In addition, we report several characterization techniques such as ultraviolet-visible spectroscopy (UV-Vis), dynamic light scattering (DLS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) in order to correlate the properties of the polymer with the metal nanoparticle size and the catalytic activity. A volcano plot was observed linking the catalytic performance with hydrolysis degree and the maximum of the curve was identified at a value of 60%. The Au:PVA-60 weight ratio was changed in order to explain how the amount of the polymer can influence catalytic properties. The effect of nitroaromatic ring substituents on the catalytic mechanism was examined by the Hammett theory. Moreover, the reusability of the catalyst was investigated, with little to no decrease in activity observed over five catalytic cycles. Morphological and kinetic studies reported in this paper reveal the effect of the PVA polymeric stabilizer properties on the size and catalytic activity of supported gold nanoparticles.The effect of polyvinyl alcohol (PVA) stabilizers and gold nanoparticles supported on active carbon (AuNPs/AC) was investigated in this article. Polymers with different molecular weights and hydrolysis degrees have been synthesized and used, like the stabilizing agent of Au nano-catalysts obtained by the sol-immobilization method. The reduction of 4-nitrophenol with NaBH Metal nanoparticles of different sizes, shapes, and compositions are of high interest in fields such as catalysis, nanomedicine, and pollution remediation ,3,4,5,6.The properties resulting from the combination of dimensional and quantum effects allowed the use of gold nanoparticles (AuNPs) in catalysis, which is in contrast with bulk gold that has a long-standing reputation of being an inert metal. In 1980, Haruta et al. ,11, the 4 can be considered as a model reaction for the evaluation of its catalytic activity. The reaction occurs at room temperature and ambient pressure, without the formation of side-products, and the conversion can be easily monitored by UV-visible spectroscopy. The reaction presents a high activation barrier due to repulsive forces between 4-nitrophenolate anion and the hydride used as a reducing agent. In the absence of a catalyst, kinetics is extremely slow, this allows making assessments on the real catalytic efficiency of supported metal nanoparticles . In. Inn, shn = 23,300), but varying the hydrolysis degree, in order to elucidate the influence of this parameter on the nanoparticle size, morphology, and dispersion on the support. PVA2 and PVA-88 products were used to complete the study since they are commercially available at the same molecular weight. Moreover, PVA2 was called PVA-99 in order to homogenize the name inside the series. Spectroscopic studies performed by UV-visible analysis showed a shift of the plasmonic resonance peak toward the red region of the spectra, in agreement with the decrease in the hydrolysis degree. The reason for this behavior can be due to the smaller number of hydroxyl groups, which allowed the growth of the nanoparticles. In fact, the valuation of the plasmonic shifting described an increase in the Au nanoparticle size (0). The peaks are composed of spin-orbit doublets . They have characteristic binding energy peaks at 83.8 and 87.5 eV for Au 4f7/2 and 4f5/2 electrons, respectively , the particle size is bigger, and consequently, the percentage of exposed Au surface is lower, as well as the kapp. Although an increase in the average nanoparticles size of Au and a different percentage of exposed gold could suggest a great variation of their catalytic performance, it is evident that all catalysts showed a low activity. This trend was probably due to the site-blocking effect produced by the great amount of the hydroxyls group, which minimizes the diffusion of 4-nitrophenolate on the nanoparticle surface.−2 min−1. This value was more than ten times higher than the catalyst prepared with 1:0.65 (1.8∙× 10−4 min−1) and 1:0.33 (3.9∙10−4 min−1) weight ratio of Au/PVA  was chosen based on the small average nanoparticle size of Au to investigate the effect of this parameter. The catalytic performance was enhanced when the Au/PVA weight ratio was decreased. The supported Au nanoparticles obtained with an Au/PVA weight ratio of 1:0.15 presented an apparent kinetic constant of 5.3 × 10f Au/PVA , Table 8The catalysts synthesized using PVA2  with different Au:PVA weight ratios were characterized in order to explain the observed catalytic performance. DLS analysis showed an increase in the hydrodynamic volume, due to the decrease of the polymer amount around the nanoparticles. Moreover, the increase in the size is due to the smaller efficiency of PVA as a stabilizer which is influenced by the smaller amount of PVA present in the solution. From TEM analysis, an increase in nanoparticles size was observed for the sample prepared with a low amount of polymer . Moreoven = 23,300) in the range of 20% to 99%, in order to evaluate its influence on the catalytic activity (app increased as the mean particle size of Au was decreased from 9.6 to 3.9. The decrease in nanoparticle size and the decrease in the amount of exposed gold may explain this trend. Upon further increasing the hydrolysis degree from 60% until fully hydrolyzed PVA (99%), the rate of the reaction decreased due to the formation of the bond between the solvent molecules and the hydroxyl groups, which inhibit the catalytic activity. Based on the catalytic studies after optimization, the Au/AC sample with PVA-60 as the desired hydrolysis degree was chosen to conduct the following studies. Subsequently, the Au/PVA-60 weight ratio was further studied and optimized in order to choose the optimal amount of polymeric stabilizer. The Au/PVA-60 weight ratio was varied from 1:0 to 1:1.2 while maintaining the other experimental parameters. As depicted in app was increased from 0.2 to 0.3 min−1. The other values were lower than the kapp values observed at the Au/PVA-60 weight ratio of 1:0.65 . The Au:PVA weight ratio was studied in order to evaluate how the amount of the polymer can influence the availability of active sites. The sample with a 1:0.33 ratio resulted in the best catalyst in terms of activity. The effect of substituents on the aromatic ring was investigated and the 3-nitrophenol was the most reactive substrate due to the absence of resonance and inductive effect. Reusability tests were conducted on the PVA-60 with an Au:PVA ratio of 1:0.33 and a little variation was observed in activity after five catalytic cycles. The synthesized catalyst result was very efficient and thereby showed a high potential for a variety of catalytic and environmental applications. In addition, these findings emphasize the importance of ligand−nanoparticle interrelationships in the catalytic mechanism of supported nanoparticles.The results obtained in this study demonstrate that polymeric stabilizers influence the nanoparticle size and activity of supported gold nanoparticles. Several characterization techniques were used to characterize AuNPs synthesized using PVA with a low molecular weight and high hydrolysis degree. Although the presence of a high amount of hydroxyl groups enhanced the stability of the gold colloidal solution, the catalytic activity was inhibited due to the steric and electronic effects of the polymer chains. The study also shows that a volcano plot was obtained by correlating the PVA hydrolysis degree with apparent kinetic constant relative to 4-nitrophenol reduction. The maximum was identified in the sample synthesized with PVA hydrolyzed at 60% (M


At the edge of the joint, the stirred layer in which the A6061 matrix and the galvannealed layer are stirred also forms. Moreover, the solidified part of the residual melt discharged from the joint area forms at the outer peripheries of the joint. In this study, FSSW was conducted for two total welding durations: 9 and 10 s. Although the thickness of the remaining A6061 sheet in the welded area decreased with an increase in the welding time, the effects of the total welding time on tensile shear and tensile shear fatigue properties were negligible. A fatigue fracture occurred in the A6061 matrix and at the joint interface at the high cycle fatigue region and the low cycle fatigue region, respectively. In the case of the interfacial fracture, the crack was generated in the solidified part of the residual melt or at the interface between the solidified part and the stirred layer.The microstructures, tensile shear properties, and tensile shear fatigue properties of dissimilar A6061/Galvannealed steel joints fabricated by friction stir spot welding (FSSW) were investigated. Fe Making car bodies lightweight is expected to reduce carbon dioxide emissions as a method of slowing global warming . Thus, mIn particular, to combine steel and Al alloys in the car body, fastening with a rivet (self-piercing riveting (SPR)) ,14, laseIn contrast, although the RSW method has been used in the welding of steel for car bodies, it is not easy to apply it in a dissimilar bond due to differences in melting points, thermal conductivities, coefficients of thermal expansion, etc. between materials. Additionally, the formation of Fe–Al brittle intermetallic compounds (IMCs) in the joint interface exerts a bad effect on the reliability of the joint ,19,20. SUnder such a background, friction stir spot welding (FSSW) is expected to be a new method to overcome the above-mentioned problems. The FSSW method is derived from the FSW method. The FSW method has been already applied to the welding of dissimilar Al alloys , dissimi7, Fe, and Zn were detected from the galvannealed layer. Thus, it was confirmed that the main reaction phase in the galvannealed layer of the GA980 sheet investigated in this study was FeZn7.An A6061 alloy sheet (Al–Mg–Si system) and a GA980 galvannealed steel sheet were prepared as an Al alloy and steel, respectively. The thicknesses of the A6061 sheet and the GA980 sheet were 1.6 and 1.4 mm, respectively. The thickness of the plating layer of the GA980 sheet was approximately 7 μm. FSSW was conducted using a pin with a Φ2 mm tip diameter at 3000 rpm. This parameter was referenced from that used in a previous study that conducted FSSW of an A6061 alloy and hot dip galvanized steel ,31. FiguA tensile shear specimen shown in The tensile shear test was conducted using a universal testing machine . The cross head speed and test temperature were 5 mm/min and room temperature (R.T.), respectively. Two specimens were tested in each welding condition. After the tensile shear test, the fracture mode was analyzed using the laser microscope and the EPMA. Moreover, XRD analysis was conducted on the fracture surface of the specimen, which showed an interfacial fracture to investigate the formation phases in the joint interface.6 level. After the tensile shear fatigue test, the fracture mode was analyzed using the laser microscope and the EPMA.The tensile shear fatigue test was conducted by load control using a sine wave with a fatigue testing machine . The frequency, stress ratio, and test temperature were 10 Hz, 0.1, and R.T., respectively. The test was conducted at load amplitudes of 1.5, 2.7, 4.0, and 5.0 kN to obtain a fatigue life at the 104Al13 [4Al13 has also been reported in a previous study in which transmission electron microscope observations were conducted for a dissimilar aluminum/steel joint using the variable polarity cold metal transfer technique [For the interfacial reaction layer formed in the FSSW joint shown in 4Al13 . The for4Al13 . The forechnique . A simil4Al13 was detected in both fracture surfaces, and