Università degli studi Niccolò Cusano
Recent publications
The paper presents a novel pseudo-rigid model for describing the elasto-kinematic behaviour of circular arc flexure hinge subjected to a pure moment. The model is based on the kinematic study of flexure hinge large deflection using second-order motion invariants (polodes and inflection circle), which accurately describes the relative motion between the connected bodies. The proposed pseudo-rigid model has a single degree of freedom. It is an epicyclic arrangement with two rolling without slipping external circles with the same radius and a torsional spring with constant stiffness. Analytical formulas for computing the radius and the location of the two rolling circles and the rotational spring stiffness are deduced. The proposed model has been compared with analytical formulas and structural finite element models in different configurations. The results show very good accordance even for large deflections, confirming the model's effectiveness.
This study is aimed at evaluating through Life Cycle Assessment (LCA) the environmental performances of an integrated system of an existing Water Resources Recovery Facility (WRRF) and a hypothetical hydrothermal carbonization (HTC) plant applied to the generated sewage sludge (SS). Beside the valorisation of the solid product (hydrochar, HC) as a fuel substituting lignite, the possibility to valorize also the liquid fraction (process water, PW) derived by the HTC, by anaerobic digestion to produce biogas, is here proposed and analysed. Additionally, phosphorus recovery from HC, prior its use, by acid leaching with nitric acid is also suggested and evaluated. Thus, four integrated scenarios, based on SS carbonization, are proposed and compared with the current SS treatment, based on composting outside of the WRRF (Benchmark scenario). The proposed scenarios, based on HTC, show improved performances with respect to the benchmark one, for thirteen of sixteen considered impact indicators. For the Climate Change (CC) indicator, the two HTC scenarios are able to reduce the impacts up to – 98%, with respect to the Benchmark. Further, the introduction of anaerobic digestion of PW proves to reduce impacts more than other configurations in eleven on sixteen impact categories. On the contrary, the introduction of phosphorus recovery process negatively affects the values for most of indicators. Thus, possible solutions to improve the integration of this process are outlined (e.g., the use of sulfuric acid instead of nitric one, or the application of a different ratio between solid and acidified solution during acid leaching of HC to recover phosphorus). Graphical abstract
Mixed municipal solid waste (MSW) may be pre-treated in a mechanical–biological treatment (MBT) plant to produce an exiting stream with improved combustible characteristics. The process also produces a second waste stream, which is generally separated on a size basis by industrial sieving equipment. It contains fractions with a high moisture content such as residual food waste, soiled paper and cardboard, and small fragments of other materials. Samples of this stream, collected at an existing plant, were characterized and processed by hydrothermal carbonization (HTC) at laboratory scale, at various temperatures (180, 200 and 220 °C), reaction times (1, 4 and 8 h) and solid to water ratios (0.15 and 0.07). The primary energy balance, on a hypothetical industrial scale, was performed. In brief, the results confirmed that the produced hydrochar was a brittle, hydrophobic, solid carbonaceous product which gave a better combustion performance as the residence time of the HTC process was increased. Moreover, the dewaterability of the carbonized waste was greatly improved when compared to raw, wet samples. The results of the primary energy balance confirmed that the energy contained in the produced hydrochar was higher than the energy consumption for the process itself, under all the HTC working conditions. The energy consumed in the process was in the range of 40–70 % of the energy content of the produced hydrochar.
The centrifugal pendulum dampers are widely used to isolate drivetrain torsional vibrations. The kinematic structure of these devices includes one or more rollers meshing with slots carved on the absorbers and on the rotor. Such a kinematic higher-pair has been termed caged-roller joint. This investigation focuses on the analysis of rollers dynamics influence on modern centrifugal dampers architectures. To specialize the caged-roller joint equations for each kind of pendulum, the absorber motion is described in terms of kinematic invariants. As a result, more refined linear tuning conditions and nonlinear design procedures are disclosed. Finally, numerical tests are carried out to assess the sensitivity of rollers design parameters on the system dynamics. These results show that the rollers inertia effect cannot be neglected in an accurate design, due to the introduction of an undesired detuning of the devices.
