Mixing design for enzymatic hydrolysis of sugarcane bagasse: methodology for selection of impeller configuration.

One of the major process bottlenecks for viable industrial production of second generation ethanol is related with technical-economic difficulties in the hydrolysis step. The development of a methodology to choose the best configuration of impellers towards improving mass transfer and hydrolysis yield together with a low power consumption is important to make the process cost-effective. In this work, four dual impeller configurations (DICs) were evaluated during hydrolysis of sugarcane bagasse (SCB) experiments in a stirred tank reactor (3 L). The systems tested were dual Rushton turbine impellers (DIC1), Rushton and elephant ear (down-pumping) turbines (DIC2), Rushton and elephant ear (up-pumping) turbines (DIC3), and down-pumping and up-pumping elephant ear turbines (DIC4). The experiments were conducted during 96 h, using 10 % (m/v) SCB, pH 4.8, 50 °C, 10 FPU/g biomass, 470 rpm. The mixing time was successfully used as the characteristic parameter to select the best impeller configuration. Rheological parameters were determined using a rotational rheometer, and the power consumptions of the four DICs were on-line measured with a dynamometer. The values obtained for the energetic efficiency (the ratio between the cellulose to glucose conversion and the total energy) showed that the proposed methodology was successful in choosing a suitable configuration of impellers, wherein the DIC4 obtained approximately three times higher energetic efficiency than DIC1. Furthermore a scale-up protocol (factor scale-up 1000) for the enzymatic hydrolysis reactor was proposed.

Power consumption evaluation of different fed-batch strategies for enzymatic hydrolysis of sugarcane bagasse.

The minimization of costs in the distillation step of lignocellulosic ethanol production requires the use of a high solids loading during the enzymatic hydrolysis to obtain a more concentrated glucose liquor. However, this increase in biomass can lead to problems including increased mass and heat transfer resistance, decreased cellulose conversion, and increased apparent viscosity with the associated increase in power consumption. The use of fed-batch operation offers a promising way to circumvent these problems. In this study, one batch and four fed-batch strategies for solids and/or enzyme feeding during the enzymatic hydrolysis of sugarcane bagasse were evaluated. Determinations of glucose concentration, power consumption, and apparent viscosity were made throughout the experiments, and the different strategies were compared in terms of energy efficiency (mass of glucose produced according to the energy consumed). The best energy efficiency was obtained for the strategy in which substrate and enzyme were added simultaneously (0.35 kg(glucose) kWh⁻¹). This value was 52% higher than obtained in batch operation.

Acute Aortic Syndrome in a patient with COVID-19.

The global effects of the COVID-19 pandemic make it of the utmost importance to comprehend its mechanisms and define strategies for the most effective approach possible. The SARS-CoV-2 virus can be responsible for the induction of a hypercoagulable state, which can trigger vascular phenomena of venous etiology, specifically deep venous thrombosis or pulmonary embolism. Arterial thrombotic events associated with COVID-19 have also been described in the medical literature, although less frequently. In this paper the authors report the case of a 66-year-old man who was diagnosed with an Acute Aortic Syndrome, specifically an intramural thrombus on the aortic arch, while he was still infected with the virus. Anticoagulation with low weight molecular heparin was initiated and the patient was admitted at the Internal Medicine ward for a conservative therapeutic approach. The thrombus remained stable on a serial imaging evaluation; therefore, the patient was discharged with oral anticoagulation with subsequent follow-up in the outpatient clinic. This case describes a rare and potentially serious complication of COVID-19, which highlights how broad its clinical spectrum can be, affecting systems other than the pulmonary.

Rhino-Orbital Mucormycosis After COVID-19 Recovery: A Case Report.

The pandemic caused by SARS-CoV-2 remains a health care concern, despite vaccination programs. Mucormycosis, especially rhino-orbital-mucormycosis, has been described as a severe complication of COVID-19. Although it has been described mostly in India and other developing countries, few cases in the western world have also been described. We present a case of rhino-orbito-mucormycosis after recovery from severe COVID-19 in Portugal. A 75-year-old diabetic and obese man presented with right proptosis associated with right eye pain and low vision one month after recovery from severe COVID-19. Considering the most probable etiology for this clinical picture, anti-fungal therapy with liposomal amphotericin B was promptly initiated, followed by endoscopic sinus debridement. However, due to persistent and progressive infection, and after a multidisciplinary revision of the case, orbital exenteration was performed. One year after surgery, the patient is stable, without clinical or imagological signs of relapse of the disease. Although the evolution of the pandemic, along with vaccination programs, led to a lower incidence of severe COVID-19 disease, there are still patients presenting with severe COVID-19, requiring intensive care and at risk for serious complications. This case illustrates the importance of being aware of the development of post-COVID-19 mucormycosis and the need for close surveillance of patients recovering from severe COVID-19. COVID-19 prompt diagnosis and multidisciplinary approach are essential for a timely intervention achieving better survival while minimizing morbidity.

