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The Italian Natural Gas (NG) distribution network includes thousands of NG metering and pressure reduction stations, called City Gate Stations (CGS), for injecting gas into low-pressure networks. These plants are mainly based on the isenthalpic throttling of the gas flow to reduce its pressure, which leads to a significant reduction of its temperature by the Joule-Thompson effect. Gas preheating systems that avoid excessive cooling are installed upstream of pressure reduction valves and usually exploit conventional gas boilers. The energy consumption and carbon footprint could be reduced by integrating heat pumps coupled with renewable energy sources for NG preheating to support gas boilers. For this work, an ad-hoc thermodynamic model for estimating the thermal energy demand for pre-heating is developed, exploiting experimental data from a real CGS, and simplified models of heat pumps and renewable systems. This work aims to assess the actual technical and economic feasibility of energy savings through these technologies. Results show the validated model to be sufficiently accurate to estimate the need for gas preheating for these applications. For the considered case study, up to 38%, 32%, or 26% of the total thermal energy can be recovered with a PBT of less than 20 years, 15, and about 13 years, respectively.

The objective of this work was to demonstrate the phytoremediation effect of Azolla sp. in water artificially contaminated with lead and planted with rice seeds. A completely randomized 4x3 design was applied. The percentage of germination of the rice seeds, the length of the radicle and the epicotyl were determined. Chemical analyzes were performed using the inductively coupled plasma optical emission spectroscopy (ICP-OES) method. The results showed that 81.03% of the rice seeds germinated in contact with lead-contaminated water, which when combined with Azolla in the lead-contaminated medium only germinated 66.60%, while when they were both rice seeds like Azolla without the contaminant germinated 66.1%. Regarding the length of the epicotyl, it could be observed in the treatment where the rice seeds were in contact with the contaminant. Regarding the phytoremediation effect of Azolla, it was found that Azolla has the ability to capture lead, however, when rice seeds are in an aquatic environment not associated with Azolla, they can bioaccumulate this heavy metal.

Oscillating water column (OWC) systems are among the most credited solutions for an effective conversion of the notable energy potential conveyed by sea waves. Despite a renewed interest, however, they are often still at a demonstration phase and additional research is required to reach industrial maturity. Within this framework, this study provides a wave-to-wire model for OWC systems based on an impulse air turbine. The model performs a comprehensive simulation of the system to estimate the attendant electric energy production for a specific sea state, based on analytical models of the primary (fixed chamber) and secondary (air turbine) converters coupled with the tertiary converter (electric generator). A rigid piston model is proposed to solve the hydrodynamics, thermodynamics, and hydrodynamics of the chamber, in a coupled fashion with the impulse turbine aerodynamics. This is solved with a novel method by considering the cascades as sets of blades, each one consisting of a finite number of airfoils stacked in the radial direction. The model was applied for two Mediterranean sites located in Tuscany and Sardinia (Italy), which were selected to define the optimal geometry of the turbine for a specified chamber. For each system, the developed analytical wave-to-wire model was applied to calculate the performance parameters and the annual energy production in environmental conditions typical of the Mediterranean Sea. The selected impulse turbines are able to convert 13.69 and 39.36 MWh/year, with an efficiency of 4.95% and 4.76%, respectively, thus proving the interesting prospects of the technology.

We present an effective evolution equation for a coarse-grained distribution function of a long-range-interacting system preserving the symplectic structure of the noncollisional Boltzmann, or Vlasov, equation. First, we derive a general form of such an equation based on symmetry considerations only. Then we explicitly derive the equation for one-dimensional systems, finding that it has the form predicted on general grounds. Finally, we use this equation to predict the dependence of the damping times on the coarse-graining scale and numerically check it for some one-dimensional models, including the Hamiltonian mean-field model, a scalar field with quartic interaction, a 1-d self-gravitating system, and a self-gravitating ring.

