Synthesis and physicochemical study of polyester polyols of epoxy resin of 2,4,6‐tris(4‐hydroxyphenyl)‐1,3,5‐triazine and their polyurethanes

Polyester polyols of ricinoleic acid (ETPRA), oleic acid, linoleic acid (ETPLA), and rosin (ETPR) and epoxy resin of 2,4,6‐tris(4‐hydroxyphenyl)‐1‐3‐5‐triazine (ETP) and their polyurethanes (PUs) were synthesized and characterized by Fourier transform infrared spectroscopy, NMR, differential scanning calorimetry, and thermogravimetric analysis techniques. The PU films showed the following density order: ETPRPU600 > ETPRAPU600 > ETPLAPU600. ETPLAPU600 showed good tensile strength and volume resistivity values compared to ETPRAPU600 and ETPRPU600. All three PUs showed good electric strength. ETPLAPU600 showed almost double the electric strength of ETPRAPU600 and ETPRPU600. The incorporation of soft‐segment poly(ethylene glycol) 600 into PU chains resulted in the flexibility of the films. The PU films showed a high water absorption tendency in water, acidic, and saline environments, and they degraded in an alkaline environment. The weight gain tendency of the films was due to surface solvolysis and was also probably due to microcrack formation. The polyester polyols and PUs were thermally stable up to about 167–221 and 184–214°C, respectively, and followed multistep degradation reactions with either fractional or integral order (0.43–2.71) degradation kinetics. Thus, the structure of the PUs affected the studied physicochemical properties of the films. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40203.     

Structural analysis of graphene oxide/silver nanocomposites: optical properties,electrochemical sensing and photocatalytic activity

In the present study, graphene oxide/silver (GO/Ag) nanocomposites were synthesized via a facile simple one pot chemical reduction method using ethylene glycol/sodium borohydrate (EG/NaBH₄) as solvent and reducing agent. GO was selected as a substrate and stabilizer to prepare GO/Ag nanocomposites. The synthesized GO/Ag nanocomposites were characterized by a series of techniques. Highly monodispersed stable crystalline silver nanoparticles having a face-centered cubic (fcc) phase were confirmed by X-ray powder diffraction (XRD) on GO signature. Scanning electron microscopy images showed that Ag nanoparticles are deposited on the GO sheet with a narrow size distribution. Transmission electron microscopy observations revealed that large numbers of Ag nanoparticles were uniformly distributed on GO sheet and well separated with an average size of 18 nm. Ultraviolet–visible (UV–Vis) spectroscopic results showed the peak of GO and surface plasmon resonance (SPR) of Ag nanoparticles. The SPR property of GO/Ag nanocomposites showed that there was an interaction between Ag nanoparticles and GO sheet. The intensities of the Raman signal of GO/Ag nanocomposites are gradually increased with attachment of Ag nanoparticles i.e. there is surface-enhanced Raman scattering activity. Electrochemical investigations indicated that the nanocomposites possessed an excellent performance for detecting towards 4-nitrophenol. An application of the obtained GO/Ag nanocomposites as a catalyst in the reduction of 4-nitrophenol to 4-aminophenol by NaBH₄ was demonstrated. The GO/Ag nanocomposites exhibited high activity and stability for the catalytic reduction of 4-nitrophenol. The prepared GO/Ag nanocomposites act as photo-catalysts.     

QoS and resource management in distributed interactive multimedia environments

Quality of Service (QoS) is becoming an integral part of current ubiquitous Distributed Interactive Multimedia Environments (DIMEs) because of their high resource and real-time interactivity demands. It is highly influenced by the management techniques of available resources in these cyber-physical environments. We consider QoS and resource management influenced by two most important resources; the computing (CPU) and networking resources. In this paper, we survey existing DIME-relevant QoS and resource management techniques for these two resources, present their taxonomy, compare them, and show their impacts on DIMEs. Finally, we discuss appropriateness of those techniques in a sample DIME scenario.     

Future IoT‐enabled threats and vulnerabilities: State of the art,challenges, and future prospects

