alireza soltani - Academia.edu (original) (raw)

Papers by alireza soltani

Sustainable Materials and Technologies, 2022

For decades, behavioral scientists have used the matching law to quantify how animals distribute ... more For decades, behavioral scientists have used the matching law to quantify how animals distribute their choices between multiple options in response to reinforcement they receive. More recently, many reinforcement learning (RL) models have been developed to explain choice by integrating reward feedback over time. Despite reasonable success of RL models in capturing choice on a trial-by-trial basis, these models cannot capture variability in matching. To address this, we developed novel metrics based on information theory and applied them to choice data from dynamic learning tasks in mice and monkeys. We found that a single entropy-based metric can explain 50% and 41% of variance in matching in mice and monkeys, respectively. We then used limitations of existing RL models in capturing entropy-based metrics to construct a more accurate model of choice. Together, our novel entropy-based metrics provide a powerful, model-free tool to predict adaptive choice behavior and reveal underlying...

Journal of Molecular Structure, 2021

Abstract Sulfasalazine (SSZ) is a sulfa drug that is used to treat various forms of arthritis and... more Abstract Sulfasalazine (SSZ) is a sulfa drug that is used to treat various forms of arthritis and is known for its ability to induce apoptosis in T lymphocytes and cancer cells. To enhance its solubility and efficacy, we encapsulated SSZ within a micellar/niosomal formulation. The micellar/niosomal formulation was prepared using an amphiphilic self-assembly method involving squalene (S) and tween 80 (T8) for the first time. The encapsulation and release of SSZ from the nanocarrier was characterized. The percent encapsulation efficiency of SSZ was 99.5 ± 0.2 %, 90.5 ± 0.5 %, and 80.5 ± 0.8 % for the 5:100, 7.5:100, and 10:100 (w/w) ratios of SSZ:total weight of ST8 micellar/niosomal vesicles (ST8MNVs), respectively. A higher loading of 20:100 (w/w) led to SSZ diffusion from the vesicular systems within 24 h. The cytotoxic activity of the SSZ-encapsulated ST8MNVs was evaluated against different cancer cell lines. Encapsulation and the use of the nanoformulations improved the effectiveness of SSZ in promoting apoptosis in MDA-MB-231, MCF-7, and HeLa cell lines, by reducing the IC50 value by at least five folds. The high loading and encapsulation of SSZ within the micellar/niosomal formulation together with its greater water solubility enhanced the bioavailability of the drug, improving its potential for biomedical and therapeutic applications.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2021

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Cognition, 2020

Most cognitive processes are studied using abstract or synthetic stimuli with specific features t... more Most cognitive processes are studied using abstract or synthetic stimuli with specific features to fully control what is presented to subjects. However, recent studies have revealed enhancements of cognitive capacities (such as working memory) when processing naturalistic versus abstract stimuli. Using abstract stimuli constructed from distinct visual features (e.g., color and shape), we have recently shown that human subjects can learn multidimensional stimulus-reward associations via initially estimating reward value of individual features (feature-based learning) before gradually switching to learning about reward value of individual stimuli (object-based learning). Here, we examined whether similar strategies are adopted during learning about naturalistic stimuli that are clearly perceived as objects (instead of a combination of features) and contain both task-relevant and irrelevant features. We found that similar to learning about abstract stimuli, subjects initially adopted feature-based learning more strongly before transitioning to object-based learning. However, there were three key differences between learning about naturalistic and abstract stimuli. First, compared with abstract stimuli, the initial learning strategy was less feature-based for naturalistic stimuli. Second, subjects transitioned to object-based learning faster for naturalistic stimuli. Third, unexpectedly, subjects were more likely to adopt feature-based learning for naturalistic stimuli, both at the steady state and overall. These results suggest that despite the stronger tendency to perceive naturalistic stimuli as objects, which leads to greater likelihood of using object-based learning as the initial strategy and a faster transition to object-based learning, the influence of individual features on learning is stronger for these stimuli such that ultimately the object-based strategy is adopted less. Overall, our findings suggest that feature-based learning is a general initial strategy for learning about reward value of all types of multi-dimensional stimuli.

