Flow patterns and heat transfer in a square cross-section micro condenser working at low mass fluxes

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.Flow patterns and heat transfer in an air-cooled square cross-section micro condenser were investigated. The test section consisted of a borosilicate square micro channel, of inner and outer hydraulic diameters of 0.49 mm and 0.6 mm respectively, and a length of 100 mm. The transparent material of the micro channel allowed the visualization of the different condensation flow patterns. The imposed mass velocities were ranging between 1 and 10 kg m-2 s-1. In this range of mass fluxes, three main flow regimes were identified: Annular regime, intermittent regime, and spherical bubbles regime. Then, the isolated bubbles zone (the end of the intermittent zone + the spherical bubbles zone) was particularly studied. A specific experimental procedure was developed, basing on bubble tracking, in order to determine accurately the hydraulic and thermal parameters profiles in this zone according to the axial position in the micro channel, such as the vapour quality profile x(z). Thanks to energy balance, the liquid temperature profile Tl(z) in the isolated bubbles zone was determined for different initial values. A thermal non-equilibrium between the liquid and vapour phases was identified. Therefore, the latent heat flux was then quantified and compared to the total heat flux in this zone.FNRAE (MATRAS) and the Microgravity Application Program of the European Space Agenc

Risultati chirurgici a lungo termine della decompressione microvascolare nell’emispasmo facciale: efficacia, morbilità e qualità di vita

L’emispasmo facciale è una condizione clinica che può seriamente compromettere la qualità di vita del paziente. In questi casi la decompressione microvascolare rappresenta il trattamento neurochirurgico di scelta. L’obiettivo del presente lavoro è stato quello di descrivere sia l’efficacia che la morbilità della decompressione microvascolare nel trattamento dell’emispasmo facciale, di valutare l’outcome della procedura in termini di qualità di vita e di individuare eventuale fattori prognostici predittivi dell’eventuale fallimento della procedura. È stata revisionata la nostra casistica di 446 casi di emispasmo facciale trattati complessivamente nell’arco di 22 anni con 511 procedure di decompressione microvascolare con approccio retrosigmoideo. Abbiamo quindi analizzato i reperti epidemiologici, clinici e radiologici, le modalità di trattamento e gli outcome mediante la somministrazione pre e post operatoria del questionario HSF-8. Il rateo di successo è stato dell’82% dopo la prima procedura chirurgica e del 91,6 dopo la seconda procedura. Abbiamo registrato una bassa morbilità perioperatoria. La paralisi del facciale è stato per lo più un fenomeno transitorio (5,5% dei casi, permanente nello 0,2%). Nel 4,8% dei casi si è avuto invece un deficit cocleovestibolare. La chirurgia di revisione è stata invece gravata da un aumentato rateo di lesioni nervose (10.6 -20.7%). La qualità di vita a seguito della chirurgia valutata mediante HSF-8 è risultata migliore con uno score ridotto in media da 18 a 2 su 32. I fattori predittivi di fallimento chirurgico individuate sono stati I conflitti singoli (p = 0,041), conflitti atipici non coinvolgenti la PICA (p = 0,036), come quelli venosi (p = 0,045) e zone di compressione alternative all’emergenza radicolare (p = 0,027). In conclusione, la decompressione microvascolare con accesso retrosigmoideo si è rivelata essere una tecnica sicura ed efficace nel trattamento dell’emispasmo facciale. La revisione chirurgica è un opzione percorribile, ma espone a un maggior rischio di complicanze. La qualità di vita è risultata accresciuta a nel lungo termine, dimostrando un elevato grado di soddisfazione e beneficio oggettivo e soggettivo

