD simulations of the whole system (including the quantumpart) and to employ extensive sampling for the calculation of thereaction thermodynamics. This extensive sampling also allows us toinvestigate the coupling of the quantum observables with the classicaldegrees of freedom of the environment, giving insights into the moleculardeterminants affecting the free-energy change. When charge-transferreactions are investigated, the donor and acceptor can be treatedeither as two separate QCs  or as a single QC. In the present case, the donor and acceptorare treated as a single QC when close together and hydrogen bonded(see below). It has to be pointed out that the accuracy of the overallapproach relies on the accuracy of both the QM calculations and theforce field employed for the classical MD simulations. More detailson the MD-PMM approach can be found in the pro, we selectthe side chains of Cys145 and His41 as QCs.For the configurations in which a direct hydrogen bond (HB) betweenthe catalytic dyad residues is present ,Cys145 and His41 are treated as a unique QC, while when the HB isnot present they are treated as separate QCs (see the SI for details on the definition of the QCs).QM calculations are performed on the above-defined QCs in both thereactant and product ensembles as defined by the following PT reaction:To investigatethe active site PT reaction in SARS-CoV-2 MSI). Two of these simulationsfeatured both Cys145 and His41 in their neutral state : one with His41 protonated at Nε (His41E) and one with His41 protonated at Nδ (His41D).In its neutral state, His41 can be protonated either at its εor at its δ nitrogen, possibly leading to a different structuraland dynamical behavior of the catalytic site and its neighborhood.The third MD simulation was carried out with Cys145 and His41 formingan ionic couple . Information on the catalytic dyad configurationsand interactions is provided in the SI,and a more extensive structural analysis of the MD simulations canbe found in our previous work.32 Then,by applying the MD-PMM approach, we computed at each MD frame foreach simulation ensemble the time evolution of the energy change uponPT that provides the reaction free energy ΔG0 (see eq 6 in the SI).Three MD simulations were performed . This small free energydifference upon tautomerization suggests that in the apo state atphysiological temperatures both protonation states may be accessible.This agrees well with a previous computational work in which the roleof His41 and its protonation state was addressed.13b inhibitors inside the substrate bindingpocket, we simulate the complex between the non-covalently bound inhibitorsand the enzyme. A recent computational work addressing the role ofhistidine protonation in influencing the structural stability of SARS-CoV-2Mpro32 showed that in the presenceof the inhibitor N3 the most stable state is the one with His41D,while in the presence of 13b the most stable state isthe His41E one. Therefore, the computation of the PT energy in thepresence of N3 and 13b focuses on the His41D and His41Ereactant states, respectively. As for the apo-enzyme, for each inhibitortwo MD simulations are performed for the non-covalent complex, i.e.,one in the reactant ensemble and one in the product ensemble.In order to compute the energy variation upon PTin the presenceof the N3 and G0 = 34 ± 6 kJ/mol to ΔG0 =20 ± 6 kJ/mol .6The calculation of the free energy change upon PT in the presenceof  13b see 2. The co37 (see The Perturbed MatrixMethod section in the SI). We thereforeanalyzed the contribution of each protein residue to the electrostaticpotential in order to understand which protein regions contributethe most to the PT energy. This analysis reveals which are the enzymesites that control, via a conformational electrostatic effect, thecatalytic activity that is triggered by the PT reaction in the bindingsite.To gain insightsinto the molecular mechanisms that tune the energeticsof the catalytic site in the reactant state, we analyzed the electrostaticpotential contribution to the PT energy in the apo and inhibitor-boundstates. In fact, the most important contribution to the PT energyfluctuations around the unperturbed ground state energy differencealong the MD simulations is given by the electrostatic potential feltby the QCs13b are relegated to the SI, as the case of N3 is more informative on the protein andsolvent contributions to the PT energy change upon binding. This isbecause the lowering of the free energy cost in forming the ioniccouple is larger upon binding to N3 (from 34 kJ/mol in the apo stateto 20 kJ/mol in the bound state) than to 13b (from 37kJ/mol in the apo state to 31 kJ/mol in the bound state).In what follows we report the results obtained for theapo statewith His41D and the changes induced by the presence of N3, while theresults for the apo state with His41E and the changes occurring uponbinding of qV, i.e., the contribution to the PT energydue to the electrostatic potential computed in the QCs center of mass,of each residue in the MD simulation of the apo state with His41D.In the figure the residues with a negative contribution exert an electrostaticeffect that favors the PT reaction, while the opposite is true forthe residues with a positive contribution. The residues that mostrelevantly contribute to the PT energy are Arg40, Glu166, and Arg188(positive contributions disfavoring PT) and Asp187 (negative contributionfavoring PT). These are charged residues in the vicinity of the catalyticdyad that, besides being energetically relevant, are also structurallyrelevant (see SI for the details). Thecontribution of Ser1 of the other monomer, related to the one of Glu166(see SI for the details), can also be seen.In 39 a possible inhibition strategy could be to target one of the identifiedregions in order to promote an allosteric modulation of the PT energetics.Three additional minor contributions can also be observedin pro (PDB 6wqf)a highly buried water molecule is present, which is packed in a tightHB network involving His41 Nδ, His41 backbone NHgroup, the side chain oxygens of Asp187 and His164 Nδ . Another well-conserved water molecule, Wdyad,can be found in several crystal structures , located withinthe catalytic dyad, almost bridging the sulfur atom of Cys145 andthe Nε atom of His41  along the apo-state simulation reveals that, besidesthe two aforementioned conserved water molecules, there is a highoccupancy of small water wires of 3–4 molecules starting fromWdyad see 4. TherefqV) between the single residue contribution obtained from the MD inthe presence of N3 and that obtained in the apo (Δ(qV) = qV(N3) – qV(apo)) isalso reported. This difference highlights the protein regions thatmore relevantly contribute to the variation of the energy change uponPT in the presence of N3: the residues with a high negative contributionin The analysis of the residues and water moleculesthat contributethe most to the PT energy was also performed for the MD simulationin the reactant ensemble in the presence of N3, along with the directcontribution of N3. The results, reported in pro bound to N3 highlights that the inhibitor backbone forms an antiparallelsheet with residues 164–168 on one side and residues 189–191on the other side. These interactions are essentially preserved inthe MD simulations of the non-covalent complex . The local interactions of N3 with proteinsites different from the catalytic site thus favor the PT reaction.The presence of N3 reduces the electrostatic effect of Arg188 andGlu166 that disfavors the PT in the apo state, both by screening thecatalytic dyad from their charge and by sterically pushing away theirside chains (see The most relevant (positive andnegative) contributions are exertedby Glu166, Arg188, N3, and the solvent. Concerning Glu166 and Arg188,the analysis of the crystal structure of SARS-CoV-2 M see SI, S6. The lConcerning the direct effect of thepresence of N3, it can be seenthat the electrostatic contribution of N3 in Figure S9). Preservation of this HB pattern was already observed in a previoussimulation of a non-covalent complex formed between the enzyme anda model peptide mimicking the polyprotein sequence recognized at theactive site.41 In contrast, significantdifferences are observed in the contributions of Wdyad and its waterwires, that are less positive  than inthe apo state . Thisresult is in agreement with what was observed in previous simulations,wherein the apo state and a non-covalent complex between the enzymeand a model peptide mimicking the polyprotein sequence recognizedat the active site were investigated and compared.41The contribution of Wcat in the N3-boundstate is essentially thesame as that in the apo state see S9. Prese42 Thus, the thermodynamic feasibility of the PT reaction is not theonly factor influencing the reactivity of covalent inhibitors. Nonetheless,the approach presented in this work is envisioned to be of significantaid in the design of new inhibitors by means of computer simulations.In particular, our approach can help identify compounds that can promotethe catalytic PT reaction and, therefore, be good candidates as covalentinhibitors, complementing the information that can be obtained fromthe available computational approaches for drug design.47 Knowledge of the key residues and water molecules that tune thecatalytic PT reaction can in fact guide the analysis of the interactionsbetween the recognition moieties of a candidate compound and the differentsub-sites of the binding pocket of the protein, which is a crucialstep in the design and screening of potential inhibitors. In addition,identification of specific conserved water molecules able to affectthe PT energetics could be used in docking procedures to select whichwater molecules should be explicitly considered. More generally, thepresent approach can be used to reveal key sites in enzymes that canbe mutated in order to affect the catalytic reaction. In addition,the same sites can be targeted with ligands, also in the frameworkof allosteric inhibition, to suppress the enzymatic activity.Covalent inhibition in enzymes is a rather complexprocess, involvingboth thermodynamics and kinetics and influenced by multiple elements,such as solvent effects and conformational fluctuations.SI. In what follows, we outlinethe calculations performed to obtain the PT free energy.1.In the MD-PMM approach,the first stepconsists in defining the portion of the system responsible for thechemical event  to betreated at the quantum-mechanical level. In the present case, theside chains of Cys145 and His41 were selected either as a single oras two separate QCs (see above).2.MD simulations of the whole quantum-center/external-environmentsystem were performed to sample the configurational space of the system.3.Quantum-mechanical calculationswereperformed on the isolated QC(s) at the DFT level to obtain the unperturbedHamiltonian of the QC(s).4.For each MD configuration of the wholesystem, the perturbing effect of the external environment was evaluated:the electrostatic potential and electric field exerted on the QC centerof mass by each atom belonging to the environment was calculated.5.For each MD configuration,the perturbedHamiltonian  was constructed and diagonalized toprovide a set of eigenvalues and eigenvectors.6.From the eigenvalues and eigenvectorsof the perturbed Hamiltonian, the QC properties/observables of interestin the presence of the perturbing environment can be calculated asa function of time. In the present case, the energy change upon PTwas evaluated for each MD configuration. From this energy time seriesthe free energy change upon PT was calculated.The theoretical background of the MD-PMM approach is describedin the