Primate vision is characterized by constant, sequential processing and selection of visual target... more Primate vision is characterized by constant, sequential processing and selection of visual targets to fixate. Although expected reward is known to influence both processing and selection of visual targets, similarities and differences between these effects remains unclear mainly because they have been measured in separate tasks. Using a novel paradigm, we simultaneously measured the effects of reward outcomes and expected reward on target selection and sensitivity to visual motion in monkeys. Monkeys freely chose between two visual targets and received a juice reward with varying probability for eye movements made to either of them. Targets were stationary apertures of drifting gratings, causing the endpoints of eye movements to these targets to be systematically biased in the direction of motion. We used this motion-induced bias as a measure of sensitivity to visual motion on each trial. We then performed different analyses to explore effects of objective and subjective reward valu...

When making choices, collecting more information is beneficial but comes at the cost of sacrifici... more When making choices, collecting more information is beneficial but comes at the cost of sacrificing time that could be allocated to making other potentially rewarding decisions. To investigate how the brain balances these costs and benefits, we conducted a series of novel experiments in humans and simulated various computational models. Under six levels of time pressure, subjects made decisions either by integrating sensory information over time or by dynamically combining sensory and reward information over time. We found that during sensory integration, time pressure reduced performance as the deadline approached, and choice was more strongly influenced by the most recent sensory evidence. By fitting performance and reaction time with various models we found that our experimental results are more compatible with leaky integration of sensory information with an urgency signal or a decision process based on stochastic transitions between discrete states modulated by an urgency signa...

Measurements of response time (RT) have long been used to infer neural processes underlying vario... more Measurements of response time (RT) have long been used to infer neural processes underlying various cognitive functions such as working memory, attention, and decision making. However, it is currently unknown if RT is also informative about various stages of value-based choice, particularly how reward values are constructed. To investigate these questions, we analyzed the pattern of RT during a set of multi-dimensional learning and decision-making tasks that can prompt subjects to adopt different learning strategies. In our experiments, subjects could use reward feedback to directly learn reward values associated with possible choice options (object-based learning). Alternatively, they could learn reward values of options’ features (e.g. color, shape) and combine these values to estimate reward values for individual options (feature-based learning). We found that RT was slower when the difference between subjects’ estimates of reward probabilities for the two alternative objects on ...

Decisions we face in real life are inherently risky and can result in one of many possible outcom... more Decisions we face in real life are inherently risky and can result in one of many possible outcomes. However, most of what we know about choice under risk is based on studies that use options with only two possible outcomes (simple gambles), so it remains unclear how the brain constructs reward values for more complex risky options faced in real life. To address this question, we combined experimental and modeling approaches to examine choice between pairs of simple gambles and pairs of three-outcome gambles in male and female human subjects. We found that subjects evaluated individual outcomes of three-outcome gambles by multiplying functions of reward magnitude and probability. To construct the overall value of each gamble, however, most subjects differentially weighted possible outcomes based on either reward magnitude or probability. These results reveal a novel dissociation between how reward information is processed when evaluating complex gambles: valuation of each outcome is...

Synthetic Metals, 2017

In this work, we have investigated the adsorption of a hydrogen atom and molecules on the Pd and ... more In this work, we have investigated the adsorption of a hydrogen atom and molecules on the Pd and Co-decorated C 24 fullerenes by means of density functional theory. The hydrogen interaction mechanism with host cages by regarding the adsorption energy and charge density variations was studied. It is found that both Pd and Co atoms have a significant role to increase the adsorption energy as an exothermal process. This energy change is strongly dependent on the electrostatic potential variations around the Pd and Co atoms doped on the C 24 fullerene. Also, the HOMO-LUMO gap (E g) for C 24 fullerene varies from 1.20 to 0.76 and 0.86 eV, after decorations of Co and Pd atoms, respectively. More consideration such as thermodynamics parameter, electronic density of states, and charge density analysis are discussed in the context.

