Unlike conventional materials removal methods, additive manufacturing (AM) is based on a novel materials incremental manufacturing philosophy. Additive manufacturing implies layer by layer shaping and consolidation of powder feedstock to arbitrary configurations, normally using a computer controlled laser. The current development focus of AM is to produce complex shaped functional metallic components, including metals, alloys and metal matrix composites (MMCs), to meet demanding requirements from aerospace, defence, automotive and biomedical industries. Laser sintering (LS), laser melting (LM) and laser metal deposition (LMD) are presently regarded as the three most versatile AM processes. Laser based AM processes generally have a complex non-equilibrium physical and chemical metallurgical nature, which is material and process dependent. The influence of material characteristics and processing conditions on metallurgical mechanisms and resultant microstructural and mechanical properties of AM proc...

Laser additive manufacturing of metallic components: materials, processes and mechanisms

Selective laser melting of iron-based powder

Surface plasmon resonance (SPR) is a label-free detection method which has emerged during the last two decades as a suitable and reliable platform in clinical analysis for biomolecular interactions. The technique makes it possible to measure interactions in real-time with high sensitivity and without the need of labels. This review article discusses a wide range of applications in optical-based sensors using either surface plasmon resonance (SPR) or surface plasmon resonance imaging (SPRI). Here we summarize the principles, provide examples, and illustrate the utility of SPR and SPRI through example applications from the biomedical, proteomics, genomics and bioengineering fields. In addition, SPR signal amplification strategies and surface functionalization are covered in the review.

/pdf/surface-plasmon-resonance-a-versatile-technique-for-4g8dmnlofz.pdf

Surface Plasmon Resonance: A Versatile Technique for Biosensor Applications

Al-12Si specimens are produced by selective laser melting (SLM) from gas atomized powders. An extremely fine cellular structure is observed with residual free Si along the cellular boundaries. Room temperature tensile tests reveal a remarkable mechanical behavior: the samples show yield and tensile strengths of about 260. MPa and 380. MPa, respectively, along with fracture strain of ~3%. The effect of annealing on microstructure and related tensile properties is examined and the results demonstrate that the mechanical behavior of the Al-12Si SLM samples can be tuned within a wide range of strength and ductility through proper annealing treatment.

Microstructure and mechanical properties of Al-12Si produced by selective laser melting: Effect of heat treatment

Progress on the morphological control of conductive network in conductive polymer composites and the use as electroactive multifunctional materials

This work attempts to offer solutions to some of the problems of processing high carbon, high-density steels. Thermocalc modelling was used to predict the amount of densifying liquid phase for a range of alloys versus sintering temperature, in the range 1285 to 1300 ○ C and 1.2 to 1.4 wt.% C. The water gas reaction forms CO gas in the early part of sintering and can lead to large porosity, which lowers mechanical properties. With the use of careful powder drying, low dew point atmospheres and optimisation of heating profiles, densities in excess of 7.4 g/cm 3 can readily be achieved. The brittle microstructure, containing carbide networks, is transformed by intelligent heat treatment to a tougher one of ferrite plus sub-micron spheroidised carbides. This gives the potential for production of components, which are both tough and suitable for sizing to improve dimensional tolerance.

/pdf/processing-and-heat-treatment-of-high-carbon-liquid-phase-16u8qkjti0.pdf

Processing and heat treatment of high carbon liquid phase sintered steels

Widefield surface plasmon resonance (WSPR) microscope provides high resolution imaging of the cell-substrate interface. We report the application of our WSPR imaging system to study the interaction of keratinocytes with the liquid crystals (LC). Imaging of the fixed cell-LC-gold and fixed cell-gold interfaces were performed in air using a 1.45 NA objective based system. In the WSPR microscopy technique, keratinocytes were found forming multiple narrow concentric rings with the presence of liquid crystals but these cells expressed wide band of contact area when they are directly cultured on the glass surface. Our work showed the feasibility of using WSPR microscopy system in imaging cells interaction with liquid crystals.

