Materials Science eJournal最新文献

{"title":"A Study of the Phase-Structural Engineering Possibilities of Coatings on D16 Alloy During Micro-Arc Oxidation in Electrolytes of Different Types","authors":"V. Subbotina, Oleg Sоbоl`, V. Belozerov, A. Subbotin, Y. Smyrnova","doi":"10.15587/1729-4061.2020.209722","DOIUrl":"https://doi.org/10.15587/1729-4061.2020.209722","url":null,"abstract":"The effect of electrolysis conditions with different electrolyte compositions on the growth kinetics, phase-structural state, and hardness of coatings obtained by microarc oxidation (MAO) on the D16 aluminum alloy (base – aluminum, main impurity Cu) was studied. An analysis of the results obtained showed that the choice of the type of electrolyte and the conditions for the MAO process makes it possible to vary the growth kinetics and phase-structural state of the coating on the D16 aluminum alloy within a wide range. For all types of electrolytes, with an increase in the content of KOH, Na 2 SiO 3 , or KOH+Na 2 SiO 3 , the growth rate of MAO coatings increases. It was found that in MAO coatings obtained in an alkaline (KOH) electrolyte, a two-phase (γ−Al 2 O 3 and α−Al 2 O 3 phases) crystalline state is formed. An increase in the KOH concentration leads to an increase in the relative content of the α–Al 2 O 3 phase (corundum). During the formation in a silicate electrolyte, the phase composition of MAO coatings with an increase in the content of liquid glass (Na 2 SiO 3 ) changes from a mixture of the γ−Al 2 O 3 phase and mullite (3Al 2 O 3 ∙2SіO 2 ) to an X-ray amorphous phase. The use of a complex electrolyte leads to a two-phase state of the coating with a large (compared to an alkaline electrolyte) shift of the γ−Al 2 O 3 →α−Al 2 O 3 transformation towards the formation of the α−Al 2 O 3 phase. It was determined that the value of hardness correlates with the content of the α−Al 2 O 3 phase in the MAO coating, reaching the maximum value of 1620 kg/mm 2 at the highest content (about 80 vol. %) of the α−Al 2 O 3 phase. Two types of dependences of the coating thickness on the amount of electricity passed were revealed. For the amount of passed electricity 10–50 A-h/dm 2 , the thickness dependence is determined as 4.2 μm/(A-h/dm 2 ), which suggests the basic mechanism of electrochemical oxidation during the formation of a coating. For the amount of electricity transmitted 50–120 A-hour/dm 2 , the thickness dependence is determined by a much smaller value of 1.1 μm/(A-hour/dm 2 ). This suggests a transition to a different mechanism of coating formation − the formation of a coating with the participation of electrolysis components","PeriodicalId":18341,"journal":{"name":"Materials Science eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86900992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Study of the Influence of Polyvinyl Pyrrolidone Concentration in the Deposition Electrolyte on the Properties of Electrochromic Ni(OH) 2 Films","authors":"V. Kotok, V. Kovalenko","doi":"10.15587/1729-4061.2020.210857","DOIUrl":"https://doi.org/10.15587/1729-4061.2020.210857","url":null,"abstract":"Electrochromic devices are actuation elements of smart windows and allow saving the energy needed to cool the premises. Electrochemical deposition can significantly reduce the cost of electrochromic deposition. This paper discusses an electrochemical method of deposition based on nickel hydroxide from an electrolyte containing nickel nitrate and polyvinylpyrralidone (PVP). The electrochromic films were obtained in a galvanostatic mode at different PVP concentrations. As a result of the studies, it has been shown that the presence of PVP in the deposition electrolyte significantly affects the properties of the resulting electrochromic films. Moreover, the properties of the resulting films strongly depend on the used PVP concentration. Thus, at low concentrations, the addition of PVP causes an improvement in electrochromic and electrochemical characteristics, including stability in the properties of films. While at high concentrations of PVP, the electrochemical and electrochromic characteristics deteriorate significantly up to their almost complete disappearance. The paper proposes a possible mechanism that explains the improvement in the characteristics of the films obtained from the solutions with low PVP concentrations. This mechanism consists in improving the wettability of the substrate, increasing the contact area of the deposit with the substrate and, as a consequence, improving the adhesion and a decrease in the contact resistance at the conductive oxide – Ni(OH) 2 film boundary. Also, the work has found the range of optimal PVP concentrations for an electrolyte containing 0.1 М Ni(NO 3 ) 2 , which is 0.5–2 %","PeriodicalId":18341,"journal":{"name":"Materials