Characteristics of Resistive PM Sensors for Onboard Diagnostics of Diesel Particulate Filter Failure.

In accordance with the recently reinforced exhaust regulations and onboard diagnostics regulations, it is essential to adopt diesel particulate filter systems in diesel vehicles; a sensor that directly measures particulate matter (PM) in exhaust gas is installed to precisely monitor diesel particulate filter (DPF) failure. Because the reduction of particulate matter in the diesel particulate filter system is greatly influenced by the physical wall structure of the substrate, the presence or absence of damage to the substrate wall (cracks or local melting, etc.) determines the reliability of normal DPF operation. Therefore, an onboard diagnostics sensor for particle matter is being developed with a focus on monitoring damage to the DPF wall. In this study, as a sensor for determining damage to the substrate wall, an accumulation-type sensor whose resistance changes as soot particles are deposited between two electrodes was fabricated. The sensor characteristics were investigated by changing the gap between the sensor electrodes, sensor cap shape, and electrode bias voltage to improve resistive soot sensor sensitivity and response. From the signal characteristics of various sensor configurations, a combination sensor with improved signal stability and response time is manufactured, and they were compared with the characteristics of commercially available sensors in the engine-simulated NEDC mode in terms of the degree of DPF crack. As a result of transient mode, PM monitoring cycle was improved by 1.2~1.5 times during the same vehicle driving time compared to the existing commercial sensor.

Influence of transmucosal designs of three one-piece implant systems on early tissue responses: a histometric study in beagle dogs.

PURPOSE: The purpose of this study was to investigate the early tissue response around three one-piece implant systems with different transmucosal designs. MATERIALS AND METHODS: Three one-piece dental implant systems with different profiles and surface roughnesses on the transmucosal portion were examined in the current study. The transmucosal portions were flared and machined (FM), concave and machined with microgrooves (CMG), or straight and anodic oxidized (SA). A total of 30 implants (10 of each type) were placed in computer-generated randomized order in the mandibular residual ridges of five beagle dogs. Six months later, all animals were sacrificed and histologic sections were prepared to measure epithelial tissue height, connective tissue contact, and the amount of bone resorption. One-way analysis of variance and the Bonferroni post hoc test were used for statistical evaluation (alpha = 95%). RESULTS: After a 6-month nonfunctional loading period, all 30 implants were clinically immobile. Slight swelling and redness of the peri-implant soft tissue were noticed around most of the implant abutments. Histometric analysis showed that the FM implants had a longer epithelial tissue height than the CMG implants. The CMG implants showed the greatest amount of connective tissue attachment among the three groups and the least amount of marginal bone resorption. The CMG and SA implants showed bone growth above the initial reference point at 10 and 7 measurement sites, respectively, whereas no bone overgrowth was noted around the FM implants. CONCLUSION: Based on this study conducted in five beagle dogs, a concave transmucosal profile with a microgrooved surface was associated with longer connective tissue attachments and less bone resorption versus implants that were flared with a machined surface or straight with an anodic oxidized surface in the early healing phase. Int J Oral Maxillofac Implants 2010;25:309-314.