This study explored the mechanisms by which crevices act as refugia for small algae during abrasive disturbances. Four substrates with different crevice features were subjected to three levels of abrasion in a stream-based experiment. Substrates were sand-grain caddisfly cases and three glass rod substrates that mimicked caddisfly cases in size and shape, as well as forming a gradient of larger...

We introduce new classes of valid inequalities, called wheel inequalities, for the stable set polytope P G of a graph G. Each \wheel connguration" gives rise to two such inequalities. The simplest wheel connguration is an \odd" subdivision W of a wheel, and for these we give necessary and suucient conditions for the wheel inequality to be facet-inducing for P W. Generalizations arise by allowin...

In this paper, an Ultrasonic testing method for inservice wheel by use of phased array technology is introduced. To meet the ultrasonic test criterion of inservice CRH wheel, groups of phased array probes and conventional probes are combined used. By study echo wave in wheel rim and wheel disk form different probes, defect analyzing methods in wheel rim and wheel disk are studied. Tests on CRH ...

This paper describes the results of room temperature joining of TiO2 / SiO2 IRF by sputter deposition with a special emphasis of improvement of adherence at the interface. This multilayer system is designed to shield the infrared energy of solar spectrum by interference reflection. The abrasion resistance of the multilayer stacks was also estimated by the Haze value after the Taber abrasion tes...

This paper describes an in-depth evaluation of an abrasion testing procedure for concrete pavers developed in Australia The test involves abrasion of the paver surface by a rapidly rotating ball race under load. Water is used both to lubricate the race and to remove debris. The investigation included the study of factors affecting the test results such as the load applied to the ball-race, the ...

The purpose of this study was to evaluate the influence of air-abrasion and subsequent heat treatment on the shear bond strength of the bond between indirect composites and a zirconia material. Four surface preparations were employed; ground flat, then heated to regenerate the crystal phase (C); air-abraded with alumina for 10 s (S10), for 20 s (S20), and air-abraded for 10 s and heated (H). Di...

BACKGROUND Pulp stone, though of an unclear aetiology, is clinically common. It potentially poses procedural difficulty to the endodontist and may also be a marker of an underlying systemic condition. OBJECTIVES The study investigated pulp stone occurrence in adult restorative patients. It also highlighted the relationship between pulp stone and pristine posterior teeth, chronic periodontitis...

AIM The aim of this in vitro study was to evaluate the shear bond strength of a one-step self-etch adhesive to dentin pretreated with phosphoric acid, air abrasion, or laser. METHODS AND MATERIALS Fifty-six extracted non-carious human mandibular molars were mounted and the occlusal surfaces ground with a mechanical grinder to obtain flat occlusal dentin surfaces. The teeth were randomly divid...

Factors that affect water loss rates (WLRs) are poorly known for organisms in natural habitats. Seed-harvester ant queens provide an ideal system for examining such factors because WLRs for mated queens excavated from their incipient nests are twofold to threefold higher than those of alate queens. Indirect data suggest that this increase results from soil particles abrading the cuticle during ...

Wind resuspension (or entrainment) provides a source of dust and contaminants for the atmosphere. Conventional wind erosion models parameterize dust resuspension flux with a threshold velocity or with a horizontal abrasion flux; in the absence of abrasion the models assume dust flux is transient only. Our experiments with an uncrusted, fine material at relative humidities exceeding 40% show a l...