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Polyhydroxyalkanoates (PHAs) are biobased and biodegradable polymers that may be considered to replace fossil-based materials. However, their widespread deployment is slowed down because of the high production cost and their low quality. Using methane during the generation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-co-HV) could reduce the production costs, which are usually owed to the carbon source used, and enhance the performance of the material. In fact, the properties of PHB-co-HV make it more suitable than the most common homopolymer, named poly(3-hydroxybutyrate) (PHB), for many applications since it is more flexible, has a wider thermal processing range, a lower crystallinity and permeability to water. In this work, the production of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) was simulated using an innovative process scheme consisting of two bioreactors working in series equipped with a gas recycling unit, which was designed to increase the methane mass transfer from the gas to the liquid. During the first step, a Methylocystis dominated culture was grown on ammonia and methane to reach a high cell concentration; then, the cells were moved to the second bioreactor and subjected to nutrients starvation to favour the metabolic pathway addressed to the accumulation of PHB-co-HV. The effect of the variation of valeric acid concentration (100-400 ppm), which was used as co-substrate, on the fraction of PHB-co-HV stored in the cells and the percentage of 3-hydroxyvalerate (3-HV) was investigated: results showed that the highest the valeric acid concentration, the lower the total polymer content and the higher the HV fraction accumulated.

Thanks to their properties, fossil fuel-based plastics are widely used daily (for industrial, domestic and environmental applications). However, they are not biodegradable, and their end of life is the cause of one of the most dangerous pollution in the world. Plastic, if recovered, can be recycled or used to recover energy, but it is not possible to recover all the tons of waste produced, so some end up in landfills. Therefore all non-recycled and non-collected plastic can take up to a thousand years to degrade. So the scientific idea is to produce biodegradable plastic capable of replacing conventional plastics. One possible solution is the poly(3Hydroxybutyrate) (PHB) of the polyhydroxyalkanoates (PHA) family. PHB is a biopolymer accumulated in intracellular granules, under unfavourable growth conditions, by many prokaryotes and can be extracted with eco-friendly solvents. In particular, the extraction phase consists of the disruption of the cells and the subsequent separation of the biopolymer from the non-biopolymeric material (non-PHB). Currently, solvent extraction is the most used method for PHB recovery because it guarantees a high recovery yield and keeps the characteristics of the extracted biopolymer almost unaltered. In this study, the extraction of PHB with eco-friendly solvents was investigated. Simulations were carried out using 1,2-propylene carbonate as the solvent and acetone as the anti-solvent. Two process schemes were analyzed, without and with the recirculation of solvents (by distillation) and with two different types of biomass (wet and dry). The present work aims to study the final recovery yield in different operating conditions and the influence of PHB solubility on the process. The simulation results confirm the importance of solubility for optimizing the extraction process and underline the problem related to the lack of data in the literature.

Bubble column reactors basically consist of a vertical cylinder filled by a liquid phase in which a gas phase is distributed in the liquid at the column bottom by an appropriate distributor system and moves along the column in the form of bubbles. The aim of a bubble column is to control the rate of mass transfer and reaction between the phases. The liquid phase is modelled as a continuous phase and can be operated in batch mode, or it may move co-currently or counter-currently to the flow of the gas phase. Two-phase and slurry bubble columns are widely used in the chemical- and biochemical industry for carrying out gas-liquid and gas-liquid-solid (catalytic) reaction; in particular, they are used for microalgae growth, aerobic fermentations processes, aerobic treatment of small quantities of highly polluted effluents, as well as oxidation, hydrogenation, chlorination, chemical gas cleaning and, also various biotechnological applications. In this paper, the mass transfer of CH4 to liquid in a bubble column was investigated by means of Computational Fluid Dynamic simulations in a turbulent regime. The effects of the variation of the most significant fluid dynamic parameters, such as inlet gas velocity, on CH4 concentration in the liquid phase and mass transfer from gas to liquid were studied by using COMSOL Multiphysics® Modeling Software. Results point out that the higher inlet velocities, the higher the mass transfer rate, which trend shows a pick after which it reduces to zero when CH4 concentration in the liquid becomes equal to saturation one.

Background Quality of bowel cleansing in hospitalized patients undergoing colonoscopy is often unsatisfactory. No study has investigated the inpatient or outpatient setting as cause of inadequate cleansing. Aims To assess degree of bowel cleansing in inpatients and outpatients and to identify possible predictors of poor bowel preparation in the two populations. Methods Prospective multicentre study on consecutive colonoscopies in 25 regional endoscopy units. Univariate and multivariate analysis with odds ratio estimation were performed. Results Data from 3276 colonoscopies were analyzed (2178 outpatients, 1098 inpatients). Incomplete colonoscopy due to inadequate cleansing was recorded in 369 patients (11.2%). There was no significant difference in bowel cleansing rates between in- and outpatients in both colonic segments. In the overall population, independent predictors of inadequate cleansing both at the level of right and left colon were: male gender (odds ratio, 1.20 [1.02–1.43] and 1.27 [1.05–1.53]), diabetes mellitus (odds ratio, 2.35 [1.68–3.29] and 2.12 [1.47–3.05]), chronic constipation (odds ratio, 1.60 [1.30–1.97] and 1.55 [1.23–1.94]), incomplete purge intake (odds ratio, 2.36 [1.90–2.94] and 2.11 [1.68–2.65]) and a runway time >12 h (odds ratio, 3.36 [2.40–4.72] and 2.53 [1.74–3.67]). Conclusions We found no difference in the rate of inadequate bowel preparation between hospitalized patients and outpatients.

Osseointegrated dental implants have been successfully used over the past several years, allowing functional replacement of missing teeth. Surface properties of titanium dental implants influence bone cell response. Implant topography appears to modulate cell growth and differentiation of osteoblasts thus affecting the bone healing process. Optimal roughness and superficial morphology are still controversial and need to be clearly defined. In the present study we evaluated in vitro the biological behavior of SaOS-2 cells, a human osteoblast-like cell line, cultured on two different titanium surfaces, smooth and sandblasted-acid-etched, by investigating cell morphology, adhesion, proliferation, expression of some bone differentiation markers and extracellular matrix components. Results showed that the surface topography may influence in vitro the phenotypical expression of human osteoblast-like cells. In particular the tested sandblasted-acid-etched titanium surface induced a significantly increased Co I deposition and ±2-²1 receptor expression as compared to the relatively smooth surface, promoting a probable tendency of SaOS-2 cells to shift toward a mature osteoblastic phenotype. It is therefore likely that specific surface properties of sandblasted-acid-etched titanium implants may modulate the biological behavior of osteoblasts during bone tissue healing.