Journal of Material Sciences & Engineering

Alloys possessing a shape memory effect and mechanical characteristics similar to the behavior of living tissues have been already used for years as the material for production of medical devices, including implants, for example stents, without the need for additional devices except catheter-carrier. However, most of these alloys contain elements (including on its surface) which is toxic for organism. To satisfy the requirements of biochemical compatibility, the alloy should contain only safe elements as alloy components, which include: Ti, Nb, Ta, Zr. The possibility of obtaining of Ti-Nb-Ta-Zr thin wire was investigated. The structure was determined with the use of the optical microscope, X-ray diffractometer, scanning electron microscope (SEM) and Auger spectrometer. Optimal conditions for smelting were chosen. It was noted that a uniform structure was obtained for all compositions, before and after homogenizing annealing. The ingots have a dendritic structure. Niobium and zirconium were uniformly distributed throughout the sample, tantalum was concentrated in the dendrites themselves, titanium was predominantly in the regions between the dendritic axes, but is also found in it. X-ray diffractometry indicates that the elements of the alloy were not distributed in it by separate fragments, but were united in a single structure. The optimal annealing temperature of Ti-(20-30)Nb- (10-13)Ta-5Zr alloys was noted in the range from 600 to 900°C. The grain boundaries after plastic deformation and heat treatment were not identified in a microstructural analysis, which indicates that there was no recrystallization. It is possible that nanostructure was formed. The morphology of wires of any composition after drawing shows a high heterogeneity, two types of surfaces of different composition alternate - areas with a high content of carbon and with a high content of oxygen were observed. After mechanical treatment the surface, its uniformity increases.

Metal casting is the mother of Zimbabwean industries since their performance is mainly hinged upon cast components. An overview of the Zimbabwean foundry industry showing its state of the art including annual production, number of employees, technology, material, quality and diversity of castings, and common markets is presented. The Zimbabwean foundries were then compared with global leading countries in performance. Challenges faced by the Zimbabwean foundries were identified and potential development strategies were suggested.

This paper is a brief review of different tactile sensors based on piezo-resistive mechanism developed in recent times. The topics which are briefly covered are crystalline silicon-based sensors, flexible graphene based sensors, Carbon Nano Tubes (CNT) based flexible sensors, patterned PDMS thin film and self-healing materials for sensors.

The aim of this work is to combine two methods for removing nitrate ions from concentrated aqueous solutions. This involves chelating and then reducing NO3- by EDTE modified carbon paste electrode (EDTA-CPE). We find that in the absence of EDTA on the carbon paste electrode surface, the nitrate reduction is almost impossible. The reduction of nitrate ions was invested on the surface of the EDTA-CPE, the cyclic voltammograms recorded in electrolytic medium 0.1 M KCl, shows two reduction peaks, the first at -0.2 V, attributed to the reduction of nitrite ions (NO2-) and the second one at 0.8 V which corresponds to the reduction of nitrate to nitrite ions.

Dilatometry has been used to confirm that the reversion of deformation-induced martensite in Type 304 stainless steel occurs principally sin the temperature range 425 to 650°C, and to show that the reversion is a thermal or not diffusion controlled. An attempt to correlate the change in length of cold-drawn 304 wire samples on heating to 800°C with the martensite content determined from the measured saturation magnetization was only qualitatively successful. The heat of reversion of martensite in cold-drawn wire samples was found by differential scanning calorimetry to be in the range 1800 to 2200 J/mol in cold-drawn 304 wires, in reasonable agreement with values for the heat of formation of martensite in 4340 steel determined by a completely different method. We also observe an exothermic reaction near 650°C of a few hundred J/mol which we ascribe to the recrystallization of cold-worked austenite.

