Chemical Kinetic Models for HCCI and Diesel Combustion

Predictive engine simulation models are needed to make rapid progress towards DOE's goals of increasing combustion engine efficiency and reducing pollutant emissions. These engine simulation models require chemical kinetic submodels to allow the prediction of the effect of fuel composition on engine performance and emissions. Chemical kinetic models for conventional and next-generation transportation fuels need to be developed so that engine simulation tools can predict fuel effects. The objectives are to: (1) Develop detailed chemical kinetic models for fuel components used in surrogate fuels for diesel and HCCI engines; (2) Develop surrogate fuel models to represent real fuels and model low temperature combustion strategies in HCCI and diesel engines that lead to low emissions and high efficiency; and (3) Characterize the role of fuel composition on low temperature combustion modes of advanced combustion engines

Fluoroquinolone Efficacy against Tuberculosis Is Driven by Penetration into Lesions and Activity against Resident Bacterial Populations.

Fluoroquinolones represent the pillar of multidrug-resistant tuberculosis (MDR-TB) treatment, with moxifloxacin, levofloxacin, or gatifloxacin being prescribed to MDR-TB patients. Recently, several clinical trials of "universal" drug regimens, aiming to treat drug-susceptible and drug-resistant TB, have included a fluoroquinolone. In the absence of clinical data comparing their side-by-side efficacies in controlled MDR-TB trials, a pharmacological rationale is needed to guide the selection of the most efficacious fluoroquinolone. The present studies were designed to test the hypothesis that fluoroquinolone concentrations (pharmacokinetics) and activity (pharmacodynamics) at the site of infection are better predictors of efficacy than the plasma concentrations and potency measured in standard growth inhibition assays and are better suited to determinations of whether one of the fluoroquinolones outperforms the others in rabbits with active TB. We first measured the penetration of these fluoroquinolones in lung lesion compartments, and their potency against bacterial populations that reside in each compartment, to compute lesion-centric pharmacokinetic-pharmacodynamic (PK/PD) parameters. PK modeling methods were used to quantify drug penetration from plasma to tissues at human-equivalent doses. On the basis of these metrics, moxifloxacin emerged with a clear advantage, whereas plasma-based PK/PD favored levofloxacin (the ranges of the plasma AUC/MIC ratio [i.e., the area under the concentration-time curve over 24 h in the steady state divided by the MIC] are 46 to 86 for moxifloxacin and 74 to 258 for levofloxacin). A comparative efficacy trial in the rabbit model of active TB demonstrated the superiority of moxifloxacin in reducing bacterial burden at the lesion level and in sterilizing cellular and necrotic lesions. Collectively, these results show that PK/PD data obtained at the site of infection represent an adequate predictor of drug efficacy against TB and constitute the baseline required to explore synergies, antagonism, and drug-drug interactions in fluoroquinolone-containing regimens

Adsorption of 2,2 '-dithiodipyridine as a tool for the assembly of silver nanoparticles

Silver nanostructured thin films stabilized by 2,2’-dithiodipyridine (2dtpy) were prepared. The Ag nanoparticles were obtained by treating the complex [Ag(2dtpy)]NO3 with NaBH4 in a methanol–toluene mixture. The films were transferred to borosilicate glass slips by a dip-coating method and were found to consist of Ag nanoparticles possibly linked via 2dtpy molecules. Surface-enhanced Raman scattering (SERS) studies have offered the possibility of investigating the adsorption modes of 2dtpy at the Ag nanoparticle surfaces in the fil

Variabilidad de rindes de trigo y fertilización nitrogenada

p.115-122En la primera parte del trabajo se presenta un modelo teórico de respuesta del cultivo de trigo a una serie de factores de producción. El objetivo del mismo es permitir la estimación del valor esperado de rinde, E (Y), y la varianza de rinde, V (Y), para cualquier nivel de uso de insumo. En la segunda parte se usa el modelo anterior para analizar el proceso de respuesta del cultivo de trigo al uso de fertilizante nitrogenado. Se utilizan datos experimentales correspondientes a la zona triguera II. Una función polinomial es ajustada a datos de ensayos llevados a cabo en la zona II Norte y en la zona II Sur. Una prueba estadística para detectar la presencia de heterocedasticidad (el Test de Park) permite estimar la influencia del nivel de fertilización nitrogenada sobre la variabilidad de rindes. Se concluye que (1) las dosis óptimas son considerablemente (30-50 por ciento) mayores en la zona II surque en la II Norte, (2) las diferencias (entre zonas) de dosis óptima son mayores cuanto menores son las relaciones de precio fertilizante-trigo y (3) la utilización de fertilizante nitrogenado no parece aumentad el riesgo económico de producción