http://ieeexplore.ieee.org/iel7/6490105/6498007/06498082.pdf

Characterizing the interfacial topology of cells attached to liquid crystals

Articular cartilage is highly capable of withstanding repeated loading, considerable stress, and friction. However, unlike other types of connective tissue, it has very low capacity to repair due to the lack of nerves, blood vessels and lymphatics [1]. It was shown in previous studies [2] that treating primary chondrocyte monolayers with 1 μM of WIN55, 212-2 increased the rate of wound closure and cell proliferation and those treating primary chondrocyte monolayers with 2 μM of the same synthetic cannabinoid decreased rate of wound closure and cell proliferation. Moreover, both treatments notably reduced cell lengths, but by different percentages. These results prompted further investigation of the effect of WIN55, 212-2 (WIN-2) on chondrocyte protein expression. Understanding the mechanisms regulating cellular behaviour, e.g. proliferation, migration, morphology, phenotype and cell adhesion is crucial for tissue engineering [3]. Cells receptor membranes bind to their ligands by expressing different types of integrins depending on the extracellular matrix [4]. Furthermore, functionality of cells relies in part on the extra cellular matrix (ECM) protein surrounding the cell [5]. For instance, collagen type-II rich ECM promotes chondrocyte proliferation and differentiation [6].

The Effect of WIN55, 212-2 on Protein S100, Matrix Metalloproteinase-2 and Nitric Oxide Expression of Chondrocyte Monolayer

This study investigated the effect of pulse electric field (PEF) exposure on cervical cancer cells (HeLa cells) in an in-vitro wound repair model. The study mainly focused on the healing time of HeLa cell line wound model. During the experiments HeLa cells were maintained at 37°C in a modified Chamlide EC magnetic chamber where they were exposed to high electric fields. A Nikon inverted microscope (Ti-series) with Metamorph® time lapse software were used to monitor, image and capture photomicrographs and videos of the cells. The tests carried out during this study revealed that pulse electric field enhanced the migration of HeLa cells. Cells exposed to PEF (1kV/cm, 100μs, and single pulse) healed the wound in ~2 hours (from initial wound gap of 54.53μm ± 0.55SD to 0.66μm ± 0.61SD). On the other hand, non-PEF (control) healed the wound in ~10 hours (from initial wound gap of 56.33μm ± 0.57SD to 0.46μm ± 0.45SD). It was therefore found that the healing rate with PEF is ~five times faster than non-PEF group. It is believed that PEF usage on diseased biological cells would enable a novel method for assisting drug free wound repair systems and many other potential biomedical engineering applications such as treatment of neurological disorders including Alzheimers and Parkinsons.

Study on Pulse Electric Field Exposure Effect on HeLa Cells For Wound Healing Application

Blood clotting was reported in April 2020 [1] as another serious symptom due to COVID-19, but also came other reports such as young adults dying due to strokes and heart attacks [2]. The currently known head-to-toe symptoms of COVID-19, seem to indicate vascular as well as respiratory diseases and that 40% of related death are due to cardiovascular complications [2]. In a recently published journal paper in Lancet [3], the authors found that SARS-CoV-2 virus can infect the endothelial cells that line the inside of blood vessels noting that endothelial cells protect the cardiovascular system and release proteins that influence everything from blood clotting to the immune response. In the same paper, the authors showed damage to endothelial cells in the lungs, heart, kidneys, liver, and intestines in patients with Covid-19. Therefore, the emerging belief is that the novel coronavirus is a respiratory illness to begin with, but as it spreads further into blood vessels it becomes a vascular illness that is capable of killing patients via vascular system.

Mansour Youseffi

Papers

Processing and heat treatment of high carbon liquid phase sintered steels

Characterizing the interfacial topology of cells attached to liquid crystals

The Effect of WIN55, 212-2 on Protein S100, Matrix Metalloproteinase-2 and Nitric Oxide Expression of Chondrocyte Monolayer

Study on Pulse Electric Field Exposure Effect on HeLa Cells For Wound Healing Application

The Novel Coronavirus Causes Impairment of Blood Vessels and Respiratory System with Head-to-Toe Symptoms and Vaccine Development: An Overview