Protocell Communication Through the Eyes of Synthetic Organic Chemists

The bottom-up fabrication of synthetic cells (protocells) from molecules and materials, is a major challenge of modern chemistry. A significant breakthrough has been the engineering of protocells capable of chemical communication using bio- derived molecules and ex situ stabilised cell machineries. These, however, suffer from short shelf-lives, high costs, and require mild aqueous conditions. In this Concept Article we analyse the chemistry at the heart of protocell communication to highlight new opportunities for synthetic chemists in protocell engineer- ing. Specifically, we (i) categorise the main bio-derived chemical communication machineries in enzyme cascades, DNA strand displacement, and gene-mediated communication; (ii) review the chemistries of these signal transduction machineries; and (iii) introduce new types of bio-inspired, fully synthetic artificial enzymes to replace their natural counterparts. Developing protocells that incorporate synthetic analogues of bio-derived signal transduction machineries will improve the robustness, stability, and versatility of protocells, and broaden their applications to highly strategic fields such as photocatalysis and fine chemicals production

Surface Periodic Poling in Lithium Niobate and Lithium Tantalate

Periodic Poling of Lithium Niobate crystals (PPLN) by means of electric field has revealed the best technique for finely tailoring PPLN structures and parameters, which play a central role in many current researches in the field of nonlinear integrated optics. Besides the most studied technique of bulk poling, recently a novel technique where domain inversion occurs just in a surface layer using photoresist or silica masks has been devised and studied. This surface periodic poling (SPP) approach is best suited when light is confined in a thin surface guiding layer or stripe, as in the case of optical waveguide devices. Also, we found that SPP respect to bulk poling offers two orders of magnitude reduction on the scale of periodicity, so that even nanostructures can be obtained provided an high resolution holographic mask writing technique is adopted. We were able to demonstrate 200 nm domain size, and also good compatibility with alpha-phase proton exchange channel waveguide fabrication. Our first experiments on Lithium Tantalate have also shown that the SPP technology appears to be applicable to this crystal (SPPLT), whose properties can allow to overcome limitations such as optical damage or UV absorption still present in PPLN devices. Finally, the issue of SPP compatibility with proton exchange waveguide fabrication will be addresse

Supercritical CO2 drying of food matrices

[EN] This work explore the use of supercritical CO2 drying as alternative technique for the obtainment of pasteurized and high quality dried product. Several tests were conducted on animal, vegetable and fruit matrixes in order to investigate the effectiveness of SC-CO2 drying process at different process conditions. Design of experiment was performed to find the optimal process conditions for vegetable and fruit matrices, using the final water activity of the products as key indicator for the drying efficiency. The inactivation of naturally present microorganisms and inoculated pathogens demonstrated the capability of SC-CO2 drying process to assure a safe product. Moreover, retention of nutrients was compared with conventional drying methods. Results suggest that supercritical drying is a promising alternative technology for food drying.The research leading to these results received funding from the European Community’s Horizon 2020, Call H2020-SFS-2014-2 “Future Food” project and from the Progetto Strategico di Dipartimento SID of the Department of Industrial Engineering (University of Padua). M.T. and G.P. thank Regione Veneto that supported their fellowship through the grant FSE.Zambon, A.; Vizzotto, TM.; Morbiato, G.; Toffoletto, M.; Poloniato, G.; Dall’acqua, S.; De Bernard, M.... (2018). Supercritical CO2 drying of food matrices. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 17-23. https://doi.org/10.4995/IDS2018.2018.7753OCS172

Population-level food availability affects postcopulatory sexual selection dynamics in the guppy

