Istituto Nazionale di Ricerca Metrologica
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Asymmetric CapMix Device Exploiting Functionalized Graphene Oxide and SPEEK Coatings for Improved Energy Harvesting From Salinity Gradients
Get PDFThis work investigated the possibility of using functionalized graphene oxide and sulfonated poly(ether ether ketone) coatings on activated carbons to obtain an asymmetric device suitable for Capacitive Mixing (CapMix) application. Herein the synthesis and fabrication procedures of both materials and electrodes are reported, together with a comprehensive list of electrochemical characterization techniques. The results from the electrochemical characterization are used to design the optimal operational parameters for CapMix experiments involving the materials being studied. A homemade cell is designed and fabricated for CapMix application by polymer micromachining. Electrochemical tests are conducted to optimize the process parameters and the results of this optimization are reported, proving that both the materials and the process parameters play a key role in CapMix. The final device can generate a net power output of 12 mW m−2 by mixing simulated seawater and freshwater. This result paved the way for further application of graphene oxide in the field of renewable energy
Large scale simulations of photosynthetic antenna systems: interplay of cooperativity and disorder
No full textLarge-scale simulations of light-matter interaction in natural photosynthetic antenna complexes containing more than one hundred thousands of chlorophyll molecules, comparable with natural size, have been performed. Photosynthetic antenna complexes present in Green sulfur bacteria and Purple bacteria have been analyzed using a radiative non-Hermitian Hamiltonian, well-known in the field of quantum optics, instead of the widely used dipole-dipole Frenkel Hamiltonian. This approach allows us to study ensembles of emitters beyond the small volume limit (system size much smaller than the absorbed wavelength), where the Frenkel Hamiltonian fails. When analyzed on a large scale, such structures display superradiant states much brighter than their single components. An analysis of the robustness to static disorder and dynamical (thermal) noise shows that exciton coherence in the whole photosynthetic complex is larger than the coherence found in its parts. This provides evidence that the photosynthetic complex as a whole plays a predominant role in sustaining coherences in the system even at room temperature. Our results allow a better understanding of natural photosynthetic antennae and could drive experiments to verify how the response to electromagnetic radiation depends on the size of the photosynthetic antenna
Sonodynamic Treatment Triggers Cancer Cell Killing by Doxorubicin in P‐Glycoprotein‐Mediated Multidrug Resistant Cancer Models
Get PDFDoxorubicin is a widely used chemotherapeutic agent that can be hampered in its efficacy by the occurrence of multidrug resistance (MDR), due to the overexpression of the drug efflux transporter P-glycoprotein. As overcoming MDR still remains an unmet clinical need, this work aims at investigating an innovative strategy. Sonodynamic therapy (SDT) selectively kills cancer cells by combining low-intensity ultrasound (US) with a responsive chemical agent (sonosensitiser) that can be activated to produce reactive oxygen species (ROS). Therefore, the efficacy of SDT, using doxorubicin as sonosensitiser, is studied on human MDR ovarian (A2780/MDR) and colon (HT-29/MDR) cancer cells. The ultrasound exposure of MDR cells pre-incubated with non-cytotoxic concentrations of doxorubicin for 1 h has induced a statistically significant decrease of cell proliferation after 72 h. Interestingly, US has selectively triggered the ROS-mediated cytotoxicity of the doxorubicin entrapped into the cancer cell membrane leading to necrotic cancer cell death by lipid peroxidation. Moving from 2D to 3D HT-29/MDR cell cultures, the ability of SDT to reduce the growth of MDR spheroids by inducing significant necrotic cancer cell death is also confirmed. In conclusion, SDT can have a role in treating MDR tumors by eliciting the ROS-mediated cytotoxicity of doxorubicin
The importance of using sensors with known measurement uncertainty at high-elevation sites: the freeze-thaw cycles
No full textA Low-Cost and Open-Source Magnet Test Station to Improve the Assembly Process of Low-Field Scanner Magnets
No full textDetermining the Permeability of Porous Bioceramic Scaffolds: Significance, Overview of Current Methods and Challenges Ahead
Get PDFThe "architectural suitability" of scaffolds for bone tissue engineering is commonly evaluated by assessing the pore volume and the mean pore size (or pore size distribution, if possible) and comparing these values with the reference ranges of human cancellous bone. However, these two parameters cannot precisely describe the complex architecture of bone scaffolds and just provide a preliminary comparative criterion. Permeability is suggested as a more comprehensive and significant parameter to characterize scaffold architecture and mass transport capability, being also related to bone in-growth and, thus, functional properties. However, assessing the permeability of bioactive ceramics and glass scaffolds is a complex task from both methodological and experimental viewpoints. After providing an overview of the fundamentals about porosity in scaffolds, this review explores the different experimental and numerical approaches used to determine the permeability of porous bioceramics, describing the methodologies used (pump-based, gravity-based, acoustic and computational methods) and highlighting advantages and limitations to overcome (e.g., reliability issues and need for better standardization of the experimental procedures)
