While dissociating surface acidic groups promoted the high dispersion of small metal species, carbon reactivity with oxygen and acidity limited the formation of the most catalytically active Co3O4. Formation of Co3O4 on the highly conductive carbon black resulted in an excellent performance with four electrons transferred and a current density higher than that on Pt/C. When Co3O4 was not formed in a sufficient quantity, nickel metal nanoparticles promoted ORR on the Ni/Co-containing samples. The activity was also significantly enhanced by small pores that increased the ORR efficiency by strongly adsorbing oxygen, which led to its bond splitting, followed by the acceptance of four electrons.Highly porous carbon black and micro/mesoporous activated carbon were impregnated with cobalt and nickel nitrates, followed by heat treatment at 850 °C in nitrogen. Detailed information about chemistry and porosity was obtained using XPS, XRD, TEM/EDX, and nitrogen adsorption. The samples were used as ORR catalysts. Marked differences in the performance were found depending on the type of carbon. Differences in surface chemistry and porosity affected the chemistry of the deposited metal species that governed the O So far, the most efficient catalysts have been those based on noble metals, and platinum dispersed on various conductive forms of carbons is considered as the benchmark of the catalytic performance [, and even to nonmetal catalysts [One of the factors governing the performance of fuel cells is the efficiency of an oxygen reduction reaction, which is determined by the number of electrons transferred as close as possible to four, an onset potential in the most positive range, small Tafel plot slope, and a high current density. In the specific catalytic reactions of oxygen reduction in either acidic or alkane electrolytes Hformance . Howeverformance , and eveatalysts ,5,6. Whiatalysts . The empatalysts , SAC, whatalysts . These matalysts . For foratalysts ,14,15,16atalysts ,27,28,29atalysts ,20, eithatalysts ,23,27, aatalysts , which hAnother catalytically important feature of the carbon materials is their porosity, which has recently been indicated as advancing the oxygen reduction process ,39,40,413O4 [Carbon blacks are a commodity of a highly conductive nature and they have been commonly used as supports for a high dispersion of noble metal-based catalysts ,45. Neve3O4 ,57 and o3O4 , can wor3O4 .2 [Recent works on various forms of carbon materials, including carbon blacks, activated carbons, carbon nanotubes, or carbon aerogels modified with cobalt and nickel as ORR catalysts have reported that the number of electrons transferred in alkaline electrolytes can reach four ; the ons2 . When a 2  and NiCo2 ,70.Published reports on Co and/or Ni-containing carbons as the ORR or bifunctional catalysts mainly link the catalytic activity to the content of metal on the surface and its dispersion, presence of nitrogen providing the coordination sites, and form/chemistry of Co and Ni species. Some of them analyze the effects of catalyst precursors . The mos3)2∙6H2O) and nickel nitrate hexahydrate (Ni(NO3)2∙6H2O) were used separately or combined in a 1 to 1 mass ratio of the salts to introduce metal-base active phase onto the carbon surface. BAX or BP was first impregnated with an aqueous solution of metal salt using a 1:1 mass ratio of carbon to salt . After drying, the mixtures were heated at 850 °C for 30 min, with a heating rate of 10 °C/min and under a nitrogen atmosphere (100 mL/min). The samples were then washed in a Soxhlet apparatus until constant pH and dried at 120 °C. Two series of three samples, BP-Ni, BP-Co, BP-NiCo and BAX-Ni, BAX-Co, and BAX-NiCo were prepared in this way, where the first term designates the type of carbon (BP or BAX) and the second term the kind of metal incorporated .Commercial carbon black from Cabot Corporation , Black Pearls 2000 (referred to as BP), and wood-based activated carbon from Ingevity , BAX-1500 (referred to as BAX) were used as catalysts supports. While BP was used as-received, BAX pellets were first ball-milled and sieved to a particle size below 212 μm. Cobalt nitrate hexahydrate (Co(NOBET (using the Brunauer–Emmett–Teller theory), and total pore volume Vtot . A volume of micropores, Vmic, was calculated using 2-NLDFT assuming the pore wall heterogeneity [mes was calculated from the difference between Vtot and Vmic.Nitrogen adsorption isotherms measured on an ASAP 2020  at −196 °C, after degassing the samples at 120 °C overnight, were used to calculate a surface area, Sogeneity . This meThermogravimetric (TG) and differential TG (DTG) analyses were carried out on an SDT Q600 . The samples were heated up to 1000 °C with a heating rate of 10 °C/min and under a 100 mL/min argon or air flow.XPS spectra were collected on a Physical Electronics  PHI 5000 VersaProbe II spectrometer  and a take-off angle of 45°). A concentric hemispherical analyzer operated in a constant-pass-energy mode, at 29.35 eV, with a 200 μm diameter analysis area. Multipack software was used to deconvolute the spectra.Resistivity of the materials was measured using a Keithley 2400 Multimeter  on a 0.5 × 0.45 cm gold interdigitated electrode covered with a thin film of carbon.TEM images were taken with a JEM2100 electron microscope  operated at a 200kV voltage. It is fitted with an Inca Energy Dispersive X-ray Spectrometer (EDX) system used to obtain the elemental maps.Oxygen adsorption in solution was measured by recording the concentration of dissolved oxygen in 50 mL water using a Hach  IntelliCAL LDO probe upon the addition of 250 mg of the carbon sample.2) coated with a catalyst ink (a thin film on the carbon disk was made of 33.3 μg of a sample and the same amount of Nafion binder) were used as a working electrode, a graphite rod as a counter-electrode, and a silver/silver chloride electrode (filled with 4 M KCl) as a reference electrode. Potentials EAg/AgCl measured were converted to potentials versus reversible hydrogen electrode, ERHE, using the following formula:Electrochemical measurements were carried out with a 0.1 M KOH electrolyte (pH = 13). A three-electrode system was controlled with a WaveDriver 40 bipotentiostat . A rotating ring-disk electrode (RRDE) with a gold ring and a glassy carbon disk (0.1963 cmCyclic voltammetry (CV) curves were measured at a scan rate of 5 mV/s after saturation of the electrolyte solutions with either nitrogen or oxygen gas.DL), assuming that they have a similar specific capacitance CS equal to that of carbon black, 27.5 µF/cm2 [Electrochemically active surface area (ECSA) of the samples was estimated from their double layer capacitance (C5 µF/cm2 :(2)ECSA=DL was calculated from the cathodic (Ic) and anodic (Ia) current measured at different scan rate between 5 and 150 mV/s in a non-faradaic region [Cc region :(3)CDL=ILinear sweep voltammetry (LSV) curves were recorded at various rotation speeds  in oxygen-saturated electrolytes while keeping the ring at a constant potential of 1.07 V vs. RHE. They were corrected for any capacitive currents by subtracting the background LSV curves measured in oxygen-free electrolytes.D, Il, and Ik are the disk, diffusion limited, and kinetic currents, respectively. They were divided by the carbon disk area, 0.1963 cm2, to obtain the corresponding current densities JD, Jl, and Jk.The kinetic current was calculated from the LSV curves, using the Koutecky–Levich Equation (3) :(4)1ID=12O2 produced from Equations (4) and (5), respectively [D and IR are the disk and ring currents, respectively, and N the collection efficiency of the ring-disk electrode is equal to 25.6%.The onset potential was calculated from the LSV curves measured at 2000 rpm using the unbiased second derivative method , and theectively :(5)n=4IDk|) was built in a region close to the onset potential and the slope was obtained by a linear fit.The Tafel plot of the potential as a function of log. That current density is higher than those measured on carbon blacks modified with cobalt reported in the literature [3O4 the current density reached 5.6 mA/cm2 [2 [2) was reported on carbon black with deposited carbonized Co2+, Zn2+, and 2-methylimidazole [x only 750 mV was measured [2, which is much higher than the kinetic current density measured on Pt/C (~35 mA/cm2). The results obtained on BP-Co are better than those reported in the literature on Co-modified carbon, [As expected, LSV curves  show thaterature ,71. For 6 mA/cm2 , and on midazole . The curmidazole . For themidazole , the dirmeasured , on tetrmeasured , and on measured . In term carbon, ,57,71,78 carbon, ,59,79,802. For this series, the comparison of the onset potential values points to the modification with Ni as the most efficient one and the onset potential on these samples being 90 mV less positive than that on Pt/C  in the case of supports with a low level of carbon ring condensation. It might also result in the development of an additional porosity. The deposition of salts, especially in large agglomerates, might also block some pores and decrease a pore volume and surface area determined by the N2 molecule.The presented above results of the electrochemical tests clearly show the effects of a carbon support on the performance of the catalysts. This performance is expected to be markedly influenced by resulting chemistry and the porosity of the catalysts influenced by the support. An important factor in our consideration is that the amounts of Ni and Co salts originally used for the modifications and the conditions of the treatments were the same for both series of samples. Therefore, any differences/trends in the surface properties should be linked to the effects of the carbon support and the interactions of their surfaces with deposited Co or/and Ni nitrate salts, and to the complex effects of the applied heat treatment on the resulting surface features. Following the general consensus, a surface rich in carboxylic groups is expected to increase the dispersion of metals, and the thermal decomposition of nitrates into NO2/CO during the thermal treatment in nitrogen. Obviously, more metal species on the surface of the BAX series did not lead to the higher catalytic activity.To understand the direction of surface chemistry and porosity changes that affect the final catalytic performance, we will first analyze the differences in the nature of the metal species deposited on the carbon surfaces. Even though these carbons were arbitrarily chosen owing to the specific micro/mesoporosity resulting in the high BET surface areas, they still differ significantly in other surface features. Burning carbon samples in air provides the information on the content of an inorganic matter, which in our case is considered to contain in majority nickel and/or cobalt oxides, remaining as a residue at 1000 °C. The comparison