Sharif Digital Repository

Sequential coloring of graphs was first introduced by Tucker in [Tucker (1983)] to study perfect graphs, and was subsequently studied from a number of different perspectives, such as its connections to uniquely colorable graphs. In this thesis we begin by introducing the version of sequential coloring of graphs defined by [Daneshgar and Ebrahimi (2008)], and after surveying their results concerning the defining sets of sequential coloring of graphs, and also surveying the results obtained by [Daneshgar, Rahimi and Taati (2010)] and [Daneshgar, Hajiabolhassan and Taati (2010)] regarding the simulation of functions using sequential coloring of graphs, we turn to the reduction systems that can... 

Sleep is vital for physical and mental health, affecting neurocognitive, physiological, and psychopathology functions and performance. Arousals are linked with sleep and interrupt the sleep states, forming a sleep/arousal loop. Spontaneous arousals are part of a normal sleep/wake cycle. There are also different clinical conditions causing sleep fragmentation and arousals, including sleep apnea (obstructive, central, and mixed apnea), hypopnea, and non-apnea such as respiratory effort-related arousals (RERA), snoring, teeth grinding, and periodic leg movement.This research introduced a novel approach for automatic arousal detection inspired by extracting respiratory information from EEG... 

In this work, wool keratin/polyethylene oxide (PEO) nanofibrous scaffolds were fabricated by electrospinning method. Bacterial cellulose nanofibrils (BCNFs) were embedded in the electrospun keratin/PEO nanofibers. Incorporation of BCNFs into the nanofibers enhances their hydrophilicity, mechanical properties and cell viability, adhesion and proliferation. Water contact angle of the nanofibers decreased from 126˚ to 83˚by addition of 1 wt % BCNFs. A thermogelling hydrogel based on carboxylated pluronic (Pl-COOH) and gum tragacanth (GT) was fabricated and polymer conjugation was confirmed by FTIR and H-NMR spectroscopy. Morphological and viscoelastic properties of GT-grafted Pl-COOH hydrogels... 

The X-ray attosecond pulses have many useful applications for studying atomic and sub-atomic scales phenomena in attosecond scale duration. Generation and optimization of high-order harmonics is an efficient way to produce such attosecond pulses which are studied in this thesis. There are several limitations in the attosecond pulse generation such as low efficiency of high-order harmonics, long duration of output pulses and the impossibility of producing an attosecond pulse with any desired wavelength in the x-ray region. Therefore, more investigations into high harmonic generation and fully control and optimization of this process is significant. In this thesis, high harmonic generation... 

Nitrite (〖NO〗_2^-) anions are ubiquitous within the physiological, industrial, environmental, and food industries. The potential toxicity risk of these inorganic compounds has well been recognized; thus, the precise detection of these ions by developing reliable and high-throughput analytical methods is crucial for health and environment security. In this study, we present a reagentless electrochemical biosensor using cobalt-based metal-organic frameworks (ZIF-67) and gold nanoparticles (Au NPs) for determination of nitrite ions. The developed biosensor provides the advantages of MOF properties including high surface area, hierarchical porosity, and tunable functionalities along with high... 

Today, the use of carbon nanostructures hybridized with noble metals has attracted considerable attention for the fabrication of bio-electrochemical sensors. Since the specific surface area has an immense effect on the sensing response, three-dimensional structures of graphene have a great capability to utilize in these sensors. In this research, three-dimensional graphene was provided on the porous nickel foam by chemical vapor deposition technique. By evaluation of raman spectroscopy, the time period of 20 minutes for solving of the carbon atoms into the nickel foam was selected as the main parameter of optimized conditions for the synthesis of graphene. Afterward, production of few-layer... 

A Brain-Computer Interface (BCI) is a communication system that does not need any peripheral muscular activity. The huge goal of BCI is to translate brain activity into a command for a computer. One of the most important topics in the brain-computer interface is motor imagery (MI), which shows the reconstruction of subjects. The electrical activities of the brain are measured as electroencephalogram (EEG). EEG signals behave as low to noise ratio also show the dynamic behaviors.In the present work, a novel approach has been employed which is based on feature extraction with discretion wavelet transform (DWT), support vector machine (SVM), Artificial Neural Network (ANN) and Convolutional... 

Tissue engineering has the potential to revolutionize our health care system. Conceptually, lost or malfunctioning tissues will be replaced by man-made biological substitutes to restore, maintain, or improve function. Tissue engineering has already shown great promise to contribute to treatments of a myriad of diseases including osteoarthritis, cancer, diabetes, skin burns, cardiovascular conditions and various traumatic injuries. Tissue engineering is a highly multidisciplinary discipline that demands integration of knowledge, tools and skills from biology, chemistry, engineering and medicine. Integrating nano- and microtechnologies into clinically sized implants represents a major... 

3D bioprinting is an additive manufacturing method that facilitates the deposition of the desired cells and biomaterials at any pre-defined location. This technique also enables control over the internal structure and external dimensions of printed constructs. Among various biomaterials used as bioinks, the bioinks derived from decellularized extracellular matrixes (dECMs) have attracted significant attention due to their bioactivity and being a rich source of biochemical cues. Here in this study, the decellularized amnion membrane (dAM) has been selected as the main component of the bioink formulation because of its biocompatibility, low immunogenicity, antibacterial property, abundance,... 

Treatment of critical-size bone defects caused by sport injuries, accidents, trauma, infection, and osteoporosis remains a major clinical challenge. In order to repair or regenerate large bone defects, bioactive three-dimensional scaffolds play a key role due to their multilevel porous structure, high surface area, enhanced mass transport and diffusion. Many studies reported that macropore diameters greater than 500 µm can lead to vascularized bone tissue. In this study, a hierarchically porous composite scaffold was prepared. Hierarchically porous silk fibroin- bioactive glass composite and fibroin scaffold were fabricated with controlled architecture and interconnected structure with...