بهزاد خلیلی

Properties of the ionic liquids can be controlled by using different combinations of the cations and anions for specific purposes. In this work, density functional theory has been used at M06-2X/6-311++G(2d,2p) level of theory to investigate the effect of different substitutions on the electrochemical, physical and chemical properties of the pyridinium-based ionic liquids including 4X-Dimethylpyridinium cations ([4X-DMPy]+, X: NH2, OMe, Me, H, Cl, CHO, CF3, CN and NO2) and tetrafluoroborate anion ([BF4]-). Cathodic potential limit and anodic potential limit, electrochemical window, charge transfer values, structural parameters and topological properties of the ionic liquids were calculated. The results show that the strength of the interaction between the cations and anion increases with the increase in the electron withdrawing strength of the substituents on the 4 position of the pyridinium cation ring. According to the calculated interaction energies (from -104.71 to -90.59 kcal/mol), the stability of the studied ionic liquids is as follows: [NO2-DMPy][BF4] > [CN-DMPy][BF4] > [CF3-DMPy][BF4] > [CHO- DMPy][BF4] > [Cl-DMPy][BF4] > [H-DMPy][BF4] > [Me-DMPy][BF4] > [OMe-DMPy][BF4] > [NH2-DMPy][BF4]. Comparing the charge of the atoms from natural bond orbital analysis show that hydrogen bonding in the designed ionic liquids is accompanied by some charge transfer from anion to the cations, and the charge transfer for electron-withdrawing substituents (CHO) is greater than other substituents in [4X-DMPy][BF4] ionic liquids. According to the electrochemical window values of the studied ionic liquids (from 2.73 to 4.32 V), it is predicted that the ionic liquids containing electron-donating substituents are more suitable electrolytes than other ionic liquids in electrochemical reactions.

Labyrinth weirs are often a desirable design option to regulate upstream water elevations and increase flow capacity and the gate structures have some advantages including passing the floating substances and the sediments in using combined weir-gate structure. But, it can be difficult to design due to the complex flow characteristics of a labyrinth weir-gate. A labyrinth weir could be described as a continuous and broken weir plan in a trapezoidal or triangular form. Thus, for a fixed width, labyrinth weirs have a longer crest distance when compared to linear one. Most weirs create a relatively static water zone in their upstream, which can be the site for sedimentation and waste materials, which is a disadvantage of these structures. Because of the sediments deposition in upstream of the weirs the flow conditions change and the accuracy of the presented relationships is reduced. Although numerous methods of design have been published for labyrinth weirs, there is insufficient design information available about the combined models of Labyrinth weir-gate.

This study was conducted to improve labyrinth weir -gate design and analyses techniques using physical-model-based data sets. The experiments were conducted in a metal and glass flume with a rectangular cross-section. The flume was 0.25 m wide, 0.5 m deep, and 10 m long. In each test the upstream subcritical depth was measured using point gauges of 0.1 mm accuracy The location for measuring the total head of the water upstream of the weir is a horizontal distance of three to four times the maximum water head on the crest of the weir. The discharge was measured with a triangle sharp weir placed at the end of the flume. The discharge-head relationship (Q-h) for triangular weir in experiments is as Q=0.6918 h2.5. The trapezoidal labyrinth weir-gate models was installed at the distance of 3 m of the beginning of flume. The base material roughness was made of natural sand with a mean diameter of 3 mm. In this research, experimental study of combined flow trapezoidal labyrinth weir-gate with one cycle has done for three sidewall angles of 15, 20 and 25 degrees, three gate openings 2, 4 and 6 cm and the weir height of 14 cm in a rectangular channel. According to the effective parameters of the combined models including sidewall angel (), gate opening (a) and the hydraulic head (Ht), the discharge coefficient has evaluated. By applying the Buckingham π theorem an equation was obtained. The discharge coefficient of trapezoidal labyrinth weir-gate can be expressed as a function of the variables of Fr,Re,We,H_t/P,L/H_t ,H_t/a,ϕ,α. In this study, the depth of water measured on the weir crest is at least 3 cm, so the effect of surface tension on the weir (We) is negligible. The effect of dynamic viscosity on the hydraulic behavior of the flow can be ignored. Therefore, the Reynolds number (Re) can be removed.

