PHASE SHIFTERS BASED ON RF MEMS COPLANAR SHUNT SWITCHES

This paper presents the experimental results obtained on a digital phase shifter based on RF MEMS coplanar shunt switches for radar, beam forming applications. A new design approach is proposed for the design of a digital distributed MEMS phase shifter, and the image parameter representation of two port networks is used to develop an analytical model for this component. Vector network Analyzer measurements have been performed by recording the scattering (S) parameters of the reflected and transmitted signals, and they have been elaborated to get the signal phase shift around the frequency F = 13.7 GHz used for the design. Actually, good performances of the phase shifter have been obtained with respect to the expected ones

Dielectric charging in microwave microelectromechanical Ohmic series and capacitive shunt switches

The charging of the dielectric used for the actuation in microelectromechanical system (MEMS) devices is one of the major failure sources for switches based on this technology. For this reason, a better understanding of such an effect is vital to improve the reliability for both ground and space applications. In this paper, the expected response of MEMS switches to unipolar and bipolar dc actuation voltages has been measured and modeled. Two configurations of MEMS switches, namely, an Ohmic series and a shunt capacitive one designed for microwave applications, have been studied as a test vehicle for charging effects related to the dc actuation pads. The recorded data have been interpreted mainly through the Poole–Frenkel effect due to charge injection when a high voltage is applied to the dielectric layer. Metal-Insulator-Metal sMIMd structures have been also considered as a complementary information for the response of the dielectric material

A low contact-resistance winged-bridge RF-MEMS series switch for wide-band applications

A MEMS ohmic series switch with a winged bridge has been designed, fabricated and tested. Based on the analysis of the various factors affecting the contact resistance of the switch, a new geometry has been adopted for the bridge, which involves the presence of two side wings and an appropriate number of bumps. An accurate electromagnetic analysis has been employed to identify a proper layout to reduce the losses due to bias lines and internal mismatch. In this manner, an on-state return loss better than 25 dB along with an off-state isolation better than 20 dB in the frequency range 0-30 GHz has been demonstrated. In reliability and power handling tests the switches have been actuated up to 108 cycles without any performance degradation and up to 109 cycles with an increase of 0.6 dB in the insertion loss (RF cold switching). Power handling tests have also been performed up to an input power of 5 W, showing a very linear Pout/Pin response and no stiction or failure due to other mechanisms of the MEMS switch

Packaged Single Pole Double Thru (SPDT) and True Time Delay Lines (TTDL) Based on RF MEMS Switches

Packaged MEMS devices for RF applications have been modelled, realized and tested. In particular, RF MEMS single ohmic series switches (SPST) have been obtained on silicon high resistivity substrates and they have been integrated in alumina packages to get single-pole-double-thru (SPDT) and true-time-delayline (TTDL) configurations. As a result, TTDLs for wide band operation, designed for the (6-18) GHz band, have been obtained, with predicted insertion losses less than 2 dB up to 14 GHz for the short path and 3 dB for the long path, and delay times in the order of 0.3-0.4 ns for the short path and 0.5-0.6 ns for the long path. The maximum differential delay time is in the order of 0.2 ns

Single-Pole Double-Thru and True Time Delay Lines in Alumina Packaging Based on RF MEMS Switches in Silicon Technology

Packaged MEMS devices for RF applications have been mod- elled, realized and tested. In particular, RF MEMS single ohmic series switches have been obtained on silicon high resistivity substrates and they have been integrated in alumina packages to get single-pole-double-thru (SPDT) and true-time-delay-line (TTDL) configurations. For this purpose, the individual switches have been considered as the building blocks of more complicated structures, and the alumina substrate has been properly tailored in order to get the best electri-cal performances considering all the technological steps necessary for the final hybrid device. Actually, several parameters and processes have been considered for such an optimization, involving the geometry, the wire bonding and the cover to be used. Test structures with technologically actuated switches have been also manufactured in order to have the best reference result for the proposed structures. After that, the same devices have been packaged for the final test. As a result, TTDLs for wide band operation, specifically designed for the (6–18) GHz band, have been obtained, with insertion losses less than 2 dB up to 14 GHz for the short path and 3 dB for the long path (5 dB for the real device), and delay times in the order of 0.3–0.4 ns for the short path and 0.5–0.6 ns for the long path. The maximum differential delay time is in the order of 0.2 ns

Evaluation of Circulating Endothelial Cells (CECs) As Marker of Endothelial Damage in Allo-Transplanted Patients at High Risk of Hepatic Veno-Occlusive Disease/Sinusoidal Obstruction Syndrome (VOD/SOS): The Cecinvod Study