thus, it was confirmed that Fe4Al13 phases form at the joint interface. In the FSSW process, the oxide film of A6061 is destroyed due to plastic flow of the softened A6061 matrix and due to heating by frictional heat, and thus, the active nascent surface is exposed. According to the Fe–Zn phase diagram [7 that is the main component of the plating layer of galvannealed steel is from 530 to 665 °C and the eutectic temperature of Al-Zn is 381 °C. Plastic flow at the stirred area has been reported to occur at approximately 400 °C in the friction stir welding of the A1100 sheet and the SS400 mild steel sheet [7. From 4Al13 forms on the Al-rich side, liquid (L)+Fe4Al13+(Al), L+Fe4Al13, and L+Fe4Al13+(Zn) form on the FeZn7-rich side depending on the ratio of Al and FeZn7, and thus, the L phase appears at the welding interface. Once such an L phase is removed from the welding interface by pressure and rotation of the pin and shoulder of the FSSW tool, both active nascent surfaces of A6061 and GA980 make contact and are bonded in solid state, and thus, the reaction layer including Fe4Al13 forms at the joint interface.To identify the IMC formed at the interfacial reaction layer, an XRD analysis was conducted to the surfaces ruptured by interfacial fracture during the tensile shear test described later. The results of the XRD analysis are shown in  diagram  and the  diagram , the trael sheet . Since t7, the eutectic reaction with Al in A6061 and Zn in the galvannealed layer occurs and, thus, the eutectic melt is generated. Thus, liquation cracking is possibly generated in this study. Therefore, the microcracks observed in the edge area where the melt is discharged seem to be generated by liquation cracking. A similar microstructure was also observed in the joint welded at the welding time of 9 s.At the edge that corresponds to (E) shown in The results of the tensile shear test are shown in 4Al13 were observed at area (C′). The areas (B) and (B′) are the A6061 side and the GA980 side at the edge of the joint, respectively. Only the stirred layer was observed at area (B), and the stirred layer and Fe4Al13 were observed at area (B′). In addition, area (B’) was rolled up similar to a hangnail. The area was deformed by the tensile shear test. The areas (A) and (A′) correspond to the outer peripheries of the joint. In area (A), white BSE phases are observed. Those phases are solidified parts of the residual melt that is discharged. In area (A′) as well as area (B′), the stirred layer and Fe4Al13 were observed. From these results, the crack was confirmed to be generated in the solidified part of the residual melt or at the interface between the solidified part of the residual melt and Fe4Al13 and mainly progresses at the interface between the stirred layer and Fe4Al13. Additionally, the crack passed the interface between the stirred layer and the A6061 matrix at the center of the joint. Moreover, a rupture of the A6061 matrix was also observed at the edge between areas (A) and (B).To investigate the details of the fracture mode in the interfacial fracture, a cross sectional observation was conducted for the joint ruptured by interfacial fracture. L-N) diagram in the tensile shear fatigue test are shown in L-N diagram is negligible. When the number of cycles to failure is more than around 105 cycles, fatigue fracture occurred in the A6061 matrix regardless of the welding time. The load amplitude and the number of cycles to failure 4Al13 phases form as the IMC layer at the joint interface between the A6061 matrix and the galvannealed layer of GA980 consisting of FeZn7, Fe and Zn. At the edge of the joint, the stirred layer, which consists of the A6061 matrix and the galvannealed layer, forms between the A6061 matrix and the IMC layer. Moreover, the solidification of the residual melt discharged from the joint area occurs at the outer peripheries of the joint.Fe(2)4Al13 and mainly progressed at the interface between the stirred layer and Fe4Al13.An analogous tensile shear force was obtained regardless of the welding time, although the thickness of the remainder of the A6061 sheet in the welded area decreased with an increase in the welding time. In the tensile shear test, the crack generated in the solidified part of the residual melt or at the interface between the solidified part of the residual melt and Fe(3)5 cycles, fatigue fracture occurred in the A6061 matrix. In contrast, at the low cycle fatigue region in which the number of cycles to failure is less than 105 cycles, interfacial fracture occurred. In the case of the interfacial fracture, the crack is generated in the solidified part of the residual melt or at the interface between the solidified part and the stirred layer and progresses in the stirred layer and the interface between the stirred layer and the IMC layer.Analogous fatigue properties were obtained regardless of the welding time. At the high cycle fatigue region in which the number of cycles to failure is more than around 10(4)5 cycles, the dissimilar FSSW joints investigated in this study are superior or equal to those of the dissimilar FSSW joints with Al alloy and steel investigated in previous studies.For the fatigue strength of 10In this study, a sound dissimilar FSSW joint with an A6061 alloy sheet and a GA980 galvannealed steel sheet was fabricated for total welding times of 9 and 10 s using a stepwise welding force profile. The microstructures, tensile shear properties and tensile shear fatigue properties of the FSSW joints were investigated. The results obtained are summarized as follows:


With the attention paid to the heritability of breast cancer, the search for the genetic susceptibility gene of breast cancer has become a hot spot. At present, a number of studies have explored the relationship between rs13347 polymorphism of cluster of differentiation 44 (CD44) gene and breast cancer, but the research conclusions are inconsistent. Therefore, we will use this meta-analysis to explore the role of this gene polymorphism in breast cancer susceptibility.The search time is set from the establishment of the database in March 2021 in this study. The search database include China National Knowledge Infrastructure, Wanfang, VIP Information Chinese Journal Service Platform, and China Biology Medicine disc, PubMed, EMBASE, Web of Science and the Cochrane Library. The subjects are observational studies on the relationship between rs13347 polymorphism of CD44 gene and breast cancer . The language is limited to English and Chinese. The data of the included study are extracted and the literature quality is evaluated by two researchers independently. The data are statistically analyzed by Stata 16.0 software.Based on the existing studies, this study will systematically evaluate the relationship between CD44 gene rs13347 polymorphism and breast cancer.This study will provide evidence-based medical evidence to clarify the role of CD44 gene polymorphism in breast cancer, and provide help for the early detection and preventive intervention of breast cancer.Private information from individuals will not be published. This systematic review also does not involve endangering participant rights. Ethical approval will not be required. The results may be published in a peer-reviewed journal or disseminated at relevant conferences.DOI 10.17605/OSF.IO/WBC7F Due to the delay in diagnosis, the number of patients with advanced breast cancer has increased. Previous studies have shown that early diagnosis of breast cancer can significantly improve the survival rate of patients, but the current clinical lack of effective means of early screening. Studies have confirmed that breast cancer has genetic susceptibility. Exploring the relationship between genes and breast cancer will contribute to the early diagnosis and prevention of breast cancer.Breast cancer is a common malignant tumor in women. According to the statistics released by the World Health Organization in 2018, breast cancer is the first malignant tumor that threatens the health of women in the world. The new cases of breast cancer in the world are more than 2 million. In 2018, the incidence and mortality of female breast cancer are 46.3 /105 and 13.0 /105 respectively, and are on the rise. Many studies have shown that CD44 is involved in many key processes of cells, including cell growth, reproduction, differentiation, adhesion and migration.,7 CD44 is also a common tumor marker, which is closely related to the proliferation, migration and invasion of tumor cells, and participates in tumor-related angiogenesis. Studies have found that CD44 is widely expressed in a variety of cancer cells, affecting the prognosis of the disease, and the specific knockdown of CD44 will inhibit the occurrence and development of cancer.Cluster of Differentiation 44 (CD44) is a multistructural and multifunctional transmembrane glycoprotein, which can be used as a receptor for hyaluronic acid and many other extracellular matrix components, as well as for a variety of growth factors and cytokines.–12 the conclusions are still controversial. Some studies have found that the polymorphism of the rs13347 site of the CD44 gene increases the risk of breast cancer, and some studies have come to the opposite conclusion that the polymorphism of the rs13347 site of the CD44 gene reduces the risk of breast cancer. In order to explore the source of this difference , and to clarify the relationship between CD44 gene rs13347 polymorphism and breast cancer, we will adopt the method of meta-analysis to comprehensively analyze the existing data, in order to provide evidence-based medical evidence for the relationship between CD44 gene rs13347 locus polymorphism and breast cancer genetic susceptibility.The association between CD44 gene rs13347 locus polymorphism and breast cancer has been paid attention by many scholars. Although there are many studies on the relationship between CD44 gene rs13347 locus polymorphism and breast cancer susceptibility,22.1 Moreover, it has been registered on open science framework (OSF) (Registration number: DOI 10.17605/OSF.IO/WBC7F).This protocol of systematic review and meta-analysis has been drafted under the guidance of the preferred reporting items for systematic reviews and meta-analysis protocols.2.2Since the programme does not require the recruitment of patients and the collection of personal information, it does not require the approval of the Ethics Committee.2.3(1)The subjects are those who are diagnosed as breast cancer by pathology and the control group (non-breast cancer patients). There are not any limitations on age, race and region of the patients.(2)The type of study is an observational study to study the relationship between CD44 gene rs13347 locus polymorphism and breast cancer . The language is limited to Chinese and English.(3)The distribution frequency data of alleles or genotypes are available.(4)The distribution frequency of genotypes conforms to the Hardy-Weinberg law.2.4(1)Repeatedly published research.(2)Articles in which the published literature is an abstract or review, the data of the article is incomplete or incorrect, and the complete data can not be obtained after contacting the author.(3)The study on the failure to provide detailed data on the frequency of genotypes.