Sharif Digital Repository

As diseases of eye’s posterior segment has got widespread outbreak in the world, the selection of treatment is very important. Until now, intravitreal injecton has been the most common way of drug delivery to the posterior segment. Although this method is effective, halflife of some drugs in the vitreous cavity, especially those with low molecular weight, is just about some hours. Therefore, it is necessary to repeat injection in order to maintain drug concentration level of the posterior segment in the desired level. Intravitreal injection is invasive and may cause severe adverse effects such as vitreous hemorrhage, retinal detachment, endophthalmitis and cataract. In order to decrease the... 

In recent years, autonomous underwater vehicles have had an increasing role in underwater investigations. These vehicles are used in various fields, including military applications, commercial uses or scientific investigates and also mapping purposes. The test and the fabrication of these kind of vehicles are very costly and time-consuming because of not only the risk of losing the vehicle due to the various computerized errors, but also as a result of the costs of supporting staff, equipment and the structure of a process. As a result of the environment where these vehicles do their missions, there is a crucial need of control methods which have enough accuracy as well as robustness against... 

The incidence of skeletal diseases such as osteoarthritis and its progression and the need to use knee replacement implants have significant effects on the quality of life. With the improvement of living conditions and the prolongation of the average life expectancy of the society and the aging of a large part of the society, the concern about the increase in the incidence of skeletal diseases and the need to use alternative implants increases. On the other hand, many conditions such as osteoporosis and accidents lead to fractures and cavities in the bones. Bone cements are one of the most widely used materials in orthopedic and spinal surgeries.The aim of this study was to construct a... 

The in vivo cell culture process as the main part of tissue engineering was investigated through mathematical modelling and computational fluid dynamic (CFD) simulation of cartilage cell growth. Simulations can provideprocess insights for defining the optimum conditions in order to reach higher culture efficiency. In the mathematical modelling of the cell growth, it was intended to consider the most influencing factors such as biomass concentration, volume fraction, glucose concentration and shear stress levels. These results can be obtained mathematically by solving a set of partial differential equations coupling the glucose concentration, the velocity field and cell growth with each other.... 

In this piece of work, a gravity model is suggested as Iranian non-fuel export model to OIC countries. The most important results out of this model are the acquired coefficients of two variables, namely “ECO membership” and “Economic and Trade Freedom of Importer”. At first, we expected that for importer, being a member of ECO would increase the amount of trade with iran. Surprisingly, this is not what we see in a model. In fact, as ECO has not achieved any tangible success in increasing trade between its members, eastern Asian Muslim countries has become an important trade partner for iranians. This result is compatible with other pieces of researches about ECO. “Economic and Trade Freedom... 

Today’s growing interest to the underwater explorations and navigations demands to design appropriate underwater communication methods and systems. However, radio frequencies which are widely being used in free space communications, can’t be a good candidate for underwater wireless communications, due to their sever attenuation in water. On the other hand, underwater acoustic communication has been widely studied and implemented in the past decades, inspired by suitable propagation of acoustic waves through the underwater medium. Nevertheless, acoustic communication systems have limited bandwidth, lower propagation speed and lower security than optical counterparts, which suggests underwater... 

Visible light communication (VLC) uses huge license-free spectral bandwidth of visible light for high-speed wireless communication. Since each VLC access point covers a small area, handovers of mobile users are inevitable. In order to deal with these handovers, developing fast and effective resource allocation algorithms is a challenge. this paper introduces the problem of mobility-aware optimization of resources in hybrid VLC and 5G radio access technologies networks using the T-step look-ahead policy and employing the notion of handover efficiency. It is shown that the handover efficiency can correlate the overall performance of the network with future actions based on the mobility of... 

In present research, a cohesive based finite element model has been introduced to estimate median crack depth during mechanical machining on optical glasses. Development of the machining numerical model has been initiated by investigating the indentation process. Experimental results of this step have been calibrated primary numerical model which has been used in the scratch process. Due to differences between the scratch mechanism and indentation one, mathematical bases fracture formulas and cohesive relations have been developed. After extracting primary result, using them in the scratch model and developing the primary model, ultimately numerical model has been evolved to an abstract... 

Diabetes has become the most prevalent disease all among the world. One of the complications of this disease is diabetic nephropathy. Diabetic nephropathy occurs when the kidney cells encounter high glucose concentration for long periods. Kidney cells use glucose as their energy supply. However, the excess glucose in the diabetics triggers specific gene pathways, gradually leading to diabetic nephropathy. As a result, proteins’ levels and the activity of transcription factors change during the disease progression. Diabetic nephropathy is characterized by excessive deposition of the proteins comprising the extracellular matrix in the mesangium, basement membrane of the glomerulus, and in the... 

Hydrothermal supercritical method is one of the most suitable methods for metal oxide nano powder, ceramics and mineral catalyst synthesis. Metal oxides nanopowder in its pure or mixed form has wide potential application as chemical industrial catalyst, hot Superconductors, magnetic material, gas sensors and car catalyst convertors. One of the most important metal oxides aspects of application is uranium oxide as nuclear reactor fuel is used. In addition, UO2 is selective catalyst for converting methane to methanol process and Decomposition of organic Chlorine material. In Supercritical hydrothermal method done in high pressure reactor with critical to fluid, is new method for the... 

