Results in Materials最新文献

Optimization of process parameters for photocatalytic activity measurement of CuO nanoparticles (NPs) was the focus of this study. CuO NPs were prepared following chemical co-precipitation method and characterized using X-ray diffraction (XRD), ultraviolet visible (UV–vis) spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) and Fourier transform infrared spectroscopy (FTIR). Subsequent studies concentrated on optimizing pH of Rhodamine B (Rh B) dye, catalyst doses, and concentration of hydrogen peroxide (H₂O₂) for effective photocatalytic degradation. This optimization process was intended to properly investigate the photocatalytic activity of CuO NPs using Rh B dye (5 ppm), a frequently encountered organic pollutant. After 180 min of UV irradiation at optimized condition (pH 10, 0.3125 mg/mL NPs, 9000 ppm H₂O₂) a degradation rate of 60 percent was recorded. These findings maximized the degradation efficiency of CuO NPs to exploit as a potential photocatalyst.

This work reports the structural, thermal, optical and electrical properties of PEMA, PVC and their polyblends. These properties are investigated by FTIR, TGA, UV/Vis and broadband dielectric spectroscopy. FTIR spectra showed that the characteristic bands of PEMA and PVC are affected by blending and displayed red and blue shifts confirming that an intermolecular interaction between PEMA and PVC is occurred. Thermal degradation kinetics of PEMA, PVC and its polyblend samples is investigated in details and the thermal properties of each decomposition stage are estimated. UV measurements analysis revealed that Urbach energy (E_U) is increased while optical bandgap decreased upon increasing the PVC content. The indirect and direct band gap (E_ig/E_dg) values are decreased from (3.95/4.21) to (3.10/3.92) eV. Also, upon increasing the content of PVC, the lattice dielectric constant (ε_L) is increased from 2.71 to 7.83. Wemple-DiDomenico model is applied for investigating the refractive index dispersion and to calculate the oscillator and dispersion energies. It is observed that the linear/nonlinear parameters are increased nonlinearly with increasing the PVC content. χ⁽¹⁾, χ⁽³⁾ and n₂ values are found to increase from 0.104, 0.213 × 10⁻¹³ and 4.01 × 10⁻¹² to 0.363, 31.26 × 10⁻¹³ and 5.33 × 10⁻¹². These results make PEMA/PVC polyblend strong candidates for use in the development and design of advanced optoelectronic devices. AC conductivity (σ_ac) and dielectric measurements are carried out at various temperatures in wide frequency range. Jonscher power law is applied and showed that the predominant conduction mechanism in our samples is overlapping large-polaron tunneling (OLPT). The dielectric constant and electrical impedance are found to be frequency and temperature dependent. The investigation of the electric modulus (M*) revealed that M′ is increased non-linearly with increasing the frequency, while M″ spectra displayed two different modes of relaxation. The interfacial polarization (IP) is observed in low frequency region, while, dipolar relaxation is detected in high frequency region.

In this research, a combination of hybrid and non-hybrid composite materials were tested for their mechanical properties and water absorption rates. The study focused on composites produced through hand-layup techniques, examining their void percentage, morphology, and elemental composition. Specifically, three different stacking sequences of hybrid composites were compared with three non-hybrid composites of equal thickness. Combining carbon and glass allows the composites to balance flexural (367 MPa, 23 GPa) and tensile (440 MPa, 5.7 GPa) strength and modulus, all while remaining cost-effective and easily accessible. The glass fiber-based composites exhibited exceptional impact (27 J/cm²) strength due to their interfacial solid bonding. Additionally, the study found that basalt and carbon-basalt composites had varying degrees of water absorption when exposed to seawater and river water. SEM and EDS Mapping analyses were conducted to understand better fibrous and granular composites' mechanical properties and water absorption behaviors. These analyses provided valuable insights and a comprehensive knowledge of composite properties. Ultimately, the study recommends using hybrid composite materials for specific applications based on desired flexural tensile strength, impact strength, or water absorption characteristics.

Adhesive bonded joints hold significant importance across various industrial sectors in modern engineering, owing to their lightweight nature and myriad advantages. The rising demand for trimaterial joints underscores their utility and versatility. In these joints, the choice of materials for both adherends greatly influences their strength, structural reliability, and overall characteristics. While numerous researches have extensively analyzed stress distributions, their effects, and behaviors, many have relied on a one-factor-at-a-time approach, focusing solely on individual design variables' effects. However, recognizing the intricate interplay among various material combinations and their collective impact on overall performance, this study employs various types of White-box, Black-box, and Grey-box machine learning algorithms to identify an optimized ML model as well as predict stress distributions for any random combinations of upper and lower adherend materials. Dataset of total 178 random material combinations were utilized for the training phases with 5-fold cross validation and model tuning. However, the decision tree regressor emerged as the optimized model by comparing the quantitative metrics of accuracy benchmark as well as the prediction outcomes obtained through all the machine learning models. The maximum prediction accuracy attained was an impressive 99.97 %, while the minimum recorded was 89.74 %. This research aims to identify tailored machine learning model specifically for trimaterial bonded joints where nano layer of resin is utilized as the adhesive.

