Flexural Performance of Concrete Beams Reinforced with FRP Grids

This paper evaluates the flexural performance of simply supported concrete beams subjected to four-point monotonic loading and reinforced with a 2D fiber-reinforced plastic (FRP) grid. The main parameter of the study is the amount of longitudinal FRP reinforcement. With respect to a balanced strain condition, three underreinforced and two overreinforced FRP designs were tested with three identical beams per design. Laboratory recorded load-deflection, failure mode, cracking behavior, and reinforcement strain data are compared with theoretical predictions calculated according to traditional steel-reinforced concrete procedures. The study concludes that, with respect to ACI 318-95, flexural capacity is accurately predicted, but shear strength is not. Deflection compatibility between test results and ACI predictions employing the Branson effective moment of inertia was dependent on the percentage of longitudinal reinforcement. In general, observed flexural stiffness was less than that predicted by Branson's equation. A moment-curvature deflection procedure employing a bilinear concrete model compared very well with measured deflections. Finally, the grid configuration provides an effective force transfer mechanism. Cracking occurred at transverse bar locations only, and FRP tensile rupture was achieved with no observed deterioration in force transfer mechanics.     

MEMS technology integrated in the CMOS back end

The Nanomech? MEMS technology platform which implements arrays of MEMS devices embedded inside the CMOS back end is described. The key advantages of this integration approach are described in terms of achieving a reliable MEMS technology process within competitive cost requirements, without any need for dedicated process, material and packaging development. The choice of materials is also providing a strong and reliable technology for harsh environment applications where cost is also a key. Data is shown providing a broad picture of the Nanomech? technology and its potentials for applications.     

Comparison of rectangular and bisinusoidal waveforms in a miniature planar high-field asymmetric waveform ion mobility spectrometer

High-field asymmetric waveform ion mobility spectrometry (FAIMS) separates ions by utilizing the mobility differences of ions at high and low fields. The shape of the waveform is one of the essential features affecting the resolution, transmission, and separation of FAIMS. Due to practical circuitry advantages, sinusoidal asymmetric waveforms are typically used in FAIMS, whereas theoretical studies indicate that square asymmetric waveforms improve ion separation, resolution, and sensitivity. Results from FAIMS using square and sinusoidal waveforms are presented, and effects of the waveforms on ion separation are discussed. A FAIMS system interfaced with a quadrupole ion trap mass spectrometer was used in this study. FAIMS spectra were generated by scanning the compensation voltage (CV) while operating the mass spectrometer in total ion mode. The identification of ions was accomplished through mass spectra acquired at fixed values of ions' CVs. Square waveform evaluation was done by acquiring data at three frequencies and six duty cycles of the square waveform generator. The performance of FAIMS using square and sinusoidal waveforms at 250, 333, and 500 kHz frequencies was compared, and trends were identified. For all frequencies, the best response of FAIMS was achieved at the lower amplitudes and under the lower duty cycles of the square waveform generator. The separation of FAIMS was better at the higher frequencies. These results demonstrate the potential to incorporate square-wave FAIMS into the design of a miniature device for detection of explosives in the field. SIMION version 8.0, the ion trajectory modeling program, was utilized to optimize the performance of the miniature FAIMS cell and to validate experimental results.     

Clinical implications of clinically insignificant store fragments after extracorporeal shock wave lithotripsy

PURPOSE: We determined the natural history and clinical significance of small, asymptomatic, noninfection related stone fragments after extracorporeal shock wave lithotripsy (ESWL). MATERIALS AND METHODS: We prospectively followed 160 patients with 4 mm. or less asymptomatic calcium oxalate/phosphate stone fragments after ESWL for 1.6 to 88.8 months (mean 23) to stone-free status, censorship or intervention. Kaplan-Meier estimates of probability to anatomical stone-free, decreased or stable status were determined as well as the probability of symptomatic episodes or required urological intervention. RESULTS: Stone-free status or a decreased, stable or increased amount of residual stone occurred in 38 (23.8%), 26 (16.3%), 67 (41.9%) and 29 (18.1%) of the 160 patients, respectively. At 5 years after ESWL the probability of a stone-free, stone-free or decreased status, or stone-free, decreased or stable status was 0.36, 0.53, and 0.80, respectively. A total of 91 patients (56.9%) remained asymptomatic while 69 (43.1%) had a symptomatic episode or required intervention 1.6 to 85.4 months (mean 26) after ESWL (probability estimated at 0.71 at 5 years). CONCLUSIONS: While patients with small noninfection related stone fragments after ESWL may be followed expectantly, a significantly number will require intervention or have symptomatic episodes within 2 years. The term clinically insignificant applied to any residual stone after ESWL is likely a misnomer.     