Using three antibodies to myosin head, attaching to (1) distal region and (2) proximal region of myosin head catalytic domain, and (3) to myosin head lever arm domain, respectively, we have shown definite differences between in vitro actin-myosin sliding and muscle contraction. In the present study, we studied the effect of these antibodies on the development of rigor tension and stiffness in single skinned muscle fibers at pCa>9. To form rigor actin-myosin linkages, myosin heads should override tropomyosin, covering myosin-binding sites on actin, and to detach antibodies from them. Despite their different attachment sites in myosin head, all these antibodies slowed down development of rigor tension and stiffness with or without changing their peak values. The rigor tension versus stiffness relation was highly variable, suggesting that the rigor tension reflects the sum of tension in individual rigor linkages, while rigor stiffness represents the total number of rigor linkages. Dummy antibody had no effect on the development of rigor state. These results indicate that the action of myosin heads overriding tropomyosin is inhibited by the antibodies, so that development of rigor state is slowed down due to gradual detachment of the antibodies from individual myosin heads. Highlights The effect of three antibodies, attaching to different regions in myosin heads on the development of rigor state was examined at pCa >9, using single skinned muscle fibers. Despite their different binding sites on myosin, all the antibodies slowed down development of rigor tension and stiffness with or without changes in their peak values. The rigor tension versus stiffness relation was highly variable, suggesting that rigor tension reflects the sum of tension generated by individual myosin heads, while stiffness serves as a measure of total number of rigor linkages. These results indicate that the antibodies inhibit myosin head movement to override tropomyosin, and detachment of the antibodies from myosin heads is necessary prerequisite for rigor linkage formation.

Magnetic Co₃Pt films were sputtered on a Ru(0002)/Pt(111) bilayer on glass substrate at room temperature. The effects of a Ru buffer layer thickness (t nm) on magnetic properties and microstructures were studied. AFM surface roughness results revealed that the root mean square roughness (R_rms) of the Ru/Pt bilayer surface is smaller than 1.5 nm. Granular Ru topography was observed as t is larger than 7 nm, which played an important role in influencing the magnetic properties and microstructures of Co₃Pt thin film. In this study, Ru(0002) grew along the Pt(111) underlayer and then became a template for epitaxially growing Co₃Pt(0002) film, in order to enhance the perpendicular magnetic anisotropy (PMA). Maximum H_c were obtained as t=15, due to the columnar structure formed in the whole Co₃Pt/Ru/ Pt film. It demonstrates that a Ru buffer layer is helpful to enhance the PMA of Co₃Pt magnetic thin film and increase out-of-plane squareness (S_⊥) and H_c.

This study deals with tuning magnetic properties of a thick amorphous (a-)Co₂₀Fe₆₀B₂₀ (CoFeB262) film by using interlayer magnetic coupling in trilayer structured films of [CoFeB262 (100 nm)/[Cr,Ta (x nm)]/CoFeB262 (y nm)] with y=2-50, x_Cr=0.75, 2 and x_Ta=1, 4. All the films are deposited directly on thermally oxidized Si substrate at ambient temperature using magnetron sputtering. The as-deposited a-CoFeB262 (100 nm) film exhibits magnetic stripe domain and transcritical hysteresis loop due to large effective magnetic anisotropy caused by stress induced during deposition of the films. On the other hand, the shape of magnetic hysteresis (M-H) loops in trilayer films transforms from transcritical to rectangular shaped one with enhanced remanence ratio (M_R/M_S) of ≥ 75% and single magnetization reversal behavior. This effectively reduces coercivity (H_C) and field required to saturate magnetization (H_S) in trilayer films. However, the changes in the loop shape and reductions in H_C and H_S depend strongly on x and y. Magnetic domain images obtained using Kerr microscopy in trilayer films show a rapid switching of large-sized domains along easy-axis and weak ripple domains along hard-axis. In addition, the magnetization reversal behavior along the hard-axis strongly depends on x_(Cr,Ta). M-H loops obtained at different temperatures between 30 K and 300 K reveal no change in loop shape for trilayer films with small x and y, while the disappearance of shearing and formation of additional steps at low temperatures are observed for films with large x and y. The observed results are explained on the basis of change in interlayer coupling between CoFeB262 layers with x, y and temperature. Furthermore, these results clearly confirm that the magnetic properties of thick CoFeB262 film with stripe domain can easily be tuned into in-plane magnetization by this simple trilayer structured thin films.

