Impact of lubricant composition on low-speed pre-ignition

One of the limits on the maximum fuel efficiency benefit to be gained from turbocharged, downsized gasoline engines is the occurrence of pre-ignitions at low engine speed. These pre-ignitions may lead to high pressures and extreme knock (megaknock or superknock) which can cause severe engine damage. Though the mechanism leading to megaknock is not completely resolved, pre-ignitions are thought to arise from local autoignition of areas in the cylinder which are rich in low ignition delay "contaminants" such as engine oil and/or heavy ends of gasoline. These contaminants are introduced to the combustion chamber at various points in the engine cycle (e.g. entering from the top land crevice during blow-down or washed from the cylinder walls during DI wall impingement). This paper presents results from tests in which model "contaminants", consisting of engine lubricant base stocks, base stocks mixed with fuel and base stocks mixed with one or more additives were injected directly into a test engine to determine their propensity to ignite. The ignition tendency was found to be lower for less reactive base stocks and for base stocks mixed with certain additives. Further, when small amounts of fuel were mixed with relatively non-ignitive lubricant base stocks the ignition tendency was found to increase significantly. These results may guide development of new lubricants which could be used to reduce megaknock in downsized engines. Copyright © 2014 SAE International.

In-Situ Boron and Aluminum Doping and Their Memory Effects in 4H-SiC Homoepitaxial Layers Grown by Hot-Wall LPCVD

The in-situ p-type doping of 4H-SiC grown on off-oriented (0001) 4H-SiC substrates was performed with trimethylaluminum (TMA) and/or diborane (B2H6) as the dopants. The incorporations of Al and B atoms and their memory effects and the electrical properties of p-type 4H-SiC epilayers were characterized by secondary ion mass spectroscopy (SIMS) and Hall effect measurements, respectively. Both Al- and B-doped 4H-SiC epilayers were p-type conduction. It was shown that the profiles of the incorporated boron and aluminum concentration were in agreement with the designed TMA and B2H6 flow rate diagrams. The maximum hole concentration for the Al doped 4H-SiC was 3.52x10(20) cm(-3) with Hall mobility of about 1 cm(2)/Vs and resistivity of 1.6 similar to 2.2x10(-2) Omega cm. The heavily boron-doped 4H-SiC samples were also obtained with B2H6 gas flow rate of 5 sccm, yielding values of 0.328 Omega cm for resistivity, 5.3x10(18) cm(-3) for hole carrier concentration, and 7 cm(2)/VS for hole mobility. The doping efficiency of Al in SiC is larger than that of B. The memory effects of Al and B were investigated in undoped 4H-SiC by using SIMS measurement after a few run of doped 4H-SiC growth. It was clearly shown that the memory effect of Al is stronger than that of B. It is suggested that p-type 4H-SiC growth should be carried out in a separate reactor, especially for Al doping, in order to avoid the join contamination on the subsequent n-type growth. 4H-SiC PiN diodes were fabricated by using heavily B doped epilayers. Preliminary results of PiN diodes with blocking voltage of 300 V and forward voltage drop of 3.0 V were obtained.

Determinants of left ventricular mass as measured by Doppler echocardiography in pre-adolescents

This study examined factors contributing to the differences in left ventricular mass as measured by Doppler echocardiography in children. Fourteen boys (10.3 ± 0.3 years of age) and 1 1 girls (10.5 ± 0.4 years of age) participated in the study. Height and weight were measured, and relative body fat was determined from the measurement of skinfold thickness according to Slaughter et al. (1988). Lean Body Mass was then calculated by subtracting the fat mass from the total body mass. Sexual maturation was self-assessed using the stages of sexual maturation by Tanner (1962). Both pubic hair development and genital (penis or breast for boys and girls respectively) development were used to determine sexual maturation. Carotid Pulse pressure was assessed by applanation tomometry in the left carotid artery. Cardiac mass was measured by Doppler Echocardiography. Images of cardiac structures were taken using B-Mode and were then translated to M- Mode. The dimensions at the end diastole were obtained at the onset of the QRS complex of the electrocardiogram in a plane through a standard position. Measurements included: (a) the diameter of the left ventricle at the end diastole was measured from the septum edge to the endocardium mean border, (b) the posterior wall was measured as the distance from to anterior wall to the epicardium surface, and (c) the interventricular septum was quantified as the distance from the surface of the left ventricle border to the right ventricle septum surface. Systolic time measurements were taken at the peak of the T-wave of the electrocardiogram. Each measurement was taken three to five times before averaging. Average values were used to calculate cardiac mass using the following equation (Deveraux et al. 1986). Weekly physical activity metabolic equivalent was calculated using a standardize activity questionnaire (Godin and Shepard, 1985) and peakV02 was measured on a cycloergometer. There were no significant differences in cardiovascular mesurements between boys and girls. Left ventricular mass was correlated (p<0.05) with size, maturation, peakV02 and physical activity metabolic equivalent. In boys, lean body mass alone explained 36% of the variance in left ventricular mass while weight was the single strongest predictor of left ventricular mass (R =0.80) in girls. Lean body mass, genital developemnt and physical activity metabolic equivalent together explained 46% and 81% in boys and girls, respectively. However, the combination of lean body mass, genital development and peakV02 (ml kgLBM^ min"') explained up to 84% of the variance in left ventricular mass in girls, but added nothing in boys. It is concluded that left ventricular mass was not statistically different between pre-adolescent boys and girls suggesting that hormonal, and therefore, body size changes in adolescence have a main effect on cardiac development and its final outcome. Although body size parameters were the strongest correlates of left ventricular mass in this pre-adolescent group of children, to our knowledge, this is the first study to report that sexual maturation, as well as physical activity and fitness, are also strong associated with left ventricular mass in pre-adolescents, especially young females. Arterial variables, such as systolic blood pressure and carotid pulse pressure, are not strong determinants of left ventricular mass in this pre-adolescent group. In general, these data suggest that although there is no gender differences in the absolute values of left ventricular mass, as children grow, the factors that determine cardiac mass differ between the genders, even in the same pre-adolescent age.

