In this study, alkaline colloidal silica was prepared by titration of an alkaline solution such as sodium silicate with silicic acid in constant range of pH  .This constant range of pH was achieved by using concentrated soduim silicate solutions as pH adjusting solutions during titration.The sodium silicate solutions  having a variety of...

Formation of effective teams of experts has played a crucial role in successful projects especially in social networks. In this paper, a new particle swarm optimization (PSO) algorithm is proposed for solving a team formation optimization problem by minimizing the communication cost among experts. The proposed algorithm is called by improved particle optimization with new swap operator (IPSONSO...

The synthesis of iron oxide nano-particles by direct thermal decomposition was studied. Simultaneous thermal analysis and Fourier transform infrared spectroscopy results confirmed the formation of iron-urea complex, and disclosed iron oxide formation mechanism. Calcination of the iron-urea complex at 200°C and 250°C for 2 hrs. resulted in the formation of maghemite along with hematite as a seco...

Proposed mechanisms for the formation of km-sized solid planetesimals face long-standing difficulties. Robust sticking mechanisms that would produce planetesimals by coagulation alone remain elusive. The gravitational collapse of smaller solids into planetesimals is opposed by stirring from turbulent gas. This proceeding describes recent works showing that “particle feedback,” the back-reaction...

The roles of sulfuric acid in new particle formation and growth in the mega-city of Beijing D. L. Yue, M. Hu, R. Y. Zhang, Z. B. Wang, J. Zheng, Z. J. Wu, A. Wiedensohler, L. Y. He, X. F. Huang, and T. Zhu State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, 100871 Beijing, China Department of Atmosph...

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The contribution of boundary layer (BL) nucleation events to total particle concentrations on the global scale has been studied by including a new particle formation mechanism in a global aerosol microphysics model. The mechanism is based on an analysis of extensive observations of particle formation in the BL at a continental surface site. It assumes that molecular clusters form at a rate prop...