Enhanced resolution for future fabrication

We have developed resolution-enhanced optical lithography processes that have enabled us to fabricate devices with deep sub-100 nm feature sizes. Isolated gate features were resolved down to 40 nm in resist using optimized phase-shift lithography processes. The addition of a small reactive ion etch (RIE) etch bias allowed us to fabricate transistors with gate lengths in the range 9-25 nm. This was achieved using standard 248 nm optical stepper, photoresist, and RIE technology. The capability is valuable for providing robust fabrication processes for advanced device technology studies. Double-exposure phase-shift imaging is also achieving growing industry acceptance with promising new results recently reported by UMC and Intel. These results show that optical lithography with aggressive resolution enhancements will likely be able to meet the needs of the semiconductor industry for the rest of this decade, pushing out the anticipated introduction of next-generation lithography (NGL) technologies further into the future.     

Solder flow on narrow copper strips

Various solderability tests have been developed over the years to quantify the wetting behavior of solder on metallic surfaces. None offer an exact measure of capillary flow normally associated with conventional plated-through-hole and surface mount soldering. With shrinking package designs, increasing reliability requirements, and the emergence of new soldering technologies, there is a growing need to better understand and predict the flow of solder on printed wiring board (PWB) surfaces. Sandia National Laboratories has developed a capillary flow solderability test, through a joint effort with the National Center for Manufacturing Sciences, that considers this fundamental wetting issue for surface mount technology. The test geometry consists of a metal strip (width, 8) connected to a circular metal pad (radius, r_c). Solder flow from the pad onto the strip depends on the geometric relationship between 8 and r_c. Test methodology, experimental results, and validation of a flow model are presented in this paper.     

X-band fully depleted SOI Amplifier with adaptive bias control

A 10-GHz amplifier with an adaptive bias control circuit is realized using fully depleted SOI CMOS technology. The effective gate bias of the amplifier MOSFET adjusts itself based on the power level of the input signal. Measured results showed reduction of overall power consumption and wider range of output power near its peak efficiency. At absence of the signal, the amplifier can be automatically switched to a standby mode with approximately 85% reduction of power consumption. Power saving is also demonstrated for pulsed signal modulated at 10 MHz.     

The axis-inducing activity, stability, and subcellular distribution of beta-catenin is regulated in Xenopus embryos by glycogen synthase kinase 3

The serine/threonine kinase Xgsk-3 and the intracellular protein beta-catenin are necessary for the establishment of the dorsal-ventral axis in Xenopus. Although genetic evidence from Drosophila indicates that Xgsk-3 is upstream of beta-catenin, direct interactions between these proteins have not been demonstrated. We demonstrate that phosphorylation of beta-catenin in vivo requires an in vitro amino-terminal Xgsk-3 phosphorylation site, which is conserved in the Drosophila protein armadillo. beta-catenin mutants lacking this site are more active in inducing an ectopic axis in Xenopus embryos and are more stable than wild-type beta-catenin in the presence of Xgsk-3 activity, supporting the hypothesis that Xgsk-3 is a negative regulator of beta-catenin that acts through the amino-terminal site. Inhibition of endogenous Xgsk-3 function with a dominant-negative mutant leads to an increase in the steady-state levels of ectopic beta-catenin, indicating that Xgsk-3 functions to destabilize beta-catenin and thus decrease the amount of beta-catenin available for signaling. The levels of endogenous beta-catenin in the nucleus increases in the presence of the dominant-negative Xgsk-3 mutant, suggesting that a role of Xgsk-3 is to regulate the steady-state levels of beta-catenin within specific subcellular compartments. These studies provide a basis for understanding the interaction between Xgsk-3 and beta-catenin in the establishment of the dorsal-ventral axis in early Xenopus embryos.     

Choosing to sever or maintain association induces biased impression formation.

Impression formation should be biased in individuals who decide to maintain or sever association because they desire to form impressions that support their decision. Because such individuals also should wish to appear objective, decision-supporting information should be irrelevant to obvious reasons for the decision ( e.g., a target's social stigma ) . Accepting the veracity of the target's stereotype-irrelevant attributes supports the decision and also can seem objective, although such processing is biased. In 2 experiments, participants were induced to choose or were assigned to maintain or sever association with an alleged fellow participant. Participants who chose to maintain or sever association used biased processes. In the 2nd experiment, the effect of choice on participants' communicated impressions was mediated by biased processes. The relation of this work to dissonance theory and implications for prejudice are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)