(4)Animal research or experimental research.2.5Take “CD44”, “gene polymorphism” and “breast cancer” as Chinese search words, and search them in Chinese database, including China National Knowledge Infrastructure, Wanfang, VIP Information Chinese Journal Service Platform, Chinese BioMedicine Literature Database. “Cluster of Differentiation 44,” “CD44,” “polymorphism,” “breast cancer,” “breast tumor,” and so on are used as English search words in the English database, including PubMed, EMBASE, Web of Science and the Cochrane Library. From the establishment of the database in March 2021, all the literature about the relationship between CD44 gene rs13347 polymorphism and breast cancer is collected. Take PubMed as an example, the retrieval strategy is shown in Table 2.6Two researchers independently complete the literature screening, exclude the studies that obviously do not meet the inclusion criteria, and further read the abstract and the full text to determine whether they meet the inclusion criteria. The data included in the literature are extracted and cross-checked. In case of disagreement, consult with the third researcher and reach a consensus. The extracted data include: the first author, the number of years of publication, the country of publication, the race of the research population, the basic characteristics of the study population , the distribution of each gene phenotype (whether obeying the law of Hardy-Weinberg equilibrium), the detection method of gene polymorphism and so on. The literature screening process is shown in Figure 2.7 including 3 columns and 8 items with a total of 9 points, and the evaluation criteria is ≥ 6 for high quality, while the cross-sectional study is evaluated with 11 standard items recommended by Agency for Healthcare Research and Quality for evaluation of cross-sectional study. 0 to 3 as low quality, 4 to 7 as medium quality, 8 to 11 as high quality.The case-control study and cohort study are evaluated by Newcastle-Ottawa Scale,2.82.8.1x2 test is first used to test whether the genotypic distribution of the control group in each study is in line with Hardy- Weinberg genetic equilibrium (P ≥ .05). Meta-analysis is carried out by using STATA.16 software, the continuous variables are expressed in the form of standard mean difference and 95% confidence interval, and the binary classification variables are expressed as odds ratio and 95% confidence interval. Heterogeneity is analyzed by Q test and I2, and the heterogeneity is evaluated according to the I2. If P > .1, I2 < 50%, the heterogeneity among the included studies is small, so the fixed effect model is used for analysis; if P < .1, I2≥ 50%, the heterogeneity between the included studies is obvious, and the s urces of heterogeneity are analyzed. Random effect model is used for analysis.Before evaluating the association between gene polymorphism and breast cancer, 2.8.2If the data of the required study are incomplete or not reported in the study, the researcher will contact the first author or other author of the study by phone or email. If the required data are not available, we will use descriptive analysis instead of meta-analysis and exclude these studies if necessary.2.8.3In order to deal with the heterogeneity between different studies, subgroup analysis will be conducted according to the population , race  and regional .2.8.4In order to test the stability of the meta-analysis results, we will use the one-by-one exclusion method to analyze the sensitivity of the results through Stata 16.0.2.8.5P < . 05, it considers to have obvious publication bias.We will use to funnel chart to qualitatively identify publication bias, and use Egger and Begg test to quantitatively evaluate publication bias. If the funnel diagram is asymmetrical and 2.8.6 The quality of all evidence will be assessed on four levels  in terms of five aspects .We will use the Grading of Recommendation Assessment, Development and Evaluation scoring method to grade the outcome indicators of evidence.3,20The incidence of breast cancer is gradually increasing worldwide. According to the World Health Organization, there will be more than 19 million confirmed cases of breast cancers in the world by 2025. The pathogenesis of breast cancer is complex, and genetic susceptibility factors are closely related to the pathogenesis of breast cancer. In recent years, research and discussion of breast cancer susceptibility genes have become the focus of scholars all over the world. Previous studies have shown that CD44 gene SNP, can be detected in 84% of breast cancer patients. Therefore, CD44 gene may be one of the high-penetrance genes that affect breast cancer susceptibility. The human CD44 gene is located on the short arm of chromosome 11 (11p13) and consists of 20 highly conserved exon and introns of different lengths. More and more studies have focused on the impact of CD44 gene ssingle-nucleotide polymorphisms on cancer risk. Among them, rs13347 polymorphism located in the 3’- untranslated Region of CD44 gene is the most studied. It affects the expression of CD44 gene by affecting the regulation of CD44 gene by hsa-miR-509–3P, and then affects the occurrence and development of breast cancer.At present, there have been many studies on the relationship between single-nucleotide polymorPhisms and susceptibility to breast cancer. However, these SNP genes, including BRCA1 and BRCA2, can only explain about 25% of the susceptibility and incidence of breast cancer. Therefore, this study will explore the relationship between CD44 gene rs13347 polymorphism and breast cancer by systematic review and meta-analysis, and provide evidence-based basis for CD44 gene polymorphism in risk assessment, early detection and prevention of breast cancer.Due to the differences in analytical methods, race and region of gene polymorphism, the relationship between CD44 gene rs13347 polymorphism and breast cancer is controversial.However, this study has some limitations: due to the limitations of language retrieval, we will only include Chinese and English literature in this study, and may ignore the research in other languages. Different race, skin color and disease and other factors may cause a certain degree of clinical heterogeneity.Data collection: Zilong Shao and Zhibin WangFunding support: Xiang JinResources: Zhibin Wang and Liwei ShaoSupervision: Zilong ShaoSoftware operating: Zhibin Wang and Liwei ShaoWriting – original draft: Zilong Shao and Zhibin WangWriting – review & editing: Zilong Shao and Xiang Jin


After swaging, the laminates with diameters of 15 mm were subjected to two different post-process annealing treatments. Structure analyses performed to evaluate the effects of thermomechanical processing were performed via scanning and transmission electron microscopies. Electric conductivity and resistivity of the laminates were experimentally measured and numerically simulated using models designed according to the real conditions. The results showed that the electric resistivity was affected by the grain size, bimodal grains’ distribution (where observed), the presence of twins, and, last but not least, dislocation density. Among the influencing factors were the area fractions of Al and Cu at the cross-sections of the of the laminated conductors, too. The results revealed that fabrication of the laminate via the technology of rotary swaging introduced more advantageous combinations of electric and mechanical properties than fabrication by conventional manufacturing techniques. The lowest specific electric resistivity of 20.6 Ωm × 10 Generally, laminates are structures consisting of more than one material , and can be fabricated in various forms . Metallic laminates, which can also be denoted as bimetallic composite materials, are popular modern industrial materials and can find their use e.g., in automotive, aerospace, and marine fields ,2. The fNot only the design of the laminate, i.e., the selection of component metals and their localization, but also the production method and selected processing temperatures non-negligibly influence the final properties. Metallic laminates can be manufactured by methods  introducing elevated temperatures, such as various types of welding and cladding ,4,5,6,7.The methods of plastic deformation are based on imposing (high) shear strain into the processed materials, which enables metallurgical bonding of the individual composite components. Generally, the higher the amount of the imposed strain, the better the bonding quality. For this reason, the methods of severe plastic deformation (SPD), especially equal channel angular pressing (ECAP) ,9,10 andThe applied processing conditions, such as the deformation ratio, stress state, and amount of imposed strain, affect the deformation behaviour of the laminate , preferential deformation mechanisms , structure modifications , and consequently also the mechanical, physical, electrical, and utility properties . For exa2O precipitates in the structure substantially reduces plasticity and durability and can result in the formation of bubbles and subsequent cracking when in contact with hydrogen  , S is the cross-sectional area of swaged laminate [m2], V1 is the voltage drop [V], I1 is the DC current supply [A], L is the measured length between the voltage sensors of the swaged laminate [m], and C is the constant for the characteristic dimension [m].Measurements of electric resistivity V1 on the electric current for the original Al and Cu laminate components. The measured values were smoothed by a linear fit for both metals. The slopes of the curves (V1/I1) determine the resistivity R of the measured metals per 1 m of length.Before measuring the electric characteristics of the laminated composite rods, the data for the original Al and Cu materials were acquired. Structure analyses of the swaged (and heat treated) laminated rods were carried out by scanning and transmission electron microscopies (SEM and TEM). The samples for SEM electron backscatter diffraction (EBSD) observations, prepared from transversal cuts, were grinded manually, polished electrolytically, and observed using a Tescan Lyra 3 XMU FEG/SEMxFIB device equipped with a Symmetry EBSD detector . The analyses were carried out with the step of 0.5 µm on samples tilted by 70° and evaluated with the help of Aztec Crystal software . Detailed analyses of substructures of the Cu lamellas from the swaged and heat-treated laminates were performed using TEM . The observations were performed at 200 kV on samples prepared using the focused ion beam (FIB) method assembled on the Tescan Lyra 3 XMU microscope. During FIB preparation, a lamella was milled with Ga ions in multiple steps to a final thickness of about 120 nm. The FIB lamella was taken from a transversal cut through a peripheral Cu lamella, and thus the TEM observations were carried out in a direction parallel to the swaging axis. The last experimental step involved Vickers microhardness measurements, which were performed using a Zwick/Roell testing device . For each indent, the load was 200 gf, and the loading time was 10 s.To supplement the results of experimental investigations, numerical simulations of the current transfer were performed for the swaged laminated rods with diameters of 20 mm, 15 mm, and 10 mm. The geometries of the swaged rods models ensued from the experimentally observed ones. In other words, the locations and deformations of the individual composite components of the modelled rods were based on the locations and deformations of the Al/Cu laminate components observed experimentally via SEM.A, B, and C, and the cross-section of a laminated rod corresponding to the real laminate swaged to the diameter of 15 mm. The model of the laminated rod consisted of three individual modelling components:-A—auxiliary components serving as the input and output of the electric current. The terminal cylindrical material volumes served to stabilize the current lines occurring by the effect of current transfer and represented the total current I = 100 A. In the numerical