Clinical and biological data have been evaluated, using both univariate and Cox's multivariate statistical analyses, in a series of 133 Chronic Lymphocytic Leukemia (CLL) patients with a mean age of 46.6 years (range 31-50). In univariate analyses, anemia (Hb less than 13 g/dl), peripheral blood (PB) lymphocytosis (greater than 40 x 10(9)/l) and bone marrow (BM) lymphocytosis (greater than 80 per cent) were shown to be of significant prognostic value. Multivariate analysis, through a forward stepwise procedure, showed that the most important and independent variable is the BM lymphocytosis. These results are different from those obtained in previous studies and particularly in a recent identical study performed by the same Cooperative Group on 1777 patients with a mean age of 64.2 years (Mandelli et al., 1987). No significance can be demonstrated in stratifying this series of younger patients according to different staging methods (Rai et al., 1975; Binet et al., 1981b; Mandelli et al., 1987). Therefore this population of CLL patients, with less than 50 years of age, has risk factors quite different from classical CLL. The results of the present study show that the diagnostic approach to B-CLL in younger adults must be more complete: using the common diagnostic criteria, established staging systems appear to be inadequate in this series of younger patients.

The design of a functionally graded porous structure (FGPS) for use in prosthetic devices is crucial for meeting both mechanical and biological requirements. One of the most commonly used cellular structures in FGPS is the triply periodic minimal surface (TPMS) structure due to its ability to be defined by implicit equations, which allows for smooth transitions between layers. This study evaluates the feasibility of using a novel β-Ti21S alloy to fabricate TPMS-based FGPS. This beta titanium alloy exhibits low elastic modulus (53 GPa) and good mechanical properties in as-built condition. Two TPMS FGPSs with relative density gradients of 0.17, 0.34, 0.50, 0.66, and 0.83 and unit cell sizes of 2.5 mm and 4 mm were designed and fabricated using laser powder bed fusion (LPBF). The as-manufactured structures were analyzed using scanning electron microscopy (SEM) and X-ray micro-computed tomography (μ-CT), and the results were compared to the design. The analysis revealed that the pore size and ligament thickness were undersized by less than 5%. Compression tests showed that the stabilized elastic modulus was 4.1 GPa for the TPMS with a 2.5 mm unit cell size and 10.7 GPa for the TPMS with a 4 mm unit cell size. A finite element simulation was performed to predict the specimen’s elastic properties, and a lumped model based on lattice homogenized properties was proposed and its limitations were explored.

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Functionally graded porous structures (FGPSs) are attracting increasing interest in the manufacture of prostheses that benefit from lower stiffness and optimized pore size for osseointegration. In this work, we explore the possibility of employing FGPSs with auxetic unit cells. Their negative Poisson’s ratio was exploited to reduce the loss of connection between prosthesis and bone usually occurring in standard implant loaded under tension and therefore undergoing lateral shrinking. In addition, to further improve osseointegration and mitigate stress shielding effects, auxetic FGPSs were fabricated in this work using a novel β-Ti21S alloy characterized by a lower Young’s modulus compared to traditional α + β Ti alloys. Specifically, two different auxetic FGPSs with aspect ratio equal to 1.5 and angle θ of 15° and 25° with a relative density (ρr) gradient of 0.34, 0.49, 0.66 and of 0.40, 0.58, 0.75 were designed and printed by laser powder bed fusion. The 2D and 3D metrological characterization of the as-manufactured structures was compared with the design. 2D metrological characterization was carried out using scanning electron microscopy analysis, while for the 3D characterization, X-ray micro-CT imaging was used. An undersizing of the pore size and strut thickness in the as-manufactured sample was observed in both auxetic FGPSs. A maximum difference in the strut thickness of −14 and −22% was obtained in the auxetic structure with θ = 15° and 25°, respectively. On the contrary, a pore undersizing of −19% and −15% was evaluated in auxetic FGPS with θ = 15° and 25°, respectively. Compression mechanical tests allowed to determine stabilized elastic modulus of around 4 GPa for both FGPSs. Homogenization method and analytical equation were used and the comparison with experimental data highlights a good agreement of around 4% and 24% for θ = 15° and 25°, respectively.