Modification of cell wall properties in lettuce improves shelf life

It is proposed that post-harvest longevity and appearance of salad crops is closely linked to pre-harvest leaf morphology (cell and leaf size) and biophysical structure (leaf strength). Transgenic lettuce plants (Lactuca sativa cv. Valeria) were produced in which the production of the cell wall-modifying enzyme xyloglucan endotransglucosylase/hydrolase (XTH) was down-regulated by antisense inhibition. Independently transformed lines were shown to have multiple members of the LsXTH gene family down-regulated in mature leaves of 6-week-old plants and during the course of shelf life. Consequently, xyloglucan endotransglucosylase (XET) enzyme activity and action were down-regulated in the cell walls of these leaves and it was established that leaf area and fresh weight were decreased while leaf strength was increased in the transgenic lines. Membrane permeability was reduced towards the end of shelf life in the transgenic lines relative to the controls and bacteria were evident inside the leaves of control plants only. Most importantly, an extended shelf-life of transgenic lines was observed relative to the non-transgenic control plants. These data illustrate the potential for engineering cell wall traits for improving quality and longevity of salad crops using either genetic modification directly, or by using markers associated with XTH genes to inform a commercial breeding programme.

Comparison of the analytical performance of electrophoresis microchannels fabricated in PDMS, glass, and polyester-toner

This paper compares the analytical performance of microchannels fabricated in PDMS, glass, and polyester-toner for electrophoretic separations. Glass and PDMS chips were fabricated using well-established photolithographic and replica-molding procedures, respectively. PDMS channels were sealed against three different types of materials: native PDMS, plasma-oxidized PDMS, and glass. Polyester-toner chips were micromachined by a direct-printing process using an office laser printer. All microchannels were fabricated with similar dimensions according to the limitations of the direct-printing process (width/depth 150 mu m/12 mu m). LIF was employed for detection to rule out any losses in separation efficiency due to the detector configuration. Two fluorescent dyes, coumarin and fluorescein, were used as model analytes. Devices were evaluated for the following parameters related to electrophoretic separations: EOF, heat dissipation, injection reproducibility, separation efficiency, and adsorption to channel wall.

Mixed-signal analog-digital circuits design on the pre-diffused digital array using trapezoidal association of transistors

The mixed-signal and analog design on a pre-diffused array is a challenging task, given that the digital array is a linear matrix arrangement of minimum-length transistors. To surmount this drawback a specific discipline for designing analog circuits over such array is required. An important novel technique proposed is the use of TAT (Trapezoidal Associations of Transistors) composite transistors on the semi-custom Sea-Of-Transistors (SOT) array. The analysis and advantages of TAT arrangement are extensively analyzed and demonstrated, with simulation and measurement comparisons to equivalent single transistors. Basic analog cells were also designed as well in full-custom and TAT versions in 1.0mm and 0.5mm digital CMOS technologies. Most of the circuits were prototyped in full-custom and TAT-based on pre-diffused SOT arrays. An innovative demonstration of the TAT technique is shown with the design and implementation of a mixed-signal analog system, i. e., a fully differential 2nd order Sigma-Delta Analog-to-Digital (A/D) modulator, fabricated in both full-custom and SOT array methodologies in 0.5mm CMOS technology from MOSIS foundry. Three test-chips were designed and fabricated in 0.5mm. Two of them are IC chips containing the full-custom and SOT array versions of a 2nd-Order Sigma-Delta A/D modulator. The third IC contains a transistors-structure (TAT and single) and analog cells placed side-by-side, block components (Comparator and Folded-cascode OTA) of the Sigma-Delta modulator.