Analyses presented in the article were carried out in order to characterize the main parameters of the shaped charge jet formed due to detonation of the PG-7VM warhead. As opposed to the previously published studies in which rolled homogeneous armored steel was mainly used as a target, in the current work the warhead penetration capability was determined against more contemporary high-hardness (500 HB) ARMSTAL 30PM steel armor with precisely determined mechanical properties. The research included experimental depth of penetration tests and their numerical reproduction in the LS-Dyna software. Special attention was paid to factors that could perturbate the shaped charge jet formation process and under- or overestimate its penetration capability. For this reason, warheads were X-ray inspected for structural discrepancies  and properties of materials  were analyzed before the experiments. The numerical model of the warhead was defined more accurately than in previously published studies, since it was based on the real grenade dimensions and its technical documentation. Thanks to this, the depth of penetration of the target made of ARMSTAL 30PM armored steel plates by the shaped charge jet formed from the PG-7VM warhead obtained by numerical simulation was consistent with the experimental results and equaled 278 mm and 280 mm, respectively. The difference between the experimental and numerical value was smaller than 1%, which confirms that the developed methodology of modeling allows users to properly reproduce the PG-7VM shaped charge jet formation and target penetration processes. A verified numerical model of the shaped charge jet penetration into a steel target was used to determine depth of penetration in function of stand-off distance for the PG-7VM warhead. A maximum depth of penetration of about 317 mm was obtained for the stand-off distance of 360 mm, which may indicate the potential direction of modernization of warheads. High-explosive anti-tank (HEAT) warheads ,2,3,4, bRecently developed and technologically advanced military HEAT warheads have sophisticated designs, allowing them to obtain a great penetration capability of armor. Depending on the type  the most powerful HEAT warheads may penetrate up to 1500 mm of rolled homogeneous armor (RHA) . However® software was used to investigate the influence of SC asymmetries on the SCJ characteristics in the work [Effectiveness of HEAT warheads is determined mainly during experimental depth of penetration (DoP) tests. However, currently used measurement techniques, which are based mainly on flash radiography and X-ray pictures of the SCJ at predetermined times, are unable to provide all the necessary data about the entire phenomenon. Although, X-ray pictures may be subsequently used as input data for the analytical models, allowing calculation of the basic SCJ parameters, such a combined experimental–analytical approach is effective only in analysis of the simplest penetration scenarios. For this reason, numerical simulations are often used as a support to experimental analyses. Numerical methods allow researchers to collect more information about the entire process of SCJ formation and penetration, e.g., pressure, density, or velocity distribution at different times. Nowadays, a few different modeling approaches are used in analysis of SCJs. In the work , a Lagrathe work . Two-dimthe work  to simulAlthough, multiple studies on the effectiveness of various HEAT warheads with different numbers of SCs ,22, lineAn additional issue is the relevance of RHA as a reference material simulating passive armors of modern heavy-armored vehicles. RHA has been used as a reference target for over 50 years and its main advantage is that effectiveness of various warheads can be easily compared on the basis of the values of DoP in RHA. However, during those 50 years, technology of production of armored steels has significantly improved and RHA steel was almost completely replaced with new, more durable, and harder steel grades. Strength and hardness of currently offered armored steel is almost twice that of RHA  . Taking In view of the foregoing considerations, the main aim of the work presented in the article was evaluation of the actual PG-7VM warhead performance against the target made of high-hardness (500 HB) ARMSTAL 30PM armored steel  with preEffective and reliable methodology of numerical modeling of shaped charge jet penetration into high-hardness armored steel targets could be used in the future in all kind of optimization studies of both warheads and armor designs.Experimental DoP tests were carried out to determine the warhead penetration capability and to collect data required for further validation of the numerical model of the phenomenon. The experiments were performed at the Military Institute of Armament Technology (MIAT) proving ground in Poland. During the tests, the PG-7VM warheads were placed at an angle of α = 60° in relation to the vector normal to the surface of the target  in orderIn order to increase the reliability of the results before the experiments, the PG-7VM warheads selected for the tests were X-ray inspected for their structural and geometrical discrepancies  to exclude some factors that could perturbate the jet formation and penetration process. The X-ray real-time radioscopy (RTR) diagnostic system (XDS) MU17F 225-9  was used c,d.The X-ray inspection is particularly important because the effectiveness of the PG-7VM warhead is highly dependent on the axial alignment precision of their elements during the manufacturing and assembling process. The most effective (in terms of penetration capability of armor) are warheads in which the dimensional deviations from axial symmetry of liner and explosive do not exceed 0.03 mm. The penetration capability of the warhead significantly decreases with the increase of inaccuracy of production or assembling. Depending on the deformation rate of the liner and the high explosive charge, the process of SCJ formation will be disturbed or will not occur at all. Effects of the warhead’s influence on the target are then comparable to the simple detonation of explosive charge contained in the warhead body. Only the warheads with no discrepancies  required for subsequent definition and validation of the numerical model of the material. The following tests were carried out:Hardness measurements were carried out with the use of a Brinell machine, both parallel and perpendicular to the rolling direction (EN ISO 6506-1). Before the measurements, the surfaces of the plate were polished. Impact strength of ARMSTAL 30PM was tested according to well-known Charpy method (EN 10 045-1). Tests were carried out for the samples with U- and V- shape notches at temperatures of +20 °C and −40 °C, respectively. The geometry of the samples is presented in Mechanical properties of the ARMSTAL 30PM were analyzed on a Zwick Z100 universal testing machine  with servo-hydraulic control. Specimens for the tests were prepared from 4, 6, 8, and 10 mm thick plates using a wire electrical discharge machine. Geometry of the samples prepared for the tests were shown in Triaxial, close to hydrostatic compression in the sample/holder interface zones;Triaxial non-homogeneous compression in the middle layers of the sample;Mixed compressive tensile state in the middle subsurface layers of the sample with a tensile stress in the circumferential direction.Force was applied to the specimen holders with end grippers and their displacements were recorded. Engineering stresses and strains values were calculated on the basis of the force–displacement curves. After necking or barreling of the sample during tension and compression tests, respectively, diversified, three-dimensional stress states in the samples were generated. The barreling effect during compression tests is caused by friction between the sample and the surface of the specimen holders. Various stress states can be distinguished in individual areas of the sample:true—true stress, εtrue—true strain, P—force, Ai—area of actual cross-section of the sample, A0–area of initial cross-section of the sample.Due to barreling and necking effects, determination of the true stresses and strains in the sample requires continuous measurement of the actual cross-section of the sample, e.g., by means of digital image correlation equipment. In the study, the compression and tension processes were recorded with a camera and the values of actual cross-sections of the samples were calculated from the recordings on the basis of the extremal lateral dimension of the tested samples, located usually in the middle of their height, where the maximum deformation occurs. Assuming negligible changes in the volume of the samples, the true stresses and strains were calculated from the following equations:The results of quasi-static compression tests of the ARMSTAL 30PM steel are shown in Mechanical properties of ARMSTAL 30PM obtained during the tests on the samples taken parallel and perpendicular to the rolling direction were similar to what is known about the high uniformity and low anisotropy of the material. The differences in the results obtained for the samples prepared from the plates with different thickness were also very small. The yield strength and ultimate tensile strength of the material exceeded the minimal values that were provided in the manufacturer datasheet . On the PG-7V and PG-7VM warheads are filled with an A-IX-1 explosive composition (phlegmatized RDX), which consists of 94–96% RDX (hexogen) and 4–6% wax. More modern warheads are filled with OKFOL explosive composition, which consist of 96% HMX and 4% wax . ExplosiDifferential scanning calorimetry (DSC) analysis performed with the use of DSC Q100 apparatus of TA Instruments ;Thermogravimetry (TGA) analysis, performed with the use of the TG Q50 apparatus of TA Instruments ;Pycnometric density analysis, performed with the use of the Ultrapyc 1200e by Quanta Chrome Instruments ;Moisture analysis, performed with the use of glass weighing vessels and chamber thermostats with a water jacket;Stability analysis carried out with the use of glass weighing vessels and chamber thermostats with a water jacket.Phlegmatized hexogen was subjected to the following tests:onset—temperature at transformation start; Tmax—temperature at maximum peak, in which the process takes place at the highest rate; Tend—temperature at end of transformation; Δm—mass loss of the tested sample in percents; Q—heat of transformation (J/g). The tests were performed in non-hermetic aluminum vessels (with a lid), in a nitrogen atmosphere, with a heating rate of 10 °C/min.The results of DSC and TGA analyses for the tested samples of phlegmatized hexogen (A-IX-1) are shown in onset temperature of the thermal decomposition process determined with extrapolation were 217.1–219.5 °C and 217.2–221.0 °C for DSC and TGA analyses respectively. The largest differences were observed in the values of the thermal decomposition of hexogen contained in the tested composition (1986–2507 J/g). The decomposition process is a highly exothermic transformation, during which, in the case of non-hermetic vessels, a