Active coke Carbonaceous materials as catalysts for alkane dehydrogenation

The catalytic dehydrogenation (DH) and oxidative dehydrogenation (ODH) of light alkanes are of significant industrial importance. In this work both carbonaceous materials deposited on VOx/Al2O3 catalysts during reaction and unsupported carbon nanofibres (CNFs) are shown to be active for the dehydrogenation of butane in the absence of gas-phase oxygen. Their activity in these reactions is shown to be dependent upon their structure, with different reaction temperatures yielding structurally different coke deposits. Terahertz time-domain spectroscopy (THz-TDS), among other techniques, has been applied to the characterisation of these deposits – the first time this technique has been employed in coke studies. TEM and other techniques show that coke encapsulates the catalyst, preventing access to VOx sites, without a loss of activity. Studies on CNFs confirm that carbonaceous materials act as catalysts in this reaction. Carbon-based catalysts represent an important new class of potential catalysts for DH and ODH reactions

Trust among cybercriminals? Carding forums, uncertainty and implications for policing

At the beginning of the 21st Century, before the power of online social networking became apparent, several studies speculated about the likely structure of organised cybercrime (Mann and Sutton 1998; Brenner 2002). In the light of new data on cybercriminal organisations, this paper sets out to revisit their claims. In collaboration with the Serious Organised Crime Agency (SOCA), this paper examines the structure of organised cybercrime by analysing data from online underground markets previously in operation over the Internet. In order to understand the various structures of organised cybercrime which have manifested, theories are drawn from social psychology, organised crime and transaction cost economics (TCE). Since the focus is on how uncertainty is mitigated in trading among cybercriminals, uncertainty is treated as a cost to the transactions and is used as the unit of analysis to examine the mechanisms cybercriminals use to control two key sources of uncertainty: the quality of merchandise and the identity of the trader. The findings indicate that carding forums facilitate organised cybercrime because they offer a hybrid form of organisational structure that is able to address sources of uncertainty and minimise transaction costs to an extent that allows a competitive underground market to emerge. The findings from this study can be used to examine other online applications that could facilitate the online underground economy

Copula Theory: An Introduction

Abstract In this survey we review the most important properties of copulas, several families of copulas that have appeared in the literature, and which have been applie