Thermogravimetric studies of decomposition kinetics of six different IAC Hevea rubber clones using Flynn-Wall-Ozawa approach

The thermal degradation behaviour of rubber from six new Hevea brasiliensis clones (IAC 40, 56, 300, 301, 302 and 303) from São Paulo State, Brazil was studied by thermogravimetry using the Flynn-Wall-Ozawa approach to assess the kinetic parameters ( reaction order, activation energy and pre-exponential factor) of the decomposition process. This study indicated that the thermal behaviour is a complex multiple step process, which depends on the type of rubber Hevea clones studied. The rubber from these clones can be classified, following the order of decreasing thermal stability, as IAC 303 > 302 > 56 > 40 > 300 > 301.

Domain wall contribution to dielectric and piezoelectric responses in 0.65Pb(Mg1/3Nb2/3)-0.35PbTiO(3) ferroelectric ceramics

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Periapical radiographs overestimate root canal wall thickness during post space preparation

Aim To evaluate differences between anatomic and radiographic measurements of root canal wall thickness (RCWT) after each root canal preparation stage during post placement.Methodology Twenty mandibular premolars with a single canal were decoronated and the roots embedded in resin using a teflon muffle. Roots were sectioned horizontally at a pre-established level and canals were prepared for post placement. Endodontic hand files were used for root canal preparation, followed by Gates Glidden drills and Peeso reamers. Standardized radiographs and photographs at pre-established measurement levels were taken before preparation, after root canal instrumentation, after Gates Glidden preparation and after Peeso enlargement. All images were digitized and RCWT at the mesial and distal walls measured (IMAGETOOL 3.0). Differences between radiographic and anatomic measurements were analysed with paired t-tests. ANOVA was used to compare the percentages of radiographic distortions.Results Regardless of the time-point evaluated, RCWT determined by radiographs were greater than the respective anatomic measurements (P < 0.05). The difference detected at each stage was similar and constant (P > 0.05).Conclusions Throughout preparation for post placement, radiographic images overestimated the RCWT by approximately 25%, regardless of the clinical stage evaluated.

Cell wall fractions from Paracoccidioides brasiliensis induce hypergammaglobulinemia

The antibody response against the antigen sheep red blood cells (SRBC) was investigated in mice pre-treated with formalin-killed Paracoccidioides brasiliensis or with cell wall fractions of the fungus. Pre-treatment with P. brasiliensis, as well as with the F1 fraction and beta-glucan significantly increased the anti-SRBC antibody response in the experimental groups as compared to the control group that received only SRBC. This immunomodulatory effect varied with the different doses employed and with pre-treatment time. We conclude that the cell wall fractions of P. brasiliensis might play an important role in the hypergammaglobulinemia associated with Paracoccidioidomycosis. © 1993 Kluwer Academic Publishers.

Comparative analysis of three rotary instruments used for coronal pre-enlargement in radicular dentin thickness and root canal area of mandibular molars

Purpose: The purpose of this study was to evaluate the increase of the cervical area and dentin thickness in mesial and distal walls of the mesial canals from mandibular molars after the use of LA Axxess (LA), CP Drill (CP) and Gates-Glidden (GG) rotary instruments. Material and Methods: Sixty root canals from thirty mandibular first molar were sectioned 3 mm below the cement-enamel junction, divided in 3 groups (n = 20 root canals, each) according to rotary instrument used, and the cervical images were captured before and after pre-enlargement instrumentation. The increase of the instrumented cervical area (mm2) and the dentin removal thickness (mm), at mesial and distal walls were calculated using Image tools software, by comparison of images. Data were analyzed by ANOVA and Tukey tests (p=0.05). Results: All rotary instruments promoted thickness reduction in dentin walls. In mesial wall, all rotary instruments promoted similar thickness reduction of dentinal wall and did not differ from each other (p>0.05). In distal wall, LA Axxess instrument promoted higher dentin thickness reduction than other groups (p<0.05). The three rotary instruments promoted different increase at the instrumented cervical area (p<0.05), LA promoted the highest increase area and GG and CP presented similar results. Conclusion: LA 20/0.06 promoted the highest thickness reduction in distal wall and increase of cervical area of root canal. On the other hand, CP was the safest instrument, with lower dentin removal of distal wall and similar increased area to GG.