partial loss of gaseous products may occur (through the upper part of the measuring vessel). The mass loss of the tested explosive samples was in the range from 95.9% to 99.0%. The differences in the recorded mass may result from the amount of wax in a given production batch of A-IX-1 composition. On the basis of the authors experience, it may be assumed that the content of stearin or ceresin in the composition A-IX-1 may vary within ±2%, which was confirmed by the results of TGA analyses.On the basis of the obtained results, it can be concluded that the temperature of the beginning of the melting process of the A-IX-1 explosive composition is within the range of 204.0 to 204.3 °C. The TThe results of the density determination with the pycnometric method, as well as humidity and stability by the weight method, are presented in 3. Actual density of the charge after the pressing process, which is indicated in the PG-7VM warhead technical documentation, is 1.63 g/cm3. Since the results of performed physicochemical tests were similar (even though samples of explosive compositions were extracted from warheads from different production batches and year of manufacture), it can be assumed that that the explosive compositions extracted from the PG-7VM warheads have not undergone excessive aging due to the long storage and should have properties similar to those reported in the manufacturer datasheet. Therefore, the density of the charge was assumed as 1.63 g/cm3, which gives the detonation velocity of about 8200 m/s according to the relationship between the detonation velocity and density of the phlegmatized RDX, available in the literature and presented in The measured density of the A-IX-1 composition extracted from PG-7VM warhead ranged from 1.70 to 1.73 g/cm3. The batch-to-batch differences may be caused by the wax content. The higher the wax content, the lower the density value. The results of the humidity and stability tests for all tested samples were below 0.05% and 0.1%, respectively. However, it should be noted that the density of the charge is always lower than the density of the extracted composition powder due to the limitations of the pressing process. Theoretical density of composition containing 96% of RDX and 4% of wax may reach up to 1.78 g/cmNumerical simulations may constitute an effective tool supporting experimental studies of high-speed phenomena that are inconvenient to analyze with the use of traditional measuring techniques. However, the reliability of the results of simulations is strongly dependent on the accuracy of the model. In the literature, there is a lack of reliable numerical studies related to PG-7VM efficiency. In those that are available, the geometry of the warhead is often modeled in an inappropriate or too simplified way and the results are usually limited to the value of DoP in RHA steel. One of the main objectives of this study was to develop an effective and accurate methodology of modeling shaped charge jet penetration into high-hardness armored steel targets. Numerical simulations were carried out in order to better understand the mechanisms of the phenomenon and to collect data related to SCJ parameters during the SCJ formation and target penetration process.Numerical simulations of the PG-7VM SCJ formation and target penetration processes were carried out in the LS-Dyna software . A threeDiscretization of the simulation components is shown in On the external segments of the model, the boundary condition was applied to prevent artificial stress wave reflections generated at the model boundaries from reentering the model and contaminating the results. In the discretization of the target in order to limit the number of elements, the mesh of the individual armor plates was refined in the SCJ impact point zone. The distance between the neighboring nodes ranged from approximately Δx = Δy = Δz = 0.5 mm in the SCJ impact zone to Δx = Δy = Δz = 2 mm in non-deformed armor areas. The elements of the mesh of other components of the warhead had the size of Δx = Δy = Δz = 0.5 mm.The model of the whole phenomenon is shown in Several contact models, based mainly on the penalty function method  and consMetals—steel , copper , and aluminum alloys ;Plastics—wave shaper, separators, etc.;Explosive;Air filling computational domain.Four general types of materials were modeled in the work:Since commonly used and well-known constitutive relations available in Ls-Dyna software  were useThe popular material model developed by Johnson and Cook (J-C) ,50,51,52n) was defined according to the results of material characterization tests described in chapter 2.2.2. Strain rate hardening (parameter C), thermal sensitivity (parameter m), and the manner of failure of the material  were assumed to be similar to the other high-strength steels of 500 HB class and were adopted on the basis of the works [Values presented in he works ,55,56,57The A-IX-1 explosive composition filling the PG-7VM warhead was described with high-explosive burn (HEB) material model and Jones–Wilkins–Lee (JWL) equations of state (EOS) , which aThe computational domain filled with air was described with a null material model combined with linear polynomial EOS . The matThe results of the DoP experimental tests are shown in Determined average penetration capability of the PG-7VM warhead (DP = 280 mm) constituted the reference value in subsequent numerical reproduction of the SCJ formation and penetration analyses.The results of the simulation of SCJ formation due to the detonation of explosives in the PG-7VM warhead are presented in this chapter. The propagation of the shock front as well as expansion of the detonation products are shown in The influence of the wave shaper on the detonation wave propagation can be clearly seen in the 4–107/s. The liner strains may exceed 1000% under very large hydrodynamic pressures (average pressure of approximately 15–55 GPa). The collapse of the liner material on the axis of the warhead forced a portion of the liner to form a high-velocity (2–8 km/s) jet. Since there was a large velocity gradient between the front (tip) and the rear part (slug) of the jet, it was stretched until it lost its integrity. At the same time, the expansion of the detonation products in the radial direction was evolving  and outer (on the explosive side) surface of the liner  to the base of the cone (about 2 km/s and 0 km/s for the tracer nodes located on the inner and outer surfaces of the liner respectively) a.The radial velocities of the tracer nodes located on the inner and outer surface of the liner were plotted against time in 6–107/s. Therefore, the importance of target strength was significantly reduced in comparison to the impacts at lower velocities (v ≤ 1000 m/s). According to the information available in the literature, the SCJ penetration in armor plate is 10–15% [The results of simulation of SCJ penetration into a steel target are presented in this chapter. The deformations of the components of the simulation at different times after the detonation of the PG-7M warhead are shown in s 10–15%  or even s 10–15%  less thaSince two symmetry planes were used in the simulations and the warhead did not have any discrepancies, the SCJ traveled in a straight line. All the off-axis velocities of the jet particles were caused by the target reaction forces as well as the pressure of subsequent liner elements .The cavity produced in the target was due to the lateral displacement of armor and jet elements by the high pressures that were generated. The penetration depth, hole dimensions and penetration velocities were measured in the simulations .Since in the simulations, two symmetry planes were used, the SCJ impact direction was perpendicular to the surface of the target and the holes in the first three plates did not have the asymmetrical shape like in experiments. The maximal dimensions of the inlet holes in the simulations were 16 × 16 mm. The holes in the other plates were circular with the diameter of approximately 10 mm. The depth of penetration in the simulation was DP = 278 mm. The difference between the experimental and numerical values was 2 mm (≤ 1%). The rear portion of the jet with the velocity lower than 2 km/s did not significantly contribute to the penetration. The final DoP = 278 mm was obtained at time t = 420 µs.Axial velocity and pressure distribution in the SCJ and the target at selected moments of time are presented in A verified numerical model of the phenomenon of PG7-VM SCJ penetration into an ARMSTAL 30PM steel target was used to determine the basic characteristic of the PG-7VM warhead efficiency—DoP as a function of SoD. The relationship is shown in One of the consequences of using axisymmetric formulation is that some phenomena, e.g., lateral SCJ dispersion, could not be properly reproduced and the subsequent SCJ elements hit at the same point of the target as the previous elements. As a result, the plot of DoP as a function of SoD was similar to that of the perfect SC. Only the SCJ breakup mechanisms negatively affected the DoP of the target obtained at large SoD. However, the general tendency was determined and the maximum DoP = 317 mm was obtained for the SoD = 360 mm.f = 0.65, while in the work [f = 0.78.On the basis of the simulation results, it can be concluded that since the penetration crater in the ARMSTAL 30PM target was very deep (about 280 mm) and the SCJ interacted with a great number of target elements, the whole numerical model of the phenomenon may be very sensitive to the values of adopted target material failure criteria, as well as the methods of target discretization (mesh density). In the analyses, the value of effective plastic strain at failure (PSFAIL) was adopted as a target failure criterion. When the effective plastic strain in the element exceeded the defined limiting value of the PSFAIL parameter, the element was removed from the model. A set of additional simulations were carried out in which four different values of PSFAIL in the target material model were adopted . The average value of failure strain was determined during the experimental compression tests and equaled εthe work  the authThe comparison of the simulation results in which different values of effective plastic strain at failure were adopted in the target material model are shown in f = 0.65) or available in the literature (εf = 0.78) [On the basis of the performed calculations, it can be concluded that the model shows a relatively low sensitivity to changes of the PSFAIL value in the range of 0.1–0.6. Increasing the PSFAIL for the target material (ARMSTAL 30PM) by 33% from the value of PSFAIL = 0.6 to PSFAIL = 0.8 reduces the crater depth in steel plates by about 7% (from 280 mm to 260 mm). For higher PSFAIL values, the differences are even lower. The model shows higher sensitiveness when the PSFAIL value is reduced from 0.6 to 0.4. The target elements then erode much faster during the jet penetration process, which results in a complete penetration of the target with a thickness of 300 mm. The target penetration depth equal to DoP = 2 80 mm, i.e., the same as in the experimental tests, was obtained for the value of PSFAIL = 0.63. This value is slightly lower than that determined during the experimental compression tests of ARMSTAL 30PM steel samples (ε = 0.78) .Based on the results of analyses in which different sizes of finite element meshes were used in the target b, it