Archives-June... 

Hexane, diethyl ether, dichloromethane and ethyl acetate extracts of twenty five plant species, including fourteen varieties of leaves, five varieties of whole plants, two varieties of barks and one variety of flower, fruit, seed and root were tested for ovicidal activity against Culex quinquefasciatus at 1000 ppm. During preliminary screening, significant ovicidal activity was observed in all four solvent extracts of Cleistanthus collinus, Hydrocotyle javanica, Leucas aspera, Murraya koeingii, Sphaeranthus indicus and Zanthophyllus limonella.  Solvent crude extracts of plants showing maximum ovicidal activity were selected and treated at 500 ppm. The percentage of egg hatchability significantly reduced in different solvent extracts of above mentioned plants and eggs treated with different plant extracts varied from 26.59 per cent  in diethyl ether extract of Murraya koeingii  to 82.61 per cent in hexane extract of Leucas aspera.

In this paper we apply Double A booth transform to solve the general linear telegraph equation. The applicability of this new transform is demonstrated using some functions.

Motivation plays an indispensable role in learning. Though motivation has got a lot of attention in literature of language learning, demotivation has not got much attention in general and particularly in Iranian EFL context. As Dörnyei (2001: p. 5) postulates "Demotivation is a salient phenomenon in L2 learning" and "much further research is needed to do this important motivational factor justice". The aim of the present study is to find out what the main demotivating factors in speaking skills among gifted students at SAMPAD schools are. In order to achieve this goal, 571 students who are secondary students in SAMPAD schools in Tehran were selected. The sampling was convenient sampling, and both male and female students participated in this study. A questioner which was validated and reliable was distributed among participants, and 68 students were interviewed. The findings of both quantitative and qualitative data reveal that five demotivating factors hindering learners in speaking classes are, teacher, material and content, facilities, attitude and teaching learning context. The findings can be applied for teacher development courses in which mentors can shed light on the importance of motivational factors in EFL classes. Key Words: motivation, demotivation, speaking skills, exceptionally talented students

The emerging Cognitive Technology promises to improve the network spectrum-utilization efficiency by allowing cognitive secondary users (SUs) to intelligently sense and opportunistically access those spectrum holes temporarily unused by license-holding primary users (PUs). Cognitive radios hold tremendous promise for increasing spectral efficiency in wireless systems. In this paper, we propose a cooperative spectrum sharing scheme between cellular network downlink and mobile ad-hoc network based on the analysis using stochastic geometry theory. The licensed spectrum belongs to the cellular network and the strong interference at cell-edge becomes a bottleneck to guarantee the quality of service requirement. In this case, the secondary ad-hoc users can assist the transmission between the base station and cell-edge mobile users in exchange for spectrum usage. Through maximizing the transmission capacity of secondary system under the constraint of throughput improvement of primary system, an optimal spectrum allocation can be obtained. Numerical and simulation results are provided to validate the analysis and verify the efficiency of the proposed scheme.

In this paper we have reported the Stokes Parameters of excited Magnesium atom using non-relativistic (DW) and relativistic distorted wave approximation theories (RDW) at incident electron energies 15 and 45 eV. Good agreement has been found on comparison of both DW and RDW methods with each other and the importance of relativistic effect is also explored.

Vehicular Ad Hoc Networks (VANET) is a subclass of Mobile ad hoc networks which provides a distinguished approach for Intelligent Transport System (ITS). The survey of routing protocols in VANET is important and necessary for smart ITS. This paper discusses the advantages / disadvantages and the applications of various routing protocols for vehicular ad hoc networks. It explores the motivation behind the designed, and traces the evolution of these routing protocols. This paper discusses the main 5 types of protocols for VANET Topology Based, Positioned Based, Geo Cast, Broad Cast, Cluster Based Protocols.

The crystal structure of the new complex [Cu(C5H7N3O)4]Cl2.5H2O has been determined by single crystal X-ray diffraction, and the compound was characterized by infrared spectroscopy and thermal analysis. The compound crystallizes in the monoclinic space group P21/c with lattice parameters a = 15.304(4), b = 13.528(3), c = 15.071(4) Å, ? = 90.120 (5)°, V = 3120.0 (13) Å3, and Z = 4. The solid state structure exhibits pronounced pseudosymmetry emulating an orthorhombic Pccn setting which is broken only by ordering of solvate water and chlorine anions in channels stretching along the c-axis of the unit cell. Structural and IR data indicate that the title compound is present as the keto tautomer 2-amino-6-methylpyrimidin-4-(1H)-one rather than in the enol form 2-amino-6-methyl-4-pyrimidinol. The Cu(II) atoms are four-coordinated in a square planar fashion by nitrogen atoms of four 2-amino-6-methylpyrimidin-4-(1H)-one ligands. The crystal structure is stabilized by O–H•••O, N–H•••O, N–H•••Cl and O–H•••Cl hydrogen bonds with pillars of the cationic complexes alternating with channels occupied by the chlorine anions and water molecules.

Two step austempering of ductile produces unique microstructure with excellent properties like high strength, toughness, good wear resistance, machinability at low cost. ADI primarily used in high stress machine parts, gears, crankshafts. Attempt is made to study the effect of austempering time and temperature on tensile behavior of ADI. ADI yielded from two step austempering process higher ultimate yield strength with almost no change in ductility. Mode of fracture changes from brittle to ductile with increased austempering time.

The molten salt electrolytes from which the polyvalent active metals are extracted are strongly structured at unusually long distances that increase the energy consumption of the electrowinning cell. Under influence of strong electrical pulses they are transferred to a non-equilibrium state with modification of the structure and intensification of electrochemical properties. The observed regularities in the electrolytes activation are due to stimulated dissociation of complex ions on the simpler and more mobile complex and elementary ions. This is confirmed by the disappearance of characteristic Raman peaks when the melts are activated. During the relaxation process in the non-equilibrium melts their electrochemical parameters and Raman peaks are seeking to recover their equilibrium values and pattern. All the observed regularities of the duration and the dynamics of the relaxation in non-equilibrium melts show that we definitely have deal with the structural relaxation in ionic.

The effects of dewaxing on the physico-chemical properties of some brands of vegetable oil have been investigated. Five (5) brands of crude vegetable oil including soybean oil (SO), beniseed oil (BO),cottonseed oil (CSO) and palm kernel oil (PKO) were used for these investigations. The physico-chemical properties and the wax contents were determined before and after the dewaxing operation. The wax contents (ppm), saponification numbers, % free fatty acid contents, slip melting points (0C) of the oil samples were reduced while the iodine values of the oil samples increased after the dewaxing operation. The dewaxed oil samples showed good abilities to withstand refrigerator temperature.