of TG and DTG curves measured in air is presented in 2 or Ni(OH)2, which leads to the formation of corresponding oxides that are reduced to metal between 500 and 700 °C. This process is reflected by sharp decreases in the weight. In the case of BP-Co, two steps are visible in this temperature range, suggesting the presence of cobalt in a higher oxidation state than +2, which was first reduced to CoO and then the reduction of the latter took place. The weight loss pattern for BP-Co suggests that hydroxide is present in a very small amount, or the particles of cobalt oxides are rather small and their reduction takes place gradually between 300 and 600 °C, with larger particles reduced at higher temperatures. The shape of the TG curve for BP-Ni rather suggests the less heterogeneous distribution of sizes than that for BP-Co, since a well-defined reduction event is detected at ~400 °C. The weight loss of BP-NiCo is apparently influenced by some mixed Co/Ni forms. For the BAX series, the comparison of the weight loss pattern of the modified samples with that of the initial sample should be performed only up to 600 °C, since it is the highest temperature that carbon was exposed to during its production. Gradual weight losses for BAX-Ni and BAX-NiCo suggest the presence of oxygen-containing particles of various sizes. The BAX carbon matrix reduces the majority of oxides between 500 and 800 °C and a two-step weight loss in this temperature range implies that some Co might be in a +3 oxidation state. In fact, the weight loss for BAX-Ni, and especially that for BAX-Co, resemble that for BP-Co between 600 and 800 °C; however, the reduction of the former sample starts to occur at lower temperatures, ~500 °C. The results of the thermal analysis in argon suggest that the particles of metal species/oxides on BP are larger than those on BAX, especially in the case of cobalt, and the particle sizes in the case of BAX are more heterogeneous in their sizes’ range.Some information about the differences in chemistry of the metal species can be provided by the thermal analysis conducted in argon, and the results, as TG and DTG curves, are presented in 3O4 with large crystals sizes of 27.5 nm, as calculated from the Scherrer Equation. The BP-Ni crystallographic phases are more chemically heterogeneous and broader than in the case of BP-Co diffraction peaks, and are assigned to Ni(OH)2 and metallic nickel crystals with sizes of about 6.2 and 6.9 nm, respectively. The presence of hydroxide in the case of BP-Ni is consistent with the sharp weight loss seen at ~300 °C on the TG curve of this sample measured in argon 2, and Co3O4 was used to deconvolute Co 2p3/2, keeping their relative positions, FWHM, and area ratios 2 is also detected and it explains the lack of well-defined weight loss on the BP-Co TG curve associated with dehydroxylation and two well-defined steps associated with the reduction of oxides. The chemical distributions of Ni on the BP and BAX samples are similar, but those of cobalt markedly differ between the series and BAX-Co, BAX-NiCo, and BP-NiCo have more Co(OH)2 than Co3O4, making BP-Co an outlier in terms of the Co3O4 content. On both BP-NiCo and BAX-NiCo hydroxides are in the predominant amounts. It is important to mention that on the BP samples nitrogen is detected in about 1 at.% and upon the treatment, its distribution changes and more nitrogen becomes incorporated to the aromatic rings, especially in the case of BP-Co. Regarding the carbon content on the surface, an increase in the detected relative content of carbon on BP can be explained by the presence of the discussed-above large particles of the metal species. Nevertheless, an increase in the contribution of carbon–oxygen bonds in the case of BAX supports mentioned-above oxidation and burn-off of the BAX carbon matrix by released NOx.As for oxygen, the BAX series also exhibits much more Ni and Co on the surface than does the BP series. As mentioned above, this is likely related to the larger particles of the metal species in the case of BP series. A 7 nm limit of the XPS surface analysis is not able to account for all metals and oxygen present in these particles, leading to their underestimated amounts. Ni 2p3/2 and Co 2p3/2 core energy levels were deconvoluted using multiplets based on the deconvolution approach of Biesinger et al. . A combi in Ref. ) fixed. 3O4 visible on the surface of BP-Co are formed by oxidation of CoO in large “islands”, existing due to the scarcity of oxygen-containing dissociating group, by NOx from the decomposition of nitrates. The metal contents in the BP series suggest that burn-off/activation of the surface during the preparation heat treatment occurred to a rather small extent. Highly dispersed Co(OH)2 formed on the functional groups remains on the surface, as a result of the contact of CoO with ambient air/moisture. In the case of BP-Ni, NiO from the decomposition of nitrates cannot undergo oxidation and remain on the surface in its original form or as Ni(OH)2. Here, the highly dispersed small particles of the nickel species are reduced to nickel metal. This is because NOx is able to oxidize only carbon, and formed carbon monoxide is a reducing agent to NiO. In the case of BAX, generally much smaller particles of nitrates were deposited on the surface and therefore the crystallographic phases are not well-defined. Here, Co3O4 is formed in a much smaller extent not only due the acidic nature of that carbon 2 and NiO particles are much smaller on the surface of BAX and the metal particles are smaller on BP. In the case of mixed metal samples, nickel is present mainly as hydroxides, as also detected by X-ray diffraction. Cobalt is also in majority as Co(OH)2; however, it exists in a highly dispersed form. The small particles of Co3O4 are also present and their contribution is slightly higher on BAX-NiCo than on BP-NiCo.Owing to the similarity in preparation, the discussed-above differences in the chemistry of the deposited metal species and in their distribution on the surfaces are expected to be mainly governed by the chemical features of the carbon matrices, which were discussed in detail elsewhere . Here, f98 of BP ) but als2 adsorbed on the modified BP samples decreased only slightly compared to that on the initial sample, for the BAX samples a significant decrease in the nitrogen uptake was found. As seen in <0.7) supports surface activation by NOx. On the other hand, over a 50% decrease in the volume of micropores indicates that the deposited species blocks an access of the probe nitrogen molecule to the small pores. The biggest decrease was found in the volume of mesopores and it might be caused by the deposition of the metal species on their surface functional groups, decreasing mesopore sizes markedly. The increase in the volume of ultramicropores is greater for BAX-Ni than that for BAX-Co, which supports the strong oxidation effects of NOx on the carbon matrix of BAX-Ni, as compared to that on the latter sample. In the case of BP samples the porosity of the modified samples is similar, although the nickel-containing sample still exhibits a slightly greater decrease in the surface area compared to that of BP-Co. In these samples some ultramicropores were formed, which could be due to the deposit of relatively large inorganic particles in supermicropores and in mesopores, causing a decrease in their sizes. Moreover, some slight effects of activation by NOx cannot be crossed out.The analysis of porosity of the materials tested might bring information not only on the dispersion of the metal phase and on the accessibility of the pores for the electrolyte with dissolved oxygen, but also on the activation/burn off processes taking place during the sample preparation, as speculated above. The measured nitrogen adsorption isotherms and calculated from them pore size distributions and presented in The pore size distributions presented in Another factor to consider as affecting the efficiency of the ORR process is the conductivity of the samples which significantly differs between the two categories of carbons tested. The BP series is much more conductive than the BAX series  and this certainly is related to the level of carbon aromatization/graphitization and the nature/amount of oxygen groups. The increased graphitization level of the carbon matrix by the heat treatment at 850 °C combined with the deposition of the metallic particles might explain an increase in the conductivity of BAX-Ni and BAX-Co, which positively affects the performance of these catalysts.2 upon its time-dependent dissolution in water. This might be related to the small sizes of cobalt Co+2 particles (other than Co3O4) on these samples, which might be undergoing oxidation to Co3O4, and those in situ formed catalytic centers  might be responsible for the higher stability of these samples compared to their Ni-containing and BP-based counterparts.The trend in oxygen adsorption from its saturated solution upon the addition of the catalyst is presented in The analysis of the differences in the surface features of our samples that are indicated in the literature as important to ORR, and discussed above, allow us to provide a plausible explanation of not only the good catalytic activity of the BP series and especially that of BP-Co, but also to suggest the surface features of the BAX series which result in its inferior behavior. The conductivity of the BP series is certainly their important asset, elevating the current compared to that on the BAX series. Another important feature of the BP series is the presence of nitrogen on the surface. Even in small amounts, that nitrogen, when incorporated to the carbon rings was indicated as enhancing ORR ,42,52,723O4 is the predominant species on the surface of BP-Co, we link the excellent performance of this sample to these species, which were also reported in the literature as catalytically active [Nevertheless, among the BP samples marked differences in the performance still exist, and BP-Co has been found to be the best catalyst, with the current density higher than that on Pt/C. Since the porosities and conductivities of the BP series are similar to each other, that effect can only be linked to the chemistry of the metal species deposited on the surfaces, in addition to the presence of those hypothesized above catalytic centers based on metal–nitrogen bonds. Since the analyses indicated that Coy active ,57. Suppy active .3O4 catalyst; however, on this carbon the catalytic action of these species is inhibited owing to overpowering effects of other factors contributing negatively to the efficiency of these series of carbons. The catalytic activity of Co3O4 has been previously linked to the coupling between the carbon surface and this species [3O4 activity in an acidic electrolyte.As also observed for the BP