Istituto Nazionale di Ricerca Metrologica
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Effect of Low Copper Doping on the Optical, Cytocompatible, Antibacterial, and SARS-CoV-2 Trapping Properties of Calcium Phosphate Glasses
Get PDFCalcium phosphate glasses (CPGs) are acquiring great importance in the biomedical field because of their thermomechanical and bioresorbable properties. In this study, optically transparent copper (1 mol %)-doped calcium phosphate glasses (CPGs_Cu) were prepared through the melt-quenching method, and their biocompatibility and antibacterial and antiviral properties were evaluated and compared with undoped CPGs. Biocompatibility was evaluated on murine fibroblast NIH-3T3 cells as a preliminary study of cytocompatibility. The in vitro tests were performed through indirect and direct cytotoxicity analyses by MTT and Alamar Blue assays and supported by electron microscopy observations. Microbiological analyses were performed against the most common Gram-negative and Gram-positive pathogens that cause nosocomial infections: Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, and the methicillin-resistant Staphylococcus aureus strain. In addition, the bioglass samples were exposed to SARS-CoV-2 to assess their effects on viral survival. The obtained results assessed the biocompatibility of both bioglass types and their ability to reduce the viral load and trap the virus. In addition, Cu2+-doped bioglass was found to be antibacterial despite its low content (1 mol %) of copper, making this a promising candidate material for biomedical applications, e.g., surgery probes, drug delivery, and photodynamic therapy
Effect of Yb3+/Er3+ co-doping on the emission properties of fluoroindate glass and glass optical fiber
No full textIn this study, a comprehensive analysis of emission in erbium-doped and erbium and ytterbium co-doped fluoroindate glasses has been presented. The luminescence of the erbium transitions and the effect of ytterbium codoping under 488, 808 and 976 nm laser excitation have been discussed. Optimization of rare-earth (RE) ions doping concentration and the energy transfer processes related to the sensibilization effect in Er3+/Yb3+ codoped fluoroindate glasses focusing on the reciprocal distribution of radiative transitions, energy transfer parameters, and lifetimes have been analyzed. The luminescence consists of several bands in the visible (525, 546 and 660 nm) and the infrared (1550 and 2700 nm) spectral regions that correspond to characteristic radiative energy transitions within the erbium ions. In glasses co-doped with the Er3+/Yb3+ system, an augmentation in the emission intensity was observed in the visible and at 1550 nm, while a decrease was observed in the 2700 nm infrared band. The increase of the Yb3+: 2F5/2 lifetime under 488, 808 and 976 nm excitation showed significant Er3+: 4I11/2 → Yb3+: 2F5/2 back energy transfer. Based on the analysis of the available literature, it can be concluded that energy transfer upconversion and cooperative energy upconversion play a significant role in modulating luminescence intensity values within the examined emission bands. This effect is likely enhanced due to the incorporation in a low phonon energy glass matrix. As a result of the above optimization, a glass optical fiber co-doped with 0.8 YbF3/1.4 ErF3 (in mol%) was drawn and characterized, showing a strong emission at 2.77 μm. The optimized Er3+/Yb3+ co-doped fluoroindate glass and glass optical fiber confirmed their ability to be used in the visible and near-infrared spectral regions as efficient optical fiber sources
Albumin/Mitotane Interaction Affects Drug Activity in Adrenocortical Carcinoma Cells: Smoke and Mirrors on Mitotane Effect with Possible Implications for Patients’ Management
Get PDFMetrological assessment of DC current comparator resistance bridges
