Internal–external circumferential crack behaviour in the cement layer of total hip replacement

This study aimed to investigate crack behaviour at the internal and external surfaces of the cement layer in total hip replacement. A three‐dimensional model of the femur with the cemented prosthesis was developed and analysed. Cracks were placed on the internal, external and both internal and external surfaces of the cement layer. Stress intensity factors were measured during gait. Results revealed that the stress intensity factors modes I and III were the most dominant in the crack propagation in the cement layer. The domain of mode I was the medial and lateral sides of the cement layer. Meanwhile, the domain of mode III was the anterior and posterior sides of the cement layer. The stress intensity factor and distance from the distal end indicated an inverse relationship. The internal and external cracks had no significant interaction. Moreover, stress intensity factors at the external surface of the cement layer were higher than those on the internal surface.     

Behavior of Millstone Masonry Vaults Strengthened by Composite Materials

Sewerage systems first appeared in Paris in the middle of 19th century. Even if the majority of structures are still in working order, their general state will deteriorate inexorably, and as reconstruction is not always possible for cost and social impact reasons, rehabilitation is a solution adopted by many clients. It is necessary to resort to new rehabilitation techniques. Reinforcement by bonding composite materials has many advantages compared to other techniques. The objective of the experimental campaign presented in this paper is to study the addition of a lining by means of mortar reinforced by thin composite materials so as to restore masonry structures. To that purpose, crushing tests on masonry vaults have been carried out. The application of a lining made of mortar reinforced with composite materials has allowed increasing the breaking load and delaying the occurrence of the first cracks. This article presents the characterization of the materials. Moreover, the results of the breaking tests applied to masonry vaults are shown in this paper. A comparison with a traditional type of rehabilitation by a 6 cm-thick shotcrete lining will be performed.     

Effect of elevated temperatures on mechanical properties of high‐strength concrete containing varying proportions of hematite

Aggregates typically constitute 70 to 80 wt% of concrete, and therefore their type, size, and structure play an essential role in modifying the properties of concrete. When concrete is used for shielding nuclear applications, temperature is also a key factor. This study investigates the effects of elevated temperatures (25 °C, 200 °C, 400 °C, 600 °C, and 800 °C), heating durations (1, 2, and 3 h), and cooling regimes (air, and water cooling) on mechanical properties of concrete containing different proportions of hematite. A sample of plain concrete was produced for comparison purposes by using river sand, crushed sand, and crushed aggregates. Replacement ratios of 15%, 30%, 45%, and 60% were used for hematite aggregates. The cement content and water–cement ratio were 450 kg/m³ and 0.38, respectively. Slump values of fresh concretes as well as unit weight, compressive strength, flexural strength, splitting tensile strength, and elasticity modulus values of hardened concrete were determined. The addition of hematite into concrete seems to improve its mechanical properties, and hematite concretes have better thermal stability at elevated temperatures than plain concrete does. Copyright © 2011 John Wiley & Sons, Ltd.     

Volatile and nonvolatile chemical composition of some date fruits (Phoenix dactylifera L.) harvested at different stages of maturity

Physico‐chemical and aroma volatile compositions of three date palm cultivars were studied throughout fruit maturation (besser, rutab and tamr stages) during 2008 harvest season. The studied parameters varied significantly through the different stages, with some variations also depending on the cultivar. Length and width of the three types of dates showed a progressive decrease during ripening. The pH level, total sugars and ash contents significantly increased up to tamr stage. Conversely, moisture, lipid and protein contents decreased. The profile of the volatile aroma compounds was evaluated using solid‐phase micro‐extraction. Sixty‐nine compounds were detected during maturation, accounting from 98.5% to 99.6% at besser, 93.1% to 99.2% at rutab and 94.3% to 98.4% at tamr stages of the total identified volatiles. The present study sheds more light on chemical characteristics of the studied cultivars that can be used in many industrial processes.