Optimization of an Impact-Based Frequency Up-Converted Piezoelectric Vibration Energy Harvester for Wearable Devices

This work presents a novel development of the impact-based mechanism for piezoelectric vibration energy harvesters. More precisely, the effect of an impacting mass on a cantilever piezoelectric transducer is studied both in terms of the tip mass value attached to the cantilever and impact position to find an optimal condition for power extraction. At first, the study is carried out by means of parametric analyses at varying tip mass and impact position on a unimorph MEMS cantilever, and a suitable physical interpretation of the associated electromechanical response is given. The effect of multiple impacts is also considered. From the analysis, it emerges that the most effective configuration, in terms of power output, is an impact at the cantilever tip without a tip mass. By changing the value of the tip mass, a sub-optimal impact position along the beam axis can also be identified. Moreover, the effect of a tip mass is deleterious on the power performance, contrary to the well-known case of a resonant energy harvester. A mesoscale prototype with a bimorph transducer is fabricated and tested to validate the computational models. The comparison shows a good agreement between numerical models and the experiments. The proposed approach is promising in the field of consumer electronics, such as wearable devices, in which the impact-based device moves at the frequencies of human movement and is much lower than those of microsystems

Inkjet-Printed Flexible Piezoelectric Sensor for Large Deformation Applications

Next-generation flexible, soft, and stretchable sensors and electronic devices are conquering the technological scene due to their extremely innovative applications. Especially when produced via innovative technologies like additive manufacturing (AM) and/or inkjet printing (IJP), they represent an undeniable strategic asset for Industry 5.0. Within the growing sensor market, they offer advantages in terms of sensitivity and maximum sensing range. In addition, the use of AM/IJP reduces material waste, enhances scalability, and lowers cost production. In the present work, the design and fabrication of a highly flexible inkjet-printed piezoelectric sensor on top of a thin highly flexible polyimide substrate are presented. The silver top and bottom electrodes were inkjet-printed together with a P(VDF-TrFE) active layer with a nominal thickness of 3 μm which is located between them. The experimental results demonstrate that, even in extreme bending conditions and at different bending speeds, the fabricated sensors are able to maintain their performance without mechanical delamination, giving a stable and repeatable output peak-to-peak signal of 850 mV under cyclic bending. The material combination and the IJP-based fabrication technique employed for the first time in this work to produce highly flexible sensors represent a promising novelty in terms of both sensor performance and customization possibilities

Battery modeling for microgrid design: A comparison between lithium-ion and lead acid technologies

Battery energy storage systems are fundamental components in microgrids operations, therefore it is important to adopt models suitable to properly evaluate the performance of these electrical systems. Different methodologies for battery modeling have been developed and tested in this work: (i) Empirical model, in which batteries are described by analytic expressions not based on electrochemical processes; (ii) Equivalent electrical circuit model, in which batteries are described in terms of electrical quantities. These approaches allow to adapt the model to different battery technologies: both the emerging Li-ion and the consolidated lead acid are considered in this paper. The proposed models are implemented in the software Poli. NRG, a Matlab based procedure for microgrid sizing developed by Energy Department of Politecnico di Milano. Simulations are based on a real case study relevant to a microgrid in a rural area: Ngarenanyuki Secondary School in Tanzania. The proposed methodology is used to design a new microgrid based on photovoltaic and energy storage system, comparing the results obtained adopting different modeling approaches and different technologies. Eventually, results are critically analyzed and discussed in order to compare accuracy, computational effort, costs and opportunities

Large mediastinal mass of heterotopic thyroid tissue: a case report and review of literature

Salvatore. Incidental detection of a mediastinal mass in a asymptomatic patient poses a not easy diagnostic problem. For solid masses or cysts, histology or cytology is often necessary. Although substernal extension of a cervical goiter is common, totally intrathoracic primary thyroidal mass is unusual. We describe a rare case of heterotopic accessory mediastinal thyroid in a patient completely asymptomatic both for signs of thyroid dysfunction and mechanical compression. Radiological and hormonal 6 and 12 months follow-up is reported

