Insights into the ceria-catalyzed ketonization reaction for biofuels applications

The ketonization of small organic acids is a valuable reaction for biorenewable applications. Ceria has long been used as a catalyst for this reaction; however, under both liquid and vapor phase conditions, it was found that given the right temperature regime of about 150-300 °C, cerium oxide, which was previously believed to be a stable catalyst for ketonization, can undergo bulk transformations. This result, along with other literature reports, suggest that the long held belief of two separate reaction pathways for either bulk or surface ketonization reactions are not required to explain the interaction of cerium oxide with organic acids. X-ray photon spectroscopy, scanning electron microscopy, and temperature programmed decomposition results supported the formation of metal acetates and explained the occurrence of cerium reduction as well as the formation of cerium oxide/acetate whiskers. After thermogravimetry/mass spectrometry and FT-IR experiments, a single reaction sequence is proposed that can be applied to either surface or bulk reactions with ceria

Effect of Gas Atmosphere on Catalytic Behaviour of Zirconia, Ceria and Ceria Zirconia Catalysts in Valeric Acid Ketonization

[EN] Ketonization of valeric acid, which can be obtained by lignocellulosic biomass conversion, was carried out in a fixed bed flow reactor over ZrO2, 5-20 % CeO2/ZrO2 and CeO2 both under hydrogen and nitrogen stream at 628 K and atmospheric pressure. Regardless gas-carrier 10 wt% CeO2/ZrO2 was found to show higher catalytic activity compared to zirconia per se as well as other ceria modified zirconia while ceria per se exhibited very low catalytic activity. All catalysts provided higher acid conversion in H-2 than in N-2 whereas selectivity to 5-nonanone was insensitive to gas atmosphere. XRD, FTIR, UV-Vis DRS, XPS, HRTEM methods were applied to characterize catalysts in reduced and unreduced states simulating corresponding reaction conditions during acid ketonization. XRD did not reveal any changes in zirconia and ceria/zirconia lattice parameters as well as crystalline phase depending on gas atmosphere while insertion of ceria in zirconia caused notable increase in lattice parameter indicating some distortion of crystalline structure. According to XPS, FTIR and UV-Vis methods, the carrier gas was found to affect catalyst surface composition leading to alteration in Lewis acid sites ratio. Appearance of Zr3+ cations was observed on the ZrO2 surface after hydrogen pretreatment whereas only Zr4+ cations were determined using nitrogen as a gas-carrier. These changes of catalyst's surface cation composition affected corresponding activity in ketonization probably being crucial for reaction mechanism involving metal cations catalytic centers for acid adsorption and COO- stabilization at the initial step.Financial support from the Russian Foundation of Basic Research (RFBR Grant No 11-03-94001-CSIC) is gratefully acknowledged. This work was supported by the Federal Program "Scientific and Educational Cadres of Russia'' (Grant No 2012-1.5-12-000-1013-002). The authors also wish to thank Dr. Evgeniy Gerasimov, Dr. Igor Prosvirin, Dr. Demid Demidov from the Department of Physicochemical Methods at the Boreskov Institute of Catalysis for TEM and XPS measurements.Zaytseva, YA.; Panchenko, VN.; Simonov, MN.; Shutilov, AA.; Zenkovets, GA.; Renz, M.; Simakova, IL.... (2013). Effect of Gas Atmosphere on Catalytic Behaviour of Zirconia, Ceria and Ceria Zirconia Catalysts in Valeric Acid Ketonization. Topics in Catalysis. 