Saccharomyces cerevisiae: a novel and efficient biological control agent for Colletotrichum acutatum during pre-harvest

In this study, we evaluated the efficiency of six isolates of Saccharomyces cerevisiae in controlling Colletotrichum acutatum, the causal agent of postbloom fruit drop that occur in pre-harvest citrus. We analyzed the mechanisms of action involved in biological control such as: production of antifungal compounds, nutrient competition, detection of killer activity, and production of hydrolytic enzymes of the isolates of S. cerevisiae on C. acutatum and their efficiency in controlling postbloom fruit drop on detached citrus flowers. Our results showed that all six S. cerevisiae isolates produced antifungal compounds, competed for nutrients, inhibited pathogen germination, and produced killer activity and hydrolytic enzymes when in contact with the fungus wall. The isolates were able to control the disease when detached flowers were artificially inoculated, both preventively and curatively. In this work we identified a novel potential biological control agent for C acutatum during pre-harvest. This is the first report of yeast efficiency for the biocontrol of postbloom fruit drop, which represents an important contribution to the field of biocontrol of diseases affecting citrus populations worldwide. (C) 2015 Elsevier GmbH. All rights reserved.

New aspects of airway mechanics in pre-term infants

High-frequency respiratory impedance data measured noninvasively by the high-speed interrupter technique (HIT), particularly the first antiresonance frequency (f(ar,1)), is related to airway wall mechanics. The aim of this study was to evaluate the feasibility and repeatability of HIT in unsedated pre-term infants, and to compare values of f(ar,1) from 18 pre-term (post-conceptional age 32-37 weeks, weight 1,730-2,910 g) and 18 full-term infants (42-47 weeks, 3,920-5,340 g). Among the pre-term infants, there was good short-term repeatability of f(ar,1) within a single sleep epoch (mean (sd) coefficient of variance: 8 (1.7)%), but 95% limits of agreement for repeated measures of f(ar,1) after 3-8 h were relatively wide (-41 Hz; 37 Hz). f(ar,1) was significantly lower in pre-term infants (199 versus 257 Hz), indicating that wave propagation characteristics in pre-term airways are different from those of full-term infants. The present authors suggest that this is consistent with developmental differences in airway wall structure and compliance, including the influence of the surrounding tissue. Since flow limitation is determined by wave propagation velocity and airway cross-sectional area, it was hypothesised that the physical ability of the airways to carry large flows is fundamentally different in pre-term than in full-term infants.

Effects of a latency period between pre-stimulation and teat cup attachment and periodic vacuum reduction on milking characteristics and teat condition in dairy cows

The goal of the present study was to examine the suitability of a short pre-stimulation (P) for 15 s followed by a latency period (L) of 30 s before cluster attachment for machine milking. In addition we tested the effect of a periodic reduction of the vacuum under the teat (VR) during the massage phase from 43 kPa to 12-15 kPa on milking characteristics and teat tissue condition. The study was carried out in 9 cows in a cross-over design. Animals were milked twice daily, and each of the 4 treatment combinations was used for six subsequent milkings (P+L vs. continuous P, and standard pulsation vs. VR, respectively). Milk flow was recorded during all experimental milkings. Longitudinal ultrasound cross sections of the teat were performed by B-mode ultrasound after the last milking of each treatment at 0, 5, and 15 min after the end of milking, respectively. None of the evaluated milking characteristics (total milk yield, main milking time, peak flow rate, average milk flow) differed between treatments. Teat measures as obtained by ultrasound cross sections showed no significant difference if individual treatments were compared at the three time points individually. However, teat wall thickness (TWT) tended to be smaller in VR vs. non-VR treatments at 5 min after milking (P=0·05). In conclusion, teat preparation consisting of a short stimulation followed by a latency period represents a similarly efficient pre-stimulation as a continuous pre-stimulation. VR seems to reduce the load on the teat tissue during milking and thus reduces the development of oedema and hence a less pronounced increase of TWT while milking characteristics are similar with or without VR.

Results of the JET real-time disruption predictor in the ITER-like wall campaigns

The impact of disruptions in JET became even more important with the replacement of the previous Carbon Fiber Composite (CFC) wall with a more fragile full metal ITER-like wall (ILW). The development of robust disruption mitigation systems is crucial for JET (and also for ITER). Moreover, a reliable real-time (RT) disruption predictor is a pre-requisite to any mitigation method. The Advance Predictor Of DISruptions (APODIS) has been installed in the JET Real-Time Data Network (RTDN) for the RT recognition of disruptions. The predictor operates with the new ILW but it has been trained only with discharges belonging to campaigns with the CFC wall. 7 realtime signals are used to characterize the plasma status (disruptive or non-disruptive) at regular intervals of 1 ms. After the first 3 JET ILW campaigns (991 discharges), the success rate of the predictor is 98.36% (alarms are triggered in average 426 ms before the disruptions). The false alarm and missed alarm rates are 0.92% and 1.64%.