Sharif Digital Repository

Clinical and experimental observations show individual differences in the development of addiction. Increasing evidence supports the hypothesis that dopamine receptor availability in the nucleus accumbens (NAc) predisposes drug reinforcement. Here, modeling striatal-midbrain dopaminergic circuit, we propose a reinforcement learning model for addiction based on the actor-critic model of striatum. Modeling dopamine receptors in the NAc as modulators of learning rate for appetitive-but not aversive-stimuli in the critic-but not the actor-we define vulnerability to addiction as a relatively lower learning rate for the appetitive stimuli, compared to aversive stimuli, in the critic. We... 

Humanity's challenges are becoming increasingly difficult, and as these challenges become more advanced, the need for effective and intelligent action becomes more apparent. Meanwhile, the novel coronavirus disease (COVID-19) pandemic, which has plagued the world, could be considered as an opportunity to take a step toward the need for atomic engineering, compared to molecular engineering, as well as to accelerate this type of research. This approach, which can be expressed in terms of picotechnology, makes it possible to identify living cell types or in general, chemical and biological surfaces using their atomic arrays, and applied for early diagnosis even treatment of the disease. © 2020... 

We present the first density functional theory study on α-ketoglutarate dependent halogenase and focus on the mechanism starting from the iron(IV)-oxo species. The studies show that the high-valent iron(IV)-oxo species reacts with substrates via an initial and rate determining hydrogen abstraction that is characterized by a large kinetic isotope effect (KIE) of 26.7 leading to a radical intermediate. This KIE value is in good agreement with experimental data. The reaction proceeds via two-state reactivity patterns on competing quintet and septet spin state surfaces with close lying hydrogen abstraction barriers. However the septet spin radical intermediate gives very high barriers for... 

A new photocatalytic filtration membrane was prepared by grafting of Ag–Au bi-plasmonic shell-on TiO2@Fe3O4 nanoparticles as a magnetically-separable heterogeneous photocatalyst to a poly acrylic acid-modified cellulose acetate membrane for decomposition and removal of methyl orange as a model pollutant from textile wastewater samples. Eight photocatalysts including five Au NPs-modified TiO2@Fe3O4 NPs and three Ag-Au bi-plasmonic NPs-decorated TiO2@Fe3O4 NPs with different shell thickness were synthesized and characterized by TEM, UV–vis, and SEM techniques and their photocatalytic activity was assessed using two radiation sources. After selection of optimum photocatalyst and modification of...