Computer-simulation analysis of the ESR spectra of mechanoradicals in PMMA

In this study, initially, we tried to obtain the mechanoradicals of PMMA (poly(methyl methacrylate)). For this purpose, we designed a simple drilling apparatus. Using this apparatus, we prepared some PMMA samples at 77 K in vacuum. Later, by using an ESR (electron spin resonance spectrometer), we observed ESR signals for these samples at 77 K. This means that mechanoradicals have been successfully produced by mechanical fracture in PMMA using our drilling apparatus. Secondly, we tried to identify the radicals from these spectra through using theoretical analyses and, some computer simulations have been done by suggesting two different theoretical models for these ESR signals. Finally, by using experimental and theoretical data, we showed that our simple apparatus could be used to obtain mechanoradicals from polymers. Results were seen to be in very good agreement with the literature. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 2195–2200, 1997     

Møller Energy-Momentum Distribution of Higher Dimensional Vaidya Space-Time

In this paper, we intend to clarify the energy-momentum problem of higher dimensional Vaidya space-time in the general theory of relativity. In this connection, Møller energy and momentum for the higher dimensional Vaidya space-time are evaluated in the frame of general relativity. We have obtained that the Møller energy distribution of higher dimensional Vaidya space-time is equal to zero, while the Møller momentum distribution of higher dimensional Vaidya space-time is not equal to zero.     

Viscoelastic Timoshenko Beams with Occasionally Constant Relaxation Functions

For a prescribed desirable arbitrary decay suitable viscoelastic materials are determined through their relaxation functions. It is shown that if we wish to have a decay of order ??(t) then the kernels should be of the same order. That is their product with this function should be summable.     

On a non-dissipative Kirchhoff viscoelastic problem

In this paper we consider a Kirchhoff type viscoelastic problem, and prove uniform stability of the system. We do not rely on the dissipativity of the system or the boundedness of the energy as in the previous treatments. There appears a quadratic term which we cannot estimate by the initial energy as our system is not clearly dissipative in advance.     

A New Class of Kernels Leading to an Arbitrary Decay in Viscoelasticity

A new assumption on the relaxation in a viscoelastic problem ensuring uniform stability in an arbitrary rate is established. This assumption replaces a usual condition and allows for a much wider class of kernels. As consequences several earlier results are extended and improved.     

Length 3 complexes of abelian sheaves and Picard 2-stacks

We define a tricategory T[−2,0] of length 3 complexes of abelian sheaves, whose hom-bigroupoids consist of weak morphisms of such complexes. We also define a 3-category 2Pic(S) of Picard 2-stacks, whose hom-2-groupoids consist of additive 2-functors. We prove that these categories are triequivalent as tricategories. As a consequence we obtain a generalization of Deligne's analogous result about Picard stacks in SGA4, Exposé XVIII (Deligne (1973) [11]).     

Nonexistence of Global Solutions of Some Quasilinear Hyperbolic Equations with Dynamic Boundary Conditions

In this paper the non-existence of global solutions of two fourth-order hyperbolic equations with dynamic boundary conditions is considered. The method of proof makes use of the generalized convexity method due to Ladyzhenskaya and Kalantarov [4].     

Raman characterizations and structural properties of the binary TeO2?WO3, TeO2?CdF2 and ternary TeO2?CdF2?WO3 glasses

The Raman spectroscopy technique was used to characterize the microstructure and the crystallization properties of the as‐cast and heat‐treated binary TeO₂ WO₃, TeO₂ CdF₂ and ternary TeO₂ CdF₂ WO₃ glasses and glass ceramics. The results were compared with those obtained by using the X‐ray diffraction technique. The effect of the WO₃ and CdF₂ contents on the TeO₂ glass network and the intensity ratios of the deconvoluted Raman peaks were determined. The shifts in the Raman band wavenumbers and the intensity values for each band were investigated. The Raman results indicated that the glasses were mainly formed by the [TeO₄] and [TeO₃] units. The [TeO₄] units convert to [TeO₃] units with the addition of WO₃ and CdF₂ into tellurite glasses. All the crystalline phases such as α‐TeO₂, δ‐TeO₂ and γ‐TeO₂ existing in the TeO₂ WO₃, TeO₂ CdF₂ and TeO₂‐ WO₃ CdF₂ glasses were determined. The transformation of the metastable γ‐TeO₂ phase into stable α‐TeO₂ was observed for the (1 − x)TeO₂ xWO₃ (where x = 0.15, 0.20, 0.25), 0.90Te₂ 0.10CdF₂, the 0.85TeO₂ 0.10CdF₂ 0.05WO₃ and 0.80TeO₂ 0.10CdF₂ 0.10WO₃ glasses, and the transformation of the metastable δ‐TeO₂ phase into the stable α‐TeO₂ was also observed for the TeO₂ CdF₂ WO₃ glass system. In addition, an unidentified phase formation, labeled ε, was determined. Copyright © 2009 John Wiley & Sons, Ltd.     

The effect of the 4MAT method (learning styles and brain hemispheres) of instruction on achievement in mathematics

The purpose of this study was to determine the efficiency of 4MAT method of instruction in which learning style and cerebral hemispheres are taken into account in teaching the binary operation and its properties in mathematics. The sample of this study comprised 58 ninth grade students in two separate classes in a high school. One of the classes was selected as the experimental group in which 4MAT method of instruction was used; and the other class was selected as the control group in which the traditional teaching was given, and this selection was performed randomly. The data have been obtained primarily from three scales, namely ‘mathematical knowledge test’, ‘mathematical attitude scale’ and ‘knowledge test on binary operation and its properties’. It has been determined that 4MAT method of instruction was more efficient than the traditional method in teaching of the binary operation subject in mathematics.     

Nonexistence results for a fractional problem arising in thermal diffusion in fractal media

We consider the Cauchy problem for the fractional differential equation

D^1+αu+D^βu=Δu+h(t,x)|u|^p