Microstructural,strength, and creep characterization of Sylramic™, Sylramic™-iBN and super Sylramic™-iBN SiC fibers

The chemical composition, microstructure, strength, and thermal stability of polymer-derived Sylramic? SiC fibers fabricated by Dow Corning and COI Ceramics, Inc., and nitrogen-treated Sylramic? SiC fibers, referred to as Sylramic?-iBN and Super Sylramic?-iBN SiC fibers, were investigated and compared. The baseline Sylramic? SiC fibers fabricated by both vendors as well as the nitrogen-treated Sylramic? SiC fibers are composed mostly of β-SiC (～97 wt%) with small amounts of TiB₂ (～2 wt%), amorphous carbon (～1 wt%) and trace amounts of B₄C. Most of the amorphous carbon is segregated at the core/interior of the fibers. Both baseline and nitrogen-treated Sylramic? SiC fibers have similar grain size and pore size distribution, except for a thin layer of in-situ grown crystalline BN (30–70 nm) on the surface of Sylramic?-iBN and Super Sylramic?-iBN fibers. Wide variation in strength within a batch as well as between batches is observed in both baseline and nitrogen-treated Sylramic? SiC fibers but both types of fibers are microstructurally stable at temperatures to 1800 °C in argon and nitrogen environments compared to Nicalon?-S and Tyranno®-SA SiC fibers. Under the same creep condition, Super Sylramic?-iBN fibers show better creep resistance compared to Sylramic?, Sylramic?-iBN, Hi-Nicalon?-S, and Tyranno®-SA fibers. Possible reasons for strength variability and the mechanism of in-situ BN formation on Sylramic? SiC fibers are discussed.     

Characterization and in vitro-bioactivity of natural hydroxyapatite based bio-glass–ceramics synthesized by thermal plasma processing

Natural bovine hydroxyapatite/SiO₂–CaO–MgO glass–ceramics were produced using the transferred arc plasma (TAP) processing method. Homogeneous mixtures of HA/25 wt% SiO₂–CaO–MgO and HA/50 wt% SiO₂–CaO–MgO batches obtained by dry mixing the respective compositions in a ball mill were processed in argon plasma using the TAP torch at 5 kW for 1, 2 and 3 min, respectively. The synthesized glass–ceramic samples were studied for phase composition, microstructure and bioactivity. The phase study of the synthesized glass–ceramics revealed the formation of calcium phosphate silicate with traces of calcium silicate. The structural study by SEM revealed that the prepared samples possessed smooth glassy surface morphology. The in vitro-bioactivity of the TAP synthesized glass–ceramics was examined in simulated body fluid (SBF). The SBF test results confirmed the development of crystalline carbonated apatite phase after 12 days of immersion. The cytocompatibility was evaluated through human fibroblast cell proliferation. The fibroblasts culture results showed that the sample was non-toxic and promoted cell growth.     

Scalable Path Computation Flooding Approach for PCE‐Based Multi‐domain Networks

In this letter, we assess the scalability of a path computation flooding (PCF) approach to compute optimal end‐to‐end inter‐domain paths in a path computation element‐based multi‐domain network. PCF yields a drastically reduced network blocking probability compared to a blind per‐domain path computation but introduces significant network control overhead and path computation complexity. In view of this, we introduce and compare an alternative low overhead PCF (LoPCF) solution. From the obtained results, LoPCF leads to similar blocking probabilities to PCF while exhibiting around 50% path computation complexity and network control overhead reduction.     

Preliminary studies on the valorization of animal flour ash for the obtainment of active glasses

Animal flour ash, rich in phosphorous, calcium and alkaline oxides, has been used to formulate (i) controlled-release fertilizers, since they manage to release the nutrient elements (P, K) at a low rate, and (ii) bioactive glasses.     

Microvascular decompression in the treatment of essential trigeminal neuralgia

INTRODUCTION AND OBJECTIVE: We pretend to evaluate the surgical procedure and clinical results of microvascular decompression (MVD) of 21 patients suffering from essential trigeminal neuralgia between 1989 and 1997. PATIENTS AND METHODS: Selection criteria included: ineffectiveness of pharmacological treatment, good general condition, more than five years life expectancy, and do not have undergone ablative-lesive surgical procedures before. RESULTS: After a post-surgical follow-up of between three months and three years, it was obtained a 100% success rate of immediate pain relief, with only a 14.2% recurrence. There were no sequels as those typically found in lesive techniques as paresthesias and dysesthesias, painful and/or corneal anaesthesia and motor disorders. There were no deaths, although there were three cases of post-surgical complications. CONCLUSIONS: To evaluate the long-term results of different surgical techniques in the treatment of the essential trigeminal neuralgia is outstanding the patients satisfaction rate, which not only depends on pain relief and absence of recurrence, but also and very specially on the neurological deficiencies following the procedure. So, we consider that MVD is the most effective technique both in symptoms relief and neural functions and structures preservation, even though the possibility of appearance of complications following any major surgery.     

A longitudinal study of fallow dynamics in the UK Continental Shelf (UKCS)

This paper identifies the causes of and solutions to the problems posed by the fallow assets’ phenomenon in the UK Continental Shelf (UKCS). Using data available in the public domain, including the Fifth Fallow Release, the province's assets were grouped into two broad cross-sections of fallow and non-fallow assets, with further sub-divisions. The dependent variable of interest was the median fallow duration of the assets. Fallow duration was measured in two ways, namely those relating to censored and uncensored data. An empirical panel econometric model was formulated, estimated and simulated to establish the principal causal factors and the effective remedial policy measures. The model estimation results provide evidence that the interactive effects of the key influencing variables are stronger than their individual effects. Thus, the combined effects of reserves and distance from infrastructure have a greater weight on the fallow spell than their individual effects. Several policy simulation runs established that, contrary to some theoretical propositions, (a) stronger rather than weaker government intervention, on occasion, is preferable, and (b) price is not a central determinant of investment timing.     

Data reconciliation and optimal management of hydrogen networks in a petrol refinery

This paper describes the main problems associated to the management of hydrogen networks in petrol refineries and presents an approach to deal with them with the aim of operating the installation in the most profitable way. In particular, the problems of data reconciliation, economic optimization and interaction with the underlying basic control system are reviewed. The paper provides also a proposal for the implementation of the system and illustrates the approach with results obtained using real data from an industrial site.     

Laser Machining and Functional Applications of Glass‐Ceramic Materials

In this work a study of glass‐ceramic laser machining and some functional applications are presented. Firstly, both the effect produced by the machining method as well as how the modification of the reference position influence the machining results have been studied. Secondly, blind holes and special shape cross‐section blind holes have been created for functional purposes. A Q‐switched Nd:YAG laser at its fundamental wavelength of 1064 nm with pulse‐widths in the nanosecond range has been used. Morphology, depth, and volume obtained by machining grooves have been studied. The variation in the ablation yield when the position of the surface to be machined is modified has also been studied. The composition and microstructure of the machined areas have been described and discussed and thermal tests have been performed to check if the objectives of the functional applications have been achieved.