Commercial refrigeration - An overview of current status

[EN] Commercial Refrigeration comprises food freezing and conservation in retail stores and supermarkets, so, it is one of the most relevant energy consumption sectors, and its relevance is increasing. This paper reviews the most recent developments in commercial refrigeration available in literature and presents a good amount of results provided these systems, covering some advantages and disadvantages in systems and working fluids. Latest researches are focused on energy savings to reduce CO2 indirect emissions due to the burning of fossil fuels. They are focused on system modifications (as dedicated subcooling or the implementation of ejectors), trigeneration technologies (electrical, heating and cooling demand) and better evaporation conditions control. Motivated by latest GWP regulations that are intended to reduce high GWP HFC emissions; R404A and R507 are going to phase out. Besides hydrocarbons and HFO, CO2 appears as one of the most promising HFC replacements because its low contribution to global warming and high efficiencies when used in transcritical and low-stage of cascade systems.The authors thankfully acknowledge "Ministerio de Educacion, Cultura y Deporte" for supporting this work through "Becas y Contratos de Formacion de Profesorado Universitario del Programa Nacional de Formacion de Recursos Humanos de Investigacion del ejercicio 2012".Mota Babiloni, A.; Navarro Esbri, J.; Barragán Cervera, Á.; Moles, F.; Peris, B.; Verdú Martín, GJ. (2015). Commercial refrigeration - An overview of current status. International Journal of Refrigeration. 57:186-196. doi:10.1016/j.ijrefrig.2015.04.013S1861965

Muscle cramping during exercise : causes, solutions and questions remaining

Muscle cramp is a temporary but intense and painful involuntary contraction of skeletal muscle that can occur in many different situations. The causes of, and cures for, the cramps that occur during or soon after exercise remain uncertain, although there is evidence that some cases may be associated with disturbances of water and salt balance, while others appear to involve sustained abnormal spinal reflex activity secondary to fatigue of the affected muscles. Evidence in favour of a role for dyshydration comes largely from medical records obtained in large industrial settings, although it is supported by one large-scale intervention trial and by field trials involving small numbers of athletes. Cramp is notoriously unpredictable, making laboratory studies difficult, but experimental models involving electrical stimulation or intense voluntary contractions of small muscles held in a shortened position can induce cramp in many, although not all, individuals. These studies show that dehydration has no effect on the stimulation frequency required to initiate cramping and confirm a role for spinal pathways, but their relevance to the spontaneous cramps that occur during exercise is questionable. There is a long history of folk remedies for treatment or prevention of cramps; some may reduce the likelihood of some forms of cramping and reduce its intensity and duration, but none are consistently effective. It seems likely that there are different types of cramp that are initiated by different mechanisms; if this is the case, the search for a single strategy for prevention or treatment is unlikely to succeed.Publisher PDFPeer reviewe

Novel Muscle Imaging in Inflammatory Rheumatic Diseases—A Focus on Ultrasound Shear Wave Elastography and Quantitative MRI

In recent years, imaging has played an increasing role in the clinical management of patients with rheumatic diseases with respect to aiding diagnosis, guiding therapy and monitoring disease progression. These roles have been underpinned by research which has enhanced our understanding of disease pathogenesis and pathophysiology of rheumatology conditions, in addition to their key role in outcome measurement in clinical trials. However, compared to joints, imaging research of muscles is less established, despite the fact that muscle symptoms are very common and debilitating in many rheumatic diseases. Recently, it has been shown that even though patients with rheumatoid arthritis may achieve clinical remission, defined by asymptomatic joints, many remain affected by lingering constitutional systemic symptoms like fatigue, tiredness, weakness and myalgia, which may be attributed to changes in the muscles. Recent improvements in imaging technology, coupled with an increasing clinical interest, has started to ignite new interest in the area. This perspective discusses the rationale for using imaging, particularly ultrasound and MRI, for investigating muscle pathology involved in common inflammatory rheumatic diseases. The muscles associated with rheumatic diseases can be affected in many ways, including myositis—an inflammatory muscle condition, and myopathy secondary to medications, such as glucocorticoids. In addition to non-invasive visual assessment of muscles in these conditions, novel imaging techniques like shear wave elastography and quantitative MRI can provide further useful information regarding the physiological and biomechanical status of the muscle

L’elettrostimolazione neuromuscolare: basi fisiologiche e principi di utilizzo (prima parte)

nel numero precedente sono state trattate le basi fisiologiche dell’attivazione neuromuscolare e i principi della registrazione elettromiografica (EMG), che consente di analizzare l’attività delle unità motorie attive durante una contrazione. Moltissimi studi, condotti con registrazioni EMGsia intramuscolari sia di superficie, hanno permesso di definire che l’attivazione neuromuscolare si realizza attraversolacombinazionedi reclutamentodiunitàmotorieemodulazionedellaloro frequenza di scarica. Inoltre, la strategia di attivazione delle unitàmotorie varia tra ognimuscolo epersino tra ognigestomotorio.Questo rende complicato e, al contempo, affascinantelostudiodegliadattamentineuromuscolariall’allenamento,che si realizzano, infunzionedideterminatimeccanisminonancoradel tuttonoti, siasul versantemuscolare sia su quello nervoso

Elettrostimolazione neuromuscolare: tecniche, parametri e protocolli (seconda parte)

L’elettrostimolazione neuromuscolare consiste nell’attivazione di fibre nervose attraverso l’applicazione di impulsi elettrici tramite elettrodi posizionati sulla cute sovrastante il muscolo di interesse. Nel presente articolo gli Autori riportano informazioni relative a come posizionare gli elettrodi di stimolazione, quali parametri della stimolazione occorra considerare per un corretto uso della tecnica e dei vari protocolli di stimolazione, quali prove di efficacia siano state raccolte in ambito di applicazione della stimolazione finalizzata all’incremento prestativo in soggetti sani sedentari o atleti