Russian Journal of Physical Chemistry A, 2017

The adsorption of hydrogen peroxide (H 2 O 2) molecule on the outer and inner surfaces of Al 12 N... more The adsorption of hydrogen peroxide (H 2 O 2) molecule on the outer and inner surfaces of Al 12 N 12 nano-cage in terms of energetic, geometric, and electronic properties has been investigated using the density functional theory (DFT) calculations by B3LYP-D and M06-2X methods and 6-31G** basis set. It has been found that H 2 O 2 molecule can be strongly chemisorbed (-3.45 eV) over the outer surface of the Al 12 N 12 nanocage, where the adsorption energy depending upon its orientation with the nano-cage. Moreover, the adsorption of two H 2 O 2 molecules on the outside surface of adsorbent is about-2.05 eV, while the adsorption of the molecule trapped inside adsorbent is about-1.81 eV. It was found that the H 2 O 2 adsorption on the outer and inner surfaces of Al 12 N 12 nano-cage leads to slightly lower energy gap and increasing the dipole moment of adsorbent.

Journal of Molecular Structure, 2017

We report on the experimental, crystal structure and computational investigation of a new class o... more We report on the experimental, crystal structure and computational investigation of a new class of xanthenes obtained by the reaction of salicylaldehyde and its derivatives with, 5,5-Dimethylcyclohexane-1,3-dione (Dimedone). The synthesized xanthenes were characterized by state-of-the-art techniques, such as IR, Raman, 1 H and 13 C NMR, Single Crystal X-ray crystallography, UV-Vis and photophysical measurements. The structure, groundandexcited-state properties of one xanthene derivative was investigated using Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT) calculations with and without solvent (ethanol). The optimized geometries and predicted IR frequencies were in good agreement with experimental data. Hirshfeld surface analyses were carried out to gain insight on the close-contact interactions of the crystal, where hydrogen showed the highest contribution (66.1%). The synthetic route proposed in this work does not use any catalysts and leads to high yields (75-85 %), therefore being an interesting alternative to synthesize xanthene derivatives.

RSC Advances, 2016

The most stable interaction of 5-FU drug molecule from its nitrogen head (di-enol form) over B12N... more The most stable interaction of 5-FU drug molecule from its nitrogen head (di-enol form) over B12N12 nano-cage is determined using density functional theory calculations.

Throughout history, most traditional cities and building practices evolved out of necessity and n... more Throughout history, most traditional cities and building practices evolved out of necessity and not a supplydriven ideology. Therefore, their sense of sustainability emerged from having found resonance with nature, human-environment interaction, its pace and cyclical progression and that's why they have withstood the test of time and appealed to a variety of functional needs. Much of their charm was a product of the way they related to the character of the neighborhood and allowed for democratic expressions. The patrimony of indigenously designed and developed urban places and spaces is a clear fact; built environments which are culturally rooted, locally produced, and technologically adapted in time and space. Their potential responsiveness to the needs of a changing social and functional world was achieved through mixed activity patterns, organic geometry and human-environment interaction. Historic cities of Iran were no exception and have evolved out of an unique sustainable ideology allowing resonance with nature, human-environment interaction as well as creating socio-cultural patterns for a satisfactory urban life. This sustainable approach has been manifested in characteristics such as direction to prevailing wind and sun, utilization of vegetation and other natural elements, vernacular materials and so on. In this paper the intention is to analyze the conceptions of sustainability in urban structure of Iranian historical cities.

