Etudes des mécanismes de précipitation de struvite

International audienceLe procédé actuellement retenu pour valoriser le phosphore des lisiers de porcs traités biologiquement est la dissolution du phosphore minéral particulaire par ajout d’acide formique suivi d’une séparation de phase par ajout de polymère et filtration sur tamis de 250 µm puis précipitation des phosphates en struvite (MgNH4PO4•6H2O) par ajout de magnésie (MgO). Le produit de cristallisation est récupéré dans des sacs filtrants de diamètre de coupure 100 µm. Le verrou de ce procédé est l’obtention de cristaux de struvite d’une taille supérieure à 100 µm. Un plan d’expérience en surface de réponse a été élaboré pour optimiser la précipitation de struvite en jar-test en faisant varier les paramètres procédés suivants : l’agitation, la température, l’ajout de MgO en fonction du ratio Mg :Ca et l’ajout d’ammonium en fonction du ratio N :P. Afin de s’affranchir dans un premier temps de la complexité de la matière organique, les essais ont été réalisé en milieu synthétique de composition ionique similaire au lisier de porcs traité biologiquement. La taille des cristaux est particulièrement influencée par la sursaturation et la température. Une faible sursaturation va promouvoir la formation de cristaux d’une taille supérieure à 100µm. La faible sursaturation doit être apportée par la dissolution de la magnésie et non par une moindre quantité d’ammonium. L’ammonium peut en effet se volatiliser en ammoniaque au cours de la réaction et ne doit donc pas être limitant. La température influence la dissolution de la magnésie et donc le pH de la solution, la volatilisation de l’ammoniaque et la solubilité des cristaux de struvite. Il est donc nécessaire de bien maitriser ce paramètre. La composition du solide obtenu est déterminée par spectroscopie Raman et par analyse morphologique. Les tests de calibration de cet appareil ont permis de valider cette méthode d’analyse

Etudes des mécanismes de précipitation de struvite

International audienceLe procédé actuellement retenu pour valoriser le phosphore des lisiers de porcs traités biologiquement est la dissolution du phosphore minéral particulaire par ajout d’acide formique suivi d’une séparation de phase par ajout de polymère et filtration sur tamis de 250 µm puis précipitation des phosphates en struvite (MgNH4PO4•6H2O) par ajout de magnésie (MgO). Le produit de cristallisation est récupéré dans des sacs filtrants de diamètre de coupure 100 µm. Le verrou de ce procédé est l’obtention de cristaux de struvite d’une taille supérieure à 100 µm. Un plan d’expérience en surface de réponse a été élaboré pour optimiser la précipitation de struvite en jar-test en faisant varier les paramètres procédés suivants : l’agitation, la température, l’ajout de MgO en fonction du ratio Mg :Ca et l’ajout d’ammonium en fonction du ratio N :P. Afin de s’affranchir dans un premier temps de la complexité de la matière organique, les essais ont été réalisé en milieu synthétique de composition ionique similaire au lisier de porcs traité biologiquement. La taille des cristaux est particulièrement influencée par la sursaturation et la température. Une faible sursaturation va promouvoir la formation de cristaux d’une taille supérieure à 100µm. La faible sursaturation doit être apportée par la dissolution de la magnésie et non par une moindre quantité d’ammonium. L’ammonium peut en effet se volatiliser en ammoniaque au cours de la réaction et ne doit donc pas être limitant. La température influence la dissolution de la magnésie et donc le pH de la solution, la volatilisation de l’ammoniaque et la solubilité des cristaux de struvite. Il est donc nécessaire de bien maitriser ce paramètre. La composition du solide obtenu est déterminée par spectroscopie Raman et par analyse morphologique. Les tests de calibration de cet appareil ont permis de valider cette méthode d’analyse

Outcomes and Cardiovascular Comorbidities in a Predominantly African-American Population with COVID-19