Beyond Plastic: Oleogel as gel-state biodegradable thermoplastics

The crisis of plastic waste highlights the urgent need for sustainable alternatives. Bioplastics are seen as a potential solution; however, challenges persist as many are still derived from petroleum, lack biodegradability, or fall short in essential properties such as mechanical strength, chemical stability, and ease of processing. This study pioneers the use of ethyl cellulose-based oleogels as bioderived and biodegradable thermoplastics. These groundbreaking bioplastics, obtained from renewable sources and waste oils, represent an environmentally friendly and high-performance alternative to traditional plastics. The bioplastic named OleoPlast is processed at temperatures ranging from 130 to 165 °C, utilizing different biobased oils and adjusting the oil-to-polymer ratio from 10:3.5 to 1:2. This process yields a high level of versatility, offering broad opportunities for customized applications in both research and industry. Remarkable stability under harsh environmental conditions and biocompatibility pave the way for the adoption of such bioplastics in biocomposite structures, food packaging, green electronics, and tissue engineering. Scalability is ensured by compatibility with both large-scale and high-resolution manufacturing processes, including injection and compression molding, computer numeric control (CNC) milling, and 3D fusion deposition modeling. Overall, this work lays the foundation for a new class of gel-state bioplastics, favoring the transition from traditional thermoplastics to sustainable options with vast perspectives of further exploration and customization in both laboratory and industrial environments

Psychiatric emergencies during, after, and before the COVID-19 lockdown: what happened to our patients? A naturalistic observational study.

Background Despite concerns on mental health problems related to lockdowns, recent reports revealed a reduction in psychiatric admissions in Emergency Departments (ED) during the lockdown period compared with the previous year in several countries. Most of the existing studies focused on the first lockdown not considering the different phases of the COVID-19 crisis. The present study aimed to analyze differences in ED admission for psychiatric consultation during three different phases of the COVID-19 health crisis in Italy. Methods Information on ED admission for psychiatric consultations were retrospectively collected at the ED of the Santo Spirito Hospital in Rome (Italy), and compared between the three periods: the lockdown (March-June 2020) and the post-lockdown period (June 2020-June 2021) compared to the pre-lockdown (January 2019-March 2020). Multinomial logistic regression was used to assess the risk of accessing ED for psychiatric consultation before, during, after the lockdown. Results Three thousand and eight hundred seventy-one ED psychiatric consultations were collected. A significant reduction of psychiatric consultations in ED during the lockdown period and the post-lockdown (H 762,45; p < 0.001) was documented. Multinomial logistic regression analysis showed that compared to pre-lockdown during the lockdown and post-lockdown patients were more likely to be men (RRR 1.52; 95% CI 1.10-2.12) and more often diagnosed with non-severe mental illnesses (nSMI) (relative risk ratio [RRR] 1.53, 95% CI 1.10-2.15; and 1.72, 95% CI 1.42-2.08); during the lockdown, patients were also more often diagnosed with alcohol/substance abuse (A&S) (RRR 1.70; 95% CI 1.10-2.65). Conclusions several changes in the clinical characteristics of psychiatric consultations during and after the lockdown emerged from the present study; nSMI and A&S abuse patients were more likely to present at the ED in the lockdown and post-lockdown periods while SMI patients appeared to be less likely. These may inform clinicians and future preventive strategies among community mental health services

Differential responses of zooplankton assemblages to environmental variation in temporary and permanent ponds