Sinusoidal obstruction syndrome (SOS), also known as veno-occlusive disease (VOD), is a potentially fatal complication after allogeneic stem cell transplantation (alloSCT). Identifying a predictive biomarker for VOD has been challenging. Since endothelial injury is considered one of the main pathogenic factors for VOD onset, with the CECinVOD prospective study we aimed to evaluate Circulating Endothelial Cells (CEC) in allo-transplanted patients (pts) at higher risk to develop VOD. From October 2020 to November 2022, 150 pts have been enrolled in the CECinVOD study from 11 Italian Bone Marrow Transplantation Units. All pts must be older than 18 years and undergoing myeloablative alloSCT. CECs were detected using the CellSearch system, the FDA-approved immunomagnetic selection approach incorporating ferrofluid nanoparticles (anti CD146) and fluorophore-labelled antibodies (anti CD105, CD45 and DAPI). CEC were defined as CD146+, CD105+, DAPI+ and CD45-. CEC were collected at the following timepoints: before conditioning regimen (T0), at the end of conditioning regimen and before alloSCT (T1), at the time of neutrophils engraftment (T2), and 7-10 days after engraftment (T3). In pts who developed VOD, additional timepoints were collected as follows: at any time of suspected or proven VOD onset (T4), and then weekly during Defibrotide treatment (T5-T8). SOS/VOD was defined according to the 2016 European Group for Blood and Marrow Transplantation criteria. Pts' main characteristics are summarized in Table 1. Six out of 150 pts (4%) developed VOD during the follow up (4 “severe”, and 2 “very severe”). All pts were treated with Defibrotide, obtaining a complete remission in 5 of them, while 1 pt died due to VOD complications. Pts receiving TBI-based regimen were more likely to develop VOD compared to those receiving Treosulfan (10 to 14 g/m2) or Busulfan ev (9.6 to 12.8 mg/kg) (p 0.08). Similarly, higher baseline levels of bilirubin were associated with a higher incidence of VOD (p 0.08). Considering the CECs analysis, 615 samples were evaluated. At the enrollment, CECs levels were not related with any of clinical characteristics analyzed, except for the number of previous treatments. Indeed, those pts with 2 or more previous lines of treatments had higher levels of CECs (OR=0.53; p<0.001). Considering the different timepoints, conditioning regimen and alloSCT result in higher levels of CECs. Thus, CEC were higher at T1 than at T0 (p 0.02), as well as they were even higher at T2 than at T1 (p<0.0001) (Fig.1). Conversely, no significant differences have been observed between T3 and T2. No other clinical characteristic was correlated with CEC counts at the different timepoints. Pts who developed VOD had higher median levels of CEC at all the timepoints analyzed, but this difference has not achieved statistical significance, probably due to the low number of pts in the VOD group. At VOD onset, the pts always had an increase in CEC levels compared with the previous timepoint. After defibrotide treatment, the CEC levels increased in the first week, while they progressively decreased during the VOD treatment (T6 and T7, -50,7% and -71,5%, respectively). Recently, another endothelial activation marker has been considered: the Easix score. We didn't find any relationship between the Easix score at transplant and the VOD onset, even if a trend may be observed. We also investigated whether the CEC levels may be related with Easix score, but we didn't find any relationship at each timepoint. Interestingly, in a subgroup of pts CECs have been observed as a cluster of multiple cells. This data is firstly described in allo-SCT. Its functional significate remains unclear, but we found a relationship between CECs cluster and the number of CECs (p < 0.001). The incidence of VOD in our prospective study was low with respect to the one reported in the literature. This can be explained by the changes in alloSCT from the past (better selection of the pts, lower use of TBI, higher use of reduced intensity regimen) and the retrospective nature of most of the previous reports. We show that CECs can be considered reliable marker of endothelial damage in alloSCT pts, highlighting the impact of previous treatments, the conditioning regimen, and allo-SCT itself. Increased CEC level may be helpful to confirm VOD diagnosis, as well as their monitoring may be useful to evaluate the response to the treatment for VOD

N. 6 Schede di catalogo: n. 7.6 Vescovo Lazzaro, Breviario Armeno; n. 7.7 Copista e miniatore ignoti, Evangeliario armeno; n. 7.8 Officina mesopotamica, Mattoni di fondazione con iscrizione cuneiforme; n. 7.18 Ambito veneziano (?), Lavanda dei piedi; n. 7.19 Ambito Italia centrale (?), San Carlo Borromeo e San Filippo Neri; n. 8.6 Attilio Spaccarelli, Coppa con scene dionisiache

La mostra presenta al pubblico – per la prima volta in modo organico – la raccolta vasta e sorprendente che i coniugi statunitensi George Washington Wurts ed Henriette Tower misero insieme a cavallo fra XIX e XX secolo e donarono poi allo Stato italiano, per l’esattezza al museo di Palazzo Venezia, dove tuttora è conservata. Alla base della mostra vi è comunque anche l’idea di restituire il contesto della raccolta Wurts, ovvero quella particolare forma di collezionismo che tra Ottocento e Novecento si legò così intimamente all’Italia, fino a concretizzarsi spesso nella donazione allo Stato di singole opere o di intere raccolte. La mostra illustra le dinamiche del collezionismo, soprattutto anglo-americano, e del mercato internazionale, sullo sfondo dei radicali cambiamenti vissuti in quegli anni dalla giovane nazione italiana e dalla sua nuova capitale, Roma. La costruzione del Vittoriano, iniziato nel 1885 e inaugurato nel 1911 nell’occasione dell’Esposizione che celebrava il cinquantenario dell’Unità d’Italia, diviene l’emblema che caratterizza la città all’alba del Novecento