Heat Transfer in Gaseous Microflows: Conjugate Heat Transfer, Rarefaction and Compressibility Effects

Development of Conjugate Heat Transfer models to study the behavior of heat exchange in gaseous microflows. At the scales considered, rarefaction effects play a relevant role so that the need to involve slip flow boundary conditions is fundamental. The wide development of MEMS application, the very fast development in microfabrication technologies, and the increasing industrial applications of microfluidic systems, which are all taking place and evolving in the last decades, require a better knowledge of the behavior of microfluidic systems, especially of gases, which haven\u2019t been yet understood as well as liquid ones have. Flows that are involved in this realm have characteristic dimensions of the order of tens of micrometers. The object of this work is essentially the investigation, and evaluation, of the characteristics and performances of forced convection in micro channels and of Micro Heat Exchangers. A general correlation for the local Stagnation Nusselt number is derived, which is in good agreement with all the results obtained in the study, and it has been proven that it works for the convection heat transfer cases with compressibility effects in the Micro Heat Exchange

Soil hydrology in agriculture

Understanding the hydrological behavior of soils is essential for managing and protecting agricultural (and natural) ecosystems. Soil hydrological behavior not only mainly determines crop responses to water and nutrients provided by irrigation and fertilization, but also the timing for soil tillage, environmental conditions for plant diseases, among other factors. In the sound management of irrigation water, in relation to specific environmental conditions and cropping systems, the knowledge of local water flow conditions in zones explored by the root systems is indispensable. Once the irrigation method has been established, only the knowledge of the laws governing water flow allows for the establishment of the necessary irrigation frequencies and rates to optimize the distribution of soil moisture, reducing the effects of water stress within the established limits and containing water wastage. Soil hydrology also controls deep percolation fluxes of water and nutrients, as well as water and nutrient runoff. Only by studying water dynamics in soil can the contribution of groundwater to water consumption be quantitatively determined. Moreover, the water volumes infiltrating into the soil due to rainfall are strictly linked and governed by the laws of water flow in the soil. No evaluation of water quantities being added to groundwater circulation can be made without first determining the water volumes moving in the zone between the soil surface and aquifer. The use of process-based soil-plant-atmosphere models, relating soil hydrology to crop growth, dates back several decades ago [1]. More recently, models are incorporated in decision support systems to be used for quantifying the effect of alternative farm managements [2], among many other decisions, such as landscape planning [3] and crop yield responses as affected by climatic change [4]. This, in turn, may allow for site-specific management of spatially variable soil (Agriculture 4.0). It is thus evident that soil hydrology is a key factor in food security and sustainable development goals (SDG2) [5,6]. The crucial link between soil hydrology and optimal management of water and solutes in agriculture calls for advancements in field-based monitoring and prediction tools for a better understanding of water and nutrient balance and, specifically, of all the functional processes involved (namely, evapotranspiration, groundwater recharge, nutrient and salt transport) [7,8]. Understanding these processes has obvious consequences on the water and solute management in agriculture, suggesting optimal irrigation methods, water volumes and fertilizer amounts to keep crop yields, while minimizing environmental problems (e.g., nitrate leaching towards groundwater, soil salinization). The complexity of soil water flow and solute transport processes has encouraged the widespread use of mathematical models, corresponding as closely as possible to real phenomena [9]. Efforts have been mainly devoted to develop increasingly sophisticated parameterizations of the interaction between soil, vegetation and the atmosphere in the so-called soil–plant–atmosphere continuum (SPAC) transfer schemes [10,11]. The estimation of water and solute balances at different spatial and temporal scales is a fundamental task of these models. Under most climatic conditions, the ability of the root zone to match evapotranspiration and precipitation depends on the soil’s infiltration capacity, root zone storage and water-holding capacity, as well as on the temporal dynamics of the precipitation process, relative to that of evapotranspiration. Knowledge of the physical and hydraulic properties of the shallow vadose zone is, therefore, a key element in correctly modeling the soil–groundwater–atmosphere exchange processes. Moreover, for large-scale applications, an evaluation in statistical terms of the variability of these properties is also necessary [12]. The body of knowledge on the link between hydrology and agriculture available at present, both theoretical and experimental, is extensive. Nevertheless, knowledge gaps still exist. The purpose of this special issue is to fill some of these gaps. In this sense, the papers selected for this special issue address a range of issues—all deal with the interaction of soil hydrology and agriculture in seeking effective management of water and nutrients. Most of the contributions integrate monitoring and modeling components at applicative scales, from field to district scales. Specifically, this special issue deals with the following major topics: Hydrological properties for model applications and their changes over time; Model calibration and water balance; Irrigation management and effects on soil hydrological processes and salinity. In the following paragraphs, details of each of the papers included in each of these major topics will be provided

