Transfer film evolution and its role in promoting ultra-low wear of a PTFE nanocomposite

Polytetrafluoroethylene (PTFE) is an important solid lubricant with an unusually high wear rate. For a half-century, fillers have been used to reduce PTFE wear by >100× with >10% loading through hypothesized mechanisms involving mechanical load support, crack arresting, and transfer film adhesion. More recently it was discovered that specific nanoparticles provide a unique nanoscale reinforcement mechanism enabling unprecedented wear reductions of 10,000× with as little as 0.1% nano-fillers. Although the mechanisms responsible for this dramatic improvement remain unclear, there is substantial evidence that the transfer film plays a critical role. This paper uses interrupted microscopy measurements to investigate the evolution of transfer film development for an ultra-low wear PTFE nanocomposite. The run-in wear rates were similar to those of more traditional PTFE composites and transfer films consisted of large plate-like debris. Although the run-in wear rate and debris size decreased monotonically with distance, the run-in transfer films were removed each cycle. Detectible debris vanished and wear rates approached zero at an abrupt transition. During this ultra-low wear transition period, nanoscale and oxidized fragments of PTFE were transferred to the counterface. Most of these fragments persisted for the duration of the test and initiated the transfer film by progressively scavenging trace material from the bulk, growing into small islands, and merging with neighboring islands. The results of this study reflect a complex interplay involving elements of transfer film adhesion, chemistry, debris morphology, and mechanics.     

Vapor phase synthesis of hexagonal shaped single crystal yttria stabilized zirconia nanoparticles using CO2 laser

Growth of hexagonal shaped single crystal yttria stabilized zirconia nanoparticles has been observed in the vapors emanating from solid targets vaporized using CO₂ laser in CW and pulsed modes of operation. The mean size and yttrium concentration in these nanoparticles are found to be in the range of 5–40 nm and ～10.4–11.6 wt% respectively, which depend on the laser power density and the gaseous environment used during the growth process. Nanoparticles synthesized with pulsed mode of laser operation were found to be smaller in size compared to those generated in the CW mode. It was also found that formation of these nanoparticles was more pronounced in helium gas environment compared to those in nitrogen and argon. X-ray and electron diffraction studies showed that in all experimental conditions the generated nanoparticles were in cubic phase. From high resolution TEM it was observed that the nanoparticles with identical orientations coalesced with each other in line with the oriented attachment theory.     

Stress dependent band gap shift and valence band studies in ZnO nanorods

ZnO nanorods are grown on seedless and ZnO seeded glass substrates using chemical solution method and their structural, morphological, optical and valence band studies have been carried out. On seedless substrate horizontal nanorods are observed whereas for the seeded substrates vertically aligned hollow and solid nanorods grows. X-ray diffraction analysis revealed the presence of tensile stress in the vertical nanorods. Blue shift has been observed in the band gap of the vertical nanorods as compared to the horizontal nanorods which is attributed to the presence of tensile stress in the vertically aligned nanorods. Photoluminescence spectra revealed the dominance of Zinc vacancies (V(Zn)) related defects in the nanorods and oxygen defects are found to be higher in the vertically aligned nanorods as compared to the horizontal nanorods. The difference between the Fermi level and valence band maxima for horizontal, hollow vertical and solid vertical nanorods are found to be approximately 0.56 eV, approximately 0.70 eV and approximately 0.92 eV respectively indicating the possibility of p-type of conduction in the nanorods which has been attributed to presence of V(Zn) defects in the ZnO nanorods.     