The results show that the discharge coefficient decreases with increasing the ratio of Ht/P for both smooth and rough beds and it reaches a constant discharge coefficient for Ht/P >0.6. According to the effective parameters of the combined models, the discharge coefficient has obtained averagely in the range of 0.61-0.75. The discharge coefficient of the combined flow increases with increasing angle of the weir. The increase in discharge coefficient is due to the decrease in the length of weir which decreases the flow mixing. Also for a specified angle, the discharge coefficient increases with increasing of L/ Ht then gets a constant value. The effects of artificial roughness on discharge capacity are also presented. It can be shown that the discharge coefficient increases in rough bed condition compared to the smooth bed condition. The present test data and those of Crookston (2010) were compared and it can be seen that the discharge coefficient in combined flow trapezoidal labyrinth weir-gate is more than the discharge coefficient of the trapezoidal labyrinth weir (without gate) in Crookston (2010) investigation.

The discharge coefficient of trapezoidal labyrinth weir-gate has the highest value for weirs with a sidewall angle of 25° and gate opening of 6 cm in rough bed condition about 17% more than the smooth bed. Among the different experimental models with a sidewall angle of 25, the labyrinth weir-gate in the rough bed condition has the highest discharge coefficient (approximately 0.93) compared to the smooth bed (approximately 0.61).

In this review paper, a systematic study on the physical adsorption of ionic liquids with different cations, investigation of molecular interactions between cations and anions of tunable ionic liquids, study of different nanostructures based on graphene, silicon, germanium and boron-nitride without defects and comparison of stability between types of nanostructures and creating defects on them (pore defects and Stone Walls) and studying the effect of changes in the absorption of ionic liquids on different nanostructures without defects and defects on physical properties such as: bond energy, interaction energy, energy gap, chemical hardness, chemical potential and absorption spectra have been performed.

This research represents a theoretical study on the ligands derived from O-phenylenediamine and salicylaldehyde and their complexes with Zn2+ using B3LYP/6-311++G(d,p) and M06-2X/6-311++G(d,p) computational levels. the effect of substituents on the electronic and physicochemical properties of the thirteen complexes obtained with various electron-donating and electron- withdrawing substituted schiff base ( X: NO2, NH2, OCH3, H, F, Cl, Br, CN, OH, N(Me)2, CHO, CH3, CF3) and Zinc cation was investigated. The amounts of the charge transfer, interaction energy, formation enthalpy, Gibbs free energy, structural parameters and geometric properties were perdicted. The result show that the interaction between Zn2+ and ligands increases with the increase of electron-donating nature of substituents on the para position of the phenolic ring of the ligands. Since B3LYP resulted in more accurate results in comparison with M06-2X, then the B3LYP method was applied to the next calculations (NBO, AIM). According to the calculated interaction energies, the order of stability of the complexes was found to be as follows: LN(Me)2Zn > LNH2Zn > LOCH3Zn > LCH3Zn > LOHZn > LHZn> LBrZn > LClZn > LFZn > LCHOZn > LCF3Zn > LCNZn> LNO2Zn.

In this work, a new sulfamic acid-based catalyst that could be used in the solid phase was synthesized using chlorosulfonic acid and methylene dianiline in a simple manner. The structure of the catalyst was characterized, and then it was used as a catalyst in the synthesis of biologically active xanthene derivatives to the evaluation of its efficiency. The mentioned catalyst showed better catalytic activity than the other reported ones from the points of simple using at solid phase and being free of environmental pollutant halogens. The results verified its capability for improving the reactions, which usually need an acidic catalyst to perform. Finally, bis(xanthenes) are synthesized using this catalyst for the first time in good yields. The structures of the new compounds were verified using FT-IR, H-NMR, and C-NMR spectroscopies.

