Compact and wideband nanoacoustic pass-band filters for future 5G and 6G cellular radios

Over recent years, the surge in mobile communication has deepened global connectivity. With escalating demands for faster data rates, the push for higher carrier frequencies intensifies. The 7-20 GHz range, located between the 5G sub-6 GHz and the mm-wave spectra, provides an excellent trade-off between network capacity and coverage, and constitutes a yet-to-be-explored range for 5G and 6G applications. This work proposes a technological platform able to deliver CMOS-compatible, on-chip multi-frequency, low-loss, wide-band, and compact filters for cellular radios operating in this range by leveraging the micro-to-nano scaling of acoustic electromechanical resonators. The results showcase the first-ever demonstrated low insertion loss bank of 7 nanoacoustic passband filters in the X-band. Most of the filters showcase fractional bandwidths above 3% and sub-dB loss per stage in an extremely compact form factor, enabling the manufacturing of filters and duplexers for the next generation of mobile handsets operating in the X-band and beyond.

Extending the Linearity of AlScN Contour-Mode Resonators Through Acoustic Metamaterials-Based Reflectors

This work describes the implementation of acoustic metamaterials (AMs) made of a forest of rods at the sides of a suspended aluminum scandium nitride (AlScN) contour-mode resonator (CMR) to increase its power handling without causing degradations of its electromechanical performance. The increase in usable anchoring perimeter with respect to conventional CMR designs, enabled by the adoption of two AM-based lateral anchors, permits to achieve improved heat conduction from the resonator's active region to the substrate. Furthermore, thanks to such AM-based lateral anchors' unique acoustic dispersion features, the attained increase of anchored perimeter does not cause any degradations of the CMR's electromechanical performance, even leading to a ~15% improvement in the measured quality factor. Finally, we experimentally show that using our AM-based lateral anchors leads to a more linear CMR's electrical response, which is enabled by a 32% reduction of its Duffing nonlinear coefficient with respect to the corresponding value attained by a conventional CMR design that uses fully etched lateral sides.

Study of the Performance Enhancement of Sc-Doped AlN Super High Frequency Cross-Sectional Lamé Mode Resonators

The increasing use of mobile broadband requires new acoustic filtering technologies that can operate efficiently at frequencies above 6 GHz. Previous research has shown that AlN Super High Frequency (SHF) Cross-Sectional Lamé Mode resonators (CLMRs) can address this challenge, but their performance is limited by the piezoelectric strength of AlN. In this work, we explore the use of substitutional doping of Al in AlN with Sc to enhance the kt2 values of SHF CLMRs. Our results showed that the measured kt2·Qm product of Al72Sc28N CLMRs was four times greater than that of AlN CLMRs operating at the same frequency. Additionally, the measured fractional bandwidth (FWB) of Al72Sc28N 2nd order ladder filters was 4.13%, a fourfold improvement over AlN filters with the same design. We also discuss other aspects of the technology, such as power handling, losses, and spurious mode suppression, and identify potential areas for future research.

[HFR-AEQUILIBRIUM and intradialytic cardiovascular stability: results of the first multicenter study in Lazio]

Intradialytic hypotension (IDH) is a still-frequent and poorly-understood complication of haemodialysis. Haemofiltration has recently been shown to reduce the phenomenon of IDH. HFR-Aequilibrium adds to traditional HFR and is, in practice, a variant comprising endogenous re-infusion of haemodiafiltration with dialysate sodium concentration and ultrafiltration rate profiles elaborated by the ‘Profiler’ plasma sodium biofeedback system, and measurement of plasma sodium via the on-line Natrium sodium sensor.

Urinary composition and lithogenic risk in normal subjects following oligomineral versus bicarbonate-alkaline high calcium mineral water intake

OBJECTIVE

A normal dietary calcium intake to reduce intestinal oxalate absorption is essential to avoid recurrence of calcium oxalate stone formation. It is also important in the prevention of osteopenia in idiopathic hypercalciuria. The calcium content of waters used for hydration may vary from very low to relatively high and is an important factor in prevention or additional risk of stone formation. Therefore, the effect of drinking mineral waters of different calcium concentrations on lithogenic risk factors was studied in normal volunteers.

MATERIALS AND METHODS

Normal subjects were divided into two groups of 11 and 10 individuals each. All followed a prescribed diet with an average calcium content of 800 mg/day. The water intake for hydration consisted of 2 liters of an oligomineral water with a low calcium content, <20 mg/l (group A) or of a bicarbonate alkaline water with a high calcium content, 370 mg/l (group B).