Malignant peripheral nerve sheath tumor of bone in children and adolescents

In situ vascular endothelium is characterized by many cytoplasmic vesicles (caveolae) and vacuoles. In venules these are organized into prominent clusters called vesiculo-vacuolar organelles or VVOs. VVOs provide an important pathway for plasma protein extravasation in response to vasoactive mediators. In contrast, cultured endothelial cells isolated from many sources lack VVOs and generally have few caveolae. Our goal was to preserve VVOs in cultured endothelium. Bovine adrenal microvascular endothelial cells (BCEs) cultured on floating Matrigel-collagen Type I gels with vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) exhibited typical VVOs by electron microscopy. Both in vivo and in culture VVOs were caveolin-positive by immunoelectron microscopy. On the basis of caveolin immunostaining, VVOs could also be detected by light (confocal) microscopy. When BCEs were cultured without VPF/VEGF, caveolin staining was finely punctate and electron microscopy confirmed the near absence of VVOs. BCE VVOs were sensitive to N-ethylmaleimide. Other types of endothelium cultured on Matrigel-collagen gels with or without VPF/VEGF exhibited few caveolae and no VVOs. Therefore, preservation of VVOs in cultured endothelium required a specific combination of endothelial cells (BCEs), surface matrix (Matrigel-collagen), and growth factor (VPF/VEGF). These endothelial cells should be useful for in vitro studies of trans-endothelial transport.     

Building the perfect beast: dreams of a grand unified protocol

From the infinite world of protocol designs-yet-to-be, the paper focuses on an IETF Birds-of-a-Feather proposal for an Application Core (ApplCore) protocol. ApplCore would identify common problems encountered in application-level protocol development and then design one simple core protocol to solve these problems based on the successes and failures of already deployed IETF protocols-in effect, an application-layer TCP     

Optimisation of the hybrid renewable energy system by HOMER,PSO and CPSO for the study area

This study is based on simulation and optimisation of the renewable energy system of the police control room at Sagar in central India. To analyse this hybrid system, the meteorological data of solar insolation and hourly wind speeds of Sagar in central India (longitude 78°45′ and latitude 23°50′) have been considered. The pattern of load consumption is studied and suitably modelled for optimisation of the hybrid energy system using HOMER software. The results are compared with those of the particle swarm optimisation and the chaotic particle swarm optimisation algorithms. The use of these two algorithms to optimise the hybrid system leads to a higher quality result with faster convergence. Based on the optimisation result, it has been found that replacing conventional energy sources by the solar–wind hybrid renewable energy system will be a feasible solution for the distribution of electric power as a stand-alone application at the police control room. This system is more environmentally friendly than the conventional diesel generator. The fuel cost reduction is approximately 70–80% more than that of the conventional diesel generator.     

Water Quality Prediction of Gangapur Reservoir (India) Using LS‐SVM and Genetic Programming

Water quality analysis involves analysis of physio‐chemical, biological and microbiological parameters that reflect the abiotic and biotic status of ecosystems. This assessment facilitates planning for the utilization, antipollution and conservation strategies for sustainable use of aquatic ecosystem. Many mathematical models are available for predicting water quality. They have complex structures and require detailed information about sources and receptors, which are difficult and non‐economical. Difficulties in applying mathematical models promote the application of alternative approaches for data‐driven techniques for analysis of the results. The present study focuses on water quality predictions for the Gangapur Reservoir for a 30 days in advance scenario, using genetic programming (GP) and least square support vector machines (LS‐SVMs). A data period of 11 years (2000–2011) of Gangapur Reservoir temporal water quality was evaluated. The data were taken from a single sampling point representing climatological, hydrological and surface water quality measurements. One of the most important steps in application of data‐driven technique is selection of significant input parameters. Genetic programming equations were used for selecting significant input parameters. These significant input parameters are used for 30 days advance predictions of faecal coliform. A performance analysis of GP and LS‐SVM models was carried out with the help of coefficient of determination, root‐mean‐square error and correlation coefficient. In the absence of availability of data, a typical situation for Indian case studies, the model runs were conducted with the use of available parameters. The developed models, along with their performance indicators, also are discussed.     

Utilizing multiscale local binary pattern for content-based image retrieval

Multimedia Tools and Applications - With the development of different image capturing devices, huge amount of complex images are being produced everyday. Easy access to such images requires proper...     

Reliability analysis of a conveyor belt system, with only one server, subject to failures and idleness after repair

A converyor belt system is subjected to random failure and subsequently put under repair. After repair, it enters the idle state from where it is recalled to the working state. The server is allowed to idle when the conveyor is in failed state or in idle state (after repair). The idleness of the conveyor has not been considered in the past. The server is idle also when there is no unit in the queue for service. In this paper, the reliability of such a conveyor system has been analysed. The various joint probability transforms are obtained by the use of Laplace transforms and the generating function technique. These transforms, on inversion, yield all the probability functions for determination of reliability of the conveyor system.