Bacterial cellulose (BC) was produced by Acetobacter xylinum KJ1 in a modified airlift-type bubble column bioreactor, which had a low shear stress and high oxygen transfer rate (k L a). Saccharified food wastes (SFW) were used as the BC production medium due to its low cost. An aeration rate of 1.2 vvm (6 L/min) was tentatively determined as the optimal aeration condition in a 10 L spherical type bubble column bioreactor, by analysis of the oxygen transfer coefficient. When 0.4% agar was added, the BC production reached 5.8 g/L, compared with 5.0 g/L in the culture without the addition of agar. The BC productivity was improved by 10% in the addition of 0.4% agar into the SFW medium. Then, by conversion of a linear velocity of 0.93 cm/sec, from the relationship between the linear velocity and oxygen transfer rate, 1.0 vvm (30 L/min) was determined as an optimal aeration condition in a 50 L spherical type bubble column reactor. Using SFW medium, with the addition of 0.4% agar, and air supplied of 1.0 vvm, 5.6 g/L BC was produced in the 50 L spherical type bubble column bioreactor after 3 days of cultivation, which was similar to that produced in the 10 L bioreactor. In conclusion, the addition of agar, a viscous polysaccharide, into SFW medium is effective for the production of BC, and this scale-up method is very useful for the mass production in a 50 L spherical type bubble column bioreactor by decreasing the shear stress and increasing the k L a.
Rationale:
Multiorgan/system injury was observed in severely infected coronavirus disease 2019 (COVID-19) patients, in addition to viral pneumonia. Recognizing and correcting the key and immediate dysfunctions may reduce mortality.
Patient concerns:
A 66-year-old previously healthy male patient was referred to the isolation ward in Guanggu Branch of Hubei Province Maternity and Childcare Hospital with a high fever and nonproductive cough for twenty days.
Diagnoses:
Diagnosis of severe COVID-19 infectious pneumonia was established by travel history, clinical features, chest imaging, and a positive oropharyngeal swab specimen result for the severe acute respiratory syndrome coronavirus 2 RT-PCR assay.
Interventions:
In addition to standard supportive care, combined inflammatory cytokine depletion therapy (double filtration plasma pheresis and tocilizumab) and convalescent plasma were administered.
Outcomes:
The patient's homeostatic parameters (blood pressure, heart rate, spontaneous respiration, SPO2, and blood gas) recovered, along with the recovery on chest imaging. All the intravenous catheters were removed. Supportive care continued for several days, and the patient was transferred to a non-ICU isolation ward.
Lessons:
It is not safe to draw causal conclusions between cytokine depletion and clinical manifestation improvement with only 1 case, but this is a potential research direction in facing the COVID-19 crisis.
A Pd(OAc)2-catalyzed divergent synthesis of multisubstituted imidazoles and quinazolines from N-allylamidines has been developed. In the presence of oxidant O2 from air and/or a ligand and Pd(OAc)2, imidazoles were obtained. Nonetheless, under microwave (MW) irradiation in a sealed system, quinazolines as major products were produced.
A metal-free catalytic strategy for the facile synthesis of biologically relevant molecular architectures indolizines and imidazopyridines has been developed. The process is promoted by amine and N-heterocyclic carbene (NHC) relay catalysis via Michael addition-[3 + 2] fusion of simple azaarenes and α,β-unsaturated aldehydes. The preparative power is demonstrated in the synthesis of anxiolytic drug saripidem via two simple one-pot operations with overall 45% yield.
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