Sharif Digital Repository

Molecular nanomagnets, also known as Single Molecule Magnets (SMMs) are a class of molecules that at low temperature exhibit magnetic hysteresis of pure molecular origin and not related to a cooperative effect. In the past fifteen years they have attracted great interest for their potentiality to act as magnetic memory units and for the many quantum effects in the dynamics of their magnetization. Organization of SMM on surfaces is the first step in order to address the magnetic state of a single molecule or to connect the molecule to a conducting substrate. The complex nature of SMMs and the peculiar origin of their magnetic bistability have been representing for half a decade an obstacle to... 

Different disadvantages associated with using fossil fuels as the main energy source including crisis of wells’ depletion and serious environmental problems, causing by the emission of large quantities of greenhouse gases (GHG), especially carbon dioxide (CO2), has increased attention to replacing them with renewable and clean fuels such as wind, solar, and geothermal energy sources. Hydrogen, as a clean energy carrier, is one of the best fuels in terms of the environment and cost. So, it is recently receiving increasing attention and it may one day replace fossil fuels for various applications such as in automobiles and power stations. The main subject of this thesis was surveying the... 

In the present investigation, experimental design, synthesis and evaluation of Verapamil, Albumin, Immonuglubline G and Trypsin imprinted polymers and finally Albumin imprinted poly(dopamine) nano-layer were presented. A bimodal polymerization approach as a combination of precipitation and dispersion polymerization was taken towards producing 500 nm particles for verapamil imprinting purpose. In this case the imprinting factor was 2.17. In a challenge for producing spherical particles with predefined size and pore properties the hierarchical polymerization in packed beds, using porous silica particles (particle size ca. 40 µm) was developed, as well. The method resolving the problems... 

Hydrogen bonding is an important weak interaction encountered in gas, liquid, as well as solid phases. The hydrogen bond plays a very vital role in many life processes and is one of the most frequently used terms in chemistry and biology.
Polyols or polyhydric alcohols are, strictly speaking, simply organic chemicals containing more than two hydroxyl groups. Each hydroxyl is attached to separate carbon atoms of an aliphatic skeleton.They may also contain ester, ether, amide, acrylic, metal, metalloid and other functionalities; along with hydroxyl groups. Polyols are obtained from many plant and animal sources and are synthesized by a variety of methods. Among important properties of... 

the purpose of this research is to construct the facial image of a person from corresponding DNA. In this problem, we have a set of DNAs and facial images and we want to find the relation between the DNA and the features of facial images.using this relation we can find the facial Image of a person using the DNA. for this purpose we should first extract the features of faces that have the most variation among the population. by studying the feature extraction methods in this field, we borrow the deep neural network method that is used in face recognition fields.we found significant relations between DNA and extracted features from this network. finally using this relation we can predict the... 

Cancer diagnosis area has recently been in the limelight of the medical research and there exist an unremitting focus on the devices & technologies which enable cancer detection in its victims. Lately a genius diagnostic method based on isolation and entrapment of circulating tumor cells has been developed which pave the path for cancer identification. These circulating cells which are detached from the primary tumor are carried out through body by means of circulation system. They play key role in phenomenon called metastasis. Separating these rare cells from multifarious background blood cells, assessing their quantity can supply valuable information on the stage of disease as well as its... 

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... 

Conversion of Methane molecule to valuable heavier hydrocarbon and hydrogen by using of short pulse lasers is investigated. The dynamical information of molecule such as orientation, dipole moment variations with binding length, and potential energy levels are initially produced by using Gaussian software. Based on this information the Schrödinger wave equation for this polyatomic molecule is numerically solved. Then by selecting the various laser parameters and installing of them in the Hamiltonian of the mentioned system, the dependence of hydrogen transition and separation probability on these parameters are investigated. In this work by radiating of the laser beam along the C2 symmetry... 

Ionization probability of Cl2 molecule is studied by irradiation of 800 nm Ti: Sapphire laser pulses at intensities of 1014 Wcm-2 to 1016 Wcm-2 with the Gaussian package. Molecular orbital symmetry and orientation of the molecule dipole moment with laser field polarization axis are very effective in ionization probability. The results show that the most ionization probability for the intensity of 1014 wcm-2 is at 900 and also 50 at intensity of 1016 wcm-2. Due to the lack of intrinsic dipole moment, variation of dipole moment with the intensity, bond length and time evolution of dipole moment are investigated. It is found that there is a linear dependance of these parameters with ionization... 

The present research devoted to the application, development and implementation of clustering, classification and regression techniques for modeling of the biological activity of different drug and drug-like molecules. At first, the prediction ability of Bayesian regression techniques was evaluated for describing and predicting the inhibition behavior of Integrin antagonists. As a next step, the complementary local search techniques have been used for improving the performances of Bayesian regularized genetic neural network (BRGNN) algorithm. The results indicated that the pattern search algorithm has a great potential to be used as a feature selection method in Chemoinformatics. In line... 

This paper presents a scalable and ultrasensitive magnetic biosensing scheme based on on-chip LC resonance frequency-shifting. The sensor transducer gain is demonstrated as being location-dependent on the sensing surface and proportional to the local polarization magnetic field strength |B|2 generated by the sensing inductor. To improve the gain uniformity, a periodic coil is proposed as a substitution for the standard process coil. As an implementation example, the circuit is designed in a 65nm CMOS process. The spatially uniform sensor gain of the array is verified by COMSOL simulations. Overall, the presented sensor demonstrates an improvement in the uniformity of the inductor’s magnetic... 

