A General Process-Based Model for Describing the Metabolic Shift in Microbial Cell Cultures

The metabolic shift between respiration and fermentation at high glucose concentration is a widespread phenomenon in microbial world, and it is relevant for the biotechnological exploitation of microbial cell factories, affecting the achievement of high-cell-densities in bioreactors. Starting from a model already developed for the yeast Saccharomyces cerevisiae, based on the System Dynamics approach, a general process-based model for two prokaryotic species of biotechnological interest, such as Escherichia coli and Bacillus subtilis, is proposed. The model is based on the main assumption that glycolytic intermediates act as central catabolic hub regulating the shift between respiratory and fermentative pathways. Furthermore, the description of a mixed fermentation with secondary by-products, characteristic of bacterial metabolism, is explicitly considered. The model also represents the inhibitory effect on growth and metabolism of self-produced toxic compounds relevant in assessing the late phases of high-cell density culture. Model simulations reproduced data from experiments reported in the literature with different strains of non-recombinant and recombinant E. coli and B. subtilis cultured in both batch and fed-batch reactors. The proposed model, based on simple biological assumptions, is able to describe the main dynamics of two microbial species of relevant biotechnological interest. It demonstrates that a reductionist System Dynamics approach to formulate simplified macro-kinetic models can provide a robust representation of cell growth and accumulation in the medium of fermentation by-products

Mid-Infrared Bloch Surface Waves for biosensing applications

We report on the design, fabrication, and spectroscopic characterization of a 1D Photonic Cristal (1DPC) sustaining Bloch Surface Waves (BSWs) in the mid-infrared. The reported all-dielectric 1DPC structure shows potential for label-free biosensing applications to medical diagnostics

A New Generation of Hydrogen-Fueled Hybrid Propulsion Systems for the Urban Mobility of the Future

The H2-ICE project aims at developing, through numerical simulation, a new generation of hybrid powertrains featuring a hydrogen-fueled Internal Combustion Engine (ICE) suitable for 12 m urban buses in order to provide a reliable and cost-effective solution for the abatement of both CO2 and criteria pollutant emissions. The full exploitation of the potential of such a traction system requires a substantial enhancement of the state of the art since several issues have to be addressed. In particular, the choice of a more suitable fuel injection system and the control of the combustion process are extremely challenging. Firstly, a high-fidelity 3D-CFD model will be exploited to analyze the in-cylinder H2 fuel injection through supersonic flows. Then, after the optimization of the injection and combustion process, a 1D model of the whole engine system will be built and calibrated, allowing the identification of a “sweet spot” in the ultra-lean combustion region, characterized by extremely low NOx emissions and, at the same time, high combustion efficiencies. Moreover, to further enhance the engine efficiency well above 40%, different Waste Heat Recovery (WHR) systems will be carefully scrutinized, including both Organic Rankine Cycle (ORC)-based recovery units as well as electric turbo-compounding. A Selective Catalytic Reduction (SCR) aftertreatment system will be developed to further reduce NOx emissions to near-zero levels. Finally, a dedicated torque-based control strategy for the ICE coupled with the Energy Management Systems (EMSs) of the hybrid powertrain, both optimized by exploiting Vehicle-To-Everything (V2X) connection, allows targeting H2 consumption of 0.1 kg/km. Technologies developed in the H2-ICE project will enhance the know-how necessary to design and build engines and aftertreatment systems for the efficient exploitation of H2 as a fuel, as well as for their integration into hybrid powertrains

Label-free and fluorescence biosensing platform using one dimensional photonic crystal chips

The increasing demand for early detection of diseases drives the efforts to develop more and more sensitive techniques to detect biomarkers in extremely low concentrations. Electromagnetic modes at the surface of one dimensional photonic crystals, usually called Bloch surface waves, were demonstrated to enhance the resolution and constitute an attractive alternative to surface plasmon polariton optical biosensors. We report on the development of Bloch surface wave biochips operating in both label-free and fluorescence modes and demonstrate their use in ovalbumin recognition assays

Study of fluid dynamics at the boundary wall of a microchannel by Bloch surface waves

Understanding how a fluid flows at the boundaries when it is confined at the microscale/nanoscale is crucial for a broad range of engineering and biology applications. We propose an experimental technique based on Bloch surface waves sustained by a one-dimensional photonic crystal to evaluate the speed of the contact line, i.e., the triple junction separating three phases, in the low Reynold’s number regime, and with a nanometric resolution. Here, we report on the experimental characterization of the translatory motion of the contact line that separates two water solutions with a relatively high refractive index mismatch (7.35×10−3) and its slipping over a solid surface. The advantages are the relative simplicity and economy of the experimental configuration

