Polydepsipeptides, copolymers of α - amino acids and α - hydroxy acids, could prove to be a valuable new class of synthetic biodegradable polymers. In this paper, steps in synthesis of poly (dl-lactide-co-3, 6-dimethylmorpholine-2,5-dione) from dl-Iactide and dl-3,6-dimethylmorpholine-2,5-dione was explained. dl -Lactide was synthesized from lactic acid. In the reaction of 2-bromopropionyl chloride and dl-alanine, N-(2-bromopropionyl)-dl-alanine was prepared and this material was converted to its salt and finally this salt was converted to 3, 6-dimethylmorpholine-2, 5-dione in a sublimer. These two monomers, that is, dl -lactide and dl-3, 6-dimethylmorpholine-2, 5-dione was polymerized by ring-opening polymerization. FT-IR, 1H NMR, 13C NMR Spectra were used for structure elucidation of all intermediate compounds and final product.  

Carbon nano-materials were applied to the gas diffusion layers of PEMFC. Gas diffusion layers consist of gas diffusion medium (carbon cloth or carbon paper) and micro-layers. Carbon actives have been widely used for the micro-layers. Main functions of gas diffusion layers are distribution of reactants to the active site of electrode, management of water supplied and/or generated and enhancement of electrical contact between the electrode and the bipolar plates. In this work, nano-tubes are adopted to the micro-layer of gas diffusion layers. The micro-porous layer of the GDLs as seen under scanning electron microscope showed excellent surface morphology showing the reinforcement with nano-tubes and the surface homogeneity without any cracks. In this work, the 50% of carbon nano tube and 50% of carbon active contained micro-layer case showed the best I-V performance. By applying nano-materials, thinner micro-layers can be fabricated. This newly made micro-layer showed higher gas permeability and good electric conductivity with similar degree of water management as well as enhanced performance.

This work is designed to study the energy management of a Proton Exchange Membrane Fuel Cell (PEMFC), which is based on the activity and management of water and its effect on the electrolyte membrane (FC) as a function of the influx of hydrogen and oxygen, by taking into account the influence of humidification on the implementation of this electrical system to avoid drying and flooding that can cause deterioration of the FC. The cell voltage and system efficiency are also influenced by current density and operating temperature, and simulation results on MATLAB/Simulink are discussed.

Arterial drug concentration distribution determines local toxicity. The safety issues dealing with Drug-Eluting Stents reveal the needs for investigation on the effective factors contributing to fluctuations in arterial drug uptake. The current study focuses on the importance of hypertension as an important and controversial risk factor among researchers on the efficacy of Heparin-Eluting Stents. For this purpose, the effect of blood pressure is systematically investigated in certain cardiac cycle modes. A comprehensive study is conducted on two classes, pulsatile (time-dependent), to have a more realistic simulation, and non-pulsatile (time-independent) blood flow, each one in four modes. The governing equations applied to drug release dynamics are obtained based on porous media theory. The equations are solved numerically using the Finite Volume Method. Results reveal that there is a significant difference when the plasma flow considered, and when it is neglected (regardless of time dependency). Moreover, the concentration level is more decreased in pulsatile blood flow rather than the non-pulsatile blood flow, although the penetration depth for pressure and concentration are nearly 20% and 5% of the wall thickness, respectively. In other words, the mass experienced by the arterial wall is lower in pulsatile blood flow in comparison to non-pulsatile blood flow. As a consequence, the risk of toxicity is declined as the blood pressure increases. Also, it can be seen that the polymer is diffusion-dominated so that no significant changes in the release characteristics are observed in the presence of the plasma filtration.

Labelled organic compounds have been widely applied to solve the research problems in life, science and chemistry. The preparation of labelled compounds with carbon-14 and tritium-3 are probably more extensively and variously used in compare with any other isotopes. These isotopes emit only beta-particle. In this paper the synthesis of DL [3H] Leucine which was prepared for the first time in Iran is described. This compound is used for diagnosis of talasemi disease. The synthetic pathwayis achieved by using the condensation of methyl allyl chloride with diethyl acetamido malonate in the presence of sodium ethoxid in ethanol .In the next step of the synthesis. the latter compound was hydrogenated with 3H2(g.) over the Adams catalyst in chloroform. which was produced ethyl 2- acetamido-2- carbetoxy -4-methyl pentanoate with a yield of 100%. In final step, the resulted product was converted directly to [4.5-3H] Leucine with the specific activity 5 Ci/mmol. by reflaxing with the hydrobromic acid of 48%.

Aim: The aim of this study was to compare the effects of Ethylen glycol tetra acetic acid (EGTA) and EDTA for their smear layer removal capability using scanning electron microscopy technique.Material and Methods: A group of 28 single rooted teeth were instrumented to size 60 master file. Four teeth were also kept as control while the remaining teeth were divided into two groups. Group A: in which 12teeth were irrigated with 10 ml of 17% EGTA for 2 minutes? Group B: consisted of 12teeth irrigated with 10 ml of 17% EDTA for 2 minutes. Both groups were then irrigated with 10 ml of 5% Naocl. the control group were just irrigated with 10 ml of 5 % Naocl. All teeth in then the control group were only irrigated with 10 ml of 5% Nacl. Specimeus were then sectioned longitudinally. A scanning electrone microscope was wsed to in vetig ate the intenal surfaces of the canal.Results: EGTA chelated dentin surface more conservatively than EDTA without causing erosion.Conclusion: It seems that EGTA can be used safely to remove smear layer from the canal surfaces.