Growth and N2fixation in Saline and/or Water Stressed Sesbania aculeata Plants in Response to Silicon Application

Silicon - This study aimed at investigating the effects of silicon (Si) on dry matter yield (DM), N uptake and N2-fixation in Sesbania aculeata grown under water stress and/or salt stress using...     

Biomimetic chitosan-hydroxyapatite hybrid biocoatings for enamel remineralization

Development of biomimetic ceramic-based materials is currently a challenge in dental tissue engineering. Synthetic hybrid chitosan (CS)-hydroxyapatite (HAP) layers are regarded as candidates for teeth remineralization, protection against further demineralization ensuring also antibacterial activity. Thus, the aim of this work was to obtain new biomimetic CS-HAP layers for restoration of damaged mature enamels and to pursue morphological, compositional, structural and hardness modifications of the grown layers by immersion for 4, 7 and 10 days into artificial saliva (AS) under CS-Emdogain (EMD) hydrogel action. SEM-EDX, HRTEM-SAED, FTIR and micro-Raman findings indicated formation of carbonate-substituted HAP, B-type, with c-axis orientation in the newly formed CS-HAP coatings. Prolonged immersion span of 10 days caused increasing CS content in the superficial grown layer while carbonate content diminished. Optimum Ca/P ratio (1.85 at%) and hardness of 2.48 GPa were recorded for seven days growth using CS-EMD hydrogel. Subtle changes in HAP lattice parameters were recorded for 10-day grown layer while c-axis orientation of HAP crystals at mesoscale was preserved. Mechanism of CS interaction during in situ biomimetic synthesis and self-assembly of HAP crystals under CS-EMD hydrogel presence is also discussed.     

Effects of Power Terms and Thermodynamics on the Contraction of Pinch Radius in Plasma Focus Devices Using the Lee Model

The influence of the power terms Joule heating and radiative losses on the pinch radius in plasma focus devices is studied. Numerical experiments were carried out using the Lee model on three plasma focus devices spanning a large range of storage energy (PF400, INTI PF, PF1000) with different filling gases (N, O, Ne, Ar, Kr, Xe). Six possible regimes each characterized by a combination of significant power terms affecting plasma focus dynamics are found and discussed. These six possible regimes are further moderated by thermodynamic effects related to the specific heat ratio SHR of the plasma. In PF1000, the thermodynamic compression effects are clearly apparent in the radius ratio versus pressure curve for nitrogen which with atomic number Z_n = 7 is less radiative than neon with Z_n = 10, the dominant line radiation being proportional to Z _n ⁴ . In neon radiative compression at optimum pressure is so dominant that it masks thermodynamic compression in the compression versus pressure graph. Results show that plasma radiation losses enhance the contraction of the plasma focus pinch radius within suitable pressure ranges characteristic of each machine for each gas discussed in this paper. The radiation enhancement of compression increases with the atomic number of the gas.     

Textile applications of commercial photochromic dyes: part8. A statistical investigation of the influence of photochromic dyes on thermoplastic fibres using a UV-irradiation technique

Abstract

This research investigates the influence of the commercial photochromic dye concentration, expressed as a percentage, and polymer type and their interaction on the photocoloration properties of the as-spun and drawn fibres regarding the melt-spinning process. As-spun fibres made of polypropylene, polyethylene and polyester were spun with different percentages of the photochromic dye, drawn, tested and analysed under a factorial experimental design using appropriate experimental and statistical methods. According to the analyses and by using an independent source of ultraviolet irradiation and traditional colour measurement instrumentation of the degree of photocoloration and background colour, the most effective and significant parameter influencing the as-spun fibre’s photocoloration properties are the polymer type; the dye percentage effect was noted in the degree of photocoloration. The effects of the multi-stage hot-drawing process on the photocoloration properties of the drawn polypropylene and polyethylene fibres were characterised and statistically modelled. The dyed fibres showed reversible photochromism, developing pronounced colours from weak background colours on irradiation with ultraviolet light and returning to their original state when the ultraviolet light source was removed. The dye percentage positively affects the photocoloration of the as-spun and drawn polypropylene and polyethylene fibres. A new forecasting data source was achieved to optimise the selection of the polymer and the dye percentage and to specify the direction of increasing or decreasing of the significant process parameters. Utilising the elastic properties of manufactured fibres, they could be used in the development of chromic textiles for creative design, functional or smart purposes.     

