Polynomial Structure of Topological String Partition Functions

We review the polynomial structure of the topological string partition functions as solutions to the holomorphic anomaly equations. We also explain the connection between the ring of propagators defined from special K\"ahler geometry and the ring of almost-holomorphic modular forms defined on modular curves.Comment: version 2: references fixe

MHD mixed convection flow in a vertical lid-driven square enclosure including a heat conducting horizontal circular cylinder with Joule heating

In the present numerical investigation we studied the effect of magnetohydrodynamic (MHD) mixed convection flow in a vertical lid-driven square enclosure including a heat conducting horizontal circular cylinder with Joule heating. The governing equations along with appropriate boundary conditions for the present problem are first transformed into a non-dimensional form and the resulting non linear system of partial differential equations are then solved numerically using Galerkin’s finite element method. Parametric studies of the fluid flow and heat transfer in the enclosure are performed for magnetic parameter (Hartmann number) Ha, Joule heating parameter J, Reynolds number Re and Richardson number Ri. The streamlines, isotherms, average Nusselt number at the hot wall and average temperature of the fluid in the enclosure are presented for the parameters. The numerical results indicated that the Hartmann number, Reynolds number and Richardson number have strong influence on the streamlines and isotherms. On the other hand, Joule heating parameter has little effect on the streamline and isotherm plots. Finally, the mentioned parameters have significant effect on average Nusselt number at the hot wall and average temperature of the fluid in the enclosure

Sinteza 1-acil-2-alkiltio-1,2,4-triazolobenzimidazola s antimikotskim, protuupalnim i analgetskim učinkom

Some new derivatives of 1,2,4-triazolo[2,3-a]benzimidazoles were synthesized through the reaction of 1,2-diaminobenzimidazole with carbon disulfide. The resulting 1,2,4-triazolo[2,3-a]benzimidazole-2-thione intermediate reacted with one equivalent of the appropriate respective alkyl halide to give the corresponding 2-alkylthio derivative 3a-g. The latters were acylated to afford the 1-acyl-2-alkylthio-1,2,4-triazolo[2,3-a]-benzimidazole derivatives 4-10 in good yields. Structures of the new compounds were verified on the basis of spectral and elemental methods of analyses. Fourteen of the prepared compounds were tested for their possible antifungal activities. Most of the tested compounds showed activity against Candida albicans and Fusarium oxysporum comparable to that of fluconazole as a reference drug. Compounds 8a, 9a, and 10d are the most active ones against most of the used fungi. Compounds 3e, 4d, 5d, 6d, 7d, 8c, 8d, 9d, and 10d were tested for their anti-inflammatory and analgesic effects; most of these compounds showed potent and significant results compared to indomethacin. Moreover, ulcerogenicity and the median lethal dose (LD50) of the most active compound 8d were determined in mice; LD50 was found to be 275 mg kg-1 (i.p.).Sintetizirani su novi derivati 1,2,4-triazolo[2,3-a]benzimidazola reakcijom 1,2-diaminobenzimidazola s ugljičnim disulfidom. Nastali 1,2,4-triazolo[2,3-a]benzimidazol-2-tioni reagiraju s jednim ekvivalentom odgovarajućeg alkil halida pri čemu nastaju 2-alkiltio derivati 3a-g. Acilacijom produkata 3 dobiveni su derivati 1-acil-2-alkiltio-1,2,4-triazolo[2,3-a]-benzimidazola 4-10 u dobrim iskorištenjima. Strukture novih spojeva potvrđene su spektroskopskim metodama i elementarnom analizom. Ispitivano je antimikotsko djelovanje 14 priređenih spojeva, uz flukonazol kao poredbenu tvar. Većina testiranih spojeva djeluje na Candida albicans i Fusarium oxysporum slično kao flukonazol. Najaktivniji su bili spojevi 8a, 9a i 10d. Produkti 3e, 4c, 5c, 6c, 7c, 8b, 8c, 9c i 10c ispitani su na protuupalno i analgetsko djelovanje, uz indometacin kao poredbenu tvar. Većina spojeva ima značajno djelovanje. Najaktivniji spoj testiran je na ulcerogenost. Srednja letalna doza (LD50) određena je na miševima i iznosi 275 mg kg-1 (i.p.)

Finite Element Analysis of Mixed Convection in a Rectangular Cavity with a Heat-Conducting Horizontal Circular Cylinder

. Combined free and forced convection in a two dimensional rectangular cavity with a uniform heat source applied on the right vertical wall is studied numerically. A circular heat conducting horizontal cylinder is placed somewhere within the cavity. The present study simulates a practical system, such as a conductive material in an inert atmosphere inside a furnace with a constant flow of gas from outside. Importance is placed on the influences of the configurations and physical properties of the cavity. The development mathematical model is governed by the coupled equations of continuity, momentum and energy and is solved by employing Galerkin weighted residual finite element method. In this paper, a finite element formulation for steadystate incompressible conjugate mixed convection and conduction flow is developed. The computations are carried out for wide ranges of the governing parameters, Reynolds number (Re), Richardson number (Ri), Prandtl number (Pr) and some physical parameters. The results indicate that both the heat transfer rate from the heated wall and the dimensionless temperature in the cavity strongly depend on the governing parameters and configurations of the system studied, such as size, location, thermal conductivity of the cylinder and the location of the inflow and outflow opening. Detailed results of the interaction between forced airstreams and the buoyancy-driven flow by the heat source are demonstrated by the distributions of streamlines, isotherms and heat transfer coefficient

Prandtl Number Effect on Assisted Convective Heat Transfer through a Solar Collector

Numerical study of the influence of Prandtl number on forced convective heat transfer through a riser pipe of a flat plate solar collector is done. The working fluid is Al2O3/water nanofluid. By Finite Element Method the governing partial differential equations are solved. The effect of the Prandtl number on the temperature and velocity field has been depicted. Comprehensive average Nusselt number, average bulk temperature, mean velocity, mid-height temperature inside the pipe, mean output temperature and collector efficiency are presented for the governing parameter mentioned above. Nu increases by 16% with the variation of Pr from 4.6 to 6.6 using nanofluid. Due to rising Pr heat transfer rate increases but collector efficiency devalues

Joule Heating Effect on the Coupling of Conduction with Magnetohydrodynamic Free Convection Flow from a Vertical Flat Plate

The present work describes the effect of magnetohydrodynamic (MHD) natural convection flow along a vertical flat plate with Joule heating and heat conduction. The governing boundary layer equations are first transformed into a non-dimensional form and resulting nonlinear system of partial differential equations are then solved numerically by using the implicit finite difference method with Keller box scheme. The results of the skin friction co-efficient, the surface temperature distribution, the velocity and the temperature profiles over the whole boundary layer are shown graphically for different values of the Prandtl number Pr (Pr = 1.74, 1.00, 0.72, 0.50, 0.10), the magnetic parameter M (M = 1.40, 0.90, 0.50, 0.10) and the Joule heating parameter J (J = 0.90, 0.70, 0.40, 0.20). Numerical values of the skin friction coefficients and surface temperature distributions for different values of Joule heating parameter have been presented in tabular form