46 research outputs found
Comparative assessment of gasification based coal power plants with various CO2 capture technologies producing electricity and hydrogen
Seven different types of gasification-based coal conversion processes for producing mainly electricity and in some cases hydrogen (H2), with and without carbon dioxide (CO2) capture, were compared on a consistent basis through simulation studies. The flowsheet for each process was developed in a chemical process simulation tool “Aspen Plus”. The pressure swing adsorption (PSA), physical absorption (Selexol), and chemical looping combustion (CLC) technologies were separately analyzed for processes with CO2 capture. The performances of the above three capture technologies were compared with respect to energetic and exergetic efficiencies, and the level of CO2 emission. The effect of air separation unit (ASU) and gas turbine (GT) integration on the power output of all the CO2 capture cases is assessed. Sensitivity analysis was carried out for the CLC process (electricity-only case) to examine the effect of temperature and water-cooling of the air reactor on the overall efficiency of the process. The results show that, when only electricity production in considered, the case using CLC technology has an electrical efficiency 1.3% and 2.3% higher than the PSA and Selexol based cases, respectively. The CLC based process achieves an overall CO2 capture efficiency of 99.9% in contrast to 89.9% for PSA and 93.5% for Selexol based processes. The overall efficiency of the CLC case for combined electricity and H2 production is marginally higher (by 0.3%) than Selexol and lower (by 0.6%) than PSA cases. The integration between the ASU and GT units benefits all three technologies in terms of electrical efficiency. Furthermore, our results suggest that it is favorable to operate the air reactor of the CLC process at higher temperatures with excess air supply in order to achieve higher power efficiency
Clinically Actionable Hypercholesterolemia and Hypertriglyceridemia in Children with Nonalcoholic Fatty Liver Disease
OBJECTIVE:
To determine the percentage of children with nonalcoholic fatty liver disease (NAFLD) in whom intervention for low-density lipoprotein cholesterol or triglycerides was indicated based on National Heart, Lung, and Blood Institute guidelines.
STUDY DESIGN:
This multicenter, longitudinal cohort study included children with NAFLD enrolled in the National Institute of Diabetes and Digestive and Kidney Diseases Nonalcoholic Steatohepatitis Clinical Research Network. Fasting lipid profiles were obtained at diagnosis. Standardized dietary recommendations were provided. After 1 year, lipid profiles were repeated and interpreted according to National Heart, Lung, and Blood Institute Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction. Main outcomes were meeting criteria for clinically actionable dyslipidemia at baseline, and either achieving lipid goal at follow-up or meeting criteria for ongoing intervention.
RESULTS:
There were 585 participants, with a mean age of 12.8 years. The prevalence of children warranting intervention for low-density lipoprotein cholesterol at baseline was 14%. After 1 year of recommended dietary changes, 51% achieved goal low-density lipoprotein cholesterol, 27% qualified for enhanced dietary and lifestyle modifications, and 22% met criteria for pharmacologic intervention. Elevated triglycerides were more prevalent, with 51% meeting criteria for intervention. At 1 year, 25% achieved goal triglycerides with diet and lifestyle changes, 38% met criteria for advanced dietary modifications, and 37% qualified for antihyperlipidemic medications.
