Zeitschrift für Materialwissenschaften und Ingenieurwesen

Auxetic materials are materials that expand in the transverse direction when stretched longitudinally, giving them some unique properties in comparison to conventional materials. In textiles, both auxetic and non-auxetic yarns can be used to weave auxetic fabrics. This article demonstrates the modeling of a double arrow auxetic geometry for estimation of Poisson’s ratio and subsequent development of a woven construction to examine the potential of this geometry to produce an auxetic fabric. The fabric structure is modified to incorporate the double arrow auxetic geometry using a combination of loose and tight weaves, as well as elastic and inelastic yarns. The fabric structure is modeled semi-empirically. To determine the effect of yarn elasticity on the auxeticity of the fabric structure, three different counts of cotton spandex yarns were used. It was observed that when the different weft counts were used, the coarser weft count exhibited NPR over a wide strain range. The semi-empirical model of double arrow geometry fits the experimental data well.

Automation and artificial intelligence have improved product accuracy, quality, and processing time during the previous couple of decades due to huge advancements in robotics technology. The shortage of energy supplies for global demand is currently the most critical aspect in the modern world. Electrification is a clear propensity to improve the performance and sustainability of the transportation system due to environmental concerns and regulatory pressures. Robots provide significant benefits in a wide range of applications. The introduction of robots into industrial environments and other applications leads in a significant increase in efficiency and productivity. Solar photovoltaic technology is a key research topic for converting solar energy into usable electricity. Solar robots use electrical energy stored in batteries to power their mechanical, electrical, and electronic equipment, which execute a variety of activities for both industrial and commercial purposes. Robots can function in dangerous environments for extended periods without human assistance and with excellent precision.

Flax fiber (Linum usitatissimum L) is the natural fiber which is good in mechanical properties such as impact resistance with specific strength. Now days, natural fibers are used in various field such as aircraft industries, automobile industries and textile industries. Due to low specific weight having comparable good mechanical properties these fibers is used in these industries. Flax fiber behavior changes with the hydro and thermal conditions due to hydrophilic nature. This paper is review about change in mechanical properties due to temperature and water absorption. Dynamic Mechanical Analysis (DMA) was performed to study the evolution of the glass transition temperature in function of the water uptake for composite samples immersed in distilled water at 30°C. Flax fiber have better fatigue resistance than other natural fiber. Flax fiber stiffness evolution is found that elastic modulus may increase or decrease over fatigue life in the fiber-direction.

CuInTe₂ (CIT) layers have been electrodeposited onto CdS coated FTO substrates at deposition potential -0.8 V verses Ag/AgCl reference electrode. The samples were annealed at four different temperatures viz, 350°C, 400°C, 450°C and 500°C for 20 minutes in air ambient, controlled argon ambient and Rapid Thermal Processesing (RTP) in presence of argon ambient for 5 shots. Samples were characterized by various characterization techniques to study structural, microstructural, morphological, compositional, chemical properties and concentration gradient of ionic species. Highly crystalline samples were obtained upon annealing the CIT layers in controlled argon ambient in tube furnace and RTP as a counter part of air annealed samples. Raman data shows removal of tensile strain upon annealing the samples in controlled argon ambient. Scanning Electron Microscopy (SEM) images shows increase in grain size for samples annealed at 350°C and 400°C in controlled argon atmosphere and in RTP. The high resolution Field Emission Scanning Electron Microscopy (FESEM) images shows further improvement in grain size in controlled argon atmosphere. Atomic Force Microscopy (AFM) images show rod like columnar morphology. XPS study shows the presence of Cu⁺, In³⁺, Te^2- and Te⁴⁺ states of copper, indium and tellurium. Time of Flight Secondary Ion Mass Spectroscopy (ToF SIMS) data shows almost uniform concentration of In and Te throughout the CIT layers annealed in controlled argon atmosphere. ToF SIMS data gives unique insight of concentration gradient of individual ionic species throughout the CIT layers and at CdS/CIT interface.

