ABSTRACT
A variety of amine-impregnated porous solid sorbents for direct air capture (DAC) of CO2 have been developed, yet the effect of amine-solid support interactions on the CO2 adsorption behavior is still poorly understood. When tetraethylenepentamine (TEPA) is impregnated on two different supports, commercial γ-Al2O3 and MIL-101(Cr), they show different trends in CO2 sorption when the temperature (-20 to 25 °C) and humidity (0-70% RH) of the simulated air stream are varied. In situ IR spectroscopy is used to probe the mechanism of CO2 sorption on the two supported amine materials, with weak chemisorption (formation of carbamic acid) being the dominant pathway over MIL-101(Cr)-supported TEPA and strong chemisorption (formation of carbamate) occurring over γ-Al2O3-supported TEPA. Formation of both carbamic acid and carbamate species is enhanced over the supported TEPA materials under humid conditions, with the most significant enhancement observed at -20 °C. However, while equilibrium H2O sorption is high at cold temperatures (e.g., -20 °C), the effect of humidity on a practical cyclic DAC process is expected to be minimal due to slow H2O uptake kinetics. This work suggests that the CO2 capture mechanisms of impregnated amines can be controlled by adjusting the degree of amine-solid support interaction and that H2O adsorption behavior is strongly affected by the properties of the support materials. Thus, proper selection of solid support materials for amine impregnation will be important for achieving optimized DAC performance under varied deployment conditions, such as cold (e.g., -20 °C) or ambient temperature (e.g., 25 °C) operations.
ABSTRACT
BACKGROUND: Patients with the myeloproliferative neoplasms (MPNs) myelofibrosis (MF), polycythemia vera (PV), and essential thrombocythemia (ET) are at increased risk for thrombotic and cardiovascular events and experience a variety of burdensome symptoms. However, there is a paucity of data in the biomedical literature about how MPNs impact productivity in the workplace. This analysis of the Living with MPNs survey was conducted to evaluate the impact of MPNs on employment, career potential, and work productivity. METHODS: This cross-sectional online survey included respondents aged 18-70 years living in the United States with a diagnosis of MF, PV, or ET. The survey consisted of ~ 100 questions related to MPN diagnosis, disease-related medical history, MPN-related symptoms and functional status, changes in employment and work productivity, and impact on daily activities since diagnosis. The MPN Symptom Assessment Form Total Symptom Score (MPN-SAF TSS) was used to assess symptom burden. The Work Productivity and Activity Impairment Specific Health Problem questionnaire (WPAI-SHP) was used to assess the effects of MPNs on work productivity and activity (7-day recall) among currently employed respondents. Correlations between MPN-SAF TSS and WPAI-SHP scores were calculated using Spearman's coefficients. RESULTS: Of 904 respondents, 592 were employed (MF, n = 174; PV, n = 248; ET, n = 170) at the time of their MPN diagnosis. Approximately half (50.5%) of the 592 employed survey respondents reported ≥1 change in employment status because of their diagnosis, most commonly "left a job" (30.2%) "went on medical disability leave" (24.8%), and "had reductions in work hours for at least 3 months" (21.8%). Among respondents who remained employed at the time of survey participation (n = 398), mean WPAI-SHP scores were as follows: absenteeism, 6.9%; presenteeism, 27.4%; overall work impairment, 31.1%; and activity impairment, 32.8%. WPAI-SHP scores positively correlated with MPN-SAF TSS (correlation coefficients, 0.37-0.70; P < 0.001). CONCLUSIONS: Half of the employed respondents had an employment status change (eg, leaving a job, medical disability leave, early retirement) because of their disease since the diagnosis. Currently employed respondents reported meaningful impairments in work productivity and activities of daily living that were attributable to their MPNs, and the degree of impairments highlighted the severity of symptom burden.