Electrochemically prepared heterojunction of polyaniline on n-SrTiO3

A p-type polyaniline (PAn) film was electrochemically polymerized directly on an n-type strontium titanate (SrTiO₃) ceramic and thus an n-SrTiO₃/p-PAn heterojunction was fabricated. It is demonstrated experimentally that the heterojunction shows rectifying characteristics. The voltage-sensitive varistor coefficient and the ideality factor of the diode were calculated to be 3.76 and 3.68, respectively. Surface treatment of SrTiO₃ ceramics, interfacial contact of the composite and some other factors affecting the current-voltage (I-V) characteristic of the n-SrTiO₃/p-PAn heterojunction were studied.     

A novel thermal probe design for the measurement of energy influx in RF remote plasma

A novel design of a thermal probe to measure the energy influx of RF plasma has been achieved. This probe utilises one-dimensional steady-state conduction through the probe's cylindrical body and has the ability of controlling its exposed surface's temperature. The probe is fully instrumented so that the temperature field within it is known. This temperature field will serve as an indicator of achieving steady-state conduction as well as securing the needed data to calculate the energy influx of the RF plasma. Experimental results show that the plasma energy influx varied from 0.3 kW/m² to 2.2 kW/m² for RF power ranging from 15 W to 300 W, respectively. The variation of the energy influx with the RF power was found to follow a linear profile and a simple relation is proposed to model this variation for the considered plasma. Error analysis has been carried out to estimate the experimental uncertainties in the resulting energy influx values. The resulting uncertainties are found to be within the acceptable range for such applications.     

Ion density increase in high power twin-cathode magnetron system

In contrast to conventional plasma deposition methods, High Power Impulse Magnetron Sputtering (HIPIMS) utilizes extremely high power inputs in short pulses, providing for the discharge current densities up to several A/cm². High ion densities are observed not only during the plasma on-time, but also within the afterglow period. Once ions are generated, they can contribute to the peak ion density of the next pulse if the off-time between the pulses is sufficiently small. When the HIPIMS cycle contains two pulses, separated by a short plasma off-time and followed by a long afterglow period, the peak ion density for the second pulse can be 5–7 percents higher than for the first pulse. With a dual cathode system and time-shifted pulsing with distinct magnetron heads it was possible to increase ion density gain up to 40% for Ti targets.     

Fatigue and Fracture Behavior of a Ca-Based Bulk-Metallic Glass

The compression and fatigue behavior of a Ca₆₅Mg₁₅Zn₂₀ bulk-metallic glass (BMG) was studied in air at room temperature. During the preparation of cubical samples of the Ca₆₅Mg₁₅Zn₂₀ for compression and fatigue investigations, small spherical cavities were found. Under both monotonic and cyclic compression loadings of the samples, fractures initiated at these cavities and propagated in a direction generally parallel to the loading axis. Finite-element analysis (FEA) was used to model the fracture behavior. The FEA of a centrally located spherical void showed that under compression loading, large tensile stresses evolved in the cavities. The orientation of the maximum principal stress (P1) was found to be normal to the direction of crack propagation, which is consistent with the experimental finding. Stresses in deeply embedded adjacent voids and those in superficial voids were also studied. The influence of the void location in the cubical sample on the fracture behavior was quantitatively discussed.     

Thermal–hydraulics features of the use of LEU U3Si2 fuel in low-power reactors

Calculations for the use of the U₃Si₂ LEU fuel in low-power research reactors were made. The design basis accident was simulated using the feedback coefficients calculated by the BMAC system. Usability of this fuel in low-power research reactors was demonstrated for both normal daily and accidental operation conditions even if the power of the reactor touches 142 kW during the design basis accident simulation. Both HEU and LEU fuels behave similarly in the normal operation, the temperature of the cladding reaching about 60 °C while higher temperature are obtained for the accidental conditions in the case of the LEU fuel (about 113.7 °C against 98.6 °C for the fuel center temperatures).