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The abuse of chat services by automated programs, known as chat bots, poses a serious threat to Internet users. Chat bots target popular chat networks to distribute spam and malware. In this paper, we first conduct a series of measurements on a large commercial chat network. Our measurements capture a total of 14 different types of chat bots ranging from(More)
A mobile ad hoc network (MANET) is one consisting of a set of mobile hosts capable of communicating with each other without the assistance of base stations. Earlier research has proposed several unipath routing protocols specifically on MANET. However, the single path is easily broken and needs to perform a route discovery process again due to the dynamic(More)
A series of porous silk fibroin-poly(vinyl alcohol) blend gels were prepared from corresponding aqueous mixtures by freeze- or air-drying, and their structure and mechanical properties were examined. The air-dried gels had higher crystallinity and much greater strengths than the freeze-dried gels, and therefore are suitable for mechanical uses. The(More)
BACKGROUND Several polymorphisms have been reported to be associated with irritable bowel syndrome (IBS), including C825T, the single nucleotide polymorphism (SNP), responsible for a truncated G protein β3 subunit (GNβ3), and the Vall158Met substitution in catechol-O-methyltransferase (COMT). We investigated the association between these mutations and the(More)
5-Cyanoimino-4-oxomethylene-4,5-dihydroimidazoles (1) (R at N1) have been discussed as possible intermediates in nitrosative guanine deamination, which are formed by dediazoniation and deprotonation of guaninediazonium ion. The parent system 1 (R = H) and its N1 derivatives 2 (R = Me) and 3 (R = MOM) are considered here. Protonation of 1-3, respectively,(More)
Studies on skin substitutes and dermal scaffolds have been extensively carried out in the past several decades and some commercial products derived from collagen and polymers have been in marketing. Yet little research on silk fibroin based dermal scaffolds and products has been reported so far. In the present study, therefore, porous silk fibroin scaffolds(More)
A mobile ad hoc network (MANET) is one consisting of a set of mobile hosts capable of communicating with each other without the assistance of base stations. Earlier research has proposed several unipath routing protocols specifically on MANET, but most studies have not focused on the limitations of battery resource. To alleviate these problems, a new(More)
Since nodes in the mobile ad hoc networks (MANETs) network move freely and randomly, routes often get disconnected. The major challenge for MANETs is therefore to implement routing protocols that must respond to changes in the network topology in order to maintain and reconstruct the routes in a timely manner as well as to establish reliable routes. In this(More)
The nucleophilic substitution of N2 in benzenediazonium ion 1 by one H2O molecule to form protonated phenol 2 has been studied with ab initio (RHF, MP2, QCISD(T)//MP2) and hybrid density functional (B3LYP) methods. Three mechanisms were considered: (a) the unimolecular process SN1Ar with steps 1 --> Ph+ + N2 and Ph+ + H2O --> 2, (b) the bimolecular process(More)