model, these terminal volumes were defined as conductors with negligible electric conductivity.Components -B—represented the operational part of the laminated conductor. They enabled homogeneous transformation of the computational elements in the model and provided the smooth attachment of the central part of the laminate.Components -C—Represented the significant  part of the laminate, on which evaluation of the output parameters was performed. The basic parameters were the distribution of the current density across the cross-section of the swaged laminate, and the power loss occurring due to the flowing current.Components I = 100 A. After determining the values of transferring current (input parameter) and power loss (output parameter), the calculation of the total value of electric resistance of the laminated conductor was performed via Equations (3) and (4),dP is the current loss (W), σ is the electric conductivity of the material from which the conductor is fabricated (Sm−1), J is the current density (A/m2), dV is the element of the conductor volume (m3), R is the resistance of the conductor (Ω), and I is the value of the supply current.The electromagnetic model of the laminated conductor was used to perform a harmonic electromagnetic analysis using Ansys Electronic Desktop software. A harmonic electromagnetic simulation enabled us to determine the value of power loss dP (W) when the value of the current in the conductor was known. The value of the current used in the simulation, as well as during the experiments, was To determine the final value of electric resistance of the laminated rod, the basic equation for the calculation of the total resistance of net resistances in series and parallel circuits see  was usedi. In the elements (nodes) i of the conductor, the ideal mutual connection between the laminate components was considered. The final resistance of the entire length of the conductor then consisted of the sum of resistances for the elements i, which represented the parallel combination of n resistances determined by the cross-section of the conductor, and specific electric resistivity of the relevant metallic component of the laminate. Element i of the laminate also represented 1/n portion of the total resistance of the total conductor length. For this reason, the resulting final resistance was equal to the parallel combination of resistances of the individual metallic components. The final relation applicable for the calculation of specific electric resistivity of the laminated conductor was then depicted via Equation (5),ρ is the specific electric resistivity (Ωm), A is the area (m2), Cu and Al are indices to characterize the individual component metals, and lam is the index to characterize the laminated rod.The parallel resistance parts, RAli||RCui, represented the length portion of the laminated conductor selected for the elements HT1 did not impart substantial restoration, as the structure still contained a high density of dislocations  laminated rods were observed in detail via TEM. Swaging down to the diameter of 15 mm imparted the accumulation of structural defects and substructure formation. Accumulated dislocations forming dislocation cells within the swaged laminate are depicted in ocations d. FinallHT1 laminate  , as the average grain sizes for the HT1 laminate were 4.8 µm for Cu and 3.2 µm for Al components. Compared to the swaged state, the standard deviations from the average grain sizes also increased for both the metals, which confirmed the presence of a bimodal grain size distribution  for the original Cu and Al were 36.9 µm and 64.0 µm, respectively. The average grain sizes within the swaged laminate were 3.1 µm for the Cu and 3.0 µm for the Al components. The HT1. Finally, HT2.The grain size distributions for the original CP Cu and CP Al are depicted in As evident from As regards the electric characteristics of the swaged (and heat treated) laminates, the results of the numerical simulations were evaluated at first. The basic output of the harmonic analysis was the distribution of current density across the cross-sections of the swaged laminates, which is depicted in −9 and 225.1 Ω × 10−6 for Cu, and 28.772 Ωm × 10−9 and 441.3 Ω × 10−6 for Al. During evaluations of the electric properties of the laminates, these values of the original metals were considered.The methods by which the electric characteristics of the laminates were further experimentally measured and calculated were described in V1 on the applied electric current for the swaged (and heat treated) laminated rods. Similar to the original CP metals, the data for the laminates were smoothed by linear fits. The figure thus depicts that the values of the voltage drop exhibited a linear increase with increasing electric current applied for all the examined material states. The slopes of the curves again characterized the resistances R of the laminated rods. As can be seen from the figure, the resistances of the swaged laminate and laminate heat treated via regime HT2 were comparable. However, the laminate heat treated via regime HT1 exhibited significantly increased resistance. To enable a comparison of resistances of the produced laminates, HT2 laminate. The HT1 laminate exhibited deteriorated electric conductivity when compared to both the original metals in swaged states.The assembled laminated semi-products with an original diameter of 50 mm were gradually swaged to laminated rods with a diameter of 15 mm, which not only affected the structures of the laminates, but also their electric properties. Swaging with a total reduction ratio of 2.4 resulted in deformation strengthening and significant grain refinement, pointing to the occurrence of dynamic recrystallization during processing.HT1 treatment performed at 250 °C introduced the slight growth of the grains, rather than further recrystallization. This fact was also confirmed by the grain size measurements, as the average grain sizes of both the Al and Cu components increased slightly after the HT1 treatment (compared to the swaged laminate). Nevertheless, increasing the annealing temperature to 350 °C imparted sufficient energy for the grains to exhibit the annihilation of dislocations (confirmed by TEM) and partial recrystallization, which was proven not only by the grain size analyses, but also by the presence of fine grains featuring randomized orientations  within the Al matrix and Cu lamellas of the HT2-laminated rod.Generally, the grains within the Cu lamellas were larger than the grains within the Al matrices for all the swaged and heat-treated laminated rods. The primary reason for this phenomenon was that deformation strengthening was processed differently within the metallic components, which was given by the differences in their intrinsic properties and lattice parameters (the Al matrix tended to consume the imposed shear strain more easily than Cu) . The Al HT2 laminate, especially due to the observed decrease in dislocation density, which resulted in structure softening. The structural phenomena occurring also introduced changes in the geometrical distribution of the metallic components across the cross-section of the laminated rod. As documented by the results of numerical simulations, the current density, as well as the consequent electric characteristics of the laminate, were not only affected by the area fractions of the metallic components across the cross-section of the laminate, but also by the electric conductivities of both the metallic components. The material featuring a lower electric resistivity, i.e., higher conductivity, had a higher tendency to transfer the electric current despite the fact that its cross-sectional area fraction across the transversal cut through the laminate was lower. The higher current density of the respective metallic component caused the electric current to flow primarily through that part of the laminated conductor featuring a lower value of specific electric resistivity. Moreover, from the viewpoint of the transfer of electric current through the laminated conductor, it was not important whether the lengths of the individual material components were mutually insulated, or closely connected, or whether they exhibited certain transitional resistance.The observed grain size changes were non-negligibly connected to the substructure development and changes in microhardness of the metallic components, as these phenomena were introduced by the imposed shear strain, i.e., deformation strengthening. Compared to the swaged state, microhardness decreased for the V1 measured for the commercially available electro-conductive CP Cu and CP Al components were different than those calculated for swaged CP Cu and CP Al rods (linearly increasing trend was considered). In other words, the V1 value at the maximum current of 100 A was V1= 44 mV for Al and V1= 22 mV for Cu  resulted in increased electric resistivity compared to the swaged material state. On the contrary, heat treatment at the higher temperature (HT2) imparted the annihilation of dislocations, the development of twins, and a relatively large fraction of recrystallized grains featuring randomized orientations. These phenomena again resulted in decreased electric resistivity—its value for the HT2 laminate was comparable to that of the swaged laminate. In summary, structural phenomena, such as deformation twins, can decrease electric conductivity . However, their presence in deformed laminates is not as significant from the viewpoint of increasing electric resistivity. On the other hand, heterogeneity in the orientations of (sub)grains can be a much more substantial factor influencing the electric conductivity of the laminate.Partial structure restoration, i.e., the presence of small, recrystallized grains with randomized preferential orientations within the structure (primarily the Al matrix), imparted an increase in the electric resistivity. In other words, partial reorientations of subgrains, i.e., grains defined by low-angle grain boundaries newly developing within the original grains , introduHT1, and 350 °C = HT2). The main acquired results were the following:Swaging to the diameter of 15 mm imparted favourable electric characteristics and an increase in microhardness up to 115 HV for the Cu components of the laminate.HT1 material state—the occurrence of relatively small, restored grains with randomized preferential orientations was the main reason for the observed deterioration of electric conductivity (specific electric resistivity of approx. 34 × 10−9 Ωm compared to approximately 23.5 × 10−9 Ωm for the swaged state).HT2 material state—the electric conductivity improved to a level comparable with the swaged state (approximately 22.7 × 10−9 Ωm); in addition, the higher annealing temperature caused bimodal grain size distribution and the development of annealing twins.A favourable effect of rotary swaging on the electric conductivity was also observed for the original Al and Cu —this phenomenon was related to substructure development  imparted by swaging.This paper aimed to characterize the electric properties and structural features of Al/Cu-laminated rods, which were successfully prepared via combinations of room-temperature rotary swaging and post-process heat treatments. The assembled composites 50 mm in diameter were progressively swaged down to laminated rods with a diameter of 15 mm, and subsequently subjected to two heat treatment regimes , the Al/Cu laminate is supposed to also be suitable for alternate current transfer; the detailed investigation of the behaviour of the Al/Cu laminate during alternate current transfer is the primary focus of our ongoing research.


