Morphological Change of Heat Treated Bovine Bone: A Comparative Study

In this work, untreated bovine cortical bones (BCBs) were exposed to a range of heat treatments in order to determine at which temperature the apatite develops an optimum morphology comprising porous nano hydroxyapatite (nanoHAp) crystals. Rectangular specimens (10 mm × 10 mm × 3–5 mm) of BCB were prepared, being excised in normal to longitudinal and transverse directions. Specimens were sintered at up to 900 °C under ambient pressure in order to produce apatites by two steps sintering. The samples were characterized by thermogravimetric analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM) attached to an energy-dispersive X-ray spectroscopy detector. For the first time, morphology of the HAp particles was predicted by XRD, and it was verified by SEM. The results show that an equiaxed polycrystalline HAp particle with uniform porosity was produced at 900 °C. It indicates that a porous nanoHAp achieved by sintering at 900 °C can be an ideal candidate as an in situ scaffold for load-bearing tissue applications.     

The Zadek calcaneal osteotomy in Haglund’s syndrome of the heel: Its effects on the dorsiflexion of the ankle and correlations to clinical and functional scores

The Zadek osteotomy is a therapeutic option in Haglund’ syndrome for patients with a X/Y ratio measurement of the calcaneus under 2.5. We hypothesized that Zadek osteotomy would lead to improvement in ankle dorsiflexion and functional scores.Twenty-two patients (mean age: 48.5 years) with Haglund’s syndrome underwent a Zadek osteotomy and were enrolled in a prospective study investigating the proposed hypothesis. Radiological measurements included the X/Y ratio and the pitch angle. Measurements of the dorsiflexion of the ankle, using a hand-made frame, were performed twice by 2 independent observers. Inter and intra classes correlations were calculated. Functional results were assessed using AOFAS, EFAS and EFAS sport. Correlation between ankle dorsiflexion and functional scores were determined using linear regression curves.Our hypothesis was validated with a mean improvement of dorsiflexion of 7.27° (54.98% improvement from pre-operative measurement) (p < 0.0001). Ankle dorsiflexion measurements were highly reproducible with an interclass correlation coefficient(ICC)> 0.95 (0.98–0.99). All mean values of functional scores were significantly improved(p < 0.05) [AOFAS (61.95–94), EFAS (14–21.82), EFAS sport (7.68–13.69)] and were strongly correlated to the dorsiflexion values with a coefficient of determination of 0.82 for AOFAS and EFAS and of 0.86 for EFAS sport, respectively. The mean values of X/Y ratio and pitch angle improved from pre to postoperative conditions, 2.18–2.75 and 28.95–19.77° (p < 0.05), respectively.The angle correction obtained from modifiying the shape of the calcaneus, due to the Zadek osteotomy, confirms it as a safe and reliable treatment, with improvements of both ankle dorsiflexion and functional scores.     

High‐resolution creatine mapping of mouse brain at 11.7 T using non‐steady‐state chemical exchange saturation transfer

The current study aims to optimize the acquisition scheme for the creatine chemical exchange saturation transfer weighted (CrCESTw) signal on mouse brain at 11.7 T, in which a strong magnetization transfer contrast (MTC) is present, and to further develop the polynomial and Lorentzian line‐shape fitting (PLOF) method for quantifying CrCESTw signal with a non‐steady‐state (NSS) acquisition scheme. Studies on a Cr phantom with cross‐linked bovine serum albumin (BSA) as well as on mouse brain demonstrated that the maximum CrCESTw signal was reached with a short saturation time determined by the rotating frame relaxation time of the MTC pool instead of the steady‐state saturation. The saturation power for the maximal signal was around 1–1.5 μT for Cr with 20% cross‐linked BSA and in vivo applications, but 2 μT was found to be most practical for signal stability. For the CrCEST acquisition with strong MTC interference, the optimal saturation power and length are completely different from those on Cr solution alone. This observation could be explained well using R_1ρ theory by incorporating the strong MTC pool. Finally, a high‐resolution Cr map was obtained on mouse brain using the PLOF method with the NSS CEST acquisition and a cryogenic coil. The Cr map obtained by CEST showed homogenous intensity across the mouse brain except for regions with cerebrospinal fluid.     