56(9-10):846-855. https://doi.org/10.1007/s11244-013-0045-yS846855569-10Alonso DM, Bond JQ, Dumesic JA (2010) Green Chem 12:1493–1513Serrano-Ruiz JC, Wang D, Dumesic JA (2010) Green Chem 12:574–577Malhotra SL, Wong RW, Breton MP (2002) Patent US 6461417Westfechtel A, Breucker C, Gutsche B, Jeromin L, Eierdanz H, Baumann H, Schmid KH, Nonnenkamp W (1993) Patent DE 4121117Seipel W, Hensen H, Boyxen N (2001) Patent DE 19958521Tomlinson AD (2001) Patent WO 2001094522Glinski M, Kijenski J, Jakubowski A (1995) Appl Catal A Gen 128:209–217Glinski M, Kijenski J (2000) React Kinet Catal Lett 69:123–128Parida K, Mishra HK (1999) J Mol Catal A Chem 139:73–80Serrano-Ruiz JC, Dumesic JA (2009) Green Chem 11:1101–1104Serrano-Ruiz JC, Dumesic JA (2009) ChemSusChem 2:581–586Leung A, Boocock DGB, Konar SK (1995) Energy Fuels 9:913–920Gaertner CA, Serrano-Ruiz JC, Braden DJ, Dumesic JA (2010) Ind Eng Chem Res 49:6027–6033Saito N (1996) Patent JP 08198796Yakerson VI, Rubinshtein AM, Gorskaya LA (1970) Patent GB 1208802Graille J, Pioch D (1991) Patent EP 457665Pioch D, Lescure R, Graille J (1995) Ol Corps Gras Lipides 2:386–389Mueller-Erlwein E, Rosenberger B (1990) Chem Ing Tech 62:512–513Corma A, Renz M, Schaverien C (2008) ChemSusChem 1:739–741Bayer (1911) Patent DE 256622Vavon G, Apchie A (1928) Bull Soc Chim 43:667–677Thorpe JF, Kon GAR (1941) Org Synth 1:192–194Nagashima O, Sato S, Takahashi R, Sodesawa T (2005) J Mol Catal A Chem 227:231–239Klein-Homann W (1988) Patent DE 3709765Stubenrauch J, Brisha E, Vohs JM (1996) Catal Today 28:431–441Pulido A, Oliver-Tomas B, Renz M, Boronat M, and Corma A (2013) ChemSusChem 6:141–151Hendren TS, Dooley KM (2003) Catal Today 85:333–351Novothy R, Paulsen S (1963) Patent DE 1158050Kim KS, Barteau MA (1990) J Catal 125:353–375Pestman R, Van Duijne A, Pieterse JAZ, Ponec V (1995) J Mol Catal A 103:175–180Martinez R, Huff MC, Barteau MA (2004) J Catal 222:404–409Matsuoka K, Tagawa K (1985) Patent JP 61207354Shutilov AA, Simonov MN, Zaytseva YuA, Zenkovets GA, and Simakova IL (2013) Kinet Catal 54:184–192Kuriacose JC, Swaminathan R (1969) J Catal 14:348–354Swaminathan R, Kuriacose JC (1970) J Catal 16:357–362Cressely J, Farkhani D, Deluzarche A, Kiennemann A (1984) Mater Chem Phys 11:413–431Kuriacose JC, Jewur SS (1977) J Catal 50:330–341Renz M, Corma A (2004) Eur J Org Chem 2004:2036–2039Taimoor AA, Favre-Reguillon A, Vanoye L, Pitault I (2012) Catal Sci Technol 2:359–363Kustov LM (1997) Top Catal 4:131–144Emmanuel NM (1978) Usp Khim 8:1329–1396Kaspar J, Fornasiero P (2002) In: Trovarelli A (ed) Catalysis by ceria and related materials. Imperial College Press, LondonReddy DD, Chowdhury B, Smirniotis PG (2001) Appl Catal A Gen 211:19–30Rango R, Kaspar G, Meriani S, di Monte R, Graziani M (1994) Catal Lett 24:107–112Rao G, Sahu H (2001) Proc Indian Acad Sci (Chem Sci) 113:651–658Navío JA, Hidalgo MC, Colón G, Botta SG, Litter MI (2001) Langmuir 17:202–210Timofeeva MN, Jhung SH, Hwang YK, Kim DK, Panchenko VN, Melgunov MS, Chesalov YA, Chang JS (2007) Appl Catal A Gen 317:1–10Kaneko H, Taku S, Tamaura Y (2011) Sol Energy 85:2321–2330Maia TA, Assaf JM, Assaf EM (2012) Mater Chem Phys 132:1029–1034Zhou HP, Si R, Song WG, Yan CH (2009) J Solid State Chem 182:2475–2485Si R, Zhang YW, Li SJ, Lin BX, Yan CH (2004) J Phys Chem B 108:12481–12488Hadjivanov KI, Vayssilov GN (2002) Adv Catal 47:307–511Vivier L, Duprez D (2010) ChemSusChem 3:654–678Vidruk R, Landau MV, Herskowitz M, Ezersky V, Goldbourt A (2011) J Catal 282:215–227Binet C, Daturi M, Lavalley JC (1999) Catal Today 50:207–225Conesa J (1995) Surf Sci 339:337–35

