STATEMENT OF PROBLEM As a physical property, wear resistance of the materials used in the fabrication of orthodontic retainers play a significant role in the stability and long term use of the appliances. OBJECTIVES To evaluate the wear resistance of two commonly used materials for orthodontic retainers: Acropars OP, i.e. a polymethyl methacrylate based material, and 3A-GS060, i.e. a polyethy...

The aim of this paper is to focus on the effect of cryogenic treatment on the microstructure, mechanical and wear properties of Al 6061 and Al 8011.  The first objective was to understand the degree to which hardness of these aluminium grades have been enhanced by giving  cryogenic on the specimens. The second objective is to check the wear resistance property of these two aluminium specimens i...

In this research, surface composite layers containing nano sized TiB2, Al2O3-TiB2, ZrO2 and CNT particles have been fabricated on Aluminum alloy substrates by friction stir processing. The effects of different processing variables such as number of passes and strengthening particle distribution, hardness, and wear properties of surface nano...

In the present study, CrN, TiN and (Ti, Cr)N coatings were deposited on D6 tool steel substrates. Physical and mechanical properties of coatings such as microstructure, thickness, phase composition, and hardness were evaluated. Phase compositions were studies by X-ray diffraction method. Mechanical properties were determined by nano-indentation technique. The friction and wear behaviour of the ...

Polyethylene wear is a great concern in total joint replacement. It is now considered a major limiting factor to the long life of such prostheses. Cross-linking has been introduced to reduce the wear of ultra-high-molecular-weight polyethylene (UHMWPE). Computational models have been used extensively for wear prediction and optimization of artificial knee designs. However, in order to be indepe...

BACKGROUND TKA with retention of the anterior cruciate ligament (ACL) may improve kinematics and function. However, conflicting reports exist concerning the prevalence of intact ACLs at the time of TKA. QUESTIONS/PURPOSES Therefore, we asked: (1) what was the ACL status at TKA; (2) what was the sensitivity and specificity of the Lachman test; (3) did MRI ACL integrity correlate with intraoper...

Tribology in the railway system is of increasing interest in the new railway era due to the demand for higher speed and load capacity. Since railway vehicles operate in an open environment, their performance depends greatly on temperature, humidity and natural and artificial contaminants. Meanwhile, the “feedback” of railway vehicles to the surroundings, such as noise and airborne particles, is...

Flying is an ecologically important behaviour in many insects, but it often results in permanent wing damage. Although wing wear in insects is often used as a method to determine insect age, and is associated with an increased risk of mortality, the causes of wing wear are unresolved. In this paper, we examine whether wing use while foraging explains wing wear in bumble bees (Bombus spp.). Wing...

BACKGROUND Most contemporary total disc replacements (TDRs) use conventional orthopaedic bearing couples such as ultrahigh-molecular-weight polyethylene (polyethylene) and cobalt-chromium (CoCr). Cervical total disc replacements incorporating polyetheretherketone (PEEK) bearings (specifically PEEK-on-PEEK bearings) have been previously investigated, but little is known about PEEK-on-ceramic bea...