Development of thermal fatigue damage in 1CrMoV rotor steel

Crack initiation endurances have been determined for a 1CrMoV rotor steel in uniaxial service cycle thermo-mechanical fatigue (TMF) tests formulated to simulate a range of steam turbine start cycles with a maximum temperature of 565 °C. The experimental details for these TMF tests are described.Post test inspection has been employed to characterise the associated thermal fatigue damage mechanisms for the steel which are observed to be dependent on the magnitude of the thermal transient in the TMF cycle.The lowest resistance to thermal fatigue damage development occurs in these tests when the conditions determine that the rate of creep damage accumulation below the surface exceeds the rate of fatigue crack development at the surface.     

Collagen orientation by X-ray pole figures and mechanical properties of media carotid wall

Many natural collagen containing materials are highly extensible composites and their mechanical behaviour will depend on the amount of collagen fibres present, the mechanical properties of the fibres and their distribution and orientation. A characteristic feature of these materials is that the fibrous collagen network can change orientation during stretching and hence the mechanical response of the tissues is a non-linear function of stress. In order to study the effect of fibre orientation, samples of carotid artery have been prestrained by given amounts in the hydrated state and then allowed to dry. The mean orientation of the fibres has been derived using pole figures obtained from X-ray diffraction measurements and Young's modulus has been calculated in the direction of fibre reorientation and compared with the experimental measurements. The results obtained indicate that X-ray diffraction techniques can be used for the study of the mechanical properties of extensible fibrous materials.     

Adaptive digital spectroscopy in programmable logic

High data rate in nuclear spectroscopy can be achieved by using digital shaping techniques. Currently, the use of held-programmable gate arrays as digital processors is hugely increasing, especially in real time applications. In this paper, we deal with the problem of the minimization of the computation burden, in order to allow the use of the least possible hardware, which in turn allows the minimization of power dissipation, size etc., of the processing machine. In order to get at-most advantages of spatial computing in programmable devices, data-path structures of temporal computing process techniques have been revised. Among the improvements consequent to the optimization of architectures, we address three topics: reduction of processing speed, resource saving, and adaptive dynamic management of digital filters length for increasing resolution     

Wind tunnel tests on heavy road vehicles: Cross wind induced loads—Part 2

The sensitivity of heavy road vehicle aerodynamic coefficients to different testing parameters (scenario, vehicle type and turbulence intensity) is experimentally evaluated in this paper through wind tunnel experiments. The first part of the paper has investigated the aerodynamic loads (both stationary and non-stationary) acting on a high-sided lorry (VAN) in a flat ground scenario. The mean aerodynamic coefficients, the flow pattern around the vehicle and the aerodynamic admittance function have been assessed and compared for different wind turbulence conditions (boundary layer simulations). The present paper instead investigates the influence of the infrastructure scenario (flat ground, embankment, single and double viaduct), of the exposition (upwind or downwind) and of a trailed unit on the aerodynamic loads acting on the vehicle. Moreover, the mean aerodynamic coefficients and the aerodynamic admittance function of the high-sided lorry considered in the first part are compared with the ones of other heavy vehicles (tank truck, tractor-semitrailer combination and tractor-trailer combination) to assess the influence of the vehicle geometry.     

1.2V NOR flash memory in system-in-package

A NOR Flash memory system, the supply voltage of which can be as low as 1.2 V, is described. The internal memory chip supply voltage (1.8 V) is obtained by means of a DC-DC converter totally included in the same package of the memory. This system represents a way to overcome technology limitations to generate a Flash device supplied at a voltage close to 1 V and below. The NOR Flash memory system is assembled in a ball grid array 88 balls 14times8times1.6 mm, with the same ballout of the standard Flash memory working at 1.8 V     

Pediatric risk of mortality: an assessment of its performance in a sample of 26 Italian intensive care units