shoTaking into account the slight differences in the obtained calculation results  and a large growth of required computational cost (time required to finish the computation increased from 17 to 38 h), use of elements with the size of Δx = Δy = Δz = 0.25 mm in analysis of this specific phenomenon seems to be unjustified from an economic point of view.In the literature, there is a lack of accurate and reliable research related to the performance of the most common PG-7VM warhead against modern high-hardness armored steels.In the present paper, the penetration capability of the PG-7VM warhead was determined against high-hardness (≥500 HB) ARMSTAL 30PM armored steel. The average depth of penetration of about 280 mm was obtained during the tests.In the present study, much attention was paid to exclude all the factors that could negatively affect (under- or overestimate) results of warhead penetration capability tests. Before the experiments, the presence of structural discrepancies in the warheads were X-ray inspected and material properties of explosive, target, and most important warhead components were analyzed during material characterization tests. The reliability of the results was significantly increased in this way.The numerical model of the warhead was defined more accurately than in previously published studies, since it was based on the real grenade dimensions and its technical documentation. Thanks to this, the difference between the experimental and numerical values of DoP was smaller than 1%, which confirms that developed methodology of modeling allows researchers to properly reproduce the PG-7VM shaped charge jet formation and target penetration processes.Performing numerical simulations facilitates a more precise analysis of the phenomenon and SCJ parameters. A verified numerical model of the PG-7VM SCJ penetration into ARMSTAL 30PM armored steel target was used to determine DoP in function of SoD. Maximum DoP = 317 mm was obtained for the SoD = 360 mm.A combined approach based on experimental tests and developed methodology of modeling of SCJ penetration into high-hardness armored steel targets could be used in the future in all kinds of optimization studies of different HEAT warheads and armor designs.On the basis of literature review as well as performed experimental and numerical analyses the following conclusions can be drawn:


Background: Thrombophilic mutations in genes for factor V Leiden and factor II prothrombin are among the most important risk factors for developing the thromboembolic disease (TED), along with the use of oral contraceptives (OCs) or smoking. Aim: This study aimed to investigate the occurrence of risk factors in young women using droplet digital PCR (ddPCR) and, based on the results of this investigation, to perform a cost–benefit analysis of ddPCR-based screening in young women starting to take OCs compared to the treatment costs of patients who develop preventable TED in the Czech Republic. Methods: In this cross-sectional study, female university students filled in a questionnaire and provided a blood sample for DNA isolation and ddPCR analysis of both aforementioned genetic risk factors. The results, along with data from literature and web search, were used for cost–benefit analysis valid for the Czech Republic. Results: Out of 148 participants, 30 (20%) were smokers and 49 (33%) took OCs. A mutation was confirmed in 6 women (4.1%) in the factor V gene and in 3 women (2%) in the factor II gene, respectively. A model calculation on a cohort of 50,000 women starting to use contraceptives in the Czech Republic every year showed that at maximum compliance, , screening could prevent 68 cases of TED over the course of the mean period of OC use (5.7 years). Economically, the costs of testing in this cohort (2.25 mil. USD) would be significantly lower than prevented treatment costs (16 mil. USD at maximum compliance); the cost–benefit break-even point would be at 14.1% compliance. Conclusion: The cost–benefit analysis based on our results indicates that screening for factor V Leiden and factor II prothrombin in young women before starting to use OCs would, in the conditions of the Czech Republic, likely be highly economically effective. The presented study is a small part of the HAIE research, which, in addition to comparing the health impacts in an environmentally polluted industrial and non-industrial region, assesses health risks and their perceptions for different lifestyles of all ages. This article emphasizes the role of prevention and the responsible approach of young women to the health risks of arterial embolism and thrombosis  associated with the use of oral contraceptives and smoking ,6,7,8, aOCs are used by over 100 million women worldwide. Nowadays, contraceptives with a low estrogen content are available; the increased risk of DVT associated with OC use, nevertheless, persists. The risk is highest in the first year of OCs use and, if other risk factors, such as congenital thrombophilia or smoking, are present, it increases further ,13,14.Individuals with mutations in FV and FII genes have no symptoms, and the presence of the mutation is usually revealed only as a result of a DVT or PE event. At present, routine screening of women before their first OCs prescription is not recommended, and the genetic analysis is performed only in individuals with events of: recurrent DVT, first unprovoked DVT, DVT in unusual locations, DVT associated with OC use, DVT during pregnancy or puerperium, recurrent abortions in the 1st trimester or stillbirth and DVT present in a family member at the age of 50 or younger.These recommendations lead to performing genetic analysis only in a limited group of individuals  and is practically in opposition to the conclusions of studies warning from the use of OCs in women with congenital thrombophilic mutations ,15. We hNowadays, nevertheless, the gradual progress in laboratory DNA analyses has brought methods that are suitable for screening purposes, such as relatively cheap  PCR techniques that could lead to a reduction of the screening costs. Hence, we have performed the presented pilot study in young women, aiming (i) to find out the prevalence of risk factors  in young Czech women; (ii) to evaluate the suitability and costs of mutation screening using the novel droplet digital PCR (ddPCR) method, which appears to be a cheaper, while highly sensitive (0.001%), approach allowing absolute quantification ; based oThis cross-sectional epidemiological study was performed at the Faculty of Medicine, University of Ostrava. Participation in the study was offered to female students of the University of Ostrava, of whom 148 volunteered. The principal motivation for participants was the acquisition of the information about their own health risks associated with thrombophilia and they were informed about the results of their individual examinations.The study, as well as the informed consent that was signed by all participants, was approved by the Ethics Committee of the Faculty of Medicine, University of Ostrava. The participants also filled in a questionnaire containing questions regarding their personal and family history, as well as the presence of risk factors of TED . Subsequently, 2.5 mL of full blood were taken from each participant into Vacutainer tubes with EDTA, left for at least 2 h at room temperature and subsequently frozen to −24°C until the time of DNA isolation. This was performed manually using the NucleoSpin blood kit  and the DNA concentration and purity were verified using a microvolume spectrophotometer . The DNA concentration was decisive for the amount of the DNA template used for subsequent ddPCR analysis. The reaction mixture contained the template, PCR water, ddPCR supermix , and ddPCR mutation detection assay for the FV and FII mutations , respectively.Commercial prices of the analyses of individual thrombophilic mutations were acquired from the laboratory pricelists ,19,20,21The calculations of the numbers of cases in the individual subgroups were performed according to the formula:i = number of events in the individual subgroup per yearNP = the considered study population I = incidence per 10,000 general population f = fraction of the total population with the particular risk factori = risk factor of TED occurring  in the respective subgroupRF10,000 = adjustment to the incidenceThe total number of prevented events at 100% compliance was then calculated asT is the mean period of OC use in the Czech Republicnon-preventable is the number of non-preventable cases (describing the risk in mutation carriers that cannot be affected by responsible behavior).and NBasic descriptive statistics  were used for the characterization of the study group. The occurrence of the factors was expressed as the frequency with a binomial confidence interval (CI). All analyses were performed in Stata version 14 .148 women aged 18 to 37 were included in the study, of which 30 (20%) were smokers and 49 (33%) took OCs. DVT and embolism were present in the family history of 10 and 3 women, respectively. One participant had a personal history of thrombosis. Two women in the patient group had a personal history of abortion and one of premature birth (6th month).DNA concentrations in the purified samples ranged from 3.47 to 88.232 ng/µL, purity from 1.370 to 2.250. ddPCR detected factor V Leiden mutation in 6 women , and mutation in the FII prothrombin gene in three women . Two out of these women with a positive finding of thrombophilic mutation used OCs (22.2%) and two were smokers (22.2%). Hence, at least one of the studied mutations was present in 6.1% of women in our study group (95% CI: 2.8–11.2%); 44.4% of these had an additional risk factor  further increasing the risk of TED. One of them had a family history of embolism, one of myocardial infarction, and one had thrombosis in her personal history. The overview of the participants of the study, participants with thrombophilic mutation, and other risk factors, is detailed in All women in whom the mutation was detected were asked after 6 months if their lifestyle has changed from the perspective of the additional risk factors . Both women with the mutation who were using OCs before the analysis discontinued OCs and both women who smoked ceased smoking after receiving the information; the compliance in our sample was, therefore, 100%.The combined commercial price of the analysis of FV and FII mutations in the Czech Republic for self-payers utilizing current methods ranges from 56 to 140 USD ,19,20,21The cost of ddPCR analysis of both mutations  was 9 USD if each sample was analyzed separately. However, if using the advantage posed by ddPCR, i.e., its capability to analyze two samples at the same time or two mutations in one sample, the reaction price drops to less than 7 USD. Most commercial laboratories at present use RT-PCR with a reaction price of approximately 18 USD . Where sequencers are used, the price is even higher. Nevertheless, if ddPCR was used and its capability of analyzing both mutations in a single properly utilized , it is possible to conservatively expect the price reduction compared to the current lowest prices by about 20%. The costs of the analysis of the two most common thrombophilic mutations (FV + FII) in the Czech Republic would, therefore, amount to approximately 45 USD. Considering the fact that every year approximately 50,000 women start