Showing papers by "Daryoosh Vashaee published in 2018"

Multiplexed microarrays based on optically encoded microbeads

Abstract: In recent years, there has been growing interest in optically-encoded or tagged functionalized microbeads as a solid support platform to capture proteins or nucleotides which may serve as biomarkers of various diseases. Multiplexing technologies (suspension array or planar array) based on optically encoded microspheres have made possible the observation of relatively minor changes in biomarkers related to specific diseases. The ability to identify these changes at an early stage may allow the diagnosis of serious diseases (e.g. cancer) at a time-point when curative treatment may still be possible. As the overall accuracy of current diagnostic methods for some diseases is often disappointing, multiplexed assays based on optically encoded microbeads could play an important role to detect biomarkers of diseases in a non-invasive and accurate manner. However, detection systems based on functionalized encoded microbeads are still an emerging technology, and more research needs to be done in the future. This review paper is a preliminary attempt to summarize the state-of-the-art concerning diagnostic microbeads; including microsphere composition, synthesis, encoding technology, detection systems, and applications.

Field induced decrystallization of silicon: Evidence of a microwave non-thermal effect

Abstract: It is rather strange and not fully understood that some materials decrystallize when exposed to microwave radiation, and it is still debatable if such a transformation is a thermal or non-thermal effect. We hereby report experimental evidences that weight the latter effect. First, a single crystal silicon wafer exposed to microwaves showed strong decrystallization at high temperature. Second, when some areas of the wafer were masked with metal coating, only the exposed areas underwent decrystallization. Transmission electron microscopy analysis, x-ray diffraction data, and thermal conductivity measurements all indicated strong decrystallization, which occurred in the bulk of the material and was not a surface effect. These observations favor the existence of a non-thermal microwave effect.It is rather strange and not fully understood that some materials decrystallize when exposed to microwave radiation, and it is still debatable if such a transformation is a thermal or non-thermal effect. We hereby report experimental evidences that weight the latter effect. First, a single crystal silicon wafer exposed to microwaves showed strong decrystallization at high temperature. Second, when some areas of the wafer were masked with metal coating, only the exposed areas underwent decrystallization. Transmission electron microscopy analysis, x-ray diffraction data, and thermal conductivity measurements all indicated strong decrystallization, which occurred in the bulk of the material and was not a surface effect. These observations favor the existence of a non-thermal microwave effect.

Improvement of in vitro behavior of an Mg alloy using a nanostructured composite bioceramic coating

Abstract: Magnesium (Mg) alloys as a new group of biodegradable metal implants are being extensively investigated as a promising selection for biomaterials applications due to their apt mechanical and biological performance. However, as a foremost drawback of Mg alloys, the high degradation in body fluid prevents its clinical applications. In this work, a bioceramic composite coating is developed composed of diopside, bredigite, and fluoridated hydroxyapatite on the AZ91 Mg alloy in order to moderate the degradation rate, while improving its bioactivity, cell compatibility, and mechanical integrity. Microstructural studies were performed using a transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD) analysis, and energy dispersive spectroscopy (EDS). The degradation properties of samples were carried out under two steps, including electrochemical corrosion test and immersion test in simulated body fluid (SBF). Additionally, compression test was performed to evaluate the mechanical integrity of the specimens. L-929 fibroblast cells were cultured on the samples to determine the cell compatibility of the samples, including the cell viability and attachment. The degradation results suggest that the composite coating decreases the degradation and improves the bioactivity of AZ91 Mg alloy substrate. No considerable deterioration in the compression strength was observed for the coated samples compared to the uncoated sample after 4 weeks immersion. Cytotoxicity test indicated that the coatings improve the cell compatibility of AZ91 alloy for L-929 cells.

Cartilage and facial muscle tissue engineering and regeneration: a mini review

Abstract: Cartilage and facial muscle tissue provide basic yet vital functions for homeostasis throughout the body, making human survival and function highly dependent upon these somatic components. When cartilage and facial muscle tissues are harmed or completely destroyed due to disease, trauma, or any other degenerative process, homeostasis and basic body functions consequently become negatively affected. Although most cartilage and cells can regenerate themselves after any form of the aforementioned degenerative disease or trauma, the highly specific characteristics of facial muscles and the specific structures of the cells and tissues required for the proper function cannot be exactly replicated by the body itself. Thus, some form of cartilage and bone tissue engineering is necessary for proper regeneration and function. The use of progenitor cells for this purpose would be very beneficial due to their highly adaptable capabilities, as well as their ability to utilize a high diffusion rate, making them ideal for the specific nature and functions of cartilage and facial muscle tissue. Going along with this, once the progenitor cells are obtained, applying them to a scaffold within the oral cavity in the affected location allows them to adapt to the environment and create cartilage or facial muscle tissue that is specific to the form and function of the area. The principal function of the cartilage and tissue is vascularization, which requires a specific form that allows them to aid the proper flow of bodily functions related to the oral cavity such as oxygen flow and removal of waste. Facial muscle is also very thin, making its reproduction much more possible. Taking all these into consideration, this review aims to highlight and expand upon the primary benefits of the cartilage and facial muscle tissue engineering and regeneration, focusing on how these processes are performed outside of and within the body.

Thin film thermoelectric devices

Abstract: Various examples of thin film thermoelectric (TE) devices, their fabrication and applications are presented. In one example, a thin film TE device includes a first substrate including a void; a p-type TE element attached to the first substrate at a first end and extending over the void to a second end; an n-type TE element attached to the first substrate at a first end and extending over the void to a second end adjacent to the second end of the p-type TE element; and an interconnection coupling the second ends of the p-type TE element and the n-type TE element. In some examples, TE device layers can be vacuum sealed between a supporting substrate and a transparent substrate. A thermal spreader can include TE modules having a distribution of TE elements that operate in generating or cooling modes to cool IC or device hotspots using self-generated power.