Clinical and organizational factors associated with mortality during the peak of first COVID-19 wave: the global UNITE-COVID study

Purpose: To accommodate the unprecedented number of critically ill patients with pneumonia caused by coronavirus disease 2019 (COVID-19) expansion of the capacity of intensive care unit (ICU) to clinical areas not previously used for critical care was necessary. We describe the global burden of COVID-19 admissions and the clinical and organizational characteristics associated with outcomes in critically ill COVID-19 patients. Methods: Multicenter, international, point prevalence study, including adult patients with SARS-CoV-2 infection confirmed by polymerase chain reaction (PCR) and a diagnosis of COVID-19 admitted to ICU between February 15th and May 15th, 2020. Results: 4994 patients from 280 ICUs in 46 countries were included. Included ICUs increased their total capacity from 4931 to 7630 beds, deploying personnel from other areas. Overall, 1986 (39.8%) patients were admitted to surge capacity beds. Invasive ventilation at admission was present in 2325 (46.5%) patients and was required during ICU stay in 85.8% of patients. 60-day mortality was 33.9% (IQR across units: 20%–50%) and ICU mortality 32.7%. Older age, invasive mechanical ventilation, and acute kidney injury (AKI) were associated with increased mortality. These associations were also confirmed specifically in mechanically ventilated patients. Admission to surge capacity beds was not associated with mortality, even after controlling for other factors. Conclusions: ICUs responded to the increase in COVID-19 patients by increasing bed availability and staff, admitting up to 40% of patients in surge capacity beds. Although mortality in this population was high, admission to a surge capacity bed was not associated with increased mortality. Older age, invasive mechanical ventilation, and AKI were identified as the strongest predictors of mortality

Co-infection and ICU-acquired infection in COIVD-19 ICU patients: a secondary analysis of the UNITE-COVID data set

Background: The COVID-19 pandemic presented major challenges for critical care facilities worldwide. Infections which develop alongside or subsequent to viral pneumonitis are a challenge under sporadic and pandemic conditions; however, data have suggested that patterns of these differ between COVID-19 and other viral pneumonitides. This secondary analysis aimed to explore patterns of co-infection and intensive care unit-acquired infections (ICU-AI) and the relationship to use of corticosteroids in a large, international cohort of critically ill COVID-19 patients.Methods: This is a multicenter, international, observational study, including adult patients with PCR-confirmed COVID-19 diagnosis admitted to ICUs at the peak of wave one of COVID-19 (February 15th to May 15th, 2020). Data collected included investigator-assessed co-infection at ICU admission, infection acquired in ICU, infection with multi-drug resistant organisms (MDRO) and antibiotic use. Frequencies were compared by Pearson's Chi-squared and continuous variables by Mann-Whitney U test. Propensity score matching for variables associated with ICU-acquired infection was undertaken using R library MatchIT using the "full" matching method.Results: Data were available from 4994 patients. Bacterial co-infection at admission was detected in 716 patients (14%), whilst 85% of patients received antibiotics at that stage. ICU-AI developed in 2715 (54%). The most common ICU-AI was bacterial pneumonia (44% of infections), whilst 9% of patients developed fungal pneumonia; 25% of infections involved MDRO. Patients developing infections in ICU had greater antimicrobial exposure than those without such infections. Incident density (ICU-AI per 1000 ICU days) was in considerable excess of reports from pre-pandemic surveillance. Corticosteroid use was heterogenous between ICUs. In univariate analysis, 58% of patients receiving corticosteroids and 43% of those not receiving steroids developed ICU-AI. Adjusting for potential confounders in the propensity-matched cohort, 71% of patients receiving corticosteroids developed ICU-AI vs 52% of those not receiving corticosteroids. Duration of corticosteroid therapy was also associated with development of ICU-AI and infection with an MDRO.Conclusions: In patients with severe COVID-19 in the first wave, co-infection at admission to ICU was relatively rare but antibiotic use was in substantial excess to that indication. ICU-AI were common and were significantly associated with use of corticosteroids