Permanent and temporary wetlands in Mediterranean shrublands represent unique repositories of biodiversity, which are increasingly threatened by human-induced habitat loss. The zooplankton of a permanent (P1) and a temporary pond (T35) in the Natural Reserve of Castelporziano, a rare residual stretch of such a shrubland in Central Italy (Latium), was investigated to: (1) expand and deepen knowledge of these endangered freshwater habitats, which represent a crucial component of Mediterranean biodiversity; (2) identify environmental controls regulating the development of zooplankton communities of each environment; and (3) highlight differences in the adaptive responses of the zooplankton community in relation to the different ecological conditions experienced by permanent and temporary habitats. Despite summer desiccation in T35, the two ponds exhibited a relative homogeneity in hydrological and physico-chemical dynamics. Zooplankton assemblages contained 41 total taxa, of which 32 were found in P1 and 28 in T35. Out of the 41 taxa identified, 22 (> 50%) were exclusively present in one of the two ponds. On a yearly basis, the community dynamics of P1 seemed to be conditioned by physical and chemical factors and by hydrological cycle characteristics, while the community of T35 responded to algal blooms, food competition and predator/prey equilibria rather than correlating to abiotic factors. The main differences amongst zooplankton assemblages were observed over short time scales and occurred both within and between seasons, highlighting the role of some structural taxa that dominated the average composition of the community throughout the year, and the importance of "quick-response" taxa in determining the short-term composition and structure variation of pond zooplankton. A year-round cyclic community succession peculiar to each pond is described

Social cognition in people with schizophrenia: A cluster-analytic approach

Background The study aimed to subtype patients with schizophrenia on the basis of social cognition (SC), and to identify cut-offs that best discriminate among subtypes in 809 out-patients recruited in the context of the Italian Network for Research on Psychoses. Method A two-step cluster analysis of The Awareness of Social Inference Test (TASIT), the Facial Emotion Identification Test and Mayer-Salovey-Caruso Emotional Intelligence Test scores was performed. Classification and regression tree analysis was used to identify the cut-offs of variables that best discriminated among clusters. Results We identified three clusters, characterized by unimpaired (42%), impaired (50.4%) and very impaired (7.5%) SC. Three theory-of-mind domains were more important for the cluster definition as compared with emotion perception and emotional intelligence. Patients more able to understand simple sarcasm (14 for TASIT-SS) were very likely to belong to the unimpaired SC cluster. Compared with patients in the impaired SC cluster, those in the very impaired SC cluster performed significantly worse in lie scenes (TASIT-LI &lt;10), but not in simple sarcasm. Moreover, functioning, neurocognition, disorganization and SC had a linear relationship across the three clusters, while positive symptoms were significantly lower in patients with unimpaired SC as compared with patients with impaired and very impaired SC. On the other hand, negative symptoms were highest in patients with impaired levels of SC. Conclusions If replicated, the identification of such subtypes in clinical practice may help in tailoring rehabilitation efforts to the person's strengths to gain more benefit to the person

Insight in cognitive impairment assessed with the Cognitive Assessment Interview in a large sample of patients with schizophrenia

The Cognitive Assessment Interview (CAI) is an interview-based scale measuring cognitive impairment and its impact on functioning in subjects with schizophrenia (SCZ). The present study aimed at assessing, in a large sample of SCZ (n = 601), the agreement between patients and their informants on CAI ratings, to explore patients' insight in their cognitive deficits and its relationships with clinical and functional indices. Agreement between patient- and informant-based ratings was assessed by the Gwet's agreement coefficient. Predictors of insight in cognitive deficits were explored by stepwise multiple regression analyses. Patients reported lower severity of cognitive impairment vs. informants. A substantial to almost perfect agreement was observed between patients' and informants' ratings. Lower insight in cognitive deficits was associated to greater severity of neurocognitive impairment and positive symptoms, lower severity of depressive symptoms, and older age. Worse real-life functioning was associated to lower insight in cognitive deficit, worse neurocognitive performance, and worse functional capacity. Our findings indicate that the CAI is a valid co-primary measure with the interview to patients providing a reliable assessment of their cognitive deficits. In the absence of informants with good knowledge of the subject, the interview to the patient may represent a valid alternative