Three main methods area usually used for the synthesis of star-shaped polymers, where each one has its own advantages and disadvantages. Among these techniques, "in-out" method is the best one to produce hetero-arm star polymers with narrow molecular weight distribution and long arms with active sites at the end of the second-generation arms. This method, however, has some difficulties during the synthesis of hetero-arm star polymers with styrene or dienes as the second monomers. The reason is that in the "out" step, the carbanions of the growing chains attack the existing double bonds of the other cores and produce an irreversible gel. The new "in-in" method mentioned in this paper, is used to synthesize double-star polystyrene polymers with relatively narrow molecular weight distribution and without occurrence of any gelation during the process; With the monomers, which are able to attack the existing double bonds of the cores of the star polymers, it is also possible to produce hetero-arm star polymers using this new method.

Introduction: Medical engineering systems nowadays play a very significant role in the diagnosis of various diseases. One of the most applicable devices of the medical engineering are receiving and recording devices of the heart signals, such as electrocardiograph.Application of Holter monitoring devices could be known as one of the substantial methods of electrocardiograph during daily activities. In this article, design and manufacture of Holter monitoring device based-on arm micro-controller are proposed.Materials and Methods: Atmel’s SAM3S Chip from the family of arm has an eleven-channel transformer of analogue to digital which can transform analogue signals to digital values with 12 Bit accuracy by utilizing from arm architecture used in the core of Cortex-M3 with the structure of Thumb2 processes the information with the speed of 60 MHZ. Furthermore, for receiving and reinforcement of heart signals, INA331 Chip, the product of TI Company was used. Using Chip CYRF6936, signals were transferred to the physician computer with maximum speed of one megabit/sec.Results: AT91Sam3S with the existence of the Internal Interface Circuit for communication with the external devices has enabled the system to be connected to memory cards and computer without requirement to any other interfaces. This instrumental amplifier with a single-polar feedback has 94dB Common-mode rejection ratio and 54dBamplification ratio. This chip has decreased the consumed power of the vehicle to 330 mW, which by using Lithium- polymer battery of 3000 mAH, the vehicle can be fed for one day without need for charge.Conclusion: Using wireless communication, keeping the quality of the received signal from body, limitation of information reservation was removed. Furthermore, by simplifying analogue circuits, consumed power of the device was reduced and thus time used from the device was increased without the need for recharge. In addition, by using from lowconsumption 32-Bit arm processor, high processing power and digital process capability on the heart signals will be possible easily.

The size of database and minimum number of visible stars in the field of view of star sensor are two important, influential and contradictory parameters that should be considered in design of star sensor. In this regard, the purpose of this paper is to unify the database using the uniform distribution of points on the celestial sphere with the triangulation method. For this purpose, the choice of the suitable star catalog, minimum suitable magnitude and elimination of double stars are the other steps of the uniformity process that is carried out in this study. Thus, the results of the investigations showed that Delaunay's triangulation method is faster and more accurate than the geodesic grid. Also, by simulating and performing Monte Carlo tests to count the number of stars observed in the different FOVs of a typical sensor, it was found that Delaunay's triangulation leads to a significant reduction of the probability of viewing the high density of the catalog stars in the field of view, so that the probability of observation more than 25 stars in all possible FOVs has reached to zero. On the other hand, for observing 4 or more than 4 stars at a confidence level more than 95% in non-uniform catalog, the field of view needs to be at least 12. 5 degrees, while in uniform database; this field is slightly increased to more than 13 degrees. In other words, uniformity has increased the minimum field of view needed to see the minimum number of required stars.