In the recent era, the security issues affecting the future Internet‐of‐Things (IoT) standards has fascinated noteworthy consideration from numerous research communities. In this view, numerous assessments in the form of surveys were proposed highlighting several future IoT‐centric subjects together with threat modeling, intrusion detection systems (IDS), and various emergent technologies. In contrast, in this article, we have focused exclusively on the emerging IoT‐related vulnerabilities. This article is a multi‐fold survey that emphasizes on understanding the crucial causes of novel vulnerabilities in IoT paradigms and issues in existing research. Initially, we have emphasized on different layers of IoT architecture and highlight various emerging security challenges associated with each layer along with the key issues of different IoT systems. Secondly, we discuss the exploitation, detection, and defense methodologies of IoT malware‐enabled distributed denial of service (DDoS), Sybil, and collusion attack capabilities. We have also discussed numerous state‐of‐the‐art strategies for intrusion detection and methods for IDS setup in future IoT systems. Third, we have presented a brief classification of existing IoT authentication protocols and a comparative analysis of such protocols based on different IoT‐enabled cyber attacks. For conducting a real‐time future IoT research, we have presented some emerging blockchain solutions. We have also discussed a comparative examination of some of the recently developed simulation tools and IoT test beds that are characterized based on different layers of IoT infrastructure. We have also outlined some of the open issues and future research directions and also facilitate the readers with broad classification of existing surveys in this domain that addresses several scopes related to the IoT paradigm. This survey article focuses in enabling IoT‐related research activities by comparing and merging scattered surveys in this domain.     

Memorial consequences of answering SAT II questions.

Many thousands of students take standardized tests every year. In the current research, we asked whether answering standardized test questions affects students' later test performance. Prior research has shown both positive and negative effects of multiple-choice testing on later tests, with negative effects arising from students selecting incorrect alternatives on multiple-choice tests and then believing they were correct (Roediger & Marsh, 2005). In the current experiments, undergraduates and high school students answered multiple-choice questions retired from SAT II tests (that are no longer in the testing pool) on biology, chemistry, U.S. history, and world history, and later answered cued-recall questions about these subjects. In 3 experiments, we observed positive testing effects: More final cued-recall questions were answered correctly if the items had appeared on the initial multiple-choice test. We also sometimes observed negative testing effects: intrusions of multiple-choice distractors as answers on the final cued-recall test. Students who scored well on the initial test benefited from taking the test, but lower achieving students showed either less benefit (undergraduates) or costs from the testing (high school students). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sesame Oil and Rice Bran Oil Ameliorates Adjuvant-Induced Arthritis in Rats: Distinguishing the Role of Minor Components and Fatty Acids

Though present in small amounts, the minor constituents of dietary oils may supplement the dietary therapies for rheumatoid arthritis (RA). Hence, in the present study, we assessed the effect of minor constituents from sesame oil (SO) and rice bran oil (RBO) and their fatty acids on the severity of adjuvant‐induced arthritis in experimental rats. Rats were gavaged with 1 mL of SO or RBO or groundnut oil (GNO, control) with or without its minor components for a period 15 days before and 15 days after the induction of arthritis. Oxidative stress, markers of RA, eicosanoids, cytokines, paw swelling and joint integrity were measured in experimental and control rats. Results demonstrated that native SO and RBO but not SO and RBO stripped of their minor components decreased severity of paw inflammation, oxidative stress (lipid peroxides, protein carbonyls, nitric oxide), RA markers (RF and CRP), inflammatory eicosanoids (PGE₂, LTB₄ and LTC₄) and cytokines (IL‐1β, IL‐6, MCP‐1 and TNF‐α) compared to control rats. Native SO and RBO inhibited hydrolytic enzymes (collagenase, elastase and hyaluronidase) in the synovial tissue compared to SO and RBO without minor components. The arthritic scores assessed based on the digital and X‐ray images indicated that native oils but not those without their minor components reduced the paw swelling and bone loss. Our results indicated that minor components of SO and RBO possess a significant degree of an anti‐arthritic effect and are responsible for down regulating inflammation in the experimentally induced arthritis in rats.     

Test-enhanced learning in a middle school science classroom: The effects of quiz frequency and placement.

Typically, teachers use tests to evaluate students' knowledge acquisition. In a novel experimental study, we examined whether low-stakes testing (quizzing) can be used to foster students' learning of course content in 8th grade science classes. Students received multiple-choice quizzes (with feedback); in the quizzes, some target content that would be included on the class summative assessments was tested, and some of the target content was not tested. In Experiment 1, three quizzes on the content were spaced across the coverage of a unit. Quizzing produced significant learning benefits, with between 13% and 25% gains in performance on summative unit examinations. In Experiments 2a and 2b, we manipulated the placement of the quizzing, with students being quizzed on some content prior to the lecture, quizzed on some immediately after the lecture, and quizzed on some as a review prior to the unit exam. Review quizzing produced the greatest increases in exam performance, and these increases were only slightly augmented when the items had appeared on previous quizzes. The benefits of quizzing (relative to not quizzing) persisted on cumulative semester and end-of-year exams. We suggest that the present effects reflect benefits accruing to retrieval practice, benefits that are well established in the basic literature. (PsycINFO Database Record (c) 2011 APA, all rights reserved)