For each integer n 2, let β (n) be the sum of the distinct prime divisors of n and let B(x) stand for the set of composite integers n x such that n is a multiple of β (n). Upper and lower bounds are obtained for the cardinality of B(x). §

The superconvergence of composite trapezoidal rule for Hadamard finitepart integral on a circle and its application Xiaoping Zhang a; Jiming Wu b; Dehao Yu a a LSEC, Institute of Computational Mathematics and Scientific/Engineering Computing, Academy of Mathematics and Systems Science, CAS, Beijing, P.R. China b Laboratory of Computational Physics, Institute of Applied Physics and Computational...

For solving the linear system A x = b we introduce some iteration algorithms, where A = (aij) and b = bi a given matrix and a column vector with elements from a Brouwerian lattice, and is a max–min composite operation. 2005 Elsevier Inc. All rights reserved.

The purpose of the current study was to evaluate the influence of light sources on the mechanical properties and wear characteristics of indirect composite materials. The two composite materials used were Estenia C&B and Epricord. The three laboratory polymerization units used, of which the wavelength range was 400-500 nm, were Hyper LII (two metal halide lamps of 4.82 mW/cm(2)), α-Light II (on...

OBJECTIVES This study aimed to assess the effects of two energy drinks on color change (ΔE) of two methacrylate-based and a silorane-based composite resin after one week and one month. MATERIALS AND METHODS Thirty cubic samples were fabricated from Filtek P90, Filtek Z250 and Filtek Z350XT composite resins. All the specimens were stored in distilled water at 37°C for 24 hours. Baseline color ...

Physical properties such as surface hardness of dental materials are directly linked to their clinical behavior. The aim of this study was to investigate the influence of extended curing time on the polymerization depth offluoride-containing materials used as pit and fissure sealants. Conventional and extended exposure times (20 and 60 seconds) were used to photoactivate a gold-standard pit and...

Introduction: The aim of the present study was to evaluate the effect of glass ceramic insert in the sandwich technique to reduce microleakage in class II composite resin restorations. Methods: Sixty sound human upper second premolars were selected and randomly divided into six groups (n=10). Class II boxonly cavities were prepared in distal aspects of each tooth with gingival margin located ap...

The objective of the study was to assess the effect of the cavity design factor (C-factor) on polymerization stress development (PSD) in resin composites. An experimental resin (BT resin) was prepared, which contained 2,2-bis[p-(2'hydroxy-3'-methacryloxypropoxy)phenylene]propane (B) and triethylene glycol dimethacrylate (T) in 1:1 mass ratio, and an activator for visible light polymerization. A...

STATEMENT OF PROBLEM Severe tooth wear localized to the anterior maxillary or mandibular teeth with loss of interocclusal space is difficult to manage. PURPOSE This study evaluated the outcome of composite restorations placed at an increased vertical dimension of occlusion in such patients. METHODS AND MATERIAL Sixteen patients were restored with 104 restorations in 2 groups. In group A, Du...

Submitted for the MAR08 Meeting of The American Physical Society Spectral representation theory of graded composite materials K.L. CHAN, C.M. KWOK, K.W. YU, The Chinese University of Hong Kong — In graded composite materials, the physical properties can vary continuously in space and it may give different physical phenomena when compared with homogeneous materials. The Bergman-Milton spectral r...