Analysis of the convective heat transfer through straight fin by using the Riemann-Liouville type fractional derivative: Probed by machine learning

This work aims to analyze the transfer of heat through new fractional-order convective straight fins by using the Riemann-Liouville type fractional derivatives. The convection through the fins is considered in such a way that the thermal conductivity depends on the temperature. The transformed fractional-order problems are constituted through an optimization problem in such a way that the L 2 norm remains minimal. The objective functions are further analyzed with the hybrid Cuckoo search (HCS) algorithm that use the artificial neural network (ANN) mechanism. The impacts of the fractional parameter β, the thermo-geometric parameter of fin ψ, and dimensionless thermal conductivity α are explained through figures and tables. The fin efficiency during the whole process is explained with larger values of ψ. It is found that the larger values of ψ decline the fin efficacy. The fractional parameter declines the thermal profile as we approach the integer order. The convergence of HCS algorithm is performed in each case study. The residual error touches E - 14 for the integer order of α. The present results are validated through Table 6 by comparing with HPM, VIM and LHPM, while the error for HCS-ANN touches E - 13 . This proves that the proposed HCS is efficient.

Green and effective fabrication of porous surfaces with adjustable cell structure by foaming at incomplete healed polymer-polymer interface

Porous surfaces of materials have shown huge potentialities for endowing materials with multifarious functions. Despite introducing gas-confined-barriers in supercritical CO₂ foaming technology is effective to weaken the gas escape effect and facilitate the preparation of porous surfaces, the differences in intrinsic properties between barriers and polymers result in bottlenecks like cell structure adjustment limitation and incompletely eliminated solid skin layers. This study undertakes a preparation approach for porous surfaces by foaming at incompletely healed polystyrene/polystyrene interfaces. In contrast with employing gas-confined-barriers reported before, the porous surfaces foamed at incompletely healed polymer/polymer interfaces show a monolayer, full-open cell morphology, and wide adjustable range in cell structures including cell size (120 nm∼15.68 μm), cell density (3.40 × 10⁵ cells/cm²∼3.47 × 10⁹ cells/cm²), and surface roughness (0.50 μm∼7.22 μm). Furthermore, the wettability of obtained porous surfaces depending on the cell structures is systematically discussed. Finally, a super-hydrophobic surface with hierarchical micro-nanoscale roughness, low water adhesion, and high water-impact resistance is built by depositing nanoparticles on a porous surface. Consequently, this study offers a clean and simple method to prepare porous surfaces with adjustable cell structures, which is expected to open a door to developing a new fabrication technique for micro/nano-porous surfaces.

[Effect of porous zirconia ceramics on proliferation and differentiation of osteoblasts]

OBJECTIVE

To investigate the effect of porous surface morphology of zirconia on the proliferation and differentiation of osteoblasts.

METHODS

According to different manufacturing and pore-forming methods, the zirconia specimens were divided into 4 groups, including milled sintering group (M-Ctrl), milled porous group (M-Porous), 3D printed sintering group (3D-Ctrl) and 3D printed porous group (3D-Porous). The surface micromorphology, surface roughness, contact angle and surface elements of specimens in each group were detected by scanning electron microscope (SEM), 3D laser microscope, contact angle measuring device and energy-dispersion X-ray analysis, respectively. MC3T3-E1 cells were cultured on 4 groups of zirconia discs. The cell morphology of MC3T3-E1 cells on zirconia discs was eva-luated on 1 and 7 days by SEM. The cell proliferation was detected on 1, 3 and 5 days by cell counting kit-8 (CCK-8). After osteogenic induction for 14 days, the relative mRNA expression of alkaline phosphatase (ALP), type Ⅰ collagen (Colla1), Runt-related transcription factor-2 (Runx2) and osteocalcin (OCN) in MC3T3-E1 cells were detected by real-time quantitative polymerase chain reaction.

