Different behavior of nitrenes and carbenes on photolysis and thermolysis: Formation of azirine, ylidic cumulene, and cyclic ketenimine and the rearrangement of 6-phenanthridylcarbene to 9-phenanthrylnitrene

Flash vacuum thermolysis (FVT) of 9-azidophenanthrene 8, 6-(5-tetrazolyl)phenanthridine 18, and [1,2,3]triazolo[1,5-f]phenanthridine 19 yields 9-cyanofluorene 12 as the principal product and 4-cyanofluorene as a minor product. In all cases, when the product is condensed at or below 77 K, the seven-membered ring ketenimine 24 is detectable by IR spectroscopy (1932 cm(-1)) up to 200 K. Photolysis of Ar matrix isolated 8 at lambda = 308 or 313 nm generates at first the azirine 26, rapidly followed by the ylidic cumulene 27. The latter reverts to azirine 26 at lambda > 405 nm, and the azirine reverts to the ylidic cumulene at 313 nm. Nitrene 9 is observed by ESR spectroscopy following FVT of either azide 8, tetrazole 18, or triazole 19 with Ar matrix isolation of the products. Nitrene 9 and carbene 21 are observed by ESR spectroscopy in the Ar matrix photolyses of azide 8 and triazole 19, respectively.

Molecular dynamics simulation of organic-inorganic nanocomposites: Layering behavior and interlayer structure of organoclays

Isothermal-isobaric (NPT) molecular dynamics simulation has been performed to investigate the layering behavior and structure of nanoconfined quaternary alkylammoniums in organoclays. This work is focused on systems consisting of two clay layers and a number of alkylammoniums, and involves the use of modified Dreiding force field. The simulated basal spacings of organoclays agree satisfactorily with the experimental results in the literature. The atomic density profiles in the direction normal to the clay surface indicate that the alkyl chains within the interlayer space of montmorillonite exhibit an obvious layering behavior. The headgroups of long alkyl chains are distributed within two layers close to the clay surface, whereas the distributions of methyl and methylene groups are strongly dependent on the alkyl chain length and clay layer charge. Monolayer, bilayer, and pseudo-trilayer structures are found in organoclays modified with single long alkyl chains, which are identical to the structural models based on the measured basal spacings. A pseudo-quadrilayer structure, for the first time to our knowledge, is also identified in organoclays with double long alkyl chains. In the mixture structure of paraffin-type and multilayer, alkyl chains do not lie flat within a single layer but interlace, and also jump to the next layer in pseudo-trilayer as well as next nearest layer in pseudo-quadrilayer.

I'm a hypocrite, but so is everyone else: Group support and the reduction of cognitive dissonance

The impact of social support on dissonance arousal was investigated from a social identity view of dissonance theory. This perspective is seen as augmenting current conceptualizations of dissonance theory by predicting when normative information will impact on dissonance arousal and by indicating the availability of identity-related strategies of dissonance reduction. An experiment was conducted to induce feelings of hypocrisy under conditions of behavioral support or nonsupport. Group salience was either high or low, or individual identity was emphasized. As predicted, participants with no support from the salient in-group exhibited the greatest need to reduce dissonance through attitude change and reduced levels of group identification. Results were interpreted in terms of self being central to the arousal and reduction of dissonance.

Ethics and intervention: The 'humanitarian exception' and the problem of abuse in the case of Iraq

This article investigates the ethics of intervention and explores the decision to invade Iraq. It begins by arguing that while positive international law provides an important framework for understanding and debating the legitimacy of war, it does not cover the full spectrum of moral reasoning on issues of war and peace. To that end, after briefly discussing the two primary legal justifications for war (implied UN authorization and pre-emptive self-defence), and finding them wanting, it asks whether there is a moral 'humanitarian exceptions to this rule grounded in the 'just war' tradition. The article argues that two aspects of the broad tradition could be used to make a humanitarian case for war: the 'holy war' tradition and classical just war thinking based on natural law. The former it finds problematic, while the latter it argues provides a moral space to justify the use of force to halt gross breaches of natural law. Although such an approach may provide a moral justification for war, it also opens the door to abuse. It was this very problem that legal positivism from Vattel onwards was designed to address. As a result, the article argues that natural law and legal positivist arguments should be understood as complementary sets of ideas whose sometimes competing claims must be balanced in relation to particular cases. Therefore, although natural law may open a space for justifying the invasion of Iraq on humanitarian terms, legal positivism strictly limits that right. Ignoring this latter fact, as happened in the Iraq case, opens the door to abuse.

Social identity, self-categorization, and the communication of group norms

We articulate the role of norms within the social identity perspective as a basis for theorizing a number of manifestly communicative phenomena. We describe how group norms are cognitively represented as context-dependent prototypes that capture the distinctive properties of groups. The same process that governs the psychological salience of different prototypes, and thus generates group normative behavior, can be used to understand the formation, perception, and diffusion of norms, and also how some group members, for example, leaders, have more normative influence than others. life illustrate this process across a number of phenomena and make suggestions for future interfaces between the social identity perspective and communication research. We believe that the social identity approach represents a truly integrative force for the communication discipline.