Assessment of the INRIM trace water generator and analysis of the uncertainty components down to −100 °C frost-point temperature
Get PDFA low frost-point generator (INRIM 03) able to operate at sub-atmospheric pressure has been recently designed, constructed, and assessed at the Istituto Nazionale di Ricerca Metrologica (INRiM) with the aim of providing the metrological traceability both to instruments developed for the measurement of humidity in atmosphere and to sensors and analysers used in industry for controlling and measuring the amount of water vapour in manufacturing processes. The humidity generator operates in a single temperature single pressure mode, letting the carrier gas (nitrogen) achieve saturation in a single passage through an isothermal saturator. Its working range encompasses a frost-point temperature range from −100 °C to −20 °C, in a pressure range between 200 and 1100 hPa, corresponding to an amount of water fraction range from 13 · 10−9 mol·mol−1 to 6.2 · 10−3 mol·mol−1. In a previous work its performance was assessed in the frost-point temperature range from −75 °C to −20 °C (Cuccaro et al 2018 Meas. Sci. Technol. 29 054002). In this work, a comprehensive set of tests for its characterisation and performance evaluation between −75 °C and −100 °C is presented. A detailed uncertainty analysis in the above temperature range is reported, taking into account all the sources of uncertainty that affect the humid gas generation. An expanded uncertainty (k= 2) of 0.07 °C was found for frost-point temperature measurements between −75 °C and −95 °C, while an expanded uncertainty of 0.26 °C resulted at a frost-point temperature of −100 °C. The relative expanded uncertainty (k = 2) associated with water vapour amount fraction measurements was estimated equal to or better than 1.2% between 35 · 10−9 mol·mol−1 and 6.1 · 10−3 mol·mol−1, increasing up to 6.5% at 13∙10−9 mol·mol−
Polynomial chaos expansion of SAR and temperature increase variability in 3 T MRI due to stochastic input data
Get PDFObjective. Numerical simulations are largely adopted to estimate dosimetric quantities, e.g. specific absorption rate (SAR) and temperature increase, in tissues to assess the patient exposure to the radiofrequency (RF) field generated during magnetic resonance imaging (MRI). Simulations rely on reference anatomical human models and tabulated data of electromagnetic and thermal properties of biological tissues. However, concerns may arise about the applicability of the computed results to any phenotype, introducing a significant degree of freedom in the simulation input data. In addition, simulation input data can be affected by uncertainty in relative positioning of the anatomical model with respect to the RF coil. The objective of this work is the to estimate the variability of SAR and temperature increase at 3 T head MRI due to different sources of variability in input data, with the final aim to associate a global uncertainty to the dosimetric outcomes. Approach. A stochastic approach based on arbitrary Polynomial Chaos Expansion is used to evaluate the effects of several input variability's (anatomy, tissue properties, body position) on dosimetric outputs, referring to head imaging with a 3 T MRI scanner. Main results. It is found that head anatomy is the prevailing source of variability for the considered dosimetric quantities, rather than the variability due to tissue properties and head positioning. From knowledge of the variability of the dosimetric quantities, an uncertainty can be attributed to the results obtained using a generic anatomical head model when SAR and temperature increase values are compared with safety exposure limits. Significance. This work associates a global uncertainty to SAR and temperature increase predictions, to be considered when comparing the numerically evaluated dosimetric quantities with reference exposure limits. The adopted methodology can be extended to other exposure scenarios for MRI safety purposes
Realisation of the triple-point of Argon: comparison between two devices
Get PDFA new cryostat for the realization of the triple-point of the argon (83.8058 K), a defining fixed point of the International Temperature Scale of 1990 (ITS-90), was acquired at Italian National Metrological Institute (INRiM). The new system, manufactured by Fluke, is intended to substitute the current National reference, a model developed at BNM-INM in the 1975. The main difference between the two system is in the way to control the temperature. In the BNM-INM device the temperature is controlled adjusting the pressure of liquid nitrogen bath, in the Fluke system instead, an electrical heater wrapped around the argon cell is used, following cryogenic practice. This paper describes the result of the direct comparison and shows typical phase transitions obtained with the two argon systems. Then, a complete uncertainty budget is evaluated for the new Fluke system and compared with the National standard