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OBJECTIVE: Transit-time flow measurement (TTFM) represents a valid tool in the assessment of the quality of the anastomosis during coronary artery bypass graft (CABG). Nevertheless, a high variability limits its standardized use, lacking univocally accepted cutoff flow values. Our study analyzes TTFM data collected from a study population that underwent off-pump CABG (OP-CABG), with the aim to differentiate into subgroups according to the presence of diabetes mellitus. PATIENTS AND METHODS: Patients referred to the Cardiovascular Unit of S. Michele Hospital (Caserta, Italy) for coronary artery disease (CAD) and underwent OP-CABG between January 2015 and December 2019 were enrolled, and intraoperative TTFMs data were recruited and evaluated. Mean graft flow (MGF) and pulsatility index (PI) values were collected and analyzed. RESULTS: The study population was composed of 342 patients who underwent OP-CABG with TTFM data regarding 824 grafts. Diabetic patients shared a higher cardiovascular risk profile. The TTFM assessment showed better results for the use of the arterial grafts in diabetic patients, especially for those insulin-dependent; conversely, venous grafts showed worse data with lower MGF and higher PI values. In particular, the anastomoses of the saphenous vein graft with marginal obtuse (MO) coronary artery showed worse MGF results in the insulin-dependent rather than normoglycemic subgroup (28.66 vs. 38.44, p=0.003). CONCLUSIONS: Diabetic patients, especially in the insulin-dependent subgroups, have demonstrated lower MGF and higher PI values collected from venous anastomoses with, conversely, inverse results from the arterial one. These results might be correlated to an altered biological adaptability caused by the effects of the diabetic endocrine disorder. [ABSTRACT FROM AUTHOR]

Due to construction tolerances, the performances of actual electromagnetic devices differ from those of the nominal design. A strategy for the search of design solutions robust against construction tolerances is presented. The approach is based on the statistical analysis of the tolerances impact on the design objective function to be evaluated. The application of the proposed strategies to the optimal design of magnetic resonance imaging magnets by a genetic algorithm shows the possibility to direct the search toward robust solutions. Index Terms--Design, genetic algorithms (GA), magnetic resonance imaging (MRI), optimization methods, robustness.

The Trommsdorff effect is a non-linear autoacceleration phenomenon in bulk free radical polymerizations. It is undesired in processes of industrial scale, as it causes hot spots and erratic behavior. In this paper a rheokinetic investigation of the Trommsdorff effect is performed with a helical barrel rheometer. This rheometer can be considered a small-scale model of large reactors, particularly extruders. The rheokinetic measurements show that the Trommsdorff effect can be reduced when the polymerization is performed at a high rotational velocity of the screw. This confirms a previous study performed with a cone and plate rheometer and is encouraging with a view to designing better-controlled bulk free radical polymerization processes of industrial scale., INTRODUCTION According to the general theory (1,2), the rate of a bulk free radical polymerization can be expressed as R = -[d[M]/dt] = [([f[k.sub.i]]/[k.sub.t])[.sup.1/2]] [k.sub.p][I.sup.1/2][M] (1) The negative sign is [...]

The dramatic increase of viscosity is a fundamental problem when designing a polymerization process. Since a thorough understanding of rheokinetics--the study of the coupled rheological changes and chemical kinetics in the reaction mixture--especially at high degrees of conversion, is still missing, industrial polymerization processes are often designed on basis of trial and error procedures and operate in far-from-optimal conditions. Even at laboratory scale the measurement of the viscosity of systems rapidly changing with time is troublesome and predicting quantitatively the increase of viscosity is not an easy task. The non-Newtonian character of polymeric systems makes rheokinetics an even more challenging field, and more interesting as well. In this review article the difficulties encountered by the research community, the results obtained so far and the problems still to be faced are discussed., INTRODUCTION When studying the kinetics of ordinary chemical reactions in the liquid phase the viscosity is not an important parameter. Both the reactants and the products are chemical compounds of [...]

The availability of new high-temperature superconducting (HTS) tapes makes possible to realize high-field HTS magnets made of such tapes, wound in 'pancake coils' shape. The critical current characteristic of firs tapes is anisotropic, and specific criteria must be adopted in the optimal design of such HTS magnets, that imply a time-consuming analysis of the magnetic field map at each step of the optimization process. In this paper, a new optimization scheme, able to deal with the firs high-field magnet design, is presented. Index Terms--High-field magnets, high-temperature superconductors, shape optimization.