The early detection of aggressive forms of ovarian cancer before they metastasize is critical for reducing overall mortality from the disease. Super Paramagnetic Relaxometry (SPMR) is an imaging technique useful for visualizing early stage tumors with high sensitivity and specificity. It uses Superconducting Quantum Interference Devices (SQUIDs) to detect targeted Superparamagnetic Iron Oxide Nanoparticles (SPIONs) that visualize tumors ten times smaller than what conventional imaging techniques can. However, the ultra-sensitivity of SQUIDs increases their risk of distortion due to far-field artifacts. Therefore, a preprocessing filter was developed to mitigate far-field, low-frequency disturbances to SQUID signal acquisition. This is based on the hypothesis that correcting SQUID signal acquisition using a magnetometer for far-field detection will increase the accuracy of SPMR for early tumor detection. The hypothesis was tested in three steps. First, it was shown that the Magnetometer (MAG) could specifically detect far-field noise and effectively avoid Nanoparticle (NP) signatures. Second, low-frequency noise was induced to show that far-field artifacts in the MAG signal correlated with distortions in the SQUID channels. Therefore, a preprocessing filter was developed to parse through and parameterize MAG signal extrema to SQUID signal distortions. A series of further optimization steps included anchoring the MAG signal to respective channels, modelling and subtracting the component of structural (environmental) relaxation and constraining a general subtraction window. Third, success was measured by the image reconstruction accuracy of sources with various NP concentrations, using the HSPMR dipole-fitting technique. Overall, the MAG-filter increased reconstruction accuracy more effectively with decreasing NP signal; accuracy increased the most at very low concentrations (~ 1ug). This preliminary data indicate that the filter increases SPMR sensitivity for low NP concentrations representative of small cell clusters, typical of early disease stages. Future work will optimize this initial filter to work uniformly and effectively across different NP concentrations (and tumor sizes) and translate this technology to highly sensitive early tumor detection.

High density nickel-aluminium bronze alloy (Cu₉Al₄Fe₃Ni) was manufactured using Laser Powder-Bed Fusion Technique (L-PBF), it was investigated regarding the effect of different heat treatment conditions on its mechanical, microstructural and tribological behaviour. Correlations between the microstructures generated (k phases) and the behaviour observed were established. Regardless the heat treatment applied (annealing, tempering, quenching and tempering), friction coefficient, wear loss and hardness have been shown to decrease with increasing heat treatment temperature, while tensile strength and the elongation improved compared to the as-built sample. On the other hand, correlations using increased precipitates content resulting from different heat treatments confirmed the improvement of the material’s mechanical properties at the expense of the tribological ones. A possible interpretation of this results maybe the role of precipitates in impeding dislocations motion leading to increased shear forces, thus deteriorating the embeddability of the soft α phase along with detachment of the hard κ phases allowing a three body abrasive wear to occur. However, in a process similar to strain hardening, hardness and tensile strength are shown to improve with increased precipitation.

Dielectric properties of (Ba_0.4Ca_0.6) Ti₄O₉ ceramic material prepared by mixed oxide solid state route were studied. X-Ray Diffraction (XRD) showed that the calcined powder of (Ba_0.4Ca_0.6) Ti₄O₉ at 900°C crystalizes in the phase of complex peroveskite type. Dielectric properties measurement was carried out by LCR meter at the range of (1 MHz to 100 MHz) and (1 GHz to 2 GHz) frequencies. The εr value of (Ba _0.4 Ca_0.6 )Ti₄O₉ sintered ceramic sample increased with increasing frequency. In the present work, a controlled mixed oxide solid state processing route was used to prepared microwave dielectric material (Ba_0.4Ca_0.6) Ti₄O₉ and microwave dielectric properties were measured at relatively lower and higher frequencies.

The Electrodynamic Screen (EDS) is a self cleaning surface technology that can be retrofitted or integrated onto the optical surface of solar collectors, which when activated, can charge dust and remove it off the surface without using water or robotic parts. The EDS film’s electrodes enable the cleaning action and hence have to account for both conductivity and transparency to be included in the solar collectors. We present the different materials explored to serve this purpose, the reason for their selection, pros and cons of each material and results obtained upon testing their environmental durability and viability. The results from standardized accelerated weathering tests which validate the outdoor durability of the final electrode materials are also reported.

Tubular hydroforming, the process which uses high pressure to form desired complex shape quickly and easily is the future of automotive industry and is quickly becoming a worthy challenger to the conventional metal stamping and welding. The growing demand for light weight parts in the various fields like automotive, aircraft and aerospace industries have increased the scope for tubular hydroforming in the last few years. The primary advantages of the process are improvement in structural stiffness and crash behavior due to lack of welds and reduced cost assembly.

