ASSESSMENT OF KINETICS FOR BUTANOL PRODUCTION BY CLOSTRIDIUM ACETOBUTYLICUM

The economic scenario established at the beginning of the third millennium has revived the interest in Acetone-Butanol-Ethanol (ABE) fermentations. Recent developments in molecular techniques applied to solventogenic microrganisms in combination with recent advances in fermentation systems and downstream processing have contributed to improve ABE fermentation processes feasibility and competitiveness. The challenges raised over the last years as regards ABE production may be synthesized in: i) use of renewable resources as substrate; ii) selection of strains characterized by high ABE productivity; iii) development of new fermentation systems; iv) development of new downstream strategies for enhanced solvent recovery. The selection of unconventional substrates is favoured by the ability of clostridia strains to metabolize a wide range of carbohydrates like glucose, lactose, etc...., typically present in wastewater streams e.g. from food industries. Even though clostridia have been proven successful to produce ABE, information about kinetics of substrate conversion, cell growth and butanol production is still lacking. Studies available in literature most typically regard batch tests whose results do not apply easily to continuous processes. The strong interaction between the growth/acidogenesis phase and the solventogenesis phase should be taken into account. The reactor systems investigated for the ABE fermentation belong to the batch and fed-batch typologies. Some attempts are reported in literature regarding continuous fermentation by means of clostridia strains confined in the reactor by immobilization or cell-recycling. The present study reports the preliminary results of a research activity aiming at investigating the feasibility of the ABE production by Clostridium acetobutylicum ATCC824 in a continuous biofilm reactor adopting cheese whey as feedstock. The contribution regards the characterization of the kinetics related to the ABE production process by free C. acetobutylicum ATCC824 adopting as medium lactose solutions, in order to emulate the cheese whey. The conversion process is characterized in terms of cells, acids, solvents, pH, gas composition and total organic compounds as a function of time. Results are worked out to assess the kinetics of the cells growth and of the ABE production. The yields of the carbon source in cells, acids and solvents are also assessed. The investigation is carried out adopting both batch reactors and two continuous reactors. In particular, the continuous reactors are equipped to operate under controlled conversion regimes, acidogenesis or solventogenesis. Tests carried out under batch conditions show that: i) cells growth follows the Monod kinetics for lactose concentration (CL) smaller than 100 g/L; ii) the butanol specific production rate increases linearly with CL; iii) the lactose conversion - measured at the end of the solventogenesis phase - decreases with CL; iv) the selectivity of butanol with respect to total solvents increases with CL and stabilizes at about 72%W for CL larger than 30 g/L. Preliminary tests carried out with the continuous reactor operated under solventogenesis regime show that steady state establishes with respect to cells and metabolites concentration at dilution rate of about 0.04 h-1

High Granularity approaches for effective energy delivery from Photovoltaic Sources

Silicon solar cell technology is a fully mature technology but the need to compete with traditional and other renewable energy sources urges to improve the overall efficiency of a photovoltaic (PV) system by a significant amount. Regardless of the solar panel efficiency, the difference between the nominal performance of a PV system and the energy actually produced is quite high, and it can be quantified in the order of 20%. A loss term, often underestimated, depends on possible failure of the Maximum Power Point Tracking (MPPT) algorithms in the presence of multiple maximum power points in power-voltage characteristic, arising in mismatch conditions. This work proposes High Granularity (HG) approaches in order to improve the PV energy yield: a monitoring strategy, a modeling and a power flux control of the whole PV system, all performed at level of single elementary source (i.e., PV cell or PV panel). An innovative HG sensor infrastructure was developed, and the measurements were exploited to perform an automatic PV system reconfiguration, and to design an information based MPPT. Moreover, the data validated a circuit HG model describing the PV system at single cell level, which also accounts for the electrothermal effect. The model was exploited in an automatic tool which translates an AutoCAD project of a PV plant in an equivalent circuit netlist. Finally, the results were employed to investigate the effectiveness of distributed power conversion – in particular the efficiency of the multilevel cascaded H bridge converter controlled by means of an innovative strategy, which overcomes some issues related to the need of performing a distributed MPPT, was assessed

Accurate Maximum Power Tracking in Photovoltaic Systems Affected by Partial Shading

