Sharif Digital Repository

A mixture of the platinum(0) complex [Pt(PtBu3)2] and tetrakis(acetonitrile)copper(i) hexafluorophosphate in acetone activated a water molecule and gave the hydride platinum(ii) complex [PtH(CH3CN)(PtBu3)2]PF6, 1, and the hydroxide Cu(i) species. The crystal structure of complex 1 was determined by X-ray crystallography, indicating a distorted square planar geometry around the platinum center. Although three possible mechanisms are proposed for this transformation, monitoring of the reaction using NMR spectroscopy at low temperature reveals that a cooperative pathway involving formation of a Pt0-CuI dative bond complex is the most probable pathway. The hydride platinum complex 1 is stable in... 

The aim of this study is to simulate the self-assembly of the surfactant molecules with special chemical structure and bending stiffiness into bilayer membranes using a mesoscopic Dissipative Particle Dynamics (DPD) method. The surfactants are modeled with special chemical structure and bending stiffiness. To confirm that the novel model is physical, we determine the interaction parameters based on matching the compressibility and solubility of the DPD system with real physics of the uid. To match the mutual solubility for binary uids, we use the relation between DPD parameters and x-parameters in Flory-Huggins-type models. Unsaturated bonds can change the stiffiness of a lipid membrane,... 

Magnetic micelle nanoparticles with thermoresponsive behavior were designed for thermo-triggered paclitaxel delivery. For this purpose, thermoresponsive triblock copolymer poly(N-isopropyl acrylamide)-b-polycaprolactone-b-poly(N-isopropyl acrylamide) was prepared. The magnetic micelle was formed by self-assembly of triblock copolymer on the magnetite which was coated by oleic acid. The size of the magnetic micelle was between 30–40 nm reported by transmission electron microscopy. Also, dynamic light scattering indicated the hydrodynamic diameter was thermal dependent. Moreover, the drug release profile showed thermo-triggered release of paclitaxel. Thus, the smart nanocarrier has potential... 

LM13 alloy is widely used in piston industry, due to its low coefficient of thermal expansion, excellent castability and hot tear resistance. In this research effect of casting process on wear behavior of LM13 alloy was investigated. First, samples were produced using two casting processes and heat treated. Then wear behavior of these samples under dry sliding condition was examined. Results of hardness and strength tests indicated that squeeze cast specimens exhibited higher mechanical properties. Wear experiment results showed that in both squeeze and gravity cast specimens, amount of weight loss increases with increase in sliding distance which is accompanied by reduction in wear rate and... 

Magnetic micelle nanoparticles with thermoresponsive behavior were designed for thermo-triggered paclitaxel delivery. For this purpose, thermoresponsive triblock copolymer poly(N-isopropyl acrylamide)-b-polycaprolactone-b-poly(N-isopropyl acrylamide) was prepared. The magnetic micelle was formed by self-assembly of triblock copolymer on the magnetite which was coated by oleic acid. The size of the magnetic micelle was between 30–40 nm reported by transmission electron microscopy. Also, dynamic light scattering indicated the hydrodynamic diameter was thermal dependent. Moreover, the drug release profile showed thermo-triggered release of paclitaxel. Thus, the smart nanocarrier has potential... 

Aggregation of the natively unfolded protein α-synuclein (α-syn) is key to the development of Parkinson's disease (PD). Some nanoparticles (NPs) can inhibit this process and in turn be used for treatment of PD. Using simulation strategies, we show here that α-syn self-assembly is electrostatically driven. Dimerization by head-to-head monomer contact is triggered by dipole-dipole interactions and subsequently stabilized by van der Waals interactions and hydrogen bonds. Therefore, we hypothesized that charged nano-objects could interfere with this process and thus prevent α-syn fibrillation. In our simulations, positively and negatively charged graphene sheets or superparamagnetic iron oxide... 

In this article, the synthesis, characterization, and cyclic voltammetry (CV) measurements are reported for ferrocene-terminated oligophenyleneimine (OPI_Fc) and ferrocene-terminated conjugation-broken oligophenyleneimine (CB-OPI_Fc) self-assembled monolayers (SAMs) in two different electrolytes, namely, 1-ethyl-3-methylimidazolium-bis (trifluoromethyl-sulfonyl) imide (EMITFSI) ionic liquid and tetrabutylammonium hexafluorophosphate (Bu4NPF6) in acetonitrile (0.1 M solution). The SAMs were synthesized on Au surfaces by the sequential imine condensation reactions. CV was used to investigate the kinetics of electron transfer (ET) to the ferrocene, and it was observed that the standard ET rate... 