Journal of Physics and Chemistry of Solids, 2014

The adsorption of OCN-(cyanato anion) on boron nitride (B 12 N 12 and B 16 N 16) and boron phosph... more The adsorption of OCN-(cyanato anion) on boron nitride (B 12 N 12 and B 16 N 16) and boron phosphide nano-cages (B 12 P 12 and B 16 P 16) in terms of energetic, geometric, and electronic properties are studied using density functional theory calculations. Our study results indicated that the first OCNstrongly prefers to be adsorbed from its N atom upon B atoms of the nanocages than the O atoms of OCN-. These findings have been rationalized using frontier molecular orbitals and total electron density plots. The energy gap of the B 12 P 12 is significantly reduced upon the adsorption of OCNcompared to B 12 N 12 , thus leading to the increase in electrical conductance of nano-cage.

Physica B: Condensed Matter, 2014

ABSTRACT Density-functional theory calculations are used to investigate the interaction of Al12N1... more ABSTRACT Density-functional theory calculations are used to investigate the interaction of Al12N12 and B12N12 clusters with the adenine (A), uracil (U), and cytosine (C) molecules. The current calculations demonstrate that these hybrid adsorbent materials are able to adsorb the adenine, uracil, and cytosine molecules through exothermic processes. Our theoretical results reveal improvement in the adsorption of adenine, uracil, and cytosine on Al12N12 and B12N12. It is observed that B12N12 is highly sensitive to adenine, uracil, and cytosine compared with Al12N12 to serve as a biochemical sensor.

Monatshefte für Chemie - Chemical Monthly, 2014

The electronic and geometrical structures of acetone adsorption on Al 12 N 12 nanocage have been ... more The electronic and geometrical structures of acetone adsorption on Al 12 N 12 nanocage have been investigated using DFT calculations, by means of B3LYP functional with 6-31G* and 6-31 ? G*basis sets. The results showed that the acetone binds to the Al atom of Al 12 N 12 with adsorption enthalpies of-119.12 kJ/mol (6-31G* basis set) and about-116.94 kJ/mol (6-31 ? G* basis set) for the first acetone and-116.57 kJ/mol (6-31G* basis set) and about-113.89 kJ/mol (6-31 ? G* basis set) for the second one (per each molecule). On the basis of calculated density of states, adsorption of acetone molecule on the Al 12 N 12 surface induces some changes in electronic properties of the nanocage. For the systems, the field emission properties are improved upon the acetone adsorption and the thermodynamic values indicated that this process is exothermic. On the basis of the results, Al 12 N 12 nanocage can be a promising candidate for adsorption of acetone from environmental systems.

The Journal of Neuroscience, 2010

The primate visual system continuously selects spatial proscribed regions, features or objects fo... more The primate visual system continuously selects spatial proscribed regions, features or objects for further processing. These selection mechanisms—collectively termed selective visual attention—are guided by intrinsic, bottom-up and by task-dependent, top-down signals. While much psychophysical research has shown that overt and covert attention is partially allocated based on saliency-driven exogenous signals, it is unclear how this is accomplished at the neuronal level. Recent electrophysiological experiments in monkeys point to the gradual emergence of saliency signals when ascending the dorsal visual stream and to the influence of top-down attention on these signals. To elucidate the neural mechanisms underlying these observations, we construct a biologically plausible network of spiking neurons to simulate the formation of saliency signals in different cortical areas. We find that saliency signals are rapidly generated through lateral excitation and inhibition in successive layer...

Superlattices and Microstructures, 2014

Superlattices and Microstructures, 2013

At present work, we explore the adsorption properties of the 5-Aminolevulinic acid (5ALA) interac... more At present work, we explore the adsorption properties of the 5-Aminolevulinic acid (5ALA) interacting with SWCNTs, C 60 , and C 24 by density functional ab initio (DFT) calculations. It was found that the electronic structure of C 60 is more sensitive to the presence of 5ALA in comparison with C 24 , (5, 5), and (9, 0) SWCNT. Our results demonstrate that the interactions between 5ALA and the nanostructures are chemisorption. The natural bond orbital (NBO) and density of states (DOSs) analyses represent that the nature of 5ALA adsorption on the applied nanostructures is permanently electrostatic rather than covalent.