Screening method for Enzyme-based liquefaction of corn stover pellets at high solids.

Liquefaction of high solid loadings of unpretreated corn stover pellets has been demonstrated with rheology of the resulting slurries enabling mixing and movement within biorefinery bioreactors. However, some forms of pelleted stover do not readily liquefy, so it is important to screen out lots of unsuitable pellets before processing is initiated. This work reports a laboratory assay that rapidly assesses whether pellets have the potential for enzyme-based liquefaction at high solids loadings. Twenty-eight pelleted corn stover (harvested at the same time and location) were analyzed using 20 mL enzyme solutions (3 FPU cellulase/ g biomass) at 30 % w/v solids loading. Imaging together with measurement of reducing sugars were performed over 24-hours. Some samples formed concentrated slurries of 300 mg/mL (dry basis) in the small-scale assay, which was later confirmed in an agitated bioreactor. Also, the laboratory assay showed potential for optimizing enzyme formulations that could be employed for slurry formation.

Experimental optimization and techno-economic analysis of bioethanol production by simultaneous saccharification and fermentation process using sugarcane straw.

The present work aims to determine a suitable yield-productivity balance in bioethanol production from hydrothermally pretreated sugarcane straw via pre-saccharification (PS) and simultaneous saccharification and fermentation (SSF). PS experiments were carried out evaluating effects of enzymatic dosage, biomass loading, and PS time. The performance of the whole process (PSSSF) was evaluated based on overall ethanol yield and productivity considering a simultaneous optimization (desirability function) of both variables. The multi-criteria optimization enabled to reach 5.7% w/w ethanol concentration yielding 290 L of ethanol per ton of pretreated sugarcane straw within 45 h of total processing time. Furthermore, a techno-economic analysis was performed under optimized conditions (14.5 FPU/gcellulose, 19.3% w/v biomass loading and 33 h PS time). This process was integrated into a first-generation plant. Although the economic evaluation exhibited a negative performance, a sensitivity analysis indicated that a decrease of 23.3% in operational expenditure would be enough to achieve feasibility.

A kinetic model for hydrothermal pretreatment of sugarcane straw.

This work presents kinetic models of cellulose and hemicellulose extraction during hydrothermal pretreatment of sugarcane straw. Biomass was treated under conditions of 180, 195, and 210°C, using a solid/liquid ratio of 1:10 (w/v). In this study, cellobiose, glucose, formic acid and hydroxymethylfurfural (from cellulosic fraction) and xylose, arabinose, acetic acid, glucuronic acid and furfural (from hemicellulosic fraction) were taken into account in the kinetic parameters determination. The global search algorithm Simulated Annealing was used to fit the models. At 195°C/15min, 85% of hemicellulose and 21% of cellulose removal was reached. For the confidence regions, it was observed that it can be broad, which is coherent with the fact that the parameters are highly correlated. Kinetic models proposed for both cellulosic and hemicellulosic fractions degradation fitted well to the experimental data.

Enzymatic Hydrolysis of Pretreated Sugarcane Straw: Kinetic Study and Semi-Mechanistic Modeling.

Although there are already commercial-scale productions of second generation (2G) ethanol, focusing efforts on process optimization can be of key importance to make the production cost-effective in large scale. In this scenario, mathematical models may be useful in design, scale-up, optimization, and control of bioreactors. For this reason, the aim of this work was to study the kinetics of the enzymatic hydrolysis of cellulose from sugarcane straw. Experiments using hydrothermally pretreated sugarcane (HPS) straw (195 °C, 10 min, 200 rpm) with and without alkaline delignification (4 % NaOH m/v, 30 min, 121 °C) were carried out in shake flasks (50 °C, pH 5.0, 200 rpm). Solid load was varied in a range of 0.8 to 10 % (m/v), in initial velocity and long-term assays. Enzyme concentration (Cellic®CTec2) was varied from 5 to 80 filter paper unit (FPU) gcellulose (-1). It was possible to fit Michaelis-Menten (MM), modified MM, with and without competitive inhibition by glucose, and Chrastil models. Chrastil model and modified MM with inhibition (both suitable for heterogeneous system, with high resistance to internal diffusion) showed more appropriate than pseudo-homogeneous MM model. The fitted models were able to identify key features of the hydrolysis process and can be very useful within the perspective of bioreactors engineering.

Systemic lupus erythaematosus presenting as spontaneous splenic rupture.

