Thermodynamic analysis of waste heat recovery from hybrid system of proton exchange membrane fuel cell and vapor compression refrigeration cycle by recuperative organic Rankine cycle

Journal of Thermal Analysis and Calorimetry - According to day-by-day consumption increase, energy high costs and nonrenewable energy destroying effects, clean technologies such as fuel cells lead...     

Numerical simulation of a three-layer porous heat exchanger considering lattice Boltzmann method simulation of fluid flow

Journal of Thermal Analysis and Calorimetry - The present study investigates the thermal characteristics of a proposed porous heat exchanger (PHE). This heat exchanger consists of three sections,...     

Species-Related Difference to Noise Reduction Between Trees in Urban Forest: The Abidar Forest Park (Case Study)

Sound pollution is one of the most important urban problems whichendangers mental and physical health of the residents. This study was aimed toassess the influence of different tree species, including Fraxinus rotundifolia,Robinia pseudoacacia, Platanus orientalis, Platycladus orientalis, and Pinuseldarica, in reducing noise pollution in the Abidar Forest Park. A further objective was to identify the contaminated areas of Sanandaj city and to propose suitable noise absorbent tree species in consistent conditions. For each tree standsthe noise measurements were performed during intervals at frequencies of 250,500 and 1000 Hz, besides an open area with the same topography. With regardsto the second purpose, a total of 50 stations with residential, commercial, residentialcommercial, and green space applications were selected across the city. EquivalentContinuous Sound Pressure Level (Leq) was determined in five replicates for 30min. The measurements were performed under stable weather conditions and lowwind velocity at 17:00 (traffic peak) in summer and fall. All of the Leq values wereabove the threshold noise level. The highest noise reduction was recorded in summer(i.e., green season); Platanus and Platycladus species demonstrated the highest andlowest noise absorption (31.43 dB and 22.28 dB, respectively). Furthermore, ameaningful difference was observed between Leq values of commercial, residential,commercial-residential, and green space urban applications, and the central parts ofthe city showed noticeable noise pollution. Taken together, due to being exposed tohigher than the acceptable threshold noise level, the residents of Sanandaj will beendangered to health problems in the near future; thus consideration should be givento the noise pollution sources.     

Response overshoot: a challenge for the application of polymer gel dosimeters

Journal of Radioanalytical and Nuclear Chemistry - Studies of phosphorus cycling in the ocean have been greatly facilitated by the use of high molar activity 32P- and 33P-labeled phosphate...     

Kinetics,isotherms and thermodynamic modeling of Mn2+ and Zn2+ single and binary removal using mercapto functionalized silica aerogel

Heavy metals pollution is one of today's concerns of human societies. In the present project, mercapto functionalized silica aerogel was used to remove Zn²⁺ and Mn²⁺ from aqueous solution. The simultaneous adsorption of these ions has also studied. The kinetics and thermodynamics of the adsorption process as well as various isotherm models have been investigated. The results show that the adsorption process is spontaneous and favorable. The adsorption followed the Langmuir model and the maximum adsorption capacity for manganese and zinc was 1.38 and 1.33?mmol/lit, respectively. The kinetics of the adsorption process corresponds to the pseudo-second order equation. Intra particle diffusion model illustrated a greater affinity to the zinc ion, which confirmed by simultaneous adsorption results.     

Ultrasound‐assisted green synthesis of Cu‐based complexes of β‐cyclodextrin and their SOD‐like activity

A novel Cu–Zn β‐cyclodextrin (CuZn/β‐CD) model compound was synthesized under ultrasound irradiation to mimic the functionality of copper zinc superoxide dismutase (CuZnSOD). For comparison, Cu/β‐CD and Zn/β‐CD complexes were also synthesized via a sonochemical approach. The obtained complexes were characterized by FTIR, ICP‐OES, UV–vis and Scanning electron microscopy‐Energy dispersive X‐ray (SEM‐EDX) techniques. The SOD activity of the complexes was evaluated by a pyrogallol autoxidation method. These enzyme‐mimetic materials scavenge ambient free radicals, with the potential to provide significant antioxidant protection (scavenging ability > 70%).     

Effect of inorganic oxide supports on the activity of chromium‐based catalysts in ethylene trimerization

Novel heterogeneous catalysts were prepared using immobilization of bis(2‐decylsulfanylethyl)amine–CrCl₃ (Cr‐SNS‐D) on various supports, namely commercial TiO₂, Al₂O₃ and magnetic Fe₃O₄@SiO₂ nanoparticles, to yield solid catalysts denoted as support@Cr‐SNS‐D. The structure of the catalysts was confirmed on the basis of spectroscopic analyses, N₂ adsorption–desorption and inductively coupled plasma (ICP) analysis. The surface areas of Al₂O₃@Cr‐SNS‐D, Fe₃O₄@SiO₂@Cr‐SNS‐D and TiO₂@Cr‐SNS‐D catalysts were determined to be 70, 23 and 41 m² g^?1, respectively. A decrease in surface area from that of the supports clearly establishes accurate immobilization of Cr‐SNS‐D catalyst on the surface of the parent carriers. The loading of Cr was determined to be 0.02, 0.16 and 0.11 mmol g^?1 for Cr‐SNS‐D supported on TiO₂, Al₂O₃ and Fe₃O₄@SiO₂, respectively, using ICP analysis. After preparation and full characterization of the catalysts, ethylene trimerization reaction was accomplished in 40 ml of dry toluene, at 80°C and 25 bar ethylene pressure and in the presence of methylaluminoxane (Al/Cr = 700) within 30 min. The supported chromium catalysts were found to be efficient and selective for the ethylene trimerization reaction. The highest activity (74 650 g_1‐hexene g_Cr^?1 h^?1), as well as no polyethylene formation during reaction processes, was observed when TiO₂ was used as the catalyst support.     

Magnetically recyclable nano copper/chitosan in O‐arylation of phenols with aryl halides

Interaction of chitosan (CS) with Fe₃O₄, followed by embedding Cu nanoparticles (NPs) on the magnetic surface through adsorption of Cu²⁺, and its reduction to Cu^o via NaBH₄, offers a reusable efficient catalyst (Fe₃O₄/CS‐Cu NPs) that is employed in cross‐coupling reactions of aryl halides with phenols, which affords the corresponding diaryl ethers, with good to excellent yields. The catalyst is completely recoverable from the reaction mixture by using an external magnet. It can be reused four times, without significant loss in its catalytic activity.