to use contraceptives in the Czech Republic , the cosTaking into account the prevalence detected in our patient group, i.e., should the thrombophilic mutation be found in 6.1% of women, it would be 3050 women out of this cohort of 50,000  who would receive a recommendation to opt for other methods of contraception. Of these, at the prevalence of smokers of approximately 20%, 610 individuals would be recommended to cease smoking as well.The risk of a TED event is up to 35× higher  than in the general population in women using OCs and up to 100× (mean 90×) higher in FV Leiden heterozygotes and homozygotes using OC, respectively ,23. As tIn women who would, in addition to the above, be also smokers , the risk would be further synergistically increased, resulting in a 31× increased risk and 17.5× increased risk of a TED event compared to the general population for the 400 women with FV and 210 women with FII mutations, respectively. The individual risks and annual incidence of TED events in the considered cohort including literature sources are detailed in Calculations detailed in Besides the cost–benefit analysis at 100% compliance , we also calculated the savings at 80%, 50%, and 20% compliance and the break-even point , which was determined at 14.1% compliance. These values are presented in The aims of our study were to (i) determine the prevalence of the risk factors for TED in young women in the Czech Republic and (ii) on this sample, to evaluate the feasibility and cost-effectiveness of mutation screening with current state-of-the-art methods using the ddPCR instrument. Based on these results, we aimed (iii) to determine the impact of the knowledge about the presence of thrombophilic mutation on risky behavior  and (iv) to perform a cost–benefit analysis of screening for the presence of thrombophilic mutations in women planning to start the use of OCs compared to the treatment costs of TED patients .Up to 10% of women in the Czech Republic  have one of the two most common thrombophilic mutations ,29. ImprIn our study, there were 9 women with thrombophilic mutations (6.1%), two of whom were taking OC and two of whom were smokers. After being informed of the result, all four eliminated these undesirable risk factors (stopped taking OC and smoking) and generally started to address their lifestyle, knowing the consequences they may face in the future. Moreover, neither of the women who have had no additional risk factors at the time of the study  and were notified of the presence of thrombophilic mutations have started taking OCs or smoking since. The responsiveness to the information about thrombophilic mutations in our study was, therefore, 100%. However, this extremely high compliance may be caused by the population in our study, consisting entirely of female university students, who might be expected to have higher responsiveness than the general population. Such a high compliance, therefore, cannot be expected in the entire population, so we considered lower responsiveness in our calculations (see below).33% of the women analyzed in our group were taking OCs without the knowledge of their status of thrombophilic mutations and without the knowledge that a combination of these risk factors can lead to a significant increase in their risk of TED events. As mentioned above, the current guidelines do not recommend routine genetic testing of women before starting taking OCs ,15.The ddPCR method proved to be highly sensitive and suitable for screening in our study, proving the capability of analyzing even the sample with the lowest DNA concentration (3.47 ng/µL). This low value was likely caused by the manual isolation of DNA; should automated isolation be used, the concentrations would likely be rather at the upper limit of the range of DNA concentrations acquired during DNA isolation in our study. Nevertheless, the presence of a sample with such a low concentration only verified that ddPCR is highly sensitive—no analysis had to be repeated due to the low DNA content. Still, the fact that ddPCR is capable of analyzing two samples (or two mutations within one sample) in one run and one well remains its greatest benefit compared to other PCR techniques, saving the costs of chemicals . The metOur results indicate that, at 100% compliance, screening of the cohort of 50,000 women starting to take OCs every year in the Czech Republic for the presence of the two most common thrombophilic mutations could prevent 12 TED events every year; considering the average period of OC use (5.7 years ), this aThe presented study comes with limitations. The first limitation is a relatively small number of participants 148), which may have caused a relatively imprecise determination of the prevalence of thrombophilic mutations in the population. However, the result of our analysis (4.1% for Leiden V and 2% for prothrombin) is not far from prevalences reported elsewhere, although these were generally somewhat higher ,4,5,6,7.8, which The conservative approach was maintained also in the estimate of the possible target price using ddPCR under the circumstances of a massive screening program. Besides the reduction in costs of the analyses by approximately 20%, we should also take into account that over the course of the patients‘ lives, the genetic analysis is performed only once; this would make the later analysis of thrombophilic mutations, which would be likely performed in a relatively sizable portion of the population for various reasons, unnecessary. These costs should be, therefore, deducted from the screening costs . The knowledge of the presence already at a young age could possibly influence lifestyles beyond simple smoking cessation and OC avoidance, which could further benefit the healthcare system.There is, however, a known downside to genetic screening—namely, the stress which may burden women with thrombophilic mutations and reduce their quality of life due to the fear of impending danger of a thrombophilic event . HoweverIn our study, we only calculated with data known for the Czech Republic and/or, in the case of risk factors, Central Europe, which is genetically relatively homogeneous. As the risk factors for women carrying mutation while using OC and smoking at the same time were not known, we used a simple additive calculation instead of synergistic action . Risk factors for smokers were acquired from the study by Enga et al. . In addiAverage lifelong costs of TED treatment in the Czech Republic are approximately 234,000 USD per patient . This, hBesides, we have disregarded other risk factors for TED in our study, such as the environmental burden, which has been shown to also increase the risk of TED ,32. In tAccording to our results, the introduction of screening of young women prior to the first prescription of OCs could make sense as even a rough economical analysis without the consideration of the social dimension or mortality of young women at the beginning of their productive age) shows a major economic benefit.This pilot study proved to be highly useful for opening a discussion regarding the testing of thrombophilic mutations in young women planning to start taking OC. The presented cost–benefit analysis showed that such a screening would make sense  from the economical perspective as well; the financial benefit for the healthcare system would be maintained even if as few as 20% of patients in whom a thrombophilic mutation was detected avoided the use of OC.


There is ongoing interest in the alcohol industry to significantly reduce and/or add value to the liquid residue, vinasse, produced after the distillation and rectification of ethanol from sugar cane. Vinasse contains potassium, glycerol, and a protein component that can cause environmental issues if improperly disposed of. Currently, some industries have optimized their processes to reduce waste, and a significant proportion of vinasse is being considered for use as an additive in other industrial processes. In the manufacture of cement and asphalt, vinasse has been used in the mixtures at low concentrations, albeit with some physical and mechanical problems. This work is the first molecular approximation of the components of the sugar cane vinasse in an industrial context, and it provides atomic details of complex molecular events. In the current study, the major components of sugar cane vinasse, alone or complexed on the surface of calcium carbonate, were modeled and simulated using molecular dynamics. The results showed that the protein component, represented by the mannoprotein Mp1p, has a high affinity for forming hydrogen bonds with potassium and glycerol in the vinasse. Additionally, it provides atomic stability to the calcium carbonate surface, preserving the calcite crystalline structure in the same way potassium ions interact with the carbonate group through ion–dipole interactions to improve the cohesion of the modeled surface. On the contrary, when the glycerol molecule interacts with calcium carbonate using more than two hydrogen bonds, it triggers the breakdown of the crystalline structure of calcite expanding the ionic pair. Ethanol production from sugarcane is a thriving industry in tropical areas. The alcohol industry is expanding in proportion to population growth as consumption of chemical products, using ethanol as a diluent, follows population growth. However, as ethanol production increases, so does its by-product, vinasse, which is generated at a rate of 13 L for every liter of ethanol produced regardless of the industry ,3. The i+) as the major mineral component, glycerol as an intermediate product of alcoholic fermentation, and glutamic acid as the major amino acid [Vinasse is the liquid residue left after the distillation and rectification of ethanol. It is dark brown in color, with a high content of organic matter, acidic in nature, and has a characteristic odor . Physicoino acid ,6 of celCurrently, the alcohol industry has adopted several alternatives to modify the ethanol production process to make it more efficient. Among these alternatives, the use of reboilers in the distillation process allows a reduction of approximately 16% in vinasse production . Despite3).The problems associated with vinasse production have led to the industry considering alternative uses for the by-product. A promising avenue for the utilization of vinasse is its potential use as an additive in cement and asphalt production ,9. CemenIt has been reported that where cement mixtures were made with stillage concentrations lower than 10%, the physicochemical characteristics of the product were acceptable ,9, but a3 (the main compound used in cement manufacture). This study is also with the purpose of providing molecular knowledge, for the creation of more efficient and responsible additives with the marketed product and the environment.This study aimed to model, validate, and molecularly simulate stable chemical complexes formed among the components of vinasse, glutamic acid, glycerol, mannoprotein Mp1p, and surfaces containing CaCO3 ionic pair was obtained from the DrugBank database [The molecular modeling of each chemical complex  was conddatabase , under tThe Mp1p protein structure contained in the 3L1N data file was isolated from palmitic acid and molecularly modeled by changing selenomethionine (MSE) to methionine (MET); this was achieved by changing selenium into the S3 type sulfur atom, SD. The CG-SD and SD-CE bond lengths