Search

Objectives: The objective was to evaluate the polymerization efficiency of different bulk-fill resin-based composites cured by monowave and polywave light-curing units, by assessment of the degree of conversion and Vickers microhardness at different depths. Method and materials: Two commercially available bulk-fill resin-based composites were used: Filtek One Bulk Fill Restorative (3M ESPE) and Tetric N-Ceram Bulk Fill (Ivoclar Vivadent). The light-curing units utilized were two LED light-curing units: a monowave LED light-curing unit (BlueLEX LD-105, Monitex) and a polywave LED light-curing unit (Twin Wave GT-2000, Monitex). For each test, 20 cylindrical specimens (4 mm diameter, 4 mm thickness) were prepared from each bulk-fill resin-based composite using a split Teflon mold. Ten specimens were light-cured by the monowave light-curing unit and the other ten were light-cured by the polywave light-curing unit according to the manufacturer's recommendations. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATRFTIR) was used to assess the degree of conversion, and a Vickers microhardness tester was used to assess Vickers microhardness. Statistical analysis was performed using three-way ANOVA and Tukey post-hoc tests (P < .05). Results: The degree of conversion and Vickers microhardness in bulk-fill resin-based composites containing only camphorquinone as photoinitiator were similar when cured with either monowave or polywave light-curing units. However, bulk-fill resin-based composites containing a combination of photoinitiators exhibited significantly higher degree of conversion and Vickers microhardness when cured with a polywave light-curing unit. Although all groups showed statistically significant differences between the top and bottom surfaces regarding degree of conversion and Vickers microhardness, all of them showed bottom/top ratios > 80% regarding degree of conversion and Vickers microhardness. Conclusion: The polywave light-curing unit enhanced the polymerization efficiency of bulk-fill resin-based composites especially when the latter contained a combination of photoinitiators, but does not prevent the use of a monowave light-curing unit. [ABSTRACT FROM AUTHOR]

Thermal embrittlement is a key concern for the structural integrity of engineering components. Monitoring thermal embrittlement may indicate susceptibility to crack initiation and growth and therefore act as a damage precursor. In this study the correlation between thermoelectric power (also known as the Seebeck Coefficient) and the hardness of thermally aged 2507 super duplex stainless steel was demonstrated, showing the suitability of using thermoelectric power as a proxy measurement for embrittlement. This article presents a continuous high-temperature thermoelectric power monitoring system that is suitable for installation on large engineering assets. Using temperature gradients in the sample of < 6.5 °C a measurement standard deviation of 5.8 nV/°C was possible, which was sufficient to monitor the ~ 850 nV/°C increase in thermoelectric power that occurred in this study. [ABSTRACT FROM AUTHOR]

Zirconia/alumina composite has been prepared by chemical route followed by solid state sintering route by adding various percentage of yttria from 2 to 6 mol%. The dielectric constant and dielectric loss at room temperature have been calculated as 207, 108, 206 and 0.053, 0.031, 0.046 for 2 mol%, 4 mol% and 6 mol% yttria, respectively, at a frequency of 1 kHz. Nyquist plot analysis suggests the grain–grain boundary effects of the composite material. The complex impedance study gave the knowledge about the kind of relaxations that existing within the ceramic composite. A decrease of activation energy with an increase in frequency for higher content of yttria in the sample was noticed from the variation between AC conductivity versus inverse of the temperature, and this gave rise to positive temperature coefficient of resistance (PTCR) and negative temperature coefficient of resistance (NTCR) behavior in the composite at various frequencies. An increase in yttria content has resulted in a decrease in optical band gap of the composites. [ABSTRACT FROM AUTHOR]

Copyright of GeSec: Revista de Gestao e Secretariado is the property of Sindicato das Secretarias e Secretarios do Estado de Sao Paulo (SINSESP) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of the study was to evaluate the effect of two distinct light-polymerization protocols, used by dental students, on the placement time and polymerization efficiency of bulk-fill (BF) and conventional (CRC) resin-based composites (RBCs). Thirty dental students participated in this study. Each student was asked to complete four Class II RBC restorations using two different types of RBCs (BF and CRC) paired with two distinct light-polymerization protocols: one using 1200 mW/cm2 irradiance (P1200) and one using 800 mW/cm2 irradiance (P800). Manufacturer instructions for curing times relative to these irradiance levels were adhered to. The restorations were retrieved, sectioned and Vickers microhardness (VMH) was measured at specific reading points. The placement time was recorded for each procedure. Multivariate analysis of variance and Bonferroni post hoc test were used for data analysis. Bulk-fill RBCs were associated with significantly shortened placement times (P < 0.001). VMH values of CRC-P800 were significantly higher compared to all other groups (P < 0.02). Across all groups tested, the VMH values at the deepest reading points exceeded those at the occlusal surfaces by over 80 %. The use of BF RBCs with a P1200 light-polymerization protocol reduced students' procedural times while maintaining effective polymerization of the restorations. [ABSTRACT FROM AUTHOR]

Dental caries is a commonly occurring non-communicable disease throughout the world that might compromise the quality of any individual's life. Glass ionomer cements (GIC) are the most acceptable restorative materials due to their ease of manipulation, minimal tooth loss and least invasive strategy; however, they lack mechanical stability that has become a point of concern. Nanoparticles (NPs) are an outstanding option for modifying and enhancing the properties of dental materials. The focus of this study was to prepare novel, biocompatible titania dioxide (TiO2) NPs as a dental-restorative material using an efficient probiotic Bacillus coagulans. The prepared NPs were incorporated into glass ionomer restorative material at varying concentrations and investigated for cell viability percentage, microhardness and surface morphology. Results indicated that pure 100% anatase phase TiO2 NPs with particle size of 21.84 nm arranged in smooth, spherical agglomerates and clusters forms. These NPs depicted cell viability > 90%, thus confirming their non-cytotoxic behavior. GIC restorative materials reinforced by 5% titania (TiO2) NPs demonstrated the highest microhardness in comparison to the control group and other experimental groups of the study. Surface morphology analysis revealed a reduction in cracks in this novel dental-restorative material supporting its compatible biological nature with better hardness strength and negligible crack propagation. Overall, these results indicated that TiO2 NPs produced using a biological approach could be easily used as restorative materials in dental applications. [ABSTRACT FROM AUTHOR]

Changes in the structure, phase composition, chemical composition, Vickers microhardness, and contact modulus of elasticity of a high-strength titanium α + β-alloy of the VST2 martensitic class during quenching after heating in the 700 – 1000°Ñ range were studied using the methods of optical microscopy, XRD phase analysis, microindentation, and thermodynamic calculations in ThermoCalc. The experimental data were in good agreement with the results of thermodynamic calculations. Arelationship between changes in the microhardness and contact modulus of elasticity of VST2 alloy, quenched from 700 – 1000°C, and the structure and phase composition of the alloy during quenching was established. [ABSTRACT FROM AUTHOR]

Aim: Occurrence of denture stomatitis and prosthesis breakage are common problems faced by elderly people wearing removable dentures. To overcome this, several attempts are made to improve the denture material by addition of antimicrobials without compromising original properties. The aim of the study was to evaluate flexural strength and microhardness of self-cured polymethyl methacrylate (PMMA) denture base resin after addition of Vaccinium macrocarpon (commonly called as cranberry), extract as antimicrobial, at varying proportions. Study Setting and Design: Experimental in vitro study. Materials and Methods: Frozen cranberry fruits were subjected to extraction process in the presence of aqueous solvents. Lyophilized extract was added in proportions of 0, 0.5, 1.0, 1.5, and 2.0 dry wt/wt % into polymer of self-cure PMMA denture base resin. Based on cranberry inclusion, the study comprised one control (0%) and four test groups (0.5%–2%) with total of 100 samples. A three-point bending test for flexural strength was done for fifty study samples (n = 10). Surface of fractured samples was analyzed using a scanning electron microscope (SEM). Microhardness was determined using Vickers hardness test. Statistical Analysis Used: One-way statistical ANOVA test was done to find the difference between groups, followed by Tukey’s post hoc test for multiple pairwise comparison. Results: Flexural strength ranged from 66.80 to 69.28 MPa, and a statistically insignificant difference was observed between groups (P > 0.05). SEM evaluation showed uniformly dispersed strands of cranberry extract in PMMA matrix. With higher concentration, less voids were seen. Vickers microhardness value significantly decreased from 15.96 in the control group to 14.57 with 2% cranberry addition (P < 0.05). Conclusion: Incorporation of cranberry extract into self-cure PMMA denture base resin, up to 2 dry wt %, did not decline the flexural strength. However, there was a significant decrease in Vickers microhardness values when compared against the control group (0% cranberry inclusion).

Aim: Occurrence of denture stomatitis and prosthesis breakage are common problems faced by elderly people wearing removable dentures. To overcome this, several attempts are made to improve the denture material by addition of antimicrobials without compromising original properties. The aim of the study was to evaluate flexural strength and microhardness of self-cured polymethyl methacrylate (PMMA) denture base resin after addition of Vaccinium macrocarpon (commonly called as cranberry), extract as antimicrobial, at varying proportions. Study Setting and Design: Experimental in vitro study. Materials and Methods: Frozen cranberry fruits were subjected to extraction process in the presence of aqueous solvents. Lyophilized extract was added in proportions of 0, 0.5, 1.0, 1.5, and 2.0 dry wt/wt % into polymer of self-cure PMMA denture base resin. Based on cranberry inclusion, the study comprised one control (0%) and four test groups (0.5%--2%) with total of 100 samples. A three-point bending test for flexural strength was done for fifty study samples (n = 10). Surface of fractured samples was analyzed using a scanning electron microscope (SEM). Microhardness was determined using Vickers hardness test. Statistical Analysis Used: One-way statistical ANOVA test was done to find the difference between groups, followed by Tukey's post hoc test for multiple pairwise comparison. Results: Flexural strength ranged from 66.80 to 69.28 MPa, and a statistically insignificant difference was observed between groups (P > 0.05). SEM evaluation showed uniformly dispersed strands of cranberry extract in PMMA matrix. With higher concentration, less voids were seen. Vickers microhardness value significantly decreased from 15.96 in the control group to 14.57 with 2% cranberry addition (P < 0.05). Conclusion: Incorporation of cranberry extract into self-cure PMMA denture base resin, up to 2 dry wt %, did not decline the flexural strength. However, there was a significant decrease in Vickers microhardness values when compared against the control group (0% cranberry inclusion). [ABSTRACT FROM AUTHOR]

Introduction: Mechanized endodontic treatment is an advent that has been constantly evolving. Objective: to characterize the instruments through scanning electron microscopy and perform mechanical tests of 45º bending, buckling and microhardness of ProTaper instruments. Materials and Methods: 10 nickel titanium instruments from each System were used: ProTaper Universal (PTUN), ProTaper Gold (PTGO), Protaper Ultimate (PTUL) and Protaper Next (PTNE). The SEM analysis was carried out using a SEM FEG quanta FEI 250. For the 45º bending and buckling tests, an EMIC LD 200MF universal testing machine was used. Vickers microhardness was performed using a Micromet 2003 Bueler microhardness meter. The results were subjected to the Shapiro-Wilks normality test for subsequent ANOVA testing, the significance level adopted was 5%. Results: The instruments studied presented the following order in relation to flexibility: PTUL>PTGO>PTUN>PTNE. The buckling resistance of the instruments presented the following order: PTUN>PTGO>PTNE=PTUL. The Vickers microhardness presented the following order PTUN= PTNE>PTGO=PTUL. Conclusion: PTUL instruments were the most flexible and PTUN were the most resistant to buckling. The microhardness of controlled memory instruments (gold wire) presents a softer alloy. The instruments had a good surface finish. [ABSTRACT FROM AUTHOR]

A new organic and nonlinear optical material namely (4-chlorophenyl) (4-hydroxypiperidin-1-yl) methanone [HPCP] was synthesized from the mixture of 4-hydroxypiperidiene, triethylamine, and 4-chlorobenzoyl chloride by solution growth technique. The 3D structure of the title crystal has been derived using the X-ray diffraction (XRD) spectrum. The compound was crystallized in the orthorhombic crystal system with non-centrosymmetric space group Pca21. Optical properties of the as-grown compound have been elucidated through 1H-NMR, UV-Visible, FTIR, and PL spectral studies. The melting point, stages of mass decay, and thermal stability of the synthesized material were obtained by TG/DTA thermal analysis. Vickers microhardness test was performed to comprehend its mechanical strength. The second harmonic generation (SHG) efficiency was estimated by employing Q-switched high energy, Nd: YAG the laser source, and the SHG efficiency was found to be 1.73 times that of KDP, the reference crystal. [ABSTRACT FROM AUTHOR]

Laser beam welding (LBW) has been widely employed to acquire defect-free joints between aluminum alloys for a wide range of applications, especially within the automotive industry. The current study aims to examine the effect of laser power on the final microstructure, as well as the mechanical properties of laser beam welded AA5754 and AA6063 aluminum alloys. Lap joints of the abovementioned alloys were performed using a 1030-nm Yb:YAG LBW process with a laser power of 3000 W and 3500 W. The microstructure of base metals (BM), heat-affected zone (HAZ), and fusion zone (FZ) was investigated by means of visible light microscopy (VLM) under non-polarized and polarized light, as well as of scanning electron microscopy (SEM) in conjunction with energy-dispersive spectroscopy (EDS), while the crystal structure was evaluated by X-ray diffraction (XRD). The mechanical properties of welded samples were investigated through Vickers microhardness and tensile shear tests. Furthermore, the fracture surfaces were observed under a stereoscope and a SEM. The metallographic examination revealed the presence of small defects, such as pores, with a diameter ranging from 20 to 50 μm, and microcracks, whose length ranged from 300 to 400 μm. Reducing the laser power was observed to affect the weld geometry, and more specifically the penetration, that was found at 900 μm for the samples welded with 3500 W and 333 μm for those welded with 3000 W. It was also noticed that reducing the laser power resulted in decreased width of the HAZ; the samples welded with 3000 W had a HAZ width of approximately 400–500 μm, while the samples welded with 3500 W had a HAZ width of 500 μm. Finally, applying higher laser power was observed to improve the mechanical properties of welded samples, resulting in higher relative ductility and fewer microhardness fluctuations within the FZ. The specimens welded with 3500 W presented increased tensile shear force and displacement of 3.8 kN in comparison to 3.4 kN of the joints welded with 3000 W. [ABSTRACT FROM AUTHOR]

Objectives A comparable performance between bulk-fill composites (BFCs) and progressively inserted conventional resin composite (CRC) has been observed in previous studies. However, a significant number of dental institutions in India continue to employ incremental techniques for RC restorations during preclinical studies. But as BFCs are gaining popularity, they may soon be a part of the curriculum for dental students. The aim of this study was to assess the microhardness and the polymerization efficiency of bulk-fill composites versus CRC in class II slot preparations restored by second-year dental students on ivorine mandibular first molar teeth with high-intensity (HI) and low-intensity (LI) light-curing units using the standard mesial slot preparation technique. Material and Methods Fifty preclinical dental students of second year of a dental college were recruited for the study on a voluntary basis. During their preclinical instructions, all participants were taught and made to practice the handling and curing techniques for two-surface RC restorations for 4 months. Each student was asked to perform four RC restorations: CRC-HI, CRC-LI, BFC-HI, and BFC LI. Assessment of microhardness was done using the Vickers microhardness (VMH) test. Statistical analysis One-way and multivariate analysis of variance and Bonferroni 's post hoc test tests were used for data analysis. Results The results showed a significant decrease in the VMH readings in the horizontal axis, progressing from the uppermost to the lowermost positions (p > 0.05). In all the examined groups, the VMH values at the deepest reading locations were found to be higher than 80% of the values observed at the occlusal surface reading locations. Statistically significant associations were seen between the RC type and the light source used in the VMH readings conducted (p > 0.05). However, no significant correlation was identified between the type of light source and the vertical VMH readings (p > 0.05). Conclusion Instructing dental students to place RC restorations using CRC or BFC materials together with both HI and LI light-curing protocols is safe and can be considered for preclinical studies. [ABSTRACT FROM AUTHOR]

Abstract Background Recently, universal single-shade resin composites have become increasingly available in the dental market. The modification of their composition can have an inadvertent effect on their physical and surface properties, and subsequently determinantal effect on their clinical function and longevity. Therefore, this study aimed to evaluate the effect of different finishing and polishing (F/P) systems on surface roughness (Ra), surface gloss (GU), and Vickers microhardness (VMH) of universal single-shade RBCs. Materials and methods Four commercial RBCs were used; the universal single-shade RBCs were Omnichroma, Charisma® Diamond ONE, and Vittra APS Unique, and a conventional nanocomposite Filtek™ Z250 XT was used as a control. The 3 F/P systems were Sof-Lex™ XT, Enhance®/PoGo®, and Diacomp® Plus Twist. A total of 160 discs were used for the 3 F/P system groups for all RBCs (n = 10). After F/P, the Ra, GU, and VMH were assessed. The data were analyzed using 2-way ANOVA at p-value

The slow evaporation solution growth technique is used to grow single crystals of 2-phenylbenzimidazole (2PBMZ). The crystal belongs to the monoclinic system with space group C2/c, which is revealed through the single crystal XRD. The cutoff wavelength and optical band gap energy of the 2PBMZ crystal were observed at 568 nm and 1.96 ev respectively. The Vickers (Hv) hardness number, yield strength and stiffness constant are calculated, which is found to increase with the applied load. The Z-scan technique with He–Ne laser (632.8 nm) has been used to study the third-order nonlinear optical property of 2PBMZ crystal. [ABSTRACT FROM AUTHOR]

This study analyzed the impact of heat treatments on ASTM A131 ABS DH36 steel's microstructure and hardness behavior. In its initial state, we characterized the chemical composition, microstructure, tensile strength, and hardness. Several samples underwent heat treatments, with heating temperatures of 500 °C, 750 °C, and 1000 °C, followed by cooling in brine at 1 °C and 29 °C. Microstructure analysis including optical microscopy, scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), and Vickers microhardness profiling. At 500 °C, the microstructure remained mostly unchanged, with ferrite and pearlite colonies, and no significant hardness alterations. At temperatures of 750 °C and above 1000 °C, martensite formation during cooling dominated, resulting in higher hardness as it increased. The highest average hardness of 364 HV, a 127% increase from the initial state, was observed in samples treated at 1000 °C. Except for quenching at 500 °C, heat treatments significantly impacted microstructure and hardness, with minimal differences between cooling temperatures applied.

Shot peening (SP) is a surface cold hardening process used on metals to enhance life under cyclic stress. In this case, SP was applied to SAE5160H samples of steel quenched tempered in oil at 460 °C used for leaf springs. This study shows the residual surface stresses measured through X-ray diffraction (XRD) and the microhardness variation through the perpendicular-to-the-peened surface using a combination of metallographic preparation and Vickers microhardness (HVN). This combination of techniques makes possible measuring the SP effect in perpendicular-to-the-treated surface. A residual stress of -365.8 ± 78 MPa measured by XRD and a maximum microhardness of 525± at 92.7 HVN on the surface were obtained for the SP material. Alternatively, an average of 54.2 ± 54.3 MPa residual stress measured by XRD and 433 ± 39.5 HVN were obtained for the As-it-is samples. In addition, corrosion electrochemical potential tests showed that SP increases the corrosion potential, which makes this process undesirable if the SP component is exposed to aggressive environments. Moreover, the As-it-is samples presented not statistically significant HVN difference in the measured points. The combination of experimental techniques allows estimating hardness change in perpendicular-to-the treated surface separated by as little as 10 µm but with a simpler specimen preparation than other techniques such as XRD or strain gauges. Such a combination can be an alternative for estimating residual stresses through depth.

Shot peening (SP) is a surface cold hardening process used on metals to enhance life under cyclic stress. In this case, SP was applied to SAE5160H samples of steel quenched tempered in oil at 460 °C used for leaf springs. This study shows the residual surface stresses measured through X-ray diffraction (XRD) and the microhardness variation through the perpendicular-to-the-peened surface using a combination of metallographic preparation and Vickers microhardness (HVN). This combination of techniques makes possible measuring the SP effect in perpendicular-to-the-treated surface. A residual stress of -365.8 ± 78 MPa measured by XRD and a maximum microhardness of 525± at 92.7 HVN on the surface were obtained for the SP material. Alternatively, an average of 54.2 ± 54.3 MPa residual stress measured by XRD and 433 ± 39.5 HVN were obtained for the As-it-is samples. In addition, corrosion electrochemical potential tests showed that SP increases the corrosion potential, which makes this process undesirable if the SP component is exposed to aggressive environments. Moreover, the As-it-is samples presented not statistically significant HVN difference in the measured points. The combination of experimental techniques allows estimating hardness change in perpendicular-to-the treated surface separated by as little as 10 µm but with a simpler specimen preparation than other techniques such as XRD or strain gauges. Such a combination can be an alternative for estimating residual stresses through depth. [ABSTRACT FROM AUTHOR]

This study investigated the effect of powder-pack boronizing on the microstructure, hardness, and wear and corrosion behavior of AISI 304L austenitic stainless steel. Powder-pack boronizing was carried out using Baybora-1 boronizing agent for 2, 4, 6, and 8 h at 950 °C. Boronized AISI 304L steel exhibited a flatter and thinner morphology depending on the alloying elements. XRD analysis showed the presence of CrB, Cr2B, Ni2B, Ni3B, α-Mn, MnB, and α-SiO2 phases in addition to FeB and Fe2B. Boronizing time increased the boride layer thickness from 20.6 to 50.6 μm. The highest Vickers microhardness value of 1316.1 HV0.1 was observed in the sample boronized for 2 h. In the wear tests applied with 80, 220, and 400 mesh Al2O3 abrasives under 10, 20, and 30 N loads, the boronized samples exhibited approximately 1.7-10 times more wear resistance than non-boronized steel. In the corrosion test performed in 10% H2SO4 acid solution, corrosion resistance increased with metal boride layer thickness. The sample boronized for 2 h was seen to have the lowest weight loss. [ABSTRACT FROM AUTHOR]

Solid-state additive friction stir deposition (AFSD) is a thermomechanical-based additive manufacturing technique. For this study, AFSD was utilized to produce aluminum alloy 6061 (AA6061) blocks with varying layer thicknesses (1 mm, 2 mm, and 3 mm). The mechanical properties were assessed through uniaxial tensile tests and Vickers microhardness measurement, and statistical analysis was employed to investigate differences among data groups. The results revealed that the deposition layer thickness influences tensile properties in the building (Z) direction, while the properties in the X and Y directions showed minor differences across the three AFSD blocks. Furthermore, variations in tensile properties were observed depending on the sample orientation in the AFSD blocks and its depth-wise position in the part in the building direction. The microhardness values decreased non-linearly along the building direction, spread across the width of the part's cross-section, and highlighted that the deposition layer thickness significantly affects this property. The 1 mm block exhibited lower average microhardness values than the 2 mm and 3 mm blocks. The temperature histories and dynamic heat treatment are influenced by the deposition layer thickness and depend on the location of the point being studied in the part, resulting in variations in the microstructure and mechanical properties along the building direction and across the part's width. [ABSTRACT FROM AUTHOR]

Radiation hardening is studied for stainless austenitic and ferritic-martensitic chromium steels after ion and neutron irradiation at various temperatures. Austenitic and ferritic-martensitic steels irradiated up to 30 dpa in various nuclear reactors and ion accelerators are studied at various temperatures. A change in Vickers microhardness is used as the radiation hardening parameter. A methodology is developed that allows one to determine the ion irradiation parameters, which ensure the radiation hardening of ferritic-martensitic and austenitic steels, as close as possible to the radiation hardening of the same steels under neutron irradiation. A transferability function is introduced to connect the irradiation temperatures for ion and neutron irradiation that provides the same radiation hardening. On the basis of the obtained experimental data, after ion and neutron irradiation the transferability functions are determined for the investigated austenitic and ferritic-martensitic steels, which connect the temperatures for ion and neutron irradiation and provide the same radiation hardening at a given damage dose. [ABSTRACT FROM AUTHOR]

This study investigated the impact of samarium and lanthanum fluorides (SmF3 and LaF3) on the physical and mechanical properties of Tl0.8Hg0.2Ba2Ca2−xRxCu3O9−δ−yFy superconducting phases (specifically the (Tl, Hg)-1223 phase), where R = Sm and La, with 0.00   ≤     x     ≤   0.10 . The superconducting samples were synthesized using the solid-state reaction method. X-ray diffraction (XRD) verified the formation of the (Tl, Hg)-1223 phase without altering its tetragonal structure. Scanning electron micrographs (SEM) reveal the improvement of the grain size and inter-grain connectivity as Sm and La contents increased up to x = 0.025 . The electrical properties of (Tl, Hg)-1223 were studied using I-V and electrical resistivity measurements. Improved superconducting transition temperature (Tc) and transport critical current density (Jc) were observed up to x = 0.025 , beyond which they decreased substantially. Vickers microhardness (Hv) measurements were performed at room temperature to investigate their mechanical performance with various applied loads ( 0.49 – 9.80 N) and times ( 10 – 90   s). For both substitutions, the mechanical properties were enhanced up to an optimal value at x = 0.025 . All samples exhibited normal indentation size effect (ISE) behavior. The proportional sample resistance (PSR) model best explained Hv values among five theoretical models. Dislocation creep was the primary creep mechanism in the samples, according to indentation creep studies. [ABSTRACT FROM AUTHOR]

In the present paper, plasma-assisted physical vapor depositions (PAPVDs) have been used to extract the TiN and titanium aluminum nitride (TiAlN). Further, plasma nitriding (PN) has been used prior to thin-film deposition of TiN on AISI 304 stainless steel material using intentional biasing (in the coating). PAPVD is integrated to investigate the thermal resistant effect coating of AISI 304 stainless steel by TiN coating using finite-element analysis. The morphology of elements on the coating was studied by field emission scanning electron microscopy, X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy. From XRD analysis, it has been observed that at the coated zone Ti, TiN was found on the AISI 3O4 stainless steel. The results in microhardness through the Vickers microhardness tester have been measured up to 350 Hv for the base sample at a 10 g load. Moreover, TiN/(PN + TiN) coated samples were measured with an average microhardness of 2220, 963, and 720 Hv for the nitride sample. In addition to this, the microhardness of TiAlN was found up to 1890 and 2400 Hv for different samples. The thickness of the film is around 1.4279 µm (TiN) and 1.888 µm (TiAlN) in 1 h of deposition. [ABSTRACT FROM AUTHOR]

A new eugenyl dimethacrylated monomer (symbolled BisMEP) has recently been synthesized. It showed promising viscosity and polymerizability as resin for dental composite. As a new monomer, BisMEP must be assessed further; thus, various physical, chemical, and mechanical properties have to be investigated. In this work, the aim was to investigate the potential use of BisMEP in place of the BisGMA matrix of resin-based composites (RBCs), totally or partially. Therefore, a list of model composites (CEa0, CEa25, CEa50, and CEa100) were prepared, which made up of 66 wt% synthesized silica fillers and 34 wt% organic matrices (BisGMA and TEGDMA; 1:1 wt/wt), while the novel BisMEP monomer has replaced the BisGMA content as 0.0, 25, 50, and 100 wt%, respectively. The RBCs were analyzed for their degree of conversion (DC)-based depth of cure at 1 and 2 mm thickness (DC1 and DC2), Vickers hardness (HV), water uptake (WSP), and water solubility (WSL) properties. Data were statistically analyzed using IBM SPSS v21, and the significance level was taken as p < 0.05. The results revealed no significant differences (p > 0.05) in the DC at 1 and 2 mm depth for the same composite. No significant differences in the DC between CEa0, CEa25, and CEa50; however, the difference becomes substantial (p < 0.05) with CEa100, suggesting possible incorporation of BisMEP at low dosage. Furthermore, DC1 for CEa0–CEa50 and DC2 for CEa0–CEa25 were found to be above the proposed minimum limit DC of 55%. Statistical analysis of the HV data showed no significant difference between CEa0, CEa25, and CEa50, while the difference became statistically significant after totally replacing BisGMA with BisMEP (CEa100). Notably, no significant differences in the WSP of various composites were detected. Likewise, WSL tests revealed no significant differences between such composites. These results suggest the possible usage of BisMEP in a mixture with BisGMA with no significant adverse effect on the DC, HV, WSP, and degradation (WSL). [ABSTRACT FROM AUTHOR]

In this study, the impact of adding samarium iron garnet (Sm3Fe5O12; SmIG) nanoparticles to the (Bi1.6Pb0.4)Sr1.9Ca0.9Y0.2Cu2.1O8+δ ((Bi, Pb)-2212) superconductor was investigated. The conventional solid-state reaction method was utilized to synthesize (SmIG)x(Bi, Pb)-2212 phase with different concentrations (x = 0, 0.25, 0.5, 0.75, 1, and 2 wt%). The structure, the morphology, and the elemental composition were tested using X-ray powder diffraction spectroscopy (XRD), scanning electron microscopy (SEM), and dispersive X-ray spectroscopy (EDX), respectively. Filling of pores and voids validated the impact of the added nano-SmIG on intergrain connections. The enhancement in oxygen content was verified by iodometric titration analysis. The superconducting transition temperature (Tc) and the critical current density (Jc) showed best enhancement with the addition of nano-SmIG up to x = 0.75 wt%, having values of 91.02 K and 373.95 A/cm2, respectively. The fluctuations in the superconducting properties were explained via X-ray photoelectron spectroscopy (XPS) by studying the elemental composition and oxidation states for all elements. Vickers microhardness (Hv) investigations were carried out at different applied loads and indentation time of 20 s, where Hv reached its highest value at x = 0.25 wt%. Based on Hv values, the modified proportional sample resistance (MPSR) model offered the most suitable theoretical model to elucidate the experimental data. [ABSTRACT FROM AUTHOR]

New Ti alloys are being developed to obtain materials with better properties for biomedical applications. In order to avoid complications caused for the presence of Al and V ions in the blood stream, novel alloys have been developed without these two elements. Mo and Nb are two non-toxic β-stabilizing elements used in Ti alloys because they decrease the elastic modulus and improve corrosion resistance. Thus, this study investigated the influence of Nb addition in Ti-xNb-5Mo alloy (x = 0, 10, 20, 30 %wt) on microstructure, structure, and selected mechanical properties. The samples were characterized after annealing, and the results showed the decrease of α phase and growth of β phase with the addition of Nb. The ω phase in the alloy containing 20% Nb was also detected. The samples’ elastic modulus and microhardness tended to decrease with increasing of the β phase, except for the Ti–20Nb–5Mo alloy due to phase hardening ω. The average crystallite size of the α and β phases increased with the addition of Nb.

Nanosized precursor powders of (1 – x)ZrSiO4‒xZrO(OH)2 are synthesized by the sol-gel method with the separate precipitation of components to obtain (1 – x)ZrSiO4‒xZrO2 ceramic composites. The thermal behavior of precursor powders is studied by differential scanning calorimetry and thermogravimetry (DSC/TG). Ceramic composites with a high level of microhardness are obtained by sintering powders, preliminarily calcined at 850°C, in air in the temperature range 1000‒1300°C. In the future, such ceramic composites can be used as matrices for solidification and isolating high-level waste (HLW). [ABSTRACT FROM AUTHOR]

Aim: The aim of the present study was to compare the remineralization efficacy of fluoridated and nonfluoridated toothpaste on artificially demineralized enamel. Materials and Methods: Buccal surface of eighty extracted human premolars was treated with demineralizing solution for 96 h and they were randomly distributed into four groups. Group 1 was control, Group 2 was brushed with Xyliwhite toothpaste (fluoride free), Group 3 was brushed with Superbee Propolis toothpaste (fluoride free), and Group 4 was brushed with Amflor Pro toothpaste (Fluoridated). Brushing was performed for 2 min twice daily with a powered toothbrush for 7 days. After every brushing, the specimens were cleaned and stored in artificial saliva at room temperature. The enamel surface microhardness was measured with Vickers hardness test postdemineralization and posttreatment and a comparative analysis was made. Results: One-way analysis of variance F-test showed a statistically significant difference in remineralization efficacy among the groups (P < 0.001). Tukey's post hoc test showed that Group 2, Group 3, and Group 4 have higher remineralization efficacy as compared to control (P < 0.001). Maximum remineralization efficacy was seen with Group 4. Conclusion: Fluoridated and nonfluoridated toothpastes have the potential to remineralize the demineralized enamel surface. [ABSTRACT FROM AUTHOR]

Aim: The aim of this study was to evaluate and compare the compressive strength, Vickers microhardness number, and wear resistance of amalgam (DPI), Filtek Z350 nanohybrid (3M ESPE), and Zirconomer (Shofu) restorative materials after 24 h and 3 months. Methodology: The restorative materials were divided into Zirconomer (Group I), Filtek Z350 (Group II), and amalgam (Group III). These materials were placed in cylindrical molds to prepare the specimens. The specimens were stored in distilled water at 37°C. The specimens were tested at 24 h and 3 months for compressive strength, wear resistance, and microhardness. Results: Group I showed significantly less maximum load (N) and compression strength (MPa) when compared with Group III (control) and Group II (P < 0.01). There was no significant difference in microhardness between the three groups. Group I showed significantly more wear (weight loss [g]) and wear (weight loss [%]) when compared with Group III (control) and Group II. Conclusion: The study concludes that amalgam and nanohybrid composite performed better than Zirconomer at the end of 24 h and 3 months. [ABSTRACT FROM AUTHOR]

Two approaches to the synthesis of nanosized precursor powders 0.5LaPO4·nH2O–0.5ZrO(OH)2 and 0.5LaPO4·nH2O–0.5Y(OH)3 for the fabrication of ceramic composites 0.5LaPO4–0.5ZrO2 and 0.5LaPO4–0.5Y2O3 were used. In the first case, sol-gel synthesis of components (LaPO4·nH2O, ZrO(OH)2 or Y(OH)3) was carried out separately by reverse precipitation technique. In the second case, reverse precipitation was used too but without separate preparation of sols of the components. The results of the synthesis were compared by XRD analysis, thermal behavior of precursor powders by DSC/TG technique, as well as Vickers microhardness values of 0.5LaPO4–0.5ZrO2 and 0.5LaPO4–0.5Y2O3 ceramic composites. [ABSTRACT FROM AUTHOR]

Aim: The aim of this study was to evaluate and compare the compressive strength, Vickers microhardness number, and wear resistance of amalgam (DPI), Filtek Z350 nanohybrid (3M ESPE), and Zirconomer (Shofu) restorative materials after 24 h and 3 months. Methodology: The restorative materials were divided into Zirconomer (Group I), Filtek Z350 (Group II), and amalgam (Group III). These materials were placed in cylindrical molds to prepare the specimens. The specimens were stored in distilled water at 37°C. The specimens were tested at 24 h and 3 months for compressive strength, wear resistance, and microhardness. Results: Group I showed significantly less maximum load (N) and compression strength (MPa) when compared with Group III (control) and Group II (P < 0.01). There was no significant difference in microhardness between the three groups. Group I showed significantly more wear (weight loss [g]) and wear (weight loss [%]) when compared with Group III (control) and Group II. Conclusion: The study concludes that amalgam and nanohybrid composite performed better than Zirconomer at the end of 24 h and 3 months.

Introduction: We aimed to examine the effect of amoxicillin and azithromycin suspensions on the microhardness of sliver-reinforced glass ionomer and nano-resin modified glass ionomer (GI). Method: Thirty discs (2 mm height x 4 mm diameter) of each type of GI were prepared, which were randomly assigned to amoxicillin, azithromycin, and artificial saliva groups. Microhardness was evaluated by Vickers hardness test before and after three immersion cycles. Results: The overall model (P < 0.001), before/after intervention (P < 0.001), intervention group (type of antibiotic) (P = 0.013), and type of glass ionomer (P

The current study investigated the effect of adding yttrium iron garnet (Y 3 Fe 5 O 12 ; YIG) nanoparticles to the (Bi 1.8 Pb 0.4)Sr 2 Ca 2.1 Cu 3.2 O y ((Bi,Pb)-2223) superconductor. The classical solid-state reaction technique was used to synthesize the nano-(YIG) x /(Bi,Pb)-2223 composites (0.00 ≤ x ≤ 2.00 wt.%). X-ray diffraction (XRD) confirmed the formation of tetragonal (Bi,Pb)-2223 as the major phase. The morphology and elemental composition of the synthesized samples were investigated using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), respectively. Iodometric titration analysis proved that the addition of nano-YIG increased the oxygen content in the CuO 2 planes. The critical transition temperature (T c) and the critical current density (J c) increased with the nano-YIG addition up to x = 0.25 wt.% with values of 119.25 K and 638.37 A/cm2, respectively. X-ray photoelectron spectroscopy (XPS) revealed the elemental composition and oxidation state of all elements in the prepared samples. Room temperature Vickers microhardness (H v) measurements were performed at different applied loads (0.49–9.80 N) and a duration time of 20 s. The best enhancement in Vickers microhardness (H v) was achieved at x = 2.00 wt.%. The modified proportional sample resistance (MPSR) model provided the best theoretical analysis at the plateau limit region based on Vickers microhardness (H v) observations. Moreover, nano-YIG addition into the (Bi,Pb)-2223 superconductor adversely affected several mechanical parameters such as the elastic modulus (E), yield strength (Y), and fracture toughness (K). [ABSTRACT FROM AUTHOR]

To manifest the effect of hard magnetic Ba0.5Sr0.5Fe12O19 nanoparticles on the mechanical performance of the (Bi,Pb)-2223 superconducting phase, nano-(Ba0.5Sr0.5Fe12O19)x/Bi1.8Pb0.4Sr2Ca2Cu3.2O10+δ, with x = 0.00, 0.01, 0.02, 0.03, 0.04, 0.05, 0.10, and 0.20 wt%, were synthesized using a conventional solid-state reaction method. The X-ray diffraction (XRD) data revealed that adding nano-(Ba0.5Sr0.5Fe12O19) to the host (Bi,Pb)-2223 phase preserved the orthorhombic structure. The porosity (P%) calculations revealed a decrease until x = 0.04 wt%, which suggests that the addition of nano-(Ba0.5Sr0.5Fe12O19)x reduces the number of voids and improves inter-grain connections, as confirmed by SEM micrographs. The superconducting transition temperature (Tc) increased to 112 K with the inclusion of nano-(Ba0.5Sr0.5Fe12O19) up to x = 0.04 wt%. Vickers microhardness (HV) measurements were conducted at various applied loads (0.245–9.800 N) and a duration time of 45 s. The HV number increased with the addition of x up to x = 0.04 wt% but then decreased with further addition. Various models were employed for analysis and modelling of Vickers hardness (HV) versus test load (F), including Meyer's law, Hays–Kendall (H–K) model, the elastic/plastic deformation (EPD) model, the proportional sample resistance (PSR) model, the modified proportional sample resistance (MPSR), and indentation-induced cracking (IIC) model. It was found that the PSR model was the most appropriate theoretical model for describing the microhardness of nano-(Ba0.5Sr0.5Fe12O19)x/(Bi,Pb)-2223 composites. Moreover, the elastic modulus (E), yield strength (Y), fracture toughness (K), brittleness index (B), and elastic stiffness coefficient (C11) were estimated as a function of the inclusion of nano-(Ba0.5Sr0.5Fe12O19)x. Furthermore, the indentation creep test (time-dependent Vickers microhardness) revealed that the dislocation creep mechanism exists in composite samples with low concentrations (x < 0.05 wt%), whereas the dislocation climbs creep mechanism was observed for x ≥ 0.05 wt%. [ABSTRACT FROM AUTHOR]

To compare between the effect of partial substitution of lead ions (Pb4+ and Pb2+) at thallium (Tl) site in Tl0.8-xHg0.2PbxBa2Ca2Cu3O9−δ superconductor; two different compounds, lead (II) oxide (PbO) and lead (IV) oxide (PbO2), were used for the synthesis of the superconducting samples. Samples with nominal compositions Tl0.8-xHg0.2PbxBa2Ca2Cu3O9−δ, with x = 0.00, 0.05, 0.10, 0.15, and 0.20, were synthesized via solid state reaction technique. The x-ray diffraction (XRD) results showed that the partial substitution of both lead ions has not affected the tetragonal structure. Moreover, the volume fraction was increased from 75.95% to 90.38% and 89.41% as x increased up to 0.20 for PbO and PbO2 substitutions, respectively. The scanning electron microscopy (SEM) images demonstrated better grain connectivity and rectangular-shaped plates, supporting the phase formation of (Tl,Hg)-1223. The energy-dispersive x-ray (EDX) analysis revealed good agreement between the nominal and real compositions. Moreover, the elemental composition and oxidation states were proved by x-ray photoelectron spectroscopy (XPS). Both the superconducting transition temperature (Tc) and critical current (Jc) showed enhancement at x = 0.5 and 0.1 for PbO and PbO2 substituted samples, respectively. Vickers microhardness (Hv) measurements were used to examine the mechanical properties of the composites under a range of applied loads (0.49–9.8 N). All the prepared composites revealed the normal indentation size effect. The proportional sample resistance model proved to be the best model for interpreting the experimental data for the prepared samples. [ABSTRACT FROM AUTHOR]

Bu çalışmada Bi-2223 tozlar farklı peletizasyon basınç değerleri ile külçe formuna getirilmiş ardından külçeler 840ºC’de 36 saat tavlanmıştır. Basıncın Bi-2223 külçelerin yapısal, mekanik ve elektriksel özellikleri üzerine etkileri incelenmiştir. Yapısal analizlerin değerlendirilmesi için X-ışını Kırınımı (XRD) spektroskopisi ölçümleri kullanılmıştır. Mekanik analizler için oda sıcaklığında Vickers Mikrosertlik ölçümleri yapılmıştır. Elektriksel analizlerde ise dört kontak I-V ölçümleri kullanılmıştır. Elde edilen sonuçlara göre, Bi-2223 kristal faz yoğunluğunun, sertlik değerinin ve elektrik taşıma kapasitesinin basınca ciddi bir şekilde bağlı olduğu görülmüştür. Bu bağlamda, basıncın artması ile sertlik değerlerinin kristal yapıdaki faz geçişlerine ve yüzey artık basınç gerilim bölgelerinin artışına bağlı olarak yükseldiği tespit edilmiştir. Ayrıca, hesaplanan elastisite modülü ve akma dayanımı gibi genel mekanik performans değerlerinin basınca bağlı olarak arttığı gözlemlenmiştir. Bu bulgu kristal yapıda hali hazırda var olan kovalent ve özellikle iyonik bağ kuvvetlerinin artmasının sonucu olabilir. Bununla birlikte, numunelerin plato limit bölgelerinde yükten bağımsız mikrosertlik değerleri Meyer yasası, Orantılı Numune Direnç (OND) ve Indentation Induced Cracking (IIC) yöntemleri ile analiz edilmiştir. Analiz sonucunda IIC modelin gerçek mikrosertlik değerlerini incelemede daha başarılı olduğu bulunmuştur. Kritik akımın uygulanan basıncın artması ile düştüğü gözlemlenmiştir. Örneklerin yoğunlukları Arşimet yasası kullanılarak ölçülmüştür. Teknolojik kullanım alanına bağlı olarak külçe Bi-2223 örneklerin üretiminde uygulanması gereken optimum basınç değeri detaylarıyla tartışılmıştır.

The impact of adding the orthoferrite NdFeO3, at the nanoscale, on the (Cu0.5Tl0.5)Ba2Ca2Cu3O10–δ phase formation, microstructure, electrical and mechanical performance was studied. The nano-(NdFeO3)x/(CuTl)-1223 composites, with x = 0.00, 0.25, 0.50, 0.75, 1.00, and 2.00 wt.%, were prepared using the solid-state reaction technique. The X-ray diffraction (XRD) confirmed that supplementing the host (CuTl)-1223 phase with nano-NdFeO3 did not alter the unit cell parameters (a and c) and preserved the tetragonal structure. SEM micrographs suggested that the inclusion of nano-NdFeO3 reduced the number of voids and boosted the inter-grain connections. The energy-dispersive X-ray (EDX) spectra revealed the elemental compositions of the various superconductor composites. The superconducting transition temperature (Tc) and the critical current density (Jc) increased with the inclusion of nano-NdFeO3 up to x = 0.50 wt.%. X-ray photoelectron spectroscopy (XPS) spectra analysis revealed the elemental composition and oxidation state of all elements. The Vickers microhardness (Hv) measurements were analyzed and compared with five different theoretical models. According to Hv measurements, the modified proportional sample resistance (MPSR) model provided the best theoretical analysis of Hv within the plateau limit regions. Moreover, various mechanical parameters were estimated as a function of the inclusion of nano-NdFeO3. The indentation creep test showed that the composite samples with high nanoparticle concentration (x > 0.50 wt.%) have dislocation creep mechanism, while those with x ≤ 0.50 wt.% followed a dislocation climbs creep mechanism. A comparison between NdFeO3 nanoparticles and other magnetic ferrites and nano-magnetic oxides was reported. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of the sintering temperature on Vickers microhardness and three-point flexural strength values of two multi-layered zirconia materials. Multi-layered zirconia systems with four distinct layers were selected: DD cube ONE ML (4Y-TZP) and DD cubeX2 ML (5Y-TZP). In total, 96 plate-shaped A2-shade specimens were obtained using individual layers of these two zirconia materials. The individual layers were then divided equally into batches with three different sintering temperatures (1300, 1450, and 1600 °C), and the Vickers microhardness was assessed. Another group of 72 bar-shaped specimens was prepared from the same materials. These were similarly divided into three different sintering temperatures, and the flexural strength was assessed. SEM was used to conduct fractographic analyses. The data were analyzed using SPSS 24.0 software with a p-value < 0.05. The microhardness and flexural strength of 4Y-TZP were higher than those of the 5Y-TZP at all the sintering temperatures. A significant difference was found in the microhardness and flexural strength values between groups sintered at different sintering temperatures (p < 0.05). The highest microhardness and flexural strength values were found at 1450 °C (p < 0.05). The microhardness values of different layers were not significantly different (p > 0.05). The sintering temperature and type of ceramic material significantly affected the microhardness and flexural strength. However, the layers did not significantly affect the microhardness. [ABSTRACT FROM AUTHOR]

This study evaluated the structural changes of enamel treated by the Regenerate system and carbon dioxide (CO2) laser against acid challenge. Thirty human enamel slabs were prepared and assigned into three groups: Group I: untreated (control); Group II: treated with the Regenerate system; and Group III exposed to CO2 laser. All specimens were subjected to an acid challenge (pH 4.5–7.0) for 14 days. Specimens were evaluated and compared at 120 points using five Raman microspectroscopic peaks; the phosphate vibrations ν1, ν2, ν3, and ν4 at 960, 433, 1029, and 579 cm−1, respectively, and the carbonate at 1070 cm−1, followed by Vickers microhardness test. The ratio of carbonate to phosphate was correlated to the equivalent microhardness numbers. The intensities of phosphate peaks ν1, ν2, and ν4 were reduced in all groups post-acid challenge, while the carbonate and ν3 were significantly increased (p < 0.000). Surfaces treated by Regenerate exhibited higher peak intensity of phosphate and carbonate before and after pH-cycling (p < 0.05). The mineral content in enamel had a direct effect on tissue microhardness, and the CO2-lased surfaces showed a reduced carbonate content and higher microhardness values. Both approaches induced surface changes that can protect enamel against acid challenge resulting in a significant benefit for dental healthcare. [ABSTRACT FROM AUTHOR]

A suitable mixture of Ba(NO3)2 and Al powders, known as pyrotechnic mixture, was burned to deposit pure BaAl2O4 and Ni-BaAl2O4 coatings on low-carbon steel by a new explosive spray coating method. Ni-5Al is a bonding coating material commonly used in thermal spraying to deposit ceramics on metal substrates to achieve strong coating-substrate adhesion. In addition, because it is hard in nature, this material has the potential to impart toughness to a brittle composite. Therefore, Ni-5Al powder was added to the explosive spray charge to deposit a Ni-BaAl2O4 composite coating. Various characterization techniques, such as x-ray diffraction, field emission scanning electron microscopy with energy-dispersive spectroscopy analysis, transmission electron microscopy (TEM), Vickers hardness test, scratch test, image analysis, and roughness estimation were used to compare various properties of the two coatings. It was found that the Ni-based globules are uniformly distributed in the Ni-BaAl2O4 coating. BaAl2O4 and Ba phases were observed in the pure BaAl2O4 coating, while Ni, BaAl2O4 and Ba2Al2O5 phases were mainly formed in the Ni-BaAl2O4 coating. The formation of Ni-Fe and Ni-Al based compounds and the interdiffusion of materials in the interface region of this type of coating significantly improved the coating-substrate adhesion. The TEM analysis confirmed the presence of brittle crystalline and amorphous phases in both coatings. The overall crystallinity of Ni-BaAl2O4 was higher than that of the pure BaAl2O4 coating material. The increase in hardness and reduction in crack formation in the Ni-BaAl2O4 composite also suggests an improvement in toughness. In addition, the average surface roughness and porosity of the Ni-BaAl2O4 coating were lower than that of the pure BaAl2O4 coating. The addition of Ni-5Al to the feedstock improved the mechanical properties of the explosively deposited BaAl2O4-based coating. [ABSTRACT FROM AUTHOR]

Pure and Cr doped L-asparagine monohydrate (LAM) single crystals were grown by evaporation controlled solution growth technique. SCXRD, Hirshfeld surface and fingerprint plot were performed for grown crystals. High transmittance, increase in optical bandgap and hardness were observed as result of Cr doping. Therefore, Cr doping makes LAM a better candidate for device fabrication and optoelectonics applications. [Display omitted] • Effect of Cr doping in LAM crystal grown by solution method was investigated. • High transmittance and lower cutoff wavelength were observed in UV–Vis analysis. • Intermolecular interactions were investigated by Hirshfeld surface analysis. • Cr doping has changed the 'soft' nature of crystal to 'hard' nature. • Pits were created on smooth surface of pure crystal due to Cr addition. Pure and chromium (Cr) doped L-asparagine monohydrate (LAM) single crystals were grown by using evaporation controlled solution growth technique. XRD analysis confirmed the orthorhombic crystal system with space group P2 1 2 1 2 1 of grown crystals. Cr-incorporation decreased the cell parameters and unit cell volume of the crystals. Intermolecular interactions were analysed through Hirshfeld and fingerprint studies. SEM analysis showed the appearance of pits on the smooth surface of pure crystal due to Cr-addition. UV–Vis analysis showed high transparency, low cut-off and direct band gap of 5.42 eV and 5.51 eV for pure and Cr doped crystals, respectively. Fundamental functional groups were identified by FTIR and Raman spectroscopy. The thermal stability and melting point of the crystals were investigated using TGA/DSC analysis. The dielectric constant for doped LAM was increased to 44 as compare to dielectric constant of pure crystal which was 32. Both crystals showed low dielectric loss, having values 0.04 and 0.006 for pure LAM and doped crystals, respectively. In Vickers microhardness test, Cr doping was found to change the nature of pure LAM crystal from 'soft' to 'hard' as Meyer's index changed from 2.48 to 1.24. [ABSTRACT FROM AUTHOR]

Radiation hardening is studied for stainless austenitic and ferritic-martensitic chromium steels after ion and neutron irradiation at various temperatures. Austenitic and ferritic-martensitic steels irradiated up to 30 dpa in various nuclear reactors and ion accelerators are studied at various temperatures. A change in Vickers microhardness is used as the radiation hardening parameter. A methodology is developed that allows one to determine the ion irradiation parameters, which ensure the radiation hardening of ferritic-martensitic and austenitic steels, as close as possible to the radiation hardening of the same steels under neutron irradiation. A transferability function is introduced to connect the irradiation temperatures for ion and neutron irradiation that provides the same radiation hardening. On the basis of the obtained experimental data, after ion and neutron irradiation the transferability functions are determined for the investigated austenitic and ferritic-martensitic steels, which connect the temperatures for ion and neutron irradiation and provide the same radiation hardening at a given damage dose.

Solid-state additive friction stir deposition (AFSD) is a thermomechanical-based additive manufacturing technique. For this study, AFSD was utilized to produce aluminum alloy 6061 (AA6061) blocks with varying layer thicknesses (1 mm, 2 mm, and 3 mm). The mechanical properties were assessed through uniaxial tensile tests and Vickers microhardness measurement, and statistical analysis was employed to investigate differences among data groups. The results revealed that the deposition layer thickness influences tensile properties in the building (Z) direction, while the properties in the X and Y directions showed minor differences across the three AFSD blocks. Furthermore, variations in tensile properties were observed depending on the sample orientation in the AFSD blocks and its depth-wise position in the part in the building direction. The microhardness values decreased non-linearly along the building direction, spread across the width of the part’s cross-section, and highlighted that the deposition layer thickness significantly affects this property. The 1 mm block exhibited lower average microhardness values than the 2 mm and 3 mm blocks. The temperature histories and dynamic heat treatment are influenced by the deposition layer thickness and depend on the location of the point being studied in the part, resulting in variations in the microstructure and mechanical properties along the building direction and across the part’s width.

Purpose: Rapid sintering technology has become one of the most direct methods for shortening the manufacturing time of zirconia restorations. This study aimed to explore the aging resistance of rapid-sintered 5 mol% yttria-partially-stabilized zirconia (5Y-PSZ).Methods: Specimens were made from two types of 5Y-PSZ material and subjected to rapid sintering (RS) and conventional sintering (CS). After in vitro aging for 5 h, morphology observation, grain size measurement, and phase composition analysis were performed. The mechanical properties were evaluated by biaxial, three-point flexural tests, and the Vickers microhardness test. Results were analyzed by 3-way ANOVA.Results: Both the RS group and the CS group had a dense microstructure. The tested zirconia ceramics had different grain sizes, which were affected by the interaction between the sintering method and aging. Both groups revealed the same characteristic peaks of the cubic phase after aging. Regardless of the sintering method used, there was no significant difference in the mechanical properties of the tested zirconia before and after aging.Conclusion: The rapid-sintered 5Y-PSZ materials had a microstructure, phase composition and mechanical properties similar to those of conventional sintered materials. The characteristics of the materials prepared using the two sintering methods did not change significantly after aging. [ABSTRACT FROM AUTHOR]

Introduction: We aimed to examine the effect of amoxicillin and azithromycin suspensions on the microhardness of sliver-reinforced glass ionomer and nano-resin modified glass ionomer (GI). Method: Thirty discs (2mm height x 4mm diameter) of each type of GI were prepared, which were randomly assigned to amoxicillin, azithromycin, and artificial saliva groups. Microhardness was evaluated by Vickers hardness test before and after three immersion cycles. Results: The overall model (P < 0.001), before/after intervention (P < 0.001), intervention group (type of antibiotic) (P=0.013), and type of glass ionomer (P < 0.001) showed significant differences among study groups (P < 0.001). Post hoc test showed only non-significant before/after difference for Azithromycin and artificial saliva (control) groups regarding nano resin-modified GI. Conclusion: We found significant microhardness loss for sliver reinforced GI in comparison to nano resin-modified GI after the immersion cycles. Yet, sliver reinforced GI would have higher level of microhardness than nano resin-modified GI after the immersion cycles. Longer time studies are required to assess trend of microhardness loss. [ABSTRACT FROM AUTHOR]