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.

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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 study aimed at characterizing the responses and cell traction forces of keratinocytes after treated with trypsin and cytochalasin-B using a liquid crystal based cell traction force transducer. The physical restructuring of the cell and the deformation lines induced in the liquid crystal surface were profiled using phase contrast microscopy. The liquid crystal based cell traction force transducer allowed experiments involving the dissolution of the cytoskeleton via cytochalasin-B and trypsinization to identify clear differences in cell responses to the two treatments indicated that the attachment of the cells was mediated by integrins and enforced by actin filaments. This work indicates that the new liquid crystal based sensor can be used to interrogate the kinetic and cytoskeletal responses of cells to the infusion of compounds known to interact with the actin cytoskeleton and adhesion proteins.

Effects of trypsin and cytochalasin-B treatments to cell traction forces

Effect of transforming growth factor-β on up/down regulation of integrin-β1 in primary chondrocyte culture

Growing three dimensional (3D) cells is an emerging research in tissue engineering. Biophysical properties of the 3D cells regulate the cells growth, drug diffusion dynamics and gene expressions. Scaffold based or scaffoldless techniques for 3D cell cultures are rarely being compared in terms of the physical features of the microtissues produced. The biophysical properties of the microtissues cultured using scaffold based microencapsulation by flicking and scaffoldless liquid crystal (LC) based techniques were characterized. Flicking technique produced high yield and highly reproducible microtissues of keratinocyte cell lines in alginate microcapsules at approximately 350 ± 12 pieces per culture. However, microtissues grown on the LC substrates yielded at lower quantity of 58 ± 21 pieces per culture. The sizes of the microtissues produced using alginate microcapsules and LC substrates were 250 ± 25 μm and 141 ± 70 μm, respectively. In both techniques, cells remodeled into microtissues via different growth phases and showed good integrity of cells in field-emission scanning microscopy (FE-SEM). Microencapsulation packed the cells in alginate scaffolds of polysaccharides with limited spaces for motility. Whereas, LC substrates allowed the cells to migrate and self-stacking into multilayered structures as revealed by the nuclei stainings. The cells cultured using both techniques were found viable based on the live and dead cell stainings. Stained histological sections showed that both techniques produced cell models that closely replicate the intrinsic physiological conditions. Alginate microcapsulation and LC based techniques produced microtissues containing similar bio-macromolecules but they did not alter the main absorption bands of microtissues as revealed by the Fourier transform infrared spectroscopy. Cell growth, structural organization, morphology and surface structures for 3D microtissues cultured using both techniques appeared to be different and might be suitable for different applications.

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Comparison of biophysical properties characterized for microtissues cultured using microencapsulation and liquid crystal based 3D cell culture techniques

A valve (20) for the sealing cuff (10) of a tracheal tube has a valve member (40) urged against a valve seal (36, 37) by an MRI-safe resilient member (42) of neoprene or nitrile. The valve includes a two-part actuator (70) by which the valve member is displaced. Before use, during storage, the valve member is in a closed position with the resilient member relatively relaxed. When the valve is opened for the first time by inserting a syringe or the like, the two-part actuator arrangement is moved forwards to unseat the valve member to allow flow. This causes inclined surfaces (88) and (92) on the two parts (72) and (73) of the actuator to rotate the forward part slightly. When the syringe is removed to allow the valve to close, the forward part of the actuator latches on a surface (34) of the housing (21) in an operational position where the valve is closed.

Valves and tubes including valves

Widefield Surface Plasmon Resonance (WSPR) microscope was used to investigate cell surface interactions under two different culture conditions: bone cells cultured on SPR substrate with transforming growth factor β3 (TGF-β3) and without as control. Trypsinisation was carried out in order to investigate its effect on cell detachment, in the presence of TGF-β3, HCl or BSA/HCl solutions. Trypsin was therefore added to four groups of bone cells with addition of TGF-β3, HCl, HCl/BSA solutions and one additional flask as control. These results further confirmed that application of TGF-β3, HCl and HCl/BSA decreased the degree of cell attachment on surface of culture flasks. HCl and BSA/HCl were tested as they are the carriers and solvents for TGF-β3. Cell detachment in control was about 43% after 6 min, which is slow. Bone cells in the presence of BSA/HCl started detaching from the surface about 4–5 min and cell detachment was about 63% after 6 min which was faster as compared to the control. Bone cells in the presence of HCl alone started detaching from the surface about 2 min (after applying trypsin) and cell detachment was about 69% after 6 min which was faster compared to the BSA/HCl and control. Trypsinisation experiments for bone cells cultured with TGF-β3 (50 ng/ml) showed that cells started to detach from the surface about 1 min after application of trypsin and cell detachment was about 85% after 4 min which was faster as compared to the control, HCl and BSA/HCl.

Biological Application of Widefield Surface Plasmon Resonance Microscope to Study Cell/Surface Interactions and the Effect of TGF-β3, HCL and BSA/HCL on Cell Detachment Assay of Bone Cells Monolayer

Mansour Youseffi

Papers

Effects of trypsin and cytochalasin-B treatments to cell traction forces

Effect of transforming growth factor-β on up/down regulation of integrin-β1 in primary chondrocyte culture

Comparison of biophysical properties characterized for microtissues cultured using microencapsulation and liquid crystal based 3D cell culture techniques

Valves and tubes including valves

Biological Application of Widefield Surface Plasmon Resonance Microscope to Study Cell/Surface Interactions and the Effect of TGF-β3, HCL and BSA/HCL on Cell Detachment Assay of Bone Cells Monolayer