Process development and economic analysis of carbon dioxide to dimethyl carbonate

This study developed a strategy for production of dimethyl carbonate from flue gas. In this strategy, Carbon dioxide is captured from flue gas by using monoethanolamine-based carbon dioixde absorption/desorption subsystems. Then, captured carbon dioxide is converted to dimethyl carbonate over a CeO2 catalyst. This study designed a heat exchanger network for reducing energy requirements of our process. The technoeconomic evaluation of this study shows that the integrated process strategy results in a minimum selling price of US$2.06 per kg.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

Process synthesis and analysis of catalytic biofuel production from separate conversion of hemicellulose and cellulose using lignin-derived alkylphenol solvents

We develop a process in which the cellulose and hemicellulose fractions of lignocellulosic biomass are converted separately to jet fuel-range liquid hydrocarbon fuels(butene oligomers(BO)) while alkylphenol solvents (propyl guaiacol (PG) and propyl syringol (PS)) are produced from the lignin fraction through catalytic conversion subsystems. In this process dilute sulfuric acid (SA)-catalyzed pretreatment fractionates the biomass into insoluble cellulose and soluble hemicellulose-derived xylose, and they then are converted separately to levulinic acid (LA) using 2-sec-butylphenol (SBP) and lignin-derived alkylphenol solvents (LDS), respectively. The LA is converted catalytically to BO, passing through γ-valerolactone (GVL) and butene platforms. This process leads to a high biomass-to-fuels yield (34.8 mol%) at low concentrations of biomass derivatives using large volumes of solvents. Therefore, we design separation subsystems for recovering the alkylphenol solvents and biomass derivatives to be combined with the catalytic conversion subsystems of hemicellulose, cellulose and lignin. We then show a heat exchanger network (HEN) design to satisfy total energy requirements of the process from combustion of biomass degradation products. Finally, our economic analysis shows that the process design using corn stover feedstock leads to a minimum selling price of $3.37 per gallon of gasoline equivalent for jet fuel-range liquid hydrocarbon fuels, which suggests that it is an economically competitive alternative to current biofuels production approaches as a result of iterative experimental and computational efforts.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

Spatially resolved penetration depth measurements and vortex manipulation in the ferromagnetic superconductor ErNi2B2C

We present a local probe study of the magnetic superconductor, ErNi$_2$B$_2$C, using magnetic force microscopy at sub-Kelvin temperatures. ErNi$_2$B$_2$C is an ideal system to explore the effects of concomitant superconductivity and ferromagnetism. At 500 mK, far below the transition to a weakly ferromagnetic state, we directly observe a structured magnetic background on the micrometer scale. We determine spatially resolved absolute values of the magnetic penetration depth $\lambda$ and study its temperature dependence as the system undergoes magnetic phase transitions from paramagnetic to antiferromagnetic, and to weak ferromagnetic, all within the superconducting regime. In addition, we estimate the absolute pinning force of Abrikosov vortices, which shows a position- and temperature dependence as well, and discuss the possibility of the purported spontaneous vortex formation

A lignocellulosic ethanol strategy via nonenzymatic sugar production: Process synthesis and analysis

The work develops a strategy for the production of ethanol from lignocellulosic biomass. In this strategy, the cellulose and hemicellulose fractions are simultaneously converted to sugars using a γ-valerolactone (GVL) solvent containing a dilute acid catalyst. To effectively recover GVL for reuse as solvent and biomass-derived lignin for heat and power generation, separation subsystems, including a novel CO2-based extraction for the separation of sugars from GVL, lignin and humins have been designed. The sugars are co-fermented by yeast to produce ethanol. Furthermore, heat integration to reduce utility requirements is performed. It is shown that this strategy leads to high ethanol yields and the total energy requirements could be satisfied by burning the lignin. The integrated strategy using corn stover feedstock leads to a minimum selling price of $5 per gallon of gasoline equivalent, which suggests that it is a promising alternative to current biofuels production approaches

Longitudinal Patterns in Antithrombotic Therapy in Patients with Atrial Fibrillation after Percutaneous Coronary Intervention in the Non-Vitamin K Oral Anticoagulant Era:A Nationwide Population-Based Study

We investigated whether longitudinal patterns in antithrombotic therapy have changed after the introduction of non-vitamin K oral anticoagulants (NOACs) in patients with atrial fibrillation (AF) who underwent percutaneous coronary intervention (PCI). Using a claims database of the Korean AF population who underwent PCI between 2012 and 2016 (n = 18,691), we analyzed prescription records of oral anticoagulants (OACs) and antiplatelets at 3-month intervals over 2 years after PCI. The study population was stratified (pre-NOAC, transition, and NOAC era) using time-periods of NOAC introduction in Korea and an expansion of reimbursement for NOAC in AF as indicators. The overall rates of OAC were low at baseline (24.9%, 26.9%, and 35.2% in pre-NOAC, transition, and NOAC era, respectively), contrary to high rates of dual antiplatelet therapy (DAPT) (73.3%, 71.4%, and 63.6%). However, OAC prescription rates were increased at 1-year (18.5%, 22.5%, and 31.6%), and 2-year follow-up (17.8%, 24.2%, and 31.8%) from pre-NOAC to NOAC era. In NOAC era, 63.5% of baseline OAC prescriptions comprised NOAC, of which 96.4% included triple therapy with DAPT. Over 2 years, we observed increasing rates of double therapy with a single antiplatelet (18.3% and 20.0% at 1- and 2-year follow-up) and OAC monotherapy (2.7% and 8.9% at 1- and 2-year follow-up)

Net clinical benefit of antithrombotic therapy for atrial fibrillation patients with stable coronary artery disease

OBJECTIVES: To compare the net clinical benefit of oral anticoagulant (OAC) monotherapy to OAC plus single antiplatelet therapy (SAPT) in patients with atrial fibrillation (AF) and stable coronary artery disease (CAD) at 1- and 3-year after percutaneous coronary intervention (PCI). BACKGROUND: It has not been studied whether the net clinical benefit of the antithrombotic treatment options differs depending on the elapsed time from the index PCI. METHODS: Using the Korean nationwide claims database, we included AF patients who underwent PCI from 2009 to 2019 and constructed two cohorts: 1- and 3-year after PCI. In each cohort, the baseline characteristics of two groups were balanced using propensity score weighting. Ischemic stroke, myocardial infarction, major bleeding, and composite clinical outcomes were analyzed. RESULTS: Among patients with 1-year after PCI, OAC monotherapy (n = 678), and OAC plus SAPT (n = 3,159) showed comparable results for all clinical outcomes. In patients with 3-year after PCI, OAC monotherapy (n = 1,038) and OAC plus SAPT (n = 2,128) showed comparable results for ischemic stroke and myocardial infarction, but OAC monotherapy was associated with a lower risk of composite clinical outcomes (HR 0.762, 95% CI 0.607–0.950), mainly driven by the reduction of major bleeding risk (HR 0.498, 95% CI 0.345–0.701). CONCLUSION: Oral anticoagulant monotherapy may be a comparable choice for patients with AF and stable CAD compared to OAC plus SAPT. In patients with stable CAD more than 3-year after index PCI, OAC monotherapy would be a better choice, being associated with less major bleeding and a positive net clinical benefit