Tameness of local cohomology of monomial ideals with respect to monomial prime ideals

In this paper we consider the local cohomology of monomial ideals with respect to monomial prime ideals and show that all these local cohomology modules are tame.     

A new two-step P-stable hybrid Obrechkoff method for the numerical integration of second-order IVPs

In this paper, we introduce a class of new P-stable hybrid Obrechkoff methods for the numerical solution of second-order initial value problems. We generate a two-step, symmetric, P-stable hybrid Obrechkoff method of order 8 with two off-step, symmetric, points and phase lag of order at least 2 and for special cases, this order can be increased up to 6. The numerical results obtained by the new method for some problems show its superiority in efficiency, accuracy and stability.     

Selective mono- to perarylations of tetrabromothiophene by a cyclobutene-1,2-diylbisimidazolium preligand

(Cyclobut-1-ene-1,2-diyl)bis(1-methylimidazolium)tetrafluoroborate is applied as preligand in palladium-catalyzed cross-coupling reactions starting from tetrabromothiophene for the synthesis of mono-, bi-, tri-, and tetraaryl-substituted thiophenes bearing up to four different aryl rings. A synthetic kit for preparations of nine different substitution patterns of arylated thiophenes is presented by application of only one single catalyst system. In agreement with DFT calculations, which predict energetically low rotational barriers in triaryl-3-bromothiophenes and tetraarylthiophenes, no NOE effects between adjacent aryl rings are detectable. The regioselectivity of their syntheses has therefore been elucidated by reduction of triaryl-3-bromothiophene to 2,3,5-triarylthiophene followed by HMBC, HSQC, and NOESY NMR measurements. Additionally, results of an X-ray single structure analysis are presented.     

Large deflection of flexible tapered functionally graded beam

In this paper the semi-analytical analyses of the flexible cantilever tapered functionally graded beam under combined inclined end loading and intermediate loading are studied.In order to derive the fully non-linear equations governing the non-linear deformation,a curvilinear coordinate system is introduced.A general non-linear second order differential equation that governs the shape of a deflected beam is derived based on the geometric nonlinearities,infinitesimal local displacements and local rotation concepts with remarkable physical properties of functionally graded materials.The solutions obtained from semi-analytical methods are numerically compared with the existing elliptic integral solution for the case of a flexible uniform cantilever functionally graded beam.The effects of taper ratio,inclined end load angle and material property gradient on large deflection of the beam are evaluated.The Adomian decomposition method will be useful toward the design of tapered functionally graded compliant mechanisms driven by smart actuators.     

Phase transition in a self-gravitating planar gas

We consider a gas of Newtonian self-gravitating particles in two-dimensional space, finding a phase transition, with a high temperature homogeneous phase and a low temperature clumped one. We argue that the system is described in terms of a gas with fractal behaviour.     

Rheological and Mechanical Characterization of Multi-Walled Carbon Nanotubes/Polypropylene Nanocomposites

The rheology and morphology of multi-walled carbon nanotube (MWNT)/polypropylene (PP) nanocomposites prepared via melt blending was investigated. The minor phase content of MWNT varied between 0.25 and 8 wt%. From morphological studies using a scanning electron microscopy technique a good dispersion of carbon nanotubes in the PP matrix was observed. The rheological studies were performed by a capillary rheometer, and mechanical properties of the nanocomposites were studied using a tensile and flexural tester. Both PP and its nanocomposites showed non-Newtonian behavior. At low shear rates the addition of MWNT content causes an increase in viscosity; however, viscosity is less sensitive to addition of MWNT content at higher shear rates. Flow activation energy for the nanocomposites was calculated using an Arrhenius type equation. From this calculation it was concluded that the temperature sensitivity of nanocomposites was increased by increasing of nanotube content. An increase in tensile and flexural moduli and Izod impact strength was also observed by increasing the MWNT content. From rheological and mechanical tests it was concluded that the mechanical and rheological percolation threshold is at 1.5 wt%.     

New Pool Boiling Heat Transfer in the Presence of Low-Frequency Vibrations Into a Vertical Cylindrical Heat Source

A vertical cylinder was applied as a heat source into a water pool; the vibrations were imposed into the heater with different heat fluxes, and the frequencies were adjusted at 10, 15, 20, and 25 Hz. An imaging system was employed to observe the produced bubbles around the cylindrical heat source. The results showed that the boiling heat transfer was enhanced under the vibrations with a shorter transient process, and the wall temperature also decreased. The best enhancement ratio was achieved at the frequency of 25 Hz and a heat flux value of 30 kW/m² as a consequence of imposed vibrations.     

Smarandache Vertices of the Graphs Associated to the Commutative Rings

Let R be a commutative ring with identity 1 ≠ 0. A nonzero element a in R is said to be a Smarandache zero-divisor if there exist three different nonzero elements x, y, and b (≠ a) in R such that ax = ab = by = 0, but xy ≠ 0. We will generalize this notion to the Smarandache vertex of an arbitrary simple graph and characterize the Smarandache zero-divisors of commutative rings (resp. with respect to an ideal) via their associated zero-divisor graphs. We illustrate them with examples and prove some interesting results about them.     

Rapid Determination of Phenolic Compounds in Water Samples: Development of a Paper‐based Nanobiosensor Modified with Functionalized Silica Nanoparticles and Potato Tissue

In this study, we present a fast, simple, low‐cost and disposable method for determination of phenolic content in water samples, using a paper based polyphenol oxidase biosensor. The propylamine functionalized silica nanoparticles was dropped onto a paper sheet. After drying at room temperature, the potato tissue extract including polyphenol oxidase was immobilized on the paper via physical and chemical adsorption. The modified paper was placed on the top of the graphite screen printed electrode. To construct of an electrochemical nanobiosensor, the electrochemical behavior of the modified electrode in different steps was investigated by cyclic voltammetry and electrochemical impedance spectroscopy methods. After being optimized the effective parameters, the changes in the biosensor electrochemical response vs. to the different concentrations of the substrate (phenol solution) were monitored by differential pulse voltammetry and amperometry methods. The linear relationships for phenol detection were obtained in the concentration ranges of 0.01–160 μM and 0.1–300 μM with a detection limit of 0.007 μM and 0.042 μM with DPV and amperometry methods, respectively. This method was successfully used in the voltammetric determination of the phenol content in the real samples, like the river water and the wastewater of wood factory.