Sharif Digital Repository

La0.3Sr0.7FeO3-δ (LSF) perovskite was prepared according to two methods: (1) applying new phenolic derivative of serine amino acid (L) as chelating agent, and (2) in absence of L as ligand-free perovskite (LFP). The newly prepared aminophenolic ligand L was fully characterized by 1H and 13C NMR, IR as well as elemental analysis while the LSF perovskite samples were characterized using the IR spectra, powder x-ray diffraction (PXRD) patterns, and SEM micrographs. The PXRD pattern obtained for the perovskite prepared by L (PPP) indicated on the presence of pure perovskite phase. The hydrogen permeation through PPP and LFP membranes with thickness of 1.0mm were measured as a function of... 

An efficient synthesis of polycyclic indole derivatives is achieved via domino Knoevenagel - hetero-Diels - Alder reaction of O-acrylated salicylaldehyde derivatives with dihydroindole-2-thiones in H2O as solvent. The products are formed in good-to-excellent yields with high regio- and stereoselectivity  

New indeno- and naphtho-fused thiophenes were synthesized from reaction of 2-bromo-1-indanone and 2-bromo-1-tetralone with arylthioacetamides in good yields  

The evolution of robotic technology has heightened the demands for robots capable of social interaction with humans, also known as social robots. The encouraging prospects of deploying this advanced assistive tool in entertainment, healthcare, and education have, in turn, promoted substantial growth in studies conducted on the human-robot interaction (HRI) topic. One hot HRI subject is the examination of social robots' efficacy within various educational scenarios, e.g., word learning. In the context of word learning, fast mapping (FM) is a well-established technique through which novel words are taught by contrasting them with previously known words. The concept of this approach originates... 

A systematic change of HZSM-5 (HZ5) as a catalyst of the methanol to aromatics (MTA) reaction was undertaken by employing a fixed-bed tubular-type reactor under ambient pressure, applying a weight hourly space velocity (WHSV) of 2 h-1 at 375 °C, as the first report on the application of low-Si/Al-ratio alkaline-[Mo,Na]-HZSM-5 in the MTA process. To characterize the surface and textural properties of the catalysts, powder X-ray diffraction (PXRD), nitrogen adsorption/desorption, temperature-programmed desorption of ammonia (NH3-TPD), pyridine-infrared spectroscopy (Py-IR), thermogravimetric analysis (TGA), and energy-dispersive X-ray (EDX) methods were employed. Gas chromatography (GC) and... 

Abstract In this work, two [60] fullerene derivatives were employed as flow improvers for waxy crude oil to reduce problems caused by the crystallization of paraffin during the production and/or transportation of the crude oil. These amine-based derivatives of [60] fullerene have been applied as wax inhibitor for improvement of rheological performance as well as pour point depressant in a waxy crude oil. Moreover, the influence of these [60] fullerene derivatives on the viscosity and pour point was also investigated in an Iranian waxy crude oil sample. The [60] fullerene derivatives were simply prepared by stirring a solution of [60] fullerene and two lipophilic amines. The results similarly... 

A new one-pot synthesis of hitherto unknown polyheterocyclic systems via tandem C-alkylation and intramolecular O-alkylation of 4-hydroxycoumarin or 4-hydroxypyran-2-one with quinolinium salts in excellent yields (71-89%) is reported. The present approach provides a powerful route into polycyclic structures containing nitrogen and oxygen related to alkaloids  

Dibenzazocines were prepared via tandem dinucleophilic addition of phenols to quinolinium salts in good yields. The procedure is efficient, simple and the substrates are easily available  

A new one-pot synthesis of thieno[2,3-b]indole ring systems is described. Condensation of cyclohexyl isocyanide with indolin-2-thiones yielded 3-cyclohexyaminomethylene-indolin-2-thiones, which upon reaction with α-halocarbonyl compounds produced the title compounds. © Georg Thieme Verlag Stuttgart  

Two new macrocyclic ligands containing 17- and 19-membered O2N3-donor aza-crowns anchored to [60]Fullerene were synthesized and characterized by employing HPLC, electrospray ionization mass (ESI-MS), 1H and 13C NMR, UV–vis, IR spectroscopies, as well as powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA) in solid state. TGA measurements revealed that upon linking each of these macrocycle rings to [60]Fullerene, the decomposition point measured for [60]Fullerene moiety was increased, indicating on the promoted stability of [60]Fullerene backbone during binding to these macrocyclic ligands. Moreover, the ground state non-covalent interactions of [60]Fullerene derivatives of... 

