PurposeThe purpose of this research, is to develop a nano composite deposition system (NCDS) to fabricate three dimensional functional nano composite parts.Design/methodology/approachThe NCDS is a hybrid system in which material removal process by mechanical micro machining and/or the deposition process is combined.FindingsHybrid RP technology showed higher precision than those made by casting or deposition process. Tensile strength of the hydroxyapatite‐acrylic composite was about four times higher than that of resin‐only specimen while MWCNT composite did not show much improvement.Originality/valueThe paper illustrates new approaches for rapid prototyping techniques with various materials and high precision.

Purpose -Rapid prototyping (RP) technology has been widely applied in biomedical research. The purpose of this paper is to describe how a scaffold composite drug delivery system (DDS) was fabricated using a nano composite deposition system (NCDS). Design/methodology/approach -A biocompatible and biodegradable thermoplastic polymer (poly(DL-lactide-co-glycolide acid)) was used as the matrix, and a mixture of anti-cancer drug (5-fluorouracil) and bio-ceramic (hydroxyapatite -HA) was added to the polymer to form a bio-composite material for the DDS. An in vitro drug release test showed that the release rate of the drug composite could be controlled by the amount of HA for 50 days. Findings -Faster release was observed for the DDS with higher weight percent of HA. The relationship between release rate and the amount of HA showed a bi-linear manner, and bi-linear drug release models were developed based on the experimental results. Originality/value -Cylindrical scaffolds were fabricated with polymer/drug/additive using an NCDS. A series of in vitro drug release tests was performed to evaluate the effectiveness of the additive, HA. Drug release models were developed based on the experimental results.

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Three-dimensional analysis methods to calculate residual stress for functionally graded material (FGM) sample using sialon polytypoids to join silicon nitride and Alumina are introduced in this paper. The various multilayered FGM samples with 3, 9, and 20 layers were sintered to fabricate a crack-free joining of heterogeneous ceramics. To calculate three-dimensional thermal stresses of those fabricated FGM samples, a finite element analysis tool, ALGOR, was used. The Von Mises failure criterion and the maximum stress criterion were applied to predict failures in the FGM samples. For each case, calculated strength of each FGM layer by rule of mixture was compared with predicted thermal residual stresses. The Von Mises failure criterion predicted the locations of cracks more precisely than the maximum stress criterion. Such analyses are especially useful for graded FGM samples where the residual stresses are very difficult to measure experimentally.

Objective The study tried to test three existing explanations on residential segregation through spatiotemporal modeling: (1) spatial assimilation, (2) racial prejudice and discrimination, and (3) residential preferences. Since residential segregation is fundamentally a spatial and longitudinal phenomenon, the analysis is expected to provide a fresh perspective on residential segregation. Method The study used a spatiotemporal modeling through integrated nested Laplace approximation, which is a Bayesian approach to very complex regression modeling, and the data came from the American Community Survey data from 2005 to 2019 at two different spatial levels—Public Use Microdata Area and census tracts. Results The findings of this study showed that: (1) socioeconomic variables, including income, unemployment, and poverty, have meaningful impacts; (2) housing‐related variables do exert a significant impact on black household concentration; (3) the ratio of Asian and Hispanic populations turns out to be important predictors in a negative direction; and (4) even with the predictors, the non‐trivial temporal and spatiotemporal effects are discovered. Conclusion The study reveals that a reductionist approach to residential segregation is unlikely to offer meaningful insights into the problem and that proper understanding is possible only when careful consideration of the spatiotemporal context is taken, including the spatial level.