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...     

Effects of dopant concentrations on phosphorescence properties of Eu/Dy-doped Sr3MgSi2O8

Long afterglow Sr₃MgSi₂O₈: Eu, Dy phosphor with high brightness was prepared by sintering at high temperature and weak reductive atmosphere. The luminescent properties of this photoluminescent pigment were studied systematically by investigating concentration effects. The analytical results indicated that the main emission peaks appear at 482 nm. The excitation and emission spectra of this phosphor show that both of them are broadband. This is ascribed to the 4f⁷→4f⁶5d¹ transition of Eu²⁺ in the pigment matrix, which is in good agreement with the calculated value of 470 nm, and implies that luminescent centers Eu²⁺ occupy the deca-coordinated Sr²⁺ sites with the host of Sr₃MgSi₂O₈.     

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.     

Surface modification of poly(lactide-co-glycolide) nanoparticles by d-α-tocopheryl polyethylene glycol 1000 succinate as potential carrier for the delivery of drugs to the brain

The potential health benefits of vitamin E (d-α-tocopheryl polyethylene glycol 1000 succinate, TPGS), particularly, in curing of the neurological symptoms associated with vitamin E deficiency have been reported. Hence, vitamin E containing carriers for delivery of drugs to the brain might be useful from different points of view. Herein, in order to obtain desired surface morphology and particle size of poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) and high emulsifying effects, TPGS-modified PLGA NPs were optimized as a potential carrier for the delivery of drugs to the brain. The particle sizes, surface morphology, phase composition correlated with different emulsifiers and different stirring times were characterized. Also, the in vitro cytotoxicity of the samples using PC12 cell line was investigated. According to the obtained results, by increasing the percentages of TPGS, the average particle size decreased and the distribution of particle diameters came closer by further addition, and the larger particles did not create. In addition, no obvious cytotoxicity was observed at various TPGS amounts, and the modified PLGA NPs were considered biocompatible since they show little decrease in cellular viability. With the increase of TPGS ratio, more effective in vitro therapeutic effects could be observed, which achieved the highest cell viability, because the degradation of NPs may release the most amounts of TPGS components that have synergistic activity. Furthermore, it was found that TPGS as a water-soluble derivative of natural source of vitamin E could be a perfect emulsifier for making PLGA NPs as potential carrier for delivery of drugs to the brain.