were set to 1.81 and 1.78 Å, respectively. This conversion of residues is important because the load charges and other parameters were available for MET, but not for MSE . Further3 and the crystalline structure of calcite, made up of four calcium ions in electrostatic interaction with six carbonate groups, were analyzed at the quantum mechanical level. The geometry optimization in the ground state was calculated applying the DFT [The chemical structure of CaCO the DFT ,22 using the DFT   [The validation of the molecular structures making up the chemical complexes was performed by a computational comparison of the 3D structures with the force fields listed in HARMM22)   groups are responsible for the formation of proteins, and these groups would be linked in a peptide [The orientation of the molecules to form the simulated complexes was developed for the GOL-GLU-K complex using the R-side-chain of glutamic acid, allowing for attractive and repulsive interactions. The hydrogens of carbon 1 (C1) in glycerol were oriented with the hydrogens of carbon beta of the R-side-chain of glutamic acid, allowing for a repulsive interaction at a distance of 1.84 Å. Similarly, the hydrogens of carbon 3 (C3) in glycerol were oriented with the unbound oxygen of the last carbon (CD) of the R-side- chain, allowing for an attractive interaction at a distance of 1.89 Å. Molecular orientation was developed through the R-chain of glutamic acid since the carboxyl (COOH) and amino  webserver, which uses molecules as probes to predict binding hot spots . The mosAll molecular complexes were solvated using water following the theTIP3P solvation models in a water box TIP3PBOX . Water mThe data on parameters and topologies were qualitatively analyzed using the Visual Molecular Dynamics software , and theThe simulations for 3A to 4D were configured in NAMD-Scalable Molecular Dynamics, which is a parallel molecular dynamics code designed for high-performance simulations  Table 1Table 1. All simulations were configured using energy minimization, and equilibration was done in 100 steps with the distance beyond which electrostatic and Van der Waals interactions were cut-off at 12 Å. Each molecular simulation lasted for 3000 ps at 1 fs per step. Temperature and pressure were held at 310 K and 1 atm, respectively.The minimization and equilibration simulations generated trajectories files that were analyzed by computing the root-mean-square deviation (RMSD) .Saccharomyces cerevisiae as a polymer complex, where glutamic acid (GLU) predominates as the constitutive amino acid of membrane proteins (3L1N) [Previous studies have shown that sugarcane vinasse is generally composed of potassium (K), an ionic element, glycerol (GOL), a major intermediate of alcoholic fermentation, and protein derived from s (3L1N) ,39.+. The K+ ion achieved stability that showed a deviation of approximately 1 Å compared to the GLU-GOL complex that fluctuated at approximately 1.5 Å  complexed with glycerol (GOL) and Kby FTMap . However3 molecular model . Additionally, the ion–dipole interactions between the oxygens in the isobutyl group in leucine and Ca2+ on the surface (C-O----Ca) were analyzed  throughout the simulation. The CaCO3 ionic pairs making up the surface exhibited an increase in molecular deviation because the glycerol molecules tended to separate the crystalline structure that made up the calcite, reducing particle size in a manner similar to that observed experimentally [The opposite case occurred when the glycerol molecule interacted molecularly with the surface of CaCOmentally . This at+ on the CaCO3 surface   .3 surface. This molecular behavior is consistent with studies where sugar cane vinasse was used as an additive in cement or concretes with positive results in physicochemical and mechanical properties [Finally, an analysis of the hydrogen bonds responsible for the stability of the surface, in a comparison between Simulation 4B and 4D, showed that the protein component (3L1N) remained with eighteen bonds throughout the simulation , avoidinoperties ,9,44.+ incorporated into the calcite through ion–dipole interactions together with the mannoprotein allowed for the correct cohesion of the mixture.However, the current molecular study showed that glycerol may cause mechanical problems, while KIt is important to highlight that this research work is constituted as the first molecular approximation of the components of the sugar cane vinasse in an industrial context and provides atomic details of complex molecular events. However, it is an approximation to the reality that has related limitations to each of the techniques used to model, optimize, and dynamize the molecules and complexes used.3 surface, the following conclusions were reached:After running twelve simulations, where chemical complexes were developed using the major components found in sugar cane vinasse and their interaction with CaCO+ and the glycerol molecules to a resistant mannoprotein of the cell wall in yeast.The literature currently reports a composition of amino acids in sugar cane vinasse consisting of fragmented yeast proteins as a result of the high temperatures obtained during vinasse production. It is necessary to characterize vinasse proteins, as the results of the current study showed a high affinity of K3 ionic pair as a starting point since it had low atomic deviations with respect to the crystalline structure of calcite. It was evident in all the validations of the molecular models and simulations that the calcite crystal is formed and is the most stable structure that prevents the expansion of the surface (cement).For the creation of a surface that simulates cement, the current study used the CaCOm/m) forms hydrogen bonds with the oxygen components of two CaCO3 ionic pairs, forcing it to break the crystalline structure of calcite, triggering surface instability. It is likely that the reported problems of adhesion and drying times in the use of stillage as an additive in asphalt and cement were caused by the glycerol content.Glycerol produced in the alcohol industry in proportions between 2.5 and 2.7% (m/m). The present study showed that K+ is incorporated into calcite through ion–dipole interactions and allows for the correct cohesion of the complex, which makes it a good additive for cement.The highest content of vinasse reported corresponds to potassium in ion form, which, depending on the industrial process, is approximately 4% (3 surface and tends to preserve the crystalline structure of calcite. In addition to interacting through hydrogen bonds with the surface, it can form natural polymers that improve the physicochemical properties of cement.Finally, the protein content in vinasse, which falls between 7% and 9%, is essential in the stability of the CaCO


Triticum aestivum L.), varieties of Lubava, harvest 2014-2018, Russia (the protein content was 12.5 ± 0.3 g/100 g in terms of humidity); dough and bread made from wheat flour , produced using the technology of plain bread, a classic recipe without improvers. Ultrasound-treated water with an exposure frequency of 22 ± 1.65 kHz and with a power variation of 252-630 W/l was used in test technology. The experimental data obtained made it possible to establish the intensification of the processes of swelling of wheat grain during soaking. In the experimental samples, after 8 hours of soaking, the loosened structure of the endosperm and evenly swollen components of the grain were observed, and the loop of the groove was closed. Activation of the processes of dough science was established, and gluten flour in the dough formed a single monolithic frame, in which the swollen starch grains are tightly packed. The interstitial walls of the crumb of the prototypes consisted of a solid mass of protein coagulated during baking, inside of which swollen gelatinized starch grains are interspersed, they are closely adjacent to the mass of coagulated protein with their entire surface, and therefore, there is no sharp, clearly visible boundary between them. The most pronounced changes in the structure of the dough and bread crumb were noted when using water, after ultrasonic water treatment at a power of 504 and 630 W/l. This method of exposure can be recommended as the best for obtaining good quality bread with less pronounced staling during storage.Visualization of the microstructure of the food matrix of both raw materials and the final product is one of the keys to understanding the processes occurring during its formation. It is the fixation of the results at the microlevel that allows us to form a hypothesis and then confirm it with the obtained array of experimental data. The presented study is aimed at studying the effect of ultrasonic water treatment on the change in the microstructure of wheat grain during its humidification. The article also presents the results of studying the microstructure of dough and wheat flour bread obtained using water after ultrasonic water treatment and the intensity of the processes of staling of finished bread in storage. The object of the study was grain of soft spring white wheat ( Numerous studies in recent years, in the field of ultrasonic exposure in the frequency range from 20 to 100 kHz, in the production of food products, prove its high effectiveness on the processes of formation of the food matrix. The mechanisms of ultrasonic exposure of various intensities allow you to adjust the technological parameters to intensify the production processes, improve the properties of the product, and increase the preservation of its properties during storage .Ultrasonic exposure, as a new technology of nonthermal treatment, due to such effects as cavitation, dispersing, and thermal, can be used to increase the production of biologically active compounds, including primary and secondary metabolites in plant-based foods , 7. The The mechanism of ultrasonic exposure is described in the works of several authors , 13. TheKim et al.  investigŞimşek  comparedLi et al.  used SEMThe above confirms the relevance and practical significance of using SEM to study the microstructure of the matrix of food products. Nevertheless, studies combining the effect of ultrasonic exposure in the process of water treatment on changes in the microstructure of wheat grain, dough, and wheat flour bread are still not well studied and presented in the literature and are of scientific interest.The aim of the study was to study the effect of ultrasonic water treatment with a power variation of 252–630 W/l on the change in the microstructure of wheat grain, dough, and wheat flour bread.Triticum aestivum L.), a variety of Lubava, harvested in 2014-2018, grown in the Ural region, Russia. The protein content was 12.5 ± 0.3 g/100 g in terms of humidity (Sample 1).This study used a grain of soft spring whitegrain wheat (Triticum aestivum L.), a variety of Erythrosperium 59, harvested in 2014-2018, grown in the Ural region, Russia. The protein content was 12.2 ± 0 : 3 g/100 g in terms of humidity (Sample 2).The grain of soft winter whitegrain wheat (The ingredients used to make the bread were purchased at a market in the city of Chelyabinsk. Refined wheat flour (RF)  was provided by the manufacturer OOO Soyuzpishcheprom, Chelyabinsk, Russia, and was used as the main raw material in the manufacture of bakery products.Yeast and salt were purchased in the retail network of the city of Chelyabinsk .We used USTA-0.63/22 OM  as an ultrasound generator with piezoelectric oscillation system in a metal frame with forced cooling (oscillation frequency was 22 ± 1.65 kHz and intensity range was 252–630 W/l). 