FreedomCAR - Aftertreatment Subsystem Development

The primary objective of this program was to develop generic aftertreatment technologies applicable for LDV and LDT engines ranging from 55 kW to 200kW, to develop an optimized and integrated aftertreatment system for a LDT (Light Duty Truck) type vehicle, and to demonstrate the technology which will enable light duty diesel engines to meet Federal Tier II regulation with minimum impact on fuel economy. Specifically, the development targets for emissions reduction and fuel injection penalty are given below: (1) NOx conversion efficiency > 90% (hot), > 84% (combined); (2) PM conversion efficiency > 90% (hot), > 84% (combined); (3) Fuel penalty over FTP-75 Less than 5%; and (4) Fuel penalty at Cruise condition Less than 3%. Development of cost-effective, highly efficient diesel exhaust aftertreatment systems in combination with very low engine out emission combustion development are essential elements for realization of Federal Tier II emission standards for Light Duty Trucks and Vehicles. Evaluation of several aftertreatment technologies was completed as part of this program. A combination of Diesel Oxidation Catalyst, NOx Adsorbing Catalyst and Catalyzed Soot Filter was found to provide the levels of conversion efficiency required to achieve the emission targets. While early systems required relatively large catalyst volumes, external dosing, sulfur traps, full bypass configurations and high levels of Platinum metals; the final system is a compact, scalable, flow-through, fully-integrated and engine-managed aftertreatment system capable of commercial application for Light Duty Vehicles and Trucks. NOx adsorber/particulate filter technology is particularly attractive for Light Duty applications due to the lower exhaust flow and temperature requirements as compared to Heavy Duty engines. Despite these strong positive aspects, NOx Adsorbers are challenged by their regeneration requirements and susceptibility to sulfur poisoning and thermal degradation. Capability was developed to regenerate the NOx Adsorber for NOx and SOx as well as the Particulate Filter for soot. This system was fully integrated into a truck and evaluated over the chassis dynamometer for emissions capability and in real-world winter field testing. Durability of the system was evaluated over a variety of accelerated and real-time dynamometer tests. Excellent NOx and PM conversion efficiency was demonstrated, even following 3000 hrs of endurance testing. Unregulated emissions emitted by the system were evaluated as was the fuel penalty associated with the DeNOx and DeSOx regeneration processes. In the final evaluation, the system demonstrated 90% NOx conversion and 99% PM conversion at a 6% fuel penalty over the FTP-75 test cycle. While target fuel penalty levels were demonstrated using full-bypass configuration systems, the cost associated with those systems was prohibitively high and would preclude successful commercialization of the technology. Although the flow-through configuration fell 1% short of the 5% fuel penalty target, the cost of this configuration is such that commercial application is feasible. Cost drivers for the final system configuration were identified and demonstrate areas where future development areas could focus

Protein folding on the ribosome studied using NMR spectroscopy

NMR spectroscopy is a powerful tool for the investigation of protein folding and misfolding, providing a characterization of molecular structure, dynamics and exchange processes, across a very wide range of timescales and with near atomic resolution. In recent years NMR methods have also been developed to study protein folding as it might occur within the cell, in a de novo manner, by observing the folding of nascent polypeptides in the process of emerging from the ribosome during synthesis. Despite the 2.3 MDa molecular weight of the bacterial 70S ribosome, many nascent polypeptides, and some ribosomal proteins, have sufficient local flexibility that sharp resonances may be observed in solution-state NMR spectra. In providing information on dynamic regions of the structure, NMR spectroscopy is therefore highly complementary to alternative methods such as X-ray crystallography and cryo-electron microscopy, which have successfully characterized the rigid core of the ribosome particle. However, the low working concentrations and limited sample stability associated with ribosome-nascent chain complexes means that such studies still present significant technical challenges to the NMR spectroscopist. This review will discuss the progress that has been made in this area, surveying all NMR studies that have been published to date, and with a particular focus on strategies for improving experimental sensitivity

Validation of the Implementation Climate Scale in Nursing

BackgroundOne critical factor in effective implementation of evidence‐based practices (EBPs) in nursing is an organizational context that facilitates and supports implementation efforts. Measuring implementation climate can add useful insights on the extent to which the organizational context supports EBP implementation.AimsThis study cross‐validates and examines the psychometric properties of the Implementation Climate Scale (ICS), which measures nurses’ perceptions of their unit’s climate for EBP implementation.MethodsThis study analyzed ICS data from two cross‐sectional studies, including 203 nurses from California and 301 nurses from Florida. Analyses included evaluation of internal consistency, multilevel aggregation statistics, and confirmatory factor analyses.ResultsThe 18‐item ICS demonstrated comparable psychometric properties to the original measure development paper in both samples. Confirmatory factor analyses provided support for the scale’s factor structure in both samples.Linking Evidence to PracticeThe ICS is a pragmatic measure that can be used to assess unit implementation climate in nursing contexts. Results from the ICS from nurses and nurse leaders can provide insights into implementation‐specific barriers and facilitators within the organizational context.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/167548/1/wvn12500_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/167548/2/wvn12500.pd

Neighborhood-level and individual-level correlates of cannabis use among young persons living with HIV/AIDS

INTRODUCTION: In addition to individual characteristics, there may be a wide range of environmental or neighborhood stressors that contribute to elevated cannabis use in groups of youth living with HIV/AIDS (YLHIV); however, the effects of social disorganization on cannabis use in YLHIV to date have not been studied. METHODS: We examined the effects of individual-level and neighborhood-level factors by developing hierarchical generalized linear models estimating odds of current cannabis use (any use during the past 3 months) and daily cannabis use among a sample of YLHIV (N=1921) currently receiving medical care. RESULTS: The final model for daily cannabis use in the past 3 months included significant positive effects associated with hostility (O.R.=1.08, 95% C.I.: 1.05, 1.11), being older (O.R.= 1.12, 95% C.I.: 1.05, 1.20), being a bisexual male (O.R.=1.72, 95% C.I.: 1.10, 2.70), and residing in a community with a murder rate in the highest quartile (O.R.= 1.91, 95% C.I.: 1.27, 2.87), second highest quartile (O.R.=1.62, 95% C.I.: 1.06, 2.46), or third highest quartile (O.R.=1.52, 95% C.I.: 1.01, 2.30). DISCUSSION: This paper advances our knowledge of the multilevel factors associated with elevated cannabis use among groups of YLHIV and furthers our understanding of social and structural determinants of health in this population. Future research into cannabis use among YLHIV should consider, not only cannabis use within the context of the adjustment of living with HIV/AIDS, but also the stressors that characterize the environments in which groups of YLHIV live