OBJECTIVE: To assess the validity of the Pediatric Risk of Mortality (PRISM) scoring system in accurately predicting the probability of mortality in an Italian intensive care unit (ICU) sample. DESIGN: Prospective, observational, multicenter study. SETTING: Twenty-six Italian ICUs classified into two groups: a) ICUs specifically dedicated to treating pediatric patients; and b) adult ICUs treating children on a regular basis. PATIENTS: Consecutive patients (n = 1,533) <15 yrs of age admitted during 1 yr. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: To assess the performance of the PRISM scoring system, the discrimination and calibration measures were adopted both in the whole population and in 12 preselected subgroups. A good discrimination capability of the scoring system was observed for both the whole population and subgroups (areas under the receiver operating characteristic curves were never <0.82). On the other hand, we documented an unsatisfactory calibration capability in the whole population and in most subgroups (p values of the Hosmer-Lemeshow goodness-of-fit test were <.001 in all but two subgroups). CONCLUSIONS: The analyses suggest that the unsatisfactory calibration of PRISM can be attributed to various reasons. Among those reasons, a poor performance of the system, as well as its sensitivity to factors not connected to clinical ICU performance, seem particularly important. A special caution is needed in adopting a severity of illness scoring system to assess quality of care, particularly in contexts different from the one in which the instrument was originally developed.     

Stereoselective determination of unchanged and glucuroconjugated eliprodil, a new anti-ischaemic drug, in human plasma and urine by precolumn derivatization and column-switching high-performance liquid chromatography with fluorescence detection

An HPLC method was developed and validated for the determination in human plasma and urine of the enantiomers of eliprodil, (+/-)-alpha-(4-chlorophenyl)-4[(4-fluorophenyl) methyl]piperidine-1-ethanol hydrochloride, a new anti-ischaemic agent administered as a racemate. Both enantiomers are present in human plasma in unchanged and glucuroconjugated form, whereas only the glucuroconjugated form is excreted into urine; as a consequence, such metabolites in human plasma and urine should be submitted to enzymatic deconjugation with beta-glucuronidase (Escherichia coli) before being extracted. The general method involves a liquid-liquid extraction of eliprodil and internal standard from alkalinized plasma or urine with n-hexane, evaporation of the organic phase and derivatization with (S)-(+)-naphthylethyl isocyanate to give carbamate diastereoisomeric derivatives of (S)-(+)- and (R)-(-)-eliprodil and internal standard; after evaporation of the derivatizing mixture and dissolution of the residue in a small volume of phosphate buffer-acetonitrile (60:40, v/v), an aliquot is injected into a column-switching HPLC system. The derivatized sample extract is purified on a precolumn filled with C8-bonded silica material, which is flushed with acetonitrile-water, then diastereoisomers of eliprodil and the internal standard are automatically transferred by the mobile phase to the analytical column. The analytical column is a C8 type, specially deactivated for basic compounds, the mobile phase is 0.025 M phosphate buffer (pH 2.6)-methanol-acetonitrile (42:2:56) at a flow-rate of 1.2 ml min-1 and fluorimetric detector operating at lambda ex = 275 nm and lambda em = 336 nm is used. The retention times, under these conditions, are about 16 and 17 min for (S)-(+)- and (R)-(-)-eliprodil diastereoisomers, respectively, and about 19 min for the first-eluted diastereoisomer of the internal standard. During the analysis time, the precolumn, reset in a different path from that of the analytical column, is back-flushed with different solvents, then re-equilibrated with acetonitrile-water before the next injection. Linearity in plasma, for unchanged eliprodil enantiomers, was assessed in the range 0.15-10 ng ml-1 and for total eliprodil enantiomers (unchanged + conjugated) in the range 0.75-500 ng ml-1; the limit of quantitation (LOQ) is 0.15 ng ml-1 for each unchanged enantiomer and 0.75 ng ml-1 for each total enantiomer. Linearity was also assessed in urine for total (conjugated) eliprodil enantiomers in the range 50-25 000 ng ml-1; the LOQ is 50 ng ml-1 for each enantiomer. The intra- and inter-day precision and accuracy of the method were investigated in plasma and urine and found to be satisfactory for pharmacokinetic studies. The method has been extensively used in pharamcokinetic studies in man treated with a 20-mg dose of eliprodil racemate and some results of this application are reported.