RESULTS

The pore size [(419.72±6.99) μm] and pore depth [(560.38±8.55) μm] of 3D-Porous group were significantly larger than the pore size [(300.55±155.65) μm] and pore depth [(69.97±31.38) μm] of M-Porous group (P < 0.05). The surface of 3D-Porous group appeared with more regular round pores than that of M-Porous group. The contact angles of all the groups were less than 90°. The contact angles of 3D-Ctrl (73.83°±5.34°) and M-Porous group (72.7°±2.72°) were the largest, with no significant difference between them (P>0.05). Cells adhered inside the pores in M-Porous and 3D-Porous groups, and the proliferation activities of them were significantly higher than those of M-Ctrl and 3D-Ctrl groups after 3 and 5 days' culture (P < 0.05). After 14 days' incubation, ALP, Colla1, Runx2 and OCN mRNA expression in 3D-Porous groups were significantly lower than those of M-Ctrl and 3D-Ctrl groups (P < 0.05). Colla1, Runx2 and OCN mRNA expressions in M-Porous group were higher than those of 3D-Porous group (P < 0.05).

CONCLUSION

The porous surface morphology of zirconia can promote the proliferation and adhesion but inhibit the differentiation of MC3T3-E1 cells.

[Effect of porous zirconia ceramics on proliferation and differentiation of osteoblasts]

OBJECTIVE

To investigate the effect of porous surface morphology of zirconia on the proliferation and differentiation of osteoblasts.

METHODS

According to different manufacturing and pore-forming methods, the zirconia specimens were divided into 4 groups, including milled sintering group (M-Ctrl), milled porous group (M-Porous), 3D printed sintering group (3D-Ctrl) and 3D printed porous group (3D-Porous). The surface micromorphology, surface roughness, contact angle and surface elements of specimens in each group were detected by scanning electron microscope (SEM), 3D laser microscope, contact angle measuring device and energy-dispersion X-ray analysis, respectively. MC3T3-E1 cells were cultured on 4 groups of zirconia discs. The cell morphology of MC3T3-E1 cells on zirconia discs was eva-luated on 1 and 7 days by SEM. The cell proliferation was detected on 1, 3 and 5 days by cell counting kit-8 (CCK-8). After osteogenic induction for 14 days, the relative mRNA expression of alkaline phosphatase (ALP), type Ⅰ collagen (Colla1), Runt-related transcription factor-2 (Runx2) and osteocalcin (OCN) in MC3T3-E1 cells were detected by real-time quantitative polymerase chain reaction.

RESULTS

The pore size [(419.72±6.99) μm] and pore depth [(560.38±8.55) μm] of 3D-Porous group were significantly larger than the pore size [(300.55±155.65) μm] and pore depth [(69.97±31.38) μm] of M-Porous group (P < 0.05). The surface of 3D-Porous group appeared with more regular round pores than that of M-Porous group. The contact angles of all the groups were less than 90°. The contact angles of 3D-Ctrl (73.83°±5.34°) and M-Porous group (72.7°±2.72°) were the largest, with no significant difference between them (P>0.05). Cells adhered inside the pores in M-Porous and 3D-Porous groups, and the proliferation activities of them were significantly higher than those of M-Ctrl and 3D-Ctrl groups after 3 and 5 days' culture (P < 0.05). After 14 days' incubation, ALP, Colla1, Runx2 and OCN mRNA expression in 3D-Porous groups were significantly lower than those of M-Ctrl and 3D-Ctrl groups (P < 0.05). Colla1, Runx2 and OCN mRNA expressions in M-Porous group were higher than those of 3D-Porous group (P < 0.05).

CONCLUSION

The porous surface morphology of zirconia can promote the proliferation and adhesion but inhibit the differentiation of MC3T3-E1 cells.

In-Vivo response to a novel pillared surface morphology for osseointegration in an ovine model

Primary stability and secondary fixation of orthopedic implants to bony tissues are important for healing and long-term functionality. Load sharing and stress transfer are key requirements of an effective implant/tissue interface. This paper presents a novel, macro-scale osseointegration surface morphology which addresses the implant/tissue interface from both the biologic as well as biomechanical perspective. The surface morphology is a controlled, engineered, open topography manifested as discrete pillars projecting from the implant enabling continuous bone ingrowth. The pillared surface is distinct from other porous surfaces and can be differentiated by the localization of the implant material into discrete pillars enabling a continuous mass of bone to freely and easily interdigitate into the pillared structure. Traditional porous structures distribute the implant material throughout the surface forcing the bone to grow in a discontinuous manner. Creating an open and continuous space or "open porosity" in and around the pillar structure allows the bone to easily interdigitate with the implant surface without encumberment from a continuous porous structure. An in-vivo study, using an established ovine model, was undertaken examining the effects of pillar morphology on bone ingrowth and mechanical performance. Cortical and cancellous sites were evaluated utilizing histology, histomophometry, and mechanical pushout, at 4 and 12 weeks. Robust bone ingrowth occurred for all morphologies as was noted in review of the study results. An increase in volume and maturity of bone was noted between the intermediated and final time points. Histomophometry demonstrated over 40% and 80% new bone occupied the available "ingrowth" area at 12 weeks for cancellous and cortical sites (respectively). Histologic review showed little fibrous tissue ingrowth at the interface with no adverse cellular reactions. Testing of cortical samples demonstrated a significant increase in pushout load between the 4 and 12 week timepoints and a 4-8 fold increase in pushout load as compared to the grit blast control. These results demonstrated the effectiveness of the novel interface for orthopedic applications in an in-vivo ovine model.