series, the BAX samples do not differ markedly in the porosity, and the difference in the performance between the samples in this series is expected to be predominantly governed by their surface chemistry. Here, the performance of both nickel-containing samples, BAX-Ni and BAX-NiCo, in terms of the onset potential is similar to that of the BP series, and taking into account all other features of these samples bringing catalytic disadvantages, this suggests that for this quantity the chemistry of the catalytic species is a predominant factor. In addition, the results imply here that the predominant feature governing the onset potential could be highly dispersed nickel and cobalt metal nanoparticles ,83. More species . Moreove species  based on3O4 was formed and it provided excellent catalytic activity, especially for the BP carbon sample whose surface was poor in dissociating groups. In that case an oxidizing action of NOx was directed mainly to oxidize cobalt and to form spinel Co3O4. The ORR catalytic efficiency of highly porous carbon black modified with cobalt was only inferior to Pt/C in the slightly lower onset potential, while the current density was much higher than that on Pt/C and the number of electrons transferred reached four with a high catalytic stability. The excellent performance of that carbon black was also linked to its high electric conductivity and porosity. The latter, by the high volume of ultramicropores, enhanced oxygen adsorption and thus provided a pseudocatalytic action complementing the overall influence of catalytic metal-based sites, and especially that of the Co3O4 particles. These results show promise in the application of commodity carbon blacks as ORR catalysts.The results collected show the significant effect of carbon matrix properties on the surface features of the catalysts, and thus on the catalytic performance of Ni- and/or Co-modified carbons influenced by them. The exact same modification procedure resulted in differences in the chemistries of the deposited species, in the sizes of the particles, and in the porosity of the materials. A more oxidized carbon surface, owing to the high density of oxygen groups attracting metal salts during impregnation, led to the high dispersion of metal species of small particle sizes, and thus promoted the formation of metal nanoparticles thorough reduction process, especially in the case of the modification with nickel, where the metal particles were found as promoting ORR. When cobalt was used as a modifier, Co


Thioredoxins (TRXs) are a class of ubiquitous and multifunctional protein. Mammal cells present three isoforms: a cytosolic and extracellular called thioredoxin 1 (TRX1), a mitochondrial (TRX2), and one specific in spermatozoids (TRX3). Besides, a truncated form called TRX80 exists, which results from the post-translational cleavage performed on TRX1. TRXs’ main function is to maintain the reduction–oxidation homeostasis of the cell, reducing the proteins through a thiol-disulfide exchange that depends on two cysteines located in the active site of the protein (Cys32-X-X-Cys35 in humans). In addition, TRX1 performs S-nitrosylation, a post-translational modification of proteins that depends on cysteines of its C-terminal region . These modifications allow the TRXs to modulate the protein function and participate in regulating diverse cellular processes, such as oxidative stress, transcription, signaling cascades, apoptosis, inflammation, and immunologic response. This points out the crucial relevance of TRXs for cell function, signaling it as a strategic target for the treatment of many diseases and its possible use as a therapeutic factor. Cur in cell ,4,5.in vivo mechanism is sensitive to temperature and can be inhibited by unknown factors present in the serum [Thioredoxin (TRX) is a small protein with reduction–oxidation (redox) properties found in a wide variety of organisms from bacteria to humans. Mammal cells present several isoforms: a cytosolic thioredoxin 1 (TRX1) ≈12 kDa), a mitochondrial TRX2 ≈18 kDa), and one specific in spermatozoids TRX3 (≈13 kDa). Human TRX1 and TRX2 are the best described, both isoforms possess two cysteines in their active site (Cys32-Gly-Pro-Cys35), but only TRX1 possesses three more cysteines in its carboxylic region that participate in proteins nitrosylation . On the other hand, human TRX2 possesses an extra signaling sequence of 60 amino acids in the N-terminal that functions as a guide for its transport to mitochondria  kDa, a m,6,7. TRX kDa, andhe serum ,11.This work shows the physiological processes where TRXs are involved and their modulatory role in cellular homeostasis and/or their involvement in the development of some diseases. Understanding the mechanisms of these processes points them out as possible candidates for the development of treatment strategies for diverse diseases.2TXN1 can be induced by a wide range of physicochemical stimuli, such as UV radiation, virus infections, the presence of hydrogen peroxide, and substances of metabolic origin, such as hemin, estrogen, prostaglandins, sulforaphane, and cyclic adenosine monophosphate (cAMP) [The gene encoding human e (cAMP) . It posse (cAMP) ,9,12  peroxidase. This folding is divided into different domains: an N-terminal domain with β-folded laminae aligned in parallel; another C-terminal domain, with folded laminae aligned antiparallel; and a third element, a coil formed by the α3 helix that binds the N-terminal and C-terminal domains. Their tertiary structure is formed by five folded β-laminae constituting a nucleus surrounded by four α helixes [TRXs’ secondary structure is characterized by a β helixes  , forming a disulfide bond between them and leading to the loss of its reducing activity. To recover its redox activity, it requires the thioredoxin reductase (TRXR) enzyme, which breaks the disulfide bond and reintegrates the thiol groups. TRXR is a homodimeric enzyme pertaining to the family of pyridine nucleotide-disulfide oxidoreductase. Its reaction mechanism with TRXs consists of a bimolecular nucleophilic substitution, which basically, transfers electrons from a reaction that starts with nicotinamide adenine dinucleotide phosphate (NADPH), passing over flavin adenine dinucleotide (FAD), to the active redox site of the TRXR, later, to the selenosulfide of the TRXR subunit, and, finally, to the disulfide of the oxidized TRXs ,10,14 F. There aTrx1 gene knockout murine model, where its absence causes lethal effects during early stages of development and in the morphogenesis of embryos. In contrast, overexpression of Trx1 confers a higher resistance to oxidative stress and an increase in life expectancy, pointing out the relevance it has in cell survival processes. Another example is the overexpression of Trx1 in the murine model of cardiac diseases, where its relevant role in essential processes for cardiac function has been demonstrated, participating in glycolysis, tricarboxylic acid cycle, beta-oxidation, the function of the mitochondrial permeability transition pore (mPTP), and the contractile apparatus of myofibrils. In the latter, oxidation of contractile proteins is the origin of the loss of plasticity and contractility of the cardiac muscle. It must be mentioned that the administration of TRX1 in these cases reverses the oxidative process and allows the cardiac muscle to recover its function [The relevance of TRXs for the correct cellular function is in examples like the function ,7.42H), sulfonic acids (–C–SO3H), S-nitrosylations (–S–NO), and glutathionylations (–S–SG) [Aerobic cellular metabolism induces the constant exposure to reactive oxygen species (ROS) and reactive nitrogen species, for example, those produced by the passage of electrons through the different constituents of the mitochondrial respiratory chain and those produced by phagocytic cells of the immune system. The existence of reactive species inside the cell may imply a risk factor for the integrity and cell function because of their high reactivity degree. Nevertheless, the permanence of these reactive species at low concentrations works as a regulator of important processes, such as cellular proliferation and survival. This regulating effect has its origin in the chemical modifications caused in proteins, among them stand out those undergone by some cysteines, the least abundant of the amino acids, and whose chemical properties allow them to significantly influence the function, structure, and activity of proteins. These modifications are diverse and include, mainly, oxidation processes of the thiol group forming sulfenic acids (–C–SOH) capable of forming inter- and intramolecular disulfide bonds, sulfinic acids (–C–SO (–S–SG) ,10,15,16High oxygen/nitrogen reactive species concentrations act as unspecific oxidants of many cell components, among them lipids, proteins, and nucleic acids. Because of the latter, it is very important for the cell to maintain a strict redox steady state of these reactive species, ensuring their correct function. To accomplish this task, there are enzymatic and protein mechanisms in charge of transforming the reactive species into less reactive and innocuous compounds for the cell. These detoxifying systems are essential for cells; hence, the diminution or inactivation of these systems results in the accumulation of reactive species that can lead to cell death ,15,17. TThe reducing capacity of TRXs is the main reason that allows them to participate actively in the regulation of many cellular processes. Under conditions of high oxidative stress, susceptible proteins and enzymes are oxidized at specific sites inducing alterations in their functions and, in occasions, their complete inactivation. In these cases, TRXs function as reducing factors that allow proteins to recover their functional state at the expense of the oxidation of the TRX itself ,18,19,20substantia nigra pars compacta (sNpc), which contributes to the deterioration of motor functions. The origin of this neurodegeneration is in the presence of abnormally folded protein aggregates, mainly α-synuclein. In this context, it has been hypothesized about the relationship between the formation of these aggregates and the decrease in the soluble ANT1 protein in the brain. Experimental results have also shown the presence of α-synuclein and ANT1 in the cerebral cortex of mice with the location of ANT1 in the center of these aggregations, suggesting that the phenomenon of aggregation of α-synuclein has ANT1 as an important factor [A couple of examples that illustrate the importance of maintaining the correct function of ANT1 are in Parkinson’s disease, characterized by the loss of dopaminergic neurons within the t factor . The sect factor . One mort factor .The potential of TRXs as regulators of different cell processes is evidenced even better with assays