Novel Adsorption-Reaction Process for Biomethane Purification/Production and Renewable Energy Storage.

This work proposes an innovative method for the simultaneous upgrading of biogas streams and valorization of the separated CO2, through its conversion to renewable methane. To this end, two sorptive reactors were filled with a layered bed containing a CO2 sorbent (K-promoted hydrotalcite) and a methanation catalyst (Ru/Al2O3). The continuous cyclic operation of the parallel sorptive reactors was carried out by alternately feeding a biogas stream (CO2/CH4 mixture) or H2. The CO2/CH4 mixture is fed to the sorptive reactor during the sorption stage, with CO2 being captured by the sorbent and CH4 exiting as a purified stream (i.e., as biomethane). During the reactive regeneration stage, the inlet stream is switched to pure H2, which reacts with the previously captured CO2 at the methanation catalyst active sites thus producing additional methane. For continuous operation, the two sorptive reactors were operated 180° out of phase and cyclic steady-state could be reached after ca. five cycles. The performance of the cyclic sorptive-reactive unit was assessed through a parametric study to evaluate the influence of different operating conditions, namely, the inlet flow rate and CO2 content during the sorption stage, the hydrogen inlet flow rate during the reactive regeneration stage, the stage duration, and temperature. The inclusion of an inert purge after the reactive regeneration stage was also tested. The performance of the unit was compared to the case of direct hydrogenation of biogas, and conclusions were drawn regarding future optimization, with special attention being given to CH4 productivity and purity. During the parametric study, a compromise between these process indicators, i.e., a productivity of 1.63 molCH4 kgcat -1 h-1 with 70.3% of CH4 purity, was obtained at 350 °C. However, biomethane purities above 80% were easily achieved, though at the expense of methane productivities.

Pyridine as an additive to improve the deposition of continuous electrospun filaments.

Electrospun filaments are leading to a new generation of medical yarns that have the ability to enhance tissue healing through their biophysical cues. We have recently developed a technology to fabricate continuous electrospun filaments by depositing the submicron fibres onto a thin wire. Here we investigate the influence of pyridine on the fibre deposition. We have added pyridine to polydioxanone solutions at concentrations ranging from 0 to 100 ppm, increasing the conductivity of the solutions almost linearly from 0.04 uS/cm to 7 uS/cm. Following electrospinning, this led to deposition length increasing from 1 cm to 14 cm. The samples containing pyridine easily underwent cold drawing. The strength of drawn filaments increased from 0.8 N to 1.5 N and this corresponded to a decrease in fibre diameter, with values dropping from 2.7 µm to 1 µm. Overall, these findings are useful to increase the reliability of the manufacturing process of continuous electrospun filaments and to vary their biophysical properties required for their application as medical yarns such as surgical sutures.

Synthetic sutures: Clinical evaluation and future developments.

Today's sutures are the result of a 4000-year innovation process with regard to their materials and manufacturing techniques, yet little has been done to enhance the therapeutic value of the suture itself. In this review, we explore the historical development, regulatory database and clinical literature of sutures to gain a fuller picture of suture advances to date. First, we examine historical shifts in suture manufacturing companies and review suture regulatory databases to understand the forces driving suture development. Second, we gather the existing clinical evidence of suture efficacy from reviewing the clinical literature and the Food and Drug Administration database in order to identify to what extent sutures have been clinically evaluated and the key clinical areas that would benefit from improved suture materials. Finally, we apply tissue engineering and regenerative medicine design hypotheses to suture materials to identify routes by which bioactive sutures can be designed and passed through regulatory hurdles, to improve surgical outcomes. Our review of the clinical literature revealed that many of the sutures currently in use have been available for decades, yet have never been clinically evaluated. Since suture design and development is industry driven, incremental modifications have allowed for a steady outflow of products while maintaining a safe regulatory position and limiting costs. Until recently, there has been little academic interest in suture development, however the rise of regenerative medicine strategies is shifting the suture paradigm from an inert material, which mechanically approximates tissue, to a bioactive material, which also actively promotes cell-directed repair and a positive healing response. These materials hold significant therapeutic potential, but could be associated with an increased regulatory burden, cost, and clinical evaluation compared with current devices.