Get PDFDirect-current comparator bridges (DCC) are the working horses of primary resistance metrology in the intermediate resistance range. Having a ratio accuracy reaching 10^-7 or better, they allow the realization of resistance scales and the calibration of artifact standard resistors for customers. In this paper we compare the performances of three commercial DCC bridges, by performing measurements on resistors in decadal ratios (1 Ω to 10 kΩ) of very high stability in a thermostated environment. The results show that the three bridges give mutually compatible results within the manufacturer’s specifications, therefore mutually validating the bridges; nevertheless, the readings time series show quite different statistical behavior, with internal correlations, making an evaluation of the Type A measurement uncertainty not trivial
Determination and uncertainty propagation of sensitivity coefficients in rockwell hardness measurements
Get PDFIn the field of hardness measurements, a problem arises when trying to understand how different measurement parameters (speed of the indenter, force, thermal drift, etc.) affect the outcome of the measurement itself. Because the mathematical model defining hardness scales do not consider such factors, the simplest way to include additional influence parameters in the mathematical model is to introduce them linearly via sensitivity coefficients, which are obtained experimentally and thus characterized by uncertainties. Uncertainties of the sensitivity coefficients are in general not considered in the evaluation of the combined standard uncertainty of the hardness measurements. In this paper a general procedure is presented and applied to HRA and HRC measurements
Dynamically Tunable Optical Cavities with Embedded Nematic Liquid Crystalline Networks
Get PDF: Tunable metal-insulator-metal (MIM) Fabry-Pérot (FP) cavities that can dynamically control light enable novel sensing, imaging and display applications. However, the realization of dynamic cavities incorporating stimuli-responsive materials poses a significant engineering challenge. Current approaches rely on refractive index modulation and suffer from low dynamic tunability, high losses, and limited spectral ranges, and require liquid and hazardous materials for operation. To overcome these challenges, a new tuning mechanism employing reversible mechanical adaptations of a polymer network is proposed, and dynamic tuning of optical resonances is demonstrated. Solid-state temperature-responsive optical coatings are developed by preparing a monodomain nematic liquid crystalline network (LCN) and are incorporated between metallic mirrors to form active optical microcavities. LCN microcavities offer large, reversible and highly linear spectral tuning of FP resonances reaching wavelength-shifts up to 40 nm via thermomechanical actuation while featuring outstanding repeatability and precision over more than 100 heating-cooling cycles. This degree of tunability allows for reversible switching between the reflective and the absorbing states of the device over the entire visible and near-infrared spectral regions, reaching large changes in reflectance with modulation efficiency ΔR = 79%
Realisation of an optical pressure standard by a multi-reflection interferometric technique
Get PDFA novel realization of an optical pressure standard, alternative to Fabry-Perot cavity-based techniques, is presented. It is based on the measurement of the refractive index of a gas through an unbalanced homodyne interferometer, designed to have one of its two arms formed by a multi reflection double mirror assembly to establish an unbalance length larger than 6 m in a compact setup.
The paper illustrates the most important steps concerning its realization: the estimate of the pressure-induced deformation of the interferometer, the temperature control at millikelvin level and the measurement in vacuum of the unbalance of the interferometer.
The evaluation of the uncertainty of the realized optical pressure standard currently demonstrated to fulfill the main goal of having the ability to measure pressure with a relative uncertainty of 10 ppm at 100 kPa
Sulle prime armoniche bidimensionali
Get PDFLa scomposizione di un segnale periodico in serie di armoniche e' tecnica ben nota e largamente utilizzata. Ciascun ordine di armonica e' rappresentato da due coefficienti, siano essi quelli di coseno e seno, oppure quelli di un singolo coefficiente complesso. Quando il segnale e' bidimensionale, cioe' e' un vettore, ciascuna componente puo' esser separatamente scomposta in armoniche; cio' porta a quattro coefficienti anziche' due per ciascun ordine di armonica.