Next, after 7 days of sample maturation, compressive and flexural strength tests were carried out and continued after 28 and 90 days of the maturing of the mortars. The best test results were obtained for mortars with the addition of 1% aluminum nanoxide, the compressive strength of which increased by about 20% compared to the reference mortars. The water absorption and rising capillary tests as well as SEM observations were also performed. Another aim of the article is the analysis of the fracture morphology of nano-Al2O3 modified mortars. It is assumed that a change of the microstructure of the hardened cement paste affects not only the properties of the modified mortars but also the roughness of the fractures formed as a result of the destruction of the surface. Roughness analysis was performed with methods and tools relevant to fractal geometry. The fractographic analysis showed a significant influence of the modifier in the form of nano-Al2O3 on the values of fractal dimensions. The lowest values of the fractal dimension D and the fractal dimension of the RPD roughness profile of the fracture surface profile lines were obtained for nano-Al2O3 modified mortars. The conducted research proved the fractal dimension to be a parameter extremely sensitive to modifications of mortar composition as well as changes related to the maturation time.This article presents the effect of aluminum nanoxide on the physical, strength and structural properties of cement mortars. The mortars were made with a water to binder ratio of 0.5 and a binder to sand ratio of 1:3; and 1%, 2%, 3% and 4% of aluminum nanoxide, respectively, were used by cement weight. First, the consistency of nano-Al Curre2 ,15,16,172 [2 ,19,20. M2 [2 . Recent chnology .2 portlandite and the formation of an additional amount of C–A–S–H phase [2O3 is higher than that of concrete containing the same amount of nano-SiO2. The chloride binding capacity can be improved by introducing nano-Al2O3 into cement paste. The bound chloride content is increased by 37.2% at 0.05 mol/L NaCl solution with 5.0% nano-Al2O3 [2O3 on the mechanical properties was generally attributed to its physical action (filler effect), which led to accelerated hydration in the early period [3A) by increasing the second peak of the heat flow curve, indicating possible dissolution of nano-aluminum particles in the pore solution [2O3 (γ phase) quickly dissolves on contact with an aqueous solution at pH = 11, and the actual aluminum concentration increases rapidly until it reaches its maximum value . It is commonly known that the pH of a pore solution in a cementitious binder can reach a very high level within minutes after being mixed with water. The high alkalinity of the pore solution (pH > 12.5) would have a significant effect on the solubility of nano-aluminum oxide, chemically influencing the aluminate reaction during the early phase of hydration.Aluminum nanoxide fills the voids between cement grains, as a result of which capillary pores are closed ,23,24. W–H phase  and also–H phase ,27,28. Bno-Al2O3 . The effy period ,30. Somey period  or only y period , possiblsolution . As an asolution  found th2O3 modified mortars. Fracture morphology analyses provide a quantitative description of the structure of materials, including cementitious matrix materials. Importantly, they provide information on the image of damage which can be described in a simple way by means of fractal geometry [Following the few published experimental works and their original research, the authors of this study focused on the analysis of the morphology of fractures of nano-Algeometry ,35,36. Igeometry , may alsgeometry ,40,41,42−Cement: CEM I 42.5 R. The physical and mechanical properties of Portland cement used following the requirements of PN-EN 197-1: 2012 .−Aggregate: Quartz sand, grain size up to 2 mm. Sands used followed the requirements of PN-EN 12620:2004. Producer: ZEK STRZEGOCICE II .−Superplasticizer: Masterglenium 115—superplasticizer based on polycarboxyl ethers.−Aluminum nanoxide: nanoparticles whose grain size declared by the manufacturer is 40 nm To determine the size of nanoadditive particle, a NanoPlus HD wet dispersion system was used to measure particle sizes from 0.1 nm to 12.300 nm (conforming to ISO13321 standard for particle size). The dispersing liquid was water. A unimodal distribution of the curve of the normalized intensity distribution was obtained, and the repeatability of the results for three samples confirmed the homogeneity of this material. The occurrence of grains with diameters ranging from about 250 nm to 5000 nm was found. The mean chord of three measurements was 856.4 nm, with 90% occurrence of grains of the diameter below 2072.4 nm. The reason why we checked the particle size distribution was because of the results of preliminary studies and SEM observations.−Testing the consistency of mortars employing the spreading table method after PN-EN 1015-3:2000 . The mea−3 using a testing machine. Compressive strength was determined on the halves of the three samples that remained after the mortar bending test.Flexural and compressive strength of testing mortars after 7, 28 and 90 days of mortar curing after PN-EN 1015-11:2001 . The det−Testing water absorption resulting from the capillary rise after 28 days of mortar curing after PN-EN 1015-18:2002 . During −Absorption testing of mortars after 28 days of mortar curing after PN-B-04500:1985 . During −Analysis of the morphology of the fractured  surfaces of the mortar sample fractures was performed using a Taylor Hobson Talysurf CLI 1000 laser profilometer  with software and the “FRAKTAL_Dimension2D” program  . The surThe scope of the experimental methods included the following:The mixtures were divided into five groups on the basis of the variable amount of introduced aluminum nanoxide . The amount of nanoparticles was added based on the weight of the cement. Alumina nanoparticles in the form of powder were added to the mixing water in order to better disperse the nanoparticles, and they were dispersed using a Sonopuls HD 3200 sonicator  .Masterglenium 115 superplasticizer was added in proportion to the weight of the binder, the amount of which increased proportionally to the amount of aluminum nanoxide added. It acted as a dispersant. A constant water to binder ratio of 0.5 was adopted. Designations and compositions of individual mixtures are presented in 2O3 modified mortars deteriorated with the increase in the amount of introduced nano-alumina. The water demand of the binder increased with the increase in the amount of aluminum nanoxide. In order to maintain a solid consistency, a superplasticizer was used, which, in addition to the function of a dispersing agent, also acted as a liquefier. Analysis of the results of all the tested mortars indicated that they are comparable. The spread of the tested mixes oscillated within the range of 14.5–16 cm. All the tested mixtures were workable.The consistency of the mixture containing aluminum nanoxide introduced as a partial cement replacement depends on the amount of this additive. The aim of the research was to obtain a constant consistency with a water to binder ratio. Aluminum nanoxide impacted the consistency of the tested mortars. The workability of nano-AlThe consistency of all mortars is shown in In order to evaluate the influence of aluminum nanoxide on the strength properties of cement mortars, three samples of each series with the dimensions of 40 mm × 40 mm × 160 mm were made and cured at the temperature of 20 °C ± 2 °C and at the relative humidity of 65% ± 5%. The flexural strength and compressive strength of the mortars were determined after 7, 28 and 90 days of curing. The tests were carried out on an automatic press for measuring the strength of cement samples after PN-EN 196-1. The obtained results are shown in 2 during the hydration of Portland cement, especially in the initial period associated with the high reactivity of nano-Al2O3 particles. The presence of Al2O3 nanoparticles in the cementing system not only improves the particle packing density but also consumes portlandite (Ca(OH)2). The portlandite consumption is caused by the pozzolanic reaction, forming additional C–S–(A)–H gel that fills the capillaries and reduces the pore structure of concrete and consequently, increases its strength. Nano Al2O3 particles act as nuclei for the cement paste further accelerating the cement hydration reactions. Due to their high reactivity, and as a nano-filler material, nano particles lead to the densification of the cement microstructure and, hence, reduced porosity and enhanced strength [2O3 modified mortars was demonstrated by the mortar with the addition of 1% alumina nanoparticles. Compared with the reference mortar MNA-0, MNA-1 mortar showed an increase in compressive strength after 7 days by about 20%. With the increase of the addition of aluminum nanoxide, the compressive strength of mortars decreased, but it was still higher than that of reference mortars. This was most likely caused by the uneven distribution of aluminum nanoxide in the mortar.The analysis of the obtained flexural strength results indicated that the results for all the series of the tested mortars are comparable after 7, 28 and 90 days of curing of the tested mortars. It should be noted that as the amount of introduced alumina nanoparticles increases, the flexural strength decreases. Significant differences in the results can be seen in the compressive strength test of the mortars. Aluminum nanoxide had a positive effect on the early compressive strength of mortars, but also on the compressive strength of mortars after 28 and 90 days of curing compared to the reference mortar samples. The increase in compressive strength results from the rapid consumption of Ca(OH)strength ,51,52. T2O3 and the mortars’ age  were performed. An F Snedecor (Fisher) qualitative analysis was done in order to demonstrate the impact of the adopted variables on the property tested. The analysis of the results of tests of both flexural strength (test statistic F = 14.27) and compressive strength of mortars (test statistic F = 54.93) yielded critical levels of significance p close to 0, which proves the statistically significant effects of the adopted independent variables on these output values. At the same time the F test is a test of the equality of mean values of flexural/compressive strengths, and its results confirmed the statistical differentiation of the mean values in particular series depending on the adopted variables. The scatter of the results of flexural and compressive strengths in particular mortar series is shown graphically in Additional in-depth statistical analyses with STATISTICA  of the results of tests on mortars’ flexural and compressive strengths, taking into account the proportion of Al2O3 in the mortar. The homogeneity of variance was checked with the Brown–Forsythe test. For both parameters the critical level of significance p, which was 0.97 for flexural strength and 0.53 for compressive strength, indicated variance homogeneity. The fact that homogeneity of variance was achieved confirms adequate dispersion of nano-Al2O3W in the mortar.To detect any potential impact of other variables on the parameters tested, the homogeneity of variance was checked. The factors that might make the scatter wider included a technological issue of adequate dispersion of nano-Al2O3 proportion and mortar age as independent variables and flexural strength rf or compressive strength cf of mortars as a dependent variable, the following dependences, (1) and (2), were obtained:T is the age of mortar, x is the proportion of nano-Al2O3 and N is the number of cases.Through the application of the multiple regression method together with the adoption of nano-Alp close to 0). For model (2) of multiple regression, only the insignificance of the term for the linear effect of the variable of nano-Al2O3 proportion was shown. For model (1), based on the results of multiple regression analysis, it was found that the