Sharif Digital Repository

The aim of this work was to synthesize molecularly imprinted polymer-poly ethylene glycol-folic acid (MIP-PEG-FA) nanoparticles for use as a controlled release carrier for targeting delivery of paclitaxel (PTX) to cancer cells. MIP nanoparticles were synthesized by a mini-emulsion polymerization technique and then PEG-FA was conjugated to the surface of nanoparticles. Nanoparticles showed high drug loading and encapsulation efficiency, 15.6 ± 0.8 and 100%, respectively. The imprinting efficiency of MIPs was evaluated by binding experiments in human serum. Good selective binding and recognition were found in MIP nanoparticles. In vitro drug release studies showed that MIP-PEG-FA have a... 

Modern techniques for expanding stem cells play a substantial role in tissue engineering: the raw material that facilitates regeneration of damaged tissues and treats diseases. The environmental conditions and bioprocessing methods are the primary determinants of the rate of cultured stem cell proliferation. Bioceramic scaffolds made of calcium phosphate are effective substrates for optimal cell proliferation. The present study investigates the effects of two bioceramic scaffolds on proliferating cells in culture media. One scaffold was made of hydroxyapatite and the other was a mixture of hydroxyapatite and ferromagnetic material (Fe3O4 nanoparticles). Disk-shaped (10 mm × 2 mm) samples of... 

The morphology of endothelial cells (ECs) may be an indication for determining atheroprone sites. Until now, there has been no clinical imaging technique to visualize the morphology of ECs in the arteries. The present study introduces a computational technique for determining the morphology of ECs. This technique is a multiscale simulation consisting of the artery scale and the cell scale. The artery scale is a fluid-structure interaction simulation. The input for the artery scale is the geometry of the coronary artery, that is, the dynamic curvature of the artery due to the cardiac motion, blood flow, blood pressure, heart rate, and the mechanical properties of the blood and the arterial... 

Bias temperature instability (BTI) is known as one serious reliability concern in nanoscale technologies. BTI gradually increases the absolute value of threshold voltage (Vth) of MOS transistors. The main consequence of Vth shift of the SRAM cell transistors is the static noise margin (SNM) degradation. The SNM degradation of SRAM cells results in bit-flip occurrences due to transient faults and should be monitored accurately. This paper proposes a sensor called write current-based BTI sensor (WCBS) to assess the BTI-aging state of SRAM cells. The WCBS measures BTI-induced SNM degradation of SRAM cells by monitoring the maximum write current shifts due to BTI. The observations show that the... 

There are numerous functions for laser in modern implant dentistry including surface treatment, surface coating, and implant manufacturing. As laser application may potentially improve osseointegration of dental implants, we systematically reviewed the literature for in vitro biological responses to laser-modified or processed titanium dental implants. The literature was searched in PubMed, ISI Web, and Scopus, using keywords “titanium dental implants,” “laser,” “biocompatibility,” and their synonyms. After screening the 136 references obtained, 28 articles met the inclusion criteria. We found that Nd:YAG laser was the most commonly used lasers in the treatment or processing of titanium... 

Conjugated Linoleic Acid (CLA) was produced from castor oil using washed cells of Lactobacillus plantarum PTCC 1058 and Lactobacillus plantarum subsp. plantarum PTCC1745 as the catalyst. Under the optimal reaction conditions, the washed cells of Lactobacillus plantarum PTCC1058 produced 1661.26 mg of CLA/L reaction mixture (36% yield of production) from 4.6 mg/ml of castor oil after using 15% (w/v) cell for 121 h. The resulting CLA was a mixture of two CLA isomers, cis-9, trans-11 (or trans-9, cis-11)-octadecadienoic acid (CLA1, 44% of total CLA) and trans-10, cis-12-octadecadienoic acid (CLA2, 46% of total CLA). The total production of CLA is extracellular in all of the reactions performed... 

