Synthesis of distillate-range fuels from biomass-derived alcohols has recently received considerable attention due to projected increases in the demands of these fuels and the extensive ...commercialization of alcohol production. Here we present a two-stage process by which an alcohol such as ethanol or 1-butanol can be converted with high yields into distillate-range ethers and olefins by combining Guerbet coupling and intermolecular dehydration. The ethers can be used as cetane-improvers in diesel fuel, while the olefins can be hydrogenated and blended with gasoline or oligomerized and hydrogenated to jet-range paraffins. The first stage was executed using calcium hydroxyapatite to produce higher linear and branched alcohols at above 80% selectivity at up to 40% conversion with high stability for over 400 h time-on-stream operation. Increasing conversion decreases selectivity, producing predominantly mono-ene and diene byproducts. Etherification was performed using the acidic resin Amberlyst™ 70 at around 65% conversion. Linear alcohols were converted at above 90% selectivity while branched alcohols were far more selective to olefins (65-75%). Etherification occurs
via
two mechanisms: a direct mechanism involving the reaction of two alcohols and an indirect mechanism between an alcohol and equilibrated pool of olefins. Cross-etherification was observed between linear and branched alcohols, improving the selectivity to ethers in conversion of the latter. A mixture of C
4+
alcohols produced from ethanol condensation at 40% conversion was effectively utilized in etherification at selectivities comparable to the model mixtures. An overall process is presented for the conversion of ethanol to diesel-range ethers and olefins with yields of approximately 80%.
Ethanol can be converted to heavy diesel ethers and jet fuel precursor olefins through sequential Guerbet coupling and dehydration.
Guerbet coupling to oligomerize ethanol to heavy alcohols over a hydroxyapatite (HAP) catalyst is explored through the development and application of a reaction kinetics model that describes coupling ...to higher alcohols, condensation to “interrupted coupling products” such as dienes and aromatics, and direct unimolecular dehydration to monoenes. The kinetic data collected to develop this model includes ethanol, 1-butanol, and water–ethanol feeds at 350 °C, 1 bar, and between 3 and 20% conversion over HAP. The model consists of nine kinetic parameters describing 647 reactions among 185 alcohols. Inhibition from byproduct water leads to decreases in reaction rates and alcohol selectivities as conversion increases, which the model can accurately predict at 60% conversion at over 8 times the highest contact time used in model development. The modified step-growth kinetics underlying the model also accurately predict alcohol distributions at this conversion. Further extrapolations clarify how these kinetics (modified step growth wherein branched alcohols do not act nucleophilically) in addition to inhibition and side reactions affect the potential use of direct ethanol oligomerization to selectively produce heavy alcohols with HAP. Further deviations from step-growth kinetics can be modeled via manipulation of the apparent nucleophilicity and electrophilicity of ethanol relative to higher alcohols. Catalysts that could increase the nucleophilicity would lead to higher product linearities, while catalysts that decrease the electrophilicity would lead to heavier alcohol distributions at fixed conversion.
Hydroxychloroquine has not been associated with improved survival among hospitalized COVID-19 patients in the majority of observational studies and similarly was not identified as an effective ...prophylaxis following exposure in a prospective randomized trial. We aimed to explore the role of hydroxychloroquine therapy in mildly symptomatic patients diagnosed in the outpatient setting.
We examined the association between outpatient hydroxychloroquine exposure and the subsequent progression of disease among mildly symptomatic non-hospitalized patients with documented SARS-CoV-2 infection. The primary outcome assessed was requirement of hospitalization. Data was obtained from a retrospective review of electronic health records within a New Jersey USA multi-hospital network. We compared outcomes in patients who received hydroxychloroquine with those who did not applying a multivariable logistic model with propensity matching.
Among 1274 outpatients with documented SARS-CoV-2 infection 7.6% were prescribed hydroxychloroquine. In a 1067 patient propensity matched cohort, 21.6% with outpatient exposure to hydroxychloroquine were hospitalized, and 31.4% without exposure were hospitalized. In the primary multivariable logistic regression analysis with propensity matching there was an association between exposure to hydroxychloroquine and a decreased rate of hospitalization from COVID-19 (OR 0.53; 95% CI, 0.29, 0.95). Sensitivity analyses revealed similar associations. QTc prolongation events occurred in 2% of patients prescribed hydroxychloroquine with no reported arrhythmia events among those with data available.
In this retrospective observational study of SARS-CoV-2 infected non-hospitalized patients hydroxychloroquine exposure was associated with a decreased rate of subsequent hospitalization. Additional exploration of hydroxychloroquine in this mildly symptomatic outpatient population is warranted.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Here, we show that C
4
-C
12
linear olefins, including linear alpha olefins, can be selectively produced from ethylene over a stable cobalt oxide on carbon catalyst. Both bulk and surface cobalt ...phases are CoO when the catalyst is stable, suggesting CoO is the stable cobalt phase for oligomerization. During the reaction, polyethylene forms in the catalyst pores which influences the product selectivity. The catalyst is more stable at higher temperatures (∼200 °C) likely due to reduction of Co
3
O
4
to CoO while rapid deactivation is observed at lower temperatures (
e.g.
