fabrication and characterization of an innovative heat exchanger with open cell aluminum foams

Abstract: The present study deals with the design, the fabrication and the characterization of an innovative heat exchanger manufactured by using open cell aluminum foams. The cooling performances of the heat exchanger, working in low temperature difference were measured. Open cells aluminum foams, produced via polymeric foam replication method, have been assembled to manufacture the cooling elements. The wettability of the aluminum foam surface was improved through a surface treatment, in order to enhance the joining between the pipes and the metal foam. In a first phase, preliminary experimental tests on aluminum metal foam samples were used for an estimation of the overall cooling performance. The experimental test was also aimed to understand the basic mechanisms involved in the heat transfer process. In a second phase, the full heat exchanger was assembled, and an experimental setup was designed in order to determine the performance of the heat exchanger. The heat exchanger revealed its high potentiality in terms of thermal performance, showing also a remarkable behavior in terms of energy saving, assembly and endurance

Risk of pleural mm and residual asbestos burden in the lung: a retrospective case-control study

Introduction Results of Malignant Pleural Mesothelioma (MPM) occurrence (mortality and incidence) by cumulative exposure dose clearly showed a proportional relation of MPM risk with dose, confirmed among studies by fibre burden. We evaluated the association between residual fibre content and MPM risk by circumstance of asbestos exposure. Methods and materials Lung samples obtained from pleuropneumonectomies or autopsies (349 MPMs, and 41 controls) among subjects investigated for probability and circumstance of asbestos exposure were examined through Scanning Electron Microscopy; 291 cases had an occupational asbestos exposure, 38 MPMs a non-occupational exposure (familiar or environmental), whereas among 20 MPM an asbestos exposure was not identified. The MPM risk was evaluated by means of Odds Ratio (OR). Results The residual asbestos fibre burden was higher among MPMs occupationally exposed (Geometric Mean:2.10 Million fibres/gram of dried tissue; 95% CI:1.5–2.58) in comparison with non-occupational (GM:0.66 Mff/gdt; 95% CI:0.47–0.95) or with unknown exposures (GM:0.59 Mff/gdt; 95% CI:0.34– 1.03) and controls (GM:0.26 Mff/gdt; 95% CI:0.20–0.34). Among occupationally exposed, the MPM risk increased according to the asbestos fibre burden reaching an OR of 36.8 (95%CI:11.9–113.5) for concentrations higher than 1 Mff/g dt, compared to the reference level (<0.25 Mff/gdt). Higher ORs were observed at any concentration of amphibole fibres in comparison those for chrysotile fibres. Conclusions The MPM risk was strongly associated to the residual asbestos fibre lung burden. The MPM risk due to non-occupational exposure shows a magnitude comparable with that with unknown asbestos exposures. The residual lung burden of chrysotile is strongly influenced by clearance and time since exposures ceased

Residual fibre lung burden among patients with pleural mesothelioma who have been occupationally exposed to asbestos

Objectives To evaluate the lungs asbestos fibres concentration in participants with malignant pleural mesothelioma (MPM) who have been occupationally exposed. Methods The lung samples were obtained from pleuropneumonectomies or autopsies of 271 male MPMs. The lung samples were examined through scanning electron microscopy. Retrospective assessment was used to assess for asbestos exposure. This study includes 248 MPMs with an occupational exposure defined as either ‘definite’ or ‘probable’ or ‘possible’. Results The participants had finished working in asbestos exposure conditions more than 20 years ago (on average 26.1±11.0 years). The fibre burden resulted with a geometric mean equal to 2.0 (95% CI 1.6 to 2.4) million fibres per gram of dry lung tissue. The burden was higher among participants employed in asbestos textiles industry and in shipyards with insulation material, if compared with construction workers or non-asbestos textile workers or participants working in chemicals or as auto mechanics. 91.3% of MPMs had a detectable amount of amphibole fibres. A strong lung clearance capability was evident among workers exposed to chrysotile fibres. Owing to that, the 1997 Helsinki Criteria for occupational exposure were reached in <35% of cases among participant working in construction, in metallurgical industry, in chemical or textile industry and among those performing brake repair activities. Conclusions The MPM cases are now occurring in Italy in participants who ceased occupational asbestos exposure decades before the analysis. A large majority still shows a residual content of amphibole fibres, but given the lung clearance capability, attribution to occupational exposure cannot rely only on fibres detection

Grand Unification and the Principle of Minimal Flavor Violation

Minimal Flavor Violation is an attractive approach to suppress unacceptably large flavor changing neutral currents from beyond the standard model physics at the TeV scale. It can be used in theories with low energy supersymmetry, multi Higgs doublet theories and other extensions of the minimal standard model. We show how minimal flavor violation can be implemented in Grand Unified theories.Comment: 15 pages, no figure

