The purpose of this study is to develop a fast setting and suitable degrading Mg-calcium silicate cement (Mg-CS) and a mechanism using Mg ions to stimulate human periodontal ligament cells (hPDLCs).Mechanical strength and stability have been determined by testing the diametral tensile strength; the degradation of cements has been measured by ascertaining the number of ions released in simulated body fluid. Other cell characteristics such as proliferation, differentiation and mineralization, and hPDLCs when cultured on cement surfaces were also examined. The results show that the degradation rate of Mg-CS cements depends on the Mg content in CS. Regarding in vitro bioactivity, the CS cements were covered with clusters of apatite spherulites after immersion for 30 days, while there was less formation of apatite spherulites on the Mg-rich cement surfaces. In addition, researchers also explored the effects of Mg ions on the cementogenesis and angiogenesis differentiation of hPDLCs in comparison with pure CS cement. The proliferation, alkaline phosphatase, cementogenesis-related proteins (CEMP1 and CAP), and angiogenesis-related protein (vWF and ang-1) secretion of hPDLCs were significantly stimulated when the Mg ion concentration of the medium was increased. The research results also suggest that Mg-CS cements with this modified composition stimulate hPDLC behaviour and so may be good biomaterials for bone substitutes and hard tissue regeneration applications as they stimulate cementogenesis/angiogenesis.

We provide an overview of cloud computing: evolution, benefits, and challenges. Then we examine the risk characteristics identified in accounting and auditing literature by comparing a hand-collected sample of cloud computing companies with a matched sample of non-cloud computing companies. The study uses a comprehensive set of factors used in accounting and auditing literature to describe client business risk, audit risk, and auditor-related risk. Unsurprisingly, the findings show that large companies in the historically high-risk information technology industries provide cloud computing. More interestingly, the results show that cloud computing is more leveraged, and more likely to have a material weakness and longer audit tenure. Cloud computing companies are also more likely to restate their financial statement after providing cloud technologies. Some of the risk variables we used in the study are not statistically significant in capturing the risks of cloud providers (e.g., security, privacy, availability, confidentiality). The study contributes to the literature in IT outsourcing in general, and in cloud computing more specifically. The study also responds to the recent call for insightful research in cloud computing.

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