Nowadays, nanoparticles (NPs) are used in a variety of biomedical applications including brain disease diagnostics and subsequent treatments. Among the various types of NPs, magnetic nanoparticles (MNPs) have been implemented by many research groups for an array of life science applications. In this paper, we studied MNPs controlled delivery into the endothelial cells using a magnetic field. Dynamics equations of MNPs were defined in the continuous domain using control theory methods and were applied to crossing the cell membrane. This study, dedicated to clinical and biomedical research applications, offers a guideline for the generation of a magnetic field required for the delivery of... 

Biocompatible porous polymeric scaffolds provide a suitable environment for proliferation of stem cells in human body. In this research work, porous gelatin–poly(ethylene glycol), PEG, based scaffolds were prepared using combination of freeze-gelation and freeze-extraction methods. Effects of various parameters such as freezing temperature, cross-linking agent, concentrations of gelatin and PEG and their blending ratio on physical and mechanical properties, swelling ratio, porosity, pore size, and degradation rate of scaffolds were investigated. Also, proliferation of fibroblast skin cells on the scaffolds was examined by MTS assay to assess the suitability of the scaffolds in wound healing... 

Interaction between intracellular dynamics and extracellular matrix (ECM) generally occurred into very thin fragment of moving cell, namely lamellipodia, enables all movable cells to crawl on ECM. In fast-moving cells such as fish Keratocytes, Lamellipodia including most cell area finds a fan-like shape during migration, with a variety of aspect ratio function of fish type. In this work, our purpose is to present a novel and more complete two-dimensional continuum mathematical model of actomyosin-cytosolic two-phase flow of a self-deforming Keratocyte with circular spreaded to steady fan-like shape. In the new approach, in addition to the two-phase flow of the F-actin and cytosol, the... 

Fast and accurate fault detection is the primary step and one of the most important tasks in fault tolerant converters. In this paper, a fast and simple method is proposed to detect and diagnosis the faulty cell in a cascaded H-bridge multilevel inverter under a short circuit fault. In this method, the reference voltage is calculated using switching control pulses and DC-Link voltages. The comparison result of the output voltage and the reference voltage is used in conjunction with active cell pulses to detect the faulty cell. To achieve this goal, the cell which is active when the Fault signal turns to “0” is detected as the faulty cell. Furthermore, consideration of generating the active... 

In this article, two soft error tolerant SRAM cells, the so-called RATF1 and RATF2, are proposed and evaluated. The proposed radiation hardened SRAM cells are capable of fully tolerating single event upsets (SEUs). Moreover, they show a high degree of robustness against single event multiple upsets (SEMUs). Over the previous SRAM cells, RATF1 and RATF2 offer lower area and power overhead. The Hspice simulation results through comparison with some prominent and state-of-the-art soft error tolerant SRAM cells show that our proposed robust SRAM cells have smaller area overhead (RAFT1 offers 58% smaller area than DICE), lower power delay product (RATF1 offers 231.33% and RATF2 offers 74.75%... 

Photovoltaic (PV) arrays are composed of PV cells which have a nonlinear power-voltage characteristic. To extract maximum amount of energy from a PV array, it is essential to track maximum power point (MPP). When all PV cells are subject to the same solar energy, MPP is found easily. However, in some ambient conditions, PV cells are partially or completely shadowed. Under partial shading conditions (PSCs), overall power-voltage curve will have several peaks. This paper presents a novel approach for MPP tracking, utilizing configuration of PV cells in series and parallel that may deliver maximum power in shading conditions. As such, instead of blindly searching for the global MPP among local... 

Producing mature and functional cardiomyocytes (CMs) by in vitro differentiation of induced pluripotent stem cells (iPSCs) using only biochemical cues is challenging. To mimic the biophysical and biomechanical complexity of the native in vivo environment during the differentiation and maturation process, polydimethylsiloxane substrates with 3D topography at the micrometer and sub-micrometer levels are developed and used as cell-culture substrates. The results show that while cylindrical patterns on the substrates resembling mature CMs enhance the maturation of iPSC-derived CMs, sub-micrometer-level topographical features derived by imprinting primary human CMs further accelerate both the... 

