Microstructure and mechanical characterization of in situ synthesized AA6061/(TiB2+Al2O3) hybrid aluminum matrix composites

Abstract: TiB2 and Al2O3 particulates reinforced AA6061 aluminum matrix composites (AMCs) were synthesized by in-situ reaction of titanium (Ti) and boric acid (H3BO3) powders with molten aluminum. AMCs were fabricated using an electric stir casting furnace under a controlled environment. Heat flow curves of differential thermal analysis (DTA) showed that the synthesis temperature for the formation of TiB2 and Al2O3 using Al-Ti-H3BO3 reaction system was 950°C. The in-situ synthesized composites were characterized using XRD, FESEM, TEM and EBSD. XRD results revealed the formation of TiB2 and Al2O3 particulates in the composite. FESEM micrographs revealed a homogenous distribution of both the particulates with good interfacial bonding. EBSD maps showed that the in-situ formed TiB2 and Al2O3 particulates refined the grains of the aluminum matrix from 103 μm at 0 wt.% to 14 μm at 15 wt.%. Al2O3 particles exhibited spherical shape while TiB2 particles displayed hexagonal and cubic shapes. The formation of ultrafine and nano scale thermodynamically stable TiB2 and Al2O3 particles enhanced the microhardness and the tensile strength of the 2 AMCs. The microhardness and the tensile strength were respectively 122 HV and 287 MPa at 15 wt.%

Natural flavonoids as potential multifunctional agents in prevention of diabetic cataract

Cataract is one of the earliest secondary complications of diabetes mellitus. The lens is a closed system with limited capability to repair or regenerate itself. Current evidence supports the view that cataractogenesis is a multifactorial process. Mechanisms related to glucose toxicity, namely oxidative stress, processes of non-enzymatic glycation and enhanced polyol pathway significantly contribute to the development of eye lens opacity under conditions of diabetes. There is an urgent need for inexpensive, non-surgical approaches to the treatment of cataract. Recently, considerable attention has been devoted to the search for phytochemical therapeutics. Several pharmacological actions of natural flavonoids may operate in the prevention of cataract since flavonoids are capable of affecting multiple mechanisms or etiological factors responsible for the development of diabetic cataract. In the present paper, natural flavonoids are reviewed as potential agents that could reduce the risk of cataract formation via affecting multiple pathways pertinent to eye lens opacification. In addition, the bioavailability of flavonoids for the lens is considered

Nanopore sequencing for rapid diagnostics of salmonid RNA viruses

This work received support from the Biotechnology and Biological Sciences Research Council (grant BB/M010996/1) and Marine Scotland Science. The authors thank Dr Elena Fringuelli (Agri-Food and Biosciences Institute, Belfast) for providing some of the SAV material used.Peer reviewedPublisher PD

Simple Rule To Predict Boundedness of Multiexciton States in Covalently Linked Singlet-Fission Dimers

Because of the potential for increasing solar cell efficiencies, significant effort has been spent understanding the mechanism of singlet fission. We provide a simple connectivity rule to predict whether the through-bond coupling will be stabilizing or destabilizing for the ¹(<i>TT</i>) state in covalently linked singlet-fission chromophores. By drawing an analogy between the chemical system and a simple spin–lattice, one is able to determine the ordering of the multiexciton spin state via a generalized usage of Ovchinnikov’s rule. This allows one to predict (without any computation) whether the ¹(<i>TT</i>) multiexciton state will be bound or unbound with respect to the separated triplets in covalently linked singlet-fission dimers. To test our hypothesis, we have performed ab initio calculations on a systematic series of covalently linked singlet-fission dimers. Numerical examples are given, and the limitations of the proposed theory are explored

Synthesis and microstructure characterization of in situ formed of Al2O3-TiB2 AMCs particles on AA6061 aluminium matrix composites

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Continuous Droplet-Actuating Platforms via an Electric Field Gradient: Electrowetting and Liquid Dielectrophoresis

This work develops a technology for actuating droplets of any size without the requirement for high voltages or active control systems, which are typically found in competitive systems. The droplet actuation relies on two microelectrodes separated by a variable gap distance to generate an electrostatic gradient. The physical mechanism for the droplet motion is a combination of liquid dielectrophoresis and electrowetting. Investigating the system behavior as a function of the driving frequency identified the relative contribution of these two mechanisms and the optimum operating conditions. A fixed signal frequency of 0.5 kHz actuated various liquids and contaminants. Droplet actuation was demonstrated on several platforms, including linear, radial-symmetric, and bilateral-symmetric droplet motion. The electrode designs are scalable and can be fabricated on a flexible and optically transparent substrate: these key advancements will enable consumer applications that were previously inaccessible. A self-cleaning platform was also tested under laboratory conditions and on the road. This technology has significant potential in microfluidics and self-cleaning platforms, for example, in the automotive sector to clean body parts, camera covers, and sensors