Naphthalimide derivatives provide highly versatile self-assembled systems and aggregated forms with fascinating emission properties that make them potential candidates for many applications such as bioimaging and sensing. Although various aggregated species of naphthalimide derivatives have been well documented, little is known about the correlation between their structure and photophysical properties. Here the preparation of a series of tetrameric naphthalimide molecules in which naphthalimide units are linked by bis-N-heterocyclic carbene complexes of coinage metals is described. An in-depth structural investigation into these tetramers has been carried out in solution and the solid state... 

The type of passivating ligands and the ligand exchange method influence the quality of lead sulfide quantum dot films. This imparts on the efficiency of optoelectronic devices. To get a compact arrangement of the nanocrystals in a thin film (⁓100 nm) via self-assembling, we used organic-inorganic perovskites with mixed halides for the solid-state exchange of oleic acid ligands on PbS QDs (⁓ 4 nm). Formamidinium lead halides FAPbIxBr3-x (x= 3,2,1,0) were used. X-ray spectroscopy shows that successful replacement of oleic acid with FA happens by short immersion of the films (2 min) in the solution. Transmission electron microscopy shows that nano-scale cracks, short-range ordering, and fusion... 

To evaluate the selectivity and efficiency of solid phase microextraction (SPME) fiber coatings, synthesized by sol-gel technology, roles of precursors and coating polymers were extensively investigated. An on-line combination of capillary microextraction (CME) technique and high performance liquid chromatography (HPLC) was set up to perform the investigation. Ten different fiber coatings were synthesized in which five of them contained only the precursor and the rests were prepared using both the precursor and coating polymer. All the coatings were chemically bonded to the inner surface of copper tubes, intended to be used as the CME device and already functionalized by self-assembly... 

A new technique for preparation of an unbreakable solid-phase microextraction (SPME) fiber, using sol-gel technology is developed. Primarily, an ultrathin two-dimensional intermediate film was prepared by hydrolysis of 3-(trimethoxysilyl)-1-propanthiol self-assembled monolayer grafted onto gold, then a stationary phase by electrodeposition of 3-(trimethoxysilyl) propylmethacrylate as a precursor, tetramethyl orthosilicate and polyethylene glycol as a coating polymer was produced. The scanning electron microscopy images revealed that the new fiber exhibits a rather porous and homogenous surface. The thermal stability of the fabricated fiber was investigated by thermogravimetric analysis. The... 

A mixture of multi-walled carbon nanotube/graphite paste electrode modified with a salophen complex of cobalt was prepared and was applied for the study of the electrochemical behavior of 6-mercaptopurine (MP) using cyclic and differential pulse voltammetry (DPV). An excellent electrocatalytic activity toward the oxidation of MP was achieved, which led to a considerable lowering in the anodic overpotential and remarkable increase in the response sensitivity in comparison with unmodified electrode. Utilizing DPV method, a linear dynamic range of 1-100 μM with detection limit of 0.1 μM was obtained in phosphate buffer of pH 3.0. The electrochemical detection system was very stable, and the... 

In this research, we report a magnetic pH-sensitive polymeric micelle designed for hydrophobic drug carrier in cancer treatment. This carrier was prepared by self-assembly of biodegradable triblock copolymer PEG-PCL-PEG coated on oleate-modified magnetic nanoparticles. The amphiphilic triblock copolymer was synthesized via reaction between the aldehyde group from the hydrophilic component with the amine group of the hydrophobic component. The resulting Schiff base linkage was sensitive to pH. The structure of nanocarrier was characterized by Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy (1H-NMR). Morphology and size of the magnetic... 

Surface-Enhanced Raman Spectroscopy (SERS) is a sensitive vibration spectroscopy method applied to analyze a variety of analytes, including toxins and pesticides. The SERS method is an accurate method for detecting significantly low concentrations of biomaterials and chemicals. In the present study, in order to detect atrazine pesticide, the glass fiber substrates coated with silver nanoparticles have been used as SERS plasmonic nanosensors. First, silver nanoparticles were prepared by applying a chemical approach named the Tollens' method, and the SERS plasmonic substrates (SPS) were fabricated by depositing the colloidal silver solution on a glass fiber substrate. The SERS plasmonic...