فهرست مطالب alireza sardarian

Current research suggests that carbon nanotubes (CNTs) as biomaterials have immense potential for applications in regenerative medicine. The focus of regenerative medicine is on developing methods that can be applied to create functional tissues, to repair or replace tissues/organs lost due to trauma or diseases. In this respect, the structural and mechanical properties of CNTs make them applicable for use as composites for tissue engineering. CNTs can act as delivery vehicles for drugs and gene therapy and thus are suitable for therapeutics in regenerative medicine. The external carbon sheath of the CNTs can be functionalized for usein targeting, drug delivery, and as imaging agents. Further intrinsic physical properties of carbon nanotubes can be harnessed for therapeutics and imaging applications. The use of carbon nanotubes has been proved as contrasting agent in imaging. This work focuses on the latest developments in applications of carbon nanotubes for regenerative medicine. Carbon nonotubes have been under investigation in the past decade for an array of applications due to their unique and versatile properties. In the field of regenerative medicine, they have shown great promise to improve the properties of tissue engineering scaffolds and perform drug delivery and imaging of engineering tissues. The work is a review of the latest advances.

Statement of the Problem: Stainless steel brackets release metallic ions following the process of corrosion in the oral environment. These released ions have potential adverse effects on health, friction between wire and bracket, staining, strength of brackets. Choosing a bracket with favorable corrosive properties; therefore, should be a goal of every practitioner.
The goal of this study is to compare the amount of corrosion among five different brands of brackets using inductively coupled plasma (ICP) mass spectrometry.
Five different brands of brackets (Dentaurum, 3M, Ortho Organizer, Cobas and O.R.G) were chosen and ten brackets were selected from each brand. A piece of stainless steel wire was ligated to each bracket. The bracket-archwire complex was then immersed in artificial saliva. Subsequently, the samples were analyzed using an ICP device and the levels of iron, chromium, nickel, and manganese ions were measured.
The findings of this study demonstrated that iron was released the most from the tested brackets, followed by nickel. We also found that the Cobas bracket had the most ion release among the tested brackets (p 0.05).
Based on the results, Ortho Organizer and ORG brackets are suggested in terms of resistance to corrosion.

As the number of applications of carbon nanotubes (CNT) in the field of nanomedicine is growing quickly (imaging, drug delivery, scaffolds for tissue engineering), questions are raised about their potential toxicity. Because their annual production is now reaching hundreds of tons per year, their application in composite materials are becoming a reality. Dissemination in the environment could also happen during different steps of their life cycle, from their production to their processing, use and finally during disposal or recycling. We will review in this paper the state of the art in the field of toxicity and ecotoxicity of carbon nanotubes and try to highlight some recommendations.

A simple, highly efficient and green procedure for the condensation of o-phenylenediamines with 1, 2-dicarbonyl compounds in the presence of vitamin C, as an inexpensive organocatalyst, is described. Using this method, variety of quinoxaline derivatives with different electron releasing and electron withdrawing substituents, are produced in high to excellent yields at room temperature in ethanol. The remarkable features of this new protocol are high to excellent conversions, relatively short reaction times, and clean reaction profiles, simple and easy experimental and work-up procedures. Thus we have been able to report another ability of vitamin C in organic chemistry synthesis which has less disastrous effect in the atmosphere and human survival.