Si esamina in questo Rapporto Tecnico soltanto la armonica di primo ordine; essa rappresenta la fondamentale, cioe' la oscillazione sincrona con il periodo esaminato. Nel caso bidimensionale, la rappresentazione parametrica nel piano (x,y) al variare di una variabile indipendente (ad esempio il tempo in un periodo o lo angolo nel giro) e' una ellisse. Questo Rapporto Tecnico esamina nel dettaglio le caratteristiche di tale ellisse, quando questa si riduce ad una circonferenza, quando e' percorsa in verso orario o antiorario, e dimostra che la ellisse e' sempre scomponibile in due circonferenze controrotanti.Decomposing a periodic signal into a series of harmonics is a well-known and widely used technique. Each harmonics order is represented by two coefficients, either those of cosine and sine or those of a single complex coefficient. When the signal is bidimensional, i.e. a vector, each component can be decomposed separately into a series of harmonics. This leads to four coefficients instead of two for each harmonics order. This Technical Report focusses on the harmonics of first order; this represents the fundamental of the signal, that is, the oscillation synchronous with the period of interest. The parametric representation in the plane (x,y) of a bidimensional signal as a function of an independent variable (for instance the time in a period or the angle in a revolution) is an ellipse. This Technical Report studies the details of such ellipse, when it reduces to a circle, when it progresses clockwise or anticlockwise, and proofs that the ellipse can always be decomposed in the sum of two counter-rotating circles
Strain-adjustable reflectivity of polyurethane nanofiber membrane for thermal management applications
Get PDFPassive radiative cooling technologies are highly attractive in pursuing sustainable development. However, current cooling materials are often static, which makes it difficult to cope with the varying needs of all-weather thermal comfort management. Herein, a strategy is designed to obtain flexible thermoplastic polyurethane nanofiber (Es-TPU) membranes via electrospinning, realizing reversible in-situ solvent-free switching between radiative cooling and solar heating through changes in its optical reflectivity by stretching. In its radiative cooling state (0% strain), the Es-TPU membrane shows a high and angular-independent reflectance of 95.6% in the 0.25-2.5 mu m wavelength range and an infrared emissivity of 93.3% in the atmospheric transparency window (8-13 mu m), reaching a temperature drop of 10 degrees C at midday, with a corresponding cooling power of 118.25 W/ m2. The excellent mechanical properties of the Es-TPU membrane allows the continuous adjustment of reflec-tivity by reversibly stretching it, reaching a reflectivity of 61.1% (Delta R = 34.5%) under an elongation strain of 80%, leading to a net temperature increase of 9.5 degrees C above ambient of an absorbing substrate and an equivalent power of 220.34 W m- 2 in this solar heating mode. The strong haze, hydrophobicity and outstanding aging resistance exhibited by this scalable membrane hold promise for achieving uniform illumination with tunable strength and efficient thermal management in practical applications
Evaluation and Correction of B1+-Based Brain Subject-Specific SAR Maps Using Electrical Properties Tomography
Get PDFThe specific absorption rate (SAR) estimates the amount of power absorbed by the tissue and is determined by the electrical conductivity and the E-field. Conductivity can be estimated using Electric Properties Tomography (EPT) but only the E-field component associated with B-1(+) can be deduced from B-1- mapping. Herein, a correction factor was calculated to compensate for the differences between the actual SAR and the one obtained with B-1(+). Numerical simulations were performed for 27 head mod-els at 128 MHz. Ground-truth local-SAR and 10g-SAR (SAR(GT)) were computed using the exact electrical conductivity and the E-field. Estimated local-SAR and 10g-SAR (SAR(EST)) were com-puted using the electrical conductivity obtained with a convection-reaction EPT and the E-field obtained from B-1(+). Correction factors (CFs) were estimated for gray matter, white matter, and cere-brospinal fluid (CSF). A comparison was performed for different levels of signal-to-noise ratios (SNR). Local-SAR/10g-SAR CF was 3.08 +/- 0/06 / 2.11 +/- 0.04 for gray matter, 1.79 +/- 0/05 / 2.06 +/- 0.04 for white matter, and 2.59 +/- 0/05 / 1.95 +/- 0.03 for CSF. SAR(EST) without CF were underestimated (ratio across [infinity -25] SNRs: 0.52 +/- 0.02 for local-SAR; 0.55 +/- 0.01 for 10g-SAR). After cor-rection, SAREST was equivalent to SAR(GT) (ratio across [infinity -25] SNRs: 0.97 +/- 0.02 for local-SAR; 1.06 +/- 0.01 for 10g-SAR). SAR maps based on B-1(+) can be corrected with a correction factor to compensate for potential differences between the actual SAR and the SAR calculated with the E-field derived from B-1(+)