High rates of mortality and morbidity stemming from cardiovascular diseases unveil extreme limitations in current therapies despite enormous advances in medical and pharmaceutical sciences. Following myocardial infarction (MI), parts of myocardium undergo irreversible remodeling and is substituted by a scar tissue which eventually leads to heart failure (HF). To address this issue, cardiac patches have been utilized to initiate myocardial regeneration. In this study, a porous cardiac patch is fabricated using a mixture of decellularized myocardium extracellular matrix (ECM) and chitosan (CS). Results of rheological measurements, SEM, biodegradation test, and MTT assay showed that the... 

This paper presents a robust and low-power single-ended robust 11T near-threshold SRAM cell in 10-nm FinFET technology. The proposed cell eliminates write disturbance and enhances write performance by disconnecting the path between cross-coupled inverters during the write operation. FinFETs suffer from width quantization, and SRAM performance is highly dependent to transistors sizing. The proposed structure with minimum sized tri-gate FinFETs operates without failure under major process variations. In addition, read disturbance is reduced by isolating the storage nodes during the read operations. To reduce power consumption this cell uses only one bit-line for both read and write operations.... 

Optical tweezers are proven indispensable single-cell micro-manipulation and mechanical phenotyping tools. In this study, we have used optical tweezers for measuring the viscoelastic properties of human red blood cells (RBCs). Comparison of the viscoelastic features of the healthy fresh and atorvastatin treated cells revealed that the drug softens the cells. Using a simple modeling approach, we proposed a molecular model that explains the drug-induced softening of the RBC membrane. Our results suggest that direct interactions between the drug and cytoskeletal components underlie the drug-induced softening of the cells. © 2018 Optical Society of America  

Phase Change Memory (PCM) is one of the most promising candidates to be used at the main memory level of the memory hierarchy due to poor scalability, considerable leakage power, and high cost/bit of DRAM. PCM is a new resistive memory that is capable of storing data based on resistance values. The wide resistance range of PCM allows for storing multiple bits per cell (MLC) rather than a single bit per cell (SLC). Unfortunately, higher density of MLC PCM comes at the expense of longer read/write latency, higher soft error rate, higher energy consumption, and earlier wearout compared to the SLC PCM. Some studies suggest removing the most error-prone level to mitigate soft error and write... 

In this study, nanostructured biodegradable pure Zn, Zn-4 wt. % Mn and Zn-24 wt % Mn alloys were produced by 20 h mechanical alloying and consequent cold pressing and sintering. Structural evolutions were investigated using the X-ray diffraction technique. Also, the microstructure was characterized by scanning electron microscopy. The effects of alloy composition on density, mechanical properties, corrosion behavior in Hank's solution, cell viability and cell attachment were investigated. Crystallite size of the synthesized alloys after 20 h of milling reached to less than 40 nm and remained less than 80 nm after consolidation and sintering for 1 h. Alloys contain MnZn13 as second phase... 

Aluminum reduction cells have benefited from point feeding technology for a long time, but there are still smelters which are using the old technology of center break and center feed system. Due to several factors this system is no longer approved and there have been a few attempts worldwide to upgrade these cells so as to implement the newer technology by applying mechanical and automation changes. In this paper we will present an attempt which was made in order to retrofit a so-called center break cell to point feeder cell. The results show that this project has decreased the energy consumption and anode effect frequency. Furthermore, there has been a significant increase in current... 

Asphaltene precipitation is known to be responsible for serious challenges in oil industry such as wellbore damage, oil flow reduction, and plugging of transportation lines. The traditional methods to remove asphaltene deposition are mostly based on chemical solvent. One of the recent proposed green and cost–effect remedial methods is the application of microorganisms capable of consuming the heavy hydrocarbon chains. The cell surface hydrophobicity among others effectively manipulates the efficiency of the microorganism for asphaltene degradation. Besides, surface active agents would affect the microorganism adhesion and cell surface properties, and alters its hydrophobicity. Investigating...