This paper presents an off-design analysis of a gas turbine Organic Rankine Cycle (ORC) combined cycle. Combustion turbine performances are significantly affected by fluctuations in ambient conditions, leading to relevant variations in the exhaust gases’ mass flow rate and temperature. The effects of the variation of ambient air temperature have been considered in the simulation of the topper cycle and of the condenser in the bottomer one. Analyses have been performed for different working fluids (toluene, benzene and cyclopentane) and control systems have been introduced on critical parameters, such as oil temperature and air mass flow rate at the condenser fan. Results have highlighted similar power outputs for cycles based on benzene and toluene, while differences as high as 34% have been found for cyclopentane. The power output trend with ambient temperature has been found to be influenced by slope discontinuities in gas turbine exhaust mass flow rate and temperature and by the upper limit imposed on the air mass flow rate at the condenser as well, suggesting the importance of a correct sizing of the component in the design phase. Overall, benzene-based cycle power output has been found to vary between 4518 kW and 3346 kW in the ambient air temperature range considered.

In nonadditive systems, like small systems or like long-range interacting systems even in the thermodynamic limit, ensemble inequivalence can be related to the occurrence of negative response functions, this in turn being connected with anomalous concavity properties of the thermodynamic potentials associated with the various ensembles. We show how the type and number of negative response functions depend on which of the quantities E, V and N (energy, volume and number of particles) are constrained in the ensemble. In particular, we consider the unconstrained ensemble in which E, V and N fluctuate, which is physically meaningful only for nonadditive systems. In fact, its partition function is associated with the replica energy, a thermodynamic function that identically vanishes when additivity holds, but that contains relevant information in nonadditive systems.

What happens when one of the parameters governing the dynamics of a long-range interacting system of particles in thermal equilibrium is abruptly changed (quenched) to a different value? While a short-range system, under the same conditions, will relax in time to a new thermal equilibrium with a uniform temperature across the system, a long-range system shows a fast relaxation to a non-equilibrium quasistationary state (QSS). The lifetime of such an off-equilibrium state diverges with the system size, and the temperature is non-uniform across the system. Quite surprisingly, the density profile in the QSS obtained after the quench is anticorrelated with the temperature profile in space, thus exhibiting the phenomenon of temperature inversion : denser regions are colder than sparser ones. We illustrate with extensive molecular dynamics simulations the ubiquity of this scenario in a prototypical long-range interacting system subject to a variety of quenching protocols, and in a model that mimics an experimental setup of atoms interacting with light in an optical cavity. We further demonstrate how a procedure of iterative quenching combined with filtering out the high-energy particles in the system may be employed to cool the system. Temperature inversion is observed in nature in some astrophysical settings; our results imply that such a phenomenon should be observable, and could even be exploitable to advantage, also in controlled laboratory experiments.

Objectives: To compare the performance of a handheld fundus camera with standard 50° visual field to ultra-widefield (UWF) table-top fundus camera in diabetic retinopathy (DR) detection and grading., Methods: Patients affected by diabetes mellitus and referred to our diabetic retinopathy clinic were enroled and underwent fundus photography in mydriasis. All photos were taken using the ultra-widefield table-top fundus camera Zeiss Clarus™ 500 (four fields per eye) and the Optomed Aurora® handheld fundus camera (3 fields per eye). The following parameters were analysed: the gradability of the images, the grade of DR, and diabetic maculopathy (DM), the presence of hypertensive retinopathy (HR) and the presence of other ocular diseases., Results: We enroled 759 eyes of 384 diabetic patients and analysed 5313 fundus photos. The handheld fundus camera obtained a sensitivity of 84.2% and specificity of 95.4% for referable cases. Moreover, it obtained, compared to UWF, an almost perfect agreement with linear weighting for DR, DM and HR (k = 0.877, k = 0.854, and k = 0.961, respectively). The lowest sensitivity was achieved for proliferative DR (58.7% sensitivity, 100% specificity)., Conclusions: Optomed Aurora® handheld fundus camera imaging showed a strong agreement compared to UWF in grading DR, considering all DR and DM grades, in mydriasis. However, the use of UWF imaging increases the detection of referable eyes., (© 2023. The Author(s), under exclusive licence to The Royal College of Ophthalmologists.)

