Sharif Digital Repository

The respiratory system is a vital organ system which makes breathing and gas exchange possible for human's body. The loss of functionality in this system is due to either genetical problems or environmental issues like pollution or toxic gases which in many cases is inevitable. These circumstances may cause different respiratory diseases which may not be curable presently but their side effects can be partly controlled by careful and timely analysis improving the quality of patient's life. So, an appropriate device for conducting different analysis can be effective for people who suffer from respiratory diseases such as chronic obstructive pulmonary disease (COPD), asthma, occupational lung... 

As microfluidic chips are evolving to become a significant analysis tool toward POCT devices, it is crucial to make the cost and the time required for the fabrication process of these chips as low as possible. Because of the multidisciplinary nature of these systems and the collaboration of many different laboratories and organizations from vastly various fields with unequal types of equipment, it is essential to develop new techniques and materials to make the integration of disparate systems together more straightforward, accessible, and economical. In this paper, we present ethylene–vinyl acetate (EVA) as a new polymer-based material for the fabrication of different microfluidic chips,... 

Purpose: The prime end of this study was to design a novel pH-sensitive as well as a PEGylated dendritic nanocarrier for both controllable and traceable gemcitabine delivery to cancerous cells. To accomplish this goal, we took advantage of a hybrid of nanoparticles including: mesoporous silica, graphene oxide and magnetite. Methods: The nanocarrier was prepared in a multi-step synthesis route. First, magnetite mesoporous silica was deposited on the graphene oxide matrix. Then, polyamidoamine dendrimers (up to generation 1.5) with pentaethylene hexamine end groups were grafted on the surface of the nanoparticles. In order to enhance the biostability, and as the next step, the nanocarrier was... 

Let G be a graph whose each component has order at least 3. Let s: E(G) → Zk for some integer k≥ 2 be an improper edge coloring of G (where adjacent edges may be assigned the same color). If the induced vertex coloring c: V(G) → Zk defined by c(v)=∑e∈Evs(e)inZk, (where the indicated sum is computed in Zk and Ev denotes the set of all edges incident to v) results in a proper vertex coloring of G, then we refer to such a coloring as an improper twin k-edge coloring. The minimum k for which G has an improper twin k-edge coloring is called the improper twin chromatic index of G and is denoted by χit′(G). It is known that χit′(G)=χ(G), unless χ(G)≡2(mod4) and in this case χit′(G)∈{χ(G),χ(G)+1}.... 

Due to the high activity of Au nanoparticles (NPs) for various reactions, many researchers have tried to develop heterogeneous catalysts in order to prevent irreversible agglomeration of Au NPs. Herein, magnetic graphene oxide modified with polyaniline (PANI) was used as a support for Au NPs that brings together advantages including: uniform dispersal of the catalyst in water,alarge surface area related to the graphene oxide; easy electron transfer in chemical reactions and good attachment of Au NPs to the support associated with PANI; and finally facile recovery in the presence of a magnetic field. Catalytic reduction of different analytes (Congo red, methylene blue, rhodamine B and 4-nitro... 

A Non-rigid Air Flow Active Sensor (NAFAS) to detect the respiratory patterns is introduced in this paper. The main part of NAFAS is an ionic electroactive polymer-based ( ${i}$ -EAP) soft sensor. It can accurately detect breathing patterns and has promising features to develop low cost, wearable, and ubiquitous spirometers. Patients with respiratory diseases need to take pulmonary function tests consistently. Hence, it is time-consuming and expensive. To address these problems, NAFAS presents point-of-care testing (POCT) of the respiratory system's function. The proposed ${i}$ -EAP based sensor is a small strip of Ionic Polymer Metal Composite (IPMC) that has been fabricated using a Nafion... 

Actuator limitations hinder high-performance control of robotic manipulators. The problem is particularly challenging in case of underactuated robots where the issue has received less attention. In this brief, we investigate stabilization of manipulators under input constraints via total energy shaping. For this purpose, we use interconnection and damping assignment passivity-based control (IDA-PBC) together with an optimization technique to keep actuator torque close to allowable limits. Using a subsequent technique, the actuator torques are ensured to stay within the specified bounds for special classes of manipulators. The results are verified through simulations on a 2 degree-of-freedom... 

Wireless networks with the shared media require Medium Access Control (MAC) protocol that provides contention resolution mechanism. The design of MAC protocol in underwater sensor networks is a challenging issue because of limited energy source and high propagation delay. The most important goal of the MAC design for underwater sensor networks is to resolve data packet collision efficiently with respect to energy consumption. So, selection of MAC protocol is an important task because it has significant impact on the system efficiency. A suitable MAC protocol must consider some factors such as fairness, energy consumption, latency and throughput based on various applications. The bandwidth in... 

Clay liners are widely used as porous membrane barriers to control solute transport and to prevent the leakage of leachate both in horizontal and vertical flow scenarios, such as the isolated base and ramps of sanitary landfills. Despite the primary importance of saturated hydraulic conductivity in a reliable simulation of fluid flow through clay barriers, there is no model to predict hydraulic conductivity of clayey soils permeated with saline aqueous solutions because most of the current models were developed for pure water. Therefore, the main motivation behind this study is to derive semi-empirical models for simulating the hydraulic conductivity of clayey soils in the presence of... 

Solid waste is often buried in landfills isolated with a bentonite-based clay barrier to guarantee the high quality of groundwater. As the efficiency of clay barriers is highly dependent on solute concentration, this study aims to modify membrane efficiency, effective diffusion, and hydraulic conductivity of bentonite-based clayey barriers exposed to saline environments for numerical investigation of solute transport in such barriers. Therefore, the theoretical equations were modified as a function of solute concentration instead of constant values. First, a model was extended for membrane efficiency as a function of void ratio and solute concentration. Second, an apparent tortuosity model... 

Background and objective: L-Sorbose, as a precursor of ascorbic acid, can be biologically produced using Gluconobacter oxydans. The aim of this study was to optimize production of L-Sorbose by controlling concentration of the substrates and starter cultures. Material and methods: In this study, effects of three various fermentation parameters on the concentration of L-sorbose were assessed using fermenter (28°C, 1.4 vvm) and response surface methodology. These parameters included quantities of D-sorbitol (120-180 g lDw-1) (Deionized water) and yeast extract (6-18 g lDw-1) and inoculum/substrate ratios (5-10%). Results and conclusion: Results showed that the fitted model with high values of... 

This paper proposes an innovative robust-fuzzy method for multi-objective, multi-period supplier selection problem under multiple uncertainties. This approach integrates robust optimization and fuzzy programming. Uncertain parameters are modeled as random variables that take value within a symmetrical interval. However, due to the complexity or ambiguity of some real world problems and especially the nature of some of the available input data, the length of interval is also highly uncertain. This ambiguity motivated us to present a new approach, which could be applicable to multiple uncertainties conditions. Thus, in our approach, the half-length of these intervals is also represented by...