Improve the heat exchanger efficiency via examine the Graphene Oxide nanoparticles: a comprehensive study of the preparation and stability,predict the thermal conductivity and rheological properties,convection heat transfer and pressure drop

Journal of Thermal Analysis and Calorimetry - In this research, the effect of using GO/ water nanofluid as a coolant fluid in an isothermal heat transfer system was studied. At first, to evaluate...     

Synthesis of new quinoxalinophenazinediones and tetrahydrobenzodipyrrolotetrones of biological interest

The reaction of two equivalents of sodium azide with diarylaminodibromo-p-benzoquinone (I) in DMF for 15–24 h produced quinoxalinophenazinediones together with a byproduct identified as diarylaminodiaminobenzoquinone. On the other hand, the reaction of bromanil with active methylenes, such as diethyl malonate and ethyl acetoacetate, resulted in disubstitution products which, on treatment with primary amines, cyclized into benzodipyrroletetrones. Comparative antifungal and antibacterial studies were made.     

Study of effective parameters on wear behavior of rubbers based on statistical methods

This study investigates the wear, surface roughness, and temperature buildup (TBU) of styrene butadiene rubber (SBR), natural rubber (NR), and nitrile butadiene rubber (NBR) while sliding over abrasives of different sizes with the variation of normal load. Rubber properties such as tensile strength (s) and elongation at break (e) were considered as input parameters. Individual, as well as interacting effects of different parameters, were analyzed in‐depth by using statistical methods. Overall wear of rubber depends not only on the tribological system but also on mechanical properties that contribute different wear mechanisms in addition to abrasion. The abrasive particle size and 1/(se) are the first and second most significant contributing factors, respectively, to all output parameters except the wear rate where the second contributing factor is the applied load and abrasive size is the highest contributor. Larger abrasive particles deepen ploughing marks, which is enhanced by the higher load, and lead to higher surface roughness. The effect of load on TBU is negligible because of the soft nature of the rubber material.     

Synthesis of different types of carbon nanohybrid and their effects in polymer composites

Research on Chemical Intermediates - Different types of carbon nanohybrid, including carbon nanotubes–graphene (CNT–G), carbon nanospheres–graphene (CNS–G), and carbon...     

Development of novel magnetic solid-phase extraction sorbent based on Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/carbon nanosphere/polypyrrole composite and their application to the enrichment of polycyclic aromatic hydrocarbons from water samples prior to GC–FID analysis

We describe a magnetic nanocomposite that consists of Fe₃O₄/carbon nanosphere/polypyrrole (Fe₃O₄/CNS/PPy). The synthesized nanocomposites were characterized by scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. The nanocomposite was successfully applied to extract of the polycyclic aromatic hydrocarbons (PAHs) from water samples. Compared to Fe₃O₄/PPy, the Fe₃O₄/CNS/PPy nanocomposite exhibits improved properties in terms of extraction. The amount of adsorbent, salt effect, extraction time, desorption time, type, and the volume of desorption solvent were optimized. Following the desorption of the extracted analytes, the PAHs (i.e., naphthalene, 2-methylnaphthalene, 2-bromonaphthalene, fluorene, and anthracene) were quantified by gas chromatography–flame ionization detector. The PAHs can be determined in 0.05–100.00 ng mL^?1 concentration range, with limits of detection (at an S/N ratio of 3) ranging from 0.01 to 0.05 ng mL^?1. The repeatability of the method was investigated with relative standard deviations of lower than 9.9% (n = 5). Also, the recoveries from spiked real water samples were in the range of 88.9–99.0%. The results indicate that the novel material can be successfully applied for the extraction and analysis of PAHs from water samples.     

Microextraction in packed syringe by using a three-dimensional carbon nanotube/carbon nanofiber–graphene nanostructure coupled to dispersive liquid-liquid microextraction for the determination of phthalate esters in water samples

Microchimica Acta - Microextraction in packed syringe (MEPS) was combined with dispersive liquid-liquid microextraction (DLLME) for the extraction of phthalate esters (PEs) from water samples prior...     

Synthesis and some reactions of 7-methyl-5-phenyl-5H-pyrazolo[3,4-e]1,2,4-triazine-3-thiol

The title compound II has been prepared by the reaction of 3-methyl-1-phenyl-4-oxo-5-pyrazolone with thiosemicarbazide in aqueous potassium carbonate. Alkylation of II on the sulfur atom in aqueous sodium hydroxide afforded the 3-alkylthio derivatives III. Interaction of II or III with different amines yielded the 3-amino derivatives IV. The 3-hydrazino derivative IVa condensed with aromatic aldehydes in ethanol or acetic acid giving the corresponding hydrazones V.