Efficient alkane oxidation under combustion engine and atmospheric conditions

Efficient autoxidation of organic compounds typically requires that they possess double bonds or oxygen-containing moieties, which is why alkanes were thought to contribute little to atmospheric organic aerosol formation. Here, mass spectrometry shows significant autoxidation of alkanes under both atmospheric and combustion conditions. Oxidation chemistry controls both combustion processes and the atmospheric transformation of volatile emissions. In combustion engines, radical species undergo isomerization reactions that allow fast addition of O-2. This chain reaction, termed autoxidation, is enabled by high engine temperatures, but has recently been also identified as an important source for highly oxygenated species in the atmosphere, forming organic aerosol. Conventional knowledge suggests that atmospheric autoxidation requires suitable structural features, like double bonds or oxygen-containing moieties, in the precursors. With neither of these functionalities, alkanes, the primary fuel type in combustion engines and an important class of urban trace gases, are thought to have minor susceptibility to extensive autoxidation. Here, utilizing state-of-the-art mass spectrometry, measuring both radicals and oxidation products, we show that alkanes undergo autoxidation much more efficiently than previously thought, both under atmospheric and combustion conditions. Even at high concentrations of NOX, which typically rapidly terminates autoxidation in urban areas, the studied C-6-C-10 alkanes produce considerable amounts of highly oxygenated products that can contribute to urban organic aerosol. The results of this inter-disciplinary effort provide crucial information on oxidation processes in both combustion engines and the atmosphere, with direct implications for engine efficiency and urban air quality.Peer reviewe

Efficient alkane oxidation under combustion engine and atmospheric conditions

Oxidation chemistry controls both combustion processes and the atmospheric transformation of volatile emissions. In combustion engines, radical species undergo isomerization reactions that allow fast addition of O2. This chain reaction, termed autoxidation, is enabled by high engine temperatures, but has recently been also identified as an important source for highly oxygenated species in the atmosphere, forming organic aerosol. Conventional knowledge suggests that atmospheric autoxidation requires suitable structural features, like double bonds or oxygen-containing moieties, in the precursors. With neither of these functionalities, alkanes, the primary fuel type in combustion engines and an important class of urban trace gases, are thought to have minor susceptibility to extensive autoxidation. Here, utilizing state-of-the-art mass spectrometry, measuring both radicals and oxidation products, we show that alkanes undergo autoxidation much more efficiently than previously thought, both under atmospheric and combustion conditions. Even at high concentrations of NOX, which typically rapidly terminates autoxidation in urban areas, the studied C6–C10 alkanes produce considerable amounts of highly oxygenated products that can contribute to urban organic aerosol. The results of this inter-disciplinary effort provide crucial information on oxidation processes in both combustion engines and the atmosphere, with direct implications for engine efficiency and urban air quality

Staff training to improve participant recruitment into surgical randomised controlled trials : A feasibility study within a trial (SWAT) across four host trials simultaneously

The PROMoting THE Use of SWATs (PROMETHEUS) programme was funded by the Medical Research Council (MRC) [grant number MR/R013748/1]. The DISC host trial is funded by the Health Technology Assessment Programme (Grant Ref: 15/102/04). IntAct is funded by the Efficacy and Mechanism Evaluation (EME) Programme, an MRC and NIHR partnership (Grant Ref: 14/150/62). The EME Programme is funded by the MRC and NIHR, with contributions from the CSO in Scotland and Health and Care Research Wales and the HSC R&D Division, Public Health Agency in Northern Ireland. PROFHER-2 is funded by the Health Technology Assessment Programme (Grant Ref: 16/73/03). START: REACTS is funded by the NIHR Evaluation, Trials and Studies Co-ordinating Centre (NETSCC); Grant Codes: 16/61/18. The development of the training intervention was funded by the MRC Network of Hubs for Trials Methodology Research (MR/L004933/1- R53) and supported by the MRC ConDuCT-II Hub (Collaboration and innovation for Difficult and Complex randomized controlled Trials In Invasive procedures - MR/K025643/1). The online version of the training intervention was funded by the NIHR and is hosted on the NIHR Learn platform (https://learn.nihr.ac.uk/course/view.php?id=385). It is based on the face-to face GRANULE training course funded by the Bowel Disease Research Foundation in collaboration with the University of Birmingham, University of Bristol and former MRC ConDuCT-II Hub. This work was part-funded by the Wellcome Trust [ref: 204829] through the Centre for Future Health (CFH) at the University of York. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR, the MRC or the Department of Health and Social Care. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the article.Peer reviewedPublisher PD