Investigation of production of medical ~(82)Sr and ~(68)Ge for ~(82)Sr/~(82)Rb and ~(68)Ge/~(68)Ga generators via proton accelerator

How to operate~(82)Sr/~(82)Rb and ~(68)Ge/~(68)Ga generators used in the positron emission tomography scan process is explained, and the importance of ~(82)Sr and ~(68)Ge radionuclides for these generators is revealed. To produce medical ~(82)Sr and ~(68)Ge by means of a proton accelerator in an irradiation time of 24 h, a proton beam current of250 l A, and an energy range E_(proton)= 100 →5 MeV, the cross sections and the neutron emission spectrum curves of(p,xn) reaction processes on Rb-85, Ga-69 and Ga-71 targets were calculated, and the activities and yields of the product were simulated for the reaction processes. Additionally, the integral yields of the reaction processes were determined via the calculated cross-sectional curves and the mass stopping power obtained from the X-PMSP program. Furthermore, based on the obtained results, the appropriate reaction processes for the production of ~(82)Sr and ~(68)Ge isotopes on Rb-85, Ga-69, and Ga-71 targets are discussed.     

The effect of hydrogen shielding gas on microstructure and abrasive wear behavior in the surface modification process using the tungsten inert gas method

In this study, SAE 1020 steel surfaces were separately alloyed with preplaced high-carbon ferro-chromium (FeCr), ferro-molybdenum (FeMo), and ferro-titanium (FeTi) powders by using a tungsten inert gas (TIG) heat source. By using two different types of shielding gas compositions during the alloying process, the study investigated the effects of modified shielding gas composition on the microstructure, hardness, and abrasive wear resistance of specimens. It was observed that with modifications in shielding gas composition, the microstructure and volume hardness of the specimens changed and no cracks and voids were formed in the interface area. The X-ray examinations of the specimens identified Fe, FeTi, and FeMo phases in their microstructure as the first phase, and Cr₇C₃, Fe₃C, Fe₇C₃, and TiC phases as the second phase. As a result, it was concluded that changes in shielding gas composition in surface alloying process significantly affect specimens’ microstructure and mechanical properties.     

Galvanic corrosion of titanium-based dental implant materials

This paper describes an investigation of the corrosion behavior of Ti-based dental materials with Au, CrNi and CoCr in Ringer solution by the use of Tafel plots, Evans diagrams and EIS Nyguist diagrams. The galvanic potentials and currents obtained for various implant couples are as follows: For, Ti6Al4V/CrNi couple −0.030 V (Ag/AgCl (3 M NaCl)) and 7.94 μA cm⁻²; for Ti6Al4V/CoCr couple −0.020 V (Ag/AgCl (3 M NaCl)) and 7.08 μA cm⁻²; for Ti6Al4V/Au couple −0.020 V (Ag/AgCl (3 M NaCl)) and 5.62 μA cm⁻². The Ti6Al4V/Au couple was found to be the most suitable one against galvanic corrosion according to both the Tafel method and mixed potential theory. The corrosion behaviors of Ti6Al4V/CoCr and Ti6Al4V/CrNi couples were found to be similar.     

聚乳酸（Ingeo）染色织物碱性还原清洗工艺研究

研究了不同碱性还原清洗工艺对聚乳酸分散染料染色织物的作用效果。结果表明,聚乳酸色织物在碳酸钠2g／L,连二亚硫酸钠2g／L,温度60℃,时间15min的还原清洗工艺条件下效果最佳,不仅织物的色深值没有明显的降低,而且水洗牢度也达到了最佳值。     

The Mathematical Theory of Dynamic Load Balancing in Cellular Networks

While many interesting dynamic load balancing schemes have been proposed for efficient use of limited bandwidth and to increase the capacity of congested or hot spots (or cells) in wireless networks, to date, a comprehensive mathematical framework which encompasses all of these schemes does not exist. In this paper, we provide a unified mathematical framework for dynamic load balancing, which leads to closed-form performance expressions for evaluating the performance of some of the most important dynamic load balancing strategies proposed in the literature. To the best of our knowledge, this is the first generic theoretical framework that can be used to evaluate the performance of many different dynamic load balancing schemes with simple closed-form results. The accuracy of the results predicted by these analytical expressions derived from the theoretical framework is checked by comparing these results with simulation results provided in the literature for well-known schemes.     

On the order of the preference intensities in fuzzy AHP

We show that a recently discovered fundamental problem with the Analytic Hierarchy Process (AHP) concerning the meaning of the resultant preference intensities is also evident for the fuzzy AHP. We prove that if there is a judgmental inconsistency in the fuzzy pair-wise comparisons, it is impossible to ensure the preservation of the order regarding to preference intensities in the resultant priority vector. Further, it is shown with an example from the published literature that the order of the preference intensities may not be preserved even there is no inconsistency in the judgment set, albeit it is possible to comply with this order via using fuzzy preference programming (FPP) methodology. Finally, it is proved that if the interval judgments regarding to the decompositions of original judgments to - level sets are consistent, FPP guarantees the preservation of the order of the preference intensities at those levels.     

A Process Model of Rho GTP-binding Proteins in the Context of Phagocytosis

At the early stages of the phagocytic signalling, Rho GTP-binding proteins play a key role. With the stimulus from the cell membrane and with the help from the regulators (GEF, GAP, Effector, GDI), these proteins serve as switches that interact with their environment in a complex manner. We present a generic process model for the Rho GTP-binding proteins, and compare it with a previous model that uses ordinary differential equations. We then extend the basic model to include the behaviour of the GDIs. We discuss the challenges this extension brings and directions of further research.     

Reliability and congestion control in cognitive radio sensor networks

Communication requirements for cognitive radio sensor networks (CRSN) necessitate addressing the problems posed by dynamic spectrum access (DSA) in an inherently resource-constrained sensor networks regime. In this paper, arising challenges for reliability and congestion control due to incorporation of cognitive radio capability into sensor networks are investigated along with the open research issues. Impact of DSA, i.e., activity of licensed users, intermittent spectrum sensing and spectrum handoff functionalities based on spectrum availability, on the performance of the existing transport protocols are inspected. The objective of this paper is to point out the urgent need for a novel reliability and congestion control mechanism for CRSN. To this end, CRSN challenges for transport layer are revealed and simulation experiments are performed to demonstrate the performance of the existing transport protocols in CRSN.