Combined Effects of A Body Shape Index and Serum C-reactive Protein on Ischemic Stroke Incidence among Mongolians in China

Objective We aimed to evaluate the combined effects of a high body shape index(ABSI) and a high serum C-reactive protein(CRP) level on the incidence of ischemic stroke in a Mongolian population in China. Methods A prospective cohort study was conducted among 2,589 participants from June 2002 to July 2012 in Inner Mongolia, China. The participants were categorized into 4 groups according to their level of ABSI and CRP. Cox proportional hazards models were used to assess the hazard ratios(HRs) and 95% confidence intervals(CIs) for ischemic stroke among all groups. Results The multivariate adjusted HRs(95% CI) of ischemic stroke for high ABSI and high CRP level were 1.46(0.89-2.39) and 1.63(0.95-2.79), respectively. Compared with the low ABSI/low CRP level group, the multivariate adjusted HRs(95% CI) of ischemic stroke in the low ABSI/high CRP, high ABSI/low CRP, and high ABSI/high CRP groups were 1.04(0.46-2.35), 1.06(0.58-1.95) and 2.52(1.27-5.00), respectively. The HR of ischemic stroke for the high ABSI/high CRP level group was the highest and most statistically significant. Conclusion We found that participants with simultaneously high ABSI and high CRP levels had the highest risk of ischemic stroke in the Mongolian population. Our findings suggest that the combination of high ABSI and high CRP levels may increase the risk of ischemic stroke.     

Prostate shape significantly affects the HoLEP procedure time and energy usage: A retrospective pilot study

Introduction: In this study we evaluate the influence of longitudinal and transverse length of prostate size measured on the magnetic resonance imaging (MRI) scan on the overall outcomes of HoLEP.

Material and methods: The patients were divided into two groups based on the shape of the prostate. Group 1 had a longitudinal shape with a longitudinal diameter greater than the transverse diameter, whereas group 2 had an oval shape with a transverse diameter greater than the longitudinal diameter. The pre-operative, peri-operative and the one-month post-operative data along with the urinary parameters were then evaluated.

Results: The two groups were comparable with regard to their pre-operative values. While the median lobe enucleation time and morcellation time showed no difference, group 1 showed a significantly shorter (p?<?0.01) operative time for lateral lobe enucleation, lower laser energy usage and better enucleation efficiency. However, there was no difference in the median lobe enucleation time, morcellation time, haemoglobin drop, duration of urethral catheterization and hospital stay. The groups were also comparable with regard to the improvement in urinary parameters and complications.

Conclusion: Prostate shape plays a significant role in the surgical treatment of BPH.     

Development of PLGA micro- and nanorods with high capacity of surface ligand conjugation for enhanced targeted delivery

 Particle shape has been recognized as one of the key properties of nanoparticles in biomedical applications including targeted drug delivery. Targeting ability of shape-engineered particles depends largely on targeting ligands conjugated on the particle surface. However, poor capacity for surface ligand conjugation remains a problem in anisotropic nanoparticles made with biodegradable polymers such as PLGA. In this study, we prepared anisotropic PLGA nanoparticles with abundant conjugatable surface functional groups by a film stretching-based fabrication method with poly (ethylene-alt-maleic acid) (PEMA). Scanning electron microscopy images showed that microrods and nanorods were successfully fabricated by the PEMA-based film stretching method. The presence of surface carboxylic acid groups was confirmed by confocal microscopy and zeta potential measurements. Using the improved film-stretching method, the amount of protein conjugated to the surface of nanorods was increased three-fold. Transferrin-conjugated, nanorods fabricated by the improved method exhibited higher binding and internalization than unmodified counterparts. Therefore, the PEMA-based film-stretching system presented in this study would be a promising fabrication method for non-spherical biodegradable polymeric micro- and nanoparticles with high capacity of surface modifications for enhanced targeted delivery     

Development of three-dimensional facial expression models using morphing methods for fabricating facial prostheses

Purpose

It is essential to fabricate a best-fit three-dimensional (3D) facial prosthesis model capable of facial expressions. In order for the facial prosthesis to remain in position, especially around marginal areas subject to movement, a new method of making 3D facial expression models using time-series data allowing changes in facial expression by morphing technique was developed.