studying the possible reduction sites in proteins. The development of this type of technique in plants has yielded a good number of potential targets for TRX1, with proteins as diverse as those involved in ion channels, stress-responding proteins, and metabolism components . These results allow assuming an equally important effect in animal models and not only in plants . In huma5Through its redox activity, TRX1 can regulate different and very varied cell mechanisms. However, the presence of thiol groups, different from those located in the cysteines of the active site, grants it other regulating capacities through a reversible post-translational modification mechanism known as S-nitrosylation. Among the main cellular mechanisms regulated by S-nitrosylation are apoptosis; this results from the nitrosylation of cysteine residues in caspases 3, 8, and 9, the glyceraldehyde-3-phosphate dehydrogenase (GAPDH), the apoptosis signal-regulating kinase 1 (ASK1), the B-cell lymphoma 2, p53, FAS, and TRX1 itself  Figure .S-nitroglutathione reductase participate; the latter is a transnitrosylator of low molecular weight molecules. The transnitrosylation reaction carried out by TRX1 depends on the thiol groups present in both the TRX1 and the target protein, accompanied by the important fact that, in the process, TRX1 is also regulated in its function because of its nitrosylation [The global nitrosylation process of proteins is dependent on several factors, such as the presence or permanence of nitric oxide (NO) in the cellular environment, the concentration of this specie, location of the stimulus, the cellular moment at which the stimulus occurs, and the equilibrium between the nitrosylation and denitrosylation processes. The latter explains why, sometimes, the effects derived from the NO presence can be opposite, functioning in some conditions as an apoptotic signal and in others as an inhibitor signal of apoptosis. As main sources of intracellular NO are three isoforms of the NO synthetase: a neuronal isoform, an endothelial one, and an inducible one. ,28. Becasylation ,28 , interfering in the signaling process of its corresponding pathway . In addi6Protein degradation regulated by TRX1 occurs through several mechanisms that are dependent on its reducing activity. The first mechanism involves alteration in the ubiquitination process, which is a post-translational modification of proteins that depends on the binding of small ubiquitin polypeptides to the protein; in this case, TRX1 induces rupture of the thioester bindings between the ubiquitin and the thiol groups of proteins E1 and E2, interfering with the degradation process of proteins. In the second mechanism, TRX1 modifies the signals associated with the degradation of proteins, such as oxidation of specific cysteines inside the structure of proteins, avoiding the degradation of proteins. The third mechanism involves the modification of the activity of the proteasome 20S subunit, because this subunit is susceptible to the changes in the redox state and its activity depends on the presence of two disulfide bonds susceptible to be reduced by the action of TRX1, causing inactivation of that subunit. Another mechanism involves the lipid-phosphate phosphatase, phosphatases, and deubiquitinating enzymes, which possess cysteine residues that are critical for their catalytic functions and are also susceptible to oxidative processes. In this case, the TRX1 restores the redox state of the cysteines, which allows the proteins to recover their functionality. The reintegration process of the redox state of methionines gives a last example, once they have been oxidized to methionine sulfoxides, a process accomplished by the methionine synthase reductase and which is a target for the reducing action of TRX1 ,15,17.7Regulation of apoptosis by TRX1 is a well-described mechanism and shown to be extremely relevant for cell survival. As part of this mechanism, it is fundamental to know the function of the main regulator of the TRX1 activity, a protein known as thioredoxin-interacting protein (TXNIP), also called TRX-binding protein 2 or vitamin D3 up-regulated protein 1. TXNIP, through the reaction of its cysteines (Cys24 and Cys63 in human TXNIP), binds to the cysteines of the active site of TRX1, forming disulfide bonds between both proteins; this inactivates TRX1 and hinders it from becoming a substrate for TRXR. Under normal conditions, and in the absence of TXNIP, the reduced form of TRX1 binds to ASK1 protein, maintaining the latter inhibited and interrupting the signaling route for apoptosis. In turn, when oxidative stress prevails, TXNIP  mobilizes to the cytosol and mitochondrion, its presence causes the binding to TRX1, which releases ASK1 that can now be activated to trigger the signaling route for cell apoptosis ,30 Figu. Besides8Another important regulation mechanism carried out by TRX1 takes place during the genetic transcription process, where it causes changes in the redox state of some transcription factors, modifying their affinity for the DNA and affecting the expression of its target genes. Among the involved factors are the nuclear factor kappa-light-chain-enhancer activated B cells (NF-kB), the activator protein 1 (AP-1), p53, the polyomavirus enhancer-binding protein-2 (PEPB-2), the redox-factor 1 (Ref-1), the hypoxia-inducible factor 1-alpha (HIF-1), the histone deacetylase 4, and the glucocorticoids receptor. Of these, NF-kB and AP-1 are of interest because they influence the production of inflammatory molecules in macrophages ,28,31,32Besides, to the direct regulation mechanism of the NF-κB activity by TRX1, there is a second mechanism that causes the activation of some components within the MEKK1/JNK signaling cascade is the degrading IκB that is an inhibitor of NF-κB. The degradation allows the release and translocation of NF-κB to the nucleus, activating the transcription of genes through its interaction with factors, such as Ref-1, HIF-1, p53, AP-1, glucocorticoid receptors, and estrogen receptors. Regarding the cell response to estrogens, TRX1 acts like a factor that helps the estrogen receptor α (Erα) in its regulating role of genes expression; this regulation depends on the direct interaction between TRX1 and Erα ,14,15. A9TRX1 also acts on proteins that participate in the mitogen-activated protein kinase (MAPK)-dependent signaling cascades, which are highly conserved in all eukaryote cells. MAPKs are proteins in charge of performing specific phosphorylations in serines and threonines of their corresponding target proteins; the classic signaling route includes the participation of three proteins that perform phosphorylation in sequence; in the first step, a MAPK kinase kinase (MAP3K) phosphorylates and activates a MAPK kinase (MAP2K), then this MAP2K phosphorylates and activates a MAPK. Among the signaling pathways dependent on this mechanism are those that converge in the extracellular signal-regulated kinase (ERK), the c-Jun N-terminal kinase (JNK), and the p38 ,15,24,28Within the MAP3K family stands out ASK1, which is influenced by this redox state sensor mechanism. ASK1 is crucial in the cellular response to several types of stress. Human and murine proteins are composed of 1374 and 1379 amino acids, respectively; they possess an intermediate domain composed of a serine and a threonine that grant them the kinase activity and are activated by diverse stress factors, among them ROS, lipopolysaccharides (LPS), the tumor necrosis factor (TNF), and calcium input. Nonetheless, it is relevant to mention that the most important stimulus is given by the presence of ROS ,18. UndeThe relevance of the correct ASK1 regulation in cells is evidenced in the study with ASK1-deficient murine models; in these, an increase in the resistance to apoptosis induced by oxidative stress and a reduction in the sensitivity to the septic shock induced by LPS have been observed. In cultures of ASK1-deficient splenocytes, a diminution in the production of inflammatory cytokines, such as TNF, interleukin 6 (IL-6), and IL-1β, has been observed, suggesting that the ASK1/p38 axis exerts a critical role in the innate immune response. It has also been observed that the activation of the ASK1/p38 pathways induced by LPS diminishes if a pretreatment with antioxidants is provided, indicating that the LPS-dependent ASK1 activation is also mediated by the presence of ROS . Besides2O2, suggesting that the ROS-dependent interactions of TRAF6/ASK1 are crucial for the activation of ASK1 induced by LPS [TRAF2, aside from being an intermediate of the TNF-induced activation of NF-κB, functions as a protein that connects the TNF receptor with its signaling molecules. TRAF2 is associated with a MAP3K that activates the JNK pathways, as occurs also with ASK1 and MEKK1. In turn, TRAF6 is a critical regulator of NF-κB and the MAPK route during the activation mediated by the superfamily of the TNF receptor and of the family of Toll/IL-1 receptors. TRAF6 is also recruited to the ASK1 signalosome by the presence of Hd by LPS .3 activates its target in the signaling pathway Akt [Another example of the TRX1 regulation on the signaling cascade is found in the human phosphatase and tensin homolog on chromosome 10 protein (PTEN10), a 54 kDa protein known to be a suppressor of tumors and to function as a phosphatidylinositol-3,4,5-triphosphate capable of regulating cellular processes through its antagonist role to the phosphatidylinositol 3-kinase signaling. The PTEN10 avoids activation of the next step in the signaling cascade by hindering Akt, also known as protein kinase B, from undergoing the needed phosphorylations for its activation (phosphorylation at Thr308 and Ser473). In turn, Akt is a serine/threonine kinase involved in important cellular processes, such as survival, cell proliferation, angiogenesis glucose metabolism, and apoptosis; its activation is a fundamental process for the phosphorylation and activation of proteins, such as caspase 9, the NF-κB factor, and the protein Bcl-2-associated death promoter (BAD), which inhibits apoptosis ,32 Figu. These ihway Akt . In thishway Akt .An additional example of protein kinases regulated by TRX1 is in the protein kinase C (PKC), a kinase of the phospholipid-dependent serine/threonine kinases family that is involved in signaling pathways regulating cell growth, apoptosis, and response to stress. The PKC function is dependent on calcium and is mainly stimulated by a second messenger, diacylglycerol. However, it is also susceptible to the presence of ROS, the possible mechanism involves the selective oxidation of a cysteine-rich region contained in the regulator domain . Some PK10In vitro experiments suggest that TRX1 possesses co-stimulating activity with TNF, increasing the production of IL-6 and IL-8. It possesses chemoattractant functions