Laser-powder bed fusion (L-PBF) processing of 316L stainless steel is allowing the fabrication of high-performance components combined with the highest degree of freedom in defining the geometry to be produced. However, similarly to other recent technologies, the manufacturing of L-PBF requires a proper tuning of the process parameters, which vary with the application for which the manufactured component is intended. Therefore, it is fundamental to characterize the mechanical performance of functional products, especially for parts designed to resist to time-varying loading conditions. In this framework, the present work presents results about the back stress hardening and strengthening effect induced in L-PBF-fabricated samples for various combinations of building orientation and process parameters. At first, the work presents the response of the L-PBFmanufactured samples to a monotonic tensile load. Then, it follows the presentation of their hardening and strengthening back stress response to a repetitive progressive loading condition. Quasi-static tensile tests show that L-PBF specimens have lower elastic modulus but higher ultimate and yield strength than the original bulk material, whereby the results evidence a strong anisotropy related to the building orientation, especially for the ultimate tensile strain. Porosity and building orientation are found to strongly affect both the elastic and the plastic response of the samples, with a back stress hardening effect which is much less pronounced when compared to the bulk material, while the opposite occurs for the back stress strengthening. As a result, the plastic strain, therefore the ductility, and the yield strength are increased, while the stiffness is reduced.
Viral infections are a major cause of severe, fatal diseases worldwide. Recently, these infections have increased due to demanding contextual circumstances, such as environmental changes, increased migration of people and product distribution, rapid demographic changes, and outbreaks of novel viruses, including the COVID-19 outbreak. Internal variables that influence viral immunity have received attention along with these external causes to avert such novel viral outbreaks. The gastrointestinal microbiome (GIM), particularly the present probiotics, plays a vital role in the host immune system by mediating host protective immunity and acting as an immune regulator. Bacteriocins possess numerous health benefits and exhibit antagonistic activity against enteric pathogens and immunobiotics, thereby inhibiting viral infections. Moreover, disrupting the homeostasis of the GIM/host immune system negatively affects viral immunity. The interactions between bacteriocins and infectious viruses, particularly in COVID-19, through improved host immunity and physiology are complex and have not yet been studied, although several studies have proven that bacteriocins influence the outcomes of viral infections. However, the complex transmission to the affected sites and siRNA defense against nuclease digestion lead to challenging clinical trials. Additionally, bacteriocins are well known for their biofunctional properties and underlying mechanisms in the treatment of bacterial and fungal infections. However, few studies have shown the role of probiotics-derived bacteriocin against viral infections. Thus, based on the results of the previous studies, this review lays out a road map for future studies on bacteriocins for treating viral infections.
This paper describes a compact electronic system employing a synchronous demodulation measurement method for the acquisition of pulsed-current signals. The fabricated prototype shows superior performance in terms of signal-to-noise ratio in comparison to conventional instrumentation performing free-running measurements, especially when extremely narrow pulses are concerned. It shows a reading error around 0.1% independently of the signal duty cycle (D) in the investigated D = 10−4–10−3 range. Conversely, high-precision electrometers display reading errors as high as 30% for a D = 10−4, which reduces to less than 1% only for D > 3 × 10−3. Field tests demonstrate that the developed front-end/readout electronics is particularly effective when coupled to dosimeters irradiated with the X-rays sourced by a medical linear accelerator. Therefore, it may surely be exploited for the real-time monitoring of the dosimeter output current, as required in modern radiotherapy techniques employing ultra-narrow pulses of high-energy photons or nuclear particles.
This study investigates experimentally and numerically the effects of sills with different geometric specifications at various positions on the hydraulic characteristics of flow through sluice gates. The simulation results showed that the RNG turbulence model’s statistical indicators yield high accuracy compared to the k-ε, k-ω, and LES turbulence models. The discharge coefficient (Cd) has an inverse relationship with gate opening. Regarding sill state, the discharge coefficient is higher than no-sill state. In the case of non-suppressed sills, the Cd decreases compared to the smaller openings as the opening of the gate changes. The results showed that the Cd with a sill in the tangent position upstream of the gate is higher than the downstream tangent and below situations. Increasing the sill length leads to an increase in flow shear stress and consequently a decrease in Cd. The Cd of gates with different sill thicknesses is always higher than the no-sill state, but due to the constant ratio of the fluid depth above the sill to the gate opening, the Cd increases to a certain extent and then decreases with increasing sill thickness.