Hydroforming application demands a clear understanding of material process property relationships. Design, material selection, manufacturing and processing of tubes for this particular application remains critical. Proper understanding of material properties and its forming behavior is the basic necessity for material selection. The effect of material properties on hydroforming process of tubes was investigated. Experimental and FEA studies on free expansion of tubes have been carried out in different materials and materials were ranked based on the suitability for hydroforming. The effect of strain rate on formability of steel sheets was discussed.

A semi-empirical equation has been derived that describes the dependence of the shear stress on the shear rate during the flow of a onecomponent suspension. The suspension is considered as consisting of three fractions: single grains, their dimers and trimmers, between which equilibrium is established, depending on the shear rate. The equation is based on Krieger's formula generalized to the case of multicomponent suspensions. The derived equation well approximates the experimental data, including systems for which pseudoplastic behavior is replaced by dilatant behavior and vice versa.

Metastable β titanium alloys with twinning and/or martensite transformation have been exploited as biomedical and structural materials owing to their biocompatibility and excellent comprehensive mechanical properties. The dispersed ω phase is an important precipitation strengthening phase, which plays an important role in improving the strength of titanium alloys and assisting the transformation of α-phase. Therefore, the research of ω phase transitions in titanium alloys has become one of the hot topics for decades. In this work, the latest related research reports are reviewed, including ω phase transition mechanism, classification, and model evolution. The advantages and disadvantages of related models are compared and finally, some scientific issues are put forward.

For circulating molten lead in compact in-pile and ex-pile test loops at 773.15 K this work developed a multi-physics methodology to optimize the designs of miniature axial-centrifugal flow pumps with impeller blades diameters of 55.0, 60.0 and 66.8 mm for maximizing the pumping power, the pump efficiency, and the pressure head. Increasing the diameter of the optimized impeller blades and/or the shaft rotation speed from 1,500 to 3,000 RPM increases the pump characteristics and efficiency, but also increases the dissipated thermal power. The molten lead flow rate at the peak efficiency increases with increased impeller shaft rotation speed and /or the blades outer diameter. The performed CFD analysis shows that rounding the tips of the blades and/or decreasing their clearance from 1.5 to 2.0 mm limit the formation of the flow vortices and the pressure losses and increases the pump efficiency. Results also show that increasing the molten lead temperature from 673.15 to 873.13 K slightly decreases the pump pressure head and negligibly affects the pump efficiency. This work successfully demonstrated the use of additive manufacturing of an impeller design with 60.0 mm diameter blades.

Organizations have been thrust into a VUCA1 world as an outcome of the global COVID-19 pandemic challenges. VUCA is a worldview that is founded upon environments that are volatile, uncertain, complex and ambiguous (VUCA). Having the ability to be fast, agile and adaptable are the core competencies for VUCA survival, thus making innovation a critical success factor in business sustainability in this new world we are challenged with. Despite this value proposition argument the age-old question of “how can we effectively measure innovation impact?” within a company still exists.

Methodology: This common dilemma presents an opportunity to further critique what innovation metrics and assumptions are more relevant in a new environment such as the VUCA world? Through surveying workforce professionals confirmed that the workforce at large, are also searching for more compelling and systematic metrics that can create and sustain innovation within organizations. In addition to compiling eight years of research that systematically evaluates innovation as it relates to four organizational dimensions (Governance, Culture, Process and Design) in the VUCA world. This real-world case study based on longitudinal actionbased research (N=3567) analyzes how investing and sustaining intellectual human capital through critical systems thinking, mentor-matching and ecosystem development is critical for successful design, development and deployment of innovation within organizations.

Outcome: The outcome of this longitudinal case study is the construction of a meta-framework and algorithm. In applying the combined methodologies of Total Systems Intervention (TSI) through the organizational dimensions of culture and design (soft systems), process and governance (hard systems); a factor analysis algorithm was developed so that organizations can also apply this systematic methodology to position innovation as a business driver and strategic imperative. Therefore, such research outcomes have contributed towards the development of an integrated meta-framework and proposed metric the maturity innovation ecosystem conceptual algorithm which is the business application of GIDE.

Conclusion: Furthermore, an action plan based upon validation research, machine learning simulations and industry case studies is the logical progression of this research work. The objective is to further investigate how GIDE provides a significant knowledge and business contribution for organizations, small-medium enterprises (SME) and startups collectively.