A maximum power tracking algorithm exploiting operating point information gained on individual solar panels is presented. The proposed algorithm recognizes the presence of multiple local maxima in the power voltage curve of a shaded solar field and evaluates the coordinated of the absolute maximum. The effectiveness of the proposed approach is evidenced by means of circuit level simulation and experimental results. Experiments evidenced that, in comparison with a standard perturb and observe algorithm, we achieve faster convergence in normal operating conditions (when the solar field is uniformly illuminated) and we accurately locate the absolute maximum power point in partial shading conditions, thus avoiding the convergence on local maxima

Synthesis of Oligonucleotide Conjugates and Phosphorylated Nucleotide Analogues: An Improvement to a Solid Phase Synthetic Approach

An improvement to our solid phase strategy to generate pharmacologically interesting molecule libraries is proposed here. The synthesis of newo-chlorophenol-functionalised solid supports with very high loading (0.18–0.22 meq/g for control pore glass (CPG) and 0.25–0.50 meq/g for TG) is reported. To test the efficiency of these supports, we prepared nucleotide and oligonucleotide models, and their coupling yields and the purity of the crude detached materials were comparable to previously available results. These supports allow the facile and high-yield preparation of highly pure phosphodiester and phosphoramidate monoester nucleosides, conjugated oligonucleotides, and other yet unexplored classes of phosphodiester and phosphoramidate molecules

Protein Extraction, Enrichment and MALDI MS and MS/MS Analysis from Bitter Orange Leaves (Citrus aurantium)

: Citrus aurantium is a widespread tree in the Mediterranean area, and it is mainly used as rootstock for other citrus. In the present study, a vacuum infiltration centrifugation procedure, followed by solid phase extraction matrix-assisted laser desorption ionization tandem mass spectrometry (SPE MALDI MS/MS) analysis, was adopted to isolate proteins from leaves. The results of mass spectrometry (MS) profiling, combined with the top-down proteomics approach, allowed the identification of 78 proteins. The bioinformatic databases TargetP, SignalP, ChloroP, WallProtDB, and mGOASVM-Loc were used to predict the subcellular localization of the identified proteins. Among 78 identified proteins, 20 were targeted as secretory pathway proteins and 36 were predicted to be in cellular compartments including cytoplasm, nucleus, and cell membrane. The largest subcellular fraction was the secretory pathway, accounting for 25% of total proteins. Gene Ontology (GO) of Citrus sinensis was used to simplify the functional annotation of the proteins that were identified in the leaves. The Kyoto Encyclopedia of Genes and Genomes (KEGG) showed the enrichment of metabolic pathways including glutathione metabolism and biosynthesis of secondary metabolites, suggesting that the response to a range of environmental factors is the key processes in citrus leaves. Finally, the Lipase GDSL domain-containing protein GDSL esterase/lipase, which is involved in plant development and defense response, was for the first time identified and characterized in Citrus aurantium

Deciphering the Role of Trehalose in Chroococcidiopsis sp. 029’s High-Desiccation Resistance: Sequence Determination, Structural Modelling and Simulative Analysis of the 30S Ribosomal Subunit

Desert strains of the genus Chroococcidiopsis are among the most desiccation-resistant cyanobacteria capable of anhydrobiosis. The accumulation of two sugars, sucrose and trehalose, facilitates the entrance of anhydrobiotes into a reversible state of dormancy by stabilizing cellular components upon water removal. This study aimed to evaluate, at the atomistic level, the role of trehalose in desiccation resistance by using as a model system the 30S ribosomal subunit of the desert cyanobacterium Chroococcidiopsis sp. 029. Molecular dynamic simulations provided atomistic evidence regarding its protective role on the 30S molecular structure. Trehalose forms an enveloping shell around the ribosomal subunit and stabilizes the structures through a network of direct interactions. The simulation confirmed that trehalose actively interacts with the 30S ribosomal subunit and that, by replacing water molecules, it ensures ribosomal structural integrity during desiccation, thus enabling protein synthesis to be carried out upon rehydration

Burden and viral aetiology of influenza-like illness and acute respiratory infection in intensive care units