Systemic lupus erythaematosus (SLE) is known to involve the reticuloendothelial system, but spontaneous splenic rupture (SSR) in the context of the disease is a very rare complication. We observed a 61-year-old woman with an unremarkable previous medical history who presented with SSR and underwent an emergency splenectomy. The histopathological analysis of the specimen revealed signs of vasculitis. On review of symptoms with the patient, a history of oligoarthralgia, photosensitivity, xerostomia and Raynaud phenomenon was elicited. Laboratory investigations revealed lymphopaenia, mild proteinuria and positive antinuclear and anti-dsDNA antibodies. The patient was started on hydroxychloroquine and the disease has since remained silent. This article addresses the rare association between SLE and SSR.

Extracorporeal membrane oxygenation as bridge-to-decision in acute heart failure due to systemic light-chain amyloidosis.

PATIENT: Female, 58. FINAL DIAGNOSIS: Acute hear failure. SYMPTOMS: Dispnoea • edema • fatigue. MEDICATION: ­ CLINICAL PROCEDURE: Bone marrow biopsy • endomyocardial biopsy • abdominal subcutaneous fat biopsy under ECMO support. SPECIALTY: Cardiology. OBJECTIVE: Rare disease. BACKGROUND: Cardiac amyloidosis results from the amyloid deposition in heart tissue, either in the context of a systemic disease or as a localized form. Several pro-amyloid proteins can produce amyloid deposits in the heart. Each of these amyloidoses has characteristic clinical (cardiac and extracardiac) features, and a specific diagnosis and treatment. CASE REPORT: A 58-year-old woman who presented with acute heart failure and echocardiographic findings strongly suggestive of infiltrative cardiomyopathy needed percutaneous veno-arterial extracorporeal membrane oxygenation (ECMO) as bridge-to-decision. Amyloid deposition was found on endomyocardial and bone marrow biopsies. Bone marrow plasma cell infiltrate with acute renal lesion and hypercalcemia confirmed the diagnosis of multiple myeloma-associated systemic light-chain amyloidosis (AL). Refractory shock with multi-organic failure syndrome persisted and no improvements in left ventricular function and structure were seen. After extensive discussion by a multidisciplinary team, and with the patients' family, she was not considered eligible for high-dose chemotherapy and/or autologous stem cell transplantation, heart transplantation, or sequential heart with autologous stem cell transplantation. The patient died a few hours after ECMO withdrawal. During the 14 days of ECMO support no major bleeding or thrombotic complications occurred. CONCLUSIONS: The clinician must consider a diagnosis of cardiac amyloidosis in patients with heart failure, a restrictive type of cardiomyopathy with ventricular hypertrophy in the absence of valve abnormalities, or uncontrolled arterial hypertension. Although developments in chemotherapy have greatly improved the outcomes in AL amyloidosis, the prognosis of patients with severe cardiac involvement remains very poor. ECMO is potentially a reliable bridge-to-diagnosis and bridge-to-decision in these patients. An experienced ECMO team, careful patient selection, and rigorous management protocols with objective criteria to wean or stop ECMO are needed.

Gitelman or Bartter type 3 syndrome? A case of distal convoluted tubulopathy caused by CLCNKB gene mutation.

A 32-year-old woman with no significant medical history was sent to our consultation due to hypokalaemia (<3.0 mmol/l). Her main complaints were longstanding polyuria and nocturia. Physical examination was normal. Basic investigations showed normal renal function, low serum potassium (2.7 mmol/l) and magnesium (0.79 mmol/l), metabolic alkalosis (pH 7.54; bicarbonate 32.5 mmol/l), elevated urinary potassium (185 mmol/24 h) and normal urinary calcium (246 mg/24 h). Thiazide test revealed blunted response. Chronic vomiting and the abuse of diuretics were excluded. Genetic tests for SLC12A3 gene mutation described in Gitelman syndrome (GS) came negative. CLCNKB gene mutation analysis present in both GS and Bartter (BS) type 3 syndromes was positive. The patient is now being treated with potassium and magnesium oral supplements, ramipril and spironolactone with stable near-normal potassium and magnesium levels. This article presents the case of a patient with hypokalaemia caused by CLCNKB gene mutation hard to categorise as GS or BS type 3.

Effect of the carbon sources on the growth kinetics of Cephalosporium acremonium in the Cephalosporin C production process

The growth phase of Cephalosporium acremonium ATCC 48272 was analized in the batch production process of cephalosporin C. Two media were used: one containing glucose and sucrose as main sources of carbon and energy, and the other containing only glucose. The consumption rate of glucose to form biomass was much higher in medium containing only glucose. The behavior in both media could be satisfactorily explained though simulation of a model which included inibition of glucose comsumption by sucrose in the classical Contois kinetics.