Pumping and heat transfer enhancement by wall's morphing

In a previous study, heat transfer enhancement using a deformable wall in a heat exchanger was demonstrated numerically using CFD calculations in liquid single-phase situation. This configuration allows the pumping function to be integrated within the heat exchanger itself. Based on these results, a prototype has been developed (but with different dimensions than in the numerical study) in which one of the walls constituting the channel is subjected to dynamic deformations in the form of a traveling wave. Electric heaters on the other wall heat the channel. Actuation is achieved by means of piezoelectric actuators. Experimentally, the pumping function is observed, for all frequencies of deformations and for two different fluids (water and HFE 7000). The heat transfer intensification is also shown, and this in two experimental configurations: - a pressure difference (which may be zero) between the inlet and outlet of the channel is imposed: in this configuration, the traveling wave imposes the flow-rate. The heat transfer enhancement is then due both to the increase of the flow-rate and the disruption of the thermal boundary layers generated by the wave; - a flow-rate is imposed with a mechanical pump: in this case actuation has no effect on the pumping, and the measured heat transfer enhancement is then due only to the effects of the imposed dynamic deformations. First experiments with the presence of boiling were also performed. It was found that boiling can occur even if the fluid does not reach the saturation temperature within the channel. A 100% increase in the mean heat transfer coefficient was found when actuating the channel wall.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

Evaluation of the modified Pittsburgh classification for predicting the disease-free survival outcome of squamous cell carcinoma of the external auditory canal

Background: Squamous cell carcinoma (SCC) of the external auditory canal (EAC) is a rare disease, which is commonly classified with the modified Pittsburgh classification. Our aim was to evaluate the predictive performance of this classification in relation to disease-free survival (DFS). Methods: We examined retrospective data from a nationwide Dutch cohort study including patients with primary EAC SCC. These data were combined with individual patient data from the literature. Using the combined data, the predictive performances were calculated using the c-index. Results: A total of 381 patients were included, 294 for clinical and 281 for the pathological classification analyses. The c-indices of the clinical and the pathological modified Pittsburgh classification predicting DFS were 0.725 (0.668-0.782) and 0.729 (0.672-0.786), respectively. Conclusion: The predictive performance of the modified Pittsburgh classification system as such appears to be acceptable to predict the DFS of EAC SCC. Other factors need to be added to a future model to improve the predicted performance

The expression of p53-induced protein with death domain (Pidd) and apoptosis in oral squamous cell carcinoma

The Pidd (p53-induced protein with death domain) gene was shown to be induced by the tumour suppressor p53 and to mediate p53-dependent apoptosis in mouse and human cells, through interactions with components of both the mitochondrial and the death receptor signalling pathways. To study the role of Pidd in clinical tumours, we measured its expression by quantitative reverse transcription-PCR in microdissected oral squamous cell carcinomas (OSCC) with and without p53 mutation. Tumour cell apoptosis was assessed by in situ terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling. Tumour proliferation was assessed by immunohistochemical staining for the Ki-67 antigen. We found a wide range of Pidd expression among OSCC. Statistical analysis revealed an association between Pidd expression and apoptotic index (Mann–Whitney test, P<0.001), consistent with a role of Pidd in apoptosis in this tumour type. Furthermore, we showed a positive correlation between apoptotic index and proliferative index that has not been previously described for OSCC. There was no correlation between Pidd expression and the p53 mutation status of these tumours, suggesting that Pidd expression may be regulated by p53-independent mechanisms. Further characterisation of these molecular defects in the control of proliferation and apoptosis should help in developing treatments that target OSCC according to their biological properties

Facial nerve schwannoma in revision stapedotomy surgery

We describe a male patient who presented a progressive conductive unilateral hearing loss 20 years after otosclerosis surgery. Computed tomography (CT) scan and magnetic resonance imaging (MRI) findings suggested a facial schwannoma in its tympanic segment. At the time of revision surgery, a facial schwannoma was found to originate at the tympanic segment, pushing the prosthesis out of the oval window fenestration. The Teflon-piston was repositioned with difficulties in the central platinotomy, and the facial schwannoma was left intact

About phenomenology and modeling of dropwise condensation

International audienc