Materials Selection, Synthesis, and Dielectrical Properties of PVC Nanocomposites

Materials selection process for electrical insulation application was carried out using Cambridge Engineering Selector (CES) program. Melt mixing technique was applied to prepare polyvinyl-chloride- (PVC-) nanofumed silica and nanomontmorillonite clay composites. Surface analysis and particles dispersibility were examined using scanning electron microscope. Dielectrical properties were assessed using Hipot tester. An experimental work for dielectric loss of the nanocomposite materials has been investigated in a frequency range of 10 Hz–50 kHz. The initial results using CES program showed that microparticles of silica and clay can improve electrical insulation properties and modulus of elasticity of PVC. Nano-montmorillonite clay composites were synthesized and characterized. Experimental analyses displayed that trapping properties of matrix are highly modified by the presence of nanofillers. The nanofumed silica and nanoclay particles were dispersed homogenously in PVC up to 10% wt/wt. Dielectric loss tangent constant of PVC-nanoclay composites was decreased successfully from 0.57 to 0.5 at 100 Hz using fillers loading from 1% to 10% wt/wt, respectively. Nano-fumed silica showed a significant influence on the electrical resistivity of PVC by enhancing it up to 1 × 1011 Ohm·m

A high-resolution versatile focused ion implantation platform for nanoscale engineering

The ability to spatially control and modify material properties on the nanoscale, including within nanoscale objects themselves, is a fundamental requirement for the development of advanced nanotechnologies. The development of a platform for nanoscale advanced materials engineering (P-NAME) designed to meet this demand is demonstrated. P-NAME delivers a high-resolution focused ion beam system with a coincident scanning electron microscope and secondary electron detection of single-ion implantation events. The isotopic mass-resolution capability of the P-NAME system for a wide range of ion species is demonstrated, offering access to the implantation of isotopes that are vital for nanomaterials engineering and nanofunctionalization. The performance of the isotopic mass selection is independently validated using secondary ion mass spectrometry (SIMS) for a number of species implanted into intrinsic silicon. The SIMS results are shown to be in good agreement with dynamic ion implantation simulations, demonstrating the validity of this simulation approach. The wider performance capabilities of P-NAME, including sub-10 nm ion beam imaging resolution and the ability to perform direct-write ion beam doping and nanoscale ion lithography, are also demonstrated

Brazilian Consensus on Photoprotection

Brazil is a country of continental dimensions with a large heterogeneity of climates and massive mixing of the population. Almost the entire national territory is located between the Equator and the Tropic of Capricorn, and the Earth axial tilt to the south certainly makes Brazil one of the countries of the world with greater extent of land in proximity to the sun. The Brazilian coastline, where most of its population lives, is more than 8,500 km long. Due to geographic characteristics and cultural trends, Brazilians are among the peoples with the highest annual exposure to the sun. Epidemiological data show a continuing increase in the incidence of nonmelanoma and melanoma skin cancers. Photoprotection can be understood as a set of measures aimed at reducing sun exposure and at preventing the development of acute and chronic actinic damage. Due to the peculiarities of Brazilian territory and culture, it would not be advisable to replicate the concepts of photoprotection from other developed countries, places with completely different climates and populations. Thus the Brazilian Society of Dermatology has developed the Brazilian Consensus on Photoprotection, the first official document on photoprotection developed in Brazil for Brazilians, with recommendations on matters involving photoprotection

The incidence and nature of injuries sustained on grass and 3rd generation artificial turf: A pilot study in elite Saudi National Team footballers

Purpose of the study: To compare the incidence, severity and nature of injuries sustained by Saudi National Team footballers during match-play and training on natural grass and 3rd generation (3G) artificial turf. Method: Injury data was collected on all Saudi National Team players competing at the Gulf Cup (Yemen December 2010: 3G) and the Asian Cup (Qatar January 2011; grass). A total of 49 players were studied (mean±SD; Age 27±4yr; body mass 71.4±6.7kg; height 176.8±6.3cm; professional playing experience 9±3yr) of which 31 competed at the Gulf Cup, 32 at the Asian Cup (14 at both). A prospective cohort design was used to investigate the incidence, nature and severity of injuries sustained with data collected using a standardised injury questionnaire. All data were collected by the team physiotherapist with the definition of injury set at any injury that required player and clinician contact. Injury and exposure data were collected and reported for games, training and all football activity. Results: A total of 82 injuries [incidence - 56.1 per 1000h total game and training exposure] were recorded at the Asian Cup (grass) and 72 injuries [incidence - 37.9 per 1000h total game and training exposure] were recorded at the Gulf Cup (3G). Incidence data for training, game and all football exposure injury rates were higher when playing on grass. The vast majority of injuries on both surfaces were very minor that, whilst requiring medical attention, did not result in loss of match/training exposure. Injuries that resulted in 1-3 days absence from training or game play had similar incidence rates (Grass: 7.4 vs. 3G: 7.4 injuries per 1000h exposure). More severe injuries were less frequent but with a higher incidence when playing on grass. Lower limb injuries were the most common in both tournaments with a higher incidence on grass (Grass: 14.2 vs. 3G: 7.9 injuries per 1000h exposure). Muscle injuries were the most frequent of all injuries with similar incidence rates on both surfaces (Grass: 5.4 vs. 3G: 4.7 injuries per 1000h exposure). Injuries that involved player contact were also more common on grass (Grass: 11.5 vs. 3G: 3.2 injuries per 1000h exposure). Conclusion: Whether reporting all injuries or just those that prevented players from taking part in training or match play, injury incidence rates were generally higher when Saudi National Team footballers played on grass than on 3G artificial surface. Although this is a small study, the unique quasi-repeated measures study design with elite Saudi National Team footballers, adds to the current belief that 3G artificial turf does not increase injury risk in football.</p

A Client Bootstrapping Protocol for DoS Attack Mitigation on Entry Point Services in the Cloud

This paper presents a client bootstrapping protocol for proxy-based moving target defense system for the cloud. The protocol establishes the identity of prospective clients who intend to connect to web services behind obscure proxy servers in a cloud-based network. In client bootstrapping, a set of initial line of defense services receive new client requests, execute an algorithm to assign them to a proxy server, and reply back with the address of the chosen proxy server. The bootstrapping protocol only reveals one proxy address to each client, maintaining the obscurity of the addresses for other proxy servers. Hiding the addresses of proxy servers aims to lower the likelihood that a proxy server becomes the victim of a denial-of-service (DoS) attack. Existing works address this problem by requiring the solution of computationally intensive puzzles from prospective clients. This solution slows the progression of attacks as well as new clients. This paper presents an alternative idea by observing that limited capacity of handling initial network requests is the primary cause of denial-of-service attacks. Thus, the suggested alternative is to utilize cost-effective high-capacity networks to handle client bootstrapping, thus thwarting attacks on the initial line of defense. The prototype implementation of the protocol using Google’s firebase demonstrates the proof of concept for web services that receive network requests from clients on mobile devices