Postcopulatory sexual selection (PCSS), namely sperm competition and cryptic female choice, is typically investigated in benign environments, with a fixed number of partners, which mate at the same time intervals; all conditions that are rarely met in natural populations.Although there is increasing evidence that environmental fluctuations affect sexual selection before mating, whether and to which extent they influence postcopulatory trajectories is still little explored.PCSS was investigated in replicate populations of guppies (Poecilia reticulata) in which males and females mated after maintained for 2 weeks on either restricted (RE) or ad libitum (AL) diet and the paternity of the offspring produced by multiply mated females was assigned using microsatellite markers.Compared to AL fish, RE females (i) had fewer mating partners, but the time interval between the first and the last mating was not affected; (ii) produced broods with a lower variance in male fertilization success (a measure of the opportunity for PCSS); and (iii) produced broods with a paternity bias towards the first mate (reversing the last sperm precedence observed in AL populations), and associated more towards males with higher courtship rate.Our results demonstrate that short-term limitation in food availability significantly influence PCSS by modifying both fertilization success variance and sperm precedence pattern. Environmental variation should therefore become part of the research paradigm to improve our understanding of postcopulatory evolutionary dynamics.Read the free Plain Language Summary for this article on the Journal blog

Numerical analysis of a synchronization phenomenon: Pedestrian-structure interaction

The pedestrian-structure interaction is considered by developing a non-linear double pendulum model, representing the lateral walking of the pedestrian and the horizontal vibration mode of the structure. To understand the synchronization phenomenon, the two oscillators were considered in their phase spaces, and a ring-dynamics approach was applied. As synchronization occurs, pedestrian motion becomes in phase quadrature with a quarter-of-period in advance of the bridge motion: this ensures stability of walking conditions on a moving deck, but causes random cancellation of forces typical of an incoherent crowd. Correspondingly, the lateral force transmitted to the structure increases its value, approaching resonance conditions

On the ground-vehicle induced flows and obstacle interaction for energy harvesting purposes

CFD simulations were conducted with the aim of studying the flow field induced by a road vehicle moving at high speed for energy harvesting purposes. 2D and 3D approaches were used and focus was put on the interaction between the vehicle and an obstacle placed upon the road simulating the shape of a generic harvesting device. 2D RANS simulations have proved that a separated region forms and that a trailed flow exists upon the vehicle which thickness do not exceed 1.1 times the vehicle height. The presence of trailing vehicles was analyzed and the raising of the separation region evaluated. The 3D steady approach showed that 2D modeling did not adequately predict velocity and pressure values even if general trends were captured. Different panel shapes were then compared to assess the effect of placing an obstacle near the moving vehicle. 2D URANS simulations suggested that to overcome an obstacle placed 1 m above the vehicle roof, an energy boost is required, while 3D unsteady calculations showed negligible variations in the vehicle's drag with approaching the obstacle. Furthermore, simulation of the full 3D domain allowed to identify forces time-histories and loading directions acting on a circular cylinder, with definition of an equivalent uniform velocity to characterize the flow impinging on the obstacle. Results showed that force coefficients and equivalent velocity maximums locate in the vehicle nose region, where inviscid-like effects dominates

On the Characterization of Wind Profiles Generated by Road Traffic

This paper analyses the flow field and the power wasted by a heavy-duty truck of modified GTS standard shape (equivalent to GCM class 8). Computational fluid dynamics has been used to analyze truck models at cruise conditions. The selected test matrix includes the study of an isolated truck and of a train of two and three trucks to evidence interaction effects. For each case three different velocities have been considered. The numerical campaign is able to quantify the drag coefficient distribution, the losses generated on the roof by viscous phenomena and the changes in velocity distributions. An in-situ experimental campaign is also settled in the truck lane of Venice highway using ultrasonic anemometers and video cameras set on the same measurement frame. Non-dimensional velocity distributions along the vehicle confirm that the height of the separation bubble is dependent on the number of trucks

Correlation between optical and compositional properties of Ti : LiNbO3 channel optical waveguides

Optical, compositional, and structural characterization of titanium-diffused LiNbO3 channel waveguides has been performed. The refractive index profiles have been reconstructed from near field measurements using a well-adapted mathematical approximation. Crystal lattice deformations have been measured by x-ray diffraction. Titanium concentration profiles measured by secondary ion mass spectrometry have been correlated to the refractive index profiles. The correlation between compositional, structural, and optical properties is discussed