Effect of pelleting on the enzymatic digestibility of corn stover.

Pelleting of lignocellulosic biomass to improve its transportation, storage and handling impacts subsequent processing and conversion. This work reports the role of high moisture pelleting in the enzymatic digestibility of corn stover prior to pretreatment, together with associated substrate characteristics. Pelleting increases the digestibility of unpretreated corn stover, from 8.2 to 15.5% glucan conversion, at 5% solid loading using 1 FPU Cellic® CTec2 per g solids. Compositional analysis indicates that loose and pelleted corn stover have similar non-dissolvable compositions, although their extractives are different. Enzymatic hydrolysis of corn stover after size reduction to normalize particle sizes and removal of extractives confirms that pelleting improves corn stover digestibility. Such differences may be explained by the decreased particle size, improved substrate accessibility, and hydrolysis of cross-linking structures induced by pelleting. These findings are useful for the development of processing schemes for sustainable and efficient use of lignocellulose.

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.

Severity factor kinetic model as a strategic parameter of hydrothermal processing (steam explosion and liquid hot water) for biomass fractionation under biorefinery concept.

Hydrothermal processes are an attractive clean technology and cost-effective engineering platform for biorefineries based in the conversion of biomass to biofuels and high-value bioproducts under the basis of sustainability and circular bioeconomy. The deep and detailed knowledge of the structural changes by the severity of biomasses hydrothermal fractionation is scientifically and technological needed in order to improve processes effectiveness, reactors designs, and industrial application of the multi-scale target compounds obtained by steam explosion and liquid hot water systems. The concept of the severity factor [log10 (Ro)] established>30 years ago, continues to be a useful index that can provide a simple descriptor of the relationship between the operational conditions for biomass fractionation in second generation of biorefineries. This review develops a deep explanation of the hydrothermal severity factor based in lignocellulosic biomass fractionation with emphasis in research advances, pretreatment operations and the applications of severity factor kinetic model.

New strategy for liquefying corn stover pellets.

The movement of solid material into and between unit operations within a biorefinery is a bottleneck in reaching design capacity, with formation of biomass slurries needed to introduce feedstock. Corn stover slurries have been achieved from dilute acid, pretreated materials resulting in slurry concentrations of up to about 150 g/L, above which flowability is compromised. We report a new strategy to liquefy corn stover at higher solids concentration (300 g/L) by initially cooking it with the enzyme mimetic maleic acid at 40 mM and 150 °C. This is followed by 6 h of enzymatic modification at 1 FPU (2.2 mg protein)/g solids, resulting in a yield stress of 171 Pa after 6 h and 58 Pa in 48 h compared to 6806 Pa for untreated stover. Mimetic treatment of corn stover pellets minimizes the inhibitory effect of xylo-oligomers on hydrolytic enzymes. This strategy allows for the delivery of solid lignocellulosic slurry into a pretreatment reactor by pumping, improving operability of a biorefinery.

Vesícula biliar gigante / Giant gallbladder

Se registra el caso de una paciente femenina de 73 años con antecedente de colecistitis crónica, quien al examen físico presentaba una tumoración palpable en hipocondrio derecho que se extendía a fosa ilíaca derecha. La ecografía abdominal mostró aumento del tamaño vesicular que alcanzaba fosa ilíaca derecha con contenido multilitiásico; se confirmó dicho hallazgo con estudio tomográfico. Se realizó laparotomía exploradora con hallazgo operatorio de vesícula gigante de paredes engrosadas, tensa, adherida a órganos circundantes, de dificultosa disección, que requirió punción para drenaje de su contenido. Se efectuó, además, colecistectomía convencional según técnica de Pribram, y se obtuvo una pieza quirúrgica de aproximadamente 15 × 10 cm, con informe de anatomía patológica de colecistitis crónica. En contraste con la presentación habitual de la colecistitis crónica, el caso de referencia obedece a una presentación atípica con una vesícula gigante.

We report the case of a 73-year old female patient with a history of chronic cholecystitis with a palpable mass extending from the right hipochondrium to the right iliac region. An abdominal ultrasound showed an enlarged gallbladder extending to the right iliac region with multiple gallstones confirmed by computed tomography scan. An exploratory laparotmy was performed. A giant gallbladder with thickened walls and presence of adhesions to the neighbor organs that were difficult to remove were found and required drainage. A conventional cholecystectomy was performed using the Pribram's technique. A surgical specimen measuring 15 x 10 cm was sent to the pathologist who made a diagnosis of chronic cholecystitis. This case is an atypical presentation of chronic cholecystitis due to a giant gallbladder.