Electron affinities of p-benzoquinone, p-benzoquinone imine and p-benzoquinone diimine, and spin densities of their p-benzosemiquinones computed by several quantum chemical models

Restricted and unrestricted (U) Hartree-Fock (HF), second-order M?ller-Plesset perturbation (MP2), density functional (DF), hybrid HF/DF and semiempirical (half-electron (HE) method) models have been used to calculate adiabatic electron affinities (EAad values) of p-benzoquinone (I), p-benzoquinone imine (VI) and p-benzoquinone diimine (XI), as well as expectation values () and spin density distributions in the radical anions of I, VI and XI. The AM1/AM1-HE and ab initio calculated structures are found to be in accord with each other. The ROHF/6-31G(d) method gave the poorest EAad result. The UHF and UMP2 wave functions were found to be substantially spin contaminated (for the radicals) and the accuracies of the EAad values calculated were also poor. The use of molecular energies obtained after spin annihilation did not lead to significant improvement of the UHF and UMP2 results. In contrast to the ROHF, UHF and UMP2 results, the DF(USVWN, UBVWN, UBLYP) and hybrid HF/DF(UB3LYP) methods, as well as the AM1-HE, gave much better results. The calculated EAad values decreased, as predicted by most of the models, in the order EAad(I) > EAad(VI) > EAad(XI). The differences in the EAs, EAad(I)-EAad(VI) and EAad(I)-EAad(XI), were consistently predicted to be about 8-9 and 17-18 kcal/mol, respectively, by the DF, B3LYP and AM1-HE models. The performance of the PM3 and SAM1 models was not as good as the AM1 model. Of all the methods tested, the B3LYP/6-311G(d,p) model is concluded to give the most accurate quantitative trend (I(42.6) > VI(33.1) > XI(23.7)) in EAad. The predicted trend in EA can satisfactorily be rationalized by the calculated LUMO orbital energies, atomic charges and spin density distributions. Analysis of the spin density data predicts that phenoxyl- and anilino-type radical anions predominate in the p-benzosemiquinones of I and XI, respectively, while both phenoxyl- and anilino-type radicals contribute to the structure of the p-benzosemiquinone of VI, with the anilino-type predominating.     

If it looks like a spammer and behaves like a spammer,it must be a spammer: analysis and detection of microblogging spam accounts

Spam in online social networks (OSNs) is a systemic problem that imposes a threat to these services in terms of undermining their value to advertisers and potential investors, as well as negatively affecting users’ engagement. As spammers continuously keep creating newer accounts and evasive techniques upon being caught, a deeper understanding of their spamming strategies is vital to the design of future social media defense mechanisms. In this work, we present a unique analysis of spam accounts in OSNs viewed through the lens of their behavioral characteristics. Our analysis includes over 100 million messages collected from Twitter over the course of 1 month. We show that there exist two behaviorally distinct categories of spammers and that they employ different spamming strategies. Then, we illustrate how users in these two categories demonstrate different individual properties as well as social interaction patterns. Finally, we analyze the detectability of spam accounts with respect to three categories of features, namely content attributes, social interactions, and profile properties.     

Effective enhancement of electric and magnetic properties of PMMA/LiFe5O8 nanocomposites via magnetic treatment

Journal of Materials Science: Materials in Electronics - The present study presents a facile effective method to enhance the electric as well as the magnetic properties of polymer/ferrite...     

Response Times for Auditory and Vibrotactile Directional Cues in Different Immersive Displays

ABSTRACT

Using multisensory signals in advanced driver assistance is continuously increasing as a way to increase the attention and reduce the reaction time. It is essential that driver assistance system is capable of providing directional cues to the driver to direct his attention to the sides of the car as usually the focus is in front of the car. These signals could be for blind spot information, navigation, lane departure warning, collision warning, etc. This study investigated the effect of auditory and vibrotactile on directional attention in driver assistance systems. Moreover, two types of immersive displays were used in the driving simulation, namely the Head Mounted Display (HMD) and CAVE display, to study the effect of the type of display on the human performance. Lane Chang Task was used to assess the attention by measuring the response time to directional information. Vibrotactile and Auditory cues induced equal response times, meanwhile, vibrotactile signal was significantly gained higher satisfaction than auditory.     

Trust calibration of automated security IT artifacts: A multi-domain study of phishing-website detection tools

Phishing websites become a critical cybersecurity threat affecting individuals and organizations. Phishing-website detection tools are designed to protect users against such sites. Nevertheless, detection tools face serious user trust and suboptimal performance issues which require trust calibration to align trust with the tool’s capabilities. We employ the theoretical framework of automation trust and reliance as a kernel theory to develop the trust calibration model for phishing-website detection tools. We test the model using a controlled lab experiment. The results of our analysis show that users’ trust in detection tools can be calibrated by trust calibrators. Moreover, users’ calibrated trust has significant consequences, including users’ tool reliance, use, and performance against phishing websites.     

Auxetic Polymeric Bone Stent for Tubular Fractures: Design,Fabrication and Structural Analysis

Fracture fixation techniques, fracture management, and orthopedic trauma care have evolved, and various advancements have been made in the last 50 years. Minimally invasive biological osteosynthetic devices have the potential of transforming the prospects of orthopedic treatment. Internal fixation techniques offer tremendous advantages in the management of bone fractures. The main objective of this study was to fabricate a novel auxetic polymeric bone stent with potential applications in internal fixation procedures. A new “connected stars” geometry has been used for the fabrication of this device. After fabrication, the mechanical characterization of the auxetic bone stent was also carried out to study its properties and deformation behavior. The research work undertaken also assesses the potential for auxetic behavior of these tubular structures.