CONCLUSIONS:
More than one-half of children with NAFLD met intervention thresholds for dyslipidemia. Based on the burden of clinically relevant dyslipidemia, lipid screening in children with NAFLD is warranted. Clinicians caring for children with NAFLD should be familiar with lipid management
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Incidence of Type 2 Diabetes in Children With Nonalcoholic Fatty Liver Disease
Background & aimsType 2 diabetes (T2D) is a growing problem in children. Children with NAFLD are at potentially high risk for developing T2D; however, the incidence of T2D in this population is unknown. This study aimed to determine the incidence of T2D in children with NAFLD and identify associated risk factors.MethodsChildren with NAFLD enrolled in the Nonalcoholic Steatohepatitis Clinical Research Network were followed longitudinally. Incidence of T2D was determined by using clinical history and fasting laboratory values. Cumulative incidence curves were developed for time to T2D. A Cox regression multivariable model was constructed using best subsets Akaike's Information Criteria selection.ResultsThis study included 892 children with NAFLD and with a mean age of 12.8 years (2.7) followed for 3.8 years (2.3) with a total 3234 person-years at risk. The incidence rate of T2D was 3000 new cases per 100,000 person-years at risk. At baseline, 63 children had T2D, and during follow-up, an additional 97 children developed incident T2D, resulting in a period prevalence of 16.8%. Incident T2D was significantly higher in females versus males (hazard ratio [HR], 1.8 [1.0-2.8]), associated with BMI z-score (HR, 1.8 [1.0-3.0]), and more severe liver histology including steatosis grade (HR, 1.3 [1.0-1.7]), and fibrosis stage (HR, 1.3 [1.0-1.5]).ConclusionsChildren with NAFLD are at high risk for existing and incident T2D. In addition to known risk factors for T2D (female and BMI z-score), severity of liver histology at the time of NAFLD diagnosis was independently associated with T2D development. Targeted strategies to prevent T2D in children with NAFLD are needed
Competitive H2S – CO2 absorption in reactive aqueous methyldiethanolamine solution: Prediction with ePC-SAFT
Reactive absorption of CO2 and H2S in aqueous methyldiethanolamine (MDEA) solutions is considered within the ePC-SAFT equation of state. We demonstrate that ePC-SAFT can be employed in a predictive manner without regression of additional temperature-correlated terms. Mixed system predictions are tested using a consistent set experimental data covering a wide range of temperatures (313 K\u2013413 K), partial pressures (0.001 kPa\u20131000 kPa), and MDEA mass fractions (0.05\u2013wMDEA 0.75 wMDEA). Predicted partial pressures for acid gas absorption show good agreement for low MDEA fractions (wMDEA < 0.5). Absorption selectivity in binary H2S + CO2 absorption is correctly predicted, with absolute average deviations of 57.18% and 79.32% for partial pressures of CO2 and H2S. We identify a significant deterioration in ePC-SAFT predictive power for the high-MDEA regime (wMDEA > 0.5), likely originating from underlying assumptions in the Debye-H\ufcckel electrolyte free energy treatment and representation of ionic species
Crafted:An exploratory database of simulated adsorption isotherms of metal-organic frameworks
Overview
The files in this repository compose the Charge-dependent, Reproducible, Accessible, Forcefield-dependent, and Temperature-dependent Exploratory Database (CRAFTED) of adsorption isotherms. This dataset contains the simulation of CO2 and N2 adsorption isotherms on 690 metal-organic frameworks taken from the CoRE MOF 2014 database. The simulations were performed with two force fields (UFF and DREIDING), six partial charge schemes (no charges, Qeq, EQeq, DDEC, MPNN, and PACMOF), and three temperatures (273, 298, 323 K).
Contents
CIF_FILES/ contains 6 folders (NEUTRAL, DDEC, EQeq, Qeq, MPNN, and PACMOF), each one with 690 CIF files;
FORCEFIELDS/ contains 2 folders (UFF and DREIDING) with the definition of the forcefields;
INPUT_FILES/ contains 49,680 input files for the GCMC simulations;
ISOTHERM_FILES/ contains 49,680 adsorption isotherms resulting from the GCMC simulation;
ENTHALPY_FILES/ contains 49,680 enthalpies of adsorption from the isotherms;
RAC_DBSCAN/ contains the RAC and geometrical descriptors to perform the t-NSE + DBSCAN analysis;
Licenses
The CIF files in the DDEC folder were downloaded from CoRE MOF 2014 and are licensed under the terms of the Creative Commons Attribution 4.0 International license (CC-BY-4.0).
Dalar Nazarian, Jeffrey S. Camp, & David S. Sholl. (2016). Computation-Ready Experimental Metal-Organic Framework (CoRE MOF) 2014 DDEC Database [Data set]. Zenodo.
The CO2.def and N2.def forcefield files were downloaded from RASPA and are licensed under the terms of the MIT license.
RASPA: a molecular-dynamics, monte-carlo and optimization code for nanoporous materials.
Copyright (C) 2006-2019 David Dubbeldam, Sofia Calero, Thijs Vlugt, Donald E. Ellis, and Randall Q. Snurr.
The CIF files in the PACMOF, MPNN, Qeq, EQeq and NEUTRAL folders were derived from those in the DDEC folder and are licensed under the terms of the Creative Commons Attribution 4.0 International license (CC-BY-4.0).
All remaining files are licensed under the terms of the CDLA-Sharing-1.0 license.
Software requirements
In order to create a Python environment capable of running the Jupyter notebooks, please install conda and execute
conda env create --file environment.yml
Usage instructions
Execute the command below to run JupyterLab in the appropriate Python environment.
conda run --name crafted jupyter-labCreated using "tar -Jcvf CRAFTED-1.1.1.tar.xz CRAFTED-1.1.1/"