contribution of the variable of mortar age in the prediction of flexural strength was about three times greater than the contribution of nano-Al2O3 (regression standardized coefficients ratio of 0.79/0.26).The statistical significance of correlation was confirmed (T), nano-Al2O3 proportion (x)), also in the second power, was employed. After the elimination of coefficients, statistically insignificant functional dependences were reached:Because of low values of correlation coefficients in the case of multiple regression, for the search for dependencies, a non-linear estimation method adopting the output model variables (mortar age (R) was observed. The surface diagrams thereof are shown in The proposed functions (3) and (4) were valid only in the experiment, i.e., for mortars aged seven to ninety days. The maximal and minimal error of +3.0% and −3.3%, respectively, of the estimation of mean value expected on the basis of Equation (3) compared with the observed  value was obtained. The mean absolute error of the estimation of this value was 1.7%. In the case of compressive strength and the use of Equation (4), the maximal and minimal error was +6.0 and −3.7%, respectively, and the mean absolute error of the estimation of mean compressive strength was 1.8%. Better fitting of the results of experimental studies to the model  of the impact of the mortar composition modifier used on the morphology of the fracture surface formed as a result of cracking was carried out and described by selected fractographic parameters. The obtained significance values D and on the value of the fractal dimension of the RPD roughness profile according to a significance level of 0.05. At the same time, a differentiated effect of introducing nano-Al2O3 into the composition of mortars was shown on the second fractographic parameter, i.e., total height of Pt profile and total height of RPPt roughness profile. The results of the analysis are presented in The analysis showed a statistically significant effect of aluminum nanoxide on the value of the fractal dimension Based on the results of fractal studies, the influence of the applied modifier on the morphology of the mortar fracture surface formed as a result of destruction, characterized by profile lines separated out from these surfaces, was demonstrated .D of profile lines of fracture surfaces were obtained for mortars modified with nano-Al2O3. The lower fractal dimension D indicates a reduction in the roughness on the fracture surface and, at the same time, a more homogeneous structure of the hardened cementitious composites.  were also mortars with higher compressive strength. The lowest values of fractal roughness profile of RPD were also obtained for mortars modified with alumina nanoparticles (2O3 products and with Ca(OH)2. This resulted in a greater homogeneity of the microstructure of the hardened mortar and a reduction of the fracture surface roughness. The values of both fractographic parameters  for mortars modified with aluminum nanoxide were about 10% lower than the values of the same fractographic parameters for unmodified mortars.Mortars for which flatter fracture surfaces were obtained , with a significance level of 0.05 adopted, showed changes in the microstructure of the hardened cement paste for each series of mortars modified with aluminum nanoxide. The fractal dimension of the RPD roughness profile proved to be the most sensitive to changes. In this case, all the values of the significance level limit p were close to 0, which proves the influence of mortar age on the value of the fractal dimension of the RPD roughness profile.An in-depth statistical analysis  of the eRPD roughness profile in the first periods of study (after 7 days of curing)  is closely related to the microstructure of the grout. Modification of the microstructure with aluminum nanoxide resulted in low values of the fractal dimension of the  curing) .2 crystals, which at the same time increased the dimension of the fractal roughness profile. The further process of cement hydration and building a structure based on dicalcium silicates  increased the strength and reduced the fractal dimension of the RPD roughness profile  profile . The dim2O3 into the mortar composition on the value of the total height of the Pt profile and the value of the total height of the RPPt roughness profile  to describe the fracture surface morphology than the traditionally used fractographic parameters (Pt and RPPt).The conducted analyses confirmed greater usefulness of using fractal parameters . The F Snedecor–Fisher test indicated a statistically significant impact of the variables (proportion of nanopowder and mortar age) on the roughness profile fractal dimension RPD, the critical level of significance p close to 0 (test statistic F = 53.44). Moreover, the homogeneity of variance was confirmed, and the critical level of significance level was achieved p = 0.06.The statistical analysis of the results of roughness profile fractal dimension RPD in the form of functional dependencies  on the roughness profile fractal dimension ndencies .2O3 proportion as independent variables as well as for the adopted significance level, a dependence for the prediction of roughness profile fractal dimension RPD was obtained:T is the age of mortar, x is the nano-Al2O3 proportion and N is the number of cases.Employing the multiple regression method, adopting mortar age and nano-Al2O3 proportion (x)) to the prediction of the dependent variable (RPD) was compared. In this case, the nano-Al2O3 proportion was an over 5.6 times greater predictor of the roughness profile fractal dimension than mortar age. As follows from model (5), both mortar age and nano-Al2O3 proportion decreased the roughness profile fractal dimension. A lower profile roughness indicated a more homogeneous microstructure of hardened cement paste and better sand grains to paste binding.Dependence (5) was obtained on the basis of 300 actual results of roughness profile fractal dimension determined following the profile lines separated out from the mortar fracture surfaces. The resulting correlation may be classified as good fitting of the results of actual physical experiments to the expected ones. The relative contribution of each of the independent variables (mortar age (T), nano-AlDue to the character of the fracture surface of materials of cementitious matrix, the values of fractal dimension obtained for a single surface fracture were widely scattered. However, as shown in , and as 2O3 increases, so does the water demand for the binder. In order to prevent this, an admixture based on polycarboxyates was used, which, in addition to the function of a dispersing agent, acted as liquefier.The addition of aluminum nanoxide as a partial replacement for cement affects the consistency of mortars. As the content of nano-Al2O3 is demonstrated by the mortar with the addition of 1% alumina nanoparticles. Compared with the reference mortar (MNA-0 series), the MNA-1 series mortar shows an increase in compressive strength after 7 days by about 20%. With the increase of the addition of aluminum nanoxide, the compressive strength of the mortars decreases, but it is still higher than the compressive strength of the reference mortars. The decrease in compressive strength is caused by the formation of nano-Al2O3 agglomerates in the structure of mortars. This phenomenon results from the high specific surface area of the alumina nanoparticles.Aluminum nanoxide has a positive effect on the early compressive strength of mortars but also on the compressive strength of mortars after 28 and 90 days of curing compared with the reference mortar samples. The highest compressive strength of mortars modified with nano-Al2O3 proportion and mortar age) on the output values . The multiple regression method employed additionally enabled a description of the dependencies in the form of regression models (1) and (2). The results revealed that in model (1) the impact of the variable of mortar age on mortar flexural strength prediction is about three times greater than that of the variable of nano-Al2O3 proportion. In model (2) the impact of nano-Al2O3 proportion turned out to be negligible.The results of the qualitative analysis (F Snedecer–Fisher test) proved a statistically significant impact of independent variables  and (4), obtained by means of a non-linear estimation method, yielded better fitting of the results of empirical tests to the expected ones and indicated the significance of the impact of the variable nano-Al2O3 is lower by about 15%. The lowest capillary adsorption coefficient was demonstrated by the series of MNA-1 mortar with 1% content of aluminum nanoxide. Compared with the reference mortar, the capillary adsorption coefficient of MNA-1 mortar is lower by 21%. The lower capillarity of mortars modified with nano-Al2O3 is mainly due to the filling of capillary pores with aluminum nanoxide particles.Alumina nanoparticles have a positive effect on the capillary adsorption coefficient. Compared with the reference mortar, the capillarity of mortars modified with nano-AlThe results of the mortar absorbability tests showed a minor effect of the addition of alumina nanoparticles on the absorbability of the tested cement mortars. All the results are comparable and oscillate within 8.6%.D and fractal dimension of RPD roughness profile. The lowest values of fractal dimension D of profile lines of fracture surfaces were obtained for mortars modified with nano-Al2O3. Smaller fractal dimension D proves the reduction of unevenness on the fracture surface and, at the same time, a more homogeneous structure of the hardened cementitious composites. Mortars for which flatter fracture surfaces were obtained were also mortars with higher compressive strength. The fractographic parameters traditionally used to describe roughness were also found to be insensitive to changes in mortar structure. The authors suggest that the fractal dimension of the profile line should be determined on the basis of the roughness profile analysis. This approach eliminates distortions resulting from profile line analysis that includes the waviness profile. This is confirmed by analyses of the change in the fractal dimension of the roughness profile during curing.Fractographic analysis showed a significant effect of the modifier in the form of alumina nanoparticles on the value of fractal dimension 2O3 proportion as variables and for the adopted significance level of 0.05, dependence (5) was obtained that enables roughness profile fractal dimension RPD to be predicted. On the basis of model (5), it was stated that both mortar age and nano-Al2O3 proportion decrease the roughness profile fractal dimension. Lower profile roughness manifests a more homogeneous microstructure of hardened cement mortar and better sand grains to cement paste binding, which also corresponds to a higher flexural and compressive strengths of these mortars.Based on the results of multiple regression analysis performed in the format of the roughness profile fractal dimension, adopting the mortar age and nano-AlBased on the research, the following conclusions were drawn:


In addition, a hypothesis has been proposed that regions of unbound polyallylamine are responsible for the buffering properties of polyelectrolyte microcapsules. This hypothesis is confirmed by the fact that incubation of microcapsules in 0.5 M NaCl increases the amount of unbound polyallylamine, which leads to an increase in the buffer capacity of microcapsules at alkaline pH values higher than the buffer capacity of capsules in an aqueous solution.Polyelectrolyte microcapsules, which are obtained by the method of alternate adsorption of oppositely charged polyelectrolytes onto colloidal particles of micron size, are widely used in science and industry. Nevertheless, the properties of microcapsules are still poorly understood. In particular, there is no information in the literature on the buffer capacity. However, information on the presence of a buffer capacity and an understanding of its mechanisms can both simplify the use of microcapsules and expand the scope of their application. In this regard, the buffer capacity of various types of microcapsules was studied. It was found that polyelectrolyte microcapsules consisting of polyallylamine, and polystyrene sulfonate have a buffer capacity. In addition, in an acidic medium, the buffer capacity of microcapsules containing BSA is significantly greater than that of microcapsules without protein. This is due to the fact that BSA contributes to the buffering of microcapsules. Differences in the behaviour of the buffer capacity of microcapsules with the composition (PAH/PSS) Polyelectrolytes (PE) are polymers whose monomers have groups capable of ionization in solution. This electrostatic property affects many of the macromolecular characteristics of PE such as viscosity, chain shape, and energy transfer parameters. These features of polyelectrolytes make it possible to use them as destabilizers of colloidal systems and initiators of flocculation in oil production and surface water treatment. In addition, they are frequently used as thickeners, emulsifiers, conditioners, clarifiers and even flow resistance reducers in medicine, food, textile, and other industries . One of The buffer capacity (BC) of a solution is the ability of a solution to maintain a constant pH value when an acid or alkali is added. High buffering capacity is typical for weak polyelectrolytes, which have a dissociation constant (pKa or pKb) in the pH range from ~2 to ~10. They are characterized by a wide range of buffer capacities because these PEs change the degree of their (de) protonation and charge density when the pH of the solution changes. Thus, the high buffering capacity of the polyelectrolyte can be used to create the “proton sponge” effect  or stimuThe study of the buffer properties of polyelectrolyte complexes (PC) is a logical continuation of this direction. In particular, it has been shown ,7,8 thatThe buffer capacity of the polyelectrolyte complex mainly depends on the buffer capacity of the weak polyelectrolyte in the PC composition . PolyeleOne of the examples of polyelectrolyte supramolecular systems are polyelectrolyte microcapsules (PMC). PMC are spherical containers, which are obtained by the method of alternate adsorption of oppositely charged polyelectrolytes onto colloidal particles of micron size. Currently, research is underway to create targeted delivery systems, diagnostic and theranostic systems based on polyelectrolyte microcapsules ,17,18,19Thus, the purpose of our work is to discover and study the buffer capacity behaviour of different types of polyelectrolyte microcapsules at the pH range from 4 to 9.Polyelectrolytes polystyrenesulfonate sodium (PSS) and polyallylamine hydrochloride (PAH) with a molecular mass of 70 kDa, bovine serum albumin (BSA), Ethylenediaminetetraacetic acid disodium salt dihydrate (EDTA) purchased in Sigma , sodium chloride, ammonium sulfate, sodium carbonate, calcium chloride from “Reahim”.2CO3, the 0.33 M CaCl2 was added (which contained 3 mg/mL of BSA if it was necessary). The stirring time was 30 s. The suspension was maintained until complete precipitation of the formed particles. The process of “ripening” of microspherolites was controlled with the help of a light microscope. Then, the supernatant was decanted, the precipitate was washed with water and used to prepare PMC. The microparticles were obtained with an average diameter of 4.5 ± 1 μm.At stirring of 0.33 M Na3 microspherulites, followed by dissolution of CaCO3. At the moment of dissolution of CaCO3 core the inner space of PMC is filled by interpolyelectrolyte complex [3 microspherulites surface was carried out in polyelectrolytes solutions (concentration 2 mg/mL + 0.5 M NaCl). After each adsorption the CaCO3 particles with adsorbed polyelectrolytes were triple washed with a 0.5 M NaCl solution, which was necessary to remove unabsorbed polymer molecules. The particles were separated from the supernatant by centrifugation. After applying the required number of layers, the carbonate kernels were dissolved in a 0.2 M EDTA solution for 12 h. The resulting capsules were washed three times with water to remove core decay products. In the case of the PMC with an encapsulated BSA, we used a protein filled CaCO3 core which is dissolved at the final stage of preparation. The microcapsules were obtained with an average diameter of 4.5 ± 1 μm. The size and surface charge of microcapsules was measured using the dynamic light scattering method on a Zetasizer nano ZS device . The surface charge of PMC with interpolyelectrolyte complex of the following composition: (PAH/PSS)3—+23 ± 2.1 mV; (PSS/PAH)3—+22 ± 3.2 mV. The surface charge of PMC with protein of the following composition: (PAH/PSS)3–BSA—+23 ± 2.1 mV; (PSS/PAH)3–BSA—+21 ± 1.8 mV.The “BSA-free” type of polyelectrolyte microcapsules was obtained by layer-by-layer adsorbing the negatively or positively charged polyelectrolytes onto CaCO complex . Layer-b3 (6.6 × 109 microcapsules in 8 mL of water) was titrated with acid or base solutions in the pH range from 4 to 9. Titration was carried out by manual measurement. The acid or alkali (with a concentration of 0.001 M or 0.005 M) was added to the solution to change the pH of a solution by 0.02 or more. Buffering capacity was calculated from Equation (1) after estimating the slope of the titration curves at each point by the variation of the pH between previous and subsequent injections [A suspension of microcapsules (PSS/PAH)jections :(1)BC=nN3 (6.6 × 109 microcapsules in 8 mL of water) was titrated with acid or alkali solutions in the pH range from 4 to 9 to reveal the presence of a buffer capacity of polyelectrolyte microcapsules. The experimental results are shown in A suspension of microcapsules (PSS/PAH)The figure shows that microcapsules have a buffer capacity (orange curve) that differs from the buffer capacity of water (blue curve).3, (PAH/PSS)3, (PSS/PAH)3–BSA and (PAH/PSS)3–BSA. Since PMCs are complex supramolecular systems, we cannot compare their buffer capacities directly in numerical values. In this regard, we normalized the values of the buffer capacities of microcapsules, where the value of the buffer capacity at pH 7 is 100%. The results of this study are shown in The next stage of the study was to compare the behaviour of the buffer capacity of different types of PMC. The capacity of capsules of the following composition was investigated: (PSS/PAH)3 have a higher buffering capacity than (PAH/PSS)3 and it increases in pH range from 6 to 9. The behaviour of buffer capacity of BSA-containing microcapsules in an acidic medium is higher (by about an order of magnitude) than the capacity of the protein-free capsules (At ph 4 the buffer capacity of (PSS/PAH)3 without BSA is 0.535332 mmol/L and with BSA is 2.682547 mmol/L). This effect is explained by the fact that in an acidic medium BSA has a high buffering capacity [3–BSA)  B is relaThe next step in our study was to determine the causes of the buffer capacity of microcapsules. We hypothesized that the main contribution to the buffer capacity of the protein-free PMC is made by the regions of free PAH since the microcapsule is a supramolecular system, which consists of both interpolyelectrolyte complexes (PAH and PSS) and unbound fragments of polyelectrolyte chains. To confirm this hypothesis, we studied the behaviour of the buffer capacities of microcapsules in a 0.5 M sodium chloride solution. The results of this study are shown in The figure shows that the buffer capacity of microcapsules in salt increases in an alkaline medium. This confirms the hypothesis that the contribution to the buffer capacity is made by unbound PAH regions , the num3 and (PSS/PAH)3 in salt. The data are presented in This hypothesis is also confirmed by comparing the curves of the buffer capacity of microcapsules with the composition of microcapsules (PAH/PSS)The figure shows that the buffer capacity of microcapsules with the upper layer of PAH in the alkaline pH range is higher, which is explained by the larger amount of unbonded region of PAH.3 and (PSS/PAH)3 were found. In addition, we put forward the hypothesis of the presence of a buffer capacity of PMC, which consists of the fact that the regions of unbound weak PAH polyelectrolyte, which are contained in microcapsules, are responsible for the buffer properties of the capsules. To confirm this, we titrated PMC in a 0.5 M solution of sodium chloride, the presence of which leads to an increase in the amount of unpaired PAH. The results of this experiment showed that the buffer capacity of microcapsules in salt was significantly higher than their buffer capacity in water, which confirms our hypothesis.We titrated a suspension of polyelectrolyte microcapsules (PMC) consisting of polyalliamine (PAH) and polystyrene sulfonate (PSS) with acid and alkali solutions in the pH range from 4 to 9 to discover the buffer capacity of various types of microcapsules. It was found that microcapsules have a buffer capacity that differs from the buffer capacity of water and gradually increases from pH 5.5 to pH 9. A comparison of the buffer capacities of protein-containing and protein-free microcapsules showed that the buffer capacity of microcapsules with BSA is much higher in acidic pH values, which is explained by the significant contribution of protein to the total buffer capacity of such microcapsules in this range. Furthermore, differences in the behaviour of the buffer capacity of microcapsules with the composition (PAH/PSS)


Deferasirox is an orally active, lipophilic iron chelating drug used on thousands of patients worldwide for the treatment of transfusional iron overload. The essential transition metals iron and copper are the primary catalysts of reactive oxygen species and oxidative damage in biological systems. The redox effects of deferasirox and its metal complexes with iron, copper and other metals are of pharmacological, toxicological, biological and physiological importance. Several molecular model systems of oxidative damage caused by iron and copper catalysis including the oxidation of ascorbic acid, the peroxidation of linoleic acid micelles and the oxidation of dihydropyridine have been investigated in the presence of deferasirox using UV-visible and NMR spectroscopy. Deferasirox has shown antioxidant activity in all three model systems, causing substantial reduction in the rate of oxidation and oxidative damage. Deferasirox showed the greatest antioxidant activity in the oxidation of ascorbic acid with the participation of iron ions and reduced the reaction rate by about a 100 times. Overall, deferasirox appears to have lower affinity for copper in comparison to iron. Comparative studies of the antioxidant activity of deferasirox and the hydrophilic oral iron chelating drug deferiprone in the peroxidation of linoleic acid micelles showed lower efficiency of deferasirox in comparison to deferiprone. There are hundreds of thousands of iron overloaded patients belonging to different categories of inherited and other diseases, who receive regular red blood cell transfusions for the treatment of their refractory anemia ,2,3. IroThere are currently three regulatory approved iron chelating drugs which are used daily for the treatment of transfusional iron overload, namely deferoxamine, deferiprone (L1) and deferasirox (DFRA) ,6,7,8,12Investigations on the affinity and other interactions of the chelating drugs with essential and redox active metal ions are crucial for determining their therapeutic activity and toxicity potential ,14,15. OThe molecular interactions with other metal ions in addition to iron and copper, such as zinc, and with nutrients such as ascorbic acid (Asc) and also many other natural or xenobiotic molecules, are also expected to interfere with the therapeutic and toxicity potential of iron chelating drugs as well as other drugs ,20,21,22The study of the pro-oxidant/antioxidant effects of the iron chelating drugs and their iron and