RESULTS

Diuresis increased similarly in both groups; urine calcium increased by about 80 mg/day in group B. A rise in urine oxalate was observed in both groups, along with the increased urine volume. Osmolar excretion increased in group B; urine osmolality decreased significantly only in group A. In spite of the increase in calciuria in group B, Ca/citrate ratio was constant, due to an increase in citrate excretion. Inter-group differences in terms of activity products of calcium phosphate, calculated according with Tiselius's methods, were found. The differences in AP(CaP) index 1 and AP(CaP) index 2 were significant, with higher values in group B, who drank the bicarbonate alkaline mineral water.

CONCLUSIONS

Increased water intake between meals to prevent renal stone recurrence should preferably be achieved with a relatively low calcium water and calcium-rich mineral waters should be avoided.

Surveillance of acute flaccid paralysis in Italy: 1996-1997. AFP Study Group. Acute flaccid paralysis

The last case of poliomyelitis due to transmission of indigenous wild poliovirus occurred in Italy in 1982. To achieve the certification of the eradication of poliomyelitis in Italy, an active surveillance of acute flaccid paralysis (AFP) in the population aged less than 15 years was set up following the World Health Organization (WHO) guidelines. The survey started in 1996 with a pilot study involving 4 out of 21 regions, and was gradually extended to a national level in 1997. The two-year survey identified five patients with diagnosis of vaccine associated paralytic poliomyelitis (VAPP). Polioviruses type 2 and 3 Sabin-like were isolated and characterized in three of them. In the remaining two cases, samples were collected late after the onset of symptoms, and poliovirus could not be isolated. No wild polioviruses were detected during the survey. The rate of non-polio AFP found in Italy in 1997 was 0.61 cases per 100,000, which is lower than the level of 1.0 case per 100,000 considered as acceptable by the WHO. This was mainly due to the delay in organizing the hospital network and starting the active search of AFP cases in the largest and most densely populated regions. Therefore, the overall rate of AFP found in Italy underestimates the global effectiveness of the program, which however will be better evaluated in the next few years. This study is the first systematic attempt to determine the rate of AFP in Italy.

Antigenic and molecular characterization of wild type 1 poliovirus causing outbreaks of poliomyelitis in Albania and neighboring countries in 1996

Mass vaccination has led poliomyelitis to become a rare disease in a large part of the world, including Western Europe. However, in the past 20 years wild polioviruses imported from countries where polio is endemic have been responsible for outbreaks in otherwise polio-free European countries. We report on the characterization of poliovirus isolates from a large outbreak of poliomyelitis that occurred in Albania in 1996 and that also spread to the neighboring countries of Yugoslavia and Greece. The epidemics involved 145 subjects, mostly young adults, and caused persisting paralysis in 87 individuals and 16 deaths. The agent responsible for the outbreak was isolated from 74 patients and was identified as wild type 1 poliovirus by both immunological and molecular methods. Sequence analysis of the genome demonstrated the involvement of a single virus strain throughout the epidemics, and genotyping analysis showed 95% homology of the strain with a wild type 1 poliovirus strain isolated in Pakistan in 1995. Neutralization assays with both human sera and monoclonal antibodies were performed to analyze the antigenic structure of the epidemic strain, suggesting its peculiar antigenic characteristics. The presented data underline the current risks of outbreaks due to imported wild poliovirus and emphasize the need to improve vaccination efforts and also the need to implement surveillance in countries free of indigenous wild poliovirus.

Surveillance of suspected poliomyelitis in Albania, 1980-1995: suggestion of increased risk of vaccine associated poliomyelitis

Surveillance of suspected poliomyelitis cases was conducted in Albania from 1980 through 1995. A total of 93 cases were reported, 11 of which were clinically defined as poliomyelitis cases according to WHO criteria. Poliovirus was isolated from six subjects who were defined as contact vaccine-associated cases. Characterization of isolates by both antigenic and molecular methods showed that, in all cases, the disease was associated with type 2 or 3 polioviruses of vaccine origin with retromutations known to be associated with loss of Sabin attenuated phenotype. Infection occurred despite the fact that all patients had records of previous immunization with oral polio vaccine (OPV), suggesting a failure of vaccination. Four of the five patients from which poliovirus could not be isolated were classified as possible recipient vaccine-associated poliomyelitis on the basis of serology data (presence of antibodies against all three polioviruses) and the temporal association between the latest dose of vaccine received and onset of paralysis. Virological investigation on healthy contacts of the poliomyelitic patients yielded the isolation of a further 12 Sabin-like polio revertant viruses, mostly type 2 and 3. A detailed study of the non-polio acute flaccid paralysis (AFP) cases and their healthy contacts revealed the presence of several enteroviruses, namely Echo, coxsackie and, in three cases type 2 or 3 Sabin-like polioviruses. Overall, these data suggest the absence of circulation of wild-type poliovirus in Albania from 1980 to 1995, before the recent outbreak of poliomyelitis in 1996, and emphasize the need for active surveillance of AFP and laboratory characterization of virus isolates to monitor vaccination efficacy.