Ln₂O₃ doped PbO-NaF-B₂O₃ glasses were prepared and characterized through spectroscopic technique such as photoluminescence at room temperature to derive luminescence properties of Ln3+ ions in these glasses. Radiative properties which include radiative transition possibilities, branching ratios, radiative lifetime and stimulated emission cross sections of the fluorescent degree of Ln3+ ions in titled glasses are determined. In the present work all our systematic analysis has been presented with an example of results obtained in PbO-NaF-B₂O₃-Ln₂O₃ glasses. These results are used to access the gain media and in turn useful not only to write waveguides but also to modify the fluorescence properties through laser irradiation.

Magnesium-based biomaterials might provide an innovative therapeutic potential to substantially enhance regeneration of dental tissues. In previous work, magnesium oxide (MgO) has been studied for its potential ability to enhance cell attachment, proliferation rate and dentin matrix protein expression of human dental pulp cells (HDPCs). However, to date, dentinogenic effect of magnesium chloride (MgCl₂) on cell viability and expression of extracellular matrix proteins in HDPCs has not been investigated. This study was designed to compare the stimulatory effect of different concentrations of MgCl₂ on dentinogenesis of HDPCs. HDPCs were cultured with 0.5 mM, 1 mM, 2 mM, 4 mM, 8 mM concentrations of supplemental MgCl₂, 0 mM as negative control group. Stimulatory effect of MgCl₂ was assessed by evaluating cell viability, and expression of dentin matrix proteins: dentin sialoprotein (DSP), dentin matrix protein1 (DMP-1), dentin sialophosphoprotein (DSPP) and type I collagen (COL-I). Statistical analysis was carried by Multi-Way Analysis of Variance (ANOVA) with Wilks’ lambda test. Supplemental MgCl₂ concentration groups between 0.5 mM - 4 mM elicited a significantly higher expression of DSP and DMP-1, while 0.5 mM - 2 mM supplemental MgCl₂ concentrations showed highest stimulatory effect on cell viability and, expression of DSPP, and COL-I, compared to the negative control group at all-time points (P<0.0001). However, 8 mM MgCl₂ group had an inhibitory effect on HDPCs with significant lower cell viability and expression levels of DSP, DMP-1, DSPP, and COL-I compared to the control (P<0.0001). In conclusion, optimal (0.5 mM-2 mM) supplemental MgCl₂ concentration groups significantly upregulated odontogenic differentiation with enhanced expression of dentin matrix proteins. This is the first study to reveal the dentinogenic effect of MgCl₂ on dentin matrix protein expression in HDPCs. Magnesium-containing biomaterials may serve as a potential material for pulp repair and dentin regeneration.

By comparing the differences between high-entropy alloys and traditional alloys, this paper highlights the outstanding advantages of highentropy alloys in modern 3D printing, and introduces the characteristics, defects and corresponding solutions of different types of 3D printing technologies. DED uses a laser, electron beam, or arc to melt the powder or wire form during deposition. SLM is to melt metal powder on a powder bed and use high-energy lasers to print geometrically complex products. EBM uses electron beam to melt metal powder. In addition, the constituent elements, processing conditions and working temperature are also important factors in determining the mechanical properties of high-entropy alloys. By adding or reducing elements and conducting some treatment, the properties of high-entropy alloys such as tensile strength, compressive properties, fracture strength and plastic strain can be found changed.

Silver nano dots are new and smart materials for application in medical field. Their sizes are in the range of <=10 nm and have unique structural, chemical, physical properties which help in molecular diagnostics, in therapies, in devices used in medical procedures. In this report we present the chemical process in which the silver nano dots are synthesized using a simple ingredient fructose as reducing which is a less expensive and is a rapid phase method. It is a very feasible method to harvest silver nano dots in the lab at a very rapid pace than the conventional methods and without toxic side effects. The size of the silver nano dots were found to match the size of biological molecules and exhibited unique properties which can find a wide array of applications in the field of medicine and industrial electronics. UVVIS study, XRD analysis, FTIR studies and TEM analysis was done to establish the fact that silver nano dots can be synthesized using simple chemical sugar like fructose. Based on the size of the silver nano dots created in the lab and their ability to penetrate the blood brain barrier in the human system they can be applied for diagnostic and therapeutic purposes.