Lithium has 9 isotopes which two isotopes are stable and remaining isotopes are unstable and have half-life. Lithium stable isotopes include 6Li and 7Li that their abundance is 7.53% and 92.47% respectively. Importance of lighter lithium isotope appears for its small cross section against thermal neutron and producing fusion reactors fuel in nuclear industries. Thermal neutron absorption cross section for 6Li and 7Li are 950 barn and 37 mbarn respectively. Interesting of these isotopes in nuclear industry is due to the large difference in the absorption cross section.6Li compounds implied for tritium producing in coat of nuclear fusion reactor with DT fuel. Following tritium is used in... 

In Hemodialysis, membrane dialyser and commonly hollow fibers are used to treat patients who suffer from end stage renal failure. When blood flows into membrane, it loses uremic toxins such as urea and creatinine. On the other hand, some of the vital proteins of blood pass through the membrane or they are adsorbed on the membrane surface. The more hydrophilicity of the membrane, the less adsorption of proteins is. In this study, to achieve high hydrophilicity and low adsorption of proteins on the polysulfone membrane surface, the presence of hydrophilic nano-particles SBA-15 in membrane composition is investigated. The nano-particles with mass percentages 0.25%, 0.5 % and 1 % to one mass of... 

Present study demonstrated carbon nanoparticles/acrylate-terminated polyurethane composites as promising materials for bone implants applications. Neat polymer and composites containing nanoparticles at different loadings up to 2 wt % were prepared by in situ polymerization method. Morphological analysis exhibited that nanoparticles caused considerable phase separation between soft and hard domains as well as increased crystallinity. Mechanical analysis showed a significant improvement in mechanical properties. Maximum improvement in tensile properties of APUA was observed at 1 wt% loading of ND-HEAMs, namely 175% improvement in modulus. In vitro biocompatibility evaluation via culturing... 

Foil gas bearings are compliant surface, self-acting hydrodynamic bearings that use ambient gas as their working fluid. They do not require external pressurization and are typically constructed from several layers of sheet metal foils. In high-speed, high-temperature applications the GFB’s have the advantage of developing higher load capacities than with fixed geometry gas bearings. Since GFB’s have a complex structure consisting of a spring-like substructure with an overlying flexible surface, there exists a great variety of permutations on any given design. At current work presents a 1D model for GFB with couple solving Reynolds and Euler-Bernoulli beam equation. This mean top foil assume to... 

In the present investigation, experimental design, synthesis and evaluation of Verapamil, Albumin, Immonuglubline G and Trypsin imprinted polymers and finally Albumin imprinted poly(dopamine) nano-layer were presented. A bimodal polymerization approach as a combination of precipitation and dispersion polymerization was taken towards producing 500 nm particles for verapamil imprinting purpose. In this case the imprinting factor was 2.17. In a challenge for producing spherical particles with predefined size and pore properties the hierarchical polymerization in packed beds, using porous silica particles (particle size ca. 40 µm) was developed, as well. The method resolving the problems... 

Following heart coronary artery occlusion, heart stroke (HS) happens which leads to the creation of a dead zone on heart tissue named Myocardial Infarction (MI), the presence of which on a patient’s heart will result in succeeding HSs and the death of the patient. In this study, porous microcarriers capable of being utilized in cardiovascular tissue engineering is fabricated using a mixture of myocardium ectracellular matrix (ECM) and Chitosan (Cs). Results of Elasticity tests, SEM images, swelling behavior, biodegradability test, and cell proliferation assay showed that the scaffold consisting of 3.5% (w/w) Chitosan and 0.66% (w/w) ECM has the best potential in providing cardiovascular... 

Lameness in dairy cattle is a crucial welfare issue in dairy industry, and over the years scientists are attempting to present a detection method. In recent years it is attracting more attention to make the identification and discrimination of sounds and lames systematic and automatic. Right now, the most hopeful results have been obtained through the measurement of Ground Reaction Forces (GRF) of hooves, and analysis of load distribution between four legs, which seems applicable for wide use in dairy industry. However, the accuracy, validity, and reliability of discrimination is still far from an acceptable point, that is because of a great lack in understanding quantitative effects of the... 

Natural boron consists of two stable isotopes, mass 10 (19.3%) and mass 11 (80.7%). 10B isotope has a large thermal neutron capture cross-section and it therefore, used widely in such aspects as modern industry, military equipment, medical science and so on. specially the demand of atomic energy industry for the boron isotope is increased severely. So the separation of 10B from natural boron has received very wide attention at present. There are many kinds of methods on the boron isotopes separation, such as chemical exchange reaction and distillation in boron trifluoride method, ion exchange in boric acid solution method, counter current recycle membrane cascades in boron trifluoride... 

In this study the feasibility of xenon separation from xenon-krypton mixture was investigated by utilizing of the chromatographic column filled with nano and micron sized NaY zeolite. For this purpose the nano NaY with the yield of 100% related to Al2O3 and the average size of 98.6 nm was synthesized through the clear solution method with the mid-adding of NaOH. Furthermore, a novel method for granulation of nano zeolite was developed by utilizing sodium alginate as an external template. In this method the production of uniform spherical granules with the different sizes in the range of several milimiteres to 100 µm was easily performed. Moreover, the results showed that the adding of... 

Natural boron includes two stable isotopes 10B and 11B with 19.3 and 80.7 weight percent respectivley.10B isotope has a high thermal neutron absorption cross section. So isotope 10B material is suitable for making atomic reactor control rods. Other and even more important applications of 10B are in disclosing neutrons in order to measure neutron reactors fluxes and also are in nuclear physics laboratories and medical radiation. This isotope also is used in the pharmaceutical and the military industries. There are several methods for separating boron isotopes. Among the distillation methods, thermal diffusion of BF3, distillation of BF3, distillation of methyl borate, boric acid distillation...