Background The oxygen uptake efficiency slope (OUES) is considered a reliable indicator of cardiorespiratory fitness in young and clinical populations who cannot achieve maximal effort during a graded exercise test. However, OUES accuracy depends on the data points used for its calculation and it is still not clear if the submaximal OUES can accurately assess CRF in healthy young males. Objective We investigated the association between peak oxygen uptake and peak and submaximal OUES, and the agreement between submaximal OUES and peak OUES in male adolescents and young adults. Methods In this cross-sectional, observational study, fifty normal weight healthy participants (age 14–22 years, peak oxygen uptake 43.8 ± 7.3 mL·min ⁻¹ ·kg ⁻¹ ) performed a graded exercise test on a cycle ergometer and pulmonary gas exchange was assessed using breath-by-breath analysis. Peak oxygen uptake, and oxygen consumption at the aerobic and at the anaerobic threshold were determined as the 30-s average of the oxygen consumption values. Peak OUES (up to peak) and submaximal OUES (up to the aerobic and anaerobic thresholds) were calculated from the logarithmic relation between oxygen consumption and pulmonary ventilation. Results Very strong correlations were observed between peak oxygen uptake and peak OUES ( r = 0.80–0.88) while fair-to-very strong correlations were observed between the peak oxygen uptake and the two submaximal OUES ( r = 0.32–0.81). The level of agreement between peak OUES and OUES up to the anaerobic threshold ( r = 0.89–0.93; Typical percentage error 6%; Intraclass correlation coefficient = 0.89–0.93) was greater than the one between the peak oxygen uptake with OUES up to the aerobic threshold ( r = 0.39–0.56; Typical percentage error 15%; Intraclass correlation coefficient = 0.38–0.56). Conclusions . The peak OUES is a better indicator of aerobic fitness than the OUES up to the anaerobic threshold in healthy, young males. The OUES up to the anaerobic threshold is a valid alternative to peak OUES.
In this paper we study the reduced and unreduced Lq,p-cohomology groups of oriented manifolds of bounded geometry and their behavior under uniform maps. A uniform map is a uniformly continuous map such that the diameter of the preimage of a subset is bounded in terms of the diameter of the subset itself. In general, for each p,q∈[1,+∞), the pullback map along a uniform map does not induce a morphism between the spaces of p-integrable forms or even in Lq,p-cohomology. Then our goal is to introduce, for each p in [1,+∞) and for each uniform map f between manifolds of bounded geometry, an Lp-bounded operator Tf, such that it does induce in a functorial way the appropriate morphism in reduced and unreduced Lq,p-cohomology.
Fabrication of dental restorations made of zirconia-based biomaterials with enhanced mechanical and tribological properties together with customized surface topography and microstructure for promoting enamel adhesion and cell proliferation while hindering bacterial spreading is a very challenging task to accomplish through conventional machining operations. In fact, traditional milling processes of sintered ceramics are typically labor-intensive, therefore expensive and time-consuming, and these aspects can be further exasperated when microsized features are required. On the other hand, unconventional techniques such as laser milling can represent a suitable solution to produce miniaturized individualized structures on advanced ceramics since it is a non-contact thermal process that ensures the elimination of cutting forces and allows hard and brittle materials to be machined without the need for special equipment which requires high investments and long processing times. In this context, this study aims to investigate the capability of a nanosecond pulsed fiber laser to machine samples made of yttria-stabilized zirconia through a systematic experimental approach in order to identify the most suitable process operational parameters combinations that ensure the obtainment of specific surface topographies while minimizing the machining time. The milling process is carried out by using a 30 W Q-switched Yb:YAG fiber laser by controlling laser beam scan speed, scan strategy and hatch distance and following a multi-level factorial design-based experimentation. The adoption of the laser technology to machine yttria-stabilized zirconia results in a high-repeatable, accurate and time-saving process allowing easy control of the process outcomes.
