Virtual Private Networks

Abstract

The tremendous growth and decreasing costs of Internet technology forced many companies to substitute expensive leased lines by connections based on Internet Protocols. This allows enterprises to establish Intranets and to offer remote employees to securely access such an Intranet. In addition, networks of different business partner can be interconnected forming Extranets. A key technology is the IP Security (IPSec) protocol suite that enhances the Internet Protocol (IP). IPSec introduces security comparable to leased lines but is much less costly due to the fact that Internet resources can be shared among different users. Such networks that are constructed using secure methods to transfer information are called Virtual Private Networks. They represent a further step towards a more secure, less costly and universal communications platform.

Dry Sliding Wear Characteristics of Ti-Nb-Si Alloys for Biomedical Application

“…For example, Ti-6Al-4V ELI(Extra Low Interstitials) has been widely used to date in the field of orthopedic implantation due to their reasonable biocompatibility, excellent polarization resistance and mechanical property compared to the other biomedical metallic materials. Steinemann et al have been studied the cytotoxicity of pure metals based on the relationship between biocompatibility and polarization resistance i.e., corrosion resistance [1]. Up to date V, Al and Fe have been known as higher cytotoxic elements.…”

Mechanical Property and Elastic Modulus of Metastable Ti-Nb Based Alloys with Si Addition

“…This activity for development of new Ti based alloy would be correlated with the requirement of non-toxic elements and low elastic modulus. As far as biomedical application is concerned, the surface modification would be desirable for the suppression of dissolution of toxic elements such as V and Al through the formation of stable oxide layer [1]. However, this is not guaranteed to be mechanically and chemically stable in human body for long time exposure.…”