4 power modes were used for processing: 252, 378, 504, and 630 W/l . The water was treated with ultrasonic exposure (ultrasound) with each power for 5 minutes; it was used for soaking wheat grains, kneading dough to make bread. Soaked wheat grain, dough, and bread samples obtained using drinking water were used as a control sample.The results of studies by the authors , 13 enabElectron scanning microscopy of wheat grain after soaking was carried out using a high-resolution scanning electron microscope with a Schottky cathode TESCAN MIRA3, equipped with a nitrogen-free Ultim Max 100 microanalysis system, controlled by Aztex Energy software. Preprepared sections of the studied samples with graphite deposition and a magnification of 150x, 2000x, and 3000x.The dough was prepared according to the method of Kim et al. , 17, witSoaking of wheat grain was carried out for 8 hours, in a hydromodule grain: water 1 : 1.25, at water temperature 20 ± 2°C . For soaThe test laboratory baking was carried out using the international method AACC 10-10.03 . The recThe amount of water was calculated based on the water absorption capacity of the flour at the rate of 650 E.F. (± 20) on the Brabender Farinograph equipment. The water temperature was 22 ± 2°C. The rheological properties dough were determined in accordance with the AACC 54-21.02 (2010) method on a Farinograph-AT . The volume of bread was determined by the seed displacement according to the method AACC 10-05.01, 2010. The bread was weighed, and its specific volume was calculated. The moisture content of the bread crumb was determined according to AACCI 44-15.02, 2010.The dough was divided by hand into portions of 450 g, and fermentation was carried out in a controlled fermentation chamber , at 30 ± 1°C and a relative humidity of 80% for 90 minutes. Baking was carried out in a laboratory oven  at 220°C for 20 minutes. The bread was cooled at 20 ± 2°C and tested after 3 and 72 hours.The studies were conducted in a fivefold repetition. The experimental data were processed on the basis of mathematical statistics methods using Microsoft Excel and MathCad. The obtained data are presented with a confidence factor of 0.95.To establish the effect of ultrasonic exposure on the changes occurring in the grain during its soaking, a study of microstructural changes in experimental samples of wheat grain was conducted. Considering the nature of water absorption by structural elements of wheat grain, described in the works of Miller and his colleagues , and theThe study of microstructural changes in control and experimental samples of wheat grain (Sample 1) was carried out after 8 hours of the soaking process, which is due to the achievement of the nominal value of the swelling rate indicator. Analyzing the results of SEM  of crossμm are noted in some areas. When using ultrasonic-treated water with a capacity of 378 W/l ; the results of which are given in The microstructure of sample f  has a laIt is known that the swelling of wheat grain is accompanied by a number of physiological processes: the respiratory activity of the grain is resumed, and protein synthesis from existing RNA occurs . When RNThe use of water treated with ultrasound also has a significant impact on the microstructure of wheat dough .To study the microstructure of dough samples after fermentation for 120 minutes, they were lyophilized and analyzed with preliminary platinum spraying in vacuum, recorded with an electron microscope of JSM-7001F (JEOL).The structure of both control and experimental  dough samples  is charaIn the control sample  are clearly visible in the microstructure of the control sample, which may indicate a decrease in the volume of starch grains due to the formation of the starch crystal structureExperimental samples obtained using treated water at 252 W/l and 378 W/l have a more uniform amorphous crumb structure, with a smaller number of air spaces. However, it is possible to distinguish starch granules in the samples and determine the pore size (AP)The observance of the changes of the microstructural indicators in control and experimental bread samples after 72 hours demonstrate the following:The most pronounced differences are characteristic of the sample obtained on water treated with ultrasound, with a capacity of 504 W/l . Its cruUltrasonic exposure (25 kHz) used in this study can be one of the effective environmental factors that stimulate the process of soaking wheat grains, forming dough and bread and wheat flour. The experimental data obtained made it possible to establish the intensification of the processes of swelling of wheat grain during soaking. In the experimental samples, after 8 hours of soaking, the loosened structure of the endosperm and evenly swollen components of the grain were observed; the loop of the groove was closed. Activation of the processes of dough science was established; gluten flour in the dough formed a single monolithic frame, in which the swollen starch grains are tightly packed. The interstitial walls of the crumb of the prototypes consisted of a solid mass of protein coagulated during baking, inside of which swollen gelatinized starch grains are interspersed, they are closely adjacent to the mass of coagulated protein with their entire surface, and therefore there is no sharp, clearly visible boundary between them. The greatest effect in changing the microstructure was established when using water treated with ultrasonic power of 504 and 630 W/l. Considering the importance and relevance of this study for the baking industry, we state that the studied method of water treatment will (i) accelerate the process of wheat grain swelling and producing flour from it, (ii) obtain a developed gluten matrix dough, and (iii) bakery products of high quality and long shelf life. Further research is recommended for active implementation of these studies in the food industry.The use of scanning electron microscopy made it possible to visualize the food matrix, which led to a better understanding of the essence of the described processes. It was the fixation of the results at the microlevel that allowed us to form a hypothesis, which in the future should be confirmed by an additional array of experimental data.


To protect magnesium alloy surfaces from wear and corrosion, an Fe-based amorphous coating was prepared on WE43 through the Ni60 interlayer by high-velocity oxygen-fuel (HVOF) spraying. The porosity was ~1%, and the amorphous content exceeded 90%. The wear and corrosion resistance of the composite coating with WC particles wrapped in a Ni layer as the reinforcing phase were compared with that of the completely amorphous coating. The friction coefficient (COF) of the composite coating was 0.3, which is only half of that of the WE43 substrate, and the composite coating exhibited a more stable wear behavior than the completely amorphous coating. The corrosion tendency of the composite coating is lower than that of stainless steel, with a corrosion potential of −0.331 V, and the addition of WC particles did not deteriorate the corrosion resistance considerably. The bonding mechanism of the bonding interface between the amorphous structure and the particles of the reinforcing phase was investigated by transmission electron microscopy (TEM). Reinforcing particles were confirmed to form metallurgical bonding with the coating. It was found that the Ni layer showed excellent bonding performance in the form of a mixture that is amorphous and nanocrystalline. Therefore, the Fe-based amorphous composite coating on a magnesium alloy surface shows a potential protective effect. Magnesium is an earth-abundant metal, and as a lightweight structural material, magnesium alloy offers high specific strength and high specific stiffness and is widely used in aerospace, automotive and sports equipment applications for low-weight design . ReplaciFe-based amorphous coatings are usually fabricated by thermal spraying, such as arc spraying (AS) , plasma mix = +18 kJ/mol), are immiscible in the solid and liquid state, as one of the key criteria for the formation of a solid solution is that ΔHmix must be between −20 and +5 kJ/mol [Fe and Mg, which have a positive enthalpy of mixing  and wear loss volumes than ordinary crystalline materials, such as 316 L stainless steel , but dueaterials ,18 have rication . Furtherrication , which prication  wrapped 2O3, on the surface of the coating is uniformly distributed without segregation in corrosive environments. In the corrosive environment where Cl− exists, pitting, microcracks and intersplats are recognized as Cl− enrichment areas, where Cl− leads to concentration increase in galvanic cells and accelerates the expansion and deepening of pitting through an autocatalytic effect [In an Fe-Cr system, Fe-based amorphous has an elemental composition and pitting corrosion mechanism similar to that of stainless steel. The initiation of pitting occurs when the anode material with low potential is preferentially corroded and dissolved after the galvanic coupling of the two materials with differenct corrosion potentials occur through the corrosive medium. Mg and inclusions, such as sulfide in stainless steels and segregation grains in Fe-based materials, are considered to have low corrosion potential and dissolve preferentially to form pitting after forming galvanic cells with a passivation film . The passive film with higher corrosion potential, such as Crc effect . Therefoc effect .In summary, this study is devoted to the fabrication of Fe-based amorphous composite coatings with reinforcing phase particles on a magnesium alloy surface by HVOF. The effective combination between the amorphous coating and magnesium alloy substrate was achieved by adding an Ni-based interlayer, and the interface bonding mechanism of amorphous/reinforcing phase particles was investigated.FeCoCrMoCBY powders prepared by high-pressure argon gas atomization  and Ni60 self-fusing alloy powders were used in this study. The chemical composition of the powders is summarized in 2 atmosphere after being polished and sandblasted with white fused alumina. Kerosene with a molecular weight of 154, a relative density of 0.825 and a combustion enthalpy of 45.1 J/g and oxygen as an accelerant were ignited by an HV-8000 high-velocity oxy-fuel spraying system . The main spraying parameters for the interlayer and coating are summarized in The Fe-based amorphous powders were screened by a sieve, and powders with a mesh size of more than 300 were used for spraying. The powder size was verified using Image J software . WE43 magnesium alloy with the size of 100 × 100 × 5 mm was used as the substrate and protected in an N2 atmosphere to reduce the thermal deformation caused by the temperature difference between the substrate and the spray particles. During the spraying process, the back of the substrate was cooled by N2 to provide the high cooling rate required for the formation of the amorphous alloy and reducing the oxidation and deformation of magnesium alloy. The composite coating was sprayed with a mixture of amorphous powders and Ni-WC reinforcing particles, in which the mass fraction (ω) of the amorphous powder was 85%.Before the spraying, WE43 was swept by a spray gun flame for