فهرست مطالب hajieh bastami

In present computational survey, we are compared and contrasted electronic effects of C20 and its C20-2nTinBn heterofullerenic derivatives with n = 1-5, at density functional theory (DFT). All nanocages are true minima and none of them collapses to deformed open cage as segregated nanostructure. Isolating five single hetero bonds of Ti—B via either one double bond of C═C or one carbon atom is a suitable method for reaching highly substituted stable heterofullerene i.e. pen-shell C10Ti5B5 since it prevents from weak homo bonding of Ti—Ti and B—B. The C1-C18Ti1B1 heterofullerene can avoid from the most strained directly fused five-pentagon configuration, but its open-shell electronic structure with highly pyramidalized titanium atom (126.59° i.e. 3-4 times relation to C20) may render it too reactive to be observed under typical experimental conditions. The calculated binding energy (B.E.) shows C10Ti5B5 as the most stable heterofullerene. Contrary on B.E., the absolute heat of atomization of heterofullerenes decreases as number of substituting Ti―B unit (n) increases. Hence, substitution effect on binding energy is more significant than heat of atomization. Compared to the previously reported material such Ti-decorated B38 nanofullerene as a suitable hydrogen storage with B.E. of 5.67 eV/atom, our studied C20-2nTinBn heterofullerenes show the higher B.E. with range of 12.25 to 38.03 eV/atom, the higher stability and the higher capacity for hydrogen storage. Interestingly, C18Ti1B1 heterofullerene must be not only kinetically stable against electronic excitations but also based on natural bond orbital (NBO) analysis, the highest charge transfer (CT) is take placed from πC=C bonds to the neighboring LP*B, LP*Ti and σ*Ti-B anti-bonds of it. Also, the exceptionally large value of nucleus-independent chemical shifts (NICS) is found for C18Ti1B1 compared to the archetypically aromatic benzene and [2.2]paracyclophane molecules.

Thorium is a radioactive metal and is actinide family of periodic table with a half-life of 14 billion years and approximately 99% is in the form of thorium-232 isotopes. From past to present it has been used as a contrast agent (in the form of thorotrast) in imaging, ceramic manufacturing, applications in aerospace industries and it is now considered a contributing element to the fuel cycle in nuclear facilities of some countries.Thorium emits alpha, beta and gamma rays. Therefor it is necessary to know the health implications and understand the consequences of exposure to this radioactive substance. Due to differences in the routes of entry of thorium into the body example of inhalation, mouth and skin, absorption and distribution and its effects on human and animals body are different. In this paper which begins with the introduction of thorium properties, after examining the pathways of its entry into the body, examples of its consequences for human, animals and the environment are discussed.

Colloidal gold nanoparticles have been used in some medical applications in past centuries. Using different sciences in the synthesis and evaluation of gold nanoparticles has been very useful. Nowadays, drug and nucleic acid delivery to a target tissue in body is one of the promising prospects for using gold nanoparticles. Moreover, gold nanoparticles with effective absorption properties of light have been useful in the diagnosis of the disease in addition to the treatment of cancerous tissues by means of photodynamic therapy, photothermal therapy and radiofrequency therapy. Since gold nanoparticles are one of the promising candidates for targeted delivery of drug, nucleic acid and modulator of angiogenesis process, not only its synthesis and its shape and size, but also its functionality is one of the key aspects of how it is intended and processed that properties such as its biological distribution and toxisity in the body. Furthermore, the efficacy and the immunological consequences of the compounds containing gold are highly dependent on its functionalization, and this field requires more and more efficient research. Considering the research on these nanoparticles, this article summarizes the work done on these nanoparticles.

In the present work, the potential and capability of Iran's waters for acquiring and installing different types of wind turbines is discussed. For this purpose, various types of offshore wind turbines such as offshore float as the latest type of wind turbines as well as various types of base fixed offshore wind turbines were studied. In addition to reviewing the state of wind turbine technology in Iran according to oceanographic features, geographical coordinates, transportation costs and the possibility of assembly and ease of installation for the northern and southern seas of Iran, the amount of wind resources, water depth and available area were also taken into consideration. Based on the SWOT model, recommendations were made for the use of different types of turbines. In a part of the research, a comparison was made between Iran and leading countries in this field. For the Caspian Sea, the type of traction base of these turbines is not recommended due to the structural complexity, difficult installation and transportation and the need for deep water, while monopile structures and the third generation of gravity are suitable options for the shallow depths of lakes. In addition, near the southern coast of Iran, due to high tides and many changes in water depth during the day and night and the impact of the tension of the restraint lines of traction platforms, the use of this structure is not recommended. Due to the high depth of water in coastal areas and very good stability in various weather conditions, spar structures are introduced as a desirable option.

The effect of samarium oxide was examined on the sintering, microstructure, and grain growth behaviors of (Co, Nb)-doped SnO2-based ceramics prepared by co-precipitation method. The sintered samples were studied through x-ray diffraction (XRD), scanning electron microscopy (SEM), and electron dispersive spectroscopy (EDS) analyses. The microstructure observations revealed that the samples were near fully dense at a sintering temperature of 1200°C for 1h. The samarium doping prevented accelerated grain growth of the SnO2-based ceramic in the final stage of the sintering. The mean grain size of the SnO2-based ceramic without Sm2O3 doping was 2.70µm, which was reduced to 0.887µm for the sample doped with 0.05mol% Sm2O3. The grain size reduction of samples doped with Sm2O3 could be attributed to the segregation of Sm2O3 at the grain boundaries.