ABSTRACTImportanceRacial disparities in COVID-19 outcomes have been amplified during this pandemic and reports on outcomes in African-American (AA) populations, known to have higher rates of cardiovascular (CV) comorbidities, remain limited.ObjectiveTo examine prevalence of comorbidities, rates of hospitalization and survival, and incidence of CV manifestations of COVID-19 in a predominantly AA population in south metropolitan Chicago.Design, Setting, ParticipantsThis was an observational cohort study of COVID-19 patients encountered from March 16 to April 16, 2020 at the University of Chicago. Deidentified data were obtained from an institutional data warehouse. Group comparisons and logistic regression modeling based on baseline demographics, clinical characteristics, laboratory and diagnostic testing was performed.ExposuresCOVID-19 was diagnosed by nasopharyngeal swab testing and clinical management was at the discretion of treating physicians.Main Outcomes and MeasuresPrimary outcomes were hospitalization and in-hospital mortality, and secondary outcomes included incident CV manifestations of COVID-19 in the context of overall cardiology service utilization.ResultsDuring the 30 day study period, 1008 patients tested positive for COVID-19 and 689 had available encounter data. Of these, 596 (87%) were AA and 356 (52%) were hospitalized, of which 319 (90%) were AA. Age &gt; 60 years, tobacco use, BMI &gt;40 kg/m2, diabetes mellitus (DM), insulin use, hypertension, chronic kidney disease, coronary artery disease (CAD), and atrial fibrillation (AF) were more common in hospitalized patients. Age &gt; 60 years, tobacco use, CAD, and AF were associated with greater risk of in-hospital mortality along with several elevated initial laboratory markers including troponin, NT-proBNP, blood urea nitrogen, and ferritin. Despite this, cardiac manifestations of COVID-19 were uncommon, coincident with a 69% decrease in cardiology service utilization. For hospitalized patients, median length of stay was 6.2 days (3.4-11.9 days) and mortality was 13%. AA patients were more commonly hospitalized, but without increased mortality.Conclusions and RelevanceIn this AA-predominant experience from south metropolitan Chicago, CV comorbidities and chronic diseases were highly prevalent and associated with increased hospitalization and mortality. Insulin-requiring DM and CKD emerged as novel predictors for hospitalization. Despite the highest rate of comorbidities reported to date, CV manifestations of COVID-19 and mortality were relatively low. The unexpectedly low rate of mortality merits further study.KEY POINTSQuestionsWhat comorbidities are present in African Americans (AA) with COVID-19 and what are the associations with subsequent hospitalization and mortality? What is the incidence of COVID-19-associated cardiac manifestations requiring cardiology service utilization?FindingsIn this observational cohort study that included 689 patients with COVID-19 from south metropolitan Chicago (87% AA), cardiovascular (CV) comorbidities were highly prevalent and more common in those that required hospitalization. In addition to AA, age &gt; 60 years, tobacco use, BMI &gt;40 kg/m2, diabetes mellitus, hypertension, chronic kidney disease, coronary artery disease (CAD), and atrial fibrillation (AF) were more common in those hospitalized. Age &gt; 60 years, tobacco use, CAD, and AF were associated with in-hospital mortality. Despite this, cardiac manifestations of COVID-19 were uncommon, and cardiology service utilization was low. In-hospital mortality was 13%. AA patients were more commonly hospitalized, but without increased mortality.MeaningIn a predominantly AA population with COVID-19 at a major academic hospital located in south metropolitan Chicago, CV comorbidities were common and were risk factors for hospitalization and death. Although the highest rates of comorbidities to date were present in this cohort, mortality was relatively low and merits further study.</jats:sec

Tracheal intubation in critically ill adults with a physiologically difficult airway. An international Delphi study

Purpose: Our study aimed to provide consensus and expert clinical practice statements related to airway management in critically ill adults with a physiologically difficult airway (PDA). Methods: An international Steering Committee involving seven intensivists and one Delphi methodology expert was convened by the Society of Critical Care Anaesthesiologists (SOCCA) Physiologically Difficult Airway Task Force. The committee selected an international panel of 35 expert clinician–researchers with expertise in airway management in critically ill adults. A Delphi process based on an iterative approach was used to obtain the final consensus statements. Results: The Delphi process included seven survey rounds. A stable consensus was achieved for 53 (87%) out of 61 statements. The experts agreed that in addition to pathophysiological conditions, physiological alterations associated with pregnancy and obesity also constitute a physiologically difficult airway. They suggested having an intubation team consisting of at least three healthcare providers including two airway operators, implementing an appropriately designed checklist, and optimizing hemodynamics prior to tracheal intubation. Similarly, the experts agreed on the head elevated laryngoscopic position, routine use of videolaryngoscopy during the first attempt, preoxygenation with non-invasive ventilation, careful mask ventilation during the apneic phase, and attention to cardiorespiratory status for post-intubation care. Conclusion: Using a Delphi method, agreement among a panel of international experts was reached for 53 statements providing guidance to clinicians worldwide on safe tracheal intubation practices in patients with a&nbsp;physiologically difficult airway to help improve patient outcomes. Well-designed studies are needed to assess the effects of these practice statements and address the remaining uncertainties

Photon management for augmented photosynthesis

Microalgae and cyanobacteria are some of nature's finest examples of solar energy conversion systems, effortlessly transforming inorganic carbon into complex molecules through photosynthesis. The efficiency of energy-dense hydrocarbon production by photosynthetic organisms is determined in part by the light collected by the microorganisms. Therefore, optical engineering has the potential to increase the productivity of algae cultivation systems used for industrial-scale biofuel synthesis. Herein, we explore and report emerging and promising material science and engineering innovations for augmenting microalgal photosynthesis