A novel method of iron oxalate production through the valorization of red mud

Bauxite residues known as “Red Mud” (RM) are the principal waste of caustic digestion of bauxite from the Bayer Process, whose costs of disposal are expensive and cover 5 % of the total costs of extraction and processing for aluminum production. Nevertheless, this material can be considered an important source of high-value elements, such as rare earths (REEs) and metals, Fe, Ti, Al and others. In this work, the focus has been on the recovery of iron in the form of the compound Fe(II) oxalate. Four types of acids have been used (HCl, H2SO4, H3PO4, H2C2O4) for iron extraction from RM coming from Montenegro. Hydrochloric acid shows a higher iron extraction capacity, reaching an iron extraction yield in solution of 22.6 %. Sulfuric and phosphoric acid, instead, interacted with RM leading to the formation of sulfonate and phosphate species, inhibiting the leaching ability of individual species. Oxalic acid showed the least amount of iron ions extracted but formed a stable ionic complex in solution, Fe2(C2O4)3∙2 H2O. Starting from this complex it was possible to recover the corresponding salt by a reduction and precipitation process. Through a pre-treatment with HCl and a subsequent treatment with oxalic acid, it was possible to obtain a better yield of iron oxalate. Starting from the laboratory scale, a CHEMCAD plant was conceptualized with a yield higher than 16 % per pass (repeatable 3 times with a global iron yield>50 %) and obtaining iron(II) oxalate dihydrate with purity up to 96%wt. In a holistic view of the problem, the proposed process can operate in parallel with other procedures proposed in the literature for the recovery of other valuable substances from red mud. Data Availability Statement: Not applicable

Enhanced fluorescence detection of interleukin 10 by means of 1d photonic crystals

In the present communication, we report on the exploitation of a Bloch surface wave-enhanced fluorescence scheme for the detection of Interleukin (IL)-10 in a protein-rich buffer mimick-ing a biological sample. IL-10 is a cytokine known for its potent anti-inflammatory and immuno-suppressive effects. It is considered a valuable biomarker for prognostic prediction for both solid tumors and hematological malignancies, and recently, a distinguishing feature of hyperinflammation during severe viral infections. To demonstrate the validity of the technique, we transferred all the reagents and working concentrations used in a gold-standard technique, such as ELISA, to our assay, with a substantial reduction in the execution time and without using any enzymatic amplification during IL-10 recognition. We estimate a limit of detection (LoD) in terms of the concentration of IL-10 in solution of the order of 110 pg/mL (5.8 pM) with a 14% accuracy; in other terms, the presented technique is compatible with the assay range and resolution (1.6 pM) of commercial gold-standard ELISA kits. Moreover, such LoD successfully matches the concentrations reported in literature for IL-10 detection in COVID-19 patients, making the BSW-based sensors a viable solution for rapid and accurate screening of COVID-19-related molecules

Spectroscopic Evidence of Bloch Surface Waves in the Mid Infrared

Bloch Surface Waves are surface electromagnetic waves with very low intrinsic losses, existing in both in-plane and out-of plane polarizations, supported by a one-dimensional photonic crystal with an in-gap defect. We have developed thin-film deposition technology on CaF2 prisms suitable for biosensing applications of BSWs in the mid-infrared. Here we report spectroscopic evidence of BSWs, in perfect agreement with theory, in the wavelength range from 4 to 6 micrometers

Label-free detection of angiogenesis biomarkers using Bloch surface waves on one dimensional photonic crystals

We describe the design and fabrication of biochips based on one dimensional photonic crystals supporting Bloch surface waves for label-free optical biosensing. The planar stacks of the biochips are composed of silica, tantala and titania that were deposited using plasma ion assisted evaporation under high vacuum conditions. The biochip surfaces were functionalized by silanization and appropriate fluidic cells were designed to operate in an automated platform. An angularly resolved optical sensing apparatus was assembled to carry out the sensing studies. The angular operation is obtained by a focused laser beam at a fixed wavelength and detection of the angular reflectance spectrum by means of an array detector. Practical application of the sensor was demonstrated by detecting a specific glycoprotein, Angiopoietin 2, that is involved in angiogenesis and inflammation processes. The protocol used for the label-free detection of Angiopoietin 2 is described and the results of an exemplary assay are given, confirming that an efficient detection can be achieved