Effects of Operating Parameters on the Static Properties ofPulsed Laser Welded Zinc-Coated Steel.

The paper presents an analysis of the influences of the dominant parameters of the pulsed Nd:YAG laser seam welding process on the static behaviour of the welds. These parameters include average peak power density (APPD), mean laser power, traverse speeds, pulse duration, and pulse shapes. Three typical temporal pulse types – ramp-up, ramp-down, and "rectangu-lar" power pulses were used in this study. Laser seam welds were produced in 0.7 mm thick electrogalvanised steel sheets. A number of destructive tests of pulsed Nd:YAG laser welded zinc-coated steel sheet have been carried out to characterise the static properties of welds including hardness, bending strength, and ductility. An experimental study of acceptable welds revealed that the hardness was affected only by the traverse speed. The bend strength was increased with decreas-ing travel speed and increasing pulsed laser parameters. It was found that the operating parameters have no effect on the tensile strengths of the welds.     

The Effect of Nanoparticle Convection-Diffusion Loss on the Transfer Function of an Aerosol Particle Mass Analyzer

The existing theoretical response spectra of APM-3600 agree well with the experimental data for submicron particles larger than 100 nm in the electrical mobility diameter but not for nanoparticles. In this study, a 2-D numerical model was developed to predict the transfer function and response spectra of APM-3600 based on the detailed simulation of flow and particle concentration fields. It was found that recirculation flows existed in the annular classifying region and APM's inlet and outlet regions, which led to enhanced convection-diffusion loss of nanoparticles compared to that without considering flow recirculation. As a result, the APM underestimates the mass of naonoparticles due to the shift of the peak position of the transfer function to a larger diameter than the targeted diameter. The response spectra calculated with the simulated transfer function agree well both in shapes and peak values with the experimental data present in a previous study for both nanoparticles and submicron particles larger than 100 nm. The predicted particle masses also agree well with the PSL's experimental data of the article.

Copyright 2014 American Association for Aerosol Research     

Effective throughput maximization for in-band sensing and transmission in cognitive radio networks

In cognitive radio networks, a secondary user is expected to utilize idle periods in a spectrum band but avoid interfering with busy periods occupied by primary users in the same band. To achieve the above goal, usually a secondary user periodically senses a spectrum band, and once an idle period is detected, the secondary user sends data in a transmission time. Due to (i) miss-detection of busy periods or (ii) unpredictable arrivals of busy periods, a secondary user may send data in busy periods, which causes useless data transmission. A secondary user usually cares about effective throughput which excludes the useless transmitted data. In order to alleviate the useless data transmission and enhance effective throughput, we consider dividing one long data transmission into two or more smaller data transmissions. Analyses, which are verified by simulations, are developed in this paper to calculate effective throughput in a periodic sensing structure with sensing errors. We use the analyses to select a set of parameters of sensing and transmission such that effective throughput is maximized at a certain load while the interference is below a pre-determined level. Besides, we study two policies, namely, fixed parameter policy and dynamic parameter policy, to maximize effective throughput in a spectrum band with variable loads; the former policy selects and applies one fixed set of parameters to different loads, but the latter policy uses different sets of parameters in different loads respectively. Numerical results show that the dynamic parameter policy outperforms the fixed parameter policy.     

Relationships of orbital computed tomographic findings and activity scores to the prognosis of corticosteroid therapy in patients with Graves'' ophthalmopathy

PSD-95/SAP90, which binds to the C-terminus of NMDA receptor and Shaker-type potassium channel, is one of the major postsynaptic density proteins. Recently, novel classes of proteins interacting with the guanylate kinase domain of PSD-95 have been identified, guanylate kinase-associated protein (GKAP) and SAP90/PSD-95-associated proteins (SAPAPs). Here we report the isolation of new isoforms of PSD-95 binding protein (GKAP/SAPAP1) using the yeast two-hybrid system. The isolated protein directly interacts with the guanylate kinase domain of PSD-95. Northern blot analyses revealed that the expression of these isoforms containing distinct N-terminal sequences is differentially regulated during brain development. The present findings suggest that each isoform of the PSD-95 binding protein is differentially expressed in a development-dependent manner and may be involved in the complex formation of PSD-95 and channel/receptors at the postsynaptic density.     

X-Ray Visualized Sensors for Peritoneal Dialysis Catheter Infection

Peritonitis is a common complication for patients with end-stage renal disease undergoing peritoneal dialysis (PD) and is a direct cause or contributor in >15% deaths in PD patients. Since early detection is key to treatment, patients and their care teams need rapid, on-site diagnostics. A hydrogel-based peritoneal fluid pH sensor attached to a peritoneal dialysis catheter is developed to measure local acidosis indicative of peritoneal infections for early detection and monitoring of infections using X-ray imaging. The sensor comprises a polyacrylic acid hydrogel with embedded radiopaque markers enclosed in a polymer casing; contraction of the hydrogel in response to acidic pH is evident from the radiographically measured marker position. The sensor has a pH 4–8 response range; between pH 6.5 and 7.5 it responds linearly with a slope of 14% pH 7 length per pH unit, and about 1% length precision. The sensor is attached to a catheter and implanted in a rat peritoneum. Results in awake rats show a rapid pH drop during infection not observed in systemic C-reactive proteins (CRP) levels nor in the uninfected control animal, with negligible drift over 2 weeks. To our knowledge, this is the first report of an in vivo chemically responsive hydrogel sensor.