A unified model for BAM function that takes into account type Vc secretion and species differences in BAM composition

Transmembrane proteins in the outer membrane of Gram-negative bacteria are almost exclusively β-barrels. They are inserted into the outer membrane by a conserved and essential protein complex called the BAM (for β-barrel assembly machinery). In this commentary, we summarize current research into the mechanism of this protein complex and how it relates to type V secretion. Type V secretion systems are autotransporters that all contain a β-barrel transmembrane domain inserted by BAM. In type Vc systems, this domain is a homotrimer. We argue that none of the current models are sufficient to explain BAM function particularly regarding type Vc secretion. We also find that current models based on the well-studied model system Escherichia coli mostly ignore the pronounced differences in BAM composition between different bacterial species. We propose a more holistic view on how all OMPs, including autotransporters, are incorporated into the lipid bilayer

Early mobilisation in critically ill COVID-19 patients: a subanalysis of the ESICM-initiated UNITE-COVID observational study

Background Early mobilisation (EM) is an intervention that may improve the outcome of critically ill patients. There is limited data on EM in COVID-19 patients and its use during the first pandemic wave. Methods This is a pre-planned subanalysis of the ESICM UNITE-COVID, an international multicenter observational study involving critically ill COVID-19 patients in the ICU between February 15th and May 15th, 2020. We analysed variables associated with the initiation of EM (within 72 h of ICU admission) and explored the impact of EM on mortality, ICU and hospital length of stay, as well as discharge location. Statistical analyses were done using (generalised) linear mixed-effect models and ANOVAs. Results Mobilisation data from 4190 patients from 280 ICUs in 45 countries were analysed. 1114 (26.6%) of these patients received mobilisation within 72 h after ICU admission; 3076 (73.4%) did not. In our analysis of factors associated with EM, mechanical ventilation at admission (OR 0.29; 95% CI 0.25, 0.35; p = 0.001), higher age (OR 0.99; 95% CI 0.98, 1.00; p ≤ 0.001), pre-existing asthma (OR 0.84; 95% CI 0.73, 0.98; p = 0.028), and pre-existing kidney disease (OR 0.84; 95% CI 0.71, 0.99; p = 0.036) were negatively associated with the initiation of EM. EM was associated with a higher chance of being discharged home (OR 1.31; 95% CI 1.08, 1.58; p = 0.007) but was not associated with length of stay in ICU (adj. difference 0.91 days; 95% CI − 0.47, 1.37, p = 0.34) and hospital (adj. difference 1.4 days; 95% CI − 0.62, 2.35, p = 0.24) or mortality (OR 0.88; 95% CI 0.7, 1.09, p = 0.24) when adjusted for covariates. Conclusions Our findings demonstrate that a quarter of COVID-19 patients received EM. There was no association found between EM in COVID-19 patients' ICU and hospital length of stay or mortality. However, EM in COVID-19 patients was associated with increased odds of being discharged home rather than to a care facility. Trial registration ClinicalTrials.gov: NCT04836065 (retrospectively registered April 8th 2021)