High-temperature hydrogen production by solar thermochemical reactors,metal interfaces,and nanofluid cooling

Journal of Thermal Analysis and Calorimetry - Solar thermochemical reactors have been considered in recent studies because of converting the solar energy to a fuel, which is called solar fuel. In...     

Sol–gel synthesis and characterization of unexpected rod-like crystal fibers based on SiO2–(1-x)CaO–xSrO–P2O5 dried-gel

Sol–gel technique has several benefits for the preparation of glass, and morphology can be better controlled compared to conventional methods. In this research, new sol–gel derived bioactive glasses based on SiO₂–CaO–SrO–P₂O₅ dried-gel were synthesized and characterized. Herein, a series of 58S bioactive glasses with the composition of 60%SiO₂–36%(CaO/SrO)–4%P₂O₅ (mol%) were synthesized, and the effect of adding strontium (Sr) to the glass structure SiO₂–(1-x)CaO–xSrO–P₂O₅ (where x = 0, 0.5, 0.1, 0.25, 0.5 and 1) was investigated by gradually substitution of Sr with calcium (Ca). The obtained results indicated that the Sr free sample totally takes amorphous state indicative of the internal disorder, glassy nature and non-crystalline states of this material. Surprisingly, after further addition of Sr to the glass structure, the X-ray diffraction (XRD) patterns and scanning electron microscopy (SEM) micrographs showed unexpected significant rod-like crystal fibers, and the major diffraction peaks of Sr(NO₃)₂, SrCO₃ and Sr₂Si₂O₄ became sharper and more apparent up to the final addition of Sr. The complicated and contradictory results underscore the need for better knowledge of how impurities act upon by growing rod-like crystals. In addition, totally understanding the effect of Sr on the morphology of samples from the bottom up is a daunting challenge.     

Connectionist intelligent model estimates of convective heat transfer coefficient of nanofluids in circular cross-sectional channels

Journal of Thermal Analysis and Calorimetry - The effect of Na2CO3 additive on the steam gasification characteristics of Sunjiahao (SJH) coal char was studied in the present paper. Na2CO3-catalyzed...     

Optimal design and analysis of a district energy system including heat and power production for domestic applications and fuel for vehicles

Journal of Thermal Analysis and Calorimetry - Residential sector has a great share in the global energy demand. As the use of renewable energy sources increases, energy supply of the residential...     

Characterization of the physical–mechanical properties of dental resin composites reinforced with novel micro-nano hybrid silica particles: An optimization study

Abstract

In the study, dental composites of color A2 using Bis-GMA/UDMA/TEGDMA resins (ratios 70/10/20), and silica filler (70%wt, 75%wt, and 80%wt) which is a hybrid of two silica types in nano and micro dimensions were made using two different photoinitiators namely BAPO and camphorquinone. The optimum photoinitiator was selected based on the mechanical tests results after which the composites were subjected to the following tests: FTIR to evaluate polymerization degree, microhardness test, UTM, and SEM micrographs were taken to analyze the surface fracture of samples. The results of photoinitiator selection (flexural strength test) is 36.54?MPa, 37.62?MPa, and 75.08?MPa for BAPO?+?camphorquinone, camphorquinone, and BAPO respectively. The results show that the BAPO photoinitiator exhibits better results over camphorquinone and also BAPO/camphorquinone initiator systems. Then after choosing the photoinitiator system composites with different filler contents show higher mechanical strength than existing dental composites. The results of the mechanical tests for the composites with different filler contents synthesized after initiator system selection were significantly higher than the values specified in ISO 4049:2009 (102?MPa over 80?MPa). FTIR results indicate that the degree of conversion in these composite is 25.41%, 37.68, and 40.94% for composites with different filler amounts.     

Enzymatic Treatment and Detoxification of Acid Orange 7 from Textile Wastewater

A crude preparation of horseradish roots was used as a low-purity source of horseradish peroxidase (HRP) in dye decolorization experiments. The technical feasibility of the process was studied in bench scale for enzymatic removal of acid orange 7 (AO7), a synthetic dye. Further studies were carried out to understand the effects of process parameters such as pH value, H(2)O(2) level, concentrations of the synthetic dye, and HRP during enzyme-mediated dye degradation. Experimental data revealed that the concentration of AO7, pH of the aqueous phase, amount of the enzyme, and H(2)O(2) level played significant roles on the overall enzymatic reaction. Polyethylene glycol, as an anti-inactivation of HRP, in various concentrations showed no significant effect on the decolorization. The experimental data of initial reaction rates were fitted using an analytical equation proposed by Michaelis-Menten. The acute toxicity tests using Daphnia magna exhibited that the enzymatic treatment significantly decreased the toxicity of the dye solution.     

Heterogeneous shear in hard sphere glasses

There is growing evidence that the flow of driven amorphous solids is not homogeneous, even if the macroscopic stress is constant across the system. Via event-driven molecular dynamics simulations of a hard sphere glass, we provide the first direct evidence for a correlation between the fluctuations of the local volume fraction and the fluctuations of the local shear rate. Higher shear rates do preferentially occur at regions of lower density and vice versa. The temporal behavior of fluctuations is governed by a characteristic time scale, which, when measured in units of strain, is independent of shear rate in the investigated range. Interestingly, the correlation volume is also roughly constant for the same range of shear rates. A possible connection between these two observations is discussed.     

Photoluminescence in the characterization and early detection of biomimetic bone-like apatite formation on the surface of alkaline-treated titanium implant: state of the art

Photoluminescence (PL) property is particularly important in the characterization of materials that contain significant proportions of noncrystalline components, multiple phases, or low concentrations of mineral phases. In this research, the ability of biomimetic bone-like apatite deposition on the surface of titanium alloy (Ti6Al4V) substrates in simulated body fluid (SBF) right after alkaline-treatment and subsequent heat-treatment was studied by the inherent luminescence properties of apatite. For this purpose, the metallic substrates were treated in 5 M NaOH solution at 60 °C. Subsequently, the substrates were heat-treated at 600 °C for 1 h for consolidation of the sodium titanate hydrogel layer. Then, they were soaked in SBF for different periods of time. Finally, the possibility to use of PL monitoring as an effective method and early detection tool is discussed. According to the obtained results, it was concluded that the PL emission peak did not have any significant shift to the shorter or higher wavelengths, and the PL intensity increased as the exposure time increased. This research proved that the observed inherent PL of the newly formed apatite coatings might be of specific interest for histological probing and bone remodelling monitoring.