Optically pumped CW fir laser: New submillimeter laser emissions from CH2DOH, CH3I, CD3I, and trioxymethylene

We obtained twelve new far infrared laser transitions by optically pumping the CH₂DOH, CH₃I, CD₃I and Trioxymethylene molecules with a CW CO₂ laser having a tunability range of 280 MHz. We measured the wavelength, polarization, relative intensity and pump offset relative to the CO₂ center frequency for all the new lines.     

Cathodic protection with localised galvanic anodes in slender carbonated concrete elements

A combined experimental and numerical investigation was carried out with the aim of determining whether few localised galvanic anodes per unit length could protect the reinforcement of slender carbonated concrete elements, exposed to atmospheric conditions, which could not be repaired with traditional methods. Initially, the cathodic behaviour of steel under galvanostatic polarisation was determined on small-size specimens obtained from a real element. A correlation of potential versus applied current was obtained. The current distribution in slender elements was then determined through finite elements simulations, considering various scenarios of carbonation and humidity. Results showed that, in spite of the high electrical resistivity of carbonated concrete, anodes with spacing of 0.45 m are enough to protect corroding reinforcement in most exposure conditions, even in thin parts of element. Estimated anode durations were of the order of several years or even decades; however, it was shown that also reinforcement in dry (carbonated or alkaline) concrete, which does not need to be protected, contributes to anode consumption. Although other aspects play a role on the performance of a cathodic protection system (such as the effectiveness of anode-encasing material and of electrical connection to reinforcement), the results obtained are supportive of a repair strategy based on the use of localised galvanic anodes and can be generalised to slender elements exposed to atmospheric conditions suffering carbonation induced corrosion.     

On the Use of Silicon Nitride in Catalysis

Silicon nitride has very good thermal and chemical stability, as well as high thermal conductivity compared to oxide materials, which are commonly used as catalyst supports. In exothermic reactions working at high temperature, this facilitates heat transfer and thus limits the formation of local hot spots, which are often responsible for structural modification of the support in addition to sintering of active phases. However, it is only recently that this material has been considered for application as a catalyst support for high temperature reactions. It is now established that silicon nitride can be a good support for catalytically active phases. Its range of application is continually expanding (e.g., partial/total oxidation of methane, hydrogenation and dehydrogenation reactions, photocatalysis, base catalysis, etc.).     

An experimental and numerical study on omega stringer debonding

Omega stringers offer interesting structural capabilities and are expected on future aircraft fuselages. In postbuckling mode, the final failure of these structures may occur by stringer debonding between stringer flanges and the skin of the fuselage. In this study, it is demonstrated that the use of fracture mechanics allows to predict skin/omega stringer separation under multiple load cases. Three different load cases and experiments are presented allowing a debonding to start at different locations: at free flange edges or at the inner radius of the omega. Firstly, a skin/stringer configuration subjected to three point bending following the longitudinal axis of the stringer was tested. For this configuration, a numerical study was made and shows the influence of a refined mesh taking into account resin fillets. Secondly, new specimens were obtained by cutting into slices the longitudinal specimen. Those specimens were subjected to four points bending. It has been shown that the upper rolls position of the test jig could modify the debonding location. Numerical models have allowed to determine accurately the debonding location and the associated load level. For some specimens, resin fillets were removed from the flange tips and their effect were assessed numerically and experimentally.     

Cathodic protection of new and old reinforced concrete structures

Current and potential distributions measured on concrete slabs and simulated by computer modelling are discussed in relation with the application of cathodic protection to new reinforced structures as a corrosion preventive method. The results show high penetration of cathodic protection over the depth of uncontaminated concrete, so that even a rebar relatively distant from the anode can be polarized, whereas the penetration is limited to the rebars near to the anode in chloride contaminated slabs with corroding rebars. The great throwing power and the wide range of protection potentials for uncorroding concrete structure enable safe application of the cathodic protection even to new prestressed structures.     

A New Approach to High Resolution Timing with Photomultipliers

A new technique (Double Sampling) of photomultiplier pulse processing is studied in order to improve the time resolution. Two time references, t1, and t2, are obtained from two different processing systems, into which the fast pulse of the photomultiplier is fed. If the condition: (t1 - t2) -?t < (t1 -t2) < (t1 - t2) + ?t is satisfied, the pulse is accepted for the time analysis. ?t is a predetermined parameter of the proposed system. A theoretical study has been carried out in order to compare this processing method with the ones already used.     

An assessment of interventions for improving communication and trust in cost benefit analysis processes

Evaluation literature suggests that assessments of integrated transport plans should be an inclusive dialogue, for which it is crucial that participants communicate with and trust each other. However, cost benefit analysis (CBA) of integrated transport plans is often characterized by communication deficits and distrust among plan owners and evaluators. A literature review suggested five communication and trust-building interventions and related mechanisms that might improve this. In this paper, we have tested the efficacy of these five communication and trust-building interventions by applying them in an experiential study with two sequential cases, representing ‘close to real’ situations. The research aimed to develop field-tested knowledge to address the aforementioned class of CBA process problems. The research demonstrated how the five interventions could facilitate an exchange of information, knowledge and experiences, which – according to the participants – will increase the effectiveness of the CBA. Furthermore, it illustrated that a communication and trust-building strategy such as the one tested might be a useful complement to CBA practices, if adapted to the characteristics of the specific assessment process and planning context.     

Gastroprotective effect of a type I arabinogalactan from soybean meal

A highly purified type I arabinogalactan (AG) from soybean meal was prepared. It contained galactose, arabinose, galacturonic acid and rhamnose in a 52:41:4:3 molar ratio and had M_w 124,000 g/mol. Methylation analysis and ¹³C NMR spectroscopy indicated that AG is constituted by a (1→4)-linked β-Galp main chain with substituents of α-Araf at O-3, which are in turn substituted at O-5, O-3,5, and O-2,5. It is probably linked to O-4 of some rhamnosyl units of a type I rhamnogalacturonan, formed by repeating (1→4)-α-D-GalpA-(1→2)-α-L-Rhap groups. AG significantly inhibited ethanol-induced gastric lesions in rats at an ED₅₀ of 35 mg/kg, indicating that it has a gastroprotective effect.