The synthesis of a series of benzoxazocines has been achieved in good yields by tandem C-alkylation and intramolecular O-alkylation of 1,3-dicarbonyl compounds with quinolinium salts. This is a novel example of the synthesis of eight-membered rings via a tandem process, which provides a method for the synthesis of medium-ring heterocycles  

Protecting users’ privacy over the Internet is of great importance; however, it becomes harder and harder to maintain due to the increasing complexity of network protocols and components. Therefore, investigating and understanding how data are leaked from the information transmission platforms and protocols can lead us to a more secure environment. In this paper, we propose a framework to systematically find the most vulnerable information fields in a network protocol. To this end, focusing on the transport layer security (TLS) protocol, we perform different machine-learning-based fingerprinting attacks on the collected data from more than 70 domains (websites) to understand how and where... 

An efficient, single step synthesis of hitherto unknown indole-annulated pentacyclic indolylhydroquinolines via tandem C-alkylation and intramolecular S-alkylation of indolin-2-thiones with N-alkylquinolinium salts in excellent yields (83-95%) is reported. This facile approach provides a powerful entry into polycyclic structures containing nitrogen and sulfur related to alkaloids. The structure of the product was determined by Röntgen crystal structure analysis  

A gas-phase heterogeneous kinetics is described over perovskite with formula La0.6Sr0.4Co0.8Fe0.2O3-δ (LSCF) for the oxidative coupling of methane under differential conversion conditions in a microcatalytic fixed-bed reactor. The ethane (C2H6) and carbon oxides (COX) formation and methane conversion rates were obtained as a function of methane and oxygen partial pressure under experimental conditions of: 0.20 < PC H4 < 0.82 atm, 0.04 < PO2 < 0.15 atm, and 1073 < T < 1173 K. The different kinetic models were examined and two Eley-Rideal mechanisms (a and b) were successfully performed to fit the experimental data into the theoretical relations from which two mechanisms having a first step of... 

This study scrutinizes the impacts of utilizing a socially assistive robot, the RASA robot, during speech therapy sessions for children with language disorders. Two capabilities were developed for the robotic platform to enhance children-robot interactions during speech therapy interventions: facial expression communication (containing recognition and expression) and lip-syncing. Facial expression recognition was conducted by training several well-known CNN architectures on one of the most extensive facial expressions databases, the AffectNet database, and then modifying them using the transfer learning strategy performed on the CK+ dataset. The robot’s lip-syncing capability was designed in... 

After examining the paper, the authors noticed that in Table 8, the data in two columns (the Pre-Test Scores of the Control Group and the Progress Scores of the Intervention Group) were mistakenly transposed. Please find the correct table below. © 2023, Springer Nature B.V  

An example of zeolite selectivity (MFI → MOR) driven by synthesis aging time has been studied. Using N,N,N′,N′-tetramethyl-N,N′-dipropyl-ethylenediammonium diiodide (TMDP) as an organic structure-directing agent (OSDA), the zeolite phases obtained at 2 h (MFI 97%), 8 h (MFI 84%, MOR 16%) and 24 h (MFI 43%, MOR 57%) have been characterized by powder X-ray diffraction. The results suggest that at intermediate aging time, namely 8 h and 24 h, the dominant phase (MFI) is displaced by MOR. Different techniques (FT-IR, Raman, 13C MAS NMR, TGA/DTG and HC microanalysis) have been employed to verify the OSDA integrity and occlusion inside the zeolite micropores as well as to quantify the water and... 

In this study, a three-dimensional mathematical model, based on a nonuniform droplet concentration distribution, has been developed to simulate gas absorption in a venturi scrubber. The mass transfer process was illustrated by assuming the liquid phase as a combination of droplets and film. The flow, just as the annular two-phase flow, includes a flow of liquid film layer on the walls and a flow of gas and liquid drops in the core. Peclet number was determined using experimental data reported by Viswanathan et al. (1984) for distribution of droplets across the cross section of the scrubber. The mathematical model for gas absorption was justified by comparing the theoretical predictions with... 

In this research, the samples of a low carbon steel sheet were rolled up to a thickness prestrain of 67% at three different temperatures consisted of room, blue brittleness, and subzero temperature. Microhardness, SEM, and tensile tests were carried out to evaluate the static recrystallization kinetics defined by the Avrami equation, microstructural evolution, and mechanical properties. It was found that the Avrami exponent is altered with change in prestrain temperature and it achieves the value of 1 to 1. 5. Moreover, it was indicated that prestraining at subzero temperature followed by annealing at 600 °C leads to considerable enhancement in tensile properties and kinetics of static... 

A coiled carbon nanotube (CCNT) can be formed from the distortion of parent toroidal carbon nanotube with a uniform pitch length and a uniform spring rise angle. In this research molecular dynamics simulation was carried out to assess the tensile properties of three CCNT having indexes of (3,3), (4,4), and (5,5). The results indicated that Stone-Wales defects are necessary for thermodynamic stability of the CCNTs. The stress-strain curves showed that the yield stress, yield strain, and failure strain are decreased with increase in temperature. The force-displacement curves revealed that the spring constant of these materials is highly depended on the tube diameter and rising angle, while it...