897 research outputs found
Tailoring ZSM-5 Zeolites for the Fast Pyrolysis of Biomass to Aromatic Hydrocarbons
The production of aromatic hydrocarbons from cellulose by zeolite-catalyzed fast pyrolysis involves a complex reaction network sensitive to the zeolite structure, crystallinity, elemental composition, porosity, and acidity. The interplay of these parameters under the reaction conditions represents a major roadblock that has hampered significant improvement in catalyst design for over a decade. Here, we studied commercial and laboratory-synthesized ZSM-5 zeolites and combined data from 10 complementary characterization techniques in an attempt to identify parameters common to high-performance catalysts. Crystallinity and framework aluminum site accessibility were found to be critical to achieve high aromatic yields. These findings enabled us to synthesize a ZSM-5 catalyst with enhanced activity, which offers the highest aromatic hydrocarbon yield reported to date.This is the peer-reviewed version of the following article: Hoff, Thomas C., David W. Gardner, Rajeeva Thilakaratne, Kaige Wang, Thomas W. Hansen, Robert C. Brown, and Jean‐Philippe Tessonnier. "Tailoring ZSM‐5 Zeolites for the Fast Pyrolysis of Biomass to Aromatic Hydrocarbons." ChemSusChem 9, no. 12 (2016): 1473-1482., which has been published in final form at DOI: 10.1002/cssc.201600186. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.</p
Axial Concentration Profiles and NO Flue Gas in a Pilot-Scale Bubbling Fluidized Bed Coal Combustor
Atmospheric bubbling fluidized bed coal combustion of a bituminous coal and anthracite with
particle diameters in the range 500-4000 ím was investigated in a pilot-plant facility. The
experiments were conducted at steady-state conditions using three excess air levels (10, 25, and
50%) and bed temperatures in the 750-900 °C range. Combustion air was staged, with primary
air accounting for 100, 80, and 60% of total combustion air. For both types of coal, high NO
concentrations were found inside the bed. In general, the NO concentration decreased monotonically
along the freeboard and toward the exit flue; however, during combustion with high air
staging and low to moderate excess air, a significant additional NO formation occurred near the
secondary air injection point. The results show that the bed temperature increase does not affect
the NO flue gas concentration significantly. There is a positive correlation between excess air
and the NO flue gas concentration. The air staging operation is very effective in lowering the
NO flue gas, but there is a limit for the first stage stoichiometry below which the NO flue gas
starts rising again. This effect could be related with the coal rank
Gene Expression Analysis Reveals New Possible Mechanisms of Vancomycin-Induced Nephrotoxicity and Identifies Gene Markers Candidates
Vancomycin, one of few effective treatments against methicillin-resistant Staphylococcus aureus, is nephrotoxic. The goals of this study were to (1) gain insights into molecular mechanisms of nephrotoxicity at the genomic level, (2) evaluate gene markers of vancomycin-induced kidney injury, and (3) compare gene expression responses after iv and ip administration. Groups of six female BALB/c mice were treated with seven daily iv or ip doses of vancomycin (50, 200, and 400 mg/kg) or saline, and sacrificed on day 8. Clinical chemistry and histopathology demonstrated kidney injury at 400 mg/kg only. Hierarchical clustering analysis revealed that kidney gene expression profiles of all mice treated at 400 mg/kg clustered with those of mice administered 200 mg/kg iv. Transcriptional profiling might thus be more sensitive than current clinical markers for detecting kidney damage, though the profiles can differ with the route of administration. Analysis of transcripts whose expression was changed by at least twofold compared with vehicle saline after high iv and ip doses of vancomycin suggested the possibility of oxidative stress and mitochondrial damage in vancomycin-induced toxicity. In addition, our data showed changes in expression of several transcripts from the complement and inflammatory pathways. Such expression changes were confirmed by relative real-time reverse transcription–polymerase chain reaction. Finally, our results further substantiate the use of gene markers of kidney toxicity such as KIM-1/Havcr1, as indicators of renal injury
Alternative to visbreaking or delayed coking of heavy crude oil through a short contact time, solid transported bed cracking process
[EN] An extra-heavy crude oil was treated at a short contact time in the 510-580 degrees C temperature range in a FCC-like process, first thermally and then in the presence of a solid with low catalytic activity. The treatment greatly improved the properties of the crude oil, reducing the density and viscosity to values that make the oil transportable without dilution in a pipeline. In addition, the upgraded oil was substantially free of contaminants such as metals and heptane insolubles. The use of the solid allowed upgrading all properties with a minimum coke penalty. The residual fraction of the upgraded oil had to be eliminated to obtain a syncrude stable in asphaltene proof, which could be obtained by recycling to extinction in a cracking reactor.The authors thank ECOPETROL SA for material and financial support as well as permitting publishing this manuscript. Financial support by the Spanish Government-MINECO through the program "Severo Ochoa" (SEV 2016-0683), CTQ2015-70126-R (MINECO/FEDER), and by the Generalitat Valenciana through the Prometeo program (PROMETEOII/2013/011) is also acknowledged.Corma Canós, A.; Sauvanaud, LL.; Mathieu, Y.; Almanza Rubiano, L.; González Sánchez, C.; Chanaga Quiroz, T. (2018). Alternative to visbreaking or delayed coking of heavy crude oil through a short contact time, solid transported bed cracking process. Catalysis Science & Technology. 8(2):540-550. https://doi.org/10.1039/c7cy01281kS5405508