The combined weir- gate is important hydraulic structure in management of irrigation canals. On the other hand, the use of labyrinth weirs can reduce water level fluctuations due to longer crest lengths than linear weirs for a specific discharge. Because of the sediments deposition in upstream of the weirs the flow conditions change and the accuracy of the presented relationship is reduced. Therefore, the use of combined flow trapezoidal labyrinth weir-gate can be a useful solution for passage of floating substances over the weir and sediment transport under the gate. In this research, experimental study of combined flow trapezoidal labyrinth weir-gate with one cycle has done for three sidewall angles of 15, 20 and 25 degrees, three gate openings 2, 4 and 6 cm and three weir heights of 14 , 17 and 20 cm in a rectangular channel. Based on the effective parameters of the combined models, the mean discharge coefficient has obtained in the range of 0.61-0.75. The results show that the discharge coefficient decreases with increasing the ratio of Ht/P, and it reaches a constant discharge coefficient of 0.61 for Ht/P >0.6. The discharge coefficient of the combined model increases by increasing the angle of the weir. Also the results show that the discharge coefficient of trapezoidal labyrinth weir-gate has the highest value for weirs with a sidewall angle of 25 ° and gate opening of 2 cm.

A simple, efficient and versatile procedure for the synthesis of the 1-Aryl-1H-tetrazols using reaction between triethyl orthoformate, sodium azid and aryl amines in the presence of the ZrOCl2.8H2O as catalyst is introduced. The reaction is carried out at acetic acid as solvent under low temperature and gets pure products in high yields. In continue the quantum chemical computations were done on products using density functional theory. The M062X/6-31G(d) used as the method and basis set for all calculations. Geometrical structures, thermodynamical properties, frontier molecular orbitals (HOMO and LUMO) and electrostatic potential maps of the products were obtained and analyzed. The results showed that the both of the maximum and minimum electrostatic potential regions are located on the tetrazol ring therefore for both of the nucleophilic and electrophilic reactions the tetrazol ring will be prior to the phenyl one.

In order to reducing spillways construction costs, using Spillway with Converging Walls is cost effective and appropriate solution. Although the use of these type of spillways growing, most studies do not consider effects of the converging walls on flow pattern and structural performance of the spillway. In this study, Flow-3D software and RNG Turbulence model used for numerical simulation of the flow. CATIA software is used to define the geometry of the solid boundaries. A computational block consists of 4000000 calculations used to separating the flow field. In order to verify the numerical model, at first the results of numerical model compared with results of Gavshan dam physical model and after ensuring the accuracy of the numerical model, the effect of Gavshan dam spillway constriction on hydraulic characteristics of the flow modeled with angles of shrinkage 0, 1, 2.5, and 3 in addition to the two-degree angle, which is used in the design of the Gavshan dam, and evaluated for three flow rates of 600, 950, and 1350 cubic meters per second.

One-pot synthesis of 3-substituted coumarins using Red mud (RM) which emerges as a by-product from the alumina producing process as a catalyst via Knoevenagel condensation of 2-hydroxybenzaldehyde derivatives and malonate derivatives are investigated. Reaction carried out under various conditions and the best results are obtained when the reaction is done under microwave irradiation. RM showed an efficient catalytic activity in this reaction. The catalyst can be used for at least four times after reactivation without remarkable losing in its efficiency. Finally, some of the thermochemical properties such as enthalpy and Gibbs free energy of formation for the synthesized coumarins are calculated using quantum chemistry, and also an electrostatic potential map of some of the synthesized coumarins was obtained using computational chemistry software which could be so helpful for the analysis of active reaction sites of coumarins.

Heterocyclic compounds containing two heteroatoms in the structure are well known molecules with diverse biologically activities. Among them, thiazoles, thiazolidines, thiazolidinones and thiazolones are the most important scaffolds associated in the structure of many naturally occurring biological active compounds. A simple and efficient procedure for the synthesis of 4-arylidene-2-alkylthio-4H-thiazol-5-ones, the thia analogue of azlactones, via the condensation reaction of an aldehyde with an amino acid based dithiocarbamate is described. Also the bis [2-(alkylthio)-thioazlactone] was prepared using terephthaldehyde. High to excellent yields of products, simple reaction procedure and synthesis of complex molecules with simple starting materials are the most advantages of this protocol.