for monocytes, neutrophils, granulocytes, and T lymphocytes. TRX1 activates monocytes and macrophages, is a growth factor for lymphoid cells, has a synergistic effect with IL-1 and IL-2, functions as a possible resistance mechanism against HIV-1, because TRX1 secreted by CD4+ lymphocytes, and reduces the disulfide bond on the domain 2 of CD4, which is important for the entry of the virus [In the immune response, TRX1 has also been shown to possess regulating functions with similar behavior to that observed for cytokines and chemokines. he virus . In humahe virus ,33.An alternative effect to that mentioned previously is in murine peritoneal macrophages; in them, the presence of TRX1 does not induce a change in the activation state of macrophages but exerts an amplifying effect of the activation process to the M2 phenotype. This phenomenon is a consequence of the increment in the production of IL-10 and CD206 interleukin markers (related with the M2 activation state) together with a diminution in the TNF and MCP-1 expression (related with the M1 activation state). The involved mechanism suggests the diminution in p16 expression, favoring the induction of macrophages toward the M2 phenotype, aside from the reduction in the AP-1 and Ref-1 expressions, which makes the macrophages less responsive to the activating stimuli of the M1 phenotype .An important immune regulation mechanism performed by TRX1 is that observed on IL-4; in this case, TRX1 reduces one of the three essential disulfide bonds for the IL-4 function, the one formed between Cys46 and Cys99. Rupture of this disulfide bond leads to the inactivation of IL-4, generating a negative regulating effect on the polarization of macrophages toward the M2 phenotype; this effect is specific for IL-4 and does not affect IL-13 .The study of cultures stimulated with migratory inhibitory factor (MIF) allowed determining that TRX1 binds to this factor, allowing for the formation of a protein complex that fosters the internalization of the extracellular MIF. Possibly mediated by the cluster differentiation 74 , the chemokine (C–X–C motif) receptor 2 (CXCR2), or the chemokine (C–X–C motif) receptor 4 (CXCR4) of the cell surface. Another level of regulation of the MIF activity could extend to the intracellular level, because for MIF to function as a cytokine it requires the formation of a homotrimeric complex linked through intermolecular disulfide bonds; this suggests that the cytokine activity of MIF could be regulated by TRX1, dissociating the complex .The chemotactic effect of TRX1 has been observed in the respiratory airways of rat, where its administration caused a 41% increase of neutrophils, a value quite above the values usually recorded in individuals without treatment (0.6%). This chemoattractant effect originates in the increased expression of TNF, the chemokine (C–X–C motif) ligand 3 (CXCL3), and the chemokine (C–C motif) ligand 20 (CCL20); being the increase in CXCL3 and CCL20 the key chemotactic factors . At the Another mechanism of the innate immune response mediated by TRX1 is the modulation of the complement at the endothelial level. The complement system is constituted by a series of proteins located in the serum that are activated in sequence to promote the formation of a protein complex called the membrane attack complex (MAC). MAC’s main function is the formation of channels in the cellular membrane that allow for the free diffusion of solutes between the cell cytoplasm and the external environment, which leads to the loss of cell homeostasis and, eventually, death. In this sense, TRX1 inhibits the activity of the C5 convertase (interfering with the production of C5a) and inhibits the activation of C9, hindering the formation of MAC. These inhibitory phenomena are interesting because they are not observed in the presence of TRX80 nor of other proteins of the TRX family, despite presenting the –CXXC– active site  Figure .The above examples point out the potential of TRX1 as a target or as a basis for the implementation of treatment strategies for diverse immunological diseases and alterations. However, it is important to analyze in more detail some of the unresolved mechanisms, like, for example, the cellular uptake mechanism. Regarding this topic, TRX1 uptake is a process of specific and saturable binding, suggesting the presence of some receptor or specific binding site not identified yet. Regarding kinetic details of the uptake process. The extracellular TRX1 is shown to attach rapidly to the surface of macrophages and, at 24 h, it can be located mainly in the lysosomal compartments .11TRX80 was identified as a factor that increased the eosinophils toxicity; therefore, it was named eosinophilic cytotoxicity enhancing factor. Human TRX80 is mainly produced by monocytes, it is 20 times more active than TRX1, it has been detected in the plasma at lower concentrations than those recorded for TRX1, and it must be pointed out that the concentrations of both proteins are not correlated. TRX80 is the product of an enzymatic cleavage performed on TRX1 between amino acids 80 and 84, losing its terminal motif αβ and hindering it to function as a substrate for TRXR; in addition, it lacks redox activity ,34. TRX1Besides the role of ADAM proteins in the secretion of TRXs and TRX80, it is important to consider the possible involvement of proteins like those involved in the oxidative folding of proteins as secretion mechanisms ,37. SincAmong the main functions described for TRX80 are its performance as a cytokine that stimulates the proliferation of monocytes (this effect has not been observed in B or T lymphocytes), as a chemokine for monocytes, T cells, and polymorphonuclear cells, and as a stimulator to produce proinflammatory cytokines ,27,33,34Although TRX80 lacks the inhibiting effect of TRX1 on the activation of the complement, its activating effect on the complement pathway, both in the classical and alternative routes, must be pointed out. This activating phenomenon is due to the direct interaction with C1q, properdin, and C4BP, causing the deposition of early factors in the complement activation pathway (C4b and C3). A result of this activation of the complement system is the production of anaphylatoxins C5a and C3a, which can bind to their corresponding cellular receptors, triggering effects, such as chemotaxis, vasodilation, activation of phagocytosis, and immunomodulation  Figure .12The study of the TRX/TRXR system in cancer cells has led to identify the direct relation between its overexpression and the aggressiveness of some types of cancer. In these cases, high TRX1 concentrations in blood during the disease have been observed, to record later normal values after excising the tumor, which emphasizes the relevance of TRX1 in the survival of tumor cells. Another example of the relevance of TRX1 is in the blocking of its expression in tumor cells, which causes the cells to behave less aggressively and even grow in cultures in the same way as would normal cells ,18. In t13N-acetyl group and an amide group. This design provides pertinent therapeutic advantages, such as easiness to permeate the inside of cells, the possibility to cross through the blood–brain barrier, and the ability to function as reducers of proteins that are usually the target of TRXs and to function as direct antioxidants in the neutralization of ROS [2), CB4 (NAc-Cys-Gly-Pro-Cys-NH2), and CB6 (NAc-Cys-Gly-Ala-Cys-NH2) peptides, which function as factors that reverse the oxidative stress in models of stress induced by the inhibition of TRXR in rats, being CB3 and CB6 the peptides with the highest activity [Involvement of TRXs in many cellular processes and homeostasis turns it into a relevant molecule for the development of treatment strategies of diverse diseases. Among these strategies are the synthesis of mimetic peptides, tri- or tetra-peptide sequences like the canonic sequence of the active redox site of TRXs blocked in both ends by an n of ROS ,40,41. Eactivity ,40,41. TOn the other side, peptides CB3 and CB4 have shown denitrosylation activity for several types of substrates by accepting a NO group from the substrate, forming the corresponding nitrosylated intermediaries (CB3-SNO and CB4-SNO). Aside from this denitrosylated activity, peptides also function as accelerators of the enzymatic reduction of nitrosylated proteins because both, the nitrosylated and the oxidized forms of peptides, are regenerated to a reduced state by TRXR and proteins with NADPH-dependent oxide-reducing thiols, in this way, joining the global process of enzymatic reduction . Becausein vivo and in vitro to diminish the oxidative stress in cells by inhibiting the phosphorylation of JNK and p38, avoiding the translocation of NF-κB to the nucleus. In diabetic rat models (Zucker diabetic fatty rats), CB3 diminishes the phosphorylation and activation of the MAPK signaling route, which diminishes the apoptotic process. In a model of human neuronal cells (SH-5Y5Y), CB3 and CB4 diminish excision of caspase 3, preventing the dissociation of PARP and reversing the phosphorylation of JNK induced by TNF [In addition, CB2 peptide administration in murine asthma models prevents the damage caused by ROS by inhibiting the activation of p38 and, thereby, avoiding the activation and nuclear translocation of the NF-κB factor ,41. Both14TRXs, through their redox properties and S-nitrosylating function, regulate the activity of many cellular processes needed for cell homeostasis, the general redox state of cells, and the modification of proteins and their functions. The inadequate performance of the TRX system compromises importantly cell homeostasis through either the loss of regulating mechanisms or establishing an uncontrolled oxidative stress state . The forThe type of modifications performed by TRX1 and the large number of target proteins that it contains place TRXs as a very relevant group of proteins for the study of many cell mechanisms and point to it as a possible candidate for the development of treatment strategies for diverse diseases. The continuous understanding of their functions and interaction mechanisms have allowed developing smaller molecules capable of performing their functions and representing important therapeutic advantages, like their greater permeability to the cell. Notwithstanding, there are several mechanisms that must still be detailed. For example, the unknown mechanisms involved in the secretion of TRX1 in the surface of cells (like phagocytic cells), the identity of the protein in charge of performing the cleavage of TRX1 that gives origin to TRX80, or the cellular site where this process is accomplished. Knowledge of these mechanisms would allow developing better strategies to modify specifically the production of these proteins aimed at influencing the described cell processes.