, 80-140 °C). The product selectivity can be fit to two different Schulz Flory distributions, one from C
4
to C
10
olefins and one above C
10
olefins, suggesting that transport restrictions influence product selectivity. At 48.3% conversion, product linearities up to C
12
olefins are above 90%, making it the most selective heterogeneous catalyst to linear olefins to date in the absence of activators and/or solvents.
Stable heterogeneous cobalt oxide on carbon catalyst for ethylene oligomerization into linear and alpha olefins.
Correction for 'Catalytic synthesis of distillate-range ethers and olefins from ethanol through Guerbet coupling and etherification' by Nathaniel M. Eagan
et al.
,
Green Chem.
, 2019,
21
, 3300-3318.
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IMPORTANCE: Accurate and up-to-date estimates on incidence, prevalence, mortality, and disability-adjusted life-years (burden) of neurological disorders are the backbone of evidence-based health care ...planning and resource allocation for these disorders. It appears that no such estimates have been reported at the state level for the US. OBJECTIVE: To present burden estimates of major neurological disorders in the US states by age and sex from 1990 to 2017. DESIGN, SETTING, AND PARTICIPANTS: This is a systematic analysis of the Global Burden of Disease (GBD) 2017 study. Data on incidence, prevalence, mortality, and disability-adjusted life-years (DALYs) of major neurological disorders were derived from the GBD 2017 study of the 48 contiguous US states, Alaska, and Hawaii. Fourteen major neurological disorders were analyzed: stroke, Alzheimer disease and other dementias, Parkinson disease, epilepsy, multiple sclerosis, motor neuron disease, migraine, tension-type headache, traumatic brain injury, spinal cord injuries, brain and other nervous system cancers, meningitis, encephalitis, and tetanus. EXPOSURES: Any of the 14 listed neurological diseases. MAIN OUTCOME AND MEASURE: Absolute numbers in detail by age and sex and age-standardized rates (with 95% uncertainty intervals) were calculated. RESULTS: The 3 most burdensome neurological disorders in the US in terms of absolute number of DALYs were stroke (3.58 95% uncertainty interval UI, 3.25-3.92 million DALYs), Alzheimer disease and other dementias (2.55 95% UI, 2.43-2.68 million DALYs), and migraine (2.40 95% UI, 1.53-3.44 million DALYs). The burden of almost all neurological disorders (in terms of absolute number of incident, prevalent, and fatal cases, as well as DALYs) increased from 1990 to 2017, largely because of the aging of the population. Exceptions for this trend included traumatic brain injury incidence (−29.1% 95% UI, −32.4% to −25.8%); spinal cord injury prevalence (−38.5% 95% UI, −43.1% to −34.0%); meningitis prevalence (−44.8% 95% UI, −47.3% to −42.3%), deaths (−64.4% 95% UI, −67.7% to −50.3%), and DALYs (−66.9% 95% UI, −70.1% to −55.9%); and encephalitis DALYs (−25.8% 95% UI, −30.7% to −5.8%). The different metrics of age-standardized rates varied between the US states from a 1.2-fold difference for tension-type headache to 7.5-fold for tetanus; southeastern states and Arkansas had a relatively higher burden for stroke, while northern states had a relatively higher burden of multiple sclerosis and eastern states had higher rates of Parkinson disease, idiopathic epilepsy, migraine and tension-type headache, and meningitis, encephalitis, and tetanus. CONCLUSIONS AND RELEVANCE: There is a large and increasing burden of noncommunicable neurological disorders in the US, with up to a 5-fold variation in the burden of and trends in particular neurological disorders across the US states. The information reported in this article can be used by health care professionals and policy makers at the national and state levels to advance their health care planning and resource allocation to prevent and reduce the burden of neurological disorders.
Abstract
Context
Total thyroidectomy in pediatric papillary thyroid carcinoma (PTC) is recommended in national guidelines because of the high incidence of multifocal disease (MFD).
Objective
To ...determine the incidence of MFD in childhood and adolescent vs adult PTC and whether MFD is a predictor for poorer outcomes in childhood and adolescent PTC.
Methods
We conducted an institutional review board-approved review of patients with PTC undergoing surgery (1986-2021) at Memorial Sloan Kettering Cancer Center. Clinical and pathological characteristics in patients with unifocal disease (UFD) and MFD were compared using Pearson's χ2 test. Survival outcomes were analyzed using the Kaplan-Meier method and log-rank test. Multivariate analysis assessed the impact of MFD on outcome.
Results
MFD was less common in childhood and adolescent patients with PTC (45%; 127/283) than in adults (54%; 3023/5564; P = .002). Childhood and adolescent patients with UFD and MFD had similar tumor stage and PTC subtype at presentation, with no significant difference in histopathologic features. Median follow-up was 68 months. There was no significant difference in 5-year recurrence-free probability and overall survival was 100% in both groups. There was no significant difference in 5-year contralateral lobe PTC-free probability between patients with UFD and MFD treated with lobectomy. Multivariate analysis showed MFD was not a predictor for recurrence.
Conclusion
MFD was less common in childhood and adolescent patients with PTC than adults and was not a predictor of poor outcome on multivariate analysis, with excellent long-term outcomes in all patients with PTC. MFD does not appear to warrant completion thyroidectomy in childhood and adolescent patients selected for lobectomy.
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