The liquid breeding blanket concept of a fusion reactor is based on the employment of the eutectic Lead-Lithium solution (LLE), where Lithium, enriched in ⁶Li, has the purpose of regenerating Tritium by reacting with neutrons, while Lead enhances the process acting as neutrons multiplier. Anyway, despite the huge interest on this binary system, LLE is not characterized yet by a fully consolidated description of its basic thermophysical properties and, in many cases, the spread of values reported so far in literature remains still significant. The purpose of this paper is hence to check again the many data available in literature, with a special attention to the ones more recently published, trying to explain and solve their inhomogeneity. Taking into account the general features of the Pb-Li interaction and particularly the not ideal behaviour of the Pb-Li liquid solutions, the following thermophysical properties of the LLE are dealt in detail: specific heat; density and volumetric thermal expansion coefficient; thermal conductivity and diffusivity; electrical resistivity; Sieverts' constant of Hydrogen. Based on the deep analysis of all the reported experimentation and through the adoption of several comparison criteria, the most trustable correlation is sought for each of the above properties; additionally, when a robust correlation couldn't be retrieved, a new, optimized, one has been proposed, capable also to foresee correctly the effect of small composition variations and to assure the internal coherence among linked properties.

Specific heat and density values resulted at the end accurately described and not needing for additional experimentation; thermal properties and electrical resistivity can be evaluated with decent confidence, even if their uncertainty could be somehow reduced by future investigations; for Sieverts' constant it has not possible yet to identify a unique, trustable correlation, anyway the range of values correctly assumed up to 900K has been significantly restricted.

Magnetic fluid hyperthermia (MFH) is one of the new methods for personalizing cancer treatment. In this study, ${20\text{SiO}}_2‐50\text{FeO}‐15\text{CaO}‐15{\text{Na}}_{2}O$ glass ceramics was selected as the base glass and the effect of adding different $P_2{O}_5$ percentages on the magnetic properties and bioactivity of the samples were investigated. Phase studies showed that maghemite, hematite, sodium calcium silicate, and iron calcium silicate phases have crystallized in glass ceramics. Structural studies showed that $P_2{O}_5$ acted as a nucleation agent in glass ceramics and reduced the size of maghemite and hematite crystals. By increasing $P_2{O}_5$ to 2 wt%, the magnetic saturation of the samples increased to 22.5emu/g and decreased in higher percentages. The highest increase in temperature also belonged to these samples, and its value was measured as 13 $°C$. Study the samples immersed in the simulated body fluid (SBF), it was seen that hydroxyapatite with cauliflower morphology was crystallized on the surface of the samples.

The generation of waste from the demolition of old structures poses a significant environmental challenge. Recycling these materials as aggregates in concrete offers a potential alleviation of environmental impact. While recycled aggregates offer promise as a remedy, they are not without drawbacks. However, innovative approaches have been developed to overcome these limitations. Among these, plastic coating stands out as a particularly sustainable solution. This study investigates the influence of plastic coating temperature on recycled concrete brick aggregates (RCBA), which serve as coarse aggregates. The RCBA were coated with locally sourced polyethylene terephthalate (PET) at varying temperatures, such as 250 °C, 300 °C, 350 °C, and 400 °C. Then the physical properties of the plastic-coated recycled aggregates (PCRA) were assessed. Additionally, concrete specimens incorporating PCRA were fabricated to evaluate their influence on the mechanical properties of concrete. The results indicate that higher coating temperatures positively influenced the physical properties of the aggregate. Furthermore, at elevated temperatures, the plastic became sufficiently malleable to penetrate deeper into the permeable pores, reinforcing the weak mortar interface and thereby enhancing the mechanical properties of the concrete made with it. Additionally, mathematical models have been proposed to predict the influence of plastic coating temperature on both the physical properties of the RCBA and the mechanical properties of the concrete.

This study investigates and compared various properties of high-quality foundry sands on the surface quality of castings, whose cores are produced using the col-box method. Methods such as the measurement of flushable fraction, sieve analysis, electron and optical microscopy, pH and electrical conductivity measurements were used to monitor the physico-chemical properties of silica and non-silica sands. 5 core mixtures were prepared from individual sands by adding 1.6 % of organic binder based on phenol-formaldehyde formed from resin and hardener using an MR100 mixer. The produced cores were placed in moulds made of a uniform bentonite mixture and cast (15 test castings). In all the tested sand samples, the dust content was visible at a 300× magnification, but the share of flushable content is not exceeded 3 %, which is one of the fundamental conditions for moulding. All the tested sands are heat resistant at 1600 °C and had a low flushable fraction in the range 0.05–0.3 %. The results indicate that the occurrence of surface defects in high-quality foundry sands is not related to the flushable fraction content, to the average grain size value d₅₀, to the electrical conductivity, to the shape of the sand grains and to the flexural strength. The surface roughness is related to the average grain size, to the grain shape and to the flexural strength.