The use of 3D models in planning and simulation of surgical activity is becoming more and more an effective tool to acquire information crucial for formulating a strategy in the treatment of aneurysms, improving the safety and the success of the surgical procedure. These preoperative activities have been made possible by stereolithography printer (SLA) technology that can replicate geometries customized on patients' anatomy. This can be obtained from the DICOM data of the patient that are converted to CAD and processed by a 3D printer. In a previous study by the authors, 3D models of aneurysms were produced by SLA using a complex and opaque resin. The present work constitutes a progression on this pathway, focused on fabricating hollow models. Two different SLA printers were used. The first one was to process hollow geometries made of a rigid translucent resin (epoxy/acrylic mixture). The second machine returned hollow geometries by using a flexible clear acrylic resin. Both rigid and deformable models were characterized and compared. A dimensional evaluation of recesses in the aneurysm cavity and surrounding vascular structures was conducted by insertion of a calipered tool, and the models were validated by surgeons. The newly developed model resulted of interest in both pre-operatory activities as well as training and teaching.
Ten good outcome and ten poor outcome psychotherapy cases were compared to investigate whether or not the temporal stability and flexibility of their process variables can predict their outcomes. Each participant was monitored daily using the Therapy Process Questionnaire (TPQ), which has 43 items and seven sub-scales, and responses over time were analyzed in terms of correlation robustness and correlation variability across the TPQ sub-scales. “Correlation robustness” and “correlation variability” are two basic characteristics of any correlation matrix: the first is calculated as the sum of the absolute values of Pearson correlation coefficients, the second as the standard deviation of Pearson correlation coefficients. The results demonstrated that the patients within the poor outcome group had lower values on both variables, suggesting lower stability and flexibility. Furthermore, a higher number of cycles of increase and decrease in correlation robustness and variability of the TPQ sub-scales was observed within good outcome psychotherapies, suggesting that, these cycles can be considered as process-markers of good-outcomes. These results provide support for the validity of these quantitative process-parameters, correlation robustness and variability, in predicting psychotherapeutic outcomes. Moreover, the results lend support to the common clinical experience of alternating periods of flexibility and integration being beneficial to good psychotherapeutic processes.
As traditional fossil energy sources are continuously diminishing, the demand for optimising output from renewable energy sources is gaining particular importance. Among these, solar energy is certainly one of the most prominent technology and it is widely used in a variety of applications, either concerning electricity and heat production. Nonetheless, the global efficiency of solar systems still has to be largely improved, reducing at the same time generation costs, in order to make solar an even more relevant source of clean energy. In modern photovoltaic, concentrated photovoltaic as well as concentrated solar power plants, the net output can be increased through solar tracking solutions aiming at the optimal positioning of the solar panels/mirrors on a daily and seasonal basis. This typically requires electromechanical motors, which are designed to align the incident solar radiation with the optical axis, thus enhancing the overall energy conversion efficiency but draining at the same time up to 1–2% of the theoretically achievable net power output. Furthermore, to increase energy dispatchability concentrated solar power plants usually incorporates thermal energy storage units, which can be of the sensible-heat or latent-heat storage type. The latter imply phase transition of the storage material which, in turn, can generate up to 20% volumetric expansion for a solid-to-liquid transition. Although generally assumed as an undesired side effect, such expansion can represent an opportunity to extract mechanical work and thus increase the overall efficiency of the solar system. The main objective of this study is to provide an initial quantitative assessment of the passive tracking potential related to the phase-change induced expansion of thermal storage media in concentrated solar power plants. To this aim, a solar-integrated waste-to-heat steam power plant, rated at 15 MWe, has been taken as a reference and a coupled finite-difference/finite-volume numerical model of the latent-heat thermal energy storage unit of the plant has been developed. The model takes input data from the power plant operating conditions and is able to retrieve time-resolved temperature and volumetric density changes of the thermal storage media. Results from the numerical model shows that passive solar tracking is achievable for a fraction of the heliostat field that ranges from 10% to 100%, depending on the season and operating pressure of the tracking system. In terms of electrical power savings, this is up to 2% of the net power output of the reference plant, thus representing a promising basis for further investigations on the applicability of the proposed novel integrated passive solar tracking concept.
We present in this article the implementation of a cellular automaton to predict light emission from an InGaN/GaN quantum dot-based matrix. In particular, we determined the characteristic of the matrix in order to obtain white light in quantum-dot based LEDs. We created a cellular automaton that performs the requested task through a number of steps that increases linearly with the size of the matrix, thus ensuring a valid tool for large-sized quantum dot matrices.