copper complexes is important for pharmacological/toxicological parameters affecting their mode of action and possibly their efficacy in vivo. However, the determination of the antioxidant potential of chelating drugs is also of major pharmacological interest because of possible therapeutic applications in many diseases associated with oxidative stress toxicity such as cancer, neurodegenerative, cardiac, liver, renal and other diseases ,26,27,28In this work the pro-oxidant/antioxidant effects of DFRA and its iron and copper complexes have been investigated using several molecular models of oxidative damage of linoleic acid (LA), Asc and dihydropyridine (DHP). In some of the studies L1 and Asc were used for comparison.1H-NMR spectroscopy.Linoleic acid peroxidation is widely studied in different model systems, including liposomes , but in 2+ ions has stoichiometry 1:1, and the stoichiometry of DFRA complex with Fe3+ ions 2:1. In the present studies we have tried to answer the question whether these complexes are redox active or not. For this purpose, the transition metal-induced oxidation of molecular model systems, namely LA, an unsaturated lipid, Asc and DHP as analogs of the nicotinamide adenine dinucleotide (NADH) molecule  are formed, which, in turn, are capable of conversion to other types of ROS, including the peroxyl radical and superoxide anion. The next stage of these reaction processes is “initiation”, in which the LA radical and the LA peroxyl radical are formed (3) and (4) as follows:In these reaction processes, OH radicals  and (6) as follows:At the “termination stage”, various LA dimers and polymers are formed (7)–(9) as follows:1H-NMR spectra of the initial LA in the presence of ferrous sulfate (FeSO4) and after 24 h in the absence and in the presence of DFRA. It can be seen that after 24 h, the total signal intensity of LA protons was reduced significantly. In addition, the lines at 2.7 and 2.09 ppm, corresponding to protons near the double bonds (1 and 2), disappeared. All of the above, together with the fact that an insoluble precipitate was formed during the reaction, indicates the complete consumption of LA in the solution and the formation of polymers. In the presence of DFRA, 24 h after mixing, the overall signal level was also reduced, indicating the formation of polymers, but the signals corresponding to protons near double bonds did not completely disappear. This observation suggests that there is a decrease of the initiation rate of LA oxidation in the presence of DFRA.It is also widely known that LA forms micellar solutions in an aqueous environment . In thisIt is known that the reaction of LA with OH radical starts with hydrogen atom abstraction from position 1 see  31], an, an31], This molecular model of oxidative damage monitoring using LA peroxidation has been previously used for studying the antioxidant activity of the iron chelating drug L1 in the presence of copper ions . SimilarAs can be shown in 3 protons in LA, are shown in CH3(t) is the integral intensity of the signal from CH3-groups of LA, which corresponds to the concentration of LA. The integral intensity of the initial signal of the signal from CH3-groups at 0.9 ppm (ICH3(0)) was normalized to 100. Intensity is given in arbitrary units (a.u.).The kinetics of the formation of polymeric products of LA during the oxidation reaction with ferrous ions, which are calculated from the changes in the signal intensity of CHAs can be shown in The experimental points in The results presented in An additional molecular model system for studying the antioxidant activity of DFRA was the oxidation of DHP. The reactions involving DHP are often used as models of radical processes of electron and proton transfer in living systems with the participation of NADH ,55. Dihy3OD producing ●CD2OD C-centered radical [The formation of radicals for the NMR studies was initiated by the Fenton reaction using both iron and copper as catalysts and under similar conditions reported in previous studies ,56. Sinc radical . As a re radical . The mai1H-NMR experiments, which were performed in the presence of iron and copper ions. Differences were observed in the 1H-NMR spectra of different reaction mixtures. 1H-NMR spectra of pure DHP, as well as reaction mixture of DHP with Fe3+ ions in the presence and absence of DFRA, 15 h after the initiation of the reaction.The antioxidant activity of DFRA in the molecular model of the oxidation reaction of DHP was studied in a series of It appears from The results in The experimental findings of this study have several important pharmacological, biological and physiological implications, especially for understanding the influence of DFRA on various redox systems. Deferasirox manifests its antioxidant activity in all studied model systems, including oxidation of Asc, peroxidation of LA micelles, and oxidation of DHP, with reduction in the rate of oxidation by up to several tens of times. Comparative analysis of the antioxidant activity of DFRA and L1 in lipid peroxidation showed a lower efficiency of DFRA in comparison to L1. The significance of these processes is underlined below from the different experiments carried out within this study.3+ and Cu2+, which decompose to form Fe2+ or Cu+, and the ascorbate radical (11) and (12) [Taking into account that in living systems copper and iron ions are mainly in bound forms, the study of the interaction of chelating drugs with natural complexants is an important task for elucidating the mechanism of drug action. One of the main natural antioxidant with chelating properties is Asc ,43,45,58and (12) ,60:Fe3+ Subsequently, ascorbate radicals are also capable of oxidizing, forming dehydroascorbate, which, in turn, undergoes the stages of hydration and decarboxylation, forming secondary reaction products ,62. In aThe study of Asc oxidation was carried out in ethanol since DFRA and its complexes with iron and copper ions have much lower solubility in water. Based on Another, but no less important, effect of the antioxidant activity of chelators is the ability to inhibit lipid peroxidation. The study of this reaction is part of the solution to a wider problem, namely, the study of ferroptosis-programmed cell death. This mechanism is based on the oxidation of the cell membrane by ROS, formed in redox reactions with the participation of iron ions ,65. At tAt the moment, there are many different methods for studying lipid peroxidation, the vast majority of which are based on the detection of oxidation by-products of trichloroacetic and 2-thiobarbituric acids ,34,67,68In the present study it was shown that DFRA inhibits LA peroxidation in micelles; however, the antioxidant effect of this chelator is significantly lower than that of L1. This finding can be explained by two possible mechanisms. One mechanism is that L1 oxidizes faster than DFRA, ferrous to ferric iron and forms ferric iron complex, which is not facilitating LA peroxidation. The other mechanism is related to the much higher lipophilicity of DFRA , which a3+ and Cu2+ ions. It can be seen that the efficiency of the antioxidant activity of DFRA is higher in the case of Fe3+ than with Cu2+ which is explained by the higher affinity of the chelator for iron ions than for copper ions [The last part of our study was to investigate the effect of DFRA on redox active transition metal induced DHP oxidation. Dihydropyridines are widely used as analogues of NADH, which is a natural substrate in metabolic reactions of electron transfer in living cells ,72. Uncoper ions ,38.The antioxidant activity of DFRA in all three molecular model systems, confirms similar antioxidant activity observed in these and other models of oxidative damage with the other two chelating drugs L1 and deferoxamine ,73,74,753, 97%), ferrous sulphate , copper chloride  and H2O2 (35.5%) were obtained from Sigma-Aldrich, Moscow, Russia. Deferiprone  was received from LIPOMED Inc., Arlesheim, Switzerland. Deferasirox  was obtained from Shanghai Daeyeon Chemicals Co., Ltd., Shanghai, China, DHP 1,1′--di(propan-1-one) (99%) was synthesized according to the classic Hantzsch scheme and obtained from prof. G. Duburs, Institute of Organic Synthesis, Riga [Ascorbic acid , ferric chloride  with Asc (0.1 mM) at room temperature and by monitoring changes at the absorption spectra. The wavelength of 262 nm, which corresponds to the absorption band of Asc, was selected based on the UV-Vis spectrometry data and the analysis of the spectra. This wavelength was selected because it also corresponds to a local minimum in this region of the absorption spectra of DFRA chelate complexes with iron and copper ions. The concentrations of the reagents used in the study were selected in the way that the optical density of the solution did not exceed the detection limit  of the UV-Vis spectrometer.UV-Vis optical density spectra and kinetics were measured in ethanol solution in 1 cm quartz cuvette using a SF-2000 spectrophotometer . The influence of DFRA on the oxidation of Asc was studied by addition of various concentrations of chelator into the mixture of iron or copper salts (CuCl2O2 (0.5 M), DFRA or L1 (1 mM), and FeSO4 or CuCl2 (0.1 mM) in deuterated phosphate-saline buffer (0.1 M) (pH 7.4). The reaction was initiated by addition of hydrogen peroxide. In the case of DFRA, LA was mixed with DFRA in chloroform, then the solvent was evaporated leaving behind a film, which was dissolved in deuterated phosphate-saline buffer (pH 7.4). Then FeSO4 or CuCl2 was added and the sample was incubated for 30 min to establish equilibrium. In the case of L1, LA was dissolved in chloroform, then the solvent was evaporated and the remaining film was dissolved in deuterated phosphate-saline buffer (pH 7.4). Then L1 and FeSO4 or CuCl2 was added and the sample was incubated for 30 min. The reaction was initiated by addition of hydrogen peroxide. The 1H-NMR spectra were recorded using a Bruker AVHD-500 spectrometer (500 MHz) .The study of lipid peroxidation was carried out using a reaction mixture consisted of LA micelles (3.5 mM), H2O2 (0.2 M), DFRA (2 mM), and FeCl3 or CuCl2 (0.2 mM) in deuterated methanol. The reaction was initiated by the addition of the metal salt into the sample. Dihydropyridines are quite sensitive to external influences, such as light [1H-NMR spectra were also recorded using a Bruker AVHD-500 spectrometer (500 MHz).The investigations of dihydropyridine were carried out using a reaction mixture which consisted of 1,1′-di(propan-1-one) (DHP) (5 mM), Has light , therefoMolecular studies including the redox effects of DFRA and its metal complexes with iron and copper are of major importance for determining the general pharmacological and toxicological properties of DFRA, as well as all other drugs. Furthermore, the findings from such studies may have therapeutic implications for patients receiving DFRA and other drugs.In this study several molecular model systems of oxidative damage on Asc, LA micelles and DHP caused by iron and copper catalysis have been used for examining the effects of DFRA. The antioxidant activity of DFRA in the three molecular model systems of oxidative damage in this study, confirms previous findings in similar models and also the general antioxidant potential in biological systems of chelating drugs including DFRA, L1 and deferoxamine. However, differences remain between the chelating drugs on redox properties, affinity for metal ions including iron and copper, pharmacological and toxicological properties and also therapeutic effects.Further studies are needed to investigate the antioxidant effects of DFRA and the other iron chelating drugs in different in vitro, in vivo and clinical models of oxidative damage. It is hoped that the antioxidant properties of DFRA and other chelating drugs will increase the prospects for the development of antioxidant drugs for the treatment of many different categories of free radical pathology patients, including patients with neurodegenerative diseases, cancer and cardiac, renal, liver and other organ damage.