Pain perception and migraine

Background: It is well-known that both inter-and intra-individual differences exist in the perception of pain; this is especially true in migraine, an elusive pain disorder of the head. Although electrophysiology and neuroimaging techniques have greatly contributed to a better understanding of the mechanisms involved in migraine during recent decades, the exact characteristics of pain threshold and pain intensity perception remain to be determined, and continue to be a matter of debate.Objective: The aim of this review is to provide a comprehensive overview of clinical, electrophysiological, and functional neuroimaging studies investigating changes during various phases of the so-called "migraine cycle" and in different migraine phenotypes, using pain threshold and pain intensity perception assessments.Methods: A systematic search for qualitative studies was conducted using search terms "migraine," "pain," "headache," "temporal summation," "quantitative sensory testing," and "threshold," alone and in combination (subject headings and keywords). The literature search was updated using the additional keywords "pain intensity," and "neuroimaging"to identify full-text papers written in English and published in peer-reviewed journals, using PubMed and Google Scholar databases. In addition, we manually searched the reference lists of all research articles and review articles.Conclusion: Consistent data indicate that pain threshold is lower during the ictal phase than during the interictal phase of migraine or healthy controls in response to pressure, cold and heat stimuli. There is evidence for preictal sub-allodynia, whereas interictal results are conflicting due to either reduced or no observed difference in pain threshold. On the other hand, despite methodological limitations, converging observations support the concept that migraine attacks may be characterized by an increased pain intensity perception, which normalizes between episodes. Nevertheless, future studies are required to longitudinally evaluate a large group of patients before and after pharmacological and non-pharmacological interventions to investigate phases of the migraine cycle, clinical parameters of disease severity and chronic medication usage

Effect of high level of bladder filling on spinal nociception and motoneuronal excitability

To verify whether high level of bladder distension may counteract the inhibitory effect of descending pathways on sacral spinal cord neurons and to investigate which spinal circuitries are possibly involved in such a viscero-somatic interaction. Nociceptive withdrawal reflex (NWR), cutaneous silent period (CSP), and H-reflex were recorded in both lower and upper limbs of twenty-eight healthy subjects. Subjects were examined during baseline (empty bladder, no voiding desire), high level of bladder filling (urgency desire), and control (empty bladder, no voiding desire) sessions. Results showed that the NWR and its related pain perception were reduced in the upper limbs, while only a pain perception reduction in males was observed in the lower limbs. The H-reflex was inhibited in both limbs. No effects were found on the CSP duration. The decrease in both the NWR and its related pain perception in the upper limbs confirms the presence of a bladder distension-induced descending inhibitory modulation on nociception at spinal level. The lack of a similar inhibitory effect in the lower limbs suggests that excitatory nociceptive inputs from bladder afferents counterbalance the inhibitory effect on sacral spinal cord. The lack of the descending inhibitory effect may be a mechanism aimed at forcing the micturition phase to avoid bladder damage caused by bladder sovradistension

Malattie podaliche del bovino. Diagnosi e strategie terapeutiche in alcune aziende di bovine lattifere

Negli allevamenti di bovine lattifere le lesioni digitali interessano percentuali rilevanti di animali. Le patologie del piede sono la principale causa di zoppia ed il problema assume una notevole importanza dal punto di vista economico. Vista la diffusione delle patologie podaliche e le perdite che ne derivano, è opportuno un approccio complessivo alla gestione della mandria, con strategie preventive e protocolli di trattamento per ridurre e controllare la zoppia. Pur essendo ormai note da tempo e considerate chiaramente efficaci le normali misure preventive, il problema della zoppia rimane nella pratica ancora aperto. La scopo del lavoro è stato quello di utilizzare la visita clinica come indicatore della gestione degli allevamenti, per l’eventuale identificazione di punti critici. È stata eseguita un’indagine in alcuni allevamenti di bovine lattifere della pianura padana. La visita clinica è stata effettuata sugli animali in sede di pareggio, oltre alla diagnosi clinica è stata effettuata una valutazione del grado di zoppia, utilizzando il “locomotion score”, una valutazione dello stato di nutrizione degli animali con il “body condition score” e la valutazione della gestione degli allevamenti attraverso una scheda di allevamento riguardante i vari aspetti gestionali. I risultati hanno evidenziato una chiara relazione tra l’incidenza di lesioni digitali e punti critici gestionali

Pedotechniques strategies to improve soil resilience against the impact of irrigation by municipal wastewater: using zeolitized tuffs as soil amendments

A research was started aiming at evaluating the possible use of natural zeolites as exchange conditioners to improve and make durable the soil resilience against the adverse effects of the use of anomalous wastewater, for irrigation purposes. To satisfy such aims, two zeolitized tuffs (ZTs), viz. a Neapolitan yellow tuff (NYT) and a clinoptilolite bearing tuff (ZCL), were tested as pedotechnical materials to improve soil resilience against the impact of treatment by a ‘dirty’ municipal wastewater (DMW)

A soil non-aqueous phase liquid (NAPL) flushing laboratory experiment based on measuring the dielectric properties of soil–organic mixtures via time domain reflectometry (TDR)

Abstract. The term non-aqueous phase liquid (NAPL) refers to a group of organic compounds with scarce solubility in water. They are the products of various human activities and may be accidentally introduced into the soil system. Given their toxicity level and high mobility, NAPLs constitute a serious geo-environmental problem. Contaminant distribution in the soil and groundwater contains fundamental information for the remediation of polluted soil sites. The present research explored the possible employment of time domain reflectometry (TDR) to estimate pollutant removal in a silt-loam soil that was primarily contaminated with a corn oil as a light NAPL and then flushed with different washing solutions. Known mixtures of soil and NAPL were prepared in the laboratory to achieve soil specimens with varying pollution levels. The prepared soil samples were repacked into plastic cylinders and then placed in testing cells. Washing solutions were then injected upward into the contaminated sample, and both the quantity of remediated NAPL and the bulk dielectric permittivity of the soil sample were determined. The above data were also used to calibrate and validate a dielectric model (the α mixing model) which permits the volumetric NAPL content (θNAPL; m3 m−3) within the contaminated sample to be determined and quantified during the different decontamination stages. Our results demonstrate that during a decontamination process, the TDR device is NAPL-sensitive: the dielectric permittivity of the medium increases as the NAPL volume decreases. Moreover, decontamination progression can be monitored using a simple (one-parameter) mixing model