Composite fermions in Electroweak Symmetry Breaking

If the electroweak symmetry is broken by some unspecified strong dynamics, composite fermions may exist with definite transformation properties under SU(2)_L x SU(2)_R/SU(2)_{L+R} and may play a role in giving masses by mixing to all the standard quarks and leptons. Assuming this to be the case, we analyze the role of Singlets, Doublets and Triplets in the ElectroWeak Precision Tests and in Flavour Physics. Doublets and Triplets are generically disfavoured. In the Singlet case, we specify the breaking patterns of the flavour group that allow to keep the CKM picture of flavour physics and we discuss the effects of the mixing between composite and elementary fermions. These mixings affect in particular the rather peculiar LHC phenomenology of the composite fermions.Comment: 18 pages, 2 figures (v2: minor modifications, published version

B-decay CP-asymmetries in SUSY with a U(2)^3 flavour symmetry

We study CP asymmetries in rare B decays within supersymmetry with a U(2)^3 flavour symmetry, motivated by the SUSY flavour and CP problems, the hierarchies in the Yukawa couplings and the absence so far of any direct evidence for SUSY. Even in the absence of flavour-blind phases, we find potentially sizable CP violating contributions to b -> s decay amplitudes. The effects in the mixing-induced CP asymmetries in B ->phi K(S) and B -> eta' K(S), angular CP asymmetries in B -> K* mu+ mu- and the direct CP asymmetry in B -> X(s) gamma can be in the region to be probed by LHCb and next generation B factories. At the same time, these effects in B decays are compatible with CP violating contributions to meson mixing, including a non-standard B(s) mixing phase hinted by current tensions in the CKM fit mostly between S(psi K(S)), epsilon(K) and Delta M(B(s))/Delta M(B(d)).Comment: 13 pages, 3 figure

CP violation and Leptogenesis in models with Minimal Lepton Flavour Violation

We investigate the viability of leptogenesis in models with three heavy right-handed neutrinos, where the charged-lepton and the neutrino Yukawa couplings are the only irreducible sources of lepton-flavour symmetry breaking (Minimal Lepton Flavour Violation hypothesis). We show that in this framework a specific type of resonant leptogenesis can be successfully accomplished. For natural values of the free parameters, this mechanism requires a high right-handed neutrino mass scale (M_\nu \gsim 10^{12} GeV). By means of a general effective field theory approach, we analyse the impact of the CP violating phases responsible for leptogenesis on the low-energy FCNC observables and derive bounds on the scale of flavour violating new physics interactions. As a result of the high value of the scale of total lepton-number violation, in this class of models the $\mu\to e\gamma$ decay is expected to be close to the present exclusion limit (under the additional assumption of new particles carrying lepton flavour at the TeV scale).Comment: 19 pages, 9 figures; v2: new appendix, added note on hep-ph/0609067, and other minor modification

Re-Examination of Generation of Baryon and Lepton Number Asymmetries by Heavy Particle Decay

It is shown that wave function renormalization can introduce an important contribution to the generation of baryon and lepton number asymmetries by heavy particle decay. These terms, omitted in previous analyses, are of the same order of magnitude as the standard terms. A complete cancellation of leading terms can result in some interesting cases.Comment: 12 pages, 2 Feynman graphs (not included), UPR-055

On the Standard Model prediction for BR(B{s,d} to mu+ mu-)

The decay Bs to mu+ mu- is one of the milestones of the flavor program at the LHC. We reappraise its Standard Model prediction. First, by analyzing the theoretical rate in the light of its main parametric dependence, we highlight the importance of a complete evaluation of higher-order electroweak corrections, at present known only in the large-mt limit, and leaving sizable dependence on the definition of electroweak parameters. Using insights from a complete calculation of such corrections for K to pi bar{nu} nu decays, we find a scheme in which NLO electroweak corrections are likely to be negligible. Second, we address the issue of the correspondence between the initial and the final state detected by the experiments, and those used in the theoretical prediction. Particular attention is devoted to the effect of the soft radiation, that has not been discussed for this mode in the previous literature, and that can lead to O(10%) corrections to the decay rate. The "non-radiative" branching ratio (that is equivalent to the branching ratio fully inclusive of bremsstrahlung radiation) is estimated to be (3.23 +/- 0.27) x 10^{-9} for the flavor eigenstate, with the main uncertainty resulting from the value of f_{Bs}, followed by the uncertainty due to higher order electroweak corrections. Applying the same strategy to Bd to mu+ mu-, we find for its non-radiative branching ratio (1.07 +/- 0.10) x 10^{-10}.Comment: 15 pages. v3: very minor changes to match the journal version (EPJC