Users have adopted a wide range of digital technologies into their communication repertoire. It remains unclear why they adopt multiple forms of communication instead of substituting one medium for another. It also raises the question: What type of need does each of these media fulfill? In the present article, the authors conduct comparative work that examines the gratifications obtained from Facebook with those from instant messaging. This comparison between media allows one to draw conclusions about how different social media fulfill user needs. Data were collected from undergraduate students through a multimethod study based on 77 surveys and 21 interviews. A factor analysis of gratifications obtained from Facebook revealed six key dimensions: pastime, affection, fashion, share problems, sociability, and social information. Comparative analysis showed that Facebook is about having fun and knowing about the social activities occurring in one’s social network, whereas instant messaging is geared more toward relationship maintenance and development. The authors discuss differences in the two technologies and outline a framework based on uses and gratifications theory as to why young people integrate numerous media into their communication habits.

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Collision-induced dissociation (CID) of protonated YAGFL-NH2 leads to nondirect sequence fragment ions that cannot directly be derived from the primary peptide structure. Experimental and theoretical evidence indicate that primary fragmentation of the intact peptide leads to the linear YAGFLoxa b5 ion with a C-terminal oxazolone ring that is attacked by the N-terminal amino group to induce formation of a cyclic peptide b5 isomer. The latter can undergo various proton transfer reactions and opens up to form something other than the YAGFLoxa linear b5 isomer, leading to scrambling of sequence information in the CID of protonated YAGFL-NH2.

Despite concerns raised about the disclosure of personal information on social network sites, research has demonstrated that users continue to disclose personal information. The present study employs surveys and interviews to examine the factors that influence university students to disclose personal information on Facebook. Moreover, we study the strategies students have developed to protect themselves against privacy threats. The results show that personal network size was positively associated with information revelation, no association was found between concern about unwanted audiences and information revelation and finally, students' Internet privacy concerns and information revelation were negatively associated. The privacy protection strategies employed most often were the exclusion of personal information, the use of private email messages, and altering the default privacy settings. Based on our findings, we propose a model of information revelation and draw conclusions for theories of identity expression.

PRIVACY PROTECTION STRATEGIES ON FACEBOOKThe Internet privacy paradox revisitedThe privacy paradox describes people's willingness to disclose personal information on social network sites despite expressing high levels of concern. In this study, we employ the distinction between institutional and social privacy to examine this phenomenon. We investigate what strategies undergraduate students have developed, and their motivations for using specific strategies. We employed a mixed-methods approach that included 77 surveys and 21 in-depth interviews. The results suggest that, in addition to using the default privacy settings, students have developed a number of strategies to address their privacy needs. These strategies are used primarily to guard against social privacy threats and consist of excluding contact information, using the limited profile option, untagging and removing photographs, and limiting Friendship requests from strangers. Privacy strategies are geared toward managing the Facebook profile, which we argue functions as a front stage. This active profile management allows users to negotiate the need for connecting on Facebook with the desire for increased privacy. Thus, users disclose information, because they have made a conscious effort to protect themselves against potential violations. We conclude that there is a tilt toward social privacy concerns. Little concern was raised about institutional privacy and no strategies were in place to protect against threats from the use of personal data by institutions. This is relevant for policy discussions, because it suggests that the collection, aggregation, and utilization of personal data for targeted advertisement have become an accepted social norm.

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Metallochaperones are essential for the safe and targeted delivery of necessary yet toxic metal cofactors to their respective protein partners. In this study we examine the nickel-binding properties of the Escherichia coli protein SlyD, a factor that contributes to optimal nickel accumulation in this organism. This protein is also required for E. coli energy metabolism because it participates in the nickel insertion step during [Ni-Fe]-hydrogenase metallocenter assembly. Our study demonstrates that SlyD is a multiple nickel ion binding protein. The analysis of noncovalent metal-protein complexes via electrospray ionization mass spectrometry revealed that SlyD binds up to seven nickel ions in a noncooperative manner with submicromolar affinity (<2 microM, upper limit) and that the protein exists in a dynamic mixture of metalloforms that is dependent on the availability of nickel ions in solution. Structural analysis indicates that this metallochaperone undergoes small but distinct changes in the structure upon metal binding and that the nickel-binding sites are assembled through beta-turn formation. Although the C-terminal metal-binding domain is primarily responsible for metal chelation, we find that metal binding also perturbs the structure of the N-terminal domains. An investigation of the nickel sites by using X-ray absorption spectroscopy shows that SlyD binds nickel ions by adapting several different geometries and coordination numbers. Finally, the characterization of SlyD mutants demonstrates that the cysteine residues in the C-terminal domain confer tighter affinity as well as increased binding capacity to SlyD. On the basis of the presented data a model for nickel binding to SlyD as well as its role in nickel homeostasis is discussed.