preheating under an NThe phase microstructure of powders and coatings was characterized by an X-ray diffractometer  with Cu Kα radiation. The thermodynamic properties of the powders and coatings were quantitatively characterized by differential scanning calorimetry  to obtain the enthalpy change of the exothermic crystallization heat of the amorphous components when heated. Scanning electron microscopy  and transmission electron microscopy  coupled with energy dispersive spectroscopy  were used to observe the micromorphology and element distribution of the powders and coatings. The focused ion beam (FIB) technique is used to thin the coating interface area to accurately locate and analyze the bonding interface in the coating. The microstructure was determined by selected area electron diffraction  to determine the phase.2 ceramic ball with a diameter of 6 mm. The 3D model of the wear area was established by white light interferometer  to analyze the topography. The corrosion resistance of the coating was evaluated by Tafel polarization plots measured by an electrochemical workstation, with a scanning rate of 1 mV/s, using a three-electrode cell containing a saturated calomel reference electrode and a platinum counter electrode. The electrochemical polarization test was carried out in 0.1 mol/L HCl, before which the specimen was immersed in the solution to ensure the stability of open circuit potential (OCP). The WE43 magnesium alloy and SS304 stainless steel were also tested to compare the performance of the coating.The hardness at different areas of the coating cross-section was measured by a nanoindentation  test at room temperature, in which the target load was 200 mN. The friction coefficients (COF) of the substrate and coating were measured by a ball-on-disc friction and wear tester  at room temperature. The normal load was 20 N, the rotating speed was 400 r/min, and the friction pair was a ZrOThe SAED during the TEM shows a diffraction halo, indicating that the amorphous particles had a completely amorphous microstructure. The size of Fe-based amorphous particles followed a normal distribution, which was mainly concentrated in the range of 25–45 μm, according to the granulometric distribution statistics shown in The phase characteristics and thermodynamic analysis of the amorphous particles and HVOF coatings are summarized in oating/ωΔHpowders × 100% [The comparison of the XRD patterns showed that both coatings exhibited a broad diffuse peak representing the amorphous structure at about 2θ = 44°. There were no obvious crystal diffraction peaks in the amorphous coating, which was consistent with the SAED results. Crystal diffraction peaks in the composite coating matched the typical diffraction peaks of the Ni-WC particles. After quantifying the crystallizing enthalpies (ΔH) of the coatings in DSC curves, the amorphous fraction rate (R) of the coatings could be calculated due to the completely amorphous microstructure of the powders by the formula: R = ΔHs × 100% . AmorphoBoth the coating and the Ni60 interlayer formed a lamellar structure with a uniform thickness of –300 μm, according to the cross-sectional micromorphology shown in In the Ni transition layer of Area B, the hardness was as high as 14.6 GPa (less than pure WC), indicating that amorphous and Ni layer components were more likely to form intermetallic bonding due to the atomic diffusion, as shown in With the increase of wear time, the COF of WE43 increased gradually and fluctuated violently, finally increasing to 0.6, while the COF curves of the amorphous coating and composite coating were stable. In the initial stage of wear, the amorphous coating showed the lowest COF (~0.3), but the COF increased to ~0.35 after a sharp fluctuation in the intermediate stage, finally reaching 0.37. However, the COF of the composite coating fluctuated slightly at the beginning and then remained stable until the end. The 3D worn topography model clearly showed that the coatings had different furrows in The wear morphology of the coating surface after the different sliding times is illustrated in It is obvious from As shown in 3, Ni4B3 and Cr3C2 oxides containing Fe and Ni from the calibration of SAED. It is noteworthy that the position of point 4 was basically amorphous, and the elemental analysis in According to SAED, the coating remained completely amorphous, while the Ni layer existed in the form of mixed nanocrystals. It could be deduced that these nanocrystals were FeNicorr) than SS304 and much higher than WE43, indicating that the coatings had a lower corrosion tendency. The corrosion current (Icorr) of the corrosion coatings was less than that of SS304, while the current of the amorphous composite coating was the smallest, which was two orders of magnitude lower than that of the substrate. Both of the two coatings had a wider passivation region than SS304, and the amorphous coating had the best passivation performance because its passivation current is ~10−4.5 A, which is the minimum value of the passivation current of SS304. It is acceptable that Fe-based amorphous coating improved the corrosion resistance of the magnesium alloy surface, and the overall corrosion resistance performance was better than that of stainless steel.−1·K−1 for Fe, 90.9 W·cm−1·K−1 for Ni and 4.2 W·cm−1·K−1 for WC). Therefore, the temperature gradient at the micro-scale induced the precipitation of nanocrystals in the transition Ni layer with rapid heat conduction [3C2, Ni4B3 and FeNi3 began to precipitate one after another according to the priority of the formation tendency , but the nanocrystals that were fine enough in size were confined to a narrow formation area and did not result in serious crystallization of the coating. Thus, DSC enthalpies illustrated that the amorphous content of the composite coating decreased compared with that of the amorphous coating, but there was no obvious crystallization peak other than Ni-WC in XRD. However, due to the full spread of the Ni layer in The amorphous content of the coatings can also be controlled by adding other elements in addition to adjusting the spraying energy. It is generally recognized that Co can increase the deposition rate of coatings, thus enhancing the formability of amorphous coatings , Cr is tnduction . Cr3C2, mix with Fe and Mg of −2 and −4 kJ/mol, respectively, and so, the Ni60 interlayer had good compatibility with the coating and the substrate. At the same time, due to the high hardness, low thermal expansion coefficient and the elastic-plastic deformation resistance between the amorphous alloy and WE43, the Ni60 interlayer played a favorable transition role of relieving the stress and dispersing the thermal deformation between the coating and the substrate. The elements of the coating and the substrate were diffused into the interlayer, respectively, facilitating the formation of metallurgical bonding. This conclusion matches the existing literature [3, Ni4B3 and Cr3C2, which matched the ultra-high nanoindentation hardness. The same hardening behavior was also found in [The Fe-based amorphous alloy and the magnesium alloy do not dissolve and react with each other, but Ni has a ΔHterature , in whicfound in , where t3 to form between carbide grain boundaries. Studies [As a completely elastic-perfectly plastic solid material, Fe-based amorphous coating follows the plastic volume conserving characteristic, and so the indentation was deeper ,30, whil Studies  have shoAccording to the wear test and the previous test results of authors , the pro2 ball and carved furrows on the coating surface, as shown in 2 surface also began to break into fragments, and the coating surface started to undergo oxidation wear due to the accumulation of friction heat. Coated abrasive debris, ZrO2 fragments and oxidation products in the amorphous coating were embedded in the dents from the fatigue wear from 2 by a mass fraction can effectively reduce the wear of ZrO2-reinforced Fe-based amorphous composite coatings [If the melting of sprayed particles is not sufficient  or the pcoatings .As shown in R) is given by:w is the metal atomic weight, n is the number of charge transfer when metal corrodes, F is the Faraday’s constant and d is the density of the alloy, the CR has a positive correlation with the Icorr, so it could be inferred that the charge transfer of the composite coating was more active than that of the amorphous coating. The corrosion resistance of amorphous coatings is mainly based on microstructure uniformity and composition homogeneity. Therefore, the addition of Ni-WC inevitably led to inhomogeneity on the coating surface; thus, providing the prerequisite for the formation of galvanic cells. Fortunately, the Ecorr of the composite coating did not significantly decrease, indicating that Ni-WC particles did not change the overall corrosion tendency. The reason why the corrosion resistance of the composite coating did not decrease seriously may be that the filling effect of the reinforcing phase particles reduced the porosity to less than 1.22%, which has been reported as a key threshold for the Fe-based amorphous coating. Above this value, the corrosion resistance is more dominated by porosity, while below this value, it is dominated by the amorphous content. As mentioned above, if the second phase particles in the composite coating have an appropriate size, which is slightly smaller than that of the amorphous particles, they can fill the cavities and pores caused by the insufficient plastic deformation between the amorphous particles [- enrichment. The addition of Al2O3 has also been reported to reduce the infiltration of Cl- through the pores and suppressed corrosion of the coating in the NaCl solution [2O3-TiO2 particles, the corrosion resistance is not as good as stainless steel in an NaOH solution [According to the relation below , the corarticles , and thusolution . Howeversolution . CombineThe amorphous content of the composite coating exceeds 90%, and the porosity is approximately 1%. Compared with the completely amorphous coating, the composite coating is more dense and only slightly crystallized.The COF of the composite coating was 0.3, which is less than the 0.37 associated with the amorphous coating and only half of that of the WE43 magnesium alloy substrate. The Ni transition layer enhanced the bonding between the WC reinforcing phase particles and amorphous coating during wear and thus improved the wear resistance.corr and Icorr of the composite coating were −0.331 V and 3.582 μA, respectively, and the addition of the reinforcing phase particles did not significantly deteriorate the corrosion tendency and corrosion rate, which was still better than that of SS304 stainless steel and WE43 magnesium alloy.The EThe amorphous/Ni60 interface and the amorphous/WC interface in the composite coating have achieved favorable metallurgical bonding, where Fe and Ni were fully diffused. A mixture of amorphous and nanocrystals existed in the Ni transition layer, and the nanocrystals did not deteriorate the bonding properties but exhibited excellent mechanical properties.In this study, an Fe-based amorphous coating and an Fe-based amorphous composite coating were successfully prepared on the surface of a magnesium alloy by high-velocity oxygen-fuel spraying. Through the wear test, Tafel polarization plots and microscopic interface bonding mechanism analysis, the following conclusions were reached: