Materials Sciences and Applications

Journal Information
ISSN / EISSN : 2153-117X / 2153-1188
Published by: Scientific Research Publishing, Inc. (10.4236)
Total articles ≅ 1,172
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Latest articles in this journal

Prince N. Anyalebechi
Materials Sciences and Applications, Volume 13, pp 158-212; https://doi.org/10.4236/msa.2022.134011

Abstract:
Reliable information on the solubility of hydrogen in aluminum and its alloys is critical to the effort of the aluminum industry to control and ameliorate the usually deleterious effects of hydrogen on the properties and performance of pure aluminum and aluminum alloy products. Unfortunately, there is a significant disparity between published values of hydrogen solubility in pure aluminum and aluminum alloys. This is because the measurement of the extremely low soluble hydrogen concentration in aluminum and its alloys is experimentally difficult. Also, the reproducibility, accuracy, and reliability of the hydrogen solubility values are very sensitive to the measurement techniques, test conditions, chemical composition, and state of the aluminum sample. Thus, no serious discussion of the reliability of reported values of hydrogen solubility in aluminum and its alloys can be undertaken without a critical assessment of the fundamental principles of the experimental techniques used in the determination of the reported values. In this article, a critical review of the fundamental principles of the experimental techniques used in the measurement of hydrogen solubility in liquid and solid pure aluminum and aluminum alloys is presented. In addition, the reliability and possible accuracy of reported values of hydrogen solubility in solid and liquid pure aluminum are critically assessed. Empirical equations for calculating hydrogen solubility in liquid and solid pure aluminum as a function of temperature and pressure, derived from the most reliable sets of data are recommended. At 101.3 kPa (1 atm.) hydrogen partial pressure, the most reliable values of hydrogen solubility at the melting point (833 K) of pure aluminum are 0.71 cm3/100g (i.e., 6.32 × 10-5 wt.% H) and 0.043 cm3/100g (i.e., 3.81 × 10-6 wt.% H), in the liquid and solid state, respectively. So, the partition coefficient of hydrogen in pure aluminum is 0.061.
Anshebo Getachew Alemu
Materials Sciences and Applications, Volume 13, pp 22-38; https://doi.org/10.4236/msa.2022.131002

Abstract:
Scanning electrochemical microscopy (SECM) feedback mode has been used to investigate kinetics of dye regeneration in DSSC. Organic dye C343 and CW1 are used as sensitizers for nickel oxide (NiO) photoelectrochemical cells. The influence of film thickness on dye regeneration kinetics in the films for NiO/C343 for six different films was investigated. SECM was used to analyze effective rate constant, keff and reduction rate kred, absorption cross section, Φhv for the dye regeneration process. The data reveal a significant variation of keff and kred with a variation of light intensity, sample thickness and dye difference. This research found remarkable dependence of the dye regeneration kinetic parameters on illumination flux, dye types and film thickness of electrode.
Mutsumi Takahashi, Yogetsu Bando
Materials Sciences and Applications, Volume 13, pp 133-143; https://doi.org/10.4236/msa.2022.134009

Abstract:
The effectiveness and safety of the mouthguard depend on the sheet material thickness. The thickness of the thermoformed mouthguard is affected by the model undercut and the thermal shrinkage that occurs when the extruded-molded sheet is reheated. The aim of this study was to clarify the influence of the undercut amount of the model and the thickness of the sheet material on the thermal shrinkage of the extruded sheet. The mouthguard sheet used ethylene-vinyl acetate resin with a thickness of 4.0 mm (4M) and 3.0 mm (3M) and was manufactured by extrusion molding. The working models were three hard gypsum models with the undercut amount on the labial side trimmed to 0? (U0), 10? (U10), and 20? (U20). Mouthguard thickness after vacuum formation was compared between the conditions formed so that the extrusion direction was vertical (condition V) or parallel (condition P) to the model midline. Differences in the reduction rate of the mouthguard thicknesses of the labial and buccal side depending on the sheet extrusion direction, model angle, and sheet material thickness were analyzed by three-way ANOVA and Bonferroni method. The reduction rate of the thickness in condition P was significantly greater than in condition V under all conditions except U0-4M on the labial side and U0-4M and U10-4M on the buccal side. In all models, the reduction rate of the thicknesses was significantly greater in 3M than in 4M in the same extrusion direction. In both 4M and 3M, the reduction rate of the thicknesses tended to increase as the amount of undercut increased in each extrusion direction. This study suggested that a model with a large amount of undercut on the labial side or a thin sheet had a significant effect on the thermal shrinkage of the mouthguard sheet during thermoforming, which leads to the thinning of the mouthguard.
Karoline Da Silva Santana, Maria Inês Bruno Tavares
Materials Sciences and Applications, Volume 13, pp 279-299; https://doi.org/10.4236/msa.2022.135015

Abstract:
Flaxseed (Linum usitatissimum L.) is one of the oldest crops known by humans and it has been used in numerous applications, such as in the textile industry, feed formulation, fertilizers, and paper industry. However, nowadays these seeds have won an important highlight for human consumption due to their active ingredients that make them an excellent functional food. Thus, this study aimed to extract flaxseed oil, an oil rich in omega 3 and 6, characterize it by using nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR) and then encapsulate this oil in polycaprolactone (PCL) on the micro scale, using the nanoprecipitation technique and subsequently freeze-drying. To determine the mean diameter, the dynamic light scattering technique (DLS) was used, and to verify whether there was encapsulation, the pulse sequence MSE-FID, an NMR sequence in the time domain, was also used. In addition to the previously mentioned techniques, X-ray diffraction (XRD) was also employed. Flaxseed flour was also analyzed by time-domain NMR and FTIR. The results obtained by NMR show that the oil consists of fatty acid esters in the form of triglycerides in which there is the presence of esters of α-linolenic and linoleic acids, respectively ALA and LA, according to the literature. Regarding the material after encapsulation, it presented a mean diameter of 445.2 ± 41 nm and PDI of 0.674 ± 0.064, therefore classified as microparticles. Finally, using the sequence MSE-FID and the FTIR, it can be concluded that there has been the microencapsulation of flaxseed oil in the particles formed.
Gladys Ama Quartey
Materials Sciences and Applications, Volume 13, pp 334-341; https://doi.org/10.4236/msa.2022.135018

Abstract:
Ghana is rich in forest resources, of whichTerminalia catappa, a wood species of common occurrence is one. Even though sometimes it is used for decorative purposes, however, it grows in the wild. It grows in almost all the regions of the country and does well in the tropics. The parts of the tree such as the leaves, fruits and seeds have been known to be very useful for medicinal and other uses. Some work on the strength properties of the leaves and other parts has also been done, however, strength properties of the wood are yet to be explored. In this study, its mechanical properties such as bending strength, compression parallel to the grain, and shear parallel to the grain properties were determined. The British (BS 373, 1957) and American Society of Testing Materials’ specifications (ASTM D143, 1983) using testing methods for small, clear specimens of wood were used in determining the properties. The results showed that at 18% moisture content the wood has a density of 520 kg/m3 with a mean modulus of rupture of 86.04 Mpa, compressive strength parallel to the grain of 42.02 Mpa, modulus of elasticity of 10,500 Mpa, and shear strength parallel to the grain of 16.42 N/mm2. These strength properties are comparable to that of Strombosia glaucescens. Therefore, T. catappa can be used in applications where this species is used.
Paul S. Follansbee
Materials Sciences and Applications, Volume 13, pp 300-316; https://doi.org/10.4236/msa.2022.135016

Abstract:
Large-strain deformations introduce several confounding factors that affect the application of the Mechanical Threshold Stress model. These include the decrease with the increasing stress of the normalized activation energy characterizing deformation kinetics, the tendency toward Stage IV hardening at high strains, and the influence of crystallographic texture. Minor additions to the Mechanical Threshold Stress model are introduced to account for variations of the activation energy and the addition of Stage IV hardening. Crystallographic texture cannot be modeled using an isotropic formulation, but some common trends when analyzing predominantly shear deformation followed by uniaxial deformation are described. Comparisons of model predictions with measurements in copper processed using Equal Channel Angular Pressing are described.
Jiahau Yan, Burak Taskonak, John J. Mecholsky Junior
Materials Sciences and Applications, Volume 13, pp 144-157; https://doi.org/10.4236/msa.2022.134010

Abstract:
Mineralized tissues are usually constructed of nanosized materials with ordered hierarchical structures. The main reason for their high load-bearing ability is the multi-scale hierarchy. It is important to have a method for measuring the energy absorbed during the nanoscale deformation of mineralized tissues. The objective of this study was to use a combination of nanoindentation and elastic-plastic mechanics techniques to measure the damage resistance of peritubular and intertubular dentin, based on the energy consumed in the plastic deformation regime and the volume created by the indents. The control materials were soda-lime glass, gold, and poly-methyl methacrylate (PMMA). Plastic deformation energy was calculated from the plastic part of load-displacement curves. The mean values of peritubular dentin and intertubular dentin were 3.8 × 109, and 5.2 × 109 J/m3, respectively, compared to glass, PMMA, and gold which were 3.3 × 107, 1.3 × 109, and 3.1 × 109 J/m3, respectively. This method can be applied to study the resistance of mineralized tissues or organic/inorganic hybrid materials to deformation at the nanoscale.
Fei Jiang, Wen Zhang, Siyu Guo, Xin Zhang
Materials Sciences and Applications, Volume 13, pp 107-131; https://doi.org/10.4236/msa.2022.133008

Abstract:
Bacterial cellulose/polyacrylic acid (BC/PAA) pH-responsive hydrogels were prepared by free-radical polymerization (in situ) using BC as the raw material and AA as the monomer. The hydrogels were loaded with curcumin (Cur) to prepare pH-responsive intelligent medical dressings. The preparation process of the hydrogels was optimized by a single factor and response surface experiment using their swelling degree as an index. The structures of BC/PAA pH-responsive hydrogels were characterized by scanning electron microscope (SEM), Fourier Transform Infrared spectrometer (FTIR), X-ray diffraction (XRD), and tensile tester, and the swelling properties, mechanical properties, bacteriostatic properties, and drug release behavior were investigated. The results showed that the BC/PAA pH-responsive hydrogel has a three-dimensional network structure with the swelling rate up to 1600 g/g, compressive strength of up to 8 KPa, and good mechanical properties, and the drug release behavior was in line with the logistic dynamics model, and it has good inhibitory effects on common pathogens of wound infection: E. coli, S. aureus, and P. aeruginosa.
Miada Abubaker Osman, Nick Virgilio, Mahmoud Rouabhia, Frej Mighri
Materials Sciences and Applications, Volume 13, pp 63-77; https://doi.org/10.4236/msa.2022.132005

Abstract:
In this study, a design of experiments (DoE) approach was used to develop a PLA open-cell foam morphology using the compression molding technique. The effect of three molding parameters (foaming time, mold opening temperature, and weight concentration of the ADA blowing agent) on the cellular structure was investigated. A regression equation relating the average cell size to the above three processing parameters was developed from the DoE and the analysis of variance (ANOVA) was used to find the best dimensional fitting parameters based on the experimental data. With the help of the DoE technique, we were able to develop various foam morphologies having different average cell size distribution levels, which is important in the development of open-cell PLA scaffolds for bone regeneration for which the control of cell morphology is crucial for osteoblasts proliferation. For example, at a constant ADA weight concentration of 5.95 wt%, we were able to develop a narrow average cell size distribution ranging between 275 and 300 μm by varying the mold opening temperature between 106°C and 112°C, while maintaining the foaming time constant at 8 min, or by varying the mold foaming time between 6 and 11 min and maintaining the mold opening temperature at 109°C.
Clara Teixeira de Oliveira, Maria Inês Bruno Tavares
Materials Sciences and Applications, Volume 13, pp 39-53; https://doi.org/10.4236/msa.2022.131003

Abstract:
A derivation of the nanoprecipitation technique without the presence of surfactants to reduce the nanoparticle size is herein proposed. The absence of surfactant in the nanoprecipitation technique allows capturing particles with a smaller diameter than nanoparticles containing surfactants, facilitating the migration of antioxidant nanoparticles in film packaging. Biodegradable PLA nanoparticles with clove oil were produced and characterized by dynamic light scattering, zeta potential, Fourier transform infrared spectroscopy, retention efficiency, cytotoxicity, and antioxidant activity. The particle sizes obtained were smaller than those commonly produced by nanoprecipitation, monodispersed and stable for 6 months. The antioxidant activity showed that the encapsulated form of clove oil had greater antioxidant activity than unencapsulated clove oil. The addition of PLA nanoparticles decreased the cytotoxic action of eugenol, the main antioxidant component of clove oil.
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