The aim of the study was to validate the performance of the Optomed Aurora ® handheld fundus camera in diabetic retinopathy (DR) screening. Patients who were affected by diabetes mellitus and referred to the local DR screening service underwent fundus photography using a standard table-top fundus camera and the Optomed Aurora ® handheld fundus camera. All photos were taken by a single, previously unexperienced operator. Among 423 enrolled eyes, we found a prevalence of 3.55% and 3.31% referable cases with the Aurora ® and with the standard table-top fundus camera, respectively. The Aurora ® obtained a sensitivity of 96.9% and a specificity of 94.8% in recognizing the presence of any degree of DR, a sensitivity of 100% and a specificity of 99.8% for any degree of diabetic maculopathy (DM) and a sensitivity of 100% and specificity of 99.8% for referable cases. The overall concordance coefficient k (95% CI) was 0.889 (0.828-0.949) and 0.831 (0.658-1.004) with linear weighting for DR and DM, respectively. The presence of hypertensive retinopathy (HR) was recognized by the Aurora ® with a sensitivity and specificity of 100%. The Optomed Aurora ® handheld fundus camera proved to be effective in recognizing referable cases in a real-life DR screening setting. It showed comparable results to a standard table-top fundus camera in DR, DM and HR detection and grading. The Aurora ® can be integrated into telemedicine solutions and artificial intelligence services which, in addition to its portability and ease of use, make it particularly suitable for DR screening.

The tendency to live alone is a relatively recent phenomenon in Ecuador, but it is expanding rapidly. This study aims to identify factors associated with financial distress/well-being according to living situation (living alone vs. living with a partner) in Ecuadorian health workers. This study examined the construct of financial distress/well-being in a sample of 800 Ecuadorian health workers using cross-sectional data. Living situation was compared using generalized linear model analyses including income, age, children living at home, self-perception of health, depression, anxiety and stress, perceived social support, positive mental health, and hedonistic and austere profiles. Regarding financial well-being, workers living alone ranked lower and workers living with a partner ranked higher. In workers living alone the main sources of financial distress/well-being were income, children living at home, perceived social support, positive mental health, and hedonistic attitude towards indebtedness. In workers living with a partner the main sources of financial distress/well-being were income, age, self-perception of health, depression, anxiety and stress, perceived social support, positive mental health, and austere attitude towards indebtedness. Based on our results, we discuss potential public policy interventions that can be used to improve workers' financial well-being.

Objective: To identify variables that explain satisfaction with food-related life in Ecuadorian elderly people., Design: Stratified random sampling with proportional affixation within each retirement home was conducted based on the rate of rurality, gender, age, and living circumstances., Setting: Retirement homes in Guayaquil, Ecuador., Participants: The sample consisted of 817 elderly people of both genders (47.5% women; mean age 73.7 years; SD 7.45 years; range 60-101 years) registered in retirement homes located in Guayaquil, Ecuador., Main Outcome Measures: Satisfaction With Life scale, satisfaction with food-related life (SWFL), and 22 food-related perceived resources., Analysis: Generalized linear models., Results: Gender, food consumption expenditure, satisfaction with economic situation, unhealthy days, family importance, food-related lifestyles, food neophobia, and the sum of 22 resources were found to be associated with SWFL. In addition, the Pearson bivariate correlation between the Satisfaction With Life scale and SWFL was .38 (P < .01)., Conclusions: Perceived resources contributed to SWFL and the greatest satisfaction with life was observed among older adults who were more satisfied with their food., (Copyright © 2019 Society for Nutrition Education and Behavior. Published by Elsevier Inc. All rights reserved.)