Enhanced Bone Regeneration in Rabbit Tibial Defects İmplanted with Newly Fabricated Bioceramic Bone Grafts

Hydroxyapatite (HA)‐based biografts, HBGs, were synthesized by mixing commercial HA with some additives via solgel method. The obtained HBGs were characterized by mechanical tests, X‐ray diffractometry, XRD, SEM, and FTIR. The fabricated and commercial grafts were filled into drilled zones in New Zeland rabbit tibias. The maximum stress was increased up to 332 MPa and the absorbed energy to 26.79 Joule for the yttria‐added sample H50Y10. The histopathology study suggested that better bone generation was obtained in HA‐based biografts than in control group, and it was shown that the currently fabricated biografts could be used for biomedical applications.     

CFD investigation of the flow and heat transfer characteristics in a tangential inlet cyclone

This work presents a computational fluid dynamics (CFD) calculation to investigate the flow field and the heat transfer characteristics in a tangential inlet cyclone which is mainly used for the separation of the dens phase of a two phase flow. Governing equations for the steady turbulent 3D flow were solved numerically under certain boundary conditions covering an inlet velocity range of 3 to 30 m/s. Finite volume based Fluent software was used and the RNG k −  turbulence model was adopted for the modeling highly swirling turbulent flow. Good agreement was found between computed pressure drop and experimental data available in the literature. The structure of the vortices and variation of local heat transfer were studied under the effects of inlet velocity.     

Synthesis of block copolymers by combination of ATRP and photoiniferter processes

BACKGROUND: Block copolymers of monomers polymerizing by different mechanisms can be prepared by the transformation approach. A wide range of combinations of different polymerization modes has been reported in the literature. In this work, the transformation approach was further extended to the preparation of block copolymers by combining atom transfer radical polymerization (ATRP) and photoiniferter processes. RESULTS: Photoactive morpholine‐4‐dithiocarbamate‐terminated polystyrene (MDC‐PS‐MDC) was prepared by the reaction of dibrominated polystyrene, obtained by ATRP, with morpholine‐4‐dithiocarbamate sodium salt in dimethylformamide. The structure of MDC‐PS‐MDC was confirmed by ¹H NMR and UV‐visible spectral analysis. The ability of MDC‐PS‐MDC to act as a photoiniferter for the block copolymerization of methyl acrylate was examined. The polymerization shows a ‘living’ character at up to 25% conversion and produces well‐defined polymers with molecular weights close to those predicted from theory and relatively narrow polydispersities (M_w/M_n ≈ 1.40). CONCLUSION: It is demonstrated that the end groups of polymers obtained by ATRP can be converted into morpholino‐4‐dithiocarbamate groups which act as photoiniferters. In this way, the desired mechanistic transformation between two controlled free radical polymerization methods can be achieved. Copyright © 2008 Society of Chemical Industry     

Phenacylpyridinium Oxalate as a Novel Water-Soluble Photoinitiator for Free Radical Polymerization

Summary Phenacylpyridinium oxalate (PPOx) was synthesized by counter anion exchange reaction of phenacylpyridinium bromide (PPBr) with potassium oxalate. Radicals formed from the photolysis of PPOx in aqueous solutions were capable of initiating polymerization of hydrophilic monomers such as acrylamide (AAm), 2-hydroxyethyl methacrylate (HEMA) and N-vinyl pyrrolidone (NVP). Direct decomposition of excited phenacylpyridinium ion as well as electron transfer and cleavage reactions involving both pyridinium and oxalate ions were proposed for the initiation step.     

Feedback-based event-driven parts moving

A collection of unactuated disk-shaped "parts" must be brought by an actuated manipulator robot into a specified configuration from arbitrary initial conditions. The task is cast as a noncooperative game played among the parts-which in turn yields a feedback-based event-driven approach to plan generation and execution. The correctness of this approach, an open question, has been demonstrated in simpler settings and is further suggested by the extensive experiments reported here using an actual working implementation with EDAR-a mobile robot operating in a purely feedback-based event-driven manner. These results verify the reliability of this approach against uncertainties in sensory information and unanticipated changes in workspace configuration.     

Bioceramic dip-coating on Ti–6Al–4V and 316L SS implant materials

The focus of the present study is based on more economical and rapid bioceramic coating on the most common implant substrates such as Ti–6Al–4V and 316L SS used often in orthopedics. For ceramic dip coating of implant substrates, Hydroxyapatite (HA) powder, Ca₁₀(PO₄)₆(OH)₂, P₂O₅, Na₂CO₃ and KH₂PO₄ are used to provide the gel. Ceramic films on sandblasted substrates have been deposited by using a newly manufactured dip-coating apparatus. Sample characterization is evaluated by SEM and XRD analysis. A smooth and homogeneous coating films have been obtained and average of 20 MPa bonding strength has been achieved for both Ti–6Al–4V and 316L SS alloys after sintering at 750 °C under flowing argon. The level of importance of the process parameters on coating was determined by using analysis of variance (ANOVA). The current process appears to be cheap, easy, and flexible to shape variations and high production rates for orthopedic applications.     

Learning to rank by using multivariate adaptive regression splines and conic multivariate adaptive regression splines

Learning to rank is a supervised learning problem that aims to construct a ranking model for the given data. The most common application of learning to rank is to rank a set of documents against a query. In this work, we focus on point‐wise learning to rank, where the model learns the ranking values. Multivariate adaptive regression splines (MARS) and conic multivariate adaptive regression splines (CMARS) are supervised learning techniques that have been proven to provide successful results on various prediction problems. In this article, we investigate the effectiveness of MARS and CMARS for point‐wise learning to rank problem. The prediction performance is analyzed in comparison to three well‐known supervised learning methods, artificial neural network (ANN), support vector machine, and random forest for two datasets under a variety of metrics including accuracy, stability, and robustness. The experimental results show that MARS and ANN are effective methods for learning to rank problem and provide promising results.     

An exceedingly rare localization of a brown tumor in a hemodialysis patient

Brown tumor, which is seen in the context of hyperparathyroidism, is defined as a uremic bone disease characterized by increased osteoclastic activity and fibroblastic proliferation in the involved bone. In chronic renal failure, there is an excessive parathyroid hormone secretion due to hypocalcemia, hyperphosphatemia, and vitamin D deficiency. Brown tumor of the femur, facial bones, mandible, sternum, ribs, and pelvis are rare, whereas, it rarely involves sacrum. Here, we presented a brown tumor of the sacrum that developed secondary to parathyroid hyperplasia in a patient receiving hemodialysis.     

Effects of Surface Roughness on the Performance of Tangential Inlet Cyclone Separators

This study is carried out to investigate the effects of surface roughness on the flow field and cyclone performance. The flow inside the cyclone separator is modeled as a three-dimensional turbulent continuous gas flow with solid particles as a discrete phase. The continuous gas flow is predicted by solving the governing equations by using the Reynolds Stress turbulence model, and the modeling of the particle motions is based on a Lagrangian approach. The results of the numerical simulations are compared with experimental data as well as with the results of mathematical models. Analysis of computed results shows that increase of relative roughness due to corrosion, wear, or accumulation of particles on the inner walls considerably influences the tangential velocity, cyclone separation efficiency, and cyclone pressure drop especially for high inlet velocities. Decreases in cyclone collection efficiency and pressure drop with the increase in surface roughness are found to be more pronounced for high values of relative roughness.