Science eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89686845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Patterns of Influence Exerted by the Side Walls of a Vibratory Sieve on the Motion of a Loose Mixture Flow","authors":"M. Piven, Aleksandr Spolnik, T. Sychova, A. Piven","doi":"10.15587/1729-4061.2020.208640","DOIUrl":"https://doi.org/10.15587/1729-4061.2020.208640","url":null,"abstract":"The influence of the side walls of a vibratory sieve on the motion of a loose mixture flow has been investigated. The regularities have been established of the flow motion parameters on the walls’ height, the resistance of their surfaces, the length and distance between them. The condition has been defined for the occurrence, degree, character, as well as the region of the side walls’ influence on the mixture motion over the entire area of a sieve. Increasing the height of the walls, the length and resistance of their surfaces increases the surface density and reduces the longitudinal velocity of a mixture near the near-wall region, causing the occurrence of the transverse velocity component and the uneven distribution of the specific load of the sieve. For the wall’s steady parameters, there is a threshold of distance between them, at which the near-wall regions of uneven loading begin to interact with each other, thereby enhancing their influence on the flow. There occur the under-loaded and over-loaded sites in the sieve that differ in the magnitude of deviations and area. The uneven loading area reaches 83 % of the sieve area while the magnitude of deviations in the specific loading is 26 %. A condition of the influence exerted by the side walls on a flow is exceeding the minimum values of the parameters: a wall height, h >4·10 –3 m; the resistance of a wall surface, C z >2 kg/m 2 ·s; a wall length, l >0.5 m. The side walls’ influence leads to the formation of a near-wall region of the sieve’s under-loaded and over-loaded sites, whose deviations and area are the same. The magnitude of the wall’s region of influence increases in proportion to the sieve length and acquires the shape of a rectangular triangle. To reduce the influence of the side walls, it is necessary to reduce the resistance of their surfaces, the sieve length, and to increase its width, to avoid the threshold distance between the walls and a simultaneous growth of their parameters. The patterns in the side walls’ influence underlie the improvement of vibratory-sieve separators and the substantiation of their operation modes","PeriodicalId":18341,"journal":{"name":"Materials Science eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76286501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cytotoxic Effect of PEI-Coated Magnetic Nanoparticles on the Regulation of Cellular Focal Adhesions and Actin Stress Fibres","authors":"Kaarjel K. Narayanasamy, J. Price, M. Merkhan, Ajile Elttayef, J. Dobson, N. Telling","doi":"10.2139/ssrn.3558242","DOIUrl":"https://doi.org/10.2139/ssrn.3558242","url":null,"abstract":"Abstract The biocompatibility of surface-coated magnetic nanoparticles (MNPs) is key to their successful use in biomedical applications. Polyethyleneimine-coated MNPs (MNP-PEIs) provide improved in vitro nucleic acid transfection efficiency and are safer compared to conventional chemicals. Commercial cell toxicity assays are useful for end-point and high-throughput screening, however, they only reports cells that have undergone an extreme toxic response leading to cell death. Cell toxicity is a complex process which can be expressed in many forms, through morphological, metabolic, and epigenetic changes. This study explores the effect of magnetic transfection with MNP-PEIs and an external magnetic field on cell toxicity, by studying particle internalization, changes in cellular morphology, and cell adhesion. We show that MNP-PEIs induce cell stress through a dose-dependent increase in cell adhesion via the overexpression of vinculin and formation of actin stress fibres. While the presence of PEI was the main contributor to increased cell stress, free PEI polyplexes induced higher toxicity compared to PEI bound to MNPs. MNPs without PEI coating however did not adversely affect cells, suggesting a chemical effect instead of a mechanical one. In addition, genes identified as being associated with actin fibre regulation and cell adhesion showed significant increases in expression from MNP-PEI internalization. From these results, we identify anomalous cell behaviour, morphology, and gene expression after interaction with MNP-PEIs, as well as a safe dosage to reduce acute cell toxicity.","PeriodicalId":18341,"journal":{"name":"Materials Science eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75584979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Temperature Dependence of Double Shockley Stacking Fault Behavior in Nitrogen-Doped 4h-Sic Studied by In-Situ Synchrotron X-Ray Topography","authors":"F. Fujie, S. Harada, K. Hanada, H. Suo, H. Koizumi, Tomohisa Kato, M. Tagawa, T. Ujihara","doi":"10.2139/ssrn.3542923","DOIUrl":"https://doi.org/10.2139/ssrn.3542923","url":null,"abstract":"Abstract We observed the behavior of double Shockley stacking faults (DSFs) in 4H-SiC crystals with nitrogen concentrations of 1.0 × 1019–2.6 × 1019 cm−3 over an extensive temperature range (1380–1910 K) by in-situ synchrotron X-ray topography. For a nitrogen concentration of 2.6 × 1019 cm−3, the expansion velocity of the DSFs exponentially increased with temperature in the range from 1370 to 1650 K. In contrast, at a nitrogen concentration of 1.0 × 1019 cm−3, this velocity decreased above 1610 K and the DSFs shrank above 1730 K. The DSF energy, the magnitude of which is the driving force on partial dislocation (PD) movement, was quantitatively estimated from the radius of the curvature of bowed-out partial PDs pinned by threading screw dislocations (TSDs), showing a positive temperature dependence and lying in the range from −0.6 to 0.8 mJ/m2 for 1630–1910 K at a nitrogen concentration of 1.0 × 1019 cm−3. The DSF expansion and shrinkage behavior can be understood by the simple temperature and nitrogen concentration dependence of the DSF energy.","PeriodicalId":18341,"journal":{"name":"Materials Science eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79576459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ductility Limit Diagrams for Superplasticity and Forging of High Temperature Polycrystalline Materials","authors":"Wei Zhang, Yanfei Gao, Zhili Feng, Xin Wang, Siyu Zhang, Lan Huang, Zaiwang Huang, Liang Jiang","doi":"10.2139/ssrn.3542976","DOIUrl":"https://doi.org/10.2139/ssrn.3542976","url":null,"abstract":"Abstract A mechanistic understanding of the ductility limit diagrams is of critical importance, but it still remains elusive for a multitude of high temperature materials processing techniques, such as superplastic forming and hot forging. The relevant failure modes for the former are necking at high strain rates and intergranular cavitation at low strain rates, while those for the latter include the competition between longitudinal fracture and shear band. The comparison between the Arrhenius processes for grain boundary diffusion and grain interior creep defines a length scale that dictates whether the grain boundary cavity growth is diffusive or creep-constrained. A quantitative assessment of these damage evolution processes leads to the delineation of the dominant parametric spaces for individual failure modes, and thus superplasticity and forging limit diagrams are derived and compared to available experiments in literature.","PeriodicalId":18341,"journal":{"name":"Materials Science eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73978385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metal Complexation of Deferasirox Derivatives: A Solid State and Equilibrium Study","authors":"P. Buglyó, I. Nagy, Gergő Tamás Ferenczik, Linda Bíró, E. Farkas, A. Bényei","doi":"10.1016/j.poly.2020.114780","DOIUrl":"https://doi.org/10.1016/j.poly.2020.114780","url":null,"abstract":"","PeriodicalId":18341,"journal":{"name":"Materials Science eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75943457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Scaffold Derived from GGTA1 and CMAH Gene Knockout Pigs Provoked Little Inflammatory Responses in a Humanized Pig Model","authors":"C. yen, H. Tai, Su-Hei Peng, Tien-Shuh Yang, C. Tu","doi":"10.2139/ssrn.3595735","DOIUrl":"https://doi.org/10.2139/ssrn.3595735","url":null,"abstract":"Abstract The attempt to produce a porcine small intestinal submucosa extracellular matrix (SIS-ECM) that is fully biocompatible was made. Samples of SIS-ECM were prepared from either wild-type (WT) or double-gene knockout (dKO) pigs without α-Gal and N-glycolylneuraminic acid (Neu5Gc) antigens. The scaffolds, which were sutured into cuts made in the longissimus muscle of the dKO pigs, were expected to exhibit xeno-reactions through natural antibodies as in a human response. A process was established to manufacture ameliorating acellular porcine SIS-ECM implants with consistent quality characteristics, which were assured by analyzing the level of residual DNA, the glycosaminoglycan content, and histochemical stains. Once implanted, the acellular SIS-ECM from the WT pigs caused a significant increase in serum IL-6 levels in the dKO recipient pigs, indicating a host defense through immune reactions. The levels remained unchanged when preparations from the dKO pigs were used. The results together with pathological evidences suggested that dKO pigs without antigenic response to α-Gal or Neu5Gc can serve as biocompatible SIS-ECM donors or as animal models for testing anthropomorphic immune responses to biomedical devices.","PeriodicalId":18341,"journal":{"name":"Materials Science eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81846708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hierarchical Zeolite Single Crystal Reactor for Unprecedented Catalytic Efficiency","authors":"Ming‐Hui Sun, Jian Zhou, Zhi-Yi Hu, Li‐Hua Chen, Li-Yuan Li, Yangdong Wang, Zaiku Xie, S. Turner, G. van Tendeloo, T. Hasan, B. Su","doi":"10.2139/ssrn.3534404","DOIUrl":"https://doi.org/10.2139/ssrn.3534404","url":null,"abstract":"As a size and shape selective catalyst, zeolites are widely used in petroleum and fine chemicals processing. However, their small micropores severely hinder molecular diffusion and are sensitive to coke formation. Hierarchically porous zeolite single crystals with fully interconnected, ordered and tunable multimodal porosity at macro-, meso- and micro-length scale like in leaves offer the ideal solution. However, their synthesis remains highly challenging. Here we report a versatile confined zeolite crystallization process to achieve these superior properties. Such bio-inspired zeolite single crystals lead to significantly improved mass transport properties by shortening the diffusion length while maintaining shape selective properties, endowing them with an unprecedentedly high efficiency of zeolite crystals, enhanced catalytic activities and cycle time, highly reduced coke formation and reduced deactivation rate in bulky-molecule reactions and methanol-to-olefins process. Their industrial utilization can lead to the design of innovative and intensified reactors and processes with highly enhanced efficiency and minimum energy consumption.","PeriodicalId":18341,"journal":{"name":"Materials Science eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79966992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Study of the Electrolyte Composition Influence on the Structure and Properties of MAO Coatings Formed on AMg6 Alloy","authors":"V. Subbotina, Oleg Sоbоl`, V. Belozerov, Ubeidulla F. Al-Qawabeha, T. Tabaza, Safwan Moh`d Al-Qawabah, V. Shnayder","doi":"10.15587/1729-4061.2020.205474","DOIUrl":"https://doi.org/10.15587/1729-4061.2020.205474","url":null,"abstract":"The influence of electrolysis conditions at different electrolyte compositions on the phase formation and properties of coatings obtained by microarc oxidation (MAO) on an aluminum alloy AMg6 was studied. For electrolysis, three types of electrolytes were used: alkaline electrolyte ((KOH) solution in distilled water), silicate electrolyte (with different percentages of Na 2 SiO 3 component) and complex alkaline silicate electrolyte with liquid glass (1÷12 g/l Na 2 SiO 3 ) and potassium hydroxide (1÷6 g/l KOH). An analysis of the results showed that the choice of electrolyte type and conditions of the microarc oxidation process allows a wide variation in the phase-structural state, thickness and properties of the AMg6 aluminum alloy. The criterion for the expected phase-structural state of the coatings as a result of microarc oxidation is the completeness of the γ–Al 2 O 3 →α–Al 2 O 3 transformation process during coating formation. The use of an alkaline electrolyte does not allow achieving a high hardness of the coating due to the formation of the γ-Al 2 O 3 phase and the absence of thermodynamic conditions for the γ–Al 2 O 3 →α–Al 2 O 3 transition. When using a silicate electrolyte, it is possible to significantly increase the growth rate of the coating, but at the same time, the presence of a large specific Si concentration stimulates the formation of mullite and an amorphous-like phase. The use of a combined alkaline silicate electrolyte (with different percentages of KOH+Na 2 SiO 3 ) with a low content (6 g/l) of Na 2 SiO 3 in solution stimulates the formation of mullite. This is manifested to the greatest extent with the lowest content (1 g/l) of the KOH component. At a higher content (2 g/l) of the KOH component, the processes characteristic of an alkaline electrolyte become dominant. This leads to an incomplete transformation reaction and the formation of only the γ-Al 2 O 3 phase. The achievement of the thermodynamic conditions of the γ–Al 2 O 3 →α–Al 2 O 3 conversion became possible with an increase in the specific Na 2 SiO 3 content in the electrolyte solution to 12 g/l. In this case, MAO coatings were formed on the AMg6 alloy with the highest hardness of 1500 kg/mm 2 and high electric strength of 12 V/μm","PeriodicalId":18341,"journal":{"name":"Materials Science eJournal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79162915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}