The degree of dedolomitization reaction in rocks cured in 80 °C, 1 mol/L NaOH solution was determined by quantitative X-ray diffraction (QXRD). The morphology of dolomites in rocks was determined by a polarizing microscope. The products of the dedolomitization reaction were determined by field emission electron microscopy (FESEM-EDS). According to the test results, the following conclusions are drawn. There is a good positive correlation between ordering degree and the molar fraction of MgCO3 of dolomites. When the MgCO3 mole fraction of dolomites varies from 47.17% to 49.60%, the higher the MgCO3 mole fraction, the greater the ordering degree of dolomite. By analyzing the degree of the dedolomitization reaction of different dolostone powders cured at 80 °C in 1 mol/L NaOH solution, it is found that the older the geological age of dolostone, the slower the dedolomitization reaction rate and the lower the degree of dedolomitization reaction. The lower the ordering degree of dolomite crystal in the same geological age, the faster the rate of dedolomitization reaction and the higher the degree of dedolomitization reaction.Dolostone is widely distributed and commonly used as concrete aggregates. A large number of studies have shown that there are significant differences in the expansibility of different dolostones, and the key factors determining the expansibility of alkali carbonate rocks have not been clarified. In this paper, rocks were selected from five different geological ages: Jixianian, Cambrian, Ordovician, Devonian, and Triassic ages. The ordering degree and the content of MgCO It is ocrystals . The ordcrystals ,8,9,10. crystals ,9,11. Gacrystals  analyzedcrystals  analyzedcrystals  used XRDcrystals  analyzedcrystals ,17 and Scrystals  studied crystals  studied crystals  analyzedIn this study, XRD and polarizing microscope are used to determine the microstructure of dolostones of different geological ages, and the influence of factors such as the ordering degree of dolomite crystal on the degree of dedolomitization reaction was discussed, which provided data support for exploring the ACR expansion law of dolostones. Identifying the types of rocks that are likely to cause damage can lead to the more efficient and rational use of resources.By consulting the 1:50,000 scale geological map of China and referring to the regional geological literature, the dolostones of different geological ages are determined. Twelve rock samples from five geological ages were selected for this experiment, as shown in 2 are below 10.0% except for rock JF. The content of Fe2O3 and Al2O3 in rock DJY is slightly more than 1%.The chemical analysis method of rock is carried out according to the standard GB/T 176-2017. The rocks are ground to about 60 μm to avoid damage to crystallinity caused by excessive grinding, dried and then XRD  was used to measure the ordering degree of dolomites. XRD data of rocks were analyzed through the Jade software. The integral intensity value I (015) and I (110) of the diffraction peak of the crystal plane of dolomite (015) and (110), respectively, were read ,22, and 3 and CaCO3, respectively, was calculated by using Formulas (2) and (3) [The d (104) value of the diffraction peak of dolomite (104) crystal plane on the measurement spectrum was read, and the mole fraction of MgCO and (3) ,24:MoleThe dolomite grain sizes in rocks of different geological ages were examined by thin slices of different rocks for optical microscope observation. About a hundred pictures were taken of each rock. A polarizing optical microscope  with transmitted light was used. The preparation of thin sections was performed according to the section “Thin section specimen preparation” [The dolomite powder was cured in the condition of 80 °C, 1 mol/L NaOH solution, and taken out regularly. After drying, ZnO was used as the internal standard for quantitative analysis by XRD, and then Jade was used to fitting and analyze the XRD pattern to obtain the peak area ratio of ZnO and dolomite, and the content of brucite was calculated by internal standard method. The degree of dedolomitization reaction in rocks is calculated by the ratio of the reduced amount of dolomite to the content of original dolomite, and the scanning speed is 1°/min, the scanning angle is 30~33°. Firstly, 5~10 mm rock particles were taken out after curing in 80 °C, 1 mol/L NaOH solution for 7 days. Then, rock particles were solidified in resin and polished by vibration polishing machine. After rough grinding, fine grinding, polishing, and drying for 24 h, the samples were observed by FE-SEM. 3 mole fraction of dolomites were analyzed by XRD to characterize the crystallinity of dolomite crystals. 3 mole fraction and ordering degree of corresponding dolomites. It can be seen from 3 of dolomites are significantly different in rocks of different geological ages.The ordering degree and MgCO3 mole fraction of dolomites. As can be seen from 3 varies from 47.17% to 49.60%, there is an approximately linear relationship between the MgCO3 mole fraction and the ordering degree of dolomite crystals. The ordering degree of dolomites increases with the increase in the MgCO3 mole fraction. When the molar fraction of MgCO3 of dolomite crystals is close to 50%, the order degree is higher. When the content of Mg2+ and Ca2+ in dolomite crystals is close to each other, Mg2+ and Ca2+ are more likely to be regularly distributed. Dolomite is formed in a low-salinity environment with a low ratio of Mg2+ to Ca2+, so the crystallization rate of dolomite is relatively slow, so the ordering degree of dolomite is high.The degree of dedolomitization reaction of different dolostones is different, and the reason for the difference is not clear. By analyzing the ordering degree of dolomites, the reason for the difference in the degree of dedolomitization reaction is explained. The influence of the morphology of dolomite on the dedolomitization reaction was discussed. The dolomites of rocks WMS-6, WMS-8, Bfl-7, Bfl-12, JF, DH-2, and DJY are mainly anhedral crystals. Among them, the degree of dedolomitization reaction of dolostones WMS-6, WMS-8, BFL-7, and BFL-12 is relatively low, and the degree of dedolomitization reaction is only about 40% at 14 d. The degree of dedolomitization reaction of dolostones DH-2 and DJY is close to 100% at 7 days. The degree of dedolomitization reaction of dolostone ZC, SFP-1, SFP-2, and SFP-3 with a good euhedral degree is close to 100% at about 14 d, and there is a great difference in the degree of dedolomitization reaction at the initial stage of dedolomitization reaction, among which, the degree of dedolomitization reaction of rock ZC reaches 59.1% at 4 d. However, the degree of dedolomitization reaction of rock SFP-2 is only 31.6% in 4 d. There is no correlation between the crystal morphology of dolomites and the degree of dedolomitization reaction, so the crystal morphology of dolomite in dolostones is not the key factor to determine the degree of dedolomitization reaction.3 mole fraction of dolomite crystals in the test rocks ranges from 0.4717 to 0.4960. With the increase in the MgCO3 mole fraction, the ordering degree of dolomite increases, and the relationship between the MgCO3 mole fraction and the ordering degree is approximately linear.The ordering degree of dolomite crystals in Devonian rocks is the highest, which is 0.83. The ordering degree of dolomite crystals in Jixianian, Cambrian, and Ordovician rocks is about 0.75. The ordering degree of dolomite crystals in Triassic rocks is the lowest, which is 0.61. The MgCOAfter curing in a 1 mol/L NaOH solution at 80 °C, the dedolomitization reaction rate of dolomite in 0.045–0.080 mm Triassic rock powders is the fastest, and the dolomite completely reacts at 7 days. The dedolomitization rate in the Jixianian rock powder sample is the slowest, and the dedolomitization reaction degree reaches about 40% at 7 days, and then hardly changes. The dedolomitization reaction degree of the dolomite in the Cambrian rock powder sample reaches about 50% at 10 d and then tends to be stable. The dedolomitization reaction rates of powder samples in Ordovician and Devonian rocks are similar, and the dolomites in the rocks can fully react after 10 days and 14 days, respectively. Therefore, it can be inferred that the older the geological age of rocks, the slower the dedolomitization reaction rate, and the lower the degree of dedolomitization reaction.The effects of the ordering degree of dolomites on the degree of dedolomitization reaction in different dolostones are analyzed. The lower the ordering degree of dolomite crystals in rocks of the same geological age, the faster the rate of dedolomitization reaction and the higher the degree of dedolomitization reaction.The products of the dedolomitization reaction of dolostones were determined by SEM-EDS, and the calcite and brucite were distributed around the dolomite crystals, and there were many tiny pores between the calcite and brucite.Through the study of rocks’ microstructure and dedolomitization reaction in dolostones of different geological ages, the conclusions are as follows.