Quantitative Shape-Classification of Misfitting Precipitates during Cubic to Tetragonal Transformations: Phase-Field Simulations and Experiments

The effectiveness of the mechanism of precipitation strengthening in metallic alloys depends on the shapes of the precipitates. Two different material systems are considered: tetragonal γ′′ precipitates in Ni-based alloys and tetragonal θ′ precipitates in Al-Cu-alloys. The shape formation and evolution of the tetragonally misfitting precipitates was investigated by means of experiments and phase-field simulations. We employed the method of invariant moments for the consistent shape quantification of precipitates obtained from the simulation as well as those obtained from the experiment. Two well-defined shape-quantities are proposed: (i) a generalized measure for the particles aspect ratio and (ii) the normalized λ₂, as a measure for shape deviations from an ideal ellipse of the given aspect ratio. Considering the size dependence of the aspect ratio of γ′′ precipitates, we find good agreement between the simulation results and the experiment. Further, the precipitates’ in-plane shape is defined as the central 2D cut through the 3D particle in a plane normal to the tetragonal c-axes of the precipitate. The experimentally observed in-plane shapes of γ′′-precipitates can be quantitatively reproduced by the phase-field model.     

Parametric Optimization and Effect of Nano-Graphene Mixed Dielectric Fluid on Performance of Wire Electrical Discharge Machining Process of Ni55.8Ti Shape Memory Alloy

In the current scenario of manufacturing competitiveness, it is a requirement that new technologies are implemented in order to overcome the challenges of achieving component accuracy, high quality, acceptable surface finish, an increase in the production rate, and enhanced product life with a reduced environmental impact. Along with these conventional challenges, the machining of newly developed smart materials, such as shape memory alloys, also require inputs of intelligent machining strategies. Wire electrical discharge machining (WEDM) is one of the non-traditional machining methods which is independent of the mechanical properties of the work sample and is best suited for machining nitinol shape memory alloys. Nano powder-mixed dielectric fluid for the WEDM process is one of the ways of improving the process capabilities. In the current study, Taguchi’s L16 orthogonal array was implemented to perform the experiments. Current, pulse-on time, pulse-off time, and nano-graphene powder concentration were selected as input process parameters, with material removal rate (MRR) and surface roughness (SR) as output machining characteristics for investigations. The heat transfer search (HTS) algorithm was implemented for obtaining optimal combinations of input parameters for MRR and SR. Single objective optimization showed a maximum MRR of 1.55 mm³/s, and minimum SR of 2.68 µm. The Pareto curve was generated which gives the optimal non-dominant solutions.     

Influence of Cr3C2 and VC Content on WC Grain Size,WC Shape and Mechanical Properties of WC–6.0 wt. % Co Cemented Carbides

In this paper, the influences of Cr₃C₂/VC content on WC grain size, WC grain shape and mechanical properties of WC–6 wt. % Co cemented carbides were investigated. The results showed that the grain size first rapidly decreased and then slightly decreased with the increasing Cr₃C₂/VC content, and VC led to finer grain size and narrower size distribution. HRTEM/EDS analysis of the WC/Co interface indicates that the segregation concentration of V is much larger than that of Cr, which may be a strong response to the higher inhibition efficiency of VC. The addition of Cr₃C₂ induced triangular prism shape WC grains while VC generated stepped triangular prism grains. Despite the grain growth inhibitor (GGI) mechanisms of Cr₃C₂/VC have been extensively studied in the literature, the doping amount, especially the doping limit, has not been systematically investigated. In this work, the saturated solubilities of Cr and V in cobalt binder phase along with carbon content hare been predicted based on thermodynamic calculations. Based on the theoretical calculations, the doping amount of Cr₃C₂/VC is designed to be gradually increasing until more or less over their maximum solubilities in the binder phase, thereby investigating the subsequent microstructure and mechanical properties. When the doping of Cr₃C₂/VC exceeds the maximum solubility in Co phase, Co-rich Cr-carbides and Co-deficient V-carbides would form respectively, which were detrimental to the transverse rupture strength (TRS) and impact toughness. The hardness increased with the increasing Cr₃C₂/VC content, while the fracture toughness decreased with the increasing Cr₃C₂/VC content. The TRS initially enhanced and then declined, but the stepped triangular prism shape grains and low fraction of WC/Co interface in WC–6Co–VC cemented carbide led to a more pronounced decline in the TRS. The sample with 0.6 wt. % Cr₃C₂ addition had good comprehensive mechanical properties, its hardness, fracture toughness and TRS were 1880 kg/mm², 9.32 MPa·m^1/2 and 3450 MPa, respectively.