mohammad heydarizadeh

In the present paper, bovine serum albumin (BSA) was studied for extraction case from a buffer solution through a new version of modified magnetic chitosan nanocomposite.  Post-modification of this magnetic chitosan led to conversion of amine groups to dithiocarbamate on the surface of chitosan which was wrapped to superparamagnetic iron oxide nanoparticles (SPION). Chitosan was converted to magnetic chitosan over co-precipitation of Fe2+ and Fe3+ under alkali conditions. Amines of chitosan were also converted to dithiocarbamate over the reaction of carbon disulfide. Study of the synthesized support in BSA extraction was achieved in further experiments.

This paper presents a methodology to assist a strategic producer in making informed decisions on generation investment in power market environment. This producer, facing a number of uncertainties which affect its expected profit, endeavors to maximize its profit and at the same time manages the risk of these uncertainties. In order to present the strategic behavior of the producer, supply function is used through a risk constrained two-stage stochastic bi-level model. The upper-level problem considers risk management of the investment decisions and strategic production actions, and the lower-level problems correspond to pool market clearing under different operating conditions. Uncertainties due to demand quantity and biding, rival investment and rival contribution in the market, are taken into consideration through scenarios. In order to model the risk management of the producer, conditional value at risk is used as a risk term. The investment is static and a single target year is considered with demand variations modeled through a number of blocks. The effectiveness of the proposed methodology is demonstrated by a case study on 24 bus IEEE test system. The results are reported and discussed.

Considering the fact that rocks fail faster under tensile stress, rock tensile strength is of great importance in applications such as blasting, rock fragmentation, slope stability, hydraulic fracturing, caprock integrity, and geothermal energy extraction. There are two direct and indirect methods to measure tensile strength. Since direct methods always encompass difficulties in test setup, indirect methods, specifically the Brazilian test, have often been employed for tensile strength measurement. Tensile failure is technically attributed to crack propagation in rock. Fracture mechanics has significant potential for the determination of crack behaviour as well as propagation pattern. To apply Brazilian tests, cracked disc geometry has been suggested by the International Society for Rock Mechanics ISRM. Accordingly, a comprehensive study is necessary to evaluate stress field and stress intensity factor (SIF) around the crack in the centre of the specimen. In this paper, superposition principle is employed to solve the problem of cracked straight-through Brazilian disc (CSTBD), using two methods of dislocation and complex stress function. Stress field and SIF in the vicinity of the crack tip are then calculated. With the proposed method, the magnitude of critical load for crack initiation in structures can be predicted. This method is valid for any crack of any arbitrary length and angle. In addition, numerical modelling has been carried out for the Brazilian disc. Finally, the analytical solution has been compared with numerical modelling results showing the same outcome for both methods.