The FSME contained three parts: as a feeding cell, a reacting cell, and a supplying cell. The flat Kynoar membrane was inlaid in the middle of the reacting cell, using the mixed solutions of petroleum and sodium hydroxide, with Tri (octyl decyl) alkyl tertiary amine (N235/7301) as the carrier in the supplying cell and the mine slops with Cr (VI) as the feeding section. The impact parameters of pH and the other ion density in the feeding solutions, the voluminal ratio of petroleum to sodium hydroxide solution and N235/7301 concentration in the supplying solutions were investigated for the obtaining of the optimal technique parameters. It was found that the dislodging rate of Cr (VI) could reach 93.3% in 215 min when the concentration of carrier (N235/7301) was 0.20 mol/L, the voluminal ratio of petroleum and sodium hydroxide in the supplying cell was 1:1, the pH of the feeding section was 4.00, and the Cr (VI) cinit was 3.00 × 10−4 mol/L. The practicability and steadiness of FSME were gained through the exploration of Cr (VI) adsorption on the membrane surface.A novel flat supplying membrane equipment (FSME) with a sodium hydroxide solution and a mixture of N235/7301 and petroleum has been studied for dislodging dichromate (which can be expressed as Cr (VI) or Cr Chromium is a rare refractory metal with excellent physical, chemical and mechanical properties. Chromium products are widely used in the fields of national economy, national defense construction and high-tech industry ,2. They Slops containing dichromate mainly come from the mining, beneficiation, metallurgy, electroplating and glass industries ,8. This Extraction technology and membrane technology are better methods to treat industrial heavy metal wastewater. In particular, membrane technologies have broad application prospects. Some scholars used the extraction method to dislodge the heavy metals and compounds, but the efficiency was very low and the effective use times were less ,23,24,25In this work, novel flat supplying membrane equipment (FSME) with mixed N235/7301 dissolved in petroleum and sodium hydroxide solvent was designed based on SLM to efficiently remove Cr (VI) from mine slops with high stability. N235/7301 was used as a carrier. The stability was enhanced and the extraction rate of Cr (VI) was significantly increased by the separation of the reacting cell with the feeding and supplying cells in the novel design. The selection of variable parameters was determined according to the research results of extraction technology and liquid membrane technology ,23,24,25The framework of FSME and its reaction mechanisms are shown in 6Cr2O7]; (c) the diffusion of metal-complex [([N235/7301]H)6Cr2O7] through the membrane from the limiting surface of membrane and feeding liquid of the feeding section to the limiting surface of the membrane and supplying the liquid of the supplying section in the reaction equipment; (d) [([N235/7301]H)6Cr2O7] decomposed into two substances into N235/7301 and Cr (VI) in the limiting surface membrane and supplying solution, according to chemical equation III in The synchronous dislodging process involves various (equilibrium) reactions : (a) theplex  is pH, that is, when the pH decreases, the removal efficiency of Cr (VI) also decreases. Also, when H+ increased, the formation of ([N235/7301]H+Cl−) 3 were used to simulate the industrial slops, and to investigate the effect of the initial ion-density in the feeding cell on the dislodging rate of Cr (VI). As shown in In the industrial slops, there always existed other ions, which may affect the dislodging of Cr (VI). Thus, the NaCl and KNOAs we described above, the mixed solutions in the supplying cell were a certain voluminal ratio of petroleum with N235/7301 to sodium hydroxide. To investigate the voluminal ratio impacts of the mixed solutions, the ratios of petroleum to sodium hydroxide were adjusted to 1:3, 1:3, 1:2, 1:1, 2:1 and 3:1, which was shown in 6Cr2O7] decomplexion, but also increased the concentration difference of H+ concentration in the feed part and the supply part of the reaction cell. Therefore, the diffusion of [([N235/7301]H)6Cr2O7] and recycled N235/731 was finally increased H)ncreased . When th6Cr2O7] in the membrane system. The higher opportunity of the diffusion and decomplexation of the [([N235/7301]H)6Cr2O7] increased the dislodging efficiency, as shown in In addition, the parameters of N235/7301 also have an important influence on the dislodging of Cr (VI). As can be seen from Equations I and II of We need to pay attention to the selection of the best conditions. We considered the price of materials. As for the price, if the removal efficiency was close under the two conditions, we chose the condition that uses less organic phosphonic acid membrane solution. Because the membrane solution is very expensive, too much membrane solution is not stable. Similarly, if the dislodging efficiency is similar under different acidity or alkalinity conditions, we choose the condition with less acid or alkali. This is because too many acids and bases are unstable.In previous studies using SLM to remove heavy metals, the retention of heavy metal ions on the membrane was observed ,13. In t6Cr2O7] in the interface between the membrane and the supply solution decreased with the increase of Cr (VI) in the supply solution of the reaction part. With the increase of operation time, the equilibrium was reached, and the adsorption of Cr (VI) was no longer increased. There was about 14% Cr (VI) on the membrane surface of the reaction tank. However, this has no negative effect on the supply of the membrane. As shown in This is because, as the running time increases, the rate of [([N235/7301]H)The running and the influencing factors of our new designed flat supplying membrane equipment (FSME) with mixed N235/7301 dissolved in petroleum and sodium hydroxide solvent for the dislodging of the Cr (VI) from the industrial slops was examined in the laboratory in this work. The results showed that FSME was able to remove Cr (VI) from the simulated industrial slops with high dislodging efficiency, using the mixed petroleum with the carrier of N235/7301 and sodium hydroxide (stripping solution) as the supplying solution. The optimal technology parameters were considered based on the effects of different impact parameters, with consideration of both the dislodging efficiency and the cost of chemical solutions and materials. The result represented the optimal parameters of the FSME, which were: the concentration of carrier (N235/7301) was 0.20 mol/L, the voluminal ratio of petroleum and sodium hydroxide in the supplying cell was 1:1, pH in the feeding cell was 4.00, and the running time was 215 min. Under the optimal conditions, the dislodging rate could reach 93.3%. Although there were many Cr (VI) ions detained on the membrane surface during the operation, the stable retention rate remained below 14% and did not hinder the reuse of the membrane, in which the removal rate of Cr (VI) was higher than 80%.However, the adsorption on the membrane surface should be further solved in the future in order to apply FSME in a wider range.


Manufacturers of building materials strive to optimize the three basic concrete properties—strength, durability, and shrinkage deformation, of which the focus is generally on the durability in the structure when designing and monitoring the poured concrete. Studying concretes’ structural performance and the change in their characteristics over time enables the solution of many important issues associated with the design of reliable, durable, and cost-effective buildings and structures. This article presents studies aimed at improving the physical, technical, and operational characteristics of cement concrete and reducing cement consumption in heavy concretes through the use of complex modifiers and volumetric fiber reinforcement. Four concrete compositions of widely recognized grades were developed, of which samples were molded and tested for compressive and flexural strength, frost resistance, volumetric water absorption, and density. Test results confirmed the possibility of binder (cement) economy up to 18% and increasing frost resistance up to W300 when using microsilica, reduction in volumetric water absorption of up to 40% when using both microsilica and hyperplasticizer, and increasing flexural strength by over 30% when using polymer fiber. The developed compositions passed the industrial tests, and were successfully introduced in the production process of the operating reinforced concrete products’ manufacturer. From d cement . Moreoved cement ,7. In prd cement , used bod cement . Complexd cement ,10. ThesEffective heavy concretes of various functional purposes with improved building and operating properties are produced using multicomponent compositions . The cre2 crystals—which is important for the manufacture of dense and durable concrete [Active mineral additives significantly affect the basic physical and technical properties of concrete, giving it improved characteristics contributing to more efficient use of chemical energy from clinker by creating additional centers of crystallization. The number of stable hydrosilicates increases due to the reduction in the most unstable component of cement stone—Ca(OH)concrete . Analysiconcrete . The surconcrete . To obtaconcrete .One of the promising ways to improve the physical, technical, and operational characteristics of concrete is the introduction of polymeric fiber ,20. The To improve the technological properties of concrete mixtures by reducing their water content, improving their workability, and increasing their homogeneity and resistance to stratification, by using a complex modifier consisting of a hyperplasticizer based on polycarboxylate ester and ultradispersed active silica;To reduce the shrinkage deformations of concrete in the early stage of curing and increase the flexural strength of cement concrete through the use of volumetric fiber reinforcement with low-modulus polypropylene fiber, in order to improve the crack resistance and quality of products.Analysis of the aforementioned literature and the experience of the authors of this article—accumulated over several years of inspection work at the plants for the production of reinforced concrete products, along with systematic observations of the products during operation—show that it is very important not only to obtain concrete with highly desirable characteristics, but also to maintain those characteristics during the period of operation . AccordiThe purpose of this study was to improve the physical–technical and operational characteristics of cement concrete and reduce cement consumption of mainstream grades of heavy concrete by using complex modifiers and volumetric fiber reinforcement. This goal was achieved by using complex multicomponent compositions and obtaining high-quality concretes of different functional purposes with improved building and operational properties.2) that bind hydrolyzed lime to additional amounts of strong cementitious calcium hydrosilicates. In parallel, by creating additional crystallization centers, the issue of increasing the durability of concrete was addressed.The main technical task of this study was to reduce the proportion of cement in the composition of concrete. This necessity is dictated not only by the reduction in energy intensity in the production of Portland cement and the reduced consumption of fuel and electricity in the extraction, processing, and handling of raw materials, but also by the most pressing issue—significant carbon dioxide emissions during the firing of carbonate raw materials. This task was solved based on the theory of creating additional crystallization centers by using reactive pozzolanic additives  ratio and increase early and final strength indicators of concrete, increasing frost resistance and reducing the volumetric water absorption index of concrete while maintaining a given flowability, according to the basic law of concrete strength , throughThe task of enhancing the deformation properties and cracking resistance of concrete by using dispersed polypropylene fiber reinforcement was the final task of this study. Here, of particular interest was the dependence of the effect of fiber on the compressive strength and flexural strength of popular grades of heavy concrete with different binder consumption and water–cement ratios.Selection of