The mathematics of quantum physics from the standard model using groups U(1)xSU(2)xSU(3) and the Pauli principle produces two sets of time independent quantum states n(n+1) and n(n-1) where n is the principal quantum number. Oscillations between these states result in a one to one mapping with the Roberts-Janet Nuclear Periodic Table by interpretation of n>0 for condensed matter and n<0 for plasma prior to fusion. The mechanism provides a framework for Periodic Tables for every supernova by excluding mass number.
In the lower half of the table occupation by bosons leads to increased energy densities in which an ensemble of outcomes is discussed. An hypothesis of string theory is proposed at the nuclear end of the table merging into quantum loop gravity at the condensed matter at the top end of the table.

The objective of this paper is to study intensively the design of a printed slotted patch based lotus shape structure mounted on a dielectric substrate backed with an electromagnetic band Gap (EBG) layer for wideband applications. The dielectric substrate is made of a Roger RT/duroid®5880 layer. An EBG layer is introduced on the back profile of the substrate to provide a high gain bandwidth product over wide frequency bands. The antenna is fed with a novel coplanar waveguide (CPW) structure of a flared geometry; therefore, the ground plane is mounted on the same substrate surface with the patch structure. A conductive trace is introduced at the substrate back from the bottom connected to the CPW through two shoring plates to remove the effects of the EBG layer on the feed structure. The EBG performance and the antenna design methodology are discussed using analytical analyses and numerical parametric studies, respectively. The numerical simulation is conducted using CST MWS Finally; the optimal antenna design is fabricated and measured for validation to be compared to the simulated results.

Based on the full-potential linearized augmented plane waves method (FL-LAPW) with local density approximation (LDA), the partials and totals densities of state of Tl3SbS3 and SbT eI are calculated in order to find the semiconductor character via direct or indirect gap. Tl3SbS3 and SbTeI present the most important candidates of the antimony chalcogenides family. Their densities of states curves bring out characteristic features in the valence band a core like peak, at environ 13.00 eV below the valence band maximum, originating mainly from S 3s and I 5s states respectively, and a three-peak structure at the top of the valence band from S 3p and I 5p states hybridized with Sb 5p and Te 5p states. Our results give a good agreement with other theoretical calculations and experimental data.

Poly(vinylidene fluoride) (PVDF) composites have recently emerged as excellent candidates to fabricate flexible and small piezoelectric generators for portable devices. Among various techniques used to nanostructure polarized PVDF, the track-etching represents a new route for manufacturing nanostructured composite thin films. The moderate influence of irradiation on the piezoelectric response of polarized PVDF makes possible the use of this technique. In this way, a nanostructured composite based on polarized thin PVDF films comprising embedded nickel nanowires (Ni NWs) was fabricated. The nanostructured PVDF/Ni NWs composites were tested under bending conditions using a homemade pressure cell. Due to the presence of NWs, an increase of five-fold the initial dielectric permittivity, in the low-frequency range, was observed. It suggested the presence of an interfacial polarization at the PVDF/Ni interface. With respect to the etched PVDF, the nanostructured PVDF/Ni NWs composites exhibited a non-negligible enhancement by 2.5 times the piezoelectric efficiency. This result was attributed to the increased Au/Ni NWs electrode surface.

This paper concerns an eco-friendly manufacturing process for low density compressed sheet gaskets used to maintain gastight properties regarding gases and liquids. The main raw materials in a low density compressed sheet gasket are latex, organic/inorganic textile, and fillers; in this research, a sheet gasket was continuously manufactured without using organic solvents through a method called the paper making process. The results demonstrated properties such as compressibility, recovery, tensile strength, oil resistance, and high temperature leakage, properties suitable for sealing materials. The production environment also improved dramatically as organic solvents were not used during the manufacturing process, and production efficiency was increased as well.

The technologies of manufacture of medieval and modern weapons in Spain and Japan, keep a very remarkable similarity. Through different paths and sensitivities, the use of steel was achieved with a common idea: hardness, resistance and toughness; all combined in a single set of steel.