RESUMO
This contribution reports for the first time the possibility of using radiolysis to engineer stable efficient nanofluids which exhibit an enhanced thermal conductivity. The validation was confirmed on Ag-H2O and Ag-C2H6O2 nanofluids fabricated via g-radiolysis within the mild dose range of 0.95 × 103-2.45 × 103 Gray. The enhanced thermal conductivity of Ag-H2O and Ag-C2H6O2 nanofluids, was found to be g-radiations dose dependent. In the latter case of Ag-C2H6O2 nanofluid, the relative enhancement in the temperature range of 25-50 °C was found to be 8.89%, 11.54%, 18.69%, 23.57% and 18.45% for D1 = 0.95 × 103 Gray, D2 = 1.2 × 103 Gray, D3 = 1.54 × 103 Gray, D4 = 1.80 × 103 Gray and D5 = 2.45 × 103 Gray respectively. Yet not optimized, an enhancement of the effective thermal conductivity as much as 23.57% relatively to pure C2H6O2 was observed in stable Ag-C2H6O2 nanofluids. Equivalent results were obtained with Ag-H2O.
RESUMO
PURPOSE: The purpose of our study is to determine whether there is a relation between overweight, age, sex, "hospitalised/outpatient" status and a non-inflammatory hypersignal of the subcutaneous lumbosacral adipose tissue in T2 Short-Tau Inversion-Recovery (T2-STIR) MR imaging sequences. PATIENTS AND METHODS: One hundred and six lumbar MRI, including a T2-STIR and T1 Fluid Attenuated Inversion-Recovery (FLAIR) weighted sagittal sequences, were retrospectively taken from the picture archiving and communication system (PACS) of our hospital and then made anonymous and analysed. The presence or absence of a T2-STIR hypersignal within subcutaneous adipose tissue behind the paraspinal muscle aponeurosis was determined. In addition, the weight, thickness of the fat tissue, the administrative status of the patient, the age, sex, time of the examination and, when present, the height of this hypersignal were noted. A uni- and multivariate analysis by logistic regression was carried out in order to examine the relationship between the data gathered. RESULTS: In the examinations selected, 25.5% (n=27) demonstrated a T2-STIR hypersignal in the subcutaneous tissue. We identified the weight (P<0.023), thickness of the fat tissue (P<0.001), the age of the patient (P<0.017) and the "hospitalised" status (P<0.009) as significant variables associated with this T2-STIR hypersignal. The mean height of the hypersignal was 109.5mm. Five of the 27 patients had an injection of gadolinium chelate and no enhancement was found at this level. CONCLUSION: We found a significant link between overweight, age and "hospitalised" status and the non-inflammatory infiltration of lumbar adipose tissue. This phenomenon seems to correspond with an interstitial oedema, related to subcutaneous stasis. This anomaly should not be confused with a local inflammation.
