Sharif Digital Repository

Silver nanopowder is of great importance for various medical and industrial applications. Due to the significance of the solubility of silver nanoparticles in these applications as well as the high impact of the nanophysical morphology of the powder on their solubility, we prepared nanoparticles with plate morphology by the chemical reduction of silver nitrate in a soluble phase. Then we measure its solubility in a phosphate buffer salt, which greatly resembles the human blood chemically. The size and shape of the resulting nanosilver powder and also the use of non-toxic materials in their synthesis are important factors in the production of nanosilver powder.We confirmed the successful... 

In this work, polyvinylidene difluoride (PVDF) as a ferroelectric polymer, polyaniline (PANI) and polypyrrole (PPy) as conductive polymer additives are used to fabricate high performance mesoporous CH3NH3PbI3-xClx mixed-halide perovskite solar cells in a sequential deposition method. Using polymer additives in perovskite precursor solution leads to modification of perovskite layer morphology by changing nucleation and growth of perovskite grains. Besides, conductive polymer additives in perovskite layer help to more charge carrier transfer. Power conversion efficiency has been enhanced from 10.40 % to 16.51% and to 13.21 % in ambient atmosphere in the presence of 1.0 wt. % of PVDF and PPy... 

Perovskite solar cells, with high efficiency operation, have been candidated as a cost-effective and environmentally friendly technology. Despite the great progress, there are some primarily issues remained regarding to the perovskite film and its fabrication methods. A very common perovskite cell structure is FTO/TiO2/CH3NH3PbI3/Spiro-OMeTAD/Au. Although, this structure has some advantages, lack of full surface coverage of perovskite film leads researchers to put much effort on finding other constructions. This surface inhomogeneity reduces the amount of light absorption and therefore efficiency. One way to produce a complete and uniform film is applying mixed-halide composition; such as... 

Bulk metallic glasses (BMGs), in contrast to conventional crystalline materials, are defined as metals with an amorphous and disordered atomic-scale structure. Due to the absence of dislocations and grain boundaries, BMGs have considerably unique mechanical properties such as high strength and elastic strain, high wear resistance and desirable corrosion resistance. However, they generally suffer from poor plasticity caused by an inhomogeneous deformation which leads to catastrophic failure by localization of strain into narrow regions, known as shear bands. This factor has extremely restricted their application as advanced structural materials. Furthermore, the recently discovered phenomenon... 

Morphological analysis of words plays a fundamental role in natural language processing applications such as spell checker, POS-tagging and machine translation. Among different dialects belonging to Kurdish, Northern Kurdish (Kurmanji), Central Kurdish (Sorani) and Southern Kurdish are the closest ones to each other. The central dialect of Kurdish is the second official language in Iraq and a large volume of text content is producing daily in this dialect. In this research, designing and implementation of a two-level morphological analyzer for the central Kurdish dialect is introduced. This analyzer is designed using an open source toolkit named HFST, which is a finite state transducer... 

Tin sulfide with an energy gap of about 1.1 ev is a semiconductor suitable for applications such as solar cells, lithium-ion batteries, photocatalysts and other semiconductor-based devices. There are several methods for synthesizing this semiconductor at the nanometer scale, among which the solvothermal method is an efficient, controllable and inexpensive method. By precisely controlling the parameters of this process, two-dimensional tin sulfide nanosheets with high purity and desirable morphology can be produced. In this research, tin sulfide has been synthesized by solvothermal / hydrothermal chemical method and its metallurgical properties have been studied. Effect of solvothermal... 

Polyvinylidene fluoride is highly regarded by researchers due to its piezoelectric properties, mechanical properties, chemical and thermal stability and biocompatibility. This thermoplastic polymer has a semi-crystalline structure and, depending on the crystallization conditions, has five distinct crystalline phases α, β, γ, δ and ε. The β, γ and δ phases are electroactive, and among them, the β phase has high piezoelectric activity due to its high dipole moment. This study focuses on increasing the amount of β phase in polyvinylidene fluoride and increasing its piezoelectric property. Polyvinylidene fluoride is highly miscible with oxygen containing polymers such as polymethyl... 

Nowadays environment is under demolition from various aspects which the chemical pollution can be mentioned as an example. The aim of this research is to eliminate the 4nitrophenol as a pollutant through catalysis process. In the current study, to synthesis of the gold nanoparticles on the modified molybdenum de sulfide with nickel (MNi/MoS2 (M=Au, Pt)) an effective method was utilized. In the following, the structural and morphological features of the synthesized nano composites (MNi/MoS2) via different microscopic and macroscopic methods be identified. Obtained results from identification of the materials demonstrated the expected catalysts were synthesized successfully. Finally, to... 

Polypropylene is a semi-crystalline thermoplastic used in various industries and the second most used polymer globally. Polypropylene is sensitive to degradation by o agents due to having tertiary carbon in its chain. Chlorine-based disinfectants, used to disinfect drinking water, cause the degradation of hot water pipes made of polypropylene random copolymer. The stability of polypropylene against oxidizing chemical agents depends on the type of crystalline phase and polymer morphology. This research investigated the effect of alpha, beta, and gamma crystalline phases and spherulite size on random polypropylene copolymer's chemical stability in chlorine dioxide. Three samples were prepared,...