Sustainable Concrete Using Industrial By-product Waste

Alternatives to normal concrete (NC) have been investigated heavily in the last decade, Sulfur concrete is one of the promising substitutes as it works as a binder that replaces the use of cement and water to form a more sustainable option. The objective of this case study was to investigate the effect of using carbide lime waste as aggregate to produce sulfur-based concrete. To achieve this, characterization of the mix components was done after that the mechanical properties of sulfur concrete proportioned with various aggregate types were evaluated. Results revealed that the use of fillers enhanced the properties of the mix and that the mix illustrated superior mechanical properties. Moreover, the study recommended further research to prove the durability of the mix

Biodegradable Scaffolds for Gastric Tissue Regeneration

Tissue engineering has been viewed as a valid approach toward the partial or total replacement of defective tissues and organs. Recent advances in nanotechnology have made it possible to develop biocompatible materials at the micro- and nano-scales to be used as scaffolds for cellular growth and regeneration of defective tissues. Gastric mucosal lining is an example of soft tissues that are highly susceptible to damage due to various reasons including cancer or ulcer development. Current therapeutic approaches to these diseases have some limitations. This chapter describes the basis for development of a novel modality combining nanotechnology, stem cells, and tissue engineering for the replacement of defective gastric tissues using synthetic biocompatible scaffolds. These microfibrous scaffolds are seeded with gastric stem cells, which are studied for their proliferation and differentiation into functional gastric mucous cells

Experimental investigation of long-term performance of fiber-reinforced epoxy and polyurethane polymer composites

The primary challenge encountered by polymers and their composites when exposed to saline water is their inadequate ability to withstand wear and tear over time. With a potential to replace conventional materials the long-term performance of FRP composites is still a novice area. This manuscript thus, reports an experimental investigation and prediction of the durability of fiber-reinforced polymer composites exposed to seawater at different temperatures. E-glass/epoxy and E-glass/polyurethane samples were exposed to 23 °C, 45 °C and 65 °C seawater for up to 2700 days (90 months). Tensile tests evaluated the mechanical performance of the composite as a function of exposure time, and strength-based technique was used to assess the durability. The experimental results revealed that the tensile strength of E-glass/epoxy composite decreased by 6.3% and 48.9% after 90 months in seawater at 23 and 65 °C, respectively, whereas it declined by 37.6% and 63.6% respectively for E-glass/Polyurethane composite. The prolonged immersion in seawater results in plasticization and swelling in the composite material, which accelerates the fiber/matrix debonding. SEM micrographs indicate fiber/matrix debonding, potholing, fiber pull-out, river line marks, and matrix cracking which showcases deterioration in the tensile properties of both composites

Physical and gas permeation properties of five-layer polyethylene film used as greenhouse roof

The effect of sand wind ageing simulation performed under different conditions for a five-layer film consisting of polyethylene, poly-vinyl-acetate and various additives has been investigated. The mechanical properties of the five-layer films after several treatments were evaluated, together with their surface morphology - analysed by using Fourier transform infrared and contact angle - and gas permeation properties. The experimental analysis indicated that these treatments had a significant influence on the surface of the film only. An attempt has been done to compare the properties of the five-layer films with the monolayer and tri-layer films with or without air bubble under similar conditions

Principles and Characteristics of Different EDM Processes in Machining Tool and Die Steels

Electric discharge machining (EDM) is one of the most efficient manufacturing technologies used in highly accurate processing of all electrically conductive materials irrespective of their mechanical properties. It is a non-contact thermal energy process applied to a wide range of applications, such as in the aerospace, automotive, tools, molds and dies, and surgical implements, especially for the hard-to-cut materials with simple or complex shapes and geometries. Applications to molds, tools, and dies are among the large-scale initial applications of this process. Machining these items is especially difficult as they are made of hard-to-machine materials, they have very complex shapes of high accuracy, and their surface characteristics are sensitive to machining conditions. The review of this kind with an emphasis on tool and die materials is extremely useful to relevant professions, practitioners, and researchers. This review provides an overview of the studies related to EDM with regard to selection of the process, material, and operating parameters, the effect on responses, various process variants, and new techniques adopted to enhance process performance. This paper reviews research studies on the EDM of different grades of tool steel materials. This article (i) pans out the reported literature in a modular manner with a focus on experimental and theoretical studies aimed at improving process performance, including material removal rate, surface quality, and tool wear rate, among others, (ii) examines evaluation models and techniques used to determine process conditions, and (iii) discusses the developments in EDM and outlines the trends for future research. The conclusion section of the article carves out precise highlights and gaps from each section, thus making the article easy to navigate and extremely useful to the related research communit

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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Sensors Location Effect on the Dynamic Behaviour of the Composite Structure with Flaw Detection

In this paper presents an experimental and numerical investigation ofthe natural frequency of composite material cantilever plates. The stacking sequence of tbe composite plate is Quasi-isotropic laminated plate is [2(0j/±45°/2(90°)] The plate was subjected to incremental cuts and tests to determine changes in new modal properties. The study included white noise and sinusoidal dynamic testing techniques and a virtual instrument dynamic analyzer. In this study also, determining the resonant frequencies of the undamaged and damaged plate, and evaluating the capabilities of piezoelectric ceramics (PZT\u27s) for fault detection based on their sensitivity and accuracy changes in modal parameters. Numerical results are obtained using finite element software for the composite materials plates. The experimental and numerical results are very good agreement for the composite material cantilever plates with and without damage

Mixed Mode Stable Crack Extensions Through Stiffened Specimens

This study presents an experimental investigation of fracture mechanics for isotropic material, aluminum alloy D16AT. The problem of stable crack growth (SCG) has been addressed in this paper. Experimental results are presented for symmetrically stiffened and unstiffened three point bend specimens subjected to different modes, mode I and mixed mode. The stiffeners are doubly bonded to the fatigue pre-cracked specimens parallel to the length at a certain distance behind the crack tip using an adhesive Redux 410 NA. Results concerning load displacement variation, growth of plastic zones, instantaneous crack edge profiles, and tunneling are presented. There is evidence that the whole stable growth can be characterized by the crack opening angle criterion. The stiffening helps to increase both initiation and maximum fracture loads substantially

Durability of mono-layer versus tri-layers LDPE films used as greenhouse cover: Comparative study

The mono-layer low density polyethylene LDPE films are often used as a cover for the greenhouses. Recently, there are few attempts for utilizing the tri-layers LDPE films as substitute for mono-layer film. The degradation and fracture behaviour with regard to abrasion of that new generation of polymeric greenhouse covers presenting a sandwich structure made of three layers of LDPE have been studied and compared with that obtained for monolayer film often used in North Africa for plasticulture devices. Surface analysis and mechanical properties have been analysed on samples having undergone natural conditions in the north of Africa (Algeria). The results revealed that the degradation performance of these new tri-layers films is found to be quietly better than that of the mono-layer film, with regard to the mechanical and surface energy properties. The lifespan of these films under natural conditions in the north of Algeria is estimated to be 10 and 5 months for the tri-layer and mono-layer films, respectively