Modeling the mental health service utilization decisions of university undergraduates: A discrete choice conjoint experiment
Objective: We modeled design factors influencing the intent to use a university mental health service. Participants: Between November 2012 and October 2014, 909 undergraduates participated. Method: Using a discrete choice experiment, participants chose between hypothetical campus mental health services. Results: Latent class analysis identified three segments. A Psychological/Psychiatric Service segment (45.5%) was most likely to contact campus health services delivered by psychologists or psychiatrists. An Alternative Service segment (39.3%) preferred to talk to peer-counselors who had experienced mental health problems. A Hesitant segment (15.2%) reported greater distress but seemed less intent on seeking help. They preferred services delivered by psychologists or psychiatrists. Simulations predicted that, rather than waiting for standard counseling, the Alternative Service segment would prefer immediate access to E-Mental health. The Usual Care and Hesitant segments would wait 6 months for standard counseling. Conclusions: E-Mental Health options could engage students who may not wait for standard services.This project was supported by the Jack Laidlaw Chair in Patient-Centered Health Care and a grant from the Canadian Health Services Research Foundation
Co-development of a Best Practice Checklist for Mental Health Data Science: A Delphi Study
Background: Mental health research is commonly affected by difficulties in recruiting and retaining participants, resulting in findings which are based on a sub-sample of those actually living with mental illness. Increasing the use of Big Data for mental health research, especially routinely-collected data, could improve this situation. However, steps to facilitate this must be enacted in collaboration with those who would provide the data - people with mental health conditions.Methods: We used the Delphi method to create a best practice checklist for mental health data science. Twenty participants with both expertise in data science and personal experience of mental illness worked together over three phases. In Phase 1, participants rated a list of 63 statements and added any statements or topics that were missing. Statements receiving a mean score of 5 or more (out of 7) were retained. These were then combined with the results of a rapid thematic analysis of participants' comments to produce a 14-item draft checklist, with each item split into two components: best practice now and best practice in the future. In Phase 2, participants indicated whether or not each item should remain in the checklist, and items that scored more than 50% endorsement were retained. In Phase 3 participants rated their satisfaction with the final checklist.Results: The final checklist was made up of 14 “best practice” items, with each item covering best practice now and best practice in the future. At the end of the three phases, 85% of participants were (very) satisfied with the two best practice checklists, with no participants expressing dissatisfaction.Conclusions: Increased stakeholder involvement is essential at every stage of mental health data science. The checklist produced through this work represents the views of people with experience of mental illness, and it is hoped that it will be used to facilitate trustworthy and innovative research which is inclusive of a wider range of individuals
Continuous Hydrothermal Co-liquefaction of Aspen Wood and Glycerol with Water Phase Recirculation
FCC testing at bench scale: New units, new processes, new feeds
As the FCC process has evolved over decades, several laboratory scale equipment have appeared to maintain
a proper assessment of catalysts activity. Several laboratory equipments are available for simulating
the FCC process, from the well known fixed bed, MicroActivity Test to newer, fluid bed or transported
bed units. As well, a number of units have been created to simulate other parts of the process such as
regenerator or stripper, The increased pressure for treating non-conventional feeds, from reprocessing
gasoline to extra-heavy feeds or oils produced from biomass containing large amounts of heteroatoms,
increase the needs to have a laboratory test which is as close as possible to the process so that data
extraction from the laboratory test are simplified, thus less prone to errors or misunderstanding.Financial support by MICINN (Consolider-Ingenio 2010 MULTICAT) and MINECO (Project MAT2011-29020-0O2-02 and Subprogram for excellence Severo Ochoa, SEV 2012 0267) is gratefully acknowledged.Corma Canós, A.; Sauvanaud, LL. (2013). FCC testing at bench scale: New units, new processes, new feeds. Catalysis Today. 218-219:107-114. doi:10.1016/j.cattod.2013.03.038S107114218-21
Integrated Lipidomics in the Secreted Phospholipase A2 Biology
Mammalian genomes encode genes for more than 30 phospholipase A2s (PLA2s) or related enzymes, which are subdivided into several subgroups based on their structures, catalytic mechanisms, localizations and evolutionary relationships. More than one third of the PLA2 enzymes belong to the secreted PLA2 (sPLA2) family, which consists of low-molecular-weight, Ca2+-requiring extracellular enzymes, with a His-Asp catalytic dyad. Individual sPLA2 isoforms exhibit unique tissue and cellular localizations and enzymatic properties, suggesting their distinct pathophysiological roles. Recent studies using transgenic and knockout mice for several sPLA2 isoforms, in combination with lipidomics approaches, have revealed their distinct contributions to various biological events. Herein, we will describe several examples of sPLA2-mediated phospholipid metabolism in vivo, as revealed by integrated analysis of sPLA2 transgenic/knockout mice and lipid mass spectrometry. Knowledge obtained from this approach greatly contributes to expanding our understanding of the sPLA2 biology and pathophysiology
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