Simultaneous engineering of nanofillers and patterned surface macropores of graphene/hydroxyapatite/polyetheretherketone ternary composites for potential bone implants

Incorporating bioactive nanofillers and creating porous surfaces are two common strategies used to improve the tissue integration of polyetheretherketone (PEEK) material. However, few studies have reported the combined use of both strategies to modify PEEK. Herein, for the first time, dual nanoparticles of graphene oxide (GO) and hydroxyapatite (HAp) were incorporated into PEEK matrix to obtain ternary composites that were laser machined to create macropores with diameters ranging from 200 μm to 600 μm on the surfaces. The surface morphology and chemistry, mechanical properties, and cellular responses of the composites were investigated. The results show that micropatterned pores with a depth of 50 μm were created on the surfaces of the composites, which do not significantly affect the mechanical properties of the resultant composites. More importantly, the incorporation of GO and HAp significantly improves the cell adhesion and proliferation on the surface of PEEK. Compared to the smooth surface composite, the composites with macroporous surface exhibit markedly enhanced cell viability. The combined use of nanofillers and surface macropores may be a promising way of improving tissue integration of PEEK for bone implants.

Production and characterization of zirconia structures with a porous surface

The aim of this study was to produce zirconia structures with a porous surface by the dip coating technique and assess the mechanical properties of the structures as well as the integrity of the porous layers. Surface porous layers with homogenous and graded porosity were produced over zirconia substrate discs using zirconia powders with different average sizes (d₅₀ = 40 μm; d₅₀ = 70 μm and d₅₀ = 100 μm) and without pore forming fugitive phases. Specimens were inspected using Scanning Electron Microscopy. Bending strength of specimens was obtained from biaxial flexural tests (B3B). Porous layers were successfully produced on zirconia discs substrates and the bending strength of these specimens were ~35% lower than uncoated specimens. Delamination occurred especially in layers with higher thickness and made of bigger particles. Practical application examples were provided in this paper showing the versatility of these porous surfaces in the production of multifunctional surfaces for stronger interfaces.

The survival and inactivation of enteric viruses on soft surfaces: A systematic review of the literature

BACKGROUND

Worldwide, enteric viruses are the main cause of acute gastroenteritis. In humans, these viruses spread via person-to-person contact, food, water, and/or the environment. Their survival and inactivation on hard surfaces have been extensively studied; however, nonlaunderable soft surfaces, such as upholstery and carpet, have received little attention. The aim of this systematic review was to determine factors that influence the survival and inactivation of enteric viruses on nonlaunderable soft surfaces.

METHODS

EBSCO and Web of Science were searched for experimental studies published between 1965 and 2015 using Preferred Reporting Items for Systematic Reviews and Meta-Analyses methods. Titles and abstracts were screened using 3 eligibility criteria. The quality of all study methods was also assessed.

RESULTS

Our search yielded 12 articles. Viruses survived between 0 hours and 140 days depending on surface and environment conditions. Virus survival was influenced by temperature, relative humidity, organic content, and deposition method. A variety of chemistries were tested across studies and were shown to have a varied effect on enteric viruses. Chlorine, glutaraldehyde, vaporous ozone, and hydrogen peroxide were the most efficacious against enteric viruses (> 3-log reduction).

CONCLUSIONS

Environmental factors, such as temperature and relative humidity, can influence survival of enteric viruses on nonlaunderable soft surfaces. The efficacy of liquid and vaporous chemistries are associated with surface and virus type.