Objectives Open surgery is a reliable choice for congenital subglottic stenosis, that represents the third most common congenital anomaly of the larynx. One of the procedures performed is anterior laryngotracheal reconstruction (LTR) with anterior rib graft. The objective of this preliminary study was to evaluate the potential of 3D printing technology for the realization of laryngo-tracheal scaffold in Polycaprolactone (PCL) implanted in vivo in ovine animal model. Methods A 3D computer model of a laryngeal graft and a tracheal graft was designed and printed with PCL through 3D additive manufacturing technology. The scaffolds were seeded with autologous mesenchymal stem cells and cultured in vitro for up to 14 days. Anterior graft LTR with 3D printed scaffolds was performed on 5 sheep. The animals underwent endoscopic examinations at the first, 3rd, 6th, and 12th weeks after surgery and before sacrifice. The integration of the material was evaluated by the pathologist. Results Two animals showed a favourable postoperative course and were sacrificed at 6 months postoperatively. In these cases, we observed endoscopically a complete integration of the cellularized PCL scaffold into the peri-implant tissues, and the pathologist found the growth of respiratory epithelium on the scaffold's inner surface. Other two animals showed a difficult post-operative recovery characterized by respiratory distress resulting in early sacrifice on postoperative days 31 and 33. In these animals we found a poor integration of the grafts into the tracheal structure, and a better integration of the laryngeal scaffold. The last animal developed a wound abscess and was sacrificed 80 days after surgery. We observed, in this case, a poor scaffold integration and an acute inflammatory reaction. Conclusions From the preliminary data obtained we found that the excessive stiffness of the material, along with the anatomical features of the sheep, is a major limitation of this study. It will be necessary in the future to create a new biocompatible, more flexible and elastic graft, to achieve greater integration into surrounding tissues. Bioconstructed grafts could simplify surgery for the treatment of laryngo-tracheal stenosis, particularly in the treatment of long tracheal stenoses, which have, at the moment, very complex surgical options. Level of evidence NA.
Black diamond is an emerging material for solar applications. The femtosecond laser surface treatment of pristine transparent diamond allows the solar absorptance to be increased to values greater than 90% from semi-transparency conditions. In addition, the defects introduced by fs-laser treatment strongly increase the diamond surface electrical conductivity and a very-low activation energy is observed at room temperature. In this work, the investigation of electronic transport mechanisms of a fs-laser nanotextured diamond surface is reported. The charge transport was studied down to cryogenic temperatures, in the 30–300 K range. The samples show an activation energy of a few tens of meV in the highest temperature interval and for T < 50 K, the activation energy diminishes to a few meV. Moreover, thanks to fast cycles of measurement, we noticed that the black-diamond samples also seem to show a behavior close to ferromagnetic materials, suggesting electron spin influence over the transport properties. The mentioned properties open a new perspective in designing novel diamond-based biosensors and a deep knowledge of the charge-carrier transport in black diamond becomes fundamental.
Aging and corrosion of reinforced concrete structures (RCS) is becoming a global problem, thus proper procedures for simulating the structural performance of corroded RCS should be assessed. Among the main corrosion effects, concrete cover cracking and reinforcement cross-section reduction may influence the materials’ constitutive laws, moreover the confinement contribution and the lateral instability of the longitudinal rebars can be modified. In the present paper, the predictive models available in the scientific literature to assess the materials’ mechanical properties of corroded RCS are recalled and employed into a novel model to derive the theoretical moment–curvature relationships for the cross-section of square and rectangular corroded reinforced concrete elements. The model accounts for cover spalling, buckling of longitudinal reinforcing bars, reduction in confinement pressures, reduction in concrete constitutive law due to the concrete cracking induced by rust formation and decay of mechanical properties for corroded reinforcements. The obtained results are compared with the classical simplified models for corroded RCS, highlighting that buckling and confinement variations cannot be disregarded into a reliable modelling strategy, especially when local ductility plays a key role in the performed investigations.
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206 members
Diana Olivieri
  • Facoltà di Scienze della Formazione
Alfonso Giordano
  • Political Science
Fabrizio Patanè
  • Engineering
Renato Pisanti
  • Psychology
Andrea Orsini
  • Electronic Engineering
VIa don Carlo Gnocchi 3, 00166, Rome, Latium, Italy
Head of institution
Prof. F. Fortuna