The purpose of this investigation was to study the viral aetiology of influenza-like illness (ILI) and acute respiratory tract infection (ARTI) among patients requiring intensive care unit admission.A cross-sectional retrospective study was carried out in Sicily over a 4-year period. A total of 233 respiratory samples of patients with ILI/ARTI admitted to intensive care units were molecularly analyzed for the detection of a comprehensive panel of aetiologic agents of viral respiratory infections.About 45% of patients was positive for at least one pathogen. Single aetiology occurred in 75.2% of infected patients, while polymicrobial infection was found in 24.8% of positive subjects. Influenza was the most common aetiologic agent (55.7%), especially among adults. Most of patients with multiple aetiology (76.9%) were adults and elderly. Mortality rates among patients with negative or positive aetiology did not significantly differ (52.4% and 47.6%, respectively).Highly transmissible respiratory pathogens are frequently detected among patients with ILI/ARTI admitted in intensive care units, showing the occurrence of concurrent infections by different viruses. The knowledge of the circulation of several types of microorganisms is of crucial importance in terms of appropriateness of therapies, but also for the implication in prevention strategies and hospital epidemiology

Tips and tricks for robotic pancreatoduodenectomy with superior mesenteric/portal vein resection and reconstruction

Background Open pancreatoduodenectomy with vein resection (OPD-VR) is now standard of care in patients who responded to neoadjuvant therapies. Feasibility of robotic pancreatoduodenectomy (RPD) with vein resection (RPD-VR) was shown, but no study provided a detailed description of the technical challenges associated with this formidable operation. Herein, we describe the trips and tricks for technically successful RPD-VR.Methods The vascular techniques used in RPD-VR were borrowed from OPD-VR, as well as from our experience with robotic transplantation of both kidney and pancreas. Vein resection was classified into 4 types according to the international study group of pancreatic surgery. Each type of vein resection was described in detail and shown in a video.Results Between October 2008 and November 2021, a total of 783 pancreatoduodenectomies were performed, including 233 OPDs-VR (29.7%). RPD was performed in 256 patients (32.6%), and RPDs-VR in 36 patients (4.5% of all pancreatoduodenectomies; 15.4% of all pancreatoduodenectomies with vein resection; 14.0% of all RPDs). In RPD-VR vein resections were: 4 type 1 (11.1%), 10 type 2 (27.8%), 12 type 3 (33.3%) and 10 type 4 (27.8%). Vascular patches used in type 2 resections were made of peritoneum (n = 8), greater saphenous vein (n = 1), and deceased donor aorta (n = 1). Interposition grafts used in type 4 resections were internal left jugular vein (n = 8), venous graft from deceased donor (n = 1) and spiral saphenous vein graft (n = 1). There was one conversion to open surgery (2.8%). Ninety-day mortality was 8.3%. There was one (2.8%) partial vein thrombosis, treated with heparin infusion.Conclusions We have reported 36 technically successful RPDs-VR. We hope that the tips and tricks provided herein can contribute to safer implementation of RPD-VR. Based on our experience, and according to data from the literature, we strongly advise that RPD-VR is performed by expert surgeons at high volume centers

New 23-phosphodiester derivatives of Silibin and DHS: synthesis and preliminary evaluation of antioxidant properties

Silybin is the major flavonolignan of silymarin which is widely used as a natural remedy for the treatment of cirrhosis, chronic hepatitis, and liver diseases associated with alcohol consumption and exposure to environmental toxins. Different studies recently made on the antiradical activity of silybin and DHS have elucidated the functional groups responsible for this activity. The results suggest that the C-23 position could be a site for useful modifications aimed to improve the bioactivity of silybin and/or DHS analogues. Recently we describe an efficient synthetic strategy to obtain a variety of new silybin and 2,3-dehydrosilybin (DHS) derivatives in which the 23-hydroxyl group was converted to a sulfate, phosphodiester, or amine group, using a solution-phase approach. The antioxidant properties of the new compounds were evaluated in a cellular model in vivo and most of them displayed an antioxidant activity comparable or higher to silybin and DHS. These results confirmed the assumption that modifications in position C–23 do not affect the radical scavenging activity of these analogues. With the final goal to expand the repertoire of silybin and DHS C-23 modified, we describe here the synthesis and preliminary evaluation of antioxidant properties of a variety of new silybin and DHS conjugated with different labels through a phosphodiester bond The antioxidative properties of the above-synthesized compounds were determined by free radical scavenging (DPPH) assay