compositions of modified heavy concrete of popular grades, as described in ;Determination of the basic strength characteristics  at the design age of 28 days;Determination of basic performance characteristics ;Comparison and analysis of test results of modified heavy concrete of mainstream grades.This study used both theoretical and empirical research methods. Theoretical research aimed to calculate the compositions of modified heavy concrete using the equation of absolute volumes and compare the results with existing compositions of heavy concrete of popular grades, determining the direction of the work, focusing on cement saving. Empirical studies were aimed at experimental confirmation of theoretically developed compositions. Furthermore, studies of physicomechanical and operational properties of the obtained modified concrete of popular grades were carried out. The studies were carried out in 4 stages, each of which was aimed at solving a specific task:This study used local raw materials. Portland cement CEM I 52.5 N manufactured by Heidelberg Cement  in Kazakhstan was used as a binder for the studied concrete mixtures. Several tests were carried out to confirm the compliance of the chosen binder with the regulations and requirements of . The metThus, the investigated binder showed a grinding fineness of 97.4%. Its normal density was 26.3%. The beginning of the setting was in 2 h 11 min, while the end of the setting was in 4 h 10 min from the moment of mixing. The values obtained were compliant with the standard. In determining the strength characteristics, the binder under study showed a bending strength of 6.1 MPa at the age of 28 days, in compression at 53.7 MPa. The obtained parameters corresponded to the standard.Sand from the manufacturer Giyada LLP , meeting the standard of , was useCrushed stones of 5–10 mm and 10–20 mm fractions produced by Baltabay LLP , with known physical and technical characteristics, were used in the coarse aggregate. This aggregate meets the requirements of , which dCondensed compacted microsilica CCM-85 manufactured by Tau-Ken Temir LLP  was used as a reactive pozzolanic additive, as described by .A chemical additive based on polycarboxylate esters of the 2nd generation AR Premium described by , produceLow-modulus polypropylene fiber of different lengths from Fibro-Lux LLC  was used for volumetric reinforcement in the studies, as described by , with thThe structure of further studies was to compare the indicators of physical–technical and performance characteristics of the modified concrete of popular grades, obtained by mathematical calculation using the equation of absolute volumes, and experimentally confirmed by laboratory mixes and studies of physical–technical and performance characteristics at the design age of 28 days. All studies and tests were conducted following interstate standards ,35,36,37Formulation of technical specifications which, in addition to the conventional requirements for concrete strength and workability of the concrete mix, must contain the minimum allowable value of its ultimate extensibility, based on the conditions of formation and, therefore, the expected or measured value of the possible deformations;Selection of raw materials and obtaining the necessary data characterizing their properties, including the water consumption of aggregates;3;Calculation of the concrete mix composition to determine the consumption of key components in kg per 1 mExperimental verification of the obtained composition and its adjustment (if necessary).The calculation involved four steps:bR was determined according to its dependence on the cement activity cR and the W/C ratiok and n are coefficients depending on the type of concrete and the quality of aggregates, respectively. For heavy concrete, n = 1.5; when using crushed stone, k = 3.5; for gravel, k = 4. This equation is valid for calculating the strength of densely placed concrete, cured under normal temperature and humidity conditions and tested by the standard method at the age of 28 days.The concrete compressive strength 3) was determined using Equations (2) and (3). The sum of the consumption of components is numerically equal to the average density of the concrete mixture, expressed in kg/m3. The calculation of the composition was based on solving a system of equations for fine-grained (Equation (4)) or heavy (Equation (5)) concrete, which include mathematical expressions that are already known and widely used in practice, such as the basic law of concrete strength, the equation of absolute volumes, and the separation factor of aggregate grains, which together can provide the relationship of consumption and the properties of the main components with the concrete strength and workability of the concrete mixture.Next, the consumption of coarse and fine aggregates (kg/mRb is the given concrete strength (MPa);h.CSV is the hollowness of crushed stone in bulk condition;pk is the coefficient of aggregate grain separation;bd.CSp is the bulk density of crushed stone;ρnd.CS is the natural density of crushed stone; Rc is the cement activity (MPa); A is the coefficient counting the quality of aggregates; C, W, S, CS, and F are the consumption of cement, water, sand, crushed stone, and fiber, respectively, per 1 m3 of concrete (kg) (fiber consumption is determined by indicators of workability by test batches);ρC, ρS, and ρCS are the grain density of cement, sand, and crushed stone, respectively (kg/m3);r is the ratio of sand and crushed stone consumption, which is assigned based on the grain composition of aggregates .The concrete compositions were then experimentally validated during laboratory batching, after which control samples of concrete were made and tested for the corresponding characteristics.As part of the compression and tensile tests, specimens were molded in the forms 2FK 100 and FP 100, according to the standard in , from thThe flexural strength of concrete was calculated with an accuracy of 0.01 MPa using Equation (6):F is the breaking load (N);a, b, and l are the width and height of the cross-section of the prism beam, and the distance between the supports, respectively, in the flexural test of samples (mm);δ is the scaling factor for converting the strength of concrete to the strength of concrete in samples of basic size and shape; WK is the correction factor for cellular concrete, taking into account the moisture content of samples during the test .After obtaining data on the compressive strength and calculations of the flexural strength of samples, the dependence of the influence of modifiers and volumetric fiber reinforcement on the flexural strength was determined.The test to determine the frost resistance was carried out via the second accelerated method described in ; the samAfter obtaining data on frost resistance, the dependence of the effect of modifiers and volumetric fiber reinforcement on the concrete frost resistance was defined.Tests to determine water absorption in concrete were conducted as described in , where csM is the mass of the water-saturated sample (g), and dM is the mass of the dry sample (g).The water absorption of each concrete sample WM (% by mass) was calculated with an uncertainty of up to 0.1%, using Equation (7):After obtaining the water absorption data , the dephttps://docs.cntd.ru/document/1200115733 (accessed on 26 February 2022) [Tests to determine the average density of concrete were conducted according to Russian State Standard GOST 10181–2014—Concrete Mixtures; methods of testing are available online at ry 2022) —where thρW (kg/m3) of concrete of each sample in the series was calculated with an error of up to 1 kg/m3 using Equation (8):m is the mass of the sample (kg), and V is the volume of the sample (m3). The average density of concrete was calculated as the arithmetic mean value of the test results of all series samples.The average density After obtaining the average density data , the effThe summary in The diagram shows that the use of modifiers allows cement consumption to be reduced while maintaining the workability of the mixture. Thus, for compositions No. 2 and No. 3, cement consumption was reduced by 14.1%, 17.1%, 19.5%, and 15.4% for concretes B25, B30, B35, and B40, respectively, while for composition No. 4, cement consumption was reduced by 12.8%, 15.9%, 18.4%, and 14.3%, respectively.The use of a polycarboxylate-ester-based hyperplasticizer reduced the W/C ratio of the compositions , therebyThe next stage of the study was laboratory tests of the selected compositions to determine their physical, technical, and operational properties .According to In 2 microsilica).The test results of the modified concrete in The strength results show that the obtained characteristics correspond to the normative values. Thus, concretes with modifying additives and volumetric fiber reinforcement show more than 30% increase in flexural strength, which is a highly significant indicator, as the improvement of deformation properties and cracking resistance of concrete by using dispersed reinforcement with polypropylene fiber was the ultimate task of this study.Comparing the obtained results with the achievements of previous studies ,39,40, t3), with better performance in terms of density, frost resistance, and volumetric water absorption, which indicate the best operating characteristics. Thus, when producing concrete sleepers with B40 graded concrete, the application of concrete mix modified with microsilica as 10% of the binder allows savings of up to 70 kg of cement per 1 m3, i.e., to reduce the consumption of expensive cement CEM I 52.5 N per 1 m3 from 455 kg to 385 kg, while maintaining all strength characteristics as specified in Russian State Standard GOST 10181–2014—Concrete Mixtures; methods of testing available online: https://docs.cntd.ru/document/1200115733 (accessed on 26 February 2022) [Based on numerous laboratory and industrial tests, it can be concluded that the use of modified concretes is justified both economically and scientifically. Unlike ordinary compositions of concrete, modified concretes allow significant savings of cement (up to 100 kg per 1 mry 2022) . Application of hyperplasticizers based on polycarboxylates is justified by several positive effects at once, such as water reduction—i.e., reduction in W/C ratio—and correspondingly increasing strength characteristics according to the basic law of concrete strength, improving the physical properties of concrete, increasing density, and reducing permeability, which follows from indicators of volumetric water absorption, while also improving the surface quality of products.One of the main strength indicators of concrete and a characteristic sought in implementing these studies is the flexural strength, as the main purpose of introducing fibers is to improve the characteristics of concrete under flexural loads. Thus, according to the study results, it can be concluded that the use of low-modulus polypropylene fibers in optimal quantities is justified in terms of improving the weakest characteristic of concrete—flexural strength .From the above conclusions, the use of modifiers and dispersal reinforcement can be recommended to reduce the cost and improve the deformation and operational properties of heavy concrete.Volumetric fiber reinforcement improves the physical–technical and deformation characteristics of existing reinforced concrete mixes, in particular increasing the flexural strength by over 30%. Volumetric fiber reinforcement with low-modular polypropylene fiber of concrete mixtures can be recommended to produce reinforced concrete products.The effect of using low-modulus plastic fiber in the frames of high-rise buildings is that it increases the flexural strength which, consequently, reduces the consumption of steel reinforcement and the cross-section of concrete partitions. Accordingly, all of these measures reduce the load on the foundation of a high-rise building.After obtaining positive results from laboratory tests, production testing of the developed compositions was carried out at the plant to manufacture reinforced concrete Firma-BENT LLP . After confirming the effectiveness of the compositions and real savings of binder in production conditions, the reinforced concrete plant included the developed compositions of concrete in its technological maps. These compositions are recommended for use in their working program to produce reinforced concrete products.