This thesis is divided into three parts: In part I, conformational properties of neutral, anionic, cationic and zwitterionic forms of glutathione tripeptide were investigated by means of DFT-B3LYP method with 6-31+G (d,p) basis set. Results show that glutathione is a very flexible molecule and its conformational energy landscape is strongly influenced by forming intramolecular hydrogen bond and its charge. Conformation of each amino acid in glutathione tripeptide depends on its orientation within the peptide sequence in addition to the conformation of other amino acids within the chain. Investigation of intramolecular hydrogen bonds in these conformers by means of AIM analysis demonstrates... 

A general regularity has been found based on an effective pair potential of Lennard-Jones LJ (12, 6) for both dense nonmetallic and nonionic fluids and solids; namely, (Z-1)V2 linearly varies with respect to ρ2, this equation of state (EoS I) is known as LIR. The other equation of state (EoS II), according to wich the isotherm of (Z-1)V2 is linear in term of 1/ρ, wich gives a good description for the metallic and ionic fluids and solids. This equation of state was suggested based on an effective pair potential of LJ (6, 3). Unexpectedly, solid and liquid Ne indicates a significant deviations from EoS I. Recently, a general equation of state (EoS III) based on an effective near-neighbor pair... 

DNA is big protein molecule consisting of two strands intertwining each others. Recently DNA molecule has drawn attention of researchers to be used in electronic circuits and molecule electronic field. Therefore, many experiments have been carried out to measure DNA conductivity in different temperature in single molecule or bundle mode with varying size and shape. In this thesis, metallic bundle DNA at normal room temperature is studied and their resistance characteristic is obtained and compared. In order to improve DNA conductivity Metal Ions like zinc are adulterated to each of its structure period. DNAs with these metallic impurities are called metallic DNAs.
Thus, golden electrodes... 

Single molecule magnets due to their magnetic tunneling effect and the interaction they have with an external magnetic field are used widely in quantum computing and also the storage of data with high capacities. Polyoxometalates that are used as counter ions for cationic single molecule magnets, are able to affect their spin-couple nature via a magnetic exchange and also have an influence on the crystal accumulation in order to change the magnetic property of the molecule. In this research the probability of sedimenting a cationic single molecule magnet, [Mn4O2(CH3COO)7(bipy)2]+, with the use of anionic polyoxometalates with Keggin structures has been investigated. Thus, the single... 

Lipid membranes are fundamental constituents of cell membranes and are now used in lap-on-a-chip technology. Membranes in living cells contain a significant fraction of proteins, which undergo lateral random movements due to thermal fluctuations and shear forces imposed by the solvent fluid. Prominent natural and biotechnological systems where membranes are highly sheared include the plasma membrane of endothelial cells, and membranes used in biosensors for high throughput screening of drug candidates, and in water purification devices. In these systems membrane is in direct contact with the mainstream suspension flow, which is driven by pressure gradients. The efficiency and function of... 

Water transportation through carbon nanotubes is key for designing nanodevices. The directed transport of water molecules through a rotating charged carbon nanotube (CNT) is investigated by molecular dynamics simulations. It is found that the net flux of continuous unidirectional water flow depended sensitively on the charge distribution, charge density and rotation of the CNT. we find that for a constant charge density, the water flux increases with the increase of the charge difference. Besides, we find that the water flux shows a nonlinear dependence on the angular velocity of the rotation. The rotation of the CNT with low angular velocities, can not generate a continuous water flux. The... 

In recent decades the Due to development of coating techniques and the diversity of high organic matter, Discussion of organic coating materials being raised. Moreover, because of many applications of organic thin film in electronic and optical systems for example OTFTs and OLEDs Organic thin film growth topic is very interesting for scientists. Among these, some scientists study the theory and another bunch of scientists pay to practical aspects of this topic. In this thesis I pay to the theoretical level of Organic thin film growth and I simulate the system includes a collection of molecules, Went on to study some statistical properties of the system will be discussed and the dynamic... 

This thesis is divided into three parts: In part I, interactions of neutral and anionic forms of histidine with coinage metal nano clusters M3 (M = Au, Ag and Cu) are investigated. Results demonstrate that nonconventional M…H-O hydrogen bonds and M-X bonds (X = N, O) play stabilization roles in interactions of histidine and metal nano clusters. Presence of negative charge in ligand leads to increase of binding energy of complexes. In the next step, the effects of coinage metal nano clusters on the gas-phase acidity of weak organic acid (histidine) have been explored. The acidity of isolated histidine is compared with the acidity of its Au3–, Ag3– and Cu3–complexed species. Moreover, pKa... 

In this thesis, the molecular dynamics simulation is used to investigate the melting transition of B-DNA molecule, via of configurational entropy, the fraction of broken hydrogen bonds (f-curve) and hydrogen bonding energy.We have performed molecular dynamics simulation on Drew-Dickerson oligomer with sequence of (CGCGAATTGCGC) at different temperatures, within the range of 280-400 K with the 20 K intervals. The simulation was done in two different mediums (pure water and 1 M NaCl), to see influences of water and salt in stabilizing the DNA molecule. At each temperature, configurational entropy is calculated by the Schlitter’s formula, using the Cartesian coordinate of all atoms. So, in each...